Barium ferrite composite material and its preparation method and application

Abstract

The present invention discloses a barium ferrite composite material, its preparation method, and its application, belonging to the field of battery technology. The barium ferrite composite material comprises a barium ferrite core and a conductive shell coating the barium ferrite core; the conductive shell is made of at least one of copper, silver, and gold. While retaining the advantages of barium ferrite, the conductive shell further enhances the conductivity and structural stability of the barium ferrite composite material, making it potentially suitable for use in lithium-ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a barium ferrite composite material and a preparation method and application thereof. Background Art

[0002] Barium ferrite (BaFe 12 O 19 ) is a hexagonal ferrite material with high Curie temperature, high coercive force, high magnetic anisotropy, excellent chemical stability and corrosion resistivity, and is commonly used as a magnetic material.

[0003] Barium ferrite materials can be used not only as wave absorbing materials, but also as permanent magnet materials, laser modulation materials, radio materials, etc. However, due to the low conductivity of barium ferrite materials and other reasons, the application of barium ferrite materials in the battery field is relatively rare. Summary of the Invention

[0004] In view of this, the present invention provides a barium ferrite composite material and a preparation method and application thereof, which can solve the technical problems existing in the related technologies.

[0005] Specifically, the following technical solutions are included:

[0006] In one aspect, a barium ferrite composite material is provided, comprising a barium ferrite core and a conductive shell layer covering the barium ferrite core.

[0007] The material of the conductive shell layer is selected from at least one of copper, silver and gold.

[0008] In some possible implementations, the conductive shell layer is a copper layer.

[0009] In some possible implementations, the thickness of the conductive shell is 5 mm-15 mm.

[0010] On the other hand, a method for preparing a barium ferrite composite material is provided, wherein the barium ferrite composite material is as described above;

[0011] The preparation method of the barium ferrite composite material comprises:

[0012] Providing barium ferrite powder and a metal plating solution, wherein the metal plating solution includes a metal salt, and the metal salt is selected from at least one of cuprate, silverate, and gold salt;

[0013] The barium ferrite powder and the metal plating solution are mixed, and a conductive shell layer is plated on the surface of the barium ferrite core through a chemical plating process to prepare the barium ferrite composite material.

[0014] In some possible implementations, the barium ferrite composite material is prepared by mixing the barium ferrite powder and the metal plating solution and plating a conductive shell on the surface of the barium ferrite core by a chemical plating process, including:

[0015] The mixed solution of the barium ferrite powder and the metal plating solution is stirred at 20° C.-30° C., and when the mixed solution is in a clear state, the stirring is stopped, and the product system is centrifuged, washed, and dried in sequence to obtain the barium ferrite composite material.

[0016] In some possible implementations, the metal plating solution includes: 1g / L-10g / L of metal salt, 1g / L-12g / L of sodium hydroxide, 3ml / L-27ml / L of formaldehyde, and 3g / L-50g / L of potassium sodium tartrate.

[0017] In some possible implementations, the mass ratio of the barium ferrite powder to the metal salt is 1:0.5-5.

[0018] In some possible implementations, the barium ferrite powder is prepared by the following method:

[0019] The barium metal salt, the iron metal salt and the alkaline solution are mixed uniformly, and then subjected to a hydrothermal reaction;

[0020] The product system is centrifuged, washed and dried in sequence to obtain a barium ferrite precursor;

[0021] The barium ferrite precursor is calcined to obtain the barium ferrite powder.

[0022] In some possible implementations, the temperature of the hydrothermal treatment is 180° C.-200° C., and the hydrothermal treatment time is 20 h-24 h.

[0023] In another aspect, a use of any of the above-mentioned barium ferrite composite materials in the preparation of lithium-ion batteries is provided.

