新型高能量密度锂离子电池负极Li(21)Si5/石墨烯复合材料的合成与性能研究  

Synthesis and Property of Novel Li_(21)Si_5/Graphene Composites Anode for High Energy Lithium-ion Batteries

作　　者：杨科 侯超[1] 宋晓艳[1] YANG Ke;HOU Chao;SONG Xiao-Yan(Key Laboratory of Advanced Functional Materials,Education Ministry of China,College of Materials Science and Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学材料科学与工程学院,新型功能材料教育部重点实验室,北京100124

出　　处：《无机材料学报》2018年第10期1065-1069,共5页Journal of Inorganic Materials

基　　金：北京市自然科学基金(2174066);国家杰出青年科学基金(51425101)

摘　　要：本研究利用放电等离子烧结技术同时实现热化学锂化与致密化,制备得到Li_(21)Si_5与石墨烯两相分布均匀、高致密度的纳米结构复合材料。石墨烯的二维结构、优异的电导率以及大量结合紧密的两相界面能够有效地限制活性颗粒在脱锂过程中的体积收缩并促进电荷在活性颗粒内部的传输,促使该复合材料表现出优异的电化学性能。预脱锂和首次嵌锂比容量分别为968和1007mAh·g^(-1),达到商业化应用锂-碳体系的3倍,首次库伦效率达到94.5%。循环100圈后比容量仍然可保持在590mAh·g^(-1),循环稳定性相比于采用碳颗粒制备的复合材料提升了1倍。即使在1 A·g^(-1)的高电流密度下循环,比容量仍可保持在540 mAh·g^(-1)。本研究为设计开发应用于锂离子硫、锂离子氧等高能量密度电池体系中的富锂合金负极材料提供了新的途径。Taking advantage of simultaneous thermochemical lithiation and densification of spark plasma sintering, the Li21Si5/graphene nanocomposites with uniform distribution and high density were prepared. Due to the two-dimensional structure and excellent electrical conductivity of graphene, and the presence of a high proportion of tightly bonded in- terfaces of Li21Si5/graphene, the volume shrinkage of the active particles during the delithiation process was limited effectively, and the charge transport inside the active particles was enhanced dramatically. Therefore, the composite exhibits excellent electrochemical performance. The specific capacities of pre-delithiation and the first lithiation were 968 mAh·g^-1 and 1007 mAh·g^-1, respectively, which are 3 times as high as thoseof the commercial lithium-carbon compound. Its first Coulomb efficiency was 94.5% at the same time. Moreover, the specific capacity remained 590 mAh·g^-1 after 100 cycles, and the cyclic stability doubled compared to the composites prepared by carbon particles. Even at a high current density of 1 A·g^-1, the specific capacity can be maintained at 540 mAh·g^-1. This work pro- vides a new approach for the development of lithium-rich alloy anode materials, which are promising in high energy density batteries, such as lithium ion-sulfur and lithium ion-oxygen systems.

关 键 词：锂化 负极 石墨烯 复合材料 锂离子电池 

分 类 号：TQ152[化学工程—电化学工业]