Potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material and preparation method thereof

Abstract

The present invention discloses a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material and a preparation method thereof. The chemical formula of the energy storage ceramic material is (0.9- x )K 0.5 Na 0.5 NbO3‑ x LaBiO3-0.1NaNbO3, where 0.02≤x≤0.045, is prepared according to the general chemical formula, ball-milled, and then granulated with a binder. The ceramic sheet is pressed and formed, and the binder is removed and sintered to obtain an energy storage ceramic material. The present invention adopts the above-mentioned potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material and its preparation method. By adding an appropriate amount of lanthanum bismuthate and sodium niobate, the grain refinement of the potassium sodium niobate ceramic is promoted, the density is increased, and a high maximum polarization intensity P is obtained. m , lower residual polarization intensity P r and high breakdown field strength DBS, thereby obtaining excellent energy storage characteristics. In addition, the present invention is simple to operate, has a wide source of raw materials, has low equipment cost, meets environmental protection requirements, and is easy to apply.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and in particular to a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material and a preparation method thereof. Background Art

[0002] The energy storage system is the core component of a pulsed power system, and its performance directly impacts its output characteristics. Solid-state dielectric capacitors made of ceramic-based materials offer high power density, fast charge and discharge speeds, a wide temperature and frequency range, high safety, and low cost, meeting the requirements of ultra-high power electronic systems. However, the energy storage density of ceramic materials is currently relatively low, failing to meet the demands of miniaturized pulsed power devices and limiting their application.

[0003] Lead-based antiferroelectric energy storage ceramics are the most widely used due to their high energy storage properties. However, since lead has great harm to the environment and human health, countries have successively banned the use of lead-containing materials in electronic and electrical equipment. Therefore, the research and development of lead-free green energy storage ceramic materials with high energy storage density has become one of the research hotspots of new ferroelectric ceramics. Summary of the Invention

[0004] The purpose of the present invention is to provide a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material and a preparation method thereof, so as to solve the problems of low compactness and low energy storage density of the above-mentioned lead-free energy storage ceramic material.

[0005] To achieve the above objectives, the first aspect of the present invention provides a potassium sodium niobate-lanthanum bismuthate-sodium niobate based energy storage ceramic material, the chemical formula of the energy storage ceramic material is (0.9- x )K 0.5 Na 0.5 NbO3- x LaBiO3-0.1NaNbO3, where 0.02≤x≤0.045.

[0006] Preferably, 0.02<x≤0.045.

[0007] Preferably, 0.02≤x<0.045.

[0008] Preferably, the total energy storage density W of the energy storage ceramic material is 7-19 J / cm 3 , energy storage efficiency η The breakdown field strength DBS is 560-1500kV / cm.

[0009] Preferably, x=0.035.

[0010] Preferably, the total energy storage density W of the energy storage ceramic material is 18.83 J / cm 3 , energy storage efficiency η It is 73.08%, and the breakdown field strength DBS is 1500kV / cm.

[0011] A second aspect of the present invention provides a method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material, comprising the following steps:

[0012] Step 1: According to the chemical formula (0.9- x )K 0.5 Na 0.5 NbO3- x The stoichiometric ratio of LaBiO3-0.1NaNbO3 is used for batching;

[0013] Step 2: ball milling the raw materials and then pre-synthesizing them into ceramic powder;

[0014] Step 3: ball mill the ceramic powder again and dry it;

[0015] Step 4: Adding a binder to the dried ceramic powder for granulation, and then pressing the ceramic powder into a shape to obtain a ceramic sheet;

[0016] Step 5: Debinding the obtained ceramic sheet and then sintering it to obtain potassium sodium niobate-lanthanum bismuthate-sodium niobate based ceramic material.

[0017] Preferably, the raw material used in step 1 is an oxide or carbonate containing five elements: K, Na, Nb, La, and Bi.

[0018] Preferably, the raw materials used in step 1 are potassium carbonate K2CO3, sodium carbonate Na2CO3, niobium pentoxide Nb2O5, lanthanum oxide La2O3 and bismuth oxide Bi2O3 powders.

