Negative electrode material, sodium ion battery and electronic equipment

Abstract

The embodiment of the invention provides a negative electrode material, a sodium ion battery and electronic equipment, and relates to the technical field of batteries, the negative electrode material comprises a carbon microcrystalline structure, the carbon microcrystalline structure comprises sp2 hybrid carbon, and the sp2 hybrid carbon accounts for 40%-58% of the mass of the carbon microcrystalline structure. By regulating and controlling the content of sp2 hybrid carbon in the negative electrode material, the negative electrode material has relatively high conductivity and is beneficial to improving the conductivity of the sodium ion battery.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and in particular, to a negative electrode material, a sodium-ion battery, and an electronic device. Background Art

[0002] With the development of large-scale energy storage technologies, electrochemical energy storage technologies have good application prospects in large-scale energy storage demonstration projects, base stations, etc. Sodium-ion batteries have the advantages of rich reserves, low cost, high safety, etc., and can be widely used in large-scale energy storage scenarios.

[0003] As an important part of sodium-ion batteries, the performance of negative electrode materials largely determines the energy density and cycle life of the batteries. Usually, carbonaceous negative electrode materials are used as the negative electrode materials of the batteries. How to improve the electrical conductivity of negative electrode materials is an urgent problem to be solved in this field. Summary of the Invention

[0004] Embodiments of this application provide a negative electrode material, a sodium-ion battery, and an electronic device. By regulating the content of sp 2 hybridized carbon in the negative electrode material, the negative electrode material has a high electrical conductivity and is beneficial to improving the electrical conductivity of sodium-ion batteries.

[0005] To achieve the above object, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, embodiments of this application provide a negative electrode material, which includes a carbon microcrystal structure. The carbon microcrystal structure includes sp 2 hybridized carbon, and the mass percentage of sp 2 hybridized carbon in the carbon microcrystal structure is 40%-58%.

[0007] On the one hand, the negative electrode material includes a carbon microcrystal structure. The carbon microcrystal structure includes sp 2 hybridized carbon. The sp 2 hybridized carbon belongs to a planar structure, which can make the carbon microcrystal structure have a good ordered stacked planar structure. Thus, the electrical conductivity of the negative electrode material can be improved. Furthermore, the electrical conductivity of the negative electrode plate in the sodium-ion battery can be improved, and to a certain extent, the rapid diffusion of sodium ions is promoted, and the current performance of the sodium-ion battery is improved.

[0008] On the other hand, embodiments of this application can also regulate the content of sp 2 hybridized carbon, which can make the carbon microcrystal structure have a good and ordered layered structure, and further ensure a good size of the carbon microcrystal structure. Thus, the electrical conductivity and the compaction density of the negative electrode material can be further improved. Furthermore, the electrochemical sodium storage capacity of the negative electrode material is improved.

[0009] In a feasible manner, sp2 The mass percentage of hybrid carbon in the carbon microcrystalline structure is 50%-58%.

[0010] In this way, the embodiment of the present application can be used for sp 2 The content of hybrid carbon is further regulated to induce the short-range ordered arrangement of the carbon microcrystalline structure, ensuring a better flat layer stacking structure and carbon microcrystalline structure size in the negative electrode material. On the basis of ensuring the sodium deintercalation capacity of the negative electrode material, the high compaction density and high electrochemical sodium storage capacity characteristics of the negative electrode material are achieved, which can effectively improve the energy density of sodium-ion batteries.

[0011] In one achievable manner, the carbon microcrystalline structure includes a plurality of stacked carbon layers, and the interlayer spacing between the plurality of carbon layers is 0.35 nm-0.38 nm.

[0012] Thus, the interlayer spacing d002 between the multiple carbon layers provided in the embodiment of the present application is 0.35nm-0.38nm, and the distance between the multiple layered structures is small, which can improve the conductivity and compaction density of the negative electrode material, thereby ensuring the electrochemical performance of the sodium ion battery.

[0013] In one achievable manner, the length of the carbon microcrystalline structure is 2 nm to 5.5 nm.

[0014] Thus, the carbon microcrystalline structure in the embodiment of the present application has a more suitable size, so that it has a higher electrical conductivity while taking into account the efficient storage of sodium ions.

[0015] In one achievable manner, the number n of carbon layers is: 2≤n≤5.

[0016] Thus, the carbon microcrystalline structure in the embodiment of the present application has a certain number of carbon layers, which can maintain a relatively suitable flat layer stacking structure, so that it has a higher conductivity, which can improve the conductivity of the negative electrode material. Furthermore, it can improve the conductivity of the negative electrode sheet in the sodium ion battery.

[0017] In one achievable manner, the conductivity of the negative electrode material is 50 S / cm-80 S / cm.

[0018] Thus, the negative electrode material provided in the embodiment of the present application has a high electrical conductivity, which can significantly improve the electron transport characteristics inside the negative electrode material, reduce the polarization of the negative electrode material, and further improve the electrochemical performance of the sodium ion battery.

[0019] In one achievable manner, the compacted density of the negative electrode material is 0.95 g / cm 3 -1.1g / cm 3 .

[0020] Thus, the negative electrode material provided by the embodiments of the present application has a high tap density, which can improve the volumetric energy density of the sodium-ion battery.

[0021] In an implementable manner, the oxygen content of the negative electrode material is 0.5%-5%, and the nitrogen content of the negative electrode material is 0.5%-5%.

[0022] Thus, when the above oxygen content and nitrogen content are maintained within the above ranges, it can not only promote the formation of a stable carbon layer structure in the negative electrode material, but also make the carbon microcrystalline structure closely connected and there is no obvious pore structure. Thus, the conductivity of the negative electrode material is effectively improved.

[0023] In an implementable manner, the specific surface area of the negative electrode material is 0.5 m 2 / g - 10 m 2 / g.

[0024] Thus, the negative electrode material provided by the embodiments of the present application has a high specific surface area, which can improve the first Coulombic efficiency of the sodium-ion battery. Furthermore, the performance of the sodium-ion battery is improved.

[0025] In an implementable manner, the carbon microcrystalline structure further includes sp 3 hybridized carbon, and the mass percentage of sp 3 hybridized carbon in the carbon microcrystalline structure is 42%-60%.

