Secondary Battery Collector Terminal With Deformable Lead Section
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Solution Overview
Problem
Conventional secondary batteries for hybrid and electric vehicles face issues with warpage deformation of the sealing member due to external forces applied during the bonding of the electrode body and current-collector terminal, which cannot be effectively suppressed even with increased rigidity of the current-collector terminal.
Innovation Solution
The secondary battery design incorporates a current collector terminal with an easily-deformable portion that absorbs external forces without melting, allowing the lead lower end portion to displace in the long-side direction of the sealing member and thereby reducing warpage deformation. This design includes a base adjoining portion and a lead upper end portion with specific deformable features such as thinned, curved, or reduced-width portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rigidity of the current-collector terminal is increased to reduce deformation, then the deformation of the current-collector terminal is reduced, but the rigidity of the sealing member is generally lower than the rigidity of the current-collector terminal, so the external force acting on each current-collector terminal is transmitted substantially directly to the sealing member, resulting in warpage deformation of the sealing member
Solution Approach 1:
The current-collector terminal is segmented into multiple functional portions: a base portion joined to the sealing member, a base adjoining portion, and a lead portion with a lead lower end portion bonded to the electrode body. This segmentation allows different portions to perform different functions, with the base adjoining portion or lead upper end portion designed as easily-deformable to absorb external forces before they reach the sealing member.
Solution Approach 2:
The easily-deformable portion is created by locally modifying the base adjoining portion or lead upper end portion through thinning, curving, or reducing width. This local quality change creates a specific region with reduced rigidity that preferentially deforms under external force, protecting the sealing member from warpage while maintaining overall structural integrity.
2Reliability
If a current cutoff mechanism with a reduced cross-section portion is used to prevent excessive temperature rise, then the battery is protected from over-charge or over-discharge, but the reduced cross-section portion melts due to temperature rise, causing the battery to be unusable without replacing the current-collector terminal
Solution Approach 1:
The material properties of the easily-deformable portion are specifically selected and designed to have a deformation temperature that is lower than the melting point but higher than normal operating temperatures. This parameter change allows the portion to deform and absorb external forces during normal operation and during thermal events, preventing both warpage deformation and catastrophic melting that would render the battery unusable.
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 solution effectively suppresses warpage deformation of the sealing member, ensuring accurate temperature measurement by the sensor and preventing damage to the battery components during external force application.
Implementation Method 1
either the base adjoining portion or the lead upper end portion is provided with an easily-deformable portion formed to be deformable with respect to the base portion without melting, to allow the lead lower end portion to be displaced in the long-side direction of the sealing member
Data Source
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AI summary
A secondary battery (10) includes a case body (11), a sealing member (12) closing the case body (11), an electrode body (2) housed in the case body (11) and constituted of positive and negative electrode bodies (21, 22) stacked with separators (23) interposed therebetween, and positive and negative collector terminals (4) each including a base portion (41) located in end portions of the sealing member (12) and connected thereto via an insulating member (3), a base adjoining portion (42) adjacent to the base portion (41), separated from or separably in contact with the insulating member (3), and a lead portion (43) with a lead upper end portion (43a) connected to the base adjoining portion (42) and a lead lower end portion (43b) bonded to the electrode body (2). The base adjoining portion (42) or the lead upper end portion (43a) includes an easily-deformable portion (44) that can be deformed without melting with respect to the base portion (41) to allow displacement of the lead lower end portion (43b) in the long-side direction of the sealing member (12).