Graphite negative electrode particles, preparation method therefor, battery, and energy storage apparatus

Abstract

The present application provides graphite negative electrode particles, a preparation method therefor, a battery, and an energy storage apparatus. The graphite negative electrode particles in the embodiments of the present application comprise multiple layers stacked sequentially, the graphite negative electrode particles are also provided with multiple openings, each of the openings penetrates some of the multiple layers, and the sizes of the openings gradually decrease from the mouths of the openings to the bottom walls of the openings.

Description

Graphite anode particles, their preparation methods, batteries and energy storage devices

[0001] This application claims priority to Chinese Patent Application No. 202410976853.2, filed on July 19, 2024, entitled "Graphite Anode Particles, Preparation Method Thereof, Battery and Energy Storage Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of energy storage, specifically to a graphite anode particle, its preparation method, battery, and energy storage device. Background Technology

[0003] The energy efficiency requirements for lithium-ion batteries are becoming increasingly stringent, and improving energy efficiency mainly relies on enhancing the kinetics of the electrochemical system. Graphite is commonly used as the anode material in lithium-ion batteries; however, the cycle performance of existing graphite materials still needs improvement. Summary of the Invention

[0004] This application provides a graphite anode particle with high cycle performance.

[0005] In a first aspect, embodiments of this application provide a graphite anode particle, the graphite anode particle comprising multiple layers of sheets stacked sequentially, the graphite anode particle also having multiple openings, each opening penetrating a portion of the multiple layers of sheets, the size of the opening gradually decreasing from the opening of the opening to the bottom wall of the opening.

[0006] Secondly, embodiments of this application also provide a method for preparing graphite anode particles, the preparation method comprising:

[0007] Provide graphite matrix particles; and

[0008] Carboxymethyl cellulose salt is added to the graphite matrix particles and then heat-treated to obtain the graphite anode particles. The graphite anode particles comprise multiple layers of sheets stacked sequentially. The graphite anode particles also have multiple openings, each of which penetrates a portion of the multiple layers of sheets. The size of the opening gradually decreases from the opening to the bottom wall of the opening.

[0009] Thirdly, embodiments of this application also provide a battery, which includes:

[0010] Electrolyte;

[0011] Positive electrode sheet;

[0012] A separator, the separator being located on one side of the positive electrode, and

[0013] A negative electrode sheet is disposed on the side of the separator opposite to the positive electrode sheet. The negative electrode sheet includes a negative active layer, which includes the graphite negative electrode particles described in the embodiments of this application.

[0014] Fourthly, embodiments of this application also provide an energy storage device, which includes:

[0015] Box; and

[0016] Multiple batteries as described in the embodiments of this application are housed within the casing.

[0017] The graphite anode particles of this application embodiment include multiple layers of sheets stacked sequentially. Each graphite anode particle also has multiple openings, each opening penetrating a portion of one of the multiple layers. The size of the opening gradually decreases from the opening to the bottom wall of the opening. The multi-layered stepped-pore structure of the graphite anode particles of this application, with its smaller inner and larger outer openings, facilitates electrolyte wetting, forming small "reservoirs." Even in high-density negative electrode systems, because the graphite anode particles themselves have a certain electrolyte storage function, when applied to batteries, during the later stages of battery cycling, the electrolyte "reservoirs" formed on the graphite anode particles are not affected by the reverse pressure of the battery casing caused by the expansion of the negative electrode, thus improving the cycle performance of the graphite anode particles. Furthermore, the openings do not excessively affect the specific capacity of the graphite anode particles, resulting in high specific capacity. Furthermore, the openings that penetrate multiple layers can increase the active sites of graphite anode particles, increase the number of entry points for active lithium to intercalate between graphite layers, significantly increase the lithium ion insertion / extraction rate, shorten the lithium ion insertion / extraction path, reduce the electrochemical polarization of graphite anode particles, and improve the kinetic and cycle performance of graphite anode particles. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 is a scanning electron microscope image of graphite negative electrode particles according to an embodiment of this application, wherein the magnification is 5000x.

[0020] Figure 2 is a scanning electron microscope image of graphite negative electrode particles according to an embodiment of this application, wherein the magnification is 20,000 times.

[0021] Figure 3 is a schematic flowchart of a method for preparing graphite anode particles according to an embodiment of this application.

[0022] Figure 4 is a schematic flowchart of a method for preparing graphite matrix particles according to an embodiment of this application.

[0023] Figure 5 is a schematic diagram of the structure of a battery according to an embodiment of this application.

[0024] Figure 6 is a cross-sectional view of a battery according to an embodiment of this application along the AA direction in Figure 5.

[0025] Figure 7 is a schematic diagram of the structure of a negative electrode sheet according to an embodiment of this application.

[0026] Figure 8 is a schematic diagram of the structure of a positive electrode sheet according to an embodiment of this application.

[0027] Figure 9 is a scanning electron microscope image of the graphite anode particles of Comparative Example 3 of this application.

[0028] Figure 10 is a schematic diagram of the structure of an energy storage device according to an embodiment of this application.

[0029] Explanation of reference numerals in the attached drawings: 100-graphite negative electrode particles, 10-sheets, 20-apertures, 300-battery, 310-positive electrode sheet, 311-positive current collector, 312-positive active layer, 320-separator, 330-negative electrode sheet, 331-negative current collector, 332-negative active layer, 340-shell, 350-end cap assembly, 400-energy storage device, 410-box. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0031] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0032] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0033] It should be noted that, for ease of explanation, the same reference numerals denote the same components in the embodiments of this application, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0034] The energy efficiency requirements for lithium-ion batteries are becoming increasingly stringent, and improving energy efficiency mainly relies on enhancing the kinetics of the electrochemical system. Graphite is commonly used as the anode material in lithium-ion batteries; however, the cycle performance of existing graphite materials still needs improvement.

[0035] Please refer to Figures 1 and 2. This application embodiment provides a graphite negative electrode particle 100, which includes multiple layers of sheets 10 stacked sequentially. The graphite negative electrode particle 100 also has a plurality of openings 20, each of which penetrates a portion of the multiple layers of sheets 10. The size of the opening 20 gradually decreases from the opening of the opening 20 toward the bottom wall of the opening 20.

[0036] The graphite anode particles 100 of this application embodiment can be used as, but are not limited to, as the anode active material of a lithium-ion battery. The battery also includes an electrolyte, in which the anode sheet is immersed.

