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

Abstract

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