钼掺杂镍钴氢氧化物电极材料的制备及其电化学性能研究

Preparation of Mo-Doped NiCo-LDH Electrode Materials and Investigation of Their Electrochemical Properties

摘要: 以六水合硝酸镍、六水合硝酸钴和二水合钼酸钠为金属源，尿素为沉淀剂，采用一步水热法制备不同钼酸钠添加量的NiCoMo-LDH电极材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱(EDS) Mapping和X射线光电子能谱(XPS)对样品的物相组成、微观形貌、元素分布及表面价态进行表征，并采用循环伏安(CV)、恒流充放电(GCD)、交流阻抗(EIS)和循环稳定性测试评价其电化学性能。结果表明，适量钼酸钠能够调控NiCo-LDH的晶体生长和层级形貌，使材料形成疏松多孔的纳米针交织结构。当钼酸钠添加量为0.3 mmol时，所制备的NiCoMo-0.3样品表现出最佳电化学性能，在1 A/g电流密度、0~0.5 V电位窗口下比电容达到1512 F/g；在5 A/g电流密度下经过3000次充放电循环后，电容保持率为73.4%。

Abstract: Using nickel nitrate hexahydrate, cobalt nitrate hexahydrate and sodium molybdate dihydrate as metal sources, and urea as a precipitant, NiCoMo-LDH electrode materials with different sodium molybdate amounts were prepared via a one-step hydrothermal method. The phase composition, microstructure, elemental distribution and surface valence states of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) mapping and X-ray photoelectron spectroscopy (XPS). Their electrochemical performance was evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycling stability tests. The results show that an appropriate amount of sodium molybdate can regulate the crystal growth and hierarchical morphology of NiCo-LDH, leading to a loose porous nanoneedle-interwoven structure. When the sodium molybdate content is 0.3 mmol, the obtained NiCoMo-0.3 sample exhibits the best electrochemical performance, achieving a specific capacitance of 1512 F/g at 1 A/g within a potential window of 0~0.5 V. After 3000 charge-discharge cycles at 5 A/g, the capacitance retention is 73.4%.