Scientists throughout the world are exploring the use of liquid salts in a
variety of electrochemical devices that could some day lead to more robust lithium
ion batteries, fuel cells, organic cells and other novel applications.
Rochester Institute of Technology
scientist Tom Smith is experimenting with synthesizing liquid salts into a gel.
He recently received an EAGER (EArly-concept Grants for Exploratory Research)
grant from the National Science Foundation to create an entirely new material—a
polymer, or a plastic, from ionic liquid monomers—that will confine charge-carrying
ions in a gelled, pseudo-liquid state.
Smith will bypass the loss of conductivity that results from tethering free-moving
ions by incorporating the gelatinous ionic-liquid polymer into composite materials
at nanoscopic dimensions.
"There are some reports indicating that if you reduce the dimensionality
of a system of ions, the conductivity goes up," says Smith, professor of
chemistry and microsystems at RIT, who was recently selected as a member of
the American Chemical Society's inaugural class of fellows. "We're talking
200 angstroms or 20 nanometers small—about 4,000 times smaller than the
diameter of a human hair. How these polymer chains are distributed in the composite
and how the ions associated with them move can be different."
Smith is trying to tap the amazing conductivity of room temperature ionic liquids—a
unique class of salts that exist in a liquid state over a wide temperature range,
extending from room temperature to well below zero, and exhibit high ionic conductivity,
nonvolatility, and nonflammability.
"I see them being useful in capacitors for energy storage, and for better
organic solar cells," he adds. "Right now solar cells are made of
silicon. They're relatively expensive. I see the possibility that these materials
might be of use in those areas. We're going to explore that possibility."
Once contained in nanostructured, film-forming polymers, room temperature ionic
liquids will enable scientists to do certain things that cannot be done with
any other material, Smith says.
"Room temperature ionic liquids that are stable in the air were first
created in 1992, so they're fairly new," Smith says. "If you're dealing
with liquids, you have to contain them. We'd like to have the properties of
an ionic liquid in a state that's not liquid."
Nanomaterials derived from ionic liquid polymers have not been synthesized
prior to Smith's current experimental study.
"The material we're working on is very hard to make, mostly because it
will polymerize spontaneously before you want it to," Smith says. "And
to synthesize a dissymmetric ion, necessary in the formation of salts that are
liquid at room temperature, requires chemical reactions that have several steps—and
steps that are not necessarily easy to carry out."
Students contributing to Smith's study include graduate researcher Darren Smith
and, during the past summer, Darius Wynn, an undergraduate student studying
electrical engineering in RIT's College of Applied Science and Technology. High
school student Jaquest Wilson-MacDonald, from Wilson Magnet High School in the
Rochester Central School District, also worked on the project this summer. Wynn
was supported by the NSF's Louis Stokes Alliances for Minority Participation
Program. Wilson-MacDonald participated as part of the ACS' Project SEED Summer
Research Internship Program for Economically Disadvantaged High School Students.
"In addition to the potential to impact technological applications where
one might want to use an ionic liquid, the research is a great vehicle for teaching
concepts to our students and having them think in revolutionary ways,"
Smith says.
Smith expects to add three more graduate students to his synthetic chemistry
laboratory during the next two years.
Posted September 16th, 2009
