Positive Electrode Mixture With Water-Controlled Binder Viscosity

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Solution Overview

Problem

Existing positive electrode mixtures experience increased viscosity when using specific binders, leading to instability and difficulty in forming a homogeneous electrode layer.

Innovation Solution

Incorporating a fluorine-containing polymer and copolymer with controlled water content (200 to 10,000 ppm) into the positive electrode mixture, along with a non-aqueous solvent, to maintain viscosity and enhance adhesiveness to the current collector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a fluorine-containing polymer and copolymer are used as binders in the positive electrode mixture, then adhesiveness to the current collector is improved, but viscosity of the mixture increases

Engineering Contradiction:

ImproveadhesivenessVSAvoidviscosity increase

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the water content in the non-aqueous solvent to within 200 to 10,000 ppm. This parameter control modifies the physical state of the binder components, allowing them to maintain low viscosity while preserving their adhesive properties. The controlled water content prevents excessive thickening of the mixture that would otherwise occur with fluorine-containing polymers.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite binder system comprising both a fluorine-containing polymer (A) and a fluorine-containing copolymer (B) with specific compositional ratios. This composite approach allows the materials to work synergistically, where the copolymer modifies the viscosity characteristics while the polymer provides adhesion, achieving both low viscosity and high adhesiveness simultaneously.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If water content is increased to control viscosity, then viscosity stability is improved, but adhesiveness may be compromised

Engineering Contradiction:

Improveviscosity stabilityVSAvoidadhesiveness

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent identifies and controls the water content parameter within the optimal range of 200 to 10,000 ppm in the non-aqueous solvent. This precise parameter control achieves viscosity stability without compromising adhesiveness, as the controlled water content provides sufficient lubrication and flow characteristics while maintaining the binder's adhesive functionality.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4693455A1Positive electrode mixture, positive electrode, and secondary battery

Publication Date: 2026.02.11 DAIKIN INDUSTRIES LTD

AI summary

The present disclosure provides a positive electrode mixture comprising a fluorine-containing polymer (A), a fluorine-containing copolymer (B), a positive electrode active material (C), a non-aqueous solvent (D), and water (E), wherein the fluorine-containing polymer (A) contains vinylidene fluoride unit and a monomer unit derived from a monomer (1): CR1R2=CR3-R4CO2Y1, wherein the fluorine-containing copolymer (B) contains vinylidene fluoride unit and a perfluoromonomer unit, wherein the positive electrode active material (C) is a positive electrode active material represented by the general formula (C): LiyNi1-xMxO2, and wherein a content of the water (E) is 200 to 10,000 ppm by mass based on a mass of the non-aqueous solvent (D).