A Co-Sb composite hard carbon material, its preparation method, negative electrode sheet, and applications.

Abstract

This invention relates to the field of battery anode material technology, specifically to Co-Sb composite hard carbon materials, their preparation methods, anode sheets, and applications. The method first combines a Co source and an Sb source to obtain a Co-Sb material. Then, based on the Co-Sb material as a core, organic carbon is deposited and coated, and finally carbonized to obtain the Co-Sb composite hard carbon material. This method is simple and easy to implement. Combining the electrocatalytically active Co element with Sb, and then combining it with carbon materials, is beneficial for the anode material to produce excellent electrochemical performance. As an anode material, this material can improve the problem of limited capacity in anode materials, enhance its reversible capacity, and simultaneously maintain excellent stability and good fast-charge and fast-discharge capabilities during charge-discharge cycles, thereby improving the overall electrical performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery anode material technology, and more specifically, to Co-Sb composite hard carbon materials, their preparation methods, anode sheets, and applications. Background Technology

[0002] Hard carbon, as a battery anode material, exhibits excellent cycle stability, but its theoretical specific capacity is limited, posing a significant challenge to further improving battery energy density. Compared to hard carbon anode materials, alloy anode materials have a significant advantage in theoretical specific capacity. These include P, Sn, Sb, Pb, and Bi-based materials, covering a wide range of fields and offering substantial potential for improvement. However, these anode materials suffer from poor cycle stability due to significant volume expansion during charge and discharge. Furthermore, the synthesis conditions for P and Sn alloys are demanding, Pb is a heavy metal with potential adverse effects on human health, and Bi-based materials have a relatively low theoretical specific capacity among these materials. Therefore, developing Sb-based materials with high capacity, excellent fast charging and discharging capabilities, and superior cycle stability holds considerable promise.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] The primary objective of this invention is to provide a method for preparing Co-Sb composite hard carbon materials. This method involves first combining a Co source and an Sb source to obtain a Co-Sb material, then depositing and coating organic carbon onto the Co-Sb material as a core, and finally carbonizing it to obtain the Co-Sb composite hard carbon material. This method is simple and easy to implement. Combining the electrocatalytically active Co element with Sb and then combining it with carbon materials is beneficial for the anode material to produce excellent electrochemical performance.

[0005] The second objective of this invention is to provide a Co-Sb composite hard carbon material, which, as a negative electrode material, can improve the problem of limited capacity of negative electrode materials, enhance its reversible capacity, and at the same time, it still has excellent stability and good fast charging and discharging capability during charge and discharge cycles.

[0006] A third objective of this invention is to provide a negative electrode sheet comprising the Co-Sb composite hard carbon material as described above, which can be used in power batteries, including but not limited to lithium-ion batteries and sodium-ion batteries, and can improve the overall electrochemical performance of the battery.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] A method for preparing a Co-Sb composite hard carbon material includes the following steps:

[0009] (a) Mix and stir a Co source, an Sb source and a complexing agent to obtain a Co-Sb precursor, and dry and calcine the precursor to obtain a Co-Sb material;

[0010] (b) A surfactant, pH adjuster, phenolic compound and formaldehyde solution are added to the dispersion of the Co-Sb material, and the mixture is stirred to carry out the reaction. Then the solid part is washed, dried and calcined to obtain the Co-Sb composite hard carbon material. The phenolic compound includes catechol and / or resorcinol.

[0011] Preferably, in step (a), the Co source includes at least one of cobalt chloride, cobalt bromide, cobalt nitrate, cobalt acetate, cobalt carbonate, cobalt hydroxide, and cobalt oxide.

[0012] Preferably, in step (a), the Sb source comprises antimony chloride and / or antimony acetate.

[0013] Preferably, in step (a), the mass ratio of the Co source to the Sb source is 1:4 to 6.

[0014] Preferably, in step (a), the complexing agent includes at least one of ammonium hydroxide, ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium fluoride, ethylenediaminetetraacetic acid, ethylenediamine, methylamine, and dimethylamine.

[0015] Preferably, in step (a), the drying temperature is 180–220°C.

[0016] Preferably, in step (a), the drying time is 8 to 10 hours.

[0017] Preferably, in step (a), the calcination temperature is 600–800°C.

[0018] Preferably, in step (a), the calcination time is 6 to 8 hours.

