Tag Archives: hemp batteries

Earth Power: Hemp Batteries Better Than Lithium And Graphene

 Henry Ford’s Model T was famously made partly from hemp bioplastic and powered by hemp biofuel. Now, with battery-powered vehicles starting to replace those that use combustion engines, it has been found that hemp batteries perform eight times better than lithium-ion. Is there anything that this criminally-underused plant can’t do?

The comparison has only been proven on a very small scale. (You weren’t expecting a Silicon Valley conglomerate to do something genuinely groundbreaking were you? They mainly just commercialise stuff that’s been invented or at least funded by the state.) But the results are extremely promising.

The experiment was conducted by Robert Murray Smith – who has built up quite a following on his YouTube channel – of FWG Ltd in Kent. He observed a Volts by Amps curve of both the hemp and lithium batteries and found that the power underneath the hemp cell was a value of 31 while that of the lithium cell had a value of just 4. Although he does not claim to have proven anything, he said that the results of his experiment showed that the performance of the hemp cell is “significantly better” than the lithium cell.

It comes as no real surprise, which is presumably why he conducted the experiment. In 2014, scientists in the US found that waste fibres – ‘shiv’ – from hemp crops can be transformed into “ultrafast” supercapacitors that are “better than graphene”. Graphene is a synthetic carbon material lighter than foil yet bulletproof, but it is prohibitively expensive to make. The hemp version isn’t just better, it costs one-thousandth of the price.

The scientists “cooked” leftover bast fibre – the inner bark of the plant that usually ends up in landfill – into carbon nanosheets in a process called hydrothermal synthesis. “People ask me: why hemp? I say, why not?” said Dr David Mitlin of Clarkson University, New York, in an interview with the BBC. “We’re making graphene-like materials for a thousandth of the price – and we’re doing it with waste.”

Dr Mitlin’s team recycled the fibres into supercapacitors, energy storage devices which are transforming the way electronics are powered. While conventional batteries store large reservoirs of energy and drip-feed it slowly, supercapacitors can rapidly discharge their entire load.

This makes them ideal in machines that require sharp bursts of power. In electric cars, for example, supercapacitors are used for regenerative braking. Releasing this torrent requires electrodes with high surface area, one of graphene’s many phenomenal properties.

Mitlin says that “you can do really interesting things with bio-waste”. With banana peels, for example, “you can turn them into a dense block of carbon – we call it pseudo-graphite – and that’s great for sodium-ion batteries. But if you look at hemp fibre its structure is the opposite – it makes sheets with high surface area – and that’s very conducive to supercapacitors.”

Once the bark has been cooked, “you dissolve the lignin and the semicellulose, and it leaves these carbon nanosheets – a pseudo-graphene structure”. By fabricating these sheets into electrodes and adding an ionic liquid as the electrolyte, his team made supercapacitors which operate at a broad range of temperatures and a high energy density.

Mitlin’s peer-reviewed journal paper ranks the device “on par with or better than commercial graphene-based devices”.

“They work down to 0C and display some of the best power-energy combinations reported in the literature for any carbon,” he adds. “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.” Fully assembled, their energy density is 12 Wh/kg – which can be achieved at a charge time less than six seconds.

At the end of 2018, Texas-based electric motorcycle company Alternet announced that it was working with Mitlin to power motorbikes for its ReVolt Electric Motorbikes subsidiary.

So there you have it. If we already knew that there is no need to use the fossil fuels that are destroying the planet’s climate, because hemp biofuel provides a better alternative, we now know that there is no need to destroy the environment by mining for lithium and the materials that are used in batteries. We can literally grow technology. Hemp can save and power the world.

This article was first published in The Quarter Leaf issue 1.

Hemp Batteries Could Become A Reality

Researchers have found a way to boost the energy density of supercapacitors through the use of more sophisticated electrodes. These electrodes are composed of hemp fibers, and they have a high energy storage capacity.

The development breakthrough has been made by a Canadian start-up company, led by Dr. David Mitlin. The idea arose from some applied thinking, when Mitlin’s group decided to see if they could make graphene-like carbons from hemp bast fibers.

From Mitlin’s research, it seems that hemp fibers can hold as much energy and power as graphene, the current favored material for 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.

Mitlin’s group discovered that when hemp fibers were heated for 24 hours at a little over 350 degrees Fahrenheit this would exfoliated the material into carbon nanosheets. From the reformed material, the group constructed supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte. In tests, the devices performed far better than commercial supercapacitors. This was assessed by examining for energy density and across a range of temperatures. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, which is two to three times higher than currently available commercial systems.

Interviewed by Phys.Org, Mitlin expands on the success so far: “Our device’s electrochemical performance is on par with or better than graphene-based devices. The key advantage is that our electrodes are made from biowaste using a simple process, and therefore, are much cheaper than graphene.”

The parallels with graphene are a reference to the considerable research that has gone into to new variant of carbon. Graphene is a single-layer mesh of carbon atoms. Graphene is considered the new “wonder material,” due its durability and lightness. Graphene can be described as a one-atom thick layer of graphite.

Mitlin’s new research could trigger the electronic industry to move in a new direction. The research group are currently preparing the hemp-based prototype supercapacitor for small-scale manufacturing.

– Article originally posted on DigitalJournal.com