Structural Properties of Anode Composites Precursor of A Solid Oxide Fuel Cell Prepared Via Combustion Synthesis Route (original) (raw)
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International Journal of Innovative Research in Science, Engineering and Technology, 2014
A precursor to SOFC anode was made via solution combustion technique that is NiO-GDC (Gadolinia doped Ceria) composites by mixing nitrates of cerium, gadolinium and nickel in stoichiometric ratio of composition to form the final precursor product as Ce0.90Gd0.10O1.95 - 0.40 NiO. The fuel for the combustion synthesis that is glycine’s concentration was varied between 0.5 mole% to 1.4 mole%. The temperature of the resultant sintered pellets was varied between 30 to 800oC and electrical properties of the NiO-CGO composite was studied by means of admittance plots between conductivity & susceptance. The results showed that the composite precursor varied in conductivity and activation energy depending on the concentration of the fuel.
TPR studies on NiO-CGO composites prepared by combustion synthesis
Ceramics International, 2014
NiO-ceria composites, which are promising candidates as anodes for intermediate temperature solid oxide fuel cells (IT-SOFCs) were prepared by urea combustion synthesis (UCS) method. The UCS method is, in general, a highly suitable synthesis method for the production, at low temperatures, of fine and reactive powders. By means of XRD and SEM-EDX techniques, the structural, microstructural and compositional behavior of the as-prepared powders has been studied. In addition, temperature programmed reduction (TPR) tests were performed to investigate the reducibility of the composites. After reduction of the NiO-CGO as-prepared compositions, the combustion powders exhibit the presence of Ni, the fluorite CGO solid solution that remains stable and NiO is no longer present. The morphology and size of the nanoparticles and aggregates of the as-prepared powders make them reactive at intermediate temperatures (400-800 1C). TPR tests show wide overlapping peaks which are associated with the two primary reduction stages; one is related to the surface NiO reduction mechanism and the other to the coexistence of interactions between the NiO-CGO surface and bulk reduction processes. Further, after TPR measurements the resulting products have high phase stability and reproducibility.
2021
Low Temperature Solid oxide fuel cells (LTSOFCs) are considered as one of the futuristic electrochemical energy delivering devices because of their good conversion efficiency and eco-friendly technology. To improve the efficiency of SOFC further, research activities are being carried-out across the globe to reduce the operating temperature from 1273 K to around 873 K. For low temperature operation of SOFC, conventional anode such as Ni-YSZ is not suitable because of low ionic conductivity of YSZ. In this research, a set of anode materials, such as, as NiO–Ce0.9Gd0.1O2-δ, NiO– Ce0.8Gd0.2O2-δ, NiO–Ce0.9Sm0.1O2-δ and NiO – Ce0.8Sm0.2O2-δ were prepared by simple soft chemical precipitation method for application in LTSOFC. The prepared materials were nano-structured, porous and highly homogeneous. The phase constituents, spectral characteristics, particle properties, elements analysis and microstructure of the samples were studied by XRD, FTIR, particle size analysis, EDAX and SEM techn...
Hydrogen, Fuel Cell & Energy Storage, 2022
In this study, nickel oxide-gadolinium doped ceria, NiO-GDC, composite powder was synthesized by the sol-gel method with a new Ni(II) complex. A new Ni(II) complex, chemical formula [Ni(μ-L)] n (NO 3) 2 , L = N'-(pyridine-2-yl)methylene) isonicotinohydrazide), was used as a new precursor. The new Ni(II) complex was prepared by a reaction between ligand, L, and Ni(NO 3).6H 2 O using the hydrothermal method. Then the NiO-GDC powders were synthesized using Ce(NO 3) 3 .6H 2 O, and Gd(NO 3) 3 .6H 2 O, and the as-synthesized new Ni(II) complex [Ni(μ-L)] n (NO 3) 2 with the sol-gel method. The NiO-GDC powder was modified to increase the performance of solid oxide fuel cells (SOFCs) operating at intermediate temperatures (600-800 ℃) by increasing the three-phase boundary region in the anode. Finally, the NiO-GDC anode powders prepared with the new precursor were compared with the NiO-GDC anode powders synthesized from metal nitrates as a precursor. The results showed that the modified NiO-GDC anode had more three-phase boundaries, TPB, a more uniform microstructure, a higher specific surface area, and a porous structure that effectively improved the electrochemical performance of the electrode. SOFC half-cell resistance with this high-performance anode decreased by 85 % at 800 ℃ compared to conventional half-cells.
international journal for research in applied science and engineering technology ijraset, 2020
In the present research work, for solid oxide fuel cell, nano composite anode materials were synthesized using nickel oxide and gadolinium doped ceria (GDC20) and. Anode materials prepared for low temperature operating solid oxide fuel cells, from metallic NiO and ceramic GDC20 powders. These are mechanically mixed as X (NiO) +1-X (Ce 0.8 Gd 0.2 O 2-δ) where (X = 30, 40 ,45,50,55,60 wt. %). The mixed powders were ground and pelletized with respect to X. All the samples were characterized after sintered at the temperature 1300 o C. Systematically studied the structure, purity, phase and structural parameters of as-synthesized NiO-GDC20 anode samples were carried out by XRD and SEM. Electrical characterizations such as A.C Conductivities and D.C conductivities were carried out using impedance spectroscopy and four probe D.C conductivity measurements respectively. The activation energies of the anode samples were estimated from 300-500 o C. The activation energies of A.C conductivities are observed that decrease with increase in frequencies.
