Stretching Aligned Hydrogen Bonding Network to Evoke Mechanically Robust and High-Energy-Density P(VDF-HFP) Dielectric Film Capacitors.

ABSTRACT

Polymer-based dielectric film capacitors are essential energy storage components in electronic and power systems due to their ultrahigh power density and ultra-fast charge storage/release capability. Nonetheless, their relatively low energy density does not fully meet the requirements of power electronics and pulsed power systems. Herein, a scalable composite dielectric film based on a ferroelectric polymer with edge hydroxylated boron nitride nanosheets (BNNS-OH) is fabricated via the construction of a hydrogen bonding network and stretching orientation strategy. The presence of hydroxyl groups on boron nitride aids in forming a robust hydrogen bonding network within the ferroelectric polymer, leading to a significant increase in Young's modulus and superior dielectric performance. Furthermore, the stretching process aligns the BNNS-OH and the hydrogen bonding network along the drawing direction via covalent and hydrogen bonding interaction, resulting in a remarkable tensile strength (109 MPa), breakdown strength (688 MV m-1), and energy density (28.2 J cm-3), outperforming mostrepresentative polymer-based dielectric films. In combining the advantages of a simple preparation process, extraordinary energy storage performance, and low-cost raw materials, this strategy is viable for large-scale production of polymer-based dielectric films with high mechanical and dielectric performance and opens a new path for the development of next-generation energy storage applications.