Preparation method of carbon material and potassium ion battery containing carbon material

Abstract

The invention relates to the technical field of potassium ion batteries, in particular to a high-energy and high-power carbon material, a preparation method thereof and a carbon material containing the high-energy and high-power carbon material, and the specific surface area of the carbon material ranges from 1000 m < 2 > / g to 3000 m < 2 > / g; the internal structure is an ultra-microporous structure, the pore web diameter of the ultra-microporous structure is between 0.5 nm and 1.5 nm, and the pore diameter is between 0.1 nm and 0.5 nm; besides, the particle size distribution of the carbon material is 5-50 microns, and the preparation method of the carbon material comprises the following steps: step 1, carrying out pre-oxidation treatment on a precursor; step 2, mixing the precursor pre-oxidized in the step 1 with hydroxide according to a mass ratio of the hydroxide to the pre-treated precursor of 1: 1-2: 1, then performing activation treatment at high temperature, and performing acid pickling and filtering after activation to obtain a porous carbon material; and step 3, performing chemical vapor deposition (CVD) on the porous carbon material in the step 2, and reducing the pore size of the porous carbon to obtain the amorphous carbon material with an ultra-microporous structure inside.

Description

Technical Field

[0001] The present invention relates to the technical field of potassium ion batteries, and particularly to a high-energy and high-power carbon material, a preparation method thereof, and a potassium ion battery comprising the carbon material. Background Art

[0002] With the global emphasis on energy transition and carbon emission reduction, lithium ion batteries, as an important energy storage technology, have been widely used in various fields. However, the shortage of lithium resources and the continuous increase in their prices have become important factors restricting their development. In contrast, potassium ion batteries have gradually become an alternative energy storage technology attracting much attention due to the abundance of potassium resources and low costs. Potassium ion batteries have a similar working principle to lithium ion batteries and have potential advantages. Especially in large-scale energy storage applications, potassium ion batteries are expected to become a powerful supplement to lithium ion batteries.

[0003] Amorphous carbon materials have become the most commercially promising choice for the anode materials of potassium ion batteries due to their low cost, relatively low working potential, and excellent cycle stability. However, the main challenges faced by these materials currently are the low reversible specific capacity and unsatisfactory rate performance, which seriously affect the application and development of high-energy and high-power potassium ion batteries. To solve these problems, researchers have deeply explored the potassium storage mechanism of amorphous carbon and found that its plateau capacity mainly comes from the filling of potassium ions in the carbon pores. Therefore, the role of the pore structure in battery performance is crucial. By optimizing and regulating the pore structure, it is expected to effectively improve the energy density and power density of potassium ion batteries, thus promoting the development of more efficient energy storage systems.

[0004] Based on this, the present invention proposes an innovative pore-forming method. Petroleum coke is selected as the precursor, and after pre-oxidation and activation treatments, the pore mouth size is adjusted by chemical vapor deposition to obtain a super-microporous carbon material with a high specific surface area and a small pore belly size. Its ultra-high specific surface area helps to provide abundant potassium ion storage sites, while the extremely small pore belly size is conducive to the aggregation reaction of potassium ions in the pores, thereby accelerating the reaction process. Therefore, when this material is applied to the anode of potassium ion batteries, it can maintain a specific capacity of more than 390 mAh / g at a rate of 0.1C and a specific capacity of more than 300 mAh / g at a rate of 4C. Summary of the Invention

[0005] The purpose of the present invention is to: aiming at the technical bottlenecks of low reversible specific capacity and poor rate performance of the carbon anode materials of potassium ion batteries, provide a preparation method of a high-energy and high-power carbon material to promote the commercialization process of high specific energy and high-power potassium ion batteries.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A preparation method of a carbon material, the specific surface area of the carbon material ranges from 1000 to 3000 m 2 / g; its internal structure is a super microporous structure, and the pore belly diameter of the super microporous structure is between 0.5 nm and 1.5 nm, and the pore mouth diameter ranges from 0.1 nm to 0.5 nm; in addition, the particle size of the carbon material is distributed between 5 and 50 microns. Through its unique pore structure and appropriate particle size, the carbon material can exhibit excellent performance in high-power applications.

