batteries_2014_Chemistry

lii阴离子和阳离子半径之比lii阴离子和阳离子半径之比引言：在化学研究中，阴离子和阳离子半径之比（也称为“离子半径比”或“离子半径比值”）是一个重要的概念。

它对于理解和预测化合物的晶体结构、离子间相互作用、化学性质以及溶解度等方面起着重要作用。

其中，lii阴离子和阳离子之间的半径比可能会对化合物的结构和性质产生重要影响。

本文将从简单到复杂，由浅入深地探讨lii阴离子和阳离子半径之比的作用和影响。

一、lii阴离子和阳离子半径之比：概述和基本原理1.1 概述lii阴离子和阳离子半径之比是指lii阴离子半径与阳离子半径之间的比值。

半径比的数值可用于描述离子的大小差异。

如果半径比大于1，表示阳离子的半径较大，反之则表示阴离子的半径较大。

1.2 基本原理离子的大小主要取决于其电荷和电子排布。

由于电子之间的排斥力，带负电的阴离子会比带正电的阳离子半径较大。

当lii阴离子与阳离子结合时，它们的半径比可能会影响离子在晶体结构中的相互排列和排列紧密程度。

这也会影响到化合物的稳定性、离子间相互作用和物理性质等因素。

二、lii阴离子和阳离子半径之比的影响和作用2.1 晶体结构lii阴离子和阳离子半径之比对化合物的晶体结构起着决定性影响。

当半径比较小且接近1时，离子在晶体结构中会比较紧密地排列，形成紧密堆积结构。

在这种情况下，晶体往往具有高密度和较高的熔点。

相反，当半径比较大时，离子之间的相互作用会相对较弱，晶体结构比较松散，从而使得化合物具有较低的密度和较低的熔点。

2.2 化学性质lii阴离子和阳离子半径之比还会对化合物的化学性质产生影响。

当半径比较大时，离子之间的距离较大，电荷分布相对稀疏，导致离子的化学反应性较低。

这意味着化合物在化学反应中可能更加稳定。

相反，当半径比较小时，离子之间的距离较近，电荷分布相对密集，使得离子更容易参与化学反应。

2.3 溶解度lii阴离子和阳离子半径之比还会对化合物的溶解度产生影响。

PROGRESS IN CHEMISTRY化学进展DOI :10.7536/PC130919http :// Progress in Chemistry ,2014,26(4):572~581钠离子电池负极材料∗何菡娜　王海燕∗∗　唐有根　刘又年(中南大学化学化工学院有色金属资源化学教育部重点实验室　长沙410083)摘　要　钠离子电池具有钠资源丰富和成本低廉等特点,吸引了国内外研究者的广泛关注,被认为是今后在规模储能领域可能替代锂离子电池的最佳候选。

近几年钠离子电池的研究相继取得了重要进展,研究体系不断丰富。

本文对钠离子电池负极材料的研究现状进行了详细的综述,重点介绍了碳基材料、合金材料、非金属单质、金属氧化物以及有机化合物等嵌钠性能及可能的嵌钠机理。

探讨了这些材料目前所面临的主要问题及可能的解决策略,并对钠离子电池今后的研究方向和应用前景进行了展望。

关键词　钠离子电池　负极材料　碳基材料　合金　金属氧化物中图分类号:O614.111;TM 912.9　文献标识码:A　文章编号:1005⁃281X(2014)04⁃0572⁃10收稿:2013年9月,收修改稿:2013年11日,网络出版:2014年4月1日　∗国家自然科学基金项目(No.21301193)和中国博士后基金(No.2013M530356)资助The work was supported by the National Natural Science Foundation of China (No.21301193),and the National Science Foundation for Post⁃doctoral Scientists of China (No.2013M530356)∗∗Corresponding author　e⁃mail:wanghy419@Current Studies of Anode Materials for Sodium⁃Ion Battery ∗He Hanna Wang Haiyan ∗∗　Tang Yougen Liu Younian(Key Laboratory of Resources Chemistry of Nonferrous Metals ,Ministry of Education ,School of Chemistry andChemical Engineering ,Central South University ,Changsha 410083,China )Abstract Room⁃temperature rechargeable Na ions batteries have attracted enormous interest due to its low cost and the environmental abundance of the sodium ,which are considered as the best candidate for replacing the Li ion batteries in the large⁃scale electric energy storage.In recent years ,the studies of Na ion batteries have made significant progress and the related components have been enriched.The current researches of anode materials for sodium ion batteries are reviewed in details ,with emphasis on the electrochemical properties and charge⁃discharge mechanisms of carbon⁃based materials ,alloys ,non⁃metal substances ,metal oxides and organic compounds.The main problems of these kinds of anode materials are discussed and the probable strategies are proposed.Then ,the application prospective and the research directions of Na ions batteries in the future are also forecasted.Key words sodium⁃ion battery ;anode material ;carbon⁃based material ;alloys ;metal oxides Contents1　Introduction 2　Carbon⁃based materials 2.1　Graphite2.2　Ungraphitised carbon 3　Metal or alloy materials4　Metal oxides 5　Non⁃metal substance 6　Titanate7　Organic materials 8　Conclusions and outlook何菡娜等:钠离子电池负极材料综述与评论化学进展,2014,26(4):572~581·573　·1　引言能源的储存和转换已成为制约世界经济可持续发展的重要问题。

