Hot Pressing of Electrospun PVdF-CTFE Membranes as Separators for Lithium Batteries: a Delicate Balance Between Mechanical Properties and Retention

A systematic investigation of the effect of hot-pressing on polyvinylidene fluoride (PVdF) - chlorotrifluoroethylene (CTFE) electrospun membranes, intended as separators and substrate for the electrolyte of lithium batteries, has been carried out by means of dynamic mechanical analysis. Absorption and desorption gravimetric measurements and infrared spectroscopy have been also performed. In particular, the mechanical properties of the membranes have been measured as a function of hot pressing temperature and pressure in the range 20 - 120 °C and 0 - 4 kbar, finding an increase of about 30 times of the tensile modulus after pressing at the highest temperature and pressure. Moreover, the conductivity of hot pressed membranes swelled by an ionic liquid measured as a function of temperature between - 60 and + 70 °C practically superimposes on that of the unpressed membrane.

本研究通过动态力学分析，系统性探究了热压处理对聚偏氟乙烯（PVdF）-三氟氯乙烯（CTFE）静电纺丝膜的影响，该类膜材被用作锂电池电解液的隔膜与基底。此外还开展了吸脱附重量法测量与红外光谱表征。具体而言，本研究测量了该膜材的力学性能随热压温度与压力的变化关系，热压温度范围为20~120℃，压力范围为0~4 kbar，结果显示在最高温压条件下热压后，膜材的拉伸模量提升约30倍。此外，经离子液体溶胀的热压膜材在-60~70℃范围内测得的电导率随温度变化曲线，与未热压膜材的电导率曲线几乎完全重合。