Publications
496 results found
Tariq F, Kishimoto M, Yufit V, et al., 2014, 3D imaging and quantification of interfaces in SOFC anodes, JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, Vol: 34, Pages: 3755-3761, ISSN: 0955-2219
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- Citations: 23
Kishimoto M, Lomberg M, Ruiz-Trejo E, et al., 2014, Enhanced triple-phase boundary density in infiltrated electrodes for solid oxide fuel cells demonstrated by high-resolution tomography, Journal of Power Sources, Vol: 266, Pages: 291-295, ISSN: 0378-7753
This paper, for the first time, demonstrates the three-dimensional imaging of nano-particle infiltrated Ni–GDC (gadolinia-doped ceria) electrodes using focused ion beam tomography. Microstructural parameters of the actual electrode microstructure are quantified, such as volume fraction, TPB density and mean particle/pore sizes. These microstructural parameters reveal that the infiltrated electrodes have eight times larger TPB density than conventional electrodes fabricated by powder mixing and sintering methods. Comparison between the infiltrated electrodes and conventional electrodes indicates that the infiltrated electrodes have a greater potential to independently control metal particle size, porosity and TPB density, which is a significant advantage in developing design optimized electrode microstructures.
Howey DA, Yufit V, Mitcheson PD, et al., 2014, Impedance measurement for advanced battery management systems
We present a fast, low-cost approach to measure battery impedance 'on-line' in a vehicle across a range of frequencies (1-2000 Hz). Impedance measurement has promise for improving battery management since it is a very effective non-invasive method of diagnosing the internal state of an electrochemical cell. It is useful for estimating temperature, ageing, state of charge (SOC) and for fault detection. The aim of this paper is firstly to explore the usefulness of impedance for estimating SOC, focusing on lithium-ion iron phosphate (LFP) and nickel manganese cobalt oxide (NMC) cells, and secondly to demonstrate the performance of a low cost impedance measurement system that uses an existing motor drive similar to that of an electric vehicle to excite the battery current. We find that measurements made with this system are accurate to within a few per cent of results from an expensive, bulky commercial system. For SOC estimation in NMC cells, the charge transfer resistance and SEI layer resistance vary significantly with SOC. In LFP cells the parameter variation is much less obvious, although the double layer capacitance of the full pack may be a useful indicator of SOC.
Mazur C, Contestabile M, Offer GJ, et al., 2014, Understanding the automotive industry: German OEM behaviour during the last 20 years and its implications
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.
Rhazaoui K, Cai Q, Adjiman CS, et al., 2014, Towards the 3D modeling of the effective conductivity of solid oxide fuel cell electrodes - II. Computational parameters, CHEMICAL ENGINEERING SCIENCE, Vol: 116, Pages: 781-792, ISSN: 0009-2509
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- Citations: 9
Yang W, Zhao Y, Liso V, et al., 2014, Optimal design and operation of a syngas-fuelled SOFC micro-CHP system for residential applications in different climate zones in China, ENERGY AND BUILDINGS, Vol: 80, Pages: 613-622, ISSN: 0378-7788
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- Citations: 28
Philbin SP, Jones D, Brandon NP, et al., 2014, Exploring Research Institutes: Structures, Functioning and Typology, Proceedings of PICMET'14 (Portland International Center for Management of Engineering and Technology) Conference, Kanazawa, Japan
Duboviks V, Maher RC, Kishimoto M, et al., 2014, A Raman spectroscopic study of the carbon deposition mechanism on Ni/CGO electrodes during CO/CO2 electrolysis, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 16, Pages: 13063-13068, ISSN: 1463-9076
Howey DA, Mitcheson PD, Yufit V, et al., 2014, Online measurement of battery impedance using motor controller excitation, IEEE Transactions on Vehicular Technology, Vol: 63, Pages: 2557-2566, ISSN: 0018-9545
This paper presents a fast cost-effective technique for the measurement of battery impedance online in an application such as an electric or hybrid vehicle. Impedance measurements on lithium-ion batteries between 1 Hz and 2 kHz give information about the electrochemical reactions within a cell, which relates to the state of charge (SOC), internal temperature, and state of health (SOH). We concentrate on the development of a measurement system for impedance that, for the first time, uses an excitation current generated by a motor controller. Using simple electronics to amplify and filter the voltage and current, we demonstrate accurate impedance measurements obtained with both multisine and noise excitation signals, achieving RMS magnitude measurement uncertainties between 1.9% and 5.8%, in comparison to a high-accuracy laboratory impedance analyzer. Achieving this requires calibration of the measurement circuits, including measurement of the inductance of the current sense resistor. A statistical correlation approach is used to extract the impedance information from the measured voltage and current signals in the presence of noise, allowing a wide range of excitation signals to be used. Finally, we also discuss the implementation challenges of an SOC estimation system based on impedance.
