硅基三元合金的非晶化制备及其储锂性能调控

硅基合金材料是下一代高性能锂离子电池理想的负极材料之一，要提高其应用前景的关键在于提高循环过程中的容量保持率，其本质是提高其嵌锂/脱锂前后的结构稳定性。本项目针对硅基合金负极材料嵌锂/脱锂过程中的相演变导致结构循环稳定差的基础科学问题进行研究，通过机械合金化法制备非晶态硅基三元合金材料，设计并优化其成分与非晶结构；研究合金材料中活性/非活性成分的相互作用对电极结构稳定性、容量释放以及嵌-脱锂动力学的影响规律，并建立相关的数学模型，为调控合金材料的储锂性能提供科学依据；揭示非晶硅基三元合金的储锂机制，抑制嵌锂过程中破坏结构稳定性的Li15Si4的晶化行为，逆向作用于合金材料的结构和性能优化。本项目研究对于实现硅基合金负极材料的高容量和优异循环稳定性的统一可以提供科学的理论指导意义，提高开发出高性能锂离子电池硅基材料的应用前景。

Si-based alloy has been considered as one of the most promising anode for next-generation lithium ion battery. The most challenge to improve its potential application is to enhance capacity retention during cycling, which depends on volume change reversibility induced by alloying/dealloying with lithium. This project focuses on the basic problem related to the poor structural stability induced by phase transformations of Si-based alloys during lithiation and delithiation. Amorphous Si-based ternary alloy containing unstable compounds will be prepared by mechanical alloying. Firstly, composition and amorphous microstucture of Si-based alloys will be designed and optimized. Secondly, the relationship between compositions, stuctural stability and lithiation storage performance, including capacity release, capacity retention and lithium diffusion knetics, will be investigated. Thirdly, lithiation-delithaiation mechanism of amorphous Si-based ternary alloys will be also revealed, as well as crystallization of Li15Si4 during lithiation will be inhibited, which should enhance structural stability of electrodes. The above studies will give a theoretical guide to realizing a good balance between high capacity and excellent cycleability in Si-based alloy anodes, and also increase potential application to develop high-performance Si-based anodes for lithium ion battery.