Positive electrode active material, positive electrode sheet, secondary battery, battery module, battery pack, and power using device

Abstract

The present application provides a positive electrode active material having a chemical formula Li a A x Mn 1‑y B y P 1‑z C z O 4‑n D n wherein the A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W, the B comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, the C comprises one or more elements selected from B, S, Si and N, the D comprises one or more elements selected from S, F, Cl and Br, the a is selected from the range of 0.9 to 1.1, the x is selected from the range of 0.001 to 0.1, the y is selected from the range of 0.001 to 0.5, the z is selected from the range of 0.001 to 0.1, the n is selected from the range of 0.001 to 0.1, and the positive electrode active material is electrically neutral. The positive electrode active material has improved rate capability, significantly reduces the elution of Mn and Mn site doping elements when used in a secondary battery, and achieves significantly improved cycle performance and high temperature stability.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a positive electrode active material, as well as a positive electrode sheet containing the same, a secondary battery, a battery module, a battery pack, and an electrical device. Background Technology

[0002] In recent years, with the development of lithium-ion rechargeable battery technology, lithium-ion rechargeable batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. Due to the significant advancements in lithium-ion rechargeable batteries, higher requirements have been placed on their energy density, cycle performance, and safety performance.

[0003] Lithium manganese phosphate (LMP) is a cathode active material for lithium-ion secondary batteries, boasting advantages such as high capacity, good safety, and low cost. However, its poor rate performance hinders its commercial application. Improving the rate and cycle performance of LPP through coating or doping are currently effective methods, but existing LPP cathode materials still require further improvement in rate performance, cycle performance, and high-temperature stability. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode active material for secondary batteries that improves the rate performance, cycle performance and / or high temperature stability compared with existing lithium manganese phosphate positive electrode active materials.

[0005] To achieve the above objectives, the first aspect of this application provides a positive electrode active material having the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n ,

[0006] Wherein, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W.

[0007] The element B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge.

[0008] The C includes one or more elements selected from B (boron), S, Si, and N.

[0009] The D includes one or more elements selected from S, F, Cl, and Br.

[0010] The value of a is selected from the range of 0.9 to 1.1, the value of x is selected from the range of 0.001 to 0.1, the value of y is selected from the range of 0.001 to 0.5, the value of z is selected from the range of 0.001 to 0.1, the value of n is selected from the range of 0.001 to 0.1, and the positive electrode active material is electrically neutral.

[0011] Therefore, by simultaneously doping specific elements in specific amounts at the Li, Mn, P and O sites of the compound LiMnPO4, this application can obtain significantly improved rate performance, while significantly reducing the dissolution of Mn and Mn-site dopants, resulting in significantly improved cycle performance and / or high-temperature stability, and the specific capacity and compaction density of the material can also be improved.

[0012] In any implementation, A, C, and D are each independently any one of the elements within their respective ranges, and B is at least two elements;

[0013] Optionally,

[0014] A is an element selected from Mg and Nb, and / or,

[0015] The element B is at least two elements selected from Fe, Ti, V, Co, and Mg, and optionally Fe and one or more elements selected from Ti, V, Co, and Mg, and / or,

[0016] The C is S, and / or,

[0017] The D is F.

[0018] This can further improve the rate performance, specific capacity, and / or high-temperature performance of secondary batteries.

[0019] In any embodiment, x is selected from the range of 0.001 to 0.005; and / or y is selected from the range of 0.01 to 0.5, optionally from the range of 0.25 to 0.5; and / or z is selected from the range of 0.001 to 0.005; and / or n is selected from the range of 0.001 to 0.005.

[0020] This can further improve the specific capacity and rate performance and / or kinetic performance of the material, and / or further improve the rate performance and / or high-temperature performance of the battery.

[0021] In any embodiment, (1-y):y is in the range of 1 to 4, optionally in the range of 1.5 to 3, and a:x is in the range of 9 to 1100, optionally in the range of 190-998. Thus, the energy density and cycle performance of the positive electrode active material can be further improved.

[0022] In any embodiment, the lattice change rate of the positive electrode active material is 8% or less, optionally 4% or less. This improves the rate performance of the battery cell.

[0023] In any embodiment, the concentration of Li / Mn antisite defects in the positive electrode active material is 2% or less, optionally 0.5% or less. This improves the specific capacity and rate performance of the positive electrode active material.

[0024] In any embodiment, the oxygen valence state on the surface of the positive electrode active material is below -1.82, optionally between -1.89 and -1.98. This improves the cycle performance and high-temperature stability of the battery cell.

[0025] In any embodiment, the compaction density of the positive electrode active material at 3T is 2.0 g / cm³. 3 The above is optional, 2.2 g / cm³. 3 The above. Therefore, the volumetric energy density of the battery cell can be increased.

[0026] In any embodiment, the surface of the positive electrode active material is coated with carbon. This improves the conductivity of the positive electrode active material.

[0027] A second aspect of this application also provides a method for preparing the positive electrode active material described in the first aspect of this application, comprising the following steps:

[0028] (1) Dissolve and stir the manganese source, the source of element B and the acid in a solvent to generate a suspension of manganese salt doped with element B. Filter the suspension and dry the filter cake to obtain manganese salt doped with element B.

[0029] (2) The lithium source, phosphorus source, source of element A, source of element C and source of element D, solvent and manganese salt doped with element B obtained in step (1) are added to the reaction vessel, ground and mixed to obtain a slurry;

[0030] (3) The slurry obtained in step (2) is transferred to a spray drying equipment for spray drying and granulation to obtain granules;

[0031] (4) The particles obtained in step (3) are sintered to obtain the positive electrode active material.

[0032] In any embodiment, the source of element A is selected from at least one of element A's elemental form, oxide, phosphate, oxalate, carbonate, and sulfate; the source of element B is selected from at least one of element B's elemental form, oxide, phosphate, oxalate, carbonate, and sulfate; the source of element C is selected from at least one of element C's sulfate, borate, nitrate, and silicate; and the source of element D is selected from at least one of element D's elemental form and ammonium salt.

[0033] Therefore, by selecting the source of each dopant element within the above-mentioned range, the performance of the material can be improved.

[0034] In any embodiment, the stirring in step (1) is carried out at a temperature in the range of 60-120°C.

[0035] In any embodiment, the stirring in step (1) is carried out at a stirring rate of 200 rpm to 800 rpm.

[0036] In any embodiment, the grinding and mixing in step (2) is carried out for 8 to 15 hours.

[0037] Therefore, by controlling the reaction temperature, stirring rate, and mixing time during doping, the dopant elements can be evenly distributed, and the crystallinity of the sintered material can be higher, thereby improving the specific capacity and rate performance of the material.

[0038] In any embodiment, the sintering in step (4) is carried out at a temperature range of 600°C to 900°C for 6 to 14 hours. This improves the high-temperature stability and cycle performance of the secondary battery.

[0039] In any embodiment, step (2) further includes adding a carbon source to the reaction vessel and grinding and mixing it together. This allows for the acquisition of a positive electrode active material with a carbon-coated surface.

[0040] A third aspect of this application provides a positive electrode sheet, which 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 the positive electrode active material described in the first aspect of this application or a positive electrode active material prepared by the method described in the second aspect of this application, and the content of the positive electrode active material in the positive electrode film layer is 10% by weight or more, based on the total weight of the positive electrode film layer.

