Battery Interconnection Assemblies Using Harder Metal Tabs and Weld Assisting Layers
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Solution Overview
Problem
Ultrasonic welding of interconnect members to battery terminals made of soft metals like aluminum often results in the welding horn penetrating through the terminal, leading to deformation and incomplete welds.
Innovation Solution
The use of interconnect members with U-shaped portions and weld assisting layers, where the interconnect members are made of harder metals than the battery cell tabs, such as copper or nickel alloys, to prevent deformation and ensure complete welds by positioning the cell tabs within the U-shaped portion or between the weld assisting layer and the interconnect member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic welding is used to join interconnect members to aluminum battery terminals, then welding speed and productivity are improved, but the welding horn penetrates through the soft metal terminal causing deformation and incomplete welds
Solution Approach 1:
A copper transition layer is introduced between the aluminum battery terminal and the interconnect member. This intermediary layer has intermediate hardness properties - softer than the interconnect member to allow proper welding, but harder than the aluminum terminal to prevent horn penetration. The copper layer acts as a mediator that enables complete welds without deforming the soft aluminum terminal, thus resolving the contradiction between welding speed and welding completeness.
2Strength
If the interconnect member is made of harder metal to prevent deformation, then structural strength is improved, but welding to soft metal terminals becomes difficult due to hardness mismatch
Solution Approach 1:
The interconnection assembly uses different materials with different properties at different locations: soft aluminum at the terminal for ease of handling and electrical conductivity, hard copper in the transition layer for structural strength and welding facilitation, and very hard interconnect member for final structural integrity. This local differentiation of material properties allows each component to optimize its function, resolving the contradiction between strength and weldability.
3Manufacturing precision
If a weld assisting layer is added to prevent horn penetration, then welding precision is improved, but device complexity increases
Solution Approach 1:
The interconnection assembly uses a composite structure with multiple material layers (aluminum terminal, copper transition layer, interconnect member) bonded together. This composite approach integrates the weld assisting function directly into the structural assembly rather than adding separate external components. The copper transition layer serves dual purposes: it prevents horn penetration (improving welding precision) while also providing structural strength and electrical conductivity, thus minimizing the increase in device complexity.
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 solution effectively prevents the ultrasonic welding horn from penetrating the battery cell tabs, reducing deformation and ensuring a strong, complete welding joint, thereby enhancing the reliability of battery module interconnections.
Implementation Method 1
ultrasonically welding together the first and second cell tabs, the interconnect member, and the weld assisting layer utilizing an ultrasonic welding machine
Data Source
AI summary
Interconnection assemblies and methods are provided. An interconnection assembly includes a first cell tab constructed of a first metal, and a second cell tab disposed against the first cell tab. The second cell tab is constructed of a second metal having a hardness greater than the first metal. The assembly further includes an interconnect member disposed against the second cell tab. The assembly further includes a weld assisting layer disposed against the first cell tab such that the first and second cell tabs are disposed between the weld assisting layer and the interconnect member.