Improved Energy Storage Performance of P(VDF-TrFE-CFE) Multilayer Films by Utilizing Inorganic Functional Layers

Polymer dielectric films are the preferred materials for capacitive energy storage. However, both the discharged energy density and efficiency of ferroelectric polymers dielectrics reduced due to the ferroelectric loss and conduction loss, and so it is urgent to develop effective ways to improve the capability. In this study, inorganic functional layers (INLs), such as SiO2 and BaZrTiO3 (BZT), are grown by magnetron sputtering technology, which act as the interlayer or top/bottom layer in the P(VDF-TrFE-CFE) (PVTC) ferroelectric films. The effects of INL thickness and growth sequence on the microstructure and electrical properties have been systematically investigated. The results show that the SiO2 INL is favorable to improve the breakdown field strength, where BZT INL is beneficial to enhance the polarization of the composite films. The optimized energy storage density of 12.32 J/cm3 and an efficiency of 64.87% are obtained in the SiO2-2h/PVTC/BZT-1h/PVTC/SiO2-2h multilayer composite films. The INL forms an interfacial barrier layer at the electrode-dielectric interface, while the development of breakdown path can be inhibited at the dielectric-dielectric interface, thus reducing the leakage current and energy loss. The introduction of inorganic functional layers enables the polymer dielectric films to have an improved energy storage density and efficiency.