Effect Of Electrolyte Thickness Research Articles

Modeling the concentration profiles of CO and CO2 in a direct carbon solid oxide fuel cell—effect of cathode and electrolyte design parameters

A mathematical model is developed to study the concentration profile of gases, namely carbon dioxide and carbon monoxide, across the anode of a direct carbon solid oxide fuel cell (DC-SOFC) under anode-supported configuration. The concentration profiles are evaluated as a function of cathode and electrolyte design parameters, namely cathode porosity, cathode tortuosity, cathode composition, cathode pressure, electrolyte thickness, and length of the triple-phase boundary (TPB). The effect of operating potential on these concentration profiles is modeled. The effects of electrolyte thickness and TPB length are found to be major factors in determining the performance of the DC-SOFC. Model results are compared with experimental data and found to compare well.

Effects of electrolyte thickness, chloride ion concentration, and an external direct current electric field on corrosion behaviour of silver under a thin electrolyte layer

ABSTRACTEffects of electrolyte thickness, chloride ion concentration, and an external direct current electric field (DCEF) on the corrosion behaviour of silver under a thin electrolyte layer (TEL) were investigated using electrochemical and surface techniques. The results indicate the corrosion rate of silver increases with the decrease of TEL thickness and the increase of chloride ion concentration. Moreover, an interesting conclusion was drawn that the corrosion rate of silver near the positive plate of DCEF first increases and then decreases with the increase of electric field intensity. In a DCEF, different polarisation behaviours of silver at different positions were attributed to the differences of the local corrosion environment.

Investigations on Electrochemical Performance of a Proton-Conducting Ceramic-Electrolyte Fuel Cell with La0.8Sr0.2MnO3 Cathode

The performance of a proton-conducting ceramic-electrolyte fuel cell (PCFC) with BaCe0.85Y0.15O3-δ (BCY15) electrolyte, NiO-BCY15 anode and La0.8Sr0.2MnO3 (LSM) cathode is analyzed in different gas conditions in 600–750°C range. The distribution of relaxation time (DRT) analysis of the electrochemical impedance spectroscopy (EIS) data obtained by varying the gas-flow rate, water vapor pressure (pH2O) and oxygen partial pressure (pO2) is performed to identify the major electrode sub-processes involved in overall electrode reactions. The study of variations in cathodic pO2 shows that the cathodic polarization due to the charge transfer reaction is the major contributor toward the overall electrode polarization resistance. The effect of electrolyte thickness on the fuel cell performance is also studied and a peak power density of ∼0.76 W⋅cm−2 at a current density of ∼1.95 A⋅cm−2 is achieved at 750°C with 8 μm thick electrolyte. The PCFC shows stable performance without any sign of material degradation during the long term operation at a fixed input current for 100 h. The fuel cell performance is compared with those of similar PCFCs with Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF5582), LSM-GDC, and LSM-BCY15 as cathodes, and possible reasons for the observed difference is discussed in terms of the nature of their conductivity.

Numerical Modeling of Galvanic Corrosion Behaviors on Uranium Surface

The Uranium and Titanium corrosion rates are described by a Tafel’s relationship, and the cathodic protection of Uranium is a function of a Wagner number. A numerical simulation of galvanic corrosion of Uranium surface under thin layer electrolyte is presented. The model considered that the effect of a circular defect and oxygen reduction and corrosion in the Uranium surface, the effect of electrolyte thickness and conductivity and defect radius on corrosion current distribution of Uranium with is investigated. The results shows that the corrosion rate at the center is non-uniform, and it could lead to the formation of a hemispherical-shaped pit. And the effect of radius is to increase the importance of the electrode kinetics relative to ohmic resistance, and to increase the potential difference between the center and edge of the Uranium surface, resulting in non-uniform corrosion current distribution.

Effect of electrolyte thickness on the performance of anode-supported ceria cells

Anode-supported ceria cells are promising as SOFCs (solid oxide fuel cells) to be used at intermediate temperatures. However, their performance varies widely depending on the experimental conditions due possibly to the partial electronic conductivity of the acceptor-doped ceria electrolyte that is observed in reducing atmosphere. In this study, the effect of electrolyte thickness on the performance of anode-supported ceria cells was studied. 20 mol% Gd-doped ceria (Gd 0.2Ce 0.8O 2 − δ , GDC20) electrolyte films were coated on the porous Ni-GDC20 anode supports by screen printing and co-firing. BSCF (Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3 − δ ) was used for the cathode. The thickness of the GDC20 electrolyte was found to have a significant effect on the OCV (open circuit voltage), impedance spectra, I–V (current–voltage) and I–P (current–power) curves. When the thickness of the electrolyte decreased from 40 μm to 12 μm in the anode-supported cell, the maximum power densities (P max) increased while the OCV values decreased. The OCV and P max values of the cell with 12 μm of GDC20 electrolyte were 0.772 V and 1.16 Wcm − 2 , respectively, when 97% H 2 + 3% H 2O was used as fuel and open air was used as the oxidant gas at 600 °C. Although a thin electrolyte layer reduces the OCV value, the reduced Ohmic and polarization resistance are advantageous for the cell performance in the tested thickness range because they increased the power density of cell.

Electromotive Potential Distribution and Electronic Leak Currents in Working YSZ Based SOCs

The size of electronic leak currents through the YSZ electrolyte of solid oxide cells have been calculated using basic solid state electrochemical relations and literature data. The distribution of the electromotive potential, of Galvani potential, of concentration of electrons, e, and electron holes, h, was also calculated as these parameters are the basis for the understanding of the electronic conductivity that causes the electronic leak currents. The results are illustrated with examples. The effects of electrolyte thickness, temperature and cell voltage on the electronic leak current density are reported.

Structural design considerations for micromachined solid-oxide fuel cells

Micromachined solid-oxide fuel cells (μSOFCs) are among a class of devices being investigated for portable power generation. Optimization of the performance and reliability of such devices requires robust, scale-dependent, design methodologies. In this first analysis, we consider the structural design of planar, electrolyte-supported, μSOFCs from the viewpoints of electrochemical performance, mechanical stability and reliability, and thermal behavior. The effect of electrolyte thickness on fuel cell performance is evaluated using a simple analytical model. Design diagrams that account explicitly for thermal and intrinsic residual stresses are presented to identify geometries that are resistant to fracture and buckling. Analysis of energy loss due to in-plane heat conduction highlights the importance of efficient thermal isolation in microscale fuel cell design.

Theoretical Analysis of Solid Oxide Fuel Cells: The Effect of Electrode Characteristics

Theoretical analysis which assesses the effect of electrode thickness, electrode porosity, and electrolyte thickness on the performance of a solid oxide fuel cell (SOFC) is presented. The analysis assumes efficient electrocatalysis or zero charge transfer resistance. Transport of H{sub 2}, O{sub 2}, and H{sub 2}O, through the electrodes is assumed to occur by diffusion. The analysis essentially yields the effect of concentration polarization on cell performance. All calculations, which are for operation at 800 C, show that for electrode thicknesses as high as 1 mm, concentration polarization is small for electrode porosity > 10%. By contrast, as expected, the effect of electrolyte thickness is significant. The analysis suggests that a prospective SOFC should consist of a thin electrolyte and relatively thick electrodes. That is, either the anode or the cathode, rather than the electrolyte should be the supporting member of an SOFC.