Fabrication of polypyrrole-coated silicon nanoparticle composite electrode for lithium-ion battery

Abstract

Silicon has been the most ideal candidate anode material for high-capacity lithium-ion batteries owing to its higher theoretical capacity, relatively low potential, and rich resources. Unfortunately, the significant volume expansion (300%) and low intrinsic conductivity result in poor electrochemical performance during the charging-discharging process. Herein, one-dimensional linear polypyrrole-coated silicon nanoparticle (Si@PPy) composites are synthesized to elevate the lithium storage performance of silicon-based materials. The Si nanoparticles are coated by polypyrrole to form a one-dimensional linear structure, which not only enhances the electron/ion transfer rate, but also relieves the volume changes of Si. Simultaneously, the constructed interwoven network would be beneficial for the electrolyte immersion and provide more space for the expansion of the entire electrode. So the Si@PPy-2 composites demonstrated superior electrochemical performance with a discharge capacity of 1660.2 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹ and the reversible specific capacity of 1047.0 mAh g⁻¹ at a high current density of 1000 mA g⁻¹ for 500 cycles. This simple in situ polymerization method to prepare high-performance Si anodes would be beneficial for the commercialization of silicon-based electrodes in LIBs.