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

4.5 V-class lithium-ion batteries (LIBs) pairing LiNi_0.8Mn_0.1Co_0.1O₂ (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.