Multilayer Nanoarchitectured Air Electrodes for High-Performance Solid Oxide Cells

Solid oxide cells (SOCs) for fuel cell and electrolysis applications are promising technologies for transitioning the current fossil-fuel-based technologies to a hydrogen-based economy. Despite extensive efforts to discover and design novel materials for SOC components, achieving both high performance and long-term stability remains a significant challenge. Here, we report a facile nanoarchitectural strategy employing multilayer combinations of room-temperature-grown nanoporous La_0.6Sr_0.4CoO_3-δ and nanoporous gadolinia-doped ceria (GDC, Ce_0.9Gd_0.1O_2-δ), configured either as single-phase layers or nanocomposites, as alternative air electrodes in SOCs. The integration of these nanostructured multilayers into practical Ni-YSZ electrode-supported cells achieved a significant reduction in electrode polarization resistance, resulting in superior performance in both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) operation compared to conventionally sintered electrodes. For the optimized multilayer nanoarchitecture, current densities as high as ∼2.3 A/cm² at 0.8 V in SOFC mode and ∼1.7 A/cm² at 1.3 V in SOEC mode at 700 °C are attained, surpassing the performance of state-of-the-art cells utilizing conventional electrodes by approximately 50 and 40%, respectively. Tests conducted in both SOFC and SOEC operation for up to ∼160 h also demonstrated good stability of the multilayer nanoarchitecture while retaining high performance. This study underscores the substantial benefits of nanoarchitectural structuring of air electrodes, demonstrating its potential to significantly enhance performance with long-term stability in SOC applications.