Excellent Energy Storage Properties Research Articles

Dielectric ceramics with excellent energy storage properties were obtained by doping 0.92NaNbO3-0.08Bi(Ni0.5Zr0.5)O3 ceramics

With the rapid development of the electronic component industry, studies are focusing on achieving a higher energy storage density in smaller volumes. In this study, 0.8 (0.92NaNbO3-0.08Bi(Ni0.5Zr0.5)O3)-0.2(Bi0.5Na0.5)0.7Sr0.3TiO3(0.2BNST) energy storage ceramics with a high maximum breakdown field strength (Eb) and excellent recoverable energy storage density (Urec) are prepared using a solid-state sintering method. A low grain size is obtained in synergy by incorporating sintering aids and linear materials to achieve a breakdown field strength of 655 kV/cm while obtaining Urec = 8.6 J/cm3 and η = 83.5%. In addition, the 0.2BNST ceramic exhibit good dielectric stability in the frequency range of 1–100 Hz at temperatures up to 100 °C. The 0.2BNST ceramic achieve high power density (PD = 107.7 MW/cm3), high current density (CD = 1196.7 A/cm2), and relatively fast discharge rate (t0.9 = 45 ns). These results indicate that 0.2BNST ceramics can potentially become high-performance energy storage capacitors.

Processable nanoarchitectonics of two-dimensional metallo-supramolecular polymer for electrochromic energy storage devices with high coloration efficiency and stability

Two-dimensional porous metallo-supramolecular polymers (MSPs) have shown promising prospects for electrochemical-controlled functional devices as their highly reversible metal-centered redox chemistry. However, parallel efforts to solution-processable large-area uniform film based on high-quality MSPs have encountered with limited success. Herein, we develop a scalable method for synthesizing MSP-Fe with "gram" scale by coordinating 1,3,5-tris(4-(2,2′:6′,2″-terpyridyl)phenyl)benzene with Fe(II) ions. The uniform MSP-Fe film is assembled on a transparent conductive substrate by electrostatic spray technology. The obtained MSP-Fe films exhibit excellent electrochromic performance and energy storage property simultaneously, such as ultrahigh coloration efficiency of 1103.9 ( ± 100) cm2 C−1, fast switching speed (< 1.5 s), large optical contrast (> 71.7%), and high specific capacity (12.01 mAh g−1). More importantly, the degradation of optical contrast is only 3% after 10,000 cycles, proving the remarkable cycle stability of the MSP-Fe film. We further demonstrate a smart energy-storage indicator assembled by the MSP-Fe films, in which the energy-storage level is visually perceptible and recognizable in real-time. Furthermore, a large-area semi-solid-state electrochromic device (225 cm2) is successfully constructed based on MSP-Fe films, which achieves a uniform, fast, and reversible color variation across the device.

Structure, dielectric, and relaxor properties of BaTiO3-modified high-entropy (Bi0.2Na0.2K0.2Ba0.2Ca0.2)TiO3 ceramics for energy storage applications

High-entropy (1−x)Bi0.5Na0.5K0.5Ba0.5Ca0.5TiO3-xBaTiO3 (BNKBCT-BT, x = 0.02, 0.06, 0.10, 0.14 and 0.20) ceramics are successfully prepared via the solid-state reaction method. The XRD and Raman analyses reveal that all samples exhibit a pseudo-cubic phase structure. With increasing x, the a is gradually increased, resulting in the expansion of unit cell volume. A strong frequency dispersion appeared around Tm, demonstrating that the as-prepared ceramics is a relaxor ferroelectric. Owing to the increase in the degree of lattice disorder, as well as relaxation and thermal evolution of PUs, the as-prepared ceramics exhibit a broad relaxor behavior. The ΔP is effectively increased by doping BT, which is conducive to achieving excellent energy storage properties. Moreover, Wrec of all samples is more than 1.31 J/cm3 and, at x = 0.20, Wrec reaches the maximum value of 2.24 J/cm3 at 140 kV/cm. These results indicate that high-entropy (1−x)BNKBCT-xBT ceramics are promising materials for energy storage applications.

