Prismatic Battery Split Electrode Segmented Resistance Welding
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Solution Overview
Problem
Large-capacity prismatic sealed secondary batteries, such as lithium ion batteries for EVs and HEVs, face challenges in achieving stable welding between electrode substrates and collector members due to the low electrical resistance and high thermal conductivity of materials like aluminum and copper, leading to high energy requirements and complex manufacturing equipment, which complicates the process of reducing internal resistance and ensuring consistent welding strength.
Innovation Solution
The battery design splits the substrate exposed portions into two groups, with a resin-based intermediate member holding connecting conductive members positioned between them, allowing for resistance welding between the substrate exposed portions and collector members in a single operation, thereby stabilizing the welds and reducing resistance variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resistance welding is used to join aluminum or copper substrate exposed portions to collector members, then welding strength is improved, but the high thermal conductivity of these materials requires extremely large energy input making the process impractical
Solution Approach 1:
The substrate exposed portions are divided into two separate groups (first and second groups) positioned on opposite sides of the electrode assembly. This segmentation allows independent welding operations on each group, enabling better heat management and reducing the total energy required compared to welding all portions simultaneously.
Solution Approach 2:
Collector members are positioned on both outer sides of the substrate exposed portions to serve as intermediary welding surfaces. This intermediary structure distributes the welding heat and allows for more efficient energy transfer, reducing the extremely large energy input that would otherwise be required to weld aluminum or copper substrates directly.
2Productivity
If substrate exposed portions are welded to collector members in a single operation, then productivity is improved, but welding quality becomes inconsistent due to the large number of stacked portions
Solution Approach 1:
By dividing the substrate exposed portions into two manageable groups and positioning collector members on both sides, the welding process is segmented into more controlled operations. This maintains high productivity through batch processing while improving welding quality consistency by reducing the complexity of each individual welding operation.
Solution Approach 2:
The invention combines multiple welding operations into a single integrated process by positioning collector members on both outer sides and welding simultaneously or in sequence. This merging approach maintains high productivity while the structured arrangement ensures consistent welding quality across all substrate portions.
3Quantity of substance
If the number of stacked substrate exposed portions is increased to achieve large battery capacity, then battery capacity is improved, but the complexity of welding operations increases making it difficult to ensure consistent welding strength
Solution Approach 1:
The large number of substrate exposed portions are segmented into two groups positioned on opposite sides of the electrode assembly. This segmentation simplifies the welding operation complexity by creating two manageable welding zones rather than attempting to weld all portions in a single complex operation, while still achieving the required large battery capacity.
4Reliability
If aluminum or copper materials are used for substrate and collector members to achieve low electrical resistance, then electrical conductivity is improved, but thermal conductivity becomes excessively high requiring complex manufacturing equipment
Solution Approach 1:
Segmenting the substrate exposed portions into two groups allows for optimized welding parameters and equipment design that can handle the high thermal conductivity of aluminum or copper materials without requiring excessively complex manufacturing equipment. The segmented approach enables better heat management during welding operations.
Solution Approach 2:
The collector members serve as intermediary components that facilitate welding of aluminum or copper substrate portions. This intermediary structure helps manage the high thermal conductivity challenge by providing dedicated welding surfaces that can be optimized for these materials, reducing the complexity of the overall manufacturing equipment required.
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 results in a prismatic sealed secondary battery with enhanced resistance weld quality, improved output, and reduced output variation, while simplifying the manufacturing process and ensuring reliable electrical connections.
Implementation Method 1
resistance welding between the substrate exposed portions and collector members
Data Source
Figure 1A~1C
Figure 2A~2D
Figure 3
AI summary
A prismatic sealed secondary battery according to an embodiment of the present invention includes an electrode assembly having stacked or wound positive and negative electrode substrate exposed portions and a pair of collector members electrically joined to the respective electrode substrate exposed portions. At least one of the electrode substrate exposed portions is split into two groups, and therebetween is disposed an intermediate member made of resin material and holding a plurality of connective conducting members. The collector member for the substrate exposed portions split into two groups is disposed on at least one of the outermost faces of the substrate exposed portions, and is electrically joined by a resistance welding method to the substrate exposed portions, together with the connecting conductive members of the intermediate member. This configuration lowers resistance of the electrode substrate exposed portions and the collector members and curbs variation in the welding strength.