Application of laser welding in lithium battery manufacturing

Power batteries are the core components of new energy vehicles, and their quality directly affects the performance of the entire vehicle. Lithium battery manufacturing equipment is generally divided into three categories: front-end equipment, intermediate equipment, and back-end equipment. The equipment accuracy and degree of automation directly affect the production efficiency and consistency of the product. However, due to its technical advantages, laser processing technology is increasingly used in the lithium battery industry for battery cells, modules, etc.laser welding, pole piece material cutting, marking, etc.

1.Laser welding process

From lithium battery cell manufacturing to battery PACK grouping, welding is a very important manufacturing process. The conductivity, strength, air tightness, metal fatigue and corrosion resistance of lithium batteries are typical standards for battery welding quality assessment.

The selection of welding methods and welding processes directly affects the cost, quality, safety and consistency of batteries. Laser welding has many advantages: First, laser welding has high energy density, small welding deformation, small heat-affected zone, can effectively improve the forming accuracy, the weld is smooth and free of impurities, uniform and dense, and no additional grinding work is required; laser welding can be precisely controlled and no additional grinding work is required;

The battery pack structure is usually composed of a variety of materials, such as steel, aluminum, copper, nickel, etc., which can be used to make electrodes, wires or shells; Therefore, no matter the welding of one or more materials, there are high requirements for the welding process. The process advantage lies in the wide variety of laser welding materials, which can realize welding between different materials.

2. Pole ear cutting

In lithium battery manufacturing, laser welding is also widely used, almost throughout every link of production. Lithium batteries, especially power lithium batteries, need to cut the tabs, but the traditional die-cutting method is not only costly, but also prone to safety problems. During use, the die-cutting tool will inevitably wear out, and then dust and burrs will be produced. Dangerous problems such as battery overheating, short circuit, and explosion are caused by dust and burrs. Die-cutting knives need to be replaced frequently to avoid danger. But its price is as high as hundreds of thousands or even millions of yuan, and such a die-cutting machine costs millions of yuan every year. A lithium battery production line is usually equipped with 8 to 10 die-cutting machines, which makes the material cost of the die-cutting machine account for a considerable proportion of the entire lithium battery production cost.

Compared with traditional die-cutting methods, high-power, online laser cutting does not require material consumption at one time, which greatly reduces costs; second, it is fast and can greatly improve production efficiency; third, it is flexible, not only can the previous new product design and trial cutting process be shortened from several months to a few days, but also the spacing and size can be freely controlled. In terms of cost, the one-time investment only increases by 30%, and the cost can be recovered in a short time.