Water-stable lithium anode with LAGP sheet prepared by tape casting method for lithium-air batteries

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第四部分_锂离子电池

负极活性物质：常选用较活泼金属
介绍金属锂
锂是银白色金属，熔点180.5℃，比重：0.534g/cm3。化学性质活泼，在潮湿空气中迅速失去光泽，形成氧化锂、氢氧化锂和碳酸锂的混合物覆盖层。需存放在惰性气体、干燥气体或矿物油中。
二、电解质
The electrolyte — the ionic conductor—which provides the medium for transfer of charge, as ions, inside the cell between the anode and cathode. The electrolyte is typically a liquid, such as water or other solvents, with dissolved salts, acids, or alkalis to impart ionic conductivity. Some batteries use solid electrolytes, which are ionic conductors at the operating temperature of the cell.
正极
隔膜
枝晶
Only few hundreds cycle with low DOD possible Using insertion materials

负极（锂片）
Replacement of lithium metal by
lithium insertion material
+ -
嵌锂化合物

正极材料LiCoO2，负极材料 C（CLix）
§4.1.2锂电池的发展概况
期间经历了一次锂电池；二次锂电池；二次锂离子电池.

杏鲍菇废弃菌渣中D-氨基葡萄糖盐酸盐的制备工艺及生物学活性分析

张倩如，吴启赐，薛钰，等. 杏鲍菇废弃菌渣中D-氨基葡萄糖盐酸盐的制备工艺及生物学活性分析[J]. 食品工业科技，2023，44（17）：263−271. doi: 10.13386/j.issn1002-0306.2022110139ZHANG Qianru, WU Qici, XUE Yu, et al. Preparation and Biological Activity of D-Glucosamine Hydrochloride from the Waste Residues of Pleurotus eryngii [J]. Science and Technology of Food Industry, 2023, 44(17): 263−271. (in Chinese with English abstract).doi: 10.13386/j.issn1002-0306.2022110139· 工艺技术 ·杏鲍菇废弃菌渣中D-氨基葡萄糖盐酸盐的制备工艺及生物学活性分析张倩如1，吴启赐1, *，薛　钰1，林志超1，黄家福1，吕昊坤1，彭　伟1，潘裕添1，林进妹2,*（1.闽南师范大学菌物产业福建省高校工程研究中心，福建漳州 363000；2.闽南师范大学化学化工与环境学院，福建漳州 363000）摘　要：本文以杏鲍菇废弃菌渣为原料，探究了D-氨基葡萄糖盐酸盐（D-glucosamine hydrochloride ，GAH ）的制备工艺、液相-质谱（HPLC-MS ）、红外光谱、理化指标及其对斑马鱼胚胎发育的影响。

采用单因素和响应面优化试验，获得盐酸水解制备GAH 的最佳条件：盐酸浓度31%，水解时间4 h ，水解温度82 ℃，液固比5 mL/g ，此时GAH 得率可达23.61%。

液相-质谱、红外光谱和理化指标分析显示，GAH 纯化样品纯度是标准品的101.9%，质谱和红外光谱图与标准品一致，各项指标均符合甚至优于美国药典43-国家处方集38（USP43-NF38）的质量标准，砷含量仅0.21 μg/g 。

密度泛函理论研究叶绿素a水合物的结构、结合能和电离能

密度泛函理论研究叶绿素a水合物的结构、结合能和电离能谷靖;王一波【摘要】用M06-2X／6-311G（d，P）密度泛函理论对叶绿素a及其两种水合物的结构进行优化，然后用M06-2X／6-311＋＋G（2d，2p）方法计算结合能和电离能。

优化结果表明水合分子会使叶绿素a分子结构发生改变。

结合能计算结果表明叶绿素a的二水合物比一水合物更为稳定。

电离能计算结果表明随着叶绿素a水合分子数的增加，电离能逐渐减小，叶绿素a的水合有利于光合作用的发生。

%The structures of chlorophyll-a and its two hydrates were optimized at the level of density functional theory M06-2X/6-311G （d, p）, and the binding energies and ionization energies were calculated using M06-2X/ 6-311 ＋＋ G （2d, 2p） method. The optimized results show that the water can change the structure of chlorophyll- a. The results of binding energies suggest that the chlorophyll-a dihydrate is more stable than monohydrate. The i- onization energy results indicate that the ionization energies decrease gradually with the increase of the number of water, and photosynthesis is more likely to occur with the existence of water.【期刊名称】《贵州科学》【年(卷),期】2012(030)004【总页数】5页(P9-12,28)【关键词】叶绿素a;水合;结构;结合能;电离能【作者】谷靖;王一波【作者单位】贵州省高性能计算化学重点实验室贵州大学,贵阳550025;贵州省高性能计算化学重点实验室贵州大学,贵阳550025【正文语种】中文【中图分类】Q176在高等植物的光合作用中，叶绿素a既作为能量传递过程中的接受体和传递体，又作为电子传递链上的供体和受体，显得十分重要(Yang，2011)。

Chitosan, a new and environmental benign electrode binder

Electrochimica Acta 105 (2013) 378–383Contents lists available at SciVerse ScienceDirectElectrochimicaActaj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e l e c t a c taChitosan,a new and environmental benign electrode binder for use with graphite anode in lithium-ion batteriesLili Chai a ,Qunting Qu a ,Longfei Zhang a ,Ming Shen b ,Li Zhang a ,∗,Honghe Zheng a ,∗a School of Energy,Soochow University,Suzhou,Jiangsu 215006,China bHuasheng Chemical Corporation,Zhangjiagang,Jiangsu 215635,Chinaa r t i c l ei n f oArticle history:Received 22March 2013Received in revised form 30April 2013Accepted 6May 2013Available online 14 May 2013Keywords:Lithium-ion batteries Graphite anode Electrode binder Chitosana b s t r a c tChitosan was applied as the electrode binder material for a spherical graphite anode in lithium-ion pared to using poly (vinylidene ﬂuoride)(PVDF)binder,the graphite anode using chitosan exhibited enhanced electrochemical performances in terms of the ﬁrst Columbic efﬁciency,rate capabil-ity and cycling behavior.With similar speciﬁc capacity,the ﬁrst Columbic efﬁciency of the chitosan-based anode is 95.4%compared to 89.3%of the PVDF-based anode.After 200charge–discharge cycles at 0.5C ,the capacity retention of the chitosan-based electrode showed to be signiﬁcantly higher than that of the PVDF-based electrode.Electrochemical impedance spectroscopy (EIS)and scanning electron microscopy (SEM)measurements were carried out to investigate the formation and evolution of the solid electrolyte interphase (SEI)formed on the graphite electrodes.The results show that a thin,homogenous and stable SEI layer is formed on the graphite electrode surface with chitosan binder compared with that using the conventional PVDF binder© 2013 Elsevier Ltd. All rights reserved.1.IntroductionElectrode binder plays a very important role in fabricating high-performance electrodes as it holds active materials and conductive additives into a cohesive laminate and provides the adhesion between the laminate and the current collector.In the past two decades,poly (vinylidene ﬂuoride)(PVDF)was the most widely used binder material for Li-ion battery electrodes.This is attributed to its good electrochemical stability,binding capability and ability to absorb electrolyte [1–5].However,PVDF polymer is costly and it requires the use of environmentally unfriendly N-methyl pyr-rolidone (NMP)solvent in the processing.Besides,this polymer is very sensitive to the environmental humidity.It undergoes a severe degradation of viscosity after absorbing water.As a ﬂuorinated polymer,PVDF also shows a certain reactivity against lithium metal and lithiated graphite (Li x C 6),producing resistive LiFand C CF species on the electrode surface,especially at elevated tempera-tures [6,7].For these reasons,the development of greener,cheaper and more electrochemical stable electrode binder is considered as a goal of strategic importance for battery technologies.In recent years,many groups have been studying new electrode binder materials for the realization of greener battery processing and∗Corresponding authors.E-mail addresses:hhzheng@ (L.Zhang),zhangli81@ (H.Zheng).high performance Li-ion batteries.Among different binder systems,water-soluble binders are not only much cheaper than PVDF,but also allow electrode processing in aqueous slurries.These polymers can be easily disposed at the end of the life of the battery.Gelatin [8–11],sodium carboxy-methyl cellulose (CMC-Na)and styrene-butadiene rubber (SBR)[12–18],poly(acrylic acid)(PAA)[19–23],poly(methacrylic acid)(PMA)[24],poly(vinyl alcohol)(PVA)[25],alginate [26,27],poly(acrylamide-co-diallyldime-thylammonium chloride (AMAC)[28],poly (acrylonitrile-methyl methacrylate)(AMMA)[29],and polyimide (PI)[30],all have been reported as promising new binder systems replacing PVDF and some of them have been successfully used in commercial lithium ion batter-ies.In this paper,chitosan,as a water-soluble polymer,was adopted as a new electrode binder for a graphite anode.Chitosan is a polysaccharide composed mainly of ␤-(1,4)-linked 2-deoxy-2-amino-d -glucopyranose units.The molecular structure of it is provided in Fig.1.This polymer is one of the most plentiful nat-ural biopolymers produced from poly (N-acetyl-d -glucosamine)(chitin)[31].Chitosan is widely used in many ﬁelds including molecular separation,food packaging ﬁlm,artiﬁcial skin,bone substitutes,water treatment and so on [32–34].In Li-ion battery ﬁeld,chitosan has also been attempted as the template for active material synthesis [35],and carbon coating precursor [36].How-ever,to the best of our knowledge,this polymer has never been adopted as an available binder material for Li-ion batteries up to today.0013-4686/$–see front matter © 2013 Elsevier Ltd. All rights reserved./10.1016/j.electacta.2013.05.009L.Chai et al./Electrochimica Acta105 (2013) 378–383379Fig.1.The molecular structure of chitosan polymer.As the matter of fact,chitosan-based aqueous slurry possesses good viscosity,which can be considered as an effective electrode binder.Herein,acid solution-based chitosan slurry was applied as the binder for a commercial spherical graphite material.Elec-trochemical performances of the chitosan-based and PVDF-based graphite anodes were compared in terms of reversible capacity,ﬁrst Coulombic efﬁciency,rate capabilities and long-term cycling behavior.Electrochemical impedance spectroscopy(EIS)and scan-ning electron microscopy(SEM)measurements were performed to investigate the effect of binder on the formation and evolution of the solid electrolyte interphase(SEI)layer on the graphite elec-trode.Mechanisms for the higher electrochemical performance of the graphite anode with chitosan binder were discussed2.ExperimentalSpherical graphite powders(Shenzhen Beterui new energy Materials Group Co,Ltd Code No AGP-8,China)were applied as the electrode active material.Acetylene black(AB)with an average particle size of40nm was acquired from Denka Singapore Private Ltd PVDF(KF1100)binder was obtained from Kureha,Japan and chitosan(Code No C0831)was purchased from TCl Shanghai.All the materials were used as received in this study.PVDF was dissolved into NMP solvent(aladdin,anhydrous, 99.9%)with a concentration of15wt%while chitosan was dis-persed into0.5%acetic acid solution with a concentration of3wt% at room temperature.Even though the concentration of the PVDF-based solution is much higher,viscosity of the aqueous solution containing3wt%chitosan seems to be slightly higher than that of the15wt%PVDF solution.Both solutions were equilibrated for at least2h at room temperature with magnetic stirring.For the preparation of the electrodes,slurry consisting of94wt%graphite powders and6wt%chitosan was thoroughly mixed for12h and casted onto15␮m-thick copper foil(99.99%purity).As a refer-ence,the electrode using PVDF binder was prepared by casting the slurry containing88.8wt%graphite,3.2wt%super P and8wt% PVDF.The recipes were obtained in our lab as described in the lit-erature[37]for making high electrochemical performance MCMB anode.Both the two electrode laminates were controlled to have the same active material loading of∼1.8mg cm−2by varyingthedoctor blade height.The obtained electrodes were dried at120◦Cin a vacuum oven for16h and pressed to enhance the mechanicalcontact between the electrode laminate and current collector. Fig.2.SEM images of as-prepared graphite electrodes with chitosan(a and b)and PVDF binder(c and d).380L.Chai et al./Electrochimica Acta010020030 0400.00.51.01.52.02.53.0221Specific capacity (mAh.g -1)V o l t a g e v s . L i /L i + (V )1-W ater-based e lectrode 2-PVDF-based e lectrode1Fig.3.The ﬁrst charge–discharge proﬁles of the graphite anode using (a)chitosanand (b)PVDF binder.The half cells (2032stainless-steel coin cell)were assembled in an Ar-ﬁlled glove box (OMNI-LAB,VAC).The electrolyte was 1M LiPF 6in ethylene carbonate/diethylene carbonate (EC/DEC,1:1by weight)with 10%ﬂuoroethylene carbonate (FEC)as the addi-tive (Novolyte Technologies).The separator employed was Celgard 2400and lithium metal foil (99.9%purity)was utilized as the counter electrode.All the cells were tested on a Maccor S4000(Maccor Instruments,USA)at 303K in a Thermotron Environmen-tal Chamber.Three formation cycles at C/20charge and discharge were applied between 0.005V and 2V vs Li.Rate test of the graphite electrodes consisted of full discharges at rates of C/10,C/5,C/2,1C ,2C ,5C ,and 10C ,respectively.Long-term cycling of the cells was carried out with 0.5C charge and 0.5C discharge for 200cycles.Electrochemical impedance spectroscopy (EIS)was measured by applying an alternating voltage of 5mV over the frequency ranging from 10−2to 105Hz.All impedance measurements were carried out at the discharge state of 60%DOD (depth of discharge)at different cycling stages.Morphologies of the graphite electrodes using different binders before and after electrochemical tests were observed by scanning electron microscopy (SEM)using a Hitachi S-4700operated at 1kV and 5kV accelerating voltage.3.Results and discussionSEM images of the as-prepared graphite electrodes with chi-tosan and PVDF binders are presented in Fig.2at different magniﬁcations.As there is no conductive carbon additive,only smooth and “clean”graphite particles are observed for the elec-trode with chitosan binder (as seen in Fig.2a,b).The graphite particle size is around 10␮m in the image.By contrast,as shown in Fig.2c,d,lots of nano-scale conductive carbon particles are seen well distributed in between the graphite particles.It has been reported that PVDF binder tends to shrink and cover the graphite powders,which blocks the migration of Li ion during electrochem-ical processes [38].Addition of conductive carbon additive within the PVDF-based electrode not only contributes to an improvement of the electronic conductivity of the laminate,but also helps to increase the electrode porosity.Fig.3shows the charge–discharge proﬁles of the graphite anodes using different binders in 1M LiPF 6/(EC:DEC)electrolyte containing 10%FEC.FEC is used as the electrolyte additive as it signiﬁcantly improves electrochemical performances of graphite anode in the electrolyte and is now widely used in Li-ion battery R&D.For the two kinds of electrodes,the cell voltage drops rapidly from open circuit voltage down to 0.2V,corresponding to theof is at is at ofL.Chai et al./Electrochimica Acta 105 (2013) 378–38338180859095100105%/n o i t n e t e r y t i c a p a c e l b i s r e v e R Cycle nu mberFig.5.Rate capability of the graphite electrodes using (a)chitosan and (b)PVDFbinder.electrode using PVDF binder.The higher rate capability of chitosan-bonded graphite electrode seems not very identical with the highpolarization of the electrode in the ﬁrst charge and this will be discussed next.Fig.6displays the cycling performance of the graphite anodes with chitosan and PVDF binders.As shown in this ﬁgure,chitosan-based graphite anode shows better cycling performance than the PVDF-based electrode.Upon deep galvanostatic cycling for 200cycles,the capacity retention of the chitosan-based electrode is no less than 91%while the capacity retention of the PVDF-based electrode is no more than 75%at the same cycling condition.The improved cycling capability of the electrode by using Chitosan binder illustrates better electrochemical stability of the electrode during electrochemical cycles.In order to explain the higher rate performance and cycling capability of the graphite anode using chitosan binder,elec-trochemical impedance spectroscopy (EIS)measurements of the graphite anode using different binders at different cycling stages were performed at 60%DOD and the results are displayed in Fig.7.All the sets consist of two semicircles [39].The high-frequency semicircle is believed to be related to the resistance of passivating SEI ﬁlm (R SEI )or active material particle-to-particle interfacial con-tact resistance.The intermediate-frequency semicircle is attributed to the charge–transfer resistance (R ct ).For the chitosan-based20406080100%/n o i t n e t e r y t i c a p a c e l b i s r e v e R Cycle numberFig.6.Cycling performance of the graphite electrodes using chitosan (a)and PVDF (b)binder at 0.5C charge and 0.5C discharge.51015202530-Z '' / O h mZ' / Ohm10203040-Z '' / O h mZ' / OhmFig.7.Nyquist plots of graphite electrodes using chitosan (a)and PVDF (b)binder at different cycling stages at 60%DOD.electrode,higher impedance after formation cycles are observed compared to that of electrode using PVDF binder.The high resistance is most likely to be related to the graphite particle-to-particle interfacial contact resistance as there is no conductive carbon within the electrode matrix.The high impedance explains the higher polarization of the electrode in the ﬁrst charge as shown in Fig.4.However,after the rate test,it is clear to see that impedance of chitosan-based electrode exhibits a remarkable decrease and the impedance seems to be even lower than that of PVDF-based electrode at this stage.The decrease of electrode impedance with electrochemical cycle implies an activation process for chitosan-bonded electrode.Along with the repeating lithiation/delithiation processes,more ion transport and charge–transfer sites may be created at the electrode/electrolyte interface,which leads to the electrode impedance decreases.Actually,this phenomenon always occurs for graphite anode with water soluble binders [28].The lower impedance for the chitosan-based electrode explains the high rate performance at this stage.After 200cycles,impedance of the chitosan-based anode is well maintained and even shows a continuous decrease of R ct .By comparison,a slight increase of R ct for the PVDF-based electrode is observed.Again,this result conﬁrms that the surface condition of electrode using chitosan binder is relatively stable with electrochemical cycles.For the PVDF-based anode,the increase of electrode impedance indicates continuous growth of the surface components during the long-term cycling test.According to these analyses,chitosan presents obvious advantages in fabricating high-performance anode compared with conventional PVDF binder.382L.Chai et al./Electrochimica Acta 105 (2013) 378–383Fig.8.SEM images of graphite electrodes after formation and rate capability test,chitosan binder (a),(b);PVDF binder (c),(d).To clearly see the surface condition of the graphite anode with different binders after electrochemical cycles,scanning elec-tron microscopy (SEM)measurements were carried out.Fig.8presents the SEM microscope images of graphite anode with dif-ferent binders after formation cycles and after the rate capability test.After the formation cycles,many alien particles and fragments are seen dispersed on the graphite surface of the PVDF-based anode (Fig.8c)while few alien particles can be detected on the graphite surface with chitosan binder (Fig.8a).This agrees with the lower irreversible capacity loss of the electrode in the ﬁrst cycle.After the rate capability tests,the graphite surface of the PVDF-based elec-trode became even more rough and thicker,with a lot of agglom-erate granules and fragments staying on the electrode surface (see Fig.8d).This evidence also supports our conclusion that the elec-trode with chitosan binder has better electrochemical stability.4.ConclusionChitosan was applied as an effective binder for graphite anode in Li-ion pared to the electrode using conventional PVDF binder,the ﬁrst Columbic efﬁciency,rate capability and cycling behavior are considerably improved EIS studies showed that the electrode resistance of the chitosan-based electrode under-goes a distinct decrease after the initial several cycles and the electrode impedance is well maintained after long-term cycling tests.Meanwhile a continuous growth of electrode resistance with electrochemical cycles is observed for the electrode with PVDF binder.This is consistent with the continuous growth of the surface species with increasing electrochemical cycles.At last,it should be noted that many key physical parameters involved in making chitosan-based electrode are not optimized in this study.Given the chitosan content and electrode processing technologies are optimized,the results may be even more optimistic.AcknowledgementsThe authors are greatly indebted to the funding of Natural Sci-ence Foundation of China (NSFC,contract no 21073129,51272168,21203132,and 21203133).References[1]J.Chong,S.D.Xun,H.H.Zheng,X.Y.Song,G.Liu,P.Ridgway,J.Q.Wang,V.S.Battaglia,A comparative study of polyacrylic acid and poly(vinylidene diﬂuo-ride)binders for spherical natural graphite/LiFePO 4electrodes and cells,Journal of Power Sources 196(2011)7707–7714.[2]A.Fedorkova,R.Orinakova,A.Orinak,I.Talian,A.Heile,H.D.Wiemhofer,D.Kaniansky,H.F.Arlinghaus,PPy doped PEG conducting polymer ﬁlms synthe-sized on LiFePO 4particles,Journal of Power Sources 195(2010)3907–3912.[3]G.Liu,H.Zheng,A.S.Simens,A.M.Minor,X.Song,V.S.Battaglia,Optimizationof acetylene black conductive additive and PVDF composition for high-power rechargeable lithium-ion cells,Journal of the Electrochemical Society 154(2007)A1129–A1134.[4]N.S.Choi,Y.G.Lee,J.K.Park,Effect of cathode binder on electrochemical prop-erties of lithium rechargeable polymer batteries,Journal of Power Sources 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锂离子电池陶瓷复合全固态电解质的制备和性能研究