[0024] The beneficial effects of the technical solution provided by the embodiment of the present invention include at least:

[0025] The barium ferrite composite material provided in an embodiment of the present invention has a conductive shell layer provided on the outer surface of the barium ferrite core, and the material of the conductive shell layer is selected from at least one of copper, silver, and gold. In this way, the barium ferrite composite material provided in an embodiment of the present invention maintains the advantages of barium ferrite, and the conductive shell layer is also beneficial to improving the conductivity and structural stability of the barium ferrite composite material, so that the barium ferrite composite material has the potential to be used in lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 SEM images of the barium ferrite powder and the barium ferrite composite material provided in Example 1 at different magnifications, wherein Figures a and b correspond to the barium ferrite powder, and Figures c and d correspond to the barium ferrite composite material;

[0028] Figure 2 Characterization atlas of the barium ferrite composite material provided in Example 1, wherein ac figures are TEM images of the barium ferrite composite material at different scales, d figure is the overall spectrum of the barium ferrite composite material, and ei figure is the mapping diagram of each element in the barium ferrite composite material;

[0029] Figure 3 XRD patterns of barium ferrite powder corresponding to the molar ratios of Ba to Fe provided in Test Example 1, when the barium metal salt and the iron metal salt are mixed to achieve molar ratios of Ba to Fe of 1:9, 1:10, 1:11, and 1:12, respectively;

[0030] Figure 4 XRD patterns of the barium ferrite composite materials provided in Examples 1 to 4;

[0031] Figure 5 is a rate performance diagram of a lithium-ion battery obtained based on the barium ferrite composite material of Example 1, wherein: Figure 5 The small picture in the lower left corner is the overall test picture of the rate performance. Figure 5 The large figure shown is a partially enlarged rate performance figure;

[0032] Figure 6 This is the impedance diagram of the barium ferrite powder and the barium ferrite composite material provided in Example 1, wherein: Figure 6 The small picture in the upper right corner is the overall impedance test diagram. Figure 6 The large image shown is a locally enlarged impedance diagram.

[0033] The above drawings illustrate specific embodiments of the present invention, which will be described in more detail below. These drawings and the accompanying description are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] To make the technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0036] In one aspect, an embodiment of the present invention provides a barium ferrite composite material comprising a barium ferrite core and a conductive shell coating the barium ferrite core, wherein the conductive shell is made of at least one of copper, silver, and gold.

[0037] The barium ferrite composite material provided by the embodiment of the present invention is a composite material with a core-shell structure, wherein the barium ferrite core is composed of barium ferrite (BaFe 12 O 19 ) material, and its conductive shell is composed of at least one of copper, silver and gold materials.

[0038] The barium ferrite composite material provided by the embodiment of the present invention is provided with a conductive shell layer on the outside of the barium ferrite core, and the material of the conductive shell layer is selected from at least one of copper, silver, and gold. In this way, the barium ferrite composite material provided by the embodiment of the present invention maintains the advantages of barium ferrite, and the conductive shell layer is also beneficial to improving the conductivity and structural stability of the barium ferrite composite material, so that the barium ferrite composite material has the potential to be used in lithium-ion batteries.

[0039] As mentioned above, the conductive shell layer includes but is not limited to a copper layer, a silver layer, a gold layer, a copper-silver alloy layer, a copper-gold alloy layer, a gold-silver alloy layer, and the like.

[0040] In some examples, the barium ferrite composite material provided by the embodiments of the present invention has a conductive shell layer of copper. Using the copper layer as the conductive shell layer can maintain good conductivity and structural stability of the barium ferrite composite material while also having low cost.

[0041] In the embodiment of the present invention, the average particle size of the barium ferrite core is 1.0um-2.5um, including but not limited to: 1.0um, 1.5um, 2um, 2.5um, etc.

[0042] The thickness of the conductive shell layer can be adaptively designed according to the actual application requirements of the barium ferrite composite material. In some examples, the thickness of the conductive shell layer is 5mm-15mm, including but not limited to: 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, etc.

[0043] The conductive shell layer of the barium ferrite composite material provided by the embodiment of the present invention can be formed on the surface of the barium ferrite core in a variety of ways, including but not limited to: chemical plating process.

[0044] The conductive shell is formed on the surface of the barium ferrite core by using a chemical plating process, which not only makes the conductive shell and the barium ferrite core have a stronger bonding force, but also has the advantages of uniform coating, easy operation, and green environmental protection.

[0045] On the other hand, an embodiment of the present invention further provides a method for preparing a barium ferrite composite material, wherein the barium ferrite composite material is as described above.

[0046] See also Figure 1 The preparation method of the barium ferrite composite material comprises the following steps:

[0047] Step S1: Provide barium ferrite powder and a metal plating solution. The metal plating solution includes a metal salt selected from at least one of cuprate and silverate. The barium ferrite powder is used to provide a barium ferrite core.

