【作者】 刘磊；

【导师】 陈蓉娜；

【作者基本信息】 燕山大学 ， 化学工艺， 2017， 硕士

【摘要】 相比于锂离子电池和镍氢电池,超级电容器作为一种能量存储装置是最具有潜力的,因为其具有高功率密度、短时间充放电和长循环寿命。超级电容器的性能特性主要取决于电极材料。因此,许多研究者致力于开发新型最佳电化学性能的电极材料。本论文选用溶剂热和化学还原法,制备了三维多级结构的Ni_xCo_9-xS₈,不同形貌的NiCo₂S₄和无定型的Ni-Co-B最佳电化学性能的电极材料。采用透射电子显微镜（TEM）、X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）、X射线光电子谱（XPS）对样品的结构、形态及组成进行了表征,以6 M KOH为电解液,采用三电极和双电极体系对材料进行电化学性能测试。具体的研究内容及结果如下:1.采用一步溶剂热法,以表面活性剂PVP为形貌剂,合成了一种新颖三维花状的NixCo9-x S8纳米片。该材料实现了高的比表面积和极好的电化学性能。电化学结果表明,在电流密度为1 A/g时的比容量为1319.76 F/g,该材料也表现出了极好的倍率性,在电流密度增大到20 A/g时,比电容仍然保持在1040.4 F/g。该电极材料在充放电循环1500圈后仍保持最大容量的90%。此外,非对称超级电容器被组装成用该材料和活性炭,该装置展现出极好的能量密度43.80 Wh/kg。2.为了探索不同形貌对NiCo₂S₄电极材料影响,采用一步溶剂热法,以乙二胺和水为混合溶剂,不同硫源做为形貌剂,制备出了不同形貌的Ni Co₂S₄。由于不同形貌的材料拥有不同的比活性位点,所以研究过程表明,以硫粉为硫源时,制备出的NiCo₂S₄ 3D花状小球表现出了最好的电化学性能。该材料在电流密度为1 A/g时,比电容值为1363.68 F/g,甚至在电流密度为20 A/g时仍达到958.32 F/g。3.通过一种温和廉价的化学还原法制备出了Ni-Co-B。并且研究了不同Ni/Co比和晶化程度对其电容性能的影响。研究结果表明,Ni/Co比为2且具有无定型结构的硼化物出示了最佳的电化学性能。这种材料展现了高的比电容,在电流密度为1 A/g时,比电容高达2226.96 F/g,甚至电流密度为20 A/g,比电容仍保持在1879.2 F/g。当以Ni-Co-B作为正极商业活性炭作为负极组装成非对称超级电容器时,该装置实现了一个极高的能量密度66.40 Wh/kg,也表现出了极好的循环稳定性,在循环5000圈后仍保持初始容量的85.76%。更多还原

【Abstract】 Supercapacitors as a sort of energy storage system are the most promising reserve force compared to Li ion battery and NI-MH batteries on the basis of their high power density,short charging-discharging time and long lifespan.The properties of supercapacitors usually depend on electrode materials.Therefore,many researchers try hard to exploit new electrode material which possess the optimal electrochemical performance.In this paper,we prepared 3D hierarchical structures Ni_xCo_9-xS₈,different morphologies NiCo₂S₄ and amorphous nickel-cobalt-borons electrode material which possess the optimal electrochemical performance.The morphology and the structure of the samples were characterized by TEM,XRD,SEM,FTIR,XPS.The electrochemical properties of materials were evaluated by using a standard three-electrode and two-electrode system in a 6.0 M KOH aqueous solution.The details and results are summarized as follows:1.A novel 3D flowerlike NixCo9-x S8 nanosheets with polyvinyl pyrrolidone as morphology agent have been synthesized via one-step solvothermal synthesis procedure.This 3D NixCo9-x S8 nanosheets achieve high specific surface area and outstanding electrochemical performance.When as for electrode materials,it demonstrates excellent specific capacitance of 1319.76 F/g at 1 A/g,and wonderful rate performance of 1040.4F/g at 20 A/g.Also,it achieves remarkable cycling stability that still retains 90% of max capacity after 1500 cycles.An asymmetric supercapacitor was assembled with Ni_xCo_9-xS₈ as a positive electrode and activated carbon（AC）as a negative electrode,it emerges high energy density 43.80 Wh/kg.2.In order to explore the affect of different morphology to NiCo₂S₄ electrode materials,we synthesized different morphology NiCo₂S₄ via one-step solvothermal synthesis procedure with ethylenediamine and water as mixed solvent and different sulfur source as morphology agent.Due to different microstructures of materials with different specific active sites,therefore,the materials of Ni Co₂S₄ 3D flower ball perform to the bestof the electrochemical performance.When as for electrode materials,it demonstrates excellent specific capacitance of 1363.68 F/g at 1 A/g,and wonderful rate performance of958.32 F/g at 20 A/g.3.Nickel-cobalt-borons are synthesized through facile and cost-effective reduction method.The effects of Ni/Co molar ratios and crystallinity on its supercapacitive performance are systematically investigated.It was found that nickel-cobalt-borons with the Ni/Co ratio being 2:1 and amorphous structure manifest the optimum specific capacitance of 2226.96 F/g at a current density of 1 A /g and still remain 1879.2 F/g at a high discharge current density of 20 A/g.An asymmetric supercapacitor device has been fabricated with nickel-cobalt-borons as the positive electrode and commercial activated carbon as the negative electrode material.The device delivers an ultrahigh energy density of 66.40 Wh/kg.This device remains at 85.76% of its initial capacitance even after 5000charge-discharge cycles.更多还原