二氧化钛复合材料的制备及储锂负极材料的性能研究

发布时间：2018-01-15 11:42

本文关键词：二氧化钛复合材料的制备及储锂负极材料的性能研究　出处：《苏州大学》2015年硕士论文　论文类型：学位论文

【摘要】：过渡金属氧化物由于其优越的电化学性能已在锂离子电池和超级电容方面引起了广泛的关注。二氧化钛是研究较早的金属氧化物负极材料,由于结构稳定、循环性能优越、价格低廉、环境友善、安全性高等特点,成为近年来的研究热点。但是Ti O2材料电子电导率低且锂离子在其内部的扩散系数较小,因而较多的研究工作旨在合成纳米尺寸的Ti O2材料,以及将Ti O2与导电碳材料、金属材料、金属氧化物材料等进行复合,提高材料的导电性。本文以碳纳米管为骨架,Ti O2作为中间层,无定形碳/二氧化钼作为外层导电层,制备了三明治结构的C/Mo O2@Ti O2@CNT复合材料,通过SEM、TEM、XRD等对材料进行物理表征,并采用了循环伏安、恒流充放电、交流阻抗等方法进行了电化学性能测试,具体内容如下:1.通过钛酸异丙酯水解产生Ti O2颗粒包覆在CNT表面,并探究了钛酸异丙酯与CNT量的配比,最终确定1 mmol的钛酸异丙酯和25 mg的CNT混合制备出了包覆均匀的Ti O2@CNT材料。以葡萄糖为碳源,将Ti O2@CNT材料置于0.1M的葡萄糖水溶液中,再经过煅烧即可制备C@Ti O2@CNT复合材料,复合材料的碳层厚度约为5 nm,含量为5.26%。三明治结构的C@Ti O2@CNT复合材料表现出了良好的电化学性能,在C/5的倍率下循环100次后容量仍保持在176 m Ah/g,Ti O2@CNT材料循环100次后的容量仅为137 m Ah/g,且复合材料的容量保持率高,库伦效率在98%左右。2.通过钼酸钠在酸性条件下的水解,在Ti O2@CNT材料表面包覆Mo O3层,再经Ar/H2将Mo O3还原成Mo O2,制备Mo O2@Ti O2@CNT复合材料。探究了Mo O2层的厚度对复合材料的结构的影响,最终确定0.5 mmol的钼酸钠与100 mg的Ti O2@CNT材料混合制备出包覆紧密、厚度均匀的Mo O2@Ti O2@CNT复合材料,Mo O2层的厚度约为10 nm,Mo O2的含量约为24.07%。Mo O2@Ti O2@CNT复合材料在C/5倍率下循环100次后容量为253 m Ah/g,且容量损失仅有9.6%,库伦效率约为98%,在30C的高倍率下进行5000次的充放电,仍能保持60 m Ah/g的容量,表现出了复合材料优越的电化学性能。3.采用恒流充放电、循环伏安等方法测试了Mo O2@Ti O2@CNT复合材料、活性炭材料水系Na2SO4电解液电容性能,并测试了AC/Mo O2@Ti O2@CNT钠离子混合超级电容器的电化学性能。以饱和甘汞电极为参比电极,Pt为对电极,复合材料为工作电极,考察了Mo O2@Ti O2@CNT复合材料在1M的Na2SO4溶液中的电容性能,首次循环时比电容119.3 F/g,循环2000次后比电容为83.5 F/g,容量保持率为70%,表现出了良好的循环稳定性。同样采用三电极体系测试了AC在1M的Na2SO4溶液中的电容性能,在相同电流密度下,Mo O2@Ti O2@CNT材料的比电容是AC的1.6~1.8倍。因而实验选取了AC:Mo O2@Ti O2@CNT质量比为2:1制作正、负极极片,组装成电容器。混合电容器在200 m A/g的电流密度下测试循环性能,首次放电电容为101F/g,经过2500次的循环之后,电容器的容量为73 F/g,容量保持率为72.3%,显示了良好的循环稳定性,同时,混合电容器还具有较好的倍率性能。
[Abstract]:Transition metal oxides due to its excellent electrochemical performance has attracted wide attention in the lithium ion battery and super capacitor. Titanium dioxide is of metal oxide anode materials earlier, due to the structural stability, superior cycle performance, low cost, environment friendly, high security features, has become the research hotspot in recent years. But the Ti O2 material the low electronic conductivity and lithium ion diffusion coefficient in the interior of the small Ti O2 material so a lot of research work aimed at synthesizing nanometer size, and the Ti and O2 conductive carbon materials, metal materials, metal oxide materials such as composite, improve the conductivity of the material. In this paper, using carbon nanotubes as framework, Ti as the middle O2 the two layer, the amorphous carbon / molybdenum oxide as the outer conductive layer, the preparation of C/Mo O2@Ti O2@CNT composite sandwich structure by SEM, TEM, XRD etc. to the physical materials Characterization and using cyclic voltammetry, galvanostatic charge discharge and AC impedance methods such as electrochemical performance test, the specific content is as follows: 1. by isopropyl titanate hydrolysis to produce Ti O2 particles coated on the surface of CNT, and to explore the isopropyl titanate and CNT CNT mixed