Surface restructuring of a perovskite-type air electrode for reversible protonic ceramic electrochemical cells

One limiting factor to the high-performing reversible protonic ceramic electrochemical cells is the poor stability and electrocatalytic activity of air electrodes. Here the authors report a water-promoted surface restructuring process to enhance the performance of Ba0.9Co0.7Fe0.2Nb0.1O3-delta air electrode. Reversible protonic ceramic electrochemical cells (R-PCECs) are ideally suited for efficient energy storage and conversion; however, one of the limiting factors to high performance is the poor stability and insufficient electrocatalytic activity for oxygen reduction and evolution of the air electrode exposed to the high concentration of steam. Here we report our findings in enhancing the electrochemical activity and durability of a perovskite-type air electrode, Ba0.9Co0.7Fe0.2Nb0.1O3-delta (BCFN), via a water-promoted surface restructuring process. Under properly-controlled operating conditions, the BCFN electrode is naturally restructured to an Nb-rich BCFN electrode covered with Nb-deficient BCFN nanoparticles. When used as the air electrode for a fuel-electrode-supported R-PCEC, good performances are demonstrated at 650 degrees C, achieving a peak power density of 1.70 W cm(-2) in the fuel cell mode and a current density of 2.8 A cm(-2) at 1.3 V in the electrolysis mode while maintaining reasonable Faradaic efficiencies and promising durability.

Automated summary

Researchers enhance the performance of reversible protonic ceramic electrochemical cells by water-promoted surface restructuring, improving the electrocatalytic activity for oxygen reduction and evolution while maintaining stability and durability.