The interface resistance between a lithium metal electrode and a polymer electrolyte has been measured for composite polymer electrolytes using various ceramic fillers with poly(ethylene oxide) (PEO) and lithium salts (LiX), The interface resistance depended on the properties of added fillers and lithium salts. The PEO with LiClO4 electrolyte contacted with lithium metal showed the high interfacial resistance of 1000 Omega cm(2) at 70 degreesC for 25 days. In contrast, the interface resistance between lithium metal and PEO with Li(CF3SO2)(2)N was as low as 67 Omega cm(2) after contacting at 80 degreesC for 30 days. The interface stability and the lithium ion conductivity were improved by addition of a small amount of ferroelectric BaTiO3 as the filler into the PEO-LiX electrolyte. (C) 2001 Elsevier Science B.V. All rights reserved.