Lithium ion battery negative electrode and preparation method thereof, lithium ion battery

Abstract

The application discloses a lithium ion battery negative electrode and a preparation method thereof, and a lithium ion battery. The lithium ion battery negative electrode comprises a copper foil base layer, the copper foil base layer comprises a central region and an epitaxial region located at the periphery of the central region, the surface of the copper foil base layer in the central region is coated with a carbon material, and the surface of the copper foil base layer in the epitaxial region is coated with a lithiumophilic material. The lithium ion battery negative electrode can inhibit the growth of lithium dendrites, effectively improve the charging lithium precipitation problem, and improve the safety and capacity attenuation problems of the lithium ion battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a lithium-ion battery negative electrode and its preparation method, as well as a lithium-ion battery. Background Technology

[0002] Currently, lithium-ion batteries are a type of "rocking chair battery," typically employing a charging-then-discharging working mode. During charging, lithium ions are inserted from the positive electrode into the negative electrode, and during discharging, lithium ions are inserted from the negative electrode into the positive electrode. Due to its numerous advantages, it is widely used as a mobile phone battery.

[0003] Lithium-ion batteries typically use lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate as positive electrodes, while carbon materials are commonly used as negative electrodes. During charging, carbon-based negative electrodes are prone to surface lithium deposition. Surface lithium deposition on carbon materials essentially falls into three categories: excessive surface embedding due to insufficient lithium ion insertion; insufficient insertion time for lithium ions under high current density; and failure to insert lithium ions due to overcharging. The deposited dendrites continue to grow, and if they puncture the separator, they can cause a short circuit and safety issues. If they evolve into "dead lithium," the battery's coulombic efficiency will decrease.

[0004] Because lithium ions extracted from the positive electrode during charging do not migrate entirely perpendicular to the electrode in the electrolyte, existing technologies typically over-design the negative electrode, leaving an extra overhang region at the edge of the carbon material for lithium ion intercalation, thus preventing the formation of dendritic lithium deposits on the surface. However, the overhang region of the negative electrode carbon material lacks an opposing positive electrode active material, resulting in a relatively longer lithium ion migration path during charging. This increased impedance is accompanied by insufficient lithium intercalation at the bottom layer and excessive lithium intercalation at the surface layer of the overhang region. During repeated cycles, the overhang region is more prone to surface lithium deposition compared to other regions. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a lithium-ion battery anode and its preparation method, as well as a lithium-ion battery. This, to a certain extent, solves the problem of surface lithium deposition in existing lithium-ion battery anodes, which reduces the cycle stability and safety of lithium-ion batteries.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In one aspect, this application provides a lithium-ion battery negative electrode, which includes a copper foil substrate;

[0008] The copper foil substrate includes a central region and an outer region, wherein the outer region is located around the central region;

[0009] The copper foil substrate surface in the central region is coated with carbon material;

[0010] The surface of the copper foil base layer of the epitaxial region is coated with a lithium-philic material.

[0011] Preferably, the lithium-philic material is one of a lithium-philic graphite mixed material, a lithium-philic graphite composite material, and a lithium-philic graphite double-layer material.

[0012] Preferably, the carbon material is one of a carbon nanotube, a carbon fiber, acetylene black, conductive graphite, and conductive carbon black.

[0013] Preferably, the lithium-philic graphite mixed material is prepared by physically mixing a first lithium-philic substance with graphite; the lithium-philic graphite composite material is prepared by in-situ polymerization of a second lithium-philic substance monomer on the surface of graphite to produce the second lithium-philic substance, and coating the graphite in the second lithium-philic substance; and the lithium-philic graphite double-layer material is prepared by double-layer coating of the first lithium-philic substance and graphite.

[0014] Preferably, the first lithium-philic substance is one of a nitrogen-containing compound, an oxygen-containing compound, a sulfur-containing compound, a phosphorus-containing compound, and a fluorine-containing compound.

[0015] Preferably, the first lithium-philic substance is one of a nitrogen-containing aromatic compound, an oxygen-containing aromatic compound, a sulfur-containing aromatic compound, a phosphorus-containing aromatic compound, and a fluorine-containing aromatic compound.

[0016] Preferably, the second lithium-philic substance monomer is one of a nitrogen-containing polymer monomer, an oxygen-containing polymer monomer, and a sulfur-containing polymer monomer.

