sri international has synthesized and tested new, dimensionally stable polymer electrolytes for high energy density rechargeable lithium batteries. we have prepared semi-interpenetrating networks of sulfur-substituted polyethyleneoxide with tetmethylorthosilicate (teos). the in situ hydrolysis of teos produces a mechanically stable three-dimensional network that entangles the polymer electrolytes and makes the film dimensionally flexible and stable. with this approach, the best dimensionally stable polymer electrolyte of this type produced so far, has a room temperature lithium ion conductivity of 7.5 (times) 10(sup (minus)4) s cm(sup (minus)1). another type of solid polymer electrolytes, polydiacetylene-based single-ion conductors with high room temperature proton conductivity were also developed. ne best conductivity of these polymers is two orders of magnitude higher than that of nafion under comparable experimental conditions. with further appropriate chemical modification, the new polymers could be used in fuel cells