ratio of isopropyl titanate to finalize the 1 mmol and 25 mg to prepare Ti O2@CNT material evenly coated. Using glucose as carbon source, glucose water solution Ti O2@CNT material in 0.1M, and then calcined to prepare C@Ti O2@CNT composites, carbon thickness of composite material is about 5 nm, the content of C@Ti O2@CNT composite materials a good electrochemical performance of 5.26%. sandwich structure, after 100 cycles the capacity remained at 176 m Ah/g in C/5, Ti O2@CNT after 100 cycles the capacity is only 137 m Ah/g, and the capacity of the composite to maintain a high rate of Kulun Efficiency is about 98%.2. by sodium molybdate under acidic conditions of hydrolysis, in Mo O3 Ti coating layer on the surface of O2@CNT material by Ar/H2 Mo O3 reduced to Mo O2, Mo O2@Ti O2@CNT composites were prepared. Influence of the structure of Mo O2 layer thickness of composite materials, and ultimately determine the Ti O2@CNT material mixed 0.5 mmol sodium molybdate and 100 mg prepared by coating Mo O2@Ti O2@CNT composite compact, uniform thickness, Mo thickness of the O2 layer is about 10 nm, the content of Mo O2 is about 24.07%.Mo O2@Ti O2@CNT composite at C/5 rate after 100 cycles the capacity is 253 m Ah/g, and the capacity loss only 9.6%, Kulun efficiency is about 98% and 5000 times of charge and discharge at high rate of 30C, still can maintain 60 m capacity of Ah/g showed excellent electrochemical performance of.3. composite materials by galvanostatic charge discharge, cyclic voltammetry test method Mo O2@Ti O2@CNT composite material The material, activated carbon material for aqueous Na2SO4 electrolyte capacitor properties, electrochemical properties of AC/Mo O2@Ti O2@CNT sodium ion hybrid supercapacitors were tested. The saturated calomel electrode as reference electrode, Pt composite as electrode as the working electrode, the effects of Mo O2@Ti O2@CNT composite material of capacitor performance in Na2SO4 in 1M solution for the first time, cycle specific capacitance of 119.3 F/g, after 2000 cycles, the specific capacitance is 83.5 F/g, the capacity retention rate was 70%, showing a good cycling stability. Using the same three electrode system in the AC Na2SO4 1M solution in the capacitive test, at the same current density, Mo O2@Ti ratio of O2@CNT materials the capacitance is 1.6~1.8 times of AC. Thus the experiment selected AC:Mo O2@Ti O2@CNT mass ratio of 2:1 is made, the negative pole piece, assembling capacitor. The hybrid capacitor test cycle performance at a current density of 200 m A/g, the first discharge capacity For 101F/g, after 2500 cycles, the capacity of the capacitor is 73 F/g, and the capacity holding rate is 72.3%. It shows good cycling stability. At the same time, the hybrid capacitor has good rate performance.

【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ134.11;TB33

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