凝胶限域热还原衍生高熵Si–M–C负极材料及其储锂机制

硅基材料具有比容量高、工作电位适中和资源丰富等优点，采用硅基负极材料替代商业化碳材料是构建下一代高能量密度锂离子电池的关键技术之一。但是，该类材料存在体积形变大、固体电解质界面膜厚且不稳定和反应动力学缓慢的三大本征问题，严重制约了硅基材料的实际应用。针对上述问题，本项目提出以“硅胶/氰胶”互穿网络凝胶为前驱体、通过限域热还原路线制备高熵Si–M–C材料，作为锂离子电池负极材料的新思路。利用多种活性/惰性金属和碳组分共同克服硅的本征问题，同时利用高熵效应最大程度发挥多组分功能并赋予熵增益储能机制，协同提升Si–M–C材料的循环寿命、库仑效率和倍率性能。在此基础上，研究并揭示高熵Si–M–C材料的“组成/构型熵–储锂性能/机制”复杂构效关系，通过组成与构型熵设计进一步调控并优化其储锂性能，进而获得综合性能优异的实用化硅基负极材料。

Silicon-based materials possess high specific capacities, proper working potentials, and natural abundance, and replacing commercial carbon materials by silicon-based anodes has been one of the key techniques to build next-generation Li-ion batteries with high energy densities. Unfortunately, there are three intrinsic challenges including tremendous volume variation, thick and unstable solid electrolyte interphase film, and sluggish reaction kinetics, which severely restrict the practical implementation of silicon-based materials. To overcome these challenges, in this project we propose a confined thermal reduction route toward high-entropy Si–M–C anodes for lithium storage, using interpenetrating network gels of SiO2 gels and cyanogels as precursors. Multiple active/inactive metals and carbon components are vital to overcome the intrinsic challenges of silicon, and meanwhile, high-entropy effects are beneficial for fully realizing the functions of multi components and endowing entropy-gain energy-storage mechanisms, co-improving the cycling life, Coulombic efficiencies, and rate capability of Si–M–C anodes. Moreover, the complex relationships between composition/configurational entropy and Li-storage performance/mechanism of high-entropy Si–M–C anodes will be examined and uncovered. Furthermore, the Li-storage performance of high-entropy Si–M–C anodes will be modified and optimized through their composition and configurational entropy design, with the purpose of obtaining practical silicon-based anodes with excellent overall performance.