锂离子电池陶瓷复合全固态电解质的制备和性能研究李承斌;岳红云;王秋娴;李静娴;杨书廷【摘要】Poly(ethylene oxide) (PEO) as a kind of promising candidates of polymer electrolyte is widely applied in all solid lithium ion batteries. In this study, a novel ceramic composite solid electrolyte (CLASP) was prepared by dip-coating PEO-LAGP-SN-LiTFSI (PEO-SPE) into Al2O3 nonwoven membrane. And all solid batteries were assembled with CLASP. CLASP showed excellent thermostability even at 170℃ for 2 h. When the ratio of PEO: LAGP: SN: LiT-FSI was 3: 1: 1: 1, the conductivities of CLASP reached 3.66×10-5 S/cm at 25℃ and 2.52×10-4 S/cmat 100℃, re-spectively. The electrochemical window of CLASP was 5.5 V, which had great potential to apply in battery with high voltage cathode material. The cycling performance of all solid batteries with CLASP was greatly improved at 55℃ as well. This new ceramic composite, solid polymer electrolyte, with all these outstanding performance is a promising candidate of all solid electrolytes.%以负载Al2O3的无纺布为支撑膜,浸涂PEO-LAGP-SN-LiTFSI的乙腈共混液干燥后制得新型复合固态电解质膜(CLASP).该膜的热稳定性好,即使在170℃的高温下依然不发生形变.当浸涂共混液中PEO:LAGP:SN:LiTFSI为3:1:1:1,固含量为10wt％时,室温电导率可以达到3.66×10-5 S/cm,100℃时电导率可达2.52×10-4 S/cm.CLASP膜的电化学窗口宽,以该膜代替液态电解质装配的全固态LiFePO4/CLASP/Li电池,在55℃循环时表现出良好的循环稳定性,高的库伦效率,有望成为电化学性能优越的全固态电解质.【期刊名称】《无机材料学报》【年(卷),期】2017(032)008【总页数】5页(P801-805)【关键词】全固态;复合电解质;磷酸锗铝锂;耐热【作者】李承斌;岳红云;王秋娴;李静娴;杨书廷【作者单位】河南师范大学物理与材料科学学院,新乡453007;河南工学院电气工程系,新乡453003;河南师范大学化学化工学院, 动力电源及关键材料国家地方联合工程实验室, 新乡453007;河南师范大学化学化工学院, 动力电源及关键材料国家地方联合工程实验室, 新乡453007;河南师范大学化学化工学院, 动力电源及关键材料国家地方联合工程实验室, 新乡453007;河南师范大学物理与材料科学学院,新乡453007;河南师范大学化学化工学院, 动力电源及关键材料国家地方联合工程实验室, 新乡453007【正文语种】中文【中图分类】Q152自从1991年索尼开发出商用锂离子电池以来, 锂离子电池以其具有高的能量密度, 无记忆效应, 环境友好等特点被广泛应用于手机和笔记本等数码产品中[1-3]。

Ocean Free Hydra Internal Filter and Hydra Stream产

Hydro-Pure Technology: Frequently Asked Questions (FAQs)FAQs for Ocean Free Hydra Internal Filter and Hydra Stream products powered by Hydro-Pure Technology •What is Hydro-Pure Technology?•Hydro-Pure Technology is a patented water detoxifying and depurating system designed for the hobby of fishkeeping. It consists of two electro-plates which energize a cartridge box containing special Cata-Pure Media to release strongly reactive Hydroxyl (OH-) ions, which is the key to the detoxifying anddepurating reaction process.•Understanding Ammonia and Ammonium in your aquarium:•Ammonia is un-ionized, and has the formula NH3. Ammonium is ionized, and has the formula NH4+.The major factor that determines the proportion of ammonia or ammonium in water is the pH of thewater The activity of ammonia is also influenced by temperature and ionic strength. This is important, asthe un-ionized NH3 form of ammonia can be toxic to aquatic organisms, while the ionized NH4+ form isessentially harmless to aquatic organisms.•The chemical equation that drives the relationship between ammonia and ammonium is:NH3 + H2O ↔NH4+ + OH-•What is the working principle and benefits of Hydro-Pure Technology?•Hydro- Pure Technology creates safe and stable “Hydro-Pure Water” similar to that of natural rivers and streams which is rich in micronutrients and minerals. It constantly pushes the ionization of toxicAmmonia (NH3) into non-toxic Ammonium (NH4+), thus helping prevent any harmful effects to fish dueto exposure to toxic Ammonia. Ammonium cannot be absorbed into the fish gills.NH3+ H2O ↔ NH+4 + OH-•It also helps to oxidize toxic Nitrites (NO2-) to non-toxic Nitrates (NO3-), keeping it stable and at a safe level. In the continuous chain reactions within the water, the Total Ammonia Nitrogen (NH3 and NH4+)will eventually become free Nitrogen (N2) and water (H2O).•Hydro-Pure Technology can also help prevent cloudiness through the ionization of any solid precipitation that is present in the waters.•It also helps control and remove disagreeable odours through the oxidization of sulphur-based products.•Hydro-Pure Technology is suitable for marine and freshwater fish tanks of all sizes, all types of fishe, plants and live corals and all levels of stocking density. It also helps in the prevention of“New Tank Syndrome” especially in Marine tanks. It is also suitable for all applications that requirepristine water conditions with safe and stable levels of Ammonia, nitrites and nitrates, such as for thebreeding of Red Crystal Shrimps, etc.•Why does my Ammonia Test Kit read high levels of Ammonia after using the Hydro-Pure Technology products?•Do not panic. Most Ammonia test kits on the market measure Total Ammonia Nitrogen (TAN). They measure the total sum of toxic Ammonia (NH3) and non-toxic Ammonium (NH4+) in the water. Hydro-Pure Technology detoxifies Ammonia (NH3) by constantly pushing the ionization of toxic Ammonia NH3.Therefore, it is normal that these test kit results in high readings as they measure total sum of both toxicAmmonia (NH3) and non-toxic Ammonium (NH4+) together. Research has also shown that mostaquatic plants are able to take in Ammonium directly for their nitrogen requirements.•Why does the Nitrate (NO3-) level rise slightly during the first few days of using the Hydra?•The Nitrite (NO2-) in the water will be oxidized to become Nitrate (NO3-) in the initial stages, but it will gradually become stable and drop to a safe level.•Why does my Phosphate Test Kit read high levels of Phosphate after using Hydra Product?•Hydra has the capability to precipitate Phosphate PO4 into solid form, and this can be more easily read by Phosphate Test Kits available in the market. However, the good thing is that precipitated Phosphatecannot be taken in by algae, so levels of algae will likely be reduced.•Can I use the Hydra product continuously?•Yes. It is ok to keep your Hydra switched on continuously.•Hydra will not affect the inhabitants of your aquarium.•It is however recommended that you switch off the power of your Hydra stream during medication. For the Hydra Internal filter, please remove the cartridge. This is to prevent your Hydra from affecting themedication.•What is “Cata-Pure”?•“Cata-Pure” is the name of the cartridge media used in Hydro-Pure Technology.•What is the usage life of the Cata-Pure cartridge?•Cata-Pure media can be used continuously for up to 12 months.•Regular washing and rinsing is necessary to remove any dirt that has accumulated within the cartridge.•Replace the cartridges every 12 months for maximum performance.•Is Cata-Pure made of Activated Carbon?•Cata-Pure is a carbon-based media that has been specially formulated with additives to work with Hydro-Pure Technology.•Replacing Cata-Pure with activated Carbon will not work, and may even cause damage to the unit.•Do I have to clean the Cata-Pure Cartridge?•Yes. Regular maintenance is necessary to ensure that the Cata-Pure Cartridge does not get clogged with dirt.•Clean the Cata-Pure whenever you are cleaning the filtration.•How do I clean the Hydra and Cata-Pure Cartridge?•Remove the Cata-Pure cartridge out of the Hydra unit.•Rinse and shake the cartridge in water to release dirt.•Clean the cartridge exterior.•Clean the Electro-Plate surface.•Re-insert the cartridge into the Hydra Unit.•Are the electro-plates replaceable?•The electro-plates are made of titanium and do not need to be replaced throughout the entire operating life of the product. Regular cleaning is however recommended for optimum performance.•Why does one of the electro-plate’s surfaces turn brownish?•It is normal for one of the electro-plate’s surfaces to change colour in this way due to the deposits created by the chemical reaction.•Please clean the electro-plate’s surface during maintenance.•What is a Hydra Internal Filter?• A Hydra Internal Filter is basically a normal internal filter with Hydro-Pure Technology capability built in. •Which Hydra Internal Filter should I use?•Select your Hydra Internal Filter based on the flow rate and tank size you require for your aquarium.Please refer to the guidelines below.•How do I use a Hydra Internal Filter?•Your Hydra Internal filter needs to be fully submerged into the aquarium water.•It can be placed inside the main Aquarium Tank.•It can also be placed inside a Filtration system, such as a Sump Tank’s compartment, preferably after the mechanical filtration compartment.•What is a Hydra Stream?•Hydra Stream is an in-line canister adapter with Hydro-Pure Technology capability built in.•It is used as an enhancement to the main filtration system.•It needs to be connected into the back of a filtration system driven by a pump.•Which Hydra Stream should I use?•Select the size of your Hydra Stream size based on the volume of water to treat. Please refer to the guidelines below.•How do I use a Hydra Stream?•The Hydra Stream is an adapter unit. It is not a complete filter system.•Your Hydra Stream should be connected to a filtration flow system, preferably at the back end after the mechanical or bio-filtration phase, such as at the outlet of a canister filter.•Your Hydra Stream can also be attached with a pump and submerged into a sump tank compartment.•Is Hydra Stream waterproof?•Yes, the Hydra Stream unit is completely waterproof and may be fully submerged.•Does the Hydra Stream have a fix inlet and outlet direction?•The Hydra Stream is designed as a pass-through adapter. Any flow direction is fine.•Can I use a bigger Hydra on a small volume of water?•Yes you may do so. A bigger hydra will be more efficient and will not cause any over-reaction.•Can I use a smaller Hydra on a bigger volume of water?•Yes you may do so, but the efficiency will be reduced on a larger volume of water.•Can it be used in marine tank?•Yes.•Can it be used in freshwater tank?•Yes.•Can it be used in Planted Tank Setup?•Yes. A well balanced nitrogen cycled planted tank may develop algae in the first few days of using Hydra due to the rapid depletion of nutrients. It is advisable to partially change about 10% of the waterto prevent algae growth. The Hydra will stabilize the water quality thereafter.•Will the Hydra kill or react with beneficial bacterial?•Hydro-Pure technology will oxidize bacteria, but all good bacteria needs to adhere to a surface, those floating around free would be very low in number, so Hydro Pure technology will not affect the bio-filtration system.•Hydroxyl (OH) ions produced from the Hydra do not react with or kill live bacteria.•How often do I need to clean my Hydra Internal filter/ Hydra Stream?• A reduction in the flow rate indicates a clogged system. Please clean and maintain the Hydra Internal filter and Hydra Stream on a regular basis.•Does Hydro-Pure Technology affect the pH of the water?•There is no significant effect on pH of the water.•Will Hydra affect any fish medications?•During medication, please switch off the power of the Hydra Stream. For the Hydra Internal filter, please remove the cartridge. This is to prevent Hydra from affecting the medication.•Will Hydra’s reaction affect black water solution?•No.•Will Hydra’s reaction affect vitamins?•No.•Will Hydra’s reaction affect any water conditioner?•No.•Will Hydra’s reaction affect Nature Earth?•No.•Does it mean that it is not necessary to change the aquarium water at all after using the Hydro-Pure Technology products?•Hydro-Pure Technology helps to maintain stable, high-quality water, therefore it will greatly reduce the frequency of water changes. The user will however still need to check the water quality regularly anddetermine if a partial or total water change is necessary.•Does Hydro-Pure Technology help to remove/ prevent algae in the aquarium?•Algae develop due to many factors such as high nitrates, high oxygen and lighting exposure…etc.Different types of Algae need different conditions to grow. Hydro-Pure Technology helps to keep Nitritesand Nitrates at safe and low level, so it should help in algae problems to a certain extent, depending onthe aquarium conditions.•With Hydro-Pure Technology, does it mean that it is not necessary to use bio-media to cultivate beneficial bacteria?•In any aquarium setup, the more filtration media you have, the better it is. It all depends on the aquarium setup and bio-load. Depending on the extent of Hydro-Pure Technology usage, a reducedamount of Bio media will be adequate for the tank system.•Can I modify the hydra’s electro-plates and Cata-Pure cartridges?•No. Do not attempt to modify or use the Hydra in any other way. Serious injury may occur if you do so.•We will not be liable for any damage or injury inflicted due to illegal modifications and improper usage of Hydra Technology.•Will I get an electric shock if I touch the Hydra’s Electro-Plates?•The Electro-Plates are powered by low level DC voltage which is safe and will not cause any electric shock.•However, it is advisable that you switch off the Hydra’s Power whenever you are doing maintenance to it.。

