Rakel Wreland Lindström
Royal Institute of Technology
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Featured researches published by Rakel Wreland Lindström.
Journal of The Electrochemical Society | 2002
Rakel Wreland Lindström; Jan-Erik Svensson; Lars-Gunnar Johansson
The influence of ambient concentrations of carbon dioxide on the NaCl-induced atmospheric corrosion of high purity die-cast MgAl alloys (AM20 and AM60) and MgAlZn alloy (AZ91) is reported. Samples ...
Journal of the American Chemical Society | 2012
Matilda Klett; Marianne Giesecke; Andreas Nyman; Fredrik Hallberg; Rakel Wreland Lindström; Göran Lindbergh; István Furó
Poor mass transport in the electrolyte of Li ion batteries causes large performance losses in high-power applications such as vehicles, and the determination of transport properties under or near operating conditions is therefore important. We demonstrate that in situ (7)Li NMR imaging in a battery electrolyte can directly capture the concentration gradients that arise when current is applied. From these, the salt diffusivity and Li(+) transport number are obtained within an electrochemical transport model. Because of the temporal, spatial, and chemical resolution it can provide, NMR imaging will be a versatile tool for evaluating electrochemical systems and methods.
Journal of The Electrochemical Society | 2000
Rakel Wreland Lindström; Jan-Erik Svensson; Lars-Gunnar Johansson
The atmospheric corrosion of zinc has been studied at 4, 22, and 38°C. The samples were exposed to synthetic air with careful control of CO 2 concentration, relative humidity, and flow conditions. The relative humidity was 95%, and the concentrations of CO 2 were <1 and 350 ppm, respectively. Sodium chloride was added before the exposures (0, 14, and 70 μg/cm 2 ). Mass gain and metal loss results are reported. As expected, NaCl is corrosive toward zinc giving rise to heavy pitting. In the absence of CO 2 , the rate of the NaCl-induced corrosion was found to increase strongly with temperature. However, in the presence of CO 2 , the corrosion rate of zinc is independent of temperature. In the absence of CO 2 . zincite, ZnO, is the dominant corrosion product, while zinc hydroxy carbonates and simonkolleite, Zn 5 (OH) 8 Cl 2 -H 2 O, dominate in the presence of CO 2 . A mechanism is presented that explains the observations.
Journal of The Electrochemical Society | 2001
D. Bengtsson Blücher; Rakel Wreland Lindström; J-E. Svensson; L.‐G. Johansson
A laboratory study of the effect of CO2 and NaCl on the atmospheric corrosion of aluminum is reported. The samples were exposed to pure air with 95% relative humidity and the concentration of CO2 was g/cm(2)). The main result is that the NaCl-induced atmospheric corrosion of aluminum is about 10 to 20 times faster in CO2-free humid air compared to air containing ambient levels of CO2. It is suggested that the rapid corrosion of aluminum coated with NaCl in humid CO2-free air is connected to high-pH areas in the surface electrolyte that develop due to the cathodic reduction of oxygen. The anodic dissolution of aluminum is known to be enhanced by high pH. The unexpected corrosion-inhibitive effect of CO2 is explained by the neutralization of the surface electrolyte. In the absence of CO2, bayerite, Al(OH)(3), forms. Only minute amounts of carbonate were found on the surface after exposure to CO2-containing air.
Journal of The Electrochemical Society | 2002
Rakel Wreland Lindström; Jan-Erik Svensson; Lars-Gunnar Johansson
The influence of salt deposits on the atmospheric corrosion of zinc was studied in the laboratory. Four chloride-containing salts, NaCl, NH 4 Cl, ZnCl 2 , and MgCl 2 , and four sulfate-containing salts, Na 2 SO 4 , (NH 4 ) 2 SO 4 , ZnSO 4 , and MgSO 4 , were investigated. The salts were applied by spraying a saturated ethanol/water solution before exposure. The samples were exposed to purified humid air with careful control of relative humidity (95%), temperature (22.0°C), and air flow. The concentration of CO 2 was 350 ppm and the exposure time was four weeks. The salts formed aqueous solutions on the metal surface. Mass gain and metal loss results are reported. The corrosion products were analyzed by gravimetry, ion chromatography, and X-ray diffraction. It was concluded that zinc corrodes by an electrochemical mechanism. Of the four cations studied, sodium was by far the most corrosive toward zinc. The corrosion of zinc was directly correlated with the amount of sodium ion and did not depend on whether Na 2 SO 4 or NaCI was added. The comparatively rapid corrosion caused by the two sodium salts is suggested to he due to the absence of insoluble sodium compounds. In contrast, the divalent cations precipitate in the cathodic areas due to the high pH values produced, resulting in the blocking of the cathodic sites.