[0037] It should be noted that "opening 20" refers to a pore that penetrates the surface of the graphite negative electrode particle 100 or is located on the surface of the graphite negative electrode particle 100. "Opening 20" is relative to pores located inside the graphite negative electrode particle 100 (i.e., closed pores). "Opening" refers to the part of the opening 20 that is close to the surface of the graphite negative electrode particle 100.

[0038] Understandably, each of the openings 20 is formed by multiple layers of sheets 10. From the opening of the opening 20 toward the bottom wall of the opening 20, the multiple layers of sheets 10 that form the opening 20 gradually expand outward toward the opening 20, so that each opening 20 forms a structure similar to an inverted "tower".

[0039] It can also be understood that the aperture of the opening 20 gradually increases from the inside of the graphite negative electrode particle 100 to the outside of the graphite negative electrode particle 100.

[0040] It can also be understood that the multilayer sheets 10 surrounding the opening 20 form a stepped structure, that is, the opening 20 is a stepped hole structure.

[0041] The graphite anode particle 100 of this application embodiment includes multiple layers of sheets 10 stacked sequentially. The graphite anode particle 100 also has a plurality of openings 20. Each opening 20 penetrates a portion of the sheets 10 in the multiple layers of sheets 10. The size of the opening 20 gradually decreases from the opening of the opening 20 to the bottom wall of the opening 20. The multi-layered, 10-step porous structure of the graphite anode particles 100 in this application has a shape that is small inside and expands outward. The large openings on the outer layer facilitate the wetting of the electrolyte, forming small "reservoirs". Even in a high-density negative electrode system, because the graphite anode particles 100 themselves have a certain function of storing electrolyte, when applied to a battery, in the middle and later stages of battery cycling, under the reverse extrusion force of the battery casing caused by the expansion of the negative electrode, the electrolyte "reservoirs" formed on the graphite anode particles 100 will not be affected by the extrusion force, thus improving the cycle performance of the graphite anode particles 100. The openings 20 do not excessively affect the specific capacity of the graphite anode particles 100, thereby enabling the graphite anode particles 100 to have a high specific capacity. In addition, the openings 20 penetrating multiple layers 10 can increase the active sites of the graphite anode particles 100, increase the number of entry points for active lithium to intercalate between graphite layers, significantly increase the lithium ion insertion / extraction rate, shorten the lithium ion insertion / extraction path, reduce the electrochemical polarization phenomenon of the graphite anode particles 100, and improve the kinetic performance and cycle performance of the graphite anode particles 100.

[0042] In some embodiments, the average maximum size of the plurality of openings 20 ranges from 0.05 μm ≤ w ≤ 2 μm. It is understood that the average maximum size w of the plurality of openings 20 near the surface of the graphite anode particle 100 ranges from 0.05 μm ≤ w ≤ 2 μm. It is also understood that the average pore size w of the outermost layer (the sheet 10 closest to the surface of the graphite anode particle 100) of the plurality of openings 20 ranges from 0.05 μm ≤ w ≤ 2 μm.

[0043] Specifically, the average value w of the maximum size of the plurality of openings 20 can be, but is not limited to, 0.05μm, 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 1.0μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, etc.

[0044] In this embodiment, if the average value w of the maximum size of the plurality of openings 20 is too small, the amount of electrolyte stored in the openings 20 will be reduced, thus limiting the improvement on the cycle performance of the graphite anode particles 100. As the average value w of the maximum size of the plurality of openings 20 increases, there are more end faces of the graphite anode particles 100 located within the openings 20, resulting in a smaller basal surface area outside the openings 20. Since lithium-ion insertion into the graphite anode particles 100 is mainly interlayer lithium insertion at the basal surface, the amount of lithium inserted decreases, reducing the specific capacity of the graphite anode particles 100. However, the increased electrolyte storage in the openings 20 improves the cycle performance of the graphite anode particles 100. Furthermore, the increased number of active sites on the surface of the graphite anode particles 100 improves their kinetic performance. If the maximum size w of the openings 20 is too large, the specific capacity of the graphite anode particles 100 will decrease excessively, which is detrimental to improving the specific capacity of the graphite anode particles 100.

[0045] Furthermore, the average value w of the maximum size of the plurality of openings 20 is in the range of 0.4μm≤w≤1μm. This allows the graphite anode particles 100 to have a larger electrolyte storage capacity when applied to the battery, thereby improving the cycle capacity retention rate of the graphite anode particles 100. At the same time, it also allows the graphite anode particles 100 to have a more suitable proportion of basal surface, thus achieving a higher specific capacity.

[0046] In some embodiments, the depth h of the opening 20 is in the range of 1nm ≤ h ≤ 800nm.

[0047] Specifically, the depth h of the opening 20 can be, but is not limited to, 1nm, 3nm, 5nm, 10nm, 15nm, 20nm, 30nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, etc.

[0048] In this embodiment, if the depth h of the opening 20 is too shallow, the electrolyte storage capacity of the opening 20 is reduced, thus limiting the improvement in the cycle performance of the graphite anode particles 100. As the depth h of the opening 20 increases, the electrolyte storage capacity gradually increases, thereby improving the cycle performance of the graphite anode particles 100. Furthermore, the lithium-ion transport path becomes shorter, allowing it to enter the graphite interlayer of the graphite anode particles 100 more quickly, thereby improving the kinetic performance of the graphite anode particles 100. When the depth h of the opening 20 is in the range of 1 nm ≤ h ≤ 800 nm, the graphite anode particles 100 can store more electrolyte when used in batteries, thus better improving the cycle capacity retention rate of the graphite anode particles 100, while also exhibiting higher specific capacity and higher kinetic performance.

[0049] In some embodiments, the ratio A of the total area of ​​the openings 20 penetrating three or more layers 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite negative electrode particle 100 is in the range of 5% ≤ A ≤ 50%.

[0050] Specifically, the ratio A of the total area of ​​the openings 20 penetrating three or more layers 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite negative electrode particle 100 can be, but is not limited to, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc.

