A lead-free ultra-thin ceramic material with high energy storage performance and its preparation method

Abstract

The present invention discloses a lead-free ultra-thin ceramic material with high energy storage performance and a preparation method thereof. The chemical formula of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti (1‑x) Ta x O3, where x = 0.03 to 0.07; by selecting Bi with high polarization strength 0.39 Na 0.36 Sr 0.25 TiO3 ceramics, introducing high-valence Ta into the B site 5+ On the one hand, it reduces the effect of Ti element valence on leakage current and withstand voltage strength, and on the other hand, it forms a low dielectric constant Sr 0.5 BiTaTiO 6.5 phase; and through the solid phase reaction method and cast molding process, a lead-free ultra-thin ceramic material with a thickness of less than 20μm is prepared. The ceramic material has the characteristics of thin thickness, good density and flatness, low dielectric loss, high breakdown electric field strength, excellent energy storage performance, simple preparation method, and does not contain lead elements, which meets the needs of miniaturization and green development of electronic components.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage ceramic media, and in particular to a lead-free ultra-thin ceramic material with high energy storage performance and a preparation method thereof. Background Art

[0002] With the global energy crisis and environmental pollution becoming increasingly prominent, new energy storage technologies that are efficient, environmentally friendly, and sustainable are gaining increasing attention. Compared to batteries and electrochemical capacitors, dielectric capacitors offer fast charge and discharge speeds, high power density, and safety and reliability, attracting widespread attention in pulsed power systems. Lead-free ceramic dielectric capacitors, in particular, can operate for extended periods in extreme environments such as high temperature and high voltage, and have become a research hotspot. However, existing lead-free ceramic dielectric capacitors struggle to achieve significant increases in both polarization strength and breakdown electric field strength, resulting in generally low energy storage density and efficiency. Furthermore, current research on lead-free energy storage ceramics generally utilizes traditional granulation and pressing processes. Sintered ceramic samples are typically thicker than 500μm, requiring thinning to less than 200μm for energy storage performance testing. This thinning process often results in defects such as scratches and cracks, significantly limiting improvements in breakdown electric field strength and energy storage performance, making significant improvements in the energy storage performance of lead-free energy storage ceramics difficult to achieve.

[0003] At present, the methods for improving the energy storage performance of lead-free ceramic dielectrics mainly focus on equivalent element doping, grain size and domain structure regulation, construction of core-shell structure and layered heterostructure, etc. For example, Yang et al. (L. Yang, X. Kong, Z. Cheng, S. Zhang, Ultra-high energy storage performance with mitigated polarization saturation in lead-free relaxors. J. Mater. Chem. A 7, 8573-8580 (2019)) from the University of Wollongong, Australia, have reported on the development of a new energy storage performance with mitigated polarization saturation in lead-free relaxors. 0.5 Na 0.5 A certain amount of Sn is introduced into the TiO3-SrTiO3 system 4+ , due to Sn 4+ and Ti 4+ Different electronic configurations slow down the preparation of (Na 0.25 Bi 0.25 Sr 0.5 The phenomenon of premature saturation of the polarization intensity of )(Ti,Sn)O3 ceramics was studied, and 3.40J / cm 3The effective energy storage density and energy storage efficiency of 90% are achieved. 0.32 Sr 0.42 Na 0.20 )TiO3 / MgO composite to boost energy storage density, efficiency and charge-discharge performance.J.Eur.Ceram.Soc.39,2889-2898(2019).) was prepared by 0-3 composite method (Bi 0.32 Sr 0.42 Na 0.20 )TiO3 / MgO composite ceramics, obtained 2.09J / cm at an electric field strength of 200kV / cm 3 The effective energy storage density and energy storage efficiency of 84% were obtained by Yang et al. from Air Force Engineering University (Z. Yang, H. Du, S. Qu, Y. Hou, H. Ma, J. Wang, J. Wang, X. Wei, Z. Xu, Significantly enhanced recoverable energy storage density in potassium-sodium niobate-based lead-free ceramics. J. Mater. Chem. A 4, 13778-13785 (2016).) through solid phase reaction method (K 0.5 Na 0.5 )NbO3-SrTiO3 solid solution ceramics, while reducing the residual polarization intensity and refining the ceramic grains, finally obtained 4.03J / cm at an electric field strength of 400kV / cm 3 The above existing technologies have always been unable to resolve the contradiction between polarization strength and breakdown electric field, resulting in the inability to significantly improve both energy storage density and efficiency at the same time, which has limited the urgent demand for high-performance lead-free ceramic materials in the rapid development of information technology. Summary of the Invention

