A battery, comprising: an electrode tab assembly, comprising: an electrode tab, and a protective layer arranged on the electrode tab and comprising a first connecting layer being an outermost layer of the protective layer; a package film comprising multiple layers of which one is a second connecting layer arranged on a surface of the first connecting layer, characterized in that, after the electrode tab assembly is packaged, a first step and a second step are formed on an outer surface of the package film; and the first step and the second step have a first thickness h and a second thickness j in a first direction of the battery respectively, and the second step is formed on both sides of the first step along a second direction of the battery, wherein the first direction is in the thickness direction of the battery and the second direction is in the width direction of the battery, and the first thickness h and the second thickness j respectively satisfying the following formulas: 2 t + p − 2c + 2 a × 95 % < h < 2t + p − 2c + 2a × 5 %; 2t + p − b − 2c + 2 a × 95 % < j < 2t + p − b − 2c + 2 a × 5 %; h > j; wherein t is a thickness of the package film, a is a thickness of the second connecting layer, p is a thickness of the electrode tab assembly, c is a thickness of the first connecting layer, and b is a thickness of the electrode tab; and the first thickness h and the second thickness j both comprising a thickness of the first connecting layer and a thickness of the second connecting layer in the first direction of the battery. an electrode tab assembly, comprising: an electrode tab, and a protective layer arranged on the electrode tab and comprising a first connecting layer being an outermost layer of the protective layer; an electrode tab, and a protective layer arranged on the electrode tab and comprising a first connecting layer being an outermost layer of the protective layer; a package film comprising multiple layers of which one is a second connecting layer arranged on a surface of the first connecting layer, characterized in that, after the electrode tab assembly is packaged, a first step and a second step are formed on an outer surface of the package film; and the first step and the second step have a first thickness h and a second thickness j in a first direction of the battery respectively, and the second step is formed on both sides of the first step along a second direction of the battery, wherein the first direction is in the thickness direction of the battery and the second direction is in the width direction of the battery, and the first thickness h and the second thickness j respectively satisfying the following formulas: 2 t + p − 2c + 2 a × 95 % < h < 2t + p − 2c + 2a × 5 %; 2t + p − b − 2c + 2 a × 95 % < j < 2t + p − b − 2c + 2 a × 5 %; h > j; wherein t is a thickness of the package film, a is a thickness of the second connecting layer, p is a thickness of the electrode tab assembly, c is a thickness of the first connecting layer, and b is a thickness of the electrode tab; and the first thickness h and the second thickness j both comprising a thickness of the first connecting layer and a thickness of the second connecting layer in the first direction of the battery.