物理化学学报 >> 2020, Vol. 36 >> Issue (7): 1903046.doi: 10.3866/PKU.WHXB201903046

所属专题: 纳米复合材料

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基于NiCo2O4纳米片电极的非对称混合电容器

佟永丽, 戴美珍, 邢磊, 刘恒岐, 孙婉婷, 武祥()   

  • 收稿日期:2019-03-19 录用日期:2019-04-19 发布日期:2020-03-21
  • 通讯作者: 武祥 E-mail:wuxiang05@163.com
  • 基金资助:
    广东省显示材料与技术重点实验室开放课题(2017B030314031)

Asymmetric Hybrid Capacitor Based on NiCo2O4 Nanosheets Electrode

Yongli Tong, Meizhen Dai, Lei Xing, Hengqi Liu, Wanting Sun, Xiang Wu()   

  • Received:2019-03-19 Accepted:2019-04-19 Published:2020-03-21
  • Contact: Xiang Wu E-mail:wuxiang05@163.com
  • Supported by:
    the Research Project of Guangdong Province Key Laboratory of Display Material and Technology, China(2017B030314031)

摘要:

在这项工作中,我们采用简单的水热方法在泡沫镍基底上生长了钴酸镍纳米片。结果表明,合成的NiCo2O4纳米片直接用作超级电容器电极,呈现出优异的电化学性能。在电流密度为1 mA·cm-2时,其面积比电容达到1.26 C·cm-2;经过10000次充放电循环后,其比电容仍能保持初始容量的97.6%。以NiCo2O4纳米片为正极,活性炭为负极组装的超级电容器在功率密度为1.56和4.5 W·cm-3时,其能量密度分别达到0.14和0.09 Wh·cm-3。经过10000次循环后,器件仍能保持初始比电容的95%。以上结果证明合成的钴酸镍纳米片电极在未来的储能器件中具有良好的电化学应用前景。

关键词: NiCo2O4纳米片, 电化学性能, 不对称超级电容器, 正极材料, 循环稳定性

Abstract:

The looming global energy crisis and ever-increasing energy demands have catalyzed the development of renewable energy storage systems. In this regard, supercapacitors (SCs) have attracted widespread attention because of their advantageous attributes such as high power density, excellent cycle stability, and environmental friendliness. However, SCs exhibit low energy density and it is important to optimize electrode materials to improve the overall performance of these devices. Among the various electrode materials available, spinel nickel cobaltate (NiCo2O4) is particularly interesting because of its excellent theoretical capacitance. Based on the understanding that the performances of the electrode materials strongly depend on their morphologies and structures, in this study, we successfully synthesized NiCo2O4 nanosheets on Ni foam via a simple hydrothermal route followed by calcination. The structures and morphologies of the as-synthesized products were characterized by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller (BET) surface area analysis, and the results showed that they were uniformly distributed on the Ni foam support. The surface chemical states of the elements in the samples were identified by X-ray photoelectron spectroscopy. The as-synthesized NiCo2O4 products were then tested as cathode materials for supercapacitors in a traditional three-electrode system. The electrochemical performances of the NiCo2O4 electrode materials were studied and the area capacitance was found to be 1.26 C·cm-2 at a current density of 1 mA·cm-2. Furthermore, outstanding cycling stability with 97.6% retention of the initial discharge capacitance after 10000 cycles and excellent rate performance (67.5% capacitance retention with the current density from 1 to 14 mA·cm-2) were achieved. It was found that the Ni foam supporting the NiCo2O4 nanosheets increased the conductivity of the electrode materials. However, it is worth noting that the contribution of nickel foam to the areal capacitance of the electrode materials was almost zero during the charge and discharge processes. To further investigate the practical application of the as-synthesized NiCo2O4 nanosheets-based electrode, a device was assembled with the as-prepared samples as the positive electrode and active carbon (AC) as the negative electrode. The assembled supercapacitor showed energy densities of 0.14 and 0.09 Wh·cm-3 at 1.56 and 4.5 W·cm-3, respectively. Furthermore, it was able to maintain 95% of its initial specific capacitance after 10000 cycles. The excellent electrochemical performance of the NiCo2O4 nanosheets could be ascribed to their unique spatial structure composed of interconnected ultrathin nanosheets, which facilitated electron transportation and ion penetration, suggesting their potential applications as electrode materials for high performance supercapacitors. The present synthetic route can be extended to other ternary transition metal oxides/sulfides for future energy storage devices and systems.

Key words: NiCo2O4 nanosheet, Electrochemical performance, Asymmetrical supercapacitor, Cathode material, Cycle stability

MSC2000: 

  • O646