A method for forming a material-locking connection between a first element formed of copper with a thickness of less than or equal to 70 micrometers with a second element formed of copper or aluminum and a thickness of greater than or equal to 800 micrometers by means of resistance welding, wherein, to form the material-locking connection between a first electrode, in particular a positive electrode, and a second electrode, in particular a negative electrode, an electrical current flows, such that the first element and the second element are connected in a material-locking fashion in a connection area, while a force is applied on the connection area at least with a contact area of the first electrode wherein the contact area of the first electrode is rounded.

A welding gun is incorporated into a unidirectional welding system, where the unidirectional welding system includes: the welding gun performing welding when a set pressing force is applied; a power portion configured to generate power to be applied to the welding gun; a power connecting portion having one end portion connected to the power portion through a power wire and an opposite end portion engaged with the welding gun; and a power switch provided at the power connecting portion to selectively apply the power generated from the power portion to the welding gun.

A welding device for wire meshes which extend in a plane with a predefined width and have meshes, wherein said welding device comprises multiple electrodes which are connected to transformers via current paths.

A tab guide according to an embodiment of the present invention may press a plurality of electrode tabs so that the plurality of electrode tabs are gathered together.

The tab guide may include a contact part, which is in contact with the electrode tabs, and a mounting part in which the contact part is detachably mounted and which has higher rigidity than that of the contact part.