多孔硅/铜复合负极材料的制备及其电化学性能

Abstract

多孔硅材料具有特殊的孔洞结构,可以缓解嵌脱锂过程中电极材料的体积效应,已成为锂离子电池负极材料的重点研究方向之一,但仍然存在导电性差等缺点.本文采用光助电化学腐蚀、二次化学腐蚀扩洞、脉冲电沉积铜三步法制备出多孔硅/铜基复合负极材料,通过优化腐蚀条件得到了高孔隙率的多孔硅,然后在孔洞内部及表面包覆导电性较好的铜颗粒层.电化学性能测试表明,该多孔硅/铜基复合负极材料电池在0.05C的恒流充放电循环测试下,首次充放电比容量分别为2 413和4 282MAH/g,比未沉积铜的多孔硅基电极增加了414和1 900MAH/g,且容量保持率也比未沉积铜的有所改善.

Porous silicon(PS)can accommodate large mechanical strains by providing the empty space of pores to alleviate the volume change during the charge and discharge progress of the lithium ion batteries(LIBs),making it a promising material for rechargeable LIBs.But the electronic conductivity of PS is relatively low.In view of this,Porous silicon/copper(PS/Cu)composite is synthesized as the LIB anode by a three-step approach:electrochemical etching with illumination,chemical etching,and electrodepositing of Cu.By optimizing the etching conditions,PS with high porosity is obtained.Subsequently,the PS is coated with Cu not only on the surface but also in pores of PS by electrodepositing of Cu,which has high electrical conductivity.Electrodes based on PS/Cu achieve an initial charge/discharge capacity of 2 413mAh/g and 4 282mAh/g,which are 414mAh/g and 1 900mAh/g higher than the PS based electrodes.The cycle performance is also more enhanced than PS based electrodes.