Negative electrode material and preparation method and application thereof

Abstract

The invention provides a negative electrode material and a preparation method and application thereof, the negative electrode material comprises an inner core and a carbon coating layer arranged on the surface of the inner core, and a / (b * c) is more than 0 and less than or equal to 1; a = Id / Ig, Id is the strength at 1580 cm <-1 > in a Raman spectrum of the negative electrode material, and Ig is the strength at 1360 cm <-1 > in the Raman spectrum of the negative electrode material; b = Dn (0.15) / Dn (1), Dn (0.15) is the number of scanning points with Id / Ig < = 0.15 in the confocal Raman spectrum of the negative electrode material, and Dn (1) is the number of scanning points with Id / Ig < = 1 in the confocal Raman spectrum of the negative electrode material; c is equal to C004 / C110, C004 is the area of a 004 diffraction peak in an XRD (X-Ray Diffraction) spectrum of the negative electrode material, C110 is the area of a 110 diffraction peak in the XRD spectrum of the negative electrode material, and the fast charging performance and the low-temperature performance of the negative electrode material are improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to negative electrode materials and their preparation methods and applications. Background Art

[0002] Currently, graphite anode materials, due to their layered structure, suffer from slow ion diffusion and poor low-temperature charge and discharge capabilities, limiting their application in power batteries. While it's possible to improve the ion transport capacity and fast-charging performance by adjusting the particle size and structure of the anode material, this can lead to decreased low-temperature performance and increased production costs. Therefore, a negative electrode material with both excellent fast-charging and low-temperature charge and discharge performance is needed. Summary of the Invention

[0003] In view of this, the present application provides a negative electrode material, a preparation method and an application thereof. The negative electrode material has a carbon coating layer with good coating uniformity, which improves the ion transmission rate of the negative electrode material and is beneficial to improving the fast charging performance and low-temperature charging and discharging performance of the negative electrode material.

[0004] In a first aspect, the present application provides a negative electrode material, comprising a core and a carbon coating layer disposed on the surface of the core, wherein the negative electrode material satisfies: 0<a / (b×c)≤1;

[0005] Wherein, a=Id / Ig, and Id is the Raman spectrum of the negative electrode material at 1580cm -1 The intensity at 1360 cm in the Raman spectrum of the negative electrode material is -1 The strength of the place;

[0006] b=Dn(0.15) / Dn(1), wherein Dn(0.15) is the number of scanning points with Id / Ig≤0.15 in the confocal Raman spectrum of the negative electrode material, and Dn(1) is the number of scanning points with Id / Ig≤1 in the confocal Raman spectrum of the negative electrode material;

[0007] c=C 004 / C 110 , the C 004 is the area of the 004 diffraction peak in the XRD pattern of the negative electrode material, and the C 110 The area of the 110 diffraction peak in the XRD pattern of the negative electrode material.

[0008] Optionally, a is 0.05-0.5; b is 0.01-1; and c is 5-50.

[0009] Optionally, the negative electrode material satisfies: 0≤d / 100e≤3; wherein d=D50 particle size of the negative electrode material-D50 particle size of the inner core; and e represents the residual carbon value of the carbon coating layer.

[0010] Optionally, the e is less than or equal to 5%.

[0011] The negative electrode material provided in the present application has a good coating layer with good coating uniformity, which can improve the ionic conductivity of the negative electrode material and is beneficial to improving the fast charging capability and low-temperature charging and discharging capability of the negative electrode material.

[0012] Optionally, the present application provides a method for preparing a negative electrode material, comprising the following steps: mixing a core material and a coating layer raw material, and obtaining the negative electrode material after reaction.

[0013] Optionally, the reaction includes a first stage, a second stage and a third stage.

[0014] Optionally, the temperature of the first stage is 200°C-450°C, the temperature of the second stage is 500°C-700°C, and the temperature of the third stage is 800°C-1300°C.

[0015] Optionally, the core material includes at least one of graphitized particles, natural graphite, flake graphite, hard carbon and soft carbon.

[0016] Optionally, the raw material of the coating layer includes at least one of petroleum asphalt, coal asphalt, ethylene tar, coal tar, emulsified asphalt and resin.

[0017] The preparation method of the negative electrode material provided in the present application has a simple preparation process, and the prepared negative electrode material has good fast charging performance and good low-temperature charging and discharging capabilities.

[0018] In a second aspect, the present application provides a negative electrode plate, which includes a negative electrode current collector and a negative electrode active material layer arranged on the surface of the negative electrode current collector, and the negative electrode active material layer includes the negative electrode material described in the first aspect.

[0019] The negative electrode sheet provided in this application has excellent electrochemical performance and high specific capacity.

[0020] In a third aspect, the present application provides a battery, which includes a positive electrode plate and the negative electrode plate described in the second aspect. The battery provided by the present application has good low-temperature performance, good fast charging performance, and excellent charging and discharging performance.

[0021] In a fourth aspect, the present application provides an electrical device, which includes the battery described in the third aspect.

