Researchers are saying there are batteries intended to use for electric vehicles that are made out of fibers collected from plants, making the environmentally-friendly alternative to conventional combustion-based vehicles take another step forward.
Significantly, the researchers even claim that this plant-based battery even performs better compared to the conventional lithium-ion cells that are used in vehicles—both combustion and electric.
Notably, researchers are referring to use the often-discarded fibers from the hemp plant. Hemp or more popularly known as the Cannabis sativa plant is a strain of the same plant species that is grown specifically for the industrial uses of its derived products. It is one of the fastest-growing plants and was one of the first plants to be spun into usable fiber 10,000 years ago.
However, in current uses of the hemp plant, since it’s legalization in some countries, industries often discard the fibers that are its by-product.
Robert Murray Smith, on the other hand, discovered that it could be repurposed rather than simply getting disposed.
In an experiment, Smith found that a Volts by Amps curve of both the hemp and lithium batteries and that the power underneath the hemp cell was a value of 31 while that of the lithium cell had a value of just 4.
He first showed off the experiment in his YouTube channel, which garnered quite a following. Although he does not claim that he has 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.
Similarly, scientists also conducted the experiment on ’shiv’ or hemp’s waste fibers in 2014. They published their findings in The Quarter Leaf issue 1.
In the article, they detailed that the 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.
In an experiment, scientists “cooked” leftover fibers or the inner bark of the plant into carbon nanosheets in a process called hydrothermal synthesis, which produces these graphene-like 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, the team made supercapacitors which operate at a broad range of temperatures and from a high energy density.
In comparison to the expensive graphene, the hemp version isn’t just better, it costs one-thousandth of the price.
“People ask me: why hemp? I say, why not?” said David Mitlin of Clarkson University, New York, and an author of the study, told in an interview. “We’re making graphene-like materials for a thousandth of the price – and we’re doing it with waste.”
Notably, Miltin’s team argues that hemo-based batteries are better because unlike conventional batteries, they store large reservoirs of energy and drip-feed it slowly, supercapacitors can rapidly discharge their entire load.
Electric vehicles can benefit from this power because, in contrast to combustion vehicles, electric vehicles can pump power the moment you step on the gas. For instance, Tesla vehicles can reach 0 to 60 kmh in a matter of seconds because they don’t need to burn gas that produces similar power.
Furthermore, Miltin also advocates that plant-based energy can do more and be sourced from different plants.
”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 fiber its structure is the opposite – it makes sheets with a high surface area – and that’s very conducive to supercapacitors.”
“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.