Kim Jung Hyun, Kang Yun Chan
Department of Chemical Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Korea.
Nanoscale. 2014 May 7;6(9):4789-95. doi: 10.1039/c3nr06651g.
Micron-sized, spherical, meso- and macro-porous Co3O4 and CoO-carbon composite powders were prepared via a simple two-step spray drying process. The CoO-carbon composite powders, in which homogeneous mixing of the metal oxide and carbon components was achieved using the first spray drying process, were wet milled to produce the slurry for the second spray drying process. Co3O4 and CoO-carbon composite powders with mean particle sizes of 4.4 and 4.7 μm were respectively obtained by spray-drying the slurry after post-treatment at 400 °C under air and nitrogen atmospheres. Meso- and macro-pores were uniformly distributed inside the Co3O4 and CoO-carbon composite powders. The CoO-carbon composite powders exhibited discharge capacities of 882 and 855 mA h g(-1) at a high constant current density of 1400 mA g(-1) for the 2(nd) and 100(th) cycles. The discharge capacities of the Co3O4 powders at the 2(nd) and 100(th) cycles were 970 and 644 mA h g(-1). With stepwise increment in the current density from 500 to 5000 mA g(-1), the discharge capacities of the CoO-carbon composite powders decreased slightly from 985 to 698 mA h g(-1). The superior rate and cycling performances of the CoO-carbon composite powders are ascribed to their meso- and macro-porous structures and carbon components.
通过简单的两步喷雾干燥工艺制备了微米级球形中孔和大孔Co3O4及CoO-碳复合粉末。在第一步喷雾干燥过程中实现了金属氧化物和碳组分均匀混合的CoO-碳复合粉末，经过湿磨以制备用于第二步喷雾干燥过程的浆料。在空气和氮气气氛下于400℃进行后处理后，通过对浆料进行喷雾干燥，分别获得了平均粒径为4.4和4.7μm的Co3O4及CoO-碳复合粉末。中孔和大孔均匀分布在Co3O4及CoO-碳复合粉末内部。CoO-碳复合粉末在第2次和第100次循环时，在1400 mA g(-1)的高恒电流密度下表现出882和855 mA h g(-1)的放电容量。Co3O4粉末在第2次和第100次循环时的放电容量分别为970和644 mA h g(-1)。随着电流密度从500逐步增加到5000 mA g(-1)，CoO-碳复合粉末的放电容量从985略微降低至698 mA h g(-1)。CoO-碳复合粉末优异的倍率性能和循环性能归因于其介孔和大孔结构以及碳组分。
