Enhanced electrochemical and transport properties of proton-conducting electrolytes through Y and Gd co-doping in BaCe0.6Zr0.2Y0.2-xGdxO3-δ

In this study, the impact of co-doping Y and Gd on the structure and electrical properties of BaCe_0.6Zr_0.2Y_0.2-xGd_xO_3-δ (x = 0, 0.05, 0.10, and 0.15; denoted as BCZY, BCZYG5, BCZYG10, and BCZYG15) perovskite proton conductors were systematically studied. The BCZYGx materials were synthesised via a solid-state reaction. The XRD results demonstrate that the Gd elements have been successfully incorporated into the lattice of the material phase, resulting in the formation of a single perovskite phase. The SEM and EDS results demonstrate that the doping of Gd can facilitate grain growth and enhance the material’s density. The electrical properties of BCZYGx materials are investigated by relaxation time distribution (DRT) and equivalent circuit scheme (ECS) based on the defect equilibrium model. The results demonstrate that the BCZYG5 exhibits the highest conductivity and proton transport number at 600 °C, which were 9.47 × 10^–3 S·cm⁻¹ and 0.88, respectively. The experimental results indicate that the co-doping strategy can effectively enhance the conductivity and proton transport number of the BCZYG5 proton conductor material. This paper presents a novel approach to optimising the performance of perovskite proton conductors, offering valuable insights for the development of high-performance protonic ceramic fuel cells.