This study addresses the challenge of high sintering temperatures in proton-conducting fuel cells(PCFCs)with BaCeO_(3)-doped electrolytes.We demonstrate that 1 mol%copper(Cu)doping at the B-site of BaCe_(0.7)Zr_(0.1)(...This study addresses the challenge of high sintering temperatures in proton-conducting fuel cells(PCFCs)with BaCeO_(3)-doped electrolytes.We demonstrate that 1 mol%copper(Cu)doping at the B-site of BaCe_(0.7)Zr_(0.1)(Dy_(0.1)|Yb_(0.1))_(0.2)O_(3-δ)(BCZDYb)improves sintering behavior,enabling densification at1400℃.However,Cu doping disrupts stoichiometry,creating barium vacancies and reducing protonaccepting cations,affecting overall conductivity.This mechanism is confirmed through density functional theory(DFT)calculations and various experimental techniques,including crystal structure analysis using X-ray diffraction(XRD)and morphology and elemental analysis via field emission scanning electron microscopy(FESEM)and energy-dispersive X-ray spectroscopy(EDS).Electrochemical measurements are performed using the electrochemical impedance spectroscopy(EIS).The ionic conductivity of1 mol%Cu-doped BCZDYb(BCZDYb-1)is 1.49×10^(-2)S cm^(-1)at 650℃,which is~3.58 times higher than that of BCZDYb sintered at 1200℃.The BCZDYb-1 exhibits~16 times higher grain boundary conductivity when sintered at 1400℃,compared to undoped BCZDYb.The single cell employing BCZDYb-1 as the electrolyte achieved a power density of~606 mW cm^(-2)at 550℃.These results indicate that a controlled amount of Cu doping can enhance densification while maintaining high ionic co nductivity,making it suitable for practical applications in PCFCs operating at lower temperatures.展开更多
Complex oxides are an important class of materials with enormous potential for electrochemical appli-cations.Depending on their composition and structure,such complex oxides can exhibit either a single conductivity(ox...Complex oxides are an important class of materials with enormous potential for electrochemical appli-cations.Depending on their composition and structure,such complex oxides can exhibit either a single conductivity(oxygen-ionic or protonic,or n-type,or p-type electronic)or a combination thereof gener-ating distinct dual-conducting or even triple-conducting materials.These properties enable their use as diverse functional materials for solid oxide fuel cells,solid oxide electrolysis cells,permeable membranes,and gas sensors.The literature review shows that the field of solid oxide materials and related electro-chemical cells has a significant level of research engagement,with over 8,000 publications published since 2020.The manual analysis of such a large volume of material is challenging.However,by examining the review articles,it is possible to identify key patterns,recent achievements,prospects,and remaining obstacles.To perform such an analysis,the present article provides,for the first time,a comprehensive summary of previous review publications that have been published since 2020,with a special focus on solid oxide materials and electrochemical systems.Thus,this study provides an important reference for researchers specializing in the fields of solid state ionics,high-temperature electrochemistry,and energyconversiontechnologies.展开更多
Protonic ceramic fuel cells(PCFCs)have been attracting increasing attention because of their advances in high-efficiency power generation in an intermediate-temperature range,as compared to the high-temperature solid ...Protonic ceramic fuel cells(PCFCs)have been attracting increasing attention because of their advances in high-efficiency power generation in an intermediate-temperature range,as compared to the high-temperature solid oxide fuel cells(SOFCs).The greatest difference between PCFCs and SOFCs is the specific requirement of protonic(H+)conductivity at the PCFC cathode,in addition to the electronic(e^(-))and oxide-ion(O^(2-))conductivity.The development of a triple H^(+)/e^(-)/O^(2-)conductor for PCFC cathode is still challenging.Thus,the most-widely used cathode material is based on the mature e^(-)/O^(2-)conductor.However,this leads to insufficient triple phase boundary(TPB),i.e.,reaction area.Herein,an efficient strategy that uses a~100 nm-thick proton conductive functional layer(La_(0.5)Sr_(0.5)CoO_(3-δ),LSC55)in-between the typical La_(0.8)Sr_(0.2)CoO_(3-δ)cathode(a mature e-/O^(2-)conductor,LS C 82)and B aZr_(0.4)Ce_(0.4)Y_(0.1)Yb_(0.)1O_(3-δ)elec trolyte(11 mm in diameter,20μm in thickness)is proposed to significantly enhance the reaction area.Reasonably,the ohmic resistance and polarization resistance are both decreased by 47%and 62%,respectively,compared with that of PCFCs without the functional layer.The power density of the PCFC with such a functional layer can be raised by up to 2.24 times,superior to those described in previous reports.The enhanced PCFC performances are attributed to the well-built TPB and enhanced reaction area via the functional layer engineering strategy.展开更多
