Electrode material and preparation method thereof, battery monomer, battery device and power utilization device

Abstract

The invention discloses an electrode material and a preparation method thereof, a battery monomer, a battery device and a power utilization device. The battery monomer comprises an electrode plate, the electrode plate comprises a current collector and an electrode film layer located on at least one side of the current collector, the electrode film layer comprises an electrode material, and the electrode material comprises an inner core comprising an electrode active material; the carbon coating material covers at least part of the surface of the inner core, a Raman spectrum of the carbon coating material has a G peak and a D peak, and ID / IG is smaller than or equal to 0.9. The electrode material provided by the invention can improve the storage life of the battery monomer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery technology, and in particular to an electrode material and a preparation method thereof, a battery monomer, a battery device, and a power utilization device. BACKGROUND

[0002] Battery monomers are widely used in electronic devices, such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric car toys, electric toy ships, electric toy planes, and electric tools.

[0003] In the development of battery monomers, how to improve the service life of battery monomers is one of the problems to be solved at present. SUMMARY

[0004] To solve the above technical problems, the present application provides an electrode material and a preparation method thereof, a battery monomer, a battery device, and a power utilization device.

[0005] In a first aspect, an embodiment of the present application provides a battery monomer, comprising an electrode sheet, the electrode sheet comprising a current collector and an electrode film layer located on at least one side of the current collector, the electrode film layer comprising an electrode material, the electrode material comprising: an inner core comprising an electrode active material; a carbon-coated material covering at least part of the surface of the inner core, the carbon-coated material having a Raman spectrum with a G peak and a D peak, and I D / I G less than or equal to 0.9.

[0006] By making the I D / I G of the coating layer less than or equal to 0.9, the coating layer has a higher degree of graphitization and a lower content of amorphous carbon, which can reduce the catalytic oxidation of the coating layer on the electrolyte, thereby reducing the interfacial reaction and the oxidative decomposition of the electrolyte, and further improving the service life of the battery monomer.

[0007] In some embodiments, the carbon-coated material forms a uniform coating layer on at least part of the surface of the inner core.

[0008] In some embodiments, the uniformity of the coating layer is characterized by a thickness value coefficient of variation, and the thickness value coefficient of variation of the coating layer is less than or equal to 8%.

[0009] In some embodiments, the thickness value coefficient of variation of the coating layer is 5% to 8%.

[0010] In some embodiments, the thickness of the coating layer is 2 nm to 5 nm.

[0011] In some embodiments, the molar fraction of unsaturated carbon atoms in the carbon-coated material relative to the total number of carbon atoms is greater than 50%.

[0012] In some embodiments, the carbon-coated material comprises one or more of carbon-containing compounds containing unsaturated bonds.

[0013] In some embodiments, the carbon-coated material comprises one or more of graphene, styrene-butadiene rubber, phenol-formaldehyde resin, fused-ring arenes and derivatives thereof, benzoic acid and derivatives thereof, naphthalene sulfonic acid and derivatives thereof, lignin, tannic acid.

[0014] In some embodiments, the electrode active material is a positive electrode active material.

[0015] In some embodiments, the positive electrode active material comprises one or more of layered lithium-containing transition metal oxides, lithium-containing phosphates, Prussian blue compounds, polyanion compounds, sodium transition metal oxides.

[0016] In some embodiments, the electrode material has a volume distribution particle size Dv50 of 0.5 μm to 15 μm.

[0017] In some embodiments, the electrode material has a specific surface area of 10 m 2 / g to 15 m 2 / g.

[0018] In some embodiments, the electrode material has a carbon content of 1.0% to 2.0%.

[0019] In some embodiments, the electrode active material is a negative electrode active material.

[0020] In some embodiments, the negative electrode active material comprises one or more of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, soft carbon, silicon, silicon-carbon composite materials.

[0021] In a second aspect, the embodiments of the present application provide a battery device comprising the battery cell of the first aspect of the present application.

[0022] In a third aspect, the embodiments of the present application provide a power consumption device comprising the battery device of the second aspect of the present application.

[0023] In a fourth aspect, the embodiments of the present application provide an electrode material, comprising: a core comprising an electrode active material; and a carbon-coated coating covering at least part of the surface of the core, wherein the Raman spectrum of the carbon-coated coating has a G peak and a D peak, and I D / I G is less than or equal to 0.9.

[0024] In some embodiments, the carbon-coated material forms a uniform coating layer on at least part of the surface of the core.

[0025] In some embodiments, the coating uniformity of the coating layer is characterized by a thickness value coefficient of variation, and the thickness value coefficient of variation of the coating layer is less than or equal to 8%.

[0026] In some embodiments, the thickness value coefficient of variation of the coating layer is 5% to 8%.

[0027] In some embodiments, the thickness of the coating layer is 2 nm to 5 nm.

[0028] In some embodiments, the raw material of the coating layer includes a carbon coating material, and the proportion of unsaturated carbon atoms in the carbon coating material relative to the total number of carbon atoms is greater than 50%.

[0029] In some embodiments, the carbon coating material includes one or more of carbon-containing compounds containing unsaturated bonds.

[0030] In some embodiments, the carbon coating material includes one or more of graphene, styrene-butadiene rubber, phenolic resin, condensed polycyclic aromatic hydrocarbon and its derivatives, benzoic acid and its derivatives, naphthalene sulfonic acid and its derivatives, lignin, tannic acid.

[0031] In a fifth aspect, the embodiments of the present application provide a preparation method of an electrode material, including the following steps:

[0032] Providing a core and a carbon source, respectively, wherein the proportion of unsaturated carbon atoms in the carbon source relative to the total number of carbon atoms is greater than or equal to 50%;

[0033] Coating the carbon source on at least part of the surface to obtain an electrode material.

