La_(0.5−x)ScxSr_(0.5)MnO_(3−δ)cathodes for proton-conducting solid oxide fuel cells:Taking advantage of the secondary phase

Designing high-performance cathodes is crucial for proton-conducting solid oxide fuel cells(H-SOFCs),as the cathode heavily influences cell performance.Although manganate cathodes exhibit superior stability and thermal compatibility,their poor cathode performance at intermediate temperatures renders them unsuitable for H-SOFC applications.To address this issue,Sc is utilized as a dopant to modify the traditional La_(0.5)ScxSr_(0.5)MnO_(3) cathode at the La site.Although the solubility of Sc at the La site is restricted to 2.5%,this modest quantity of Sc doping can improve the material's oxygen and proton transport capabilities,hence improving cathode and fuel cell performance.Furthermore,when the doping concentration exceeds 2.5%,the secondary phase ScMnO3 forms in situ,resulting in La_(0.475)Sc_(0.025)Sr_(0.5)MnO_(3)(LScSM)+ScMnO_(3) nanocomposites.Although the secondary phase is often considered undesirable,the high protonation capacity of ScMnO_(3) can compensate for the low proton diffusion ability of LScSM.These two phases complement each other to provide high-performance cathodes.The nominal La_(0.4)Sc_(0.1)Sr_(0.5)MnO_(3) is the optimal composition,which takes advantage of the excellent electronic conductivity and fast oxygen diffusion rates of LScSM,as well as the good proton diffusion capacity of ScMnO_(3),to produce a high fuel cell output of 1529 mW·cm−2 at 700°C.Furthermore,the fuel cell exhibited good operational stability under working conditions,indicating that La_(0.4)Sc_(0.1)Sr_(0.5)MnO_(3) is a viable cathode choice for H-SOFCs.

Manipulating Nb-doped SrFeO_(3−δ)with excellent performance for proton-conducting solid oxide fuel cells

Nb-doped SrFeO_(3−δ)(SFO)is used as a cathode in proton-conducting solid oxide fuel cells(H-SOFCs).First-principles calculations show that the SrFe0.9Nb0.1O_(3−δ)(SFNO)cathode has a lower energy barrier in the cathode reaction for H-SOFCs than the Nb-free SrFeO_(3−δ)cathode.Subsequent experimental studies show that Nb doping substantially enhances the performance of the SrFeO_(3−δ)cathode.Then,oxygen vacancies(VO)were introduced into SFNO using the microwave sintering method,further improving the performance of the SFNO cathode.The mechanism behind the performance improvement owing to VO was revealed using first-principles calculations,with further optimization of the SFNO cathode achieved by developing a suitable wet chemical synthesis route to prepare nanosized SFNO materials.This method significantly reduces the grain size of SFNO compared with the conventional solid-state reaction method,although the solid-state reaction method is generally used for preparing Nb-containing oxides.As a result of defect engineering and synthesis approaches,the SFNO cathode achieved an attractive fuel cell performance,attaining an output of 1764 mW·cm−2 at 700℃ and operating for more than 200 h.The manipulation of Nb-doped SrFeO_(3−δ)can be seen as a“one stone,two birds”strategy,enhancing cathode performance while retaining good stability,thus providing an interesting approach for constructing high-performance cathodes for H-SOFCs.

Recent progresses in the development of tubular segmented-in-series solid oxide fuel cells:Experimental and numerical study

Solid oxide fuel cells(SOFCs)have attracted a great deal of interest because they have the highest efficiency without using any noble metal as catalysts among all the fuel cell technologies.However,traditional SOFCs suffer from having a higher volume,current leakage,complex connections,and difficulty in gas sealing.To solve these problems,Rolls-Royce has fabricated a simple design by stacking cells in series on an insulating porous support,resulting in the tubular segmented-in-series solid oxide fuel cells(SIS-SOFCs),which achieved higher output voltage.This work systematically reviews recent advances in the structures,preparation methods,perform-ances,and stability of tubular SIS-SOFCs in experimental and numerical studies.Finally,the challenges and future development of tubular SIS-SOFCs are also discussed.The findings of this work can help guide the direction and inspire innovation of future development in this field.