[0048] Step S2: mixing barium ferrite powder and a metal plating solution, and plating a conductive shell layer on the surface of the barium ferrite core by a chemical plating process to prepare a barium ferrite composite material.

[0049] The preparation method of the barium ferrite composite material provided in the embodiments of the present invention utilizes an electroless plating process to deposit a metal layer on the surface of a barium ferrite core, thereby forming a barium ferrite composite material comprising a barium ferrite core and a conductive shell. This preparation method has the advantages of a relatively uniform conductive shell, easy control of the coating morphology and thickness, convenient operation, and minimal environmental pollution.

[0050] For step S1 , the average particle size of the barium ferrite powder used is 1.0 um-2.5 um, including but not limited to: 1.0 um, 1.5 um, 2 um, 2.5 um, etc.

[0051] The embodiments of the present invention can use barium ferrite powder products sold in the art, or can be obtained by self-production.

[0052] In some examples, barium ferrite powder can be prepared by the following chemical coprecipitation method to obtain barium ferrite powder with uniform particle size, which includes the following steps:

[0053] Step S11: Evenly mix the barium metal salt, the iron metal salt and the alkaline solution, and then perform a hydrothermal reaction.

[0054] Step S12: centrifuging, washing, and drying the product system in sequence to obtain a barium ferrite precursor.

[0055] Step S13: calcining the barium ferrite precursor to obtain barium ferrite powder.

[0056] For step S11 , some applicable barium metal salts include but are not limited to at least one of barium chloride and barium nitrate, and some applicable iron metal salts include but are not limited to at least one of ferric citrate, ferric chloride, ferric sulfate, and ferric nitrate.

[0057] In some examples, the amounts of the barium metal salt and the iron metal salt are such that the molar ratio of barium to iron is 1:9-12, including but not limited to 1:9, 1:10, 1:11, 1:12, etc.

[0058] The mass ratio of the barium metal salt to the iron metal salt can be determined based on the molar ratio of barium to iron and the specific types of the iron metal salt and the barium metal salt.

[0059] The amount of barium metal salt is slightly excessive relative to its theoretical value to ensure that the reaction proceeds thoroughly, which is more conducive to obtaining pure phase barium ferrite. In this way, when the barium ferrite composite material is used to prepare lithium ion batteries, the electrochemical performance of the lithium ion battery is more excellent.

[0060] Some suitable alkaline solutions contain strong bases including, but not limited to, at least one of potassium hydroxide and sodium hydroxide.

[0061] In some examples, the mass ratio of the strong base contained in the alkaline solution to the iron metal salt is 5 to 10:1, including but not limited to 5:1, 5.5:1, 5.8:1, 6:1, 6.1:1, 6.2:1, 6.3:1, 6.4:1, 6.5:1, 6.6:1, 6.7:1, 6.8:1, 6.9:1, 7:1, etc.

[0062] In some examples, for the alkaline solution, the mass of the strong base is 1g-3g per 10mL of deionized water, which includes but is not limited to 1g, 1.1g, 1.2g, 1.3g, 1.4g, 1.5g, 1.6g, 1.7g, 1.8g, 1.9g, 2g, 2.1g, 2.2g, 2.3g, 2.4g, 2.5g, 3g, etc.

[0063] In some examples, a strong base can be added to deionized water and stirred magnetically to obtain an alkaline solution.

[0064] In some examples, the barium metal salt, the iron metal salt, and the alkaline solution are mixed uniformly and then subjected to a hydrothermal reaction, including:

[0065] Add barium metal salt and iron metal salt to the alkaline solution, stir until uniformly mixed, and obtain a mixed raw material liquid. Transfer the mixed raw material liquid to a reactor (preferably a high-pressure reactor) to carry out a hydrothermal reaction.

[0066] In some examples, the hydrothermal treatment temperature is 180°C-200°C and the hydrothermal time is 20h-24h to ensure that the reaction is sufficiently complete to obtain the desired product BaFe 12 O 19 Material.

[0067] The temperature of the hydrothermal treatment includes but is not limited to 180°C, 185°C, 190°C, 195°C, 200°C, etc., and the time of the hydrothermal treatment includes but is not limited to 20h, 21h, 22h, 23h, 24h, etc.

