Positive Electrode Slurry Heating for Uniform Battery Coating
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Solution Overview
Problem
The migration of conductive materials and binders due to low-viscosity solvent flow during the drying of positive electrode slurries for secondary batteries leads to a decrease in the adhesive force between the current collector and the positive electrode active material layer.
Innovation Solution
A fabrication method for a positive electrode that involves heating a slurry composition containing a positive electrode active material, a binder, and a solvent to a temperature below its boiling point, applying it onto a current collector, and then cooling it, which helps in maintaining a high viscosity and preventing the migration of small particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the content of the solvent in the electrode slurry is decreased to increase the viscosity of the electrode slurry, then the migration of small particles (binder and conductive material) is suppressed, but the fluidity of the electrode slurry rapidly decreases
Solution Approach 1:
The patent changes the temperature parameter of the electrode slurry to adjust its viscosity dynamically. By heating the slurry to a temperature between 20°C to 80°C, the viscosity is reduced to achieve appropriate fluidity for coating operations, while maintaining high solid content (70-90 wt%) to prevent particle migration during drying.
2Stability of the object's composition
If the content of the solvent in the electrode slurry is decreased to increase the viscosity of the electrode slurry, then the migration of small particles (binder and conductive material) is suppressed, but the adhesive force between the current collector and the electrode active material layer decreases
Solution Approach 1:
The patent utilizes temperature as a controllable parameter to achieve optimal viscosity during the coating process. By maintaining the slurry at elevated temperature (20-80°C) during application, the slurry exhibits improved fluidity and wetting characteristics, ensuring strong adhesive force between the electrode active material layer and current collector, while the high solid content prevents particle migration.
3Loss of substance
If the viscosity of the electrode slurry is increased to decrease the content of solvent remaining in the secondary battery, then the migration of small particles is prevented, but the workability of the electrode slurry decreases
Solution Approach 1:
The patent employs temperature control to decouple the relationship between viscosity and solid content. By heating the slurry to 20-80°C during manufacturing operations, the patent achieves high workability despite high solid content (70-90 wt%), allowing for easy coating and processing. The high solid content ensures minimal solvent remains in the final battery product.
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 method enhances the adhesive force between the current collector and the positive electrode active material layer, improves the uniformity of the electrode thickness, and maintains the electrode's fluidity, thereby addressing the issues of non-uniform distribution and decreased adhesive force caused by high-viscosity slurries.
Implementation Method 1
heating a slurry composition for a positive electrode containing a positive electrode active material, a binder, and a solvent to a temperature lower than a boiling point (Tb) of the solvent
Implementation Method 2
cooling the applied slurry composition for a positive electrode
Implementation Method 3
drying the positive electrode slurry
Data Source
AI summary
The present invention provides a fabrication method of a positive electrode for a secondary battery, including: (a) heating a slurry composition for a positive electrode containing a positive electrode active material, a binder, and a solvent to a temperature lower than a boiling point (Tb) of the solvent; (b) applying the heated slurry composition for a positive electrode onto a current collector; and (c) cooling the applied slurry composition for a positive electrode.