金屬有機(jī)框架的合成及其衍生物儲(chǔ)鋰性能研究
發(fā)布時(shí)間：2018-12-27 10:38
【摘要】：近年來(lái),隨著化石能源的逐漸枯竭,以及由于化石燃料的使用所引起的城市霧霾等環(huán)境問(wèn)題日益嚴(yán)重,因此開發(fā)可使清潔能源為人類大規(guī)模使用的高性能儲(chǔ)能技術(shù)已經(jīng)成為科研熱點(diǎn)之一。鋰離子電池因其環(huán)境友好、原材料易得等優(yōu)勢(shì)引起了人們的關(guān)注,然而由于充放電過(guò)程中的體積效應(yīng)致使其比容量相對(duì)較低。鋰-硫電池因較高的理論比容量、理論比能量和環(huán)境友好等優(yōu)點(diǎn)近期獲得科學(xué)界和產(chǎn)業(yè)界極大關(guān)注。然而硫正極材料導(dǎo)電性差且在充放電過(guò)程中所生成的多硫化鋰易溶解在電解液中于正/負(fù)極間穿梭導(dǎo)致容量快速衰減。因其本論文針對(duì)以上鋰-硫電池存在的關(guān)鍵科學(xué)問(wèn)題,提出綜合利用廉價(jià)的過(guò)渡金屬錳氧化物負(fù)極較高的容量、對(duì)多硫化物的化學(xué)吸附特性和金屬有機(jī)框架(MOF)材料較高的比表面積和孔隙率、MOF衍生物優(yōu)異的導(dǎo)電性,分別開發(fā)了MOFs衍生包覆MnO納米線高容量、高倍率復(fù)合負(fù)極材料和高固硫量MOF-MnO_2 NWs低溫退火后產(chǎn)物/S多元復(fù)合正極材料。具體研究成果如下:(1)通過(guò)溶液法在室溫條件下于聚乙烯吡咯烷酮(PVP)改性的水熱合成MnO_2納米線表面均勻生長(zhǎng)尺寸約為100 nm的金屬有機(jī)框架ZIF-67,掃描電子顯微鏡(SEM)照片顯示形成了新穎的糖葫蘆狀ZIF-67-MnO_2結(jié)構(gòu);(2)以ZIF-67-MnO_2結(jié)構(gòu)為前軀體在550 oC下氬氣環(huán)境中退火后得到ZIF-67衍生碳均勻包覆的C/Co-MnO納米線多相復(fù)合材料。由于MOF衍生碳涂層和MnO納米線的協(xié)同效應(yīng),所得復(fù)合負(fù)極材料相比原始MnO_2納米線具有更高的倍率和循環(huán)穩(wěn)定性,而相比單純的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電流密度下充放電循環(huán)40圈后容量仍可分別保持在848、836、834和718 mAhg-1。(3)此外,利用300 oC氬氣下ZIF-67-MnO_2 NWs退火衍生物對(duì)硫的化學(xué)吸附和物理吸附作用,獲得固硫量達(dá)到60wt.%左右的ZIF-67-MnO_2 NWs退火衍生物/S的多元復(fù)合材料。作為鋰-硫電池正極材料,在335和1675 mAg-1電流密度下充放電循環(huán)100圈后仍可保持612.7和365.8 mAhg-1。以上研究結(jié)果表明,本論文所提研究方案確實(shí)可行,且所開發(fā)C/Co-MnO納米線多相復(fù)合負(fù)極材料和ZIF-67-MnO_2 NWs退火衍生物/S多元復(fù)合正極材料因其優(yōu)異的儲(chǔ)鋰性能為后續(xù)開發(fā)高容量、高功率和高安全性的鋰-硫電池提供重要的候選材料。
[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.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB33;TM912
本文編號(hào)：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.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB33;TM912
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