Patent Application
20220173408
The present invention relates to a solid oxide fuel cell (SOFC) and, more particularly, to a SOFC with a scandium-doped nickel felt anode collector.
Solid oxide fuel cells (SOFCs) are electrochemical energy conversion device which converts various fuels based on hydrocarbons (natural gas, LPG) into electricity and heat with an unparalleled fuel-to-electric conversion efficiency among other types of fuel cells (Stambouli, A, et al. “Solid oxide fuel cells (SOFCs): a review of an environmentally clean and efficient source of energy.” Renewable and sustainable energy reviews 6.5 (2002): 433-455; Wang, Wei, et al. “Progress in solid oxide fuel cells with nickel-based anodes operating on methane and related fuels.” Chemical reviews 113.10 (2013): 8104-8151). One of the key barriers to widespread deployment of the SOFC has been its high cost associated with its high temperature of operation, typically in the 800-1000° C. This high operating temperature enables fuel flexibility (Eguchi, K., et al. “Fuel flexibility in power generation by solid oxide fuel cells.” Solid State Ionics 152 (2002): 411-416). However, this high operating temperature tends to use of expensive sealant and precious metals current collection for cell operation. During cell operation, hydrogen oxidation reaction (HOR) occurred at the interface of the anode-electrolyte following to the oxygen reduction reaction (ORR) at the cathode, where the current measurement must be carried out in this high operating temperature with a wide range of partial pressure ranging p(O)2 10−15˜10−1 bar (Atkinson, A. et al. (2011). Advanced anodes for high-temperature fuel cells. In Materials For Sustainable Energy: A Collection of Peer-Reviewed Research and Review Articles from Nature Publishing Group (pp. 213-223).
Therefore specific material having high electronic conductivity; chemically inert; compatible thermal expansion; as the current collectors are required for reliable operation of SOFC (Guillodo, M. et al. “Electrochemical properties of Ni—YSZ cermet in solid oxide fuel cells: effect of current collecting.” Solid State Ionics 127.1-2 (2000): 99-107; Steele, B. C., & Heinzel, A. (2011). Materials for fuel-cell technologies. In Materials For Sustainable Energy: A Collection of Peer-Reviewed Research and Review Articles from Nature Publishing Group (pp. 224-231); Deleebeeck, Lisa, and Kent Kammer Hansen. “Hybrid direct carbon fuel cell performance with anode current collector material.” Journal of Electrochemical Energy Conversion and Storage 12.6 (2015): 064501). The essential prerequisite for the consistent operation of the cell must have a stable current collector with good contact with the electrode over a prolonged period of operation, furthermore, in an anode, the current collector must have the potential to withstand the robust condition low partial pressure of oxygen, coking, and sulfur poisoning (Flesch, U., et al. “Properties of nickel mesh as a methane steam reforming catalyst and its application in SOFCs.” ECS Proceedings, Volumes 1999 (1999): 612-620) Generally, in lab scale, small button cell the precious metal (Pt; Au, and Ag) as the current collector are often be used as anode current collector, these metals act as good current collectors (Liu, Meilin, et al. “Rational SOFC material design: new advances and tools.” Materials Today 14.11 (2011): 534-546; Sengodan, Sivaprakash, et al. “Layered oxygen-deficient double perovskite as an efficient and stable anode for direct hydrocarbon solid oxide fuel cells.” Nature materials 14.2 (2015): 205) However, the high cost of the precious metals current collector is a major hurdle for commercialization (Hiraiwa, Chihiro, et al. “Application of Ni Porous Metal to Solid Oxide Fuel Cells.” Sei Technical Review 83 (2016): 59).
Interestingly current collector is exhibiting catalytic activity depending on the choice of materials and configuration. The catalytic activity of the current collector not only that improve the performance but also the durability of the cell. In these aspects, many research is reported previously (Casarin, Michele, and Vincenzo M. Sglavo. “Effect of the Current Collector on Performance of Anode-Supported Microtubular Solid Oxide Fuel Cells.” Journal of Fuel Cell Science and Technology 12.3 (2015): 031005; Jiang, S. P. et al. “Effect of contact between the electrode and current collector on the performance of solid oxide fuel cells.” Solid State Ionics 160.1-2 (2003): 15-26; Li, Tao et al. “A dual-structured anode/Ni-mesh current collector hollow fiber for micro-tubular solid oxide fuel cells (SOFCs).” Journal of Power Sources 251 (2014): 145-151; Cantos-Gómez, A. et al. “Ag as an alternative for Ni in direct hydrocarbon SOFC anodes.” Fuel Cells 11.1 (2011): 140-143; Canavar, Murat, and Yuksel Kaplan.
