Tailored Hierarchical Silicon Microparticles with Copper/Carbon Layers for High Cycling Stability Lithium-Ion Storage

Three-dimensional porous Si withlarge particles offers a highmass and volume capacity. The low electrical conductivity of the material,however, remains a significant hurdle to overcome. In this work, nanoporousSiCu microparticles (np-SiCuMP) were synthesized by dealloying a SiCuAleutectic alloy. To enhance the cycling stability of Si microparticles,the carbon layer was coated on the surface of np-SiCuMP using thepyrolysis glucose method (np-SiCuMP@C). Highly conductive Cu providesfast electron/ion pathways, thereby overcoming the poor conductivityof Si microparticles. Moreover, the smaller Cu grains and carbon-coatinglayer as a support dispersed around Si enhance the cycling stabilityof Si microparticle electrodes, which prevents structural collapsecaused by volume shrinkage during lithium removal. Therefore, thedischarge specific capacity of np-SiCuMP@C is as high as 1114.3 mAhg(-1) with a capacity retention rate of 70% after200 cycles at 0.05 C, which is significantly better than that of np-Si70Cu30MP (54%). This novel CuSi composite dispersedin amorphous carbon presents a promising approach for the design ofSi particle anode materials.