LaNbO₄-based Electrolyte And PrBaCo₂O_5+?-based Cathode Material For Proton Conductor Solid Oxide Fuel Cells

Fuel cell is a new type of electrochemical cell.Its efficient and pollution-free power generation method has great development potential and is considered as the future development trend of energy.Among them,solid oxide fuel cell(SOFC)with its own advantages of solid state structure and not using precious metals as catalysts has received worldwide attention.At present,the biggest obstacle to the development of SOFC is that the operating temperature is too high,which will lead to a series of problems,such as slow start-up,material aging,interface diffusion,performance degradation and so on.Comparing with oxygen ion conducting electrolyte,proton conducting oxide electrolyte can reduce the working temperature,but the power of the battery at low and medium temperature should also be considered.As the core part of fuel cell,electrolyte has the greatest effect the performance of fuel cell.The choice of cathode materials is extensive,which also has a great impact on the performance of the battery.Therefore,the main research direction is to develop and improve electrolyte and cathode materials suitable for low and medium temperature range,improve the electrochemical performance of fuel cells,and promote the commercial development of fuel cells.This paper mainly contains the doping of electrolyte and cathode materials to improve their conductivity and output power.The main work is as follows:(1)NiO was used as dopant in La_0.99Ca_0.01NbO₄(LCNO)electrolyte to improve the battery performance.The results show that adding NiO as dopant can improve the conductivity of the electrolyte.The doping method and doping concentration are also explored.It is found that the performance improvement of internal doping method is better than that of external doping NiO,and the doping concentration should not be too high.The doping concentration of 1%and 2%can make the doping effect the best,and the conductivity can reach more than 1×10^-3S cm-1 at 700?.So the material possesses high application potential with excellent chemical stability.(2)The performance of the battery was improved by optimizing the cathode materials.In this experiment,a new cathode material Pr_0.5Nd_0.5Ba_0.5Sr_0.5Co_1.6Fe_0.4O_5+?(PNBSCF)was prepared by gel-sol method.The doped powder is pure phase after firing at 1000?for 3h.The peak power density of the battery prepared with PNBSCF cathode at 700?is 845 m W cm^-2,which is better than the battery prepared with Pr Ba Co₂O_5+?cathode.This proves that the doping of Nd,Sr and Fe elements can improve the material performance.