Constructing Heterogeneous-Structure TiO2@Al2O3 Nanowire Arrays in Polymer Dielectrics for Improving the Energy Storage Performance

Currently, polymer-based nanocomposites with high dielectric constant (εr) and breakdown strength (Eb) are urgently needed, which are always in a contradictory relationship. In this work, TiO2 nanowire arrays coated by Al2O3 which are synthesized by hydrothermal and ALD are introduced into the PVDF. The results show that the introduction of TiO2 nanowire arrays with high orientation polarization significantly improves the εr of PVDF. In addition, the Al2O3 can alleviate the dielectric mismatch at the interface between TiO2 and PVDF and adjust the distribution of internal electric field, leading to simultaneously improving the Eb of nanocomposites. Finally, the TiO2@Al2O3-24/PVDF nanocomposite achieves a high εr of 21 (1 kHz) and energy storage density (Ue) of 15.3 J/cm3, which is more than twice that of pure PVDF (≈ 6.69 J/cm3). This work provides an effective strategy to relieve the contradictory relationship of simultaneous high εr and high Eb of dielectrics.