Application And Mechanism Study of Ultrasonic Technology in Graphene Dispersion

Graphene has shown broad application prospects in the fields of energy, electronics, composite materials, etc. due to its excellent mechanical, electrical and thermal properties. However, the strong van der Waals force and π-π interaction between graphene sheets easily lead to their aggregation, which seriously affects their performance. Ultrasonic dispersion technology, as an efficient and environmentally friendly physical dispersion method, has significant advantages in solving the problem of graphene agglomeration. This paper systematically discusses the mechanism of ultrasonic dispersion of graphene, the optimization of key parameters and its application progress.

The core of ultrasonic dispersion technology is to use the cavitation effect produced by high-frequency sound waves (usually 20 kHz-1 MHz) in liquids. When ultrasound acts on graphene suspensions, tiny bubbles in the liquid expand rapidly and collapse violently under the action of sound pressure, instantly generating local high temperature (about 5000 K), high pressure (about 1000 atm) and high-speed microjets. This extreme physical environment can effectively overcome the interaction force between graphene sheets, peel off aggregates and achieve uniform dispersion of single-layer or few-layer graphene.

1. Key factors affecting ultrasonic dispersion

1.1 Ultrasonic power and time

Low power and short time: may lead to incomplete dispersion and uneven thickness of the flakes.

High power and long time: may destroy the graphene structure, produce defects or fragmentation.

Optimization strategy: Gradient power method is usually used (such as high power to break up agglomerates first, and then low power to maintain the dispersed state).

1.2 Solvent selection

Polar solvents (such as NMP and DMF) can stabilize the dispersion state of graphene through intermolecular forces.

The addition of surfactants (such as SDS and PVP) can reduce surface tension and assist ultrasonic dispersion.

1.3 Temperature control

The heat generated by the ultrasonic process may accelerate solvent volatilization or induce graphene oxidation, and a cooling system (water bath/ice bath) is required to maintain the system temperature.

2. Application progress of ultrasonic dispersion technology

2.1 Preparation of graphene composite materials

Polymer-based composite materials: Graphene dispersed by ultrasound can be evenly embedded in epoxy resin, rubber and other matrices to improve the conductivity of materials (such as antistatic coatings) and mechanical strength (such as aviation materials).

Metal-based composite materials: Graphene/copper composite materials are prepared by ultrasound-assisted electrodeposition technology, and the thermal conductivity is increased by more than 40%.

2.2 Energy storage field

Lithium-ion battery: Ultrasonic dispersed graphene as a conductive additive can increase the specific capacity of electrode materials by 20%~30%.

Supercapacitor: Preparation of three-dimensional porous graphene structure, specific surface area of 2600 m²/g, and significantly improved power density.

2.3 Biomedical application

Ultrasound-assisted preparation of graphene quantum dots (GQDs), with a particle size controlled at 3–5 nm, can be used for targeted drug carriers or bioimaging.