Lithium-ion battery and electric device

Abstract

A lithium-ion battery (100) and an electric device. The lithium-ion battery (100) comprises a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. The positive electrode sheet comprises a compound containing nickel and cobalt. The compound containing nickel and cobalt comprises a layered lithium-containing transition metal oxide, wherein the ratio of the molar amount of nickel to the total molar amount of the transition metal element is within the range of 0.50-0.75, and the ratio of the molar amount of cobalt to the total molar amount of the transition metal element is within the range of 0.05-0.20. The negative electrode sheet comprises a negative electrode active material, wherein the negative electrode active material comprises artificial graphite, and the gram capacity of the negative electrode active material is within the range of 345-400 mAh / g.

Description

Lithium-ion batteries and electrical equipment

[0001] This disclosure claims priority to Chinese patent application No. 2025100118533, filed on January 3, 2025, entitled “Lithium-ion Battery and Electrical Device”, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to the field of new energy technology, and in particular to a lithium-ion battery and electrical equipment. Background Technology

[0003] This section provides only background information relevant to this application and is not necessarily prior art.

[0004] Lithium-ion batteries are widely used in wireless communication, transportation, aerospace, and many other fields. With continuous technological advancements, lithium-ion batteries will continue to play a vital role and drive innovation in energy storage technology. For lithium-ion batteries, energy density and cycle life are crucial factors affecting their development.

[0005] Therefore, this invention is proposed. Summary of the Invention

[0006] In view of the technical problems existing in the background art, this application provides a lithium-ion battery and electrical device, which aims to improve the energy density and cycle life of lithium-ion batteries.

[0007] To achieve the above objectives, a first aspect of this application provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte.

[0008] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material. The positive electrode active material includes a nickel-cobalt compound, which includes a layered lithium-containing transition metal oxide. The ratio of the molar amount of nickel in the layered lithium-containing transition metal oxide to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide is in the range of 0.50 to 0.75, and the ratio of the molar amount of cobalt in the layered lithium-containing transition metal oxide to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide is in the range of 0.05 to 0.20.

[0009] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector; the negative electrode film layer includes a negative electrode active material; the negative electrode active material includes artificial graphite; wherein the specific capacity of the negative electrode active material is in the range of 345mAh / g to 400mAh / g.

[0010] The embodiments of this application improve the energy density and cycle life of lithium-ion batteries by controlling the specific composition of the positive electrode active material and the specific capacity of the negative electrode active material.

[0011] In some embodiments, layered lithium-containing transition metal oxides include Li a Ni b Co c M d O e A f Wherein, 0<a≤1.2, 0.50≤b≤0.75, 0.05≤c≤0.20, 0.05≤d≤0.45, b+c+d=1; 1≤e≤2; 0≤f≤1, e+f=2; M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, W, Nb, Sb and B, and A includes one or more of N, F, S and Cl.

[0012] The embodiments of this application, through the layered lithium-containing transition metal oxide of the above-described general chemical formula, can improve the structural stability of the layered lithium-containing transition metal oxide while maintaining a high energy density in lithium-ion batteries, thereby enabling lithium-ion batteries to have good cycle life.

[0013] In some embodiments, the nickel-cobalt compound includes nickel-cobalt compounds with a single crystal morphology.

[0014] The embodiments of this application improve the cycle life of lithium-ion batteries by using positive electrode active materials containing nickel-cobalt compounds with single-crystal morphology.

[0015] In some embodiments, the Dv50 of the positive electrode active material is in the range of 2.5µm to 5.5µm.

[0016] The embodiments of this application utilize positive electrode active materials with an average volume particle size Dv50 within the aforementioned range, enabling lithium-ion batteries to possess high energy density and cycle life.

[0017] In some embodiments, the specific capacity of the positive electrode active material is in the range of 185 mAh / g to 210 mAh / g.

[0018] The embodiments of this application improve the energy density of lithium-ion batteries by using positive electrode active materials within the above-mentioned specific capacity range.

[0019] In some embodiments, the mass percentage of nickel-cobalt compound is greater than or equal to 80% based on the total mass of the positive electrode active material.

[0020] The embodiments of this application improve the energy density of lithium-ion batteries by adjusting the mass ratio of nickel-cobalt element compounds based on the total mass of the positive electrode active material.

[0021] In some embodiments, the compaction density of the positive electrode film is in the range of 3.1 g / cc to 3.6 g / cc.

[0022] The embodiments of this application improve the energy density of lithium-ion batteries by using positive electrode film layers within the aforementioned compaction density range.

[0023] In some embodiments, the coating weight of the positive electrode film is 160 mg / 1540.25 mm. 2 ~270mg / 1540.25mm 2 Within the range.

[0024] The embodiments of this application improve the energy density of lithium-ion batteries by employing positive electrode film layers within the above-described coating weight range.

[0025] In some embodiments, the mass percentage of artificial graphite is in the range of 80% to 98.5% based on the total mass of the negative electrode film.

[0026] The embodiments of this application improve the cycle life of lithium-ion batteries by using artificial graphite within the above-mentioned mass percentage range.

[0027] In some embodiments, the negative electrode active material also includes amorphous carbon.

[0028] The embodiments of this application regulate the battery performance of lithium-ion batteries by using anode active materials including amorphous carbon.

[0029] In some embodiments, based on the total mass of the negative electrode film, the mass percentage of amorphous carbon is less than or equal to 9.85%, and the mass percentage of artificial graphite is in the range of 72% to 98.5%.

[0030] The embodiments of this application, through the above-mentioned mass ratio of amorphous carbon and artificial graphite, enable lithium-ion batteries to still have good cycle life while controlling the battery performance.

[0031] In some embodiments, at least a portion of the surface of the artificial graphite is covered with amorphous carbon.

[0032] The embodiments of this application regulate the battery performance of lithium-ion batteries by using artificial graphite with at least a portion of its surface covered with amorphous carbon.

[0033] In some embodiments, the initial coulombic efficiency of the negative electrode active material is greater than or equal to 92%.

[0034] The embodiments of this application improve the cycle life of lithium-ion batteries by using negative electrode active materials within the first coulombic efficiency range described above.

[0035] In some embodiments, the compaction density of the negative electrode film is in the range of 1.5 g / cc to 1.8 g / cc.

[0036] The embodiments of this application improve the energy density of lithium-ion batteries by using negative electrode film layers within the aforementioned compaction density range.

[0037] In some embodiments, the coating weight of the negative electrode film is 100 mg / 1540.25 mm. 2 ~190mg / 1540.25mm 2 Within the range.

[0038] The embodiments of this application improve the energy density of lithium-ion batteries by employing negative electrode film layers within the above-described coating weight range.

[0039] In some embodiments, the negative electrode film layer includes a first negative electrode sub-film layer and a second negative electrode sub-film layer, the second negative electrode sub-film layer being disposed between the first negative electrode sub-film layer and the negative electrode current collector; the first negative electrode sub-film layer includes a first negative electrode active material, the first negative electrode active material including amorphous carbon and artificial graphite; the second negative electrode sub-film layer includes a second negative electrode active material, the second negative electrode active material including artificial graphite or the second negative electrode active material including amorphous carbon and artificial graphite; the specific capacity of the first negative electrode active material is in the range of 345 mAh / g to 395 mAh / g, and the specific capacity of the second negative electrode active material is in the range of 350 mAh / g to 400 mAh / g.

[0040] The embodiments of this application, by layering the negative electrode film and differentially controlling the specific capacity of each layer of negative electrode active material, still maintain good energy density while controlling the battery performance of lithium-ion batteries.

[0041] In some embodiments, based on the total mass of the first negative electrode film layer, the mass percentage of amorphous carbon in the first negative electrode film layer is in the range of 0.1% to 9.85%; based on the total mass of the second negative electrode film layer, the mass percentage of amorphous carbon in the second negative electrode film layer is in the range of 0% to 9.5%.

[0042] The embodiments of this application achieve good energy density while controlling the battery performance of lithium-ion batteries by adjusting the mass ratio of amorphous carbon in each layer of the negative electrode film.

[0043] In some embodiments, the Dv50 of the first negative electrode active material is less than the Dv50 of the second negative electrode active material.

[0044] The embodiments of this application, through the first and second negative electrode active materials within the Dv50 range described above, still exhibit good energy density while regulating the battery performance of lithium-ion batteries.

[0045] In some embodiments, the Dv50 of the first negative electrode active material is in the range of 8.5µm to 15.5µm; the Dv50 of the second negative electrode active material is in the range of 11µm to 20µm.