[0041] In any embodiment, the content of the positive electrode active material in the positive electrode film layer is 95%-99.5% by weight, based on the total weight of the positive electrode film layer.

[0042] The fourth aspect of this application provides a secondary battery comprising the positive electrode active material of the first aspect of this application, or the positive electrode active material prepared by the method of the second aspect of this application, or the positive electrode sheet of the third aspect of this application.

[0043] A fifth aspect of this application provides a battery module that includes the secondary battery of the fourth aspect of this application.

[0044] A sixth aspect of this application provides a battery pack that includes the battery module of the fifth aspect of this application.

[0045] A seventh aspect of this application provides an electrical device comprising at least one selected from the fourth aspect of this application, the fifth aspect of this application, or the sixth aspect of this application. Attached Figure Description

[0046] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0047] Figure 1 X-ray diffraction (XRD) patterns of undoped LiMnPO4 and the positive electrode active material prepared in Example 2.

[0048] Figure 2 The image shows the X-ray energy dispersive spectroscopy (EDS) spectrum of the positive electrode active material prepared in Example 2.

[0049] Figure 3 This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0050] Figure 4 yes Figure 3 An exploded view of a secondary battery according to one embodiment of this application is shown.

[0051] Figure 5 This is a schematic diagram of a battery module according to one embodiment of this application.

[0052] Figure 6 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0053] Figure 7 yes Figure 6 An exploded view of a battery pack according to one embodiment of this application is shown.

[0054] Figure 8 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0055] Explanation of reference numerals in the attached figures:

[0056] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0057] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the positive electrode active material, its manufacturing method, positive electrode sheet, secondary battery, battery module, battery pack, and power-consuming 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. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0058] 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 particular 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 included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 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.

[0059] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0060] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0061] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably 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 mention that the method may also include step (c) indicates 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.

[0062] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0063] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A 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).

[0064] As a positive electrode active material for lithium-ion secondary batteries, lithium manganese phosphate has a disadvantage compared to other positive electrode active materials in terms of poor rate performance. Currently, this problem is usually solved by methods such as coating or doping. However, there is still a desire to further improve the rate performance, cycle performance, and high-temperature stability of lithium manganese phosphate positive electrode active materials.

[0065] In this application, by simultaneously doping specific elements in specific amounts at four positions (Li, Mn, P, and O) of lithium manganese phosphate, significantly improved rate performance, improved cycle performance, and / or high-temperature stability can be obtained, thereby obtaining an improved lithium manganese phosphate cathode active material.

[0066] The positive electrode active material of this application can be used, for example, in lithium-ion secondary batteries.

[0067] Specifically, the first aspect of this application proposes a positive electrode active material having the chemical formula Li a A x Mn 1- y B y P 1-z C z O 4-n D n ,

[0068] Wherein, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W.

[0069] The element B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge.

[0070] The C includes one or more elements selected from B (boron), S, Si, and N.

[0071] The D includes one or more elements selected from S, F, Cl, and Br.

[0072] The 'a' is selected from the range of 0.9 to 1.1, for example, 0.97, 0.977, 0.984, 0.988, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, 1.01; the 'x' is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005; and the 'y' is selected from the range of 0.001 to 0.5, for example, 0.001, 0. 0.05, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.34, 0.345, 0.349, 0.35, 0.4, where z is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1, and n is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1, and the positive electrode active material is electrically neutral.

[0073] Unless otherwise stated, in the above chemical formulas, when A consists of two or more elements, the limitation on the range of x values ​​described above applies not only to the stoichiometric coefficient of each element as A, but also to the sum of the stoichiometric coefficients of all elements as A. For example, when A consists of two or more elements A1, A2...An, the stoichiometric coefficients x1, x2...xn of each of A1, A2...An must each fall within the range of x values ​​defined in this application, and the sum of x1, x2...xn must also fall within this range. Similarly, for the case where B, C, and D consist of two or more elements, the limitation on the range of stoichiometric coefficients of B, C, and D in this application also has the above meaning.

[0074] The positive electrode active material of this application is obtained by elemental doping of the compound LiMnPO4, wherein A, B, C, and D are the elements doped at the Li, Mn, P, and O sites of the compound LiMnPO4, respectively. Not wishing to be confined to theory, it is now believed that the performance improvement of lithium manganese phosphate is related to reducing the lattice change rate of lithium manganese phosphate during lithium insertion / extraction and reducing surface activity. Reducing the lattice change rate can reduce the difference in lattice constants between the two phases at the grain boundary, reduce interfacial stress, and enhance Li... + The ability to transport substances at the interface improves the rate performance of the positive electrode active material. However, high surface activity can easily lead to severe interfacial side reactions, exacerbating gas generation, electrolyte consumption, and interface damage, thus affecting the battery's cycle performance. In this application, lattice change rate is reduced through Li and Mn doping. Mn doping also effectively reduces surface activity, thereby suppressing Mn dissolution and interfacial side reactions between the positive electrode active material and the electrolyte. P-site doping accelerates the change rate of Mn-O bond length, lowering the small polaron migration barrier and thus improving electronic conductivity. O-site doping has a good effect on reducing interfacial side reactions. P-site and O-site doping also affect the dissolution of Mn from antisite defects and the kinetic properties. Therefore, doping reduces the concentration of antisite defects in the material, improves the kinetic properties and specific capacity, and can also change the particle morphology, thereby increasing the compaction density. The applicant unexpectedly discovered that by simultaneously doping specific elements at specific amounts at the Li, Mn, P, and O sites of the compound LiMnPO4, it is possible to obtain significantly improved rate performance, while significantly reducing the dissolution of Mn and Mn-site dopants, resulting in significantly improved cycle performance and / or high-temperature stability, and also improving the specific capacity and compaction density of the material.

[0075] Optionally, A is one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B is one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C is one or more elements selected from B (boron), S, Si, and N; and D is one or more elements selected from S, F, Cl, and Br.

[0076] In some embodiments, A, C, and D are each independently any one element within their respective ranges, and B is at least two elements. This allows for easier and more accurate control of the composition of the positive electrode active material.

[0077] Optionally,

[0078] A is an element selected from Mg and Nb, and / or,

[0079] The element B is at least two elements selected from Fe, Ti, V, Co, and Mg, and optionally Fe and one or more elements selected from Ti, V, Co, and Mg, and / or,

[0080] The C is S, and / or,

[0081] The D is F.

[0082] By selecting doping elements at the Li sites within the aforementioned range, the lattice change rate during the lithium removal process can be further reduced, thereby further improving the rate performance of the battery. By selecting doping elements at the Mn sites within the aforementioned range, electronic conductivity can be further increased and the lattice change rate further reduced, thereby improving the rate performance and specific capacity of the battery. By selecting doping elements at the P sites within the aforementioned range, the rate performance of the battery can be further improved. By selecting doping elements at the O sites within the aforementioned range, interfacial side reactions can be further mitigated, improving the high-temperature performance of the battery.

[0083] In some embodiments, x is selected from the range of 0.001 to 0.005; and / or y is selected from the range of 0.01 to 0.5, optionally from the range of 0.25 to 0.5; and / or z is selected from the range of 0.001 to 0.005; and / or n is selected from the range of 0.001 to 0.005. By selecting a value of y within the above ranges, the specific capacity and rate performance of the material can be further improved. By selecting a value of x within the above ranges, the kinetic performance of the material can be further improved. By selecting a value of z within the above ranges, the rate performance of the secondary battery can be further improved. By selecting a value of n within the above ranges, the high-temperature performance of the secondary battery can be further improved.

