Chemical interaction and diffusion on interface cathode/electrolyte of SOFC

Abstract

The high-temperature solid oxide fuel cell (SOFC) is suited for the environmentally acceptable and efficient conversion of chemical into electric energy. A prerequisite for introducing this technology on the market is the controlled formation of the interface between electrodes and the electrolyte. In the case of using an electrolyte based on LaGaO₃ the formation of third phases and the diffusion of individual metallic cations from and to the electrolyte was investigated with the aid of point analyses on micrographs of the environment of the interface using quantitative EDS analysis. In case of an anode of Ni-CeO₂ cermet the mixed oxide SrLaGa₃O₇ is formed and, in addition, a relatively pronounced transport of La from the electrolyte into the CeO₂ phase was observed. A relatively strong diffusion of Mn and an even stronger diffusion of Co into the electrolyte took place between the cathode of, e.g., La_0.75Sr_0.2Mn_0.8Co_0.2O₃ and the La_0.9Sr_0.1Ga_0.8Mg_0.2O₃ electrolyte, whereas a weak transport of Ga to the cathode was identified.