Battery Terminal Clad Structure for Low-Heat Busbar Welding
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Solution Overview
Problem
Dissimilar metal welding between secondary battery terminals and busbars can lead to reliability issues and thermal damage, especially when aluminum rivets are used, causing high electric resistance and slow heat dissipation, which is exacerbated in high-capacity batteries during quick-charging.
Innovation Solution
The secondary battery design incorporates a clad structure for internal terminals with both aluminum and copper portions, allowing the rivets and busbar connection terminals to be made of copper, ensuring same-type metal welding and reducing thermal damage by using copper for the rivets and busbar connection terminals, and applying an insulating layer to protect exposed copper from corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If aluminum rivets are used to connect the positive electrode external terminal to the sealing body, then the current path material consistency is improved, but the electric resistance increases and heat dissipation capability deteriorates
Solution Approach 1:
The patent applies composite materials by using a clad structure for the internal terminal that combines aluminum and copper layers. The aluminum layer contacts the aluminum rivet to maintain material consistency, while the copper layer provides superior electrical conductivity and heat dissipation capability. This composite structure resolves the contradiction by integrating the advantages of both materials in different functional zones.
Solution Approach 2:
The patent applies local quality by making different portions of the internal terminal have different material properties. The aluminum portion (first portion) is positioned where material consistency with the rivet is needed, while the copper portion (second portion) is positioned where high conductivity and heat dissipation are required. This localized material differentiation resolves the contradiction between material consistency and thermal performance.
2Adaptability or versatility
If dissimilar metals are used for positive and negative electrode external terminals, then the electrode terminal material properties are optimized, but the welding reliability to single-type busbar deteriorates
Solution Approach 1:
The clad structure internal terminal uses composite materials to enable both positive and negative terminals to present the same metal surface to the busbar. The copper layer in the positive terminal and the copper layer in the negative terminal both contact the busbar, allowing reliable welding of dissimilar metal terminals to a single-type copper busbar while maintaining optimized material properties throughout the current path.
3Stability of the object's composition
If aluminum is used for the positive electrode current path members, then the material consistency is maintained, but the thermal damage resistance of the gasket deteriorates
Solution Approach 1:
The internal terminal uses a clad structure with aluminum and copper layers. The copper layer (second portion) is positioned adjacent to the gasket to provide superior thermal conductivity and heat dissipation, protecting the gasket from thermal damage. The aluminum layer (first portion) maintains material consistency with the aluminum rivet and positive electrode tab, resolving the contradiction between material consistency and thermal protection.
Solution Approach 2:
The patent applies local quality by positioning the copper material specifically in the region where heat dissipation is most critical (near the gasket and clinched portion), while maintaining aluminum in regions where material consistency is prioritized. This localized material optimization protects the gasket from thermal damage without compromising overall material consistency.
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 design enables reliable welding of secondary battery terminals to a single-type busbar, suppressing heat generation and reducing thermal damage to the gasket, while ensuring the strength of welded portions and preventing corrosion of copper components.
Implementation Method 1
aluminum has a higher electric resistance and a lower thermal conductivity than copper, and thus, the following problems occur particularly when the positive rivet is made of aluminum... since aluminum has a low thermal conductivity, its heat dissipation rate is slow. Consequently, a problem occurs in that gasket, which is disposed in the vicinity of the clinched portion of the rivet, sustains thermal damage
Implementation Method 2
The internal terminal includes a first portion made of a first metal and a second portion made of a second metal. The external terminal is made of a second metal, and the rivet of the external terminal is joined to the second portion of the internal terminal... aluminum has a higher electric resistance... than copper
Data Source
AI summary
A secondary battery includes an electrode body that includes a positive and a negative electrode plate, a battery case that has an opening in which the electrode body is accommodated, a sealing body that seals the opening, an internal terminal that is disposed on an inner side of the sealing body and connected to the positive or the negative electrode plate, and an external terminal that is disposed on an outer side of the sealing body and connected to the internal terminal. The external terminal includes a rivet that is formed in such a manner as to extend through the sealing body, and the internal terminal includes a first portion made of a first metal and a second portion made of a second metal. The external terminal is made of the second metal, and the rivet of the external terminal is joined to the second portion of the internal terminal.