Welding method of battery module

【Summary Description】 Abstract: This paper introduces the welding methods of battery module, including regular welding, laser welding, friction welding, ultrasonic welding and so on. Firstly, the principles and characteristics of various welding methods are briefly summarized, and then the specific steps of the welding operation of the battery module are introduced in detail, including the preparation before welding, the welding process and the inspection after welding. Finally, various welding methods are compared and evaluated, and their advantages and disadvantages and scope of application are pointed out. 1. Introduction With the rapid development of electric vehicles and energy storage systems, the demand for battery modules is increasing. In the manufacturing process of the battery module, welding is one of the key process links. The quality of welding directly affects the performance and service life of the battery module. Therefore, it is of great significance to study and select a suitable welding method for the manufacture of battery modules. Principles and characteristics of 2. welding methods 1. Fusion welding Fusion welding is a welding method in which metal joints above the melting point are heated, fully melted and mixed, and then solidified in the liquid state to achieve the connection. Fusion welding has the advantages of mature technology, wide application range and low cost. However, fusion welding is prone to uneven heating, resulting in deformation and damage of the battery module. 2. Laser welding Laser welding is a welding method that uses a high-energy laser beam to act on the metal surface to melt and solidify the metal into one. Laser welding has the advantages of high energy density, fast welding speed, small heat affected zone and high weld quality. However, the laser welding equipment is expensive and the cost is high. 3. Friction welding Friction welding is a welding method that generates heat energy through friction, heats the metal surface to a plastic state, and then applies pressure to achieve a connection. Friction welding has the advantages of energy saving, environmental protection and simple operation. However, the manufacturing cost of friction welding is high. 4. Ultrasonic welding Ultrasonic welding is a welding method that uses high-frequency vibration energy to transmit to metal connectors to generate frictional heat energy to achieve connection. Ultrasonic welding has the advantages of high efficiency, energy saving and simple operation. However, the equipment cost of ultrasonic welding is high. 3. battery module welding operation process 1. Preparation before welding Before welding the battery module, the following preparations are required: clean up the impurities such as oxide and grease on the surface of the battery module and the connection area; check whether the specifications and models of the connectors match; prepare the required welding equipment and materials. 2. Welding process After the relevant preparations are prepared, the welding operation of the battery module may be performed. The following is a detailed description of fusion welding as an example: a. Place the battery module in a special fixture and fix it; B. Use a flame spray gun to uniformly preheat the connection area of the battery module; c. Place the connector in the preheated connection area and adjust the position; d. Use manual arc welding or gas shielded welding for welding; E. after the completion of welding, check whether there are false welding, air holes and other defects. Other welding methods are similar to fusion welding. Please refer to the book or manual of the corresponding welding method for specific operation. 3. Inspection after welding After the welding is completed, the quality inspection of the battery module is required. The inspection contents include: appearance inspection, non-destructive testing (such as X-ray testing, ultrasonic testing, etc.), performance testing (such as tensile strength, air tightness, etc.). Unqualified battery modules need to be repaired or scrapped. Comparison and evaluation of different welding methods in 4. The following table compares and evaluates the advantages and disadvantages of the four welding methods: | Serial | Welding Method | Advantages | Disadvantages | | --- | --- | --- | --- | | 1 | Fusion welding | Mature technology, low cost, wide application range | Easy to deform and damage battery modules due to uneven heating | | 2 | Laser welding | High energy density, fast welding speed, high weld quality | Expensive equipment and high cost | | 3 | Friction welding | Energy saving, environmental protection, easy operation | High manufacturing cost | | 4 | Ultrasonic welding | Energy saving, environmental protection, simple operation, high production efficiency | High equipment cost It is difficult to achieve stable welding joint processing for battery module connection of brittle materials and dissimilar materials:(1) Surface cleaning: Clean out materials that can absorb laser beams on both sides of the groove. (2) Assembly: assemble and align the groove to be welded. (3) Arc striking: ignite the laser beam in the groove. (4) wire feeding: the filler wire to be protected is sent to the molten pool. (5) Molten pool formation: After feeding the filling wire, the molten pool is formed. (6) molten pool stirring: make the filling wire in the molten pool evenly mixed. (7) Melting of filling wire and control of wire feeding speed. (8) Melting speed control of the filler wire. (9) Filler wire feeding speed control. (10) Solidification process of molten pool. (11) Turn off the laser: Turn off the laser after waiting for the molten pool to completely solidify. (12) Protective gas: (inert gas). (13) Cleaning: Slag and

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