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 rec ) 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 rec ~10.06 J cm −3 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. 

/pdf/giant-energy-storage-density-with-ultrahigh-efficiency-in-1bwyasc1.pdf

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

High-entropy enhanced capacitive energy storage

Dielectric ceramic capacitors have attracted increasing attention as advanced pulsed power devices and modern electronic systems owing to their fast charge/discharge speed and high power density. However, it is challenging to meet the urgent needs of lead-free ceramics with superior energy storage performance in practical applications. Herein, a strategy for the composition and structural modification is proposed to overcome the current challenge. The lead-free ceramics composed of BiFeO3 -SrTiO3 are fabricated. A low hysteresis and high polarization can be achieved via composition optimization. The experimental results and finite element simulations indicate that the two-step sintering method significantly influences the decrease in the grain size and improvement in the breakdown strength (EBDS ). A high EBDS of ≈750 kV cm-1 accompanied by a large maximum polarization (≈40 µC cm-2 ) and negligible remanent polarization (<2 µC cm-2 ) contribute to the ultrahigh energy density and efficiency values of the order of 8.4 J cm-3 and ≈90%, respectively. Both energy density and efficiency exhibit excellent stability over the frequency range of 1-100 Hz and temperatures up to 120 °C, along with the superior power density of 280 MW cm-3 , making the studied BiFeO3 -SrTiO3 ceramics potentially useful for high-power energy storage applications.

Composition and Structure Optimized BiFeO3 -SrTiO3 Lead-Free Ceramics with Ultrahigh Energy Storage Performance.

Developing environmentally friendly lead-free dielectric ceramics with ultrahigh energy storage performance is fundamental to next-generation high-power capacitors but challenging as well. Herein, a record-breaking ultrahigh energy efficiency η of 97.8%...

Superior energy storage performance in (Bi0.5Na0.5)TiO3-based lead-free relaxor ferroelectrics for dielectric capacitor application via multiscale optimization design

Supercritical relaxor nanograined ferroelectrics are demonstrated for high‐performance dielectric capacitors, showing record‐high overall properties of energy density ≈13.1 J cm−3 and field‐insensitive efficiency ≈90% at ≈74 kV mm−1 and superior charge–discharge performances of high power density ≈700 MW cm−3, high discharge energy density ≈6.67 J cm−3, and ultrashort discharge time <40 ns at 55 kV mm−1. Ex/in situ transmission electron microscopy, Raman spectroscopy, and synchrotron X‐ray diffraction provide clear evidence of the supercritical behavior in (Na,K)(Sb,Nb)O3–SrZrO3–(Bi0.5Na0.5)ZrO3 ceramics, being achieved by engineering the coexistence of multiple local symmetries within the ergodic relaxor zone. The vanished difference between the ground relaxor state and the high‐field supercritical state eliminates polarization hysteresis. The supercritical evolution with electric field enables a highly delayed polarization saturation with continuously increased polarization magnitudes. The results demonstrate that such a design strategy of compositionally induced and field‐manipulated supercritical behavior can be generalizable for developing desirable energy‐storage dielectrics for applications in ceramic/film capacitors.

Supercritical Relaxor Nanograined Ferroelectrics for Ultrahigh‐Energy‐Storage Capacitors

Electrostatic energy storage technology based on dielectrics is fundamental to advanced electronics and high-power electrical systems. Recently, relaxor ferroelectrics characterized by nanodomains ...

Hongbao Yao

Papers

Ultrahigh energy storage in superparaelectric relaxor ferroelectrics