固定化光合细菌转化预水解液(PHL)的制氢研究

陕西科技大学学报Vol. 39 No. 2Apr 2021第39卷第2期2021年4月Journal of Shaanxi University of Science & Technology文章编号：2096-398X (2021 )02-0016-07固定化光合细菌转化预水解液(PHL )的制氢研究陈朵】，王雪青1*,张安龙2,罗清】，王浩楠*收稿日期：2020-10-28基金项目：陕西省科技厅自然科学基金项目(2017JQ5097)；陕西科技大学博士科研启动基金项目(2016QNBJ-04)作者简介：陈朵(1996 — )女，陕西西安人，在读硕士研究生，研究方向：预水解液的生物处理与转化通讯作者：王雪青(1986 —)，女，甘肃武威人，副教授，博士，研究方向：造纸工业废水生物处理，wangxueqing@sust. edu. cn(1.陕西科技大学轻工科学与工程学院轻化工程国家级实验教学示范中心，陕西西安710021； 2.陕西科技大学环境科学与工程学院，陕西西安710021 )摘要：通过对几种天然高分子聚合材料及其复合物的形貌、透光性、机械强度和化学稳定性等性能的比较，综合选择最优的材料作为光合细菌固定化载体，并对固定化条件进行优化.结果表明,2%琼脂和2%卡拉胶在以1 : 1混合时制备的固定化颗粒的性能最优，最适宜的固定化条件为在2%的KCl 中固定60 min,细菌包埋量为40 mL (菌液)/6 mL (固定化材料).随后，以模拟预水解液(PHL )作为底物，采用琼脂-卡拉胶固定光合细菌形成微球，对其产氢性能进行分析.结果表明，第二次循环的产氢量为第一次的1. 8倍，木糖利用率最高可达99. 4%，苯酚降解率最大为28. 5%，并且系统的pH 相对平稳.固定化光合细菌在连续六个循环中仍能保持较高的产氢性能，表明固定化微球具有稳定的重复利用性，具有良好的应用前景.关键词：琼脂-卡拉胶；光合细菌；固定化；预水解液；制氢中图分类号：X793文献标志码：AStudy on hydrogen production by immobilized photosynthetic bacteria transformed into pre-hydrolyzed liquid (PHL)CHEN Duo 1 , WANG Xue-qing 1* , ZHANG An-ong 2 , LUO Qing 1 , WANG Hao-nan 1(1. College of Bioresources Chemical and Materials Engineering , National Demonstration Center for Experi mental Light Chemistry Engineering Education , Shaanxi University of Science & Technology , Xi'an 710021 , China ； 2. School of Environmental Science and Engineering , Shaanxi University of Science & Technology, Xi' an710021,China )Abstract : Based on the comparison of light transmittance, mechanical strength and chemicalstabilityofseveralnaturalpolymermaterialsandtheircomposites ,theoptimalmaterialwasselectedasthecarrierofphotosyntheticbacteriaimmobilization ,andtheimmobilizationcon- ditions wereoptimized.Theresultsshowedthattheperformanceofimmobilizedparticlespreparedby mixing2% agarand2% carrageenanataratioof1:1 wasthebest.The most suitableimmobilizationconditionswerefixedin2% KClfor60 minutes ,and40 mLofbacte-riawereembeddedin6mLofcarrier.Subsequently ,agar-carrageenanwasusedtoimmobilize第2期陈朵等：固定化光合细菌转化预水解液（PHL）的制氢研究•17•photosynthetic bacteria to form microspheres and the hydrogen production performance was analyzed in a simulated pre-hydrolyzed solution(PHL).The results showed that the hydrogen production of the second cycle was1.8times that of the first cycle,the utilization rate of xylose and the degradation rate of phenol were up to99.4%and28.5%,respectively,and the pH of the system was relatively stable.The immobilized photosynthetic bacteria can still maintain high hydrogen production performance in six cycles,indicating that the immobilized microspheres have stable reusability and have good application prospects.Key words:agar-carrageenan；photosynthetic bacteria;immobilizition；pre-hydrolysate;hydrogenproduction0引言溶解浆厂是木质纤维素的主要利用者之一⑴,基于生物质精炼的原则在硫酸盐法制浆前需对其进行预水解处理，以抽出原料中的半纤维素［2］,因此就如何充分对预水解液中的半纤维素高值化利用已成为当前生物质精炼的热点目前，对半纤维素的利用主要集中在发酵制取乙醇、乙酸、糠醛和木糖醇等物质［12］.但是，普遍存在底物转化效率低的问题，主要原因是预处理过程产生的糖类或木素在高温和酸性条件下转化为乙酸、糠醛及酚类等物质［5'6］,这些抑制剂对微生物的生长存在严重的抑制作用.利用光合细菌处理预水解液目前尚未见报道，由于光合细菌具有灵活的代谢方式和较高的底物适应性和耐受性［7］,其可以利用预水解液中木糖和乙酸等主要碳源，在废水去污的同时实现了有机物的能源转化.Jiaqi Chen等8对光合细菌处理废水的应用范围、生物降解途径以及生物反应器模型进行了综述，提出以光合细菌为基础的技术是满足废水处理可持续发展的潜在替代方法.本课题组⑹前期对光合细菌转化秸秆解聚液的制氢特性进行了研究，发现光合细菌利用水解液具有很好的产氢潜力，最大产氢量为3944.2mL/L,且反应迟滞时间相对较短.Walailak Pattanamanee等［0］选用葡萄糖、木糖和醋酸为主要成分进行混合碳源光发酵产氢的研究，发现在使用水解产物进行光发酵制氢时，气体产量高度依赖于混合碳基质的组成.以上研究结果均表明预水解液作为光合细菌产氢底物的有效可行性.在预水解液作为底物时，为了克服预水解液中抑制剂的问题，需进行发酵前脱毒处理，常用的方法如离子交换［2,1］或灰碱处理⑶等，但是既增加了成本也造成了可利用糖分的损失［12］.固定化微生物技术以其为微生物提供更多的保护、简单的细胞活化和良好的操作稳定性［3］等优势引起研究者的广泛关注.但是在选择固定化材料时，需满足无毒、简单易得和物化性能稳定等条件［14］.以下三种材料海藻酸钠、琼脂和卡拉胶均为来源于大自然的生物大分子，对微生物无毒性.海藻酸钠是从褐藻或马尾藻中提取碘和甘露醇之后的副产物，当遇到Ca2+时会形成水凝胶，其网络互传结构使其具有良好的成球性和稳定性［15］；琼脂是从海藻中提取的多糖体［16］,因其较高的稳定性和良好的生物亲和性被视为固定化的理想载体；卡拉胶是从藻类提取出的一种天然凝固剂，具有很好的透明度和稳定性［17］.用这三种材料对光合细菌进行固定化，成本较低且操作易行.本文以光合细菌HY01为目标菌株，通过几种天然高分子聚合材料及其复合物的透光性、化学稳定性等性能的比较，遴选出最佳的光合细菌固定化包埋载体，并对其固定化条件进行优化.之后对固定化的光合细菌在模拟预水解液中进行产氢特性分析，分析固定化细菌的产氢性能、对碳源的利用能力、对毒性物质的耐受性以及其循环特性.固定化光和细菌转化预水解液制氢不仅实现了光发酵一步法转化制氢，而且为预水解液的高值化利用提供了新的途径.1实验部分1.1实验菌株和培养条件1.1.1实验菌株实验使用的光发酵产氢菌株球形红细菌Rhodobacter sphaeroides HY01为实验室保藏菌种.1.1.2培养条件（1）MPYE生长培养基（/L）：CaCl1g, MgCl1.6g,酵母提取物3g,鱼粉蛋白胨3g.（2）MedA产氢培养基（/L）：D木糖6g,L-谷氨・18・陕西科技大学学报第39卷酸1.25g,10%NaCl10mL,氮川三乙酸10g,CaCl23.33g,MgSO4・7H2O29.5g,(NH4)6Mo7O24・4H2O93mg,FeSO4・7H2O99mg,微量元素溶液20mL,溶液灭菌后用微孔滤膜加入维生素溶液10mL,磷酸盐缓冲溶液20mL.(3)模拟预水解液的组成(/L)：木糖、乙酸和苯酚碳的摩尔质量分别为162.5mmok25mmol 和125mmol.1.2实验菌株和培养条件1. 2.1光合细菌的活化与富集在一80C低温储存箱中取出冻存液，通过双层平板划线法，用纯木质接种棒蘸取冻存液进行平板划线，在恒温培养箱中培养72h,挑取平板上的单菌落接种至25mL的MPYE生长培养液中，将离心管置于30C,200rpm恒温摇床中富集培养,培养至对数生长期取出，调节菌液吸光度OD600=0.8士0.02,离心收集菌体备用.1. 2.2固定化载体的制备与选择分别配备海藻酸钠、琼脂、卡拉胶凝胶，用注射器缓慢吸取凝胶，避免产生气泡，悬空滴加到交联剂中形成小球即为载体的制备•固定好的小球用磷酸盐缓冲溶液冲洗三遍•对固定化载体进行透光性、机械强度和重复性等性能评判，综合选择最佳的固定化载体.1. 2.3固定化光合细菌微球的优化和产氢设置琼脂-卡拉胶不同的体积比例：2:4、2.5：3.5、3：335： 2.5、4：2；不同的交联剂浓度: 1%、2%、3%、4%；不同的细菌接种量：10mL、20 mL、30mL、40mL、50mL；不同的固定化时间:30 min、60min、90min、120min,来探究光合细菌固定化时的最佳条件.1.3分析方法采用比浊法对培养液中的生物量进行测定(OD600)；固定化颗粒的透光性参考张念一等［8］的方法，采用拉压力测试仪测定固定化载体的机械强度；DNS法［9］测定培养液中还原糖的含量；4-氨基安替比邻比色法来测定苯酚的含量［0］.所有实验均设置三个平行样.2结果与讨论2.1光合细菌固定化载体SEM形貌特征分别采用海藻酸钠、琼脂粉、卡拉胶、海藻酸钠-琼脂和琼脂-卡拉胶制作固定化小球,其SEM 形貌如图1所示.(a)海藻酸钠载体(f)海藻酸钠固定的HY01(b)琼脂载体(g)琼脂固定的HY01(d)海-琼复合载体(i)海-琼固定的HY01(e)琼-卡复合载体(j)琼-卡固定的HY01不同材料及其固定化HY01的SEM图图1图1(a)〜(e)表示没有负载细菌时固定化载体.可以看出，海藻酸钠(如图1(a)所示)的形貌为较为细小的丝网状结构，但是形态结构不太规则；琼脂(如图1(b)所示)的结构为较为规则的层状结构，并且表面光滑，但光滑的表面会减少细菌的附着点；卡拉胶(如图1(c)所示)具有网状结构的形貌,网孔大小从100毺m到400毺m不等；海藻酸钠-琼脂复合固定化载体(如图1(d)所示)和单一琼脂的表面结构相比，加入海藻酸钠后，琼脂表面变得粗糙但仍保持其原有的结构；从图1(e)可以明显地看出，琼脂-卡拉胶固定化载体同时具备琼脂的层状规则孔隙和卡拉胶的网状结构，卡拉胶的添加，缩小琼脂层状大孔结构的同时，也为细菌的固定化提供了更大的比表面积•图1(f)〜(j)表示固定化载体上的光合细菌分布情况•五种不同固定化载体的细菌分布具有很明第2期陈朵等：固定化光合细菌转化预水解液(PHL)的制氢研究・19・显的差异，琼脂凝胶上的光合细菌(如图1(g)所示)数量明显少于其他几种固定化载体，原因是琼脂的结构特点造成了细菌有较为严重的泄露；光合细菌在海藻酸钠中(如图1(f)所示)虽然可以稳定的生长增殖，但是其自身对pH的敏感性［1］导致在循环利用时便会出现颗粒变软甚至破碎的现象,这将对固定化实验带来很不利的影响；海藻酸钠-琼脂固定的光合细菌(如图1⑴所示)出现明显的分布不均现象；琼脂和卡拉胶固定化载体(如图1 (j)所示)使得光合细菌均匀的固定于载体当中，是固定化载体的良好选择.2.2光合细菌固定化包埋载体的选择对于光合细菌来说，理想的固定化载体应该是具有无毒性、良好的透光性、较高的机械强度以及优良的可循环利用性等优点［2］.以木糖为唯一碳源时，固定化光和细菌的产氢结果如图2所示.实验结果可知，海藻酸钠和卡拉胶作为固定化载体时产氢量相近，但是随着时间的延长，小球的形态会变得疏松甚至破碎，说明可循环性较差.琼脂作为固定化载体时表现出良好的产氢性能，但游离的细菌对产氢量贡献较大.还观察到琼脂和卡拉胶混合后固定化细菌的产氢量和重复稳定性明显优于二者单独固定时性能.复合材料作为载体时通过键的断裂和结合或物理作用使得新的材料具有更好的机械性能和循环稳定性［3］・图3为不同载体固定化小球的机械强度测试琼脂凝胶具有足够大的机械强度，可达6.8N；卡拉胶在单独作为固定化载体时机械强度较低，当琼脂和卡拉胶复合之后的机械强度界于二者单独使用时之间•图4表示固定化小球的透光性测试，良好的透光性有助于光合细菌增加传质效率，卡拉胶的透光性明显大于其他载体材料，同时还发现，琼脂和卡拉胶复合之后的透光性比琼脂提高了 2.8倍.由于各类废水的化学条件都比较复杂，对不同材料固定化小球的化学稳定性进行测试如表1所示，当固定化小球在酸性和盐性环境中停留4h之后，海藻酸钠小球会变得易碎且结构松散；琼脂-卡拉胶复合的化学稳定性比较稳定.综合比较而言,卡拉胶具有良好的透光性，并且化学稳定性适中;琼脂作为固定化载体时化学稳定性较好，且在循环使用中表现出稳定的产氢性能；鉴于二者的优点,将琼脂和卡拉胶复合作为固定化材料时，不仅解决了琼脂透光性较差的缺陷同时，还减少细菌的泄露，而且复合材料固定化光合细菌体现出了较强的产氢性能和稳疋的循环利用性.ooooooOooooooO5555332211'uoppnpojdu①mojpah1st2nd3rd4th2图SA Agar Car Agar+SA Agar+CarThe carrier for immobilization不同材料化固定HY01的产氢结果图87654321Agar Car SA+Agar Car+Agar[]Mechanical Strength3图不同固定化材料的机械强度The carrier for immobilizationSA Agar Car SA+Agar Car+AgarThe carrier for immobilization图4不同固定化材料的透光率表1固定化材料的化学稳定性比较载体HCl NaOH NaCl Na2HPO4SA-0----Agar0+0+Car--++++ SA+Agar0--0Car+Agar-++++注：“一一”表示颗粒结构松散，易碎；“一”表示颗粒略变软，弹性下降；“0”表示颗粒未发生明显变化；“+”表示颗粒变硬，强度增加.2.3光合细菌固定化条件的优化以琼脂-卡拉胶为固定化载体，对其最佳的固定化条件进行优化，结果如图5所示.实验操作为:・20・陕西科技大学学报第39卷将离心收集好的菌体加入到浓度分别为2%的琼脂-卡拉胶的混合凝胶中(共6mL),采用涡旋仪震荡混合均匀，用注射器缓慢吸取5mL,避免产生气泡，滴加小球到KCl交联剂中固定化，固定化之后的微球用磷酸盐缓冲溶液冲洗三遍，产氢反应在50mL注射器中进行.选择细菌接种量、固定化时间、交联剂浓度和琼脂-卡拉胶的配比进行实验，最终确定最佳的固定化条件•2. 3.1接种量对固定化产氢的影响取OD660为0.8士0.02的菌液离心后与琼脂-卡拉胶凝胶混合均匀，制作小球进行产氢.如图5 (a)所示，当接种量过低时，光合细菌生长缓慢，导致产氢量较低；而当接种量为50mL时，细菌在培养基中对营养物质进行竞争•因此，选用40mL的细菌接种量进行实验.2. 3.2固定化时间对固定化产氢的影响固定化时间对固定化载体的强度和细菌活力都会产生影响，固定化时间太短可能会导致载体强度不够、容易破碎、细菌容易泄露；固定化时间过长使凝胶结构太致密，不利于细菌对底物的利用[4]・从图5(b)可以看出，固定化时间对产氢量的影响不是很大,但是随着固定化时间的延长，产氢量出现先上升后下降的趋势，且在固定化时间为60 min的时产氢量最高•因此选取60min为后续实验的固定化时间•2.3.3交联剂浓度对固定化产氢的影响毷型卡拉胶由于结构单元富含硫酸酯键一O—SO厂，因此可与交联剂KCl中的K+共价结合形成结构稳定的凝胶,K+浓度对固定化载体的强度和细菌的活性会产生较大的影响[4].如图5(c)所示，当KCl 浓度较低时，产氢量较低，因为制备的固定化载体结构不稳定，容易破裂•当交联剂浓度过高时，产氢量出现快速下降,是因为固定化载体的结构比较致密，传质性能变差;另外过高的K+浓度可能会导致细菌的细胞膜内外出现浓度差,会对细菌造成伤害.因此最终选择交联剂浓度为2%.2. 3.4琼脂-卡拉胶配比对固定化产氢的影响图5(d)为琼脂和卡拉胶在不同配比下固定化光合细菌的产氢量对比，当卡拉胶比例过高时(2:4)产氢量明显降低.过多的卡拉胶对琼脂形成了包覆作用，再加以KCl的交联作用使得载体表面形成了坚硬的包覆膜，严重影响了细菌的生长和底物的传质性能•当琼脂配比过高时(4:2),在产氢的体系中有较高的细菌浓度，说明细菌有明显的泄露•因此选择3:3的配比进行后续实验•O004旦'uoppnpojduebnOHPAH0053300(00520020015010000o10203040Bacterial load/mL(a)细菌接种量50OOOOOOOOOOOOOOOO55554332211目'uoppnpojdu①UOHPAH壬壬(b)固定化时间o*_―――306090120Time/min旦'UOHunpoJduebnOJPAH(d)琼脂-卡拉胶配比图5光合细菌固定化产氢条件的优化2.4木糖和苯酚混合物作为碳源时固定化细菌的产氢性能第 2 期陈朵等：固定化光合细菌转化预水解液(PHL)的制氢研究・21・在硫酸盐预水解液中存在少量的酚类物质(约1〜2 g/L)[4],通常用苯酚作为模型化合物来替代酚类物质•前期实验得知游离光合细菌对苯酚的耐受阈值为500 mg/L,因此选用500 mg/L 的苯酚与木糖作为双碳源进行产氢性能的探究•如图6所示，初期光合细菌对底物的利用受到传质效率等因素的限制，基质不能达到固定化小球内部[5],导致产氢量较低，苯酚和木糖的利用效果不明显•然而,在2〜4次循环产氢时，产氢量有明显的提升，第二次的累积产氢量可达到3 463. 2 mL/L,木糖利用率(95. 7%)和苯酚降解率(24. 3%)也达到最大值.可见固定化的光合细菌对产氢基质有很好的适应性和利用性，并且重复使用6次后产氢量为2 230. 8mL/L,具有很好的稳定性.相比于游离态细菌产氢(pH = 5. 9),固定化之后的细菌的对系统的pH 有更大的适应范围(pH = 4. 88),此结论与孙丽慧等[5]的实验发现相一致•OOP 53态在光合细菌加入之后变得粗糙•图7(d)是在模拟PHL 中产氢反应两个循环周期后的固定化微球的断面图图像，可以看出长时间的培养产氢使细胞显著生长，从而占据了整个微球的内表面，这表明细菌在微球内具有很高的生物附着量.(d)(a)琼脂-卡拉胶微球的形貌图(b)琼脂-卡拉胶微球的断面结构(c)琼脂-卡拉胶微球负载细菌后断面结构(d)循环2次后断面图(e)细菌的分布图图7 固定化细菌微球的SEM 图旦、u.24unpoJdue b£)OJPAHOOF 300OOF 250OOF 200150looOOF5B2. 6 模拟PHL 为碳源时的产氢性能图8(a)〜(e)分别表示固定化光合细菌在PHL 中的累计产氢量、末端pH 值、溶液中的游离细菌浓度、苯酚和木糖利用率的对比图•(a)以木糖-苯酚为碳源时固定化细菌的产氢量和pH 值L I 30L I52L I20L I1584*1 84*284*3 84*484*5 84*6Cycle(b)木糖和苯酚混合碳源时底物的利用率图6 木糖-苯酚为碳源时固定化细菌的产氢性能-★- Phenol —0—Xylose乞、oU O R e p e ^e p O S O I A X908070602. 5 固定化光合细菌利用PHL 产氢SEM 图以固定的琼脂-卡拉胶微球为研究对象，对其进行电镜扫描如图7所示.从图7(a)〜(c)可以观察到，琼脂-卡拉胶微球直径约4 mm ；未固定光合细菌的琼脂-卡拉胶凝胶珠表面光滑，这些交联形(a)产氢量(b)产氢结束培养液的pH 值(c)游离细菌浓度(d)苯酚利用率(e)木糖利用率图8 以模拟PHL 为碳源时固定化细菌的产氢性能L一、①l e A O U I①.io u ① qd・22・陕西科技大学学报第39卷首先，与游离态光合细菌利用PHL产氢相比，初始固定化的细菌不如游离态时的产氢量大(6420.6mL/L),但在重复第二次实验时，产氢量要大于游离状态，并且第三次和第四次重复时仍然表现出较为稳定的产氢性能(如图8(a)所示)；其次，发酵产氢末端的pH值维持在6.3—6.4(如图 8(b)所示)，产氢量的增加与产氢过程中培养液的pH值较为稳定有很大的关系.在PHL产氢系统中，除了木糖作为主要碳源之外，还存在一定的小分子酸，乙酸的转化利用会提高系统的pH,两种碳源的协同作用让产氢系统更稳定，产氢周期更长，产氢量更大;值得一提的是系统中苯酚的去除率最大可达到2&5%,木糖利用率相对比较稳定,基本上都在95%以上(如图8(d)和8(e)所示)；最后，对产氢结束的细菌浓度进行测量，可以看出在整个循环过程中细菌泄露量较少(如图8(c)所示)，说明所制备的固定化载体具有很好的循环使用性能，具有很好的应用前景.3结论本文通过比较不同天然高分子聚合物固定化材料海藻酸钠、琼脂、卡拉胶等作为载体来固定光合细菌，从细菌的生长适应性、透光性、机械强度和稳定性等方面确定了最佳的固定化材料为琼脂-卡拉胶，而后通过条件优化得出最佳固定化条件.并研究了木糖和500mg/L苯酚作为底物时的产氢性能，重复六个周期都具有比较稳定的产氢性能,且固定化细菌和游离态细菌相比对苯酚的耐受性有明显提升.最后，对固定化光合细菌在模拟PHL中的产氢性能进行研究，得知木糖利用率可达99.4%,苯酚降解率为2&5%,并且预水解液中的复合碳源对系统的pH具有自平衡作用是产氢性能提高的另一个原因.固定化光合细菌转化预水解液制氢不仅实现了光发酵一步法制氢，而且为预水解液的高值化利用提供了一定的理论基础.参考文献[1]YangS,WenY,Zhang H,etal.Enhancingthefockreac-tivityofdissolvingpulpbythecombinedprerefiningandpolydimethyldia l ylammoniumchloride-assistedce l ulasetreatment[J].BioresourceTechnology,2018,260(6):135-140.[2]ShenJ,KaurI,Baktash M M,etal.Acombinedprocessofactivatedcarbonadsorption,ionexchangeresintreatmentand membraneconcentrationforrecoveryofdissolvedor-ganicsin pre-hydrolysisliquorofthekraft-based 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DevelopmentandAp...

