Lithium difluoro(oxalato)borate as an additive to suppress the aluminum corrosion in lithium bis(fluorosulfony)imide-based nonaqueous carbonate electrolyte

摘要

Lithium bis(fluorosulfony)imide (LiFSI) is a promising alternative lithium salt to replace lithium hexafluorophosphate (LiPF6) due to its high conductivity and excellent compatibility with electrode material. On the other hand, the aluminum corrosion caused by LiFSI hinders its application in lithium ion battery. To solve this problem, lithium difluoro(oxalato) borate (LiDFOB) is added to suppress the aluminum corrosion in LiFSI-based nonaqueous carbonate electrolyte. The electrochemical tests in three-electrode cells and graphite/LiCoO2 full cells confirm that the addition of LiDFOB is beneficial to suppress the aluminum corrosion. In addition, the mechanism is proposed that the oxidation products of LiDFOB form a passivating film at the aluminum surface to suppress the corrosion based on the experimental results from SEM and XPS tests.