[0026] Thus, in addition to including sp 2 hybridized carbon, the carbon microcrystalline structure can also include sp 3 hybridized carbon. The sp 3 hybridized carbon can ensure that there is a certain spatial stacking structure in the negative electrode material, which is beneficial to the insertion and extraction of sodium ions and can improve the conductivity of the negative electrode material. Thus, the conductivity of the negative electrode sheet in the sodium-ion battery can be improved, and to a certain extent, the rapid diffusion of sodium ions is promoted.

[0027] Second, the embodiments of the present application provide a preparation method of a negative electrode material. The method includes: mixing an initiator and a reaction monomer evenly and performing a polycondensation reaction to obtain a precursor material. The precursor material can also be carbonized and ground to obtain a negative electrode material. Among them, the negative electrode material includes a carbon microcrystalline structure, and the carbon microcrystalline structure includes sp 2 hybridized carbon, and the mass percentage of sp 2 hybridized carbon in the carbon microcrystalline structure is 40%-58%.

[0028] Thus, the negative electrode material prepared by the above method in the embodiments of the present application includes sp 2 hybridized carbon, sp 2The hybrid carbon belongs to a planar structure, which can enable a better ordered stacking planar structure in the carbon microcrystal structure. Thus, the conductivity of the negative electrode material can be improved. Furthermore, the conductivity of the negative electrode sheet in the sodium-ion battery can be improved, and to a certain extent, the rapid diffusion of sodium ions is promoted, and the current performance of the sodium-ion battery is improved.

[0029] In one feasible way, the initiator includes at least one of benzoyl peroxide, dicumyl peroxide, diisopropyl peroxydicarbonate, hexamethylenetetramine, azobisisobutyronitrile, 1-methylpyridine, 2,4-dimethylpyridine, pyrrole, triethylamine, tripropylamine, tri-n-butylamine, and indole. The reaction monomers include at least two of ethylene tar, olefin monomers, and diolefin monomers.

[0030] In one feasible way, the reaction temperature of the polycondensation reaction is 100°C - 300°C, and the reaction time is 2h - 8h.

[0031] Thus, by controlling the reaction temperature and reaction time of the polycondensation reaction in the embodiments of the present application, the polycondensation reaction effect can be better, and the controllability during the preparation process is higher, so that a negative electrode material with high conductivity can be prepared.

[0032] In one feasible way, the precursor material is carbonized and ground to obtain the negative electrode material, including: the precursor material can be carbonized under an inert atmosphere; wherein, the carbonization treatment temperature is 1000°C - 1600°C, the carbonization heating rate is 0.5°C / min - 5°C / min, and the carbonization treatment time is 2h - 10h. The carbonized precursor material can also be ground to obtain the negative electrode material.

[0033] Thus, by carbonizing and grinding the precursor material under the above conditions in the embodiments of the present application, the carbonization process effect can be better, and the negative electrode material can be obtained. The negative electrode material has a better flat layer stacking structure, so that the conductivity of the negative electrode material can be improved.

[0034] In one feasible way, the molar ratio of the initiator to the reaction monomer is (1 - 10):1.

[0035] Thus, by controlling the contents of the initiator and the reaction monomer within a certain range in the embodiments of the present application, the polycondensation reaction effect can be better, so that a negative electrode material with high conductivity can be prepared.

[0036] In a third aspect, the embodiments of the present application provide a negative electrode sheet, which includes a negative electrode current collector and a negative electrode material layer disposed on at least one side of the negative electrode current collector. The negative electrode material layer includes the negative electrode material as described in the first aspect or the negative electrode material prepared by the preparation method as described in the second aspect.

[0037] In a fourth aspect, an embodiment of the present application provides a sodium-ion battery, which includes a positive electrode sheet, a negative electrode sheet, a separator located between the positive electrode sheet and the negative electrode sheet, and an electrolyte. The electrolyte is filled between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet includes the negative electrode material as described in the first aspect or the negative electrode material prepared by the preparation method as described in the second aspect.

[0038] In a fifth aspect, an embodiment of the present application provides an electronic device, which includes a housing, electronic components and a battery housed in the housing. The battery powers the electronic components, and the battery includes the sodium-ion battery as described in the fourth aspect above. Description of the Drawings

[0039] Figure 1 is a schematic structural diagram of a sodium-ion battery provided by an embodiment of the present application;

[0040] Figure 2 is a schematic structural diagram of a negative electrode material provided by an embodiment of the present application;

[0041] Figure 3 is a schematic process diagram of preparing a negative electrode material provided by an embodiment of the present application. Detailed Embodiments

[0042] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application. Among them, in the description of the present application, unless otherwise specified, " / " means that the objects associated before and after are in an "or" relationship. For example, A / B may represent A or B. The "and / or" in the present application is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. These three situations, where A and B can be singular or plural. And, in the description of the present application, unless otherwise specified, "a plurality" means two or more than two. "At least one (item)" or its similar expression below refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b, or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, c can be single or multiple. In addition, in order to clearly describe the technical solutions in the embodiments of the present application, in the embodiments of the present application, terms such as "first" and "second" are used to distinguish the same items or similar items with basically the same functions and roles.

[0043] Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity and execution order, and the terms "first", "second", etc. do not necessarily limit being different. At the same time, in some embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner for easy understanding.

[0044] For ease of understanding, some explanations of concepts related to the embodiments of the present application are given as examples for reference. As follows:

[0045] Cathode: In a primary battery, the electrode with a higher electrode potential where the current flows out is the cathode, which gains electrons and undergoes reduction. In an electrolytic cell, the positive electrode is the electrode connected to the positive pole of the power supply, which loses electrons and undergoes oxidation.

[0046] Anode: In a primary battery, the electrode with a lower electrode potential where the current flows in is the anode, which loses electrons and undergoes oxidation. In an electrolytic cell, the negative electrode is the electrode connected to the negative pole of the power supply, which gains electrons and undergoes reduction.

[0047] Electrolyte: Provides a medium for ion exchange between the positive and negative electrodes of the battery.

[0048] Separator: The main function of the separator is to separate the positive and negative electrodes of the battery to prevent short - circuit due to contact between the two poles. In addition, it also has the function of allowing electrolyte ions to pass through.

[0049] Film - forming additive: It is a kind of substance that decomposes preferentially on the material surface to form an interfacial film prior to organic solvents, and can significantly improve the battery performance.

[0050] d002 layer spacing: It refers to the distance between the layered structures in the material.

[0051] sp 2 -type carbon: sp 2 Hybrid - type carbon, where carbon atoms are composed of 3 s - type orbitals and 1 p - type orbital. Each orbital can accommodate 2 electrons, and the hybridization shape of carbon atoms is dihedral.