[0017] Preferably, the second lithium-philic substance monomer is one of aniline, pyrrole, thiophene, furan, indole, and carbazole.

[0018] Preferably, the second lithium-philic substance is one of a nitrogen-containing polymer, an oxygen-containing polymer, and a sulfur-containing polymer.

[0019] Preferably, the second lithium-philic substance is one of polyaniline, polypyrrole, polythiophene, polyfuran, polyindole, and polycarbazole.

[0020] It should be noted that the second lithium-philic substance monomer corresponds to the second lithium-philic substance, and the second lithium-philic substance monomer produces the second lithium-philic substance through a polymerization reaction, for example, aniline produces polyaniline through a polymerization reaction.

[0021] In a second aspect, the present application provides a preparation method of a lithium ion battery negative electrode, the preparation method of the lithium ion battery negative electrode comprising the following steps:

[0022] A copper foil base layer is provided, the copper foil base layer comprising a central region and an epitaxial region, the epitaxial region being located at the periphery of the central region.

[0023] coating a carbon material on the surface of the copper foil base layer located in the central region;

[0024] coating a lithiumophilic material on the surface of the copper foil base layer located in the epitaxial region;

[0025] The lithiumophilic material is one of a lithiumophilic graphite mixed material, a lithiumophilic graphite composite material, and a lithiumophilic graphite double-layer material.

[0026] Preferably, the preparation method of the lithiumophilic graphite mixed material comprises: adding a first lithiumophilic substance and graphite into water in a mass ratio of X:(1-X), uniformly dispersing to obtain a mixed slurry, and drying the mixed slurry in an oven to obtain the lithiumophilic graphite mixed material, wherein 0X<1.

[0027] Preferably, the preparation method of the lithiumophilic graphite composite material comprises: adding graphite into an ethanol aqueous solution at a temperature T1, dispersing for a time t1, then adding the graphite-containing ethanol aqueous solution into a water solution containing monomers of a second lithiumophilic substance, and dispersing for a time t2 to obtain an ethanol aqueous solution containing monomers of the second lithiumophilic substance and graphite; gradually adding an initiator solution containing a protonic acid into the ethanol aqueous solution containing monomers of the second lithiumophilic substance and graphite at the temperature T1, maintaining the temperature T1 for a time t3 to generate the second lithiumophilic substance, and the second lithiumophilic substance coating the graphite to obtain a reaction product; washing the reaction product with deionized water and anhydrous ethanol; and finally drying the washed reaction product at a temperature T2 to obtain the lithiumophilic graphite composite material.

[0028] The ethanol aqueous solution can be prepared by mixing deionized water and anhydrous ethanol.

[0029] The protonic acid refers to a protonic acid that can dope the second lithiumophilic substance, including but not limited to one or more of hydrochloric acid, sulfuric acid, hypochlorous acid, citric acid, oxalic acid, tartaric acid, a hydrochloric acid derivative, a sulfuric acid derivative, a hypochlorous acid derivative, a citric acid derivative, an oxalic acid derivative, and a tartaric acid derivative.

[0030] The initiator refers to an oxidizing agent that can initiate polymerization of monomers of the second lithiumophilic substance to generate the second lithiumophilic substance; and the initiator includes but is not limited to one of ammonium persulfate, potassium dichromate, potassium iodide, an ammonium sulfate derivative, a potassium dichromate derivative, and a potassium iodide derivative.

[0031] Preferably, the t1 is 1 min-2 h.

[0032] Preferably, the t2 is 1 min-2 h.

[0033] Preferably, the t3 is 30 min-6 h.

[0034] Preferably, the T1 is 0℃-60℃.

[0035] Preferably, the T2 is 25℃-180℃; more preferably, the T2 is 45℃-180℃.

[0036] Preferably, the preparation method of the lithium-philic graphite double-layer material comprises one of the following manners:

[0037] Manner one: first coating a layer of the first lithium-philic substance, and then coating a layer of graphite after drying;

[0038] Manner two: first coating a layer of graphite, and then coating a layer of the first lithium-philic substance after drying.

[0039] In a third aspect, the present application provides a lithium ion battery, which comprises the lithium ion battery negative electrode provided by the present application.

