Negative electrode material, secondary battery, and electric device

Abstract

Provided are a negative electrode material, a secondary battery, and an electric device. The negative electrode material comprises a carbonaceous material, and satisfies the following relational expression: 0.4≤DV50×S / [|P-OI / 4.8|×210]≤1.1, wherein DV50 μm represents the corresponding particle size when the cumulative volume percentage of the negative electrode material reaches 50%; S m2 / g represents the specific surface area of the negative electrode material; P g / cm3 represents the powder compaction density of the negative electrode material under a load of 5 T; and OI represents the degree of graphite orientation of the negative electrode material, and is a peak intensity ratio of a diffraction peak (004) to a diffraction peak (110) in an XRD pattern.

Description

A negative electrode material, a secondary battery, and an electrical device.

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese invention patent application CN202510473930.7, filed on April 14, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and in particular to a negative electrode material, a secondary battery, and an electrical device. Background Technology

[0004] Secondary batteries, especially lithium-ion batteries, are widely used in many industries due to their advantages such as high energy / power density, long cycle life, and zero pollution. As the demand for cost reduction in power batteries becomes increasingly prominent, lower-cost natural graphite anode materials are being used in power batteries. However, compared with artificial graphite, natural graphite has poor fast charging and high-temperature performance, making it difficult to meet the market's growing demand for fast charging performance in power batteries. Summary of the Invention

[0005] This application provides a negative electrode material, a secondary battery, and an electrical device.

[0006] A first aspect of this application provides a negative electrode material, said negative electrode material comprising a carbonaceous material, said negative electrode material satisfying the following relationship: 0.4≤D V 50×S / [∣P-OI / 4.8∣×210]≤1.1;

[0007] In the formula, D V 50 μm represents the particle size corresponding to a cumulative volume percentage of 50% for the negative electrode material;

[0008] S m 2 / g represents the specific surface area of ​​the negative electrode material;

[0009] P g / cm 3 This indicates the compaction density of the negative electrode material under 5T pressure;

[0010] OI represents the graphite orientation degree of the negative electrode material, which is the ratio of the peak intensity of the (004) diffraction peak to the (110) diffraction peak in the XRD pattern.

[0011] In some embodiments, the negative electrode material satisfies: 0.9 ≤ D V 50×S / [∣P-OI / 4.8∣×210]≤1.02.

[0012] In some embodiments, the powder compaction density P of the negative electrode material under a pressure of 5T is... 3 Satisfies: P < 1.7.

[0013] In some embodiments, the specific surface area S m of the negative electrode material 2 / g satisfies: 0.6≤S≤5.

[0014] In some embodiments, the particle size D of the negative electrode material V 50μm satisfies: 11≤D V 50≤20.

[0015] In some embodiments, the powder compaction density P of the negative electrode material under a pressure of 5T is... 3 It satisfies: 1.61≤P<1.70.

[0016] In some embodiments, the specific surface area S m of the negative electrode material 2 / g satisfies: 1.89≤S≤3.54.

[0017] In some embodiments, the particle size distribution of the negative electrode material satisfies: 1.0 ≤ (D V 90-D V 10) / D V 50≤2.1;D V 90 μm represents the particle size corresponding to a cumulative volume percentage of 90% for the negative electrode material; D V 10 μm represents the particle size corresponding to a cumulative volume percentage of 10% for the negative electrode material; D V 50 μm represents the particle size corresponding to a cumulative volume percentage of 50% for the negative electrode material.

[0018] In some implementations, 4μm≤D V 10μm≤15μm.

[0019] In some implementations, 20μm≤D V 90μm≤45μm.

[0020] The compacted density of the negative electrode material powder satisfies: P g / cm³ 3 -A g / cm 3 ≥0.2g / cm 3 P g / cm 3 This represents the compacted density of the negative electrode material under a pressure of 5T; Ag / cm³ 3 This indicates the compaction density of the negative electrode material under a pressure of 2T.

[0021] In some embodiments, the powder compaction density of the negative electrode material satisfies: 0.20 g / cm³. 3 ≤Pg / cm 3 -Ag / cm 3 ≤0.23g / cm 3 .

