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  • 1.
    Araujo, Rafael B.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Scheicher, Ralph H.
    de Almeida, J. S.
    Ferreira da Silva, A.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    First-principles investigation of Li ion diffusion in Li2FeSiO42013Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 247, s. 8-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have studied the Li-ion migration and the electrochemical performance of Li2FeSiO4 in the monoclinic crystal structure with P2(1) symmetry and the related delithiated system LiFeSiO4. For this purpose, the framework of the density functional theory within the generalized gradient approximation in conjunction with the climbing image nudged elastic band method was used. Addition of the Hubbard term was also considered in the Kohn-Sham Hamiltonian to better model the d electrons of the metal ions in this material. The calculated activation energies for Li ion migration are found to decrease by around 20% with the Hubbard term inclusion in the chosen diffusion pathways of Li2FeSiO4. Regarding the delithiated structure, the activation energies were found to be sensitive to the Hubbard term addition, however no general behavior such as in the lithiated structure was found. Furthermore, the diffusion coefficients were calculated considering temperatures of 300 K, 500 K, and 700 K.

  • 2. Ekstrom, Henrik
    et al.
    Lafitte, Benoit
    Ihonen, Jari
    Markusson, Henrik
    Jacobsson, Per
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Jannasch, Patric
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Evaluation of a sulfophenylated polysulfone membrane in a fuel cell at 60 to 110 degrees C2007Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 178, nr 13-14, s. 959-966Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel sulfophenylated polysulfone membrane material has been evaluated in a hydrogen/oxygen fuel cell using Nation-impregnated commercial electrodes. Comparative measurements were performed with Nation membranes to distinguish between different sources of potential losses. The operational temperatures in the experiments ranged from 60 to 110 degrees C, and the effect of different humidifying conditions was investigated. Membranes that were operated over 300 h under fully humidified conditions showed a slight increase in the cell resistance. At lower humidification levels the cell resistance increased significantly. No difference in the membrane composition between active areas and areas not subjected to ionic currents could be detected by ATR-IR or Raman spectroscopy after fuel cell testing. The best fuel cell performance for these membranes was found at 90 degrees C and 100 degrees C. The current density at a cell voltage of 0.5 V ranged between 100 and 200 mA cm(-2) depending on the operating conditions. The relatively low current densities found when using the new membrane material are explained by high ionic contact resistances between the electrodes and the membrane.

  • 3.
    Gode, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Hult, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Jannasch, Patric
    Polymer Science and Engineering, Lund University.
    Johansson, M.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Lina E.
    Polymer Science and Engineering, Lund University.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Sandquist, D.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    A novel sulfonated dendritic polymer as the acidic component in proton conducting membranes2006Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 177, nr 7-8, s. 787-794Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study involves the synthesis of sulfonated poly(3-ethyl-3-(hydroxymethyl)oxetane), sPTMPO, by end-capping the hydroxy-groups in the PTMPO with 1,4-butane sultone. A series of the polymer with different degrees of substitution was investigated. Furthermore, the subsequent use of the sulfonated PTMPO as the acidic component in proton conducting membranes was explored. The membranes were prepared by either a) mixing the partly sulfonated PTMPO with hexamethoxymethyl melamine (HMMM) to form cross-links by ether formation between the methylol groups on HMMM and the remaining hydroxyl groups on the hyperbranched polyether or b) using the sulfonated polyether in conjunction with a pyridine functionalised polysulfone, PSU-pyridine, to produce acid-base blend membranes. Membrane properties such as proton conductivity, water uptake and mechanical properties are discussed.

  • 4. Gotte, A.
    et al.
    Spangberg, D.
    Hermansson, Kersti
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Baudin, M.
    Molecular dynamics study of oxygen self-diffusion in reduced CeO22007Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 178, nr 25-26, s. 1421-1427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxygen self-diffusion in partially reduced CeO2 has been investigated by large-scale Molecular Dynamics simulations, in the temperature range between 800 and 2200 K. Simulation boxes with similar to 4100 and similar to 33,000 ions were investigated for randomly distributed oxygen vacancies and Ce3+ ions. Our calculated self-diffusion coefficients vary between 10(-8) and 10(-6) cm(2)/s in the temperature range studied. The activation energy and D-0 values are also reported. The oxygen diffusion mechanism has also been analyzed: only a (< 100 > vacancy mechanism is observed.

