Aqueous PVDF Binder for Lithium Ion Battery Electrodes
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Solution Overview
Problem
The electronics industry faces challenges in producing smaller, lighter batteries due to the toxicity and environmental hazards of organic solvents like N-methyl-2-pyrrolidone (NMP) used in polyvinylidene fluoride (PVDF) binders, which are essential for electrode adhesion and interconnectivity in electrical storage devices.
Innovation Solution
An aqueous dispersion of polyvinylidene fluoride (PVDF) with a (meth)acrylic polymer dispersant, a crosslinking agent, and an organic diluent is developed, creating a stable slurry that maintains interconnectivity and adhesion without the need for toxic organic solvents, suitable for lithium ion secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NMP is used as a solvent for PVDF binders, then adhesion and interconnectivity are improved, but toxicity and environmental hazards increase
Solution Approach 1:
The patent uses water as an intermediary solvent instead of NMP, combined with a specific PVDF copolymer composition (containing 5-20 mol% of a specific monomer unit) that enables the polymer to achieve adequate dissolution and binding performance in aqueous environments. This intermediary approach allows replacement of the toxic solvent while maintaining functional performance.
Solution Approach 2:
The invention changes the chemical composition parameters of the PVDF binder by incorporating specific copolymer components (5-20 mol% of a monomer unit with specific properties) to modify the polymer's solubility characteristics. This parameter change enables the binder to function effectively in water-based systems rather than requiring NMP, thus eliminating toxicity while preserving adhesion properties.
2Ease of manufacture
If organic solvents are used for PVDF dispersion, then manufacturing capability is improved, but safety and environmental risks increase
Solution Approach 1:
Water serves as a safe intermediary medium to disperse PVDF particles, replacing flammable and toxic organic solvents. The specific PVDF copolymer composition enables adequate dispersion and binding performance in this aqueous environment, maintaining manufacturing capability while eliminating safety and environmental hazards associated with organic solvents.
Solution Approach 2:
The invention employs water, an abundant, non-toxic, and inexpensive substance, as the dispersion medium. This replaces costly and hazardous organic solvents that require special handling, storage, and disposal procedures. Water can be easily removed through drying processes, leaving the desired electrode structure without residual contamination.
3Object-affected harmful factors
If aqueous PVDF composition is used, then safety and environmental issues are improved, but adhesion and interconnectivity may deteriorate
Solution Approach 1:
The invention modifies the PVDF polymer structure by incorporating 5-20 mol% of a specific copolymer component that enhances water compatibility and binding performance. This compositional parameter change allows the binder to achieve adequate adhesion and interconnectivity in aqueous systems, countering the typical limitation of water-based PVDF compositions.
Solution Approach 2:
The patent creates a composite binder system combining PVDF copolymer with specific ratios of different monomer units, where the copolymer structure synergistically provides both water dispersibility and effective binding performance. This composite material approach enables aqueous formulation while maintaining the mechanical and electrical connectivity functions required for battery electrodes.
4Object-affected harmful factors
If NMP is replaced with other organic solvents, then toxicity is reduced, but PVDF solubility deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the PVDF polymer by incorporating a specific copolymer composition (5-20 mol% of a monomer unit with specific properties) that fundamentally alters the polymer's solubility characteristics. This parameter modification enables the binder to dissolve or disperse adequately in water, achieving both reduced toxicity and maintained solubility/stability.
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 solution provides a stable, non-toxic, and environmentally friendly aqueous slurry system for producing high-quality electrodes with excellent interconnectivity, ensuring effective performance in lithium ion secondary batteries while eliminating the risks associated with organic solvents.
Implementation Method 1
a stable, aqueous slurries have now been found for producing high quality electrodes for batteries and other electrical storage devices having interconnectivity. The slurry contains one or more fluoropolymers, preferably PVDF, powder electrode materials such as electrically active lithium metal compounds and carbonaceous material dispersed in aqueous medium with a (meth)acrylic polymer dispersant.
Implementation Method 2
a crosslinking agent comprising an aminoplast and/or a polycarbodiimides
Implementation Method 3
an organic diluent
Data Source
AI summary
An electrode binder of a lithium ion secondary battery comprising an aqueous dispersion of: (a) a polyvinylidene binder; (b) a (meth)acrylic polymer dispersant; (c) a crosslinking agent comprising an aminoplast and/or a polycarbodiimide; and (d) an organic diluent. The (meth)acrylic polymer dispersant is prepared from a mixture of monomers comprising one or more carboxylic acid group-containing (meth)acrylic monomers and one or more hydroxyl group-containing (meth)acrylic monomers, and carboxylic acid groups on the (meth)acrylic polymer dispersant are at least partially neutralized with a base. The binder can be used in the assembly of electrodes of lithium ion secondary batteries.