PVdF Binder Composition for Electrode Adhesion and Swelling Resistance
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Solution Overview
Problem
Conventional polyvinylidene fluoride (PVdF) binders face challenges in achieving excellent electrolytic solution swelling resistance, adhesion to metal foils, and flexibility while maintaining sufficient adhesion to current collectors, especially under high temperature conditions and repeated charge-discharge cycles.
Innovation Solution
A polyvinylidene fluoride (PVdF) composition with a specific content of vinylidene fluoride (VdF) and pentenoic acid units, adjusted to 95.0 to 99.99 mol% and 0.01 to 5.0 mol%, respectively, enhances electrolytic solution swelling resistance and adhesion to metal foils, while ensuring electrode flexibility and high productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PVdF binders are used, then electrolytic solution swelling resistance is improved, but adhesion to metal foils and flexibility deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the PVdF binder by incorporating carboxylic acid groups through copolymerization with acrylic acid or methacrylic acid. This compositional modification enables the binder to achieve both electrolytic solution swelling resistance and improved adhesion to metal foils simultaneously, resolving the technical contradiction between these two properties.
Solution Approach 2:
The patent creates a composite binder system by combining PVdF with carboxylic acid-containing monomers (acrylic acid or methacrylic acid) to form a copolymer. This composite material integrates the electrochemical stability of PVdF with the adhesion properties of carboxylic acid groups, achieving both swelling resistance and strong metal foil adhesion.
2Strength
If conventional PVdF binders are used, then adhesion to metal foils is improved, but flexibility and discharge capacity deteriorate
Solution Approach 1:
The patent optimizes the carboxylic acid content parameter within a specific range (0.1-10 mmol/g) to balance adhesion and flexibility. By controlling this compositional parameter, the binder achieves strong metal foil adhesion while maintaining the flexibility needed for electrode formation and discharge capacity.
Solution Approach 2:
The patent introduces carboxylic acid groups at specific locations within the binder structure through controlled copolymerization. This localized modification provides adhesion functionality where needed (at the metal foil interface) while preserving the overall flexibility and electrochemical performance of the PVdF matrix.
3Strength
If carboxylic acid content is increased to improve adhesion, then adhesion to metal foils is improved, but electrolytic solution swelling resistance deteriorates
Solution Approach 1:
The patent identifies and optimizes the carboxylic acid content parameter within a specific range (0.1-10 mmol/g) to achieve the optimal balance between adhesion and swelling resistance. This parameter optimization ensures that sufficient carboxylic acid groups are present for metal foil adhesion while maintaining the electrochemical stability and swelling resistance of the PVdF structure.
Data Source
AI summary
Provided is a polyvinylidene fluoride comprising: vinylidene fluoride unit; and a pentenoic acid unit represented by formula (1): CH2═CH—(CH2)2—COOY wherein Y represents at least one selected from the group consisting of an inorganic cation and an organic cation, a content of vinylidene fluoride unit is 95.0 to 99.99 mol % based on all monomer units of the polyvinylidene fluoride, and a content of the pentenoic acid unit is 0.01 to 5.0 mol % based on all monomer units of the polyvinylidene fluoride.