金属有机框架的合成及其衍生物储锂性能研究
发布时间:2018-12-27 10:38
【摘要】:近年来,随着化石能源的逐渐枯竭,以及由于化石燃料的使用所引起的城市雾霾等环境问题日益严重,因此开发可使清洁能源为人类大规模使用的高性能储能技术已经成为科研热点之一。锂离子电池因其环境友好、原材料易得等优势引起了人们的关注,然而由于充放电过程中的体积效应致使其比容量相对较低。锂-硫电池因较高的理论比容量、理论比能量和环境友好等优点近期获得科学界和产业界极大关注。然而硫正极材料导电性差且在充放电过程中所生成的多硫化锂易溶解在电解液中于正/负极间穿梭导致容量快速衰减。因其本论文针对以上锂-硫电池存在的关键科学问题,提出综合利用廉价的过渡金属锰氧化物负极较高的容量、对多硫化物的化学吸附特性和金属有机框架(MOF)材料较高的比表面积和孔隙率、MOF衍生物优异的导电性,分别开发了MOFs衍生包覆MnO纳米线高容量、高倍率复合负极材料和高固硫量MOF-MnO_2 NWs低温退火后产物/S多元复合正极材料。具体研究成果如下:(1)通过溶液法在室温条件下于聚乙烯吡咯烷酮(PVP)改性的水热合成MnO_2纳米线表面均匀生长尺寸约为100 nm的金属有机框架ZIF-67,扫描电子显微镜(SEM)照片显示形成了新颖的糖葫芦状ZIF-67-MnO_2结构;(2)以ZIF-67-MnO_2结构为前躯体在550 oC下氩气环境中退火后得到ZIF-67衍生碳均匀包覆的C/Co-MnO纳米线多相复合材料。由于MOF衍生碳涂层和MnO纳米线的协同效应,所得复合负极材料相比原始MnO_2纳米线具有更高的倍率和循环稳定性,而相比单纯的MOF衍生碳又具有更高的容量和更大的能量密度,在500、1000、2000和5000 mAg-1电流密度下充放电循环40圈后容量仍可分别保持在848、836、834和718 mAhg-1。(3)此外,利用300 oC氩气下ZIF-67-MnO_2 NWs退火衍生物对硫的化学吸附和物理吸附作用,获得固硫量达到60wt.%左右的ZIF-67-MnO_2 NWs退火衍生物/S的多元复合材料。作为锂-硫电池正极材料,在335和1675 mAg-1电流密度下充放电循环100圈后仍可保持612.7和365.8 mAhg-1。以上研究结果表明,本论文所提研究方案确实可行,且所开发C/Co-MnO纳米线多相复合负极材料和ZIF-67-MnO_2 NWs退火衍生物/S多元复合正极材料因其优异的储锂性能为后续开发高容量、高功率和高安全性的锂-硫电池提供重要的候选材料。
[Abstract]:In recent years, with the gradual depletion of fossil energy, as well as the use of fossil fuels caused by urban haze and other environmental problems become increasingly serious. Therefore, the development of high performance energy storage technology, which can make clean energy widely used by human beings, has become one of the hotspots in scientific research. Lithium-ion batteries have attracted much attention because of their environmental friendliness and easy availability of raw materials. However, the specific capacity of lithium-ion batteries is relatively low due to the volume effect during charging and discharging. Due to its high theoretical specific capacity, theoretical energy and environmental friendliness, lithium-sulfur batteries have recently attracted great attention from scientific and industrial circles. However, the poor conductivity of sulfur cathode materials and the easy dissolution of lithium polysulfide in the electrolyte during charge and discharge lead to rapid capacity attenuation. In view of the key scientific problems existing in the lithium-sulfur batteries mentioned above, this paper proposes to make comprehensive use of the low cost transition metal manganese oxide anode with high capacity. The chemisorption properties of polysulfide, the high specific surface area and porosity of organometallic frame (MOF) materials, and the excellent conductivity of MOF derivatives, respectively, were used to develop the high capacity of MOFs derivative coated MnO nanowires. High rate composite anode material and high sulfur fixation MOF-MnO_2 NWs low temperature annealed product / S composite cathode material. The specific research results are as follows: (1) MnO_2 nanowires were synthesized by hydrothermal synthesis of MnO_2 nanowires at room temperature by solution method at room temperature, and the surface size of MnO_2 nanowires was about 100 nm. Scanning electron microscope (SEM) (SEM) images show a novel Tomatoes on sticks shaped ZIF-67-MnO_2 structure. (2) C/Co-MnO nanowire multiphase composites with uniformly coated carbon derived from ZIF-67 were obtained by annealing in ar atmosphere at 550 oC with ZIF-67-MnO_2 structure as precursor. Because of the synergistic effect of MOF derived carbon coating and MnO nanowires, the composite anode materials have higher ratio and cycle stability than the original MnO_2 nanowires. Compared with the pure MOF derived carbon, the capacity of the charge-discharge cycle can be maintained at 848836834 mAhg-1. (3) and 718 mAhg-1. (3) after 40 cycles at the current density of 500,000,2000 and 5000 mAg-1, respectively. The chemical adsorption and physical adsorption of sulfur by ZIF-67-MnO_2 NWs annealed derivatives in argon of 300 oC were used to obtain the multicomponent composites of ZIF-67-MnO_2 NWs annealed derivatives / S with sulfur fixation of about 60 wt.%. As a cathode material for lithium-sulfur batteries, 612.7 and 365.8 mAhg-1. can still be maintained at the current density of 335 and 1675 mAg-1 after 100 cycles of charge and discharge cycles. The above results show that the research scheme proposed in this paper is feasible. The C/Co-MnO nanowire multiphase composite anode material and the ZIF-67-MnO_2 NWs annealing derivative / S multicomponent composite cathode material have been developed for the subsequent development of high capacity due to their excellent lithium storage properties. High power and high security lithium-sulfur batteries provide important candidate materials.
