Publications
498 results found
Tariq F, Kishimoto M, Cooper SJ, et al., 2013, Advanced 3D Imaging and Analysis of SOFC Electrodes, ECS Transactions, Vol: 57, Pages: 2553-2562, ISSN: 1938-6737
Solid Oxide Fuel Cells (SOFC) are electrochemical devices where performance is dependent on reactions inside porous electrode microstructures; their complexity is inadequately described using 2D imaging. Here we use X-ray Nano-CT tomographic techniques to probe 3D electrode structures (anodes and cathodes) at micro-nanometer length scales produced using a focused ion beam. Subsequently, micro/nano structural changes in SOFC electrodes are followed and quantified to facilitate understanding changes that occur in shape, structures and morphology at high sub-100nm resolution. Time-resolved (4D) imaging revealed Ni-YSZ oxidation markedly increased above 500 ºC and LSCF densification at 700 ºC may close pores. Utilising 3D electrode data as geometric inputs for numerical models, revealed that increased strains were located at Ni-YSZ interfaces and at microstructure constrictions for both anodes and cathodes when heated. The results show nano/micro structural changes can affect the performance of SOFC electrodes. This combined experimental and modelling approach can help in establishing structure/performance relationships providing key insights important for transport, electrochemistry and strains in both SOFC anodes and cathodes and understanding sources of performance degradation.
Cooper SJ, Kishimoto M, Tariq F, et al., 2013, Microstructural Analysis of an LSCF Cathode Using In Situ Tomography and Simulation, ECS Transactions, Vol: 57, Pages: 2671-2678, ISSN: 1938-6737
Electrode tortuosity factor is a key input parameter in many fuel cell simulations. Three-dimensional microstructural data obtained from in-situ synchrotron X-ray nano-computed tomography is used as the basis for comparing five approaches to quantify the tortuosity factor. Three of these techniques are based on diffusivity simulations and showed strong correlation, but had consistently different absolute values. A random walk method showed a good degree of correlation to the diffusive approaches, but had the largest values overall. Lastly, a calculation that used a mean pore centroid approach showed little correlation to any of the other three methods, but compared well with the conventional Bruggeman correlation. Due to the diffusive nature of the ionic transport in electrodes, the authors would recommend calculating tortuosity factors using a diffusive approach based on the voxels rather than a remeshed volume.
Brandon NP, Corcoran D, Cummins D, et al., 2013, Development of metal supported solid oxide fuel cells for operation at 500-600 °c, Pages: 2900-2903, ISSN: 1059-9495
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. © 2013 ASM International.
Chakrabarti MH, Low CTJ, Brandon NP, et al., 2013, Progress in the electrochemical modification of graphene-based materials and their applications, Electrochimica Acta, Vol: 107, Pages: 425-440, ISSN: 0013-4686
Graphene is a 2D allotrope of carbon with exciting properties such as extremely high electronic conductivity and superior mechanical strength. It has considerable potential for applications in fields such as bio-sensors, electrochemical energy storage and electronics. In most cases, graphene has been functionalized and modified with other materials to prepare composites. This work reviews the electrochemical modification of graphene. Commencing with a brief history, a summary of several different means of modifying graphene to effect diverse applications is provided. This is followed by a discussion on different composite materials that have been prepared with reduced graphene oxide prior to moving onto a detailed consideration of six different methods of electrochemically modifying graphene to prepare composite materials. These methods involve cathodic reduction of graphene oxide, electrophoretic deposition, electro-deposition techniques, electrospinning, electrochemical doping and electrochemical polymerization. Finally a consideration on the applications of electrochemically modified graphene composite materials in various fields is presented prior to discussing some prospects in enhancing the electrochemical process to realize excellent and economic composite materials in bulk.
