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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.
    Ahlberg Tidblad, Annika
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Surface analysis with ESCA and GD-OES of the film formed by cathodic reduction of chromate1991Inngår i: Electrochimica Acta, Vol. 36, nr 10, s. 1605-1610Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the chlorate process, a small addition of chromate to the electrolyte results in the formation of a cathode film, which inhibits the reduction of the intermediate hypochlorite ions. To enable surface characterization of the chromium film, it was grown by cathodic reduction onto gold and platinum substrates in hydroxide and chlorate solution. Surface analyses of this film by ESCA and GD-OES indicate that it has a distinct and constant chemical composition during growth given by the formula Cr(OH)3·xH2O. The film is thin, less than 50 Å on platinum and 80 Å on gold. It exhibits poor conductivity and covers the entire cathode surface. © 1991.

  • 3.
    Benavente Araoz, Fabian Andres
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lundblad, Anders
    Res Inst Sweden, RISE, Div Safety & Transport Elect, SE-50462 Boras, Sweden..
    Campana, Pietro Elia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Energiprocesser.
    Zhang, Yang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Energiprocesser.
    Cabrera, Saul
    UMSA Univ Mayor San Andres, Carrera Ciencias Quim, Inst Invest Quim, La Paz, Bolivia..
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Photovoltaic/battery system sizing for rural electrification in Bolivia: Considering the suppressed demand effect2019Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 235, s. 519-528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rural electrification programs usually do not consider the impact that the increment of demand has on the reliability of off-grid photovoltaic (PV)/battery systems. Based on meteorological data and electricity consumption profiles from the highlands of Bolivian Altiplano, this paper presents a modelling and simulation framework for analysing the performance and reliability of such systems. Reliability, as loss of power supply probability (LPSP), and cost were calculated using simulated PV power output and battery state of charge profiles. The effect of increasing the suppressed demand (SD) by 20% and 50% was studied to determine how reliable and resilient the system designs are. Simulations were performed for three rural application scenarios: a household, a school, and a health centre. Results for the household and school scenarios indicate that, to overcome the SD effect, it is more cost-effective to increase the PV power rather than to increase the battery capacity. However, with an increased PV-size, the battery ageing rate would be higher since the cycles are performed at high state of charge (SOC). For the health centre application, on the other hand, an increase in battery capacity prevents the risk of electricity blackouts while increasing the energy reliability of the system. These results provide important insights for the application design of off-grid PV-battery systems in rural electrification projects, enabling a more efficient and reliable source of electricity.

  • 4.
    Benavente-Araoz, Fabian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Campana, P. E.
    Zhang, Yang
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cabrera, S.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Loss-of-load probability analysis for optimization of small off-grid PV-battery systems in Bolivia2017Inngår i: Proceedings of the 9th International Conference on Applied Energy, Elsevier, 2017, Vol. 142, s. 3715-3720Konferansepaper (Fagfellevurdert)
    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.

  • 5. 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.

  • 6.
    Bessman, Alexander
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Soares, Rúdi Cavalerio
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wallmark, Oskar
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Leksell, Mats
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Svens, P.
    Investigating the aging effect of current ripple on lithium-ion cells2015Inngår i: ECS Transactions, Electrochemical Society, 2015, Vol. 69, nr 18, s. 101-106Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have built an experimental setup which exposes twelve cells to a well-defined ripple current. It consists of a system for cycling high capacity cells in parallel with a triangular current waveform superimposed on top of the direct current. The frequency of the waveform is variable up to 50 Hz, and the sum of the DC and AC components can have a magnitude of -40 A to 40 A. Current is measured over a 500 μω shunt resistor. The voltage and current of each cell is read simultaneously at a sample rate up to 4 MS/s, allowing for precise impedance measurements even for high frequency harmonics. The cells are cycled at 40 °C. The experiment has been designed to eliminate indirect effects of the AC harmonics as far as possible. This system is being used to test whether or not AC harmonics affect Li-ion aging.

  • 7.
    Bessman, Alexander
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Soares, Rúdi
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vadivelu, Sunilkumar
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Wallmark, Oskar
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Svens, Pontus
    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.
    Challenging Sinusoidal Ripple-Current Charging of Lithium-Ion Batteries2018Inngår i: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 65, nr 6, s. 4750-4757Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sinusoidal ripple-current charging has previously been reported to increase both charging efficiency and energy efficiency and decrease charging time when used to charge lithium-ion battery cells. In this paper, we show that no such effect exists in lithium-ion battery cells, based on an experimental study of large-size prismatic cells. Additionally, we use a physics-based model to show that no such effect should exist, based on the underlying electrochemical principles.

  • 8.
    Bessman, Alexander
    et al.
    KTH.
    Soares, Rúdi
    KTH.
    Wallmark, Oskar
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Svens, Pontus
    KTH.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Aging effects of AC harmonics on lithium-ion cellsManuskript (preprint) (Annet vitenskapelig)
  • 9.
    Bessman, Alexander
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Soares, Rúdi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Wallmark, Oskar
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Svens, Pontus
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Aging effects of AC harmonics on lithium-ion cells2019Inngår i: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 21, s. 741-749Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With the vehicle industry poised to take the step into the era of electric vehicles, concerns have been raised that AC harmonics arising from switching of power electronics and harmonics in electric machinery may damage the battery. In light of this, we have studied the effect of several different frequencies on the aging of 28 Ah commercial NMC/graphite prismatic lithium-ion battery cells. The tested frequencies are 1 Hz, 100 Hz, and 1 kHz, all with a peak amplitude of 21 A. Both the effect on cycled cells and calendar aged cells is tested. The cycled cells are cycled at a rate of 1C:1C, i.e., 28 A during both charging and discharging, with the exception of a period of constant voltage at the end of every charge. After running for one year, the cycled cells have completed approximately 2000 cycles. The cells are characterized periodically to follow how their capacities and power capabilities evolve. After completion of the test about 80% of the initial capacity remained and no increase in resistance was observed. No negative effect on either capacity fade or power fade is observed in this study, and no difference in aging mechanism is detected when using non-invasive electrochemical methods of post mortem investigation.

