Enhancing Dielectric Energy Storage Properties of Poly(Arylene Ether Nitrile) Via Controlling the Distribution of Boron Nitride Nanosheets

Abstract Effectively regulating the filler distribution in polymer dielectric energy storage materials is crucial for enhancing their energy storage properties. In the current work, a novel strategy is proposed to improve the distribution of boron nitride nanosheets (BNNS) in poly(arylene ether nitrile) (PEN) for enhanced dielectric energy storage performances by combining phase inversion and the hot‐pressing method. PEN‐grafted BNNS (PEN@BNNS) is first prepared, carefully characterized, and then incorporated into the PEN matrix via phase inversion followed by hot‐pressing, yielding hot‐pressed PEN@BNNS/PEN (HPBP‐ x ) composite films. The SEM, TEM images, and physical pictures, together with enhanced thermal and mechanical properties of HPBP‐ x confirmed this improved distribution of BNNS in PEN. As a result, the HPBP‐9 demonstrates simultaneously enhanced dielectric constant of 4.87 and breakdown strength of 323.3 kV mm −1 , along with an excellent discharge energy density ( U d ) of 2.09 J cm −3 . Moreover, the charge–discharge efficiency is over 95% with excellent stability after 10 4 cycles. The phase inversion combined with hot‐pressing effectively improves the distribution of PEN@BNNS in PEN and significantly enhances the dielectric performances of PEN‐based dielectrics, providing new insights for developing flexible dielectric energy storage materials.