[0019] Preferably, the heating rate of the calcination is 5-8°C / min.

[0020] Preferably, in step (b), the surfactant comprises at least one of hexadecyltrimethylammonium bromide, hexadecyldimethylammonium chloride, octadecyltrimethylammonium chloride, and dodecyldimethylamine oxide.

[0021] Preferably, in step (b), the pH adjuster includes at least one of ammonia, sodium carbonate, and sodium bicarbonate.

[0022] Preferably, in step (b), the amount of surfactant added is 0.06 to 0.1 mmol of surfactant per gram of Co-Sb material.

[0023] Preferably, in step (b), the amount of phenolic compound added is: 0.4 to 0.6 g of phenolic compound per gram of Co-Sb material.

[0024] Preferably, in step (b), 0.3 to 0.5 mL of the formaldehyde solution is added for every gram of the Co-Sb material:

[0025] Preferably, in step (b), the concentration of the formaldehyde solution is 13-14 mol / L.

[0026] Preferably, in step (b), the drying temperature is 70–80°C.

[0027] Preferably, in step (b), the drying is air drying.

[0028] Preferably, in step (b), the calcination temperature is 500–550°C.

[0029] Preferably, in step (b), the calcination time is 3 to 4 hours.

[0030] A Co-Sb composite hard carbon material is prepared by the above-mentioned method for preparing Co-Sb composite hard carbon material.

[0031] A negative electrode sheet comprising the aforementioned Co-Sb composite hard carbon material.

[0032] The application of the negative electrode sheet in sodium-ion batteries.

[0033] The application of the aforementioned negative electrode sheet in lithium-ion batteries.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) The preparation method of Co-Sb composite hard carbon material provided by the present invention is simple and easy to implement. The Co element with electrocatalytic effect is combined with Sb and then combined with carbon material, which is beneficial to the anode material to produce excellent electrochemical performance.

[0036] (2) The Co-Sb composite hard carbon material provided by the present invention can improve the problem of limited capacity of negative electrode material and enhance its reversible capacity. At the same time, it still has excellent stability and good fast charging and fast discharging capability during charge and discharge cycles.

[0037] (3) The negative electrode sheet of the Co-Sb composite hard carbon material provided by the present invention can be used in power batteries, including but not limited to lithium-ion batteries and sodium-ion batteries, and can improve the overall electrochemical performance of the battery. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 The X-ray diffraction pattern of the Co-Sb composite hard carbon material obtained in Example 1 of this invention;

[0040] Figure 2 The graph shows the cycle performance test results of the sodium-ion battery obtained in Example 7 of this invention.

[0041] Figure 3 The graph shows the rate performance test results of the sodium-ion battery obtained in Example 7 of this invention.

[0042] Figure 4 This is the AC impedance spectrum of the sodium-ion battery obtained in Example 7 of the present invention. Detailed Implementation

[0043] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0044] This invention provides a method for preparing a Co-Sb composite hard carbon material, comprising the following steps:

[0045] (a) Mix and stir a Co source, an Sb source and a complexing agent to obtain a Co-Sb precursor, and dry and calcine the precursor to obtain a Co-Sb material;

[0046] (b) Add surfactant, pH adjuster, phenolic compound and formaldehyde solution to the dispersion of Co-Sb material, stir to carry out reaction, and then wash, dry and calcine the solid part to obtain Co-Sb composite hard carbon material;

[0047] Phenolic compounds include, but are not limited to, catechol and / or resorcinol.

[0048] This invention first combines a Co source and an Sb source to obtain a Co-Sb material. Then, based on the Co-Sb material as a core, organic carbon is deposited and coated. Finally, the material is carbonized to obtain a Co-Sb composite hard carbon material. This method is simple and easy to implement. Combining the electrocatalytic element Co with Sb and then combining it with carbon material is beneficial for the anode material to produce excellent electrochemical performance.

[0049] In a preferred embodiment, the Co source, Sb source and complexing agent are first dissolved in a solvent, such as ethanol, and then mixed. During the mixing process, the solution can be heated appropriately, for example, to 40-50°C.

[0050] In a preferred embodiment, in step (a), the Co source can be conventionally selected from at least one of cobalt chloride, cobalt bromide, cobalt nitrate, cobalt acetate, cobalt carbonate, cobalt hydroxide, and cobalt oxide. A single Co source can be added, or a combination of several Co sources can be added, but it is not limited thereto.

