Secondary batteries, power consumption devices

Abstract

The present application relates to a secondary battery and a power consumption device. The secondary battery includes a negative electrode plate, the negative electrode plate including a negative electrode current collector and a negative electrode film layer formed on at least one surface of the negative electrode current collector, the negative electrode film layer including a lower region and an upper region, the lower region including a first negative electrode active material, and the upper region including a second negative electrode active material, and the median of the Raman values ​​ID / IG of the first negative electrode active material is defined as R1 50 The median value of the Raman values ​​ID / IG of the second negative electrode active material is expressed as R2 50 and the above R1 50 is the R2 50 and the degree of graphitization of the first negative electrode active material is greater than the degree of graphitization of the second negative electrode active material. This design is advantageous for improving the rapid charging performance and energy density of the secondary battery.

Description

[Technical Field]

[0001] cross reference This application claims priority to a Chinese patent application for invention bearing application number 202410046330.8, filed on January 12, 2024, and entitled "Secondary Battery, Power Consumption Device," the contents of which are incorporated herein by reference.

[0002] Technical Field The present application relates to secondary batteries, power consuming devices. [Background technology]

[0003] In recent years, with the development of lithium-ion secondary battery technology, lithium-ion secondary batteries have been widely used in energy storage 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, electric vehicles, military equipment, aerospace, etc. Due to their rapid development, lithium-ion secondary batteries are also required to have higher energy density and fast charging performance. Summary of the Invention

[0004] The object of the present application is to provide a secondary battery, a power consuming device.

[0005] An embodiment of the present application is realized as follows.

[0006] According to a first aspect, an embodiment of the present application provides a secondary battery including a negative electrode plate, the negative electrode plate including a negative electrode current collector and a negative electrode film layer formed on at least one surface of the negative electrode current collector, the negative electrode film layer including a lower region and an upper region, the lower region including a first negative electrode active material, and the upper region including a second negative electrode active material, and the median of the Raman values ​​ID / IG of the first negative electrode active material is defined as R1 50 The median value of the Raman values ​​ID / IG of the second negative electrode active material is expressed as R2 50 and the above R1 50 is the R2 50and the degree of graphitization of the first negative electrode active material is greater than the degree of graphitization of the second negative electrode active material.

[0007] The above technical solution controls the Raman coefficient ID / IG of the first negative electrode active material in the negative electrode film layer close to the negative electrode current collector (i.e., the lower region) to be relatively low, and the Raman coefficient ID / IG of the second negative electrode active material in the negative electrode film layer away from the negative electrode current collector (i.e., the upper region) to be relatively high, and the graphitization degree of the first negative electrode active material to be greater than the graphitization degree of the second negative electrode active material, thereby achieving both an improvement in the fast charging performance of the lithium-ion battery and an improvement in the energy density of the lithium-ion battery.

[0008] In some alternative implementations, R1 50 is 0.05 to 0.15, and optionally, R1 50 is between 0.05 and 0.1, and / or R2 50 is 0.20 to 0.40, and selectively, R2 50 is 0.25 to 0.35.

[0009] The above technical solutions can work synergistically together by controlling the median Raman value ID / IG of the first negative electrode active material in the negative electrode film layer close to the negative electrode current collector to be relatively low, and the median Raman value ID / IG of the second negative electrode active material in the negative electrode film layer away from the negative electrode current collector to be relatively high, thereby improving the fast charging performance of lithium-ion batteries while also improving the energy density of lithium-ion batteries.

[0010] In some alternative embodiments, the graphitization degree of the first negative electrode active material is ≧92%, and optionally 93% to 95%; and / or The graphitization degree of the second negative electrode active material is ≧91%, and optionally 92% to 94%.

[0011] In the above technical solution, the graphitization degree of the first negative electrode active material is greater than or within the above range than the graphitization degree of the second negative electrode active material, which is advantageous to improving the energy density of the lithium ion battery and, at the same time, the fast charging performance of the lithium ion battery.

[0012] In some alternative embodiments, the powder compaction density of the first negative electrode active material is greater than the powder compaction density of the second negative electrode active material.

[0013] In some alternative embodiments, the first negative electrode active material has a powder compaction density of ≥ 1.95 g / cm when tested at a pressure of 49000 N. 3 and selectively 1.96 g / cm 3 ~1.99g / cm 3 and / or The second negative electrode active material has a powder compaction density of 1.81 g / cm when tested at a pressure of 49,000 N. 3 ~1.87g / cm 3 and selectively 1.82 g / cm 3 ~1.86g / cm 3 is.

[0014] The above technical proposal can improve the rapid charging performance of the lithium-ion battery while also improving the energy density of the lithium-ion battery by setting the powder compaction density of the first negative electrode active material to be greater than or within the above range than the powder compaction density of the second negative electrode active material.

[0015] In some alternative embodiments, the powder OI of the first negative active material is greater than the powder OI of the second negative active material.

[0016] In some alternative embodiments, the first negative electrode active material powder OI is 2.0 to 10.0, and optionally 4.0 to 8.0; and / or The powder OI of the second negative electrode active material is 1.0 to 8.0, and optionally 2.5 to 5.5.

[0017] In the above technical solution, the OI of the first negative electrode active material powder is greater than or within the above range than the OI of the second negative electrode active material powder, which is advantageous for improving the energy density of the lithium ion battery and at the same time, for improving the fast charging performance of the lithium ion battery.

[0018] In some alternative embodiments, the tap density of the first negative electrode active material is less than the tap density of the second negative electrode active material.

[0019] In some alternative embodiments, the tap density of the first negative electrode active material is ≥ 0.8 g / cm 3 and selectively 0.9 g / cm 3 ~1.1g / cm 3 and / or The specific surface area of ​​the second negative electrode active material is 3.0 m 2 / g~4.3m 2 / g, and selectively 3.2m 2 / g~4.0m 2 / g.

[0020] In the above technical solution, the tap density of the first negative electrode active material is smaller than or within the above range than the tap density of the second negative electrode active material, which can more effectively improve the energy density of the lithium ion battery and is also advantageous for improving the fast charging performance of the lithium ion battery.

[0021] In some alternative embodiments, the volume distribution particle size Dv1 of the first negative electrode active material is smaller than the volume distribution particle size Dv1 of the second negative electrode active material.

[0022] In some alternative embodiments, the volume distribution particle size Dv1 of the first negative electrode active material is 1.0 μm to 8.0 μm, and optionally 3.0 μm to 5.0 μm; and / or The volume distribution particle size Dv1 of the second negative electrode active material is 3.5 μm to 10.0 μm, and optionally 5.5 μm to 8.0 μm.

[0023] In some alternative embodiments, the volume distribution particle size Dv50 of the first negative electrode active material is greater than the volume distribution particle size Dv50 of the second negative electrode active material.

[0024] In some alternative embodiments, the volume distribution particle size Dv50 of the first negative electrode active material is 10 μm to 20 μm, and optionally 15 μm to 16.5 μm; The volume distribution particle size Dv50 of the second negative electrode active material is 10 μm to 20 μm, and optionally 13 μm to 14.5 μm.

[0025] In some alternative embodiments, the particle size distribution (D V 90-D V 10) / D V 50 is the particle size distribution (D V 90-D V 10) / D V Greater than 50.

[0026] In some alternative embodiments, the particle size distribution (D V 90-D V 10) / D V 50 is ≦2.0, and optionally 1.2 to 1.8; The particle size distribution (D V 90-D V 10) / D V 50 is ≦1.8, and optionally 1.0 to 1.6.

[0027] The above technical proposal is based on the particle size distribution (D V 90-D V 10) / D V 50 is the particle size distribution (D V 90-D V 10) / D V By setting the particle size to be greater than 50, a good normal particle size distribution can be formed, which is advantageous for improving the energy density of the lithium ion battery and at the same time, is advantageous for improving the fast charging performance of the lithium ion battery.

[0028] In some alternative embodiments, the specific surface area of ​​the first negative electrode active material is smaller than the specific surface area of ​​the second negative electrode active material.

[0029] In some alternative embodiments, the specific surface area of ​​the first negative electrode active material is 0.5 m 2 / g~3.0m 2 / g, and selectively 1.0m 2 / g~2.5m 2 / g, and / or The specific surface area of ​​the second negative electrode active material is 2.5 m 2 / g~4.4m 2 / g, and selectively 3.0m 2 / g~4.0m 2 / g.

[0030] In some alternative embodiments, the first negative electrode active material is (1) D of the first negative electrode active material V 10 is 5 μm to 9 μm, and optionally 5.8 μm to 7.8 μm; (2) D of the first negative electrode active material V 90≦30 μm, and optionally 20 μm to 30 μm; (3) D of the first negative electrode active material V 99≦40 μm, and optionally 30 μm to 40 μm; (4) The gram capacity of the first negative electrode active material is 355 mAh / g to 365 mAh / g, and optionally 357 mAh / g to 363 mAh / g.