[0068] In step S12, the product system is centrifuged, washed, and dried in sequence to obtain a barium ferrite precursor, wherein the washing process includes but is not limited to sequential water washing and alcohol washing processes. The drying process can be performed in a vacuum drying oven to remove moisture from the barium ferrite precursor material. For example, the drying temperature can be 70° C. to 10° C., and the drying time can be 5 hours to 24 hours.

[0069] Step S13, calcining the barium ferrite precursor to obtain barium ferrite powder, includes placing the barium ferrite precursor in a muffle furnace, heating it to a calcination temperature, and then calcining it. After the calcination is completed, cooling it to room temperature to obtain barium ferrite powder.

[0070] In some examples, the calcination temperature is 700°C-1000°C, including but not limited to 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, etc.

[0071] In some examples, the calcination time is 2 hours to 10 hours, including but not limited to 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0072] In some examples, before calcining the barium ferrite precursor, the barium ferrite precursor is ground to prevent the barium ferrite precursor from agglomerating, thereby facilitating the acquisition of barium ferrite particles with good dispersion.

[0073] In step S2, barium ferrite powder and a metal plating solution are mixed to prepare a barium ferrite composite material through a chemical plating process, which includes:

[0074] The mixed solution of barium ferrite powder and metal plating solution is stirred at 20-30° C., and when the mixed solution is clear, the stirring is stopped, and the product system is centrifuged, washed, and dried in sequence to obtain a barium ferrite composite material.

[0075] The washing mentioned above may be water washing. The drying process mentioned above may be carried out in a vacuum drying oven to remove moisture from the barium ferrite composite material. For example, the drying time may be 5 hours to 10 hours.

[0076] In some examples, the formula of the metal plating solution suitable for embodiments of the present invention is as follows: metal salt 1g / L-10g / L, sodium hydroxide 1g / L-12g / L, formaldehyde 3ml / L-27ml / L, potassium sodium tartrate 3g / L-50g / L.

[0077] That is to say, the formula of the metal plating solution can also be as follows: metal salt 0.05g / 50ml-0.5g / 50ml, sodium hydroxide 0.05g / 50ml-0.6g / 50ml, formaldehyde 0.15ml / 50ml-1.35ml / 50ml, potassium sodium tartrate 0.15g / 50ml-2.5g / 50ml.

[0078] It can be understood that the metal plating solution also includes a balance of solvent, which can be water.

[0079] For example, the concentration of the metal salt in the metal plating solution includes but is not limited to 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, etc.

[0080] The concentration of sodium hydroxide in the metal plating solution includes but is not limited to 1g / L, 2g / L, 3g / L, 4g / L, 5g / L, 6g / L, 7g / L, 8g / L, 9g / L, 10g / L, 11g / L, 12g / L, etc.

[0081] The concentration of formaldehyde in the metal plating solution includes but is not limited to 3ml / L, 4ml / L, 5ml / L, 6ml / L, 7ml / L, 8ml / L, 9ml / L, 10ml / L, 11ml / L, 12ml / L, 13ml / L, 14ml / L, 15ml / L, 20ml / L, 25ml / L, 27ml / L, etc.

[0082] The concentration of potassium sodium tartrate in the metal plating solution includes but is not limited to 3g / L, 4g / L, 5g / L, 6g / L, 7g / L, 8g / L, 9g / L, 10g / L, 15g / L, 16g / L, 17g / L, 18g / L, 19g / L, 20g / L, 21g / L, 22g / L, 23g / L, 24g / L, 25g / L, 28g / L, 30g / L, 32g / L, 35g / L, 37g / L, 40g / L, 45g / L, 50g / L, etc.

[0083] In some examples, the metal salt can be a metal sulfate, chloride, basic carbonate, tartrate, acetate, etc., and the metal involved here can be copper or silver. For example, the metal salt can be copper sulfate, silver sulfate, etc.

[0084] Metal salts serve as the primary salt to provide the metal coating. Potassium sodium tartrate acts as a complexing agent to stabilize the metal ions and control the reaction rate. Sodium hydroxide maintains the pH of the metal plating solution to allow formaldehyde to fully exert its reducing effect. Formaldehyde reduces the metal ions to the elemental metal to form the metal coating.

