In Indonesia it is customary to consume a tropical fruit called durian that smells deeply rotten. For some people it is the stinkiest food in the world. Such is its stench that even some hotels in Southeast Asia have it forbidden. Its appearance, moreover, is not very pleasant: it is of considerable size (up to 30 centimeters), it has an elongated or rounded shape and is covered by thorns. In fact, its name comes from the Malay “duri”, which means thorn.
However, this fruit would be able to charge the battery of a smartphone .
This is at least what Vincent G. Gomes , associate professor at the University of Sydney and co-author of a new study describing a novel method of using durian biological waste to make faster and more efficient electric chargers, the equivalent of to a powerbank. Their work was published in the Journal of Energy Storage in early 2020.
Durian’s secret lies in the structural precision of natural biomass, with its strategically scattered pores, offering an exceptional resource as a template for the synthesis of carbon-based materials.
More sustainable
In a climate change scenario where there is also a rapid decline in fossil fuels, the adoption of supercapacitors to store energy with which to feed, for example, devices or even vehicles, remains expensive, which is why Gomes has resorted to waste relatively inexpensive organic , such as durian.
Conventional batteries have two electrodes, separated by an electrolyte, which is just a chemical that serves as a catalyst to cause a chemical reaction within the battery. These reactions convert the chemicals inside a battery into new substances that release electrical energy . Once all the chemicals inside have been used up, the processes stop and the battery dies. Rechargeable batteries, by contrast, allow internal chemical reactions to run in both directions, becoming cyclical in nature. That is why the lithium-ion battery inside a smartphone , for example, can be charged and discharged over and over again.
If a battery stores electrical energy in the form of chemical energy, a capacitor stores electrical energy in a magnetic field. Although capacitors are much less efficient than batteries, the advantage is that they do not use toxic metals and can be recharged almost infinitely .
Supercapacitors , however, would be more efficient. In general, supercapacitors are built with two sheets of metal that are coated with a material such as activated carbon, which works as an electrode, creating a larger surface to store more charge. The main supercapacitors are those that are made as aerogels, carbon nanotubes or activated carbon.
Gomes and the rest of his team then lyophilized the biomass of two fruits, both durian ( Durio zibethinus ) and jackfruit ( Artocarpus heterophyllus ), which transformed an extremely light and porous synthetic material into stable carbon aerogels. Current supercapacitors are made of activated carbon which are not as efficient as those prepared during this study, and those made of aerogels are derived from expensive and exotic graphene-based materials.
This project is a further step in the development of more efficient supercapacitors. Perhaps the durian will end up being a more efficient and more sustainable substitute of the current plastic powerbanks .
Reference: Kenny Lee, Luba Shabnam, Shaikh Nayeem Faisal, Van Chinh Hoang, Vincent G. Gomes, “Aerogel from fruit biowaste produces ultracapacitors with high energy density and stability”, Journal of Energy Storage, Volume 27, 2020,101152, ISSN 2352 -152X, https://doi.org/10.1016/j.est.2019.101152.
