Microporous Binder for the Silicon-Based Lithium-Ion Battery Anode with Exceptional Rate Capability and Improved Cyclic Performance

Abstract

Silicon anodes with high theoretical capacity have intriguing potential applications for next-generation high-energy lithium-ion batteries. However, silicon anodes suffer from an enormous volumetric change that causes pulverization of electrodes. Utilization of high performance binder is one of the most promising ways to improve electrochemical performance of the silicon-based anode. In this work, a polymer of intrinsic microporosity (PIM) is synthesized and used as binder for the silicon anode, which is composed of rigid polymer backbone, intrinsic porous structure, and active carboxyl groups (PIM-COOH). Compared to the conventional binders, both the cyclic performance and rate capability of the PIM-COOH/silicon electrode are significantly improved. The mechanism responsible for the enhanced performance is investigated. The PIM-COOH binder provides stronger adhesion towards the current collector than the conventional binders. Unique rigid polymer backbone and porous structure of PIM-COOH binder enable a good capability to withstand the volume expansion and mechanical stress generated by the cycling process. The porous structure and high specific surface area enhance lithium-ion transportation compared to other binders, which improves rate performance of the silicon based anode. This work provides a unique insight about design, synthesis, utilization, and mechanism of the porous binders to improve both cyclic and rate performance of the silicon based lithium-ion battery anodes.