Negative electrode material, preparation method, negative electrode plate, sodium ion battery, and electronic device

Abstract

A negative electrode material, a preparation method, a negative electrode plate, a sodium ion battery, and an electronic device, relating to the technical field of batteries. The electrode material comprises carbonaceous particles, the carbonaceous particles comprising first amorphous carbon particles and second amorphous carbon particles, the first amorphous carbon particles having a blocky structure, and the second amorphous carbon particles having a spherical hard carbon structure. The Dv50 particle size of the second amorphous carbon particles is smaller than the Dv50 particle size of the first amorphous carbon particles, and the sphericity of the second amorphous carbon particles B is 0.7-1.0. The negative electrode material can improve compaction density while ensuring high sodium storage capacity.

Description

Negative electrode material and preparation method, negative electrode sheet, sodium ion battery and electronic device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on January 12, 2024, with application number 202410058157.3 and invention name “Negative electrode material and preparation method, negative electrode plate, sodium ion battery and electronic device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and more specifically, to negative electrode materials and preparation methods, negative electrode plates, sodium ion batteries, and electronic devices. Background Art

[0003] As my country gradually advances toward carbon peak and carbon neutrality, the development of large-scale energy storage technology is expected to become a trillion-dollar market in the future. Currently, electrochemical energy storage technology holds great promise for applications in large-scale energy storage demonstration projects and 5G base stations. However, energy storage systems based on lithium-ion batteries are relatively expensive, and the lithium battery industry currently faces severe resource constraints. Sodium-ion batteries, with their abundant raw material reserves, low cost, and high safety, are expected to replace lithium-ion batteries in large-scale energy storage.

[0004] As a crucial component of sodium-ion batteries, the performance of anode materials largely determines the battery's energy density and cycle life. Currently, the capacity of sodium-ion battery cathode materials is relatively low, making the full utilization of the anode's capacity crucial for improving the overall energy density of the battery cell.

[0005] Limited by the interlayer spacing, graphite-based materials are unsuitable as negative electrode materials for sodium-ion batteries. However, hard carbon materials exhibit a greater degree of disorder when treated at high temperatures. These materials offer advantages such as a rich sodium storage environment, high reversible capacity, minimal volume deformation during sodium insertion / extraction, and a low redox potential. These materials are expected to become the first commercially viable negative electrode materials for sodium-ion batteries. However, hard carbon materials suffer from a low compaction density. Therefore, increasing the compaction density of hard carbon materials while maintaining a high sodium storage capacity is an urgent challenge in this field. Summary of the Invention

[0006] The embodiments of the present application provide a negative electrode material and a preparation method, a negative electrode plate, a sodium ion battery and an electronic device. Due to its unique composite structure, the negative electrode material can improve the compaction density while ensuring a high sodium storage capacity.

[0007] In order to achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0008] In the first aspect, an embodiment of the present application provides a negative electrode material, which includes carbonaceous particles, and the carbonaceous particles include first amorphous carbon particles and second amorphous carbon particles. The first amorphous carbon particles are blocky structures, and the second amorphous carbon particles are spherical hard carbon structures. The Dv50 particle size of the second amorphous carbon particles is smaller than the Dv50 particle size of the first amorphous carbon particles, and the sphericity of the second amorphous carbon particles B is 0.7-1.0.

[0009] Since the carbonaceous particles include first amorphous carbon particles and second amorphous carbon particles, the structure of the second amorphous carbon particles is spherical, and the Dv50 particle size of the second amorphous carbon particles is smaller than the Dv50 particle size of the first amorphous carbon particles, the second amorphous carbon particles can fill the gaps between multiple first amorphous carbon particles, thereby increasing the compaction density. Moreover, since amorphous carbon particles are used, the present application can achieve an increase in the compaction density while ensuring a high sodium storage capacity.

[0010] In one possible design, the Dv50 particle size ratio of the first amorphous carbon particles to the second amorphous carbon particles is 1:(0.1-0.6).

[0011] In a possible design, the mass mixing ratio of the first amorphous carbon particles to the second amorphous carbon particles is 10:(0.5-7).

[0012] In one possible design, the Dv50 of the first amorphous carbon particles is 4.0 μm to 10.0 μm, the particle size distribution value S1 of the first amorphous carbon particles is 1.0 to 1.8, and the particle size distribution value S1 = (Dv90 - Dv10) / Dv50.

[0013] In one possible design, the Dv50 of the second amorphous carbon particles is 1.0 μm to 4.0 μm, the particle size distribution value S2 of the second amorphous carbon particles is 0.5 to 1.6, and the particle size distribution value S2 = (Dv90 - Dv10) / Dv50.

