Vacuum gas-phase-filled high-first-effect hard carbon material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of sodium ion batteries, and particularly relates to a vacuum gas phase filled high-first-effect hard carbon material and a preparation method and application thereof. The preparation method of the vacuum gas phase filled high-first-effect hard carbon material comprises the following steps: (1) mixing a biomass material and water, carrying out hydrothermal reaction, and after the hydrothermal reaction is finished, carrying out solid-liquid separation and washing to obtain an intermediate; (2) mixing and stirring the intermediate and a hydrochloric acid solution, carrying out solid-liquid separation, and cleaning the obtained solid with clear water until the pH is neutral to obtain a purified intermediate; (3) placing the purified intermediate in a first quartz boat, and placing a gas-phase filling material in a second quartz boat; the gas-phase filling material is alcohol and / or hydrocarbon; and (4) placing the first quartz boat and the second quartz boat in a tubular furnace, and calcining under a vacuum condition to obtain the vacuum gas phase filled high-first-effect hard carbon material. According to the method disclosed by the invention, the hard carbon material with high first-circle coulombic efficiency can be prepared at a relatively low temperature, and the preparation cost of the hard carbon material can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion batteries, and in particular relates to a vacuum gas phase filled high initial efficiency hard carbon material and a preparation method and application thereof. Background Art

[0002] As the country vigorously supports the development of new energy, limited lithium resources cannot meet the needs of today's social development, so there is an urgent need to find a substitute for lithium-ion batteries. Sodium-ion batteries are considered to be a substitute for lithium-ion batteries because of their abundant sodium resources and similar electrochemical properties to lithium-ion batteries. However, traditional commercial graphite anodes cannot be used in sodium-ion batteries. Therefore, it is urgent to develop a negative electrode material suitable for sodium-ion batteries.

[0003] Hard carbon materials are considered to be ideal negative electrode materials for sodium ion batteries because of their good conductivity, stability, and suitability for sodium ion embedding. Hard carbon materials face the problem of low first-cycle coulombic efficiency. At present, the effective method for preparing high first efficiency is carbonization preparation at a higher calcination temperature (≥1000°C). Although the first efficiency of hard carbon materials prepared by high-temperature calcination is improved, the energy consumption is increased, resulting in higher synthesis costs. For example, in the technical solution disclosed in patent document CN119176545 A, when preparing hard carbon materials, it requires high-temperature (≥1000°C) calcination twice.

[0004] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a vacuum gas-filled high first-efficiency hard carbon material and its preparation method and application, so as to help solve or improve the problem in the prior art that carbonization at a higher calcination temperature is required to improve the first-cycle coulomb efficiency of the hard carbon material, but the higher calcination temperature will cause high energy consumption.

[0006] In order to achieve the above-mentioned object, the present invention provides the following technical scheme: a method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material, comprising the following steps: (1) mixing a biomass material and water for a hydrothermal reaction, and after the hydrothermal reaction, performing solid-liquid separation, washing, and obtaining an intermediate; (2) mixing the intermediate with a hydrochloric acid solution, performing solid-liquid separation, and washing the obtained solid with clean water until the pH is neutral to obtain a purified intermediate; (3) placing the purified intermediate in a first quartz boat, and placing a vapor-filled material in a second quartz boat; the vapor-filled The material is alcohol and / or hydrocarbon; (4) placing the first quartz boat and the second quartz boat in a tubular furnace and calcining them under vacuum conditions to obtain the vacuum vapor-filled high-first-efficiency hard carbon material; in step (4), the tubular furnace has an air inlet and an air outlet, and the second quartz boat and the first quartz boat are sequentially arranged between the air inlet and the air outlet, and nitrogen and / or rare gas are introduced into the tubular furnace through the air inlet to replace the atmosphere in the tubular furnace, and the vacuum condition of the tubular furnace during the calcination process is maintained by connecting a vacuum device to the air outlet.

[0007] Preferably, in step (1), the temperature of the hydrothermal reaction is 100-250° C., and the time of the hydrothermal reaction is 1-48 h.

[0008] Preferably, in step (4), the calcination temperature is 800-1600° C., and the calcination time is 1-24 h.

[0009] Preferably, in step (4), the vacuum degree of the tubular furnace during calcination is P, -0.1 MPa≤P<0 MPa.