Development and Application of an Off-LineSPE–LC–UV Methodology for theDetermination of Penoxsulam in AquaticSystems Adjacent to Rice FieldsAnabela Cachada1,&,Catarina Marques2,Ruth Pereira2,Fernando Gonc¸alves2,Armando C.Duarte1 1Department of Chemistry and CESAM,University of Aveiro,3810-193Aveiro,Portugal;E-Mail:**************2Department of Biology and CESAM,University of Aveiro,3810-193Aveiro,PortugalReceived:15June2009/Revised:8September2009/Accepted:16November2009Online publication:25December2009AbstractAn accurate,simple,reproducible and sensitive off-line SPE–LC–UV method was developedand validated for the determination of penoxsulam,a new triazolopyrimidine sulphonamideherbicide widely used in rice culture.The method was validated in terms of precision,line-arity,detection limit,quantiﬁcation limit and accuracy.The repeatability and intermediateprecision of LC–UV conditions chosen were evaluated,with an RSD always bellow10%.Alimit of detection of0.07l g L-1was achieved after SPE concentration.Recovery studies,performed in two different matrixes(run-off water from riceﬁelds and brackish water),ranged from93to105%.The methodology was successfully used to detect penoxsulam inaquatic systems,during an application period in riceﬁelds.KeywordsColumn liquid chromatographySolid phase extractionUV detectionStyrene-based polymerSurface waterPenoxsulamIntroductionPenoxsulam,is a new triazolopyrimidine sulphonanilide herbicide,commercial-ized with trade names‘‘Granite’’,‘‘Grasp’’,‘‘Galleon SC’’or‘‘Viper’’and manufactured by Dow AgroSciencesLLC[1,2].It has been widely used as afoliar spray in rice culture,for the controlof annual grasses,broadleaf weeds andsedges,normally as a postemergenceherbicide.It is water soluble,very mobile,hydrolytically stable and nonvolatile,with degradation half lives in the aquaticsystem ranging between2and13days[1–4].It is suspected to pose a potentialrisk for aquatic and terrestrial plants aswell as for microbial communities[1,2].Nevertheless,its environmental fate andthe impacts of long-term aqueous expo-sures have not yet been completely char-acterized[1,4,5].Regarding the analysisof penoxsulam in environmental ma-trixes,there is no reference method,butthe most frequently used is the DowAgroSiences analytical method GRM01.30LC–MS–MS[3].Other methods weredeveloped[6]although most of them onlytested fortiﬁed freshwaters[2,4,5].Thedevelopment of simple analytical meth-ods using conventional detectors,such asthe UV,for reliable quantiﬁcation overseveral orders of magnitude is thereforevery important.The main diﬃculties inanalysis of penoxsulam regard its highpolarity as well as the complexity of somematrixes,such as water containing highconcentrations of dissolved organic mat-ter.In addition,sensitive methods areneeded in order to reach the low moni-toring levels requested by the EU WaterFramework Directive[7].The introduc-tion of SPE as an extraction techniqueallowed achieving those levels,even whenusing low sensitive detectors such asUV.2010,71,347–350This work describes a method based on oﬀ-line SPE–LC–UV to determine penoxsulam in agricultural drainage and brackish water.Parameters such as cali-bration linearity,limits of detection and quantiﬁcation,precision and accuracy, were investigated.Finally,the concen-tration of penoxsulam inﬁeld samples was monitored.ExperimentalChemicalsAcetonitrile(ACN)(LC grade)waspurchased from Labscan and acetic acid(100%)from Merck.Only ultra purewater freshly produced by a MilliporeMilli-Q system was used in all analyticalexperiments.Mobile phases wereﬁlteredunder vacuum through a0.2l m poly-amide membraneﬁlter(Whatman)anddegasiﬁed in an ultrasonic bath.Penoxsulam(2-(2,2-diﬂuoroethoxy)-N-(5,8-dimethoxy[1,2,4]triazolo[1,5-c]pyrimi-din-2yl)-6-(triﬂuoromethyl)bezenesulfona-mide)was kindly provided by DowAgroSciences LLC(analytical grade,ref.TSN104882).A stock standard solution(100mg L-1)was prepared in ACN andstored at-18°C.Calibration standardswere prepared by dilution of the stocksolution with the mobile phase,in con-centrations of0.10,0.25,0.50,0.75and1.0mg L-1.The sorbent used was astyrene-based polymer,Sepra SDB-L(95l m,255A,bulk sorbent),purchasedfrom Phenomenex.InstrumentationThe analytical instrumentation includedan LC Jasco model with a Rheodyne7125injector and a loop size of50l Lcoupled to a fast scanning UV detector(UV Chrom-A-Scope,BarSpec)operat-ing between190and370nm.Acquisi-tion was performed at205nm andstarted at5min until12min.The ana-lytical column used was a Supelcosil LC-8(15094.6m,5l m,120A),with aguard column of the same material.Chromatographic ConditionsThe temperature of the analytical col-umn was set to30°C.The mobile phaseselected consisted of water acidiﬁed with0.01%of acetic acid and40%of ACN ataﬂow rate of1mL min-1.In order toclean-up the column between samples,an elution gradient was used:100%ofmobile phase from0to12min,100%ACN at15min(during2min)andagain100%of mobile phase at18min.Each standard was injected twice andcalibration curves were constructedevery day.Quantiﬁcation was performedby external calibration by measuring thepeak areas.The LOD was calculatedbased upon an S/N ratio of3:1,whereasthe LOQ was calculated based upon anS/N ratio of10:1.In order to assure thecorrect identiﬁcation of the compoundthree techniques were used:co-chroma-tography(samples spiked with increas-ing amounts of standard and injected tothe LC system),peak spectrum(by usinga fast scanning UV detector)and reten-tion time comparison to those of thestandards.Water Samples ExtractionProcedureSamples wereﬁltered through a0.45l mnylon membrane(from Whatman)andextracted by SPE.Cartridges containing500mg of Sepra SDB-L sorbent werepreviously rinsed with4mL of methanoland conditioned with4mL of water.1Lof sample was then passed though thecartridge,via a vacuum manifold at10mL min-1.After loading the sampleinto the SPE cartridge,it was washed with4mL of methanol:water(5:95)and driedunder vacuum for30min.The herbicidewas eluted with5mL of ACN containing0.1%of acetic acid.The eluate was evap-orated to dryness by means of a rotaryevaporator(40°C),dissolved in3mL ofACN,transferred to a vial and thenevaporated again to dryness under a gen-tle stream of nitrogen.The residue wasthen redissolved in250l L of mobilephase and injected into the LC instrument.Results and DiscussionChoice of AnalyticalConditions for LC–UVSeveral mobile phases(water acidiﬁedwith formic acid or acetic acid,withdiﬀerent proportions of ACN)and dif-ferent solvents for sample dissolution(ACN,50%ACN and mobile phase) were tested,using a standard of0.5mg L-1.The selection of mobile phase and samples dissolution was based on optimal peak shape.Figure1a shows the chromatogram of a standard using the selected conditions.The choice of the optimum wavelength for acquisi-tion(205nm),was based on the peak spectrum(Fig.1c).The precision of the method was examined by carrying out a repeatabilityand an intermediate precision study at three levels of concentration(0.25,0.75 and1.0mg L-1),with three consecutive injections during the same day and on three diﬀerent days.Results presented in Table1show that the method is repeat-able for the same day and in day-to-day injections but,as observed in other works [8],RSD increases in the latter.Calibration curve was obtained by injecting each standard(n=5)three times.Good linearity was observed over the range tested(Table1),and the determination coeﬃcient(r2)was always higher than0.9958(p<0.05).Table1 also shows other calibration parameters such as calibration equation,standard deviation of residuals(Sy/x),LOD (0.06mg L-1)and LOQ(0.20mg L-1). Water Samples ExtractionThe choice of extraction procedure(sor-bent used,pH,elution solvents)was based on previous studies performed with polar pesticides[4,8–12].In order to study the eﬀect of SPE on the analysis of penoxsu-lam,a calibration curve was constructed by analysingﬁve calibration levels of fortiﬁed MQ water.Therefore,1L of spiked MQ water,with concentrations ranging from0.025to0.25l g L-1was extracted,and concentrated to250l L. The calibration curve obtained after pre-concentration using the selected method (Y=(39,421±2,051)X,r2=0.996) does not diﬀer(t test,p=0.255)from the one presented in Table1,meaning that the SPE procedure is not aﬀecting the determination of penoxsulam.The LOD and LOQ in water samples before pre-concentration was evaluated as0.02and 0.07l g L-1,respectively.Hence,this method can be considered very sensitive[3,6].Figures of Merit of theAnalytical ProcedureThe method was further evaluated for itsaccuracy and precision by analyzingspiked samples collected in a canalreceiving drainage water from riceﬁeldsand in a nearby estuary.Spikes wereprepared at three levels(0.1,0.5,2l gL-1),allowed to equilibrate for2h[12]and extracted.The method was accurateand precise,with the mean recovery(n=3)of penoxsulam obtained for theagricultural drainage water ranging from98(for0.5and2l g L-1)to105%(for0.1l g L-1).The RSD was below10%for all three levels:2%for0.1l g L-1;8%for0.5l g L-1;and5%for2l g L-1.The recoveries for brackish water rangedfrom93(for0.5and2l g L-1)to101%(for0.1l g L-1),and the RSDs were3,5and4%respectively.No interference was observed whenanalyzing control blanks and controlﬁeld samples in both types of samples(Fig.1b shows the chromatograms foragricultural drainage water).The slopingbaseline observed inﬁeld samples(Fig.1b)is most likely due to the pres-ence of humic acids in a high level as aresult of the concentration factor ob-tained.Besides,as shown in Fig.1c,theUV spectrum at the speciﬁc retentiontime of penoxsulam did not show anyinterference.The increase of absorbanceat higher wavelengths may be due to thepresence of compounds with higheraromaticity and complexity such ashumic like substances.Application of the AnalyticalProcedures and LimitationsIn order to verify the applicability of theanalytical procedure in real environ-mental samples,agricultural drainagewater samples were collected during theapplication period of penoxsulam.Sam-ples were collected from one location,before(day0)and over7days after thebeginning of applications.A relative highrange of concentrations was observed:from non-detectable levels(before appli-cation)to2.3l g L-1(6th day).It waspossible to verify the existence of twopulses of application,on day1(0.36l g L-1)and day6,and a quickdecrease of concentrations observed inthe following days(0.10l g L-1on day4and0.8l g L-1on day7).ConclusionsThis method allows the quantiﬁcation oflow concentrations(LOQ=0.07l gL-1)of penoxsulam in agricultural run-oﬀwater and brackish water.Themethod described is precise(RSD rang-ing from2to8%)and accurate(recov-eries between93and105%).Thediﬃculty of attribution of the chro-matographic peak to penoxsulam can bepartially overcome by comparing the UVspectra of samples with the UV spectraof pure penoxsulam.SPE–LC–UV is asimple,cheap and robust method whichallows achieving low monitoring levelsby pre-concentration of samples.Thismethod can therefore be used as analternative for monitoring purposes andfor studies of penoxsulam behaviour inthe aquatic environment.Table1.Results of the repeatability study in terms of retention time(RT),area,and calibration parametersRT(min)Intra-dayprecison a(RSD%)Day-to-dayprecision a(RSD%)Calibrationcurver2Sy/x LOD(mg L-1)LOQ(mg L-1) RT Area RT Area8.630.85 1.4 5.18.3Y=(40,919±2,245)X0.99581,1280.060.20a Data given for0.25mg L-1AcknowledgmentsThis work was supported by FCT (Fundac a o para a Cie ncia e Tecnologia), through a PhD grant attributed to A. Cachada(SFRH/BD/38418/2007),and by CESAM.The authors would like to thank Dow AgroSciences LLC for kindly providing the penoxsulam ana-lytical standard.ReferencesEPA(United States EnvironmentalProtection Agency)(2004)Pesticide factsheet:penoxsulam.Oﬃce of Prevention,Pesticides and Toxic Substances(7501C),Washington,USA2.Jabusch TW,Tjeerdema RS(2005)JAgric Food Chem53:7179–7183.doi:10.1021/jf050767g3.Roberts DW,Knuteson JA,Jackson R(2003)In:Pesticide in air,plant,soil,&water system.Proceedings of the XIISymposium pesticides chemistry.Piacen-za,Italy,pp.349–3574.Jabusch TW,Tjeerdema RS(2006)JAgric Food Chem54:5962–59675.Koschnick TJ,Netherland MD,HallerWTJ(2007)J Aquat Plant Manag45:47–516.Rubio DR,Kamp LM,Heilman M,Williams L,Rubio FM(2008)J AgricFood Chem56:7606–7612.doi:10.1021/jf80102737.EC(European Commission)(2000)Directive2000/60/EC of the EuropeanParliament and of the Council of23October2000establishing a frameworkfor community action in theﬁeld of waterpolicy.OJ L327,pp1–728.Rodrıguez-Delgado MA,Herna ndez-Borges J(2007)J Sep Sci30:8–14.doi:10.1002/jssc.2006002719.Thorstensen CW,Lode O,ChristiansenAL(2000)J Agric Food Chem48:5829–583.doi:0.1021/jf000012410.Quintana J,Marti I,Ventura FJ(2001)J Chromatogr A938:3–1311.Tran ATK,Hyne RV,Doble P(2007)Chemosphere67:944–995.doi:10.1016/j.chemosphere.2006.11.002gana A,Bacaloni A,De Leva I,FaberiA,Fago G,Marino A(2002)Anal ChimActa462:187–198。