[0046] The embodiments of this application, through the first and second negative electrode active materials within the Dv50 range described above, still exhibit good energy density while regulating the battery performance of lithium-ion batteries.

[0047] In some embodiments, the electrolyte includes a solvent; the solvent includes a first solvent, which includes one or both of carboxylic acid ester solvents and chain carbonate solvents; the weight percentage of the first solvent is less than or equal to 30% based on the total weight of the solvents.

[0048] The embodiments of this application reduce the occurrence of film-forming side reactions and gas generation between the electrolyte and the negative electrode during battery cycling by adjusting the weight ratio of the first solvent in the electrolyte, thereby improving the film-forming stability of the electrolyte on the negative electrode sheet and enhancing the cycle life of the lithium-ion battery.

[0049] In some embodiments, the carboxylic acid ester solvent includes one or more of the following: γ-butyrolactone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, isobutyl propionate, pentyl propionate, isopentyl propionate, ethyl isopropionate, methyl butyrate, ethyl butyrate, ethyl isobutyrate, butyl butyrate, butyl isobutyrate, pentyl butyrate, isopentyl butyrate, ethyl valerate, ethyl isovalerate, propyl valerate, propyl isovalerate, and compounds in which the carboxylic acid ester solvent is partially or completely substituted.

[0050] The embodiments of this application use carboxylic acid ester solvents within the above-mentioned range. The high conductivity, low surface tension, and low viscosity of carboxylic acid ester solvents enhance the migration speed of lithium ions, facilitate sufficient and effective contact between the active material and the electrolyte, and regulate the battery performance of the lithium-ion battery.

[0051] In some embodiments, the chain carbonate solvent includes one or more of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, dipropyl carbonate, and compounds in which the chain carbonate solvent is partially or completely substituted.

[0052] The embodiments of this application use chain carbonate solvents within the above-mentioned range to regulate the battery performance of lithium-ion batteries.

[0053] In some embodiments, the electrolyte includes a lithium salt; the concentration of the lithium salt in the electrolyte is between 0.7 mol / L and 1.2 mol / L.

[0054] The embodiments of this application, by employing lithium salts of the above concentration, are beneficial to improving the film-forming stability of the electrolyte at the negative electrode, regulating the conductivity of the electrolyte, enhancing the migration rate of lithium ions, and improving the cycle life of lithium-ion batteries.

[0055] In some embodiments, the conductivity of the electrolyte is in the range of 7 mS / cm to 13 mS / cm.

[0056] The embodiments of this application improve the transport capability of lithium ions in the electrolyte and regulate the battery performance of lithium-ion batteries by using electrolytes within the above-mentioned conductivity range.

[0057] In some embodiments, the electrolyte injection coefficient is in the range of 2.0 g / Ah to 2.8 g / Ah.

[0058] The embodiments of this application improve the uniformity of electrolyte distribution inside the lithium-ion battery by using electrolytes within the above-mentioned electrolyte injection coefficient range, improve the film formation stability of electrolytes on the negative electrode sheet, and enhance the cycle life of the lithium-ion battery.

[0059] Secondly, embodiments of this application provide an electrical device including any of the lithium-ion batteries provided in the first aspect. The electrical device provided by the embodiments of this application has at least the same advantages as lithium-ion batteries, namely, improved battery life. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. Other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 is a schematic diagram of the vehicle structure provided in an embodiment of this application;

[0062] Figure 2 is an exploded structural diagram of a lithium-ion battery provided in an embodiment of this application;

[0063] Figure 3 is an exploded structural diagram of a battery cell provided in an embodiment of this application.

[0064] Explanation of icon numbers:

[0065] 1000-Vehicle, 100-Lithium-ion battery, 200-Controller, 300-Motor, 10-Box, 20-Battery cell, 11-First part, 12-Second part, 21-End cap, 22-Housing shell, 23-Electrode assembly, 21a-Electrode terminal.

[0066] Embodiments of the present invention

[0067] The present application will be further described below with reference to specific embodiments. It should be understood that these specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0068] For the sake of brevity, this article only discloses some specific numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0069] In this description, unless otherwise stated, the term "or" is inclusive. That is, the phrase "A or (or) B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0070] In the description of this article, it should be noted that, unless otherwise stated, "above" and "below" include the number itself, and "several" in "one or more" means two or more.

[0071] Unless otherwise stated, the terms used in this application have their common meanings in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0072] Lithium-ion batteries using lithium phosphates with an olivine structure as the positive electrode active material have advantages such as high safety and long cycle life, but suffer from low energy density. Lithium-ion batteries using nickel-cobalt compounds as the positive electrode active material have the advantage of high energy density, but suffer from poor structural stability and low cycle life. Therefore, improving the energy density and cycle life of lithium-ion batteries is of great significance to their development.

[0073] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use lithium-ion batteries, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0074] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0075] Please refer to Figure 1, which is a structural schematic diagram of a vehicle provided in an embodiment of this application.

[0076] Referring to Figure 1, vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A lithium-ion battery 100 is installed inside vehicle 1000, which can be located at the bottom, front, or rear of vehicle 1000. The lithium-ion battery 100 can be used to power vehicle 1000; for example, it can serve as the operating power source for vehicle 1000. Vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the lithium-ion battery 100 to supply power to the motor 300, for example, to meet the power needs of vehicle 1000 during startup, navigation, and driving.

[0077] In some embodiments of this application, the lithium-ion battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0078] Please refer to Figure 2, which is a schematic diagram of the exploded structure of a lithium-ion battery provided in an embodiment of this application.

[0079] Referring to Figure 2, the lithium-ion battery 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, collectively defining a space for accommodating the battery cell 20. The second portion 12 can be a hollow structure with one open end, and the first portion 11 can be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 together define the space. Alternatively, both the first portion 11 and the second portion 12 can be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0080] In the lithium-ion battery 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the casing 10. Alternatively, the lithium-ion battery 100 can also consist of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module, and then these battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the casing 10. The lithium-ion battery 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0081] Among them, the battery cell 20 can be in the form of a cylinder, a flat shape, a cuboid, or other shapes.

[0082] Please refer to Figure 3, which is an exploded structural diagram of a battery cell provided in an embodiment of this application.

[0083] Referring to Figure 3, the battery cell 20 refers to the smallest unit that makes up the lithium-ion battery 100. The battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0084] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, giving battery cell 20 higher structural strength and improved safety performance. Functional components such as electrode terminals 21a can be provided on end cap 21. Electrode terminals 21a can be used for electrical connection with electrode assembly 23 to output or input electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0085] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 closes the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The housing 22 can be made of various materials, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, and plastic.

[0086] Electrode assembly 23 is the component in the battery cell 20 where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the cell assembly, while the portions of the positive and negative electrode sheets without active material each constitute a tab. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery cell 20, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals to form a current loop.

[0087] To achieve the above objectives, a first aspect of this application provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material. The positive electrode active material includes a nickel-cobalt compound, which comprises a layered lithium-containing transition metal oxide. The ratio of the molar amount of nickel in the layered lithium-containing transition metal oxide to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide is in the range of 0.50 to 0.75, and the ratio of the molar amount of cobalt in the layered lithium-containing transition metal oxide to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide is in the range of 0.05 to 0.20. The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector; the negative electrode film layer includes a negative electrode active material; the negative electrode active material includes artificial graphite; wherein the specific capacity of the negative electrode active material is in the range of 345mAh / g to 400mAh / g.

[0088] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on one surface of the positive current collector. In some embodiments, the positive electrode includes a positive current collector and two positive electrode film layers, one of which is disposed on one surface of the positive current collector, and the other is disposed on the opposite surface of the positive current collector where the aforementioned positive electrode film layer is disposed. In some embodiments, the positive electrode film layer is a single-layer film layer. In some embodiments, the positive electrode film layer is a multilayer film layer, as specifically configured as needed.

[0089] Layered lithium-containing transition metal oxides have a well-known meaning. In some embodiments, examples of layered lithium-containing transition metal oxides may 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 their respective modified compounds. In some embodiments, the modified compound may be a new compound formed by doping and / or surface coating modification of the above-mentioned layered lithium-containing transition metal oxides.

[0090] By controlling the ratio of the molar amount of nickel to the total molar amount of transition metal elements in layered lithium-containing transition metal oxides within the range of 0.50 to 0.75, nickel-lithium mixing can be reduced while maintaining high energy density in lithium-ion batteries, thereby improving the structural stability of layered lithium-containing transition metal oxides and ultimately enhancing the cycle life of lithium-ion batteries.

