Hard carbon composite material and preparation method and application thereof
Graphene-modified hard carbon composites were prepared by graphene oxide dispersion and microwave treatment, which solved the problems of insufficient capacity and short life of commercial hard carbon materials and realized the application of efficient and low-cost lithium-ion batteries.
Patent Information
- Application Number
- CN202510597577.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-09
- Publication Date
- 2025-09-19
AI Technical Summary
Commercial hard carbon materials have problems such as insufficient capacity, short cycle life, and low initial Coulombic efficiency, making them difficult to produce on a large scale and costly.
Graphene oxide is used as a dispersant. By dispersing hard carbon in water and performing in-situ reduction and modification under microwave conditions, a graphene-modified hard carbon composite material is formed. The conductivity and electrochemical activity of the hard carbon are improved by the reduction and coating modification of graphene oxide.
The prepared hard carbon composite material has high specific capacity and long cycle life. When used in lithium-ion batteries, the specific capacity is as high as 179-235 mAh/g, the cycle life is as long as 200 cycles, and the capacity is retained at 98-100%. It is easy to operate, low cost, and suitable for large-scale production.
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Figure CN120674455A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to a hard carbon composite material and a preparation method and application thereof. Background Art
[0002] With the development and application of unmanned equipment in various scenarios, improving their endurance has become crucial for achieving long-term operation. For example, uninhabited areas such as high mountains or primeval forests often require drone exploration, which places a significant strain on their endurance. Therefore, developing electrochemical energy storage devices with high energy storage capacity has become crucial.
[0003] Hard carbon materials have the advantages of a wide range of raw material sources, high stability and adaptability. They have been commercialized and widely used in the fields of power batteries and energy storage, especially in lithium-ion batteries. The development of the next generation of high-energy, long-life lithium-ion battery technology using hard carbon as the negative electrode has become the key to whether drones can achieve long-term flight and high payload. However, hard carbon has problems such as low initial coulombic efficiency, low actual capacity, insufficient fast charging capability, and poor cycle life. Although there are many methods for developing high-performance hard carbon materials, many methods have problems such as difficulty in scalability and high cost. Although the cost of commercial hard carbon has been greatly reduced, most of them still have problems such as low capacity, short cycle life, and low initial efficiency. Therefore, how to solve these problems of commercial hard carbon has become the key to the widespread application of commercial hard carbon. Summary of the Invention
[0004] In view of the above shortcomings, the present invention provides a method for preparing a hard carbon composite material to solve the problems of insufficient capacity and short cycle life of commercial hard carbon materials. The specific technical solution is as follows:
[0005] A method for preparing a hard carbon composite material comprises the following steps:
[0006] (1) Dispersion of graphene oxide: Graphene oxide was added to deionized water and stirred to obtain a graphene oxide dispersion.
[0007] (2) Dispersion of hard carbon: taking hard carbon, adding it to the graphene oxide dispersion obtained in step (1), stirring evenly, and preparing a hard carbon / graphene oxide dispersion;
[0008] (3) Drying the hard carbon / graphene oxide dispersion: drying and crushing the hard carbon / graphene oxide dispersion to obtain a hard carbon / graphene oxide composite powder;
[0009] (4) Microwave treatment of hard carbon / graphene oxide composite: Put the hard carbon / graphene oxide composite powder into a microwave oven and microwave treat it for a period of time to obtain a hard carbon composite material.
[0010] Preferably, in the above-mentioned method for preparing the hard carbon composite material, the flake diameter of the graphene oxide is 5 to 10 μm, and the graphene oxide is a commercial material.
[0011] Preferably, in the above-mentioned method for preparing the hard carbon composite material, in the step (1), the stirring rate is 800 to 1000 rpm, and the stirring time is 60 to 90 min.
[0012] Preferably, in the above-mentioned method for preparing the hard carbon composite material, the concentration of graphene oxide in the graphene oxide dispersion is 8 to 12 g / L.
[0013] Preferably, in the above-mentioned method for preparing the hard carbon composite material, in step (2), the mass ratio of hard carbon to graphene oxide is 8:1 to 13:1, and the hard carbon is a commercial material.
[0014] Preferably, in the above-mentioned method for preparing the hard carbon composite material, in the step (2), the stirring rate is 1200-1400 rpm, and the stirring time is 60-90 min.
