锂离子电池三维多孔硅/银复合材料负极设计及性能

Design and fabrication of silver-coated three-dimensional porous silicon composite anode with high performance for lithium ion battery

以商品单质硅为原料,利用金属辅助化学刻蚀方法结合化学镀方法制备了三维多孔硅/银复合负极材料,采用X射线粉末衍射仪、场发射扫描电镜及比表面与孔隙度分析仪对其组成、结构、比表面积及孔隙率进行研究,随后对其电化学性能进行研究.结果表明,三维多孔硅呈现狭缝型的介孔,平均孔径宽度为12.5 nm,比表面积达到6.083 m^(2)/g.三维多孔硅/银复合材料在420 mA/g条件下恒流充放电,首循环放电比容量2822 mA.h/g,首循环库仑效率87.8%,经过50个循环后容量仍保持有832 mA·h/g.研究表明:三维多孔结构和银包覆层可以缓解嵌锂/脱锂时硅巨大的体积效应;银包覆层可以改善硅基负极材料的电化学性能.

Silver-coated three-dimensional porous silicon(3 D-porous-Si/Ag)composites were fabricated as anode materials for a lithium-ion battery via a metal-assisted chemical etching(MACE)method and an electroless plating method.Commercial silicon powders were used as substrate material.The composition,microstructure,and specific surface area of 3 D-porous-Si and 3 D-porous-Si/Ag were analysed via X-ray diffraction,field emission scanning electron microscopy,and surface area and porosity analyses.The electrochemical performance of the 3 D-porous-Si/Ag composite was investigated.The results indicate that the aperture size and specific surface area of 3 D-porous-Si were 12.5 nm and 6.083 m^(2)/g,respectively.These pores can be attributed to the narrow slit mesopores.The chargedischarge plot under a constant current of 420 mA/g indicates an initial discharge capacity of 2822 mA-h/g for the 3 D-porous-Si/Ag electrode.The Coulombic efficiency reached87.8%after the first cycle,and the capacity of the 3 D-porous-Si/Ag electrode reached832 mA-h/g after 50 cycles.This is mainly because the 3 D-porous microstructure and silver coating effectively restrain the volume expansion of silicon caused by the insertion of lithium ions.Moreover,the silver coating improves the electrical performance of the Si material.