[0014] In one possible design, the particle size distribution (PSD) test result of the negative electrode material has a bimodal characteristic.

[0015] In a second aspect, an embodiment of the present application provides a method for preparing a negative electrode material, the preparation method mainly comprising:

[0016] The hard carbon precursor is subjected to pretreatment, precarbonization, crushing, first high-temperature carbonization, screening and demagnetization to obtain first amorphous carbon particles with a block structure;

[0017] A spherical amorphous carbon precursor is prepared by a polysaccharide hydrothermal method and polymer resin native polymerization, and the spherical amorphous carbon precursor is subjected to a second high-temperature carbonization, crushing, screening and demagnetization to obtain a second amorphous carbon particle with a spherical hard carbon structure;

[0018] The first amorphous carbon particles and the second amorphous carbon particles are mixed to obtain a negative electrode material.

[0019] In one possible design, mixing the first amorphous carbon particles with the second amorphous carbon particles to obtain the negative electrode material includes: mixing the first amorphous carbon particles with the second amorphous carbon particles in a mass ratio of 10:(0.5-7) to obtain the negative electrode material.

[0020] In one possible design, the Dv50 particle size of the second amorphous carbon particles is smaller than the Dv50 particle size of the first amorphous carbon particles.

[0021] In one possible design, the Dv50 particle size ratio of the first amorphous carbon particles to the second amorphous carbon particles is 1:(0.1-0.6).

[0022] In one possible design, the sphericity of the second amorphous carbon particles is 0.7-1.0.

[0023] In a possible design, the pre-carbonization temperature is set to 300°C-600°C, and the first high-temperature carbonization temperature is set to 1200°C-1500°C.

[0024] In a possible design, the temperature of the second high-temperature carbonization is set to 1200°C - 1500°C.

[0025] The negative electrode material obtained by the above preparation method can improve the compaction density while ensuring high sodium storage capacity.

[0026] In a third aspect, an embodiment of the present application provides a negative electrode plate, which includes a negative electrode collector and a negative electrode material layer arranged on at least one side of the negative electrode collector, and the negative electrode material layer includes the negative electrode material mentioned in the first aspect or the negative electrode material prepared by the preparation method of the second aspect.

[0027] 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, wherein the electrolyte is filled between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet includes the negative electrode material mentioned in the first aspect or the negative electrode material prepared by the preparation method mentioned in the second aspect.

[0028] In a fifth aspect, an embodiment of the present application further provides an electronic device, which includes a housing, and electronic components and a battery housed in the housing, wherein the battery supplies power to the electronic components, and the battery includes the sodium ion battery mentioned in the fourth aspect.

[0029] These and other aspects of the present application will be more clearly understood in the description of the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more clearly illustrate the embodiments of this application or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or descriptions of the prior art. Obviously, the drawings below only reflect some of the embodiments of this application. For those of ordinary skill in the art, other implementation methods of this application can be obtained based on these drawings without inventive work. All of these embodiments or implementation methods are within the scope of protection of this application.

[0031] FIG1 is a schematic structural diagram of a sodium ion battery provided in an embodiment of the present application;

[0032] FIG2 is a schematic structural diagram of a negative electrode material provided in an embodiment of the present application;

[0033] FIG3 is a flow chart for preparing a high-pressure sodium amorphous carbon negative electrode material provided in an embodiment of the present application;

[0034] FIG4 is a microstructure diagram of a high-pressure sodium amorphous carbon negative electrode material provided in an embodiment of the present application;

[0035] FIG5 is a microstructure slice diagram of the high-pressure sodium amorphous carbon negative electrode material provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] The solutions described in the embodiments of this application are intended to more clearly illustrate the technical solutions of this application and do not constitute a limitation on the technical solutions of this application. Ordinary technicians in this field can know that the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0038] Those skilled in the art will understand that words such as "first", "second", "S01", "S02", etc. do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit them to be 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 described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0039] For ease of understanding, some examples of concepts related to the embodiments of this application are provided for reference as follows:

[0040] Cathode: In a primary cell, the electrode from which current flows has a higher potential and is the positive electrode, gaining electrons to perform a reduction process. In an electrolytic cell, the positive electrode is the electrode connected to the positive terminal of the power supply and loses electrons to perform an oxidation process.

[0041] Anode: In a primary cell, the electrode into which current flows has a lower potential and is the negative electrode, losing electrons and causing oxidation. In an electrolytic cell, the anode is the electrode connected to the negative terminal of the power supply and receives electrons and causes reduction.

[0042] Electrolyte: A medium that provides ion exchange between the positive and negative electrodes of a battery.

