Preparation method of lithium battery negative electrode and lithium battery

Abstract

The application relates to a preparation method of a lithium battery negative electrode and a lithium battery, and relates to the new energy field.The method comprises the following steps: providing foamed nickel with a porous structure; placing the foamed nickel in a predetermined electrolyte for electrodeposition to prepare polypyrrole on the surface of the foamed nickel, so as to obtain a prefabricated current collector coated with polypyrrole on the surface; performing heat treatment on the prefabricated current collector in an inert atmosphere, so that the polypyrrole on the surface of the prefabricated current collector is carbonized, and a current collector with the porous structure is obtained; and preparing lithium metal on the surface of the current collector, so as to obtain the lithium battery negative electrode, wherein the predetermined electrolyte is an electrolyte containing pyrrole.The preparation method of the lithium battery negative electrode has the beneficial effect of making the deposition and peeling of lithium metal more ordered.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy, in particular to a lithium battery. BACKGROUND

[0002] Lithium metal is considered as one of the most promising anode materials for lithium batteries due to its high specific capacity, low operating potential and high energy density. Guiding the ordered deposition and stripping of lithium metal and inhibiting the growth of lithium dendrites and the volume expansion during lithium deposition and detachment can effectively improve the coulombic efficiency and cycle life of lithium metal anode. Loading lithiumophilic materials on the current collector is beneficial to guiding the ordered deposition of lithium metal. Nitrogen-containing compounds have been confirmed to be materials with high lithiumophilic property, and are currently loaded on the surface of the current collector as lithiumophilic materials. However, although loading nitrogen-containing compounds on the surface of the current collector can make the deposition and stripping of lithium metal more ordered, the lithiumophilic sites are still very limited, and the improvement effect of the order of the deposition and stripping of lithium metal also needs to be improved. SUMMARY

[0003] Embodiments of the present application provide a preparation method of a lithium battery anode and a lithium battery to solve the technical problem that the improvement effect of the order of the deposition and stripping of lithium metal by loading nitrogen-containing compounds on the surface of the current collector needs to be improved.

[0004] In a first aspect, embodiments of the present application provide a preparation method of a lithium battery anode, which comprises the following steps:

[0005] providing a foamed nickel with a porous structure;

[0006] electrodepositing the foamed nickel in a predetermined electrolyte to prepare polypyrrole on the surface of the foamed nickel, to obtain a pre-prepared current collector coated with polypyrrole on the surface;

[0007] heat-treating the pre-prepared current collector in an inert atmosphere to carbonize the polypyrrole on the surface of the pre-prepared current collector, to obtain a current collector with the porous structure;

[0008] preparing lithium metal on the surface of the current collector to obtain the lithium battery anode,

[0009] wherein the predetermined electrolyte is an electrolyte containing pyrrole.

[0010] In some embodiments of the present application, the step of preparing lithium metal on the surface of the current collector comprises the following steps:

[0011] filling molten lithium metal into the porous structure of the current collector in an inert atmosphere;

[0012] cooling and solidifying the molten lithium metal in the porous structure of the current collector to obtain the lithium battery anode.

[0013] In some embodiments of the present application, the filling of the molten lithium metal into the porous structure of the current collector in the inert atmosphere comprises the following steps:

[0014] In the inert atmosphere, the current collector is immersed into the molten lithium metal for at least 5 min, so that the molten lithium metal fills into the porous structure of the current collector.

[0015] In some embodiments of the present application, the preparation of the lithium metal on the surface of the current collector is performed in a glove box.

[0016] In some embodiments of the present application, the electrolyte in the predetermined electrolyte solution comprises a lithium salt.

[0017] In some embodiments of the present application, the predetermined electrolyte solution is an aqueous solution, the lithium salt is lithium carbonate, and the electrolyte in the predetermined electrolyte solution further comprises a cationic lithium-free water-soluble carbonate.

[0018] In some embodiments of the present application, the temperature of the heat treatment is 800-1000℃; and / or,

[0019] The time of the heat treatment is 1-3h.

