Initialization of a methane-fueled single-chamber solid-oxide fuel cell with NiO + SDC anode and BSCF + SDC cathode

The initialization of an anode-supported single-chamber solid-oxide fuel cell, with NiO + Sm_0.2Ce_0.8O_1.9 anode and Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ + Sm_0.2Ce_0.8O_1.9 cathode, was investigated. The initialization process had significant impact on the observed performance of the fuel cell. The in situ reduction of the anode by a methane–air mixture failed. Although pure methane did reduce the nickel oxide, it also resulted in severe carbon coking over the anode and serious distortion of the fuel cell. In situ initialization by hydrogen led to simultaneous reduction of both the anode and cathode; however, the cell still delivered a maximum power density of ∼350 mW cm⁻², attributed to the re-formation of the BSCF phase under the methane–air atmosphere at high temperatures. The ex situ reduction method appeared to be the most promising. The activated fuel cell showed a peak power density of ∼570 mW cm⁻² at a furnace temperature of 600 °C, with the main polarization resistance contributed from the electrolyte.     

Study on calcium and samarium co-doped ceria based nanocomposite electrolytes

Calcium co-doped SDC-based nanocomposite electrolyte (Ce_0.8Sm_0.2−xCa_xO_2−δ-Na₂CO₃) was synthesized by a co-precipitation method. The microstructure and morphology of the composite electrolytes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM), and thermal properties were determined with differential scanning calorimetry (DSC). The particle size, as shown by TEM imaging, was 5-20 nm, which is in a good agreement with the SEM and XRD results. The co-doping effect on both interfaces of the composite electrolyte and doped bulk effect inside the ceria was studied. The excellent performance of the fuel cell was about 1000 mW cm⁻² at 560 °C and at the very low temperature of 350 °C the power density was 200 mW cm⁻². This paper may give a new approach to develop functional nanocomposite electrolyte for low-temperature solid oxide fuel cell (LTSOFC).     

High-performance cathode-supported SOFCs prepared by a single-step co-firing process

Cathode-supported solid oxide fuel cells (SOFCs), comprising porous Pr_0.35Nd_0.35Sr_0.3MnO_3−δ (PNSM)/Sm_0.2Ce_0.8O_1.95 (SDC) cathode supports, SDC function layers, YSZ electrolyte membranes and NiO/SDC anode layers, were successfully fabricated via suspensions coating and single-step co-firing process. The microstructures of electrolyte membranes were observed with scanning electron microscope (SEM). The assembled single cell was electrochemically characterized with humidified hydrogen as fuel and ambient air as oxidant. The open circuit voltage (OCV) of the cell was 1.036 V at 650 °C, and the peak power densities were 657, 472, 290 and 166 mW cm⁻² at 800, 750, 700 and 650 °C, respectively. Impedance analysis indicated that the performance of cathode-supported cell was determined essentially by electrode polarization resistance, which suggested that optimizing electrodes was especially important for improving the cell performance.     

Low-temperature solid oxide fuel cells with novel La0.6Sr0.4Co0.8Cu0.2O3−δ perovskite cathode and functional graded anode

The perovskite La_0.6Sr_0.4Co_0.8Cu_0.2O_3−δ (LSCCu) oxide is synthesized by a modified Pechini method and examined as a novel cathode material for low-temperature solid oxide fuel cells (LT-SOFCs) based upon functional graded anode. The perovskite LSCCu exhibits excellent ionic and electronic conductivities in the intermediate-to-low-temperature range (400-800 °C). Thin Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte and NiO-SDC anode functional layer are prepared over macroporous anode substrates composed of NiO-SDC by a one-step dry-pressing/co-firing process. A single cell with 20 μm thick SDC electrolyte on a porous anode support and LSCCu-SDC cathode shows peak power densities of only 583.2 mW cm⁻² at 650 °C and 309.4 mW cm⁻² for 550 °C. While a cell with 20 μm thick SDC electrolyte and an anode functional layer on the macroporous anode substrate shows peak power densities of 867.3 and 490.3 mW cm⁻² at 650 and 550 °C, respectively. The dramatic improvement of cell performance is attributed to the much improved anode microstructure that is confirmed by both SEM observation and impedance spectroscopy. The results indicate that LSCCu is a very promising cathode material for LT-SOFCs and the one-step dry-pressing/co-firing process is a suitable technique to fabricate high performance SOFCs.     

