Preparation and electrochemical properties of strontium doped Pr2NiO4 cathode materials for intermediate-temperature solid oxide fuel cells

Abstract

Pr2−xSrxNiO4 (PSNO, x = 0.3, 0.5 and 0.8) cathode materials for intermediate-temperature solid oxide fuel cell (IT-SOFC) were synthesized by a glycine-nitrate process using Pr6O11, Ni(NO3)2·6H2O and SrCO3 powders as raw materials. Phase structure of the synthesized powders was characterized by X-ray diffraction analysis (XRD). Microstructure of the sintered PSNO samples was observed and thermal expansion coefficient (TEC) and electrical conductivity were investigated. Electrochemical impedance spectroscopy (EIS) measurement of the PSNO materials on Sm0.2Ce0.8O1.9 (SCO) electrolyte was carried out, and single cells based on the PSNO cathodes were also assembled and their performances were tested. The results show that the synthesized PSNO powders have pure K2NiF4-type structure and the PSNO materials are chemically stable with Sm0.2Ce0.8O1.9 (SCO) electrolyte. The sintered PSNO samples have porous and fine microstructure with pore size smaller than 1 μm. Average thermal expansion coefficient of the PSNO materials is about 12–13 × 10−6 K−1 at 200–800 °C and the electrical conductivity is in the range of 70–120 Scm−1 at 800 °C. Area specific resistance (ASR) of the Pr2−xSrxNiO4 materials on SCO electrolyte is 0.407 Ωcm2, 0.126 Ωcm2 and 0.112 Ωcm2 for x = 0.3, 0.5 and 0.8 at 800 °C, respectively. Maximum open circuit voltage (OCV) and power density of the single NiO-SCO/SCO/PSNO cells are 0.75 V and 298 mWcm−2 at 700 °C, respectively, which indicates that Pr2−xSrxNiO4 may be a potential cathode material for IT-SOFC.