415 results found
Mazur C, Contestabile M, Offer GJ, et al., 2015, Assessing and comparing German and UK transition policies for electric mobility, ENVIRONMENTAL INNOVATION AND SOCIETAL TRANSITIONS, Vol: 14, Pages: 84-100, ISSN: 2210-4224
Ruiz-Trejo E, Boldrin P, Medley-Hallam JL, et al., 2015, Partial oxidation of methane using silver/gadolinia-doped ceria composite membranes, Chemical Engineering Science, Vol: 127, Pages: 269-275, ISSN: 1873-4405
Methane was partially oxidised to CO using oxygen permeated through a 1 mm thick silver/Ce0.9Gd0.1O2−x (Ag/CGO) composite membrane operating at 500–700 °C with air at 1 bar pressure. The membranes were fabricated by sintering ultrafine nanoparticles of gadolinia-doped ceria (<5 nm) coated with silver using Tollens׳ reaction. This unique combination led to dense composites with low content of silver (7 vol%), no reaction between the components and predominant metallic conductivity. When feeding 4% methane at 700 °C to a 1-mm thick Ag/CGO using Ni as reforming catalyst, the conversion reached 21% and the CO selectivity 92% with an estimated oxygen flux of 0.18 mL min−1 cm−2 (NTP). The samples were stable in carbon-containing atmospheres and under a large pO2 transmembrane pressure difference at temperatures below 700 °C for 48 h.
Ruiz-Trejo E, Atkinson A, Brandon NP, 2015, Metallizing porous scaffolds as an alternative fabrication method for solid oxide fuel cell anodes, Journal of Power Sources, Vol: 280, Pages: 81-89, ISSN: 1873-2755
A combination of electroless and electrolytic techniques is used to incorporate nickel into a porous Ce0.9Gd0.1O1.90 scaffold. First a porous backbone was screen printed into a YSZ electrolyte using an ink that contains sacrificial pore formers. Once sintered, the scaffold was coated with silver using Tollens' reaction followed by electrodeposition of nickel in a Watts bath. At high temperatures the silver forms droplets enabling direct contact between the gadolinia-doped ceria and nickel. Using impedance spectroscopy analysis in a symmetrical cell a total area specific resistance of 1 Ωcm2 at 700 °C in 97% H2 with 3% H2O was found, indicating the potential of this fabrication method for scaling up.
Somalu MR, Muchtar A, Brandon NP, 2015, Understanding the rheology of screen-printing inks for the fabrication of SOFC thick films, Pages: 1323-1331, ISSN: 1938-5862
© The Electrochemical Society. Fabrication of SOFC components by screen-printing using an optimized ink is very significant for the production of high quality films with improved performance. Understanding the correlation between the composition and rheology of the inks may enhance the properties screen-printed films. In this study, the rheological properties of NiO/ScSZ anode inks were studied and correlated to the particle network strength, screen-printability and film properties. All the inks were fabricated using a triple roll mill. The dynamic study showed that inks having particle network strength and complex modulus in the range of 50-200 Pa and 500-4000 Pa, respectively, were determined suitable for screen-printing application. In addition, these inks showed suitable viscosity and thixotropy with acceptable tackiness for screen-printing application. This range was exhibited by inks having binder and solids loading in the range of 1-3 wt% and 25-30 vol%, respectively. Furthermore, films fabricated using these inks showed improved particle connectivity, mechanical hardness, electrical and electrochemical performance resulting from increased particle connectivity.
Wu B, Yufit V, Merla Y, et al., 2015, Differential thermal voltammetry for tracking of degradation in lithium-ion batteries, Journal of Power Sources, Vol: 273, Pages: 495-501, ISSN: 1873-2755
Monitoring of lithium-ion batteries is of critical importance in electric vehicle applications in order to manage the operational condition of the cells. Measurements on a vehicle often involve current, voltage and temperature which enable in-situ diagnostic techniques. This paper presents a novel diagnostic technique, termed differential thermal voltammetry, which is capable of monitoring the state of the battery using voltage and temperature measurements in galvanostatic operating modes. This tracks battery degradation through phase transitions, and the resulting entropic heat, occurring in the electrodes. Experiments to monitor battery degradation using the new technique are compared with a pseudo-2D cell model. Results show that the differential thermal voltammetry technique provides information comparable to that of slow rate cyclic voltammetry at shorter timescale and with load conditions easier to replicate in a vehicle.
