An active and durable air electrode with self-generated nanoparticles decorated on the surface for reversible oxygen-ionic ceramic electrochemical cells

Abstract

A reversible oxygen-ionic ceramic electrochemical cell (R-OCEC) is a prospective cost-effective energy storage and conversion device for its efficient operation capability in dual modes of fuel cells (FCs) and electrolysis cells (ECs). However, the advance of R-OCEC is largely hampered by the sluggish reaction kinetics and poor durability of the oxygen reduction reactions (ORRs) and the oxygen evolution reactions (OERs) at the air electrode. Here, we develope a bifunctional air electrode for R-OCECs employing a perovskite-type oxide electrode composed of Pr_0.5Sr_0.5Co_0.9Nb_0.1O_3−δ (PSCN). After the operation, fine nanoparticles with a likely formula of SrCo_0.5Nb_0.5O_3−δ (SCN) are in situ segregated from the PSCN frame. The SCN decorated PSCN (SCN–PSCN) electrode shows an extremely small area-specific resistance (ASR) of 0.01 Ω cm² at 800 °C. When applied to R-OCEC as the air electrode, the cells achieve encouraging performance at 800 °C in both FC (a peak power density of 2.24 W cm⁻²) and EC (a current density of −1.92 A cm⁻² at 1.3 V) modes. In addition, the cells exhibit excellent durability for stable operation of over 140 h in FC mode, 100 h in EC mode, and 118 h cycling test in dual modes, respectively, indicating that SCN–PSCN is a promising air electrode material.