[0008] The preparation method includes the following steps:

[0009] Step 1, pre-oxidize the precursor.

[0010] Step 2, mix the pre-oxidized precursor in Step 1 with a hydroxide, and the mass ratio of the hydroxide to the pre-treated precursor is 1:1 to 2:1. Then, perform an activation treatment at a high temperature. During the activation process, the pre-oxidized precursor has a large number of grafted oxygen-containing functional groups, so the activation sites for reacting with the base increase. After activation, perform pickling and filtration to obtain a porous carbon material.

[0011] Step 3, perform chemical vapor deposition (CVD) on the porous carbon material in Step 2 to reduce the pore mouth size of the porous carbon and obtain an amorphous carbon material with a super microporous structure inside.

[0012] As an improvement to the preparation method of the carbon material of the present invention, the precursor in Step 1 is a petroleum coke raw material, and the pre-oxidation treatment is to treat the petroleum coke raw material with air, nitric acid or hydrogen peroxide.

[0013] As an improvement to the preparation method of the carbon material of the present invention, the sulfur content of the petroleum coke raw material is 2.8 - 5 wt%. Different sulfur contents will affect the pre-oxidation effect. Sulfur can provide active sites for oxidation reactions, promote the introduction of oxygen-containing functional groups in the carbon material, and further improve the activation effect.

[0014] As an improvement to the preparation method of the carbon material of the present invention, in Step 1, the temperature for air pre-oxidation of the petroleum coke raw material is 200 - 400 °C, the concentration of nitric acid pre-oxidation is 0.5 - 2 M, the concentration of hydrogen peroxide pre-oxidation is 10% - 30%, the mixing and stirring treatment time of the nitric acid and the petroleum coke raw material is 8 - 12 h, and the mixing and stirring treatment time of the hydrogen peroxide solution and the petroleum coke raw material is 8 - 12 h.

[0015] As an improvement to the preparation method of the carbon material of the present invention, the hydroxide in Step 2 is potassium hydroxide or sodium hydroxide, and the mass ratio of the hydroxide to the precursor pre-treated in Step 1 is 2:1 to 3:1.

[0016] As an improvement to the preparation method of the carbon material of the present invention, the activation treatment temperature is 800 - 900 °C, and the activation treatment time is 60 - 180 min. The mass ratio of the hydroxide to the pretreated precursor is 2:1 - 3:1. It is not suitable to be too low or too high. If the alkali-carbon ratio is too low, the specific surface area will be reduced, resulting in an underdeveloped pore structure, which is not conducive to rich potassium storage sites. If the alkali-carbon ratio is too high, over-activation will occur, the micropores will collapse, and the pore size will increase, which is not conducive to high-power potassium storage.

[0017] As an improvement to the preparation method of the carbon material of the present invention, in step 3, the carbon source gas selected for the chemical vapor deposition is methane, ethane, toluene or xylene, the protective gas is nitrogen or argon, the temperature of the chemical vapor deposition is 700 - 1100 °C, and the deposition time is 60 - 1440 min; the gas velocity of the carbon source gas is 10 ml / min - 6000 ml / min, and the gas velocity of the carrier gas is 100 ml / min - 5000 ml / min.

[0018] As an improvement to the preparation method of the carbon material of the present invention, in step 3, the mass ratio of the porous carbon material to the carbon source gas is (8 - 12):1.

[0019] The present invention also provides a potassium ion battery, which at least includes a positive electrode, a negative electrode, and an electrolyte, and is characterized in that the negative electrode active material therein is the high-energy and high-power carbon material prepared by the present invention.

