Impedance Spectroscopy and Phase Structure of Polyether−Poly(methyl methacrylate)−LiCF₃SO₃ Blend-Based Electrolytes

Polymeric electrolytes obtained by the free radical polymerization of methyl methacrylate in a solution of LiCF 3 SO 3 in an ethylene oxide−propylene oxide copolymer are studied. These electrolytes exhibit ambient temperature conductivities up to 3 × 10 -5 S/cm. Impedance spectroscopy experiments performed in a symmetrical cell with two lithium electrodes show that the properties of lithium electrode−polymer electrolyte interface are improved after the in situ polymerization of methyl methacrylate in the electrolyte. The growth of the resistance of the passive layer formed on the electrode−electrolyte interface is suppressed. The impedance studies are coupled with FT-IR measurements which show that the fraction of contact-ion pairs is reduced in electrolytes for which limited growth of the resistance of the passive layers is observed.