[0022] In some embodiments, the powder compaction density A of the negative electrode material under a pressure of 2T satisfies: 1.35 g / cm³. 3 ≤Ag / cm 3 ≤1.50g / cm 3 .

[0023] In some embodiments, the degree of graphitization of the negative electrode material is 92% to 96%.

[0024] In some embodiments, the powder OI value (graphite orientation degree) of the negative electrode material is 1 to 12.

[0025] In some embodiments, the specific capacity of the negative electrode material is 340 mAh / g to 360 mAh / g.

[0026] A second aspect of this application provides a secondary battery, the secondary battery comprising a positive electrode, an electrolyte, a separator, and a negative electrode, the negative electrode comprising a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, the negative electrode material layer comprising the negative electrode material described in the first aspect of this application.

[0027] A third aspect of this application also provides an electrical device, which includes the secondary battery described in the second aspect of this application.

[0028] Compared with the prior art, the beneficial effects of this application are:

[0029] This application achieves excellent fast-charging performance and cycle stability (especially high-rate cycle performance) by controlling the particle size, specific surface area, powder compaction density, and OI value of the carbon-based anode material to meet certain relationships, and also has the advantage of low cost. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0032] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0033] The term "carbon materials" (or "carbon-based materials") as used in this article refers to all anode materials that are primarily composed of carbon and can be used for lithium-ion insertion and extraction; non-limiting examples include graphite, soft carbon, hard carbon, etc.

[0034] Unless otherwise specified, all reagents or instruments used in this application are commercially available products.

[0035] A first aspect of this application provides a negative electrode material, said negative electrode material comprising a carbonaceous material, said negative electrode material satisfying the following relationship: 0.4≤D V 50×S / [∣P-OI / 4.8∣×210]≤1.1;

[0036] In the formula, D V 50 μm represents the particle size corresponding to a cumulative volume percentage of 50% for the negative electrode material;

[0037] S m 2 / g represents the specific surface area of ​​the negative electrode material;

[0038] P g / cm 3 This indicates the compaction density of the negative electrode material under 5T pressure;

[0039] OI represents the graphite orientation degree of the negative electrode material, which is the ratio of the peak intensity of the (004) diffraction peak to the (110) diffraction peak in the XRD pattern.

[0040] The inventors of this application have discovered that for secondary batteries using carbon materials as anode materials, by adjusting the particle size, specific surface area, powder compaction density, and OI value of the carbon anode material to meet reasonable ranges, the fast charging performance of the secondary battery, especially its cycle performance at high rates, can be effectively improved.

[0041] In this application, D V 50. D V10. D V The particle size was measured using a laser diffractometer, referring to Appendix A of GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries". Specific surface area was measured using GB / T19587-2017 "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method". Powder compaction density was measured using a powder compaction density meter under different pressures, referring to Appendix L of GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries". Graphite orientation (OI value) was measured using X-ray diffraction, referring to Appendix R of GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries".

[0042] In some embodiments of this application, D V The value of 50×S / [∣P-OI / 4.8∣×210] can be any one of the following values ​​or any interval formed by any two values: 0.430, 0.477, 0.540, 0.600, 0.690, 0.720, 0.810, 0.844, 0.893, 0.981, and 1.107.

[0043] In some embodiments of this application, the powder compaction density of the negative electrode material under 5T pressure is Pg / cm³. 3 Satisfying the condition: P < 1.7. A smaller powder compaction density of the negative electrode material increases the interparticle distance and the number of ion channels, which is beneficial for electrolyte wetting and, consequently, for rapid ion movement, giving the battery good fast-charging performance. However, excessive interparticle distance reduces the probability and area of ​​particle contact, hindering electronic conductivity, increasing discharge polarization, internal resistance, and reducing discharge capacity. It also makes the battery more susceptible to structural damage during charging and discharging, affecting cycle life. The inventors of this application have discovered that when the particle size, specific surface area, and powder compaction density of the carbon-based negative electrode material are controlled to satisfy the above relationship, it is possible to improve the battery's fast-charging performance while maintaining both high discharge capacity and low resistance at a lower powder compaction density, thus giving the battery good fast-charging and discharging performance. In some embodiments of this application, the powder compaction density P of the negative electrode material at 5T pressure is... 3 The condition 1.61 ≤ P ≤ 1.70 is satisfied. In this application, P g / cm³ 3 The value can be 1.61 g / cm³. 3 1.62g / cm 3 1.64 g / cm 3 1.66 g / cm 3 1.68g / cm 3 1.70g / cm 3 The range formed by any one or any two values ​​in the range.