[0022] The electrical equipment provided in this application has high safety performance for low-temperature use, long service life, and strong product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Figure 1 A schematic diagram of the cross-sectional structure of a negative electrode material provided in one embodiment of the present application;

[0025] Figure 2 A schematic diagram of the cross-sectional structure of a negative electrode sheet provided in one embodiment of the present application;

[0026] Figure 3 This is the confocal Raman spectrum provided in Example 1 of the present application. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] See also Figure 1 , is a schematic diagram of the cross-sectional structure of the negative electrode material provided in one embodiment of the present application. The negative electrode material 100 includes a core 10 and a carbon coating layer 11 disposed on the surface of the core 10. The negative electrode material 100 satisfies the following conditions: 0<a / (b×c)≤1; wherein a=Id / Ig, Id is the 1580cm in the Raman spectrum of the negative electrode material. -1 Ig is the intensity at 1360 cm in the Raman spectrum of the negative electrode material. -1 b = Dn(0.15) / Dn(1), Dn(0.15) is the number of scanning points with Id / Ig≤0.15 in the confocal Raman spectrum of the negative electrode material, and Dn(1) is the number of scanning points with Id / Ig≤1 in the confocal Raman spectrum of the negative electrode material; c = C 004 / C 110 , C 004 is the area of the 004 diffraction peak in the XRD pattern of the negative electrode material, C 110 The area of the 110 diffraction peak in the XRD pattern of the negative electrode material. By controlling the parameters a, b, and c to satisfy 0≤a / (b×c)≤1, the negative electrode material of this application can be provided with a surface coating layer, good coating uniformity, and high coating quality, thereby enabling the negative electrode material to obtain a high ion transport rate, good low-temperature performance, and fast charging performance. The negative electrode material provided in this application has good fast charging performance and low-temperature charge and discharge performance, which is beneficial for multi-scenario application of batteries.

[0029] In the present application, the negative electrode material satisfies 0<a / (b×c)≤1. Specifically, a / (b×c) can be, but is not limited to, 0, 0.2, 0.4, 0.6, 0.8, 0.9, or 1. In one embodiment of the present application, a / (b×c) can be 0-0.5. In another embodiment of the present application, a / (b×c) can be 0.5-1, which can further improve the fast charging performance and low-temperature charge and discharge performance of the negative electrode material.

[0030] In this application, a=Id / Ig, where Id is the Raman spectrum of the negative electrode material at 1580 cm -1 The intensity at represents the peak caused by defects in the negative electrode material, and Ig is the peak at 1360 cm in the Raman spectrum of the negative electrode material. -1 The ratio of the two can represent the disorder of the negative electrode material. The inner core of the negative electrode material has a low degree of disorder, and the carbon coating on the inner core surface increases the defects in the negative electrode material, thereby increasing the disorder of the negative electrode material a. A larger a indicates more defects caused by the carbon coating. A thicker carbon coating of the negative electrode material is beneficial to improving the fast charging performance of the negative electrode material.

[0031] In one embodiment of the present application, a is 0.05-0.5, and the negative electrode material has a carbon coating layer of a certain thickness, which can improve the conductivity and fast charging performance of the negative electrode material. Specifically, a can be, but is not limited to, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4 or 0.5. In one embodiment of the present application, a can be 0.1-0.3, which can further improve the fast charging performance of the negative electrode material. In another embodiment of the present application, a can be 0.3-0.5.

[0032] In the present application, b = Dn(0.15) / Dn(1), where Dn(0.15) is the number of scanning points with Id / Ig≤0.15 in the confocal Raman spectrum of the negative electrode material, and Dn(1) is the number of scanning points with Id / Ig≤1 in the confocal Raman spectrum of the negative electrode material, which can represent the coating uniformity of the negative electrode material. The confocal Raman testing method for the negative electrode material includes: using a scanning point-by-scanning method, using a laser of a certain wavelength to perform a single scanning point-by-scanning scan on the negative electrode material present in the range, with a scanning speed of 1 / second to 10 / second, and a scanning number of 300-2000 scanning points, obtaining the Raman distribution of each scanning point, and obtaining b after statistics. Dn(0.15) is the number of scanning points with Id / Ig≤0.15 divided by the number of all scanning points, and Dn(1) is the number of scanning points with Id / Ig≤1 in the confocal Raman spectrum of the negative electrode material, that is, the number of all scanning points. For the scanning points with Id / Ig≤0.15, the smaller the thickness of the carbon coating layer of the corresponding negative electrode material, the worse the coating effect, which has an adverse effect on the electrochemical properties of the negative electrode material. The smaller b is, the smaller the proportion of scanning points with poor coating effect in the confocal Raman spectrum, which indicates that the overall coating uniformity of the negative electrode material is better.

[0033] In one embodiment of the present application, b is 0.01-1. The smaller the b value, the better the coating uniformity of the negative electrode material, the higher the proportion of the negative electrode material containing the carbon coating layer, which is beneficial to improving the low-temperature electrochemical performance of the negative electrode material. Specifically, b can be, but is not limited to, 0.01, 0.1, 0.2, 0.4, 0.6, 0.8 or 1. In one embodiment of the present application, b can be 0.01-0.1, at which time the coating uniformity of the negative electrode material is good, which is beneficial to improving the low-temperature charge and discharge performance of the negative electrode material. In another embodiment of the present application, b can be 0.1-1.