Boosting oxygen reduction activity and CO_(2) resistance on bismuth ferrite-based perovskite cathode for low-temperature solid oxide fuel cells below 600℃

Developing efficient and stable cathodes for low-temperature solid oxide fuel cells(LT-SOFCs) is of great importance for the practical commercialization.Herein,we propose a series of Sm-modified Bi_(0.7-x)Sm_xSr_(0.3)FeO_(3-δ) perovskites as highly-active catalysts for LT-SOFCs.Sm doping can significantly enhance the electrocata lytic activity and chemical stability of cathode.At 600℃,Bi_(0.675)Sm_(0.025)Sr_(0.3)FeO_(3-δ)(BSSF25) cathode has been found to be the optimum composition with a polarization resistance of 0.098 Ω cm^2,which is only around 22.8% of Bi_(0.7)Sr_(0.3)FeO_(3-δ)(BSF).A full cell utilizing BSSF25 displays an exceptional output density of 790 mW cm^(-2),which can operate continuously over100 h without obvious degradation.The remarkable electrochemical performance observed can be attributed to the improved O_(2) transport kinetics,superior surface oxygen adsorption capacity,as well as O_(2)p band centers in close proximity to the Fermi level.Moreover,larger average bonding energy(ABE) and the presence of highly acidic Bi,Sm,and Fe ions restrict the adsorption of CO_(2) on the cathode surface,resulting in excellent CO_(2) resistivity.This work provides valuable guidance for systematic design of efficient and durable catalysts for LT-SOFCs.

A high-entropy spinel ceramic oxide as the cathode for proton-conducting solid oxide fuel cells

A high-entropy ceramic oxide is used as the cathode for the first time for proton-conducting solid oxide fuel cells(H-SOFCs).The Fe_(0.6)Mn_(0.6)Co_(0.6)Ni_(0.6)Cr_(0.6)O_(4)(FMCNC)high-entropy spinel oxide has been successfully prepared,and the in situ chemical stability test demonstrates that the FMCNC material has good stability against CO_(2).The first-principles calculation indicates that the high-entropy structure enhances the properties of the FMCNC material that surpasses their individual components,leading to lower O_(2)adsorption energy for FMCNC than that for the individual components.The HSOFC using the FMCNC cathode reaches an encouraging peak power density(PPD)of 1052 mW·cm^(-2)at 700℃,which is higher than those of the H-SOFCs reported recently.Additional comparison was made between the high-entropy FMCNC cathode and the traditional Mn_(1.6)Cu_(1.4)O_(4)(MCO)spinel cathode without the high-entropy structure,revealing that the formation of the high-entropy material allows the enhanced protonation ability as well as the movement of the O p-band center closer to the Fermi level,thus improving the cathode catalytic activity.As a result,the high-entropy FMCNC has a much-decreased polarization resistance of 0.057Ω·cm^(2)at 700℃,which is half of that for the traditional MCO spinel cathode without the high-entropy design.The excellent performance of the FMCNC cell indicates that the high-entropy design makes a new life for the spinel oxide as the cathode for HSOFCs,offering a novel and promising route for the development of high-performance materials for H-SOFCs.

High-performance proton-conducting solid oxide fuel cells using the first-generation Sr-doped LaMnO_(3) cathode tailored with Zn ions

Sr-doped LaMnO_(3)(LSM)which is the firstgeneration cathode for solid oxide fuel cells(SOFC;)has been tailored with Zn ions,aiming to achieve improved protonation ability for proton-conducting SOFCs(H-SOFCs).The new Sr and Zn co-doped LaMnO_(3)(LSMZ)can be successfully synthesized.The first-principle studies indicate that the LSMZ improves the protonation of LSM and decreases the barriers for oxygen vacancy formation,leading to high performance of the LSMZ cathode-based cells.The proposed LSMZ cell shows the highest fuel cell performance among ever reported LSMbased H-SOFCs.In addition,the superior fuel cell performance does not impair its stability.LSMZ is stable against CO_(2),as demonstrated by both in-situ CO_(2)corrosion tests and the first-principles calculations,leading to good long-term stability of the cell.The Zn-doping strategy for the traditional LSM cathode with high performance and good stability brings back the LSM cathode to intermediate temperatures and paves a new way for the research on the LSM-based materials as cathodes for SOFCs.

