Cathode material composition, method of making the same, and cathode sheet, secondary battery, and power using device comprising the same

Abstract

The present application provides a positive electrode material composition, a preparation method thereof, and a positive electrode sheet, a secondary battery and an electric device comprising the same. The positive electrode material composition comprises a positive electrode active material and an organic polysiloxane compound, wherein the positive electrode active material has a chemical formula Li a A x Mn 1‑y B y P 1‑z C z O 4‑n D n The positive electrode material composition of the present application can make the secondary battery have a higher energy density, while also taking into account improving the rate performance, cycle performance and / or high temperature stability of the secondary battery.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a positive electrode material composition, its preparation method, and a positive electrode sheet, secondary battery, and electrical device containing the same. Background Technology

[0002] In recent years, 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 cars, military equipment, aerospace, and many other fields. With the application and promotion of rechargeable batteries, their safety performance has received increasing attention. Lithium manganese phosphate has become one of the most popular cathode active materials due to its advantages such as high capacity, good safety performance, and abundant raw material sources. However, lithium manganese phosphate is prone to manganese ion dissolution during charging, leading to rapid capacity decay. Summary of the Invention

[0003] The purpose of this application is to provide a positive electrode material composition, a method for preparing the same, and a positive electrode sheet, a secondary battery, and an electrical device comprising the same. The positive electrode material composition enables the secondary battery to have a high energy density, while also improving the rate performance, cycle performance, and / or high-temperature stability of the secondary battery.

[0004] The first aspect of this application provides a positive electrode material composition comprising a positive electrode active material and an organopolysiloxane compound, wherein the positive electrode active material has the chemical formula Li a A x Mn1- y B y P 1-z C z O 4-n D n 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 (boron), 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.

[0005] This application achieves improved rate performance by simultaneously doping specific elements at the Li, Mn, P, and O sites of the compound LiMnPO4 in specific amounts. Simultaneously, it reduces the dissolution of Mn and Mn-site dopants, resulting in improved cycle performance and / or high-temperature stability. Furthermore, the specific capacity and compaction density of the cathode active material are also increased. Combining the cathode active material of this application with an organopolysiloxane compound can mitigate the erosion of the cathode active material surface by the electrolyte and reduce the dissolution of Mn and Mn-site dopants, thereby improving the electrochemical performance of the cathode active material. Therefore, cathode electrodes and secondary batteries using the cathode material composition of this application can achieve high energy density while also exhibiting improved rate performance, cycle performance, and / or high-temperature stability.

[0006] In any embodiment of this application, the organopolysiloxane compound comprises at least one structural unit represented by Formula 1.

[0007]

[0008] R1 and R2 independently represent H or at least one of the following functional groups: -COOH, -OH, -SH, -CN, -SCN, amino, phosphate ester, carboxylic acid ester, amide, aldehyde, sulfonyl, polyether segment, C1-C20 aliphatic hydrocarbon, C1-C20 halogenated aliphatic hydrocarbon, C1-C20 heteroaliphatic hydrocarbon, C1-C20 halogenated heteroaliphatic hydrocarbon, C6-C20 aromatic hydrocarbon, C6-C20 halogenated aromatic hydrocarbon, C2-C20 heteroaromatic hydrocarbon, C2-C20 halogenated heteroaromatic hydrocarbon. Optionally, R1 and R2 each independently represent H or at least one of the following functional groups: -COOH, -OH, -SH, amino, phosphate ester, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, phenyl. More preferably, R1 and R2 each independently represent H or at least one of the following functional groups: -OH, -SH, amino, phosphate ester, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl. This can reduce the dissolution of Mn and Mn-site dopants, significantly improving the battery's cycle performance and / or high-temperature stability.

[0009] In any embodiment of this application, the organopolysiloxane compound includes one or more selected from linear polysiloxanes and cyclic polysiloxanes. Optionally, the organopolysiloxane compound is selected from linear polysiloxanes.

[0010] Therefore, this can further alleviate the erosion of the positive electrode active material surface by acidic substances in the electrolyte, reduce the dissolution of Mn and Mn-site dopants, and thus significantly improve the battery's cycle performance and storage performance. Because the electrons in the ring structure of cyclic polysiloxanes have a certain degree of delocalization, compared with linear polysiloxanes, their Si-O framework has a lower affinity for electron-rich F-containing ions, resulting in a slightly lower removal rate of F-containing ions in the electrolyte, a slightly weaker effect in reducing the dissolution of Mn and Mn-site dopants, and a slightly poorer improvement effect on battery cycle performance.

[0011] In any embodiment of this application, the linear polysiloxane further comprises end-capping groups. Optionally, the end-capping groups comprise at least one of the following functional groups: polyether, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, C6-C20 aromatic hydrocarbon, C1-C8 alkoxy, C2-C8 epoxy, hydroxyl, C1-C8 hydroxyalkyl, amino, C1-C8 aminoalkyl, carboxyl, and C1-C8 carboxyalkyl.

[0012] In any embodiment of this application, the linear polysiloxane includes one or more of the following: polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrosiloxane, carboxyl-functionalized polysiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, mercaptopropylpolysiloxane, aminoethylaminopropylpolydimethylsiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, terminal epoxy-terminated polydimethylsiloxane, terminal hydroxyl-terminated polydimethylsiloxane, terminal polyether polydimethylsiloxane, side-chain aminopropyl polysiloxane, side-chain hydroxymethyl polysiloxane, side-chain hydroxypropyl polysiloxane, side-chain polyether-grafted polydimethylsiloxane, and side-chain phosphate-grafted polydimethylsiloxane. Optionally, the linear polysiloxane includes one or more of polydimethylsiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, mercaptopropyl polysiloxane, aminoethylaminopropyl polydimethylsiloxane, hydroxyl-terminated polydimethylsiloxane, end-group polyether polydimethylsiloxane, and side-chain phosphate-grafted polydimethylsiloxane.

[0013] In any embodiment of this application, the cyclic polysiloxane comprises one or more of cyclic polydimethylsiloxane, cyclic polymethylvinylsiloxane, cyclic polymethylhydrosiloxane, and cyclic polymethyltrifluoropropylsiloxane. Optionally, the cyclic polysiloxane comprises one or more of 1,3,5,7-octamethylcyclotetrasiloxane, 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, cyclopentapolydimethylsiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, hexadecylcyclooctasiloxane, and tetradecylcycloheptasiloxane.

[0014] In any embodiment of this application, the number average molecular weight of the organopolysiloxane compound is below 300,000, optionally between 400 and 80,000. This enables the battery to simultaneously achieve good kinetic performance and high-temperature stability.

[0015] In any embodiment of this application, the mass percentage of polar functional groups in the organopolysiloxane compound is α, where 0 ≤ α < 50%, and optionally, 5% ≤ α ≤ 30%. This can better improve the cycle performance and / or high-temperature stability of the battery.

[0016] In any embodiment of this application, the content of the organopolysiloxane compound is from 0.01% to 2% by weight, optionally from 0.1% to 2% by weight, based on the total weight of the cathode material composition. This can better improve the cycle performance and / or high-temperature stability of the battery.

[0017] In any embodiment of this application, the surface of the positive electrode active material is further coated with carbon. This improves the conductivity of the positive electrode active material.

[0018] In any embodiment of this application, 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.

[0019] Optionally, A is any element selected from Mg and Nb.

[0020] Optionally, B is at least two elements selected from Fe, Ti, V, Co and Mg, and more specifically, Fe and one or more elements selected from Ti, V, Co and Mg.

[0021] Optionally, C is S.

[0022] Optionally, D is F.

[0023] This can further improve the rate performance, energy density, and / or high-temperature stability of the battery.

[0024] In any embodiment of this application, 'a' is selected from the range of 0.97 to 1.01.

[0025] In any embodiment of this application, x is selected from the range of 0.001 to 0.005. This further enhances the kinetic performance of the positive electrode active material.

[0026] In any embodiment of this application, y is selected from the range of 0.25 to 0.5. This allows for further improvement in the specific capacity and rate performance of the positive electrode active material.

