Wound Secondary Battery Electrode Layout for Low-Resistance Welding
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Solution Overview
Problem
Conventional battery technology faces issues with high internal resistance due to dense welding points at the center, leading to incomplete foil overlap and assembly challenges, particularly during high-rate discharge.
Innovation Solution
A secondary battery design with a wound structure featuring positive and negative electrodes, where non-covered parts of the electrodes are bent and overlapped to facilitate reliable welding, reducing internal resistance through multiple points of contact with current-collecting plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If welding points are denser toward the center to collect current from the whole wound foil ends, then current collection is improved, but internal resistance increases and welding reliability deteriorates
Solution Approach 1:
The electrode foil ends are segmented into multiple separate ends instead of being collected at a single central point. The positive electrode has first and second ends, and the negative electrode has third and fourth ends, which are positioned at different locations along the exterior can. This segmentation distributes the current collection points, preventing the density issue at the center while maintaining efficient current collection from the entire wound structure.
Solution Approach 2:
The current collection structure transitions from a single-point central collection to a distributed multi-dimensional arrangement along the exterior can. The electrode ends are arranged in different spatial positions (first end, second end, third end, fourth end) rather than converging at one location, effectively using the longitudinal dimension of the can to distribute welding points and reduce local density.
2Ease of manufacture
If the foil is folded from the outer periphery toward the central part, then assembly is simplified, but the central space is blocked and welding cannot be achieved
Solution Approach 1:
Instead of folding the foil from the outer periphery toward the center (convergent folding), the patent inverts the approach by positioning electrode ends at multiple locations along the can without requiring them to converge at the center. The winding structure maintains its form, but the electrode ends are accessed at different positions, eliminating the need for central space clearance while still achieving proper assembly.
3Power
If high-rate discharge is implemented to achieve high power, then power output is improved, but internal resistance increases due to large current flow
Solution Approach 1:
The current collection is segmented into multiple parallel paths through the distributed electrode ends (first, second, third, and fourth ends). This segmentation creates multiple current flow channels, effectively reducing the internal resistance for high-rate discharge by distributing the large current across multiple parallel conduction paths rather than forcing it through a single central point.
Data Source
AI summary
Provided is a secondary battery, where a positive electrode includes a first covered part covered with a positive electrode active material layer and a positive electrode active material non-covered part on a positive electrode foil, and a negative electrode includes a second covered part covered with a negative electrode active material layer and a negative electrode active material non-covered part on a negative electrode foil, the positive electrode active material non-covered part is joined to the positive electrode current-collecting plate at one end of an electrode wound body, and the negative electrode active material non-covered part is joined to the negative electrode current-collecting plate at the other end of the electrode wound body.