[0044] In some embodiments of this application, the powder compaction density of the negative electrode material further satisfies: Pg / cm 3 -Ag / cm 3 ≥0.2g / cm 3 P g / cm 3 This represents the compacted density of the negative electrode material under a pressure of 5T; Ag / cm³ 3 This represents the powder compaction density of the negative electrode material under a pressure of 2T. Adjusting the powder compaction density of the negative electrode material to meet this condition can further improve the kinetic performance of the battery. In some embodiments of this application, the powder compaction density of the negative electrode material satisfies: 0.20 g / cm³. 3 ≤P g / cm 3 -A g / cm 3 ≤0.23g / cm 3 In this application, the powder compaction density P of the negative electrode material under a pressure of 5T is... 3 The powder compaction density (Ag / cm³) of the negative electrode material under 2T pressure. 3 The difference can specifically be 0.20 g / cm³. 3 0.21g / cm 3 0.23g / cm 3 The range formed by any one or any two values ​​in the range.

[0045] In some embodiments of this application, the powder compaction density of the negative electrode material under 2T pressure is Ag / cm³. 3 Satisfying: 1.35g / cm 3 ≤Ag / cm 3 ≤1.50g / cm 3 In some embodiments, 1.39 g / cm³ 3 ≤Ag / cm 3 ≤1.50g / cm 3 In this application, the Ag / cm 3 The value can be 1.399 g / cm³. 3 1.407 g / cm 3 1.424 g / cm 3 1.463 g / cm 3 The range formed by any one or any two values ​​in the range.

[0046] In some embodiments of this application, the specific surface area S m of the negative electrode material 2 / g satisfies: 0.6 ≤ S ≤ 5. The S m 2 The value of / g can be 0.60m 2 / g, 1.10m 2 / g, 1.89m 2 / g, 2.12m 2 / g, 3.09m 2 / g, 3.54m 2 / g, 4.23m 2 / g, 5.00m 2 The range formed by any one or any two values ​​in / g. In some embodiments of this application, the specific surface area S m of the negative electrode material. 2 / g satisfies: 1.89≤S≤3.54.

[0047] In some embodiments of this application, the particle size D of the negative electrode material V 50μm satisfies: 11≤D V 50≤20. The D V The value of 50 μm can be any one of 11.0 μm, 14.0 μm, 14.5 μm, 16.2 μm, 19.0 μm, or 20.0 μm, or any range formed by two such values. When the D of the negative electrode material... V A lower D50 value is more conducive to electrolyte wetting, resulting in faster lithium-ion conduction within the active material particles, better battery kinetics, and less polarization. This reduces lithium deposition on the material surface, thus lowering safety risks. However, an excessively low D50 value can lead to excessive side reactions and accelerate the loss of active lithium. V A higher 50 value is beneficial for increasing battery energy density, but it also increases the difficulty of electrolyte wetting, hinders lithium ion transport within the active material particles, deteriorates battery kinetics, increases polarization, leads to lithium deposition on the material surface, accelerates battery capacity decay, and worsens cycle performance. V Within the aforementioned suitable range, 50 can simultaneously impart excellent dynamic performance and fast charging performance to the battery.

[0048] In some embodiments of this application, the negative electrode material satisfies: 4μm≤D V 10μm≤15μm. The D V The value of 10μm can be any one of the following values: 4μm, 5.1μm, 7.6μm, 8.9μm, 11.2μm, 12.5μm, and 15μm, or any range formed by any two values.

