Preparation and characterization of highly active and stable NdBaCo0.8Fe0.8Ni0.4O5+δ oxygen electrode for solid oxide fuel cells

Abstract

In order to develop high active and stable oxygen electrode for intermediate temperature solid oxide fuel cells (IT-SOFCs), NdBaCo0.8Fe0.8Ni0.4O5+δ (NBCFN) oxygen electrode was successfully prepared by sol-gel method. The NBCFN sample formed a double perovskite structure after calcination at 1100 °C for 10 h. The NBCFN electrode and La0.9Sr0.1Ga0.83Mg0.17O3-δ (LSGM) electrolyte has good chemical compatibility below 950 °C. Compared with NdBaCo2O5+δ, the average thermal expansion coefficient (TEC) of NBCFN sample was 17.2 × 10−6 K-1 at 30 °C - 850 °C in air and decreased by 30%. The conductivity of NBCFN sample exhibited p-type semiconductor conduction and reached 441.8 S cm−1 at 800 °C. The polarization impedance (RP) of NBCFN oxygen electrode on LSGM electrolyte reached 0.055 Ω cm2 at 700 °C. The charge transfer process of NBCFN oxygen electrode was mainly rate-limiting step. The RP of NBCFN oxygen electrode exhibited good stability in air during 200 h test. At 800 °C, the NBCFN oxygen electrode on 300μm-thick LSGM electrolyte reached 1042 mWcm−2 at fuel cell mode and current density was 0.9 A cm−2 at 1.3 V under the electrolysis cell mode, respectively. These results primarily indicated that NBCFN oxygen electrode had good electrochemical performance for IT-SOFCs.