Tailoring Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)with Sc as a new single-phase cathode for proton-conducting solid oxide fuel cells

Sc-doped Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)(SFMSc)was successfully synthesized by partially substituting Mo in Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)(SFM)with Sc,resulting in a higher proton diffusion rate in the resultant SFMSc sample.Theoretical calculations showed that doping Sc into SFM lowered the oxygen vacancy formation energy,reduced the energy barrier for proton migration in the oxide,and increased the catalytic activity for oxygen reduction reaction.Next,a proton-conducting solid oxide fuel cell(H-SOFC)with a single-phase SFMSc cathode demonstrated significantly higher cell performance than that of cell based on an Sc-free SFM cathode,achieving 1258 mW cm^(−2)at 700℃.The performance also outperformed that of many other H-SOFCs based on single-phase cobalt-free cathodes.Furthermore,no trade-off between fuel cell performance and material stability was observed.The SFMSc material demonstrated good stability in both the CO_(2)-containing atmosphere and the fuel cell application.The combination of high performance and outstanding stability suggests that SFMSc is an excellent cathode material for H-SOFCs.

Successful preparation of BaCo_(0.5)Fe_(0.5)O_(3–δ)cathode oxide by rapidly cooling allowing for high-performance proton-conducting solid oxide fuel cells

A pure phase BaCo_(0.5)Fe_(0.5)O_(3–δ)(BCF),which cannot be obtained before,is successfully prepared in this study by using the calcination method with a rapid cooling procedure.The successful preparation of BCF allows the evaluation of this material as a cathode for proton-conducting solid oxide fuel cells(H-SOFCs)for the first time.An H-SOFC using the BCF cathode achieves an encouraging fuel cell performance of 2012 mW·cm–2 at 700,two℃-fold higher than that of a similar cell using the classical high-performance Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ)(BSCF)cathode.First-principles calculations reveal the mechanism for the performance enhancement,indicating that the new BCF cathode significantly lowers the energy barriers in the oxygen reduction reaction(ORR)compared with the BSCF cathode.Therefore,improved cathode performance and fuel cell output are obtained for the BCF cell.The fuel cell using the BCF cathode also shows excellent long-term stability that can work stably for nearly 900 h without noticeable degradations.The fuel cell performance and long-term stability of the current BCF cell are superior to most of the H-SOFCs reported in previous reports,suggesting that BCF is a promising cathode for H-SOFCs.

Investigation and optimization of high-valent Ta-doped SrFeO_(3-δ)as air electrode for intermediate-temperature solid oxide fuel cells

To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells(ITSOFCs),10mol%Ta5+doped in the B site of strontium ferrite perovskite oxide(SrTa_(0.1)Fe_(0.9)O_(3-δ),STF)is investigated and optimized.The effects of Ta^(5+)doping on structure,transition metal reduction,oxygen nonstoichiometry,thermal expansion,and electrical performance are evaluated systematically.Via 10mol%Ta^(5+)doping,the thermal expansion coefficient(TEC)decreased from 34.1×10^(-6)(SrFeO_(3-δ))to 14.6×10^(-6) K^(-1)(STF),which is near the TEC of electrolyte(13.3×10^(-6) K^(-1) for Sm_(0.2)Ce_(0.8)O_(1.9),SDC),indicates excellent thermomechanical compatibility.At 550-750℃,STF shows superior oxygen vacancy concentrations(0.262 to 0.331),which is critical in the oxygen-reduction reaction(ORR).Oxygen temperature-programmed desorption(O_(2)-TPD)indicated the thermal reduction onset temperature of iron ion is around 420℃,which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves.At 600℃,the STF electrode shows area-specific resistance(ASR)of 0.152Ω·cm^(2) and peak power density(PPD)of 749 mW·cm^(-2).ORR activity of STF was further improved by introducing 30wt%Sm_(0.2)Ce_(0.8)O_(1.9)(SDC)powder,STF+SDC composite cathode achieving outstanding ASR value of 0.115Ω·cm2 at 600℃,even comparable with benchmark cobalt-containing cathode,Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)(BSCF).Distribution of relaxation time(DRT)analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode.At 650℃,STF+SDC composite cathode achieving an outstanding PPD of 1117 mW·cm^(-2).The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.

Lattice Boltzmann simulation study of anode degradation in solid oxide fuel cells during the initial aging process

For present solid oxide fuel cells(SOFCs),rapid performance degradation is observed in the initial aging process,and the dis-cussion of the degradation mechanism necessitates quantitative analysis.Herein,focused ion beam-scanning electron microscopy was em-ployed to characterize and reconstruct the ceramic microstructures of SOFC anodes.The lattice Boltzmann method(LBM)simulation of multiphysical and electrochemical processes in the reconstructed models was performed.Two samples collected from industrial-size cells were characterized,including a reduced reference cell and a cell with an initial aging process.Statistical parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference cell.The LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process,and the electrochemical reactions spread to the support layer in the aged cell.The microstructural and activity de-gradations are attributed to Ni migration and coarsening.