[0020] As an improvement to the potassium ion battery of the present invention, the capacity retention rate of the battery at a 4C rate is greater than 70%.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. The present invention adopts a high specific surface area and high-power carbon material and its preparation method. There is an extremely rich ultra-microporous structure inside the carbon material, that is, it has both an ultra-high specific surface area (1000 - 3000 m 2 / g) and an ultra-small pore belly size (0.5 - 1.5 nm). The ultra-high specific surface area is conducive to providing rich potassium storage sites, while the ultra-small pore belly size is conducive to promoting the clustering reaction of potassium ions in the pores and improving the reaction rate. When the above carbon negative electrode material is used as the negative electrode of a potassium ion battery, the capacity retention rate is above 70% at a 4C rate. Thus, a potassium ion secondary battery using the hard carbon negative electrode material of the present invention has both high energy density and power density at the same time;

[0023] 2. The present invention uses petroleum raw materials and biomass materials as precursors, which are widely sourced and low in cost. In addition, the preparation process is simple. Therefore, it has good cost advantages;

[0024] 3. Through the three-step collaborative innovation of "pre-oxidation - alkali activation - CVD", the present invention realizes the effect of improving the specific surface area of carbon materials (>1800 m 2 / g) through oxidation activation, and realizes the precise regulation of the pore mouth size (0.1 - 0.5 nm) through chemical vapor deposition, thereby obtaining appropriate pore mouth size and pore belly size, and further obtaining high-energy and high-power carbon materials with good performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the SEM image of the carbon negative electrode material of the potassium ion battery in Example 1 of the present invention.

[0026] Figure 2 It is the nitrogen adsorption and desorption curve of the carbon negative electrode material of the potassium ion battery in Example 1 of the present invention.

[0027] Figure 3 It is the pore size distribution curve of the carbon negative electrode material of the potassium ion battery in Example 1 of the present invention.

[0028] Figure 4 It is the charge and discharge curve of the potassium ion battery at different current densities in Example 1 of the present invention.

[0029] Figure 5 It is the rate performance graph of the potassium ion battery in Example 1 of the present invention.

[0030] Figure 6 It is the pore size distribution curve of the carbon negative electrode material of the potassium ion battery in Comparative Example 1 of the present invention.

[0031] Figure 7 It is the rate performance graph of the potassium ion battery in Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings.

[0033] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in detail with reference to the accompanying drawings.

[0035] In the following embodiments, the pore mouth diameter of the high-energy and high-power carbon material is less than 0.5 nm.

[0036] Example 1

[0037] This embodiment provides a high-energy and high-power carbon material. The specific surface area of the carbon material is 2327.8 m 2 / g, the average pore belly diameter is 1.34 nm, the pore mouth diameter range is from 0.1 nm to 0.5 nm, and the particle size D50 of the carbon anode material is 10 μm.

[0038] The preparation method of the carbon anode material includes the following steps:

[0039] Step 1: Use petroleum coke raw material (sulfur content is 4 wt%) as the precursor, crush it into flaky particles, and stir at room temperature in 30% concentration hydrogen peroxide solution for 8 h;

[0040] Step 2: Dry-mix the pre-oxidized petroleum coke carbon with potassium hydroxide, the mass ratio of alkali to carbon is 2:1, activate it at 800 °C for 180 min, and then perform pickling and water washing;

[0041] Step 3: Take 100 mg of petroleum coke-based porous carbon obtained in Step 2, use methane as the carbon source gas and nitrogen as the protective gas, perform chemical vapor deposition at 900 °C for 180 min, where the methane flow rate is 10 ml / min and the nitrogen flow rate is 100 ml / min, and consume 850 mg of methane to obtain the above-mentioned high-energy and high-power carbon anode material.

[0042] The SEM of the high-energy and high-power carbon material provided by Example 1 is as Figure 1 shown. The results show that the prepared high-energy and high-power carbon anode material shows a typical blocky morphology, and its particle size is 5 - 10 μm.

