- Email: [email protected]
Superior comprehensive energy storage properties in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics
Journal Pre-proofs Superior comprehensive energy storage properties in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics Xiaoshuang Qiao, Fudong Zhang, Di Wu, Bi Chen, Xumei Zhao, Zhanhui Peng, Xiaodan Ren, Pengfei Liang, Xiaolian Chao, Zupei Yang PII: DOI: Reference:
S1385-8947(20)30149-2 https://doi.org/10.1016/j.cej.2020.124158 CEJ 124158
To appear in:
Chemical Engineering Journal
Received Date: Revised Date: Accepted Date:
7 November 2019 7 December 2019 17 January 2020
Please cite this article as: X. Qiao, F. Zhang, D. Wu, B. Chen, X. Zhao, Z. Peng, X. Ren, P. Liang, X. Chao, Z. Yang, Superior comprehensive energy storage properties in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics, Chemical Engineering Journal (2020), doi: https://doi.org/10.1016/j.cej.2020.124158
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2020 Published by Elsevier B.V.
Superior comprehensive energy storage properties in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics
Xiaoshuang Qiaoa, Fudong Zhanga, Di Wua, Bi Chena, Xumei Zhaoa, Zhanhui Penga, Xiaodan Rena, Pengfei Liangb, Xiaolian Chaoa†, Zupei Yanga†
aKey
Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Key Laboratory for
Advanced Energy Devices, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, 710062, Shaanxi, China. bSchool of Physics & Information Technology, Shaanxi Normal University, Xi’an, 710062, Shaanxi, China
† Corresponding
authors shall be addressed at:
Key Laboratory for Macromolecular Science of Shaanxi Province School of Materials Science and Engineering Shaanxi Normal University, Xi'an, 710062, Shaanxi, P.R. China Tel: +86-29-8153-0718; Fax: +86-29-8153-0702 E-mail addresses: [email protected] and [email protected]
Abstract Seeking for high energy storage materials has become an urgent task in the circumstance of energy crisis. In this work, a series of relaxor ferroelectrics (1-x)Bi0.5Na0.5TiO3-xSr0.7La0.2TiO3 ((1-x)BNT-xSLT) with excellent energy storage performance were successfully fabricated. The SLT as a second component was doped into BNT and served three main functions: (1) efficiently decreased the grain size and increased the band gap and thus enhanced the breakdown electric field, (2) drove the ferroelectric phase gradually to a relaxor character, (3) reduced the tolerance factor (t) to defer the electric field of polarization saturation. Eventually, we achieved an impressive recoverable energy storage density (Wrec) of 4.14 J/cm3 and an ultrahigh energy storage efficiency (ƞ) of 92.2% simultaneously at 315 kV/cm in the ceramic of x = 0.45. Furthermore, the sample also exhibited an excellent stability against testing temperature, frequency and cycle, a high power density (182 MW/cm3) and a fast discharge speed (123 ns), all of which are ideal characteristics for high power energy storage devices. Keywords: Bi0.5Na0.5TiO3; Relaxor ferroelectric; Energy storage; Power density 1. Introduction Over the past few years, dielectric capacitors have gained immense attention owing to their high power density, good thermal stability and fast charge/discharge speed [1-3]. In general, the energy storage performance of a specific dielectric material can be derived from its P-E loop [4-6]: Ps
Wrec Edp Pr
(1)
Wrec 100% Wtotal
(2)
where Ps, Pr, E and are the saturation polarization, remanent polarization, applied electric field and energy storage efficiency, respectively [7-9]. According to Equation (1), we concluded that a large recoverable energy storage density (Wrec) depends on a high breakdown electric field (Eb) and a large ΔP = Ps - Pr. As known, dielectrics materials can be classified into four types according to their character of P-E loops [10]: linear dielectrics, ferroelectrics (FE), antiferroelectrics (AFE) and relaxor ferroelectrics (RFE). The low dielectric constant (r) of linear dielectrics limits their energy
storage
density
despite
their
high
Eb.
For
example,
the
(Ca0.5Sr0.5)0.8875La0.075TiO3 ceramic exhibits large Eb (370 kV/cm) but low Wrec (2.07 J/cm3) [11]. Ferroelectrics (such as pure Bi0.5Na0.5TiO3 (BNT), K0.5Na0.5NbO3 (KNN), and BaTiO3 (BT)) show high Pr and low Eb, thus lead to low Wrec and . This limits their practical applications for energy storage devices. Antiferroelectrics are considered as promising energy storage materials because of their large Wrec which originates from their unique double hysteresis loops, but their relative low energy efficiency and poor cycle stability need to be resolved before any practical application. For instance, despite its large Wrec (4.5 J/cm3), Ag0.88Gd0.04NbO3 shows a low of 65% [12]. Relaxor ferroelectrics with a slender P-E loop are deemed to be promising candidates for energy storage materials, owing to their excellent cycle stability, good thermal stability, high power density and fast charge-discharge rate [13,14]. Currently, BNT-based energy storage ceramics have been extensively
investigated, mainly due to their extremely high Ps (> 40 μC/cm2) [15,16]. However, pristine BNT also exhibits a high Pr (38 μC/cm2) at room temperature, which limits its energy storage density [17]. As known, BNT possesses a slim P-E loop and is considered as a relaxor ferroelectric between 200 °C (Ts) and 320 °C (Curie temperature, Tm). Therefore, by decreasing the Ts of BNT below room temperature, its Pr can be reduced and Wrec can be improved. For the sake of decreasing the Pr and improving the Eb synchronously, various additives were added into BNT. Zhang et al. reported that a large Wrec of 2.35 J/cm3 was achieved in SnO2 doped BNT-SrTiO3 ceramics
[18];
Yang
et
al.
studied
the
film
of
Mn-doped
(1-x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xSrTiO3 and obtained an ultrahigh Wrec of 76.1 J/cm3 [19]; Wu et al. prepared 0.96(0.65BNT-0.35Sr0.85Bi0.1TiO3)-0.04NaNbO3 ceramics with a Wrec of 3.08 J/cm3 [20]. According to the above reports, it can be found that the cubic-structured SrTiO3 (ST) plays an important role in improving the Wrec of BNT-based system. This is because SrTiO3 owns a large Eb (200 kV/cm) and a low Curie temperature (Tm = -250 °C). In our previous study, we doped Bi3+ at Sr2+ site in BNT-ST ceramics (expressed as (1-x)BNT-xSBT), and obtained a slim P-E loop with a higher Ps. However, the breakdown field Eb is still quite low and needs to be improved [21]. In this study, we introduced La3+ into Sr2+ site of BNT-ST ceramics, since it was reported that La3+ doping is beneficial of decreasing the grain size and delaying the electric field of polarization saturation in BNT-based ceramics [22,23]. The effect of SLT doping on the improved energy storage properties for BNT was studied in detail, as schemed in Fig.1.
2. Experimental Ceramics with the nominal compositions of (1-x)Bi0.5Na0.5TiO3-xSr0.7La0.2TiO3 (abbreviated as (1-x)BNT-xSLT, x = 0, 0.2, 0.3, 0.35, 0.45 and 0.5) were synthesized via a standard mixed oxide method. The raw materials of TiO2 (>98.0%), Bi2O3 (>98.9%), Na2CO3 (>99.8%), SrCO3 (>99.0%) and La2O3 (>99.99%) were selected as the raw materials and ball-milled for 24 h, after dried, calcined the different components of powder at 850 °C for 3 hours. Finally, pressed the powders into pellets and then sintered at 1150-1200 °C for 3 h. The Archimedes drainage method was used to determine the mass densities of the ceramics. The ceramics’ crystal structures were investigated by a X-ray diffraction instrument (Rigaku, Japan, Cu K) and a transmission electron microscopy (HR-TEM, JEM-2100, Japan). All the ceramics were polished and thermal etched at 1050 °C for 1 h prior to the observation by a scanning electron microscope (SU3500). The dielectric constant and dielectric loss were recorded by a Agilent E4980A instrument. The samples for measuring energy storage properties were polished to a thickness of ~ 0.2 mm, and both sides were covered by gold electrodes with a diameter of 2 mm. P-E loops of the ceramics were obtained using Radiant P-PM2. A charge-discharge apparatus (CFD-001, Gogo Instruments Technology, China) was employed to estimate the charge-discharge behaviour of the samples. 3. Results and discussion Fig. 2(a) shows the XRD patterns of (1-x)BNT-xSLT ceramics. It is clear that all ceramics exhibit the perovskite structure, suggesting that SLT has completely
dissolved into the BNT host lattice. For pure BNT, the peaks near 40 ° correspond to (003) and (021). With an increase in the SLT content, these peaks become more symmetry and merge into one single peak (111), suggesting the perovskite structure gradually changes from the rhombohedral phase (R3c) to the pseudocubic phase (Pc) [24]. Fig. 2(b) gives the enlarged XRD patterns from 38° to 48°. It is seen that the (111) and (200) peaks gradually move to lower angles as the SLT content increases, implying a lattice expansion due to the replacement of Na+ (139 pm) and Bi3+ (138 pm) ions by larger Sr2+ (144 pm) ions [25]. Fig. 2(c) shows the bright-field TEM image and selected area electron diffraction (SAED) spot for x = 0.45 ceramic. The weak super-lattice reflections of the 1/2{ooo} spots (marked by an arrow) indicate the presence of the polar R3c phase along with the pseudocubic lattice, which is contributes to induce high polarization upon applied electric fields [20,26]. According to the energy dispersive X-ray (EDX) mapping in Fig. 2 (d), it can be found that Bi, Na, Sr, La, Ti and O are all uniformly distributed in the x = 0.45 ceramic, this suggests that SLT has well dissolved into BNT lattice and formed a homogeneous solid solution, which is consistent with the XRD results. The thermally etched (1-x)BNT-xSLT ceramics are depicted in Fig. 3(a-f). All samples exhibit clear grain boundaries, dense microstructures and minor pores. With increasing SLT content, the relative density (r) of the ceramics increases gradually, while the average grain size decreases significantly, suggesting that SLT alloying not only improves the density but also prevents the grain growth in BNT ceramics [27]. It is well-known that high r and small grain size are beneficial for improving
breakdown electric field. The reduction of grain size can be explained as follows. First, the smaller ions of Na+ (1.39 Å) and Bi3+ (1.38 Å) are replaced by larger ions of Sr2+ (1.44 Å), which increases the lattice strain energy (ΔGstrain), thus the grain boundary mobility is inhibited [28]. Second, the contents of volatile Na+ and Bi3+ decrease gradually with an increase in the SLT content, thus the concentration of oxygen vacancy is reduced, which restrains the grain growth [29]. The breakdown electric field is not only affected by extrinsic factors such as the porosity and grain size, but also by intrinsic factors such as the band gap (Eg) and dielectric constant. Eg is the energy required by electrons to jump from the top of the valence band to the bottom of the conduction band, which can be calculated by the Tauc equation:
h 2 A(h E g )
(3)
where hv, A and α are photon energy, a constant and absorption coefficient, respectively
[8].
