Investigations on Electrochemical Performance of a Proton-Conducting Ceramic-Electrolyte Fuel Cell with La_0.8Sr_0.2MnO₃Cathode

The performance of a proton-conducting ceramic-electrolyte fuel cell (PCFC) with BaCe 0.85 Y 0.15 O 3-δ (BCY15) electrolyte, NiO-BCY15 anode and La 0.8 Sr 0.2 MnO 3 (LSM) cathode is analyzed in different gas conditions in 600–750°C range. The distribution of relaxation time (DRT) analysis of the electrochemical impedance spectroscopy (EIS) data obtained by varying the gas-flow rate, water vapor pressure ( p H 2 O) and oxygen partial pressure ( p O 2 ) is performed to identify the major electrode sub-processes involved in overall electrode reactions. The study of variations in cathodic p O 2 shows that the cathodic polarization due to the charge transfer reaction is the major contributor toward the overall electrode polarization resistance. The effect of electrolyte thickness on the fuel cell performance is also studied and a peak power density of ∼0.76 W⋅cm −2 at a current density of ∼1.95 A⋅cm −2 is achieved at 750°C with 8 μm thick electrolyte. The PCFC shows stable performance without any sign of material degradation during the long term operation at a fixed input current for 100 h. The fuel cell performance is compared with those of similar PCFCs with Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF5582), LSM-GDC, and LSM-BCY15 as cathodes, and possible reasons for the observed difference is discussed in terms of the nature of their conductivity.