  • 5. Hallström, Samuel
    et al.
    Halvarsson, Mats
    Höglund, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Jonsson, Torbjorn
    Ågren, John
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    High temperature oxidation of chromium: Kinetic modeling and microstructural investigation2013Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 240, s. 41-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using CALPHAD methods, Cr2O3 growth on pure Cr is modeled using DICTRA and the vacancy model for diffusion. The results are compared with thermobalance and TEM experiments at 625 and 700 degrees C in O-2. The experimental scatter is significant, leading to a compromise suggestion. With the experimental conditions from the furnace exposures in this work, optimized mobilities are validated with a series of oxidation simulations. Despite the complex microstructure and initial growth rate variations, it is possible to reproduce the experimental oxide thicknesses with good accuracy, allowing for extension to multicomponent systems.

  • 6. Kaewmaraya, T.
    et al.
    Ramzan, M.
    Osorio-Guillen, J. M.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University.
    Electronic structure and ionic diffusion of green battery cathode material: Mg2Mo6S82014Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 261, s. 17-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report ab-initio density functional theory calculations of crystal and electronic structure of Mg2Mo6S8, a candidate material to be used in rechargeable magnesium batteries, by employing hybrid exchange-correlation functionals. We find that Mg2Mo6S8 crystalizes in a triclinic geometry and it is a semiconductor with an indirect band gap. Ab-initio molecular dynamics shows that Mg ions present progressive diffusion starting at 200 K with a preferable path through the channel between Mo6S8 blocks along the [010] direction. The intercalation voltage of the system is also determined and the results show that the voltage evaluated by PBE and hybrid functionals likely implies the lower and the upper limit of the experimental value. Lastly, we confirm the dynamical stability of the crystal structure by the calculated phonon dispersion relation.

  • 7. Klarbring, Johan
    et al.
    Vekilova, Olga Yu
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Uppsala University, Sweden.
    Nilsson, Johan O.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Skorodumova, Natalia V.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Uppsala University, Sweden.
    Simak, Sergei I.
    Ionic conductivity in Sm-doped ceria from first-principles non-equilibrium molecular dynamics2016Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 296, s. 47-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sm-doped ceria is a prospective electrolyte material for intermediate-temperature solid-oxide fuel cells (IT-SOFC). Equi- librium ab initio molecular dynamics (AIMD) studies of oxygen ion diffusion in this material are currently impractical due to the rareness of diffusive events on the accessible timescale. To overcome this issue we have performed ab ini- tio non-equilibrium molecular dynamics calculations of Sm-doped ceria using the color-diffusion algorithm. Applying an external force field we have been able to increase the frequency of diffusive events over the simulation time, while keeping the physical mechanism of diffusion intact. We have investigated the temperature dependence of the maximum strength of the applied external field that could be used while maintaining the response of the system in a linear regime. This allows one to obtain the diffusivity at zero field. The bulk ionic conductivity has been calculated and found to match the experimental data well. We have also compared the description of the diffusion process by our method to previous findings and show that the migration mechanism and site preference of oxygen vacancies with respect to the Sm dopants is well reproduced. 

  • 8. Landa, A. I.
    et al.
    Chang, C. C.
    Kumta, P. N.
    Vitos, Levente
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Abrikosov, I. A.
    Phase stability of Li(Mn100-xCox)O-2 oxides: an ab initio study2002Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 149, nr 04-mar, s. 209-215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The full charge density exact muffin-tin orbitals method has been used to study the stability of lithium manganese oxides exhibiting different crystallographic forms. Calculations have been performed in various crystallographic phases of LiMnO2 for the ferromagnetic and antiferromagnetic spin configurations on Mn sublattice, as well as for the state with local moment disorder. For the ordered LiMnO2 compound, the experimentally observed antiferromagnetic orthorhombic ground state structure was reproduced. The effect of doping of the Mn sites by Co was considered with the primary aim to predict the stabilization of the layered structure.

