Researchers from Russia’s National University of Science and Technology MISiS have developed a method of making solid-state ultracapacitors from recycling medical face masks used during the COVID-19 andemic.
Along with colleagues from the US and Mexico, the researchers’ method could go someway to ensuring the billions of units of the medical product are kept from landfill.
The supercapacitor achieved 98Wh/kg and, when nanoparticles of inorganic perovskite of CaCo oxide were added, the energy capacity of the batteries increased to 208Wh/kg.
The best device made with CaCo presented a capacitance retention of 82% after 1,500 cycles and discharge times of at least 10h (at a maximum output voltage of 0.54 V).
The study was published in the Journal of Energy Storage.
Scientists have tried various porous natural materials and waste products to make electrodes for supercapacitors, including: coconut shells, rice husks, newspaper waste, car tyre waste.
However, the materials required high-temperature annealing (charring) in special furnaces.
To create the latest supercapacitor, the team first disinfected the masks with ultrasound, then dipped them in an ‘ink’ made of graphene, which saturates the mask.
The material was then pressed under pressure and heated to 140°C (conventional supercapacitor batteries require very high temperatures for pyrolysis-carbonation, up to 1000-1300°C).
A separator (also made of mask material) with insulating properties was then placed between the battery electrodes made of the new material. It is saturated with a special electrolyte, and then a protective shell is created from the material of medical blister packs (such as paracetamol)
They have achieved a high electrical capacity of 1706 farads per gram (This is significantly higher compared to the capacity of the best-carbonised electrodes without the addition of graphene (1000 farads per gram).
In the future, the scientific team plans to apply the new technology to produce batteries for electric cars, solar power stations and other applications.
An estimated 53 million face masks are put into landfill each day in the UK, with 130 billion masks used globally every month due to the COVID-19 pandemic.
