Prismatic Battery Sealing Plate Projection Weld
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Solution Overview
Problem
Prismatic secondary batteries used in electric and hybrid electric vehicles face reliability issues due to the vulnerability of the conductive path between the electrode body and the outside, which can break under strong impact or vibration, leading to potential internal short circuits.
Innovation Solution
A prismatic secondary battery design featuring a projection on the sealing plate that fits into a connection opening or notch in the current collector, with a weld nugget formed to ensure a strong and reliable connection, and a distribution of weld nugget density to prevent metal spatters and concentrate load along the boundary portion, enhancing the connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the positive-electrode current collector is connected to the sealing plate with a simple structure, then the number of components decreases, but the reliability of the conductive path under impact and vibration deteriorates
Solution Approach 1:
The connection structure is segmented into distinct functional elements: a projection protruding from the sealing plate, a connection opening in the current collector base, and a connection notch. This segmentation allows each element to perform its specific function while maintaining overall structural integrity under mechanical stress.
Solution Approach 2:
The projection is pre-formed on the sealing plate and the connection opening/notch is pre-formed in the current collector base before assembly. This preliminary preparation ensures proper alignment and facilitates reliable welding connection, preventing misalignment issues that could compromise conductive path reliability under impact.
2Strength
If the projection and base are welded with uniform weld nugget density, then the connection strength is consistent, but metal spatters are produced and load concentration occurs
Solution Approach 1:
The weld nugget density is made non-uniform with specific local characteristics: higher density regions are positioned at the boundary portion between the projection and base to concentrate load-bearing capacity where mechanical stress is highest, while lower density regions reduce metal spatter generation. This local differentiation optimizes both connection strength and harm reduction.
Solution Approach 2:
The welding parameters are changed spatially across the connection interface, creating varying weld nugget densities in different regions. This parameter variation allows the connection to achieve optimal strength-to-spatter ratio by concentrating welding energy where it is most needed for load bearing while reducing it where spatter is the primary concern.
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
The design significantly increases the reliability of the battery by preventing damage to the conductive path and reducing the risk of internal short circuits, while allowing for efficient manufacturing and increased volume energy density.
Implementation Method 1
The projection and the base are welded to each other, and a weld nugget is formed
Data Source
AI summary
A secondary battery includes an electrode body that includes a positive-electrode sheet and a negative-electrode sheet, a prismatic exterior body that accommodates the electrode body, a metallic sealing plate that seals an opening of the prismatic exterior body, and a positive-electrode current collector that is electrically connected to the positive-electrode sheet and the sealing plate. The positive-electrode current collector includes a base that faces the sealing plate and a lead that is disposed on an end portion of the base. A projection is formed on the sealing plate. The projection is fitted in a connection opening that is formed in the base. The projection and the base are welded to each other.