【作者】 刘伟；

【导师】 杜宁；

【作者基本信息】 浙江大学 ， 材料科学与工程， 2016， 硕士

【摘要】 近年来,便携式电子设备和电动汽车的快速发展对锂离子电池的性能提出了更高的要求,因而需要寻找高比容量、高安全性、长寿命、低成本的新型锂离子电池负极。与传统电极相比,阵列化纳米结构电极具有更好的体积膨胀包容能力、更强的电荷转移能力以及更稳定的结构等优点,是近年锂离子电池负极材料研究的热点之一。本文主要从活性材料和集流体这两个方面入手,设计并制造了几种三维阵列化纳米结构电极用作锂离子电池负极材料：在活性材料的结构设计方面,通过水热法在钛衬底上原位合成了Co3O4@SnO2@Ag三维核壳结构电极；在集流体结构的设计方面,提出了一种简单的大规模制备金属Co纳米线导电网络的方法,并在这基础上合成了Co@SnO2纳米结构电极。以上两种结构的电极均表现出了较好的电化学性能。本文的创新点在于：1.采用水热反应和射频溅射方法成功制备得到Co3O4@SnO2@Ag复合物纳米线阵列,作为锂离子电池负极材料展现了较好的电化学性能。当电流密度为200mAg-1时,Co3O4@SnO2@Ag纳米线阵列电极的首次库伦效率为89.5%,50次循环后放电容量依然保持在955.2 mAhg-1,容量保持率达到94.9%,比纯Co3O4和Co3O4@SnO2纳米线阵列均有较大提升。2.通过水热反应、氢热还原和射频溅射相结合的方法成功合成了Co@SnO2核壳结构纳米线阵列电极,该电极表现出了良好的充放电循环稳定性与大电流放电性能。在电流密度为0.5C时,Co@SnO2纳米结构电极在100次循环后放电容量维持在674.3 mAhg-1,容量保持率高达85.7%,相比Sn02平板电极的100次循环容量保持率(22.6%)有大幅提升。更多还原

【Abstract】 New anode materials for lithium-ion batteries with long cycle life and high capacity are greatly pursued to meet the increasing demands of electrical vehicles and portable electronic devices. Compared with traditional anode materials, three-dimensional nanoarray structure electrodes have received great interest, because of their significant advantages in kinetics, electronic conduction and structural stability when used as anode materials of lithium-ion batteries.In this dissertation, we propose two kinds of nanoarray structure of Co-SnO2 and Co3O4@SnO2@Ag on a Ti sheet substrate as anodes of lithium-ion batteries. Owing to the special structure, the above-mentioned nanostructured electrodes exhibit improved electrochemical performance, and our main innovative results are listed as follows:(1) We demonstrated the synthesis of Co3O4@SnO2@Ag three-dimensional nanostructure electrodes via simple hydrothermal and sputtering methods. The as-prepared electrodes show remarkably the improved initial coulombic efficiency of 89.5%, which much higher than that of the pure SnO2 nanotube array (60.3%) at the current density of 200 mA g-1. After 50 cycles, the capacity retention is about 94.9% of the first reversible capacity, which is much higher than that of CO3O4 nanowire arrays (51.7%).(2) Co@SnO2 nanowire (NW) array electrodes have been prepared by using hydrothermal, hydrogen thermal-reduction and sputtering, which exhibit high capacity and good cycling performance. After 100 cycles, the 3D nanostructured electrodes maintains at 674.3 mAhg-1 with the capacity retention of 85.7% when tested at the current density of 0.5C, which is much higher than that SnO2 planar electrodes.更多还原