[0051] In a preferred embodiment, the Sb source includes, but is not limited to, antimony chloride and / or antimony acetate.

[0052] In a preferred embodiment, the mass ratio of the Co source to the Sb source is 1:4 to 6, for example: any ratio or a range of any two ratios from 1:4, 1:4.2, 1:4.61, 1:4.8, 1:5, 1:5.2, 1:5.4, 1:5.6, 1:5.8, 1:6.

[0053] In a preferred embodiment, in step (a), the main function of the complexing agent is to promote the formation of Co-Sb material, including at least one of ammonium hydroxide, ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium fluoride, ethylenediaminetetraacetic acid, ethylenediamine, methylamine and dimethylamine, but not limited thereto.

[0054] In a preferred embodiment, in step (a), the drying temperature is 180–220°C, for example, any one or any two values ​​from 180°C, 190°C, 200°C, 210°C, and 220°C; the drying time is 8–10 hours, for example, any one or any two values ​​from 8 hours, 8.5 hours, 9 hours, 9.5 hours, and 10 hours. Preferably, the drying is air drying.

[0055] In a preferred embodiment, in step (a), the calcination temperature is 600–800°C, for example, any one value or a range of any two values ​​among 600°C, 650°C, 700°C, 750°C, and 800°C; the calcination time is 6–8 hours, for example, any one value or a range of any two values ​​among 6 hours, 6.5 hours, 7 hours, 7.5 hours, and 8 hours.

[0056] In a preferred embodiment, the heating rate of calcination is controlled at 5 to 8 °C / min, for example, any one value or a range of any two values ​​among 5 °C / min, 5.5 °C / min, 6 °C / min, 6.5 °C / min, 7 °C / min, 7.5 °C / min, and 8 °C / min.

[0057] In a preferred embodiment, in step (b), the surfactant is a cationic surfactant, including but not limited to at least one of hexadecyltrimethylammonium bromide, hexadecyldimethylammonium chloride, octadecyltrimethylammonium chloride, and dodecyldimethylamine oxide, but not limited thereto.

[0058] In a preferred embodiment, in step (b), the pH adjuster is used to adjust the pH value of the solution, including at least one of ammonia, sodium carbonate, and sodium bicarbonate, but not limited thereto.

[0059] In a preferred embodiment, in step (b), the amount of surfactant added is 0.06 to 0.1 mmol of surfactant per gram of the Co-Sb material.

[0060] In a preferred embodiment, in step (b), 0.4 to 0.6 g of the phenolic compound is added per gram of Co-Sb material, including any one value or a range of any two values ​​from 0.4 g, 0.42 g, 0.46 g, 0.48 g, 0.50 g, 0.54 g, 0.58 g, and 0.6 g.

[0061] In a preferred embodiment, in step (b), 0.6 to 0.8 mL of the formaldehyde solution is added per gram of Co-Sb material, for example, any one or any two values ​​from 0.6 mL, 0.68 mL, 0.7 mL, and 0.8 mL. The concentration of the formaldehyde solution is 13 to 14 mol / L, for example, any one or any two values ​​from 13.1 mol / L, 13.2 mol / L, 13.3 mol / L, 13.306 mol / L, 13.4 mol / L, 13.5 mol / L, 13.6 mol / L, 13.7 mol / L, 13.8 mol / L, 13.9 mol / L, and 14 mol / L.

[0062] In a preferred embodiment, in step (b), the drying temperature is 70 to 80°C, for example, any one value or a range of any two values ​​among 70°C, 72°C, 75°C, 78°C, and 80°C. Preferably, the drying is air drying.

[0063] In a preferred embodiment, in step (b), calcination carbonizes the organic carbon source at a temperature of 500–550°C, for example, any one or any two of the following values: 500°C, 510°C, 520°C, 530°C, and 550°C; and for a duration of 3–4 hours.

[0064] A Co-Sb composite hard carbon material is prepared by the above-mentioned preparation method of Co-Sb composite hard carbon material. As a negative electrode material, this material can improve the problem of limited capacity of negative electrode materials and enhance its reversible capacity. At the same time, it still has excellent stability and good fast charging and fast discharging capability during charge and discharge cycles.

[0065] A negative electrode sheet comprising the Co-Sb composite hard carbon material described above.

