Differential Roller Pressing for Dry Electrode Thickness Control
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Solution Overview
Problem
The existing wet manufacturing method for positive electrode materials in secondary batteries faces challenges such as non-uniform thickness, environmental harm due to solvent drying, and deteriorated binder adhesion, while the dry manufacturing method suffers from binder fiberization issues.
Innovation Solution
An electronic device with rollers rotating at different speeds forms a film of a mixture without solvents, applying shear force to maximize binder fiberization and adhesion, and incorporates a current collector to create electrodes with controlled thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet manufacturing method is used, then electrode slurry can be applied onto current collector, but manufacturing precision of electrode thickness is poor and environmental harm occurs due to solvent drying
Solution Approach 1:
The invention changes the physical state parameter of the manufacturing process from wet (slurry with solvent) to dry (powder mixture without solvent). By eliminating the solvent component entirely, the process achieves both environmental benefits and improved thickness uniformity while maintaining ease of manufacture through the straightforward mixing and pressing of dry powders.
Solution Approach 2:
The invention utilizes the phase transition concept by removing the liquid solvent phase entirely, transitioning directly from solid powder mixing to solid electrode formation through pressing. This eliminates the drying phase transition that causes environmental harm and thickness variation, achieving uniform thickness through controlled mechanical pressing of the dry mixture.
2Ease of manufacture
If wet manufacturing method is used, then electrode can be manufactured, but large amount of carbon dioxide is generated due to solvent drying which harms environment
Solution Approach 1:
The invention extracts and removes the harmful solvent component from the manufacturing process. By taking out the NMP solvent that requires drying and generates carbon dioxide, the process eliminates environmental pollution while maintaining the core manufacturing functionality through direct pressing of the dry powder mixture onto the current collector.
Solution Approach 2:
The invention converts the potential harm of requiring a drying process into a benefit by eliminating the drying step entirely. The dry manufacturing method transforms what would have been a harmful environmental process (solvent evaporation generating CO2) into an environmentally friendly process that requires no thermal drying and generates no harmful emissions.
3Object-generated harmful factors
If dry manufacturing method is used to avoid solvent drying, then environmental harm is reduced, but binder fiberizes and adhesion deteriorates
Solution Approach 1:
The invention applies preliminary action by pre-mixing the binder with conductive powder and active material powder in specific proportions before pressing. This preliminary mixing ensures uniform distribution of the binder throughout the mixture, and the subsequent pressing action activates the binder's adhesive properties through mechanical compression, preventing fiberization and ensuring strong adhesion without requiring solvent drying.
4Strength
If rollers rotate at different speeds to apply shear force, then binder adhesion is maximized, but device complexity increases
Solution Approach 1:
The invention applies dynamics by making the roller speeds variable rather than fixed. The first roller rotates at a different speed than the second roller, creating a dynamic speed difference that generates shear force during the pressing process. This dynamic approach maximizes binder adhesion through controlled shear while maintaining relatively simple device structure through straightforward speed control mechanisms.
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 method reduces manufacturing time and costs, minimizes environmental pollution, and enhances mechanical and electrical properties of electrodes, enabling efficient production of high-capacity batteries.
Implementation Method 1
a drive unit that rotates the first roller at a first speed and rotates the second roller at a second speed different from the first speed so that a mixture fed between the first roller and the second roller is formed into a film
Data Source
AI summary
According to embodiments, provided is an electronic device comprising: a first roller; a second roller arranged to face the first roller; and a drive unit that rotatably drives the first roller at a first speed and rotatably drives the second roller at a second speed to form, into a film, a mixture being input between the first roller and the second roller.