[0010] Preferably, the biomass material is charcoal and / or tea oil shell.

[0011] Preferably, the gas phase filling material is alcohol; the alcohol is selected from at least one of methanol, ethanol, ethylene glycol, propanol, butanol, glycerol, cyclohexanehexol, benzyl alcohol, pentanol, hexanol and octanol; the gas phase filling material is hydrocarbon; the hydrocarbon is selected from at least one of coal tar, paraffin oil, alkane, olefin, alkyne, alicyclic hydrocarbon and aromatic hydrocarbon.

[0012] The present invention also provides a vacuum gas phase filled high initial efficiency hard carbon material, which adopts the following technical scheme: a vacuum gas phase filled high initial efficiency hard carbon material, the vacuum gas phase filled high initial efficiency hard carbon material is prepared by the method as described above.

[0013] The present invention also provides a negative electrode, which adopts the following technical solution: a negative electrode, wherein the negative electrode contains the vacuum gas phase filled high first efficiency hard carbon material as described above.

[0014] The present invention also provides a battery, which adopts the following technical solution: a battery, the battery containing the vacuum gas phase filled high first efficiency hard carbon material as described above or the negative electrode as described above.

[0015] Beneficial effects:

[0016] The preparation method of the vacuum gas phase filled high first efficiency hard carbon material of the present invention can effectively reduce the specific surface area of ​​the hard carbon material, increase the graphitized structure of the hard carbon material, and improve the first cycle coulomb efficiency of the hard carbon material.

[0017] The method for preparing a vacuum gas phase filled high first efficiency hard carbon material of the present invention has a simple process and can realize the preparation of a hard carbon material with a high first cycle coulombic efficiency at a relatively low temperature, thereby effectively reducing the preparation cost of the hard carbon material.

[0018] When the vacuum gas phase filled high first efficiency hard carbon material of the present invention is calcined at a temperature of 900° C., the first cycle coulomb efficiency can reach more than 85%; when the calcined temperature is 800° C., the first cycle coulomb efficiency can reach more than 75%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0020] Figure 1 The specific surface area and pore content test results of the hard carbon materials of Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG.

[0021] Figure 2 are microscopic morphology images of the hard carbon materials of Example 1, Comparative Example 1 and Comparative Example 2; wherein (a)-(c) are SEM images of Comparative Example 2, Comparative Example 1 and Example 1, respectively; (d)-(f) are TEM images of Comparative Example 2, Comparative Example 1 and Example 1, respectively; and (g)-(i) are HRTEM images of Comparative Example 2, Comparative Example 1 and Example 1, respectively;

[0022] Figure 3 The charge and discharge curves of the hard carbon materials of Example 1, Comparative Example 1 and Comparative Example 2 at a current density of 30 mA / g;

[0023] Figure 4 Graphs showing the cycle performance of the hard carbon materials of Example 1, Comparative Example 1 and Comparative Example 2 at a current density of 1 A / g;

[0024] Figure 5 The rate performance diagram of the hard carbon materials of Example 1, Comparative Example 1 and Comparative Example 2;

[0025] Figure 6is a charge and discharge curve diagram of the hard carbon material of Example 2 at a current density of 30 mA / g;

[0026] Figure 7 is a charge and discharge curve diagram of the hard carbon material of Example 3 at a current density of 30 mA / g;

[0027] Figure 8 is a charge and discharge curve diagram of the hard carbon material of Example 4 at a current density of 30 mA / g;

[0028] Fig. 9 This is a charge and discharge curve of the hard carbon material of Example 5 at a current density of 30 mA / g. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0030] The present invention will be described in detail below in conjunction with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0031] The present invention aims at the problem that the first-cycle coulomb efficiency of hard carbon materials needs to be improved by carbonizing at a higher calcination temperature, but the higher calcination temperature will cause high energy consumption. A method for preparing a vacuum vapor-filled high-first-efficiency hard carbon material is provided.