[0066] In a preferred embodiment, a negative electrode slurry is prepared by mixing Co-Sb composite hard carbon material, conductive agent, and binder, and then coated onto a current collector and dried to obtain a negative electrode sheet.

[0067] The application of negative electrode sheets in sodium-ion batteries can improve the overall electrochemical performance of sodium-ion batteries.

[0068] The application of negative electrode sheets in lithium-ion batteries can improve the overall electrochemical performance of lithium-ion batteries.

[0069] Example 1

[0070] (1) Dissolve 0.65g cobalt chloride, 3.0g antimony acetate and 1mL ethylenediamine in 5ml anhydrous ethanol respectively; the solution containing cobalt is light red and the other solutions are colorless; mix the three solutions after stirring for 1 hour, stir at room temperature for 24h, dry and calcine the precursor to obtain Co-Sb material;

[0071] The drying temperature is 200℃, specifically drying in static air at 200℃ for 8 hours, and then calcining in static air at a heating rate of 5℃ / min to 600℃ for 6 hours.

[0072] (2) 0.5g of sintered Co-Sb material was added to deionized water and ultrasonically dispersed for 30 minutes. Then, the mixture was stirred and heated to 50°C in a water bath. 3.0mL of 0.01mol / L hexadecyltrimethylammonium bromide solution, 0.50mL of 6.47mol / L ammonia water, 0.23g of resorcinol, and 0.34mL of 13.306mol / L formaldehyde solution were added. The mixture was slightly sealed with plastic wrap, stirred for 2 hours, centrifuged, washed once with water (about 80mL each time), and washed once with ethanol. The mixture was then transferred to a beaker and dried in air at 80°C to obtain the Co-Sb composite precursor. The Co-Sb composite precursor was calcined in H2 / Ar (1:9) at 500°C for 3 hours and cooled to room temperature to obtain the Co-Sb composite hard carbon material.

[0073] The Co-Sb composite hard carbon material obtained in Example 1 was subjected to X-ray diffraction testing using an X-ray diffractometer, and the results were obtained. Figure 1 It can be found that the Co-Sb composite hard carbon material prepared by the method provided in this invention has a better crystal form.

[0074] Example 2

[0075] (1) Dissolve 0.6g cobalt chloride, 3.6g antimony acetate and 1mL ethylenediamine in 5ml anhydrous ethanol respectively; the solution containing cobalt is light red and the other solutions are colorless; mix the three solutions after stirring for 1 hour, stir at room temperature for 24h, dry and calcine the precursor to obtain Co-Sb material;

[0076] The drying temperature is 180℃, specifically drying in static air at 180℃ for 10 hours, and then calcining in static air at a heating rate of 5℃ / min to 800℃ for 8 hours.

[0077] (2) 0.5g of sintered Co-Sb material was added to deionized water and ultrasonically dispersed for 30 minutes. Then, the mixture was stirred and heated to 50°C in a water bath. 5.0mL of 0.01mol / L hexadecyltrimethylammonium bromide solution, 0.45mL of 6.47mol / L ammonia water, 0.24g of resorcinol, and 0.4mL of 13.2mol / L formaldehyde solution were added. The mixture was slightly sealed with plastic wrap, stirred for 2 hours, centrifuged, washed once with water (about 80mL each time), and washed once with ethanol. The mixture was then transferred to a beaker and dried in air at 80°C to obtain the Co-Sb composite precursor. The Co-Sb composite precursor was calcined in H2 / Ar (1:9) at 550°C for 4 hours and cooled to room temperature to obtain the Co-Sb composite hard carbon material.

[0078] Example 3

[0079] (1) Same as step (1) in the embodiment.

[0080] (2) 0.5 g of sintered Co-Sb material was added to deionized water and ultrasonically dispersed for 30 minutes. Then, the mixture was stirred and heated to 50 °C in a water bath. 4.0 mL of 0.01 mol / L hexadecyltrimethylammonium bromide solution, 0.5 mL of 6.47 mol / L ammonia water, 0.25 g of resorcinol, and 0.34 mL of 13.2 mol / L formaldehyde solution were added. The mixture was slightly sealed with plastic wrap, stirred for 2 hours, centrifuged, washed once with water (approximately 80 mL each time), and washed once with ethanol. The mixture was then transferred to a beaker and dried in air at 70 °C to obtain the Co-Sb composite precursor. The Co-Sb composite precursor was calcined in H2 / Ar (1:9) at 520 °C for 3.5 hours and cooled to room temperature to obtain the Co-Sb composite hard carbon material.

