Formation of a passivating film at the lithium-PEO-LiCF3SO3 interface

The formation of a passivating film on lithium electrodes is demonstrated using ac impedance analysis. The film is formed by an electrochemical reaction between the lithium electrode and the electrolyte, which consists of poly (ethylene oxide) and LiCF₃SO₃. Effects of the salt concentration in the electrolyte and temperature on the nature and conductivity of such films are described. Data obtained from the literature for equivalent systems was interpreted according to the proposed film formation mechanism. The rate-determining step in the dissolution or deposition process of the lithium may, in some cases, be defined by the interphase film.