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  • 1. Benavente Araoz, Fabian Andres
    et al.
    Varini, Maria
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lundblad, Anders
    Saul, Cabrera
    Lindbergh, Göran
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Effect of partial cycling of NCA/graphite 1 cylindrical cells in different SOC intervalsManuscript (preprint) (Other academic)
  • 2.
    Benavente-Araoz, Fabian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Campana, P. E.
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Cabrera, S.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Loss-of-load probability analysis for optimization of small off-grid PV-battery systems in Bolivia2017In: Proceedings of the 9th International Conference on Applied Energy, Elsevier, 2017, Vol. 142, p. 3715-3720Conference paper (Refereed)
    Abstract [en]

    This study evaluates the use of energy storage technologies coupled to renewable energy sources in rural electrification as a way to address the energy access challenge. Characteristic energy demanding applications will differently affect the operating conditions for off-grid renewable energy systems. This paper discusses and evaluates simulated photovoltaic power output and battery state of charge profiles, using estimated climate data and electricity load profiles for the Altiplanic highland location of Patacamaya in Bolivia to determine the loss of load probability as optimization parameter. Simulations are performed for three rural applications: household, school, and health center. Increase in battery size prevents risk of electricity blackouts while increasing the energy reliability of the system. Moreover, increase of PV module size leads to energy excess conditions for the system reducing its efficiency. The results obtained here are important for the application of off-grid PV-battery systems design in rural electrification projects, as an efficient and reliable source of electricity.

  • 3. Campana, Pietro Elia
    et al.
    Quan, Steven Jige
    Robbio, Federico Ignacio
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Ma, Tao
    Karlssona, Bjorn
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Optimization of a residential district with special consideration on energy and water reliability2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 194, p. 751-764Article in journal (Refereed)
    Abstract [en]

    Many cities around the world have reached a critical situation when it comes to energy and water supply, threatening the urban sustainable development. From an engineering and architecture perspective it is mandatory to design cities taking into account energy and water issues to achieve high living and sustainability standards. The aim of this paper is to develop an optimization model for the planning of residential urban districts with special consideration of renewables and water harvesting integration. The optimization model is multi-objective which uses a genetic algorithm to minimize the system life cycle costs, and maximize renewables and water harvesting reliability through dynamic simulations. The developed model can be used for spatial optimization design of new urban districts. It can also be employed for analyzing the performances of existing urban districts under an energy-water-economic viewpoint. The optimization results show that the reliability of the hybrid renewables based power system can vary between 40 and 95% depending on the scenarios considered regarding the built environment area and on the cases concerning the overall electric load. The levelized cost of electricity vary between 0.096 and 0.212 $/kW h. The maximum water harvesting system reliability vary between 30% and 100% depending on the built environment area distribution. For reliabilities below 20% the levelized cost of water is kept below 1 $/m(3) making competitive with the network water tariff.

  • 4. Ekstrom, Henrik
    et al.
    Lafitte, Benoit
    Ihonen, Jari
    Markusson, Henrik
    Jacobsson, Per
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Jannasch, Patric
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Evaluation of a sulfophenylated polysulfone membrane in a fuel cell at 60 to 110 degrees C2007In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 178, no 13-14, p. 959-966Article in journal (Refereed)
    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.

  • 5.
    Ekström, Henrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Hanarp, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Gustavsson, Marie
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Fridell, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    A Novel Approach for Measuring Catalytic Activity of Planar Model Catalysts in the Polymer Electrolyte Fuel Cell Environment2006In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 153, no 4, p. A724-A730Article in journal (Refereed)
    Abstract [en]

    The electrochemical oxygen reduction reaction on nanostructured supported platinum electrodes is measured using a newly developed solid-state polymer electrolyte electrochemical cell. Measurements were made on three types of catalytic surfaces on glassy carbon supports: nanostructured model electrodes prepared by colloidal lithography, a thin thermally evaporated Pt film, and a pure glassy carbon surface. Measurements in nitrogen and oxygen at several different humidities were performed at 60 degrees C in a fuel-cell-like environment. Lowering humidity showed a higher Tafel slope at high potentials for oxygen reduction on the nanostructured catalyst. Good agreement between the electrochemical active area from the hydrogen adsorption peaks and the catalytic area determined from scanning electron microscopy images was found. No significant change of the electrochemically active area with humidity could be found. Double-layer capacitance and oxygen reduction currents increased with increased humidification temperatures.