Kalyvas C, Kucernak A, Brett D, et al., 2013, Spatially resolved diagnostic methods for polymer electrolyte fuel cells: a review, WILEY INTERDISCIPLINARY REVIEWS-ENERGY AND ENVIRONMENT, Vol: 3, Pages: 254-275, ISSN: 2041-8396
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- Citations: 16
Rhazaoui K, Cai Q, Adjiman CS, et al., 2013, Towards the 3D modeling of the effective conductivity of solid oxide fuel cell electrodes: I. Model development, CHEMICAL ENGINEERING SCIENCE, Vol: 99, Pages: 161-170, ISSN: 0009-2509
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- Citations: 13
Millichamp J, Mason TJ, Brandon NP, et al., 2013, A study of carbon deposition on solid oxide fuel cell anodes using electrochemical impedance spectroscopy in combination with a high temperature crystal microbalance, JOURNAL OF POWER SOURCES, Vol: 235, Pages: 14-19, ISSN: 0378-7753
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- Citations: 28
Maher RC, Duboviks V, Offer GJ, et al., 2013, Raman Spectroscopy of Solid Oxide Fuel Cells: Technique Overview and Application to Carbon Deposition Analysis, FUEL CELLS, Vol: 13, Pages: 455-469, ISSN: 1615-6846
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- Citations: 41
Somalu MR, Yufit V, Brandon NP, 2013, The effect of solids loading on the screen-printing and properties of nickel/scandia-stabilized-zirconia anodes for solid oxide fuel cells, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 38, Pages: 9500-9510, ISSN: 0360-3199
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- Citations: 33
Chakrabarti MH, Brandon NP, Hashim MA, et al., 2013, Cyclic Voltammetry of Iron (III) Acetylacetonate in Quaternary Ammonium and Phosphonium Based Deep Eutectic Solvents, INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE, Vol: 8, Pages: 9652-9676, ISSN: 1452-3981
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- Citations: 20
Somalu MR, Yufit V, Shapiro IP, et al., 2013, The impact of ink rheology on the properties of screen-printed solid oxide fuel cell anodes, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 38, Pages: 6789-6801, ISSN: 0360-3199
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- Citations: 27
Cooper SJ, Eastwood DS, Gelb J, et al., 2013, Image Based Modelling of of Microstructural Heterogeneity in LiFePO4 Electrodes for Li-ion Batteries, Journal of Power Sources, Vol: 247, Pages: 1033-1039, ISSN: 0378-7753
Battery and fuel cell simulations commonly assume that electrodes are macro-homogeneous and isotropic. These simulations have been used to successfully model performance, but give little insight into predicting failure. In Li-ion battery electrodes, it is understood that local tortuosity impacts charging rates, which may cause increased degradation. This report describes a novel approach to quantifying tortuosity based on a heat transfer analogy applied to X-ray microscopy data of a commercially available LiFePO4 electrode. This combination of X-ray imaging and image-based simulation reveals the microscopic performance of the electrode; notably, the tortuosity was observed to vary significantly depending on the direction considered, which suggests that tortuosity might best be quantified using vectors rather than scalars.
Mook WT, Aroua MK, Chakrabarti MH, et al., 2013, The application of nano-crystalline PbO<sub>2</sub> as an anode for the simultaneous bio-electrochemical denitrification and organic matter removal in an up-flow undivided reactor, ELECTROCHIMICA ACTA, Vol: 94, Pages: 327-335, ISSN: 0013-4686
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- Citations: 29
Lanzini A, Leone P, Guerra C, et al., 2013, Durability of anode supported Solid Oxides Fuel Cells (SOFC) under direct dry-reforming of methane, CHEMICAL ENGINEERING JOURNAL, Vol: 220, Pages: 254-263, ISSN: 1385-8947
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- Citations: 113
Ruiz-Trejo E, Boldrin P, Lubin A, et al., 2013, Silver-ceria composites for oxygen separation from air, 224th Electrochemical society meeting
Wu B, Yufit V, Campbell J, et al., 2013, Simulated and experimental validation of a fuel cell-supercapacitor passive hybrid system for electric vehicles, IET Conference Publications, Vol: 2013
The concept of a fuel cell-supercapacitor hybrid system involves the direct coupling of the two devices to achieve the same benefits of hybridisation but without the need for costly DCDC converters. Using an experimentally validated steady state fuel cell model and a transmission line based supercapacitor model, it has been shown that the passive hybridisation allows for efficiency gains of approximately 16% compared to a pure fuel cell system. Under load, the supercapacitors meets the peak power requirement due to their lower impedance giving the FC time to ramp up. Under no load conditions, the fuel cell gradually charges the supercapacitors back to the steady state thermodynamic equilibrium potential. A fast fourier transform analysis of the respective loads under an automotive drive cycle showed that the supercapacitors act as a low pass filter, reducing the magnitude of load oscillations from the fuel cell. This therefore addresses two of the main modes of fuel cell degradation in automotive applications: rapid power cycling and no load idling.
