Mechanism of aluminum corrosion in LiFSI-based electrolyte at elevated temperatures

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 degrees 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.

Automated summary

The study found that in LiFSI-based electrolytes, the dissolution of Al(FSI)3 leads to the formation of irregular, loose, and unprotected AlF3 materials, intensifying aluminum corrosion. However, the use of LiBOB can effectively inhibit Al corrosion, forming a robust protective layer, promoting the transition from AlF3 to LiF, and further enhancing interfacial stability.