Taking advantage of Li-evaporation in LiCoO_(2) as cathode for proton-conducting solid oxide fuel cells

LiCoO_(2),a widely used electrode material for Li-ion batteries,was found to be suitable as a cathode material for proton-conducting solid oxide fuel cells(H-SOFCs).Although the evaporation of Li in LiCoO_(2) was detrimental to the Li-ion battery performance,the Li-evaporation was found to be beneficial for the H-SOFCs.The partial evaporation of Li in the LiCoO_(2) material preparation procedure led to the in-situ formation of the LiCoO_(2)+Co_(3)O_(4) composite.Compared to the cell using the pure phase LiCoO_(2) cathode that only generated moderate fuel cell performance,the H-SOFCs using the LiCoO_(2)+Co_(3)O_(4) cathode showed a high fuel cell performance of 1160 mW·cm^(-2) at 700℃,suggesting that the formation of Co_(3)O_(4) was critical for enhancing the performance of the LiCoO_(2) cathode.The first-principles calculation gave insights into the performance improvements,indicating that the in-situ formation of Co_(3)O_(4) due to the Li-evaporation in LiCoO_(2) could dramatically decrease the formation energy of oxygen vacancies that is essential for the high cathode performance.The evaporation of Li in LiCoO_(2),which is regarded as a drawback for the Li-ion batteries,is demonstrated to be advantageous for the H-SOFCs,offering new selections of cathode candidates for the H-SOFCs.

Tailoring cobalt-free La_(0.5)Sr_(0.5)FeO_(3-δ)cathode with a nonmetal cation-doping strategy for high-performance proton-conducting solid oxide fuel cells

A nonmetal doping strategy was exploited for the conventional La_(0.5)Sr_(0.5)FeO_(3-δ)(LSF)cathode,allowing high performance for proton-conducting solid oxide fuel cells(H-SOFCs).Unlike previous studies focusing on the utilization of metal oxides as dopants,phosphorus,which is a nonmetal element,was used as the cation dopant for LSF by partially replacing Fe ions to form the new La_(0.5)Sr_(0.5)Fe_(0.9)P_(0.1)O_(3-δ)(LSFP)compound.The H-SOFC using the LSFP cathode showed a two-fold peak power density as compared to that using the LSF cathode.Both experimental studies and first-principle calculations were used to unveil the mechanisms for the high performance of the LSFP cells.

Attempted preparation of La_(0.5)Ba_(0.5)MnO_(3-δ) leading to an in-situ formation of manganate nanocomposites as a cathode for proton-conducting solid oxide fuel cells

A La_(0.5)Ba_(0.5)MnO_(3-δ) oxide was prepared using the sol-gel technique.Instead of a pure phase,La_(0.5)Ba_(0.5)MnO_(3-δ) was discovered to be a combination of La_(0.7)Ba_(0.3)MnO_(3-δ) and BaMnO_(3).The in-situ production of La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposites enhanced the oxygen vacancy(Vo)formation compared to single-phase La_(0.7)Ba_(0.3)MnO_(3-δ) or BaMnO_(3),providing potential benefits as a cathode for fuel cells.Subsequently,La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposites were utilized as the cathode for proton-conducting solid oxide fuel cells(H-SOFCs),which significantly improved cell performance.At 700 C,H-SOFC with a La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposite cathode achieved the highest power density(1504 mW·cm^(-2))yet recorded for H-SOFCs with manganate cathodes.This performance was much greater than that of single-phase La_(0.7)Ba_(0.3)MnO_(3-δ)or BaMnO_(3) cathode cells.In addition,the cell demonstrated excellent working stability.First-principles calculations indicated that the La_(0.7)Ba_(0.3)MnO_(3-δ)/BaMnO_(3) interface was crucial for the enhanced cathode performance.The oxygen reduction reaction(ORR)free energy barrier was significantly lower at the La_(0.7)Ba_(0.3)MnO_(3-δ)/BaMnO_(3) interface than that at the La_(0.7)Ba_(0.3)MnO_(3-δ) or BaMnO_(3) surfaces,which explained the origin of high performance and gave a guide for the construction of novel cathodes for H-SOFCs.