[0034] In this application, c=C 004 / C 110 , where C 004 is the area of the 004 diffraction peak in the XRD pattern of the negative electrode material, C 110 The ratio c is the area of the 110 diffraction peak in the XRD pattern of the negative electrode material. The smaller the orientation degree of the negative electrode material, the higher the diffusion ability of the negative electrode material and the deeper the diffusion, which is conducive to improving the fast charging capability of the negative electrode material.

[0035] In one embodiment of the present application, c is 5-50. The smaller the c value, the lower the anisotropy of the negative electrode material, the higher the isotropy, the higher the tap density and ion diffusion degree of the negative electrode material, and the faster charging performance and cycle life of the negative electrode material are improved. Specifically, c can be, but is not limited to, 5, 10, 15, 20, 30, 40, 45 or 50. In one embodiment of the present application, c can be 10-30, at which time the negative electrode material has a high ion transmission number and good fast charging performance. In another embodiment of the present application, c can be 30-50.

[0036] In one embodiment of the present application, the negative electrode material satisfies 0≤d / 100e≤3, d=D50 particle size of the negative electrode material-D50 particle size of the inner core, and e represents the residual carbon value of the carbon coating layer. The negative electrode material controls the parameters d and e so that the thickness of the carbon coating layer is close to the residual carbon value of the carbon coating layer, and d / 100e is close to 1. At this time, the higher the linear correlation between d and e, the better the consistency of the negative electrode material, and the higher the coating uniformity of the negative electrode material. During the use of the battery, the resistance to ion diffusion is the same, the kinetic performance is the same, and the fast charging performance of the negative electrode material can be guaranteed. Specifically, d / 100e can be, but is not limited to, 0, 0.5, 0.8, 1, 1.2, 1.85, 2, 2.5 or 3, etc. In one embodiment of the present application, d / 100e can be 0.5-1. The closer d / 100e is to 1, the more consistent the thickness of the carbon coating layer of the negative electrode material and the residual carbon value of the carbon coating layer of the negative electrode material tend to be. The higher the coating uniformity of the negative electrode material, the better the fast charging performance.

[0037] In one embodiment of the present application, d = the D50 particle size of the negative electrode material minus the D50 particle size of the core, representing the average thickness of the carbon coating. This indicates whether the negative electrode material has a carbon coating on its surface and the thickness of the carbon coating. An appropriate thickness of the carbon coating on the surface of the negative electrode material and its strong bonding ability can prevent the carbon coating from falling off during charge and discharge, thereby improving the low-temperature performance and cycle stability of the negative electrode material. In some embodiments, d can be obtained through particle size analysis, and its absolute value is used in the calculation.

[0038] In one embodiment of the present application, e represents the residual carbon value of the carbon coating layer, and e is less than or equal to 5%. That is to say, e represents the mass proportion of the carbon coating layer in the negative electrode material. The larger e is, the higher the mass proportion of the carbon coating layer of the surface negative electrode material is, which is beneficial to improving the fast charging performance of the negative electrode material. Specifically, e may be, but is not limited to, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, or less than or equal to 1%, etc. In one embodiment of the present application, e may be less than or equal to 3%. In another embodiment of the present application, e may be 3%-4%. In some embodiments, e can be calculated by the ratio of the residual amount of the coating material after sintering to the amount of coating material added, and its absolute value is used in the calculation.

[0039] In one embodiment of the present application, by controlling the parameters a, b, c, d and e of the negative electrode material and satisfying 0<a / (b×c)≤1 and 0≤d / 100e≤3 at the same time, the surface of the negative electrode material has a carbon coating layer with an appropriate thickness of the carbon coating layer and good coating uniformity, and the compaction density, fast charging performance and low temperature performance of the negative electrode material are balanced. The negative electrode material has good fast charging performance and excellent low temperature charge and discharge performance, which is beneficial to improving the fast charging performance and low temperature cycle performance of the battery.

[0040] This application also provides a preparation method, comprising mixing a core material and a coating layer raw material, and reacting to obtain a negative electrode material. The preparation method provided herein is novel and simple, and can produce a negative electrode material with excellent fast-charging performance and low-temperature charge-discharge performance. This method can be used to produce the negative electrode material described in any of the above embodiments.

[0041] In one embodiment of the present application, the core material can promote core formation, thereby improving the capacity and conductivity of the negative electrode material. Specifically, the core material can include, but is not limited to, at least one of graphitized particles, natural graphite, flake graphite, hard carbon, and soft carbon. In one embodiment of the present application, the core material can be graphitized particles. In another embodiment of the present application, the core material can be hard carbon.

[0042] In one embodiment of the present application, the core material may be primary particles and / or secondary particles. Multiple primary particles agglomerate to form larger secondary particles. In another embodiment of the present application, the core material is graphitized secondary particles, which can further improve the specific capacity and fast-charging performance of the negative electrode material.

