Development of scientific bases of tailor-made design of functionally graded nanocomposite cathode materials for both IT-SOFCs and PC-SOFCs

PROTON-prosjektet undersøker nye dobbeltperovskitter med blandet ionisk og elektronisk ledningsevne for bruk i oksygenelektrodene i protonledende brenselceller og elektrolysører. Disse er i dag begrenset av for høy polarisasjonsmotstand først og fremst knyttet til oksygenelektrodene. Målinger med termogravimetri viser at de nye materialene tar opp protoner og de elektrokjemiske egenskapene viser lovende resultater og stabilitet for bruk med protonledende elektrolytter for brenselceller og elektrolysører.

Basic research studies on preparation routes of cathode materials, e.g. the double perovskites Pr1-yLayBaCo2-xFexO6-d, Gd1-yLayBaCo2-xFexO6-d in wide composition range will be performed. Precise analysis of the materials properties is necessary to avoid a trial and error approach. In the project we are going to investigate oxide compositions and their morphology using X-ray (XRD), scanning electron microscopy (SEM) and energy dispersive (EDA) analyses. Measurement of overall and oxide ion conductivity of these oxides using four-probe DC method and polarization technique, respectively, depending on temperature and oxygen partial pressure and determination of the electron and oxide ion transport parameters such as charge carrier mobilities, oxide ion diffus ion coefficients, activation energy etc. The oxygen nonstoichiometry of the electrode materials will be investigated as a function of temperature and oxygen partial pressure by means of thermogravimetric (TGA) and coulometric analyses along with their def ect structure. Calculation of oxide ion transport in the double perovskite using molecular dynamic simulation and comparison these results with those measured. Study of the crystal structure vs. temperature and oxygen partial pressure and determination of the oxides lattice thermal expansion using both X-ray and dilatometric analyses. Analysis of the oxide compositions and their morphology using XRD, SEM and EDX. Investigation of thermal and chemical compatibility of the prepared cathodes with the differe nt electrolytes. Preparation of binary combinations cathode/electrolyte and performance of test measurements such as polarization resistivity - Rp. The results from this approach will allow to find the best cathode materials and to prepare single cells of solid oxide fuel cell (SOFC) and proton conductive electrolyte fuel cell (PC-SOFCs) in order to check their performance such as power, open circuit voltage etc. in test measurements under real conditions.