以葡萄糖为碳源不同碳化方式固体酸催化剂的制备与性能评价张玲玲;刘红茹【摘要】Carbon-based sulfonated solid acid catalysts were prepared using glucose as carbon source and fuming sulfuric acid assulfonation reagentby hydrothermal carbonation and pyrolysis carboniza-tion.Catalysts were characterized by scanning electronmicroscopy(SEM),thermogravimetry(TG),X -ray diffraction(XRD) and Fourier transform infrared(FT-IR) spectroscopy.The catalyst was tested in hydrolysis of cellulose.Results showed that the catalysts prepared by the two carbonization methods were very different in morphology,but they all contained —OH,—COOH,—SO3H functional groups.For hydrolysis of cellulose,under optimized conditions,cellulose hydrolysis rate was up to 60% or more.%以葡萄糖为碳源,发烟硫酸为磺酸化试剂,分别采用水热碳化法和热解碳化法制备碳基固体酸催化剂.使用扫描电镜、热重分析、X射线衍射和傅里叶变换红外光谱等对催化剂进行表征,并评价催化剂在纤维素水解反应中的性能.结果表明,两种碳化方式制备的碳基固体酸催化剂在形貌上具有很大差异,但结构上均含有—OH、—COOH和—SO3H官能团,对于纤维素的水解反应,在150 ℃反应3 h,纤维素水解率超过60%.【期刊名称】《工业催化》【年(卷),期】2018(026)002【总页数】5页(P66-70)【关键词】催化剂工程;固体酸催化剂;水热碳化;水解;热解碳化【作者】张玲玲;刘红茹【作者单位】北京服装学院材料科学与工程学院,服装材料研究开发与评价北京市重点实验室,北京市纺织纳米纤维工程技术研究中心,北京100029;北京服装学院材料科学与工程学院,服装材料研究开发与评价北京市重点实验室,北京市纺织纳米纤维工程技术研究中心,北京100029【正文语种】中文【中图分类】TQ426.6;O643.36酸催化反应是化工领域重要的反应之一，酸催化反应的发展趋势是以环境友好的固体酸代替液体酸。

