Battery and its manufacturing method, power consumption device

Abstract

This disclosure relates to the battery technology and discloses a battery, a method for manufacturing the same, and a power consumption device. The battery comprises a positive electrode plate, a negative electrode plate, and a separator. The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer located on at least one side of the negative electrode current collector. The negative electrode active material layer comprises a negative electrode active material, which comprises graphite. The proportion of secondary particles in the negative electrode active material is 65% or more. The oil absorption value of the negative electrode active material is 40 mL / 100 g to 65 mL / 100 g. The volume distribution particle size Dv1 of the negative electrode active material is 4 μm to 8 μm.

Description

[Technical Field]

[0001] This disclosure relates to the battery technology field, specifically to batteries, methods for manufacturing the same, and power consumption devices. [Background technology]

[0002] Batteries are widely used in energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, and electric vehicles. As the range of battery applications expands in stages, the market is placing higher demands on battery rate performance. However, current batteries still have many shortcomings in the production and application processes, and there is a need to further improve battery rate performance.

[0003] It should be noted that the above description is merely for the purpose of providing background information related to this application and does not necessarily constitute prior art. [Overview of the Initiative]

[0004] According to a first aspect of this application, the application provides a battery comprising a positive electrode plate, a negative electrode plate, and a separator, wherein the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer located at least on one side of the negative electrode current collector, the negative electrode active material layer includes a negative electrode active material, the negative electrode active material includes graphite, the proportion of secondary particles in the negative electrode active material is 65% or more, the oil absorption value of the negative electrode active material is 40 mL / 100 g to 65 mL / 100 g, and the volume distribution particle size Dv1 of the negative electrode active material is 4 μm to 8 μm. This significantly improves the rate performance and processing performance of the negative electrode active material, contributing to an improvement in the rate performance of the battery.

[0005] In some embodiments, the negative electrode active material satisfies the condition that (Dv90-Dv10) / Dv50 is between 0.8 and 1.2. This improves the kinetic performance of the negative electrode active material.

[0006] In some embodiments, the volume distribution particle size Dv10 of the negative electrode active material is 7 μm-11 μm, and / or the volume distribution particle size Dv90 of the negative electrode active material is 20 μm-30 μm, and / or the volume distribution particle size Dv50 of the negative electrode active material is 12 μm-18 μm. This can further improve the rate performance of the negative electrode active material.

[0007] In some embodiments, the degree of graphitization of the negative electrode active material is 93%-95%. This improves the electronic conductivity of the negative electrode active material.

[0008] In some embodiments, the specific surface area of ​​the negative electrode active material is 2.5 m². 2 / g-3.5m 2 This value is / g. This allows for further improvement of the processing performance of the negative electrode active material.

[0009] In some embodiments, the negative electrode active material further includes a carbon coating layer, the carbon coating layer located on at least a portion of the surface of the secondary particles, the secondary particles being formed by bonding at least two primary particles, and the bonding material including a carbon material. This can improve the conductivity of the negative electrode active material.

[0010] In some embodiments, the porosity of the negative electrode active material layer is 18%-35%. This is advantageous for the penetration of the electrolyte into the negative electrode plate.

[0011] In some embodiments, the compaction density of the negative electrode active material layer is 1.60 g / cm³. 3 -1.75 g / cm³ 3 This is advantageous for the electrolyte to penetrate the negative electrode plate.

[0012] According to a second aspect of this application, this application provides a method for manufacturing the aforementioned battery, comprising: mixing primary graphite particles with an adhesive and performing a first heat treatment to obtain pre-bonded secondary particles; performing a second heat treatment and a first classification treatment on the pre-bonded secondary particles to obtain secondary particles and a negative electrode active material; and placing the negative electrode active material on one side of a negative electrode current collector to obtain a negative electrode plate; and assembling the negative electrode plate, separator, and positive electrode plate to obtain a battery. This makes it possible to obtain a battery with the aforementioned relatively excellent rate performance in a simple manner.

[0013] In some embodiments, providing the graphite primary particles involves crushing and a second classification process on a raw material comprising at least one of petroleum coke and needle coke to obtain the graphite primary particles, wherein the volatile content in the raw material is 4%-7%, and the true density of the raw material is 1.35 g / cm³. 3 -1.50 g / cm³ 3 The system satisfies at least one of the following conditions: the raw material has a sulfur content of 2% or less; the supply frequency of the grinding process is 10Hz-35Hz; and the classification frequency of the second classification process is 30Hz-50Hz. This improves the uniformity of the particle size of the primary graphite particles.

[0014] In some embodiments, the adhesive comprises at least one of asphalt and resin, and the adhesive satisfies at least one of the following conditions: the caulking value of the adhesive is 60%-70%, the mass ratio of the adhesive to the graphite primary particles is (7-10):100, and the particle size of the adhesive is 4μm-8μm. This enhances the adhesive effect of the adhesive on the graphite primary particles.

[0015] In some embodiments, the temperature of the first heat treatment is 600°C-800°C, and the duration of the first heat treatment is 1h-4h. This contributes to improving the pre-adhesion of the adhesive to the primary graphite particles.

[0016] In some embodiments, the temperature of the second heat treatment is 2800°C-3300°C, and the duration of the second heat treatment is 36h-72h. This contributes to improving the adhesion effect of the adhesive to the graphite primary particles.

[0017] In some embodiments, the first classification process satisfies at least one of the following conditions: the screen mesh count of the first classification process is 300-350 mesh; the supply frequency of the first classification process is 4Hz-10Hz; and the classification frequency of the first classification process is 30Hz-50Hz. This allows for the effective removal of fine particles from secondary particles.

[0018] In some embodiments, after obtaining the secondary particles, the secondary particles are further mixed with a liquid phase coating agent and subjected to a third heat treatment to form a carbon coating layer on a portion of the surface of the secondary particles, wherein the liquid phase coating agent includes at least one of asphalt and resin having a viscosity of 500 mPa·s or less. This allows for the formation of a carbon coating layer on the surface of the secondary particles.

[0019] In some embodiments, the mass ratio of the liquid phase coating agent to the secondary particles is (2-10):100, and / or the coking value of the liquid phase coating agent is 40%-70%. This contributes to the negative electrode active material having relatively good rate performance and gram capacity.

[0020] In some embodiments, the temperature of the third heat treatment is 1000°C-1200°C, and the duration of the third heat treatment is 15h-30h. This contributes to the formation of an amorphous carbon coating layer.

[0021] According to a third aspect of this application, the application provides a power consumption device comprising the aforementioned battery and / or a battery manufactured using the aforementioned method. This power consumption device thus possesses all the features and advantages of the aforementioned battery and manufacturing method, which are not described further here. [Brief explanation of the drawing]

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily apparent from the following drawings and associated descriptions of embodiments, hereby [Figure 1] This is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a battery cell according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of this application. [Figure 6] This is a schematic diagram of a power consumption device powered by a battery according to one embodiment of the present application. [Figure 7] This is a scanning electron microscope image of the negative electrode active material of one embodiment of this application. [Figure 8] This is a scanning electron microscope image of the negative electrode active material of one comparative example of this application. [Figure 9] This is a scanning electron microscope image of the negative electrode active material of one embodiment of this application. [Modes for carrying out the invention]

[0023] The embodiments of this application are described in detail below, and examples of these embodiments are shown in the drawings, although unnecessary details may be omitted. For example, detailed explanations of well-known matters and repeated explanations of structures that are actually the same may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0024] Unless otherwise defined, all technical and scientific terms used in this application have meanings that are generally understood by those skilled in the art relating to this application, and the terms used in this application are solely for the purpose of describing specific embodiments and are not intended to limit this application, and unless otherwise stated, the values ​​of each parameter referred to in this application can be measured by various measurement methods commonly used in the art (for example, by testing according to the methods of the embodiments of this application).

[0025] The terms “includes” and “have,” and any variation thereof, in the specification and claims of this application are open expressions, meaning they include the content shown in this application but do not exclude the content of other embodiments.

[0026] In the description of this application, whether or not terms such as “about” or “approximately” are used, all numbers disclosed herein are approximations. The numerical values ​​of each figure may vary by 10% or less, or by a difference that a person skilled in the art would consider reasonable, e.g., 1%, 2%, 3%, 4%, or 5%.

[0027] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the limit value, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also conceivable. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 are all conceivable. In this application, unless otherwise specified, the numerical range “ab” represents an abbreviated expression for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply a shortened representation of combinations of these numbers. Also, expressing a parameter as an integer ≥ 2 is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] In the description of this application, the terms “first” and “second” are for descriptive purposes only and should not be understood as indicating or implying relative importance or the number of technical features being referred to. “First feature” and “second feature” may include one or more such features.

[0029] In the description of this application, “A and / or B” may include any one of the following: A alone, B alone, or A and B, where A and B are used only as examples and may be any technical features connected using “and / or” in this application.

