Anodic behavior of aluminum in organic solutions with different electrolytic salts for lithium ion batteries

The anodic polarization behavior of aluminum (Al) as a current collector of lithium (Li) ion battery has been investigated in organic electrolyte solutions containing different lithium salts. The Al current collector has suffered serious corrosion in the solution containing Li(CF₃SO₃)₂N (LiTFSI) under an anodic polarization condition, whereas, it was anodically stable in the LiPF₆ solution. In the solution of Li(C₂F₅SO₂)₂N (LiBETI), the Al anode showed an intermediate character between those in the LiPF₆ and LiTFSI solutions. The corrosion behavior of the Al electrode was much influenced by its surface condition. The addition of LiPF₆ in the imide-salts (LiTFSI and LiBETI) solutions suppressed the anodic corrosion of Al. The results of electrochemical quartz crystal microbalance (EQCM) experiments proved that the anodic processes on Al in the organic electrolytes consist of the formation of surface films and their dissolution. The X-ray photoelectron spectroscopy (XPS) analysis suggests that the anodic stability of the Al electrode in the imide-salts solutions containing LiPF₆ is associated with the formation of a fluoride (AlF₃)-rich film on the Al surface.