  • 10. Birgersson, E.
    et al.
    Nordlund, J.
    Ekstrom, H.
    Vynnycky, M.
    Lindbergh, Göran
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Reduced two-dimensional one-phase model for analysis of the anode of a DMFC2003Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, nr 10, s. A1368-A1376Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An isothermal two-dimensional liquid phase model for the conservation of mass, momentum, and species in the anode of a direct methanol fuel cell (DMFC) is presented and analyzed. The inherent electrochemistry in the DMFC anode active layer is reduced to boundary conditions via parameter adaption. The model is developed for the case when the geometry aspect ratio is small, and it is shown that, under realistic operating conditions, a reduced model, which nonetheless describes all the essential physics of the full model, can be derived. The significant benefits of this approach are that physical trends become much more apparent than in the full model and that there is considerable reduction in the time required to compute numerical solutions, a fact especially useful for wide-ranging parameter studies. Such a study is then performed in terms of the three nondimensional parameters that emerge from the analysis, and we subsequently interpret our results in terms of the dimensional design and operating parameters. In particular, we highlight their effect on methanol mass transfer in the flow channel and on the current density. The results indicate the relative importance of mass-transfer resistance in both the flow channel and the adjacent porous backing.

  • 11.
    Birgersson, Erik
    et al.
    KTH, Tidigare Institutioner, Mekanik.
    Nordlund, Joakim
    KTH, Tidigare Institutioner, Kemiteknik.
    Vynnycky, Michael
    KTH, Tidigare Institutioner, Mekanik.
    Picard, Cyril
    KTH, Tidigare Institutioner, Mekanik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner, Kemiteknik.
    Reduced two-phase model for analysis of the anode of a DMFC2004Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 151, nr 12, s. A2157-A2172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An isothermal two-phase ternary mixture model that takes into account conservation of momentum, mass, and species in the anode of a direct methanol fuel cell (DMFC) is presented and analyzed. The slenderness of the anode allows a considerable reduction of the mathematical formulation, without sacrificing the essential physics. The reduced model is then verified and validated against data obtained from an experimental DMFC outfitted with a transparent end plate. Good agreement is achieved. The effect of mass-transfer resistances in the flow field and porous backing are highlighted. The presence of a gas phase is shown to improve the mass transfer of methanol at higher temperatures (>30 degreesC). It is also found that at a temperature of around 30 degreesC, a one-phase model predicts the same current density distribution as a more sophisticated two-phase model. Analysis of the results from the two-phase model, in combination with the experiments, results in a suggestion for an optimal flow field for the liquid-fed DMFC.

  • 12.
    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.

  • 13.
    Bodén, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    A Model for Mass Transport of Molten Alkali Carbonate Mixtures Applied to the MCFC2006Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 11, s. A2111-A2119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A one-dimensional model based on the Stefan-Maxwell formulation for mass transfer of the main components of a binary molten carbonate electrolyte, including all of the nonidealities, was formulated and applied to the molten carbonate fuel cell (MCFC). The Stefan-Maxwell diffusion coefficients were determined from literature transport data; still, a narrow parameter window in electrolyte composition and temperature had to be used to keep the integrity of the fits. The model for calculation of the electrolyte composition was combined with equations describing the current distribution in the electrodes and the electrolyte. The calculated results of the electrolyte composition changes show that they depend predominantly on the current density and the total electrolyte filling degree. It was also concluded that the electrolyte composition changes are less then two percent for Li/K and five percent for Li/Na. This model demonstrates how experimental data measured at equilibrium conditions may be used to determine Stefan-Maxwell diffusion coefficients and then applied to a transport model for the electrolyte, in this case an MCFC.

  • 14.
    Bodén, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Mass transport in molten alkali carbonate mixtures2006Inngår i: Proc. Electrochem. Soc., 2006, s. 151-161Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A one-dimensional model based on Stefan-Maxwell theory of mass transfer was used to calculate the composition changes of the electrolyte in MCFC. Stefan-Maxwell diffusivities were calculated from conductivity and transport number data and used in the model. The composition changes calculated agreed with experimental results for lithium-potassium carbonate but less for lithium-sodium. The time dependent change of composition was also calculated but this could not explain the difference. In addition, the influence of the porosity of the fuel cell components, together with the electrolyte filling degree, was calculated and this showed a large influence on the composition change.

  • 15.
    Bodén, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Yoshikawa, Masahiro
    Central Research Institute of Electric Power Industry, Energy Conversion Engineering Sector, Kanagawa Japan.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Influence of the anode pore-size distribution and total electrolyte filling degree on the MCFC performance2008Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, nr 2, s. B172-B179Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Experimental data of the total cell reaction resistance as a function of the total electrolyte filling degree was measured to investigate how more electrolyte initially may be added to get as long a cell lifetime as possible. The reaction resistance of each electrode was also measured using two gas compositions and various total electrolyte filling degrees. A theoretical model for the distribution of electrolyte between the anode and the cathode as a function of the total electrolyte filling degree was used to compare the experimental data in this study with data from a symmetrical cell setup. The model takes into account the electrode pore-size distributions and considers two cases for the contact angle between the electrode and the electrolyte for the anode: a zero wetting angle (fully wetted) or reported experimental values for the wetting angle on pure Ni. It was concluded that after the cathode initially has been sufficiently filled with electrolyte the anode pores have to be smaller than the remaining ones of the cathode to allow having the anode act as a reservoir to prolong cell lifetime. The results from the experimental data and the theoretical model for electrolyte distribution were compared with results from a symmetrical setup.

