高容量锂离子电池电极材料的制备与电化学性能研究

发布时间：2018-01-31 17:50

  本文关键词： 富锂正极材料 氧化镍负极材料 掺杂 空心 锂离子电池　出处：《合肥工业大学》2017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、循环寿命长、无记忆效应等诸多优点,已经成功应用于便携式电子设备中,同时正在大规模地向电动汽车和储能设备领域发展。然而目前的锂离子电池性能已经无法满足上述日益增长的需求。为了提高锂离子电池的性能,发展新型的锂离子电池正、负极材料具有重要意义。本论文在深入调研高容量富锂正极材料(LR-MNC,实际容量250 mAh g-1)和氧化镍负极材料(NiO,理论容量718 mAh g-1)的研究进展基础上,开展了基于碳酸盐共沉淀法制备富锂正极材料Li1.2Ni0.13Co0.13Mno.54O2及掺杂改性、微乳液法辅助制备一维空心结构NiO及电化学性能研究工作。主要内容如下:针对LR-MNC容量衰减、电压衰减以及倍率性能和热稳定性差的问题,对碳酸盐共沉淀法结合后续高温煅烧制备的表面多孔的球状Lii.2Ni0.13Co0.13Mn0.54O2分别进行了 Al、F单一元素掺杂和共掺杂改性的研究。A1F共掺杂结合了 Al、F单一元素掺杂的优势,可以有效缓解由层状结构向尖晶石结构的转变,因而可以抑制容量衰减和电压衰减:在0.5 C循环150次后,放电容量为217 mAh g-1且容量保持率为88.21%,平均放电电压衰减仅为0.4019 V。另一方面,A1F共掺杂可以提高离子和电子传导率,进而提升倍率性能,10C下的放电容量高达157 mAhg-1。此外,A1F共掺杂使材料的热稳定性得到改善,初始放热峰高达273℃且总产热量低至221 Jg-1。针对NiO在充放电过程中的体积膨胀问题,采用微乳液水核提供合成一维材料的模板,并利用奥氏熟化机制制备了一维空心NiO负极材料,具有均匀的形貌和优异的电化学性能。0.1 C首次放电容量为1086.2 mAh g-1,首次库伦效率为75.00%, 100次循环后放电容量保持为884.8 mAh g-1; 5 C首次放电容量为429.7 mAh g-1,经过80次循环后容量为492.5 mAh g-1; 10 C高倍率下的平均放电容量也高达363.0 mAh g-1。原反应体系放大10倍制备的NiO材料或利用回收油相制备的NiO材料均具有一维空心结构,电化学性能较好,证明了产物可以利用放大反应大量制备,并可以重复利用油相,降低成本,减少废弃有机试剂的污染。
[Abstract]:Lithium ion batteries have been successfully used in portable electronic devices because of their high energy density, long cycle life and no memory effect. At the same time, the field of electric vehicles and energy storage equipment is developing on a large scale. However, the current performance of lithium ion battery can no longer meet the increasing demand, in order to improve the performance of lithium ion battery. It is of great significance to develop new cathode materials for lithium-ion batteries. In this paper, LR-MNC with high capacity lithium-rich cathode materials has been investigated. On the basis of the actual capacity of 250 mAh g-1) and nickel oxide anode material nio, theoretical capacity of 718 mAh g-1). Lithium-rich cathode material Li1.2Ni0.13Co0.13Mno.54O2 was prepared by carbonate coprecipitation method and modified by doping. The main contents are as follows: aiming at the problems of LR-MNC capacity attenuation, voltage attenuation and poor rate performance and thermal stability. The porous spherical Lii.2Ni0.13Co0.13Mn0.54O2 prepared by carbonate coprecipitation combined with subsequent high temperature calcination was prepared respectively. Study on F single element doping and co-doping modification. A1F co-doping combined with the advantages of Alf single element doping can effectively alleviate the transition from layered structure to spinel structure. Therefore, the capacity attenuation and voltage attenuation can be suppressed: the discharge capacity is 217 mAh g ~ (-1) and the capacity retention rate is 88.21% after 150th cycle at 0. 5C. The average voltage attenuation is only 0.4019 V. on the other hand, co-doping of A1F can improve ion and electron conductivity, and then improve the rate performance. The discharge capacity at 10C is as high as 157mAhg-1.In addition, co-doping of A1F improves the thermal stability of the materials. The initial exothermic peak was as high as 273 鈩，

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