Positive electrode active materials and their preparation methods, positive electrode sheets, battery cells, batteries and electrical devices

Abstract

This application provides a positive electrode active material and its preparation method, a positive electrode sheet, a battery cell, a battery, and a power device. The positive electrode active material includes Li. 1‑ x Na x Ni a M1 b Co c M2 d Mn e O2; wherein M1 includes Fe, M2 includes Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.1, 0≤e≤0.45, a+b+c+d+e=1. The technical solution of this application can reduce the impact on battery energy density while lowering battery production costs.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a positive electrode active material and its preparation method, a positive electrode sheet, a battery cell, a battery, and an electrical device. Background Technology

[0002] In recent years, the application fields of lithium-ion batteries have become increasingly widespread, including energy storage power sources such as wind power, hydropower, thermal power generation, and solar power plants, as well as electric bicycles, electric motorcycles, military equipment, aerospace, and many other fields. While lithium-ion batteries have achieved tremendous development, higher requirements have been placed on their performance in all aspects.

[0003] Therefore, how to reduce battery production costs without affecting battery performance is an urgent problem to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a positive electrode active material and its preparation method, a positive electrode sheet, a battery cell, a battery, and an electrical device, which can reduce the impact on battery energy density while reducing battery production costs.

[0005] Firstly, a positive electrode active material is provided, including: Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2; wherein M1 includes Fe, M2 includes Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.1, 0≤e≤0.45, a+b+c+d+e=1.

[0006] In the embodiments of this application, the positive electrode active material includes Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2, where M1 includes Fe and M2 includes Al, 0.01≤x≤0.4. Sodium is cheaper than lithium. By replacing some lithium with sodium and controlling the replacement ratio between 1% and 40%, the impact on battery energy density can be reduced while lowering battery production costs.

[0007] In one possible implementation, at a voltage of 4.25V, x and a satisfy: x ≤ 0.67 - 0.6a.

[0008] In this embodiment, 4.25V is Li 1-x Na x Ni a Fe b Co c Al d Mn e The upper limit voltage of O2 can be further guaranteed by ensuring that x and a satisfy x≤0.67-0.6a, i.e., the amount of sodium substitution x, which meets the theoretical requirement.

[0009] In one possible implementation, 0.01 ≤ x ≤ 0.2.

[0010] In one possible implementation, 0.05 ≤ x ≤ 0.15.

[0011] In this embodiment of the application, in order to reduce the production cost of the battery, sodium is used to replace part of the lithium in the positive electrode active material lithium nickel cobalt manganese oxide. Furthermore, by maintaining the replacement ratio at 1%-20%, particularly 5%-15%, a higher energy density of the battery can be maintained while reducing the battery production cost.

[0012] In one possible implementation, b and c satisfy: 0.01≤b+c≤0.3.

[0013] In this embodiment, the content of iron and cobalt elements will affect the power performance of the battery. By ensuring that the sum of b+c satisfies: 0.01≤b+c≤0.3, both the normal energy density and the power of the battery can be guaranteed.

[0014] In one possible implementation, d and e satisfy: 0.01≤d+e≤0.45.

[0015] In this embodiment, the content of aluminum and manganese elements will affect the structural stability of the battery. By ensuring that the sum of d+e satisfies: 0.01≤b+c≤0.45, both the normal energy density of the battery and the structural stability of the battery can be guaranteed.

[0016] A second aspect of this application provides a method for preparing a positive electrode active material, the method comprising: dissolving a lithium source, a sodium source, a nickel source, an iron source, a cobalt source, an aluminum source, and a manganese source in a solution of deionized water containing citric acid to obtain a mixed solution, wherein the mass ratio of the lithium source, the sodium source, the nickel source, the iron source, the cobalt source, the aluminum source, and the manganese source to the mass of the citric acid is 1:1; stirring and drying the mixed solution to obtain a positive electrode active material precursor; and sintering the positive electrode active material precursor to obtain the positive electrode active material; wherein the positive electrode active material includes Li1-x Na x Ni a M1 b Co c M2 d Mn e O2, M1 includes Fe, M2 includes Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.1, 0≤e≤0.45, a+b+c+d+e=1.

[0017] In one possible implementation, the mixed solution is stirred at 60°C until a solid gel is formed; the solid gel is then dried at 100°C for 12 hours and at 400°C for 4 hours, respectively, to obtain the precursor of the positive electrode active material.

[0018] In one possible implementation, the positive electrode active material precursor is calcined at 750°C in an oxygen atmosphere for 20 hours to obtain the positive electrode active material.

[0019] A third aspect of this application provides a positive electrode sheet, comprising: a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector; the positive electrode film layer comprises the positive electrode active material described in any embodiment of the first aspect, or the positive electrode active material prepared by the method for preparing the positive electrode active material described in the second aspect.

[0020] A fourth aspect of this application provides a battery cell including the positive electrode sheet described in the third aspect of this application.

