Dry Electrode Film PTFE Fibrillation for Thick Battery Electrodes
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Solution Overview
Problem
Conventional lithium battery electrode preparation methods require high dispersion of conductive agents, precise viscosity control, and high energy consumption, with limitations in producing thick electrodes and high solvent usage, leading to environmental issues and inconsistent fibrillation due to the specific properties of polytetrafluoroethylene (PTFE).
Innovation Solution
A dry electrode process involving low-temperature high-speed and high-temperature high-speed jet milling shears is used to fibrillate PTFE, reducing it to nanoscale and achieving uniform distribution, followed by rolling to form a self-supporting film on a current collector, eliminating solvent drying and enabling thick electrode production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional coating method is used to prepare electrode sheet, then the electrode can be formed with uniform structure, but the production process requires high energy consumption for solvent drying and has high cost for solvent recovery
Solution Approach 1:
The invention extracts and eliminates the solvent component from the electrode preparation process. By using a dry mixing approach instead of conventional slurry coating, the process removes the need for solvent drying and recovery operations, thereby significantly reducing energy consumption while still achieving uniform electrode structure through controlled mixing and fibrillation of PTFE binder
Solution Approach 2:
The invention replaces the thermal drying process with a mechanical fibrillation process. Instead of using heat to evaporate solvent and form the electrode structure, the process uses mechanical shear forces to fibrillate the PTFE binder, which then forms the electrode structure through self-assembly, eliminating the need for energy-intensive thermal drying
2Quantity of substance
If conventional coating method is used, then the electrode sheet can be produced, but the active material content is limited and thick electrode sheet cannot be prepared
Solution Approach 1:
The invention changes the key parameter of binder content and its physical state. By using high-molecular-weight PTFE and controlling its fibrillation degree through mechanical processing rather than relying on solvent-based coating parameters, the process enables production of thick electrode sheets with high active material content (up to 95-98 wt%) while maintaining manufacturability through controlled fibrillation processes
3Strength
If high-molecular-weight PTFE is used to facilitate fibrillation, then the electrode film can form properly, but the particle size of PTFE (500-700 μm) is much larger than active materials (<30 μm), making uniform mixing difficult and leading to segregation
Solution Approach 1:
The invention applies segmentation by dividing the PTFE particles through controlled fibrillation. The large PTFE particles (500-700 μm) are mechanically broken down into smaller fibrils during the mixing and rolling processes. This segmentation occurs in stages: initial mixing distributes the large particles, then rolling and shear forces progressively break them down into fine fibrils that uniformly entangle with active material particles, achieving both high strength and uniform composition
Solution Approach 2:
The invention applies preliminary action by pre-processing the PTFE through controlled fibrillation before final electrode formation. The PTFE is subjected to preliminary mixing and mechanical breakdown to reduce particle size and create fibrillar structures that are more prone to uniform distribution. This preliminary fibrillation prepares the PTFE for subsequent processing steps, ensuring uniform mixing while maintaining the high-molecular-weight characteristics needed for proper film formation
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 enhances tensile strength, reduces binder usage, and allows for electrodes with varying thicknesses, improving energy density and production efficiency while minimizing environmental impact.
Implementation Method 1
The primary steps of the process involve: a conductive agent, a binder and an electrode active material are mixed evenly, and then the mixed material is subjected to high-speed shear forces to fibrillate the binder PTFE
Implementation Method 2
subjecting the pulverized mixed material to a primary jet milling shear to obtain a milled-sheared mixed material
Implementation Method 3
conditions of the primary jet milling shear include: a gas stream temperature of -10°C-10°C, a compressed gas stream pressure of 0.7 MPa to 0.9 MPa, and a shear rotational speed of 8000 rpm to 12000 rpm
Implementation Method 4
finally the mixed material is subjected to rolling and further fibrillation to prepare a self-supporting electrode film coating on a current collector
Data Source
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AI summary
Disclosed are a dry electrode film, a preparation method therefor, and an electrode and a battery, which belong to the technical field of batteries. The method in the present application includes: mixing polytetrafluoroethylene, an active material, and a conductive agent, and pulverizing to obtain a pulverized mixed material; subjecting the pulverized mixed material to a primary jet milling shear to obtain a milled-sheared mixed material; wherein a condition of the primary shear includes: a gas stream temperature of -10°C-10°C, a gas stream pressure of 0.7-0.9 MPa, and a rotational speed of 8000-12000 rpm; subjecting the milled-sheared mixed material to a secondary jet milling shear and fibrillation to obtain a fibrillized material; and subjecting the fibrillized material to a secondary fibrillation treatment to obtain the dry electrode film. The method in the present application can significantly improve the tensile strength of the electrode film, increase the liquid absorption rate of the electrode, and reduce the electrical resistivity of the electrode.