Electrochemical properties of LnSr3-xCaxFe3-yByO10 (Ln = La, Pr and Sm; x = 0-1.0; B = Co, Ni and Cu; y = 0-1.5) for intermediate temperature solid oxide fuel cells

Abstract

To enhance the electrochemical performance of cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC) the Ruddlesden-Popper (RP) phases of LnSr3-xCaxFe3-yByO10 (Ln = La, Pr and Sm; x = 0-1.0; B = Ni, Co, and Cu; y = 0-1.5) was investigated and prepared by citric nitrate combustion method. Firstly, various Ca concentrations were added to the LaSr3-xCaxFe3O10-δ structure and it was found that the materials contained low Ca concentration provided the lower area specific resistance (ASR) and better electrochemical cell performance due to the enhance in conductivity and reduction of TEC. Secondly, the effect of Pr and Sm replacement for La in LaSr2.7Ca0.3Fe3O10-δ was evaluated. The electrochemical cell performance of Pr substituted materials was promoted with the reduction of ASR due to the increase of oxygen migration through the oxygen vacancy and the reduction of Fe. Thirdly, the substitution of Ni, Co and Cu for Fe in PrSr2.7Ca0.3Fe2.5B0.5O10-δ was studied. The electrochemical performance of Co and Cu substituted materials was enhanced while the ASR was reduced because the conductivity and oxygen diffusivity were increased. Lastly, the effect of Co concentration in PrSr2.7Ca0.3Fe3-yCoyO10-δ was evaluated. The increased Co concentration decreased the electrochemical performance with increasing of ASR due to the lowering oxygen mobility, and the TEC was significantly increased. Thus, among the oxides examined in this work, PrSr2.7Ca0.3Fe2.5Co0.5O10-δ cathode showed the best electrochemical performance of single cell IT-SOFC with the maximum power density of 481 mW.cm-2 and the lowest ASR of 1.18 Ω cm2.