Suppression of aluminum current collector corrosion in ionic liquid containing electrolytes

Solutions of LiTFSI in organic solvents such as carbonates, do not display the ability to prevent the aluminum corrosion and for this reason cannot be conveniently used as electrolytes in LIBs. However, addition of PYR14TFSI to PC–LiTFSI strongly suppresses the aluminum corrosion process, both at 20 °C and 60 °C. At 60 °C, in a mixture PC–PYR14TFSI–LiTFSI containing 50% of IL, the charge involved in the corrosion process is one order of magnitude lower than that observed in PC–LiTFSI. The suppression of the corrosion process by PYR14TFSI might be related to the reduced solubility of Al(TFSI)3 in PYR14TFSI compared to PC. Al(TFSI)3 is formed on the Al surface in electrolytes containing LiTFSI, and the low solubility of this compound in PYR14TFSI contributes to the formation of a stable protective layer on the Al surface, which in turn reduces the corrosion process. Thanks to their ability to suppress the Al corrosion, PC–PYR14TFSI–LiTFSI mixtures can be conveniently used as electrolytes in LIBs, both at room temperature and 60 °C.