Performance of La0.1Sr0.9Co0.8Fe0.2O3− and La0.1Sr0.9Co0.8Fe0.2O3−–Ce0.9Gd0.1O2 oxygen electrodes with Ce0.9Gd0.1O2 barrier layer in reversible solid oxide fuel cells

Choi, Min Sun; Singh, Bhupendra; Wachsman, Eric D.; Song, Sun-Ju

doi:10.1016/j.jpowsour.2013.03.154

Cited by 85 publications

(54 citation statements)

References 32 publications

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“…When plotted in the Nyquist plan (Figures a–c), it can be remarked that all the diagrams exhibit a kind of ‘classical’ Gerischer‐type element. This general shape of the impedance spectra at OCP has been already highlighted by many other authors for the LSCF‐CGO composite electrode , , , , . The frequency distributions of the impedances at OCP are plotted in Figures d–f in the Bode plan.…”

Section: Resultsmentioning

confidence: 99%

Reaction Mechanism and Impact of Microstructure on Performances for the LSCF‐CGO Composite Electrode in Solid Oxide Cells

et al. 2019

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The reaction mechanism and the impact of microstructure on performances for a porous LSCF‐CGO composite used as O2 electrode in SOCs have been investigated. For this purpose, an integrated approach coupling (i) electrochemical testing, (ii) advanced 3D characterizations, and (iii) modeling was proposed. In this frame, a symmetrical cell was tested in a three‐electrode setup and the microstructure of the LSCF‐CGO working electrode was reconstructed by FIB‐SEM tomography. The experimental polarization curves and the impedance diagrams along with the extracted microstructural parameters were used to validate an in‐house microscale electrochemical model. This model considers two parallel reaction pathways with (i) an oxidation/reduction at TPBls (surface path) and (ii) an oxygen transfer at the gas/LSCF interface (bulk path). It was shown that the LSCF‐CGO electrode reaction mechanism is mostly controlled by the charge transfer at TPBls whatever the polarization. Finally, the impact of electrode composition, porosity and particles size on the cell polarization resistance was investigated by using the electrochemical model in combination with a large dataset of synthetic microstructures generated by a geometrical stochastic model. The effect of each microstructural parameter on the electrode performance was analyzed in order to provide useful guidelines for the cell manufacturing.

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Section: Resultsmentioning

confidence: 99%

Reaction Mechanism and Impact of Microstructure on Performances for the LSCF‐CGO Composite Electrode in Solid Oxide Cells

et al. 2019

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“…The observation that the cell Ohmic resistance was minimized for this same condition suggests that the interfacial voids, along with the associated resistive zirconate phase at the voids, do have a deleterious effect that can be eliminated by better matching layer shrinkages. 35,36 The J-V curves in Fig. 14a presents the fuel cell performance of the 1250-red cell with optimized sintering aid concentrations measured at different temperatures.…”

Section: Effect Of Sintering Aid Concentrationmentioning

confidence: 99%

Solid oxide cells with zirconia/ceria Bi-Layer electrolytes fabricated by reduced temperature firing

et al. 2015

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Anode-supported solid oxide cells (SOCs) with thin bi-layer Y 0.16 Zr 0.92 O 2Àd (YSZ)/Gd 0.1 Ce 0.9 O 1.95 (GDC) electrolytes were prepared by a reduced-temperature (1250 C) co-firing process enabled by the addition of a Fe 2 O 3 sintering aid. The Fe 2 O 3 amounts in the layers affected the formation of voids at the GDC/YSZ interface; the case with 1 mol% Fe 2 O 3 in the YSZ layer and 2 mol% Fe 2 O 3 in the GDC layer yielded minimal interfacial voids, presumably because of optimized shrinkage matching between the electrolyte layers during co-firing. The best cells yield fuel cell power density at 0.7 V in air and humidified hydrogen of 1.74 W cm À2 (800 C) and 1.0 W cm À2 (700 C). Under electrolysis conditions, i.e., air and 50 vol% H 2 O-50 vol% H 2 , the best cell area specific resistance is 0.12 U cm 2 at 800 C and 0.27 U cm 2 at 700 C. This excellent cell performance was explained by a number of factors related to the reduced firing temperature: (1) low electrolyte resistance due to minimization of YSZ/GDC interdiffusion; (2) minimal zirconate phase formation between the YSZ and the La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3 (LSFC) cathode because of the dense GDC barrier layer; (3) high three phase boundary density in the Ni-YSZ anode functional layer; and (4) good pore connectivity in the Ni-YSZ support. Preliminary life testing under fuel cell and electrolysis operation shows promising cell stability.

