University Develops Hemp-based Super Capacitors


Hemp Fiber Supercapacitor

Super-capacitors can store and release electricity like a battery, but can be recharged in seconds instead of hours. At the moment, they are usually made from graphene, a man-made super material that is 100 times stronger than steel by weight, conducts electricity better than copper, and is more flexible than rubber. Unfortunately, graphene is very costly to produce. A team of researchers led by David Mitlin at Clarkson University in New York have found a way to produce super-capacitors from an inexpensive hemp fiber left over from textile and building material construction that could pave the way for a mainstream super-capacitor.

Mitlin admits that his hemp fiber can’t do everything that graphene can, but for energy storage it works just as well – and at a tiny fraction of the price. The first step, he explains, “is to cook it – almost like a pressure cooker. It’s called hydrothermal synthesis. Once you dissolve the lignin and the semicellulose, it leaves these carbon nanosheets – a pseudo-graphene structure.” These sheets are then assembled into electrodes and an ionic liquid added as the electrolyte, resulting in super-capacitors which operate at a broad range of temperatures and a high energy density.

The American Chemical Society Journal ranks the hemp based material “on par with or better than commercial graphene-based devices”. It says the hemp fiber’s properties work down to 0 C and display some of the best power-energy combinations reported in the literature for any carbon. Fully assembled, their energy density is 12 Wh/kg, which can be achieved at a charge time of less than six seconds.

Why is this important?

We reported just yesterday that Tesla is working on a battery that uses graphene anodes to double the range of its cars. Elon Musk is quoted as saying the new technology could find its way into Tesla automobiles “soon”, if they make economic sense.

Substitute Mitlin’s new hemp based material for the graphene in  Musk’s experimental battery and you have a device with high energy storage ability and fast recharge times. Which means the lowly hemp plant, so long despised and vilified, may be the key to unlocking the the secret of affordable, practical electric cars.



Source | Images: Inhabitat

About the Author

I have been a car nut since the days when Rob Walker and Henry N. Manney, III graced the pages of Road & Track. Today, I use my trusty Miata for TSD rallies and occasional track days at Lime Rock and Watkins Glen. If it moves on wheels, I’m interested in it. Please follow me on Google + and Twitter.

  • Steve Grinwis

    I think the researches mostly just wanted a way to legally produce lots of hemp for testing.

  • Steve Hanley

    I know you have your tongue in your cheek when you say that, Steve. But we really need to get over the wink-wink/nudge-nudge reaction every time someone uses the word “hemp”.

    Opinions vary about whether it was the alcohol industry or the chemical companies that financed “Reefer Madness” and started the whole “hemp is a dangerous commodity” insanity. The truth is that hemp grows where other plants will not with very little water and almost no fertilizer. it is an excellent source of vegetable oil that is almost as multi-talented as petroleum. It can not only power our cars as bio-diesel fuel, it can also be the source for virtually all the plastics we now make from oil.

    In other words, hemp can do in an environmentally friendly way what fracking does. It may be one of the important keys to a renewable, petroleum free future.

    • Steve Grinwis

      It was just a joke. :p

  • gendotte

    The “Gotcha” here is what happens below freezing? 0 Celsius would leave pretty much everyone outside of the tropics without transportation for a significant part of the year.

  • UncleB

    Advances in American Science filled with these bogey men? Watch now as Asia, China surpass the U.S., driven on practical grounds for advancement. Politburo, ‘Group of Seven’ have made electric transportation a goal by decree in China. Tesla even held back in Texas? Change belongs to China and the 21st Century does too?

  • Keith D.

    This won’t replace the Model S battery anytime soon. At 12 Wh per Kg, you’re looking at nearly 16,000 lbs of capacitors to achieve the already existing 265 mile range of the 85 kWh Model S battery that only weighs something like 1,200 lbs.

  • Robert Endl

    Uh…Capacitor Madness?

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