Preparation And Properties Of Perovskite-like Anode Materials

As human beings enter the 21st century,the demand for energy is increasing day by day,traditional energy is increasingly exhausted,and the aggravation of greenhouse effect caused by fossil fuel combustion makes human beings pay more attention to the development and research of new green energy.Solid oxide fuel cells(SOFCs)have attracted extensive attention due to their high efficiency and low pollution.As a key component of fuel cell,the electrocatalytic activity of anode directly determines the performance of fuel cell.The traditional Ni/YSZ anode materials can cause carbon deposition and sulfur poisoning in hydrocarbon and sulphide-containing fuels,which hinder the fuel passing through and deactivate the anode,thus affecting the performance of the battery.Therefore,it is very important to develop a new type of carbon deposition resistant anode materials.In this paper,the Ruddlesden-Popper(RP)type anode material Sr₃Fe₂O_7-?with a perovskite-like structure was prepared by the solid-phase method.The research results show that after 10 hours of sintering at 1300? in air,the sample has obtained a single tetragonal phase structure;the maximum conductivity of Sr₃Fe₂O_7-?at 300-850? in air is65.5 S cm^-1,and the conductivity in hydrogen is below It is 0.89 S cm^-1 at 850?.XRD analysis of the sample after hydrogen reduction shows that Sr₃Fe₂O_7-?is partially decomposed into Sr O and Sr₂Fe₂O₅ after hydrogen reduction;La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-?is used as the electrolyte,Ce_0.8Sm_0.2O_1.9 is a single cell with a buffer layer,the peak power density at 850? in hydrogen is 698 m W cm^-2,and the peak power density at 900? in methane is 80 m W cm^-2,short-term stability test results It shows that Sr₃Fe₂O_7-?anode material shows good carbon deposition resistance.In order to improve the electrical properties and structural stability of the Sr₃Fe₂O_7-?anode material,we prepared B-site Mo-doped Sr₃Fe_2-xMo_xO_7-?(x=0.1,0.2,0.3)sample.As the amount of Mo doping increases,the conductivity of the sample in hydrogen shows an upward trend.The conductivity of the Sr₃Fe_1.7Mo_0.3O_7-?sample reaches 3.82 S cm^-1 at850?;at the same time,the doping causes the thermal expansion coefficient of the sample The decrease of the undeployment rate is 20.23×10^-6 K^-1 when it is not doped to 18.16×10^-6K^-1;Sr₃Fe_1.7Mo_0.3O_7-?is a single cell with anode material,and when hydrogen is used as a fuel,the temperature of The peak power density is 599 m W cm^-2,and the peak power density at 900? when methane is used as the fuel is 68 m W cm^-2.After 24 hours of stability testing,the battery performance has not significantly decreased.At the same time,B Nb-doped Sr₃Fe_2-xNb_xO_7-?(x=0.05,0.10,0.15,0.20,0.25)samples were prepared to change the structural and thermal properties of Sr₃Fe₂O_7-?materials.The addition of Nb significantly reduced the thermal expansion coefficient of the samples,and the coefficient of thermal expansion of the samples after doping ranged from 19.24×10^-6K^-1 to 17.36×10^-6 K^-1,which is better matched with the common electrolyte materials.The conductivity of Sr₃Fe_1.95Nb_0.05O_7-?at 850? of hydrogen is 0.82 S cm^-1,which is slightly lower than that of the undoped sample.At 850?,the single cell has the best performance,with peak power densities of 797 m W cm^-2 and 97 m W cm^-2 in hydrogen and methane,respectively.Compared with the undoped Sr₃Fe₂O_7-?cell,the performance is improved,and the long-term stability is good in hydrogen and methane.In summary,the perovskite-like Sr₃Fe₂O_7-?based material shows good electrical,thermal and electrochemical properties,and is expected to be a new type of solid oxide fuel cell anode material resistant to carbon deposition.