“Effects of mesh and interconnector design on solid oxide fuel cell performance.” International Journal of Hydrogen Energy 40.24 (2015): 7829-7834. Keeping the main objective as an efficient and reliable operation under hydrocarbon fuel with reasonable cost, the development of an alternative collector other than precious metals is great importance for practical deployment of SOFC. The Ni-current collectors (Ni-foam, Ni-fiber felt, Ni-mesh) and stainless steel are more suitable in these aspects, as they are stable under the anodic condition and compatible with the state-of-the-art nickel cermet anodes (Weber, A., Sauer, B., Muller, A. C., Herbstritt, D., & Ivers-Tiffee, E. (2002). Oxidation of H2, CO and methane in SOFCs with Ni/YSZ-cermet anodes. Solid State Ionics, 152, 543-550). Specifically, the Ni-foam based current collector is exceptional quality, because these are cost-effective, and exhibits high electronic conductivity, substantial catalytic activity compared to the precious metal current collector, the polarization resistance value for HOR activity of the most common current collector are in the order: Ni<Pt<Au. However, the palladium (Pd) as current collector exhibits higher cell performance than the Ni— current collector due to the higher catalytic activity for hydrogen oxidation. Flesch et al. reported the effect of the pre-oxidized nickel mesh current collector followed by reduction on the Ni—YSZ anode supported SOFC, resulting in high catalytic activity for methane steam reforming thus the performance of the cell improved compared to the untreated Ni-foam current collector. While, Hiraiwa et al., studied alloying the nickel (Ni) with tin (Sn) to form a porous Ni—Sn current collector for the SOFC stacks, This Ni—Sn exhibits high thermal oxidation resistance and gas diffusion performance which resulting in high power density equivalent to the Pt-mesh current collector.
The internal reforming of carbon-containing fuels over nickel-based cermet anode promotes carbonaceous deposit on the surface and inside the anode microstructure. These issues of the coking and carbon deposition blocked the active reaction sites resulting degradation of the cell performance and breakdown of the cell (Park, Seungdoo, John M. Vohs, and Raymond J. Gorte. “Direct oxidation of hydrocarbons in a solid-oxide fuel cell.” Nature 404.6775 (2000): 265).
Many innovative strategies have been devised to respond the above drawbacks, such as by increasing the S/C (steam to carbon ratio) contents in the fuel, using CeO2 and Ni—Cu or Ni—Co alloy in the cermet, or replaced the nickel-cermet with perovskite anode. However, this practice leads to a loss of the performance and efficiency of compared to the Ni-based cermet (Lanzini, A. et al. (2013). The durability of anode supported Solid Oxides Fuel Cells (SOFC) under direct dry-reforming of methane. Chemical engineering journal, 220, 254-263; Kishimoto, H. et al. (2007). Stability of Ni-based anode for direct hydrocarbon SOFCs. Journal of Chemical Engineering of Japan, 40(13), 1178-1182; Xiao, J. et al. (2014). Deactivation of the nickel-based anode in solid oxide fuel cells operated on carbon-containing fuels. Journal of Power Sources, 268, 508-516; Iida, T. et al. (2007). Internal refoi filing of SOFCs carbon deposition on fuel electrode and subsequent deterioration of cell. Journal of the !Electrochemical Society, 154(2), B234-B241).
U.S. Pat. No. 8,455,154 discloses a solid oxide fuel cell (SOFC) including a plurality of subassemblies. Each subassembly includes at least one subcell of a first electrode, a second electrode and an electrolyte between the first and second electrodes. A first bonding layer is at the second electrode, and an interconnect layer is at the first bonding layer distal to the electrolyte. A second bonding layer that is compositionally distinct from the first bonding layer is at the interconnect layer, whereby the interconnect partitions the first and second bonding layers. A method of fabricating a fuel cell assembly includes co-firing at least two subassemblies using a third bonding layer that is microstructurally or compositionally distinct from the second bonding layer.
The electrochemical test in humidified methane under potentiostatic condition reveals that the ohmic and polarization resistance are lessened with cell operation time along with degradation observed in the cell with the nickel-felt current collector. There is a long-felt and unmet need to provide a current collector demonstrating improved stability.
It is hence one object of the invention to disclose a solid oxide fuel cell (SOFC) assembly connectable to a source of a hydrocarbon fuel; the SOFC assembly comprising at least one SOFC; each SOFC further comprising: (a) an anode support member having a nickel felt-made anode current collector; (b) an electrolyte layer disposed on the anode support member; and (c) a cathode having a cathode current collector; the cathode disposed on the electrolyte layer.
