Graphene, a carbon-based material with the atoms arranged in a honeycomb-like lattice, is believed to have potential in a whole range of applications from composite materials to light emitting diodes to touch panels and high frequency electronics. With its high electrical conductivity and large surface area per unit mass, it is an interesting material for energy storage, e.g. in advanced batteries and supercapacitors. [Engerati-Graphene Demonstrates Benefits For Storage (And Other Technologies)] The prospect of rapidly chargeable lightweight batteries could have a huge impact on energy storage on all scales from utility down to residential as well as other applications such as electric vehicles and portable electronics.
Recognizing the significant potential of graphene, The Graphene Flagship research initiative was established by the European Union in October 2013. With a budget of €1 billion, the initiative involving 142 partners in 23 countries and growing, is tasked with taking graphene from the laboratories into European society within ten years.
As part of this effort the Graphene Flagship has developed a roadmap outlining the key targets and research areas for graphene, related two-dimensional crystals and hybrid systems based on a combination of different 2D crystals and other nanomaterials. The roadmap, which is published in the Royal Society of Chemistry journal Nanoscale, covers the next 10 years and beyond, and its objective is to guide the research community and industry toward the development of products based on graphene and related materials.
The roadmap highlights three broad areas of activity. The first task is to identify new layered materials, assess their potential, and develop reliable, reproducible and safe large scale production. Identification of new device concepts enabled by 2D materials is also called for, along with the development of component technologies. The ultimate goal is to integrate components and structures based on 2D materials into systems capable of providing new functionalities and application areas.
Graphene for energy storage and conversion
The roadmap identifies at least applications for graphene and related materials for study over the next 10 years which should improve the performance and viability of batteries and electrochemical capacitor storage as well as fuel cells. These will be preceded at a science and technology level with a focus on production. Target developments for the next 3 years include the processing of graphene and related materials for PV wet technologies, the development of functionalized, decorated, curved or intercalated graphene-based materials, and the development of graphene-based composites including metal and nano-crystals.
At a component level development targets in years 3 to 7 are:
• PV electrodes and absorbers
• Fuel cell electrodes
• High capacitance graphene-based or mesoporous electrodes
• Battery lithium hosting electrodes
• Hydrogen hosting electrodes.
Applications these should enable include large roll-to-roll (R2R) PV cells, new absorbers based on natural dyes, very low platinum graphene-based electrodes, upscaled supercapacitors and batteries, and novel lithium dioxide (LiO2) battery concepts with an order of magnitude higher energy density supply than conventional Li batteries.
System level development can then follow with targets for years 7 to 10 including:
• Fully R2R PV cells integrating graphene and hybrid composites – giving rise to light, flexible and highly sustainable “biomimic” PV cells
• Low platinum graphene-based electrodes integrated in fuel cells – giving rise to sustainable fuel cells
• High power and cyclability batteries and supercapacitors – giving ride to light electrical storage systems
• Energy saving hydrogen uptake/release – giving rise to light hydrogen storage systems.
Novel graphene applications
In their conclusions the roadmap’s more than 60 authors note that the field of graphene, related 2D crystals and hybrids is now rapidly evolving from pure science to technology. Different applications require graphene and related materials with diverse properties, from structurally perfect and high μ graphene for high tech electronics to defective materials for energy storage applications.
The authors also comment that the target is to develop novel applications, planned thanks to the unique properties of each graphene or related material, rather than try to replace other materials in existing applications. Graphenes and related materials will replace existing standard materials only if the properties of the new components are amply competitive to justify the cost for changing current industrial processes.