Process for welding caps and plate lugs of lithium batteries

Abstract

The invention provides a process for welding caps and plate lugs of lithium batteries. The process comprises the following steps of (1) selecting the model of a laser device: selecting a 50-150W Fiber laser device as a welding light source; (2) configuring a laser optical device; (3) pretreating the plate lugs and the caps before welding; (4) conducting butting joint on the caps and the plate lugs, reasonably selecting a welding area and reasonably selecting a welding area press-fitting process; (5) adopting a welding trace capable of enhancing the welding strength: selecting and arranging 2-8 chamfered rectangles into a certain shape, adopting a spiral line filled trace; (6) setting laser parameters: setting the power to be 40-120 W, the frequency to be 60-650 KHz and the pulse width to be 20-200 ns: and (7) adopting an air blowing protection system for protection in the welding process.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a process method for welding lithium battery caps and tabs in the 18650, 26650 and 32700 battery industries. Background technique [0002] At present, ultrasonic welding, resistance butt welding, and YAG laser welding processes are usually used in the market to weld the plate inside the cap of the battery and the positive tab of the cell. The material of the plate inside the cap is aluminum, copper or stainless steel (with different thicknesses), while the material of the positive tab of the battery is aluminum or nickel strip with a thickness of 0.08-0.15mm. [0003] Such as figure 1 As shown, the working principle of ultrasonic friction welding is to transmit ultrasonic energy to the welding area through the upper weldment. Since the welding area, that is, the interface between the two welds, has a large acoustic resistance, local high temperature will be generated. And beca...

AI Technical Summary

Problems solved by technology

The disadvantages are: welding requires a lot of construction space, and the aluminum component of the keyboard is a three-dimensional composite semi-closed riveting workpiece, which does not allow such a large construction space; ultrasonic friction welding is double-sided contact welding, which requires a lot of work. Strong stress will directly dent the workpieces on both sides, seriously affecting the appearance; mold pressing welding is required, the mold is not very small, it is difficult to meet the situation where the keyboard aluminum components have a docking area of ​​only 2-3mm², and are extremely easy to damage Mold; the welding speed is slow, it takes 4-10 seconds to weld a 5mm² area, and it takes 10-20 seconds to clamp; it is difficult to realize the automatic welding of aluminum keyboard components

Disadvantages: The outlet point is relatively large, and the outlet point is easy to break, resulting in false welding and inconsistent welding; resistance welding requires a large construction space, and the aluminum component of the keyboard is a three-dimensional composite semi-closed riveting workpiece, which is not allowed Such a large construction space; it is not suitable for welding workpieces that store and discharge electricity

The disadvantages are: the YAG welding process is suitable for welding a single point or a line formed by a single point, and is not suitable for large-area welding; when YAG laser welding is about 0.4mm thick and highly reflective aluminum material, after the laser energy penetrates The penetration depth of the bottom 1.8mm plate is small, the welding strength is low when the welding area is less than 2mm², and the tensile force is small, often less than 10N; the YAG machine occupies a large area (the whole system takes about 3-5 square meters), and the energy consumption is high. (about 10KW), with consumables (xenon lamp, optical fiber, protective lens, filter element, water, etc.), the welding spots will become weaker with the attenuation of the xenon lamp, resulting in inconsistent solder joints and unstable long-term operation; welding efficiency is higher than traditional welding, But the efficiency is only 20-50% of this process

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