A metal oxide coating to suppress the corrosion of aluminum current collectors for high-voltage LiTFSI-based batteries

Abstract

We propose a metal-oxide coating (MOC) strategy to enhance the anti-corrosion of Al current collectors in LiTFSI-based electrolytes, aiming to attain stable interfaces and excellent capacity retention of high-voltage batteries. The robust passivation oxide layer (e.g., V-/Mn-/Fe-(N) oxide coatings) is prepared on the Al surface, which dramatically lowers the corrosion rate of Al by nearly three orders of magnitude to 10⁻⁵ A cm⁻². The metal oxide coating is transformed into a protected layer made of a metal cation (M^m+) coordinated with TFSI⁻, thereby suppressing the dissolution of Al (Al³⁺) in aggressive LiTFSI-based electrolytes and then slowing down the degradation of electrode performance. Among multiple transition metal oxide coatings, the Fe-(N) oxide coating exhibits the best high-voltage tolerance of 5 V stability. The Fe-(N) oxide coating has the lowest LiTFSI defluorination conversion barrier and forms a composite passivation layer containing Fe–F, Al–N bonds, thus improving the interface stability. The results remind us that the synergy regulation of electrolyte optimization and electrode coating strategy might be ideal for designing anti-corrosion electrodes for next-generation high-voltage batteries.