[0091] By adjusting the ratio of the molar amount of cobalt to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide within the range of 0.05 to 0.20, the layered lithium-containing transition metal oxide can exhibit a higher voltage plateau and better structural stability, thereby improving the energy density and cycle life of lithium-ion batteries.

[0092] It should be noted that the ratios of the molar amount of nickel to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide, and the ratios of the molar amount of cobalt to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide, in the embodiments of this application, can be determined using instruments and methods known in the art. For example, an ICP inductively coupled plasma atomic emission spectrometer can be used to measure the elemental composition and content in the positive electrode active material, obtain the molar amounts of nickel, cobalt, and transition metal elements in the layered lithium-containing transition metal oxide, and calculate the ratios of the molar amounts of nickel and cobalt to the total molar amounts of transition metal elements in the layered lithium-containing transition metal oxide.

[0093] In some embodiments, the positive electrode active material may include, in addition to the nickel-cobalt-containing compounds provided above, other existing positive electrode active materials to regulate the battery performance of the lithium-ion battery. For example, other existing positive electrode active materials may be lithium phosphates with an olivine structure. In some embodiments, the nickel-cobalt-containing compounds may include, in addition to the layered lithium-containing transition metal oxides provided above, other existing nickel-cobalt-containing compounds.

[0094] In some embodiments, the positive electrode film layer further includes a positive electrode conductive agent and a positive electrode binder.

[0095] The positive electrode conductive agent imparts conductivity to the positive electrode. The positive electrode conductive agent can include any existing conductive material. For example, the positive electrode conductive agent includes, but is not limited to, one or more of the following: carbon-based materials (e.g., natural graphite, conductive graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), and conductive polymers (e.g., polyphenylene derivatives).

[0096] Positive electrode binders improve the adhesion stability of the positive electrode film and reduce the probability of powder shedding. For example, positive electrode binders may include one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), lithium-ionized polyacrylic acid (PAALi), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0097] Artificial graphite refers to graphite materials obtained through organic carbonization followed by high-temperature graphitization. Due to its fewer defects, artificial graphite is used as a negative electrode active material in negative electrode sheets, which helps to improve the cycle life of lithium-ion batteries.

[0098] The specific capacity of the negative electrode active material can be 345mAh / g, 350mAh / g, 355mAh / g, 360mAh / g, 365mAh / g, 370mAh / g, 375mAh / g, 380mAh / g, 385mAh / g, 390mAh / g, 395mAh / g, 400mAh / g, or any range of two of the above values, such as 345mAh / g~360mAh / g, 350mAh / g~380mAh / g, or 370mAh / g~400mAh / g, etc.

[0099] By adjusting the specific capacity of the negative electrode active material to the range of 345 mAh / g to 400 mAh / g, it can be matched with the positive electrode active material provided in this application, thereby improving the energy density of lithium-ion batteries.

[0100] In some embodiments, in addition to the aforementioned artificial graphite, the negative electrode active material may also include other negative electrode active materials to regulate the battery performance of the lithium-ion battery. For example, the other negative electrode active materials may be at least one of silicon-based negative electrode active materials and titanium-based negative electrode active materials.

[0101] In some embodiments, the negative electrode film layer may further include one or more of a negative electrode binder, a negative electrode conductive agent, and other optional additives. In some embodiments, the negative electrode binder may be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), lithium-ionized polyacrylic acid (PAALi), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). In some embodiments, the negative electrode conductive agent may be one or more of superconducting carbon, carbon black (for example, it may include one or more of acetylene black, Ketjen black, and Super P), carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, other optional additives may be thickeners and dispersants (e.g., carboxymethyl cellulose CMC) and PTC thermistor materials.

[0102] In some embodiments, the material of the separator can be selected from one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer can be the same or different.

[0103] It should be noted that the various parameters of the positive or negative active materials provided in the embodiments of this application can be obtained by sampling and testing from the cold-pressed positive or negative film layer.

[0104] The embodiments of this application improve the energy density and cycle life of lithium-ion batteries by controlling the specific composition of the positive electrode active material and the specific capacity of the negative electrode active material.

[0105] In some embodiments, layered lithium-containing transition metal oxides include Li a Ni b Co c M d O e A f Wherein, 0<a≤1.2, 0.50≤b≤0.75, 0.05≤c≤0.20, 0.05≤d≤0.45, b+c+d=1; 1≤e≤2; 0≤f≤1, e+f=2; M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, W, Nb, Sb and B, and A includes one or more of N, F, S and Cl.

[0106] As an example, layered lithium-containing transition metal oxides may include, but are not limited to, LiNi. 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.5 Co 0.2 Al 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.7 Co 0.15 Mn 0.15 O2, LiNi 0.75 Co 0.05 Mn 0.2 O2, LiNi 0.5 Co 0.05 Mn 0.45 One or more of O2.

[0107] The embodiments of this application, through the layered lithium-containing transition metal oxide of the above-described general chemical formula, can improve the structural stability of the layered lithium-containing transition metal oxide while maintaining a high energy density in lithium-ion batteries, thereby enabling lithium-ion batteries to have good cycle life.

[0108] In some embodiments, the nickel-cobalt compound includes nickel-cobalt compounds with a single crystal morphology.

[0109] A single crystal refers to a single primary particle. In some embodiments, a single crystal also includes a quasi-single crystal, which refers to a particle formed by the aggregation of a small number (e.g., 2 to 10) of primary particles. Whether a nickel-cobalt compound has a single-crystal morphology can be determined by scanning electron microscopy or transmission electron microscopy.

[0110] In some embodiments, the positive electrode active material may include a nickel-cobalt compound with a single-crystal morphology, and may also include a nickel-cobalt compound with a polycrystalline morphology. Polycrystalline refers to secondary particles formed by the aggregation of multiple (e.g., 11 or more) primary particles.

[0111] Compared to polycrystalline nickel-cobalt compounds, single-crystal nickel-cobalt compounds have fewer grain boundary defects, higher structural stability, and fewer side reactions in the battery, thus having a positive impact on the cycle life of lithium-ion batteries.

[0112] The embodiments of this application improve the cycle life of lithium-ion batteries by using positive electrode active materials containing nickel-cobalt compounds with single-crystal morphology.

[0113] In some embodiments, the Dv50 of the positive electrode active material is in the range of 2.5µm to 5.5µm.

[0114] The average volumetric particle size Dv50 of the positive electrode active material refers to the median particle size of the positive electrode active material, indicating that 50% of the particles by volume have a diameter greater than this value, and another 50% of the particles by volume have a diameter smaller than this value. The average volumetric particle size Dv50 of the embodiments in this application can be referenced to standard GB / T 19077.1. In 2016, particle size was determined using a laser particle size analyzer (such as Malvern Master Size 3000).

[0115] The Dv50 of the positive electrode active material can be 2.5µm, 2.8µm, 3µm, 3.2µm, 3.5µm, 3.8µm, 4µm, 4.2µm, 4.5µm, 4.8µm, 5µm, 5.2µm, 5.5µm, or any range of two of the above values, such as 2.5µm~3.5µm, 3µm~4µm, 3.5µm~4.5µm, 4µm~5µm, or 4.5µm~5.5µm.

[0116] The embodiments of this application utilize positive electrode active materials with an average volume particle size Dv50 within the aforementioned range, enabling lithium-ion batteries to possess high energy density and cycle life.

[0117] In some embodiments, the specific capacity of the positive electrode active material is in the range of 185 mAh / g to 210 mAh / g. The specific capacity of the positive electrode active material can be 185 mAh / g, 190 mAh / g, 195 mAh / g, 200 mAh / g, 205 mAh / g, 210 mAh / g, etc., or a range consisting of any two of the above values, such as 185 mAh / g to 200 mAh / g, 190 mAh / g to 205 mAh / g, or 200 mAh / g to 210 mAh / g, etc.

[0118] The specific capacity of positive electrode active material refers to the ratio of the electrical capacity that the positive electrode active material inside a lithium-ion battery can release to the mass of the positive electrode active material. It is an important indicator for measuring the energy storage capacity of positive electrode materials in lithium-ion batteries, and is usually expressed in milliampere-hours per gram (mAh / g).

[0119] The specific capacity of the positive electrode active material can be tested using any known method. As an example, a method for testing the specific capacity of the positive electrode active material may include: using an ARE-310 mixer to mix the active material, PVDF, and conductive carbon black in a mass ratio of 90:5:5, with NMP as the solvent, to form a positive electrode slurry, which is then coated onto aluminum foil at a certain areal density. The slurry is dried at 100°C for 2 hours in an airflow drying oven, compacted to a certain density using a press, and cut into 14mm diameter discs. Before assembling the battery, the discs are dried in a vacuum drying oven at 105°C for 4 hours under a negative pressure of -0.09MPa. A coin cell is assembled in a glove box, using a lithium sheet as the negative electrode, a PE separator, and 110μL of electrolyte (lithium hexafluorophosphate as the lithium salt, a mixture of ethyl methyl carbonate and ethylene carbonate in a 1:1 volume ratio, with a lithium salt concentration of 1M) is injected. Cycle at 0.1C / 0.1C for 3 cycles at 2.5~4.4V, and use the discharge capacity of the last cycle as the specific capacity of the positive electrode active material.

