Influence of finely dispersed carbon nanotubes on the performance characteristics of polymer electrolytes for lithium batteries

Electrospun membranes of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)/multiwall carbon nanotube (MWCNT) composite are prepared and loaded with lithium salts from electrolyte solution. Field emission transmission electron microscopy provides evidence for the uniform distribution of MWCNTs into the matrix of PVdF-HFP. The interconnected morphology as evident from field emission scanning electron micrograph forms the path for the lithium ion conduction. Results from electrochemical impedance spectroscopy inform that the presence of MWCNTs in PVdF-HFP matrix improves interfacial stability between lithium electrode and membrane and augment conduction path in the polymer electrolyte membrane. Further results from impedance measurement reveal the contribution of MWCNTs toward conductivity. A prototype cell is fabricated with PVdF-HFP/MWCNT as polymer electrolyte. The electrospun PVdF-HFP electrolyte membrane with 2% MWCNTs content shows an ionic conductivity of about 5.85 mS - cm(-1) at 25 degrees C. Also, PVdF-HFP/MWCNT electrolyte membrane exhibits good electrochemical and interfacial stability and can be potentially suitable as electrolyte in lithium ion secondary battery.