Giant energy-storage density with ultrahigh efficiency in lead-free relaxors via high-entropy design.

Chen, Liang; Deng, Shiqing; Liu, Hui; Wu, Jie; Qi, He; Chen, Jun · Nat Commun · 2022

basic_science · Level V

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Abstract

Next-generation advanced high/pulsed power capacitors rely heavily on dielectric ceramics with high energy storage performance. However, thus far, the huge challenge of realizing ultrahigh recoverable energy storage density (W<sub>rec</sub>) accompanied by ultrahigh efficiency (η) still existed and has become a key bottleneck restricting the development of dielectric materials in cutting-edge energy storage applications. Here, we propose a high-entropy strategy to design "local polymorphic distortion" including rhombohedral-orthorhombic-tetragonal-cubic multiphase nanoclusters and random oxygen octahedral tilt, resulting in ultrasmall polar nanoregions, an enhanced breakdown electric field, and delayed polarization saturation. A giant W<sub>rec</sub> ~10.06 J cm<sup>-3</sup> is realized in lead-free relaxor ferroelectrics, especially with an ultrahigh η ~90.8%, showing breakthrough progress in the comprehensive energy storage performance for lead-free bulk ceramics. This work opens up an effective avenue to design dielectric materials with ultrahigh comprehensive energy storage performance to meet the demanding requirements of advanced energy storage applications.