Around the world, as many as 5.6 trillion cigarette butts are thrown into the environment every year -- that’s 766,571 metric tons of waste. Now researchers are putting that waste to good use: They've converted cigarette butts into a material they hope to use as a coating for the electrodes of supercapacitors -- electrochemical components for storing huge amounts of energy. 

If successfully integrated, the material could help power machines ranging from phones and computers to EVs and wind turbines. The work was published in Nanotechnology this week. 

Supercapacitors store energy via electrical charges rather than chemical reactions, the way batteries do, Gizmodo explains, which means they can charge and discharge much faster. But they’re huge, which prevents them from being used in small gadgets. Scientists are always looking for ways to make better supercapacitors, and they like to work with carbon because of its low cost, high electrical conductivity, and long-term stability. 

“Our study has shown that used cigarette filters can be transformed into a high-performing carbon-based material using a simple one-step process, which simultaneously offers a green solution to meeting the energy demands of society,” Jongheop Yi from Seoul National University says in a news release. 

Cigarette filters are made of synthetic cellulose acetate fibers. After collecting filters from Marlboro Light Gold, Bohem Cigar Mojito, and the One Orange cigarettes, Yi and colleagues transformed the toxic and non-biodegradable fibers into a carbon-based material using a one-step burning technique called pyrolysis. Burning the fibers in the presence of nitrogen results in a carbon-based material filled with tiny pores. These pores make it a better supercapacitive material by increasing the surface area. A combination of different pore sizes further ensures that the material can have high energy densities.

The team attached the carbon-based material to an electrode and tested it in a three-electrode system to see how well the material could adsorb electrons (charge) and then release them (discharge). The material, they found, stored a higher amount of electrical energy than commercially available carbon, graphene, and carbon nanotubes. 

Image: Ken Hawkins via Flickr CC BY 2.0