Laser welding is the only non-contact, high precision and efficient welding method. It can be used to weld and seal battery structures economically and quickly. Laser processing usually includes laser cutting, laser welding, laser surface treatment and so on. In the whole power battery manufacturing, including cores, modules and packs, about 19 main parts need to be welded. Among them, 11 parts must be welded by laser at present; 5 parts may be welded by laser; and 3 parts will not be welded by laser. In square shell batteries, laser welding is used for seals, caps and seals, while in cylindrical batteries and modules, laser welding is used for ears, caps, confluence bars, etc.

"Battery leakage may lead to short circuit between batteries in the module, which can easily cause high temperature fire and other accidents. The existence of cracks and holes in batteries is a potential factor for seam sealing failure.

Failure of terminal of acquisition line will lead to failure of voltage acquisition and temperature acquisition, which may lead to overcharge of battery and fire and explosion.

Quality Improvement and Detection of Laser Welding

"Technological innovation can effectively improve welding quality. In fact, the more fully the pre-verification work is done, the stronger the process capability is. Liu Hao stressed. In order to highlight the impact of process innovation on welding quality, Liu Hao cited examples to illustrate.

Aluminum alloy profiles (end plates) and sheets (side plates) are commonly used in power battery module as outer frame components. The welding quality determines the rigidity of the whole module structure. Different welding effects can be obtained by using different welding joints and processes. Laser welding of side plates has also developed a variety of processes. The porosity of common welded joint is 10%, that of double beam welded joint is 3%, and that of swing spot welded joint is only 1%. More and more advanced laser welding equipment and technology, constantly improve the quality of welding, reduce porosity.

In addition, laser welding of core seal is an important process in battery manufacturing, which greatly affects the yield of battery. While the speed of cored welding is getting faster and faster, the weld properties such as weld consistency need to be guaranteed. From this, a variety of laser welding sealing processes have been developed. Among them, the high-speed swing welding of fiber laser makes the welding seam smooth and uniform. With the increase of welding frequency, the oscillating head can repair the explosion point.

(This article was originally created by Chenhao Laser, reproduced from www.lasersunrise.com. To cherish the fruits of other people's work is to respect oneself.)