【作者】 王可；

【导师】 杨军； 解晶莹；

【作者基本信息】 中国科学院研究生院（上海微系统与信息技术研究所） ， 材料物理与化学， 2003， 博士

【摘要】 石墨类碳材料因具有良好的可逆嵌脱锂性能而在目前的锂离子电池中得以广泛应用。然而该类材料的嵌脱锂容量较低（理论容量372mAh／g），难以满足高能量密度电池的要求，因此开发高性能的负极材料是当务之急。 本论文采用高能球磨法（机械化学过程）制备了一系列锂金属氮化物和金属磷化物，并对其脱嵌锂特性等电化学性能进行了研究，同时对一些Ⅲ-Ⅴ族化合物半导体材料和硒化物半导体材料的脱嵌锂特性进行了初步探讨。 研究发现氮气气氛有利于高能球磨法制备锂金属氮化物材料。在三元锂金属氮化物Li_3-xM_xN（M=Co，Cu，Ni）中以Li_2.6Co_0.4N有着最高的容量，前10次循环可逆脱嵌锂容量高达880mAh／g。用Cu、Fe部分取代Co的Li_2.6Co_0.2Cu_0.2N和Li_2.6Co（0.2）Fe_0.2N材料脱嵌锂容量有所降低，然而在循环性能方面有了较大的改善。而将Co完全取代的Li_2.6Ni_0.2CH_0.2N材料的电化学性能相对较差。此类氮化物材料首次脱锂时从晶态转变为无定形态，随后的嵌脱锂过程保持该无定形态。这种无定形态允许大量锂离子的脱嵌，但是在最初的几个循环会发生结构重排。材料的电化学活性与其本身的微结构（比如脱锂后的结构排序等）密切相关。 CuP₂材料首次嵌锂过程对应于Cu的还原和Li₃P的产生，随后的脱锂过程呈现三步反应，对应于Li₂CuP等新相的形成。其脱嵌锂机理与CoP₃和MnP₄不同，其中Cu和P在氧化还原过程中都起着重要作用。而加入Li₃N为反应物制备的三元磷化物Li_1.75Cu_1.25P₂材料有效地消除了CuP₂材料的首次不可逆容量，首次脱嵌锂容量750mAh／g左右，充放电效率为100％，其脱嵌锂机理与CuP₂类似。 GaAs、GaSb、InP和InAs的脱嵌锂特性比较相似，充放电过程可能对应于合金化与去合金化过程。而SnSe和PbSe的脱嵌锂恃性与各自的氧化物类似。更多还原

【Abstract】 Graphite-based carbonaceous materials have been widely used as the anode material of commercial lithium-ion batteries for its excellent cycleability. With the growing demands of high-energy secondary batteries, the low capacity of graphite (theoretical capacity: 372 mAh/g) has been thought to be a limiting factor for the wide applications. Therefore, a great deal of effort has been put into research on high-performance anode materials for lithium ion batteries.In this study, two series of lithium metal nitrides and phosphides were synthesized by high-energy ballmilling technique (mechanochemical synthesis). Their electrochemical properties and reaction mechanisms with lithium were investigated. In addition, the charge and discharge characteristics of some semiconductor materials were also studied.The test results show that nitrogen atmosphere is favorable for the ball-milling synthesis of lithium metal nitrides. Of the many ternary lithium metal nitrides Li3-xMxN (M=Co, Cu, Ni), Li2.6Co0.4N shows the highest specific capacity which is about 880mAh/g in the first 10 cycles. Li2.6Co0.2Cu0.2N and Li2.6Coo.2Fe0.2N have a lower capacity but much better cycle life than Li2.6Co0.4N, in which part of Co is substituted by Cu or Fe. By contrast, Li2.6Ni0.2Cu0.2N presents worse electrochemical reversibility than Li2.6Co0.2Cu0.2N. The structure of all these nitrides changes from the crystalline to the amorphous phase in the first lithium extraction process. The amorphous state is maintained during subsequent cycles, which is the reason for the very large capacity. However, it undergoes the structure rearrangement in the initial cycles. The electrochemical reactivity of lithium metal nitrides is strongly influenced by the micro-structures (e.g. short-range ordering after the first lithium extraction).The first lithium insertion into the CuP2 phase leads to copper reduction and theformation of lithium phosphide . The subsequent lithium extraction presents three voltage plateaus related to the formation of new phases such as Li2CuP. It means that both copper and phosphorus face a change of the oxic ation state for the electrochemical insertion and extraction. Lithium copper phosphide exhibits a similar reaction process. It provides a reversible capacity of 750 mAh/g and faradic yield of 100% at the first cycle.The electrochemical characteristics of GaAs, GaSb, InP and InAs are greatly similar. The charge and discharge behavior probably corresponds to alloying and de-alloying process. The reaction mechanism of SnSe and PbSe with lithium is similar to that of the respective oxides.更多还原