Composite Busbar Structure for Dissimilar Lead Welding
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Solution Overview
Problem
The connection of electrode leads made of different materials to busbars in battery modules leads to increased incidence of cracks and deteriorates weldability, as well as galvanic corrosion at the welded interface.
Innovation Solution
A busbar design featuring a first conductor layer made of a first metal with an exposed area and a second conductor layer made of a different second metal, stacked and fixed to the first layer, allowing homogeneous bonding of electrode leads made of the same material to improve weldability and electrical conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode leads made of different materials are bonded to the busbar, then electrical connection is established, but weldability deteriorates and cracks increase
Solution Approach 1:
The busbar employs a composite structure with a first conductor layer (e.g., aluminum) and a second conductor layer (e.g., copper) stacked and fixed to each other. This composite material design allows the busbar to provide both aluminum-like properties (lightweight, cost-effective) and copper-like properties (superior electrical and thermal conductivity), thereby improving overall reliability while mitigating galvanic corrosion issues through controlled interfaces
Solution Approach 2:
Different regions of the busbar have different material compositions optimized for specific functions. The first conductor layer provides structural support and cost-effectiveness, while the second conductor layer enhances electrical conductivity at critical connection points. This local differentiation of material properties resolves the contradiction between cost/weight and performance
2Reliability
If electrode leads made of different materials are bonded to the busbar, then electrical connection is established, but the incidence of cracks increases
Solution Approach 1:
The stacked conductor layer structure combines materials with complementary mechanical properties. The first conductor layer (e.g., aluminum) provides ductility and formability, while the second conductor layer (e.g., copper) provides strength and crack resistance. This composite approach improves overall mechanical resistance without sacrificing other critical properties
Solution Approach 2:
The second conductor layer extends from the first lateral edge toward the second lateral edge, leaving an exposed area of the first conductor layer. This curved/extended configuration distributes stress more evenly along the bond interface, reducing stress concentration points that would otherwise initiate cracks
3Ease of manufacture
If electrode leads made of different materials are bonded to the busbar, then connection is achieved, but weldability deteriorates
Solution Approach 1:
The busbar provides locally optimized material surfaces for welding. The exposed area of the first conductor layer and the surface of the second conductor layer can be selected based on the material composition of the electrode leads being connected, ensuring optimal weldability for each specific connection while maintaining high bonding quality
Solution Approach 2:
By changing the material composition parameter of the busbar from a single material to a composite stacked structure, the weldability parameter is improved. The different conductor layers offer different welding characteristics, allowing optimization for various electrode lead materials and welding processes
Data Source
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AI summary
A busbar according to an embodiment of the present disclosure includes: a first conductor layer made of a first metal; and a second conductor layer made of a second metal different from the first metal and stacked and fixed to one surface of the first conductor layer, wherein, on one surface of the first conductor layer to which the second conductor layer is fixed, the first conductor layer has an exposed area where the first metal is exposed.