[0004] In order to solve the above shortcomings of the prior art, the purpose of the present invention is to provide a lead-free ultra-thin ceramic material with high energy storage performance and a preparation method thereof. 0.39 Na 0.36 Sr 0.25 TiO3 ceramics, introducing high-valence Ta into the B site5+ On the one hand, it can reduce the effect of Ti element valence on leakage current and withstand voltage strength, and on the other hand, it can form a low dielectric constant Sr 0.5 BiTaTiO 6.5 phase; at the same time, the present invention prepares a lead-free ultra-thin ceramic material with a thickness of less than 20μm through a solid-phase reaction method and a tape casting molding process. The ceramic material has the characteristics of thin thickness, good density and flatness, low dielectric loss, high breakdown electric field strength, excellent energy storage performance, simple preparation method, and does not contain lead elements, which meets the needs of miniaturization and green development of electronic components.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0006] A lead-free ultra-thin ceramic material with high energy storage performance, the chemical formula of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti (1-x) Ta x O3, where x = 0.03 to 0.07.

[0007] A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance comprises the following steps:

[0008] Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain a raw material powder;

[0009] Step 2: calcining the raw material powder in step 1, wet ball milling, drying, and sieving to obtain a ceramic base material with a particle size of 70-130 μm;

[0010] Step 3: uniformly mixing the ceramic base material obtained in step 2 with an organic solvent, a dispersant, a plasticizer, a binder, and a modifier according to the weight percentages by wet ball milling to obtain a ceramic slurry;

[0011] Step 4: The ceramic slurry obtained in step 3 is tape-cast to obtain a green tape with a thickness of 12-30 μm. The green tape is cut, pressed, debonded, and then sintered under sealed conditions to obtain a lead-free ultra-thin ceramic material with high energy storage performance and a thickness of 8-20 μm.

[0012] The purity of Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 in step 1 is greater than 98%.

[0013] In the step 2, the calcination temperature is 800-900° C., and the time is 3-5 hours; the drying temperature is 80-100° C., and the time is 6-12 hours; and the sieving mesh number is 120-200 meshes.

[0014] In step 3, by weight percentage, ceramic base material: organic solvent: dispersant: plasticizer: binder: modifier = 40-50wt%: 14-20wt%: 1-2wt%: 2-4wt%: 3-5wt%: 30-40wt%.

[0015] In step 3, the organic solvent is anhydrous ethanol, the modifier is methyl ethyl ketone, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate.

[0016] The weight percentages of the polyethylene glycol and dibutyl phthalate are both 1-2 wt %.

[0017] The ball milling media for wet ball milling in steps 1-3 are all anhydrous ethanol and agate balls or ZrO2 balls, the mass ratio of anhydrous ethanol, agate balls or ZrO2 balls to the corresponding materials is (1.2-1.5):(1.5-2.0):1, the ball milling speed is 300-500r / min, and the time is 12-24h.

[0018] In step 4, the debinding temperature is 550-600°C and the time is 8-15h. The sintering process is to increase the temperature from room temperature to 1200-1240°C at a heating rate of 3-4°C / min, then quickly decrease the temperature to 1080-1120°C at a cooling rate of 20-30°C / min and keep it at that temperature for 2-4h. Then, the temperature is decreased to 800°C at a cooling rate of 3-6°C / min and then naturally cooled to room temperature in the furnace.

[0019] The pressing temperature in step 4 is 50-60°C, the pressure is 50-250 MPa, and the pressure is maintained at any pressure for 3-10 minutes. The sealing condition of the sintering is to place the debinded green strip in a sealed alumina or zirconia ark for sintering, and the outer periphery of the ark is buried with zirconia powder with a particle size of less than 70 μm.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention is achieved by 0.39 Na 0.36 Sr 0.25 Introduction of high-valence Ta into the B site of TiO3 ceramics 5+ On the one hand, it reduces the effect of Ti element valence on leakage current and withstand voltage strength, and on the other hand, it can form a low dielectric constant Sr 0.5 BiTaTiO 6.5 Phase, which improves the breakdown electric field strength of the ceramic material.

[0022] 2. The lead-free ultra-thin ceramic material prepared by the present invention does not contain lead elements, is an environmentally friendly material, complies with the current development strategy of dielectric capacitors, and has a very wide range of applications.