NiO–CGO in situ nanocomposite attainment: One step synthesis
The CeO2-based electrolyte low temperature SOFCs require special electrodes with a higher performance and compatibility. The performance of the CeO2-based composite anodes depends on microstructural features such as particle size, tripe phase boundaries (TPB), surface area, and percolation. Some of the primary parameter can be manipulated during the materials synthesis. In this work the compound NiO–Ce0.9Gd0.1O1.95 (NiO–CGO), used as anode in SOFC, was synthesized by two different processes. Both of them are based on the polymeric precursor method. Characterized by simultaneous thermogravimetry-differential thermal analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and dilatometry. The refinement of the XRD data indicated that the composite sample synthesized by the process called “one step synthesis” produced smaller crystallite size in comparison to the sample attained by the two steps process. Simple preliminary performance tests were done with single cells in which such I–V curves indicated that the cell with one step anode had better performance. “One step synthesis” product, in situ nanocomposite, presented similar fine grained particle sizes for both phases Ni and CGO, which would be beneficial to the electrochemical activity, also indicated by first performance tests.
A versatile route for the preparation of Ni–CGO cermets from nanocomposite powders
A comparative microstructural study between Ni-Ce 0.9 Gd 0.1 O 1.95 (Ni-CGO) anodes obtained from NiO-CGO nanocomposite powders prepared by in situ one-step synthesis and by mechanical mixture (two-step synthesis) of NiO and CGO powders is reported. The open porosity and microstructure of sintered and reduced pellets were investigated as a function of the citric acid content used as pore forming agent. Nanosized crystallites for the one-step and two-step routes were around 18 nm and 24 nm against 16 nm and 37 nm, for CGO and NiO, respectively. Overall results show that both routes provided suitable microstructures either for anode-support, or for functional anodes for solid oxide fuel cells (SOFCs), with more versatile characteristics in the case of the one-step route. The electrical characterization of selected NiO-CGO samples, carried out between 90 and 260 1C by impedance spectroscopy, confirms electrical percolation of both phases in the composites. However, based on combined microstructural and impedance data, it seems clear that the one-step processing route is the best approach to make SOFC anodes with improved performance.
International Journal of Hydrogen Energy, 2013
Low temperature solid oxide fuel cell Transition metal oxides Ceria-carbonate composite electrolyte Lithiated NiO a b s t r a c t In this work, the effect of copper, iron and cobalt oxides on electrochemical properties of lithiated NiO cathodes was reported in low temperature solid oxide fuel cell (LT-SOFC) with ceria-carbonate composite electrolyte. The modified lithiated NiO cathodes were characterized by XRD, DC conductivity, SEM and electrochemical measurements. In spite of lower conductivities of modified cathodes, LieNieM (M ¼ Cu, Fe, Co) oxides with the order of LieNieCo oxide > LieNieFe oxide > LieNieCu oxide, compared with that without modification, the catalytic activities of all the LieNieM oxides were improved. In particularly, cobalt oxide modification favors both charge transfer and gas diffusion for O 2 reduction reaction as confirmed by AC impedance measurements. SEM micrographs show that grains aggregate with the modification of copper oxide or iron oxide, which may be responsible for the increased gas diffusion resistance. The results indicate that the lithiated NiO modified by cobalt oxide as cathode is an alternative to improve LT-SOFC performance with ceria-carbonate composite electrolyte.
Solid oxide fuel cell bi-layer anode with gadolinia-doped ceria for utilization of solid carbon fuel
Journal of Power Sources, 2010
Pyrolytic carbon was used as fuel in a solid oxide fuel cell (SOFC) with a yttria-stabilized zirconia (YSZ) electrolyte and a bi-layer anode composed of nickel oxide gadolinia-doped ceria (NiO-GDC) and NiO-YSZ. The common problems of bulk shrinkage and emergent porosity in the YSZ layer adjacent to the GDC/YSZ interface were avoided by using an interlayer of porous NiO-YSZ as a buffer anode layer between the electrolyte and the NiO-GDC primary anode. Cells were fabricated from commercially available component powders so that unconventional production methods suggested in the literature were avoided, that is, the necessity of glycine-nitrate combustion synthesis, specialty multicomponent oxide powders, sputtering, or chemical vapor deposition. The easily-fabricated cell was successfully utilized with hydrogen and propane fuels as well as carbon deposited on the anode during the cyclic operation with the propane. A cell of similar construction could be used in the exhaust stream of a diesel engine to capture and utilize soot for secondary power generation and decreased particulate pollution without the need for filter regeneration.
Synthesize and characterization of nanocomposite anodes for low temperature solid oxide fuel cell
International Journal of Hydrogen Energy, 2015
Solid oxide fuel cells have much capability to become an economical alternative energy conversion technology having appropriate materials that can be operated at comparatively low temperature in the range of 400-600 o C. The nano-scale engineering has been incorporated to improve the catalytic activity of anode materials for solid oxide fuel cells. Nanostructured Al 0.10 Ni x Zn 0.90-xO oxides were prepared by solid state reaction, which were then mixed with the prepared Gadolinium doped Ceria GDC electrolyte. The crystal structure and surface morphology were characterized by XRD and SEM. The particle size was evaluated by XRD data and found in the range of 20-50 nm, which was then ensured by SEM pictures. The pellets of 13mm diameter were pressed by dry press technique and electrical conductivities (DC and AC) were determined by four probe techniques and the values have been found to be 10.84 and 4.88 S/cm, respectively at hydrogen atmosphere in the temperature range of 300-600 o C. The Electrochemical Impedance Spectroscopy (EIS) analysis exhibits the pure electronic behavior at hydrogen atmosphere. The maximum power density of ANZ-GDC composite anode based solid oxide fuel cell has been achieved 705mW/cm 2 at 550 o C.