动力电池的分类一、概述动力电池作为电动汽车的重要组成部分，直接影响着电动汽车的性能和使用体验。

根据电池的不同特点和用途，动力电池可以分为多种不同类型，本文将对这些类型进行详细介绍和比较。

二、锂离子电池2.1 锂铁磷酸电池（LFP）锂铁磷酸电池是一种较为成熟和安全的锂离子电池，具有较高的安全性和长寿命。

它的正极材料是磷酸铁锂，电池具有高温稳定性和较高的充放电效率。

然而，LFP电池的能量密度相对较低，限制了其在纯电动汽车领域的应用。

2.2 锂钴酸电池（LCO）锂钴酸电池具有较高的能量密度和额定电压，使其在电动汽车领域得到广泛应用。

然而，锂钴酸电池存在着较高的成本和较低的循环寿命等问题，同时还具有一定的安全风险，可能存在过热和起火的风险。

2.3 锂镍锰酸电池（NMC）锂镍锰酸电池是目前电动汽车领域应用最广泛的一种动力电池。

它具有较高的能量密度、较长的循环寿命和较低的自放电率。

NMC电池的正极由镍、锰和钴的混合物组成，不同比例的元素可以调节电池的性能。

然而，NMC电池的安全性仍然是一个问题，特别是在放电过程中容易过热。

三、磷酸铁锂电池（LiFePO4）磷酸铁锂电池是一种新兴的动力电池技术，具有良好的安全性、循环寿命和稳定性。

它的正极材料是磷酸铁锂，具有良好的热稳定性和长寿命。

相较于其他类型的锂离子电池，磷酸铁锂电池的能量密度相对较低，体积较大，但在一些特殊的应用场景，如混合动力汽车和储能系统中，仍然有一定的市场需求。

四、聚合物锂离子电池（Li-poly）聚合物锂离子电池是一种较为新颖和前沿的动力电池技术。

它采用了固态聚合物作为电解质，相较于传统液态电解质，聚合物电池具有更高的安全性和稳定性。

此外，聚合物锂离子电池还具有较高的能量密度和灵活的尺寸设计。

然而，目前聚合物电池的循环寿命和成本等问题还需要进一步解决。

五、其他类型电池除了上述主流的动力电池类型，还有一些其他类型的电池也在电动汽车领域有所应用，如燃料电池和钠硫电池等。

Journal of Energy Chemistry23(2014)274–281Hydrothermal synthesis of spindle-like Li2FeSiO4-C compositeas cathode materials for lithium-ion batteriesHaiyan Gao,Zhe Hu,Kai Zhang,Fangyi Cheng,Zhanliang Tao,Jun Chen∗Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),College of Chemistry,CollaborativeInnovation Center of Chemical Science and Engineering,Nankai University,Tianjin300071,China[Manuscript received December2,2013;revised March6,2014]AbstractIn this paper,we report on the preparation of Li2FeSiO4,sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2FeSiO4was synthesized by a facile hydrothermal method with (NH4)2Fe(SO4)2as the iron source.The spindle-like Li2FeSiO4was sintered at600◦C for6h in Ar atmosphere.Li2FeSiO4-C composite was obtained by the hydrothermal treatment of spindle-like Li2FeSiO4in glucose solution at190◦C for3h.Electrochemical measurements show that after carbon coating,the electrode performances such as discharge capacity and high-rate capability are greatly enhanced.In particular, Li2FeSiO4-C with carbon content of7.21wt%delivers the discharge capacities of160.9mAh·g−1at room temperature and213mAh·g−1at 45◦C(0.1C),revealing the potential application in lithium-ion batteries.Key wordsLi2FeSiO4-C composite;spindle like;hydrothermal synthesis;cathode material;lithium-ion battery1.IntroductionPolyanion-type materials such as LiFePO4and Li2MSiO4 (M=Fe,Mn)have attracted a great interest as cathode mate-rials for lithium-ion batteries because of their low cost and high safety[1−4].Among various candidates for the cath-ode,Li2FeSiO4(LFSO)has attracted a great interest owing to its higher theoretical capacity(331mAh·g−1for two Li+ storage per molecule)than that of LiFePO4(170mAh·g−1) [5,6].However,the poor electronic conductivity and ion trans-mittability greatly limit its practical electrochemical perfor-mance[7,8].To solve these problems,recent studies have fo-cused on the strategies of modifying the particle surface with conductive materials(preferably with carbon)[9−11],dop-ing with heteroatoms(Zn2+,Cu2+,Ni2+,or Mn2+)[12−14], and downsizing the particle size into nanoscale[15].In gen-eral,carbon coating is the most widely adopted strategy.This is due to that carbon coating not only increases the apparent conductivity by enhancing the contact between particles but also makes the particles more homogeneous.Therefore,car-bon coating,which is favorable for the transfer of electrons and ions,has an important effect on the structure and electro-chemical performance of LFSO.It is noted that various efforts such as solid-state method, hydrothermal/solvothermal process,and sol-gel route have also been paid to prepare nanostructured Li2FeSiO4-C com-posites[7,14,16].For example,hydrothermal synthesis is an attractive method as it generates crystalline materials with unique morphologies.However,due to the easy oxidation of Fe2+,impurities such as Fe3O4and Li2SiO3often appeared in the final product[17].Thus,pure phase LFSO synthesized by hydrothermal method is still challenging.In this paper,we reported on the synthesis of Li2FeSiO4, sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies as well as their application as the cathode materials of lithium-ion batteries.A hydrothermal method with(NH4)2Fe(SO4)2as the iron source was used to prepare Li2FeSiO4,which is further heated at600◦C for6h in Ar atmosphere.The carbon coating of Li2FeSiO4with glu-cose as carbon resource was adopted to achieve Li2FeSiO4-C composites for improving the electronic conductivity.Elec-trochemical measurements showed that LFSO-C with car-bon content of7.21wt%delivered the discharge capacities of160.9mAh·g−1at room temperature and213mAh·g−1at 45◦C.