Abstract:

In this work, nitrogen doped carbon nanofibers (NCNF) were prepared by electrospinning and high-temperature carbonization treatment, and nickel cobalt layered double hydroxide (NiCo-LDH) nanosheets were in-situ grown on the surface of NCNF through two step solvothermal reaction to produce NCNF/NiCo-LDH/NiCo-LDH composite electrode. The morphology and structure of composite electrode were observed and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and raman spectroscopy (Raman). Cyclic voltammetry (CV), constant current charge and discharge (GCD) and AC impedance (EIS) were used to investigate the electrochemical properties of composite electrode. As a result, the nanosheet array composed of large and small sheet could be formed on NCNF, the loading of active substances could be increased effectively, the agglomeration of NiCo-LDH could be inhibited, and the dispersion and electrochemical active area of NiCo-LDH on NCNF could be enhanced through the two-step solvothermal reaction. The NCNF/NiCo-LDH/NiCo-LDH composite electrode demonstrated the superior electrochemical properties. The specific capacitance can reach 2898.7F/g at 1A/g, the capacitance retention rate was 78.4% at 10A/g, and after 6000 charge-discharge cycles, the capacitance retention was as high as 92.3%. An asymmetric supercapacitor (ASC) assembled using NCNF/NiCo-LDH/NiCo-LDH and activated carbon (AC) had a high energy density of up to 69.1W·h/kg with a power density of 743.6W/kg, and the capacitance retention was 93.4% after 6000 charge-discharge cycles at 10A/g. Therefore, the NCNF/NiCo-LDH/NiCo-LDH composite could be as promising electrode material for supercapacitor.

Key words: nickel cobult layered dovble hydroxide (NiCo-LDH), nanosheet, electrospinning, nitrogen doped carbon nanofiber, supercapacitor

摘要：

利用静电纺丝技术和高温碳化法制备氮掺杂碳纳米纤维（NCNF），通过两步溶剂热法在NCNF表面原位生长镍钴氢氧化物（NiCo-LDH）纳米片阵列，制备出NCNF/NiCo-LDH/NiCo-LDH复合电极。采用扫描电子显微镜（SEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和拉曼光谱（Raman）观察和分析复合电极的微观形貌和结构组成，并通过循环伏安（CV）、充放电（GCD）和交流阻抗（EIS）等技术研究复合电极的电化学性能。结果表明，两步溶剂热法在NCNF上构成由大片和小片交错连接的纳米片阵列，不仅有效提高了活性物质负载量，而且抑制了NiCo-LDH的团聚，增加了NiCo-LDH在NCNF上的分散性和电化学活性面积，所形成的NCNF/NiCo-LDH/NiCo-LDH复合电极在1A/g电流密度下的比电容为2898.7F/g；在10A/g高电流密度下，电容保持率可达到78.4%；连续充放电循环6000次后，电容保持率高达92.3%。以NCNF/NiCo-LDH/NiCo-LDH和活性炭（AC）组装的非对称超级电容器（NCNF/NiCo-LDH/NiCo-LDH//AC）在743.6W/kg功率密度下，具有69.1W·h/kg的高能量密度，10A/g下充放电循环6000次后，比电容能够保留初始值的93.4%。综合表明，NCNF/NiCo-LDH/NiCo-LDH复合电极是一种极具潜力的超级电容器电极材料。

关键词: 镍钴氢氧化物, 纳米片, 静电纺丝, 氮掺杂碳纳米纤维, 超级电容器