Secondary Battery Current Collector Segmentation for Welding Quality
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Solution Overview
Problem
Secondary batteries face defects in uncoated portions of current collectors, which affect capacity and welding quality, leading to inefficiencies in charging and discharging operations.
Innovation Solution
The design incorporates a series of electrode assemblies with sub-tabs that are bent to contact the current collectors, reducing internal space loss and enhancing electrical connections, thereby improving the welding quality and capacity by minimizing defects and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the current collector is made larger to increase battery capacity, then the capacity is improved, but the welding quality deteriorates due to increased defects in uncoated portions
Solution Approach 1:
The current collector is divided into multiple regions: a first region with a larger area for increasing battery capacity, and a second region inwardly recessed relative to the first region. This segmentation allows the larger first region to provide increased capacity while the recessed second region reduces the uncoated portion area, thereby minimizing defects and maintaining welding quality.
2Quantity of substance
If the electrode assembly thickness is reduced to increase energy density, then the energy density is improved, but the welding quality deteriorates due to defects in uncoated portions
Solution Approach 1:
The current collector is segmented into a first region and a second region inwardly recessed relative to the first region. This allows the electrode assembly to be thinner for increased energy density while the recessed second region minimizes uncoated portion defects, maintaining welding quality despite the reduced thickness.
3Reliability
If the uncoated portion area is reduced to improve welding quality, then the welding quality is improved, but the battery capacity deteriorates due to less active material coverage
Solution Approach 1:
The current collector is divided into a first region with larger area for battery capacity and a second region inwardly recessed relative to the first region. The recessed second region reduces the uncoated portion area to improve welding quality, while the larger first region maintains adequate active material coverage for battery capacity.
Solution Approach 2:
Different regions of the current collector are given different properties: the first region has a larger area optimized for battery capacity, while the second region is inwardly recessed to minimize uncoated portion defects and improve welding quality. This local differentiation allows both objectives to be achieved simultaneously.
Data Source
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AI summary
Provided is a secondary battery, which can reduce defects of an uncoated portion of a current collector while ensuring a larger capacity and improving welding quality of the current collector. In one embodiment, the secondary battery includes a series of electrode assemblies each including a first electrode tab and a second electrode tab, a case accommodating the electrode assemblies, a cap plate coupled to the case at an opening in the case, a first current collector electrically connected to the first electrode tabs of the electrode assemblies, a second current collector electrically connected to the second electrode tabs of the electrode assemblies, and a first series of sub-tabs. A first sub-tab is coupled to the first electrode tab of a first electrode assembly, and a second sub-tab is coupled to the first electrode tab of a second electrode assembly. The first sub-tab is bent along a first boundary and the second sub-tab is bent along a second boundary.