Stress-dissipated conductive polymer binders for high-stability silicon anode in lithium-ion batteries

Abstract

Silicon-based anodes with high theoretical capacity have intriguing potential applications for high energy density lithium-ion batteries (LIBs), while suffer from immense volumetric change and brittle solid-state electrolyte interface that causes collapse of electrodes. Here, a stress-dissipated conductive polymer binder (polyaniline with citric acid, PC) is developed to enhance the mechanical electrochemical performance between Si nanoparticles (SiNPs) and binders. Benefiting from the stable triangle network node of citric acid and a considerable distributed of hydroxyl groups, the PC binder can effectively dissipate the stress from SiNPs, thus providing an excellent cyclic stability of Si anodes. Both experimental results and theoretical calculation demonstrate the enhanced adhesion between binders and SiNPs could bond the particles tightly to form a robust electrode. The as-fabricated Si anode exhibits outstanding structural stability upon long-term cycles that exhibit a highly reversible capability of 1 021 mA·h·g−1 over 500 cycles at a current density of 0.5 C (1 C = 4 200 mA·g−1). Evidently, this stress-dissipated binder design will provide a promising route to achieve long-life Si-based LIBs.

Keywords

• Conductive polymer
• Silicon anode
• Binder
• Mechanical electrochemistry
• Lithium-ion batteries