(420j) Designing Composite Polymer Electrolyte Interfaces for Stable Electrodes

Authors: 
Yang, G., The Aero-Propulsion, Mechatronics and Energy (AME) Center
Hallinan, D. T. Jr., Florida State University

Polymer electrolytes are promising materials for high energy density rechargeable batteries. However, typical polymer electrolytes are not electrochemically stable at the charging voltage of advanced positive electrode materials. Decomposition of polymer electrolyte would occur when the cathodic potential is above 4V. The initial goal of this project is to understand polymer electrolyte oxidation and design a polymer electrolyte/cathode interfacial layer to prevent such oxidation. This cathode and interfacial layer comprises inorganic metallic nanoparticles and organic protecting ligands. The interfacial layer must be permeable to ions and impermeable to electrons so that further oxidation of polymer electrolyte can be prevented

Currently, thin gold nanoparticle (Au NP) films are being studied. Au NPs have been chosen for their large surface-to-volume ratio to provide sufficient contact area and signal. In addition, gold is inert and hence non-reactive with most polymer electrolytes and lithium salts. Finally, it is facile to modify the surface. In our study, poly (ethylene oxide) (PEO) will serve as the polymer and lithium bis(trifluoromethanesulfonyl) imide salt (LiTFSI) will be the salt. Characterization of structure and conductivity of Au NP thin films with different length ligands will be presented. Electrochemical stability of polymer electrolyte as a function of ligand length will also be reported.