Novel graphite negative electrode material and preparation method and application thereof

Abstract

The embodiment of the invention relates to a novel graphite negative electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: carrying out first heat treatment on a metal organic framework material MOFs in an inert atmosphere to carbonize the MOFs to obtain a carbon-based material of which the skeleton contains metal particles and / or a metal compound; carrying out second heat treatment on the carbon-based material in an inert atmosphere so as to rearrange carbon in the carbon-based material to form a graphite structure and obtain a graphite material containing metal particles and / or a metal compound; pickling the graphite material to enable the metal to react with an acid solution to obtain a porous graphite material; and washing, centrifuging and drying the porous graphite material to obtain the novel graphite negative electrode material with a pore structure.

Description

Technical Field

[0001] The present invention relates to the field of secondary battery materials, and particularly to a novel graphite anode material, a preparation method thereof, and an application thereof. Background Art

[0002] In the development process of lithium-ion batteries, there is a milestone node, which is the application of graphite anodes. Graphite has become the mainstream anode material due to its advantages such as low charge-discharge platform, stable cycling, wide source, and rich reserves. Since the development of lithium-ion batteries to date, various cathode material systems such as lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide have been derived, but the graphite-based anode material system has been used until now.

[0003] Due to the limitation of the endurance of lithium-ion batteries, in order to meet the needs of users in a timely manner, fast charging has become one of the ways to solve the problem of insufficient endurance of lithium-ion batteries. However, during the fast charging process, some disadvantages of graphite anodes are particularly prominent: due to the poor stability of the layered structure of graphite, during the charge-discharge process, when lithium ions are inserted and extracted, the structure of the graphite layer will change, resulting in a serious decrease in the specific capacity of the battery and a significant shortening of the energy storage life; in addition, the rate performance of graphite anodes is poor and cannot meet the requirements of fast charging.

[0004] The pore structure on the surface of graphite is an important factor determining the lithium insertion capacity of graphite. Therefore, in order to improve the fast insertion / extraction performance of graphite anodes, the above problems can be alleviated by increasing the pore structure of graphite materials.

[0005] Currently, the methods for creating pore structures in graphite are only limited to coating graphite or performing metal modification on the end faces and layered surfaces of graphite. However, the above methods do not change the inherent properties of graphite materials. Therefore, a new method for creating pores in graphite is needed to make the pores evenly distributed in the graphite material. Summary of the Invention

[0006] The object of the present invention is to address the defects existing in the prior art and provide a novel graphite anode material, a preparation method thereof, and an application thereof. The preparation method uses MOFs as the starting material and utilizes the advantages of large specific surface area, high porosity, regular pore structure, and adjustable pore structure of MOFs. Through two heat treatments and acidification treatments, a novel graphite anode material with a pore structure is obtained. This preparation method is a method for creating pores in the graphite material itself, and the pore structure is evenly distributed in the graphite material.

[0007] To achieve the above object, in the first aspect, the present invention provides a preparation method for a novel graphite anode material, and the preparation method includes:

[0008] Under an inert atmosphere, the metal-organic framework material MOFs is subjected to a first heat treatment to carbonize the MOFs, obtaining a carbon-based material containing metal particles and / or metal compounds in the framework;

[0009] Under the inert atmosphere, the carbon-based material is subjected to a second heat treatment to rearrange the carbon in the carbon-based material to form a graphite structure, obtaining a graphite material containing metal particles and / or metal compounds;

[0010] The graphite material is pickled so that the metal particles and / or metal compounds react with the acid solution, obtaining a porous graphite material;

[0011] The porous graphite material is washed with water, centrifuged, and dried to obtain a novel graphite anode material with a pore structure.

[0012] Preferably, the MOFs includes one or more of reticular metal-organic framework materials IRMOFs, zeolitic imidazolate framework materials ZIFs, lewisite framework materials MIls, pore-channel framework materials PCNs, UIO series materials, NU series materials, HKUIST series materials.

[0013] Preferably, the temperature of the first heat treatment is 300°C - 600°C, and the time is 10 min - 120 min; the temperature of the second heat treatment is 800°C - 1400°C, and the time is 1 hour - 24 hours.

[0014] Preferably, the acid solution for pickling is one or more of hydrochloric acid, nitric acid, sulfuric acid, and hydrofluoric acid; the mass fraction of the acid solution is 10% - 20%.

[0015] Preferably, the temperature of pickling is 10°C - 80°C, and the time is 1 hour - 48 hours.

