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  • 1.
    Acevedo Gomez, Yasna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Reformate from biogas used as fuel in a PEM fuel cell2013Inngår i: EFC 2013 - Proceedings of the 5th European Fuel Cell Piero Lunghi Conference, 2013, s. 163-164Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The performance of a PEM fuel cell can be easily degraded by introducing impurities in the fuel gas. Since reformate of biogas from olive mill wastes will contain at least one third of carbon dioxide, its influence was studied on a PtRu catalyst. A clean reformate gas for the anode (67% H2 and 33% CO2) without any traces of other compounds was used and electrochemical measurements showed that the performance of the fuel cell was hardly affected. However, diluting the hydrogen with higher amounts of CO2 will reduce the performance remarkably.

  • 2.
    Benamira, M.
    et al.
    ENSCP, Paris.
    Albin, V.
    ENSCP, Paris.
    Ringuedé, A.
    ENSCP, Paris.
    Vannier, R-N.
    UMR 8181 CNRS.
    Bodén, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cassir, M.
    ENSCP, Paris.
    Structural and Electrical Properties of Gadolinia-doped Ceria Mixed with Alkali Earth Carbonates for SOFC Applications2007Inngår i: SOLID OXIDE FUEL CELLS 10 (SOFC-X), PTS 1 AND 2 / [ed] Eguchi, K; Singhai, SC; Yokokawa, H; Mizusaki, H, 2007, s. 2261-2268Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The properties of composite materials based on mixtures of gadolinium-doped ceria (GDC) and Li(2)CO(3)-K(2)CO(3) are analyzed as potential SOFC electrolytes. In a temperature range higher than 500 degrees C, their ionic conductivity is significantly higher than for single GDC. Discontinuities were found in the conductivity Arrhenius diagram (sigma vs. 1/T) around the melting point of the carbonate mixture (490 degrees C), showing, at least partially, the contribution of molten carbonates. At this stage, precise mechanisms are still under analysis.

  • 3. Benamira, M.
    et al.
    Ringuede, A.
    Albin, V.
    Vannier, R. -N
    Hildebrandt, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cassir, M.
    Gadolinia-doped ceria mixed with alkali carbonates for solid oxide fuel cell applications: I. A thermal, structural and morphological insight2011Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 196, nr 13, s. 5546-5554Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ceria-based composites are developed and considered as potential electrolytes for intermediate solid oxide fuel cell applications (ITSOFC). After giving a survey of the most relevant results in the literature, the structural, thermal and morphological properties of composite materials based on gadolinia-doped ceria (GDC) and alkali carbonates (Li2CO3-K2CO3 or Li2CO3-Na2CO3) are carefully examined. Thermal analyses demonstrate the stability of the composite with very low weight losses of both water and CO2 during thermal cycling and after 168 h ageing. High-temperature and room-temperature X-ray diffraction allowed determining the precise structure of the composite and its regular and reversible evolution with the temperature. The microstructure and morphology of electrolyte pellets, as observed by scanning electron microscopy (SEM), show two-well separated phases: nanocrystals of GDC and a well-distributed carbonate phase. Finally, electrical conductivity determined by impedance spectroscopy is presented as a function of time to highlight the stability of such composites over 1500h.

  • 4.
    Benamira, M.
    et al.
    Chimie ParisTech.
    Ringuede, A.
    Chimie ParisTech.
    Hildebrandt, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Vannier, R-N
    UMR 8181 CNRS.
    Cassir, M.
    Chimie ParisTech.
    Gadolinia-doped ceria mixed with alkali carbonates for SOFC applications: II - An electrochemical insight2012Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, nr 24, s. 19371-19379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Composite materials based on gadolinia-doped ceria (GDC) and alkali carbonates (Li2CO3-K2CO3 or Li2CO3-Na2CO3) are potential electrolytes for low temperature solid oxide fuel cell applications (LTSOFC). This paper completes a first one dedicated to the thermal, structural and morphological study of such compounds; it is fully focussed on their electrical/electrochemical properties in different conditions, temperature, composition and gaseous atmosphere (oxidative or reductive). The influence of the gaseous composition on the Arrhenius conductivity plots is evidenced, in particular under hydrogen atmosphere. Finally, electrical conductivity determined by impedance spectroscopy is presented as a function of time to highlight the stability of such composites over 6000 h. First results on single cells showed performance at 600 degrees C of 60 mW cm(-2).

  • 5. Benamira, M.
    et al.
    Ringuedé, A.
    Vannier, R. -N
    Hildebrandt, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Cassir, M.
    Behaviour of Gadolinia-doped ceria mixed with alkali carbonates in view of SOFC applications2009Inngår i: EFC 2009 - Piero Lunghi Conference, Proceedings of the 3rd European Fuel Cell Technology and Applications Conference, 2009, s. 197-198Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Composite materials based on mixtures of gadolinia-doped ceria and alkali carbonate salts were developed and analyzed for their use as electrolyte materials in low-temperature solid oxide fuel cells (LT-SOFCs). Cycling and ageing studies showed a good chemical stability of the composite material. A high and stable conductivity value (0,66 S.cm-1) was obtained all over a test of about 1600 hours at 600°C.

