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 (E_b). 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 Na_0.5Bi_0.5TiO₃ (NBT) system, modified by high-entropy material (Na_1/6Bi_1/6Ca_1/6Sr_1/6Nd_1/6Li_1/6)TiO₃ (NBCSNLT). For the (1-x)NBT-xNBCSNLT bulk ceramics, our findings indicate that E_b consistently increases with the NBCSNLT content, effectively resolving the paradox for electric field above 550 kV/cm. This leads to simultaneously high E_b and large P. Consequently, an ultrahigh recoverable energy-storage density (W_rec) of 18.2 J/cm³, a high efficiency (η) of 85.6%, and a record-breaking energy-storage potential (W_rec/E_b) 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-E_b paradox, paving the way for ultrahigh energy-storage density.