Highly active and stable electrocatalysts are mandatory for developing high-performance and longlasting fuel cells.The current study demonstrates a high oxygen reduction reaction(ORR)electrocatalytic activity of a nov...Highly active and stable electrocatalysts are mandatory for developing high-performance and longlasting fuel cells.The current study demonstrates a high oxygen reduction reaction(ORR)electrocatalytic activity of a novel spinel-structured LaFe_(2)O_(4)via a self-doping strategy.The LaFe_(2)O_(4)demonstrates excellent ORR activity in a protonic ceramic fuel cell(PCFC)at temperature range of 350-500℃.The high ORR activity of LaFe_(2)O_(4)is mainly attributed to the facile release of oxide and proton ions,and improved synergistic incorporation abilities associated with interplay of multivalent Fe^(3+)/Fe^(2+)and La^(3+)ions.Using LaFe_(2)O_(4)as cathode over proton conducting BaZr_(0.4)Ce_(0.4)Y_(0.2)O_(3)(BZCY)electrolyte,the fuel cell has delivered a high-power density of 806 mW/cm^(2)operating at 500℃.Different spectroscopic and calculations methods such as UV-visible,Raman,X-ray photoelectron spectroscopy and density functional theory(DFT)calculations were performed to screen the potential application of LaFe_(2)O_(4)as cathode.This study would help in developing functional cobalt-free ORR electrocatalysts for low temperature-PCFCs(LT-PCFCs)and solid oxide fuel cells(SOFCs)applications.展开更多
Solid oxide fuel cells(SOFCs)and electrolysis cells(SOECs)are promising energy conversion devices,on whose basis green hydrogen energy technologies can be developed to support the transition to a carbon-free future.As...Solid oxide fuel cells(SOFCs)and electrolysis cells(SOECs)are promising energy conversion devices,on whose basis green hydrogen energy technologies can be developed to support the transition to a carbon-free future.As compared with oxygen-conducting cells,the operational temperatures of protonic ceramic fuel cells(PCFCs)and electrolysis cells(PCECs)can be reduced by several hundreds of degrees(down to low-and intermediatetemperature ranges of 400–700C)while maintaining high performance and efficiency.This is due to the distinctive characteristics of charge carriers for proton-conducting electrolytes.However,despite achieving outstanding lab-scale performance,the prospects for industrial scaling of PCFCs and PCECs remain hazy,at least in the near future,in contrast to commercially available SOFCs and SOECs.In this review,we reveal the reasons for the delayed technological development,which need to be addressed in order to transfer fundamental findings into industrial processes.Possible solutions to the identified problems are also highlighted.展开更多
Efforts to improve the performance of protonic ceramic fuel cells(PCFCs)have been hampered by the limited availability of cathode materials with high activity and durability.One potential approach to enhance electroca...Efforts to improve the performance of protonic ceramic fuel cells(PCFCs)have been hampered by the limited availability of cathode materials with high activity and durability.One potential approach to enhance electrocatalytic performance is by modifying the particle morphology of the cathode,which potentially reforms transport properties and active reaction sites.Herein,the configuration of cathode particles via controllable growth of cubes was used to ameliorate perovskite-related Pr_(1.5)Ba_(1.5)Cu_(3)O_(7)(PBC).The PBC particle geometry changes to a cube when the calcination temperature is switched from 900 to 950℃,exposing the{100}crystal facets on the surface.This gives rise to more surface oxygen vacancies and efficient Cu^(2+)-O-Cu^(3+)electron hopping transition paths,favoring high electrocatalytic activity with expeditious oxygen adsorption/activation and facilitating the oxygen reduction reaction(ORR)process.The particle-cubic PBC cathode assembled at 950℃(PBC-950)exhibited significantly enhanced performance,with a power output of 1982 mW·cm^(−2) and a polarization resistance(RP)of 0.028Ω·cm2 at 700℃ on a PCFC,outperforming other Co-based and Cu-based single-phase cathodes reported in the literature.Overall,the superior power and polarization performance,along with excellent durability over 200 h,suggest that PBC-950 is a promising alternative for PCFC cathodes.This study demonstrates the potential of controlling particle growth to design highly active electrodes with specialized properties,opening new avenues for material design in PCFCs and related electrocatalytic fields.展开更多