[0052] sp 3 -type carbon: sp 3 Hybrid - type carbon, where carbon atoms are composed of 4 s - type orbitals and 1 p - type orbital. Each orbital can accommodate 2 electrons, and the hybridization shape of carbon atoms is regular tetrahedral.

[0053] Generally, carbonaceous anode materials are composed of a large amount of amorphous carbon and graphene nanosheets with obvious turbulent disorder and curvature. Thus, the carbon microstructure of the carbonaceous anode material presents a relatively disordered structure, which will affect the internal electron transport channels of the material and reduce the conductivity of the material.

[0054] In the related art, an anode material is provided. The anode material includes a porous carbon layer, and a number of micropores are provided inside the porous carbon layer, and carbon microcrystals of graphite-like layers are filled inside the micropores. However, the conductivity of the porous carbon is low, and even if it is provided with micropores and filled with carbon microcrystals of graphite-like layers, its conductivity cannot be improved to a certain extent. At the same time, the material structure of the anode material is divided into two parts, its technical process is complex, and the preparation controllability during the filling process is poor.

[0055] In the related art, an anode material is also provided. The anode material is prepared by drying waste biomass and then carbonizing and cracking it. Among them, the obtained anode material is irregular blocky particles. However, the carbon microstructure of the anode material presents a more disordered structure, which will affect the internal electron transport channels of the material and reduce the rate performance and conductivity of the material.

[0056] To solve the above problems, the embodiments of the present application provide an anode material, a sodium-ion battery and an electronic device. Among them, the anode material can be used to prepare the negative electrode sheet of a sodium-ion battery. The anode material proposed by the embodiments of the present application includes a carbon microcrystal structure formed by stacking multiple carbon layers. The carbon microcrystal structure includes sp 2 hybridized carbon, and the mass percentage of sp 2 hybridized carbon in the carbon microcrystal structure is 40%-58%.

[0057] On the one hand, the anode material includes a carbon microcrystal structure, and the carbon microcrystal structure includes sp 2 hybridized carbon. The sp 2 hybridized carbon belongs to a planar structure and can form a layered structure. This can enable the formed carbon layer to have a good flat-layer stacking structure, and further enable the carbon microcrystal structure to have a good ordered stacking planar structure. Thus, the conductivity of the anode material can be improved. Furthermore, the conductivity of the negative electrode sheet in the sodium-ion battery can be improved, and to a certain extent, the rapid diffusion of sodium ions is promoted, and the current performance of the sodium-ion battery is improved.

[0058] On the other hand, the embodiments of the present application can regulate the content of sp 2 hybridized carbon, which can enable the carbon layer structures to have a good and ordered layered structure, and further ensure a good size of the carbon microcrystal structure. Thus, the conductivity and tap density of the anode material can be further improved. Furthermore, the electrochemical sodium storage capacity of the anode material is improved.

[0059] An embodiment of the present application also provides a sodium-ion battery. Figure 1 It is a schematic structural diagram of the sodium-ion battery provided by the embodiment of the present application. As Figure 1 shown, the sodium-ion battery includes a positive electrode sheet 10, a negative electrode sheet 20, a separator 30, and an electrolyte 40. Among them, the separator 30 is disposed between the positive electrode sheet 10 and the negative electrode sheet 20, and the electrolyte 40 is filled between the positive electrode sheet 10 and the negative electrode sheet 20 and wets the separator 30. During charging, sodium ions are released from the positive electrode material 102 of the positive electrode sheet 10, and after passing through the electrolyte 40, they are embedded into the negative electrode material 202 of the negative electrode sheet 20; during discharging, sodium ions are released from the negative electrode material 202, and after passing through the electrolyte 40, they are inserted into the positive electrode material 102.

[0060] Continuing to refer to Figure 1 , in the sodium-ion battery provided by the embodiment of the present application, the separator 30 blocks the passage of electrons and allows ions to pass through. The separator 30 includes, but is not limited to, single-layer polypropylene (PP), single-layer polyethylene (PE), double-layer PP / PE, double-layer PP / PP, triple-layer PP / PE / PP, and ceramic-coated PE, etc. In the sodium-ion battery, the electrolyte 40 is a transmission medium for sodium ions during transmission between the positive electrode sheet 10 and the negative electrode sheet 20.

[0061] As Figure 1 shown, the positive electrode sheet 10 includes a positive electrode current collector 101 and a positive electrode material layer coated on the surface of the positive electrode current collector 101. In addition to the positive electrode material 102, the positive electrode material layer may also include a certain amount of binder, conductive agent, and other components.

[0062] Among them, the positive electrode current collector 101 can be a metal foil, such as aluminum foil, gold foil, platinum foil, etc. The positive electrode material 102 can reversibly insert / extract sodium ions. The positive electrode material 102 includes, but is not limited to, at least one of layered sodium transition metal oxides, Prussian white compounds, Prussian blue compounds, and sodium polyanion-type compounds.

[0063] Sodium transition metal oxides such as sodium nickel iron manganese (NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, NFM111), Prussian white compounds such as (Na2Mn[Fe(CN)6], PBA), Prussian blue compounds such as (NaMn[Fe(CN)6], PBA), sodium polyanion-type compounds such as sodium iron phosphate (NaFePO4, NFP), sodium iron sulfate (Na2Fe 2((SO4)3, NFS). The binder can be, for example, polyvinylidene fluoride (poly1,1-difluoroethylene, PVDF), and the conductive agent can be, for example, conductive carbon black (super P), graphite, amorphous carbon, carbon nanotubes, carbon fibers, graphene, etc. The positive current collector 101, the positive electrode material 102, the binder, and the conductive agent used for preparing the positive electrode sheet 10 are only for illustrative purposes, and the embodiments of the present application are not limited thereto. Taking the positive electrode material 102 as an example, theoretically, it can be a compound that can reversibly intercalate / deintercalate sodium ions.

[0064] Continuing to refer to Figure 1 In the sodium-ion battery provided by the embodiment of the present application, the negative electrode sheet 20 includes a negative current collector 201 and a negative electrode material layer coated on the surface of the negative current collector. In addition to the negative electrode material 202, the negative electrode material layer may also include a certain amount of binder, conductive agent and other components. Among them, the negative current collector 201 can be a metal foil, such as copper foil, aluminum foil, gold foil, platinum foil, etc. The conductive agent can be, for example, acetylene black, graphite, amorphous carbon, etc. It should be noted that the negative current collector 201, the binder, and the conductive agent used for preparing the negative electrode sheet 20 are only for illustrative purposes, and the embodiments of the present application are not limited thereto.

