STEEL MATERIAL FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY CASE

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive steel material free from corrosion of a case and degradation of battery performance associated with metal elution even when a potential rise of a case occurs in a metal outer package case of negative electrode connection or neutral.SOLUTION: The steel material is provided with a Cr plating layer on the surface having an oxide film whose thickness is 10 to 500 nm on the surface. Preferably, an oxide film contains an element selected from Al and P. Preferably also, a Ni plating layer is provided under the Cr plating layer. Preferably, the oxide film is formed by anode electrolysis processing.