  • 6. Elia, C. P.
    et al.
    Yang, Zhang
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Mälardalen University, Sweden.
    Hailong, L.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Mälardalen University, Sweden.
    An Open-source Platform for Simulation and Optimization of Clean Energy Technologies2017In: 8th International Conference on Applied Energy, ICAE 2016; Beijing; China; 8 October 2016 through 11 October 2016, Elsevier, 2017, Vol. 105, p. 946-952Conference paper (Refereed)
    Abstract [en]

    This paper is to describe an open-source code for optimization of clean energy technologies. The model covers the whole chain of energy systems including mainly 6 areas: renewable energies, clean energy conversion technologies, mitigation technologies, intelligent energy uses, energy storage, and sustainability. Originally developed for optimization of renewable water pumping systems for irrigation, the open-source model is written in Matlab® and performs simulation, optimization, and design of hybrid power systems for off-grid and on-grid applications. The model uses genetic algorithm (GA) as optimization technique to find the best mix among power sources, storage systems, and back-up sources to minimize life cycle cost, and renewable power system reliability.

  • 7.
    Gode, Peter
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Jaouen, Frederic
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Sundholm, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Influence of the composition on the structure and electrochemical characteristics of the PEFC cathode2003In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, no 28, p. 4175-4187Article in journal (Refereed)
    Abstract [en]

    The influence the composition of the cathode has on its structure and electrochemical performance was investigated for a Nafion content spanning from 10 to 70 wt.%. The cathodes were formed on a Nafion membrane by the spray method and using 20 wt.% Pt on Vulcan (E-TEK). Materials characterisation (SEM, STEM, gas and mercury porosimetry, electron conductivity) and electrochemical characterisation (steady-state polarisation curve, impedance spectroscopy in O-2 and current-pulse measurements in N-2) were performed. The impedance spectra were analysed using our dynamic agglomerate model. The results indicate that the agglomerate model is valid until a Nafion content of about 45 wt.%. Pt/C and Nation are homogeneously mixed for any composition and no Nafion film was observed. The cathodes containing 36-43 wt.% Nation display a single or double Tafel slope behaviour ascribed to diffusion limitations in the agglomerates. At larger Nation content, the agglomerate model can describe the curves only by assuming a diffusion coefficient 3-4 decades smaller than that of gases. At such compositions, the porosity was only 10%. These results were interpreted as a blocking of the pores and a non-percolating pore system for too large Nafion contents.

  • 8.
    Holmström, Niklas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Ihonen, J.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    The influence of the gas diffusion layer on water management in polymer electrolyte fuel cells2007In: Fuel Cells, ISSN 1615-6846, E-ISSN 1615-6854, Vol. 7, no 4, p. 306-313Article in journal (Refereed)
    Abstract [en]

    Performance losses due to flooding of gas diffusion layers (GDLs) and flow fields as well as membrane dehydration are two of the major problems in PEFC. In this investigation, the effect of GDL on the cell water management in PEFC is studied using segmented and single cell experiments. The behaviour of four different commercial GDLs was investigated at both high and low inlet humidity conditions by galvanostatic fuel cell experiments. The influence of varying reactant humidity and gas composition was studied. The results at high inlet humidity show that none of the studied GDLs are significantly flooded on the anode side. On the other hand, when some of the GDLs are used on the cathode side they are flooded, leading to increased mass transfer losses. The results at low inlet humidity conditions show that the characteristics of the GDL influence the membrane hydration. It is also shown that inlet humidity on the anode side has a major effect on flooding at the cathode.

  • 9. Ihonen, J.
    et al.
    Jaouen, F.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Sundholm, G.
    Investigation of mass-transport limitations in the solid polymer fuel cell cathode - II. Experimental2002In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, no 4, p. A448-A454Article in journal (Refereed)
    Abstract [en]

    In this work, we investigated the kinetics and mass-transport limitations of the oxygen reduction reaction in the solid polymer fuel cell. The information obtained from electrochemical experiments and electrode characterization was analyzed with an agglomerate model presented in Part I of this paper. The electrochemical behavior of the cathode was studied by polarizing vs. a hydrogen reference electrode at a low sweep rate. For each potential, the iR-drop was measured with the current-interrupt technique. The cathode structure was investigated by porosimetry and electron microscopy techniques. The effects on the cathode polarization curves of the active layer thickness, oxygen partial pressure, and humidity of the oxygen gas were investigated. On the basis of the model results, conclusions could be drawn regarding the nature of mass-transport limitations because of the characteristic shape of the experimental polarization curves. The simulated curves were fitted to the experimental ones to give the kinetic and masstransport parameters. Finally, we discuss the validity of the model with regard to the values obtained for the transport and structural parameters.

