Numerical Simulation Study Of Cathode Contact Resistance In Planar Solid Oxide Fuel Cell

Solid oxide fuel cell(SOFC)has broad application fields because of its many advantages such as efficiency,quietness,fuel flexibility and so on.A large number of studies have found that the performance of the stack is poorer than that of a single cell.One of the main reasons is the large contact resistance between the cathode and the interconnector.However,the microscopic morphology of the contact surface constructed by the theoretical contact resistance model and the statistical contact resistance model is very different from the actual microstructure of the contact surface,which limits its applicability.In this paper,based on the micro-morphology of the contact surface,a numerical model of cathode contact resistance is established to explore the influence of different factors on the cathode contact resistance.On this basis,a flat SOFC electrochemical model with cathode contact resistance is built to deeply study the cathode contact resistance and cell performance dependencies.The specific research contents of this paper are as follows:1.In this paper,the rough surface of the cathode contact layer and the interconnector is constructed based on the WM fractal function.The structure of the cathode contact layer and the interconnector with the rough surface is imported into the cathode contact resistance mechanical model and electrical model to establish the SOFC cathode contact resistance model.Grid verification and simulation result verification are carried out,which lays a foundation for studying the influence of multivariate on the cathode contact resistance.2.Based on the cathode contact resistance mechanics model,the contact stress distribution of the contact interface between the cathode contact layer and the interconnector can be obtained.Based on the electrical model of the cathode contact resistance,the current density distribution at the contact interface can be obtained.According to the distribution of contact stress and current density at the contact interface,it is possible to more intuitively explain the causes and changing trends of cathode contact resistance.3.The effects of Young's modulus,electrical conductivity and external pressure load of the cathode contact layer on the cathode contact resistance are investigated in detail.The results show that the larger the Young's modulus,the larger the cathode contact resistance.When the Young's modulus is larger than 110 GPa,the cathode contact resistance remains basically unchanged.The larger the conductivity,the smaller the cathode contact resistance,when the conductivity is larger than 3400 S/cm,the cathode contact resistance is basically stable.The larger the pressure load,the smaller the cathode contact resistance,and the magnitude of decrease in the cathode contact resistance decreases as the pressure load increases.4.In this paper,a flat SOFC electrochemical model with cathode contact resistance is established to explore the influence of Young's modulus,electrical conductivity and external pressure load on cell power density.It is found that the larger the Young's modulus,the smaller the cell power density.When the Young's modulus is larger than 110 GPa,the power density remains basically unchanged;the larger the conductivity,the larger the cell power density when the conductivity is larger than 3400 S/cm,the power density is basically stable;the larger the pressure load,the larger the cell power density,and the increase in power density decreases with increasing pressure load.5.The dependence of contact area,cathode contact resistance and cell power density on contact materials are studied when LSM,LSCF and Ag are used as cathode contact layer materials under different loads.The results show that although the contact area is the largest when the contact material is LSM,the contact resistance is the largest due to its small conductivity.The power density of the cell with LSM as the cathode contact layer material is most affected by the pressure load.The cell power density with Ag as the cathode contact layer material is affected by the pressure load.