Graphene as a material for energy generation and storage is a continuing source of inspiration for scientists, businesses, and technology writers. Back in May we wrote a review article on graphene batteries and supercapacitors, however, while you were resting on a sandy beach, graphene was busy learning how to increase the efficiency and reduce the cost of our energy systems.
Multilayer graphene device. Image courtesy of: University of Manchester
Supercapacitors are batteries that can recharge and discharge almost instantly, meaning that a laptop or cellphone could charge within a few seconds, instead of the hour or two that we're used to now. Couple that with high energy density, and you get an electric car that charges at an "electric station" within a few minutes. Graphene supercapacitors have existed in research labs for over two years, but the problem was to find a suitable method of mass production.
In February this year, UCLA researchers created some heat when they showed that graphene supercapacitors could be printed onto a DVD. Now, engineers in Australia have shown a new type of graphene supercapacitor that packs as much energy density as a standard car battery. Not only that, but the engineered process is similar to traditional paper-making, which makes the whole thing scalable and economical. We are especially happy that the chemical reaction starts from graphene oxide, one of our staple products. It's only two chemical steps from the oxide until the material is ready for plugging into a battery.
While it's true that supercapacitors may radically change our daily lives, the various processes have yet to be tested on a large scale and the entire mass production chain needs to be optimized, which will take some time - we're just not used to supercapacitors. Meanwhile, graphene-based electrodes for regular batteries have made tremendous progress over the summer, with potential impact on solar energy.
MIT has been a graphene research hub since the beginning and continues to show excellence in graphene innovation. A series of recent publications from the group led by Silvija Gradečak showcases a new class of advanced solar cells, composed of multiple layers of nanostructured materials. In some of the cells, graphene features as a transparent electrode. The novelty of Silvija's most recent research is that active components of a solar cell have been grown on graphene without degrading graphene's inherent quality and ability to guide current efficiently. The research is a step forward towards flexible printable solar cells.
The MIT team is not the only one thinking how to integrate graphene into electrodes. Swedish scientists have figured out that the addition of maghemite, or iron oxide similar to the red ore found in nature, to a layer of graphene, causes the graphene to roll up in a nanoscroll. The nanoscrolls turn out to have very good properties for application as electrodes in lithium-ion batteries. Curiously, the chemical process is almost 100% efficient, meaning that all graphene sheets in a solution curl up into nanoscrolls.
Perhaps most stunning of all recent graphene-for-energy research is that from Michigan Technological University which shows that graphene can replace costly platinum in solar cell electrodes, without a reduction in efficiency. The research involves a novel variety of graphene, which looks like a 3D honeycomb. The process is neither expensive nor difficult, and the research team is convinced the 3D honeycomb will be making it to a solar cell near you shortly.
Graphene Energy Catches Attention of Journalists
Graphene has been in the spotlight lately more than usual, with various journal articles summarizing recent scientific progress and the current market. Writers are fascinated with graphene's potential to revolutionize green energy, and the material's use for renewable energy in general. Interestingly, last week's report in the Wall Street Journal quotes an industry professional that "within half a year, graphene will be used for touchscreens in commercially available cellphones". We are looking forward to the dynamic months ahead and will keep you posted on developments related to this wonderful material.