[0040] The technical scheme provided by the present application has the following beneficial effects: in the lithium ion battery negative electrode provided by the present application, the copper foil base layer comprises a central region and an extension region located around the central region; a special coating method is adopted to coat the carbon material on the surface of the copper foil base layer in the central region, and coat the lithium-philic material with strong lithium-philicity on the surface of the copper foil base layer in the extension region. The lithium-philic material has strong attraction to lithium ions. By introducing the lithium-philic material into the lithium ion battery and combining it with the carbon material to build lithium-philic sites, the diffusion of lithium ions from the central region to the extension region is reduced, which helps the uniform dispersion and deposition of lithium ions, thereby inhibiting the growth of lithium dendrites and effectively improving the charging lithium precipitation problem. Moreover, the lithium-philic material provided by the present application is a material combined with lithium-philic substance and graphite, which is used in the negative electrode of the lithium ion battery, can build lithium-philic sites, reduce lithium ion transmission resistance, inhibit the precipitation of surface metal lithium, and effectively improve the battery safety and capacity decay problem.

[0041] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0042] The drawings incorporated into the specification and constituting a part of the present application illustrate the embodiments consistent with the present application, and together with the specification, serve to explain the technical scheme of the present application.

[0043] Figure 1 The schematic diagram of the extension region and the central region in the copper foil base layer provided by an embodiment of the present application is shown.

[0044] Explanation of reference signs:

[0045] 1-extension region; 2-central region. DETAILED DESCRIPTION

[0046] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in any manner without conflict.

[0047] The following are several preferred examples listed in the present application for explaining the technical solutions of the present application.

[0048] Preferred Example One

[0049] A preparation method of a lithium ion battery negative electrode, comprising the following steps:

[0050] As shown in Figure 1 , a copper foil base layer is provided, the copper foil base layer comprises a central region 2 and an epitaxial region 1, the epitaxial region 1 is located at the periphery of the central region 2;

[0051] A carbon material is coated on the surface of the copper foil base layer located in the central region 2;

[0052] A lithiumophilic graphite mixed material is coated on the surface of the copper foil base layer located in the epitaxial region 1;

[0053] The preparation method of the lithiumophilic graphite mixed material comprises: adding a first lithiumophilic substance and graphite into water in a mass ratio of X:(1-X), uniformly dispersing by ultrasonic or stirring to obtain a mixed slurry, and drying the mixed slurry in an oven to obtain the lithiumophilic graphite mixed material, wherein 0X<1;

[0054] The carbon material is one of carbon nanotubes, carbon fibers, acetylene black, conductive graphite and conductive carbon black; the first lithiumophilic substance is one of nitrogen-containing aromatic compounds, oxygen-containing aromatic compounds, sulfur-containing aromatic compounds, phosphorus-containing aromatic compounds and fluorine-containing aromatic compounds.

[0055] The first lithiumophilic substance and the graphite negative electrode are physically mixed, which effectively improves the lithium ion affinity of the graphite negative electrode, makes the lithium ion insertion easier, and thus reduces the probability of precipitation of metallic lithium.

[0056] Preferred Example Two

[0057] A preparation method of a lithium ion battery negative electrode, comprising the following steps:

[0058] As shown in Figure 1As shown, a copper foil base layer is provided, which includes a central region 2 and an epitaxial region 1 located at the periphery of the central region 2;

[0059] A carbon material is coated on the surface of the copper foil base layer located in the central region 2;

[0060] A lithiumophilic graphite composite material is coated on the surface of the copper foil base layer located in the epitaxial region 1;

[0061] The preparation method of the lithiumophilic graphite composite material includes: at 0-60℃, adding graphite into an ethanol aqueous solution, dispersing for 1min-2h by ultrasonic or stirring, then adding the ethanol aqueous solution containing graphite into an aqueous solution containing monomers of a second lithiumophilic substance, dispersing for 1min-2h to obtain an ethanol aqueous solution containing monomers of the second lithiumophilic substance and graphite; at 0-60℃, gradually adding an initiator solution containing a protonic acid into the ethanol aqueous solution containing monomers of the second lithiumophilic substance and graphite, keeping at 0-60℃ for 30min-6h to generate the second lithiumophilic substance, and the second lithiumophilic substance coats the graphite to obtain a reaction product; washing the reaction product by centrifugation or filtration with deionized water and anhydrous ethanol; finally, drying the washed reaction product at 25-180℃ to obtain the lithiumophilic graphite composite material;

