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

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.