[0021] The fifth aspect of this application provides a battery comprising the battery cell described in the fourth aspect of this application.

[0022] A sixth aspect of this application provides an electrical device including the battery described in the fifth aspect of this application. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced 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.

[0024] Figure 1 This is a flowchart of a method for preparing a positive electrode active material according to an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the structure of the positive electrode sheet according to one embodiment of this application;

[0026] Figure 3 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the structure of a battery cell according to one embodiment of this application;

[0028] Figure 5 This is a schematic diagram of a battery according to one embodiment of this application;

[0029] Figure 6 This is a schematic diagram of the structure of a battery according to one embodiment of this application;

[0030] Figure 7 This is a schematic diagram of the structure of an electrical device according to one embodiment of this application. Detailed Implementation

[0031] The following detailed description, with appropriate reference to the accompanying drawings, outlines embodiments of the positive electrode active material, its preparation method, the positive electrode sheet, the battery cell, the battery, and the power supply device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0034] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0035] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, optionally sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0036] The terms “above,” “below,” “greater than,” or “less than” used in this application include the number itself, such as “at least one” meaning one or more, and “at least one of A and B” meaning “A,” “B,” or “A and B.”

[0037] In the 21st century, humanity faces two severe problems: the energy crisis and environmental pollution. Therefore, the development and research of clean and renewable energy sources are of profound significance. Automobiles account for approximately 40% of oil consumption, and 42% of global air pollution originates from vehicle emissions. Countries worldwide attach great importance to electric vehicles, and my country's 863 Program has also listed their development as a key direction. Research on power batteries, the source of power for vehicles, has become a major bottleneck in the development of electric vehicles. Currently, the main candidates for power batteries are nickel-metal hydride batteries, lithium-ion batteries, and fuel cells. Based on cost-effectiveness considerations, lithium-ion batteries have significant advantages. As an energy storage material, lithium-ion batteries offer advantages over traditional materials, including high voltage, large specific capacity, long cycle life, and good safety performance. They are widely used in portable electronic devices, electric vehicles, aerospace, and military engineering, demonstrating broad application scenarios and significant economic benefits.

[0038] Cathode materials, as a crucial component of lithium-ion batteries, are currently a hot research topic. This is because the performance of the cathode active material largely determines the overall performance of the lithium-ion battery. Currently, ternary materials are considered the preferred material for lithium-ion batteries due to their smaller size, higher energy density, and better safety performance. However, when ternary materials are used as the cathode active material in lithium-ion batteries, how to maintain both high energy density and low production costs, thereby enabling wider application of ternary materials in production, is a pressing technical problem that needs to be solved.

[0039] In view of this, this application provides a positive electrode active material, which includes Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2; wherein M1 includes Fe, M2 includes Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.1, 0≤e≤0.45, a+b+c+d+e=1. By replacing part of the lithium with sodium, the production cost of the battery can be reduced without significantly affecting the battery's energy density.

[0040] The following description, with reference to the accompanying drawings, illustrates the positive electrode active material, its preparation method, the positive electrode sheet, the battery cell, the battery, and the electrical device of this application.

[0041] Furthermore, the technical solution of this application is applicable to various types of batteries such as lithium-ion batteries and lithium metal batteries, and this application does not limit it; for the sake of convenience, lithium-ion batteries will be used as an example for explanation below.

[0042] [Positive electrode active material]

[0043] The first aspect of this application provides a positive electrode active material, which includes: Li 1- x Na x Ni a M1 b Co c M2 d Mn e O2; wherein M1 includes Fe, M2 includes Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.1, 0≤e≤0.45, a+b+c+d+e=1.

[0044] In order to maintain the stability of the structure, some lithium ions need to be retained within the structure when using layered ternary materials such as lithium nickel cobalt manganese oxide. Therefore, this part of the lithium can be replaced with sodium, thereby reducing the cost of lithium nickel cobalt manganese oxide materials.

[0045] The value of 'a' represents the molar content of nickel in the material. When the value of 'a' is greater than 0.7, the positive electrode active material can be called a nickel-rich material (or a high-nickel material). When the value of 'a' is between 0.5 and 0.7, the positive electrode active material can be called a medium-nickel material. Using medium-nickel or high-nickel materials can enable the battery to have a higher energy density.

[0046] b and c represent the molar content of iron and cobalt in the material. Maintaining both within the above range can improve the power capability of the positive electrode active material.

[0047] d and e represent the molar content of aluminum and manganese in the material. Keeping them within the above range can improve the structural stability of the positive electrode active material.

[0048] In the above scheme, the positive electrode active material includes Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2, where M1 includes Fe and M2 includes Al, 0.01≤x≤0.4. Sodium is cheaper than lithium. By replacing some lithium with sodium and controlling the replacement ratio between 1% and 40%, the impact on battery energy density can be reduced while lowering battery production costs.

[0049] Specifically, the value of x can be 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.4 or any value within the above range.