Obtaining high-performance cathodes is critical for protonic ceramic fuel cells(PCFCs),as cathode performance significantly impacts fuel cell performance.A full understanding of the interactions among the diverse prop...Obtaining high-performance cathodes is critical for protonic ceramic fuel cells(PCFCs),as cathode performance significantly impacts fuel cell performance.A full understanding of the interactions among the diverse properties of cathode materials would benefit cathode design.In this study,PrBaFe_(2)O_(6-δ)(PBF)was doped with various dopants,including cobalt(Co),Ni,Cu,Zn,and Mn.Experiments and first-principles calculations are used to study the key properties of dopant-modified PrBaFe_(2)O_(6-δ),including oxygen vacancy(VO)creation,hydration ability,proton mobility,and oxygen reduction reaction(ORR)activity.There is no perfect dopant that can improve every property to its full potential.Instead,different dopants can impact different properties of the material.Co-dopant has the best cathode performance since it balances the material’s instinctive properties,even though it does not provide a significant advantage in the formation of VO.PCFC utilizing Co-doped PrBaFe_(2)O_(6-δ)cathode has a high performance of 1680 mW·cm^(-2) at 700℃,which is greater than that of the other dopant-tailored PrBaFe_(2)O_(6-δ)cathodes reported in this study and is one of the largest ever recorded for PrBaFe_(2)O_(6-δ)-based cathodes for PCFCs.Co-doped PrBaFe_(2)O_(6-δ)cathode is further demonstrated to be robust,with excellent operational stability.This study not only provides a potential cathode candidate for PCFCs but also suggests an intriguing approach to cathode design by carefully examining and balancing different vital properties of the material.展开更多
Ammonia is an exceptional fuel for solid oxide fuel cells(SOFCs),because of the high content of hydrogen and the advantages of carbon neutrality.However,the challenge lies in its unsatisfactory performance at intermed...Ammonia is an exceptional fuel for solid oxide fuel cells(SOFCs),because of the high content of hydrogen and the advantages of carbon neutrality.However,the challenge lies in its unsatisfactory performance at intermediate temperatures(500‒600℃),impeding its advancement.An electrolyte-supported proton-ceramic fuel cell(PCFC)was fabricated employing BaZr_(0.1)Ce_(0.7)Y_(0.2)O_(3)–δ(BZCY)as the electrolyte and Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3)–δ(BSCF)as the cathode.In this study,the performance of PCFC using NH_(3)as fuel within an operating temperature range of 500‒700℃ was improved by adding an M(Ni,Ru)/CeO_(2)catalyst layer to reconstruct the anode surface.The electrochemical performance of direct ammonia PCFC(DA-PCFC)were improved to different extents.Compared to H_(2)as fuel,the degradation ratio of peak power densities(PPDs)of Ni/CeO_(2)-loaded PCFC fueled with NH_(3)decreased at 700‒500℃,with a decrease to 13.3%at 700℃ and 30.7%at 500℃.The findings indicate that Ru-based catalysts have a greater promise for direct ammonia SOFCs(DA-SOFCs)at operating temperatures below 600℃.However,the enhancement effect becomes less significant above 600℃ when compared to Ni-based catalysts.展开更多
Current perovskite oxide electrolytes,i.e.,acceptor-doped Ba(Ce,Zr)O_(3-δ),exhibit proton conductivity ranging from 10^(-3) to 10^(-2) S cm^(−1) at 600℃ for protonic ceramic fuel cells(PCFCs),which rely on the struc...Current perovskite oxide electrolytes,i.e.,acceptor-doped Ba(Ce,Zr)O_(3-δ),exhibit proton conductivity ranging from 10^(-3) to 10^(-2) S cm^(−1) at 600℃ for protonic ceramic fuel cells(PCFCs),which rely on the structural defects.However,bulk doping and sintering restrict these oxides to possess higher ionic conductivity.New-generation PCFCs with alternative ion conduction mechanism need to be developed.This study presents a novel approach to realize high proton conduction along a fluorite oxide-ion conductor gadolinium-doped ceria(GDC:Gd_(0.1)Ce_(0.9)O_(2-δ))by electrochemical proton injection via a fuel cell process.A high protonic conductivity of 0.158 S cm^(−1) has been achieved.This fuel cell employing a 400-μm-thick GDC electrolyte delivered a peak power output close to 1,000 mW cm^(−2) at 500℃.Proton conduction is verified by electrochemical impedance spectroscopy,proton filtering cell and isotopic effect,and so on.Proton injection into GDC after fuel cell testing is clarified by x-ray photoelectron spectroscopy,Raman spectra,^(1)H solid-state nuclear magnetic resonance spectra,and so on.Furthermore,a synergistic mechanism involving both surface proton conduction and bulk oxygen-ion migration is proposed by comparing electrochemical impedance spectroscopy with distribution of relaxation time results of GDC and pure ceria.This finding may provide new insights into the ion transport mechanism on fluorite oxides and open new avenues for advanced low-temperature PCFCs.展开更多
