A high-rate lithium-ion battery negative electrode material and preparation method thereof

Abstract

The present invention provides a high-rate negative electrode material for lithium-ion batteries and a method for preparing the same. The method comprises: (1) adding an inorganic lithium salt, a nitric acid compound, an organic nitrogen compound, and an additive to water and mixing to obtain a solution A; (2) preparing a porous graphite composite material B doped with a rare earth compound; (3) adding the porous graphite composite material B to the solution A and adding a graphene oxide solution, mixing, filtering, washing, and vacuum drying to obtain an inorganic lithium salt-coated graphite composite; and (4) using an electrochemical deposition method to scan the inorganic lithium salt-coated graphite composite as a working electrode, washing, drying, high-temperature sintering, and pulverizing to obtain the lithium-ion battery negative electrode material. The technical solution of the present invention can improve the initial efficiency and the fast-charging capability of graphite, while also taking into account energy density and high-temperature performance.

Description

Technical Field

[0001] The present invention belongs to the field of lithium ion battery material preparation, and in particular relates to a high-rate lithium ion battery negative electrode material and a preparation method thereof. Background Art

[0002] Currently, the negative electrode materials on the market are mainly artificial graphite, which mainly reduces the impedance by reducing the aggregate particle size and coating it with amorphous carbon. However, since reducing the aggregate particle size or increasing the carbon coating amount will reduce the energy density, it is very necessary to select the appropriate aggregate particle size or control the coating amount of the material. At present, the main measures to improve the fast charging performance of materials are to coat the surface of the graphite core with materials with low electronic or ionic impedance, and improve the interface impedance between the core and the shell, thereby increasing the diffusion rate of the material and its electronic conduction rate.

[0003] At present, the commercialized artificial graphite is mainly coated with amorphous carbon on the outer layer, but it can only meet the requirements of ≤4C charging capacity, specific capacity ≤350mAh / g, and compaction density ≤1.6g / cm 3 The requirements of the battery are met, and the preparation method is generally solid phase or liquid phase method with poor consistency, which makes the charging capacity and energy density of the material unable to meet future needs.

[0004] In view of this, the present invention proposes a high-rate lithium-ion battery negative electrode material and a preparation method thereof, in which a new material is coated on the surface of the material to improve the power performance and energy density of the material. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a high-rate negative electrode material for lithium-ion batteries, wherein a block-shaped inorganic lithium salt-coated graphite complex is prepared by a hydrothermal method, and lithium salt is deposited on its surface by an electrochemical precipitation method to improve the initial efficiency; a graphite composite material is prepared, which can improve the fast charging capability of graphite while taking into account the energy density and its high-temperature performance.

[0006] In order to achieve the above objectives, the technical solutions adopted are:

[0007] A method for preparing a high-rate lithium-ion battery negative electrode material comprises the following steps:

[0008] (1) Adding an inorganic lithium salt, a nitric acid compound, an organic nitrogen compound, and an additive to water and mixing them uniformly to obtain solution A;

[0009] (2) preparing a porous graphite composite material B doped with a rare earth compound;

[0010] (3) adding the porous graphite composite material B to the solution A, mixing, adding the graphene oxide solution, mixing, reacting at 100-200° C. for 1-6 hours, filtering, washing, and vacuum drying to obtain a block-shaped inorganic lithium salt-coated graphite composite;

[0011] (4) An electrochemical deposition method is adopted, with the inorganic lithium salt-coated graphite composite as the working electrode, saturated calomel as the counter electrode, and 0.1 mol / L lithium difluoroborate dimethyl carbonate (DMC) solution as the solvent, scanning at -2V to 2V, 0.5 to 5mV / s for 10 to 100 cycles, washing with dilute hydrochloric acid, drying, sintering at a high temperature of 800 to 1200°C for 1 to 6 hours, and crushing to obtain the lithium ion battery negative electrode material.

[0012] Furthermore, in the step (1), the mass ratio of the inorganic lithium salt, the nitric acid compound, the organic nitrogen compound and the additive is 100:80-100:1-10:1-10

[0013] The mass ratio of solute (inorganic lithium salt, nitric acid compound, organic nitrogen compound and additive) to water in solution A is 1 to 10:100.

