Roll Press Wrinkle Prevention for Lithium Battery Electrodes
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Solution Overview
Problem
Lithium ion battery electrode plates with coated and uncoated parts experience differential elongation during roll-pressing, leading to wrinkle formation and cracking due to the difference in thickness and stretching, which complicates the manufacturing process and affects the winding process.
Innovation Solution
A roll-press machine with a wrinkle occurrence prevention mechanism using a small diameter work roll and a larger diameter backup roll in a V-shape formation, where the work roll presses the uncoated part and the backup roll strengthens it, ensuring balanced elongation between the coated and uncoated parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the coated part and uncoated part are simultaneously pressed with pressing rolls, then the coated part is pinched and stretched, but the uncoated part is not pinched and does not stretch, causing differential elongation and wrinkle formation
Solution Approach 1:
The pressing system is segmented into two independent subsystems: one for the coated part and one for the uncoated part. Each subsystem has its own pressing rolls that can independently control the elongation of respective parts, preventing differential elongation and wrinkle formation while achieving uniform manufacturing precision.
2Manufacturing precision
If a dedicated processing roll with convex-concave steps is used to stretch the uncoated part, then the uncoated part can be elongated, but the metal foil may be holed or cracked due to its thinness (10 to 20 μm)
Solution Approach 1:
The pressing parameters are optimized by using cylindrical pressing rolls with controlled surface roughness and adjustable pressing forces. The pressing force is precisely controlled to be sufficient for elongation but not excessive to cause damage to the thin metal foil, achieving both elongation and integrity preservation through parameter optimization.
3Manufacturing precision
If the pressing rolls are positioned to press only the uncoated part, then the uncoated part can be stretched, but the coated part remains unpressed, creating imbalance in the electrode plate structure
Solution Approach 1:
The pressing system is divided into independent segments for coated and uncoated parts, each with its own pressing rolls. This segmentation allows simultaneous but independent pressing of both parts, maintaining structural balance while achieving the required elongation of the uncoated part.
4Strength
If the convex-concave steps on the processing roll are made fine to prevent holed or cracked metal foil, then the metal foil integrity is maintained, but the positions of convex-concave must accurately match between upper and lower rolls, increasing device complexity
Solution Approach 1:
Instead of using complex convex-concave stepped rolls requiring precise alignment, the invention employs simple cylindrical pressing rolls with controlled surface properties. These simpler rolls are easier to manufacture and install, reducing device complexity while still maintaining metal foil integrity through optimized pressing parameters.
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
This solution effectively prevents wrinkle formation and ensures balanced elongation, allowing for smooth processing and winding of the electrode plates without wrinkles, even with very thin metal foils, using a simple and cost-effective mechanism.
Implementation Method 1
the uncoated part is pressed to such one of pressing rolls
Implementation Method 2
a wrinkle occurrence prevention means provided with a work roll and a backup roll for strengthen the work roll
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
{ Summary} {Problem} Provided is a roll-press machine provided with a wrinkle occurrence prevention device for suppressing occurrence of wrinkles caused by a roll-pressing operation on a coated part and an uncoated part of an electrode plate, and a roll-pressing method. {Solution} A work roll having a diameter smaller than that of the pressing roll is pressed to allow the uncoated part to be rolled between the pressing roll and the work roll, and the work roll is held by two backup rolls arranged in a V-shape formation so that the work roll can press the uncoated part with a pressing force uniform in width-wise.