[0043] The nitrogen adsorption and desorption curve of the high-energy and high-power carbon material provided by Example 1 is as Figure 2 shown. It can be seen from the figure that through the synergistic optimization of the pre-oxidation treatment and the activation process, a hierarchical porous carbon material can be constructed. Its nitrogen adsorption and desorption curve shows a type I isotherm, with the characteristic of high adsorption capacity, directly reflecting the superiority of the pore structure.

[0044] The pore size distribution curve of the high-energy and high-power carbon material provided by Example 1 is as Figure 3 shown. It can be seen from the figure that the pore belly size is mainly concentrated at 0.6 nm and 1.9 nm.

[0045] Assemble a potassium-ion battery using the high-energy and high-power carbon material provided by Example 1. The charge and discharge curves of the potassium-ion battery at different current densities are as Figure 4As shown, the active material of the negative electrode is the above-mentioned high-energy and high-power carbon negative electrode material, the active material of the positive electrode is a potassium sheet, and the electrolyte is 1 M KPF6 dissolved in dimethyl carbonate (DMC): ethylene carbonate (EC) = 1:1. The capacities of the battery at 0.1 C and 4 C were tested and the capacity retention rate was calculated. The results are shown in Table 1.

[0046] It can be seen from Figure 4 that: This curve reflects the excellent electrochemical properties of the material, indicating that the microporous structure of the material provides abundant active sites for potassium storage.

[0047] Figure 5 This is the rate performance graph of the potassium-ion battery in Example 1 of the present invention. It can be seen from this graph that: the capacity reaches 390 mAh / g at a rate of 0.1 C, and the capacity remains 300 mAh / g at a rate of 4 C, and its capacity retention rate exceeds 75%. This rate performance graph shows the advantages of the porous carbon material negative electrode in high-energy density scenarios.

[0048] Example 2

[0049] This example provides a high-energy and high-power carbon material. The specific surface area of the carbon negative electrode material is 2216.8 m 2 / g, the average pore belly diameter is 1.31 nm, the pore mouth diameter range is 0.1 nm to 0.5 nm, and the particle size D50 of the carbon negative electrode material is 8 μm.

[0050] The preparation method of this carbon negative electrode material includes the following steps:

[0051] Step 1: Use petroleum coke (sulfur content is 3 wt%) as the precursor, crush it into flaky particles, and stir at room temperature in a 1 M nitric acid solution for 8 h;

[0052] Step 2: Dry-mix the pre-oxidized petroleum coke carbon with potassium hydroxide, the mass ratio of alkali to carbon is 3:1, activate at 850 °C for 150 min, and then perform pickling and water washing;

[0053] Step 3: Take 100 mg of the petroleum coke-based porous carbon obtained in Step 2, use methane as the carbon source gas, use nitrogen as the protective gas, where the methane flow rate is 20 ml / min and the nitrogen flow rate is 200 ml / min, and perform chemical vapor deposition at 900 °C for 80 min, consuming 1100 mg of methane, to obtain the above-mentioned high-energy and high-power carbon negative electrode material.

[0054] Use the high-energy and high-power carbon material provided in Example 2 to assemble a potassium-ion battery, where the active material of the negative electrode is the above-mentioned high-energy and high-power carbon negative electrode material, the active material of the positive electrode is a potassium sheet, and the electrolyte is 1 M KPF6 dissolved in dimethyl carbonate (DMC): ethylene carbonate (EC) = 1:1. Test the capacity of the battery at 0.1 C and 4 C and calculate the capacity retention rate. The results are shown in Table 1.

[0055] Example 3

[0056] This example provides a high-energy and high-power carbon material. The specific surface area of the carbon negative electrode material is 1860.3 m 2 / g, the average pore belly diameter is 1.35 nm, the pore mouth diameter range is 0.1 nm to 0.5 nm, and the particle size D50 of the carbon negative electrode material is 8 μm.

