Solid Oxide Fuel Cell Running Research Articles

Characterization of the Ni-ScSZ anode with a LSCM–CeO 2 catalyst layer in thin film solid oxide fuel cell running on ethanol fuel

Solid oxide fuel cell (SOFC) running directly on hydrocarbon fuels has attracted much attention in recent years. In this paper, a dual-layer structure anode running on ethanol is fabricated by tape casting and screen-printing method, the addition of a LSCM–CeO 2 catalyst layer to the supported anode surface yields better performance in ethanol fuel. The effect that the synthesis conditions of the catalyst layer have on the performances of the composite anodes is investigated. Single cells with this anode are also fabricated, of which the maximum power density reaches 669 mW cm −2 at 850 °C running on ethanol steam. No significant degradation in performance has been observed after 216 h of cell testing when the Ni-ScSZ13 anode is exposed to ethanol steam at 700 °C. Very little carbon is detected on the anode, suggesting that carbon deposition is limited during cell operation. Consequently, the LSCM–CeO 2 catalyst layer on the surface of the supported anode makes it possible to have good stability for long-term operation in ethanol fuel due to low carbon deposition.

Performance of Ce/Fe oxide anodes for SOFC operating on methane fuel

The performance of Ce 1− x Fe x O 2− δ ( x = 0.1, 0.2) was studied as anode for solid oxide fuel cell running on methane in this paper. The oxides were prepared by the citrate method. The polarization resistance of electrode was measured in the two-electrode symmetric cell configuration and an electrolyte-supported cell was prepared to assess Ce 0.8Fe 0.2O 2− δ anode performance of running on methane fuel. The results suggested that Ce 0.8Fe 0.2O 2− δ has a significant effect on the electrochemical oxidation of methane. A maximum power density of single cell was 52 mW/cm 2 at 800 °C and little carbon deposition was shown on the anode operating in humidified methane for 20 h. Therefore, Ce 0.8Fe 0.2O 2− δ is a promising candidate for anode of solid oxide fuel cell running on methane fuel, which breaks a new path to solve the problem of carbon deposition in methane.

Importance of pressure gradient in solid oxide fuel cell electrodes for modeling study

The pressure gradients in the electrodes of a solid oxide fuel cell (SOFC) are frequently neglected without any justification in calculating the concentration overpotentials of the SOFC electrodes in modeling studies. In this short communication, a comparative study has been conducted to study the effect of pressure gradients on mass transfer and the resulting concentration overpotentials of an SOFC running on methane (CH 4) fuel. It is found that the pressure gradients in both anode and cathode are significant in the fuel cell electrochemical activities. Neglecting the anode pressure gradient in the calculation can lead to underestimation of the concentration overpotential by about 20% at a typical current density of 5000 A m −2 and at a temperature of 1073 K. The deviation can be even larger at a higher temperature. At the cathode, neglecting the pressure gradient can result in overestimation of the concentration overpotential by about 10% under typical working conditions.

Performance of Ni/ScSZ cermet anode modified by coating with Gd 0.2Ce 0.8O 2 for an SOFC running on methane fuel

A Ni/scandia-stabilized zirconia (ScSZ) cermet anode was modified by coating with nano-sized gadolinium-doped ceria (GDC, Gd 0.2Ce 0.8O 2) prepared using a simple combustion process within the pores of the anode for a solid oxide fuel cell (SOFC) running on methane fuel. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed in the anode characterizations. Then, the short-term stability for the cells with the Ni/ScSZ and 2.0 wt.%GDC-coated Ni/ScSZ anodes in 97%CH 4/3%H 2O at 700 °C was checked over a relative long period of operation. Open circuit voltages (OCVs) increased from 1.098 to 1.179 V, and power densities increased from 224 to 848 mW cm −2, as the operating temperature of an SOFC with 2.0 wt.%GDC-coated Ni/ScSZ anode was increased from 700 to 850 °C in humidified methane. The coating of nano-sized Gd 0.2Ce 0.8O 2 particle within the pores of the porous Ni/ScSZ anode significantly improved the performance of anode supported cells. Electrochemical impedance spectra (EIS) illustrated that the cell with Ni/ScSZ anode exhibited far greater impedances than the cell with 2.0 wt.%GDC-coated Ni/ScSZ anode. Introduction of nano-sized GDC particles into the pores of porous Ni/ScSZ anode will result in a substantial increase in the ionic conductivity of the anode and increase the triple phase boundary region expanding the number of sites available for electrochemical activity. No significant degradation in performance has been observed after 84 h of cell testing when 2.0 wt.%GDC-coated Ni/ScSZ anode was exposed to 97%CH 4/3%H 2O at 700 °C. Very little carbon was detected on the anodes, suggesting that carbon deposition was limited during cell operation. Consequently, the GDC coating on the pores of anode made it possible to have good stability for long-term operation due to low carbon deposition.