[0043] Separator: The primary function of a separator is to separate the positive and negative electrodes of a battery, preventing contact and short circuits. It also allows electrolyte ions to pass through. Energy density: A measure of the amount of energy stored per unit volume or mass of a substance. A battery's energy density is the average amount of electrical energy released per unit volume or mass. Battery energy density is generally categorized into two dimensions: gravimetric energy density and volumetric energy density. The higher the battery's energy density, the more energy it can store per unit volume or weight.

[0044] Compacted density refers to the density of the electrode after the material is made into an electrode. Generally speaking, within the material's allowable compaction range, the higher the electrode's compacted density, the higher the battery's capacity. Therefore, compacted density is also considered a reference indicator of a material's energy density.

[0045] Tap density is the density of a material after vibration. Specifically, tap density is a key indicator of powder quality. Tap density measurement involves placing a certain amount of powder into a container and regularly vibrating it under certain conditions to minimize the gaps between particles until they can no longer be reduced. When the volume of the powder in the container stops decreasing, the volume of the powder is measured. The tap density of the powder is then calculated by dividing the weight of the powder by the volume.

[0046] Specific capacity: This mainly includes mass specific capacity and volume specific capacity. Mass specific capacity is the ratio of capacity to mass, and is used to indicate the amount of electricity that can be discharged per unit mass of a battery or active material. Volumetric specific capacity is the ratio of capacity to volume, and is used to indicate the amount of electricity that can be discharged per unit volume of a battery or active material.

[0047] La value: the average size of graphite crystals along the a-axis;

[0048] Lc value: It is the thickness of the ink sheet stacked along the c-axis direction perpendicular to it. It varies with the type of carbon and can be as small as 1 nanometer or as large as 10 microns or larger. It is generally determined by X-ray diffraction.

[0049] D002 interlayer spacing: refers to the distance between the layered structures in the material.

[0050] Coulombic efficiency, also known as discharge efficiency, Faraday efficiency, or current efficiency, refers to the ratio of a battery's discharge capacity to its charge capacity during the same cycle, or the percentage of discharge capacity to charge capacity. Initial coulombic efficiency (ICE) is a performance metric used to quantify the performance of a battery's negative electrode material. It is the ratio of the battery's discharge capacity to its charge capacity during its first charge-discharge cycle. As battery capacity decreases over the course of the charge-discharge cycle, the initial coulombic efficiency represents the peak of a battery's lifespan.

[0051] Sphericity: A parameter used to characterize particle morphology. The closer a particle's morphology is to a sphere, the closer its sphericity is to 1. Its specific value refers to the ratio of the surface area of ​​a sphere of the same volume to the surface area of ​​the object.

[0052] Sheet resistor: A resistor used in batteries and other electronic devices. Its resistance is determined by factors such as the diaphragm material, thickness, area, temperature, and humidity. In batteries, the sheet resistor primarily regulates current and protects the battery.

[0053] Dv50: Used to indicate the particle size corresponding to when the cumulative particle size distribution percentage of the sample reaches 50%.

[0054] Dv10: Used to indicate the particle size corresponding to when the cumulative particle size distribution percentage of the sample reaches 10%.

[0055] Dv90: Used to indicate the particle size corresponding to when the cumulative particle size distribution percentage of the sample reaches 90%.

[0056] Amorphous carbon: also known as transition carbon, refers to carbon materials with very low degrees of graphitization and crystallization, which are close to amorphous forms (or have no fixed shape and periodic structural regularity). Amorphous carbon has the characteristics of large interlayer spacing and disordered microcrystalline structure. It is widely used in activated carbon, fuel, metallurgy, sodium ion batteries and other fields. According to the degree of graphitization difficulty, amorphous carbon can be divided into two categories: soft carbon and hard carbon. Soft carbon, also known as easily graphitized carbon, refers to carbon that can be graphitized after high-temperature treatment. Hard carbon, also known as non-graphitized carbon, refers to carbon that cannot be graphitized after high-temperature treatment above 2800 degrees Celsius. The internal crystal arrangement of hard carbon is disordered and there are more pores. Due to its structural characteristics, hard carbon has a better sodium storage capacity than soft carbon, making it an ideal negative electrode material for sodium ion batteries.

[0057] The present invention provides a sodium-ion battery. FIG1 is a schematic diagram of the structure of the sodium-ion battery provided in the present invention. As shown in FIG1 , the sodium-ion battery includes a positive electrode sheet 10, a negative electrode sheet 20, a separator 30, and an electrolyte 40. 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 infiltrates 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 in the negative electrode material 202 of the negative electrode sheet 20. During discharge, 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. The positive electrode material 102 and the negative electrode material 202 are the main components of the sodium-ion battery that perform the energy storage function. The negative electrode material 202 is also the most direct embodiment of the energy density, cycle performance, and safety performance of the battery cell.

