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As hemp cultivation returns in the US after being banned for many years, researchers believe that the amount of power and energy that can be packed into the fibers from this plant is comparable to that of graphene, which has long been considered as the ideal material for supercapacitors.
A study into this phenomenon was presented at the American Chemical Society's (ACS) 248th National Meeting & Exposition.
David Mitlin, Ph.D., from Clarkson University in New York, stated that when compared to present-day rechargeable batteries, which accumulate energy over a number of hours, supercapacitors are capable of charging and discharging energy within a matter of seconds.
Therefore, these energy storage devices have great potential to revolutionize the way next-generation electronics are powered. These supercapacitors have a low energy density, or in other words, cannot store the amount of energy that can be stored in batteries.
In order to increase the energy density of supercapacitors, Mitlin's team developed unique electrodes from specific hemp fibers, capable of holding as much energy as the wonder material, graphene.
Mitlin's team also explored to see whether graphene-like carbons could be made from hemp bast fibers. These fibers, obtained from the plant’s inner bark, are often discarded by industries that utilize hemp for a wide range of products such as construction materials, clothing and other products.
The team discovered that if the fibers were heated for 24h at a temperature over 350°F (177°C) and then subjected to blasting with increased heat intensity, carbon nanosheets are formed. The supercapacitors developed by Mitlin’s team comprised hemp-based carbons and an ionic liquid as the electrode and electrolyte, respectively.
Once the devices were assembled, their performance was much better than commercial supercapacitors in terms of energy density and temperature range over which they work. The energy density produced by these hemp-based devices was as high as 12 Watt-hours/kilogram, which was significantly higher than that of commercial devices.
This wasn't the only interesting piece presented at the ACS 248th National Meeting & Exposition. A white paper which discusses the issue of dwindling supplies of elements that are used in smartphones was also presented, highlighting the drastic need for reducing the consumption of certain precious elements currently being used in high quantities.
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