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

Hydrofluoric acid (HF) generation in carbonate-based electrolytes with LiPF₆ 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 PF₅ 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.