[0058] Continuing with Figure 1 , in the sodium-ion battery provided in the embodiments of the present application, the separator 30 blocks the passage of electrons while allowing the passage of ions. 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. In a sodium-ion battery, the electrolyte 40 serves as the transmission medium for sodium ions between the positive electrode 10 and the negative electrode 20.

[0059] As shown in FIG1 , 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 . The positive electrode material layer may include not only the positive electrode material 102 but also a certain amount of binder, conductive agent and other components.

[0060] The positive electrode current collector 101 can be a metal foil, such as aluminum foil, gold foil, or platinum foil. The positive electrode material 102 can reversibly intercalate and deintercalate sodium ions. The positive electrode material 102 includes, but is not limited to, at least one of a layered sodium transition metal oxide, a Prussian white compound, a Prussian blue compound, and a sodium polyanionic compound.

[0061] Sodium transition metal oxides such as sodium nickel iron manganese (NaNi1 / 3Fe1 / 3Mn1 / 3O2, NFM111), Prussian white compounds such as (Na2Mn[Fe(CN)6], PBA), Prussian blue compounds such as (NaMn[Fe(CN)6], PBA), sodium polyanionic compounds such as sodium iron phosphate (NaFePO4, NFP), sodium iron sulfate (Na2Fe2(SO4)3, NFS). The binder can be, for example, polyvinylidene fluoride (poly 1,1 difluoroethylene, PVDF), and the conductive agent can be, for example, conductive carbon black (super P), graphite, amorphous carbon, carbon nanotubes, carbon fiber, graphene, etc. The above-mentioned positive electrode current collector 101, positive electrode material 102, binder and conductive agent for preparing the positive electrode plate 10 are only exemplary, and the embodiments of the present application are not limited thereto. Taking the positive electrode material 102 as an example, in theory, it can be a compound that can reversibly embed / de-embed sodium ions.

[0062] Continuing to refer to FIG1 , in the sodium ion battery provided in the embodiment of the present application, the negative electrode plate 20 includes a negative electrode current collector 201 and a negative electrode material layer coated on the surface of the negative electrode 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 electrode 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 electrode current collector 201, binder and conductive agent used to prepare the negative electrode plate 20 are only exemplary descriptions and are not limited in this embodiment of the present application.

[0063] In one embodiment of the present application, referring to FIG2 , the negative electrode material 202 may include carbonaceous particles, which may include a first amorphous carbon and a second amorphous carbon, wherein the first amorphous carbon is a block structure, the second amorphous carbon is a spherical hard carbon structure, the Dv50 particle size of the second amorphous carbon is smaller than the Dv50 particle size of the first amorphous carbon, and the sphericity of the second amorphous carbon B is 0.7-1.0.

[0064] It should be noted that the bulk structure of the first amorphous carbon refers to a non-spherical hard carbon structure, and may be a regular or irregular bulk structure such as a rod-like, plate-like, or angular-like structure.

[0065] Since the carbonaceous particles include first amorphous carbon particles and second amorphous carbon particles, the structure of the second amorphous carbon particles is spherical, and the Dv50 particle size of the second amorphous carbon particles is smaller than the Dv50 particle size of the first amorphous carbon particles, the second amorphous carbon particles can fill the gaps between multiple first amorphous carbon particles, thereby increasing the compaction density. Moreover, since amorphous carbon particles are used, the present application can achieve an increase in the compaction density while ensuring a high sodium storage capacity.

[0066] In one embodiment, a Dv50 particle size ratio of the first amorphous carbon particles to the second amorphous carbon particles is 1:(0.1-0.6).

[0067] In one embodiment, the mass mixing ratio of the first amorphous carbon particles to the second amorphous carbon particles is 10:(0.5-7).

[0068] In one embodiment, Dv50 of the first amorphous carbon particles is 4.0 μm to 10.0 μm, and the particle size distribution value S1 of the first amorphous carbon particles is 1.0 to 1.8, and the particle size distribution value S1 = (Dv90 - Dv10) / Dv50.

[0069] In one embodiment, the Dv50 of the second amorphous carbon particles is 1.0 μm to 4.0 μm, the particle size distribution value S2 of the second amorphous carbon particles is 0.5 to 1.6, and the particle size distribution value S2 = (Dv90 - Dv10) / Dv50.