  • 16.
    Bodén, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Yoshikawa, Masahiro
    Central Research Institute of Electric Power Industry, Energy Engineering Research Laboratory, Kanagawa ,Japan.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    The solubility of Ni in molten Li2CO3–Na2CO3 (52/48) in H2/H2O/CO2 atmosphere2007Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 166, nr 1, s. 59-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work the solubility of a Ni-Al anode for MCFC has been studied at atmospheric pressure and two different temperatures using various gas compositions containing H-2/H2O/CO2. It is well known that nickel is dissolved at cathode conditions in an MCFC. However, the results in this study show that nickel can be dissolved also at the anode, indicating that the solubility increases with increasing CO2 partial pressure of the inlet gas and decreasing with increasing temperature. This agrees with the results found by other authors concerning the solubility of NiO at cathode conditions. The dissolution of Ni into the melt can proceed in two ways, either by the reduction of water or by the reduction of carbon dioxide.

  • 17.
    Brown, Shelley
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Baglien, Ida
    Uppsala Univ, Department of Materials Chemistry.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Edström, Kristina
    Uppsala Univ, Department of Materials Chemistry.
    Impact of SOC and Temperature on Surface Film Characteristics of LixNi0.8Co0.15Al0.05O2-based Positive Electrodes Harvested from an Accelerated HEV Ageing MatrixManuskript (Annet vitenskapelig)
  • 18.
    Brown, Shelley
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Temperature and SOC Dependence of the Lifetime Cycling and Calendar Performance of LixNi0.8Co0.15Al0.05O2/Graphite High-Power Batteries for Power-Assist HEV ApplicationsManuskript (Annet vitenskapelig)
  • 19.
    Brown, Shelley
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Georén, Peter
    KTH, Tidigare Institutioner, Kemiteknik.
    Behm, Mårten
    KTH, Tidigare Institutioner, Kemiteknik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner, Kemiteknik.
    Characterisation and modelling of a high-power density lithium-ion positive electrode for HEV application2004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this study, the impedance response of a porous electrode based on LiNi0.8Co0.15Al0.05O2 was investigated using an impedance model including the following features: Butler-Volmer kinetics; double layer capacitance; solid phase concentration and potential gradients; electrolyte phase concentration and potential according to the concentrated electrolyte theory; particle size distribution; and an empirical relation between equilibrium potential and state of charge. The model was evaluated by fitting it to experimental results using different electrolytes and states of charge. In addition, the characteristic parameters for the electrode were obtained from the fitting results.

  • 20.
    Brown, Shelley
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Mellgren, Niklas
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Vynnycky, Michael
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Impedance as a Tool for Investigating Aging in Lithium-Ion Porous Electrodes: II. Positive Electrode Examination2008Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, nr 4, s. A320-A338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-power positive LixNi0.8Co0.15Al0.05O2 composite porous electrodes are known to be the main source of impedance increase in batteries based on GEN2 chemistry. The impedance of positive electrodes, both fresh and harvested from coin cells aged in an accelerated EUCAR hybrid electric vehicle lifetime matrix, was measured in a three-electrode setup and the results fitted with a physically based impedance model. A methodology for fitting the impedance data, including an optimization strategy incorporating a global genetic routine, was used to fit either fresh or aged positive electrodes simultaneously at different states of charge down to 0.5 mHz. The fresh electrodes had an exchange current density of approximately 1.0 A m(-2), a solid-phase diffusion coefficient of approximately 1.4 x 10(-1)5 m(2) s(-1), and a log-normal active particle size distribution with a mean radius of 0.25 mu m. Aged electrode impedance results were shown to be highly dependent on both the electrode state of charge and the pressure applied to the electrode surface. An aging scenario incorporating loss of active particles, coupled with an increase both in the local contact resistance between the active material and the conductive carbon and the resistance of a layer on the current collector, was shown to be adequate in describing the measured aged electrode impedance behavior.

  • 21.
    Brown, Shelley
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Ogawa, Keita
    Adv Engn Serv Co Ltd, Tsukuba.
    Kumeuchi, Youichi
    NEC Tokin Corp, Kanagawa.
    Enomoto, Shinsuke
    NEC Tokin Corp, Kanagawa.
    Uno, Masatoshi
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Sagamihara, Kanagawa.
    Saito, Hirobumi
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Sagamihara, Kanagawa.
    Sone, Yoshitsugu
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Sagamihara, Kanagawa.
    Abraham, Daniel
    Argonne Natl Lab, Div Chem Engn, Argonne.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Cycle Life Evaluation of 3 Ah LixMn2O4-based Lithium-Ion Secondary Cells for Low-Earth-Orbit Satellites: I. Full Cell Results2008Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 185, nr 2, s. 1444-1453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lithium-ion batteries are a candidate for the energy storage system onboard low-earth-orbit satellites. Cycle life performance under both orbital and terrestrial conditions must be investigated in order to evaluate any inadvertent effects due to the former and the validity of the latter, with a successful comparison allowing for the extension of terrestrial experimental matrices in order to identify the effects of ageing. The orbital Performance of LixMn2O4-based pouch cells onboard the microsatellite REIMEI was monitored and compared with terrestrial experiments, with the cells found to be unaffected by orbital conditions. A lifetime matrix of different cycling depths-of-discharge (DODs: 0,20,40%) and temperatures (25, 45 degrees C) was undertaken with periodic reference performance tests. A decrease in both the cell end of-discharge cycling voltage and capacity was accelerated by both higher temperatures and larger DODs. Impedance spectra measured for all ageing conditions indicated that the increase was small, manifested in a state-of-charge dependent increase of the high-frequency semi-circle and a noticeable increase in the high-frequency real axis intercept. An evaluation of the change of both the resistance and capacity of 3 Ah cells led to the development of a potential prognostic state-of-health indicator. The use of elevated temperatures to accelerate cell ageing was validated.

