Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Could hemp nanosheets topple graphene for making the ideal supercapacitor?

Abstract:
Title

Interconnected carbon nanosheets derived from hemp for ultrafast supercapacitors with high energy

Abstract

We created unique interconnected partially graphitic carbon nanosheets (10-30 nm in thickness) with high specific surface area (up to 2287 m2 g-1), significant volume fraction of mesoporosity (up to 58%), and good electrical conductivity (211-226 S/m) from hemp bast fiber. The nanosheets are ideally suited for low (down to 0°C) through high (100°C) temperature ionic liquid-based supercapacitor applications: At 0°C and a current density of 10 A g-1, the electrode maintains a remarkable capacitance of 106 F g-1. At 20,60, and 100 oC and an extreme current density of 100 A g-1, there is excellent capacitance retention (72-92%) with the specific capacitances being 113, 144 and 142 F g-1, respectively. These characteristics favorably place the materials on a Ragone Chart providing among the best power - energy characteristics (on an active mass normalized basis) ever reported for an electrochemical capacitor: At a very high power density of 20 kW kg-1 and 20, 60 and 100 °C, the energy densities are 19, 34 and 40 Wh kg-1, respectively. Moreover the assembled supercapacitor device yields a maximum energy density of 12 Wh kg-1, which is higher than commercially available supercapacitors. By taking advantage of the complex multi-layered structure of a hemp bast fiber precursor, such exquisite carbons were able to be achieved by simple hydrothermal carbonization combined with activation. This novel precursor-synthesis route presents a great potential for facile large-scale production of high-performance carbons for a variety of diverse applications including energy storage.

Could hemp nanosheets topple graphene for making the ideal supercapacitor?

San Francisco, CA | Posted on August 12th, 2014

As hemp makes a comeback in the U.S. after a decades-long ban on its cultivation, scientists are reporting that fibers from the plant can pack as much energy and power as graphene, long-touted as the model material for supercapacitors. They're presenting their research, which a Canadian start-up company is working on scaling up, at the 248th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society.

The meeting features nearly 12,000 presentations on a wide range of science topics and is being held here through Thursday.

David Mitlin, Ph.D., explains that supercapacitors are energy storage devices that have huge potential to transform the way future electronics are powered. Unlike today's rechargeable batteries, which sip up energy over several hours, supercapacitors can charge and discharge within seconds. But they normally can't store nearly as much energy as batteries, an important property known as energy density. One approach researchers are taking to boost supercapacitors' energy density is to design better electrodes. Mitlin's team has figured out how to make them from certain hemp fibers — and they can hold as much energy as the current top contender: graphene.

"Our device's electrochemical performance is on par with or better than graphene-based devices," Mitlin says. "The key advantage is that our electrodes are made from biowaste using a simple process, and therefore, are much cheaper than graphene."

The race toward the ideal supercapacitor has largely focused on graphene — a strong, light material made of atom-thick layers of carbon, which when stacked, can be made into electrodes. Scientists are investigating how they can take advantage of graphene's unique properties to build better solar cells, water filtration systems, touch-screen technology, as well as batteries and supercapacitors. The problem is it's expensive.

Mitlin's group decided to see if they could make graphene-like carbons from hemp bast fibers. The fibers come from the inner bark of the plant and often are discarded from Canada's fast-growing industries that use hemp for clothing, construction materials and other products. The U.S. could soon become another supplier of bast. It now allows limited cultivation of hemp, which unlike its close cousin, does not induce highs.

Scientists had long suspected there was more value to the hemp bast — it was just a matter of finding the right way to process the material.

"We've pretty much figured out the secret sauce of it," says Mitlin, who's now with Clarkson University in New York. "The trick is to really understand the structure of a starter material and to tune how it's processed to give you what would rightfully be called amazing properties."

His team found that if they heated the fibers for 24 hours at a little over 350 degrees Fahrenheit, and then blasted the resulting material with more intense heat, it would exfoliate into carbon nanosheets.

Mitlin's team built their supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte. Fully assembled, the devices performed far better than commercial supercapacitors in both energy density and the range of temperatures over which they can work. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.

"We're past the proof-of-principle stage for the fully functional supercapacitor," he says. "Now we're gearing up for small-scale manufacturing."