[0049] In some embodiments of this application, the negative electrode material satisfies: 20μm≤D V 90μm≤45μm. The D VThe value of 90μm can be any one of the following values: 20.0μm, 23.2μm, 28.5μm, 34.2μm, 41.7μm, 45.0μm, or any range formed by any two values.

[0050] In some embodiments of this application, the particle size distribution of the negative electrode material satisfies: 1.0 ≤ (D V 90-D V 10) / D V 50≤2.1;D V 90 μm represents the particle size corresponding to a cumulative volume percentage of 90% for the negative electrode material; D V 10 μm represents the particle size corresponding to a cumulative volume percentage of 10% for the negative electrode material; D V 50 μm represents the particle size corresponding to a cumulative volume percentage of 50% for the negative electrode material. The (D) V 90-D V 10) / D V The value of 50 can be any one of 1.00, 1.37, 1.61, 1.76, 1.92, or 2.10, or a range formed by any two values. The smaller the particle size of the negative electrode material powder, the larger the corresponding specific surface area and the more active sites, which is beneficial for ion conduction. However, excessively small particle size can easily lead to agglomeration, resulting in uneven distribution of the negative electrode material powder on the surface of the negative electrode sheet, thus causing uneven surface structure and affecting the cycle life of the battery. Therefore, when the particle size, particle size distribution, and specific surface area of ​​the negative electrode material powder are within the above-mentioned suitable ranges, the battery can be endowed with good kinetic performance.

[0051] In some embodiments of this application, the graphitization degree of the negative electrode material is 92% to 96%, specifically any one of 92.0%, 93.1%, 94.2%, 95.5%, and 96.0%, or a range formed by any two values. Graphitization degree refers to the degree of perfection of graphite crystals in the material. A higher graphitization degree indicates a more perfect graphite crystal structure, fewer defects within the crystal, more active centers and fast lithium-ion transport channels, reduced polarization, and promoted lithium-ion diffusion, thereby improving the fast-charging performance of the battery. The graphitization degree mentioned in this application refers to the value obtained by testing and calculating using an X-ray diffractometer according to the method specified in Appendix E of GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries".

[0052] In some embodiments of this application, the OI value (graphite orientation index) of the negative electrode material powder is 1 to 12, specifically any one of 1.0, 3.5, 6.2, 6.4, 9.3, and 12.0, or any range formed by any two values. The OI value, or Orientation Index, is a parameter describing the degree of orderliness of graphite sheet arrangement in graphite materials. It is obtained through XRD diffraction pattern analysis, specifically calculated by the intensity ratio of the (004) diffraction peak to the (110) diffraction peak. A smaller OI value indicates a higher probability that the layered structure in the negative electrode material is perpendicular to the current collector surface, resulting in a faster lithium-ion insertion and extraction rate, which is beneficial for improving fast-charging performance. However, it is difficult to increase the compaction density of the electrode sheet after pressure application, thus limiting the increase in discharge capacity. Therefore, controlling the OI value of the negative electrode material powder within the aforementioned suitable range can endow the battery with good fast-charging performance and discharge capacity.

[0053] In some embodiments of this application, the specific capacity of the negative electrode material is 340 mAh / g to 360 mAh / g, specifically any one of 340.0 mAh / g, 350.4 mAh / g, and 360.0 mAh / g, or a range formed by any two of these values. The specific capacity described in this application is a value obtained by performing a discharge specific capacity test on the sample using a battery tester, referring to the method specified in Appendix G of GB / T 24533-2019 "Graphite-based Anode Materials for Lithium-ion Batteries".

[0054] A second aspect of this application provides a secondary battery, the secondary battery comprising a positive electrode, an electrolyte, a separator, and a negative electrode, the negative electrode comprising a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, the negative electrode material layer comprising the negative electrode material described in the first aspect of this application.

[0055] In some embodiments of this application, the positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector, the positive electrode material layer including a positive electrode material.

