When Adam and Eve were donning their iconic leaf in the Garden of Eden, back in those creation days, little did they know that a few generations down the line, their very outfit would be looked at as a possible energy storage device, or battery. As far fetched as it may sound, this ain’t the stuff of fairy tales…
Researchers at the University of Maryland Materials Science and Engineering department have been poking at leaves to explore alternative energy storage possibilities that don’t require the use of lithium, which is widely used in batteries found in consumer electronic devices. A 2013 report by the US Environmental Protection Agency analysing the life-cycle impact of lithium-ion batteries found that those containing nickel and cobalt showed the highest potential for harmful environmental impacts such as resource depletion, ecological toxicity and more.
Liangbing Hu, an assistant professor at the department, said “A leaf is designed by nature to store energy for later use, and using leaves in this way could make large-scale storage environmentally friendly.”
Having picked a leaf from the university grounds, and having heated it up 1,000 degrees Celsius first, in order to remove everything except its underlying carbon structure they explain, the team then tapped into the natural porosity of the leaf and pumped it with sodium electrolytes, which carry the charge, therefore turning it into a battery negative terminal, or anode.
Although other studies have investigated the use of banana peel, melon skin and peat moss as electrical energy storage properties, a leaf is altogether fitter for this purpose, thanks to its natural shape and intricately-packed internal structure.
Apart from powering countless electronic devices, lithium and lithium-ion batteries are also used to power electric and hybrid cars and smart grids, highlighting a key reason why a move towards more sustainable energy storage options is necessary.
The findings were published in the journal ACS Applied Materials and Interfaces, and now form the basis for further research to find leaves with the best thickness, flexibility and structure for electrical energy storage.
Want to know some battery basics? This TED lecture comes to the rescue: