Breaking polarization-breakdown strength paradox for ultrahigh energy storage density in NBT-based ceramics
Wenjun Cao, Yanwei Wu, Xiaoyu Yang, Daqin Guan, Xuecen Huang, Feng Li, Youmin Guo, Chunchang Wang, Binghui Ge, Xu Hou, Zhenxiang Cheng
Abstract
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. Energy storage ceramics typically face a trade-off between polarization and breakdown strength. Here, the authors overcome the paradox through a unique high-entropy design aimed at regulating phase structure and minimizing interfacial polarization.