The
ultraviolet-visible
(UV-Vis)
absorbance
spectra
of
(1-x)BNT-xSLT ceramics are shown in Fig. 4(a). With an increase in the SLT content, the Eg increases gradually, and samples of x = 0, 0.2, 0.3 and 0.45 display an Eg of 3.07, 3.09, 3.12 and 3.17 eV, respectively. Fig. 4(c) shows the complex impedance plots of (1-x)BNT-xSLT ceramics. The ceramcs’ resistivity becomes larger as the SLT content increases, which can be determined from the intersection of the x-axis with the semicircular arc at low-frequency. The activation energy of the ceramics are calculated using the Arrhenius formula and shown in Fig. 4(d). It can be seen that the activation energy increases from 0.74 eV for x =0 to 0.97 eV for x = 0.45, suggesting
that the oxygen vacancy concentration decreases as the SLT content increases [6]. To sum up, the higher band gap, larger resistivity and lower oxygen vacancy concentration are beneficial for improving the breakdown electric field of (1-x)BNT-xSLT ceramics [11]. The dielectric constant (εr) and loss tangent (tanδ) of (1-x)BNT-xSLT ceramics as the function of temperature are displayed in Fig. 5(a). There are two dielectric peaks exist in the εr-T curves (Ts and Tm). Ts is originated from the thermal evolution of discrete polar nanoregions (PNRs), and the other anomaly Tm is caused by the transition of rhombohedral PNRs to tetragonal PNRs [14]. The values of Ts, Tm and εm (εr corresponding to Tm) for (1-x)BNT-xSLT samples are shown in Table 1, and exhibit the same decreasing tendency with increasing of SLT. Furthermore, a widened dielectric constant platform can be found between Ts and Tm as the SLT content increases. SLT doping into BNT induced the random electric fields (RFS) by the increased disorder degree and ion charge fluctuation at A-site. Since the RFs can enhance the relaxor behavior of ferroelectrics, the two dielectric peaks of the ceramics gradually weakened and widened, the εm notably decreased along with the εs (εr corresponding to Ts) changed slightly, resulting in a good temperature stability of the dielectric constant. Similar phenomena have been observed in other BNT-based ceramics [30-32]. The rate of change of dielectric constant (ε/ε150°C, ε = εr-ε150°C) as a function of temperature of the ceramics is displayed in Fig. 5(b), it can be seen that the samples of 0.3 ≤ x ≤ 0.45 exhibit excellent temperature stability according to the standard of variation of dielectric constant being less than ± 15%. The specific
temperature ranges of (1-x)BNT-xSLT ceramics are shown in Table 1. Of particular important is that all ceramics put up lower tanδ (< 0.07) between -150 °C - 350 °C. The values of tanδ at room temperature for the samples are shown in Table 1, and the decreased tanδ reduces the amount of heat, resulting in large breakdown electric field [33]. The ferroelectric properties of (1-x)BNT-xSLT ceramics were tested at 120 kV/cm and 10 Hz, and the results are displayed in Fig 4(c-d). Pristine BNT is identified as a typical ferroelectric with a saturated hysteresis loop, and two current peaks can be observed in the I-E curve which corresponds to the coercive field (Ec) [34]. With the increase of SLT, the P-E loops become thinner and nearly linear, suggesting the long-range ordered ferroelectric domains are broken and the relaxation behavior gets enhanced [35]. The relevant values of Ps and Pr are exhibited in Table 1. Four current peaks start to emerge (denoted as ±EF and ±ER) in the I-V curves (x ≥ 0.2), implying the reversible phase transition of RFE and FE exists in these samples [16]. The intensity of current peaks becomes weaker and eventually obscure as the SLT content increases; meanwhile, the electric field becomes larger for the phase transition of EF (shown in Table 1), implying an increase of RFE phase [22], which is conducive to delay the electric field of polarization saturation [15]. The aforementioned results can probably be attributed to the decrement of tolerance factor ( t (rA rO ) / 2 (rB rO ) ), since SLT has a smaller t of 0.945 than the 0.982 for BNT. The ceramics (0.2 ≤ x ≤ 0.5) were tested from 100 kV/cm to their breakdown electric fields, and the results are given in Fig. 6(a). With increasing SLT content, Eb
is improved gradually from 151 to 180, 228, 315 and 338 kV/cm for x = 0.2, x = 0.3, x = 0.35, x = 0.45 and x = 0.5, respectively, the increased Eb can be ascribed to the decreased grain size and dielectric loss. Fig. 6(b) shows the dependence of P on applied electric fields for different ceramics. Notably, the ceramic of x = 0.45 exhibits the largest P and highest Eb synchronously, which are two critical parameters to achieve a large Wrec. Compared to other samples, the sample of x = 0.45 exhibits a large Wrec of 4.14 J/cm3 and a high of 92.2%, as shown in Fig. 6(c). The energy storage properties under different electric fields of x = 0.45 ceramic are displayed in Fig. 6(d), which exhibits that Wrec increases obviously from 0.79 to 4.14 J/cm3 as the electric field increases from 100 to 315 kV/cm; the ƞ decreases slightly from 93.4% to 92.2%, suggesting the good electric field stability of . Figure 5(e) displays the energy storage properties of x = 0.45 sample and other BNT-based ceramics [13,14,16,18,20,24,32,36-42]. We found that the Wrec of BNT-based ceramics are mostly less than 3.5 J/cm3. However, in this work, the Wrec reaches to 4.14 J/cm3, and the result can be attributed to the large P and large Eb of the x = 0.45 ceramic. Figure 5(f) displays a schemed comparison of Wrec and ƞ between our 0.55BNT-0.45SLT sample and other typical lead-free ceramics in literature [11,12,14,20,24,27,36,43-56]. It is well known that the lead-free energy storage ceramics can be divided into BaTiO3-based (BT-), Bi0.5Na0.5TiO3-based (BNT-), K0.5Na0.5NbO3-based (KNN-), AgNbO3-based (AN-), NaNbO3-based (NN-), BiFeO3-based (BF-) and SrTiO3-based (ST-) [57]. Among of them, AN- and KNN- based ceramics exhibit relatively larger Wrec ~ 4 J/cm3; however, their ƞ isn’t high enough for practical application. For BT-
and ST- based ceramics, high ƞ is assured but low Wrec stands as the bottleneck. BNTand BF- based ceramics always exhibit large P because of the hybridization between Bi 6p and O 2p orbitals [4], however, the relatively lower Eb inhibits the realization of large Wrec. In this work, we improved the Eb in (1-x)BNT-xSLT to 315 kV/cm for the specimen of x = 0.45, and realized a large Wrec of 4.14 J/cm3 and a high ƞ of 92% simultaneously. For practical application, the frequency stability and cycle stability are also two very important properties, besides the large Wrec and high η. Fig 6(a) exhibits the frequency dependent P-E loops of the x = 0.45 sample, measured from 5 to 500 Hz under 150 kV/cm, and Fig. 7(b) summarized the energy storage properties. It is seen that the value of Wrec decreases from 1.62 gradually to 1.33 J/cm3 while ƞ varies within only 0.48% as frequency increases from 5 to 500 Hz, suggesting that the sample of x = 0.45 possesses good frequency stability. The P-E loops are not sensitive to frequency can be attributed to the PNRs, due to the polarization response process is dominated by the growth and orientation of PNRs in response to electric fields [15,32]. Fig. 7(c) exhibits the P-E loops from 1 to 105 cycles. As seen, the P-E loops are almost unaffected with cycle number increases, Ps decreases gradually but negligibly from 23.65 to 23.62 µC/cm2, Wrec and ƞ vary a little within 2.8% and 1.2%, respectively (as shown in Fig. 7(d)). These results suggest that the ceramic of x = 0.45 has an excellent cycle stability, which can be attributed to the high quality ceramic with suitable grain size, little pores, highly dynamic PNRs and little defects [43,58].
To analyze the actual charging-discharging capacity of x = 0.45 ceramics, the undamped and overdamped discharge current curves are tested and displayed in Fig. 8. According to Fig. 8(a), we can see that the current peaks increase obviously with the increment of electric field, and the current density (CD) and power density (PD) can be calculated from the curves: CD = Imax/S
(4)
PD = EImax/S
(5)
where S and E represent the electrode area and electric field, respectively [59], and the results are shown in Fig. 8(b). CD and PD exhibit the same evolving tendency, i.e., increase with electric field and reach 1815 A/cm2 and 182 MW/cm3 under 200 kV/cm, respectively. The overdamped discharge current curves at different temperatures and a fixed electric field of 200 kV/cm are shown in Fig. 8(c). The discharge energy density (WD) can be obtained by the following formula: WD = Ri(t)2dt/V
(6)
where V represents the sample volume, load resistance (R) is 300 Ω, and the results are shown in Fig. 8(d)[37]. With increasing of temperature, it can be found that the Wd decreases slightly from 2.31 J/cm3 to 2.08 J/cm3, implying good temperature stability exists in the sample of x = 0.45, besides, the same sample also shows a fast charge-discharge speed t0.9 of 123 ns. Compared to other lead-free ceramics, the sample of x = 0.45 exhibits excellent charge-discharge behavior (Table 2) [6,31,43,44,52,59-62], suggesting its high potential in pulsed power systems application [63].
4. Conclusions In summary, (1-x)BNT-xSLT relaxor ferroelectric ceramics were prepared through a solid-state reaction method. With increasing SLT content, the crystal structure transforms from a rhombohedral phase to a weakly polarized pseudo-cubic phase, the relaxation behavior is enhanced, and the Eb improved from 120 kV/cm for x = 0 to 338 kV/cm for x = 0.5. Furthermore, the electric field of polarization saturation is deferred as the concentration of SLT increase. Ultimately, the sample of x = 0.45 possesses a large Wrec of 4.14 J/cm3 and a high of 92.2%. Moreover, a splendid frequency stability, an excellent fatigue resistance, a large current density (1815 A/cm2) and a high power density (182 MW/cm3) are also obtained in the same sample, enabling the ceramic of 0.55BNT-0.45SLT a hopeful alternative for application in pulse power devices. Acknowledgements This work was supported by the National Science Foundation of China (Grant Nos. 51572163, 51577111 and 51872177), and the Fundamental Research Funds for the Central Universities (Program Nos. GK201802007 and 2018CBLZ007). Conflicts of interest There are no conflicts to declare. References [1] G. Wang, J.L. Li, X. Zhang, Z.M. Fan, F. Yang, A. Feteira, D. Zhou, D.C. Sinclair, T. Ma, X.L. Tan, D.W. Wang, L.M. Reaney, Ultrahigh energy storage density lead-free multilayers by controlled electrical homogeneity. Energy Environ. Sci. 12 (2019) 582-588.