[0016] Preferably, the particle size of the novel graphite anode material is 30 nm - 5000 nm, the pore diameter is 0.3 nm - 6 nm, the pore volume is 0.1 cm 3 / g - 4 cm 3 / g, the specific surface area is 50 m 2 / g - 1800 m 2 / g, and the intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is 0.2 - 1.0.

[0017] In a second aspect, the present invention provides a novel graphite anode material, and the novel graphite anode material is prepared by the preparation method described in any one of the first aspects above.

[0018] In a third aspect, the present invention provides a negative electrode sheet, and the negative electrode sheet includes the novel graphite anode material described in the second aspect.

[0019] Preferably, the negative electrode sheet comprises a silicon-carbon material formed by the composite of the novel graphite negative electrode material and silicon, or a sulfur-carbon material formed by the composite of the novel graphite negative electrode material and sulfur.

[0020] Fourthly, the present invention provides a secondary battery, which comprises the negative electrode sheet described in the third aspect.

[0021] The preparation method of the novel graphite negative electrode material provided by the embodiment of the present invention uses MOFs as the starting material and performs two heat treatments and acidification treatments on it. Among them, the first heat treatment can make the organic framework of MOFs form a carbon matrix, and the metal centers form metal particles and / or metal compound particles, which are uniformly distributed in the carbon matrix, providing conditions for the second heat treatment and subsequent acidification; the second heat treatment makes the carbon matrix further graphitized, which not only retains the porous structure of the MOFs material, overcomes the problem of poor stability of the graphite layered structure, but also improves the conductivity. Finally, the metal particles and / or metal compound particles are removed by pickling treatment, so that the novel graphite negative electrode material has a pore structure. This pore structure is uniformly and comprehensively distributed in the graphite material. The high specific surface area of MOFs itself and the pore structure left after the removal of metals and metal compounds make the novel graphite negative electrode material have the characteristics of high specific surface area and multi-micropores. When it is applied to a lithium-ion battery, it is beneficial to the deintercalation, transmission and storage of lithium ions, can improve the specific capacity and rate performance of the lithium-ion battery, and meets the requirements of rapid charging of the lithium-ion battery. Description of the Drawings

[0022] Figure 1 It is a flow chart of the preparation method of the novel graphite negative electrode material provided by the embodiment of the present invention. Detailed Embodiments

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] The technical solutions of the present invention will be further described in detail below through the drawings and embodiments.

[0025] The embodiment of the present invention provides a preparation method of a novel graphite negative electrode material, and the process is as Figure 1 shown, including the following steps:

[0026] Step 110: Under an inert atmosphere, perform the first heat treatment on the metal-organic framework material (MOFs) to carbonize the MOFs and obtain a carbon-based material containing metal particles and / or metal compounds in the framework.

[0027] Among them, the inert atmosphere is specifically helium and / or argon.

[0028] The metal-organic framework material (Metal organic Framework, MOFs) is neither the same as inorganic porous materials nor general organic complexes, and has both the rigidity of inorganic materials and the flexibility of organic materials. It has the advantages of a large specific surface area, high porosity, regular pore structure, and adjustable pore structure, etc., making its application in energy storage have great advantages. For example, the pore structure of MOFs provides sufficient storage space for ions or gases; the pore size and pore surface can be regulated, and the unsaturated metal sites in MOFs can serve as catalytic centers, providing good basic conditions for subsequent graphitization and acidification to create pores.

[0029] In this application, the MOFs can specifically include one or more of isoreticular metal-organic frameworks (IRMOFs), zeolitic imidazolate frameworks (ZIFs), material sof mstitute lavoisier frameworks (MIls), pocket-channel frameworks (PCNs), UIO (University of Oslo) series materials, NU (Northwestern University) series materials, and HKUIST (Hongkong University) series materials.

[0030] The first heat treatment can be carried out in a tube furnace, the temperature can be 300°C - 600°C, preferably 400°C - 500°C, and the time can be 10 min - 120 min, preferably 60 min - 90 min.

[0031] The first heat treatment carbonizes the MOFs. During this process, the carbon atoms in the organic ligands of the MOFs will rearrange inside the particles, and a carbon matrix with a higher specific surface area will be synthesized on the basis of the original organic framework. At the same time, some or all of the metal centers can combine with oxygen ions, nitrogen ions, etc. released during the carbon atom rearrangement to form metal compound particles, and some metal centers directly exist in the form of metal particles. The carbon matrix can prevent the aggregation of metal particles and / or metal compound particles, making the metal particles and / or metal compound particles evenly distributed in the carbon matrix. At the same time, the uniform distribution of the metal particles and / or metal compound particles in the carbon matrix also plays a supporting role in the MOFs structure. After the first heat treatment, the conductivity of the MOFs is greatly improved, overcoming the disadvantage of poor conductivity of the MOFs.