[0051] In this embodiment, if the ratio A of the total area of ​​the openings 20 penetrating three or more layers 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite anode particle 100 is too small, the graphite anode can store too little electrolyte, resulting in limited improvement in the cycle performance of the graphite anode particle 100. As the ratio A of the total area of ​​the openings 20 penetrating three or more layers 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite anode particle 100 increases, the area of ​​the openings 20 increases, reducing the lithium insertion / extraction polarization phenomenon and improving the cycle performance of the graphite anode particle 100. However, when the ratio A of the total area of ​​the openings 20 penetrating three or more layers 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite anode particle 100 is too large, the specific capacity of the graphite anode particle 100 is reduced due to the decrease in the proportion of the base area. Furthermore, it increases the side reactions of the graphite anode particle 100, which also reduces the cycle capacity retention rate. When the ratio A of the total area of ​​the openings 20 penetrating three or more layers 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite anode particle 100 is in the range of 5% ≤ A ≤ 50%, the graphite anode particle 100 can have both a high cycle capacity retention rate and a high specific capacity.

[0052] Furthermore, the ratio A of the total area of ​​the openings 20 penetrating three or more layers 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite anode particle 100 is in the range of 10% ≤ A ≤ 30%. This allows the graphite anode particle 100 to have both a high cycle capacity retention rate and a high specific capacity.

[0053] In some embodiments, the surface defect degree ID / IG of the graphite anode particles 100 is in the range of 0.62≤ID / IG≤1.71, where ID is the intensity of the D peak in the Raman spectrum of the graphite anode particles 100, and IG is the intensity of the G peak in the Raman spectrum of the graphite anode particles 100.

[0054] Specifically, the surface defect degree ID / IG of the graphite anode particles 100 can be, but is not limited to, 0.62, 0.65, 0.68, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.71, etc.

[0055] In this embodiment, if the surface defect degree ID / IG of the graphite anode particles 100 is too low, the number of active sites on the surface of the graphite anode particles 100 will be too small, reducing the kinetic performance of the graphite anode particles 100. As the surface defect degree ID / IG of the graphite anode particles 100 increases, the specific capacity of the graphite anode particles 100 slightly increases. This is due to the lithium intercalation mechanism caused by defects, which helps with lithium storage and thus improves the specific capacity of the graphite anode particles 100. However, the increase in defects will also increase the side reactions of the graphite anode particles 100, thereby consuming more film-forming additives in the electrolyte. Therefore, it will worsen the cycling performance and reduce the cycle capacity retention rate of the graphite anode particles 100. Therefore, when the surface defect degree ID / IG of the graphite anode particles 100 is in the range of 0.62 ≤ ID / IG ≤ 1.71, the graphite anode particles 100 can have both high cycle performance and high specific capacity and kinetic performance.

[0056] In some embodiments, the particle size distribution of the graphite anode particles 100 satisfies: 1.1 ≤ (Dv90 - Dv10) / Dv50 ≤ 1.5, where Dv10 is the particle size corresponding to a cumulative particle size distribution percentage of 10% in the volume distribution of the graphite anode particles 100, Dv50 is the particle size corresponding to a cumulative particle size distribution percentage of 50% in the volume distribution of the graphite anode particles 100, and Dv90 is the particle size corresponding to a cumulative particle size distribution percentage of 90% in the volume distribution of the graphite anode particles 100.

[0057] Specifically, the (Dv90-Dv10) / Dv50 of the graphite negative electrode particles 100 can be, but is not limited to, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, etc.

[0058] It should be noted that the smaller (Dv90-Dv10) / Dv50 is, the narrower the particle size distribution of the graphite anode particles 100; the larger (Dv90-Dv10) / Dv50 is, the wider the particle size distribution of the graphite anode particles 100.

[0059] Optionally, the Dv50 of the graphite anode particles 100 is in the range of 9μm≤Dv50≤18μm. Specifically, the Dv50 of the graphite anode particles 100 can be, but is not limited to, 9μm, 10μm, 12μm, 14μm, 16μm, 17μm, 18μm, etc.

[0060] In this embodiment, the narrower the particle size distribution of the graphite negative electrode particles 100, the more uniform the pores within the negative electrode active layer after the graphite negative electrode particles 100 are formed into the negative electrode active layer of the negative electrode sheet. This is beneficial for the electrolyte to wet the negative electrode active layer, thereby improving the cycle performance of the negative electrode sheet using the graphite negative electrode particles 100. However, when the graphite negative electrode particles 100 are formed into the negative electrode active layer of the negative electrode sheet, the porosity of the negative electrode sheet increases, and the energy density of the negative electrode sheet decreases. If the particle size distribution of the graphite negative electrode particles 100 is wider, the specific capacity of the graphite negative electrode particles 100 increases slightly. However, when the graphite negative electrode particles 100 are formed into the negative electrode active layer of the negative electrode sheet, the pores between the graphite negative electrode particles 100 are too small, which can easily cause insufficient electrolyte wetting and reduce the cycle capacity retention rate of the negative electrode sheet. Therefore, when the particle size distribution of the graphite anode particles 100 satisfies: 1.1≤(Dv90-Dv10) / Dv50≤1.5, the graphite anode particles 100 can have both a high cycle capacity retention rate and good wettability and high specific capacity.

[0061] The specific capacity of the graphite anode particles 100 in this application ranges from 330 mAh / g to 345 mAh / g. Specifically, the specific capacity of the graphite anode particles 100 can be, but is not limited to, 330 mAh / g, 333 mAh / g, 335 mAh / g, 338 mAh / g, 340 mAh / g, 343 mAh / g, 345 mAh / g, 348 mAh / g, 342 mAh / g, 345 mAh / g, etc. The graphite anode particles 100 of this application have a high specific capacity.

[0062] Measurements show that the graphite anode particles 100 of this embodiment have a high compaction density, with a compaction density of 1.8 g / cm³ for 5 tons (5t) of powder. 3Up to 1.95 g / cm 3 Specifically, it can be, but is not limited to, 1.8 g / cm³. 3 1.82g / cm 3 1.84 g / cm 3 1.86 g / cm 3 1.88g / cm 3 1.90g / cm 3 1.93g / cm 3 1.95g / cm 3 wait.

[0063] The graphite anode particles 100 of this application embodiment can be prepared by the methods described in the following embodiments of this application. In addition, they can also be prepared by other methods. The preparation methods of this application embodiment are merely one or more preparation methods of the graphite anode particles 100 of this application and should not be construed as limiting the graphite anode particles 100 provided in the embodiments of this application.

[0064] Please refer to Figure 3. This application also provides a method for preparing graphite anode particles 100, the preparation method comprising:

[0065] S201, providing graphite matrix particles; and

[0066] S202, carboxymethyl cellulose salt is added to the graphite matrix particles and heat-treated to obtain the graphite negative electrode particles 100, wherein the graphite negative electrode particles 100 include multiple layers of sheets 10 stacked sequentially, and the graphite negative electrode particles 100 also have a plurality of openings 20, each opening 20 penetrating a portion of the sheets 10 in the multiple layers of sheets 10, and the size of the opening 20 gradually decreases from the opening of the opening 20 to the bottom wall of the opening 20.