  • 10.
    Jaouen, Frédéric
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Haasl, Sjoerd
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Adhesive copper films for an air-breathing polymer electrolyte fuel cell2005In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 144, no 1, p. 113-121Article in journal (Refereed)
    Abstract [en]

    A design for an air-breathing and passive polymer electrolyte fuel cell is presented. Such a type of fuel cell is in general promising for portable electronics. In the present design, the anode current collector is made of a thin copper foil. The foil is provided with an adhesive and conductive coating, which firstly tightens the hydrogen compartment without mask or clamping pressure, and secondly secures a good electronic contact between the anode backing and the current collector. The cathode comprises a backing, a gold-plated stainless steel mesh and a current collector cut out from a printed circuit board. Three geometries for the cathode current collector were evaluated. Single cells with an active area of 2 cm(2) yielded a peak power of 250-300 MW cm(-2) with air and pure H-2 in a complete passive mode except for the controlled flow of H-2. The cells' response was investigated in steady state and transient modes.

  • 11.
    LAGERGREN, CARINA
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    LUNDBLAD, ANDERS
    KTH, Superseded Departments, Chemical Engineering and Technology.
    BERGMAN, BILL
    KTH, Superseded Departments, Chemical Engineering and Technology.
    SYNTHESIS AND PERFORMANCE OF LICOO2 CATHODES FOR THE MOLTEN CARBONATE FUEL CELL1994In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 141, no 11, p. 2959-2966Article in journal (Refereed)
    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.

  • 12.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Materials characterization of thin film electrodes for PEFC - Survey of methods and an example2004In: Journal of New Materials for Electrochemical Systems, ISSN 1480-2422, Vol. 7, no 1, p. 21-28Article in journal (Refereed)
    Abstract [en]

    Thorough materials characterization is an essential tool for obtaining a deeper understanding of the electrochemical processes taking place in thin film electrodes of polymer fuel cells. This paper gives a survey of different methods for characterizing materials properties that are relevant to the electrochemical performance of such electrodes (i.e. loading, thickness, electrical conductivity, porosity, pore size distribution and pore morphology). The use of these materials characterization methods is exemplified, among other things it is shown that the ionomer (Nafion(R)) in a thin-film electrode made by the spraying method is homogeneously distributed in pores smaller than 40 nm. Furthermore, the ionomer penetrates and/or encapsulates the primary carbon particles of 30 nm. The results are discussed in relation to different MEA fabrication methods.

  • 13.
    Lundblad, Anders
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Schwartz, S.
    Bergman, B.
    Effect of sintering procedures in development of LiCoO2-cathodes for the molten carbonate fuel cell2000In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 90, no 2, p. 224-230Article in journal (Refereed)
    Abstract [en]

    LiCoO2-powder was synthesized from carbonate precursors by calcination in air. Greentapes were tape-cast using a non-aqueous slurry and 10 mu m plastic spheres as pore formers. Sintering was carried out in air at 850-950 degrees C and in argon/air at 500/750 degrees C, The two sintering procedures led to very different sub-micron morphologies, with the primary particles being much smaller in the latter case. The electrochemical performance at 650 degrees C, in terms of overpotential at 160 mA/cm(2), for the air- and argon/air-sintered electrodes was 57 and 81 mV, respectively. The potential drop due to contact resistance between electrode and current collector was estimated to be 100 and 70 mV, respectively. The electrode materials were characterized by scanning electron microscopy (SEM), Hg-porosimetry, the BET-method (N-2-adsorption), X-ray diffractometry (XRD), flame atomic absorption spectrometry (F-AAS), carbon analysis and a van der Pauw conductivity measurement set-up.

  • 14.
    Malmberg, Helena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Modeling an alkaline supercapacitor electrode from activated carbon particlesManuscript (Other academic)
  • 15.
    Malmberg, Helena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    Ruiz, Vanesa
    Instituto Nacional del Carbón (CSIC), Oviedo.
    Blanco, Clara
    Instituto Nacional del Carbón (CSIC), Oviedo.
    Santamaria, Ricardo
    Instituto Nacional del Carbón (CSIC), Oviedo.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    An insight into Faradaic phenomena in activated carbon investigated by means of the microelectrode technique2007In: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 9, no 9, p. 2320-2324Article in journal (Refereed)
    Abstract [en]

    Cyclic voltammetry was performed on activated carbon particles in a microelectrode setup to investigate the behaviour of an activated carbon with oxygen functionalities. Quinoid type redox peaks were clearly seen in the potential region around -0.5 V vs. Hg/HgO. After polarization below -0.4 V, an anodic peak confirms previous studies using a pristine carbon, but in the present work much higher in intensity. In addition, a corresponding cathodic peak, not previously reported, was also found. The appearance of this pair of peaks in a functionalized carbon may be connected to reversible hydrogen adsorption together with Faradaic reactions involving oxygenated functional groups.

