High-Density Electrode Thickness Zoning to Prevent Fat Edge Cracking
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Solution Overview
Problem
The manufacturing of high-density electrodes for lithium secondary batteries is hindered by the 'fat edge' phenomenon, leading to localized increases in electrode slurry loading, which causes surface contamination, rolling roll deterioration, and potential lithium precipitation, as well as electrode cracking during the rolling process.
Innovation Solution
The electrode design incorporates specific thickness profiles for the H1, H2, and H3 regions, with controlled thickness ratios (0.2≤h1/h2≤0.7 and h2/h3≥0.9) to prevent localized loading increases, ensuring even pressure distribution and reducing the risk of cracking and lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the overall side loading amount is reduced by improving the coating shim shape or adjusting the die-nozzle gap, then the fat edge phenomenon is reduced, but Li precipitation occurs due to inversion of the N/P ratio
Solution Approach 1:
The invention applies local quality by creating a thickness profile where the edge portion (within 5mm from the end) has reduced loading amount compared to the center portion. This localized adjustment prevents fat edge phenomenon at critical areas without globally reducing loading, thereby avoiding Li precipitation while maintaining manufacturing precision.
2Object-affected harmful factors
If the overall side loading amount is reduced to prevent fat edge phenomenon, then surface contamination and rolling roll deterioration are reduced, but electrode cracking occurs due to increased pressure on the side
Solution Approach 1:
The invention creates a localized thickness reduction only at the edge portion (within 5mm from the end) while maintaining normal thickness in the center. This local adjustment reduces surface contamination and rolling roll deterioration at critical edge areas without globally reducing loading, thereby preventing electrode cracking while still addressing harmful factors.
3Manufacturing precision
If the overall side loading amount is reduced to prevent fat edge phenomenon, then the thick edge and side ring are reduced, but Li precipitation occurs during charging and discharging
Solution Approach 1:
The invention implements local quality control by reducing the loading amount specifically in the edge portion (within 5mm from the end) while maintaining adequate loading in the center portion. This localized approach improves thickness uniformity at critical edge areas without globally reducing loading, thereby preventing Li precipitation during charging and discharging while still achieving manufacturing precision.
Data Source
AI summary
Provided is a high-density electrode and a method of manufacturing the same. An electrode for a secondary battery includes an electrode current collector, and an electrode active material layer formed on at least one surface of the electrode current collector. The electrode active material layer includes an H1 region, an H2 region and an H3 region sequentially provided from an end of the electrode active material layer toward a center. The H2 region includes an inclined section in which a thickness increases from the H1 region toward the H3 region, and the electrode satisfies the following formulas (1) and (2), 0.2≤h1/h2≤0.7 . . . (1), h2/h3≥0.9 . . . (2), where h1 is an average thickness of the H1 region, h2 is an average thickness of the H2 region, and h3 is an average thickness of the H3 region.