[0019] Preferably, step 2 comprises the following steps,

[0020] Step 2a: Place the prepared raw materials into a ball mill using zirconium oxide as a ball mill, use anhydrous ethanol as a dispersant, and place them in a planetary ball mill for 8-24 hours. The speed of the planetary ball mill is set to 100-450 rpm.

[0021] Step 2b, baking the evenly mixed slurry under a drying lamp for 2-3 hours;

[0022] Step 2c: Place the dried product in a programmable temperature-controlled box furnace, raise the temperature from room temperature to 800-900° C., keep the temperature for 4-6 hours, and cool it to room temperature with the furnace to obtain ceramic powder.

[0023] Preferably, step 3 comprises the following steps,

[0024] Step 3a: The ceramic powder is placed in a ball mill using zirconium oxide as a ball mill, anhydrous ethanol is used as a dispersant, and the powder is milled in a planetary ball mill for 8-24 hours at a speed of 100-450 rpm.

[0025] Step 3b: bake the evenly mixed slurry under a drying lamp for 2-3 hours.

[0026] Preferably, the binder used in step 4 is a 5-10wt% polyvinyl alcohol solution, and the granulation size is 60-120 mesh; the granulated particles are pressed into ceramic discs at a pressure of 8-10 MPa, and the obtained ceramic discs have a diameter of 8-15 mm and a thickness of 0.8-1.2 mm.

[0027] Preferably, in step 5, the debinding temperature is 500-850° C., the sintering temperature is 1000-1200° C., and the sintering time is 2-6 hours.

[0028] Therefore, the present invention adopts a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material and a preparation method thereof with the above structure, which has the following beneficial effects:

[0029] (1) The present invention promotes grain refinement and improves density by doping lanthanum bismuthate and sodium niobate, thereby obtaining a high maximum polarization intensity value, a low residual polarization intensity and a high breakdown field strength, thereby obtaining excellent energy storage characteristics.

[0030] (2) The present invention is easy to operate, has a wide range of raw materials, has low equipment costs, and is easy to apply; the energy storage density W of the potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material prepared according to the method provided by the present invention can reach up to 18.83 J / cm 3 , the energy storage efficiency η is 73.08%.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A ferroelectric loop of the ceramic material prepared in Example 3 of the present invention;

[0033] Figure 2 A comparison diagram of the ferroelectric loop of the ceramic material prepared in Example 3 of the present invention and the ferroelectric loop of the ceramic material of Comparative Examples 1-4;

[0034] Figure 3 This is a scanning electron microscope (SEM) photograph of the ceramic material prepared in Example 3 of the present invention;

[0035] Figure 4 The high-temperature dielectric curve of the ceramic material prepared in Examples 1-4 of the present invention;

[0036] Figure 5 X-ray diffraction patterns of the ceramic materials prepared in Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the present invention is not limited to this embodiment.

[0038] The present invention provides a preparation method of a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material. The conventional solid-phase preparation process can be used to promote grain refinement by doping lanthanum bismuthate and sodium niobate into the potassium sodium niobate-based ceramic, thereby obtaining excellent energy storage properties. The raw materials include potassium carbonate K2CO3, sodium carbonate Na2CO3, niobium pentoxide Nb2O5, lanthanum oxide La2O3 and bismuth oxide Bi2O3 powder.

[0039] Example 1

[0040] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0041] Step 1, according to the chemical formula (0.9-x)k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.025;

[0042] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0043] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0044] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0045] Step 5: Debind the obtained ceramic disc at 550°C and then sinter it at 1155°C for 3 hours to obtain 1# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0046] Example 2

[0047] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0048] Step 1, according to the chemical formula (0.9-x)k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.03;

[0049] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0050] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0051] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0052] Step 5: Debinding the obtained ceramic disc at 550° C. and then sintering it at 1155° C. for 3 hours to obtain 2# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0053] Example 3

[0054] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0055] Step 1, according to the chemical formula (0.9-x)k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.035;

