Ultra-high energy storage performance in Bi₅Ti₃Mg₂/₃Nb₁/3O₁₅ film induced by defect dipole engineering

The rapid rate of charging and discharging, along with the high power density exhibited by dielectric energy storage films, has attracted considerable attention. However, the limited energy density hinders the broader utilization of dielectric energy storage films. The clamping relationship between the intensity of polarization and the breakdown electric field imposes a clear constraint on further enhancing the energy storage density in dielectric films for energy storage. We inserted BiMg2/3Nb1/3O3 into Bi4Ti3O12, thereby promoting the formation of a defect dipole system characterized by an enhanced polarization intensity to address the aforementioned issues. Furthermore, the incorporation of La3+ ions intensified defect polarization intensity in Bi5Ti3Mg2/3Nb1/3O15 film, optimized relaxation behavior, widened the band gap, and reduced oxygen vacancy concentration. The synergistic enhancement of polarization intensity, breakdown of electric field, and relaxation behavior can be achieved. The clamping relationship among polarization intensity, breakdown electric field and relaxation behavior is resolved within a specific range in this study. Finally, the Bi4LaTi3Mg2/3Nb1/3O15 film enables the achievement of a high recyclable energy density (96.3 J/cm(3) @ 3137 kV/cm) and superior energy efficiency (eta similar to 82.2 %). The present study introduces a novel idea to overcome the clamping relationship and attain improved energy storage performance.