Mixed salts of LiTFSI and LiBOB for stable LiFePO4-based batteries at elevated temperatures

Abstract

To achieve excellent long-term cycling stability of LiFePO₄-based batteries at elevated temperatures, mixed salts of LiTFSI and LiBOB are used to replace the LiPF₆ salt in non-aqueous electrolytes. It is found that adding LiBOB into LiTFSI-based electrolytes effectively prevents severe corrosion to the Al current collector that is often observed in LiTFSI-based electrolytes which have high thermal stability. The LiFePO₄ cells using LiTFSI–LiBOB-based electrolytes demonstrate superior high temperature (60 °C) stability and similar room temperature performance (i.e., cycling stability and rate capability) when compared to the cells using the LiPF₆-based electrolyte.