[0050] Specifically, the value of 'a' can be 0.5, 0.55, 0.6, 0.8, 0.9, 0.95, or any value within the above range.

[0051] Specifically, the value of b can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.3 or any value within the above range.

[0052] Specifically, the value of c can be 0, 0.02, 0.05, 0.1, 0.2, 0.3 or any value within the above range.

[0053] Specifically, the value of d can be 0, 0.02, 0.05, 0.08, 0.1 or any value within the above range.

[0054] Specifically, the value of e can be 0.5, 0.9, 1.5, 2.6, 3.8, 4.5 or any value within the above range.

[0055] It should be noted that the values ​​of a, b, c, d, and e can be any values ​​within the above range, but they must satisfy: a + b + c + d + e = 1.

[0056] In some implementations, the positive electrode active material Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2 can also include Li 1-x Na x Ni a M1 b Co c M2 d Mn e O f A g Wherein, A includes at least one of S, N, P, F, Cl, Br or I, 0≤f≤2, 0≤g≤2.

[0057] Specifically, the positive electrode active material includes, but is not limited to, the following substances: Li 0.6 Na 0.4 Ni 0.5 Fe 0.1 Co 0.1 Al 0.05 Mn 0.2 5O2, Li 0.7 Na 0.3 Ni 0.6 Fe 0.05 Co 0.2 Al 0.05 Mn 0.1 O 1.9 S 0.1 .

[0058] It should be noted that in positive electrode sheets, batteries, or electrical devices, lithium ions are consumed during the formation and cycling processes, resulting in a measured total lithium and sodium content of less than 1 in the positive electrode active material. Conversely, if lithium is replenished to the positive electrode sheet, the measured total lithium and sodium content in the positive electrode material will be greater than 1 after the battery undergoes formation and cycling processes.

[0059] Similarly, in the enumeration of positive electrode active materials in this application, the molar content of oxygen is only a theoretical value. The release of oxygen from the crystal lattice will cause the molar content of oxygen to change, and the actual molar content of oxygen will fluctuate.

[0060] In some implementations, at a voltage of 4.25V, x and a satisfy: x ≤ 0.67 - 0.6a.

[0061] The amount of lithium removed from a material varies depending on the voltage. The higher the operating voltage of the battery, the more lithium is removed from the positive electrode active material, and the less lithium remains in the material. By simply replacing the remaining lithium with sodium, costs can be reduced without affecting battery performance.

[0062] After extensive experiments, the applicant fitted the relationship between the initial lithium removal amount 'a' and the lithium removal amount 'y' of the battery as: y = 0.6a + 0.33. The theoretical remaining lithium content is 1 - y, which is 0.67 - 0.6a. Therefore, the remaining lithium content in the material should be 0.67 - 0.6a. Thus, x should theoretically satisfy: x ≤ 0.67 - 0.6a.

[0063] In the above scheme, 4.25V is Li 1-x Na x Ni a Fe b Co c Al d Mn e The upper limit voltage of O2 can be further guaranteed by ensuring that x and a satisfy x≤0.67-0.6a, i.e., the amount of sodium substitution x, which meets the theoretical requirement.

[0064] In some implementations, 0.01 ≤ x ≤ 0.2.

[0065] In some implementations, 0.05 ≤ x ≤ 0.15.

[0066] In the above scheme, to reduce battery production costs, sodium is used to replace some of the lithium in the positive electrode active material, lithium nickel cobalt manganese oxide. Furthermore, by maintaining the replacement ratio at 1%-20%, particularly 5%-15%, a higher energy density of the battery can be maintained while reducing battery production costs.

[0067] In some implementations, b and c satisfy: 0.01≤b+c≤0.3.

[0068] In the above scheme, the content of iron and cobalt elements will affect the power performance of the battery. By ensuring that the sum of b+c satisfies: 0.01≤b+c≤0.3, both the normal energy density and the power of the battery can be guaranteed.

[0069] In some implementations, d and e satisfy: 0.01≤d+e≤0.45.

[0070] In the above scheme, the content of aluminum and manganese elements will affect the structural stability of the battery. By ensuring that the sum of d+e satisfies: 0.01≤b+c≤0.45, both the normal energy density of the battery and the structural stability of the battery can be guaranteed.

[0071] [Preparation method of positive electrode active material]

[0072] The second aspect of this application provides a method for preparing a positive electrode active material. Figure 1 This is a flowchart of a method for preparing a positive electrode active material according to an embodiment of this application, as shown below. Figure 1 As shown, the method 100 includes:

[0073] 101: Dissolve lithium source, sodium source, nickel source, iron source, cobalt source, aluminum source and manganese source in a solution of deionized water containing citric acid to obtain a mixed solution;

[0074] In the above 101 steps, the mass ratio of lithium source, sodium source, nickel source, iron source, cobalt source, aluminum source, and manganese source to the mass of citric acid is 1:1.

[0075] 102: The mixed solution is stirred and dried to obtain the precursor of the positive electrode active material.