[0030] In this application, the order in which each step is created is not meant to constitute any limitation on the implementation process by strictly executing them in order, and the specific execution order of each step should be determined by its function and possible inherent logic. Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably in order. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, the fact that the method referred to above may further include step (c) means that step (c) may be added to the method in any order, for example the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0032] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0033] Taking graphite as the negative electrode active material as an example, if graphite is a secondary particle, the secondary particle is isotropic and therefore has a relatively large number of lithium ion transport channels. This effectively increases the lithium ion intercalation and deintercalation inlets of the negative electrode active material, improves the lithium ion interface reaction, increases the lithium ion transport rate, further improves the rate performance of the negative electrode active material, and allows the expansion force generated during the lithium deintercalation process of the negative electrode active material to be released along multiple directions. Furthermore, it reduces the change in thickness of the negative electrode plate during the charging process, thereby reducing battery expansion.

[0034] Specifically, secondary graphite particles can be obtained by bonding primary graphite particles together. However, when primary graphite particles are bonded together with an adhesive, many irregularities are formed on the surface of the secondary graphite particles. These irregularities have a relatively high adsorption capacity for the dispersant, and a large amount of the dispersant in the negative electrode slurry is adsorbed onto the surface of the secondary particles. This blocks the lithium storage and desorption channels on the graphite surface, resulting in relatively little free dispersant in the negative electrode slurry and relatively poor stability of the negative electrode slurry. In this case, the negative electrode active material exhibits a relatively high oil absorption value. Furthermore, it is necessary to filter the negative electrode slurry before coating to remove impurities. However, the irregularities on the surface of the secondary particles make it difficult for the graphite to disperse completely in the negative electrode slurry, reducing the stability of the negative electrode slurry, and the negative electrode slurry cannot meet the filtration requirements.

[0035] To compensate for the excessive adsorption of the relatively large oil absorption value of the negative electrode active material onto the dispersant and to achieve uniform dispersion of the negative electrode slurry, it is necessary to add more dispersant to the negative electrode slurry. However, since the dispersant itself does not have the function of lithium intercalation and deintercalation, this leads to a decrease in the proportion of negative electrode active material that can provide lithium intercalation and deintercalation sites in the negative electrode slurry. Consequently, the proportion of negative electrode active material in the negative electrode active material layer formed by coating the negative electrode slurry decreases, ultimately leading to a decrease in the specific capacity of the negative electrode plate.

[0036] In this application, when the proportion of secondary particles in the negative electrode active material is 65% or more, the proportion of secondary particles in the negative electrode active material is relatively high, which can effectively improve the rate performance of the negative electrode active material and reduce the volume expansion rate of the negative electrode active material during the charge-discharge process. Furthermore, in the process of bonding graphite primary particles to form graphite secondary particles, small particle size fine powders tend to form protruding structures on the surface of the secondary particles, resulting in an excessively high oil absorption value of the negative electrode active material. When the Dv1 particle size of the negative electrode active material is 4μm-8μm, there are very few fine particles with a particle size of less than 3μm in the negative electrode active material, which can control the oil absorption value of the negative electrode active material within an appropriate range. This contributes to the fact that, in this case, the oil absorption value of the negative electrode active material may be 40 mL / 100 g to 65 mL / 100 g, the number and proportion of uneven structures on the surface of the negative electrode active material are appropriate, and when the amount of adhesive used in the negative electrode slurry is relatively small, the negative electrode active material still has relatively good dispersibility in the negative electrode slurry, the processing performance of the negative electrode slurry is relatively good, and only a relatively small amount of dispersant needs to be used in the negative electrode slurry, eliminating the need to further increase the content of dispersant in the negative electrode slurry, thereby reducing the manufacturing cost of the negative electrode slurry, improving the proportion of negative electrode active material in the negative electrode slurry, and improving the dynamic performance of the negative electrode plate.

[0037] For example, the negative electrode active material can be manufactured by the following method: the raw material is subjected to a grinding treatment and a second classification treatment to obtain primary graphite particles; the primary graphite particles are mixed with an adhesive and subjected to a first heat treatment to obtain pre-bonded secondary particles; the pre-bonded secondary particles are subjected to a second heat treatment and a first classification treatment to obtain secondary particles; and the secondary particles are mixed with a liquid phase coating agent and subjected to a third heat treatment to form a carbon coating layer on a portion of the surface of the secondary particles to obtain the negative electrode active material.

[0038] In some embodiments, the consistency of particle size and the roundness of the surface of the negative electrode active material can be controlled by grinding, shaping, and classification of the raw material. For example, if the host frequency of the grinding process is appropriate, the particle size after grinding is appropriate; if the host frequency of the shaping process is appropriate, the surface morphology of the particles is rounder and the particle size is appropriate; and if the frequency of the classification process is appropriate, the consistency of particle size is relatively high. Specifically, after crushing centimeter-level raw coke raw material to micron-level raw material by grinding, the crushed small-particle raw material is classified and sieved by a second classification process to remove fine particles that are too small in size from the raw material, and reduce the formation of protruding structures due to the relatively small size of the fine particle impurities. Furthermore, a shaping process can be performed between the grinding process and the second classification process, thereby reducing the aspect ratio of the graphite particles, increasing their sphericity, improving the particle shape, particle size distribution, and surface properties of the primary particle powder, and improving the uniformity of the particle size of the graphite primary particles.

[0039] In some embodiments, the first classification process can effectively sieve and remove fine particles from the secondary particle powder, effectively reducing the formation of protruding surfaces in the subsequent surface coating process, and further reducing the oil absorption value of the negative electrode active material.

[0040] In some embodiments, the liquid phase coating agent has the advantages of excellent fluidity, spreading more uniformly on the surface of secondary particles, resulting in fewer surface protrusions, and better coating of the secondary particle surface. This reduces the formation of protruding surfaces during the coating process and further contributes to reducing the oil absorption value of the negative electrode active material.

[0041] In this application, "oil absorption value of negative electrode active material" has the meaning known in the art and can be measured using instruments and methods known in the art. For example, the oil absorption value can be obtained based on the amount of dibutyl phthalate used when a mixture of negative electrode active material and dibutyl phthalate changes from a free-flowing state to a semi-plastic aggregate. Specifically, 100 g of negative electrode active material is placed in the supply port of an oil absorption value tester, and dibutyl phthalate is automatically titrated by the instrument and flowed over the negative electrode active material until the negative electrode active material becomes a semi-plastic aggregate. The amount of dibutyl phthalate added at this time (a mL) is recorded, thereby obtaining that the oil absorption value of this negative electrode active material is a mL / 100 g.

[0042] In this application, "the proportion of secondary particles in the negative electrode active material" has a meaning known in the art and can be measured using instruments and methods known in the art. For example, it can be measured using a scanning electron microscope. As an example, a method for testing the proportion of secondary particles may be as follows: The negative electrode active material is laid and bonded to a conductive adhesive to produce a test sample of length × width = 6 cm × 1.1 cm, and the particle morphology is tested using a scanning electron microscope (e.g., ZEISS Sigma 300). The test can be described by referring to JY / T010-1996. To ensure the accuracy of the test results, multiple (e.g., 20) different areas are randomly selected from the test sample and scanned, and the percentage of secondary particles in each test area relative to the total number of particles is calculated at a constant magnification rate (e.g., 1000x), which is the proportion of secondary particles in that area. The average value of the test results from multiple test areas is then taken as the proportion of secondary particles in the negative electrode active material.

[0043] In some embodiments, the negative electrode active material layer on the surface of the negative electrode plate is removed by doctor blade processing, and then fired in a muffle furnace to remove substances such as adhesives, conductive agents, and dispersants from the negative electrode active material, thereby obtaining negative electrode active material powder. Furthermore, the ratio of secondary particles can be calculated as follows: (a) a vacuum negative pressure sputtering method is adopted to uniformly disperse the aforementioned negative electrode active material powder onto a conductive tape substrate; (b) the mapping function of a scanning electron microscope (e.g., Thermo Scientific Apreo 2 S) is used to achieve high-speed capture of 50 images; (c) AI technology is used to automatically mark particles in each image to obtain the number of primary and secondary particles, and the results are statistically analyzed to calculate the ratio of secondary particles. Here, a secondary particle is defined as a single particle when two or more particles are stacked. For example, secondary particles may be stacked from multiple particles of different particle sizes (see Figure 9 (1)), stacked from multiple particles of similar particle sizes (see Figure 9 (2)), or stacked from multiple small particles on the surface of one large particle (see Figure 9 (3)).

[0044] According to a first aspect of this application, the application provides a battery comprising a positive electrode plate, a negative electrode plate, and a separator, wherein the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer located at least on one side of the negative electrode current collector, the negative electrode active material layer includes a negative electrode active material, the negative electrode active material includes graphite, the proportion of secondary particles in the negative electrode active material is 65% or more, the oil absorption value of the negative electrode active material is 40 mL / 100 g to 65 mL / 100 g, and the volume distribution particle size Dv1 of the negative electrode active material is 4 μm to 8 μm. This significantly improves the rate performance and processing performance of the negative electrode active material, contributing to an improvement in the rate performance of the battery.

[0045] When the proportion of secondary particles in the negative electrode active material is 65% or more, the number of lithium ion intercalation and deintercalation channels in the negative electrode active material can be significantly improved, further enhancing the rate performance of the negative electrode active material. Furthermore, when the oil absorption value of the negative electrode active material is 40 mL / 100 g to 65 mL / 100 g, the surface irregularities of the negative electrode active material are relatively few, uniform dispersion of the negative electrode active material can be achieved with relatively little dispersant, and the processing performance of the negative electrode active material is relatively excellent.