Guerra C, Lanzini A, Leone P, et al., 2013, Comparison of the catalytic properties of SOFC anode supports under dry reforming of methane, Pages: 73-74
The work investigates the catalytic properties of different SOFC anode substrates towards the chemical conversion of methane and carbon dioxide into H2 and CO-rich mixtures. The analysis is carried out by means of experiments in micro-reactor configuration. A mass spectrometer is provided to analyze the composition of the gas mixture leaving the reactor and thus allowing the evaluation of methane conversion rate. Furthermore, Temperature Programmed Oxidation (TPO) experiments are performed on the anode samples aiming at the analysis of material activity towards the cracking reaction of methane. Anode substrates based on different materials and microstructures are taken into account. The work features the effect of materials' composition and microstructure on the methane conversion rate and carbon cracking.
Mazur C, Contestabile M, Offer GJ, et al., 2013, Understanding the automotive industry: German OEM behaviour during the last 20 years and its implications, World Electric Vehicle Journal, Vol: 6, Pages: 1054-1067, ISSN: 2032-6653
This work presents a study of how the automotive industry has responded in the last 20 years to pressures driven by economic and environmental issues, and by the transition towards electric mobility. Timelines for the major German automotive OEMs are presented to understand the industry's behaviour in the past in order to design suitable policies that are appropriate to reach future goals around the electrification of road transport. Based upon a comparison of the pressures arising in the automotive sector and the companies' behaviour with regard to technology choice and R&D, a set of hypotheses concerning this behaviour is then presented.
Clague R, Marquis AJ, Brandon NP, 2013, Time independent and time dependent probability of failure of solid oxide fuel cells by stress analysis and the Weibull method, JOURNAL OF POWER SOURCES, Vol: 221, Pages: 290-299, ISSN: 0378-7753
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- Citations: 21
Maher RC, Duboviks V, Offer G, et al., 2013, In-operando Raman Characterization of Carbon Deposition on SOFC Anodes, 13th International Symposium on Solid Oxide Fuel Cells (SOFC-XIII), Publisher: ELECTROCHEMICAL SOC INC, Pages: 1619-1626, ISSN: 1938-5862
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- Citations: 2
Troxler Y, Wu B, Marinescu M, et al., 2013, The effect of thermal gradients on the performance of lithium ion batteries, Journal of Power Sources, Pages: accepted-accepted, ISSN: 0378-7753
Abstract An experimental apparatus is described, in which Peltier elements are used for thermal control of lithium-ion cells under isothermal and non-isothermal conditions, i.e. to induce and maintain thermal gradients. Lithium-ion battery packs for automotive applications consist of hundreds of cells, and depending on the pack architecture, individual cells may experience non-uniform thermal boundary conditions. This paper presents the first study of the impact of artificially induced thermal gradients on cell performance. The charge transfer resistance of a 4.8 Ah is verified to have a strong temperature dependence following the Arrhenius law. Thermal cycling of the cell, combined with slow rate cyclic voltammetry, allows to rapidly identify phase transitions in electrodes, due to the thermal effect of entropy changes. A cell with a temperature gradient maintained across is found to have a lower impedance than one held at the theoretical average temperature. This feature is attributed to details of the inner structure of the cell, and to the non-linear temperature dependence of the charge transfer resistance.
