Study On Electrode Materials For Symmetrical Solid Oxide Cells

As an energy conversion device,a solid oxide cell（SOC）can directly convert the chemical energy of the fuel into electrical energy,or convert the electrical energy into the chemical energy of the fuel by electrolytic reduction of water and carbon dioxide into hydrogen and carbon monoxide.It is not limited by the Carnot cycle and has the advantages of high energy conversion efficiency,cleanliness and no pollution.The further practical application of solid oxide battery devices is currently limited by the catalytic activity and stability of their electrode materials.The work of this thesis mainly takes the electrode materials of symmetric solid oxide batteries（SSOC）as the research object,and uses the B site doping and in-situ exsolution technology to carry out the modification research of the electrode materials.The thesis mainly selects and studies the following electrode materials:SrFeO_3-δ（SFO）;SrFe_0.9Mo_0.1O_3-δ（SFM）which obtained by doping Mo at B site of SFO;in situ exsolution modification of SrFe_0.95Mo_0.1O_3-δ（SF95M）obtained by fine-tuning the stoichiometric ratio of SFM;in situ exsolution modification of SrFe_1.05O_3-δ（SF105O）obtained by fine-tuning the stoichiometric ratio of SFO.The research on SSOC based on the above four electrode materials found:doping Mo at the B site can effectively improve the catalytic performance of SFO electrode materials,and the maximum power density of SFM-based SSOC at 800 ℃ is increased by about 8%compared with SFO-based SSOC;the in-situ exsolution surface modification technology can effectively improve the catalytic performance of SFM electrode materials.Compared with the SFM-based SSOC,the maximum power density of the SF95M-based SSOC at 800 ℃ is increased by about 7.9%.According to the analysis,it is mainly because the Fe nanoparticles are exsolved on the surface,which enhances the catalytic activity of the electrode material for the fuel gas,and the uniformly distributed nanoparticles also improve the electrode ability to capture the fuel gas and reduce the polarization impedance of the cell;compared with the SSOC based on SF95M electrode at 800 o C,the SSOC based on SF105O electrode has a maximum power density increased by about 132%under pure hydrogen atmosphere.It is analyzed that the structure of SF105O without B site doping will be transformed into a non-traditional perovskite structure after in-situ desolubilization.The synergistic effect of Fe nanoparticles exsolution on the surface and the substrate enhanced the catalytic activity of the electrode for fuel gas.Through comparative analysis,the thesis believes that both B-site doping and in-situ exsolution surface modification can effectively improve the electrode catalytic performance of SFO,and the SSOC based on in-situ exsolution of SF105O electrode achieves the highest power density(at 800℃,1.3W.cm^-2)and 1200 hours of stable output;further electrolysis of water,carbon dioxide,and co-electrolysis of water and carbon dioxide showed that the SSOC had electrolytic current densities of 1.778,0.943,and1.265 A.cm^-2 at 800 ℃ and 1.6 V,respectively.Therefore,SF105O-based SSOC has a high practical promotion value as an energy conversion device,and the synergistic effect of non-traditional perovskite substrate structure and in-situ exsolution modification on the catalytic performance of the electrode needs to be further studied.