Slow oxygen reduction reaction(ORR)involving proton transport remains the limiting factor for electrochemical performance of proton-conducting cathodes.To further reduce the operating temperature of protonic ceramic f...Slow oxygen reduction reaction(ORR)involving proton transport remains the limiting factor for electrochemical performance of proton-conducting cathodes.To further reduce the operating temperature of protonic ceramic fuel cells(PCFCs),developing triple-conducting cathodes with excellent electrochemical performance is required.In this study,K-doped BaCo_(0.4)Fe_(0.4)Zr_(0.2)O_(3−δ)(BCFZ442)series were developed and used as the cathodes of the PCFCs,and their crystal structure,conductivity,hydration capability,and electrochemical performance were characterized in detail.Among them,Ba_(0.9)K_(0.1)Co_(0.4)Fe_(0.4)Zr_(0.2)O_(3−δ)(K10)cathode has the best electrochemical performance,which can be attributed to its high electron(e^(−))/oxygen ion(O^(2−))/H^(+)conductivity and proton uptake capacity.At 750℃,the polarization resistance of the K10 cathode is only 0.009Ω·cm^(2),the peak power density(PPD)of the single cell with the K10 cathode is close to 1 W·cm^(−2),and there is no significant degradation within 150 h.Excellent electrochemical performance and durability make K10 a promising cathode material for the PCFCs.This work can provide a guidance for further improving the proton transport capability of the triple-conducting oxides,which is of great significance for developing the PCFC cathodes with excellent electrochemical performance.展开更多
New two-layer Ruddlesden-Popper(RP)oxide La_(0.25)Sr_(2.75)FeNiO_(7-δ)(LSFN)in the combination of Sr_(3)Fe_(2)O_(7-δ) and La_(3)Ni_(2)O_(7-δ) was successfully synthesized and studied as the potential active single-...New two-layer Ruddlesden-Popper(RP)oxide La_(0.25)Sr_(2.75)FeNiO_(7-δ)(LSFN)in the combination of Sr_(3)Fe_(2)O_(7-δ) and La_(3)Ni_(2)O_(7-δ) was successfully synthesized and studied as the potential active single-phase and composite cathode for protonic ceramics fuel cells(PCFCs).LSFN with the tetragonal symmetrical structure(IMmmm)is confinned,and the co-existence of Fe^(3+)/Fe^(4+) and Ni^(3+)/Ni^(2+) couples is demonstrated by X-ray photoelectron spectrometer(XPS)analysis.The LSFN conductivity is apparently enhanced after Ni doping in Fe-site,and nearly three times those of Sr_(3)Fe_(2)O_(7-δ),which is directly related to the carrier concentration and conductor mechanism.Importantly,anode supported PCFCs using LSFN-BaZr_(0.1)Ce_(0.7)Y_(0.2)O_(3-δ)(LSFN-BZCY)composite cathode achieved high power density(426 mW·cm^(-2) at 650℃)and low electrode interface polarization resistance(0.26Ω·cm^(2)).Besides,distribution of relaxation time(DRT)function technology was further used to analyse the electrode polarization processes.The observed three peaks(Pl,P2,and P3)separated by DRT shifted to the high frequency region with the decreasing temperature,suggesting that the charge transfer at the electrode-electrolyte interfaces becomes more difficult at reduced temperatures.Preliminary results demonstrate that new two-layer RP phase LSFN can be a promising cathode candidate for PCFCs.展开更多
Protonic ceramic fuel cells(PCFCs)offer a convenient means for electrochemical conversion of chemical energy into electricity at intermediate temperatures with very high efficiency.Although BaCeO_(3)-and BaZrO_(3)-bas...Protonic ceramic fuel cells(PCFCs)offer a convenient means for electrochemical conversion of chemical energy into electricity at intermediate temperatures with very high efficiency.Although BaCeO_(3)-and BaZrO_(3)-based complex oxides have been positioned as the most promising PCFC electrolytes,the design of new protonic conductors with improved properties is of paramount importance.Within the present work,we studied transport properties of scandium-doped barium stannate(Sc-doped BaSnO_(3)).Our analysis included the fabrication of porous and dense BaSn_(1−x)Sc_(x)O_(3−δ)ceramic materials(0≤x≤0.37),as well as a comprehensive analysis of their total,ionic,and electronic conductivities across all the experimental conditions realized under the PCFC operation:both air and hydrogen atmospheres with various water vapor partial pressures(p(H2O)),and a temperature range of 500–900℃.This work reports on electrolyte domain boundaries of the undoped and doped BaSnO_(3)for the first time,revealing that pure BaSnO_(3)exhibits mixed ionic–electronic conduction behavior under both oxidizing and reducing conditions,while the Sc-doping results in the gradual improvement of ionic(including protonic)conductivity,extending the electrolyte domain boundaries towards reduced atmospheres.This latter property makes the heavilydoped BaSnO_(3)representatives attractive for PCFC applications.展开更多
基金supported by the National Key Research and Development Program of China(2021YFB4001400)the Cooperation Project of Shan-dong Energy Group Co.,Ltd.(20200871)supported by 111 Project 2.0(BP0618008).
