Carbon Nanotube Dispersion for Battery Slurry Cycle Stability

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Solution Overview

Problem

The carbon nanotube dispersion liquid for electrode slurries in existing technologies has limitations in charge-discharge cycle characteristics due to low G/D ratio and lack of consideration for frequency distribution, leading to aggregation and reduced dispersibility of carbon nanotubes.

Innovation Solution

A carbon nanotube dispersion liquid with carbon nanotubes having a diameter of 0.4 to 2 nm, a G/D ratio of 50 to 200, and a specific particle size distribution, combined with a dispersant and dispersion medium, is used to enhance dispersibility and electrical connectivity in electrode slurries, thereby improving charge-discharge cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbon nanotubes are used as a conductive agent to improve conductivity, then conductivity is improved, but dispersibility deteriorates due to aggregation

Engineering Contradiction:

ImproveconductivityVSAvoiddispersibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the physical and chemical parameters of carbon nanotubes, specifically controlling the G/D ratio to be 50-200 and diameter to be 0.4-2 nm, to achieve optimal balance between conductivity and dispersibility. This parameter optimization prevents aggregation while maintaining conductive performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a dispersant as an intermediary substance between carbon nanotubes and the electrode slurry components. The dispersant acts as a mediator that prevents carbon nanotube aggregation and maintains uniform distribution, thereby preserving both conductivity and dispersibility

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If carbon nanotubes with low G/D ratio are used, then dispersibility is improved, but charge-discharge cycle characteristics deteriorate

Engineering Contradiction:

ImprovedispersibilityVSAvoidcharge-discharge cycle characteristics

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent optimizes the G/D ratio parameter to a specific range of 50-200, which represents a balanced state that prevents both aggregation and maintains charge-discharge cycle characteristics. This parameter control resolves the contradiction by identifying the optimal range that satisfies both requirements

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If carbon nanotubes are dispersed without considering particle size distribution, then manufacturing is simplified, but charge-discharge cycle characteristics deteriorate

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcharge-discharge cycle characteristics

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent specifies a diameter parameter range of 0.4-2 nm for carbon nanotubes, which optimizes both charge-discharge cycle characteristics and manufacturing feasibility. This parameter specification provides clear manufacturing guidance while ensuring performance requirements are met

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 solution effectively suppresses the deterioration of charge-discharge cycle characteristics in batteries by maintaining the fibrous state of carbon nanotubes and preventing active material isolation, leading to improved conductivity and capacity maintenance.

Implementation Method 1

a dispersant... the carbon nanotubes... are likely to aggregate, and therefore have a problem of dispersibility

Methodology Applied

Scientific EffectSteric repulsion:

Implementation Method 2

a dispersant... carbon nanotubes... dispersibility

Methodology Applied

Scientific EffectElectrostatic repulsion:

Implementation Method 3

a volume-based particle size distribution obtained by a laser diffraction method

Methodology Applied

Scientific EffectLaser diffraction: Diffraction

Implementation Method 4

a G/D ratio, which is a ratio of a peak intensity of a G-band... to a peak intensity of a D-band... in a Raman spectrum

Methodology Applied

Scientific EffectRaman scattering:

Data Source

PatentUS20240105958A1Carbon nanotube dispersion liquid for electrode slurry, negative electrode slurry, nonaqueous electrolyte secondary battery, and manufacturing method for carbon nanotube dispersion liquid for electrode slurry

Publication Date: 2024.03.28 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

Provided is a carbon nanotube dispersion liquid for an electrode slurry such that it is possible to inhibit a decrease in a charge-discharge cycle characteristic. A carbon nanotube dispersion liquid for an electrode slurry according to one aspect of the present disclosure includes carbon nanotubes having a diameter of 0.4 to 2 nm, a dispersant, and a dispersion medium. In a Raman spectroscopy spectrum, the carbon nanotubes have a G/D ratio, which is the ratio of the peak intensities of the G-band (1560 to 1600 cm−1) and the D-band (1310 to 1350 cm−1), within the range of 50 to 200, and in a volume-based particle size distribution via a laser diffraction method, the carbon nanotubes have 3 to 5 peaks, and if the peaks are, from the small particle diameter side, P1, P2, . . . , Pn, the greatest frequency peak is in the range pf P2 to Pn-1.