Combinatorial Optimization of Grain Size and Domain Morphology Boosts the Energy Storage Performance in (Bi_0.5Na_0.5)TiO₃-Based Dielectric Ceramics

Lead-free dielectric ceramics exhibiting excellent energy storage capacity, long service life, and good safety have been considered to have immense prospects in next-generation pulsed power capacitors. However, it is still challenging to simultaneously achieve large recoverable energy density ( W rec ), high efficiency (η), and excellent charge–discharge performance. Herein, we fabricated lead-free (1 – x )(Bi 0.5 Na 0.5 )TiO 3 - x (Sr 0.7 Bi 0.1 La 0.1 )TiO 3 ((1 – x )BNT- x SBLT) dielectric ceramics, and a good balance between W rec ∼ 4.15 J/cm 3 and η ∼ 93.89% under 333 kV/cm, as well as superior charge–discharge properties (power density P D ∼ 185.42 MW/cm 3, discharge energy density W d ∼ 2.2 J/cm 3, and discharge time t 0.9 ∼ 53.8 ns under 250 kV/cm), was achieved in 0.6BNT–0.4SBLT ceramics. The good energy storage performance can be attributed to the synergistic contributions of significantly enhanced E b caused by grain refinement and the large Δ P values induced by polar nanoregions (PNRs) under a high external electric field. Moreover, the 0.6BNT–0.4SBLT ceramics also present excellent temperature stability of energy storage properties (the variations of W rec and η less than 0.45% and 0.14%, respectively) over a temperature range of 25–185 °C. These figures of merit make 0.6BNT–0.4SBLT ceramics the most promising candidate for energy storage capacitors in advanced pulse power systems.