Congratulations to Shanghai Jiao Tong University for successfully using the Luxiangyi centrifuge to separate graphene!

Finally, the teacher told us on-site that the experimental results obtained after centrifugation were perfect. The clear liquid in the beaker is the graphene we needed.

The currently known material properties and application areas of graphene.

What is graphene?

Graphene It is a new two-dimensional carbon material consisting of carbon atoms connected by large π-bonds in a honeycomb-like lattice structure, and it belongs to an allotrope of carbon. In 2004, it was discovered by Kostya Novoselov and Andre Geim at the University of Manchester through repeated mechanical exfoliation of graphite using adhesive tape. In the graphene structure, each carbon atom contributes one unbound electron, which forms a planar hexagonal arrangement with neighboring carbon atoms via sp² hybridization, resulting in a highly stable structure with a nearly perfect two-dimensional crystalline configuration. It is the thinnest, strongest, and has the lowest resistivity among all known materials in the world.

Graphene materials are classified into single-layer graphene, bilayer graphene, few-layer graphene (3–10 layers), and multilayer graphene (more than 10 layers). Graphene is generally characterized by... Layered form By deforming graphene into certain shapes—such as spherical, tubular, and multi-layered forms—we obtain the well-known fullerenes (C60), carbon nanotubes, and graphite.

Performance characteristics of graphene

1. The thinnest material (high light transmittance): The thickness of a single-layer graphene is just one carbon atom—about one two-hundred-thousandth the diameter of a human hair. As a result, single-layer graphene is nearly transparent and invisible to the naked eye, with a light transmittance as high as... 97.7% 。

2. The hardest materials (high strength and modulus): Its tensile strength and elastic modulus can reach 125 GPa and 1.1 TPa, respectively. If we extrapolate the strength of steel based on graphene thickness, the ideal strength of graphene material would be approximately that of steel. 100 It is also highly durable—indeed, even harder than diamond. At the same time, it boasts excellent flexibility and can be bent at will. In terms of mechanical properties, graphene materials achieve a perfect balance of high strength, high hardness, and flexibility.

3. The most conductive material (low resistivity): Each carbon atom in graphene is... SP2 Hybridization and contributes one p-orbital electron to form a large π-bond; the π-electrons can move freely, endowing graphene with exceptional electrical conductivity. Electrons in graphene experience minimal scattering during transport, and their mobility can reach as high as 2 × 10⁵ cm²/(V·s)—about ten times that of electrons in silicon. 140 Twice.

4. The most thermally conductive material (high thermal conductivity): The thermal conductivity of single-layer graphene reaches as high as 5,300 W/m·K, whereas copper—a heat-dissipating metal widely used in industry—has a thermal conductivity of only 400 W/m·K. However, as the number of graphene layers increases, its thermal conductivity gradually decreases.

Graphene production methods

There are many methods for producing graphene, which can be broadly categorized into two major types: physical methods and chemical methods. Physical methods generally involve... Mechanical exfoliation , which was the original method used when graphene was first discovered. However, this approach couldn't achieve mass production, so a series of chemical methods subsequently emerged. Chemical methods generally include: Gas-phase deposition method (CVD), Epitaxial growth method and Redox method 。

1. Mechanical exfoliation method: The most primitive synthesis method involves repeatedly peeling off the two sides of a graphite flake using adhesive tape to obtain graphene. Although this method is simple, the resulting graphene typically measures from several micrometers to tens of micrometers in size.

2. Chemical Vapor Deposition: Organic gases are adsorbed onto catalytically active metal or nonmetal surfaces, and upon heating, the organic gases undergo dehydrogenation to form graphene on the substrate surface.

3. Epitaxial Growth Method: A method for growing graphene crystals on the SiC crystal structure via lattice matching. The principle behind this method involves heating single-crystal SiC under ultra-low pressure, high vacuum, and high temperature, during which silicon atoms are removed, allowing carbon atoms to reorganize and form graphene layers.

4. Redox method: Graphite is oxidized to modify the free electron pairs on its graphite layers and to functionalize its surface with oxygen-containing groups, thereby enhancing its hydrophilicity. The oxidized graphite is then exfoliated in water to form a uniform and stable colloidal dispersion of oxidized graphene. Finally, chemical reduction, thermal reduction, and catalytic reduction methods are employed to reduce the oxidized graphite back into graphene.

Comparison of the advantages and disadvantages of various graphene production methods:

In recent years, the graphene industry has attracted worldwide attention, yet its overall application volume remains relatively small, and there is still a need to develop large-scale market demand. Currently, most graphene applications are still confined to the laboratory stage. Although graphene performs exceptionally well in laboratory settings, its product stability remains to be verified if scaled-up production is undertaken. Moreover, downstream applications of graphene have yet to achieve widespread adoption.

Development and Application Status of Graphene Technology in the Automotive Field

1. Automotive lightweight materials

Graphene material has a strength 100 times that of steel and possesses high... Intensity and Hardness However, due to its lower density and lighter weight, graphene is an ideal material for automotive lightweighting. Lightweight composite materials reinforced with graphene can be used as body materials for automobiles. Recently, the Liverpool-based Briggs Automotive Company has incorporated graphene into the body of its brand’s BAC MONO single-seater sports car, which has already passed road tests.