[0027] In any embodiment of this application, z is selected from the range of 0.001 to 0.005. This allows for further improvement in the rate performance of the battery.

[0028] In any embodiment of this application, n is selected from the range of 0.001 to 0.005. This further improves the high-temperature stability of the battery.

[0029] In any embodiment of this application, (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. Therefore, the energy density and cycle performance of the battery can be further improved.

[0030] In any embodiment of this application, 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.

[0031] In any embodiment of this application, the Li / Mn antisite defect concentration of 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.

[0032] In any embodiment of this application, the surface oxygen valence state of the positive electrode active material is below -1.82, optionally from -1.89 to -1.98. This improves the battery's cycle performance and high-temperature stability.

[0033] In any embodiment of this application, 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 can be increased.

[0034] In any embodiment of this application, the positive electrode material composition further comprises a conductive agent and a binder. Optionally, the binder content is 1.79% to 10% by weight, based on the total weight of the positive electrode material composition. Optionally, the conductive agent content is 0.2% to 10% by weight, based on the total weight of the positive electrode material composition.

[0035] In any embodiment of this application, the powder resistivity of the cathode material composition at 12 MPa is 4 Ω / cm to 50 Ω / cm, optionally 4 Ω / cm to 40 Ω / cm. This enables the battery to have better kinetic performance.

[0036] In any embodiment of this application, the specific surface area of ​​the positive electrode material composition is 8m². 2 / g to 20m 2 / g, optionally 8m 2 / g to 15m 2 / g. This allows the battery to have better electrochemical performance.

[0037] The second aspect of this application provides a method for preparing a positive electrode material composition, comprising the following steps: (1) dissolving and stirring a manganese source, a source of element B, and an acid in a solvent to generate a suspension of manganese salt doped with element B, filtering the suspension and drying the filter cake to obtain manganese salt doped with element B; (2) adding a lithium source, a phosphorus source, a source of element A, a source of element C, and a source of element D, a solvent, and the manganese salt doped with element B obtained in step (1) into a reaction vessel for grinding and mixing to obtain a slurry; (3) transferring the slurry obtained in step (2) to a spray drying device for spray drying and granulation to obtain particles; (4) sintering the particles obtained in step (3) to obtain a positive electrode active material; (5) mixing the positive electrode active material obtained in step (4) with an organopolysiloxane compound, an optional binder, and an optional conductive agent to obtain a positive electrode material composition, wherein the positive electrode active material has the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D nThe 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, No, and Ge; the C comprises one or more elements selected from B (boron), 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.

[0038] In any embodiment of this application, the stirring in step (1) is carried out at a temperature in the range of 60-120°C.

[0039] In any embodiment of this application, the stirring in step (1) is carried out at a stirring rate of 200-800 rpm.

[0040] In any embodiment of this application, the grinding and mixing in step (2) is carried out for 8-15 hours.

[0041] Therefore, 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 specific capacity and rate performance of the positive electrode active material.

[0042] In any embodiment of this application, the sintering in step (4) is carried out at a temperature range of 600-900°C for 6-14 hours. This improves the high-temperature stability and cycle performance of the battery.

[0043] In any embodiment of this application, 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.

[0044] 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 surface of the positive current collector, wherein the positive electrode film layer comprises a positive electrode material composition of the first aspect of this application or a positive electrode material composition prepared by the method of the second aspect of this application, and the content of the positive electrode material composition in the positive electrode film layer is 50% by weight or more, based on the total weight of the positive electrode film layer.

[0045] In any embodiment of this application, the content of the positive electrode material composition in the positive electrode film layer is 90% to 100% by weight, based on the total weight of the positive electrode film layer.

[0046] In any embodiment of this application, the solid-liquid contact angle between the positive electrode film and the non-aqueous organic solvent is between 3° and 90°, optionally between 3° and 60°, and further between 10° and 30°. When the contact angle is within a suitable range, the battery can simultaneously achieve high energy density, good rate performance, cycle performance, and high-temperature stability.

[0047] In any embodiment of this application, the porosity of the positive electrode film is 15% to 50%, optionally 20% to 40%. When the porosity is within a suitable range, the battery can simultaneously achieve high energy density, good rate performance, cycle performance, and high-temperature stability.

[0048] The fourth aspect of this application provides a secondary battery, including a positive electrode material composition of the first aspect of this application, or a positive electrode material composition prepared by the method of the second aspect of this application, or a positive electrode sheet of the third aspect of this application.

[0049] The fifth aspect of this application provides an electrical device, including the secondary battery of the fourth aspect of this application.

[0050] The positive electrode sheet, secondary battery, and electrical device of this application include the positive electrode material composition of this application, and therefore have at least the same advantages as the positive electrode material composition. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of one embodiment of the secondary battery of this application.

[0053] Figure 2 yes Figure 1 An exploded view of the implementation method of the secondary battery.

[0054] Figure 3 This is a schematic diagram of one embodiment of the battery module of this application.

[0055] Figure 4 This is a schematic diagram of one embodiment of the battery pack of this application.

[0056] Figure 5 yes Figure 4 An exploded view of an embodiment of the battery pack shown.

[0057] Figure 6This is a schematic diagram of one embodiment of an electrical device that uses a secondary battery as a power source, as described in this application.

[0058] Figure 7 The X-ray diffraction (XRD) patterns of undoped LiMnPO4 and the positive electrode active material prepared in Example 2 are shown.

[0059] Figure 8 The X-ray energy dispersive spectroscopy (EDS) spectrum of the positive electrode active material prepared in Example 2 is shown.

[0060] The accompanying drawings are not necessarily drawn to scale. The reference numerals are as follows: 1 Battery pack, 2 Upper casing, 3 Lower casing, 4 Battery module, 5 Secondary battery, 51 Housing, 52 Electrode assembly, 53 Cover plate. Detailed Implementation

[0061] The following detailed description, with appropriate reference to the accompanying drawings, discloses the positive electrode material composition, its preparation method, and embodiments of the positive electrode sheet, secondary battery, and power device comprising the same. 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0062] 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.

[0063] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0064] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0065] 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.

[0066] 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.

[0067] 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).

[0068] In this document, substituents of compounds are disclosed by groups or ranges. It is expressly anticipated that such descriptions include each individual subcombination of members of these groups and ranges. For example, it is expressly anticipated that the term “C1-C8 alkyl” individually discloses C1, C2, C3, C4, C5, C6, C7, C8, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C8, C4-C7, C4-C6, C4-C5, C5-C8, C5-C7, C5-C6, C6-C8, C6-C7, and C7-C8 alkyl groups.

[0069] In this document, the term "aliphatic hydrocarbon group" includes alkyl, alkenyl, and alkynyl groups, and the term "heteroaliphatic hydrocarbon group" refers to an aliphatic hydrocarbon group containing heteroatoms (e.g., N, O, S, etc.). The term "heteroalkyl group" refers to an alkyl group containing heteroatoms (e.g., N, O, S, etc.), such as alkoxy, alkylthio, etc.

[0070] In this article, the terms "multiple" or "various" refer to two or more kinds.

[0071] In this article, “about” refers to a range of values, specifically within ±10% of that value.

[0072] The inventors of this application discovered in practical operation that manganese ion dissolution is severe in lithium manganese phosphate (LiMnPO4) positive electrode active materials during deep charge-discharge processes. Although existing technologies have attempted to coat lithium manganese phosphate with lithium iron phosphate to reduce interfacial side reactions, this coating cannot prevent the dissolved manganese ions from migrating into the electrolyte. After migrating to the negative electrode, the dissolved manganese ions are reduced to metallic manganese. This generated metallic manganese acts as a "catalyst," catalyzing the decomposition of the SEI (solid electrolyte interphase) film on the negative electrode surface. Some of the byproducts are gases, which can easily cause battery expansion and affect battery safety performance; others deposit on the negative electrode surface, hindering the channels for lithium ions to enter and exit the negative electrode, increasing battery impedance and affecting battery kinetic performance. Furthermore, to replenish the lost SEI film, the electrolyte and active lithium ions inside the battery are continuously consumed, thus irreversibly affecting the battery's capacity retention rate.

