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二氧化錫—碳基復(fù)合材料的制備及電化學(xué)儲(chǔ)鋰性能的研究

發(fā)布時(shí)間:2018-06-10 02:15

  本文選題:鋰離子電池 + 負(fù)極材料; 參考:《南昌大學(xué)》2017年碩士論文


【摘要】:鋰離子電池因其優(yōu)異的電化學(xué)性能一直受到國(guó)內(nèi)外研究人員的關(guān)注,也是新能源汽車最有潛力的儲(chǔ)能裝置。而作為鋰離子電池一部分的負(fù)極材料,其儲(chǔ)鋰性能的好壞直接影響到整個(gè)電池性能的高低,因而其一直是各國(guó)研究人員和電芯生產(chǎn)商關(guān)注的焦點(diǎn)。金屬氧化物SnO_2因具有較高的比容量、較低的毒性以及低成本等優(yōu)點(diǎn)成為石墨基負(fù)極材料最有潛力的替代材料。然而本身亦存在一些不可避免的缺點(diǎn)。圍繞其缺點(diǎn),國(guó)內(nèi)外研究人員展開了一系列的工作。本文以SnO_2為研究中心,從改變形貌以及與碳材料復(fù)合兩個(gè)方面對(duì)SnO_2進(jìn)行改性研究以提高它的電化學(xué)性能,具體內(nèi)容如下:1、以預(yù)先處理后的碳納米管為容器,通過調(diào)控表面張力,利用毛細(xì)管作用將含有錫離子的溶液引入碳納米管空腔,經(jīng)過原位氧化還原反應(yīng)生成SnO_2納米粒子并控制反應(yīng)時(shí)間合成了一系列SnO_2@OCNTs(8 h-100 h)復(fù)合材料。經(jīng)XRD、TG、TEM等理化測(cè)試表明,隨著填充時(shí)間的增加,進(jìn)入管內(nèi)的粒子就越多,此結(jié)果也與電化學(xué)測(cè)試結(jié)果相一致。當(dāng)反應(yīng)時(shí)間為100 h,SnO_2@OCNTs(100 h)表現(xiàn)優(yōu)異的儲(chǔ)鋰性能。在78 mA g-1電流密度下,首次放電比容量可達(dá)2250 mAh g-1,在0.4 A g-1下循環(huán)50次,其比容量值為804 mAh g-1,甚至在較大電流密度4 A g-1下循環(huán)200圈,材料依然保持了674 mAh g-1的放電比容量。2、以PVP/SnCl_2溶液為前驅(qū)體,采用靜電紡絲技術(shù),通過控制電壓、濃度等紡絲參數(shù)制備了不同直徑大小的PVP/SnO_2納米纖維,然經(jīng)熱處理得到SnO_2納米纖維。再將其與氧化石墨烯GO進(jìn)行物理混合,經(jīng)后續(xù)的熱處理和超聲處理制備了三種不同直徑大小的SnO_2/rGO的復(fù)合材料,并對(duì)其進(jìn)行一系列的物相和電化學(xué)表征。電化學(xué)測(cè)試結(jié)果表明,SnO_2納米纖維直徑越小,與r GO復(fù)合后,復(fù)合材料的電化學(xué)性能越優(yōu)異。其在0.4 A g-1的電流密度下進(jìn)行充放電,SnO_2/rGO循環(huán)50圈后,其比容量值可維持1987 mAh g-1。甚至在4 A g-1極大的電流密度下循環(huán)1000圈,SnO_2(2%)/rGO復(fù)合材料仍可維持649 mAh g-1,且?guī)靷愋式咏?00%。
[Abstract]:Lithium ion batteries have been paid attention by researchers at home and abroad because of their excellent electrochemical performance, and they are also the most potential energy storage devices for new energy vehicles. As a part of lithium ion battery anode material, its lithium storage performance directly affects the performance of the entire battery, so it has been the focus of attention of researchers and core manufacturers all over the world. Sno _ 2 has become the most potential substitute for graphite-based anode materials because of its high specific capacity, low toxicity and low cost. However, there are some inevitable shortcomings. Around its shortcomings, researchers at home and abroad began a series of work. In this paper, Sno _ 2 was modified to improve the electrochemical performance of SnO _ 2 by changing its morphology and compounding with carbon materials. The specific contents are as follows: 1, using pre-treated carbon nanotubes as container, and regulating surface tension. A series of SnO2 nanocomposites were synthesized by in-situ redox reaction to SnO2 nanoparticles and a series of SnO2 / OCNTsm 8h-100hs composite materials were synthesized by capillary reaction to introduce tin ions into carbon nanotubes (CNTs) cavities. The physicochemical tests such as XRDX TGX TEM show that the more particles enter the tube with the increase of filling time, the more particles enter the tube, and the results are in agreement with the electrochemical results. When the reaction time is 100 h, SnO _ 2C _ (2) C _ (CNTsN) (100 h) exhibits excellent lithium storage performance. At the current density of 78 Ma g ~ (-1), the specific capacity of the first discharge can reach 2250 mAh g ~ (-1), and the specific capacity is 804 mAh g ~ (-1) for 50 cycles at 0.4 mg ~ (-1), even when the current density is high (4 A g ~ (-1). The specific discharge capacity of 674 mAh g-1 was maintained. Using PVP / SnCl2 solution as precursor, PVP / SnCl _ 2 nanofibers with different diameters were prepared by using electrospinning technology and controlling the spinning parameters such as voltage and concentration. However, SnO _ 2 nanofibers were obtained by heat treatment. Three kinds of SnO _ 2 / rGO composites with different diameters were prepared by subsequent heat treatment and ultrasonic treatment, and a series of phase and electrochemical characterization were carried out. The results of electrochemical measurement show that the smaller the diameter of SnO-2 nanofibers, the better the electrochemical properties of the composites after composite with r go. After charging and discharging SnOs at the current density of 0.4 Ag ~ (-1) for 50 cycles, the specific capacity can be maintained at 1987 mAh g ~ (-1). Even at a maximum current density of 4Ag ~ (-1), the Sno _ 2C _ (2) / R _ (go) composite can still maintain 649 mAh g ~ (-1), and the Coulomb efficiency is close to 100 cycles.
【學(xué)位授予單位】:南昌大學(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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