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.

Automated summary

In this work, nanoporous SiCu microparticles (np-SiCuMP) were synthesized and a carbon layer was coated on its surface (np-SiCuMP@C) to enhance the cycling stability of Si microparticles. The highly conductive Cu and carbon coating layer improved the conductivity and cycling stability of the Si microparticle electrodes. The discharge specific capacity of np-SiCuMP@C reached 1114.3 mAhg(-1) with a capacity retention rate of 70% after 200 cycles at 0.05 C, which was significantly better than np-Si70Cu30MP (54%).