Effect of fluoride additives on the corrosion of aluminum for lithium ion batteries

Effect of fluoride additives was investigated in organic solvents containing LiCF 3SO 3 to prevent the corrosion of aluminum current collector for lithium ion batteries. LiClO 4 was also examined for comparison. Among examined LiBF 4, LiPF 6, LiAsF 6, LiSbF 6 and LiClO 4, LiBF 4 was the best additive to suppress the corrosion of aluminum because its oxidation potential is close to that of CF 3SO − 3 anion. Corrosion currents for aluminum in a complex fluoride- or LiClO 4-added solvents became smaller in the order, LiSbF 6>LiAsF 6>LiClO 4>LiPF 6>LiBF 4. Oxidation potential of ClO − 4 is nearly the same as that of CF 3SO − 3. However, the corrosion currents were similar to or slightly larger than those observed in LiPF 6-added solvents. SEM images of electrochemically oxidized aluminum samples indicated that the level of corrosion well coincided with the observed corrosion currents. The corrosion mechanism of aluminum was also proposed. Graphic