Ultrafast and Persistent Electrolyte Acid Scavenger for Stable High‐Voltage Lithium Batteries

ABSTRACT Hydrofluoric acid (HF) generation in carbonate‐based electrolytes with LiPF 6 is a primary failure cause in high‐voltage lithium‐ion batteries. Here, a new dual‐functional additive 5‐trimethylsilanylthiazole (5‐SiTZ) is developed by rational molecular design for ultrafast and persistent acid scavenging. Siloxane group in 5‐SiTZ reacts spontaneously with HF, while its thiazolyl moiety acts as a secondary Lewis base scavenger and chelates PF 5 to suppress further HF generation. This synergistic action achieves ultrafast (<1 s) and complete HF removal for over 200 days upon open‐air exposure. Furthermore, 5‐SiTZ promotes the formation of a robust, inorganic‐rich cathode electrolyte interphase. The combined effect of persistent HF removal and interface stabilization enables commercial graphite||NCM811 pouch cells to deliver outstanding capacity retention of 92.1% after 700 cycles at 4.6 V. This work establishes a paradigm of synergistic molecular design for multi‐functional additives, providing a practical route to durable high‐energy batteries.