Effective coating of polydopamine-mediated polyacrylamide on SiOx microparticles enables stable interface chemistry

Abstract

Functional polymer coating is one of effective strategies to achieve high performance Si-based anodes for lithium-ion batteries (LIBs). Unfortunately, many functional polymers are incompatible with carbon layer which are important for electrical conductivity of Si-based composites, especially for carbon-coated SiOx microparticles (SiOC). Here, we present a polydopamine (PDA)-mediated strategy that enables a robust polyacrylamide (PAM) polymer to effectively couple with SiOC microparticles through the PDA bridge. As a robust barrier, the PDA-PAM coating effectively inhibits electrolyte corrosion while promoting the formation of a stable solid electrolyte interface layer. The resulting SiOC@PDA-PAM microparticles display enhanced cycling stability without sacrificing their rate performance. The pouch cell incorporated with 10 wt% SiOC@PDA-PAM in graphite anode has a superior capacity retention of 85.1% after 800 cycles and an improved storage performance due to the stable interfacial chemistry of SiOC@PDA-PAM. Considering the strong adhesion and easy functionalization of PDA for surface modification, this work spotlights the prospect of developing more functional polymer coating to extend the cycling life of Si-based anodes.