[2] H.S. Wang, Y.C. Liu, T.Q. Yang and S.J. Zhang, Ultrahigh energy-storage density in antiferroelectric ceramics with field-induced multiphase transitions. Adv. Funct. Mater. 29 (2019) 1807321. [3] Z.T. Yang, F. Gao, H.L. Du, L. Jin, L.L. Yan, Q.Y. Hu, Y. Yu, S.B. Qu, X.Y. Wei, Z. Xu and Y.J. Wang, Grain size engineered lead-free ceramics with both large energy storage density and ultrahigh mechanical properties, Nano Energy 58 (2019) 768-777. [4] D.W. Wang, Z.M. Fan, D. Zhou, A. Khesro, S. Murakami, A. Feteira, Q.L. Zhao, X.L. Tan, L.M. Reaney, Bismuth ferrite-based lead-free ceramics and multilayers with high recoverable energy density, J. Mater. Chem. A 6 (2018) 4133-4144. [5] Z.T. Yang, H.L. Du, S.B. Qu, Y.D. Hou, H. Ma, J.F. Wang, J. Wang, X.Y. Wei, Z. Xu, Significantly enhanced recoverable energy storage density in potassium-sodium niobate-based lead free ceramics, J. Mater. Chem. A 4 (2016) 13778-13785. [6] X.S. Qiao, D. Wu, F.D. Zhang, B. Chen, X.D. Ren, P.F. Liang, H.L. Du, X.L. Chao, Z.P. Yang, Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic with large energy density and high efficiency under a moderate electric field, J. Mater. Chem. C 7 (2019) 10514-10520. [7] Z.T. Yang, H.L. Du, L. Jin, Q.Y. Hu, H. Wang, Y.F. Li, J.F. Wang, F. Gao, S.B. Qu, Realizing high comprehensive energy storage performance in lead-free bulk ceramics via designing an unmatched temperature range, J. Mater. Chem. A DOI: 10.1039/c9ta11314b. [8] Q.Z. Chai, D. Yang, X.M. Zhao, X.L. Chao, Z.P. Yang, Lead-free (K,Na)NbO3-based ceramics with high optical transparency and large energy storage ability, J. Am. Ceram. Soc. 101 (2018) 2321-2329. [9] Y. Lin, D. Li, M. Zhang, S. Zhan, Y. Yang, H. Yang, Q. Yuan, Excellent Energy-Storage Properties Achieved in BaTiO3-based lead-free relaxor ferroelectric ceramics via domain engineering on the nanoscale, ACS Appl. Mater. Interfaces 11 (2019) 36824-36830.
[10]T.Q. Shao, H.L. Du, H. Ma, S.B. Qu, J. Wang, J.F. Wang, X.Y. Wei, Z. Xu, Potassium-sodium niobate based lead-free ceramics: novel electrical energy storage materials, J. Mater. Chem. A 5 (2017) 554-563. [11]W. Wang, Y.P. Pu, X. Guo, T. Ouyang, Y. Shi, M.D. Yang, J.W. Li, R.K. Shi, G. Liu, Enhanced energy storage properties of lead-free (Ca0.5Sr0.5)1-1.5xLaxTiO3 linear dielectric ceramics within a wide temperature range, Ceram. Int. 45 (2019) 14684-14690. [12]S. Li, H.C. Nie, G.S. Wang, C.H. Xu, N.T. Liu, M.X. Zhou, F. Cao, X.L. Dong, Significantly enhanced energy storage performance of rare-earth-modified silver niobate lead-free antiferroelectric ceramics via local chemical pressure tailoring, J. Mater. Chem. C 7 (2019) 1551-1560. [13]P. Shi, L.G. Zhu, W.W. Gao, Z.H. Yu, X.J. Lou, X.J. Wang, Z.M. Yang, S. Yang, Large
energy
storage
properties
of
lead-free
(1-x)(0.72Bi0.5Na0.5TiO3-0.28SrTiO3)-xBiAlO3 ceramics at broad temperature range, J. Alloys Compd. 784 (2019) 788-793. [14]Z.B. Pan, D. Hu, Y. Zhang, J.J. Liu, B. Shen, J.W. Zhai, Achieving high discharge energy density and efficiency with NBT-based ceramics for application in capacitors, J. Mater. Chem. C 7 (2019) 4072-4078. [15]H.
Qi,
R.Z.
Zuo,
Linear-like
lead-free
relaxor
antiferroelectric
(Bi0.5Na0.5)TiO3-NaNbO3 with giant energy-storage density/efficiency and super stability against temperature and frequency, J. Mater. Chem. A 7 (2019) 3971-3978. [16]J. Yin, Y.X. Zhang, X. Lv, J.G. Wu, Ultrahigh energy-storage potential under low electric field in bismuth sodium titanate-based perovskite ferroelectrics, J. Mater. Chem. A 6 (2018) 9823-9832. [17]L. Zhang, X.Y. Pu, M. Chen, S.H. Bai, Y.P. Pu, Influence of BaSnO3 additive on the energy storage properties of Na0.5Bi0.5TiO3-based relaxor ferroelectrics, J. Eur. Ceram. Soc. 38 (2018) 2304-2311. [18]L.Y. Zhang, Z.Y. Wang, Y. Li, P. Chen, J. Cai, Y. Yan, Y.F. Zhou, D.W. Wang, G. Liu, Enhanced energy storage performance in Sn doped Sr0.6(Na0.5Bi0.5)0.4TiO3
lead-free relaxor ferroelectric ceramics, J. Eur. Ceram. Soc. 39 (2019) 3057-3063. [19]C.H. Yang, J. Qian, Y.J. Han, P.P. Lv, S.F. Huang, X. Cheng, ZX. Cheng, Design of an all-inorganic flexible Na0.5Bi0.5TiO3-based film capacitor with giant and stable energy storage performance, J. Mater. Chem. A 7 (2019) 22366-22376. [20]Y.C. Wu, Y.Z. Fan, N.T. Liu, P. Peng, M.X. Zhou, S.G. Yan, F. Cao, X.L. Dong, G.S. Wang, Enhanced energy storage properties in sodium bismuth titanate-based ceramics for dielectric capacitor applications, J. Mater. Chem. C 7 (2019) 6222-6230. [21]X.S. Qiao, D. Wu, F.D. Zhang, M.S. Niu, B. Chen, X.M. Zhao, P.F. Liang, L.L. Wei, X.L. Chao, Z.P. Yang, Enhanced energy density and thermal stability in relaxor ferroelectric Bi0.5Na0.5TiO3-Sr0.7Bi0.2TiO3 ceramics, J. Eur. Ceram. Soc. 39 (2019) 4778-4784. [22]F.F. Li, Y.F. Liu, Y.N. Lyu, Y.H. Qi, Z.L. Yu, C.G. Lu, Huge strain and energy storage density of A-site La3+ donor doped (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics, Ceram. Int. 43 (2017) 106-110. [23]X.M. Zhao, X.M. Chen, H.Y. Ma, H.L. Lian, P. Liu, Microstructure, dielectric and
ferroelectric
properties
of
0.97[(Na0.5Bi0.5)1-1.5xLax]TiO3-0.03BaTiO3
lead-free ceramics, J. Alloys Compd. 630 (2015) 236-243. [24]L.T. Yang, X. Kong, Z.X. Cheng, S.J. Zhang, Ultra-high energy storage performance with mitigated polarization saturation in lead-free relaxors, J. Mater. Chem. A 7 (2019) 8573-8580. [25]R.D. Shannon, Revised effective ionic radii and systematic studies of interatomie distances in halides and chaleogenides, Acta Cryst. A32 (1976) 751-767. [26]J.Y. Wu, A. Mahajan, L. Riekehr, H.F. Zhang, B. Yang, N. Meng, Z. Zhang, H.X. Yan, Perovskite Srx(Bi1-xNa0.97-xLi0.03)0.5TiO3 ceramics with polar nano regions for high power energy storage, Nano Energy 50 (2018) 723-732. [27]Y. Huang, F. Li, H. Hao, F.Q. Xia, H.X. Liu, S.J. Zhang, (Bi0.51Na0.47)TiO3 based lead free ceramics with high energy density and efficiency, Journal of Materiomics 5 (2019) 385-393.
[28]J. Boonlakhorn, P. Thongbai, B. Putasaeng, T. Yamwong, S. Maensiri, Very high-performance dielectric properties of Ca1−3x/2YbxCu3Ti4O12 ceramics, J. Alloys Compd. 612 (2014) 103-109. [29]R.A. Malik, A. Hussain, M. Acosta, J. Daniels, H.S. Han, M.H. Kim, J.S. Lee, Thermal-stability of electric field-induced strain and energy storage density in Nb-doped BNKT-ST piezoceramics, J. Eur. Ceram. Soc. 38 (2018) 2511-2519. [30]Y. Yang, H. Wang, L.N. Bi, Q.J. Zheng, G.F. Fan, W.J. Jie, D.M. Lin, High energy storage density and discharging efficiency in La3+/Nb5+-co-substituted (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics, J. Eur. Ceram. Soc. 39 (2019) 3051-3056. [31]L. Zhang, Y.P. Pu, M. Chen, T.C. Wei, X. Peng, Novel Na0.5Bi0.5TiO3 based, lead-free energy storage ceramics with high power and energy density and excellent
high-temperature
stability,
Chem.
Eng.
J.
DOI:
https://doi.org/10.1016/j.cej.2019.123154. [32]W.G. Ma, Y.W. Zhu, M.A. Marwat, P.Y. Fan, B. Xie, D. Salamon, Z.G. Ye, H.B. Zhang, Enhanced energy-storage performance with excellent stability under low electric fields in BNT-ST relaxor ferroelectric ceramics, J. Mater. Chem. C 7 (2019) 281-288. [33]L.T. Yang, X. Kong, F. Li, H. Hao, Z.X. Cheng, H.X. Liu, J.F. Li, S.J. Zhang, Enhanced energy-storage performance with excellent stability under low electric fields in BNT-ST relaxor ferroelectric ceramics, Prog Mater Sci. 102 (2019) 72-108. [34]S. Manotham, P. Butnoi, P. Jaita, N. Kumar, K. Chokethawai, G. Rujijanagul, D.P. Cann, Large electric field-induced strain and large improvement in energy density of bismuth sodium potassium titanate-based piezoelectric ceramics, J. Alloys Compd. 739 (2018) 457-467. [35]S.J. Pang, L. Yang, J.Y. Qin, H. Qin, H. Xie, H. Wang, C.R. Zhou, J.W. Xu, Large electric field-induced strain and large improvement in energy density of bismuth sodium potassium titanate-based piezoelectric ceramics, Appl. Phys. A, 125 (2019) 119.
