SECONDARY BATTERY

The present application provides a secondary battery, including: an electrode assembly, a packing bag, an electrode lead and an insulation part; the electrode assembly is housed in the packing bag, the packing bag has a sealing part on an edge, and the electrode lead is connected to the electrode assembly and passes through the sealing part. The sealing part includes a main body area, a first step area and a first transition area; the main body area, the first transition area and the first step area are located on a same side of the electrode lead along a width direction, and the main body area, the first transition area and the first step area are successively arranged along a direction approaching the electrode lead; the insulation part is wrapped around outside of the electrode lead and separates the sealing part from the electrode lead; the insulation part has a first portion, and the first portion is located on a side of the electrode lead close to the main body area along the width direction; the first step area covers the first portion on both sides in a thickness direction. The present application improves the sealing performance of the secondary battery.