A novel polymer electrolyte composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(vinyl pyrrolidone) (PVP), ethylene carbonate (EC), dimethyl carbonate (DMC), and LiBF4 salts has been prepared. The transport properties were measured including the conductivity, the salt diffusion coefficient, and the lithium ion transference number. The polymer electrolyte based on the blend of PVDF-HFP and PVP exhibited ionic conductivity of 0.4 mS cm(-1) at room temperature when PVP:PVDF-HFP:liquid electrolyte was about 1:10:18 by weight. The salt diffusion coefficient, cation transference number, and electrochemical window were determined by restricted diffusion experiment, steady state polarization, and linear sweep voltammetry method, respectively. The lithium ion battery with the polymer electrolyte based on the blend of PVDF-HFP and PVP was assembled and the initial coulombic efficiency was about 90%. (C) 2003 Elsevier B.V. All rights reserved.