文摘This study addresses the challenge of high sintering temperatures in proton-conducting fuel cells(PCFCs)with BaCeO_(3)-doped electrolytes.We demonstrate that 1 mol%copper(Cu)doping at the B-site of BaCe_(0.7)Zr_(0.1)(Dy_(0.1)|Yb_(0.1))_(0.2)O_(3-δ)(BCZDYb)improves sintering behavior,enabling densification at1400℃.However,Cu doping disrupts stoichiometry,creating barium vacancies and reducing protonaccepting cations,affecting overall conductivity.This mechanism is confirmed through density functional theory(DFT)calculations and various experimental techniques,including crystal structure analysis using X-ray diffraction(XRD)and morphology and elemental analysis via field emission scanning electron microscopy(FESEM)and energy-dispersive X-ray spectroscopy(EDS).Electrochemical measurements are performed using the electrochemical impedance spectroscopy(EIS).The ionic conductivity of1 mol%Cu-doped BCZDYb(BCZDYb-1)is 1.49×10^(-2)S cm^(-1)at 650℃,which is~3.58 times higher than that of BCZDYb sintered at 1200℃.The BCZDYb-1 exhibits~16 times higher grain boundary conductivity when sintered at 1400℃,compared to undoped BCZDYb.The single cell employing BCZDYb-1 as the electrolyte achieved a power density of~606 mW cm^(-2)at 550℃.These results indicate that a controlled amount of Cu doping can enhance densification while maintaining high ionic co nductivity,making it suitable for practical applications in PCFCs operating at lower temperatures.
文摘Complex oxides are an important class of materials with enormous potential for electrochemical appli-cations.Depending on their composition and structure,such complex oxides can exhibit either a single conductivity(oxygen-ionic or protonic,or n-type,or p-type electronic)or a combination thereof gener-ating distinct dual-conducting or even triple-conducting materials.These properties enable their use as diverse functional materials for solid oxide fuel cells,solid oxide electrolysis cells,permeable membranes,and gas sensors.The literature review shows that the field of solid oxide materials and related electro-chemical cells has a significant level of research engagement,with over 8,000 publications published since 2020.The manual analysis of such a large volume of material is challenging.However,by examining the review articles,it is possible to identify key patterns,recent achievements,prospects,and remaining obstacles.To perform such an analysis,the present article provides,for the first time,a comprehensive summary of previous review publications that have been published since 2020,with a special focus on solid oxide materials and electrochemical systems.Thus,this study provides an important reference for researchers specializing in the fields of solid state ionics,high-temperature electrochemistry,and energyconversiontechnologies.
基金financially supported by China Post-doctoral Science Foundation(No.2022M710856)Guangzhou Postdoctoral Research Project(No.62104380)+2 种基金the Outstanding Youth Project of Natural Science Foundation of Guangdong Province(No.2022B1515020020)the Funding by Science and Technology Projects in Guangzhou(Nos.202206050003 and 202201010603)Guangdong Engineering Technology Research Center for Hydrogen Energy and Fuel Cells。
文摘Protonic ceramic fuel cells(PCFCs)have been attracting increasing attention because of their advances in high-efficiency power generation in an intermediate-temperature range,as compared to the high-temperature solid oxide fuel cells(SOFCs).The greatest difference between PCFCs and SOFCs is the specific requirement of protonic(H+)conductivity at the PCFC cathode,in addition to the electronic(e^(-))and oxide-ion(O^(2-))conductivity.The development of a triple H^(+)/e^(-)/O^(2-)conductor for PCFC cathode is still challenging.Thus,the most-widely used cathode material is based on the mature e^(-)/O^(2-)conductor.However,this leads to insufficient triple phase boundary(TPB),i.e.,reaction area.Herein,an efficient strategy that uses a~100 nm-thick proton conductive functional layer(La_(0.5)Sr_(0.5)CoO_(3-δ),LSC55)in-between the typical La_(0.8)Sr_(0.2)CoO_(3-δ)cathode(a mature e-/O^(2-)conductor,LS C 82)and B aZr_(0.4)Ce_(0.4)Y_(0.1)Yb_(0.)1O_(3-δ)elec trolyte(11 mm in diameter,20μm in thickness)is proposed to significantly enhance the reaction area.Reasonably,the ohmic resistance and polarization resistance are both decreased by 47%and 62%,respectively,compared with that of PCFCs without the functional layer.The power density of the PCFC with such a functional layer can be raised by up to 2.24 times,superior to those described in previous reports.The enhanced PCFC performances are attributed to the well-built TPB and enhanced reaction area via the functional layer engineering strategy.
