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

Abstract

ABSTRACT 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.