Welding method and welding structure of lithium ion battery covers

Abstract

The invention relates to a welding method and welding structure of lithium ion battery covers. The welding method comprises a step that a cathode lug is welded on a pore plate of a cover; during welding, a laser-beam welding machine is used for generating a laser light, the laser light melts the cathode lug and the pore plate, and the cathode lug and the pore plate are connected together after being cooled; the welding method is characterized in that two or more solder joints are formed, any two adjacent solder joints partially coincide with each other, and all the solder joints are linearly arrayed; heat generated when the first solder joint is formed by welding can produce a high temperature around solder joints to pre-heat the cathode lug, so that excessive energy is not needed in the area where the second solder joint is formed by welding, the welding is easier, and the subsequent solder joints can utilize the heat generated by the previous soldering joints; the welding machine moves in only one direction. According to the welding method and the welding structure of the lithium ion battery covers, the welding strength of battery covers and lugs is obviously improved, the production difficulty of lithium ion batteries is reduced, and the production efficiency of lithium ion batteries is improved.

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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