Corrosion Behavior of Type 430 Stainless Steel in a Non-aqueous Electrolyte for Lithium-ion Batteries Containing LiPF₆ Salts

Abstract

Type 430 stainless steel showed different corrosion behavior from Type 304 in a non-aqueos electrolyte containing LiPF₆ in terms of potential dependency. At 4 V （Li/Li^＋）, Type 430 was highly susceptible to corrosion while Type 304 was resistant. At 5 V （Li/Li^＋）, Type 430 was passivated as well as Type 304. X-ray photoelectron spectroscopy （XPS） analysis revealed that Type 430 was protected by two-layer of passivation film at 5 V （Li/Li^＋）. The outer layer consited of Fe-fluoride （FeF₃） and smaller amount of oxide of Fe and Cr. It was suggested that FeF₃ played an essential role in the passivation of Type 430 at 5 V （Li/Li^＋）. The higher corrosion susceptiblity of Type 430 at 4 V （Li/Li^＋） was ascribed to the difficulty of forming of FeF₃, and the lower corrosion resistance of the pristine film as compared with Type 304.