(450a) Nano-Sized Nio–SDC Composite Synthesized Via a Low-Temperature Hydrothermal Route in a Single Step As the Anodes of Intermediate Temperature Solid Oxide Fuel Cell

A solid oxide fuel cell (SOFC) is considered as a high efficient energy converting device for chemical energy in fuels directly to electrical energy via an electrochemical reaction, getting rid of the efficiency limit of the Carnot cycle and with minimal emission [1]. In the last two decades, a promising composite electrolyte material composed of a doped ceria phase and a binary carbonate salt phase has been tested due to its efficient ionic conductivity and promising performance in intermediate temperature SOFC [2-5]. However, the anode material of the composite electrolyte-supported SOFC has still been a challenge. In this work, homogenous nano-sized NiO-samarium doped ceria (marked as HT-NiO-SDC) composite with uniform particle size and a good sintering ability was synthesized through a low-temperature hydrothermal route, and used as the anode of SOFC with a composite electrolyte. For comparison, the conventional solid mixing sample (denoted as SM-NiO-SDC) was also prepared. The electrical performance of the single cells with the NiO-SDC anode and SDC-(Li_0.67Na_0.33)₂CO₃ composite electrolyte was investigated.

The cubic NiO phase and fluorite-structured SDC phase in the HT-NiO-SDC anode were confirmed with XRD. The diameter of the HT-NiO-SDC particle observed with SEM and TEM is around 10 nm. The electronic conductivity of HT-NiOâ??SDC cermet measured with a DC four-probe technique in H₂ is much higher than that of the conventional SM-NiO-SDC sample. Moreover, the electrochemical impedance spectroscopy result shows that the polarization resistance of HT-NiO-SDC is much lower than that of SM-NiO-SDC, indicating a homogeneous distribution of the NiO and the SDC phases in the HT-NiO-SDC sample.

Fig. 1a shows that the performance of the cell with HT-NiO-SDC anode improves with the increase of the NiO content in the anode. The maximum power density of the cell is 738 mW cm^-2 at700 ^oC, much higher than that of the cell with conventional SM-NiO-SDC anode, as shown in Fig. 1b, demonstrating that the hydrothermal synthesis is a promising method to preparing anode materials for intermediate-temperature SOFCs with a ceramic-carbonate composite electrolyte.