Ethane dehydrogenation over nano-Cr2O3 anode catalyst in proton ceramic fuel cell reactors to co-produce ethylene and electricity

Ethane and electrical power are co-generated in proton ceramic fuel cell reactors having Cr₂O₃ nanoparticles as anode catalyst, BaCe_0.8Y_0.15Nd_0.05O_3−δ (BCYN) perovskite oxide as proton conducting ceramic electrolyte, and Pt as cathode catalyst. Cr₂O₃ nanoparticles are synthesized by a combustion method. BaCe_0.8Y_0.15Nd_0.05O_3−δ (BCYN) perovskite oxides are obtained using a solid state reaction. The power density increases from 51 mW cm⁻² to 118 mW cm⁻² and the ethylene yield increases from about 8% to 31% when the operating temperature of the solid oxide fuel cell reactor increases from 650 °C to 750 °C. The fuel cell reactor and process are stable at 700 °C for at least 48 h. Cr₂O₃ anode catalyst exhibits much better coke resistance than Pt and Ni catalysts in ethane fuel atmosphere at 700 °C.     

La2NiO4+δ potential cathode material on La0.9Sr0.1Ga0.8Mg0.2O2.85 electrolyte for intermediate temperature solid oxide fuel cell

La₂NiO_4+δ, a mixed ionic-electronic conducting oxide with K₂NiF₄ type structure, has been studied as cathode material with La_0.9Sr_0.1Ga_0.8Mg_0.2O_2.85 (LSGM) electrolyte for intermediate solid oxide fuel cells (IT-SOFCs). XRD results reveal excellent chemical compatibility between the La₂NiO_4+δ sample and LSGM electrolyte.A single cell (0.22 cm² active area) was fabricated with La₂NiO_4+δ as cathode, Ni-Sm_0.2Ce_0.8O_1.9 (2:1; w/w) as anode and LSGM as electrolyte. A thin buffer layer of Sm_0.2Ce_0.8O_1.9 (SDC) between anode and electrolyte was used to avoid possible interfacial reactions. The cell was tested under humidified H₂ and stationary air as fuel and oxidant, respectively. The electrochemical behaviour was evaluated by means of current-voltage curves and impedance spectroscopy. Microstructure and morphology of the cell components were analysed by SEM-EDX after testing.The maximum power densities were 160, 226, and 322 mW cm⁻² at 750, 800 and 850 °C, respectively with total polarisation resistances of 0.77, 0.48 and 0.31 Ω cm² at these temperatures. Cell performance remained stable when a current density of 448 mA cm⁻² was demanded for 144 h at 800 °C, causing no apparent degradation in the cell. The performance of this material may be further improved by reducing the electrolyte thickness and optimisation of the electrode microstructure.     

Electrochemical performance of (Ba0.5Sr0.5)0.9Sm0.1Co0.8Fe0.2O3−δ as an intermediate temperature solid oxide fuel cell cathode

This study presents the electrochemical performance of (Ba_0.5Sr_0.5)_0.9Sm_0.1Co_0.8Fe_0.2O_3−δ (BSSCF) as a cathode material for intermediate temperature solid oxide fuel cells (IT-SOFC). AC-impedance analyses were carried on an electrolyte supported BSSCF/Sm_0.2Ce_0.8O_1.9 (SDC)/Ag half-cell and a Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF)/SDC/Ag half-cell. In contrast to the BSCF cathode half-cell, the total resistance of the BSSCF cathode half-cell was lower, e.g., at 550 °C; the values for the BSSCF and BSCF were 1.54 and 2.33 Ω cm², respectively. The cell performance measurements were conducted on a Ni-SDC anode supported single cell using a SDC thin film as electrolyte, and BSSCF layer as cathode. The maximum power densities were 681 mW cm⁻² at 600 °C and 820 mW cm⁻² at 650 °C.     