Superior energy storage properties in lead-free Na0.5Bi0.5TiO3-based relaxor ferroelectric ceramics via compositional tailoring and bandgap engineering

Currently, lead-free ferroelectrics have been paid much attention due to their versatile applications, environmental friendliness and excellent energy storage properties (ESP). In this work, lead-free relaxor ferroelectrics (0.74-x)Na0.5Bi0.5TiO3-0.06BaTiO3-0.2SrTiO3-xBi(Mg0.5Zr0.5)O3 with superior ESP were successfully designed via compositional tailoring and bandgap engineering. A new peak was observed in the dielectric properties, corresponding to the phase transition from the R3c polar nano regions (PNRs) to the P4bm PNRs, which were consistent with the Rietveld refined XRD and TEM SAED analyses, in which superlattice spots for R3c and P4bm were observed. A recoverable energy storage density (Wrec) of 6.57 J/cm3 and an energy conversion efficiency of 88.6% were procured for ceramics with x = 0.16 at 355 kV/cm. Furthermore, a variation within 5% in Wrec was obtained over a wide temperature and frequency range. Moreover, a power density of 77.39 MW/cm3 and a discharge speed of 52.5 ns were also achieved at 180 kV/cm.

Excellent dielectric energy storage properties of barium titanate based Pb-free ceramics through composition modification and processing improvement

To acquire electric capacitors with enhanced energy storing performance, a composition embellishment and process improvement strategy were adopted. A serial of lead-free (Ba0.875Bi0.125) (Li0.0625Nb0.0625Ti0.875)O3(BBLNT) ceramics were prepared via both conventional solid-state method and viscous polymer processing technology (VPP). The BBLNT-VPP ceramics achieved an ultrahigh energy storing density of 5.34 J/cm3 and a reasonable efficiency of 88% at 470 kV/cm. In addition, the ceramics have particularly extraordinary temperature stability of Wrec2.8 J/cm3, △η2.5% over 30–150 °C, as well as excellent frequency stability with Wrec3.46 J/cm3, η88%, △Wrec±2.7% and △η±4% in the range of 5–300 Hz. Meanwhile, the power density of the ceramic remained above 84.04 MW/cm3 when the temperature was increased from room temperature to about 150 °C, indicating the ceramics possess great promise. Therefore, the BBLNT-VPP ceramics with excellent properties obtained in this work can be potentially applied in dielectric capacitors.

Dielectric properties of a linear polymer-matrix composite filled with aligned Ag@BaTiO3 flakes

Composites with linear dielectric properties possess advantages in energy storage fields for the high charge-discharge efficiency with low energy loss. However, energy density of them is limited due to low permittivity. Here, a linear dielectric polydimethylsiloxane (PDMS) composite filled with parallel aligned core-shell Ag@BaTiO3 (BT) 2D flakes is prepared by directional shearing, which possesses high permittivity and excellent energy storage properties. Compared with traditional polymer/core-shell hybrid filler composites, this work presents modified filler composition, different filler dimension and enhanced energy storage performances. Conformably-coated Ag@BT flakes are prepared through simultaneous hydrolysis on polyvinylpyrrolidone-functionalized Ag flakes, forming a smooth ∼100 nm thick coating layer. The aligned PDMS/40 vol% Ag@BT flake composite exhibits a very high permittivity of 347 and a low dielectric loss< 0.03 at 100 Hz from 20 to 150 °C. The comp°site exhibits an enhanced breakdown strength of 26 kV cm−1 owing to BT coverage-shell blocking and parallel filler arrangement, compared with that of percolative composites filled with metal particles without shell-coverage. The composite exhibits linear dielectric characteristics with high discharged energy density of 6.18 × 10−3 J cm−3 and superhigh charge-discharge efficiency> 95% at 20 kV cm−1. This study demonstrates Ag@BT flake based linear-polymer composites for energy related applications.

Enhanced dielectric and energy storage performances of Hf0.6Zr0.4O2 thin films by Al doping

Hf- and Zr-based oxide thin films, which have various polarization characteristics depending on the crystal structure, have been intensively studied for application in various semiconductor devices due to their excellent electrical properties and complementary metal oxide semiconductor process compatibility. Especially, when the tetragonal phase is implemented, they exhibit a high dielectric constant with anti-ferroelectric properties. Therefore, in this study, the effect of Al doping in HfZrO2 thin films was investigated from the viewpoint of the realization of a high dielectric constant and a stable anti-ferroelectric phase. Through a small amount of Al doping, the crystal structure was modulated from monoclinic to tetragonal. Also, the polarization characteristics were observed in the change of ferroelectric to anti-ferroelectric. Owing to the formation of a tetragonal structure, the dielectric constant was improved up to 41, and the leakage current density remarkably decreased by more than one order of magnitude. Moreover, the Al-doped HfZrO2 thin film with anti-ferroelectricity exhibited excellent energy storage properties with an energy storage density and efficiency of about 53.3 J/cm3 and 76% at ±4.5 MV/cm, respectively. Therefore, we propose that Al-doped HfZrO2 thin film could be applied as a candidate material for next-generation charge storage devices.