[0032] Step 120, under an inert atmosphere, perform a second heat treatment on the carbon-based material to cause the carbon in the carbon-based material to rearrange to form a graphite structure, obtaining a graphite material containing metal particles and / or metal compounds;

[0033] Specifically, the second heat treatment can be carried out in a high-temperature furnace, the temperature is specifically 800°C - 1400°C, preferably 900°C - 1200°C, and the time is specifically 1 hour - 24 hours, preferably 10 - 18 hours.

[0034] The second heat treatment is mainly the further rearrangement of carbon atoms, making the arrangement of carbon atoms more orderly, forming a structure similar to graphite, and at the same time reducing the relatively large specific surface area of the MOFs material to prevent the decline of the electrochemical performance of the material caused by the large specific surface area. However, due to the first heat treatment, the metal and / or metal compound particles are evenly distributed in the carbon matrix and play a supporting role in the structure of the carbon matrix. Therefore, during the second heat treatment, the rearrangement of the carbon matrix will not cause the collapse of the structure. And because the starting material is MOFs nanoparticles, the first heat treatment and the second heat treatment are equivalent to in-situ carbonization and graphitization, and the obtained graphite material is nanoparticles. In this way, the porous structure of the MOFs particles is retained, the problem of poor stability of the graphite layered structure is overcome, and at the same time, the conductivity is improved, which helps to improve the energy storage specific capacity and kinetic behavior of the material.

[0035] Step 130, perform pickling on the graphite material to cause the metal particles and / or metal compounds to react with the acid solution, obtaining a porous graphite material;

[0036] Specifically, the acid solution for pickling can be one or more of hydrochloric acid, nitric acid, sulfuric acid, and hydrofluoric acid. To ensure that all metals and metal compounds are converted into salts, the acid solution needs to be in excess. The mass fraction of the acid solution can be 10%-20%. The temperature for pickling is specifically 10°C - 80°C, preferably 20°C - 35°C, and the time is specifically 1 hour - 48 hours, preferably 10 hours - 30 hours.

[0037] The pickling process is mainly to remove metals and metal compounds, leaving pore structures at the positions of the metals and / or metal compounds, thereby achieving the purpose of creating pores in the graphite. Since the metals and / or metal compounds are uniformly distributed in the graphite structure, the pore structures left after pickling are also uniformly distributed and throughout the entire graphite structure, rather than just on the surface of the graphite.

[0038] Step 140: Wash, centrifuge, and dry the porous graphite material to obtain a novel graphite anode material with a pore structure.

[0039] Specifically, the number of times of washing can be 3 - 8 times, preferably 4 - 6 times. The purpose of washing is to remove residual impurities on the one hand and dilute and remove the unreacted acid on the other hand. The rotation speed for centrifugation can specifically be 5000 revolutions per minute - 10000 revolutions per minute, and the time is 6 minutes - 9 minutes. Drying can further volatilize the moisture and the remaining acid. Drying can specifically be carried out in an oven, the temperature can be 80°C - 100°C, preferably 90°C, and the time can be 6 hours - 24 hours, preferably 12 hours - 18 hours.

[0040] Since the starting material MOFs are nanoparticles, the obtained novel graphite anode material has a comprehensive, uniform, and controllable pore structure and is a particulate graphite anode material. The particle size of the novel graphite anode material is specifically 30nm - 5000nm, the pore diameter is specifically 0.3nm - 6nm, the pore volume is specifically 0.1 cm 3 / g - 4 cm 3 / g, the specific surface area is specifically 50 m 2 / g - 1800 m 2 / g, and the intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.2 - 1.0. The pore structure is uniformly and comprehensively distributed in the graphite. The pore diameter of the pore structure is determined by the pore diameter of the MOFs, the size of the metal and metal compound particles, and the treatment process. Therefore, the pore creation process in this application is controllable.

