Design of High-Entropy Relaxor Ferroelectrics for Comprehensive Energy Storage Enhancement

For an ideal electrostatic energy storage dielectric capacitor, the pursuit of simultaneously high energy density and efficiency presents a formidable challenge. Typically, under an applied electric field, an increase in energy density is usually accompanied with a deteriorated energy storage efficiency due to the escalated hysteretic loss, which is harmful to the reliability of the capacitor. Thus, a well-balanced performance of improved energy density and maintained high efficiency is highly demanded. In this work, a structure with amorphous phases embedded in polycrystalline nanograins using the entropy tactic, leading to a higher transport barrier of carrier is constructed. Hence, the hysteretic loss is largely suppressed at a high electric field and the high polarization is still sustained in the high-entropy film. Consequently, an ultrahigh energy density of 139.5 J cm-3 with a high efficiency of 87.9%, and a high figure of merit of 1153 are simultaneously achieved in the high-entropy Ba2Bi4Ti5O18-based relaxor ferroelectric. This work offers a promising avenue in materials structure design for advanced high-power energy storage applications. With the increased electric field, Energy density increases, while the efficiency is sacrificed due to the escalated hysteretic loss, deteriorating the reliability of the capacitor. Balancing the trade-off between energy density and efficiency in dielectric capacitors is highly in demand. The high entropy design tactic helps to achieve a high overall energy storage performance figure of merit UF = Ue/(1 - eta). image