Preparation,Structure Evolution And Application Research Of Co/Ti Co-Doped Strontium Lanthanum Ferrite Perovskite Anode

Solid oxide fuel cell(SOFC)has high power generation efficiency and can directly use hydrocarbon fuels.It has potential applications in large-scale centralized power supply,distributed power generation,household combined heat and power and even transportation.Among them,one of the most critical tasks is to prepare electrode materials that can work efficiently in various fuels and are cost-competitive.Compared with Ni-YSZ,oxide ceramic anode has low conductivity,large polarization resistance,and poor cell performance.The introduction of nano metal particles on the surface by in-situ precipitation can significantly improve the electrochemical catalytic activity while inhibiting the occurrence of carbon deposition reactions.In this paper,based on the SrFeO₃ perovskite oxide,the layered perovskite(La_0.4Sr_0.6)₂Fe O₄ system and single perovskite La_0.4Sr_0.6Fe O₃ system were designed and prepared by the method of doping Co/Ti at the B site and introducing the A deficiency The process and mechanism of the in-situ precipitation of nano-metal particles,the structure and electrochemical performance evolution under multi-physical fields(temperature field,atmosphere field)are studied,and the controllable preparation and stable operation of nano heterogeneous anodes are realized.The A₂BO₄ type layered perovskite structure(La_0.8Sr_1.2)_1-xTi_0.2Fe_0.8-yCo_yO₄(x=0,0.05,0.1;y=0,0.05,0.1,0.15,0.2)was successfully prepared.The A-deficiency(La_0.8Sr_1.2)_0.95Ti_0.2Fe_0.7Co_0.1O₄(K95)anode remained A₂BO₄ structure stable after being reduced at 850?and 3%H₂O-H₂ for 20h,and at the same time,?50nm metal nanoparticles were precipitated in situ.The introduction of A deficiency significantly increased the conductivity,the conductivity in 850?air reached 687.51 S/cm,2.5 times that of(La_0.8Sr_1.2)Ti_0.2Fe_0.7Co_0.1O₄(K10).At the same time,the ohmic resistance and polarization resistance were reduced,and the maximum power density and current density were increased.La_0.4Sr_0.6Fe_0.7Ti_0.3-xCo_xO_3-?(LSFTC,x=0,0.05,0.1,0.2)single perovskite oxide was prepared and used as SOFC symmetric electrode.The results show that Co doping effectively improves the conductivity of the electrode and the cathode oxygen reduction activity,and reduces the cathode polarization resistance and its dependence on the change of oxygen partial pressure.When p O₂=0.21atm,the maximum conductivity of La_0.4Sr_0.6Fe_0.7Ti_0.25Co_0.05O_3-?is₍600?,(3)=81/(88),and the minimum polarization resistance is 0.1?cm² at 750?.When LSFTC is used as an anode,a nano-metal particle-perovskite oxide heterostructure anode is generated in situ.As the amount of Co doping increases,the amount of nanoparticles precipitated is larger,which improves the adsorption process of free hydrogen on the anode surface;however,the single perovskite structure after metal precipitation is gradually shifting to the layered perovskite structure with rich AO phase.The evolution has an adverse effect on anode conductivity and catalytic activity under lower H₂ partial pressure.At p H₂=0.97atm,the maximum power density of the LSFTC-5 anode reaches 0.45W/cm².Finally,the electrochemical performance of La_0.4Sr_0.6Fe_0.7Ti_0.1Co_0.2O₃ anode cell under hydrocarbon fuel(H₂-CO,H₂-CH₄,CO₂-CH₄)was explored.Under the H₂-CO syngas fuel,it is found that different CO content has little effect on the ohmic resistance of the single cell,and it shows a higher output power density under high CO content.In 80%CH₄-20%H₂ hydrogen-doped natural gas,the maximum power density reached 0.55 W/cm²,and it operated stably for?140h without significant attenuation.