The Preparation And Property Of Fluoro-polyimide Nanofibers

Lithium-ion battery has applied in many fields as high-performance battery. Separator isthe core component in Lithiun-ion battery and plays a crucial role in battery. At present,mostof the commercial separators are made of porous polyolefin with some disadvantages such aslow porosity, poor thermal property and poor wetability to battery electrolyte.In this article, fluoro-polyimide nanofibers were prepared through electrospinning andcompared them with polyimide nanofibers without fluorine. At first, two novel diamines withCF3group-2-trifluomethyl-4,4’-diaminodiphenyl ether and3-trifluomethyl-4,4’-diaminodiphenyl ether were produced,then polymerized with3,3’,4,4’-oxydiphethalicanhydride (ODPA) to prepare polyimides respectively. Polyimide made from4,4’-oxydianiline(ODA) and ODPA was also prepared for the sake of comparison.1HNMR and FT-IR resultsshowed that polyimides were all prepared successful. Three types of polyimides nanofiberswere made through electrospinning.It was showed that nanofibers had smooth surface anduniform diameter. The porosity of polyimide nanofiber mats were all between74.3%and84.7%.The thermal properties of the nanofibers were excellent that the5%weight losstemperatures were514℃,532℃and495℃in nitrogen, Tgare246℃,238℃and227℃andthere was no melting point.The results of contact angle in water and electrolyte[ethylenecarbonate/dimethyl carbonate=1/1(weight ratio)] showedthat the introduction oftrifluoromethyl can improve hydrophobic property as the contact angle increased from117oto131o.And the wettability of polyimide nanofibers in battery electrolyte improved as thecontact angle reduced from38.8o to20.2o. All the results showed that fluoro-polyimidenanofibers provide a reliable choice for the high-performance battery.