Passivation Failure of Al Current Collector in LiPF6‐Based Electrolytes for Lithium‐Ion Batteries

Abstract Next‐generation Li‐ion batteries are being developed with high‐voltage cathodes to maximize their energy and power densities. However, the commercialization of high‐voltage cathodes has been delayed due to the degradations of active materials and electrolytes in long‐term cycling. Recent advances have made significant improvements in these issues; however, the corrosion of Al current collector and its effects on battery performances have not been studied in detail despite its importance. In this study, the compositional and morphological evolutions of the passivation layer formed on Al are examined. The ion fluxes of Al 3+ and F − through the native oxide layer of Al play a critical role in the formation of the passivation film and the inhibition of further corrosion. However, the continuous diffusion of the ions during long‐term cycling at elevated temperature deteriorates the passivation ability of the film. An artificial diffusion barrier on the surface of Al effectively suppresses the ion fluxes to enhance the cyclability of LiNi 0.5 Mn 1.5 O 4 . This work contributes to improving the stability of the current collector at high voltages and serves as a benchmark for corrosion studies concerning advanced energy storage devices.