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 (Wrec) and efficiency (η) in dielectric materials remains a major challenge. Herein, a high-entropy strategy based on (Bi0.5Na0.5)0.94Ba0.06TiO3 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 (Eb). Ultimately, excellent Wrec (∼7.57 J/cm3) and η (81.8%) under a great Eb ∼ 572 kV/cm are realized in the 0.9[((Bi0.5Na0.5)0.94Ba0.06)0.65(Ca0.5Sr0.5)0.35]TiO3-0.1(Bi0.9Nd0.1)(Mg0.5Zr0.5)O3 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.