Poly(ethylene oxide) (PEO)-coated separators were prepared by coating PEO onto a microporous polyethylene (PE) separators. Highly conductive electrolytes were prepared by soaking them in an electrolyte solution. The uptake of the electrolyte solution and the ionic conductivity of the PEO-coated separator (PCS) after soaking in LiBF4-ethylene carbonate (EC)/dimethyl carbonate (DMC) were measured to be 76% and 1.0 x 10(-3) S/cm. respectively. With these PCSs, lithium-ion cells composed of mesocarbon microbead (MCMB) anode and LiCoO2 cathode were assembled, and their electrochemical performances were evaluated. (C) 2001 Elsevier Science B.V. All rights reserved.