木本植物应对干旱胁迫的响应机制：基于水力学性状视角

第４４卷第７期２０２４年４月生态学报ＡＣＴＡＥＣＯＬＯＧＩＣＡＳＩＮＩＣＡＶｏｌ．４４，Ｎｏ．７Ａｐｒ．，２０２４基金项目：国家自然科学基金项目（３２０７１８４５）；甘肃省科技计划资助（２３ＪＲＲＡ５７２）；内蒙古自治区科技重大专项（２０２１ＺＤ００１５）；甘肃省科技计划资助（２３ＪＲＲＡ６７１）收稿日期：２０２３⁃０５⁃２０；㊀㊀网络出版日期：２０２４⁃０１⁃１２∗通讯作者Ｃｏｒｒｅｓｐｏｎｄｉｎｇａｕｔｈｏｒ．Ｅ⁃ｍａｉｌ：ｌｉｙｌ＠ｌｚｂ．ａｃ．ｃｎＤＯＩ：１０．２０１０３／ｊ．ｓｔｘｂ．２０２３０５２０１０６５程莉，李玉霖，宁志英，杨红玲，詹瑾，姚博．木本植物应对干旱胁迫的响应机制：基于水力学性状视角．生态学报，２０２４，４４（７）：２６８８⁃２７０５．ＣｈｅｎｇＬ，ＬｉＹＬ，ＮｉｎｇＺＹ，ＹａｎｇＨＬ，ＺｈａｎＪ，ＹａｏＢ．Ｒｅｓｐｏｎｓｅｍｅｃｈａｎｉｓｍｓｏｆｗｏｏｄｙｐｌａｎｔｓｔｏｄｒｏｕｇｈｔｓｔｒｅｓｓ：ａｒｅｖｉｅｗｂａｓｅｄｏｎｐｌａｎｔｈｙｄｒａｕｌｉｃｔｒａｉｔｓ．ＡｃｔａＥｃｏｌｏｇｉｃａＳｉｎｉｃａ，２０２４，４４（７）：２６８８⁃２７０５．木本植物应对干旱胁迫的响应机制：基于水力学性状视角程㊀莉１，２，李玉霖１，２，３，∗，宁志英１，２，杨红玲１，２，詹㊀瑾１，２，姚㊀博１，２１中国科学院西北生态环境资源研究院，兰州㊀７３００００２中国科学院大学，北京㊀１０００４９３中国科学院西北生态环境资源研究院奈曼沙漠化研究站，通辽㊀０２８３００摘要：干旱最显著的影响表现在区域尺度的森林死亡事件中，可以在短时间内杀死数百万棵树木㊂鉴于未来极端干旱事件的频率和强度可能随温度的升高而增加，迫切需要明确树木对干旱胁迫的响应对策以及衰退死亡机理，揭示木本植物在干旱环境中存活和死亡的生理机制，了解树木在未来气候下的适应机制，提高预测树木对干旱反应的准确性㊂在常用植物功能性状的基础上，重点纳入与植物水分运输能力及耐旱性相关的水力学性状，系统总结了：１）植物木质部水分运输的物理机制；２）植物应对干旱胁迫的水力响应过程：３）干旱胁迫下木本植物水分利用对策；以及４）干旱胁迫下木本植物衰退／死亡机理㊂最后，提出３个尚待解决的主要问题：１）加强纳入水力性状阐明植物对干旱胁迫的响应和调节机制；２）加强从全株植物的角度考虑植物不同组织性状间的关系；３）深入探究树木干旱致死机理㊂关键词：木本植物；干旱胁迫；水力性状；水分运输策略；干旱致死机理Ｒｅｓｐｏｎｓｅｍｅｃｈａｎｉｓｍｓｏｆｗｏｏｄｙｐｌａｎｔｓｔｏｄｒｏｕｇｈｔｓｔｒｅｓｓ：ａｒｅｖｉｅｗｂａｓｅｄｏｎｐｌａｎｔｈｙｄｒａｕｌｉｃｔｒａｉｔｓＣＨＥＮＧＬｉ１，２，ＬＩＹｕｌｉｎ１，２，３，∗，ＮＩＮＧＺｈｉｙｉｎｇ１，２，ＹＡＮＧＨｏｎｇｌｉｎｇ１，２，ＺＨＡＮＪｉｎ１，２，ＹＡＯＢｏ１，２１ＮｏｒｔｈｗｅｓｔＩｎｓｔｉｔｕｔｅｏｆＥｃｏ⁃ＥｎｖｉｒｏｎｍｅｎｔａｎｄＲｅｓｏｕｒｃｅｓ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｌａｎｚｈｏｕ７３００００，Ｃｈｉｎａ２ＵｎｉｖｅｒｓｉｔｙｏｆＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｂｅｉｊｉｎｇ１０００４９，Ｃｈｉｎａ３ＮａｉｍａｎＤｅｓｅｒｔｉｆｉｃａｔｉｏｎＲｅｓｅａｒｃｈＳｔａｔｉｏｎ，ＮｏｒｔｈｗｅｓｔＩｎｓｔｉｔｕｔｅｏｆＥｃｏ⁃ＥｎｖｉｒｏｎｍｅｎｔａｎｄＲｅｓｏｕｒｃｅｓ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｔｏｎｇｌｉａｏ０２８３００，ＣｈｉｎａＡｂｓｔｒａｃｔ：Ｔｈｅｍｏｓｔｎｏｔａｂｌｅｅｆｆｅｃｔｓｏｆｄｒｏｕｇｈｔａｒｅｍａｎｉｆｅｓｔｅｄｉｎｒｅｇｉｏｎａｌ⁃ｓｃａｌｅｆｏｒｅｓｔｍｏｒｔａｌｉｔｙｅｖｅｎｔｓ，ｗｈｉｃｈｃａｎｋｉｌｌｍｉｌｌｉｏｎｓｏｆｔｒｅｅｓｉｎａｓｈｏｒｔｔｉｍｅ，ｆｕｒｔｈｅｒａｆｆｅｃｔｉｎｇｒｅｇｉｏｎａｌｃｌｉｍａｔｅａｎｄｅｃｏｓｙｓｔｅｍｓｔｒｕｃｔｕｒｅａｎｄｆｕｎｃｔｉｏｎ．Ｇｉｖｅｎｔｈａｔｔｈｅｆｒｅｑｕｅｎｃｙａｎｄｉｎｔｅｎｓｉｔｙｏｆｅｘｔｒｅｍｅｄｒｏｕｇｈｔｅｖｅｎｔｓｉｎｔｈｅｆｕｔｕｒｅｍａｙｉｎｃｒｅａｓｅｗｉｔｈｉｎｃｒｅａｓｉｎｇｔｅｍｐｅｒａｔｕｒｅ，ｉｔｉｓｕｒｇｅｎｔｔｏｃｌａｒｉｆｙｔｈｅｒｅｓｐｏｎｓｅｓｔｒａｔｅｇｉｅｓｏｆｔｒｅｅｓｔｏｄｒｏｕｇｈｔｓｔｒｅｓｓａｎｄｔｈｅｍｅｃｈａｎｉｓｍｓｏｆｔｈｅｉｒｓｕｒｖｉｖａｌａｎｄｄｅａｔｈ，ｒｅｖｅａｌｔｈｅｐｈｙｓｉｏｌｏｇｉｃａｌｍｅｃｈａｎｉｓｍｏｆｗｏｏｄｙｐｌａｎｔｓｉｎａｒｉｄｅｎｖｉｒｏｎｍｅｎｔ，ｕｎｄｅｒｓｔａｎｄｔｈｅａｄａｐｔａｔｉｏｎｍｅｃｈａｎｉｓｍｏｆｔｒｅｅｓｉｎｆｕｔｕｒｅｃｌｉｍａｔｅｓ，ａｎｄｉｍｐｒｏｖｅｔｈｅａｃｃｕｒａｃｙｏｆｐｒｅｄｉｃｔｉｎｇｔｈｅｒｅｓｐｏｎｓｅｏｆｔｒｅｅｓｔｏｄｒｏｕｇｈｔｓｔｒｅｓｓ．Ｐｌａｎｔｆｕｎｃｔｉｏｎａｌｔｒａｉｔｓｒｅｆｅｒｔｏｔｈｅｍｏｒｐｈｏｌｏｇｉｃａｌ，ｐｈｙｓｉｏｌｏｇｉｃａｌ，ｏｒｐｈｅｎｏｌｏｇｉｃａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｐｌａｎｔｓａｔｔｈｅｉｎｄｉｖｉｄｕａｌｌｅｖｅｌ，ｗｈｉｃｈｉｎｄｉｒｅｃｔｌｙａｆｆｅｃｔｔｈｅｐｅｒｆｏｒｍａｎｃｅｏｆｐｌａｎｔｓｂｙｄｉｒｅｃｔｌｙａｆｆｅｃｔｉｎｇｔｈｅｇｒｏｗｔｈ，ｓｕｒｖｉｖａｌｏｒｒｅｐｒｏｄｕｃｔｉｏｎｏｆｐｌａｎｔｓ，ａｎｄａｔｔｈｅｓａｍｅｔｉｍｅｒｅｆｌｅｃｔｔｈｅｌｏｎｇ⁃ｔｅｒｍａｄａｐｔａｔｉｏｎｏｆｐｌａｎｔｓｔｏｔｈｅｇｒｏｗｔｈｅｎｖｉｒｏｎｍｅｎｔ．Ｐｌａｎｔｆｕｎｃｔｉｏｎａｌｔｒａｉｔｓａｎｄｔｈｅｉｒｖａｒｉａｔｉｏｎｒｅｇｕｌａｔｉｏｎｓｃａｎｂｅｕｓｅｄｔｏｅｘｐｌａｉｎｔｈｅａｄａｐｔｉｖｅｍｅｃｈａｎｉｓｍａｎｄｆｕｎｃｔｉｏｎａｌｏｐｔｉｍｉｚａｔｉｏｎｍｅｃｈａｎｉｓｍｏｆｐｌａｎｔｓｔｏｔｈｅｅｎｖｉｒｏｎｍｅｎｔ，ａｎｄｈｅｌｐｔｏｐｒｅｄｉｃｔｔｈｅｒｅｓｐｏｎｓｅｏｆｔｒｅｅｓｔｏｄｒｏｕｇｈｔ．Ｃｏｍｐａｒｅｄｗｉｔｈｃｏｍｍｏｎｌｙｕｓｅｄｐｌａｎｔｆｕｎｃｔｉｏｎａｌｔｒａｉｔｓ，ｈｙｄｒａｕｌｉｃｔｒａｉｔｓｍａｙｂｅｔｔｅｒｄｅｓｃｒｉｂｅｔｈｅｒｅｓｐｏｎｓｅｏｆｔｒｅｅｓｔｏｄｒｏｕｇｈｔｓｔｒｅｓｓ．Ｏｎｔｈｅｂａｓｉｓｏｆｃｏｍｍｏｎｐｌａｎｔｆｕｎｃｔｉｏｎａｌｔｒａｉｔｓ，ｗｅｉｎｃｒｅａｓｅｄｔｈｅｈｙｄｒａｕｌｉｃｔｒａｉｔｓｗｈｉｃｈａｒｅｒｅｌａｔｅｄｔｏｗａｔｅｒｔｒａｎｓｐｏｒｔｃａｐａｃｉｔｙａｎｄｄｒｏｕｇｈｔｔｏｌｅｒａｎｃｅａｎｄｓｙｓｔｅｍａｔｉｃａｌｌｙｓｕｍｍａｒｉｚｅｄ：１）ｔｈｅｐｈｙｓｉｃａｌｍｅｃｈａｎｉｓｍｏｆｌｏｎｇ⁃ｄｉｓｔａｎｃｅｗａｔｅｒｔｒａｎｓｐｏｒｔｉｎｘｙｌｅｍ；２）ｐｈａｓｅｓｏｆｄｒｏｕｇｈｔｓｔｒｅｓｓａｎｄｔｈｅｒｅｓｐｏｎｓｅｏｆｐｌａｎｔｓ；３）ｐｌａｓｔｉｃｉｔｙｉｎｐｌａｎｔｆｕｎｃｔｉｏｎａｌｔｒａｉｔｓａｎｄｗａｔｅｒｒｅｇｕｌａｔｉｏｎｓｔｒａｔｅｇｉｅｓ：Ｉｓｏｈｙｄｒｉｃｒｅｇｕｌａｔｉｏｎｓｔｒａｔｅｇｙａｎｄａｎｉｓｏｈｙｄｒｉｃｒｅｇｕｌａｔｉｏｎｓｔｒａｔｅｇｙ，ｘｙｌｅｍｅｆｆｉｃｉｅｎｃｙ⁃ｓａｆｅｔｙｔｒａｄｅ⁃ｏｆｆｓｔｒａｔｅｇｙ，ｃｏｎｓｅｒｖａｔｉｖｅｗａｔｅｒｕｓｅｓｔｒａｔｅｇｙａｎｄｒｉｓｋ⁃ｔａｋｉｎｇｗａｔｅｒｕｓｅｓｔｒａｔｅｇｙ；ａｎｄ４）ｍｅｃｈａｎｉｓｍｓｏｆｄｒｏｕｇｈｔ⁃ｒｅｌａｔｅｄｍｏｒｔａｌｉｔｙ：ｈｙｄｒａｕｌｉｃｆａｉｌｕｒｅｈｙｐｏｔｈｅｓｉｓ，ｃａｒｂｏｎｓｔａｒｖａｔｉｏｎｈｙｐｏｔｈｅｓｉｓａｎｄｂｉｏｔｉｃａｇｅｎｔｓｈｙｐｏｔｈｅｓｉｓ．Ｆｉｎａｌｌｙ，ｔｈｒｅｅｍａｉｎｐｒｏｂｌｅｍｓｗｅｒｅｐｕｔｆｏｒｗａｒｄｔｏｂｅｓｏｌｖｅｄ：１）ｓｔｒｅｎｇｔｈｅｎｉｎｇｔｈｅｉｎｃｌｕｓｉｏｎｏｆｈｙｄｒａｕｌｉｃｔｒａｉｔｓｔｏｃｌａｒｉｆｙｔｈｅｒｅｓｐｏｎｓｅａｎｄｒｅｇｕｌａｔｉｏｎｍｅｃｈａｎｉｓｍｏｆｐｌａｎｔｓｔｏｄｒｏｕｇｈｔｓｔｒｅｓｓ，ｕｎｄｅｒｓｔａｎｄｉｎｇａｎｄｐｒｅｄｉｃｔｉｎｇｐｌａｎｔｓｕｒｖｉｖａｌ，ｇｒｏｗｔｈ，ｄｉｓｔｒｉｂｕｔｉｏｎａｎｄｄｅａｔｈｉｎｔｈｅｃｏｎｔｅｘｔｏｆｇｌｏｂａｌｃｈａｎｇｅ．２）ｓｔｒｅｎｇｔｈｅｎｉｎｇｔｈｅｃｏｎｓｉｄｅｒａｔｉｏｎｏｆｔｈｅｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｄｉｆｆｅｒｅｎｔｐｌａｎｔｔｉｓｓｕｅｔｒａｉｔｓｆｒｏｍｔｈｅｐｅｒｓｐｅｃｔｉｖｅｏｆｔｈｅｗｈｏｌｅｐｌａｎｔ，ｒｅｖｅａｌｉｎｇｔｈｅｄｉｓｔｒｉｂｕｔｉｏｎｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｐｌａｎｔｓｉｎｔｈｅｅｃｏｓｙｓｔｅｍ，ａｎｄｐｒｅｄｉｃｔｉｎｇｃｏｍｍｕｎｉｔｙｃｏｍｐｏｓｉｔｉｏｎ；３）ｔｈｅｐｒｅｃｉｓｅｐｈｙｓｉｏｌｏｇｉｃａｌｍｅｃｈａｎｉｓｍｂｅｈｉｎｄｔｒｅｅｄｅａｔｈｉｓｓｔｉｌｌｕｎｃｌｅａｒ，ｆｕｔｕｒｅｓｔｕｄｉｅｓｎｅｅｄｔｏｆｕｒｔｈｅｒｅｘｐｌｏｒｅｔｈｅｍｅｃｈａｎｉｓｍｓｏｆｄｒｏｕｇｈｔ⁃ｒｅｌａｔｅｄｍｏｒｔａｌｉｔｙ．ＫｅｙＷｏｒｄｓ：ｗｏｏｄｙｐｌａｎｔｓ；ｄｒｏｕｇｈｔｓｔｒｅｓｓ；ｈｙｄｒａｕｌｉｃｔｒａｉｔｓ；ｗａｔｅｒｒｅｇｕｌａｔｉｏｎｓｔｒａｔｅｇｉｅｓ；ｄｒｏｕｇｈｔ⁃ｒｅｌａｔｅｄｍｏｒｔａｌｉｔｙｍｅｃｈａｎｉｓｍｓ㊀自工业革命以来，不断增强的人类活动导致了全球变暖［１２］㊂联合国政府间气候变化专门委员会（ＩＰＣＣ）评估报告表明，２０１１２０２０年全球地表温度比１８５０１９００年高出１．１ħ，预计在２０２１２０４０年全球升温或将达到１．５ħ㊂随着气温上升，未来干旱肯定会恶化（当自然干旱发生时，它们会来的更快，强度更大）［３］㊂较高的温度通常会导致更大的蒸散，与温度较低时相比，土壤和植物会更快的干燥［４］㊂这种全球变化型干旱已经对生态系统产生了严重影响，比如大量树木死亡［５６］㊂区域尺度上的树木死亡事件改变了地表反照率以及地表⁃大气能量和潜热交换，对区域气候产生反馈［７］；广泛的树木死亡事件有能力在十年以下的时间尺度内从根本上改变区域尺度的景观，对生态系统结构和功能产生重大影响［８］㊂在此背景下，我们必须提高预测树木对干旱反应的准确性，以了解树木在未来气候制度下的适应能力［９］㊂植物功能性状是指植物在个体水平上的形态㊁生理或物候特征，它们通过直接影响植物的生长㊁存活或繁殖，从而间接影响植物的性能［１０１１］，同时反映植物对生长环境的长期适应［１２］㊂植物功能性状有助于预测树木对干旱的响应［１２１３］㊂近３０多年来，科研人员常使用植物功能性状及其变异规律来解释植物对环境的适应机制和功能优化机制㊂然而，随着研究的深入，人们逐步发现自然界生长的植物均是通过多个功能性状共同来完成其适应或功能优化，或者说任何一种功能均是通过多种功能性状来协同实现㊂准确量化这些多性状间的权衡和依赖关系，有助于我们更好地揭示植物的生境适应策略㊂然而，研究发现：１）常用植物功能性状的变异性与降水梯度并不一致，例如平均年降水量（Ｍｅａｎａｎｎｕａｌｐｒｅｃｉｐｉｔａｔｉｏｎ，ＭＡＰ）对全球尺度上自然生物群系比叶面积（Ｓｐｅｃｉｆｉｃｌｅａｆａｒｅａ，ＳＬＡ）变异的解释率不到１％；２）常用植物功能性状与干旱引起的树木死亡率的跨物种模式仅存在微弱的相关性，例如纳入ＳＬＡ和木材密度（Ｗｏｏｄｄｅｎｓｉｔｙ，ＷＤ）时，模型对物种死亡率的解释率从只考虑干旱的３０％增加到３７％［１４］㊂相比之下，水力性状可能更好地描述树木对干旱胁迫的响应㊂近年来发现反映植物水分运输能力或植物耐旱性的水力性状如叶片的最大导水率（Ｋｍａｘ）㊁膨压消失点叶水势（Ψｔｌｐ）㊁水力安全边际（Ｈｙｄｒａｕｌｉｃｓａｆｅｔｙｍａｒｇｉｎ，ＨＳＭ）等与降水梯度高度吻合［１５１７］㊂因此纳入水力性状阐明植物对干旱的响应和调节机制，对于理解和预测全球变化背景下植物生存㊁生长㊁分布以及死亡有着重要意义㊂鉴于未来极端干旱事件的频率和强度可能随温度的升高而增加，迫切需要更好地了解植物对干旱胁迫的应对和调节机制以及不同植物的干旱致死机制，本文重点阐述了：１）植物木质部水分运输的物理机制；２）干旱胁迫下植物的水力响应过程；３）植物水分利用策略的多样性；以及４）植物干旱致死机理㊂９８６２㊀７期㊀㊀㊀程莉㊀等：木本植物应对干旱胁迫的响应机制：基于水力学性状视角㊀１㊀植物体内的水分传输与所有维管植物一样，木本植物通过一个复杂的中空死亡细胞（导管或管胞）管道系统，即木质部，将水分从土壤输送到叶片来防止干燥损伤［９］㊂植物木质部长距离水分运输是保证植物体内水分平衡㊁叶片气孔运动㊁光合作用以及其它各种代谢活动的主要纽带，被称为植物生理学的支柱［１８］㊂综述植物体内木质部长距离水分运输过程，特别是了解防止植物蒸腾速率（Ｅ）超过临界速率（Ｅｃｒｉｔ）的结构和生理机制，有助于理解植物发生水力失败和碳饥饿的风险：１）临界蒸腾速率会导致与水力失败和共质体失败相关的木质部水势阈值（Ψｃｒｉｔ）的发生；２）此外，避免Ｅｃｒｉｔ（关闭气孔）对光合作用的影响以及随后对碳水化合物储备的影响对理解碳饥饿至关重要［１９２０］㊂为了维持组织的水合和光合作用，植物必须补充蒸腾作用损失的水分［８］㊂内聚力⁃张力假说（Ｃ⁃Ｔ理论）认为，蒸腾拉力是水分沿木质部上升的主要驱动力，叶面的蒸腾拉力将土壤中的水分通过植物木质部长距离运输提升到冠层并扩散到大气中［８，２１２２］，这样从根系到叶片的水就能补充蒸腾作用损失的水分［２３］㊂其中，蒸腾拉力（Ｅ）可以通过土壤⁃植物⁃大气水力连续体的稳态公式明确描述［８］：Ｅ＝Ｋ１（Ψｓ－Ψｌｅａｆ－ｈρｗｇ）式中，Ｅ为叶片蒸腾拉力，Ｋ１为叶片水力导度，Ψｓ是土壤水势，Ψｌｅａｆ是叶水势，ｈρｗｇ是高度为ｈ，密度为ρｗ的水柱的重力拉力㊂当Ｅ为０时，Ψｌｅａｆ＝Ψｓ（图１Ａ，ａ点）㊂随着Ｅ的增加，当Ｋ１保持不变时，导管并未发生空穴化，植物体内的张力差（Ψｓ－Ψｌｅａｆ）与Ｅ成正比，Ψｌｅａｆ逐渐下降（图１左，虚线ａｂ）㊂然而气种假说表明：木质部导管中的水柱在张力作用下处于亚稳定状态，导管中的亚稳态液流所承受的张力随Ｅ的增加而增加，此时空气经由木质部导管壁上的纹孔膜进入导管，导管开始发生空穴化，空穴化的发展逐渐加重木质部导管栓塞程度，Ｋ１逐渐下降㊂当Ｅ每增加一个单位时，由于Ｋ１的下降，会导致Ψｌｅａｆ的下降逐渐增大（图１左，实线ａｃ）㊂当Ｅ超过Ｅｃｒｉｔ时，木质部水势（Ψ）超过Ψｃｒｉｔ，则会发生水力失败㊂在干旱胁迫发生时，干旱降低了根区的Ψｓ，植物在Ｅ较低时便会发生水力失败（图１右，将实线ａｃ和实线ｄｅ进行比较）㊂在昼夜尺度上，植物通过关闭气孔保持Ｅ低于Ｅｃｒｉｔ（植物通过降低气孔导度（Ｇｓ）来响应增加的Ｅ［２４］，气孔闭合程度与导致栓塞的Ψｃｒｉｔ有关［２５］）㊂减少Ｇｓ的好处是减少水分损失，但他的代价是减少二氧化碳（ＣＯ２）从大气扩散到羧基化位点，从而限制光合作用对ＣＯ２的吸收［２０］，这种水分流失和ＣＯ２吸收之间的平衡可能会在干旱期间导致植物出现生存㊁水力衰竭和碳饥饿三种结果㊂图１㊀基于达西定律模型求解的蒸腾拉力（Ｅ）与叶水势（Ψｌｅａｆ）的变化Ｆｉｇ．