Bioinspired Hierarchically Structured All-Inorganic Nanocomposites with Significantly Improved Capacitive Performance

Lead-free dielectric ceramics have been the spotlight in the search for environmentally benign materials for electrostatic energy storage because of the ever-increasing environmental concerns. However, the inverse correlation between the polarization and dielectric breakdown strength is the major barrier hindering the provision of sufficient energy densities in lead-free dielectric ceramics and practical applications thereof. Herein, a rational structure design inspired by nature is demonstrated as an effective strategy to overcome these challenges. Bioinspired raspberry-like hierarchically structured all-inorganic nanocomposites have been prepared by enclosing microsized BaTiO₃-Bi(Mg_0.5Zr_0.5)O₃ (BT-BMZ) relaxor ferroelectrics using core-shell BT-BMZ@SiO₂ nanoparticles. The synergistic effects of the bioinspired hierarchical structure and insulating SiO₂ nano-coating result in significantly improved dielectric breakdown strength and sustained large polarization in the nanocomposites, as corroborated by experimental characterizations and theoretical simulations. As a result, an ultrahigh energy density of 3.41 J cm⁻³ and a high efficiency of 85.1%, together with outstanding thermal stability within a broad temperature range, have been simultaneously achieved in the hierarchically structured nanocomposites. This contribution provides a feasible and paradigmatic approach to develop high-performance dielectrics for electrostatic energy storage applications using bioinspired structure design.