Combinatorial Optimization of Grain Size and Domain Morphology Boosts the Energy Storage Performance in...

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_0.5Na_0.5)TiO₃-x(Sr_0.7Bi_0.1La_0.1)TiO₃ ((1 - x)BNT-xSBLT) dielectric ceramics, and a good balance between W_rec ∼ 4.15 J/cm³ and η ∼ 93.89% under 333 kV/cm, as well as superior charge-discharge properties (power density P_D ∼ 185.42 MW/cm³, discharge energy density W_d ∼ 2.2 J/cm³, 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 ΔP 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.