Lithium battery negative electrode and preparation method therefor, and lithium battery

Abstract

A lithium battery negative electrode, which comprises a silicon-based / graphite composite electrode material and polyanthraquinonylimide lithium. By introducing the polyanthraquinonylimide lithium into the lithium battery negative electrode, additional active lithium ions can be provided for a battery system during cycling, and lithium loss caused by the formation of an SEI film on the surface of the negative electrode can be compensated, such that the initial coulombic efficiency of the battery is improved, and the release of the battery capacity is improved. Moreover, the polyanthraquinonylimide lithium itself has relatively good mechanical properties, solvent resistance, and relatively good elasticity and relatively high tensile strength, and thus can withstand the volume change of silicon-based particles during charge-discharge cycles, and prevent the silicon-based negative electrode from powdering, thereby improving the long cycling performance of the battery. In addition, the carbonyl group in the polyanthraquinonylimide lithium can provide additional capacity for the negative electrode during cycling.

Description

Lithium battery negative electrode and preparation method thereof, lithium battery Technical Field

[0001] The present application relates to lithium batteries, and in particular to silicon-based negative electrode technology. Background Art

[0002] In recent years, with the booming development of the electric vehicle market, higher requirements have been placed on the endurance of electric vehicles. Among various new battery systems, solid-state lithium batteries use solid electrolytes instead of organic electrolytes, which is expected to break through the technical bottleneck of liquid lithium batteries and achieve higher energy density. The realization of high energy density of solid-state batteries depends on electrode materials with high specific capacity. In solid-state batteries, high-nickel ternary materials are commonly used as positive electrodes, and composite materials of silicon compounds and graphite are used as negative electrodes. Although the specific capacity of silicon-based negative electrodes is much higher than that of graphite, they have two major problems: first, the volume expands greatly after lithium insertion, reaching as much as 300% or more, resulting in poor cyclability; second, the initial coulombic efficiency after the full battery is formed is low, which seriously affects the release of battery capacity. The problems of lithium insertion expansion and low initial coulombic efficiency of silicon-based negative electrodes urgently need to be improved. Summary of the Invention

[0003] The embodiments of the present application provide a lithium battery negative electrode and a preparation method thereof, and a lithium battery, so as to solve the technical problems of lithium insertion expansion and low initial coulombic efficiency of silicon-based negative electrodes.

[0004] In a first aspect, an embodiment of the present application provides a lithium battery negative electrode, the lithium battery negative electrode comprising:

[0005] Silicon-based / graphite composite electrode materials;

[0006] Lithium polyanthraquinone imide.

[0007] In some embodiments of the present application, the polyanthraquinone imide structure in the polyanthraquinone imide lithium is formed by polymerization of an aromatic anhydride monomer and an aminoanthraquinone monomer.

[0008] In some embodiments of the present application, the aromatic anhydride monomer includes at least one of pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride; and / or,

[0009] The aminoanthraquinone monomer includes at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

[0010] In some embodiments of the present application, the mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material is 1:(5~20).

[0011] In a second aspect, an embodiment of the present application provides a method for preparing a negative electrode of a lithium battery, the method comprising the following steps:

[0012] dissolving aromatic anhydride monomers and aminoanthraquinone monomers in quinoline, and performing polymerization reaction at a predetermined temperature to obtain polyanthraquinone imide;

[0013] Using the polyanthraquinone imide as a positive electrode and lithium metal as a negative electrode to perform an electrochemical lithium insertion reaction to obtain polyanthraquinone imide lithium;

[0014] The silicon-based / graphite composite electrode material and the polyanthraquinone imide lithium are made into slurry to prepare the lithium battery negative electrode.

[0015] In some embodiments of the present application, the aromatic anhydride monomer includes at least one of pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride; and / or,

[0016] The aminoanthraquinone monomer includes at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

[0017] In some embodiments of the present application, the molar ratio of the aromatic anhydride monomer to the aminoanthraquinone monomer is 1:(0.8-1.2).

