Control of LiFePO4 air-aging through the use of electrolyte additive

• Diethylamino trimethylsilane scavenges acidic impurities, surface structural OH or HF.
• Dissolution of LiFePO4 in LiPF6 electrolyte is successfully contained.
• Outstanding electrochemical performance is obtained from severely air-aged materials.
• MAS NMR shows that the interphasial chemistry is governed by the additive.

Air-aged LiFePO4 exhibits an OH-rich surface that reacts with LiPF6 based electrolyte, leading to poor battery performance. We show that outstanding electrochemical performance is achieved when using air-aged LiFePO4 in the presence of electrolyte additive N,N-diethylamino trimethylsilane, capable of reacting with acidic impurities. Stable impedance is obtained upon cycling, and 7Li and 19F MAS NMR study indicates that the interphasial chemistry is governed by a surface layer coming from reacted additive.