Patent ID: 11870040

Abstract:
According to the present disclosure, a technique capable of suppressing an internal short circuit caused by a peeled metal piece and obtaining a safer secondary battery is provided. An electrode plate (negative electrode plate) disclosed herein includes a negative electrode core including copper or a copper alloy, a negative electrode active material layer applied to a surface of the negative electrode core, and a negative electrode tab protruding to the outside from one end side in a width direction. In the negative electrode plate, a first region having an oxide film having a thickness of 40 nm to 200 nm is formed in a region of 0.01 mm to 0.2 mm from an outer end side of the negative electrode tab toward the inside in the width direction, and the first region 22t1 extends along the outer end side 22ta of the negative electrode tab 22t. As a result, a metal piece that can be peeled off from the negative electrode tab 22t can be insulated and inactivated in advance, so that an internal short circuit due to the peeled metal piece can be suppressed.