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.