ハイブリッドナノ粒子の合成に基づく三次元機能界面の創成

抄録

Three-dimensionally extended functional interfaces were built using hybrid nanoparticles synthesized by the unique break-down and bottom-up approaches. Here, we report the processes in detail and the applications of the hybrid nanoparticles for high performance solid oxide fuel cells (SOFCs). The first generation NiO/yttria-stabilized zirconia (YSZ) hybrid nanoparticles (～100nm) was fabricated by a dry mechanochemical process without milling media. The nanoparticles provide the uniform three-dimensional networks of Ni, YSZ and pore phases suggesting the formation of large amount of triple phase boundaries (TPBs) in Ni/YSZ anode. The anode showed the performance high enough for the practical applications and good long-term stability at 700℃. More uniform Ni/YSZ anode microstructure and resultant better performance were achieved using the second generation NiO/YSZ hybrid nanoparticles (＜100nm) synthesized via a modified co-precipitation of hydroxides. We found that the homogeneous hybrid nanoparticles can be synthesized at pH >13 through this method. For further higher performance of the SOFCs, we newly developed a co-precipitation method of third　generation NiO/YSZ and (La_0.85Sr_0.15)_0.98MnO₃(LSM)/YSZ hybrid nanocrystals (＜10nm) using YSZ nanocrystals of ca. 3nm, perfectly dispersed in aqueous medium, as the seed crystals. The obtained hybrid nanocrystals successfully forms nanostructured electrodes consisting of the homogeneously distributing nanosized grains. The homogeneous nanostructure provides huge amount of the functional interfaces within the electrodes. Finally, SOFC consisting of the nanostructured electrodes showed the very high power density of 0.18, 0.40, 0.70 and 0.86 W·cm^-2 at 650, 700, 750 and 800℃, respectively, under the constant cell voltage of 0.7 V.