Improved energy storage performances of solution-processable ferroelectric polymer by modulating of microscopic and mesoscopic structure

In recent years, there are many ways to improve the energy storage performance of polymer-based dielectric capacitors, especially by filling ceramic fillers into polymer matrix. However, the improvement of capacity is always limited by the structural defects due to poor interface compatibility between inorganic fillers and organic matrix. In this paper, we propose an effective method to avoid the critical issue, inorganic segments are hybrided with organic matrix in the microstructure by situ sol-gel condensation method, where zirconium-oxide (Zr–O) bonds are ionic incorporated into poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (abbreviated as PVTC) ferroelectric polymers. The effects of incorporation content on the microstructure and electrical properties have been studied. The results show that the Zr–O segments are uniformly dispersed in the polymer matrix, which can facilitate the dipole orientation and reduces dielectric loss, leading to increase of energy storage density. To further improve the performances of hybrid PVTC, the linear dielectric polyimide (PI) is introduced for constructing bilayer films with hybrid PVTC in mesoscopic structure. The optimal values of energy storage density (12.5 J/cm³) and efficiency (58%) are obtained by adjusting the volume ratios of PI layer in bilayer films. The results indicate that by synergistically modulating microscopic/mesoscopic structure is beneficial to optimize the energy storage performances of polymer-based capacitors.