Plasticized electrospun PEO-based nanofibers as electrolyte applicable in lithium ion batteries

The development of lithium ion conducting solid polymer electrolytes (SPEs) is of current interest for use in portable devices and electric vehicles. Film casting method is a common process for the fabrication of the SPEs. In this study, all-solid-state PEO-based nanofibrous electrolytes were fabricated by using an electrospinning method. LiClO4 and ethylene carbonate (EC) were applied as lithium salt and plasticizer, respectively. The effect of EC concentration (0, 4/5% and 9% wt.) was studied on the characteristics of the as-spun electrolytes. SEM and FTIR analysis were applied to investigate the effect of EC concentration. Impedance spectroscopy was conducted at room temperature on the resulted electrospun electrolytes. The SEM results showed the reduction of average diameter of the nanofibers with the addition of EC plasticizer. The obtained result can be attributed to the enhancement of salt dissociation with the addition of EC plasticizer and so increment of solution conductivity which leads to the formation of thinner fibers. The FTIR spectra confirmed complexations between the polymer host matrix and the additives. In addition, the FTIR spectrum showed the enhancement of the fraction of free ions from 65 % to 82/62 % with the addition of 9 % wt. EC into the PEO/LiClO4 nanofibers. The highest ion conductivity of 0/16 mS.cm-1 was obtained with the addition of 9% wt. EC. The impedance of the as-spun electrolyte was 60 10 times smaller than the impedance of the film polymer electrolyte synthesized by film casting method with similar chemical composition. In fact, the highly porous structure of the nanofibers, facilitates ion path and enhances ion conduction. Therefore, the results showed that the electrospun structures can be great candidates as SPEs in lithium ion batteries.