[0018] In some embodiments of the present application, the predetermined temperature is 150-210° C.; and / or,

[0019] The duration of the polymerization reaction is 20 to 30 hours.

[0020] In some embodiments of the present application, the mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material is 1:(5~20).

[0021] In a third aspect, an embodiment of the present application provides a lithium battery, comprising the lithium battery negative electrode described in any embodiment of the first aspect, or the lithium battery negative electrode prepared by the method described in any embodiment of the second aspect.

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The lithium battery negative electrode provided in the embodiment of the present application, through the polyanthraquinone imide lithium introduced into the lithium battery negative electrode, can provide additional active lithium ions to the battery system during the cycle, make up for the lithium loss caused by the formation of the SEI film on the negative electrode surface, thereby improving the first coulombic efficiency of the battery and increasing the release of the battery capacity. Furthermore, the polyanthraquinone imide lithium itself has good mechanical properties, solvent resistance, as well as good elasticity and high tensile strength, can withstand the volume change of silicon-based particles during the charge and discharge cycle, prevent the silicon-based negative electrode from pulverizing, thereby improving the long-cycle performance of the battery. In addition, the carbonyl group in the polyanthraquinone imide can also provide additional capacity for the negative electrode during the cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] FIG1 is a schematic flow chart of a method for preparing a negative electrode of a lithium battery provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] Unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. In the event of any conflict, the present specification shall take precedence.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] Existing silicon-based negative electrodes have technical problems such as lithium insertion expansion and low first coulombic efficiency.

[0031] The technical solutions provided in the embodiments of this application are intended to solve the above technical problems, and the overall idea is as follows:

[0032] In a first aspect, an embodiment of the present application provides a lithium battery negative electrode, the lithium battery negative electrode comprising:

[0033] Silicon-based / graphite composite electrode materials;

[0034] Lithium polyanthraquinone imide.

[0035] Silicon-based / graphite composite electrode materials refer to composite electrode materials formed by combining silicon-based electrode materials and graphite electrode materials. This combination can be a simple physical blend, a complex microscopic structure such as a core / shell structure, or a chemical combination. Silicon-based electrode materials and graphite electrode materials are known in the art.

[0036] The polyanthraquinone imide lithium introduced in the negative electrode of the lithium battery in this application can provide additional active lithium ions to the battery system during the cycle, making up for the lithium loss caused by the formation of the SEI film on the negative electrode surface, thereby improving the battery's first coulombic efficiency and increasing the release of battery capacity. Furthermore, polyanthraquinone imide lithium itself has good mechanical properties, solvent resistance, as well as good elasticity and high tensile strength. It can withstand the volume change of silicon-based particles during the charge and discharge cycle, prevent the silicon-based negative electrode from pulverizing, and thus improve the long-cycle performance of the battery. In addition, the carbonyl group in polyanthraquinone imide can also provide additional capacity for the negative electrode during the cycle.

[0037] In some embodiments of the present application, the lithium battery negative electrode further includes a binder and a conductive agent.

[0038] Binders and conductive agents are conventional additives in this field.

[0039] As an example, the binder may be CMC (sodium carboxymethyl cellulose) or SBR (styrene-butadiene rubber).

[0040] As an example, the conductive agent may be carbon black or graphene.

[0041] In some embodiments of the present application, the polyanthraquinone imide structure in the polyanthraquinone imide lithium is formed by polymerization of an aromatic anhydride monomer and an aminoanthraquinone monomer.

[0042] In some embodiments of the present application, the aromatic anhydride monomer includes at least one of pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride; and / or,

[0043] The aminoanthraquinone monomer includes at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

[0044] It is easy to understand that pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride are aromatic anhydride monomers that are relatively easy to obtain on the market. Those skilled in the art may also choose other aromatic anhydride monomers.

