Enhanced Energy Storage Performance in La-Doped CaBi₄Ti₄O₁₅ Films Through the Formation of a Weakly Coupled Relaxor

Quanlong Liu^{1

2}, Lei Zhang^{1

2}, Jun Ouyang³, Yan Liu^{1

2}, Zhehong Tang^{1

2}, Jieyu Chen^{1

2}, Fei Guo^{1

2}, Yunpeng Zhou^{1

2}

Affiliations

¹ College of Science, Inner Mongolia University of Technology, Hohhot 010051, China.
² Discharge Plasma and Functional Materials Application Laboratory, Inner Mongolia University of Technology, Hohhot 010051, China.
³ Institute of Advanced Energy Materials and Chemistry, School of Chemistry and Chemical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.

PMID: 39728534
PMCID: PMC11728794
DOI: 10.3390/nano14241998

Enhanced Energy Storage Performance in La-Doped CaBi₄Ti₄O₁₅ Films Through the Formation of a Weakly Coupled Relaxor

Quanlong Liu et al. Nanomaterials (Basel). 2024.

. 2024 Dec 13;14(24):1998.

doi: 10.3390/nano14241998.

Authors

Quanlong Liu^{1

2}, Lei Zhang^{1

2}, Jun Ouyang³, Yan Liu^{1

2}, Zhehong Tang^{1

2}, Jieyu Chen^{1

2}, Fei Guo^{1

2}, Yunpeng Zhou^{1

2}

Affiliations

¹ College of Science, Inner Mongolia University of Technology, Hohhot 010051, China.
² Discharge Plasma and Functional Materials Application Laboratory, Inner Mongolia University of Technology, Hohhot 010051, China.
³ Institute of Advanced Energy Materials and Chemistry, School of Chemistry and Chemical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.

PMID: 39728534
PMCID: PMC11728794
DOI: 10.3390/nano14241998

Abstract

Relaxor ferroelectric film capacitors exhibit high power density with ultra-fast charge and discharge rates, making them highly advantageous for consumer electronics and advanced pulse power supplies. The Aurivillius-phase bismuth layered ferroelectric films can effectively achieve a high breakdown electric field due to their unique insulating layer ((Bi₂O₂)²⁺ layer)). However, designing and fabricating Aurivillius-phase bismuth layer relaxor ferroelectric films with optimal energy storage characteristics is challenging due to their inherently stable ferroelectric properties. In this work, lead-free CaBi_4-xLa_xTi₄O₁₅ films were synthesized using the sol-gel technique and a weakly coupled relaxor design. On one hand, the introduction of La³⁺ ions weaken the dipole-dipole interactions, thereby enhancing the relaxor behavior. Alternatively, the expansion of grain size is restricted to enhance the number of grain boundaries, which possess improved insulating properties. This leads to a higher breakdown electric field. The results indicate that CaBi_4-xLa_xTi₄O₁₅ (x = 1.0) films exhibit excellent recoverable energy storage density (70 J/cm³) and high energy efficiency (73%). Moreover, the film exhibited good temperature stability and frequency stability. This study not only identifies a promising material for dielectric film capacitors but also demonstrates that the energy storage capabilities of Aurivillius-phase bismuth layer ferroelectric films can be effectively modulated through a design incorporating weakly coupled relaxor characteristics.

Keywords: PNRs; breakdown strength; energy storage; weakly coupled relaxor.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

**Figure 1**
(a) The crystal structure diagram of CaBi₄Ti₄O₁₅ film. (b) XRD patterns of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films. (c) Raman spectra of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films.

**Figure 2**
(a₁–d₁) Surface SEM images of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films, and the inset shows the corresponding cross-sectional SEM images of CBLT-0.0, CBLT-0.8, CBLT-1.00, and CBLT-1.2 films, respectively. (a₂–a₅) EDS mapping images of specific elements (Ca, Bi, Ti, and O) of CBLT-0.0 film. (b₂–b₆) EDS mapping images of specific elements (Ca, Bi, La, Ti, and O) of CBLT-0.8 film. (c₂–c₆) EDS mapping images of specific elements (Ca, Bi, La, Ti, and O) of CBLT-1.0 film. (d₂–d₆) EDS mapping images of specific elements (Ca, Bi, La, Ti, and O) of CBLT-1.2 film.

**Figure 3**
(a) Ca 2p, (b) Bi 4f, (c) Ti 2p and (d) O 1s XPS spectra of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films.

**Figure 4**
Temperature-dependent ε_r and tanδ measured at different frequencies of (a) CBLT-0.0, (b) CBLT-0.8, (c) CBLT-1.0, and (d) CBLT-1.2 films. The inset displays fitted curves that correspond to the modified Curie–Weiss law.

**Figure 5**
Phase PFM images, the evolution behavior of domains under ± 50 V and after a duration of 15 min for (a–c) CBLT-0.0 film and (d–f) CBLT-1.0 film.

**Figure 6**
(a) *P-E* loops of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films at 1040 kV/cm. (b) variations in the P_max and P_r values of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films at 1040 kV/cm. (c) *P-E* loops of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films were measured under E_b. (d) The Weibull distribution of E_b for CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films. (e) *J–E* curves of leakage current for CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films. (f) the W_rec and ƞ of CBLT-x (x = 0.0, 0.8, 1.0, and 1.2) films. (g) W_rec/E comparison of CBLT-1.0 film with other energy storage film systems. (h) The discharge current curve of CBLT-1.0 film under ambient conditions. (i) The W_dis of CBLT-1.0 film at different electric fields.

**Figure 7**
(a) Temperature-dependent *P-E* loops of CBLT-1.0 film at 1500 kV/cm. (b) The values of W_rec and ƞ were measured at various measured temperatures. (c) The variation of W_rec/E in the CBLT-1.0 film at different temperatures. (d) Frequency-dependent *P-E* loops of CBLT-1.0 film at 1500 kV/cm. (e) The values of W_rec and ƞ were measured at various measured frequencies. (f) The variation of W_rec/E in the CBLT-1.0 film at different frequencies.

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References

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Enhanced Energy Storage Performance in La-Doped CaBi₄Ti₄O₁₅ Films Through the Formation of a Weakly Coupled Relaxor

Affiliations

Enhanced Energy Storage Performance in La-Doped CaBi₄Ti₄O₁₅ Films Through the Formation of a Weakly Coupled Relaxor

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

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