[0031] In some alternative embodiments, the second negative electrode active material is (1) D of the second negative electrode active material V 10 is 6 μm to 10.0 μm, and optionally 7.5 μm to 9.0 μm; (2) D of the second negative electrode active material V 90≦30 μm, and optionally 20 μm to 30 μm; (3) D of the second negative electrode active material V 99≦40 μm, and optionally 30 μm to 40 μm; (4) The gram capacity of the second negative electrode active material is 352mAh / g to 362mAh / g, and optionally 354mAh / g to 360mAh / g; (5) At least a part of the surface of the second negative electrode active material has a carbon coating layer.

[0032] In some alternative embodiments, the first negative electrode active material and / or the second negative electrode active material are both artificial graphite.

[0033] In some alternative embodiments, the compaction density of the negative electrode film layer is 1.25 g / cm 3 or more, and optionally 1.28 g / cm 3 ~1.65g / cm 3 and / or The coating weight per unit area of ​​the negative electrode film layer is 0.075 mg / mm 2 or more, and selectively 0.08 mg / mm 2 ~0.11mg / mm 2 is.

[0034] According to a second aspect, an embodiment of the present application provides a power consuming device including a secondary battery according to the first aspect. [Brief explanation of the drawings]

[0035] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments. It should be understood that the following drawings only illustrate some embodiments of the present application, and should not be considered as limiting the scope. Those skilled in the art can also obtain other related drawings based on these drawings without exerting any creative efforts.

[0036] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a negative electrode plate of the present application. [Figure 2] FIG. 2 is a schematic diagram of another embodiment of the negative electrode plate of the present application. [Figure 3] FIG. 2 is a schematic diagram of yet another embodiment of the negative electrode plate of the present application. [Figure 4] 1 is a schematic diagram of a battery cell according to an embodiment of the present application. [Figure 5] FIG. 5 is an exploded view of the battery cell of one embodiment of the present application shown in FIG. 4. [Figure 6] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 7] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 8] FIG. 8 is an exploded view of the battery pack shown in FIG. 7 according to an embodiment of the present application. [Figure 9] 1 is a schematic diagram of a power consumption device powered by a secondary battery according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the secondary battery and electric device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or repeated description of actually identical structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the scope of the claims.

[0038] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, with the selected lower and upper limits defining the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand notation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" in this specification, and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0039] Unless otherwise stated, all embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0040] Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0041] Unless otherwise specified, all steps in this application may be performed in order or randomly, but are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0042] The negative electrode has a certain effect on the energy density and fast charging capability of a battery, and it has been surprisingly discovered that by controlling the negative electrode of the present application, a secondary battery having both high energy density and fast charging characteristics can be obtained.

[0043] Based on this, a first aspect of the present application provides a secondary battery that can achieve both an improvement in the rapid charging performance of the battery and an improvement in the energy density of the battery.

[0044] The term "secondary battery" referred to in this specification refers to a battery cell, a battery module, or a battery pack.

[0045] A typical secondary battery cell includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging, active ions shuttle between the positive and negative electrodes, absorbing and desorbing. The electrolyte serves to conduct ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes and allows ions to pass through.

[0046] [Negative electrode plate] The secondary battery includes a negative electrode plate, and the negative electrode plate includes a negative electrode current collector and a negative electrode film layer formed on at least one surface of the negative electrode current collector.

[0047] The negative electrode film layer has a first surface adjacent to the negative electrode current collector and a second surface disposed opposite the first surface, and a region of the negative electrode film layer extending from the first surface to a certain thickness in the thickness direction constitutes a lower region, and a region of the negative electrode film layer extending from the second surface to a certain thickness in the thickness direction constitutes an upper region.

[0048] The thickness of the negative electrode film layer is denoted as H, and the thickness of the lower region can be any value within the range of 0.1H to 0.9H. For example, the thickness of the lower region can be 0.1H, 0.2H, 0.3H, 0.4H, 0.5H, 0.6H, 0.7H, 0.8H, or 0.9H.

[0049] The thickness of the upper region can be any value within the range of 0.1H to 0.9H, and for example, the thickness of the upper region can be 0.1H, 0.2H, 0.3H, 0.4H, 0.5H, 0.6H, 0.7H, 0.8H, or 0.9H.

[0050] Optionally, the negative electrode film layer further includes an intermediate region.

[0051] 1 to 3, schematic diagrams of several different specific embodiments of the negative electrode plate of the present application are shown. As shown in FIGS. 1 to 3, the negative electrode plate 10 includes a negative electrode current collector 101 and a negative electrode film layer 102 formed on at least one surface of the negative electrode current collector 101. The negative electrode film layer 102 has a first surface 102b adjacent to the negative electrode current collector 101 and a second surface 102a opposite the first surface 102b. The thickness of the negative electrode film layer 102 is denoted as H. The thickness H of the negative electrode film layer is the thickness of the negative electrode film layer located on one side of the negative electrode current collector. The region of the negative electrode film layer within a certain thickness range (e.g., 0.3H) from the second surface 102a to the negative electrode film layer is denoted as an upper region 1022 of the negative electrode film layer. The region of the negative electrode film layer within a certain thickness range (e.g., 0.3H) from the first surface 102b to the negative electrode film layer is denoted as a lower region 1021 of the negative electrode film layer. The lower region 1021 includes a first negative electrode active material, and the upper region 1022 includes a second negative electrode active material. A region between the upper region 1022 and the lower region 1021 and occupying a range of thickness 0.4H is referred to as an intermediate region 1023. As can be easily understood from FIGS. 1 to 3 , the range of the intermediate region 1023 may include only the first negative electrode active material, only the second negative electrode active material, or both the first and second negative electrode active materials.

[0052] 1 to 3, the first surface 102b is in contact with the top surface of the negative electrode current collector 101, but the structure of the negative electrode plate of the present application is not limited thereto. For example, there may be an additional layer between the negative electrode film layer 102 and the negative electrode current collector 101. In this case, the first surface 102b is not in direct contact with the negative electrode current collector 101.

[0053] Specifically, FIGS. 1 to 3 show that the first and second negative electrode active materials are sequentially applied onto the negative electrode current collector 101. FIG. 1 shows that the thicknesses of the lower and upper regions each account for approximately half of the thickness of the negative electrode film layer 102. FIG. 2 shows that the thickness of the upper region accounts for approximately 30% of the thickness of the negative electrode film layer 102, and the thickness of the lower region accounts for approximately 70% of the thickness of the negative electrode film layer 102. FIG. 3 shows a configuration opposite to that of FIG. 2, i.e., the thickness of the lower region accounts for approximately 30% of the thickness of the negative electrode film layer 102, and the thickness of the upper region accounts for approximately 70% of the thickness of the negative electrode film layer 102.

[0054] It should be understood that Figures 1 to 3 are schematic diagrams of ideal situations. The present application does not particularly limit the thickness ratio of the lower region to the upper region, and for example, the ratio can be any ratio ranging from 1:9 to 9:1. Illustratively, the thickness ratio of the lower region to the upper region can be 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, etc., or a ratio between any two ratios.

[0055] It should further be understood that although Figures 1-3 show clear boundaries between regions, such clear interfaces may not exist in the product.

[0056] In the present application, the median of the Raman values ​​ID / IG of the first negative electrode active material is R1 50 The median of the Raman values ​​ID / IG of the second negative electrode active material is expressed as R2 50 and R1 50 is R2 50 In the above technical proposal, the median value of the Raman value ID / IG represents the degree of disorder on the entire surface of the material. The smaller the median value of the Raman value ID / IG, the smaller the degree of disorder on the entire surface of the material, and the smaller the median value of the Raman value ID / IG of the material, the more favorable the energy density.

[0057] In some embodiments of the present application, the first negative electrode active material may be selected from highly anisotropic raw materials or highly graphitized materials produced by a high-temperature graphitization process, for example, acicular coke graphite fluorinated rings, petroleum coke graphite fluorinated rings, etc.

[0058] In some embodiments of the present application, the second negative electrode active material may be a graphite material with a relatively high degree of disorder to obtain a second negative electrode active material with a relatively large median Raman value I / I. Alternatively, the second negative electrode active material may be produced by selecting a process for coating graphite with a highly disordered coating layer, e.g., by coating graphite with a hard carbon coating layer.

[0059] Furthermore, in the above technical solution, the median value of the Raman coefficient ID / IG of the first negative electrode active material in the lower region is relatively low, which is advantageous to the energy density of the battery.

[0060] Furthermore, a larger median Raman value, ID / IG, indicates a greater degree of disorder across the material surface, which favors ionic charge exchange at the surface of the negative electrode active material.

[0061] In the above technical solution, the median Raman coefficient ID / IG of the second negative electrode active material in the upper region is relatively high, which is favorable for charge exchange on the surface of the negative electrode active material, thereby improving the dynamic performance.

[0062] Furthermore, in some embodiments of the present application, the median Raman values ​​I / I of the second negative electrode active material are not only greater than but also uniformly distributed, which is more favorable for lithium ion transport and kinetic performance.

[0063] Furthermore, in some embodiments of the present application, the degree of graphitization of the first negative electrode active material is greater than the degree of graphitization of the second negative electrode active material.

