Posted: Aug 05, 2014 |
Used-cigarette butts offer energy storage solution
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(Nanowerk News) A group of scientists from South Korea have converted used-cigarette butts into a high-performing material that could be integrated into computers, handheld devices, electrical vehicles and wind turbines to store energy.
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Presenting their findings today, 5 August 2014, in IOP Publishing's journal Nanotechnology ("Preparation of energy storage material derived from a used cigarette filter for a supercapacitor electrode"), the researchers have demonstrated the material's superior performance compared to commercially available carbon, graphene and carbon nanotubes.
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It is hoped the material can be used to coat the electrodes of supercapacitors—electrochemical components that can store extremely large amounts of electrical energy—whilst also offering a solution to the growing environmental problem caused by used-cigarette filters.
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It is estimated that as many as 5.6 trillion used-cigarettes, or 766,571 metric tons, are deposited into the environment worldwide every year.
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Co-author of the study Professor Jongheop Yi, from Seoul National University, said: "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.
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"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."
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Carbon is the most popular material that supercapacitors are composed of, due to its low cost, high surface area, high electrical conductivity and long term stability.
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Scientists around the world are currently working towards improving the characteristics of supercapacitors—such as energy density, power density and cycle stability—whilst also trying to reduce production costs.
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In their study, the researchers demonstrated that the cellulose acetate fibres that cigarette filters are mostly composed of could be transformed into a carbon-based material using a simple, one-step burning technique called pyrolysis.
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As a result of this burning process, the resulting carbon-based material contained a number of tiny pores, increasing its performance as a supercapacitive material.
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"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," continued Professor Yi.
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"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."
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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 electrolyte ions (discharge).
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The material stored a higher amount of electrical energy than commercially available carbon and also had a higher amount of storage compared to graphene and carbon nanotubes, as reported in previous studies.
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