Enhanced sintering ability and electrochemical performance of Gd0.1Ce0.9O1.95 composited with (Dy0.2Zr0.05Bi0.75)2O3 for low-temperature solid oxide fuel cells

Abstract

By compositing cerium oxide (Gd0.1Ce0.9O1.95, GDC) with the dysprosium-zirconium co-doped bismuth oxide (Dy0.2Zr0.05Bi0.75)2O3, or DZSB, a novel DZSB-GDC composite electrolyte is developed, which has excellent sintering ability and ionic conductivity. Reverse coprecipitation is used to prepare nano composite electrolyte powders, and the sintering and electrical properties with varying DZSB composite ratio are examined. After sintered at 1200 °C for 10 h, all composite electrolyte pellets can achieve densities of more than 95 %. Furthermore, as the DZSB ratio increases, the densification rate increases and the starting temperature of the densification stage decreases. 10DZSB-GDC shows the highest conductivity (σt) and has an activation energy of 0.92 eV below 550 °C, which is 8.9 % lower than that of pure GDC. At 400 °C, the grain boundary conductivity of 10DZSB-GDC was 113.8 times that of pure GDC. The ionic conductivity of 10DZSB-GDC remain stable at 0.015 S cm−1 at 600 °C for 4200 h without any decay. The open-circuit voltage and peak power density of 10DZSB-GDC based cell are 0.914 V, and 441.1 mW cm−2 at 750 °C, which is 1.1 and 2.1 times that of GDC-supported cells, respectively. This indicates that 10DZSB-GDC is a promising electrolyte material for low-temperature solid oxide fuel cells.