Two-Shaft Kneader Mist Solvent Charging for Electrode Paste
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Solution Overview
Problem
Existing methods for producing aqueous electrode paste result in large microgels due to the swelling of insoluble cellulose in the thickener, leading to coating defects and increased battery resistance, as the solvent is not effectively microparticulated during the kneading process.
Innovation Solution
A two-shaft kneader is used to thickly knead a powder and aqueous solvent mixture, with a misty aqueous solvent having an average liquid droplet diameter of 1 μm or more and an average particle diameter of the thickener or less being sprayed during the dilution process to reduce microgel size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rod-like aqueous solvent is charged through an orifice plate during dilution, then the solvent is easily charged, but large microgels are generated due to rapid swelling of insoluble cellulose
Solution Approach 1:
The aqueous solvent is segmented into fine droplets using a mist generator before being charged into the kneader. This segmentation prevents rapid localized swelling of cellulose that occurs with rod-like solvent charging, thereby controlling microgel size while maintaining ease of operation
Solution Approach 2:
The physical state parameter of the aqueous solvent is changed from rod-like form to mist form with controlled droplet diameter (1 μm or more). This parameter change transforms the charging process to prevent excessive swelling while maintaining operational simplicity
2Ease of manufacture
If the aqueous solvent is charged en bloc in a kneader, then the charging process is simple, but large microgels remain in the electrode paste causing coating defects
Solution Approach 1:
The charging process is modified by changing the physical state of the solvent from en bloc (bulk) charging to mist charging. This parameter change maintains the simplicity of the charging process while producing fine droplets that prevent large microgel formation, thereby improving coating quality
Solution Approach 2:
A mist generator is introduced to transform the aqueous solvent into a mist form before charging. This pneumatic/hydraulic device maintains ease of manufacture by automating the mist generation while controlling droplet size to prevent coating defects
3Ease of operation
If manual scraping is performed during kneading, then the electrode paste can be removed from the stirring blade, but working hours and labor costs increase
Solution Approach 1:
The two-shaft kneader design enables the electrode paste to be automatically discharged without manual scraping intervention. The system serves itself by using the kneading action and shaft rotation to naturally discharge the paste, thereby improving productivity while maintaining operational ease
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 effectively reduces microgel size, minimizes coating defects, and enhances battery yield by preventing excessive lithium precipitation and resistance increases, while also reducing labor costs by eliminating the need for manual scraping of the electrode paste.
Implementation Method 1
The thickener except a part thereof absorbs the aqueous solvent during thick kneading and swells
Implementation Method 2
charging a misty aqueous solvent having an average liquid droplet diameter of 1 μm or more and an average particle diameter (D50) of the thickener or less inside of the two-shaft kneader by spraying
Data Source
AI summary
A method for producing an aqueous electrode paste includes charging a powder made of an active material and a thickener and an aqueous solvent inside of a two-shaft kneader, and, using the two-shaft kneader, thickly kneading the powder and the aqueous solvent to generate a mixture; and charging a misty aqueous solvent having an average liquid droplet diameter of 1 μm or more and an average particle diameter (D50) of the thickener or less inside of the two-shaft kneader by spraying, and using the two-shaft kneader, diluting the mixture with the charged aqueous solvent.