Theoretical analysis of reversible solid oxide fuel cells for hydrogen and electricity generation

A single reversible solid oxide fuel cell (RSOFC) can accomplish two functions: (1) as a solid oxide steam electrolyzer (SOSE) for hydrogen production and (2) as a solid oxide fuel cell (SOFC) for power generation. A theoretical study is performed to analyze the electrochemical performance of a RSOFC with an emphasis on the concentration overpotentials. RSOFCs with oxygen ion conducting electrolyte (RSOFC-O) and proton conducting electrolyte (RSOFC-H) are studied. Theoretical solutions are derived for calculating the concentration overpotentials of RSOFCs working in the SOSE mode and SOFC mode. It is found that the oxygen electrode-supported configuration is the optimal design for an RSOFC-O working in the SOSE mode; while this design can cause consider concentration overpotential in the SOFC mode. For comparison, the hydrogen electrodesupported configuration is identified as the optimal design for both the SOFC and SOSE modes of a RSOFC-H. Therefore, a RSOFC-H has a natural advantage over a RSOFC-O in terms of cell design optimization. The modeling study signifies the difference between RSOFC-H and RSOFC-O and can serve as a useful tool for designing a RSOFC for hydrogen and electricity generation.