PVDF Electrode Binder Slurry for Stable NMP-Free Adhesion

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Solution Overview

Problem

The electronics industry faces challenges in producing smaller devices with smaller batteries due to the need for alternative solvents to N-methyl-2-pyrrolidone (NMP) for polyvinylidene fluoride (PVDF) binders, as NMP is toxic and poses health and environmental issues, while other solvents fail to provide stability, adhesion, and interconnectivity in electrode compositions.

Innovation Solution

A slurry composition using a fluoropolymer dispersed in a liquid medium, specifically polyvinylidene fluoride (PVDF) with an addition polymer containing constitutional units from heterocyclic group-containing ethylenically unsaturated monomers, which forms a stable and adhesive film on electrodes, replacing NMP and ensuring interconnectivity without moisture attraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If NMP is used as solvent for PVDF binder, then adhesion and interconnectivity are improved, but health and environmental issues worsen

Engineering Contradiction:

ImproveadhesionVSAvoidtoxicity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a two-component binder system where PVDF provides the primary binding function and a secondary polymer component acts as an intermediary to enhance adhesion and interconnectivity. This combination allows replacement of NMP with alternative solvents while maintaining electrode performance, as the secondary polymer compensates for the reduced solvent effectiveness.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention employs a composite binder system combining PVDF with another polymer material. This composite approach creates synergistic effects where the combined binder system achieves superior adhesion and interconnectivity properties that neither component alone could provide, enabling elimination of toxic NMP solvent.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If alternative solvents are used instead of NMP, then health and environmental issues are improved, but stability and adhesion worsen

Engineering Contradiction:

ImprovetoxicityVSAvoidstability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The secondary polymer component serves as an intermediary that bridges the gap between alternative solvents and PVDF binder. It mediates the interaction to ensure proper dispersion, stability, and adhesion, compensating for the inferior solvent properties compared to NMP.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the binder system parameters by introducing a second polymer component with specific properties (molecular weight, functional groups, compatibility). These parameter changes enable the system to achieve desired stability and adhesion when using alternative solvents, effectively tuning the system performance.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If PVDF is dispersed in alternative organic solvents, then toxicity is reduced, but dispersion stability and slurry viscosity worsen

Engineering Contradiction:

ImprovetoxicityVSAvoiddispersion stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The alternative polymer component acts as a dispersing intermediary that improves the compatibility between PVDF and alternative solvents. It facilitates stable dispersion by reducing aggregation and improving wetting, addressing the poor dispersion stability inherent in alternative solvent systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The composite binder system creates a more robust dispersion structure where the two polymer components work together to maintain stability. The secondary polymer provides additional interaction sites and improves overall compatibility with alternative solvents, enhancing dispersion stability.

Inventive Principle:

Principle #40Composite materials

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 stable and high-quality electrodes with improved adhesion and interconnectivity, ensuring effective performance in electrical storage devices while being environmentally friendly by eliminating the use of toxic NMP.

Implementation Method 1

PVDF binders dissolved in NMP provide superior adhesion and an interconnectivity of all the active ingredients in the electrode composition. The bound ingredients are able to tolerate large volume expansion and contraction during charge and discharge cycles without losing interconnectivity within the electrodes.

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS11843118B2Electrode binder slurry composition for lithium ion electrical storage devices

Publication Date: 2023.12.12 PPG INDUSTRIES OHIO INC

AI summary

The present invention provides a slurry composition comprising: (a) an electrochemically active material and/or an electrically conductive agent; and (b) a binder comprising: (i) a polymer comprising a fluoropolymer dispersed in a liquid medium; and (ii) a polymer comprising an addition polymer comprising constitutional units comprising the residue of a heterocyclic group-containing ethylenically unsaturated monomer. The present invention also provides electrodes and electrical storage devices.