[0014] Furthermore, in the step (1), the inorganic lithium salt is one of LiCO3, LiOH, LiNO3, LiCl, LiBr, LiI, Li2S, LiF, Li2SO4, Li2SO3, LiClO4, LiMnO4, LiO2, and Li2S2O3;

[0015] The nitric acid compound is one of magnesium nitrate, calcium nitrate, potassium nitrate and ferric nitrate;

[0016] The organic nitrogen compound is one of dimethylamine, dipropylamine, tripropylamine, n-butylamine, diethylamine, ethanolamine, and triethylamine;

[0017] The additive is one of Li2B4O7, Li3PO3, and Li3NbO3.

[0018] Furthermore, in the step (2), the step of preparing the porous graphite composite material B doped with rare earth compounds is as follows: after dissolving melamine, ammonium hydrogen phosphate, and rare earth chloride in water, adding graphite and mixing evenly, heating and stirring until it becomes a gel, vacuum drying, calcining, and washing to obtain the porous graphite composite material B doped with rare earth compounds.

[0019] Furthermore, the rare earth chloride is one of cerium chloride, lanthanum chloride, europium chloride, neodymium chloride or yttrium chloride.

[0020] Furthermore, the mass ratio of melamine, ammonium hydrogen phosphate, rare earth chloride and graphite is 0.5-2:1-5:1-5:100.

[0021] Furthermore, in the step (2), stirring at 50-120° C. until the mixture becomes gel-like;

[0022] Calcinate at 200-400°C for 1-6 hours under an inert atmosphere;

[0023] Wash with dilute hydrochloric acid and deionized water.

[0024] Furthermore, in the step (3), the concentration of graphene oxide is 0.5 to 5 wt%.

[0025] Furthermore, in the step (3), the mass ratio of solution A, porous graphite composite material B and graphene oxide is 100:100 to 200:1 to 5.

[0026] Another object of the present invention is to provide a high-rate lithium-ion battery negative electrode material, which is prepared using the above-mentioned preparation method and has advantages in energy density, high-temperature performance, low-temperature performance, etc.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention deposits inorganic lithium salts on the graphite surface by chemical methods, thereby reducing the irreversible capacity loss during the charge and discharge process of the material and improving the initial efficiency. At the same time, relying on the high lithium ion conductivity of the inorganic lithium salt in the coating layer, the transmission rate of lithium ions during the charge and discharge process of the negative electrode material is increased, and the rate performance is improved.

[0029] 2. The present invention improves the electronic conductivity of the core graphite by doping rare earth compounds into the core. At the same time, after melamine carbon is sintered at a high temperature of 800-1200°C, amorphous carbon containing nitrogen is obtained, and the combination of nitrogen atoms and carbon atoms has higher electronic conductivity, thereby improving the electronic conductivity of the composite material. The nano-micrometer pores left after the carbonization of ammonium hydrogen phosphate improve the material's liquid retention capacity, and phosphorus itself has a high specific capacity, thereby further improving the material's energy density.

[0030] 3. The present invention deposits organic lithium salts on its outer layer through electrochemical deposition, thereby improving the compatibility of the material with the electrolyte and improving the low-temperature performance. It also interacts with the inorganic lithium salts on the surface of the inner core graphite and the organic lithium salts in the outer shell to play a synergistic role and improve the high-temperature and low-temperature performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the SEM image of the graphite composite material prepared in Example 2. DETAILED DESCRIPTION

[0032] To further illustrate the high-rate lithium-ion battery negative electrode material and its preparation method according to the present invention and achieve the intended purpose of the invention, the following, in conjunction with preferred embodiments, describes in detail the specific implementation, structure, features, and efficacy of the high-rate lithium-ion battery negative electrode material and its preparation method according to the present invention. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable form.

[0033] The following is a detailed description of a high-rate lithium-ion battery negative electrode material and a preparation method thereof according to the present invention, with reference to specific embodiments:

[0034] Example 1.

[0035] The specific steps are as follows:

[0036] (1) Inorganic lithium salt, nitric acid compound, organic nitrogen compound and additive are weighed in a mass ratio of 100:80 to 100:1 to 10:1 to 10, and added to deionized water to prepare solution A.

