Tuning interfacial chemistry and electrochemical properties of solid oxide cells via cation interdiffusion

Abstract

Electrochemical performance of solid oxide cells is sensitive to electrode/electrolyte interfacial chemistry. Herein, taking SmBaCoCuO5+δ (SBCC) oxygen electrode and Gd0.1Ce0.9O1.95 (GDC) electrolyte as an example, the role of cation interdiffusion in tuning interfacial chemistry and electrochemical properties of solid oxide cells was studied. An increase in cation diffusion between SBCC and GDC layers results in bigger and better-connected SBCC particles with slight shrinkage in unit cell and denser GDC layer with distorted crystal structure. Cation diffusion is also responsible for abnormal deviation in electrochemical impedance spectroscopy that can be used to characterize catalytic properties of the electrode for oxygen redox reactions in SBCC/GDC/SBCC symmetric cell. The internal mechanism that contributes to this phenomenon was revealed through a series of well-designed tests and theoretical modeling. Single cell, SBCC/GDC/GDC-NiO, has high cation interdiffusion, works well in both solid oxide fuel cell and solid oxide electrolysis cell model; it also exhibits decreased catalytic activity and open-circuit voltage. This work provides helpful guides for the design of advanced solid oxide cells and other related devices.