Capacity Fade Mechanisms and Side Reactions in
Lithium-Ion Batteries
锂离子电池容量衰减机机理和副反应
Pankaj Arorat and Ralph E. White*
作者：Pankaj Arorat and Ralph E. White*
Center For Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina,Columbia, South Carolina 29208, USA 美国，南卡罗来纳，年哥伦比亚29208，南卡罗来纳大学，化学工程系，中
心电化学工程
ABSTRACT
The capacity of a lithium-ion battery decreases during cycling. This capacity loss or fade occurs due to several different mechanisms which are due to or are associated with unwanted side reactions that occur in these batteries. These reactions occur during overcharge or overdischarge and cause electrolyte decomposition, passive film formation, active material dissolution, and other phenomena. These capacity loss mechanisms are not included in the present lithium-ion battery mathematical models available in the open literature. Consequently, these models cannot be used to predict cell performance during cycling and under abuse conditions. This article presents a review of the current literature on capacity fade mechanisms and attempts to describe the information needed and the directions that may be taken to include these mechanisms in advanced lithium-ion battery models.
Introduction
摘要
锂离子电池容量随着循环衰减。容量损失或者衰减的发生主要是由于以下几种反应机理，这些机理起因于或者关联于一些我们不希望发生在电池里的副反应。这些反应发生在过充或者过放中，导致了电解液分解、钝化膜的形成、活性物质溶解和其他现象形成。这些容量损失机理并没有包含在目前我们可接触到的公开的锂离子电池数学模型中。因此，这些模型并不能用在预测电池循环或者滥用条件下的电化学行为。这篇文章提出了当前锂离子电池容量衰减机理的观点，并且试图描述我们需要的信息和方向，这些信息和方向有可能被引入先进的锂离子电池模型的机理中。
前言
The typical lithium-ion cell (Fig. 1) is made up of a coke or graphite negative electrode, an electrolyte which serves as an ionic path between electrodes and separates the two materials, and a metal oxide (such as LiCoO2, LiMn2O4, or LiNiO2) positive electrode. This secondary (rechargeable) lithium-ion cell has been commercialized only recently.Batteries based on this concept have reached the consumer market, and lithium-ion electric vehicle batteries are under study in industry.The lithium-ion battery market has been in a period of tremendous growth ever since Sony introduced the first commercial cell in 1990.With energy density exceeding 130 Wh/kg (e.g., Matsushita CGR 17500) and cycle life of more than 1000 cycles (e.g., Sony 18650) in many cases, the lithium-ion battery system has become increasingly popular in applicationssuch as cellular phones, portable computers, and camcorders.As more lithium-ion battery manufacturers enter the market and new materials are developed,cost reduction should spur growth in new applications. Several manufacturers such as Sony Corporation, Sanyo Electric Company, Matsushita Electric Industrial Company, Moli Energy Limited, and A&T Battery Corporation have started manufacturing lithium-ion batteries for cellular phones and laptop computers. Yoda1 has considered this advancement and described a future battery society in which the lithium-ion battery plays a dominant role.
Several mathematical models of these lithium-ion
典型的锂离子电池主要由以下三大部分组成：碳(石墨）负极；电解液，主要提供锂离子传送通道并且分隔开两种材料；过渡金属氧化物正极材料（例如LiCoO2、LiMn2O4或者LiNiO2）。这种二次电池最近已经商业化。这种理念下的电池已经进入消费市场。在工业上，交通工具使用的动力电池已经在研究。自从1990年，索尼首次引进商业化电池，锂离子电池市场在一段时期内取得了巨大增长。在许多条件下，锂离子电池的体积能量密度超过130Wh/kg，循环次数超过1000次，锂离子电池体系在手机、笔记本电脑、便携式摄像机的使用越来越普遍。随着越来越多的电池制造商进入市场，新材料得到发展、成本降低加速了电池的新应用。一部分制造商例如索尼、三洋、松下、Moli能源、A&T电池公司已经开始制作锂离子电池用于移动电话和掌上电脑。Yoda 已经考虑到这些进步并且描述了一个未来的电池社会，在这个社会里锂离子电池扮演非常重要的角色。
已经有一部分锂离子电池的数学模型被出版。不幸的是，
cells have been published. Unfortunately, none of these models include capacity fade processes explicitly in their mathematical description of battery behavior. The objective of the present work is to review the current understanding of the mechanisms of capacity fade in lithium-ion batteries. Advances in modeling lithium-ion cells must result from improvements in the fundamental understanding of these processes and the collection of relevant experimental data.
Some of the processes that are known to lead to capacity fade in lithium-ion cells are lithium deposition (overcharge conditions), electrolyte decomposition, active material dissolution, phase changes in the insertion electrode materials, and passive film formation over the electrode and current collector surfaces. Quantifying these degradation processes will improve the predictive capability of battery models ultimately leading to less expensive and higher quality batteries. Significant improvements are required in performance standards such as energy density and cycle life, while maintaining high environmental, safety, and cost standards. Such progress will require considerable advances in our understanding of electrode and electrolyte materials, and the fundamental physical and chemical processes that lead to capacity loss and resistance increase in commercial lithium-ion batteries. The process of developing mathematical models for lithium ion cells that contain these capacity fade processes not only provides a tool for battery design but also provides a means of understanding better how those processes occur. 他们的模型里所描述锂离子电池的行为中，没有一种模型明确的描述容量衰减过程。他们的主要目的是回顾现有容量衰减机理模型的相关理解认识。要建立新模型，必须建立在对上述这些基础过程的充分理解和收集整合相关数据的的基础上。
大家所知的导致容量衰减的一些过程是锂沉积（过充）、电解液分解、活性物质溶解、插入电极材料的相变，电极和集流体表面钝化膜形成；定量的分析这些退化反应过程将提高电池模型预测能力，最终我们会设计出更便宜质量更好的电池。在电池能量密度、循环性能等方面需要有重大的提升，尽管我们已经达到了环境友好、成本低的标准。取得这些改进，需要我们对电解液、电极材料、以及导致锂离子电池容量衰减和电阻增加的物理化学反应的基本原理的最新的理论知识有足够的了解。锂离子电池容量衰减模型的发展不仅提供了设计电池的工具并且提供了这些过程如何发生的思维方式。
Present Lithium-Ion Battery Models The development of a detailed mathematical model is important to the design and optimization of lithium secondary cells and critical in their scale-up. West developed a pseudo two-dimensional model of a single porous insertion electrode accounting for transport in the solution phase for a binary electrolyte with constant physical properties and diffusion of lithium ions into the cylindrical electrode particles. The insertion process was assumed to be diffusion limited, and hence charge-transfer resistance at the interface between electrolyte and active material was neglected. Later Mao and White developed a similar model with the addition of a separator adjacent to the porous insertion electrode. These models cover only a single porous electrode; thus, they do not have the advantages of a full-cell-sandwich model for the treatment of complex, interacting phenomena between the cell layers. These models confine themselves to treating insertion into TiS2 with the kinetics for the insertion process assumed to be infinitely fast. Spotnitz accounted for electrode kinetics in their model for discharge of the TiS2, intercalation cathode.
The galvanostatic charge and discharge of a lithium metal/solid polymer separator/insertion positive electrode
目前锂电池模型
精细的数学模型的发展对电池后续设计和优化非常重要并且对电池模型规模扩充非常关键。West 提出了类似二维多孔电极模型，该模型解释了具有稳定物理性能的二元电解质的迁移和锂离子扩散到圆柱形的电极；假定嵌入过程的扩散是有限的，因此电解质和活性物质界面的电荷转移阻抗被忽略。随后，Mao和White提出了一个类似的模型，但是增加了一个多孔电极的分割器。这些模型仅仅覆盖了一个单一的电极；因此，它们并没有优势处理复杂“三明治”型的电池模型里正负两个电极之间复杂的相互作用的现象。这个模型限制了它自己本身，因为在分析锂离子嵌入TiS2的过程的动力学，模型假定嵌入行为是非常快。Spotnitz解释了插入型正极TiS2放电过程中电极的电化学动力学。
Doyle根据浓溶液理论建立了金属锂负极/固体聚合物
cell was modeled using concentrated-solution theory by Doyle. The model is general enough to include a wide range of separator materials, lithium salts, and composite insertion electrodes. Concentrated-solution theory is used to describe the transport processes, as it has been concluded that ion pairing and ion association are very important in solid polymer electrolytes. This approach also provides advantages over dilute solution theory to account for volume changes. Butler-V olmer-type kinetic expressions were used in this model to account for the kinetics of the charge-transfer processes at each electrode. The positive electrode insertion process was described using Pick's law with a constant lithium diffusion coefficient in the active material. The volume changes in the system and film formation at the lithium/polymer interface were neglected and a very simplistic case of constant electrode film resistances was considered. Long-term degradation of the cell due to irreversible reactions (side reactions) or loss of interfacial contact is not predictable using this model.
