Researchers have developed a method that turns durian into super-capacitors that can charge phones, laptops, and more.
Behold the durian. A fruit so storied for its stink that it is banned in some public transportation systems and brings shudders of repulsion to many. Sure, the flesh of the fetid fruit has its charms – it's creamy and sweet with a funky edge. But the smell is something else; think mango with equal parts rubber, garlic, honey, gym socks, and various rotten things.
If you have any experience with durian, you know what we're talking about. But here's something we haven't given much thought to: What happens to all that madly malodorous durian waste? And could it be put to good use somewhere?A new study from the University of Sydney reveals the answer:
"Durian waste, as a zero-cost substance that the community wants to get rid of urgently due to its repulsive, nauseous smell, is a sustainable source that can transform the waste into a product to substantially reduce the cost of energy storage through our chemical-free, green synthesis protocol," says Associate Professor Vincent Gomes.
Looking for new ways to develop energy storage devices with high energy density to meet the challenges of global warming and rapidly depleting fossil fuel, the team took on durian and jackfruit to try and create electrochemical super-capacitors.
"Super-capacitors are like energy reservoirs that dole out energy smoothly," explains Gomes. "They can quickly store large amounts of energy within a small battery-sized device and then supply energy to charge electronic devices, such as mobile phones, tablets and laptops, within a few seconds."
"Using durian and jackfruit purchased from a market, we converted the fruits' waste portions (biomass) into super-capacitors that can be used to store electricity efficiently," he adds.
"Using a non-toxic and non-hazardous green engineering method that used heating in water and freeze drying of the fruit's biomass, the durian and jackfruit were transformed into stable carbon aerogels -- an extremely light and porous synthetic material used for a range of applications."
"Carbon aerogels make great super-capacitors because they are highly porous. We then used the fruit-derived aerogels to make electrodes which we tested for their energy storage properties, which we found to be exceptional," Gomes says. "Compared to batteries, super-capacitors are not only able to charge devices very quickly but also in orders of magnitude greater charging cycles than conventional devices.
The team found that the super-capacitors they prepared were significantly more efficient than current ones, which are made from activated carbon.
"Durian waste was selected based on the excellent template nature provides for making porous aerogels," Gomes says. "The durian and jack-fruit super-capacitors perform much better than the materials currently in use and are comparable, if not better, than the expensive and exotic graphene-based materials."
Gomes says that naturally-derived super-capacitors are leading the way for developing high efficiency energy storage devices, a necessary step in the face of climate change and dwindling supplies of fossil fuels.
"We have reached a point where we must urgently discover and produce ways to create and store energy using sustainably-sourced materials that do not contribute to global warming," he adds. And if those ways happen to find a use for piles of putrid produce waste that packs an electrical punch, then all the better.
The study, "Aerogel from fruit biowaste produces ultracapacitors with high energy density and stability," was published in Journal of Energy Storage.