[0073] The inventors of this application repeatedly studied the effects of doping various elements at the Li, Mn, P, and O sites of lithium manganese phosphate, and discovered that by simultaneously doping specific elements in specific amounts at the above four sites, improved lithium manganese phosphate cathode active materials can be obtained. Furthermore, the inventors of this application found that using the improved lithium manganese phosphate cathode active material in combination with organopolysiloxane compounds can alleviate the erosion of the improved lithium manganese phosphate cathode active material surface by the electrolyte, thereby facilitating the full utilization of the improved lithium manganese phosphate cathode active material's electrochemical performance.

[0074] Positive electrode material composition

[0075] Specifically, the first aspect of this application provides a positive electrode material composition comprising a positive electrode active material and an organopolysiloxane compound.

[0076] The positive electrode active material has the chemical formula Li a A x Mn 1-y B y P1-z C z O 4-n D n 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 (boron), 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.

[0077] 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.

[0078] The positive electrode active material of this application is obtained by elemental doping of the compound LiMnPO4, where A, B, C, and D are the elements doped at the Li, Mn, P, and O sites of 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 can also effectively reduce surface activity, thereby suppressing manganese ion dissolution and interfacial side reactions between the positive electrode active material and the electrolyte. P-site doping makes the Mn-O bond length change rate faster, reducing the small polaron migration barrier of the material, which is beneficial to improving electronic conductivity. O-site doping has a good effect on reducing interfacial side reactions. P-site and O-site doping also affect the manganese ion dissolution and kinetics of antisite defects.

[0079] Therefore, doping reduces the concentration of antisite defects in the positive electrode active material, improves the kinetic performance and specific capacity of the positive electrode active material, and can also change the morphology of the particles, thereby increasing the compaction density. The inventors of this application unexpectedly discovered that by simultaneously doping specific elements in specific amounts at the Li, Mn, P, and O sites of the compound LiMnPO4, improved rate performance can be obtained, while reducing the dissolution of Mn and Mn-site dopants, resulting in improved cycle performance and / or high-temperature stability. Furthermore, the specific capacity and compaction density of the positive electrode active material can also be increased. 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.

[0080] The cathode material composition of this application comprises a cathode active material and an organopolysiloxane compound. The inventors of this application have discovered that using the aforementioned cathode active material in combination with the organopolysiloxane compound can alleviate the erosion of the cathode active material surface by the electrolyte and reduce the dissolution of Mn and Mn-site dopants, thereby improving the electrochemical performance of the cathode active material. A possible reason is that the Si-O framework of the organopolysiloxane compound can remove F-containing ions from the electrolyte, thereby reducing the electrolyte acidity and alleviating the erosion of the cathode active material surface by acidic substances in the electrolyte; the organopolysiloxane compound also has a certain degree of hydrophobicity, and when it is prepared together with the cathode active material into a cathode electrode sheet, the contact angle between the resulting cathode electrode sheet and the electrolyte increases, thereby alleviating the erosion of the cathode active material surface by the electrolyte.

[0081] Therefore, positive electrode sheets and electrical devices such as secondary batteries using the positive electrode material composition of this application can have high energy density, while also having improved rate performance, cycle performance and / or high temperature stability.

[0082] It should be noted that, by comparing the XRD spectra before and after LiMnPO4 doping in this application, it was found that the positions of the main characteristic peaks of the positive electrode active material in this application are basically the same as those of the material before LiMnPO4 doping. This indicates that the doped lithium manganese phosphate positive electrode active material in this application does not have impurity phases, and the improvement in battery performance mainly comes from element doping, rather than impurity phases.

[0083] In some embodiments, A, C, and D are each independently any one element within their respective ranges, and B is at least two elements within that range. This allows for easier and more accurate control of the composition of the positive electrode active material.

[0084] Optionally, A is any element selected from Mg and Nb.

[0085] Optionally, B is at least two elements selected from Fe, Ti, V, Co and Mg, or alternatively, Fe and one or more elements selected from Ti, V, Co and Mg.

[0086] Optionally, C is S.

[0087] Optionally, D is F.

[0088] 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 improving the rate performance of the battery. Similarly, selecting doping elements at the Mn sites within the aforementioned range can further increase electronic conductivity and reduce the lattice change rate, thus enhancing the rate performance and energy density of the battery. Selecting doping elements at the P sites within the aforementioned range can further improve the rate performance of the battery. Finally, selecting doping elements at the O sites within the aforementioned range can further mitigate interfacial side reactions and improve the high-temperature stability of the battery.

[0089] The value '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, and 1.01. In some embodiments, the value 'a' is selected from the range of 0.97 to 1.01.

[0090] The x is selected from the range of 0.001 to 0.1, for example, 0.001 or 0.005.

[0091] The value of y is selected from the range of 0.001 to 0.5, for example, 0.001, 0.005, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.34, 0.345, 0.349, 0.35, 0.4.

[0092] The z is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1.

[0093] The n is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1.

[0094] In some implementations, x is selected from the range of 0.001 to 0.005.

[0095] In some implementations, y is selected from the range of 0.01 to 0.5, and optionally from the range of 0.25 to 0.5.

[0096] In some implementations, z is selected from the range of 0.001 to 0.005.

[0097] In some implementations, n is selected from the range of 0.001 to 0.005.

[0098] By selecting the x-value within the above range, the kinetic performance of the cathode active material can be further improved. By selecting the y-value within the above range, the specific capacity and rate performance of the cathode active material can be further improved. By selecting the z-value within the above range, the rate performance of the battery can be further improved. By selecting the n-value within the above range, the high-temperature stability of the battery can be further improved.

[0099] In some embodiments, the positive electrode active material satisfies (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 battery can be further improved.

[0100] In some embodiments, the surface of the positive electrode active material is further coated with carbon. This can improve the conductivity of the positive electrode active material.

[0101] 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 battery. The lattice change rate can be measured using methods known in the art, such as X-ray diffraction (XRD).

[0102] 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.

[0103] In some embodiments, the surface oxygen valence state of the positive electrode active material is below -1.82, optionally from -1.89 to -1.98. Lowering the surface oxygen valence state can mitigate interfacial side reactions between the positive electrode active material and the electrolyte, thereby improving the battery's cycle performance and high-temperature stability. The surface oxygen valence state can be measured using methods known in the art, such as electron energy loss spectroscopy (EELS).

[0104] In some embodiments, the compaction density of the positive electrode active material at 3 tons is 2.0 g / cm³. 3 The above is optional, 2.2 g / cm³. 3 In conclusion, higher compaction density results in a greater weight of positive electrode active material per unit volume, thus increasing compaction density is beneficial for improving the volumetric energy density of the battery. Compaction density can be measured according to GB / T 24533-2009.

[0105] In some embodiments, the organopolysiloxane compound comprises at least one structural unit represented by Formula 1.

[0106]

[0107] R1 and R2 independently represent H or at least one of the following functional groups: -COOH, -OH, -SH, -CN, -SCN, amino, phosphate ester, carboxylic acid ester, amide, aldehyde, sulfonyl, polyether segment, C1-C20 aliphatic hydrocarbon, C1-C20 halogenated aliphatic hydrocarbon, C1-C20 heteroaliphatic hydrocarbon, C1-C20 halogenated heteroaliphatic hydrocarbon, C6-C20 aromatic hydrocarbon, C6-C20 halogenated aromatic hydrocarbon, C2-C20 heteroaromatic hydrocarbon, C2-C20 halogenated heteroaromatic hydrocarbon. Optionally, R1 and R2 each independently represent H or at least one of the following functional groups: -COOH, -OH, -SH, amino, phosphate ester, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, phenyl. More preferably, R1 and R2 each independently represent H or at least one of the following functional groups: -OH, -SH, amino, phosphate ester, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl.

[0108] These functional groups can complex manganese ions and / or react with acidic substances in the electrolyte, thereby reducing the dissolution of Mn and Mn-doped elements, and further improving the battery's cycle performance and / or high-temperature stability.