∗Corresponding author.Tel:+86-22-23506808;Fax:+86-22-23509571;E-mail:chenabc@This work was supported by the Programs of National973(2011CB935900),NSFC(21231005),MOE(B12015and113016A),and the Fundamental Research Funds for the Central Universities.Copyright©2014,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.All rights reserved.doi:10.1016/S2095-4956(14)60147-9Journal of Energy Chemistry V ol.23No.320142752.Experimental2.1.Material synthesis(1)Li2FeSiO4(LFSO)and sintered Li2FeSiO4(S-LFSO)Spindle-like Li2FeSiO4was synthesized by a facile hy-drothermal method with deionized water as solvent.The deionized water was fully boiled before use.The preparation process includes the following steps.First,lithium hydroxide (LiOH·H2O)and silica(SiO2,9nm)were dissolved in40mL deionized water under magnetic stirring at60◦C for about2h. Then,ammonium ferrous sulfate((NH4)2Fe(SO4)2·6H2O), which was dissolved in30mL deionized water,was added slowly.The mixture volume was moderated to80mL by adding deionized water.After stirring for about2min,the mixture was quickly transferred into a100mL Teflon-lined stainless steel autoclave.After sealing,the autoclave was maintained at190◦C for24h.The molar ratio of Li:Fe:Si is 4:1:1with0.1mol·L−1Fe2+concentration.When the reac-tion was completed,the autoclave was cooled to room temper-ature naturally.The precipitates were centrifuged and washed with water and ethanol for several times and finally dried at 40◦C for12h in a vacuum.The pure Li2FeSiO4was recog-nized as LFSO.The pure Li2FeSiO4sintered at600◦C for6h in Ar atmosphere was recognized as S-LFSO.(2)Li2FeSiO4-C(LFSO-C)0.05g pure phase Li2FeSiO4was separately mixed with different contents of glucose(0.05g,0.1g and0.15g)in 16mL boiled deionized water.After ultrasonic treatment for 30min,the mixture was transferred into a20mL Teflon-lined stainless steel autoclave and maintained at190◦C for3h.Af-ter the reaction,the autoclave was cooled to room tempera-ture naturally.After centrifugation,the precipitates were sin-tered at600◦C for6h in Ar atmosphere.The carbon-coated final product was recognized as LFSO-C.The elemental anal-ysis showed that the selected carbon content was3.28wt%, 7.21wt%and11.53wt%,respectively.2.2.Material characterizationThe crystalline structure of the as-synthesized samples was characterized by powder X-ray diffraction(XRD,Rigaku MiniFlex600,Cu Kαradiation).Rietveld refinement was performed using GSAS(General Structure Analysis System) [18,19].The morphology of the samples was observed by scanning electron microscopy(SEM,JEOL,JSM-7500F). The microstructure was measured by transmission electron microcopy(TEM,tecnai G2F20).The weight ratio of the coated carbon of the sample was tested with an elemental analyzer(German,Vario EL CUBE).Raman spectra were recorded using a confocal Raman microscope(DXR,Thermo-Fisher Scientific)with a532nm excitation.2.3.Electrochemical measurementsThe working electrodes were made from a mixture of80wt%of the active material(LFSO,S-LFSO and LFSO-C with the carbon content of3.28wt%,7.21wt% and11.53wt%),10wt%of the polyvinylidene difluoride (PVDF)binder,and10wt%of the conducting agent(Su-per P).The solution of LiPF6(1mol·L−1)dissolved in ethylene carbonate(EC),ethylene methyl carbonate(EMC) and dimethyl carbonate(DMC)(with the volume ratio of EC:EMC:DMC=1:1:1)was used as the electrolyte.The assembled cells were cycled at different charge-discharge rates in the voltage range of1.5–4.8V on a CT2001A cell test instrument(LAND Electronic Co.).Electrochemical impedance spectroscopy(EIS)was performed with AC per-turbation signal of5mV in the range of10−1Hz to105Hz through a Parstat2273A electrochemical workstation(AM-TECT Company).3.Results and discussion3.1.XRD analysisFigure1shows the XRD patterns of the as-prepared LFSO,S-LFSO and LFSO-C.As shown in Figure1(a and b),the observed diffraction peaks of LFSO and S-LFSO can be indexed to the orthorhombic structure(S.G.P mn21)[20], and the monoclinic structure(S.G.P21/n)[21],respectively. This agrees with the previous report that P21/n structure is sta-ble at higher temperature[22].In comparison,LFSO-C has the same structure with S-LFSO.For all samples,no peaks of impure phases such as Fe3O4,Fe2O3,or Li2SiO3are de-tected,indicating the high purity of the products.Insets of Figure1are the crystal structures of each sample,in which all the cations are tetrahedrally coordinated with oxygen atoms. However,along a given crystallographic direction,the con-nectivity is different.In the structure of LFSO,[LiO4],[FeO4] and[SiO4]tetrahedrons share corners with each other.While for S-LFSO and LFSO-C,[FeO4]tetrahedron not only shares a corner with[SiO4]but also shares edge with[LiO4],[FeO4] and[SiO4][22].More details of the rietveld refined XRD patterns of LFSO,S-LFSO and LFSO-C are summarized in Table1.Table1.Structure comparison and electronic conductivityof LFSO,S-LFSO and LFSO-CSpace group P mn21P21P21 a/˚A 6.3042(2)8.2379(1)8.2432(0)b/˚A 5.3696(6) 5.0035(5) 5.0158(6)c/˚A 4.9917(3)8.2392(1)8.2539(7)V/˚A3168.978335.472337.031β/o9098.95(3)99.04(6)wR p14.67%7.16% 6.77%R p10.9% 5.91% 5.16% Carbon content––7.21wt% Electronic conductivity<10−14[16]<10−14[16] 1.07×10−5 (S·cm−1)276Haiyan Gao et al./Journal of Energy Chemistry V ol.23No.32014Figure 1.Rietveld refined XRD patterns of LFSO (a)S-LFSO (b)and LFSO-C (c)with the observed intensity (black plus sign),the calculated intensity (red line),the positions of all possible reflection (green vertical bars)and the difference between the calculated and the observed intensities (blue lines).Insets are