Dry Battery Electrode Binder Fibrillation for Stronger Mixture Sheets
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Solution Overview
Problem
Existing dry methods for producing non-aqueous electrolyte secondary battery electrodes face challenges with binder migration during drying, leading to uneven binder distribution and reduced electrode strength. Additionally, insufficient or excessive fibrillation of the binder can result in weak or unformable mixture sheets.
Innovation Solution
The electrode comprises a mixture sheet with a fibrillated fibrous binder, where the binder's crystallite size is regulated to be between 20 nm and 32 nm, and the reduction rate of the crystallite size after fibrillation is between 4% and 40%, ensuring a dense and strong mixture sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the binder is excessively fibrillated, then the mixture sheet strength decreases, but the binder distribution becomes more uniform
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite size of the fibrillated binder within a specific range (20-32 nm) and limiting the reduction rate of crystallite size (4-40%). This quantitative parameter control resolves the contradiction by finding the optimal fibrillation degree that balances binder distribution uniformity with mixture sheet strength, avoiding both insufficient and excessive fibrillation.
2Strength
If the binder is insufficiently fibrillated, then the mixture sheet strength increases, but the binder distribution becomes uneven
Solution Approach 1:
The patent resolves this contradiction by establishing minimum parameter thresholds: crystallite size must be at least 20 nm and reduction rate must be at least 4%. These parameter settings ensure sufficient fibrillation for uniform binder distribution while preventing excessive fibrillation that would compromise mixture sheet strength.
3Ease of manufacture
If the wet method is used for electrode production, then the coating process is simple, but binder migration occurs during drying
Solution Approach 1:
The patent replaces the wet coating method with a dry method, substituting the liquid-based application process with a mechanical mixing and forming process. This eliminates the drying step that causes binder migration, while the controlled fibrillation (crystallite size 20-32 nm, reduction rate 4-40%) ensures uniform binder distribution in the resulting mixture sheet.
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 results in a mixture sheet with high tensile strength and smooth surface, leading to excellent cycle characteristics for the non-aqueous electrolyte secondary battery, with the binder being uniformly distributed and the electrode maintaining its integrity during charge and discharge cycles.
Implementation Method 1
the binder is fibrillated so that a reduction rate of a crystallite size of the binder is greater than or equal to 4% and less than or equal to 40%
Implementation Method 2
a mixture sheet with high tensile strength and smooth surface, leading to excellent cycle characteristics
Implementation Method 3
the binder has a crystallite size of greater than or equal to 20 nm and less than or equal to 32 nm as determined by X-ray diffractometry
Data Source
AI summary
An electrode (10) according to one embodiment of the present invention comprises a core member (11) and a mixture sheet (12) joined to the surface of the core member (11). The mixture sheet (12) includes an active material (21) and a fibrous binder (22) having been fibrillated. The crystalline size of the binder (22), which is obtained by X-ray diffraction measurement, is 20-32 nm.