Fuller developed a general model for lithium ion insertion cells that can be applied to any pair of lithium- ion insertion electrodes and any binary electrolyte system given the requisite physical property data. Fuller work demonstrated the importance of knowing the dependence of the open-circuit potential on the state of charge for the insertion materials used in lithium-ion cells. The slopes of these curves control the current distribution inside the porous electrodes, with more sloped open-circuit potential functions leading to more uniform current distributions and 隔膜/嵌入式正极的恒流充放电模型。这是个通用模型，包括（正负极）分离材料、锂盐、复合嵌入式电极。浓溶液理论用来描述传导过程，因为已经得出结论：离子配对和交联在固体聚合物电解质中非常重要。这种方法也为体积变化提供了稀浓度理论；这个模型中使用Butler-V olmer-type 动力学公式解释每个电极电荷转移的过程。正极锂离子嵌入过程采用Pick's 定律描述，锂离子以恒定速率在活性物质中扩散迁移。在锂/聚合物界面的系统和钝化膜的形成过程中，体积变化忽略不计，但是考虑到一个简化了的恒定的电极界面膜阻抗。该模型不能预测电池长久的退化是由于由于不可逆反应（副反应）或接触面损失。
Fuller 提出了一个普遍的锂离子电池模型，该模型可以应用于任何一对锂离子嵌入式电极和二元电解质体系，并给出必要物理性能参数的。Fuller 的模型说明了解锂离子电池嵌入式材料充电状态对开路依赖非常重要。这些曲线的斜率控制了多孔电极材料内部电流分布，开路电压方程曲线的斜率
hence better utilization of active material. Optimization studies were carried out for the Bellcore plastic lithium-ion system. The model was also used to predict the effects of relaxation time on multiple charge-discharge cycles and on peak power.
Doyle modified the dual lithium-ion model to include film resistances on both electrodes and made direct comparisons with experimental cell data for the LiC6-LiPF6, ethylene carbonate/dimethyl carbonate (EC/ DMC), Kynar FLEX-ILiyMn2O4 system. Comparisons between data and the numerical simulations suggested that there is additional resistance present in the system not predicted by present models. The discharge performance of the cells was described satisfactorily by including either a film resistance on the electrode particles or by contact resistances between the cell layers or current-collector interfaces. One emphasis of this work was in the use of the battery model for the design and optimization of the cell for particular applications using simulated Ragone plots.
Thermal modeling is very important for lithium batteries because heat produced during discharge may cause either irreversible side reactions or melting of 越高，电流分布越均一，因此活性物质利用率更高。Bellcore 通信研究所做了一些塑料锂离子电池体系的优化研究。这些模型也用来预测松弛时间对多个充电放电周期和峰值功率的影响。
Doyle改进了双电极模型，包含了双电极的界面阻抗，对比了LiC6-LiPF6（碳酸乙烯酯/碳酸二甲酯（EC / DMC）），聚偏氟乙烯-LiyMn2O4 体系
的实验数据。对比的实验数据和和拟合数据表明体系还有目前电池模型不能预测稍微额外的阻抗存在。电池的放电行为描述比较满意，包括电极材料颗粒表面的膜阻抗，电池电极层之间以及电极和接流体之间的接触阻抗。这项工作的一个重点是为特殊用途的的Ragone 模块电池模型的设计和优化的运用。
电池热建模对锂离子电池非常重要，因为放电过程中产生的热量可能引起不可逆的化
metallic lithium, Chen and Evans carried out a thermal analysts of lithiumion batteries during charge-discharge and thermal runaway using an energy balance and a simplified description of the electrochemical behavior of the system. Their analysis of heat transport and the existence of highly localized heat sources due to battery abuse indicated that localized heating may raise the battery temperature very quickly to the thermal runaway onset temperature, above which it may keep increasing rapidly due to exothermic side reactions triggered at high temperature. Pals and Newman developed a model to predict the thermal behavior of lithium metal-solid polymer electrolyte cells and cell stacks.This model coupled an integrated energy balance to a fullcell- sandwich model of the electrochemical behavior of the cells. Both of these models emphasized the importance of considerations of heat removal and thermal control in lithium polymer battery systems.
Verbrugge and Koch developed a mathematical model for lithium intercalation processes associated with a cylindrical carbon microfiber. They characterized and modeled the lithium intercalation process in single-fiber carbon microelectrodes including transport processes in both phases and the kinetics of charge transfer at the interface. The primary purpose of the model was to predict the potential as a function of fractional occupancy of intercalated lithium. The overcharge protection for a Li/TiS2 cell using redox additives has been theoretically analyzed in terms of a finite linear diffusion model by Narayanan . 学副反应或者熔融的金属锂，陈和Evans利用能量守恒进行了锂离子电池充放电过程的热分析实验以及热散失实验，并且简单描述了体系的电化学行为。他们对热传递以及局部高热量来源的分析，表明局部高热引起电池温度很快升高到热失控温度，由于放热副反应发生，高于这个温度后，电池温度上升更快。Pals 和Newman 提出一个模型预测聚合物电解质电池和电池组的热行为。这个模型联合了一三明治模型电池的热平衡的电化学行为。这两个模型强调了热传递和热控制在聚合物锂离子电池体系中的重要性。
Verbrugge和Koch 提出了一个与圆柱型碳纤维电极的锂离子嵌入过程的数学模型。他们模拟锂离子嵌入单纤维碳电极的过程，包括锂离子在两相的迁移和界面点和传导的动力学。这个模型最初的目的是为了预测电势与嵌入锂的函数关系。Narayanan采用线性扩散模型对Li/TiS的过充保护，电池的氧化还原添加剂进行了理论分析。
Darling and Newman modeled a porous intercalation cathode with two characteristic particle sizes.They reported that electrodes with a particle size distribution show modestly inferior capacity-rate behavior and relaxation on open circuit is substantially faster when the particles are uniformly sized. Nagarajan modeled the effect of particle size distribution on the intercalation electrode behavior during discharge based on packing theory. They observed that during pulse discharge, an electrode consisting of a binary mixture displays higher discharge capacity than an electrode consisting of single sized particles. The current from the smaller particles reverses direction during the rest period which cannot be observed in the case of an electrode comprised of the same-sized particles. Recently Darling and Newman made a first attempt to model side reactions in lithium batteries by incorporating a solvent oxidation side reaction into a lithium-ion battery model, Even though a simplified treatment of the oxidation reaction was used, their model was able to make several interesting conclusions about self-discharge processes in these cells and their impact on positive electrode state-of-charge。
A number of models having varying degrees of sophistication have been developed for lithium rechargeable batteries. For the most part, these models consider the ideal behavior of the systems, neglecting the phenomena that lead to losses in
Darling和Newman建立了具多孔电极以及有两个粒度特征分布的电池模型。他们电极的颗粒粒度只有一个分布的电池显示了较差的倍率性能，有大小分布的开路电压的弛豫时间更快。Nagarajan 以包装理论为基础，建立模型说明了颗粒分布对嵌入电极的放电的影响。他们观察到在脉冲放电的过程，二元混合物电极的放点容量比一个单一粒子组成的电极的容量更高。小颗粒的电流调转方向，但是在单一粒度的电极中并没有观察到。最近，Darling和Newman首次模拟电池的副反应，通过引入一种溶剂的氧化还原副反应到电池模型中。尽管氧化还原简单处理，他们的模型仍然能够得出自放电过程的结论，以及它们对正极充电的影响。
许多复杂程度不同的模型已经被被提出来描述可充电锂离子电池。大多数情况下，这些模型考虑这个体系的理想行为，忽略了在充放电循环过程
capacity and rate capability during repeated charge-discharge cycles. Fundamental models of these latter phenomena are less common because these processes are not as well understood. Also, models of failure modes in batteries do not usually have general applicability to a wide range of systems. However, the importance of these phenomena in the safe and efficient operation of high-energy lithium-ion batteries requires that they be in corporated into future battery models。
Capacily Fading Phenomenon Side reactions and degradation processes in lithium-ion batteries may cause a number of undesirable effects leading to capacity loss. Johnson and White have shown that the capacities of commercial lithium-ion cells fade by ca.10-40% during the first 450 cycles.A flow chart describing many of the processes leading to capacity fade is shown in Fig. 2. In Fig. 3, the capacity fade processes are shown on half-cell discharge curves. This gives a clearer picture of the processes by demonstrating where each is expected to manifest itself during operation of the battery Below, we discuss each of these processes in some detail, after first discussing the general topic of capacity balance.