the crystal structures of LFSO,S-LFSO and LFSO-C3.2.SEM and TEM analysisFigure 2shows the SEM and TEM images of LFSO,S-LFSO and LFSO-C.As shown in Figure 2(a),the spindle-like LFSO is about 1.6µm in length and 300nm in width.Fig-ure 2(d)further confirms this structure.The high resolution TEM (HRTEM)image in Figure 2(g)taken from the selected area in Figure 2(d)reveals that LFSO is well crystallized with interplanar distance of 0.534nm,corresponding to the (101)plane.The morphology of S-LFSO (Figure 2b and 2e)is sim-ilar with that of LFSO.However,the preferential orientation is different with interplanar distance of 0.264nm,correspond-ing to the (−212)plane (Figure 2h).In comparison,the spin-dle after carbon coating (Figure 2c)is composed of very fine nanoparticles with the size of ∼50nm.TEM image in Fig-ure 2(f)shows that the spindle-like LFSO-C is about 1.7µm in length and 500nm in width.HRTEM in Figure 2(i)displaysthat LFSO-C is well crystallized with interplanar distance of 0.249nm,corresponding to the (202)plane.The carbon layer on the surface of the nanoparticle is about 1nm.The specific surface areas of LFSO,S-LFSO,and LFSO-C with carbon content of 7.21wt%are 25.93,26.72,and 43.5m 2·g −1,re-spectively.3.3.Raman analysisFigure 3(a)shows the Raman spectra of LFSO.Two ob-vious peaks at around 830cm −1and 885cm −1are ascribed to the vibration of Si–O in the structure of [SiO 4].S-LFSO shows the same spectra with that of LFSO but with sharper peaks (Figure 3b).For LFSO-C with different carbon content (Figure 3c–3e),two intense broad peaks at ∼1347cm −1and 1598cm −1can be seen clearly.After fitting the two peaks into four Gaussian bands by a standard peak deconvolutionJournal of Energy Chemistry V ol.23No.32014277procedure,the Raman signals at around 1346cm −1(green line)and 1599cm −1(purple line)are ascribed to D (disor-dered)band and G (graphite)band of sp 2type carbon,re-spectively.While the others at around 1209cm −1(red line)and 1500cm −1(blue line)are related to sp 3type carbon [22].The area ratios of sp 3to sp 2(A sp 3/A sp 2)for LFSO-C containing carbon content of 3.28wt%,7.21wt%,and11.53wt%are 0.57,0.46,and 0.54,respectively.This indi-cates that the coated carbon in LFSO-C mainly exists in sp 2type.Furthermore,the I D /I G ratios for LFSO-C containing carbon content of 3.28wt%,7.21wt%,and 11.53wt%are fitted to 0.753,0.744,and 0.745,respectively.This shows that the graphitization of the coated carbon is high in thecomposite.Figure 2.SEM images (a–c),TEM images (d–f)and HRTEM images (g–i)of LFSO (a,d,g),S-LFSO (b,e,h)and LFSO-C (c,f,i).The insets of (g,h,i)are the corresponding fast Fourier transform (FFT)images of LFSO,S-LFSO and LFSO-C,respectively3.4.Capacity and rate capabilityFigure 4displays the first three charge-discharge curves of LFSO,S-LFSO and LFSO-C (with 7.21wt%carbon)at 0.1C.It can be seen that in the 2nd or 3rd cycle of each sam-ple,the charge plateau is obviously lower than that in the 1st cycle,while the discharge plateau is similar.The lowering of the charge potential plateau is due to the structural rear-rangement,in which some of Li ions (in the 4b site)are inter-changed with Fe ions (in the 2a site)[7].LFSO,S-LFSO and LFSO-C deliver an initial discharge capacity of 15.9,37.2,and 158.9mAh ·g −1,respectively.Higher discharge capacity of LFSO-C than that of LFSO and S-LFSO is due to the rea-sons that:(a)the electronic conductivity has been increased by 9orders of magnitude after carbon coating (Table 1);(b)the nanosize reduces the path for lithium ion diffusion;(c)larger specific area results in more reactive sites.278Haiyan Gao et al./Journal of Energy Chemistry V ol.23No.32014Figure 3.Raman spectra of (a)LFSO,(b)S-LFSO and LFSO-C containing carbon content of (c)3.28wt%,(d)7.21wt%,and (e)11.53wt%.The two broad bands of LFSO-C with different carbon contents are resolved into four linepeaksFigure 4.The first three charge-discharge curves of LFSO,S-LFSO and LFSO-C (with carbon content 7.21wt%)at 0.1C at room temperatureTo investigate the effect of carbon content on the elec-trochemical performance,LFSO-C with selected carbon con-tents (3.28wt%,7.21wt%and 11.53wt%)were tested at different rates (Figure 5a–5c).At 0.1C,0.2C,0.5C,and 1C,LFSO-C with carbon content of 3.28wt%showed the dis-charge capacity of 149.5,131.7,104.6,and 79.3mAh ·g −1,respectively (Figure 5a).While,LFSO-C with carbon content of 7.21wt%showed the discharge capacity of 160.9,144.6,117.1,and 90.4mAh ·g −1at 0.1C,0.2C,0.5C,and 1C,re-spectively (Figure 5b).In comparison,the discharge capacity of 154.6,139.6,111.2,and 86.2mAh ·g −1were obtained for LFSO-C with carbon content of 11.53wt%at 0.1C,0.2C,0.5C,and 1C,respectively (Figure 5c).This means that suit-able content of carbon coating could effectively enhance the electrochemical performance.Figure 5(d)displays the cy-cling performance of LFSO-C with selected carbon contents at different rates.The sample with 7.21wt%carbon showed the highest discharge capacity.Figure 5(e)further illustrates the cycling performance of LFSO-C (7.21wt%C)conducted at 