[0085] In some examples, the mass ratio of barium ferrite powder to metal salt is 1:0.5-5, thereby forming a conductive shell layer of a certain thickness on the outer surface of the barium ferrite core. The mass ratio of barium ferrite powder to metal salt includes but is not limited to 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, etc.

[0086] In another aspect, an embodiment of the present invention further provides a use of any of the above-mentioned barium ferrite composite materials in the preparation of a lithium-ion battery.

[0087] The barium ferrite composite material provided by the embodiment of the present invention can be used as an electrode material due to its good electrical conductivity, for example, as a negative electrode material of a lithium ion battery, and endows the lithium ion battery with excellent charge and discharge performance and rate performance.

[0088] As an expanded application, the barium ferrite composite material provided by the embodiment of the present invention can also be used in the catalytic field as a catalyst, used as an electrode material in supercapacitors, used as a photoelectric material, and so on.

[0089] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. In the examples, if specific techniques or conditions are not specified, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially. In the following examples, if not clearly stated, "%" refers to weight percentage.

[0090] Example 1

[0091] This embodiment 1 provides a barium ferrite composite material, which includes a barium ferrite core and a conductive shell layer coated on the outside of the barium ferrite core, wherein the conductive shell layer is a copper layer.

[0092] The barium ferrite composite material is prepared by the following method:

[0093] Step 1: Dissolve 6g of potassium hydroxide in 30ml of water to obtain an alkaline solution. Add 0.12g of barium chloride and 1g of ferric chloride (corresponding to a molar ratio of Ba to Fe of 1:10) to the alkaline solution and stir until uniformly mixed to obtain a mixed raw material solution. Transfer the mixed raw material solution to an autoclave for hydrothermal reaction. The hydrothermal treatment temperature is 180°C and the hydrothermal time is 24h.

[0094] Step 2: Centrifuge, wash, and dry the product system in sequence to obtain a barium ferrite precursor. The washing process includes sequentially washing with water and washing with alcohol. The drying process is performed in a vacuum drying oven at 90° C. for 12 hours.

[0095] Step 3: Grind the barium ferrite precursor, place the ground barium ferrite precursor in a muffle furnace, heat it to 900° C., calcine it for 3 hours, and cool it to room temperature to obtain barium ferrite powder.

[0096] Step 4: Stirring a mixture of 0.2 g of barium ferrite powder and the metal plating solution at 25° C., stopping stirring when the mixed solution becomes clear, and centrifuging, washing, and drying the mixture in sequence to obtain a barium ferrite composite material. The drying process is performed in a vacuum drying oven at 50° C. for 12 hours.

[0097] The metal plating solution is as follows: 0.3g / 50ml of CuSO4·5H2O, 0.9g / 50ml of KNaC4H4O6, 0.3g / 50ml of NaOH and 0.9ml / 50ml of HCHO, that is, 0.3g of CuSO4·5H2O, 0.9g of KNaC4H4O6, 0.3g of NaOH and 0.9ml of HCHO are dissolved in 50ml of water.

[0098] Example 2

[0099] This embodiment 2 provides a barium ferrite composite material, which includes a barium ferrite core and a conductive shell layer coated on the outside of the barium ferrite core, wherein the conductive shell layer is a copper layer.

[0100] The barium ferrite composite material is prepared by the following method:

[0101] Prepare barium ferrite powder. The preparation method is shown in Example 1.

[0102] A mixture of 0.2 g of barium ferrite powder and a metal plating solution was stirred at 25° C. When the mixed solution became clear, stirring was stopped, and the mixture was centrifuged, washed with water, and dried in a vacuum drying oven at 50° C. for 12 hours to obtain a barium ferrite composite material.

[0103] The metal plating solution is as follows: 0.05g / 50ml of CuSO4·5H2O, 0.15g / 50ml of KNaC4H4O6, 0.05g / 50ml of NaOH and 0.15ml / 50ml of HCHO, that is, 0.05g of CuSO4·5H2O, 0.15g of KNaC4H4O6, 0.05g of NaOH and 0.15ml of HCHO are dissolved in 50ml of water.

