Outstanding Energy-Storage Density Together with Efficiency of above 90% via Local Structure Design

Abstract

Dielectric ceramic capacitors with high recoverable energy density (W rec ) and efficiency (η) are of great significance in advanced electronic devices. However, it remains a challenge to achieve high W rec and η parameters simultaneously. Herein, based on density functional theory calculations and local structure analysis, the feasibility of developing the aforementioned capacitors is demonstrated by considering Bi 0.25 Na 0.25 Ba 0.5 TiO 3 (BNT−50BT) as a matrix material with large local polarization and structural distortion. Remarkable W rec and η of 16.21 J/cm 3 and 90.5% have been achieved in Bi 0.25 Na 0.25 Ba 0.5 Ti 0.92 Hf 0.08 O 3 via simple chemical modification, which is the highest W rec value among reported bulk ceramics with η greater than 90%. The examination results of local structures at lattice and atomic scales indicate that the disorderly polarization distribution and small nanoregion (∼3 nm) lead to low hysteresis and high efficiency. In turn, the drastic increase in local polarization activated via the ultrahigh electric field (80 kV/mm) leads to large polarization and superior energy storage density. Therefore, this study emphasizes that chemical design should be established on a clear understanding of the performance-related local structure to enable a targeted regulation of high-performance systems.

Insights into Strain Engineering: From Ferroelectrics to Related Functional Materials and Beyond

“…To satisfy these requirements, a series of methods, represented by polymorphic nanodomain engineering in the BaTiO 3 –BiFeO 3 –SrTiO 3 ternary system, superparaelectric phase design in the SmO-doped BiFeO 3 –BaTiO 3 solid solution, and a high-entropy strategy in (K,Na)­NbO 3 ceramic and Bi-layered films, , has been developed to accomplish nanopolar instability and concomitant high-energy storage. Certainly, the local lattice strain between nanophases and the chemical pressure induced by chemical dopants or point defects play indispensable roles in the manipulation of local polar fluctuations. − However, the intricate interactions and chemical flexibility hinder the decoupling of the pure lattice-strain effect. Recent studies have revealed the evolution of polar nanoregions in the established Pb­(Mg,Nb)­O 3 –PbTiO 3 relaxer under the modulation of various epitaxial strain states .…”

Improved energy storage properties achieved in NaNbO3-based relaxor antiferroelectric ceramics via anti-parallel polar nanoregion design

“…Recently, researchers have made considerable investments in lead-free relaxor ferroelectric/antiferroelectric ceramics, which include NaNbO 3 (NN), 3,4 K 0.5 Na 0.5 NbO 3 (KNN), 5,6 BaTiO 3 (BT), 7,8 Bi 0.5 Na 0.5 TiO 3 (BNT), 9–11 and BiFeO 3 (BF) 12,13 ceramics. With a 3.4 eV broad band gap and significant polarization responses, NN-based ceramics are regarded as one of the potential choices among them.…”