本文選題：靜電紡絲 + 鋰離子電池�。� 參考：《東華大學(xué)》2016年碩士論文

【摘要】：鋰離子電池作為一種高能電源,其具有能量密度大、使用壽命長、可快速充放電等特點,在通信、民生和國防等領(lǐng)域被廣泛的應(yīng)用。在鋰電池的結(jié)構(gòu)中,隔膜作為關(guān)鍵的內(nèi)層組件之一,其作用在于隔離電池正負極,同時為鋰離子的遷移提供通道,因此隔膜性能的優(yōu)劣直接影響到鋰離子電池的電化學(xué)性能和安全性能。商品化聚烯烴類隔膜由于較低的成本、優(yōu)異的機械性能和良好的電化學(xué)穩(wěn)定性而被廣泛的應(yīng)用在鋰電池隔膜中,但其對電解液浸潤性差,且高溫受熱時形變大,嚴重制約了鋰電池的發(fā)展與應(yīng)用。采用靜電紡絲法制備的納米纖維膜具有纖維直徑小、孔隙率高和聚合物原料選擇靈活等特點,為鋰離子電池隔膜的制備提供了新的途徑。當(dāng)前在靜電紡鋰電池隔膜領(lǐng)域已取得了一些可喜的研究成果,但鋰電池隔膜還普遍存在著力學(xué)性能較差和耐高溫性差的缺點。本文通過選用間位芳綸(PMIA)和聚氨酯(PU)作為原料,結(jié)合兩種材料各自的優(yōu)點,通過靜電紡絲技術(shù)制備出PMIA基納米纖維膜,并對其理化性能、電化學(xué)和電池性能進行研究,旨在獲得綜合性能優(yōu)異的鋰電池隔膜。首先我們選用N,N-二甲基乙酰胺(DMAc)/LiCl作為溶劑,配制出濃度為15wt%的PMIA紡絲溶液,通過靜電紡絲法制備出了PMIA納米纖維膜,并對其用于鋰電池隔膜進行了初步探討。研究結(jié)果表明:PMIA優(yōu)異的機械性能使得PMIA隔膜具有高達24.25MPa的拉伸強度;PMIA良好的耐熱性賦予了PMIA隔膜優(yōu)異的熱穩(wěn)定性;相比Celgard隔膜,PMIA隔膜高的孔隙率及出色的電解液浸潤性使其擁有較高的離子電導(dǎo)率和寬的電化學(xué)穩(wěn)定窗口;此外,在0.2C倍率下,PMIA隔膜組裝的Li/LiCoO2電池表現(xiàn)出良好的循環(huán)穩(wěn)定性。此外,我們采用溶液共混靜電紡絲技術(shù)制備出了四種不同質(zhì)量比的PMIA-PU共混納米纖維膜,并對其用于鋰電池隔膜進行了深入的研究。研究結(jié)果表明:靜電紡納米纖維膜所具有的高孔隙率、PU的引入和納米蛛網(wǎng)結(jié)構(gòu)使所制得的PMIA-PU共混隔膜具有高拉伸強度(15.79MPa)和高達1.38mS/cm的離子電導(dǎo)率;PMIA的引入賦予了共混隔膜優(yōu)異的熱穩(wěn)定性、阻燃性和出色的電解液浸潤性,共混隔膜在180℃加熱0.5h后幾乎未發(fā)生熱收縮現(xiàn)象,有利于提高鋰電池的安全性能;同時,PMIA-PU共混隔膜高達5.1V的電化學(xué)穩(wěn)定窗口能夠滿足鋰離子電池在工作電壓范圍內(nèi)正常工作的需求;此外,與商品化Celgard隔膜相比,共混隔膜組裝的Li/LiFePO4電池在0.2C倍率下循環(huán)65次后具有高的容量保持率(96.29%)以及擁有良好的倍率放電性能,使其能夠滿足鋰離子電池的應(yīng)用需求。
[Abstract]:As a kind of high energy power supply, Li-ion battery is widely used in communication, people's livelihood and national defense because of its high energy density, long service life, rapid charge and discharge and so on. In the structure of lithium battery, the diaphragm is one of the key inner components, its function is to isolate the positive and negative electrodes of the battery and to provide the channel for the migration of lithium ion. Therefore, the performance of diaphragm directly affects the electrochemical performance and safety performance of lithium ion battery. Commercial polyolefin membranes are widely used in lithium battery membranes due to their low cost, excellent mechanical properties and good electrochemical stability. The development and application of lithium battery are seriously restricted. The nanofiber membrane prepared by electrospinning has the advantages of small fiber diameter, high porosity and flexible selection of polymer raw materials, which provides a new way for the preparation of lithium ion battery membrane. At present, some gratifying research results have been obtained in the field of electrostatic spinning lithium battery diaphragm, but the disadvantages of poor mechanical properties and poor heat resistance of lithium battery diaphragm still exist in general. In this paper, PMIA based nanofiber films were prepared by electrospinning technology, and their physical and chemical properties, electrochemical and battery properties were studied by using m-aramid (PMIA) and polyurethane (PUU) as raw materials and combining the respective advantages of the two materials. The aim is to obtain lithium battery diaphragm with excellent comprehensive performance. In this paper, the PMIA nanofilament membrane was prepared by electrospinning method, and the PMIA nanofilament membrane was prepared by electrostatic spinning method, and the PMIA nanofilament membrane was prepared by electrostatic spinning method. The PMIA nanofilament membrane used in lithium battery membrane was discussed preliminarily in this paper, which was used as the solvent for the preparation of PMIA / LiCl solution with a concentration of 15 wt%. The results show that the excellent mechanical properties of the PMIA membrane make the PMIA membrane have tensile strength up to 24.25 MPA and the excellent thermal stability of the PMIA diaphragm is attributed to the excellent thermal stability of the PMIA diaphragm. Compared with Celgard membrane, PMIA membrane has high porosity and excellent electrolyte wettability, and has high ionic conductivity and wide electrochemical stability window. In addition, the Li- / LiCoO2 cell assembled with PMIA membrane exhibits good cycling stability at 0.2C ratio. In addition, four kinds of PMIA-PU nanofiber membranes with different mass ratios were prepared by solution blending electrospinning technique, and their application in lithium battery membranes was studied. The results show that the introduction of high porosity pu and the structure of nano-cobweb make the PMIA-PU blend membrane have high tensile strength (15.79MPa) and ionic conductivity up to 1.38mSpcm (PMIA). Excellent thermal stability of the mixed membrane, The flame retardancy and the excellent electrolyte wettability, the heat shrinkage phenomenon of the blend membrane almost did not occur after heating at 180 鈩，

本文編號：1996375