Secondary Battery Module Lead Welding Sequence and Stacking
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Solution Overview
Problem
The existing methods for welding electrode leads and bus bars in secondary battery modules face challenges due to differences in melting points, leading to deformation and reduced energy density, and inefficient connection processes, which complicate the construction of compact battery modules.
Innovation Solution
A method involving the sequential or parallel arrangement of aluminum and copper leads with copper bus bars, where the bus bars are welded first to prevent deformation, and the use of laser welding with specific irradiation directions to ensure high-quality connections and minimize module size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding is performed in the order of aluminum lead, copper lead and bus bars, then the connection is made, but the cell lead may be deformed first by the laser
Solution Approach 1:
The patent applies preliminary action by reversing the welding sequence to weld the copper lead and bus bar first, then weld the aluminum lead afterward. This preliminary welding of the copper components prevents lead deformation by establishing a stable base structure before the aluminum lead is welded, thereby ensuring both connection reliability and preventing shape distortion.
2Ease of manufacture
If unnecessary space is provided for welding, then welding can be performed, but energy density of the secondary battery module is lowered
Solution Approach 1:
The patent applies dimensionality change by arranging the aluminum lead, copper lead, and bus bar in a stacked configuration along the thickness direction rather than requiring lateral spacing. This vertical stacking enables welding access from one direction while minimizing the module's overall footprint, thereby maintaining welding accessibility without sacrificing energy density.
3Reliability
If different materials (aluminum and copper) are welded together, then electrical connection is achieved, but welding quality is deteriorated due to different melting points
Solution Approach 1:
The patent applies segmentation by dividing the welding process into two separate stages: first welding the copper lead to the bus bar (same material), then welding the aluminum lead to the copper lead (different materials). This segmentation allows each welding step to be optimized for its specific material combination, ensuring high welding quality and reliable electrical connection despite the involvement of different materials with different melting points.
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 approach improves welding quality, reduces unnecessary space in the module, and enhances energy efficiency by preventing lead damage and allowing for the effective integration of different materials, resulting in a more compact and efficient secondary battery module.
Implementation Method 1
when welding (especially, laser welding) is performed to electrode leads (Al)(Cu) and bus bars (Cu) of cells
Implementation Method 2
due to the different melting points of materials, generally, base materials are disposed in the order of an aluminum lead, a copper lead and bus bars
Data Source
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AI summary
Disclosed is a compact secondary battery module, which includes a cartridge assembly having a plurality of cartridges stacked while accommodating cells, respectively, so that a plurality of lead welding portions where a first lead and a second lead of adjacent cells overlap with each other are located at a cartridge sidewall with a predetermined pattern; and a sensing housing having a plurality of bus bars located and welded corresponding to the lead welding portions, respectively, the sensing housing being capable of being arranged at a side of the cartridge assembly, wherein when the sensing housing is coupled to the cartridge assembly, the first lead, the second lead and the bus bar are located in order from the sidewall of the cartridge in an outer direction and welded from the bus bar.