FY2010 - Oak Ridge National Laboratory

Director’s R&D Fund—
Ultrascale Computing and Data Science
05259
Computer Design and Predictive Simulation of High-Capacity,
Cyclable, and Versatile Nanoporous Supercapacitors
for Energy Storage Applications
Bobby G. Sumpter, Vincent Meunier, Robert J. Harrison, and William A. Shelton
Project Description
In this project, we proposed the development of multiscale computational tools to investigate and optimize
key variables of supercapacitors based on nano-porous carbon materials. With the projected doubling
of world energy consumption within the next decades, there is a desperate need for low-emission
sources of energy. However, the use of electricity generated from renewable sources requires efficient
electrical energy storage. A particularly promising technology is carbon supercapacitors, which have
higher power density than batteries and have higher energy density than conventional dielectric
capacitors due to the large surface area provided by the nanometer-sized pores. The capacitance of a
supercapacitor depends on complex phenomena occurring in the pores, the effective dielectric constant of
the electrolyte, and the thickness of the double layer formed at the interface. Experimental
measurements are hard to perform and difficult to interpret, especially at the nanoscale. Optimization of
these key variables requires a fundamental understanding that can only be obtained through detailed
scalable first-principles calculations combined with mesoscale and microscale simulation tools. As
part of this project, we will further improve the scaling of our first-principles methods along with the
heat (micro), mass (micro), and ionic (meso) transport codes. These types of simulations require
computational resources that can only be provided by the National Center for Computational
Sciences (NCCS). This work will uniquely position ORNL as the lead institution in simulation of
energy storage materials.
Mission Relevance
The research and development of this project will have immediate impact into the prime mission of
DOE. It fits exceptionally well into the new DOE Energy Frontier Research Centers and additionally
should be of considerable interest to the Office of Energy Efficiency and Renewable Energy
(EERE). On the computing side of DOE, developing scalable methods that are able to fully utilize
petascale systems can enable predictive simulations of entire device structures from first principles,
thereby helping to rationally design more efficient materials and functionalities. The fundamental
aspects of charge storage, motion, solvation, and de-solvation also have large ramifications to
biology because ion channels are quite important in nearly all types of life forms. As such we expect
considerable interest from the National Institutes of Health (NIH) and the Environmental Protection
Agency (EPA). Efficient energy storage is also of importance to the Global Nuclear Energy
Partnership (GNEP). In addition, the potential use of supercapacitors for portable power systems
crosscuts the continued and high-priority interest of the Department of Defense.
Results and Accomplishments
Our original project outlined three well-defined objectives. First, we wanted to understand the role of
pore size and shape on the processes relevant to adsorption and energy storage. Our work towards that
objective has been to provide a quantum mechanical–based model that accurately describes the behavior of
capacitive energy stored for the entire range of pore sizes ranging from subnanometer micropores,
mesopores, to macropores. Devising such a model was made possible by large-scale quantum
calculations performed on the NCCS computational resources (Jaguar and Eugene). Remarkably, our
model has already been accepted as the state-of-the-art description of carbon-based supercapacitors [see
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