The effect of titanium dioxide nanoparticles on the structure and electrochemical properties of a PVDF/PSF composite polymer electrolyte for Li-metal battery

A composite polymer electrolyte system based on a polyvinylidene fluoride/polysulfone (PVDF/PSF) mixture with perchlorate lithium salt (LiClO4) and dispersed titanium dioxide nanoparticles in different concentrations was studied. Structural studies were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Electrochemical analysis of the composite films showed that the ionic conductivity increased with the content of titanium dioxide particles, reached a peak at about 10-15 wt. %. After this point, conductivity began to decrease. The effect of increased ion conductivity on temperature was also investigated. A maximum ionic conductivity of 1.5 x 10-5 Sm/cm was achieved at a 10 wt. % concentration of nanoparticles in the composite polymer electrolyte at room temperature. However, preheating the film up to 80°C increased the value of ionic conductivity by three times (when comparing systems with and without nanoparticles) at the same temperature. The LFP//PVDF/PSF/TiO2//Li cells exhibited excellent rate capability – 149 mAh/g at C/5 rate.