A simple and effective process for Sr0.995Ce0.95Y0.05O3−δ and BaCe0.9Nd0.1O3−δ solid electrolyte ceramics

A simple and effective reaction-sintering process for Sr_0.995Ce_0.95Y_0.05O_3−δ and BaCe_0.9Nd_0.1O_3−δ solid electrolyte ceramics was investigated in this study. Without any calcination involved, the mixture of raw materials was pressed and sintered directly. Sr_0.995Ce_0.95Y_0.05O_3−δ ceramics with 98.4% of the theoretical density were obtained after being sintered at 1350 °C for 2 h. A total conductivity 1.42 mS cm⁻¹ at 900 °C could be obtained in Sr_0.995Ce_0.95Y_0.05O_3−δ sintered at 1500 °C for 4 h. BaCe_0.9Nd_0.1O_3−δ ceramics with 91.7% of the theoretical density were obtained after being sintered at 1500 °C for 2 h. A total conductivity 11.54 mS cm⁻¹ at 900 °C could be obtained in BaCe_0.9Nd_0.1O_3−δ sintered at 1350 °C for 6 h. The reaction-sintering process has proven a simple and effective method to obtain useful Sr_0.995Ce_0.95Y_0.05O_3−δ and BaCe_0.9Nd_0.1O_3−δ ceramics for solid electrolyte applications in solid oxide fuel cells.     

Sm0.2(Ce1−xTix)0.8O1.9 modified Ni-yttria-stabilized zirconia anode for direct methane fuel cell

Sm_0.2(Ce_1−xTi_x)_0.8O_1.9 (SCTx, x = 0-0.29) modified Ni-yttria-stabilized zirconia (YSZ) has been fabricated and evaluated as anode in solid oxide fuel cells for direct utilization of methane fuel. It has been found that both the amount of Ti-doping and the SCTx loading level in the anode have substantial effect on the electrochemical activity for methane oxidation. Optimal anode performance for methane oxidation has been obtained for Sm_0.2(Ce_0.83Ti_0.17)_0.8O_1.9 (SCT0.17) modified Ni-YSZ anode with SCT0.17 loading of about 241 mg cm⁻² resulted from four repeated impregnation cycles. When operating on humidified methane as fuel and ambient air as oxidant at 700 °C, single cells with the configuration of SCT0.17 modified Ni-YSZ anode, YSZ electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O₃-Sm_0.2Ce_0.8O_1.9 (LSCF-SDC) composite cathode show the polarization cell resistance of 0.63 Ω cm² under open circuit conditions and produce a peak power density of 383 mW cm⁻². It has been revealed that the coated Ti-doped SDC on Ni-YSZ anode not only effectively prevents the methane fuel from directly impacting on the Ni particles, but also enhances the kinetics of methane oxidation due to an improved oxygen storage capacity (OSC) and redox equilibrium of the anode surface, resulting in significant enhancement of the SCTx modified Ni-YSZ anode for direct methane oxidation.     

Combustion synthesized Nd2−xCexCuO4 (x = 0-0.25) cathode materials for intermediate temperature solid oxide fuel cell applications

It is found that the solid solubility of Ce in Nd_2−xCe_xCuO_4±δ is limited up to x = 0.2. A semiconductor to metallic transition is observed at 600 °C in d.c. conductivity data, which coincides with a transition in temperature-dependent area-specific resistance (ASR). Nd_1.8Ce_0.2CuO_4±δ is thermodynamically and chemically stable against gadolinia-doped ceria (GDC) up to 1200 °C. On the other hand, it reacts with a yttria-stabilized zirconia electrolyte to form Nd₂Zr₂O₇. At 700 °C, the ASR of a Nd_1.8Ce_0.2CuO_4±δ/GDC/Nd_1.8Ce_0.2CuO_4±δ cell sintered at 800 °C is 0.13 ohm cm², and the ASR proportionally improves with increase in the sintering temperature of the electrochemical cell. The improved ASR and electrochemical performance are attributed to the nanocrystalline nature of the cathode material.     