  • 9.
    Li, Shuai
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Bergman, Bill
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Zhao, Zhe
    Preparation and characterisation of perovskite La0.8Sr0.2Ga0.83Mg0.17O2.815 electrolyte using a poly(vinyl alcohol) polymeric methodIngår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689Artikel i tidskrift (Övrigt vetenskapligt)
  • 10. Murugesan, S.
    et al.
    Wijayasinghe, A.
    Bergman, Bill
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Preparation and characterization of CuI-doped silver borovanadate superionic system2007Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 178, nr 11-12, s. 779-783Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new cost effective glassy/crystalline superionic system xCul-(100-x)[2Ag(2)O-0.7V(2)O(5)-0.3B(2)O(3)], where x=30, 40, 45, 50 and 60, has been prepared by melt quenching technique and the ionic transport properties were studied. The phase analysis and thermal properties of the samples carried out using XRD, FTIR and DSC techniques confirmed the glassy-crystalline composite nature of the prepared materials. DSC analyses indicated the crystallization of some phases between 130 and 170 degrees C and the subsequent melting of these crystallized phases in the temperature range of 200-250 degrees C. The room temperature electrical conductivity studies were carried out by a.c. impedance analysis. High room temperature electrical conductivity of 3.58 x 10(-3) S cm(-1) was obtained for the best conducting composition. These materials show high t(Ag+) value of 0.997. The use of two glass formers helped to form materials with higher T, higher thermal stability and better ionic transport properties.

  • 11. Osorio-Guillen, J. M.
    et al.
    Holm, B.
    Ahuja, Rajeev
    Johansson, Börje
    KTH, Tidigare Institutioner, Materialvetenskap.
    A theoretical study of olivine LiMPO4 cathodes2004Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 167, nr 3-4, s. 221-227Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on a density functional theory (DFT) calculation of the properties of LiMPO4, where M is either Fe, Mn or Co. The mixing between Fe and Mn in these structures is also examined. We have derived three relevant battery properties, namely average voltage, energy density and specific energy, as well as the lattice constants and ionic coordinates for each case examined. Our calculated values for these properties are in good agreement with recent experimental values, when available. Further insight is gained from the electronic density of states of the phases, through which conclusions about the physical properties of the various phases are made.

  • 12.
    Qian, Zhao
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Jiang, Xue
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    De Sarkar, Abir
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Adit Maark, Tuhina
    Deshpande, Mrinalini
    Bououdina, Mohamed
    Johansson, Börje
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Screening study of light-metal and transition-metal-doped NiTiH hydrides as Li-ion battery anode materials2014Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 258, s. 88-91Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Here we have investigated systematically the effects of various light-metals (Mg, Al) and transition-metals (V, Cr, Mn, Fe, Co, Cu, Zn) on the electrochemical properties of NiTiH hydrides as anodes for Li-ion battery applications. Based on the pristine NiTiH, a screening study in terms of the structure volume, average voltage and specific capacity has been performed to choose the most proper metal dopants. The most thermodynamically stable doping sites (Ni or Ti site) of various dopant metals have been determined respectively. It is finally summarized that in this study, the light metal Al or the transition metals Cr, Mn and Fe have the most comprehensive effects and are the most promising metal dopants for the pristine NiTiH hydride. This theoretical study is proposed to help understand the properties of the material and guide the design and development of more efficient metal-hydrides materials for Li-ion battery anode applications.

  • 13.
    Raza, Rizwan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Abbas, Ghazanfar
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Ma, Ying
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Electrochemical study of the composite electrolyte based on samaria-doped ceria and containing yttria as a second phase2011Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 188, nr 1, s. 58-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this study is to develop new oxide ionic conductors based on nanocomposite materials for an advanced fuel cell (NANOCOFC) approach. The novel two phase nanocomposite oxide ionic conductors, Ce0.8Sm0.2O2-delta (SDC)-Y2O3 were synthesized by a co-precipitation method. The structure and morphology of the prepared electrolyte were investigated by means of X-ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). XRD results showed a two phase composite consisting of yttrium oxide and samaria doped ceria and SEM results exhibited a nanostructure form of the sample. The yttrium oxide was used on the SDC as a second phase. The interface between two constituent phases and the ionic conductivities were studied with electrochemical impedance spectroscopy (EIS). An electrochemical study showed high oxide ion mobility and conductivity of the Y2O3-SDC two phase nanocomposite electrolytes at a low temperature (300-600 degrees C). Maximum conductivity (about 1.0 S cm(-1)) was obtained for the optimized Y2O3-SDC composite electrolyte at 600 degrees C. It is found that the nanocomposite electrolytes show higher conductivities with the increased concentration of yttrium oxides but decreases after reaching a certain level. A high fuel cell performance, 0.75 W cm(-2), was achieved at 580 degrees C.

