Voltage-assisted 3D printing of polymer composite dielectric films with low energy loss and high energy storage density

PVDF-based polymers have garnered significant attention in the field of high-power density electrostatic capacitors due to their exceptional dielectric strength. However, their practical applications are constrained by low charge-discharge efficiency (η) and energy storage density (U_e), which stem from high ferroelectric relaxation and low breakdown strength (E_b). Here, a hydrogenated glassy polymer poly(styrene-methyl methacrylate-methylallyl alcohol) (PSMA) is designed and synthesized to be homogeneously distributed in PVDF through voltage-assisted 3D printing-hot pressing, resulting in a flexible composite film. The findings demonstrate that PSMA, rich in hydrogen bonds and high modulus strength, effectively mitigates the ferroelectric phase transition of PVDF to enhance η. Additionally, the voltage-assisted 3D printing process induces an entropy gain mechanism, facilitating the uniform distribution of the two phases and enhancing the interfacial properties for enhancing E_b. Remarkably, the study achieves prominent growth in energy storage performance, with U_e and η reaching 18.1 J/cm³ and 80 % at 525 MV/m, respectively. These remarkable results highlight the potential of 3D printing technology in enhancing the energy storage performance of PVDF-based dielectrics.