Detailed insight into processes of reversible solid oxide cells and stacks using DRT analysis

Subotić, Vanja; Königshofer, Benjamin; Juričić, Đani; Kusnezoff, Mihails; Schröttner, Hartmuth; Hochenauer, Christoph; Boškoski, Pavle

doi:10.1016/j.enconman.2020.113509

Cited by 39 publications

(26 citation statements)

References 52 publications

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“…8a and 9a. This does not explain the shift to lower frequencies but it is shown in [72] that DRT peaks below 1kHz shift to higher frequencies with increasing volume flows at constant current densities. This effect explains the observed frequency shift which does not correlate to the temperature distribution of the cell.…”

Section: Cell Performance and Characterizationmentioning

confidence: 86%

“…1a. This shift might be a result of different volume flows, as shown in [72]. The mean temperature of the cell is 2 K lower when Comp.…”

Section: Cell Performance and Characterizationmentioning

confidence: 94%

“…Only data points with an error of less than 5% are further used to calculate the DRT spectra. Both the Kramers Kronig test and the DRT method are described in more detail by Subotic et al [72]. However, the single cell tests are carried out by supplying the cell with the gas compositions 1a to 10 b from Table 3 at the anode side and the same volume flow (V tot ) of air at the cathode side.…”

Section: Single Cell Testsmentioning

confidence: 99%

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Holistic Approach to Design, Test, and Optimize Stand-Alone SOFC-Reformer Systems

et al. 2021

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Reliable electrical and thermal energy supplies are basic requirements for modern societies and their food supply. Stand-alone stationary power generators based on solid oxide fuel cells (SOFC) represent an attractive solution to the problems of providing the energy required in both rural communities and in rurally-based industries such as those of the agricultural industry. The great advantages of SOFC-based systems are high efficiency and high fuel flexibility. A wide range of commercially available fuels can be used with no or low-effort pre-treatment. In this study, a design process for stand-alone system consisting of a reformer unit and an SOFC-based power generator is presented and tested. An adequate agreement between the measured and simulated values for the gas compositions after a reformer unit is observed with a maximum error of 3 vol% (volume percent). Theoretical degradation free operation conditions determined by employing equilibrium calculations are identified to be steam to carbon ratio (H2O/C) higher 0.6 for auto-thermal reformation and H2O/C higher 1 for internal reforming. The produced gas mixtures are used to fuel large planar electrolyte supported cells (ESC). Current densities up to 500 mA/cm2 at 0.75 V are reached under internal reforming conditions without degradation of the cells anode during the more than 500 h long-term test run. More detailed electrochemical analysis of SOFCs fed with different fuel mixtures showed that major losses are caused by gas diffusion processes.

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Section: Cell Performance and Characterizationmentioning

confidence: 86%

“…1a. This shift might be a result of different volume flows, as shown in [72]. The mean temperature of the cell is 2 K lower when Comp.…”

Section: Cell Performance and Characterizationmentioning

confidence: 94%

Section: Single Cell Testsmentioning

confidence: 99%

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Holistic Approach to Design, Test, and Optimize Stand-Alone SOFC-Reformer Systems

et al. 2021

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“…The main idea of DRT is to distinguish processes which overlap in the frequency-dependent part of an EIS. DRT analysis is used in the literature to investigate different electrochemical systems, such as SOCs [24,25], PEMFCs [26] and batteries [27].…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

Femtosecond Laser-Induced Surface Modification of the Electrolyte in Solid Oxide Electrolysis Cells

et al. 2020

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Electrolyte-supported solid oxide cells are often used for steam electrolysis. Advantages are high mechanical stability and a low degradation rate. The aim of this proof of concept study was to use a femtosecond laser to process the electrolyte of an electrolyte-supported solid oxide cell and evaluate the effect of this laser treatment on the electrochemical performance. The femtosecond laser treatment induces a macroscopic and a superimposed microscopic structure. It can be proven that the electrolyte remains gas tight and the electrochemical performance increases independently of the laser parameters. The initial area-specific resistance degradation during a constant current measurement of 200 h was reduced from 7.9% for a non-treated reference cell to 3.2% for one of the laser-treated cells. Based on electrochemical impedance measurements, it was found that the high frequency resistance of the laser-treated cells was reduced by up to 20% with respect to the reference cell. The impedance spectra were evaluated by calculating the distribution of relaxation times, and in advance, a novel approach was used to approximate the gas concentration resistance, which was related to the test setup and not to the cell. It was found that the low frequency polarization resistance was increased for the laser-treated cells. In total, the area-specific resistance of the laser-treated cells was reduced by up to 14%.

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“…Recently, EIS data recorded could be used in a distribution of relaxation times analysis (DRT) to observe the time constants of individual processes. [45][46][47][48][49] By employing the DRT analysis, researchers could identify the electrochemical properties of microtubular ASC-SOFCs as a function of their microstructure. 50 However, if the criterion of system linearity is neglected, undesired processes within cells are assumed to occur.…”

Section: Introductionmentioning

confidence: 99%

Identification of carbon deposition and its removal in solid oxide fuel cells by applying a non-conventional diagnostic tool

Subotić

Harter

Kusnezoff

et al. 2021

Sustainable Energy Fuels

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Detailed insight into processes of reversible solid oxide cells and stacks using DRT analysis

Cited by 39 publications

References 52 publications

Holistic Approach to Design, Test, and Optimize Stand-Alone SOFC-Reformer Systems

Holistic Approach to Design, Test, and Optimize Stand-Alone SOFC-Reformer Systems

Femtosecond Laser-Induced Surface Modification of the Electrolyte in Solid Oxide Electrolysis Cells

Identification of carbon deposition and its removal in solid oxide fuel cells by applying a non-conventional diagnostic tool

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