High Energy Storage Performance of PMMA Nanocomposites Utilizing Hierarchically Structured Nanowires Based on Interface Engineering

To overcome the inherent high hysteresis loss of ferroelectric polymer-based nanocomposites, non-ferroelectric linear dielectric poly(methyl methacrylate) (PMMA) is adopted as the polymer matrix for high discharge efficiency. At the same time, slender ferroelectric BaTiO3 nanowires (BT NWs) with a high dielectric constant are selected as the nanofiller for high energy density. To avoid the agglomeration of BT NWs and enhance the strength of interfaces, dopamine is used as organic coatings to tailor the interface. The BT@dopa NWs/PMMA nanocomposites exhibit excellent interface compatibility between the BT NWs and PMMA matrix and a very good microstructure uniformity. Based on this, hierarchically structured BT@SiO2@dopa NWs are designed and prepared to overcome the uneven electric field distribution at the interface, resulting from the dielectric constant mismatch. The discharged energy density (Ue) can be largely enhanced from 3.76 J/cm3 for pure PMMA films to 11.78 J/cm3 for PMMA-based nanocomposites by incorporating 5.0 wt % BT@SiO2@dopa NWs. In addition, a high discharging efficiency (η) of 91% is obtained simultaneously in the nanocomposites. Both experimental and theoretical simulations demonstrate that the double core–shell structure nanowire fillers can effectively alleviate the local field distortion, inhibit leakage current, and suppress remnant electric displacement, leading to the high Ue and η. These findings are significant in facilitating the development of high-performance film dielectric capacitor materials using PMMA-based nanocomposites toward high energy storage density.