It is a core purpose of the invention to provide the nickel felt-made anode current collector doped with scandium.
Another object of the invention is to disclose the cathode, anode, and electrolyte which are nested within a ceramic bond.
A further object of the invention is to disclose the cathode made of a LSM/ScSZ composite material.
A further object of the invention is to disclose the anode support member made of sintered Ni—ScSZ.
A further object of the invention is to disclose the electrolyte layer which is a ScSZ paste.
A further object of the invention is to disclose the felt-made anode current collector doped with scandium made by spraying solution of Sc2O3 in HNO3.
A further object of the invention is to disclose a method of manufacturing a solid oxide fuel cell; the method comprising steps of: (a) manufacturing an anode support member by sintering NiO and ScSZ; (b) spraying an electrolyte ScSZ layer on the anode support member; (c) sintering the electrolyte ScSZ layer; (d) printing a cathode layer of LSM-ScSZ paste on the electrolyte ScSZ layer; (e) sintering the cathode layer; (f) manufacturing anode and cathode current collectors; and (g) connecting the anode and cathode current collectors to the anode and cathode, respectively.
It is a core purpose of the invention to provide the step of manufacturing anode and cathode current collectors comprising manufacturing the anode current collector by spraying solution of Sc2O3 in HNO3 onto a nickel felt.
In order to understand the invention and to see how it may be implemented in practice, a plurality of embodiments is adapted to now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which
The following description is provided, so as to enable any person skilled in the art to make use of the invention and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, are adapted to remain apparent to those skilled in the art, since the generic principles of the present invention have been defined specifically to provide an anode supported solid oxide fuel cell and a method manufacturing the same.
Scandium modified Ni-fiber felt as the anode current collector for a hydrocarbon fuel (CH4) SOFC by using the. Nickel is an effective catalyst used for oxidation and cracking of the hydrocarbon (Dissanayake, Dhammike, et al. “Partial oxidation of methane to carbon monoxide and hydrogen over a Ni/Al2O3 catalyst.” Journal of Catalysis 132.1 (1991): 117-127; Amin, A. M. et al. (2012). Hydrogen production by methane cracking using Ni-supported catalysts in a fluidized bed. International journal of hydrogen energy, 37(14), 10690-10701; Choudhary, T. V. et al. (2001). Hydrogen production via catalytic decomposition of methane. Journal of catalysis, 199(1), 9-18; Yamaji, Katsuhiko, et al. “Feasibility of Ni-based cermet anode for direct HC SOFCs: Fueling ethane at a low S/C condition to Ni—ScSZ anode-supported cell.” Journal of power sources 159.2 (2006): 885-890) Meanwhile, the scandium exhibits considerable catalytic activity for methane conversions and methane selectivities (Fokema, M. D., & Ying, J. Y. (1998). The selective catalytic reduction of nitric oxide with methane over scandium oxide, yttrium oxide, and lanthanum oxide. Applied Catalysis B: Environmental, 18(1-2), 71-77; Catalytic Functionalization of Hydrocarbons by s-Bond-Metathesis Chemistry: Dehydrosilylation of Methane with a Scandium Catalyst, Aaron D. Sadow T. Don Tilley Prof, Angew. Chem. Int. Ed. 2003, 42, No. 7, 803-805). It is expected that the scandium modified Ni-mesh improved the partial oxidation of methane resulting limitation of the carbon formation on the anode, enhance the efficiency and durability.
Reference is now made to
The slurry composition of the NiO—ScSZ anode support layer is shown in Table-1. At first, the NiO and ScSZ powder and pore-former (cornstarch) are ball-milled in the azeotropic mixture of ethanol-MEK (2-butanone) with dispersant triethanolamine (TEA) for 24 h using zirconia ball (4 mm). After homogenization of the powders in the solvent system, the primary plasticizer Dibutyl phthalate (DBP) and secondary plasticizer polyethylene glycol (PEG-400) were mixed to the slurry and milled for 6 h, finally, the binder polyvinyl butyral (PVB) is mixed into the slurry and further milled for 48 h. The slurry is de-aired in a polycarbonate vacuum desiccators (Sanplatec) applying the vacuum of 100 psi for 2 h. The viscosity of the slurry then measured by Brookfield LV viscometer (model—MLVT115) using Spindle-LV4. The measured viscosity of the slurry was 8550 and 6730 cps at 20 rpm and 50 rpm, respectively, at room temperature. The slurry then tape cast on a silicon-coated Mylar film (Tape casting warehouse, inc.) by MTI automatic thick film coater (Model—MSK-AFA-III) and doctor blade (Micrometer Adjustable Film Applicator −100 mm). The green film thickness was maintained to 1.5 mm which was dried at room temperature overnight.