[36]L. Zhang, Y.P. Pu, M. Chen, Influence of BaZrO3 additive on the energy-storage properties of 0.775Na0.5Bi0.5TiO3-0.225BaSnO3 relaxor ferroelectrics. J. Alloys Compd. 775 (2019) 342-347. [37]L. Zhang, Y.P. Pu, M. Chen, G. Liu, Antiferroelectric-like properties in MgO-modified 0.775Na0.5Bi0.5TiO3-0.225BaSnO3 ceramics for high power energy storage, J. Eur. Ceram. Soc. 38 (2018) 5388-5395. [38]J. Li, F. Li, Z. Xu, S. Zhang, Multilayer lead-free ceramic capacitors with ultrahigh energy density and efficiency, Adv Mater. 30 (2018) 1802155. [39]F. Yan, H. Yang, Y. Lin, T. Wang, Dielectric and ferroelectric properties of SrTiO3-Bi0.5Na0.5TiO3-BaAl0.5Nb0.5O3 lead-free ceramics for high-energy-storage applications, Inorg. Chem. 56 (2017) 13510-13516. [40]B. Hu, H.Q. Fan, L. Ning, Y. Wen, C. Wang, High energy storage performance of [(Bi0.5Na0.5)0.94Ba0.06]0.97La0.03Ti1-x(Al0.5Nb0.5)xO3
ceramics
with
enhanced
dielectric breakdown strength, Ceram. Int. 44 (2018) 15160-15166. [41]C. Wang, F. Yan, H.B. Yang, Y. Lin, T. Wang, Dielectric and ferroelectric properties of SrTiO3-Bi0.54Na0.46TiO3-BaTiO3 lead-free ceramics for high energy storage applications, J. Alloys Compd. 749 (2018) 605-611. [42]Q. Li, W.M. Zhang, C. Wang, L. Ning, C. Wang, Y. Wen, B. Hu, H.Q. Fan, Enhanced
energy-storage
performance
of
(1-x)(0.72Bi0.5Na0.5TiO3-0.28Bi0.2Sr0.7TiO3)-xLa ceramics, J. Alloys Compd. 775 (2019) 116-123. [43]M.X. Zhou, R.H. Liang, Z.Y. Zhou, X.L. Dong, Combining high energy efficiency and fast charge-discharge capability in novel BaTiO3-based relaxor ferroelectric ceramic for energy-storage, Ceram. Int. 45 (2019) 3582-3590. [44]M.X. Zhou, R.H. Liang, Z.Y. Zhou, X.L. Dong, Novel BaTiO3-based lead-free ceramic capacitors featuring high energy storage density, high power density, and excellent stability, J. Mater. Chem. C 6 (2018) 8528-8537. [45]Q.B. Yuan, G. Li, F. Z. Yao, S.D. Cheng, Y.F. Wang, R. Ma, S.B. Mi, M. Gu, K. Wang, J.F. Li, H. Wang, Simultaneously achieved temperature-insensitive high
energy density and efficiency in domain engineered BaTiO3-Bi(Mg0.5Zr0.5)O3 lead-free relaxor ferroelectrics, Nano Energy 52 (2018) 203-210. [46]W.B. Li, D. Zhou, L.X. Pang, R. Xu, H.H. Guo, Novel barium titanate based capacitors with high energy density and fast discharge performance, J. Mater. Chem. A 5 (2017) 19607-19612. [47]Z.N. Yan, D. Zhang, X.F. Zhou, H. Qi, H. Luo, K.C. Zhou, I. Abrahams, H.X. Yan, Silver niobate based lead-free ceramics with high energy storage density, J. Mater. Chem. A 7 (2019) 10702-10711. [48]N.N. Luo, K. Han, F.P. Zhuo, C. Xu, G.Z. Zhang, LJ. Liu, X.Y. Chen, C.Z. Hu, H.F. Zhou, Y.Z. Wei, Aliovalent A-site engineered AgNbO3 lead-free antiferroelectric ceramics toward superior energy storage density, J. Mater. Chem. A 7 (2019) 14118-14128. [49]L. Zhao, Q. Liu, J. Gao, S. Zhang, J. F. Li, Lead-Free Antiferroelectric silver niobate tantalate with high energy storage performance, Adv. Mater. 29 (2017) 1701824. [50]H.G. Yang, H. Qi, R.Z. Zuo, Enhanced breakdown strength and energy storage density in a new BiFeO3 based ternary lead-free relaxor ferroelectric ceramic, J. Eur. Ceram. Soc. 39 (2019) 2673-2679. [51]D.G.
Zheng,
R.Z.
Zuo,
La(Mg1/2Ti1/2)O3-modified
Enhanced
BiFeO3-BaTiO3
energy
storage
lead-free
properties
relaxor
in
ferroelectric
ceramics within a wide temperature range, J. Eur. Ceram. Soc. 37 (2017) 413-418. [52]J.M. Ye, G.S. Wang, M.X. Zhou, N.T. Liu, X.F. Chen, S. Li, F. Cao, X.L. Dong, Excellent comprehensive energy storage properties of novel lead-free NaNbO3-based ceramics for dielectric capacitor applications, J. Mater. Chem. C 7 (2019) 5639-5645. [53]M.X. Zhou, R.H. Liang, Z.Y. Zhou, S.G. Yan, X.L. Dong, Novel sodium niobate-vased lead-free ceramics as new environment-friendly energy storage materials with high energy density, high power density, and excellent stability. ACS Sustain. Chem. Eng. 6 (2018) 12755-12765.
[54]Q. Luo, Z.H. Yao, G.F. Zhang, L. Zhang, J. Xie, H. Hao, M.H. Cao, H.X. Liu, Unfolding dielectric breakdown effects on energy storage performances of modified (Sr0.98Ca0.02)(Ti1-xZrx)O3 ceramics, Int. J. Appl. Ceram. Tec. 15 (2018) 1030-1039. [55]H.B. Yang, F. Yan, Y. Lin, T. Wang, L. He, F. Wang, A lead free relaxation and high energy storage efficiency ceramics for energy storage applications, J. Alloys Compd. 710 (2017) 436-445. [56]H.B. Yang, P.F. Liu, F. Yan, Y. Lin, T. Wang, A novel lead-free ceramic with layered structure for high energy storage applications, J. Alloys Compd. 773 (2019) 244-249. [57]Z.T. Yang, H.L. Du, L. Jin, Q.Y. Hu, S.B. Qu, Z.N. Yang, Y. Yu, X.Y. Wei, Z. Xu, A new family of sodium niobate-based dielectrics for electrical energy storage applications, J. Eur. Ceram. Soc. 39 (2019) 2899-2907. [58]W.Y. Pan, C.F. Yue, O. Tosyali, Fatigue of ferroelectric polarization and the electric field induced strain in lead lanthanum zirconate titanate ceramics, J. Am. Ceram. Soc. 75 (1992) 1534-1540. [59]M.X. Zhou, R.H. Liang, Z.Y. Zhou, X.L. Dong, Superior energy storage properties and excellent stability of novel NaNbO3-based lead-free ceramics with A-site vacancy obtained via a Bi2O3 substitution strategy, J. Mater. Chem. A 6 (2018) 17896-17904. [60]F. Li, X. Hou, J. Wang, H.R. Zeng, B. Shen, J.W. Zhai, Structure-design strategy of 0-3 type (Bi0.32Sr0.42Na0.20)TiO3/MgO composite to boost energy storage density, efficiency and charge-discharge performance, J. Eur. Ceram. Soc. 39 (2019) 2889-2898. [61]F. Li, T. Jiang, J.W. Zhai, B. Shen, H.R. Zeng, Exploring novel bismuth-based materials for energy storage applications, J. Mater. Chem. C 6 (2018) 7976-7981. [62]Y. Yao, Y. Li, N.N. Sun, J.H. Du, X.W. Li, L.W. Zhang, Q.W. Zhang, X.H. Hao, Enhanced
dielectric
and
energy-storage
properties
in
ZnO-doped
0.9(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-0.1NaNbO3 ceramics, Ceram. Int. 44 (2018) 5961-5966.
[63]X.M. Yang, F.P. Zhuo, C.X. Wang, Y. Liu, Z.J. Wang, H. Tailor, C. He, X.F. Long, High energy storage density and ultrafast discharge in lead lutetium niobate based ceramics, J. Mater. Chem. A 7 (2019) 8414-8422.
Fig. 1 Schematic diagram of achieving large Wrec and high simultaneously: Eb is increased by decreasing grain size and increasing band gap; relaxation behavior is enhanced by driving Ts to room temperature; electric field of polarization saturation is delayed by reducing tolerance factor.
Fig. 2 (a) XRD curves of (1-x)BNT-xSLT ceramics, (b) enlarged images of (111) and (200) peaks; (c) bright-field TEM image and SAED spots for region ① , (d) EDX mapping images of 0.55BNT-0.45SLT ceramic.
Fig. 3 SEM images, relative density and grain size distribution of (1-x)BNT-xSLT ceramics: (a) x = 0, (b) x = 0.2, (c) x = 0.3, (d) x = 0.35, (e) x = 0.45, (f) x = 0.5.
Fig. 4 UV-Vis absorbance spectra (a) and (hv)2 vs. hv plots (b) of (1-x)BNT-xSLT ceramics. Complex impedance (c) and activation energy (d) of (1-x)BNT-xSLT ceramics.
Fig. 5 Temperature dependence of dielectric constant and loss tangent at 1 kHz (a), temperature range of ε150°C 15% at 1 kHz (b), P-E loops (c) and I-V curves (d) of (1-x)BNT-xSLT ceramics.
Fig. 6 Unipolar P-E loops at different electric fields (a), variation of P with the electric field (b) and Wrec and ƞ values (c) of (1-x)BNT-xSLT ceramics; ƞ and Wrec values of x = 0.45 ceramic at various electric fields (d). Energy storage properties of x = 0.45 ceramic and previously reported BNT-based ceramics (e), Wrec and ƞ of typical lead-free ceramics (f).
Fig. 7 Frequency and cycle stability of (1-x)BNT-xSLT ceramics at 150 kV/cm.
Fig. 8 Undamped pulsed discharge current curves (a), values of CD and PD at various electric fields (b); overdamped pulsed discharge current curves at different temperatures (c), Wd as a function of time (d) of 0.55BNT-0.45SLT ceramics.
[64] Table 1 Dielectric and ferroelectric properties of (1-x)BNT-xSLT ceramics. x
Ts (°C)
Tm (°C)
m
tan
Temperature range (°C)
Ps (μC/cm2)
Pr (μC/cm2)
Ec (kV/cm)
EF (kV/cm)
0
216
348
3025
0.047
118 - 179
43.2
38.9
75.2
/
0.2 0.3 0.35 0.45
122 85 63 50
301 251 209 /
2341 1850 1653 /
0.041 0.035 0.035 0.022
74 - 271 27 - 341 2 - 273 -22 - 230
36.0 30.0 24.6 19.5
6.6 2.4 0.7 0.4
23.5 12.1 7.3 3.9
57.0 67.2 76.7 /
0.5
4
/
/
0.009
74 - 217
15.3
0.4
2.6
/
Table 2 Comparison of charge-discharge behavior between x = 0.45 ceramic and other lead-free ceramics Composition
CD (A/cm2)
PD (WM/cm3)
WD (J/cm3)
t0.9
E (kV/cm)
Reference
BNT-Sr0.7La0.2TiO3 BT-Bi(Ni2/3Nb1/3)O3 BNT-LiTaO3 (Bi0.32Sr0.42Na0.20)TiO3/MgO Na0.7Bi0.1NbO3 BT-Bi(Zn1/2Sn1/2)O3 NN-Bi(Mg2/3Nb1/3)NbO3 BNT-Sr0.7Bi0.2TiO3-AgNbO3 BKT-La(Mg0.5Ti0.5)O3 BNT-BT-NN/ZnO
1815 738 440 1671 1250 551 370 / / 277.1
182 36.9 22 150 62.5 30.3 18 / / /
2.31 0.54 0.52 1.39 0.56 0.47 / 1.44 0.76 1.17
123 90 100 150 150 160 / 194 200 256
200 100 100 180 100 110 100 120 140 100
This work 43 31 60 59 44 52 6 61 62
BNT: Bi0.5Na0.5TiO3; BT: BaTiO3; BKT: Bi0.5K0.5TiO3; NN: NaNbO3.