[0065] In an embodiment of the present application, the negative electrode material 202 may include a carbon microcrystalline structure, and the carbon microcrystalline structure includes sp 2 hybridized carbon, sp 2 The mass percentage of the hybridized carbon in the carbon microcrystalline structure is 40%-58%. The embodiments of the present application do not specifically limit it.

[0066] As an illustrative example, the mass percentage of the above-mentioned sp 2 hybridized carbon in the carbon microcrystalline structure is 40%-58%. The value of this ratio is typical but non-limiting. For example, it can be 40%, 45%, 50%, 55%, 58%, and the numbers between any two of the above values are all within the acceptable range. For example, the ratio can be taken from the values between 40%-42%, or from the values between 42%-55%, or from the values between 55%-58%, or other values between any two other numbers.

[0067] Specifically, in the embodiment of the present application, the morphology of the obtained sample is characterized by scanning electron microscopy and transmission electron microscopy. Refer to Figure 2 (A) in, the carbon microcrystalline structure in the negative electrode material presents an obvious irregular block structure morphology. It can be seen from the test structure of the transmission electron microscope that the microstructure of the negative electrode material presents an obvious amorphous state, the carbon microcrystalline structures are closely connected, and there is no obvious pore structure, indicating that the negative electrode material can mainly store sodium by interlayer.

[0068] Refer toFigure 2 In (B), the carbon microcrystalline structure has a certain stacked layered structure, and there is a certain interlayer spacing between the carbon layers, which is conducive to the embedding and extraction of sodium ions.

[0069] In some embodiments of the present application, sp 2 The mass percentage of hybrid carbon in the carbon microcrystalline structure is 50%-58%.

[0070] In the implementation of this application, the sp 2 The proportion of hybrid carbon in the carbon microcrystalline structure is between 40% and 58%, and more preferably between 50% and 58%.

[0071] As an example, the above sp 2 The mass percentage of hybrid carbon in the carbon microcrystalline structure is 50%-58%. The value of this numerical ratio can be typically but not limitedly, for example, 50%, 51%, 53%, 54%, 58% and numbers between any two of the above values, all of which are acceptable range values, for example, the numerical ratio can be taken from a value between 50%-52%, a value between 52%-54%, a value between 54%-58%, or a value between any two other values.

[0072] Thus, the carbon microstructure includes sp 2 Hybrid carbon, sp 2 Hybridized carbon has a planar structure, which is conducive to the embedding and extraction of sodium ions, and can improve the conductivity of negative electrode materials. Therefore, it can improve the conductivity of the negative electrode sheet in the sodium ion battery and promote the rapid diffusion of sodium ions to a certain extent. In turn, it improves the current performance of the sodium ion battery.

[0073] In addition, the present application embodiment can be used for sp 2 The content of hybrid carbon is further regulated to induce the short-range ordered arrangement of the carbon microcrystalline structure, ensuring a better flat layer stacking structure and carbon microcrystalline structure size in the negative electrode material. On the basis of ensuring the sodium deintercalation capacity of the negative electrode material, the high compaction density and high electrochemical sodium storage capacity characteristics of the negative electrode material are achieved, which can effectively improve the energy density of sodium-ion batteries.

[0074] In some embodiments of the present application, the carbon microcrystalline structure includes a plurality of stacked carbon layers, and the interlayer spacing between the plurality of carbon layers is 0.35 nm-0.38 nm.

[0075] As an exemplary illustration, in the embodiments of the present application, the interlayer spacing between multiple carbon layers can be measured by X-ray diffraction to be 0.35 nm - 0.38 nm. The values of this numerical range are typical but non-limiting, for example, they can be 0.35 nm, 0.365 nm, 0.37 nm, 0.375 nm, 0.38 nm, and the numbers between any two of the above values, all of which are within the acceptable range. For example, the value can be taken from the range between 0.35 nm and 0.36 nm, or from the range between 0.36 nm and 0.37 nm, or from the range between 0.37 nm and 0.38 nm, or from the numbers between any other two values.

[0076] Thus, the interlayer spacing d002 between multiple carbon layers provided by the embodiments of the present application is 0.35 nm - 0.38 nm. The distance between multiple layered structures is small, which can improve the conductivity and tap density of the negative electrode material. Furthermore, the electrochemical performance of the sodium-ion battery is ensured.

[0077] In some embodiments of the present application, the length (La) of the carbon microcrystalline structure is 2 nm - 5.5 nm.

[0078] As an exemplary illustration, in the embodiments of the present application, the length of the carbon microcrystalline structure can be measured by X-ray diffraction to be 2 nm - 5.5 nm. The values of this numerical range are typical but non-limiting, for example, they can be 2 nm, 3 nm, 4 nm, 5 nm, 5.5 nm, and the numbers between any two of the above values, all of which are within the acceptable range. For example, the value can be taken from the range between 2 nm and 3 nm, or from the range between 3 nm and 4 nm, or from the range between 4 nm and 5.5 nm, or from the numbers between any other two values.

[0079] Thus, the carbon microcrystalline structure in the embodiments of the present application has a more suitable size, which enables it to have a higher conductivity while taking into account the efficient storage of sodium ions.

[0080] In some embodiments of the present application, the number of carbon layers n is: 2 ≤ n ≤ 5.

[0081] As an exemplary illustration, the number of the above carbon layers n is: 2 ≤ n ≤ 5. The values of this numerical range are typical but non-limiting, for example, they can be 2, 3, 4, 5, and the numbers between any two of the above values, all of which are within the acceptable range.

[0082] Thus, the carbon microcrystalline structure in the embodiments of the present application has a certain number of carbon layers, which can maintain a more suitable flat-layer stacking structure, enabling it to have a higher conductivity and improving the conductivity of the negative electrode material. Furthermore, the conductivity of the negative electrode plate in the sodium-ion battery can be improved.

[0083] In some embodiments of the present application, the conductivity of the negative electrode material is 50 S / cm - 80 S / cm.

