Synergistically enhancing relaxation and breakdown strength to optimize energy storage performance in BaTiO3-based ceramics

To meet the increasing demand for green and low-carbon development, increasingly stringent performance criteria have been established for both the recoverable energy storage density ( W rec ) and the energy storage efficiency ( η ) of dielectric energy storage capacitors. In this work, Zr 4+ ions were introduced into the B-sites of the 0.9[0.88BaTiO 3 -0.12Bi(Mg 2/3 (Nb 0.85 Ta 0.15 ) 1/3 )O 3 ]-0.1Bi 0.5 Na 0.5 TiO 3 (BT-BMNT-BNT) weakly coupled relaxor ferroelectric ceramics to enhance the structural disorder of the ceramics, which facilitates the formation of polar nanoregions (PNRs). The emergence of PNRs intensifies the relaxor behavior of the ceramics, thereby reducing remanent polarization ( P r ) and maintaining high η . Furthermore, the incorporation of Zr 4+ ions significantly enhanced the insulating properties of the ceramics, leading to a substantial increase in the breakdown electric field ( E b ). Consequently, the W rec and η of the optimized BT-BMNT-BNT-0.2Zr ceramic reached 5.43 J/cm 3 and 91.77% at 620 kV/cm, representing a substantial improvement in enhancing the energy storage performance of BT-based ceramics. In addition, the BT-BMNT-BNT-0.2Zr ceramic exhibits excellent pulse performances, including an exceptional discharge energy density ( W D ≈3 J/cm 3 ), an ultra-short discharge time ( t 0.9 ≈48 ns), and excellent thermal stability ( W D variation < +8.9%, 25 °C-180 °C) and fatigue resistance ( W D variation < +9.5%, within 450 cycles). These results demonstrate the strong potential of the BT-BMNT-BNT-0.2Zr ceramic for advanced dielectric energy storage capacitor applications.