Ultrahigh Energy-Storage Density of BaTiO₃-Based Ceramics via the Interfacial Polarization Strategy

Lead-free dielectric capacitors are excellent candidates for pulsed power devices. However, their low breakdown strength (E_b) strongly limits their energy-storage performance. In this study, Sr_0.7Bi_0.2TiO₃ (SBT) and Bi(Mg_0.5Hf_0.5)O₃ (BMH) were introduced into BaTiO₃ (BT) ceramics to suppress interfacial polarization and modulate the microstructure. The results show that the introduction of SBT and BMH increases the band gap width, reduces the domain size, and, most importantly, successfully attenuates the interfacial polarization. Significantly enhanced E_b values were obtained in (1 - x)(0.65BaTiO₃-0.35Sr_0.7Bi_0.2TiO₃)-xBi(Mg_0.5Hf_0.5)O₃ (BSBT-xBMH) ceramics. Meanwhile, the interfacial polarization was reduced to near zero in the sample with x = 0.10, achieving an ultrahigh E_b (64 kV/mm) and a very large recoverable energy-storage density (W_rec ≈ 9.13 J/cm³). In addition, the sample has excellent thermal stability (in line with EIA-X7R standards) and frequency stability. These properties indicate that the BSBT-0.10BMH ceramic holds promising potential for the application of pulsed power devices.