[0056] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0057] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0058] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0059] Step 5: Debind the obtained ceramic disc at 550° C. and then sinter it at 1155° C. for 3 hours to obtain 3# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0060] Example 4

[0061] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0062] Step 1, according to the chemical formula (0.9-x)k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.04;

[0063] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0064] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0065] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0066] In step 5, the obtained ceramic disc is debinded at 550°C and then sintered at 1155°C for 3 h to obtain 4# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0067] Example 5

[0068] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0069] Step 1, according to the chemical formula (0.9-x)k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.045;

[0070] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0071] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0072] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0073] In step 5, the obtained ceramic disc is debinded at 550°C and then sintered at 1155°C for 3 h to obtain 5# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0074] Example 6

[0075] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0076] Step 1, according to the chemical formula (0.9-x)k0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.02;

[0077] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0078] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0079] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0080] Step 5: Debind the obtained ceramic disc at 550°C and then sinter it at 1155°C for 3 hours to obtain 6# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0081] Comparative Example 1

[0082] A method for preparing potassium sodium niobate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0083] Step 1, according to the chemical formula 0.9k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-0.1NaNbO3, where x=0;

[0084] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0085] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0086] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0087] Step 5: Debinding the obtained ceramic disc at 550° C. and then sintering it at 1100° C. for 3 hours to obtain potassium sodium niobate-sodium niobate-based ceramic material.

[0088] Comparative Example 2

[0089] A method for preparing a potassium sodium niobate-lanthanum bismuthate-based energy storage ceramic material comprises the following steps:

[0090] Step 1, according to the chemical formula (0.9-x)k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-0.035LaBiO3, where x=0.035;

[0091] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0092] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0093] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0094] Step 5: Debinding the obtained ceramic disc at 550° C. and then sintering it at 1150° C. for 3 hours to obtain potassium sodium niobate-lanthanum bismuthate-based ceramic material.

[0095] Comparative Example 3

[0096] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0097] Step 1, according to the chemical formula (0.9-x)k0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.01;

[0098] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0099] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0100] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0101] Step 5: Debinding the obtained ceramic disc at 550° C. and then sintering it at 1155° C. for 3 h to obtain potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0102] Comparative Example 4

[0103] A method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material comprises the following steps:

[0104] Step 1, according to the chemical formula (0.9-x)k 0.5 Na 0.5 The ingredients are prepared in the stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3, where x=0.06;

[0105] Step 2: The prepared raw materials were placed in a nylon ball mill with zirconia as the ball mill, anhydrous ethanol was used as the dispersant, and the mixture was ball milled for 12 hours in a planetary ball mill at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours and then pre-calcined in a programmable temperature-controlled box furnace at 900°C for 4 hours to obtain a ceramic powder.

[0106] Step 3: The ceramic powder was again placed in a nylon ball mill with zirconium oxide as the ball mill, and anhydrous ethanol was used as a dispersant. The powder was then placed in a planetary ball mill and ball milled for 12 hours at a speed of 200 rpm. The mixed slurry was then baked under a drying lamp for 2 hours.

[0107] Step 4: Add 5 wt% of a polyvinyl alcohol solution binder to the dried ceramic powder for granulation. The granulation size is 120 mesh. The ceramic powder is then pressed under a pressure of 10 MPa to obtain ceramic discs with a diameter of 8 mm and a thickness of 0.8 mm.

[0108] Step 5: Debinding the obtained ceramic disc at 550° C. and then sintering it at 1155° C. for 3 h to obtain potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material.

[0109] The principle of the present invention is that the breakdown field strength is mainly related to factors such as the grain size, pores and density of the ceramic material, among which the grain size is the most important factor. The present invention can reduce the grain size by doping lanthanum bismuthate and sodium niobate into KNN-based ceramic materials, adjust the grain size to submicron level, increase the density of the ceramic and reduce the pore content, thereby improving the breakdown field strength and obtaining excellent energy storage characteristics. 3+ The maximum polarization strength (Pmax) of the ceramic can be increased, thereby increasing ΔP. This is because the hybridization of the 6s orbital of Bi and the 2p orbital of O enhances polarity. Incorporating the rare earth element La into KNN ceramics can enhance the ceramic's relaxivity and increase the breakdown field strength (BDS), which is beneficial for improving the energy storage properties of KNN ceramics. Therefore, incorporating LaBiO3 and NaNbO3 into KNN ceramics can reduce grain size, enhance the density of KNN ceramics, increase the breakdown field strength, and improve energy storage properties.