[0062] The carbon material is one of carbon nanotubes, carbon fibers, acetylene black, conductive graphite and conductive carbon black; the monomers of the second lithiumophilic substance are one of monomers of nitrogen-containing polymers, monomers of oxygen-containing polymers and monomers of sulfur-containing polymers; the second lithiumophilic substance is one of nitrogen-containing polymers, oxygen-containing polymers and sulfur-containing polymers; the protonic acid is one or more of hydrochloric acid, sulfuric acid, hypochlorous acid, citric acid, oxalic acid, tartaric acid, hydrochloric acid derivatives, sulfuric acid derivatives, hypochlorous acid derivatives, citric acid derivatives, oxalic acid derivatives and tartaric acid derivatives; and the initiator is one of ammonium persulfate, potassium dichromate, potassium iodide, ammonium sulfate derivatives, potassium dichromate derivatives and potassium iodide derivatives.

[0063] The second lithiumophilic substance with strong attraction to lithium ions is polymerized in situ on the surface of the graphite particles, which is beneficial to the migration of lithium ions to the deep layer of the graphite, thereby avoiding excessive or insufficient embedding of lithium ions on the surface layer. In the case that the negative electrode is fully embedded with lithium, the strong attraction of the surface substance of the graphite can construct uniform lithium nucleation sites, so that the lithium is uniformly round in shape, and the growth of lithium dendrites on the surface of the negative electrode is inhibited.

[0064] Preferred Example Three

[0065] A preparation method of a lithium ion battery negative electrode, comprising the following steps:

[0066] As Figure 1As shown, a copper foil base layer is provided, which includes a central region 2 and an epitaxial region 1 located at the periphery of the central region 2;

[0067] A carbon material is coated on the surface of the copper foil base layer located in the central region 2;

[0068] A lithium-philic graphite double-layer material is coated on the surface of the copper foil base layer located in the epitaxial region 1;

[0069] The preparation method of the lithium-philic graphite double-layer material includes one of the following ways:

[0070] Way one: first coat a layer of first lithium-philic substance, and then coat a layer of graphite after drying;

[0071] Way two: first coat a layer of graphite, and then coat a layer of first lithium-philic substance after drying;

[0072] The carbon material is one of carbon nanotubes, carbon fibers, acetylene black, conductive graphite, and conductive carbon black; and the first lithium-philic substance is one of nitrogen-containing aromatic compounds, oxygen-containing aromatic compounds, sulfur-containing aromatic compounds, phosphorus-containing aromatic compounds, and fluorine-containing aromatic compounds.

[0073] In order to more clearly explain the technical solutions of the present application, the following embodiments are further listed.

[0074] Embodiment 1

[0075] The preparation method of the lithium ion battery negative electrode of the present embodiment includes the following steps:

[0076] A copper foil base layer is provided, which includes a central region and an epitaxial region located at the periphery of the central region;

[0077] Conductive graphite is coated on the surface of the copper foil base layer located in the central region;

[0078] A lithium-philic graphite mixed material is coated on the surface of the copper foil base layer located in the epitaxial region;

[0079] The preparation method of the lithium-philic graphite mixed material includes: adding nitrogen-containing aromatic compounds and graphite in a mass ratio of 0.5:0.5 into water, uniformly dispersing by ultrasonic or stirring to obtain a mixed slurry, and placing the mixed slurry in an oven for drying to obtain the lithium-philic graphite mixed material.

[0080] Embodiments 2-4

[0081] The lithium ion battery negative electrodes of embodiments 2-4 are prepared by referring to the preparation method of embodiment 1, except that the carbon material, the first lithium-philic substance, and the mass ratio of the first lithium-philic substance and the graphite are different, and the different raw materials and different masses are shown in Table 1.

[0082] Table 1

[0083]

[0084] Example 5

[0085] The preparation method of the lithium ion battery negative electrode of the present embodiment comprises the following steps:

[0086] A copper foil base layer is provided, which comprises a central region and an extension region, and the extension region is located at the periphery of the central region;

[0087] A carbon nanotube is coated on the surface of the copper foil base layer located in the central region;

[0088] A lithiumophilic graphite composite material is coated on the surface of the copper foil base layer located in the extension region;

[0089] The preparation method of the lithiumophilic graphite composite material comprises: at 30°C, graphite is added to an ethanol aqueous solution, and after being dispersed for 1 h by ultrasonic or stirring, the ethanol aqueous solution containing the graphite is added to an aniline-containing aqueous solution, and dispersed for 1.5 h to obtain an aniline and graphite ethanol aqueous solution; at 30°C, ammonium persulfate solution containing hydrochloric acid is gradually added to the aniline and graphite ethanol aqueous solution, and the reaction is maintained at 30°C for 2 h to generate polyaniline, and the polyaniline coats the graphite to obtain a reaction product; the reaction product is washed by centrifugation with deionized water and anhydrous ethanol; finally, the washed reaction product is dried at 100°C to obtain the lithiumophilic graphite composite material.