[0067] Understandably, after uniformly mixing the graphite matrix particles with carboxymethyl cellulose salt according to a preset mass ratio, heat treatment is performed to obtain the graphite anode particles 100.

[0068] For detailed descriptions of the graphite anode particles 100, the sheets 10, the openings 20, and other aspects, please refer to the descriptions of the corresponding sections in the above embodiments, which will not be repeated here.

[0069] In the preparation method of the graphite negative electrode particles 100 in this application embodiment, carboxymethyl cellulose salt is added to the graphite matrix particles and heat-treated, so that the obtained graphite negative electrode particles 100 have a multilayer sheet structure 10 and a stepped pore structure with the pore size gradually decreasing from the outside to the inside. The multi-layered, 10-step porous structure of the graphite anode particles 100 in this application has a shape that is small inside and expands outward. The large openings on the outer layer facilitate the wetting of the electrolyte, forming small "reservoirs". Even in a high-density negative electrode system, because the graphite anode particles 100 themselves have a certain function of storing electrolyte, when applied to a battery, in the middle and later stages of battery cycling, under the reverse extrusion force of the battery casing caused by the expansion of the negative electrode, the electrolyte "reservoirs" formed on the graphite anode particles 100 will not be affected by the extrusion force, thus improving the cycle performance of the graphite anode particles 100. The openings 20 do not excessively affect the specific capacity of the graphite anode particles 100, thereby enabling the graphite anode particles 100 to have a high specific capacity. In addition, the openings 20 penetrating multiple layers 10 can increase the active sites of the graphite anode particles 100, increase the number of entry points for active lithium to intercalate between graphite layers, significantly increase the lithium ion insertion / extraction rate, shorten the lithium ion insertion / extraction path, reduce the electrochemical polarization phenomenon of the graphite anode particles 100, and improve the kinetic performance and cycle performance of the graphite anode particles 100.

[0070] Please refer to Figure 4. In some embodiments, in S201, the provision of graphite matrix particles includes:

[0071] S2011, providing a carbon source, wherein the mass fraction of volatile matter in the carbon source ranges from 5% to 15%;

[0072] Optionally, the carbon source may be, but is not limited to, at least one of petroleum coke, pitch coke, needle coke, etc.

[0073] Specifically, the mass fraction of volatiles in the carbon source can be, but is not limited to, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc. If the mass fraction of volatiles in the carbon source is too low, the proportion of open pores 20 in the resulting graphite anode particles 100 will be too low, increasing the impedance of the graphite anode particles 100, reducing the kinetic performance of the graphite anode particles 100, and increasing the expansion force of the graphite anode particles 100 during lithium intercalation, thus reducing the cycle performance of the graphite anode particles 100. As the mass fraction of volatiles in the carbon source increases, the number of layers 10 penetrated by the openings 20 increases, which is beneficial to improving the electrolyte storage capacity of the graphite anode particles 100, thereby improving the cycle performance of the graphite anode particles 100. However, if the mass fraction of volatiles in the carbon source is too high, the resulting graphite anode particles 100 will have too many openings 20, reducing the specific capacity of the graphite anode particles 100. In addition, it will increase the side reactions of the graphite anode particles 100, which will also reduce the cycle capacity retention rate of the graphite anode particles 100. When the mass fraction of volatiles in the carbon source is in the range of 5% to 15%, the resulting graphite anode particles 100 can have a more suitable number and depth of openings 20, thereby enabling the graphite anode particles 100 to have both high cycle performance and high kinetic performance.

[0074] S2012, pretreated at a first temperature T1 within the range of 25℃≤T1≤800℃, to obtain intermediate particles; and

[0075] Alternatively, pretreatment can be carried out in a horizontal reactor.

[0076] Understandably, when the first temperature T1 is room temperature or normal temperature, it is equivalent to no pretreatment process; in other words, the pretreatment process may also be omitted.

[0077] Specifically, the pretreatment temperature can be, but is not limited to, 25℃, 30℃, 40℃, 50℃, 100℃, 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, etc.

[0078] Furthermore, the first temperature T1 is in the range of 200℃≤T1≤800℃, which can increase the porosity inside the obtained graphite anode particles 100, thereby reducing the expansion rate of the graphite anode particles 100 during the potential process.

[0079] Optionally, stirring is performed during pretreatment at a speed of 30 r / min to 50 r / min. Specifically, the stirring speed can be, but is not limited to, 30 r / min, 32 r / min, 34 r / min, 36 r / min, 38 r / min, 40 r / min, 42 r / min, 44 r / min, 46 r / min, 48 r / min, 50 r / min, etc. Stirring makes the intermediate particles more uniform in size, which is beneficial for the electrolyte to wet the negative electrode active layer, thereby improving the cycle performance of the negative electrode sheet using the graphite negative electrode particles 100. If the stirring speed is too low, the resulting intermediate particle size distribution will still be large. When the graphite negative electrode particles 100 are made into the negative electrode active layer of the negative electrode sheet, it will not be conducive to the electrolyte to wet the negative electrode active layer, and the improvement of cycle performance will be limited. If the stirring speed is too high, the intermediate particle size distribution will be too small, resulting in a small particle size distribution of the graphite negative electrode particles 100. When the graphite negative electrode particles 100 are made into the negative electrode active layer of the negative electrode sheet, it will increase the porosity of the negative electrode sheet and reduce the energy density of the negative electrode sheet.

[0080] S2013, the intermediate particles are graphitized at a second temperature T2 in the range of 2800℃≤T2≤3500℃ to obtain the graphite matrix particles.

[0081] Specifically, the second temperature T2 can be, but is not limited to, 2800℃, 2900℃, 3000℃, 3050℃, 3100℃, 3150℃, 3200℃, 3250℃, 3300℃, 3350℃, 3400℃, 3450℃, 3500℃, etc. If the graphitization temperature is too low, the graphitization degree of the graphite anode particles 100 will be reduced, the conductivity of the graphite anode particles 100 will be reduced, and thus the kinetic performance of the graphite anode particles 100 will be reduced; if the graphitization temperature is too high, the preparation cost of the graphite anode particles 100 will be increased.

