The shadow of the COVID-19 pandemic has made carrying surgical masks a part of daily life but consuming one mask a day also generates an astonishing amount of garbage. Now Russian scientists are investing in the "recycling" of discarded masks and have developed low-cost and high-efficiency batteries with energy density approaching today's common lithium-ion batteries.
Surgical masks are one of the most powerful weapons used to fight bacteria and viruses. They can effectively reduce the chance of droplet infection between people. Unfortunately, when masks become dank due to breathing or sweat, their efficacy will be reduced. Most masks are disposable and huge environmental costs have been incurred during the COVID-19 pandemic. Research in 2020 pointed out that in the early stages of the pandemic, up to 129 billion masks were used every month and they ended up in incinerators, landfills, or randomly discarded in the wild.
In response to this situation, the Russian National University of Science and Technology (MISiS) intends to give new life to discarded masks and other discarded medical supplies. First, since masks are prophylactic medical equipment, it is necessary to ensure that they harbor no pathogens before reuse. After the team completely disinfected the masks with ultrasonic waves, the masks were soaked in graphene ink, and compressed and heated to 140°C to form conductive particles that can be used in battery electrodes.
The team pointed out that traditional supercapacitor batteries usually rely on ultra-high temperatures for thermal cracking and carbonation. The required temperature is as high as 1000~1300°C and energy consumption is ten times that of this new technology.
Many materials used in this new battery come from discarded medical supplies including separators made from discarded masks and protective casings made from pharmaceutical packaging. The team also pointed out that the results of the study were unexpectedly good, with the energy density of the new battery coming in at 99.7 watt-hours per kilogram (Wh/kg), which is very close to the 100~265 Wh/kg of lithium-ion batteries.
Subsequently, in order to improve energy density, calcium cobalt oxide inorganic perovskite nanoparticles were also added to the electrode, doubling energy density to 208 Wh/kg. This battery was able to maintain 82% capacity after 1,500 charge-discharge cycles and could also provide more than 10 hours of power at 0.54 V.
The team believes that the use of discarded masks can greatly reduce the cost of materials and can also make thin and flexible batteries. In the future, they hope to apply this technology to electric vehicles, solar energy, and other applications.
Although collecting discarded masks is still a problem, the Russian team has imagined destinations for masks that are not garbage cans. In the past, the Royal Melbourne Institute of Technology (RMIT University) in Australia has also discovered the benefits of discarded masks and found that they can be made into stronger road materials and effectively improve the ductility and flexibility of recycled concrete aggregate (RCA).
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