  • 14. Samarasingha, Pushpaka B.
    et al.
    Wijayasinghe, Athula
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Dissanayake, Lakshman
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Development of cathode materials for lithium ion rechargeable batteries based on the system Li(Ni1/3Mn1/3Co(1/3-x)Mx)O-2, (M = Mg, Fe, Al and x=0.00 to 0.33)2014Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 268, s. 226-230Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study was based on developing Li(Ni1/3Mn1/3Co(1/3-x)Mx)O-2, (M = Mg, Fe, Al and x = 0 to 0.33) materials by substituting expensive Co content in this NMC system with cheaper Mg, Fe and Al additives for the cathode application in rechargeable lithium ion batteries (LIB). The Pechini method, which is a low-cost wet chemical technique, was used for powder synthesis in this study. The XRD phase analysis revealed the formation of solid solutions of appropriate layered Li(Ni1/3Mn1/3Co(1/3-x)Mx)O-2 phase.of R-3m structure in the prepared compositions over x = 0.11 substitution of Fe and Mg. Furthermore, these Fe and Mg substituted compositions showed considerably higher electrical conductivity than the base material Li(Ni1/3Mn1/3Co(1/3-x)Mx)O-2 (over 0.9 x 10(-5) S/cm at 25 degrees C). In the cell studies, the Fe and Mg substituted compositions with x = 0.11 showed a specific capacity of 122 and 125 mAhg(-1), respectively, which are comparable to the specific capacity of the state-of-the-art LiCoO2 cathode material of LIB. Altogether, this study shows the ability of preparing these NMC materials by Pechini method with appropriate structural and electrochemical properties suitable for the LIB cathode.

  • 15. van Wuellen, Leo
    et al.
    Sofina, N.
    Hildebrandt, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Muehle, Claus
    Jansen, M.
    NMR studies of cation transport in the crystalline ion conductors MCF3SO3 (M = Li, Na) and Li7TaO62006Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 177, nr 19-25, s. 1665-1672Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this contribution we present studies on the mechanism of ion transport in crystalline solid electrolytes employing a range of different solid state nuclear magnetic resonance (NMR) experiments. The first part is devoted to the elucidation of a possible correlation of cation transport and anion reorientation in the dynamically disordered rotor phases of alkali trifluoromethane sulfonates MCF3SO3 (M = Li, Na) employing Li-7, C-13, O-17 and Na-23 NMR line shape analysis, whereas the second part focuses on the tracking of cation diffusion pathways in the hexaoxometalate Li7TaO6 utilizing Li-6 1D and 2D exchange MAS NMR approaches.

  • 16. van Wullen, L.
    et al.
    Hildebrandt, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Jansen, M.
    Cation mobility and anion reorientation in lithium trifluoromethane sulfonate, LiCF3SO32005Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 176, nr 15-16, s. 1449-1456Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a detailed study of the dynamic processes present in the lithium ionic conductor lithium trifluoromethane sulfonate, LiCF3SO3. Using Li-7-, O-17- and F-19 solid state NMR line shape analysis and T-1-NMR, the anionic (CF3- and SO3-reorientation) and cationic dynamics (Li motion) could be studied separately. Whereas the CF3- and SO3 reorientations are active at ambient temperatures and not correlated to the cation motion, the NMR data indicate a strong correlation between the Li motion and the reorientation of the complete triflate anion.