[0070] In one embodiment, a particle size distribution (PSD) test result of the negative electrode material has a bimodal characteristic.

[0071] The present application also provides a method for preparing a negative electrode material. FIG3 is a flow chart of the preparation of the negative electrode material provided in the present application, which mainly includes three steps: S01, S02, and S03:

[0072] S01: Material preparation of the first amorphous carbon particles

[0073] The hard carbon precursor is subjected to raw material pretreatment, pre-carbonization, crushing, first high-temperature carbonization, and first screening and demagnetization to obtain first amorphous carbon particles.

[0074] In one embodiment, the temperature of the pre-carbonization is 300°C-600°C, and the temperature of the first high-temperature carbonization is 1200°C-1500°C.

[0075] S02: Material preparation of second amorphous carbon particles

[0076] A spherical amorphous carbon precursor is first prepared by hydrothermal polymerization of a polysaccharide and in-situ polymerization of a polymer resin, followed by a second high-temperature carbonization, pulverization, and a second screening and demagnetization step to obtain a second amorphous carbon particle. It should be noted that other preparation methods that can produce spherical carbon materials with the same powder parameters can also be used in this application.

[0077] In one embodiment, the temperature of the second high-temperature carbonization is 1200°C-1500°C.

[0078] S03: Mixing the first amorphous carbon particles and the second amorphous carbon particles

[0079] The first amorphous carbon particles and the second amorphous carbon particles are mixed in a certain ratio to obtain the high-density composite amorphous carbon negative electrode material provided in the embodiments of the present application. The mixing method can be mechanical mixing or direct mixing during the electrode plate homogenization process. The embodiments of the present application do not limit the mixing method.

[0080] It should be understood that the order of S01 and S02 is not fixed. In one embodiment, the first amorphous carbon particles can be prepared first, followed by the second amorphous carbon particles, and finally the first amorphous carbon particles and the second amorphous carbon particles are mixed in a certain ratio. In another embodiment, the second amorphous carbon particles can be prepared first, followed by the first amorphous carbon particles, and finally the first amorphous carbon particles and the second amorphous carbon particles are mixed in a certain ratio.

[0081] The first amorphous carbon particles are an amorphous carbon material component, and the second amorphous carbon particles are an amorphous carbon material component. More specifically, the first amorphous carbon particles are irregular block materials obtained by pre-treating a hard carbon precursor, carbonizing it at high temperature, and then crushing it. The second amorphous carbon particles are spherical hard carbon materials prepared by hydrothermal polymerization of polysaccharides and in-situ polymerization of polymer resins.

[0082] Optionally, the hard carbon precursor may be a biomass precursor (such as straw, rice husk), a synthetic resin precursor (such as phenolic resin), or an asphalt precursor and a sugar precursor, which is not limited in the embodiments of the present application.

[0083] The high-density hard carbon negative electrode material with composite components obtained by the above preparation method can significantly improve the compaction density and tap density, thereby effectively improving the processing performance of the material, and can also improve the volumetric capacity while ensuring the mass capacity.

[0084] Furthermore, the negative electrode sheet made of the negative electrode material has excellent performance, the peeling force will be effectively improved, and the film resistance will also be effectively reduced.

[0085] The negative electrode material and preparation method provided in this application will be described in detail below through specific examples.

[0086] Example 1

[0087] S01: Material preparation of the first amorphous carbon particles

[0088] The coconut shells are subjected to raw material pretreatment, pre-carbonization, pulverization, high-temperature carbonization, and screening for demagnetization to obtain first amorphous carbon particles. The first amorphous carbon particles have a block structure and specifically meet the following requirements: Dv50 is 5.0 microns and a particle size distribution value S1 ((Dv90-Dv10) / Dv50) = 1.35.

[0089] S02: Material preparation of second amorphous carbon particles

[0090] A spherical amorphous carbon precursor is prepared by in situ polymerization of phenol and formaldehyde, and then the second amorphous carbon particles are obtained through high-temperature carbonization, crushing, screening and demagnetization. The obtained spherical structured carbon second amorphous carbon particles have a spherical hard carbon structure, which specifically meets the following requirements: Dv50 is 2.0 microns, the particle size distribution value S ((Dv90-Dv10) / Dv50) = 1.55, and the sphericity is 0.98.

[0091] S03: Mixing the first amorphous carbon particles and the second amorphous carbon particles in a certain proportion

[0092] The first amorphous carbon particles and the second amorphous carbon particles are mixed in a mass ratio of 10:2 to obtain a high-pressure sodium amorphous carbon negative electrode material with a composite component.