  • 6. Bergman, B.
    et al.
    Lagergren, Carina
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Schwartz, S.
    Zhu, B. H.
    Contact corrosion resistance between the cathode and current collector plate in the molten carbonate fuel cell2001Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, nr 1, s. A38-A43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The corrosion layer Formed in the contact between the cathode and the current collector is one factor limiting the cathode performance in molten carbonate fuel cells (MCFC). In order to investigate the contribution to the total polarization of the contact resistance, electrochemical experiments were performed in a laboratory-scale fuel cell unit with a specially designed current collector. Two cathode materials, NiO and LiCoO2, were investigated to elucidate the impact of the cathode material on the formed corrosion layer. Polarization measurements as well as electrochemical impedance spectroscopy were used. The method works well for NiO electrodes. However, due to the poor electronic conductivity in the LiCoO2 electrode, the experimental results become difficult to evaluate due to a nonuniform potential distribution. The contact resistance between the cathode and the current collector contributes with a large value to the total cathode polarization. The corrosion layer in case of the LiCoO2 cathode was iron-rich and has a thickness of about 20 mum after 8 weeks operation of the fuel cell. Ln the case of the NiO cathode, a nickel-rich corrosion layer of about 15 mum was formed after 5 weeks operation of the fuel cell.

  • 7.
    Bergman, Bill
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Schwartz, Stephan
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Zhu, Baohua
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Contact Corrosion Resistance Between the Cathode and the Current Collector Plate in the MCFC1999Inngår i: Carbonate Fuel Cell Technology V / [ed] I. Uchida, K.Hemmes, G. Lindbergh, D.A. Shores and J.R. Selman, 1999, s. 150-Konferansepaper (Fagfellevurdert)
  • 8.
    Bodén, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Di, Jing
    School of Chemical Engineering and Technology, Tianjin University, China.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Wang, Cheng Yang
    School of Chemical Engineering and Technology, Tianjin University, China.
    Conductivity of SDC and (Li/Na)2CO3 composite electrolytes in reducing and oxidising atmospheres2007Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 172, nr 2, s. 520-529Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Composite electrolytes made of samarium-doped cerium oxide and a mixture of lithium carbonate and sodium carbonate salts are investigated with respect to their structure, morphology and ionic conductivity. The composite electrolytes are considered promising for use in so called intermediate temperature solid oxide fuel cells (IT-SOFC), operating at 400-600 degrees C. The electrolytes are tested in both gaseous anode (reducing) and cathode (oxidising) environments and at different humidities and carbon dioxide partial pressures. For the structure and morphology measurements, it was concluded that no changes occur to the materials after usage. From measurements of melting energies, it was concluded that the melting point of the carbonate salt phase decreases with decreasing fraction of carbonate salt and that a partial melting occurs before the bulk melting point of the salt is reached. For all the composites, two regions may be observed for the conductivity, one below the carbonate salt melting point and one above the melting point. The conductivity is higher when electrolytes are tested in anode gas than when tested in cathode gas, at least for electrolytes with less than half the volume fraction consisting of carbonate salt. The higher the content of carbonate salt phase, the higher the conductivity of the composite for the temperature region above the carbonate melting point. Below the melting point, though, the conductivity does not follow this trend. Calculations on activation energies for the conductivity show no trend or value that indicates a certain transport mechanism for ion transport, either when changing between the different composites or between different gas environments.

  • 9.
    Carlson, Annika
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Ekström, Henrik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi. COMSOL.
    Grimler, Henrik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Tidigare Institutioner (före 2005), Kemiteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Tidigare Institutioner (före 2005), Kemiteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    An Electrochemical Impedance Study of the Hydrogen Electrode Reaction in the Anion Exchange Membrane Fuel CellManuskript (preprint) (Annet vitenskapelig)
  • 10.
    Carlson, Annika
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Eriksson, Björn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Olsson, Joel
    Lund University.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Jannasch, Patric
    Lund University.
    Wreland Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Fuel cell evaluation of anion exchange membranes based on PPO with different cation placementManuskript (preprint) (Annet vitenskapelig)
  • 11.
    Carlson, Annika
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Shapturenka, Pavel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Eriksson, Björn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Electrode parameters and operating conditions influencing the performance of anion exchange membrane fuel cells2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 277, s. 151-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A deeper understanding of porous electrode preparation and performance losses is necessary to advance the anion exchange membrane fuel cell (AEMFC) technology. This study has investigated the performance losses at 50 °C for varied: Tokuyama AS-4 ionomer content in the catalyst layer, Pt/C loading and catalyst layer thickness at the anode and cathode, relative humidity, and anode catalyst. The prepared gas diffusion electrodes in the interval of ionomer-to-Pt/C weight ratio of 0.4–0.8 or 29–44 wt% ionomer content show the highest performance. Varying the loading and catalyst layer thickness simultaneously shows that both the cathode and the anode influence the cell performance. The effects of the two electrodes are shown to vary with current density and this is assumed to be due to non-uniform current distribution throughout the electrodes. Further, lowering the relative humidity at the anode and cathode separately shows small performance losses for both electrodes that could be related to lowered ionomer conductivity. Continued studies are needed to optimize, and understand limitations of, each of the two electrodes to obtain improved cell performance.

  • 12.
    Carlson, Annika
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Shapturenka, Pavel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Porous electrode optimization in anion-exchange membrane fuel cells2015Inngår i: Proceedings of the 6th European Fuel Cell - Piero Lunghi Conference, EFC 2015, ENEA , 2015, s. 221-222Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The performance of anion-exchange membrane fuel cells is highly dependent on electrode preparation. This study has investigated the influence of water content and catalyst to ionomer ratio in the electrode ink on in-situ fuel cell performance and the electrode microstructure using SEM. It has shown that changing the solvent composition affects the electrode properties. Higher water content in ink results in a lower power density. An increase in water content from 40 to 70 vol% shows a 500 mA/cm2 drop in current density. SEM analysis of newly prepared electrodes revealed an observable difference in the microstructure. This indicates that for high water volume the ionomer distribution in the electrode is very uneven. The results also indicate that lower ionomer content in the bulk of the structure lowers the cell performance, which may be explained by limited hydroxide transportation.

