Carbon Black Dispersion Composition for Stable Li-Ion Cathode Paste

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Solution Overview

Problem

Lithium-ion secondary battery positive electrodes face challenges in achieving uniform dispersion of high specific surface area conductive additives like carbon black, leading to increased internal resistance and reduced battery life due to agglomeration and poor shelf stability of dispersions, which existing methods struggle to address efficiently and cost-effectively.

Innovation Solution

A carbon black dispersion composition using N-methyl-2-pyrrolidone as the dispersing medium, combined with a hindered phenolic compound as a radical scavenger, enhances dispersibility and shelf stability without requiring extensive time or effort, comprising carbon black, a dispersant, and a hindered phenolic compound within specific concentration ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbon black with higher specific surface area and higher structuring is used to increase conductivity, then conductivity is improved, but dispersibility deteriorates due to greater tendency to agglomerate

Engineering Contradiction:

ImproveconductivityVSAvoiddispersibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

A hindered phenolic compound is introduced as an intermediary substance between carbon black particles and the dispersing medium. This compound adsorbs onto the carbon black surface, providing steric hindrance that prevents particle aggregation while maintaining the high specific surface area carbon black's conductivity properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical parameters of the dispersion system by introducing the hindered phenolic compound, which modifies the surface properties of carbon black particles. This parameter change enables the system to maintain both high conductivity (from high surface area carbon black) and good dispersibility (from surface modification).

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If polymeric dispersant is used to achieve uniform dispersion of carbon black, then dispersibility is improved, but shelf stability deteriorates due to viscosity changes and agglomeration during storage

Engineering Contradiction:

ImprovedispersibilityVSAvoidshelf stability

Core Design Contradiction:

Stability of the object's compositionVSDuration of action of stationary object

Solution Approach 1:

The patent replaces long-chain polymeric dispersants with small molecule hindered phenolic compounds that act as effective dispersants. These smaller molecules provide sufficient steric hindrance without creating the viscosity and stability issues associated with polymeric dispersants during storage.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention extracts the essential dispersing function from complex polymeric dispersants and implements it through simpler hindered phenolic compounds. This extraction of the core dispersing mechanism eliminates the storage stability problems while maintaining dispersibility.

Inventive Principle:

Principle #2Taking out (Extraction)

3Stability of the object's composition

If additional acidic compounds are added to increase dispersibility, then dispersibility is improved, but chemical modification of electrode mixture composition occurs

Engineering Contradiction:

ImprovedispersibilityVSAvoidchemical modification

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

Instead of using acidic compounds that can cause harmful chemical modifications, the patent employs hindered phenolic compounds that provide dispersing benefits without the harmful chemical side effects. The phenolic hydroxyl groups provide surface attachment while the hindered structure prevents unwanted reactions with electrode materials.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 excellent carbon black dispersibility and shelf stability, reducing defective production rates and manufacturing costs for lithium-ion secondary batteries by maintaining uniform dispersion and viscosity, thereby improving battery performance and longevity.

Implementation Method 1

a hindered phenolic compound within specific concentration ranges... which functions as a radical scavenger is effective for enhancing the dispersibility of carbon black within the dispersion and the long-term shelf stability

Methodology Applied

Scientific EffectRadical scavenging: Oxidation

Implementation Method 2

N-methyl-2-pyrrolidone as the dispersing medium... increases the dispersibility of the carbon black, continues to maintain the dispersibility immediately after dispersion, and imparts an excellent shelf stability

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentEP4300634A1Carbon black dispersion composition for battery, mixture paste for positive electrode, positive electrode for lithium-ion secondary battery, and lithium-ion secondary battery

Publication Date: 2024.01.03 SHIN ETSU CHEMICAL CO LTD

AI summary

A carbon black dispersion composition for batteries contains carbon black, a dispersant, N-methyl-2-pyrrolidone, and from 0.0001 to 5 parts by weight of a hindered phenolic compound per 100 parts by weight of carbon black. The composition uses as the dispersing medium N-methyl-2-pyrrolidone, which increases the dispersibility of the carbon black, continues to maintain the dispersibility immediately after dispersion and provides an excellent shelf stability without expenditure of time and effort.