[0043] In one embodiment of the present application, the graphitized particles of the secondary particles can be obtained by mixing coke with a binder to form a mixture, and then heat-treating the mixture to obtain graphitized particles of the secondary particles. The coke is obtained by crushing and calcining chemical by-products such as petroleum coke, asphalt coke and coal tar, and the calcination temperature is less than or equal to 1500°C. Specifically, the calcination temperature may be, but is not limited to, less than or equal to 1500°C, less than or equal to 1400°C, less than or equal to 1300°C, less than or equal to 1200°C, less than or equal to 1100°C or less than or equal to 1000°C, etc. In one embodiment of the present application, the calcination temperature may be less than or equal to 1200°C. In another embodiment of the present application, the calcination temperature may be less than or equal to 1000°C.

[0044] In one embodiment of the present application, a binder can be used to bind multiple chemical byproducts after coarse crushing to form secondary particles. Specifically, the binder can be, but is not limited to, at least one of petroleum asphalt, coal tar, ethylene tar, coal tar, emulsified asphalt, and resin. In one embodiment of the present application, the binder can be petroleum asphalt. In another embodiment of the present application, the binder can be ethylene tar.

[0045] In one embodiment of the present application, the binder comprises 1% to 20% by weight of the mixture. An appropriate amount of binder can enhance the bonding strength of the core material, thereby improving the structural stability of the negative electrode material. Specifically, the binder comprises, but is not limited to, 1%, 2%, 5%, 10%, 12%, 14%, 15%, 18%, or 20% by weight of the mixture. In one embodiment of the present application, the binder comprises 1% to 12% by weight of the mixture. In another embodiment of the present application, the binder comprises 10% to 20% by weight of the mixture.

[0046] In one embodiment of the present application, after the mixture is formed, stirring is further performed at a frequency of less than or equal to 50 Hz, which facilitates uniform distribution of the binder and coke. Specifically, the stirring frequency may be, but is not limited to, less than or equal to 50 Hz, less than or equal to 45 Hz, less than or equal to 40 Hz, less than or equal to 35 Hz, less than or equal to 30 Hz, or less than or equal to 20 Hz. In one embodiment of the present application, the stirring frequency is less than or equal to 40 Hz.

[0047] In one embodiment of the present application, the heat treatment temperature is 300°C-700°C, which is beneficial for improving the bonding ability of the core material. Specifically, the heat treatment temperature may be, but is not limited to, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, or 700°C. In one embodiment of the present application, the heat treatment temperature may be 300°C-600°C. In another embodiment of the present application, the heat treatment temperature may be 500°C-700°C.

[0048] In one embodiment of the present application, the coating layer raw material can be molten at a relatively high temperature and uniformly coated on the surface of the core material, and then a carbon coating layer can be formed on the surface of the core material, which is beneficial for improving the fast charging performance of the negative electrode material. Specifically, the coating layer raw material can include, but is not limited to, at least one of petroleum asphalt, coal asphalt, ethylene tar, coal tar, emulsified asphalt, and resin. In one embodiment of the present application, the coating layer raw material can be coal asphalt.

[0049] In one embodiment of the present application, the viscosity of the coating layer raw material is 1Pa·s-100000Pa·s. The appropriate viscosity can improve the uniform coating of the coating layer raw material on the surface of the core material and improve the coverage rate of the carbon coating layer. Specifically, the viscosity of the coating layer raw material can be, but is not limited to, 1Pa·s, 100Pa·s, 1000Pa·s, 2000Pa·s, 5000Pa·s, 8000Pa·s, 10000Pa·s, 50000Pa·s or 100000Pa·s, etc. In one embodiment of the present application, the viscosity of the coating layer raw material can be 1Pa·s-10000Pa·s. In another embodiment of the present application, the viscosity of the coating layer raw material can be 5000Pa·s-100000Pa·s.

[0050] In one embodiment of the present application, a core material and a coating layer raw material are mixed to form a mixed material. In the mixed material, the mass percentage of the coating layer raw material is 3%-25%. An appropriate amount of the coating layer raw material can evenly coat the surface of the core material, thereby increasing the coverage. Specifically, in the mixed material, the mass percentage of the coating layer raw material can be, but is not limited to, 3%, 5%, 10%, 13%, 18%, 20%, 23%, or 25%, etc. In one embodiment of the present application, the mass percentage of the coating layer raw material in the mixed material can be 3%-15%. In another embodiment of the present application, the mass percentage of the coating layer raw material in the mixed material can be 10%-25%.

[0051] In one embodiment of the present application, the reaction includes a first stage, a second stage and a third stage. The temperature of the first stage is 200°C-450°C, the temperature of the second stage is 500°C-700°C, and the temperature of the third stage is 800°C-1300°C. The first stage promotes the liquefaction of the coating layer raw material so that the coating layer raw material is coated on the surface of the core material. The second stage promotes the solidification of the coating layer raw material coated on the surface of the core material and volatilizes to form a carbon coating layer. The third stage makes the carbon coating layer disordered and improves the conductivity of the carbon coating layer.