[0120] The embodiments of this application improve the energy density of lithium-ion batteries by using positive electrode active materials within the above-mentioned specific capacity range.

[0121] In some embodiments, the mass percentage of the nickel-cobalt compound is greater than or equal to 80% based on the total mass of the positive electrode active material. The mass percentage of the nickel-cobalt compound, based on the total mass of the positive electrode active material, can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or a range of any two of the above values, such as 80%~90%, 85%~95%, or 90%~100%.

[0122] The embodiments of this application improve the energy density of lithium-ion batteries by adjusting the mass ratio of nickel-cobalt element compounds based on the total mass of the positive electrode active material.

[0123] In some embodiments, the compaction density of the positive electrode film is in the range of 3.1 g / cc to 3.6 g / cc.

[0124] The compaction density of the positive electrode film refers to the weight per unit volume of the material forming the positive electrode film on the positive electrode current collector after compaction treatment, usually expressed in g / cc (grams per cubic centimeter). The compaction density of the positive electrode film reflects the degree of compaction of the material forming the positive electrode film. The compaction density of the positive electrode film can be tested using equipment and methods known in the art. The compaction density of the positive electrode film is equal to the ratio of the coating weight of the positive electrode film to the thickness of the positive electrode film. The coating weight of the positive electrode film refers to the weight per unit area of ​​the material forming the positive electrode film on the positive electrode current collector, and can be expressed as mg / 1540.25mm². 2 The weight of the positive electrode coating is measured in milligrams per 1540.25 square millimeters. The coating weight can be tested using equipment and methods known in the art, for example, by taking a single-sided coated and cold-pressed positive electrode sheet (if it is a double-sided coated positive electrode sheet, the coating on one side can be wiped off first), and cutting it into pieces with an area of ​​1540.25 mm². 2 Take the small circular electrode and weigh it; then wipe off the positive electrode film layer of the weighed positive electrode sheet and weigh the positive current collector. The coating weight of the positive electrode film layer is equal to the weight of the small circular electrode sheet minus the weight of the positive current collector.

[0125] The embodiments of this application improve the energy density of lithium-ion batteries by using positive electrode film layers within the aforementioned compaction density range.

[0126] In some embodiments, the coating weight of the positive electrode film is 160 mg / 1540.25 mm. 2 ~270mg / 1540.25mm 2 Within this range. The coating weight of the positive electrode film can be 160mg / 1540.25mm. 2 170mg / 1540.25mm 2 180mg / 1540.25mm 2 190mg / 1540.25mm 2 200mg / 1540.25mm 2 210mg / 1540.25mm 2 220mg / 1540.25mm 2 230mg / 1540.25mm 2 240mg / 1540.25mm 2250mg / 1540.25mm 2 260mg / 1540.25mm 2 270mg / 1540.25mm 2 etc., or a range consisting of any two of the above values, for example, 160mg / 1540.25mm. 2 ~180mg / 1540.25mm 2 170mg / 1540.25mm 2 ~190mg / 1540.25mm 2 190mg / 1540.25mm 2 ~210mg / 1540.25mm 2 200mg / 1540.25mm 2 ~220mg / 1540.25mm 2 210mg / 1540.25mm 2 ~230mg / 1540.25mm 2 220mg / 1540.25mm 2 ~240mg / 1540.25mm 2 230mg / 1540.25mm 2 ~250mg / 1540.25mm 2 240mg / 1540.25mm 2 ~260mg / 1540.25mm 2 Or 250mg / 1540.25mm 2 ~270mg / 1540.25mm 2 wait.

[0127] The embodiments of this application improve the energy density of lithium-ion batteries by employing positive electrode film layers within the above-described coating weight range.

[0128] In some embodiments, the mass percentage of artificial graphite, based on the total mass of the negative electrode film, is in the range of 70% to 98.5%. The mass percentage of artificial graphite, based on the total mass of the negative electrode film, can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 98.5%, etc., or a range consisting of any two of the above values, for example, 70%~80%, 80%~90%, 85%~95%, or 90%~98.5%, etc.

[0129] The embodiments of this application improve the cycle life of lithium-ion batteries by using artificial graphite within the above-mentioned mass percentage range.

[0130] In some embodiments, the negative electrode active material also includes amorphous carbon.

[0131] Amorphous carbon refers to a transitional state of carbon, generally referring to carbon elements other than graphite and diamond. In some embodiments, amorphous carbon includes one or both of hard carbon and soft carbon.

[0132] The embodiments of this application regulate the battery performance of lithium-ion batteries by using anode active materials including amorphous carbon.

[0133] In some embodiments, based on the total mass of the negative electrode film, the mass percentage of amorphous carbon is less than or equal to 9.85%, and the mass percentage of artificial graphite is in the range of 72% to 98.5%. Based on the total mass of the negative electrode film, the mass percentage of amorphous carbon can be 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 9.5%, 9.85%, etc., or a range consisting of any two of the above values, for example, 0.01% to 1%, 0.5% to 1.5%, 1% to 5%, 3% to 8%, or 5% to 9.85%, etc. Based on the total mass of the negative electrode film, the mass percentage of artificial graphite can be 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 98.5%, etc., or a range of any two of the above values, for example, 72%~82%, 80%~90%, 85%~95%, or 90%~98.5%, etc.

[0134] The embodiments of this application, through the above-mentioned mass ratio of amorphous carbon and artificial graphite, enable lithium-ion batteries to still have good cycle life while controlling the battery performance.

[0135] In some embodiments, at least a portion of the surface of the artificial graphite is covered with amorphous carbon.

[0136] The presence of at least a portion of the surface of the artificial graphite in this application covered with amorphous carbon can be tested using equipment and methods known in the art. As an example, the specific morphology of the negative electrode active material can be observed using a transmission electron microscope.

[0137] The embodiments of this application improve the charging performance of lithium-ion batteries by using artificial graphite with at least a portion of its surface covered with amorphous carbon.

[0138] In some embodiments, the initial coulombic efficiency of the negative electrode active material is greater than or equal to 92%.

[0139] The initial coulombic efficiency of the negative electrode active material can be tested using equipment and methods known in the art. For example, the aforementioned negative electrode active material is mixed uniformly with conductive carbon black (conductive agent) and polyacrylic acid (binder) at a mass ratio of 8:1:1, then added to deionized water as a solvent, and stirred under the action of a high-speed stirrer until the system is homogeneous, obtaining a negative electrode slurry with a solid content of 45%. The negative electrode slurry is uniformly coated onto a copper foil (negative electrode current collector), dried at 85°C, and cold-pressed to obtain a negative electrode sheet. Using a lithium metal sheet as the counter electrode, a Celgard 2400 separator is used, and an electrolyte (lithium hexafluorophosphate as lithium salt, a mixture of ethyl methyl carbonate and ethylene carbonate in a 1:1 volume ratio, with a lithium salt concentration of 1M) is injected to assemble a coin cell. After the coin cell was left to stand for 4 hours, it was discharged at a constant current of 0.05C to 5mV. After standing for 10 minutes, it was discharged at a constant current of 50μA to 5mV, and the total discharge capacity of the coin cell was recorded. Then, after the coin cell was left to stand for 10 minutes, it was charged at a constant current of 0.1C to 2.0V, and the charging capacity of the coin cell was recorded. The initial coulombic efficiency of the negative electrode active material = charging capacity / total discharge capacity.

[0140] The embodiments of this application improve the cycle life of lithium-ion batteries by using negative electrode active materials within the first coulombic efficiency range described above.

[0141] In some embodiments, the compaction density of the negative electrode film layer is in the range of 1.5 g / cc to 1.8 g / cc. The compaction density of the negative electrode film layer can be 1.5 g / cc, 1.55 g / cc, 1.6 g / cc, 1.65 g / cc, 1.7 g / cc, 1.75 g / cc, 1.8 g / cc, etc., or a range consisting of any two of the above values, for example, it can be 1.5 g / cc to 1.7 g / cc or 1.6 g / cc to 1.8 g / cc, etc.