[0093] Example 2

[0094] The mass mixing ratio of the first amorphous carbon particles and the second amorphous carbon particles was adjusted. That is, the first amorphous carbon particles and the second amorphous carbon particles were mixed at a mass ratio of 10:3 to obtain a high-density composite amorphous carbon negative electrode material. The other parameters were the same as those in Example 1.

[0095] Example 3

[0096] The mass mixing ratio of the first amorphous carbon particles and the second amorphous carbon particles was adjusted. That is, the first amorphous carbon particles and the second amorphous carbon particles were mixed at a mass ratio of 10:5 to obtain a high-density composite amorphous carbon negative electrode material. The other parameters were the same as those in Example 1.

[0097] Example 4

[0098] The Dv50 value of the first amorphous carbon particles was changed to 8.0 μm, and the remaining parameters were the same as those in Example 1.

[0099] Example 5

[0100] The Dv50 value of the second amorphous carbon particles was changed to 4.0 μm, and the remaining parameters were the same as those in Example 1.

[0101] Example 6

[0102] The Dv50 value of the first amorphous carbon particles and the second amorphous carbon particles are adjusted, as well as the mass mixing ratio of the first amorphous carbon particles and the second amorphous carbon particles, to obtain composite amorphous carbon negative electrode materials with different performances. The specific preparation process and requirements are as follows:

[0103] S01: Material preparation of the first amorphous carbon particles

[0104] The thermosetting resin is subjected to raw material pretreatment, precarbonization, pulverization, high-temperature carbonization, and screening and demagnetization to obtain first amorphous carbon particles. The obtained first amorphous carbon particles satisfy: Dv50 of 6.0 microns and a particle size distribution value S1 ((Dv90-Dv10) / Dv50) = 1.28.

[0105] S02: Material preparation of second amorphous carbon particles

[0106] A spherical amorphous carbon precursor was prepared using a glucose hydrothermal method, and then a second amorphous carbon particle was obtained through high-temperature carbonization, crushing, screening and demagnetization. The obtained spherical structured carbon second amorphous carbon particles met the following requirements: Dv50 was 2.5 microns, the particle size distribution value S((Dv90-Dv10) / Dv50)=1.49, and the sphericity was 0.85.

[0107] S03: Proportional mixing of the first amorphous carbon particles and the second amorphous carbon particles

[0108] The first amorphous carbon particles and the second amorphous carbon particles are mixed at a mass ratio of 10:4 to obtain a high-density composite amorphous carbon negative electrode material.

[0109] In order to more intuitively illustrate the influence of various specific parameters on the overall powder structure performance of the negative electrode material, the present application will also exemplarily give four comparative examples.

[0110] Comparative Example 1

[0111] The sample provided in this comparative example is a single first amorphous carbon particle, and the parameters of the first amorphous carbon particle are the same as those of the first amorphous carbon particle in Example 1.

[0112] Comparative Example 2

[0113] The sample provided in this comparative example is a single second amorphous carbon particle, and the parameters of the second amorphous carbon particle are the same as those of the second amorphous carbon particle in Example 1.

[0114] Comparative Example 3

[0115] In the sample provided in this comparative example, the particle size Dv50 of the second amorphous carbon particles was adjusted to 5.0 μm, and other parameters of the second amorphous carbon particles remained unchanged. The parameters of the first amorphous carbon particles were the same as those in Example 1.

[0116] Comparative Example 4

[0117] In the sample provided in this comparative example, the sphericity of the second amorphous carbon particles was adjusted to 0.2, that is, the morphology of the second amorphous carbon particles was adjusted, and other parameters remained unchanged. The parameters of the first amorphous carbon particles were the same as those in Example 1.

[0118] The negative electrode materials prepared in Examples 1-6 and Comparative Examples 1-4, as well as the corresponding sodium ion batteries, were subjected to performance tests. The test results are shown below:

[0119] In some embodiments of the present application, the morphology and structure of the negative electrode material provided in the embodiments of the present application are scanned by electron microscope as a basis for further analysis, see Figures 4 and 5. Among them, Figure 4 is a microscopic structure diagram of the high-pressure sodium-electric amorphous carbon negative electrode material provided in the embodiments of the present application, and Figure 5 is a microscopic slice diagram of the high-pressure sodium-electric amorphous carbon negative electrode material provided in the embodiments of the present application. As shown in Figures 4 and 5, the first amorphous carbon particles are block structures, and the second amorphous carbon particles are spherical hard carbon structures. The uniform mixing and distribution of the first amorphous carbon particles and the second amorphous carbon particles effectively ensures effective electrical contact between the particles. At the same time, it also ensures the effective and rapid transmission of electrons and ions during the charging and discharging process of the battery.