[0046] For example, the ratio of secondary particles in the negative electrode active material may be 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%.

[0047] As can be understood, the higher the proportion of secondary particles in the negative electrode active material, the better the kinetic performance of the negative electrode active material. When all particles in the negative electrode active material are secondary particles, the kinetic performance of the negative electrode active material is optimal. In this case, the proportion of adhesive that binds adjacent primary particles in the negative electrode active material is relatively high, and the adhesive itself can only serve as lithium ion intercalation and deintercalation channels, and cannot serve as intercalation and deintercalation sites. Therefore, the negative electrode active material has relatively high kinetic performance and relatively low gram capacity. A person skilled in the art can adjust the proportion of secondary particles in the negative electrode active material according to the actual situation.

[0048] The proportion of secondary particles in the negative electrode active material is influenced by the adhesive content and particle size of the negative electrode active material. Specifically, when the adhesive content in the negative electrode active material is relatively high, the proportion of secondary particles in the negative electrode active material is relatively high as the adhesion between graphite primary particles is sufficient. Furthermore, when the particle size of the adhesive is relatively small, the adhesive can provide a relatively large viscous surface, which leads to relatively greater effective adhesion between primary particles, resulting in a relatively high proportion of secondary particles in the negative electrode active material.

[0049] In some embodiments, the mass ratio of the adhesive to the graphite primary particles is (7-10):100. In some other embodiments, the particle size of the adhesive is 4 μm-8 μm.

[0050] For example, the oil absorption values ​​of the negative electrode active material are 40 mL / 100g, 41 mL / 100g, 42 mL / 100g, 43 mL / 100g, 44 mL / 100g, 45 mL / 100g, 46 mL / 100g, 47 mL / 100g, 48 mL / 100g, 49 mL / 100g, 50 mL / 100g, 51 mL / 100g, and 52 mL / 100g. It may also be 00g, 53mL / 100g, 54mL / 100g, 55mL / 100g, 56mL / 100g, 57mL / 100g, 58mL / 100g, 59mL / 100g, 60mL / 100g, 61mL / 100g, 62mL / 100g, 63mL / 100g, 64mL / 100g, or 65mL / 100g.

[0051] When the oil absorption value of the negative electrode active material is between 40 mL / 100 g and 65 mL / 100 g, the negative electrode active material possesses both relatively good kinetic performance and relatively good gram capacity.

[0052] In some embodiments, the negative electrode active material contains graphite, the proportion of secondary particles in the graphite is 65% or more, and the oil absorption value of the graphite is 40 mL / 100 g to 65 mL / 100 g.

[0053] In some embodiments, the volume distribution particle size Dv1 of the negative electrode active material is 4 μm to 8 μm.

[0054] In the process of primary particles adhering to form secondary particles, small-particle fine powders tend to form protruding structures on the surface of the secondary particles, resulting in excessively high oil absorption of the negative electrode active material. When the Dv1 particle size of the negative electrode active material is 4 μm-8 μm, there are very few fine particles with a particle size of less than 3 μm in the negative electrode active material. This is advantageous for controlling the oil absorption value of the negative electrode active material within an appropriate range, and further improves the processing performance of the negative electrode active material.

[0055] The aforementioned Dv1 particle size is the particle size corresponding to the point when the cumulative volume distribution percentage of the particle reaches 1%.

[0056] In some embodiments, the negative electrode active material satisfies the condition that (Dv90-Dv10) / Dv50 is between 0.8 and 1.2. This improves the kinetic performance of the negative electrode active material.

[0057] For example, (Dv90-Dv10) / Dv50 could be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, or 1.2.

[0058] When the negative electrode active material satisfies the condition that (Dv90-Dv10) / Dv50 is between 0.8 and 1.2, on the one hand, the particle size distribution of the negative electrode active material is relatively good, the curvature of the lithium ion intercalation / deintercalation channel is relatively low, the transmission path is relatively short, and the negative electrode active material has relatively good dynamic performance. On the other hand, the tap density of the negative electrode active material is also affected by the particle size distribution range. When the particle size distribution of the negative electrode active material is within the above range, there are relatively few small particles in the negative electrode active material, aggregation between small particles is relatively low, and the number of large particles formed by the aggregation of small particles is effectively reduced, resulting in the negative electrode active material containing an appropriate number of large and small particle sizes, and the tap density is significantly improved.

[0059] The aforementioned Dv10 particle size is the particle size corresponding to the point when the cumulative volume distribution percentage of the particle reaches 10%.

[0060] The aforementioned Dv50 particle size refers to the particle size at which the cumulative volume distribution percentage of the particle reaches 50%.

[0061] The aforementioned Dv90 particle size refers to the particle size at which the cumulative volume distribution percentage of the particle reaches 90%.

[0062] In some embodiments, the volume distribution particle size Dv10 of the negative electrode active material is 7 μm-11 μm, and / or the volume distribution particle size Dv90 of the negative electrode active material is 20 μm-30 μm, and / or the volume distribution particle size Dv50 of the negative electrode active material is 12 μm-18 μm. This can further improve the rate performance of the negative electrode active material.

[0063] For example, the volume distribution particle size Dv10 of the negative electrode active material may be 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, or 11 μm.

[0064] For example, the volume distribution particle size Dv50 of the negative electrode active material may be 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, or 18 μm.

[0065] For example, the volume distribution particle size Dv90 of the negative electrode active material may be 20 μm, 20.5 μm, 21 μm, 21.5 μm, 22 μm, 22.5 μm, 23 μm, 23.5 μm, 24 μm, 24.5 μm, 25 μm, 25.5 μm, 26 μm, 26.5 μm, 27 μm, 27.5 μm, 28 μm, 28.5 μm, 29 μm, 29.5 μm, or 30 μm.

[0066] In this application, "particle size" has the meaning known in the art and can be measured using instruments and methods known in the art. For example, the particle size of the negative electrode active material can be measured by laser diffraction particle size analysis. Specifically, it can be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000), referring to standard GB / T 19077-2016.

[0067] In some embodiments, the negative electrode active material may contain graphite, and the powder OI value of the negative electrode active material may be 2-7. This can improve the lithium ion intercalation and deintercalation rate of the negative electrode active material.

[0068] After manufacturing the negative electrode plate from graphite, the orientation of the graphite layer structure significantly affects lithium ion movement. Since only the end faces of the graphite can intercept and deintercept lithium ions, in ideal conditions, it is advantageous for lithium ion diffusion when the end faces of the graphite material in the negative electrode active material are perpendicular to the surface of the negative electrode plate. However, it is difficult to accurately control the orientation of each graphite particle during actual manufacturing. XRD can be used to test the orientation of graphite on the negative electrode plate. When performing a diffraction pattern test on a horizontally placed negative electrode plate sample, the diffraction signal of the collectible (110) crystal plane originates from graphite perpendicular to the surface of the negative electrode plate in the negative electrode active material layer, while the diffraction signals of the (002) and (004) crystal planes originate from graphite whose structure in the negative electrode active material is parallel to the surface of the electrode plate. Therefore, the orientation of the graphite electrode can be described by the ratio of the (002) or (004) diffraction peak intensity (or integrated area) to the (110) diffraction peak intensity (or integrated area). The formula is written as OI = I(002) / I(110) or OI = I(004) / I(110), where OI (orientation index) is the orientation of graphite in the negative electrode active material layer.

[0069] When the powder OI value of the negative electrode active material is 2-7, it is advantageous to improve the volume expansion and reaction kinetics of graphite, enhance the isotropy of graphite, effectively mitigate the volume expansion effect during the negative electrode plate cycle process, and further improve the battery's cycle performance.

[0070] For example, the OI value may be 2, 3, 4, 5, 6, or 7.

[0071] In some embodiments, the degree of graphitization of the negative electrode active material is 93%-95%. This improves the electronic conductivity of the negative electrode active material.

[0072] The degree of graphitization refers to the extent to which carbon atoms form a hexagonal close-packed hexagonal graphite crystal structure. The closer the lattice size is to the lattice parameters of ideal graphite, the higher the degree of graphitization.

[0073] The "graphitization degree" of the negative electrode active material has the meaning known in the art and may be tested using methods known in this field. For example, it can be tested using an X-ray diffractometer (e.g., Bruker D8 Discover). The test can refer to JIS K 0131-1996 and JB / T 4220-2011, measure the size of d 002 , and then calculate the graphitization degree based on the formula G=(0.344 - d 002 ) / (0.344 - 0.3354)×100%, where d 002 is the interlayer spacing in the graphite crystal structure calculated in nm. In the X-ray diffraction analysis test, Cu Kα radiation is used as the radiation source, the 2θ angle range of the radiation wavelength scanning is 20° - 80°, and the scanning speed is 4° / min.

[0074] When the graphitization degree of the negative electrode active material is within the above-mentioned range, the structure of the negative electrode active material is regular, defects such as stacking defects and dislocations in the crystal are relatively few, the electron transfer resistance is relatively small, and the kinetic performance of the negative electrode active material is improved.

[0075] As an example, the graphitization degree of the negative electrode active material may be 93%, 93.5%, 94%, 94.5% or 95%.

