Preparation method of lignite-based petroleum coke composite hard carbon negative electrode material and application of lignite-based petroleum coke composite hard carbon negative electrode material in sodium-ion battery

Abstract

The invention discloses a preparation method of a lignite-based petroleum coke composite hard carbon negative electrode material and application of the lignite-based petroleum coke composite hard carbon negative electrode material in a sodium-ion battery. The preparation method of the hard carbon negative electrode material comprises the following steps: S1, carrying out pre-oxidation treatment on petroleum coke; s2, mixing the pre-oxidized petroleum coke with lignite to form a mixture, and putting the mixture into a tubular furnace for high-temperature pyrolysis; s3, removing ash of a final product through acid leaching treatment; and S4, collecting and drying a final product to obtain the coal-based hard carbon negative electrode material. The lignite-based petroleum coke composite hard carbon negative electrode material prepared by the invention shows excellent electrochemical performance as a negative electrode material of a sodium ion battery, and the preparation method is simple, the raw materials are easy to obtain, the cost is low, the carbon yield is high, and the lignite-based petroleum coke composite hard carbon negative electrode material is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of negative electrode materials for sodium ion batteries, and in particular to a method for preparing a lignite-based petroleum coke composite hard carbon negative electrode material and application thereof in sodium ion batteries. Background Art

[0002] With the growing global energy demand and the gradual depletion of fossil energy, the development of new energy storage and conversion technologies has become an important means to cope with the energy crisis. Sodium-ion batteries are considered to be a potential alternative to lithium-ion batteries due to their abundant sodium resources, low cost, and environmental friendliness, especially in large-scale energy storage systems. However, due to the large radius and heavy mass of sodium ions, there are certain limitations in the selection of battery materials, especially in terms of negative electrode materials. Traditional graphite materials exhibit excellent electrochemical properties as negative electrodes for lithium-ion batteries, but due to the small interlayer spacing of graphite, sodium ions are difficult to embed into them, resulting in sodium-ion batteries being unable to fully utilize graphite as a negative electrode. This limitation has prompted researchers to explore alternative materials suitable for sodium ion embedding, among which hard carbon materials have gradually received widespread attention.

[0003] Hard carbon is a type of amorphous carbon material with a disordered structure and relatively large interlayer spacing, which can provide more sodium ion storage sites, thus showing good sodium storage performance in sodium ion batteries. At present, the mainstream precursor raw materials of hard carbon materials are biomass, resin, asphalt, etc., but due to the problems of unstable raw material supply, high price and complex preparation process, it is difficult to industrialize on a large scale. Coal, as a carbon source with abundant resources, low price and high carbon content, is one of the strong candidates for negative electrode materials of sodium ion batteries. However, coal is usually composed of rich polynuclear aromatic rings, so its derived carbon usually has a highly organized microcrystalline structure and rich surface defects, which affects the capacity of sodium ion batteries. Petroleum coke has a wide source, low price and high carbon yield, and the negative electrode material prepared by it has a large tilted area capacity and a fast kinetic speed. However, petroleum coke-based carbon materials face the disadvantages of graphitization, that is, small interlayer spacing, low specific capacity and initial coulombic efficiency, which is not conducive to their actual performance in sodium ion batteries. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned defects and shortcomings and provide a lignite-based petroleum coke composite hard carbon negative electrode material with a simple preparation method, high carbon yield, low cost and excellent electrochemical properties, thereby promoting its application in sodium ion batteries.

[0005] In order to achieve this object, the technical solution adopted by the present invention is as follows:

[0006] The method for preparing the lignite-based petroleum coke composite hard carbon negative electrode material provided by the present invention is characterized by comprising the following steps:

[0007] S1. crushing the petroleum coke and pre-oxidizing it in an air atmosphere for 10 hours to obtain oxidized petroleum coke;

[0008] S2, mixing lignite and oxidized petroleum coke in a certain mass ratio to form a mixture, and placing the mixture in a tubular furnace for high temperature pyrolysis at 1200° C. for 2 h under an inert atmosphere;

[0009] S3, soaking the black powder obtained in S2 in an acid solution for acid leaching to remove ash from the final product;

[0010] S4. Collect the final product, wash it with deionized water until it is neutral, and dry it to obtain a lignite-based petroleum coke composite hard carbon negative electrode material.

[0011] Furthermore, the pre-oxidation temperature described in S1 is 200-400°C.

