Discrete Microdomain-Bonded Binder Enables Mechanically Robust Micron-Silicon Anodes in Lithium-Ion Batteries.

Abstract

Micron-silicon (µSi) is a promising anode material for lithium-ion batteries (LIBs) due to its low production cost, high tap density, and exceptional theoretical specific capacity. However, its practical application is severely limited by over 300% volume expansion during cycling. Developing advanced functional binders is therefore crucial to overcoming this bottleneck, where nearly all strategies rely on constructing continuous internal bonding networks via polymers or in-situ crosslinked/polymerized binders. Herein, a novel bonding paradigm, discrete microdomain bonding (DMB), was proposed to tackle the huge volume expansion of µSi anodes. In this system, discretely distributed short-chain binder molecules enable precise anchoring of µSi particles at the microdomain level through interfacial hydrogen bonds. By exploiting microdomain-mediated dynamic adaptation mechanisms to accommodate substantial volume changes, µSi particles maintain excellent electrical contact throughout cycling, ensuring robust mechanical tolerance and extended lifespan. Consequently, µSi anodes integrated with the DMB binder exhibit a strikingly high initial coulombic efficiency (ICE) of 92.5% and a remarkable capacity of 2517.4 mAh g^-1 with 98.2% retention after 100 cycles at 0.5 A g^-1. This work establishes the DMB paradigm as an effective strategy for stabilizing high-capacity µSi anodes, providing a pathway for the development of durable and high-performance LIB technologies.