Ultrahigh Energy Storage in Tungsten Bronze Dielectric Ceramics Through a Weakly Coupled Relaxor Design

Abstract

Dielectric energy‐storage capacitors, known for their ultrafast discharge time and high‐power density, find widespread applications in high‐power pulse devices. However, ceramics featuring a tetragonal tungsten bronze structure (TTBs) have received limited attention due to their lower energy‐storage capacity compared to perovskite counterparts. Herein, a TTBs relaxor ferroelectric ceramic based on the Gd0.03Ba0.47Sr0.485‐1.5xSmxNb2O6 composition, exhibiting an ultrahigh recoverable energy density of 9 J cm−3 and an efficiency of 84% under an electric field of 660 kV cm−1 is reported. Notably, the energy storage performance of this ceramic shows remarkable stability against frequency, temperature, and cycling electric field. The introduction of Sm3+ doping is found to create weakly coupled polar nanoregions in the Gd0.03Ba0.47Sr0.485Nb2O6 ceramic. Structural characterizations reveal that the incommensurability parameter increases with higher Sm3+ content, indicative of a highly disordered A‐site structure. Simultaneously, the breakdown strength is also enhanced by raising the conduction activation energy, widening the bandgap, and reducing the electric field‐induced strain. This work presents a significant improvement on the energy storage capabilities of TTBs‐based capacitors, expanding the material choice for high‐power pulse device applications.

High-entropy relaxor ferroelectric ceramics for ultrahigh energy storage

“…The random distribution of site atoms is contemplated to be the structural origin of the enhanced relaxor behavior of TTB ceramics 26 , 31 , 46 , which induces structural disorder and disturbances of B-site polarity displacement, thus inducing a phase transition from normal ferroelectric to relaxor ferroelectric by impeding the stabilization of long-range ferroelectric ordering 30 , 47 , 48 . As for SBPLNN high-entropy ceramics, five ions with large radius differences occupying the two coordination sites (A1 and A2) yield enhanced local compositional inhomogeneity, which results in local structure disorder and polar fluctuations and ultimately modulates the relaxor features 49 .…”

Achieving high overall energy storage performance of KNN-based transparent ceramics by ingenious multiscale designing

“…Despite their faster charge–discharge speed over the other three most commonly used battery systems, which are Li-ion batteries, fuel cells, and super-capacitors, energy storage capacitors have been suffering from the drawback of short battery life for quite a long time, 1–6 and their development was thus limited. Such a problem is mainly due to the paradox of obtaining large polarization and high electric breakdown strength simultaneously, which have already been reported in many previous studies.…”