Design Of A Proton Conductor Solid Oxide Fuel Cell Cathode And Application Of Microwave Sintering

The progress in solid state electrochemical devices operating at high temperature,such as solid oxide fuel cell（SOFC）,needs to be continuously developed and found new electrode materials and solid electrolyte materials with excellent performance,optimize their preparation methods and processing technology,and strive to understand the mechanism of electrochemistry reaction deeply.By reducing the working temperature to the so-called intermediate temperature（IT range 500℃-800℃）,the problem of relatively high cost and degradation of SOFC can be partially solved,which makes it possible to use cheaper components to reduce the chemical interaction and thermal mechanical incompatibility of materials in fuel cells.On the other hand,the lower operating temperature will also lead to the larger problem of electrode polarization,which may be the key to the overall performance.Proton conductor solid oxide fuel cell（H-SOFC）has a great advantage in low temperature environment because of its lower activation energy than O-SOFC,which makes H-SOFC develop further.It is an important part to understand the cathode mechanism of H-SOFC,and its mechanism is more complex than O-SOFC.As we all know,the cathode/electrolyte interface plays an important role in the performance of SOFC.The interface modification not only improves the contact performance of SOFC,but also expands the reactive center.Therefore,in this study,we have done the following:（1）The performance of the battery was improved by the preparation of Ba_0.5Sr_0.5Co_0.7Mo_0.1Fe_0.2O_3-δ（BSCMF）cathode material by doping Mo at B-position.The experimental results show that the cathode material is feasible.The radius of Mo⁶⁺doped in BSCF is similar to that of Fe⁴⁺,Co³⁺ions,but the charge is large.The cubic structure of BSCF was stabilized at medium temperature,and the electrochemical performance of BSCF as cathode material of H-SOFC was improved.At the same time,the first principle of calculation and simulation results show that the formation energy of oxygen vacancy in BSCMF is lower and the proton transfer barrier is reduced,which is similar to the actual experimental results.In the same test environment,the power of the BSCF single-phase cathode cell is 0.19 W cm^-2 at 700℃,while that of the BSCMF single-phase cathode cell is 0.63 W cm^-2.（2）The cathode layer of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ（BSCF）proton conductor solid oxide fuel cell was prepared by microwave sintering method.The traditional sintering process is carried out at 1000℃for several hours.Unlike the traditional sintering process,the cathode layer of BSCF can adhere well to the electrolyte layer after sintering at 900℃for 10minutes.This method can help the cathode layer to maintain the microstructure which is conducive to the cathode reaction,and reduce the potential diffusion of elements between the cathode layer and Ba Ce_0.7Zr_0.1Y_0.2O_3-δ（BCZY）electrolyte,so as to improve the compatibility of various parts of the battery.The power output of the battery with microwave sintering BSCF cathode layer is 0.96 W cm^-2 at 700℃,while that of the battery with conventional sintering cathode layer is 0.33 W cm^-2.In order to find the best temperature and time of microwave sintering,the microwave sintering at different temperature and time was compared.