Battery Tab Laser Welding for Fast, Low-Spatter Copper Joints
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Solution Overview
Problem
Infrared laser welding systems face challenges when welding materials like copper due to high reflectivity, making it difficult to achieve reliable and quick welds, especially in battery module manufacturing where small area welds are required.
Innovation Solution
A method using a laser welding system with a scanning head and movable mirrors to direct the laser beam efficiently, allowing for high-speed welding by positioning the scanning head in fixed positions to weld multiple tabs simultaneously, and controlling the laser beam to oscillate for optimal energy distribution and avoiding overpenetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If infrared laser welding systems are used to weld copper materials, then welding speed can be improved, but welding reliability deteriorates due to high reflectivity of copper at infrared wavelengths
Solution Approach 1:
The patent changes the wavelength parameter of the laser from infrared to green wavelength. This parameter change allows the laser beam to be effectively absorbed by copper materials instead of being reflected, thereby achieving both high welding speed and high welding reliability when welding copper tabs to aluminum terminals in battery modules
2Adaptability or versatility
If welds are located on relatively small areas on the cells, then battery module design requirements are met, but welding reliability becomes more difficult to achieve
Solution Approach 1:
The patent uses green wavelength laser with specific optical parameters to achieve precise welding on small areas. The wavelength and focus parameters are optimized to concentrate energy on small welding areas while maintaining reliability, enabling welding on the small terminal areas required by battery module design
3Manufacturing precision
If scanning head is repositioned after every weld, then precise welding can be achieved, but welding speed decreases
Solution Approach 1:
The patent employs preliminary positioning where the scanning head is repositioned to different fixed positions before groups of welds rather than after each individual weld. This preliminary action maintains welding precision while significantly improving productivity by reducing the frequency of repositioning operations during the welding process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables faster and more reliable welding of busbar components to cell terminals, reducing the time per weld to 80 milliseconds or less and ensuring strong connections without overheating or overpenetration, even with high-reflectivity materials like copper.
Implementation Method 1
welding a first group of tabs to the respective terminals by moving the plurality of mirrors to sequentially direct the laser beam of the laser welding system towards each of the tabs in the first group
Implementation Method 2
producing a first group of welds
Implementation Method 3
controlling the laser beam to oscillate for optimal energy distribution and avoiding overpenetration
Data Source
AI summary
The present invention disclosure relates to a method of welding a tab to a terminal of an electrical cell using an infra-red laser welding system. A first surface of the tab is placed in contact with the terminal of the electrical cell, and an infra-red laser is directed through at least one lens towards a second surface of the tab opposite the first surface. The laser welding system is controlled to produce a weld by directing the beam to follow a predetermined path. During welding, the beam is focussed in a plane between the first surface and the lens. In some embodiments, the beam may be focussed between the second surface and the lens. Advantageously, focussing the beam in this way has been found to reduce undesirable phenomena such as spatter and to produce more reliable welds than prior art methods.