碳基纳米笼在锂离子电池中的应用研究

发布时间：2018-01-21 19:55

  本文关键词： 碳基 纳米 锂离子 电池 中的 应用 研究　出处：《南京大学》2014年硕士论文　论文类型：学位论文

【摘要】：碳材料具有导电性好、电化学／机械稳定性优异、质量轻、价格低廉及环境友好等优点,广泛用作锂离子电池的负极材料、正极材料改性剂、导电剂等。商用石墨存在比容量不够高和不耐大电流充放电等不足,具有有利于传质和电子传输的新型三维分级结构碳纳米材料日益受到重视。最近,我们课题组发展了一种制备碳基纳米笼的方法,其具有高比表面积、分级孔结构和良好导电性等特征,用作超级电容器电极材料和阴极氧还原无金属催化剂表现出优异的性能。本论文在碳基纳米笼的可控制备、锂离子电池电极材料导向的应用基础研究方面取得较好进展：(1)碳纳米笼负载LiFePO4作为锂离子电池正极材料：以苯为前驱物、原位生成的氧化镁为模板,制备出具有大比表面积(1274 m2 g-1)、高导电率(1.44 Scm-1)和分级孔结构的碳纳米笼((CNCs)。以CNCs为载体,构建出LiFePO4/CNCs复合材料,粒径约为10-25 nm的LiFePO4纳米粒子均匀分散在CNCs载体表面,其体相电导率为0.53 S cm-1,显著高于纯相LiFePO4的2.27×10-9 S cm-1。以LiFePO4/CNCs复合物作为锂离子电池的正极材料,在0.1 C下放电比容量可达163 mAh g-1,接近LiFePO4的理论比容量；在15 C和30 C高倍率下,放电比容量可达96和75 mAh g-1,15 C倍率下循环200圈后比容量为92 mAh g-1,即LiFePO4/CNCs复合物具有优异的倍率性能和循环稳定性。(2)氮掺杂碳纳米笼作为锂离子电池负极材料：以吡啶为前驱物、原位生成的氧化镁为模板制备出类似于上述CNCs结构特征的氮掺杂碳纳米笼(NCNCs)。以NCNCs作为锂离子电池负极材料,在0.1 A g-1电流密度下,NCNC700、 NCNC800和NCNC900比容量依次为710、900和700 mAh g-1,这可归因于800℃下合成的NCNCs兼具较好的导电性和较大的比表面积。在高电流密度10 A g-1和20Ag-1下,NCNC800的比容量分别达到200 mAh g-1和100 mAh g-1,且在大电流密度下循环600圈后容量无明显降低。可见,NCNCs是一种优良的锂离子电池负极材料。
[Abstract]:Carbon has the advantages of good conductivity, excellent electrochemical / mechanical stability, light weight, low price and environmental friendliness. It is widely used as anode material and modifier for lithium ion batteries. Commercial graphite has insufficient specific capacity and low resistance to charge and discharge of large current, and has been paid more and more attention to the new three-dimensional graded structure carbon nanomaterials which are beneficial to mass transfer and electron transport. Our team has developed a method for preparing carbon based nanocages, which has the characteristics of high specific surface area, graded pore structure and good electrical conductivity. As electrode material of supercapacitor and cathode oxygen reduction metal-free catalyst, this paper presents excellent performance. Good progress has been made in the application of electrode material orientation in lithium ion battery. (1) carbon nanocage supported LiFePO4 is used as cathode material for lithium ion battery: benzene is used as precursor. In situ, magnesium oxide was used as a template to produce a large specific surface area of 1274 m2 / g ~ (-1). High conductivity (1.44 Scm-1) and carbon nanocage with graded pore structure were used to fabricate LiFePO4/CNCs composites with CNCs as the carrier. LiFePO4 nanoparticles with a particle size of about 10-25 nm were uniformly dispersed on the surface of the CNCs support, and the bulk conductivity was 0.53S cm-1. It is significantly higher than that of pure phase LiFePO4 (2.27 脳 10 ~ (-9) S cm ~ (-1)). LiFePO4/CNCs complex is used as cathode material of lithium ion battery. At 0.1C, the discharge specific capacity can reach 163 mAh g-1, which is close to the theoretical specific capacity of LiFePO4. At 15 C and 30 C, the specific discharge capacity is 92 mAh g ~ (-1) at the rate of 96 and 75 mAh / g ~ (-1) ~ (15) C, and the specific capacity is 92 mAh / g ~ (-1) after cycling for 200 cycles. That is, LiFePO4/CNCs composite has excellent rate performance and cycle stability. 2) nitrogen doped carbon nanocage is used as anode material for lithium ion battery. Pyridine is used as precursor. The N-doped carbon nanocage (NCNCsN) with NCNCs as anode material for lithium-ion batteries was prepared by in-situ MgO as a template, which is similar to the above CNCs structure. At the current density of 0.1 A g ~ (-1), the specific capacities of NCNC800 and NCNC900 were 710,900 and 700 mAh / g ~ (-1), respectively. This can be attributed to the good conductivity and large specific surface area of NCNCs synthesized at 800 鈩，

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