石墨烯表面可控制备过渡金属硫化物及其超电容性能研究

发布时间：2018-03-06 20:30

  本文选题：超级电容器　切入点：石墨烯/金属硫化物　出处：《中国矿业大学》2017年硕士论文　论文类型：学位论文

【摘要】：超级电容器具有功率密度高、充放电时间短、循环寿命长、环保无污染等特点,有望成为下一代新型能量储存装置,是近些年来研究的热点。在整个超级电容器装置中,电极材料对超级电容器的性能起着决定性的影响。本文将具有高理论比电容的金属硫化物和具有优异循环稳定性的石墨烯进行复合,制备了Ni_3S_2/石墨烯以及三元的金属硫化物/石墨烯复合材料。研究了工艺参数对复合材料结构与电化学性能的影响,分析了复合材料结构与性能之间的关系,探讨了金属硫化物的生长机制。利用一步溶剂热法制备了Ni_3S_2和石墨烯的复合材料(NF@rGO/Ni_3S_2)。厚层片状Ni_3S_2均匀弥散地镶嵌在连续的石墨烯层中,形成多孔的三维网状结构。基于以上优异结构,该复合材料表现出良好的电化学性能:在5 mA·cm-2(0.98A·g-1)的电流密度下,复合材料的比电容可达到4048 mF·cm-2(816.8 F·g-1),远高于单纯Ni_3S_2的比电容(2335 mF·cm-2);经过6000次循环充放电,比电容保持率为93.8%。本文进一步研究了反应温度和溶剂对NF@rGO/Ni_3S_2复合材料微观结构和电化学性能的影响。当反应温度为160℃,水和乙二醇的比例为1:1时,复合材料具有最佳的结构和最优的电化学性能。以该复合材料作为正极,氮掺杂的石墨烯(N-G)作为负极,组成了水系非对称超级电容器,表现出良好的性能。0.5 A·g-1的电流密度下,其能量密度可以达到32.6 Wh·kg-1,相应的功率密度为399.8 W·kg-1。在此基础上,本文进一步优化了上述复合材料的制备方法。首先制备了三维石墨烯基底(NF@rGO),然后利用液相沉淀法在石墨烯基底表面负载了Ni_3S_2纳米颗粒。通过调整工艺参数,可以实现Ni_3S_2颗粒在石墨烯基底上的可控合成,充分发挥两种材料的最大潜能,以达到最合理的成分配比和最优异的性能。该复合材料在1 A·g-1下的比电容可以达到1140.7 F·g-1。随后,将复合硫化物(Ni_3S_2和Co_9S_8)负载到石墨烯基底上,制备了NF@rGO/Ni_3S_2/Co_9S_8复合材料。相比于NF@rGO/Ni_3S_2,后者表现出了更高的比电容和更加优异的倍率性能,这归因于石墨烯和金属硫化物之间有益的协同效应。同时,NF@rGO/Ni_3S_2/Co_9S_8//N-G非对称超级电容器展现出了优异的性能,0.5 A·g-1的电流密度下,其能量密度高达49.6 Wh·kg-1,功率密度为424.8 W·kg-1。
[Abstract]:Supercapacitors with high power density, short charge and discharge time, long cycle life, environmental protection and no pollution, are expected to become the next generation of new energy storage devices, is a hot research in recent years. Electrode materials play a decisive role in the performance of supercapacitors. In this paper, metal sulfides with high theoretical specific capacitance and graphene with excellent cyclic stability are recombined. Ni_3S_2/ graphene and ternary metal sulfide / graphene composites were prepared. The effects of process parameters on the structure and electrochemical properties of the composites were studied, and the relationship between the structure and properties of the composites was analyzed. The growth mechanism of metallic sulfides was discussed. The Ni_3S_2 and graphene composites were prepared by one-step solvothermal method. The thick lamellar Ni_3S_2 was uniformly embedded in the continuous graphene layer. Based on the above excellent structure, the composite exhibits good electrochemical properties: at the current density of 5 Ma 路cm-2(0.98A 路g -1, The specific capacitance of the composite is 4048mF 路cm-2(816.8 F 路g-1g ~ (-1), which is much higher than that of pure Ni_3S_2 (2335mF 路cm ~ (-2)). The effect of reaction temperature and solvent on the microstructure and electrochemical properties of NF@rGO/Ni_3S_2 composites was studied. When the reaction temperature was 160 鈩，

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