High-entropy engineered Bi0.47Na0.47Ba0.06TiO3-based weakly coupled relaxor ferroelectrics with quasi-linear polarization for enhanced energy storage performance

• Entropy-driven design of weakly coupled relaxor behavior in BNT-based ceramics enhanced energy storage performance. • Two new methods are introduced to evaluate the quasi-linear polarization response behavior. • High W rec of 7.29 J/cm 3 and η of 88.75 % are achieved in BNT-based ceramics. • The optimal ceramics possess excellent frequency and temperature stabilities. Dielectric capacitor-based electrostatic energy storage technology has been widely employed in advanced pulsed power systems. However, achieving high energy density ( W rec ) and energy efficiency ( η ) at high electric fields remains a challenge due to the effects of early polarization saturation and high polarization hysteresis. In this work, (Bi 0.5 Na 0.5 )TiO 3 -based ceramics, prepared via high-entropy engineering, exhibit both excellent W rec of 7.29 J/cm 3 and η of 88.75 % under an electric field of 680 kV/cm. On the one hand, the entropy-driven enhancement of local random fields induces a quasi-linear P - E hysteresis loop, enabling rapid increase of W rec under high electric fields. Simultaneously, the high η under high electric fields is maintained due to the reversibility of the polar nano-regions (PNRs) and absence of the electric field-induced RFE-FE (relaxor ferroelectric to ferroelectric) phase transition. Moreover, the ceramic exhibits excellent stability in energy storage with respect to temperature (Δ W rec < 6.6 %, Δ η < 5.5 %, 25–200 °C) and frequency (Δ W rec < 9.2 %, Δ η < 4.1 %, 5–160 Hz). This work demonstrates that entropy-driven modulation of polarization behavior is a feasible approach for designing advanced capacitors.