Development of New Fast Proton Conducting Chalcogenide Glassy Electrolytes

Abstract

SThe pubili reporting burden for this coilsotion of information is estimated to average 1 hour per responoe, including the time for reviewing instructions,, eworhing existing date soures., gtherun and mantanig the data needed, end completing and reviewin the coilection of information. Send cormlmets regarding this burden estmat or any other aspect of this aoiiection of iformaton, notding sug•m4gestons for reducig the rdenfe Ames, IA 50011-2300 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)Office of A new research project was initiated to investigate whether high proton conductivity chalcogenide glasses could be prepared by doping base chalcogenide glasses, like glass B2S3 with a proton source, like H2S to yield proton conducting membranes for use in intermediate temperature proton exchange membrane fuel cells. While it will be shown below that indeed proton doped chalcogenide glasses could be prepared over wide ranges of compositions from a number of different base chalcogenide glasses, including B2S3, the proton conductivity for all of these glasses and in some cases polycrystals, was always quite low, rarely exceeding 10-5 (S/cm) at 100 oC. In addition, the proton doped glasses and ceramics exhibited limited thermal stability such that these materials thermally decomposed rapidly losing H2S, the proton source, above 100 oC and for this reason had very limited usefulness above l00oC. A new research project was initiated to investigate whether high proton conductivity chalcogenide glasses could be prepared by doping base chalcogenide glasses, like glass B 2 S3 with a proton source, like H 2 S to yield proton conducting membranes for use in intermediate temperature proton exchange membrane fuel cells. While it will be shown below that indeed proton doped chalcogenide glasses could be prepared over wide ranges of compositions from a number of different base chalcogenide glasses, including B 2 S 3 , the proton conductivity for all of these glasses and in some cases polycrystals, was always quite low, rarely exceeding 10-5 (S/cm) at 100 °C. In addition, the proton doped glasses and ceramics exhibited limited thermal stability such that these materials thermally decomposed rapidly losing H 2 S, the proton source, above 100 TC and for this reason had very limited usefulness above 100°C. IS. SUBJECTProtonated thioborate phases were successfully prepared by reacting vitreous B 2 S 3 (v-B 2 S 3 ) with H 2 S. This reaction yielded polycrystalline meta-thioboric acid (HB-S 2 ) 3 as vapor condensates.