A highly elastic and Li-ion conductive binder enables stable operation of silicon microparticle anodes in high-capacity and high-energy-density pouch cells

Abstract

The pulverization and disintegration of silicon microparticles (SiMPs) cause additional adherend failure, rendering the highly efficient binders for Si nanoparticle anodes ineffective for SiMP anodes. Herein, we report a grafted polar polymeric binder for constructing robust and durable adhesive joints in SiMPs, preventing the occurrence of the adherend failure. The grafted structure and rich polar groups within the proposed binder empower it with excellent interfacial adhesion and coverage capabilities, while strong intra/interchain interactions guarantee its high cohesive strength. These characteristics, in combination with high stretchability and elasticity, enable the binder to accommodate the substantial volume changes of SiMPs and maintain the firm coalescence of pulverized SiMPs without disintegration, resulting in a stable electrode–electrolyte interface and mechanical structure of SiMP anodes during cycling. Additionally, the high Li-ion conductivity of the proposed binder significantly reduces the hindrance to Li-ion transportation in SiMPs caused by binder coverage. Consequently, the SiMP anodes using the proposed binder exhibit impressive electrochemical performances with high initial coulombic efficiency and superior cycling stability. In particular, the SiMP anodes demonstrate stable and consistent cycling performances in high-capacity and high-energy-density pouch cells, highlighting the practical viability of the proposed binder.