[0084] In some embodiments, the positive electrode active material satisfies the following: (1-y): y is in the range of 1 to 4, optionally in the range of 1.5 to 3, and a:x is in the range of 9 to 1100, optionally in the range of 190-998. Here, y represents the sum of the stoichiometric coefficients of the Mn-site doping elements. When the above conditions are met, the energy density and cycle performance of the positive electrode active material can be further improved.

[0085] In some embodiments, the lattice change rate of the positive electrode active material is below 8%, and optionally, below 4%. Reducing the lattice change rate facilitates Li ion transport, meaning that Li ions have greater migration ability within the material, which is beneficial for improving the rate performance of the secondary battery. The lattice change rate can be measured using methods known in the art, such as X-ray diffraction (XRD).

[0086] In some embodiments, the Li / Mn antisite defect concentration of the positive electrode active material is below 2%, and optionally, the Li / Mn antisite defect concentration is below 0.5%. The term Li / Mn antisite defect refers to the presence of Li in the LiMnPO4 lattice. + With Mn 2+ The positions of Li and Mn are interchanged. The Li / Mn antisite defect concentration refers to the concentration of Li / Mn antisite defects in the positive electrode active material. 2+ Interchangeable Li + Zhan Li + Percentage of the total. Mn of the inversion defect. 2+ It will hinder Li + The transport of Li / Mn antisite defects, by reducing the concentration of Li / Mn antisite defects, is beneficial to improving the specific capacity and rate performance of the positive electrode active material. The concentration of Li / Mn antisite defects can be measured by methods known in the art, such as XRD.

[0087] In some embodiments, the surface oxygen valence state of the positive electrode active material is below -1.82, optionally between -1.89 and -1.98. By reducing the surface oxygen valence state, interfacial side reactions between the positive electrode active material and the electrolyte can be mitigated, thereby improving the cycle performance and high-temperature stability of the secondary battery. The surface oxygen valence state can be measured by methods known in the art, such as electron energy loss spectroscopy (EELS).

[0088] In some embodiments, the compaction density of the positive electrode active material at 3 tons is 2.0 g / cm³. 3 The above is an option, specifically 2.2 g / cm³. 3 The higher the compaction density, the greater the weight of active material per unit volume. Therefore, increasing the compaction density is beneficial for improving the volumetric energy density of the battery cell. Compaction density can be measured according to GB / T 24533-2009.

[0089] In some embodiments, the surface of the positive electrode active material is coated with carbon. This improves the conductivity of the positive electrode active material.

[0090] The second aspect of this application relates to a method for preparing the positive electrode active material of the first aspect of this application, which includes the following steps:

[0091] (1) Dissolve and stir the manganese source, the source of element B and the acid in a solvent to generate a suspension of manganese salt doped with element B. Filter the suspension and dry the filter cake to obtain manganese salt doped with element B.

[0092] (2) The lithium source, phosphorus source, source of element A, source of element C and source of element D, solvent and manganese salt doped with element B obtained in step (1) are added to the reaction vessel, ground and mixed to obtain a slurry;

[0093] (3) The slurry obtained in step (2) is transferred to a spray drying equipment for spray drying and granulation to obtain granules;

[0094] (4) The particles obtained in step (3) are sintered to obtain the positive electrode active material.

[0095] In some embodiments, the source of element A is selected from at least one of elemental form, oxide, phosphate, oxalate, carbonate, and sulfate; the source of element B is selected from at least one of elemental form, oxide, phosphate, oxalate, carbonate, and sulfate; the source of element C is selected from at least one of sulfate, borate, nitrate, and silicate of element C; and the source of element D is selected from at least one of elemental form and ammonium salt of element D. By selecting the source of each dopant element, the uniformity of the dopant element distribution can be improved, thereby improving the material performance.

[0096] In some embodiments, the acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and organic acids such as oxalic acid, for example, oxalic acid. In some embodiments, the acid is a dilute acid with a concentration of 60% by weight or less.

[0097] In some embodiments, the manganese source may be a manganese-containing substance known in the art that can be used to prepare lithium manganese phosphate, such as one or a combination of elemental manganese, manganese dioxide, manganese phosphate, manganese oxalate, and manganese carbonate.

[0098] In some embodiments, the lithium source may be a lithium-containing material known in the art that can be used to prepare lithium manganese phosphate, such as lithium carbonate, lithium hydroxide, lithium phosphate, lithium dihydrogen phosphate, or a combination thereof.

[0099] In some embodiments, the phosphorus source may be a phosphorus-containing substance known in the art that can be used to prepare lithium manganese phosphate, such as one or a combination of diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, and phosphoric acid.

[0100] The amount of source added for each of elements A, B, C, and D depends on the target doping amount, and the ratio of the amount of lithium source, manganese source, and phosphorus source used conforms to the stoichiometric ratio.

[0101] In some embodiments, the solvents described in steps (1) and (2) may each be a solvent commonly used by those skilled in the art in the preparation of manganese salts and lithium manganese phosphate, for example, each may be independently selected from at least one of ethanol, water (e.g., deionized water).

[0102] In some embodiments, the stirring in step (1) is carried out at a temperature in the range of 60°C to 120°C. In some embodiments, the stirring in step (1) is carried out at a stirring rate of 200 rpm to 800 rpm, or 300 rpm to 800 rpm, or 400 rpm to 800 rpm. In some embodiments, the stirring in step (1) is carried out for 6 to 12 hours. In some embodiments, the grinding and mixing in step (2) is carried out for 8 to 15 hours.

[0103] By controlling the reaction temperature, stirring rate, and mixing time during doping, the doping elements can be evenly distributed, and the crystallinity of the sintered material can be higher, thereby improving the material's specific capacity and rate performance.

[0104] In some embodiments, the filter cake may be washed before drying in step (1).

[0105] In some embodiments, the drying in step (1) can be carried out in a manner and under conditions known to those skilled in the art, for example, the drying temperature can be in the range of 120°C-300°C. Optionally, the filter cake can be ground into particles after drying, for example, ground to a median particle size Dv. 50 Within the range of 50nm-200nm. The median particle size Dv... 50 This refers to the particle size corresponding to a cumulative volume distribution percentage of the positive electrode active material reaching 50%. In this application, the median particle size Dv of the positive electrode active material... 50 Particle size can be determined using laser diffraction particle size analysis. For example, according to standard GB / T 19077-2016, a laser particle size analyzer (e.g., Malvern Master Size 3000) can be used for determination.

[0106] In some embodiments, a carbon source is also added to the reaction vessel in step (2) for grinding and mixing. Thus, the method yields a positive electrode active material with a carbon-coated surface. Optionally, the carbon source includes one or a combination of starch, sucrose, glucose, polyvinyl alcohol, polyethylene glycol, and citric acid. The amount of carbon source relative to the amount of lithium source is typically in the molar ratio range of 0.1% to 5%. The grinding can be performed by a suitable grinding method known in the art, such as sand milling.

[0107] The temperature and time for spray drying in step (3) can be the conventional temperature and time for spray drying in the art, for example, 1 hour to 6 hours at 100°C to 300°C.