[0142] The compaction density of the negative electrode film refers to the weight per unit volume of the material forming the negative electrode film on the negative electrode current collector after compaction treatment, usually expressed in g / cc (grams per cubic centimeter). The compaction density reflects the degree of compaction of the material forming the negative electrode film. The compaction density of the negative electrode film can be tested using equipment and methods known in the art. The compaction density of the negative electrode film is equal to the ratio of the coating weight of the negative electrode film to the thickness of the negative electrode film. The coating weight of the negative electrode film refers to the weight of the material forming the negative electrode film per unit area coated on the negative electrode current collector, and can be expressed as mg / 1540.25mm². 2The weight of the negative electrode coating is measured in milligrams per 1540.25 mm². The coating weight can be tested using equipment and methods known in the art, for example, by taking a single-sided coated negative electrode sheet that has been cold-pressed (if it is a double-sided coated negative electrode sheet, the negative electrode film on one side can be wiped off first), and cutting it into pieces with an area of ​​1540.25 mm². 2 Take the small disc and weigh it; then wipe off the negative electrode film layer of the weighed negative electrode sheet and weigh the negative electrode current collector. The coating weight of the negative electrode film layer is equal to the weight of the small disc minus the weight of the negative electrode current collector.

[0143] The embodiments of this application improve the energy density of lithium-ion batteries by using negative electrode film layers within the aforementioned compaction density range.

[0144] In some embodiments, the coating weight of the negative electrode film is 100 mg / 1540.25 mm. 2 ~190mg / 1540.25mm 2 Within this range. The coating weight of the negative electrode film can be 100mg / 1540.25mm. 2 105mg / 1540.25mm 2 110mg / 1540.25mm 2 115mg / 1540.25mm 2 120mg / 1540.25mm 2 125mg / 1540.25mm 2 130mg / 1540.25mm 2 135mg / 1540.25mm 2 140mg / 1540.25mm 2 145mg / 1540.25mm 2 150mg / 1540.25mm 2 155mg / 1540.25mm 2 160mg / 1540.25mm 2 165mg / 1540.25mm 2 170mg / 1540.25mm 2 175mg / 1540.25mm 2 180mg / 1540.25mm 2 185mg / 1540.25mm 2 190mg / 1540.25mm 2 etc., or a range consisting of any two of the above values, for example, 100mg / 1540.25mm. 2 ~130mg / 1540.25mm2 120mg / 1540.25mm 2 ~160mg / 1540.25mm 2 Or 150mg / 1540.25mm 2 ~190mg / 1540.25mm 2 wait.

[0145] The embodiments of this application improve the energy density of lithium-ion batteries by employing negative electrode film layers within the above-described coating weight range.

[0146] In some embodiments, the negative electrode film layer includes a first negative electrode sub-film layer and a second negative electrode sub-film layer, the second negative electrode sub-film layer being disposed between the first negative electrode sub-film layer and the negative electrode current collector. The first negative electrode sub-film layer includes a first negative electrode active material, which includes amorphous carbon and artificial graphite. The second negative electrode sub-film layer includes a second negative electrode active material, which includes artificial graphite or amorphous carbon and artificial graphite; the specific capacity of the first negative electrode active material is in the range of 345 mAh / g to 395 mAh / g, and the specific capacity of the second negative electrode active material is in the range of 350 mAh / g to 400 mAh / g.

[0147] The specific capacity of the first negative electrode active material can be 345mAh / g, 350mAh / g, 355mAh / g, 360mAh / g, 365mAh / g, 370mAh / g, 375mAh / g, 380mAh / g, 385mAh / g, 390mAh / g, 395mAh / g, etc., or a range of any two of the above values, such as 345mAh / g~360mAh / g, 350mAh / g~380mAh / g, or 370mAh / g~395mAh / g, etc.

[0148] The specific capacity of the second negative electrode active material can be 350mAh / g, 355mAh / g, 360mAh / g, 365mAh / g, 370mAh / g, 375mAh / g, 380mAh / g, 385mAh / g, 390mAh / g, 395mAh / g, 400mAh / g, or any range of two of the above values, such as 350mAh / g~370mAh / g, 360mAh / g~380mAh / g, or 370mAh / g~400mAh / g, etc.

[0149] Among the first and second negative electrode active materials, the second negative electrode active material has a larger specific capacity, contributing more to the energy density of the lithium-ion battery, while the first negative electrode active material has a smaller specific capacity, contributing more to the regulation of the battery performance of the lithium-ion battery.

[0150] The embodiments of this application, by layering the negative electrode film and differentially controlling the specific capacity of each layer of negative electrode active material, still maintain good energy density while controlling the battery performance of lithium-ion batteries.

[0151] In some embodiments, based on the total mass of the first negative electrode film layer, the mass percentage of amorphous carbon in the first negative electrode film layer is in the range of 0.1% to 9.85%; based on the total mass of the second negative electrode film layer, the mass percentage of amorphous carbon in the second negative electrode film layer is in the range of 0% to 9.5%.

[0152] Based on the total mass of the first anode film layer, the mass percentage of amorphous carbon in the first anode film layer can be 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 9.5%, 9.85%, etc., or a range consisting of any two of the above values, for example, 0.1%~1%, 0.5%~1.5%, 1%~5%, 3%~8%, or 5%~9.85%, etc. Based on the total mass of the second anode film layer, the mass percentage of amorphous carbon in the second anode film layer can be 0, 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 9.5%, etc., or a range consisting of any two of the above values, for example, 0.1%~1%, 0.5%~1.5%, 1%~5%, 3%~8%, or 5%~9.5%, etc.

[0153] Among them, in the first negative electrode film layer and the second negative electrode film layer, the mass proportion of amorphous carbon in the first negative electrode film layer is relatively large, the number of sites for intercalation and deintercalation of active ions in the first negative electrode active material is relatively large, and the diffusion rate of active ions in the particles of the first negative electrode active material is relatively large. In the second negative electrode film layer, the mass proportion of amorphous carbon is relatively small, the surface defects of the second negative electrode active material are relatively few, the structural stability is relatively good, and the cycle life is relatively high.

[0154] The embodiments of this application achieve good energy density while controlling the battery performance of lithium-ion batteries by adjusting the mass ratio of amorphous carbon in each layer of the negative electrode film.

[0155] In some embodiments, the Dv50 of the first negative electrode active material is less than the Dv50 of the second negative electrode active material.

[0156] Among the first and second anode active materials, the first anode active material has a smaller Dv50 and a larger porosity in the first anode sub-film layer, which is beneficial for lithium-ion transport. The second anode active material has a larger Dv50 and a smaller porosity in the second anode sub-film layer, which is beneficial for improving energy density.

[0157] The embodiments of this application, through the first and second negative electrode active materials within the Dv50 range described above, still exhibit good energy density while regulating the battery performance of lithium-ion batteries.

[0158] In some embodiments, the Dv50 of the first negative electrode active material is in the range of 8.5µm to 15.5µm. The Dv50 of the first negative electrode active material can be 8.5µm, 8.6µm, 8.7µm, 8.8µm, 8.9µm, 9.0µm, 9.1µm, 9.2µm, 9.3µm, 9.4µm, 9.5µm, 9.6µm, 9.7µm, 9.8µm, 9.9µm, 10.0µm, 10.1µm, 10.2µm, 10.3µm, or 10.4µm. , 10.5µm, 10.6µm, 10.7µm, 10.8µm, 10.9µm, 11.0µm, 11.1µm, 11.2µm, 11.3µm, 11.4µm , 11.5µm, 11.6µm, 11.7µm, 11.8µm, 11.9µm, 12.0µm, 12.1µm, 12.2µm, 12.3µm, 12.4µm , 12.5µm, 12.6µm, 12.7µm, 12.8µm, 12.9µm, 13.0µm, 13.1µm, 13.2µm, 13.3µm, 13.4µm , 13.5µm, 13.6µm, 13.7µm, 13.8µm, 13.9µm, 14.0µm, 14.1µm, 14.2µm, 14.3µm, 14.4µm 14.5µm, 14.6µm, 14.7µm, 14.8µm, 14.9µm, 15.0µm, 15.1µm, 15.2µm, 15.3µm, 15.4µm, 15.5µm, etc., or any range of two of the above values, such as 8.5µm~12.5µm, 10.5µm~14.5µm, or 12.5µm~15.5µm, etc.