[0076] In some embodiments, the specific surface area of the negative electrode active material is 2.5 m 2 / g - 3.5 m 2 / g. Thereby, the processing performance of the negative electrode active material can be further improved.

[0077] Specific surface area refers to the surface area of ​​an object per unit mass. The smaller the particle size of the negative electrode active material, the larger the specific surface area. Consequently, there are more channels for lithium ion movement, shorter pathways, and the rate performance of the negative electrode active material is relatively high. At the same time, more dispersant is needed for dispersion. In other words, the larger the specific surface area of ​​the negative electrode active material, the greater its oil absorption value. When the specific surface area of ​​the negative electrode active material is within the aforementioned range, the negative electrode active material has relatively good rate performance and relatively low oil absorption, eliminating the need to add extra dispersant when manufacturing the negative electrode slurry.

[0078] To make it clear, the specific surface area is affected by the material particle size distribution, and if the particle size of the negative electrode active material satisfies the aforementioned limitations, a specific surface area within the above range can be obtained.

[0079] The "specific surface area" of the negative electrode active material has a meaning known in this field and may be tested using methods known in this field. For example, using a Micromeritics GeminiVII2390 multi-station fully automated specific surface area and pore size analyzer from the United States, a sample of approximately 7 g of negative electrode active material can be taken, placed in a 9 cc long tube with bubbles, degassed at 150°C for 15 mins, and then placed in a host test to obtain BET data.

[0080] In some embodiments, the negative electrode active material further includes a carbon coating layer, the carbon coating layer located on at least a portion of the surface of the secondary particles, the secondary particles being formed by bonding at least two primary particles, and the bonding material including a carbon material. This can improve the conductivity of the negative electrode active material.

[0081] By installing a carbon coating layer, the active sites on the surface of the graphite secondary particles are covered, reducing the occurrence of irreversible side reactions, decreasing the specific surface area of ​​the negative electrode active material, isolating the graphite secondary particles from the electrolyte, and reducing direct contact between the secondary particles and the electrolyte in the negative electrode active material. Furthermore, it provides constraint and buffering effects against the volume expansion of graphite, thereby improving cycle stability.

[0082] For example, the carbon coating layer may contain amorphous carbon. The amorphous carbon coating layer has a relatively large interlayer spacing, which is advantageous in improving the diffusion rate of lithium ions within the negative electrode active material, enhancing high-current charge / discharge capability, and improving the battery's performance at high rates.

[0083] In some embodiments, the tap density of the negative electrode active material is 0.9 g / cm³. 3 -1.15 g / cm³ 3 This allows for improved processing performance of the negative electrode active material.

[0084] Tap density refers to the mass per unit volume measured after tapping the powder in a container under predetermined conditions, and its unit is g / cm³. 3 It is measured using special tap density equipment.

[0085] When the tap density of the negative electrode active material is within the aforementioned range, the amount of voids in the negative electrode active material is appropriate and favorable for electrolyte infiltration, making it easier for lithium ions to be absorbed into the negative electrode active material and improving rate performance.

[0086] Tap density can reflect the oil absorption value of the negative electrode active material to some extent. When the surface of the negative electrode active material has relatively few irregularities, the negative electrode active material can adhere more tightly. In this case, the tap density of the negative electrode active material is relatively high, and the oil absorption value of the negative electrode active material is also relatively low because the surface has relatively few irregularities.

[0087] To make it clear, tap density is affected by the material particle size, and if the particle size of the negative electrode active material satisfies the aforementioned limitations, a tap density within the above range can be obtained.

[0088] In some embodiments, the compaction density of the negative electrode active material at a pressure of 50,000 N is 1.75 g / cm³. 3 -1.85 g / cm³ 3 This allows us to increase the energy density of the negative electrode active material layer containing this negative electrode active material.

[0089] Secondary particles are formed by the adhesion of primary particles, and since the adhesive does not have lithium intercalation / deintercalation sites, the gram capacity of secondary particles is slightly lower than that of primary particles, and the compaction density of secondary particles is higher than that of primary particles. Generally, the higher the compaction density of the negative electrode active material, the higher the energy density of the battery. When the compaction density of the negative electrode active material that satisfies the aforementioned proportion of secondary particles is within the aforementioned range under a pressure of 50,000 N, the thickness of the negative electrode plate after rolling is relatively small, the volumetric energy density of the battery is relatively high, and voids in the negative electrode plate are retained, which is advantageous for lithium ion intercalation and deintercalation.

[0090] In some embodiments, the gram capacity of the negative electrode active material is 355 mAh / g to 360.5 mAh / g. This results in the negative electrode active material having a relatively high gram capacity.

[0091] Secondary particles are formed by the adhesion of primary particles, and since the adhesive does not have lithium absorption / desorption sites and cannot contribute to the gram capacity, the gram capacity of secondary particles is slightly lower than that of primary particles. When the gram capacity of the negative electrode active material is 355 mAh / g to 360.5 mAh / g, the proportion of adhesive used to adhere the primary particles in the negative electrode active material is relatively small, and the negative electrode active material still has a relatively high gram capacity.

[0092] In some embodiments, when the surface of the negative electrode active material has a carbon coating layer, the Id / Ig peak intensity ratio of the Raman spectrum of the negative electrode active material is 0.20-0.40.

[0093] Raman scattering analysis of the negative electrode active material showed a Raman shift of 1320 cm⁻¹. -1 -1410cm -1 and 1550cm -1 -1650cm -1 Each has a scattering peak at the position indicated by the following: In other words, in the Raman spectrum of the negative electrode active material, the Raman shift is 1320 cm⁻¹. -1 -1410cm -1 It has a carbon D-band scattering peak (abbreviated as the D peak) at this position, and the Raman shift is 1550 cm⁻¹.-1 -1650cm -1 The Raman spectrum of the negative electrode active material has a carbon G-band scattering peak (abbreviated as the G-peak) at this position. The ratio of the peak intensity Id of the D-peak to the peak intensity Ig of the G-peak can reflect the degree of defects in the negative electrode active material. When the Id / Ig peak intensity ratio of the negative electrode active material's Raman spectrum is within the aforementioned range, it indicates that there are relatively many surface defect sites in the negative electrode active material, which is advantageous for improving the battery's performance at high rates.

[0094] In some embodiments, the porosity of the negative electrode active material layer is 18%-35%. This is advantageous for the penetration of the electrolyte into the negative electrode plate.

[0095] For example, the porosity of the negative electrode active material layer may be 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%.

[0096] When the porosity of the negative electrode active material layer is within the aforementioned range, the negative electrode active material layer has a relatively large number of voids, which is advantageous for the penetration of the electrolyte into the negative electrode plate, resulting in good ion transport characteristics and a relatively high energy density of the negative electrode slurry.

[0097] In some embodiments, the compaction density of the negative electrode active material layer is 1.60 g / cm³. 3 -1.75 g / cm³ 3 This is advantageous for the electrolyte to penetrate the negative electrode plate.

[0098] For example, the compaction density of the negative electrode active material layer is 1.60 g / cm³. 3 , 1.61 g / cm³ 3 , 1.62 g / cm³ 3 1.63 g / cm³ 3 1.64 g / cm³ 3 1.65 g / cm³ 3 1.66 g / cm³ 3 1.67 g / cm³ 3 1.68 g / cm³ 3 1.69 g / cm³ 31.70 g / cm³ 3 1.71 g / cm³ 3 1.72 g / cm³ 3 1.73 g / cm³ 3 1.74 g / cm³ 3 Or 1.75 g / cm³ 3 That's fine.

[0099] The compaction density of the negative electrode active material layer is related to the porosity of the negative electrode active material layer. If the compaction density of the negative electrode active material layer is within the range described above, the porosity of the negative electrode active material layer can satisfy the requirements described above.

[0100] In some embodiments, the surface density of the negative electrode active material layer is 5 mg / cm². 2 -10 mg / cm³ 2 That is the case.

[0101] For example, the negative electrode current collector has two opposing surfaces in the thickness direction of itself, and the negative electrode active material layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0102] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0103] In some embodiments, the negative electrode active material layer may employ a negative electrode active material used in batteries known in the art, in addition to the negative electrode active material described above.

[0104] For example, the negative electrode active material may further include at least one material from among artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material includes at least one from among elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material includes at least one from among elemental tin, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may be used. These negative electrode active materials may be used individually or in combination of two or more.

[0105] In some embodiments, the negative electrode active material layer further selectively includes an adhesive. The adhesive includes at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0106] In some embodiments, the negative electrode active material layer further selectively includes a conductive agent. The conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the negative electrode active material layer further selectively comprises a dispersant, such as sodium carboxymethylcellulose (CMC-Na), polyacrylic acid, etc.

[0108] According to a second aspect of this application, this application provides a method for manufacturing the aforementioned battery, thereby enabling the production of a battery having the aforementioned relatively excellent rate performance in a simple manner. Specifically, the method for manufacturing the negative electrode active material includes the following:

[0109] S100: Graphite primary particles are mixed with an adhesive and subjected to a first heat treatment.

[0110] In some embodiments, primary graphite particles are mixed with an adhesive in this step, and pre-bonded secondary particles are obtained by a first heat treatment.

