Anode-supported fuel cell with promising Co-free (La,Pr)2(Ni,Cu)O4-based cathode

Abstract

La_1.5Pr_0.5Ni_0.4Cu_0.6O_4+δ (LPNC) and La₂NiO_4+δ (LN) oxides are applied and compared as cathodes in the anode-supported fuel cells with the Ce_0.8Sm_0.2O_2-δ (SDC) thin electrolyte. LPNC and LN samples are synthesized by citrate-nitrate method. Doping of LN with Pr and Cu leads to a reduction of the final annealing temperature down to 750 °C. The optimal sintering temperature for electrode fabrication is also reduced to 950 °C, compared to 1000 °C for undoped LN. Differential analysis of i-V characteristics (DiVA) for the studied LPNC/SDC/Ni-SDC fuel cells shows that potential drop with increasing current is mainly associated with ohmic losses and gas diffusion limitations at higher current densities. The contribution of the activation polarization increases when LPNC is replaced by LN indicating slower electrode reaction in the latter. Electrochemical Impedance Spectroscopy (EIS) studies show that the polarization resistance of the studied fuel cells is mainly determined by the cathode in the temperature range of 600–750 °C. Fuel cell tests reveal that LPNC has significantly higher ORR activity than undoped LN. The maximal power densities for the LPNC/SDC(28 μm)/Ni-SDC fuel cell are 1.46, 1.25, 0.94 and 0.62 W cm⁻² at 750, 700, 650 and 600 °C, respectively.