【作者】 张强；

【导师】 郑学军；

【作者基本信息】 湘潭大学 ， 材料科学与工程， 2019， 硕士

【摘要】 环境污染和能源紧缺是人类面临的首要问题。太阳能、风能等自然绿色能源的使用正在迅速增长,其进一步发展则需要智能和多功能的储能设备。因此,储能设备发展对绿色能源生产具有重要意义。超级电容器作为一种重要的电化学储能器件,具有高功率密度、充放电速度快、长循环寿命、成本低廉等优势。电极材料作为超级电容器的重要部分,直接影响其性能。因此,人们迫切需要寻找到高性能的电极材料。二硫化钒（VS₂）作为具有类石墨烯分层结构的过渡金属硫化物之一。研究表明单层VS₂具有高的比表面积和高活性位点数目,具有优异的超电储能性能。传统水热法合成的花状VS₂由于纳米片的堆叠使得比表面积和活性位点数目减少,导致其超电性能较差。本文分别制备了VS₂气凝胶和钼掺杂二硫化钒（VS₂-Mo）样品,用于提高比表面积和活性位点数目,并对它们进行了物相表征和电化学性能测试。主要内容如下。（1）首先以硫代乙酰胺、氨水、钒酸铵为前驱体,采用水热合成法制备花状VS₂样品。接着通过超声处理和冷冻干燥相结合的方法得到VS₂气凝胶。使用XRD、Raman、FESEM、TEM、XPS、EDS、对相、晶体、多孔/层状结构、形貌和元素进行了表征,并用BET测定了比表面积和孔径分布。使用电化学工作站三电极测试系统研究其电化学性能。得到结果如下:VS₂气凝胶是由少层VS₂纳米薄片相互组装而成的多孔结构,且比表面积高达21.0948 m²/g。当扫描速率为5 mV/s时,VS₂气凝胶电极的比电容高达218 F/g。当电流密度为2 A/g时,充放电1000次循环,其具有较好的容量保持率为92.78%。电化学性能的增强可归结于以下两个原因。第一是VS₂气凝胶结构具有高的比表面积可以提供较多的活性位点。第二是独特的多孔结构可以缓冲体积膨胀,提高充放电过程中的容量保持能力。（2）以硫代乙酰胺、氨水、钒酸铵、钼酸铵为前驱体,采用水热合成法制备了花状VS₂-Mo样品。使用XRD、Raman、FESEM、TEM、XPS、EDS、对相、晶体、层状结构、形貌和元素进行了表征,并用BET测定了比表面积和孔径分布。使用电化学工作站三电极测试系统研究其电化学性能。实验结果表明:花状VS₂-Mo材料的尺寸得到减小,且（001）晶面的层间距得到宽化0.586 nm。当扫描速率为5 mV/s时,VS₂-Mo电极显示的比电容高达236 F/g。当电流密度为2 A/g时,进行充放电3000次循环后,其具有较好的容量保持率为88.66%。VS₂-Mo电极优异的电化学性能可归结于以下原因。第一是VS₂-Mo样品保留了VS₂的1T相金属性的特点,仍具有较高的导电性。第二是VS₂-Mo样品在（001）晶面的层间距得到宽化,可以允许更多的离子嵌入。第三是层间距的宽化引起晶格的畸变而引入众多的缺陷,使VS₂-Mo样品的活性位点数目增加。更多还原

【Abstract】 Environmental pollution and energy shortage are the primary problems facing humanity.The use of natural green energy,such as solar and wind energy,is growing rapidly,and further development will require smart and versatile energy storage devices.Therefore,the development of energy storage equipment is of great significance to green energy production.Supercapacitors,as an important electrochemical energy storage device,have the advantages of high power density,fast charging and discharging speed,long cycle life and low cost.As an important part of supercapacitors,the electrode materials directly affect their performances.Therefore,it is urgent to find high performance electrode materials.Vanadium disulfide（VS₂）is one of the transition metal sulfides with graphene-like layered structure.The results have shown that monolayer VS2 is of high specific surface area,high number of active sites,and excellent superelectric energy storage performance.The specific surface area and the number of active sites were reduced by the stacking of nano-sheets for flower-like VS2 synthesized by traditional hydrothermal method,which results in poor super-electrical performance.In this paper,the VS2 aerogel and molybdenum-doped vanadium disulfide（VS2-Mo）samples were prepared to improve the specific surface area and the number of active sites,and their phase characterization and electrochemical properties were tested.The main contents are as follows.（1）Flower-like VS₂ materials were prepared by hydrothermal synthesis with thioacetamide,ammonia water and vanadate amine as a precursor.The VS2 aerogel materials were obtained by physical means of ultrasonic treatment and freeze drying.The phase,crystalline,layered structures,morphology,and elemental were characterized by XRD,Raman,FESEM,TEM,XPS,EDS,and the specific surface area and pore size distribution were measured by BET.The electrochemical performances were studied by using the electrochemical workstation with three-electrode test system.The results are as follows,the VS2 aerogel is a porous structure composed of several VS2 nanosheets,and has a specific surface area of up to 21.0948 m²/g.The VS₂ aerogel electrode exhibits high specific capacitance of 218 F/g at the scan rate of 5 mV/s and excellent cycle stability with 92.78%capacitance retention after 1000 consecutive charge/discharge processes at the current density of 2 A/g.The high electrochemical performances of the VS2 aerogel electrode can be attributed to the following two reasons.Firstly,the VS₂ aerogel structure with high specific surface area could provide more active sites.Secondly,the unique porous structure could buffer volume expansion to improve retention ability during charge/discharge cycles.（2）Vanadium disulfide nano-materials doped with molybdenum（VS₂-Mo）were prepared by hydrothermal synthesis with thioacetamide,ammonia,vanadate and ammonium molybdate as a precursor.The phase,crystalline,porous/layered structures,morphology,and elemental were characterized by XRD,Raman,FESEM,TEM,XPS,EDS,and the specific surface area and pore size distribution were measured by BET.The electrochemical performances were studied by using the electrochemical workstation with three-electrode test system.The results are as follows,the size of the flowered VS₂-Mo material is reduced,and the layer spacing of the（001）crystal plane is broadened up to 0.586 nm.The VS₂-Mo electrode exhibits high specific capacitance of 236 F/g at the scan rate of 5 mV/s and excellent cycle stability with 88.66%capacitance retention after 3000 consecutive charge/discharge cycles at the current density of 2 A/g.The excellent electrochemical properties of VS₂-Mo electrode can be attributed to the following three reasons.Firstly,VS₂-Mo samples still retain the metallic property of 1T phase and have high conductivity.Secondly,the interlayer spacing of VS₂-Mo samples on（001）crystal plane is widened to allow more ions embedding.Thirdly,the lattice distortion caused by the widening of interlayer spacing leads to many defects,which increases the number of active sites in VS₂-Mo samples.更多还原