Ultrahigh energy-storage capacity achieved in (Bi0.5Na0.5)TiO3-based high-entropy dielectric capacitors with linear-like polarization response

Dielectric capacitors have gained much attention in next-generation advanced pulse power systems owing to their ultrafast charging/discharging rate. However, the early polarization saturation and large hysteresis hinder the enhancement of recoverable energy-storage density (Wrec) with increasing electric field. Here, we design (Bi0.5Na0.5)TiO3-based high-entropy dielectric capacitors to modulate polarization behavior and maximize the energy storage capacity. An ultrahigh Wrec of 7.6 J/cm3, together with a high η of 90% is simultaneously obtained, showing great competitiveness among the (Bi0.5Na0.5)TiO3-based energy storage ceramics. On the one hand, the linear-like P-E loops induced by enhanced random field, which is achieved by increasing the atomic configurational entropy, delay the polarization saturation and ensure the rapid enhancement of Wrec under higher electric fields. On the other hand, the high efficiency (η) is assured due to the existence of polar nanoregions (PNRs) and the absence of relaxor ferroelectric to ferroelectric transition. Noticeably, the ceramic also exhibits excellent thermal stability (ΔWrec < 4.4%, Δη < 10.3%, −50–200 °C), cycling stability (ΔWrec < 0.085%, Δη < 0.12%, 1–105) and frequency stability (ΔWrec < 7.08%, Δη < 3.79%, 1–200 Hz). This work reveals that regulating the entropy is an effective method to design high-performance dielectric capacitors.