Domain-Enhanced Energy Storage, Piezoelectric, and Dielectric Properties in Pb(Zr0.52Ti0.48)O3/SrTiO3 Ferroelectric Superlattices

The domain structure and ferroelectric properties are highly sensitive to interfacial strain and electrostatic interaction in the ferroelectric superlattices. Here, we fabricated a series of [Pb(Zr0.52Ti0.48)O3]m/[SrTiO3]3 (PZTm/STO3) ferroelectric superlattices (m = 2, 3, 6... unit cells) on SrTiO3 (001) substrates by pulsed laser deposition. Compared with pure PZT films, the energy storage density, piezoelectric properties, and dielectric constant of the superlattice are improved. Particularly, the energy storage density, which is increased by about 158%. The modulation of PZT/STO superlattice period thickness effectively improves its dielectric and relaxation properties, which in turn enhances its energy density and efficiency. The mechanism underlying the excellent energy storage properties was revealed by the formation of nanodomains analyzed by a piezoresponse force microscope. Adjusting the electrostatic interactions by changing the periodic thickness of ferroelectric superlattices provides a promising strategy for the design of high-performance sensors and energy-storage devices.

Achieving ultrahigh energy storage properties with superior stability in novel (Ba(1-x)Bix)(Ti(1-x)Zn0.5xSn0.5x)O3 relaxor ferroelectric ceramics via chemical modification

Relaxor ferroelectrics are receiving widespread attention due to their excellent energy storage properties (ESPs). In this study, (Ba(1-x)Bix)(Ti(1-x)Zn0.5xSn0.5x)O3 (abbreviated as BBTZS-x, x = 0.08, 0.10, 0.12, 0.14, 0.16, 0.18) ceramics were synthesized via a solid-state reaction route, and the effects of chemical modification on their structure and properties were investigated in detail. The introduction of Bi/Zn/Sn (BZS) elements into BaTiO3 (BT) systems induced the change from normal to relaxor ferroelectric behavior, which caused the enhancement of comprehensive ESPs. Significantly, BBTZS-0.12 ceramics acquired the preeminent total energy density (Wtot = 5.8 J/cm3), recoverable energy density (Wrec = 4.99 J/cm3) and efficiency (η = 86.1%) at high field strength of 550 kV/cm because of the existence of polar nanoregions (PNRs) therein. The dynamic response of PNRs to the external field was found to be propitious to the enhancement of energy-storage performance. In particular, excellent current density (CD = 721.5 A/cm2), power density (PD = 151.5 MW/cm3) and the time of release of up to 90% of the discharge energy density value (t0.9 = 53 ns) were simultaneously achieved in BBTZS-0.12 ceramics at 420 kV/cm. Moreover, BBTZS-0.12 ceramics were found to be the most optimal for the long-term applications under different environmental conditions because of their outstanding temperature (30–150 °C), frequency (1–500 Hz), and fatigue cycle (cycle numbers: 1–100000) stabilities. Therefore, exceptional ESPs make BBTZS-x ceramics promising for advanced pulsed power capacitors and energy storage applications.

Flexible laterally-configured electrochromic supercapacitor with feasible patterned display

A flexible laterally-configured electrochromic supercapacitor was designed and fabricated through a fully-solution process. The laterally-configured transparent conductive electrode PEDOT:PSS-AgNWs/PET was prepared by spraying technology and then the magenta electrochromic polymer (PProDOT) and gel electrolyte were cast sequentially onto the laterally-configured electrode. The as-prepared device exhibits alternative color changes between magenta and transparent within the potential range −0.9 V and 0.9 V, and the electrochromic behavior is retained even if bent, proving its excellent flexible display properties. As expected, a “ZJUT” patterned flexible display device works clearly when applying driving potentials to the two circuits simultaneously. In addition, the asymmetric device (PProDOT||PEDOT:PSS) integrates excellent electrochromic and electrochemical energy storage properties in terms of high optical contrast of 59.5 %, large coloration efficiency of 423.5 cm2·C−1, fast switching time (7.4 s and 3.9 s), reasonable areal capacitance of 2.15 mF/cm2 at a current density of 0.05 mA/cm2 and robust cyclic stability which can retain 85.65 % and 77.42 % of its initial optical contrast and capacitance even after 1000 cycles of mechanical deformation. Hence, this work demonstrates the flexible laterally-configured electrochromic supercapacitor has great potential in the portable and wearable display fields, such as smart watches and electronic paper.

