| Solid oxide fuel cells(SOFCs)are power generation devices that convert the chemical energy of fuels directly into electrical energy.It has the characteristics of high efficiency,low pollution,fuel flexibility and so on.Cost is main reason in the large-scale commercial application of SOFCs.The symmetrical SOFCs can significantly reduce the manufacture cost of the battery and also solve the problems of carbon deposition and sulfur poisoning for the traditional Ni-based anodes.Moreover,the symmetrical SOFC can flexibly switch to the solid oxide electrolytic cell(SOECs)mode to electrolysis H2O and CO2 to produce H2 or syngas.We obtained several high-performance symmetrical electrode materials by modifying the existing SOFCs cathode materials,including the following three aspects:1.The single-phase La0.6Sr0.4Co0.2Fe0.7Mo0.1O3-? symmetrical electrode is obtained by doping Mo at the Fe site of the commercial La0.6SrO0.4Co0.2Fe0.8O3-? cathode.La0.6Sr0.4Co0.2Fe0.7Mo0.1O3-? shows good structural stability in reducing and oxidizing conditions.At 800?,the polarization resistances are 0.041 and 0.266 ?cm2 in air and H2,respectively.The electrochemical impedance stability measurement results show that La0.6Sr0.4Co0.2Fe0.7Mo0.1 O3-? demonstrates satisfying electrochemical stability either as cathode or anode.The output performances of the La0.6Sr0.4Co0.2Fe0.7Mo0.1O3-? symmetrical electrode are 929 and 481 mW cm-2 under H2 and ethanol fuel at 850?,respectively.The output performance stability test of a single cell is carried out in liquid petroleum gas and the La0.6Sr0.4Co0.2Fe0.7Mo0.1O3-?electrode shows good ability of tolerating carbon deposition and resisting sulfur poisoning.2.In this work,we report a new family of double perovskite symmetrical electrodes Sr2Ti1-xCoxFeO6-?(x=0,0.1,0.2,0.3,STCF)for SSOFCs.The Sr2Ti0.8Co0.2FeO6-?(STC02F)electrode can be exsoluted with the cobalt-iron alloy nanoparticles and can maintain the double perovskite structure in reducing atmosphere.The STC02F electrode also has good physical and chemical compatibility with LSGM electrolyte.The polarization resistance(Rp)values of the STC02F-based symmetrical cells are 0.026 and 0303 ?cm2 at 800? in air and in hydrogen,respectively.The output power densities of the single cell with the configuration STC02F/LSGM/STC02F reach 555,180,404,and 390 mW cm-2 at 800? using H2,liquefied petroleum gas,C2H5OH,and CH3OH,respectively.Moreover,the symmetrical cell with STC02F electrode shows good electrochemical performance and stability for the electrolysis of H2O or CO2 and co-electrolysis of H2O/CO2 for SOECs.3.In this work,the layered perovskites PrBaFe2-xCoxO5+?(x=0,0.2)are studied as symmetrical electrodes for SOFCs and SOECs.PrBaFe1.8Co0.2O5+?(PBFC02)has better catalytic performance for oxygen reduction reaction(ORR)and hydrogen oxidation reaction(HOR)than PrBaFe2O5+?(PBF).In H2,PBFC02 sample would decompose to PBF,Ba6Pr2Fe4O15 and Co3Fe7.After calcining the decomposed products at high temperature in air,the sample can return to the original perovskite structure PBFC02 sample,indicating a good redox reversibility.The X-ray diffractometer(XRD)and Energy dispersive spectrometer(EDS)results demonstrate that PBFC02 sample has good chemical compatibility with LSGM electrolyte.At 800?,the polarization resistance values of PBFC02 symmetrical electrodes are 0.026 and 0.321 ?cm2 in air and H2,respectively.The output performances of the electrolyte-supported single cell with the PBFC02 symmetrical electrodes are 734,625 and 268 mW cm-2 at 850? under H2,liquefied petroleum gas,and C2H5OH fuel,respectively.Moreover,the symmetrical cell with the PBFC02 electrodes shows good electrochemical performance and stability for the co-electrolysis of H2O/CO2 at intermediate temperatures for SOECs. |
PDF Full Text Request