Enabled fast cathode kinetics for intermediate-temperature solid oxide fuel cell with improved CO2 poisoning robustness: La2NiO4 surfaced-modified SrCo0.8Nb0.1Ta0.1O3-δ composite

Abstract

One challenge facing the development of solid oxide fuel cell (SOFC) is the fast cathode degradation due to poisoning of common contaminants in ambient air such as CO2. Here, we propose an effective strategy to enhance CO2-tolerance of perovskite SrCo0.8Nb0.1Ta0.1O3-δ (SCNT) cathode through surface modification with alkaline free layered perovskite La2NiO4 (LNO) particles. Appropriate modification extended active areas toward oxygen reduction reaction (ORR) with the intrinsically high oxygen surface exchange coefficient of LNO, which reduced the polarization resistance (Rp) for nearly 33% for SCNT-10LNO (10 wt% LNO) cathode (Rp of 0.12 Ω cm2 at 600 °C). Furthermore, SCNT-10LNO cathode exhibited less catalytic activity attenuation than blank SCNT in CO2 atmosphere. At 500 °C, Rp increasing rate of SCNT-10LNO is only 5.95 × 10−4 Ω cm2 min−1 in 10% CO2 atmosphere, which is one order of magnitude smaller than that of SCNT. The enhanced CO2-tolerance can be ascribed to the less stable lanthanum carbonates than strontium carbonate, as evidenced by the calculated chemical potential of CO2 for decomposition of corresponding carbonates. The LNO modification synergistically enhanced ORR kinetics and CO2 poisoning robustness for perovskite SCNT, which highlight the potential of SCNT-10LNO as a highly promising cathode for SOFC.