Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

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

SEMATECH to Showcase Innovation and Advances in Manufacturing at SEMICON Japan 2014: SEMATECH experts will share the latest techniques, emerging trends and best practices in advanced manufacturing strategies and methodologies November 26th, 2014

Australian startup creates world’s first 100% cotton hydrophobic T-Shirts November 26th, 2014

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Chemistry

Lawrence Livermore researchers develop efficient method to produce nanoporous metals November 25th, 2014

Aromatic food chemistry to the making of copper nanowires November 24th, 2014

UO-industry collaboration points to improved nanomaterials: University of Oregon microscope puts spotlight on the surface structure of quantum dots for designing new solar devices November 20th, 2014

Graphene

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Researchers engineer improvements of technology used in digital memory November 24th, 2014

Discoveries

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Vegetable oil ingredient key to destroying gastric disease bacteria: In mice, therapeutic nanoparticles dampen H. pylori bacteria and inflammation that lead to ulcers and gastric cancer November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Materials/Metamaterials

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Lawrence Livermore researchers develop efficient method to produce nanoporous metals November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Aromatic food chemistry to the making of copper nanowires November 24th, 2014

Announcements

SEMATECH to Showcase Innovation and Advances in Manufacturing at SEMICON Japan 2014: SEMATECH experts will share the latest techniques, emerging trends and best practices in advanced manufacturing strategies and methodologies November 26th, 2014

Australian startup creates world’s first 100% cotton hydrophobic T-Shirts November 26th, 2014

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

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

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Vegetable oil ingredient key to destroying gastric disease bacteria: In mice, therapeutic nanoparticles dampen H. pylori bacteria and inflammation that lead to ulcers and gastric cancer November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

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

OCSiAl Builds Worldwide Partnership Network November 12th, 2014

Drexel Engineers Improve Strength, Flexibility of Atom-Thick Films November 11th, 2014

A billion holes can make a battery November 10th, 2014

Super stable garnet ceramics may be ideal for high-energy lithium batteries October 21st, 2014

Events/Classes

SEMATECH to Showcase Innovation and Advances in Manufacturing at SEMICON Japan 2014: SEMATECH experts will share the latest techniques, emerging trends and best practices in advanced manufacturing strategies and methodologies November 26th, 2014

Professional AFM Images with a Three Step Click SmartScan by Park Systems Revolutionizes Atomic Force Microscopy by Automatizing the Imaging Process November 24th, 2014

3rd Iran-Proposed Nano Standard Approved by International Standard Organization November 22nd, 2014

Sustainable Nanotechnologies Project November 20th, 2014

Alliances/Partnerships/Distributorships

SEMATECH to Showcase Innovation and Advances in Manufacturing at SEMICON Japan 2014: SEMATECH experts will share the latest techniques, emerging trends and best practices in advanced manufacturing strategies and methodologies November 26th, 2014

New research project supports internationalisation in nano-research: Launch of new “Baltic Sea Network” November 22nd, 2014

UO-industry collaboration points to improved nanomaterials: University of Oregon microscope puts spotlight on the surface structure of quantum dots for designing new solar devices November 20th, 2014

A novel method for identifying the body’s ‘noisiest’ networks November 19th, 2014

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More












ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE