Effects of fabrication parameters on the performance of solid oxide electrolyzer cell

1st International Symposium on Materials for Energy Storage and Conversion (ESC-IS) -- SEP 07-09, 2015 -- Middle E Tech Univ, Ankara, TURKEYWOS: 000378359400002The microstructure has a great impact on the performance of solid oxide fuel/electrolyzer cells while the cell fabrication parameters mainly determine the microstructure of the cell components. In this study, a number of five-layered cells with 16 cm(2) active area are fabricated and the effects of several cell fabrication parameters including sintering temperature and electrode composition on the hydrogen production performance are investigated. The experimental results showed that the optimum sintering temperature of the electrolyte, cathode and anode should be 1400 degrees C, 1250 degrees C and 1075 degrees C, respectively, while the solid weight ratio of both NiO-ScSZ cathode and LSM-ScSZ anode functional layer should be 1:1. The optimized cell produces 38 Sccm H-2 at an operation temperature of 800 degrees C and 1.5 V. Then, the cell size is increased to a commercial size of 81 cm(2) active area. The final cell exhibits an acceptable H-2 production of 154 Sccm H-2 at 800 degrees C and 1.5 V. The relatively lower performance of the commercial-size cell is attributed to the inadequate current distribution/collection due to the increased surface area. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Development of anodes for direct oxidation of methane fuel in solid oxide fuel cells

1st International Symposium on Materials for Energy Storage and Conversion (ESC-IS) -- SEP 07-09, 2015 -- Middle E Tech Univ, Ankara, TURKEYWOS: 000378359400038In addition to pure hydrogen, solid oxide fuel cells (SOFCs) can utilize hydrocarbons as a fuel. However, conventional Ni-based anodes exhibit an excellent catalytic activity towards the hydrocarbon cracking reaction and thus the carbon deposition occurs in the anode. The deposited carbons quickly deactivate the anode irreversibly by covering the active surface of the anode catalyst. As a result, a significant degradation in the cell performance can be seen. In this study, the anode structure is modified by the addition of copper (Cu) and ceria (CeO2) to increase the coking resistance of the cell under direct methane fuel. In this respect, the anodes are infiltrated by different amounts of Cu and CeO2 nitrates via the wet impregnation technique to investigate the effects of Cu and CeO2 loadings on the carbon tolerance of the cell. The effects of the anode porosity and composition are also considered in the study. The carbon resistance thus the service life of the cell with Cu/CeO2/Ni/YSZ anodes is found to be significantly higher than that of conventional Ni-based anodes under direct dry methane fuel. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Mechanical and electrochemical behavior of novel electrolytes based on partially stabilized zirconia for solid oxide fuel cells

WOS: 000355711700069In this study, 3 mol% yttria stabilized zirconia (3YSZ) is investigated as a SOFC electrolyte alternative to 8 mol% yttria stabilized zirconia (8YSZ). The mechanical and electrochemical properties of both materials are compared. The mechanical tests indicate that the thickness of 3YSZ can be reduced to half without sacrificing the strength compared to 8YSZ. By reducing the thickness of 3YSZ from 150 mu m to 75 mu m, the peak power density is shown to increase by around 80%. The performance is further enhanced by around 22% by designing of novel electrode structure with regular cut-off patterns previously optimized. However, the cell with novel designed 3YSZ electrolyte exhibits 30% lower maximum power density than that of the cell with 150 pm-thick standard 8YSZ electrolyte. Nevertheless, the loss in the performance may be tolerated by decreasing the fabrication cost revealing that 3YSZ electrolyte with cut-off patterns can be employed as SOFC electrolyte alternative to 8YSZ. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Effects of ceramic based pastes on electrochemical performance of solid oxide fuel cells

WOS: 000335201800116Various commercially available anode and cathode materials are investigated as the anode and cathode contact paste, respectively, for solid oxide fuel cells. In order to obtain a printable paste, chosen materials are mixed with an organic vehicle and a thinner as well as a pore former. The effect of the contact materials on the cell performance is evaluated experimentally via cell performance measurements by installing a short stack. The pastes are brush painted on the corresponding interconnector and current collecting mesh. A short stack without any contact paste is also tested for comparison as a base case. The impedance and microstructural analyses are also performed through an impedance analyzer and a scanning electron microscope, respectively. The effects of solid loading for two anode and two cathode contact paste materials which provide the best two performances during the electrochemical performance tests are also studied. After optimizing the solid loading in the anode and cathode contact paste according to the performance results, the best contact materials for each side are decided. The final short stack is then installed by using the best combination of contact pastes and then tested. The final cell shows 0.39 W cm(-2) and 0.90 W cm(-2) peak power densities at 700 degrees C and 800 degrees C, respectively, whereas the base cell provides only 0.26 W cm(-2) peak power density at 800 degrees C. The improvement in the cell performance is considered to be due to the enhanced contact and better current collecting by employing contact pastes. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Novel structured gadolinium doped ceria based electrolytes for intermediate temperature solid oxide fuel cells

Novel three-layered intermediate temperature solid oxide fuel cell (SOFC) electrolytes based on gadolinium doped ceria (GDC) are developed to suppress the electronic conductivity of GDC, to improve the mechanical properties of the cell and to minimize power loss due to mixed conductive nature of GDC. Three different electrolytes are fabricated by sandwiching thin YSZ. ScSZ and ScCeSZ between two relatively thick GDC layers. An electrolyte composed of pure GDC is also manufactured for comparison. NiO/GDC and LSCF/GDC electrodes are then coated on the electrolytes by a screen printing route. SEM results show that it is possible to obtain dense and crack free thin layers of YSZ, ScSZ and ScCeSZ between two GDC layers without delamination. Performance measurements indicate that interlayered thin electrolytes act as an electronic conduction barrier and improve open circuit voltages (OCVs) of GDC based cells

