锂离子电池负极材料硫化钼的制备及电化学性能研究

发布时间：2018-01-05 06:07

本文关键词：锂离子电池负极材料硫化钼的制备及电化学性能研究　出处：《华中科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：锂离子电池具有能量密度高、环境友好、循环寿命长等优点，在移动通讯等便携电子设备中得到了广泛的应用，同时锂离子电池作为最有希望的电动汽车动力来源已吸引了国内外的关注。目前锂离子电池广泛使用石墨作为负极材料，石墨负极来源丰富，电压平台平坦，库伦效率高且循环性能优异，但是比容量很低（理论容量372mAh/g），难以满足电动汽车对能量密度的要求。因此，，研究开发比容量高且循环性能好的新型负极材料具有十分重要的意义。二硫化钼作为一种典型的过渡金属硫化物，有独特的三明治结构，在诸多领域具有很好的潜在应用前景，例如润滑、催化、储氢等。层状结构有利于锂离子的嵌入脱出，没有明显的体积变化。本文对硫化钼作为锂离子电池负极材料进行了研究，采用一种简单的水热法在碱性溶液中合成硫化钼，研究了水热制备工艺对材料性能的影响及材料的形貌控制，并探索了结构和电化学性能之间的关系。采用钼酸铵和硫脲作为钼源和硫源水热合成MoS2，通过在反应物中加入NaOH可以调节硫化钼的结构从多孔的花状到致密的球状，而且所得到的硫化钼具有很好的结晶性。本文对硫化钼的水热形成机理也作了研究，认为致密的球状硫化钼是由花状硫化钼沿着纳米片的00l方向生长演变而来的。基于这一生长机理，通过改变反应中的S/Mo比或者在反应物中加入表面活性剂，可以控制硫化钼的微观结构。电化学测试结果表明，作为锂离子电池负极材料，花状硫化钼比球状硫化钼有更好的电化学性能，当电流密度为100mA/g时，花状硫化钼的可逆容量可达到900mAh/g，当电流密度高达1000mA/g时，其可逆容量仍然高达800mAh/g，是比较有潜力的锂离子电池负极材料之一。EIS表明花状硫化钼具有较低的阻抗，花状分级结构在很大程度上能够提高其电化学反应动力学特性，从而改善其电化学性能。此外，合成了一系列硫化钼复合材料，如MoS2/C和MoS2/PANI，并对其进行了初步表征。
[Abstract]:Lithium ion batteries have been widely used in portable electronic devices such as mobile communication because of their high energy density, friendly environment and long cycle life. At the same time, lithium ion battery as the most promising source of electric vehicle power has attracted the attention of domestic and foreign. At present, lithium ion battery widely use graphite as negative electrode material, graphite anode source is rich, voltage platform is flat. Coulomb has high efficiency and excellent cycle performance, but its specific capacity is very low (theoretical capacity is 372mAh/ g / g), which is difficult to meet the energy density requirements of electric vehicles. It is of great significance to study and develop new negative electrode materials with high specific capacity and good cycling performance. As a typical transition metal sulfide, molybdenum disulfide has a unique sandwich structure and has good potential applications in many fields, such as lubrication, catalysis. The layered structure is beneficial to the intercalation of lithium ion without obvious volume change. In this paper, molybdenum sulfide as anode material for lithium ion battery was studied. Molybdenum sulphide was synthesized in alkaline solution by a simple hydrothermal method. The effect of hydrothermal preparation process on the properties of the materials and the morphology control of the materials were studied. The relationship between the structure and electrochemical properties was explored. MoS _ 2 was synthesized with ammonium molybdate and thiourea as molybdenum source and sulfur source. The structure of molybdenum sulfide can be adjusted from porous flower to dense sphere by adding NaOH in the reactant. The obtained molybdenum sulfide has good crystallinity. The hydrothermal formation mechanism of molybdenum sulfide has also been studied in this paper. It is considered that the dense bulbous molybdenum sulfide evolved from the growth of the flower-shaped molybdenum sulfide along the 00l direction of the nanosheet, based on this growth mechanism. The microstructure of molybdenum sulfide can be controlled by changing the S- / Mo ratio in the reaction or adding surfactant to the reactant. The electrochemical test results show that the flower-shaped molybdenum sulfide has better electrochemical performance than the spherical molybdenum sulfide as the anode material of lithium ion battery, when the current density is 100 Ma / g. The reversible capacity of flower-shaped molybdenum sulfide can reach 900mAh/ g, and when the current density is up to 1000mAh / g, the reversible capacity is still up to 800mAh/ g. EIS shows that molybdenum flower sulfide has low impedance and flower-like classification structure can improve the electrochemical reaction kinetics to a great extent. Thus, the electrochemical performance is improved. In addition, a series of molybdenum sulfide composites, such as MoS2/C and MoS _ 2 / PANI, were synthesized and characterized.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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