Electrochemical testing and characterization of solid oxide cells and stacks

Solid oxide cells (SOCs) are multilayer electrochemical devices capable of operating reversibly in both fuel cells and electrolysis modes, playing a key role in sustainable energy systems. This chapter provides a comprehensive overview of electrochemical testing and characterization techniques for SOCs, covering both single-cell and stack configurations. It begins with an introduction to SOC working principles and architectures, followed by DC and AC characterization methodologies. DC techniques, such as open circuit voltage and polarization curves, offer insights into overall performance and gas tightness. AC characterization focuses on electrochemical impedance spectroscopy and advanced analysis tools, including Kramers-Kronig validation, the Analysis of the Difference in Impedance Spectra, the distribution of relaxation times, and complex nonlinear least squares fitting, enabling detailed interpretation of electrochemical processes. The chapter also outlines practical testing setups and procedures, with examples from recent studies, addressing performance evaluation, load and thermal cycling, and accelerated degradation testing. It serves as a valuable resource for researchers and engineers working on SOC development and electrochemical analysis.