Flat Wound Electrode Assembly Layout for Small Roll Diameter
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Solution Overview
Problem
Existing wound electrode assemblies face challenges in achieving a small roll diameter while maintaining a flat shape, as the tips of the separators tend to overlap or fold during the shaping process, leading to increased thickness dimensions.
Innovation Solution
The solution involves using two separators with a thickness of 20 μm or less and a rigidity index of 18 mm or more, inserted from opposite directions during the winding process, and ensuring a clearance distance between their start edges to prevent overlap and folding, allowing for consistent production of wound electrode assemblies with a small roll diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the core diameter is decreased to make the roll diameter small, then the roll diameter is reduced, but the separator tips overlap or fold during the shaping process, leading to increased thickness dimensions
Solution Approach 1:
The separator is divided into two separate separators (first separator and second separator) with distinct winding start edges. This segmentation allows each separator to be positioned independently, preventing overlap and folding at the center of the wound electrode assembly, thereby enabling small roll diameter while maintaining manufacturing precision.
Solution Approach 2:
The first separator and second separator are positioned asymmetrically with respect to the winding axis, with their winding start edges located at different positions. This asymmetric arrangement ensures that the separator tips do not overlap during the shaping process, solving the contradiction between small roll diameter and positioning accuracy.
2Manufacturing precision
If two separators are used to prevent overlap, then the separator positioning accuracy is improved, but the device complexity increases
Solution Approach 1:
The first separator and second separator are combined in a symmetric arrangement around the winding axis, with their start edges positioned to face each other. This merging approach achieves precise separator positioning while maintaining structural symmetry, thereby reducing the perceived complexity of the device.
3Length of stationary object
If the separator thickness is reduced to 20 μm or less, then the thickness dimension is reduced, but the separator rigidity decreases, making it more prone to folding
Solution Approach 1:
The use of two separators with thickness of 20 μm or less creates a composite structure that achieves both reduced overall thickness and maintained rigidity. The dual-separator configuration provides structural support while keeping the individual separator layers thin, resolving the contradiction between thickness reduction and rigidity maintenance.
Data Source
AI summary
A battery includes a wound electrode assembly. The wound electrode assembly has a flat shape. The wound electrode assembly includes a first separator, a positive electrode plate, a second separator, and a negative electrode plate. The first separator, the positive electrode plate, the second separator, and the negative electrode plate are stacked in this order and then wound spirally. In a cross section perpendicular to a winding axis of the wound electrode assembly, the first separator has a first winding start edge inside an innermost circumference of the wound electrode assembly; the second separator has a second winding start edge inside the innermost circumference of the wound electrode assembly; the first winding start edge faces the second winding start edge with the winding axis interposed therebetween; and the first winding start edge is located apart from the second winding start edge.