[0032] The method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material according to an embodiment of the present invention comprises the following steps: (1) mixing a biomass material and water for a hydrothermal reaction, and after the hydrothermal reaction is completed, performing solid-liquid separation and washing to obtain an intermediate; (2) mixing the intermediate with a hydrochloric acid solution, performing solid-liquid separation, and washing the obtained solid with clean water until the pH is neutral to obtain a purified intermediate; (3) placing the purified intermediate in a first quartz boat, and placing a vapor-filled material in a second quartz boat; the vapor-filled material is an alcohol and / or a hydrocarbon; (4) placing the first quartz boat and the second quartz boat in a Calcination is carried out under vacuum conditions in a tubular furnace to obtain a vacuum vapor-filled high-first-efficiency hard carbon material; in step (4), the tubular furnace has an air inlet and an air outlet, and the second quartz boat and the first quartz boat are sequentially arranged between the air inlet and the air outlet, and nitrogen and / or rare gas are introduced into the tubular furnace through the air inlet to replace the atmosphere in the tubular furnace (in actual operation, replacement is sufficient several times, and there is no need to continuously introduce nitrogen and / or rare gas into the tubular furnace during the calcination process), and the vacuum condition of the tubular furnace during the calcination process is maintained by connecting a vacuum device to the air outlet.

[0033] The method for preparing a vacuum vapor-filled hard carbon material with high first-efficiency of the present invention can effectively reduce the specific surface area of ​​the hard carbon material, increase the graphitized structure of the hard carbon material, and improve the first-cycle coulomb efficiency of the hard carbon material (the gas-phase filling material will be adsorbed into the pores of the carbon material under vacuum conditions, and after carbonization, it can fill the porous structure to reduce the specific surface area of ​​the material, thereby reducing the consumption of electrolyte during the first discharge process); and the method for preparing a vacuum vapor-filled hard carbon material with high first-efficiency of the present invention has a simple process, can achieve the preparation of a hard carbon material with high first-cycle coulomb efficiency at a relatively low temperature, and can effectively reduce the preparation cost of the hard carbon material.

[0034] In a preferred embodiment of the method for preparing a vacuum vapor-filled high-first-effect hard carbon material of the present invention, in step (1), the temperature of the hydrothermal reaction is 100-250°C (for example, 100°C, 120°C, 150°C, 170°C, 200°C, 230°C or 250°C), and the time of the hydrothermal reaction is 1-48h (for example, 1h, 5h, 10h, 20h, 30h, 40h or 48h).

[0035] Preferably, in step (1), the temperature of the hydrothermal reaction is 160-200°C (e.g., 160°C, 170°C, 180°C, 190°C or 200°C), and the time of the hydrothermal reaction is 10-15h (e.g., 10h, 11h, 12h, 13h, 14h or 15h).

[0036] More preferably, the temperature of the hydrothermal reaction is 180° C., and the time of the hydrothermal reaction is 12 h.

[0037] In a preferred embodiment of the method for preparing a vacuum vapor-filled high-first-effect hard carbon material of the present invention, in step (4), the calcination temperature is 800-1600°C (for example, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C or 1600°C), and the calcination time is 1-24h (for example, 1h, 5h, 10h, 15h, 20h or 24h). If the calcination time is too short, incomplete carbonization may result, resulting in poor performance of the prepared hard carbon material; a longer carbonization time may help improve the performance of the hard carbon material.

[0038] Preferably, in step (4), the calcination time is 2-5 h (eg, 2 h, 3 h, 4 h or 5 h).

[0039] In a preferred embodiment of the preparation method of the vacuum vapor-filled high-first-efficiency hard carbon material of the present invention, in step (4), the vacuum degree of the tubular furnace during calcination is P, -0.1MPa≤P<0MPa (for example, -0.1MPa, -0.09MPa, -0.08MPa, -0.07MPa, -0.06MPa, -0.05MPa, -0.04MPa, -0.03MPa, -0.02MPa, -0.01MPa or -0.005MPa, etc.).

[0040] In a preferred embodiment of the method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material of the present invention, the biomass material is charcoal and / or tea oil shell.

[0041] In a preferred embodiment of the method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material of the present invention, the vapor-phase filling material is an alcohol; the alcohol is selected from at least one of methanol, ethanol, ethylene glycol, propanol, butanol, propylene glycol, cyclohexanehexol, benzyl alcohol, pentanol, hexanol and octanol; the vapor-phase filling material is a hydrocarbon; the hydrocarbon is selected from at least one of coal tar, paraffin oil, alkanes, alkenes, alkynes, alicyclic hydrocarbons and aromatic hydrocarbons.