[0082] In some embodiments, prior to the pretreatment, providing the graphite matrix particles further includes:

[0083] The carbon source is sieved to obtain precursor particles, wherein the particle size distribution of the precursor particles satisfies: 1.1≤(Dv'90-Dv'10) / Dv'50≤1.5, where Dv'10 is the particle size corresponding to a cumulative particle size distribution percentage of 10% in the volume distribution of the precursor particles, Dv'50 is the particle size corresponding to a cumulative particle size distribution percentage of 50% in the volume distribution of the precursor particles, and Dv'90 is the particle size corresponding to a cumulative particle size distribution percentage of 90% in the volume distribution of the precursor particles.

[0084] Optionally, the carbon source is coarsely crushed in a jaw crusher and then finely ground in a flow mill, followed by screening to obtain precursor particles with a particle size distribution of 1.1≤(Dv'90-Dv'10) / Dv'50≤1.5.

[0085] Specifically, the (Dv'90-Dv'10) / Dv'50 of the precursor particles can be, but is not limited to, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, etc.

[0086] The smaller the (Dv'90-Dv'10) / Dv'50 of the precursor particles, the narrower the particle size distribution of the resulting graphite anode particles 100. This results in a more uniform pore size distribution within the active layer of the anode sheet, which is beneficial for electrolyte wetting and thus improves the cycle performance of the anode sheet using the graphite anode particles 100. However, when the graphite anode particles 100 are used to form the active layer of the anode sheet, it increases the... The porosity of the negative electrode sheet is reduced, thus lowering its energy density. A larger (Dv'90-Dv'10) / Dv'50 ratio of the precursor particles results in a wider particle size distribution of the obtained graphite negative electrode particles 100, leading to a slight increase in the specific capacity. However, when the graphite negative electrode particles 100 are used as the negative electrode active layer of the negative electrode sheet, the small pores between the particles can easily cause insufficient electrolyte wetting, reducing the cycle capacity retention rate of the negative electrode sheet. Therefore, in this embodiment, the carbon source is ground into fine particles and then sieved to obtain precursor particles with a particle size distribution of 1.1≤(Dv'90-Dv'10) / Dv'50≤1.5. This ensures that the particle size distribution of the obtained graphite negative electrode particles 100 is within a suitable range, resulting in graphite negative electrode particles 100 with a high cycle capacity retention rate, good wettability, and a high specific capacity.

[0087] In some embodiments, the carboxymethyl cellulose salt includes at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, and potassium carboxymethyl cellulose, wherein the mass of the carboxymethyl cellulose salt is 0.1% to 5% of the mass of the graphite matrix particles.

[0088] Specifically, the mass of the carboxymethyl cellulose salt is 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., of the mass of the graphite matrix particles.

[0089] In this embodiment, if the amount of carboxymethyl cellulose salt added is too small, the porous sheet structure 10 on the surface of the graphite anode particle 100 will not be obvious, and the improvement on the cycle capacity retention rate of the battery using the graphite anode particle 100 will be limited. As the amount of carboxymethyl cellulose salt added increases, the number of through-sheets 10 with formed openings 20 increases, and the number of openings 20 also increases, thereby increasing the "reservoir" capacity of the graphite anode particle 100 for the electrolyte, and gradually increasing the cycle capacity retention rate of the battery using the graphite anode particle 100. However, if the amount of carboxymethyl cellulose salt added is too large, the graphite anode particle 100 will have too many defects, resulting in too many side reactions and excessive consumption of active lithium, which will worsen the cycle capacity retention rate of the battery using the graphite anode particle 100. When the mass of the carboxymethyl cellulose salt is 0.1% to 5% of the mass of the graphite matrix particles, the surface of the obtained graphite anode particles 100 can have more openings 20 and sheets 10, and the number of sheets 10 penetrated by the openings 20 is relatively large, thereby giving the openings 20 a better ability to store electrolyte. In addition, the obtained graphite anode particles 100 can also have a more suitable degree of defect, and will not have too many side reactions, thereby giving the battery using the graphite anode particles 100 a higher cycle capacity retention rate.

[0090] In some embodiments, in S202, the heat treatment includes performing the heat treatment at a temperature T3 in the range of 200°C ≤ T3 ≤ 650°C in an oxygen atmosphere.

[0091] Specifically, the heat treatment temperature T3 can be, but is not limited to, 200℃, 230℃, 250℃, 280℃, 300℃, 330℃, 350℃, 380℃, 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, 630℃, 650℃, etc.

[0092] In this embodiment, if the heat treatment temperature T3 is too low, the resulting graphite anode particles 100 will have too few openings 20 on their surface, and the number of layers penetrated by the openings 20 will be too small, resulting in limited improvement in the cycle capacity retention rate of the battery using the graphite anode particles 100. If the heat treatment temperature T3 is too high, too many openings 20 will be formed, and the number of layers penetrated by the openings 20 will be too large, which will increase the side reactions of the graphite anode particles 100, excessively consuming active lithium, and thus reducing the cycle capacity retention rate of the battery using the graphite anode particles 100. When the heat treatment temperature T3 is in the range of 200℃≤T3≤650℃, the surface of the resulting graphite anode particles 100 can have a suitable number of openings 20, and the proportion of layers penetrated by the openings 20 being three or more layers is within a suitable range, thereby enabling the battery using the graphite anode particles 100 to have a high cycle capacity retention rate.

[0093] Furthermore, the heat treatment temperature T3 is in the range of 300℃≤T3≤600℃. This allows the surface of the obtained graphite anode particles 100 to have a suitable number of openings 20, and the proportion of the number of layers 10 penetrated by the openings 20 being three or more is within a more suitable range, thereby enabling the battery of the graphite anode particles 100 to have a higher cycle capacity retention rate.

[0094] Furthermore, the heat treatment temperature T3 is in the range of 400℃≤T3≤550℃. This allows the surface of the obtained graphite anode particles 100 to have a suitable number of openings 20, and the proportion of the number of layers 10 penetrated by the openings 20 being three or more is within a more suitable range, thereby enabling the battery of the graphite anode particles 100 to have a higher cycle capacity retention rate.

[0095] Please refer to Figures 5 to 7. This application embodiment also provides a battery 300, which includes an electrolyte, a positive electrode 310, a separator 320, and a negative electrode 330. The separator 320 is located on one side of the positive electrode 310, and the negative electrode 330 is disposed on the side of the separator 320 opposite to the positive electrode 310. The negative electrode 330 includes a negative electrode active layer 332, and the negative electrode active layer 332 includes the graphite negative electrode particles 100 described in this application embodiment.

