Student Seminar: Polymer Electrolytes for Solid State Batteries and Beyond

Solid polymer electrolytes (SPEs) are emerging as key materials for next-generation solid-state batteries (SSBs) due to their intrinsic safety, mechanical flexibility, and ability to provide uniform electrode–electrolyte interfaces. Compared to conventional liquid electrolytes, SPEs eliminate risks associated with leakage, flammability, and chemical instability, while enabling uniform lithium plating and stripping that helps minimize dendritic growth. Their ability to form intimate interfacial contact with electrodes further enhances charge transport and overall cell reliability.

This seminar will discuss the fundamental properties and operational principles of polymer electrolytes. Key parameters such as ionic conductivity, transference number, electrochemical stability window, and mechanical modulus will be introduced as critical descriptors governing performance and safety. The mechanisms of ion conduction in polymer matrices will be evaluated using theoretical models, including Arrhenius behaviour and Vogel–Tammann–Fulcher (VTF) formalism, which describe the temperature dependence of conductivity and highlight the significant role of polymer chain dynamics in ion transport.

Several material and design challenges, including low room-temperature ionic conductivity, limited interfacial compatibility, and trade-offs between mechanical strength and ion mobility, will be discussed in detail. Strategies to address these challenges through polymer backbone engineering, side-chain functionalization, copolymerization, and incorporation of plasticizers or inorganic fillers will be explored to illustrate recent advances in enhancing conductivity and stability. These advancements highlight the importance of systematically understanding how molecular structure influences electrochemical performance. Finally, by understanding the structure–property–function relationships in polymer electrolytes, new molecular design principles and hybrid material strategies can be developed to advance safe, flexible, and sustainable electrochemical energy technologies.