锂离子电池多孔硅/碳复合负极材料的研究

以商业化多晶硅粉为原料, 采用金属银催化剂诱导化学腐蚀的方法制得三维多孔硅材料。通过优化腐蚀条件, 得到孔径约为130 nm, 比表面为4.85 m²/g的多孔硅材料。将多孔硅和PAN溶液混合球磨并经高温烧结后在多孔硅表面包覆上一层致密的无定形碳膜, 从而制得多孔硅/碳复合材料作为锂离子电池的负极材料。3D多孔硅结构可以缓解电化学嵌/脱锂过程中材料的体积效应, 无定形碳膜层可有效改善复合材料的导电性能。电化学性能测试表明, 该多孔硅/碳复合负极材料电池在0.4 A/g的恒电流下, 首次放电容量3345 mAh/g, 首次循环库伦效率85.8%, 循环55次后容量仍保持有1645 mAh/g。并且在4 A/g的倍率下, 容量仍维持有1174 mAh/g。该方法原料成本低廉, 可规模化生产。

Investigation of Porous Silicon/Carbon Composite as Anodes for Lithium Ion Batteries

3D porous silicon was synthesized by metal-assisted chemical etching process using commercially available polycrystalline silicon powders. After chemical etching in optimized solution, 3D porous silicon structures with pore size of about 130 nm and specific surface area of about 4.85 m²/g was obtained. Subsequently, the 3D porous silicon powders treated with ball milling and heat carbonization processes were coated with amorphous carbon and utilized as the anode electrode material for lithium ion battery. The combination of the 3D porous structure and a carbon coating layer can accommodate large mechanical strains by providing the empty space of the pores to alleviate the volume change, and by increasing the electrical conductivity with the carbon layer. The electrodes achieve an initial charge capacity of 3345 mAh/g with coulombic efficiency of 85.8% as well as a high reversible capacity of 1645 mAh/g after 55 cycles at 0.4 A/g. And it is capable to retain a capacity of 1174 mAh/g even at 4 A/g. Thus, this work introduces a novel and easy potential industrial method for fabrication Si/C materials for high-performance lithium ion battery.