[0110] The above examples 1-4 respectively prepared 1-4# ceramic materials, wherein x The values of are 0.025, 0.03, 0.035, and 0.04, respectively. Phase structure analysis, surface morphology observation, high-temperature dielectric curve test, and ferroelectric loop test were conducted on the above four ceramic materials. Unless otherwise specified, the methods used are conventional methods.

[0111] The ferroelectric loops of 1-4# ceramic materials were tested using the Radiant ferroelectric workstation. The ferroelectric loop of 3# ceramic material was as follows: Figure 1 The energy storage density of the ceramic material is calculated by the following formula: W and energy storage efficiency η :

[0112] ; ; .

[0113] in W is the energy storage density, W rec is the effective energy storage density, η is the energy storage efficiency, p max is the maximum polarization intensity value, p r is the remanent polarization intensity value, p is the polarization intensity, E is the electric field strength.

[0114] Figure 1 The horizontal axis is the electric field intensity, and the vertical axis is the polarization intensity. Figure 1 It can be seen that the ferroelectric loop of 1# ceramic material has a very high breakdown field strength (BDS) and a high maximum polarization intensity ( p max ) and lower remnant polarization intensity ( p r ), the energy storage performance of potassium sodium niobate-lanthanum bismuthate-sodium niobate based ceramic material is calculated by the above formula as shown in Table 1. The ceramic has excellent energy storage characteristics, high energy storage density (W), high energy storage efficiency ( η ) and high breakdown field strength (BDS).

[0115]

[0116] It can be seen from Table 1 that the energy storage density of 1-4# potassium sodium niobate-lanthanum bismuthate-sodium niobate based ceramic materials increases with x The increase first increases and then decreases. The comprehensive energy storage performance is the best at 3# ceramic material, which has high energy storage density, energy storage efficiency and breakdown field strength. Therefore, it can be deduced that x The preferred value is 0.035 and is in the range of 0.03-0.04.

[0117] The ferroelectric loops of the ceramic materials of Comparative Examples 1-2 and Examples 5-6 were tested using a Radiant ferroelectric workstation. Figure 2 As shown, the ferroelectric loops of the ceramic materials of Comparative Examples 1-2 and Examples 5-6 are compared with the ferroelectric loops of the 3# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material. It can be seen that the 3# ceramic material has the highest breakdown field strength (BDS) and a relatively high maximum polarization intensity ( p max ) and moderate remnant polarization ( p r), in general, 3# ceramic material has the highest effective energy storage density and relatively high energy storage efficiency.

[0118] The surface morphology of the ceramic material was observed by a Hitachi / S-3400N electron microscope. Figure 3 .from Figure 3 It can be seen that the grain size of 3# potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material is small and uniform, with no obvious pores, indicating that the ceramic material has a high density, which is conducive to improving the energy storage properties of the material.

[0119] The high temperature dielectric curve of 1-4#KNNLB ceramic material is obtained by testing with TH2816A / HP4980 impedance (LCR) analyzer. Figure 4 shown. Figure 4 The horizontal axis is temperature, and the vertical axis is relative dielectric constant. Figure 4 It can be seen that within the tested temperature range, there are two dielectric peaks in the KNNLB ceramic material ( T O-T , T C ), which indicates that there are two phase transitions in the ceramic, namely, from orthorhombic phase to tetragonal phase, and then from tetragonal phase to cubic phase, and with the increase of lanthanum bismuthate doping content, the two dielectric peaks become more and more gentle, indicating that 1-4# potassium sodium niobate-lanthanum bismuthate-sodium niobate based ceramic material has obvious relaxation phenomenon.

