Mask recommendations have evolved with the Covid-19 virus, and the latest Omicron variant is now driving up demand for surgical and N95 masks. These disposable masks save lives, but they are made of plastic microfibers and are exacerbating the world’s plastic-pollution problem. A recent report estimated that 1.56 million facemasks entered the oceans in 2020.
A team of researchers from Mexico and the U.S. have now found a way to turn disposable mask waste into batteries that can store as much energy as lithium-ion batteries, and could also be low-cost and flexible to boot. Their study appears in the Journal of Energy Storage.
The uptick in plastic waste resulting from the Covid-19 pandemic has triggered alarms globally. Last July, the United Nations estimated that “around 75 per cent of the used masks, as well as other pandemic-related waste, will end up in landfills, or floating in the seas.”
Scientists have been trying to come up with creative ways to address the issue. Last year, researchers in Australia showed that shredded single-use masks could be repurposed to make strong road materials.
In the new study, Jorge Oliva of the San Luis Potosí Institute of Scientific Research and Technology and colleagues made batteries from facemask waste and discarded plastic blister packs used to package medicine tablets.
The researchers started by disinfecting the masks using ultrasound, and dipping them into ink made of the carbon material graphene, which is known to be an excellent current conductor. They compressed and heated up the graphene-coated masks to make pellets, which they used to make the two electrodes of the battery. To improve the charge-holding capacity of the electrodes, they coated them with a special calcium-cobalt oxide material.
Electrodes in a battery need to be separated by an insulating material, and the researchers made this insulating layer with masks as well. Finally, they soaked this assembly in an electrolyte and wrapped the device in a protective case made from the waste blister packs.
The resulting battery had a energy density—which impacts how long a battery can power a device—of 208 Watt-hours per kilogram. That’s comparable with today’s commercial lithium-ion batteries, which have energy densities ranging from 100 to 265 Wh/kg. The devices continue to work when pressed, and could be made thin and flexible. Plus, the use of recycled waste should keep their costs low. Not bad for a battery made from medical waste.
Source: R. Mendoza et al. Highly efficient textile supercapacitors made with face masks waste and thermoelectric Ca3Co4O9-δ oxide. Journal of Energy Storage, 2022.
Image: ©Anthropocene Magazine
