Vibrational, electrical, and structural properties of PVDF-LiBOB solid polymer electrolyte with high electrochemical potential window

Polyvinylidene difluoride (PVDF)-lithium bis(oxalato)borate (LiBOB) solid polymer electrolytes (SPEs) have been prepared by solution casting. The highest ionic conductivity achieved is 3.4610(-3) S cm(-1). Electrochemical potential window of the SPEs is found around 4.7 V. Interaction between PVDF and LiBOB is studied systematically. The changes of C-C, CF2, and CH2 vibration modes with an emerging shoulder are analyzed. At higher salt content, this shoulder becomes more prominent peak at the expense of CF2 vibration mode. This suggests the possible Li+center dot center dot center dot F coordination. Deconvolution of IR spectra region from 1750 to 1850 cm(-1) has been carried out to estimate the relative percentage of free ions and contact ions. The finding is in good agreement with conductivity and XRD results. When more salt is present, the number of free ions percentage increases and the Full width at half-maximum (FWHM) of (110) plane is broadening. The Li+center dot center dot center dot F interaction breaks the folding patterns of polymer chain and enhances amorphousness domain.