VDF Fluoropolymer Binder Composition for Dry Electrode Metal Adhesion
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Solution Overview
Problem
Current dry electrode processes for batteries face challenges with adhesion of fluoropolymer binders to metal current collectors, particularly PTFE, which lacks sufficient adhesion while maintaining stability in electrolyte solvents and high temperatures.
Innovation Solution
Development of VDF-based copolymers with specific melting points and semi-crystalline properties that exhibit improved adhesion to metals, enabling their use as binders in dry electrode processes and extrusion at low temperatures, forming self-supporting films without the need for solvents or primers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTFE binder is used in dry electrode processes, then good cohesion with electrode active material and stability in electrolyte solvents at high temperatures is achieved, but adhesion to current collector deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the fluoropolymer binder by incorporating specific comonomers (VDF, HFP, TFE) in controlled ratios to achieve optimal balance between adhesion and stability
Solution Approach 2:
The patent creates a composite fluoropolymer system combining multiple monomer units (VDF, HFP, TFE) to achieve synergistic properties that neither monomer alone can provide, specifically improving both adhesion and solvent resistance
2Ease of manufacture
If PTFE binder is used to form free-standing films, then good processability is achieved, but adhesion to current collector deteriorates
Solution Approach 1:
The patent adjusts the molecular composition parameters of the fluoropolymer to enable both film formation and adhesion, using specific VDF/HFP/TFE ratios that provide appropriate melt behavior and surface properties
3Strength
If wet process is used for electrode manufacturing, then good adhesion to current collector is achieved, but drying time and cost increase
Solution Approach 1:
The patent extracts and eliminates the drying step from the electrode manufacturing process by using a dry process approach with fluoropolymer binders that provide sufficient adhesion without requiring solvent evaporation
Solution Approach 2:
The patent replaces the thermal drying process with a mechanical compaction process, using pressure and cold isostatic pressing to form electrodes without thermal treatment
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 VDF-based copolymers demonstrate enhanced adhesion to metal current collectors, facilitating efficient electrode production with improved processability and maintaining excellent electrical properties, suitable for use in secondary batteries and other electrochemical devices.
Implementation Method 1
polymer (A) has at least two melting points, one melting point lower than 220°C. and one melting point higher than 250°C.
Data Source
AI summary
The present invention relates to VDF-based fluoropolymers with outstanding metal-adhesion properties for use as a binding agent for electrodes for batteries.