Evaluation of La_1−xSr_xNi_0.4Fe_0.6O_3-δ as Electrode Materials for Direct Methane Symmetrical Solid Oxide Fuel Cells

Abstract

In this work, La1−xSrxNi0.4Fe0.6O3-δ (0 ≤ x ≤ 0.2) oxides were synthesized and employed as the identical electrode of direct methane symmetrical solid oxide fuel cell (SSOFC). In addition, the phase structure, redox stability, electrical conductivity, chemical compatibility, and thermal expansion of La1−xSrxNi0.4Fe0.6O3-δ oxides were evaluated. The La2NiO4 phase occurs when the amount of doped Sr rises to 0.2. The composition of La0.9Sr0.1Ni0.4Fe0.6O3-δ (LSNF9146) boasts the highest conductivity of 463 S cm−1 with lowest activation energy of 0.066 eV as well as a relatively large thermal expansion coefficient. After treatment in methane for 10 h, the LSNF9146 oxide exhibits 33% lower carbon deposition than the LaNi0.4Fe0.6O3-δ (LNF46) oxide. Moreover, the impregnated LSNF9146 electrode demonstrates lower polarization resistance in both air and methane atmospheres. SSOFCs with impregnated LSNF9146 and LNF46 identical composite electrodes have the maximum power densities of 233 and 170 mW cm−2 at 850 °C in methane, respectively. These results prove that LSNF9146 is a promising symmetrical electrode with high catalytic activity, good redox stability, and coking resistance to direct methane SSOFCs.

Keywords

• solid oxide fuel cells
• symmetrical electrodes
• La_1−xSrxNi_0.4Fe_0.6O_3-δ
• impregnation
• direct methane