Along with a staggering waste of human lives, the pandemic has produced a waste crisis of a different sort: all the masks, gloves, and other single-use personal protective equipment thrown away. One team offer a potential solution, having found a way to recycle surgical masks into something that tackles an even bigger problem: climate change.
Professor Anvar Zakhidov of Russia's National University of Science and Technology and researchers at three Mexican institutions disinfected waste surgical masks and dipped them in graphene ink. Heat processing then converted the masks into electrodes, while mask material processed in a different way was used as separating material to produce supercapacitors.
They describe the manufacturing process and performance indicators in the Journal of Energy Storage.
Supercapacitors operate differently from traditional batteries, but they do the same job, storing electricity for when it is needed. Zakhidov proposes household uses such as clocks or lamps, but ultimately if the idea is scaled up it could help give solar and wind the backup to displace fossil fuels.
Crucially, “the material is pressed...and heated to 140°C (conventional supercapacitor batteries require very high temperatures for pyrolysis-carbonation, up to 1,000-1,300°C [1,800-2,400°F], while the new technology reduces energy consumption by a factor of 10),” Zakhidov said in a statement.
With an almost endless supply of the raw materials and little energy requirements in the processing, the product has the potential to be very cheap. Moreover, Zakhidov and co-authors claim their product has a density of energy storage almost ten times that of competing technology, putting it in the range of commercial viability. The team then managed to more than double their previous energy density record to 208 watt hours per kilogram by adding Ca3Co4O9-δ oxide nanoparticles. That's denser than typical electric car batteries, although the comparison is imperfect since car batteries require additional packaging.
Speaking of packaging, Zakhidov's team encased their product in protective shells made from discarded blister packs such as are used to store medications.
Like other supercapacitors, their product can release its energy quickly, giving it advantages over many energy storage technologies.
The fact the best performance for the batteries required cobalt could be an obstacle to mass production, since battery manufacturers are desperately seeking replacements for the scarce metal, whose production is plagued by human rights abuses. Nevertheless, the cobalt-free version is dense enough for some purposes, even if no substitute can be found.
The idea of turning face masks into energy storage devices might seem rather random, but many porous materials have been tested for this purpose, including waste car tires and coconut shells. Although these frequently work, they usually require high temperature processing.
Zakhidov has not reported whether N95s are as superior for energy storage, compared to traditional masks, as they are for keeping out viruses.