Interface Modification of Polyimide with Calcium-Based Hybrid Nanorods for Advanced Dielectrics

Abstract Polymers constitute vital dielectric media for energy-storage capacitors within contemporary electronic and electrical architectures. A persistent bottleneck in engineering high-energy-density polymer dielectrics lies in the concurrent optimization of dielectric constant and breakdown strength, two parameters traditionally bound by a trade-off relationship. In this study, one-dimensional calcium-based hybrid nanorods (denoted Ca-CP nanorods) are fabricated through a simple solution-phase strategy and introduced into polyimide (PI) matrix to synchronously boost the dielectric constant and breakdown strength of PI composites. Benefiting from bulk and interfacial effects, the composites exhibit markedly improved dielectric response, while the rigid nanorods enhance the mechanical strength of the composites and inhibit electrical breakdown channel expansion. Moreover, the positively charged surfaces of Ca-CP nanorods can efficiently capture injected and excited charge carriers, which further elevates the dielectric breakdown strength of the composite. At a Ca-CP loading of 1.5 wt %, the dielectric constant reached 5.08 at 1 kHz, and the characteristic breakdown strength reached 459 MV/m, representing increases of 69.9% and 42.5%, respectively, over pure PI. The composite achieved a maximum measured discharged energy density of 5.21 J/cm3 at 450 MV/m, outperforming most previously reported nanocomposite dielectric polymers. This study underscores the viability of exploiting organic–inorganic hybrid architectures to advance next-generation, high-performance polymer dielectrics.