Nonprelithiated Full Cells With 100% Micro‐Silicon Anodes Enabled by Replacing Inner SEI Layer

Micro-sized silicon (Si) is a highly attractive anode for next-generation lithium-ion batteries (LIBs) because of its ultrahigh specific capacity and low cost, yet its practical application is severely limited by rapid capacity decay. In this study, we develop a functional molecule, (2S,2'S)-N,N'-carbonylbis(2-amino-2-hydroxyacetamide), to construct an in situ interfacial layer on porous micro-Si. This layer homogenizes the pore structure by covering most micropores, thereby enabling more uniform Li-ion insertion and alleviating the drastic phase transition of Si during lithiation. It also induces and contributes to the formation of a dense, thin, uniform, and LiF-rich solid electrolyte interphase (SEI) with excellent electronic insulation and ionic conductivity. As a result of this coupled structural and interfacial regulation, the Si anode shows a marked improvement in electrochemical performance, with the specific capacity at 10 C rises from 945 to 2041 mAh/g, and the capacity retention improves from 15.9% to 64.2% after 1000 cycles at 25°C. In full cells without prelithiation, the initial Coulombic efficiency (ICE) increases from 83.77% to 88.11%, specific capacity at 5 C increases from 17 mAh/g to 99 mAh/g, capacity retention rises from 11.5% to 71% after 100 cycles at 45°C, demonstrating the practical promise of 100% micro-Si anodes.