[0034] In some embodiments, the mass ratio of the carbon source to the core is (0.5-2):10.

[0035] In some embodiments, the coating of the carbon source on at least part of the surface to obtain an electrode material includes:

[0036] Forming a pre-coating layer on at least part of the surface of the core with the carbon source to obtain a pre-coated material;

[0037] Performing sintering treatment on the pre-coated material to obtain an electrode material.

[0038] In some embodiments, the carbon source includes one or more of graphene, condensed polycyclic aromatic hydrocarbon and its derivatives, styrene-butadiene rubber, phenolic resin, benzoic acid and its derivatives, naphthalene sulfonic acid and its derivatives, lignin, tannic acid.

[0039] In some embodiments, the sintering treatment is performed at a temperature of 600°C to 800°C.

[0040] In some embodiments, the sintering process takes 8 to 12 hours.

[0041] In some embodiments, the heating rate of the sintering process is from 3°C / min to 8°C / min. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0043] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0044] Figure 2 An exploded schematic diagram of a battery device provided in some embodiments of this application.

[0045] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0046] Figure 4 The images show the Raman spectra of the electrode materials in some embodiments of this application.

[0047] Figure 5 These are transmission electron microscope (TEM) images of the electrode materials in some embodiments of this application.

[0048] Figure 6 Transmission electron microscope (TEM) images of electrode materials in some comparative examples of this application.

[0049] Figure 7 This is a schematic diagram of the sampling points for measuring the coating layer in an embodiment of this application.

[0050] The accompanying drawings are not necessarily drawn to scale.

[0051] The reference numerals in the attached drawings are explained as follows: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Reception space; 6. Battery module; 7. Battery cell. Detailed Implementation

[0052] Hereinafter, specific embodiments of the electrode material and the method for manufacturing the same, the battery cell, the battery device, and the electric device of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases of omitting detailed description of matters known to those skilled in the art, and repeated description of substantially identical configurations. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying 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 subject matter recited in the claims.

[0053] The ranges disclosed herein are defined by their lower and upper limits. Ranges can be defined by any upper and lower limits, whether or not they are explicitly disclosed. Ranges can be combined, i.e., any lower limit of a range or a value can be combined with any upper limit of another range or value. For example, if a range of 60-120 and a range of 80-110 are disclosed, it is understood that a range of 60-110 and a range of 80-120 are also disclosed. Furthermore, if a minimum range value of 1 and 2 are disclosed, and if a maximum range value of 3, 4, and 5 are disclosed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing each and every included number that is within the indicated range, wherein a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers within the range "0-5" are contemplated, and "0-5" is merely a shorthand way of describing each and every included number within the range. Additionally, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0055] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0056] If not otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method comprising step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0057] If not otherwise specified, the terms "first", "second", etc. in the present application are used to distinguish different objects, rather than to describe a specific sequence or primary and secondary relationship.

[0058] In the present application, the terms "a plurality of" and "a plurality of kinds" mean two or more.

[0059] In the description of the embodiments of the present application, if not otherwise specified, the first feature is "on" or "under" the second feature can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can mean that the first feature is directly above or obliquely above the second feature, or only means that the first feature is horizontally higher than the second feature. The first feature "under", "below" and "under" the second feature can mean that the first feature is directly below or obliquely below the second feature, or only means that the first feature is horizontally lower than the second feature.

[0060] Unless otherwise specified, the terms used in the present application have the commonly understood meanings understood by those skilled in the art.

[0061] Unless otherwise specified, the values of the parameters mentioned in the present application can be measured by various test methods commonly used in the art, for example, the test methods given in the examples of the present application. Unless otherwise specified, the test temperature of each parameter is 25°C.

[0062] The battery device mentioned in the embodiments of the present application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application can comprise a battery cell, a battery module or a battery pack, etc.

[0063] The battery cell is the smallest unit that constitutes a battery, which can realize the function of charging and discharging by itself. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in a mixed manner through a busbar component.

[0064] In some embodiments, the battery device may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0065] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0066] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0067] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0068] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices using battery devices.

[0069] Battery devices can be used as the power source for electrical devices or as energy storage units for electrical devices. Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0070] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0071] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0072] Figure 1 The diagram shows the structure of a vehicle provided in some embodiments of this application.

[0073] like Figure 1 As shown, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0074] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0075] In some embodiments, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0076] Figure 2 An exploded view of a battery is provided for some embodiments of the present application. As shown in Figure 2 , the battery device 2 includes a box 5 and battery cells (not shown), which are accommodated in the box 5.

[0077] The box 5 is used to accommodate the battery cells, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box part 5a and a second box part 5b, the first box part 5a and the second box part 5b are mutually coverable, and the first box part 5a and the second box part 5b together define an accommodation space 5c for accommodating the battery cells. The second box part 5b can be a hollow structure with one end open, and the first box part 5a is a plate-like structure, which is coverable on the open side of the second box part 5b to form the box 5 with the accommodation space 5c; or both the first box part 5a and the second box part 5b can be hollow structures with one side open, and the open side of the first box part 5a is coverable on the open side of the second box part 5b to form the box 5 with the accommodation space 5c. Of course, the first box part 5a and the second box part 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0078] To improve the sealing performance of the first box part 5a and the second box part 5b after being connected, a sealing member such as sealing glue, a sealing ring, etc. can be arranged between the first box part 5a and the second box part 5b.

[0079] Suppose the first box part 5a is coverable on the top of the second box part 5b, the first box part 5a can also be referred to as an upper box cover, and the second box part 5b can also be referred to as a lower box.