Capacity Balancing in Lithium-Ion Cells
Lithium-ion cells operate by cycling lithium ions between two insertion electrode hosts having different insertion energies.For optimum 中导致容量和倍率性能损失的现象。这些现象的基础模型比较少见，因为这些过程更加不容易理解。同样，锂离子电池的衰败模型一般不适用于较为广泛的体系。然而，在安全和电池能效方面的现象的重要性需要与未来的电池模型结合。
容量衰减现象
锂离子电池发生的副反应和衰败过程可能引起一系列会导致容量损失的不希望发生的结果。Johnson和White已经证明商业锂离子电池容量在开始的450次循环衰减10-40%，导致容量衰减的一些过程的流程图表如图2所示；图3 中，显示了半电池放电曲线衰减过程。这个图清晰的演示了每个过程，每个预期的电池运行的过程。在讨论了容量平衡的主题之后，我们会讨论了每个过程的细节。
锂离子电池中容量的平衡锂离子电池的运行通过锂离子在两个嵌入式电极之间循环，这两个电极嵌入锂的能量
performance, the ratio of the lithium-ion capacities of the two host materials should be balanced. Capacity balancing refers to the optimization of the mass loading in the two electrodes to achieve the maximum capacity (or energy) from the battery under conditions of steady cycling. Due to the practical importance of this subject for maximizing cell performance, as well as the safety implications with poorly balanced cells, this subject has been discussed in the literature by several authors.
The condition for balanced capacities in a lithium-ion cell can be written in terms of a ratio γof active masses in the electrodes. Written as a ratio of positive to negative electrode masses, this expression is
This equation says that the desired mass ratio depends on the relative coulombic capacities of the two electrodes (C is in units of mAh/g) and the amount of cyclable lithium in each. The cyclable lithium is quantified in terms of the range of lithium stoichiometry in the insertion electrode that can be cycled reversibly, with the notation that Δx refers to the range of negative electrode stoichiometry and Δy to the positive electrode. For some insertion materials, which have several plateaus over which lithium can be inserted and deinserted, one may choose to cycle over only a limited range of stoichiometry for reversibility or safety reasons. In these cases, the stoichiometric range entered in the above formula would be reduced from its maximum 不同。为了优化性能，两种电极的锂离子容量比例应该保持平衡。容量平衡是指在循环稳定的条件下，正负极处的物质量必须获得最高的容量（或者能量）。这个题目的实际意义非常重要，如同不平衡电池的安全性一样重要。并且这些主题已经被很多作者在文献中讨论。
锂离子电池的容量平衡条件可以用方程式表达，与两个电极中的活性物质比例γ 有关。用正极与负极的比例写出，这个表达式是
这个方程式说明理想的比例依两个电极相对的库伦容量和可循环的锂离子的数量而定，可循环的锂离子总数与嵌入电极的可逆的循环锂离子化学计量数有关，Δx符号是指负极化学计量数的变化，Δy是指正极化学计量数的变化。对于一些可嵌入材料，它有几个平台，这些平台超出了锂可逆的平台，考虑到安全和可逆，这样你可以选择在可逆或者安全的化学计量比的平台内。在这种情况下，化学计量数的变化将会减小它的最值。
value.
For example, consider the case of a lithium-ion cell having a petroleum coke negative electrode and a lithium manganese oxide spinel positive electrode. By choice, we can assign useful ranges of stoichiometries for the two electrode materials of 0.61 for the coke and 0.83 for the lithium manganese oxide. These stoichiometric ranges correspond to the following electrochemical processes
The active mass ratio needed to cycle these two materials in the manner shown here is equal to 1.85. This is calculated by using the theoretical capacities of both positive and negative electrode (C÷ = 148 mAh/g and C = 372 mAh/g), equal to F divided by the molecular）.
The situation above d escribes an "ideal" lithium-ion cell in which the capacity balance does not change over the life of the cell. For an ideal cell, the initial lithium capacity available for cycling is constant over the life of the battery .Unfortunately the true case in actual lithium-ion batteriesis more complicated than this, and side reactions and secondary processes are able to perturb the capacity balance from its ideal state. The actual optimized active mass ratiois 2.05-2.15 for the coke/LiMn2O4 system, which corresponds to 14% excess capacity
举个例子，考虑这种情况，锂离子电池是碳负极和尖晶石锰酸锂正极材料，通过选择，我们可以计算两个电极的化学计量比范围，正极尖晶石锰酸锂0.83，碳负极0.61.这些化学计量比对应下面的两个电化学反应过程：
足够循环所需要的活性物质的比是 1.85.这是通过理论计算的两种正负极材料的容量(C = 148 mAh/g and C = 372 mAh/g)，等于法拉第F除以分子量。
以上情况所描述的理想型的锂离子电池，这个理想模型在整个寿命中平衡容量始终没有改变。对这种理想模型，最初循环过程可以利用的锂容量是恒定。不幸的是，真实情况是，实际的电池体系比这个更加复杂，副反应和二级反应过程打乱了理想模型的容量平衡。对于碳负极/LiMn2O4 电池体系，实际最佳化的活性物
in the positive electrode.This excess capacity is a measure of the amount of lithium needed to form a stable film over the electrode surfaces. A major process that affects the capacity balance is the initial formation period needed to passivate carbon-based electrodes. It is now well known that carbonaceous lithium insertion electrodes have irreversible capacity associated with the initial charging cycles. This irreversible capacity loss is thought to result in the formation of a lithium conducting solid electrolyte interface (SEI) layer on the surface of the carbon, while in the process consuming some portion of the cyclable lithium ions in the cell. The loss of cyclable lithium to create this passivation layer has a profound impact on the capacity balance in the cell because it can remove a significant portion of the cyclable lithium depending on the type of carbon used.
If the cyclable lithium in the cell is reduced due to side reactions of any type, the capacity balance is changed irreversibly and the degree of lithium insertion in both electrodes during cell cycling is changed. Consider the case of the initial carbon passivation process that occurs on all lithium-ion cells using carbon-based electrodes. The cell is assembled initially in the discharged state, with the carbon free of lithium and the metal oxide positive electrode at its maximum lithium content. The amount of lithium in either electrode can be represented as shown in Fig. 4, which illustrates the difference between the ideal and actual 质的比是2.05-2.15，也就是正极容量过量了14%，这些过量锂容量的量刚好是形成电极表面的一层稳定的膜的需要量。碳负极首次钝化过程是影响容量平衡的主要过程。周所周知，嵌锂碳负极电极在开始的几次循环会产生一部分不可逆容量。虽然消耗了一些循环锂，但是这些损失的不可逆容量导致了固体电解质钝化膜的形成。损失锂形成的钝化膜对电池的容量平衡有很重要的意义，因为它可以根据使用的负极调节钝化膜用锂量。
电池中任何形式的副反应导致的循环锂的减少，容量平衡都将会发生不可逆的改变，嵌入电极的锂量也会在循环过程中改变。我们需要考虑到碳负极钝化过程发生在所有使用碳负极的锂电池。假定电池开始处于放电状态，碳负极有自由锂，正极过渡金属氧化物在最佳量。任何一个电极的锂量可以用图4表示，这个情况下忽视了碳负极/LiMn2O4电池体系理想电池体系和实际电池
carbon/LiMn2O4 lithium-ion system during the first few cycles.
In an ideal lithium-ion cell (Fig. 4a), all of the lithium should be intercalated into the negative electrode from the positive electrode during the first charge. Similarly all of the lithium ions should be intercalated back into the positive electrode during the first discharge. In an actual lithium- ion cell, upon charging the cell for the first time, some portion of the lithium removed from the LiMn2O4 positive electrode goes into the irreversible film formation reaction while the remainder inserts into the carbon structure. The capacity due to the irreversible reaction is represented schematically in Fig. 4b by the smaller box below the negative electrode. After the cell is finished charging to some arbitrary cut off voltage, the positive electrode has been delithiated to the extent possible under the charging conditions and the negative electrode is as full of lithium as possible given the amount of positive electrode mass available. Ideally the lithium content in the carbon at this point is at its maximum safe value. Also, we can imagine that the passivation layer is fully formed on the initial charging cycle, having consumed a certain amount of cyclable lithium irreversibly.
When this cell is now discharged for the first time, the total quantity of lithium available for discharge is equal only to the amount of lithium reversibly inserted into the carbon electrode. Hence, 体系的最初循环的区别。
在理想的模型中（图4a)，首次充电，所有正极的锂都应该进入负极的夹层中。同样地，在首次放电中，所有负极的锂应该嵌入到正极材料。在实际锂离子电池中，在首次充电的过程中，一部分锂从正极LiMn2O4脱出，参与了不可逆薄膜的形成，剩余的进入了负极碳。不可逆反应的容量如图4b，负极下面的小盒子。当电池充电到一定终止电压，正极脱锂，尽可能使负极充满锂。理想的负极容纳锂量是安全下的。同时，我们可以想象，钝化层在首次充电过程中完全生成，已经消耗了一部分不可逆锂量。
当电池首次放电，可以放出的锂的总数等于嵌入碳负极的可逆锂量。因此，最初损失的不可逆锂无法恢复。放电一
the initial irreversible lithium lost cannot be recovered or utilized. The discharge proceeds until all of the reversible lithium is removed from the carbon electrode. At this time, the stoichiometry in the positive electrode will not reach its initial value upon cell assembly due to the capacity lost on the initial charging cycle. This situation is reflected in Fig. 4 in the bottom diagram. If the cell operates without any additional side reactions for the rest of its life, it will still never utilize the full range of stoichiometry available in the positive electrode. Thus for the above carbon/LiMn2O4 system it is safe to cycle within the limits of Δx = 0.61 (x varying from 0 to 0.61) and Ay = 0.83 (y varying from 0.17 to 1.0) as shown in Fig. 4. It should be remembered that these Ax and Ay values are cell and material specific.