[0081] Example 4

[0082] (1) Same as step (1) in the embodiment.

[0083] (2) 0.5 g of sintered Co-Sb material was added to deionized water and ultrasonically dispersed for 30 minutes. Then, the mixture was stirred and heated to 50 °C in a water bath. 3.0 mL of 0.01 mol / L hexadecyltrimethylammonium bromide solution, 0.5 mL of 6.47 mol / L ammonia water, 0.26 g of resorcinol, and 0.34 mL of 13.2 mol / L formaldehyde solution were added. The mixture was slightly sealed with plastic wrap, stirred for 2 hours, centrifuged, washed once with water (approximately 80 mL each time), and washed once with ethanol. The mixture was then transferred to a beaker and dried in air at 70 °C to obtain the Co-Sb composite precursor. The Co-Sb composite precursor was calcined in H2 / Ar (1:9) at 500 °C for 3 hours and cooled to room temperature to obtain the Co-Sb composite hard carbon material.

[0084] Example 5

[0085] The difference between Example 5 and Example 1 is that in step (1), the Co source is 0.5g cobalt nitrate and 2g antimony chloride, and the rest are the same.

[0086] Example 6

[0087] The difference between Example 6 and Example 1 is that in step (1), the drying temperature is 220°C, specifically drying in static air at 220°C for 9 hours, and then calcining at 700°C for 7 hours in static air at a heating rate of 8°C / min. The rest is the same.

[0088] Comparative Example 1

[0089] The difference between Comparative Example 1 and Example 1 is that the drying temperature in step (2) is 90°C and the calcination temperature is 600°C for 3 hours.

[0090] Comparative Example 2:

[0091] The difference between Comparative Example 2 and Example 1 is that the drying temperature in step (2) is 100°C and the calcination temperature is 700°C for 3 hours.

[0092] Comparative Example 3

[0093] The difference between Comparative Example 3 and Example 1 is that the drying temperature in step (2) is 110°C and the calcination temperature is 800°C for 3 hours.

[0094] Examples 7-12

[0095] 1) Grind and uniformly mix the active electrode material (from the Co-Sb composite hard carbon materials obtained in Examples 1-6) in a mass ratio of 70:20:10. Then, use a syringe to measure an appropriate amount of deionized water as a solvent to prepare the mixture into a slurry.

[0096] 2) Stir the mixture evenly on a magnetic stirrer for 8-10 hours, then coat the resulting slurry evenly onto copper foil, let the surface dry, and finally dry it overnight in a vacuum oven at 80°C to prepare the electrode sheet.

[0097] 3) A button cell, model 2032, was fabricated in a glove box filled with Ar. Glass fiber was used as the separator material, and hand-rolled sodium sheets served as both the counter electrode and the reference electrode. The electrolyte was 1 mol / L NaClO4 dissolved in a 1:1 volume ratio of ethylene carbonate and diethyl carbonate containing 5% by mass of fluoroethylene carbonate.

[0098] The diameter of the circular electrode sheet of the sodium-ion battery negative electrode material is 14 mm.

[0099] Comparative Examples 4-6 followed the method of Example 7, but replaced the negative electrode active material with the Co-Sb composite hard carbon material obtained in Comparative Examples 1-3.

[0100] Test case

[0101] Batteries were obtained using Examples 7-12 and Comparative Examples 4-6. The batteries assembled with electrode materials were tested using a Land battery testing system at 0.2 A·g. -1 Cyclic tests were conducted to measure its reversible capacity, coulombic cycle efficiency, and AC impedance. The results are shown in Table 1.

[0102] Table 1

[0103]

[0104] Through: SbCo + 3Na + +3e -→Na3Sb+Co. According to the alloying mechanism of negative electrode materials, 1 mol of SbCo reacts with sodium ions, resulting in 3 mol of electron transfer. Based on the theoretical capacity calculation formula: 96485*n / (M*3.6), the theoretical specific capacity of Sb-Co can be calculated to be 444.98 mAhg. -1 The battery made from the Co-Sb composite hard carbon material obtained in this application has a capacitance of 0.2 A·g. -1 Below, their reversible capacities are all greater than 400 mAh·g -1 The coulombic efficiency in subsequent cycles is close to 100%. Compared with the comparative example, this application shows better electrochemical performance in terms of reversible capacity and coulombic efficiency after 100 cycles.