[65] 1. SLT is doped into BNT, the Eb is enhanced from 120 kV/cm to 338 kV/cm. 2. 0.55BNT-0.45SLT ceramic exhibits a large Wrec of 4.14 J/cm3 as well as a high ƞ of 92.2%. 3. 0.55BNT-0.45SLT ceramic possesses an excellent stability against testing temperature, frequency and cycle. 4. 0.55BNT-0.45SLT ceramic owns a high power density (182 MW/cm3) and a fast charge-discharge speed (123 ns). [66]
S1385-8947(20)30149-2 https://doi.org/10.1016/j.cej.2020.124158 CEJ 124158
To appear in:
Chemical Engineering Journal
Received Date: Revised Date: Accepted Date:
7 November 2019 7 December 2019 17 January 2020
Please cite this article as: X. Qiao, F. Zhang, D. Wu, B. Chen, X. Zhao, Z. Peng, X. Ren, P. Liang, X. Chao, Z. Yang, Superior comprehensive energy storage properties in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics, Chemical Engineering Journal (2020), doi: https://doi.org/10.1016/j.cej.2020.124158
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2020 Published by Elsevier B.V.
Superior comprehensive energy storage properties in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics
Xiaoshuang Qiaoa, Fudong Zhanga, Di Wua, Bi Chena, Xumei Zhaoa, Zhanhui Penga, Xiaodan Rena, Pengfei Liangb, Xiaolian Chaoa†, Zupei Yanga†
aKey
Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Key Laboratory for
Advanced Energy Devices, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, 710062, Shaanxi, China. bSchool of Physics & Information Technology, Shaanxi Normal University, Xi’an, 710062, Shaanxi, China
† Corresponding
authors shall be addressed at:
Key Laboratory for Macromolecular Science of Shaanxi Province School of Materials Science and Engineering Shaanxi Normal University, Xi'an, 710062, Shaanxi, P.R. China Tel: +86-29-8153-0718; Fax: +86-29-8153-0702 E-mail addresses: [email protected] and [email protected]
Abstract Seeking for high energy storage materials has become an urgent task in the circumstance of energy crisis. In this work, a series of relaxor ferroelectrics (1-x)Bi0.5Na0.5TiO3-xSr0.7La0.2TiO3 ((1-x)BNT-xSLT) with excellent energy storage performance were successfully fabricated. The SLT as a second component was doped into BNT and served three main functions: (1) efficiently decreased the grain size and increased the band gap and thus enhanced the breakdown electric field, (2) drove the ferroelectric phase gradually to a relaxor character, (3) reduced the tolerance factor (t) to defer the electric field of polarization saturation. Eventually, we achieved an impressive recoverable energy storage density (Wrec) of 4.14 J/cm3 and an ultrahigh energy storage efficiency (ƞ) of 92.2% simultaneously at 315 kV/cm in the ceramic of x = 0.45. Furthermore, the sample also exhibited an excellent stability against testing temperature, frequency and cycle, a high power density (182 MW/cm3) and a fast discharge speed (123 ns), all of which are ideal characteristics for high power energy storage devices. Keywords: Bi0.5Na0.5TiO3; Relaxor ferroelectric; Energy storage; Power density 1. Introduction Over the past few years, dielectric capacitors have gained immense attention owing to their high power density, good thermal stability and fast charge/discharge speed [1-3]. In general, the energy storage performance of a specific dielectric material can be derived from its P-E loop [4-6]: Ps
Wrec Edp Pr
(1)
Wrec 100% Wtotal
(2)
where Ps, Pr, E and are the saturation polarization, remanent polarization, applied electric field and energy storage efficiency, respectively [7-9]. According to Equation (1), we concluded that a large recoverable energy storage density (Wrec) depends on a high breakdown electric field (Eb) and a large ΔP = Ps - Pr. As known, dielectrics materials can be classified into four types according to their character of P-E loops [10]: linear dielectrics, ferroelectrics (FE), antiferroelectrics (AFE) and relaxor ferroelectrics (RFE). The low dielectric constant (r) of linear dielectrics limits their energy
storage
density
despite
their
high
Eb.
For
example,
the
(Ca0.5Sr0.5)0.8875La0.075TiO3 ceramic exhibits large Eb (370 kV/cm) but low Wrec (2.07 J/cm3) [11]. Ferroelectrics (such as pure Bi0.5Na0.5TiO3 (BNT), K0.5Na0.5NbO3 (KNN), and BaTiO3 (BT)) show high Pr and low Eb, thus lead to low Wrec and . This limits their practical applications for energy storage devices. Antiferroelectrics are considered as promising energy storage materials because of their large Wrec which originates from their unique double hysteresis loops, but their relative low energy efficiency and poor cycle stability need to be resolved before any practical application. For instance, despite its large Wrec (4.5 J/cm3), Ag0.88Gd0.04NbO3 shows a low of 65% [12]. Relaxor ferroelectrics with a slender P-E loop are deemed to be promising candidates for energy storage materials, owing to their excellent cycle stability, good thermal stability, high power density and fast charge-discharge rate [13,14]. Currently, BNT-based energy storage ceramics have been extensively
investigated, mainly due to their extremely high Ps (> 40 μC/cm2) [15,16]. However, pristine BNT also exhibits a high Pr (38 μC/cm2) at room temperature, which limits its energy storage density [17]. As known, BNT possesses a slim P-E loop and is considered as a relaxor ferroelectric between 200 °C (Ts) and 320 °C (Curie temperature, Tm). Therefore, by decreasing the Ts of BNT below room temperature, its Pr can be reduced and Wrec can be improved. For the sake of decreasing the Pr and improving the Eb synchronously, various additives were added into BNT. Zhang et al. reported that a large Wrec of 2.35 J/cm3 was achieved in SnO2 doped BNT-SrTiO3 ceramics
[18];
Yang
et
al.
studied
the
film
of
Mn-doped
(1-x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xSrTiO3 and obtained an ultrahigh Wrec of 76.1 J/cm3 [19]; Wu et al. prepared 0.96(0.65BNT-0.35Sr0.85Bi0.1TiO3)-0.04NaNbO3 ceramics with a Wrec of 3.08 J/cm3 [20]. According to the above reports, it can be found that the cubic-structured SrTiO3 (ST) plays an important role in improving the Wrec of BNT-based system. This is because SrTiO3 owns a large Eb (200 kV/cm) and a low Curie temperature (Tm = -250 °C). In our previous study, we doped Bi3+ at Sr2+ site in BNT-ST ceramics (expressed as (1-x)BNT-xSBT), and obtained a slim P-E loop with a higher Ps. However, the breakdown field Eb is still quite low and needs to be improved [21]. In this study, we introduced La3+ into Sr2+ site of BNT-ST ceramics, since it was reported that La3+ doping is beneficial of decreasing the grain size and delaying the electric field of polarization saturation in BNT-based ceramics [22,23]. The effect of SLT doping on the improved energy storage properties for BNT was studied in detail, as schemed in Fig.1.
2. Experimental Ceramics with the nominal compositions of (1-x)Bi0.5Na0.5TiO3-xSr0.7La0.2TiO3 (abbreviated as (1-x)BNT-xSLT, x = 0, 0.2, 0.3, 0.35, 0.45 and 0.5) were synthesized via a standard mixed oxide method. The raw materials of TiO2 (>98.0%), Bi2O3 (>98.9%), Na2CO3 (>99.8%), SrCO3 (>99.0%) and La2O3 (>99.99%) were selected as the raw materials and ball-milled for 24 h, after dried, calcined the different components of powder at 850 °C for 3 hours. Finally, pressed the powders into pellets and then sintered at 1150-1200 °C for 3 h. The Archimedes drainage method was used to determine the mass densities of the ceramics. The ceramics’ crystal structures were investigated by a X-ray diffraction instrument (Rigaku, Japan, Cu K) and a transmission electron microscopy (HR-TEM, JEM-2100, Japan). All the ceramics were polished and thermal etched at 1050 °C for 1 h prior to the observation by a scanning electron microscope (SU3500). The dielectric constant and dielectric loss were recorded by a Agilent E4980A instrument. The samples for measuring energy storage properties were polished to a thickness of ~ 0.2 mm, and both sides were covered by gold electrodes with a diameter of 2 mm. P-E loops of the ceramics were obtained using Radiant P-PM2. A charge-discharge apparatus (CFD-001, Gogo Instruments Technology, China) was employed to estimate the charge-discharge behaviour of the samples. 3. Results and discussion Fig. 2(a) shows the XRD patterns of (1-x)BNT-xSLT ceramics. It is clear that all ceramics exhibit the perovskite structure, suggesting that SLT has completely
dissolved into the BNT host lattice. For pure BNT, the peaks near 40 ° correspond to (003) and (021). With an increase in the SLT content, these peaks become more symmetry and merge into one single peak (111), suggesting the perovskite structure gradually changes from the rhombohedral phase (R3c) to the pseudocubic phase (Pc) [24]. Fig. 2(b) gives the enlarged XRD patterns from 38° to 48°. It is seen that the (111) and (200) peaks gradually move to lower angles as the SLT content increases, implying a lattice expansion due to the replacement of Na+ (139 pm) and Bi3+ (138 pm) ions by larger Sr2+ (144 pm) ions [25]. Fig. 2(c) shows the bright-field TEM image and selected area electron diffraction (SAED) spot for x = 0.45 ceramic. The weak super-lattice reflections of the 1/2{ooo} spots (marked by an arrow) indicate the presence of the polar R3c phase along with the pseudocubic lattice, which is contributes to induce high polarization upon applied electric fields [20,26]. According to the energy dispersive X-ray (EDX) mapping in Fig. 2 (d), it can be found that Bi, Na, Sr, La, Ti and O are all uniformly distributed in the x = 0.45 ceramic, this suggests that SLT has well dissolved into BNT lattice and formed a homogeneous solid solution, which is consistent with the XRD results. The thermally etched (1-x)BNT-xSLT ceramics are depicted in Fig. 3(a-f). All samples exhibit clear grain boundaries, dense microstructures and minor pores. With increasing SLT content, the relative density (r) of the ceramics increases gradually, while the average grain size decreases significantly, suggesting that SLT alloying not only improves the density but also prevents the grain growth in BNT ceramics [27]. It is well-known that high r and small grain size are beneficial for improving
breakdown electric field. The reduction of grain size can be explained as follows. First, the smaller ions of Na+ (1.39 Å) and Bi3+ (1.38 Å) are replaced by larger ions of Sr2+ (1.44 Å), which increases the lattice strain energy (ΔGstrain), thus the grain boundary mobility is inhibited [28]. Second, the contents of volatile Na+ and Bi3+ decrease gradually with an increase in the SLT content, thus the concentration of oxygen vacancy is reduced, which restrains the grain growth [29]. The breakdown electric field is not only affected by extrinsic factors such as the porosity and grain size, but also by intrinsic factors such as the band gap (Eg) and dielectric constant. Eg is the energy required by electrons to jump from the top of the valence band to the bottom of the conduction band, which can be calculated by the Tauc equation:
h 2 A(h E g )
(3)
where hv, A and α are photon energy, a constant and absorption coefficient, respectively
[8].
