Significantly Enhancing Dielectric Constant and Breakdown Strength of Linear Dielectric Polymer by Utilizing Ultralow Loadings of Nanofillers

Dielectric polymers with high electrostatic energy storage capability are the enabling technology for advanced electronics and electric power systems. However, the development of dielectric polymers is rather limited by their undesired discharged energy density (Ue) due to intrinsic low dielectric constant (K). Although large improvements of K can be achieved in dielectric polymers by introducing high filling ratios (>10 vol%) of high-K inorganic fillers, this approach has had only limited success in enhancing energy density due to the negative impact on the breakdown strength (Eb) and charge-discharge efficiency (η). Herein, we report that the incorporation of ultralow contents ( 87% at 800 MV m-1. The improvement ratios of K (~69%) and Eb (~60%) reported in this work represents the record values in the linear dielectric polymer composites with low filler contents (≦ 5 vol%). The observed dielectric enhancement is rationalized by the significant contributions of interface including enhanced polymer chain mobility and induced interfacial dipoles as revealed in the interphase dielectric model and interface simulations based on density function theory (DFT). The improved mechanical strength and raised interface charge barriers are responsible for the high Eb. This contribution paves a new avenue to scalable polymer-based dielectric materials exhibiting high energy densities and efficiencies and provides fundamental insights into the dielectric behaviors at the interfaces in polymer nanocomposites.