１㊀Ｔｈｅｔｒａｎｓｐｉｒａｔｉｏｎｒａｔｅ（Ｅ）ｖｅｒｓｕｓｌｅａｆｗａｔｅｒｐｏｔｅｎｔｉａｌ（Ψｌｅａｆ）ｉｓｂａｓｅｄｏｎｔｈｅｍｏｄｅｌｓｏｌｕｔｉｏｎｏｆＤａｒｃｙᶄｓｌａｗΨｓ是土壤水势；Ｅｃｒｉｔ是最大蒸腾速率，取决于Ψｓ；Ψｃｒｉｔ是Ｅｃｒｉｔ处的Ψｌｅａｆ，也是允许水分吸收的最低Ψｓ２㊀植物应对干旱胁迫的水力响应过程植物应对干旱胁迫的响应过程主要分为两个阶段：１）干旱胁迫开始到气孔闭合期间；２）气孔闭合到木质０９６２㊀生㊀态㊀学㊀报㊀㊀㊀４４卷㊀部完全栓塞期间［２６］㊂在干旱期间，降水减少导致土壤湿度下降，这往往伴随着更高的温度和增加的大气蒸发需求，这些因素结合在一起引起植物的水分胁迫，导致植物Ψｘ下降（木质部水柱所受张力增加），因此植物关闭气孔以限制水分流失和延缓Ψｘ的下降㊂最近研究表明，尽管气孔关闭会造成一系列负面影响，但气孔仍旧会在木质部水势达到明显的气穴化形成阈值（气孔导度损失８８％对应的水势值，ｔｈｅｗａｔｅｒｐｏｔｅｎｔｉａｌａｔ８８％ｌｏｓｓｏｆｓｔｏｍａｔａｌｃｏｎｄｕｃｔａｎｃｅ，Ｐｇｓ８８）之前关闭［２６２８］㊂气孔关闭后，Ψｘ随着水分通过气孔渗漏［２９］以及表皮和树皮等其他组织损失而继续缓慢下降，植物通过释放内部储存水来缓冲Ψｘ的下降［３０］㊂与此同时，植物整个水力途径的水力导度通过一系列生物物理和生理机制而下降，比如叶脉的可逆塌缩［３１］㊁细胞膜水通道蛋白调节［３２］和细根皮层腔隙的形成［３３］等㊂这一阶段的失水速率通常比气孔完全打开时低１００１０００倍［２９］㊂如果持续干旱，水势持续下降最终达到一个临界阈值（水力导度损失５０％对应的水势值，ｔｈｅｗａｔｅｒｐｏｔｅｎｔｉａｌａｔ５０％ｌｏｓｓｏｆｈｙｄｒａｕｌｉｃｃｏｎｄｕｃｔａｎｃｅ，Ｐ５０）时，栓塞开始在木质部中扩散［３４３５］，这一过程发生在包括植物根茎叶在内的整个水力系统中［３６３７］㊂由于栓塞大大减少了向冠层的水分输送，这种水力功能障碍导致了分支斑块性死亡和冠层叶面积显著减少［３８］㊂随着栓塞逐渐遍布整个输水网络，造成植物水力系统不可逆的损伤（水力导度损失８０％对应的水势值，ｔｈｅｗａｔｅｒｐｏｔｅｎｔｉａｌａｔ８８％ｌｏｓｓｏｆｈｙｄｒａｕｌｉｃｃｏｎｄｕｃｔａｎｃｅ，Ｐ８８），最终导致整株植株死亡㊂图２㊀植物对干旱胁迫的水力响应过程Ｆｉｇ．２㊀Ｐｈａｓｅｏｆｄｒｏｕｇｈｔｒｅｓｐｏｎｓｅｔｏｄｒｏｕｇｈｔｓｔｒｅｓｓｉｎｐｌａｎｔｓ随干旱胁迫增加，虚线代表气孔和表皮导度变化趋势，实线代表木质部水力导度损失率；Ｐｇｓ８８代表气孔关闭时的水势；Ｐ５０和Ｐ８８分别代表水力导度下降５０％和８８％的水势３㊀植物水分运输策略的多样性植物功能性状对植物的建立㊁存活㊁生长和繁殖有很大影响，可以很好地表征植物的生长策略［３９］㊂然而，在哪些性状可以用来评估生态耐旱性方面，我们的知识仍然有限㊂３．１㊀衡量植物抗旱性的性状３．１．１㊀压力⁃容积曲线（Ｐｒｅｓｓｕｒｅ⁃ｖｏｌｕｍｅｃｕｒｖｅ，简称Ｐ⁃Ｖ曲线）基于Ｐ⁃Ｖ曲线计算得到的参数（如膨压消失点叶水势（Ψｔｌｐ）㊁质壁分离时的相对含水量（ＲＷＣｔｌｐ）㊁饱和含水时的叶渗透势（π０）和细胞体积弹性模量（ε））在机制上均与耐旱性有关［４０４１］㊂其中，Ψｔｌｐ代表了引起萎蔫的叶片和土壤的干燥程度［４０］，被认为是最直接量化植物耐旱性的更高级别的性状［４２４３］㊂植物会改变其他Ｐ⁃Ｖ参数：１）渗透调节：积累溶质（减少π０）；２）质外体调节：通过将更多的水重新分配到细胞壁外部来减少共质体水分（增加ａｆ）；３）弹性调节：增加细胞壁的弹性（减少ε）以达到足够负的Ψｔｌｐ值［４１４３］，提高他们的耐１９６２㊀７期㊀㊀㊀程莉㊀等：木本植物应对干旱胁迫的响应机制：基于水力学性状视角㊀２９６２㊀生㊀态㊀学㊀报㊀㊀㊀４４卷㊀旱性㊂然而，由于这些参数通常是同时调整的，因此他们在影响Ψｔｌｐ方面的相对重要性仍然存在争议㊂前人的研究表明，Ψｔｌｐ与干旱指数呈显著正相关，湿润地区的生物群系比干旱区的生物群系具有更小的负值，这支持了膨压消失点叶水势在木本生物群系尺度上反映耐旱性的观点㊂尽管大多数人认为负值较大的Ψｔｌｐ有利于耐旱性，但也有人提出了相反的观点，认为负值较小的Ψｔｌｐ是有益的㊂当Ψｌｅａｆ下降时，负值较小的Ψｔｌｐ使叶片迅速失去膨压并关闭气孔，从而保持较高的ＲＷＣｔｌｐ㊂ＲＷＣｔｌｐ，也被认为是植物耐旱性的重要衡量标准㊂尽管大多数研究认为更负的Ψｔｌｐ有利于耐旱，一些研究则认为维持细胞水合比维持膨压更重要，因为脱水会导致细胞收缩，细胞壁结构损伤以及由于高离子浓度而产生的潜在渗透压，最终破坏代谢过程㊂除此之外，细胞总相对含水量低于７５％时会严重抑制ＡＴＰ，ＲＵＢＰ和蛋白质的产生［４４］㊂Ψｔｌｐ和ＲＷＣｔｌｐ作为耐旱性预测因子的重要性经常受到争议，但没有得到解决㊂一个最近的ｍｅｔａ分析表明Ψｔｌｐ而不是ＲＷＣｔｌｐ驱动物种与栖息地水分供应的关系［４１］㊂３．１．２㊀木质部栓塞脆弱性曲线（Ｖｕｌｎｅｒａｂｉｌｉｔｙｃｕｒｖｅｓ，简称ＶＣｓ）木质部栓塞抗性是决定植物抗旱性的最重要性状之一，也是解释近年来干旱导致植物死亡的重要性状之一［４５］㊂木质部栓塞抗性通常由ＶＣｓ决定，该曲线描述了当Ψｘ降低时，水力导度丧失百分比（Ｐｒｅｃｅｎｔｌｏｓｓｏｆｃｏｎｄｕｃｔｉｖｉｔｙ，ＰＬＣ）如何增加㊂ＶＣｓ可以提供有关特定植物干旱响应的有价值的信息，并已被用于量化植物抗旱性和生态适应性㊂例如，Ｐ５０或Ｐ８８以及水力安全范围被广泛用于量化抗旱性和水力失败的风险［４６］㊂大量研究表明，当Ψｘ降到Ｐ５０或Ｐ８８以下后，Ψｘ很小的变化将引起水分传导速率大幅下降，树木也因此面临严重栓塞及死亡风险㊂Ｐ５０是最常用的栓塞抗性指标㊂Ｌａｍｙ等对地中海松树的５１３种基因型的研究发现，气候差异明显的不同种群其Ｐ５０的遗传和表型变异均有限，Ｐ５０可能是松树固有特征［４５］㊂但是关于栓塞脆弱性的遗传变异和表型可塑性的研究仅限于少数物种，仍需进一步的研究来确定这一结论是否在所有树种中适用㊂物种水平上，对栓塞抗性在木本种中种间变异的ｍｅｔａ分析表明，不同树种木质部栓塞脆弱性存在巨大差异，植物木质部栓塞脆弱性与其生长环境的年平均降水量和干旱程度相关，来自干燥气候的物种比来自湿润气候的物种具有更大的Ｐ５０值，对干旱的忍耐力越强［４７４８］㊂然而在群落水平上，在较干燥的栖息地，植物脆弱性的变化往往很大，这表明脆弱性和干旱在某些情况下是解耦的［４９］㊂这种解耦是因为一些物种所使用的水分胁迫规避策略，如深根系植物或干旱落叶，这些策略使得它们在干旱时期保持较高的Ψｘ［９］㊂具有系统发生学差异的植物，其致死的水势临界点（即木质部导水性不能再恢复）与Ｐ５０或Ｐ８８的关系有所差异㊂裸子植物中的水势临界点与Ｐ５０具有很大正相关性，但被子植物的水势临界点却与Ｐ８８有更高的相关度［９］㊂水力安全范围有２种计算方式：１）ＨＳＭ：树种木质部最低水势（Ψｍｉｎ）与栓塞抗性（Ｐ５０或Ｐ８８）的差值（即Ψｍｉｎ－Ｐ５０或Ψｍｉｎ－Ｐ８８），是预测树木干旱死亡率的关键指标［５０］㊂ＨＳＭ值越小，说明树种面临水力失败的风险越大，反之树种面临水力失败的风险越小［５１］㊂然而，Ｃｈｏａｔ等针对全球８１个地点２２６种森林的研究结果发现，７０％的森林在应对干旱胁迫时的ＨＳＭ很窄（约＜１ＭＰａ），安全边际在很大程度上与年降水量无关，森林对干旱的脆弱性存在全球趋同：所有森林生物群落无论当前的降雨环境如何，都同样容易遭受水力失败［４８］㊂因为Ψｍｉｎ集成了与环境相关的植物结构（例如，生根深度）和生理（例如，气孔行为）性状的许多重要方面，在不同森林类型中发现的狭窄水力安全边际为植物生态学提供了一个重要视角，这表明植物的水力策略是根据其环境进行微调的，允许最大限度的碳获得，但在干旱期间将植物暴露在水力失败的风险中［９］㊂这也表明了一种普遍存在的有风险的策略，即植物对环境的快速变化做出反应的生理潜力有限［９］㊂这加剧了气候变化下极端干旱事件增加所构成的威胁［９］㊂２）气孔安全边际（Ｓｔｏｍａｔａｌｓａｆｅｍａｒｇｉｎ，ＳＳＭ）：气孔闭合时的水势（Ｐｇｓ８８）与抗栓塞能力（Ｐ５０或Ｐ８８）的差值（即Ｐｇｓ８８－Ｐ５０或Ｐｇｓ８８－Ｐ８８），用来反映树种的气孔调控策略［５２］，更直接地将气孔对水势的响应和木质部栓塞抗性结合起来㊂正的ＳＳＭ表明气孔关闭发生在茎严重栓塞之前，而负的ＳＳＭ表明气孔关闭发生在栓塞之后；ＳＳＭ宽的物种的耐旱时间更长㊂有明确证据表明，等水和非等水植物的部分死亡和完全死亡与水力失败有关，这进一步凸显了气孔调节和木质部栓塞抗性之间协调的重要性㊂总的来说，气孔安全边际随着栓塞抗性的增加而持续增加，并且气孔安全边际与水力安全边际相关［５３］㊂最重要的是，将气孔调节策略与木质部水力策略相结合有助于更全面地表达植物对干旱的适应［５４］㊂３．１．３㊀非结构性碳水化合物（ＮＳＣ）ＮＳＣ包括淀粉和可溶性糖［５５５６］，在树木的抗旱性中发挥重要作用［５７］㊂淀粉是一种长期的碳储存分子，它以一种紧凑的㊁不溶性的形式存在，允许植物在高光合速率的情况下储存碳水化合物㊂可溶性糖为植物提供能量和底物，同时也可充当中间代谢产物㊁信号分子或渗透物㊂植物通过光合作用将ＣＯ２固定为碳水化合物，然后用于呼吸㊁防御㊁生长㊁繁殖或在光合作用无法发生时（如夜间㊁休眠季节或环境压力时期）为植物提供能量储备［５８］㊂在干旱胁迫下，ＮＳＣ扮演着两种角色［５９］，缓冲了植物的碳供应不足［６０６１］：１）作为碳饥饿的缓冲㊂在碳饥饿过程中，光合作用受到干旱胁迫，植物缓慢地消耗他们储存的碳水化合物直到死亡［８］㊂因此，生活在炎热和干燥气候中的植物比生活在潮湿气候中的植物分配更多的碳储存，作为应对干旱胁迫的保守缓冲［６２］㊂２）作为渗透缓冲剂㊂当水分胁迫激活淀粉降解酶时，植物可以将不溶性淀粉转化回可溶性糖［６３］㊂这种从淀粉到糖的转化可以降低植物的渗透势，从而在干旱期间维持细胞膨压［６４６５］㊂因此，有人认为在干燥环境中进化或生长的植物将保持较高的ＮＳＣ储存量，并保持更大比例的可溶性糖储存，以防止细胞失水，保持细胞稳定，在干旱条件下生存更长时间［４１，６６６８］㊂３．１．４㊀结构性状结构性状可以很好地反映不同树种面对干旱胁迫时的适应能力㊂比如，叶片厚度（Ｌｅａｆｔｈｉｃｋｎｅｓｓ，ＬＴ）与植物获取㊁利用资源的策略紧密相关㊂具有较高ＬＴ的植物可以增强蓄水能力，避免环境胁迫造成伤害㊂叶干物质含量（Ｌｅａｆｄｒｙｍａｔｔｅｒｃｏｎｔｅｎｔ，ＬＤＭＣ）常用干重和鲜重的比值来表示，干旱地区的植物ＬＤＭＣ也较高，对环境胁迫有较强的抗性［６９］㊂比叶重（Ｌｅａｆｍａｓｓｐｅｒｕｎｉｔａｒｅａ，ＬＭＡ）和叶密度（Ｌｅａｆｄｅｎｓｉｔｙ，ＬＤ）是表示干旱容忍能力的重要叶片功能性状，因为ＬＭＡ较高和ＬＤ较高表明细胞壁较厚或者较密，从而能够较大程度地防止由于叶水势下降引起的变型诱导的损坏㊂ＬＭＡ常用叶片单位面积的干物质量来表示［７０］㊂ＬＭＡ高的植物因其较强的碳同化能力能够更好地生长㊂干旱地区的植物通过提高比叶重来提高植物固持资源（碳㊁氮）的效率，从而提高竞争力㊂ＬＤ反映叶片的紧实程度及植物对外界干旱环境的忍耐能力㊂具有较高ＬＤ的植物通常适应于干旱的生境㊂通常ＬＤ高，则叶片细胞小且细胞壁较厚，能够高效积累渗透物质同时减少水分损失，从而减弱水分可利用性低对叶片造成的破坏㊂胡伯尔值（ＡＬ：ＡＳ）与ＷＤ都是物种对不同水分可利用环境进行水力调节的重要性状㊂ＡＬ：ＡＳ表征枝条对叶片的供水能力，反映蒸腾叶面积与茎输导供水之间的权衡［７１７２］㊂低ＡＬ：ＡＳ可以避免蒸腾过程过度失水，促进叶片水平供水以适应干旱条件，降低水力紊乱的风险㊂ＷＤ常用植物对单位体积木材投资的生物量来表示，反应植物机械支撑㊁水分运输和生长速率［７３］㊂低ＷＤ意味着储水能力较高，有利于木质部再充水而修复栓塞；高ＷＤ意味着较厚的导管壁或较丰富的机械组织，结构紧密，相应的导管面积较小㊂在干旱胁迫的环境中，植物通常具有较高的ＷＤ，保护木质部避免空穴化［７２］㊂根系与土壤环境直接接触，负责吸收养分和水分，但由于其藏匿于地下，根系性状成为了植物对干旱响应的一个重要但被忽视的预测因子［７４］㊂有关根系性状对干旱反应的数据仅限于少数几种植物［７４］㊂因此，关于植物根性状响应策略的结论似乎很特殊，或者年代太久远［７４］㊂例如，有研究报告称，一些植物种因干旱而产生更细的根，具有高比根长（Ｓｐｅｃｉｆｉｃｒｏｏｔｌｅｎｇｔｈ，ＳＲＬ）和比根表面积（Ｓｐｅｃｉｆｉｃｒｏｏｔｓｕｒｆａｃｅａｒｅａ，ＳＲＳＡ），这一策略被解释为以低投资改善水资源获取［７５］㊂相比之下，其他研究报告称，植物种产生的根更粗，ＳＲＬ和ＳＲＳＡ较低，这已被证明可以降低水力失败的风险［７６］㊂更粗的根与通过真菌营养获得高养分和高水分有关［７７７８］，并与由于储存非结构性碳水化合物而产生的渗透调节有关［７９］㊂植物性状有助于预测树木对干旱的响应［７３］㊂相比于常用功能性状，现在已经出现了一套经过充分研究的与耐旱性机制相关的水力性状（表１），被寄予厚望用于预测植物对干旱胁迫的响应，这代表了未来研究的方向［９］㊂３９６２㊀７期㊀㊀㊀程莉㊀等：木本植物应对干旱胁迫的响应机制：基于水力学性状视角㊀表１㊀与树木耐旱性相关的植物水力性状列表Ｔａｂｌｅ１㊀Ｌｉｓｔｏｆｈｙｄｒａｕｌｉｃｔｒａｉｔｓ（ｐｈｙｓｉｏｌｏｇｉｃａｌ，ｍｏｒｐｈｏｌｏｇｉｃａｌ，ａｎｄａｎａｔｏｍｉｃａｌ）ａｓｓｏｃｉａｔｅｄｗｉｔｈｄｒｏｕｇｈｔｔｏｌｅｒａｎｃｅｉｎｔｒｅｅｓ性状Ｔｒａｉｔ性状描述Ｔｒａｉｔｄｅｓｃｒｉｐｔｉｏｎ参考文献Ｒｅｆｅｒｅｎｃｅｓ叶片Ｌｅａｖｅｓ气孔响应Ｓｔｏｍａｔａｌｒｅｓｐｏｎｓｅ气孔闭合速率和敏感性对ＶＰＤ和叶片水势变化［８０８７］膨压消失点和渗透调节Ｔｕｒｇｏｒｌｏｓｓｐｏｉｎｔ＆ｏｓｍｏｔｉｃｒｅｇｕｌａｔｉｏｎ叶片叶肉细胞失去膨压和叶片枯萎的水势，以及叶片叶肉细胞渗透含量的适应性调节［４１，４３，８８９８］最小气孔导度Ｍｉｎｉｍｕｍｓｔｏｍａｔａｌｃｏｎｄｕｃｔａｎｃｅ当气孔处于最小孔径时，叶片角质层的水分损失率［９９１０１］木质部外通路Ｅｘｔｒａｘｙｌａｒｙｐａｔｈｗａｙｓ液体和蒸汽通过叶肉和支持组织的阻力变化［１０２１０４］叶脱落Ｌｅａｆｓｈｅｄｄｉｎｇ在干旱期间通过叶片脱落减少叶面积可以减缓干燥速度，减轻水分对剩余叶片的压力［８７，１０５１０６］气孔解剖结构Ｓｔｏｍａｔａｌａｎａｔｏｍｙ气孔的形状㊁大小和分布，影响失水相关的叶片生理性状［４２，１０７］根系Ｒｏｏｔｓ皮层空腔形成Ｃｏｒｔｉｃａｌｌａｃｕｎａｅｆｏｒｍａｔｉｏｎ根皮层细胞解体，使维管组织从表皮及周围干燥土壤分离［３３，１０８１０９］细根损失Ｆｉｎｅｒｏｏｔｌｏｓｓ细根脱落，减少根系与土壤接触的总表面积，重新平衡根枝比［３３，１０８１１１］根系深度Ｒｏｏｔｉｎｇｄｅｐｔｈ深层根系生长，获得更稳定的水源［１１２１１８］组织性状Ｔｒａｉｔｓａｍｏｎｇｔｉｓｓｕｅｓ栓塞脆弱性Ｖｕｌｎｅｒａｂｉｌｉｔｙｔｏｃａｖｉｔａｔｉｏｎ木质部汁液的负压导致木质部最大水力导度损失５０％或８８％㊂如，裸子植物的生理临界点（Ｐ５０）；被子植物的生理临界点（Ｐ８８）［４７４８，１００，１１９１３８］水容Ｃａｐａｃｉｔａｎｃｅ在木质部周围组织中储存的水分，可以缓冲导致空穴化事件的木质部汁液负液压［３０，１１３，１３９１４１］细胞膜通透性Ｃｅｌｌｍｅｍｂｒａｎｅｐｅｒｍｅａｂｉｌｉｔｙ水通道蛋白的活性可以改变细胞膜的通透性，导致跨膜通路的水力导度降低［３２，１０３，１４２１４３］木质部解剖性状Ｘｙｌｅｍａｎａｔｏｍｉｃａｌｔｒａｉｔｓ木质部导管尺寸㊁数量和连通性Ｘｙｌｅｍｃｏｎｄｕｉｔ木质部导管（管胞和导管）的直径㊁长度和连通性影响最大水力导度和空穴化脆弱性㊂［１３２，１４４１４５］纹孔膜孔隙度／厚度Ｐｉｔｍｅｍｂｒａｎｅｐｏｒｏｓｉｔｙ／ｔｈｉｃｋｎｅｓｓ纹孔膜解剖结构决定了木质部导管之间的空气传播阈值，并影响水力导度和空穴化脆弱性㊂［１２１１２２，１３１，１４６１４７］木材密度Ｗｏｏｄｄｅｎｓｉｔｙ木材密度由木质部解剖性状决定，并与许多生理性状相关㊂［２８，１２７，１４８］连接性Ｓｅｃｔｏｒｉａｌｉｔｙ维管组织的空间分离，防止栓塞在分支间扩散［１４９１５４］㊀㊀ＶＰＤ：饱和水汽压差Ｖａｐｏｒｐｒｅｓｓｕｒｅｄｅｆｉｃｉｔ３．２㊀植物水分利用策略鉴于植物在异质环境中争夺空间㊁阳光㊁水和养分的策略多种多样，任何单一植物功能性状均不足以表征植物在干旱胁迫下的生存力，常需结合一系列形态功能性状㊁生理功能性状㊁生物化学功能性状来阐明植物的水分调节对策及机制，进一步揭示植物对气候变化的响应和适应［１５５］㊂３．２．１㊀等水和非等水调节策略１９３６年，Ｂｅｒｇｅｒ提出等水／非等水概念，基于叶片水势或者蒸腾来描述植物昼夜水分调节关系㊂在昼夜转换间，等水植物会在正午来临时，及时关闭气孔，维持较高的正午叶片水势㊂而非等水植物气孔则持续张开，保持水碳交换，故而正午叶片水势较低㊂近期，研究者将等水／非等水概念用于长期干旱条件下的水分管理［８６］㊂即随着土壤水势的持续降低，等水植物的叶片水势会保持较高水平，然后缓慢降低，而非等水植物的叶片水势会持续降低㊂等水植物的叶片蒸腾随着土壤变干而迅速降低，而非等水植物则先缓慢降低而后加快４９６２㊀生㊀态㊀学㊀报㊀㊀㊀４４卷㊀。