[0111] For example, primary graphite particles can be mixed with an adhesive, then stirred and heated in a high-temperature reaction vessel, and cooled to obtain pre-bonded secondary particles. Furthermore, the pre-bonded secondary particles can be subjected to a shaping process, which disperses pre-bonded secondary particles whose adhesion is not sufficiently strong, thereby reducing cracking and crushing of the secondary particles in the subsequent roll press process.

[0112] In some embodiments, the method for obtaining primary graphite particles is not particularly limited. For example, providing the primary graphite particles may involve crushing and a second classification process on a raw material containing at least one of petroleum coke and needle coke to obtain the primary graphite particles.

[0113] The first pulverization process can crush centimeter-level raw materials into micron-level raw materials, and the second classification process can classify and sieve the small-particle raw materials to remove fine powders that are too small in size. Furthermore, a shaping process can be performed between the pulverization and the second classification process, which significantly reduces the aspect ratio of the graphite particles and increases their sphericity. This improves the mechanical properties and volume utilization rate of the graphite, improves the particle shape, particle size distribution, and surface properties of the primary particle powder, and improves the uniformity of the particle size of the graphite primary particles.

[0114] For example, the second classification process may specifically include a classification step and a sieving step.

[0115] For example, the crushing, shaping, and second classification processes of the raw materials may be carried out in a continuous processing machine.

[0116] When the shaping frequency is appropriate, the shaping process can make the surface morphology of the primary graphite particles rounder and the primary graphite particles themselves more appropriate.

[0117] In some embodiments, the supply frequency for the grinding process is 10Hz-35Hz, and the classification frequency for the second classification process is 30Hz-50Hz.

[0118] When the grinding and second classification processes of the raw material are carried out using a continuous apparatus, the fine powder content in the primary graphite particles can be effectively controlled by controlling the supply frequency of the grinding process and the classification frequency of the second classification process. When the supply frequency of the grinding process and the classification frequency of the second classification process are within the aforementioned range, the supply frequency is appropriate, the raw material particles can be sufficiently crushed, and the generated fine powder can be effectively removed in the subsequent second classification process. At the same time, the overall particle size of the primary graphite particles does not become too large, which affects the dynamic performance of the negative electrode active material.

[0119] In some embodiments, the true density of the raw material is 1.35 g / cm³. 3 -1.50 g / cm³ 3 That is the case.

[0120] The true density of the raw material is 1.35 g / cm³. 3 -1.50 g / cm³ 3 In this case, the bulk phase of the raw material is relatively dense, with relatively few voids, and the gram capacity of the graphite secondary particles obtained after the second heat treatment process is higher.

[0121] In some embodiments, the volatile content in the raw material is 4%-7%. The sulfur content of the raw material is 2% or less.

[0122] When the volatile matter and sulfur content of the raw materials are within the aforementioned ranges, the volatile matter content in the raw materials is appropriate, the sulfur content is relatively low, the impurity components in the raw materials are relatively few, the crystal development is anisotropically biased, and the gram capacity is relatively good.

[0123] In some embodiments, the adhesive may be a solid adhesive, for example, the adhesive comprising at least one of asphalt and resin, the solid adhesive contributing to blending with the primary particles, readily adhering to the primary particles, having relatively strong adhesion, thereby improving the adhesive effect of the adhesive on the graphite primary particles.

[0124] In some embodiments, the caulking value of the adhesive is 60%-70%.

[0125] Primary particles are mainly bonded together by adhesive to form secondary particles. If the caulking value of the adhesive is within the aforementioned range, then the amount of carbon material remaining in the adhesive during the first heat treatment process is appropriate, the structure of the secondary particles is relatively dense, the oil absorption value is appropriate, and the proportion of secondary particles can be increased by adding only a small amount of adhesive.

[0126] In some embodiments, the mass ratio of the adhesive to the graphite primary particles is (7-10):100.

[0127] When the mass ratio of adhesive to primary graphite particles is within the aforementioned range, the adhesion between primary graphite particles is sufficient, the proportion of secondary particles in the negative electrode active material is relatively high, the structure of the pre-adhered secondary particles is relatively dense, and the compaction density of the final negative electrode active material is relatively high.

[0128] In some embodiments, the particle size of the adhesive is 4 μm to 8 μm.

[0129] When the particle size of the adhesive is within the aforementioned range, the particle size of the adhesive is appropriate, the viscous surface that the adhesive can provide is relatively large, thereby allowing for relatively large amounts of effective adhesion between primary particles, the proportion of secondary particles in the negative electrode active material is relatively high, and the adhesive itself does not aggregate and disperse, and furthermore does not perform an adhesive action, its own steric hindrance is relatively small, and it can effectively come into contact with the graphite primary particles and form adhesion.

[0130] In some embodiments, the temperature of the first heat treatment is 600°C-800°C, and the duration of the first heat treatment is 1h-4h. This contributes to improving the pre-adhesion of the adhesive to the primary graphite particles.

[0131] The first heat treatment allows primary particles to be bonded with an adhesive. At the bonding site, the adhesive undergoes a thermal decomposition reaction at the temperature of the first heat treatment, forming carbon. This relieves the volume contraction stress caused by the thermal decomposition of the primary particles during the subsequent second heat treatment, and further reduces the collapse of the graphite secondary particle structure due to volume contraction stress.

[0132] When the time and temperature of the first heat treatment meet the aforementioned ranges, the amount of residual carbon volatiles formed at the bonding site of the adhesive is relatively small, the adhesion between primary particles is relatively stable, the time required for the first heat treatment is relatively short, and energy consumption is relatively low.

[0133] S200: The pre-bonded secondary particles are subjected to a second heat treatment and a first classification treatment.

[0134] In some embodiments, secondary particles are obtained by performing a second heat treatment and a first classification treatment on pre-bonded secondary particles.

[0135] For example, pre-bonded secondary particles can be subjected to a second heat treatment in an Acheson graphitization furnace, cooled, and then subjected to a first classification treatment, followed by classification and sieving to control the fine powder content, thereby obtaining graphitized secondary particles.

[0136] In some embodiments, the temperature of the second heat treatment is 2800°C-3300°C, and the duration of the second heat treatment is 36h-72h. This contributes to improving the adhesion effect of the adhesive to the graphite primary particles.

[0137] When the time and temperature of the second heat treatment are within the aforementioned range, the heat treatment time is appropriate, energy consumption is relatively low, and heat capacity is relatively high, contributing to the sufficient graphitization of the adhesive.

[0138] In related technologies, graphite secondary particles and a solid-phase coating agent are mixed, carbonized, and then sieved to obtain a negative electrode active material having a surface carbon coating layer. However, solid-phase mixing can only uniformly disperse the secondary particles and coating agent after mixing. However, the materials need to be transported to the carbonization line by mixing equipment, and during the transport and movement process, differences in density and particle size exist between the coating agent and the graphite secondary particles, resulting in uneven dispersion. After carbonization, the surface morphology of the particles becomes irregular, generating a large amount of uneven structure, and the oil absorption value of the manufactured negative electrode active material is too high. Furthermore, since the carbonization process after mixing the graphite secondary particles with the coating agent is static, the fine impurities doped into the secondary particles, being relatively small in size, tend to self-aggregate, forming protruding structures on the surface of the secondary particles. Subsequently, in the coating process, the aggregated fine particles adhere to the surface of the secondary particles by the coating agent, further forming protrusions. This results in relatively poor surface morphology of the secondary particles, increasing the oil absorption value of the negative electrode active material and requiring dispersion with more dispersant.

[0139] In some embodiments, the first classification process can sieve and remove fine particles from the secondary particle powder, effectively reducing the formation of protruding surfaces in the subsequent surface coating process.

[0140] In some embodiments, when the first classification process is performed in a continuous apparatus, the fine powder content in the graphite secondary particles can be effectively controlled by controlling the supply frequency and classification frequency of the first classification process.

[0141] In some embodiments, the supply frequency of the first classification process is 4Hz-10Hz, which allows for a moderate supply frequency, effective removal of fine particles, and improved processing performance of the negative electrode active material.

[0142] For example, the supply frequency for the first classification process may be 4Hz, 5Hz, 6Hz, 7Hz, 8Hz, 9Hz, or 10Hz.

[0143] In some embodiments, the classification frequency of the first classification process is 30Hz-50Hz, which allows for the effective removal of fine particles and improves the processing performance of the anode active material, while preventing the overall particle size of the graphite secondary particles from becoming too large and affecting the dynamic performance of the anode active material.

[0144] For example, the supply frequency for the first classification process may be 30Hz, 35Hz, 40Hz, 45Hz, or 50Hz.

[0145] When the supply frequency and classification frequency of the first classification process are within the aforementioned range, the first classification process sieves and removes fine particles from the powder, resulting in an appropriate overall particle size of secondary particles in the negative electrode active material and relatively good dynamic performance. As a result, the fine particle content in the negative electrode active material decreases, the Dv1 particle size of the negative electrode active material increases slightly, the Dv50 particle size of the negative electrode active material is appropriate, the adhesion between primary particles in the negative electrode active material becomes more uniform, the number of secondary particles in the negative electrode active material is relatively large, and the dynamic performance of the negative electrode active material is relatively good.