[0020] In the second aspect, the embodiments of the present application provide a lithium battery, wherein the negative electrode of the lithium battery is prepared by the method of any one of the embodiments of the first aspect.

[0021] In some embodiments of the present application, the lithium battery further comprises a separator and a liquid electrolyte.

[0022] In some embodiments of the present application, the lithium battery further comprises a solid-state electrolyte.

[0023] Compared with the prior art, the above technical solutions provided by the embodiments of the present application have the following advantages:

[0024] The preparation method of the lithium battery negative electrode provided by the embodiments of the present application deposits a layer of polypyrrole on the surface of the foamed nickel by electrodeposition, and then carbonizes the polypyrrole to obtain a current collector coated with nitrogen-doped carbon. Since the nitrogen content of polypyrrole is high, the nitrogen-doped carbon has abundant nitride lithium-philic sites. In addition, the surface of the current collector coated with nitrogen-doped carbon has a relatively large contact area with lithium metal, so there are a large number of nitride lithium-philic sites on the surface of the current collector, which can effectively guide the ordered deposition and stripping of lithium metal, thereby improving the coulombic efficiency and cycle life of the lithium metal negative electrode. In addition, the matrix material of the current collector is foamed nickel, which has a porous structure similar to that of foamed nickel. The porous structure can accommodate lithium dendrites and limit the growth of lithium dendrites, which can further make the deposition and stripping of lithium metal more ordered. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application.

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings required to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings from these drawings without any creative effort.

[0027] Figure 1 A flowchart of a preparation method of a lithium battery negative electrode provided by the embodiments of the present application. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0029] Unless otherwise specifically defined, the terms used herein are understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs. In case of conflict, the present specification prevails.

[0030] Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0031] At present, there is a technical problem that the improvement effect of the improvement of the orderliness of the deposition and stripping of lithium metal on the surface of the current collector loaded with nitrogen-containing compounds needs to be improved.

[0032] The technical solutions provided by the embodiments of the present application are as follows to solve the above technical problems:

[0033] In a first aspect, the embodiments of the present application provide a preparation method of a lithium battery negative electrode, which comprises the following steps:

[0034] S1: providing a foamed nickel with a porous structure;

[0035] S2: placing the nickel foam into a predetermined electrolyte for electrodeposition to prepare polypyrrole on the surface of the nickel foam, to obtain a pre-prepared current collector coated with polypyrrole on the surface;

[0036] S3: heat treating the pre-prepared current collector under an inert atmosphere to carbonize the polypyrrole on the surface of the pre-prepared current collector, to obtain a current collector with the porous structure;

[0037] S4: preparing lithium metal on the surface of the current collector, to obtain the lithium battery negative electrode,

[0038] wherein the predetermined electrolyte is an electrolyte containing pyrrole.

[0039] The nickel foam has a three-dimensional full-through mesh structure and is a porous metal material, with a porosity of 96-98% and a bulk density of only one-fiftieth of that of nickel. The nickel skeleton is hollow and interconnected in a metallurgical state. The nickel foam has the following physical properties: 1. Large specific surface area: This property makes it perform well in many application scenarios, for example, when used as a catalytic carrier substrate, it can provide more reaction sites; 2. Good thermal conductivity: It can effectively conduct heat and can be used as a damping material or a high-efficiency heat-conducting "wick" material for heat pipes in the thermal engineering field, doubling the efficiency; 3. Wide-frequency sound absorption characteristics: In the field of functional materials, it can be used as a damping material to absorb wave energy, and can also be used for sound absorption, vibration absorption, and cushioning; 4. Strong processability: It can be cut, bent, and simply pasted, making it easy to process and use according to actual needs; 5. Homogeneous three-dimensional network structure: This structure makes the nickel foam have filtering effect, and the flow stability of gas and fluid during filtering is super strong. The application selects the nickel foam as the substrate material of the current collector, which has the beneficial effect that the nickel foam has a rich porous structure inside which can be used to accommodate lithium metal, the current collector still retains this porous structure, and the deposition of lithium metal can be carried out inside the current collector, the influence of lithium dendrites on the separator is small; The deposition of lithium metal in the small porous structure limits the growth of lithium dendrites, reducing the uneven growth of lithium dendrites, thereby increasing the orderliness of the lithium metal deposition and stripping process. In addition, the nickel foam as a starting material has good electrical conductivity and electrolyte permeability due to its porous structure, providing an ideal substrate for subsequent lithium metal deposition.