  • 17. Wijayasinghe, A.
    et al.
    Bergman, Bill
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    LiFeO2-LiCoO2-NiO materials for Molten Carbonate Fuel Cell cathodes. Part I: Powder synthesis and material characterization2006Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 177, nr 1-2, s. 165-173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ternary compositions of LiFeO2LiCoO2 and NiO are expected to posses desirable characteristics for the Molten Carbonate Fuel Cell (MCFC) cathode application. This paper presents a detailed description of the synthesis of LiFeO2-LiCoO2-NiO powders as well as dense sintered materials together with a brief discussion on the common aspects and trends observed in the characterization of these materials for MCFC cathode application. Feasibility of two wet-chemical powder preparation techniques, the Pechini method and the glycine-nitrate method, was investigated to obtain powders with characteristics appropriate for cathode fabrication. Materials in the LiFeO2-NiO binary system and five ternary subsystems, each with a constant molar ratio of LiFeO2/NiO while varying LiCoO2 content, were studied. Powders with characteristics appropriate for MCFC cathode fabrication could be obtained by the Pechini method. The particle size of LiFeO2-LiCoO2-NiO powders considerably depends on the calcination temperature and the material composition. The electrical conductivity study reveals the ability of preparing LiFeO2-LiCoO2-NiO materials with adequate electrical conductivity for MCFC cathode application.

  • 18. Wijayasinghe, A.
    et al.
    Bergman, Bill
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    LiFeO2-LiCoO2-NiO materials for Molten Carbonate Fuel Cell cathodes. Part II. Fabrication and characterization of porous gas diffusion cathodes2006Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 177, nr 1-2, s. 175-184Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    LiFeO2-LiCoO2-NiO ternary materials are considered as more viable alternatives to lithiated NiO2 in solving the cathode dissolution problem of the Molten Carbonate Fuel Cell (MCFC). This paper presents a detailed description of fabrication and characterization of LiFeO2-LiCoO2-NiO porous gas diffusion cathodes for MCFC, together with a brief discussion on the limitations and trends observed in cathode optimization. Several LiFeO2-LiCoO2-NiO ternary compositions and a LiFeO2-NiO binary composition, were fabricated into porous cathodes by tape casting and sintering. The sintered cathodes were subjected to phase analysis, electrical conductivity and pore structural characterization. A bimodal pore structure, appropriate for the MCFC cathode, could be achieved in sintered cathodes prepared using poreformers and sub-micron size powders. The amount of poreformers significantly influences the pore structure and the electrical conductivity of sintered cathodes. Furthermore, this study indicates the nature of the compromise to be made between the electrical conductivity, phase purity, pore structure and porosity in optimization cathodes for the MCFC application.

  • 19.
    Willgert, Markus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Hellqvist Kjell, Maria
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    New structural lithium battery electrolytes using thiol-ene chemistry2013Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 236, s. 22-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of solid poly(ethylene oxide)-methacrylate lithium ion electrolytes containing thio-ether segments have successfully been produced and evaluated with respect to mechanical and electrical performance. The series have been varied in crosslink density and thio-ether content. The study presents thiol-ene compounds as yet another tool to design multifunctional electrolytes, and that they are compatible with and usable for polymer electrolyte systems. The electrolytes, produced in a solvent free process where the oligomers are active diluents of the lithium salt, express a broad range of both mechanical as well as ion conducting properties. Conductivity values presented ranges up to about 8 x 10(-7) S/cm, and a wide spectrum of values of the storage modulus is presented in a range from 2 MPa to 2 GPa at 20 degrees C. The influence of the crosslink density of the poly(ethylene oxide)-methacrylates with and without thio-ether segments is discussed. In order to present correlations between crosslink density and how the lithium ion transport is affected by incorporating multifunctional thiol monomers, density measurements have been undertaken to calculate the average molar mass between the crosslinks.

