Choi Seung Ho, Kang Yun Chan
Department of Chemical Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701 (Korea), Fax: (+82) 2 4583504.
ChemSusChem. 2013 Nov;6(11):2111-6. doi: 10.1002/cssc.201300300. Epub 2013 Jul 31.
The electrochemical properties of yolk-shell-structured, multi-component, transition-metal oxides have not yet been properly compared to those of hollow-structured or nanoscale powders. In this study, yolk-shell, hollow, and single-crystalline ZnCo2 O4 powders with uniform compositions are prepared by using simple gas-phase reaction methods. Double-shelled ZnCo2 O4 yolk-shell powder is prepared directly from the spray solution by using spray pyrolysis. Single-crystalline ZnCo2 O4 nanopowder is prepared by means of flame spray pyrolysis. The yolk-shell ZnCo2 O4 powder shows higher charge and discharge capacities than the hollow and single-crystalline powders. The yolk-shell, hollow, and single-crystalline ZnCo2 O4 powders deliver discharge capacities of 753, 586, and 206 mAh g(-1) , respectively, after 200 cycles at a charge/discharge rate of 3 A g(-1) , and the corresponding capacity retentions measured after the first cycle are 99, 74, and 27 %, respectively. The yolk-shell ZnCo2 O4 powders are structurally stable during cycling and have good electrochemical properties even at high current densities.
蛋黄壳结构的多组分过渡金属氧化物的电化学性能尚未与中空结构或纳米级粉末的电化学性能进行恰当比较。在本研究中，通过简单的气相反应方法制备了具有均匀组成的蛋黄壳、中空和单晶ZnCo₂O₄粉末。采用喷雾热解法直接从喷雾溶液中制备出双层ZnCo₂O₄蛋黄壳粉末。通过火焰喷雾热解法制备了单晶ZnCo₂O₄纳米粉末。蛋黄壳ZnCo₂O₄粉末表现出比中空和单晶粉末更高的充放电容量。在3 A g⁻¹的充放电速率下循环200次后，蛋黄壳、中空和单晶ZnCo₂O₄粉末的放电容量分别为753、586和206 mAh g⁻¹，并且在第一个循环后测得的相应容量保持率分别为99%、74%和27%。蛋黄壳ZnCo₂O₄粉末在循环过程中结构稳定，即使在高电流密度下也具有良好的电化学性能。
