REBaCo2O5+δ layered perovskite oxide compounds (RE = Rare Earth ion) are promising cathodes for Intermediate Temperature SOFCs. In this work, a simple and cost-effective co-precipitation synthesis in aqueous medium was applied to prepare LaBaCo2O5+δ (LBC) and YBaCo2O5+δ (YBC) cathodes. The chemical and electrochemical properties of both materials were characterized by means of different techniques (XRD, SEM, TPO, TG-DTA, 4-probe DC conductivity measurement, EIS tests on symmetric cells). The coprecipitation synthesis revealed a promising route to prepare perovskitic cathodes: for both LBC and YBC, the measured Area Specific Resistance values were well comparable or lower than those reported in the literature for the same materials prepared via different routes. In the case of LBC (i.e. the most active of the two materials), a kinetic investigation was performed between 600 and 800°C, at varying the O2 partial pressure (5 – 100% O2 v/v), whose results were analyzed based on equivalent circuits. The main reaction steps were identified (oxygen diffusion and charge transfer at high frequency, O2 chemisorption at medium frequency), and their activation energy and O2 reaction order were quantified. Ageing tests (500 h time on stream, 500 – 800°C) revealed quick and strong deactivation in the case of YBC, caused by interactions with the electrolyte (LSGM) and instability of the perovskite structure. In the case of LBC, good stability was observed with limited increase of the polarization resistance.
Electrical characterization of co-precipitated LaBaCo2O5+δ and YBaCo2O5+δ oxides
PELOSATO, Renato;NATALI SORA, Isabella;
2014-01-01
Abstract
REBaCo2O5+δ layered perovskite oxide compounds (RE = Rare Earth ion) are promising cathodes for Intermediate Temperature SOFCs. In this work, a simple and cost-effective co-precipitation synthesis in aqueous medium was applied to prepare LaBaCo2O5+δ (LBC) and YBaCo2O5+δ (YBC) cathodes. The chemical and electrochemical properties of both materials were characterized by means of different techniques (XRD, SEM, TPO, TG-DTA, 4-probe DC conductivity measurement, EIS tests on symmetric cells). The coprecipitation synthesis revealed a promising route to prepare perovskitic cathodes: for both LBC and YBC, the measured Area Specific Resistance values were well comparable or lower than those reported in the literature for the same materials prepared via different routes. In the case of LBC (i.e. the most active of the two materials), a kinetic investigation was performed between 600 and 800°C, at varying the O2 partial pressure (5 – 100% O2 v/v), whose results were analyzed based on equivalent circuits. The main reaction steps were identified (oxygen diffusion and charge transfer at high frequency, O2 chemisorption at medium frequency), and their activation energy and O2 reaction order were quantified. Ageing tests (500 h time on stream, 500 – 800°C) revealed quick and strong deactivation in the case of YBC, caused by interactions with the electrolyte (LSGM) and instability of the perovskite structure. In the case of LBC, good stability was observed with limited increase of the polarization resistance.File | Dimensione del file | Formato | |
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