Cell‐Membrane‐Inspired Conjugated Microporous Thermoset Interface for High‐Rate and Durable Silicon Anodes

Abstract

ABSTRACT Silicon (Si) is a promising anode material for next‐generation lithium‐ion batteries due to its ultrahigh theoretical capacity, abundance, and favorable operating potential. However, its widespread application is limited by severe volume expansion, sluggish lithium‐ion transport, and unstable solid electrolyte interphase (SEI). Inspired by the multifunctional architecture of biological cell membranes, we report a facile and scalable strategy to construct a bio‐inspired protective interface via in situ formation of a conjugated microporous thermoset (CMT) coating on Si particles. This process involves simple hand‐mixing of a molecular precursor with Si, followed by a one‐step thermosetting treatment featuring sequential sublimation, melting, debromination, and polymerization, without the need for post‐processing. The resulting CMT interface offers micropores (∼0.5 nm) for selective Li + transport while excluding electrolyte and anions, a covalently crosslinked yet resilient network to accommodate mechanical strain, and tailored interfacial chemistry that induces a LiBr‐rich SEI to enhance Li + transport kinetics. As a result, the engineered Si@CMT anode achieves a high capacity of 3130.9 mAh g −1 at 0.1 C, maintains 1811.8 mAh g −1 at 3 C, and delivers 1838.8 mAh g −1 after 250 cycles at 0.2 C. This practical and generalizable interfacial design offers a promising route toward scalable stabilization of high‐capacity anodes.