[0023] 3. The lead-free ultra-thin ceramic material prepared by the present invention has a thickness of less than 20 μm, a maximum electric field strength of 950 kV / cm, and an energy storage density of 9.25 J / cm 3 , the corresponding energy storage efficiency reaches 95%; compared with the existing technology, the lead-free ultra-thin ceramic material prepared by the present invention can greatly improve the energy storage density and energy storage efficiency at the same time.

[0024] 4. The preparation method of the present invention combines tape casting and pressing processes, which effectively improves the density of the lead-free ultra-thin ceramic material, is beneficial to improving its energy storage performance, and the process is simple and controllable, and has no pollution to the environment.

[0025] 5. The present invention not only suppresses grain growth but also improves the uniformity and density of ceramic grains and enhances the breakdown electric field strength of the lead-free ultra-thin ceramic material by setting the sintering process in step 4.

[0026] In summary, the present invention is achieved by 0.39 Na 0.36 Sr 0.25 Introduction of high-valence Ta into the B site of TiO3 ceramics 5+ On the one hand, it reduces the effect of Ti element valence on leakage current and withstand voltage strength, and on the other hand, it forms a low dielectric constant Sr 0.5 BiTaTiO 6.5 Phase, thus improving the breakdown electric field strength of the ceramic material. In addition, the tape-casting process used in the preparation of the lead-free ultra-thin ceramic with high energy storage performance prepared by the present invention is easy to achieve industrial mass production and can be directly used to prepare multilayer ceramic capacitors, which is of great significance for replacing lead-based energy storage ceramic dielectrics. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the XRD pattern of the lead-free ultra-thin ceramic material prepared in the present invention.

[0028] Figure 2 This is an SEM image of the cross section of the lead-free ultra-thin ceramic material prepared in the present invention.

[0029] Figure 3 This is an SEM image of the surface of the lead-free ultra-thin ceramic material prepared in the present invention.

[0030] Figure 4 This is the hysteresis loop of the lead-free ultra-thin ceramic material prepared in the present invention, wherein a, b, and c correspond to Example 1, Example 3, and Example 5, respectively.

[0031] Figure 5 This is a curve diagram of the energy storage density and energy storage efficiency of the lead-free ultra-thin ceramic material prepared in the present invention as a function of the electric field strength, wherein a, b, and c correspond to Example 1, Example 3, and Example 5, respectively.

[0032] Figure 6 The graph shows the change in dielectric constant and dielectric loss tangent of the lead-free ultra-thin ceramic material prepared in the present invention with temperature, wherein a, b, and c correspond to Example 1, Example 3, and Example 5, respectively. DETAILED DESCRIPTION

[0033] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention, and these all fall within the scope of protection of the present invention.

[0034] A lead-free ultra-thin ceramic material with high energy storage performance, the chemical formula of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti (1-x) Ta x O3, where x = 0.03 to 0.07.

[0035] A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance comprises the following steps:

[0036] Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain a raw material powder; the purity of the Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 is greater than 98%;

[0037] Step 2: calcining the raw material powder in step 1 at 800-900°C in a resistance furnace for 3-5 hours to obtain a pre-synthesized ceramic powder; wet-ball milling the pre-synthesized ceramic powder, and drying the milled slurry at 80-100°C for 6-12 hours; passing the dried ceramic powder through a 120-200 mesh sieve to obtain a ceramic base material with a particle size of 70-130 μm;

[0038] Step 3: 40-50wt% of a ceramic base material, 14-20wt% of an organic solvent, 1-2wt% of a dispersant, 2-4wt% of a plasticizer, 3-5wt% of a binder, and 30-40wt% of a modifier are mixed uniformly by wet ball milling to obtain a ceramic slurry; the organic solvent is anhydrous ethanol, the modifier is methyl ethyl ketone, which can also be used as an organic solvent, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate, wherein the weight percentages of the polyethylene glycol and dibutyl phthalate are both 1-2wt%;

