A Study Of Modifying（La,Sr）（Co,Fe）O₃ Surface By Plasma Glow Discharge

Solid oxide fuel cells(SOFCs) is an clean and efficient device that could transfer chemical energy to power. Recent years intermediate temperature solid oxide fuel cells(IT-SOFCs) attracts researcher as lower temperature brings lower cost and higher durability. It is a significant problem to improve the rate of reaction on the surface of cathode. In this paper a plasma glow discharge method is used for the first time to improve the oxygen reduction reaction(ORR) of cathode. The electric conductivity relaxtion method(ECR) and distribution of relaxtion time(DRT) is applied to characterize the reaction rate of ORR. A better method is proposed to calculate DRT from electrochemical impedance spectrum(EIS).In the paper we adopt plasma glow discharge method to modify the surface of LSCF and coat nano-scale particles on the surface. The oxygen reduction reaction of the surface is promoted. The hollow cathode of Ni/Cu/Fe is used as target. The atmosphere of H2/Ar is plasma and through bombarding metal atoms is coated on the surface. Samples are placed in the hollow cathode and as a result the metallic atoms deposit on the surface.Because of the catalytic performance of transition metal, Ni/Cu/Fe are chosen as target. The relation between the treatment factors(time and temperature) and morphology of film is discussed. As time goes, the size of particles increases and the amount of particles increases. As temperature increase, the size of particles trends to increase. In lower temperature, lower valent metal oxide is preferred. The morphology of coating nickel and iron is column and while coating copper, the morphology is sphere and polygonal. Through changing the factors, the morphology of coating Ni/Cu/Fe could be controlled. The former works provides methods for modifying LSCF on the cell.The optimized treatment of coating nickel is characterized by electrical conductivity relaxtion methods and the surface exchange coefficient is proved to be improved by a magnitude. The formula which represents the control of bulk transport in LSCF is given. Later the mechanism of distribution of relaxtion time is optimized, which has a higher resolution and provide powerful ways to characterize the surface process. Considering the resolution and robustness of the method, the optimized factors is obtained. The Gauss method is used to calculate the EIS data of LSCF in different temperature and the process limiting the performance of LSCF is shown.