Study On The Solid-liquid Composite Dielectric Materials

High energy density capacitors are the focus of current research.However,The key to prepare high energy density capacitors is to develop a kind of dielectric with high dielectric constant and high breakdown voltage.Although there are many researches on liquid dielectric and solid dielectric,there are few researches on solid-liquid composite dielectric.Considering the solid-liquid composite dielectric could increase the space polarization significantly to increase the dielectric constant,so in this study,we focused on the joint effect of the liquid DMF,PC and solid insulating film(hereafter referred to as the film)to find high energy density capacitors.In order to improve the breakdown voltage of solid-liquid composite dielectric,a proper amount of nano BaTiO3 was added to the liquid DMF and PC,and then the effect of nano BaTiO3 on the solid-liquid composite dielectric was investigated.The research mainly includes the following three parts:The capacitors were made by different materials.The dielectric constant of single component dielectric(DMF,film)and composite dielectric(DMF-film complex)were studied respectively.The result showed that the breakdown voltage of single film dielectric was high(8800 kV/m),but the dielectric constant was extremely low,therefore,the energy storage density was also extremely low(5.05 X 10-4 J/cm3)when aluminum was used as the electrode;simultaneously,pure DMF dielectric presented a low breakdown voltage and a high dielectric constant.However,the dielectric constant of DMF-film composite dielectric was significantly higher than that of single component(film or DMF).The dielectric constant of the composite dielectric could reach 1.31 × 105 at 20 Hz,and the breakdown voltage was 30 times more than that of the pure DMF dielectric.At the same time,the dielectric loss was also significantly lower than that of the pure DMF dielectric,moreover,the energy storage density was significantly higher than that of single component dielectric.Capacitors were prepared by using single PC and PC-film solid-liquid complex respectively,and the dielectric constant of the different dielectric were compared.The result showed that the breakdown voltage of single PC dielectric was 67.57 kV/m,and the energy storage density was only 1.63 X 10-4 J/cm3,while the breakdown voltage of PC-film composite dielectric was 2.93 X 103 kV/m,and the energy storage density was 3.07 J/cm3 at 20 Hz,Moreover,the dielectric constant was 5.77 X 104,all of which were significantly higher than that of the single component dielectric.Compared with DMF-film solid-liquid composite dielectric,the breakdown voltage of PC-film solid-liquid composite dielectric was 1.9 times higher,and the energy storage density was also 3.26 times higher.Nano BaTiO3 was introduced into the liquid DMF and PC,The experimental results showed that the optimal concentration of nano BaTiO3 in the modified DMF colloidal solution was 0.06 g/L.When the modified colloidal solution was combined with the film,the dielectric constant of the nano modified solid ? liquid composite dielectric was 1.39×105 at 20 Hz,and the breakdown voltage was 1733 kV/m,moreover,energy storage density was 1.85 J/cm3,which were significantly higher than that of the unmodified composite dielectric.However,the optimal concentration of nano BaTiO3 in the modified PC colloidal solution was 0.04 g/L.The dielectric constant of the nano modified solid-liquid composite dielectric was 8.34 X 104 at 20Hz.At the same time,the breakdown voltage and energy storage density were 3133 kV/m and 4.06 J/cm3 respectively,which were also significantly higher than that of the unmodified composite dielectric.