[0039] Step 4: The ceramic slurry obtained in step 3 is fed into a tape casting machine for tape casting to obtain a green tape with a thickness of 12-30 μm. The green tape is cut into squares with a side length of 10 mm. The cut green tape is placed on a pressure forming machine at 50-60°C and pressurized with a pressure of 50-250 MPa. The pressure is maintained at any pressure for 3-10 minutes to reduce the pore concentration in the green tape and obtain a dense ceramic green tape. The ceramic green tape is placed in a resistance furnace at 550-600°C for debinding for 8-15 hours to remove organic matter in the ceramic green tape. The debinded ceramic green tape is then sintered under sealed conditions for 3- The temperature is raised from room temperature to 1200-1240°C at a heating rate of 4°C / min, then rapidly lowered to 1080-1120°C at a cooling rate of 20-30°C / min and kept at this temperature for 2-4 hours. The temperature is then lowered to 800°C at a cooling rate of 3-6°C / min, and then naturally cooled to room temperature with the furnace to obtain a lead-free ultra-thin ceramic material with high energy storage performance and a thickness of 8-20 μm. The sealing condition for the sintering is to place the debinded ceramic green body in a sealed alumina or zirconia ark for sintering, and the outer periphery of the ark is buried with zirconia powder that has been calcined at 1400-1550°C for 4-6 hours and ground to a particle size of less than 70 μm.

[0040] In the above steps, the ball milling speed is 300-500 r / min, and the time is 12-24 h; the ball milling media are anhydrous ethanol and ZrO2 balls; the mass ratio of anhydrous ethanol, ZrO2 balls and corresponding materials is (1.2-1.5):(1.5-2.0):1.

[0041] Example 1

[0042] A lead-free ultra-thin ceramic material with high energy storage performance, wherein x=0.03, and the chemical composition of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti 0.97 Ta 0.03 O3.

[0043] A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance comprises the following steps:

[0044] Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain a raw material powder; the purity of the Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 is greater than 98%;

[0045] Step 2: calcining the raw material powder in step 1 at 800°C in a resistance furnace for 5 hours to obtain a pre-synthesized ceramic powder; wet ball milling the pre-synthesized ceramic powder, and drying the milled slurry at 80°C for 12 hours; passing the dried ceramic powder through a 120-200 mesh sieve to obtain a ceramic base material with a particle size of 70-130 μm;

[0046] Step 3: 40 wt% of a ceramic base material, 14 wt% of an organic solvent, 1 wt% of a dispersant, 2 wt% of a plasticizer, 3 wt% of a binder, and 40 wt% of a modifier are mixed uniformly by wet ball milling to obtain a ceramic slurry; the organic solvent is anhydrous ethanol, the modifier is methyl ethyl ketone, which can also be used as an organic solvent, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate, wherein the weight percentages of the polyethylene glycol and dibutyl phthalate are both 1 wt%;

[0047] Step 4: The ceramic slurry obtained in step 3 is fed into a tape casting machine for tape casting to obtain a green tape with a thickness of 22 μm. The green tape is cut into squares with a side length of 10 mm. The cut green tape is placed on a pressure forming machine at 50°C and pressurized with pressures of 50 MPa, 100 MPa, 150 MPa, 200 MPa, and 250 MPa in sequence. The holding time is 3 minutes to reduce the pore concentration in the green tape and obtain a dense ceramic green tape. The ceramic green tape is placed in a resistance furnace at 550°C for 15 hours to remove organic matter in the ceramic green tape. Then the debinding is carried out. The ceramic green body is sintered under sealed conditions, heating from room temperature to 1200°C at a heating rate of 3°C / min, then rapidly cooling to 1080°C at a cooling rate of 20°C / min and keeping warm for 4 hours, then cooling to 800°C at a cooling rate of 3°C / min and naturally cooling to room temperature with the furnace, thereby obtaining a lead-free ultra-thin ceramic material with high energy storage performance and a thickness of 14 μm; the sealing conditions for sintering are to place the debinded ceramic green body in a sealed alumina ark for sintering, and the outer periphery of the ark is buried with zirconium oxide powder calcined at 1400°C for 6 hours and ground to a particle size of less than 70 μm.

[0048] In the above steps, the ball milling speed was 300 r / min and the time was 12 h; the ball milling media were anhydrous ethanol and ZrO2 balls; the mass ratio of anhydrous ethanol, ZrO2 balls and corresponding materials was 1.2:1.5:1.

[0049] The lead-free ultra-thin ceramic material of this embodiment has a maximum electric field strength of 866 kV / cm at room temperature and 10 Hz, and the corresponding polarization strength is higher than 40 μC / cm 2 ,like Figure 4 a; The energy storage density W calculated based on the hysteresis loop under different electric field strengths rec As the electric field strength increases, the energy storage efficiency η always remains above 90%. When the electric field strength reaches 866 kV / cm, the energy storage density W rec 9.18 J / cm 3 , the corresponding energy storage efficiency η is around 93%, as shown in Figure 5 As shown in a; at 10kHz, the dielectric constant in the temperature range from room temperature to 400℃ is higher than 1500, while the dielectric loss is less than 0.06, as shown in Figure 6 It can be seen that compared with the prior art, the lead-free ultra-thin ceramic material prepared in this embodiment greatly improves both the energy storage density and the energy storage efficiency.

