Protic ionic liquid electrolytes in electrchemical energy storage

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With world energy consumption expected to increase by 50% and reaching 733 x 10^20 joules by 2030, there is a strong impetus for the development of clean, renewable energy sources such as solar- and wind-based electricity generation. Due to the non continuous energy generated by these sources, their use strongly relies on energy storage devices with high power and high energy density that will be able to supply electricity during off-hour operation. Electrochemical capacitors (EC) will play an important role in future energy storage due to their ability to store and deliver charge at higher power than batteries. Although EC based on metal oxide electrodes in particular possess very high specific capacitance which makes them promising storage devices, their energy densities are insufficient to meet future needs. Research on electrolyte interactions with the electrode materials in EC has been identified as a priority area where improvements could lead to significant progress and will be the focus of this research program. We propose the use of protic ionic liquids as replacement of water-based electrolytes in metal oxide EC. These ionic liquids are entirely composed of ions in a liquid state around ambient temperature, possess high thermal and electrochemical stability as well as a high concentration of protons. The proposed research program involves the use of PIL electrolytes in metal oxide capacitors, an idea that my group pioneered. The lack of fundamental understanding on the influence of electrolyte species on molecular interactions will be addressed by studying different ion structures to determine how electrolyte properties influence device performance. A particular attention will be given to the proton transport and activity in the electrolyte through electrochemical and NMR experiments. The effect of these properties on charge storage will be evaluated with several metal oxide electrodes both in half-cells and in prototype devices. The expected outcome and impact of the proposed research will be felt on both the fundamental and applied levels of the science of electrical energy storage, a field that is identified as a priority in Canada and many other countries.