本文選題：豆莢結(jié)構(gòu)V2O3@C　切入點：VO2/Graphene　出處：《武漢科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：鋰離子電池和超級電容器是兩類重要的儲能器件。鋰離子電池具有高的能量密度和相對低的功率密度，而超級電容器具有高的功率密度、長的循環(huán)壽命和相對低的能量密度。因此，如何提高鋰離子電池的功率密度和超級電容器的能量密度是這兩類儲能器件的研究焦點。釩氧化物具有獨特的層狀結(jié)構(gòu)有利于離子的嵌入和脫出，具有較高的理論容量和較寬的電勢窗范圍，是一類理想的儲能電極材料。然而釩氧化物的導電性較差，通過與碳材料的復合提高材料的導電性能獲得高的功率密度，構(gòu)建特殊的復合結(jié)構(gòu)緩解嵌鋰時產(chǎn)生的體積膨脹提高材料的循環(huán)穩(wěn)定性。 具體研究內(nèi)容如下： 1、以五氧化二釩為釩源通過水熱法獲得尺寸均勻、長度100μm以上的超長有序V3O7H2O納米線，再通過水熱法在納米線表面包覆一層薄碳層，形成了V3O7H2O@C納米結(jié)構(gòu)，然后經(jīng)過不同溫度退火獲得豆莢結(jié)構(gòu)的V2O3@C，碳層具有極高的導電率可為電荷的快速傳輸提供便捷通道，提高材料的倍率性能；內(nèi)核豆莢結(jié)構(gòu)可以確保電解液與V2O3的有效接觸，緩解鋰離子在嵌入和脫出過程中體積發(fā)生的變化，有利于復合電極比容量和循環(huán)穩(wěn)定性的提高。超長納米線可以直接成膜作為電極材料，不需要添加沒有活性的粘結(jié)劑和額外的導電劑，是理想的柔性電極基體。 2、以五氧化二釩為釩源，取一定量的GO溶液混合均勻，，通過水熱法直接制備了VO2納米帶和石墨烯復合材料（VO2/graphene）。VO2具有獨特的層狀結(jié)構(gòu)可以提供額外的插層電容，提高材料的能量密度；VO2/graphene中的石墨烯片層能夠提供一個導電網(wǎng)絡(luò)，提高材料的倍率性能；石墨烯層包覆VO2納米帶后，能避免VO2在充放電過程中所產(chǎn)生的電化學溶解現(xiàn)象，極大的改善材料的循環(huán)穩(wěn)定性。
[Abstract]:Lithium ion batteries and supercapacitors are two important energy storage devices. Lithium ion batteries have high energy density and relatively low power density, while supercapacitors have high power density. Long cycle life and relatively low energy density. How to improve the power density of lithium-ion batteries and the energy density of supercapacitors is the research focus of these two kinds of energy storage devices. Because of its high theoretical capacity and wide range of potential window, it is an ideal material for energy storage electrode. However, vanadium oxide has poor conductivity and high power density can be obtained by improving the conductivity of the material by compounding with carbon material. A special composite structure is constructed to alleviate the volume expansion produced by lithium intercalation to improve the cyclic stability of the material. The specific contents of the study are as follows:. 1. Ultralong ordered V _ 3O _ 7H _ 2O nanowires were obtained by hydrothermal method using vanadium pentoxide as a source of vanadium. The ultralong ordered V _ 3O _ 7H _ 2O nanowires were obtained by hydrothermal method, and then a thin carbon layer was coated on the surface of the nanowires by hydrothermal method to form V _ 3O _ 7H _ 2O _ C nanostructures. Then after annealing at different temperatures, V _ 2O _ 3 @ C with pod structure was obtained. The carbon layer with extremely high conductivity can provide a convenient channel for fast charge transfer and improve the performance of the material, and the core pod structure can ensure the effective contact between electrolyte and V _ 2O _ 3. It is helpful to improve the specific capacity and cycle stability of the composite electrode by alleviating the volume change of lithium ion in the process of intercalation and stripping. The ultra-long nanowires can be used as electrode materials directly. It is an ideal flexible electrode matrix without adding inactive binder and extra conductive agent. 2. Using vanadium pentoxide as vanadium source, a certain amount of go solution was mixed uniformly, and VO2 nanobelts and graphene composites VO _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 composites were prepared directly by hydrothermal method to provide additional intercalation capacitors. The graphene layer in VO2 / graphene can provide a conductive network and improve the performance of the material, and the graphene coating can avoid the electrochemical dissolution of VO2 during charge and discharge. Greatly improve the cyclic stability of materials.
【學位授予單位】：武漢科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB332

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