A.A. Kolchugin

The Development Of Electrolytes ForIntermediate Temperature Solid Oxide Fuel Cells

This report describes a number of experimental studies on the solid state electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFCs): Ce1–xLnxO2–δ (Ln = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb), some multicomponent systems Ce1-xLnx/2Ln x/2O2-δ (x = 0 – 0.20; Ln = Sm, La, Gd and Ln = Dy, Nd, Y), some systems with simultaneous doping by rare earth and alkali earth elements Ce0.8(Sm1-xMx)0.2O2-δ (M = Ca, Sr; x = 0.0 – 1.0) and Ce0.8(Sm1-x-yBayMx)0.2O2-δ (M = Ca, Sr; x = 0, 0.15, 0.20; y = 0.05, 0.1). Two important aspects are emphasized: the effect of different dopants’ ionic radius and concentration on the electrical properties of CeO2 based solid solutions and the influence of the method of preparation on the structural properties of ceria ceramics and the electrochemical performance of single SOFCs on their base. To describe the electrolytic properties of solid electrolytes the notation of the electrolytic domain boundary (EDB) – the critical oxygen partial pressure 2 ( ) O P  at which the values of the electronic and ionic components of conductivity are equal, were calculated and presented. The interpretation of these data will lead to a better understanding of, subsequent improvements to and ultimately, the commercialization of IT-SOFCs in Russia.

Electrical and Electrochemical Properties of La2–xCaxNiO4+δ and La2–xCaxNiO4+δ–Ce0.8Sm0.2O1.9 Cathode Materials for Intermediate Temperature SOFCs

The present work focuses on the electrical properties of La2–xCaxNiO4+δ (x=0–0.4) and the electrochemical performance of the cathodes based on these materials with a LаNi0.6Fe0.4O3-δ current collector in contact with a Ce0.8Sm0.2O1.9 electrolyte. The effect of the sintering temperature on the polarization resistance of La1.7Ca0.3NiO4+δ–Ce0.8Sm0.2O1.9 composites of different content has been studied by an impedance spectroscopy method. The composite electrode 50 wt.% La1.7Ca0.3NiO4+δ – 50 wt.% Ce0.8Sm0.2O1.9 sintered at the temperature below 1300°C has showed the lowest polarization resistance value equal to 0.27 Ωcm2 and in case of PrOx infiltration 0.033 Ωcm2 at 800°C in air.

CERIA-BASED MATERIALS FOR HIGH-TEMPERATURE ELECTROCHEMISTRY APPLICATIONS

This paper describes the experimental studies of multi-component solid state electrolytes based on CeO2 and their application in intermediate temperature electrochemical devices. Two important aspects are emphasized: the effect of different dopants’ ionic radius and concentration on the electrical properties of CeO2-based solid solutions in air and the influence of combined dopants on the electrolytic properties of solid electrolytes from the standpoint of the critical oxygen partial pressure pO2 at which point the values of the electronic and ionic components of conductivity are equal. Examples of usage of the developed multi-component Ce0.8(Sm0.75Sr0.2Ba0.05)0.2O2-δ electrolyte synthesized by solid state, laser evaporation and combustion methods and composites on the base of Ce0.8(Sm0.8Sr0.2)0.2O2−δ electrolyte as a component of electrochemical devices such as solid oxide fuel cell, gas sensors and as a component of the mixed ionic and electronic conducting (MIEC) membranes for hydrogen and syngas gas production are cited.