[0090] Examples 6-9

[0091] The lithium ion battery negative electrodes of Examples 6-9 are prepared according to the preparation method of Example 5, except that the time t1, the time t2, the time t3, the temperature T1, the temperature T2, the carbon material, and the second lithiumophilic material are different, and the different raw materials and different parameters are shown in Table 2.

[0092] Table 2

[0093]

[0094] Example 10

[0095] The preparation method of the lithium ion battery negative electrode of the present embodiment comprises the following steps:

[0096] A copper foil base layer is provided, which comprises a central region and an extension region, and the extension region is located at the periphery of the central region;

[0097] A conductive graphite is coated on the surface of the copper foil base layer located in the central region;

[0098] A first lithiumophilic substance is first coated on the surface of the copper foil base layer located in the extension region, and after drying, a layer of graphite is coated.

[0099] Embodiment 11

[0100] The preparation method of the lithium ion battery negative electrode of the present embodiment comprises the following steps:

[0101] A copper foil base layer is provided, which comprises a central region and an epitaxial region, and the epitaxial region is located at the periphery of the central region;

[0102] The surface of the copper foil base layer located in the central region is coated with conductive carbon black;

[0103] The surface of the copper foil base layer located in the epitaxial region is first coated with a layer of graphite, and then a layer of first lithiumophilic substance is coated after drying.

[0104] In summary, the present application adopts a special coating method, in which carbon material is coated on the surface of the copper foil base layer in the central region, and lithiumophilic material with strong lithium affinity is coated on the surface of the copper foil base layer in the epitaxial region. The lithiumophilic material has strong attraction to lithium ions, and the introduction of the lithiumophilic material into the lithium ion battery in combination with the carbon material to construct lithiumophilic sites reduces the diffusion of lithium ions from the central region to the epitaxial region, which helps the uniform dispersion and deposition of lithium ions, thereby inhibiting the growth of lithium dendrites and effectively improving the charging lithium precipitation problem. Moreover, the lithiumophilic material of the present application is a material combined with lithiumophilic substance and graphite, which is used in the negative electrode of the lithium ion battery to construct lithiumophilic sites, reduce lithium ion transmission resistance, inhibit the precipitation of surface metal lithium, and effectively improve the battery safety and capacity decay problem.

[0105] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A lithium-ion battery anode, characterized by, The copper foil substrate includes a central region and an extension region located at the periphery of the central region. The copper foil substrate surface of the central region is coated with a carbon material. The copper foil substrate surface of the extension region is coated with a lithiumophilic material. The carbon material is one of carbon nanotubes, carbon fibers, acetylene black, conductive graphite, and conductive carbon black.

2. The lithium-ion battery anode of claim 1, wherein, The lithiumophilic material is one of a lithiumophilic graphite mixed material, a lithiumophilic graphite composite material, and a lithiumophilic graphite double-layer material.

3. The lithium-ion battery anode of claim 1, wherein, The lithiumophilic graphite mixed material is prepared by physically mixing a first lithiumophilic substance with graphite; the lithiumophilic graphite composite material is prepared by in-situ polymerization of a second lithiumophilic substance monomer on the surface of graphite to produce the second lithiumophilic substance while coating the graphite in the second lithiumophilic substance; and the lithiumophilic graphite double-layer material is prepared by double-layer coating of a first lithiumophilic substance and graphite. The first lithiumophilic substance is one of a nitrogen-containing compound, an oxygen-containing compound, a sulfur-containing compound, a phosphorus-containing compound, and a fluorine-containing compound.

4. The lithium-ion battery anode of claim 3, wherein, The first lithiumophilic substance is one of a nitrogen-containing aromatic compound, an oxygen-containing aromatic compound, a sulfur-containing aromatic compound, a phosphorus-containing aromatic compound, and a fluorine-containing aromatic compound.