  • 16.
    Malmberg, Helena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    Zuleta, Marcelo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    Ionic transport in pores in activated carbons for EDLCs2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 10, p. A1914-A1921Article in journal (Refereed)
    Abstract [en]

    The transport properties and morphology of an activated carbon containing macro-, meso-, and micropores were studied and compared to a sophisticated fully nanoporous carbon that almost lacks meso- and macropores. The morphology of the activated carbon was studied using nitrogen adsorption methods and the pore size distribution was investigated using Barret, Joyner, and Halenda and density functional theory models. The transport properties were studied using a microelectrode technique that allows for determination of the effective diffusivity, D-eff. For the meso/macroporous carbon the effective diffusivity was determined using potential step experiments and analysis for both Cottrell and filling diffusivities were made. The Cottrell diffusivity was smaller than the value of the filling diffusivity, with mean values of (9.4 +/- 3.8) x 10(-14) m(2) s(-1) and (3.1 +/- 1.6) x 10(-12) m(2) s(-1), respectively. This difference in diffusivities is the basis for an agglomerate hypothesis presented for the meso/macroporous carbon. The results for the meso/macroporous carbon are compared with the corresponding results for the sophisticated fully nanoporous carbon. This gave further evidence for the presented agglomerate hypothesis.

  • 17. Matic, H.
    et al.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Jacobsson, P.
    In situ micro-Raman on the membrane in a working PEM cell2005In: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 8, no 1, p. A5-A7Article in journal (Refereed)
    Abstract [en]

    An electrochemical cell has been designed for in situ micro-Raman measurements on the polymer membrane in an operating polymer electrolyte cell (PEM). The method is applicable to studies of both the distribution of water and membrane structure in the working cell environment. An initial study of the water distribution across a Nafion 117 membrane in a cell working as a H-2/H-2 pump cell at hydrogen flow and currents from 0 to 300 mA/cm(2) is presented. The results show that a hydration profile with a lower water content at the anode forms as current is applied to the cell.

  • 18. Noponen, M.
    et al.
    Ihonen, Jari
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Current distribution measurements in a PEFC with net flow geometry2004In: Journal of Applied Electrochemistry, ISSN 0021-891X, E-ISSN 1572-8838, Vol. 34, no 3, p. 255-262Article in journal (Refereed)
    Abstract [en]

    A measurement system for current distribution mapping for a PEFC has been developed. The segmented anode is constructed so as to have high thermal conductivity in order to prevent the formation of large temperature gradients between the electrodes. The construction is therefore feasible for use at high current densities. Both segmented and unsegmented gas diffusion layers are used. The effect of inlet humidification and gas composition at the cathode side is studied. In addition, two different flow geometries are studied. The results show that the measurement system is able to distinguish between current distribution originating from differences in proton conductivity, species concentration and gas diffusion layer properties.

  • 19. Noponen, Matti
    et al.
    Birgersson, Erik
    KTH, Superseded Departments, Mechanics.
    Ihonen, Jari
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Vynnycky, Michael
    KTH, Superseded Departments, Mechanics.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    A two-phase non-isothermal PEFC model: Theory and validation2004In: Fuel Cells, ISSN 1615-6846, E-ISSN 1615-6854, Vol. 4, no 4, p. 365-377Article in journal (Refereed)
    Abstract [en]

    A two-dimensional, non-isothermal, two-phase model of a polymer electrolyte fuel cell (PEFC) is presented. The model is developed for conditions where variations in the stream-wise direction are negligible. In addition, experiments were conducted with a segmented cell comprised of net flow fields. The, experimentally obtained, current distributions were used to validate the PEFC model developed. The PEFC model includes species transport and the phase change of water, coupled with conservation of momentum and mass, in the porous backing of the cathode, and conservation of charge and heat throughout the fuel cell. The current density in the active layer at the cathode is modelled with an agglomerate model, and the contact resistance for heat transfer over the material boundaries is taken into account. Good agreement was obtained between the modelled and experimental polarization curves. A temperature difference of 6°C between the bipolar plate and active layer on the cathode, and a liquid saturation of 6% at the active layer in the cathode were observed at 1 A cm-2.

  • 20.
    Ruiz, Vanesa
    et al.
    Instituto Nacional del Carbón, CSIC, Oviedo.
    Malmberg, Helena
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Blanco, Clara
    Instituto Nacional del Carbón, CSIC, Oviedo.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Santamaría, Ricardo
    Instituto Nacional del Carbón, CSIC, Oviedo.
    A study of Faradaic phenomena in activated carbon by means of macroelectrodes and single particle electrodes2008In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 618, no 1-2, p. 33-38Article in journal (Refereed)
    Abstract [en]

    The electrochemical behaviour of a chemically activated carbon with oxygen-containing surface groups was studied using a conventional macroelectrode configuration with disc electrodes and the single particle microelectrode technique. The results of both experimental set-ups were compare taking into account the visible peaks of the surface groups, capacitance and Faradaic currents. Galvanostatic cycling and cyclic voltammetry performed at different potential windows clearly indicated that the microelectrode configuration was more sensitive to Faradic phenomena (i.e. oxygenated functional groups). The incorporation of mainly CO2-evolving groups after positive polarization may cause the degradation of the carbon material, leading to a distortion in its capacitive behaviour as a result of a restriction of the available surface area.

