Battery Module Lead Welding Layout for Compact Bus Bar Joining
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Solution Overview
Problem
Existing secondary battery modules face challenges in efficient electrical connection and welding quality of electrode leads and bus bars due to different melting points of materials, leading to deformation and reduced energy density, especially in compact designs.
Innovation Solution
A method where electrode leads of adjacent cells overlap with each other, with a bus bar made of the same material as the second lead being partially cut and welded, minimizing lead deformation and optimizing module compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser welding is performed in the order of aluminum lead, copper lead and bus bars, then welding can be performed on different materials, but the cell lead may be deformed first by the laser due to different melting points
Solution Approach 1:
The patent applies preliminary action by arranging the welding sequence to weld the copper lead and bus bar first (which have higher melting points), and then weld the aluminum lead last. This preliminary arrangement of welding order prevents the aluminum lead from being exposed to laser heat before the copper components are secured, thereby preventing deformation while enabling welding of different materials.
2Ease of manufacture
If unnecessary space is provided for welding in secondary battery module, then welding can be performed, but energy density of the secondary battery module is lowered
Solution Approach 1:
The patent merges the welding operation with the existing module structure by utilizing the cartridge sidewall and lead overlapping portions that are already present in the module design. The sensing housing is integrated into the module structure, and the welding process uses the existing lead arrangement, eliminating the need for separate welding spaces and thereby maintaining high energy density.
3Reliability
If cells are arranged in series or parallel with different material leads and bus bars, then electrical connection is achieved, but welding quality deteriorates due to different melting points
Solution Approach 1:
The patent applies parameter changes by optimizing the welding parameters (laser power, welding speed, focal position) for each material combination in the welding sequence. The welding conditions are specifically adjusted when welding copper to copper (lead to bus bar) and then when welding aluminum to aluminum (lead to lead), matching the parameters to the melting points and thermal conductivities of the materials being joined, thereby ensuring high welding quality across different material interfaces.
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
Improves welding quality, reduces unnecessary space, minimizes material cost, and enhances energy efficiency by ensuring same-material welding and compact module design.
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, and then laser is irradiated
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 overlapping portions where leads 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 overlapping portions, respectively, the sensing housing being capable of being arranged at a side of the cartridge assembly, wherein a first lead of a cell of each lead overlapping portion is configured to have a shorter width than a second lead having a polarity opposite to the first lead as much as a predetermined width, and in a state where the sensing housing is coupled to the cartridge assembly, a corresponding bus bar comes into contact with the second lead substantially on the same line as the first lead, and the second lead and the bus bar are welded to each other.