Mechanism of aluminum corrosion in LiFSI-based electrolyte at elevated temperatures
(1. College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, China;
2. CAS Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lake, Chinese Academy of Sciences, Xining 810008, China)
2. CAS Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lake, Chinese Academy of Sciences, Xining 810008, China)
Abstract: Lithium bis(fluorosulfonyl)imide (LiFSI) is a promising replacement for lithium hexafluorosphate due to its excellent properties. A solution to the corrosion of aluminum (Al) current collectors by LiFSI at elevated temperatures is essential. The mechanisms of Al corrosion in LiFSI-based electrolyte at 45 °C were studied with density functional theory calculations and spectroscopic investigations. It is found that the irregular, loose and unprotected AlF3 materials caused by the dissolution of co-generated Al(FSI)3 can exacerbate Al corrosion with the increase of temperature. Lithium bis(oxalate)borate (LiBOB) can effectively inhibit the Al corrosion with a robust and protective interphase; this can be attributed to the interfacial interactions between the Al foil and electrolyte. Boron-containing compounds promote the change from AlF3 to LiF, which further reinforces interfacial stability. This work allows the design of an interface to Al foil using LiFSI salt in lithium-ion batteries.
Key words: lithium-ion batteries; LiFSI-based electrolyte; lithium bis(oxalate)borate (LiBOB); corrosion inhibition; elevated temperatures; interfacial film