  • 21.
    von Kraemer, Sophie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Puchner, Mario
    Division of Polymer and Materials Chemistry, Lund University.
    Jannasch, Patric
    Division of Polymer and Materials Chemistry, Lund University.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Erratum: Gas Diffusion Electrodes and Membrane Electrode Assemblies Based on a Sulfonated Polysulfone for High-Temperature PEMFC [J. Electrochem. Soc., 153, A2077 (2006)]2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 12, p. L35-L35Article in journal (Refereed)
  • 22.
    von Kraemer, Sophie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Puchner, Mario
    Division of Polymer and Materials Chemistry, Lund University.
    Jannasch, Patric
    Division of Polymer and Materials Chemistry, Lund University.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Gas Diffusion Electrodes and Membrane Electrode Assemblies Based on a Sulfonated Polysulfone for High-Temperature PEMFC2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 11, p. A2077-A2084Article in journal (Refereed)
    Abstract [en]

    Membrane electrode assemblies MEAs with a sulfonated polysulfone sPSU as the proton-conducting phase were fuel cellevaluated at varying temperatures in over-humidified conditions. The sPSU was prepared by a direct polycondensation involvinga commercially available sulfonated naphthalene diol monomer. The gas diffusion electrodes GDEs and MEAs were successfullyfabricated and a thorough morphological study was subsequently carried out on GDEs with varying sPSU contents and inksolvents. The scanning electron microscopy and porosimetry studies revealed highly porous GDE morphologies at sPSU contentsbelow 20 wt %. Double-layer capacitance measurements showed an almost fully sPSU-wetted electronic phase when the sPSUcontent was 10 wt %. The MEAs were prepared by applying the GDEs directly onto sPSU membranes. MEAs with a total Ptloading of 0.2 mg/cm2 were successfully fuel cell operated at 120°C. The MEAs showed mass-transport limitations in the rangeof 600–800 mA/cm2, most probably caused by abundant water due to the overhumidified measuring conditions. The low resistanceof the MEAs indicated a well-integrated structure between the GDEs and the membrane.

  • 23.
    von Kraemer, Sophie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wikander, Kjell
    Applied Surface Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Palmqvist, Anders E. C.
    Applied Surface Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Evaluation of TiO2 as catalyst support in Pt-TiO2/C composite cathodes for the proton exchange membrane fuel cell2008In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 180, no 1, p. 185-190Article in journal (Refereed)
    Abstract [en]

    Anatase TiO2 is evaluated as catalyst support material in authentic Pt-TiO2/C composite gas diffusion electrodes (GDEs), as a different approach in the context of improving the proton exchange membrane fuel cell (PEMFC) cathode stability. A thermal stability study shows high carbon stability as Pt nanoparticles are supported on TiO2 instead of carbon in the Pt-TiO2/C composite material, presumably due to a reduced direct contact between Pt and C. The performance of Pt-TiO2/C cathodes is investigated electrochemically in assembled membrane-electrode assemblies (MEAs) considering the added carbon fraction and Pt concentration deposited on TiO2. The O-2 reduction current for the Pt-TiO2 alone is expectedly low due to the low electronic conductivity in bulk TiO2. However, the Pt-TiO2/C composite cathodes show enhanced fuel cell cathode performance with growing carbon fraction and increasing Pt concentration deposited on TiO2. The proposed reasons for these observations are improved macroscopic and local electronic conductivity, respectively. Electron micrographs of fuel cell tested Pt-TiO2/C composite cathodes illustrate only a minor Pt migration in the Pt-TiO2/C structure, in which anatase TiO2 is used as Pt support. On the whole, the study demonstrates a stable Pt-TiO2/C Composite material possessing a performance comparable to conventional Pt-C materials when incorporated in a PEMFC cathode.

  • 24.
    Wijngaart, Wouter van der
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Jaouen, Frederic
    Haasl, Sjoerd
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Lundblad, Anders
    Electrochemical device2005Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A polymer electrolyte electrochemical device comprising an anode current collector (1), a membrane electrode assembly (2) with anode and cathode gas backings (3, 4), and a cathode current collector (5), wherein the membrane electrode assembly is sealed and attached at least to the anode current collector by adhesive means, thereby creating an anode gas chamber, and optionally attached to the cathode current collector by adhesive means, said adhesive means being electrically conducting or electrically non-conducting. The invention also relates to polymer electrolyte electrochemical device components adapted for use in a single cell electrochemical device and a series arrangement electrochemical device.

