Researchers at Chalmers University of Technology, Sweden, have developed a graphene assembled film that has over 60% higher thermal conductivity than graphite film, despite graphite consisting of many layers of graphene.
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 3,500 and 5,000W/mK. If you put two graphene layers together, then it theoretically becomes graphite, as graphene is only one layer of graphite.
What has the research changed?
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 1,950W/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. They discovered that the thermal conductivity of graphene assembled film can reach up to 3,200W/mK, which is over 60% higher than the best graphite films.
The researchers have done this through careful control of both grain size and the stacking orders of graphene layers.
According to the university, the high thermal conductivity is a result of large grain sizes, high flatness, and weak interlayered binding energy of the graphene layers. With these important features, phonons can move faster in the graphene layers rather than interact between the layers, leading to higher thermal conductivity.
Professor Johan Liu, who is leading the research team, said: “This is indeed a great scientific breakthrough, and it can have a large impact on the transformation of the existing graphite film manufacturing industry.”
He continued: “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.”