Ruiz-Trejo E, Boldrin P, Lubin A, et al., 2014, Novel Composite Cermet for Low-Metal-Content Oxygen Separation Membranes, Chemistry of Materials
Lomberg M, Ruiz-Trejo E, Offer G, et al., 2014, Characterization of Ni-Infiltrated GDC Electrodes for Solid Oxide Cell Applications, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 161, Pages: F899-F905, ISSN: 0013-4651
Maskell WC, Brett DJL, Brandon NP, 2014, Thick-film amperometric zirconia oxygen sensors: influence of cobalt oxide as a sintering aid, Publisher: IOP PUBLISHING LTD, ISSN: 0957-0233
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- Citations: 5
Tariq F, Yufit V, Eastwood DS, et al., 2014, In-Operando X-ray Tomography Study of Lithiation Induced Delamination of Si Based Anodes for Lithium-Ion Batteries, Electrochemistry Letters, Vol: 3
Silicon-Lithium based rechargeable batteries offer high gravimetric capacity. However cycle life and electrode microstructure failure mechanisms remain poorly understood. Here we present an X-ray tomography method to investigate in-operando lithiation induced stress cracking leading to the delamination of a composite Si based electrode. Simultaneous voltage measurements show increased cell resistance correlating with severe delamination and microstructural changes. 3D analysis revealed 44.1% loss of the initial electrode-current collector area after 1 hour of operation at 2.4 mA/cm2 and a 21.2% increase in new anode surface area. The work represents a new basis for future investigation of Si based anodes.
Wu B, Parkes MP, Yufit V, et al., 2014, Design and testing of a 9.5 kWe proton exchange membrane fuel cell-supercapacitor passive hybrid system, International Journal of Hydrogen Energy, Vol: 39, Pages: 7885-7896, ISSN: 0360-3199
The design and test of a 9.5 kWe proton exchange membrane fuel cell passively coupled with a 33 × 1500 F supercapacitor pack is presented. Experimental results showed that the system reduced dynamic loads on the fuel cell without the need for additional DC/DC converters. Fuel efficiency gains of approximately 5% were achieved by passive hybridisation in addition to addressing two main operational degradation mechanisms: no-load idling and rapid load cycling.Electrochemical Impedance Spectroscopy measurements indicated that the supercapacitor capacitance dropped with decreasing cell voltage and suggested that operation below 1.3 V is not recommended. Knee-frequency measurements suggested little benefit was gained in using passive systems with load cycles that have frequency components above 0.19 Hz. Analysis of system sizing suggested using the minimum number of supercapacitors to match the open circuit voltage of the fuel cell to maximise load buffering.
Chakrabarti MH, Brandon NP, Hajimolana SA, et al., 2014, Application of carbon materials in redox flow batteries, JOURNAL OF POWER SOURCES, Vol: 253, Pages: 150-166, ISSN: 0378-7753
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- Citations: 238
Eastwood DS, Bradley RS, Tariq F, et al., 2014, The application of phase contrast X-ray techniques for imaging Li-ion battery electrodes, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, Vol: 324, Pages: 118-123, ISSN: 0168-583X
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- Citations: 67
Eastwood DS, Yufit V, Gelb J, et al., 2014, Lithiation- Induced Dilation Mapping in a Lithium- Ion Battery Electrode by 3D X- Ray Microscopy and Digital Volume Correlation, ADVANCED ENERGY MATERIALS, Vol: 4, ISSN: 1614-6832
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- Citations: 84
Tariq F, Yufit V, Kishimoto M, et al., 2014, Three-dimensional high resolution X-ray imaging and quantification of lithium ion battery mesocarbon microbead anodes, JOURNAL OF POWER SOURCES, Vol: 248, Pages: 1014-1020, ISSN: 0378-7753
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- Citations: 65
Kishimoto M, Lomberg M, Ruiz-Trejo E, et al., 2014, Towards the microstructural optimisation of solid oxide fuel cell electrodes
One-dimensional numerical simulation and microstructural analysis of solid oxide fuel cell (SOFC) electrodes are carried out to investigate the effect of the characteristic length scale of the porous electrodes on the performance. The sensitivity of the current density is analysed over a wide range of triple-phase boundary (TPB) density and mean-pore size, which affect the electrochemical reaction and gas transport. Comparison between conventional electrodes and nano-particle infiltrated electrodes reveals that reducing characteristic length scale in the conventional electrodes helps improve the electrode performance by reducing the reaction resistance; however, introducing nano particles into the electrodes is expected to be more effective as it has a potential to increase the TPB density whilst keeping better gaseous transport through the electrodes. The three-dimensional microstructures of both types of electrodes are obtained with focused ion beam scanning electron microscopy and provide useful microstructural information that supports the numerical analysis.