  • 25.
    Wikander, Kjell
    et al.
    Chalmers tekniska högskola, Göteborg.
    Ekström, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Palmqvist, Anders
    Chalmers tekniska högskola, Göteborg.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Holmberg, Krister
    Chalmers tekniska högskola, Göteborg.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Alternative catalysts and carbon support material for PEMFC2006In: Fuel Cells, ISSN 1615-6846, E-ISSN 1615-6854, Vol. 6, no 1, p. 21-25Article in journal (Refereed)
    Abstract [en]

    In order to investigate the possibility of increasing the reactivity for oxygen reduction reaction (ORR) of the cathode in a PEMFC a series of Pt/C catalysts was prepared using water-in-oil microemulsions for synthesizing Pt nanoparticles. The Pt nanoparticles were deposited on porous carbon support (Vulcan XC-72 or a mesoporous carbon) and the catalysts were processed into MEAs. The MEA samples were evaluated and compared with a commercial sample and with Pt/C catalyst samples prepared using a conventional direct impregnation method. The mesoporous carbon support investigated as a potential alternative to Vulcan XC72 has a very high specific surface area and a narrow pore size distribution. The materials were characterized with XRD, TEM, SEM-EDX, N-2 sorption and steady state polarization. It was found that it is possible to increase the ORR reactivity using the microemulsion route for formation of Pt nanoparticles. It was concluded that the MEA processing conditions for the mesoporous carbon support have to be modified to reach improved ORR reactivity, likely due to the large differences in specific surface area, porosity and conductivity compared to the Vulcan carbon.

  • 26.
    Zhang, Yang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Campana, Pietro Elia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Lundblad, Anders
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Wandong, Zheng
    Yan, Jinyue
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Planning and Operation of an Integrated Energy System in a Swedish BuildingManuscript (preprint) (Other academic)
    Abstract [en]

    The increasing capacities of variable renewable energies (VRE) require more flexibility measures. The integration of energy supplies in buildings forms integrated energy systems (IES). IESs can provide flexibility and help increase the VRE penetration level. To upgrade a current building energy system into an IES, several energy conversion and storage components need to be installed. How to decide the component capacities and operate the IES were investigated separately in studies on system planning and system operation. However, a research gap exists that the system configuration from system planning is not validated by real operation conditions in system operation. Meanwhile, studies on system operation assume that the IES configuration is predetermined. This work combines system planning and system operation. The IES configuration is determined by mixed integer linear programming in system planning. Real operation conditions and forecast errors are considered in the system operation. The operation profiles are obtained through different energy management systems. The results indicate that the system configuration from system planning can meet energy demands in real operation conditions. Among different energy management systems, the combination of robust optimization and receding horizon optimization achieves the lowest yearly operation cost. Meanwhile, two scenarios that represent high and low forecast accuracies are employed. Under the high and low forecast accuracy scenarios, the yearly operation costs are about 4% and 6% higher than those obtained from system planning.

  • 27.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Campana, Pietro Elia
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Wang, Lei
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    The Influence of Photovoltaic Models and Battery Models in System Simulation and Optimization2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105C, p. 1185-1192Article in journal (Refereed)
    Abstract [en]

    Selecting accurate and robust models is important for simulation and optimization of a clean energysystem. This paper compares two photovoltaic (PV) models and two battery models in an open-sourcecode, Opti-CE. The PV models are single diode model and its simplified model. The battery models areImproved Shepherd model and energy balance model. The models are compared from a perspective ofoverall system simulation and optimization in particular on both accuracy and computational time. Theresults indicate that simplified PV model causes 0.86% normalized root mean square error (nRMSE)compared with the single diode model, while decreases the simulation time from more than 800s to lessthan 0.01s. The energy balance battery model reduces simulation time from more than 5s to less than0.03s. The energy balance model tends to underestimate the battery State of Charge (SOC) compared withthe Improved Shepherd model. However, the error is not accumulative during the simulation. Comparedto the Pareto front with single diode model and Improved Shepherd model, the simplified PV modelincreases the Pareto front values and result in both higher Self Sufficiency Ratio (SSR) and Net PresentValue (NPV), while the energy balance battery model decreases the part of Pareto front, whereindividuals have low NPV.

  • 28.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Campana, Pietro Elia
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Comparative study of hydrogen storage and battery storage in gridconnected photovoltaic system: Storage sizing and rule-basedoperation2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118Article in journal (Refereed)
    Abstract [en]

    The paper studies grid-connected photovoltaic (PV)-hydrogen/battery systems. The storage componentcapacities and the rule-based operation strategy parameters are simultaneously optimized by theGenetic Algorithm. Three operation strategies for the hydrogen storage, namely conventional operationstrategy, peak shaving strategy and hybrid operation strategy, are compared under two scenarios basedon the pessimistic and optimistic costs. The results indicate that the hybrid operation strategy, whichcombines the conventional operation strategy and the peak shaving strategy, is advantageous in achievinghigher Net Present Value (NPV) and Self Sufficiency Ratio (SSR). Hydrogen storage is further comparedwith battery storage. Under the pessimistic cost scenario, hydrogen storage results in poorer performancein both SSR and NPV. While under the optimistic cost scenario, hydrogen storage achieves higher NPV.Moreover, when taking into account the grid power fluctuation, hydrogen storage achieves better performancein all three optimization objectives, which are NPV, SSR and GI (Grid Indicator).

