Improved lithium storage performance by encapsulating silicon in free-standing 3D network structure carbon-based composite membranes as flexible anodes

Carbon-encapsulation is an effective strategy to inhibit the volume expansion and enhance the cycle stability of silicon anode in the lithium-ion battery. However, it is still a big challenge to prepare carbon/silicon composite materials with excellent flexibility using a simple and high-efficient method. Herein, a flexible carbon-based composite membrane embedded with nano-silicon particles and graphene is successfully developed via simple precursor preparation and carbonization processes. The obtained carbon-based composite membrane possesses a porous 3D network structure, which can provide buffer space to alleviate the volume expansion of nano-silicon. Due to the unique architecture, the carbon-based composite membrane presents a high reversible capacity of 1135.7 mA h g−1 and an effective utilization rate of nano-silicon up to 92.6%. After 100 cycles, the reversible capacity is still maintained at 897.6 mA h g−1 with a capacity retention rate of 74.2%. Furthermore, after 100 cycles, almost no capacity loss is detected, and the Coulombic efficiency is close to 100%, demonstrating excellent reversibility and robust stability. In summary, this research provides a simple and high-efficiency strategy for the preparation of flexible carbon/silicon composite anodes for lithium-ion batteries.