Substrate Dependent Self-Organization of Mesoporous Cobalt Oxide Nanowires with Remarkable Pseudocapacitance
Substrate Dependent Self-Organization of Mesoporous Cobalt Oxide Nanowires with Remarkable Pseudocapacitance
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DOI：
10.1021/nl300779a
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发表时间：
2012-05-01
期刊：
影响因子：
10.8
通讯作者：
Alshareef, H. N.
中科院分区：
文献类型：
--
作者：
Rakhi, R. B.;Chen, Wei;Alshareef, H. N.
介孔钴氧化物纳米线的集流体依赖性自组织方案已被用于创建独特的超级电容器电极，其中每个纳米线与集流体直接接触。所制造的电极提供了所需的大孔隙率性质，以允许电解质容易流动，从而降低了装置电阻和具有大表面积的纳米孔隙率，以允许更快的反应动力学。在碳纤维纸收集器上生长的Co 3 O 4纳米线自组织成刷状形态，纳米线完全包围碳微纤维芯。相比之下，生长在平面石墨化碳纸收集器上的Co 3 O 4纳米线自组织成花状形态。在三电极配置中，刷状和花状形貌在1A/g的恒定电流密度下分别表现出1525和1199 F/g的比电容值。在两个电极配置中，刷状纳米线形态导致上级超级电容器性能，在0.25 A/g下具有911 F/g的高比电容，在40 A/g下具有784 F/g的高比电容。相比之下，花状形态表现出较低的比电容值，在0.25 A/g下为620 F/g，在40 A/g下为423 F/g。具有刷状形貌的Co 3 O 4纳米线具有高的比功率（71 kW/kg）和比能量（81 Wh/kg）。最大能量和功率密度计算的花状形态的Co 3 O 4纳米线分别为55 Wh/kg和37 kW/kg。两种电极设计通过在5000次连续充电-放电循环后保持其最大电容的91-94%而表现出优异的循环稳定性。
A scheme of current collector dependent self-organization of mesoporous cobalt oxide nanowires has been used to create unique supercapacitor electrodes, with each nanowire making direct contact with the current collector. The fabricated electrodes offer the desired properties of macroporosity to allow facile electrolyte flow, thereby reducing device resistance and nanoporosity with large surface area to allow faster reaction kinetics. Co3O4 nanowires grown on carbon fiber paper collectors self-organize into a brush-like morphology with the nanowires completely surrounding the carbon microfiber cores. In comparison, Co3O4 nanowires grown on planar graphitized carbon paper collectors self-organize into a flower-like morphology. In three electrode configuration, brush-like and flower-like morphologies exhibited specific capacitance values of 1525 and 1199 F/g, respectively, at a constant current density of 1 A/g. In two electrode configuration, the brush-like nanowire morphology resulted in a superior supercapacitor performance with high specific capacitances of 911 F/g at 0.25 A/g and 784 F/g at 40 A/g. In comparison, the flower-like morphology exhibited lower specific capacitance values of 620 F/g at 0.25 A/g and 423 F/g at 40 A/g. The Co3O4 nanowires with brush-like morphology exhibited high values of specific power (71 kW/kg) and specific energy (81 Wh/kg). Maximum energy and power densities calculated for Co3O4 nanowires with flower-like morphology were 55 Wh/kg and 37 kW/kg respectively. Both electrode designs exhibited excellent cycling stability by retaining similar to 91-94% of their maximum capacitance after 5000 cycles of continuous charge-discharge.