The range of stoichiometries accessed in the negative electrode in this example depends on the positive to negative mass ratio parameter γ. If the ideal value of γhad been used to fabricate this example cell, the initial loss of lithium due to the irreversible passivation process would prevent the carbon electrode from being fully utilized to an extent that depended directly on the amount of irreversible capacity that the particular carbon electrode material exhibited. Rather than let this happen, the common procedure is to assemble cells having a greater than theoretical amount of positive-electrode mass, thus allowing for losses of cyclable lithium during operation by initially providing extra lithium. One method of providing the extra lithium without increasing the cathode 直持续到可逆锂量全部从负极脱出。这时候，脱出锂的化学计量数没有达到最初的数，因为首次充电出现容量损失。这种情况如图4反应。如果电池循环过程中没有副反应，它仍然不会全部利用正极嵌入的锂量。因此，在Δx = 0.61 (x 0 -
0.61) 和Δy = 0.83 (y 0.17 -
1.0) 条件下，碳负极/LiMn2O4电池体系是安全的。我们应该明确，Δx 和Δy值是由电池和材料决定的。
在这个例子中，负极的嵌入的锂的化学计量数的变化依据正极的活性物质与负极活性物质比的参数γ。理想的γ用于实例中的电池，最初因为不可逆钝化膜造成的锂损失会阻碍碳负极全部利用正极的锂，为了不让这发生，一般的过程是组装电池的正极材料超过理论容量，这样，最初过量的锂允许循环锂的损失。Tarascon 和Peramunage提出一种提供过量锂的方法是采用富锂的正极材料（富锂的尖晶石金属氧化物(Li+Mn2O4) ）。
mass is to use overlithiated manganese oxide (Li+Mn2O4) spinel electrodes as proposed by Tarascon and Peramunage.
Even with side reactions and irreversible capacity losses, the desired mass ratio can still be calculated via a formula analogous to the above one, although we must now include in the negative electrode capacity an additive contribution due to the passivation process. Referring to this contribution as C1.. (mAh/g), the capacity balancing condition can be expressed as
For example, in the case of a lithium-ion cell fabricated using a carbon (petroleum coke) negative electrode and a lithium manganese oxide spinel positive electrode, the actual mass ratio desired for optimum utilization of the two electrodes is about 14% larger than its theoretical value. This excess capacity is a measure of the amount of lithium needed to form a stable film over the electrode surfaces. The active mass ratio for the graphite/LiMn2O4 system is ca. 2.4-2.45. Smaller mass ratios will prevent full utilization of the negative electrode whereas larger mass ratios present a safety hazard because the negative electrode can be overcharged (more lithium is available to insert into the electrode than is desirable). Overall cell performance such as energy density is maximized at the optimum mass ratio only.
尽管有副反应和不可逆的容量，设计的物质的量比例仍然能够通过类似于上面的公式计算出来，但是由于钝化反应，我们要把负极添加剂的贡献考虑在内。关于这一容量计做C1，容量平衡可表示为：
举个例子，在使用碳负极和锂锰氧化物尖晶石正极的锂离子电池情况下，实际所需要的正极的量比理论大14%多。这些过量的容量主要用来形成电极表面的钝化膜。活性物质碳负极的比例是 2.4-2.45。较小物质量比会阻止负极的利用率，然而较大的质量比会阻止安全隐患，因为负极可以过充（过多的锂可以插入负极）。总之，电池性能包括能量密度只有在最佳的物质量比下才最大化。
It should also be apparent that there is a relationship between the expected overcharge and overdischarge processes and the cell's capacity balance. For example, in the case of the lithium manganese oxide spinel material discussed above, overcharge reactions involving solvent oxidation depend on the capability of the cell to fully oxidize the positive electrode during normal cycling conditions. For cells with high mass ratios, this may not be possible because the negative electrode becomes fully charged before allowing the positive to become fully charged (i.e., before complete removal of lithium from the positive). Overdischarge of high-mass-ratio cells will affect the negative electrode by emptying the carbon of lithium completely and then driving the negative electrode potential up to an undesirably high value. In other cases, the mass ratio may be lower than desired leading to overcharge of the positive electrode. For example, in the case of the coke/LiMn2O4 system, mass ratios higher than 2.1 can lead to overlithiation of the negative electrode during charge. Mass ratios lower than 2.1 will have less lithium available than needed and will thus result in overdischarge of the negative electrode with accompanying negative safety or performance consequences.
The carbon passivation process is the most common and well-studied example of a side reaction in the lithium-ion cell that will change the
显而易见，电池预料之内的过充过放和电池的容量平衡之间有关系。例如，以上讨论的尖晶石锂锰氧化物，在循环过程中，过充反应里的溶剂氧化，取决于电池本身的情况。有较高物质比的电池，这可能不会发生，因为在负极完全被充满电之前，正极也是完全充满电的。高质量比的电池过放使负极的锂完全被充出，负极电位更负，到不理想的负极电位。其他情况下，质量比可能低于设计，导致正极过充。例如，在碳/LiMn2O4 体系，质量比高于2.1将会导致充电过程中负极有过量的锂。质量比低于2.1将会导致锂不够，这会引起负极的过放，伴随负极安全和影响电池的性能。
碳负极的钝化过程是最常见和研究最广泛的影响电池容量平衡的锂离子电池副反应。
capacity balance.However, a number of other processes are also capable of having this effect. Any side reaction that either produces or consumes lithium ions or electrons will lead to a change in the cell's capacity balance, with the potential to impact negatively the cell's performance. In addition, once the capacity balance is changed from its desired state, the changes are generally irreversible and may accumulate over many cycles to generate a hazardous condition in the cell. Although difficult to quantify experimentally, it is straightforward to follow these effects using battery models and computer simulations under dynamic conditions if the relevant phenomena are included in the models.
Formation Cycles
Lithium-ion cells exhibit a sharp decay in capacity during the first few cycles. This period is known as the formation period during which cells are conditioned prior to use. It is generally desirable for the capacity decay observed after the formation period to be very small compared to the total cell capacity, after which the charge-discharge reactions are nearly 100% efficient. The sharp decay in capacity is due primarily to the solid electrolyte interface layer formation on the negative electrode. Passivation of the carbon electrode during the formation period and subsequent capacity loss are highly dependent on specific properties of the carbon in use, such as degree of crystallinity, surface area, pretreatments, 然而，也有几个其他过程同样具有汇总效果。任何副反应，产生或者消耗锂离子或者电子，都会导致电池容量平衡的改变。另外，一旦容量平衡从理想状态改变，这些改变一般都是不可逆的，可能在循环过程积累，会在电池中产生危害。尽管这些无法用实验量化，如果相关的现象出现在这些模型中，是可以通过实验模型和计算机模拟动态条件，从而直截了当的跟踪这些影响。
化成循环
锂离子电池在最初几次循环过程中出现容量急剧衰减。这个过程就是众所周知的锂离子电池前期必须先发生的化成过程。通常，化成以后的容量循环一般是比较满意，因为相比较整个电池的容量，衰减容量比较小，基本上放电效率是100%。容量急剧衰减主要是由于负极表面固体钝化膜的引起。碳负极在化成的过程形成钝化膜，随后的容量损失主要是跟碳负极的特定性质有关，包括结晶度、比表面积、预处理以及其他合成工艺细节。最
and other synthesis and process details.After the first few cycles, the cell stabilizes and exhibits a constant capacity. The formation cycles are one of the critical steps in the manufacture of lithium-ion systems. For graphitic materials such as Osaka Gas mesocarbon micobeads (MCMB), the irreversible capacity is as low as 8 to 15%, whereas for hard carbons it can be as high as 50% of the reversible capacity.
Fong demonstrated that irreversible reactions occur on carbon-based electrodes during the first discharge in carbonate-based electrolytes prior to the reversible insertion- deinsertion of lithium ions. These irreversible reactions are associated with electrolyte decomposition and cause the formation of a passivating film or solid electrolyte interface on the surface of the carbon. When all the available surface area is coated with a film of decomposition products, further reaction stops. In subsequent cycles, these cells exhibit excellent reversibility and can be cycled without capacity loss for many cycles. These authors first showed that the reversible insertion of lithium into graphitic carbons was possible as long as the proper passivating solvent was present. Gas evolution was observed by Gozdz et al.53 during the formation of the passivation layer on the carbon electrode during the first charge of a lithium-ion cell. The gas evolved correlated well with the irreversible capacity loss observed during the formation cycle. More details of carbon passivation in various solvent systems and the mechanisms of 初几次循环之后，电池开始稳定并且展现出稳定的容量。化成循环过程是锂离子电池体系形成非常关键的过程，石墨材料，例如MCMB，不可逆容量是8-15%，然而，碳黑高达50%的不可逆容量。
芳等人证实了不可逆反应发生在碳负极处，主要是在首次放电时碳酸基电解液里发生，然后是可逆锂的嵌入和脱出。这些不可逆反应与电解液分解以及负极表面形成钝化膜或者固体电解质界面有很大关系。当所有的可接触的面积都有分解产物覆盖时，进一步的反应将会停止。在接下来的循环中，这些电池表现出了较好的可逆性并且循环稳定几乎没有容量衰减。这些学者们首次展示了可逆锂离子插入负极是有可能的，只要是负极表面有钝化剂。Gozdz发现在电池首次充电负极钝化膜形成过程中有气体释放出，气体释放与首次化成不可逆容量的损失有关系。更多关于在不同溶剂中负极钝化膜形成以及钝化过程的机理将会在后续电解液还原以及钝化膜形成的部分重新提
the passivation process are reviewed in later sections on electrolyte reduction and film formation.
