The anode and cathode materials of battery cells are aluminum and copper/nickel, respectively. The anode of pole column needs aluminum column, and the cathode is made of copper-aluminum composite material, all of which are T-shaped inverted and the bottom is copper. The T-shape is needed because a conductive block, also made of aluminum, needs to be added to the pole post. The aluminum block/sheet has a small hole, and the pole passes through the bottom of the cover plate. At this time, put the holes in the aluminum sheet and stick them on. Because this joint is where we need laser welding, aluminum has relatively good conductivity, light weight and appropriate hardness, which is more suitable for power batteries. Therefore, when laser welding, it is necessary to clean the surface of aluminum in order to weld the pole better.