[0105] Figure 2 The results for Example 7 are shown below. The upper line represents the cycle efficiency, and the lower line represents the discharge capacity. It can be observed that the reversible capacity is approximately 400 mAh·g. -1 The Coulomb efficiency for subsequent cycles is close to 100%. Figure 3 The rate performance test of Example 7 shows that even at 3.2 A·g -1 Its discharge capacity at a current density is approximately 250 mAh·g -1 This demonstrates that the negative electrode material prepared in this invention has fast discharge capability.

[0106] Figure 4 The AC impedance spectroscopy test of Example 7 shows that the charge transfer impedance of the negative electrode material prepared by the present invention is 600-635Ω, demonstrating the good conductivity of the electrode material. Although the charge transfer impedance of the comparative example is reduced, the content of Sb-Co active material is reduced due to the increased degree of carbonization (the drying and calcination temperature is higher than that of the example), so the reversible capacity is also reduced, which affects the electrochemical performance of the negative electrode.

[0107] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a Co-Sb composite hard carbon material, characterized in that, Includes the following steps: (a) The Co source, Sb source and complexing agent are mixed and stirred to obtain a Co-Sb precursor, and the precursor is dried and calcined to obtain a Co-Sb material; in step (a), the complexing agent includes at least one of ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium fluoride, ethylenediaminetetraacetic acid, ethylenediamine, methylamine and dimethylamine; In step (a), the mass ratio of the Co source to the Sb source is 1:4 to 6; In step (a), the calcination temperature is 600–800°C, and the calcination time is 6–8 hours; (b) A surfactant, pH adjuster, phenolic compound, and formaldehyde solution are added to the dispersion of the Co-Sb material, and the mixture is stirred to carry out the reaction. Then, the solid part is washed, dried, and calcined to obtain the Co-Sb composite hard carbon material. In step (b), the surfactant includes at least one of hexadecyltrimethylammonium bromide, hexadecyldimethylammonium chloride, octadecyltrimethylammonium chloride, and dodecyldimethylamine oxide. In step (b), the calcination temperature is 500–550°C. The phenolic compound includes catechol and / or resorcinol. In step (b), the pH adjuster includes at least one of ammonia, sodium carbonate, and sodium bicarbonate; In step (b), the amount of surfactant added is 0.06 to 0.1 mmol of surfactant per gram of Co-Sb material.

2. The preparation method of the Co-Sb composite hard carbon material according to claim 1, characterized in that, In step (a), the Co source includes at least one of cobalt chloride, cobalt nitrate, cobalt bromide, cobalt acetate, cobalt carbonate, cobalt hydroxide, and cobalt oxide.

3. The method for preparing Co-Sb composite hard carbon material according to claim 1, characterized in that, In step (a), the Sb source includes antimony chloride and / or antimony acetate.

4. The method for preparing Co-Sb composite hard carbon material according to claim 1, characterized in that, In step (a), at least one of the following features (1) to (3) is included: (1) The drying temperature is 180-220℃; (2) The drying time is 8-10 hours; (3) The heating rate of the calcination is 5 to 8 °C / min.

5. The method for preparing Co-Sb composite hard carbon material according to claim 1, characterized in that, In step (b), at least one of the following features (1) to (3) is included: (1) The amount of the phenolic compound added is: 0.4 to 0.6 g of the phenolic compound per gram of the Co-Sb material; (2) For every gram of the Co-Sb material, add 0.6 to 0.8 mL of the formaldehyde solution; (3) The concentration of the formaldehyde solution is 13-14 mol / L.

6. The method for preparing Co-Sb composite hard carbon material according to claim 1, characterized in that, In step (b), at least one of the following features (1) to (3) is included: (1) The drying temperature is 70-80℃; (2) The drying process is air drying; (3) The calcination time is 3 to 4 hours.

7. A Co-Sb composite hard carbon material, characterized in that, It is prepared by the method for preparing a Co-Sb composite hard carbon material as described in any one of claims 1-6.

8. A negative electrode sheet, characterized in that, Including the Co-Sb composite hard carbon material as described in claim 7.

9. The application of the negative electrode sheet as described in claim 8 in a sodium-ion battery.

10. The application of the negative electrode sheet as described in claim 8 in a lithium-ion battery.

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