单水氢氧化锂英语

单水氢氧化锂英语English:Lithium hydroxide monohydrate, also known as single lithium hydroxide or single water lithium hydroxide, is a white crystalline powder. It is an inorganic compound with the chemical formula LiOH•H2O. It is commonly used as a component in the production of lithium grease, which is used in lubricating, high temperature applications, and as an electrolyte in the separation of carbon dioxide from natural gas. Additionally, lithium hydroxide monohydrate is utilized in the manufacturing of lithium-ion batteries and as a carbon dioxide scrubber in spacecraft and submarines due to its strong alkaline properties.中文翻译:单水氢氧化锂，又称单水锂氢氧化物，是一种白色结晶粉末。

它是一种无机化合物，化学式为LiOH•H2O。

它通常用作生产润滑脂的成分，在润滑、高温应用中使用，并作为从天然气中分离二氧化碳的电解质。

此外，单水氢氧化锂被用于制造锂离子电池，并作为太空船和潜艇中二氧化碳洗涤器，由于其强碱性能。

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Short communicationWater-stable lithium anode with Li 1.4Al 0.4Ge 1.6(PO 4)3e TiO 2sheet prepared by tape casting method for lithium-air batteriesMing Zhang a ,b ,Keita Takahashi b ,Ichiro Uechi b ,Yasuo Takeda b ,Osamu Yamamoto b ,*,Dongmin Im c ,Dong-Jonne Lee c ,Bo Chi a ,Jian Pu a ,Jian Li a ,Nobuyuki Imanishi baSchool of Materials Science and Engineering,State Key Laboratory of Material Processing and Die &Mould Technology,Huazhong University of Science and Technology,Wuhan,Hubei 430074,PR China bDepartment of Chemistry,Faculty of Engineering,Mie University,Tsu,Mie 514-8507,Japan cSamsung Advanced Institute of Technology,Samsung Electronics,Yongin,Gyeonggi 446-712,Republic of Koreah i g h l i g h t s<Li 1.4Al 0.4Ge 1.6(PO 4)3(LAGP)e 5wt.%TiO 2lithium ion-conducting solid electrolyte sheets were prepared by a tape casting method.<The composite sheet of LAGP and epoxy resin (about 4wt.%)was water impermeable.<The electrical conductivity of the composite sheet was 4.19Â10À4S cm À1at 25 C.<The Li/PEO 18(CF 3SO 2)2N/composite sheet was successfully operated as a lithium electrode in a saturated LiCl aqueous solution.a r t i c l e i n f oArticle history:Received 23December 2012Received in revised form 28January 2013Accepted 30January 2013Available online 13February 2013Keywords:Lithium-air battery Lithium anodeLithium ion conductor NASICON-type 1a b s t r a c tA Li 1.4Al 0.4Ge 1.6(PO 4)3(LAGP)sheet was prepared using a tape casting method with a ﬁne LAGP power prepared from a sol e gel precursor.The addition of nanosize TiO 2as a sintering additive was effective to enhance the ionic conductivity of the tape-cast sheet.The highest electrical conductivity of 8.37Â10À4S cm À1was observed for the tape-cast LAGP sheet with 5wt.%TiO 2at 25 C.A hybrid sheet of the tape-cast LAGP and epoxy resin was water impermeable.The electrical conductivity of the water impermeable hybrid sheet with ca.4%epoxy resin was 4.19Â10À4S cm À1at 25 C.The three-point bending strength of the LAGP e 5wt.%TiO 2e epoxy resin hybrid sheet was 111N mm À2,which is comparable with a Li 1þx þy Al x Ti 2Àx P 3Ày Si y O glass ceramic plate.The Li/PEO 18(CF 3SO 2)2N/LAGP e 5wt.%TiO 2e epoxy sheet was successfully operated as a lithium electrode in saturated LiCl aqueous solution.Ó2013Elsevier B.V.All rights reserved.1.IntroductionLithium-air rechargeable batteries have theoretically higher energy density than lithium ion batteries,and are therefore attracting increased attention as possible power sources for electric vehicles [1e 4].Two types of lithium-air batteries have been developed;aqueous and non-aqueous systems.The non-aqueous system consists of a lithium electrode,a non-aqueous electrolyte,and an air electrode,and are based on two possible reactions [5]:2Li þO 2¼Li 2O 2,(1)and4Li þO 2¼2Li 2O.(2)Reaction (1)is reversible,but reaction (2)is irreversible.In the aqueous system,the lithium electrode is protected by a water-stable lithium ion-conducting solid electrolyte,and the cell reac-tion is [6]:4Li þ6H 2O þO 2¼4(LiOH $H 2O),(3)where water in the electrolyte is involved in the cell reaction.The calculated energy densities including oxygen are 3460Wh kg À1for reaction (1)using an open circuit voltage (OCV)of 2.96V,and 1910Wh kg À1for reaction (3)using an OCV of 3.0V.The non-aqueous system has higher energy density than the aqueous*Corresponding author.Tel.:þ81592319420.E-mail addresses:osyamamo@alles.or.jp ,yamamoto@chem.mie-u.ac.jp(O.Yamamoto).Contents lists available at SciVerse ScienceDirectJournal of Power Sourcesjournal h omepage:www.elsevier.co m/lo cate/jp owsour0378-7753/$e see front matter Ó2013Elsevier B.V.All rights reserved./10.1016/j.jpowsour.2013.01.167Journal of Power Sources 235(2013)117e 121system,but it has some serious problems,including high polari-zation for the charge and discharge processes,electrolyte decom-position,and contamination by moisture in the air.These problems could be overcome for the aqueous system.The most important issue for the aqueous system is to develop a water-stable lithium electrode,because lithium reacts severely with water and should be covered with a water-stable lithium conducting solid electrolyte. Recently,Visco et al.[7]proposed a water-stable lithium metal electrode protected by an NASCION-type water-stable lithium ion-conducting glass ceramic of Li1þxþy Al x Ti2Àx P4Ày Si y O12.(LATP).The discharge product of the aqueous lithium-air system is LiOH,and the LiOH is saturated to approximately5%discharge depth,because of the solubility limit of LiOH in water at room temperature is ca. 5mol LÀTP is unstable in concentrated LiOH aqueous solution, but Imanishi et al.found that LATP is stable in an aqueous solution saturated with LiOH and LiCl[8].Therefore,LATP could be used as the protective layer of a lithium metal electrode for lithium-air batteries with a LiCl saturated aqueous solution.The LATP glass ceramic,which is supplied by Ohara Co.,Japan,had a high lithium ion conductivity of3.5Â10À4S cmÀ1at room temperature.The glass ceramic was prepared by quenching from the melt and crystallized at high temperature.This glass ceramic is expensive and the sizes are limited.We have previously reported that Li1.4Al0.4Ge1.6(PO4)3(LAGP)is stable in an aqueous solution satu-rated with LiOH and LiCl,and the electrical conductivity is higher than that of Li1.4Al0.4Ti1.6(PO4)3[9].LAGP is the other candidate for the protective layer of the water-stable lithium metal electrode.In this study,we have prepared LAGP thin sheet by the tape casting method,which is suitable for the production of large sized thin sheets.The electrical conductivity,mechanical properties,and water permeability of a hybrid sheet prepared with epoxy resin and the tape-cast sheets were examined.In addition,the stability and charge e discharge performance of the Li/PEO18Li(CF3SO2)2N e10% BaTiO3/LAGP e epoxy hybrid sheet/saturated LiCl aqueous solu-tion/Pt cell were GP is unstable in contact with lithium metal;therefore,the polyethylene oxide(PEO)-based polymer electrolyte was used as an interlayer between Li and LAGP.2.ExperimentalThe NASICON-type LAGP powder was prepared using a precursor prepared by the sol e gel method with citric acid,as reported pre-viously[9].Stoichiometric amounts of Ge(OC2H5)4(Aldrich), chemical grade LiNO3,Al(NO3)3$9H2O,and NH4H2PO4were dis-solved in a0.2M aqueous solution of citric acid and stirred contin-uously with a magnetic stirrer to obtain a homogeneous solution.A certain volume of ethylene glycol[citric acid:ethylene glycol molar ratio¼1:1,(citric acidþethylene glycol):(LiþþAl3þþGe4þ)molar ratio¼4:1]was added to the mixed solution to prevent the for-mation of hard agglomerates and promote polyesteriﬁcation and polycondensation.The mixed solution was kept at80 C during the sol e gel preparation process.After a homogeneous solution was formed,the gel was kept at170 C for1day to allow the evaporation of water and to promote esteriﬁcation and polymerization,and the gel was then heated at500 C for4h.The powder obtained was uniformly ground to aﬁne powder with an agate mortar and pestle before sintering at800 C for5h to complete the chemical reaction.Stoichiometric amounts of LAGP powder made by sol e gel method,and TiO2(Aldrich),GeO2(Aldrich),or ZrO2(Tosoh)ﬁne powers were dispersed in ethanol and toluene mixed solution(3:7 volume ratio)using Menhadenﬁsh oil(2wt.%to LAGP)as a dispersant.The mixed slurry was then ball milled with ZrO2balls for24h using high energy mechanical milling(HEMM;Fritsch Planetary Micro Mill).A certain amount of poly(vinyl butyral) (Aldrich,Butvar B-98,7wt.%to LAGP)as a binder and butyl benzyl phthalate(7wt.%to LAGP)as a plasticizer were then added into the mixed slurry and ball milled using HEMM for another24h.The slurry was defoamed for3min using a planetary vacuum mixer (Thinky,Japan)before casting to remove air bubbles.Tape casting was performed on a silicon coated polyethylene substrate foil using double blades with gap heights of700and400m m.The casting speed was constant at60cm minÀ1.After tape casting,the green sheets were left to dry at room temperature for24h.The green sheet was cut into small pieces of1.2e1.5cmÂ1.2e1.5cm.Three green sheets were hot pressed together at90 C for10min and then sintered at900 C in air.The LAGP and epoxy resin hybrid sheets were prepared by dropping a mixed dilute solution of1,3-phenylenediamine (1mol LÀ1)and2,2-bis(4-glycidyloxyphenyl)propane(2mol LÀ1) in tetrahydrofuran on the surface of LAGP sheet.The LAGP sheets with the epoxy resin solution were kept in vacuum for several minutes to allow the solution to penetrate into the pores of the LAGP sheets.The hybrid sheets were then placed into an oven at 80 C for2h and then at150 C for24h to allow evaporation of the solvent and to promote polymerization.The crystal structure of the samples was analyzed using X-ray diffraction(Rigaku RINT-2500)with Cu K a radiation in the2q range from10to90 at a scanning step rate of0.02 sÀ1.Impedance measurements of the LAGP e epoxy resin hybrid sheet with gold electrodes sputtered on both surfaces were conducted using an impedance analyzer(Solartron1260)in the temperature range from20to80 C and in the frequency range of0.01Hz e1MHz.The impedance proﬁles were analyzed using a nonlinear instantﬁt program in the Z-View software.The hybrid sheets were immersed in an aqueous solution with saturated LiOH and LiCl at 60 C for one week to test their stability.The LAGP sheets were then washed with distilled water and dried in a vacuum oven at 110 C for5h before measuring the electrical conductivity and XRD patterns.The epoxy resin content in the samples was estimated from the weight loss measured by thermogravimetric analysis(TGA;Rigaku Thermoplus TG8120).The three-point bending strength of the LAGP sheet was measured using Shimadzu EZ-S500N at room temperature.The water permeation test was performed using an H-type cell with saturated LiCl aqueous solution on one side and distilled water on the other.The LAGP sheet was packed using a plasticﬁlm.The package was then evacuated and heat-sealed apart from a hole with a6mm diameter on the LAGP sheet.The water permeation speed through the LAGP sheet was estimated from the change of the chloride ion content in the distilled water over time,measured using a chorine meter(Kasahara Chemical Instruments).The lithium ion-conducting polymer membrane of PEO18-Li(CF3SO2)2N(LiTFSI)e10%BaTiO3was prepared using a previously reported casting technique[10].A certain amount of PEO(Aldrich, average molecular weight6Â105)powder and lithium salt of LiTFSI (Aldrich)with Li/O¼1/18were dissolved in a certain volume of acetonitrile.10wt.%nanosize BaTiO3particles of(100nm particle size,Sakai Chemical Industry)were added to the solution as the ﬁller.The solution was stirred at room temperature for24h in an Ar-ﬁlled dry glove box.The homogeneous slurry was then cast into a clean Teﬂon dish.The acetonitrile solvent was allowed to evaporate slowly in an Ar-ﬁlled dry glove box for24h,and then dried at110 C for24h under vacuum.The water-stable lithium anode was assembled by laminating lithium metal,PEO18LiTFSI e10wt.% BaTiO3and the LAGP e epoxy resin hybrid sheets in a plastic pack-age,leaving a circular window of6mm in diameter.Nickel foil was used as the anodic current collector.The stability and electro-chemical performance of the water-stable lithium electrode were examined using a beaker-type cell of Li/PEO18LiTFSI e10wt.% BaTiO3/LAGP e epoxy/LiCl saturated aqueous solution/Pt,air at60 C.M.Zhang et al./Journal of Power Sources235(2013)117e121 1183.Results and discussionThe tape-cast ﬁlms sintered at 900 C for 12h showed single phase NASICON-type LAGP without impurity phases such as AlPO 4and GeO 2.However,the mechanical properties of the tape-cast ﬁlm were somewhat poor and the relative density was less than 88%.To improve the mechanical properties,ﬁne powders of TiO 2,ZrO 2,and GeO 2were added into the starting slurry as sintering additives.Fig.1shows XRD patterns of the tape-cast LAGP sheets with 5wt.%TiO 2,3wt.%ZrO 2and 3wt.%GeO 2,along with the lattice GP with 5wt.%TiO 2had no diffraction peaks of TiO 2and the other starting materials.The c -lattice parameter of LAGP (2.0625nm)was decreased (2.0444nm)and the a -lattice param-eter remained unchanged by addition of 5wt.%TiO 2.Some Ti 4þcations may substitute for Ge 4þ.The LAGP sheet with 3wt.%GeO 2shows diffraction peaks of GeO 2,and that with 3wt.%ZrO 2had peaks indicating Li 2Zr(PO 4)3.The c -axis parameter of LAGP with 3wt.%GeO 2was 2.0471nm and the a -axis parameter remained unchanged by the addition of GeO 2.The LAGP with 3wt.%ZrO 2showed no signi ﬁcant change in either of the a -and c -lattice parameters.Fig.2shows typical impedance pro ﬁles for tape-cast LAGP e 5wt.