Lithium-Ion Electrode Binder Composition Without NMP Solvent

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Solution Overview

Problem

Current fluoropolymer binder compositions for electrodes in electrical storage devices rely on N-methyl-2-pyrrolidone (NMP) as a solvent, which is toxic and poses health and environmental concerns, necessitating the development of alternative solvent systems that maintain adhesion, interconnectivity, and durability while being environmentally friendly.

Innovation Solution

A binder composition comprising a fluoropolymer with constitutional units of vinylidene fluoride and (meth)acrylic polymers, combined with a trialkyl phosphate solvent, which provides improved adhesion and interconnectivity without the use of NMP, ensuring compatibility with existing manufacturing practices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If NMP is used as solvent, then adhesion and interconnectivity are improved, but health and environmental safety deteriorate

Engineering Contradiction:

ImproveadhesionVSAvoidtoxicity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameter of the solvent from NMP to a water-based system with specific surfactants and pH adjusters, maintaining adhesion properties while eliminating toxicity. The binder composition is modified to include carboxymethyl cellulose and other water-soluble polymers that provide similar binding functionality without the harmful effects of NMP.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs readily available, non-toxic materials such as water, carboxymethyl cellulose, and common surfactants that can be easily disposed of without environmental harm, replacing the persistent and toxic NMP solvent system.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If alternative solvents are used, then health and environmental safety are improved, but adhesion and interconnectivity may deteriorate

Engineering Contradiction:

ImprovetoxicityVSAvoidadhesion

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent creates a composite binder system combining water, carboxymethyl cellulose, surfactants, and pH adjusters that work synergistically to provide adhesion equivalent to or better than NMP, while maintaining non-toxicity. The combination of multiple components compensates for the lower inherent adhesion of individual water-based materials.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces surfactants as intermediary substances that mediate between the water-based solvent and the electrode materials, improving wetting and adhesion properties that would otherwise be insufficient with simple water solutions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If NMP is used as solvent, then interconnectivity is improved, but environmental compatibility deteriorates

Engineering Contradiction:

ImproveinterconnectivityVSAvoidenvironmental impact

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the solvent parameter from organic NMP to aqueous-based system, and modifies the binder composition parameters to include water-soluble polymers and surfactants, achieving interconnectivity through different chemical mechanisms that are environmentally benign.

Inventive Principle:

Principle #35Parameter changes

4Object-affected harmful factors

If binder composition is modified to eliminate NMP, then environmental safety is improved, but manufacturing compatibility may deteriorate

Engineering Contradiction:

ImprovetoxicityVSAvoidmanufacturing compatibility

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent adjusts the binder composition parameters to match the rheological and processing characteristics of conventional NMP-based slurries, including viscosity control through surfactant selection and concentration optimization, ensuring compatibility with existing manufacturing equipment and processes.

Inventive Principle:

Principle #35Parameter changes

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 achieves superior adhesion and interconnectivity in electrode compositions, enhancing the performance and safety of electrical storage devices by eliminating the use of toxic NMP and maintaining the necessary properties for electrode durability.

Implementation Method 1

the organic solvent of choice is N-methyl-2-pyrrolidone (NMP). PVDF binders dissolved in NMP provide superior adhesion

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

the electrode material is combined with the solution to form a slurry that is applied to a metal foil or mesh to form the electrode

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS20240170676A1Electrode binder and slurry compositions for lithium ion electrical storage devices

Publication Date: 2024.05.23 PPG INDUSTRIES OHIO INC

AI summary

The present disclosure provides a binder composition comprising (a) at least one fluoropolymer comprising the residue of vinylidene fluoride; (b) one or more (meth)acrylic polymers; and (c) an organic medium comprising a trialkyl phosphate solvent. Also disclosed are slurry compositions, electrodes, and electrical storage devices.