A review on cell/stack designs for high performance solid oxide fuel cells

WOS: 000369462100085Besides the general advantages of fuel cells, including clean and quiet operation, solid oxide fuel cells (SOFCs) as being one of the high-temperature fuel cells also provide a relatively high efficiency due to enhanced reaction kinetics at high operating temperatures, The high operation temperature of SOFC also enables internal reforming of most hydrocarbons and can tolerate small quantities of impurities in the fuel. However, a high operation temperature limits the SOFC application areas to stationary applications because of a long start-up period and also is not desirable from the viewpoint of cost reduction and longterm stability especially for the cell materials. Therefore, the lowering the operation temperature of SOFCs is crucial for the cost reduction and the long term operation without degradation as well as the commercialization of the SOFC systems. The reduced operating temperature also helps to reduce the time and to save the energy required for the system start-up enabling SOFCs to have wider application areas including mobile/portable ones. Apart from the low operating temperature, the high performance along with a small volume is another requirement for SOFC to be used in mobile applications. Both can be achieved by fabricating novel SOFCs generating a high power output at low operating temperatures. Therefore, this paper reviews the current status and related research on the development of these high performance-SOFC cell/stack designs. (C) 2015 Elsevier Ltd. All rights reserved

Anode-supported solid oxide fuel cells with ion conductor infiltration

WOS: 000295379300005Nano ion conductor infiltration to anode andcathode side of solid oxide fuel cell (SOFC) significantly improves the performance of an SOFC. The effects of processing parameters such as molar concentration, sintering temperature and holding time are investigated. The performance of fuel cell is evaluated with a test station and an impedance analyzer. The SEM investigation showed that a nano ion conductor phase forms around the main phase in the anode and the cathode. The results showed that nano infiltration enhances significantly the performance of SOFC. The power density is found to increase around two times with infiltration. It is also found that the particle size and the porosity significantly affect the performance of infiltrated SOFC cell. While smaller infiltrated grains enhance the performance lower porosity adversely affects the performance. Copyrightr (C) 2011 John Wiley & Sons, Ltd

Development of high-performance anode supported solid oxide fuel cell

A high performance five-layered anode supported solid oxide fuel cell (SOFC) is developed by low-cost tape casting, co-sintering, and screen printing techniques. The cell is composed of NiO/scandium stabilized zirconia (ScSZ) anode support, NiO/ScSZ anode functional layer (AFL), ScSZ electrolyte, lanthanum strontium ferrite (LSF)/ScSZ cathode functional layer, and LSF cathode current collecting layer. The effects of fabrication parameters on the cell performance are investigated and optimized, including co-sintering temperature, thickness of the anode support, and AFL. The effects of GDC ion conducting phase impregnated into both electrodes also are investigated. The microstructure of the cell is observed using a scanning electron microscope, and the cell performances at various operation temperatures are evaluated by a fuel cell test station. The final cell produces 1.34 W.cm(-2) maximum power density at an operation temperature of 700 degrees C. The high performance is attributed to optimized cell structure as well as increase in the oxide ion conductivity and three-phase boundaries of both anode and cathode layers by nano ion conductor infiltration. Copyright (c) 2011 John Wiley & Sons, Ltd

Glass fiber reinforced sealants for solid oxide fuel cells

Novel sealants for solid oxide fuel cells are developed by addition of glass fiber into glass ceramic as a reinforcement material. Various sealants including three different fiberglass types and four different structural designs are fabricated. The mechanical and sealing performances of the sealants are investigated via tensile and short stack leakage tests, respectively. The tensile tests reveal that the fracture strength of the sealants varies depending on the type and number of the glass fiber used. In general, the sealants having relatively high number of glass fiber layers exhibit relatively low joining strength. The best bonding strength values are obtained from the sealants having a structure where a single glass fiber layer is sandwiched between two glass-ceramic layers. The sealing performance tests are performed for the sealants showing the highest and lowest fracture strengths in the tensile tests as well as for the sealant without glass fiber addition as a base case for a comparison. The results indicate that it is possible to obtain a gas-tight sealing at high temperatures under all pressures studied, whereas leakage occurs at room temperature for all cases considered. However, the sealing performance is found to be related with the mechanical strength of the sealants. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Novel structured electrolytes for solid oxide fuel cells

Novel grate type electrolytes are designed and fabricated to improve the cell performance and to lower the operation temperature of intermediate temperature electrolyte supported solid oxide fuel cells based on scandium and ceria stabilized zirconia by partly reducing the electrolyte thickness. The characteristics of three different small size cells (11.62 cm(2) active area) having various electrolyte designs are investigated. A standard electrolyte supported cell is also produced as a base case for comparison. Performance measurements showed that all cells having grate type electrolyte produce higher power than that of the base cell due to partly reduced electrolyte thickness. Impedance analysis confirmed that the improvement in the performance is due to the decrease in the electrolyte resistance together with the increased number of active sites. Among the three different designs, Cell C showed the highest power output 14.7 W at 800 degrees C corresponding to 1.26 W cm(-2) power density which is more than twice the base case performance