Financial Associated Press (Shanghai, editor Huang Junzhi) news, in the current epidemic-ravaged world, the significance of masks for 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 demonstrated a new way to deal with old masks, using them to make low-cost, flexible and efficient batteries.
Personal protective equipment (PPE) is one of our most important means of defense in this "war against the epidemic", but unfortunately, it must be disposable to provide maximum protection. This, of course, adds a 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 outbreak. This waste ends up being buried in landfills, oceans and other environments, or is incinerated, releasing toxic gases.
To alleviate this stress, scientists are looking for ways to recycle masks into something useful, such as road materials. In this regard, a new study has found that, with the right treatment, used masks are actually quite easy to use batteries. The results of this research have recently been published in the Journal of Energy Storage.
First, researchers at the National University of Science and Technology of Pakistan (NUST) sterilized the masks with ultrasound and then immersed them in ink made of graphene. Next, the mask is compressed and heated to 140 °C (284 °F) to form a conductive "pellet" that acts as an electrode for the battery. They are separated by an insulating layer also made of old masks, then the whole thing is soaked in electrolyte, and finally covered with a protective shell made of another medical waste (drug blister).
Of course, cleaning up the mask is only part of the purpose, and if the batteries produced are not of good quality, it will not help much, but these batteries are actually unexpectedly effective. The team claims that they achieved an energy density of 99.7 Wh/kg per kilogram. 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 battery efficiency by adding nanoparticles of calcium cobalt oxide peroxide to the electrodes. This more than doubled the energy density, bringing it to a surprising 208Wh/kg. The best-performing battery version retains 82% of its capacity after 1500 cycles and can provide more than 10 hours of energy at voltages up to 0.54V.
The team says there are a few other benefits to these batteries. Using scrap products means they cost a lot, and they can be thin, flexible, and even disposable when needed, although single-use may weaken their original intent to some extent.