Enhanced ORR Activity of A-Site-Deficient SrCo_0.8Nb_0.1Ti_0.1O_3−δ as a Bifunctional Air Electrode for Low-Temperature Solid Oxide Fuel Cells

Abstract

Solid oxide fuel cells (SOFCs) working at intermediate and low temperatures (≤650 °C) demonstrate tremendous potential benefits including their ease of manipulation, improvement in durability, and utilization of metallic interconnects. However, the sluggish oxygen reduction reaction (ORR) of air electrodes at lower temperatures is the main reason for constraining their supply of power. In this work, an A-site-deficient perovskite Sr0.95Co0.8Nb0.1Ti0.1O3−δ (S0.95CNT) has been developed as a bifunctional air electrode for both oxygen-ion-conducting SOFCs (O-SOFCs) and proton-conducting SOFCs (H-SOFCs). The generation of 5% A-site deficiency in SrCo0.8Nb0.1Ti0.1O3−δ (S1CNT) could increase the concentration of oxygen vacancies, thus facilitating the ORR kinetics for intermediate and low-temperature solid oxide fuel cells (ILT-SOFCs). The S0.95CNT air electrode delivers excellent area specific resistances (ASRs) at 500 °C, with values of only 0.13 and 1.08 Ω cm2 for S0.95CNT on the Sm0.2Ce0.8O1.9 (SDC) and BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) electrolytes, respectively, and remarkable peak power densities (PPDs) at 600 °C for O-SOFCs and H-SOFCs of 1369 and 569 mW cm–2, respectively, both about 18% higher than that of S1CNT with no deficiency. Overall, this work supplies a simple and effective way to improve the ORR kinetics of S1CNT as the bifunctional air electrode for ILT-SOFCs.

High-Performance and Robust Composite Cathode via W Doping-Induced Phase Separation for Proton Ceramic Fuel Cells

“…The semiconducting behavior converts to the metal-conducting behavior after ∼500 °C. A similar trend of the conducting behavior can be seen in other perovskite-based cathodes . The transition of conductive behavior can be explained by the formation of additional oxygen vacancies after the inflection point temperature.…”

“…When the temperature is below 550 °C, the SCF exhibits a large ASR value, indicating that W doping can lead to ORR activity enhancement, especially at low temperatures. To provide evidence for the reliability of the experiment results, EIS values at 600 °C of all samples are fitted by an equivalent circuit model. ,, In this fitted model, R 1 is related to the resistance from the electrolyte, and R 2 and R 3 represent the resistance of different reaction processes, e.g., charge transfer from the electrolyte to the cathode and the oxygen surface (exchange and diffusion) process, respectively. In addition, CPE1 and CPE2 are constant phase elements.…”

A review of progress in proton ceramic electrochemical cells: material and structural design, coupled with value-added chemical production

“…71 A 5% A-site deficient perovskite of Sr 0.95 Co 0.8 Nb 0.1 Ti 0.1 O 3− δ (S0.95CNT) could increase the concentration of oxygen vacancies. 72 At 600 °C, the S0.95CNT air electrode exhibited an 18% performance improvement over the deficiency-free SCNT counterpart. 72 Moreover, Shi et al demonstrated that the deficiency of 5% Ba in the BaCoO 3 air electrode could improve the protonation ability and reduce the energy barrier in the proton migration process according to first-principles calculations.…”

“…72 At 600 °C, the S0.95CNT air electrode exhibited an 18% performance improvement over the deficiency-free SCNT counterpart. 72 Moreover, Shi et al demonstrated that the deficiency of 5% Ba in the BaCoO 3 air electrode could improve the protonation ability and reduce the energy barrier in the proton migration process according to first-principles calculations. 61 And the surface catalytic activity of O 2 and the chemical stability of the Ba 0.95 CoO 3 compound are also strengthened.…”

“…58 For example, the integrity of the ABO 3 structure could still be preserved even if there is a portion of deficiency in either the A-site or the B-site. The most reported cation deficiencies are within 10%, 59–61 but they could reach up to 27%. 62 The formation of cation deficiencies could introduce additional oxygen vacancies in the perovskite without impairing the original crystal structure.…”