Enhanced energy density of PVDF-based nanocomposites via a core–shell strategy

In recent years, high energy density polymer capacitors have attracted a lot of scientific interest due to their potential applications in advanced power systems and electronic devices. Here, core–shell structured TiO 2 @SrTiO 3 @polydamine nanowires (TiO 2 @SrTiO 3 @PDA NWs) were synthesized via a combination of surface conversion reaction and in-situ polymerization method, and then incorporated into the poly(vinylidene fluoride) (PVDF) matrix. Our results showed that a small amount of TiO 2 @SrTiO 3 @PDA NWs can simultaneously enhance the breakdown strength and electric displacement of nanocomposite (NC) films, resulting in improved energy storage capability. The 5 wt% TiO 2 @SrTiO 3 @PDA NWs/PVDF NC demonstrates 1.72 times higher maximum discharge energy density compared to pristine PVDF (10.34 J/cm 3 at 198 MV/m vs. 6.01 J/cm 3 at 170 MV/m). In addition, the NC with 5 wt% TiO 2 @SrTiO 3 @PDA NWs also demonstrates an excellent charge–discharge efficiency (69% at 198 MV/m). Enhanced energy storage performance is due to hierarchical interfacial polarization among their multiple interfaces, the large aspect ratio as well as surface modification of the TiO 2 @SrTiO 3 NWs. The results of this study provide guidelines and a foundation for the preparation of the polymer NCs with an outstanding discharge energy density.