[0080] In the battery device 2, the battery cells can be one or multiple. If the battery cells are multiple, the multiple battery cells can be connected in series, in parallel or in a mixed manner, and the mixed manner means that there are both series connection and parallel connection among the multiple battery cells. The multiple battery cells can be directly connected in series, in parallel or in a mixed manner, and then the whole of the multiple battery cells is accommodated in the box 5; of course, the multiple battery cells can first be connected in series, in parallel or in a mixed manner to form a battery module 6, and then the multiple battery modules 6 are connected in series or in parallel or in a mixed manner to form a whole, which is accommodated in the box 5.

[0081] Figure 3 An exploded view of a battery module is provided for some embodiments of the present application. As shown in Figure 2 , the battery module 6 includes a box 5 and battery cells 7, which are accommodated in the box 5.

[0082] As shown in Figure 3 , in some embodiments, the battery cells 7 are multiple, and the multiple battery cells 7 are first connected in series, in parallel or in a mixed manner to form the battery module 6. The multiple battery modules 6 are then connected in series or in parallel or in a mixed manner to form a whole, which is accommodated in the box.

[0083] The plurality of battery cells 7 in the battery module 6 can be electrically connected through a busbar component to achieve parallel connection, series connection or mixed connection of the plurality of battery cells 7 in the battery module 6.

[0084] The battery cell mentioned in the embodiments of the present application can include a lithium ion battery cell or a sodium ion battery cell.

[0085] The battery cell includes an electrode assembly. The electrode assembly can be a roll structure or a stacked structure, and the embodiments of the present application are not limited thereto.

[0086] The electrode assembly generally includes electrode tabs and a separator film. The electrode tabs can include positive electrode tabs and negative electrode tabs.

[0087] The electrode tab includes a current collector and an electrode film layer on at least one side surface of the current collector. The electrode film layer includes an electrode material.

[0088] Carbon coating is a common method for surface treatment of electrode active materials. Forming a coating layer on the surface of the electrode active material can improve the conductivity of the active material, improve surface defects, and improve the wettability of the electrolyte. The current coating material is mainly amorphous carbon with a large surface area. The coating layer formed by amorphous carbon has strong catalytic effect, which reduces the oxidation potential of the electrolyte, accelerates the oxidation and decomposition of the electrolyte, and further leads to the deterioration of the battery life. In related technologies, in order to reduce the oxidation and decomposition of the electrolyte by the coating layer, glucose, sucrose, polyethylene glycol, etc. are generally used as carbon sources, the content of amorphous carbon in the coating layer is reduced by increasing the sintering temperature, or the interface is optimized by multi-layer coating to reduce the reactivity. However, due to the structural characteristics of the active material itself, the sintering temperature cannot be higher than 800 DEG C, which leads to a large amount of amorphous carbon in the coating layer obtained by sintering, and the activity of amorphous carbon cannot be effectively reduced, which has limited effect on reducing the oxidation and decomposition of the electrolyte. If the sintering temperature is increased to 800 DEG C or even higher in order to reduce the proportion of amorphous carbon in the coating layer, high temperature will cause changes in the structure of the electrode material and even failure, affecting the electrochemical performance of the electrode material.

[0089] Therefore, the embodiments of the present application provide an electrode material. By optimizing the design of the surface coating layer of the electrode material, the content of amorphous carbon in the coating layer can be effectively reduced, the graphitization degree of the coating layer can be improved, the catalytic oxidation of the electrolyte can be reduced, and the life and cycle performance of the battery cell can be improved.

[0090] In some embodiments, the electrode material can include a core and a carbon coating material. The core includes an electrode active material. The carbon coating material covers at least part of the surface of the core. The Raman spectrum of the coating layer has G peak and D peak, and I D / I Gless than or equal to 0.9.

[0091] In the present application, I G is the peak intensity of the G peak (SP 2 hybridized carbon atoms) in the Raman spectrum. D is the peak intensity of the D peak (SP 3 hybridized carbon atoms) in the Raman spectrum. D G is the ratio of the peak intensity of the G peak (SP 3 hybridized carbon atoms) to the peak intensity of the D peak (SP 2 hybridized carbon atoms), which can reflect the graphitization degree of the coating layer. G and I D can be measured by methods known in the art, for example, can be determined by Raman spectroscopy, specifically: the battery monomer can be disassembled to obtain a positive electrode sheet, the positive electrode sheet can be scraped to obtain a powder containing a positive electrode material, and the powder can be subjected to Raman spectrum detection, and by peak separation of the Raman spectrum, I D and I G can be obtained.

[0092] In the embodiments of the present application, by limiting the value of I D / I G of the carbon-coated material to be within the above range, the smaller the value, the more SP 2 hybridized carbon accounts for in the carbon-coated material, which has a higher graphitization degree, a smaller catalytic oxidation effect on the electrolyte, and a more compact structure of the coating layer that can be formed, i.e., the electrode material can have better conductivity, ensuring the lithium ion path while reducing the catalytic oxidation of carbon in the coating layer on the electrolyte, improving the cycle stability of the electrolyte, and thus improving the cycle life of the battery monomer.

[0093] In some embodiments, the carbon-coated material can form a uniform coating layer on at least part of the surface of the core.

[0094] In some embodiments, the uniformity of the coating layer is characterized by a thickness value coefficient of variation, and the thickness value coefficient of variation of the coating layer is less than or equal to 8%. Alternatively, the thickness value coefficient of variation of the coating layer can be 5% to 8%.