[0057] The preparation method of the carbon negative electrode material includes the following steps:

[0058] Step 1, Use petroleum coke (sulfur content is 3.5 wt%) as the precursor, crush it into flaky particles, and heat it at 300 °C in an air atmosphere for 3 h at 300 °C;

[0059] Step 2, Dry-mix the pre-oxidized petroleum coke carbon with potassium hydroxide, the mass ratio of alkali to carbon is 2.5:1, activate it at 800 °C for 180 min, and then perform pickling and water washing;

[0060] Step 3, Take 100 mg of the petroleum coke-based porous carbon obtained in Step 2, use methane as the carbon source gas and nitrogen as the protective gas, where the methane flow rate is 20 ml / min and the nitrogen flow rate is 200 ml / min, and perform chemical vapor deposition at 900 °C for 80 min, consuming 1100 mg of methane, to obtain the above-mentioned high-energy and high-power carbon negative electrode material.

[0061] Use the high-energy and high-power carbon material provided in Example 3 to assemble a potassium-ion battery, where the active material of the negative electrode is the above-mentioned high-energy and high-power carbon negative electrode material, the active material of the positive electrode is a potassium sheet, and the electrolyte is 1 M KPF6 dissolved in dimethyl carbonate (DMC): ethylene carbonate (EC) = 1:1. Test the capacity of the battery at 0.1 C and 4 C and calculate the capacity retention rate. The results are shown in Table 1.

[0062] Example 4

[0063] This example provides a high-energy and high-power carbon material. The specific surface area of the carbon negative electrode material is 2520 m 2 / g, the average pore belly diameter is 1.25 nm, the pore mouth diameter range is 0.1 nm to 0.5 nm, and the particle size D50 of the carbon negative electrode material is 10 μm.

[0064] The preparation method of the carbon negative electrode material includes the following steps:

[0065] Step 1: Use petroleum coke (sulfur content is 3.2 wt%) as the precursor, crush it into flaky particles, and stir it at room temperature in a nitric acid solution with a concentration of 1.5 M for 10 h;

[0066] Step 2: Dry-mix the pre-oxidized petroleum coke carbon with sodium hydroxide, with the mass ratio of alkali to carbon being 2.4:1, activate it at 880 °C for 120 min, and then perform pickling and water washing;

[0067] Step 3: Take 100 mg of the petroleum coke-based porous carbon obtained in Step 2, use ethane as the carbon source gas and argon as the protective gas, with the flow rate of ethane being 30 ml / min and the flow rate of argon being 300 ml / min, perform chemical vapor deposition at 1000 °C for 100 min, consume 3000 mg of ethane, and obtain the above-mentioned high-energy and high-power carbon negative electrode material.

[0068] Assemble a potassium battery using a high-energy and high-power carbon material provided in Example 4, where the active material of the negative electrode is the above-mentioned high-energy and high-power carbon negative electrode material, the active material of the positive electrode is a potassium sheet, and the electrolyte is 1 M KPF6 dissolved in dimethyl carbonate (DMC): ethylene carbonate (EC) = 1:1. Test the capacity of the battery at 0.1 C and 4 C and calculate the capacity retention rate. The results are shown in Table 1.

[0069] Example 5

[0070] This example provides a high-energy and high-power carbon material. The specific surface area of the carbon material is 1867 m2 / g, the average pore belly diameter is 1.05 nm, the pore mouth diameter range is from 0.1 nm to 0.5 nm, and the particle size D50 of the carbon negative electrode material is 15 μm.

