Polyacrylic Acid Binder Crosslinked with Polyfunctional Amine

Solution Overview

Problem

Existing polymer compounds used as binders for negative electrodes in power storage devices, such as rechargeable batteries, face challenges in maintaining cycle properties and adhesion when the weight-average molecular weight decreases, particularly when using polyacrylic acid with low molecular weights.

Innovation Solution

A polymer compound formed by condensation of polyacrylic acid and a polyfunctional amine with a specific molecular structure, represented by general formula (1), which includes a crosslinked structure connecting carboxylic acid side chains, is used as a binder for negative electrodes, maintaining cycle properties and adhesion even with low molecular weight polyacrylic acid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If polyacrylic acid with low molecular weight is used as a binder, then cost is reduced and processing is easier, but cycle properties and adhesion deteriorate

Engineering Contradiction:

Improveprocessing easeVSAvoidcycle property

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent creates a composite polymer compound by combining polyacrylic acid with a polyfunctional amine (having 3 or more amino groups) through condensation reaction. This forms a crosslinked structure where the polyfunctional amine acts as a bridge between polyacrylic acid chains, creating a three-dimensional network. This composite structure allows the use of low molecular weight polyacrylic acid while maintaining adhesion and cycle properties, as the crosslinked network provides structural integrity that compensates for the lower molecular weight of the base polymer.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the molecular structure parameter of the amine component by selecting polyfunctional amines with 3 or more amino groups (such as melamine, diaminodiphenyl sulfone, or triaminotriphenyl methane). This structural parameter change creates a crosslinked network that fundamentally alters the physical properties of the binder system, enabling low molecular weight polyacrylic acid to achieve high adhesion and cycle stability that would normally require high molecular weight polymers.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If polyacrylic acid with low molecular weight is used as a binder, then viscosity is reduced and coating is easier, but adhesion strength deteriorates

Engineering Contradiction:

Improvecoating easeVSAvoidadhesion strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent creates a composite polymer compound by combining polyacrylic acid with a polyfunctional amine (having 3 or more amino groups) through condensation reaction. This forms a crosslinked structure where the polyfunctional amine acts as a bridge between polyacrylic acid chains, creating a three-dimensional network. This composite structure allows the use of low molecular weight polyacrylic acid while maintaining adhesion and cycle properties, as the crosslinked network provides structural integrity that compensates for the lower molecular weight of the base polymer.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the molecular structure parameter of the amine component by selecting polyfunctional amines with 3 or more amino groups (such as melamine, diaminodiphenyl sulfone, or triaminotriphenyl methane). This structural parameter change creates a crosslinked network that fundamentally alters the physical properties of the binder system, enabling low molecular weight polyacrylic acid to achieve high adhesion and cycle stability that would normally require high molecular weight polymers.

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 polymer compound improves the cycle property and initial efficiency of power storage devices by maintaining adhesion of the negative electrode active substance layer, with a blend proportion of polyfunctional amine to carboxyl groups within a specific ratio, enhancing the battery characteristics.

Implementation Method 1

a polymer compound formed by condensation of a polyacrylic acid and a polyfunctional amine

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS10875964B2Polymeric binder of polyacrylic acid, polyfunctional amine, and linking benzene ring

Publication Date: 2020.12.29 TOYOTA INDUSTRIES CORP

AI summary

A polymer compound to be used as a binder for a negative electrode of a power storage device is provided. The polymer compound is formed by condensation of a polyacrylic acid and a polyfunctional amine represented by the following general formula (1), where X is a ring structure having 1 to 3 benzene rings; and C1 to C4 are each a carbon atom constituting a benzene ring in the ring structure.