Composite Battery Substrate With Roughness-Tuned Tab Bonding
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high adhesive force and low contact resistance between the tab and the metal layers, which affects the overall performance and efficiency of the battery.
Innovation Solution
A composite substrate is designed with a support layer and metal layers having specific surface roughness ratios, where the first region attached to the tab has a higher roughness than the second region, enhancing adhesive force and reducing contact resistance through increased welding strength and contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface roughness of the metal layer is increased to improve adhesive force with the tab, then the contact resistance decreases, but the manufacturing complexity increases due to the need for selective roughness control in different regions
Solution Approach 1:
The metal layer is designed with different surface roughness characteristics in different regions: the first region (where the tab is attached) has a higher surface roughness to enhance adhesive force, while the second region has a lower surface roughness. This local differentiation resolves the contradiction by providing high adhesive force only where needed without uniformly increasing complexity across the entire metal layer.
Solution Approach 2:
The metal layer is segmented into at least two distinct regions with different surface roughness properties. The first region is specifically engineered with higher roughness for tab attachment, while the second region maintains lower roughness. This segmentation allows independent optimization of each region's surface characteristics to meet specific functional requirements.
2Reliability
If the surface roughness ratio between the first region and second region is increased to reduce contact resistance, then the welding strength improves, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a quantitative parameter range for the surface roughness ratio (Rz1/Rz2) between the first and second regions, where Rz1 is the average surface roughness of the first region and Rz2 is the average surface roughness of the second region. By defining this ratio parameter within specific bounds, the invention reduces contact resistance and improves welding strength while providing clear manufacturing targets that balance precision requirements.
Data Source
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AI summary
Disclosed are composite substrates and rechargeable lithium batteries. The composite substrate includes a support layer, a first metal layer on a top surface of the support layer, and a second metal layer on a bottom surface of the support layer. At least one of the first metal layer and the second metal layer includes a first region to which a tab is configured to be attached, and a second region different from the first region. A ratio of surface roughness of the first region to surface roughness of the second region is in a range of 3.5 to 7.