[0104] Example 3

[0105] This embodiment 3 provides a barium ferrite composite material, which includes a barium ferrite core and a conductive shell layer coated on the outside of the barium ferrite core, wherein the conductive shell layer is a copper layer.

[0106] The barium ferrite composite material is prepared by the following method:

[0107] Prepare barium ferrite powder. The preparation method is shown in Example 1.

[0108] A mixture of 0.2 g of barium ferrite powder and a metal plating solution was stirred at 25° C. When the mixed solution became clear, stirring was stopped, and the mixture was centrifuged, washed with water, and dried in a vacuum drying oven at 50° C. for 12 hours to obtain a barium ferrite composite material.

[0109] The metal plating solution is as follows: 0.1g / 50ml of CuSO4·5H2O, 0.3g / 50ml of KNaC4H4O6, 0.1g / 50ml of NaOH and 0.45ml / 50ml of HCHO, that is, 0.1g of CuSO4·5H2O, 0.3g of KNaC4H4O6, 0.1g of NaOH and 0.45ml of HCHO are dissolved in 50ml of water.

[0110] Example 4

[0111] This embodiment 4 provides a barium ferrite composite material, which includes a barium ferrite core and a conductive shell layer coated on the outside of the barium ferrite core, wherein the conductive shell layer is a copper layer.

[0112] The barium ferrite composite material is prepared by the following method:

[0113] Prepare barium ferrite powder. The preparation method is shown in Example 1.

[0114] A mixture of 0.2 g of barium ferrite powder and a metal plating solution was stirred at 25° C. When the mixed solution became clear, stirring was stopped, and the mixture was centrifuged, washed with water, and dried in a vacuum drying oven at 50° C. for 12 hours to obtain a barium ferrite composite material.

[0115] The metal plating solution is as follows: 0.2 g / 50 ml of CuSO4.5H2O, 0.6 g / 50 ml of KNaC4H4O6, 0.2 g / 50 ml of NaOH, and 0.45 ml / 50 ml of HCHO. That is, 0.2 g of CuSO4.5H2O, 0.6 g of KNaC4H4O6, 0.2 g of NaOH, and 0.45 ml of HCHO are dissolved in 50 ml of water.

[0116] Test Example 1

[0117] In this test example 1, the surface morphology of the barium ferrite powder and the barium ferrite composite material prepared in Example 1 was observed using a Zeiss Supra55 scanning electron microscope. Figure 1 Figures a and b are SEM images of barium ferrite powder. Figure 1 Figures c and d are SEM images of barium ferrite composite materials.

[0118] Figure 1 The hexagonal sheet structure in is the desired barium ferrite structure, Figure 1It can be seen that Example 1 successfully prepared an ideal hexagonal barium ferrite core, and successfully plated a copper layer on the barium ferrite core as a conductive shell layer. The presence of the copper layer has no obvious effect on the structure of the barium ferrite core, which indicates that the copper layer is uniformly plated on the surface of the barium ferrite core.

[0119] Figure 2 This is a characterization atlas of the barium ferrite composite material provided in Example 1. Various test images are grouped together for easy observation and comparison. This test example 1 also uses a Jeol JEM-2100F transmission electron microscope to test the crystal structure of the barium ferrite composite material prepared in Example 1. The test structure is shown in Figure 2 Figure a, Figure b and Figure c in the figure, where Figure 2 Figure a shows an electron microscope image of a barium ferrite composite material at a 200nm scale. Figure 2 Figure b shows an electron microscope image of a barium ferrite composite material at a 5nm scale. Figure 2 Figure c shows an electron microscope image of a barium ferrite composite material at a 100nm scale.

[0120] Further, Figure 2 The lattice spacing measured after Fourier transformation of the high-resolution image corresponding to Figure b is 0.294nm, which corresponds to the hexagonal BaFe 12 O 19 (110) crystal plane, it can be seen that the internal lattice spacing of the barium ferrite composite material is the same as the lattice spacing of the barium ferrite material. The surface copper layer is successfully coated on the outer surface of the barium ferrite core without affecting the internal structure of the barium ferrite core.

