Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin, 150001, PR China.
Dalton Trans. 2013 Nov 28;42(44):15706-15. doi: 10.1039/c3dt51826d.
A novel flower-on-sheet hierarchical morphology of α-Co(OH)2 nanostructures was achieved via an easy two-step synthesis strategy. The method is based on first a galvanostatic electrodeposition (GE) of vertically aligned interconnected Co(OH)2 nanosheets to form a branch layer and second a potentiostatic electrodeposition (PE) of Co(OH)2 microflowers on the obtained branch layer from the secondary growth of their sheet-like precursors. The formation mechanism of this special PE time-dependent nanostructure was proposed and their morphology-dependent supercapacitor properties were also investigated. For a given areas mass loading, high specific capacitances of 1822 F g(-1) have been achieved for the electrode obtained after 200 s GE followed by a 300 s PE in a three-electrode configuration, and it maintained 91% of its initial capacity after 1000 constant-current charge/discharge cycles. Even when the discharge current density was increased from 1 to 50 mA cm(-2), the capacitance was still as high as 1499 F g(-1), indicating an excellent rate performance of the fabricated electrodes. The high performances of the electrodes are attributed to the special porous structure, 3D hierarchical morphology, vertical aligned orientation, and low contact resistance between active material and charge collector.
通过一种简单的两步合成策略，实现了α-Co(OH)2 纳米结构的新型花状层状形态。该方法基于首先进行恒电流电沉积（GE）以垂直排列的相互连接的 Co(OH)2 纳米片形成分支层，然后在所得分支层上通过其片状前体的二次生长进行电势控制电沉积（PE）以形成 Co(OH)2 微花。提出了这种特殊的 PE 时间依赖型纳米结构的形成机制，并研究了其形态依赖的超级电容器性能。对于给定的面积质量负载，在三电极配置中，经过 200 s 的 GE 随后进行 300 s 的 PE 后，获得的电极的比电容为 1822 F g-1，在 1000 次恒流充放电循环后保持其初始容量的 91%。即使将放电电流密度从 1 增加到 50 mA cm-2，电容仍高达 1499 F g-1，表明所制备的电极具有优异的倍率性能。电极的高性能归因于特殊的多孔结构、3D 分层形态、垂直排列取向以及活性材料与电荷收集器之间的低接触电阻。
