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

Three-dimensional porous Si with large particles offers a high mass and volume capacity. The low electrical conductivity of the material, however, remains a significant hurdle to overcome. In this work, nanoporous SiCu microparticles (np-SiCuMP) were synthesized by dealloying a SiCuAl eutectic alloy. To enhance the cycling stability of Si microparticles, the carbon layer was coated on the surface of np-SiCuMP using the pyrolysis glucose method (np-SiCuMP@C). Highly conductive Cu provides fast electron/ion pathways, thereby overcoming the poor conductivity of Si microparticles. Moreover, the smaller Cu grains and carbon-coating layer as a support dispersed around Si enhance the cycling stability of Si microparticle electrodes, which prevents structural collapse caused by volume shrinkage during lithium removal. Therefore, the discharge specific capacity of np-SiCuMP@C is as high as 1114.3 mAh g–1 with a capacity retention rate of 70% after 200 cycles at 0.05 C, which is significantly better than that of np-Si70Cu30MP (54%). This novel CuSi composite dispersed in amorphous carbon presents a promising approach for the design of Si particle anode materials.