Used cigarette butts may power future computers

Scientists have successfully converted used cigarette butts into a high performing material that could be integrated into computers, handheld devices, electric vehicles and wind turbines to store energy.

This new way to store energy also offers a solution to a growing environmental problem, researchers said.

The material outperforms commercially available carbon, graphene and carbon nanotubes.

It may someday be used to coat the electrodes of supercapacitors: electrochemical components that can store extremely large amounts of electrical energy.

"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 for meeting the energy demands of society," said co-author Professor Jongheop Yi of Seoul National University.

"Numerous countries are developing strict regulations to avoid the trillions of toxic and non-biodegradable used cigarette filters that are disposed of into the environment each year. Our method is just one way of achieving this," said Yi.

Carbon is the most common material found in supercapacitors due to its low cost, high surface area, high electrical conductivity and long term stability.

Scientists around the world are working to improve the characteristics of supercapacitors - such as their energy density, power density and cycle stability - while trying to reduce production costs.

In their study, Yi and colleagues demonstrated that the cellulose acetate fibres found in most cigarette filters could be transformed into a carbon-based material using a simple, one-step burning technique called pyrolysis.

The resulting material contained a number of tiny pores, increasing its performance as a supercapacitive material.

"A high performing supercapacitor material should have a large surface area, which can be achieved by incorporating a large number of small pores into the material," said Yi.

"A combination of different pore sizes ensures that the material has high power densities, which is an essential property in a supercapacitor," said Yi.

Once fabricated, the carbon-based material was attached to an electrode and tested in a three-electrode system to see how well the material could adsorb electrolyte ions (charge) and then release them (discharge).

The material stored more electrical energy than commercially available carbon, graphene and carbon nanotubes.

The research was published in the journal Nanotechnology.