[0109] When these functional groups also have electron-withdrawing properties, the Si in the Si-O framework of the organopolysiloxane compound becomes more electron-deficient, which can further enhance the affinity with F-containing ions in the electrolyte, further alleviate the erosion of the positive electrode active material surface by acidic substances in the electrolyte, reduce the dissolution of Mn and Mn-site dopants, and thus significantly improve the cycle performance and / or high-temperature stability of the battery.

[0110] In some embodiments, the organopolysiloxane compound includes one or more selected from linear polysiloxanes and cyclic polysiloxanes. Optionally, the organopolysiloxane compound is selected from linear polysiloxanes.

[0111] Therefore, this can further alleviate the erosion of the positive electrode active material surface by acidic substances in the electrolyte, reduce the dissolution of Mn and Mn-site dopants, and thus significantly improve the battery's cycle performance and storage performance. Because the electrons in the ring structure of cyclic polysiloxanes have a certain degree of delocalization, compared with linear polysiloxanes, their Si-O framework has a lower affinity for electron-rich F-containing ions, resulting in a slightly lower removal rate of F-containing ions in the electrolyte, a slightly weaker effect in reducing the dissolution of Mn and Mn-site dopants, and a slightly poorer improvement effect on battery cycle performance.

[0112] In some embodiments, the linear polysiloxane may further comprise end-capping groups. Optionally, the end-capping groups comprise at least one of the following functional groups: polyether, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, C6-C20 aromatic hydrocarbon, C1-C8 alkoxy, C2-C8 epoxy, hydroxyl, C1-C8 hydroxyalkyl, amino, C1-C8 aminoalkyl, carboxyl, and C1-C8 carboxyalkyl.

[0113] In some embodiments, the molecular formula of the cyclic polysiloxane may be as shown in Formula 2, where m represents the degree of polymerization of the structural unit shown in Formula 1. Optionally, m ≤ 12, m ≤ 11, m ≤ 10, m ≤ 9, or m ≤ 8.

[0114]

[0115] As an example, the linear polysiloxanes include, but are not limited to, one or more of the following: polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrosiloxane, carboxyl-functionalized polysiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, mercaptopropylpolysiloxane, aminoethylaminopropylpolydimethylsiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, epoxy-terminated polysiloxane, hydroxyl-terminated polydimethylsiloxane, polyether-terminated polydimethylsiloxane, side-chain aminopropylpolysiloxane, side-chain hydroxymethylpolysiloxane, side-chain hydroxypropylpolysiloxane, side-chain polyether-grafted polydimethylsiloxane, and side-chain phosphate-grafted polydimethylsiloxane.

[0116] Optionally, the linear polysiloxane includes one or more of polydimethylsiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, mercaptopropyl polysiloxane, aminoethylaminopropyl polydimethylsiloxane, hydroxyl-terminated polydimethylsiloxane, end-group polyether polydimethylsiloxane, and side-chain phosphate-grafted polydimethylsiloxane.

[0117] As an example, the cyclic polysiloxanes include, but are not limited to, one or more of cyclic polydimethylsiloxane, cyclic polymethylvinylsiloxane, cyclic polymethylhydrosiloxane, and cyclic polymethyltrifluoropropylsiloxane.

[0118] Optionally, the cyclic polysiloxane comprises one or more of the following: 1,3,5,7-octamethylcyclotetrasiloxane, 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, cyclopentadimethylsiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, hexadecylcyclooctasiloxane, and tetradecylcycloheptasiloxane.

[0119] In some embodiments, the number average molecular weight of the organopolysiloxane compound is below 300,000, for example, it can be 400 to 300,000, 400 to 200,000, 400 to 100,000, 400 to 80,000, 400 to 50,000, 400 to 20,000, 400 to 10,000, 1,000 to 100,000, 1,000 to 50,000, 1,000 to 20,000, or 1,000 to 10,000. The number average molecular weight of the organopolysiloxane compound can be determined by methods known in the art, such as gel permeation chromatography (GPC). The testing instrument can be a PL-GPC 220 high-temperature gel permeation chromatograph. In this application, "organopolysiloxane compound" can be either an oligomer or a polymer.

[0120] When the number-average molecular weight of organopolysiloxane compounds is within a suitable range, the battery can simultaneously achieve good kinetic performance and high-temperature stability. This effectively avoids the following situations: if the number-average molecular weight of the organopolysiloxane compound is too low, its hydrophobicity may be poor, which may prevent the effective increase of the contact angle between the positive electrode film and the electrolyte, and thus may not effectively mitigate the erosion of the positive electrode active material surface by the electrolyte, resulting in a potentially insignificant improvement in battery cycle performance and / or high-temperature stability; if the number-average molecular weight of the organopolysiloxane compound is too high, its hydrophobicity may be too strong, which may also be detrimental to slurry dispersion, thereby affecting the improvement of battery performance.

[0121] In some embodiments, the mass percentage of polar functional groups in the organopolysiloxane compound is α, where 0 ≤ α < 50%. Optionally, 5% ≤ α ≤ 30%.

[0122] In this application, "the mass percentage of polar functional groups in the organopolysiloxane compound" refers to the mass proportion of polar functional groups in R1, R2, and the end-capping group in the organopolysiloxane compound. In this application, polar functional groups include one or more of the following: -COOH, -OH, -SH, -CN, -SCN, amino groups (including -NH2, -NH-), phosphate ester groups, carboxylic ester groups (-COO-), amide groups (-CONH-), aldehyde groups (-CHO), sulfonyl groups (-S(=O)2-), polyether segments, halogen atoms, alkoxy groups, and epoxy groups. When the aforementioned polar functional groups are directly connected to silicon atoms, α represents the mass fraction of these polar functional groups in the organopolysiloxane compound. When the aforementioned polar functional groups are not directly connected to silicon atoms, α represents the sum of the mass fractions of the polar functional groups and the divalent to tetravalent methyl groups (e.g., -CH2, -CH-, -C-, etc.) directly connected to them in the organopolysiloxane compound. Here, "divalent to tetravalent methyl groups" refers to the carbon atom directly connected to the polar functional group and located between the polar functional group and the silicon atom, as well as other nonpolar functional groups connected to the carbon atom. Taking polymethyltrifluoropropylsiloxane as an example, α refers to the mass percentage of -CF3, excluding the ethylidene; taking polymethylchloropropylsiloxane as an example, α refers to the mass percentage of -CH2Cl, excluding the ethylidene; taking hydroxypropyl-terminated polydimethylsiloxane as an example, α refers to the mass percentage of -CH2OH. The mass percentage of polar functional groups in organopolysiloxane compounds can be determined by methods known in the art, such as titration (e.g., acid-base titration, redox titration, precipitation titration), infrared spectroscopy, and nuclear magnetic resonance spectroscopy.

[0123] When the content of polar functional groups in organopolysiloxane compounds is within a suitable range, their effect on reducing electrolyte acidity and removing fluoride ions from the electrolyte is better. This can better alleviate the corrosion of the positive electrode active material surface by acidic substances in the electrolyte, and better improve the battery's cycle performance and / or high-temperature stability. It also effectively avoids the following situation: when the content of polar functional groups in organopolysiloxane compounds is too high, their effect on reducing electrolyte acidity and removing fluoride ions from the electrolyte will not be further enhanced, but may lead to a smaller contact angle between the positive electrode film and the electrolyte, resulting in a less significant improvement in battery cycle performance and / or high-temperature stability.

[0124] In some embodiments, the content of the organopolysiloxane compound is from 0.01% to 2% by weight, optionally from 0.1% to 2% by weight, based on the total weight of the cathode material composition. When the content of the organopolysiloxane compound is within a suitable range, it has a better effect on reducing electrolyte acidity and removing F-containing ions from the electrolyte, thereby better mitigating the corrosion of the cathode active material surface by acidic substances in the electrolyte, and better improving the battery's cycle performance and / or high-temperature stability. It can also effectively avoid the following situations: when the content of the organopolysiloxane compound is too high, it may affect the electrolyte wettability of the cathode film layer, affecting the battery's kinetic performance. Furthermore, since the organopolysiloxane compound does not provide capacity, a high content will also reduce the battery's energy density; when the content of the organopolysiloxane compound is too low, its effect on reducing electrolyte acidity and removing F-containing ions from the electrolyte is not significant, and it cannot effectively mitigate the corrosion of the cathode active material surface by acidic substances in the electrolyte, thus the improvement effect on battery cycle performance and / or high-temperature stability may be insignificant.

