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
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
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
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
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.
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.
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.