[0015] Preferably, in the above-mentioned method for preparing the hard carbon composite material, in the step (3), the drying temperature is 50 to 80° C., and the drying time is 24 to 30 hours.
[0016] Preferably, in the above-mentioned method for preparing the hard carbon composite material, in the step (4), microwave treatment is carried out in an air atmosphere, the microwave power is 600-800 W, and the microwave time is 10-20 s.
[0017] Preferably, in the above-mentioned method for preparing the hard carbon composite material, the pulverization time is 3 to 5 minutes.
[0018] A hard carbon composite material is prepared by the above-mentioned preparation method.
[0019] Application of the above-mentioned hard carbon composite material in the preparation of battery negative electrode materials.
[0020] This invention proposes, for the first time, the use of graphene oxide as a dispersant to fully disperse a hydrophobic hard carbon material in water. The graphene oxide is then used to fully modify the hard carbon in water, and then in situ reduction of the graphene oxide and tight coating of the hard carbon are achieved under microwave conditions, significantly enhancing the conductivity and electrochemical activity of the hard carbon. Specifically, by using graphene oxide flakes of 5-10 μm in diameter to form a highly dispersed, viscous aqueous dispersion of graphene oxide at a high concentration, the viscosity of the dispersion is controlled. This viscous dispersion then fully disperses the hydrophobic hard carbon in water, ensuring that the hard carbon will not settle for more than a year after dispersion. The interaction between the graphene oxide and the hard carbon is simultaneously utilized to achieve in-situ coating of the hard carbon with the graphene oxide. Furthermore, the hard carbon's strong microwave absorption and heat conversion ability is exploited to achieve uniform and rapid temperature increases, allowing the thermal decomposition and reduction of the graphene oxide on its surface to occur in a very short time, yielding an in-situ graphene-modified hard carbon composite material. Furthermore, the carbon dioxide, water vapor, and carbon monoxide gases produced by the decomposition of graphene oxide protect the hard carbon and the resulting graphene from further oxidation by air at high temperatures, thereby achieving surface modification of the hard carbon in air. Compared to other methods, this method is entirely performed in an air environment, requiring no protective gas, and offers shorter processing times and higher efficiency. Furthermore, the equipment is conventional, the process is simple, and it can be scalable for widespread application. Furthermore, the raw materials and reagents used throughout the process are commercially available, widely available, and low-cost.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] 1. The hard carbon composite material produced by the preparation method of the present invention exhibits high specific capacity and long cycle life, resolving the issues of low capacity and short cycle life of commercial hard carbon materials. The product exhibits high activity and, when used in lithium-ion batteries, achieves a high specific capacity of 179-235 mAh / g and a long cycle life, with 98-100% capacity retention after 200 cycles.
[0023] 2. The present invention uses graphene oxide as a dispersant to achieve full dispersion and coating of hydrophobic hard carbon materials in water, and uses graphene oxide to fully modify the hard carbon in water. Microwave treatment is then used to in situ reduce the graphene oxide and tightly coat the hard carbon, significantly improving the conductivity and electrochemical activity of the hard carbon material.
[0024] 3. This method uses a short-term microwave treatment in air to thermally decompose and reduce graphene oxide, achieving surface modification of hard carbon. Compared to other methods, this method is entirely performed in air, requiring no protective gas, and offers shorter processing times and higher efficiency. Furthermore, conventional equipment and a simple process facilitate scalable production and widespread application. Furthermore, the raw materials and reagents used throughout the process are commercially available, widely available, and inexpensive. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.
[0026] Figure 1 is the SEM image of the commercial hard carbon material used;
[0027] Figure 2 This is a SEM image of the hard carbon composite material prepared in Example 1;
[0028] Figure 3 This is the XRD pattern of the hard carbon composite material prepared in Example 1;
[0029] Figure 4 This is the XPS graph of the hard carbon composite material prepared in Example 1;
[0030] Figure 5 is a dispersion diagram of the hard carbon / graphene oxide dispersion of Comparative Example 1;
[0031] Figure 6 is a dispersion diagram of the hard carbon / graphene oxide dispersion of Example 1;
[0032] Figure 7 This is a constant current charge and discharge (GCD) diagram of the hard carbon composite material prepared in Comparative Example 2;
[0033] Figure 8 is the GCD diagram of the hard carbon composite material prepared in Example 1;
[0034] Figure 9 is the cycle life graph of the commercial hard carbon materials used;
[0035] Figure 10 This is a cycle life diagram of the hard carbon composite material prepared in Example 1. DETAILED DESCRIPTION
[0036] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Unless otherwise defined, all technical terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.
