Thermal management of solid oxide electrolysis cell under dynamic electrothermal self-balancing strategy

Solid oxide electrolysis cell (SOEC) is a prospective technology for converting renewable energy into hydrogen to achieve carbon neutrality. However, the large temperature gradient caused by the non-uniform temperature distribution inside SOEC may cause its severe performance degradation and even thermomechanical failure. To solve this issue, this study employs a novel dynamic electrothermal self-balancing strategy that enables SOEC to switch between electrolysis cell (EC) mode and fuel cell (FC) mode with high frequency to alleviate the temperature variation and reduce the temperature gradient. The effects of the thermal matching between EC mode and FC mode on the temperature variation and performance of the SOEC are analyzed first, and it is found that the net heat consumption of the SOEC is reduced by 82.63% compared with that under the traditional electrolysis operation, thus reducing the average temperature reduction and maximum temperature gradient by 72.95% and 59.85% respectively. Then, the sensitivity analysis is carried out to investigate the effects of key parameters under the dynamic electrothermal self-balancing operation on the temperature variation and performance of the SOEC. The results indicate that the increment in the EC mode voltage, EC mode time fraction, and feed flow rate can increase hydrogen production and obtain a minimum temperature gradient; the increment in the FC mode voltage and EC mode time fraction and the decrement in the EC mode voltage and feed hydrogen concentration can improve electrical efficiency; the increment in the air-feed ratio contributes to reducing the temperature gradient and improving the hydrogen production and electrical efficiency; the higher switching frequency has a positive effect on the stable operation of the SOEC. The present work reveals the mechanism of the dynamic electrothermal self-balancing operation strategy and brings new insights into SOEC thermal management.