Secondary Cell Terminal Flange Segmentation for Welding Reliability
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Solution Overview
Problem
Existing secondary cell battery packs face challenges in achieving a highly reliable connection between terminals and external electroconductive members, which can lead to reduced efficiency and increased risk of degradation due to differences in metal types used for positive and negative electrodes.
Innovation Solution
A secondary cell design featuring a terminal with a flange having distinct areas of aluminium and copper alloys, where the boundary between these areas is strategically positioned to enhance the connection reliability, and an external electroconductive member made of aluminium is welded to the flange, ensuring a strong and reliable connection without extending the weld to the copper area, thus preventing potential degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a terminal with distinct aluminium and copper alloy areas is used, then the connection reliability is improved, but the device complexity increases
Solution Approach 1:
The terminal flange is segmented into distinct material zones: a first area made of aluminium or aluminium alloy and a second area made of copper or copper alloy. This segmentation allows each area to be optimized for its specific function - the aluminium area for welding to the external electroconductive member and the copper area for electrical conductivity and connection to the electrode plate, thereby improving connection reliability while maintaining a relatively simple overall structure.
Solution Approach 2:
Different areas of the terminal flange have different material properties tailored to local requirements. The aluminium area provides good weldability with the external electroconductive member, while the copper area provides superior electrical conductivity for the connection to the electrode plate. This local differentiation of material quality resolves the contradiction by improving connection reliability through material optimization without requiring complex multi-component assemblies.
2Reliability
If the boundary between aluminium and copper areas is positioned between the first and second surfaces, then the welding quality is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The boundary between the aluminium and copper areas is positioned in the thickness direction (depth dimension) of the flange rather than only in the planar dimensions. By placing the boundary between the first surface (outer surface) and second surface (inner surface), the design utilizes the third dimension to separate the material zones. This dimensional approach allows the weld to be confined to the aluminium area on the outer surface while the copper area remains on the inner surface, improving welding quality without requiring extremely tight tolerances on surface-level boundary positioning.
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 enhances the reliability and efficiency of the connection between the terminal and external electroconductive member, reducing the risk of degradation and improving the overall output characteristics of the secondary cell and battery pack.
Implementation Method 1
The external electroconductive member is welded to the flange to form a welded portion
Data Source
AI summary
A negative electrode terminal includes a flange, and a connection portion disposed on a first surface of the flange. The connection portion is inserted into a terminal attachment hole. The negative electrode terminal includes a first area made of aluminium or an aluminium alloy, and a second area made of copper or a copper alloy. In the flange, the second area is disposed adjacent to the first surface, and the first area is disposed adjacent to the second surface. A boundary between the first area and the second area is disposed between the first surface and the second surface. A thinnest portion of the first area of the flange in the thickness direction of the flange has a thickness of larger than or equal to 0.3 mm. An external electroconductive member made of aluminium or an aluminium alloy is welded to the flange to form a welded portion.