  • 29.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Ningbo RK Solar Tech. Ltd., China.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Västerås, Sweden.
    Campana, P. E.
    Benavente, F.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Battery sizing and rule-based operation of grid-connected photovoltaic-battery system: A case study in Sweden2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 133, p. 249-263Article in journal (Refereed)
    Abstract [en]

    The optimal components design for grid-connected photovoltaic-battery systems should be determined with consideration of system operation. This study proposes a method to simultaneously optimize the battery capacity and rule-based operation strategy. The investigated photovoltaic-battery system is modeled using single diode photovoltaic model and Improved Shepherd battery model. Three rule-based operation strategies—including the conventional operation strategy, the dynamic price load shifting strategy, and the hybrid operation strategy—are designed and evaluated. The rule-based operation strategies introduce different operation parameters to run the system operation. multi-objective Genetic Algorithm is employed to optimize the decisional variables, including battery capacity and operation parameters, towards maximizing the system's Self Sufficiency Ratio and Net Present Value. The results indicate that employing battery with the conventional operation strategy is not profitable, although it increases Self Sufficiency Ratio. The dynamic price load shifting strategy has similar performance with the conventional operation strategy because the electricity price variation is not large enough. The proposed hybrid operation strategy outperforms other investigated strategies. When the battery capacity is lower than 72 kW h, Self Sufficiency Ratio and Net Present Value increase simultaneously with the battery capacity.

  • 30.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Ningbo RK Solar Tech. Ltd., China.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Campana, Pietro Elia
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Comparative Study of Battery Storage and Hydrogen Storage to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden2016In: PROCEEDINGS OF RENEWABLE ENERGY INTEGRATION WITH MINI/MICROGRID (REM2016) / [ed] Yan, J Zhai, Y Wijayatunga, P Mohamed, AM Campana, PE, ELSEVIER SCIENCE BV , 2016, p. 268-273Conference paper (Refereed)
    Abstract [en]

    Photovoltaic (PV) is promising to supply power for residential buildings. Battery is the most widely employed storage method to mitigate the intermittence of PV and to overcome the mismatch between production and load. Hydrogen storage is another promising method that it is suitable for long-term storage. This study focuses on the comparison of self-sufficiency ratio and cost performance between battery storage and hydrogen storage for a residential building in Sweden. The results show that battery storage is superior to the hydrogen storage in the studied case. Sensitivity study of the component cost within the hydrogen storage system is also carried out. Electrolyzer cost is the most sensitive factor for improving system performance. A hybrid battery and hydrogen storage system, which can harness the advantages of both battery and hydrogen storages, is proposed in the last place.

  • 31.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Campana, Pietro Elia
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Employing Battery Storage to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden2016In: CUE 2015 - APPLIED ENERGY SYMPOSIUM AND SUMMIT 2015: LOW CARBON CITIES AND URBAN ENERGY SYSTEMS, Elsevier, 2016, p. 455-461Conference paper (Refereed)
    Abstract [en]

    Photovoltaic (PV) or hybrid PV-battery systems are promising to supply power for residential buildings. In this study, the load profile of a multi apartment building in Gothenburg and the PV production profile under local weather conditions are compared and analyzed. Three different types of batteries, including lead acid, NaNiCl (Sodium-Nickel-Chloride) and Lithium ion, are studied in combination with the PV systems. It is found that Lithium ion battery system is superior in achieving higher Self-Sufficiency Ratio (SSR) with the same Life Cycle Cost (LCC). Achieving high SSR with the hybrid PV-battery system is unrealistic because of the seasonal mismatch between the load and electricity production profile. The capacity match between the PV and battery to maximize SSR was investigated, showing different trends under system LCC range of 0.1-40 Million SEK (1SEK approximate to 0.12USD). The system LCC should be lower than 10.6 Million SEK (at the SSR of 36%) in order to keep the payback time positive.