[0042] Preferably, the ratio of the purified intermediate to the gas-phase filling material is 0.8:(1-3) (for example, 0.8:1, 0.8:1.3, 0.8:1.5, 0.8:1.8, 0.8:2, 0.8:2.2, 0.8:2.6 or 0.8:3), the amount of the purified intermediate is measured in g, and the amount of the gas-phase filling material is measured in mL.

[0043] The present invention further proposes a vacuum gas phase filled hard carbon material with high initial efficiency. The vacuum gas phase filled hard carbon material with high initial efficiency in the embodiment of the present invention is prepared by the method described above.

[0044] The present invention further provides a negative electrode. The negative electrode in the embodiment of the present invention contains the vacuum gas phase filled high initial efficiency hard carbon material as described above.

[0045] The present invention also provides a battery. The battery in an embodiment of the present invention contains the vacuum gas phase filled high first efficiency hard carbon material as described above or the negative electrode as described above.

[0046] The vacuum vapor-filled high-initial-efficiency hard carbon material of the present invention and its preparation method and application are described in detail below through specific examples.

[0047] In the following examples, unless otherwise specified, all raw materials used can be purchased commercially; the camellia oleifera shells used in the following examples were produced in Shangrao, Jiangxi Province.

[0048] Example 1

[0049] The method for preparing the vacuum vapor-filled high-initial-efficiency hard carbon material of this embodiment comprises the following steps:

[0050] (1) 2 g of camellia oleifera shells were placed in a reaction kettle, 70 mL of water was added, and the reaction kettle was placed in a 180° C. forced air drying oven for 12 h; after the hydrothermal reaction was completed, the reaction kettle was cooled to room temperature, a solid was obtained by suction filtration, and the obtained solid was washed to obtain an intermediate;

[0051] (2) soaking the intermediate in a hydrochloric acid solution and stirring overnight to remove impurities in the material, separate the solid and liquid, and wash with clean water until the pH is neutral to obtain a purified intermediate;

[0052] (3) 0.8 g of the purified intermediate was placed in a first quartz boat, and 2 mL of glycerol was placed in a second quartz boat;

[0053] (4) Place the first quartz boat and the second quartz boat in a tubular furnace, which has an air inlet and an air outlet. The air inlet, the second quartz boat, the first quartz boat and the air outlet are arranged in sequence, and nitrogen and / or rare gas are introduced into the tubular furnace through the air inlet. The air outlet is connected to a vacuum device (the vacuum device is used to evacuate the tubular furnace to create a vacuum environment); replace the atmosphere in the tubular furnace, and calcine under vacuum conditions (the vacuum degree is -0.095MPa, the calcination temperature is 900°C, and the calcination time is 2h) to obtain the vacuum vapor-filled high-efficiency hard carbon material of this embodiment.

[0054] Example 2

[0055] The method for preparing the vacuum vapor-filled high-initial-efficiency hard carbon material of this embodiment comprises the following steps:

[0056] (1) 2 g of sawdust (oak) was placed in a reactor, 70 mL of water was added, and the reactor was placed in a 180° C. forced air drying oven for 12 h; after the hydrothermal reaction was completed, the mixture was cooled to room temperature, filtered to obtain a solid, and the solid was washed to obtain an intermediate;

[0057] (2) soaking the intermediate in a hydrochloric acid solution and stirring overnight to remove impurities in the material, separate the solid and liquid, and wash with clean water until the pH is neutral to obtain a purified intermediate;

[0058] (3) 0.8 g of the purified intermediate was placed in a first quartz boat, and 2 mL of glycerol was placed in a second quartz boat;

[0059] (4) Place the first quartz boat and the second quartz boat in a tubular furnace, which has an air inlet and an air outlet. The air inlet, the second quartz boat, the first quartz boat and the air outlet are arranged in sequence, and nitrogen and / or rare gas are introduced into the tubular furnace through the air inlet. The air outlet is connected to a vacuum device (the vacuum device is used to evacuate the tubular furnace to create a vacuum environment); replace the atmosphere in the tubular furnace, and calcine under vacuum conditions (the vacuum degree is -0.095MPa, the calcination temperature is 900°C, and the calcination time is 2h) to obtain the vacuum vapor-filled high-efficiency hard carbon material of this embodiment.

