Carbon coated porous silicon flakes with high initial Coulombic efficiency and long cycling stability for lithium ion batteries

Silicon (Si) has been regarded as a promising next-generation anode material to replace carbon-based materials for Lithium ion batteries (LIBs). However, low initial coulombic efficiency and poor cycling stability limited its wide application. With this in mind, carbon coating porous Si nanosheets (pSi@C) were prepared through pyrolysis of C2H2 on porous Si nanosheets from air-oxidation demagnesiation of Mg2Si. Carbon coating improved electrical conductivity of the composite, which is beneficial to the diffusion of Li+ and maintain structural integrity. The obtained pSi@C electrode shows a high initial Coulombic efficiency of 80.3% and reversible capacities of 2510 mAh g-1 at 0.4 A g-1. Furthermore, even at a current density 2 A g-1, it can still show a reversible specific capacity of 1215 mAh g-1 after 200 cycles