4.5‐V‐Class Safe Lithium‐Ion Batteries with Silicon‐Majority‐Graphite Anodes Enabled by Self‐Limiting Interphase

Abstract 4.5 V‐class lithium‐ion batteries (LIBs) pairing LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathodes with silicon‐majority graphite (SmG, >1500 mAh g −1 ) anodes can surpass 400 Wh kg −1 , but their cycling stability, safety, and low‐temperature operation are constrained by the difficulty in constructing stable interphase. This study reports a hybrid‐sulfonamide electrolyte (HSE) that can survive the aggressive chemistry of high‐voltage NMC811 and programs a self‐limiting inorganic interphase on Si by leveraging the electron‐limited onset at the Si||electrolyte junction. At first lithiation, the semiconductor characteristic and native SiO x create a space‐charge (depletion) region, so the anionic‐structure‐like sulfonamides bias first‐electron reduction, seeding lithium halide/chalcogenide inorganics that are electronically insulating yet Li + ‐permeable. The resulting thin, dense layer suppresses electron tunneling, dissolution, and resists crack‐induced stress concentration during Si expansion—thereby self‐limiting further growth. Consequently, NMC811||SmG coin cells with the HSE retain 80% capacity after 500 cycles at 4.5 V and ≈5 mAh cm −2 and operate over a wide range of temperature from −40 to 60 °C, markedly outperforming the carbonate electrolyte. 1.4 Ah pouch cells maintain 80.0% of initial capacity after 1150 cycles and exhibit thermal stability up to 300 °C. This work establishes self‐limiting interphase formation on Si as a practical electrolyte design target for high‐energy LIBs.