Constructing graphene conductive networks in manganese vanadate as high-performance cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have been widely studied for their cheapness, safety, as well as high energy and power density. Electrode material plays a dominant role in the electrochemical properties of zinc-ion batteries. Reduced graphene oxide (rGO) can easily interact with compounds via π-π stacking for high-speed electron transport. In this study, The Mn-modified V6O13 material cathode was uniformly loaded onto the rGO conductive network. rGO can release the electron conduction process that limits the performance of the electrode material, and improves the rapid charge and discharge performance of the material. The results show that MnVO@rGO exhibits excellent energy storage properties with a high capacity of 360.3 mAh g−1 at a current density of 0.2 A g−1 in being used as the cathode material for AZIBs. More significantly, even with a current density expansion of a factor of 100, the MnVO@rGO//Zn battery still has a capacity of 88.9 mAh g−1 and a capacity retention rate of over 100% after 10,000 cycles. In addition, it has the maximal energy density of 260.0 Wh kg−1 and power density of 9113.7 W kg−1. This study provides an interesting idea for the development of electrode materials for zinc-ion batteries.

Electrostatic self-assembly of citrus based carbon nanosheets and MXene: Flexible film electrodes and patterned interdigital electrodes for all-solid supercapacitors

Lightweight, flexible, patterned, and environmentally friendly electronic devices should be developed to meet the requirements of future high-tech systems such as smart wearables, internet of things and smart cities. Herein, MXene and citrus-based carbon nanosheet composites (MX/CCNS) with excellent energy storage properties and cyclic stability are prepared via electrostatic self-assembly. MX/CCNS can be easily fabricated as flexible self-supporting electrodes by vacuum filtration and configured as ink for screen printing and large-scale continuous preparation of patterned electrodes. MX/CCNS film electrodes have high specific capacitance (up to 1825.6 mF/cm2 at a current density of 5 mA/cm2) and high cycling stability (99.82% capacity retention after 10,000 cycles). Meanwhile, MX/CCNS can be assembled into flexible all-solid-state and interdigital devices, all exhibiting excellent capacitive performance. The capacitance (114.9 mF/cm2) and energy density (12.9 μWh/cm2) of the printed interdigital supercapacitors are competitive among MXene-based devices. MX/CCNS has great application prospects in scalable and sustainable production of next-generation wearable intelligent electronics.

Enhanced energy storage performance of Bi0.5Na0.5TiO3-based ceramics via grain tuning and relaxor construction

Relaxor ferroelectrics have become competitive candidates in energy storage applications owing to their relatively high maximum polarization, high breakdown strength, and relatively low remnant polarization. Here, Bi0.5Na0.5TiO3 (BNT) with large polarization was selected as the base composition, and Sr0.7Bi0.2Ti0.8Hf0.2O3 (SBTH), as a dopant, was added into BNT to improve its relaxor behavior and decrease the grain size. A series of (1-x)Bi0.5Na0.5TiO3-xSr0.7Bi0.2Ti0.8Hf0.2O3 (abbreviated as (1-x)BNT-xSBTH, x = 0.1, 0.2, 0.3 and 0.4) ceramics were synthesized. The addition of SBTH resulted in the increase in structural disorder, as confirmed by the red-shift in Raman spectra, the enhancement of the relaxor characteristic and the fast response of the domains in local poling measurements. As a result, excellent energy storage properties (with the recoverable energy storage density of 5.5 J/cm3 and efficiency of 85.9 % at 410 kV/cm) were realized in the 0.6BNT-0.4SBTH sample. Moreover, the sample also exhibited excellent thermal stability (20 °C to 200 °C) and frequency insensitivity (0.5–500 Hz). These results suggest that BNT-based relaxor ferroelectric ceramics modulated by SBTH possess great potential in dielectric energy-storage capacitors.

Directional growth of quasi-2D Cu2O monocrystals on rGO membranes in aqueous environments.

