Investigation of the Abnormal I-V Curve Shape of Hybrid Direct Carbon Fuel Cell Using Lanthanum Strontium Calcium Titanate-Based Anode

Abstract

Solid oxide direct carbon fuel cell are being developed for use with waste derived materials. To avoid problems of the state-of-art Ni/YSZ anode, perovskite-based anode materials are being investigated. We have fabricated solid oxide fuel cells with La0.2Sr0.25Ca0.45MxTi1-xO3- δ (M=Ni, Fe, or Co) anodes, YSZ electrolyte, and LSM cathode. Electrochemical performance of these cells have been evaluated with both hydrogen and solid carbon as the fuel and promising results have been recorded. For example, fuel cells with La0.2Sr0.25Ca0.45Ni0.05Ti0.95O3- δ anode tested in hybrid direct carbon fuel cell mode reached a maxmium power density of 82.3 mW/cm2 measured in N2 purging gas at 850 °C. During hybrid direct carbon fuel cell testing with solid carbon fuel and nitrogen purging gas, I-V curves obtained showed an abnormal shape between 0.6V to 0.7 V. To investigate the origin of this line shape, we have used methods such as electrochemical impedance spectroscopy, potentiostatic study, analyzing of off gases from fuel cell using gas choromotography, SEM imaging, EDS analysis and Raman mapping of the tested fuel cell. These results can not only help explain the observed shape of I-V curve, but also provide insight into the mechanism of hybrid direct carbon fuel cells, thus benefiting further development of fuel cells for solid waste to energy applications.