Inhibition of anodic corrosion of aluminum cathode current collector on recharging in lithium imide electrolytes

摘要

Pitting corrosion of aluminum as cathode current collector for lithium rechargeable batteries was found to take place at potential positive of 3.5 V in 1 mol dm{sup}(-3) LiN(SO{sub}2CF{sub}3){sub}2/EC + DME (1:1) electrolyte. The corrosion mechanism of aluminum in the presence of LiN(SO{sub}2CF{sub}3){sub}2 was proposed, and three methods were deduced to inhibit the aluminum corrosion based on this mechanism. As a result, an additive of lithium salts based on perfluorinated inorganic anions, especially LiPF{sub}6, was found to inhibit the aluminum corrosion to a certain extent by forming a protective film on aluminum surface. The oxidation stability of aluminum in LiN(SO{sub}2CF{sub}3){sub}2-containing electrolytes depended strongly on the solvent structure. The ether solvents such as tetrahydrofuran (THF) and dimethoxyethane (DME) were effective in preventing aluminum corrosion due to their low dielectric constants. Furthermore, LiN(SO{sub}2C{sub}2F{sub}5){sub}2 salt with a larger anion than that of LiN(SO{sub}2CF{sub}3){sub}2 was evaluated and good oxidation stability of aluminum was obtained regardless of the kind of solvents.