Materials of the future – Graphene and metals

Trace amounts of graphene and other layered materials are often sufficient to enhance the properties of other materials. Graphene Flagship researchers add graphene to metals, plastics and other materials, to make them much stronger, lighter, conductive and so forth. Whether embedded, layered or sprayed, graphene introduces new properties to existing products or allows the development of new ones. It also reduces the amount of materials required to achieve the same performance, or to raise performance to previously unattainable levels.  

In this “Materials of the future” series, we look at several examples of how researchers around the world have used graphene with other materials, while being environmentally conscious. We begin this series “Materials of the future” with graphene and metals.  

Tackling future copper shortage  

Graphene boasts some unique properties that cannot be found in other non-metallic materials. It is considered a semi-metal, because it shares some properties with semi-conducting metals. Free electrons in the graphene structure enable the efficient conduction of electricity, while the lack of electrons (holes) lead to high thermal conductivity.  

As the globe becomes increasingly electrified, the demand for metals, particularly copper, will grow by an order of magnitude over the next several decades. On the flip side, a shortage of 10 million tonnes of copper is projected already by 2030.  

Graphene Flagship Associated Member GraphMaTech (Sweden) aims to reduce the need of copper, replacing part of it with graphene. Compared with copper alone, copper-graphene composites perform better in several properties, including hardness, Young’s modulus and tensile strength at room temperature. Furthermore, graphene fillers maintain the copper’s mechanical properties and reduce electromigration effects, which can cause circuits’ loss of connections or failure.  

“We have developed technologies to integrate graphene within metals, with the ambition to improve metal-graphene composites. We can boost the property of metallic materials, which means that a smaller amount of metals is needed in certain applications. We are focusing on electrification applications and we also looking at using graphene-metals that are hydrogen-compatible for the hydrogen economy of the future,” said Mamoun Taher, CEO at Graphene Flagship partner Graphmatech AB during the “Enabling the green transition with graphene technology” webinar organised by Graphene Flagship Work Package for Innovation.  

From rare elements to carbon 

Beyond copper, graphene can also replace rare and precious metals, leading to a more sustainable and resource-efficient fabrication. Scarce metals, such as tin, silver, tungsten and indium, are rare as well as difficult to extract. Yet they are key components in our electronic devices. For example, indium is widely used, mostly in the form of indium tin oxide, in a wide range of devices from touch screens to LED lights. At the same time, it is listed on the EU’s list of critical raw materials – materials that are important economically but have a high supply risk.  

Several research groups are focusing on this issue. In 2017, researchers at Graphene Flagship Partner Chalmers University of Technology (Sweden) studied the main applications of 14 different metals and explored how they could be replaced with carbon nanomaterials, including graphene. For example, graphene could coat touchscreens and other displays, taking the place of indium tin oxide.  

Graphene in space applications 

Researchers from Graphene Flagship partner institutes Université libre de Bruxelles (Belgium), University of Cambridge (UK), CNR Bologna (Italy), and Leonardo (Italy) have tested the thermal and physical properties of a graphene-based foam used in loop heat pipe – heat transfer devices that cool electronic devices in satellites and spacecraft. The cooling effect is achieved by evaporating a fluid inside a wick, typically made of porous metal. By coating the wick with a graphene-based foam, the researchers aim to improve the heat transfer as graphene enhances evaporation. This foam also improves the capillary pressure of the wick, allowing the working fluid to travel more quickly through the loop heat pipe. In 2017, the test took place in a parabolic flight, operated by the European Space Agency (ESA) and Novespace (France). 

References  

Arvidsson, Rickard, and Björn A. Sandén. "Carbon nanomaterials as potential substitutes for scarce metals." Journal of Cleaner Production 156 (2017): 253-261. 

Weng, Zhichao, et al. "Wafer‐Scale Graphene Anodes Replace Indium Tin Oxide in Organic Light‐Emitting Diodes." Advanced Optical Materials 10.3 (2022): 2101675.