High-temperature all-organic energy storage dielectric with the performance of self-adjusting electric field distribution

Abstract

As a key component of the dielectric capacitor, the dielectric material directly determines the performance of the capacitor. Poly(vinylidene fluoride) (PVDF) has received extensive attention for its large dielectric constant. However, PVDF has poor temperature resistance and cannot be used in high-temperature areas. In this work, a symmetrical sandwich structure was prepared by compounding polycarbonate (PC) and PVDF, in which PC has higher insulation and heat resistance than PVDF. It was found that as the temperature increases, the applied electric field would gradually concentrate on the PC layer, while the electric field borne by the PVDF layer gets much lower. In this way, a similarity-intelligent dielectric with the performance of self-adjusting electric field distribution was obtained, which can effectively avoid premature breakdown of PVDF under high-temperature conditions. Besides, when the PC is on the outside (CFC), it can not only increase the difficulty of carrier injection at the electrode, but also improve the heat resistance of the composite dielectric, and interface charge generated by this structure can effectively trap the carriers injected at the electrode. Finally, CFC-2 has excellent temperature stability and energy storage performance; it can withstand a breakdown strength of 500 MV m⁻¹ even at 100 °C, and its energy storage density (6.35 J cm⁻³) and charge–discharge efficiency (77.21%) are 93.52% and 91.31% of room temperature, respectively. This work effectively improves the high-temperature energy storage characteristics of PVDF and broadens its application fields. Thus, improving the high-temperature energy storage characteristics of polymer dielectrics is of great significance.