Scientists in Singapore have come up with a ‘fruity’ way of finding an environmentally-friendly method of recycling lithium-ion batteries.
A team led by Nanyang Technological University, Singapore (NTU Singapore), has developed a method of using orange peel and citric acid to recover reusable metals from spent lithium-ion batteries.
Researchers have made functional batteries from the recovered metals, which they claim showed a similar charge capacity to commercial batteries. Further research to optimise the charge-discharge cycling performance is underway.
The team found oven-dried orange peel ground into powder and citric acid could achieve the same results as using acids to leach reusable materials from black mass when utilising the hydrometallurgy methods of recycling.
In experiments, the team reported the method extracted around 90% of cobalt, lithium, nickel, and manganese from spent lithium-ion batteries— comparable, they say, to using hydrogen peroxide.
The findings were published in the journal Environmental Science & Technology.
Dalton Tay, assistant professor of the NTU School of Materials Science and Engineering and School of Biological Sciences, said: “The key lies in the cellulose found in orange peel, which is converted into sugars under heat during the extraction process.
“These sugars enhance the recovery of metals from battery waste. Naturally-occurring antioxidants found in orange peel, such as flavonoids and phenolic acids, could have contributed to this enhancement as well.
“In Singapore, a resource-scarce country, this process of urban mining to extract valuable metals from all kinds of discarded electronics becomes very important. With this method, we not only tackle the problem of resource depletion by keeping these precious metals in use as much as possible, but also the problem of e-waste and food waste accumulation– both a growing global crisis.”
Professor Madhavi Srinivasan, co-director of the NTU Singapore-CEA Alliance for Research in Circular Economy (NTU SCARCE) laboratory, said the research had demonstrated it was possible to use biodegradable substances in the industrial recycling of lithium-ion batteries.
He said: “Processes of e-waste are energy-intensive and emit harmful pollutants and liquid waste, which point to an urgent need for eco-friendly methods as the amount of e-waste grows.
“This waste-to-resource approach could also potentially be extended to other types of cellulose-rich fruit and vegetable waste, as well as lithium-ion battery types such as lithium iron phosphate and lithium nickel manganese cobalt oxide. This would help to make great strides towards the new circular economy of e-waste, and power our lives in a greener and more sustainable manner.”