[0037] Hard carbon: Canrd, model: MA-EN-AN-0031; graphene oxide: Chongqing Yuntianhua Hanen New Materials Development Co., Ltd., sheet diameter 5-10 μm.
[0038] Example 1
[0039] A method for preparing a hard carbon composite material comprises the following steps:
[0040] (1) Dispersion of graphene oxide:
[0041] Weigh 20 g of graphene oxide and add it to 2 L of deionized water. Mechanically stir the mixture at a stirring rate of 1000 rpm for 60 min to prepare a graphene oxide dispersion, which is then set aside.
[0042] (2) Dispersion of hard carbon:
[0043] Weigh 200 g of hard carbon and add it to the graphene oxide dispersion in step (1). Mechanically stir the mixture at a stirring rate of 1200 rpm / min for 60 min to obtain a hard carbon / graphene oxide dispersion for later use.
[0044] (3) Drying of hard carbon / graphene oxide dispersion:
[0045] The hard carbon / graphene oxide dispersion prepared in step (2) was placed in a 50° C. forced air drying oven and dried for 24 h to obtain a hard carbon / graphene oxide composite for later use;
[0046] (4) Crushing of hard carbon / graphene oxide composite:
[0047] The hard carbon / graphene oxide composite obtained in step (3) was placed in a grinder and crushed for 3 minutes to obtain a hard carbon / graphene oxide composite powder for later use;
[0048] (5) Microwave treatment of hard carbon / graphene oxide composites:
[0049] 5 g of hard carbon / graphene oxide composite powder was weighed, placed in a quartz beaker, placed in a microwave oven in an air atmosphere, and microwaved at 800 W for 15 s to prepare a hard carbon composite material.
[0050] Example 2
[0051] A method for preparing a hard carbon composite material comprises the following steps:
[0052] (1) Dispersion of graphene oxide:
[0053] Weigh 20 g of graphene oxide and add it to 2 L of deionized water. Mechanically stir the mixture at a stirring rate of 1000 rpm / min for 80 min to prepare a graphene oxide dispersion, which is then set aside.
[0054] (2) Dispersion of hard carbon:
[0055] Weigh 200 g of hard carbon and add it to the graphene oxide dispersion of step (1). Mechanically stir the mixture at a stirring rate of 1200 rpm / min for 80 min to obtain a hard carbon / graphene oxide dispersion for later use.
[0056] (3) Drying of hard carbon / graphene oxide dispersion:
[0057] The hard carbon / graphene oxide dispersion prepared in step (2) was placed in a 50° C. forced air drying oven and dried for 24 h to obtain a hard carbon / graphene oxide composite for later use;
[0058] (4) Crushing of hard carbon / graphene oxide composite:
[0059] The hard carbon / graphene oxide composite obtained in step (3) was placed in a grinder and crushed for 4 minutes to obtain a hard carbon / graphene oxide composite powder for later use;
[0060] (5) Microwave treatment of hard carbon / graphene oxide composites:
[0061] 5 g of hard carbon / graphene oxide composite powder was weighed, placed in a quartz beaker, placed in a microwave oven in an air atmosphere, and microwaved at 800 W for 15 s to prepare a hard carbon composite material.
[0062] Example 3
[0063] A method for preparing a hard carbon composite material comprises the following steps:
[0064] (1) Dispersion of graphene oxide:
[0065] Weigh 20 g of graphene oxide and add it to 2 L of deionized water. Mechanically stir the mixture at a stirring rate of 1200 rpm / min for 60 min to prepare a graphene oxide dispersion for later use.
[0066] (2) Dispersion of hard carbon:
[0067] Weigh 200 g of hard carbon and add it to the graphene oxide dispersion of step (1). Mechanically stir the mixture at a stirring rate of 1400 rpm / min for 60 min to obtain a hard carbon / graphene oxide dispersion for later use.