[0146] In some embodiments, the first classification process may specifically include a classification step and a sieving step, and the number of screen meshes in the sieving step may be 300-350 meshes.

[0147] When the screen mesh count falls within the aforementioned range, the particle size of the secondary particles obtained after sieving is appropriate, and not only does it have a relatively high gram capacity, but it can also reduce the occurrence of coating scratches during the processing.

[0148] In some embodiments, the method for producing the negative electrode active material is as follows: S300: This includes mixing the secondary particles with a liquid phase coating agent and performing a third heat treatment.

[0149] In some embodiments, secondary particles and a liquid phase coating agent are placed in a mechanical fusion machine and stirred, then subjected to high-temperature carbonization and cooled to room temperature, after which a negative electrode active material of the required particle size can be obtained by sieving.

[0150] By installing a carbon coating layer, the active sites on the surface of the graphite secondary particles are covered, reducing the occurrence of irreversible side reactions, decreasing the specific surface area of ​​the negative electrode active material, isolating the graphite secondary particles from the electrolyte, and reducing direct contact between the secondary particles and the electrolyte in the negative electrode active material. Furthermore, it provides constraint and buffering effects against the volume expansion of graphite, thereby improving cycle stability.

[0151] Compared to solid-phase coatings, liquid-phase coatings have the advantage of superior fluidity, spreading more uniformly across the surface of secondary particles, resulting in fewer surface protrusions and better coating of the secondary particle surface. Furthermore, since mixing secondary particles with the liquid-phase coating and performing a third heat treatment generally require different equipment, and during material transport and movement processes, the liquid-phase coating can more stably coat the surface of graphite secondary particles, resulting in relatively high dispersion uniformity.

[0152] In some embodiments, the liquid phase coating agent includes at least one of asphalt and resin having a viscosity of 500 mPa·s or less. This results in a relatively high coating effect of the liquid phase coating agent on secondary particles.

[0153] The lower the viscosity of the liquid phase coating agent, the better its fluidity, the more sufficient the contact between the graphite secondary particles and the liquid phase coating agent, the fewer surface protrusions formed after coating, and the relatively better the processing performance of the negative electrode active material.

[0154] To make it easier to understand, the viscosity of a liquid phase coating is related to its molecular weight. Specifically, if the viscosity of the liquid phase coating is too low, its molecular weight is too small, and in this case, the caulking value of the liquid phase coating is too low.

[0155] In some embodiments, the mass ratio of the liquid phase coating agent to the secondary particles is (2-10):100.

[0156] The main function of the surface coating is to cover the active sites on the surface of secondary particles, reduce the occurrence of irreversible side reactions, and allow the secondary particles in the modified negative electrode active material to retain the advantages of graphite-based materials, namely high capacity and low potential. The carbon coating layer located on the graphite surface has good electrolyte compatibility and effectively suppresses adverse effects such as graphite peeling, pulverization, and volume expansion due to solvation. However, there are limits to the improvement of the gram capacity of the negative electrode active material by the surface carbon coating layer, and an excessively thick surface carbon coating layer significantly reduces the gram capacity of the negative electrode active material. When the mass ratio of the liquid phase coating agent to the secondary particles is (2-10):100, the negative electrode active material has relatively good electrolyte resistance and a high gram capacity.

[0157] In some embodiments, the caulking value of the liquid phase coating agent is 40%-70%.

[0158] If the coking value of the liquid phase coating is within the range described above, and the amount of carbon formation does not change after the liquid phase coating is heat-treated, the addition ratio of the liquid phase coating is relatively appropriate, there are a relatively large number of contact points with the secondary particles, the surface coating of the secondary particles is relatively complete, and the amount of volatile matter that the liquid phase coating needs to discharge during the carbonization process is relatively small, significantly reducing the possibility of the exhaust port of the carbonization furnace reacting with air and causing a risk.

[0159] In some embodiments, the temperature of the third heat treatment is 1000°C-1200°C, and the duration of the third heat treatment is 15h-30h. This contributes to the formation of an amorphous carbon coating layer.

[0160] When the temperature and time of the third heat treatment are within the above range, the heat treatment time is appropriate, the uniformity of the heat field in the carbonization furnace is relatively high, which is advantageous for improving the uniformity of the formed carbon coating layer, and the irregularity of the crystalline structure of the carbon coating layer is relatively high, approaching amorphous carbon, which is advantageous for improving the kinetic performance of the negative electrode active material.

[0161] In some embodiments, the negative electrode plate may be manufactured in the following manner: The above components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, a dispersant, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, the negative electrode slurry is applied onto a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0162] In some embodiments, the mass fraction of the dispersant in the negative electrode slurry is 0.8%-1.2%.

[0163] Typically, a battery contains a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging of the battery, metal-active ions intermittently

[0164] In some embodiments, the metal-activated ion may be a lithium ion, and the battery may be a lithium-ion battery.

[0165] In some embodiments, the metal-activated ion may be a sodium ion, and the battery may be a sodium-ion battery.

[0166] [Positive electrode plate] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode active material layer is placed on one or both of the two opposing surfaces of the positive electrode current collector.

[0167] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0168] In some embodiments, when the battery is a lithium-ion battery, the positive electrode active material may be a positive electrode active material used in lithium-ion batteries known in the art.

[0169] For example, the positive electrode active material may include at least one of an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may be used. These positive electrode active materials may be used individually or in combination of two or more. Here, examples of lithium transition metal oxides are lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (It can also be abbreviated as LiNi) 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (It can also be abbreviated as LiNi) 0.5 Co 0.25 Mn 0.25 O2(NCM211 (It can also be abbreviated as LiNi) 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (It can also be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (This can also be abbreviated as LiNi)), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.8 Co 0.15 Al 0.05 The material may include, but is not limited to, at least one of O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure may include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), composite materials of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon. The modified compounds for each of the above materials may be used to perform doping modification and / or surface coating modification on the material.

[0170] Batteries undergo the intercalation, deintercalation, and desorption of lithium during the charge-discharge process, and the molar content of lithium differs when the battery is discharged to different states. In the enumeration of positive electrode active materials in this application, the molar content of lithium refers to the initial state of the material, i.e., the state before input, and the molar content of lithium may change after the positive electrode active material is applied to a battery system and undergoes charge-discharge cycles.

[0171] In the enumeration of positive electrode active materials in this application, the molar content of oxygen is only a theoretical value; lattice oxygen release causes a change in the molar content of oxygen, and in reality, a buoyancy occurs in the molar content of oxygen.

[0172] In some embodiments, when the battery is a sodium-ion battery, the positive electrode active material may be a positive electrode active material known in the art and used in sodium-ion batteries.

[0173] For example, the positive electrode active material may include at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue-based sodium compounds, as well as modified compounds of each thereof. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may be used. The modified compounds of each of the above materials may be used to perform doping modification and / or surface coating modification of the material.

[0174] In some embodiments, the transition metal in sodium transition metal oxide may be at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, and Cu. The chemical formula of sodium transition metal oxide is Na x MO2 can be satisfied, where M includes at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, Cu, and 0 <x≦1である。

[0175] In some embodiments, the polyanionic compound is a sodium ion, a transition metal ion, and a tetrahedral (YO4) compound. n- It may be a single compound having an anionic unit. Here, the transition metal may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may include at least one of P, S, and Si, and n is (YO4) n- This represents the valence state of an atom.

[0176] In some embodiments, the polyanionic compound is further a sodium ion, a transition metal ion, or a tetrahedral (YO4) compound. n- It may be a single compound having an anionic unit and a halogen anion. The transition metal may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y may include at least one of P, S, and Si, and n may be (YO4) n- This represents the valence state of the element, and the halogen may contain at least one of F, Cl, and Br.

[0177] In some embodiments, the polyanionic compound is further a sodium ion, tetrahedral (YO4) n- Anion unit, polyhedral unit (ZO y ) m+ and may be a single compound having a selective halogen anion. M may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, Y may include at least one of P, S and Si, and n may be (YO4) n- This represents the valence state, Z represents a transition metal, and m is (ZO y ) m+ This represents the valence state of the element, and the halogen may contain at least one of F, Cl, and Br.

[0178] Examples of polyanionic compounds include those with the chemical formulas NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F (where M' contains at least one of V, Fe, Mn, and Ni), and Na3(VO y )2(PO4)2F 3-2y It can satisfy at least one of the conditions (0 ≤ y ≤ 1).

[0179] In some embodiments, the Prussian blue compound contains sodium ions, transition metal ions, and cyanide ions (CN - It may be one type of compound having ). The transition metal may include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce.

[0180] For example, Prussian blue compounds have the chemical formula Na a Me b Me' c (CN)6 can be satisfied, where Me and Me' each independently contain at least one of Ni, Cu, Fe, Mn, Co, and Zn, 0 <a≦2、0<b<1、0<c<1である。

[0181] Batteries undergo the intercalation, deintercalation, and deconsumption of sodium during the charge-discharge process, and the molar content of sodium differs when the battery is discharged to different states. In the enumeration of positive electrode active materials in this application, the molar content of sodium refers to the initial state of the material, i.e., the state before input, and the molar content of sodium may change as the positive electrode active material is applied to a battery system and undergoes charge-discharge cycles.

