Electrode Embossing via Pendular State Moisture Control
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Solution Overview
Problem
The existing methods for producing electrodes with depressed portions face challenges such as non-uniform electrode reactions due to variations in density, adhesion issues during embossing, and incomplete permeation of the electrolyte solution, which affect the fluidity and releasability of the active material layer.
Innovation Solution
A method involving the preparation of a slurry with a specific solid fraction that forms a pendular or funicular state during drying, allowing for embossing without adhesion to the convex die and reducing density variations, followed by drying to create an active material layer with controlled depressed portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a convex die is pressed against the surface of a dried active material layer to form a depressed portion, then the depressed portion is formed as a pathway for electrolyte solution permeation, but the solid material is compressed at the bottom of the depressed portion causing local increase in density and non-uniform electrode reaction
Solution Approach 1:
The invention changes the moisture content parameter of the active material layer from a fully dried state to a partially dried state with 1-10% remaining moisture content. This parameter change allows the material to maintain sufficient fluidity during embossing to prevent density variation, while still forming well-defined depressed portions that serve as electrolyte pathways.
Solution Approach 2:
The invention applies preliminary drying to reduce the moisture content to a specific range (1-10%) before performing the embossing operation. This preliminary action prepares the material in an optimal state that balances fluidity for uniform compression and structural integrity for depressed portion formation, preventing the density variation problem that would occur with fully dried material.
2Manufacturing precision
If liquid is sprayed to the surface of the active material layer after drying to give fluidity to the solid material, then variations in density are reduced, but adhesion force is generated causing the solid material to adhere to the convex die
Solution Approach 1:
The invention performs preliminary drying to achieve a specific moisture content range (1-10%) before embossing, eliminating the need for post-drying liquid spraying. This preliminary action provides the necessary fluidity for uniform compression without generating excessive adhesion forces that would cause material to stick to the convex die during the embossing process.
Solution Approach 2:
The invention precisely controls the moisture content parameter within the 1-10% range, which is sufficient to provide fluidity for uniform density distribution during compression, yet low enough to prevent excessive adhesion to the convex die. This optimized parameter range resolves the contradiction between reducing density variation and preventing adhesion.
3Strength
If the active material layer is fully dried before embossing, then the structural integrity is improved, but the fluidity of solid material becomes low causing density variation
Solution Approach 1:
The invention optimizes the moisture content parameter to a specific range (1-10%) that provides sufficient fluidity for uniform density distribution during embossing, while maintaining enough structural integrity to form well-defined depressed portions. This optimized parameter eliminates the need for complete drying while preventing density variation.
Solution Approach 2:
The invention applies preliminary drying to achieve the optimal moisture content range before embossing, preparing the material with just enough fluidity to ensure uniform compression and density distribution, while maintaining sufficient structural integrity for depressed portion formation. This preliminary action resolves the contradiction between structural integrity and fluidity.
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 approach enhances the releasability and fluidity of the active material layer during embossing, reduces density variations, and improves the formation of uniform depressed portions, leading to more consistent electrode performance.
Implementation Method 1
The film passes 'a slurry state', 'a capillary state', 'a funicular state', and 'a pendular state' to reach 'a dry state'
Implementation Method 2
When the slurry applied to the substrate (a film) is dried, a liquid phase (the dispersion medium) is reduced and a gas phase (air bubbles, voids) is generated
Data Source
AI summary
A slurry is prepared by mixing an active material particle, a binder, and a dispersion medium. The slurry is applied to a surface of a substrate to form a first film. The first film is dried to form a second film. A convex die is pressed against a surface of the second film to form a depressed portion in the surface. After the depressed portion is formed, the second film is dried to form an active material layer. In the second film, a solid phase, a liquid phase, and a gas phase form a pendular state or a funicular state.