[0064] In the present application, by controlling the first negative electrode active material in the lower region to have a relatively low median Raman value I D / I G and the second negative electrode active material in the upper region to have a relatively high median Raman value I D / I G , and by controlling the degree of graphitization of the first negative electrode active material to be greater than the degree of graphitization of the second negative electrode active material, it is possible to improve the fast charging performance of the lithium ion battery while simultaneously improving the energy density of the lithium ion battery.

[0065] Furthermore, in some embodiments of the present application, the above R1 50 is 0.05 to 0.15.

[0066] Further optionally, illustratively, in some embodiments of the present application, the above R 50 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15 or a range between any two of the aforementioned values.

[0067] In the above technical proposal, R1 50 By setting the value to 0.05 to 0.15, the R2 50 This allows for improved rapid charging performance of lithium-ion batteries while also improving their energy density.

[0068] Further optionally, in some embodiments of the present application, R1 50 is 0.05 to 0.10.

[0069] Illustratively, in some embodiments of the present application, the above R 50 is 0.05, 0.06, 0.07, 0.08, 0.09 or 0.10.

[0070] In the above technical proposal, R1 50 If is limited to the range of 0.05 to 0.10, it is more advantageous to simultaneously improve the rapid charging performance of the lithium ion battery and improve the energy density of the lithium ion battery.

[0071] Furthermore, in some embodiments of the present application, R2 50 is 0.20 to 0.40.

[0072] Illustratively, in some embodiments of the present application, the above R2 50 is 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.28, 0.30, 0.35, 0.38, 0.39, 0.40 or a range between any two of the foregoing values.

[0073] In the above technical proposal, R2 50 By setting R1 to 0.20 to 0.40, 50 This allows for improved rapid charging performance of lithium-ion batteries while also improving their energy density.

[0074] Further optionally, in some embodiments of the present application, R2 50 is 0.25 to 0.35.

[0075] For example, R2 50 is 0.25, 0.26, 0.28, 0.31, 0.32 or 0.35.

[0076] In the above technical proposal, R2 50 By limiting the value of β to the range of 0.25 to 0.35, it is more advantageous to improve the rapid charging performance of the lithium ion battery while simultaneously improving the energy density of the lithium ion battery.

[0077] Furthermore, in some embodiments of the present application, the degree of graphitization of the first negative electrode active material is ≧92%, and optionally 93-95%.

[0078] In the above technical solution, the graphitization degree of the first negative electrode active material is set to be ≧94%, which can more effectively improve the energy density of the lithium ion battery and is also advantageous for improving the fast charging performance of the lithium ion battery.

[0079] Further optionally, in some optional embodiments of the present application, the graphitization degree of the first negative electrode active material is 92%, 93%, 94%, 95%, or a range between any two of the aforementioned values.

[0080] Furthermore, in some embodiments of the present application, the graphitization degree of the second negative electrode active material is ≧91%, and optionally 92 to 94%.

[0081] In the above technical solution, the graphitization degree of the second negative electrode active material is set to be 91% or more, which can more effectively improve the energy density of the lithium ion battery and is also advantageous to improving the fast charging performance of the lithium ion battery.

[0082] Further optionally, in some optional embodiments of the present application, the graphitization degree of the second negative electrode active material is 91%, 92%, 93%, 94%, or a range between any two of the aforementioned values.

[0083] Furthermore, in some embodiments of the present application, the powder compaction density of the first negative electrode active material is greater than the powder compaction density of the second negative electrode active material.

[0084] The fact that the powder compaction density of the first negative electrode active material is greater than that of the second negative electrode active material indicates that the compaction density of the lower region of the negative electrode film layer is higher and the compaction density of the upper region of the negative electrode film layer is lower, resulting in dense particle deposition in the lower region of the negative electrode film layer, fully utilizing the high-density, high-capacity characteristics of the active materials and ensuring the energy density of the film layer. The upper region of the negative electrode film layer has a relatively low compaction density, resulting in abundant voids, which provides sufficient paths for lithium ions to travel within the electrode plate and ensures the fast charging capability of the film layer.

[0085] In the above technical proposal, by setting the powder compaction density of the first negative electrode active material to be greater than the powder compaction density of the second negative electrode active material, it is possible to improve the rapid charging performance of the lithium ion battery while also improving the energy density of the lithium ion battery.

[0086] Furthermore, in some embodiments of the present application, the first negative electrode active material has a powder compaction density tested at a pressure of 49000 N of ≥ 1.95 g / cm 3 and selectively 1.96 g / cm 3 ~1.99g / cm 3 is.

[0087] Illustratively, in some embodiments of the present application, the first negative electrode active material has a powder compaction density of 1.96 g / cm 3 when tested at a pressure of 49000 N. 3 , 1.97g / cm 3 , 1.98g / cm 3 , 1.99g / cm 3 is.

[0088] Furthermore, in some embodiments of the present application, the second negative electrode active material has a powder compaction density of 1.81 g / cm when tested at a pressure of 49000 N. 3 ~1.87g / cm 3 and selectively 1.82 g / cm 3 ~1.86g / cm 3 is.

[0089] Illustratively, in some embodiments of the present application, the second negative electrode active material has a powder compaction density of 1.81 g / cm 3 when tested at a pressure of 49000 N. 3 , 1.82g / cm 3 , 1.83g / cm 3 , 1.84g / cm 3 , 1.85g / cm 3 or 1.86 g / cm 3 is.

[0090] Furthermore, in some embodiments of the present application, the powder OI of the first negative electrode active material is greater than the powder OI of the second negative electrode active material.

[0091] Furthermore, in some embodiments of the present application, the OI of the first negative electrode active material is 4.0 to 8.0.

[0092] In some embodiments of the present application, the powder OI of the second negative electrode active material is 1.0 to 8.0.

[0093] The OI in the above technical solution refers to the voltage during the discharge process of the first or second negative electrode active material. The OI value of the first or second negative electrode active material directly affects the energy density of the lithium ion battery.

[0094] In the above technical solution, the OI of the first negative electrode active material is set to 4.0-8.0, and the OI of the second negative electrode active material powder is set to 1.0-8.0, which is advantageous for improving the energy density of the lithium ion battery and at the same time, the fast charging performance of the lithium ion battery.

[0095] Illustratively, in some embodiments of the present application, the OI of the first negative electrode active material is 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, or a range between any two of the aforementioned values.

[0096] Illustratively, in some embodiments of the present application, the OI of the second negative electrode active material is 1.0, 2.0, 3.0, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, or a range between any two of the aforementioned values.

[0097] Furthermore, in some embodiments of the present application, the tap density of the first negative electrode active material is less than the tap density of the second negative electrode active material.

[0098] Furthermore, in some embodiments of the present application, the tap density of the first negative electrode active material is ≥ 0.8 g / cm 3 and selectively 0.9 g / cm 3 ~1.1g / cm 3 is.

[0099] Furthermore, in some embodiments of the present application, the specific surface area of ​​the second negative electrode active material is 3.0 m 2 / g~4.3m 2 / g, and selectively 3.2m 2 / g~4.0m 2 / g.

[0100] Furthermore, in the above technical solution, by setting the tap density of the first or second negative electrode active material within the above range, the energy density of the lithium ion battery can be effectively improved, and at the same time, it is advantageous to improve the fast charging performance of the lithium ion battery.

[0101] Illustratively, in some embodiments of the present application, the tap density of the first negative electrode active material is 0.9 g / cm 3 , 1g / cm 3 or 1.1 g / cm 3 The specific surface area of ​​the second negative electrode active material is 3.0 m 2 / g, 3.2m 2 / g, 3.5m 2 / g, 3.8m 2 / g or 4.0m 2 / g.

[0102] Furthermore, in some embodiments of the present application, the volume distribution particle size Dv1 of the first negative electrode active material is smaller than the volume distribution particle size Dv1 of the second negative electrode active material.

[0103] Furthermore, in some embodiments of the present application, the volume distribution particle size Dv1 of the first negative electrode active material is 1.0 μm to 8.0 μm, and optionally 3.0 μm to 5.0 μm.

[0104] Furthermore, in some embodiments of the present application, the volume distribution particle size Dv1 of the second negative electrode active material is 3.5 μm to 10.0 μm, and optionally 5.5 μm to 8.0 μm.

[0105] Illustratively, in some embodiments of the present application, the volume distribution particle size Dv1 of the first negative electrode active material is 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, or 8.0 μm, and the volume distribution particle size Dv1 of the second negative electrode active material is 3.5 μm, 3.8 μm, 4 μm, 4.5 μm, 6 μm, 8 μm, or 10.0 μm.

[0106] Furthermore, in some embodiments of the present application, the volume distributed particle size Dv50 of the first negative electrode active material is larger than the volume distributed particle size Dv50 of the second negative electrode active material.

[0107] Furthermore, in some embodiments of the present application, the volume distribution particle size Dv50 of the first negative electrode active material is 10 μm to 20 μm, and optionally 15 μm to 16.5 μm.

[0108] Furthermore, in some embodiments of the present application, the volume distribution particle size Dv50 of the second negative electrode active material is 10 μm to 20 μm, and optionally 13 μm to 14.5 μm.

