NiCo₂O₄纳米花/ECNFs复合分级结构材料制备及电化学性能研究

Preparation and Electrochemical Properties of NiCo₂O₄ Nano-Flower/ECNFs Composite Hierarchical Structure Materials

摘要: 高性能电极材料是未来超级电容器性能提升的关键。本文以电纺碳纳米纤维(ECNFs)为基底，结合水热技术制备了仿梅花状分级结构NiCo₂O₄纳米花/ECNFs复合材料。采用SEM、XPS、XRD和TEM对材料的物性和结构进行了表征。在三电极体系碱性电解液条件下，测试了样品的电化学性能，结果表明，复合材料比单一材料的电容性能更好，在6 mol∙L⁻¹的KOH电解液中，0.1 A∙g⁻¹电流密度下，比电容高达884 F∙g⁻¹，且具有很好的稳定性(4 A∙g⁻¹电流密度下循环7500次，比容量保持在93.4%)。增强的电化学性能可归结为两方面原因：一方面由于二维NiCo₂O₄纳米片组装的三维纳米花复合一维炭纳米纤维的混合结构特性，增强了电解液与电极材料的接触面积，从而提高了电荷存储的有效空间；另一方面由于ECNFs双电层电容叠加NiCo₂O₄的赝电容特性，提高了材料的整体电容量。

Abstract: High performance electrode materials are the key to the performance improvement of super capacitors in the future. In this paper, a plum-like hierarchical structure NiCo₂O₄ nano-flower/electrospun carbon nanofibers (ECNFs) composite material was prepared by electrospinning technology combined with hydrothermal technology. The physical properties and structure were characterized by SEM, XPS, XRD and TEM. The electrochemical properties of the samples were tested in alkaline electrolyte with a three-electrode system. The results showed that the capacitance of the composite was better than that of the single material. The hybrid NiCo₂O₄ nano-flower/ECNFs electrode exhibited a high capacitance of 884 F∙g⁻¹ at a current density of 0.1 A∙g⁻¹ in 6 mol∙L⁻¹ KOH aqueous solution, and good cycling stability (93.4 % retention after 7500 cycles at a high current density of 4 A∙g⁻¹). The enhanced electrochemical properties can be attributed to two factors: on the one hand, the contact area between electrolyte and electrode material is enhanced due to the mixed structure of 3D nano-flower and 1D carbon nanofibers assembled by 2D NiCo₂O₄ nanoflakes, and on the other hand, the contact area between electrolyte and electrode material is enhanced due to the mixed structure of 3D nano-flower and 1D carbon nanofibers, on the other hand, the pseudo-capacitance of ECNFs double-layer capacitor superimposed with NiCo₂O₄ increases the overall capacitance of the material.