Ultrafast discharge energy storage ceramic for pulse power system and preparation method thereof

Abstract

This invention discloses a Bi0.5Na0.5TiO3-based ceramic and its preparation method that achieve excellent energy storage performance through ergodic relaxation state modulation, belonging to the technical field of lead-free dielectric energy storage ceramic materials. This invention introduces a multi-component relaxation end-member Sr0.7Bi0.2TiO3. 55 Sn0. 45 O3(SBTS) constructs an ergodic relaxation state, effectively decoupling the contradiction between polarization and breakdown, resulting in ultra-high energy storage density, high efficiency, wide temperature and frequency stability, and ultrafast discharge performance. Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics, with the general chemical formula (1-x)BNT-xSBTS solid solution, have the best-performing composition point located at x=0.36. The average grain size of the ceramic is controlled to a uniform scale of 2.07 μm. The ceramic achieves a recoverable energy density of 9.92 J / cm³ and an energy efficiency of 84.1%. Within a wide temperature range of 25–125℃ and a wide frequency range of 5–200 Hz, its discharge time constant is only 23 ns, corresponding to a power density as high as 11.94 MW / cm³. The capacitor of this invention exhibits excellent high-temperature energy storage performance and cycle stability, and is expected to be applied in pulse power systems, advanced power electronic equipment, new energy vehicles, and other fields.

Description

Technical Field

[0001] This invention belongs to the technical field of lead-free dielectric energy storage ceramic materials, specifically relating to a Bi0.5Na0.5TiO3-based ceramic and its preparation method that achieves excellent energy storage performance through ergodic relaxation state modulation. Background Technology

[0002] With the rapid development of pulsed power and advanced power electronics technologies, the requirements for dielectric capacitors are becoming increasingly stringent—they must achieve high energy density and high energy efficiency, maintain stability over a wide temperature range, and have charging and discharging speeds approaching their limits. Among numerous candidate solutions, dielectric ceramic capacitors, with their nanosecond-level charge and discharge response, extremely high power density, and excellent temperature stability, have formed a differentiated advantage that electrochemical batteries and supercapacitors cannot surpass, making them an irreplaceable component in key energy storage systems.

[0003] In the field of lead-free relaxor ferroelectric ceramics, Bi0.5Na0.5TiO3 (BNT)-based materials have long been considered a promising candidate system for energy storage due to their high maximum polarization intensity. However, pure-phase BNTs are not without their drawbacks—in fact, they possess both shortcomings and potential. Their strong long-range ferroelectric ordering characteristics make... P - E The hysteresis loop tends to be square, and the remanent polarization intensity remains high, inevitably leading to high energy loss and low efficiency. Simultaneously, the large grain size results in a non-uniform electric field distribution within the material, significantly weakening the dielectric breakdown strength. Particularly challenging is the deeply ingrained trade-off between recoverable energy density and energy efficiency: improvements in one often come at the expense of the other. This inherent contradiction severely limits the practical deployment of BNT-based ceramics in miniaturized, highly integrated electronic systems.

[0004] To overcome the aforementioned problems, existing research has continuously optimized the performance of BNT-based ceramics through various strategies such as component modification and microstructure control. However, achieving a combination of high recoverable energy density, high energy efficiency, wide-temperature and wide-frequency stability, and ultrafast discharge capability within the same material system remains a formidable scientific challenge. Therefore, how to decouple the inherent conflict between polarization response and breakdown tolerance, and thus develop BNT-based energy storage ceramics with excellent comprehensive performance, has become a core issue urgently needing breakthroughs in the field of dielectric materials research. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-energy-storage-performance Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic and its preparation method, by introducing a multi-component relaxor end-member Sr0.7Bi0.2TiO3. 55 Sn0.45 O3(SBTS) constructs an ergodic relaxation state, effectively decoupling the contradiction between polarization and breakdown, and obtaining ultra-high energy density, high efficiency, wide temperature and frequency stability and ultra-fast discharge performance.

[0006] This invention provides a Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic with high energy storage characteristics, having the general chemical formula (1-x)BNT-xSBTS solid solution, wherein the component with the best performance is located at x=0.36. The average grain size of the ceramic is controlled to a uniform scale of 2.07 μm. The ceramic has a recoverable energy density of 9.92 J / cm³ and an energy efficiency of 84.1%. Within a wide temperature range of 25–125 °C and a wide frequency range of 5–200 Hz, its discharge time constant is only 23 ns, corresponding to a power density as high as 11.94 MW / cm³.