[0050] Example 2

[0051] A lead-free ultra-thin ceramic material with high energy storage performance, wherein x=0.04, and the chemical composition of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti 0.96 Ta 0.04 O3.

[0052] A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance comprises the following steps:

[0053] Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain a raw material powder; the purity of the Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 is greater than 98%;

[0054] Step 2: calcining the raw material powder in step 1 at 800°C in a resistance furnace for 5 hours to obtain a pre-synthesized ceramic powder; wet ball milling the pre-synthesized ceramic powder, and drying the milled slurry at 80°C for 12 hours; passing the dried ceramic powder through a 120-200 mesh sieve to obtain a ceramic base material with a particle size of 70-130 μm;

[0055] Step 3: 41wt% of a ceramic base material, 20wt% of an organic solvent, 2wt% of a dispersant, 3wt% of a plasticizer, 4wt% of a binder, and 30wt% of a modifier are mixed uniformly by wet ball milling to obtain a ceramic slurry; the organic solvent is anhydrous ethanol, the modifier is methyl ethyl ketone, which can also be used as an organic solvent, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate, wherein the weight percentage of the polyethylene glycol is 1wt% and the weight percentage of the dibutyl phthalate is 2wt%;

[0056] Step 4: The ceramic slurry obtained in step 3 is fed into a tape casting machine for tape casting to obtain a green tape with a thickness of 30 μm. The green tape is cut into squares with a side length of 10 mm. The cut green tape is placed on a pressure forming machine at 55°C and pressurized with pressures of 50 MPa, 90 MPa, 130 MPa, 170 MPa, 210 MPa, and 250 MPa in sequence. The holding time is 5 minutes to reduce the pore concentration in the green tape and obtain a dense ceramic green tape. The ceramic green tape is placed in a resistance furnace at 550°C for debinding for 12 hours to remove organic matter in the ceramic green tape. Then The debinding ceramic green body is sintered under sealed conditions, heating from room temperature to 1220°C at a heating rate of 3°C / min, then rapidly cooling to 1100°C at a cooling rate of 20°C / min and keeping warm for 4 hours, then cooling to 800°C at a cooling rate of 5°C / min and naturally cooling to room temperature with the furnace, thereby obtaining a lead-free ultra-thin ceramic material with high energy storage performance and a thickness of 20 μm; the sealing conditions for sintering are to place the debinding ceramic green body in a sealed alumina ark for sintering, and the outer periphery of the ark is buried with zirconium oxide powder calcined at 1450°C for 5 hours and ground to a particle size of less than 70 μm.

[0057] In the above steps, the ball milling speed was 400 r / min and the time was 16 h; the ball milling media were anhydrous ethanol and ZrO2 balls; the mass ratio of anhydrous ethanol, ZrO2 balls and corresponding materials was 1.3:1.7:1.

[0058] Example 3

[0059] A lead-free ultra-thin ceramic material with high energy storage performance, wherein x=0.05, and the chemical composition of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti 0.95 Ta 0.05 O3.

[0060] A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance comprises the following steps:

[0061] Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain a raw material powder; the purity of the Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 is greater than 98%;

[0062] Step 2: calcining the raw material powder in step 1 at 850° C. in a resistance furnace for 4 hours to obtain a pre-synthesized ceramic powder; wet-milling the pre-synthesized ceramic powder, and drying the milled slurry at 90° C. for 9 hours; passing the dried ceramic powder through a 120-200 mesh sieve to obtain a ceramic base material with a particle size of 70-130 μm;

[0063] Step 3: 41wt% of a ceramic base material, 20wt% of an organic solvent, 2wt% of a dispersant, 3wt% of a plasticizer, 4wt% of a binder, and 30wt% of a modifier are mixed uniformly by wet ball milling to obtain a ceramic slurry; the organic solvent is anhydrous ethanol, the modifier is methyl ethyl ketone, which can also be used as an organic solvent, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate, wherein the weight percentage of the polyethylene glycol is 2wt% and the weight percentage of the dibutyl phthalate is 1wt%;

