Secondary Battery Sub-Tab Design 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 sub-tabs coupled to the electrode tabs of the electrode assemblies, which are bent to connect with current collectors, reducing defects and enhancing welding stability by minimizing internal space loss and increasing battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the current collector is made larger to increase battery capacity, then the battery capacity increases, but the welding quality deteriorates due to larger uncoated portions
Solution Approach 1:
The patent divides the connection structure into multiple segments: electrode tabs, sub-tabs, and current collectors. The sub-tabs act as intermediate connection elements that segment the welding process, allowing smaller, more reliable welds between sub-tabs and electrode tabs, while the current collector provides the main electrical connection. This segmentation resolves the contradiction by enabling large battery capacity through multiple parallel connections while maintaining welding quality through smaller, controlled weld joints.
2Quantity of substance
If the current collector is made larger to increase battery capacity, then the battery capacity increases, but defects in uncoated portions increase
Solution Approach 1:
The patent applies local quality by creating a recessed region in the current collector where the uncoated portion is concentrated. This recessed region has different geometric properties (smaller cross-sectional area) compared to the main body of the current collector. By localizing the uncoated portion connection in this recessed area, the patent enables precise control of the connection quality while the rest of the current collector maintains its full size for high battery capacity.
3Reliability
If sub-tabs are added to improve welding quality and reduce defects, then welding quality improves, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the sub-tabs structure. The sub-tabs serve as both mechanical connectors (providing structural support and alignment) and electrical conductors (transmitting current). By combining these functions into a single integrated component, the patent improves welding quality without proportionally increasing complexity, as the sub-tabs are simple elongated structures that perform multiple roles simultaneously.
Data Source
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.