Battery Separator Coating Slurry for Dispersion and Adhesion

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Solution Overview

Problem

Existing slurry compositions for secondary battery separators face challenges with particle agglomeration and reduced adhesion to the substrate, leading to deteriorated battery performance during charging and discharging.

Innovation Solution

A slurry composition incorporating a phenolic compound with two or more aromatic rings, inorganic particles, a binder, and a solvent, where the phenolic compound is used in specific weight ratios to enhance dispersibility and adhesion, preventing particle agglomeration and improving substrate attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a carboxylic acid-based dispersant or phosphoric acid-based dispersant is added to improve dispersibility, then the dispersibility of inorganic particles is improved, but the adhesion between the coating layer and substrate deteriorates during charging and discharging

Engineering Contradiction:
Improvedispersibility of inorganic particlesVSAvoidadhesion between coating layer and substrate
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the dispersant by selecting a polyacrylonitrile-based polymer with specific molecular weight (10,000-1,000,000) and cyanogen content (15-30%). This parameter optimization allows the dispersant to maintain effective particle dispersion while minimizing adverse effects on substrate adhesion during battery operation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite approach by combining the polyacrylonitrile-based dispersant with a specific binder (polyvinylidene fluoride or carboxymethyl cellulose sodium salt) in optimized weight ratios. This composite formulation achieves synergistic effects where the dispersant ensures particle dispersion and the binder ensures strong adhesion to the substrate, resolving the contradiction between dispersibility and adhesion

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If inorganic particles are not properly dispersed in the slurry composition, then the coating uniformity is poor, but adding conventional dispersants improves dispersibility while reducing adhesion

Engineering Contradiction:
Improvecoating uniformityVSAvoidadhesion between coating layer and substrate
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent optimizes the molecular weight parameter of the polyacrylonitrile-based dispersant (10,000-1,000,000) and cyanogen content (15-30%), which enables effective steric hindrance for particle separation without excessive interaction with the substrate that would compromise adhesion, thereby achieving both coating uniformity and reliable adhesion

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The polyacrylonitrile-based dispersant acts as an intermediary between inorganic particles and the substrate. It provides steric hindrance to prevent particle agglomeration and coating defects while its optimized chemical structure minimizes interference with the binder-substrate adhesion mechanism, thus serving as an effective mediator that resolves the contradiction between coating uniformity and adhesion

Inventive Principle:
Principle #24Intermediary (Mediator)

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 excellent dispersibility and adhesion, resulting in improved mechanical properties and prolonged battery lifespan by reducing de-intercalation of inorganic particles during charging and discharging.

Implementation Method 1

the inorganic particles contained in the slurry composition are not properly dispersed, the inorganic particles may agglomerated together

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

excellent adhesion to a separator substrate

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3696879B1Slurry composition for coating secondary battery separator and secondary battery separator using the same
Publication Date: 2024.03.20 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to a slurry composition for coating a secondary battery separator, a separator prepared using the same, and a secondary battery including the separator, wherein the slurry composition includes a phenolic compound including two or more aromatic rings, inorganic particles, a binder, and a solvent.