Interconnected Carbon Nanosheets Derived from Hemp for Ultrafast Supercapacitors with High Energy

This is where I'm headed with the MOhemp Energy inventions: Hemp Batteries, Supercapacitors, Hemp Lignin, Energy Storage, etc

Abstract copied from: http://pubs.acs.org/doi/ipdf/10.1021/nn400731g

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–1) 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 °C 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 that of commercially available supercapacitors. By taking advantage of the complex multilayered 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.

Keywords: 

biomass; carbon nanosheets; ionic liquid; supercapacitor;energy storage

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Huanlei Wang†‡, Zhanwei Xu†‡, Alireza Kohandehghan†‡, Zhi Li†‡*, Kai Cui‡,Xuehai Tan†‡, Tyler James Stephenson†‡, Cecil K. King’ondu†‡, Chris M. B. Holt†‡, Brian C. Olsen†‡, Jin Kwon Tak§, Don Harfield§, Anthony O. Anyia§, andDavid Mitlin†‡*

† Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2 V4, Canada

‡ National Institute for Nanotechnology (NINT), National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada

§ Bioresource Technologies, Alberta Innovates-Technology Futures, Vegreville, Alberta, T9C 1T4, Canada

ACS Nano, 2013, 7 (6), pp 5131–5141

DOI: 10.1021/nn400731g

Publication Date (Web): May 7, 2013

Copyright © 2013 American Chemical Society

*Address correspondence to lizhicn@gmail.com, dmitlin@ualberta.ca.