  • 13. Cassir, Michel
    et al.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Basile, Angelo
    Strategic views on molten carbonates: An introduction to the special issue section on the "2015 International Workshop on Molten Carbonates & Related Topics (IWMC2015), 11-13 June, 2015, Shenyang, China"2016Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, nr 41, s. 18687-18691Artikkel i tidsskrift (Fagfellevurdert)
  • 14.
    Chiche, Ariel
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Stenius, Ivan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Sizing the energy system on long-range AUV2018Inngår i: AUV 2018 - 2018 IEEE/OES Autonomous Underwater Vehicle Workshop, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Autonomous Underwater Vehicles (AUVs) can be used for various types of unmanned missions. Currently, the most common energy storage technique is rechargeable batteries. In order to increase the range and endurance of these vehicles, where volume is a limiting factor, fuel cell systems could offer a very attractive solution. Fuel cell systems can have a drastically increased specific energy compared to batteries and are now starting to become well developed technologies. However, in an underwater environment, both hydrogen and oxygen needs to be stored for the fuel cell. This study presents a sizing tool that compares the weight and volume to balance fuel cell and battery energy storage solutions for some selected AUV missions. The main result is the shifting point between batteries and hybrid battery/fuel cell system in terms of volume efficiency, where longer missions favor the latter.

  • 15.
    Degerman Engfeldt, Johnny
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Georen, Peter
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, N Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Methodology for measuring current distribution effects in electrochromic smart windows2011Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 50, nr 29, s. 5639-5646Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochromic (EC) devices for use as smart windows have a large energy-saving potential when used in the construction and transport industries. When upscaling EC devices to window size, a well-known challenge is to design the EC device with a rapid and uniform switching between colored (charged) and bleached (discharged) states. A well-defined current distribution model, validated with experimental data, is a suitable tool for optimizing the electrical system design for rapid and uniform switching. This paper introduces a methodology, based on camera vision, for experimentally validating EC current distribution models. The key is the methodology's capability to both measure and simulate current distribution effects as transmittance distribution. This paper also includes simple models for coloring (charging) and bleaching (discharging), taking into account secondary current distribution with charge transfer resistance and ohmic effects. Some window-size model predictions are included to show the potential for using a validated EC current distribution model as a design tool.

  • 16.
    Degerman Engfeldt, Johnny
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Georen, Peter
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, N Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Predicting Performance of Large Area Electrochromic Smart WindowsArtikkel i tidsskrift (Annet vitenskapelig)
  • 17.
    Eriksson, Björn
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Jaouen, F.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Degradation and lifetime evaluation of Fe-N-C based catalyst in PEMFC2015Inngår i: Proceedings of the 6th European Fuel Cell - Piero Lunghi Conference, EFC 2015, ENEA , 2015, s. 223-224Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The restricted lifetime of Fe-N-C based catalysts is often assumed to be connected to the operating temperature. This study will investigate how the cell performance, electrode structure and composition vary over time, at different cell temperatures. At lower temperature, one may expect an increase in radical's stability, but a decrease in reactivity. Results show that the electrode degenerates over time, and that the electrochemical performance decay is similar for 40, 60, and 80° C. However, the loss of active sites is higher at higher temperature. This suggests that indirect production of radicals via H2O2 production during ORR is higher at higher temperatures and is a key degradation mechanism for this Fe-N-C catalyst.

  • 18.
    Eriksson, Björn
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Montserrat-Sisó, Gerard
    Chalmers University of Technology.
    Brown, Rosemary
    Chalmers University of Technology.
    Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Wickman, Björn
    Chalmers University of Technology.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Evaluation of rare earth metal alloy catalysts for the oxygen reduction reaction in proton exchange membrane fuel cellsManuskript (preprint) (Annet vitenskapelig)
  • 19.
    Fontes, Eduardo
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Lagergren, Carina
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Simonsson, Daniel
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Influence of gas phase mass transfer limitations on molten carbonate fuel cell cathodes1997Inngår i: Journal of Applied Electrochemistry, ISSN 0021-891X, E-ISSN 1572-8838, Vol. 27, nr 10, s. 1149-1156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this paper is to elucidate to what extent mass transfer limitations in the gas phase affect the performance of porous molten carbonate fuel cell cathodes. Experimental data from porous nickel oxide cathodes and calculated data are presented. One and two-dimensional models for the current collector and electrode region have been used. Shielding effects of the current collector are taken into account. The mass balance in the gas phase is taken into account by using the Stefan-Maxwell equation. For standard gas composition and normal operating current density, the effect of gas-phase diffusion is small. The diffusion in the gaseous phase must be considered at operation at higher current densities. For low oxygen partial pressures, the influence of mass transfer limitations is large, even at low current densities. To eliminate the influence of conversion on polarization curves recorded on laboratory cell units, measurements should always be performed with a five to tenfold stoichiometric excess of oxygen. Two-dimensional calculations show rather large concentration gradients in directions parallel to the current collector. However, the influence on electrode performance is still small, which is explained by the fact that most of the current is produced close to the electrolyte matrix.