[0040] The application can prepare lithium metal on the surface of the current collector by any implementable method. As an example, the application can prepare lithium metal on the surface of the current collector by electrochemical deposition, vapor deposition, immersion hot melting lithium metal, etc. It should be noted that the current collector structure of the application is based on nickel foam, which has a rich porous structure, and the surface of the current collector includes not only the visible external surface but also the internal surface formed by the porous structure.

[0041] In some embodiments, for electrochemical deposition, the application can assemble the current collector as an initial lithium-free negative electrode with a lithium-rich positive electrode material into a pre-lithium battery with lithium-free negative electrode, and achieve deposition of lithium metal on the current collector by charging the pre-lithium battery.

[0042] It is easy to understand that the nitrogen content of polypyrrole is high, which is a polymer polymerized from pyrrole monomer, has a conjugated structure, and from the microstructure, polypyrrole is described as quasi-one-dimensional and one-dimensional, because there are some cross-linking and jumping chains, and its polymerization degree is different and presents different states, undoped and doped polypyrrole is insoluble in solvent but can swell, doping can make it brittle, the surface of polypyrrole material presents fractal characteristics, and ion diffusion shows an abnormal diffusion mode. After carbonization of the polypyrrole on the surface of the pre-current collector, nitrogen-doped carbon with rich nitride lithium-philic sites is formed. And because the pre-current collector is coated with polypyrrole after electrochemical deposition, the current collector formed after carbonization of the polypyrrole on the surface of the pre-current collector is also in the form of being coated with nitrogen-doped carbon on the surface. As a conductive polymer, polypyrrole can further enhance the conductivity of the current collector, and its unique chemical properties are helpful to the subsequent carbonization process.

[0043] The application deposits a layer of polypyrrole on the surface of the foamed nickel by electrochemical deposition, and then carbonizes the polypyrrole to obtain a current collector coated with nitrogen-doped carbon on the surface. Because the nitrogen content of polypyrrole is high, the nitrogen-doped carbon has rich nitride lithium-philic sites. And because the surface of the current collector coated with nitrogen-doped carbon has a large overall contact area with lithium metal, there are a large number of nitride lithium-philic sites on the surface of the current collector, which can effectively guide the ordered deposition and stripping of lithium metal, thereby improving the coulombic efficiency and cycle life of the lithium metal negative electrode. In addition, the matrix material of the current collector is foamed nickel, which has a porous structure similar to that of foamed nickel, and the porous structure can accommodate lithium dendrites and limit the growth of lithium dendrites, which can further make the deposition and stripping of lithium metal more ordered. The carbonization process not only improves the thermal stability and chemical stability of the current collector, but also provides a more uniform and stable interface for subsequent lithium metal deposition.

[0044] In some embodiments of the application, the step of preparing lithium metal on the surface of the current collector includes the following steps:

[0045] S31: filling molten lithium metal into the porous structure of the current collector in an inert atmosphere;

[0046] S32: cooling and solidifying the molten lithium metal in the porous structure of the current collector to obtain the lithium battery negative electrode.

[0047] It is easy to understand that the mechanical processing performance of lithium metal is poor, the chemical reactivity with moisture and oxygen under ambient conditions is high, and the electrochemical reversibility is also poor, which makes the ultra-thin lithium metal negative electrode prepared by mechanical processing or in the way of electrochemical deposition have high requirements for the preparation process and the preparation environment. The present application only needs to provide an inert atmosphere and heating conditions that can melt lithium metal by filling molten lithium metal into the porous structure of the current collector, which is relatively simple to implement, and lithium metal can be more fully filled into the porous structure of the current collector.

