Phase and Band Structure Engineering via Linear Additive in NBT-ST for Excellent Energy Storage Performance with Superior Thermal Stability

Abstract

Lead-free relaxor ferroelectric ceramics with ultrahigh energy-storage performance are vital for pulsed power systems. We herein propose a strategy of phase and band structure engineering for high-performance energy storage. To demonstrate the effectiveness of this strategy, (1 − x)(0.75Na 0.5 Bi 0.5 TiO 3 -0.25SrTiO 3 )-xCaTi 0.875 Nb 0.1 O 3 (NBT-ST-xCTN, x = 0.1, 0.2, 0.3, 0.4, and 0.5) samples were designed and fabricated via the solidstate reaction method. The linear dielectric CTN was used as a modulator to tune both phase and band structures of the tested system. Our results show that both rhombohedral phase (R-phase) and tetragonal phase (T-phase) coexist in the samples. The R/T ratio decreases, while the band gap increases with increasing CTN content. The best energy-storage properties with large energy storage density (W rec = 7.13 J/cm 3 ), a high efficiency (η = 90.3%), and an ultrafast discharge time (25 ns) were achieved in the NBT-ST-0.4CTN sample with R/T = 0.121. Importantly, along with its excellent energy-storage performance, the sample exhibited superior thermal stability with the variations of W rec ≤ 7% and η ≤ 10% over the wide temperature range of 233−413 K. This work suggests that this engineering of phase and band structures is a promising strategy to achieve superior energy-storage properties in lead-free ceramics.

Outstanding Energy Storage Performance of NBT-Based Ceramics under Moderate Electric Field Achieved via Antiferroelectric Engineering

“…Meanwhile, compared to current reports, these values are superior to those of the most lead-free energy storage ceramics under MEFs (∼200–300 kV/cm) as compared in Figure h. The comparison of the W rec – E relationship between the x = 0.04 sample and other lead-free energy-storage ceramics also highlights that the MEF-energy-storage performance of the present sample rivals all the counterparts. ,,− …”

“…The Raman spectra were deconvoluted (Lorentzian area type) using PeakFit software. All Raman peaks are broad and diffuse, mainly due to the free occupation of Na/Bi/Sr/Ca/Ag ions at the A-site . As the ACN content increases, the peaks related to the Ti–O bonding vibration (200–400 cm –1 , corresponding to A and B modes) and TiO 6 octahedral vibration (500–600 cm –1 , corresponding to C and D modes) move away from each other.…”

Interfacial Polarization Restriction for Ultrahigh Energy‐Storage Density in Lead‐Free Ceramics

“…Considering that CT has a large energy gap (3.4 eV) with high resistivity [28] and La 3+ refines grains, [29] the introduction of CLT into NBT modifies the resistivities of the grain and ground boundary, as well as the grain and grain boundary ratio, thereby modifying the interfacial polarization. Our results demonstrate this critical phenomenon, and a very high E b of 64 kV mm −1 was obtained in 38 mol.% CLT-modified sample in which the Δφ is reduced to a value close to zero.…”

“…To illustrate the effectiveness of this proposal, (Na 0.5 Bi 0.5 )TiO 3 ‐BaTiO 3 (NBT‐BT) was selected as the model system, and linear dielectric Ca 0.7 La 0.2 TiO 3 (CLT) was used as an additive to modify the interfacial polarization. Considering that CT has a large energy gap (3.4 eV) with high resistivity [ 28 ] and La 3+ refines grains, [ 29 ] the introduction of CLT into NBT modifies the resistivities of the grain and ground boundary, as well as the grain and grain boundary ratio, thereby modifying the interfacial polarization. Our results demonstrate this critical phenomenon, and a very high E b of 64 kV mm −1 was obtained in 38 mol.% CLT‐modified sample in which the Δϕ is reduced to a value close to zero.…”

Ultrahigh Energy-Storage Density of BaTiO3-Based Ceramics via the Interfacial Polarization Strategy

“…Because of the dependence on an applied electric field rather than chemical reactions, dielectric ceramic capacitors can rapidly store and release energy via polarization and depolarization. With the continuous miniaturization of electronic devices, the existing dielectric ceramic capacitors are gradually struggling to meet the requirements of miniaturization because of their low recoverable energy-storage density ( W rec ) and efficiency (η). − Therefore, there is a top priority to explore eco-friendly ceramics that can achieve both a large W rec and a high η.…”