[0045] It is easy to understand that, considering the steric hindrance, the amino groups on the aminoanthraquinone monomers should be far apart, so the aminoanthraquinone monomers can be selected from at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

[0046] It is easy to understand that the aromatic anhydride monomers and aminoanthraquinone monomers listed above only contain two polymerizable functional groups, that is, the aromatic anhydride monomers mentioned above only contain two anhydride groups, and the aminoanthraquinone monomers mentioned above only contain two amino groups. These monomers containing only two polymerizable functional groups can be polymerized to form linear polymers, which have relatively low viscosity and good dispersibility. When there are more monomers containing three or more polymerizable functional groups, significant cross-linking will occur, resulting in the formation of polymers with a network structure, which has high viscosity and poor dispersibility. In general, those skilled in the art can choose the aromatic anhydride monomers and aminoanthraquinone monomers listed above. Those skilled in the art can also add monomers containing three or more polymerizable functional groups on their own, which can increase the viscosity of the resulting polyanthraquinone imide lithium at the expense of a certain degree of dispersibility, thereby fine-tuning the overall performance of the lithium battery negative electrode.

[0047] In some embodiments of the present application, the mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material is 1:(5~20).

[0048] As an example, the mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material can be 1:5, 1:7, 1:10, 1:15, 1:18, or 1:20.

[0049] In a second aspect, an embodiment of the present application provides a method for preparing a negative electrode of a lithium battery, the method comprising the following steps:

[0050] S1: dissolving an aromatic anhydride monomer and an aminoanthraquinone monomer in quinoline, and performing a polymerization reaction at a predetermined temperature to obtain polyanthraquinone imide;

[0051] S2: using the polyanthraquinone imide as a positive electrode and lithium metal as a negative electrode to perform an electrochemical lithium insertion reaction to obtain polyanthraquinone imide lithium;

[0052] S3: preparing a lithium battery negative electrode by preparing a slurry of the silicon-based / graphite composite electrode material and the polyanthraquinone imide lithium.

[0053] The preparation of polyanthraquinone imide lithium by electrochemical lithium insertion reaction can make the structure of polyanthraquinone imide lithium more uniform and the combination with lithium ions more complete.

[0054] Electrochemical lithium insertion reaction is a conventional treatment method in the field. In some embodiments of the present application, the electrochemical lithium insertion reaction is carried out in a button cell battery system or a three-electrode system, and the electrolyte is a conventional commercial lithium battery electrolyte. After the button cell battery system or the three-electrode system is assembled, the system is discharged at a current density of less than 0.1C and discharged to 1.5V to complete the lithium insertion of the polyanthraquinone imide to form polyanthraquinone imide lithium.

[0055] The silicon-based / graphite composite electrode material and the polyanthraquinone imide lithium are made into a slurry, which is also called slurrying in the art. Slurrying is a conventional processing method in the art.

[0056] In some embodiments of the present application, the aromatic anhydride monomer includes at least one of pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride; and / or,

[0057] The aminoanthraquinone monomer includes at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

[0058] It is easy to understand that pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride are aromatic anhydride monomers that are relatively easy to obtain on the market. Those skilled in the art may also choose other aromatic anhydride monomers.

[0059] It is easy to understand that, considering the steric hindrance, the amino groups on the aminoanthraquinone monomers should be far apart, so the aminoanthraquinone monomers can be selected from at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

[0060] It is easy to understand that the aromatic anhydride monomers and aminoanthraquinone monomers listed above only contain two polymerizable functional groups, that is, the aromatic anhydride monomers mentioned above only contain two anhydride groups, and the aminoanthraquinone monomers mentioned above only contain two amino groups. These monomers containing only two polymerizable functional groups can be polymerized to form linear polymers, which have relatively low viscosity and good dispersibility. When there are more monomers containing three or more polymerizable functional groups, significant cross-linking will occur, resulting in the formation of polymers with a network structure, which has high viscosity and poor dispersibility. In general, those skilled in the art can choose the aromatic anhydride monomers and aminoanthraquinone monomers listed above. Those skilled in the art can also add monomers containing three or more polymerizable functional groups on their own, which can increase the viscosity of the resulting polyanthraquinone imide lithium at the expense of a certain degree of dispersibility, thereby fine-tuning the overall performance of the lithium battery negative electrode.