[0125] In some embodiments, the cathode material composition may further include a binder. The binder may be a substance known in the art that provides a binding effect; optionally, the binder includes at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. Optionally, the binder content is from 1.79% to 10% by weight, or optionally from 2% to 5% by weight, based on the total weight of the cathode material composition.

[0126] In some embodiments, the cathode material composition may further comprise a conductive agent. The conductive agent may be a substance known in the art capable of electron conduction. Optionally, the cathode conductive agent includes at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Optionally, the content of the conductive agent is from 0.2% to 10% by weight, and optionally from 0.5% to 5% by weight, based on the total weight of the cathode material composition.

[0127] In some embodiments, the powder resistivity of the cathode material composition at 12 MPa is 4 Ω / cm to 50 Ω / cm, optionally 4 Ω / cm to 40 Ω / cm. Adjusting the powder resistivity of the cathode material composition within a suitable range can improve the battery's kinetic performance. The powder resistivity of the cathode material composition can be determined by methods known in the art. For example, it can be tested using a powder resistivity tester, referring to GB / T 30835-2014. An exemplary testing method includes the steps of: weighing a certain amount of the sample powder to be tested and placing it in a special mold, setting the test pressure, and thus obtaining the powder resistivity at different pressures. In this application, the test pressure can be set to 12 MPa. The testing instrument can be a Suzhou Jinglü ST2722-SZ type four-probe powder resistivity tester.

[0128] In some embodiments, the specific surface area of ​​the cathode material composition is 8 m². 2 / g to 20m 2 / g, optionally 8m 2 / g to 15m 2 / g. Adjusting the specific surface area of ​​the cathode material composition within a suitable range can reduce interfacial side reactions between the cathode electrode and the electrolyte, decrease battery volume expansion, and thus improve the battery's electrochemical performance. The specific surface area of ​​the cathode material composition can be determined by methods known in the art. For example, it can be measured using the nitrogen adsorption specific surface area analysis method according to GB / T19587-2017, and calculated using the BET (Brunauer-Emmett-Teller) method. The nitrogen adsorption specific surface area analysis can be performed using a Tri-Star 3020 specific surface area and pore size analyzer from Micromeritics, USA.

[0129] Preparation method

[0130] The second aspect of this application relates to a method for preparing the cathode material composition of the first aspect of this application, comprising the following steps: (1) dissolving and stirring a manganese source, a source of element B and an acid in a solvent to generate a suspension of manganese salt doped with element B, filtering the suspension and drying the filter cake to obtain manganese salt doped with element B; (2) adding a lithium source, a phosphorus source, a source of element A, a source of element C and a source of element D, a solvent and the manganese salt doped with element B obtained in step (1) into a reaction vessel for grinding and mixing to obtain a slurry; (3) transferring the slurry obtained in step (2) to a spray drying device for spray drying and granulation to obtain particles; (4) sintering the particles obtained in step (3) to obtain a cathode active material; (5) mixing the cathode active material obtained in step (4) with an organopolysiloxane compound, an optional binder and an optional conductive agent to obtain a cathode material composition.

[0131] 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 performance of the positive electrode active material.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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).

[0138] In some embodiments, the stirring in step (1) is carried out at a temperature in the range of 60-120°C. In some embodiments, the stirring in step (1) is carried out at a stirring rate of 200-800 rpm, 300-800 rpm, or 400-800 rpm. In some embodiments, the stirring in step (1) is carried out for 6-12 hours. In some embodiments, the grinding and mixing in step (2) is carried out for 8-15 hours.

[0139] 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 specific capacity and rate performance of the positive electrode active material.

[0140] In some implementations, the filter cake may be washed before drying in step (1).

[0141] 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 120-300°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 50-200 nm. Median particle size Dv 50 This refers to the particle size corresponding to a cumulative volume distribution percentage of the material reaching 50%. In this application, the median particle size Dv of the 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., MalvernMaster Size 3000) can be used for determination.

[0142] 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 more combinations 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 range of 0.1%-5%. The grinding can be performed by a suitable grinding method known in the art, for example, by sand milling.

[0143] In some embodiments, the temperature and time of spray drying in step (3) can be the temperature and time conventional for spray drying in the art, for example, 1-6 hours at 100-300°C.

[0144] In some embodiments, sintering in step (4) is carried out at a temperature range of 600-900°C for 6-14 hours. By controlling the sintering temperature and time, the crystallinity of the positive electrode active material can be controlled, and the amount of Mn and Mn-site doped elements dissolved after cycling can be reduced, thereby improving the high-temperature stability and cycle performance of the battery.

[0145] In some embodiments, sintering in step (4) is carried out under a protective atmosphere, which may be nitrogen, an inert gas, hydrogen, or a mixture thereof.

[0146] Positive electrode sheet

[0147] 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 surface of the positive current collector, the positive electrode film layer comprising a positive electrode material composition of the first aspect of this application or a positive electrode material composition prepared by the method of the second aspect of this application, and the content of the positive electrode material composition in the positive electrode film layer is 50% by weight or more, based on the total weight of the positive electrode film layer.

[0148] The positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0149] In some embodiments, the positive electrode material composition may optionally be present in the positive electrode film layer at a content of 90% to 100% by weight, based on the total weight of the positive electrode film layer.

[0150] The positive electrode film layer does not exclude components other than the positive electrode material composition of the first aspect of this application or the positive electrode material composition prepared by the method of the second aspect of this application. For example, the positive electrode film layer may also include other positive electrode active materials besides the positive electrode active materials mentioned above in this application. Optionally, the other positive electrode active materials may include at least one of lithium transition metal oxides and their modified compounds. As an example, the other positive electrode active materials may include at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.

[0151] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. As an example, the metal material may be selected from at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer substrate may be selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0152] In some embodiments, the solid-liquid contact angle between the positive electrode film and the non-aqueous organic solvent is between 3° and 90°, optionally between 3° and 60°, and further between 10° and 30°. When the contact angle is within a suitable range, the battery can simultaneously achieve high energy density, good rate performance, cycle performance, and high-temperature stability. It also effectively avoids the following situations: if the contact angle is too small, it cannot effectively alleviate the erosion of the positive electrode active material surface by acidic substances in the electrolyte, and its effect on improving cycle performance may not be significant; if the contact angle is too large, it may cause poor electrolyte wettability of the positive electrode film, affecting the battery's rate performance and cycle performance. The solid-liquid contact angle between the positive electrode film and the non-aqueous organic solvent has a well-known meaning in the art and can be tested using methods known in the art, such as referring to GB / T 30693-2014 for measurement. An exemplary test method includes the following steps: at room temperature, drop a non-aqueous organic solvent onto the surface of the positive electrode sheet, and measure its contact angle within 60 seconds using a contact angle measuring instrument. The testing instrument can be a LSA 200 optical contact angle measuring instrument from LAUDAS Scientific, Germany. The non-aqueous organic solvent can be any non-aqueous organic solvent known in the art for use in non-aqueous electrolytes for secondary batteries; optionally, the non-aqueous organic solvent is ethylene carbonate (EC).