The formation period is critical in lithium-ion battery manufacture because of its economic impact. First, it obligates manufacturers to invest in battery cycling stations to cycle cells several times before sending them to market, consuming both time and resources. Second, irreversible capacity consumed during the formation period is lost to the battery, directly subtracting from the system's energy. Last, the formation period generates gases which under some conditions may need to be vented prior to further operation of the cell. Research efforts worldwide continue to generate very high capacity carbon electrode materials having high irreversible capacities. To utilize these materials in the most efficient manner requires a prepassivation or prelithiation scheme not involving the sacrifice of a substantial quantity of the cyclable lithium available in the positive electrode. Although several research groups have been studying these processes and potential alternative approaches, there is no known solution for eliminating the formation period in an economically feasible manner.
Overcharge Phenomena
Under conditions of overcharge, major capacity losses have been observed in all types of lithium-ion cells. The poor overcharge resistance of commercial lithium-ion cells and the safety issues 到。
由于经济方面的影响，化成在电池制作过程非常关键，因为制造商有义务花钱对电池进行化成循环直到电池容量稳定，消耗时间物力。其次，化成过程不可逆容量损失，直接将会在电池体系能量里减去。最后，化成过程产生了气体，需要被释放，然后电池才能运作。世界范围内的研究工作都在继续寻找高容量的碳负极材料，有更高的不可逆容量。为了高效利用这些材料，需要预先钝化和锂化，并且不消耗正极材料循环需要的锂量。尽管一些研究组已经研究了这些过程和潜在的代替方法，但是仍然没有找到经济上可行的能够消除化成过程的方法。
过充现象
很多电池在过充条件下都观察到容量损失的现象。由于过充引起的商用锂离子电池的耐过充性和安全性，已经导致
that result from overcharge have led to tight co:ntrol over charging and discharging of commercial cells using built-in electronic circuitry. The future application cf lithium-ion cells in new areas would be facilitated by advances in understanding and controlling overcharge. In particular the use of lithium-ion cells in multicell bipolar stacks requires a greater degree of overcharge tolerance due to the difficulty in achieving uniform utilization of all cells in series stacks.
Overcharge losses can be classified into three main types at present: (i) overcharge of coke and graphite-based negative electrodes, (ii) overcharge reactions for high-voltage positive electrodes, and (iii) overcharge/high-voltage electrolyte oxidation processes. These side reactions lead to loss of the active material and consumption of electrolyte, both of which can lead to capacity loss in the cell.
Overcharge of Coke and Graphite-Based Negative Electrodes
During overcharge of lithium-ion cells, metallic lithium may be deposited on the negative electrode surface as the primary side reaction. This reaction is expected for cells with excess cyclable lithium due to either higher than desired initial mass ratio or lower than expected lithium losses during the formation period. The freshly deposited lithium covers the active surface area of the 了严格控制过充和过放。未来锂离子电池在不同领域的运用，将会促进对锂离子电池的理解以及对电池过充的控制。尤其是锂电池在多单元双栈方面的应用更需求电池的耐过充性，这导致了所有规格电池在多双栈利用有相当大的困难。
过充损失可以归为三种类型，(i) 碳负极和石墨负极电极的过充；(ii)高电压下正极的过充反应；(iii)高电压条件下电解质的氧化过充反应。这些副反应导致了活性物质的损失和电解质的消耗，这两种都会导致电池的容量衰减。
碳和石墨负极电极的过充
在锂离子电池过充过程，最初发生的副反应是金属锂沉积在负极表面。在化成过程中，循环锂过量，不管是高于理想的物质量比还是低于最初锂损失量，这个反应是人们所期望的。最开始的沉积锂覆盖在负极活性物质表面的区域导致了
红外数据通信技术外文翻译文献(文档含中英文对照即英文原文和中文翻译) Infrared Remote Control System Abstract Red outside data correspondence the technique be currently within the scope of world drive extensive usage of a kind of wireless conjunction technique, drive numerous hardware and software platform support. Red outside the transceiver product have cost low, small scaled turn, the baud rate be quick, point to point SSL, be free from electromagnetism thousand Raos
etc. characteristics, can realization information at dissimilarity of the product fast, convenience, safely exchange and transmission, at short distance wireless deliver aspect to own very obvious of advantage. Along with red outside the data deliver a technique more and more mature, the cost descend, red outside the transceiver necessarily will get at the short distance communication realm more extensive of application. The purpose that design this system is transmit customer’s operation information with infrared rays for transmit media, then demodulate original signal with receive circuit. It use coding chip to modulate signal and use decoding chip to demodulate signal. The coding chip is PT2262 and decoding chip is PT2272. Both chips are made in Taiwan. Main work principle is that we provide to input the information for the PT2262 with coding keyboard. The input information was coded by PT2262 and loading to high frequent load wave whose frequent is 38 kHz, then modulate infrared transmit dioxide and radiate space outside when it attian enough power. The receive circuit receive the signal and demodulate original information. The original signal was decoded by PT2272, so as to drive some circuit to accomplish customer’s operation demand. Keywords: Infrared dray；Code；Decoding；LM386；Red outside transceiver 1 Introduction 1.1 research the background and significance Infrared Data Communication Technology is the world wide use of a wireless connection technology, by the many hardware and software platforms supported. Is a data through electrical pulses and infrared optical pulse switch between the wireless data transceiver technology.
