Wound Electrode Assembly Layout to Prevent Inner-Circle Collapse
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Solution Overview
Problem
The service life of electrochemical devices, such as batteries, is compromised due to the collapse of electrode plates within the inner winding circle, caused by inward radial pressure resulting from volume expansion during charging.
Innovation Solution
The electrochemical device incorporates a wound electrode assembly with a positive electrode plate where the positive electrode winding starting end is positioned close to the second reference line, forming a zero or acute angle (0°≤α≤30°) with the second reference line. This configuration enhances the structural stability of the electrode assembly, preventing collapse and improving the service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode plate undergoes volume expansion during charging, then the battery capacity is improved, but the inner winding circle experiences larger radial pressure causing electrode collapse
Solution Approach 1:
The patent applies asymmetry by positioning the positive electrode winding starting end at a specific angular location (0°≤α≤30° relative to the second reference line) rather than symmetrically. This asymmetric positioning ensures the starting end is located in a region with smaller curvature radius that can better withstand radial pressure during volume expansion, preventing collapse while maintaining battery capacity.
Solution Approach 2:
The patent applies local quality by creating different structural characteristics at different locations of the wound electrode assembly. The positive electrode winding starting end is specifically positioned in a region with different curvature properties (smaller radius) compared to other regions, allowing this local area to have enhanced pressure resistance while other regions maintain their functional properties.
2Quantity of substance
If the curvature of the inner winding circle is small, then the winding density is improved, but the required radius change for volume expansion is larger leading to greater radial pressure
Solution Approach 1:
The patent positions the positive electrode winding starting end asymmetrically at an angle of 0°≤α≤30° relative to the second reference line. This creates an asymmetric structure where the starting end is located in a region with smaller curvature radius that can better accommodate the larger radius change required during volume expansion, reducing radial pressure while maintaining overall winding density.
Solution Approach 2:
The patent changes the angular position parameter of the positive electrode winding starting end to be within 0°≤α≤30° relative to the second reference line. This parameter adjustment optimizes the location where the electrode plate experiences volume expansion, allowing the structure to better handle the stress from radius changes while maintaining winding density.
3Ease of manufacture
If the positive electrode winding starting end is positioned at the first reference line, then the manufacturing is simplified, but the electrode plate collapse failure occurs more easily
Solution Approach 1:
The patent deliberately introduces asymmetry by positioning the positive electrode winding starting end at an angle of 0°≤α≤30° relative to the second reference line rather than aligning it with the first reference line. This asymmetric positioning improves reliability by placing the starting end in a region better suited to withstand radial pressure, while the angular range remains narrow enough to maintain reasonable manufacturing precision.
Solution Approach 2:
The patent changes the angular position parameter from the conventional first reference line alignment to a new parameter range of 0°≤α≤30° relative to the second reference line. This parameter optimization balances manufacturing feasibility with improved structural reliability, preventing collapse while maintaining ease of manufacture within the specified angular tolerance.
Data Source
AI summary
An electrochemical device, including a wound electrode assembly; the electrode assembly has a winding centerline, the electrode assembly includes a positive electrode plate, and along a winding direction of the positive electrode plate, a positive electrode active material layer of the positive electrode plate has a positive electrode winding starting end and a positive electrode winding ending end. A straight line passing through the positive electrode winding ending end and orthogonal to the winding centerline is defined as a first reference line, a straight line orthogonal to the first reference line and orthogonal to the winding centerline is defined as a second reference line, and a straight line passing through the positive electrode winding starting end and orthogonal to the winding centerline is defined as a third reference line, where a zero or acute angle α exists between the third reference line and the second reference line, satisfying 0°≤α≤30°.