[0056] This application does not limit the type of cathode material; commonly used cathode materials in the art can all be used to prepare secondary batteries in this application. The cathode materials include, but are not limited to, lithium iron phosphate (LiFePO4), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMnO2), lithium nickel oxide (LiNiO2), and lithium nickel cobalt manganese oxide (Li...). a Ni x Co y Mn zO2, where x+y+z=1, and 0<x<1, 0<y<1, 0<z<1, 0.9≤a≤1.1) are at least one of these. The cathode material can also be doped with elements to improve the battery's capacity and energy density.

[0057] This application does not limit the types of positive electrode current collector, negative electrode current collector, separator, and electrolyte; they can be selected according to requirements. Common current collector materials, separators, and electrolytes in the art can all be used in this application.

[0058] In some embodiments, the negative current collector may preferably be copper foil or carbon-coated copper foil.

[0059] The positive electrode current collector can be made of metal materials such as aluminum, stainless steel, nickel plating, titanium, tantalum, etc.; carbon materials such as carbon cloth, carbon paper, etc.; or composite materials formed by polymer and metal layer. In some embodiments, aluminum foil is preferably used as the positive electrode current collector.

[0060] In some embodiments, there is no limitation on the type of solvent used to form the positive electrode slurry and / or negative electrode slurry, as long as it is a solvent capable of dissolving or dispersing the positive electrode material, negative electrode material, conductive agent, binder, or dispersant.

[0061] In the secondary battery described in this application, the type of separator is not particularly limited and can be selected according to actual needs. The separator can be a polypropylene membrane, a polyethylene membrane, a polyvinylidene fluoride membrane, a spandex membrane, an aramid membrane, or a multilayer composite membrane modified with a coating.

[0062] In the secondary battery described in this application, the type of electrolyte is not particularly limited and can be selected according to actual needs.

[0063] In some embodiments of this application, the preparation of a secondary battery includes: stacking a positive electrode, a separator, and a negative electrode in sequence, with the separator acting as a separator between the positive and negative electrodes; then winding them into a square bare cell; inserting the cell into a battery casing; baking the cell at 65°C to 95°C to remove water; injecting electrolyte; sealing the cell; and then performing processes such as standing, hot and cold pressing, formation, clamping, and capacity testing to obtain a secondary battery.

[0064] In some embodiments, the secondary battery may include an outer packaging, which may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging may also be a soft pack, such as a pouch, made of plastic, such as one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate. The shape of the secondary battery is not particularly limited; it may be cylindrical, square, or any other arbitrary shape.

[0065] It is understood that this application primarily improves battery performance by controlling specific parameters in the negative electrode material. Correspondingly, this application does not impose special restrictions on other features, which can be conventionally selected based on common technical knowledge in the field. Other features include, but are not limited to: the type of current collector for the positive / negative electrode, the type of positive electrode material, the type and amount of conductive agent / binder / other additives for the positive / negative electrode, the separator, the electrolyte / electrolyte (including but not limited to its form, the type and amount of solvent, the type and amount of lithium salt, and the type and amount of other additives), the shape and packaging of the secondary battery, and other components and processes (including but not limited to the casing, tabs, encapsulation process, electrolyte injection process, and formation process). Furthermore, this application does not impose special restrictions on the preparation methods of the negative electrode material and the secondary battery. Those skilled in the art, after understanding the characteristics of the negative electrode material described in this application, can use conventional preparation processes in the field and adjust process parameters to prepare products possessing the characteristics described in this application.

[0066] A third aspect of this application provides an electrical device comprising the secondary battery described in the second aspect of this application. The electrical device can be an application device such as a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool. Vehicles can be new energy vehicles, including pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles; spacecraft include airplanes, rockets, space shuttles, and spacecraft; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. This application does not impose special limitations on the above-described device.

[0067] The following are specific embodiments of this application, and the technical solutions of this application are further described in conjunction with the embodiments. However, this application is not limited to these embodiments. Unless otherwise specified, the reagents, methods, and equipment used in this application are all conventional reagents, methods, and equipment in this technical field.