The
ultraviolet-visible
(UV-Vis)
absorbance
spectra
of
(1-x)BNT-xSLT ceramics are shown in Fig. 4(a). With an increase in the SLT content, the Eg increases gradually, and samples of x = 0, 0.2, 0.3 and 0.45 display an Eg of 3.07, 3.09, 3.12 and 3.17 eV, respectively. Fig. 4(c) shows the complex impedance plots of (1-x)BNT-xSLT ceramics. The ceramcs’ resistivity becomes larger as the SLT content increases, which can be determined from the intersection of the x-axis with the semicircular arc at low-frequency. The activation energy of the ceramics are calculated using the Arrhenius formula and shown in Fig. 4(d). It can be seen that the activation energy increases from 0.74 eV for x =0 to 0.97 eV for x = 0.45, suggesting
that the oxygen vacancy concentration decreases as the SLT content increases [6]. To sum up, the higher band gap, larger resistivity and lower oxygen vacancy concentration are beneficial for improving the breakdown electric field of (1-x)BNT-xSLT ceramics [11]. The dielectric constant (εr) and loss tangent (tanδ) of (1-x)BNT-xSLT ceramics as the function of temperature are displayed in Fig. 5(a). There are two dielectric peaks exist in the εr-T curves (Ts and Tm). Ts is originated from the thermal evolution of discrete polar nanoregions (PNRs), and the other anomaly Tm is caused by the transition of rhombohedral PNRs to tetragonal PNRs [14]. The values of Ts, Tm and εm (εr corresponding to Tm) for (1-x)BNT-xSLT samples are shown in Table 1, and exhibit the same decreasing tendency with increasing of SLT. Furthermore, a widened dielectric constant platform can be found between Ts and Tm as the SLT content increases. SLT doping into BNT induced the random electric fields (RFS) by the increased disorder degree and ion charge fluctuation at A-site. Since the RFs can enhance the relaxor behavior of ferroelectrics, the two dielectric peaks of the ceramics gradually weakened and widened, the εm notably decreased along with the εs (εr corresponding to Ts) changed slightly, resulting in a good temperature stability of the dielectric constant. Similar phenomena have been observed in other BNT-based ceramics [30-32]. The rate of change of dielectric constant (ε/ε150°C, ε = εr-ε150°C) as a function of temperature of the ceramics is displayed in Fig. 5(b), it can be seen that the samples of 0.3 ≤ x ≤ 0.45 exhibit excellent temperature stability according to the standard of variation of dielectric constant being less than ± 15%. The specific
temperature ranges of (1-x)BNT-xSLT ceramics are shown in Table 1. Of particular important is that all ceramics put up lower tanδ (< 0.07) between -150 °C - 350 °C. The values of tanδ at room temperature for the samples are shown in Table 1, and the decreased tanδ reduces the amount of heat, resulting in large breakdown electric field [33]. The ferroelectric properties of (1-x)BNT-xSLT ceramics were tested at 120 kV/cm and 10 Hz, and the results are displayed in Fig 4(c-d). Pristine BNT is identified as a typical ferroelectric with a saturated hysteresis loop, and two current peaks can be observed in the I-E curve which corresponds to the coercive field (Ec) [34]. With the increase of SLT, the P-E loops become thinner and nearly linear, suggesting the long-range ordered ferroelectric domains are broken and the relaxation behavior gets enhanced [35]. The relevant values of Ps and Pr are exhibited in Table 1. Four current peaks start to emerge (denoted as ±EF and ±ER) in the I-V curves (x ≥ 0.2), implying the reversible phase transition of RFE and FE exists in these samples [16]. The intensity of current peaks becomes weaker and eventually obscure as the SLT content increases; meanwhile, the electric field becomes larger for the phase transition of EF (shown in Table 1), implying an increase of RFE phase [22], which is conducive to delay the electric field of polarization saturation [15]. The aforementioned results can probably be attributed to the decrement of tolerance factor ( t (rA rO ) / 2 (rB rO ) ), since SLT has a smaller t of 0.945 than the 0.982 for BNT. The ceramics (0.2 ≤ x ≤ 0.5) were tested from 100 kV/cm to their breakdown electric fields, and the results are given in Fig. 6(a). With increasing SLT content, Eb
is improved gradually from 151 to 180, 228, 315 and 338 kV/cm for x = 0.2, x = 0.3, x = 0.35, x = 0.45 and x = 0.5, respectively, the increased Eb can be ascribed to the decreased grain size and dielectric loss. Fig. 6(b) shows the dependence of P on applied electric fields for different ceramics. Notably, the ceramic of x = 0.45 exhibits the largest P and highest Eb synchronously, which are two critical parameters to achieve a large Wrec. Compared to other samples, the sample of x = 0.45 exhibits a large Wrec of 4.14 J/cm3 and a high of 92.2%, as shown in Fig. 6(c). The energy storage properties under different electric fields of x = 0.45 ceramic are displayed in Fig. 6(d), which exhibits that Wrec increases obviously from 0.79 to 4.14 J/cm3 as the electric field increases from 100 to 315 kV/cm; the ƞ decreases slightly from 93.4% to 92.2%, suggesting the good electric field stability of . Figure 5(e) displays the energy storage properties of x = 0.45 sample and other BNT-based ceramics [13,14,16,18,20,24,32,36-42]. We found that the Wrec of BNT-based ceramics are mostly less than 3.5 J/cm3. However, in this work, the Wrec reaches to 4.14 J/cm3, and the result can be attributed to the large P and large Eb of the x = 0.45 ceramic. Figure 5(f) displays a schemed comparison of Wrec and ƞ between our 0.55BNT-0.45SLT sample and other typical lead-free ceramics in literature [11,12,14,20,24,27,36,43-56]. It is well known that the lead-free energy storage ceramics can be divided into BaTiO3-based (BT-), Bi0.5Na0.5TiO3-based (BNT-), K0.5Na0.5NbO3-based (KNN-), AgNbO3-based (AN-), NaNbO3-based (NN-), BiFeO3-based (BF-) and SrTiO3-based (ST-) [57]. Among of them, AN- and KNN- based ceramics exhibit relatively larger Wrec ~ 4 J/cm3; however, their ƞ isn’t high enough for practical application. For BT-
and ST- based ceramics, high ƞ is assured but low Wrec stands as the bottleneck. BNTand BF- based ceramics always exhibit large P because of the hybridization between Bi 6p and O 2p orbitals [4], however, the relatively lower Eb inhibits the realization of large Wrec. In this work, we improved the Eb in (1-x)BNT-xSLT to 315 kV/cm for the specimen of x = 0.45, and realized a large Wrec of 4.14 J/cm3 and a high ƞ of 92% simultaneously. For practical application, the frequency stability and cycle stability are also two very important properties, besides the large Wrec and high η. Fig 6(a) exhibits the frequency dependent P-E loops of the x = 0.45 sample, measured from 5 to 500 Hz under 150 kV/cm, and Fig. 7(b) summarized the energy storage properties. It is seen that the value of Wrec decreases from 1.62 gradually to 1.33 J/cm3 while ƞ varies within only 0.48% as frequency increases from 5 to 500 Hz, suggesting that the sample of x = 0.45 possesses good frequency stability. The P-E loops are not sensitive to frequency can be attributed to the PNRs, due to the polarization response process is dominated by the growth and orientation of PNRs in response to electric fields [15,32]. Fig. 7(c) exhibits the P-E loops from 1 to 105 cycles. As seen, the P-E loops are almost unaffected with cycle number increases, Ps decreases gradually but negligibly from 23.65 to 23.62 µC/cm2, Wrec and ƞ vary a little within 2.8% and 1.2%, respectively (as shown in Fig. 7(d)). These results suggest that the ceramic of x = 0.45 has an excellent cycle stability, which can be attributed to the high quality ceramic with suitable grain size, little pores, highly dynamic PNRs and little defects [43,58].
To analyze the actual charging-discharging capacity of x = 0.45 ceramics, the undamped and overdamped discharge current curves are tested and displayed in Fig. 8. According to Fig. 8(a), we can see that the current peaks increase obviously with the increment of electric field, and the current density (CD) and power density (PD) can be calculated from the curves: CD = Imax/S
(4)
PD = EImax/S
(5)
where S and E represent the electrode area and electric field, respectively [59], and the results are shown in Fig. 8(b). CD and PD exhibit the same evolving tendency, i.e., increase with electric field and reach 1815 A/cm2 and 182 MW/cm3 under 200 kV/cm, respectively. The overdamped discharge current curves at different temperatures and a fixed electric field of 200 kV/cm are shown in Fig. 8(c). The discharge energy density (WD) can be obtained by the following formula: WD = Ri(t)2dt/V
(6)
where V represents the sample volume, load resistance (R) is 300 Ω, and the results are shown in Fig. 8(d)[37]. With increasing of temperature, it can be found that the Wd decreases slightly from 2.31 J/cm3 to 2.08 J/cm3, implying good temperature stability exists in the sample of x = 0.45, besides, the same sample also shows a fast charge-discharge speed t0.9 of 123 ns. Compared to other lead-free ceramics, the sample of x = 0.45 exhibits excellent charge-discharge behavior (Table 2) [6,31,43,44,52,59-62], suggesting its high potential in pulsed power systems application [63].
4. Conclusions In summary, (1-x)BNT-xSLT relaxor ferroelectric ceramics were prepared through a solid-state reaction method. With increasing SLT content, the crystal structure transforms from a rhombohedral phase to a weakly polarized pseudo-cubic phase, the relaxation behavior is enhanced, and the Eb improved from 120 kV/cm for x = 0 to 338 kV/cm for x = 0.5. Furthermore, the electric field of polarization saturation is deferred as the concentration of SLT increase. Ultimately, the sample of x = 0.45 possesses a large Wrec of 4.14 J/cm3 and a high of 92.2%. Moreover, a splendid frequency stability, an excellent fatigue resistance, a large current density (1815 A/cm2) and a high power density (182 MW/cm3) are also obtained in the same sample, enabling the ceramic of 0.55BNT-0.45SLT a hopeful alternative for application in pulse power devices. Acknowledgements This work was supported by the National Science Foundation of China (Grant Nos. 51572163, 51577111 and 51872177), and the Fundamental Research Funds for the Central Universities (Program Nos. GK201802007 and 2018CBLZ007). Conflicts of interest There are no conflicts to declare. References [1] G. Wang, J.L. Li, X. Zhang, Z.M. Fan, F. Yang, A. Feteira, D. Zhou, D.C. Sinclair, T. Ma, X.L. Tan, D.W. Wang, L.M. Reaney, Ultrahigh energy storage density lead-free multilayers by controlled electrical homogeneity. Energy Environ. Sci. 12 (2019) 582-588.