[0120] In other embodiments of the present application, other microscopic techniques may also be used to characterize materials, such as optical microscopy, atomic force microscopy, etc., and the embodiments of the present application are not limited to this.

[0121] In some embodiments of the present application, in order to systematically characterize the effects of various parameters on the overall powder structure performance of the negative electrode material, the above samples (including embodiments and comparative examples) were technically characterized by tap density and compaction density, as shown in Table 1 below.

[0122] Table 1.

[0123] As described above, Comparative Example 1 is a single first amorphous carbon particle, Comparative Example 2 is a single second amorphous carbon particle, and Examples 1 to 6 are all composite components, i.e., a mixture of first amorphous carbon particles and second amorphous carbon particles. As shown in Table 1, compared to Comparative Examples 1 and 2, the tap density and compaction density of Examples 1 to 6 are significantly improved, which shows that the composite strategy of the first amorphous carbon particles and the second amorphous carbon particles can improve the performance of the corresponding samples. Compared with Example 1, Comparative Example 3 increases the particle size of the second amorphous carbon particles. As shown in Table 1, compared with Example 1, when the particle size of the second amorphous carbon particles becomes larger, the compaction density of the sample will become lower accordingly. Compared with Example 1, Comparative Example 4 reduces the sphericity of the second amorphous carbon particles and adjusts the morphology of the second amorphous carbon particles. As shown in Table 1, compared with Example 1, a smaller sphericity will correspondingly reduce the tap density and compaction density of the sample.

[0124] Furthermore, in order to characterize the role of the material in improving the electrochemical performance of sodium electrolytes, we characterized the material's charge-discharge test capacity, coulombic efficiency, electrode compaction, and diaphragm resistance.

[0125] As shown in Table 2, compared with Comparative Examples 1 and 2, the compaction density of the sample materials provided by Examples 1 to 6 using composite components has been greatly improved, and accordingly, the energy density of the battery can be improved synchronously. Compared with Comparative Examples 1 and 2, the membrane resistance of the sample materials provided by Examples 1 to 6 using composite components has been greatly reduced, thereby effectively improving the battery polarization and further improving the electrochemical performance of the battery. Compared with Comparative Examples 1 and 2, the volumetric capacity of the sample materials provided by Examples 1 to 6 using composite components has been effectively improved. Wherein, volumetric capacity = mass capacity * compaction density.

[0126] Furthermore, a comparison of the performance characteristics of Example 1 and Comparative Example 3 shows that the particle size of the second amorphous carbon particles significantly affects the electrochemical performance of the composite negative electrode material. Specifically, a larger particle size of the second amorphous carbon particles increases the sheet resistance of the composite negative electrode material, decreases the volumetric capacity, and decreases the mass capacity.

[0127] A comparison of the performance characteristics of Example 1 and Comparative Example 4 shows that the morphology of the second amorphous carbon particles significantly influences the electrochemical performance of the composite negative electrode material. Specifically, the less spherical the second amorphous carbon particles are, the greater the sheet resistance of the composite negative electrode material, the lower the volumetric capacity, the lower the mass capacity, and the lower the compaction density.

[0128] Table 2.

[0129] To sum up, on the one hand, the technical characterization of the negative electrode material with composite components is significantly better than that of the negative electrode material with single component; on the other hand, the Dv50 value of the second amorphous carbon particles needs to be smaller than the Dv50 value of the first amorphous carbon particles, and the sphericity of the second amorphous carbon particles also needs to be controlled at a certain value.

[0130] An embodiment of the present application also provides a negative electrode plate, which includes a negative electrode current collector and a negative electrode material layer arranged on at least one side of the negative electrode current collector, and the negative electrode material layer includes the above-mentioned negative electrode material or the negative electrode material prepared by the above-mentioned preparation method.

[0131] An embodiment of the present application also provides a sodium ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator located between the positive electrode sheet and the negative electrode sheet, and an electrolyte, wherein the electrolyte is filled between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet comprises a negative electrode material or a negative electrode material prepared by a related preparation method.

[0132] An embodiment of the present application further provides an electronic device, which includes a housing, and electronic components and a battery housed in the housing. The battery supplies power to the electronic components, and the battery includes the sodium ion battery described above.

[0133] Electronic devices may include, for example, mobile phones, smart screens, tablet computers, personal computers (PCs), personal digital assistants (PDAs), smart watches, power banks, netbooks, wearable devices, augmented reality (AR) devices, virtual reality (VR) devices, vehicle-mounted devices, energy storage devices, base stations, and automobiles. The embodiments of the present application do not impose any special restrictions on the specific form of the electronic device.