[0121] In this embodiment 1, an energy dispersive X-ray spectrometer (EDX) was used to perform EDX testing on the barium ferrite composite material prepared in embodiment 1. The obtained EDX spectrum is shown in FIG. Figure 2 From Figure d in the figure, we can see that copper element exists in the barium ferrite composite material, and the copper layer is successfully coated on the outer surface of the barium ferrite core.

[0122] This embodiment 1 also tests the barium ferrite composite material prepared in embodiment 1 through TEM images and corresponding element mapping images, wherein, Figure 2 Figures f, g, h, and i in the figure respectively illustrate the distribution of barium, iron, oxygen, and copper elements. It can be seen that the above elements are evenly distributed in the barium ferrite composite material, which also shows that the copper layer is evenly plated on the surface of the material.

[0123] In this test example 1, the barium ferrite powder prepared in Example 1 was also tested using a Bruker D8 Advance X-ray diffractometer. At the same time, the same test was performed on the barium ferrite powder corresponding to the molar ratio of Ba to Fe when the content ratio of the barium metal salt and the iron metal salt was 1:9, 1:11 and 1:12.

[0124] Test results see Figure 3 ,like Figure 3 As shown in FIG, the barium ferrite sample has obvious characteristic peaks at 2θ=30.8°, 32.2°, 34.1°, 37.0°, 40.3°, 42.4°, 55.0°, 56.3°, 63.0°, etc., and when the content ratio of the barium metal salt and the iron metal salt is such that the molar ratio of Ba to Fe is 1:11, the characteristic peaks of the prepared barium ferrite and BaFe 12 O 19 The characteristic peaks of the standard card (PDF#43-0002) are consistent, and the barium ferrite basically does not contain any unwanted impurities. The corresponding crystal planes of the barium ferrite are 110, 107, 114, 203, 205, 206, 217, 304, and 220, respectively.

[0125] In this test example 1, the barium ferrite composite materials prepared in Examples 1 to 4 were also tested using a Bruker D8 Advance X-ray diffractometer (wherein BFO-Cu4 corresponds to the barium ferrite composite material of Example 1, BFO-Cu1 corresponds to the barium ferrite composite material of Example 2, BFO-Cu2 corresponds to the barium ferrite composite material of Example 3, BFO-Cu3 corresponds to the barium ferrite composite material of Example 4, and BFO corresponds to a pure phase barium ferrite material). The test results are shown in FIG. Figure 4 ,like Figure 4 As shown, the presence of copper element was detected in the barium ferrite composite materials corresponding to Examples 1 to 4, proving that the copper element was successfully doped.

[0126] Test Example 2

[0127] In this test example 2, the barium ferrite composite materials prepared in Examples 1 to 4 were made into electrode sheets and assembled into lithium-ion batteries. The specific production process is as follows:

[0128] The barium ferrite composite material, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were weighed into a 5 ml test tube in a mass ratio of 7:2:1, and N-methyl-2-pyrrolidone (NMP) was added dropwise thereto and mixed and stirred to obtain the electrode negative material.

[0129] Because barium ferrite composites are magnetic, the mixed electrode materials are first mechanically stirred for 1 hour, then ultrasonically stirred for 30 minutes, alternating these steps until a pure battery negative electrode material is obtained. The battery negative electrode material is coated onto copper foil using a 200μm coater, vacuum-dried at 100°C for 12 hours, and finally cut into circular negative electrode sheets with a diameter of 12mm using a slicer.

[0130] In a glove box filled with argon and with water and oxygen concentrations controlled below 0.1 ppm, the cathode and anode sheets were assembled into button cells in the order of cathode shell, anode sheet, separator, lithium sheet, nickel mesh, and anode shell. The electrolyte was a commercial 1MLIPF6 / EC+DMC solution (1:1 volume ratio).

[0131] In this test example 2, a BTS-3000 battery tester produced by Shenzhen Xinweier Electronics Co., Ltd. was used to perform constant current charge and discharge and rate performance tests on the lithium-ion battery based on the barium ferrite composite material of Example 1 at room temperature.

[0132] The test results show that the lithium-ion battery based on the barium ferrite composite material of Example 1 has a high -1 At a current density of 0.1A·g, the discharge capacity of the lithium-ion battery remains at 746.6mAh·1 after 850 cycles. -1 , 0.2A·g -1 , 0.4A·g -1 , 0.8A·g -1 , 1.0A·g -1 , 1.6A·g -1 , 3.2A·g -1 and 5.0A·g -1 When the discharge capacity of lithium-ion batteries is 996 mAh g -1 , 944mAh·g -1 , 772mAh·g -1 , 604mAh·g -1 , 508mAh·g -1 , 400mAh·g -1 , 232mAh·g -1 and 134mAh·g -1 .

