本文選題：鋰離子電池 + 隔膜　； 參考：《廈門大學(xué)》2014年碩士論文

【摘要】：隔膜置于鋰離子電池正負(fù)極之間,即可防止正負(fù)電極直接物理接觸,也為鋰離子提供正負(fù)電極間的傳輸通道。它的結(jié)構(gòu)嚴(yán)重影響電池界面結(jié)構(gòu)和內(nèi)阻等。電紡納米纖維膜以其高孔隙率特質(zhì)在鋰離子電池應(yīng)用中大大提高電池性能,未來(lái)將成為隔膜的主要形式之一,但其力學(xué)強(qiáng)度和安全性方而依舊存在不足,論文主要圍繞這兩個(gè)方面分別展開研究。 論文先以聚偏氟乙烯(PVDF)納米纖維膜為研究對(duì)象,研究了PVDF納米纖維膜的主要電紡工藝參數(shù)對(duì)納米纖維直徑及形貌的影響,包括溶劑比、溶液濃度、偏置電壓、工作距離和供給速率。研究結(jié)果表明,溶劑DMF和工作距離的增加使得納米纖維直徑變小,而濃度、電壓以及供液速率的增加則導(dǎo)致纖維直徑變粗。PVDF納米纖維膜具有高孔隙率、吸液率以及離子電導(dǎo)率等特性使得其放電比容量衰減小。經(jīng)100循環(huán)后,PVDF隔膜電池的放電比容量衰減僅為8.2%。 研究提高PVDF納米纖維膜力學(xué)性能的兩種方法。通過熱處理使得PVDF內(nèi)米纖維間相互粘結(jié),在不損壞電紡膜基本結(jié)構(gòu)的前提下將PVDF納米纖維膜的最大拉伸強(qiáng)度提高了25倍左右,由0.68MPa強(qiáng)化至17.43MPa。采用PET/PVDF復(fù)合膜也可提升強(qiáng)度,且具有較高力學(xué)性能,最高力學(xué)拉伸強(qiáng)度達(dá)到34.85MPa。 論文提出采用PI/PVDF/PI(聚酰亞胺)三明治結(jié)構(gòu)納米纖維膜作為可實(shí)現(xiàn)自閉功能的高安全性隔膜。研究結(jié)果顯示,電紡納米纖維膜180℃下熱縮率小于3%,表現(xiàn)出高熱穩(wěn)定性以及低熱縮率。將其應(yīng)用于鋰離子電池,經(jīng)100循環(huán)后,電池依舊保持初始放電容量的97.1%。同時(shí)中間PVDF納米纖維膜在高溫下能有效切斷電池大部分電流,提高電池安全性。
[Abstract]:If the diaphragm is placed between the positive and negative electrodes of the lithium ion battery, it can prevent the direct physical contact between the positive and negative electrodes, and also provide the transfer channel between the positive and negative electrodes for the lithium ion. Its structure seriously affects battery interface structure and internal resistance. Electrospun nanofiber membrane, with its high porosity, greatly improves the performance of the battery in the application of lithium ion battery, and will become one of the main forms of diaphragm in the future, but its mechanical strength and safety are still insufficient. The thesis mainly focuses on these two aspects. In this paper, the influence of main electrospinning process parameters on the diameter and morphology of PVDF nanofibers was studied, including solvent ratio, solution concentration and bias voltage. Working distance and supply rate. The results show that the diameter of nanofibers decreases with the increase of solvent DMF and working distance, while the increase of concentration, voltage and liquid supply rate leads to the thickening of fiber diameters. The specific discharge capacity attenuation is small due to the characteristics of liquid absorption rate and ionic conductivity. After 100 cycles, the specific discharge capacity of PVDF membrane cell is only 8.2. Two methods to improve the mechanical properties of PVDF nanofibers were studied. The maximum tensile strength of PVDF nanofiber film was increased by about 25 times without damaging the basic structure of electrospun film, which was strengthened from 0.68MPa to 17.43 MPA by heat treatment. The PET/PVDF composite film can also enhance the strength and has higher mechanical properties. The highest tensile strength of the composite film is 34.85 MPA. In this paper, Pi / PVDF / Pi (polyimide) sandwich nanofiber membrane is proposed as a high security diaphragm for self-closing function. The results show that the thermal shrinkage of electrospun nanofiber films is less than 3 at 180 鈩，

本文編號(hào)：1914951