New polymer electrolytes based on poly(acrylonitrile-co-vinylimidazoline), P(AN-VI) were prepared and their chemical and physical properties were characterized by conductance, DSC, and solid state Li-7- and C-13 NMR measurements. Conductivity for the P(AN-VI)-based electrolytes was about 10(-4) S cm(-1) at 30degreesC and 10(-3) S cm(-1) at 60degreesC. Addition of the cascade nitrile compound, ED4CN {-[-CH2N(CH2CH2CN)(2)](2)} which acts as a plasticizer for polyacrylonitrile-based electrolytes, to P(AN-VI)-based electrolytes reduced their conductivities. Polarization behavior of a lithium electrode in the P(AN-VI)-based electrolytes was improved by the addition of ED4CN. Exchange current density of the lithium electrode in the P(AN-VI)-based electrolyte with ED4CN was one order of magnitude higher than that in the ED4CN-free P(AN-VI) electrolyte. Addition of ED4CN to the P(AN-VI)-based electrolyte changed the environment of the lithium ions in the electrolyte. Dominant coordination of the ED4CN molecules to the lithium ions was confirmed by Li-7 NMR measurements and increased the effective concentration of the lithium ions in the electrolytes. (C) 2003 Elsevier Science B.V. All rights reserved.