[0037] Wherein, the inorganic lithium salt is one of LiCO3, LiOH, LiNO3, LiCl, LiBr, LiI, Li2S, LiF, Li2SO4, Li2SO3, LiClO4, LiMnO4, LiO2, and Li2S2O3;

[0038] The nitric acid compound is one of magnesium nitrate, calcium nitrate, potassium nitrate and ferric nitrate;

[0039] The organic nitrogen compound is one of dimethylamine, dipropylamine, tripropylamine, n-butylamine, diethylamine, ethanolamine, and triethylamine;

[0040] The additive is one of Li2B4O7, Li3PO3, and Li3NbO3.

[0041] The mass ratio of solute to solvent in solution A is 1 to 10:100.

[0042] (2) Melamine, ammonium hydrogen phosphate, and rare earth chloride were dissolved in deionized water, ultrasonically treated for 30 minutes, and then artificial graphite was added and mixed evenly. The mixture was heated and stirred at 50-120° C. until it became a gel, vacuum dried, and then calcined at 200-400° C. under an inert atmosphere for 1-6 hours. The mixture was washed with dilute hydrochloric acid and deionized water 10 times respectively to obtain a porous graphite composite material B.

[0043] Wherein, the rare earth chloride is one of cerium chloride, lanthanum chloride, europium chloride, neodymium chloride or yttrium chloride.

[0044] The mass ratio of melamine, ammonium hydrogen phosphate, rare earth chloride and graphite is 0.5-2:1-5:1-5:100.

[0045] (3) The porous graphite composite material B is added to the solution A and mixed evenly, and 0.5 to 5 wt% of the graphene oxide solution is added. After mixing evenly, the mixture is transferred to a high-pressure reactor and hydrothermally reacted at 100 to 200° C. for 1 to 6 hours. The mixture is then filtered, washed, and vacuum-dried to obtain a block-shaped inorganic lithium salt-coated graphite composite.

[0046] The mass ratio of solution A, porous graphite composite material B and graphene is 100:100-200:1-5.

[0047] (4) Using electrochemical deposition method, with inorganic lithium salt coated graphite composite as working electrode, saturated calomel as counter electrode, 0.1 mol / L lithium difluoroborate DMC solution as solvent, cyclic voltammetry, scanning at -2V~2V, 0.5~5mV / s for 10~100 cycles, washing with dilute hydrochloric acid, drying, and then sintering at high temperature of 800~1200℃ for 1~6h, crushing to obtain graphite composite material.

[0048] The present invention achieves uniform and dense coating of the graphite surface with lithium salt compounds with high lithium ion conductivity through the process of chemical deposition of inorganic lithium salts on the graphite surface and electrochemical deposition of lithium salts, thereby improving the insertion and extraction rate of lithium ions and their initial efficiency during the charge and discharge process. At the same time, rare earth compounds are doped on the surface to enhance the structural stability of the material and improve the cycle performance.

[0049] Example 2.

[0050] The specific steps are as follows:

[0051] (1) Weigh 100 g of lithium carbonate, 90 g of magnesium nitrate, 5 g of dimethylamine, and 5 g of Li2B4O7, and add them to 4000 ml of deionized water to prepare solution A.

[0052] (2) 1 g of melamine, 3 g of ammonium hydrogen phosphate, and 3 g of cerium chloride were dissolved in 500 ml of deionized water and ultrasonically treated for 30 min. Then, 100 g of artificial graphite was added and mixed evenly. The mixture was heated and stirred at 80 °C until it became a gel. The mixture was then vacuum dried at 80 °C for 24 h, calcined at 300 °C for 3 h under an argon inert atmosphere, and washed 10 times with dilute hydrochloric acid and deionized water, respectively, to obtain a porous graphite composite material B.

[0053] (3) Take 150g of porous graphite composite material B and add it to 100ml of solution A, mix well, add 100g of 2wt% graphene oxide solution, mix well, transfer to a high-pressure reactor, and hydrothermally react at 150°C for 3h, then filter, wash, and vacuum dry at 80°C for 24h to obtain a block-structured inorganic lithium salt-coated graphite composite.

[0054] (4) The electrochemical deposition method was used, with an inorganic lithium salt-coated graphite composite as the working electrode, saturated calomel as the counter electrode, and a 0.1 mol / L lithium difluoroborate dimethyl carbonate (DMC) solution as the solvent. Cyclic voltammetry was performed at -2 V to 2 V, 1 mV / s scanning for 50 cycles, washed 10 times with dilute hydrochloric acid, dried, and then sintered at 900 ° C for 3 h and crushed to obtain a graphite composite material.