[2] H.S. Wang, Y.C. Liu, T.Q. Yang and S.J. Zhang, Ultrahigh energy-storage density in antiferroelectric ceramics with field-induced multiphase transitions. Adv. Funct. Mater. 29 (2019) 1807321. [3] Z.T. Yang, F. Gao, H.L. Du, L. Jin, L.L. Yan, Q.Y. Hu, Y. Yu, S.B. Qu, X.Y. Wei, Z. Xu and Y.J. Wang, Grain size engineered lead-free ceramics with both large energy storage density and ultrahigh mechanical properties, Nano Energy 58 (2019) 768-777. [4] D.W. Wang, Z.M. Fan, D. Zhou, A. Khesro, S. Murakami, A. Feteira, Q.L. Zhao, X.L. Tan, L.M. Reaney, Bismuth ferrite-based lead-free ceramics and multilayers with high recoverable energy density, J. Mater. Chem. A 6 (2018) 4133-4144. [5] Z.T. Yang, H.L. Du, S.B. Qu, Y.D. Hou, H. Ma, J.F. Wang, J. Wang, X.Y. Wei, Z. Xu, Significantly enhanced recoverable energy storage density in potassium-sodium niobate-based lead free ceramics, J. Mater. Chem. A 4 (2016) 13778-13785. [6] X.S. Qiao, D. Wu, F.D. Zhang, B. Chen, X.D. Ren, P.F. Liang, H.L. Du, X.L. Chao, Z.P. Yang, Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic with large energy density and high efficiency under a moderate electric field, J. Mater. Chem. C 7 (2019) 10514-10520. [7] Z.T. Yang, H.L. Du, L. Jin, Q.Y. Hu, H. Wang, Y.F. Li, J.F. Wang, F. Gao, S.B. Qu, Realizing high comprehensive energy storage performance in lead-free bulk ceramics via designing an unmatched temperature range, J. Mater. Chem. A DOI: 10.1039/c9ta11314b. [8] Q.Z. Chai, D. Yang, X.M. Zhao, X.L. Chao, Z.P. Yang, Lead-free (K,Na)NbO3-based ceramics with high optical transparency and large energy storage ability, J. Am. Ceram. Soc. 101 (2018) 2321-2329. [9] Y. Lin, D. Li, M. Zhang, S. Zhan, Y. Yang, H. Yang, Q. Yuan, Excellent Energy-Storage Properties Achieved in BaTiO3-based lead-free relaxor ferroelectric ceramics via domain engineering on the nanoscale, ACS Appl. Mater. Interfaces 11 (2019) 36824-36830.
[10]T.Q. Shao, H.L. Du, H. Ma, S.B. Qu, J. Wang, J.F. Wang, X.Y. Wei, Z. Xu, Potassium-sodium niobate based lead-free ceramics: novel electrical energy storage materials, J. Mater. Chem. A 5 (2017) 554-563. [11]W. Wang, Y.P. Pu, X. Guo, T. Ouyang, Y. Shi, M.D. Yang, J.W. Li, R.K. Shi, G. Liu, Enhanced energy storage properties of lead-free (Ca0.5Sr0.5)1-1.5xLaxTiO3 linear dielectric ceramics within a wide temperature range, Ceram. Int. 45 (2019) 14684-14690. [12]S. Li, H.C. Nie, G.S. Wang, C.H. Xu, N.T. Liu, M.X. Zhou, F. Cao, X.L. Dong, Significantly enhanced energy storage performance of rare-earth-modified silver niobate lead-free antiferroelectric ceramics via local chemical pressure tailoring, J. Mater. Chem. C 7 (2019) 1551-1560. [13]P. Shi, L.G. Zhu, W.W. Gao, Z.H. Yu, X.J. Lou, X.J. Wang, Z.M. Yang, S. Yang, Large
energy
storage
properties
of
lead-free
(1-x)(0.72Bi0.5Na0.5TiO3-0.28SrTiO3)-xBiAlO3 ceramics at broad temperature range, J. Alloys Compd. 784 (2019) 788-793. [14]Z.B. Pan, D. Hu, Y. Zhang, J.J. Liu, B. Shen, J.W. Zhai, Achieving high discharge energy density and efficiency with NBT-based ceramics for application in capacitors, J. Mater. Chem. C 7 (2019) 4072-4078. [15]H.
Qi,
R.Z.
Zuo,
Linear-like
lead-free
relaxor
antiferroelectric
(Bi0.5Na0.5)TiO3-NaNbO3 with giant energy-storage density/efficiency and super stability against temperature and frequency, J. Mater. Chem. A 7 (2019) 3971-3978. [16]J. Yin, Y.X. Zhang, X. Lv, J.G. Wu, Ultrahigh energy-storage potential under low electric field in bismuth sodium titanate-based perovskite ferroelectrics, J. Mater. Chem. A 6 (2018) 9823-9832. [17]L. Zhang, X.Y. Pu, M. Chen, S.H. Bai, Y.P. Pu, Influence of BaSnO3 additive on the energy storage properties of Na0.5Bi0.5TiO3-based relaxor ferroelectrics, J. Eur. Ceram. Soc. 38 (2018) 2304-2311. [18]L.Y. Zhang, Z.Y. Wang, Y. Li, P. Chen, J. Cai, Y. Yan, Y.F. Zhou, D.W. Wang, G. Liu, Enhanced energy storage performance in Sn doped Sr0.6(Na0.5Bi0.5)0.4TiO3
lead-free relaxor ferroelectric ceramics, J. Eur. Ceram. Soc. 39 (2019) 3057-3063. [19]C.H. Yang, J. Qian, Y.J. Han, P.P. Lv, S.F. Huang, X. Cheng, ZX. Cheng, Design of an all-inorganic flexible Na0.5Bi0.5TiO3-based film capacitor with giant and stable energy storage performance, J. Mater. Chem. A 7 (2019) 22366-22376. [20]Y.C. Wu, Y.Z. Fan, N.T. Liu, P. Peng, M.X. Zhou, S.G. Yan, F. Cao, X.L. Dong, G.S. Wang, Enhanced energy storage properties in sodium bismuth titanate-based ceramics for dielectric capacitor applications, J. Mater. Chem. C 7 (2019) 6222-6230. [21]X.S. Qiao, D. Wu, F.D. Zhang, M.S. Niu, B. Chen, X.M. Zhao, P.F. Liang, L.L. Wei, X.L. Chao, Z.P. Yang, Enhanced energy density and thermal stability in relaxor ferroelectric Bi0.5Na0.5TiO3-Sr0.7Bi0.2TiO3 ceramics, J. Eur. Ceram. Soc. 39 (2019) 4778-4784. [22]F.F. Li, Y.F. Liu, Y.N. Lyu, Y.H. Qi, Z.L. Yu, C.G. Lu, Huge strain and energy storage density of A-site La3+ donor doped (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics, Ceram. Int. 43 (2017) 106-110. [23]X.M. Zhao, X.M. Chen, H.Y. Ma, H.L. Lian, P. Liu, Microstructure, dielectric and
ferroelectric
properties
of
0.97[(Na0.5Bi0.5)1-1.5xLax]TiO3-0.03BaTiO3
lead-free ceramics, J. Alloys Compd. 630 (2015) 236-243. [24]L.T. Yang, X. Kong, Z.X. Cheng, S.J. Zhang, Ultra-high energy storage performance with mitigated polarization saturation in lead-free relaxors, J. Mater. Chem. A 7 (2019) 8573-8580. [25]R.D. Shannon, Revised effective ionic radii and systematic studies of interatomie distances in halides and chaleogenides, Acta Cryst. A32 (1976) 751-767. [26]J.Y. Wu, A. Mahajan, L. Riekehr, H.F. Zhang, B. Yang, N. Meng, Z. Zhang, H.X. Yan, Perovskite Srx(Bi1-xNa0.97-xLi0.03)0.5TiO3 ceramics with polar nano regions for high power energy storage, Nano Energy 50 (2018) 723-732. [27]Y. Huang, F. Li, H. Hao, F.Q. Xia, H.X. Liu, S.J. Zhang, (Bi0.51Na0.47)TiO3 based lead free ceramics with high energy density and efficiency, Journal of Materiomics 5 (2019) 385-393.
[28]J. Boonlakhorn, P. Thongbai, B. Putasaeng, T. Yamwong, S. Maensiri, Very high-performance dielectric properties of Ca1−3x/2YbxCu3Ti4O12 ceramics, J. Alloys Compd. 612 (2014) 103-109. [29]R.A. Malik, A. Hussain, M. Acosta, J. Daniels, H.S. Han, M.H. Kim, J.S. Lee, Thermal-stability of electric field-induced strain and energy storage density in Nb-doped BNKT-ST piezoceramics, J. Eur. Ceram. Soc. 38 (2018) 2511-2519. [30]Y. Yang, H. Wang, L.N. Bi, Q.J. Zheng, G.F. Fan, W.J. Jie, D.M. Lin, High energy storage density and discharging efficiency in La3+/Nb5+-co-substituted (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics, J. Eur. Ceram. Soc. 39 (2019) 3051-3056. [31]L. Zhang, Y.P. Pu, M. Chen, T.C. Wei, X. Peng, Novel Na0.5Bi0.5TiO3 based, lead-free energy storage ceramics with high power and energy density and excellent
high-temperature
stability,
Chem.
Eng.
J.
DOI:
https://doi.org/10.1016/j.cej.2019.123154. [32]W.G. Ma, Y.W. Zhu, M.A. Marwat, P.Y. Fan, B. Xie, D. Salamon, Z.G. Ye, H.B. Zhang, Enhanced energy-storage performance with excellent stability under low electric fields in BNT-ST relaxor ferroelectric ceramics, J. Mater. Chem. C 7 (2019) 281-288. [33]L.T. Yang, X. Kong, F. Li, H. Hao, Z.X. Cheng, H.X. Liu, J.F. Li, S.J. Zhang, Enhanced energy-storage performance with excellent stability under low electric fields in BNT-ST relaxor ferroelectric ceramics, Prog Mater Sci. 102 (2019) 72-108. [34]S. Manotham, P. Butnoi, P. Jaita, N. Kumar, K. Chokethawai, G. Rujijanagul, D.P. Cann, Large electric field-induced strain and large improvement in energy density of bismuth sodium potassium titanate-based piezoelectric ceramics, J. Alloys Compd. 739 (2018) 457-467. [35]S.J. Pang, L. Yang, J.Y. Qin, H. Qin, H. Xie, H. Wang, C.R. Zhou, J.W. Xu, Large electric field-induced strain and large improvement in energy density of bismuth sodium potassium titanate-based piezoelectric ceramics, Appl. Phys. A, 125 (2019) 119.
