Battery and manufacturing method of the same

A battery comprising an electrode group including a positive electrode, a separator, a negative electrode, and a protection layer,

• the separator being interposed between the positive electrode and the negative electrode,
• the positive electrode including a positive electrode current collector, a positive electrode mixture layer, and a positive electrode tab,
• the positive electrode mixture layer being disposed on a surface of the positive electrode current collector,
• the positive electrode tab being electrically connected to the positive electrode current collector,
• the protection layer covering a surface of the positive electrode tab,
• the protection layer including an insulation layer and a vapor-deposited metal layer,
• the insulation layer including an electrical insulating material,
• the vapor-deposited metal layer being interposed between the insulation layer and the separator,
• the vapor-deposited metal layer being in contact with at least a part of the positive electrode mixture layer.

A manufacturing method of a battery, the manufacturing method comprising:

• manufacturing an electrode group,
• the electrode group including a positive electrode, a separator, a negative electrode, and a protection layer,
• the separator being interposed between the positive electrode and the negative electrode,
• the positive electrode including a positive electrode current collector, a positive electrode mixture layer, and a positive electrode tab,
• the positive electrode mixture layer being disposed on a surface of the positive electrode current collector,
• the positive electrode tab being electrically connected to the positive electrode current collector,
• the protection layer covering a surface of the positive electrode tab;
• conducting a withstand voltage test on the electrode group,
• the withstand voltage test determining the electrode group to be a defective product when a leakage current flows between the positive electrode and the negative electrode by applying a voltage, lower than an insulation breakdown voltage of the separator, across the positive electrode and the negative electrode, under a condition that the leakage current flows through the protection layer when a foreign object is present between the protection layer and the negative electrode, and
• the withstand voltage test determining the electrode group to be a non-defective product when the leakage current do not flow between the positive electrode and the negative electrode by applying the voltage across the positive electrode and the negative electrode, under the condition;
• and
• manufacturing a battery including the electrode group that has been determined to be the non-defective product in the withstand voltage test.