發(fā)布時(shí)間：2018-05-18 00:01

  本文選題：鋰離子電池 + 靜電紡絲　； 參考：《江西師范大學(xué)》2014年碩士論文

【摘要】：鋰離子電池相比其他電化學(xué)裝置：具有高的能量密度、柔韌和重量輕的設(shè)計(jì)靈活，以及更長(zhǎng)的循環(huán)壽命等優(yōu)勢(shì)而受到廣泛關(guān)注�，F(xiàn)今，追求高性能和高容量負(fù)極已經(jīng)成為鋰離子電池發(fā)展的目標(biāo)之一，而硅材料因具有較高的理論比容量好低的放點(diǎn)平臺(tái)成為重點(diǎn)研究對(duì)象。但是硅為負(fù)極活性物質(zhì)時(shí)，在電化學(xué)循環(huán)過(guò)程中，存在較大的體積變化，從而造成與電極接觸性變差，導(dǎo)致容量迅速衰減。因此，為了改善硅材料作為電極活性物質(zhì)，我們從結(jié)構(gòu)設(shè)計(jì)、電極組成等方面改善鋰離子電池硅負(fù)極材料，起到了如下作用： 1）將硅納米顆粒（SiNPs）加入到聚丙烯腈（PAN）/DMF溶液中混合均勻，通過(guò)靜電紡絲，預(yù)氧化及碳化處理制備得到SiNPs負(fù)載的碳纖維膜（CNFs），然后經(jīng)過(guò)HF酸處理形成自支撐空穴狀硅碳納米纖維膜（H-Si-CNFs），直接用作鋰離子電池的負(fù)極材料。結(jié)果表明這種H-Si-CNFs電極具有良好的循環(huán)性能，當(dāng)硅納米粒子含量為10%時(shí)，， H-Si-CNFs在100mA/g充放電條件下，首次可逆容量達(dá)到了607mAh/g，經(jīng)過(guò)40次循環(huán)后的容量保留率仍有92%。 2）利用分層靜電紡技術(shù)得到了包含硅納米粒子的類隔膜電極，得到了較好的實(shí)驗(yàn)結(jié)果。800℃Si-CNFs-DCNFs復(fù)合材料具有良好的容量性能，與循環(huán)性能。以50mA/g恒流充放電，首次可逆比容量高達(dá)815.4mAh/g，首次庫(kù)倫效率為79%。經(jīng)過(guò)30次充放電后可逆比容量仍保留有690.8mA·h/g。連續(xù)的、多層的、網(wǎng)狀的碳纖維類隔膜結(jié)構(gòu)，能有效緩解充放電過(guò)程中硅體積的膨脹， 3）通過(guò)改變PAN基纖維在預(yù)氧化、碳化過(guò)程中的參數(shù)，探討了不同預(yù)氧化過(guò)程和碳化程序設(shè)置對(duì)PAN基纖維作為鋰離子電池負(fù)極材料的電化學(xué)性能的影響。通過(guò)優(yōu)化實(shí)驗(yàn)條件，得到梯度預(yù)氧化150℃（3h）→230℃（3h）→碳化600℃（1.5h）處理纖維有較高的比容量和循環(huán)穩(wěn)定性。纖維電極首次可逆比容量達(dá)到876.3mA·h/g,首次庫(kù)倫效率為65.5%，循環(huán)100次后容量保留率仍有63.2%。表明了合適的梯度預(yù)氧化溫度和時(shí)間對(duì)纖維上引入含氧官能團(tuán)，以及穩(wěn)定纖維分子結(jié)構(gòu)，起到重要作用。纖維表面適量的含氧官能團(tuán)對(duì)纖維電極容量有提高作用。碳化溫度對(duì)保持原纖樣貌有很大作用，低溫碳化能保持原纖中的“褶皺”和孔結(jié)構(gòu)，更易于Li+的嵌入/脫出。 4）進(jìn)一步對(duì)PAN基纖維梯度預(yù)氧化、碳化改性形成的最優(yōu)電化學(xué)性能的電極改性處理。其中，二次碳化改性的纖維電極首次可逆比容量高達(dá)805.8mA·h/g，經(jīng)過(guò)100次充放電測(cè)試后，仍保留有744.5mA·h/g的可逆比容量，容量保留率高達(dá)92.4%容量值和保留率值已經(jīng)遠(yuǎn)遠(yuǎn)超過(guò)石墨。
[Abstract]:Compared with other electrochemical devices, lithium-ion batteries have many advantages, such as high energy density, flexibility and light weight, flexible design, and longer cycle life. Nowadays, the pursuit of high performance and high capacity negative electrode has become one of the targets of lithium ion battery development, and silicon material has become a key research object because of its high theoretical specific capacity and low release point platform. However, when silicon is a negative active material, there is a large volume change in the electrochemical cycle, which leads to poor contact with the electrode, resulting in rapid capacity decline. Therefore, in order to improve the silicon material as electrode active material, we improve the silicon anode material of lithium ion battery from the aspects of structure design, electrode composition and so on, which plays the following role: 1) adding SiNPs into pan / DMF solution of polyacrylonitrile (pan / DMF) and mixing it evenly, and spinning it by electrospinning, Carbon fiber films supported on SiNPs were prepared by preoxidation and carbonization, and then prepared by HF acid treatment to form self-supporting cavity-like silica nanofiber films (H-Si-CNFsN), which were directly used as anode materials for lithium-ion batteries. The results show that the H-Si-CNFs electrode has good cycling performance. When the content of silicon nanoparticles is 10, the first reversible capacity of H-Si-CNFs reaches 607mAh/ g under the condition of 100mA/g charge and discharge, and the capacity retention rate is still 92 after 40 cycles. 2) the membrane like electrodes containing silicon nanoparticles were obtained by stratified electrospinning technique. The experimental results showed that the Si-CNFs-DCNFs composites at 800 鈩

本文編號(hào)：1903447