[0007] Specifically, this invention provides a Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic with high energy storage characteristics. Through the synergistic intervention of multi-component compositional engineering, the long-range ferroelectric ordered structure of the matrix is ​​effectively dismantled, inducing the formation of a highly dynamic ergonomic relaxation state characterized by nano-polar microregions (PNRs). This system, through ergonomic relaxation state design, achieves near-zero remanent polarization and fine... P - E The material achieves an ultra-high energy density of 9.92 J / cm³ and a high energy efficiency of 84.1%. Simultaneously, localized lattice distortion induces a significant solid solution dragging effect, suppressing abnormal grain growth and refining the average grain size of the ceramic to a uniform scale of 2.07 μm. The full activation of the solute dragging effect leads to a significant refinement of the grain size, both of which contribute to a highly uniform internal electric field distribution, thereby significantly increasing the dielectric breakdown field. The material exhibits minimal performance degradation across a wide temperature range of 25–125 °C and a wide frequency range of 5–200 Hz, demonstrating excellent environmental stability.

[0008] Compared with the prior art, the technical effects of the present invention are reflected in: (1) performance breakthrough: through ergodic relaxation state design, near-zero remanent polarization and fine texture are obtained. P - E(1) Recycled line, simultaneously achieving an ultra-high energy storage density of 9.92 J / cm³ and a high energy efficiency of 84.1%, solving the problems of high loss and low efficiency of traditional BNT-based ceramics; (2) Structural optimization: The full activation of the solute drag effect brings about a significant refinement of the grain size, which promotes the internal electric field distribution to tend to be highly uniform, thereby significantly increasing the dielectric breakdown field strength. This structural optimization measure effectively decouples the trade-off between polarization response and breakdown tolerance; (3) Environmental adaptability: The material exhibits minimal attenuation of various performance indicators in a wide temperature range of 25–125 ℃ and a wide frequency range of 5–200 Hz, demonstrating strong robustness in extreme service conditions and meeting the requirements for use in extreme conditions; (4) Excellent pulse performance: 23ns ultrafast discharge rate and 11.94 High power density of MW / cm³, suitable for high-speed charging and discharging requirements of pulse power systems; (5) Controllable process: The traditional solid-phase reaction method is adopted, the raw materials are readily available, the process is stable and repeatable, and it is suitable for large-scale production.

[0009] Some of the additional advantages, objectives, and features of this invention will be described in detail below, which will enable those skilled in the art to clearly understand the essence of this invention and guide related research or practice. Please note that the scope of application of this invention is not limited to the specific description above, and the various objectives and advantages that this invention can achieve can be more fully understood based on the detailed description below, including but not limited to the above content. Attached Figure Description

[0010] Figure 1 These are the XRD patterns of ceramics with different components in this invention.

[0011] Figure 2 This is a SEM morphology and EDS elemental distribution diagram of the ceramic surface in this invention.

[0012] Figure 3 This is a diagram showing the ceramic ferroelectric and energy storage performance of the present invention.

[0013] Figure 4 This is a test diagram of the temperature and frequency stability of ceramics in this invention.

[0014] Figure 5 This is a diagram showing the ceramic pulse charge-discharge performance of the present invention. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. By reading this specification, those skilled in the art will easily understand other advantages and functions of the present invention. Furthermore, the details in this specification can be appropriately adjusted or modified according to different viewpoints and applications without departing from the core concept of the present invention.

[0016] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0017] Furthermore, it should be understood that the one or more method steps mentioned in this invention do not exclude the existence of other method steps. Other method steps may be inserted before or after the combined steps, or between the explicitly mentioned steps, unless otherwise stated. Moreover, without substantially altering the technical content, their relative relationships can be adjusted or changed, which still falls within the scope of this invention.

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The present invention uses the traditional mixed oxide method to prepare (1-x)BNT-xSBTS ceramics, and the optimal embodiment is a composition with x=0.36.

[0019] Example 1: Preparation of ceramics with the optimal composition of 0.64BNT-0.36SBTS. Raw material pretreatment: Bi2O3, Na2CO3, TiO2, SrCO3, and SnO2 (purity ≥99.0%) were pre-dried at 80℃ for 8 hours and accurately weighed according to the stoichiometric ratio of 0.64BNT-0.36SBTS; Ball milling and mixing: using anhydrous ethanol as the dispersion medium, the mixture was ball-milled at 300rpm for 24 hours, dried, and then pulverized through a 100-mesh standard sieve; Pre-firing synthesis: the perovskite phase was synthesized by holding at 850℃ for 4 hours, followed by ball milling and sieving to optimize powder dispersibility; Molding: granulation was performed by adding 5wt% PVA aqueous solution, and the mixture was uniaxially pressed at 150MPa to form Φ15mm disc blanks; Debinding: the temperature was increased to 650℃ at 2℃ / min and held for 2 hours to completely remove the binder; Sintering: the mixture was sintered at 1200℃ for 2 hours in a sealed crucible to obtain dense 0.64BNT-0.36SBTS ceramic.