  • 20.
    Fontes, Eduardo
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Lagergren, Carina
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Simonsson, Daniel
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Mathematical modelling of the MCFC cathode: On the linear polarisation of the NiO cathode1997Inngår i: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 432, nr 1-2, s. 121-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experimental polarisation curves for the porous lithiated NiO cathode used in molten carbonate fuel cells very often exhibit a linear shape over a wide potential range. It is shown by means of mathematical modelling that this linear behaviour can be explained by the interplay of intrinsic electrode kinetics, diffusion of electroactive species through an electrolyte film and the effective ohmic resistance of the pore electrolyte, providing that the cathodic transfer coefficient has a value of about 1.5. In contrast, with the generally assumed value of 0.5 of this transfer coefficient and with reasonable values of the effective electrolyte conductivity, predicted polarisation curves will always bend downwards over the overvoltage region of interest. The evolution of the polarisation curves with increasing electrolyte fill can be simulated by a model according to which the electroactive surface area becomes gradually blocked with the increasing amount of electrolyte.

  • 21.
    Fontes, Eduardo
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Lagergren, Carina
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Simonsson, Daniel
    KTH, Tidigare Institutioner                               , Kemiteknik.
    MATHEMATICAL-MODELING OF THE MCFC CATHODE1993Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 38, nr 18, s. 2669-2682Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Grimler, Henrik
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Carlson, Annika
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Ekström, Henrik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi. COMSOL.
    Lagergren, Carina
    KTH, Tidigare Institutioner (före 2005), Kemiteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Tidigare Institutioner (före 2005), Kemiteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Determination of kinetic parameters for the oxygen reduction reaction on platinum in an AEMFCManuskript (preprint) (Annet vitenskapelig)
  • 23.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Ekström, Henrik
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    A model for gas phase mass transport on the porous nickel electrode in the molten carbonate electrolysis cellManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    A one-dimensional model based on the Maxwell-Stefan diffusion equations was applied to evaluate the effect of the reverse water-gas shift reaction and the influence of the gas phase mass transport on the performance of the porous nickel electrode in the molten carbonate electrolysis cell. The concentration gradients in the current collector are larger than in the electrode for the inlet gases not in equilibrium, due to the shift reaction taking place in the electrode. When the humidified gas compositions enter the current collector, the decrease of the shift reaction rate increases the electrode performance. The model well describes the polarization behavior of the Ni electrode in the electrolysis cell when the inlet gases have low contents of hydrogen. The mass-transfer limitations at low contents of water and carbon dioxide are captured in the model, but the effect on the electrode polarization, especially of carbon dioxide, is overestimated. Despite an overestimation in the calculations, the experimental data and the modeling results are still consistent in that carbon dioxide has a stronger effect on the gas phase mass transport than other components, i.e. water and hydrogen.

  • 24.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Electrode Kinetics of the Ni Porous Electrode for Hydrogen Production in a Molten Carbonate Electrolysis Cell (MCEC)2015Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 162, nr 9, s. F1020-F1028Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to elucidate the kinetics of a porous nickel electrode for hydrogen production in a molten carbonate electrolysis cell. Stationary polarization data for the Ni electrode were recorded under varying gas compositions and temperatures. The slopes of these iR-corrected polarization curves were analyzed at low overpotential, under the assumption that the porous electrode was under kinetic control with mass-transfer limitations thus neglected. The exchange current densities were calculated numerically by using a simplified porous electrode model. Within the temperature range of 600-650 degrees C, the reaction order of hydrogen is not constant; the value was found to be 0.49-0.44 at lower H-2 concentration, while increasing to 0.79-0.94 when containing 25-50% H-2. The dependence on CO2 partial pressure increased from 0.62 to 0.86 with temperature. The reaction order of water showed two cases as did hydrogen. For lower H2O content (10-30%), the value was in the range of 0.47-0.67 at 600-650 degrees C, while increasing to 0.83-1.07 with 30-50% H2O. The experimentally obtained partial pressure dependencies were high, and therefore not in agreement with any of the mechanisms suggested for hydrogen production in molten carbonate salts in this study.

  • 25.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Electrode kinetics of the NiO porous electrode for oxygen production in the molten carbonate electrolysis cell (MCEC)2015Inngår i: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 182, s. 493-509Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of a molten carbonate electrolysis cell (MCEC) is to a great extent determined by the anode, i.e. the oxygen production reaction at the porous NiO electrode. In this study, stationary polarization curves for the NiO electrode were measured under varying gas compositions and temperatures. The exchange current densities were calculated numerically from the slopes at low overpotential. Positive dependency on the exchange current density was found for the partial pressure of oxygen. When the temperature was increased in the range 600-650 degrees C, the reaction order of oxygen decreased from 0.97 to 0.80. However, there are two different cases for the partial pressure dependency of carbon dioxide within this temperature range: positive values, 0.09-0.30, for the reaction order at lower CO2 concentration, and negative values, -0.26-0.01, with increasing CO2 content. A comparison of theoretically obtained data indicates that the oxygen-producing reaction in MCEC could be reasonably satisfied by the reverse of oxygen reduction by the oxygen mechanism I, an n = 4 electron reaction, assuming a low coverage of oxide ions at high CO2 content and an intermediate coverage for a low CO2 concentration.