[0064] Step 4: The ceramic slurry obtained in step 3 is fed into a tape casting machine for tape casting to obtain a green tape with a thickness of 26 μm. The green tape is cut into squares with a side length of 10 mm. The cut green tape is placed on a pressure forming machine at 55°C and pressurized with pressures of 50 MPa, 100 MPa, 150 MPa, 200 MPa, and 250 MPa in sequence. The holding time is 7 minutes to reduce the pore concentration in the green tape and obtain a dense ceramic green tape. The ceramic green tape is placed in a resistance furnace at 570°C for 10 hours to remove organic matter in the ceramic green tape. Then the debinding is carried out. The ceramic green body is sintered under sealed conditions, heating from room temperature to 1220°C at a heating rate of 4°C / min, then rapidly cooling to 1100°C at a cooling rate of 25°C / min and keeping warm for 3 hours, then cooling to 800°C at a cooling rate of 5°C / min and naturally cooling to room temperature with the furnace, thereby obtaining a lead-free ultra-thin ceramic material with high energy storage performance and a thickness of 18 μm; the sealing conditions for sintering are to place the debinded ceramic green body in a sealed alumina ark for sintering, and the outer periphery of the ark is buried with zirconium oxide powder calcined at 1500°C for 5 hours and ground to a particle size of less than 70 μm.

[0065] In the above steps, the ball milling speed was 400 r / min and the time was 16 h; the ball milling media were anhydrous ethanol and ZrO2 balls; the mass ratio of anhydrous ethanol, ZrO2 balls and corresponding materials was 1.3:1.7:1.

[0066] The lead-free ultra-thin ceramic material of this embodiment has a maximum electric field strength of 915 kV / cm at room temperature and 10 Hz, and the corresponding polarization strength can reach 40 μC / cm 2 ,like Figure 4 b shows the energy storage density W calculated based on the hysteresis loop under different electric field strengths. rec As the electric field strength increases, the energy storage efficiency η always remains above 90%. When the electric field strength reaches 915kV / cm, the energy storage density W rec 10.06 J / cm 3 , the corresponding energy storage efficiency η is around 93%, as shown in Figure 5 As shown in Figure b, at 10kHz, the dielectric constant in the temperature range from room temperature to 400°C is higher than 1000, while the dielectric loss is less than 0.06. Figure 6 It can be seen that compared with the prior art, the lead-free ultra-thin ceramic material prepared in this embodiment greatly improves both the energy storage density and the energy storage efficiency.

[0067] Example 4

[0068] A lead-free ultra-thin ceramic material with high energy storage performance, wherein x=0.06, and the chemical composition of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti 0.94 Ta 0.06 O3.

[0069] A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance comprises the following steps:

[0070] Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain a raw material powder; the purity of the Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 is greater than 98%;

[0071] Step 2: calcining the raw material powder in step 1 at 850° C. in a resistance furnace for 4 hours to obtain a pre-synthesized ceramic powder; wet-milling the pre-synthesized ceramic powder, and drying the milled slurry at 90° C. for 9 hours; passing the dried ceramic powder through a 120-200 mesh sieve to obtain a ceramic base material with a particle size of 70-130 μm;

[0072] Step 3: 50 wt% of a ceramic base material, 14 wt% of an organic solvent, 1 wt% of a dispersant, 2 wt% of a plasticizer, 3 wt% of a binder, and 30 wt% of a modifier are mixed uniformly by wet ball milling to obtain a ceramic slurry; the organic solvent is anhydrous ethanol, the modifier is methyl ethyl ketone, which can also be used as an organic solvent, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate, wherein the weight percentages of the polyethylene glycol and dibutyl phthalate are both 1 wt%;

[0073] Step 4: The ceramic slurry obtained in step 3 is fed into a tape casting machine for tape casting to obtain a green tape with a thickness of 12 μm. The green tape is cut into squares with a side length of 10 mm. The cut green tape is placed on a pressure forming machine at 55°C and pressurized with pressures of 50 MPa, 110 MPa, 170 MPa, 230 MPa, and 250 MPa in sequence. The holding time is 9 minutes to reduce the pore concentration in the green tape and obtain a dense ceramic green tape. The ceramic green tape is placed in a resistance furnace at 570°C for 12 hours to remove the organic matter in the ceramic green tape. The debonded ceramic green body is sintered under sealed conditions, heating from room temperature to 1220°C at a heating rate of 4°C / min, then rapidly cooling to 1100°C at a cooling rate of 25°C / min and keeping warm for 3 hours, then cooling to 800°C at a cooling rate of 5°C / min and naturally cooling to room temperature with the furnace, thereby obtaining a lead-free ultra-thin ceramic material with high energy storage performance and a thickness of 8 μm; the sealing conditions for sintering are to place the debonded ceramic green body in a sealed zirconia ark for sintering, and the outer periphery of the ark is buried with zirconia powder calcined at 1450°C for 5 hours and ground to a particle size of less than 70 μm.

