Lanthanum-doped barium stannate, Ba 0.98 La 0.02 SnO 3 (LBS) ceramic oxide was developed as an alternative redox stable anode material for oxide-ion conducting, low-temperature solid oxide fuel cells (350-650 • C). LBS with ZnO as a sintering aid exhibited a high electronic conductivity of 216 S/cm at 650 • C under reducing gas conditions. A flexural strength of ∼66 MPa at 550 • C was obtained for ZnO-doped LBS; further investigation revealed that it can withstand 10 reduction-oxidation and thermal cycles. The performance of ZnO-doped LBS as an anode was determined with a GDC based electrolyte-supported SOFC. The catalytic activity for hydrogen oxidation and oxide conductivity was introduced by infiltration of Ni-GDC precursor. The maximum power densities of 0.28 W/cm 2 (at 0.6 A/cm 2 ) and 0.17 W/cm 2 (at 0.36 A/cm 2 ) was achieved at 650 and 600 • C, respectively, in humidified hydrogen as fuel for 2 wt% ZnO-doped LBS.

Variants of SNNV (Sr 0.2 Na 0.8 Nb 1-x V x O 3 , X=0.1-0.3) ceramic oxides were synthesized via wet chemical method. SNNVs show high electronic conductivity of >100 S/cm when reduced in hydrogen at a relatively low temperature of 650 o C. In particular, 30% V-doped SNNV exhibited the highest conductivity of 300 S/cm at 450 o C. In order to investigate the fuel cell performance, Gd 0.1 Ce 0.9 O 2-δ (GDC) based electrolyte-supported fuel cells were prepared to study the anode characteristics. Sr 0.2 Na 0.8 Nb 0.9 V 0.1 O 3 (SNNV10)-GDC composite was used as an anode and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF)-GDC as a cathode. Both electrodes were porous and sintered at 1050 o C for 2 h in air. The anode side of the fuel cell was infiltrated with 10 wt.% GDC/Ni-GDC precursor to activate the anode for fueloxidation. I-V characteristics were determined in gas conditions such as dry/humidified hydrogen and methane at 650 o C. With the infiltration Ni-GDC, peak power density (PPD) of 280 mW/cm 2 and 220 mW/cm 2 in dry H 2 and CH 4 , respectively, were obtained at 650 o C, which is higher than GDC alone as infiltrate. The high resistances in the humidified conditions are attributed to the lower conductivity of SNNV10 in high P O2 atmospheres.

While there have been significant breakthroughs in new functional cathodes facilitating the oxygen reduction reaction (ORR) for low-temperature solid oxide fuel cells (LT-SOFCs), sluggish oxygen charge transfer across the cathode/electrolyte heterogeneous interface also hinders overall performance. To promote oxygen ion exchange at the interface, a thin layer of cerium oxide decorated by an amorphous cobalt oxide overcoating was introduced to function as a fast oxygen ion transport pathway at the interface. The peak power density (PPD) of the modified cell achieved 767 mW/cm 2 at a low operation temperature of 550 °C, which is almost 3 times the power output of the unmodified cell. Oxygen isotope exchange confirmed that the oxygen reduction active cobalt oxide nanolayer drastically reduced the energy barrier for oxygen transport across the solid−solid interface. Such interface modification successfully demonstrates an effective route to enable fast ORR and oxygen transport across the cathode/electrolyte interface at low temperature.

A critical factor hampering the deployment of fuel-flexible, low-temperature solid oxide fuel cells (LT-SOFCs) is the long-term stability of the electrode in different gas environments. Specifically, for state-of-the-art Ni-cermet anodes, reduction/oxidation (redox) cycles during fuel-rich and fuel-starved conditions cause a huge volume change, eventually leading to cell failure. Here, we report a robust redox-stable SrFe0.2Co0.4Mo0.4O3 (SFCM)/Ce0.9Gd0.1O2 ceramic anode-supported LT-SOFC with high performance and remarkable redox stability. The anode-supported configuration tackles the high ohmic loss associated with conventional ceramic anodes, achieving a high open circuit voltage of ∼0.9 V and a peak power density of 500 mW/cm2 at 600 °C in hydrogen. In addition, ceramic anode-supported SOFCs are stable over tens of redox cycles under harsh operating conditions. Our study reveals that oxygen nonstoichiometry of SFCM compensates for the dimensional changes that occur during redox cycles. Our results demonstrate the potential of all ceramic cells for the next generation of LT-SOFCs.

