Numerical Analysis of Multi‐Field Coupling Transient Response Mechanism in Mode‐Switching Process of Reversible Solid Oxide Cell

In this article, a three‐dimensional (3‐D) dynamic model of a single repeating unit of reversible solid oxide cell (RSOC) is developed and validated. On the basis of the model, the spatiotemporal evolution of key parameters—including current density, power density, gas concentration, and temperature—is systematically analyzed during both solid oxide fuel cell (SOFC)–solid oxide electrolysis cell (SOEC) (fuel cell mode to electrolyzer mode) and SOEC–SOFC (electrolyzer mode to fuel cell mode) switching processes, elucidating the multiphysics coupling mechanisms involved. The effects of boundary conditions and control parameters such as hydrogen mole fraction (), operating temperature ( T in ), operating voltage ( V FC / V EC ), and switching time (Δ τ ) on transient performance are further analyzed. The results show that the SOFC–SOEC switching shows current and power overshoot, while the SOEC–SOFC switching responds faster without overshoot but fluctuates. In the gas concentration response, H 2 O is prone to overshoot, and there is an obvious concentration gradient in the electrode. The temperature response is slower than the electrochemical response, and the temperature change in the central area is the most significant. Parameter analysis shows that properly increasing , V FC and prolonging Δ τ can effectively improve the switching stability. Although increasing T in can help to improve the power density, it will aggravate the temperature gradient and weaken the response stability. This study offers critical insights into the dynamic behavior of RSOC during mode switching and lays a theoretical foundation for optimizing its operational strategy and system design.