[0159] In some embodiments, the Dv50 of the second negative electrode active material is in the range of 11µm to 20µm. The Dv50 of the second negative electrode active material can be 11.0µm, 11.1µm, 11.2µm, 11.3µm, 11.4µm, 11.5µm, 11.6µm, 11.7µm, 11.8µm, 11.9µm, 12.0µm, 12.1µm, 12.2µm, 12.3µm, 12.4µm, 12.5µm, 12.6µm, 12.7µm, 12.8µm, 12.9µm, 13.0µm, 13.1µm, or 13.2µm. , 13.3µm, 13.4µm, 13.5µm, 13.6µm, 13.7µm, 13.8µm, 13.9µm, 14.0µm, 14.1µm, 14.2µm, 14.3µm, 14.4µm, 14. 5µm, 14.6µm, 14.7µm, 14.8µm, 14.9µm, 15.0µm, 15.1µm, 15.2µm, 15.3µm, 15.4µm, 15.5µm, 15.6µm, 15.7µm, 15.8µm, 15.9µm, 16.0µm, 16.1µm, 16.2µm, 16.3µm, 16.4µm, 16.5µm, 16.6µm, 16.7µm, 16.8µm, 16.9µm, 17.0 µm, 17.1µm, 17.2µm, 17.3µm, 17.4µm, 17.5µm, 17.6µm, 17.7µm, 17.8µm, 17.9µm, 18.0µm, 18.1µm, 18.2µm, 1 8.3µm, 18.4µm, 18.5µm, 18.6µm, 18.7µm, 18.8µm, 18.9µm, 19.0µm, 19.1µm, 19.2µm, 19.3µm, 19.4µm, 19.5µm, 19.6µm, 19.7µm, 19.8µm, 19.9µm, 20.0µm, etc., or any range of two of the above values, such as 11µm~15µm, 13µm~18µm, or 15µm~20µm, etc.

[0160] The embodiments of this application, through the first and second negative electrode active materials within the Dv50 range described above, still exhibit good energy density while regulating the battery performance of lithium-ion batteries.

[0161] In some embodiments, the electrolyte includes a solvent; the solvent includes a first solvent, which includes one or both of carboxylic acid ester solvents and chain carbonate solvents; the weight percentage of the first solvent is less than or equal to 30% based on the total weight of the solvents.

[0162] The first solvent has the advantages of low viscosity and low freezing point, which helps to improve the migration speed of lithium ions and facilitates sufficient and effective contact between the active material and the electrolyte. Adding it to the electrolyte is beneficial for regulating the battery performance of lithium-ion batteries. However, the first solvent is prone to film-forming side reactions with the negative electrode and gas generation during battery cycling, which affects the cycle performance of lithium-ion batteries.

[0163] Carboxylic acid ester solvents are organic solvents containing carboxylic acid ester functional groups. They typically have high conductivity, low surface tension, and low viscosity, which helps to improve the migration speed of lithium ions and facilitates sufficient and effective contact between the active material and the electrolyte.

[0164] Chain carbonate solvents typically have low viscosity, good flowability, and high conductivity, which are beneficial for promoting the rapid transport of lithium ions and improving the charge and discharge performance of batteries.

[0165] The components and their contents of the electrolyte can be determined according to methods known in the art. For example, they can be determined by gas chromatography, gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma optical emission spectrometry (ICP-OES), etc.

[0166] Based on the total weight of the solvent, the weight percentage of the first solvent can be 0%, 0.1%, 0.2%, 0.5%, 1%, 1.1%, 1.2%, 1.5%, 2%, 2.1%, 2.2%, 2.5%, 3%, 3.1%, 3.2%, 3.5%, 4%, 4.1%, 4.2%, 4.5%, 5%, 5.1%, 5.2%, 5.5%, 6%, 6.1%, 6.2%, 6.5%, 7%, 7.1%, 7.2%, 7.5%, 8%, 8.1%, 8.2%, 8.5%, 9%, 9.1%, 9.2%, 9.5%, 10%, 10.1%, 10.2%, 10.5%, 11%, 11.1%, 11.2%, 11.5%, 12%, 12.1%, 12.2%. 12.5%, 13%, 13.1%, 13.2%, 13.5%, 14%, 14.1%, 14.2%, 14.5%, 15%, 15.1%, 15.2%, 15.5%, 16%, 16.1%, 16.2%, 16.5%, 17%, 17.1%, 17.2%, 17.5%, 18%, 18.1%, 18.2%, 18.5%, 19%, 19.1%, 19.2%, 19.5%, 20%, 21%, 22%, 25%, 30%, etc., or any range of any two of the above values, for example, 0%~2%, 1%~5%, 3%~8%, 5%~10%, 8%~15%, 10%~20%, 15%~25%, or 20%~30%, etc.

[0167] The embodiments of this application reduce the occurrence of film-forming side reactions and gas generation between the electrolyte and the negative electrode during battery cycling by adjusting the weight ratio of the first solvent in the electrolyte, thereby improving the film-forming stability of the electrolyte on the negative electrode sheet and enhancing the cycle life of the lithium-ion battery.

[0168] In some embodiments, the carboxylic acid ester solvent includes one or more of the following: γ-butyrolactone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, isobutyl propionate, pentyl propionate, isopentyl propionate, ethyl isopropionate, methyl butyrate, ethyl butyrate, ethyl isobutyrate, butyl butyrate, butyl isobutyrate, pentyl butyrate, isopentyl butyrate, ethyl valerate, ethyl isovalerate, propyl valerate, propyl isovalerate, and compounds in which the carboxylic acid ester solvent is partially or completely substituted.

[0169] The embodiments of this application use carboxylic acid ester solvents within the above-mentioned range. The high conductivity, low surface tension, and low viscosity of carboxylic acid ester solvents enhance the migration speed of lithium ions, facilitate sufficient and effective contact between the active material and the electrolyte, and regulate the battery performance of the lithium-ion battery.

[0170] In some embodiments, the chain carbonate solvent includes one or more of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, dipropyl carbonate, and compounds in which the chain carbonate solvent is partially or completely substituted.

[0171] The embodiments of this application use chain carbonate solvents within the above-mentioned range to regulate the battery performance of lithium-ion batteries.

[0172] In some embodiments, the electrolyte comprises a lithium salt; the concentration of the lithium salt in the electrolyte is between 0.7 mol / L and 1.2 mol / L. The concentration of the lithium salt in the electrolyte can be 0.7 mol / L, 0.71 mol / L, 0.72 mol / L, 0.73 mol / L, 0.74 mol / L, 0.75 mol / L, 0.76 mol / L, 0.77 mol / L, 0.78 mol / L, 0.79 mol / L, 0.8 mol / L, 0.81 mol / L, 0.82 mol / L, 0.83 mol / L, 0.84 mol / L, 0.85 mol / L, 0.86 mol / L, or 0. 87 mol / L, 0.88 mol / L, 0.9 mol / L, 0.91 mol / L, 0.92 mol / L, 0.93 mol / L, 0.94 mol / L, 0.95 mol / L, 0.96 mol / L, 0.97 mol / L, 0.98 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, etc., or any range of two of the above values, such as 0.7 mol / L to 0.9 mol / L, 0.8 mol / L to 1.0 mol / L, or 0.9 mol / L to 1.2 mol / L, etc.

[0173] Lithium salts are compounds containing lithium ions that act as carriers of these ions in the electrolyte, migrating between the positive and negative electrodes. Solvents are used to dissolve the lithium salts, serving as the medium that supports the migration of lithium ions.

[0174] In some embodiments, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0175] The embodiments of this application, by employing lithium salts of the above concentration, are beneficial to improving the film-forming stability of the electrolyte at the negative electrode, regulating the conductivity of the electrolyte, enhancing the migration rate of lithium ions, and improving the cycle life of lithium-ion batteries.

[0176] In some embodiments, the conductivity of the electrolyte is in the range of 7 mS / cm to 13 mS / cm.

[0177] The conductivity of the electrolyte can be 7 mS / cm, 7.1 mS / cm, 7.2 mS / cm, 7.3 mS / cm, 7.4 mS / cm, 7.5 mS / cm, 7.6 mS / cm, 7.7 mS / cm, 7.8 mS / cm, 7.9 mS / cm, 8 mS / cm, 8.1 mS / cm, 8.2 mS / cm, 8.3 mS / cm, 8.4 mS / cm, 8.5 mS / cm, 8.6 mS / cm, 8.7 mS / cm, 8... .8mS / cm, 8.9mS / cm, 9mS / cm, 9.1mS / cm, 9.2mS / cm, 9.3mS / cm, 9.4mS / cm, 9.5mS / cm, 9.6mS / cm, 9.7mS / cm, 9.8mS / cm, 9.9mS / cm, 10mS / cm, 10.1mS / cm, 10.2mS / cm, 10.3mS / cm, 10.4mS / cm, 10.5mS / cm, 10.6mS / cm, 10.7mS / cm, 10.8mS / cm, 10.9mS / cm, 11mS / cm, 11.1mS / cm, 11.2mS / cm, 11.3mS / cm, 11.4mS / cm, 11.5mS / cm, 11.6mS / cm, 11.7mS / cm, 11.8mS / cm, 11.9mS / cm, 12mS / cm, 12.1mS / cm, 12.2mS / cm, 12.3mS / cm 12.4mS / cm, 12.5mS / cm, 12.6mS / cm, 12.7mS / cm, 12.8mS / cm, 12.9mS / cm, 13mS / cm, etc., or any range of two of the above values, such as 7mS / cm~9mS / cm, 8mS / cm~10mS / cm, 9mS / cm~11mS / cm, 10mS / cm~12mS / cm, or 11mS / cm~13mS / cm, etc.

