Battery Electrode Slurry Pressing for Uniform Coating Thickness
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Solution Overview
Problem
The manufacturing process of rechargeable batteries often results in a thickness difference between the edge and central portions of the active material layer, leading to gaps that can cause short circuits due to lithium salt accumulation.
Innovation Solution
A manufacturing system and method that includes a pressurizing device with a hydrophobic coating and a pressurizing member to uniformly distribute the slurry thickness, using distance and thickness measurement members to adjust the pressurizing process, ensuring uniformity and preventing local thickness increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a slurry is applied on a substrate using conventional coating methods, then the coating process is simple and fast, but the thickness of the edge portion becomes thinner than the central portion due to surface tension
Solution Approach 1:
The slurry is applied with a preliminary excess thickness at the edge portion before drying. This preliminary action compensates for the thickness reduction that will occur during the drying process, ensuring that the final dried layer has uniform thickness across the entire substrate surface.
Solution Approach 2:
The invention changes the thickness parameter of the slurry layer as a function of position on the substrate. Specifically, the slurry is applied with greater thickness at the edge portions and appropriate thickness at the central portion, creating a non-uniform initial distribution that results in uniform final thickness after drying.
2Reliability
If the slurry is dried without thickness adjustment, then the drying process is simple and fast, but fine spaces (gaps) are generated between the edge portion of the active material layer and the separator
Solution Approach 1:
The thickness of the slurry layer is adjusted in advance during the coating process, creating an excess thickness at the edge portions. This preliminary action prevents the formation of gaps during drying, thereby eliminating the risk of lithium salt accumulation and short circuits between the active material layer and separator.
Solution Approach 2:
The invention applies a counter-action to the surface tension effect that causes edge thinning. By intentionally applying the slurry with greater thickness at the edges, the method counteracts the thinning effect that occurs during drying, preventing the formation of harmful gaps.
3Manufacturing precision
If the pressurizing member is positioned close to the substrate, then the thickness uniformity can be improved, but the risk of substrate deformation or damage increases
Solution Approach 1:
The pressurizing member is designed with locally varying characteristics, including regions with different hardness, elasticity, or surface properties. This allows the pressurizing member to apply appropriate pressure distribution - sufficient to uniformize slurry thickness but distributed in a way that prevents localized excessive pressure that could deform or damage the substrate.
Solution Approach 2:
The pressurizing member is designed to be elastically deformable, allowing it to dynamically adapt its shape and pressure distribution during the pressing process. This dynamic behavior enables the member to conform to the substrate surface while distributing pressure evenly, achieving thickness uniformity without causing substrate damage.
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 system minimizes thickness differences, improving electrode plate planarity and preventing gaps between the active material layer and separator, thereby reducing the risk of short circuits.
Implementation Method 1
a hydrophobic coating portion on a portion of the base portion that is in contact with the slurry, the hydrophobic coating portion having a hydrophobic functional group
Data Source
AI summary
A manufacturing system of a rechargeable battery may include a transporting device configured to transport a substrate, a coating device configured to apply a slurry to the substrate, a pressurizing device including a pressurizing member located spaced apart from the transporting device and having a size corresponding to the slurry applied to the substrate, and a driving member configured to move the pressurizing member toward the slurry or away from the slurry, and configured to pressurize the slurry so that a thickness of the slurry may become uniform, and a drying device configured to dry the pressurized slurry.