[0060] Example 3

[0061] The preparation method of the vacuum vapor-filled high-first-efficiency hard carbon material in this embodiment is different from that in Embodiment 1 only in that the calcination temperature in step (4) is 800° C.; the rest is consistent with Embodiment 1.

[0062] Example 4

[0063] The hard carbon material of this embodiment is different from that of embodiment 1 only in that 1 mL of propylene glycol is used, and the rest is the same as that of embodiment 1.

[0064] Example 5

[0065] The hard carbon material of this embodiment is different from that of embodiment 1 only in that 3 mL of propylene glycol is used, and the rest is the same as that of embodiment 1.

[0066] Comparative Example 1

[0067] The hard carbon material of this comparative example is different from that of Example 1 only in that propylene glycol is omitted, and the rest is the same as that of Example 1.

[0068] Comparative Example 2

[0069] The hard carbon material of this comparative example is different from that of Example 1 only in that the step of evacuating the tube furnace with a vacuum device is omitted (ie, calcination is not carried out under vacuum conditions), and the rest is consistent with Example 1.

[0070] Experimental example

[0071] 1. Specific surface area and pore content test

[0072] The specific surface area and pore content of the hard carbon materials of Example 1 and Comparative Examples 1-2 were tested (nitrogen isothermal adsorption and desorption test, degassing at 300°C for 6h). The test results are as follows: Figure 1 As shown:

[0073] The experimental results show that the specific surface areas of the hard carbon materials in Example 1, Comparative Example 1 and Comparative Example 2 are 96 m 2 / g, 187m 2 / g and 170m2 / g, and the pore content of the hard carbon material of Example 1 is lower than that of Comparative Examples 1 and 2; indicating that the pores in the hard carbon material of Example 1 are successfully filled with the micro-carbon material generated from glycerol vapor.

[0074] 2. Microscopic morphology:

[0075] The hard carbon materials of Example 1, Comparative Example 1 and Comparative Example 2 were respectively subjected to SEM (test equipment: Helios G4CX, Thermo Scientific, Czech Republic), TEM and HRTEM tests (test equipment: HRTEM FEI / Talos F200S):

[0076] Test results such as Figure 2 As shown; wherein, (a)-(c) are SEM images of Comparative Example 2, Comparative Example 1 and Example 1, respectively, (d)-(f) are TEM images of Comparative Example 2, Comparative Example 1 and Example 1, respectively, and (g)-(i) are HRTEM images of Comparative Example 2, Comparative Example 1 and Example 1, respectively.

[0077] Depend on Figure 2 It can be seen that the morphologies of the three hard carbon materials are similar, but the graphitized structure of the hard carbon material in Example 1 is significantly more than that in Comparative Example 1 and Comparative Example 2, and the graphitized structure of Comparative Example 2 is also more than that in Comparative Example 1, indicating that propylene glycol does form more graphitized structures during the vacuum carbonization process.

[0078] 3. The specific charge capacity, first cycle coulomb efficiency, cycle performance and rate performance of the hard carbon materials of the embodiments and comparative examples were tested: hard carbon, conductive carbon and CMC binder were used to prepare battery slurry in a ratio of 8:1:1, coated on copper foil, and cut into 10 mm discs as electrodes after vacuum drying at 80°C for 12 hours. Metal sodium sheet was used as the counter electrode and glass fiber was used as the diaphragm. 1M sodium trifluoromethanesulfonate was dissolved in diethylene glycol dimethyl ether as the electrolyte. The battery was assembled in an argon atmosphere glove box, and then the battery was subjected to constant current charge and discharge tests using the Blue Electric Battery Test System. The current density of the specific capacity and first efficiency tests was 30mA / g, the current density of the cycle stability test was 1A / g, and the current density of the rate test was 30mA / g, 50mA / g, 100mA / g, 500mA / g, 1A / g, and 2A / g.

[0079] Test results:

[0080] (1) The first three charge-discharge curves of the hard carbon materials of Comparative Example 2, Comparative Example 1 and Example 1 are as follows: Figure 3 shown.