[0068] (3) Drying of hard carbon / graphene oxide dispersion:
[0069] The hard carbon / graphene oxide dispersion prepared in step (2) was placed in a 50° C. forced air drying oven and dried for 24 h to obtain a hard carbon / graphene oxide composite for later use;
[0070] (4) Crushing of hard carbon / graphene oxide composite:
[0071] The hard carbon / graphene oxide composite obtained in step (3) was placed in a grinder and crushed for 3 minutes to obtain a hard carbon / graphene oxide composite powder for later use;
[0072] (5) Microwave treatment of hard carbon / graphene oxide composites:
[0073] 5 g of hard carbon / graphene oxide composite powder was weighed, placed in a quartz beaker, placed in a microwave oven in an air atmosphere, and microwaved at 700 W for 20 s to prepare a hard carbon composite material.
[0074] Example 4
[0075] A method for preparing a hard carbon composite material comprises the following steps:
[0076] (1) Dispersion of graphene oxide:
[0077] Weigh 16 g of graphene oxide and add it to 2 L of deionized water. Mechanically stir the mixture at a stirring rate of 1000 rpm / min for 60 min to prepare a graphene oxide dispersion, which is then set aside.
[0078] (2) Dispersion of hard carbon:
[0079] Weigh 200 g of hard carbon and add it to the graphene oxide dispersion of step (1). Mechanically stir the mixture at a stirring rate of 1200 rpm / min for 60 min to obtain a hard carbon / graphene oxide dispersion for later use.
[0080] (3) Drying of hard carbon / graphene oxide dispersion:
[0081] The hard carbon / graphene oxide dispersion prepared in step (2) was placed in a 50° C. forced air drying oven and dried for 30 h to obtain a hard carbon / graphene oxide composite for later use;
[0082] (4) Crushing of hard carbon / graphene oxide composite:
[0083] The hard carbon / graphene oxide composite obtained in step (3) was placed in a grinder and crushed for 3 minutes to obtain a hard carbon / graphene oxide composite powder for later use;
[0084] (5) Microwave treatment of hard carbon / graphene oxide composites:
[0085] 5 g of hard carbon / graphene oxide composite powder was weighed, placed in a quartz beaker, placed in a microwave oven in an air atmosphere, and microwaved at 800 W for 15 s to prepare a hard carbon composite material.
[0086] Example 5
[0087] A method for preparing a hard carbon composite material comprises the following steps:
[0088] (1) Dispersion of graphene oxide:
[0089] Weigh 16 g of graphene oxide and add it to 2 L of deionized water. Mechanically stir the mixture at a stirring rate of 1000 rpm / min for 60 min to prepare a graphene oxide dispersion, which is then set aside.
[0090] (2) Dispersion of hard carbon:
[0091] Weigh 200 g of hard carbon and add it to the graphene oxide dispersion of step (1). Mechanically stir the mixture at a stirring rate of 1400 rpm / min for 60 min to obtain a hard carbon / graphene oxide dispersion for later use.
[0092] (3) Drying of hard carbon / graphene oxide dispersion:
[0093] The hard carbon / graphene oxide dispersion prepared in step (2) was placed in a 50° C. forced air drying oven and dried for 30 h to obtain a hard carbon / graphene oxide composite for later use;
[0094] (4) Crushing of hard carbon / graphene oxide composite:
[0095] The hard carbon / graphene oxide composite obtained in step (3) was placed in a grinder and crushed for 5 minutes to obtain a hard carbon / graphene oxide composite powder for later use;
[0096] (5) Microwave treatment of hard carbon / graphene oxide composites:
[0097] 5 g of hard carbon / graphene oxide composite powder was weighed, placed in a quartz beaker, placed in a microwave oven in an air atmosphere, and microwaved at 800 W for 10 s to prepare a hard carbon composite material.
[0098] Comparative Example 1
[0099] (1) Dispersion of graphene oxide:
[0100] Weigh 20 g of graphene oxide and add it to 10 L of deionized water. Mechanically stir the mixture at a stirring rate of 1000 rpm / min for 60 min to prepare a graphene oxide dispersion for later use.
[0101] (2) Dispersion of hard carbon:
[0102] Weigh 200g of hard carbon and add it to the graphene oxide dispersion in the first step. Stir mechanically for 60min at a stirring rate of 1200rpm / min. The dispersion after stirring is shown in the following figure. Figure 5 , a large amount of hard carbon floats on the surface of the solution, indicating that low-concentration graphene oxide dispersion cannot disperse hard carbon.
[0103] Comparative Example 2
[0104] A method for preparing a hard carbon composite material comprises the following steps:
[0105] (1) Dispersion of graphene oxide:
[0106] Weigh 20 g of graphene oxide and add it to 2 L of deionized water. Mechanically stir the mixture at a stirring rate of 1000 rpm / min for 60 min to prepare a graphene oxide dispersion, which is then set aside.
