Achieving high temperature energy storage performance in PVDF through synergizing cross-linking and BNNs doping strategies

The growing demand for electrostatic capacitors in extreme conditions highlights the urgent need for polymer dielectric films with high breakdown strength ( E b ), high discharge energy density ( U e ), and outstanding high-temperature stability. Herein, a high-temperature stable capacitive composite film based on poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-CTFE)) is proposed by synergizing cross-linking and doping strategies. Specifically, P(VDF-CTFE) is engineered to form a cross-linking network and subsequently doped with surface-modified BNNs (BNNs-OH). By harnessing the synergistic effect between cross-linking and BNNs-OH doping, one can effectively restrict molecular mobility, disrupt the growth of crystalline domains, and inhibit the propagation of electrical trees and defects. This dual modification not only enhances the structural integrity of the polymer matrix but also improves its breakdown strength, high-temperature stability, and energy storage capabilities. The resultant composite film delivers a high discharge energy density up to 14.1 Jcm −3 at 25 °C and 13.59 Jcm −3 at 150 °C, validating its distinguished temperature stability over a wide temperature range. This study presents a facile strategy to develop advanced polymer dielectric films for harsh operating environments where both performance and durability are crucial.