Wound Electrode Core Structure to Prevent Separator Gaps
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Solution Overview
Problem
Conventional energy storage devices with flexible core materials are prone to gaps between electrode plates and separators, which can lead to short circuits due to conductive contaminants entering these gaps.
Innovation Solution
The energy storage device features a tubular core material with specific line parts and curved portions, where the electrode plate's inner peripheral edge is positioned outside the curved areas, preventing the edge from floating and reducing the risk of short circuits by ensuring proper alignment and tension distribution during the winding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a flexible core material is used in the power generating element, then the battery can be formed into a flat shape by pressing, but a gap may be generated between the electrode plate and separator due to inward curvature of the core material
Solution Approach 1:
The core material is designed with non-uniform thickness, having a first thickness in a first region and a second thickness different from the first thickness in a second region. This local variation in thickness compensates for the inward curvature of the flexible core material during pressing, preventing gap formation between the electrode plate and separator while maintaining the flat shape of the battery.
2Ease of manufacture
If the core material is highly flexible to allow pressing into flat shape, then manufacturing flexibility is improved, but the risk of short circuit due to contamination entering gaps increases
Solution Approach 1:
The core material employs local quality variation through non-uniform thickness distribution. The thicker region provides structural support to prevent gap formation in areas prone to inward curvature, thereby eliminating pathways for contamination entry while preserving the overall flexibility needed for pressing into flat shape.
3Reliability
If the core material thickness is increased to prevent gap formation, then reliability is improved, but the device complexity and material usage increase
Solution Approach 1:
Rather than uniformly increasing the core material thickness throughout, the invention applies local quality by varying the thickness only in specific regions where inward curvature occurs during pressing. This targeted approach prevents gap formation and maintains reliability while minimizing additional material usage and device complexity.
Data Source
AI summary
An energy storage device includes an electrode assembly having a negative electrode plate and a separator wound around a tubular core material. The core material has a first line part and a second line part extending along a first imaginary line and a second imaginary line parallel to a long side surface of a case, respectively. At least one of the first line part and the second line part has a curved portion that protrudes toward the other beyond the first imaginary line or the second imaginary line. An inner peripheral edge of the negative electrode plate is located at a position other than the curved portion in at least one of the first line part and the second line part.