[0153] In some embodiments, the porosity of the positive electrode film is 15% to 50%, optionally 20% to 40%. When the porosity is within a suitable range, the battery can simultaneously achieve high energy density, good rate performance, cycle performance, and high-temperature stability. It also effectively avoids the following situations: if the porosity is too low, the electrolyte wettability of the positive electrode film may deteriorate, affecting the battery's rate performance and cycle performance; if the porosity is too high, it may affect the overall energy density of the battery. The porosity of the positive electrode film has a well-known meaning in the art and can be tested using methods known in the art, such as by peeling off the positive electrode film with tape and measuring it according to GB / T 24586-2009. Porosity P = [(V2-V1) / V2] × 100%. V1(em 3V² (cm²) represents the true volume, which can be determined using an inert gas with a small molecular diameter (such as helium) via a displacement method, combined with Archimedes' principle and Bohr's law. 3 V represents the apparent volume, V² = S × H × A, where S (cm²) 2 ) represents the area, H (cm) represents the thickness, and A represents the number of samples.

[0154] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous. The solvent may be N-methylpyrrolidone (NMP), but is not limited to this.

[0155] It should be noted that the parameters of each positive electrode film layer (such as contact angle, porosity, etc.) given in this application refer to the parameters of the positive electrode film layer on one side of the positive electrode current collector. When the positive electrode film layer is disposed on both sides of the positive electrode current collector, if the parameters of the positive electrode film layer on either side meet the requirements of this application, it is considered to fall within the protection scope of this application.

[0156] Furthermore, the aforementioned tests on the parameters of the positive electrode film can be performed by sampling during the preparation of the positive electrode sheet or battery, or by sampling from a prepared battery. As an example, when the test samples are taken from a prepared battery, the sampling can be performed as follows: Discharge the battery (for safety, the battery is generally kept fully discharged); remove the positive electrode sheet after disassembling the battery, and soak it in dimethyl carbonate (DMC) for a certain period of time (e.g., 2-10 hours); then remove the positive electrode sheet and dry it at a certain temperature and time (e.g., 60°C, 4 hours). After drying, remove the positive electrode sheet, and then samples can be taken from the dried positive electrode sheet to test the parameters related to the positive electrode film described above.

[0157] Secondary batteries

[0158] A fourth aspect of this application provides a secondary battery that includes the positive electrode of the third aspect of this application.

[0159] A secondary battery, also known as a rechargeable battery or accumulator, is a battery that can be recharged after discharge to reactivate its active materials and continue to be used. Typically, a secondary battery consists of an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator is positioned between the positive and negative electrodes, primarily preventing short circuits while allowing active ions to pass through. The electrolyte, located between the positive and negative electrodes, conducts the active ions.

[0160] [Positive electrode plate]

[0161] The positive electrode used in the secondary battery of this application is the positive electrode described in any embodiment of the third aspect of this application.

[0162] [Negative electrode plate]

[0163] In some embodiments, 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 and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0164] The negative electrode active material may be any negative electrode active material known in the art for use in secondary batteries. As an example, the negative electrode active material includes, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy. This application is not limited to these materials, and other conventionally known materials that can be used as negative electrode active materials for secondary batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0165] In some embodiments, the negative electrode film may optionally include a negative electrode conductive agent. This application does not impose any particular limitation on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0166] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. This application does not impose any particular limitation on the type of negative electrode binder. As an example, the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0167] In some embodiments, the negative electrode film may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0168] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymer base material and a metal material layer formed on at least one surface of the polymer base material. As an example, the metal material may be selected from at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer base material may be selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0169] The negative electrode film layer is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is typically formed by dispersing a negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0170] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of this application further includes a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of this application further includes a protective layer covering the surface of the negative electrode film layer.

[0171] [Electrolytes]

[0172] This application does not impose specific limitations on the type of electrolyte, which can be selected according to requirements. For example, the electrolyte can be selected from at least one of solid electrolytes and liquid electrolytes (i.e., electrolyte solutions).

[0173] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0174] The type of electrolyte salt is not specifically limited and can be selected according to actual needs. In some embodiments, as an example, the electrolyte salt may include at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0175] The type of solvent is not specifically limited and can be selected according to actual needs. In some embodiments, as an example, the solvent may include at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0176] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0177] [Isolation membrane]

[0178] Secondary batteries using electrolytes, as well as some secondary batteries using solid electrolytes, also include a separator. The separator is disposed between the positive and negative electrodes, primarily serving to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through. 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.

[0179] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0180] In some embodiments, the positive electrode, the separator, and the negative electrode can be fabricated into an electrode assembly using a winding process and / or a stacking process.

[0181] In some embodiments, the secondary battery may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0182] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0183] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. Figure 1 This is an example of a square-structured secondary battery 5.

[0184] In some implementations, such as Figure 2 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 52 by a winding process and / or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be adjusted according to requirements.

[0185] The method for preparing the secondary battery described in this application is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a secondary battery. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding or stacking process. The electrode assembly is then placed in an outer package, dried, and injected with an electrolyte. After vacuum sealing, settling, formation, and shaping processes, a secondary battery is obtained.

[0186] In some embodiments of this application, the secondary battery according to this application can be assembled into a battery module. The number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0187] Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3 As shown, in battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

[0188] Optionally, the battery module 4 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0189] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0190] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3. The upper body 2 covers the lower body 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0191] Electrical appliances

[0192] The fifth aspect of this application provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack described in this application. The secondary battery, battery module, or battery pack 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 be, 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.

[0193] The electrical device can be equipped with a secondary battery, battery module, or battery pack according to its usage requirements.

[0194] Figure 6 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0195] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use rechargeable batteries as their power source.

[0196] Example

[0197] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0198] Example 1

[0199] 1) Preparation of positive electrode active materials

[0200] Preparation of doped manganese oxalate: 1.3 mol of MnSO4·H2O and 0.7 mol of FeSO4·H2O were thoroughly mixed in a mixer for 6 hours. The mixture was transferred to a reaction vessel, and 10 L of deionized water and 2 mol of oxalic acid dihydrate (calculated as oxalic acid) were added. The reaction vessel was heated to 80 °C and stirred at 600 rpm for 6 hours until the reaction was terminated (no more bubbles were generated), yielding a Fe-doped manganese oxalate suspension. The suspension was then filtered, and the filter cake was dried at 120 °C and then ground to obtain a median particle size Dv. 50 The particles are Fe-doped manganese oxalate particles with a diameter of approximately 100 nm.

[0201] 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 thoroughly ground and stirred for 10 hours to obtain a slurry. The slurry was then transferred to a spray drying equipment for spray drying granulation. The drying temperature was set at 250°C and the drying time was 4 hours to obtain granules. Under a protective atmosphere of nitrogen (90 vol%) + hydrogen (10 vol%), the above 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 This refers to the positive electrode active material. The elemental content can be detected using inductively coupled plasma atomic emission spectroscopy (ICP).

[0202] 2) Preparation of button cells

[0203] A positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α approximately 12%, number average molecular weight 3700) were mixed in a mixer at a weight ratio of 89.4:5:5:0.6 until the materials were uniformly mixed to obtain a positive electrode material composition. Then, the above positive electrode material composition was added to N-methylpyrrolidone (NMP) and stirred in a drying chamber to form a slurry. The slurry was coated onto aluminum foil, dried, and cold-pressed to form a positive electrode sheet. The coating amount was 0.015 g / cm³. 2 The compacted density is 2.0 g / cm³. 3 .

[0204] A lithium sheet is used as the negative electrode, and a solution of 1 mol / L LiPF6 in ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1 is used as the electrolyte. The lithium sheet and the positive electrode prepared above are assembled into a coin cell in a coin cell box to form a coin cell (hereinafter also referred to as "coin cell").

[0205] 3) Preparation of full cells

[0206] A positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α approximately 12%, number average molecular weight 3700) were mixed in a mixer at a weight ratio of 93.4:1.5:4.5:0.6 until the materials were uniformly mixed to obtain a positive electrode material composition. Then, the above positive electrode material composition was uniformly mixed in an N-methylpyrrolidone solvent system, coated onto aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet. The coating amount was 0.018 g / cm³. 2 The compacted density is 2.4 g / cm³. 3 .

[0207] Artificial graphite (anode active material), hard carbon, acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC) (thickener) were mixed evenly in deionized water at a weight ratio of 90:5:2:2:1. The mixture was then coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet. The coating amount was 0.0075 g / cm³. 2 The compacted density is 1.7 g / cm³. 3 .

