Welding method and structure for lithium ion battery cap

Abstract

The invention relates to a welding method and structure for a lithium ion battery cap. The welding method comprises the step of welding an anode tab on an orifice plate of a cap. During welding, laser is generated by a laser welding machine, the anode tab and the orifice plate are melted by the laser, and the anode tab and the orifice plate are connected together after being cooled. The welding method is characterized in that all welding points are partially superposed, the anode tab can be preheated by high temperature formed around a welding point by the heat generated when the first welding point is welded, the second welding point is more easily welded because of needing no overhigh energy in the region, and the heats of the former welding points can be utilized by all the subsequent welding points. By using the welding method, the welding strength of the battery cap and the tab is remarkably improved, the production difficulty of the lithium ion battery is lowered, and the production efficiency of the lithium ion battery is increased.

Description

technical field [0001] The invention relates to a welding method for a cover or an end cover of a battery, in particular to a welding method and a welding structure for a lithium ion battery cover. Background technique [0002] Lithium-ion batteries were developed and commercialized by Japan's SONY company in the 1990s. Its appearance is a leap in the history of secondary battery development. Lithium-ion batteries have developed rapidly in 3C fields such as mobile phones and notebook computers due to their light weight, high capacity, high working voltage, long service life and no pollution. Its global sales have exceeded the sum of nickel-metal hydride and nickel-cadmium batteries , In recent years, my country's electric vehicles have developed rapidly, and the production and sales have reached the first place in the world. [0003] As the demand for electric vehicles grows, higher requirements are put forward for lithium-ion batteries, which require reliable structure, goo...

AI Technical Summary

Problems solved by technology

The structure of the cap is as figure 1 As shown, the positive tab 6 needs to be welded on the orifice plate 1 of the cap, and generally 2 to 4 solder spots are welded on the positive tab 6 to ensure the strength of the welding. The general distribution method is as follows figure 2 As shown, the diameter of the solder joint 7 is 0.4 to 1 mm, and the distance between the solder joints is 0.5 to 1 mm. Each solder joint is scattered, and the material of the positive electrode tab 6 and the orifice plate 1 is aluminum. When welding, use a laser The welding machine generates a laser, and the laser melts the positive tab 6 and the orifice plate 1. After cooling, the positive tab 6 and the orifice 1 are connected together. Generally, the width of the positive tab is 2 to 3 mm, so only 2 to 4 welds can be welded. If the tabs are skewed during the welding process, it cannot be guaranteed that all the solder joints are welded on the tabs 6. At the same time, in order to achieve the welding strength, a high-power laser welding machine is required. Insufficient energy may lead to false welding, and excessive energy may cause Explosion or fusion is a process that is not easy to control accurately

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