[0074] In the above steps, the ball milling speed was 400 r / min and the time was 16 h; the ball milling media were anhydrous ethanol and agate balls; the mass ratio of anhydrous ethanol, agate balls and corresponding materials was 1.3:1.7:1.

[0075] Example 5

[0076] A lead-free ultra-thin ceramic material with high energy storage performance, wherein x=0.07, and the chemical composition of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti 0.93 Ta 0.07 O3.

[0077] A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance comprises the following steps:

[0078] Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain a raw material powder; the purity of the Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 is greater than 98%;

[0079] Step 2: calcining the raw material powder in step 1 at 900°C in a resistance furnace for 3 hours to obtain a pre-synthesized ceramic powder; wet ball milling the pre-synthesized ceramic powder, and drying the milled slurry at 100°C for 6 hours; passing the dried ceramic powder through a 120-200 mesh sieve to obtain a ceramic base material with a particle size of 70-130 μm;

[0080] Step 3: 45 wt% of a ceramic base material, 14 wt% of an organic solvent, 2 wt% of a dispersant, 4 wt% of a plasticizer, 5 wt% of a binder, and 30 wt% of a modifier are mixed uniformly by wet ball milling to obtain a ceramic slurry; the organic solvent is anhydrous ethanol, the modifier is methyl ethyl ketone, which can also be used as an organic solvent, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate, wherein the weight percentages of the polyethylene glycol and dibutyl phthalate are both 2 wt%;

[0081] Step 4: The ceramic slurry obtained in step 3 is fed into a tape casting machine for tape casting to obtain a green tape with a thickness of 20 μm. The green tape is cut into squares with a side length of 10 mm. The cut green tape is placed on a pressure forming machine at 60°C and pressurized with pressures of 50 MPa, 100 MPa, 150 MPa, 200 MPa, and 250 MPa in sequence. The holding time is 10 minutes to reduce the pore concentration in the green tape and obtain a dense ceramic green tape. The ceramic green tape is placed in a resistance furnace for debinding at 600°C for 8 hours to remove organic matter in the ceramic green tape. The ceramic green body is sintered under sealed conditions, heating from room temperature to 1240°C at a heating rate of 4°C / min, then rapidly cooling to 1120°C at a cooling rate of 30°C / min and keeping warm for 2 hours, then cooling to 800°C at a cooling rate of 5°C / min and naturally cooling to room temperature with the furnace, thereby obtaining a lead-free ultra-thin ceramic material with high energy storage performance and a thickness of 15 μm; the sealing conditions for sintering are to place the debinded ceramic green body in a sealed zirconia ark for sintering, and the outer periphery of the ark is buried with zirconia powder calcined at 1550°C for 4 hours and ground to a particle size of less than 70 μm.

[0082] In the above steps, the ball milling speed was 400 r / min and the time was 16 h; the ball milling media were anhydrous ethanol and agate balls; the mass ratio of anhydrous ethanol, agate balls and corresponding materials was 1.5:2.0:1.

[0083] The lead-free ultra-thin ceramic material of this embodiment has a maximum electric field strength of 950 kV / cm at room temperature and 10 Hz, and the corresponding polarization strength is higher than 30 μC / cm 2 ,like Figure 4 c shows the energy storage density W calculated based on the hysteresis loop under different electric field strengths. rec As the electric field strength increases, the energy storage efficiency η always remains above 90%. When the electric field strength reaches 950kV / cm, the energy storage density W rec 9.25 J / cm 3 , the corresponding energy storage efficiency η is around 95%, such as Figure 5 c; at 10kHz, the dielectric constant in the temperature range from room temperature to 400℃ is higher than 1000, while the dielectric loss is less than 0.05, as shown in Figure 6 As shown in c. It can be seen that compared with the prior art, the lead-free ultra-thin ceramic material prepared in this embodiment greatly improves both the energy storage density and the energy storage efficiency.