[0076] 103: The positive electrode active material is obtained by sintering the precursor of the positive electrode active material.

[0077] Among them, the positive electrode active material includes Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2, M1 includes Fe, M2 includes Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.1, 0≤e≤0.45, a+b+c+d+e=1.

[0078] It should be noted that the sodium source, nickel source, iron source, cobalt source, aluminum source, and manganese source mentioned above can be selected from raw materials known in the art for the preparation of lithium nickel cobalt manganese oxide, and the sodium source can be selected from sodium-containing metal salts known in the art, such as sodium carbonate or sodium hydroxide.

[0079] In some embodiments, the mixed solution is stirred at 60°C until a solid gel is formed; the solid gel is then dried at 100°C for 12 hours and at 400°C for 4 hours, respectively, to obtain a precursor of the positive electrode active material.

[0080] In some embodiments, the positive electrode active material precursor is calcined at 750°C in an oxygen atmosphere for 20 hours to obtain the positive electrode active material.

[0081] In some embodiments, the positive electrode active material may also include positive electrode active materials known in the art for use in batteries. As an example, the positive electrode active material may also include lithium-containing phosphates with an olivine structure. However, this application is not limited to these materials and may also include other conventional materials that can be used as active positive electrode materials in batteries. These positive electrode active materials may be used in combination of two or more. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites.

[0082] [Positive electrode plate]

[0083] A third aspect of this application provides a positive electrode sheet, Figure 2 This is a schematic diagram of the structure of the positive electrode sheet according to one embodiment of this application. Figure 2 As shown, the positive electrode 121 includes a positive current collector 122 and a positive electrode film 123 disposed on at least one side of the positive current collector 122. The positive electrode film 123 includes a positive electrode active material in any embodiment of the first aspect, or a positive electrode active material prepared according to the preparation method of the positive electrode active material described in the second aspect.

[0084] Typically, a battery cell includes a positive electrode 121, a separator, a negative electrode, and an electrolyte. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a ion transporter between the positive and negative electrodes, while the separator, positioned between them, primarily prevents short circuits while allowing ions to pass through.

[0085] It should be noted that the "positive electrode sheet" and "negative electrode sheet" mentioned in the embodiments of this application refer to the whole positive electrode sheet and negative electrode sheet including active materials, current collectors or other additives.

[0086] The positive electrode 121 includes a positive current collector 122 and a positive electrode film 123 disposed on at least one surface of the positive current collector 122, wherein the positive electrode film 123 includes a positive electrode active material.

[0087] As an example, the positive current collector 122 has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer 123 is disposed on either or both of the two opposite surfaces of the positive current collector 122.

[0088] In some embodiments, the positive current collector 122 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 material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0089] In some embodiments, the positive electrode film layer 123 may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0090] In some embodiments, the positive electrode film 123 may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0091] In some embodiments, the positive electrode 121 can be prepared by dispersing the above-mentioned components for preparing the positive electrode, 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 122, and then obtaining the positive electrode 121 after drying, cold pressing and other processes.

[0092] [Negative electrode plate]

[0093] 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 including a negative electrode active material.

[0094] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0095] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0096] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0097] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0098] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0099] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0100] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0101] [Electrolytes]

[0102] The electrolyte acts as a conductor of ions between the positive electrode 121 and the negative electrode. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0103] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0104] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0105] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0106] In some embodiments, the electrolyte may optionally include electrolyte additives. For example, electrolyte additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0107] [Isolation membrane]

[0108] In some embodiments, the battery cell also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0109] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can 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 can be the same or different, without particular limitation.

[0110] In some embodiments, the positive electrode 121, the negative electrode, and the separator can be fabricated into an electrode assembly using a winding process or a stacking process.

[0111] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0112] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0113] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0114] Figure 4 This is a schematic diagram of the structure of a battery cell according to one embodiment of this application. Figure 4 As shown, the outer packaging of the battery cell 200 includes a housing 11 and a cover plate 13. The housing 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be placed over the opening to close the receiving cavity. Positive electrode 121 and negative electrode 121 can be formed into electrode assemblies 12 through a winding process or a stacking process. The electrode assemblies 12 are encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assemblies 12. The battery cell 200 may contain one or more electrode assemblies 12, which can be selected by those skilled in the art according to specific practical needs.

[0115] In some embodiments, the battery cells 200 can also be assembled into a battery module. The number of battery cells 200 contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0116] Figure 5 This is a schematic diagram of a battery according to one embodiment of this application. Figure 6 This is a schematic diagram of the battery structure according to one embodiment of this application. (Refer to...) Figure 5 and Figure 6 The battery 400 may include a battery box and a plurality of battery cells 200 disposed within the battery box. The battery box includes an upper box 401 and a lower box 402, the upper box 401 covering the lower box 402 to form a closed space for accommodating the battery cells 200. The plurality of battery cells 200 may be arranged in any manner within the battery box.

