Study on the Energy Storage Perfomance of Al2O3 /PVDF Hybrid Film Based on Sol Blending Doping Strategy

With the rapid development of sensing, microelectronics, biology and nanotechnology, people have expanded their research on traditional electrically insulating dielectrics to functional dielectrics with piezoelectric effects, electrostriction, thermoelectric effects, ferroelectricity, etc., and Research on optical dielectrics such as optical fibers, electrooptic lights, and photonic crystals. At present, in high-power electronic systems, high dielectric and high energy storage polymer materials with good mechanical properties, light weight, low cost, and easy processing are widely used dielectric materials. High energy storage density dielectric materials must meet high breakdown strength and a suitably high relative dielectric constant. The addition of ceramic particles as a filler in the polymer matrix is an effective method for improving the dielectric properties and puncture resistance of composite materials. However, the uneven dispersion of the filler in the polymer matrix may cause defects resulting in a composite medium and the breakdown strength tends to decrease. Based on the above mentioned, a doping strategy of directly blending inorganic sol with organosol has been proposed for solving the bottleneck problem caused by uneven distribution of inorganic filled phase in the matrix. In this study, we had proposed a method of filling sol blends. The inorganic alumina (Al
2
O
3
) sol and Poly (vinylidene fluoride) (PVDF) sol were solution-solved by sol-gel method, and then flexible Al
2
O
3
/PVDF hybrid films were prepared by solution casting process. The microstructure and electrical properties of the polymer are systematically studied by adjusting the doping amount. The experimental results show that the Al
2
O
3
can be more uniformly dispersed in the PVDF matrix, which is conducive to reducing the dielectric loss of the matrix itself, thereby improving the overall Energy storage density. For example, when the content of Al
2
O
3
is 7.5 wt.%, the hybrid film obtains an energy density of 7.8 J/cm
³
. The results in this study indicate that the sol blending doping strategy may be expected to an effective way for improving the structural characteristics and electrical performances of the polymer-based energy storage dielectrics.