锡钴合金电沉积层的结构与锂离子嵌脱行为

应用电沉积方法制备Sn-Co合金镀层.X-射线衍射和扫描电子显微镜分析表明,该Sn-Co合金镀层为六方固溶体结构,含Co量为20%的Sn-Co合金,其沉积层呈现(110)择优取向.表面微孔随沉积层Co含量的增加而增多.以Sn-Co合金镀层作锂离子电极材料,电化学性能测试表明,其首次充电曲线表现出锡钴合金、锡及锡氧化物与锂合金化的多个反应综合特征,随后的充电曲线趋于稳定,呈现L i-Sn-Co合金化反应特征;具有择优取向和多孔结构的Sn-Co合金电极材料的充放电性能较好,首次库仑效率为63.9%,经过20次充放电循环后,其充电容量为461mAg/h,库仑效率为99%.

Structure and Properties of Electrodeposited Sn-Co Alloy Electrodes as Anode Material for Lithium-Ion Secondary Batteries

The Sn-Co alloy deposits were prepared by electroplating.The structure and electrochemical performance of the electroplated Sn-Co alloys have been investigated in detail.Experimental results show that the porous Sn-Co alloy film exhibits hexagonal solid solution,with Sn as the solvent, Co as the solute.The texture of the Sn-Co alloy coating exhibits(110) preferred orientation.Electrochemical tests show that the porous Sn-Co alloy coating electrodes can deliver a discharge capacity of 643mAh/g in the first cycle.At the 20~(h) cycle the charge was 461mAh/g.At initial charge curve the irreversible capacity is probably associated to a combination of processes,which may include the reduction of small amount of tin dioxide and cobalt oxide on electrode surface,solvent decomposition and the formation of a passivating film on the electrode surface.The porous Sn-Co alloy electrodes can partly accommodate the volume expansion and phase transition during cycling,and would improve the cycle life of the electrode.They are also beneficial to diffusion of Li into /out of macroporous materials,and improve dischargeability/chargeability at charge discharge cycle.