Supercapacitors are superior to batteries because they can load up on energy and discharge it much faster. They store electrical charges, unlike batteries, which store energy in chemicals. Unfortunately their size makes them impractical for most non-industrial applications.
Now a South Korean research team have found a way to shrink the size of supercapacitors, replacing carbon nanotubes and graphene with an unlikely (and inexpensive) substitute: burnt cigarette butts.
Conventionally, the devices rely on carbon because it is inexpensive, has a high surface area, has strong electrical conductivity and is stable. Now the team from Seoul National University says it has found a way to transform the cellulose acetate fibers in cigarette filters into a carbon-based material in a single, simple step. The filters are burned using a technique called pyrolysis. The resulting material contains many pores of different sizes, thus increasing its surface area and thus its performance. This is important in creating a high-performing supercapacitor, according to Professor Jongheop Yi, a co-author of the study.
“A combination of different pore sizes ensures that the material has high power densities, which is an essential property in a supercapacitor for the fast charging and discharging,” Yi says.
The scientists attach this substance to one electrode in a three-electrode supercapacitor to learn how well it could absorb and release a charge. They found that their material stored more energy than conventional carbon, graphene and even carbon nanotubes. That means that their form factor can shrink.