锂离子电池核型G@Cu0.85Sn0.15@C负极材料的改性

针对锡负极材料充放电过程中的体积效应，本文综合采用组分改性与结构改性的研究方法，合成Sn-Cu合金负极材料，研究Cu的掺入对Sn电化学稳定性的影响，同时基于优化改性的Sn-Cu合金开展核壳结构设计，研究最佳核壳结构构造工艺。结果表明，掺入Cu能在一定程度上改善Sn的循环稳定性，Sn-Cu样品的容量在60周循环后趋于稳定，库伦效率较高；核壳结构处理能大幅提升Sn-Cu合金负极材料的循环稳定性，采用球形改性天然石墨(d50=15μm)作为内核的样品首次放电比容量接近800mAh/g，充电比容量最大值超过了500mAh/g，100周容量保持率大于85%，最佳的核壳结构构造工艺是使用片状石墨作为内核，内核粒径为d50=15μm，外壳厚度为柠檬酸裂解碳占复合材料质量比的20%。核壳结构能将Sn-Cu合金的体积效应控制在“囚笼”式结构内，利于材料容量的发挥及循环稳定性的提升。核壳结构的可控制备对实现锡基合金负极材料的产业化具有重要的作用。

Component and Structure modification of Sn-base anode materials for Lithium ion batteries

In this paper, with the method of component and structure modifications, Sn-Cu alloy anode material was synthesized, and the preparation technology of the core-shell structure was studied, to solve the volume expansion during the charge and discharge process of Sn-based anode materials. The results showed that, the addition of Cu could improve the cyclic stability. The specific capacity of the Sn-Cu sample became stable after the 60th cycles, with high coulomb efficiency. And the core-shell structure could dramatically improve the cyclic stability of the Sn-Cu alloy. For the sample whose core was modificated natural spherical graphite(d50=15μm), the initial specific discharge capacity was nearly 800mAh/g, the max charge specific capacity was higher than 500mAh/g, and the capacity retention of 100 cycles was higher than 85%.The best preparation technology of the core-shell structure was that, flake graphite whose particle size was d50=15μm as core, the thickness of the shell was 20%(wt). The volume expansion can be contorlled within the “cage structure” by the core-shell structure, which benefits for the capacity performance and the improvement of the cyclic stability. The controllable preparation of the core-shell structure is important for the commercialization of Sn-based anode materials.