Studies On The Ionic Conduction And The Fuel Cell Performance Of BaCeO₃--based Ceramics

Fourteen ceramic samples of the two series of BaxCeo.gYo.aCb-.and BaxCeo.gSmo.2O3.u (xl) prepared by high temperature solid-stated reaction are chosen for this dissertation. The made research works are as follows: ?crystal phase analysis by XRD method (2) studies on the effects of the RE3+ dopants, the temperatures (600-1000 C) and the experimental atmospheres on the ionic conduction in the samples by using gas concentration cells (3) study on the discharging performance of the hydrogen-air fuel cell. The following results have been clarified : (1) All of the ceramic samples show a single phase of orthorhombic perovskite of BaCeO3. (2) Under high temperature and hydrogen -containing atmosphere, the former is almost pure proton conductor whereas the latter shows relatively weak protonic conduction. (3) Under high temperature and oxygen-containing atmosphere, both of the two series are mixed oxide-ionic and electronic conductors.(4) hydrogen-air fuel cells with them as solid electrolyte and Pt or Pt-Rh alloy as electrode material have stable discharging performances but have distinguished difference in their maximum short-circuit current density and the maximum power output density. In a word, the electrical performances of the former are superior to the latter. Particularly, Bai.oaCeo.sY0.2O3-a, shows the highest cell performance with the maximum short-circuit current density of 435mA cm-2 and the maximum power output density of 0.11W cm-2 under 1000C among the investigated samples.