Ion Solvation and Mobility in Ionic Liquids
ILs are considered nonflammable and they have negligible vapor pressures; thus are safer alternatives over organic solvents for lithium, lithium-ion and sodium-ion batteries where aqueous electrolytes are not suitable. To improve ion conduction in ILs, we must first understand ion solvation and mobility. We employ Raman spectroscopy to study solvate structures in complex IL-IL mixtures and electrochemical techniques to perform ion transference measurements. The outcome of this study is pertinent to high energy density, lithium based battery chemistry with implifications in other applications such as electrodeposition processes.
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The interfacial structure of ionic liquids (ILs) near electrified surfaces do not follow classical theories such as Helmholtz, Gouy-Chapman and Stern. We investigate these complex interfaces utilizing advanced spectroscopy and scattering techniques, coupled with electrochemical methods. In particular, the accessibility and wettability of ionic liquid ions in electrical double layer capacitors that utilize high surface area porous electrodes are of interest for high performance energy storage devices. We design and synthesize ILs to better develop the structure-property relations that govern the electrode-electrolyte interfaces.
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Deep Eutectic Solvents: Understanding Structure and Physical Properties
DES are alternatives to ILs and constitute a hydrogen bond donor and a hydrogen bond acceptor as opposed to discrete ions. Owing to their good solvent strength, achieving high concentrations of redox active species are possible. Therefore, DES are promising for redox flow batteries. Our focus is to understand the liquid structure and physical properties as a function of DES composition. We further characterize the redox activity of functionalized salts in DES.
This project is part of Breakthrough Electrolytes for Energy Storage (BEES): a DOE Energy Frontier Research Center.
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Polymer-ionic liquid Composite Capsules and Membranes for Gas Separations
ILs have high CO2 solubilities and can be easily engineered into composite materials such as capsules as absorbents and thin films as membranes for gas separations. We create new interfaces for gas-liquid reactions and study their applications for CO2 filtration from air.
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Electrochemical Reduction of Carbon Dioxide
The electrochemical reduction of carbon dioxide is the 146-year-old, still an unresolved, challenge that was first studied in 1870 by M. E. Royer in Paris. It was considered that the only significant products in aqueous solutions were formic acid (HCOOH) and formates (HCOO-) of alkali metals with the highest current densities (> 90 %) achievable with mercury or amalgam (alloys of mercury and metals) electrodes. Despite the progress thereafter, the process still requires to be optimized for selectivity and efficiency. We study the role of ILs in electroreduction of CO2 in order to reduce the energy requirement for the process.