0.2C for 100cycles.After activation for three cycles,the discharge capacity in the forth cycle was 143mAh ·g −1.Af-ter 100cycles,the capacity of 142.4mAh ·g −1was kept with the capacity retention of 99.6%.The coulombic efficiency is higher than 98%.The performance of LFSO-C with 7.21wt%Journal of Energy Chemistry V ol.23No.32014279Figure5.The charge-discharge curves of LFSO-C at different rates with carbon content of3.28wt%(a),7.21wt%(b)and11.53wt%(c);Cycling performance of LFSO-C at different rates with selected carbon contents(d);Cyclic performance and coulombic efficiency of LFSO-C with7.21wt%carbon at0.2C(e)Figure6.The first three charge-discharge curves of LFSO-C with7.21wt%carbon at0.1C(a)and rate cycling performance of LFSO-C with7.21wt%carbon tested at45◦C(b)280Haiyan Gao et al./Journal of Energy Chemistry V ol.23No.32014carbon is comparable to the sample synthesized by hydrother-mal method for 8days [23].Figure 6shows the electrochemical performance of LFSO-C with 7.21wt%carbon tested at 45◦C.As shown in Figure 6(a),the discharge capacity of 213mAh ·g −1was obtained in the 3rd cycle at 0.1C.This equals to about 1.28Li +per molecule.The rate performance in Figure 6(b)shows that after 50cycles,the discharge capacity regains at 200mAh ·g −1.This indicates a high ability of the capac-ity recovery.The electrochemical performance of LFSO-C with 7.21%carbon at 45◦C is much better than the previous report [24].Figure 7shows the SEM image of the electrode of LFSO-C with 7.21wt%carbon after 100cycles.It can be seen that after 100cycling,the spindle morphology of LFSO-C is stillkept.Figure 7.SEM image of LFSO-C with 7.21wt%carbon after 100cyclesFigure 8.Nyquist plots of LFSO-C with carbon contents of 3.28wt%,7.21wt%and 11.53wt%.Cells tested at 30%depth of discharge after 5cycles (0.1C at 2.7V).Inset is the relationship between Z ′and ω−1/2in the low frequency3.5.EIS analysisFigure 8shows the Nyquist plots of LFSO-C with carbon contents of 3.28wt%,7.21wt%and 11.53wt%.When the carbon content is increased,the charge trans-fer resistance (R ct )is getting smaller as can be judged from the radius of the semicircle [25].Smaller R ct value indicates better electronic conductivity.The Li +diffusion coefficients of LFSO-C with carbon content of 3.28wt%,7.21wt%and 11.53wt%are calculated to be 1.01×10−14, 1.68×10−14and 1.54×10−14cm 2·s −1,respectively.4.ConclusionsIn summary,spindle-like Li 2FeSiO 4and Li 2FeSiO 4-C composite with carbon contents of 3.28wt%,7.21wt%and 11.53wt%have been compared as the cathode materials of lithium-ion batteries.With the increasing of the car-bon content,higher electronic conductivity is achieved.By optimization,Li 2FeSiO 4-C composite with 7.21wt%car-bon showed a high discharge capacity of 160.9mAh ·g −1at room temperature and 213mAh ·g −1(equals to about 1.28Li +per molecule)at 45◦C under 0.1C.The result shows that Li 2FeSiO 4-C composite with the adjusting of carbon coating is promising in the application of lithium-ion batteries.AcknowledgementsThis work was supported by the Programs of National 973(2011CB935900),NSFC (21231005),MOE (B12015and 113016A),and the Fundamental Research Funds for the National Key Universi-ties.References[1]Masquelier C,Croguennec L.Chem Rev ,2013,113(8):6552[2]Gong Z L,Yang Y .Energy Environ Sci ,2011,4(9):3223[3]Cheng F Y ,Liang J,Tao Z L,Chen J.Adv Mater ,2011,23(15):1695[4]Chen J,Cheng F Y .Acc Chem Res ,2009,42(6):713[5]Nyt´e n A,Abouimrane A,Armand M,Gustafsson T,Thomas JO.Electrochem Commun ,2005,7(2):156[6]Zhou F,Cococcioni M,Kang K,Ceder G.Electrochem Com-mun ,2004,6(11):1144[7]Nyt´e n A,Kamali S,Haggstrom L,Gustafsson T,Thomas J O.JMater Chem ,2006,16(23):2266[8]Aravindan V ,Karthikeyan K,Kang K S,Yoon W S,Kim W S,Lee Y S.J.Mater Chem ,2011,21(8):2470[9]Li H Q,Zhou H S.Chem Commun ,2012,48(9):1201[10]Zhang K,Hu Z,Chen J.J Energy Chem ,2013,22(2):214[11]Duan W C,Hu Z,Zhang K,Cheng F Y ,Tao Z L,Chen J.Nanoscale ,2013,5(14):6485[12]Deng C,Zhang S,Yang S Y ,Fu B L,Ma L.J Power Sources ,2011,196(1):386[13]Shao B,Abe Y ,Taniguchi I.Powder Technol ,2013,235:1[14]Gao H Y ,Hu Z,Zhang K,Cheng F Y ,Chen J.Chem Commun ,2013,49(29):3040Journal of Energy Chemistry V ol.23No.32014281[15]Zheng Z M,Wang Y,Zhang A,Zhang T R,Cheng F Y,Tao Z L,Chen J.J Power Sources,2012,198:229[16]Dominko R.J Power Sources,2008,184(2):462[17]Yabuuchi N,Yamakawa Y,Yoshii K,Komaba S.Dalton Trans,2011,40(9):1846[18]Toby B H.J Appl Crystallogr,2001,34(2):210[19]Larson A C,V on Dreele R B.General Structure Analysis Sys-tem(GSAS),Los Alamos National Laboratory Report LAUR.1994[20]Sirisopanaporn C,Masquelier C,Bruce P G,Armstrong A R,Dominko R.J Am Chem Soc,2011,133(5):1263[21]Boulineau A,Sirisopanaporn C,Dominko R,Armstrong A R,Bruce P G,Masquelier C.Dalton Trans,2010,39(27):6310 [22]Zhu Z Q,Cheng F Y,Chen J.J Mater Chem A,2013,1(33):9484[23]Yang J L,Kang X C,He D P,Peng T,Hu L,Mu S C.J PowerSources,2013,242:171[24]Yabuuchi N,Yamakawa Y,Yoshii K,Komaba S.Electrochem-istry,2010,78(5):363[25]Gao H Y,Jiao L F,Yang J Q,Qi Z,Wang Y J,Yuan H T.Elec-trochim Acta,2013,97:143。

