Large grain sized and high grain boundary conductive BaZr0.1Ce0.7Y0.2O3-δ (BZCY) proton-conducting electrolytes for solid oxide fuel cells by Cu doping

Grain boundary resistance is one of the main factors inhibiting the electrical properties of BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY) proton conduction electrolytes for solid oxide fuel cells (SOFCs). The Cu-doping strategy is applied to improve the electrical performance of grain boundary by promoting the grain growth and reducing the grain boundary blocking effect. For BaZr 0.1 Ce 0.7 Y 0.2-x Cu x O 3-δ (BZCYCu x , x = 0, 0.025, 0.050, 0.075, 0.100), the largest average grain size is 11.64 μm, which is approximately 5 times that of the BZCY electrolyte without Cu doping (2.13 μm). The optimized electrical performance is 1.64 × 10 −2  S cm −1 at 700 °C in moist air, which is twice that of BZCY. This is mainly attributed to the enhanced grain boundary conductivity by appropriate Cu doping, while BZCYCu 0.075 has the highest w / d g (0.733) and a relative low Δ φ (0) (0.201). The anode-supported cell shows a peak power density of 810 mW cm −2 at 700 °C in moist H 2 (as fuels) and ambient air (as oxidants).