[0108] In some embodiments, the sintering is carried out at a temperature range of 600°C to 900°C for 6 to 14 hours. By controlling the sintering temperature and time, the crystallinity of the material can be controlled, reducing the amount of Mn and Mn-site doped elements dissolved after cycling of the positive electrode active material, thereby improving the high-temperature stability and cycle performance of the battery.

[0109] In some embodiments, the sintering is carried out under a protective atmosphere, which may be nitrogen, an inert gas, hydrogen, or a mixture thereof.

[0110] A third aspect of this application provides a positive electrode sheet, which 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 the positive electrode active material of the first aspect of this application or the positive electrode active material prepared by the method of the second aspect of this application, and the content of the positive electrode active material in the positive electrode film layer is more than 10% by weight, based on the total weight of the positive electrode film layer.

[0111] In some embodiments, the positive electrode active material is present in the positive electrode film layer at a content of 95%-99.5% by weight, based on the total weight of the positive electrode film layer.

[0112] The fourth aspect of this application provides a secondary battery comprising the positive electrode active material of the first aspect of this application, or the positive electrode active material prepared by the method of the second aspect of this application, or the positive electrode sheet of the third aspect of this application.

[0113] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0114] The secondary battery, battery module, battery pack, and power-consuming device of this application will be described below with appropriate reference to the accompanying drawings.

[0115] [Positive electrode plate]

[0116] 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 including the positive electrode active material of the first aspect of this application.

[0117] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0118] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0119] In some embodiments, the positive electrode film layer 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.

[0120] In some embodiments, the positive electrode film 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.

[0121] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0122] [Negative electrode plate]

[0123] 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.

[0124] 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.

[0125] 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 substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0126] 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.

[0127] In some embodiments, the negative electrode film layer may optionally include an adhesive. The adhesive 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).

[0128] 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.

[0129] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0130] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as 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 a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0131] [Electrolytes]

[0132] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0133] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0134] 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.

[0135] 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.

[0136] In some embodiments, the electrolyte may optionally include additives. For example, 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.

[0137] [Isolation membrane]

[0138] In some embodiments, the secondary battery 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.

[0139] 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.

[0140] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0141] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0142] In some embodiments, the outer packaging of the secondary battery can be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The outer packaging of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic. As plastics, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed, etc.

[0143] This application does not particularly limit the shape of the secondary battery, and it can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 is a secondary battery 5 with a square structure as an example.

[0144] In some embodiments, referring to Figure 4 , the outer packaging can include a housing 51 and a top cover assembly 53. Among them, the housing 51 can include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0145] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries included 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.

[0146] Figure 5 is a battery module 4 as an example. Referring to Figure 5 , in the battery module 4, multiple secondary batteries 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Further, the multiple secondary batteries 5 can be fixed by fasteners.

[0147] Optionally, the battery module 4 can further include a housing with a receiving space, and multiple secondary batteries 5 are accommodated in the receiving space.

[0148] In some embodiments, the above battery module can also be assembled into a battery pack. The number of battery modules included in the battery pack 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 pack.

[0149] Figure 6 and Figure 7 is a battery pack 1 as an example. Referring to Figure 6 and Figure 7, a battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0150] In addition, the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application. The secondary battery, battery module, or battery pack can be used as the power source of the electric device or as the energy storage unit of the electric device. The electric device may include mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0151] As the electric device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0152] Figure 8 is an electric device as an example. The electric device is a pure electric vehicle, hybrid electric vehicle, or plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the secondary battery for this electric device, a battery pack or battery module can be used.

[0153] Another example of the device can be a mobile phone, tablet computer, laptop computer, etc. This device usually requires thinness and lightness, and a secondary battery can be used as the power source.

[0154] Embodiment

[0155] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For those not specified in the embodiments regarding specific technologies or conditions, the technologies or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0156] I. Preparation of secondary battery

[0157] Embodiment 1

[0158] 1) Preparation of positive electrode active material

[0159] Preparation of doped manganese oxalate: 1.3 mol of MnSO4﹒H2O and 0.7 mol of FeSO4﹒H2O were fully mixed in a mixer for 6 hours. The mixture was transferred to a reaction kettle, and 10 L of deionized water and 2 mol of oxalic acid dihydrate (calculated as oxalic acid) were added. The reaction kettle was heated to 80 °C and stirred at a speed of 600 rpm for 6 hours until the reaction terminated (no bubbles generated), obtaining an Fe-doped manganese oxalate suspension. Then, the suspension was filtered, and the filter cake was dried at 120 °C and then ground to obtain Fe-doped manganese oxalate particles with a median particle size Dv 50 of about 100 nm.

[0160] Preparation of doped lithium manganese phosphate: 1 mol of the above-mentioned manganese oxalate particles, 0.497 mol of lithium carbonate, 0.001 mol of Mo(SO4)3, an 85% phosphoric acid aqueous solution containing 0.999 mol of phosphoric acid, 0.001 mol of H4SiO4, 0.0005 mol of NH4HF2, and 0.005 mol of sucrose were added to 20 L of deionized water. The mixture was transferred to a sand mill and fully ground and stirred for 10 hours to obtain a slurry. The slurry was transferred to a spray drying device for spray drying granulation, setting the drying temperature at 250 °C and drying for 4 hours to obtain particles. In a protective atmosphere of nitrogen (90 vol%) + hydrogen (10 vol%), the above-mentioned powder was sintered at 700 °C for 10 hours to obtain carbon-coated Li 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 . The elemental content of the positive electrode active material can be detected by inductively coupled plasma emission spectroscopy (ICP).

[0161] 2) Preparation of coin cells

[0162] The above-mentioned positive electrode active material, polyvinylidene fluoride (PVDF), and acetylene black were added to N-methylpyrrolidone (NMP) in a weight ratio of 90:5:5 and stirred in a drying room to form a slurry. The slurry was coated on an aluminum foil, dried, and cold-pressed to form a positive electrode plate. The coating amount was 0.2 g / cm 2 , and the compaction density was 2.0 g / cm 3 .

[0163] A lithium sheet was used as the negative electrode, and a solution of 1 mol / L LiPF6 in ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) with a volume ratio of 1:1:1 was used as the electrolyte. Together with the positive electrode plate prepared above, a coin cell (hereinafter also referred to as "coin cell") was assembled in a coin cell box.

[0164] 3) Preparation of full cell

[0165] The above-mentioned positive electrode active material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were mixed evenly in an N-methylpyrrolidone solvent system according to a weight ratio of 92:2.5:5.5, then coated on aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet. The coating amount was 0.4 g / cm 2 , and the compaction density was 2.4 g / cm 3 .

[0166] The negative electrode active material artificial graphite, hard carbon, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were mixed evenly in deionized water according to a weight ratio of 90:5:2:2:1, then coated on copper foil, dried, and cold-pressed to obtain a negative electrode sheet. The coating amount was 0.2 g / cm 2 , and the compaction density was 1.7 g / cm 3 .

[0167] Using a polyethylene (PE) porous polymer film as the separator, the positive electrode sheet, separator, and negative electrode sheet were stacked in sequence, with the separator placed in the middle of the positive and negative electrodes to play a role in isolation, and then wound to obtain a bare battery cell. The bare battery cell was placed in an outer package, injected with the same electrolyte as that used in the preparation of the coin cell above, and sealed to obtain a full cell (hereinafter also referred to as "full battery").