[0048] In addition, it needs to be explained that the nitrogen-doped carbon has chemical inertness and good affinity to the strong reducing molten lithium metal.

[0049] In some embodiments of the present application, the step of filling the molten lithium metal into the porous structure of the current collector in an inert atmosphere comprises the following steps:

[0050] S311: soaking the current collector in the molten lithium metal in an inert atmosphere for at least 5 min, so that the molten lithium metal fills into the porous structure of the current collector.

[0051] In some embodiments of the present application, the preparation of lithium metal on the surface of the current collector is carried out in a glove box.

[0052] It is easy to understand that the glove box is a commonly used device in the field of lithium batteries and can provide an inert atmosphere and heating conditions.

[0053] In some embodiments of the present application, the electrolyte in the predetermined electrolyte solution comprises a lithium salt.

[0054] It is easy to understand that the beneficial effect of the electrolyte in the predetermined electrolyte solution comprising a lithium salt is that lithium ions exist in the polypyrrole, and finally lithium ions exist in the nitrogen-doped carbon, which is beneficial to increase the affinity of the nitrogen-doped carbon to the molten lithium metal, thereby increasing the wetting ability of the molten lithium metal on the surface of the nitrogen-doped carbon.

[0055] In some embodiments of the present application, the predetermined electrolyte solution is an aqueous solution, the lithium salt is lithium carbonate, and the electrolyte in the predetermined electrolyte solution further comprises a water-soluble carbonate salt with no lithium in the cation.

[0056] The aqueous solution has the beneficial effect of being inexpensive and easy to prepare.

[0057] The water-soluble carbonate salt functions to further increase the conductivity of the predetermined electrolyte solution.

[0058] In some embodiments of the present application, the temperature of the heat treatment is 800-1000℃; and / or,

[0059] The time of the heat treatment is 1-3h.

[0060] The temperature of the heat treatment is 800-1000℃, which has the beneficial effect of reducing energy consumption as much as possible while ensuring sufficient carbonization of the polypyrrole.

[0061] The time of the heat treatment is 1-3h, which has the beneficial effect of reducing energy consumption as much as possible while ensuring sufficient carbonization of the polypyrrole.

[0062] As an example, the temperature of the heat treatment can be 800℃, 850℃, 900℃, 950℃, 1000℃

[0063] As an example, the time of the heat treatment can be 1h, 1.5h, 2h, 2.5h, 3h.

[0064] In summary, the embodiment of the present application provides a preparation method of a lithium battery negative electrode, which has the following technical advantages:

[0065] 1. Ordering of lithium metal deposition and stripping:

[0066] Through the preparation method, especially the introduction and carbonization treatment of polypyrrole, the deposition and stripping behavior of lithium metal on the surface of the current collector is effectively improved. The carbon layer provides a more uniform and stable deposition interface, which helps to reduce the dendrite growth of lithium metal during charging and discharging, thereby prolonging the service life and safety of the battery.

[0067] 2. Improving battery performance:

[0068] The ordered lithium metal deposition and stripping process helps to improve the cycle stability and coulombic efficiency of the battery. In addition, the introduction of the porous nickel foam and the carbon layer also enhances the electrical conductivity and electrolyte permeability of the battery, further improving the overall performance of the battery.

[0069] 3. Application prospect

[0070] The preparation method of the lithium battery negative electrode and the lithium battery provided by the present application have wide application prospects in the fields of new energy vehicles, energy storage systems, etc. By optimizing the negative electrode structure, not only the energy density and cycle life of the lithium battery can be improved, but also the cost and environmental impact of the battery can be reduced, contributing to the development of the new energy industry.

[0071] Therefore, through the innovative preparation method and material selection, the present application successfully realizes the optimization of the negative electrode structure of the lithium battery, providing a new idea and solution for improving the performance of the lithium battery and promoting the development of the new energy industry.