[0012] Furthermore, the mass ratio of lignite to oxidized petroleum coke in S2 is 10:(1-10); the inert atmosphere is created by an inert gas, and the inert gas is at least one of argon or nitrogen.

[0013] Furthermore, the acid solution in S3 is at least one of HCl, HNO3, H2SO4 or HClO4, the concentration of the acid solution is 0.1-5M, and the acid leaching time is 6-12h.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The lignite-based petroleum coke composite hard carbon negative electrode material of the present invention uses cheap lignite and petroleum coke as raw materials, which significantly reduces the production cost of hard carbon negative electrode materials. The petroleum coke is mixed with lignite after pre-oxidation treatment, and then subjected to high-temperature calcination and post-treatment processes. The entire process is simple and easy to control.

[0016] 2. The present invention applies the prepared sodium ion battery lignite-based petroleum coke composite hard carbon negative electrode material to the sodium ion battery, and utilizes the synergistic effect of lignite and petroleum coke to exhibit excellent electrochemical performance of the sodium ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the SEM image of the lignite-based petroleum coke composite hard carbon negative electrode material prepared in Example 1

[0018] Figure 2 Electrochemical cycle performance diagram of the battery assembled with the lignite-based petroleum coke composite hard carbon negative electrode material prepared in Example 1 DETAILED DESCRIPTION

[0019] The present invention is further described in detail below by way of examples so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following examples.

[0020] Example 1

[0021] A preparation method and application of a lignite-based petroleum coke composite hard carbon negative electrode material, comprising the following steps

[0022] 1. Synthesize lignite-based petroleum coke composite hard carbon negative electrode material, the specific steps are as follows:

[0023] First, 1.0 g of petroleum coke is crushed and ground into fine powder, placed in an alumina crucible, heated to 350°C at a rate of 5°C / min in a muffle furnace in an air atmosphere for pre-oxidation treatment for 10 hours, and naturally cooled to room temperature to obtain oxidized petroleum coke; then, lignite and oxidized petroleum coke are evenly mixed in a mass ratio of 10:1, placed in a tubular furnace and heated to 1200°C at a rate of 3°C / min in an argon atmosphere for high-temperature pyrolysis for 2 hours; cooled to room temperature, and the black powder obtained in the above steps is immersed in a 3M dilute hydrochloric acid solution with stirring for 6 hours for acid leaching treatment to remove the ash of the final product; finally, the above powder is collected, washed with water to neutrality, and dried to obtain a lignite-based petroleum coke composite hard carbon negative electrode material.

[0024] 2. The prepared lignite-based petroleum coke composite hard carbon negative electrode material was mixed with a conductive agent and a binder in a mass ratio of 8:1:1 to form a uniform slurry, and then the obtained slurry was evenly scraped onto the current collector copper foil with a scraper, and the copper foil was dried at 120°C for 10 hours under vacuum conditions. Finally, the copper foil coated with the sample was pressed into a circular pole piece with a diameter of 1.1 cm using a punching machine and transferred to a glove box for standby use.

[0025] 3. The button cell was assembled in a glove box with an argon atmosphere, with the obtained electrode as the positive electrode, 1M NaPF6 (DME) as the electrolyte, and the metal sodium sheet as the negative electrode. The button cell was subjected to current charge and discharge tests, with a discharge cut-off voltage of 0.01V, a charge cut-off voltage of 2.6V, a test temperature of 30°C, a test current density of 0.1C for the first three cycles, and then a charge and discharge test at a current density of 0.2C (1C = 300mA / g).

[0026] The electrochemical cycling results of the assembled battery are shown in Figure 2 As shown in Table 1, the first cycle discharge capacity of Example 1 is 399.29 mAh / g, and after 40 cycles, it still has a discharge capacity of 224.34 mAh / g.

[0027] Example 2

[0028] A preparation method and application of a lignite-based petroleum coke composite hard carbon negative electrode material, comprising the following steps

[0029] 1. Synthesize lignite-based petroleum coke composite hard carbon negative electrode material, the specific steps are as follows:

[0030] First, 1.0 g of petroleum coke is crushed and finely ground, placed in an alumina crucible, heated to 350°C at a rate of 5°C / min in a muffle furnace in an air atmosphere for pre-oxidation treatment for 10 hours, and naturally cooled to room temperature to obtain oxidized petroleum coke; then, lignite and oxidized petroleum coke are evenly mixed in a mass ratio of 10:4, placed in a tubular furnace and heated to 1200°C at a rate of 3°C / min in an argon atmosphere for high-temperature pyrolysis for 2 hours; cooled to room temperature, and the black powder obtained in the above steps is immersed in a 3M dilute hydrochloric acid solution with stirring for 6 hours for acid leaching treatment to remove the ash of the final product; finally, the above powder is collected, washed with water to neutrality, and dried to obtain a lignite-based petroleum coke composite hard carbon negative electrode material.

