锂离子电池Si@G负极材料的制备及性能研究

Preparation and properties of Si@G anode materials for lithium ion batteries

采用化学气相沉积法,制备了石墨烯厚度可控的硅@石墨烯核壳结构复合材料。通过X射线衍射、扫描电镜、透射电镜和恒电流充放电等表征,研究了石墨烯厚度对复合材料形貌、结构以及电化学性能的影响。研究结果表明:更厚的石墨烯壳层,虽然会降低复合材料的比容量和首次库仑效率,但是可以显著提高电化学稳定性。当石墨烯壳层约为12 nm厚时,40次循环后充电比容量达到1 069.8 mAh/g,循环保持率为81.2%,而纯Si样品仅为23.5%。这归因于石墨烯对硅体积效应的缓冲及其优异的导电性能。

A silicon/graphene core-shell composite with controllable graphene thickness was prepared by chemical vapor deposition.The effects of graphene thickness on the morphology,structure and electrochemical properties of the composites were investigated by X-ray diffraction,scanning electron microscopy,transmission electron microscopy and constant current charge and discharge.The results show that the thicker the graphene shell,the lower the specific capacity and coulombic efficiency of the composite,but it can significantly improve the electrochemical stability of the composite.When the graphene shell is about 12 nm thick,the charge capacity reaches 1069.8 mAh/g after 40 cycles,and the cycle retention rate reaches 81.2%,and the pure Si material is only 23.5%.This is attributed to the buffering of graphene to silicon volume effects and its excellent electrical conductivity.