Welding method, welding apparatus, welding device, and battery cell

A welding method, comprising:

• placing a housing covered with an end cap into a jig, the jig including a receptacle for accommodating the housing covered with the end cap and a pressing plate located at an opening of the receptacle, such that, after the placing, the housing is inverted on the end cap with the end cap located at a bottom of the receptacle and the pressing plate pressed against the housing to push the housing toward the end cap so as to press and fix the end cap to the housing, wherein a clearance structure is formed as openings arranged on opposite sides of the jig and available for exposing a target weld zone between the end cap and the housing, and the target weld zone comprises a first target weld zone section and a second target weld zone section located on two opposite sides of the end cap respectively;
• and
• moving the jig to a first welding station of a welding device;
• welding, by a first welding head of the welding device, the first target weld zone section through the clearance structure;
• and welding, by a second welding head of the welding device, the second target weld zone section through the clearance structure, wherein the first welding station is located between the first welding head and the second welding head.