Analysis of the Technical Difficulties in Power Battery Welding
Release time: 2017-11-07
Analysis of Challenges in Power Battery Welding Processes
Published on 2017-11-07
Side welding and lid welding are the two main welding methods for power battery casings, each with its own advantages and disadvantages. Most power batteries use aluminum casing materials, which, due to their material properties, often encounter issues such as bulging, spatter, and porosity during processing. Particularly, square batteries are prone to problems at the corners.
Below are some of the challenges in power battery encapsulation welding
1. Challenges in Power Battery Welding Processes
Typically, the thickness of power battery aluminum casings is required to be below 1.0mm, with mainstream manufacturers using 0.6mm and 0.8mm thicknesses depending on battery capacity. Welding methods are mainly divided into side welding and lid welding. Side welding has the advantage of minimal impact on the internal cells, as spatter is less likely to enter the casing interior.
However, welding may cause bulging, which slightly affects subsequent assembly processes. Therefore, side welding requires high stability of the laser, cleanliness of materials, and precise gaps between the lid and the aluminum casing. Lid welding, on the other hand, is performed on a single surface and can utilize more efficient galvanometer scanning welding, but it demands high precision in casing placement and positioning, as well as advanced automation.
2. Challenges in Welding Aluminum Casings for Power Batteries
Aluminum casings account for over 90% of power battery casings. Laser welding of aluminum is challenging, often leading to issues such as surface bulging, porosity, spatter, and internal bubbles. Surface bulging, porosity, and internal bubbles are critical defects in laser welding, often forcing applications to halt or find alternative solutions.
Many battery manufacturers face significant challenges during the R&D phase, primarily due to the use of fiber cores that are too small or laser energy settings that are too high. Factors causing spatter (also known as splash) include material cleanliness, purity, and inherent properties, with laser stability being the most decisive factor.
In power battery welding, technicians select appropriate lasers and welding parameters—such as welding speed, waveform, peak power, and welding head tilt angle—based on the battery's material, shape, thickness, and tensile requirements to ensure the final weld meets the manufacturer's standards.
3. Challenges in Welding Square Power Batteries
Due to factors such as material fit precision, square batteries are most prone to issues at the corners during welding. Continuous exploration and adjustment of welding speed can help resolve these issues. Round batteries do not face such problems, but integrating them into battery modules is more challenging.
By understanding and addressing these challenges, we can overcome the difficulties in power battery welding.
Key Takeaways
1. Causes of Spatter in Aluminum Casing Welding Material cleanliness, purity, and inherent properties, with laser stability being the most critical factor.
2. Corner Welding in Square Batteries Requires slower welding speeds.
3. Advantage of Side Welding Minimal impact on cells, with spatter not entering the casing.
4. Requirements for Lid Welding Requires galvanometer systems and high automation.
5. Critical Defects in Laser Welding Surface bulging, porosity, and internal bubbles. Therefore, technicians must select appropriate lasers and welding parameters based on the battery's material, thickness, shape, and tensile requirements.
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