[0055] Example 3.

[0056] The specific steps are as follows:

[0057] (1) Weigh 100 g of LiCl, 80 g of calcium nitrate, 1 g of dipropylamine, and 1 g of Li3PO3 and add them to 18200 ml of deionized water to prepare solution A.

[0058] (2) 0.5 g of melamine, 1 g of ammonium hydrogen phosphate, and 1 g of lanthanum chloride were dissolved in 1000 ml of deionized water and ultrasonically treated for 30 min. 100 g of artificial graphite was then added and mixed uniformly. The mixture was heated and stirred at 50°C until it became a gel. The mixture was then vacuum dried at 80°C for 24 h and calcined at 200°C under an argon inert atmosphere for 6 h. The mixture was then washed 10 times with dilute hydrochloric acid and 10 times with deionized water to obtain a porous graphite composite material B.

[0059] (3) 100 g of porous graphite composite material B was added to 200 ml of solution A and mixed evenly. 200 g of 0.5% graphene oxide solution was added and mixed evenly. The mixture was transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 100 ° C for 6 h. The mixture was then filtered, washed, and vacuum-dried at 80 ° C for 24 h to obtain a block-shaped inorganic lithium salt-coated graphite composite.

[0060] (4) The electrochemical deposition method was used, with an inorganic lithium salt-coated graphite composite as the working electrode, saturated calomel as the counter electrode, and a 0.1 mol / L lithium difluoroborate dimethyl carbonate (DMC) solution as the solvent. Cyclic voltammetry was performed, scanning at -2 V to 2 V, 0.5 mV / s for 10 cycles, washing with dilute hydrochloric acid, drying, and then sintering at 800 ° C for 6 h and crushing to obtain a graphite composite material.

[0061] Example 4.

[0062] The specific steps are as follows:

[0063] (1) Weigh 100 g of Li2SO3, 100 g of potassium nitrate, 10 g of tripropylamine and 10 g of Li3NbO3 and add them to 2200 ml of deionized water to obtain solution A.

[0064] (2) 2 g of melamine, 5 g of ammonium hydrogen phosphate, and 5 g of neodymium chloride were dissolved in 1000 ml of deionized water and ultrasonically treated for 30 min. Then, 100 g of artificial graphite was added and mixed evenly. The mixture was heated and stirred at 120 ° C until it became a gel. Then, it was vacuum dried at 80 ° C for 24 h. After that, it was calcined at 400 ° C for 1 h under an argon inert atmosphere. The mixture was washed with dilute hydrochloric acid and deionized water for 10 times respectively to obtain a porous graphite composite material B.

[0065] (3) 100 g of porous graphite composite material B was added to 100 g of solution A and mixed evenly, and 100 g of 5 wt% graphene oxide solution was added and mixed evenly. The mixture was transferred to a high-pressure reactor and hydrothermally reacted at 200 ° C for 1 h. After filtering, washing, and vacuum drying at 80 ° C for 24 h, a block-shaped inorganic lithium salt-coated graphite composite was obtained.

[0066] (4) The electrochemical deposition method was used, with an inorganic lithium salt-coated graphite composite as the working electrode, saturated calomel as the counter electrode, and a 0.1 mol / L lithium difluoroborate dimethyl carbonate (DMC) solution as the solvent. Cyclic voltammetry was performed, scanning at -2 V to 2 V, 5 mV / s for 100 cycles, washing with dilute hydrochloric acid, drying, and then sintering at 1200 ° C for 1 h in an argon atmosphere and crushing to obtain a graphite composite material.

[0067] Comparative Example 1:

[0068] The inorganic lithium salt-coated graphite composite with a block structure prepared in step (3) of Example 2 is crushed to obtain a graphite composite material.

[0069] Comparative Example 2.

[0070] The electrochemical deposition method was adopted, with artificial graphite as the working electrode, saturated calomel as the counter electrode, and 0.1 mol / L lithium difluoroborate dimethyl carbonate (DMC) solution as the solvent. Cyclic voltammetry was performed, scanning at -2V to 2V, 1mV / s for 50 cycles, washing with dilute hydrochloric acid, drying, and then sintering at 900℃ for 3h in an argon atmosphere and crushing to obtain a graphite composite material.

