Galvanic cell measurements on a fast proton conducting complex perovskite electrolyte

✍ Scribed by Yang Du; A.S. Nowick

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 601 KB
• Volume: 91
• Category: Article
• ISSN: 0167-2738
• DOI: 10.1016/s0167-2738(96)00409-2

✦ Synopsis

The proton conducting Ba,Ca, ,,Nb,,,O,_, complex oxide electrolyte is shown to have proton conductivity a, > lo-' S/cm with transport number t, > 0.98 at 600°C. Concentration cell measurements up to 800°C with different gases show no sign of residual electronic conduction with a total ionic transport number, t, + t,, that is nearly unity. Further, it is found that only l/3 of the oxygen-ion vacancies, i.e. those that are replaceable by protons, participate in the conduction process, while the remaining deeply trapped Vi are virtually immobilized. With an electrolyte disc of 1 .O mm thickness, a hydrogen fuel cell operating at 500-600°C is shown to generate an open circuit voltage of 1.0 V and short circuit current density near 130 mA/cm*. Also, no electrolytic degradation with respect to the cell EMF was detected after operation in 0, or CO/CO, gases for more than 100 h. These qualities make the compound an excellent candidate as a solid oxide electrolyte for hydrogen fuel cells, humidity/hydrogen sensors and pumps.