[0168] Example 2

[0169] Except that in "1) Preparation of positive electrode active material", the amount of high-purity Li2CO3 was changed to 0.4885 mol, Mo(SO4)3 was replaced with MgSO4, the amount of FeSO4·H2O was changed to 0.68 mol, 0.02 mol of Ti(SO4)2 was added during the preparation of doped manganese oxalate, and H4SiO4 was replaced with HNO3, the rest was the same as in Example 1.

[0170] Example 3

[0171] Except that in "1) Preparation of positive electrode active material", the amount of high-purity Li2CO3 was changed to 0.496 mol, Mo(SO4)3 was replaced with W(SO4)3, and H4SiO4 was replaced with H2SO4, the rest was the same as in Example 1.

[0172] Example 4

[0173] Except in "1) Preparation of the positive electrode active material", where the amount of high-purity Li2CO3 was changed to 0.4985 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.0005 mol of Al2(SO4)3 and NH4HF2 was replaced with NH4HCl2, the rest was the same as in Example 1.

[0174] Example 5

[0175] Except in "1) Preparation of the positive electrode active material", where 0.7 mol of FeSO4﹒H2O was changed to 0.69 mol, 0.01 mol of VCl2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4965 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.0005 mol of Nb2(SO4)5 and H4SiO4 was replaced with H2SO4, the rest was the same as in Example 1.

[0176] Example 6

[0177] Except in "1) Preparation of the positive electrode active material", where the amount of FeSO4﹒H2O was changed to 0.68 mol, 0.01 mol of VCl2 and 0.01 mol of MgSO4 were added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4965 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.0005 mol of Nb2(SO4)5 and H4SiO4 was replaced with H2SO4, the rest was the same as in Example 1.

[0178] Example 7

[0179] Except in "1) Preparation of the positive electrode active material", where MgSO4 was replaced with CoSO4, the rest was the same as in Example 6.

[0180] Example 8

[0181] Except in "1) Preparation of the positive electrode active material", where MgSO4 was replaced with NiSO4, the rest was the same as in Example 6.

[0182] Example 9

[0183] Except in "1) Preparation of the positive electrode active material", where the amount of FeSO4﹒H2O was changed to 0.698 mol, 0.002 mol of Ti(SO4)2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4955 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.0​

[0184] Example 10

[0185] Except that in "1) Preparation of the positive electrode active material", the amount of FeSO4﹒H2O is changed to 0.68 mol, 0.01 mol of VCl2 and 0.01 mol of MgSO4 are also added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.4975 mol, 0.001 mol of Mo(SO4)3 is replaced by 0.0005 mol of Nb2(SO4)5 and NH4HF2 is replaced by NH4HBr2, the others are the same as in Example 1.

[0186] Example 11

[0187] Except that in "1) Preparation of the positive electrode active material", the amount of FeSO4﹒H2O is changed to 0.69 mol, 0.01 mol of VCl2 is also added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.499 mol, Mo(SO4)3 is replaced by MgSO4 and NH4HF2 is replaced by NH4HBr2, the others are the same as in Example 1.

[0188] Example 12

[0189] Except that in "1) Preparation of the positive electrode active material", the amount of MnSO4﹒H2O is changed to 1.36 mol, the amount of FeSO4﹒H2O is changed to 0.6 mol, 0.04 mol of VCl2 is also added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.4985 mol, Mo(SO4)3 is replaced by MgSO4 and H4SiO4 is replaced by HNO3, the others are the same as in Example 1.

[0190] Example 13

[0191] Except that in "1) Preparation of the positive electrode active material", the amount of MnSO4﹒H2O is changed to 1.16 mol and the amount of FeSO4﹒H2O is changed to 0.8 mol, the others are the same as in Example 12.

[0192] Example 14

[0193] Except that in "1) Preparation of the positive electrode active material", the amount of MnSO4﹒H2O is changed to 1.3 mol and the amount of VCl2 is changed to 0.1 mol, the others are the same as in Example 12.

[0194] Example 15

[0195] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.2 mol, 0.1 mol of VCl2 is also added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.494 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.005 mol of MgSO4, and H4SiO4 is replaced with H2SO4, the rest is the same as in Example 1.

[0196] Example 16

[0197] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.2 mol, 0.1 mol of VCl2 is also added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.467 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.005 mol of MgSO4, 0.001 mol of H4SiO4 is replaced with 0.005 mol of H2SO4, and 1.175 mol of 85% phosphoric acid is replaced with 1.171 mol of 85% phosphoric acid, the rest is the same as in Example 1.

[0198] Example 17

[0199] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.2 mol, 0.1 mol of VCl2 is also added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.492 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.005 mol of MgSO4, H4SiO4 is replaced with H2SO4, and 0.0005 mol of NH4HF2 is changed to 0.0025 mol, the rest is the same as in Example 1.

[0200] Example 18

[0201] Except in "1) Preparation of the positive electrode active material", where the amount of FeSO4﹒H2O is changed to 0.5 mol, 0.1 mol of VCl2 and 0.1 mol of CoSO4 are also added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.492 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.005 mol of MgSO4, H4SiO4 is replaced with H2SO4, and 0.0005 mol of NH4HF2 is changed to 0.0025 mol, the rest is the same as in Example 1.

[0202] Example 19

[0203] Except that in "1) Preparation of the positive electrode active material", the amount of FeSO4﹒H2O is changed to 0.4 mol, and 0.1 mol of CoSO4 is changed to 0.2 mol, other conditions are the same as in Example 18.

[0204] Example 20

[0205] Except that in "1) Preparation of the positive electrode active material", the amount of MnSO4﹒H2O is changed to 1.5 mol, the amount of FeSO4﹒H2O is changed to 0.1 mol, and the amount of CoSO4 is changed to 0.3 mol, other conditions are the same as in Example 18.

[0206] Example 21

[0207] Except that in "1) Preparation of the positive electrode active material", 0.1 mol of CoSO4 is replaced with 0.1 mol of NiSO4, other conditions are the same as in Example 18.

[0208] Example 22

[0209] Except that in "1) Preparation of the positive electrode active material", the amount of MnSO4﹒H2O is changed to 1.5 mol, the amount of FeSO4﹒H2O is changed to 0.2 mol, and 0.1 mol of CoSO4 is replaced with 0.2 mol of NiSO4, other conditions are the same as in Example 18.

[0210] Example 23

[0211] Except that in "1) Preparation of the positive electrode active material", the amount of MnSO4﹒H2O is changed to 1.4 mol, the amount of FeSO4﹒H2O is changed to 0.3 mol, and the amount of CoSO4 is changed to 0.2 mol, other conditions are the same as in Example 18.

[0212] Example 24

[0213] Except that in "1) Preparation of the positive electrode active material", 1.3 mol of MnSO4﹒H2O is changed to 1.2 mol, 0.7 mol of FeSO4﹒H2O is changed to 0.5 mol, 0.1 mol of VCl2 and 0.2 mol of CoSO4 are added during the preparation of doped manganese oxalate, the amount of Li2CO is changed to 0.497 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.005 mol of MgSO4, H4SiO4 is replaced with H2SO4, and 0.0005 mol of NH4HF2 is changed to 0.0025 mol, other conditions are the same as in Example 1.

[0214] Example 25

[0215] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.0 mol, the amount of FeSO4﹒H2O is changed to 0.7 mol, and the amount of CoSO4 is changed to 0.2 mol, the rest is the same as in Example 18.

