本文關(guān)鍵詞： 釩酸鈉 釩酸鐵 釩酸鋰 釩酸鉀 納米線 鋰離子電池　出處：《武漢紡織大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：化石燃料的使用造成環(huán)境污染及資源日漸枯竭,鋰離子電池具有能量密度高,循環(huán)使用壽命長等優(yōu)點是解決當(dāng)今能源問題的有效途徑之一。釩氧化物納米材料是典型的層狀物,其開放結(jié)構(gòu)可以使鋰離子嵌入電極材料內(nèi)。然而,釩氧化物的缺陷是導(dǎo)電率低,在充放電時結(jié)構(gòu)不穩(wěn)定,將其與碳質(zhì)材料復(fù)合或引入金屬離子能顯著的改善上述問題。本論文圍繞釩酸鹽納米材料,采用一步溶液熱法和后續(xù)煅燒處理成功制備了釩酸鈉(Na_5V_(12)O_(32))納米線陣列,釩酸鐵(Fe_(0.12)V_2O_5)納米線陣列,釩酸鋰-還原石墨烯(Li_(0.04)V_2O_5@rGO)納米復(fù)合物,釩酸鉀(KVO)納米線陣列,并研究了其儲鋰性能。Na_5V_(12)O_(32)納米線的結(jié)構(gòu)和形貌分別采用XRD,SEM,TEM進(jìn)行表征,納米線的長度約為10.5μm。該納米線陣列具有高比表面積且直接生長在作為集流體的鈦片上,能有效的提高鋰離子遷移速率。本文對比了不同反應(yīng)時間和不同煅燒溫度下制備產(chǎn)物的電化學(xué)性能,反應(yīng)時間為1 h,煅燒溫度為250oC的樣品電化學(xué)性能最優(yōu)。其作為正極材料在電壓范圍2.0-4.0 V,電流密度為50 mA g-1時的首次放電比容量為339 mAh g-1經(jīng)過50次充放電循環(huán)后放電比容量仍為289 mAh g-1,容量保持率為85%。對制備的Fe_(0.12)V_2O_5進(jìn)行SEM,TEM表征,其納米線直徑約為30 nm,長度為幾個微米并為多孔結(jié)構(gòu)。改變反應(yīng)時間制備的樣品形貌不同,本論文提出了相應(yīng)的生長機(jī)理。Fe_(0.12)V_2O_5作為鋰離子電池正極材料時,在電壓范圍2.0-3.6 V,電流密度30 mA g-1經(jīng)過100次充放電循環(huán)后放電比容量為278 mAh g-1,容量保持率為89%。當(dāng)充放電電壓范圍擴(kuò)大為1.0-4.0 V時,在電流密度為500 mA g-1下,經(jīng)過500次充放電循環(huán)后放電比容量仍為289 mAh g-1。Li_(0.04)V_2O_5@rGO納米復(fù)合物中Li0.05V2O5納米線分散在還原石墨烯上,由于這種獨特結(jié)構(gòu),Li_(0.04)V_2O_5@rGO納米復(fù)合物具有優(yōu)良的倍率性能和循環(huán)穩(wěn)定性。Li_(0.04)V_2O_5與rGO復(fù)合前后電荷轉(zhuǎn)移電阻由178?降為81?。在電流密度為100 mA g-1時,可逆放電比容量為738 mAh g-1,經(jīng)過500次充放電循環(huán)后放電比容量仍有731 mAh g-1。生長在鈦網(wǎng)上的KVO納米線的形貌,晶型結(jié)構(gòu)和組分分別通過SEM,TEM,XRD,XPS進(jìn)行表征。該柔性電極經(jīng)過300次充放電循環(huán)后,其放電比容量仍高達(dá)270 mAh g-1。此外,該電極材料具有優(yōu)良的倍率性能,當(dāng)電流密度為960 mA g-1時,放電比容量為214mAh g-1。
[Abstract]:The use of fossil fuels causes environmental pollution and resource depletion. Lithium ion batteries have the advantages of high energy density and long cycle life. Vanadium oxide nanomaterials are typical layers. The open structure allows lithium ions to be embedded in the electrode material. However, the defect of vanadium oxide is its low conductivity and unstable structure during charge and discharge. Compounding it with carbon materials or introducing metal ions can significantly improve the above problems. In this paper, a one-step solution thermal method and a subsequent calcination process were used to prepare a sodium vanadate Na _ 5V _ T _ 12 / O _ (32) wire array around vanadate nanomaterials. The structure and morphology of the nanowires were characterized by XRD- SEMTEM. The structure and morphology of the nanowire arrays of Fex 0.12V _ 2O _ 5), lithium vanadate-reductive graphene (Li) 0.04 / V _ 2O _ 5r GOA nanocomposites, potassium vanadate / KVOO _ 2 nanowire arrays, and the lithium storage properties of the nanowires, Na _ 5V _ (12) O _ 2O _ 32) nanowires were characterized by XRD- SEMTEM, respectively. The nanowires are about 10.5 渭 m in length. The nanowire array has a high specific surface area and is grown directly on a titanium chip as a fluid collector. The electrochemical properties of the prepared products at different reaction time and calcination temperature were compared. When the reaction time is 1 h and the calcination temperature is 250oC, the electrochemical performance of the sample is optimal. The initial discharge specific capacity of the sample is 339 mAh g ~ (-1) after 50 cycles of charge and discharge when it is used as cathode material in the voltage range of 2.0-4.0 V and the current density of 50 Ma g ~ (-1). The electrical specific capacity is still 289 mAh g-1, and the capacity retention is 85. The Fe_(0.12)V_2O_5 prepared is characterized by SEM. The diameter of nanowires is about 30 nm, the length of nanowires is several microns and the structure is porous. The morphology of the samples prepared by changing the reaction time is different. In this paper, the corresponding growth mechanism. In the voltage range of 2.0-3.6 V, the specific discharge capacity of 30mAg-1 is 278mAg-1 after 100 cycles of charge and discharge, and the capacity retention is 890.When the voltage range of charge and discharge is expanded to 1.0-4.0 V, when the current density is 500mAg-1, the discharge specific capacity is 278mAg-1. After 500 charge-discharge cycles, the specific discharge capacity of the Li0.05V2O5 nanowires was still 289 mAh g-1. 1. The Li0.05V2O5 nanowires were dispersed on the reduced graphene in the V _ 2O _ 5R _ go nanocomposites. Because of this unique structure, the Litix 0.04 / V _ 2O-V _ 2O-V _ 2O _ 5C nanocomposite has excellent scaling performance and cyclic stability. Liji _ (0.04) / V _ 2O _ (5) has a charge-transfer resistance from 178 to 178 before and after the combination of the rGO and the Liji _ (0.04) V _ 2O _ (5). Down to 81? When the current density is 100mAg ~ (-1), the specific capacity of reversible discharge is 738 mAh g ~ (-1). After 500 cycles, the specific discharge capacity is still 731 mAh g ~ (-1). The morphology of KVO nanowires grown on titanium mesh is observed. The crystal structure and composition were characterized by SEMMOTEMX RDX XPS. The specific discharge capacity of the flexible electrode was still as high as 270 mAh g-1 after 300 cycles of charge and discharge. In addition, the electrode material had excellent rate performance, and when the current density was 960 Ma g ~ (-1), the specific discharge capacity of the electrode was still as high as 270 mg ~ (-1). The specific discharge capacity is 214mAh g-1.
【學(xué)位授予單位】：武漢紡織大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.1;TM912

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