Introduction of Nanoscale Si₃N₄ to Improve the Dielectric Thermal Stability of a Si₃N₄/P(VDF-HFP) Composite Film

In order to improve the dielectric thermal stability of polyvinylidene fluoride (PVDF)-based film, nano silicon nitride (Si₃N₄) was introduced, and hence the energy storage performance was improved. The introduction of nano Si₃N₄ fillers will induce a phase transition of P(VDF-HFP) from polar β to nonpolar α, which leads to the improved energy storage property. As such, the discharging energy density of Si₃N₄/P(VDF-HFP) composite films increased with the amount of doped Si₃N₄. After incorporating 10wt% Si₃N₄ in Si₃N₄/P(VDF-HFP) films, the discharging density increased to 1.2 J/cm³ under a relatively low electric field of 100 MV/m. Compared with a pure P(VDF-HFP) film, both the discharging energy density and thermal dielectric relaxor temperature of Si₃N₄/P(VDF-HFP) increased. The working temperature increased from 80 °C to 120 °C, which is significant for ensuring its adaptability in high-temperature energy storage areas. Thus, this result indicates that Si₃N₄ is a key filler that can improve the thermal stability of PVDF-based energy storage polymer films and may provide a reference for high-temperature capacitor materials.