[0107] (2) Dispersion of hard carbon:
[0108] Weigh 200 g of hard carbon and add it to the graphene oxide dispersion of step (1). Mechanically stir the mixture at a stirring rate of 1200 rpm / min for 60 min to obtain a hard carbon / graphene oxide dispersion for later use.
[0109] (3) Drying of hard carbon / graphene oxide dispersion:
[0110] The hard carbon / graphene oxide dispersion prepared in step (2) was placed in a 50° C. forced air drying oven and dried for 24 h to obtain a hard carbon / graphene oxide composite for later use;
[0111] (4) Crushing of hard carbon / graphene oxide composite:
[0112] The hard carbon / graphene oxide composite obtained in step (3) was placed in a grinder and crushed for 3 minutes to obtain a hard carbon / graphene oxide composite powder for later use;
[0113] (5) Microwave treatment of hard carbon / graphene oxide composites:
[0114] 5 g of hard carbon / graphene oxide composite powder was weighed, placed in a quartz beaker, placed in a microwave oven in an air atmosphere, and microwaved at 800 W for 15 min to prepare a hard carbon composite material.
[0115] Comparative Example 3
[0116] A method for preparing a hard carbon composite material comprises the following steps:
[0117] (1) Dispersion of graphene oxide:
[0118] Weigh 20 g of graphene oxide and add it to 2 L of deionized water. Mechanically stir the mixture at a stirring rate of 1000 rpm / min for 60 min to prepare a graphene oxide dispersion, which is then set aside.
[0119] (2) Dispersion of hard carbon:
[0120] Weigh 200 g of hard carbon and add it to the graphene oxide dispersion of step (1). Mechanically stir the mixture at a stirring rate of 1200 rpm / min for 60 min to obtain a hard carbon / graphene oxide dispersion for later use.
[0121] (3) Drying of hard carbon / graphene oxide dispersion:
[0122] The hard carbon / graphene oxide dispersion prepared in step (2) was placed in a 50° C. forced air drying oven and dried for 24 h to obtain a hard carbon / graphene oxide composite for later use;
[0123] (4) Crushing of hard carbon / graphene oxide composite:
[0124] The hard carbon / graphene oxide composite obtained in step (3) was placed in a grinder and crushed for 3 minutes to obtain a hard carbon / graphene oxide composite powder.
[0125] The specific composition of lithium-ion batteries is:
[0126] Negative electrode sheet: Using purchased commercial hard carbon and the negative electrode materials provided in the examples and comparative examples as the negative electrode active materials, the negative electrode active materials were mechanically mixed with a binder (PVDF) and a conductive agent (conductive carbon black) in a mass ratio of 8:1:1 to obtain a negative electrode slurry. The negative electrode slurry was coated on the surface of copper foil and dried at 80°C for 12 hours to obtain a negative electrode sheet;
[0127] Counter electrode: metal lithium sheet;
[0128] Electrolyte: EC, DMC and EMC were used as a mixed solvent in a volume ratio of 1:1:1, and LiPF6 was added to form a 1 mol / L LiPF6 electrolyte;
[0129] Diaphragm: 2320 separator, the main components include polyethylene (PE), aluminum oxide (as part of the ceramic coating) and polyvinylidene fluoride (PVDF);
[0130] Lithium-ion battery assembly: Assemble button-type lithium-ion batteries in an inert atmosphere glove box in the order of spring-gasket-negative electrode sheet-diaphragm-counter electrode sheet.
[0131] GCD test:
[0132] The assembled button lithium-ion battery was subjected to GCD test at a voltage range of 0-2.5V and a current density of 1A / g, and the coulombic efficiency was calculated based on the first charge and discharge cycle time, and the specific capacity was calculated based on the first discharge time.
[0133] Cyclic performance test:
[0134] The assembled button-type lithium-ion battery was subjected to 200 cycles of GCD testing at a voltage range of 0-2.5V and a current density of 1A / g. The capacity retention rate of the 200th cycle compared to the first cycle was calculated.