[0041] The preparation method of the novel graphite anode material provided by the embodiment of the present invention uses MOFs as the starting material and performs two heat treatments and acidification treatments on it. Among them, the first heat treatment can form a carbon matrix from the organic framework of MOFs, and the metal centers form metal particles and / or metal compound particles, which are uniformly distributed in the carbon matrix, providing conditions for the second heat treatment and subsequent acidification; the second heat treatment further graphitizes the carbon matrix, which not only retains the porous structure of the MOFs material, overcomes the problem of poor stability of the graphite layered structure, but also improves the conductivity. Finally, the metal particles and / or metal compound particles are removed by pickling treatment, so that the novel graphite anode material has a pore structure. This pore structure is uniformly and comprehensively distributed in the graphite material. The high specific surface area of MOFs itself and the pore structure left after the removal of metals and metal compounds endow the novel graphite anode material with the characteristics of a high specific surface area and multiple micropores. When it is applied to lithium-ion batteries, it is beneficial to the insertion and extraction, transmission and storage of lithium ions, can improve the specific capacity and rate performance of lithium-ion batteries, and meets the requirements of rapid charging of lithium-ion batteries.

[0042] The novel graphite anode material provided by the embodiment of the present invention can be applied in the electrode materials of secondary batteries, and the secondary batteries include but are not limited to lithium-ion batteries and sodium-ion batteries.

[0043] The novel graphite anode material can be directly used as the anode active material for the anode of secondary batteries. It can also be used as a carrier for preparing the anode electrode sheet of secondary batteries. For example, it can be compounded with silicon by methods such as chemical vapor deposition to form a silicon-carbon material for preparing the anode electrode sheet, where silicon is deposited in the pore structure of the novel graphite anode material. Or, the novel graphite anode material provided by the embodiment of the present invention can be compounded with sulfur by methods such as chemical vapor deposition to form a sulfur-carbon material for preparing the anode electrode sheet, where sulfur is deposited in the pore structure of the novel graphite anode material.

[0044] To better understand the technical solution provided by the present invention, the following uses multiple specific examples to separately illustrate the specific process of preparing the novel graphite anode material by using the method provided in the above embodiments of the present invention, and the electrochemical characteristics of the prepared novel graphite anode material.

[0045] Example 1

[0046] In the first step, under a helium atmosphere, 5 g of MOF-303(Al) material is placed in a tubular furnace and treated at a temperature of 300 °C for 120 min. After cooling, a carbon-based material containing aluminum particles and / or aluminum compounds in the framework is obtained.

[0047] In the second step, the carbon-based material is transferred to a high-temperature furnace and calcined at 800 °C for 6 hours under a helium atmosphere. After cooling, a graphite material containing aluminum particles and / or aluminum compounds is obtained.

[0048] In the third step, 30 g of 10% hydrochloric acid by mass is added to the graphite material for pickling to obtain a porous graphite material. The pickling temperature is 25 °C and the time is 5 hours.

[0049] In the fourth step, the porous graphite material is washed with water and then centrifuged at a speed of 5000 revolutions per minute for 9 minutes, and this is repeated three times. The centrifuged product is placed in a drying oven and dried at 80 °C for 6 hours to obtain a novel graphite anode material. The particle size of the novel graphite anode material is 412 nm, the pore diameter is 0.6 nm, the pore volume is 0.33 cm 3 / g, and the specific surface area is 391 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.38.

[0050] After that, a pole piece of a lithium-ion battery is prepared using the obtained novel graphite anode material, and a coin-type half-cell is assembled using this pole piece for testing, as follows:

[0051] First, the novel graphite anode material, conductive agent carbon black, and binder are added to deionized water and mixed evenly according to a mass ratio of 95:2:3. The binder is sodium carboxymethyl cellulose and styrene-butadiene rubber, and the mass ratio of sodium carboxymethyl cellulose to styrene-butadiene rubber is 10:8. A slurry is prepared using a pulper, coated on a copper foil with a coating thickness of 220 μm to obtain a pole piece, dried at 55 °C for 2 hours, cut into a circular pole piece with a diameter of 14 mm, and then dried in a vacuum drying oven at 100 °C for 8 hours.

[0052] Second, the above-mentioned pole piece is assembled into a coin-type half-cell in an argon-filled glove box. The electrolyte of the coin-type half-cell is 1 mol / L lithium hexafluorophosphate LiPF6, the solvent of the electrolyte is ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl phosphate (DEC), and the volume ratio of EC, DMC, and DEC is 1:1:1. The counter electrode is a lithium sheet. The separator is a polyethylene separator.

[0053] Then, a constant current charge-discharge test is performed using a charge-discharge instrument. The test conditions are: the discharge cut-off voltage is 0.005 V, and the charge cut-off voltage is 2 V. First, the charge specific capacity is tested at a current density of 0.1 C, and then the rate performance is tested at current densities of 1C / 2C / 3C / 4C / 5C.