[0182] In the enumeration of positive electrode active materials used in sodium-ion batteries in this application, the molar content of oxygen is only a theoretical value, and lattice oxygen release causes a change in the molar content of oxygen, resulting in actual fluctuations in the molar content of oxygen.

[0183] In some embodiments, the positive electrode active material layer further selectively includes an adhesive.

[0184] For example, the adhesive may contain at least one of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0185] In some embodiments, the positive electrode active material layer further selectively comprises a conductive agent.

[0186] For example, the conductive agent may include at least one of the following: superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0187] In some embodiments, the positive electrode plate may be manufactured in the following manner: The components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other component, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then applied onto a positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate is obtained.

[0188] [Electrolytes] The electrolyte plays a role in conducting ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, which may be selected according to the requirements. For example, the electrolyte may be a liquid, a gel, or all-solid.

[0189] In some embodiments, an electrolyte solution is used as the electrolyte. The electrolyte solution contains an electrolyte salt and a solvent.

[0190] In some embodiments, the electrolyte salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethylsulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0191] In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0192] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0193] In some embodiments, the battery further includes a separator. This application is not particularly limited to the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0194] [Separator] In some embodiments, the separator material includes at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0195] The battery described in this application includes battery cell form, battery module form, and battery pack form. The battery cell, battery module, and battery pack of this application will be described below with reference to the drawings as appropriate.

[0196] In some embodiments, the positive electrode plate, negative electrode plate, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0197] In some embodiments, the battery may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0198] In some embodiments, the battery casing may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The battery casing may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and may include, for example, polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0199] This application does not particularly limit the shape of the battery, and it may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a rectangular battery cell 5 as an example.

[0200] In some embodiments, referring to Figure 2, the casing may include a case 51 and a top cover assembly 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing and forming a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the top cover assembly 53 can be fitted over the opening to seal the housing cavity. The positive electrode plate, negative electrode plate and separator may form an electrode assembly 52 through a winding or lamination process. The electrode assembly 52 is packaged within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell may be one or more, and a person skilled in the art can select according to the specific practical requirements.

[0201] In some embodiments, the batteries may be assembled into a battery module, and the number of batteries included in the battery module may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0202] Figure 3 shows an example of a battery module 4. Referring to Figure 3, in the battery module 4, the multiple battery cells 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple battery cells 5 may be fixed together with fasteners.

[0203] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of battery cells 5 are housed.

[0204] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0205] Figures 4 and 5 show an example of a battery pack 1. Referring to Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 being lidable onto the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0206] According to a third aspect of this application, the application provides a power consumption device comprising the aforementioned battery and / or a battery manufactured using the aforementioned method. This power consumption device thus possesses all the features and advantages of the aforementioned battery and manufacturing method, which are not described further here.

[0207] Batteries, battery modules, and battery packs may be used as power sources for power-consuming devices or as energy storage units for power-consuming devices. Power-consuming devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, and energy storage systems.

[0208] As a power consumption device, batteries, battery modules, or battery packs can be selected according to the usage requirements.

[0209] Figure 6 shows an example of a power consumption device. This power consumption device includes pure electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles. To meet the demand for high output and high energy density of the battery in this power consumption device, a battery pack or battery module can be used.

[0210] Other examples of devices may include mobile phones, tablet computers, and laptop computers. These devices generally require a thin profile and may use batteries as a power source.

[0211] The present invention's plan is described and explained below by specific examples. These examples are for illustrative purposes only and should not be considered to limit the scope of this invention. Unless specific technical or conditional details are provided in the examples, they shall be carried out in accordance with the technical or conditional details described in the literature in the art or in accordance with the product description. Unless the manufacturer is specified, the reagents or equipment used are all commonly available commercial products.

[0212] Example 1 Manufacturing of negative electrode active material: It has a volatile content of 4.5% and a true density of 1.40 g / cm³. 3 Needle-shaped coke with a sulfur content of 0.1% is selected as the raw material, and fine powder is removed by crushing, shaping, and a second classification process to obtain primary graphite particles. Here, the supply frequency for the crushing process is 10 Hz, and the classification frequency for the second classification process is 40 Hz.

[0213] Solid asphalt with a caulking value of 67% was selected as the adhesive. The aforementioned graphite primary particles and solid asphalt were mixed in a mass ratio of 7:100, then heated in a high-temperature reaction vessel at 650°C for 2 hours with stirring. After cooling, the mixture was shaped to obtain pre-bonded secondary particles.

[0214] The previously pre - adhered secondary particles were heated at 3000 °C for 48 h in an Acheson graphite furnace, and after cooling, they were subjected to a first classification treatment to obtain secondary particles. Here, the supply frequency of the first classification treatment was 10 Hz, the classification frequency of the first classification treatment was 45 Hz, and the screen mesh number of the first classification treatment was 300 mesh.

[0215] A resin with a coking value of 60% and a viscosity of 500 mPa·s was selected as the liquid - phase coating agent. The above - mentioned secondary particles and the liquid - phase coating agent were put into a mechanical fusion machine at a mass ratio of 3:100 and stirred, and then carbonized at 1100 °C for 15 h to form a carbon - coated layer. After cooling to room temperature, a sieving treatment was carried out to obtain the negative electrode active material.

[0216] Assembling the above - mentioned negative electrode active material into a battery specifically includes the following.

[0217] Negative electrode plate: The negative electrode active material, conductive agent (conductive carbon), stabilizer (sodium carboxymethyl cellulose), and adhesive (SBR) were dispersed in deionized water at a mass ratio of 96.8:0.7:1.2:1.3 to form a negative electrode slurry. The negative electrode slurry was uniformly coated on both side surfaces of the negative electrode current collector copper foil, and the coating weight was 0.160 g / 1540 mm 2 After drying, it was densified by a cold press, and the densification density of the negative electrode film layer was made 1.60 g / cm 3 to this value.

[0218] Positive electrode plate: The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, conductive agent Super - P, and adhesive polyvinylidene fluoride were stirred at a mass ratio of 97.4:1.5:1.1 and dispersed in N - methylpyrrolidone to produce a positive electrode slurry. It was coated on the aluminum foil of the positive electrode current collector, and the coating weight was 0.238 g / 1540 mm 2 After densifying with a cold press, it was cut to obtain a positive electrode plate, and the densification density of the positive electrode plate was 3.5 g / cm 3 to this value.

[0219] Separator: A polyethylene porous membrane with a thickness of 12 μm was selected.

[0220] Electrolyte: At 25°C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain a mixed solvent. LiPF6 is then dissolved in this mixed solvent to obtain the electrolyte, where the concentration of LiPF6 is 1 mol / L.

[0221] Battery assembly: The manufactured negative electrode plate, separator, and positive electrode plate were stacked in order, with the separator positioned between the positive and negative electrode plates to provide isolation, and then wound up to obtain a bare cell. This was then inserted into a battery housing, and the battery was obtained through processes such as firing, liquid injection, standing, packaging, chemical conversion, and volume division.

[0222] Example 2 Example 2 is the same as Example 1, the only difference being that the supply frequency for the first classification process is 5 Hz.

[0223] Example 3 Example 3 is the same as Example 2, the only difference being that the classification frequency of the first classification process is 30 Hz.

[0224] Example 4 Example 4 is the same as Example 3, the only difference being that the caulking value of the liquid phase coating agent is 45%.

[0225] Example 5 Example 5 is the same as Example 4, the only difference being that the viscosity of the liquid phase coating agent is 225 mPa·s.

[0226] Comparative Example 1 Comparative Example 1 is the same as Example 1, the only difference being that the first classification process is omitted.

[0227] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the first classification treatment is not performed, asphalt is used as the solid-phase coating agent to form a carbon coating layer, the coking value of the solid-phase coating agent is 60%, and the softening point is 200°C.

[0228] Comparative Example 3 Comparative Example 3 is the same as Example 3, the only difference being that in Comparative Example 3, the carbon coating layer is formed using the solid-phase coating agent from Comparative Example 2.

[0229] The following tests were performed on the negative electrode active materials in the aforementioned examples and comparative examples, and the test results are shown in Table 1.

[0230] Oil absorption value: 100g of negative electrode active material was placed in the supply port of the oil absorption value tester, and dibutyl phthalate was automatically titrated onto the negative electrode active material by the instrument until it became a semi-plastic aggregate. The amount of dibutyl phthalate added at this time (a mL) was recorded, and the oil absorption value of this negative electrode active material was determined to be a mL / 100g.

[0231] Secondary particle ratio: The negative electrode active material was laid and bonded to a conductive adhesive to prepare a sample measuring 6 cm × 1.1 cm in length × width, and the particle morphology was tested using a scanning electron microscope (e.g., ZEISS Sigma 300). The test can be referred to in JY / T010-1996. To ensure the accuracy of the test results, multiple (e.g., 20) different areas were randomly selected from the sample to be tested and scanned. At a constant magnification rate (e.g., 1000x), the percentage of secondary particles in each test area relative to the total number of particles was calculated, i.e., the proportion of secondary particles in that area. The average value of the test results from multiple test areas was taken to determine the proportion of secondary particles in the negative electrode active material.