[0061] It is easy to understand that the method described in the second aspect of this application can be used to prepare the lithium battery negative electrode described in any embodiment of the first aspect.

[0062] In some embodiments of the present application, the molar ratio of the aromatic anhydride monomer to the aminoanthraquinone monomer is 1:(0.8-1.2).

[0063] In some embodiments of the present application, the predetermined temperature is 150-210° C.; and / or,

[0064] The duration of the polymerization reaction is 20 to 30 hours.

[0065] As an example, the predetermined temperature may be 150°C, 170°C, 180°C, 200°C, or 210°C.

[0066] As an example, the duration of the polymerization reaction may be 20 h, 22 h, 24 h, 26 h, 28 h, or 30 h.

[0067] In some embodiments of the present application, the mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material is 1:(5~20).

[0068] As an example, the mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material can be 1:5, 1:7, 1:10, 1:15, 1:18, or 1:20.

[0069] In a third aspect, an embodiment of the present application provides a lithium battery, comprising the lithium battery negative electrode described in any embodiment of the first aspect, or the lithium battery negative electrode prepared by the method described in any embodiment of the second aspect.

[0070] The lithium battery is realized based on the lithium battery negative electrode described in any embodiment of the first aspect, or the lithium battery negative electrode prepared by the method described in any embodiment of the second aspect. The specific implementation of the lithium battery can refer to the above embodiments and common knowledge in the field. Since the lithium battery adopts part or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0071] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0072] Example 1

[0073] This embodiment provides a method for preparing a negative electrode of a lithium battery, and the method for preparing a negative electrode of a lithium battery comprises the following steps:

[0074] Sa: Naphthalenetetracarboxylic dianhydride and 1,4-diaminoanthraquinone are dissolved in quinoline at a molar ratio of 1:1 to obtain a mixed solution, the mixed solution is heated at 200° C. for 24 hours, and then solid-liquid separation is performed. The obtained solid is washed with N,N-dimethylformamide and anhydrous ethanol in sequence, and vacuum dried to obtain polyanthraquinone imide;

[0075] Sb: The obtained polyanthraquinone imide is used as a positive electrode, lithium metal is used as a negative electrode, and lithium hexafluorophosphate is used as an electrolyte to assemble a button battery, and the button battery is discharged at a discharge current of 0.1C to 1.5V to obtain polyanthraquinone imide lithium;

[0076] Sc: A silicon-based / graphite composite electrode material, lithium polyanthraquinone imide, a binder, and a conductive agent are mixed in a mass ratio of 85.5:9.5:3.5:1.5, desalted water is added to prepare a negative electrode slurry, and the negative electrode slurry is coated on a current collector to obtain a lithium battery negative electrode.

[0077] Among them, the silicon-based / graphite composite electrode material is a mixture of commercial granular silicon oxide material and fast-filling graphite, with a mixing mass ratio of silicon oxide material: graphite = 35:65. The binder is a mixture of CMC and SBR mixed in a mass ratio of 1:1, and the conductive agent is carbon black.

[0078] Example 2

[0079] This embodiment provides a method for preparing a negative electrode of a lithium battery, and the method for preparing a negative electrode of a lithium battery comprises the following steps:

[0080] Sa: Naphthalenetetracarboxylic dianhydride and 2,6-diaminoanthraquinone are dissolved in quinoline at a molar ratio of 1:1 to obtain a mixed solution, the mixed solution is heated at 200° C. for 20 hours, and then solid-liquid separation is performed. The obtained solid is washed with N,N-dimethylformamide and anhydrous ethanol in sequence, and vacuum dried to obtain polyanthraquinone imide;

[0081] Sb: The obtained polyanthraquinone imide is used as a positive electrode, lithium metal is used as a negative electrode, and lithium hexafluorophosphate is used as an electrolyte to assemble a button battery, and the button battery is discharged at a discharge current of 0.1C to 1.5V to obtain polyanthraquinone imide lithium;

[0082] Sc: A silicon-based / graphite composite electrode material, lithium polyanthraquinone imide, a binder, and a conductive agent are mixed in a mass ratio of 85.5:9.5:3.5:1.5, desalted water is added to prepare a negative electrode slurry, and the negative electrode slurry is coated on a current collector to obtain a lithium battery negative electrode.