The preparation technology of unconventional low-dimensional Cu2O monocrystals, which exhibit specific crystal planes and present significantly unique interfacial and physicochemical properties, is attracting increasing attention and interest. Herein, by integrating a high-temperature oxidation process under vacuum and a pure-water incubation process under ambient conditions, we propose the self-assembled growth and synthesis of quasi-two-dimensional Cu2O monocrystals on reduced graphene oxide (rGO) membranes. The prepared Cu2O crystals have a single (110) crystal plane, regular rectangular morphology, and potentially well conductivity. Experimental and theoretical results suggest that this assembly is attributed to the pre-nucleation clusters aggregation and directional attachment of Cu and O on the rGO membranes in aqueous environment and cation-π interactions between the (110) crystal plane of Cu2O and rGO surface. Our findings offer a potential avenue for the discovery and design of advanced low-dimensional single-crystal materials with specific interfacial properties in a pure aqueous environment.

Enhanced energy storage performance of Bi0.5K0.5TiO3-based ceramics via composition modulation

To meet the booming demands for advanced pulse power systems, developing dielectric ceramics with excellent energy storage performance is extremely urgent. In this work, a composition modulation strategy was adopted for designing Bi0.5K0.5TiO3-based ceramics. That is, incorporating Bi(Mg0.5Hf0.5)O3 into 0.6Bi0.5K0.5TiO3-0.4Sr0.7Bi0.2TiO3 matrix (abbreviated as (1-x)(BKT-SBT)-xBMH, x = 0.00, 0.04 and 0.08). The energy storage performance of the (1-x)(BKT-SBT)-xBMH ceramics was enhanced by increasing the breakdown strength. Ultimately, a recoverable energy density (Wrec) of 4.25 J/cm3 together with an efficiency (η) of 87 % was achieved for the x = 0.04 ceramic at 360 kV/cm. Furthermore, excellent energy storage properties (Wrec ≥ 2.71 J/cm3, η ≥ 85 %) were obtained over a wide range of temperatures (20–200 ℃), frequencies (0.5–100 Hz) and cycle numbers (105) under 260 kV/cm, indicating good thermal stability, frequency-independent character and fatigue-resistance behavior. Our work would open up a new avenue for preparing BKT-based dielectric ceramics.

Low-Temperature Fabrication of TiC Nanotube Arrays by Molten Salt Electrolysis for Supercapacitor Application

A strategy for the synthesis of nanostructured metal carbides that can convert oxides into carbides while maintaining their original nanomorphology is proposed in this study. TiC nanotube arrays (TiC NTAs) were successfully prepared by electrodeoxidation and carbonization in a low-temperature molten salt (600 °C) using TiO2 nanotube arrays (TiO2 NTAs) as precursors. The effects of different factors on the heritability of nanostructures are discussed in detail. TiC NTAs have a highly ordered and directional array structure, a large specific surface area, excellent electrical conductivity, and outstanding chemical stability. Quasi-solid-state supercapacitors based on TiC NTA electrodes exhibit excellent electrochemical energy storage properties such as low charge transfer resistance, high energy density (4.2 μW h cm–2), and excellent cycle stability (90% retention after 10,000 cycles). This study demonstrates a high-performance supercapacitor nanoarray material and provides a general method to synthesize nanostructured metal carbides.

MXene/carboxymethylcellulose-polyaniline (Ti3C2Tx/CMC-PANI) film as flexible electrode for high-performance asymmetric supercapacitors

Two-dimensional (2D) MXene (Ti3C2Tx) materials have received widespread attention as potential electrodes for supercapacitors due to their solution processability, metallic conductivity and excellent energy storage properties. Unfortunately, the self-stacking and interlayer interactions of Ti3C2Tx flakes cause them to acquire poor electrochemical characteristics. Herein, the interwoven carboxymethylcellulose-polyaniline (CMC-PANI) composites were prepared by in-situ polymerization of aniline on the surface of CMC, which was subsequently used as the intercalators to expand the layer spacing of Ti3C2Tx nanosheets via a facile self-assembly process. The interwoven CMC-PANI bridges horizontal Ti3C2Tx nanosheets to construct interconnected conductive and ion channels, making the internal structure of the Ti3C2Tx/CMC-PANI (TCP) film more uniformly and orderly, thereby achieving a high mechanical strength (≈ 35.6 MPa). Meanwhile, the TCP film exhibits a maximum area specific capacitance of 1161.4 mF cm−2 (812.9 mC cm−2) at 1 mA cm−2, and a superior rate performance (maintains 58.4% of the initial value at 50 mA cm−2). Moreover, the fabricated asymmetric supercapacitor (ASC) device presents a high area energy density of 158.7 µW h cm−2 at a power density of 700.1 µW cm−2 and good cycle stability (retention of 89.6% after 15,000 charging/discharging cycles). This rational design balancing flexibility and electrochemical performance provides a broadened idea to solve the inherent defects of MXene and further develop high performance energy storage devices.