[0068] Example 1

[0069] This embodiment provides a secondary battery, the preparation method of which includes the following steps:

[0070] Preparation of positive electrode sheet

[0071] The positive electrode material LiFePO4, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 95:3:2. N-methylpyrrolidone (NMP) solvent was added, and the mixture was stirred under vacuum to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated on both sides of the positive electrode current collector aluminum foil, dried at room temperature, and then transferred to an oven for further drying. Finally, the positive electrode sheet was obtained by rolling and cutting.

[0072] Negative electrode preparation

[0073] a. Preparation of negative electrode materials

[0074] Place the graphite in the crusher, adjust the main power to 350kW and the air intake to 55m³ / h. 2 The feed rate is 1200 kg / h, the grading frequency is 62 Hz, the crushing time is 30 min, the crushed material is placed in a shaping machine, the feeding frequency is 58 Hz, the grading frequency is 43 Hz, the grinding disc spacing is 120 μm, the shaping speed is 750 rpm, the shaping time is 20 min, 7.6% PVP is added to the shaped material and mixed in a fusion machine for 35 min, the temperature is raised to 1240℃ at a heating rate of 1℃ / min, and held for 3 h. After the calcined material is cooled, it is dispersed in a VC mixer at a speed of 60 rpm for 30 min, and then screened using a 350 mesh screen. The undersize material is demagnetized to obtain the target carbon-containing anode material. The relevant physical properties of the anode material are detailed in Table 1.

[0075] b. Preparation of negative electrode sheet

[0076] The negative electrode material prepared in step a, conductive carbon black, binder styrene-butadiene rubber, and dispersant sodium carboxymethyl cellulose were mixed in a mass ratio of 96:1:1.5:1.5. Deionized water was added as solvent, and the mixture was stirred under vacuum to obtain a negative electrode slurry. The negative electrode slurry was uniformly coated on both sides of the negative electrode current collector copper foil, dried at room temperature, and then transferred to an oven for further drying. After rolling and cutting, the negative electrode sheet was obtained.

[0077] Preparation of electrolyte

[0078] Lithium hexafluorophosphate was dissolved in an organic solvent (ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) = 1:1:1 volume ratio) to obtain an electrolyte with a lithium ion concentration of 1M.

[0079] Secondary battery assembly

[0080] The negative electrode sheet was die-cut into a size of 45mm×58mm using a die-cutting machine, and the positive electrode sheet was die-cut into a size of 43mm×56mm using a die-cutting machine; polypropylene (celgard2500, purchased from Celgard, USA) was used as the separator.

[0081] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes. They are then wound into a bare cell and packed into a soft-pack casing. After processes such as top-side sealing, electrolyte injection, formation, and sorting, a lithium-ion secondary battery (soft-pack battery) is obtained.

[0082] Examples 2-16 and Comparative Examples 1-6

[0083] The main difference between Examples 2-16 and Comparative Examples 1-6 and Example 1 is that the process parameters such as crushing, shaping, and coating amount in the preparation method of the negative electrode material are adjusted so that the prepared negative electrode material has the physical properties as shown in Table 1.

[0084] Table 1

[0085] The electrochemical performance of the above-mentioned secondary batteries was tested as follows:

[0086] The specific performance tests for the secondary batteries are as follows:

[0087] (1) Rate performance: At room temperature (25±2℃), the battery with SOC=0% state of charge was charged to 3.65V at a current density of 0.33C, and the capacity was recorded as C1; then at room temperature, the battery with SOC=0% state of charge was charged to 3.65V at a current density of 4C, and the capacity was recorded as C2; the capacity retention rate (%) was calculated as C2 / C1×100%, which was used as the test index for fast charging performance. The test results are detailed in Table 2.

[0088] (2) Cycling performance: At 25±2℃, the battery was charged and discharged at a rate of 1C / 1C within the range of 2.5 to 3.65V. The discharge specific capacity of the battery in the first cycle and the discharge specific capacity after 1000 cycles were recorded. The capacity retention rate after 1000 cycles was calculated as: discharge specific capacity of 1000 cycles / discharge specific capacity in the first cycle × 100%.