[0052] In one embodiment of the present application, the temperature of the first stage is 200°C-450°C, which is conducive to promoting uniform coating of the coating layer raw materials. Specifically, the temperature of the first stage may be, but is not limited to, 200°C, 250°C, 300°C, 350°C, 400°C or 450°C. In one embodiment of the present application, the temperature of the first stage may be 200°C-350°C. In another embodiment of the present application, the temperature of the first stage may be 300°C-450°C. In some embodiments, during the first stage, the mixed materials are continuously mixed and stirred, and the mixing and stirring frequency is less than or equal to 50 Hz to prevent adhesion of the coating layer raw materials and promote dispersion of the coating layer raw materials.

[0053] In one embodiment of the present application, the duration of the first stage is 90 minutes to 180 minutes. An appropriate duration of the first stage can promote uniform mixing of the coating layer raw material and the core material, improve the liquefaction and dispersion effect of the coating layer raw material, and facilitate the preparation of the negative electrode material. Specifically, the duration of the first stage can be, but is not limited to, 90 minutes, 100 minutes, 120 minutes, 150 minutes, 160 minutes, or 180 minutes. In one embodiment of the present application, the duration of the first stage can be 90 minutes to 140 minutes. In another embodiment of the present application, the duration of the first stage can be 140 minutes to 180 minutes.

[0054] In one embodiment of the present application, before the first stage, the mixed material is also mixed and stirred, and the mixing time is 1h-3h, and the mixing frequency is less than or equal to 50Hz, which is conducive to improving the uniform distribution of the core material and the coating layer raw material. Specifically, the mixing time can be but not limited to 1h, 1.5h, 2h, 2.5h, 2.8h or 3h, etc.; the mixing frequency can be but not limited to less than or equal to 50Hz, less than or equal to 45Hz, less than or equal to 40Hz, less than or equal to 35Hz, less than or equal to 30Hz or less than or equal to 20Hz, etc. In one embodiment of the present application, the mixing time can be 1h-2.5h, and the mixing frequency is less than or equal to 40Hz. In some embodiments, the coating material and the core material can be mixed at high temperature, and high temperature is conducive to promoting the coating material to be converted into a liquid state, so that the coating material is better coated on the surface of the core material, which is conducive to the uniform coating of the subsequent coating layer.

[0055] In one embodiment of the present application, the temperature of the second stage is 500°C-700°C, which is conducive to the formation of the carbon coating layer. Specifically, the temperature of the second stage can be, but is not limited to, 500°C, 550°C, 600°C, 650°C or 700°C. In one embodiment of the present application, the temperature of the second stage can be 500°C-620°C. In another embodiment of the present application, the temperature of the second stage can be 580°C-700°C. In some embodiments, during the second stage, the mixed materials are continuously mixed and stirred, and the mixing and stirring frequency is less than or equal to 50Hz to prevent the coating layer raw materials from sticking, which is conducive to the formation of the carbon coating layer.

[0056] In one embodiment of the present application, the duration of the second stage is 60 minutes to 120 minutes. An appropriate second stage duration can improve the curing effect of the coating material. Specifically, the duration of the second stage can be, but is not limited to, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, or 120 minutes. In one embodiment of the present application, the duration of the second stage can be 60 minutes to 100 minutes. In another embodiment of the present application, the duration of the second stage can be 100 minutes to 120 minutes.

[0057] In one embodiment of the present application, the temperature of the third stage is 800°C-1300°C to increase the degree of disordering of the carbon coating layer. Specifically, the temperature of the third stage may be, but is not limited to, 800°C, 900°C, 1000°C, 1100°C, 1200°C, or 1300°C. In one embodiment of the present application, the temperature of the third stage may be 800°C-1100°C. In another embodiment of the present application, the temperature of the third stage may be 900°C-1300°C.

[0058] In one embodiment of the present application, the time of the third stage is 12h-16h. The appropriate time of the third stage can promote the disorder of the coating material, improve the conductivity of the coating layer, and enhance the electrochemical performance of the negative electrode material. Specifically, the time of the third stage can be, but is not limited to, 12h, 14h, 15h or 16h, etc. In one embodiment of the present application, the time of the third stage can be 12h-14.5h. In another embodiment of the present application, the time of the third stage can be 14.5h-16h. In some embodiments, during the third stage, the mixed materials are continuously mixed and stirred, and the frequency of the mixing and stirring is less than or equal to 50Hz, which is conducive to the formation of the negative electrode material.

[0059] See also Figure 2 , is a schematic diagram of the cross-sectional structure of the negative electrode sheet provided in this application. The negative electrode sheet 200 includes a negative electrode current collector 20 and a negative electrode active material layer 21 disposed on the surface of the negative electrode current collector 20. The negative electrode active material layer 21 includes the negative electrode material described in any of the above embodiments. The negative electrode sheet provided in this application has excellent fast charging performance, good low-temperature performance, and high cycling stability.

[0060] In one embodiment of the present application, the negative electrode current collector may include, but is not limited to, at least one of copper, aluminum, nickel, and stainless steel. In one embodiment of the present application, the negative electrode current collector may be copper foil.