  • 26.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Operating the nickel electrode with hydrogen-lean gases in the molten carbonate electrolysis cell (MCEC)2016Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, nr 41, s. 18692-18698Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    If a molten carbonate electrolysis cell (MCEC) is applied for fuel gas production it is important to know the polarization of the nickel electrode when operated at low concentration of hydrogen. Thus, the electrochemical performance of the Ni electrode was investigated under hydrogen-lean gases containing 1/24.5/24.5/50%, 1/49.5/24.5/25%, 1/24.5/49.5/25% and 1/49.5/49.5/0% H-2/CO2/H2O/N-2 in the temperature range of 600-650 degrees C and was then compared to the reference case with 25/25/25/25% H-2/CO2/H2O/N-2. The electrochemical measurements included polarization curve coupled with current interrupt, and electrochemical impedance spectroscopy. Polarization resistances of the Ni electrode obtained by the two different techniques agreed well. For the inlet gases containing low amounts of hydrogen the Ni electrode exhibited higher polarization losses than when using the reference case in the electrolysis cell. The electrochemical impedance measurements showed that both charge-transfer and mass-transfer polarizations were higher for hydrogen-lean gases at all measured temperatures. Except under the condition with 1/49.5/49.5% H-2/CO2/H2O at 650 degrees C, the Ni electrode exhibited lower mass-transfer polarization when compared to the reference case. Furthermore, the mass-transfer polarization was strongly dependent on temperature under H-2-lean gases, differing from the reference case when the temperature has almost no effect on mass-transfer polarization. The activation energy for hydrogen production was calculated to be in the range of 69 -138 kJ mol(-1) under all measured gases, indicating that the Ni electrode is under kinetic and/or mixed control in the MCEC.

  • 27.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Operating the nickel electrode with hydrogen-lean gases in the molten carbonate electrolysis cell (MCEC)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    If a molten carbonate electrolysis cell (MCEC) is applied for fuel gas production it is important to know the polarization of the nickel electrode when operated at low concentration of hydrogen. Thus, the electrochemical performance of the Ni electrode was investigated under hydrogen-lean gases containing 1/24.5/24.5/50%, 1/49.5/24.5/25%, 1/24.5/49.5/25% and 1/49.5/49.5/0% H2/CO2/H2O/N2 in the temperature range of 600–650 °C and was then compared to the reference case with 25/25/25/25% H2/CO2/H2O/N2. The electrochemical measurements included polarization curve coupled with current interrupt, and electrochemical impedance spectroscopy. Polarization resistances of the Ni electrode obtained by the two different techniques agreed well. For the inlet gases containing low amounts of hydrogen the Ni electrode exhibited higher polarization losses than when using the reference case in the electrolysis cell. The electrochemical impedance measurements showed that both charge-transfer and mass-transfer polarizations were higher for hydrogen-lean gases at all measured temperatures. Except under the condition with 1/49.5/49.5% H2/CO2/H2O at 650 °C, the Ni electrode exhibited lower mass-transfer polarization when compared to the reference case. Furthermore, the mass-transfer polarization was strongly dependent on temperature under H2-lean gases, differing from the reference case when the temperature has almost no effect on mass-transfer polarization. The activation energy for hydrogen production was calculated to be in the range of 69–138 kJ·mol-1 under all measured gases, indicating that the Ni electrode is under kinetic and/or mixed control in the MCEC.

  • 28.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Performance and Durability of the Molten Carbonate Electrolysis Cell and the Reversible Molten Carbonate Fuel Cell2016Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 25, s. 13427-13433Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The molten carbonate electrolysis cell (MCEC) provides the opportunity for producing fuel gases, e.g., hydrogen or syngas, in an environmentally friendly way, especially when in combination with renewable electricity resources such as solar, wind, and/or hydropower. The evaluation of the performance and durability of the molten carbonate cell is a key for developing the electrolysis technology. In this study, we report that the electrochemical performance of the cell and electrodes somewhat decreases during the long-term test of the MCEC. The degradation is not permanent, though, and the cell performance could be partially recovered. Since conventional fuel cell materials consisting of nickel-based porous catalysts and carbonate electrolyte are used in the MCEC durability test, it is also shown that the cell can alternatingly operate as an electrolysis cell for fuel gas production and as a fuel cell for electricity generation, i.e., as a so-called reversible molten carbonate fuel cell (RMCFC). This study reveals that the cell performance improves after a long period of RMCFC operation. The stability and durability of the cell in long-term tests evidence the feasibility of the electrolysis and reversible operations in carbonate melts using a conventional fuel cell setup, at least in lab scale.

  • 29.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Performance and durability of the molten carbonate electrolysis cell (MCEC) and the reversible molten carbonate fuel cell (RMCFC)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The molten carbonate electrolysis cell (MCEC) provides the opportunity for producing fuel gases, e.g. hydrogen or syngas, in an environmentally friendly way, especially when in combination with renewable electricity resources such as solar, wind and/or hydropower. The evaluation of the performance and durability of the molten carbonate cell is a key for developing the electrolysis technology. In this study, we report that the electrochemical performance of the cell and electrodes somewhat decreases during the long-term test of the MCEC. The degradation is not permanent, though, and the cell performance could be partially recovered. Since conventional fuel cell materials consisting of Ni-based porous catalysts and carbonate electrolyte are used in the MCEC durability test, it is also shown that the cell can alternatingly operate as an electrolysis cell for fuel gas production and as a fuel cell for electricity generation, i.e. as a so-called reversible molten carbonate fuel cell (RMCFC). This study reveals that the cell performance improves after a long period of RMCFC operation. The stability and durability of the cell in long-term tests evidence the feasibility of the electrolysis and reversible operations in carbonate melts using a conventional fuel cell set-up, at least in lab-scale.