[0089] Table 2

[0090] The results above show that:

[0091] This application achieves excellent fast-charging performance and cycle stability by controlling the particle size, specific surface area, powder compaction density, and OI value of the carbon-based anode material to satisfy certain relationships.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A negative electrode material, comprising a carbonaceous material, wherein, The negative electrode material satisfies the following relationship: 0.4≤D V 50×S / [∣P-OI / 4.8∣×210]≤1.1 In the formula, D V 50 μm represents the particle size corresponding to a cumulative volume percentage of 50% for the negative electrode material; Sm 2 / g represents the specific surface area of ​​the negative electrode material; P g / cm 3 This indicates the compaction density of the negative electrode material under a pressure of 5 tons (T); OI represents the graphite orientation degree of the negative electrode material, which is the ratio of the peak intensity of the (004) diffraction peak to the (110) diffraction peak in the XRD pattern.

2. The negative electrode material according to claim 1, wherein, The negative electrode material satisfies: 0.9 ≤ D V 50×S / [∣P-OI / 4.8∣×210]≤1.

02.

3. The negative electrode material according to any one of claims 1-2, wherein, The negative electrode material satisfies at least one of the following conditions (i) to (iii): (i) The powder compaction density P of the negative electrode material under 5T pressure P g / cm³ 3 Satisfies: P < 1.7; (ii) The specific surface area Sm of the negative electrode material 2 / g satisfies: 0.6≤S≤5; (iii) The D V 50μm satisfies: 11≤D V 50≤20.

4. The negative electrode material according to claim 3, wherein, The powder compaction density of the negative electrode material under 5T pressure is P g / cm³. 3 It satisfies: 1.61≤P<1.

70.

5. The negative electrode material according to claim 3, wherein, The specific surface area Sm of the negative electrode material 2 / g satisfies: 1.89≤S≤3.

54.

6. The negative electrode material according to any one of claims 1-5, wherein, The particle size distribution of the negative electrode material satisfies: 1.0 ≤ (D V 90-D V 10) / D V 50≤2.1 D V 90μm represents the particle size corresponding to a cumulative volume percentage of 90% for the negative electrode material; D V 10 μm represents the particle size corresponding to a cumulative volume percentage of 10% for the negative electrode material; D V 50 μm represents the particle size corresponding to a cumulative volume percentage of 50% for the negative electrode material.

7. The negative electrode material according to claim 6, wherein, 4μm≤D V 10μm≤15μm。 8. The negative electrode material according to claim 6, wherein, 20μm≤D V 90μm≤45μm。 9. The negative electrode material according to any one of claims 1-8, wherein, The compacted density of the negative electrode material powder satisfies: P g / cm³ 3 -Ag / cm 3 ≥0.2g / cm 3 P g / cm 3 This indicates the compaction density of the negative electrode material under 5T pressure; Ag / cm 3 This indicates the compaction density of the negative electrode material under a pressure of 2T.

10. The negative electrode material according to claim 9, wherein, The compacted density of the negative electrode material powder meets the following requirement: 0.20 g / cm³. 3 ≤P g / cm 3 -Ag / cm 3 ≤0.23g / cm 3 .

11. The negative electrode material according to claim 9, wherein, The negative electrode material satisfies the following condition: 1.35 g / cm³ 3 ≤Ag / cm 3 ≤1.50g / cm 3 .

12. The negative electrode material according to any one of claims 1-11, wherein, The negative electrode material satisfies at least one of the following conditions (iv) to (v): (iv) The graphitization degree of the negative electrode material is 92% to 96%; (v) The OI value of the powder of the negative electrode material is 1 to 12.

13. The negative electrode material according to any one of claims 1-12, wherein, The specific capacity of the negative electrode material is 340 mAh / g to 360 mAh / g.

14. A secondary battery, comprising a positive electrode, an electrolyte, a separator, and a negative electrode, wherein, The negative electrode sheet includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, wherein the negative electrode material layer contains the negative electrode material according to any one of claims 1 to 13.

15. An electrical device comprising the secondary battery of claim 14.

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