###

Mitlin, who conducted the research while at the University of Alberta, acknowledges funding from Alberta Innovates Technology Futures, National Institute for Nanotechnology (Canada) and Alberta Livestock and Meat Agency.

A press conference on this topic will be held Tuesday, August 12, at 10:30 a.m. Pacific time in the Moscone Center, North Building. Reporters may report to Room 113 in person, or access live video of the event and ask questions at the ACS Ustream channel www.ustream.tv/channel/acslive.

####

About American Chemical Society
The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 161,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

For more information, please click here

Contacts:
Michael Bernstein
415-978-3506 (S.F. Press Center, Aug. 9-13)
202-872-6042


Katie Cottingham, Ph.D.
415-978-3506 (S.F. Press Center, Aug. 9-13)
301-775-8455

Copyright © American Chemical Society

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

'Memtransistor' brings world closer to brain-like computing: Combined memristor and transistor can process information and store memory with one device February 22nd, 2018

Graphene/ Graphite

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

A new radiation detector made from graphene: A new bolometer exploits the thermoelectric properties of graphene February 6th, 2018

Engineers develop flexible, water-repellent graphene circuits for washable electronics January 24th, 2018

Chemistry

Ultra-efficient removal of carbon monoxide using gold nanoparticles on a molecular support: New method and mechanism for state-of-the-art gas purification February 9th, 2018

Fast-spinning spheres show nanoscale systems' secrets: Rice University lab demonstrates energetic properties of colloids in spinning magnetic field February 7th, 2018

Discoveries

Basque researchers turn light upside down February 23rd, 2018

Histology in 3-D: New staining method enables Nano-CT imaging of tissue samples February 22nd, 2018

Developing reliable quantum computers February 22nd, 2018

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

Materials/Metamaterials

Basque researchers turn light upside down February 23rd, 2018

Atomic structure of ultrasound material not what anyone expected February 21st, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Announcements

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Histology in 3-D: New staining method enables Nano-CT imaging of tissue samples February 22nd, 2018

Developing reliable quantum computers February 22nd, 2018

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Histology in 3-D: New staining method enables Nano-CT imaging of tissue samples February 22nd, 2018

Developing reliable quantum computers February 22nd, 2018

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Leti Chief Scientist Barbara De Salvo Will Help Kick Off ISSCC 2018 with Opening-Day Keynote: In Addition, Leti Scientists Will Present and Demo New Technology for Piezoelectric Energy Harvesting February 8th, 2018

Round-the-clock power from smart bowties February 5th, 2018

NTU scientists create customizable, fabric-like power source for wearable electronics January 30th, 2018

Ultra-thin memory storage device paves way for more powerful computing January 17th, 2018

Events/Classes

European & Korean Project To Demo World’s First 5G Platform During Winter Games February 15th, 2018

Leti’s Chief Scientist Presents Optimistic Vision for Neuromorphic Hardware and Ultra-Low-Power Microdevices for Edge Computing at ISSCC: Leti’s Chief Scientist Presents Optimistic Vision for Neuromorphic Hardware and Ultra-Low-Power Microdevices That Are Based on Novel Emerging February 13th, 2018

Leti Chief Scientist Barbara De Salvo Will Help Kick Off ISSCC 2018 with Opening-Day Keynote: In Addition, Leti Scientists Will Present and Demo New Technology for Piezoelectric Energy Harvesting February 8th, 2018

Leti Presents Optical-Equipment Curving Technology that Improves Performance, Cuts Costs: ‘Disruptive Approach’ for Imaging Applications Presented in Paper At Photonics West and Demonstrated in Leti’s Booth February 2nd, 2018

Alliances/Trade associations/Partnerships/Distributorships

New era in high field superconducting magnets – opening new frontiers in science, nanotechnology and materials discovery January 9th, 2018

Leti Field Trials Demonstrate New Multicarrier Waveform for Rural, Maritime Broadband Radio: Field Trial in Orkney Islands Used New Filtered Multicarrier Waveform at 700MHz Band with Flexible Bandwidth Usage (Fragmented and Continuous Spectrum) December 18th, 2017

A new product to help combat mouldy walls, thanks to technology developed at the ICN2 December 14th, 2017

JPK Instruments announce partnership with Swiss company, Cytosurge AG. The partnership makes Cytosurge’s FluidFM® technology available on the JPK NanoWizard® AFM platform December 8th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project