An overview of our research is presented on developing composite polymer electrolytes (CPEs) based on low-molecular weight polyethylene oxide (PEO) (namely, poly(ethylene glycol) dimethyl ether), lithium salts (e.g. lithium triflate, lithium imide, etc.), and fumed silica. These CPEs demonstrate high room-temperature conductivites (>10(-3) S/cm), mechanical strength, and form stable interfaces with lithium metal as a result of the fumed silica. The surface groups on the fumed silica determine the mechanical properties of the CPE while the low-molecular weight PEO and lithium salt determine the ionic transport properties. These CPEs show promise as electrolytes for the next generation of rechargeable lithium batteries. (C) 2000 Elsevier Science S.A. All rights reserved.