[0072] In a second aspect, the embodiment of the present application provides a lithium battery, wherein the negative electrode of the lithium battery is prepared by the method of any one of the first aspect.

[0073] The lithium battery is implemented by the lithium battery negative electrode prepared by the method of any one of the first aspect, and the specific embodiments of the lithium battery can refer to the above embodiments and the common knowledge in the art. Since the lithium battery adopts part or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0074] In some embodiments of the present application, the lithium battery further comprises a separator and a liquid electrolyte.

[0075] It is easy to understand that the lithium battery negative electrode described in the present application has lithium dendrites mainly existing in the porous structure of the current collector, and less lithium dendrites are generated on the surface of the current collector in contact with the separator, so the lithium battery negative electrode described in the present application can be applied to the traditional lithium battery comprising a separator and a liquid electrolyte.

[0076] In some embodiments of the present application, the lithium battery further comprises a solid-state electrolyte.

[0077] It is easy to understand that the lithium battery negative electrode described in the present application is suitable for a lithium battery without a separator and using a solid-state electrolyte.

[0078] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods not specified in the following embodiments are generally determined according to the industry standard. If there is no corresponding industry standard, it is determined according to the general international standard, the conventional condition, or according to the conditions suggested by the manufacturer.

[0079] Example 1

[0080] The present embodiment provides a lithium battery negative electrode, which is prepared by the following method:

[0081] 1.5 g of lithium carbonate, 3 g of sodium carbonate and 2 g of pyrrole were added to 200 mL of water, stirred for 30 min to obtain a pre-prepared electrolyte;

[0082] A foamed nickel was used as a working electrode, a carbon rod was used as a reference and counter electrode, the pre-prepared electrolyte was used as an electrolyte, a constant potential oxidation method was used, a voltage of 0.8 V was used, and the reaction was continued for 10 min to obtain a pre-prepared current collector;

[0083] The pre-prepared current collector was placed in a tube furnace and reacted at 800℃ for 2 h in an Ar atmosphere to obtain a current collector;

[0084] In a nitrogen-filled glove box, the current collector was immersed in molten metal Li, and after 5 minutes, a lithium battery negative electrode was obtained.

[0085] The embodiment also provides a lithium battery prepared by the following method.

[0086] A positive electrode tab is provided, which is composed of a positive electrode active material, a conductive agent, and a binder in a mass ratio of 95:3:2, wherein the positive electrode active material is lithium cobaltate, the conductive agent is SUPER P carbon black, and the binder is sodium carboxymethyl cellulose.

[0087] A polyethylene diaphragm and an electrolyte are provided, wherein the electrolyte is a vinyl carbonate solution of lithium hexafluorophosphate.

[0088] The positive electrode tab and the polyethylene diaphragm are stacked in a Z-shaped stack, and then subjected to welding, liquid injection, pre-charging, two-sealing, and formation processes to obtain a 1 Ah lithium battery.

[0089] Embodiment 2

[0090] The embodiment differs from Embodiment 1 only in that the temperature for carbonizing the polypyrrole is 900°C.

[0091] The embodiment is specifically as follows:

[0092] The embodiment provides a lithium battery negative electrode prepared by the following method.

[0093] 1.5 g of lithium carbonate, 3 g of sodium carbonate, and 2 g of pyrrole are added to 200 mL of water, and stirred for 30 min to obtain a pre-prepared electrolyte;

[0094] A foamed nickel is used as a working electrode, a carbon rod is used as a reference electrode and a counter electrode, the pre-prepared electrolyte is used as an electrolyte, a constant potential oxidation method is adopted, a voltage of 0.8 V is used, and the reaction is continued for 10 min to obtain a pre-prepared current collector;

[0095] The pre-prepared current collector is placed in a tube furnace, and is reacted for 2 h under an Ar atmosphere at 900°C to obtain a current collector.

[0096] In a nitrogen-filled glove box, the current collector is immersed in molten metal Li, and is taken out after 5 min to obtain a lithium battery negative electrode.