[0096] Understandably, the positive electrode 310, the separator 320, and the negative electrode 330 are all at least partially immersed in the electrolyte.

[0097] Understandably, the positive electrode 310, the separator 320, and the negative electrode 330 are sequentially stacked to form an electrode assembly. The electrode assembly can be, but is not limited to, a wound structure, a stacked structure, etc., and this application does not specifically limit it in this regard.

[0098] Optionally, the negative electrode 330 further includes a negative electrode current collector 331, and the negative electrode active layer 332 is disposed on the surface of the negative electrode current collector 331. It can be understood that the negative electrode active layer 332 may cover one surface or both opposite surfaces of the negative electrode current collector 331.

[0099] Optionally, the negative electrode current collector 331 can be, but is not limited to, a copper sheet.

[0100] Optionally, the negative electrode active layer 332 further includes a negative electrode conductive agent, a negative electrode binder, and a negative electrode thickener.

[0101] Referring to Figure 8, optionally, the positive electrode 310 includes a positive current collector 311 and a positive active layer 312, wherein the positive active layer 312 is disposed on the surface of the positive current collector 311. It can be understood that the positive active layer 312 may cover one surface or both opposite surfaces of the positive current collector 311.

[0102] Optionally, the positive current collector 311 can be, but is not limited to, an aluminum sheet.

[0103] Optionally, the positive electrode active layer 312 includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a positive electrode thickener.

[0104] Optionally, the positive electrode active material can be, but is not limited to, lithium iron phosphate.

[0105] Optionally, the diaphragm 320 can be, but is not limited to, at least one of polypropylene membrane (PP membrane), polyethylene membrane (PE membrane), ceramic diaphragm 320, etc.

[0106] Optionally, the battery 300 further includes a housing 340 and an end cap assembly 350, the housing 340 and the end cap assembly 350 forming a closed receiving cavity for housing the electrolyte, the positive electrode 310, the separator 320, and the negative electrode 330. Understandably, the end cap assembly 350 electrically connects the positive electrode 310 and the negative electrode 330, respectively, leading out the positive electrode 310 and the negative electrode 330 for electrical connection to external devices or other batteries 300.

[0107] After the battery of this application has been used for a period of time, the graphite negative electrode particles 100 can be recycled by the following steps: (1) Disassemble the battery after it is fully loaded and remove the negative electrode plate; (2) Soak it in dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) or other organic solvents for 24 hours; (3) Place it in a drying oven and bake it at 80°C to 100°C for 24 to 48 hours; (4) Take it out and place it in a muffle furnace and heat it for 6 to 10 hours to recover the graphite negative electrode particles 100.

[0108] The graphite anode particles 100 and battery 300 of this application will be further described below through specific embodiments.

[0109] Examples 1 to 19, Comparative Examples 1 to 9

[0110] The graphite anode particles 100 in this embodiment are prepared through the following steps:

[0111] (1) Petroleum coke is provided as a carbon source. The petroleum coke is coarsely crushed by a jaw crusher and then ground into fine powder by an air jet mill. The content of volatile matter in petroleum coke in each embodiment and comparative example is shown in Table 1 below.

[0112] (2) The carbon source particles that have been ground into fine powder are sieved to obtain precursor particles. The particle size distribution of the precursor particles in each embodiment and comparative example is shown in Table 1 below.

[0113] (3) Graphitization was carried out in a graphite furnace at a temperature of 3100℃ to obtain graphite matrix particles; and

[0114] (4) Sodium carboxymethyl cellulose was added to the graphite matrix particles and mixed evenly. The mixture was then heat-treated in an oxygen atmosphere to obtain graphite anode particles 100. The amount of sodium carboxymethyl cellulose added and the heat treatment temperature of each embodiment and comparative example are shown in Table 1 below. The scanning electron microscope images of the graphite anode particles 100 obtained in Example 3 are shown in Figures 1 and 2.

[0115] Example 20

[0116] The difference between this embodiment and Embodiment 3 is that the carboxymethyl cellulose salt in this application is lithium carboxymethyl cellulose.

[0117] Example 21

[0118] The difference between this embodiment and Embodiment 3 is that the carboxymethyl cellulose salt in this application is potassium carboxymethyl cellulose.

[0119] Example 22

[0120] The difference between this embodiment and Embodiment 3 is that, before graphitization, the precursor particles of this application are heat-treated at a first temperature T1 of 600°C and the stirring speed is 40 r / min.

[0121] Example 23

[0122] The difference between this embodiment and Embodiment 3 is that, before graphitization, the precursor particles of this application are heat-treated at a first temperature T1 of 200°C and the stirring speed is 40 r / min.

[0123] Example 24

[0124] The difference between this embodiment and Embodiment 3 is that, before graphitization, the precursor particles of this application are heat-treated at a first temperature T1 of 100°C and the stirring speed is 40 r / min.

[0125] The graphite negative electrode particles 100 of each embodiment and comparative example are assembled into a battery 300: negative electrode sheets 330 are prepared by using the graphite negative electrode particles 100 prepared by each embodiment and comparative example. The negative electrode sheet 330, polypropylene separator 320, lithium iron phosphate positive electrode sheet 310 and lithium hexafluorophosphate electrolyte with a concentration of 1 mol / L are assembled into a square battery 300.

[0126] Various performance tests were conducted on the graphite anode particles 100 and the assembled battery 300 of each embodiment and comparative example. The test results are shown in Table 2 below.

[0127] (1) Scanning electron microscope (SEM) test: used to measure the average value w of the maximum size of the opening 20 and the ratio A of the total area of ​​the opening 20 penetrating three or more layers of sheet 10 to the total area of ​​the plurality of openings 20 on the surface of the graphite negative electrode particle 100.

[0128] (2) ID / IG test: Raman spectroscopy was used for measurement.

[0129] (3) Specific capacity test: 10 wt% sodium carboxymethyl cellulose binder was fully dissolved in water, and 10 wt% carbon black conductive agent and 80 wt% of the above-prepared graphite negative electrode particles 100 were added and stirred to obtain a uniformly dispersed slurry. The slurry was uniformly coated on the surface of copper foil and then transferred to a vacuum drying oven for complete drying to obtain negative electrode sheet 330. The obtained negative electrode sheet 330 was rolled, then punched, and then weighed. The negative electrode sheet 330 was assembled with electrolyte, polypropylene separator 320, and lithium metal sheet to form a coin cell.