2. High-wear-resistant materials for automobiles

In addition to serving as a body material, graphene composites can also be applied in the automotive components sector—for example, in automobile tires. Adding graphene materials to car tires can make them more... Wear-resistant It is puncture-resistant and can significantly extend the service life. The State Key Laboratory of Polymer Materials Engineering at Sichuan University has independently developed the world’s first graphene-enhanced rubber tire. During Premier Li Keqiang’s inspection tour of Sichuan, this tire even received a “meeting” with the Premier himself.

3. High-thermal-conductivity composite material

Graphene boasts a thermal conductivity as high as 5,300 W/m·K. When combined with highly thermally conductive polymers, it can produce high-quality composite materials that are strong, electrically and thermally conductive, and lightweight. The ultra-two-dimensional nanostructure of graphene ensures uniform heat distribution within the heated area, making it suitable for use in automotive heated seat materials.

4 Automotive anti-corrosion coating materials

Graphene boasts high chemical stability, a hydrophobic surface, and resistance to acid and alkali corrosion. Studies have shown that when graphene is sprayed onto steel surfaces and immersed in seawater, the coated steel can remain rust-free for up to a month—far longer than the few days typically achieved by conventional high-performance coatings. Thanks to graphene’s exceptional hydrophobicity and its unique nanostructure, it can be applied to automotive coatings to significantly enhance their anti-corrosion performance.

5. Conductive Functional Materials for Automotive Applications

In automotive fuel supply systems, fuel flowing in a rapid turbulent manner can generate static electricity. Therefore, components of the fuel supply system—including fuel tanks, fuel line fittings, filters, and others—must have sufficient conductivity to prevent static charge buildup and eliminate hazards such as sparks and explosions. Currently, conductive plastics reinforced with carbon nanotubes have been successfully applied in automotive fuel supply systems. Graphene boasts electrical conductivity comparable to that of carbon nanotubes, yet its production cost is lower, making it an ideal candidate for use in conductive functional plastics. Conductive functional plastics based on graphene can also be used in automotive components such as fenders, door handles, and mirror housings, facilitating electrostatic painting of vehicle bodies and eliminating the need for surface conductivity treatment—a step typically required before electrostatic painting when using non-conductive plastics.

6. Electric vehicle energy storage materials

The power battery is the heart of new-energy vehicles. Although the country is currently vigorously promoting electric vehicles, shortcomings such as short driving range and long charging times continue to hinder their market penetration. At present, the primary energy storage devices used as power sources include lithium-ion power batteries, supercapacitors, and fuel cells. All three types require electrode materials with large specific surface areas, high electrical conductivity, and excellent electrochemical stability—providing graphene with extensive application potential.

( 1 Lithium battery electrode materials

Graphene has three main applications in lithium batteries:

· Used as a conductive additive in positive and negative electrode materials;

· As a functional coating on copper foil or aluminum foil;

· Used as an electrode material in negative electrode materials.

When materials such as Si and Sn are used as battery anodes, a significant challenge is the high volume expansion rate during charge and discharge cycles—often reaching as much as 400%. This expansion can lead to electrode pulverization or rapid degradation of battery capacity. Coating these nanomaterials with graphene can effectively address the issue of volume expansion. The figure below illustrates several applications of graphene as a lithium-ion electrode material:

( 2 Super capacitor

Supercapacitors are a new type of energy-storage device. Compared with rechargeable batteries, they can be charged without current limitations, resulting in extremely fast charge-discharge rates—often completing the entire process within just a few seconds. Additionally, supercapacitors boast high power output and long service life. After being dispersed, graphene exhibits exceptionally high energy-storage activity, thanks to its theoretical specific surface area of up to 2,630 m²/g. Consequently, graphene-based composites are well-suited for use in the field of supercapacitors.

( 3 Fuel cell

In low-temperature fuel cell applications, both the oxidation reaction at the anode and the reduction reaction at the cathode require precious metals such as Pt and Pd as catalysts, significantly increasing the cost of fuel cells. By supporting these precious metals on graphene, on the one hand, the strong π-conjugation in graphene can effectively inhibit the migration and aggregation of metal particles, thereby enhancing the stability of the catalyst. On the other hand, graphene’s excellent electrical conductivity can also reduce the internal resistance of the battery and improve its overall conductive performance.

Graphene boasts exceptional performance in many aspects, unmatched by other materials. In theory, all these potential industrial applications of graphene are entirely feasible. However, as a carbon material with a unique crystal structure, graphene has a hydrophobic surface and lacks active functional groups, meaning it has no readily available reactive chemical bonds and exhibits poor compatibility with other substances. These characteristics pose significant challenges to graphene’s application in the materials field. Thus, there is still a long way to go in research aimed at overcoming these difficulties and realizing the industrial-scale application of graphene.