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

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 (Wrec) 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 Wrec ~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.

Local Diverse Polarization Optimized Comprehensive Energy‐Storage Performance in Lead‐Free Superparaelectrics

“…[ 12 ] Higher activity and external electric field response can be provided by smaller PNRs, resulting in decreased loss and enhanced thermal breakdown strength. [ 7 ] Furthermore, the random distribution behavior can also be observed in polarization magnitude mapping along [100] c and [110] c (Figure S3a,b, Supporting Information). As counted in Figure 3g,h, weak ferroelectricity with small average ferroelectric displacement ((100) c : ≈8.32 pm; (110) c : ≈6.86 pm) exhibits strong dielectric relaxation behavior in BT–BNT–NN sample at superparaelectric region.…”

“…The strategy of constructing phase boundary was designed to obtain excellent comprehensive energy‐storage properties in AgNbO 3 (AN)‐based ceramics. [ 4 ] For relaxor ferroelectrics, many strategies, such as composition adjustment, [ 5 ] domain/nanodomain engineering, [ 6 ] high‐entropy design [ 7 ] were proposed to improve the energy‐storage performance. Unfortunately, in addition to high‐entropy strategy, there is no effective design to realize ultrahigh energy storage density ( W rec ≥ 10 J cm −3 ) in relaxor ferroelectrics, making them comparable to relaxor antiferroelectric energy storage ceramics in competitiveness and development potential.…”

High entropy design: a new pathway to promote the piezoelectricity and dielectric energy storage in perovskite oxides

“…Recently, Chen's group proposed a high-entropy strategy to successfully promote piezoelectric and energy storage performance in perovskite oxide ceramics by tuning the polarization configuration [Acta Mater. 236 (2022) 118115 -high entropy piezoelectrics Pb(Ni,Sc,In,Ti,Nb)O 3 [17] ; Nat. Commun.…”

“…It is well known that different elements have different valence states, ionic radii, electronic configurations, electronegativity and polarizabilities. In recent studies, the high-entropy concept has been tuned to enable various elements, such as Ni 2+ , Mg 2+ , Sc 3+ , Yb 3+ , In 3+ , Zr 4+ , Hf 4+ , Ti 4+ , and Nb 5+ , to simultaneously occupy equivalent lattice sites, such as B-sites, in perovskites to enhance the local polarization fluctuation as much as possible, achieving the effect of increasing entropy [17] . After introducing multiple components, as shown in Figure 1A, large-scale transition regions (green color) that are spread out over the whole area demonstrate the high flexibility of this unique polarization configuration.…”

High-entropy strategy applied to dielectric energy storage

“…Very recently, a breakthrough was made in high-energy-density dielectrics by two independent research groups [1,2] who leveraged the high-entropy strategy to substantially improve the energy storage density of inorganic ferroelectric materials. High-entropy materials, with multiple elements occupying the equivalent lattice sites, possess unique structural characteristics that may secure intriguing material properties [3] .…”