[36]L. Zhang, Y.P. Pu, M. Chen, Influence of BaZrO3 additive on the energy-storage properties of 0.775Na0.5Bi0.5TiO3-0.225BaSnO3 relaxor ferroelectrics. J. Alloys Compd. 775 (2019) 342-347. [37]L. Zhang, Y.P. Pu, M. Chen, G. Liu, Antiferroelectric-like properties in MgO-modified 0.775Na0.5Bi0.5TiO3-0.225BaSnO3 ceramics for high power energy storage, J. Eur. Ceram. Soc. 38 (2018) 5388-5395. [38]J. Li, F. Li, Z. Xu, S. Zhang, Multilayer lead-free ceramic capacitors with ultrahigh energy density and efficiency, Adv Mater. 30 (2018) 1802155. [39]F. Yan, H. Yang, Y. Lin, T. Wang, Dielectric and ferroelectric properties of SrTiO3-Bi0.5Na0.5TiO3-BaAl0.5Nb0.5O3 lead-free ceramics for high-energy-storage applications, Inorg. Chem. 56 (2017) 13510-13516. [40]B. Hu, H.Q. Fan, L. Ning, Y. Wen, C. Wang, High energy storage performance of [(Bi0.5Na0.5)0.94Ba0.06]0.97La0.03Ti1-x(Al0.5Nb0.5)xO3
ceramics
with
enhanced
dielectric breakdown strength, Ceram. Int. 44 (2018) 15160-15166. [41]C. Wang, F. Yan, H.B. Yang, Y. Lin, T. Wang, Dielectric and ferroelectric properties of SrTiO3-Bi0.54Na0.46TiO3-BaTiO3 lead-free ceramics for high energy storage applications, J. Alloys Compd. 749 (2018) 605-611. [42]Q. Li, W.M. Zhang, C. Wang, L. Ning, C. Wang, Y. Wen, B. Hu, H.Q. Fan, Enhanced
energy-storage
performance
of
(1-x)(0.72Bi0.5Na0.5TiO3-0.28Bi0.2Sr0.7TiO3)-xLa ceramics, J. Alloys Compd. 775 (2019) 116-123. [43]M.X. Zhou, R.H. Liang, Z.Y. Zhou, X.L. Dong, Combining high energy efficiency and fast charge-discharge capability in novel BaTiO3-based relaxor ferroelectric ceramic for energy-storage, Ceram. Int. 45 (2019) 3582-3590. [44]M.X. Zhou, R.H. Liang, Z.Y. Zhou, X.L. Dong, Novel BaTiO3-based lead-free ceramic capacitors featuring high energy storage density, high power density, and excellent stability, J. Mater. Chem. C 6 (2018) 8528-8537. [45]Q.B. Yuan, G. Li, F. Z. Yao, S.D. Cheng, Y.F. Wang, R. Ma, S.B. Mi, M. Gu, K. Wang, J.F. Li, H. Wang, Simultaneously achieved temperature-insensitive high
energy density and efficiency in domain engineered BaTiO3-Bi(Mg0.5Zr0.5)O3 lead-free relaxor ferroelectrics, Nano Energy 52 (2018) 203-210. [46]W.B. Li, D. Zhou, L.X. Pang, R. Xu, H.H. Guo, Novel barium titanate based capacitors with high energy density and fast discharge performance, J. Mater. Chem. A 5 (2017) 19607-19612. [47]Z.N. Yan, D. Zhang, X.F. Zhou, H. Qi, H. Luo, K.C. Zhou, I. Abrahams, H.X. Yan, Silver niobate based lead-free ceramics with high energy storage density, J. Mater. Chem. A 7 (2019) 10702-10711. [48]N.N. Luo, K. Han, F.P. Zhuo, C. Xu, G.Z. Zhang, LJ. Liu, X.Y. Chen, C.Z. Hu, H.F. Zhou, Y.Z. Wei, Aliovalent A-site engineered AgNbO3 lead-free antiferroelectric ceramics toward superior energy storage density, J. Mater. Chem. A 7 (2019) 14118-14128. [49]L. Zhao, Q. Liu, J. Gao, S. Zhang, J. F. Li, Lead-Free Antiferroelectric silver niobate tantalate with high energy storage performance, Adv. Mater. 29 (2017) 1701824. [50]H.G. Yang, H. Qi, R.Z. Zuo, Enhanced breakdown strength and energy storage density in a new BiFeO3 based ternary lead-free relaxor ferroelectric ceramic, J. Eur. Ceram. Soc. 39 (2019) 2673-2679. [51]D.G.
Zheng,
R.Z.
Zuo,
La(Mg1/2Ti1/2)O3-modified
Enhanced
BiFeO3-BaTiO3
energy
storage
lead-free
properties
relaxor
in
ferroelectric
ceramics within a wide temperature range, J. Eur. Ceram. Soc. 37 (2017) 413-418. [52]J.M. Ye, G.S. Wang, M.X. Zhou, N.T. Liu, X.F. Chen, S. Li, F. Cao, X.L. Dong, Excellent comprehensive energy storage properties of novel lead-free NaNbO3-based ceramics for dielectric capacitor applications, J. Mater. Chem. C 7 (2019) 5639-5645. [53]M.X. Zhou, R.H. Liang, Z.Y. Zhou, S.G. Yan, X.L. Dong, Novel sodium niobate-vased lead-free ceramics as new environment-friendly energy storage materials with high energy density, high power density, and excellent stability. ACS Sustain. Chem. Eng. 6 (2018) 12755-12765.
[54]Q. Luo, Z.H. Yao, G.F. Zhang, L. Zhang, J. Xie, H. Hao, M.H. Cao, H.X. Liu, Unfolding dielectric breakdown effects on energy storage performances of modified (Sr0.98Ca0.02)(Ti1-xZrx)O3 ceramics, Int. J. Appl. Ceram. Tec. 15 (2018) 1030-1039. [55]H.B. Yang, F. Yan, Y. Lin, T. Wang, L. He, F. Wang, A lead free relaxation and high energy storage efficiency ceramics for energy storage applications, J. Alloys Compd. 710 (2017) 436-445. [56]H.B. Yang, P.F. Liu, F. Yan, Y. Lin, T. Wang, A novel lead-free ceramic with layered structure for high energy storage applications, J. Alloys Compd. 773 (2019) 244-249. [57]Z.T. Yang, H.L. Du, L. Jin, Q.Y. Hu, S.B. Qu, Z.N. Yang, Y. Yu, X.Y. Wei, Z. Xu, A new family of sodium niobate-based dielectrics for electrical energy storage applications, J. Eur. Ceram. Soc. 39 (2019) 2899-2907. [58]W.Y. Pan, C.F. Yue, O. Tosyali, Fatigue of ferroelectric polarization and the electric field induced strain in lead lanthanum zirconate titanate ceramics, J. Am. Ceram. Soc. 75 (1992) 1534-1540. [59]M.X. Zhou, R.H. Liang, Z.Y. Zhou, X.L. Dong, Superior energy storage properties and excellent stability of novel NaNbO3-based lead-free ceramics with A-site vacancy obtained via a Bi2O3 substitution strategy, J. Mater. Chem. A 6 (2018) 17896-17904. [60]F. Li, X. Hou, J. Wang, H.R. Zeng, B. Shen, J.W. Zhai, Structure-design strategy of 0-3 type (Bi0.32Sr0.42Na0.20)TiO3/MgO composite to boost energy storage density, efficiency and charge-discharge performance, J. Eur. Ceram. Soc. 39 (2019) 2889-2898. [61]F. Li, T. Jiang, J.W. Zhai, B. Shen, H.R. Zeng, Exploring novel bismuth-based materials for energy storage applications, J. Mater. Chem. C 6 (2018) 7976-7981. [62]Y. Yao, Y. Li, N.N. Sun, J.H. Du, X.W. Li, L.W. Zhang, Q.W. Zhang, X.H. Hao, Enhanced
dielectric
and
energy-storage
properties
in
ZnO-doped
0.9(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-0.1NaNbO3 ceramics, Ceram. Int. 44 (2018) 5961-5966.
[63]X.M. Yang, F.P. Zhuo, C.X. Wang, Y. Liu, Z.J. Wang, H. Tailor, C. He, X.F. Long, High energy storage density and ultrafast discharge in lead lutetium niobate based ceramics, J. Mater. Chem. A 7 (2019) 8414-8422.
Fig. 1 Schematic diagram of achieving large Wrec and high simultaneously: Eb is increased by decreasing grain size and increasing band gap; relaxation behavior is enhanced by driving Ts to room temperature; electric field of polarization saturation is delayed by reducing tolerance factor.
Fig. 2 (a) XRD curves of (1-x)BNT-xSLT ceramics, (b) enlarged images of (111) and (200) peaks; (c) bright-field TEM image and SAED spots for region ① , (d) EDX mapping images of 0.55BNT-0.45SLT ceramic.
Fig. 3 SEM images, relative density and grain size distribution of (1-x)BNT-xSLT ceramics: (a) x = 0, (b) x = 0.2, (c) x = 0.3, (d) x = 0.35, (e) x = 0.45, (f) x = 0.5.
Fig. 4 UV-Vis absorbance spectra (a) and (hv)2 vs. hv plots (b) of (1-x)BNT-xSLT ceramics. Complex impedance (c) and activation energy (d) of (1-x)BNT-xSLT ceramics.
Fig. 5 Temperature dependence of dielectric constant and loss tangent at 1 kHz (a), temperature range of ε150°C 15% at 1 kHz (b), P-E loops (c) and I-V curves (d) of (1-x)BNT-xSLT ceramics.
Fig. 6 Unipolar P-E loops at different electric fields (a), variation of P with the electric field (b) and Wrec and ƞ values (c) of (1-x)BNT-xSLT ceramics; ƞ and Wrec values of x = 0.45 ceramic at various electric fields (d). Energy storage properties of x = 0.45 ceramic and previously reported BNT-based ceramics (e), Wrec and ƞ of typical lead-free ceramics (f).
Fig. 7 Frequency and cycle stability of (1-x)BNT-xSLT ceramics at 150 kV/cm.
Fig. 8 Undamped pulsed discharge current curves (a), values of CD and PD at various electric fields (b); overdamped pulsed discharge current curves at different temperatures (c), Wd as a function of time (d) of 0.55BNT-0.45SLT ceramics.
[64] Table 1 Dielectric and ferroelectric properties of (1-x)BNT-xSLT ceramics. x
Ts (°C)
Tm (°C)
m
tan
Temperature range (°C)
Ps (μC/cm2)
Pr (μC/cm2)
Ec (kV/cm)
EF (kV/cm)
0
216
348
3025
0.047
118 - 179
43.2
38.9
75.2
/
0.2 0.3 0.35 0.45
122 85 63 50
301 251 209 /
2341 1850 1653 /
0.041 0.035 0.035 0.022
74 - 271 27 - 341 2 - 273 -22 - 230
36.0 30.0 24.6 19.5
6.6 2.4 0.7 0.4
23.5 12.1 7.3 3.9
57.0 67.2 76.7 /
0.5
4
/
/
0.009
74 - 217
15.3
0.4
2.6
/
Table 2 Comparison of charge-discharge behavior between x = 0.45 ceramic and other lead-free ceramics Composition
CD (A/cm2)
PD (WM/cm3)
WD (J/cm3)
t0.9
E (kV/cm)
Reference
BNT-Sr0.7La0.2TiO3 BT-Bi(Ni2/3Nb1/3)O3 BNT-LiTaO3 (Bi0.32Sr0.42Na0.20)TiO3/MgO Na0.7Bi0.1NbO3 BT-Bi(Zn1/2Sn1/2)O3 NN-Bi(Mg2/3Nb1/3)NbO3 BNT-Sr0.7Bi0.2TiO3-AgNbO3 BKT-La(Mg0.5Ti0.5)O3 BNT-BT-NN/ZnO
1815 738 440 1671 1250 551 370 / / 277.1
182 36.9 22 150 62.5 30.3 18 / / /
2.31 0.54 0.52 1.39 0.56 0.47 / 1.44 0.76 1.17
123 90 100 150 150 160 / 194 200 256
200 100 100 180 100 110 100 120 140 100
This work 43 31 60 59 44 52 6 61 62
BNT: Bi0.5Na0.5TiO3; BT: BaTiO3; BKT: Bi0.5K0.5TiO3; NN: NaNbO3.
[65] 1. SLT is doped into BNT, the Eb is enhanced from 120 kV/cm to 338 kV/cm. 2. 0.55BNT-0.45SLT ceramic exhibits a large Wrec of 4.14 J/cm3 as well as a high ƞ of 92.2%. 3. 0.55BNT-0.45SLT ceramic possesses an excellent stability against testing temperature, frequency and cycle. 4. 0.55BNT-0.45SLT ceramic owns a high power density (182 MW/cm3) and a fast charge-discharge speed (123 ns). [66]