Energy storage performances of polymer-based composite dielectrics containing an in-situ-grown boron nitride layer

Polymer-based energy storage materials are widely utilized in the fields of electrical and electronics due to their high-power density and excellent charge-discharge efficiency. In this study, polyetherimide (PEI) composite films with outstanding energy storage properties were prepared by growing an inorganic barrier layer of boron nitride (BN) on the surface of PEI films through the in situ chemical vapor deposition (PECVD) method. The effects of BN deposition time on the dielectric properties, leakage current density, and energy storage properties of the composite films were investigated. The results reveal that the BN inorganic barrier layer, prepared by the PECVD method, demonstrates excellent interfacial compatibility with the PEI polymer matrix and forms a densely deposited layer. The BN inorganic barrier layer effectively suppresses carrier injection at the electrode, reduces the current density inside the PEI composite film, and improves the breakdown strength of the composite film. The composite film exhibits optimal performance when BN is deposited for 20 min. At an electric field strength of 660 MV/m, the energy storage density of the composite film reaches 6.08 J/cm3, which is 1.53 J/cm3 higher than that of pure PEI, while maintaining a charge-discharge efficiency of 90.43%. The findings of this study provide valuable theoretical support for the design of polymer-based energy storage materials.