Enhancing the Electrochemical Performance in Symmetrical Solid Oxide Cells through Nanoengineered Redox-Stable Electrodes with Exsolved Nanoparticles

Symmetrical solid oxide cells (SSOCs) have recently gained significant attention for their potential in energy conversion due to their simplified cell configuration, cost-effectiveness, and excellent reversibility. However, previous research efforts have mainly focused on improving the electrode performance of perovskite-type electrodes through different doping strategies, neglecting microstructural optimization. This work presents novel approaches for the nanostructural tailoring of (La_0.8Sr_0.2)_0.95Fe_1-xTi_xO_3-δ (LSFT_x, x = 0.2 and 0.4) electrodes using a single-step spray-pyrolysis deposition process. By incorporating these electrodes into a Ce_0.9Gd_0.1O_1.95 (CGO) porous backbone or employing a nanocomposite architecture with nanoscale particle size, we achieved significant improvements in the polarization resistance (R_p) compared with traditional screen-printed electrodes. To further boost the fuel oxidation performance, a Ni-doping strategy, coupled with meticulous microstructural optimization, was implemented. The exsolution of Ni nanoparticles under reducing conditions resulted in remarkable R_p values as low as 0.34 and 0.11 Ω cm² in air and wet H₂ at 700 °C, respectively. Moreover, an electrolyte-supported cell with symmetrical electrodes demonstrated a stable maximum power density of 617 mW cm^-2 at 800 °C. These findings highlight the importance of combining electrode composition optimization with advanced morphology control in the design of highly efficient and durable SSOCs.