[0071] The preparation method of the carbon negative electrode material includes the following steps:

[0072] Step 1: Use petroleum coke raw material (sulfur content is 4.2 wt%) as the precursor, crush it into flaky particles, and stir it at room temperature in a hydrogen peroxide solution with a concentration of 20% for 10 h;

[0073] Step 2: Dry-mix the pre-oxidized petroleum coke carbon with potassium hydroxide, with the mass ratio of alkali to carbon being 2.2:1, and activate it at 840 °C for 120 min, and then perform pickling and water washing;

[0074] Step 3: Take 100 mg of the petroleum coke-based porous carbon obtained in Step 2, use toluene as the carbon source gas and nitrogen as the protective gas, and perform chemical vapor deposition at 900 °C for 180 min, where the toluene flow rate is 10 ml / min, the nitrogen flow rate is 100 ml / min, and 850 mg of toluene is consumed to obtain the above-mentioned high-energy and high-power carbon anode material.

[0075] Assemble a potassium ion battery using the high-energy and high-power carbon material provided in Example 5, where the active material of the negative electrode is the above-mentioned high-energy and high-power carbon anode material, the active material of the positive electrode is a potassium sheet, and the electrolyte is 1 M KPF6 dissolved in dimethyl carbonate (DMC): ethylene carbonate (EC) = 1:1. Test the capacity of the battery at 0.1 C and 4 C and calculate the capacity retention rate. The results are shown in Table 1.

[0076] Example 6

[0077] This example provides a high-energy and high-power carbon material. The specific surface area of the carbon anode material is 2523.3 m 2 / g, the average pore belly diameter is 1.45 nm, the pore mouth diameter range is from 0.1 nm to 0.5 nm, and the particle size D50 of the carbon anode material is 9 μm.

[0078] The preparation method of the carbon anode material includes the following steps:

[0079] Step 1: Use petroleum coke (sulfur content is 3.8 wt%) as the precursor, crush it into flaky particles, and heat it in an air atmosphere at 250 °C for 4 h;

[0080] Step 2: Dry-mix the pre-oxidized petroleum coke carbon with sodium hydroxide, with the mass ratio of alkali to carbon being 2.5:1, activate it at 840 °C for 140 min, and then perform pickling and water washing;

[0081] Step 3: Take 100 mg of the petroleum coke-based porous carbon obtained in Step 2, use methane as the carbon source gas and nitrogen as the protective gas, where the methane flow rate is 40 ml / min and the nitrogen flow rate is 500 ml / min, and perform chemical vapor deposition at 800 °C for 100 min, consuming 1100 mg of methane to obtain the above-mentioned high-energy and high-power carbon anode material.

[0082] Assemble a potassium ion battery using a high-energy and high-power carbon material provided in Example 6, where the active material of the negative electrode is the above-mentioned high-energy and high-power carbon anode material, the active material of the positive electrode is a potassium sheet, and the electrolyte is 1 M KPF6 dissolved in dimethyl carbonate (DMC): ethylene carbonate (EC) = 1:1. Test the capacity of the battery at 0.1 C and 4 C and calculate the capacity retention rate. The results are shown in Table 1.

[0083] Comparative Example 1

[0084] Differing from Example 1: In the method for preparing the carbon negative electrode, petroleum coke is not pre-oxidized, but directly activated with potassium hydroxide. The mass ratio of alkali to carbon is 2:1, and the rest is the same as in Example 1, which will not be elaborated here. Figure 6 This is the pore size distribution curve of the carbon negative electrode material for the potassium ion battery in Comparative Example 1. Figure 7 This is the rate performance graph of the potassium ion battery in Comparative Example 1. Figure 6 and Figure 7 It can be seen that omitting the pre-oxidation step results in a single pore structure after the activation of petroleum coke, leading to a decline in electrochemical performance at high rates.

[0085] The carbon material prepared in this comparative example has a specific surface area of 1785.4 m 2 / g and an average pore diameter of 1.85 nm.