%TiO 2,LAGP e 3wt.%ZrO 2,and LAGP e 3wt.%GeO 2at 25 C,of which the relative densities were 92,91,and 92%,respectively.These relative densities are slightly higher than that of a sintered pellet of LAGP (89.3%)[9].The impedance pro ﬁles are typical of solid ionic conductors with a blocking electrode [11],which con-sists of two semicircles,followed by a straight line.The semicircles are attributed to the bulk and grain boundary resistances;however,the semicircle for the bulk resistance was outside the frequency window examined for the samples.The intercept of the semicircle on the real axis at high frequency represents the bulk resistance (R b ),and the diameter of the semicircle is attributed to the grain boundary resistance (R gb ).The highest conductivity was observed for LAGP e 5wt.%TiO 2,of which the bulk and grain boundary con-ductivities at 25 C were estimated to be 9.54Â10À4and 6.83Â10À3S cm À1,respectively.The total conductivity was 8.37Â10À4S cm À1,which is slightly lower than that of a sintered pellet of LAGP (1.22Â10À3S cm À1)[9].The bulk conductivities of LAGP e 3wt.%GeO 2and LAGP e 3wt.%ZrO 2were lower than that of LAGP e 5wt.%TiO 2.A high grain boundary conductivity of 1.21Â10À2S cm À1for LAGP e 3wt.%GeO 2and a low grain boundaryconductivity of 3.42Â10À3S cm À1for LAGP e 3wt.%ZrO 2were observed.Fig.3shows the electrical conductivity at 25 C of tape-cast sheets of LAGP with TiO 2,ZrO 2,and GeO 2as a function of the additive content.The highest conductivity was observed for LAGP with 5wt.%TiO 2.The relative densities of the LAGP e TiO 2sheets were 88%for LAGP,87%for LAGP e 1wt.%TiO 2,89%for LAGP e 3wt.%TiO 2,92%for LAGP e 5wt.%TiO 2,and 90%for LAGP e 7wt.%TiO 2.The highest conductivity of the LAGP e TiO 2system was observed for the sample with the highest relative density.The mechanical proper-ties were enhanced by the addition of TiO 2into LAGP.The three-point bending strength of LAGP at room temperature was 48N mm À2,which was increased to 74N mm À2by the addition of 5wt.%TiO 2.The highest conductivities were observed at 3wt.%ZrO 2for LAGP e ZrO 2and at 3wt.%GeO 2for LAGP e GeO 2.The acti-vation energies for electrical conduction were estimated from Arrhenius plots to be 30.1kJ mol À1for LAGP e 5wt.%TiO 2,30.2kJ mol À1for LAGP e 3wt.%ZrO 2,and 30.9kJ mol À1for LAGP e 3wt.%GeO 2,which are comparable to that of a sintered LAGP pellet at 31.1kJ mol À1[9].The important requirement for the protective layer of the water-stable lithium electrode is to minimize water permeation through the sheet.Water permeation tests were conducted using the high conductivity LAGP e 5wt.%TiO 2sheet sintered at 900 C for 12h.Fig.4shows the chloride ion transport rate through the ﬁlm at room temperature,where the thickness of the ﬁlm was approxi-mately 0.2mm with a cross-section 0.28cm 2.A linear increase of the chloride ion concentration over time was observed for the tape-cast LAGP e 5wt.%TiO 2sheet;therefore,water easily penetrates through this sheet.The water penetration through the sheet may be due to the presence of open pores in the sheet.A dense sintered body could generally be obtained by sintering at a higher sintering temperature for a long sintering period;however,the tape-cast LAGP sheets sintered at 950 C for 5h and at 900 C for 17h had lower conductivity than that of the tape-cast LAGP sheet sintered at 900 C for 12h,due to the evaporation of lithium oxide at high temperature for long sintering periods.To suppress water perme-ation through the LAGP sheet,the open pores were ﬁlled with epoxy resin,which is stable in water,as reported in our previous paper [12].The water permeation test results through the LAGP e 5wt.%TiO 2e epoxy resin hybrid sheet are shown in Fig.4.TGA suggested that the content of epoxy resin in the hybrid sheet was ca.4wt.%.No chloride ions were detected in the distilled watersideFig.1.XRD patterns and lattices parameters of tape-cast (a)LAGP,(b)LAGP e 5wt.%TiO 2,(c)LAGP e 3wt.%ZrO 2,and (d)LAGP e 3wt.%GeO 2.Fig.2.Impedance pro ﬁles of tape-cast LAGP sheets annealed at 900 C for 12h at 25 C;(-)LAGP e 5wt.%TiO 2,(C )LAGP e 3wt.%ZrO 2,and (:)LAGP e 3wt.%GeO 2.M.Zhang et al./Journal of Power Sources 235(2013)117e 121119of the H-type cell after storage for 7days.The impedance pro ﬁles of the LAGP e 5wt.%TiO 2e epoxy hybrid sheet are compared with that of the LAGP e 5wt.%TiO 2sheet in Fig.5.The bulk conductivity of the hybrid sheet is the same as that of the sheet without epoxy resin,but the grain boundary conductivity of the hybrid sheet is signi ﬁ-cantly decreased from 6.83Â10À3S cm À1for the sheet without epoxy resin to 6.93Â10À4S cm À1.The low grain boundary con-ductivity (high resistance)may be due to the presence of an insu-lator phase of epoxy resin at the grain boundary.The total electrical conductivity of the hybrid sheet (4.19Â10À4S cm À1)at 25 C is approximately half that of the LAGP e 5wt.%TiO 2sheet without epoxy resin,and higher than that of the dense LATP glass ceramic supplied by Ohara Co.,Japan (3.5Â10À4S cm À1)[13]and compa-rable to that of an LATP e epoxy hybrid ﬁlm [12].The mechanical properties of the LAGP e 5wt.%TiO 2were improved by the addition of epoxy resin,The three-point bending strength at room temper-ature of 74N mm À2for LAGP e 5wt.%TiO 2was increased to 111N mm À2by the addition of epoxy resin,which is also compa-rable with that of the Ohara LATP glass ceramic plate and higher than that of the LATP e epoxy hybrid ﬁlm (52N mm À2).The water impermeable LAGP hybrid sheet should be stable in an aqueous solution saturated with LiOH,because the reaction product of aqueous lithium-air batteries is LiOH.We have previ-ously reported that a saturated aqueous solution of LiCl and LiOH has a low pH of ca.9,due to the low dissociation of LiOH in thepresence of a high concentration of Li þ[8].The impedance pro ﬁles of the LAGP e 5wt.%TiO 2e epoxy resin hybrid sheet immersed in saturated LiCl aqueous solution and saturated LiCl and LiOH aqueous solution at 50 C for one week are shown in Fig.5.Both the bulk and grain boundary resistances are comparable before and after immersion in these solutions.XRD analysis also indicated no structural change in the hybrid sheets by immersion in these so-lutions.Therefore,it could be concluded that the LAGP e 5wt.%TiO 2e epoxy resin hybrid sheet is stable in saturated LiCl and LiOH aqueous solution and is thus suitable as the protective layer of a water-stable lithium metal electrode.The stability and electrochemical performance of the water-stable lithium metal electrode with the LAGP e 5wt.%TiO 2e epoxy resin hybrid sheet as the protective layer were examined.Imped-ance pro ﬁles of the Li/PEO 18LiTFSI e 10wt.%BaTiO 3/LAGP e 5wt.%TiO 2e epoxy resin hybrid/saturated LiCl aqueous solution/Pt plate with Pt black,air cell measured at 60 C are shown as a function of the storage time in Fig.6.The polymer electrolyte was used to prevent direct contact between the lithium metal and the LAGP sheet,because LAGP is unstable in contact with lithium metal [9].The room temperature conductivity of the polymer electrolyte was too low to pass a high current;therefore,the stability testwasFig.3.Electrical conductivities of tape-cast (-)LAGP e TiO 2,(C )LAGP e ZrO 2,and (:)LAGP e GeO 2at 25 C as a function of the content of MO 2and the Arrhenius total electrical conductivity plots of tape-cast (-)LAGP e 5wt.%TiO 2,(C )LAGP e 3wt.%ZrO 2and (:)LAGP e 3wt.%GeO 2.Fig.4.The water permeation test results of tape-cast (a)LAGP e 5wt.%TiO 2and (b)LAGP e 5wt.%TiO 2e epoxy resin hybrid sheets at roomtemperature.Fig.5.Impedance pro ﬁles of tape-cast (a)LAGP e 5wt.%TiO 2,(b)LAGP e 5wt.%TiO 2e epoxy,and (c)LAGP e 5wt.%TiO 2e epoxy sheets immersed in saturated LiCl aqueous solution at 50 C for one week,and (d)LAGP e 5wt.%TiO 2e epoxy resin hybrid sheet immersed in saturated LiCl and LiOH aqueous solution at 50 C for one week.M.Zhang et al./Journal of Power Sources 235(2013)117e 121120conducted at 60 C.Two semicircles are evident in the impedance pro ﬁles.The semicircle at the high frequency range corresponds to the contribution of the grain boundary resistance of the LAGP hybrid ﬁlm and polymer electrolyte (R 1),because similar semi-circles were observed in the same frequency range for Au/LAGP e 5wt.%TiO 2e epoxy resin/Au and Au/PEO 18LiTFSI e 10wt.%BaTiO 3/Au.The semicircle in the low frequency range may be attributed to the interface layer between lithium and the polymer electrolyte (R 2)and the charge transfer resistance (R c )between lithium metal and the interface layer [14].No signi ﬁcant change of the impedance pro ﬁles was observed for a storage time of 15days.If water pene-trates through the ﬁlm,it will react with lithium through the PEO layer (PEO is soluble in water),and the cell resistance would be signi ﬁcantly increased.However,the lack of change in the cell resistance con ﬁrms that the hybrid sheet is water impermeable,as observed in the water penetration test.The impedance spectra were analyzed using the equivalent circuit shown as an inset in Fig.6,and the following results were obtained at 60 C:R b ¼50,R 1¼83,R 2¼98,and R c ¼17U cm 2,where R b is the bulk resistance of the hybrid sheet and the polymer electrolyte.The charge transfer resistance is not as high as the other resistances.To reduce the cell resistance,the resistance of LAGP (R b þR 1)and the interface layer between lithium and polymer electrolyte (R 2)should be improved.Recently,Liu et al.reported that the interface resistance between PEO 18LiTFSI and lithium was reduced to ca.25U cm 2by the co-doping of an ionic liquid and nanosize SiO 2into the polymer elec-trolyte [15].The change of the lithium electrode OCV with the storage time is shown as an inset in Fig.6.The stable OCV for the lithium electrode of 3.4V vs.Pt/air was observed for 15days,and is comparable to theoretical OCV.Fig.7shows the change in the potential of the lithium electrode by lithium deposition and stripping for the Li/PEO 18LiTFSI e 10wt.%BaTiO 3/LAGP e 5wt.%TiO 2e epoxy resin/saturated LiCl aqueous so-lution/Pt plate with Pt black,air cell at 60 C,where the lithium electrode potentials were measured using a Pt black reference electrode.The lithium deposition and stripping overpotential of the water-stable electrode was around 0.5V at 0.5mA cm À2.The overpotential caused by cell resistance is 0.125V;therefore,the electrode polarization by the lithium deposition and stripping processes should be reduced to pass a higher current density for application as a power source in electrical vehicles.4.ConclusionsA high conductivity and water impermeable LAGP e 5wt.%TiO 2e epoxy hybrid sheet with a thickness of ca.200m m was prepared by the tape casting method.The electrical conductivity of the hybrid ﬁlm was 4.19Â10À4S cm À1at 25 C,which is comparable to that of a tape-cast LATP e 3wt.%TiO 2e epoxy sheet and is higher than that of an Ohara LATP glass ceramic plate.The three-point bending strength of the LAGP e epoxy hybrid ﬁlm was 111N mm À2,which is comparable to that of the Ohara glass ceramic,and higher than that of LATP e epoxy hybrid sheet at 60e 100N mm À2.A water-stable lithium electrode with LAGP e 5wt.%TiO 2e epoxy resin hybrid protective ﬁlm with high conductivity and excellent mechanical properties was successfully operated in saturated LiCl aqueous solution.Thus,the hybrid sheet is attractive as a protective layer for the water-stable lithium metal electrode of aqueous lithium-air rechargeable batteries.References[1]M.Armand,J.M.Tarascon,Nature 451(2008)652.[2]G.Girishkumar,B.McCloskey,A.C.Luntz,S.Swanson,W.Wilcke,J.Phys.Chem.Lett.1(2010)2193.[3] A.Kraytsberg,Y.Ein-Eli,J.Power Sources 196(2011)886.[4]J.Christensen,P.Albertus,R.S.Sanchez-Carrera,T.Lohmann, B.Kozinsky,R.Liedtke,J.Ahmed,A.Kojic,J.Electrochem.Soc.159(2012)R1.[5]K.M.Abraham,Z.Jiang,J.Electrochem.Soc.143(1996)1.[6]T.Zhang,S.Liu,N.Imanishi,A.Hirano,Y.Takeda,O.Yamamoto,Electro-chemistry 78(2010)360.[7]S.J.Visco,E.Nimon,tz,L.C.D.Jonghe,M.Y.Chu,Abstract ＃53,Interna-tional Meeting on Lithium Batteries,Nara,Japan,2004.[8]Y.Shimonishi,T.Zhang,N.Imanishi,D.Im,D.J.Lee,A.Hirano,Y.Takeda,O.Yamamoto,N.Sammes,J.Power Sources 196(2011)5128.[9]M.Zhang,K.Takahashi,N.Imanishi,Y.Takeda,O.Yamamoto,J.Electrochem.Soc.159(2012)A1114.[10]S.Liu,N.Imanishi,T.Zhang,A.Hirano,Y.Takeda,O.Yamamoto,J.Yang,J.Power Sources 195(2010)6847.[11]P.G.Bruce,A.R.West,J.Electrochem.Soc.130(1983)662.[12]K.Takahashi,P.Johnson,N.Imanishi,N.Sammes,Y.Takeda,O.Yamamoto,J.Electrochem.Soc.159(2012)A1065.[13]K.Takahashi,J.Ohmuram,D.Im,D.J.Lee,T.Zhang,N.Imanishi,A.Hirano,M.B.Phillipps,Y.Takeda,O.Yamamoto,J.Electrochem.Soc.159(2012)A342.[14]T.Zhang,N.Imanishi,S.Hasegawa,A.Hirano,J.Xie,Y.Takeda,O.Yamamoto,N.Sammes,Electrochem.Solid-State Lett.12(2009)A132.[15]S.Liu,H.Wang,N.Imanishi,T.Zhang,A.Hirano,Y.Takeda,O.Yamamoto,J.Yang,J.Power Sources 196(2011)7681.Fig.6.Impedance pro ﬁles of the Li/PEO 18LiTFSI e 10wt.％BaTiO 3/LAGP e 5wt.%TiO 2e epoxy resin hybrid sheet/saturated LiCl aqueous solution/Pt plate with Pt black,air cell at 60 C as a function of storage time and the change of OCV withtime.Fig.7.Change of the lithium electrode potential at 0.5mA cm 2and 60 C in the Li/PEO 18LiTFSI e 10wt.%BaTiO 3/LAGP e 5wt.%TiO 2e epoxy resin/saturated LiCl aqueous solution/Pt plate with Pt black,air cell.M.Zhang et al./Journal of Power Sources 235(2013)117e 121121。

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Water-stable lithium anode with LAGP sheet prepared by tape casting method for lithium-air batteries

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第四部分_锂离子电池

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