METHOD OF FORMING PROTECTIVE LAYER ON ALUMINUM FOIL, COLLECTOR FOR LITHIUM ION SECONDARY BATTERY, AND LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a method of forming a protective layer on an aluminum foil in which the thicker protective layer is formed on the aluminum foil, a collector for lithium ion secondary battery having the protective layer formed in the method of forming the protective layer, and a lithium ion secondary battery.SOLUTION: A method of forming a protective layer on an aluminum foil includes: a heat treatment process of obtaining a heat-treated aluminum foil by carrying out heat treatment for holding the aluminum foil at 80 to 160°C for one hour or longer; a protective layer forming composition adjustment process of adjusting a protective layer forming composition by dispersing polytetrafluoroethylene (PTFE) and conductive particles in water; and a protective layer formation process of forming a protective layer on a top surface of the heat-treated aluminum foil by applying and drying the protective layer forming composition on the top surface of the heat-treated aluminum foil, the content ratio of the polytetrafluoroethylene (PTFE) being 0.5 to less than 7 mass% of the conductive particles in the protective layer forming composition adjustment process.