Secondary Battery Electrode Lamination via Slurry Viscosity Control
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Solution Overview
Problem
Conventional methods for manufacturing secondary battery electrodes result in significant mixing between the active material layer and the insulating layer, leading to decreased charge and discharge capacity, increased battery resistance, and reduced insulation effects.
Innovation Solution
A method involving the application of a slurry for the insulating layer onto the active material layer before it is dried, with specific selection of binders and thickeners to maintain distinct viscosities and molecular weights, ensuring minimal mixing and maintaining the insulation effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the liquid for the insulating layer is applied before the liquid for the active material layer is dried, then both layers can be laminated simultaneously, but significant mixing occurs at the interface which decreases charge and discharge capacity and increases battery resistance
Solution Approach 1:
The invention changes the viscosity parameter of the slurries by selecting binders/thickeners with different molecular weights. The first slurry (active material layer) has higher viscosity than the second slurry (insulating layer), preventing significant mixing while allowing simultaneous application and improving laminating efficiency without compromising battery performance
Solution Approach 2:
The invention uses composite slurry systems with different binder/thickener compositions. The first slurry contains binder/thickener with higher molecular weight for higher viscosity, while the second slurry contains binder/thickener with lower molecular weight for lower viscosity, creating a controlled interface that minimizes mixing while maintaining adhesion
2Strength
If the liquid for the insulating layer is applied before the liquid for the active material layer is dried, then local mixing improves adhesion of both layers, but significant mixing decreases insulation effect
Solution Approach 1:
The invention precisely controls the viscosity parameter to create an optimal balance. The first slurry has higher viscosity (preventing excessive mixing) while the second slurry has lower viscosity (allowing good wetting and adhesion). This parameter optimization ensures sufficient interfacial mixing for adhesion while maintaining insulation effectiveness
Solution Approach 2:
The invention creates different viscosity characteristics at different locations in the slurry system. At the interface region, controlled mixing occurs to provide adhesion, while the bulk regions maintain distinct layer identities with proper insulation. The local mixing is sufficient for bonding but limited to preserve insulation properties
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 efficiently manufactures electrodes with laminated structures that prevent mixing between layers, maintaining battery characteristics and enhancing insulation properties.
Implementation Method 1
a first binder or thickener for the slurry for the first layer and a second binder or thickener for the slurry for the second layer are selected such that when viscosities are measured for a first solution including solvent and the first binder or thickener dissolved in the solvent in a specific mass ration and a second solution including a solvent and the second binder or thickener dissolved in the solvent at the same mass ration as the mass ration of the first binder or thickener under the same conditions, the viscosity of the first solution is higher than the viscosity of the second solution
Data Source
AI summary
A secondary battery electrode manufacturing method comprises applying a slurry for a first layer to a current collector, applying a slurry for a second layer to the slurry for the first layer before the slurry for the first layer dries, and drying the slurries to obtain a laminated structure in which the first and second layers are laminated in this order on the current collector. A first and second binder or thickener for the respective slurries are selected such that when viscosities are measured for a first solution including solvent and the first binder or thickener dissolved in the solvent in a specific mass ratio and a second solution including a solvent and the second binder or thickener dissolved in the solvent at the same mass ratio under the same conditions, the viscosity of the first solution is higher than the viscosity of the second solution.