[0109] Further, exemplarily, in some embodiments of the present application, the D of the first negative electrode active material V 50 is 13.0 μm, 13.5 μm, 14.0 μm, 14.5 μm, 15.0 μm, 15.5 μm, 16.0 μm, 16.5 μm, 17.0 μm, or a range between any two of the aforementioned values.

[0110] Further, exemplarily, in some embodiments of the present application, the D of the second negative electrode active material V 50 is 13.0 μm, 13.2 μm, 13.4 μm, 13.5 μm, 14.0 μm, 14.5 μm, or a range between any two of the aforementioned numbers.

[0111] Furthermore, in some embodiments of the present application, the particle size distribution (D V 90-D V 10) / D V 50 is the particle size distribution (D V 90-D V 10) / D VGreater than 50.

[0112] Furthermore, in some embodiments of the present application, the particle size distribution (D V 90-D V 10) / D V 50 is ≦2.0, and optionally 1.2 to 1.8.

[0113] Furthermore, in some embodiments of the present application, the particle size distribution (D V 90-D V 10) / D V 50 is ≦1.8, and optionally 1.0 to 1.6.

[0114] In the above technical proposal, the first and second negative electrode active materials (D V 90-D V 10) / D V By setting 50 within the above range, a good normal particle size distribution can be formed, which is advantageous for improving the energy density of the lithium ion battery and at the same time, is advantageous for improving the fast charging performance of the lithium ion battery.

[0115] Illustratively, in some embodiments of the present application, the first negative electrode active material (D V 90-D V 10) / D V 50 is 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or 1.8.

[0116] of the second negative electrode active material (D V 90-D V 10) / D V 50 is 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 or a range between any two of the aforementioned numbers.

[0117] Furthermore, in some embodiments of the present application, the specific surface area of ​​the first negative electrode active material is smaller than the specific surface area of ​​the second negative electrode active material.

[0118] Furthermore, in some embodiments of the present application, the specific surface area of ​​the first negative electrode active material is 0.5 m 2 / g~3.0m 2 / g, and selectively 1.0m 2 / g~2.5m 2 / g.

[0119] Furthermore, in some embodiments of the present application, the specific surface area of ​​the second negative electrode active material is 2.5 m 2 / g~4.4m 2 / g, and selectively 3.0m 2 / g~4.0m 2 / g.

[0120] Illustratively, in some embodiments of the present application, the specific surface area of ​​the first negative electrode active material is 0.5 m 2 / g, 1m 2 / g, 1.5m 2 / g, 2m 2 / g, 2.5m 2 / g or 3.0m 2 The specific surface area of ​​the second negative electrode active material is 2.5 m 2 / g, 2.8m 2 / g, 3m 2 / g, 3.5m 2 / g, 4m 2 / g or 4.4m 2 / g.

[0121] Furthermore, in the above technical solution, the specific surface area of ​​the first or second negative electrode active material is the specific surface area of ​​the material measured when CO2 is used as a carrier gas. Because CO2 molecules are relatively small and can enter the micropore structure of the material, the CO2 adsorption specific surface area can reflect information such as the percentage of micropores in the material. When the CO2 adsorption specific surface area of ​​the first negative electrode active material is within the above range, it can effectively improve the energy density of the lithium-ion battery and simultaneously improve the fast charging performance of the lithium-ion battery.

[0122] Furthermore, in some embodiments of the present application, the first negative electrode active material is (1) D of the first negative electrode active materialV 10 is 5 μm to 9 μm, and optionally 5.8 μm to 7.8 μm; (2) D of the first negative electrode active material V 90≦30 μm, and optionally 20 μm to 30 μm; (3) D of the first negative electrode active material V 99≦40 μm, and optionally 30 μm to 40 μm; (4) The gram capacity of the first negative electrode active material is 355 mAh / g to 365 mAh / g, and optionally 357 mAh / g to 363 mAh / g.

[0123] Furthermore, in some embodiments of the present application, the second negative electrode active material is (1) D of the second negative electrode active material V 10 is 6 μm to 10.0 μm, and optionally 7.5 μm to 9.0 μm; (2) D of the second negative electrode active material V 90≦30 μm, and optionally 20 μm to 30 μm; (3) D of the second negative electrode active material V 99≦40 μm, and optionally 30 μm to 40 μm; (4) The gram capacity of the second negative electrode active material is 352 mAh / g to 362 mAh / g, and optionally 354 mAh / g to 360 mAh / g; (5) At least a portion of the surface of the second negative electrode active material has a carbon coating layer.

[0124] Furthermore, in the above technical solution, since the gram capacity of the first or second negative electrode active material is within the above range, the battery can effectively achieve both a relatively high energy density and good fast charging performance.

[0125] Furthermore, in the above technical solution, since the initial coulombic efficiency of the first or second negative electrode active material is within the above range, the energy density of the lithium ion battery can be effectively improved, and at the same time, it is advantageous to improve the fast charging performance of the lithium ion battery.

[0126] In the above technical proposal, the D of the first or second negative electrode active material V 10. D V 50, D V 90, D V 99, D V Setting 1 within the above range is advantageous for improving the energy density of the lithium ion battery, and at the same time, is advantageous for improving the rapid charging performance of the lithium ion battery.

[0127] Furthermore, in some embodiments of the present application, the first negative electrode active material and / or the second negative electrode active material are both artificial graphite.

[0128] Furthermore, in some embodiments of the present application, the packed density of the negative electrode membrane layer is 1.25 g / cm 3 or more, and optionally 1.28 g / cm 3 ~1.65g / cm 3 is.

[0129] Illustratively, in some embodiments of the present application, the compacted density of the negative electrode membrane layer is 1.28 g / cm 3 , 1.3g / cm 3 , 1.35g / cm 3 , 1.4g / cm 3 , 1.45g / cm 3 , 1.5g / cm 3 , 1.55g / cm 3 , 1.6g / cm 3 or 1.65 g / cm 3 is.

[0130] Furthermore, in some embodiments of the present application, the coating weight per unit area of ​​the negative electrode film layer is 0.075 mg / mm 2 or more, and selectively 0.08 mg / mm 2 ~0.11mg / mm 2 is.

[0131] Illustratively, in some embodiments of the present application, the coating weight per unit area of ​​the negative electrode film layer is 0.08 mg / mm 2, 0.09 mg / mm 2 , 0.1 mg / mm 2 or 0.11 mg / mm 2 is.

[0132] In some embodiments, the negative electrode film layer optionally further includes a conductive agent, which may be at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0133] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, which may be at least one selected from 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).

[0134] In some embodiments, the negative electrode membrane layer optionally further comprises other additives, such as a thickener (eg, sodium carboxymethylcellulose (CMC-Na)).

[0135] When the conductive agent, adhesive and other auxiliary agents are present, the present application does not particularly limit the types and amounts thereof, and those skilled in the art can select and determine them according to actual needs.

[0136] In some embodiments, the negative electrode current collector may employ 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 base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0137] In some embodiments, the negative electrode plate may be manufactured in the following manner: The components for manufacturing the negative electrode plate, such as the negative electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then applied onto a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0138] The negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode film layer is disposed on one or both of the two facing surfaces of the negative electrode current collector. It should be noted that the parameters of each negative electrode film layer given in this application refer to the parameters of the negative electrode film layer on one side of the negative electrode current collector. When the negative electrode film layer is disposed on both sides of the negative electrode current collector, if the parameters of the negative electrode film layer on either side satisfy the present application, it is considered to fall within the protection scope of the present application.

[0139] In the present application, the negative electrode plate may further include other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode plate further includes a conductive undercoating (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In some embodiments, the negative electrode plate further includes a protective layer covering the surface of the negative electrode film layer.

[0140] In the present application, the ID / IG value of a material (e.g., a first negative electrode active material, a second negative electrode active material, etc.) can be tested using a Raman spectrometer, and the ID is 1350±50 cm -1 represents the D peak intensity of the Raman spectrum of the material at 1,580 ± 50 cm -1 This represents the G peak intensity of the Raman spectrum of the material at 100°C. The test conditions can be as follows: excitation wavelength 532 nm, grating with 600 lines, objective lens 50x, integration time 10 s, number of integrations 3, scan the surface, obtain D peak and G peak intensities at 100 points, calculate ID / IG for 100 points, remove the maximum and minimum 25 ID / IG, and average the remaining 50 points to obtain the ID / IG of the material. The test equipment can be a Horiba LabRAM HR800 Raman spectrometer.

[0141] In this application, the powder compaction density of the negative electrode active material has a meaning known in the art and can be tested using methods known in the art. For example, referring to GB / T 24533-2009, it can be tested using an electronic pressure tester (e.g., UTM7305): a certain amount M of powder sample to be tested is placed in a compaction mold (bottom area S), a different pressure is set (49000 N can be used in this application), the pressure is held for 30 seconds, the pressure is removed, and the device is allowed to wait 10 seconds. The thickness H of the powder compacted at this pressure is then read and calculated to obtain the compaction density at this pressure. The compaction density of the negative electrode active material at this pressure is = M / (H*S).

