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High energy density polymer dielectrics play a crucial role in various pulsed energy storage and conversion systems. So far, many strategies have been demonstrated to be able to effectively improve...

Polymers with excellent dielectric properties are strongly desired for pulsed power film capacitors. However, the adverse coupling between the dielectric constant and breakdown strength greatly limits the energy storage capability of polymers. In this work, we report an easily operated method to solve this problem via sputtering the interface of bilayer polymer films with ultralow content of gold nanoparticles. Interestingly, the gold nanoparticles can effectively block the movement of charge carriers because of the Coulomb blocking effect, yielding significantly enhanced breakdown strength. Meanwhile, the gold nanoparticles can act as electrodes to form numerous equivalent microcapacitors, resulting in an obviously enhanced dielectric constant. Impressively, the polymer film with merely 0.01 vol % gold nanoparticles exhibits an obvious dielectric constant and breakdown strength, which are 129 and 131% that of the pristine polymer film, respectively. Consequently, a high energy density which is 176% of that of the pristine polymer film is achieved, and a high efficiency of 79.2% is maintained. Moreover, this process can be well combined with the production process of commercial dielectric polymer films, which is beneficial for mass production. This work offers an easily operated way to improve the dielectric capacitive energy storage properties of polymers, which could also be applicable to other materials, such as ceramics and composites.

Polymer dielectric composites are extensively used in modern electronic devices because of their extremely high power density. However, unfavorable coupling between breakdown strength and dielectric permittivity can make achieving high energy density a challenge. In this study, reduced graphene oxide @ barium titanate (RGO@BTO) hybrid nanosheets have been fabricated and utilized as fillers in the design of RGO@BTO/P(VDF-HFP) single-layer films. An increase in permittivity to 24.8@10 kHz, i.e., equivalent to 253% of the P(VDF-HFP) (∼9.8@10 kHz) matrix, has been achieved with only 1 wt % RGO@BTO nanofillers due to the formation of microcapacitors. Furthermore, the RGO@BTO/P(VDF-HFP) film is hot-pressed with a PEI film and a P(VDF-HFP) film, forming a trilayer structure. Consequently, this trilayer film displays a high breakdown strength of 478 kV/mm, a high energy density of 8.25 J/cm 3 , and a satisfactory efficiency of 64.3%. Thus, this study provides an efficient route for designing polymer composites that combine high energy density with high permittivity.