[0117] In addition, this application also provides an electrical device, which includes at least one of the positive electrode 121, battery cell 200, or battery 400 provided in this application. The positive electrode 121, battery cell 200, or battery 400 can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0118] For example, Figure 7 This is a schematic diagram of the structure of an electrical device according to one embodiment of this application. Figure 7 As shown, the electrical device 1 is a vehicle 1, which 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 motor 500, a controller 600, and a battery 400 can be installed inside the vehicle 1. The controller 600 controls the battery 400 to supply power to the motor 500. For example, the battery 400 can be installed at the bottom, front, or rear of the vehicle 1. The battery 400 can be used to power the vehicle 1; for example, it can serve as the operating power source for the vehicle 1's electrical system, such as for the power requirements of starting, navigation, and operation. In another embodiment of this application, the battery 400 can not only serve as the operating power source for the vehicle 1 but also as the driving power source, replacing or partially replacing gasoline or natural gas to provide driving power to the vehicle 1.

[0119] As the electrical device, the positive electrode 121, the battery cell 200, or the battery 400 can be selected according to its usage requirements.

[0120] The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the battery for this electrical device, a 200-cell battery or a 400-cell battery can be used.

[0121] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single 200mAh battery for power.

[0122] [Example]

[0123] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0124] [Example 1]

[0125] 1) Preparation of lithium-ion batteries

[0126] 1.11) Preparation of positive electrode active material: Lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate, and citric acid were dissolved in deionized water in a mass ratio of 35.59g:32.81g:68.38g:74.72g:34.61g:250.12g to form a positive electrode active material solution. The positive electrode active material solution was continuously stirred at 60℃ until a solid gel was formed, and then dried at 100℃ for 12h and at 400℃ for 4h to form a positive electrode active material precursor. The precursor was then calcined at 750℃ in an oxygen atmosphere for 20h to obtain the positive electrode active material Li. 0.6 Na 0.4 Ni 0.5 Co 0.3 Mn 0.2 O2, where x is 0.4, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3, and d+e is 0.2.

[0127] 1.12). Preparation of the positive electrode: The positive electrode active material Li prepared in Example 1 was used... 0.6 Na 0.4 Ni 0.5 Co 0.3 Mn 0.2 O2, conductive carbon nanotubes (CNTs), and positive electrode binder polyvinylidene fluoride (PVDF) are dissolved in N-methylpyrrolidone (NMP) in a weight ratio of 96%:2%:2%. After thorough mixing, a positive electrode slurry is prepared. The positive electrode slurry is coated onto an Al foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0128] 1.2) Preparation of negative electrode sheet: The negative electrode active material artificial graphite, the conductive agent acetylene black, the negative electrode binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) are thoroughly mixed in an appropriate amount of deionized water solvent system at a weight ratio of 96.5%:0.7%:1.8%:1% to obtain a negative electrode slurry. The negative electrode slurry is coated on Cu foil, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0129] 1.3) Preparation of the diaphragm: PE porous polymer film was used as the diaphragm.

[0130] 1.4) Electrolyte: Dissolve EC / EMC / DMC in 1M LiPF6 at a volume ratio of 1:1:1 and stir until homogeneous to obtain a 1mol / L LiPF6 electrolyte.

[0131] 1.5) Assembly: The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide separation. The electrode assembly is then wound up and electrolyte is added. After formation and settling processes, a lithium-ion battery is obtained.

[0132] [Example 2]

[0133] The preparation process of the lithium-ion battery in Example 2 is basically the same as that in Example 1. The difference is that in Example 2, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 46.19g:24.61g:68.38g:74.72g:34.61g:248.51g; where x is 0.3, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3 and d+e is 0.2.

[0134] [Example 3]

[0135] The preparation process of the lithium-ion battery in Example 3 is basically the same as that in Example 1. The difference is that in Example 3, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 52.79g:16.41g:68.38g:74.72g:34.61g:246.91g; where x is 0.2, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3 and d+e is 0.2.

[0136] [Example 4]

[0137] The preparation process of the lithium-ion battery in Example 4 is basically the same as that in Example 1. The difference is that in Example 4, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 65.33g:0.82g:68.38g:74.72g:34.61g:243.86g; where x is 0.01, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3 and d+e is 0.2.

[0138] [Example 5]

[0139] The preparation process of the lithium-ion battery in Example 5 is basically the same as that in Example 1. The difference is that in Example 5, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 62.69g:4.10g:68.38g:74.72g:34.61g:244.5g; where x is 0.05, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3 and d+e is 0.2.

[0140] [Example 6]

[0141] The preparation process of the lithium-ion battery in Example 6 is basically the same as that in Example 1. The difference is that in Example 6, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 56.09g:12.3g:68.38g:74.72g:34.61g:246.11g; where x is 0.15, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3 and d+e is 0.2.

