Breaking polarization-breakdown strength paradox for ultrahigh energy storage density in NBT-based ceramics

Dielectric capacitors are crucial in contemporary electronic devices for storing and recycling electric energy. However, their energy-storage density is significantly hindered by the paradox between polarization (P) and breakdown strength (Eb). Herein, we propose a strategy to overcome the paradox through a unique high-entropy design aimed at regulating phase structure and minimizing interfacial polarization. This approach ensures an ample polar phase while providing a sufficiently high field to induce a transition from antiferroelectric to ferroelectric, significantly enhancing polarization. This strategy has been successfully applied to the Na0.5Bi0.5TiO3 (NBT) system, modified by high-entropy material (Na1/6Bi1/6Ca1/6Sr1/6Nd1/6Li1/6)TiO3 (NBCSNLT). For the (1-x)NBT-xNBCSNLT bulk ceramics, our findings indicate that Eb consistently increases with the NBCSNLT content, effectively resolving the paradox for electric field above 550 kV/cm. This leads to simultaneously high Eb and large P. Consequently, an ultrahigh recoverable energy-storage density (Wrec) of 18.2 J/cm3, a high efficiency (η) of 85.6%, and a record-breaking energy-storage potential (Wrec/Eb) value of 0.026 mC/cm2, were achieved in the bulk 0.55NBCSNLT. Additionally, this sample exhibited excellent temperature/frequency stability. This strategy provides an effective pathway for surmounting the P-Eb paradox, paving the way for ultrahigh energy-storage density.