Oxygen Electrode Surface Constructing for Reversible Protonic Ceramic Electrochemical Cells

Abstract

Reversible protonic ceramic electrochemical cells (R-PCECs) have great potential for energy conversion and storage at low-intermediate temperatures (400-700oC), which could enable the conversion of H2O into H2 in electrolysis (EL) mode, and inversely the production of electricity in fuel cell (FC) mode. However, the sluggish kinetics of oxygen reduction/evolution reaction (ORR/OER) at reduced temperatures, as well as undesired surface segregation and structural deterioration, have impeded the development of R-PCECs devices. In this presentation, we introduce a double-perovskite type oxygen electrode that has been optimized for enhanced reaction activity and surface stability using an efficient fluorite catalyst coating. Specifically, the oxygen electrode, PrBaCo2O5+δ (PBC), has been infiltrated with an active and durable shell, Pr0.1Ce0.9O2+δ (PCO). The obtained results show that PCO-PBC possess elevated oxygen vacancy concentration which would improve the surface exchange process, facilitate ion diffusion, and provide multiple active reaction sites, while simultaneously preventing Ba segregation during operation. Therefore, the fuel-electrode-supported single cell with a PCO-PBC oxygen electrode achieves high performance and a negligible degradation in EL and FC dual modes for 25 cycles and 100 h at 650 oC with 3vol.% H2O.