Battery Cell Tab Welding Using Homogeneous Aluminum Interconnects
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Solution Overview
Problem
The challenge in welding components of vehicle battery packs lies in achieving cost-effective, reliable, and durable welds that resist environmental degradation, including vibrations, temperature variations, and moisture, while avoiding the risks associated with welding dissimilar metals and electrolytic corrosion.
Innovation Solution
The use of nickel-plated copper and aluminum foil cell tabs with an aluminum interconnect, where welds are made between similar metals, simplifying the welding process and eliminating electrolytic corrosion risks by ensuring the same coefficient of thermal expansion across weld joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dissimilar metals (nickel-plated copper and aluminum) are welded together to connect battery cells, then electrical conductivity and current collection are improved, but the risk of electrolytic corrosion increases and weld reliability deteriorates
Solution Approach 1:
The patent applies homogeneity by making the interconnect body (legs and bridge) the same material (aluminum) as the cell tabs, ensuring that similar metals are welded together. This eliminates galvanic corrosion between dissimilar metals while maintaining electrical conductivity. The nickel-plated copper contact portions are isolated from direct welding with the aluminum interconnect body, preventing electrolytic corrosion at weld joints.
2Adaptability or versatility
If dissimilar metals with different thermal expansion coefficients are welded together, then design flexibility is improved, but dimensional stability and weld joint integrity worsen under temperature variations
Solution Approach 1:
The interconnect body is constructed entirely of aluminum, matching the material of the cell tabs, to ensure uniform thermal expansion characteristics. This homogeneity prevents differential thermal expansion and maintains dimensional stability during battery pack operation across temperature variations, while still allowing design flexibility through the nickel-plated copper contact portions for electrical connectivity.
3Reliability
If complex multi-material interconnects are used to optimize electrical performance, then electrical conductivity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The interconnect employs local quality by using nickel-plated copper contact portions only where electrical connection is required (at the weld interface with cell tabs), while the bulk of the interconnect body (legs and bridge) is made of aluminum. This localized material differentiation optimizes electrical conductivity at critical interfaces while keeping the overall structure simple and cost-effective to manufacture.
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 enhances weld quality, reduces the risk of corrosion, and maintains consistent thermal expansion across weld joints, resulting in improved reliability and durability of battery pack assemblies.
Implementation Method 1
an aluminum contact portion bonded to and extending from the respective base portion
Implementation Method 2
A first set of welds secures the contact portions of the first foil cell tabs to the first leg and a second set of welds secures the foil cell tabs of the second set of battery cells to the second leg
Data Source
AI summary
A battery pack for a vehicle has battery cells with foil cell tabs that are welded to an interconnect. Nickel plated copper is bonded to aluminum for either a first set of the battery cells, a second set of the battery cells or for the interconnect. Similar materials are then adjacent to each other at the weld locations between the foil cell tabs and the interconnect to avoid welding of dissimilar metals.