钴酸锂层状结构钴酸锂是一种重要的无机材料，具有层状结构，其在电池、储能和催化等领域有广泛的应用。

本文将对钴酸锂层状结构进行全面详细、完整且深入的介绍。

1. 钴酸锂的基本概述钴酸锂（LiCoO2）是由锂、钴和氧三种元素组成的无机化合物，具有具有独特的层状结构。

钴酸锂的化学式为LiCoO2，其中钴以高价态+3存在。

它是一种立方晶系的化合物，晶格参数为a=2.838 Å。

钴酸锂在室温下是一种黑色固体，有较高的比表面积和极化率。

2. 钴酸锂层状结构的组成钴酸锂层状结构由钴、锂和氧原子组成。

在结构中，钴原子与六个氧原子配位形成八面体结构，其中四个面被锂原子占据。

每个钴原子由六个氧原子周围的八个八面体共享形成八面体的同心八面体结构。

这种特殊的结构使得钴酸锂层状结构具有很好的离子导电性和电子导电性。

3. 钴酸锂层状结构的性质3.1 离子导电性钴酸锂层状结构中的锂离子在层与层之间的间隙中游离，能够快速地沿着层面移动。

这使得钴酸锂可以作为电池正极材料，用于锂离子电池中。

离子导电性的优秀性质使得钴酸锂能够在电池放电和充电过程中高效地储存和释放锂离子。

3.2 电子导电性钴酸锂层状结构中的钴原子与氧原子形成的八面体框架可以形成电子传导通道。

这种电子导电性使得钴酸锂在催化反应中具有良好的电催化性能。

3.3 结构稳定性钴酸锂层状结构中的离子和电子之间的相互作用使得结构具有较高的稳定性。

这种稳定性使得钴酸锂在高温和高电流密度下都能保持结构的完整性，并具有较长的使用寿命。

4. 钴酸锂层状结构的应用4.1 锂离子电池钴酸锂是最常用的锂离子电池正极材料之一。

其层状结构提供了良好的离子和电子传导通道，使其在锂离子电池中具有较高的电荷和放电性能。

钴酸锂的应用包括移动电子设备、电动汽车、储能系统等。

4.2 催化反应钴酸锂层状结构中的钴具有良好的电催化性能，可用于氧还原反应、水电解和二氧化碳还原等催化反应。

层状结构提供了更多的反应活性位点，使得钴酸锂具有较高的催化活性和稳定性。

硅负极嵌锂过程简介硅负极嵌锂是一种新型的锂离子电池负极材料，具有高容量和高能量密度的特点。

在锂离子电池中，正极材料嵌锂/脱锂的过程是电池充放电循环中的关键环节之一。

而硅负极材料由于其特殊的结构和化学性质，使得其嵌锂过程相对复杂，需要深入研究和优化。

本文将详细介绍硅负极嵌锂过程的原理、影响因素以及相关优化措施。

原理嵌锂机理硅负极材料在充放电循环中发生嵌锂/脱锂反应。

在充电过程中，锂离子从正极经过电解液迁移到负极表面，并与硅形成化合物。

这个过程也被称为嵌入反应。

在放电过程中，这些化合物会释放出嵌入的锂离子，使其返回到正极。

反应方程式硅负极材料与锂离子之间的嵌锂反应可以用以下方程式表示：Si + xLi+ + xe- ↔ LixSi其中，x代表嵌入的锂离子的数量，e-代表电子。

反应机制硅负极材料在充放电循环中经历了多个阶段的反应。

在充电过程中，硅表面形成一层锂化合物膜，阻止进一步的锂离子嵌入。

这个过程被称为SEI（固体电解质界面）膜形成。

当电池开始放电时，SEI膜开始分解，并释放出嵌入的锂离子。

然后，硅会逐渐膨胀，并最终导致材料破裂。

影响因素粒径和结构硅负极材料的粒径和结构对其嵌锂性能有重要影响。

较小的粒径可以增加材料的表面积，并提高锂离子与材料之间的接触面积，从而促进嵌锂反应。

此外，纳米级结构也能够缓解硅在充放电循环中的体积变化问题。

化学组成硅负极材料通常是由纯硅和其他添加剂组成的复合材料。

添加剂的种类和含量可以影响材料的嵌锂性能。

例如，添加一些碳材料可以提高硅负极材料的导电性，促进锂离子的传输。

循环次数硅负极材料在充放电循环中会发生体积变化，这会导致材料疲劳和破裂。

因此，循环次数对硅负极材料的寿命和稳定性有重要影响。

温度温度对硅负极嵌锂过程有显著影响。

较高的温度可以增加反应速率，但也可能导致材料过早失效。

较低的温度则会降低反应速率，但也可能导致电池容量下降。

优化措施纳米结构设计通过控制硅负极材料的纳米结构，可以改善其嵌锂性能。

锂硫电池充电过程的影响因素刘景东【摘要】为了探究多硫离子在多孔碳材料表面的氧化过程,组装了三电极模拟电池和两电极扣式电池.比较了高硫浓度下和低硫浓度下硫电极的循环伏安曲线和充放电曲线;研究了充放电过程中电解液颜色和极片表面颜色的变化;比较了硫浓度、电解液种类、碳材料比表面积对硫电极在2.6 V处氧化峰电流的影响.结果表明:维持硫的适当过饱和度,对硫电极充电过程的完成是必要的;充电过程中可产生单质硫,同时多硫离子还可通过化学过程生成硫.碳比表面积增大,将使氧化峰电流增大;碳酸酯电解液由于对硫和多硫离子溶解度小,氧化峰电流较小;随着硫浓度的增大,氧化峰电流先线性增大,后快速下降.使用醚类电解液时,合适的总硫浓度为0.125 mol/L.【期刊名称】《储能科学与技术》【年(卷),期】2015(004)001【总页数】5页(P61-65)【关键词】多孔材料;循环伏安;电化学行为;锂硫电池【作者】刘景东【作者单位】福州大学化学学院,福建福州350116【正文语种】中文【中图分类】TM912.9锂硫电池理论能量密度虽然高达2600 W·h/kg，但是其容量衰减快，阻碍了其实用化进程[1]。

