Optimization and Development of Sodium-based Electrolytes for Energy Storage Devices

Energy storage devices have undergone development for decades. Much of the research is focused on the improvement of energy density by developing existing electrodes and investigating novel electrode materials. This has led to the overall improvement of traditional lithium-ion batteries, but also the discovery of new energy storage devices such sodium-ion batteries, redox flow batteries, solid electrolyte-based batteries, and many more. As the field expands, fundamental research is necessary to fully ascertain the validity of these novel systems for long term success. One of the most important components to all electrochemical energy storage devices such as batteries and supercapacitors is the electrolyte that allows for the conduction of ions. An ideal electrolyte needs a high ionic conductivity, high chemical stability, low cost, and works well in the desired operating conditions of the device its housed in. Developing an electrolyte that has all these properties is rare, but through communitive research, many electrolyte systems have found uses in niche and broad applications.

My dissertation research is focused on developing electrolyte for sodium-based systems both batteries and supercapacitors. Though supercapacitors differ from batteries in many ways, the fundamental properties of the electrolyte are important for both applications. Thermal stability of the electrolyte has become a growing concern due to the varied working environments of electronic devices. The work I present studied additives for both high temperature stability and low temperature stability in non-faradaic conditions to isolate the effects of temperature on the electrolytes during operation. The second scope of my work is studying nonaqueous redox flow batteries and optimizing their working conditions through electrolyte and system development. All this work was accomplished using a combination of electrochemical techniques and characterization techniques. The combination of these techniques has provided enough evidence to show effects of additives on the electrolyte system for thermal stability and for overall device improvement in the redox flow batteries. The work from this dissertation will progress the communal knowledge of the benefits and limitations of the electrolyte systems in my research.