Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018

Researchers at Chalmers University of Technology, Sweden, have developed a graphene assembled film that has over 60 percent higher thermal conductivity than graphite film - despite the fact that graphite simply consists of many layers of graphene. The graphene film shows great potential as a novel heat spreading material for form-factor driven electronics and other high power-driven systems.

Until now, scientists in the graphene research community have assumed that graphene assembled film cannot have higher thermal conductivity than graphite film. Single layer graphene has a thermal conductivity between 3500 and 5000 W/mK. If you put two graphene layers together, then it theoretically becomes graphite, as graphene is only one layer of graphite.


In the graphene film, phonons -- quantum particles that describe thermal conductivity -- can move faster in the graphene layers rather than interact between the layers, thereby leading to higher thermal conductivity.

Credit: Chalmers University of Technology/Krantz Nanoart

Today, graphite films, which are practically useful for heat dissipation and spreading in mobile phones and other power devices, have a thermal conductivity of up to 1950 W/mK. Therefore, the graphene-assembled film should not have higher thermal conductivity than this.

Research scientists at Chalmers University of Technology have recently changed this situation. They discovered that the thermal conductivity of graphene assembled film can reach up to 3200 W/mK, which is over 60 percent higher than the best graphite films.

Professor Johan Liu and his research team have done this through careful control of both grain size and the stacking orders of graphene layers. The high thermal conductivity is a result of large grain size, high flatness, and weak interlayer binding energy of the graphene layers. With these important features, phonons, whose movement and vibration determine the thermal performance, can move faster in the graphene layers rather than interact between the layers, thereby leading to higher thermal conductivity.

"This is indeed a great scientific break-through, and it can have a large impact on the transformation of the existing graphite film manufacturing industry", says Johan Liu.

Furthermore, the researchers discovered that the graphene film has almost three times higher mechanical tensile strength than graphite film, reaching 70 MPa.

"With the advantages of ultra-high thermal conductivity, and thin, flexible, and robust structures, the developed graphene film shows great potential as a novel heat spreading material for thermal management of form-factor driven electronics and other high power-driven systems", says Johan Liu.

As a consequence of never-ending miniaturisation and integration, the performance and reliability of modern electronic devices and many other high-power systems are greatly threatened by severe thermal dissipation issues.

"To address the problem, heat spreading materials must get better properties when it comes to thermal conductivity, thickness, flexibility and robustness, to match the complex and highly integrated nature of power systems", says Johan Liu. "Commercially available thermal conductivity materials, like copper, aluminum, and artificial graphite film, will no longer meet and satisfy these demands."

The IP of the high-quality manufacturing process for the graphene film belongs to SHT Smart High Tech AB, a spin-off company from Chalmers, which is going to focus on the commercialisation of the technology.

###

More about: The research

The work has been done in collaboration with research teams at Uppsala University and SHT Smart High Tech AB in Sweden, Shanghai and Tongji University in China and University of Colorado Boulder in USA.

The paper "Tailoring the Thermal and Mechanical Properties of Graphene Film by Structural Engineering" is published online in the well-known scientific journal Small: https://onlinelibrary.wiley.com/doi/full/10.1002/smll.201801346

More about the graphene film:

The manufacturing method of the graphene film is based on simultaneous graphene oxide film formation and reduction, on aluminum substrate, dry-bubbling film separation, followed by high-temperature treatment as well as mechanical pressing. These conditions enable the formation of the graphene film with large grain size, good atomic alignment, thin-film structure, and low interlayer binding energy. All these features have great benefit for the transfer of both high-frequency diffusive phonons and low-frequency ballistic phonons, and thereby lead to the improvement of in-plane thermal conductivity of the graphene film. Phonons are quantum particles that describe the thermal conductivity of a material.

Media Contact

Johanna Wilde
johanna.wilde@chalmers.se
46-317-722-029

 @chalmersuniv

http://www.chalmers.se/en/ 

Johanna Wilde | EurekAlert!
Further information:
https://www.chalmers.se/en/departments/mc2/news/Pages/Graphene-assembled-film-shows-higher-thermal-conductivity-than-graphite-film.aspx
http://dx.doi.org/10.1002/smll.201801346

More articles from Materials Sciences:

nachricht Large-scale window material developed for PM2.5 capture and light tuning
18.02.2019 | University of Science and Technology of China

nachricht Engineered metasurfaces reflect waves in unusual directions
18.02.2019 | Aalto University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: (Re)solving the jet/cocoon riddle of a gravitational wave event

An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has combined radio telescopes from five continents to prove the existence of a narrow stream of material, a so-called jet, emerging from the only gravitational wave event involving two neutron stars observed so far. With its high sensitivity and excellent performance, the 100-m radio telescope in Effelsberg played an important role in the observations.

In August 2017, two neutron stars were observed colliding, producing gravitational waves that were detected by the American LIGO and European Virgo detectors....

Im Focus: Light from a roll – hybrid OLED creates innovative and functional luminous surfaces

Up to now, OLEDs have been used exclusively as a novel lighting technology for use in luminaires and lamps. However, flexible organic technology can offer much more: as an active lighting surface, it can be combined with a wide variety of materials, not just to modify but to revolutionize the functionality and design of countless existing products. To exemplify this, the Fraunhofer FEP together with the company EMDE development of light GmbH will be presenting hybrid flexible OLEDs integrated into textile designs within the EU-funded project PI-SCALE for the first time at LOPEC (March 19-21, 2019 in Munich, Germany) as examples of some of the many possible applications.

The Fraunhofer FEP, a provider of research and development services in the field of organic electronics, has long been involved in the development of...

Im Focus: Regensburg physicists watch electron transfer in a single molecule

For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.

The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...

Im Focus: University of Konstanz gains new insights into the recent development of the human immune system

Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens

Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...

Im Focus: Transformation through Light

Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light

When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Global Legal Hackathon at HAW Hamburg

11.02.2019 | Event News

The world of quantum chemistry meets in Heidelberg

30.01.2019 | Event News

Our digital society in 2040

16.01.2019 | Event News

 
Latest News

How the intestinal fungus Candida albicans shapes our immune system

22.02.2019 | Life Sciences

Correct antibiotic dosing could preserve lung microbial diversity in cystic fibrosis

22.02.2019 | Health and Medicine

The evolution of grain yield – Decoding the genetic basis of floret fertility in wheat

22.02.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>