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

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Hydrofluoric acid (HF) generation from LiPF6 in carbonate electrolytes is a major failure mechanism in high-voltage lithium-ion batteries.
• This degradation impacts battery performance and longevity, particularly under demanding operating conditions.

Purpose of the Study:

• To develop a novel dual-functional additive for effective and persistent acid scavenging in high-voltage lithium-ion batteries.
• To investigate the synergistic mechanism of the additive in neutralizing HF and stabilizing the battery's cathode-electrolyte interphase.

Main Methods:

• Rational molecular design of 5-trimethylsilanylthiazole (5-SiTZ) with siloxane and thiazolyl functional groups.
• Evaluation of 5-SiTZ's acid scavenging capability (<1s for HF removal) and long-term stability (>200 days).
• Fabrication and testing of commercial graphite||NCM811 pouch cells with the additive, cycling at 4.6 V.

Main Results:

• 5-SiTZ demonstrated ultrafast (<1s) and persistent (>200 days) scavenging of hydrofluoric acid (HF).
• The additive promoted the formation of a robust, inorganic-rich cathode electrolyte interphase.
• Graphite||NCM811 pouch cells exhibited excellent capacity retention (92.1% after 700 cycles at 4.6 V).

Conclusions:

• Synergistic molecular design of multi-functional additives offers a practical approach to enhancing battery durability.
• 5-SiTZ effectively mitigates HF-induced degradation, leading to significantly improved cycle life in high-energy lithium-ion batteries.
• This strategy provides a pathway for developing more stable and reliable high-voltage battery systems.