Investigation on thermal, electrical, and electrochemical properties of scandium-doped Pr_(0.6)Sr_(0.4)(Co_(0.2)Fe_(0.8))_((1-x))Sc_xO_(3_δ) as cathode for IT-SOFC

摘要

A systematic study and evaluation were performed on the effect of scandium doping at the B site of Pr_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) (PSCF) on key material properties as cathode for intermediate temperature solid oxide fuel cells (IT-SOFC). The doped products Pr_(0.6)Sr_(0.4)(Co_(0.2)Fe_(0.8))_((1-x))Sc_xO_(3-δ) (PSCFS_X , x=0.0-0.2) retained perovskite structure confirmed by X-ray diffraction, and their particles were smaller than the non-doped materials as evidenced by TEM. The electrical conductivity (EC) of PSCFS_X decreased with increasing Sc_(3+) content, but EC values were still larger than 100 S cm~(-1) in temperature range of 300-800 ℃ as x < 0.1. The thermal expansion coefficients (TEC) of PSCFS_X were observed to generally decrease with increasing x especially at lower temperature range of 50-600 ℃. In addition, the AC impedance revealed better electrochemical performance of PSCFS_X cathode as x < 0.1 than that of the undoped sample PSCF. Therefore, PSCFS_X (x ≤ 0.1) shows some potential as cathode electrode for IT-SOFC. The function of Sc~(3+) dopant was tentatively elucidated and discussed.