[0095] ​In the present application, the uniformity of the coating layer refers to the uniformity of the coating layer formed by the carbon-coated material on the surface of the core, which can be detected by the following method: the thickness of the coating layer on the surface of the electrode material particles at different positions is sampled and detected. Specifically, the sampling can be carried out at intervals on the surface of the electrode material particles, and the number of sampling points can be 10, 20, 30 or other values. The sampling points can be uniformly distributed at intervals on the surface of the electrode material particles. Thus, the thickness values of the coating layer at different points are obtained, and the average value and the standard deviation of all thickness value data are calculated respectively. Then, the uniformity of the coating is reflected by calculating the thickness value coefficient of variation (COV), COV (%) = (standard deviation / average value)*100%. The smaller the value of COV, the smaller the fluctuation between the data, indicating that the difference in thickness value of the coating layer at different sampling points is smaller, and the uniformity of the coating is better.

[0096] In the embodiments of the present application, the coating layer has high uniformity, indicating that the carbon-coated material forms a uniform and dense coating structure on the surface of the core, thereby further reducing the contact between the core and the electrolyte, reducing the catalytic oxidation of the electrolyte, and improving the cycle performance of the battery cell.

[0097] In some embodiments, the thickness of the coating layer can be 2 nm to 5 nm. For example, the thickness of the coating layer can be 2 nm, 3 nm, 4 nm, 5 nm, or a range consisting of any of the above values. The thickness of the coating layer in the above range is beneficial to form a more stable and dense coating structure, which can further improve the structural stability and electrochemical performance of the electrode material.

[0098] In some embodiments, the proportion of unsaturated carbon atoms in the carbon-coated material relative to the total number of carbon atoms is greater than 50%.

[0099] In the present application, unsaturated carbon atoms refer to carbon atoms that form bonds with another atom through double bonds or triple bonds. The other atom can be a carbon atom, an oxygen atom, a nitrogen atom, or any atom that can form a bond with a carbon atom through a double bond or a triple bond. The proportion of unsaturated carbon atoms relative to the total number of carbon atoms can be calculated according to the unsaturation degree of the carbon-coated material. The unsaturation degree, also known as the hydrogen deficiency index or the ring plus double bond index, is a quantitative indicator of the unsaturation degree of an organic compound molecule. That is, compared with an equal number of open-chain alkanes in an organic compound molecule, for every 2 hydrogen atoms reduced, the unsaturation degree of the organic compound increases by 1. For example, for an organic compound with the chemical formula C x H y or C x H y O z if y < 2x + 2, the organic compound has a certain unsaturation degree, the unsaturation degree Ω = x + 1 - y / 2, and the proportion of unsaturated carbon atoms relative to the total number of carbon atoms η = Ω / x*100%. For example, glucose (C6H12 O6) is 1, and the ratio of the number of unsaturated carbon atoms to the total number of carbon atoms is 16.7%; the unsaturation of benzene (C6H6) is 4, and the ratio of the number of unsaturated carbon atoms to the total number of carbon atoms is 66.7%.

[0100] In the embodiments of the present application, carbon-coated materials with a high proportion of unsaturated carbon atoms are used. These carbon-coated materials contain more SP 2 hybrid carbon, SP 2 Hybrid carbon itself has relatively low catalytic activity, and a high degree of graphitization of the coating layer can be obtained at a relatively low sintering temperature, which can effectively reduce the content of amorphous carbon in the coating layer, reduce the catalytic oxidation of the coating layer on the electrolyte, thereby reducing the interface reaction and the oxidation and decomposition of the electrolyte, and further improving the life of the battery cell. In addition, by using the above-mentioned carbon-coated materials with a higher content of unsaturated carbon as the raw material of the coating layer, a more dense and uniform coating layer can be obtained.

[0101] Figure 4 Raman spectra of the coating layer in the electrode material obtained in some embodiments of the present application are shown. It can be seen that, by using carbon-coated materials with a higher content of unsaturated carbon as the raw material of the coating layer, the coating layer obtained has a lower I D / I G value, i.e., a higher degree of graphitization.

[0102] Figure 5 and Figure 6 TEM images of the electrode material with the coating layer prepared by using β-naphthalenesulfonic acid and glucose as raw materials, respectively, are shown. It can be seen that the coating layer formed by β-naphthalenesulfonic acid is more dense and has a more uniform thickness.

[0103] By controlling the proportion of unsaturated carbon atoms in the carbon-coated material to be within the above range, a coating layer with a higher degree of graphitization can be obtained, which further reduces the content of amorphous carbon in the coating layer, and thus can reduce the catalytic oxidation of the electrolyte and improve the cycle life of the battery cell.

[0104] In some embodiments, the carbon-coated material includes one or more of carbon-containing compounds containing unsaturated bonds.

[0105] Optionally, the unsaturated bond can include one or more of a C=C bond, a C≡C bond, a C=O bond, a C=N bond, and a benzene ring.

[0106] In some embodiments, the carbon-coated material can include one or more of graphene, styrene-butadiene rubber, phenolic resin, condensed polycyclic aromatic hydrocarbon and its derivatives, benzoic acid and its derivatives, naphthalenesulfonic acid and its derivatives, lignin, tannic acid.

[0107] The carbon-coated material structure contains abundant unsaturated bonds, and the content of unsaturated carbon atoms is high. When the material is used as a coating layer, it can be sintered at a lower temperature to form a coating layer with high graphitization degree, and the content of amorphous carbon in the coating layer is low, which is beneficial to reduce the catalytic oxidation of carbon in the coating layer to the electrolyte, and further improve the cycle stability of the battery cell.

[0108] In some embodiments, the volume distribution particle size Dv50 of the electrode material can be 0.5 μm to 15 μm, and optionally 1.2 μm to 13.5 μm. Illustratively, the volume distribution particle size of the electrode material can be 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11.0 μm, 11.5 μm, 12.0 μm, 12.5 μm, 13.0 μm, 13.5 μm, 14.0 μm, 14.5 μm, 15.0 μm, or a range consisting of any of the above values.

