Adjusting the energy gap and interface effect of titania nanosheets synergistically enhances the energy storage performance of PVDF-based composites

Abstract

Polymeric dielectric materials have recently attracted much attention due to their very high potential for use as advanced energy storage capacitors. However, it is still challenging to improve the inherent low energy densities of polymer dielectrics. Herein, we demonstrate a facile and highly efficient approach, namely, adjusting the size of titania nanosheets (TNSs) as a two-dimensional (2D) filler to dramatically enhance the energy storage performance of polymer dielectrics by simultaneously adjusting the energy gap and enhancing the interface effect of the 2D nanosheets. Density functional theory (DFT) calculations indicate that small titania nanosheets (STNSs) possess a wider energy gap than large titania nanosheets (LTNSs), which could suppress the dielectric loss and leakage current of the material. Furthermore, characterization methods such as small-angle X-ray scattering are used to prove the enhanced interface effect, with the results showing that the improved dispersion and compatibility of STNSs in a polymer matrix lead to improved energy storage performance (discharge energy density U_e ∼ 11.7 J cm⁻³). Finally, the results demonstrate the efficiency of STNSs in enhancing the energy storage performance of dielectric polymers, providing a new paradigm for the application of 2D nanosheets to improve the polymer performance.