Turn waste into treasure! The old mask has been successfully transformed into a battery with an energy density comparable to that of a lithium-ion battery.

In the current epidemic world, the significance of masks to people is self-evident, but at the same time, a large number of discarded old masks have a significant impact on the environment. Recently, scientists have shown a new way to deal with old masks, using them to make low-cost, flexible and efficient batteries.

In this "war against the epidemic", personal protective equipment ((PPE)) is one of our most important means of defense, but unfortunately, it must be disposable to provide maximum protection. This certainly adds to the huge burden of waste, with a 2020 study estimating that as many as 129 billion masks were used each month in the early stages of the epidemic. The waste is eventually buried in landfills, oceans and other environments, or burned, releasing toxic gases.

To ease the pressure, scientists are looking for ways to recycle masks into useful things, such as road materials. In this regard, a new study has found that after proper handling, waste masks are actually quite good batteries. The study was recently published in the Journal of Energy Storage.

First, researchers at (NUST) at Pakistan's National University of Science and Technology used ultrasound to disinfect the mask and then dipped the mask into graphene ink. Next, the mask is compressed and heated to 140 °C (284 °F) to form a conductive "ball" that acts as the electrode of the battery. They are separated by an insulating layer also made of an old mask, and then the whole thing is soaked in the electrolyte, finally covered with a protective shell made of another kind of medical waste (drug blister).

Of course, cleaning the mask is only part of the goal, and it won't help if the batteries produced are of poor quality, but they actually work unexpectedly. The team claims to have achieved an energy density of 99.7 watt-hours per kilogram (Wh/kg). This is close to the energy density of ubiquitous lithium-ion batteries, which range from 100 to 265Wh/kg.

It is reported that the researchers further improved the efficiency of the battery by adding nanoparticles of calcium and cobalt oxide peroxides to the electrode. This more than doubles the energy density, making it an amazing 208Wh/kg. The best-performing battery version retains 82% capacity after 1500 cycles and can provide more than 10 hours of energy at a voltage of up to 0.54 V.

The team says these batteries have other benefits. The use of waste products means that they are low-cost, and they can be made thin, flexible and even disposable when needed, although sexual use may weaken their original intentions to some extent.