物理化学学报2020，Vol.36Issue(7)：25-30,6.DOI:10.3866/PKU.WHXB201903046
基于NiCo2O4纳米片电极的非对称混合电容器
Asymmetric Hybrid Capacitor Based on NiCo2O4 Nanosheets Electrode
摘要
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.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Key words
NiCo2O4 nanosheet/Electrochemical performance/Asymmetrical supercapacitor/Cathode material/Cycle stability分类
化学化工引用本文复制引用
佟永丽,戴美珍,邢磊,刘恒岐,孙婉婷,武祥..基于NiCo2O4纳米片电极的非对称混合电容器[J].物理化学学报,2020,36(7):25-30,6.基金项目
The project was supported by the Research Project of Guangdong Province Key Laboratory of Display Material and Technology, China (2017B030314031). 广东省显示材料与技术重点实验室开放课题(2017B030314031)资助项目 （2017B030314031）
