Roll Press Friction Control for Electrode Wrinkle Prevention
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Solution Overview
Problem
During the roll press process of strip-shaped electrode sheets for lithium ion secondary batteries, oblique wrinkles frequently occur in the active-material absent portions due to uneven tension distribution, as these portions are thinner and less compressed than the active material portions, leading to reaction forces that cause wrinkles near the boundary between the two.
Innovation Solution
A roll press apparatus with a first press roll and a second press roll, where the second contact part has a larger frictional-force generating form than the first contact part, ensuring a higher frictional force is applied to the active-material absent portion, dispersing downstream tension and reducing reaction forces, thereby preventing oblique wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional roll press apparatus with uniform contact parts is used, then the active material layer can be compressed uniformly, but oblique wrinkles occur in the active-material absent portion due to uneven tension distribution
Solution Approach 1:
The first press roll is designed with different contact part configurations: a first contact part for the active material portion and a second contact part for the active-material absent portion. The second contact part has a larger frictional-force generating form, creating locally differentiated friction characteristics to match the different mechanical properties of the two regions, thereby preventing wrinkles in the thinner active-material absent portion
Solution Approach 2:
The frictional force parameter is changed locally by modifying the contact part structure. The second contact part is configured to generate a larger frictional force compared to the first contact part, adapting the press roll's interaction parameters to the specific needs of different electrode sheet regions during the compression process
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 increased frictional force between the second contact part and the active-material absent portion effectively disperses tension, preventing the generation of oblique wrinkles near the boundary with the active material portion, resulting in a smoother roll-pressed strip-shaped electrode sheet.
Implementation Method 1
the second contact part of the first press roll is configured, differently from the first contact part, to have a large frictional-force generating form that causes a larger frictional force to be generated between the second contact part and the active-material absent portion
Data Source
AI summary
A roll press apparatus includes a first press roll and a second press roll. The first press roll includes a first contact part configured to contact an active material portion of a strip-shaped electrode sheet and a second contact part configured to contact an active-material absent portion of the strip-shaped electrode sheet. The second contact part has a large frictional-force generating form that causes a larger frictional force to be generated between the second contact part and the active-material absent portion of the strip-shaped electrode sheet than an imaginary frictional force which would be generated if the active-material absent portion of the strip-shaped electrode sheet were made to contact the first contact part.