Guerra C, Lanzini A, Leone P, et al., 2014, Optimization of dry reforming of methane over Ni/YSZ anodes for solid oxide fuel cells, JOURNAL OF POWER SOURCES, Vol: 245, Pages: 154-163, ISSN: 0378-7753
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- Citations: 48
Kishimoto M, Lomberg M, Ruiz-Trejo E, et al., 2014, Towards the microstructural optimisation of solid oxide fuel cell electrodes
One-dimensional numerical simulation and microstructural analysis of solid oxide fuel cell (SOFC) electrodes are carried out to investigate the effect of the characteristic length scale of the porous electrodes on the performance. The sensitivity of the current density is analysed over a wide range of triple-phase boundary (TPB) density and mean-pore size, which affect the electrochemical reaction and gas transport. Comparison between conventional electrodes and nano-particle infiltrated electrodes reveals that reducing characteristic length scale in the conventional electrodes helps improve the electrode performance by reducing the reaction resistance; however, introducing nano particles into the electrodes is expected to be more effective as it has a potential to increase the TPB density whilst keeping better gaseous transport through the electrodes. The three-dimensional microstructures of both types of electrodes are obtained with focused ion beam scanning electron microscopy and provide useful microstructural information that supports the numerical analysis.
Tariq F, Yufit V, Kishimoto M, et al., 2014, Advanced 3D Imaging and Analysis of SOFC Electrodes, Symposium on Solid State Ionic Devices 10 held during the 226th Meeting of the Electrochemical-Society, Publisher: ELECTROCHEMICAL SOC INC, Pages: 81-86, ISSN: 1938-5862
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- Citations: 2
Kishimoto M, Lomberg M, Ruiz-Trejo E, et al., 2014, Towards the Microstructural Optimization of SOFC Electrodes Using Nano Particle Infiltration, Symposium on Solid State Ionic Devices 10 held during the 226th Meeting of the Electrochemical-Society, Publisher: ELECTROCHEMICAL SOC INC, Pages: 93-102, ISSN: 1938-5862
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- Citations: 9
Chung D-W, Shearing PR, Brandon NP, et al., 2014, Particle Size Polydispersity in Li-Ion Batteries, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 161, Pages: A422-A430, ISSN: 0013-4651
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- Citations: 91
kucernak, brandon, yufit, 2013, regenerative fuel cells
The present invention provides a regenerative fuel cell comprising an anionic membrane capable of selectively passing anions, wherein the pH of the anolyte and/or catholyte is at least 10. The present invention also relates to a method of operating a regenerative fuel cell comprising an anionic membrane capable of selectively passing anions, wherein the pH of the anolyte and/or catholyte is at least 10.
Wu B, Yufit V, Marinescu M, et al., 2013, Coupled thermal–electrochemical modelling of uneven heat generation in lithium-ion battery packs, Journal of Power Sources, Vol: 243, Pages: 544-554, ISSN: 0378-7753
Abstract In battery packs with cells in parallel, the inter-cell connection resistances can cause unequal loads due to non-uniform interconnect overpotentials and consequentially lead to non-uniform heating. This article explores how load imbalances are generated in automotive applications, by describing a battery pack with finite interconnect resistances. Each cell inside the pack is represented by a pseudo 2D electrochemical model coupled with a lumped thermal model. Increasing the number of cells in parallel results in a linear increase in load non-uniformity, whilst increasing the ratio of interconnect to battery impedance results in a logarithmic increase in load non-uniformity, with cells closest to the load points experiencing the largest currents. Therefore, interconnect resistances of the order of mΩ can have a significant detrimental impact. Under steady state discharge the cell impedance changes until the loads balance. This process, however, can take hundreds of seconds and therefore may never happen under dynamic load cycles. Cycling within a narrow state-of-charge range and pulse loading are shown to be the most detrimental situations. Upon load removal, re-balancing can occur causing further heating. Simulation of a 12P7S pack under a real world load cycle shows that these effects could cause localised thermal runaway.
Chakrabarti MH, Brandon NP, Mjalli FS, et al., 2013, Cyclic Voltammetry of Metallic Acetylacetonate Salts in Quaternary Ammonium and Phosphonium Based Deep Eutectic Solvents, JOURNAL OF SOLUTION CHEMISTRY, Vol: 42, Pages: 2329-2341, ISSN: 0095-9782
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- Citations: 19
Lorente E, Berrueco C, Millan M, et al., 2013, Effect of tar fractions from coal gasification on nickel-yttria stabilized zirconia and nickel-gadolinium doped ceria solid oxide fuel cell anode materials, JOURNAL OF POWER SOURCES, Vol: 242, Pages: 824-831, ISSN: 0378-7753
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- Citations: 24
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.
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