[0232] Processing performance: The negative electrode active material, conductive agent (conductive carbon), stabilizer (sodium carboxymethyl cellulose), and adhesive (SBR) are dispersed in deionized water at a mass ratio of 96.8:0.7:1.2:1.3 to form a negative electrode slurry. Take 500 mL of the negative electrode slurry and filter it through a 150-mesh stainless steel mesh, and record the time required to obtain 300 mL of the slurry after filtration. The shorter the time, the easier it is to filter the slurry, indicating higher processing performance.

[0233] The following tests were conducted on the batteries in the above-described examples and comparative examples, and the test results are as shown in Table 1.

[0234] 25°C rapid charging ability test: Place the manufactured battery under room temperature conditions of 25°C, perform constant current charging at a rate of 0.33C until it reaches 4.25V, then perform constant voltage charging until the current reaches 0.05C, leave it for 5 minutes, and then discharge it at 0.33C until it reaches 2.5V. Record the constant current discharge capacity as the initial capacity C0. Charge the battery in sequence at constant currents of 0.5 C0, 1 C C0, 1.5 C0, 2 C0, 2. C0, 3 C0, 3.5 C0 until the full cell potential reaches 4.25V or the negative electrode cut-off potential reaches 0 mV (reaching either one of these conditions indicates that the charging is complete). After each charging is complete, discharge it at 0. C0 until it reaches 2.5V. Record the corresponding negative electrode potential at different charging rates every 10% SOC (10% SOC - 80% SOC), draw the rate-negative electrode potential curve at different SOCs, and after linear fitting, obtain the charging rate corresponding to the case where the negative electrode potential at different SOCs is 0 mV, and denote it as C x (x = 2 - 8). Based on the formula (1 / C2 + 1 / C3 + 1 / C4 + 1 / C5 + 1 / C6 + 1 / C7 + 1 / C8) × 0.1 × 60, calculate and obtain the charging time T (min) for the battery to charge from 10% SOC to 80% SOC. The shorter this time, the better the rapid charging performance of the battery.

[0235] Cycle performance (45°C 1C / 1C, 1000 cycles, capacity retention rate): At 45°C, the battery is charged with a constant current of 0.33C until the cutoff voltage reaches 4.25V, then charged with a constant voltage until the current reaches 0.05C, left standing for 5 minutes, and then discharged with a constant current of 0.33C until the cutoff voltage reaches 2.5V. The initial capacity is recorded as C0. Next, the battery is charged at a rate of 1 C0 and discharged at 1 C0, and the discharge capacity C for each cycle is recorded. n (where n is the number of cycles, n = 1-1000) is recorded, and after 1000 cycles, the cycle capacity retention rate (i.e., C) is recorded. 1000 Calculate ( / C0 × 100%). A higher cycle maintenance rate indicates a better lifespan.

[0236] [Table 1]

[0237] Referring to Figure 7, the scanning electron microscope image of the negative electrode active material in Example 1 shows that the surface irregularities of the negative electrode active material in Comparative Example 1 are relatively few, and the oil absorption value is relatively low. Referring to Figure 8, the scanning electron microscope image of the negative electrode active material in Comparative Example 1 shows that the surface of the negative electrode active material in Comparative Example 1 has a relatively large number of irregularities, and the oil absorption value is relatively high.

[0238] As can be seen from the test results, Examples 1-5 effectively remove fine particles from the powder through a first classification process during the manufacturing process of the negative electrode active material. The oil absorption value of the negative electrode active material after liquid phase coating is relatively low. The negative electrode active material combines a relatively high proportion of secondary particles with a relatively low oil absorption value, thereby significantly improving the rate performance and processing performance of the negative electrode active material. Furthermore, compared to solid phase coatings, liquid phase coatings have relatively high fluidity, spread more uniformly on the surface of secondary particles, and have a better coating effect. They also provide constraint and buffering effects against the volume expansion of graphite, thereby improving the cycle stability of the negative electrode active material.

[0239] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are merely illustrative, and any embodiments that have substantially the same configuration as the technical idea and produce the same effects within the scope of the technical proposal of this application are included within the scope of the technical proposal. Furthermore, other methods that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive of, and by combining some of the components of the embodiments, are also included within the scope of this application, without departing from the spirit of this application. [Explanation of symbols]

[0240] 1. Battery pack, 2. Upper casing, 3. Lower casing, 4. Battery module, 5. Battery cell 51 Housing, 52 Electrode assembly, 53 Top cover assembly.

Claims

1. A battery comprising a positive electrode plate, a negative electrode plate, and a separator, wherein the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer located on at least one side of the negative electrode current collector, the negative electrode active material layer includes a negative electrode active material, the negative electrode active material includes graphite, the proportion of secondary particles in the negative electrode active material is 65% or more, the oil absorption value of the negative electrode active material is 40 mL / 100 g to 65 mL / 100 g, and the volume distribution particle size Dv1 of the negative electrode active material is 4 μm to 8 μm.

2. The battery according to claim 1, wherein the negative electrode active material satisfies the condition that (Dv90 - Dv10) / Dv50 is between 0.8 and 1.

2.

3. The battery according to claim 2, wherein the volume distribution particle size Dv10 of the negative electrode active material is 7 μm to 11 μm, and / or the volume distribution particle size Dv90 of the negative electrode active material is 20 μm to 30 μm, and / or the volume distribution particle size Dv50 of the negative electrode active material is 12 μm to 18 μm.

4. The battery according to any one of claims 1 to 3, wherein the degree of graphitization of the negative electrode active material is 93%-95%.

5. The specific surface area of ​​the negative electrode active material is 2.5 m². ２ / g-3.5m ２ A battery according to any one of claims 1 to 3, wherein the value is / g.

6. The battery according to any one of claims 1 to 3, wherein the negative electrode active material further comprises a carbon coating layer, the carbon coating layer is located on the surface of at least a portion of the secondary particles, the secondary particles are formed by bonding at least two primary particles together, and the bonding material comprises a carbon material.

7. The battery according to any one of claims 1 to 3, wherein the porosity of the negative electrode active material layer is 18% to 35%.

8. The compaction density of the negative electrode active material layer is 1.60 g / cm³. ３ -1.75 g / cm ３ The battery according to any one of claims 1 to 3.

9. The process involves mixing primary graphite particles with an adhesive and performing a first heat treatment to obtain pre-bonded secondary particles. The aforementioned pre-bonded secondary particles are subjected to a second heat treatment and a first classification treatment to obtain secondary particles and a negative electrode active material. A method for manufacturing a battery according to any one of claims 1 to 8, comprising: placing the negative electrode active material on one side of the negative electrode current collector to obtain a negative electrode plate; and assembling the negative electrode plate, separator, and positive electrode plate to obtain a battery.

10. Providing the aforementioned graphite primary particles involves performing a crushing process and a second classification process on a raw material containing at least one of petroleum raw coke and needle coke raw coke to obtain the aforementioned graphite primary particles. Providing the aforementioned graphite primary particles is, The volatile content in the aforementioned raw material is 4%-7%, The true density of the aforementioned raw material is 1.35 g / cm³. ３ -1.50 g / cm ３ The conditions are, The sulfur content of the aforementioned raw material is 2% or less, The supply frequency for the aforementioned grinding process is set to 10 Hz - 35 Hz. The method according to claim 9, wherein the classification frequency of the second classification process satisfies at least one of the following conditions: 30 Hz - 50 Hz.

11. The adhesive comprises at least one of asphalt and resin, and the adhesive is The caulking value of the aforementioned adhesive is under the condition that it is 60%-70%, The mass ratio of the adhesive to the graphite primary particles is (7-10):100, The method according to claim 9 or 10, wherein the particle size of the adhesive satisfies at least one of the following conditions: 4 μm - 8 μm.

12. The method according to claim 9 or 10, wherein the temperature of the first heat treatment is 600°C to 800°C, and the duration of the first heat treatment is 1 hour to 4 hours.

13. The method according to claim 9, wherein the temperature of the second heat treatment is 2800°C to 3300°C, and the duration of the second heat treatment is 36h to 72h.

14. The first classification process described above is: The condition for the number of screen meshes in the first classification process is 300 mesh - 350 mesh, The supply frequency for the first classification process is 4 Hz - 10 Hz, The method according to claim 9, wherein the classification frequency of the first classification process satisfies at least one of the following conditions: 30 Hz - 50 Hz.

15. After obtaining the aforementioned secondary particles, The method according to claim 9, further comprising mixing the secondary particles with a liquid phase coating agent and performing a third heat treatment to form a carbon coating layer on a portion of the secondary particles, wherein the liquid phase coating agent comprises at least one of asphalt and resin having a viscosity of 500 mPa·s or less.

16. The method according to claim 15, wherein the mass ratio of the liquid phase coating agent to the secondary particles is (2-10):100, and / or the coking value of the liquid phase coating agent is 40%-70%.

17. The method according to claim 15 or 16, wherein the temperature of the third heat treatment is 1000°C to 1200°C, and the duration of the third heat treatment is 15h to 30h.

18. A power consumption device comprising a battery according to any one of claims 1 to 8, or a battery manufactured using the method described in any one of claims 9 to 17.

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