Circuit breaker 断路器 Compressed air circuit breaker is a mechanical switch equipm ent, can be i 空气压缩断路器是一种机械开关设备，能够在n normal and special conditions breaking current (such as sho rt circuit cur 正常和特殊情况下开断电流（比如说短路电流）。 rent). For example, air circuit breaker, oil circuit breaker, interf erence circ 例如空气断路器、油断路器，干扰电路的导体uit conductor for the application of the safety and reliability o f the circuit 干扰电路的导体因该安全可靠的应用于其中， breaker, current in arc from is usually divided into the followin g grades: a 电流断路器按灭弧远离通常被分为如下等级：ir switch circuit breaker, oil circuit breaker, less oil circuit break er, compr 空气开关断路器、油断路器、少油断路器、压缩空essed air circuit breaker, a degaussing of isolating switch, six s ulfur hexaf
重庆大学网络教育学院 学生毕业设计（论文）开题报告 一、课题的目的及意义（含国内外的研究状况分析）： 近年来，随着国民经济的发展，市场竞争日益加大，再加上中国加入世贸组织，国 门逐渐打开，越来越多的国外企业在中国的市场上发展壮大，抢夺市场占有份额，对国内企业 造成了很大的冲击，特别是中小企业更难立足和发展，因此提高我们企业的竞争力迫在眉睫。 我们都是知道人才对于企业的生存和发展都有着重要的意义，并起着越来越重要的作用， 尤其对于我国的中小企业而言，由于其财力、物力有限，不可能与大企业比资金、比实力，因 而人才，尤其是优秀的人才对我国的中小企业的生存与发展就有着决定性的作用。但是，由于 社会、历史和自身等诸多因素的影响，人才在我国的中小企业中往往难以发挥自己的才能，人 才流失现象相当严重，往往自己培养的核心员工成为别人的得意助手，给企业带来了不可估量 的损失。中小企业如果想要获得长足发展必须在人才方面下功夫，应该将人才战略作为整个 企业发展战略的核心，但是中小企业在人才引进、聘用、培育、留守方面存在着种种的不利和 弊端，这些直接导致了企业请进了人才而又留不住人才的尴尬局面的出现。因此如何留住人才， 如何解决人才流失这一问题就显得尤为必要。 二、课题任务、重点研究内容、实现途径、条件： 本文主要利用文献研究方法，通过多种途径收集有关中小企业人才流失现状及对策的文献 资料。主要包括相关著作、期刊杂志以及相关网站查找资料，收集数据等多个关于人才流失的 的相关著作及论文，收集我国关于中小企业相关的文献资料及法律法规等。通过搜集和整理大 量的与中小企业人才流失相关的资料，在指导老师的指导和帮助下，分析中小企业在人力资源 管理中的人才流失问题，找出原因，并结合自己所学的知识、收集的资料并整理消化写成论文。 通过新颖的论点和想法来提出自己论文的创新点，并运用所学习的知识来补充和加工。本文 先阐述课题背景和目的，从而引出人才流失的研究现状，结合现状并运用课题的研究方法来分
华北电力大学科技学院 毕业设计（论文）附件 外文文献翻译 学号：121912020115姓名：彭钰钊 所在系别：动力工程系专业班级：测控技术与仪器12K1指导教师：李冰 原文标题：Infrared Remote Control System Abstract 2016 年 4 月 19 日
红外遥控系统 摘要 红外数据通信技术是目前在世界范围内被广泛使用的一种无线连接技术，被众多的硬件和软件平台所支持。红外收发器产品具有成本低，小型化，传输速率快，点对点安全传输，不受电磁干扰等特点，可以实现信息在不同产品之间快速、方便、安全地交换与传送，在短距离无线传输方面拥有十分明显的优势。红外遥控收发系统的设计在具有很高的实用价值，目前红外收发器产品在可携式产品中的应用潜力很大。全世界约有1亿5千万台设备采用红外技术，在电子产品和工业设备、医疗设备等领域广泛使用。绝大多数笔记本电脑和手机都配置红外收发器接口。随着红外数据传输技术更加成熟、成本下降，红外收发器在短距离通讯领域必将得到更广泛的应用。 本系统的设计目的是用红外线作为传输媒质来传输用户的操作信息并由接收电路解调出原始信号，主要用到编码芯片和解码芯片对信号进行调制与解调，其中编码芯片用的是台湾生产的PT2262，解码芯片是PT2272。主要工作原理是：利用编码键盘可以为PT2262提供的输入信息，PT2262对输入的信息进行编码并加载到38KHZ的载波上并调制红外发射二极管并辐射到空间，然后再由接收系统接收到发射的信号并解调出原始信息，由PT2272对原信号进行解码以驱动相应的电路完成用户的操作要求。 关键字：红外线；编码；解码；LM386；红外收发器。 1 绪论
用于多跳认知无线电网络的分布式网络编码控制信道 Alfred Asterjadhi等著 1 前言 大多数电磁频谱由政府机构长期指定给公司或机构专门用于区域或国家地区。由于这种资源的静态分配，许可频谱的许多部分在许多时间和/或位置未使用或未被充分利用。另一方面，几种最近的无线技术在诸如IEEE802.11，蓝牙，Zigbee之类的非许可频段中运行，并且在一定程度上对WiMAX进行操作;这些技术已经看到这样的成功和扩散，他们正在访问的频谱- 主要是2.4 GHz ISM频段- 已经过度拥挤。为了为这些现有技术提供更多的频谱资源，并且允许替代和创新技术的潜在开发，最近已经提出允许被许可的设备（称为次要用户）访问那些许可的频谱资源，主要用户未被使用或零星地使用。这种方法通常被称为动态频谱接入（DSA），无线电设备发现和机会性利用未使用或未充分利用的频谱带的能力通常称为认知无线电（CR）技术。 DSA和CR最近都引起了无线通信和网络界的极大关注。通常设想两种主要应用。第一个是认知无线接入（CW A），根据该认知接入点，认知接入点负责识别未使用的许可频谱，并使用它来提供对次用户的接入。第二个应用是我们在这个技术中研究的应用，它是认知自组织网络（CAN），也就是使用 用于二级用户本身之间通信的无许可频谱，用于诸如点对点内容分发，环境监控，安全性等目的，灾难恢复情景通信，军事通信等等。 设计CAN系统比CW A有更多困难，主要有两个原因。第一是识别未使用的频谱。在CW A中，接入点的作用是连接到互联网，因此可以使用简单的策略来推断频谱可用性，例如查询频谱调节器在其地理位置的频谱可用性或直接与主用户协商频谱可用性或一些中间频谱经纪人另一方面，在CAN中，与频谱调节器或主要用户的缺乏直接通信需要二级用户能够使用检测技术自己识别未使用的频谱。第二个困难是辅助用户协调媒体访问目的。在CW A中存在接入点和通常所有二级用户直接与之通信（即，网络是单跳）的事实使得直接使用集中式媒体接入控制（MAC）解决方案，如时分多址（TDMA）或正交频分多址（OFDMA）。相反，预计CAN将跨越多跳，缺少集中控制器;而对于传统的单通道多跳自组织网络而言，这个问题的几个解决方案是已知的，因为假设我们处理允许设备访问的具有成
外文原文 Mechanical Design Abstract: A machine is a combination of mechanisms and other components which transforms, transmits. Examples are engines, turbines, vehicles, hoists, printing presses, washing machines, and movie cameras. Many of the principles and methods of design that apply to machines also apply to manufactured articles that are not true machines. The term "mechanical design" is used in a broader sense than "machine design" to include their design. the motion and structural aspects and the provisions for retention and enclosure are considerations in mechanical design. Applications occur in the field of mechanical engineering, and in other engineering fields as well, all of which require mechanical devices, such as switches, cams, valves, vessels, and mixers. Keywords: Mechanical Design mechanisms Design Process The Design Process Designing starts with a need real.Existing apparatus may need improvements in durability, efficiency, weight, speed, or cost. New apparatus may be needed to perform a function previously done by men, such as computation, assembly, or servicing. With the objective wholly or partly In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts. When the general shape and a few dimensions of the several components become
对行销售人员激励机制分析 1激励机制的描述 1.1激励理论主要是研究激发人们行为动机的各种因素。由于人类行为 的原动力是需要，因此这种理论实际上就是围绕着人们的各种需要来进行研究。主要包括马斯洛的赫茨伯格的双因素理论、奥尔德弗的“ERG”理论、需要层次理论和麦克利兰的成就需要激励理论。 1.2 过程型激励理论重点研究人从动机产生到采取行动的心理过程。 包括亚当斯的公平理论、佛隆的期望理论和斯金纳的强化理论。 二对行销售人员激励机制分析 美国心理学家佛隆在1964年首先提出期望理论，人之所以能够完成某项工作并达成组织目标，因为这些组织目标和工作会帮助他们达成自己的目标。根据期望理论，某一活动对某人的激发力量取决于他所能得到的结果的全部预期价值乘以他认为达成该结果的期望概率。这就要求要处理好三个方面的关系：绩效与奖励的关系、努力与绩效的关系、奖励与个人需要的关系，任何一个环节都不能出现问题，否则都会导致无效激励。 从以期望理论为代表的过程型激励理论与内容型激励理论的观点来看，激励过程的科学性和合理性、激励手段对销售人员个性化需求的满足程度构成了激励的两要素。由此看出，销售人员的激励机制确实有改进的必要。 三销售人员激励体制中不足原因 3.1激励方式单一，过分依靠货币等物质激励手段而忽视精神激励的重要作用，销售人员没有归属感，缺少团队凝聚力。即使在物质激励方面，也是“佣金制”和“提成制”的天下，收入的多少完全依据销售额或利润额的多少，无视死去差异和个人实际努力程度，激励不公现象十分普遍。 3.2晋升制度僵硬，论资排辈，讲资历而忽视能力，讲关系而忽视业务水平，人浮于事，优秀人才流失严重，已不再适应市场竞争的需要。 3.3多数企业没有完整的培训激励机制，企业只注重“挖人”而非培养，因而满足不了销售人员自我发展的需要。