Fabrication and performance of a proton-conducting solid oxide fuel cell based on a thin BaZr0.8Y0.2O3−δ electrolyte membrane

A dense BaZr_0.8Y_0.2O_3−δ (BZY) proton-conducting electrolyte membrane is successfully fabricated on a NiO-BaZr_0.1Ce_0.7Y_0.2O_3−δ (NiO-BZCY) anode substrate by a co-pressing process after co-firing at 1400 °C. BZY powders are synthesized via a citric acid-nitrate gel combustion process after calcination at 1100 °C. The SEM results reveal that the BZY membrane is crack-free, very dense, and 20 μm thick. A single cell with Sm_0.5Sr_0.5CoO_3−δ-Ce_0.8Sm_0.2O_2−δ (SSC-SDC) as the cathode is assembled and tested with wet hydrogen (2% H₂O) as the fuel and static air as the oxidant. The open circuit voltages (OCVs) are 0.953, 0.987, 1.014, and 1.039 V at 700, 650, 600, and 550 °C, respectively. A maximum power density of 170 mW cm⁻² is obtained at 700 °C. Resistances of the testing cell are investigated under open circuit conditions at different operating temperatures by impedance spectroscopy.     

Comparative study on the performance of a SDC-based SOFC fueled by ammonia and hydrogen

A nickel-based anode-supported solid oxide fuel cell (SOFC) was assembled with a 10 μm thick Ce_0.8Sm_0.2O_2−δ (SDC) electrolyte and a Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) cathode. The cell performance was investigated with hydrogen and ammonia gas evaporated from liquefied ammonia as fuel. Fueled by hydrogen the maximum power densities were 1872, 1357, and 748 mW cm⁻² at 650, 600, and 550 °C, respectively. While with ammonia as fuel, the cell showed the maximum power densities of 1190, 434, and 167 mW cm⁻², correspondingly. The power densities lower than that predicted, particularly at the lower operating temperatures for ammonia fuel cell, compared to hydrogen fuel cell, could be attributed to actual lower temperature than thermocouple display due to endothermic reaction of ammonia decomposition as well as the rather larger inlet ammonia flow rate. The results demonstrated that the ammonia was a right convenient liquid fuel for SOFCs as long as it was keeping the decomposition completion of ammonia in the cell or before entering the cell.     

Bimetallic (Ni–Fe) anode-supported solid oxide fuel cells with gadolinia-doped ceria electrolyte

Anode-supported solid oxide fuel cells (SOFC) comprising nickel + iron anode support and gadolinia-doped ceria (GDC) of composition Gd_0.1Ce_0.9O_2−δ thin film electrolyte were fabricated, and their performance was evaluated. The ratio of Fe₂O₃ to NiO in the anode support was 3 to 7 on a molar basis. Fe₂O₃ and NiO powders were mixed in the desired proportions and discs were die-pressed. All other layers were sequentially applied on the anode support. The cell structure consisted of five distinct layers: anode support – Ni + Fe; anode functional layer – Ni + GDC; electrolyte – GDC; cathode functional layer – LSC (La_0.6Sr_0.4CoO_3−δ) + GDC; and cathode current collector – LSC. Cells with three different variations of the electrolyte were made: (1) thin GDC electrolyte (∼15 μm); (2) thick GDC electrolyte (∼25 μm); and (3) tri-layer GDC/thin yttria-stabilized zirconia (YSZ)/GDC electrolyte (∼25 μm). Cells were tested with hydrogen as fuel and air as oxidant up to 650 °C. The maximum open circuit voltage measured at 650 °C was ∼0.83 V and maximum power density measured was ∼0.68 W cm⁻². The present work shows that cells with Fe + Ni containing anode support can be successfully made.     