[0178] The conductivity of an electrolyte refers to the ability of active ions to conduct within the electrolyte. Higher conductivity indicates greater conductivity of active ions. The conductivity of an electrolyte at 25°C can be tested using any known method. As an example, a possible testing method for an electrolyte includes: heating the test sample and standard liquid to 25°C (±0.1°C); calibrating the testing instrument (Leici DDSJ-308F) using two standard liquids at an ambient temperature of 25°C (±0.5°C); after calibration and cleaning the electrodes, vertically immersing the test sample electrode in the test liquid to begin the test; and recording the test results after the data has stabilized for at least 10 seconds.

[0179] The embodiments of this application improve the transport capability of lithium ions in the electrolyte and regulate the battery performance of lithium-ion batteries by using electrolytes within the above-mentioned conductivity range.

[0180] In some embodiments, the electrolyte injection coefficient is in the range of 2.0 g / Ah to 2.8 g / Ah. The electrolyte injection coefficient can be 2.0 g / Ah, 2.1 g / Ah, 2.2 g / Ah, 2.3 g / Ah, 2.4 g / Ah, 2.5 g / Ah, 2.6 g / Ah, 2.7 g / Ah, 2.8 g / Ah, etc., or a range consisting of any two of the above values, for example, 2.0 g / Ah to 2.5 g / Ah, 2.2 g / Ah to 2.6 g / Ah, or 2.5 g / Ah to 2.8 g / Ah, etc.

[0181] The electrolyte injection coefficient is the ratio of the amount of electrolyte injected to the battery's rated capacity. The battery's rated capacity refers to the amount of electricity the battery can discharge to its cutoff voltage under specified charge and discharge conditions.

[0182] The embodiments of this application improve the uniformity of electrolyte distribution inside the lithium-ion battery by using electrolytes within the above-mentioned electrolyte injection coefficient range, improve the film formation stability of electrolytes on the negative electrode sheet, and enhance the cycle life of the lithium-ion battery.

[0183] Secondly, embodiments of this application provide an electrical device including any of the lithium-ion batteries provided in the first aspect.

[0184] The electrical devices provided by the embodiments of this application have at least the same advantages as lithium-ion batteries, which can improve the battery life of the electrical devices.

[0185] The beneficial effects of this application are further illustrated below with reference to the embodiments.

[0186] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0187] Example 1

[0188] The preparation of a lithium-ion battery includes the following steps:

[0189] (1) Providing the positive electrode: The positive electrode active material LiNi 0.65 Co 0.12 Mn 0.23O2 (specific capacity 197 mAh / g, Dv50 3.5µm): PVDF (polyvinylidene fluoride): conductive carbon black were mixed in a mass ratio of 90:5:5, then a solvent (N-methylpyrrolidone) was added. After thorough mixing, the mixture was coated onto aluminum foil, dried, and cold-pressed to obtain the positive electrode sheet. The coating weight of the positive electrode film was 210 mg / 1540.25 mm. 2 The compacted density is 3.4 g / cc.

[0190] (2) Providing the negative electrode sheet: The negative electrode active material (artificial graphite, specific capacity 358mAh / g), conductive agent (conductive carbon black), binder (styrene-butadiene rubber, SBR), and thickener (carboxymethyl cellulose, CMC) are mixed evenly in a solvent (deionized water) at a weight ratio of 97:0.6:1.25:1.15. The mixture is then coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet. The coating weight of the negative electrode film is 138mg / 1540.25mm. 2 The compaction density is 1.65 g / cc.

[0191] (3) Provide a separation membrane: A 1µm thick Al2O3 coating is applied to two opposite surfaces of a 7µm polyethylene film to form a separation membrane.

[0192] (4) Provide electrolyte: Mix ethyl methyl carbonate (EMC) and ethylene carbonate (EC) in a volume ratio of 3:7, and dissolve LiPF6 (lithium hexafluorophosphate) in the above solvent to obtain an electrolyte with a lithium salt concentration of 1M and a conductivity of 8.7 mS / cm.

[0193] (5) The positive electrode, negative electrode, and two separators are placed in the order of "separator-negative electrode-separator-positive electrode". One end of the positive electrode, negative electrode, and two separators is fixed to the discharge roller, and the other end is stacked together and fixed to the winding shaft. The winding shaft is rotated by a motor to wind the positive electrode, negative electrode, and two separators to obtain a dry cell. The dry cell is subjected to one liquid injection, high-temperature standing, formation, second liquid injection, and high-temperature standing. The liquid injection coefficient is 2.5 g / Ah to obtain a lithium-ion battery.

[0194] The steps for preparing lithium-ion batteries in Examples 2 to 4 are similar to those in Example 1. The difference is that the positive electrode active material in step (1) of Examples 2 to 4 is different from that in Example 1.

[0195] The steps for preparing the lithium-ion battery in Example 5 are similar to those in Example 1. The difference is that the negative electrode active material in step (2) of Example 5 is different from that in Example 1.

[0196] The steps for preparing the lithium-ion battery in Example 6 are similar to those in Example 1. The difference is that in step (2) of Example 6, the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer, and the second negative electrode film layer is disposed between the first negative electrode film layer and the negative electrode current collector; the first negative electrode film layer includes a first negative electrode active material, which includes amorphous carbon and artificial graphite; the second negative electrode film layer includes a second negative electrode active material, which includes artificial graphite.

[0197] The steps for preparing the lithium-ion battery in Example 7 are similar to those in Example 1. The difference is that the electrolyte scheme in step (4) of Example 7 is different from that in Example 1. Specifically, the electrolyte scheme in step (4) of Example 8 is as follows: ethyl methyl carbonate and ethylene carbonate are mixed at a volume ratio of 2:8, and LiPF6 (lithium hexafluorophosphate) is dissolved in the above solvent to obtain an electrolyte with a lithium salt concentration of 1M and a conductivity of 8.3 mS / cm.

[0198] The steps for preparing the lithium-ion battery in Comparative Example 1 are similar to those in Example 1, except that the positive electrode active material in step (1) of Comparative Example 1 is different from that in Example 1.

[0199] The cycle life and energy density of the lithium-ion batteries prepared in Examples 1 to 7 and Comparative Example 1 were tested. The test results are shown in Table 1.

[0200] (1) Cyclic performance test:

[0201] The prepared lithium-ion battery was charged at 25°C with a constant current of 1C to the charging cutoff voltage of 4.4V, then charged with a constant voltage to a current of 0.05C, allowed to stand for 5 minutes, and then discharged at a constant current of 0.33C to the discharge cutoff voltage of 2.5V. Its actual capacity was recorded as C0. Then, it was discharged at a rate of 1C followed by a discharge at 0.33C, and the discharge capacity C of each cycle was recorded. n Until the battery's capacity retention rate reaches 80%, the capacity retention rate = C n / C0*100%, records the number of cycles at this point. The more cycles, the better the cycle performance of the secondary battery.

[0202] (2) Energy density test:

[0203] The lithium-ion batteries prepared in each embodiment and comparative example were placed at 25°C and charged to 4.4V with a constant current of 0.33C, allowed to stand for 1 minute, and then charged to 0.05C with a constant voltage of 4.4V, allowed to stand for 30 minutes. They were then discharged to 2.5V with a constant current of 0.33C, and the discharge capacity A0 was recorded at this point, in Ah. The length, width, and height of the outer surface of the lithium-ion battery were measured using calipers, and the volume of a single cell V0 was calculated, in L. The volumetric energy density of the lithium-ion battery, VED, is calculated as (A0 × discharge plateau voltage of the lithium-ion battery) / V0, in Wh / L. It should be understood that the discharge plateau voltage of lithium-ion batteries with different positive and negative electrode systems varies, and can be obtained by testing their charge-discharge curves or referring to existing literature. It should be noted that the energy density values ​​of some embodiments and / or comparative examples are rounded to show the same value.