[0081] Depend on Figure 3It can be seen that the first-circle coulomb efficiency of the hard carbon material in Example 1 is 85.93%, which is significantly higher than the first-circle coulomb efficiency of the hard carbon materials in Comparative Example 1 and Comparative Example 2 (the first-circle coulomb efficiency of Comparative Example 1 is 60.43%, and the first-circle coulomb efficiency of Comparative Example 2 is 61.22%).

[0082] (2) The cycle performance of the hard carbon materials of Comparative Example 2, Comparative Example 1 and Example 1 at a current density of 1 A / g is shown in the figure below. Figure 4 shown.

[0083] (3) The rate performance diagram of the hard carbon materials of Comparative Example 2, Comparative Example 1 and Example 1 is as follows Figure 5 shown.

[0084] (4) The first three charge-discharge curves of the hard carbon material of Example 2 at a current density of 30 mA / g are as follows: Figure 6 The first-cycle coulombic efficiency of the hard carbon material of Example 2 is 84.9%.

[0085] (5) The first three charge-discharge curves of the hard carbon material of Example 3-5 at a current density of 30 mA / g are as follows: Figure 7-9 The first-cycle coulomb efficiency of the hard carbon material of Example 3 is 76.2%, the first-cycle coulomb efficiency of the hard carbon material of Example 4 is 78.45%, and the first-cycle coulomb efficiency of the hard carbon material of Example 5 is 79.85%.

[0086] The electrochemical test results are shown in Table 1 below:

[0087] Table 1

[0088]

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a vacuum gas phase filled high initial efficiency hard carbon material, characterized in that: The steps include: (1) mixing the biomass material and water to perform a hydrothermal reaction, and after the hydrothermal reaction, performing solid-liquid separation and washing to obtain an intermediate; (2) mixing the intermediate with a hydrochloric acid solution, separating the solid from the liquid, and washing the obtained solid with water until the pH is neutral to obtain a purified intermediate; (3) placing the purified intermediate in a first quartz boat, and placing a gas-phase filling material in a second quartz boat; the gas-phase filling material is alcohol and / or hydrocarbon; (4) placing the first quartz boat and the second quartz boat in a tube furnace and calcining them under vacuum conditions to obtain the vacuum vapor-filled high-primary-efficiency hard carbon material; In step (4), the tubular furnace has an air inlet and an air outlet, and the second quartz boat and the first quartz boat are sequentially arranged between the air inlet and the air outlet. Nitrogen and / or rare gas are introduced into the tubular furnace through the air inlet to replace the atmosphere in the tubular furnace, and the vacuum condition of the tubular furnace is maintained during the calcination process by connecting a vacuum device to the air outlet.

2. The method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material according to claim 1, characterized in that: In step (1), the temperature of the hydrothermal reaction is 100-250° C., and the time of the hydrothermal reaction is 1-48 h.

3. The method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material according to claim 1, characterized in that: In step (4), the calcination temperature is 800-1600° C., and the calcination time is 1-24 hours.

4. The method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material according to claim 1, characterized in that: In step (4), the vacuum degree of the tubular furnace during calcination is P, -0.1MPa≤P<0MPa.

5. The method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material according to claim 1, characterized in that: The biomass material is charcoal and / or tea oil shell.

6. The method for preparing a vacuum vapor-filled high-initial-efficiency hard carbon material according to claim 1, characterized in that: The gas phase filling material is alcohol; the alcohol is selected from at least one of methanol, ethanol, ethylene glycol, propanol, butanol, glycerol, cyclohexanehexol, benzyl alcohol, pentanol, hexanol and octanol; The gas phase filling material is hydrocarbon; the hydrocarbon is selected from at least one of coal tar, paraffin oil, alkane, olefin, alkyne, alicyclic hydrocarbon and aromatic hydrocarbon.

7. A vacuum gas phase filled high initial efficiency hard carbon material, characterized in that: The vacuum gas phase filled high initial efficiency hard carbon material is prepared by the method according to any one of claims 1 to 6.

8. A negative electrode, characterized in that The negative electrode contains the vacuum vapor-filled high-initial efficiency hard carbon material as claimed in claim 7.

9. A battery, characterized in that: The battery contains the vacuum vapor-filled high-initial-efficiency hard carbon material as claimed in claim 7 or the negative electrode as claimed in claim 8.

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