Ni/Al-LDH/MCNTs原位复合材料的制备与电化学性能

以Ni（NO₃）₂·6H₂O、Al（NO₃）₃·9H₂O、尿素和MCNTs为原料，采用原位均相沉淀法制备了MCNTs含量（质量分数）分别为1%、3%和5%的Ni/Al-LDH/MCNTs复合电极活性材料。采用X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和场发射扫描电子显微镜（FESEM）表征了材料的微观结构和形貌；采用循环伏安（CV）、电化学交流阻抗（EIS）和充放电测试研究了该复合材料作为镍氢电池正极材料的电化学性能。结果表明，在Ni/Al-LDH中复合MCNTs能够提高材料的电化学活性，降低电化学反应电阻，显著改善材料的大电流充放电性能。其中MCNTs含量为3%的Ni/Al-LDH/MCNTs复合材料具有最佳的电化学性能，在200、500、1000和2000 mA·g^-1电流密度下的放电比容量分别为330、321、307和288 mA·h·g^-1，而未复合MCNTs的Ni/Al-LDH在2000 mA·g^-1电流密度下放电比容量仅为205 mA·h·g^-1。

Preparation and electrochemical performances of in-situ Ni/Al-LDH/MCNTs composites

Ni/Al-LDH/MCNTs composites with MCNTs contents of 1%, 3%, and 5% were prepared by the in-situ homogeneous precipitation method with Ni(NO₃)₃·6H₂O, Al(NO₃)₃·9H₂O, urea, and MCNTs as raw materials. The microstructure and morphology of the Ni/Al-LDH/MCNTs composites were analyzed with X-ray diffraction (XRD), Fourier transform infrared (FTIR) and field emission scanning electron microscopy (FESEM). The electrochemical performance of the Ni/Al-LDH/MCNTs composites used as cathode materials for nickel-hydrogen battery were characterized with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge tests. The results demonstrated that the introduction of MCNTs could enhance electrochemical activity, decrease electrochemical reaction resistance, and significantly improve high rate performance of Ni/Al-LDH. In particular, the Ni/Al-LDH/MCNTs composite with MCNTs content of 3% had the best electrochemical performance. For example, the specific discharge capacities of the Ni/Al-LDH/MCNTs composite with MCNTs content of 3% under current densities of 200, 500, 1000, and 2000 mA·g^-1 were 330, 321, 307, and 288 mA·h·g^-1, respectively. While for the Ni/Al-LDH without MCNTs, the specific discharge capacity was only 205 mA·h·g^-1 under the current density of 2000 mA·g^-1.