Porous carbon-coated silicon composites for high performance lithium-ion batterie anode

Abstract

With the rapid development of silicon-based lithium-ion battery anode, the commercialization process highlights the importance of low-cost and short-flowproduction processes. The porous carbon/silicon composites (C/Si) are prepared by one-step calcination using zinc citrate and nano-silicon as the primary raw materials at a temperature of 950 °C. In this composite, silicon nanoparticles are coated with a porous carbon shell with an average pore diameter of 4.49 nm, which improves the structural stability and electrochemical performance of the anode. Density-functional theory calculations show that the porous carbon enhances the electrical conductivity, facilitates the interlayer migration of Li-ion, and strengthens the gain effect of stress on conductivity. Additionally, stress further reduces the diffusion barriers of Li-ion. The porous C/Si anode demonstrates outstanding specific capacity and rate capability, maintaining a stable specific capacity of 1170 mAh/g at a current density of 0.2 A g−1 after 100 cycles and retaining a reversible specific capacity of 944 mAh/g even at a charging current density of 2 A g−1. The carbon/silicon anode materials prepared using this strategy present a streamlined manufacturing process and exceptional performance, as well as avoiding the post-washing step, providing a pathway toward the scalable application of silicon-based anodes.