Novel SrSc_0.2Co_0.8O_3-δ as a cathode material for low temperature solid-oxide fuel cell

The SrSc_0.2Co_0.8O_3-δ (SSC) perovskite was investigated as a cathode material for low temperature solid-oxide fuel cell. The material showed an almost linear thermal expansion from room temperature to 1000 °C in air with the average thermal expansion coefficient of only 16.9 × 10^-6 K^-1. The Sc-doping made the absence of Co⁴⁺ in SSC, which resulted in not only dramatically reduced thermal expansion coefficient but also extremely high oxygen vacancies concentrations in the lattice at low temperature. The area specific polarization resistance was 0.206 Ω cm² for SSC at 550 °C, which is about 52% lower than the value of a Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ-based cathode. A peak power density as high as 564 mW cm^-2 was obtained at 500 °C based on a 20 μm thick Sm_0.2Ce_0.8O_1.9 electrolyte by adopting SSC cathode.