Synthèse et caractérisations électrochimiques de nouveaux matériaux pour anodes d'électrolyseurs à haute température

摘要

High temperature steam electrolysis (HTSE) is a way to produce hydrogen with a high purity, with noteworthy efficiency and without CO2 emission. Nowadays, a blocking point concerning this technology is the high overvoltage related to the oxidation of the O2- ions occurring at the oxygen electrode (anode). The aim of this work was to design new anode materials with mixed conducting properties (i.e. electronic and ionic), in order to obtain larger reaction areas and to lessen this overvoltage. In this aim, eight compounds (ferrites and rare earth nickelates) were investigated. After synthesis and shaping, these compounds were characterized using physical, chemical and electrochemical analyses in symmetrical half cells, under single atmosphere, in order to determine which ones have the best properties under zero current and under anodic polarization. Four compounds of structure derived from K2NiF4-type were then selected to be more accurately characterized in complete electrolyte supported cells, under HTSE conditions (750 - 850°C). It was then possible to obtain, for a 1.3 V cell voltage, a current density of 0.9 A/cm² at 850°C, which is nearly two times larger than the one obtained with a same cell including a commercial composite material based on strontium substituted LaMnO3 as anode.