[0083] Among them, the silicon-based / graphite composite electrode material is a mixture of commercial granular silicon oxide material and fast-filling graphite, with a mixing mass ratio of silicon oxide material: graphite = 35:65. The binder is a mixture of CMC and SBR mixed in a mass ratio of 1:1, and the conductive agent is carbon black.

[0084] Example 3

[0085] This embodiment provides a method for preparing a negative electrode of a lithium battery, and the method for preparing a negative electrode of a lithium battery comprises the following steps:

[0086] Sa: Perylenetetracarboxylic dianhydride and 2,6-diaminoanthraquinone are dissolved in quinoline at a molar ratio of 1:1 to obtain a mixed solution, the mixed solution is heated at 150° C. for 30 hours, and then solid-liquid separation is performed. The obtained solid is sequentially washed with N,N-dimethylformamide and anhydrous ethanol, and vacuum dried to obtain polyanthraquinone imide;

[0087] Sb: The obtained polyanthraquinone imide is used as a positive electrode, lithium metal is used as a negative electrode, and lithium hexafluorophosphate is used as an electrolyte to assemble a button battery, and the button battery is discharged at a discharge current of 0.1C to 1.5V to obtain polyanthraquinone imide lithium;

[0088] Sc: A silicon-based / graphite composite electrode material, lithium polyanthraquinone imide, a binder, and a conductive agent are mixed in a mass ratio of 81:14:3.5:1.5, desalted water is added to prepare a negative electrode slurry, and the negative electrode slurry is coated on a current collector to obtain a lithium battery negative electrode.

[0089] Among them, the silicon-based / graphite composite electrode material is a mixture of commercial granular silicon oxide material and fast-filling graphite, with a mixing mass ratio of silicon oxide material: graphite = 35:65. The binder is a mixture of CMC and SBR mixed in a mass ratio of 1:1, and the conductive agent is carbon black.

[0090] Comparative Example

[0091] This comparative example provides a method for preparing a negative electrode for a lithium battery, and the method for preparing a negative electrode for a lithium battery comprises the following steps:

[0092] A silicon-based / graphite composite electrode material, a binder, and a conductive agent are mixed in a mass ratio of 95:3.5:1.5, desalted water is added to prepare a negative electrode slurry, and the negative electrode slurry is coated on a current collector to obtain a lithium battery negative electrode.

[0093] Among them, the silicon-based / graphite composite electrode material is a mixture of commercial granular silicon oxide material and fast-filling graphite, with a mixing mass ratio of silicon oxide material: graphite = 35:65. The binder is a mixture of CMC and SBR mixed in a mass ratio of 1:1, and the conductive agent is carbon black.

[0094] Related experiments and effect data:

[0095] The lithium battery negative electrodes prepared in Examples 1 to 3 and the comparative example were made into lithium batteries, wherein the positive electrode material of the lithium battery was lithium nickel cobalt aluminum oxide, and the electrolyte was polyethylene oxide solid electrolyte.

[0096] Electrochemical tests were performed on the lithium batteries corresponding to Examples 1 to 3 and the comparative example, and the obtained initial charge specific capacity, initial coulombic efficiency, and cycle life after 100 cycles are shown in Table 1.