  • 22.
    Brown, Shelley
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Ogawa, Keita
    Adv Engn Serv Co Ltd, Tsukuba.
    Kumeuchi, Youichi
    NEC Tokin Corp, Kanagawa .
    Enomoto, Shinsuke
    NEC Tokin Corp, Kanagawa .
    Uno, Masatoshi
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Kanagawa.
    Saito, Hirobumi
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Kanagawa.
    Sone, Yoshitsugu
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Kanagawa.
    Abraham, Daniel
    Argonne Natl Lab, Div Chem Engn.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Cycle Life Evaluation of 3 Ah LixMn2O4-based Lithium-Ion Secondary Cells for Low-Earth-Orbit Satellites: II. Harvested Electrode Examination2008Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 185, nr 2, s. 1454-1464Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lithium-ion batteries area candidate for the energy storage system onboard low-earth-orbit satellites. Terrestrial experiments are able to capture the performance degradation of cells in orbit, therefore providing the opportunity for lifetime investigations. The lifetime performance of 3 Ah commercial LixMn2O4-based pouch cells was evaluated in a matrix of different cycling depths-of-discharge (DODs: 0, 20,40%) and temperatures (25, 45 degrees C). Aged cells were disassembled and the electrochemical performance of harvested electrodes investigated with two- and three-electrode pouch cells. The positive electrode had a larger decrease in capacity than the negative electrode. Both the positive and negative electrode contributed to the increase of cell impedance measured at high states-of-charge (SOCs). The data at low SOCs indicated that the increase of cell impedance was associated with the positive electrode, which showed a significant increase in the magnitude of the high-frequency semi-circle. This SOC-dependence was observed for cells cycled for either extended periods of time or at higher temperatures with a 40% DOD swing. Low-current cycling of positive electrodes revealed a change in the second potential plateau, possibly reflecting a structural change of the LixMn2O4. This could impact on the electrode kinetics and provide a possible explanation for the SOC-dependent change of the impedance.

  • 23. Bultel, Yann
    et al.
    Wiezell, Katarina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Jaouen, Frédéric
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Ozil, P.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Investigation of mass transport in gas diffusion layer at the air cathode of a PEMFC2005Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 51, nr 3, s. 474-488Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a polymer electrolyte membrane fuel cell (PEMFC), slowdiffusion in the gas diffusion electrode may induce oxygen depletion when using air at the cathode. This work focuses on the behavior of a single PEMFC built with a Nafion® based MEA and an E-TEK gas diffusion layer and fed at the cathode with nitrogen containing 5, 10 and 20% of oxygen and working at different cell temperatures and relative humidities. The purpose is to apply the experimental impedance technique to cells wherein transport limitations at the cathode are significant. In parallel, a model is proposed to interpret the polarization curves and the impedance diagrams of a single PEMFC. The model accounts for mass transport through the gas diffusion electrode. It allows us to qualitatively analyze the experimental polarization curves and the corresponding impedance spectra and highlights the intra-electrode processes and the influence of the gas diffusion layer.

  • 24.
    Bundy, Kenneth
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Karlsson, Mikael
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lundqvist, Anton
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    An electrochemical impedance spectroscopy method for prediction of the state of charge of a nickel-metal hydride battery at open circuit and during discharge1998Inngår i: Journal of Power Sources, Vol. 72, nr 2, s. 118-125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A multivariate method for predicting state of charge, from electrochemical data, of a nickel-metal hydride (NiMH)-battery is presented. Partial least square (PLS) regression is used to evaluate electrochemical impedance spectra and predict state of charge. The impedance spectra are analysed in the frequency range 239-0.6 Hz. The impedance is measured for different states of charge at open-circuit conditions and during continuous discharge at loads ranging between 0.2 C and 0.8 C. When measuring the impedance during discharge, the AC-current signal is imposed on the DC-current. The predictive capability of the method is tested by a cross validation procedure and the root mean square error of prediction is 7% when using the outlier identification capability of the PLS-regression method. The state of charge is evaluated with a single model, independently of whether the cell is subjected to open-circuit or polarised conditions. The predictive performance of the present model decreases at state of charge values less than 10%. © 1998 Elsevier Science S.A.

  • 25. Byrne, P.
    et al.
    Fontes, E.
    Parhammar, O.
    Lindbergh, Göran
    KTH, Tidigare Institutioner                               , Kemiteknik.
    A simulation of the tertiary current density distribution from a chlorate cell - I. Mathematical model2001Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, nr 10, s. D125-D132Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Numerical modeling is becoming an integral part of all research and development within the field of electrolytic systems. A numerical model that calculates the current density distribution and concentration profiles of a chlorate cell is presented here, The results are shown as functions of electrolyte velocity and exchange current density. The model takes into account the three transport mechanisms; diffusion, migration, and convection by considering the development of the flow velocity vector through the channel. It was seen that the developing velocity profile influences the concentration overpotentials, which in turn influences current density distributions. Results from the model show that the total current density decreased along the length of the anode, and that this distribution varied more at lower velocities. In addition, it was seen that migration contributes significantly to species transport, even within the diffusion layer. Finally, the model indicates that the hypochlorite ion is the main participant in the principal side reaction producing oxygen, and not the hypochlorous acid molecule. The results are useful as they increase knowledge of the chlorate process, and can be used to simulate future systems with a wide range of varying parameters such as cell geometry, flow, electrolyte composition, and electrode materials. The aim of the model is to use it as a tool for identifying the sources that contribute to the overpotential in the cell. This article concentrates on the concentration overpotential, which is one of the phenomena that can actually be influenced,

  • 26.
    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.

  • 27.
    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.

  • 28. Ciosek Högström, Katarzyna
    et al.
    Lundgren, Henrik
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wilken, Susanne
    Zavalis, Tommy G.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Edström, Kristina
    Jacobsson, Per
    Johansson, Patrik
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Impact of the flame retardant additive triphenyl phosphate (TPP) on the performance of graphite/LiFePO4 cells in high power applications2014Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 256, s. 430-439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents an extensive characterization of a standard Li-ion battery (LiB) electrolyte containing different concentrations of the flame retardant triphenyl phosphate (TPP) in the context of high power applications. Electrolyte characterization shows only a minor decrease in the electrolyte flammability for low TPP concentrations. The addition of TPP to the electrolyte leads to increased viscosity and decreased conductivity. The solvation of the lithium ion charge carriers seem to be directly affected by the TPP addition as evidenced by Raman spectroscopy and increased mass-transport resistivity. Graphite/LiFePO4 full cell tests show the energy efficiency to decrease with the addition of TPP. Specifically, diffusion resistivity is observed to be the main source of increased losses. Furthermore, TPP influences the interface chemistry on both the positive and the negative electrode. Higher concentrations of TPP lead to thicker interface layers on LiFePO4. Even though TPP is not electrochemically reduced on graphite, it does participate in SEI formation. TPP cannot be considered a suitable flame retardant for high power applications as there is only a minor impact of TPP on the flammability of the electrolyte for low concentrations of TPP, and a significant increase in polarization is observed for higher concentrations of TPP.

