Corrosion Suppression of Aluminum Metal by Optimizing Lithium Salt Concentration in Solid-State Imide Salt-Based Polymer Plastic Crystal Electrolyte Membrane

Imide salt–polymer plastic crystal electrolytes (PPCEs) have been demonstrated to be very promising solid-state electrolytes for ambient lithium ion batteries (LIBs). However, anodic Al dissolution at high voltage, due to these salts, cannot form an AlF3/LiF passivation film (like LiPF6) on an Al surface, which limits their application in high-voltage solid-state LIBs. In this work two ambient workable PPCEs with different lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) concentrations are designed to investigate anodic Al dissolution suppression in solid-state imide salt-based electrolytes. The anodic Al dissolution is examined by a scanning electron microscope (SEM) and an energy dispersive spectrometer (EDS). The electrochemical performance is evaluated by solid-state LiCoO2/PPCE/Li4Ti5O12 cells. The results demonstrate that anodic Al dissolution is efficiently suppressed and the cell electrochemical performance is greatly elevated by optimizing LiTFSI concentration in PPCEs. The suppression mechanism of Al corrosion in concentrated PPCE is analyzed and suggested.