[0071] 1. Physical and chemical properties test

[0072] 1.1 SEM test

[0073] The graphite composite material prepared in Example 2 was subjected to SEM testing, and the test results are as follows: Figure 1 As shown. Figure 1 It can be seen from the graphite composite material obtained in Example 2 that the graphite composite material is in granular form with uniform size distribution, and the particle size is between 10 and 15 μm.

[0074] 1.2 Powder conductivity test:

[0075] The powder was pressed into a block structure, and then the electrical conductivity of the powder was tested using a four-probe tester. The test results are shown in Table 1.

[0076] 1.3 Powder compaction density test

[0077] The graphite composite materials in Examples 2 to 4 and Comparative Examples 1-2 were subjected to powder compaction density tests. During the test, a certain mass of powder was weighed and placed in a mold, and a 2T pressure was used to press (using a powder compaction density meter, 1g of powder was placed in a fixed kettle and then pressed with a 2T pressure, left to stand for 10S, and then the volume under compression was calculated, and the compaction density was calculated). At the same time, in accordance with GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries", the test results are shown in Table 1.

[0078] Table 1

[0079] project Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Powder resistivity (Ω·m) <![CDATA[8*10 -8 ]]> <![CDATA[5*10 -8 ]]> <![CDATA[6*10 -8 ]]> <![CDATA[8*10 -7 ]]> <![CDATA[7*10 -7 ]]> <![CDATA[Powder tap density (g / cm 3 )]]> 1.69 1.66 1.64 1.51 1.53 <![CDATA[Specific surface area (m 2 / g)]]> 1.82 1.77 1.68 1.21 1.38

[0080] As can be seen from Table 1, the powder resistivity of the artificial graphite composite material prepared by the present invention is significantly lower than that of the comparative example. The reason is that the core and shell of the negative electrode material are doped with inorganic lithium salts, rare earth compounds and organic lithium salts, respectively, to reduce their electronic and ionic resistivities; and the electrochemical deposition method has the characteristic of high density, which improves the powder compaction density.

[0081] 2. Button battery test

[0082] The graphite composite materials from Examples 2-4 and Comparative Examples 1-2 were assembled into button-type batteries A1, A2, A3, B1, and B2, respectively. The assembly method involved adding a binder, a conductive agent, and a solvent to the negative electrode material, stirring to form a slurry, coating the mixture on copper foil, and drying and rolling to produce the negative electrode sheet. The binder used was LA132, the conductive agent was SP, the negative electrode materials were the graphite composite materials from Examples 2-4 and Comparative Examples 1-2, and the solvent was double-distilled water. The ratio of the components was: negative electrode material: SP: LA132: double-distilled water = 95g: 1g: 4g: 220mL; the electrolyte was LiPF6 / EC+DEC (LiPF6 concentration was 1.2 mol / L, EC:DEC volume ratio was 1:1), the metal lithium sheet served as the counter electrode, and the separator was a polyethylene (PE), polypropylene (PP), or polyethylene propylene (PEP) composite film. The button cells were assembled in an argon-filled glove box. Electrochemical performance testing was performed on a Wuhan Blue Power CT2001A battery tester with a charge and discharge voltage range of 0.005 V to 2.0 V and a charge and discharge rate of 0.1 C. The test results are shown in Table 2.

[0083] At the same time, take the above-mentioned negative electrode sheet and test its liquid absorption and retention ability.

[0084] Table 2

[0085]

[0086] As can be seen from Table 2, the first discharge capacity and the first charge and discharge efficiency of the lithium-ion battery using the graphite composite negative electrode material obtained in Examples 2 to 4 are significantly higher than those in Comparative Examples 1-2. The reason is that the organic lithium and inorganic lithium salts provide sufficient lithium ions for the first charge and discharge of the battery, thereby improving the specific capacity and conductivity of the material and further improving the first efficiency. At the same time, the graphite composite material has a high specific surface area, which can improve the liquid absorption capacity of the material.

[0087] 3. Soft pack battery test

[0088] The graphite composite materials in Examples 2 to 4 and Comparative Examples 1 to 2 were used as negative electrode materials to prepare negative electrode sheets. 1 / 3 Co 1 / 3 Mn 1 / 3 2Ah soft-pack batteries A10, A20, A30, B10, and B20 were prepared using a LiPF6 solution (EC+DEC, 1:1 volume ratio, 1.3 mol / L LiPF6 concentration) as the positive electrode and a Celebard 2400 separator. The soft-pack batteries were then tested for cycling performance (1C / 1C, 25°C, 2.8-4.2 V) and rate capability.