[0084] As an exemplary illustration, in the embodiments of the present application, the conductivity of the negative electrode material can be measured to be 50 S / cm - 80 S / cm by a four-probe test instrument under a test pressure of 25 Mpa. The values of this numerical ratio are typical but non-limiting. For example, they can be 50 S / cm, 60 S / cm, 70 S / cm, 80 S / cm, and the numbers between any two of the above values, all of which are within the acceptable range. For example, the numerical ratio can be taken from the values between 50 S / cm - 60 S / cm, or from the values between 60 S / cm - 70 S / cm, or from the values between 70 S / cm - 80 S / cm, or it can also be taken from the numbers between any other two values.

[0085] Thus, the negative electrode material provided by the embodiments of the present application has a high conductivity, which can significantly improve the electron transport characteristics inside the negative electrode material and reduce the polarization of the negative electrode material. Furthermore, the electrochemical performance of the sodium-ion battery is improved.

[0086] In some embodiments of the present application, the tap density of the negative electrode material is 0.95 g / cm 3 -1.1 g / cm 3 .

[0087] As an exemplary illustration, in the embodiments of the present application, the tap density of the negative electrode material can be measured to be 0.95 g / cm 3 -1.1 g / cm 3 by a tap density meter under a pressure of 5 T. The values of this numerical ratio are typical but non-limiting. For example, they can be 0.95 g / cm 3 , 0.98 g / cm 3 , 0.99 g / cm 3 , 1.1 g / cm 3 and the numbers between any two of the above values, all of which are within the acceptable range. For example, the numerical ratio can be taken from the values between 0.95 g / cm 3 -0.98 g / cm 3 , or from the values between 0.98 g / cm 3 -1.0 g / cm 3 , or from the values between 1.0 g / cm 3 -1.1 g / cm 3 , or it can also be taken from the numbers between any other two values.

[0088] Thus, the negative electrode material provided by the embodiments of the present application has a high tap density, which can improve the volumetric energy density of the sodium-ion battery.

[0089] In some embodiments of the present application, the oxygen content of the negative electrode material is 0.5% - 5%, and the nitrogen content is 0.5% - 5%.

[0090] Thus, maintaining the above oxygen and nitrogen contents within the above ranges can not only promote the formation of a stable carbon layer structure in the negative electrode material, but also make the carbon microcrystal structure closely connected with no obvious pore structure. As a result, the conductivity of the negative electrode material is effectively improved.

[0091] As an illustrative example, in the embodiments of the present application, an oxygen and nitrogen tester can be used to measure that the oxygen content of the negative electrode material is 0.5% - 5%. The values of this ratio are exemplary but non-limiting, and can be, for example, 0.5%, 1.5%, 2.5%, 5%, and numbers between any two of the above values, all of which are within the acceptable range. For example, the ratio can be taken from the values between 0.5% - 1.5%, or from the values between 1.5% - 3%, or from the values between 3% - 5%, or from any other two values.

[0092] In addition, it is measured that the nitrogen content of the negative electrode material is 0.5% - 5%. The values of this ratio are exemplary but non-limiting, and can be, for example, 0.5%, 1.5%, 2.5%, 5%, and numbers between any two of the above values, all of which are within the acceptable range. For example, the ratio can be taken from the values between 0.5% - 1.5%, or from the values between 1.5% - 3%, or from the values between 3% - 5%, or from any other two values.

[0093] In some embodiments of the present application, the specific surface area of the negative electrode material is 0.5 m 2 / g - 10 m 2 / g.

[0094] As an illustrative example, in the embodiments of the present application, a specific surface area tester can be used to measure that the specific surface area of the negative electrode material is 0.5 m 2 / g - 10 m 2 / g. The values of this ratio are exemplary but non-limiting, and can be, for example, 0.5 m 2 / g, 0.6 m 2 / g, 5 m 2 / g, 8 m 2 / g, 10 m 2 / g, and numbers between any two of the above values, all of which are within the acceptable range. For example, the ratio can be taken from the values between 0.5 m 2 / g - 3 m 2 / g, or from the values between 3 m 2 / g - 4 m 2 / g, or from the values between 4 m 2 / g - 10 m 2 / g, or from any other two values.

[0095] Thus, the negative electrode material provided by the embodiments of the present application has a high specific surface area, which can improve the first Coulomb efficiency of the sodium-ion battery. Furthermore, the performance of the sodium-ion battery is improved.

[0096] In some embodiments of the present application, the carbon microcrystalline structure further includes sp 3 hybridized carbon, and the mass percentage of the sp 3 hybridized carbon in the carbon microcrystalline structure is 42%-60%.

[0097] As an illustrative example, the mass percentage of the above-mentioned sp 3 hybridized carbon in the carbon microcrystalline structure is 42%-60%. The value of this ratio is typical but not restrictive. For example, it can be 42%, 51%, 53%, 54%, 60% and the numbers between any two of the above values, all of which are acceptable range values. For example, the ratio can be taken from the values between 42%-52%, or from the values between 52%-54%, or from the values between 54%-60%, or it can also take other numbers between any two values.

[0098] Thus, in addition to the sp 2 hybridized carbon, the carbon microcrystalline structure may further include sp 3 hybridized carbon. The sp 3 hybridized carbon can ensure that there is a certain spatial stacking structure in the negative electrode material, which is beneficial to the insertion and extraction of sodium ions, and can improve the conductivity of the negative electrode material. Therefore, the conductivity of the negative electrode sheet in the sodium-ion battery can be improved, and to a certain extent, the rapid diffusion of sodium ions is promoted.

[0099] The embodiments of the present application also provide a preparation method of a negative electrode material. Refer to Figure 3 , which includes the following steps:

[0100] S301. Mix the initiator and the reaction monomer evenly and carry out a polycondensation reaction to obtain a precursor material.

[0101] In some embodiments of the present application, the precursor can be prepared first. Specifically, the reaction monomer is added to the reaction kettle, initiators with different electronegativities are added respectively, and stirred evenly at room temperature to ensure that the reaction monomer and the initiator molecules are evenly mixed. Then, the mixed reaction monomer and initiator are subjected to a polycondensation reaction. After cooling to room temperature, a precursor material is obtained. Among them, the reaction temperature of the polycondensation reaction is 100°C-300°C, and the reaction time is 2h-8h.

[0102] As an illustrative example, the reaction temperature of the above-mentioned polycondensation reaction is 100°C-300°C. Specifically, it can be 100°C, 300°C and any value between 100°C-300°C, such as 110°C, 120°C, 150°C, 259°C, etc. They are not listed one by one here.

[0103] The above carbonization treatment time is 2h - 8h. Specifically, it can be 2h, 8h, and any value between 2h - 8h, such as 2.5h, 3h, 4h, 6h, etc. They are not listed one by one here.

