Patrice Simon &
Yury Gogotsi talk with ScienceWatch.com and answer
a few questions about this month's Fast Breaking Paper in
the field of Materials Science. The authors have also
sent along images of their work.
Article Title: Materials for electrochemical
capacitors
Authors: Simon,
P;Gogotsi, Y
Journal: NAT MATER, Volume: 7, Issue: 11, Page: 845-854,
Year: NOV 2008
* Univ Toulouse 3, CIRIMAT, CNRS, UMR 5085, F-31062
Toulouse 4, France.
* Univ Toulouse 3, CIRIMAT, CNRS, UMR 5085, F-31062
Toulouse 4, France.
* Inst Univ France, F-75005 Paris, France.
* Drexel Univ, Dept Mat Sci & Engn, Philadelphia, PA
19104 USA.
Top: Patrice Simon, bottom: Yury
Gogotsi
Why do you think your paper is highly cited? Does
it describe a new discovery, methodology, or synthesis of
knowledge?
This paper describes the current state-of-the-art in the field of
electrochemical capacitors (ECs) or "supercapacitors," from both the
scientific and applications points of view. Many new discoveries have been
made and new applications have appeared since publication of the last major
review article dedicated to supercapacitors in 2001 (R. Kötz, et
al.). Those recent developments have brought ECs to the front edge of
the energy storage area. Thus, a review of the latest discoveries within
the entire field was timely and quite important for facilitating further
advances. It represents a synthesis of knowledge which provides an overall
summary while outlining future research directions.
Would you summarize the significance of your paper
in layman's terms?
ECs are high-power energy storage devices which can complement or even
replace batteries in those applications where fast-charge delivery or
uptake is needed for several seconds. Thanks to these unique properties,
the use of ECs has dramatically increased in the past three years in areas
ranging from backup power to cars, aircrafts, cranes, trams, electric
tools, etc.
View/download all accompanying slides
& descriptions of
figures. PDF
Today, the transition from gasoline to hybrid and electric engines in the
automotive industry offers tremendous opportunities to ECs in the recovery
of braking energy or in boosting the acceleration of cars powered by small
engines or batteries. This paper also presents the latest scientific
discoveries in the EC area, describing the future challenges and new
strategies developed to improve the energy and power densities of these
systems.
How did you become involved in this research, and
were there any problems along the way?
This paper resulted from cooperation between our two research groups at
Drexel University (Philadelphia, PA, USA) and Paul Sabatier University
(Toulouse, France). Professor Yury Gogotsi, a material scientist from
Drexel University and an expert in nanostructured carbon materials,
designed porous carbon with a narrow and tunable pore size distribution in
the sub-nanometer range. Together with Professor Patrice Simon, who is an
expert in capacitive energy storage, these two research groups achieved a
scientific breakthrough by showing that, in defying conventional wisdom,
carbon pores smaller than the size of the solvated ions of the electrolyte
(< 1 nm) were accessible to ions, opening new opportunities for the
design of a new generation of high-energy density supercapacitors. This
work was published in Science magazine in 2006 (J. Chmiola, et
al.) and ultimately led to the Nature Materials paper, which
presented a broader picture of the mechanisms of capacitive energy storage
and described new materials that enable the development of electrochemical
capacitors with an improved power and energy density.
Where do you see your research leading in the
future?
Our research is focused on understanding the mechanism of ion adsorption in
pores smaller than the solvated ion size. We will try to understand the ion
transport in nanopores, as well as to elucidate the increase of the charge
stored in the pores of the carbon electrodes when the pore size closely
matches the ion size. This research will have potential application not
only in the energy storage area (supercapacitors) but more generally in any
field dealing with ion transport through porous membranes such as water
desalination or the function of ion channels in cells.
We also will develop new materials for electrochemical energy storage with
the goal being to significantly increase the power and energy stored per
unit of weight and volume and to make supercapacitors as common as
batteries in energy storage applications.
Do you foresee any social or political
implications for your research?
There are many good economical reasons to switch to renewable resources
such as the sun, wind, ocean waves, geothermal, hydropower, etc. Another
reason for switching to renewables—even if you don't believe in
global warming—is the environment.
We breathe pollution coming from cars, buses, and coal-burning power
plants. Thus, few people doubt nowadays that renewable resources and
nuclear power generation will largely replace fossil fuels within the next
decade or two.
However, the energy produced from renewable resources is primarily
electrical energy. Therefore, solving the problem of electrical energy
storage is the critical issue in the transition to a renewable energy
economy. It will be impossible to become independent of gasoline, coal, and
natural gas if we don't develop much better and more efficient solutions
for the storage of electrical energy.
Supercapacitors are projected to be as important as batteries in moving
from "chemical" to "physical" energy, because they have a higher power and
lower losses (less energy is wasted in each storage cycle) compared to all
other electrical energy storage systems. Therefore, our research helps to
make this planet cleaner and healthier and our countries less dependent on
supplies of foreign oil.
Patrice Simon, Ph.D. Professor of Material Science Université Paul Sabatier CIRIMAT Laboratory (UMR CNRS 5085) Toulouse, France Web
Yury Gogotsi, Ph.D. Trustee Chair Professor of Materials Science and
Engineering Drexel University Philadelphia, PA, USA Web
KEYWORDS: DOUBLE-LAYER CAPACITORS; CARBIDE-DERIVED CARBON;
ACTIVATED CARBONS; NANOPOROUS CARBON; PORE-SIZE; ION SIZE; SUPERCAPACITOR
ELECTRODES; MESOPOROUS CARBONS; LITHIUM BATTERIES; ENERGY
MANAGEMENT.