Chamber Solid Oxide Fuel Cell Research Articles

Single chamber Solid Oxide Fuel Cells selective electrodes: A real chance with brownmillerite-based nanocomposites

In this contribution brownmillerite-based nanocomposite cathode for Single-Chamber Solid Oxide Fuel Cells is developed. These cells can be very attractive especially for small and cheap devices because of the absence of seals. The efficiency of SC-SOFCs is strictly connected to the selectivity of anode and cathode, the bottleneck for this technology. The development of a cathode inert in fuel oxidation is particularly challenging. Our strategy is to start from a catalytically un-active support (CFA = Ca2FeAl0.95Mg0.05O5) and induce the formation of iron oxide based nanoparticles, expected to activate oxygen. Symmetric (CFA + FeOx/CGO/CFA + FeOx) and complete cells (CFA + FeOx/CGO/Ni-CGO) are studied in air and methane/oxygen 2:1 mixture. The Area Specific Resistance of CFA + FeOx is less than 1/3 that of CFA. The high selectivity allows to reach an efficiency of 25%; power still needs to be increased but we demonstrated the possibility to develop selective low cost electrodes. The effect of air, methane/oxygen exposure and the heat treatments were carefully investigated.

Fabrication and evaluation of a novel wavy Single Chamber Solid Oxide Fuel Cell via in-situ monitoring of curvature evolution

Wavy type Single Chamber Solid Oxide Fuel Cells (SC-SOFCs) are beneficial for improved triple phase boundary conditions contributing to higher performance, compared with planar type SC-SOFCs of the same diameter. This study presents a fabrication process for wavy-type, cathode-supported SC-SOFCs with a single fabrication step via co-sintering of a triple-layer structure consisting of NiO/CGO-CGO-LSCF, with a thickness ratio of 1:3:9 respectively. Curvature evolution occurs due to different sintering behaviour of each layer during the co-sintering process. In-situ observation of each layer during the co-sintering process allows for minimisation of mismatched stresses to avoid unnecessary warping and cracking. Bilayers, consisting of NiO/CGO-CGO and CGO-LSCF, are co-sintered at 1200°C. In-situ observation, to monitor the shrinkage of each material and the curvature evolution of the structures, is performed using a long focus microscope (Infinity K-2). Monitoring curvature behaviour in real time minimised the development of undesired curvature in the triple-layer structure. Performance testing of wavy cell is carried out in a methane-air mixture (CH4:O2=1:1). The wavy SC-SOFC generated 0.39V and 9.7mWcm−2 at 600°C, which produced 260% and 540% increments in OCV and in maximum power density, respectively, over the planar SC-SOFC under the same operational conditions.

Fabrication of Micro Single Chamber Solid Oxide Fuel Cell Using Photolithography and Pulsed Laser Deposition

This paper focuses on the fabrication of micro-coplanar interdigitated single chamber solid oxide fuel cell (μ-SC-SOFC) using a combination of micropatterning technique and thin-film deposition technology. Photolithography was used to generate the micro-interdigitated photoresist patterns on the substrates. Pulsed laser deposition (PLD) method was used to deposit thin films of microstructured electrolytes yttrium stabilized zirconia (YSZ) and electrodes (anode: YSZ + NiO and cathode: lanthanum strontium ferrous cobalt (LSCF)). Process parameters were optimized to obtain consistent functional microstructure and crystal morphology. This research shows good potential for combinatorial manufacturing methods to fabricate high quality and repeatable micro fuel cell components.

Flame-assisted fuel cells running methane

In this study, the flame-assisted fuel cell (FFC1) was investigated by using methane/air flames. The confrontation between FFC temperature and fuel concentration at various conditions was investigated which uncovered the complex behavior of FFCs performance. Variations in fuel/air equivalence ratio, fuel flow rate and distance between FFC and burner outlet were studied. A critical distance for FFC placement above the burner outlet was uncovered, which has a significant impact on FFC performance. A high power density of 791 mW cm−2 was achieved which is comparable to the dual chamber solid oxide fuel cell (SOFC) and single chamber SOFC. The short-term test exhibited good stability of the FFCs under operation despite the presence of carbon formation on the anode surface.

