本文選題：鋰硒電池 + 正極材料��； 參考：《吉林大學(xué)》2017年碩士論文

【摘要】：硒作為電極材料具有高的電子導(dǎo)電率和理論容積密度,因而受到了科學(xué)工作者的關(guān)注。然而,鋰硒電池面臨的最大的問題是電極在工作時(shí)多硒化合物的溶解及穿梭效應(yīng),從而影響了其電化學(xué)性能。針對上述問題,本論文通過制備硒/多孔材料復(fù)合物和對電池體系中隔膜的修飾兩個(gè)方面對鋰硒電池進(jìn)行改性探究,具體內(nèi)容如下:首先,我們利用模板法制備出新型多孔碳,并且通過熔融法與硒復(fù)合形成Se/Porous carbon材料,通過多種測試方法說明了硒嵌入到Porous carbon的孔中。0.5 C(1 C=675 m Ah/g)的電流密度時(shí),1000次充放電以后放電比容量大約220m Ah/g,表現(xiàn)了良好的電化學(xué)穩(wěn)定性。隨后,我們以紙為原料,制成多孔碳作為鋰硒電池的夾層,對比不加夾層、加兩層夾層、加四層夾層,測試了電化學(xué)性能。結(jié)果表明,0.5 C的電流密度時(shí)經(jīng)過60次循環(huán),不加夾層放電比容量只有62 m Ah/g,加兩層夾層的維持在138m Ah/g,加四層夾層的能夠保持在302 m Ah/g,說明在4層paper夾層的范圍內(nèi),夾層的層數(shù)與電化學(xué)性能具有線性關(guān)系。我們還對比分析了充放電曲線,發(fā)現(xiàn)夾層層數(shù)越多,抑制穿梭效應(yīng)的效果就越好。最后,我們構(gòu)建了有TiO_2納米纖維和泡沫鎳(NFF)組成的Se-TiO_2/NFF電池體系。首先我們通過靜電紡絲技術(shù)合成了TiO_2納米纖維,再將硒和TiO_2納米纖維通過熔融過程合成得到Se-TiO_2材料,接下來把NFF(泡沫鎳)作為電池的夾層放置在電極片和隔膜中間。我們進(jìn)行了電化學(xué)測試,在0.5 C電流密度下,經(jīng)過200圈循環(huán)以后放電比容量保持在600.3 m Ah/g,并且在30 C大倍率下容量維持在321.3 m Ah/g。優(yōu)越的電化學(xué)性能主要取決于TiO_2和NFF的協(xié)同作用。同時(shí),我們在充放電期間發(fā)現(xiàn)了NFF表面發(fā)生了一個(gè)氧化還原反應(yīng)并對此進(jìn)行了研究。綜上所述,我們通過制備硒/多孔材料復(fù)合物和添加夾層修飾隔膜有效地抑制了穿梭效應(yīng),提高了電池的電子導(dǎo)電率和結(jié)構(gòu)穩(wěn)定性,優(yōu)化電池的電化學(xué)動力學(xué)性質(zhì),從而提高其倍率性能、放電比容量以及循環(huán)性能。本文為鋰硒電池的研究提供了理論和實(shí)驗(yàn)依據(jù)。
[Abstract]:Selenium as an electrode material has high electron conductivity and theoretical volume density, so it has attracted the attention of scientists. However, the biggest problem facing lithium selenium battery is the dissolving and shuttling effect of multi-selenium compounds in the electrode, which affects its electrochemical performance. In order to solve the above problems, this paper studied the modification of lithium selenium battery by preparing selenium / porous composite and modifying the membrane in the battery system. The specific contents are as follows: firstly, we prepared new porous carbon by template method. In addition, Se- / Porous carbon materials were formed by melting method combined with selenium. A variety of measurement methods show that the specific discharge capacity of selenium embedded in the pore of Porous carbon is about 220 m / g at the current density of 0.5C (1 C + 675 m Ah/g) after 1 000 charges and discharges, showing good electrochemical stability. Then we made porous carbon as the interlayer of lithium selenium battery with paper as raw material. The electrochemical performance was tested by adding two layers and four layers respectively. The results show that when the current density is 0.5 C, the discharge specific capacity is only 62 m / g without interlayer, with two layers at 138 m / g, and four layers with four layers can be kept at 302m / g, indicating that the range of four layers of paper interlayer is within the range of 4 layers. There is a linear relationship between the number of layers and electrochemical performance. We also compare the charge-discharge curves and find that the more intercalation layers, the better the suppression effect of shuttle effect. Finally, we constructed a Se-TiOS _ 2 / NFF battery system consisting of TiO-2 nanofibers and nickel foam (NFF). First, we synthesized TiO2 nanofibers by electrospinning technology, then synthesized Se-TiO2 nanofibers by melting process from selenium and TiO2 nanofibers, and then placed NFF (nickel foam) as the interlayer of the battery between the electrode sheet and the diaphragm. The electrochemical measurements show that the specific discharge capacity is kept at 600.3 m 路h / g at 0.5C current density and 321.3 m / g at 30 C at large rate after 200 cycles. Superior electrochemical performance mainly depends on the synergistic effect of TiO _ 2 and NFF. At the same time, a redox reaction on the surface of NFF was found and studied during charge and discharge. To sum up, we effectively inhibit the shuttle effect by preparing selenium / porous composite and adding interlayer modified diaphragm, improve the electronic conductivity and structural stability of the battery, and optimize the electrochemical dynamic properties of the battery. In order to improve its rate performance, discharge specific capacity and cycle performance. This paper provides theoretical and experimental basis for the study of lithium-selenium battery.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM912

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本文編號：2055008