  • 29. Ciosek, K.
    et al.
    Killiches, S.
    Zavalis, Tommy
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Johansson, P.
    Edström, K.
    Jacobsson, P.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Energy storage activities in the swedish hybrid vehicle centre2009Inngår i: 24th International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium and Exhibition 2009, EVS 24, 2009, s. 2850-2854Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Significant efforts are put worldwide on developing new concepts for vehicle propulsion with the hybrid electric vehicle (HEV) being a prominent example. Hybrid technology is clearly a strategic future activity for automotive industries and in response to the rapid development in the area; the Swedish Hybrid Vehicle Centre (SHC) was formed in 2007 to join forces between Swedish industry and academia in the field. The centre emphasizes a holistic view to meet the environmental and societal needs with new technological solutions. The research within SHC is currently divided into three different themes where of we here describe the Energy Storage theme with emphasis on the activities carried out at the involved universities in the current main project areas: Cell Properties, Electrode Materials and Electrolyte Additives. Examples are given on how these projects attacks the problems at hand separately, but also how we create synergy effects between the projects. As an example cell modelling is performed given a specific chemistry and cycling scheme, the same parameters are used for electrochemical experiments which provide macroscopic data that are connected with molecular level actions in the electrodes, the electrolyte, and the interfaces. All this is done using our base-line chemistry and a subsequent route is to investigate the role of different additives to overcome the limitations that are observed.

  • 30. Ciosek, K.
    et al.
    Killiches, S.
    Zavalis, Tommy
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Johansson, P.
    Edström, K.
    Jacobsson, P.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Energy storage activities in the Swedish hybrid vehicle centre2009Inngår i: World Electric Vehicle Journal, ISSN 2032-6653, E-ISSN 2032-6653, Vol. 3, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Significant efforts are put worldwide on developing new concepts for vehicle propulsion with the hybrid electric vehicle (HEV) being a prominent example. Hybrid technology is clearly a strategic future activity for automotive industries and in response to the rapid development in the area; the Swedish Hybrid Vehicle Centre (SHC) was formed in 2007 to join forces between Swedish industry and academia in the field. The centre emphasizes a holistic view to meet the environmental and societal needs with new technological solutions. The research within SHC is currently divided into three different themes whereof we here describe the Energy Storage theme with emphasis on the activities carried out at the involved universities in the current main project areas: Cell Properties, Electrode Materials and Electrolyte Additives. Examples are given on how these projects attacks the problems at hand separately, but also how we create synergy effects between the projects. As an example cell modelling is performed given a specific chemistry and cycling scheme, the same parameters are used for electrochemical experiments which provide macroscopic data that are connected with molecular level actions in the electrodes, the electrolyte, and the interfaces. All this is done using our base-line chemistry and a subsequent route is to investigate the role of different additives to overcome the limitations that are observed.

  • 31.
    Cornell, Ann
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Håkansson, Bo
    Lindbergh, Göran
    KTH, Tidigare Institutioner, Kemiteknik.
    Ruthenium based DSA in chlorate electrolysis–critical anode potential and reaction kinetics2003Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, nr 5, s. 473-481Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ruthenium based DSA®s have been investigated in chlorate electrolyte using rotating discs made from commercial electrodes. Measurements of the voltammetric charge, q*, and of iR-corrected polarisation curves up to current densities of 40 kA/m2 were recorded on new anodes and on aged anodes from 3 years of production in a chlorate plant. Anodic polarisation curves in chloride containing electrolytes bend towards a higher slope at approximately 1.2 V versus Ag/AgCl, likely due to oxidation of ruthenium. The potential and current density at which the curves bend have been defined as the critical potential, Ecr, and the critical current density, icr. New anodes that operate at a relatively high potential, >Ecr, obtain an increase in real surface area and thereby a decrease in anode potential and in the selectivity for oxygen formation during the first months of operation. Experiments at constant ionic strength under chlorate process conditions showed that Ecr decreased with increasing chloride concentration with a factor of −0.09 V/log Cl, whereas icr increased with increasing chloride concentration. The chlorine evolution reaction was of the first order with respect to chloride concentration. A possible reaction mechanism for chlorine formation is suggested.

  • 32.
    Cornell, Ann
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Håkansson, Bo
    Lindbergh, Göran
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Ruthenium-based dimensionally stable anode in chlorate electrolysis - Effects of electrolyte composition on the anode potential2003Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, nr 1, s. D6-D12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work the anodic reactions taking place on a dimensionally stable anode (DSA) in chlorate electrolyte have been investigated. Rotating disk electrodes were made from commercial RuO2-catalyzed DSAs and studied in steady-state polarization measurements, mainly IR-corrected polarization curves. Effects of varying pH and electrolyte concentrations of chloride, chlorate, chromium(VI), hypochlorite (ClO- + ClOH) as well as mass transport were studied. The kinetics for the chlorine evolution reaction, with a Tafel slope of 40 mV/decade of current, was not dependent on pH in the region 2-8, at potentials lower than 1.2 V vs. Ag/AgCl. The slope of the polarization curves increased at about 1.2 V vs. Ag/AgCl, a pH-dependent bend not due to mass-transport limitations in the electrolyte. At a pH of 6.5, typical for the chlorate process, oxygen evolution is an important side reaction favored by the dichromate buffer and by increased mass transport, both keeping down the pH at the anode. In the chlorine evolution region the potentials increased when adding Cr(VI) to the electrolyte, whereas no major effect was seen from additions of NaClO. (C) 2002 The Electrochemical Society.