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“…25 The microstructure of the fractured section of the sintered assembly was analyzed using a field-emission scanning electron microscope (FE-SEM, S-4700, Hitachi). The cathode/electrolyte assembly was heated in a microwave furnace at 950 • C for 2 min.…”

Section: Methodsmentioning

confidence: 99%

Investigation of Oxygen Reduction Reaction on La_0.1Sr_0.9Co_0.8Fe_0.2O_3-δElectrode by Electrochemical Impedance Spectroscopy

Choi

Singh

et al. 2015

J. Electrochem. Soc.

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The oxygen reduction reaction (ORR) on La 0.1 Sr 0.9 Co 0.8 Fe 0.2 O 3-δ (LSCF1982) electrode is investigated by electrochemical impedance spectroscopy (EIS) in 550-650 • C range under different oxygen partial pressures (pO 2 ). The distribution function of relaxation time (DRT) analysis of EIS data enabled us to distinguish 3 individual sub-processes contributing toward the overall electrode polarization during ORR. Based on these results, oxygen chemical diffusivity (D chem ) and surface exchange coefficient (K sur ) values are obtained under open circuit voltage (OCV) conditions by Gerischer impedance model. In 500-650 • C range, K sur values ranges between 10 −5 −10 −8 cm·s −1 and D chem values are in 10 −4 −10 −6 cm 2 ·s −1 range which, due to the higher ionic conductivity of LSCF1982, is relatively higher than those for similar mixed-conducting La x Sr 1−x Co 1−y Fe y O 3−δ (LSCF). The values of activation overpotential are separated under the fixed current load, which are well-fitted to the Butler-Volmer equation. Under the current load, the variation of exchange current density (i 0 ) with pO 2 indicated that at the high temperature the total reaction-rate is determined by charge transfer reaction, but when temperature is decreased the reaction-rate is determined by the gas diffusion reaction.

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Performance of La0.1Sr0.9Co0.8Fe0.2O3− and La0.1Sr0.9Co0.8Fe0.2O3−–Ce0.9Gd0.1O2 oxygen electrodes with Ce0.9Gd0.1O2 barrier layer in reversible solid oxide fuel cells

Cited by 85 publications

References 32 publications

Reaction Mechanism and Impact of Microstructure on Performances for the LSCF‐CGO Composite Electrode in Solid Oxide Cells

Reaction Mechanism and Impact of Microstructure on Performances for the LSCF‐CGO Composite Electrode in Solid Oxide Cells

Solid oxide cells with zirconia/ceria Bi-Layer electrolytes fabricated by reduced temperature firing

Investigation of Oxygen Reduction Reaction on La_0.1Sr_0.9Co_0.8Fe_0.2O_3-δElectrode by Electrochemical Impedance Spectroscopy

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Performance of La0.1Sr0.9Co0.8Fe0.2O3− and La0.1Sr0.9Co0.8Fe0.2O3−–Ce0.9Gd0.1O2 oxygen electrodes with Ce0.9Gd0.1O2 barrier layer in reversible solid oxide fuel cells

Cited by 85 publications

References 32 publications

Reaction Mechanism and Impact of Microstructure on Performances for the LSCF‐CGO Composite Electrode in Solid Oxide Cells

Reaction Mechanism and Impact of Microstructure on Performances for the LSCF‐CGO Composite Electrode in Solid Oxide Cells

Solid oxide cells with zirconia/ceria Bi-Layer electrolytes fabricated by reduced temperature firing

Investigation of Oxygen Reduction Reaction on La0.1Sr0.9Co0.8Fe0.2O3-δElectrode by Electrochemical Impedance Spectroscopy

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Investigation of Oxygen Reduction Reaction on La_0.1Sr_0.9Co_0.8Fe_0.2O_3-δElectrode by Electrochemical Impedance Spectroscopy