Battery Electrode Wettability Layout to Prevent Slurry Sliding
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Solution Overview
Problem
The formation of sliding portions at the ends of the active material layer in secondary battery electrodes leads to reduced capacity and unstable capacity balance between the positive and negative electrodes, due to the spreading of the active material slurry during coating, which results in Li precipitation and performance degradation.
Innovation Solution
The electrode is designed with a current collector having distinct surface portions with controlled contact angles for water droplets, where the first surface portion is treated to have a smaller contact angle than the second, and surface protrusions on the second portion act as dams to prevent slurry spreading, ensuring uniform coating and improved adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the active material slurry is coated on the current collector, then the active material layer is formed, but the slurry spreads out causing sliding portions with smaller thickness at the ends
Solution Approach 1:
The current collector surface is divided into different regions with different wettability characteristics. The central portion has high wettability (small contact angle) to promote slurry adhesion, while the side portions have low wettability (large contact angle) to prevent slurry spreading. This local differentiation of surface properties solves the sliding phenomenon by creating distinct functional zones on the same substrate.
Solution Approach 2:
The wettability parameter of the current collector surface is changed by applying a hydrophobic coating selectively to different regions. By controlling the contact angle parameter (10°-40° for central portion, 50°-90° for side portions), the slurry flow behavior is precisely controlled to eliminate the sliding phenomenon while maintaining uniform coating thickness.
2Manufacturing precision
If seam shapes are modified to increase slurry flow rate at side portions, then the sliding problem may be reduced, but swelling occurs
Solution Approach 1:
Instead of uniformly modifying the seam shape across the entire current collector, the invention applies local quality differentiation by creating hydrophobic side portions that specifically constrain slurry flow at the edges. This localized approach prevents swelling at the boundaries while maintaining proper slurry distribution in the central coating region.
3Reliability
If the sliding portion is not controlled, then the capacity balance between positive and negative electrodes reverses, but control mechanisms increase device complexity
Solution Approach 1:
The hydrophobic coating is applied to the current collector surface before the slurry coating process. This preliminary action creates predetermined wettability patterns that automatically guide slurry flow and prevent sliding during the subsequent coating operation, eliminating the need for complex real-time control mechanisms while ensuring stable capacity balance.
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 design reduces the sliding portion length by up to 30%, prevents Li precipitation, maintains capacity balance, and enhances cycling characteristics and adhesion strength, thereby improving the overall performance of the secondary battery.
Implementation Method 1
a contact angle of water droplet on the first surface portion is smaller than a contact angle of water droplet on the second surface portion
Data Source
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AI summary
Disclosed are an electrode with improved sliding portions, a method for manufacturing the same and a secondary battery including the same, the electrode including a current collector; and an active material layer located on at least one surface of the current collector, wherein the current collector has at least one first surface portion in contact with the active material layer, and a second surface portion located at two sides of the first surface portion, wherein the active material layer is not located at the second surface portion, and wherein a contact angle of water droplet on the first surface portion is smaller than a contact angle of water droplet on the second surface portion,.