[0130] The button cell battery was left to stand for 4 hours, then discharged at a rate of 0.05C to 0.005V, left to stand for 10 minutes, discharged at a constant current of 0.05mA to 0.005V, left to stand for 10 minutes, discharged at a constant current of 0.01mA to 0.005V, left to stand for 10 minutes, and then charged at a rate of 0.1C to 2V. The above charging and discharging steps were performed three times, and the total capacity during the third discharge process was recorded. The specific capacity of the graphite negative electrode particles 100 is equal to the total capacity during the third discharge process divided by the weight of the graphite negative electrode particles 100.

[0131] (4) Cycle capacity retention test after 500 cycles: Battery 300 was subjected to a charge-discharge cycle test on a charge-discharge tester (Nebula Charge-Discharge Test System-BAT-NEEFLCT-05300-V010) at a test temperature of 25℃. Battery 300 was charged at a constant power of 0.5P to the charging cut-off voltage of 3.65V, and the initial charging capacity was recorded. After the battery 300 was left to stand for 10 minutes, it was discharged at a constant power of 0.5P to the discharging cut-off voltage of 2.5V, and the discharge capacity was recorded. Wherein, P refers to the rated charging or discharging power of the battery, which is the nominal voltage U of the battery multiplied by the current density of 1C. The nominal voltage of the iron phosphate battery is 3.2V, and 0.5P refers to 0.5 times the rated power.

[0132] The formula for calculating the capacity retention rate after 25℃ cycling is: Capacity retention rate after the nth cycle = (Discharge capacity after the nth cycle / Discharge capacity in the first cycle) × 100%.

[0133] Table 1. Process parameters of graphite anode particles 100 in each embodiment and comparative example.

[0134] Table 2 Performance parameters of the graphite anode particles 100 and batteries prepared in each embodiment and comparative example.

[0135] The test results of Comparative Example 1 show that when sodium carboxymethyl cellulose is not added and heat treatment is performed directly, the surface of the obtained graphite anode particles 100 does not have openings 20 composed of layers 10, the surface defect degree ID / IG of the graphite anode particles 100 is small, the specific capacity is relatively low, and the cycle capacity retention rate of the battery 300 made from the graphite anode particles 100 is low. The test results of Examples 1 to 6 show that when sodium carboxymethyl cellulose is added and heat treatment is performed, the surface of the obtained graphite anode particles 100 forms openings 20 that penetrate multiple layers 10. As the amount of sodium carboxymethyl cellulose added increases, the area ratio of the openings 20 penetrating more than three layers 10 of the obtained graphite anode particles 100 gradually increases, the size of the openings 20 on the surface of the graphite anode particles 100 gradually increases, and the surface defect degree ID / IG also gradually increases. Compared to Comparative Example 1 without sodium carboxymethyl cellulose, the specific capacity of the graphite anode particles 100 and the 500-cycle capacity retention of the battery 300 prepared in Examples 1 to 6 all increased. However, as the amount of sodium carboxymethyl cellulose added gradually increased, the specific capacity of the graphite anode particles 100 gradually decreased, while the cycle capacity retention gradually increased. The test results of Comparative Example 2 show that when the amount of sodium carboxymethyl cellulose added is too high, the opening size 20 of the prepared graphite anode particles 100 is too large, and the surface defects are too large. This results in a decrease in the specific capacity of the graphite anode particles 100 and a decrease in the 500-cycle capacity retention of the battery 300.

[0136] Figure 9 is a scanning electron microscope image of the graphite anode particles 100 prepared in Comparative Example 3. From the test results of Examples 3 and Comparative Example 3 in Tables 1 and 2, it can be seen that when all other conditions are the same and only the heat treatment atmosphere is changed, when the heat treatment is carried out in an oxygen atmosphere (Example 3), the graphite anode particles 100 of this application with openings 20 penetrating multiple layers 10 can be obtained; however, when the heat treatment is carried out in a nitrogen atmosphere, the surface of the obtained graphite anode particles 100 is without pores, as shown in Figure 9. The surface defect degree and specific capacity of the graphite anode particles 100 of Comparative Example 3 are relatively low, and the capacity retention rate after 500 cycles after the battery 300 is made is low.

[0137] The test results from Examples 7 to 11, Comparative Examples 4 and 5 show that when the heat treatment temperature is low (e.g., Comparative Example 4), the resulting graphite anode particles 100 lack the openings 20 described in this application, have low surface defects, and relatively low specific capacity. After being made into a battery 300, the 500-cycle capacity retention rate is also low. When the heat treatment temperature is between 200°C and 650°C, the proportion of openings 20 penetrating more than three layers 10 in the resulting graphite anode particles 100 gradually increases, the size of the openings 20 gradually increases, and the surface defects and specific capacity of the graphite anode particles 100 also gradually increase. After being made into a battery 300, the 500-cycle capacity retention rate of the battery 300 remains in a high range. However, as the heat treatment temperature increases, the cycle capacity retention rate decreases. When the heat treatment temperature is too high, the cycle capacity retention rate is low.

[0138] The test results from Examples 12 to 15, Comparative Examples 6 and 7 show that when the particle size distribution of the precursor particles is small (as in Comparative Example 6), the specific capacity of the graphite anode particles 100 is high, and the 500-cycle capacity retention rate of the battery 300 made from these graphite anode particles 100 is relatively low. As the particle size distribution of the precursor particles gradually increases, the proportion of the openings 20 penetrating three or more layers 10, the size of the openings 20, the surface defects of the graphite anode particles 100, and the specific capacity all gradually increase, and the 500-cycle capacity retention rate of the battery 300 decreases slightly. When the particle size distribution of the precursor particles is too wide (as in Comparative Example 7), the 500-cycle capacity retention rate of the obtained graphite anode particles 100 decreases significantly.

[0139] The test results from Examples 16 to 19, Comparative Examples 8 and 9 show that when the mass fraction of volatiles in the carbon source is too small (as in Comparative Example 8), the proportion of the openings 20 penetrating three or more layers 10 on the graphite anode particles 100 is very small, the size and surface defect of the openings 20 are very small, and the 500-cycle capacity retention rate of the battery 300 is low. As the mass fraction of volatiles in the carbon source gradually increases, the proportion of the openings 20 penetrating three or more layers 10 on the graphite anode particles 100 gradually increases, the size and surface defect of the openings 20 gradually increase, and the specific capacity of the graphite anode particles 100 gradually decreases. However, the 500-cycle capacity retention rate of the battery 300 gradually increases. When the mass fraction of volatiles in the carbon source is too high (as in Comparative Example 9), the proportion of the openings 20 penetrating three or more layers 10 on the graphite anode particles 100 is too high, and the surface defects are too large, resulting in a significant decrease in the 500-cycle capacity retention rate of the battery 300.