[0142] [Example 7]

[0143] The preparation process of the lithium-ion battery in Example 7 is basically the same as that in Example 1. The difference is that in Example 7, the mass ratio of lithium acetate, sodium acetate, nickel acetate, iron acetate, cobalt acetate, manganese acetate, and citric acid in the positive electrode active material is 56.09g:12.3g:68.38g:19.09g:49.82g:34.61g:240.29g; where x is 0.15, a is 0.5, b is 0.1, c is 0.2, d is 0, e is 0.2, b+c is 0.3, and d+e is 0.2.

[0144] [Example 8]

[0145] The preparation process of the lithium-ion battery in Example 8 is basically the same as that in Example 1. The difference is that in Example 8, the mass ratio of lithium acetate, sodium acetate, nickel acetate, iron acetate, cobalt acetate, aluminum acetate, manganese acetate, and citric acid in the positive electrode active material is 56.09g:12.3g:68.38g:19.09g:49.82g:20.41g:17.3g:243.4g; where x is 0.15, a is 0.5, b is 0.1, c is 0.2, d is 0.1, e is 0.1, b+c is 0.3, and d+e is 0.2.

[0146] [Example 9]

[0147] The preparation process of the lithium-ion battery in Example 9 is basically the same as that in Example 1. The difference is that in Example 9, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 52.79g:16.41g:117.61g:14.94g:13.84g:215.6g; where x is 0.2, a is 0.86, b is 0, c is 0.06, d is 0, e is 0.08, b+c is 0.06 and d+e is 0.08.

[0148] [Example 10]

[0149] The preparation process of the lithium-ion battery in Example 10 is basically the same as that in Example 1. The difference is that in Example 10, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 56.09g:12.3g:117.61g:14.94g:13.84g:214.8g; where x is 0.15, a is 0.86, b is 0, c is 0.06, d is 0, e is 0.08, b+c is 0.06 and d+e is 0.08.

[0150] [Example 11]

[0151] The preparation process of the lithium-ion battery in Example 11 is basically the same as that in Example 1. The difference is that in Example 11, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 59.39g:8.2g:68.38g:74.72g:34.61g:213.99g; where x is 0.1, a is 0.86, b is 0, c is 0.06, d is 0, e is 0.08, b+c is 0.06 and d+e is 0.08.

[0152] [Example 12]

[0153] The preparation process of the lithium-ion battery in Example 12 is basically the same as that in Example 1. The difference is that in Example 12, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 63.35g:3.28g:68.38g:74.72g:34.61g:213.03g; where x is 0.04, a is 0.86, b is 0, c is 0.06, d is 0, e is 0.08, b+c is 0.06 and d+e is 0.08.

[0154] [Example 13]

[0155] The preparation process of the lithium-ion battery in Example 13 is basically the same as that in Example 1. The difference is that in Example 13, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 63.35g:3.28g:134.02g:2.49g:1.73g:204.88g; where x is 0.04, a is 0.98, b is 0, c is 0.01, d is 0, e is 0.01, b+c is 0.01 and d+e is 0.01.

[0156] [Example 14]

[0157] The preparation process of the lithium-ion battery in Example 14 is basically the same as that in Example 1. The difference is that in Example 14, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 60.71g:6.56g:134.02g:2.49g:1.73g:205.52g; where x is 0.08, a is 0.98, b is 0, c is 0.01, d is 0, e is 0.01, b+c is 0.01 and d+e is 0.01.

[0158] [Comparative Example 1]

[0159] The preparation process of the lithium-ion battery in Comparative Example 1 is basically the same as that in Example 1. The difference is that in Comparative Example 1, the mass ratio of lithium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 65.99g:68.38g:74.72g:34.61g:243.7g; where x is 0, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3 and d+e is 0.2.

[0160] [Comparative Example 2]

[0161] The preparation process of the lithium-ion battery in Comparative Example 2 is basically the same as that in Example 1. The difference is that in Example 2, the mass ratio of lithium acetate, sodium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 33g:41.02g:68.38g:74.72g:34.61g:251.72g; where x is 0.5, a is 0.5, b is 0, c is 0.3, d is 0, e is 0.2, b+c is 0.3 and d+e is 0.2.

[0162] [Comparative Example 3]

[0163] The preparation process of the lithium-ion battery in Comparative Example 3 is basically the same as that in Example 1. The difference is that in Comparative Example 3, the mass ratio of lithium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 65.99g:117.61g:14.94g:13.84g:212.39g; where x is 0, a is 0.86, b is 0, c is 0.06, d is 0, e is 0.08, b+c is 0.3 and d+e is 0.08.

[0164] [Comparative Example 4]

[0165] The preparation process of the lithium-ion battery in Comparative Example 4 is basically the same as that in Example 1. The difference is that in Comparative Example 4, the mass ratio of lithium acetate, nickel acetate, cobalt acetate, manganese acetate and citric acid in the positive electrode active material is 65.99g:134.02g:2.49g:1.73g:204.24g; where x is 0, a is 0.98, b is 0, c is 0.01, d is 0, e is 0.01, b+c is 0.01 and d+e is 0.01.

