Novel porous Si–Cu3Si–Cu microsphere composites with excellent electrochemical lithium storage

Si based alloy anode materials with remarkably enhanced electrochemical lithium storage are crucial forthe next generation high-performance lithium-ion batteries (LIBs). Herein, novel porous Si–Cu3Si–Cu microsphere composites are prepared from commercially available low-cost SiAl alloy microsphere precursor by a facile chemical reduction/etching strategy. The formation mechanism and unique microstructure of the porous Si–Cu3Si–Cu microsphere composites are elucidated, based on the physical characterizations of different intermediates and final products as well as the precursor. The final product Si–Cu3Si–Cu composite shows a porous microsphere structure, with Cu/Cu3Si nanoparticles anchoring on the Si surface and embedding in the 3D porous silicon networks. This improves the electronic conductivity of the composite and enhances the structure stability of porous Si microspheres. The as-prepared porous Si–Cu3Si–Cu microsphere composite displays an excellent electrochemical lithium storage performance, with a reversible capacity of 1401.2 mAh g−1 after 200 cycles at a relatively high rate of 1 A g−1. Based on the unique microstructures and the electrochemical experimental results, the enhanced lithium storage performance of the porous Si–Cu3Si–Cu microsphere composites is clarified.