Ultrahigh energy storage performance of a polymer-based nanocomposite via interface engineering

Abstract

High-performance electrostatic capacitors are in urgent demand owing to the rapid development of higher power electronic applications. However, developing polymer-based composite films with both a high breakdown strength (E_b) and dielectric constant (ε_r) is still a huge challenge. Here, hierarchically structured SrTiO₃@SrTiO₃ nanofibers (ST@ST NFs), in which crystalline SrTiO₃ nanoparticles are embedded into the amorphous SrTiO₃ nanofibers, are incorporated into the poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-HFP)) matrix to form a multiscale internal/external interface to break the paradox of a high ε_r with decreased E_b, and that in turn gives rise to a remarkably improved energy storage capability. The percolation of the SrTiO₃–SrTiO₃ interfaces could promote interfacial polarization, resulting in a substantially increased ε_r of the polymer nanocomposites at a rather low concentration of nanofillers. More importantly, the improved E_b of 630 MV m⁻¹ is also achieved through the multiscale internal/external interface. These very favorable values give rise to an ultrahigh discharged energy density (U_d) of ∼25.26 J cm⁻³, which is 283% of the value of the pure P(VDF-HFP) film. A record enhancement ratio of U_d is achieved in this work among the previously reported results to the best of our knowledge. This approach provides a new dimension of interface engineering to adjust and improve the energy storage properties of polymer nanocomposites.