Studying Voltage Stability of Polymer Electrolyte on Planar Metal Electrodes

Alexander Rausch, Daniel Hallinan Jr.

Abstract

Lithium batteries offer high energy density, high capacity, and long cycle life. However, these batteries use dangerous organic solvents in the electrolytes that can lead to malfunction, fires, and explosions. Polymer electrolytes are being used to replace these dangerous organic solvents as safer alternatives. In order for polymer electrolytes to become commercially feasible, they must be stable at high voltages. This project aims to determine the voltage stability of solid polymer electrolyte with different metal current collectors for use in solid-state lithium batteries. In particular, it focuses on poly(ethylene oxide) (PEO) doped with lithium bis-triflouromethanesulfonimide salt (LiTFSI) as the electrolyte at a molar ratio of 0.085 mol(Li⁺)/mol(EO). Copper, aluminum, and gold are used as the various working electrodes, and lithium is used as the counter electrode. Impedance spectroscopy is used to verify that the half-cells are well assembled by comparing the conductivity to literature values. Voltammetry is used to characterize the voltage stability of the electrolyte in the different half-cell assemblies. The results of these experiments will help determine battery materials that allow for better voltage stability in solid state batteries.