Die Coater Shim Geometry for Uniform Electrode Edge Coating
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Solution Overview
Problem
Existing die coaters struggle with uneven slurry thickness distribution, particularly at the edge portions of electrodes, leading to NP ratio reversals during secondary battery manufacturing.
Innovation Solution
A shim for the die coater with guides and sub-guides that control the slurry discharge line, featuring steps and varying thicknesses to ensure smooth application on edge portions, reducing NP ratio reversals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional die coater is used with uniform thickness design, then the manufacturing process is simple, but the slurry thickness distribution becomes uneven at edge portions causing NP ratio reversal
Solution Approach 1:
The shim incorporates varying thickness regions (first region with thickness t1, second region with thickness t2 where t1 > t2) to create different flow resistance characteristics in different areas. This local variation in shim thickness enables the slurry to be distributed more uniformly across the discharge port, particularly improving edge portion coating quality without requiring complete redesign of the die coater structure.
Solution Approach 2:
The shim is divided into multiple regions (first region, second region, third region) with different thickness characteristics. The first region has greater thickness than the second region, and the third region has different thickness than the first region. This segmentation allows independent optimization of slurry flow control in different areas, resolving the uniformity issue while maintaining manageable structural complexity.
2Manufacturing precision
If the shim thickness is increased to improve edge portion coating, then the slurry application uniformity improves, but the device complexity increases
Solution Approach 1:
Rather than uniformly increasing shim thickness throughout, the invention applies increased thickness (first region with thickness t1) only in specific areas where additional slurry flow control is needed, while maintaining thinner sections (second region with thickness t2) in other areas. This localized approach improves edge portion coating precision without proportionally increasing overall device complexity.
3Area of stationary object
If the discharge port is made thin and wide for broad coating, then the coating width is improved, but the slurry thickness uniformity deteriorates
Solution Approach 1:
The shim acts as an intermediary element positioned between the discharge port and the slurry flow. By introducing this intermediate component with strategically varied thickness, the system achieves both broad coating width (through the inherently thin and wide discharge port) and improved thickness uniformity (through the shim's differential thickness regions that regulate flow distribution).
Solution Approach 2:
The shim's varying thickness regions (t1 in first region, t2 in second region where t1 > t2) create localized flow resistance that compensates for the wide discharge port's tendency toward non-uniform distribution. This local quality variation in the shim enables the discharge port to maintain its advantageous wide geometry while achieving uniform slurry application across the entire coating width.
Data Source
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AI summary
The present technology relates to a shim for a die coater, a die coater including the shim, and a lithium secondary battery including a positive electrode manufactured using the die coater of the present invention, and according to the present technology, it is possible to smoothly apply slurry on the edge portion.