  • 33.
    Cornell, Ann
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner, Kemiteknik.
    Simonsson, Daniel
    KTH, Tidigare Institutioner, Kemiteknik.
    The effect of addition of chromate on the hydrogen evolution reaction and on iron oxidation in hydroxide and chlorate solutions1992Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 37, nr 10, s. 1873-1881Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The addition of chromate to the electrolyte has been shown in previous papers to hinder almost completely the electroreduction of hypochlorite, while the hydrogen evolution reaction can still proceed on the cathode surface. The effect of chromate on the latter reaction has been studied with cyclic voltammetry and by measuring polarization curves for iron electrodes in both chlorate and hydroxide electrolyte. For the sake of comparison, the investigations have also included the effects on the gold electrode in hydroxide solution. The results showed that the kinetics is changed in a way that decreases the differences in electrocatalytic activity between different electrode materials. Also, the innermost layer of the chromium hydroxide film seems to be the most active part in the HER. The chromate also affects the oxidation of the iron surface. A practical result of this is that the activity for the HER on corroded iron in chlorate electrolyte depends on whether the electrolyte contained chromate during the period of corrosion. The activation becomes much smaller if chromate is present.

  • 34. Dannenberg, K.
    et al.
    Ekdunge, P.
    Lindbergh, Göran
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Mathematical model of the PEMFC2000Inngår i: Journal of Applied Electrochemistry, ISSN 0021-891X, E-ISSN 1572-8838, Vol. 30, nr 12, s. 1377-1387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A two-dimensional along-the-channel mass and heat transfer model for a proton exchange membrane fuel cell (PEMFC) is described. The model is used for calculation of cell performance (i.e., cell voltage against current density), ohmic resistance and water profile in the membrane, current distribution and variation of temperature along the gas channels. The following fuel cell regions are considered: gas channels, electrode backings and active layers at the anode and cathode side, and a proton exchange membrane. The model includes mass transfer in the gas channels and electrode gas backings, water transport in the membrane, electrode kinetics and heat transfer. Temperature in the cell is assumed to vary only along the gas channels, which means that it is the same at the anode and cathode and in the solid phase at a specified value of the channel coordinate. Electrode kinetics are considered only at the cathode, where major losses occur, whereas the anode potential is assumed to be equal to its equilibrium value. An agglomerate approach is used for the description of the active layer of the cathode. Simulations are carried out for different humidities of inlet gases, several different stoichiometric amounts of reactants and cooling media (air, water) with different heat transfer coefficients. Analysis of the results showed that the best performance of the PEMFC was obtained for well-humidified gases at conditions close to isothermal and at a stoichiometry of gases only somewhat higher than that corresponding to complete reactant consumption.

  • 35. Darab, Mandi
    et al.
    Barnett, Alejandro Oyarce
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi. SINTEF, Norway.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Thomassen, Magnus Skinlo
    Sunde, Svein
    The Influence of Catalyst Layer Thickness on the Performance and Degradation of PEM Fuel Cell Cathodes with Constant Catalyst Loading2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 232, s. 505-516Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three catalytic layers containing Pt nanoparticles supported on high surface area carbon of different Pt loading but with the same total amount of platinum and therefore of different thickness were employed as cathode catalytic layers (CCLs) in a PEM fuel cell. The layers were subjected to a degradation protocol with an upper potential limit of 1.5 V. Upon exposure to the degradation protocol particle size increased, the electrochemical areas (ECAs) of the catalysts decreased, the catalytic layers became thinner, and the average pore size decreased, indicating both carbon and Pt corrosion. The relative decrease in the ECA was approximately the same for all three layers and was therefore approximately independent of CCL thickness. For all samples the reaction order with respect to oxygen was one half and the samples showed doubling of the slope of the potential vs. log current curve (dEld logi) at high current densities. This indicates that kinetics control the potential at low currents and kinetics and proton migration (ohmic drops in the catalytic layer) at high. However, the degradation protocol also introduced limitations due to oxygen diffusion in the agglomerates. This led to a quadrupling of the dEld logi-slope in 13% oxygen in the samples with the highest catalyst area per volume. For the sample with the lowest catalyst area per volume this slope increased by a factor of six in 13% oxygen, indicating that the local current density exceeded that required for the Tafel slope of the oxygen-reduction reaction (ORR) to double.

  • 36. Das, B
    et al.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Reddy, M. V.
    Chowdari, B. V. R.
    High performance metal nitrides, MN (M = Cr, Co) nanoparticles for non-aqueous hybrid supercapacitors2015Inngår i: Advanced Powder Technology, ISSN 0921-8831, E-ISSN 1568-5527, Vol. 26, nr 3, s. 783-788Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, metal nitrides MN (M = Cr, Co) nanoparticles of particle size similar to 20-30 nm have been prepared under NH3 + N-2 atmosphere at relatively low temperature. The Cr-urea complex was directly converted to CrN with an intermediate formation of Cr2O3, whereas CoN was prepared from Co3O4. These compounds were characterized by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM) techniques. The electrochemical properties were evaluated by galvanostatic cycling, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical performance of the resultant MN nanoparticles showed that they can be used as potential electrode materials for non-aqueous hybrid electrochemical supercapacitors (HESCs). The MN/AC showed high specific capacitance of 75 and 37 F g (1) for M = Cr, Co, respectively when cycled at 30 mA g (1) in non-aqueous electrolyte.

  • 37.
    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.

