Highly efficient direct carbon solid oxide fuel cells operated with camellia oleifera biomass

Abstract

Direct carbon solid oxide fuel cells (DC-SOFCs), energy conversion devices with an all-solid-state structure, utilize solid carbon as a fuel to generate electricity in a green and efficient manner. Recently, the use of biomass-derived carbon as a DC-SOFC fuel has become a key research topic owing to the abundance and renewability of biomass. Thus far, for the majority of studies, an anaerobic pyrolysis process is usually needed for converting the biomass to biochar prior to applying DC-SOFCs. In this study, DC-SOFCs were assembled with perovskite-type La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) and Ag-Gd0.2Ce0.8O2-δ as the electrolyte and electrodes, respectively. The electrochemical performance and stability were evaluated for two types of DC-SOFCs: those filled with Camellia oleifera shell biomass as the fuel and those filled with biochar derived from the biomass. The biomass-filled DC-SOFC achieved a maximum power density of 306 mW cm−2 at 800°C, which is close to that of the biochar-filled DC-SOFC (317 mW cm−2). Moreover, discharge test results of constant current indicate that biomass-filled DC-SOFCs have higher fuel utilization. This study verifies the feasibility and potential of loading biomass directly into DC-SOFCs as a carbon source, and reveals that, compared with DC-SOFCs operated with biochar, biomass-filled DC-SOFCs can deliver remarkable electrochemical performance and stability. Thus, a simpler and more convenient way to generate electricity through efficient and clean utilization of biomass energy is identified.