High-Entropy Composition Design for Achieving Excellent Energy Storage Performance in (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃-Based Ceramics

Lead-free dielectric capacitors display a huge potential in pulsed power energy storage systems. However, how to realize superior recoverable energy storage density ( W rec ) and efficiency (η) in dielectric materials remains a major challenge. Herein, a high-entropy strategy based on (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 TiO 3 with a morphotropic phase boundary composition is developed to gain superior comprehensive energy storage characteristics. The energy storage capabilities are significantly regulated by high-entropy composition design, which induces the destruction of long-range ferroelectric ordering, inhibition of grain growth, optimization of relaxation behavior, increase in resistivity, and widening of band gap, promoting the improvement of polarization difference and electric breakdown strength ( E b ). Ultimately, excellent W rec (∼7.57 J/cm 3 ) and η (81.8%) under a great E b ∼ 572 kV/cm are realized in the 0.9[((Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 ) 0.65 (Ca 0.5 Sr 0.5 ) 0.35 ]TiO 3 -0.1(Bi 0.9 Nd 0.1 )(Mg 0.5 Zr 0.5 )O 3 high-entropy ceramic. Meanwhile, prominent temperature, frequency, and cycle stability as well as charge–discharge performance are also exhibited in the corresponding sample. These results confirm the feasibility of the studied high-entropy composition for advanced energy storage applications.