Anion coordination strength mediated aluminum corrosion for high-voltage lithium-metal batteries

While high-voltage lithium-metal batteries are severely hindered limitations of active materials and electrolytes, the corrosion of aluminum (Al) current collector attract mild attention. In this work, the Al corrosion behavior mediated by anion is probed from the electrolyte solvation chemistry. The strong coordination strength of difluoro (oxalato)borate (DFOB⁻) anion effectively binds with Al³⁺, forming the contact ion pairs and aggregates structures. Compare with solvent-separated ion pairs, these structures with Al³⁺ complex deposit more readily on Al surface, exhibiting excellent capability to inhibit Al corrosion. The performance of Li||NCM622 cells employing lithium salts that inhibit Al corrosion is improved. This result confirms the detrimental impact of Al corrosion on battery performance under high-voltage cell operation, contributing to a deeper understanding of that the strong coordination strength anion inhibits Al corrosion and provides valuable insights for designing electrolytes for high-voltage batteries.