12‐Crown‐4 Ether‐Assisted Enhancement of Ionic Conductivity and Interfacial Kinetics in Polyethylene Oxide Electrolytes

Abstract

Described below are the results of our investigations of the electrical and electrochemical properties of thin films of polyethylene oxide (PEO) electrolytes [with and without 12‐Crown‐4 ether (12Cr4)] as a function of temperature and in the frequency regime 100 kHz–0.1 Hz. These measurements were made on electrolytes containing , or salts. At a given temperature, the bulk conductivity, σ (S cm−1), for a particular salt, depends on the 12Cr4 concentration, with σ reaching a maximum for a ratio of 12Cr4 to Li of 0.003. Of the three salts studied, σ is the highest for for the same 12Cr4 ratio. The ac and dc measurements yield a lower charge transfer resistance for 12Cr4‐incorporated samples than for samples without. Plating/stripping of Li occurs at a potential closer to Li+/Li for 12Cr4 samples. The conductivities of thin (100 μm) and thick (400 μm) films are similar. The observation of a >45° spur at the low‐frequency regime in the ac impedance measurements on and electrolytes conditioned at 40°C overnight has been explained in terms of a constant phase angle element.