Terahertz conductivity of polymer electrolytes

The polyethylene oxide (PEO)-based polymer electrolytes containing lithium salts pave the way for the development of safe lithium batteries with high energy storage capacity. Enabled by the flexibly vibrating polymer matrix, the Li-ion transport occurs via hopping along and between the polymer chains. Here, terahertz (THz) time-domain spectroscopy over a frequency range extending from 0.1 THz to 7 THz is applied to investigate the conduction properties of PEO-based electrolytes with lithium salts, and to elucidate the associated dependence of the THz conductivity on the content of the added lithium salt and the electrolyte temperature. It is remarkably found that the higher the observed THz vibrational activity of the electrolyte, the higher its technologically relevant ionic conductivity.