本文選題：鋰離子電池 + 五氧化二釩�。� 參考：《華南理工大學(xué)》2015年碩士論文

【摘要】：二次電池是能量儲存和轉(zhuǎn)化的重要方式。鋰離子電池因優(yōu)異的電化學(xué)性能得到廣泛的關(guān)注和應(yīng)用。正極材料和負極材料是鋰離子電池的重要組成部分,尋找容量高、循環(huán)性能優(yōu)越、成本低、環(huán)境友好的正負極材料是目前鋰離子電池領(lǐng)域的研究熱點。本論文從合成方法和結(jié)構(gòu)形貌設(shè)計入手,以釩基材料為研究重點,探討了鋰離子電池的正極材料多孔V2O5納米管、負極材料VN/石墨烯納米復(fù)合材料的合成、表征及其在電化學(xué)性能方面的研究。利用X射線衍射、掃描電鏡、透射電鏡等表征手段對制備樣品的微觀結(jié)構(gòu)和形貌進行了分析,并采用恒流充放電測試、循環(huán)伏安法測試和交流阻抗測試等技術(shù)手段研究其電化學(xué)性能。在論文第一章中,作者簡要介紹了鋰離子電池的工作原理、結(jié)構(gòu)組成等,并對常見的鋰離子電池電池正極材料和負極材料做了簡單介紹。在論文第二章中,作者簡單介紹了論文中所用到的主要實驗藥品、實驗儀器、表征手段和分析方法,闡述了電極的制備和電池的組裝,以及電池的電化學(xué)性能測試的手段和方法。在論文第三章中,我們采用低成本的釩源作前驅(qū)體,使用靜電紡絲的方法合成了多孔V2O5納米管。靜電紡絲是一種可以用來合成一維納米材料的簡單的可調(diào)節(jié)的方法。通過控制靜電紡絲的相關(guān)參數(shù),可以獲得直徑大小均勻的納米纖維。多孔V2O5納米管是多孔一維納米結(jié)構(gòu)。多孔納米結(jié)構(gòu)有利于電解液的浸潤和鋰離子的擴散距離的縮短。一維納米管具有很大的縱橫比,這可以有效避免納米材料的團聚,而且一維納米管可以沿著一維方向提供一個有效的電子通道,從而有利于電子的傳導(dǎo)。這些優(yōu)點有益于提高五氧化二釩的電化學(xué)性能。電化學(xué)性能測試結(jié)果表明,在400 oC熱處理15 min獲得的多孔五氧化二釩納米管,在2.5-4.0 V電壓范圍,放電比容量在5C、10C、20C、30C、40C、50C時分別為124.8 m Ah g-1、114.9 m Ah g-1、99.7 m Ah g-1、93.1 m Ah g-1、84.9 m Ah g-1和79.6 m Ah g-1。在50C時,經(jīng)過200次循環(huán),容量保持率是97.4%,表現(xiàn)出優(yōu)異的倍率性能和循環(huán)性能。在論文第四章中,用簡單的水熱法結(jié)合熱還原,得到VN/石墨烯納米復(fù)合材料,石墨烯的存在提高了VN的導(dǎo)電性且在一定程度上緩解了VN的聚集,VN納米顆粒的存在也阻止了石墨烯的可能堆積,兩者之間具有協(xié)同效應(yīng)。將VN/石墨烯納米復(fù)合材料作為負極材料應(yīng)用于鋰離子電池中,其表現(xiàn)出良好的倍率性能。在電壓窗口為0.01-3.0 V內(nèi),電流密度為1000 m A g-1、2000 m A g-1、3000 m A g-1時,可逆比容量為188.7 m Ah g-1、161.9 m Ah g-1和148.7 m Ah g-1。
[Abstract]:Secondary battery is an important way of energy storage and conversion.Lithium ion battery has been widely concerned and applied because of its excellent electrochemical performance.Cathode materials and anode materials are important components of lithium ion batteries. Looking for positive and negative materials with high capacity, excellent cycling performance, low cost and friendly environment is a hot research topic in the field of lithium-ion batteries.In this paper, the synthesis of porous V2O5 nanotubes and VN/ graphene nanocomposites for lithium ion batteries was studied, starting with the synthesis method and structural morphology design, and taking vanadium based materials as the focus of the research, in this paper, the synthesis of porous V2O5 nanotubes and VN/ graphene nanocomposites as anode materials for lithium ion batteries was discussed.Characterization and electrochemical properties.The microstructure and morphology of the prepared samples were analyzed by means of X-ray diffraction, scanning electron microscope and transmission electron microscope, and the constant current charge-discharge test was used.The electrochemical performance was studied by cyclic voltammetry and AC impedance measurement.In the first chapter, the author briefly introduces the working principle, structure and composition of lithium ion battery, and gives a brief introduction to the common cathode and negative materials of lithium ion battery.In the second chapter, the author briefly introduces the main experimental drugs, experimental instruments, characterization methods and analytical methods used in the paper, and describes the preparation of electrodes and the assembly of batteries.And the electrochemical performance of the battery means and methods.In chapter 3, we synthesized porous V2O5 nanotubes by electrospinning using low-cost vanadium as precursor.Electrostatic spinning is a simple and adjustable method for synthesizing one-dimensional nanomaterials.The nanofibers with uniform diameter can be obtained by controlling the parameters of electrostatic spinning.Porous V2O5 nanotubes are one-dimensional porous nanostructures.The porous nanostructure is beneficial to the infiltration of electrolyte and the shortening of the diffusion distance of lithium ion.One-dimensional nanotubes have a large aspect ratio, which can effectively avoid the agglomeration of nanomaterials, and one-dimensional nanotubes can provide an effective electron channel along the one-dimensional direction, which is conducive to the conduction of electrons.These advantages are beneficial to improve the electrochemical performance of vanadium pentoxide.The electrochemical properties of porous vanadium pentoxide nanotubes obtained by heat treatment at 400oC for 15 min were 124.8 mAh g-1114.9 mAh g-199. 7 mAh g-199. 7 mAh g-1 84.9 mAh g-1 and 79.6 mg-1Ah at the voltage range of 2.5-4.0 V, and the specific discharge capacity was 124.8 mAh g-1114.9 mAh g-1C and 79.6 mg-1 at 50C, respectively.At 50 C, after 200 cycles, the capacity retention rate is 97.4, showing excellent performance of rate and cycle.In chapter 4, VN/ graphene nanocomposites were prepared by a simple hydrothermal method combined with thermal reduction.The existence of graphene improves the electrical conductivity of VN and to some extent alleviates the existence of VN aggregating VN nanoparticles and prevents the possible accumulation of graphene. There is a synergistic effect between the two.When VN/ graphene nanocomposites were used as anode materials in lithium ion batteries, they showed good rate performance.The reversible specific capacity of 188.7 mAh g-1161.9 mAh g-1 and 148.7 mAh g-1 were obtained when the voltage window was 0.01-3.0 V and the current density was 1000 mg / g ~ (-1) 2 000 mg ~ (-1).
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ135.11;O646

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