[0097] Example 1 Example 2 Example 3 Comparative Example First charge specific capacity 611mAh / g 602mAh / g 591mAh / g 601mAh / g First coulombic efficiency 93.0% 94.1% 96.8% 88.5% Cycle life 100 weeks Remaining 94.5% 95.4% 98.8% 89.0%

[0098] Table 1

[0099] The only difference between Examples 1-3 and the Comparative Example is that the polyanthraquinone imide lithium component in Examples 1-3 is replaced by an equal mass of silicon-based / graphite composite electrode material in the Comparative Example. Comparing the data of Examples 1-3 and the Comparative Example, it is found that the initial charge specific capacity of Examples 1-3 is at the same level as that of the Comparative Example, while the initial coulombic efficiency of Examples 1-3 is significantly improved compared to that of the Comparative Example. The cycle life of Examples 1-3 after 100 cycles is also significantly improved compared to that of the Comparative Example. This shows that replacing a portion of the silicon-based / graphite composite electrode material with the polyanthraquinone imide lithium component can effectively improve the initial coulombic efficiency and cycle life after 100 cycles of the corresponding lithium battery.

[0100] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the present application. Therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0101] In this application, unless otherwise indicated, directional terms such as "upper" and "lower" refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of this application specification, the terms "include", "comprise", etc. mean "including but not limited to". Moreover, the terms "include", "comprises", or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. In the absence of further restrictions, the elements defined by the phrase "include..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements. In this document, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this document, "and / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. When the expression "and / or" is used to describe a relationship involving three or more associated items, it means that any one of the three associated items can exist alone, or at least two of them can exist simultaneously. For example, "A," "and / or B," and / or "C" can mean that any one of A, B, and C exists alone, any two of them exist simultaneously, or all three of them exist simultaneously. As used herein, "at least one" means one or more, and "plurality" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can mean: a, b, c, a+b (i.e., a and b), a+c, b+c, or a+b+c, where a, b, and c can each be single or plural.

[0102] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A lithium battery negative electrode, characterized in that The lithium battery negative electrode comprises: Silicon-based / graphite composite electrode materials; Lithium polyanthraquinone imide.

2. The lithium battery negative electrode according to claim 1, characterized in that The polyanthraquinone imide structure in the polyanthraquinone imide lithium is formed by polymerization of an aromatic anhydride monomer and an aminoanthraquinone monomer.

3. The lithium battery negative electrode according to claim 2, characterized in that The aromatic anhydride monomer includes at least one of pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride; and / or, The aminoanthraquinone monomer includes at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

4. The lithium battery negative electrode according to claim 2, characterized in that The mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material is 1:(5-20).

5. A method for preparing a negative electrode of a lithium battery, characterized in that: The method for preparing the negative electrode of the lithium battery comprises the following steps: dissolving aromatic anhydride monomers and aminoanthraquinone monomers in quinoline, and performing polymerization reaction at a predetermined temperature to obtain polyanthraquinone imide; Using the polyanthraquinone imide as a positive electrode and lithium metal as a negative electrode to perform an electrochemical lithium insertion reaction to obtain polyanthraquinone imide lithium; The silicon-based / graphite composite electrode material and the polyanthraquinone imide lithium are made into slurry to prepare the lithium battery negative electrode.

6. The method for preparing a negative electrode for a lithium battery according to claim 5, wherein: The aromatic anhydride monomer includes at least one of pyromellitic dianhydride, naphthalenetetracarboxylic dianhydride or perylenetetracarboxylic dianhydride; and / or, The aminoanthraquinone monomer includes at least one of 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone or 2,6-diaminoanthraquinone.

7. The method for preparing a negative electrode for a lithium battery according to claim 6, wherein: The molar ratio of the aromatic anhydride monomer to the aminoanthraquinone monomer is 1:(0.8-1.2).

8. The method for preparing a negative electrode for a lithium battery according to claim 5, wherein: The predetermined temperature is 150-210° C.; and / or, The duration of the polymerization reaction is 20 to 30 hours.

9. The method for preparing a negative electrode for a lithium battery according to claim 5, wherein: The mass ratio of the polyanthraquinone imide lithium to the silicon-based / graphite composite electrode material is 1:(5-20).

10. A lithium battery, characterized in that: The lithium battery comprises the lithium battery negative electrode according to any one of claims 1 to 4, or the lithium battery negative electrode prepared by the method according to any one of claims 5 to 9.

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