基金Project supported by the National Natural Science Foundation of China(51772080,11604088,51706093)Jiangsu Provence Talent Program(JSSCRC2021491)。
文摘Highly active and stable electrocatalysts are mandatory for developing high-performance and longlasting fuel cells.The current study demonstrates a high oxygen reduction reaction(ORR)electrocatalytic activity of a novel spinel-structured LaFe_(2)O_(4)via a self-doping strategy.The LaFe_(2)O_(4)demonstrates excellent ORR activity in a protonic ceramic fuel cell(PCFC)at temperature range of 350-500℃.The high ORR activity of LaFe_(2)O_(4)is mainly attributed to the facile release of oxide and proton ions,and improved synergistic incorporation abilities associated with interplay of multivalent Fe^(3+)/Fe^(2+)and La^(3+)ions.Using LaFe_(2)O_(4)as cathode over proton conducting BaZr_(0.4)Ce_(0.4)Y_(0.2)O_(3)(BZCY)electrolyte,the fuel cell has delivered a high-power density of 806 mW/cm^(2)operating at 500℃.Different spectroscopic and calculations methods such as UV-visible,Raman,X-ray photoelectron spectroscopy and density functional theory(DFT)calculations were performed to screen the potential application of LaFe_(2)O_(4)as cathode.This study would help in developing functional cobalt-free ORR electrocatalysts for low temperature-PCFCs(LT-PCFCs)and solid oxide fuel cells(SOFCs)applications.
文摘Solid oxide fuel cells(SOFCs)and electrolysis cells(SOECs)are promising energy conversion devices,on whose basis green hydrogen energy technologies can be developed to support the transition to a carbon-free future.As compared with oxygen-conducting cells,the operational temperatures of protonic ceramic fuel cells(PCFCs)and electrolysis cells(PCECs)can be reduced by several hundreds of degrees(down to low-and intermediatetemperature ranges of 400–700C)while maintaining high performance and efficiency.This is due to the distinctive characteristics of charge carriers for proton-conducting electrolytes.However,despite achieving outstanding lab-scale performance,the prospects for industrial scaling of PCFCs and PCECs remain hazy,at least in the near future,in contrast to commercially available SOFCs and SOECs.In this review,we reveal the reasons for the delayed technological development,which need to be addressed in order to transfer fundamental findings into industrial processes.Possible solutions to the identified problems are also highlighted.
基金supported by the National Natural Science Foundation of China(No.51802200)the Startup Funding for Talents at University of South China.
文摘Efforts to improve the performance of protonic ceramic fuel cells(PCFCs)have been hampered by the limited availability of cathode materials with high activity and durability.One potential approach to enhance electrocatalytic performance is by modifying the particle morphology of the cathode,which potentially reforms transport properties and active reaction sites.Herein,the configuration of cathode particles via controllable growth of cubes was used to ameliorate perovskite-related Pr_(1.5)Ba_(1.5)Cu_(3)O_(7)(PBC).The PBC particle geometry changes to a cube when the calcination temperature is switched from 900 to 950℃,exposing the{100}crystal facets on the surface.This gives rise to more surface oxygen vacancies and efficient Cu^(2+)-O-Cu^(3+)electron hopping transition paths,favoring high electrocatalytic activity with expeditious oxygen adsorption/activation and facilitating the oxygen reduction reaction(ORR)process.The particle-cubic PBC cathode assembled at 950℃(PBC-950)exhibited significantly enhanced performance,with a power output of 1982 mW·cm^(−2) and a polarization resistance(RP)of 0.028Ω·cm2 at 700℃ on a PCFC,outperforming other Co-based and Cu-based single-phase cathodes reported in the literature.Overall,the superior power and polarization performance,along with excellent durability over 200 h,suggest that PBC-950 is a promising alternative for PCFC cathodes.This study demonstrates the potential of controlling particle growth to design highly active electrodes with specialized properties,opening new avenues for material design in PCFCs and related electrocatalytic fields.
