Research on Current Density Overshoot of Reversible Solid Oxide Cell During Mode Switching

Reversible solid oxide cell (RSOC) is a device with both power generation and hydrogen production capacities. Current density overshoot (CDO) occurs in the mode switching process of RSOC, which has adverse effects on RSOC life and power generation efficiency. In this paper, the generation mechanism of overshoot is further studied. Building on the fact that substance transport in both fuel channel and air channel is slower than the electrochemical response, simulation results show that increasing the mole fraction of H
2
O at the inlet of fuel channel can reduce the overshoot during the process of fuel cell (FC) mode switching to electrolysis cell (EC) mode and increase the overshoot of the opposite switching direction. In addition, under different switching modes, the relationship between CDO and voltage variation is uncertain. This paper considers fixed initial state or final state voltage respectively and draws different conclusions: There is a positive correlation between CDO and voltage variation at fixed final state voltage, but no positive correlation at fixed initial state voltage.