[0142] In the present application, the graphitization degree of a material (e.g., a first negative electrode active material, a second negative electrode active material) has a meaning known in the art and may be measured using equipment and methods known in the art. For example, the graphitization degree can be measured using an X-ray diffractometer (e.g., a Bruker D8 Discover). The test is performed in accordance with JIS K 0131-1996 and JB / T 4220-2011 to obtain the average interlayer spacing d002 of the C(002) crystal plane in the material's crystal structure. The graphitization degree can then be calculated using the formula g = (0.344 - d002) / (0.344 - 0.3354) × 100%. In the above formula, d002 is the average interlayer spacing of the C(002) crystal plane in the material's crystal structure, expressed in nanometers (nm).

[0143] In this application, the OI of a material (e.g., a first negative electrode active material, a second negative electrode active material) has the meaning known in the art, and may be measured using equipment and methods known in the art. Based on the General Rules for X-ray Diffraction Analysis and the Method for Measuring the Lattice Parameter of Graphite (JIS K 0131-1996 and JB / T4220-2011), an X-ray diffraction spectrum can be obtained using an X-ray powder diffractometer (X'pert PRO), and the orientation index of the negative electrode material can be calculated based on the formula OI = C004 / C110, where C004 is the peak area of ​​the characteristic 004 diffraction peak, and C110 is the peak area of ​​the characteristic 110 diffraction peak.

[0144] In this application, the tap density of a material (e.g., the first negative electrode active material, the second negative electrode active material) has the meaning known in the art and may be measured using equipment and methods known in the art. For example, it can be measured using a powder tap density tester in accordance with GB / T 5162-2006. The test equipment used is the Dandong Baite BT-301, and the test parameters are a vibration frequency of 250±15 times / min, an amplitude of 3±0.2 mm, a vibration count of 5000 times, and a 25 mL measuring cylinder.

[0145] In this application, the volume distribution particle sizes Dv1, Dv10, Dv50, and Dv90 of a material (e.g., a first negative electrode active material, a second negative electrode active material, etc.) have the meanings known in the art, representing the particle sizes corresponding to the cumulative volume distribution percentages of the material reaching 1%, 10%, 50%, and 90%, respectively, and can be measured using equipment and methods known in the art. For example, they may be measured using a laser particle size analyzer in accordance with GB / T 19077-2016. The testing equipment may be a Mastersizer 3000 laser particle size analyzer manufactured by Malvern Instruments, UK.

[0146] In this application, the specific surface area of ​​a material (e.g., a first negative electrode active material, a second negative electrode active material) has a meaning known in the art and may be measured using equipment and methods known in the art. For example, it may be tested using the nitrogen gas adsorption specific surface area analysis test method in accordance with GB / T 19587-2017 and calculated using the Brunauer Emmett Teller (BET) method. The test equipment may be a Tri-Star 3020 specific surface area pore size analyzer manufactured by Micromeritics, Inc., USA.

[0147] In the present application, whether or not a coating layer is present on the surface of a material (for example, the first negative electrode active material, the second negative electrode active material, etc.) can be determined using a transmission electron microscope.

[0148] In this application, the gram capacity of a material (e.g., a first negative electrode active material, a second negative electrode active material) has a meaning known in the art and may be tested using a method known in the art. An exemplary test method is as follows: a sample powder, a conductive agent carbon black (Super P), and an adhesive polyvinylidene fluoride (PVDF) are uniformly mixed with a solvent N-methylpyrrolidone (NMP) in a mass ratio of 91.6:1.8:6.6 to prepare a slurry, which is then applied to the surface of a negative electrode current collector copper foil and dried in an oven for use; ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent; LiPF6 is then dissolved in the organic solvent to a concentration of 1 mol / L; L of electrolyte was prepared. Next, a CR2430 button cell was assembled with the electrolyte in an argon-protected glove box using a lithium metal sheet as the counter electrode and polyethylene (PE) film as the separator. The resulting button cell was then allowed to stand for 12 hours, after which it was discharged at 0.05 C to 0.005 V at 25 °C, allowed to stand for 10 minutes, and then discharged again at 50 μA to 0.005 V. The discharge capacity was then recorded. The ratio of discharge capacity to sample mass is the gram capacity of the corresponding material (e.g., first negative electrode active material, second negative electrode active material, etc.).

[0149] The thickness of the negative electrode film layer has a meaning known in the art and can be tested using methods known in the art, such as a micrometer (e.g., Mitutoyo 293-100 type, 0.1 μm accuracy). The thickness ranges provided in this application are the thickness ranges of the negative electrode film layer on one side of the negative electrode current collector. If the thickness of the negative electrode film layer on either side of the negative electrode current collector is within the ranges provided in this application, the application is satisfied.

[0150] It should be noted that the above-mentioned various parameter tests on the negative electrode active material or the negative electrode film layer can be performed by sampling and testing from a secondary battery manufactured according to the following steps.

[0151] The secondary battery is discharged (for safety reasons, the secondary battery is generally fully discharged), the negative electrode plate is removed from the secondary battery, and the negative electrode plate is immersed in dimethyl carbonate for a certain period of time (e.g., 2 to 10 hours). The negative electrode plate is then removed and dried at a certain temperature for a certain period of time (e.g., 60°C for 4 hours or more). After drying, the negative electrode plate is removed. At this point, various parameters related to the negative electrode film layer, such as the compaction density, OI value, and thickness of the negative electrode film layer, can be sampled and tested from the dried negative electrode plate.

[0152] The dried negative electrode plate is baked at a certain temperature for a certain time (for example, 400°C for 2 hours or more), and the negative electrode active material is sampled from any region of the baked negative electrode plate (the powder may be scraped off using a blade for sampling), and the collected negative electrode active material is sieved (for example, sieved through a 200-mesh sieve) to finally obtain a sample that can be used to test each of the above-mentioned negative electrode active material parameters.

[0153] In the present application, the above-mentioned first and second negative electrode active materials are commercially available or can be prepared by the following methods of the present application.

[0154] In some embodiments, the first negative electrode active material can be made according to the following method.

[0155] 1) Select petroleum-based needle coke raw material, crush it, shape it and classify it, 2) Heat treatment: 1) The process material and adhesive after the process are mixed in a ratio of (8-12):1 to carry out granulation treatment, the granulation treatment is heated to 600-700 ° C and kept at a constant temperature for 8-12 hours, and then cooled for 5-10 hours to obtain intermediate product 1; 3) Graphitization: The intermediate product 1 of 2) is subjected to graphitization treatment, and the graphitization temperature is 2800 to 3200°C.

[0156] The granulation treatment in step 2) is carried out by increasing the temperature to 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, or a range between any two of the aforementioned values, and then maintaining the temperature constant. The mass ratio in step 2) is selected from 8:1, 9:1, 10:1, 11:1, 12:1, or a range between any two of the aforementioned values.

[0157] The graphitization temperature in step 3) above is 2800°C, 2900°C, 3000°C, 3100°C, 3200°C, or a range between any two of the aforementioned values.

[0158] In some embodiments, the second negative electrode active material can be prepared according to the following method.

[0159] 1) Select petroleum-based needle coke raw material, crush it, shape it and classify it, 2) Heat treatment: 1) The process material and adhesive after the process are mixed in a mass ratio of (5-10): 1 to carry out granulation treatment, and the granulation treatment is heated to 600-700 ° C and kept at a constant temperature for 8-12 hours, and then cooled for 5-10 hours to obtain intermediate product 1; 3) Graphitization: The intermediate product 1 of 2) is subjected to graphitization treatment at a graphitization temperature of 3000 to 3400° C., and an intermediate product 2 is obtained.

[0160] 4) Fusion coating and carbonization: The intermediate product 2 from 3) is subjected to a coating process, using a coating agent such as an organic carbon source to carry out solid-liquid fusion. The amount of coating agent added is 1 to 10% of the total mass of the intermediate product 2. This is followed by carbonization, with the carbonization temperature being 1000 to 1200°C. The granulation process in step 2) is performed by heating the mixture to 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, or a temperature range between any two of the above, and then maintaining the temperature constant. The mass ratio in step 2) is selected from 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or a temperature range between any two of the above.

[0161] The graphitization temperature in step 3) above is 3000°C, 3100°C, 3200°C, 3300°C, 3400°C, or a range between any two of the aforementioned values.

[0162] The organic carbon source in step 4) may include one or more of coal pitch, petroleum pitch, phenolic resin, coconut shell, etc. The amount of coating agent added in step 4) is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the total mass of the intermediate product 2, or a range between any two of the aforementioned values. The carbonization temperature in step 4) may be selected from 1000°C, 1010°C, 1050°C, 1100°C, 1150°C, 1180°C, 1200°C, or a range between any two of the aforementioned values.

[0163] [Positive electrode plate] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.

[0164] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two facing surfaces of the positive electrode current collector.

[0165] 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 base layer and a metal layer formed on at least one surface of the polymer 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, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0166] In some embodiments, when the battery cell is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for use in lithium-ion batteries. For example, the positive electrode active material may include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (can be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (can be abbreviated as LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (can be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (can be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which can be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0167] In some embodiments, when the battery cell is a lithium-ion battery, the positive electrode active material may be any positive electrode active material known in the art for use in lithium-ion batteries, such as, for example, a sodium transition metal oxide, a polyanion-type compound, or a Prussian blue-based compound.

