Flat Wound Battery Electrode Enfold Structure for Pressure Stability
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Solution Overview
Problem
Conventional flat wound electrode batteries face issues with uneven electrode reaction due to difficulty in maintaining appropriate surface pressure, leading to shortened battery life in cycle endurance.
Innovation Solution
A battery configuration where the first electrode sheet is wound to enfold the winding end portion of the second electrode sheet, allowing the winding end portion to pass through either straight or rounded portions, ensuring a stable and uniform surface pressure is maintained, even during expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a tape that prevents unwinding is attached on the outermost periphery of the wound electrode body, then the wound electrode body can be prevented from unwinding, but the surface pressure cannot be maintained and the winding end portions become loose during charging
Solution Approach 1:
The patent introduces a pressing member as an intermediary component between the wound electrode body and the battery case. This pressing member applies uniform pressure to the entire surface of the wound electrode body, including the winding end portions, thereby maintaining surface pressure during charging and discharging cycles without interfering with the electrode structure itself
Solution Approach 2:
The pressing member acts as a counterbalancing force against the expansion of the wound electrode body during charging. By applying continuous compressive force, it counteracts the loosening effect that would otherwise occur at the winding end portions, maintaining uniform surface pressure throughout the battery's operation
2Volume of moving object
If the winding end portions are disposed in the same curvature portion, then the structure is compact, but the electrode reaction becomes uneven and battery life is shortened
Solution Approach 1:
The patent applies different spatial arrangements to different components: winding end portions of the same electrode sheet are disposed at different locations (one in a curvature portion, the other in a flat portion), creating local variation in pressure distribution. This ensures uniform electrode reaction across different regions while maintaining compact overall structure
Solution Approach 2:
The patent changes the spatial parameters of winding end portion disposal from a symmetric configuration (both in curvature portions) to an asymmetric configuration (one in curvature portion, one in flat portion). This parameter change optimizes both compactness and uniformity of electrode reaction, preventing premature battery failure
Data Source
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AI summary
A battery (100) includes a flat wound electrode body (10) that is obtained by winding a first electrode sheet (20) and a second electrode sheet (30) in a flat shape via separator sheets (40a, 40b). The first electrode sheet (20) is disposed in the flat wound electrode body (10) so as to be wound on the outer peripheral side with respect to the second electrode sheet (30). The first electrode sheet (20) is wound so as to enfold a winding end portion (38) of the second electrode sheet (30). A winding end portion (28) of the first electrode sheet (20) is disposed so as to pass either of the straight portions (12a, 12b) or rounded portions (14a, 14b) where the winding end portion (38) of the second electrode sheet (30) is disposed and reach the next straight portion (12a, 12b) or pass through the next straight portion.