Tuning electrochemical and transport processes to achieve extreme performance and efficiency in solid oxide cells

Abstract

Solid oxide cells (SOCs) have important applications as fuel cells and electrolyzers. The application for storage of renewable electricity is also becoming increasingly relevant; however, it is difficult to meet stringent area-specific resistance (ASR) and long-term stability targets needed to achieve required efficiency and cost. Here we show a new SOC that utilizes a very thin Gd-doped ceria (GDC)/yttria-stabilized zirconia (YSZ) bi-layer electrolyte, Ni-YSZ cell support with enhanced porosity, and electrode surface modification using PrOx and GDC nanocatalysts to achieve unprecedented low ASR values < 0.1 Ω cm2, fuel cell power density ∼3 W cm-2, and electrolysis current density ∼4 A cm-2 at 800 °C. Besides this exceptionally high performance, fuel cell and electrolysis life tests suggest very promising stability in fuel cell and steam electrolysis modes. Electrochemical impedance spectroscopy analysis done using a novel impedance subtraction method shows how rate-limiting electrode processes are impacted by the new SOC materials and design.