[0104] In some embodiments of the present application, the initiator may include an oxygen - containing or nitrogen - containing initiator, and this initiator may have different electronegativities. Exemplarily, the initiator may include at least one of benzoyl peroxide, dicumyl peroxide, di - isopropyl peroxydicarbonate, hexamethylenetetramine, azobisisobutyronitrile, 1 - methylpyridine, 2,4 - dimethylpyridine, pyrrole, triethylamine, tripropylamine, tri - n - butylamine, and indole.

[0105] In some embodiments of the present application, the reaction monomer may be a reaction monomer with a carbon - carbon double bond. Exemplarily, the reaction monomer may include at least two of vinyl tar, olefin monomers, and diene monomers.

[0106] It should be noted that the above initiators and reaction monomers are only for exemplary illustration. The embodiments of the present application do not limit the specific implementation manners of the initiators and reaction monomers.

[0107] In some embodiments of the present application, the molar ratio of the initiator to the reaction monomer is (1 - 10):1.

[0108] As an exemplary illustration, the molar ratio of the above initiator to the reaction monomer is (1 - 10):1. The values of this numerical ratio are typical but non - restrictive. For example, it can be 1:1, 2:1, 2.5:1, 3:1, 4.5:1, 8:1, and the numbers between any two of the above values are all within the acceptable range. For example, the numerical ratio can be taken from the values between 1:1 and 2:1, or from the values between 2:1 and 8:1, or from the values between 8:1 and 10:1, or it can also take other numbers between any two values.

[0109] It can be seen from the above that the embodiments of the present application can regulate the molar ratio between the initiator and the reaction monomer, making the contents of the initiator and the reaction monomer more appropriate, so that the two can fully carry out the polymerization reaction. Furthermore, it can subsequently form a negative electrode material with high conductivity.

[0110] S302. Carbonize and grind the precursor material to obtain the negative electrode material.

[0111] In some embodiments of the present application, the obtained precursor material can be subjected to high-temperature forming. Specifically, the precursor material can be subjected to high-temperature carbonization treatment in an inert atmosphere and its temperature can be naturally cooled to room temperature. Among them, the carbonization treatment temperature is 1000°C - 1600°C, the carbonization heating rate is 0.5°C / min - 5°C / min, and the carbonization treatment time is 2h - 10h. Then, the precursor material that has been carbonized and cooled to room temperature can be ground to obtain the negative electrode material. Among them, this negative electrode material is the negative electrode material described above and will not be elaborated here.

[0112] As an exemplary illustration, the above carbonization treatment temperature is 1000°C - 1600°C. Specifically, it can be 1000°C, 1600°C, and any value between 1000°C - 1600°C, such as 1100°C, 1200°C, 1500°C, 1590°C, etc. They are not listed one by one here.

[0113] The above carbonization heating rate is 0.5°C / min - 5°C / min. Specifically, it can be 0.5°C / min, 5°C / min, and any value between 0.5°C / min - 5°C / min, such as 0.6°C / min, 2.8°C / min, 3.9°C / min, 4.8°C / min, etc. They are not listed one by one here.

[0114] The above carbonization treatment time is 2h - 10h. Specifically, it can be 2h, 10h, and any value between 2h - 10h, such as 2.5h, 3h, 4h, 6h, etc. They are not listed one by one here.

[0115] It can be understood that for the calculated values of the above numerical ratios, in actual test operations, a certain measurement test system error is allowed to exist, and the values within the system error range can be understood as the range defined by the embodiments of the present application.

[0116] In some embodiments of the present application, during the process of grinding the precursor material, the grinding methods that can be adopted include jet mill, mechanical mill, roller press mill, ball mill, etc. The embodiments of the present application do not specifically limit the grinding method.

[0117] The above negative electrode material is introduced below through specific embodiments.

[0118] Example 1

[0119] S10. Add vinyl tar and hexamethylenetetramine into a reaction kettle and mix them into a homogeneous and stable solution, and the molar ratio of the two is 1:4. Subsequently, seal it in the reaction kettle and place it at 200°C for 6h for polycondensation reaction to obtain the precursor material.

[0120] S11. Burn the precursor material in an argon atmosphere. The carbonization temperature is 1200 °C, and the carbonization time is 3 h. Then, crush the burned precursor material in a jet mill to D50 of 5.0 microns to obtain the negative electrode material.

[0121] Example 2

[0122] S20. Add vinyl tar and hexamethylenetetramine to a reaction kettle and mix them into a homogeneous and stable solution. The molar ratio of the two is 1:3. Then, seal it in the reaction kettle and react at 200 °C for 6 h for a polycondensation reaction to obtain the precursor material.

[0123] S21. Burn the precursor material in an argon atmosphere. The carbonization temperature is 1200 °C, and the carbonization time is 3 h. Then, crush the burned precursor material in a jet mill to D50 of 5.0 microns to obtain the negative electrode material.

[0124] Example 3

[0125] S30. Add vinyl tar and hexamethylenetetramine to a reaction kettle and mix them into a homogeneous and stable solution. The molar ratio of the two is 1:4. Then, seal it in the reaction kettle and react at 100 °C for 6 h for a polycondensation reaction to obtain the precursor material.

[0126] S31. Burn the precursor material in an argon atmosphere. The carbonization temperature is 1200 °C, and the carbonization time is 3 h. Then, crush the burned precursor material in a jet mill to D50 of 5.0 microns to obtain the negative electrode material.

[0127] Example 4

[0128] S40. Add vinyl tar and hexamethylenetetramine to a reaction kettle and mix them into a homogeneous and stable solution. The molar ratio of the two is 1:4. Then, seal it in the reaction kettle and react at 200 °C for 6 h for a polycondensation reaction to obtain the precursor material.

[0129] S41. Burn the precursor material in an argon atmosphere. The carbonization temperature is 1500 °C, and the carbonization time is 3 h. Then, crush the burned precursor material in a jet mill to D50 of 5.0 microns to obtain the negative electrode material.

[0130] Example 5

[0131] S50. Add vinyl tar and benzoyl peroxide to a reaction kettle and mix them into a homogeneous and stable solution. The molar ratio of the two is 1:4. Then, seal it in the reaction kettle and react at 200 °C for 6 h for a polycondensation reaction to obtain the precursor material.