[0133] When the current density returned to 0.1 A g -1 The discharge capacity of the lithium-ion battery can reach 1035mAh·g -1 (See Figure 5 ), it can be seen that the lithium-ion battery exhibits excellent cycle and rate performance.

[0134] In this test example 2, the impedance performance of the lithium-ion battery assembled with the barium ferrite powder (BFO) and the barium ferrite composite material (Cu-BFO) provided in Example 1 was also tested. The test results are shown in Figure 6 ,Depend on Figure 6 It can be seen that the electrical conductivity of the barium ferrite composite material is significantly improved compared with the barium ferrite powder, thereby making it exhibit better electrochemical performance and cycle performance.

[0135] According to the same test, the electrochemical performance and cycle performance of the lithium ion battery based on the barium ferrite composite material of Examples 2-3 are slightly inferior to those of the lithium ion battery based on the barium ferrite composite material of Example 1, but also show excellent electrochemical performance and cycle performance.

[0136] The above description is only for the purpose of facilitating those skilled in the art to understand the technical solution of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A barium ferrite composite material, characterized in that: The barium ferrite composite material is used as a negative electrode material for lithium-ion batteries, and the barium ferrite composite material includes a barium ferrite core and a conductive shell layer coated on the outside of the barium ferrite core; The conductive shell layer is made of at least one material selected from copper, silver, and gold; The barium ferrite core is composed of barium ferrite BaFe 12 O 19 Material composition; The average particle size of the barium ferrite core is 1.0um-2.5um, and the thickness of the conductive shell is 5mm-15mm.

2. The barium ferrite composite material according to claim 1, characterized in that The conductive shell layer is a copper layer.

3. A method for preparing a barium ferrite composite material, characterized in that: The barium ferrite composite material is as described in any one of claims 1-2; The preparation method of the barium ferrite composite material comprises: Providing barium ferrite powder and a metal plating solution, wherein the metal plating solution includes a metal salt, and the metal salt is selected from at least one of cuprate, silverate, and gold salt; Mixing the barium ferrite powder and the metal plating solution, and plating a conductive shell layer on the surface of the barium ferrite core by a chemical plating process to prepare the barium ferrite composite material; The barium ferrite powder is prepared by the following method: The barium metal salt, the iron metal salt and the alkaline solution are uniformly mixed, and then subjected to a hydrothermal reaction, wherein the amounts of the barium metal salt and the iron metal salt are such that the molar ratio of barium to iron is 1:9-12; The product system is centrifuged, washed and dried in sequence to obtain a barium ferrite precursor; The barium ferrite precursor is calcined to obtain the barium ferrite powder.

4. The method for preparing the barium ferrite composite material according to claim 3, wherein: The barium ferrite composite material is prepared by mixing the barium ferrite powder and the metal plating solution and plating a conductive shell layer on the surface of the barium ferrite core by a chemical plating process, comprising: The mixed solution of the barium ferrite powder and the metal plating solution is stirred at 20° C.-30° C., and when the mixed solution is in a clear state, the stirring is stopped, and the product system is centrifuged, washed, and dried in sequence to obtain the barium ferrite composite material.

5. The method for preparing the barium ferrite composite material according to claim 3, wherein: The metal plating solution comprises: 1g / L-10g / L of metal salt, 1g / L-12g / L of sodium hydroxide, 3ml / L-27ml / L of formaldehyde, and 3g / L-50g / L of potassium sodium tartrate.

6. The method for preparing the barium ferrite composite material according to claim 3, wherein: The mass ratio of the barium ferrite powder to the metal salt is 1:0.5-5.

7. The method for preparing the barium ferrite composite material according to claim 3, wherein: The temperature of the hydrothermal treatment is 180° C.-200° C., and the hydrothermal time is 20 h-24 h.

8. Use of the barium ferrite composite material according to any one of claims 1 to 2 in the preparation of lithium-ion batteries.

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