  • 30.
    Hu, Lan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Rexed, Ivan
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Electrochemical performance of reversible molten carbonate fuel cells2014Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, nr 23, s. 12323-12329Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electrochemical performance of a state-of-the-art molten carbonate cell was investigated in both fuel cell (MCFC) and electrolysis cell (MCEC) modes by using polarization curves and electrochemical impedance spectroscopy (EIS). The results show that it is feasible to run a reversible molten carbonate fuel cell and that the cell actually exhibits lower polarization in the MCEC mode, at least for the short-term tests undertaken in this study. The Ni hydrogen electrode and the NiO oxygen electrode were also studied in fuel cell and electrolysis cell modes under different operating conditions, including temperatures and gas compositions. The polarization of the Ni hydrogen electrode turned out to be slightly higher in the electrolysis cell mode than in the fuel cell mode at all operating temperatures and water contents. This was probably due to the slightly larger mass-transfer polarization rather than to charge-transfer polarization according to the impedance results. The CO2 content has an important effect on the Ni electrode in electrolysis cell mode. Increasing the CO2 content the Ni electrode exhibits slightly lower polarization in the electrolysis cell mode. The NiO oxygen electrode shows lower polarization loss in the electrolysis cell mode than in the fuel cell mode in the temperature range of 600-675 degrees C. The impedance showed that both charge-transfer and mass-transfer polarization of the NiO electrode are lower in the electrolysis cell than in the fuel cell mode.

  • 31.
    Kortsdottir, Katrin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Pérez Ferriz, Francisco Javier
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Reformate Hydrogen Fuel in PEM Fuel Cells: the Effect of Alkene Impurities on Anode Activity2013Inngår i: ECS Transactions, Electrochemical Society, 2013, s. 1857-1865Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Reformate hydrogen contains many impurities, some are well known while others have been less studied. Hydrocarbons are possible impurities in reformate hydrogen and are among those less studied. This study if aimed at alkenes, with special focus on propene. Adsorption and desorption on the Pt catalyst is studied using stripping cyclic voltammetry combined with mass spectrometry. The results show that although the effect of propene in the presence of hydrogen is expected to be minimal, adsorption and blockage of catalytic sites cannot be ruled out. A small amount of ad-species is formed on Pt at low adsorption potentials, and in the presence of hydrogen, although suppression of the hydrogen desorption peak was minimal if hydrogen was adsorbed on the Pt catalyst prior to exposure.

  • 32.
    Lagergren, Carina
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Electrochemical performance of porous MCFC cathodes1997Doktoravhandling, med artikler (Annet vitenskapelig)
  • 33.
    Lagergren, Carina
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Experimental determination of effective conductivities in porous molten carbonate fuel cell electrodes1998Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 44, nr 2-3, s. 503-511Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work an electrochemical impedance spectroscopy method fbr the determination of the effective conductivities of the pore electrolyte and electrode matrix in porous electrodes has been used. The technique has been employed on porous nickel oxide and lithium cobaltite cathodes partly flooded with lithium-potassium carbonate melt in cathode gas environment. The experimental results show that the effective conductivity of the pore electrolyte of a porous nickel oxide cathode is 0.9-2.2 Omega(-1) m(-1) at the most. If data are approximately corrected for the faradaic reaction the effective conductivity becomes 0.1-0.7 Omega(-1) m(-1). For the lithium cobaltite cathode the measured conductivity of the solid phase is similar to the data measured ex-situ. The effective conductivity of the pore electrolyte is 0.8 Omega(-1) m(-1), i.e. close to the results found for nickel oxide cathodes. The effective conductivity of the pore electrolyte calculated by means of a theoretical model is 0.5-3.5 Omega(-1) m(-1).

  • 34.
    Lagergren, Carina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Teknikbevakning av stationära smältkarbonatbränsleceller 20092009Rapport (Annet vitenskapelig)
  • 35.
    Lagergren, Carina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Teknikbevakning av stationära smältkarbonatbränsleceller (MCFC) 20082009Rapport (Annet (populærvitenskap, debatt, mm))
  • 36.
    Lagergren, Carina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Teknikbevakning av stationära smältkarbonatbränsleceller (MCFC) 2010-20112011Rapport (Annet vitenskapelig)
  • 37.
    LAGERGREN, CARINA
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    LINDBERGH, GÖRAN
    KTH, Tidigare Institutioner                               , Kemiteknik.
    SIMONSSON, DANIEL
    KTH, Tidigare Institutioner                               , Kemiteknik.
    INVESTIGATION OF POROUS ELECTRODES BY CURRENT INTERRUPTION APPLICATION TO MOLTEN CARBONATE FUEL CELL CATHODES1995Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 142, nr 3, s. 787-797Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A transient agglomerate model for simulation and analysis of experimental data, obtained by current interruption on porous molten carbonate fuel cell cathodes, is presented. The initial fast change of the potential after current interruption on a polarized NiO electrode is due to the closed-circuit potential distribution in the electrode. Conventional estimation of the iR corrected overvoltage by current interruption on porous electrodes, with finite electronic conductivity in the solid phase and a finite ionic conductivity of the pore electrolyte, leads to an overcompensation of the external potential drop and an underestimation of the total steady-state overvoltage due to the internal currents passing in the electrode after interruption. The overcompensation of the external potential drop is directly proportional to the geometric current density and to the thickness of the electrode and inversely proportional to the sum df the effective conductivities in the electrode matrix and the pore electrolyte.