BaLaIn2O5.5 Electrolyte Single Chamber Solid Oxide Fuel Cells with Novel Porous Electrolyte Surface Structure

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CHARACTERISTICS OF BSCF5582 POWDER AND FUEL CELL PERFORMANCE UNDER SINGLE CHAMBER CONDITIONS EVALUATION

The Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF5582) powder is synthesized as the cathode material for Single Chamber Solid Oxide Fuel Cell (SC-SOFC) La1.8Dy0.2Mo2O9 (LDM) based electrolyte. The crystal size, which was calculated from the XRD result, is around 48.59 nm by taken the (110) plane. The morphology of cell cross-section is good adhesion without any reaction between layers. The single cell NiO+GDC/LDM/i-GDC/GDC-BSCF5582 consisting 26 μm-thick cathode generates peak power density of 200 mW/cm2 at 650 oC under flowing mixture of CH4/air in temperature range of 575-675 oC. The BSCF5582 can be used for SC-SOFC using LDM electrolyte under single chamber conditions.

Fabrication of High Performance BaLaIn2O5.5 Electrolyte Single Chamber Solid Oxide Fuel Cell by Using Sublimation Materials as Pore Former in Electrode Preparation

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Investigations on Single Chamber Solid Oxide Fuel Cells: From Single Cell to Micro-Stack

In this paper, some investigation results of our research group about single chamber solid oxide fuel cells including single cells and micro-stacks are presented. On single cell investigations, both electrolyte-supported (ES) and anode- supported (AS) membrane ones were studied. The primary work focused on reducing the inner resistance, improving the open circuit voltage (OCV) as well as power density, and enhancing the operation stability. On 2-cell short stacks, our investigation focused on AS type stacks with different configurations and the structure parameter effect. To develop useful SC-SOFC system, more stack configurations have been designed and tested. Many efforts have been made to optimize the gas flow field of multi-cell micro-stacks in order to enhance the OCV, power output and fuel utilization. Configurations of SC-SOFC stacks, including star-type, array type and micro-stack with root gas tubes have been designed and tested successfully.

Numerical Approach of a Single-Chamber Solid Oxide Fuel Cell without Mixed Reactant Feeding

Satisfactory power densities for Single Chamber Solid Oxide Fuel Cells (SC-SOFC) can be obtained with ceramic materials already used in dual chambers SOFC. In order to increase the oxygen access trough the cathode, the authors propose to combine a SC-SOFC and a dual chamber SOFC by using a porous ceramic membrane. In this computing work, species transport is governed by convection-diffusion equations in the gas channel and the porous media. In addition, momentum balances are solved using Brinkman formulation through the porous cell. Charge transfer occurs at the electrode/electrolyte interface and is described by the general Butler-Volmer equation. Simulations allow the calculation of the distributions of partial pressures for all the gas species within the cell (CH4, H2, CO, CO2, H2O, O2, N2). As expected, the injection of only 3% of the steam water increases the chemical conversion of methane.

Investigations on Single Chamber Solid Oxide Fuel Cells: From Single Cell to Micro-Stack

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Development of Single Chamber Solid Oxide Fuel Cells (SCFC)

AbstractSingle Chamber Solid Oxide Fuel Cells (SCFC) have been prepared using an electrolyte as support (Ce0.9Gd0.1O1.95 named GDC). Anode (Ni‐GDC) and different cathodes (Sm0.5Sr0.5CoO3 (SSC), Ba0.5Sr0.5Co0.2Fe0.8O3 (BSCF) and La0.8Sr0.2MnO3 (LSM)) were placed on the same side of the electrolyte. All the electrodes were deposited using screen‐printing technology. A gold collector was also deposited on the cathode to decrease the over‐potential. The different materials and fuel cell devices were tested under propane/air mixture, after a preliminary treatment under hydrogen to reduce the as‐deposited nickel oxide anode. The results show that SSC and BSCF cathodes are not stable in these conditions, leading to a very low open circuit voltage (OCV) of 150 mV. Although LSM material is not the more adequate cathode regarding its high catalytic activity towards hydrocarbon conversion, it has a better chemical stability than SSC and BSCF. Ni‐GDC‐LSM SCFC devices were elaborated and tested; an OCV of nearly 750 mV could be obtained with maximum power densities around 20 mW cm–2 at 620 °C, under air–propane mixture with C3H8/O2 ratio equal to 0.53.

