Conductivity in Ionic Liquids: Decoupling of ions diffusion from structural relaxation

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Ionic liquids present a relatively new class of materials important for great variety of applications, from batteries and fuel cells, to "green" solvents and bio-technologies. Unique properties of these liquids (e.g. ionic conduction, extremely low vapor pressure) give them significant potential for use in future sustainable energy applications and environmentally friendly chemistry. Due to large variety of possible constituent ions, this class of materials potentially represents millions of chemically different liquids. This diversity opens tremendous opportunity for fine tuning of the ionic liquids properties for any desired applications. However, rational design of these materials requires fundamental understanding of the relationship between their chemical structure and macroscopic properties. In particular, understanding parameters that control molecular motions, ionic conductivity and viscosity is crucial for many applications of ionic liquids. This award supports Prof. Alexei Sokolov of the University of Tennessee, Knoxville and his research group to study the microscopic mechanisms controlling ionic conductivity and dynamics in ionic liquids. The research plan utilizes a combination of dielectric spectroscopy, light and neutron scattering studies and viscosity measurements. Using their expertise in dynamics of glass forming liquids and polymers, Prof. Sokolov and his research group expect to develop a comprehensive description of the mechanism of ionic conductivity in ionic liquids, its dependence on chemical structure, size of the ions and cation-anion interactions. They also expect the results of their work to deepen understanding of the dynamics of ionic liquids and to reveal the role of Coulombic interactions in structural relaxation of this new class of materials.Room temperature ionic liquids present new class of materials with significant potential for use in current and future sustainable energy and green chemistry applications. Understanding ionic motions and structural relaxation in these materials is crucial for rational design and synthesis of new materials with properties desired for particular applications. This project focuses on fundamental understanding of the molecular level mechanisms controlling the macroscopic properties of ionic liquids. The results may lead to developments of more efficient electrolytes for batteries, supercapacitors and other electrical energy storage applications. Education of specialists for future technologies is a significant part of the proposed program. Graduate and undergraduate students are actively involved in this research. Outreach activities to recruit future scientists from underrepresented groups and K-12 students are also planned. This project also promotes active collaboration with national multi-user facilities at the Oak Ridge National Laboratory.