A real proton-conductive,robust,and cobalt-free cathode for proton-conducting solid oxide fuel cells with exceptional performance

The development of proton,oxygen-ion,and electron mixed conducting materials,known as triple-conduction materials,as cathodes for proton-conducting solid oxide fuel cells(H-SOFCs)is highly desired because they can increase fuel cell performance by extending the reaction active area.Although oxygen-ion and electron conductions can be measured directly,proton conduction in these oxides is usually estimated indirectly.Because of the instability of cathode materials in a reducing environment,direct measurement of proton conduction in cathode oxide is difficult.The La0.8Sr0.2Sc0.5Fe0.5O3–δ(LSSF)cathode material is proposed for H-SOFCs in this study,which can survive in an H_(2)-containing atmosphere,allowing measurement of proton conduction in LSSF by hydrogen permeation technology.Furthermore,LSSF is discovered to be a unique proton and electron mixed-conductive material with limited oxygen diffusion capability that is specifically designed for H-SOFCs.The LSSF is an appealing cathode choice for H-SOFCs due to its outstanding CO_(2)tolerance and matched thermal expansion coefficient,producing a record-high performance of 2032 mW cm^(−2)at 700℃and good long-term stability under operational conditions.The current study reveals that a new type of proton–electron mixed conducting cathode can provide promising performance for H-SOFCs,opening the way for developing high-performance cathodes.

Entropy engineering design of high-performing lithiated oxide cathodes for proton-conducting solid oxide fuel cells

A new medium entropy material LiCo_(0.25)Fe_(0.25)Mn_(0.2)5Ni_(0.2)5O_(2)(LCFMN)is proposed as a cathode for proton-conducting solid oxide fuel cells(H-SOFCs).Unlike traditional LiXO_(2)(X=Co,Fe,Mn,Ni)lithiated oxides,which have issues like phase impurity,poor chemical compatibility,or poor fuel cell performance,the new LCFMN material mitigates these problems,allowing for the successful preparation of pure phase LCFMN with good chemical and thermal compatibility to the electrolyte.Furthermore,the entropy engineering strategy is found to weaken the covalence bond between the metal and oxygen in the LCFMN lattice,favoring the creation of oxygen vacancies and increasing cathode activity.As a result,the H-SOFC with the LCFMN cathode achieves an unprecedented fuel cell output of 1803 mW·cm^(−2)at 700℃,the highest ever reported for H-SOFCs with lithiated oxide cathodes.In addition to high fuel cell performance,the LCFMN cathode permits stable fuel cell operation for more than 450 h without visible degradation,demonstrating that LCFMN is a suitable cathode choice for H-SOFCs that combining high performance and good stability.

Nanostructuring the electronic conducting La_(0.8)Sr_(0.2)MnO_(3-δ) cathode for high-performance in proton-conducting solid oxide fuel cells below 600℃

Proton-conducting oxides offer a promising electrolyte solution for intermediate temperature solid oxide fuel cells（SOFCs） due to their high conductivity and low activation energy. However, the lower operation temperature leads to a reduced cathode activity and thus a poorer fuel cell performance. La_（0.8）Sr_（0.2）MnO_（3-δ）（LSM） is the classical cathode material for high-temperature SOFCs, which lack features as a proper SOFC cathode material at intermediate temperatures.Despite this, we here successfully couple nanostructured LSM cathode with proton-conducting electrolytes to operate below600℃ with desirable SOFC performance. Inkjet printing allows depositing nanostructured particles of LSM on Y-doped Ba ZrO_3（BZY） backbones as cathodes for proton-conducting SOFCs, which provides one of the highest power output for the BZY-based fuel cells below 600 ℃. This somehow changes the common knowledge that LSM can be applied as a SOFC cathode materials only at high temperatures（above 700 ℃）.

From concept to commercialization:A review of tubular solid oxide fuel cell technology

The reduced sealing difficulty of tubular solid oxide fuel cells(SOFCs)makes the stacking of tubular cell groups relatively easy,and the thermal stress constraints during stack operation are smaller,which helps the stack to operate stably for a long time.The special design of tubular SOFC structures can completely solve the problem of high-temperature sealing,especially in the design of multiple single-cell series integrated into one tube,where each cell tube is equivalent to a small electric stack,with unique characteristics of high voltage and low current output,which can significantly reduce the ohmic polarization loss of tubular cells.This paper provides an overview of typical tubular SOFC structural designs both domestically and internationally.Based on the geometric structure of tubular SOFCs,they can be divided into bamboo tubes,bamboo flat tubes,single-section tubes,and single-section flat tube structures.Meanwhile,this article provides an overview of commonly used materials and preparation methods for tubular SOFCs,including commonly used materials and preparation methods for support and functional layers,as well as a comparison of commonly used preparation methods for microtubule SOFCs,It introduced the three most important parts of building a fuel cell stack:manifold,current collector,and ceramic adhesive,and also provided a detailed introduction to the power generation systems of different tubular SOFCs,Finally,the development prospects of tubular SOFCs were discussed.

