Secondary Battery Tab Bonding Structure for Deformation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries face deformation issues due to nonuniform expansion stress caused by sharp differences in thickness between the active material film coating and the adjacent substrate after tab welding, leading to performance risks.
Innovation Solution
A secondary battery design featuring a housing, electrode assembly, and bonding pieces with strategically placed grooves and filling portions to reduce thickness differences and improve uniformity, using materials with specific melting temperatures and Rockwell hardness for enhanced flexibility and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the active material film coating is removed by a specified amount at the tab weld joint to allow welding tolerance, then the tab welding process becomes easier, but the thickness difference between the exposed substrate and adjacent region increases sharply, leading to nonuniform expansion stress and battery deformation
Solution Approach 1:
The bonding piece is designed with different regions having different functions: a first region for filling the exposed substrate area and a second region for sealing the tab weld joint. This local differentiation allows the bonding piece to simultaneously address both the welding tolerance requirement and the thickness uniformity issue, preventing battery deformation while facilitating easy welding
Solution Approach 2:
The bonding piece acts as an intermediary component between the electrode assembly and the tab. It fills the exposed substrate area and provides a uniform bonding surface, mediating between the thickness difference caused by coating removal and the requirement for uniform expansion stress distribution during battery cycling
2Adaptability or versatility
If a universal MMT jelly-roll structure is used with tab welding tolerance, then the design is more adaptable and easier to manufacture, but the blank substrate exposed after coating removal causes nonuniform stress release during cycling
Solution Approach 1:
The bonding piece incorporates functionally differentiated regions: one for filling the exposed substrate and another for sealing the weld joint. This local quality differentiation maintains the universal MMT structure's adaptability while locally addressing the stress uniformity issue to ensure reliable cycle performance
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A secondary battery (1) includes a housing (11), an electrode assembly (12), a first tab (13), and a first bonding piece (14). The electrode assembly (12) is located in the housing (11). The electrode assembly (12) includes a first electrode plate (121). The first electrode plate (121) includes a first current collector (1211)and a first active material layer (1212). The first active material layer (1212) includes a first groove (12121) that exposes a first surface of the first current collector (1211). The exposed first surface includes a first region (12122) and a second region (12123). The first bonding piece (14) includes a first sealing portion (141) and a first filling portion (142) connected to each other. At least a part of the first sealing portion (141) is disposed between the second part (132) and the housing (11) to bond the second part (132) and the housing (11) together. When viewed along a thickness direction of the first electrode plate (121), the first filling portion (142) is located in the second region (12123). When the secondary battery (1) of this application is subjected to pressurized chemical formation and cycling, the risk of deformation of the battery is reduced.