Breaking the Performance Bottleneck of Silicon Anodes with Ultrahigh Areal Capacity via Solid‐State Electrochemical Prelithiation

Abstract Silicon anodes hold great promise for next‐generation lithium‐ion batteries (LIBs), yet suffer from substantial first‐cycle irreversible capacity loss with low initial Coulombic efficiency (ICE) and large volumetric expansion during cycles. To resolve these challenges, a solid‐state electrochemical corrosion (SEC) prelithiation strategy is proposed for thick‐film Si anodes. These findings highlight the critical role of homogeneous Li + distribution in both liquid‐ and solid‐state batteries. The SEC prelithiation approach achieves an ICE of 94.13% in liquid‐state batteries while achieving a ≈90% reduction in Si dissolution. In solid‐state batteries, this method demonstrates remarkable interfacial stability, with the pressure variation (ΔP) at the delithiation state shifting from 0.19 to −2.0 MPa during initial cycling, accompanied by a 19.75% reduction in volumetric expansion after 200 cycles. Full cells pairing SEC‐prelithiated anodes (≈8 mAh cm −2 ) with LiNi 0.7 Mn 0.2 Co 0.1 O 2 cathodes can achieve high energy densities of 470.5 Wh kg −1 with 86.70% capacity retention after 135 cycles in liquid‐state cells, and 444.3 Wh kg −1 with 77.19% retention over 209 cycles in all‐solid‐state batteries, respectively. This work establishes a clear relationship between homogeneous Li + distribution and improved electrochemical stability, offering a transformative pathway to overcome the long‐standing limitations of Si anodes and advancing their commercial viability in high‐energy‐density LIBs.