Pulsed electrolysis of carbon dioxide by large-scale solid oxide electrolytic cells for intermittent renewable energy storage

CO₂ electrolysis with solid oxide electrolytic cells (SOECs) using intermittently available renewable energy has potential applications for carbon neutrality and energy storage. In this study, a pulsed current strategy is used to replicate intermittent energy availability, and the stability and conversion rate of the cyclic operation by a large-scale flat-tube SOEC are studied. One hundred cycles under pulsed current ranging from −100 to −300 mA/cm² with a total operating time of about 800 h were carried out. The results show that after 100 cycles, the cell voltage attenuates by 0.041%/cycle in the high current stage of −300 mA/cm², indicating that the lifetime of the cell can reach up to about 500 cycles. The total CO₂ conversion rate reached 52%, which is close to the theoretical value of 54.3% at −300 mA/cm², and the calculated efficiency approached 98.2%, assuming heat recycling. This study illustrates the significant advantages of SOEC in efficient electrochemical energy conversion, carbon emission mitigation, and seasonal energy storage.