近球状钼酸镍/多壁碳纳米管复合材料的制备及其赝电容性能

Synthesis and Pseudocapacitive Behavior of Nickel Molybdate/Mutiwalled Carbon Nanotubes Composite

以硝酸镍、钼酸钠和多壁碳纳米管为原料,通过水热反应法制备了钼酸镍/多壁碳纳米管(NiMoO_4/MWCNTs)复合材料。采用扫描电子显微镜、X射线能谱和X射线衍射对材料组成和形貌进行表征。结果表明:MWCNTs很好地包覆在球状NiMoO_4外表面,且各元素均匀地分布在材料中。循环伏安和电化学阻抗实验证实MWCNTs显著增强了NiMoO_4的氧化还原信号和电荷转移动力学特性。电容测试实验进一步表明,复合材料较NiMoO_4单一材料具有更高的比电容、倍率特性及循环稳定性,且当MWCNT含量为40 mg时,所得产物(NiMoO_4/MWCNTs-40)具有最佳的电化学性能。电流密度为2 A/g时,NiMoO_4/MWCNTs-40复合材料的比电容高达1071 F/g;当电流密度增大到10 A/g时,比电容仍能保持原来的66.10%。在10 A/g的电流密度下,经过2500次循环充放电后,NiMoO_4/MWCNTs-40复合材料的比电容保持率高达95.85%,表明该材料具有出色的循环稳定性。

A novel nickel molybdate/mutiwalled carbon nanotubes（NiMoO4/MWCNTs） composite was synthesized by hydrothermal method using nickel nitrate, sodium molybdate and MWCNTs as raw materials, and the product was characterized by scanning electronic microscopy, energy dispersive spectra, and X-ray diffraction spectra. The scanning electron microscopy results showed that pseudo-spherical NiMoO4 was wrapped with MWCNTs and all elements were uniformly distributed in the material. Cyclic voltammetry and electrochemical impedance spectra revealed that the presence of MWCNTs greatly improved the redox signal and electron transfer kinetics of NiMoO4. The capacitance tests further indicated that the composite presented better specific capacitance, rate capability, and cycling stability than the single-component of NiMoO4, and with a MWCNTs content of 40 mg the composite（NiMoO4/MWCNTs-40） displayed the best electrochemical performance. At the current density of 2 A/g, the NiMoO4/MWCNTs-40 composite demonstrated a remarkable specific capacitance of 1071 F/g; while current density was increased to 10 A/g and the capacitance still remained 66.10%. Cyclic stability experiment revealed that the NiMoO4/MWCNTs-40 composite retained 95.85% of its initial specific capacitance after 2500 charge-discharge cycles at a current density of 10 A/g, exhibiting prominent electrochemical stability.