[0061] In one embodiment of the present application, the negative electrode active material layer further includes a negative electrode conductive agent. The negative electrode conductive agent can increase the conductivity of the negative electrode material and improve electronic conductivity. Specifically, the negative electrode conductive agent may include, but is not limited to, at least one of graphite, carbon black, acetylene black, and graphene. In one embodiment of the present application, the negative electrode conductive agent may be graphite. In another embodiment of the present application, the negative electrode conductive agent may be carbon black.

[0062] In one embodiment of the present application, the negative electrode active material layer further includes a negative electrode binder. The negative electrode binder can improve the binding capacity of the components in the negative electrode active material layer and improve the binding capacity between the negative electrode active material layer and the current collector. Specifically, the negative electrode binder can be, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polybutadiene, acrylic resin, epoxy resin, polyethylene oxide, sodium carboxymethyl cellulose, and styrene-butadiene latex. In one embodiment of the present application, the negative electrode binder can be polyvinylidene fluoride. In another embodiment of the present application, the negative electrode binder can be sodium carboxymethyl cellulose.

[0063] The present application also provides a battery comprising a positive electrode and a negative electrode provided by any of the above embodiments. The negative electrode has a long cycle life and good fast charging performance, so the battery provided by the present application has excellent charge and discharge performance, good low temperature performance, and a long service life.

[0064] In one embodiment of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0065] In one embodiment of the present application, the positive electrode current collector may be, but is not limited to, at least one of copper, aluminum, nickel, and stainless steel. In one embodiment of the present application, the positive electrode current collector may be aluminum foil.

[0066] In one embodiment of the present application, the positive electrode active material can improve the conductivity, capacity, and cycle stability of the positive electrode sheet. Specific positive electrode active materials may include, but are not limited to, at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium manganese oxide, nickel cobalt manganese oxide, and nickel cobalt aluminum. In one embodiment of the present application, the positive electrode active material may be lithium cobalt oxide.

[0067] In one embodiment of the present application, the positive electrode active material layer further includes a positive electrode conductive agent. The positive electrode conductive agent can increase the electrical conductivity between the active materials and improve electronic conductivity. Specifically, the positive electrode conductive agent may include, but is not limited to, at least one of graphite, carbon black, acetylene black, and graphene. In one embodiment of the present application, the positive electrode conductive agent may be graphite. In another embodiment of the present application, the positive electrode conductive agent may be carbon black.

[0068] In one embodiment of the present application, the positive electrode active material layer further includes a positive electrode binder. The positive electrode binder can improve the binding ability of the components in the positive electrode active material layer and improve the binding ability between the positive electrode active material layer and the positive electrode current collector. Specifically, the positive electrode binder can be, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polybutadiene, acrylic resin, epoxy resin, polyethylene oxide, sodium carboxymethyl cellulose, and styrene-butadiene latex. In one embodiment of the present application, the positive electrode binder can be polyvinylidene fluoride.

[0069] In one embodiment of the present application, the battery further comprises a separator disposed between the positive electrode sheet and the negative electrode sheet. Specifically, the separator may be, but is not limited to, a woven membrane, a non-woven fabric, a microporous membrane, a composite membrane, a rolled membrane, or separator paper. In one embodiment of the present application, the battery further comprises an electrolyte. At least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet are immersed in the electrolyte. The electrolyte in the present application is not particularly limited and may be, but is not limited to, any substance known in the art as a battery electrolyte.

[0070] The present application also provides an electric device, which includes a battery provided by any of the above embodiments. The electric device provided by the present application has excellent comprehensive performance and strong market competitiveness. The electric device of the present application may refer to a vehicle, an electronic device, an energy storage system, etc. In one embodiment of the present application, the battery can be used in a vehicle to increase the charging speed of the vehicle's electricity. In another embodiment of the present application, the battery can also be used in an electronic device to increase the cycle stability of the electronic device battery and improve the battery's low-temperature performance.

[0071] The effects of the technical solution of this application are further illustrated below through specific examples.

[0072] Example 1

[0073] The core material (graphitized particles) with a D50 particle size of 12 μm and the coating layer raw material (petroleum asphalt) were mixed and stirred at a frequency of 30 Hz, in the first stage (maintained at 400 ° C for 2 hours), heated to the second stage (maintained at 600 ° C for 1.5 hours), and then heated to the third stage (maintained at 1100 ° C for 14 hours) to obtain a negative electrode material with a D50 particle size of 14 μm, wherein the mass ratio of the core material to the coating layer raw material is 95:5.

[0074] Example 2

[0075] The difference from Example 1 is that the first stage is not included.

[0076] Example 3

[0077] The difference from Example 1 is that the second stage is not included.

[0078] Example 4

[0079] The difference from Example 1 is that the third stage is not included.

[0080] Example 5

[0081] The difference from Example 1 is that the mass ratio of the core material to the coating layer raw material is 90:10.

[0082] Example 6

[0083] The difference from Example 1 is that the mass ratio of the core material to the coating layer raw material is 98:2.