[0054] Example 2

[0055] First step, under a helium atmosphere, place 24 g of PCN-128(Zr) material in a tubular furnace, treat it at a temperature of 500 °C for 60 min, and after cooling, obtain a carbon-based material containing zircon particles and / or zircon compounds in the framework.

[0056] Second step, transfer the carbon-based material to a high-temperature furnace, calcine it at a temperature of 1000 °C for 18 hours under a helium atmosphere, and after cooling, obtain a graphite material containing zircon particles and / or zircon compounds.

[0057] Third step, take 15 g of 10% hydrochloric acid and 13 g of 10% nitric acid, add them to the graphite material, and perform acid washing on it to obtain a porous graphite material. Among them, the temperature of acid washing is 55 °C and the time is 24 hours.

[0058] Fourth step, wash the porous graphite material with water, then centrifuge it at a speed of 10,000 revolutions per minute for 6 minutes, and repeat this four times. Place the centrifuged product in an oven and dry it at a temperature of 100 °C for 6 hours to obtain a novel graphite anode material. Among them, the particle size of the novel graphite anode material is 592 nm, the pore size is 2.7 nm, the pore volume is 1.2 cm 3 / g, and the specific surface area is 1231 m 2 / g, and the intensity ratio ID / IG of the D peak and G peak in the Raman spectrum is specifically 0.55.

[0059] After that, use the prepared novel graphite anode material to prepare the electrode sheet of a lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0060] Example 3

[0061] First step, under a helium atmosphere, place 10 g of MOF-801(Zr) material in a tubular furnace, treat it at a temperature of 600 °C for 30 min, and after cooling, obtain a carbon-based material containing zircon particles and / or zircon compounds in the framework.

[0062] Second step, transfer the carbon-based material to a high-temperature furnace, calcine it at a temperature of 1200 °C for 16 hours under a helium atmosphere, and after cooling, obtain a graphite material containing zircon particles and / or zircon compounds.

[0063] Third step, take 8 g of 20% hydrochloric acid and 6 g of 20% nitric acid, add them to the graphite material, and perform acid washing on it to obtain a porous graphite material. Among them, the temperature of acid washing is 35 °C and the time is 12 hours.

[0064] Step 4: Wash the porous graphite material, then centrifuge it at a speed of 6000 revolutions per minute for 8 minutes, and repeat this five times. Place the centrifuged product in an oven and dry it at a temperature of 90 °C for 12 hours to obtain a novel graphite anode material. Among them, the particle size of the novel graphite anode material is 362 nm, the pore diameter is 0.51 nm, and the pore volume is 0.35 cm 3 / g, and the specific surface area is 722 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.79.

[0065] After that, use the prepared novel graphite anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0066] Example 4

[0067] Step 1: Under an argon atmosphere, place 15 g of MOF-808(Zr) material in a tube furnace and treat it at a temperature of 450 °C for 90 min. After cooling, obtain a carbon-based material containing zircon particles and / or zircon compounds in the framework.

[0068] Step 2: Transfer the carbon-based material to a high-temperature furnace and calcine it at a temperature of 1400 °C for 10 hours under a helium atmosphere. After cooling, obtain a graphite material containing zircon particles and / or zircon compounds.

[0069] Step 3: Take 4 g of hydrochloric acid with a mass fraction of 20%, 6 g of nitric acid with a mass fraction of 20%, and 2 g of hydrofluoric acid with a mass fraction of 20%, add them to the graphite material, and perform acid washing on it to obtain a porous graphite material. Among them, the temperature of the acid washing is 25 °C and the time is 8 hours.

[0070] Step 4: Wash the porous graphite material, then centrifuge it at a speed of 8000 revolutions per minute for 7 minutes, and repeat this five times. Place the centrifuged product in an oven and dry it at a temperature of 90 °C for 18 hours to obtain a novel graphite anode material. Among them, the particle size of the novel graphite anode material is 482 nm, the pore diameter is 1.52 nm, and the pore volume is 0.51 cm 3 / g, and the specific surface area is 1290 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.68.

[0071] After that, use the prepared novel graphite anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0072] Example 5

[0073] First step, under an argon atmosphere, place 5 g of MOF-74(Mg) material in a tubular furnace, treat it at a temperature of 400 °C for 120 min, and after cooling, obtain a carbon-based material containing magnesium particles and / or magnesium compounds in the framework.

[0074] Second step, transfer the carbon-based material to a high-temperature furnace, calcine it at a temperature of 1100 °C for 16 hours under an argon atmosphere, and after cooling, obtain a graphite material containing magnesium particles and / or magnesium compounds.