[0166] 2) Physical characterization

[0167] Li 1-x Na x Ni a Fe b Co c Al d Mn e Measurement of the content of each element in O2: After dissolving the positive electrode sheet containing only the active material in hydrogen peroxide solution, the content can be measured by inductively coupled plasma optical emission spectrometry (ICP).

[0168] Table 1. Specific experimental parameters for Examples 1-14 and Comparative Examples 1-4

[0169] Group Positive electrode active material x a b c d e 0.67-0.6a Example 1 <![CDATA[Li 0.6 So 0.4 Ni 0.5 Co 0.3 Mr 0.2 O2]]> 0.4 0.5 0 0.3 0 0.2 0.37 Example 2 <![CDATA[Li 0.7 So 0.3 Ni 0.5 Co 0.3 Mr 0.2 O2]]> 0.3 0.5 0 0.3 0 0.2 0.37 Example 3 <![CDATA[Li 0.8 So 0.2 Ni 0.5 Co 0.3 Mr 0.2 O2]]> 0.2 0.5 0 0.3 0 0.2 0.37 Example 4 <![CDATA[Li 0.99 So 0.01 Ni 0.5 Co 0.3 Mr 0.2 O2]]> 0.01 0.5 0 0.3 0 0.2 0.37 Example 5 <![CDATA[Li 0.95 So 0.05 Ni 0.5 Co 0.3 Mr 0.2 O2]]> 0.05 0.5 0 0.3 0 0.2 0.37 Example 6 <![CDATA[Li 0.85 So 0.15 Ni 0.5 Co 0.3 Mr 0.2 O2]]> 0.15 0.5 0 0.3 0 0.2 0.37 Example 7 <![CDATA[Li 0.85 So 0.15 Ni 0.5 Feb 0.1 Co 0.2 Mr 0.2 O2]]> 0.15 0.5 0.1 0.2 0 0.2 0.37 Example 8 <![CDATA[Li 0.85 So 0.15 Ni 0.5 Feb 0.1 Co 0.2 Al 0.1 Mr 0.1 O2]]> 0.15 0.5 0.1 0.2 0.1 0.1 0.37 Comparative Example 1 <![CDATA[LiNi 0.5 What 0.3 Mn 0.2 O2]]> 0 0.5 0 0.3 0 0.2 / Comparative Example 2 <![CDATA[Li 0.5 So 0.5 Ni 0.5 Co 0.3 Mr 0.2 O2]]> 0.5 0.5 0 0.3 0 0.2 0.37 Example 9 <![CDATA[Li 0.8 So 0.2 Ni 0.86 Co 0.06 Mr 0.08 O2]]> 0.2 0.86 0 0.06 0 0.08 0.15 Example 10 <![CDATA[Li 0.85 So 0.15 Ni 0.86 Co 0.06 Mr 0.08 O2]]> 0.15 0.86 0 0.06 0 0.08 0.15 Example 11 <![CDATA[Li 0.9 So 0.1 Ni 0.86 Co 0.06 Mr 0.08 O2]]> 0.1 0.86 0 0.06 0 0.08 0.15 Example 12 <![CDATA[Li 0.96 So 0.04 Ni 0.86 Co 0.06 Mr 0.08 O2]]> 0.04 0.86 0 0.06 0 0.08 0.15 Comparative Example 3 <![CDATA[LiNi 0.86 What 0.06 Mn 0.08 O2]]> 0 0.86 0 0.06 0 0.08 / Example 13 <![CDATA[Li 0.96 So 0.04 Ni 0.98 Co 0.01 Mr 0.01 O2]]> 0.04 0.98 0 0.01 0 0.01 0.08 Example 14 <![CDATA[Li 0.92 So 0.08 Ni 0.98 Co 0.01 Mr 0.01 O2]]> 0.08 0.98 0 0.01 0 0.01 0.08 Comparative Example 4 <![CDATA[LiNi 0.98 What 0.01 Mn 0.01 O2]]> 0 0.98 0 0.01 0 0.01 /

[0170] 3) Performance Testing

[0171] 3.1) Material cost: The purchase cost of raw materials can be calculated directly. The test results are shown in Table 2.

[0172] 3.2) Testing of the energy density of the positive electrode active material: At room temperature, the lithium-ion battery was subjected to cyclic charge-discharge tests using the Blue Electric testing system. The test process was as follows: the battery was charged at a rate of 0.1C to a voltage of 4.25V, rested for 30 minutes, and then discharged at a rate of 0.1C to 2.8V; then charged at a rate of 0.33C to 4.25V, and charged at a constant voltage of 4.25V until the current ≤0.05C, rested for 30 minutes, and then discharged at a constant current of 0.33C to 2.8V. The capacity C and energy E at this point were recorded. The specific capacity = C / W (where W is the weight of the positive electrode material in the battery) and the voltage plateau = E / C were used to calculate the specific capacity and voltage plateau, respectively. The energy density of the positive electrode active material = specific capacity × voltage plateau. The test results are shown in Table 2.

