Constructing Robust and Efficient Ceramic Cells Air Electrodes Through Collaborative Optimization Bulk and Surface Phases

Abstract Slow reaction kinetics of air electrodes is a common problem faced by low‐temperature (<650 °C) oxygen‐ion conducting solid oxide fuel cells (O‐SOFCs) and proton‐conducting reversible proton ceramic cells (R‐PCCs). Here, an innovative approach is proposed to design and prepare two efficient and durable Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF)‐based nanocomposites through self‐reconstruction strategy, which aim to optimize both the bulk and surface properties of electrode materials simultaneously. Specifically, the two nanocomposites with a nominal composition of Ba 0.4 Sr 0.5 Cs 0.1 Co 0.7 Fe 0.2 M 0.1 O 3−δ (M═Ni, Zr) consisted of the major perovskite phase and surface‐enriched NiO and BaZrO 3 minor phases. When Ba 0.4 Sr 0.5 Cs 0.1 Co 0.7 Fe 0.2 Ni 0.1 O 3−δ (BSCsCFNi) is used as an air electrode in O‐SOFCs, the peak power density is 1.36 W cm −2 at 650 °C; while Ba 0.4 Sr 0.5 Cs 0.1 Co 0.7 Fe 0.2 Zr 0.1 O 3−δ (BSCsCFZr) is used in R‐PCCs, a peak power density of 1.24 W cm −2 and a current density of −1.98 A cm −2 (1.3 V) are achieved at 650 °C, and exhibits stable reversibility over 100 h. Theoretical calculations and experiments indicate that Cs + doping enhances the bulk conduction of oxygen ions and protons; NiO nanoparticles enhance oxygen adsorption and surface exchange; BaZrO 3 nanoparticles increase steam adsorption and hydration capacity. This study provides a new idea for designing efficient and durable air electrodes of ceramic cells.