[0075] Third step, take 3 g of hydrochloric acid with a mass fraction of 15% and 12 g of nitric acid with a mass fraction of 15%, add them to the graphite material, and perform acid washing on it to obtain a porous graphite material. Among them, the temperature of acid washing is 20 °C and the time is 20 hours.

[0076] Fourth step, wash the porous graphite material with water, then centrifuge it at a speed of 9000 revolutions per minute for 9 minutes, and repeat this six times. Place the centrifuged product in an oven and dry it at a temperature of 80 °C for 24 hours to obtain a novel graphite anode material. Among them, the particle size of the novel graphite anode material is 1840 nm, the pore size is 0.8 nm, the pore volume is 0.41 cm 3 / g, and the specific surface area is 884 m 2 / g. The intensity ratio ID / IG of the D peak and G peak in the Raman spectrum is specifically 0.96.

[0077] After that, use the prepared novel graphite anode material to prepare the electrode sheet of a lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0078] Example 6

[0079] First step, under an argon atmosphere, place 10 g of HKUST-1(Cu) material in a tubular furnace, treat it at a temperature of 300 °C for 120 min, and after cooling, obtain a carbon-based material containing copper particles and / or copper compounds in the framework.

[0080] Second step, transfer the carbon-based material to a high-temperature furnace, calcine it at a temperature of 900 °C for 20 hours under an argon atmosphere, and after cooling, obtain a graphite material containing copper particles and / or copper compounds.

[0081] Third step, take 22 g of hydrochloric acid with a mass fraction of 15%, add it to the copper-graphite material, and perform acid washing on it to obtain a porous graphite material. Among them, the temperature of acid washing is 25 °C and the time is 24 hours.

[0082] Step 4: Wash the porous graphite material, then centrifuge it at a speed of 9000 revolutions per minute for 9 minutes, and repeat this seven times. Place the centrifuged product in an oven and dry it at 80 °C for 12 hours to obtain a novel graphite anode material. Among them, the particle size of the novel graphite anode material is 837 nm, the pore diameter is 0.71 nm, and the pore volume is 0.19 cm 3 / g, and the specific surface area is 922 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 1.10.

[0083] After that, use the prepared novel graphite anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0084] Example 7

[0085] Step 1: Under an argon atmosphere, place 10 g of MIL-101(Cr) material in a tubular furnace and treat it at 500 °C for 120 min. After cooling, obtain a carbon-based material containing chromium particles and / or chromium compounds in the framework.

[0086] Step 2: Transfer the carbon-based material to a high-temperature furnace and calcine it at 1000 °C for 18 hours under an argon atmosphere. After cooling, obtain a graphite material containing chromium particles and / or chromium compounds.

[0087] Step 3: Take 13 g of hydrochloric acid with a mass fraction of 15% and 5 g of nitric acid with a mass fraction of 15%, add them to the graphite material, and perform pickling on it to obtain a porous graphite material. Among them, the pickling temperature is 70 °C and the time is 24 hours.

[0088] Step 4: Wash the porous graphite material, then centrifuge it at a speed of 7000 revolutions per minute for 9 minutes, and repeat this eight times. Place the centrifuged product in an oven and dry it at 85 °C for 15 hours to obtain a novel graphite anode material. Among them, the particle size of the novel graphite anode material is 490 nm, the pore diameter is 1.3 nm, and the pore volume is 1.8 cm 3 / g, and the specific surface area is 1840 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.37.

[0089] After that, use the prepared novel graphite anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0090] Example 8

[0091] First step, under a nitrogen atmosphere, place 15 g of MIL-100(Fe) material in a tubular furnace and treat it at a temperature of 500 °C for 80 min. After cooling, a carbon-based material containing iron particles and / or iron compounds in the framework structure is obtained.

[0092] Second step, transfer the carbon-based material to a high-temperature furnace and calcine it at a temperature of 950 °C for 14 hours under an argon atmosphere. After cooling, a graphite material containing iron particles and / or iron compounds is obtained.

[0093] Third step, take 22 g of hydrochloric acid with a mass fraction of 20% and add it to the iron-graphite material for pickling to obtain a porous graphite material. Among them, the pickling temperature is 20 °C and the time is 4 hours.

