Swedish researchers Graphene Flagship have developed a rechargeable battery made from graphene that they say could greatly improve the eco-friendly credentials of current e-bikes with lithium-ion batteries.
As graphene is non-toxic, Graphene Flagship say it's already a better choice than a metal-ion battery; and the results of their latest study in partnership with Trinity College Dublin in Ireland has shown that their creation has impressive credentials when it comes to the battery's life cycle too.
The researchers used 'metal-air' alternatives for their device, such as sodium-air (Na-O2) batteries, which are equipped with sodium anodes and oxygen-trapping cathodes. The Na-O2 gets produced when the battery is out of stored energy, which then gets recycled back to form metallic sodium and oxygen when the battery gets charged again.
A cathode (where the electrons flow through) was made using a porous graphene-based aerogel, which the Graphene Flagship team fabricated by electrochemically exfoliating graphite foils with the help of molecules derived from DNA building blocks, such as adenosine monophosphate. These 'biomolecules' insert into the graphite structure, causing the foils to swell. The foils are then scraped off and processed further, resulting in the formation of graphene flakes, around 1-2 nm in thickness and 400-600 nm in width.
The researchers found that the biomolecules are also absorbed on the surface of graphene, allowing the flakes to be dispersed in water and resulting in conductive ink. This ink has a very low impact on the environment, and using a freeze-drying technique the researchers transformed it into an aerogel that was suitable for the battery's cathode. These new batteries could be recharged 50 times with an efficiency of 94%, which Graphene Flagship say out-performs all other existing graphene-based cathodes.
Co-author of the study Nagore Ortiz-Vitoriano said: "We believe that the phosphates in these biomolecules are the main reason for this success. These chemical groups allow NaO2 to be recycled more quickly during the charging phase."
Andrea C. Ferrari, Graphene Flagship's Science and Technology Officer, comments: "Meeting the sustainable development goals is at the core of the Graphene Flagship science and innovation. Energy applications are amongst the promising impact areas for graphene and related materials. This works shows a sustainable approach for the production of graphene to be used in re-chargeable batteries, with a double advantage for the environment."
It's not the only exciting battery technology that could revolutionise the e-bike either; back in October we reported that Bosch are investing a cool 1 billion euros into silicon carbide microchips that can conduct electricity better, which they say will lead to better range, smaller batteries and less energy lost through heat.
Do you think even more sustainable production would sway more people to take the plunge and go electric? Let us know in the comments as always!