[0020] The optimal ceramic composition exhibits the following properties after testing: a pure perovskite crystal structure with trace amounts of SnO2 as a secondary phase; an average grain size of 2.07 μm; typical ergonomic relaxation characteristics; a flat dielectric temperature spectrum over a wide temperature range; and unipolar properties. P - E The return line is thin. P r ≈0.09μC / cm²; =9.92 J / cm³, =84.1%; stable performance within 25-125℃ and 5-200Hz; =23ns, PD=11.94 MW / cm³.

[0021] In summary, this invention, through synergistic design of composition and structure, successfully overcomes the performance bottleneck of BNT-based ceramics, preparing a lead-free relaxor ferroelectric ceramic that combines high energy density, high efficiency, wide temperature and frequency stability, and ultrafast discharge. This provides a core dielectric energy storage material for next-generation pulse power and power electronics systems. Furthermore, the traditional solid-state reaction method ensures readily available raw materials, stable processes, and good reproducibility, making it suitable for large-scale production. This ceramic is applicable to the fabrication of dielectric energy storage devices in pulse power systems, advanced power electronic equipment, and new energy vehicles, significantly improving the performance and reliability of electronic devices and driving the development of lead-free dielectric energy storage ceramic materials technology. It possesses broad application prospects and industrialization value.

Claims

1. This invention provides a high-energy-storage-performance Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic, characterized in that, The ceramic belongs to the (1-x)Bi0.5Na0.5TiO3-xSr0.7Bi0.2TiO. 55 Sn0. 45 The O3 solid solution system, with x = 0.36, exhibits ergodic relaxation ceramic characteristics and nanoscale polar regions. The average grain size is measured to be 2.07 μm, the recoverable energy density reaches 9.92 J / cm³, and the energy efficiency is 84.1%. It demonstrates stable performance within a temperature range of 25-125℃ and a frequency range of 5-200 Hz. The discharge time is measured to be 23 ns, and the power density is [not specified in the original text]. P D It reached 11.94 MW / cm³.

2. The high energy storage performance Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic according to claim 1 is characterized by an ABO3-type perovskite structure, with the appearance of a SnO2 second phase as the SBTS doping amount increases, the interplanar spacing increases, the cell volume expands, and the tetragonal distortion enhances the structural phase transition characteristics.

3. The high-energy-storage-performance Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic according to claim 1, is characterized by the ceramic possessing a wide-temperature-range stable dielectric plateau, ultra-low dielectric loss, and exhibiting typical ergonomic relaxor ferroelectric characteristics. P - E The hysteresis loop is thin, and the residual polarization intensity Pr is close to 0.

4. A method for preparing the high energy storage performance Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic as described in claim 1, wherein the raw material pretreatment includes the following steps: (1) Raw material pretreatment: Bi2O3, Na2CO3, TiO2, SrCO3 and SnO2 analytical grade raw materials were pre-dried at 80℃ and weighed according to stoichiometric ratio; (2) Ball milling and mixing: The raw materials were ball milled at 300 rpm for 24 hours with anhydrous ethanol as medium, dried and pulverized through a 100-mesh sieve; (3) Pre-sintering synthesis: Perovskite phase powder was synthesized by heat treatment at 850℃ for 4 hours, and then ball milled and sieved again; (4) Molding treatment: 5% polyvinyl alcohol aqueous solution binder was added to the powder and uniaxially pressed into a disc-shaped sample at 150 MPa; (5) Adhesive removal treatment: The binder was removed by heating to 650℃ at 2℃ / min and holding for 2 hours; (6) Sintering densification: The sample was placed in a sealed crucible and sintered at 1150-1250℃ for 2 hours to obtain a dense ceramic body.

5. The preparation method according to claim 4, characterized in that, In step (1), the purity of the raw material is ≥99.0%, and pre-drying is used to avoid weighing errors caused by moisture absorption.

6. The preparation method according to claim 4, characterized in that, In step (3), pre-calcination is used to form a pure perovskite phase, and secondary ball milling optimizes the particle size distribution of the powder.

7. The preparation method according to claim 4, characterized in that, In step (5), slow heating and glue removal are used to prevent the sample from cracking and to ensure the integrity of the blank.

8. The preparation method according to claim 4, characterized in that, In step (6), sealing and sintering inhibits the high-temperature volatilization of Bi and Na elements, ensuring the density and compositional uniformity of the ceramic.

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