A Solid Oxide Fuel Cell Running on H[sub 2]S∕CH[sub 4] Fuel Mixtures

Solid oxide fuel cells (SOFCs) that were capable of running on sour natural gas were fabricated and tested. The electrolyte of the SOFCs was yttria-stabilized zirconia (YSZ), the anode material was a strontium-doped lanthanum vanadate with a nominal composition of La 0 . 7 Sr 0 . 3 VO 3 (LSV), and the cathode was a porous composite of La 0 . 8 5 Sr 0 . 1 5 MnO 3 (LSM) and YSZ. The observed peak power density at 950°C was 280 mW/cm 2 when 5% H 2 S/95% CH 4 gas mixture was used as the fuel and ambient air as the oxidant. Analysis of the effluent gas from the SOFC indicated that, apart from being oxidized electrochemically to sulfur and SO 2 , a significant portion of the H 2 S was transformed to carbon disulfide (CS 2 ), an important solvent currently used to dissolve heavy hydrocarbon deposits. The results indicated that SOFCs with a LSV anode might be used for the processing of sour natural gas (containing CH 4 , H 2 S, etc.) in which both electricity and high value chemicals (i.e., sulfur and CS 2 ) are produced simultaneously.

Improvement of anode performance by surface modification for solid oxide fuel cell running on hydrocarbon fuel

Abstract A Ni/ yttria-stabilized zirconia (YSZ) cermet anode was modified by coating with samaria-doped ceria (SDC, Sm0.2Ce0.8O2) sol within the pores of the anode for a solid oxide fuel cell (SOFC) running on hydrocarbon fuel. The surface modification of Ni/YSZ anode resulted in an increase of structural stability and enlargement of the triple phase boundary (TPB), which can serve as a catalytic reaction site for oxidation of carbon or carbon monoxide. Consequently, the SDC coating on the pores of anode made it possible to have good stability for long-term operation due to low carbon deposition and nickel sintering. The maximum power density of an anode-supported cell (electrolyte; 8 mol% YSZ and thickness of 30 μm, and cathode; La0.85Sr0.15MnO3) with the modified anode was about 0.3 W/cm2 at 700 °C in the mixture of methane (25%) and air (75%) as the fuel and air as the oxidant. The cell was operated for 500 h without significant degradation of cell performance.

First Steps of a Cell Model Centered on the Direct Internal Reforming at the Anode

Solid oxide fuel cell (SOFC) optimization requires detailed analysis based on both, experimental and simulated data, in the first part of this work, a review of anode models is presented. The various approaches, the considered parameters and the calculated data are analyzed. In the second part, a computer program model of a SOFC running with methane steam reforming within the anode is presented, based on a kinetic approach. First results are given and discussed.

Electrocatalytic activity of a Gd2Ti0.6Mo1.2Sc0.2O7-δ anode towards hydrogen and methane electro-oxidation in a solid oxide fuel cell

Mixed conducting oxide anodes are being considered for the direct utilisation of natural gas in high temperature fuel cells. This work refers to the electrochemical characterization of the pyrochlore Gd2Ti0.6Mo1.2Sc0.2O7-δ (GTMS) as anode in a solid oxide fuel cell running in low humidity hydrogen or methane.