[0031] 2. The prepared lignite-based petroleum coke composite hard carbon negative electrode material was mixed with a conductive agent and a binder in a mass ratio of 8:1:1 to form a uniform slurry, and then the obtained slurry was evenly scraped onto the current collector copper foil with a scraper, and the copper foil was dried at 120°C for 10 hours under vacuum conditions. Finally, the copper foil coated with the sample was pressed into a circular pole piece with a diameter of 1.1 cm using a punching machine and transferred to a glove box for standby use.

[0032] 3. The button cell was assembled in a glove box with an argon atmosphere, with the obtained electrode as the positive electrode, 1M NaPF6 (DME) as the electrolyte, and the metal sodium sheet as the negative electrode. The button cell was subjected to current charge and discharge tests, with a discharge cut-off voltage of 0.01V, a charge cut-off voltage of 2.6V, a test temperature of 30°C, a test current density of 0.1C for the first three cycles, and then a charge and discharge test at a current density of 0.2C (1C = 300mA / g).

[0033] The electrochemical cycle results of the assembled battery are shown in Table 1. The first cycle discharge capacity of Example 2 is 372.03 mAh / g. After 40 cycles, it still has a discharge capacity of 217.52 mAh / g.

[0034] Example 3

[0035] A preparation method and application of a lignite-based petroleum coke composite hard carbon negative electrode material, comprising the following steps

[0036] 1. Synthesize lignite-based petroleum coke composite hard carbon negative electrode material, the specific steps are as follows:

[0037] First, 1.0 g of petroleum coke is crushed and finely ground, placed in an alumina crucible, heated to 350°C at a rate of 5°C / min in a muffle furnace in an air atmosphere for pre-oxidation treatment for 10 hours, and naturally cooled to room temperature to obtain oxidized petroleum coke; then, lignite and oxidized petroleum coke are evenly mixed in a mass ratio of 10:7, placed in a tubular furnace and heated to 1200°C at a rate of 3°C / min in an argon atmosphere for high-temperature pyrolysis for 2 hours; cooled to room temperature, and the black powder obtained in the above steps is immersed in a 3M dilute hydrochloric acid solution with stirring for 6 hours for acid leaching treatment to remove the ash of the final product; finally, the above powder is collected, washed with water to neutrality, and dried to obtain a lignite-based petroleum coke composite hard carbon negative electrode material.

[0038] 2. The prepared lignite-based petroleum coke composite hard carbon negative electrode material was mixed with a conductive agent and a binder in a mass ratio of 8:1:1 to form a uniform slurry, and then the obtained slurry was evenly scraped onto the current collector copper foil with a scraper, and the copper foil was dried at 120°C for 10 hours under vacuum conditions. Finally, the copper foil coated with the sample was pressed into a circular pole piece with a diameter of 1.1 cm using a punching machine and transferred to a glove box for standby use.

[0039] 3. The button cell was assembled in a glove box with an argon atmosphere, with the obtained electrode as the positive electrode, 1M NaPF6 (DME) as the electrolyte, and the metal sodium sheet as the negative electrode. The button cell was subjected to current charge and discharge tests, with a discharge cut-off voltage of 0.01V, a charge cut-off voltage of 2.6V, a test temperature of 30°C, and a test current density of 0.1C (1C = 300mA / g) for the first three cycles, followed by a charge and discharge test at a current density of 0.2C.

[0040] The electrochemical cycle results of the assembled battery are shown in Table 1. The first cycle discharge capacity of Example 3 is 427.13 mAh / g. After 40 cycles, it still has a discharge capacity of 204.35 mAh / g.