[0168] Since the battery undergoes desorption and depletion of Li during the charge and discharge process, the molar content of Li will be different when the battery is discharged to different states. In the list of positive electrode materials in the examples of this application, the molar content of Li is the initial state of the material, i.e., the state before being introduced. When the positive electrode material is used in a battery system and undergoes charge and discharge cycles, the molar content of Li may change.

[0169] In the list of positive electrode materials in the examples of this application, the molar content of O is only a theoretical value, and since lattice oxygen release causes a change in the molar content of oxygen, in reality, the molar content of O fluctuates.

[0170] In some embodiments, the positive electrode membrane layer optionally further includes an adhesive, which may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0171] In some embodiments, the positive electrode film layer optionally further includes a conductive agent, for example, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0172] In some embodiments, the positive electrode plate may be manufactured in the following manner: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then applied to a positive electrode current collector, and the positive electrode plate can be obtained after processes such as drying and cold pressing.

[0173] [Electrolytes] The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and it may be selected according to need. For example, the electrolyte may be liquid, gel, or all-solid.

[0174] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0175] In some embodiments, the electrolyte salt can be at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0176] In some embodiments, the solvent may be selected from 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.

[0177] In some embodiments, the electrolyte solution optionally further contains 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 battery performance, such as an additive that improves battery overcharge performance, or an additive that improves battery high-temperature or low-temperature performance.

[0178] [Separator] In some embodiments, the battery cell further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with excellent chemical and mechanical stability can be selected and used.

[0179] In some embodiments, the separator may be made of at least one material selected from 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 the layers may be the same or different, and are not particularly limited.

[0180] In some embodiments, the positive and negative electrodes and the separator can be fabricated into an electrode assembly by a winding or lamination process.

[0181] In some embodiments, the battery cell may include an outer casing, which may be used to package the electrode assembly and electrolyte.

[0182] In some embodiments, the battery cell exterior can be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The battery cell exterior can be a pouch, such as a bag-like pouch. The pouch can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0183] The present application does not particularly limit the shape of the battery cell, and it may be cylindrical, rectangular, or any other shape. For example, Figure 4 shows an example of a battery cell 5 with a rectangular structure.

[0184] In some embodiments, referring to FIG. 5 , the exterior body 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, which together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the top cover assembly 53 may cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and this can be selected by those skilled in the art according to specific actual needs.

[0185] In some embodiments, the battery cells may be assembled into a battery module, and the number of battery cells included in the battery module may be one or more, the specific number being selectable by those skilled in the art depending on the application and capacity of the battery module.

[0186] Fig. 6 shows an example of a battery module 4. Referring to Fig. 6, in the battery module 4, a plurality of battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of battery cells 5 may be fixed by fasteners.

[0187] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of battery cells 5 are accommodated in this accommodating space.

[0188] In some embodiments, the battery modules may be assembled into a battery pack, which may include one or more battery modules, the specific number of which may be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0189] 7 and 8 show an example of a battery pack 1. Referring to FIGS. 7 and 8, 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, and the upper housing 2 may be provided with a lid on the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0190] A second aspect of the present application further provides a power consuming device including a secondary battery according to the present application. The secondary battery may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may include, but is 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, satellites, energy storage systems, etc.

[0191] The power consumption device can be selected as a battery cell, a battery module or a battery pack based on its usage needs.

[0192] 9 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of the secondary battery of the power consuming device, a battery pack or battery module can be employed.

[0193] Another example of the device may be a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and may employ a battery cell as a power source.

[0194] Example The following examples of the present application are described. The examples described below are illustrative and are used only to interpret the present application, and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If the manufacturer of the reagents or equipment used is not specified, they are all common commercially available products.

[0195] The materials used in the examples and comparative examples of the present application can be commercially available or can be produced by the following process.

[0196] [Production of Material 1-1] (First negative electrode active material): 1) Select petroleum-based needle coke raw material, crush it, shape it and classify it, 2) Heat treatment: 1) The process material and adhesive after the process are mixed in a mass ratio of 10:1 to carry out granulation, and the granulation process is heated to 650 ° C and kept constant for 10 hours, and then cooled for another 8 hours to obtain intermediate product 1. 3) Graphitization: The intermediate product 1 of 2) is subjected to graphitization treatment, and the graphitization temperature is 3000°C.

[0197] Here, the negative electrode active material 1-1 has a median value R1 of the Raman value ID / IG 50is 0.08, and the powder compaction density at 49000N is 1.95g / cm 3 The graphitization degree is 94.5%, the powder OI is 4.8, and the volume distribution particle size D V 50 is 15 μm, and the volume distribution particle size D V 1 is 3.1 μm and the specific surface area is 2.0 m 2 / g.

[0198] [Production of Materials 1-2 and 1-3] The difference from the manufacturing method of Material 1-1 is the graphitization temperature, the details of which are shown in Table 1.

[0199] [Table 1]

[0200] [Production of Material 2-1] (Second Negative Electrode Active Material): 1) Select petroleum-based needle coke raw material, crush it, shape it and classify it, 2) Heat treatment: 1) The process material and adhesive after the process are mixed in a mass ratio of 8:1 to perform granulation, and the granulation process is heated to 650 ° C and kept at a constant temperature for 10 hours, and then cooled for another 8 hours to obtain intermediate product 1. 3) Graphitization: Intermediate product 1 of 2) was subjected to graphitization treatment at a graphitization temperature of 3200°C, and intermediate product 2 was obtained. 4) Fusion coating and carbonization: The intermediate product 2 in 3) was subjected to a coating process, and a liquid-phase phenolic resin coating agent was used for solid-liquid fusion. The amount of coating agent added was 5% of the total mass of the intermediate product 2. Subsequently, a carbonization process was performed, and the carbonization temperature was 1150°C, thereby obtaining a negative electrode active material 2-1.

[0201] Here, the negative electrode active material 2-1 has a median value R1 of the Raman value ID / IG 50 is 0.25, and the powder compaction density at 49000N is 1.81g / cm 3 The graphitization degree is 93.5%, the powder OI is 3.3, and the volume distribution particle size D V 50 is 14.5 μm, and the volume distribution particle size D V1 is 6.8 μm and the specific surface area is 3.4 m 2 / g.

[0202] [Production of Materials 2-2, 2-3, and 2-4]: The manufacturing method is similar to that of Material 2-1, but the difference is the amount of coating agent added or the carbonization temperature, as shown in Table 2.

[0203] [Table 2]

[0204] Example 1 Secondary battery manufacturing: 1. Manufacturing of negative electrode plates A first negative electrode active material (material 1-1), a conductive agent carbon black (Super P), a thickener sodium carboxymethyl cellulose, and an adhesive styrene butadiene rubber were mixed in a weight ratio of 96.4:1:1.2:1.4 in an appropriate amount of solvent deionized water with sufficient stirring to form a first negative electrode slurry.

[0205] A second negative electrode active material (material 2-1), a conductive agent carbon black (Super P), a thickener sodium carboxymethyl cellulose, and an adhesive styrene butadiene rubber were mixed in a weight ratio of 96.4:1:1.2:1.4 in an appropriate amount of solvent deionized water with sufficient stirring to form a second negative electrode slurry.

[0206] The first negative electrode slurry was applied to the surface of a negative electrode current collector copper foil to form a lower region of the negative electrode film layer, and the second negative electrode slurry was applied to the first negative electrode film layer to form an upper region of the negative electrode film layer. After drying, cold pressing, and other processes, a negative electrode plate was obtained. Here, the mass ratio of the first negative electrode slurry to the second negative electrode slurry was 6:4, and the compaction density of the negative electrode film layer was 1.6 g / cm. 3 The coating weight of the negative electrode film layer on one side is 8.6 mg / cm 2 is.

[0207] 2. Manufacturing of positive electrode plates Cathode active material NCM622 (LiNi 0.6 Co 0.2 Mn 0.2 O2), conductive agent (Super P), adhesive polyvinylidene fluoride (PVDF), etc. were mixed in a mass ratio of 96:2:2, and the solvent N-methylpyrrolidone (NMP) was added and thoroughly stirred to obtain a positive electrode slurry. The positive electrode slurry was then uniformly applied to a positive electrode current collector aluminum foil to form a positive electrode film layer, and after processes such as drying and cold pressing, a positive electrode plate was obtained.

[0208] 3. Electrolyte production Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and then thoroughly dried lithium salt LiPF6 was dissolved in the mixed organic solvent at a ratio of 1 mol / L to prepare an electrolyte solution. Fluoroethylene carbonate (FEC) was then added. The content of FEC was 1 wt% of the total mass of the electrolyte solution.

[0209] 4. Separator Polypropylene film is selected.

[0210] 5. Secondary battery manufacturing: The positive electrode plate, separator, and negative electrode plate are stacked in this order, with the separator positioned between the positive and negative electrodes to act as an insulator, and then wound to obtain an electrode assembly. The electrode assembly is placed in an outer casing, and the prepared electrolyte is injected into the dried electrode assembly. A secondary battery is obtained through processes such as vacuum packaging, standing, chemical formation, and shaping.