Boldrin P, Millan-Agorio M, Brandon NP, 2015, Effect of Sulfur- and Tar-Contaminated Syngas on Solid Oxide Fuel Cell Anode Materials, ENERGY & FUELS, Vol: 29, Pages: 442-446, ISSN: 0887-0624
Boldrin P, Ruiz-Trejo E, Yu J, et al., 2015, Nanoparticle scaffolds for syngas-fed solid oxide fuel cells, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 3, Pages: 3011-3018, ISSN: 2050-7488
Cooper SJ, Li T, Bradley RS, et al., 2015, Multi length-scale quantification of hierarchical microstructure in designed microtubular SOFC electrodes, Pages: 1857-1864, ISSN: 1938-5862
© The Electrochemical Society. The transport properties of a micro-tubular solid oxide fuel cell (MT-SOFC) anode have been analysed by imaging and simulation at multiple length-scales. The anode support investigated was manufactured using a phase inversion-assisted co-extrusion process, which generated a hierarchical and highly anisotropic microstructure. The resulting pore network was observed to contain two distinct, but interacting transport systems. The features in these systems spanned several orders of magnitude and as such it was not possible to image or model them simultaneously. The simulations indicated that the design of the microstructure was beneficial for the radial transport required by these cells; however this conclusion was only obtained by considering diffusive systems at many length-scales.
Tariq F, Kishimoto M, Cui G, et al., 2015, Advanced 3D imaging and analysis of SOFC electrodes, Pages: 2067-2074, ISSN: 1938-5862
© The Electrochemical Society. An ability to meet our increasing energy demands will be facilitated though improving the next generation of electrochemical devices. The ability to directly image in 3D and analyse solid oxide fuel cell (SOFC) electrodes at high resolutions provides key insights in understanding structure-property relationships; as electrochemical reactions and transport phenomena are strongly affected by complex microstructure. Here we use tomographic techniques to probe 3D electrode structures at nanometer to micrometer length scales. In doing so the first characterisation of specific necks and interfaces alongside their particle sizes within SOFC electrodes is derived. Micro/nano structural changes are followed to facilitate understanding the differences which occur with shape, structures and morphology at high resolution. These are correlated with both measured experimental values and simulations to provide insight into microstructure-property relationships. We also demonstrate approaches to intelligently design electrodes through scaffolds, and potentially 3D printed structures, all towards optimising the structure for performance.
Kishimoto M, Lomberg M, Ruiz-Trejo E, et al., 2015, Towards the design-led optimization of solid oxide fuel cell electrodes, Pages: 2019-2028, ISSN: 1938-5862
© The Electrochemical Society. A one-dimensional numerical model of a nickel-infiltrated gadolinium-doped ceria (Ni-GDC) electrode has been developed to investigate the effects of electrode microstructure on performance. Electrode microstructural information was obtained with focused-ion beam tomography and microstructural parameters were quantified. These have been used to estimate the effective transport coefficients and the electrochemical reaction rate in the electrode. GDC was considered as a mixed ionic and electronic conductor and hence the electrochemical reaction was assumed to occur on the GDC-pore contact surface, i.e. double-phase boundaries (DPBs). Sensitivity analysis was conducted to investigate the effect of electrode microstructure on both transport properties and electrochemical activity. The developed model offers a basis to understand the electrode-microstructure relationships and to further optimize the electrode microstructures.
Cai Q, Adjiman CS, Brandon NP, 2014, Optimal control strategies for hydrogen production when coupling solid oxide electrolysers with intermittent renewable energies, JOURNAL OF POWER SOURCES, Vol: 268, Pages: 212-224, ISSN: 0378-7753
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
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
Howey DA, Yufit V, Mitcheson PD, et al., 2014, Impedance measurement for advanced battery management systems
© 2013 IEEE. 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
© 2013 IEEE. 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
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
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
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
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.
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
Kalyvas C, Kucernak A, Brett D, et al., 2014, 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
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
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.
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
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
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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