Battery Electrode Sheet Curl Reduction via Drawn Uncoated Regions
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Solution Overview
Problem
Electrode sheets for batteries often curl during manufacturing, leading to skewed takeup and misalignment issues during winding, due to differences in elongation between coated and uncoated regions, which can cause wrinkling and tearing when tension is applied.
Innovation Solution
Creating drawn regions in the uncoated areas of the electrode sheet using an intermittent roll press alleviates strain, allowing for reduced curl and improved handling during winding by distributing tension perpendicular to the sheet's long direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the active material layer is subjected to working by rolling to improve coating quality, then the coating density and uniformity are improved, but the uncoated edge regions are not subjected to working, causing different elongation between coated and uncoated regions which leads to curling
Solution Approach 1:
The invention applies different processing treatments to different regions of the electrode sheet. The coated central region undergoes working by rolling while the uncoated edge regions undergo working by drawing. This local differentiation resolves the contradiction by ensuring each region is processed according to its specific characteristics, preventing curling while maintaining coating quality.
Solution Approach 2:
The invention divides the electrode sheet into two distinct regions for differential processing: the coated central region and the uncoated edge regions. By segmenting the processing approach, the patent addresses the different elongation characteristics of each region, with the uncoated regions undergoing additional drawing treatment to match the elongation of coated regions, thereby eliminating curling.
2Stability of the object's composition
If tension is applied to the electrode sheet to prevent curling during handling, then curling is suppressed, but wrinkling and tearing occur particularly in the uncoated regions due to the elongation difference
Solution Approach 1:
The invention performs working by drawing on the uncoated edge regions before the final assembly process. This preliminary action pre-establishes the appropriate elongation and dimensional stability in the uncoated regions, so that when the electrode sheet is subsequently handled and wound, the uncoated regions have already been prepared to match the coated regions' dimensions, preventing both curling and damage.
3Shape
If the uncoated regions are subjected to working by rolling to reduce elongation difference, then curling is reduced, but misalignment occurs during pressing making it impossible to subject prescribed locations to working
Solution Approach 1:
Instead of applying working by rolling to the uncoated regions (which would cause misalignment), the invention inverts the approach by applying working by drawing specifically to the uncoated edge regions. This inverted processing strategy targets the specific problem area without affecting the alignment of the coated regions, thereby reducing curling while maintaining positional accuracy.
4Strength
If a small load is applied during working by the press to avoid wrinkling, then less damage occurs, but the curl magnitude is not reduced and wrinkling still occurs in the long direction of the uncoated region
Solution Approach 1:
The invention changes the processing parameters by applying working by drawing to the uncoated regions, which fundamentally alters the dimensional characteristics of these areas. This parameter change in the uncoated regions' pre-processing state enables subsequent pressing to be performed with appropriate loads without causing curling or damage, as the uncoated regions have already been adjusted to match the coated regions' elongation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces curl magnitude, minimizes wrinkling and tearing, and enables high-speed manufacturing without increasing manufacturing operations, ensuring proper positional accuracy and alignment during battery assembly.
Implementation Method 1
Creating drawn regions in the uncoated areas of the electrode sheet using an intermittent roll press alleviates strain
Implementation Method 2
distributing tension perpendicular to the sheet's long direction
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Embodiments of the present invention provide such things as an electrode sheet having little curl for a spiral wound battery and a manufacturing method therefor. An electrode sheet is such that active material layer(s) is/are present and has/have been subjected to working by rolling at entire surface(s) thereof, except for at least one uncoated region U, of electrode sheet(s) comprising sheet(s) of metal foil(s) S. Moreover, drawn region(s) is/are provided at region(s) uncoated with active material layer(s) in such uncoated region(s) U. By thus creating drawn region(s) at uncoated region(s) of the electrode sheet, curling of the electrode sheet is suppressed, and furthermore, when tension is applied to carry out winding of the electrode sheet and/or convey the electrode sheet to subsequent operation(s), there is reduced likelihood of occurrence of wrinkling and/or tearing in the long direction of the electrode sheet.