Optimization of the interface polarization of the La2NiO4-based cathode working with the Ce1–xSmxO2–δ electrolyte system

The performance of La₂NiO₄ cathode material and Ce_1–xSm_xO_2–δ (x = 0.1, 0.2, 0.3, 0.4) electrolyte system was analyzed. Ceria-based materials were prepared by the freeze-drying precursor route whereas La₂NiO₄ was prepared by the nitrate–citrate procedure. Electrolyte pellets were obtained after sintering the powders at 1600 °C for 10 h. Also dense ceria-based electrolytes samples were obtained by calcining the powders at 1150 °C after the addition of 2 mol%-Co. Interface polarization measurements were performed by impedance spectroscopy in air at open circuit voltage, using symmetrical cells prepared after the deposition of porous La₂NiO₄-electrodes on the Ce_1–xSm_xO_2–δ system. X-ray diffraction (XRD) of cathode materials after using in symmetrical cells confirmed no significant reaction between La₂NiO₄ and ceria-based electrolytes. The efficiency of the cathode material is highly dependent on the composition of the electrolyte, and low-content Sm-doped ceria samples revealed an important decrease in the performance of the system. Differences in electrochemical behaviour were attributed principally to the oxide ion transference between cathode and electrolyte, and were correlated to the conductivity of the electrolyte. In this way cobalt-doped electrolytes with a Sm-content ≤30% perform better than free-cobalt samples due to the increase in grain boundary conductivity. Finally, composites of the ceria-based materials and La₂NiO₄ to use as cathode were prepared and an important increase of the interface performance was observed compared to La₂NiO₄ pure cathode. Predictions of maximun power density were obtained by the mixed transport properties of the electrolytes and by the interface polarization results. The use of composite materials could allow to increase the performance of the cell from 170 mW cm⁻² for pure La₂NiO₄ cathode, to 370 mW cm⁻² for La₂NiO₄–Ce_0.8Sm_0.2O_2–δ cathode, both working with Ce_0.8Sm_0.2O_2–δ electrolyte 300 μm in thickness and Ni–Ce_0.8Sm_0.2O_2–δ as anode at 800 °C.     

Electrochemical performance of a solid oxide fuel cell based on Ce0.8Sm0.2O2−δ electrolyte synthesized by a polymer assisted combustion method

A polyvinyl alcohol assisted combustion synthesis method was used to prepare Ce_0.8Sm_0.2O_2−δ (SDC) powders for an intermediate temperature solid oxide fuel cell (IT-SOFC). The XRD results showed that this combustion synthesis route could yield phase-pure SDC powders at a relatively low calcination temperature. A thin SDC electrolyte film with thickness control was produced by a dry pressing method at a lower sintering temperature of 1250 °C. With Sm_0.5Sr_0.5Co₃-SDC as the composite cathode, a single cell based on this thin SDC electrolyte was tested from 550 to 650 °C. The maximum power density of 936 mW cm⁻² was achieved at 650 °C using humidified hydrogen as the fuel and stationary air as the oxidant.     

A cobalt-free SrFe0.9Sb0.1O3−δ cathode material for proton-conducting solid oxide fuel cells with stable BaZr0.1Ce0.7Y0.1Yb0.1O3−δ electrolyte

A cobalt-free cubic perovskite oxide SrFe_0.9Sb_0.1O_3−δ (SFSb) is investigated as a novel cathode for proton-conducting solid oxide fuel cells (H-SOFCs). XRD results show that SFSb cathode is chemically compatible with the electrolyte BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ (BZCYYb) for temperatures up to 1000 °C. Thin proton-conducting BZCYYb electrolyte and NiO-BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ (NiO-BZCYYb) anode functional layer are prepared over porous anode substrates composed of NiO-BZCYYb by a one-step dry-pressing/co-firing process. Laboratory-sized quad-layer cells of NiO-BZCYYb/NiO-BZCYYb/BZCYYb/SFSb are operated from 550 to 700 °C with humidified hydrogen (∼3% H₂O) as fuel and the static air as oxidant. An open-circuit potential of 0.996 V, maximum power density of 428 mW cm⁻², and a low electrode polarization resistance of 0.154 Ω cm² are achieved at 700 °C. The experimental results indicate that the cobalt-free SFSb is a promising candidate for cathode material for H-SOFCs.     

