Sulfide Electrolyte Mixture Sheet Using Solvent-Free PTFE Fibrils
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Solution Overview
Problem
Conventional methods for producing solid-state secondary battery mixtures often require solvents that degrade sulfide-based solid-state electrolytes, limiting battery performance and requiring the use of solvents with low flash points and limited binder resin compatibility, which complicates handling and production efficiency.
Innovation Solution
A secondary battery mixture using a fibrillatable resin like polytetrafluoroethylene (PTFE) as a binder, eliminating the need for solvents and allowing for the formation of a mixture sheet without a support, enhancing handling and flexibility, and reducing electrolyte deterioration by forming fibrils with a median diameter of 100 nm or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional solvents are used to dissolve binder resin, then the binder can be applied to form a mixture sheet, but the solvents degrade sulfide-based solid-state electrolytes and have low flash points, limiting battery performance and complicating handling
Solution Approach 1:
The invention extracts and eliminates the solvent component from the conventional slurry coating process. By using a dry mixing method where binder resin particles are directly mixed with active material particles without any solvent, the patent removes the source of electrolyte degradation while maintaining binder functionality through particle-level dispersion and adhesion.
Solution Approach 2:
The invention replaces the chemical dissolution mechanism (solvent-based) with a mechanical dispersion mechanism. The binder resin is dispersed as fine particles through mechanical mixing, and adhesion is achieved through mechanical interlocking and surface contact rather than chemical dissolution, thereby eliminating solvent-related degradation issues.
2Ease of manufacture
If solvents with low flash points are used, then binder resin can be dissolved and applied, but handling becomes complicated and safety risks increase
Solution Approach 1:
The invention extracts and eliminates the solvent component from the process entirely. By using a solvent-free dry mixing method, low flash point safety hazards are completely removed while binder functionality is maintained through alternative particle-level dispersion and adhesion mechanisms.
3Stability of the object's composition
If a support is used to form the mixture sheet, then the sheet structure is stable during production, but flexibility and handling are reduced
Solution Approach 1:
The invention enables the mixture sheet to be self-supporting without requiring an external support structure. By optimizing the particle size distribution, binder content, and compression conditions, the sheet achieves sufficient mechanical integrity through its own composition, allowing it to be handled and processed independently while maintaining flexibility.
4Ease of manufacture
If fibrils with larger diameter are formed, then the binder structure is easier to form, but ion conductivity is reduced
Solution Approach 1:
The invention changes the critical parameter of fibril diameter to 100 nm or less, which is significantly smaller than conventional fibrils. This parameter change enables sufficient ion conductivity by reducing transport resistance while the fibrillar structure still provides effective binder functionality. The fine fibril diameter is achieved through controlled shear treatment conditions.
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 approach enables the production of a sulfide-based solid-state secondary battery mixture sheet with improved ion conductivity, flexibility, and reduced electrolyte deterioration, while avoiding solvent-related performance degradation and handling issues.
Implementation Method 1
a resin that forms fibrils, such as a polytetrafluoroethylene resin, is also used as a binder by fibrillating the resin
Implementation Method 2
Patent Literature 1 discloses a method for producing an electrode in which polytetrafluoroethylene is fibrillated by subjecting a mixture including an active material and a polytetrafluoroethylene mixed binder material to a high shear treatment with a jet mill
Data Source
AI summary
The present disclosure provides a secondary battery mixture containing a sulfide-based electrolyte that has good properties, a secondary battery mixture sheet containing the secondary battery mixture, and a solid-state secondary battery using the secondary battery mixture sheet. The secondary battery mixture includes a sulfide-based solid-state electrolyte and a binder, wherein the binder is a fibrillatable resin. The binder preferably has a fibrous structure with a fibril diameter (median value) of 100 nm or less.