Is Hemp Better than Graphene?
Marijuana has recently been touted as a "miracle plant," potentially treating a host of nearly untreatable medical conditions in various ways. Surprisingly, there have even been studies and real-world examples of this success. However, now researchers are suggesting the plant can be used for more than just medicine, claiming that hemp-based fibers might just usher in the next age of electronics.
David Mitlin led a team of researchers in the hopes of making the next economic supercapacitor - an energy storage device with the huge potential to change how the next generation of electronics are powered.
Unlike traditional batteries, modern supercapacitors can charge and discharge within seconds. Unfortunately, what has been holding them back is a combination of material cost and physicial restrictions. The standard supercapacitor today lacks energy density - an important quality that determines how much energy it can hold.
Stronger than a diamond, exceptionally conductive and flexible like rubber, graphene was hailed as the next futuristic material that would boost supercapacitor potential, raising their energy density while maintaining their fantastic output and charge times.
However, graphene always had its flaws. For one, as a now state-of-the-art material, it is initially expensive to make. For another, its immense surface area makes it difficult to keep flawless.
"Our device's electrochemical performance is on par with or better than graphene-based devices," Mitlin said during his presentation. "The key advantage is that our electrodes are made from bio-waste using a simple process, and therefore, are much cheaper than graphene."
And the "bio-waste" he's talking about is hemp.
"People ask me: why hemp? I say, why not?" Mitlin told BBC News. "The hemp we use is perfectly legal to grow. It has no THC [tetrahydrocannabinol] in it at all - so there's no overlap with any recreational activities."
According to a study published in the ACS's NANO, Mitlin and his team found that if they heated hemp fibers for 24 hours at about 350 degrees Fahrenheit, and then briefly blasted this "cooked" material with even more intense heat, it would exfoliate into something that resembles carbon nanosheets. Adding an ionic liquid into the material seals the deal, making a highly conductive material with a massive amount of surface area, just like graphene.
"Obviously hemp can't do all the things graphene can," Mitlin conceded to BBC, "but for energy storage, it works just as well."