[0109] The volume distribution particle size Dv50 can be determined by methods and instruments known in the art, for example, according to GB / T 19077-2016 "Particle Size Analysis-Laser Diffraction Method", using a laser diffraction instrument.

[0110] When the volume distribution particle size Dv50 of the electrode material is within the above range, the active ions have a suitable diffusion distance, which can further improve the electrochemical performance of the battery cell.

[0111] In some embodiments, the specific surface area of the electrode material can be 10 m 2 / g to 15 m 2 / g, and optionally 12 m 2 / g to 14 m 2 / g. Illustratively, the specific surface area of the electrode material can be 10 m 2 / g, 11 m 2 / g, 12 m 2 / g, 13 m 2 / g, 14 m 2 / g, 15 m 2 / g, or a range consisting of any of the above values.

[0112] The specific surface area of the material is in the meaning known in the art and can be determined by using instruments and methods known in the art. For example, the nitrogen adsorption specific surface area analysis test can be tested according to GB / T 19587-2017, and the BET (Brunauer Emmett Teller) method is used for calculation. The nitrogen adsorption specific surface area analysis test can be performed by using a TRISTAR II 3020 type specific surface area and porosity analyzer of the American Micromeritics company.

[0113] The specific surface area of the electrode material is in the above range, which has better electrolyte wettability, and can further improve the electrochemical performance of the battery cell.

[0114] In some embodiments, the carbon content of the electrode material can be 1.0% to 2.0%. The carbon content of the electrode material refers to the mass percentage of carbon elements in the electrode material. By limiting the carbon content in the electrode active material in the above range, the electrode material has good electrical conductivity, which can further improve the electrochemical performance of the battery cell. In the embodiments of the present application, the carbon content of the electrode material refers to the carbon content of the positive electrode material.

[0115] In some embodiments, the electrode material can be prepared by the following method:

[0116] S10, respectively providing a core and a carbon source, wherein the proportion of unsaturated carbon atoms in the carbon source relative to the total number of carbon atoms is greater than or equal to 50%;

[0117] S20, forming a coating layer of the carbon source on at least part of the surface of the core.

[0118] In some embodiments, step S20 can include:

[0119] S21, dispersing the carbon source in a dispersant to obtain a carbon source dispersion liquid;

[0120] S22, adding the core into the dispersion liquid to cover the carbon source on at least part of the surface of the core, and drying to obtain a pre-coated material;

[0121] S23, drying the pre-coated material and then performing sintering treatment, crushing and sieving after sintering to obtain the electrode material.

[0122] In some embodiments, the mass ratio of the carbon source to the core can be (0.5-2):10, and can be (0.6-8):10. More preferably, it can be (0.8-6):10.

[0123] The mass ratio of the carbon source to the core is limited in the above range, which is beneficial to form a stable and dense coating layer on the surface of the core.

[0124] In some embodiments, the carbon source can include one or more of graphene, condensed ring aromatic hydrocarbons and derivatives thereof, styrene butadiene rubber, phenol formaldehyde resin, benzoic acid and derivatives thereof, naphthalene sulfonic acid and derivatives thereof, lignin, tannic acid.

[0125] The above-mentioned carbon sources all contain abundant unsaturated bonds and have a high content of unsaturated carbon atoms. When used as a raw material for the coating layer, the carbon source can be sintered at a low temperature to form a coating layer with a high graphitization degree, and the content of amorphous carbon in the coating layer is low, which is conducive to reducing the catalytic oxidation of the electrolyte by the carbon in the coating layer, and further improving the cycle stability of the battery cell.

[0126] In some embodiments, the dispersant can be water.

[0127] In some embodiments, the drying method can include one or more of spray drying, vacuum drying, and heat drying.

[0128] In some embodiments, the sintering temperature can be 600-800°C. Illustratively, the sintering temperature can be 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, or a range defined by any two of the above values.

[0129] In the embodiments of the present application, the temperature for preparing the coating layer is limited to below 800°C. Since the selected carbon source has a high SP 2 hybridization degree, it can be sintered at a low temperature to obtain a coating layer with a high SP 2 hybridization degree, which reduces the catalytic oxidation of the electrolyte and improves the electrochemical performance of the battery cell. At the same time, the low sintering temperature can reduce the impact of high temperature on the electrode active material, which is conducive to maintaining the structural stability of the electrode active material.

[0130] In some embodiments, the holding time of the sintering process can be 8-12 h. Illustratively, the holding time can be 8 h, 9 h, 10 h, 11 h, 12 h, or a range defined by any two of the above values.

[0131] In some embodiments, the heating rate of the sintering process can be 3-8°C / min. Illustratively, the heating rate can be 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, or a range defined by any two of the above values.

[0132] In some embodiments, the electrode active material is a positive electrode active material, and the electrode material can be used for a positive electrode sheet.

[0133] [Positive electrode sheet]

[0134] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0135] In some embodiments, the positive electrode active material can include one or more of lithium-containing phosphates, layered lithium-containing transition metal oxides, Prussian blue type compounds, polyanion type compounds, and sodium transition metal oxides.

[0136] If the positive electrode active material is one or more of lithium-containing phosphates and layered lithium-containing transition metal oxides, the positive electrode active material can be used in lithium ion battery cells; if the positive electrode active material is one or more of Prussian blue type compounds, polyanion type compounds, and sodium transition metal oxides, the positive electrode active material can be used in sodium ion battery cells.

[0137] The lithium-containing phosphates can include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and modified compounds of each thereof.