【学位授予单位】:南京邮电大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TB33;TM912
本文编号:2392940
[Abstract]:In recent years, with the gradual depletion of fossil energy, as well as the use of fossil fuels caused by urban haze and other environmental problems become increasingly serious. Therefore, the development of high performance energy storage technology, which can make clean energy widely used by human beings, has become one of the hotspots in scientific research. Lithium-ion batteries have attracted much attention because of their environmental friendliness and easy availability of raw materials. However, the specific capacity of lithium-ion batteries is relatively low due to the volume effect during charging and discharging. Due to its high theoretical specific capacity, theoretical energy and environmental friendliness, lithium-sulfur batteries have recently attracted great attention from scientific and industrial circles. However, the poor conductivity of sulfur cathode materials and the easy dissolution of lithium polysulfide in the electrolyte during charge and discharge lead to rapid capacity attenuation. In view of the key scientific problems existing in the lithium-sulfur batteries mentioned above, this paper proposes to make comprehensive use of the low cost transition metal manganese oxide anode with high capacity. The chemisorption properties of polysulfide, the high specific surface area and porosity of organometallic frame (MOF) materials, and the excellent conductivity of MOF derivatives, respectively, were used to develop the high capacity of MOFs derivative coated MnO nanowires. High rate composite anode material and high sulfur fixation MOF-MnO_2 NWs low temperature annealed product / S composite cathode material. The specific research results are as follows: (1) MnO_2 nanowires were synthesized by hydrothermal synthesis of MnO_2 nanowires at room temperature by solution method at room temperature, and the surface size of MnO_2 nanowires was about 100 nm. Scanning electron microscope (SEM) (SEM) images show a novel Tomatoes on sticks shaped ZIF-67-MnO_2 structure. (2) C/Co-MnO nanowire multiphase composites with uniformly coated carbon derived from ZIF-67 were obtained by annealing in ar atmosphere at 550 oC with ZIF-67-MnO_2 structure as precursor. Because of the synergistic effect of MOF derived carbon coating and MnO nanowires, the composite anode materials have higher ratio and cycle stability than the original MnO_2 nanowires. Compared with the pure MOF derived carbon, the capacity of the charge-discharge cycle can be maintained at 848836834 mAhg-1. (3) and 718 mAhg-1. (3) after 40 cycles at the current density of 500,000,2000 and 5000 mAg-1, respectively. The chemical adsorption and physical adsorption of sulfur by ZIF-67-MnO_2 NWs annealed derivatives in argon of 300 oC were used to obtain the multicomponent composites of ZIF-67-MnO_2 NWs annealed derivatives / S with sulfur fixation of about 60 wt.%. As a cathode material for lithium-sulfur batteries, 612.7 and 365.8 mAhg-1. can still be maintained at the current density of 335 and 1675 mAg-1 after 100 cycles of charge and discharge cycles. The above results show that the research scheme proposed in this paper is feasible. The C/Co-MnO nanowire multiphase composite anode material and the ZIF-67-MnO_2 NWs annealing derivative / S multicomponent composite cathode material have been developed for the subsequent development of high capacity due to their excellent lithium storage properties. High power and high security lithium-sulfur batteries provide important candidate materials.
【学位授予单位】:南京邮电大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TB33;TM912
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