(546d) Unique Mixing Behaviors of Nanoscale Fluid-Based Electrolytes for Sustainable Energy Storage

Although the costs associated with renewable energy technologies continue to decrease at a fast rate, they continue to face intermittency and storage challenges. It is now possible to store this excess renewable energy in the form of chemicals and fuels through electrochemical CO2 reduction or in the form of redox flow batteries (RFBs). The electrochemical conversion of CO2 remains challenged by the CO2 solubility in aqueous solutions and the energy density of redox flow batteries is limited by redox species solubility. Therefore, novel reactive materials are currently being explored as additives to aqueous and non-aqueous electrolytes in order to improve target species solubility and/or enhance reaction rates. Polymer functionalized nanoparticles are a promising class of electrolyte additives due to their thermal stability and chemical tunability. Interestingly, grafted polymers have been shown to change their conformations in response to their environment (temperature, pH, salt concentration), thus allowing them to be engineered to capture and subsequently release target species. In this study, Nanoparticle Organic Hybrid Materials (NOHMs)-based fluids have been designed as hybrid electrolyte systems for energy storage applications. The development of NOHMs-based electrolytes requires a fundamental investigation into the structuring and organization of these complex nanoscale fluids. A study of the mixing behaviors of NOHMs with a variety of secondary fluids has revealed that physical properties such as hydrodynamic size, viscosity and diffusion coefficient are highly dependent on the chemical nature and size of the secondary fluid molecule. Additionally, it was discovered that the viscosity and the diffusion coefficient of the untethered polymer were found to scale according to theoretical predictions for the semi-dilute unentangled regime, while this was not observed for NOHMs-based fluids. Lastly, the CO2 solubility of NOHMs-based electrolytes has been measured and a change in the selectivity of the CO2 reduction reaction has been identified in the presence of these nanoscale electrolytes. The results of this work provide important insights into the design and development of a novel reactive medium for energy storage applications.