In this work, electrolytes for secondary batteries and fuel cells were investigated. Ionic liquids (ILs), for use as battery electrolytes, were formed using quaternary ammonium salts (Quats) and aluminum chloride. The room temperature (RT) carbonate fuel cell was demonstrated by modifying a commercially available anion exchange membrane, utilizing positive quaternary ammonium fixed sites, to transport carbonate. The charge density on the nitrogen and the symmetry of the Quat were demonstrated to be the dominant factors in determining the IL melting point (MP). The introduction of a benzyl ring was found to lower the MP of the ILs by increasing the size of the Quat, while disrupting its symmetry. ILs formed from asymmetric quaternary ammonium salts having three distinct groups were found to have lower melting points than those formed using Quats with two groups. Replacement of an alkyl group with a rigid ether linkage can lower the IL melting point. Assymetric alkyl substituted Quats were found to form more electrochemically stable, less viscous ILs than their benzyl substituted counterparts. The increased electrochemical stability is due to the smaller butyl chain being a worse leaving group than the benzyl group. Similarly, the smaller size of the alkyl substituted Quats results in the lower viscosities. Lithium and sodium can be reversibly deposited from neutral ILs following the addition of an additive (such as SOCl2). The additive disrupts the strong coordination between Na+, or Li+, and AlCl4-. Chlorinated compounds, such as chloroform-D and carbon tetrachloride, were demonstrated to catalyze the reversible reduction of sodium. When neutralized with lithium and sodium, reversible Li-Na alloys were deposited. The Li-Na alloy appears to suppress dendrite formation and could potentially be used as a metal based anode in a rechargeable Li battery. A novel room temperature carbonate fuel cell was constructed. The alkaline environment could eliminate the need for water in the oxidation of methanol. Cells were operated on hydrogen, 1M methanol, and pure methanol fuels. CO2 was produced at the anode and O2 and CO2 were necessary at the cathode for operation, indicating that carbonate was the conducting ion.

Ion-exchange membranes, conventionally utilized in separation processes of electrolyte solutions, are electroactive polymers that display a unique coupling between electrochemistry and mechanics. Previous experimental studies have demonstrated the possibility of actuating cation-exchange membranes in salt solution through the application of a remote external electric field. The use of anion-exchange membranes as contactless actuators, however, has never been documented and little is known about the physics of their actuation. Here, it is reported for the first time the possibility of contactless actuating anion-exchange membranes in salt solutions; such an actuation is mediated by the selection of anions in the external salt solution and the membrane. Actuation is attributed to the physical phenomenon of solvation, the interaction between ions and solvent in solution. Contrary to previous studies with cation-exchange membranes, the results show that anion-exchange membranes consistently bend toward the anode. The integration of anion-exchange and cation-exchange membranes in composites promises innovative programmable contactless actuators, with applications in underwater robotics and biomedical engineering.

Lack of energy storage is a key issue in the development of renewable energy sources. Most renewables, especially solar and wind, when used alone, cannot sustain a reliably constant power output over an extended period of time. These sources generally generate variable amounts of power intermittently, therefore, an efficient electrical energy storage (EES) method is required to better temporally balance power generation to power consumption. One of the more promising methods of electrical energy storage is the unitized regenerative fuel cell (UFRC.) UFRCs are fuel cells that can operate in a charge-discharge cycle, similar to a battery, to store and then to subsequently release power. Power is stored by means of electrolysis while the products of this electrolysis reaction can be recombined as in a normal fuel cell to release the stored power. A major advantage of UFRCs over batteries is that storage capacity can be decoupled from cell power, thus reducing the potential cost and weight of the cell unit. Here we investigate UFRCs based on hydrogen-halogen systems, specifically hydrogen-bromine, which has potential for improved electrode reaction kinetics and hence cheaper catalysts and higher efficiency and energy density. A mathematical model has been developed to analyze this system and determine cell behavior and cycle efficiency under various conditions. The conventional H2-Br2 URFCs, however also so far have utilized Pt catalysts and Nafion membranes. Consequently, a goal of this work was to explore alternate schemes and materials for the H2-Br2 URFC. Thus, three generations of test cells have been created. The first two cells were designed to use a molten bromide salt, ionic liquid or anion exchange membrane as the ion exchange electrolyte with the liquids supported on a porous membrane. This type of system provides the potential to reduce the amount of precious metal catalyst required, or possibly eliminate it altogether. Each cell showed improvement over the previous generation, although the results are preliminary. The final set of results are promising for anion exchange membranes on a cost basis compared Nafion. Another promising energy storage solution involves liquid methanol as an intermediate or as a hydrogen carrier. An alternative to storing high-pressure hydrogen is to produce it on-board/on-site on demand via a methanol electrocatalytic reformer (eCRef), a PEM electrolyzer in which methanol-water coelectrolysis takes place. Methanol handling, storage, and transportation is much easier than that for hydrogen. The hydrogen produced via methanol eCref may then be used in any number of applications, including for energy storage and generation in a standard H2-O2 PEM fuel cell. The mathematical modeling and analysis for an eCref is very similar to that of the HBr URFC. In this work, a comprehensive model for the coelectrolysis of methanol and water into hydrogen is created and compared with experimental data. The performance of the methanol electrolyzer coupled with a H2-O2 fuel cell is then compared for efficiency to that of a direct methanol fuel cell data and was found to be superior. The results suggest that an efficient and small paired eCRef-fuel cell system is potentially be a cheaper and more viable alternative to the standard direct methanol fuel cell. Both the H2-Br2 URFC and the methanol eCref in combination with a H2-O2 fuel cell have significant potential to provide higher energy efficiency and energy density for EES purposes.