| abstract |
PROBLEM TO BE SOLVED: To provide a secondary battery capable of preventing breakage due to electrode deterioration and improving charge / discharge cycle characteristics when an alloy material is used as a negative electrode active material. SOLUTION: A strip-like positive electrode 21 and a negative electrode are wound through a separator. The positive electrode current collector 21A has an elongation rate of 3% or more until breakage in the winding direction after being charged once or more. By repeating the expansion and contraction of the negative electrode active material, the cathode 21 is prevented from being deteriorated or broken during the charge / discharge cycle, and the cycle characteristics are improved. Specifically, the positive electrode current collector 21A is composed of at least one member selected from the group consisting of JIS aluminum alloys 1085, 1070, 1050, 1N30, 1100, 3003, 3004, 8021, and 8079, and is classified by type O. Preferably there is. [Selection] Figure 2 |