[0094] Fourth step, wash the porous graphite material with water, then centrifuge it at a speed of 8000 revolutions per minute for 8 minutes, and repeat this three times. Place the centrifuged product in an oven and dry it at a temperature of 95 °C for 18 hours to obtain a novel graphite anode material. Among them, the particle size of the novel graphite anode material is 190 nm, the pore diameter is 2.1 nm, the pore volume is 0.6 cm 3 / g, and the specific surface area is 1231 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.55.

[0095] After that, use the prepared novel graphite anode material to prepare the electrode sheet of a lithium-ion battery, and assemble a button-type half-cell with this electrode sheet for testing. The assembly and testing process of the button-type half-cell are the same as those in Example 1.

[0096] Example 9

[0097] First step, under an argon atmosphere, place 5 g of ZIF-8(Zn) material in a tubular furnace and treat it at a temperature of 400 °C for 90 min. After cooling, a carbon-based material containing zinc particles and / or zinc compounds in the framework is obtained.

[0098] Second step, transfer the carbon-based material to a high-temperature furnace and calcine it at a temperature of 850 °C for 12 hours under an argon atmosphere. After cooling, a graphite material containing zinc particles and / or zinc compounds is obtained.

[0099] Third step, take 10 g of hydrochloric acid with a mass fraction of 15% and add it to the graphite material for pickling to obtain a porous graphite material. Among them, the pickling temperature is 25 °C and the time is 10 hours.

[0100] Step 4: Wash the porous graphite material, then centrifuge it at a speed of 8000 revolutions per minute for 8 minutes, and repeat this four times. Place the centrifuged product in an oven and dry it at a temperature of 100 °C for 10 hours to obtain the novel graphite anode material. Among them, the particle size of the novel graphite anode material is 390 nm, the pore size is 0.81 nm, the pore volume is 0.42 cm 3 / g, and the specific surface area is 931 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.89.

[0101] After that, use the prepared novel graphite anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0102] Example 10

[0103] Step 1: Under an argon atmosphere, place 5 g of UIO-66-F4(Zr) material in a tubular furnace and treat it at a temperature of 300 °C for 90 min. After cooling, obtain a carbon-based material containing zircon particles and / or zircon compounds.

[0104] Step 2: Transfer the carbon-based material to a high-temperature furnace and calcine it at a temperature of 900 °C for 15 hours under a nitrogen atmosphere. After cooling, obtain a graphite material containing zircon particles and / or zircon compounds.

[0105] Step 3: Take 11 g of hydrochloric acid with a mass fraction of 20%, add it to the graphite material, and perform pickling on it to obtain a porous graphite material. Among them, the pickling temperature is 25 °C and the time is 16 hours.

[0106] Step 4: Wash the porous graphite material, then centrifuge it at a speed of 6500 revolutions per minute for 9 minutes, and repeat this five times. Place the centrifuged product in an oven and dry it at a temperature of 95 °C for 16 hours to obtain the novel graphite anode material. Among them, the particle size of the novel graphite anode material is 283 nm, the pore size is 0.58 nm, the pore volume is 0.32 cm 3 / g, and the specific surface area is 531 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is specifically 0.6.

[0107] After that, use the prepared novel graphite anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0108] Comparative Example 1

[0109] First step, under a helium atmosphere, place 5 g of MOF-303(Al) material in a tube furnace, and treat it at a temperature of 300 °C for 120 min. After cooling, a carbon-based material containing aluminum particles and / or aluminum compounds in the framework is obtained.

[0110] Second step, take 30 g of hydrochloric acid with a mass fraction of 10%, add it to the carbon-based material, and perform pickling on it to obtain a porous carbon-based material. Among them, the pickling temperature is 25 °C and the time is 5 hours.

[0111] Fourth step, wash the porous carbon-based material with water, and then centrifuge it at a speed of 5000 revolutions per minute for 9 minutes, repeating this three times. Place the centrifuged product in an oven and dry it at a temperature of 80 °C for 6 hours to obtain a carbon-based anode material with a pore structure. Among them, the particle size of the carbon-based anode material is 477 nm, the pore diameter is 0.8 nm, the pore volume is 0.46 cm 3 / g, and the specific surface area is 561 m 2 / g, and no graphite structure is formed.

[0112] After that, use the prepared carbon-based anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0113] Comparative Example 2

[0114] First step, under a helium atmosphere, place 5 g of MOF-303(Al) material in a high-temperature furnace, and calcine it at a temperature of 800 °C for 6 hours under a helium atmosphere. After cooling, a graphite material containing aluminum particles and / or aluminum compounds is obtained.

[0115] Second step, take 30 g of hydrochloric acid with a mass fraction of 10%, add it to the graphite material, and perform pickling on it to obtain a porous graphite material. Among them, the pickling temperature is 25 °C and the time is 5 hours.