[0138] Examples of the layered lithium-containing transition metal oxide can include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds of each thereof.

[0139] In some embodiments, the layered lithium-containing transition metal oxide can include Ni elements. The molar amount of the Ni elements can account for 70% or more of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; optionally, the molar amount of the Ni elements can account for 80% or more of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; more optionally, the molar amount of the Ni elements can account for 90% or more of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0140] The higher the content of the Ni elements in the layered lithium-containing transition metal oxide, the higher the energy density of the battery cell.

[0141] In some embodiments, the layered lithium-containing transition metal oxide can include Li a Ni b Co c M d O e A fWherein, 0 < a ≤ 1.2; 0.8 ≤ b < 1; 0 < c < 1; 0 < d < 1; 1 ≤ e ≤ 2; 0 ≤ f ≤ 1; M includes, but is not limited to, one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B; A includes, but is not limited to, one or more of N, F, S, and Cl. This can further improve the energy density of individual battery cells.

[0142] In some embodiments, as an example, layered lithium-containing transition metal oxides may include, but are not limited to, LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.06 Mn 0.04 O2, LiNi 0.92 Co 0.06 Mn 0.02 O2, LiNi 0.96 Co 0.02 Mn 0.02 One or more of O2.

[0143] During the charging and discharging process of a battery cell, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar Li content may change when the positive electrode active material is applied to the battery cell.

[0144] In some embodiments, as an example, sodium transition metal oxides may include, but are not limited to:

[0145] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0146] Na 0.67 Mn 0.7 Ni z M2 0.3-z O2, where M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn, and Ba, and 0 < z ≤ 0.1;

[0147] Na a Li b Ni c Mn d Fe e O2, where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3,

[0148] 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0149] In some embodiments, by way of example, the polyanionic compound may include, but is not limited to:

[0150] A 1 f M 3 g (PO4) i O j X 1 3-j , where A is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, and X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, and 0 ≤ j ≤ 2;

[0151] Na n M 4 PO4X 2 where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, and X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0152] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, and 0 < q ≤ 2;

[0153] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0154] In some embodiments, by way of example, Prussian blue compounds may include, but are not limited to:

[0155] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + , NH4 + , one or more of alkali metal cations and alkaline earth metal cations, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ and Ra 2+ one or more of, M 6 and M 7 are each independently cations of one or more transition metal elements of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn and W. Optionally, A is Li + , Na + and K + one or more of, M 6 is cations of one or more transition metal elements of Mn, Fe, Co, Ni and Cu, M 7 is cations of one or more transition metal elements of Mn, Fe, Co, Ni and Cu.

[0156] In the enumeration of the positive electrode active materials in the embodiments of the present application, the molar content of O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0157] The modified compounds of the above positive electrode active materials may be doping modification and / or surface coating modification of the positive electrode active materials.

[0158] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0159] In some implementations, the weight percentage of the binder in the positive electrode film layer is greater than or equal to 0.5%, which is beneficial for obtaining good adhesion performance.

[0160] In some embodiments, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0161] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be made by forming a metal material, such as aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, on the polymer substrate. The polymer substrate may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and other substrates.

[0162] In some embodiments, the thickness of the positive current collector is from 4 μm to 20 μm. It is optionally from 6 μm to 18 μm, and more preferably from 8 μm to 16 μm.

[0163] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0164] In some embodiments, the electrode active material is a negative electrode active material. In this case, the electrode material can be used as a negative electrode sheet.

[0165] [Negative electrode plate]

[0166] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode film layer located on at least one side of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0167] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector can be made of materials such as metal foil, carbon-coated metal foil, or porous metal plate, and copper foil is optional.

[0168] As an example, the negative electrode active material may include one or more of the following: artificial graphite, natural graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, and silicon-carbon composites.

[0169] Silicon-based composite materials can be prepared by methods known in the art. For example, they can be prepared by vapor deposition using graphite and silicon materials as raw materials.

[0170] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0171] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0172] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0173] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one side of the polymeric material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymeric material substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0174] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer sandwiched between the negative electrode current collector and the negative electrode film layer and located on the surface of the negative electrode current collector, which may be composed of a conductive agent and a binder; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0175] The negative electrode sheet can be prepared as follows: The negative electrode active material, negative electrode binder, negative electrode conductive agent, and optional other additives are dispersed in a solvent and stirred evenly to form a negative electrode slurry; the negative electrode slurry is coated onto a negative electrode current collector, and after drying, rolling, and other processes, a negative electrode sheet is formed. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0176] [Electrolytes]

[0177] A single battery cell includes an electrolyte.

[0178] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0179] In some embodiments, the electrolyte includes anion, which may include bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), dioxaborate anion (BOB) - ), difluorooxalate borate anion (DFOB) - ), difluorodioxanol phosphate anion (DFOP) - ), tetrafluorooxalate phosphate anion (TFOP) - ), difluorophosphate anion (PO2F2) - ), hexafluorophosphate anion (PF6) - ), tetrafluoroborate anion (BF4) - ), hexafluoroarsenate anion (AsF6) - ), trifluoromethanesulfonate anion (CF3SO3) - One or more of the following.

[0180] In some embodiments, the electrolyte includes cations, which may include one or more of lithium ions and sodium ions.

[0181] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or higher, optionally 0.7 mol / L or higher, and further optionally 4 mol / L or lower, optionally 2.5 mol / L or lower, or 1.7 mol / L or lower. When the concentration of the electrolyte salt is within the above range, the electrolyte can have a suitable ionic conductivity.