[0097] The embodiment also provides a lithium battery prepared by the following method.

[0098] A positive electrode tab is provided, which is composed of a positive electrode active material, a conductive agent, and a binder in a mass ratio of 95:3:2, wherein the positive electrode active material is lithium cobaltate, the conductive agent is SUPER P carbon black, and the binder is sodium carboxymethyl cellulose.

[0099] A polyethylene diaphragm and an electrolyte are provided, wherein the electrolyte is a vinyl carbonate solution of lithium hexafluorophosphate.

[0100] The positive electrode sheet, the polyethylene diaphragm are stacked in Z-shaped stack mode, and a 1 Ah lithium battery is prepared through welding, liquid injection, pre-charging, two-sealing, and formation process.

[0101] Example 3

[0102] The difference between this embodiment and Example 1 is that the temperature of polypyrrole carbonization is 1000℃.

[0103] This embodiment is specifically as follows:

[0104] This embodiment provides a lithium battery negative electrode, which is prepared by the following method:

[0105] 1.5 g of lithium carbonate, 3 g of sodium carbonate, and 2 g of pyrrole are added to 200 mL of water, and stirred for 30 min to obtain a pre-prepared electrolyte;

[0106] A foamed nickel is used as a working electrode, a carbon rod is used as a reference and counter electrode, the pre-prepared electrolyte is used as an electrolyte, a constant potential oxidation method is used, a voltage of 0.8 V is used, and a reaction is continued for 10 min to obtain a pre-prepared current collector;

[0107] The pre-prepared current collector is placed in a tube furnace, reacted for 2 h under Ar atmosphere and at 1000℃ to obtain a current collector;

[0108] In a nitrogen-filled glove box, the current collector is immersed in molten metal Li, taken out after 5 min to obtain a lithium battery negative electrode.

[0109] This embodiment also provides a lithium battery, which is prepared by the following method:

[0110] A positive electrode sheet is provided, which is composed of positive electrode active material, conductive agent, and binder in a mass ratio of 95:3:2, wherein the positive electrode active material is lithium cobaltate, the conductive agent is SUPERP carbon black, and the binder is sodium carboxymethyl cellulose;

[0111] A polyethylene diaphragm and an electrolyte are provided, and the electrolyte is a vinyl carbonate solution of lithium hexafluorophosphate;

[0112] The positive electrode sheet and the polyethylene diaphragm are stacked in Z-shaped stack mode, and a 1 Ah lithium battery is prepared through welding, liquid injection, pre-charging, two-sealing, and formation process.

[0113] Comparative Example

[0114] The difference between this comparative example and Example 1 is that the foamed nickel is directly used as a current collector in this comparative example.

[0115] Specifically as follows:

[0116] The comparative example provides a lithium battery negative electrode prepared by the following method:

[0117] In a nitrogen-filled glove box, the foamed nickel is immersed in molten metal Li, and after 5 minutes, the lithium battery negative electrode is obtained.

[0118] The example also provides a lithium battery prepared by the following method:

[0119] A positive electrode tab is provided, which is composed of a positive electrode active material, a conductive agent, and a binder in a mass ratio of 95:3:2, wherein the positive electrode active material is lithium cobaltate, the conductive agent is SUPERP carbon black, and the binder is sodium carboxymethyl cellulose.

[0120] A polyethylene separator and an electrolyte are provided, and the electrolyte is a vinyl carbonate solution of lithium hexafluorophosphate.

[0121] The positive electrode tab and the polyethylene separator are stacked in a Z-shaped stack, and after welding, liquid injection, pre-charging, two-sealing, and formation processes, a 1 Ah lithium battery is prepared.

[0122] Related experiments and effect data:

[0123] The lithium batteries of Examples 1-3 and the comparative example are subjected to cyclic charge-discharge tests at a current of 1C, and the capacity retention rate after 30 cycles and the cycle number of 80% capacity retention are obtained and shown in Table 1.