[0084] Example 7

[0085] The difference from Example 1 is that the core material and the coating layer raw material are mixed at room temperature.

[0086] Example 8

[0087] The difference from Example 1 is that the D50 particle size of the core material is 15 μm.

[0088] Example 9

[0089] The difference from Example 1 is that the D50 particle size of the core material is 10 μm.

[0090] Example 10

[0091] The difference from Example 1 is that the mixing frequency is 50 Hz.

[0092] Example 11

[0093] The difference from Example 1 is that the mixing frequency is 15 Hz.

[0094] Example 12

[0095] The difference from Example 1 is that the coating layer material is resin.

[0096] Example 13

[0097] The difference from Example 1 is that the coating layer material is tar.

[0098] Example 14

[0099] The difference from Example 1 is that the mixing frequency is 50 Hz, the first stage is maintained for 90 minutes, and the second stage is maintained for 60 minutes.

[0100] Comparative Example 1

[0101] The difference from Example 1 is that the negative electrode material does not include a coating layer.

[0102] Comparative Example 2

[0103] The difference from Example 1 is that the core material includes incompletely graphitized particles.

[0104] Performance testing

[0105] The negative electrode materials prepared in Examples 1 to 14 and Comparative Examples 1 to 2 were subjected to Raman testing. The testing process was as follows: under an excitation light of 785 nm, the Raman spectrum of the negative electrode material was measured to obtain Id, which is the wavelength at 1580 cm in the Raman spectrum of the negative electrode material. -1 The intensity at 1360 cm in the Raman spectrum of the negative electrode material is obtained. -1 The ratio of the intensities at , is used to calculate the a value. The test results are shown in Table 1.

[0106] The negative electrode materials prepared in Examples 1-14 and Comparative Examples 1-2 were subjected to confocal Raman analysis. The confocal Raman spectrometer employed a point-by-point scanning method, using laser irradiation of a specific wavelength to scan particles within a specific range. The number of scans and the scan rate were adjustable, with a scan rate of 1 second per particle and a scan rate of 1200. The Id / Ig value of each scanned particle was obtained and summarized for analysis. The b-value was obtained, and the test results are shown in Table 1. Figure 3 This is the confocal Raman spectrum provided in Example 1 of the present application.

[0107] The negative electrode materials prepared in the above Examples 1 to 14 and Comparative Examples 1 to 2 were subjected to XRD (X-ray diffraction) testing to obtain the c value. The a, b, and c obtained in the test were calculated to obtain a / (b×c). The test results are shown in Table 1.

[0108] The negative electrode materials prepared in the above-mentioned Examples 1 to 14 and Comparative Examples 1 to 2 were subjected to particle size analysis tests to obtain d values. The test results are shown in Table 1.

[0109] The negative electrode materials prepared in Examples 1 to 14 and Comparative Examples 1 to 2 were designed according to the amount of binder added and the type of binder during the preparation process to obtain the e value. The d and e obtained in the test were calculated to obtain d / 100e. The test results are shown in Table 1.

[0110] The negative electrode materials prepared in Examples 1 to 14 and Comparative Examples 1 to 2 were assembled with positive electrode materials and electrolytes to prepare batteries, and the fast charging performance of the batteries was tested. The test process was as follows: the charge rate when lithium plating occurred was recorded at 25°C. The test results are shown in Table 2.

[0111] The negative electrode materials prepared in Examples 1 to 14 and Comparative Examples 1 to 2 were assembled with positive electrode materials and electrolytes to prepare batteries, and the low-temperature charge and discharge performance of the batteries was tested. The test process was as follows: charging at 1C at -25°C was performed, and the internal resistance of the batteries was recorded. The test results are shown in Table 2.

[0112] Table 1 Test results of various parameters

[0113] a b c a / (b×c) d e d / 100e Example 1 0.3 0.04 10.76 0.697 2.1 2％ 1.05 Example 2 0.3 0.08 9.1 0.412 2.4 1.5％ 1.33 Example 3 0.2 0.2 8.78 0.114 1.8 1.0％ 1.8 Example 4 0.25 0.05 10.78 0.569 1.5 1.5％ 1 Example 5 0.18 0.04 10.96 0.411 2.1 2％ 1.05 Example 6 0.28 0.04 11.82 0.592 2.0 2.4％ 0.83 Example 7 0.3 0.03 12.35 0.810 1.5 2.25％ 0.67 Example 8 0.24 0.04 18.53 0.324 1.8 2.4％ 0.75 Example 9 0.27 0.04 15.30 0.441 1.6 2.2％ 0.73 Example 10 0.32 0.04 9.80 0.816 1.7 2.4％ 0.708 Example 11 0.22 0.04 12.5 0.44 2.2 1.8％ 1.22 Example 12 0.23 0.04 18.5 0.311 2.1 2％ 1.05 Example 13 0.15 0.04 20.8 0.697 2.1 1.5％ 1.4 Example 14 0.26 0.05 16 0.325 3 1.0％ 3 Comparative Example 1 0.09 1 33.8 0.003 0 0 0 Comparative Example 2 0.85 0.05 15 1.133 1 2.5％ 0.4

