Prelithiation Strategy for Silicon/Carbon Anodes Using AMPS‐Mediated SEI Stabilization

Abstract Silicon‐carbon (Si/C) materials are promising anode candidates for next‐generation lithium‐ion batteries due to their high theoretical specific capacity and excellent cycling stability. However, Si/C anodes suffer from severe irreversible capacity loss during the first charge‐discharge cycle, stemming from silicon's extreme volumetric expansion (up to 300%) during lithiation, which triggers repeated rupture and reformation of the solid electrolyte interphase (SEI) film, depleting active lithium reserves. To address this, pre‐lithiation is implemented by pressing lithium strips onto the Si/C anode surface to compensate for active lithium and enhance initial Coulombic efficiency. However, overcompensation can cause capacity loss and safety risks. Thus, 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) is introduced as an auxiliary material. AMPS promotes stable SEI formation, reduces its repeated rupture, and consumes excess active lithium during pre‐lithiation. Experimental results show that the AMPS‐treated pre‐lithiated Si/C anode achieves an initial Coulombic efficiency of 91.24% (up from 77.47%) and maintains 83.8% capacity retention after 180 cycles. These findings highlight AMPS's role in improving pre‐lithiation effects and enhancing the electrochemical performance of Si/C anodes.