[0216] Example 26

[0217] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.4 mol, the amount of FeSO4﹒H2O is changed to 0.3 mol, 0.1 mol of VCl2 and 0.2 mol of CoSO4 are added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.4825 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.005 mol of MgSO4, the amount of H4SiO4 is changed to 0.1 mol, the amount of phosphoric acid is changed to 0.9 mol, and the amount of NH4HF2 is changed to 0.04 mol, the rest is the same as in Example 1.

[0218] Example 27

[0219] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.4 mol, the amount of FeSO4﹒H2O is changed to 0.3 mol, 0.1 mol of VCl2 and 0.2 mol of CoSO4 are added during the preparation of doped manganese oxalate, the amount of Li2CO3 is changed to 0.485 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.005 mol of MgSO4, the amount of H4SiO4 is changed to 0.08 mol, the amount of phosphoric acid is changed to 0.92 mol, and the amount of NH4HF2 is changed to 0.05 mol, the rest is the same as in Example 1.

[0220] Comparative Example 1

[0221] Preparation of manganese oxalate: Add 1 mol of MnSO4﹒H2O to a reaction kettle, and add 10 L of deionized water and 1 mol of oxalic acid dihydrate (calculated as oxalic acid). Heat the reaction kettle to 80 °C and stir at a speed of 600 rpm for 6 hours. The reaction is terminated (no bubbles are generated) to obtain a manganese oxalate suspension. Then filter the suspension, dry the filter cake at 120 °C, and then grind it to obtain manganese oxalate particles with a median particle size Dv 50 of 50 - 200 nm.

[0222] Preparation of lithium manganese phosphate: Take 1 mol of the above-mentioned manganese oxalate particles, 0.5 mol of lithium carbonate, an 85% phosphoric acid aqueous solution containing 1 mol of phosphoric acid, and 0.005 mol of sucrose and add them to 20 L of deionized water. Transfer the mixture to a sand mill and grind and stir it thoroughly for 10 hours to obtain a slurry. Transfer the slurry to a spray drying device for spray drying granulation, set the drying temperature at 250 °C, and dry for 4 hours to obtain particles. Under a protective atmosphere of nitrogen (90 vol%) + hydrogen (10 vol%), sinter the above-mentioned powder at 700 °C for 10 hours to obtain carbon-coated LiMnPO4.

[0223] Comparative Example 2

[0224] [[ID=*6]]Except that in Comparative Example 1, 1 mol of MnSO4·H2O was replaced with 0.85 mol of MnSO4·H2O and 0.15 mol of FeSO4·H2O, and after adding them to a mixer and mixing thoroughly for 6 hours, then adding them to a reaction kettle, other operations were the same as those in Comparative Example 1.

[0225] Comparative Example 3

[0226] [[ID=*12]]Except that in "(1) Preparation of cathode active material", the amount of MnSO4·H2O was changed to 1.9 mol, 0.7 mol of FeSO4·H2O was replaced with 0.1 mol of ZnSO4, the amount of Li2CO3 was changed to 0.495 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of MgSO4, the amount of phosphoric acid was changed to 1 mol, H4SiO4 and NH4HF2 were not added, other operations were the same as those in Example 1.

[0227] Comparative Example 4

[0228] [[ID=*18]]Except that in "(1) Preparation of cathode active material", the amount of MnSO4·H2O was changed to 1.2 mol, the amount of FeSO4·H2O was changed to 0.8 mol, the amount of Li2CO3 was changed to 0.45 mol, 0.001 mol of Mo(SO4)3 was replaced with 0.005 mol of Nb2(SO4)5, 0.999 mol of phosphoric acid was changed to 1 mol, 0.0005 mol of NH4HF2 was changed to 0.025 mol, and H4SiO4 was not added, other operations were the same as those in Example 1.

[0229] Comparative Example 5

[0230] Note: The text in the original Chinese contains some chemical reaction and preparation process descriptions. The translated text above tries to maintain the same meaning and technical terms as accurately as possible. The parts marked with '*' are the key translated parts that convey the core content of the preparation process changes in each comparative example.Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.4 mol, the amount of FeSO4﹒H2O is changed to 0.6 mol, the amount of Li2CO3 is changed to 0.38 mol, and 0.001 mol of Mo(SO4)3 is replaced with 0.12 mol of MgSO4, the rest is the same as in Example 1.

[0231] Comparative Example 6

[0232] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 0.8 mol, 0.7 mol of FeSO4﹒H2O is replaced with 1.2 mol of ZnSO4, the amount of Li2CO3 is changed to 0.499 mol, and 0.001 mol of Mo(SO4)3 is replaced with 0.001 mol of MgSO4, the rest is the same as in Example 1.

[0233] Comparative Example 7

[0234] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.4 mol, the amount of FeSO4﹒H2O is changed to 0.6 mol, the amount of Li2CO3 is changed to 0.534 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.001 mol of MgSO4, the amount of phosphoric acid is changed to 0.88 mol, the amount of H4SiO4 is changed to 0.12 mol, and the amount of NH4HF2 is changed to 0.025 mol, the rest is the same as in Example 1.

[0235] Comparative Example 8

[0236] Except in "1) Preparation of the positive electrode active material", where the amount of MnSO4﹒H2O is changed to 1.2 mol, the amount of FeSO4﹒H2O is changed to 0.8 mol, the amount of Li2CO3 is changed to 0.474 mol, 0.001 mol of Mo(SO4)3 is replaced with 0.001 mol of MgSO4, the amount of phosphoric acid is changed to 0.93 mol, the amount of H4SiO4 is changed to 0.07 mol, and the amount of NH4HF2 is changed to 0.06 mol, the rest is the same as in Example 1.

[0237] II. Methods for Testing the Properties of the Positive Electrode Active Material and the Battery Performance

[0238] 1. Method for Measuring the Lattice Change Rate

[0239] Under a constant temperature environment of 25 °C, the positive electrode active material sample was placed in an XRD (model: Bruker D8 Discover), and the sample was tested at 1° / min. The test data was sorted and analyzed. Referring to the standard PDF card, the lattice constants a0, b0, c0, and v0 at this time were calculated (a0, b0, and c0 represent the lengths of each aspect of the unit cell, and v0 represents the unit cell volume, which can be directly obtained from the XRD refinement results).

[0240] Using the coin cell preparation method in the above-mentioned embodiment, the positive electrode active material sample was prepared into a coin cell, and the coin cell was charged at a small rate of 0.05C until the current decreased to 0.01C. Then, the positive electrode plate in the coin cell was taken out and immersed in DMC for 8 hours. Then it was dried, powdered, and the particles with a particle size less than 500 nm were screened out. Samples were taken and the lattice constant v1 was calculated in the same way as the above test of fresh samples. (v0 - v1) / v0×100% was used as the lattice change rate before and after complete lithium deintercalation and insertion and shown in the table.

[0241] 2. Measurement method of Li / Mn antisite defect concentration

[0242] The XRD results tested in the "lattice change rate measurement method" were compared with the PDF (Powder Diffraction File) card of the standard crystal to obtain the Li / Mn antisite defect concentration. Specifically, the XRD results tested in the "lattice change rate measurement method" were imported into the General Structure Analysis System (GSAS) software, and the refinement results were automatically obtained, which included the occupancy of different atoms. The Li / Mn antisite defect concentration was obtained by reading the refinement results.

