Sealed Battery Lid Bonding for Stability
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Solution Overview
Problem
The existing structure of sealed secondary batteries, particularly those used in vehicles, faces challenges with structural stability and current collecting efficiency during high-rate charging and discharging, especially when subjected to vibrations, and there is a need for improved safety features to manage gases generated by abnormal conditions.
Innovation Solution
A sealed secondary battery design with a laminated electrode body where current collector exposed portions are bonded to the lid, minimizing internal resistance and preventing electrode shaking, and using a separator with adhesive to enhance stability, while positioning bonding portions close to the lid to act as barriers for gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a laminated electrode body structure is used to increase battery capacity per unit volume, then the battery capacity increases, but the structural stability decreases making the electrode body prone to shaking during vehicle operation
Solution Approach 1:
The patent applies preliminary action by pre-arranging spacers and holding tapes on the electrode body before sealing it in the case. The spacers are attached to the case inner wall in advance to define the electrode body's position, and holding tapes are prepared to secure the electrode body layers, preventing shaking during vehicle operation while maintaining the high-capacity laminated structure.
Solution Approach 2:
The patent uses spacers and holding tapes as intermediary elements between the electrode body and the case. These intermediaries fill gaps, maintain proper spacing, and secure the electrode body structure, thereby improving stability without compromising the battery's capacity density.
2Stability of the object's composition
If a holding tape is attached to cover the lamination surface to minimize positional deviation, then the structural stability improves, but the device complexity increases
Solution Approach 1:
The patent applies partial action by using holding tapes only at critical locations where positional deviation is most likely to occur, rather than covering the entire lamination surface. This selective application maintains necessary stability while minimizing the added complexity and material usage.
3Productivity
If current collection tabs are superimposed and connected to current collector terminals, then the current collecting efficiency improves, but the internal resistance increases during high-rate charging and discharging
Solution Approach 1:
The patent transitions from point-contact current collection (tabs) to surface-contact current collection by bonding the entire exposed portion of the current collector to the lid. This dimensional change from 0D/1D contact to 2D contact significantly reduces contact resistance and improves current collection efficiency, enabling high-rate charging and discharging with lower internal resistance.
4Object-affected harmful factors
If bonding portions are positioned close to the lid to act as barriers for gas flow, then the safety improves by preventing gas accumulation, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-defining the bonding position area on the lid before assembly. The bonding portions are positioned at predetermined locations close to the lid, which serves as a barrier to gas flow. This pre-planned positioning simplifies the manufacturing process by providing clear guidelines for bonding operations, reducing the actual precision requirements during assembly.
Data Source
Figure 1
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AI summary
In a secondary battery, a positive electrode current collecting portion (32) and a negative electrode current collecting portion (36) are bonded with a part of a positive electrode current collector exposed portion (52A) and a part of a negative electrode current collector exposed portion (56A) of a laminated electrode body (50), respectively. A bonding portion (Wp) between the positive electrode current collecting portion (32) and the positive electrode current collector exposed portion (52A), and a bonding portion (Wn) between the negative electrode current collecting portion (36) and the negative electrode current collector exposed portion (56A) are formed at positions at which, when the full length in a short side direction of each of the current collector exposed portions (52A, 56A) of the positive electrode (51) and the negative electrode (55) is set as L, a distance (P) from the end close to the lid (16) in the short side direction is less than L/2.