[0173] Table 2 Performance tests of Examples 1-14 and Comparative Examples 1-4

[0174]

[0175] In the above examples and comparative examples, Examples 1-8 and Comparative Examples 2 and Comparative Example 1 form a control group, Examples 9-12 and Comparative Example 3 form a control group, and Examples 13-14 and Comparative Example 4 form a control group.

[0176] In this application, the cost reduction rate is used to measure the degree of cost reduction of the sodium-doped cathode active material, and the energy density reduction rate is used to measure the degree of energy density reduction of the sodium-doped cathode active material. A smaller cost reduction rate means less cost reduction for the material and less cost reduction for the battery; conversely, a smaller energy density reduction rate means less impact on the energy density of the material and less impact on the energy density of the battery.

[0177] As can be seen from Examples 1-14 and Comparative Examples 1, 3, and 4, by replacing part of the lithium in the positive electrode active material with sodium, it is possible to not significantly affect the energy density of the positive electrode active material, and to reduce the battery production cost to a large extent.

[0178] As can be seen from Examples 1-14 and Comparative Example 2, by controlling the proportion of substituted sodium to within 40%, the decrease in energy density of the positive electrode active material can be reduced.

[0179] As can be seen from Examples 2-6 and 9-12, by making 0.01≤x≤0.4 and x≤0.67-0.6a, the battery can further achieve both lower production costs and higher energy density.

[0180] As shown in Examples 4-6, 10-12 and 13-14, setting x ≤ 0.67-0.6a and 0.01 ≤ x ≤ 0.2 can reduce the impact on battery energy density; furthermore, setting x ≤ 0.67-0.6a and 0.05 ≤ x ≤ 0.15 can further reduce the impact on battery energy density while reducing battery production costs.

[0181] As can be seen from Examples 6-8, a variety of positive electrode active materials are applicable to the technical solution of this application, and replacing some cobalt and manganese with iron and aluminum can further reduce the production cost of the battery.

[0182] 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 positive electrode active material, characterized by, Comprising: Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2; wherein M1 comprises Fe, M2 comprises Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0 2. The positive electrode active material according to claim 1, characterized by At a voltage of 4.25V, the x and the a satisfy: x≤0.67-0.6a.

3. The positive electrode active material according to claim 1 or 2, characterized by 0.01≤x≤0.2。 4. The positive electrode active material according to any one of claims 1 to 3, characterized by, 0.05≤x≤0.15。 5. The positive electrode active material according to any one of claims 1 to 4, characterized by, The b and the c satisfy: 0.01≤b+c≤0.

3.

6. The positive electrode active material according to any one of claims 1 to 5, characterized by, The d and the e satisfy: 0.01≤d+e≤0.

45.

7. A production method for producing the positive electrode active material described in any one of claims 1 to 6, characterized by, Comprising: dissolving a lithium source, a sodium source, a nickel source, an iron source, a cobalt source, an aluminum source, and a manganese source in a solution of deionized water containing citric acid to obtain a mixed solution, a mass ratio of the lithium source, the sodium source, the nickel source, the iron source, the cobalt source, the aluminum source, and the manganese source to the mass of the citric acid being 1:1; subjecting the mixed solution to stirring and drying treatment to obtain a positive electrode active material precursor; subjecting the positive electrode active material precursor to sintering treatment to obtain the positive electrode active material; wherein the positive electrode active material comprises Li 1-x Na x Ni a M1 b Co c M2 d Mn e O2, M1 comprises Fe, M2 comprises Al, 0.01≤x≤0.4, 0.5≤a≤0.98, 0 8. The production method according to claim 7, characterized by, the stirring and drying treatment to obtain a positive electrode active material precursor, comprising: stirring the mixed solution under an atmosphere of 60℃ until a solid gel is formed; drying the solid gel under atmospheres of 100℃ and 400℃ for 12h and 4h, respectively, to obtain the positive electrode active material precursor.

9. The production method according to claim 7 or 8, characterized by, the sintering treatment to obtain the positive electrode active material, comprising: calcining the positive electrode active material precursor under an oxygen atmosphere at 750℃ for 20h to obtain the positive electrode active material.

10. A positive electrode sheet characterized by comprising: Comprising: a positive electrode current collector, and a positive electrode film layer arranged on at least one side of the positive electrode current collector; the positive electrode film layer comprising the positive electrode active material of any one of claims 1 to 6, or the positive electrode active material prepared by the preparation method of any one of claims 7 to 9.

11. A battery cell, characterized by The positive electrode sheet comprises the positive electrode active material of claim 10.

12. A battery, characterized by The battery cell comprises the positive electrode active material of claim 11.

13. An electrical device, characterized by The battery comprises the positive electrode active material of claim 12.

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