PTFE Dispersion Resin for Dry Electrodes With High Fiber Formation
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Solution Overview
Problem
Existing lithium-ion battery electrode binders in wet forming processes hinder contact between activated carbon particles and conductive agent particles, leading to poor conductivity and capacity retention due to solvent interactions, and existing polytetrafluoroethylene resins do not achieve desired tightness in particle contacts.
Innovation Solution
A method involving polymerization of tetrafluoroethylene monomers under controlled conditions to produce a polytetrafluoroethylene dispersion resin with specific density and particle size, using an oxidation-reduction initiator system and controlled temperature and stirring, followed by coagulation to achieve a fibrous state for improved electrode binder performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet forming process with binder layer is used, then electrode formation is achieved, but conductivity and capacity retention deteriorate due to hindered particle contacts and solvent side reactions
Solution Approach 1:
The invention extracts and eliminates the solvent component from the electrode formation process by using a dry forming method. Instead of using liquid binders that require solvent evaporation, the patent employs dry polymer binder powder that directly binds active material particles without introducing harmful solvents, thereby eliminating solvent side reactions while maintaining electrode integrity
Solution Approach 2:
The invention applies preliminary action by pre-coating active material particles with conductive agent before binder addition, and using dry polymer binder powder that is pre-prepared with controlled particle size and morphology. This preliminary preparation ensures optimal particle contacts and conductive networks are established before electrode assembly, improving conductivity and capacity retention from the outset
2Reliability
If traditional polytetrafluoroethylene resins are used as dry electrode binder, then binder function is achieved, but particle contact tightness deteriorates resulting in reduced conductivity
Solution Approach 1:
The invention applies parameter changes by precisely controlling the average particle size of polytetrafluoroethylene dispersion resin within 10-100 μm range and controlling the solid content at 30±3 wt%. These parameter optimizations ensure the binder particles are small enough to fill gaps between active material particles effectively, creating tight contacts and improving conductivity while maintaining manufacturability
Solution Approach 2:
The invention applies local quality by ensuring the polytetrafluoroethylene dispersion resin exhibits enhanced fiber forming effect specifically at the particle interfaces and contact points. The controlled particle size and density (1.01-1.03 g/cm³) create localized regions of tight particle contacts where the binder most needs to function, improving conductivity at critical interfaces rather than uniformly throughout the electrode
3Ease of manufacture
If polytetrafluoroethylene dispersion resin with large particle size is used, then ease of manufacture is improved, but fiber forming effect and conductivity deteriorate
Solution Approach 1:
The invention applies parameter changes by optimizing the average particle size to 10-100 μm and solid content to 30±3 wt%, finding the optimal balance between ease of manufacture and fiber forming effect. These parameter ranges are large enough to facilitate handling and processing but small enough to ensure effective fiber formation and tight particle contacts, resolving the contradiction between manufacturability and performance
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 resulting polytetrafluoroethylene dispersion resin enhances electrode conductivity and capacity retention by ensuring tight particle contacts, resulting in high-density, conductive, and high-capacity electrodes.
Implementation Method 1
subjecting gas-phase tetrafluoroethylene monomers to polymerization reaction with an oxygen content of ≤ 30 ppm under a pressure of 2.0 to 3.0 Mpa, and at a temperature of 62°C to 70°C
Implementation Method 2
followed by coagulation to achieve a fibrous state for improved electrode binder performance
Data Source
AI summary
The present application relates to the field of polymer materials and specifically relates to a polytetrafluoroethylene dispersion resin for a dry electrode binder and a preparation method thereof. The polytetrafluoroethylene dispersion resin prepared by the method does not contain PFOA, the SSG is 2.150 to 2.160, the average particle size is 10 to 100 µm , has excellent fiber forming performance and a high fiber forming rate, and is not prone to wire breakage. When the electrode binder is used as a dry electrode binder, active carbon particles and conductive agent particles can be contacted more tightly in a fiber state, such that the electrode has the advantages of large density, excellent conductivity, high capacity, etc.