[0140] As can be seen from the test results of Examples 3, 20 and 21, during the preparation of graphite anode particles 100, adding different carboxymethyl cellulose salts for heat treatment can result in the graphite anode particles 100 having openings 20 penetrating multiple layers 10 on their surface. The proportion of openings 20 penetrating three or more layers 10 and the degree of surface defects are within a suitable range, and the battery 300 has a high capacity retention rate after 500 cycles.

[0141] The test results from Examples 22 to 24 show that stirring during pretreatment can make the prepared graphite anode particles 100 have a higher specific capacity and a higher cycle capacity retention rate.

[0142] Please refer to Figure 10. This application embodiment also provides an energy storage device 400, which includes a housing 410 and the battery 300 described in this application embodiment, wherein the plurality of batteries 300 are housed in the housing 410.

[0143] The energy storage device 400 of this application can be applied to, but is not limited to, energy storage on the generation side, energy storage on the grid side, and energy storage on the consumption side.

[0144] The term "multiple" refers to two or more.

[0145] Understandably, the multiple batteries 300 of the energy storage device 400 can be connected in parallel, or in series, or partially in parallel and partially in series (in other words, mixed connection). This application does not specifically limit the connection method of the multiple batteries 300 of the same energy storage device 400.

[0146] Understandably, the housing 410 has accommodating cavities in which multiple batteries 300 are housed. In some embodiments, each accommodating cavity houses one battery 300. In other embodiments, each accommodating cavity houses multiple batteries 300.

[0147] Optionally, the energy storage device 400 may include, but is not limited to, battery modules, battery packs, and battery systems. The actual application form of the energy storage device 400 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 400. This application embodiment only uses a multi-cell battery 300 as an example for illustration. When the energy storage device 400 is a single-cell battery 300, the energy storage device 400 may be at least one of cylindrical batteries 300, prismatic batteries 300, etc.

[0148] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various places in the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.

[0149] 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 it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A graphite negative electrode particle, wherein, The graphite negative electrode particle comprises a plurality of stacked layers, and further comprises a plurality of openings, each of which penetrates through part of the plurality of stacked layers, and the size of the opening gradually decreases from the opening to the bottom wall of the opening.

2. The graphite negative electrode particle of claim 1, wherein, The average value w of the maximum size of the plurality of openings ranges from 0.05 μm to 2 μm.

3. The graphite negative electrode particle of claim 1, wherein, The depth h of the opening ranges from 1 nm to 800 nm.

4. The graphite negative electrode particle of claim 1, wherein, The ratio A of the total area of the openings penetrating through three or more layers to the total area of the plurality of openings on the surface of the graphite negative electrode particle ranges from 5% to 50%.

5. The graphite negative electrode particle of claim 1, wherein, The surface defect degree ID / IG of the graphite negative electrode particle ranges from 0.62 to 1.71, where ID is the intensity of the D peak in the Raman spectrum of the graphite negative electrode particle, and IG is the intensity of the G peak in the Raman spectrum of the graphite negative electrode particle.

6. The graphite negative electrode particles according to any one of claims 1 to 5, wherein, The particle size distribution of the graphite negative electrode particle satisfies 1.1≤(Dv90-Dv10) / Dv50≤1.5, where Dv10 is the particle size corresponding to the cumulative particle size distribution percentage of 10% in the volume distribution of the graphite negative electrode particle, Dv50 is the particle size corresponding to the cumulative particle size distribution percentage of 50% in the volume distribution of the graphite negative electrode particle, and Dv90 is the particle size corresponding to the cumulative particle size distribution percentage of 90% in the volume distribution of the graphite negative electrode particle.

7. A method for producing a graphite negative electrode particle, wherein The preparation method comprises: providing graphite base particles; and adding a carboxymethyl cellulose salt to the graphite base particles and performing heat treatment to obtain the graphite negative electrode particle, wherein the graphite negative electrode particle comprises a plurality of stacked layers, and further comprises a plurality of openings, each of which penetrates through part of the plurality of stacked layers, and the size of the opening gradually decreases from the opening to the bottom wall of the opening.

8. The method of producing graphite negative electrode particles according to claim 7, wherein The providing of the graphite base particles comprises: providing a carbon source, wherein the mass fraction of volatile matter in the carbon source ranges from 5% to 15%; performing pretreatment at a first temperature T1 ranging from 25°C to 800°C to obtain intermediate state particles; and performing graphitization treatment on the intermediate state particles at a second temperature T2 ranging from 2800°C to 3500°C to obtain the graphite base particles.

9. The method of producing graphite negative electrode particles according to claim 8, wherein Before the pretreatment, the providing of the graphite base particles further comprises: performing screening treatment on the carbon source to obtain precursor particles, wherein the particle size distribution of the precursor particles satisfies 1.1≤(Dv’90-Dv’10) / Dv’50≤1.5, where Dv’10 is the particle size corresponding to the cumulative particle size distribution percentage of 10% in the volume distribution of the precursor particles, Dv’50 is the particle size corresponding to the cumulative particle size distribution percentage of 50% in the volume distribution of the precursor particles, and Dv’90 is the particle size corresponding to the cumulative particle size distribution percentage of 90% in the volume distribution of the precursor particles.

10. The method of producing graphite negative electrode particles according to claim 7, wherein The carboxymethyl cellulose salt includes at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, and potassium carboxymethyl cellulose, and the mass of the carboxymethyl cellulose salt is 0.1% to 5% of the mass of the graphite matrix particles.

11. The method of producing graphite negative electrode particles according to claim 10, wherein The performing the heat treatment includes: The heat treatment is performed in an oxygen atmosphere at a temperature T3 in a range of 200°C ≤ T3 ≤ 650°C.

12. A battery, wherein, including: an electrolyte; a positive electrode sheet; a separator on one side of the positive electrode sheet, and a negative electrode sheet provided on a side of the separator facing away from the positive electrode sheet, the negative electrode sheet including a negative electrode active layer including the graphite negative electrode particles of any one of claims 1-6.

13. An energy storage device, wherein, including: a case; and a plurality of the batteries of claim 12 housed within the case.

Images