The housing material of the power battery is aluminum alloy and stainless steel, among which aluminum alloy is the most common, generally 3003 aluminum alloy, and a few use pure aluminum. Stainless steel is the most weldable material of the green laser pointer, especially 304 stainless steel. Both the pulse and the continuous laser can obtain the weld with good appearance and performance.
The laser welding performance of aluminum and aluminum alloys varies slightly depending on the welding method used. Except for pure aluminum and 3 series aluminum alloy, there is no problem in pulse welding and continuous welding. The other series of aluminum alloys are optimally selected for continuous laser welding to reduce crack sensitivity. At the same time, according to the thickness of the power battery casing, a laser with a suitable power is selected. When the thickness of the casing is less than 1 mm, a single-mode laser of 1000 W or less can be considered, and a single-mode or multi-mode laser of 1000 W or more is required for a thickness of 1 mm or more.
Small-capacity lithium batteries often use a relatively thin aluminum shell (having a thickness of about 0.25 mm), and a steel shell such as 18650. Due to the thickness of the casing, the welding of such batteries generally uses a lower power green laser pointer. Using a continuous laser to solder a thin-shell lithium battery, the efficiency can be increased by 5 to 10 times, and the appearance and sealing are better. Therefore there is a trend to gradually replace pulsed lasers in this field of application.