Prontonic ceramic membrane fuel cells with layered GdBaCo2O5+x cathode prepared by gel-casting and suspension spray

In order to develop a simple and cost-effective route to fabricate protonic ceramic membrane fuel cells (PCMFCs) with layered GdBaCo₂O_5+x (GBCO) cathode, a dense BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY7) electrolyte was fabricated on a porous anode by gel-casting and suspension spray. The porous NiO–BaZr_0.1Ce_0.7Y_0.2O_3−δ (NiO–BZCY7) anode was directly prepared from metal oxide (NiO, BaCO₃, ZrO₂, CeO₂ and Y₂O₃) by a simple gel-casting process. A suspension of BaZr_0.1Ce_0.7Y_0.2O_3−δ powders synthesized by gel-casting was then employed to deposit BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY7) thin layer by pressurized spray process on NiO–BZCY7 anode. The bi-layer with 10 μm dense BZCY7 electrolyte was obtained by co-sintering at 1400 °C for 5 h. With layered GBCO cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H₂ as fuel and the static air as oxidant. An open-circuit potential of 0.98 V, a maximum power density of 266 mW cm⁻², and a low polarization resistance of the electrodes of 0.16 Ω cm² was achieved at 700 °C.     

A novel electronic current-blocked stable mixed ionic conductor for solid oxide fuel cells

A novel ionic conductor, BaCe_0.8Sm_0.2O_3−δ-Ce_0.8Sm_0.2O_2−δ (BCS-SDC, weight ratio 1:1), is reported as an electrolyte material for solid oxide fuel cells (SOFCs). Homogeneous BCS-SDC composite powders are synthesized via a one-step gel combustion method. The BCS and SDC crystalline grains play a role as matrix for each other in the composite electrolyte. The composite avoids the typical drawbacks of BCS and SDC, showing not only a better chemical stability than the single phase of BCS but much higher open circuit voltages (OCVs) than the single phase of SDC under the fuel cell conditions. Moreover, BCS-SDC exhibits mixed oxygen ionic and protonic conduction. A total conductivity of 0.0204 S cm⁻¹ at 700 °C is achieved in wet hydrogen (3% H₂O), the value of which is comparable with the state-of-the-art proton conductor BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY). The peak power density achieves 505 mW cm⁻² at 700 °C with a 30-μm-thick BCS-SDC electrolyte using wet H₂ as the fuel. Resistances of the tested cell under open circuit conditions at different operating temperatures are also investigated by impedance spectroscopy.     

Fabrication and characterization of anode-supported micro-tubular solid oxide fuel cell based on BaZr0.1Ce0.7Y0.1Yb0.1O3−δ electrolyte

Anode-supported micro-tubular solid oxide fuel cells (SOFCs) based on a proton and oxide ion mixed conductor electrolyte, BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ (BZCYYb), have been fabricated using phase inversion and dip-coating techniques with a co-firing process. The single cell is composed of NiO-BZCYYb anode, BZCYYb electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF)-BZCYYb cathode. Maximum power densities of 0.08, 0.15, and 0.26 W cm⁻² have been obtained at 500, 550 and 600 °C, respectively, using H₂ as fuel and ambient air as oxidant.     

Internal shorting and fuel loss of a low temperature solid oxide fuel cell with SDC electrolyte

A solid oxide fuel cell with Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte of 10 μm in thickness and Ni–SDC anode of 15 μm in thickness on a 0.8 mm thick Ni–YSZ cermet substrate was fabricated by tape casting, screen printing and co-firing. A composite cathode, 75 wt.% Sm_0.5Sr_0.5CoO₃ (SSCo) + 25 wt.% SDC, approximately 50 μm in thickness, was printed on the co-fired half-cell, and sintered at 950 °C. The cell showed a high electrochemical performance at temperatures ranging from 500 to 650 °C. Peak power density of 545 mW cm⁻² at 600 °C was obtained. However, the cell exhibited severe internal shorting due to the mixed conductivity of the SDC electrolyte. Both the amount of water collected from the anode outlet and the open circuit voltage (OCV) indicated that the internal shorting current could reach 0.85 A cm⁻² or more at 600 °C. Zr content inclusions were found at the surface and in the cross-section of the SDC electrolyte, which could be one of the reasons for reduced OCV and oxygen ionic conductivity. Fuel loss due to internal shorting of the thin SDC electrolyte cell becomes a significant concern when it is used in applications requiring high fuel utilization and electrical efficiency.