I am a PhD Researcher that focuses on characterising the microstructural behaviour of superalloys.
Pinboard displaying all the novel research areas within metal-supported solid oxide fuel cells
In 10 seconds? Today we see a lot of commercial applications of solid oxide fuel cells (SOFC’s) – London buses for one. The main benefit of SOFC’s is that they produce much less greenhouse gases as opposed to conventional methods. However, much more research is required to fully explore the potential of this energy method.
One interesting development in solid oxide fuel cells was the innovation of metal-supported solid oxide fuel cells. Metal supported solid oxide fuel cells have numerous advantages over conventional ceramic SOFC’S, such as; low material cost, higher thermal shock resistance and much better durability. The drive to reduce the price of fuel cells overall is a global issue and research is ongoing to find ways to reduce the material and also the manufacturing cost.
Don’t believe it? One particular paper has carried out a review of the developments within metal-supported solid oxide fuel cells, with particular interest in the work that has been carried out since 2010 on reducing the cost of these devices - see article “Recent developments in metal-supported solid oxide fuel cells”.
Okay, so how do SOFC’s generate power? In simple terms, a chemical reaction occurs within the SOFC causing the fuel (commonly hydrogen or natural gas) into electricity.
So how does this reaction takes place?
Firstly, we need to understand that an SOFC is made up of three main components; anode, cathode and an electrolyte. To begin the process, hydrogen is passed into the fuel cell at the anode side and at this point its electrons are removed – causing the hydrogen atoms to become ionised and as a consequence of being ionised they are now carrying a positive electrical charge. These ionised hydrogen atoms then pass through the electrolyte (sandwiched between the cathode and anode).
Oxygen enters the fuel cell from the cathode side and combines with the ionised hydrogen atoms that have passed through the electrolyte component of the fuel cell and also combines with the removed hydrogen electrons that have passed through the circuit.
Abstract: Combustion synthesis (CS) in thermal explosion mode under conditions of controlled heat loss is used for synthesis of thin Ni-Al porous plates. In the present work, compacted Ni-Al elemental powder mixtures placed between heat-removing clamp plates are heated in a furnace at 25 K/min up to 1000 K under the uniaxial load up to 1.2 MPa with further heat treatment at the temperature of 1100 K. The effects of the Ni/Al mass ratio, reagent powders size, porosity and thickness of the reacting samples as well as conditions of heat-exchange during the CS on the reaction parameters have been studied. Based on the thermocouple measurements, the temperature and timing characteristics of the CS process have been calculated. The phase composition evolution during the process has been analyzed using X-ray diffraction and energy-dispersive X-ray spectroscopy. Special attention has been paid to the study of the following characteristics of synthesized materials: porosity parameters, gas permeability and mechanical properties. Due to the high strength of synthesized materials and formation of relatively homogenous structure with proper pores size and gas permeability, the synthesized porous Ni-Al plates can be considered as good supporting substrate for application in metal-supported solid oxide fuel cells.
Pub.: 25 Nov '16, Pinned: 18 Apr '17
Abstract: A novel metal-supported solid oxide fuel cell has been developed that is capable of operating at temperatures of 500–600 °C. The rationale behind the materials used to construct this fuel cell type is given, and results are presented from cell testing on hydrogen and reformed natural gas, including durability trials of some 2500 h duration. This new fuel cell variant is shown to be tolerant of carbon monoxide, durable, robust to thermal and redox cycling, and capable of delivering technologically relevant power densities.
Pub.: 01 Jun '04, Pinned: 18 Apr '17
Abstract: Novel high permeable porous Ni‐Mo substrates with different area densities of straight gas flow channels are successfully developed to improve the hydrogen fuel gas and the water byproduct diffusion in the anode and supporting substrate. Metal‐supported cell A, cell B and cell C with 5 × 5 cm2 supporting substrates are fabricated by atmospheric plasma spraying processes, these cells have the material structure of Ni‐Mo/LSCM (La0.75Sr0.25Cr0.5‐Mn0.5O3–δ)/NiO‐LDC(Ce0.55La0.45O2–δ)/SDC(Sm0.15Ce0.85O3–δ)/LSGM (La0.8Sr0.2Ga0.8Mg0.2O3–δ)/SSC(Sm0.5Sr0.5CoO3–δ). Cell A is supported by a conventional porous Ni‐Mo substrate without straight gas flow channels, cell B and cell C are supported respectively by the novel high permeable porous Ni‐Mo substrates with 1.5 and 2.73 channels per square centimeter. The power densities at 0.8 V and 750 °C are 550, 998 and 1,161 mW cm−2 for cell A, cell B and cell C respectively. The 100 h durability test at the constant current density of 400 mA cm−2 and 650 °C shows cell B and cell C have smaller degradation rates than cell A. The results obtained from AC impedance and circuit model analyses indicate that the electrolyte ohm and the cathode polarization resistances are significantly reduced by introducing straight gas flow channels into the supporting substrate.