[0134] In some embodiments, multiple embodiments of the present application may be combined and the combined embodiments may be implemented. Optionally, some operations in the processes of the various method embodiments may be optionally combined, and / or the order of some operations may be optionally changed. Furthermore, the execution order between the steps of each process is merely exemplary and does not constitute a limitation on the execution order between the steps. Other execution orders may also be used between the steps. This is not intended to indicate that the execution order is the only order in which these operations may be performed.

[0135] Those skilled in the art will appreciate 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 also applicable to other embodiments in a similar manner, or different embodiments can be used in combination.

[0136] In addition, some steps in the method embodiment may be equivalently replaced with other possible steps. Alternatively, some steps in the method embodiment may be optional and may be deleted in certain usage scenarios. Alternatively, other possible steps may be added to the method embodiment. Moreover, each method embodiment may be implemented separately or in combination. The above content is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed in the present application shall be covered within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be based on the scope of protection of the claims.

[0137] In addition, this application mainly provides a detailed description of sodium battery negative electrode materials. It should be emphasized that the design concept of this composite material also has the same guiding significance for material design in other fields. Therefore, patents based on similar ideas in other fields are also within the scope of protection of this application.

Claims

1. A negative electrode material, characterized in that, The negative electrode material includes carbonaceous particles, which include first amorphous carbon particles and second amorphous carbon particles. The first amorphous carbon particles have a block structure, and the second amorphous carbon particles have a spherical hard carbon structure. The Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles, and the sphericity of the second amorphous carbon particles B is 0.7 - 1.

0.

2. The negative electrode material according to claim 1, characterized in that, The ratio of the Dv50 particle size of the first amorphous carbon particles to that of the second amorphous carbon particles is 1:(0.1 - 0.6).

3. The negative electrode material according to claim 1 or 2, characterized in that, The mass ratio of the first amorphous carbon particles to the second amorphous carbon particles is 10:(0.5 - 7).

4. The negative electrode material according to any one of claims 1 to 3, characterized in that, The Dv50 of the first amorphous carbon particles is 4.0 - 10.0 microns, and the particle size distribution value S1 of the first amorphous carbon particles is 1.0 - 1.

8. The particle size distribution value S1 = (Dv90 - Dv10) / Dv50.

5. The negative electrode material according to any one of claims 1-4, characterized in that, The Dv50 of the second amorphous carbon particles is 1.0 - 4.0 microns, and the particle size distribution value S2 of the second amorphous carbon particles is 0.5 - 1.

6. The particle size distribution value S2 = (Dv90 - Dv10) / Dv50.

6. The negative electrode material according to any one of claims 1-5, characterized in that, The PSD test result of the particle size distribution of the negative electrode material has a bimodal characteristic.

7. A method for preparing a negative electrode material, characterized in that, The method includes: Subjecting the hard carbon precursor to pretreatment, pre-carbonization, pulverization, first high-temperature carbonization, and first screening and demagnetization to obtain first amorphous carbon particles with a block structure; Using the polysaccharide hydrothermal method and in-situ polymerization of polymer resin to prepare a spherical amorphous carbon precursor, and subjecting the spherical amorphous carbon precursor to second high-temperature carbonization, pulverization, and second screening and demagnetization to obtain second amorphous carbon particles with a spherical hard carbon structure; Mixing the first amorphous carbon particles and the second amorphous carbon particles to obtain a negative electrode material.

8. The preparation method according to claim 7, characterized in that, Mixing the first amorphous carbon particles and the second amorphous carbon particles to obtain a negative electrode material includes: Mixing the first amorphous carbon particles and the second amorphous carbon particles according to a mass ratio of 10:(0.5 - 7) to obtain the negative electrode material.

9. The preparation method according to claim 7 or 8, characterized in that, The Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles.

10. The preparation method according to any one of claims 7-9, characterized in that, The sphericity of the second amorphous carbon particles is 0.7 - 1.

0.

11. A negative electrode plate, characterized in that, The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer provided on at least one side of the negative electrode current collector. The negative electrode material layer includes the negative electrode material according to any one of claims 1 - 6 or the negative electrode material prepared by the preparation method according to any one of claims 7 - 10.

12. A sodium-ion battery, characterized in that, The sodium ion battery 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 according to any one of claims 1 - 6 or the negative electrode material prepared by the preparation method according to any one of claims 7 - 10.

13. An electronic device, characterized in that, The electronic device includes a housing, and electronic components and a battery accommodated in the housing. The battery powers the electronic components, and the battery includes the sodium-ion battery described in claim 12.

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