Committee Members:

Dr. Gleb Yushin, Advisor, MSE

Dr. Preet Singh, co-Advisor, MSE

Dr. Faisal Alamgir, MSE

In-situ Polymerization of Methacrylate based Solid Polymer Electrolyte for Solid State Lithium

ABSTRACT

In the wake of global transition to renewable energy, the demand for energy storage devices has grown exponentially. With electric vehicles (EVs) becoming mainstream, energy dense lithium-ion batteries (LIBs) are the need of the hour. Conventional liquid electrolyte batteries for LIBs may pose a safety hazard due to the use of flammable organic electrolytes with high vapor pressure. Solid state batteries (SSB) may become a solution to this problem if they mitigate the flammability issue and offer sufficiently high energy and power densities required for applications in the electric mobility sector. Conventional methods of processing solid polymer electrolytes (SPEs) and their incorporation into LIBs involve fabricating the electrode(s) and the separator membrane separately. These methods are heavily reliant on toxic solvents and are time and energy intensive processes, which makes a hurdle to commercialization. This thesis employs in-situ polymerization process, which is a one-step process of infiltration of SPE precursors into LIB stack followed by the polymerization and formation of the SPEs. Eliminating the use of solvents and reducing fabrication time makes this technique more attractive for a commercial deployment. A novel SPE is being explored in this thesis. The synthesis of the polymer has been explained and characterizations have been performed to understand thermal and electrochemical stability of the SPE. Systematic studies have been performed to investigate the evolution of resistance and stability of the solid electrolyte interphase (SEI) in contact with electrodes. Finally, the long-term cycling and rate performance of the SPE incorporated into commercial battery materials, such as lithium iron phosphate (LFP) and lithium titanate (LTO) have been evaluated.