Nickel Based Anodes of Single Chamber Solid Oxide Fuel Cells: A Catalytic Study

Single chamber solid oxide fuel cells (SCFC) are an alternative concept to traditional SOFC's. Conventional anodes, which consist of a cermet of metallic Ni and ionic conductor, have to work under a mixture of hydrocarbon and oxygen. This paper presents a catalytic study of C3H8 oxidation by Ce0.9Gd0.1O1.95 and nickel. The influence of temperature and oxygen to propane ratio on the nickel oxidation state are clarified thanks to catalytic tests and electrical conductivity measurements. The results show that the temperature must be higher than a critical value in order to maintain the nickel particles in the metallic state. Furthermore, at high temperature, the conversion of the initial mixture leads to the water-gas-shift equilibrium.

Single Chamber Solid Oxide Fuel Cells (SC-SOFCs) based on a Proton Conducting Electrolyte

Single chamber solid oxide fuel cells (SC-SOFCs) are promising for portable power applications because they are simpler than the conventional dual-chamber cells. SC-SOFCs based on the cell Ni/BaCe0.3Zr0.5Y0.2O3-δ (BCZY)/Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) were investigated under gas mixtures of propane (C3H8), oxygen (O2), and helium (He) with different compositions. To enhance the fuel partial oxidation at low temperatures, a porous layer of Ru was added onto the anode surface. Two configurations, finger (with parallel electrodes) and sandwich (with electrodes on opposite sides of the pellets), were analyzed

Study on Electrolyte-Supported Single Chamber Solid Oxide Fuel Cell Stack

Single cell and short stacks supported with electrolyte were prepared and operated under single chamber solid oxide fuel cell (SC-SOFC) condition. The single cell was tested to investigate the ratio of fuel and oxygen in the mixture working gas as well as the operating temperature. Then single electrolyte pellet-supported SC-SOFC stacks with 2 or 3 cells were fabricated and tested. A 2-cell stack could provide an the open circuit voltages (OCV) of 1.66V that was lower than the OCV sum of near 2V for two standing alone SC-SOFC for some addition cells might composed between each possible pair of anode and cathode on the same bulk electrolyte and depressed the OCV of stack. The OCVs of a 3-cell stack were 2.758V and 2.501V, and the maximum power (MP) were 20.76mW and 16.02mW, at 700 oC and 750 oC respectively.

Study on Electrolyte-Supported Single Chamber Solid Oxide Fuel Cell Stack

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Single Chamber Solid Oxide Fuel Cells (SC-SOFCs) based on a Proton Conducting Electrolyte

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Nickel Based Anodes of Single Chamber Solid Oxide Fuel Cells: A Catalytic Study

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Modelling of Gas Flow and Electrochemical Effects in a Single Chamber-Solid Oxide Fuel Cell (SC-SOFC)

A comparison of the gas flow distribution and reactant utilization in a single chamber solid oxide fuel cell (SCSOFC) between the parallel and perpendicular cell configuration (with respect to the gas flow direction) has been discussed in detail. An electrochemical-fluid coupled numerical model in a five layer membrane electrode assembly (MEA) is developed. The model accounts for the major transports of convective and diffusive mass transfer, electrode kinetics, and potential fields. The results show gas flow and electrochemical effects inside the cell in each configuration and suggest that the parallel design provides better gas flow than perpendicular configuration. A uniform reactant utilization is observed in case of perpendicular design as compared to the parallel configuration. In order to take advantage of both the gas flow and electrochemical performance of the cell, use of a fully porous cell (including porosity of the electrolyte) is suggested in perpendicular configuration. The model can predict the effect of gas flow/ electrochemical performance, especially in situations where several cells are placed at different distances in the duct. The model is solved using COMSOL Multiphysics 3.3a, a commercial finite element analysis (FEM) software package.

Development of Single Chamber Solid Oxide Fuel Cell using BaLaIn2O5.5 (BLI) Solid Electrolyte: Introduction of Sublimation Materials as Pore Former in Electrode Preparation

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Modelling of Gas Flow and Electrochemical Effects in a Single Chamber-Solid Oxide Fuel Cell (SC-SOFC).

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