Cu-Al Busbar Joint Structure for Vibration-Resistant Battery Modules
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Solution Overview
Problem
Busbars joining battery terminals made of dissimilar metals face stress issues due to vibrations and bulging during charging/discharging, leading to potential joint failure.
Innovation Solution
The busbar design includes a copper and aluminum configuration with a joint on the connection face portion connected to the battery terminal, and the copper and aluminum portions are partially bent in a hook shape, allowing the joint to receive reactive forces opposite to the stress, thereby maintaining high joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dissimilar metals (copper and aluminum) are joined in a busbar to connect battery terminals, then electrical conductivity and material compatibility are improved, but joint strength deteriorates under vibration and stress
Solution Approach 1:
The busbar is designed with a curved arc shape instead of a straight configuration. This curvature allows the busbar to flex and absorb stress during battery expansion and contraction, reducing stress concentration at the dissimilar metal joint between copper and aluminum portions, thereby maintaining joint strength while accommodating material compatibility requirements
Solution Approach 2:
The thickness of the busbar is varied along its length, with greater thickness at the joint between dissimilar metals and gradually decreasing toward the ends. This parameter change optimizes the structural strength at the critical joint region while maintaining overall flexibility and electrical conductivity, preventing joint failure under vibration and stress
2Strength
If the busbar is made rigid to maintain joint strength, then joint strength is improved, but stress concentration increases under vibration and thermal expansion
Solution Approach 1:
The arc-shaped configuration provides inherent flexibility that allows the busbar to deform elastically under stress from vibration and thermal expansion, distributing stress along the curved path rather than concentrating it at the joint, while the varied thickness maintains sufficient rigidity where needed
Solution Approach 2:
The busbar design incorporates flexible geometric features including the arc shape and varied cross-section that allow controlled deformation, enabling the structure to absorb mechanical stress and thermal expansion without rigid failure, while maintaining electrical connectivity and joint integrity
Data Source
AI summary
Provided is a battery module capable of keeping a joint strength high at a joint between dissimilar metals of a busbar. The battery module 100 includes a plurality of battery cells each having cell terminals 1p and 1n, and a busbar 2A joining the terminals of the battery cells 1. The busbar 2A has a plurality of connection face portions 2c1 and 2c2 each connected to a corresponding one of the terminals 1p and 1n of the battery cells 1; a plurality of rising portions each rising from a corresponding one of the plurality of connection face portions 2c1 and 2c2; and a connection portion connecting the plurality of rising portions. The busbar includes a copper portion 2e including copper and an aluminum portion 2f including aluminum, and a joint between the copper portion 2e and the aluminum portion 2f are located on the connection face portion 2c1, 2c2.