[0243] 3. Measurement method of surface oxygen valence state

[0244] Take 5 g of the positive electrode active material sample and prepare it into a coin cell according to the coin cell preparation method described in the above-mentioned embodiment. The coin cell was charged at a small rate of 0.05C until the current decreased to 0.01C. Then, the positive electrode plate in the coin cell was taken out and immersed in DMC for 8 hours. Then it was dried, powdered, and the particles with a particle size less than 500 nm were screened out. The obtained particles were measured by electron energy loss spectroscopy (EELS, the instrument model used was Talos F200S) to obtain the energy loss near-edge structure (ELNES), which reflects the density of states and energy level distribution of elements. According to the density of states and energy level distribution, the number of occupied electrons was calculated by integrating the valence band density of states data, and thus the valence state of the surface oxygen after charging was deduced.

[0245] 4. Measurement method of tap density

[0246] Take 5 g of the powder and place it in a special compaction mold (CARVER mold from the United States, model 13 mm). Then place the mold on a compaction density instrument. Apply a pressure of 3 T and read the thickness of the powder under the pressure (the thickness after pressure relief) on the equipment. Calculate the compaction density through ρ = m / v.

[0247] 5. Measurement method for the dissolution amount of Mn (and Fe doped at the Mn site) after cycling

[0248] Discharge the full cell cycled at 45 °C until the capacity decays to 80% at a rate of 0.1 C to the cut-off voltage of 2.0 V. Then disassemble the cell, take out the negative electrode plate, and randomly take 30 circular pieces with a unit area of 1540.25 mm 2 ). Test the inductively coupled plasma emission spectroscopy (ICP) using an Agilent ICP-OES730. Calculate the amounts of Fe (if Fe is doped at the Mn site of the positive electrode active material) and Mn based on the ICP results, and thus calculate the dissolution amount of Mn (and Fe doped at the Mn site) after cycling. The test standard is based on EPA-6010D-2014.

[0249] 6. Measurement method for the initial specific capacity of a coin cell

[0250] Charge the coin cell at a rate of 0.1 C to 4.3 V at 2.5 - 4.3 V, then charge it at a constant voltage of 4.3 V until the current is less than or equal to 0.05 mA, let it stand for 5 min, and then discharge it at a rate of 0.1 C to 2.0 V. The discharge capacity at this time is the initial specific capacity, denoted as D0.

[0251] 7. Measurement method for the 3C charge constant current ratio

[0252] In a constant temperature environment of 25 °C, let the fresh full cell stand for 5 min, discharge it at a rate of 1 / 3 C to 2.5 V. Let it stand for 5 min, charge it at a rate of 1 / 3 C to 4.3 V, and then charge it at a constant voltage of 4.3 V until the current is less than or equal to 0.05 mA. Let it stand for 5 min and record the charging capacity at this time as C0. Discharge it at a rate of 1 / 3 C to 2.5 V, let it stand for 5 min, and then charge it at a rate of 3 C to 4.3 V, let it stand for 5 min, and record the charging capacity at this time as C1. The 3C charge constant current ratio is C1 / C0 × 100%.

[0253] The higher the 3C charge constant current ratio, the better the rate performance of the battery.

[0254] 8. 45 °C cycle performance test of the full cell

[0255] In a constant temperature environment of 45 °C, at 2.5 - 4.3 V, charge the full cell at 1C to 4.3 V, then charge at a constant voltage of 4.3 V until the current is less than or equal to 0.05 mA. Let it stand for 5 min, then discharge at 1C to 2.5 V, and record the discharge capacity at this time as D0. Repeat the above charge-discharge cycle until the discharge capacity drops to 80% of D0. Record the number of cycles the battery has gone through at this time.

[0256] 9. Full cell gas evolution test at 60 °C

[0257] Store the full cell in a 100% charged state (SOC) at 60 °C. Measure the open circuit voltage (OCV) and AC internal resistance (IMP) of the cell before, during, and after storage to monitor the SOC, and measure the volume of the cell. Among them, take out the full cell every 48 h of storage, let it stand for 1 h, then test the open circuit voltage (OCV) and internal resistance (IMP), and measure the volume of the cell by the drainage method after cooling to room temperature. The drainage method is to first measure the gravity F1 of the cell alone with a balance that automatically performs unit conversion of the dial data, and then place the cell completely in deionized water (the known density is 1 g / cm 3 ) and measure the gravity F2 of the cell at this time. The buoyancy F 浮 of the cell is F1 - F2, and then according to Archimedes' principle F 浮 , calculate the volume V of the cell = (F1 - F2) / .

[0258] Judging from the test results of OCV and IMP, during the entire storage process of this experiment, the batteries of the examples always maintained an SOC of more than 99%.

[0259] After storing for 30 days, measure the volume of the cell, and calculate the percentage increase in the volume of the cell after storage relative to the volume of the cell before storage.

[0260] In addition, measure the residual capacity of the cell. At 2.5 - 4.3 V, charge the full cell at 1C to 4.3 V, then charge at a constant voltage of 4.3 V until the current is less than or equal to 0.05 mA. Let it stand for 5 min, and record the charging capacity at this time as the residual capacity of the cell.

[0261] Table 1 shows the compositions of the positive active materials of Examples 1 - 11 and Comparative Examples 1 - 8. Table 2 shows the performance data of the positive active materials of Examples 1 - 11 and Comparative Examples 1 - 8, either in coin cells or full cells, measured according to the above performance test methods. Table 3 shows the compositions of the positive active materials of Examples 12 - 27. Table 4 shows the performance data of the positive active materials of Examples 12 - 27, either in coin cells or full cells, measured according to the above performance test methods.

[0262] Table 1 Composition of the positive electrode active materials of Examples 1-11 and Comparative Examples 1-8

[0263]

[0264] Table 2 Performance data of the positive electrode active materials of Examples 1-11 and Comparative Examples 1-8, measured by button cell or full cell according to the above performance test method

[0265]

[0266] Table 3 Composition of the positive electrode active materials of Examples 12-27

[0267]

[0268] Table 4 Performance data of the positive electrode active materials of Examples 12-27, measured by button cell or full cell according to the above performance test method

[0269]

[0270] Examples 28-41

[0271] The positive electrode active materials, button cells, and full cells were prepared in the same manner as in Example 1, but the stirring speed, temperature, grinding and stirring time in the sand mill, sintering temperature, and sintering time during the preparation of doped manganese oxalate were changed, as shown in Table 5 below.

[0272] Moreover, the performance data of the positive electrode active materials, button cells, or full cells of Examples 28-41 were measured according to the above performance test method, as shown in Table 6.

[0273] Table 5 Stirring speed, temperature, grinding and stirring time in the sand mill, sintering temperature, and sintering time during the preparation of doped manganese oxalate in Examples 28-41

[0274]

[0275] Table 6 Performance data of the positive electrode active materials, button cells, or full cells of Examples 28-41, measured according to the above performance test method

[0276]

[0277] Examples 42-54

[0278] The positive electrode active materials, button cells, and full cells were prepared in the same manner as in Example 1, but the lithium source, manganese source, phosphorus source, and sources of doping elements A, B, C, and D were changed, as shown in Table 7 below. The composition of the obtained positive electrode active materials was the same as that of Example 1, i.e., all were Li 0.994 Mo 0.001 Mn 0.65 Fe0.35 P 0.999 Si 0.001 O 3.999 F 0.001 。

[0279] Moreover, performance data of the positive electrode active materials, coin cells or full cells of Examples 42 - 54 were measured according to the above performance test methods, as shown in Table 8.