[0135] Figure 1 and Figure 2 The SEM images of the commercial hard carbon material raw material and the hard carbon composite material prepared in Example 1 are respectively Figure 1 It can be seen that commercial hard carbon is irregular micron particles with a relatively smooth surface. Figure 2 It can be seen that after being treated by the process of Example 1, its surface becomes rough and is wrapped with a tightly wrinkled film, indicating that the surface morphology of the commercial hard carbon has changed after treatment, and the graphene has completely and tightly wrapped it.
[0136] Figure 3 The XRD pattern of the hard carbon composite material prepared in Example 1 shows that typical diffraction peaks of hard carbon appear at 23.5 and 43.5 degrees, while a weak peak appears at around 10 degrees, which is the diffraction peak of graphene oxide. This shows that the process in Example 1 did not completely reduce the graphene oxide, fully ensuring that the hard carbon was not oxidized. Figure 4 It can be seen that O1s and C1s peaks appear, indicating that the obtained material is composed of C and O, indicating that the oxygen in graphene oxide is not fully transferred.
[0137] from Figure 5 It can be seen that a large amount of hard carbon floats on the surface of the solution, indicating that Comparative Example 1 cannot disperse the hard carbon in the aqueous solution. Figure 6 It can be seen from the graphene oxide dispersion that the hard carbon has been completely dispersed in the solution. Example 1 can effectively disperse the hard carbon. The concentration of the graphene oxide dispersion will affect the dispersion of the hard carbon. Figure 7 It can be seen that after the treatment of Comparative Example 2, the discharge capacity of the hard carbon active material is only 82 mAh / g, the charge capacity is 90 mAh / g, and the coulombic efficiency is 91%. Figure 8It can be seen that after the treatment in Example 1, the discharge capacity of the hard carbon active material reaches 220 mAh / g, the charge capacity is 220.5 mAh / g, and the coulombic efficiency is 100%. Figure 9 It can be seen that the first cycle discharge capacity of commercial hard carbon is only 113 mAh / g, and after 200 cycles the discharge capacity is only 48.6 mAh / g, with a capacity retention rate of only 43%. Figure 10 It can be seen that after the treatment in Example 1, the first cycle discharge capacity of the hard carbon material reaches 220 mAh / g, and the discharge capacity increases to 225 mAh / g after 200 cycles, with a capacity retention rate of >100%.
[0138] Table 1 Specific capacity and cycle performance of each sample
[0139]
[0140]
[0141] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.
Claims
1. A method for preparing a hard carbon composite material, characterized in that: The following steps are involved: (1) Dispersion of graphene oxide: Graphene oxide was added to deionized water and stirred to obtain a graphene oxide dispersion. (2) Dispersion of hard carbon: taking hard carbon, adding it to the graphene oxide dispersion obtained in step (1), stirring evenly, and preparing a hard carbon / graphene oxide dispersion; (3) Drying the hard carbon / graphene oxide dispersion: drying and crushing the hard carbon / graphene oxide dispersion to obtain a hard carbon / graphene oxide composite powder; (4) Microwave treatment of hard carbon / graphene oxide composite: Put the hard carbon / graphene oxide composite powder into a microwave oven and microwave treat it for a period of time to obtain a hard carbon composite material.
2. The method for preparing a hard carbon composite material according to claim 1, wherein: The sheet diameter of the graphene oxide is 5 to 10 μm.
3. The method for preparing a hard carbon composite material according to claim 1, wherein: In the step (1), the stirring rate is 800-1000 rpm, and the stirring time is 60-90 min.
4. The method for preparing a hard carbon composite material according to claim 1, wherein: The graphene oxide concentration in the graphene oxide dispersion is 8 to 12 g / L.
5. The method for preparing a hard carbon composite material according to claim 1, wherein: In the step (2), the mass ratio of hard carbon to graphene oxide is 8:1 to 13:
1.
6. The method for preparing a hard carbon composite material according to claim 1, wherein: In the step (2), the stirring rate is 1200-1400 rpm, and the stirring time is 60-90 min.
7. The method for preparing a hard carbon composite material according to claim 1, wherein: In the step (3), the drying temperature is 50 to 80° C., and the drying time is 24 to 30 hours.
8. The method for preparing a hard carbon composite material according to claim 1, wherein: In the step (4), microwave treatment is carried out in an air atmosphere, the microwave power is 600 to 800 W, and the microwave time is 10 to 20 seconds.
9. A hard carbon composite material, characterized in that The hard carbon composite material is prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the hard carbon composite material according to claim 9 in preparing battery negative electrode materials.