Fragments of plastic that pollute water sources across the world and are聽thought to be harmful to our health could be recycled to make electrodes for lithium-ion batteries.
at Inha University in South Korea and his colleagues have found a way to extract microplastics made of polyethylene 鈥� the most common type of plastic 鈥� from contaminated water and turn them into electrodes for lithium-ion batteries. This is the type of battery commonly used to power phones, laptops and electric vehicles.
To do this, the researchers placed two pieces of iron foil into roughly 200 millilitres of water containing 0.5 grams of polyethylene microplastics 鈥� a relatively high concentration. The fluid also contained a comparable amount of salt as seawater.
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By connecting the iron foil to an electrical circuit, Choi and his colleagues generated positively charged iron particles in the solution. These bound to the negatively charged microplastics, which are less than 5 millimetres across.
They used a magnet to extract the now iron-coated microplastics and heated them to create iron nanoparticles coated with a layer of carbon derived from the microplastics.
The researchers combined the coated nanoparticles with powdered graphite and created 14-millimetre-wide discs that could each act as one of the electrodes 鈥� the anode 鈥� in a battery.
The lithium-ion batteries containing the microplastic-derived discs could store roughly five times as much electric charge per gram as ones with anodes made of graphite alone.
However, graphite ones 鈥� which are commonly used in lithium-ion batteries 鈥� can keep their capacity for more than 1000 recharges, whereas this declined in the microplastic-derived electrodes after about 600 charges, says at Northumbria University, UK.
鈥淩emoving microplastics from wastewater to generate material for batteries I think is a beautiful idea for moving towards a circular economy,鈥� says Rasul. The approach should also work with different types of microplastics, but this needs to be tested, he says.
However, it is unclear how easy it would be to scale up the approach.
鈥淚t has potential for dealing with wastewater from specific facilities, for example that coming from pharmaceutical factories,鈥� says Rasul. But it probably wouldn鈥檛 work on a larger scale, such as in oceans, because that would require huge magnets, says Rasul.
Ultimately, the sheer amount of microplastics polluting our water sources means many approaches are needed, he says.
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