A polarization model for a solid oxide fuel cell with a mixed ionic and electronic conductor as electrolyte

Shen, Shuanglin; Yang, Yupeng; Guo, Liejin; Liu, Hongtan

doi:10.1016/j.jpowsour.2014.01.041

Cited by 79 publications

(56 citation statements)

References 21 publications

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“…The electronic conductivity of SDC is taken from a previous modeling work by our group, 23 which is also in line with relevant literature. 9,13,28 In the case of the anode, the scaffold is infiltrated with Cu, whose role is to enhance the electrical conductivity (at 700…”

Section: Model Equations and Variablesmentioning

confidence: 99%

“…Equivalent oxygen partial pressure is a way to represent the chemical potential of the oxide ions inside the MIEC electrolyte. 3,13,31 According to the usual phenomenological correlation, the electronic conductivity depends on the equivalent oxygen partial pressure, while the ionic conductivity does not. Considering the Ohm's law, the electronic leakage current in the electrolyte is expressed as:…”

Section: Model Equations and Variablesmentioning

confidence: 99%

“…A most important result, evidenced by the nature of the model equations and of the tuning parameters, is the dependence of the thermodynamics of the electrolyte from the electrode properties, which allows to show that the electrode properties influence the leakage current and the open circuit voltage. A similar approach is also proposed by Shen et al 13 A one dimensional, steady state model of an IT-SOFC with a MIEC electrolyte is developed, and closed-form equations are provided to predict the leakage current and the open cell voltage, which include the effect of activation and concentration overpotentials. Although the approach is interesting, a zero-dimensional cathode is considered and the anode is assumed as perfectly reversible.…”

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confidence: 99%

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A Distributed Charge Transfer Model for IT-SOFCs Based on Ceria Electrolytes

Rahmanipour

Pappacena

Boaro

et al. 2017

J. Electrochem. Soc.

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A distributed charge transfer model for IT-SOFCs with MIEC electrolyte and composite electrodes is developed. A physically-based description of the electronic leakage current in the electrolyte is included, together with mass and charge conservation equations. The model is applied to simulate experimental polarization curves and impedance spectra collected on IT-SOFCs consisting of SDC electrolytes, Cu-Pd-CZ80 infiltrated anodes and LSCF/GDC composite cathodes. Hydrogen electro-oxidation experiments are examined (H 2 /N 2 humidified mixtures, 700 • C, 30-100% H 2 molar fraction). A significant increase of the ohmic resistance measured in the impedance spectra is revealed at decreasing the H 2 partial pressure or increasing the voltage (from 0.71 cm 2 at 100% H 2 to 0.81 cm 2 at 30% H 2 ). Good agreement between the calculated and experimental polarization and EIS curves is achieved by fitting the exchange current density and the capacitance of each electrode. Model and theoretical analyses allow to rationalize the observed shift of the ohmic resistance, highlighting the key-role played by the electronic leakage current. Overall, the model is able to capture significant kinetic features of IT-SOFCs, and allows to gain insight into relevant parameters for the optimal design of the cell (electrochemically active thickness, current and potential distribution, mass diffusion gradients). Samaria doped Ceria (SDC) and Gadolinia doped Ceria (GDC) are reference electrolyte materials for intermediate temperature solid oxide fuel cell (IT-SOFC) applications, thanks to their high ionic conductivity between 500• C and 700• C. 1-5 Associated to a high ionic conductivity, however, these materials show mixed ionic and electronic conductive (MIEC) properties, and their electronic conductivity increases when exposed to reducing atmospheres. The MIEC character of the electrolyte, in turn, results in the onset of electronic leakage currents (or short circuit currents) and low open-circuit voltage values. The leakage current has a chemical origin and is due to the partial reduction of Ce 4+ ions to Ce 3+ ions, prompted by the different chemical potential at the electrodes: this current is active also in the absence of an electric field applied on the cell, since it stems from the spontaneous transfer of ions across the lattice structure. As a consequence, the effects of the leakage current are not confined to the electrolyte, but extend to the electrodes, and entail a complex relationship with the current drawn from the cell. 6 Deeper insight can therefore be achieved by mathematical modeling.In the literature, comprehensive models can be found, which take into account the MIEC properties of Ce-based electrolytes. Starting from continuum rigorous descriptions, a series of models has been derived for the prediction of impedance spectra collected on MIEC electrolytes, the most important examples being those by Jamnik and Maier, 7 by the group of Haile 8,9 and by Atkinson et al. 10 These models propose closed-form, equivalent circuit-l...

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Section: Model Equations and Variablesmentioning

confidence: 99%

Section: Model Equations and Variablesmentioning

confidence: 99%

mentioning

confidence: 99%

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A Distributed Charge Transfer Model for IT-SOFCs Based on Ceria Electrolytes

Rahmanipour

Pappacena

Boaro

et al. 2017

J. Electrochem. Soc.

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“…Though the OCV is somewhat lower than 0.94 V, it is still higher than that of the SCDC fuel cell 0.85 V, and the power output of the device with 55% LSCF: 45% SCDC raises to 798 mW/cm 2 , see Figure 6. These facts, excluding the SCDC case, are in strong disagreement to the MIEC, which would have acted as a membrane instead of the electrolyte, and would cause significant losses in both voltage and power of the assembled device (Eguchi et al, 1992;Riess et al, 1996;Shen et al, 2014). This has been also proved by using the SCDC electrolyte due to its MIEC behavior in FC environment.…”

Section: Latest Progress On Scientific Studies Of Effcsmentioning

confidence: 98%

“…It is known that the mixed ionic and electronic conductors (MIECs) developed for SOFCs cannot replace the electrolyte. Otherwise, the short-circuiting problem will cause serious device OCV and power output losses (Eguchi et al, 1992;Riess et al, 1996;Shen et al, 2014). The true situation in the EFFCs is very different from the MIEC behavior, because the EFFC does not show OCV loss in a proper composition range of doped ceria ionic materials and semiconductor compared to the pure ionic-doped ceria electrolyte device, which usually exhibits rather lower OCV of 0.85-0.9 V due to the ceria-based electrolyte reduced electronic conduction.…”

Section: Latest Progress On Scientific Studies Of Effcsmentioning

confidence: 99%

Progress in Electrolyte-Free Fuel Cells

Cai

Kim

et al. 2016

Front. Energy Res.

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Solid oxide fuel cell (SOFC) represents a clean electrochemical energy conversion technology with characteristics of high conversion efficiency and low emissions. It is one of the most important new energy technologies in the future. However, the manufacture of SOFCs based on the structure of anode/electrolyte/cathode is complicated and time-consuming. Thus, the cost for the entire fabrication and technology is too high to be affordable, and challenges still hinder commercialization. Recently, a novel type of electrolyte-free fuel cell (EFFC) with single component was invented, which could be the potential candidate for the next generation of advanced fuel cells. This paper briefly introduces the EFFC, working principle, performance, and advantages with updated research progress. A number of key R&D issues about EFFCs have been addressed, and future opportunities and challenges are discussed.

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