[0208] Using a porous polyethylene (PE) polymer film as a separator, the positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The electrode assembly is then wound up. The electrode assembly is placed in an outer package, injected with the same electrolyte as used in the preparation of the coin cell, and sealed to obtain a full cell (hereinafter also referred to as "full cell").

[0209] Examples 2 to 27

[0210] Except for the preparation of the positive electrode active material, the preparation of the coin cell and the full cell are the same as in Example 1.

[0211] Example 2

[0212] 1) Preparation of positive electrode active material: Except for changing the amount of Li2CO3 to 0.4885 mol, replacing Mo(SO4)3 with MgSO4, changing the amount of FeSO4·H2O to 0.68 mol, adding 0.02 mol of Ti(SO4)2 when preparing doped manganese oxalate, and replacing H4SiO4 with HNO3, the rest is the same as in Example 1.

[0213] Example 3

[0214] 1) Preparation of positive electrode active material: Except for changing the amount of Li2CO3 to 0.496mol, replacing Mo(SO4)3 with W(SO4)3, and replacing H4SiO4 with H2SO4, the rest is the same as in Example 1.

[0215] Example 4

[0216] 1) Preparation of positive electrode active material: Except for changing the amount of Li2CO3 to 0.4985 mol, replacing 0.001 mol of Mo(SO4)3 with 0.0005 mol of Al2(SO4)3 and replacing NH4HF2 with NH4HCl2, the rest is the same as in Example 1.

[0217] Example 5

[0218] 1) Preparation of positive electrode active material: Except for changing the amount of FeSO4·H2O to 0.69 mol, adding 0.01 mol of VCl2 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.4965 mol, replacing 0.001 mol of Mo(SO4)3 with 0.0005 mol of Nb2(SO4)5 and replacing H4SiO4 with H2SO4, the rest is the same as in Example 1.

[0219] Example 6

[0220] 1) Preparation of positive electrode active material: Except for changing the amount of FeSO4·H2O to 0.68 mol, adding 0.01 mol of VCl2 and 0.01 mol of MgSO4 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.4965 mol, replacing 0.001 mol of Mo(SO4)3 with 0.0005 mol of Nb2(SO4)5 and replacing H4SiO4 with H2SO4, the rest is the same as in Example 1.

[0221] Example 7

[0222] 1) Preparation of positive electrode active material: Except for replacing MgSO4 with CoSO4, the preparation is the same as in Example 6.

[0223] Example 8

[0224] 1) Preparation of positive electrode active material: Except for replacing MgSO4 with NiSO4, the preparation is the same as in Example 6.

[0225] Example 9

[0226] 1) Preparation of positive electrode active material: Except for changing the amount of FeSO4·H2O to 0.698 mol, adding 0.002 mol of Ti(SO4)2 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.4955 mol, replacing 0.001 mol of Mo(SO4)3 with 0.0005 mol of Nb2(SO4)5, replacing H4SiO4 with H2SO4, and replacing NH4HF2 with NH4HCl2, the rest is the same as in Example 1.

[0227] Example 10

[0228] 1) Preparation of positive electrode active material: Except for changing the amount of FeSO4·H2O to 0.68 mol, adding 0.01 mol of VCl2 and 0.01 mol of MgSO4 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.4975 mol, replacing 0.001 mol of Mo(SO4)3 with 0.0005 mol of Nb2(SO4)5 and replacing NH4HF2 with NH4HBr2, the rest is the same as in Example 1.

[0229] Example 11

[0230] 1) Preparation of positive electrode active materials: In addition to F eThe amount of SO4·H2O was changed to 0.69 mol, and 0.01 mol of VCl2 was added when preparing the doped manganese oxalate. The amount of Li2CO3 was changed to 0.499 mol. Except for replacing Mo(SO4)3 with MgSO4 and NH4HF2 with NH4HBr2, everything else was the same as in Example 1.

[0231] Example 12

[0232] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.36 mol, the amount of FeSO4·H2O to 0.6 mol, adding 0.04 mol of VCl2 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.4985 mol, replacing Mo(SO4)3 with MgSO4 and H4SiO4 with HNO3, the rest is the same as in Example 1.

[0233] Example 13

[0234] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.16 mol and the amount of FeSO4·H2O to 0.8 mol, the rest is the same as in Example 12.

[0235] Example 14

[0236] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.3 mol and the amount of VCl2 to 0.1 mol, the rest is the same as in Example 12.

[0237] Example 15

[0238] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.2 mol, adding 0.1 mol of VCl2 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.494 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, and replacing H4SiO4 with H2SO4, the rest is the same as in Example 1.

[0239] Example 16

[0240] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.2 mol, adding 0.1 mol of VCl2 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.467 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, replacing 0.001 mol of H4SiO4 with 0.005 mol of H2SO4, and replacing 1.175 mol of 85% phosphoric acid with 1.171 mol of 85% phosphoric acid, everything else is the same as in Example 1.

[0241] Example 17

[0242] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.2 mol, adding 0.1 mol of VCl2 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.492 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, replacing H4SiO4 with H2SO4, and changing the amount of NH4HF2 to 0.0025 mol, the rest is the same as in Example 1.

[0243] Example 18

[0244] 1) Preparation of positive electrode active material: Except for changing the amount of FeSO4·H2O to 0.5 mol, adding 0.1 mol of VCl2 and 0.1 mol of CoSO4 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.492 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, replacing H4SiO4 with H2SO4, and changing the amount of NH4HF2 to 0.0025 mol, the rest is the same as in Example 1.

[0245] Example 19

[0246] 1) Preparation of positive electrode active material: Except for changing the amount of FeSO4·H2O to 0.4 mol and the amount of CoSO4 to 0.2 mol, the preparation is the same as in Example 18.

[0247] Example 20

[0248] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.5 mol, the amount of FeSO4·H2O to 0.1 mol, and the amount of CoSO4 to 0.3 mol, the rest is the same as in Example 18.

[0249] Example 21

[0250] 1) Preparation of positive electrode active material: except that 0.1 mol of CoSO4 was replaced with 0.1 mol of NiSO4, the preparation was the same as in Example 18.

[0251] Example 22

[0252] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.5 mol, the amount of FeSO4·H2O to 0.2 mol, and replacing 0.1 mol of CoSO4 with 0.2 mol of NiSO4, the rest is the same as in Example 18.

[0253] Example 23

[0254] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.4 mol, the amount of FeSO4·H2O to 0.3 mol, and the amount of CoSO4 to 0.2 mol, the rest is the same as in Example 18.

[0255] Example 24

[0256] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.2 mol, the amount of FeSO4·H2O to 0.5 mol, adding 0.1 mol of VCl2 and 0.2 mol of CoSO4 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.497 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, replacing H4SiO4 with H2SO4, and changing the amount of NH4HF2 to 0.0025 mol, the rest is the same as in Example 1.

[0257] Example 25

[0258] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.0 mol, the amount of FeSO4·H2O to 0.7 mol, and the amount of CoSO4 to 0.2 mol, the rest is the same as in Example 18.

[0259] Example 26

[0260] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.4 mol, the amount of FeSO4·H2O to 0.3 mol, adding 0.1 mol of VCl2 and 0.2 mol of CoSO4 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.4825 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, changing the amount of H4SiO4 to 0.1 mol, changing the amount of phosphoric acid to 0.9 mol, and changing the amount of NH4HF2 to 0.04 mol, everything else is the same as in Example 1.

[0261] Example 27

[0262] 1) Preparation of positive electrode active material: Except for changing the amount of MnSO4·H2O to 1.4 mol, the amount of FeSO4·H2O to 0.3 mol, adding 0.1 mol of VCl2 and 0.2 mol of CoSO4 when preparing doped manganese oxalate, changing the amount of Li2CO3 to 0.485 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, changing the amount of H4SiO4 to 0.08 mol, changing the amount of phosphoric acid to 0.92 mol, and changing the amount of NH4HF2 to 0.05 mol, the rest is the same as in Example 1.

