Preparation and electrochemical characterization of Ruddlesden-Popper oxide LaNiO cathode for IT-SOFCs by sol-gel method.

LaNiO oxide was synthesized as a cathode material for intermediate-temperature solid oxide fuel cells by a facile sol-gel method using a nonionic surfactant (EO)106(PO)70(EO)106 tri-block copolymer (F127) as the chelating agent. The crystal structure, electrical conductivity, and electrochemical properties of LaNiO were investigated by X-ray diffraction, DC four-probe method, electrochemical impedance spectra, and I-V measurements. The LaNiO cathode showed a significantly low polarization resistance (0.26 Ω cm) and cathodic overpotential value (0.037 V at the current density of 0.1 A cm) at 750 °C. The results measured suggest that the diffusion process was the rate-limiting step for the oxygen reduction reaction. The LaNiO cathode revealed a high exchange current density value of 62.4 mA cm at 750 °C. Furthermore, an anode-supported single cell with LaNiO cathode was fabricated and tested from 650 to 800 °C with humidified hydrogen (∼3 vol% HO) as the fuel and the static air as the oxidant. The maximum power density of 900 mW cm was achieved at 750 °C. [ABSTRACT FROM AUTHOR]