[0132] S51. The precursor material is fired in an argon atmosphere at a carbonization temperature of 1200 °C for 3 h. Then, the fired precursor material is crushed in a jet mill to a D50 of 5.0 μm to obtain the anode material.

[0133] Example 6

[0134] S60. Ethylene tar and 1-methylpyridine are added to a reaction kettle and mixed into a homogeneous and stable solution with a molar ratio of 1:4. Subsequently, it is placed in the sealed reaction kettle and reacted at 200 °C for 6 h for a polycondensation reaction to obtain the precursor material.

[0135] S61. The precursor material is fired in an argon atmosphere at a carbonization temperature of 1200 °C for 3 h. Then, the fired precursor material is crushed in a jet mill to a D50 of 5.0 μm to obtain the anode material.

[0136] Comparative Example 1

[0137] S70. Ethylene tar is added to a reaction kettle and placed in the sealed reaction kettle and reacted at 200 °C for 6 h for a polycondensation reaction to obtain the precursor material.

[0138] S71. The precursor material is fired in an argon atmosphere at a carbonization temperature of 1200 °C for 3 h. Then, the fired precursor material is crushed in a jet mill to a D50 of 5.0 μm to obtain the anode material.

[0139] Comparative Example 2

[0140] S80. The coconut shell is subjected to raw material treatment and pre-carbonized at 500 °C for 6 h to obtain the precursor material.

[0141] S81. The precursor material is pickled to remove impurities, crushed, and fired at a carbonization temperature of 1400 °C for 3 h. Then, the fired precursor material is sieved and demagnetized to a D50 of 5.0 μm to obtain the anode material.

[0142] Comparative Example 3

[0143] S90. The phenolic resin material is cured as a raw material and pre-carbonized at 500 °C for 6 h to obtain the precursor material.

[0144] S91. The precursor material is crushed and fired at a carbonization temperature of 1400 °C for 3 h. Then, the fired precursor material is sieved and demagnetized to a D50 of 5.0 μm to obtain the anode material.

[0145] Comparative Example 4

[0146] S100. Treat anthracite as the raw material, and pre-carbonize it at 500 °C for 6 h to obtain the precursor material.

[0147] S110. Pickle, crush and calcine the precursor material. The carbonization temperature is 1400 °C and the carbonization time is 3 h. Then, screen and demagnetize the calcined precursor material until D50 reaches 5.0 microns to obtain the anode material.

[0148] Perform performance tests on the anode materials prepared in the above Examples 1-6 and Comparative Examples 1-4, as well as the corresponding sodium-ion batteries. The test results are as follows:

[0149] In some embodiments of the present application, for the technical characterizations in terms of layer spacing, sp 2 hybridized carbon ratio, oxygen and nitrogen content analysis, crystallite length, crystallite layer number, specific surface area, etc., as shown in Table 1 below. It can be seen that Comparative Example 1 is a sample prepared from a polymer monomer without an initiator, and Comparative Example 4 is prepared from anthracite material through steps such as high-temperature carbonization and crushing. It can be found that the layer spacing of Comparative Example 1 and Comparative Example 4 is relatively small, and the sp 2 hybridized carbon ratio is relatively high, and the crystallite length and layer number are also relatively high. The flat-layer stacking phenomenon is serious, and the carbon crystallite structure size is relatively large, which is not conducive to the insertion and extraction of sodium ions and cannot effectively regulate the microstructure of the anode material. As a result, the electrochemical sodium storage capacity of the anode material is relatively low.

[0150] Comparative Example 2 and Comparative Example 3 are respectively prepared from biomass raw materials and resins through steps such as high-temperature carbonization and crushing, and their raw material controllability is poor. It can be found that the layer spacing of Comparative Example 1 and Comparative Example 4 is relatively high, the sp 2 hybridized carbon ratio is relatively low, and the sp 2 hybridized carbon ratio is relatively high. The space stacking phenomenon is serious, which seriously affects the electrical conductivity and overall compaction density of the anode material, and also cannot effectively regulate the microstructure of the anode material. Thus, it affects the performance of the anode material.

[0151] In addition, Examples 1-5 are samples prepared from polymer monomers with initiators. Their layer spacing, sp 2 hybridized carbon ratio, oxygen and nitrogen content, crystallite length and layer number are all maintained within a suitable range. This ensures a better flat-layer stacking phenomenon and carbon crystallite structure size in the anode material. It can further improve the electrical conductivity and compaction density of the anode material. Thus, the electrochemical sodium storage capacity of the anode material is increased.

[0152] Table 1

[0153]

[0154] In some embodiments of the present application, in order to characterize the role of the material in improving the sodium electrochemical performance, we characterized the coin cell test capacity, Coulomb efficiency, powder compaction, powder conductivity, etc. of the material, as shown in Table 2 below.

[0155] It can be seen that the mass specific capacity and compaction density corresponding to Comparative Examples 1-4 are both low, which reduces the volume specific capacity of the negative electrode material and cannot improve the energy density of the battery. At the same time, the powder conductivity corresponding to Comparative Examples 1 and 4 is high and the first Coulomb efficiency is low. The powder conductivity corresponding to Comparative Examples 2 and 3 is low and the first Coulomb efficiency is high. It is impossible to balance the conductivity and cycle performance of the negative electrode material.

[0156] In addition, the mass specific capacity and compaction density corresponding to Examples 1-5 are both high. On the basis of ensuring the sodium storage capacity of the negative electrode material, the volume specific capacity (mass specific capacity × compaction density) of the negative electrode material can be effectively improved, thereby improving the energy density of the battery. At the same time, the powder conductivity and the first Coulomb efficiency of the negative electrode material are further improved, effectively improving the battery polarization and the electrochemical performance of the battery.

[0157] Table 2

[0158]

[0159] The embodiments of the present application provide a method for preparing a negative electrode material using a single molecular reaction monomer as the raw material and regulating the polymer structure based on a polymerization reaction. By exploring the structure-activity relationship between the proportion of sp 2 hybridized carbon in the negative electrode material and the sodium storage performance, the optimal parameter range of the proportion of sp 2 hybridized carbon with excellent sodium storage performance is determined to ensure the compaction density and electron transport characteristics of the negative electrode material, thereby improving the overall conductivity of the negative electrode material and reducing the polarization problem during the cycling of the battery cell.

[0160] The embodiments of the present application also provide a negative electrode plate, which includes a negative electrode current collector and a negative electrode material layer disposed on at least one side of the negative electrode current collector. The negative electrode material layer includes the above-mentioned negative electrode material or the negative electrode material prepared by the above-mentioned preparation method.

