Polymer electrolytes composed of poly(acrylonitrile-co-lithium methacrylate) (P(AN-co-LiMA), PAN ionomer), ethylene carbonate (EC), and LiClO4 salts have been prepared. The polymer electrolytes based on the PAN ionomer with 4 mol% LiMA content exhibited ionic conductivities of 1.9 x 10(-3) S/cm at 25 degrees C and 2.4 x 10(-4) S/cm at -10 degrees C when only EC was used as a plasticizer. The interfacial resistance behavior between the lithium electrode and the PAN ionomer based polymer electrolyte has also been investigated and compared with that between the lithium electrode and the PAN based polymer electrolyte. The PAN ionomer based polymer electrolytes showed good interfacial resistance stability, while the PAN based polymer electrolytes could not attain a stable interface with the lithium electrode. The retardation of the passivating layer growth and the maintenance of the stable contact between the polymer electrolyte and the electrode seemed to be the principal reasons for the stable interfacial resistance of the polymer electrolytes based on the PAN ionomer. (C) 2000 Elsevier Science Ltd. All rights reserved.