[0211] Examples 2 and 3 The battery manufacturing methods of Examples 2 and 3 were similar to Example 1, except that different first negative electrode active materials, Materials 1-2 and 1-3, were selected, as shown in Table 3.

[0212] Examples 4 to 6 The battery manufacturing methods of Examples 4 to 6 were similar to Example 1, but the difference was that different second negative electrode active materials were selected: Materials 2-2, 2-3, and 2-4, as shown in Table 3.

[0213] Comparative Example 1 A secondary battery was assembled in the same manner as in Example 1, except that material 2-1 was selected as the first negative electrode active material and material 1-1 was selected as the second negative electrode active material, as shown in Table 3.

[0214] Comparative Example 2 The negative electrode active material (material 1-1 and material 2-1 mixed in a mass ratio of 6:4), conductive agent carbon black (Super P), thickener sodium carboxymethyl cellulose, and adhesive styrene butadiene rubber were mixed in a weight ratio of 96.4:1:1.2:1.4 in an appropriate amount of solvent deionized water with sufficient stirring to form a negative electrode slurry. The negative electrode slurry was applied to the surface of a negative electrode current collector copper foil to form a negative electrode film layer, which was then dried, cold pressed, and other processes to obtain a negative electrode plate. Here, the compaction density of the negative electrode film layer was 1.6 g / cm. 3 The coating weight of the negative electrode film layer on one side is 8.6 mg / cm 2 is.

[0215] Comparative Example 3 A secondary battery was assembled in the same manner as in the manufacturing method of Comparative Example 2, except that the negative electrode active material contained only material 1-1.

[0216] Comparative Example 4 A secondary battery was assembled in the same manner as in the manufacturing method of Comparative Example 2, except that the negative electrode active material contained only material 2-1.

[0217] [Performance test method] Each performance parameter in all examples and comparative examples is measured according to the following method.

[0218] (1) Raman median R of the negative electrode active material in the negative electrode film layer 50 . The Raman spectrum of each carbon material may be obtained using a laser confocal Raman spectrometer, with a laser wavelength of 532 nm. During testing, an appropriate amount of sample is taken and its surface is scanned in all directions, with a scanning area of ​​100 μm × 100 μm, a step size of 2 μm, and a total of 2500 scanning points. Raman spectra are obtained at different positions, and corresponding Raman values ​​ID / IG are obtained. The testing equipment may be a high-precision Renishaw laser confocal Raman spectrometer. The Raman values ​​ID / IG obtained from the 2500 scanned points are sorted in ascending order and labeled 1#, 2#, 3#, ..., 2500#, respectively. The Raman value ID / IG corresponding to the 50% ranking of the scanning points (corresponding to 1250#) is defined as R50, also referred to as the median Raman value ID / IG. In this application, the median Raman value ID / IG of the first negative electrode active material is defined as R1. 50 The median of the Raman values ​​ID / IG of the second negative electrode active material is expressed as R2 50 (2) The gram volume of the material.

[0219] The negative electrode active material, conductive agent Super P, and adhesive (PVDF) were uniformly mixed with the solvent NMP (N-methylpyrrolidone) in a mass ratio of 91.6:1.8:6.6 to prepare a slurry. The slurry was then applied to a copper foil current collector to prepare a negative electrode film layer, which was then dried in an oven and cold-pressed for use. The compaction density of the negative electrode film layer was 1.3 g / cm. 3A lithium metal sheet was used as the counter electrode, a polyethylene (PE) film as the separator, and ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1. LiPF6 was then uniformly dissolved in the solution to obtain an electrolyte solution with a LiPF6 concentration of 1 mol / L. The above components were assembled into a CR2430 button cell in an argon-protected glove box. After allowing the resulting button cell to stand for 12 hours, it was discharged at a constant current of 0.05 C to 0.005 V, allowed to stand for 10 minutes, and then discharged at a constant current of 50 μA to 0.005 V. It was then allowed to stand for 10 minutes, and then discharged at a constant current of 10 μA to 0.005 V. The sum of the three discharge capacities represents the gram capacity of the material.

[0220] (3) Powder compaction density test The powder compaction density of the negative electrode active material has a meaning known in the art and can be tested using a method known in the art. For example, referring to GB / T 24533-2009, it can be tested using an electronic pressure tester (e.g., UTM7305): a certain amount M of powder sample to be tested is placed in a special compaction mold (bottom area S), a different pressure is set (49000 N can be used in this application), the pressure is maintained for 30 seconds, the pressure is removed, and the device is allowed to read the thickness H of the powder after compaction at this pressure, and the compaction density at this pressure can be calculated, where the compaction density of the negative electrode active material at this pressure = M / (H*S).

[0221] (4) Thickness H of the single-sided negative electrode film layer. The thickness H of the single-sided negative electrode film layer can be measured using a micrometer. The thickness of the negative electrode film layer described in this application refers to the thickness of the negative electrode film layer for assembling a battery after being consolidated by cold pressing.

[0222] (5) Degree of orientation of negative electrode active material OI. In accordance with the general principles of X-ray diffraction analysis and the lattice parameter measurement methods for graphite JIS K 0131-1996 and JB / T4220-2011, an X-ray diffraction spectrum was obtained using an X-ray powder diffractometer (X'pert PRO), and the orientation index of the negative electrode material was calculated based on OI=C004 / C110, where C004 is the peak area of ​​the characteristic diffraction peak of 004, and C110 is the peak area of ​​the characteristic diffraction peak of 110.

[0223] (6) Mass energy density of battery At 25°C, the battery cell was charged at a constant current of 0.33C to 4.4V, then charged at a constant voltage until the current reached 0.05C. After leaving the battery cell standing for 5 minutes, the battery cell was discharged at a constant current of 0.33C to 2.8V to obtain the discharge capacity D0.

[0224] Mass energy density = D0 / mass of secondary battery (mass energy density unit: Wh / kg) In the formula, D0 is the measured discharge capacity of the battery core

[0225] (7) Battery rate performance test. At 25°C, the secondary battery is charged at a constant current of 0.33C to 4.4V, then charged at a constant voltage until the current reaches 0.05C. After leaving the battery standing for 5 minutes, the secondary battery is discharged at a constant current of 0.33C to 2.8V, and the actual capacity is recorded as C0.

[0226] Next, the secondary battery was charged at a constant current of 0.5C0, 1.3C0, 2.0C0, 2.8C0, 3.5C0, 4.5C0, and 6.0C0 in order to a negative electrode cutoff potential of 4.4V or 0V (based on the first one reached). After each charge, it was necessary to discharge it to 2.8V at 1C0, and discharge it at different charge rates of 10%, 20%, 30%, ..., 80% SOC (State of Charge). The negative electrode potential corresponding to charging up to 0 V (charge, state of charge) was recorded, and charge rate-negative electrode potential curves at different SOC states were plotted and linearly fitted to obtain the charge rates corresponding to 0 V at different SOC states. These charge rates, i.e., the charge windows at those SOC states, were denoted as C10% SOC, C20% SOC, C30% SOC, C40% SOC, C50% SOC, C60% SOC, C70% SOC, and C80% SOC, respectively. The charge time T (assuming no lithium deposition in the secondary battery) for the secondary battery from 10% SOC to 80% SOC was calculated using the formula (60 / C20% SOC + 60 / C30% SOC + 60 / C40% SOC + 60 / C50% SOC + 60 / C60% SOC + 60 / C70% SOC + 60 / C80% SOC) × 10%, and is expressed in minutes. The shorter this charging time, the better the rapid charging performance of the secondary battery.

[0227] The performance parameters of each of the examples and comparative examples are as shown in Table 3.

[0228] [Table 3]

[0229] The data in the table above reveals the following: Examples 1-6 meet the design of the present application, and the batteries can achieve both good fast charging performance and relatively high energy density.

[0230] As can be seen from Comparative Example 1, the R1 50 is R2 50 Since it is not within the scope of this application, fast charging performance will be affected.

[0231] As can be seen from Comparative Example 2, the negative electrode active material is a physical mixture of Material 1-1 and Material 2-1, and the Raman median values ​​of the negative electrode active materials in the lower and upper regions tend to match, which is not consistent with the design of the present application and also affects the fast charging performance.

[0232] As can be seen from Comparative Examples 3 and 4, when the negative electrode active material contains only material 1-1 or material 2-1, the battery cannot achieve both good rapid charging performance and relatively high energy density.

[0233] The above-mentioned embodiments are only some of the embodiments of the present application, but not all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of protection of the present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative effort fall within the scope of protection of the present application. [Explanation of symbols]

[0234] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 battery cell, 51 case, 52 electrode assembly, 53 top cover assembly, 10 negative electrode plate, 101 negative electrode current collector, 102 negative electrode film layer, 102a second surface, 102b first surface, 1021 lower region, 1022 upper region, 1023 middle region, 200 first carbon-based material, 201 outer region, 202 inner region.