[0161] The embodiments of the present application also provide a sodium ion battery, which includes a positive electrode plate, a negative electrode plate, a separator located between the positive electrode plate and the negative electrode plate, and an electrolyte. The electrolyte is filled between the positive electrode plate and the negative electrode plate. The negative electrode plate includes the above-mentioned negative electrode material or the negative electrode material prepared by the above-mentioned preparation method.

[0162] An embodiment of the present application further provides an electronic device, which includes a housing, electronic components and a battery accommodated in the housing. The battery powers the electronic components, and the battery includes the sodium-ion battery described above.

[0163] The electronic device can be, for example, a mobile phone, a smart screen, a tablet computer, a personal computer (PC), a personal digital assistant (PDA), a smart watch, a mobile power supply, a netbook, a wearable device, an augmented reality (AR) device, a virtual reality (VR) device, a vehicle-mounted device, an energy storage device, a base station, an automobile, etc. The specific form of the electronic device in the embodiment of the present application is not particularly limited.

[0164] In some solutions, multiple embodiments of the present application can be combined and the combined solution can be implemented. Optionally, some operations in the processes of the method embodiments are optionally combined, and / or the order of some operations is optionally changed. Moreover, the execution order between the steps of each process is only exemplary and does not constitute a limitation on the execution order between the steps. The steps can also be in other execution orders. It is not intended to indicate that the execution order is the only order in which these operations can be performed.

[0165] Those of ordinary skill in the art will think of various ways to reorder the operations described in the embodiments of the present application. In addition, it should be noted that the process details involved in a certain embodiment of the present application are similarly applicable to other embodiments in a similar manner, or different embodiments can be combined and used.

[0166] In addition, some steps in the method embodiments can be equivalently replaced with other possible steps. Or, some steps in the method embodiments can be optional and can be deleted in some usage scenarios. Or, other possible steps can be added to the method embodiments. Moreover, the method embodiments can be implemented independently or in combination. The above content is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any change or replacement within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A negative electrode material, characterized in that, The negative electrode material includes a carbon microcrystalline structure, and the carbon microcrystalline structure includes sp 2 hybridized carbon, and the mass percentage of the sp 2 hybridized carbon in the carbon microcrystalline structure is 40%-58%.

2. The negative electrode material according to claim 1, characterized in that, The sp 2 The mass percentage of the hybridized carbon in the carbon microcrystalline structure is 50%-58%.

3. The negative electrode material according to claim 1 or 2, characterized in that The carbon microcrystalline structure includes a plurality of stacked carbon layers, and the interlayer spacing between the plurality of carbon layers is 0.35 nm - 0.38 nm.

4. The negative electrode material according to any one of claims 1 to 3, characterized in that The length of the carbon microcrystalline structure is 2 nm - 5.5 nm.

5. The negative electrode material according to claim 3, characterized in that, The number of layers n of the carbon layers is: 2 ≤ n ≤ 5.

6. The negative electrode material according to any one of claims 1-5, characterized in that, The conductivity of the negative electrode material is 50 S / cm - 80 S / cm.

7. The negative electrode material according to any one of claims 1-6, characterized in that, The tap density of the negative electrode material is 0.95 g / cm 3 -1.1 g / cm 3 .

8. The negative electrode material according to any one of claims 1-7, characterized in that, The oxygen content of the negative electrode material is 0.5% - 5%, and the nitrogen content of the negative electrode material is 0.5% - 5%.

9. The negative electrode material according to any one of claims 1-8, characterized in that, The specific surface area of the negative electrode material is 0.5 m 2 / g - 10 m 2 / g.

10. The negative electrode material according to any one of claims 1-9, characterized in that, The carbon microcrystalline structure further includes sp 3 hybridized carbon, and the mass percentage of the sp 3 hybridized carbon in the carbon microcrystalline structure is 42%-60%.

11. A method for preparing a negative electrode material, characterized in that, The method includes: Mixing an initiator and a reaction monomer uniformly and performing a polycondensation reaction to obtain a precursor material; Performing carbonization and grinding treatments on the precursor material to obtain a negative electrode material; Among them, the negative electrode material includes a carbon microcrystalline structure, and the carbon microcrystalline structure includes sp 2 hybridized carbon, and the mass percentage of the sp 2 hybridized carbon in the carbon microcrystalline structure is 40%-58%.

12. The method according to claim 11, wherein The initiator includes at least one of benzoyl peroxide, diisopropylbenzene peroxide, diisopropyl peroxydicarbonate, hexamethylenetetramine, azobisisobutyronitrile, 1-methylpyridine, 2,4-dimethylpyridine, pyrrole, triethylamine, tripropylamine, tri-n-butylamine, and indole; The reaction monomer includes at least two of vinyl tar, olefin monomers, and diolefin monomers.

13. The method according to claim 11 or 12, characterized in that, The reaction temperature of the polycondensation reaction is 100°C - 300°C, and the reaction time is 2 h - 8 h.

14. The method according to any one of claims 11 - 13, characterized in that The performing carbonization and grinding treatments on the precursor material to obtain a negative electrode material includes: Performing carbonization treatment on the precursor material in an inert atmosphere; wherein, the carbonization treatment temperature is 1000°C - 1600°C, the carbonization heating rate is 0.5°C / min - 5°C / min, and the carbonization treatment time is 2 h - 10 h; Performing grinding treatment on the precursor material after carbonization treatment to obtain a negative electrode material.

15. The method according to any one of claims 11-14, characterized in that, The molar ratio of the initiator to the reaction monomer is (1 - 10):

1.

16. A negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode material layer provided on at least one side of the negative electrode current collector, characterized in that, The negative electrode material layer includes the negative electrode material according to any one of claims 1 - 10 or the negative electrode material prepared by the preparation method according to any one of claims 11 - 15.

17. A sodium-ion battery, characterized in that, It includes a positive electrode plate, a negative electrode plate, a separator located between the positive electrode plate and the negative electrode plate, and an electrolyte. The electrolyte is filled between the positive electrode plate and the negative electrode plate, and the negative electrode plate includes the negative electrode material according to any one of claims 1 - 10 or the negative electrode material prepared by the preparation method according to any one of claims 11 - 15.

18. An electronic device, characterized in that, The electronic device includes a housing, and electronic components and a battery housed in the housing. The battery powers the electronic components, and the battery includes the sodium ion battery according to claim 17.

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