Study On Preparation And Performance Of Cathode Materials For Medium And Low Temperature Proton Conducted Solid Oxide Fuel Cell

In order to solve the energy problem and realize the sustainable development needs of the earth,efficient and clean solid oxide fuel cells（SOFC）have received extensive attention.Reducing the operating temperature is currently the main development requirement.To ensure the overall operating efficiency of the battery,the choice of cathode material is crucial.The thesis research focuses on the development of high-performance materials suitable for H-SOFC,through doping to improve the electrochemical and catalytic performance of cathode materials and obtain ideal cell performance under low and medium temperature conditions.In this paper,La₂NiO_4+δis used as the parent material to optimize the system.The A site is doped with alkaline earth metal elements（Ca,Sr,Ba）,respectively.Ba)Comparative analysis of materials from the perspectives of structure,conductivity and performance.In the middle temperature region（600-700°C）,calcium-doped La₂NiO_4+δmaterial is the best choice among the three alkaline earth elements.In the low temperature region（550-600°C）,Sr-doped single cells have better performance.The results show that La_1.5A_0.5NiO_4+δ（A=Ca and Sr）is a promising cathode material for H-SOFC.For the system with the best performance(La₂NiO_4+δdoped with Ca),the composition of the system was optimized,and the possibility of using La_2-xCa_xNiO_4+δmaterial as H-SOFC cathode was evaluated by using different Ca doping amounts（x=0,0.25,0.5,0.75）.Doping Ca in La₂NiO_4+δcan effectively improve the conductivity and the oxygen reduction reaction（ORR）on the surface,which has good chemical stability and Tec compatibility with electrolyte.The results show that La_1.5Ca_0.5NiO_4+δcathode exhibits the best electrochemical performance in single cell test.The maximum power density（MPD）and polarization resistance（RP）of La_1.5Ca_0.5NiO_4+δat700℃are 923 mW·cm^-2and 0.053Ω·cm^-2respectively.This work indicates that the single-phase RP layered material La_1.5Ca_0.5NiO_4+δmay be a promising cathode for H-SOFC.By combining the above-mentioned mixed ion electronic conductor material(La_1.5Ca_0.5NiO_4+δ)with the best performance and 30wt%proton conductor material（BZCY）,an LCNO-BZCY capable of conducting three phases(H⁺,e^-,O^2-)can be obtained cathode.The aim is to increase the three-phase interface length of the material and expand the electrochemical reaction area of the oxygen reduction reaction（ORR）.This composite material significantly improves the thermal expansion properties of the material and reduces the thermal and mechanical incompatibility between the cathode and the electrolyte.The composite cathode LCNO-BZCY has good electrical properties and is an excellent cathode material worthy of continued development.