Cylindrical Battery Electrode Assembly for Stable Tab-Less Welding
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Solution Overview
Problem
Conventional cylindrical battery cells with strip-shaped electrode tabs experience high resistance, heat generation, and poor current collection efficiency due to concentrated current flow, and tab-less designs face issues with uncoated portions unfolding during winding, leading to irregular shapes and degraded welding quality.
Innovation Solution
The electrode assembly incorporates cutting and cross-cutting portions in the uncoated regions of electrodes, forming T or + shapes, to stabilize the bent portions and enhance welding quality by ensuring uniform flattening and increased contact area with current collecting plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a strip-shaped electrode tab is used in conventional cylindrical battery cells, then the structure is simple and easy to manufacture, but current is concentrated on the tab causing high resistance, high heat generation, and poor current collection efficiency
Solution Approach 1:
The uncoated portion of the electrode is divided into multiple segments by forming cutting portions and cross-cutting portions. This segmentation creates multiple contact points with the current collecting plate, distributing the current flow and improving current collection efficiency while maintaining manufacturing simplicity
Solution Approach 2:
The electrode uncoated portion is transformed from a flat strip shape to a three-dimensional structure with cutting portions and cross-cutting portions that extend in multiple directions. This dimensional change increases the contact area with the current collecting plate without complicating the manufacturing process
2Area of stationary object
If the uncoated portion is bent to increase welding area in tab-less battery cells, then the contact area with current collecting plate increases, but the bent portion unfolds again during winding causing irregular shapes and degraded welding quality
Solution Approach 1:
Cutting portions and cross-cutting portions are formed in advance on the electrode uncoated portion before the winding process. This preliminary action creates a structure that maintains its shape during winding, preventing the uncoated portion from unfolding and ensuring stable welding area without requiring post-winding flattening
Solution Approach 2:
The cutting portions and cross-cutting portions are strategically positioned at specific locations on the electrode uncoated portion. This local modification creates areas of controlled flexibility and rigidity, allowing the structure to maintain its shape during winding while still providing increased contact area for welding
3Manufacturing precision
If the bent uncoated portion is flattened uniformly after winding, then welding quality may be improved, but the process complexity increases and stability deteriorates due to difficulty in maintaining uniform shape
Solution Approach 1:
The cutting portions and cross-cutting portions are formed before winding, creating a pre-structured electrode uncoated portion that naturally maintains its shape during the winding process. This eliminates the need for complex post-winding flattening operations, reducing process complexity while ensuring consistent welding quality
Data Source
AI summary
An embodiment of the present disclosure can provide an electrode assembly, comprising: a first electrode wound about a winding axis and comprising a first uncoated portion a second electrode wound about the winding axis and comprising a second uncoated portion, and a separator disposed between the first electrode and the second electrode; wherein the first uncoated portion comprises a plurality of cutting portions, formed at a predetermined depth from an end of the first electrode, and a plurality of cross-cutting portions, extending from the cutting portions and formed in a winding direction.