Wound Electrode Assembly With Outward-Bent Tabs to Prevent Short Circuits
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Solution Overview
Problem
Cylindrical secondary batteries face limitations in increasing capacity and output due to resistance issues caused by the physical distance of conductive tabs, and existing methods to address this can result in short circuits when non-coated electrode portions are folded inward.
Innovation Solution
The electrode assembly features a non-coated portion of the electrode current collector bent multiple times toward the outer periphery, with segmental pieces that can be bent twice to face the lateral surface, preventing contact with the negative electrode and thus avoiding short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-coated electrode portions are folded inward to create tabs, then conductive path efficiency is improved, but short circuit risk increases due to contact with the negative electrode
Solution Approach 1:
Instead of folding the non-coated electrode portion inward toward the center (conventional method), the patent folds it outward toward the outer periphery of the wound structure. This inversion of the folding direction prevents the positive electrode tab from contacting the negative electrode, eliminating the short circuit risk while maintaining conductive efficiency
Solution Approach 2:
The separator acts as an intermediary barrier between the positive and negative electrodes. By positioning the folded non-coated portion of the positive electrode against the separator rather than allowing direct contact with the negative electrode, the separator mediates and prevents potential short circuits
2Quantity of substance
If electrode thickness and separator thickness are increased to accommodate more electrodes, then battery capacity increases, but resistance increases due to greater physical distance from tabs
Solution Approach 1:
The patent creates a local quality difference by having non-coated portions (tabs) at specific locations on the electrode. These localized conductive paths provide low-resistance connections at critical points, allowing the rest of the electrode to be thicker for increased capacity without uniformly increasing resistance throughout the entire structure
3Reliability
If non-coated portions are made longer to improve conductivity, then resistance decreases, but short circuit risk increases due to greater likelihood of contact with negative electrode
Solution Approach 1:
The patent inverts the folding direction of the non-coated portion, extending it outward toward the outer periphery rather than inward toward the center. This allows the non-coated portion to be longer for better conductivity while the outward folding direction prevents contact with the negative electrode, eliminating the short circuit risk
Data Source
AI summary
An electrode assembly is made by stacking and winding a first electrode, a separator, and a second electrode, in which the first electrode includes a current collector, and an electrode active material layer provided on the current collector, in which an edge portion of the current collector provided at one end of a winding axis of the electrode assembly includes a non-coated portion on which no electrode active material layer is provided, and in which a non-coated portion of the first electrode is bent one or more times in a direction from a winding center of an electrode assembly toward an outer periphery of the electrode assembly.