[0280] Table 7 Sources of lithium source, manganese source, phosphorus source and doping elements A, B, C, D in Examples 42 - 54

[0281]

[0282] Table 8 Performance data of the positive electrode active materials, coin cells or full cells of Examples 42 - 54 measured according to the above performance test methods

[0283]

[0284] As can be seen from Tables 2, 4, 6, and 8 above, each positive electrode active material of the embodiments of the present application has achieved better effects than the comparative examples in one or even all aspects of cycle performance, high - temperature stability, specific capacity, and tap density.

[0285] By comparing between Examples 18 - 20 and 23 - 25, it can be seen that when other elements are the same, within the range of (1 - y):y from 1 to 4, the energy density and cycle performance of the secondary battery can be further improved.

[0286] Figure 1 The XRD patterns of undoped LiMnPO4 and the positive electrode active material prepared in Example 2 are shown. It can be seen from the figure that the positions of the main characteristic peaks in the XRD pattern of the positive electrode active material of Example 2 are the same as those of undoped LiMnPO4, indicating that no impurity phase is introduced during the doping process, and the improvement of performance is mainly due to element doping rather than impurity phases.

[0287] Figure 2 The EDS spectrum of the positive electrode active material prepared in Example 2 is shown. The dotted - distributed elements in the figure are the doping elements. It can be seen from the figure that the element doping in the positive electrode active material of Example 2 is uniform.

[0288] It should be noted that the present application is not limited to the above - mentioned embodiments. The above - mentioned embodiments are only examples, and embodiments with the same structure in essence as the technical idea and achieving the same effect within the technical solution scope of the present application are all included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that those skilled in the art can think of to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode active material, characterized in that, It has the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n , Wherein, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W. The element B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge. The C includes one or more elements selected from boron, S, Si, and N. The D includes one or more elements selected from S, F, Cl, and Br. The value of a is selected from the range of 0.9 to 1.1, the value of x is selected from the range of 0.001 to 0.1, the value of y is selected from the range of 0.001 to 0.5, the value of z is selected from the range of 0.001 to 0.1, the value of n is selected from the range of 0.001 to 0.1, and the positive electrode active material is electrically neutral.

2. The positive electrode active material according to claim 1, characterized in that, A, C, and D are each independently any one of the elements within their respective ranges, and B is at least two elements within its range.

3. The positive electrode active material according to claim 1, characterized in that, A is an element selected from Mg and Nb, and / or, The element B is selected from at least two elements chosen from Fe, Ti, V, Co, and Mg, and / or, The C is S, and / or, The D is F.

4. The positive electrode active material according to claim 1, characterized in that, The B is Fe and one or more elements selected from Ti, V, Co and Mg.

5. The positive electrode active material according to claim 1, characterized in that, The x is selected from the range of 0.001 to 0.005; and / or the y is selected from the range of 0.01 to 0.5; and / or the z is selected from the range of 0.001 to 0.005; and / or the n is selected from the range of 0.001 to 0.

005.

6. The positive electrode active material according to claim 5, characterized in that, The value of y is selected from the range of 0.25 to 0.

5.

7. The positive electrode active material according to claim 1, characterized in that, (1-y): y is in the range of 1 to 4, and a:x is in the range of 9 to 1100.

8. The positive electrode active material according to claim 7, characterized in that, (1-y): y is in the range of 1.5 to 3.

9. The positive electrode active material according to claim 7, characterized in that, a:x is in the range of 190-998.

10. The positive electrode active material according to claim 1, characterized in that, Its lattice variation rate is below 8%.

11. The positive electrode active material according to claim 1, characterized in that, Its lattice variation rate is less than 4%.

12. The positive electrode active material according to claim 1, characterized in that, Its Li / Mn antisite defect concentration is below 2%.

13. The positive electrode active material according to claim 1, characterized in that, Its Li / Mn antisite defect concentration is below 0.5%.

14. The positive electrode active material according to claim 1, characterized in that, Its surface oxygen valence state is below -1.

82.

15. The positive electrode active material according to claim 1, characterized in that, Its surface oxygen valence state is -1.89 to -1.

98.

16. The positive electrode active material according to claim 1, characterized in that, Its compaction density at 3T is 2.0 g / cm³. 3 above.

17. The positive electrode active material according to claim 1, characterized in that, Its compaction density at 3T is 2.2 g / cm³. 3 above.

18. The positive electrode active material according to any one of claims 1 to 17, characterized in that, Its surface is coated with carbon.

19. A method for preparing the positive electrode active material according to any one of claims 1 to 18, comprising the following steps: (1) Dissolve and stir the manganese source, the source of element B and the acid in a solvent to generate a suspension of manganese salt doped with element B. Filter the suspension and dry the filter cake to obtain manganese salt doped with element B. (2) The lithium source, phosphorus source, source of element A, source of element C and source of element D, solvent and manganese salt doped with element B obtained in step (1) are added to the reaction vessel, ground and mixed to obtain a slurry; (3) The slurry obtained in step (2) is transferred to a spray drying equipment for spray drying and granulation to obtain granules; (4) The particles obtained in step (3) are sintered to obtain the positive electrode active material.

20. The method according to claim 19, characterized in that, The source of element A is selected from at least one of the simple substance, oxide, phosphate, oxalate, carbonate and sulfate of element A; the source of element B is selected from at least one of the simple substance, oxide, phosphate, oxalate, carbonate and sulfate of element B; the source of element C is selected from at least one of the sulfate, borate, nitrate and silicate of element C; and the source of element D is selected from at least one of the simple substance and ammonium salt of element D.

21. The method according to claim 19, characterized in that, The stirring in step (1) is carried out at a temperature in the range of 60-120°C, and / or, The stirring in step (1) is carried out at a stirring rate of 200 rpm to 800 rpm.

22. The method according to claim 19, characterized in that, The grinding and mixing in step (2) shall be carried out for 8-15 hours.

23. The method according to claim 19, characterized in that, The sintering in step (4) is carried out at a temperature range of 600℃-900℃ for 6-14 hours.

24. The method according to claim 19, characterized in that, Step (2) also includes adding a carbon source to the reaction vessel and grinding and mixing them together.

25. A positive electrode sheet comprising 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 comprising a positive electrode active material according to any one of claims 1 to 18 or a positive electrode active material prepared by any one of claims 19 to 24, and the positive electrode active material having a content of 10% by weight or more in the positive electrode film layer based on the total weight of the positive electrode film layer.

26. The positive electrode sheet according to claim 25, characterized in that... The content of the positive electrode active material in the positive electrode film is 95%-99.5% by weight, based on the total weight of the positive electrode film.

27. A secondary battery, characterized in that, The positive electrode active material includes any one of claims 1 to 18, or a positive electrode active material prepared by any one of claims 19 to 24, or a positive electrode sheet according to any one of claims 25 to 26.

28. A battery module, characterized in that, Includes the secondary battery as described in claim 27.

29. A battery pack, characterized in that, Includes the battery module as described in claim 28.

30. An electrical device, characterized in that, It includes at least one selected from the secondary battery of claim 27, the battery module of claim 28, or the battery pack of claim 29.

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