Development of electrospun PVdF-PAN membrane-based polymer electrolytes for lithium batteries

Electrospun fibrous membranes of composites of polyvinylidene fluoride and polyacrylonitrile (PVdF-PAN-ESFMs) are prepared with different proportions of PAN (25, 50 and 75%, w/w). The morphology of the ESFMs is examined by field emission scanning electron microscopy (FESEM). FESEM image of PVdF-ESFM reveals that the fibers have uniform diameters and smooth surfaces. However, the fibers of PVdF-PAN-ESFMs are interconnected with large number of voids and cavities of different sizes. These voids are effectively utilized for the preparation of polymer electrolytes by loading lithium perchlorate dissolved in propylene carbonate. PVdF-PAN-ESFM with 25% PAN (designated as PVdF-PAN(25)-ESFM) could load a high amount of lithium salt with electrolyte uptake of more than 300%. PVdF-PAN(25)-ESFM electrolyte exhibits a high conductivity of 7.8 mS cm^-1 at 25 °C and electrochemically stable up to 5.1 V. Also, the addition of PAN into PVdF decreases the interfacial resistance with lithium electrode. PVdF-PAN-ESFM electrolytes have complementary advantageous characteristics of PVdF and PAN. The promising results reported here clearly indicate that polymer electrolytes based on PVdF-PAN-ESFMs are most suited for lithium batteries.