Targeted Multifunctional Fluorine‐Rich Copolymer Coating Design for Ambient‐Stable Prelithiated SiOC Anodes

ABSTRACT

Prelithiation is a pivotal strategy for enhancing the initial coulombic efficiency (ICE) and energy density of lithium‐ion batteries, yet its practical application is impeded by the pronounciked sensitivity of prelithiated electrodes to ambient moisture and oxygen during storage. Herein, we rationally devise a targeted design for a fluorine‐rich acrylate copolymer—poly (tridecafluorooctyl methacrylate‐co‐methyl methacrylate) (PFMMA)—and introduce it as a multifunctional protective coating, with Li ₁₃ Si ₄ ‐prelithiated SiOC electrodes (preSiOC) employed as a proof of concept. Fluorinated side chains impart strong hydrophobicity, while methyl methacrylate units retain electrolyte affinity; the two moieties act synergistically to stabilize electrodes in air and preserve unimpeded interfacial ion/charge transport during redox reactions. Consequently, the preSiOC/PFMMA electrode with a 540 nm‐thick PFMMA coating retains 97.4% capacity and 95.3% ICE after 48 h air exposure at 50% relative humidity (RH), alongside robust cycling stability (677.5 mAh·g ⁻¹ after 100 cycles). These results outperform both unprotected preSiOC and other reported conventionally protected prelithiated electrodes. Furthermore, the electrode shows exceptional environmental adaptability, maintaining functionality under extreme scenarios (10% RH for 100 days or 90% RH for 3 days). This study establishes a rational copolymer design paradigm for fabricating durable, electrolyte‐compatible interfaces, thereby accelerating the development of ambient‐stable prelithiated electrodes.