  • 20.
    Zhao, Zhe
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Öijerholm, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Microstructure and electrical conductivity of yttria stabilized zirconia ceramics sintered by spark plasma sintering: Part I. 3Y-TZPIngår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689Artikel i tidskrift (Övrigt vetenskapligt)
  • 21.
    Zhu, Bin
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Proton and oxygen ion-mixed-conducting ceramic composites and fuel cells2001Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 145, nr 04-jan, s. 371-380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work focuses on the behaviour and role of protons and oxygen ions for the electrical properties of salt-oxide composites based on halides, more specifically on fluorides e.g. MFx (M = Li, Na. Ca, Ba, Sr, Mg. x = 1, 2)-based composites with oxides. The electrical properties were studied by using DC measurements, employing either gas concentration cell or fuel cell techniques. The conductivity of the fluoride-based composite electrolytes is 10(-3)-10(-2) S/cm at temperatures between 600 and 800 degreesC. Proton and oxygen ion defects, their generation and transport, showed a very strong dependence on the employed gas resources. Possessing both proton and oxygen ion conduction, on one hand, enhances the material total conductivity and, on the other hand, may promote the electrode reaction and the kinetics at two interfaces between the electrolyte and electrodes for fuel cells, thus, enhancing the cur-rent exchange rate and fuel cell performance. Using these composite electrolytes, a typical power density of 120-160 mW/cm(2) under a current density 300-800 mA/cm(2) was obtained in a fuel cell. Although both proton and oxygen ion conduction are possible, the proton defect concentration and related conduction generally predominate as the basic feature of the halide-based composite materials.

  • 22.
    Zhu, Bin
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Albinsson, I.
    Mellander, B. E.
    Intermediate temperature fuel cells using alkaline and alkaline earth fluoride-based electrolytes2000Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 135, nr 04-jan, s. 503-512Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Investigation of fuel cell applications using fluoride electrolytes, especially alkaline and alkaline earth fluorides, is a very new subject. Actually, most of the fluorides can function as fuel cell electrolytes, but the alkaline and alkaline earth fluorides are specially interesting since in composite materials they exhibit excellent performance for fuel cell electrolytes. Among the alkaline earth fluoride fuel cells, the best performance was achieved thus far for the fuel cell using the NaF-BaF2-Al2O3 electrolyte and LiNiO2 anode supported technique: it reached a power density of about 110 mW cm(-2) at a current density of 250 mA cm(-2) at 750 degreesC. Both proton and oxygen ionic conduction may exist in the alkaline earth fluorides since, during the fuel cell operation, water was observed at both the anode and the cathode, but, in most cases, water was formed at the cathode side mainly. Thus, proton conduction predominates, resulting in excellent fuel cell performances. A possible ionic transport mechanism is also discussed.

  • 23.
    Zhu, Bin
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Fu, Q. X.
    Meng, G. Y.
    Jurado, J. F.
    Albinsson, I.
    Mellander, B. E.
    LiF-MgF2 composite electrolyte for advanced ceramic fuel cells: structure, electrical properties and applications2002Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 148, nr 04-mar, s. 583-589Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The two-phase composite, LiF-MgF2, has been discovered to have high ionic conductivity within a wide composition range, e.g., 10(-2)-10(-1) S cm(-1) at 600-800 degreesC, which is several orders of magnitude higher than that of pure LiF or MgF2. In addition, the activation energy of the composite is much lower than that of the pure phases. The remarkable conductivity enhancement as well as the low activation energy is attributed to the composite effect, i.e., the conduction takes place mainly in the interfacial region between LiF and MgF2 grains. The agreements of conductivity derived from two different methods, impedance spectra and fuel cell characterisation, in combination of the ESR results, show a possibility that proton (plus hydride ion) conduction dominates the electrical conduction in the LiF-MgF2 system under the H-2/air fuel cell environments.

  • 24.
    Zhu, Bin
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Tao, S. W.
    Chemical stability study of Li2SO4 in a H2S/O-2 fuel cell2000Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 127, nr 02-jan, s. 83-88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although H-2/O-2 fuel cells using Li2SO4 as the electrolyte have encountered problems in their chemical instability, the Li2SO4 electrolyte shows an excellent chemical stability under the operation conditions of a fuel cell using H2S as the fuel. Both thermodynamic analysis and experiments have demonstrated that it is feasible to develope practical H2S/O-2 fuel cells and co-generation devices based on the Li2SO4 electrolyte.

1 - 24 av 24
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