Hemp is a valuable and incredibly versatile crop, which can be used for numerous industrial purposes. Yet, researchers now suggest that hemp batteries are even more powerful than lithium and graphene.
Robert Murray Smith conducted an experiment and discussed it on his YouTube channel.
He observed a Volts by Amps curve of both the hemp and lithium batteries. He found that the power underneath the hemp cell had a value of 31 while the one of the lithium cell had a value of just 4.
Smith explains that his experiment does not prove anything, but the results indicate that the performance of the hemp cell is “significantly better” than the lithium cell.
However, these findings are not new, as, in 2014, researchers in the US discovered that waste fibers — “shiv” — from hemp crops can be transformed into “ultrafast” supercapacitors that are “better than graphene.”
Graphene is a unique synthetic carbon material which is lighter than foil and bulletproof. The race toward the ideal supercapacitor has largely focused on it, as it is a strong material made of atom-thick layers of carbon, which can be made into electrodes when stacked.
Scientists are investigating how they can enjoy the benefits of graphene’s unique properties to build better solar cells, water filtration systems, touch-screen technology, as well as batteries and supercapacitors.
Yet, the main problem with its use is feasibility, while hemp costs one-thousandth of its price.
Researchers presented their work at the American Chemical Society meeting in San Francisco, and say that electric cars and power tools could harness this hemp technology.
Dr. David Mitlin of Clarkson University, New York, led the team, and in their experiment, they “cooked” leftover bast fibre — the inner bark of the plant that typically ends up in landfills — into carbon nanosheets. This process is called hydrothermal synthesis.
The team heated the fibers for 24 hours at a little over 350 degrees Fahrenheit, and then blasted the resulting material with more intense heat until it exfoliated into carbon nanosheets.
They built their supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte.
Conventional batteries store large reservoirs of energy and drip-feed, while supercapacitors rapidly discharge their entire load, and are perfect in machines that require sharp bursts of power.
For instance, electric cars, supercapacitors are used for regenerative braking.
Dr.Mitlin explained that they chose hemp as they can actually make graphene-like materials for a thousandth of the price- from waste!
What’s more, he added that the hemp they use is perfectly legal to grow, as it contains no THC, and there’s no overlap with any recreational activities.
Finding cheap, sustainable alternatives is the specialty of Dr. Mitlin’s former research group at the University of Alberta. The team has experimented with all kinds of biowaste -- from peat moss to eggs.
Dr.Mitlin says that bio-waste can be used in various interesting ways. Yet, the secret is to tailor the right plant fibre to the right electrical device -- according to their organic structure.
The structure of the fibre of hemp makes sheets with high surface area, which is very conducive to supercapacitors.
After the bark is cooked, the lignin and the semicellulose are dissolved, leaving carbon nanosheets – a pseudo-graphene structure.
The supercapacitors operate at a broad range of temperatures and a high energy density.
According to the peer-reviewed journal paper, the resulting device is “on par with or better than commercial graphene-based devices.”
Mitlin explained that supercapacitors work down to 0C and display some of the best power-energy combinations reported in the literature for any carbon.
“For example, at a very high power density of 20 kW/kg (kilowatt per kilo) and temperatures of 20, 60, and 100C, the energy densities are 19, 34, and 40 Wh/kg (watt-hours per kilo) respectively.”
If fully assembled, the energy density is 12 Wh/kg, which can be achieved at a charge time of less than six seconds.
“Obviously hemp can’t do all the things graphene can,” Dr. Mitlin concludes that hemp can’t do all the things graphene can, but in the case of energy storage, it works just as well while costing a fraction of the price -$500-1,000 a tonne.
Therefore, his start-up company Alta Supercaps is hoping to begin small-scale manufacturing. They intend to market devices to the oil and gas industries since the high-temperature operation is a valuable asset for them.
In 2018, the Texas-based electric motorcycle company Alternet reported that it intends to join forces with Mitlin to power motorbikes for its ReVolt Electric Motorbikes subsidiary.
Dr. Mitlin added that hemp is a waste product looking for a value-added application. Therefore, if the technology really takes off -- it could help economies.
Plus, it is a robust plant, and a lot of farmers would be thrilled to grow hemp.
As it is decriminalized, other companies can also follow suit and help transition our planet to run on sustainable energy.