Yttrium dependent space charge effect on modulating the conductivity of barium zirconate electrolyte for solid oxide fuel cell

Development of high proton conducting, chemically stable electrolyte for solid oxide fuel cell application still remains as a major challenge. In this work, yttrium (0, 5, 10, 15 and 20 mol%) doped barium zirconate synthesised by hydrothermal assisted coprecipitation exhibited highly crystalline cubic perovskite. The results demonstrate that the proton conductivity is higher than oxygen ion conductivity measured in the temperature range of 200-600 degrees C. The 20 mol% Y doped BaZrO3 exhibited higher protonic conductivity (6.1 mScm(-1)) with an activation energy 0.64 eV under the reducing atmosphere. The Mott -Schottky analysis carried out in hydrogen atmosphere at 200 degrees C revealed that the barrier height of doped BaZrO3 reduced from 0.6 to 0.2 V. The Schottky depletion layer width also decreased from 4 to 2 nm with the increase in yttrium concentration and the boiling water test showed good phase stability. Our study highlights the critical role of space charge in the grain boundary and its suppression with the increase in dopant concentration. The results demonstrate that Y doped BaZrO3 sintered at low temperature is a promising candidate as the electrolyte material for the intermediate temperature proton conducting solid oxide fuel cells. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.