[0089] Rate performance test conditions: charge rate: 1C / 2C / 3C / 5C, discharge rate 1C; voltage range: 2.8~4.2V.

[0090] The test results are shown in Table 3.

[0091] Table 3

[0092]

[0093] It can be seen from Table 3 that the soft-pack battery prepared from the graphite composite material of the present invention has a better constant current ratio. The reason is that the surface of the material in the embodiment is coated with inorganic lithium, which can provide sufficient lithium ions during the charge and discharge process, thereby improving the fast charging performance of the material, that is, improving the constant current ratio of the material, and improving the cycle performance.

[0094] The above is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the embodiments of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the embodiments of the present invention are still within the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-rate negative electrode material for a lithium-ion battery, characterized in that: The following steps are involved: (1) Adding an inorganic lithium salt, a nitric acid compound, an organic nitrogen compound, and an additive to water and mixing them uniformly to obtain a solution A; (2) preparing a porous graphite composite material B doped with a rare earth compound, comprising the steps of: dissolving melamine, ammonium hydrogen phosphate, and rare earth chloride in water, adding graphite and mixing uniformly, heating and stirring until the mixture is in a gel state, vacuum drying, calcining, and washing to obtain a porous graphite composite material B doped with a rare earth compound; (3) adding the porous graphite composite material B to the solution A, mixing, adding the graphene oxide solution, mixing, reacting at 100-200° C. for 1-6 hours, filtering, washing, and vacuum drying to obtain a block-shaped inorganic lithium salt-coated graphite composite; (4) An electrochemical deposition method is adopted, with the inorganic lithium salt-coated graphite composite as the working electrode, saturated calomel as the counter electrode, and 0.1 mol / L lithium difluoroborate dimethyl carbonate solution as the solvent, scanning at -2V to 2V, 0.5 to 5mV / s for 10 to 100 cycles, washing with dilute hydrochloric acid, drying, sintering at a high temperature of 800 to 1200°C for 1 to 6 hours, and crushing to obtain the lithium ion battery negative electrode material.

2. The preparation method according to claim 1, characterized in that In the step (1), the mass ratio of the inorganic lithium salt, the nitric acid compound, the organic nitrogen compound and the additive is 100:80-100:1-10:1-10; The mass ratio of the inorganic lithium salt, the nitric acid compound, the organic nitrogen compound, the additive and the water in the solution A is 1 to 10:

100.

3. The preparation method according to claim 1, characterized in that In the step (1), the inorganic lithium salt is one of LiCO3, LiOH, LiNO3, LiCl, LiBr, LiI, Li2S, LiF, Li2SO4, Li2SO3, LiClO4, LiMnO4, LiO2, and Li2S2O3; The nitric acid compound is one of magnesium nitrate, calcium nitrate, potassium nitrate and ferric nitrate; The organic nitrogen compound is one of dimethylamine, dipropylamine, tripropylamine, n-butylamine, diethylamine, ethanolamine, and triethylamine; The additive is one of Li2B4O7, Li3PO3, and Li3NbO3.

4. The preparation method according to claim 1, characterized in that The rare earth chloride is one of cerium chloride, lanthanum chloride, europium chloride, neodymium chloride and yttrium chloride.

5. The preparation method according to claim 1, characterized in that The mass ratio of the melamine, ammonium hydrogen phosphate, rare earth chloride and graphite is 0.5-2:1-5:1-5:

100.

6. The preparation method according to claim 4, characterized in that In the step (2), stirring at 50-120° C. until the mixture becomes gel-like; Calcinate in an inert atmosphere at 200-400°C for 1-6 hours; Wash with dilute hydrochloric acid and deionized water.

7. The preparation method according to claim 1, characterized in that In the step (3), the concentration of graphene oxide is 0.5 to 5 wt%.

8. The preparation method according to claim 1, characterized in that In the step (3), the mass ratio of solution A, porous graphite composite material B and graphene oxide is 100:100-200:1-5.

9. A high-rate lithium-ion battery negative electrode material, characterized in that: The lithium-ion battery negative electrode material is prepared by the preparation method according to any one of claims 1 to 8.

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