The determination of the three-phase boundary width of solid oxide fuel cell cathodes by current-driven 18O tracer incorporation

For several electrode materials oxide ion incorporation into a solid electrolyte is believed to take place in a narrow zone close to the three-phase boundary (TPB). However, a determination of the width, exact location and distribution of the electrochemical activity of this incorporation zone is difficult. We discuss how far current-driven oxygen tracer experiments allow a quantification of TPB properties. The considerations are exemplified by experiments revealing the TPB width of Pt on YSZ.