归纳其容量衰减快的原因有：①飞梭效应，认为由充电产生的高阶多硫离子会迁移至负极与锂反应，发生自放电现象[2]；②硫及多硫离子的溶解，复合于碳基体中的硫溶于电解液导致活性物质损失，从而导致容量衰减[3]；③电极的钝化，深度放电时会生成不溶性的Li2S2和Li2S覆盖在电极表面生成钝化膜[4]。

但哪一种原因为主要，仍没有一种统一的看法。

目前解决容量衰减的方法集中在合成掺杂具有多孔结构的碳材料，或硫化物复合的碳材料上，认为碳材料的微孔具有吸收（吸附）电解液的作用，减小或抑制多硫离子向负极迁移[5-9]；硫电极是液体电极，放电过程是单质硫溶于电解液中，在多孔碳表面逐步得电子，生成高阶多硫离子，高阶多硫离子再得电子同时S—S链断裂生成低阶多硫离子，最后生成Li2S；充电过程是Li2S逐步转化为S8的过程[10]，但上述说法未涉及多硫离子在电解液中的沉淀-溶解反应。

锂硫电池硫／导电聚合物正极材料的研究进展／俞栋等141锂硫电池硫／导电聚合物正极材料的研究进展。

俞栋，徐小虎，李宇洁，汪冬冬，周小中(西北师范大学化学化工学院，生态环境相关高分子材料教育部重点实验室，甘肃省高分子材料重点实验室，兰州730070)摘要综述了锂硫电池硫／导电聚合物正极材料的研究进展。

重点探讨了导电聚合物在硫基正极材料改性中的制备方法、结构设计，并对其中存在的问题进行了分析。

最后对硫／导电聚合物正极材料的进一步发展及商业化应用进行了展望。

关键词锂硫电池正极复合材料导电聚合物中图分类号：TM912文献标识码：A DOI：10．11896／j．iss n 1005—023X 2014．23．029Research Progress of Sulfur／ConductiVe PolymeI’s CathodeMaterials fOr Lithi叫n／SulfurBatteriesYU Dong，XU Xiaohu，LI Yuj ie，WANG Dongdong，ZHOU Xiaozhong (Key Laboratory of Eco_Environment-Related Pol珊er Materials of Ministry of Educa ti on，Ke y L ab or at o ry ofP01)咖er Materials of Gansu P rovin ce，Colle ge of Chemistry&Chemical E n gi n e e ri n g，No rt hw es t N or nl al U ni ve rs it y，L an zh ou 730070)A如sh‘act The res ear ch p r o g r e s s of sulfur／conductive polymers cath ode Imterials for hthiurn／sulfur bat te ri es is s ur n m ar i z ed T h e st r u c t u r al d e s i g n s，p r e p a r a t；o n p r o c e s se s，a n d of c o n d u c t i v e p o l y l n e r s in sulfur composites perfor_m a n c e i m pr o v e m e n t a s cathod e nlateriaIs a r e systeHlaticany discussed and problems as sociated with these rmterials a r ealso analyzed Fina l ly，t he f u rt h er de ve lop me nt an d the commercializat ion of sulfur／conductive polymers cath ode ma te—rials a re d isc uss ed．量(ey w o r d s lithium／sulfur batteries，cathode，composites，conductive polym ers减[20’2¨。