基金support from the National Natural Science Foundation of China(Nos.52072134 and 52272205)the Key Research and Development Program of Hubei Province of China(Nos.2021BCA149 and 2022BAA087)+1 种基金the Natural Science Foundation for Distinguished Young Scholars of Hubei Province of China(No.2021CFA072)the special fund for Science and Technology Innovation Teams of Shanxi Province(No.202304051001007。
文摘Obtaining high-performance cathodes is critical for protonic ceramic fuel cells(PCFCs),as cathode performance significantly impacts fuel cell performance.A full understanding of the interactions among the diverse properties of cathode materials would benefit cathode design.In this study,PrBaFe_(2)O_(6-δ)(PBF)was doped with various dopants,including cobalt(Co),Ni,Cu,Zn,and Mn.Experiments and first-principles calculations are used to study the key properties of dopant-modified PrBaFe_(2)O_(6-δ),including oxygen vacancy(VO)creation,hydration ability,proton mobility,and oxygen reduction reaction(ORR)activity.There is no perfect dopant that can improve every property to its full potential.Instead,different dopants can impact different properties of the material.Co-dopant has the best cathode performance since it balances the material’s instinctive properties,even though it does not provide a significant advantage in the formation of VO.PCFC utilizing Co-doped PrBaFe_(2)O_(6-δ)cathode has a high performance of 1680 mW·cm^(-2) at 700℃,which is greater than that of the other dopant-tailored PrBaFe_(2)O_(6-δ)cathodes reported in this study and is one of the largest ever recorded for PrBaFe_(2)O_(6-δ)-based cathodes for PCFCs.Co-doped PrBaFe_(2)O_(6-δ)cathode is further demonstrated to be robust,with excellent operational stability.This study not only provides a potential cathode candidate for PCFCs but also suggests an intriguing approach to cathode design by carefully examining and balancing different vital properties of the material.
基金supported by the National Natural Science Foundation of China(Grant Nos.22278081,22008034,U2005215,and 22378069)Fujian Science and Technology Major Project(2020HZ07009)+2 种基金the Natural Science Foundation of Fujian Province,China(Grant Nos.2023J01066 and 2022J05027)the Talent Program of Fuzhou University(XRC-22036)Fujian Science and Technology Innovation Key Project(2022G02012).
文摘Ammonia is an exceptional fuel for solid oxide fuel cells(SOFCs),because of the high content of hydrogen and the advantages of carbon neutrality.However,the challenge lies in its unsatisfactory performance at intermediate temperatures(500‒600℃),impeding its advancement.An electrolyte-supported proton-ceramic fuel cell(PCFC)was fabricated employing BaZr_(0.1)Ce_(0.7)Y_(0.2)O_(3)–δ(BZCY)as the electrolyte and Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3)–δ(BSCF)as the cathode.In this study,the performance of PCFC using NH_(3)as fuel within an operating temperature range of 500‒700℃ was improved by adding an M(Ni,Ru)/CeO_(2)catalyst layer to reconstruct the anode surface.The electrochemical performance of direct ammonia PCFC(DA-PCFC)were improved to different extents.Compared to H_(2)as fuel,the degradation ratio of peak power densities(PPDs)of Ni/CeO_(2)-loaded PCFC fueled with NH_(3)decreased at 700‒500℃,with a decrease to 13.3%at 700℃ and 30.7%at 500℃.The findings indicate that Ru-based catalysts have a greater promise for direct ammonia SOFCs(DA-SOFCs)at operating temperatures below 600℃.However,the enhancement effect becomes less significant above 600℃ when compared to Ni-based catalysts.
基金supported by the Basic Science Center Program for Ordered Energy Conversion[No.51888103]the key project[No.52336009]of NSFC+2 种基金the Fundamental Research Funds for the Central Universities and the National Key Research and Development Program of China[No.2021-YFB4001405]the Southeast University Basic Research Program,the General Program of NSFCthe Jiangsu Provincial Basic Research Program.
文摘Current perovskite oxide electrolytes,i.e.,acceptor-doped Ba(Ce,Zr)O_(3-δ),exhibit proton conductivity ranging from 10^(-3) to 10^(-2) S cm^(−1) at 600℃ for protonic ceramic fuel cells(PCFCs),which rely on the structural defects.However,bulk doping and sintering restrict these oxides to possess higher ionic conductivity.New-generation PCFCs with alternative ion conduction mechanism need to be developed.This study presents a novel approach to realize high proton conduction along a fluorite oxide-ion conductor gadolinium-doped ceria(GDC:Gd_(0.1)Ce_(0.9)O_(2-δ))by electrochemical proton injection via a fuel cell process.A high protonic conductivity of 0.158 S cm^(−1) has been achieved.This fuel cell employing a 400-μm-thick GDC electrolyte delivered a peak power output close to 1,000 mW cm^(−2) at 500℃.Proton conduction is verified by electrochemical impedance spectroscopy,proton filtering cell and isotopic effect,and so on.Proton injection into GDC after fuel cell testing is clarified by x-ray photoelectron spectroscopy,Raman spectra,^(1)H solid-state nuclear magnetic resonance spectra,and so on.Furthermore,a synergistic mechanism involving both surface proton conduction and bulk oxygen-ion migration is proposed by comparing electrochemical impedance spectroscopy with distribution of relaxation time results of GDC and pure ceria.This finding may provide new insights into the ion transport mechanism on fluorite oxides and open new avenues for advanced low-temperature PCFCs.