Claims

1. A secondary battery includes a negative electrode plate, the negative electrode plate including a negative electrode current collector and a negative electrode film layer formed on at least one surface of the negative electrode current collector, the negative electrode film layer including a lower region and an upper region, the lower region including a first negative electrode active material, and the upper region including a second negative electrode active material, and a median value of Raman values ​​I D / I G of the first negative electrode active material is R1 ５０ and the median of the Raman values ​​ID / IG of the second negative electrode active material is R2 ５０ When the above R1 ５０ is the above R2 ５０ and the degree of graphitization of the first negative electrode active material is greater than the degree of graphitization of the second negative electrode active material.

2. The R1 ５０ is between 0.05 and 0.15, and / or The R2 ５０ 2. The secondary battery according to claim 1, wherein the value of the ρ is 0.20 to 0.

40.

3. The R1 ５０ is between 0.05 and 0.1, and / or The R2 ５０ 3. The secondary battery according to claim 1, wherein the value of the ρ is 0.25 to 0.

35.

4. The degree of graphitization of the first negative electrode active material is ≧92%, and / or 4. The secondary battery according to claim 1, wherein the degree of graphitization of the second negative electrode active material is 91% or more.

5. The graphitization degree of the first negative electrode active material is 93% to 95%, and / or 5. The secondary battery according to claim 1, wherein the second negative electrode active material has a degree of graphitization of 92% to 94%.

6. 6. The secondary battery according to claim 1, wherein the powder compaction density of the first negative electrode active material is greater than the powder compaction density of the second negative electrode active material.

7. The first negative electrode active material has a powder compaction density of ≥ 1.95 g / cm when tested at a pressure of 49000 N. ３ and / or The second negative electrode active material has a powder compaction density of 1.81 g / cm when tested at a pressure of 49,000 N. ３ ~1.87 g / cm ３ 7. The secondary battery according to claim 1, wherein:

8. The first negative electrode active material has a powder compaction density of 1.96 g / cm when tested at a pressure of 49,000 N. ３ ~1.99 g / cm ３ and / or The second negative electrode active material has a powder compaction density of 1.82 g / cm when tested at a pressure of 49,000 N. ３ ~1.86 g / cm ３ 8. The secondary battery according to claim 1, wherein

9. 9. The secondary battery according to claim 1, wherein the powder OI of the first negative electrode active material is larger than the powder OI of the second negative electrode active material.

10. The powder OI of the first negative electrode active material is 2.0 to 10.0, and / or 10. The secondary battery according to claim 1, wherein the powder OI of the second negative electrode active material is 1.0 to 8.

0.

11. The powder OI of the first negative electrode active material is 4.0 to 8.0, and / or 11. The secondary battery according to claim 1, wherein the powder OI of the second negative electrode active material is 2.5 to 5.

5.

12. 12. The secondary battery according to claim 1, wherein the tap density of the first negative electrode active material is smaller than the tap density of the second negative electrode active material.

13. The tap density of the first negative electrode active material is ≧0.8 g / cm ３ and / or The specific surface area of ​​the second negative electrode active material is 3.0 m ２ / g to 4.3m ２ 13. The secondary battery according to claim 1, wherein the ionic strength is 0.1 / g.

14. The tap density of the first negative electrode active material is 0.85 g / cm ３ ~1.15g / cm ３ and / or The specific surface area of ​​the second negative electrode active material is 3.2 m ２ / g to 4.1m ２ 14. The secondary battery according to claim 1, wherein the ionic strength is 0.1 / g.

15. 15. The secondary battery according to claim 1, wherein the volume distribution particle size Dv1 of the first negative electrode active material is smaller than the volume distribution particle size Dv1 of the second negative electrode active material.

16. The volume distribution particle size Dv1 of the first negative electrode active material is 1.0 μm to 8.0 μm, and / or 16. The secondary battery according to claim 1, wherein the second negative electrode active material has a volume distribution particle size Dv1 of 3.5 μm to 10.0 μm.

17. The volume distribution particle size Dv1 of the first negative electrode active material is 3.0 μm to 5.0 μm, and / or 17. The secondary battery according to claim 1, wherein the second negative electrode active material has a volume distribution particle size Dv1 of 5.5 μm to 8.0 μm.

18. 18. The secondary battery according to claim 1, wherein the first negative electrode active material has a volume distribution particle size Dv50 larger than the volume distribution particle size Dv50 of the second negative electrode active material.

19. The first negative electrode active material has a volume distribution particle size Dv50 of 10 μm to 20 μm, and / or 19. The secondary battery according to claim 1, wherein the second negative electrode active material has a volume distribution particle size Dv50 of 10 μm to 20 μm.

20. The first negative electrode active material has a volume distribution particle size Dv50 of 14 μm to 16.5 μm, and / or 20. The secondary battery according to claim 1, wherein the second negative electrode active material has a volume distribution particle size Dv50 of 13 μm to 15.5 μm.

21. The particle size distribution (D Ｖ 90-D Ｖ 10) / D Ｖ 50 is the particle size distribution (D Ｖ 90-D Ｖ 10) / D Ｖ 21. The secondary battery according to claim 1, wherein the resistance is greater than 50.

22. The particle size distribution (D Ｖ 90-D Ｖ 10) / D Ｖ 50 is ≦2.0, and / or The particle size distribution (D Ｖ 90-D Ｖ 10) / D Ｖ 22. The secondary battery according to claim 1, wherein 50 is ≦1.

8.

23. The particle size distribution (D Ｖ 90-D Ｖ 10) / D Ｖ 50 is 1.2 to 1.8, and / or The particle size distribution (D Ｖ 90-D Ｖ 10) / D Ｖ 23. The secondary battery according to claim 1, wherein 50 is 1.0 to 1.

6.

24. 24. The secondary battery according to claim 1, wherein the specific surface area of ​​the first negative electrode active material is smaller than the specific surface area of ​​the second negative electrode active material.

25. The specific surface area of ​​the first negative electrode active material is 0.5 m ２ / g to 3.0m ２ / g, and / or The specific surface area of ​​the second negative electrode active material is 2.5 m ２ / g to 4.4m ２ 25. The secondary battery according to claim 1, wherein the SiO2 content is 1 / g.

26. The specific surface area of ​​the first negative electrode active material is 1.0 m ２ / g to 2.5m ２ / g, and / or The specific surface area of ​​the second negative electrode active material is 3.0 m ２ / g to 4.0m ２ 26. The secondary battery according to claim 1, wherein the SiO2 content is 1 / g.

27. The first negative electrode active material is (1) D of the first negative electrode active material Ｖ 10 is 5 μm to 9 μm; (2) D of the first negative electrode active material Ｖ 90≦30 μm; (3) D of the first negative electrode active material Ｖ 99≦40 μm; (4) The secondary battery according to any one of claims 1 to 26, characterized in that the gram capacity of the first negative electrode active material is 355 mAh / g to 365 mAh / g.

28. The first negative electrode active material is (1) D of the first negative electrode active material Ｖ 10 is 5.8 μm to 7.8 μm; (2) D of the first negative electrode active material Ｖ 90 is 20 μm to 30 μm; (3) D of the first negative electrode active material Ｖ 99 is 30 μm to 40 μm; (4) The secondary battery according to any one of claims 1 to 27, characterized in that the gram capacity of the first negative electrode active material is 357 mAh / g to 363 mAh / g.

29. The second negative electrode active material is (1) D of the second negative electrode active material Ｖ 10 is 6 μm to 10.0 μm; (2) D of the second negative electrode active material Ｖ 90≦30 μm; (3) D of the second negative electrode active material Ｖ 99≦40 μm; (4) The second negative electrode active material has a gram capacity of 352 mAh / g to 362 mAh / g; (5) The secondary battery according to any one of claims 1 to 28, wherein at least one of the following characteristics is satisfied: (1) a surface of at least a portion of the second negative electrode active material has a carbon coating layer;

30. The second negative electrode active material is (1) D of the second negative electrode active material Ｖ 10 is 7.5 μm to 9.0 μm; (2) D of the second negative electrode active material Ｖ 90 is 20 μm to 30 μm; (3) D of the second negative electrode active material Ｖ 99 is 30 μm to 40 μm; (4) The gram capacity of the second negative electrode active material is 354 mAh / g to 360 mAh / g; (5) The secondary battery according to any one of claims 1 to 29, wherein at least one of the following characteristics is satisfied: (1) a surface of at least a portion of the second negative electrode active material has a carbon coating layer;

31. 31. The secondary battery according to claim 1, wherein the first negative electrode active material and / or the second negative electrode active material is / are both artificial graphite.

32. The compaction density of the negative electrode film layer is 1.25 g / cm ３ or more; and / or The coating weight per unit area of ​​the negative electrode film layer is 0.075 mg / mm ２ 32. The secondary battery according to claim 1, wherein:

33. The compaction density of the negative electrode film layer is 1.28 g / cm ３ ~1.65g / cm ３ and / or The coating weight per unit area of ​​the negative electrode film layer is 0.08 mg / mm ２ ~0.11mg / mm ２ 33. The secondary battery according to claim 1, wherein

34. A power consuming device comprising the secondary battery of any one of claims 1 to 33.

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