本文選題：鋰離子電池　切入點(diǎn)：PVP　出處：《湘潭大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：多孔碳材料因具有更加有效的充放電路徑，比較好的導(dǎo)電性和大量的鋰存儲(chǔ)的活性部位等優(yōu)點(diǎn)，將其用作鋰離子電池的負(fù)極材料具有較優(yōu)異的的電化學(xué)性能。傳統(tǒng)的制備多孔碳纖維/球的方法需要對(duì)材料進(jìn)行活化處理，其中包括復(fù)雜的物理和化學(xué)處理工藝。而靜電紡絲/靜電噴霧是一種相對(duì)而言更為簡(jiǎn)單、經(jīng)濟(jì)有效的新型制備方法。我們用經(jīng)濟(jì)環(huán)保的聚乙烯吡咯烷酮(PVP)取代聚丙烯腈原料(PAN)作為碳的前驅(qū)體，以聚甲基丙烯酸甲酯(PMMA)作為造孔劑，通過三步熱處理工藝制備多孔碳纖維/球。這此過程中，需要綜合考慮兩種原料的熱處理溫度與時(shí)間，克服PVP在熱處理過程中容易發(fā)生熱收縮導(dǎo)致很難維持纖維/球的初始形貌的困難，最終得到多孔的結(jié)構(gòu)。 本文主要以多孔碳微納纖維為研究對(duì)象，以分子量為130萬的PVP和分子量為9萬的PMMA為原材料，采用靜電紡絲法結(jié)合三步熱處理工藝，成功地制備出多孔碳微納纖維。經(jīng)過大量的熱處理對(duì)比實(shí)驗(yàn)和相關(guān)TGA、SEM測(cè)試，，最終確定了三步熱處理的溫度和時(shí)間。具體熱處理?xiàng)l件為：首先在150°C干燥24h，然后在280°C預(yù)氧化6h，最終在氮?dú)獾谋Ｗo(hù)下1000°C碳化4h。 采用X射線衍射、掃描電鏡、透射電鏡和比表面積分析儀等測(cè)試手段系統(tǒng)分析了不同PVP/PMMA質(zhì)量比對(duì)多孔碳微納纖維的形貌和微觀結(jié)構(gòu)的影響。實(shí)驗(yàn)測(cè)試結(jié)果表明當(dāng)PVP:PMMA質(zhì)量比為3:2時(shí)得到的多孔碳微納纖維其孔的尺寸屬于介孔范圍，并且它的比表面積的值最大，在沒有進(jìn)行活化的情況下可達(dá)到545.4m2·g 1。 以制備的多孔碳微納纖維作為負(fù)極材料，組裝成CR2025型扣式電池，采用電化學(xué)工作站和電池充放電測(cè)試儀系統(tǒng)研究了不同PVP/PMMA質(zhì)量比得到的多孔碳微納纖維對(duì)電化學(xué)性能的影響。結(jié)果表明：在0.1C充放電速率下，所有多孔碳微納纖維的可逆比容量比沒有加PMMA的碳微納纖維高，其中PVP/PMMA質(zhì)量比為3:2的多孔碳纖維的可逆比容量最高，50次循環(huán)之后比容量約為220mAh·g 1。本文制備的所有碳纖維樣品都有較好的循環(huán)穩(wěn)定性。 我們也嘗試采用分子量為3萬的PVP和分子量為9萬的PMMA為原材料，采用靜電噴霧法結(jié)合三步熱處理嘗試制備多孔碳球，由于碳纖維和碳球的形貌差別，相同的熱處理工藝不能成功制備出多孔碳微納球，但是通過改進(jìn)工藝條件并進(jìn)行相關(guān)的實(shí)驗(yàn)摸索，已經(jīng)得到了其熱處理的初步工藝參數(shù)。
[Abstract]:Porous carbon materials have many advantages, such as more effective charge-discharge path, better electrical conductivity and a large number of lithium-storage active sites. The anode material used for lithium ion battery has excellent electrochemical performance. The traditional method of preparing porous carbon fiber / ball requires activation of the material. These include complex physical and chemical processes, and electrostatic spinning / electrostatic spraying is a relatively simple, A new economical and effective preparation method. We used the economical and environmentally friendly polyvinylpyrrolidone (PVP) instead of polyacrylonitrile (pan) as the precursor of carbon, and the polymethyl methacrylate (PMMA) as the pore-making agent. Porous carbon fiber / ball was prepared by three-step heat treatment. In this process, the heat treatment temperature and time of two kinds of raw materials should be considered comprehensively. It is difficult to maintain the initial morphology of fiber / ball due to the thermal shrinkage of PVP during heat treatment, and the porous structure is finally obtained. In this paper, the porous carbon micro-nano fiber was used as the research object, PVP with molecular weight of 1.3 million and PMMA with molecular weight of 90,000 were used as raw materials, and the electrostatic spinning method combined with three-step heat treatment process was adopted. The porous carbon micronanofibers were successfully prepared. A large number of heat treatment contrast experiments and related TGA SEM measurements were carried out. The temperature and time of three-step heat treatment were determined as follows: drying at 150 擄C for 24 h, preoxidation at 280 擄C for 6 h and carbonization at 1000 擄C for 4 h under the protection of nitrogen. X-ray diffraction, scanning electron microscopy, The effects of different mass ratios of PVP/PMMA on the morphology and microstructure of porous carbon nanofibers were systematically analyzed by means of transmission electron microscope and surface area analyzer. The experimental results showed that the porous carbon was obtained when the mass ratio of PVP:PMMA was 3: 2. The pore size of the micro-nano fiber belongs to the mesoporous range, Moreover, its specific surface area is the largest, which can reach 545.4 m2 路g ~ (-1) without activation. The porous carbon micro-nano fiber was used as the negative electrode material to assemble the CR2025 button battery. The effect of porous carbon micro-nano fibers with different mass ratios of PVP/PMMA on electrochemical performance was studied by electrochemical workstation and battery charge-discharge tester. The results showed that: at the charge / discharge rate of 0.1C, the effect of porous carbon microfibers on electrochemical performance was studied. The reversible specific capacity of all porous carbon nanofibers is higher than that of carbon nanofibers without PMMA. The reversible specific capacity of porous carbon fiber with a mass ratio of 3: 2 is about 220 mAh 路g ~ (-1) after 50 cycles. All the carbon fiber samples prepared in this paper have good cyclic stability. We also try to use PVP with molecular weight of 30,000 and PMMA with molecular weight of 90,000 as raw materials. We also try to prepare porous carbon spheres by electrostatic spray and three-step heat treatment. Due to the different morphology of carbon fiber and carbon ball, The porous carbon microspheres could not be successfully prepared by the same heat treatment process, but the initial technological parameters of the microspheres were obtained by improving the process conditions and groping through related experiments.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM912

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