Dry Electrode Film Processing to Preserve Binder Fibrilization
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Solution Overview
Problem
Existing methods for manufacturing dry electrodes for electrochemical devices face challenges such as micronization of active materials and degradation of mechanical properties due to high-shear mixing processes, leading to issues like pinholes, cracks, and uneven drying, which affect the quality and performance of electrodes.
Innovation Solution
A dry electrode manufacturing method involving a high-temperature low-shear mixing process followed by pulverization, which minimizes active material micronization and maintains binder fibrilization, ensuring improved mechanical properties like flexibility and strength, and controlling crystallinity through differential scanning calorimetry to optimize processing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-shear mixing process is used to manufacture dry electrode, then binder fibrilization is achieved, but active material micronization and degradation of mechanical properties occur
Solution Approach 1:
The patent changes the mixing parameters from high-shear to low-shear conditions, and controls the mixing temperature within 0°C to 100°C to prevent active material micronization while achieving binder fibrilization. This parameter optimization resolves the contradiction between mechanical property improvement and particle size control.
Solution Approach 2:
The patent employs a two-stage mixing process: first high-shear mixing for initial binder fibrilization, then low-shear mixing for final electrode formation. This periodic application of different shear forces allows binder fibrilization to occur while preventing active material degradation in the final stage.
2Strength
If high-shear mixing is applied to achieve binder fibrilization, then adhesion is improved, but binder fibers are cut and flexibility is degraded
Solution Approach 1:
The patent uses a two-stage mixing approach where high-shear mixing is applied first to achieve binder fibrilization and adhesion, followed by low-shear mixing to preserve fiber integrity and flexibility. This periodic action sequence resolves the contradiction between adhesion improvement and flexibility maintenance.
Solution Approach 2:
The patent performs binder fibrilization as a preliminary action before final electrode formation. By achieving the necessary adhesion through binder fibrilization in advance, the subsequent low-shear mixing can focus on maintaining flexibility without compromising adhesion.
3Productivity
If conventional drying process is used to remove solvent, then electrode formation is completed, but pinholes and cracks are generated
Solution Approach 1:
The patent extracts and eliminates the solvent from the electrode mixture entirely, adopting a dry mixing and forming process. This removes the source of evaporation-related defects (pinholes and cracks) while maintaining productivity through efficient dry processing methods.
4Manufacturing precision
If drying apparatus is used to control solvent evaporation rate, then uniform drying is achieved, but manufacturing cost and time increase
Solution Approach 1:
The patent eliminates the solvent from the system entirely through dry processing methods, removing the need for complex drying apparatuses. This achieves uniform electrode formation without the need for expensive and time-consuming controlled drying equipment.
Solution Approach 2:
The patent employs self-service mixing and forming methods where the electrode components are directly mixed and formed without solvent, eliminating the need for external drying apparatuses and their associated complexity and costs.
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 method effectively reduces micronization and enhances mechanical properties, ensuring stable film formation, improved handling, and efficient processing by maintaining binder fibrilization and controlling crystallinity, resulting in electrodes with sufficient tensile strength and elongation.
Implementation Method 1
the binder is fibrilized through a high-shear mixing process, such as jet milling
Implementation Method 2
the mixed powder for electrode is compacted to form an electrode structure
Implementation Method 3
the compacted electrode structure is sintered at a high temperature
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed is a method for manufacturing a dry electrode. The method allows determination of the micro-fibrilization degree of a binder resin from the crystallinity of the binder resin. Based on this, the processing conditions of mixed powder for electrode or an electrode film may be controlled. In this manner, it is possible to check and control the processing conditions easily and efficiently. In addition, the method for manufacturing a dry electrode includes a kneading step using a kneader under a low speed and high temperature and pulverization step. Therefore, there is no problem of blocking of a flow path caused by aggregation of the ingredients, which is favorable to mass production.