Biomimetic surface design enables a resilient solid electrolyte interphase for high-performance anodes

Abstract

Surface coating presents an effective methodology for mitigating the detrimental effects of large volume changes inherent to high-capacity anode materials (e.g. Si, SiO_x). However, designs often prioritize the protection of internal active particles, inadvertently neglecting the intricate interplay between the coating layer and the external electrolyte which exhibits profound influences on the solid electrolyte interphases (SEIs). Inspired by the extracellular polymeric substance (EPS) protecting biological cells (e.g. yeast) from predation and chemical damages, we prepare a conducting polymer-based EPS system (CP-EPS) on a surface bilayer comprising soft carbon membranes and compact graphene walls, constructing the biomimetic cellular structure. The CP-EPS chemically interacts with electrolyte catalyzing the symbiosis of integrated LiF-enriched SEIs and physically provide sufficient resilience for SEIs. This resilient SEIs offer excellent reaction kinetics and roughness which protects the structural integrity of the particle and itself from pulverization and excessive SEI thickening. The prepared SiO_x anode delivers a superior average coulombic efficiency of 99.4 % over 200 cycles at 0.5C and a high reversible capacity of 730 mAh g^-1 after 300 cycles at 2C.