Diffusion-reaction model and electrolysis dynamic characteristics of electrode surface and channel in solid oxide electrolytic cell

Abstract

It is of great significance to study the diffusion reaction and dynamic operation characteristics of solid oxide electrolytic cell (SOEC) by establishing physical model. Based on one dimensional mass transfer model in porous media and one-dimensional flow model, the dynamic SOEC diffusion-reaction model is established. According to the experimental results and parameters, numerical method is used to calculate the current density and water vapor concentration distribution. The influence of operating conditions, such as water vapor concentration and electrolysis voltage, are also explored. The results show that the current distribution is concentrated in the distance of 100 $\mu \mathrm{m}$ away from electrolyte layer, and the enhancement of oxygen ionic conductivity in cathode can benefit the current density and widen the current distribution. Strengthening the cathode porous structure can improve the current density of SOEC. The feed steam fluctuations lead to the performance fluctuation of SOEC, which can reach a new equilibrium within 0.02 s after changing the operating conditions. The SOEC exhibits fast responsiveness when considering the tolerance of the structure materials, and the mass diffusion cannot be ignored in the pores.