[0120] The phase structure of 1-4#KNNLB ceramic material was analyzed by PANalytical / DY120 X-ray diffractometer. Figure 5 shown. Figure 5 The horizontal axis represents the double angle, and the vertical axis represents the diffraction intensity. The results show that the potassium sodium niobate-lanthanum bismuthate-sodium niobate-based ceramic material exhibits a single perovskite structure with no secondary phases, demonstrating that the doped components are incorporated into the KNN lattice, forming a single solid solution. The splitting of the X-ray diffraction peak near the 45-cell mark indicates that the ceramic exhibits a pseudocubic structure at room temperature.

[0121] Therefore, the present invention adopts a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material with the above structure and a preparation method thereof, and promotes grain refinement of the potassium sodium niobate ceramic by adding appropriate amounts of lanthanum bismuthate and sodium niobate, thereby improving the density, obtaining a high maximum polarization intensity Pm, a low residual polarization intensity Pr, and a high breakdown field strength DBS, thereby obtaining excellent energy storage characteristics. In addition, the present invention is simple to operate, has a wide source of raw materials, has low equipment cost, meets environmental protection requirements, and is easy to apply.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material, characterized by: The general chemical formula of energy storage ceramic materials is (0.9-x)K 0.5 Na 0.5 NbO3-xLaBiO3-0.1NaNbO3, where x=0.035; the total energy storage density W of the energy storage ceramic material is 18.83 J / cm 3 , the energy storage efficiency η is 73.08%, and the breakdown field strength DBS is 1500kV / cm.

2. The method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material according to claim 1, characterized in that: The following steps are involved: Step 1: According to the chemical formula (0.9-x)K 0.5 Na 0.5 The stoichiometric ratio of NbO3-xLaBiO3-0.1NaNbO3 is used for batching; Step 2: ball milling the raw materials and then pre-synthesizing them into ceramic powder; Step 3: ball mill the ceramic powder again and dry it; Step 4: Adding a binder to the dried ceramic powder for granulation, and then pressing the ceramic powder into a shape to obtain a ceramic sheet; Step 5: Debinding the obtained ceramic sheet and then sintering it to obtain potassium sodium niobate-lanthanum bismuthate-sodium niobate based ceramic material.

3. The method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material according to claim 2, characterized in that: The raw materials used in step 1 are oxides or carbonates containing five elements: K, Na, Nb, La, and Bi.

4. The method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material according to claim 2, characterized in that: Step 2 includes the following steps, Step 2a: Place the prepared raw materials into a ball mill using zirconium oxide as a ball mill, use anhydrous ethanol as a dispersant, and place them in a planetary ball mill for 8-24 hours. The speed of the planetary ball mill is set to 100-450 rpm. Step 2b, baking the evenly mixed slurry under a drying lamp for 2-3 hours; Step 2c: Place the dried product in a programmable temperature-controlled box furnace, raise the temperature from room temperature to 800-900° C., keep the temperature for 4-6 hours, and cool it to room temperature with the furnace to obtain ceramic powder.

5. The method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material according to claim 2, characterized in that: Step 3 includes the following steps, Step 3a: The ceramic powder is placed in a ball mill using zirconium oxide as a ball mill, anhydrous ethanol is used as a dispersant, and the powder is milled in a planetary ball mill for 8-24 hours at a speed of 100-450 rpm. Step 3b: bake the evenly mixed slurry under a drying lamp for 2-3 hours.

6. The method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material according to claim 2, characterized in that: The binder used in step 4 is a 5-10wt% polyvinyl alcohol solution, and the granulation size is 60-120 mesh; the granulated particles are pressed into ceramic discs at a pressure of 8-10 MPa. The obtained ceramic discs have a diameter of 8-15 mm and a thickness of 0.8-1.2 mm.

7. The method for preparing a potassium sodium niobate-lanthanum bismuthate-sodium niobate-based energy storage ceramic material according to claim 2, characterized in that: In step 5, the debinding temperature is 500-850°C, the sintering temperature is 1000-1200°C, and the sintering time is 2-6 hours.

Images