[0114] Table 2 Electrochemical performance test results

[0115] Charging rate under lithium plating phenomenon Internal resistance at -25℃ (mΩ) Example 1 4C 390 Example 2 5C 513 Example 3 2C 499 Example 4 3C 330 Example 5 6C 310 Example 6 4C 400 Example 7 3C 455 Example 8 3.5C 435 Example 9 3C 420 Example 10 4C 460 Example 11 4C 398 Example 12 4.5C 370 Example 13 2.5C 485 Example 14 2.5C 520 Comparative Example 1 1C 600 Comparative Example 2 1.5C 470

[0116] According to Examples 1 to 14 and Comparative Examples 1 to 2, it can be seen that the negative electrode material provided by the present application has good fast charging performance and excellent low-temperature charge and discharge performance. According to Example 1 and Comparative Example 1, it can be seen that the a / (b×c) value of the negative electrode material provided by the present application is large, and at the same time, the d / 100e value is close to 1, which increases the charging rate of the negative electrode material when lithium precipitation occurs, reduces the low-temperature internal resistance of the battery, and improves the low-temperature charge and discharge performance of the negative electrode material; According to Example 1 and Comparative Example 2, it can be seen that the appropriate degree of graphitization of the core material can improve the coating uniformity and coating thickness of the coating layer, so that the a / (b×c) value is less than 1, which is beneficial to increase the charging rate of the negative electrode material when lithium precipitation occurs; According to Examples 1 and 2 to 3, the graphitization degree of the core material can improve the coating uniformity and coating thickness of the coating layer, so that the a / (b×c) value is less than 1, which is beneficial to increase the charging rate of the negative electrode material when lithium precipitation occurs; It can be seen from Example 4 that a suitable sintering method can improve the coating uniformity of the coating layer, and produce a negative electrode material with both fast charging performance and low-temperature charging and discharging performance; according to Examples 1 and 5-14, it can be seen that by changing the particle size of the core material, the material of the coating layer raw material, the ratio of the core material to the coating layer raw material, the mixing method of the core material and the coating layer raw material, and the mixing frequency, the values of a, b, c, d and e can be adjusted so that the negative electrode material satisfies 0<a / (b×c)≤1 and 0≤d / 100e≤3, thereby improving the fast charging performance and low-temperature performance of the negative electrode material.

[0117] The above is a preferred embodiment of the present application, but it should not be construed as limiting the scope of the present application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present application, and such improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A negative electrode material, characterized in that The negative electrode material comprises a core and a carbon coating layer disposed on the surface of the core, and the negative electrode material satisfies: 0<a / (b×c)≤1; Wherein, a=Id / Ig, and Id is the Raman spectrum of the negative electrode material at 1580cm -1 The intensity at 1360 cm in the Raman spectrum of the negative electrode material is -1 The strength of the place; b=Dn(0.15) / Dn(1), wherein Dn(0.15) is the number of scanning points with Id / Ig≤0.15 in the confocal Raman spectrum of the negative electrode material, and Dn(1) is the number of scanning points with Id / Ig≤1 in the confocal Raman spectrum of the negative electrode material; c=C 004 / C 110 , the C 004 is the area of the 004 diffraction peak in the XRD pattern of the negative electrode material, and the C 110 is the area of the 110 diffraction peak in the XRD pattern of the negative electrode material.

2. The negative electrode material according to claim 1, wherein The a is 0.05-0.5; the b is 0.01-1; and the c is 5-50.

3. The negative electrode material according to claim 1, wherein The negative electrode material satisfies the following conditions: 0≤d / 100e≤3; wherein d=D50 particle size of the negative electrode material minus D50 particle size of the inner core; and e represents the residual carbon value of the carbon coating layer.

4. The negative electrode material according to claim 3, wherein The e is less than or equal to 5%.

5. The negative electrode material according to any one of claims 1 to 4, characterized in that The method for preparing the negative electrode material comprises the following steps: The core material and the coating layer raw material are mixed and reacted to obtain the negative electrode material.

6. The negative electrode material according to claim 5, characterized in that The reaction includes a first stage, a second stage and a third stage; The temperature of the first stage is 200°C-450°C, the temperature of the second stage is 500°C-700°C, and the temperature of the third stage is 800°C-1300°C.

7. The negative electrode material according to claim 5, wherein The core material includes at least one of graphitized particles, natural graphite, flake graphite, hard carbon and soft carbon; the coating layer raw material includes at least one of petroleum asphalt, coal asphalt, ethylene tar, coal tar, emulsified asphalt and resin.

8. A negative electrode plate, characterized in that: The negative electrode plate includes a current collector and a negative electrode active material layer disposed on a surface of the negative electrode current collector, wherein the negative electrode active material layer includes the negative electrode material according to any one of claims 1 to 7.

9. A battery, characterized in that: The battery comprises a positive electrode sheet and the negative electrode sheet according to claim 8.

10. An electrical device, characterized in that: The electric device comprises the battery according to claim 9.

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