[0124] Table 1

[0125] Capacity retention after 30 cycles Number of cycles for 80% capacity retention Example 1 94％ 200 Example 2 95％ 280 Example 2 90％ 170 Comparative Example 1 83％ 40

[0126] From Table 1, it can be found that for the lithium batteries provided in Examples 1-3, the capacity retention rate after 30 cycles and the cycle number of 80% capacity retention are both at a high level. However, for the lithium battery provided in the comparative example, the capacity retention rate after 30 cycles and the cycle number of 80% capacity retention are both significantly lower than those of Examples 1-3. This indicates that for the lithium batteries in Examples 1-3, the nitrogen-doped carbon coating on the surface of the current collector can effectively improve the orderliness of lithium metal deposition and stripping, thereby having good cycle performance.

[0127] Various embodiments of this application may exist 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 this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has 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., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0128] In the present application, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings unless otherwise stated. In addition, in the description of the present application, the terms "comprise", "contain" and the like mean "comprise but not limited to". Moreover, the terms "comprise", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitation, the elements defined by the statement "comprise" do not exclude the presence of other identical elements in the process, method, article or device comprising the elements. In this text, the relationship terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In this text, the association relationship of the associated objects described by "and / or" indicates that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist simultaneously, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of the three associated objects can exist alone, or any at least two of them exist simultaneously, for example, for A, and / or B, and / or C, it means that any one of A, B and C exists alone, or any two of them exist simultaneously, or all three exist simultaneously. In this text, "at least one" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of these items, including any combination of single or multiple 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 be single or multiple. The "fractional representation method" referred to in the present application, such as weight parts, mass parts, etc., represents the proportional relationship between the components. In the proportional relationship referred to in the present application, the parameters that need to be described by the proportion should be understood as the front item of the proportion formula in the order of description, and the proportion number should be understood as the rear item of the proportion formula, for example, the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should be one-to-one corresponding in the proportion formula according to the description order, i.e. the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0129] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this 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 this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a lithium battery negative electrode, characterized in that, The method includes the following steps: Provides nickel foam with a porous structure; The nickel foam is placed in a predetermined electrolyte for electrodeposition to prepare polypyrrole on the surface of the nickel foam, thereby obtaining a preformed current collector coated with polypyrrole. The pre-fabricated current collector is heat-treated under an inert atmosphere to carbonize the polypyrrole on the surface of the pre-fabricated current collector, thereby obtaining a current collector with nitrogen-doped carbon on its surface. Lithium metal is prepared on the surface of the current collector to obtain the negative electrode of the lithium battery. The predetermined electrolyte is a pyrrole-containing electrolyte, the electrolyte in the predetermined electrolyte includes a lithium salt, the predetermined electrolyte is an aqueous solution, the lithium salt is lithium carbonate, and the electrolyte in the predetermined electrolyte also includes a water-soluble carbonate with a non-lithium cationic form.

2. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The preparation of lithium metal on the surface of the current collector includes the following steps: Molten lithium metal is filled into the porous structure of the current collector in an inert atmosphere; The molten lithium metal in the porous structure of the current collector is cooled and solidified to obtain the negative electrode of the lithium battery.

3. The method for preparing a lithium battery negative electrode according to claim 2, characterized in that, The step of filling the porous structure of the current collector with molten lithium metal in an inert atmosphere includes the following steps: In an inert atmosphere, the current collector is immersed in molten lithium metal for at least 5 minutes, so that the molten lithium metal fills the porous structure of the current collector.

4. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The preparation of lithium metal on the surface of the current collector is carried out in a glove box.

5. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The heat treatment temperature is 800~1000℃; and / or, The heat treatment time is 1 to 3 hours.

6. A lithium battery, characterized in that, The negative electrode of the lithium battery is the negative electrode of the lithium battery prepared by the method described in any one of claims 1 to 5.

7. The lithium battery according to claim 6, characterized in that, The lithium battery also includes a separator and a liquid electrolyte.

8. The lithium battery according to claim 6, characterized in that, The lithium battery also includes a solid electrolyte.

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