  • 38.
    LAGERGREN, CARINA
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    LUNDBLAD, ANDERS
    KTH, Tidigare Institutioner                               , Kemiteknik.
    BERGMAN, BILL
    KTH, Tidigare Institutioner                               , Kemiteknik.
    SYNTHESIS AND PERFORMANCE OF LICOO2 CATHODES FOR THE MOLTEN CARBONATE FUEL CELL1994Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 141, nr 11, s. 2959-2966Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for fabricating LiCoO2 electrodes has been developed. LiCoO2 powder was synthesized from Li2CO3 and CoCO3 powder by calcining in air at 650-degrees-C. Electrodes were tape cast in a nonaqueous slurry with and without a graphite poreformer. They were sintered in air at temperatures between 700 and 850-degrees-C. Powders and electrodes were characterized by using x-ray diffraction, thermogravimetric analysis, the Brunauer, Emmett, and Teller method, Hg porosimetry, scanning electron microscopy, and a van der Pauw conductivity measurement setup. The electrodes were electrochemically characterized by polarization measurements at different temperatures. Performance of the electrodes, with and without poreformer, respectively, was also determined by measuring polarization curves at different degrees of electrolyte fill.

  • 39.
    Lagergren, Carina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Simonsson, Daniel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    The effects of oxidant gas composition on the polarization of porous LiCoO2 electrodes for MCFC1997Inngår i: Carbonate Fuel Cell Technology IV / [ed] J. R. Selman, I. Uchida, H. Wendt, D. A. Shores and T. F. Fuller, 1997, s. 329-Konferansepaper (Annet vitenskapelig)
  • 40.
    Lagergren, Carina
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Simonsson, Daniel
    KTH, Tidigare Institutioner                               , Kemiteknik.
    The effects of oxidant gas composition on the polarization of porous LiCoO2 electrodes for the molten carbonate fuel cell1997Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 144, nr 11, s. 3813-3818Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stationary polarization curves were obtained for porous lithium cobaltite cathodes under varying temperatures and oxidant compositions. The exchange current densities were determined from the slope at low overpotentials by means of numerical calculations, taking into account the current density distribution. Positive influences on the exchange current density were found both for the partial pressure of oxygen and carbon dioxide. The results are similar to earlier data obtained from measurements on NiO electrodes. The values are not consistent with either the peroxide mechanism or the superoxide mechanism, two mechanisms often proposed in the literature.

  • 41.
    Lindahl, Niklas
    et al.
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden..
    Eriksson, Björn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Groenbeck, Henrik
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden..
    Wreland Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Wickman, Bjoern
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden..
    Fuel Cell Measurements with Cathode Catalysts of Sputtered Pt3Y Thin Films2018Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, nr 9, s. 1438-1445Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fuel cells are foreseen to have an important role in sustainable energy systems, provided that catalysts with higher activity and stability are developed. In this study, highly active sputtered thin films of platinum alloyed with yttrium (Pt3Y) are deposited on commercial gas diffusion layers and their performance in a proton exchange membrane fuel cell is measured. After acid pretreatment, the alloy is found to have up to 2.5 times higher specific activity than pure platinum. The performance of Pt3Y is much higher than that of pure Pt, even if all of the alloying element was leached out from parts of the thin metal film on the porous support. This indicates that an even higher performance is expected if the structure of the Pt3Y catalyst or the support could be further improved. The results show that platinum alloyed with rare earth metals can be used as highly active cathode catalyst materials, and significantly reduce the amount of platinum needed, in real fuel cells.

  • 42. Mesfun, S.
    et al.
    Lundgren, J.
    Toffolo, A.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Engvall, Klas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Integration of an electrolysis unit for producer gas conditioning in a bio-synthetic natural gas plant2019Inngår i: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 141, nr 1, artikkel-id 012002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Producer gas from biomass gasification contains impurities like tars, particles, alkali salts, and sulfur/nitrogen compounds. As a result, a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into synthetic natural gas (SNG). A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of syngas produced. Internal rate of return (IRR) is evaluated as an economic indicator of the processes considered. Results indicate that, depending on process configuration, the production of SNG can be boosted by approximately 50-60% without the need of an additional carbon source, i.e., for the same biomass input as in standalone operation of the GoBi-Gas plant.

  • 43. Mesfun, Sennai
    et al.
    Lundgren, Joakim
    Toffolo, Andrea
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Engvall, Klas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Integration of an electrolysis unit for producer gas conditioning in a bio-SNG plant2017Inngår i: 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2017, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Producer gas from biomass gasification contains impurities like tars, particles, alkali salts and sulfur/nitrogen compounds. As a result a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into SNG. A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of tailored syngas produced. Investment opportunity is evaluated as an economic indicator of the processes considered. Results indicate that the production of SNG can be boosted by approximately 50% without the need of an additional carbon source, i.e. for the same biomass input as in standalone operation of the GoBiGas plant.

  • 44.
    Oyarce, Alejandro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Gonzalez, Carlos
    Lima, Raquel Bohn
    Wreland Lindström, Rakel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Direct sorbitol proton exchange membrane fuel cell using moderate catalyst loadings2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 116, s. 379-387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent progress in biomass hydrolysis has made it interesting to study the use of sorbitol for electricity generation. In this study, sorbitol and glucose are used as fuels in proton exchange membrane fuel cells having 0.9 mg cm(-2) PtRu/C at the anode and 0.3 mg cm(-2) Pt/C at the cathode. The sorbitol oxidation was found to have slower kinetics than glucose oxidation. However, at low temperatures the direct sorbitol fuel cell shows higher performance than the direct glucose fuel cell, attributed to a lower degree of catalyst poisoning. The performance of both fuel cells is considerably improved at higher temperatures. High temperatures lower the poisoning, allowing the direct glucose fuel cell to reach a higher performance than the direct sorbitol fuel cell. The mass specific peak power densities of the direct sorbitol and direct glucose fuel cells at 65 degrees C was 3.2 mW Mg-catalyst(-1) and 3.5 mW Mg-catalyst(-1), respectively. Both of these values are one order of magnitude larger than mass specific peak power densities of earlier reported direct glucose fuel cells using proton exchange membranes. Furthermore, both the fuel cells showed a considerably decrease in performance with time, which is partially attributed to sorbitol and glucose crossover poisoning the Pt/C cathode.