基金the support by the National Key R&D Program of China(2018YFE0124700)the National Natural Science Foundation of China(52102279,52072134,and 51972128)+1 种基金Natural Science Foundation of Shandong Province(ZR2021QE283)Department of Science and Technology of Hubei Province(2021CBA149 and 2021CFA072).
文摘Slow oxygen reduction reaction(ORR)involving proton transport remains the limiting factor for electrochemical performance of proton-conducting cathodes.To further reduce the operating temperature of protonic ceramic fuel cells(PCFCs),developing triple-conducting cathodes with excellent electrochemical performance is required.In this study,K-doped BaCo_(0.4)Fe_(0.4)Zr_(0.2)O_(3−δ)(BCFZ442)series were developed and used as the cathodes of the PCFCs,and their crystal structure,conductivity,hydration capability,and electrochemical performance were characterized in detail.Among them,Ba_(0.9)K_(0.1)Co_(0.4)Fe_(0.4)Zr_(0.2)O_(3−δ)(K10)cathode has the best electrochemical performance,which can be attributed to its high electron(e^(−))/oxygen ion(O^(2−))/H^(+)conductivity and proton uptake capacity.At 750℃,the polarization resistance of the K10 cathode is only 0.009Ω·cm^(2),the peak power density(PPD)of the single cell with the K10 cathode is close to 1 W·cm^(−2),and there is no significant degradation within 150 h.Excellent electrochemical performance and durability make K10 a promising cathode material for the PCFCs.This work can provide a guidance for further improving the proton transport capability of the triple-conducting oxides,which is of great significance for developing the PCFC cathodes with excellent electrochemical performance.
基金financially supported by the Fundamental Research Funds for the Central Universities(No.2019GF10).
文摘New two-layer Ruddlesden-Popper(RP)oxide La_(0.25)Sr_(2.75)FeNiO_(7-δ)(LSFN)in the combination of Sr_(3)Fe_(2)O_(7-δ) and La_(3)Ni_(2)O_(7-δ) was successfully synthesized and studied as the potential active single-phase and composite cathode for protonic ceramics fuel cells(PCFCs).LSFN with the tetragonal symmetrical structure(IMmmm)is confinned,and the co-existence of Fe^(3+)/Fe^(4+) and Ni^(3+)/Ni^(2+) couples is demonstrated by X-ray photoelectron spectrometer(XPS)analysis.The LSFN conductivity is apparently enhanced after Ni doping in Fe-site,and nearly three times those of Sr_(3)Fe_(2)O_(7-δ),which is directly related to the carrier concentration and conductor mechanism.Importantly,anode supported PCFCs using LSFN-BaZr_(0.1)Ce_(0.7)Y_(0.2)O_(3-δ)(LSFN-BZCY)composite cathode achieved high power density(426 mW·cm^(-2) at 650℃)and low electrode interface polarization resistance(0.26Ω·cm^(2)).Besides,distribution of relaxation time(DRT)function technology was further used to analyse the electrode polarization processes.The observed three peaks(Pl,P2,and P3)separated by DRT shifted to the high frequency region with the decreasing temperature,suggesting that the charge transfer at the electrode-electrolyte interfaces becomes more difficult at reduced temperatures.Preliminary results demonstrate that new two-layer RP phase LSFN can be a promising cathode candidate for PCFCs.
文摘Protonic ceramic fuel cells(PCFCs)offer a convenient means for electrochemical conversion of chemical energy into electricity at intermediate temperatures with very high efficiency.Although BaCeO_(3)-and BaZrO_(3)-based complex oxides have been positioned as the most promising PCFC electrolytes,the design of new protonic conductors with improved properties is of paramount importance.Within the present work,we studied transport properties of scandium-doped barium stannate(Sc-doped BaSnO_(3)).Our analysis included the fabrication of porous and dense BaSn_(1−x)Sc_(x)O_(3−δ)ceramic materials(0≤x≤0.37),as well as a comprehensive analysis of their total,ionic,and electronic conductivities across all the experimental conditions realized under the PCFC operation:both air and hydrogen atmospheres with various water vapor partial pressures(p(H2O)),and a temperature range of 500–900℃.This work reports on electrolyte domain boundaries of the undoped and doped BaSnO_(3)for the first time,revealing that pure BaSnO_(3)exhibits mixed ionic–electronic conduction behavior under both oxidizing and reducing conditions,while the Sc-doping results in the gradual improvement of ionic(including protonic)conductivity,extending the electrolyte domain boundaries towards reduced atmospheres.This latter property makes the heavilydoped BaSnO_(3)representatives attractive for PCFC applications.
