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_0.5Sr_0.5Co_0.8Fe_0.2O_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_0.4Sr_0.5Cs_0.1Co_0.7Fe_0.2M_0.1O_3−δ (M═Ni, Zr) consisted of the major perovskite phase and surface‐enriched NiO and BaZrO₃ minor phases. When Ba_0.4Sr_0.5Cs_0.1Co_0.7Fe_0.2Ni_0.1O_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_0.4Sr_0.5Cs_0.1Co_0.7Fe_0.2Zr_0.1O_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; BaZrO₃ nanoparticles increase steam adsorption and hydration capacity. This study provides a new idea for designing efficient and durable air electrodes of ceramic cells.