5G无线通信网络中英文对照外文翻译文献(文档含英文原文和中文翻译)
翻译： 5G无线通信网络的蜂窝结构和关键技术 摘要 第四代无线通信系统已经或者即将在许多国家部署。然而，随着无线移动设备和服务的激增，仍然有一些挑战尤其是4G所不能容纳的，例如像频谱危机和高能量消耗。无线系统设计师们面临着满足新型无线应用对高数据速率和机动性要求的持续性增长的需求，因此他们已经开始研究被期望于2020年后就能部署的第五代无线系统。在这篇文章里面，我们提出一个有内门和外门情景之分的潜在的蜂窝结构，并且讨论了多种可行性关于5G无线通信系统的技术，比如大量的MIMO技术，节能通信，认知的广播网络和可见光通信。面临潜在技术的未知挑战也被讨论了。 介绍 信息通信技术（ICT）创新合理的使用对世界经济的提高变得越来越重要。无线通信网络在全球ICT战略中也许是最挑剔的元素，并且支撑着很多其他的行业，它是世界上成长最快最有活力的行业之一。欧洲移动天文台（EMO）报道2010年移动通信业总计税收1740亿欧元,从而超过了航空航天业和制药业。无线技术的发展大大提高了人们在商业运作和社交功能方面通信和生活的能力无线移动通信的显著成就表现在技术创新的快速步伐。从1991年二代移动通信系统(2G)的初次登场到2001年三代系统（3G）的首次起飞，无线移动网络已经实现了从一个纯粹的技术系统到一个能承载大量多媒体内容网络的转变。4G无线系统被设计出来用来满足IMT-A技术使用IP面向所有服务的需求。在4G系统中，先进的无线接口被用于正交频分复用技术（OFDM），多输入多输出系统（MIMO）和链路自适应技术。4G无线网络可支持数据速率可达1Gb/s的低流度，比如流动局域无线访问，还有速率高达100M/s的高流速，例如像移动访问。LTE系统和它的延伸系统LTE-A，作为实用的4G系统已经在全球于最近期或不久的将来部署。 然而，每年仍然有戏剧性增长数量的用户支持移动宽频带系统。越来越多的
1、 外文原文 A: Fundamentals of Single-chip Microcomputer Th e si ng le -c hi p m ic ro co mp ut er i s t he c ul mi na ti on of both t h e de ve lo pm en t o f t he d ig it al co m pu te r an d th e i n te gr at ed c i rc ui t a rg ua bl y t h e to w m os t s ig ni f ic an t i nv en ti on s o f t he 20th c e nt ur y [1]. Th es e t ow ty pe s of ar ch it ec tu re a re fo un d i n s in g le -ch i p m i cr oc om pu te r. So m e em pl oy t he spl i t pr og ra m/da ta m e mo ry o f th e H a rv ar d ar ch it ect u re , sh ow n in Fi g.3-5A -1, o th ers fo ll ow t he p h il os op hy , wi del y a da pt ed f or ge n er al -p ur po se co m pu te rs a nd m i cr op ro ce ss o r s, o f ma ki ng n o log i ca l di st in ct ion be tw ee n p r og ra m an d d at a m e mo ry a s i n t he P r in ce to n ar ch ite c tu re , sh ow n i n F ig.3-5A-2. In g en er al te r ms a s in gl e -chi p m ic ro co mp ut er i s c h ar ac te ri ze d b y t h e i nc or po ra ti on o f a ll t he un it s of a co mp uter i n to a s in gl e d ev i ce , as s ho wn in Fi g3-5A -3. Fig.3-5A-1 A Harvard type Program memory Data memory CPU Input& Output unit memory CPU Input& Output unit
《文献检索》课程教学设计 目录 绪论：文献（信息）检索的意义及基础 (2) 项目一科技文献检索方法和图书馆的科学利用 (8) 项目二常见化学化工科技论文的写作 (11) 项目三美国化学文摘的使用 (14) 项目四专利文献的查询 (17) 项目五标准文献的查询 (20) 项目六计算机信息检索的应用 (23) 项目七信息检索策略综合应用训练 (26)
徐州工业职业技术学院教学设计（讲稿）
教学内容与设计 绪论：文献（信息）检索的意义及基础 自我介绍 提问一：你会检索吗？ 如果会，那么会用检索以下毕业专题的相关资料吗？ ?杜仲叶中绿原酸的提取分离 ?有机废水处理工艺设计 ?蚕丝蛋白制备工艺研究 ?铁矿石含铁量测定方法新工艺 ?基因工程干扰素生产工艺研究 提问的目的：突出检索技术直接是为毕业专题服务，这是一门技术。提问二：信息检索课是什么？ 学生如是说： 文献检索课程是井底之蛙的升降机，是雄鹰的翅膀，是横跨天堑的桥梁。 针对某一课题，通过电子检索查阅有关资料，才知道知识的浩瀚，才知道世界的宽广，才知道“山外青山，楼外楼”。 它是我在大学期间所学的最重要，最有用的课程之一，有了它，我们将会受益终生。教会我们一种方法，一种主动 了解外界，提高自己，放眼世界的方法。 检索不仅是我们学习的制胜法宝，更是一条贯穿我们生活的红线。正因为有了这门课的学习，现在大脑的检索意识 就比较强烈，越搜越快！前几天，问同学借自行车，他告 诉我车子大致地点，是永久牌，有车栏，略有一点蓝。到 了现场，脑海中一下就有了先找有栏的，再找蓝颜色的， 最后确定是不是永久的，很快就找到了。 我爱检索，就像爱自己的生命一样。 最后我想说，我们是幸运的！我们学到了一门真正有用的课，它对我的影响和帮助将是伴随我一身的。 提问三：借鉴与创新的关系？ 科学研究是“站在前人肩膀上”的事业，而创新又是科学研究的灵魂，即要求“前无古人”。 时间分配 2min 引导学生回答 8min 10min 通过往届学生对信息检索课的评价能够激起学生学习这门课的兴趣，也可以突出这门课对个人的作用。 10min 通过提问让学生
无线数据采集和传输系统外文翻译文献 (文档含中英文对照即英文原文和中文翻译) 译文： 一种无线数据采集和传输系统的设计【摘要】在现代无线通信领域主要有一些技术为无线传输网络提供解决方法，例如：GSM，CDMA，3G，Wi-Fi。这些方法使得网络能够高效率和高质量的工作，但是成本很高。因此要低成本和在没有基础设施或者基础设施被破坏的情况下推广它们是很困难的。根据这种情况，本论文中数据采集和无线传输网络里的信息终端和无线收发模块的关键部件，是依据nRF905收发模块和51系列单片机的原理设计而成作为核心硬件，此外，结合目前自组无线网络的技术，可以构建一个短距离无
线数据采集和传输网络，这个网络能够提供一个工作在ISM（工业科学医学）频段的低功率及高性能的数据通信系统。然后提出了一个对无线通信可行的解决方案，这个方案优势在于更强的实时响应，更高的可靠性要求和更小的数据量。通过软件和硬件的调试和实际测量，这个系统在我们的解决方案基础上运行良好，达到了预期的目标并且已经成功的应用到无线车辆系统。 【关键词】自组网络；数据采集；传输网络 1 简介 在现代无线通信里，GSM，CDMA，3G和Wi-Fi因为其高速和可靠的质量而逐渐成为无线数据传输网络的主流解决方案。它们也有高成本的缺点，因此如果广泛的应用，将会引起大量的资源浪费，也不能在小区域，低速率的数据通信中得到提升。多点短距离无线数据采集和传输网络将成为最佳解决方案。此系统支持点对点，点对多点和多点对多点通信系统的发展。 短距离无线通信可以适应各种不同的网络技术，例如蓝牙， IEEE802.11，家庭无线网和红外。与远距离无线通信网络相比，它们的不同之处在于基本结构，应用水平，服务范围和业务（数据，语音）。设计短距离无线通信网络的最初目的是为了提供短距离宽带无线接入到移动环境或者制定临时网络，这是在移动环境里互联网更深的发展。短距离无线通信网络最主要的优势是更低的成本和更灵活的应用。 本文介绍信息终端（单个器件）的硬件和软件以及多点短距离无线数据采集和传输网络的无线接收模块的设计建议，提供一个低功率高性
中英文翻译 附件1：外文资料翻译译文 通用移动通信系统的回顾 1.1 UMTS网络架构 欧洲/日本的3G标准，被称为UMTS。 UMTS是一个在IMT-2000保护伞下的ITU-T 批准的许多标准之一。随着美国的CDMA2000标准的发展，它是目前占主导地位的标准，特别是运营商将cdmaOne部署为他们的2G技术。在写这本书时，日本是在3G 网络部署方面最先进的。三名现任运营商已经实施了三个不同的技术：J - PHONE 使用UMTS，KDDI拥有CDMA2000网络，最大的运营商NTT DoCoMo正在使用品牌的FOMA（自由多媒体接入）系统。 FOMA是基于原来的UMTS协议，而且更加的协调和标准化。 UMTS标准被定义为一个通过通用分组无线系统（GPRS）和全球演进的增强数据
技术（EDGE）从第二代GSM标准到UNTS的迁移，如图。这是一个广泛应用的基本原理，因为自2003年4月起，全球有超过847万GSM用户，占全球的移动用户数字的68％。重点是在保持尽可能多的GSM网络与新系统的操作。 我们现在在第三代（3G）的发展道路上，其中网络将支持所有类型的流量：语音，视频和数据，我们应该看到一个最终的爆炸在移动设备上的可用服务。此驱动技术是IP协议。现在，许多移动运营商在简称为2.5G的位置，伴随GPRS的部署，即将IP骨干网引入到移动核心网。在下图中，图2显示了一个在GPRS网络中的关键部件的概述，以及它是如何适应现有的GSM基础设施。 SGSN和GGSN之间的接口被称为Gn接口和使用GPRS隧道协议（GTP的，稍后讨论）。引进这种基础设施的首要原因是提供连接到外部分组网络如，Internet或企业Intranet。这使IP协议作为SGSN和GGSN之间的运输工具应用到网络。这使得数据服务，如移动设备上的电子邮件或浏览网页，用户被起诉基于数据流量，而不是时间连接基础上的数据量。3G网络和服务交付的主要标准是通用移动通信系统，或UMTS。首次部署的UMTS是发行'99架构，在下面的图3所示。 在这个网络中，主要的变化是在无线接入网络（RAN的）CDMA空中接口技术的引进，和在传输部分异步传输模式作为一种传输方式。这些变化已经引入，主要是为了支持在同一网络上的语音，视频和数据服务的运输。核心网络保持相对不变，主要是软件升级。然而，随着目前无线网络控制器使用IP与3G的GPRS业务支持节点进行通信，IP协议进一步应用到网络。 未来的进化步骤是第4版架构，如图4。在这里，GSM的核心被以语音IP技术为基础的IP网络基础设施取代。 海安的发展分为两个独立部分：媒体网关（MGW）和MSC服务器（MSS）的。这基本上是打破外连接的作用和连接控制。一个MSS可以处理多个MGW，使网络更具有扩展性。 因为现在有一些在3G网络的IP云，合并这些到一个IP或IP/ ATM骨干网是很有意义的（它很可能会提供两种选择运营商）。这使IP权利拓展到整个网络，一直到BTS(基站收发信台)。这被称为全IP网络，或推出五架构，如图五所示。在HLR/ VLR/VLR/EIR被推广和称为HLR的子系统（HSS）。 现在传统的电信交换的最后残余被删除，留下完全基于IP协议的网络运营，并