Journal of The Electrochemical Society | 2010
Rakel Wreland Lindström; Katrin Kortsdottir; Maria Wesselmark; Alejandro Oyarce; Carina Lagergren; Göran Lindbergh
This paper discusses the proper measure of the electrochemically active area (ECA)of carbon supported Pt catalyst in PEM fuel cells employing in situ cyclic voltammetry. The charges of the hydrogen ...
Journal of The Electrochemical Society | 2008
Y.E. Seidel; Rakel Wreland Lindström; Z. Jusys; Marie Gustavsson; Per Hanarp; Bengt Kasemo; Alexander Minkow; H.-J. Fecht; R.J. Behm
The stability of nanostructured Pt/glassy carbon (GC) model electrodes upon exposure to a realistic electrochemical/electrocatalytic reaction environment (continuous reaction, continuous electrolyt ...
ChemPhysChem | 2010
Y.E. Seidel; Z. Jusys; Rakel Wreland Lindström; Marie Stenfeldt; Bengt Kasemo; Katharina Krischer
The electrocatalytic oxidation of formaldehyde, which results in CO(2) and HCOOH formation, was investigated under galvanostatic conditions on nanostructured Pt/glassy carbon (GC) electrodes fabricated by employing colloidal lithography (CL). The measurements were performed on structurally well-defined model electrodes of different Pt surface coverages under different applied currents (current densities) and at constant electrolyte transport in a thin-layer flow cell connected to a differential electrochemical mass spectrometry (DEMS) setup to monitor the dynamic response of the reaction selectivity under these conditions. Periodic oscillations of the electrode potential and the CO(2) formation rate appear not only for a continuous Pt film, but also for the nanostructured Pt/GC electrodes when a critical current density is exceeded. The critical current density for achieving regular oscillation patterns increased with decreasing Pt nanodisk density. Lower oscillation frequencies of the electrode potential and lower CO(2) formation rate for nanostructured Pt/GC electrodes compared to continuous Pt film at similar applied current densities suggest that transport processes play an essential role. Moreover, from the simple periodic response of the nanostructured electrodes it follows that all individual Pt disks in the array oscillate in synchrony. This result is discussed in terms of the different modes of spatial coupling present in the system: global coupling, migration coupling and mass transport of the essential chemical species, and the coverage of corresponding adsorbates.
216 th ECS Meeting – Vienna, Austria 4-9 October 2009 | 2009
Rakel Wreland Lindström; Katrin Korstdottir; Göran Lindbergh
This paper aim to discuss a proper measure of the electrochemical active area of carbon supported Pt nanoparticle catalyst used in polymer electrolyte membrane (PEM) fuel cells. The cyclic voltammetric determination of hydrogen under potential deposition (Hupd) and carbon monoxide monolayer oxidation (CO stripping) performed in a fuel cell at fuel cell relevant conditions are compared and the influences of operation temperature (25-80 {degree sign}C) and relative humidity (RH) (40-90% RH) are discussed. The results show that both the shape and the charge of the Hupd are strongly dependent on operating conditions. However, for the CO stripping experiments only a negative shift in potential with increasing temperature or humidity was observed in accordance with results from aqueous electrolytes, whereas the charges for CO monolayer oxidation were almost constant for the temperatures investigated.
Journal of The Electrochemical Society | 2003
Rakel Wreland Lindström; Lars-Gunnar Johansson; Jan-Erik Svensson
The influence of NaNO 3 salt deposits on the atmospheric corrosion of zinc in humid air has been studied. Comparisons are made with the effects of NaCI and Na 2 SO 4 . Also the combined effect of NaNO 3 with NaCI or Na 2 SO 4 was investigated. The salts were applied to zinc samples prior to exposure. The samples were exposed to purified humid air with careful control of relative humidity (95%), temperature (22.0°C), and flow conditions. The CO 2 concentration was 350 ppm and the exposure time was 4 weeks. Mass gain and metal loss results are reported. The corrosion products were analyzed by gravimetry, ion chromatography, and X-ray diffraction. Results show that the corrosion rate in the presence of NaNO 3 is only a third of that registered in the presence of NaCI and Na 2 SO 4 . Further, a slight inhibitive effect of NaNO 3 was found in the presence of NaCI or Na 2 SO 4 . The decreased corrosion rate in the presence of NaNO 3 was attributed to the reduction of nitrate to nitrite at the zinc surface. Nitrite is suggested to act as a corrosion inhibitor toward zinc.