Somalu MR, Muchtar A, Baboli MG, et al., 2013, Understanding the Relationship between Ink Rheology and Film Properties for Screen-Printed Nickel/Scandia-Stabilized-Zirconia Anodes, 13th International Symposium on Solid Oxide Fuel Cells (SOFC-XIII), Publisher: ELECTROCHEMICAL SOC INC, Pages: 1321-1330, ISSN: 1938-5862
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- Citations: 9
Shearing PR, Brandon NP, 2013, Three Dimensional Reconstruction of Solid Oxide Fuel Cell Electrodes, SOLID OXIDE FUEL CELLS: FROM MATERIALS TO SYSTEM MODELING, Editors: Ni, Zhao, Publisher: ROYAL SOC CHEMISTRY, Pages: 178-199, ISBN: 978-1-84973-654-1
Yufit V, Hale B, Matian M, et al., 2013, Development of a Regenerative Hydrogen-Vanadium Fuel Cell for Energy Storage Applications, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 160, Pages: A856-A861, ISSN: 0013-4651
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- Citations: 38
Duboviks V, Maher RC, Offer G, et al., 2013, <i>In</i>-<i>Operando</i> Raman Spectroscopy Study of Passivation Effects on Ni-CGO Electrodes in CO<sub>2</sub> Electrolysis Conditions, 13th International Symposium on Solid Oxide Fuel Cells (SOFC-XIII), Publisher: ELECTROCHEMICAL SOC INC, Pages: 3111-3117, ISSN: 1938-5862
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- Citations: 12
Lomberg M, Ruiz-Trejo E, Offer G, et al., 2013, Characterization of a Novel Ni-impregnated GDC Electrode for Solid Oxide Fuel Cell and Electrolysis Cell Applications, SOLID OXIDE FUEL CELLS 13 (SOFC-XIII), Vol: 57, Pages: 1349-1357, ISSN: 1938-5862
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- Citations: 6
Parkes M, Refson K, d'Avezac M, et al., 2013, Determining Surface Chemistry and Vibrational Properties of SOFC Anode Materials Through <i>ab initio</i> Calculations, SOLID OXIDE FUEL CELLS 13 (SOFC-XIII), Vol: 57, Pages: 2419-2427, ISSN: 1938-5862
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- Citations: 2
Maskell WC, Brett DJL, Brandon NP, 2013, Improvements to Zirconia Thick-Film Oxygen Sensors, 17th Conference on Sensors and Their Applications, Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Mazur C, Contestabile M, Offer G, et al., 2012, Comparing electric mobility policies to transition science: Transition management already in action?, Pages: 123-128, ISSN: 2165-4387
Driven by sustainability issues as well as economic aspects, governments have been creating and applying policies and regulations with the aim of shifting national personal transport towards electric mobility. In this context, transition science offers insights into the relevant socio-technological systems and the process of transition. This paper gives an overview of transition science, and furthermore presents current policy making by the UK and German governments that aim to manage the shift to electric mobility. A comparison of the two different policies with transition science shows that there is an overlap between the applied policy making and theory, especially for the case of the UK. Although both governments do not explicitly follow transition management their actions can be explained with the help of transition science. However, it should be noted that transition science is still a young field which needs to be further developed in order to provide policy makers with tools that enable them to manage such transitions. ©2012 IEEE.
Maher RC, Offer G, Brandon NP, et al., 2012, In-situ Raman characterization of SOFC anodes, Materials Research Society Symposium Proceedings, Vol: 1385, Pages: 25-34, ISSN: 0272-9172
Solid oxide fuel cells (SOFCs) have many advantages when compared to other fuel cell technologies, particularly for distributed stationary applications. As a consequence they are becoming ever more economically competitive with incumbent energy solutions. However, as with all technologies, improvements in durability, efficiency and cost is required before they become feasible alternatives. Such improvements are enabled through improved understanding of the critical material interactions occurring during operation. Raman spectroscopy is a noninvasive and non-destructive optical characterization tool which is ideally suited to the study of these critical chemical processes occurring within operational SOFCs. In this paper we will discuss advantages of using Raman characterization for understanding these important chemical processes occurring within SOFCs. We will present the specific examples of the type of measurement possible and discuss the direction of future research. © 2012 Materials Research Society.
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