[0086] Table 1: Performance of the carbon materials obtained in Examples 1-3 and Comparative Example 1

[0087]

[0088] As can be seen from Table 1, an increase in the specific surface area of the carbon material is beneficial to the improvement of the mass specific capacity at a low rate of 0.1C. However, when the pore diameter of the carbon material increases (greater than 1.4 nm), the mass specific capacity of the carbon material rapidly decreases at a high rate of 4C. By using the improved method of the present invention, the specific surface area of the carbon material can be accurately controlled within 1000 - 4000 m 2 / g, and the pore diameter within 0.5 - 1.5 nm. The ultra-high specific surface area is beneficial to providing abundant potassium storage sites, and the ultra-small pore diameter is beneficial to promoting the clustering reaction of potassium ions in the pores and improving the reaction rate. Thus, the potassium ion secondary battery using the hard carbon negative electrode material of the present invention has both high energy density and power density.

[0089] According to the disclosure and teachings of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A preparation method of a carbon material, characterized in that, The specific surface area of the carbon material ranges from 1000 to 3000 m 2 / g; its internal structure is a super microporous structure, and the pore belly diameter of the super microporous structure is between 0.5 nm and 1.5 nm, and the pore mouth diameter ranges from 0.1 nm to 0.5 nm; in addition, the particle size of the carbon material is distributed between 5 and 50 microns, and its preparation method includes the following steps: Step 1, pre-oxidize the precursor; Step 2, mix the pre-oxidized precursor obtained in Step 1 with a hydroxide, the mass ratio of the hydroxide to the pre-treated precursor is 1:1 to 2:1, then perform an activation treatment at a high temperature, and after activation, perform pickling and filtration to obtain a porous carbon material; Step 3, perform chemical vapor deposition (CVD) on the porous carbon material obtained in Step 2 to reduce the pore mouth size of the porous carbon and obtain an amorphous carbon material with a super-microporous structure inside; 2. The preparation method of the carbon material according to claim 1, wherein: The precursor in Step 1 is a petroleum coke raw material, and the pre-oxidation treatment is to treat the petroleum coke raw material with air, nitric acid or hydrogen peroxide; 3. The preparation method of the carbon material according to claim 2, wherein: The sulfur content of the petroleum coke raw material is 2.8 - 5 wt%; 4. The preparation method of the carbon material according to claim 2, wherein: In Step 1, the temperature for air pre-oxidation of the petroleum coke raw material is 200 - 400 °C; the concentration of nitric acid for pre-oxidation is 0.5 - 2 M, and the mixing and stirring treatment time of nitric acid and the petroleum coke raw material is 8 - 12 h; the concentration of hydrogen peroxide for pre-oxidation is 10% - 30%, and the mixing and stirring treatment time of the hydrogen peroxide solution and the petroleum coke raw material is 8 - 12 h; 5. The preparation method of the carbon material according to claim 1, characterized in that: The hydroxide in Step 2 is potassium hydroxide or sodium hydroxide, and the mass ratio of the hydroxide to the precursor pre-treated in Step 1 is 2:1 to 3:1; 6. The preparation method of the carbon material according to claim 1, wherein: The temperature of the activation treatment is 800 - 900 °C, and the time of the activation treatment is 60 - 180 min; 7. The preparation method of the carbon material according to claim 1, characterized in that: In Step 3, the carbon source gas selected for the chemical vapor deposition is methane, ethane, toluene or xylene, the protective gas is nitrogen or argon, the temperature of the chemical vapor deposition is 700 - 1100 °C, the deposition time is 60 - 1440 min; the gas velocity of the carbon source gas is 10 ml / min - 6000 ml / min, and the gas velocity of the carrier gas is 100 ml / min - 5000 ml / min; 8. The preparation method of the carbon material according to claim 7, characterized in that: In Step 3, the mass ratio of the porous carbon material to the carbon source gas is (8 - 12):1; 9. A potassium ion battery, comprising at least a positive electrode, a negative electrode, and an electrolyte, characterized in that, The negative electrode active material therein is the carbon material prepared according to any one of Claims 1 - 8; 10. The potassium ion battery according to claim 9, wherein: The capacity retention rate of the battery at a 4C rate is greater than 70%.

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