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Samantilleke A.P.,University of Minho | Cerqueira M.F.,University of Minho | Heavens S.,Ionotec Ltd. | Warren P.,Pilkington Group Ltd | And 4 more authors.
Thin Solid Films | Year: 2011

Aqueous electrolyte contacts have been used to characterize CdS thin films grown using chemical bath deposition (CBD) on 4 different fluorine-doped tin oxide (FTO) coated conducting glass substrates (identified by the supplier Pilkington Group Limited as TEC-15, TEC-7, NSG low-E, and NSG Solar). The porosity of CdS layers prepared on different substrates was evaluated by voltammetry using the oxidation of hexacyanoferrate (II) to probe residual electrochemical activity arising from the underlying conducting substrate. Using a simple model, it can be concluded that thin films deposited on NSG substrates at 85 °C are probably nanoporous with a porosity of up to ∼ 20% of the coverage of the CdS surface. The porosity appears to depend on the nature of the substrate rather than the physical parameters of the deposition. In the case of non-porous films deposited on TEC substrates, analysis of the impedance gave values of the space charge capacitance from which the doping density and flat band potential were derived. The doping densities for CdS were found to be in the order of 1017 cm-3-1020 cm-3 depending on the substrate. The transmission spectra, recorded in the UV-visible range, reveal a relatively high transmission coefficient in the obtained films. The transmittance data further indicate that the optical band gap is closely related to the deposition conditions. Micro-Raman analysis showed structural similarity and differences between porous and non-porous thin films. © 2011 Elsevier B.V.


Min J.K.,Pusan National University | Stackpool M.,IONOTEC Ltd. | Shin C.H.,Defense Agency for Technology and Quality | Lee C.-H.,Korea Advanced Institute of Science and Technology
Journal of Power Sources | Year: 2015

Abstract A numerical prediction model is developed for the safety analysis of molten sodium-sulfur battery. Under the assumption that a crack occurred in a solid electrolyte of a cell, a rapid increase in the temperature and pressure from a direct reaction between sulfur and sodium can be predicted by solving equations for flow, energy and the chemical reaction. The crack, the powder-type in-filler and the carbon felt in the sulfur electrode are modeled by porous media approximations. The results are compared to experimental results with extreme value probability statistics for the data assessment. The effects of the size of the cell and wick tube, the depth of discharge, and the filler material are summarized quantitatively. © 2015 Elsevier B.V.


Muftah G.E.A.,Sheffield Hallam University | Samantilleke A.P.,Sheffield Hallam University | Warren P.D.,Pilkington European Technology Center | Heavens S.N.,Ionotec Ltd. | Dharmadasa I.M.,Sheffield Hallam University
Journal of Materials Science: Materials in Electronics | Year: 2010

Copper indium ditelluride (CuInTe 2) has been electrochemically deposited from aqueous solution. Cyclic voltammetry analyses were used to determine suitable deposition parameters. As measured by Tallysurf and gravimetric techniques, the thickness of films deposited over a period of 3 h was found to be ~1.5 μm. X-ray diffraction, optical absorption and scanning electron microscopy have been used to investigate the bulk structure, energy bandgap and surface morphology of the material layers respectively. It was found that the material layers have polycrystalline chalcopyrite structure and bandgaps varied between 1.05 and 1.30 eV. Current-voltage characteristics of the CuInTe 2/electrolyte, solid/liquid junctions were measured under dark and illuminated conditions. The layers were found to be photo active and p-type in electrical conduction. © 2009 Springer Science+Business Media, LLC.


Lu X.,University College London | Evans J.R.G.,University College London | Heavens S.N.,Ionotec Ltd.
Journal of the European Ceramic Society | Year: 2012

This work concerns the manufacture of planar cell configurations for molten sodium batteries in energy storage devices such as vehicle batteries and stationary storage cells. Tape casting of beta-alumina electrolyte could provide a low-cost mass production route but intriguingly there are only a few reports of tape casting using beta-alumina directly as the raw powder. We first compared tape casting of α-alumina and beta-alumina using polyvinyl butyral (PVB) in conventional formulations. While it is relatively easy to obtain homogeneous α-alumina tape cast sheet, beta-alumina resulted in adhesion to the substrate and cracking. These problems were shown to be attributable to particle characteristics. When the binder was changed to polymethylmethacrylate (PMMA), tape casting of beta-alumina and three different α-alumina powders was facilitated, producing a formulation that was more tolerant to different powder types. Screening of several commercial dispersants provided two which were effective with PMMA and a conventional MEK/ethanol dual solvent. © 2012 Elsevier Ltd.


Lu X.,University College London | Evans J.R.G.,University College London | Heavens S.N.,Ionotec Ltd.
Journal of the European Ceramic Society | Year: 2012

Tape casting is a low cost fabrication process for flat ceramic sheet and this paper demonstrates how it can be combined with vacuum forming to make α-alumina domes of 250-300 μm sintered thickness. The suspension formulation makes use of systems of double plasticizers and double solvents in a poly(methyl methacrylate) binder to provide plastic ceramic films by tape casting from which preforms for vacuum forming were cut. In order to retain the shape of vacuum formed domes during debinding and sintering, an initial low temperature anneal is needed. The study indicates that the ratio of plasticizers to binder and the particle size are two dominant parameters in influencing the elongational flow. The whole process provides a novel method to make thin ceramic domes. © 2011 Elsevier Ltd.


Patent
IONOTEC Ltd | Date: 2014-01-27

An electrochemical cell comprises a cathodic reactant, an anodic region containing liquid sodium, and a solid electrolyte separating the cathodic reactant from the liquid sodium in the anodic region. The anodic region is contained within the solid electrolyte. The cell further comprises a separate reservoir of liquid sodium the anodic region being supplied with liquid sodium from the reservoir. A metal plug is provided in the anodic region. The reservoir is not contained within the solid electrolyte.

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