  • 38.
    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)
  • 39. Dermenci, K.B.
    et al.
    Turan, S.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Effect of cathode slurry composition on the electrochemical properties of Li-ion batteries2015Inngår i: ECS Transactions, ISSN 1938-5862, E-ISSN 1938-6737, Vol. 66, nr 9, s. 285-293Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance difference between commercial and laboratory scale cells remains a problem to be solved. Different way of battery electrode preparation is considered to be the main reason underlying various battery performance. In this work, the effect of slurry composition on electrochemical properties of Li-ion batteries is reported. Slurry preparation with various compositions of LiFePO4 active material (76-88%), PVdF binder (6-12%) and Super P Carbon conductive additive (6-12%) has been studied. Charge-discharge curves and capacity fade of electrodes are also investigated. Selected electrodes were pressed in order to see the effect of pressing on the final performance. Results showed that varying PVdF and carbon content mainly effects charge-discharge characteristics. For unpressed samples, higher amount of PVdF and carbon could result higher maximum specific capacity and lower internal resistance during lithiation and delithiation of positive electrode. Pressing reduces the distance between slurry particles, which enhances the conductivity of the prepared cell.

  • 40. Dolidze, T. D.
    et al.
    Khoshtariya, D. E.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Glaser, Julius
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Two-equivalent electrochemical reduction of a cyano-complex Tl-III(CN)(2) (+) and the novel di-nuclear compound (CN)(5)Pt-II-Tl-III (0)2005Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 50, nr 22, s. 4444-4450Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Extending our recent insights in two-electron transfer microscopic mechanisms for a Tl-III/Tl-I redox system, the electrochemical response of glassy carbon electrode in acidified solutions of Tl-III (ClO4)(3) containing different concentrations of sodium cyanide has been extensively studied for the first time by use of cyclic voltammetry and the CVSIM curve simulation PC program. The complex [Tl-III(CN)(2)](+) has been thoroughly identified electrochemically and shown to display a single welldefined reduction wave (which has no anodic counterpart), ascribed to the two-equivalent process yielding [Tl-I(aq)](+). This behavior is similar to that of [Tl-III (aq)](3+) ion in the absence of sodium cyanide, disclosed in the previous work, and is compatible with the quasi-simultaneous yet sequential two-electron transfer pattern (with two reduction waves merged in one), implying the rate-determining first electron transfer step (resulting in the formation of a covalently interacting di-thallium complex as a metastable intermediate), and the fast second electron transfer step. Some preliminary studies of the two-equivalent reduction of directly metal-metal bonded stable compound [(CN)(5)Pt-II-Tl-III](0) has been also performed displaying two reduction waves compatible with a true sequential pattern.

  • 41. Ebin, B.
    et al.
    Gümen, S.
    Arslan, C.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Electrochemical properties of nanocrystalline LiFe xMn 2-xO 4 (x = 0.2-1.0) cathode particles prepared by ultrasonic spray pyrolysis method2012Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 76, s. 368-374Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The nanocrystalline LiFe xMn 2-xO 4 (x = 0.2-1.0) particles were prepared by ultrasonic spray pyrolysis method using nitrate salts of ingredients at 800°C in air atmosphere. Particle properties were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy. Besides, cyclic voltammetry and galvanostatic tests were performed to investigate the effects of the iron substituent amount on electrochemical behavior. Particle characterization studies show that nanocrystalline particles have spinel structure and they are in submicron size range with spherical morphology. The lowest iron doped sample (LiFe 0.2Mn 1.8O 4) exhibits 117 mAh g -1 cumulative discharge capacity at 0.5 C and 88% capacity retention for 4 V plateau after 50 cycles. At higher iron concentrations, substituent tends to occupy the 8a tetrahedral sites, which prevent the lithium transport in the lattice during charge-discharge process. Increasing of the iron amount in the spinel structure causes the deterioration of the electrochemical performance.

  • 42. Ebin, B.
    et al.
    Gürmen, S.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Electrochemical properties of nanocrystalline LiCu xMn 2-xO 4 (x = 0.2-0.6) particles prepared by ultrasonic spray pyrolysis method2012Inngår i: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 136, nr 2-3, s. 424-430Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The nanocrystalline LiCu xMn 2-xO 4 (x = 0.2-0.6) particles were prepared by ultrasonic spray pyrolysis method using lithium nitrate, manganese nitrate and copper nitrate salts at 800 °C in air atmosphere. Particle properties were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy. Besides, voltammetric and galvanostatic tests were performed to investigate the effects of the copper substituted on electrochemical behavior. Particle characterization studies showed that low copper substituted nanocrystalline particles had single spinel structure, and increasing amount caused tendency of second spinel phase formation. Particles, ranging between 250 nm and 1.5 μm size, were formed by aggregation of nanoparticles. The cumulative discharge capacities of LiCu 0.2Mn 1.8O 4 were determined as 122, 105 and 87 mAh g -1 at 0.5, 1 and 2 C rates, respectively between 4.8 and 3 V potential range. The capacity fade is 44% of initial capacity after 50 cycles at 0.5C rate. Results showed that electrochemical properties of LiCu xMn 2-xO 4 (x = 0.2-0.6) particles were impaired by increasing Cu substitute due to the second phase formation and ionic displacement in the lattice.

  • 43. Ebin, Burcak
    et al.
    Gürmen, Sebahattin
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Preparation and electrochemical properties of spinel LiFexCuyMn1.2O4 by ultrasonic spray pyrolysis2014Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 40, nr 1, s. 1019-1027Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanocrystalline LiFexCuyMn1.2O4 (x and y=0.2, 0.4 and 0.6) particles were prepared by the ultrasonic spray pyrolysis method using nitrate salts at 800 degrees C in air atmosphere. Particle properties were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Also, cyclic voltammetry and galvanostatic tests were performed to investigate the effects of the double substituent and doping amounts on electrochemical behavior. Results show that the aggregation of nanocrystallites around 90 nm size formed submicron spherical cathode particles. Transition metal ratios in particles exhibited a perfect fit with desired amounts. Although the change of iron and copper amounts do not show significant differences in the particle size and shape morphology, they modify the 4 V and 3 V potential plateaus of spinel LiMn2O4. The discharge capacities of LiFe0.2Cu0.6Mn1.2O4 particles are 39 and 23 mAh g(-1) for 4 and 2.6 V potential regions, respectively. 4 V discharge capacity disappeared with increasing of iron and decreasing of copper contents due to random occupation of iron and copper ions in the spinel lattice.

