Preparation And Research Of Low-temperature Solid Oxide Fuel Cell In BaCeO₃ Matrix Sub-conductor

Energy is the basis of the social development.All countries in the world still use fossil fuels as the main energy resource.China uses fossil fuel in a higher proportion.Therefore,it is urgent to exploit the new energy.Fuel Cell as a new type of efficient and environment friendly power generation device has attracted people attentions.Among several existing fuel cells,solid oxide fuel cell?SOFC?is a new energy technology which can realize high efficiency power generation on the basis of existing energy supply system.However,the traditional SOFC has high operating temperature,which may lead to electrode sintering,difficult sealing,interface diffusion and other problems.Therefore,reducing the operating temperature of SOFC is the main direction of research and development.The proton conducting solid oxide fuel cells provides an important research direction for reducing the operating temperature of the cells.In this paper,sintering activity and electrochemical performance of BaCeO₃-based proton conducting SOFCs were studied,and the performance of traditional BaCeO₃-based cells were greatly improved.The main results are as follows:?1?When NiO was used as sintering additive in BaZr_0.1Ce_0.7Y_0.2O_3-??BZCY?electrolyte,the performance of the fuel cell was obviously improved.The experimental results show that the conductivity of electrolyte and the performance of cells can be improved by adding sintering additive NiO.Moreover,the performance of internally doping is better than that of externally doping,With BaZr_0.1Ce_0.66Ni_0.04Y_0.2O_3-??BZCNY?as the electrolyte,a proton conducting solid oxide fuel cell shows a large peak power density of 477 mW cm^-2 at 600°C with a high electrolyte membrane conductivity of 6.3×10^-3 S cm^-1.?2?It is found that microwave sintering can effectively reduce the sintering temperature.Different from the conventional thermal treatment priciple,the microwave sintering can make the samples more uniformly heated,BaZr_0.1Ce_0.7Y_0.2O_3-??BZCY?powders were successfully prepared by microwave sintering.enabling the formation of pure phase BaZr_0.1Ce_0.7Y_0.2O_3-?powder at a relatively low temperature with a short dwell time of 1 h,while the same pure phase can only be formed at 1000 ^oC in an electric furnace.Importantly,the grain size for the microwave prepared BaZr_0.1Ce_0.7Y_0.2O_3-?powder is much smaller than that of the conventionally thermal treated BaZr_0.1Ce_0.7Y_0.2O_3-?powder.It is reported that the smaller the grain size of electrolyte powders,the better the formation of high quality and density electrolyte films during the electrolyte sintering procedure.A fuel cell fabricated using this electrolyte membrane with a conductivity of 7×10^-3 S cm^-11 delivers a power output of 791 mW cm^-2 at 700 ^oC.The advantages of microwave sintering method also provide the conditions for one step co-sintered preparation of SOFC.Cells are prepared by one-step co-sintered method using microwave sintering,The microwave sintering method can not only enhance the electrolyte densification but also improve the cathode/electrolyte interface,which were critical for improving fuel cell performance.?3?Optimizing cathode performance is also an important direction to improve SOFC performance.The SrCo_0.9Nb_0.1O_3-??SCNO?cathode prepared by solid-state reaction,which has many shortcomings and limit its application.In this experiment,SCNO was successfully synthesized by liquid-phase method.Compared with solid-phase reaction method,liquid-phase method has lower temperature and gets smaller cathode grains?small grains are more conducive used in cathode materials?.It is more important to improve the performance of the SOFC.In addition,Sr²⁺,Co³⁺and Nb⁵⁺can be co-soluble in aqueous solution by liquid phase method,which provides conditions for improving cells performance by ion impregnation method.At the same time,it provides a direction for the preparation of Nb-containing compounds in SOFC,and also has a significance for reducing the working temperature of SOFC.