  • 32.
    Zuleta, Marcelo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Characterization of the electrochemical and ion-transport properties of a nanoporous carbon at negative polarization by the single-particle method2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 1, p. A48-A57Article in journal (Refereed)
    Abstract [en]

    In this work, the electrochemical processes occurring in a nanoporous carbon, obtained from silicon carbide and used as negative electrode material for supercapacitors, have been investigated by means of the single-particle microelectrode method. The processes studied deal with hydrogen adsorption, evolution, and oxidation using 6 M KOH as electrolyte. It was found that adsorption of hydrogen started at -0.5 V, hydrogen evolution at -1.4 V vs Hg vertical bar HgO, and that hydrogen oxidation occurs in two steps. The first oxidation process takes place between 0 and 0.1 V, shown by a well-defined current peak on the voltammograms. The second oxidation stage occurs between 0.1 and 0.5 V, indicated by a successive increase in current with the number of cycles. It was also found that after the first oxidation process, subsequent cycling between -0.5 and -1 V leads to a larger accumulation of hydrogen inside the nanopores and to a decrease of the effective diffusion coefficient (D-eff) of potassium ions. Subsequent oxidation, in a second process, leads to a total consumption of hydrogen and to an increase of D-eff.

  • 33.
    Zuleta, Marcelo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Effects of pore surface oxidation on electrochemical and mass-transport properties of nanoporous carbon2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 2, p. A270-A276Article in journal (Refereed)
    Abstract [en]

    A new nanoporous (NP) carbon material with a high surface area and a narrow pore size distribution, around 8 A, has been used to investigate the effects that electrochemical oxidation at positive potentials exerts on the capacitance values and effective diffusion coefficients of ions inside the nanopores. An electroanalytical method, based on the single-particle microelectrode technique with micromanipulator, was applied to calculate the diffusion coefficients of 6 M KOH ions in NP carbon. The results were analyzed for short times using the Cottrell model and for long times using the spherical diffusion model. Using cyclic voltammetry, was found that different stages of oxidation took place between 0 and 0.5 V vs. Hg\HgO. After repeated cycling in the first region of oxidation (0-0.3 V), an activation leading to higher capacitance was observed, but the diffusion coefficients decreased from approximately 2 x 10(-9) to 0.5 x 10(-10) cm(2) s(-1). In the second region of oxidation (0.3-0.5 V), where CO2 and 02 evolution can occur, both the capacitance and the diffusion coefficients decreased more dramatically. The effective diffusion coefficients of ions of an activated carbon particle were dependent on the operation potential; decreasing by an order of magnitude when going from -0.3 to +0.3 V. The results are discussed in terms of chemisorption of small oxygen functional groups (-OH or C=O) and ionic interaction with the pore wall.

  • 34.
    Zuleta, Marcelo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Nurk, G.
    Kasuk, H.
    Lust, E.
    Determination of diffusion coefficients of BF4- inside carbon nanopores using the single particle microelectrode technique2006In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 586, no 2, p. 247-259Article in journal (Refereed)
    Abstract [en]

    The electrochemical and mass transport properties of TEABF(4) in a nanoporous (NP) carbon material, obtained from silicon carbide, was studied using single particles and a microelectrode technique. The carbon particles of size 100-200 mu m were studied by cyclic voltammetry and potential step measurements. The effective diffusion coefficients (D-eff) were calculated starting from the asymptotic solutions of Fick's second law for short and long time regions. The results show that cycling at low sweep rates was needed in order for the electrolyte to penetrate the inner porosity of the particles. The carbon material showed different electrochemical and mass transport properties depending on the applied potential. At negative polarisation, the results suggest that TEA(+) was adsorbed on the pore wall, however, being transported very slowly inside the pores. The average D-eff after cycling at both positive and negative potentials was 1.1(+/- 0.4) x 10(-8) cm(2) s(-1), using the Cottrell relation and 1.5(+/- 0.6) x 10(-8) cm(2) s(-1), using the radial diffusion solution. The average value of D-eff after cycling at negative potentials was 1.7(+/- 0.6) x 10(-8) cm(2) s(-1) using both mathematical solutions.

  • 35.
    Zuleta, Marcelo
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Bursell, Martin
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Determination of the effective diffusion coefficient of nanoporous carbon by means of a single particle microelectrode technique2003In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 549, p. 101-108Article in journal (Refereed)
    Abstract [en]

    A single particle microelectrode technique with a micromanipulator was applied and adapted for characterisation of mass transport properties of ionic species in a high surface area nanoporous carbon, with uniform pore size of 8 Angstrom. The effective diffusivity of 6 M KOH in this material was determined by means of potential step experiments on nanoporous carbon particles of different sizes. The results were analysed for short times (Cottrell model) and for long times (spherical diffusion model). The average effective diffusion coefficient for short and long times was 1.5x10(-9) and 1.2x10(-9) cm(2) s(-1), respectively. The relatively small diffusivity values are discussed in terms of interaction between the ion hydration shell and water molecules adsorbed on the pore wall.

  • 36.
    Zuleta, Marcelo
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Bursell, Martin
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Characterization of ion transport in a nanoporous carbon for double layer capacitors2000In: Proceedings of Advances in Science and technology 29: (Mass and Charge Transport in Inorganic Materials: Fundamentals to devices, part A), 2000, p. 439-446Conference paper (Refereed)
1 - 36 of 36
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