[0182] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, and nitriles. Esters may include, but are not limited to, one or more of carbonates, phosphate esters, carboxylic esters, sulfate esters, and sulfonates. Carbonates may include cyclic carbonates and / or chain carbonates; optionally, carbonates may include both cyclic and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0183] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butene carbonate, ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, H(CF2)2OCH3, C4F9O CH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyl One or more of the following: decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecylfluorohexyl methyl ether, 5-trifluoromethyl dodecylfluorohexyl ethyl ether, 5-trifluoromethyl dodecylfluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecylfluorooctyl methyl ether, 7-trifluoromethyl hexadecylfluorooctyl ethyl ether, and 7-trifluoromethyl hexadecylfluorooctyl propyl ether.

[0184] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0185] [Isolation membrane]

[0186] In some embodiments, the electrode assembly includes a separator. This application does not impose any particular limitation on the type of separator; any known porous membrane with good chemical and mechanical stability can be selected.

[0187] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0188] Example

[0189] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0190] Example 1

[0191] Positive electrode tab

[0192] S10, disperse the carbon source β-naphthalenesulfonic acid in an appropriate amount of water and stir thoroughly at 8000 r / min for 2 h to obtain a carbon source dispersion;

[0193] S20, add the positive electrode active material lithium iron phosphate (LiFePO4) to the carbon source dispersion, the mass ratio of the positive electrode active material to the carbon source is 10:1, and continue stirring and mixing for 2 hours;

[0194] S30, the mixture in step S20 is spray-dried under stirring, and the pre-coated material is obtained after drying;

[0195] S40, the pre-coated material is placed in an atmosphere furnace for sintering. The sintering atmosphere is argon, the sintering temperature is 700℃, the heating rate is 5℃ / min, and the sintering time is 10h. The sintered material is then obtained as the positive electrode material.

[0196] S50, the above-prepared positive electrode material, conductive carbon black, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 90:5:5 and then added to the solvent N-methylpyrrolidone (NMP) to uniformly disperse and obtain a positive electrode slurry. The positive electrode slurry is coated onto the surface of the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0197] Negative electrode tab

[0198] A negative electrode slurry is prepared by uniformly mixing graphite (a negative electrode active material), Super P (a conductive agent), carboxymethyl cellulose (CMC) (a thickener), and styrene-butadiene rubber (SBR) (a binder) in deionized water at a mass ratio of 80:15:3:2. The negative electrode slurry is then uniformly coated onto copper foil (a current collector) and dried at 85°C. After cold pressing and slitting, the negative electrode sheet is obtained.

[0199] Examples 2 to 9

[0200] The difference from Example 1 is that the composition parameters of the cathode material are different, as detailed in Table 1.

[0201] Example 10

[0202] The positive electrode material is the same as in Example 1, except that the negative electrode material is prepared by the following method:

[0203] S10, disperse the carbon source β-naphthalenesulfonic acid in an appropriate amount of water and stir thoroughly at 8000 r / min for 2 h to obtain a carbon source dispersion;

[0204] S20, add graphite, the negative electrode active material, to the carbon source dispersion. The mass ratio of the negative electrode active material to the carbon source is 10:1. Continue stirring and mixing for 2 hours.

[0205] S30, the mixture in step S20 is spray-dried under stirring, and the pre-coated material is obtained after drying;

[0206] S40, the pre-coated material is placed in an atmosphere furnace for sintering. The sintering atmosphere is argon, the sintering temperature is 700℃, the heating rate is 5℃ / min, and the sintering time is 10h. The sintered material is then used as the negative electrode material.

[0207] Example 11

[0208] The negative electrode material is the same as in Example 10, except that the composition parameters of the positive electrode material are different, as detailed in Table 1.

[0209] Comparative Examples 1 to 4

[0210] The difference from Example 1 is that the composition parameters of the cathode material are different, as detailed in Table 1.

[0211] Comparative Example 5

[0212] The difference from Example 1 is that the positive electrode material does not have a coating layer.

[0213] Test section

[0214] A coin cell battery was fabricated by stacking the positive electrode, negative electrode, and separator in sequence and injecting electrolyte. The separator was made of polyethylene (PE) membrane with a thickness of 13 μm. The electrolyte solvent was a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The electrolyte salt was LiPF6 (NaPF6 in Example 6) with a concentration of 1 mol / L.

[0215] 1. Uniformity of electrode material coating

[0216] The thickness of the coating layer on the surface of the electrode material particles was sampled at different locations at intervals, with the sampling points referring to... Figure 7 The number of sampling points is 20. The sampling points are evenly distributed on the surface of the electrode material particles to obtain the thickness value of the coating layer at different points. The average and standard deviation of all thickness values ​​are calculated respectively. Then, the coating uniformity is reflected by calculating the coefficient of variation (COV) of the thickness value. COV (%) = (standard deviation / average) * 100%.

[0217] 2. Battery cell initial efficiency and specific capacity testing

[0218] After being charged at a constant current of 0.1C to the upper limit cutoff voltage (3.65V for lithium iron phosphate and 4.2V for lithium iron manganese phosphate), it is charged at a constant voltage to 0.05C and discharged at a constant current of 0.1C to the lower limit cutoff voltage. The ratio of the first discharge capacity to the first charge capacity of a battery cell is used as the first efficiency of the battery cell, and the ratio of the first discharge capacity to the mass of the active material is used as the specific capacity of the battery cell.

[0219] 3. Battery cell life test

[0220] The battery cells were charged at a constant current of 0.1C to the upper limit cutoff voltage and then stored in a 60°C oven. Every so often, the cells were taken out to test their reversible capacity and the ratio of the reversible capacity to the initial capacity after 60 days of storage was recorded.

[0221] The test results are detailed in Table 1.