[0116] Third step, wash the porous graphite material with water, and then centrifuge it at a speed of 5000 revolutions per minute for 9 minutes, repeating this three times. Place the centrifuged product in an oven and dry it at a temperature of 80 °C for 6 hours to obtain a new type of graphite anode material. Among them, the particle size of the new type of graphite anode material is 220 nm, the pore diameter is 0.12 nm, the pore volume is 0.19 cm 3 / g, and the specific surface area is 73 m 2 / g, and no graphite structure is formed.

[0117] After that, use the prepared new type of graphite anode material to prepare the electrode sheet of the lithium-ion battery, and use this electrode sheet to assemble a coin-type half-cell for testing. The assembly and testing process of the coin-type half-cell are the same as those in Example 1.

[0118] Table 1 shows the electrochemical performance test data of the coin-type half-cells of the above Examples 1-10 and Comparative Examples 1-2.

[0119]

[0120] As can be seen from Table 1, compared with Comparative Examples 1 and 2, the novel graphite anode material prepared in the examples of the present invention has a higher first-cycle charge specific capacity and better rate performance. This is because the novel graphite anode material of the present invention has undergone two heat treatments and acidification treatments on the MOFs particles, achieving the purpose of creating a pore structure in the graphite material itself, increasing the specific surface area of the graphite material, and at the same time overcoming the problem of low conductivity of MOFs. It can be seen from Comparative Example 1 that without the second heat treatment, the charge specific capacity of the material is significantly reduced. It can be seen from Comparative Example 2 that due to the lack of the first heat treatment and the direct implementation of the second heat treatment, the structure of MOFs will collapse, resulting in a reduction in the number of micropores and a significant decrease in the specific surface area, leading to a decline in specific capacity and rate performance.

[0121] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, 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 preparation method of a novel graphite anode material, characterized in that The preparation method includes the following steps: Under an inert atmosphere, perform a first heat treatment on the metal-organic framework material (MOFs) to carbonize the MOFs, obtaining a carbon-based material containing metal particles and / or metal compounds in the framework; Under the inert atmosphere, perform a second heat treatment on the carbon-based material to rearrange the carbon in the carbon-based material to form a graphite structure, obtaining a graphite material containing metal particles and / or metal compounds; Perform pickling on the graphite material to cause the metal particles and / or metal compounds to react with the acid solution, obtaining a porous graphite material; Perform water washing, centrifugation, and drying on the porous graphite material to obtain a novel graphite anode material with a pore structure.

2. The preparation method according to claim 1, characterized in that, The MOFs include one or more of reticular metal-organic framework materials (IRMOFs), zeolitic imidazolate framework materials (ZIFs), LeVail structure materials (MIls), pore-channel framework materials (PCNs), UIO series materials, NU series materials, and HKUIST series materials.

3. The preparation method according to claim 1, characterized in that, The temperature of the first heat treatment is 300°C - 600°C, and the time is 10 min - 120 min; the temperature of the second heat treatment is 800°C - 1400°C, and the time is 1 hour - 24 hours.

4. The preparation method according to claim 1, characterized in that, The acid solution for pickling is one or more of hydrochloric acid, nitric acid, sulfuric acid, and hydrofluoric acid; the mass fraction of the acid solution is 10% - 20%.

5. The preparation method according to claim 1, wherein The temperature of pickling is 10°C - 80°C, and the time is 1 hour - 48 hours.

6. The preparation method according to claim 1, characterized in that, The particle size of the novel graphite anode material is 30 nm - 5000 nm, the pore diameter is 0.3 nm - 6 nm, the pore volume is 0.1 cm 3 / g - 4 cm 3 / g, and the specific surface area is 50 m 2 / g - 1800 m 2 / g. The intensity ratio ID / IG of the D peak to the G peak in the Raman spectrum is 0.2 - 1.

0.

7. A novel graphite anode material, characterized in that, The novel graphite anode material is prepared by the preparation method according to any one of claims 1 - 6 above.

8. A negative electrode plate, characterized in that, The anode electrode sheet includes the novel graphite anode material according to claim 7.

9. The negative electrode sheet according to claim 8, characterized in that, The anode electrode sheet includes a silicon-carbon material formed by compounding the novel graphite anode material with silicon, or a sulfur-carbon material formed by compounding the novel graphite anode material with sulfur.

10. A secondary battery, characterized in that, The secondary battery includes the anode electrode sheet according to claim 8.

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