Exploitation of alternative anode materials for low-temperature solid oxide fuel cells (LT-SOFCs, 350–650 °C) is technologically important but remains a major challenge. Here we report a potential ceramic anode Y0.7Ca0.3Cr1–x Cu x O3−δ (x = 0, 0.05, 0.12, and 0.20) (YCC) exhibiting relatively high conductivity at low temperatures (≤650 °C) in both fuel and oxidant gas conditions. Additionally, the newly developed composition (YCC12) is structurally stable in reducing and oxidizing gas conditions, indicating its suitability for SOFC anodes. The I–V characteristics and performance of the ceramic anode infiltrated with Ni-(Ce0.9Gd0.1O2−δ)­(GDC) were determined using GDC/(La0.6Sr0.4CoO3‑δ)­(LSC)-based cathode supported SOFCs. High peak power densities of ∼1.2 W/cm2 (2.2A/cm2), 1 W/cm2 (2.0A/cm2), and 0.6 W/cm2 (1.3 A/cm2) were obtained at 600, 550, and 500 °C, respectively, in H2/3% H2O as fuel and air as oxidant. SOFCs showed excellent stability with a low degradation rate of 0.015 V kh–1 under 0.2 A/cm2. YCC-based ceramic anodes are therefore critical for the advancement of LT-SOFC technology.

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The development of alternative ceramic anodes for low-temperature solid oxide fuel cells (LT-SOFCs) is essential to overcome the inherent challenges such as redox instability and coking associated with Ni-based cermet anodes. Moreover, due to the large electrolyte ohmic loss at low temperature, it is critical to developing an electrode supported cell that allows electrolyte thickness reduction. Here we successfully demonstrated a high performance SrFe0.2Co0.4Mo0.4O3−δ (SFCM) ceramic anode supported LT-SOFC with a peak power density of 730 mW cm−2 and 300 mW cm−2 at ambitious low temperatures of 550 °C and 450 °C, respectively, in humidified H2. The new anode material SFCM exhibits exceptional conductivity of over 30 S cm−1 at 450 °C in humidified H2, providing essential current collection capability as an anode backbone appropriate for the infiltration of Ni-gadolinia doped ceria (GDC) electrocatalysts. Compared to conventional Ni-cermet anodes, the nano-sized Ni-GDC particles in our SFCM based electrode significantly improves the cell stability in hydrocarbon gases. We demonstrated a stable long-term operation over a period of 380 h in CH4–containing gas mixtures at 450 °C with a voltage degradation rate of 4% per 1000 h at a constant current of 0.2 A*cm−2. Our results demonstrate a high performance ceramic anode with high stability for low temperature operation.

Fuel flexibility is a unique feature of solid oxide fuel cells (SOFCs), the instability of Ni-based cermet anodes in hydrocarbon fuels impede the advancement of low-temperature solid oxide fuel cells (LT-SOFCs). Here we demonstrate highly stable LT-SOFCs prepared by catalytically modifying the surface of a conductive ceramic oxide, SrFe 0.2 Co 0.4 Mo 0.4 O 3 (SFCM), using Ni-GDC nanoparticles (<100 nm). The nano-sized Ni-GDC electrocatalysts, resulting from careful optimization of Ni-to-GDC ratio, and subsequent low-temperature calcination process, enhance the fuel oxidation kinetics and stability of SFCM anode significantly. An optimized Ni-to-GDC ratio of 1:10 on SFCM-supported SOFC delivered peak power density of 0.75, 0.65 and 0.36 W cm −2 at 650 °C, 600 °C and 550 °C, respectively, in humidified H 2 and 0.62, 0.39 and 0.22 W cm −2 at 650 °C, 600 °C and 550 °C, respectively, in CH 4 /H 2 gas mixtures, nearly 4× higher than GDC as electrocatalyst. Remarkably, for the same Ni-to-GDC ratio, a stable cell voltage of 0.82 V is maintained over 200 h of operations (under current) at 600 °C in CH 4 /H 2 gas mixtures.