Enhancement of recoverable energy density and efficiency of K0.5Na0.5NbO3 ceramic modified by Bi(Mg0.5Zr0.5)O3

As one of the most popular lead-free energy storage materials, K0.5Na0.5NbO3 (KNN)-based ceramics are expected to replace lead-based ceramics due to their high dielectric constant, high Curie temperature, and environmental friendliness. However, the high remnant polarization (Pr) and low breakdown strength (BDS) of KNN ceramic lead to its low energy storage properties, which limits its applications in energy storage field. In this work, the energy storage properties of KNN ceramic were improved by reducing average grain size and enhancing relaxor behavior. The 0.85K0.5Na0.5NbO3-0.15Bi(Mg0.5Zr0.5)O3 (0.85KNN-0.15BMZ) ceramic prepared by the solid state method not only has high recoverable energy storage density value (Wrec) of 3.47 J cm-3 but also has high energy storage efficiency value (η) of 89.14% at a high applied electric field of 320 kV/cm. In addition, the Wrec and η of 0.85KNN-0.15BMZ ceramic fluctuate slightly over the whole temperature range of 20–120 °C at 200 kV/cm, showing excellent temperature stability. At the same time, it can be concluded by first-order reversal curve distribution that 0.85KNN-0.15BMZ ceramic has excellent energy storage properties due to their enhanced relaxor behavior. In summary, the 0.85KNN-0.15BMZ ceramic can be used as the novel dielectric capacitor materials.

Realizing simultaneously excellent energy storage and discharge properties in AgNbO3 based antiferroelectric ceramics via La3+ and Ta5+ co-substitution strategy

AgNbO3 based antiferroelectric (AFE) ceramics have large maximum polarization and low remanent polarization, and thus are important candidates for fabricating dielectric capacitors. However, their energy storage performances have been still large difference with those of lead-based AFEs because of their room-temperature ferrielectric (FIE) behavior. In this study, novel La3+ and Ta5+ co-substituted AgNbO3 ceramics are designed and developed. The introduction of La3+ and Ta5+ decreases the tolerance factor, reduces the polarizability of B-site cations and increases local structure heterogeneity of AgNbO3, which enhance AFE phase stability and refine polarization-electric field (P–E) loops. Besides, adding La3+ and Ta5+ into AgNbO3 ceramics causes the decrease of the grain sizes and the increase of the band gap, which contribute to increased Eb. As a consequence, a high recoverable energy density of 6.79 J/cm3 and large efficiency of 82.1%, which exceed those of many recently reported AgNbO3 based ceramics in terms of overall energy storage properties, are obtained in (Ag0.88La0.04)(Nb0.96Ta0.04)O3 ceramics. Furthermore, the discharge properties of the ceramic with discharge time of 16 ns and power density of 145.03 MW/cm3 outperform those of many lead-free dielectric ceramics.

Large (anti)ferrodistortive NaNbO3-based lead-free relaxors: Polar nanoregions embedded in ordered oxygen octahedral tilt matrix

Relaxor ferroelectric perovskites have experienced a revival of interest in recent years accompanying the deeply exploration of the fine local structure of polar nanoregions, which are thought to be the structure root for unique electrical properties. Interestingly, a new type of low-tolerance relaxor ferroelectric, which exhibits both cation displacement and large oxygen octahedral tilt, exhibiting anomalous microdomains were found in NaNbO3-based lead-free perovskites, breaking through the limits of the relaxor ferroelectric models proposed from classical relaxors. Atomic-scale annular bright-field scanning transmission electron microscopy images indicate that the microdomains are formed by long-range ordered oxygen octahedral tilt. At the same time, substructure of randomly embedded nanoregions with inhomogeneous polarization vectors can be mapped, being the main reason for relaxor behavior. Based on this special ferroelectric-improper ferroelastic state, delayed polarization saturation can be obtained under strong electric field, providing an opportunity for generating excellent energy storage properties. The results found in this work not only open up a new kind of relaxor ferroelectrics but also will lead to the reconstruction of relaxor models and theories built for more than half a century.