[0222]

[0223] Based on the data in Table 1, the electrode material prepared by using a carbon coating material with a high content of unsaturated carbon atoms as the coating layer of the electrode active material can effectively improve the capacity and lifespan of the battery cell.

[0224] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized by, The electrode tab comprises a current collector and an electrode film layer on at least one side of the current collector, the electrode film layer comprising an electrode material, the electrode material comprising: The inner core comprises an electrode active material; The carbon-coated material covers at least part of the surface of the inner core; The Raman spectrum of the carbon-coated material has a G peak and a D peak, and I D / I G is less than or equal to 0.

9.

2. The battery cell of claim 1, wherein, The carbon-coated material forms a uniform coating layer on at least part of the surface of the inner core.

3. The battery cell of claim 2, wherein, The uniformity of the coating layer is characterized by a thickness value coefficient of variation, and the thickness value coefficient of variation of the coating layer is less than or equal to 8%.

4. The battery cell of claim 3, wherein, The thickness value coefficient of variation of the coating layer is 5% to 8%.

5. The battery cell according to any one of claims 2 to 4, characterized in that, The thickness of the coating layer is 2nm to 5nm.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The molar proportion of unsaturated carbon atoms in the carbon-coated material relative to the total number of carbon atoms is greater than 50%.

7. The battery cell of any one of claims 1 to 6, wherein, The carbon-coated material comprises one or more of carbon-containing compounds containing unsaturated bonds.

8. The battery cell of any one of claims 1 to 7, wherein, The carbon-coated material comprises one or more of graphene, styrene-butadiene rubber, phenolic resin, condensed polycyclic aromatic hydrocarbon and its derivatives, benzoic acid and its derivatives, naphthalene sulfonic acid and its derivatives, lignin, tannic acid.

9. The battery cell of any one of claims 1 to 8, wherein, The electrode active material is a positive electrode active material.

10. The battery cell of claim 9, wherein, The positive electrode active material comprises one or more of layered lithium-containing transition metal oxides, lithium-containing phosphates, prussian blue compounds, polyanion compounds, sodium transition metal oxides.

11. The battery cell according to claim 9 or 10, characterized in that The electrode material satisfies at least one of the following conditions (1) to (3): (1) The volume distribution particle size Dv50 of the electrode material is 0.5μm to 15μm; (2) the specific surface area of the electrode material is 10 m 2 / g to 15 m 2 / g; (3) The carbon content of the electrode material is 1.0% to 2.0%.

12. The battery cell of any one of claims 1 to 8, wherein, The electrode active material is a negative electrode active material.

13. The battery cell of claim 12, wherein, The negative electrode active material comprises one or more of artificial graphite, natural graphite, mesophase carbon microbeads, hard carbon, soft carbon, silicon, silicon-carbon composite material.

14. A battery device characterized by comprising: The battery device comprises the battery cell of any one of claims 1 to 13.

15. An electrical device, comprising: The battery device comprises the battery cell of claim 14.

16. An electrode material, characterized by The battery device comprises: The inner core comprises an electrode active material; The carbon-coated material covers at least part of the surface of the inner core, wherein The Raman spectrum of the carbon-coated material has a G peak and a D peak, and I D / I G is less than or equal to 0.

9.

17. The electrode material of claim 16, wherein, The carbon-coated material forms a uniform coating layer on at least part of the surface of the inner core.

18. The battery cell of claim 16, wherein, The uniformity of the coating layer is characterized by a thickness value coefficient of variation, and the thickness value coefficient of variation of the coating layer is less than or equal to 8%.

19. The battery cell of claim 17, wherein, The thickness value coefficient of variation of the coating layer is 5% to 8%.

20. The electrode material of any one of claims 17-19, wherein, The thickness of the coating layer is 2nm to 5nm. The molar proportion of unsaturated carbon atoms in the carbon-coated material relative to the total number of carbon atoms is greater than 50%.

21. The electrode material according to any one of claims 16 to 20, wherein, The carbon-coated material comprises one or more of carbon-containing compounds containing unsaturated bonds.

22. The electrode material of claim 21, wherein, The carbon-coated material comprises one or more of graphene, styrene-butadiene rubber, phenolic resin, condensed polycyclic aromatic hydrocarbon and its derivatives, benzoic acid and its derivatives, naphthalene sulfonic acid and its derivatives, lignin, tannic acid.

23. The electrode material of any one of claims 16 to 22, wherein, The battery device comprises the following steps:

24. A method of producing an electrode material, characterized by, The inner core and the carbon source are provided respectively, wherein the proportion of unsaturated carbon atoms in the carbon source relative to the total number of carbon atoms is greater than or equal to 50%; The carbon source is coated on at least part of the surface to obtain the electrode material. The mass ratio of the carbon source to the inner core is (0.5-2):

10.

25. The method of claim 24, wherein, ​ 26. The method of manufacturing according to claim 24 or 25, wherein, The carbon source comprises one or more of graphene, condensed ring aromatic hydrocarbon and derivatives thereof, styrene butadiene rubber, phenol formaldehyde resin, benzoic acid and derivatives thereof, naphthalene sulfonic acid and derivatives thereof, lignin, tannic acid.

27. The method of making according to any one of claims 24 to 26, wherein, The coating of the carbon source on at least part of the surface to obtain the electrode material comprises: forming a pre-coating layer of the carbon source on at least part of the surface of the inner core to obtain a pre-coated material; sintering the pre-coated material to obtain the electrode material.

28. The preparation method according to claim 27, characterized in that, The sintering treatment is at a temperature of 600-800°C.

29. The preparation method of claim 27 or 28, wherein: the sintering treatment is for a time of 8-12h; and / or the sintering treatment is at a temperature increase rate of 3-8°C / min.

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