  • 45.
    Oyarce, Alejandro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Holmström, Nicklas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Bodén, A.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Operating conditions affecting the contact resistance of bi-polar plates in proton exchange membrane fuel cells2013Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 231, s. 246-255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Both ex-situ and in-situ measurements of contact resistance between gas diffusion layer (GDL) and bi-polar plate (BPP) were carried out using the same fuel cell hardware. Each BPP sample was submitted to ex-situ testing at room temperature, ex-situ testing in simulated fuel cell environment and in-situ testing, isolating the effect of specific operating conditions on the contact resistance. Increasing cell temperatures and relative humidity (RH) of the gases lowered the contact resistance. However, the presence of liquid water, measured as an increase in pressure drop over the cathode, affected the contact resistance negatively. High current density operation raises the temperature of the cell, but simultaneously increases the water content at the cathode, causing an increase of the contact resistance. In the case of uncoated steel 316L and gold-coated steel 316L, high current density operation for an extended period of time also caused a progressive deterioration of the contact resistance, which without this in-situ measurement could have been mistaken for other ohmic losses, e.g. increased membrane resistance due to metal ion poisoning.

  • 46.
    Oyarce, Alejandro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Hussami, Linda L.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Corkey, Robert W.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Polyhedral Carbon Nanoforms as catalyst support in a Proton Exchange Membrance cathodeManuskript (preprint) (Annet vitenskapelig)
  • 47.
    Oyarce, Alejandro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    The Electrochemical Response of a Corroded PEMFC Cathode: Mass-transport at low RHManuskript (preprint) (Annet vitenskapelig)
  • 48.
    Oyarce, Alejandro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Zakrisson, Erik
    Ivity, Matthew
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Baumann Ofstad, Axel
    Bodén, Andreas
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Comparing shut-down strategies for proton exchange membrane fuel cells2014Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 254, s. 232-240Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Application of system strategies for mitigating carbon corrosion of the catalyst support in proton exchange fuel cells (PEMFCs) is a requirement for PEMFC systems, especially in the case of systems for transport application undergoing thousands of start-ups and shut-downs (SU/SD) during its lifetime. This study compares several of the most common shut-down strategies for 1100 cycles SU/SD cycles at 70 C and 80% RH using commercially available fuel cell components. Each cycle simulates a prolonged shut-down, i.e. finishing each cycle with air filled anode and cathode. Furthermore, all start-ups are unprotected, i.e. introducing the H2 rich gas into an air filled anode. Finally, each cycle also includes normal fuel cell operation at 0.5 A cm-2 using synthetic reformate/air. H2 purge of the cathode and O2 consumption using a load were found to be the most effective strategies. The degradation rate using the H2 purge strategy was 23 μV cycle-1 at 0.86 A cm-2 using H 2 and air at the anode and cathode, respectively. This degradation rate may be regarded as a generally low value, especially considering that this value also includes the degradation rate caused by unprotected start-ups.

  • 49. Pettersson, Dan
    et al.
    Gustavsson, Marie
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    An experimental system for evaluation of well-defined catalysts on nonporous electrodes in realistic DMFC environment2006Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 51, nr 28, s. 6584-6591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports on an experimental setup wich enables us to investigate planar model catalysts in an environment closely resembling the environment found in an actual direct methanol fuel cell. The working electrodes were nano-structured catalyst particles immobilised on planar supports, reducing many of the commonly present non-catalyst related effects in conventional porous electrodes. Colloidal lithography was used for nano-structuring the samples. Nation was used as electrolyte. Results are presented for the oxidation of methanol, formaldehyde, formic acid and carbon monoxide at temperatures between 30 and 70 degrees C on Pt particles supported on glassy carbon disks.

  • 50. Pietra, M. D.
    et al.
    Rexed, Ivan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    McPhail, S.
    Paoletti, C.
    Moreno, A.
    Experimental procedures for accelerated aging tests using MCFC button cells2013Inngår i: EFC 2013 - Proceedings of the 5th European Fuel Cell Piero Lunghi Conference, 2013, s. 363-364Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this work is to study whether the effects of electrolyte evaporation in long term operation of MCFCs can be accelerated at button cell level due to the increased rate of evaporation in the open-chamber configuration. This study is being carried out with several trials: the first trial aims to generate a benchmark of performance at button cell level, i.e. with accelerated electrolyte evaporation, at reference operating conditions, carrying out regular polarization curves and EIS until the performance degrades below a predefined level. The second trial aims to compensate the evaporation of electrolyte from the button cell by periodically adding carbonate and maintain a constant performance for the length of time that the first button cell (without carbonate addition) achieved. Once the isolated effect of electrolyte evaporation has been thus quantified, successive trials can be set up to superimpose other degradation and evaluate their interaction with the mechanism of electrolyte evaporation.

12 1 - 50 of 82
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