POWER SUPPLY AND DISTRIBUTION SYSTEM ABSTRACT The basic function of the electric power system is to transport the electric power towards customers. The l0kV electric distribution net is a key point that connects the power supply with the electricity using on the industry, business and daily-life. For the electric power, allcostumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable.To improve the reliability of the power supply network, we must increase the investment cost of the network construction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balance point to make the most economic,between the investment and the loss by calculating the investment on power net and the loss brought from power-off. KEYWARDS：power supply and distribution,power distribution reliability，reactive compensation,load distribution
外文文献—动画
Animation Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions to create an illusion of movement. The effect is an optical illusion of motion due to the phenomenon of persistence of vision, and can be created and demonstrated in several ways. The most common method of presenting animation is as a motion picture or video program, although there are other methods. Early examples An Egyptian burial chamber mural, approximately 4000 years old, showing wrestlers in action. Even though this may appear similar to a series of animation drawings, there was no way of viewing the images in motion. It does, however, indicate the artist's intention of depicting motion. Five images sequence from a vase found in Iran There is no single person who can be considered the "creator" of film animation, as there were several people working on projects which could be considered animation at about the same time. Georges Méliès was a creator of special-effect films; he was generally one of the first people to use animation with his technique. He discovered a technique by accident which was to stop the camera rolling to change something in the scene, and then continue rolling the film. This idea was later known as stop-motion animation. Early examples of attempts to capture the phenomenon of motion drawing can be found in paleolithic cave paintings, where animals are depicted with multiple legs in superimposed positions, clearly attempting to convey the perception of motion. An Egyptian burial chamber mural , approximately 4000 years old, showing wrestlers in action. Even though this may appear similar to a series of animation drawings, there was no way of viewing the images in motion. It does, however, indicate the artist's intention of depicting motion. A 5,000 year old earthen bowl found in Iran.It has five images of a goat painted along the sides. This has been claimed to be an example of early animation. However, since no equipment existed to show the images in motion, such a series of images cannot be called animation in a true sense of the word. A Chinese zoetrope-type device had been invented in 180 AD. The phenakistoscope, praxinoscope, and the common flip book were early popular animation devices invented during the 19th century. These devices produced the appearance of movement from sequential drawings using technological means, but animation did not really develop much
吸引和留住人才 来自：《承包商工具和供应》 吸引和留住人才的重要性 十多年前，美国一些先进的公司就预言将会出现严重的人力资源短缺问题。这样的预言在当今竞争越来越激烈的商界中已经得到验证。人力资源短缺几乎能影响所有的行业，因此企业雇主应当跳出传统陈旧的人力资源配置概念。当“新手”雇员加入工作岗位，必然有各种问题随之产生。因此，吸引和留住企业中的优秀雇员十分重要。高效率的雇员就是令人满意的雇员。这样的人能为企业创造更好的业绩。企业管理者有责任不断地营造能让人才乐意工作于其中的企业环境。 首先要确保新招募的雇员的素质，认定及留住资深雇员，再者就是发展有成长潜力的雇员。同时要关注表现欠佳的雇员，去了解这类员工是否分配到了不适当的工作岗位，明确公司有无提供具体清晰的工作要求让员工清楚自己的工作职责。如果员工的表现没有达到预期的要求，企业管理者应明确的反馈给员工知道。 大卫?格罗斯是Power&Control Automation 公司的客户代表。该公司是西门子公司在美国佛罗里达州和佐治亚州的主要分销商。他提出以下观点：“一个出色雇员的特点是忠诚，有责任心，有创意，注重细节——这是最重要也最难得的特性。除了福利和报酬之外，雇员还需要对公司有一份信心。他们希望确定为公司销售的产品是安全无害的，希望确定公司会在业界保持稳固地位。 格罗斯认为安全感是区分好企业与坏企业的一大特点。“优秀的雇员具有积极的态度和可培训性，他们有良好的工作记录，能与他们合作融洽。作为小型企业，我们可以更加灵活，并且我们很自豪能给雇员提供家庭般和谐友好的氛围，较有自我管理的风格。我们允许雇员处理个人事情但在过后补上该工作时间，我们提供的整套福利也很有竞争力。 优秀员工对公司的期望 任何行业任何公司里的雇员都对公司有以下几个方面的需求，以下各方面是根据重要性和受重视的程度降序排列的。 1、乐趣：工作的乐趣包括期待上班工作以及下班时感觉良好。具体的雇员对此有具体的不同感受。工作的乐趣对于雇员来说可能来自工作中的创意，成功的完成任务，看到自己的工作得到积极向上的结果，知道自己为别人做了一些贡献，或者得到来自他人的尊敬和认可。一个有创意的雇员会因为他的创意而成为一个高效率的人才。一个细心的雇员会乐意细致钻研。如果将一个技术骨干推到管理层的职位，则未必能令他成为一个高效率的人才。岗位责任分工与个人能力应当合理结合，才能实现最高的工作效率。
无线局域网技术外文翻译文献(文档含中英文对照即英文原文和中文翻译) 翻译： 无线局域网技术 最近几年，无线局域网开始在市场中独霸一方。越来越多的机构发现无线局域网是传统有线局域网不可缺少的好帮手，它可以满足人们对移动、布局变动和自组网络的需求，并能覆盖难以铺设有线网络的地域。无线局域网是利用无线传输媒体的局域网。就在前几年，人们还很少使用无线局域网。原因包括成本高、数据率低、职业安全方面的顾虑以及需要许可证。随着这些问题的逐步解决，无线局域网很快就开始流行起来了。 无线局域网的应用 局域网的扩展 在20世纪80年代后期出现的无线局域网早期产品都是作为传统有线局域网替
代品而问世的。无线局域网可以节省局域网缆线的安装费用，简化重新布局和其他对网络结构改动的任务。但是，无线局域网的这个动机被以下一系列的事件打消。首先，随着人们越来越清楚地认识到局域网的重要性，建筑师在设计新建筑时就包括了大量用于数据应用的预先埋设好的线路。其次，随着数据传输技术的发展，人们越来越依赖于双绞线连接的局域网。特别是3类和5类非屏蔽双绞线。大多数老建筑中已经铺设了足够的3类电缆，而许多新建筑里则预埋了5类电缆。因此，用无线局域网取代有线局域网的事情从来没有发生过。 但是，在有些环境中无线局域网确实起着有线局域网替代品的作用。例如，象生产车间、股票交易所的交易大厅以及仓库这样有大型开阔场地的建筑；没有足够双绞线对，但又禁止打洞铺设新线路的有历史价值的建筑；从经济角度考虑，安装和维护有线局域网划不来的小型办公室。在以上这些情况下，无线局域网向人们提供了一个有效且更具吸引力的选择。其中大多数情况下，拥有无线局域网的机构同时也拥有支持服务器和某些固定工作站的有线局域网。因此，无线局域网通常会链接到同样建筑群内的有线局域网上。所以我们将此类应用领域成为局域网的扩展。 建筑物的互连 无线局域网技术的另一种用途是邻楼局域网之间的连接，这些局域网可以是无线的也可以是有线的。在这种情况下，两个楼之间采用点对点的无线链接。被链接的设备通常是网桥或路由器。这种点对点的单链路从本质上看不是局域网，但通常我们也把这种应用算作无线局域网。 漫游接入 漫游接入提供局域网和带有天线的移动数据终端之间的无线链接，如膝上型电脑和笔记本电脑。这种应用的一个例子是从外地出差回来的职员将数据从个人移动电脑传送到办公室的服务器上。漫游接入在某种延伸的环境下也是十分有用的，如在建筑群之外操作的一台电脑或一次商务行为。在以上两种情况下，用户会带着自己的电脑随意走动，并希望可以从不同的位置访问有线局域网上的服务器。 自组网络 自组网络（ad hoc network）是为了满足某些即时需求而临时而建立的一种对等网络（没有中央服务器）例如，有一群职员，每人带着一台膝上电脑或掌上电脑，