Simultaneous enhancement of polarization and breakdown strength in lead-free BaTiO3-based ceramics

Lead-free dielectric ceramic capacitors have garnered extensive attention owing to their excellent dielectric and energy storage characteristics. However, most currently reported lead-free dielectric ceramics have limitations, including an unclear local phase structure, and inverse correlation between polarization and dielectric breakdown strength. These issues can be well solved by establishing the relationship between structure and performance. Herein, we enhanced both the polarization and dielectric breakdown strength of BaTiO3-based ferroelectric ceramics by tailoring the temperature corresponding to the maximum dielectric permittivity to room temperature and decreasing the grain size. We confirmed the existence of a tetragonal phase structure in the relaxor BaTiO3-based ferroelectric ceramics. The simultaneously enhanced polarization and breakdown strength can be derived from the distortion of octahedral [TiO6] in the lattice and improved insulation performance. Finally, an ultrahigh recoverable energy density (Wrec) of 4.23 J/cm3 and efficiency (η) of 93.40% with decent stability (variation of Wrec ≤ 9.76% over 20–190 °C, Wrec ≤ 2.25% in 1–100 Hz, and Wrec ≤ 1.78% after 5000 cycles) were simultaneously achieved in the novel BaTiO3-based ceramics. This study may provide a feasible and paradigmatic approach to develop high performance dielectrics for energy storage applications.