Interfacial lattice coupling engineering in all-inorganic coupled flexible films for dielectric energy storage

Hexagonal boron nitride (BN) was dispersed into the lattice of Sr2Bi4Ti5O18 (SBT) ferroelectrics to form all-inorganic flexible film capacitors. The interfacial lattice coupling in microscopic induces reconstruction of lattice and electron configuration. The electrons transfer interaction at the interfacial lattices results in the lattice stretching, thereby enhancing polyhedral dipole-dipole interactions. Meanwhile, the potential difference derived from the electron transfer provides driving force for the interfacial polarization. Above both effectively enhance the polarization without expense of breakdown strength. The interfacial lattice coupling greatly reduces the carrier generation rates under high electric field due to the ultra-high bandgap of BN, which further improves breakdown strength, thus, suppressing the inversed relationship. The recovery energy density of 119.7 J/cm3 and the efficiency of 71.2% are obtained with a consecutive mechanical bending stability. This strategy provides an alternative to break through the inversed relationship between polarization and breakdown strength for all-inorganic flexible film capacitors.