5. The lithium-ion battery anode of claim 3, wherein, The second lithiumophilic substance monomer is one of a nitrogen-containing polymer monomer, an oxygen-containing polymer monomer, and a sulfur-containing polymer monomer; and the second lithiumophilic substance is one of a nitrogen-containing polymer, an oxygen-containing polymer, and a sulfur-containing polymer corresponding to the second lithiumophilic substance monomer.

6. The lithium-ion battery anode of claim 3, wherein, The second lithiumophilic substance monomer is one of aniline, pyrrole, thiophene, furan, and indole; and the second lithiumophilic substance is one of polyaniline, polypyrrole, polythiophene, polyfuran, and polyindole corresponding to the second lithiumophilic substance monomer.

7. The lithium-ion battery anode of claim 3, wherein, The method includes the following steps:

8. A method of producing a lithium-ion battery negative electrode, characterized by, providing a copper foil substrate including a central region and an extension region located at the periphery of the central region; coating a carbon material on the surface of the copper foil substrate located at the central region; coating a lithiumophilic material on the surface of the copper foil substrate located at the extension region; The lithiumophilic material is one of a lithiumophilic graphite mixed material, a lithiumophilic graphite composite material, and a lithiumophilic graphite double-layer material. The lithiumophilic graphite mixed material is prepared by physically mixing a first lithiumophilic substance with graphite; the lithiumophilic graphite composite material is prepared by in-situ polymerization of a second lithiumophilic substance monomer on the surface of graphite to produce the second lithiumophilic substance while coating the graphite in the second lithiumophilic substance; and the lithiumophilic graphite double-layer material is prepared by double-layer coating of a first lithiumophilic substance and graphite. The preparation method of the lithiumophilic graphite mixed material includes: adding a first lithiumophilic substance and graphite in a mass ratio of X:(1-X) into water, uniformly dispersing to obtain a mixed slurry, and drying the mixed slurry in an oven to obtain the lithiumophilic graphite mixed material, wherein 0X<1.

9. The method for preparing a lithium-ion battery negative electrode according to claim 8, characterized in that, ​ 10. The method for preparing a lithium-ion battery negative electrode according to claim 8, characterized in that, The preparation method of the lithium-philic graphite composite material comprises the following steps: adding graphite into an ethanol aqueous solution at a temperature T1, dispersing for a time t1, then adding the graphite-containing ethanol aqueous solution into a water solution containing monomers of a second lithium-philic substance, and dispersing for a time t2 to obtain an ethanol aqueous solution containing monomers of the second lithium-philic substance and graphite; gradually adding an initiator solution containing a protonic acid into the ethanol aqueous solution containing monomers of the second lithium-philic substance and graphite at the temperature T1, keeping the temperature T1 for a time t3 to generate the second lithium-philic substance, and the second lithium-philic substance coating the graphite to obtain a reaction product; cleaning the reaction product with deionized water and anhydrous ethanol; and finally drying the cleaned reaction product at a temperature T2 to obtain the lithium-philic graphite composite material.

11. The method for preparing a lithium-ion battery negative electrode according to claim 10, characterized in that, The protonic acid is one or more of hydrochloric acid, sulfuric acid, hypochlorous acid, citric acid, oxalic acid, tartaric acid, a hydrochloric acid derivative, a sulfuric acid derivative, a hypochlorous acid derivative, a citric acid derivative, an oxalic acid derivative, a tartaric acid derivative.

12. The method for preparing a lithium-ion battery negative electrode according to claim 10, characterized in that, The initiator is one of ammonium persulfate, potassium dichromate, potassium iodide, an ammonium sulfate derivative, a potassium dichromate derivative, a potassium iodide derivative.

13. The method for preparing a lithium-ion battery negative electrode according to claim 10, characterized in that, The t1 is 1 min to 2 h; the t2 is 1 min to 2 h; the t3 is 30 min to 6 h; the T1 is 0℃ to 60℃; and the T2 is 25℃ to 180℃.

14. The method for preparing a lithium-ion battery negative electrode according to claim 8, characterized in that, The preparation method of the lithium-philic graphite double-layer material comprises one of the following modes: Mode one: coating a first lithium-philic substance first, and then coating graphite after drying; Mode two: coating graphite first, and then coating a first lithium-philic substance after drying.

15. A lithium-ion battery, characterized by, The lithium ion battery negative electrode comprises the lithium-philic graphite composite material.

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