Pub.: 15 Mar '16, Pinned: 18 Apr '17
Abstract: While porous metal-supported solid oxide fuel cells (PMS-SOFCs) have potential to dramatically reduce the cost while enhancing the durability of SOFC technology, the available fabrication processes are still cumbersome and unsuitable for commercial applications. Here, we report our findings in exploring low-cost, additive, thermal spray processes suitable for large-scale manufacturing of PMS-SOFCs. The additive fabrication process starts with a porous metal support, on which a porous nickel-based anode layer and a dense electrolyte membrane are sequentially deposited. Then, a nanostructured La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode layer is applied using a liquid precursor high velocity oxygen fuel flame (LP-HVOF) spraying process. The polarization resistance of the LSCF cathode is reduced to 0.15 Ω cm2 at 600 °C and 0.025 Ω cm2 at 750 °C. The PMS-SOFCs display excellent performance, demonstrating peak power densities of 0.23, 0.65, 1.1, and 1.5 W cm−2 at 500, 600, 700, and 750 °C, respectively, while maintaining impressive stability (no observable change for more than 600 h at 650 °C). Our results suggest that thermal spraying has potential to be a low-cost and flexible process suitable for large-scale fabrication of commercial PMS-SOFCs.
Pub.: 07 Apr '16, Pinned: 18 Apr '17
Abstract: Solid oxide fuel cells (SOFCs) offer a promising technique for producing electricity by clean energy conversion through an electrochemical reaction of fuel and air. Plasma spraying could be a potential manufacturing route for commercial SOFCs, as it provides a distinct advantage especially in case of metal supported cells (MSCs) by allowing rapid processing at relatively low processing temperatures preventing thus the degradation of the metallic substrate. The objective of this work was to develop nickel/yttria stabilised zirconia (Ni/YSZ) anodes with high porosity and homogeneous phase distribution by atmospheric plasma spraying for MSCs. Various feedstock material approaches were explored in this study, both with single injection as well as separate injection of different feedstock materials , and with and without the use of pore formers to create additional porosity. The advantages and issues with each material route were investigated and discussed. It was shown that agglomerated Ni/YSZ/polyester feedstock material resulted in the best distribution of Ni and YSZ in the anode microstructure with homogeneous porosity. Subsequently, the Ni/YSZ/polyester material route with different amounts and size distributions of polyester was chosen to develop anode symmetrical cells using a commercial zirconia sheet as support for electrochemical testing. The Ni/YSZ/polyester anode powder with 10 wt.% standard size polyester exhibited the best electrochemical performance. The results show that plasma spraying of the agglomerated Ni/YSZ/polyester could be a promising route to achieve high performance and rapid production anodes without using the carcinogenic nickel oxide.
Pub.: 09 Sep '16, Pinned: 18 Apr '17
Abstract: The electrochemical properties and long-term performance of an in-situ composite cathode comprised of SmBa0.5Sr0.5Co2O5+δ (SBSCO) and Ce0.9Gd0.1O2−δ (CGO91) are investigated for metal supported solid oxide fuel cell (MS-SOFC) application.
Pub.: 17 Nov '16, Pinned: 18 Apr '17
Abstract: Metal-supported solid oxide fuel cells (MSCs) have gained high attention as they offer a possibility to utilize solid oxide fuel cells (SOFCs) in mobile applications such as auxiliary power units in heavy duty vehicles. Cathode reliability is one of the main issues of MSC development, since cathodes tend to degrade rapidly after being in-situ activated during onset of the stack operation. In the present study, a novel sintering route for La0.58Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode material was developed. Sintering of the screen printed cathodes was performed before stack operation at 950 °C in reducing Ar atmosphere for 3 h. Under these conditions, severe oxidation of the metallic substrate and the Ni in the anode was avoided reliably.
Pub.: 16 Dec '16, Pinned: 18 Apr '17
Abstract: Metal-supported solid oxide fuel cells (MSCs) offer certain strategic advantages over the more conventional solid oxide fuel cells (SOFCs), which comprise only ceramic materials. Since alloys such as ferritic steels are very similar in their coefficient of thermal expansion (CTE) with ceramic components, viz., cerias, zirconias, and nickel oxide doped with either of them, they could provide excellent thermal cyclability while maintaining a strong interlayer bond. Therefore, in an anode-supported cell the entire NiO-ceramic support can be replaced by a ferritic steel porous support—the catalytically active NiO is therefore, a functional layer only. A huge savings in materials cost is achievable, because cerias and zirconias [usually doped with Y, Gd, Sm rare earth (RE) elements] are considerably more expensive that ferritic steels. Lowering the capital costs for SOFCs is an extensive global undertaking with US Department of Energy (DOE) laying down targets such as ~$ 200/kW for the stack itself, in order for SOFCs to become competitive with grid power costs and to offer a power source that promises 24 × 7 power supply for critical applications. This will eventually lead to a premier electricity generation device in the distributed power space, with the highest known electrical efficiencies (>50%). MSCs need very robust, high precision, and cost-effective manufacturing techniques, which are scalable to high volumes. One of the main goals in this review is to showcase some of the work done in this area since the last review (2010), and to assess the technology challenges, and new solutions that have emerged over the past few years.For further resources related to this article, please visit the WIREs website.
Pub.: 30 Mar '17, Pinned: 18 Apr '17