Preparation and characterization of Li0.30Cr0.10Ni0.60O/polyvinylidene fluoride composites with high dielectric constants

Lithium chromium nickel oxide (Li0.30Cr0.10Ni0.60O, LCNO) materials were prepared by sol-gel process and calcined at the temperature of 1000 °C for 3 h. Mechanical mixing process and hot pressing fabricated the composites between LCNO and polyvinylidene fluoride (PVDF). Effects of the amount of LCNO filler on the structure and dielectric properties of LCNO/PVDF composites were investigated. The LCNO/PVDF composites were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Furthermore, the dielectric properties of the LCNO/PVDF composites were also investigated. From TGA results, the decomposition step of LCNO/PVDF composites depends on the LCNO content and weight loss decrease with increasing LCNO contents due to the presence of LCNO in PVDF. All LCNO/PVDF composites exhibited two-phase structures of cubic rock-salt NiO structure and α-, γ- phases of PVDF. It is revealed that dielectric constant of the polymer composite increases with increasing LCNO content. This might be due to the formation of micro-capacitor network. The LCNO/PVDF composite with amount of 30 wt% showed the best properties with a high dielectric constant of 59.27 and low loss tangent of 0.31 at the frequency of 1 kHz and at room temperature. The composite gave a high dielectric constant, which was 2.82 times higher than that of pure PVDF. Therefore, the flexible high dielectric constant and low loss tangent of the composite were weakly frequency dependent, which might be suitable for capacitor applications.