[0084] Figure 1 The XRD pattern of the lead-free ultra-thin ceramic material prepared in Example 1 of the present invention is shown in FIG. Figure 1 It can be seen that the main crystal phase of the ceramic material is perovskite structure, and Sr 0.5 BiTaTiO 6.5 Phase, which has the characteristics of a paraelectric phase, has a dielectric constant of about 100, which improves the breakdown electric field strength of the ceramic material. Figure 2 and Figure 3 As shown, the lead-free ultra-thin ceramic material prepared in Example 1 of the present invention has a thickness of about 14 μm, and the cross section shows good flatness. In addition, the lead-free ultra-thin ceramic material is sintered densely without obvious holes.

Claims

1. A method for preparing a lead-free ultra-thin ceramic material with high energy storage performance, characterized by: The steps include: Step 1: Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 are mixed uniformly in a stoichiometric ratio by wet ball milling to obtain raw material powder; the chemical formula of the lead-free ultra-thin ceramic material is Bi 0.39 Na 0.36 Sr 0.25 Ti (1-x) Ta x O3, where x = 0.03 to 0.07; Step 2: calcining the raw material powder in step 1, wet ball milling, drying, and sieving to obtain a ceramic base material with a particle size of 70-130 μm; Step 3: The ceramic base material obtained in step 2 is mixed uniformly with an organic solvent, a dispersant, a plasticizer, a binder, and a modifier by wet ball milling to obtain a ceramic slurry; in weight percentage, the ceramic base material: organic solvent: dispersant: plasticizer: binder: modifier = 40-50wt%: 14-20wt%: 1-2wt%: 2-4wt%: 3-5wt%: 30-40wt%; the modifier is methyl ethyl ketone; Step 4: tape-cast the ceramic slurry obtained in step 3 to obtain a green tape with a thickness of 12-30 μm, cut the green tape, press it, remove the binder, and then sinter it under sealed conditions to obtain a lead-free ultra-thin ceramic material with a thickness of 8-20 μm and high energy storage performance. The lead-free ultra-thin ceramic material has a perovskite phase as the main crystal phase and contains Sr 0.5 BiTaTiO 6.5 phase; the pressing temperature is 50-60°C, the pressure is 50-250MPa, and the pressure is maintained at any pressure for 3-10min; the sintering process is to increase the temperature from room temperature to 1200-1240°C at a heating rate of 3-4°C / min, then quickly decrease the temperature to 1080-1120°C at a cooling rate of 20-30°C / min and keep it for 2-4h, then decrease the temperature to 800°C at a cooling rate of 3-6°C / min and then naturally cool to room temperature with the furnace.

2. The method for preparing a lead-free ultra-thin ceramic material with high energy storage performance according to claim 1, characterized in that: The purity of Bi2O3, TiO2, Na2CO3, SrCO3 and Ta2O5 in step 1 is greater than 98%.

3. The method for preparing a lead-free ultra-thin ceramic material with high energy storage performance according to claim 1, characterized in that: In the step 2, the calcination temperature is 800-900° C., and the time is 3-5 hours; the drying temperature is 80-100° C., and the time is 6-12 hours; and the sieving mesh number is 120-200 meshes.

4. The method for preparing a lead-free ultra-thin ceramic material with high energy storage performance according to claim 1, characterized in that: In step 3, the organic solvent is anhydrous ethanol, the dispersant is triolein, the binder is polyvinyl butyral, and the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate.

5. The method for preparing a lead-free ultra-thin ceramic material with high energy storage performance according to claim 4, characterized in that: The weight percentages of the polyethylene glycol and dibutyl phthalate are both 1-2 wt %.

6. The method for preparing a lead-free ultra-thin ceramic material with high energy storage performance according to claim 1, characterized in that: The ball milling media for wet ball milling in steps 1-3 are all anhydrous ethanol and agate balls or ZrO2 balls, the mass ratio of anhydrous ethanol, agate balls or ZrO2 balls to the corresponding materials is (1.2-1.5):(1.5-2.0):1, the ball milling speed is 300-500r / min, and the time is 12-24h.

7. The method for preparing a lead-free ultra-thin ceramic material with high energy storage performance according to claim 1, characterized in that: In step 4, the debinding temperature is 550-600° C. and the time is 8-15 hours.

8. The method for preparing a lead-free ultra-thin ceramic material with high energy storage performance according to claim 1, characterized in that: The sealing condition for sintering in step 4 is to place the debinded green strip in a sealed alumina or zirconia ark for sintering, and the outer periphery of the ark is buried with zirconia powder with a particle size of less than 70 μm.

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