Anode fabrication for solid oxide fuel cells: Electroless and electrodeposition of nickel and silver into doped ceria scaffolds (original) (raw)
Related papers
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.
Journal of The Electrochemical Society
Nickel was electrodeposited on porous Ag/GDC (silver/Ce 0.9 Gd 0.1 O 2-x) scaffolds and dense Ag/GDC composites for the fabrication of SOFC electrodes and catalytic membranes respectively. To control the distribution and amount of nickel deposition on the Ag/GDC surfaces; first, a systematic cyclic voltammetry study of nickel electrodeposition from a Watts bath on silver foils was carried out to understand the influence of operating conditions on the electrodeposition process. From the cyclic voltammetry study, it can be concluded that suitable operating conditions for nickel electrodeposition into porous Ag/GDC scaffolds and catalytic membranes are: 1.1 M Ni 2+ concentration in Watts bath; deposition potential between −0.65 to −1.0 V vs. Ag/AgCl; a temperature at 55 • C; sodium dodecyl sulfate (SDS) as the surfactant; pH 4.0 ± 0.2 and an agitation rate of 500 rpm. It was observed that the nickel surface microstructure changed with the deposition current densities due to the co-evolution of H 2. Pulse and continuous electrodeposition modes allow nickel to be deposited throughout porous Ag/GDC scaffolds and onto catalytic membranes. The pulse electrodeposition mode is favored as this is shown to result in an even Ni distribution within the porous scaffolds at minimum H 2 pitting.
Journal of Power Sources, 2006
A Ni/scandia-stabilized zirconia (ScSZ) cermet anode was modified by coating with nano-sized gadolinium-doped ceria (GDC, Gd 0.2 Ce 0.8 O 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 2 O 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 0.2 Ce 0.8 O 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 2 O 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.
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...
Electrochemical performance of Ni-based anodes for solid oxide fuel cells
Journal of Applied Electrochemistry, 2009
The catalytic activity of Ni-based anodic materials was investigated in complete solid oxide fuel cells (SOFCs) by electrochemical analysis. Button cells, consisting of supporting yttria-stabilized zirconia (YSZ) electrolyte layer, (La 1-x Sr x ) y MnO 3 (LSM) cathode and (cermet) Ni 0.5 Co 0.5 -YSZ anode were employed. Powders for anodes were obtained by wet impregnation. This procedure allowed easy production of composite electrodes with homogeneous distribution of phases and controlled microstructure. Two electrodes impedance spectroscopy was carried out at different temperatures and partial pressures of reacting gases in order to evaluate contribution of each component to overall cell losses. Current-voltage characteristic curves were also collected. Feeding with CH 4 was tested and compared to H 2 . No deterioration of cell performance due to carbon formation at anode was observed over a test period of 100 h.
Nano Energy, 2014
Gadolinium-doped ceria (GDC) nanocubes with highly reactive {001} facets were synthesized as an anode material for solid-oxide fuel cells by organic-ligand-assisted hydrothermal treatment with a water-soluble amino acid, 6-amino hexanoic acid (AHA). An aerosol technique was applied to fabricate a NiO-GDC nanocube composite with water as a green solvent. The NiO-GDC nanocube composite was easily sintered even at a temperature of 1100 °C, while the conventional NiO-GDC composite covered with the most stable {111} facets was sintered at 1300 °C. Sintering at such a low temperature inhibited undesirable coarsening of NiO and GDC particles, resulting in an enlarged, triple-phase boundary (TPB). The NiO-GDC nanocube composite anode with the enlarged TPB exhibited a rather low area specific resistance of 0.14 Ω•cm 2 compared with the conventional NiO-GDC composite anode's resistance of 0.58 Ω•cm 2 when operated at 600 °C.
Nickel/gadolinium-doped ceria anode for direct ethanol solid oxide fuel cell
International Journal of Hydrogen Energy, 2014
This report investigates the properties of nickel/gadolinium-doped ceria (Ni/GDC) as anode material for bio-ethanol fueled SOFC. The Ni/GDC cermets with 18 and 44 wt.% Ni were prepared by a hydrothermal method. Ethanol decomposition, steam reforming, and partial oxidation of ethanol were studied using a fixed-bed reactor at 1123 K. Carbon was formed only under dry ethanol for both catalysts. The addition of water or oxygen to the feed inhibited the formation of carbon. Ni/GDC was used as the anode current collector layer and as a catalytic layer in single cells tests. No deposits of carbon were detected in single cells with Ni/GDC catalytic layer after 50 h of continuous operation under direct (dry) ethanol. This result was attributed to the catalytic properties of the Ni/GDC layer and the operation mechanism of gradual internal reforming, in which the oxidation of hydrogen provides the steam for ethanol reforming, thus avoiding carbon deposition.
NiO-Ce 0.8 Gd 0.2 O 2−δ cermet anode powders with flake-shaped particles have been synthesized using a unique micro-emulsion-mediated solvothermal process. With an increase in the amount of urea used as a precipitation agent, the particles change from plate to flake shape in a morphological transition. Well-developed flake-shaped anode powders can be obtained from 24 h of solvothermal treatment. The polarization resistance at 800 1C in humidified H 2 and the activation energy of the anode synthesized with 1:4 salt to urea ratio and the solvothermal treatment duration of 24 h are 0.01 Ω cm 2 and 0.53 eV, respectively. In accordance with the polarization resistance results, a single cell with the MEST4 anode shows a high maximum-power density of 0.32 W cm −2 , at 800 1C with a humidified H 2 fuel.