Achieving superior energy-storage efficiency by tailoring the state of polar nano-sized regions under low electric fields

The development of high-performance electrostatic energy storage dielectrics is essential for various applications such as pulsed-power technologies, electric vehicles (EVs), electronic devices, and the high-temperature aviation sector. However, the usage of lead as a crucial component in conventional high-performance dielectric materials has raised severe environmental concerns. As a result of this, there is an urgent need to explore lead-free alternatives. Ferroelectric ceramics offer high energy density but lack stability at high temperatures. Here we present a lead-free (1 − x)BiFeO 3 −xCaTiO 3 (x = 0.6, 0.7, and 0.8; BFO-CTO) ceramic capacitor with low dielectric loss, high thermal stability, and high energy density up to ∼200 °C. The introduction of CTO (x = 0.7) to the BFO matrix triggers a transition from the normal ferroelectrics to the relaxor ferroelectrics state, resulting in a high recoverable energy density of 1.18 J cm −3 at 190 °C with an ultrafast dielectric relaxation time of 44 μs. These results offer a promising, environmentally friendly, high-capacity ceramic capacitor material for high-frequency and high-temperature applications.

Section: Introductionmentioning

confidence: 99%

High Energy Density Achieved in Novel Lead-Free BiFeO₃–CaTiO₃ Ferroelectric Ceramics for High-Temperature Energy Storage Applications

Gomasu,

Saha,

Ghosh

et al. 2024

“…Unlike the typical (Na 0.5 Bi 0.5 )TiO 3 (NBT) matrix with strong FE properties, which is often used to form RFEs, − (Na 0.5 Bi 0.5 ) 0.7 Sr 0.3 TiO 3 (NBST) doped with 30 mol % Sr 2+ ions at the A-site of NBT has been widely studied for its equally large P m of 47.2 μC/cm 2 but lower P r of 8.2 μC/cm 2 . However, the W rec of NBST is too low to meet the application requirements owing to premature polarization saturation, and so much effort has been made to improve its W rec by introducing Bi(Mg 2/3 Nb 1/3 )O 3 , Bi(Ni 0.5 Sn 0.5 )O 3 , and Sr(Ti 0.85 Zr 0.15 )O 3 .…”

Section: Introductionmentioning

confidence: 99%

Enhanced Energy Storage Properties in Lead-Free (Na_0.5Bi_0.5)_0.7Sr_0.3TiO₃-Based Relaxor Ferroelectric Ceramics through a Cooperative Optimization Strategy

Wang

Zhang

Shi

et al. 2023

Although relaxor ferroelectrics have been widely investigated owing to their various advantages, there are still impediments to boosting their energy-storage density (W rec) and energy-storage efficiency (η). In this paper, we propose a cooperative optimization strategy for achieving comprehensive outstanding energy-storage performance in (Na0.5Bi0.5)0.7Sr0.3TiO3 (NBST)-based ceramics by triggering a nonergodic-to-ergodic transformation and optimizing the forming process. The first step of substituting NaNbO3 (NN) for NBST generated an ergodic state and induced polar nanoregions under the guidance of a phase-field simulation. The second step was to apply a viscous polymer process (VPP) to the 0.85NBST-0.15NN ceramics, which reduced porosity and increased compactness, resulting in a significant polarization difference and high breakdown strength. Consequently, 0.85NBST-0.15NN-VPP ceramics optimized by this cooperative two-step strategy possessed improved energy-storage characteristics (W rec = 7.6 J/cm3, η = 90%) under 410 kV/cm as well as reliable temperature adaptability within a range of 20–120 °C, outperforming most reported (Na0.5Bi0.5) TiO3-based ceramics. The improved energy-storage performance validates the developed ceramics’ practical applicability as well as the advantages of implementing a cooperative optimization technique to fabricate similar high-performance dielectric ceramics.

“…However, a large polarization hysteresis still exists in NN-based ceramics with the AFE P phase. Relaxor ferroelectrics (RFEs) not only possess saturation polarization similar to that of antiferroelectric but also high η, owing to the strong relaxation and the polar nanoregions (PNRs). , Similar to RFEs, the AFE R phase usually exhibits an extremely small remnant polarization and an increased driving electric field of the AFE-FE phase transition ( E AF ), according to the enhanced relaxor behavior and the existence of the AFE polar nanodomain. Therefore, various strategies, e.g., phase structure modulation, domain engineering, etc., aiming at disrupting the long-range antiferroelectric order to make the AFE R phase stable at room temperature, have been exploited to resolve the dilemma of large P r .…”

Section: Introductionmentioning

confidence: 99%

Achieving Ultrahigh Energy Storage Performance for NaNbO₃-Based Lead-Free Antiferroelectric Ceramics via the Coupling of the Stable Antiferroelectric R Phase and Nanodomain Engineering

Wei,

Duan,

Zhou

et al. 2023

NaNbO 3 (NN)-based lead-free eco-friendly antiferroelectric (AFE) ceramics with an extremely high maximum polarization (P m ) are believed to be a promising alternative to traditional lead-based ceramics. Nevertheless, the high energy dissipation resulting from the large polarization hysteresis, which arises from the AFE-ferroelectric (FE) phase transition, poses a great challenge to the application of this promising ceramic. Herein, an excellent recoverable energy storage density (W rec ) was attained by intentionally designing a (0.86 − x) NaNbO 3 -0.14CaTiO 3 -xBiMg 2/3 Nb 1/3 O 3 (NN-CT-xBMN) relaxor antiferroelectric ceramic, attributed to the synergistic effect of the stable AFE R phase and nanodomain engineering to overcome the bottleneck. The obtained results illustrate that the inclusion of BMN causes the transition from AFE microdomains to nanodomains and stabilizes the relaxor AFE orthorhombic R phase, which generates a highly stable polarization field response with low hysteresis and delays the AFE-FE phase transition, thus improving energy storage density. As a consequence, a high W rec of 5.41 J cm −3 with an excellent conversion efficiency η of 86.7% was obtained in the NN-CT-0.08BMN ceramic. Moreover, the NN-CT-0.08BMN ceramic exhibits superior stability in temperature (25−150 °C), frequency (1−600 Hz), and fatigue behavior (10°−10 4 cycles) together with a large current density (C D = 810 A cm −2 ), ultrahigh power density (P D = 118 MW cm −3 ), and ultrafast discharge rate (t 0.9 < 0.7 μs). This superior energy storage density, coupled with outstanding stability, suggests that the NN-CT-0.08BMN ceramic has the potential to be a promising candidate for pulsed power applications and power electronics.