Recovery of Solid Oxide Fuel CellWaste Heat by Thermoelectric Generators and AlkaliMetal Thermoelectric Converters

A Solid Oxide Fuel Cell(SOFC)is an electrochemical device that converts the chemical energy of a substance into electrical energy through an oxidation-reduction mechanism.The electrochemical reaction of a solid oxide fuel cell(SOFC)generates heat,and this heat can be recovered and put to use in a waste heat recovery system.In addition to preheating the fuel and oxidant,producing steam for industrial use,and heating and cooling enclosed rooms,this waste heat can be used for many more productive uses.The large waste heat produced by SOFCs is a worry that must be managed if they are to be adopted as a viable option in the power generation business.In light of these findings,a novel approach to SOFC waste heat recovery is proposed.The SOFC is combined with a“Thermoelectric Generator and an Alkali Metal Thermoelectric Converter(TG-AMTC)”to transform the excess heat generated by both the SOFC and the TG-AMTC.The proposed TG-AMTC is evaluated using a number of performance indicators including power density,operating temperature,heat recovery rate,exergetic efficiency,energy efficiency,and recovery time.The experimental results state that TG-AMTC has provided an exergetic efficiency,energetic efficiency,and recovery time of 97%,98%,and 23%,respectively.The study proves that the proposed TG-AMTC for SOFC is an efficient method of recovering waste heat.

Ni doped La_(0.6)Sr_(0.4)FeO_(3-δ) symmetrical electrode for solid oxide fuel cells

The conventional Ni cermet anode suffers from severe carbon deposition and sulfur poisoning when fossil fuels are used. Alternative anode materials are desired for high performance hydrocarbon fuel solid oxide fuel cells （SOFCs）. We report the rational design of a very active Ni doped La0.6Sr0.4FeO3‐δ（LSFN） electrode for hydrocarbon fuel SOFCs. Homogeneously dispersed Ni‐Fe alloy nanoparticles were in situ extruded onto the surface of the LSFN particles during the operation of the cell. Sym‐metric SOFC single cells were prepared by impregnating a LSFN precursor solution onto a YSZ （yt‐tria stabilized zirconia） monolithic cell with a subsequent heat treatment. The open circuit voltage of the LSFN symmetric cell reached 1.18 and 1.0 V in humidified C3H8 and CH4 at 750？？, respective‐ly. The peak power densities of the cells were 400 and 230 mW/cm2 in humidified C3H8 and CH4, respectively. The electrode showed good stability in long term testing, which revealed LSFN has good catalytic activity for hydrocarbon fuel oxidation.

Samaria-doped Ceria Modified Ni/YSZ Anode for Direct Methane Fuel in Tubular Solid Oxide Fuel Cells by Impregnation Method

A porous NiO/yttria-stabilized zirconia was prepared by gel casting technique. anode substrate for tubular solid oxide fuel cells Nano-scale samaria-doped ceria （SDC） particles were formed onto the anode substrate to modify the anode microstructure by the impregnation of solution of Sm（NO3）3 and Ce（NO3）3. Electrochemical impedance spectroscopy, current-voltage and current-powder curves of the cells were measured using an electrochemical workstation. Scanning electron microcopy was used to observe the microstructure. The results indicate that the stability of the performance of the cell operated on humidified methane can be significantly improved by incorporating the nano-structured SDC particles, compared with the unmodified cell. This verifies that the coated SDC electrodes are very effective in suppressing catalytic carbon formation by blocking methane from approaching the Ni, which is catalytically active towards methane pyrolysis. In addition, it was found that a small amount of deposited carbon is beneficial to the performance of the anode. The cell showed a peak power density of 225 mW/cm^2 when it was fed with H2 fuel at 700 ℃, but the power density increased to 400 mW/cm^2 when the fuel was switched from hydrogen to methane at the same flow rate. Methane conversion achieved about 90%, measured by gas chromatogram with a 10.0 mL/min flow rate of fuel at 700 ℃. Although the carbon deposition was not suppressed absolutely, some deposited carbon was beneficial for performance improvement.