The green tape-shaped to 6.4×6.4 cm2 and sintered at multiple steps for binder burn out with a ramp 0.5° C. min−1, finally pre-sintered at 1200° C. for 4 h. The pre-sintered anode support was then polished by sandpaper, the anode functional layer is sprayed onto the anode support followed by drying and binder burn out at 400° C. for 2 h. Finally the electrolyte (10ScSZ) slurry was spray coated onto the AFL layer. After drying the electrolyte layer the half-cell was sintered at 1400° C. for 4 h. Composite cathode paste LSM-ScSZ (50:50 wt. %) was prepared by mixing the LSM powder (LSM-20 HP, Fuel cell materials, SSA=11.8 m2 /g), 10Sc1CeSZ (ScCeSZ-TC, Fuel cell materials, SSA=10.6 m2/g) with ink vehicle VEH (Fuel cell materials) in the centrifugal mixer (Thinky corp. Inc, ARE 310), the powder to ink vehicle ratio=1:1 wt/wt. The cathode paste was finally screen printed on the electrolyte (active area=16 cm2) and sintered at 1050° C. for 2 h.
Commercial nickel fiber felt (Magnex co.ltd, Japan), wire thickness=0.05 cm, the diameter of the nickel wire ˜7×10−3 cm and areal density ˜0.0865 gm cm−2 were used for current collector preparation (see
The cell was tested by the Scribner test station (855 SOFC), at first the ASC is fixed between a pair of Crofer manifolds (5.1×5.1 cm2), two gaskets (Thermiculite 866 Flexitallic, USA) are used for sealing, the anode current collector (Ni or Sc: Ni-mesh) and the cathode current collector are fixed on the specified manifold using Ni-paste and LSM-paste (fuel cell materials), respectively, the Crofer 22APU wire is used as the current lead for both anode and current. The cell with ‘Sc: Ni-felt’ and ‘Ni-felt’ current collector are named as ‘S-cell’ and respectively, in the manuscript. After stacking the cell, ceramic bond (ceramabond 552, Aremco product Inc, USA) is brush coated to seal the manifold. The schematic of the stacking is shown in
The most common anode supported cell (ASC) configuration for hydrocarbon fuel cells is Ni-ScSCZ//ScSZ//LSM-SCSZ. The microstructure of the cross-section of the anode-supported cell and the corresponding EDX analysis is shown in
Nevertheless, both cell has identical in configuration, microstructure, and component, so the higher in the cell performance of S-cell mostly attributed to the superior catalytic activity of the Sc: Ni-fiber felt compared to Ni-felt current collector. To confirm the effect of the current collector, the electrochemical impedance of the single cell is measured, due to the limitation of the test station potentiostat and frequency analyzer the impedance spectra of the cell are recorded with a load of 3.2 A (j=200 mAcm−2). The Nyquist plot of P-cell and S-cell are shown in
The XRD analysis of the felt and anode surface of S-cell and P-cells are shown in
Furthermore, the microstructure of the cells was investigated, the FESEM analysis of the NiO—ScSZ after the electrochemical tested cell is shown in
To get the evidence of partial oxidation of methane on the current collector, the methane cracking experiment was carried out in a horizontal quartz tube reactor at 700° C. for 5 h. The Ni-felt and Sc: Ni-felt (Sc=1 wt %) are kept inside the reactor about 0.2 Lmin−1 CH4 (3% H2O) are flown, after the methane cracking experiments the reactor are cooled down under purging of Argon. The photographic image of the Ni-felt, Sc: Ni-felt and the corresponding figure after methane exposed is shown in
A scandium-modified nickel anode current collector is developed for hydrocarbon fuel SOFC. The electrochemical test in humidified methane under potentiostatic condition reveals that the ohmic and polarization resistance are lessened with cell operation time, while degradation observed in the cell with the pristine nickel current collector. The galvanostatic test confirms that the cell with the modified current collector exhibits better stability. A significant improvement of cell performance (˜36%) is achieved using the scandium modified current collector. The microstructure and phase analysis accomplishes the partial oxidation of methane on the scandium modified nickel current collector is the main advantages on the improvement of the performance and the stability of the state of the art anode supported cell under hydrocarbon fuel.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IL2019/051002 | 9/8/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62807785 | Feb 2019 | US |