  • 44. Ebin, Burcak
    et al.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Gurmen, Sebahattin
    Preparation and electrochemical properties of nanocrystalline LiBxMn2-xO4 cathode particles for Li-ion batteries by ultrasonic spray pyrolysis method2015Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 620, s. 399-406Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanocrystalline LiBxMn(2-x)O(4) (x = 0.1-0.4) particles are prepared by ultrasonic spray pyrolysis using lithium nitrate, manganese nitrate and boric acid at 800 degrees C in an air atmosphere. The materials properties are characterized by X-ray diffraction, scanning electron microscopy, and atomic absorption spectroscopy. The electrochemical behaviors are investigated with cyclic voltammetry and galvanostatic techniques. The particle characterization studies show that nanocrystalline particles have spinel structure of submicron size with spherical morphology. All boron substituted lithium manganese oxide spinels show improved cycling performance. Among them, LiB0.3Mn1.7O4 particles exhibit 92 mAh g(-1) discharge capacity and 82% capacity retention after 50 cycles at a 0.5 C rate. The higher degree of atomic ordering and the avoidance of the formation of a glass phase in LiBxMn2-xO4 materials are responsible for the better electrochemical performance.

  • 45. Ekstrom, Henrik
    et al.
    Lafitte, Benoit
    Ihonen, Jari
    Markusson, Henrik
    Jacobsson, Per
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Jannasch, Patric
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Evaluation of a sulfophenylated polysulfone membrane in a fuel cell at 60 to 110 degrees C2007Inngår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 178, nr 13-14, s. 959-966Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 46.
    Ekström, Henrik
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Fridholm, B.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Comparison of lumped diffusion models for voltage prediction of a lithium-ion battery cell during dynamic loads2018Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 402, s. 296-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three different time-dependent lumped battery models are presented, using a limited set of only either three or four fitting parameters. The models all include one linear (resistive), one non-linear (kinetic) and one time-dependent element, the latter describing the diffusive processes in the battery. The voltage predictive capabilities of the models versus experimental dynamic load data for a plug-in hybrid vehicle battery are compared. It is shown that models based on a diffusion equation in an idealized particle perform similarly to a model based on an RC (resistive-capacitor) pair. In addition, by exchanging the RC element by a diffusion equation in an idealized particle it is also shown that it is possible to reduce the number of needed fitting parameters by one. 

  • 47.
    Ekström, Henrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Hanarp, Per
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Gustavsson, Marie
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Fridell, Erik
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    A Novel Approach for Measuring Catalytic Activity of Planar Model Catalysts in the Polymer Electrolyte Fuel Cell Environment2006Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 153, nr 4, s. A724-A730Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 48.
    Ekström, Henrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    A model for predicting capacity fade due to SEI formation in a commercial graphite/LiFePO4 cell2015Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 162, nr 6, s. A1003-A1007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An aging model for a negative graphite electrode in a lithium-ion battery, for moderate currents up to 1C, is derived and fitted to capacity fade experimental data. The predictive capabilities of the model, using only four fitted parameters, are demonstrated at both 25°C and 45°C. The model is based on a linear combination of two current contributions: one stemming from parts of the graphite particles covered by an intact microporous solid-electrolyte-interface (SEI) layer, and one contribution from parts of the particles were the SEI layer has cracked due to graphite expansion. Mixed kinetic and transport control is used to describe the electrode kinetics.

  • 49.
    Ekström, Henrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Wickman, Björn
    Chalmers tekniska högskola, Göteborg.
    Gustavsson, Marie
    Chalmers tekniska högskola, Göteborg.
    Hanarp, Per
    Chalmers tekniska högskola, Göteborg.
    Eurenius, Lisa
    Chalmers tekniska högskola, Göteborg.
    Olsson, Eva
    Chalmers tekniska högskola, Göteborg.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Nanometer-thick films of titanium oxide acting as electrolyte in the polymer electrolyte fuel cell2007Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 52, nr 12, s. 4239-4245Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    0-18nm-thick titanium, zirconium and tantalum oxide films are thermally evaporated on Nation 117 membranes, and used as thin spacer electrolyte layers between the Nation and a 3 nm Pt catalyst film. Electrochemical characterisation of the films in terms of oxygen reduction activity, high frequency impedance and cyclic voltammetry in nitrogen is performed in a fuel cell at 80 degrees C and full humidification. Titanium oxide films with thicknesses up to 18 nm are shown to conduct protons, whereas zirconium oxide and tantalum oxide block proton transport already at a thickness of 1.5 nm. The performance for oxygen reduction is higher for a bi-layered film of 3 nm platinum on 1.5 or 18 nm titanium oxide, than for a pure 3 nm platinum film with no spacer layer. The improvement in oxygen reduction performance is ascribed to a higher active surface area of platinum, i.e. no beneficial effect of combining platinum with zirconium, tantalum or titanium oxides on the intrinsic oxygen reduction activity is seen. The results suggest that TiO2 may be used as electrolyte in fuel cell electrodes, and that low-temperature proton exchange fuel cells could be possible using TiO2 as electrolyte.

  • 50.
    Elger, Ragna
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner, Kemiteknik.
    Modelling and experimental validation of the electrochemical behaviour of a li-ion battery during repetitive pulses of charge and discharge2004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this study, a mathematical model describing the electrochemical and thermal behaviour of a cylindrical lithium-ion battery during high rate discharge and charge using a pulse typical for hybrid electric vehicles (HEV) is validated against experimental data. Experiments on the battery were performed in various constant temperature environments during a repeated pulse using high rate charge and discharge. The results show that the voltage losses increase as the temperature is lowered. The measurements show that as a good approximation, the surface temperature during the pulses can be assumed constant. The open circuit potential of LiNi0.8Co0.15Al0.05 was measured using GITT-experiments. The temperature dependence of the open circuit potential of LiNi0.8Co0.15Al0.05 was shown to be negligible. The experimental data will be used to validate the battery model. Some of the model parameters have yet to be fitted to the experimental results before a good agreement between experimental and model results is obtained.

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