[0204] [Amended according to Rule 26, December 16, 2025] Table 1 shows the performance test results of the lithium-ion batteries in each embodiment and comparative example.

[0205] [Revised according to Rule 26, December 16, 2025]

[0206] As can be seen from Table 1:

[0207] Analysis of Examples 1 to 7 and Comparative Example 1: By adjusting the specific composition of the positive electrode active material of the lithium-ion battery and the specific capacity of the negative electrode active material, the lithium-ion batteries of Examples 1 to 7 of this application significantly improve cycle life while ensuring a certain energy density.

[0208] Analysis of Examples 1 to 4: By controlling the specific composition of the positive electrode active material of the lithium-ion battery, the cycle life and energy density fluctuate within a certain range, indicating that controlling the specific composition of the positive electrode active material of the lithium-ion battery has a significant effect on improving cycle life and / or energy density.

[0209] Analysis of Examples 1, 5 and Comparative Example 1: In Example 5, a small amount of amorphous carbon was introduced into the negative electrode film layer. Although the energy density and cycle life of the lithium-ion battery were lower than those of the lithium-ion battery in Example 1, they were significantly improved compared to those of the lithium-ion battery in Comparative Example 1.

[0210] Analysis of Examples 5 and 6: The negative electrode film is arranged in layers. A small amount of amorphous carbon is introduced into the first negative electrode film layer near the electrolyte, and only artificial graphite is used as the active material in the second negative electrode film layer near the negative electrode current collector. Compared with a single-layer negative electrode film layer with a small amount of amorphous carbon introduced, the cycle life and energy density are significantly improved.

[0211] Analysis of Examples 1 and 7: Based on the total mass of the solvent in the electrolyte, the proportion of the first solvent varies, and the cycle life of the lithium-ion battery fluctuates within a certain range, indicating that adjusting the mass proportion of the first solvent in the electrolyte has a significant effect on improving cycle life.

[0212] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between apparatuses or units, and may be electrical, mechanical, or other forms.

[0213] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0214] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A lithium-ion battery, wherein, It includes positive electrode, negative electrode, separator and electrolyte; The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material. The positive electrode active material includes a nickel-cobalt compound, which includes a layered lithium-containing transition metal oxide. The ratio of the molar amount of nickel in the layered lithium-containing transition metal oxide to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide is in the range of 0.50 to 0.75, and the ratio of the molar amount of cobalt in the layered lithium-containing transition metal oxide to the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide is in the range of 0.05 to 0.

20. The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector; the negative electrode film layer includes a negative electrode active material; the negative electrode active material includes artificial graphite; wherein the specific capacity of the negative electrode active material is in the range of 345mAh / g to 400mAh / g.

2. The lithium-ion battery according to claim 1, wherein, The layered lithium-containing transition metal oxide includes Li a Ni b Co c M d O e A f Wherein, 0<a≤1.2, 0.50≤b≤0.75, 0.05≤c≤0.20, 0.05≤d≤0.45, b+c+d=1; 1≤e≤2; 0≤f≤1, e+f=2; M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, W, Nb, Sb and B, and A includes one or more of N, F, S and Cl.

3. The lithium-ion battery according to claim 1 or 2, wherein, The nickel-cobalt compounds include nickel-cobalt compounds with single-crystal morphology.

4. The lithium-ion battery according to any one of claims 1 to 3, wherein, The Dv50 of the positive electrode active material is in the range of 2.5µm to 5.5µm.

5. The lithium-ion battery according to any one of claims 1 to 4, wherein, The specific capacity of the positive electrode active material is in the range of 185 mAh / g to 210 mAh / g.

6. The lithium-ion battery according to any one of claims 1 to 5, wherein, Based on the total mass of the positive electrode active material, the mass percentage of the nickel-cobalt compound is greater than or equal to 80%.

7. The lithium-ion battery according to any one of claims 1 to 6, wherein, The compaction density of the positive electrode film is in the range of 3.1 g / cc to 3.6 g / cc.

8. The lithium-ion battery according to any one of claims 1 to 7, wherein, The coating weight of the positive electrode film is 160 mg / 1540.25 mm. 2 ~270mg / 1540.25mm 2 Within the range.

9. The lithium-ion battery according to any one of claims 1 to 8, wherein, Based on the total mass of the negative electrode film, the mass percentage of the artificial graphite is in the range of 70% to 98.5%.

10. The lithium-ion battery according to any one of claims 1 to 9, wherein, The negative electrode active material also includes amorphous carbon.

11. The lithium-ion battery according to claim 10, wherein, Based on the total mass of the negative electrode film, the mass percentage of amorphous carbon is less than or equal to 9.85%, and the mass percentage of artificial graphite is in the range of 72% to 98.5%.

12. The lithium-ion battery according to claim 10 or 11, wherein, At least a portion of the surface of the artificial graphite is covered with the amorphous carbon.

13. The lithium-ion battery according to any one of claims 1 to 12, wherein, The initial coulombic efficiency of the negative electrode active material is greater than or equal to 92%.

14. The lithium-ion battery according to any one of claims 1 to 13, wherein, The compaction density of the negative electrode film is in the range of 1.5 g / cc to 1.8 g / cc.

15. The lithium-ion battery according to any one of claims 1 to 14, wherein, The coating weight of the negative electrode film is 100 mg / 1540.25 mm. 2 ~190mg / 1540.25mm 2 Within the range.

16. The lithium-ion battery according to any one of claims 1 to 15, wherein, The negative electrode film layer includes a first negative electrode sub-film layer and a second negative electrode sub-film layer, the second negative electrode sub-film layer being disposed between the first negative electrode sub-film layer and the negative electrode current collector; the first negative electrode sub-film layer includes a first negative electrode active material, the first negative electrode active material including amorphous carbon and artificial graphite; the second negative electrode sub-film layer includes a second negative electrode active material, the second negative electrode active material including artificial graphite or the second negative electrode active material including amorphous carbon and artificial graphite; the specific capacity of the first negative electrode active material is in the range of 345mAh / g to 395mAh / g, and the specific capacity of the second negative electrode active material is in the range of 350mAh / g to 400mAh / g.

17. The lithium-ion battery according to claim 16, wherein, Based on the total mass of the first negative electrode film layer, the mass percentage of amorphous carbon in the first negative electrode film layer is in the range of 0.1% to 9.85%; based on the total mass of the second negative electrode film layer, the mass percentage of amorphous carbon in the second negative electrode film layer is in the range of 0% to 9.5%.

18. The lithium-ion battery according to claim 16 or 17, wherein, The Dv50 of the first negative electrode active material is less than the Dv50 of the second negative electrode active material.

19. The lithium-ion battery according to claim 18, wherein, The Dv50 of the first negative electrode active material is in the range of 8.5µm to 15.5µm; the Dv50 of the second negative electrode active material is in the range of 11µm to 20µm.

20. The lithium-ion battery according to any one of claims 1 to 19, wherein, The electrolyte includes a solvent; the solvent includes a first solvent, which includes one or both of carboxylic acid ester solvents and chain carbonate solvents; based on the total weight of the solvents, the weight percentage of the first solvent is less than or equal to 30%.

21. The lithium-ion battery according to claim 20, wherein, The carboxylic acid ester solvents include one or more of the following: γ-butyrolactone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, isobutyl propionate, pentyl propionate, isoamyl propionate, ethyl isopropionate, methyl butyrate, ethyl butyrate, ethyl isobutyrate, butyl butyrate, butyl isobutyrate, pentyl butyrate, isoamyl butyrate, ethyl valerate, ethyl isovalerate, propyl valerate, propyl isovalerate, and compounds in which the carboxylic acid ester solvents are partially or completely substituted.

22. The lithium-ion battery according to claim 20 or 21, wherein, The chain carbonate solvents include one or more of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, dipropyl carbonate, and compounds in which the chain carbonate solvents are partially or completely substituted.

23. The lithium-ion battery according to any one of claims 20 to 22, wherein, The electrolyte includes a lithium salt; the concentration of the lithium salt in the electrolyte is between 0.7 mol / L and 1.2 mol / L.

24. The lithium-ion battery according to any one of claims 20 to 23, wherein, The conductivity of the electrolyte is in the range of 7 mS / cm to 13 mS / cm.

25. The lithium-ion battery according to any one of claims 20 to 24, wherein, The electrolyte injection coefficient is in the range of 2.0 g / Ah to 2.8 g / Ah.

26. An electrical appliance, wherein, Including the lithium-ion battery as described in any one of claims 1 to 25.

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