Effect of doping strategy on electrochemical performance of grain boundaries of complex perovskite proton conductor Ba3Ca1.18Nb 1.82O_δ

In this study, the electrical conductivity and electrochemical performance of Ba 3 Ca 1.18 Nb 1.82 O 9_s were improved by substituting niobium (Nb) element with bismuth (Bi) and ytterbium (Yb) elements. Three different proton conductors, namely, Ba 3 Ca 1.18 Nb 1.82 O 9_s (BCN), Ba 3 Ca 1.18 Nb 1.72 Bi 0.1 O 9_s (BCNB), and Ba 3 Ca 1.18 Nb 1.72 Yb 0.1 O 9_s (BCNYb) were prepared by solid state sintering. The electrochemical performance of BCNYb was found to be the best at 400-800 degrees C in the wet atmosphere. Their ion transport properties were studied by using the defect equilibrium model. The results show the improvement in proton conductivity of BCNYb. Analysis of distribution of relaxation time reveals the improvement in the grain boundary properties of BCNYb. Single cells were prepared with BCN, BCNB, and BCNYb electrolytes, and the performance of the resulting fuel cells was tested. The BCNYb-based fuel cell shows excellent electrochemical performance, indicating its promising potential as a solid-state electrolyte with excellent properties.