[0041] Example 4

[0042] A preparation method and application of a lignite-based petroleum coke composite hard carbon negative electrode material, comprising the following steps

[0043] 1. Synthesize lignite-based petroleum coke composite hard carbon negative electrode material, the specific steps are as follows:

[0044] First, 1.0 g of petroleum coke is crushed and finely ground, placed in an alumina crucible, heated to 350°C at a rate of 5°C / min in a muffle furnace in an air atmosphere for pre-oxidation treatment for 10 hours, and naturally cooled to room temperature to obtain oxidized petroleum coke; then, lignite and oxidized petroleum coke are evenly mixed in a mass ratio of 10:10, placed in a tubular furnace and heated to 1200°C at a rate of 3°C / min in an argon atmosphere for high-temperature pyrolysis for 2 hours; cooled to room temperature, and the black powder obtained in the above steps is immersed in a 3M dilute hydrochloric acid solution with stirring for 6 hours for acid leaching treatment to remove the ash of the final product; finally, the above powder is collected, washed with water to neutrality, and dried to obtain a lignite-based petroleum coke composite hard carbon negative electrode material.

[0045] 2. The prepared lignite-based petroleum coke composite hard carbon negative electrode material was mixed with a conductive agent and a binder in a mass ratio of 8:1:1 to form a uniform slurry, and then the obtained slurry was evenly scraped onto the current collector copper foil with a scraper, and the copper foil was dried at 120°C for 10 hours under vacuum conditions. Finally, the copper foil coated with the sample was pressed into a circular pole piece with a diameter of 1.1 cm using a punching machine and transferred to a glove box for standby use.

[0046] 3. The button cell was assembled in a glove box with an argon atmosphere, with the obtained electrode as the positive electrode, 1M NaPF6 (DME) as the electrolyte, and the metal sodium sheet as the negative electrode. The button cell was subjected to current charge and discharge tests, with a discharge cut-off voltage of 0.01V, a charge cut-off voltage of 2.6V, a test temperature of 30°C, and a test current density of 0.1C (1C = 300mA / g) for the first three cycles, followed by a charge and discharge test at a current density of 0.2C.

[0047] The electrochemical cycle results of the assembled battery are shown in Table 1. The first cycle discharge capacity of Example 4 is 327.03 mAh / g. After 40 cycles, it still has a discharge capacity of 181.74 mAh / g.

[0048] Comparative Example 1

[0049] Glucose was heated to 160°C in an argon atmosphere at a heating rate of 3°C / min and kept warm for 3 hours to obtain a pre-carbonized material, and the pre-carbonized material was heated to 1000°C in an argon atmosphere at a heating rate of 3°C / min and kept warm for 3 hours. The pole pieces were prepared, the battery was assembled, and the electrochemical test was performed.

[0050] The electrochemical cycle results of the assembled battery are shown in Table 1. The discharge capacity in the first cycle is 281.48 mAh / g, and the discharge capacity after 40 cycles is 67.96 mAh / g.

[0051] Table 1 Half-cell electrochemical performance test results

[0052]

[0053] The above contents are only preferred embodiments of the present invention and are not intended to limit the invention. Any equivalent replacement, modification and improvement 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 lignite-based petroleum coke composite hard carbon negative electrode material, characterized in that The following steps are involved: S1. crushing the petroleum coke and pre-oxidizing it in an air atmosphere for 10 hours to obtain oxidized petroleum coke; S2, mixing lignite and oxidized petroleum coke in a certain mass ratio to form a mixture, and placing the mixture in a tubular furnace for high temperature pyrolysis at 1200° C. for 2 h under an inert atmosphere; S3, soaking the black powder obtained in S2 in an acid solution for acid leaching to remove ash from the final product; S4. Collect the final product, wash it with deionized water until it is neutral, and dry it to obtain a lignite-based petroleum coke composite hard carbon negative electrode material.

2. The method according to claim 1, characterized in that: The pre-oxidation temperature in S1 is 200-400°C.

3. The method according to claim 1, characterized in that The mass ratio of lignite to oxidized petroleum coke in S2 is 10:(1-10); the inert atmosphere is created by an inert gas, and the inert gas is at least one of argon or nitrogen.

4. The method according to claim 1, characterized in that The acid solution in S3 is at least one of HCl, HNO3, H2SO4 or HClO4, the concentration of the acid solution is 0.1-5M, and the acid leaching time is 6-12h.

5. A lignite-based petroleum coke composite hard carbon negative electrode material, characterized in that: The preparation method is adopted according to claims 1-4.

6. An application of the lignite-based petroleum coke composite hard carbon negative electrode material according to claim 5, characterized in that: The negative electrode material is used as the negative electrode plate of a sodium ion battery.

Images