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Hemp nanosheets rival graphene for conductivity

By Tim Sandle     Aug 14, 2014 in Science
Scientists have reported that fibers from hemp can pack as much energy and power as graphene, which is known as the "wonder" model material for making supercapacitors.
Supercapacitors are energy storage devices that have huge potential to transform the way future electronics are powered. Unlike batteries, which store energy chemically in the material of their electrodes, a capacitor stores energy physically, on the electrodes’ surfaces.
To date, most research has been orientated towards the use of graphene as the most appropriate material for the capacitors. Graphene is a single-layer mesh of carbon atoms. Graphene is a material suited for electronic devices due to its ability to conduct electricity at super-fast speeds.
Aside from graphene a new alternative has emerged: hemp. According to the American Chemical Society, researchers worked out how to make supercapacitors from certain hemp fibers, and the prototypes can hold as much energy as graphene.
The research group, led by David Mitlin, Ph.D., managed to construct graphene-like carbons from hemp bast fibers. The fibers come from the inner bark of the plant and often are discarded from the process where hemp is used for clothing.
The researchers found that if they heated hemp fibers for 24 hours at a little over 350 degrees Fahrenheit, and then blasted the resulting material with more intense heat, this would exfoliate into carbon nanosheets.
From this the science group built the supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte. Once fully assembled, the devices performed far better than commercial supercapacitors in tests for both energy density and the range of temperatures over which they can work. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.
More about Hemp, Graphene, conducitvity, Electricity
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