[0263] Examples 28 to 32

[0264] Except for adjusting the weight percentage of aminoethylaminopropylpolydimethylsiloxane in the cathode material composition in "2) Preparation of button cell" and "3) Preparation of full cell", the rest is the same as in Example 1.

[0265] Example 28

[0266] 2) Preparation of button cells

[0267] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage α of approximately 12%, and a number average molecular weight of 3700) were mixed in a mixer at a weight ratio of 89.99:5:5:0.01 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0268] 3) Preparation of full cells

[0269] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups are -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) are stirred in a mixer at a weight ratio of 93.99:1.5:4.5:0.01 until the materials are uniformly mixed to obtain the positive electrode material composition.

[0270] Example 29

[0271] 2) Preparation of button cells

[0272] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage α of approximately 12%, and a number average molecular weight of 3700) were stirred in a mixer at a weight ratio of 89.9:5:5:0.1 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0273] 3) Preparation of full cells

[0274] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and alkylaminoethylaminopropyl polydimethylsiloxane (polar functional groups are -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) are mixed in a mixer at a weight ratio of 93.9:1.5:4.5:0.1 until the materials are uniformly mixed to obtain the positive electrode material composition.

[0275] Example 30

[0276] 2) Preparation of button cells

[0277] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage α of approximately 12%, and a number average molecular weight of 3700) were stirred in a mixer at a weight ratio of 89:5:5:1 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0278] 3) Preparation of full cells

[0279] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage α of approximately 12%, and a number average molecular weight of 3700) were stirred in a mixer at a weight ratio of 93:1.5:4.5:1 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0280] Example 31

[0281] 2) Preparation of button cells

[0282] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage a of approximately 12%, and a number average molecular weight of 3700) were stirred in a mixer at a weight ratio of 88:5:5:2 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0283] 3) Preparation of full cells

[0284] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage α of approximately 12%, and a number average molecular weight of 3700) were stirred in a mixer at a weight ratio of 92:1.5:4.5:2 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0285] Example 32

[0286] 2) Preparation of button cells

[0287] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage α of approximately 12%, and a number average molecular weight of 3700) were stirred in a mixer at a weight ratio of 86:5:5:4 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0288] 3) Preparation of full cells

[0289] The positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF), and aminoethylaminopropyl polydimethylsiloxane (with polar functional groups -CH2NH2 and -CH2NH-, a mass percentage α of approximately 12%, and a number average molecular weight of 3700) were stirred in a mixer at a weight ratio of 90:1.5:4.5:4 until the materials were uniformly mixed to obtain the positive electrode material composition.

[0290] Examples 33 to 50

[0291] Except for replacing the aminoethylaminopropylpolydimethylsiloxane in the cathode material composition with the following organopolysiloxane compounds in “2) Preparation of button cell” and “3) Preparation of full cell”, the rest is the same as in Example 1.

[0292] Example 33: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 1200).

[0293] Example 34: Polymethylchloropropylsiloxane (polar functional group is -CH2Cl, mass percentage α is about 30.2%, number average molecular weight is 2500).

[0294] Example 35: Polymethyltrifluoropropylsiloxane (polar functional group is -CF3, mass percentage α is about 44.0%, number average molecular weight is 1400).

[0295] Example 36: Mercaptopropyl polysiloxane (polar functional group is -CH2SH, mass percentage α is about 15.0%, number average molecular weight is 2000).

[0296] Example 37: Hydroxyl-terminated polydimethylsiloxane (polar functional group is -OH, mass percentage α is about 3.4%, number average molecular weight is 1000).

[0297] Example 38: Methoxy-terminated polydimethylsiloxane (the polar functional group is methoxy, the mass percentage α is about 3.1%, and the number average molecular weight is 2800).

[0298] Example 39: Terminal polyether polydimethylsiloxane (polar functional group is polyether segment, mass percentage α is about 10.0%, number average molecular weight is 2110).

[0299] Example 40: Side-chain phosphate ester grafted polydimethylsiloxane (polar functional group is phosphate ester group, mass percentage α is about 1.4%, number average molecular weight is 15600),

[0300] Example 41: 1,3,5,7-octamethylcyclotetrasiloxane (mass percentage of polar functional groups α is about 0%, molecular weight is 280).

[0301] Example 42: Cyclopentadimethylsiloxane (mass percentage of polar functional groups α is about 0%, molecular weight is 370).

[0302] Example 43: Terminal polyether polydimethylsiloxane (polar functional group is polyether segment, mass percentage α is about 55.0%, number average molecular weight is 25132).

[0303] Example 44: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 400).

[0304] Example 45: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 10,000).

[0305] Example 46: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 50,000).

[0306] Example 47: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 80,000).

[0307] Example 48: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 100,000).

[0308] Example 49: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 300,000).

[0309] Example 50: Polydimethylsiloxane (the mass percentage of polar functional groups α is about 0%, and the number average molecular weight is 400,000).

[0310] Comparative Example 1

[0311] 1) Preparation of positive electrode active materials

[0312] Preparation of manganese oxalate: 1 mol of MnSO4·H2O was added to a reaction vessel, along with 10 L of deionized water and 1 mol of oxalic acid dihydrate (calculated as oxalic acid). The reaction vessel was heated to 80°C and stirred at 600 rpm for 6 hours until the reaction was terminated (no more bubbles were generated), yielding a manganese oxalate suspension. The suspension was then filtered, and the filter cake was dried at 120°C and subsequently ground to obtain a median particle size Dv. 50 Manganese oxalate particles with a diameter of 50-200 nm.

[0313] Preparation of lithium manganese phosphate: 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 were added to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. The slurry was then transferred to a spray drying equipment for spray drying granulation. The drying temperature was set at 250 °C, and the granules were dried for 4 hours to obtain particles. Under a protective atmosphere of nitrogen (90 vol%) + hydrogen (10 vol%), the above powder was sintered at 700 °C for 10 hours to obtain carbon-coated LiMnPO4.

[0314] 2) Preparation of button cells

[0315] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0316] 3) Preparation of full cells

[0317] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0318] Comparative Example 2

[0319] 1) Preparation of positive electrode active materials

[0320] 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 the mixture was added to a mixer and thoroughly mixed for 6 hours before being added to the reactor, everything else was the same as in Comparative Example 1.

[0321] 2) Preparation of button cells

[0322] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0323] 3) Preparation of full cells

[0324] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0325] Comparative Example 3

[0326] 1) Preparation of positive electrode active materials

[0327] Except for changing the amount of MnSO4·H2O to 1.9 mol, replacing 0.7 mol of FeSO4·H2O with 0.1 mol of ZnSO4, changing the amount of Li2CO3 to 0.495 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of MgSO4, changing the amount of phosphoric acid to 1 mol, and not adding H4SiO4 and NH4HF2, everything else is the same as in Example 1.

[0328] 2) Preparation of button cells

[0329] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0330] 3) Preparation of full cells

[0331] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0332] Comparative Example 4

[0333] 1) Preparation of positive electrode active materials

[0334] Except for changing the amount of MnSO4·H2O to 1.2 mol, the amount of FeSO4·H2O to 0.8 mol, the amount of Li2CO3 to 0.45 mol, replacing 0.001 mol of Mo(SO4)3 with 0.005 mol of Nb2(SO4)5, changing the amount of phosphoric acid to 1 mol, changing the amount of NH4HF2 to 0.025 mol, and not adding H4SiO4, everything else is the same as in Example 1.

[0335] 2) Preparation of button cells

[0336] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0337] 3) Preparation of full cells

[0338] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0339] Comparative Example 5

[0340] 1) Preparation of positive electrode active materials

[0341] Except for changing the amount of MnSO4·H2O to 1.4 mol, the amount of FeSO4·H2O to 0.6 mol, the amount of Li2CO3 to 0.38 mol, and replacing 0.001 mol of Mo(SO4)3 with 0.12 mol of MgSO4, everything else is the same as in Example 1.

[0342] 2) Preparation of button cells

[0343] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0344] 3) Preparation of full cells

[0345] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0346] Comparative Example 6

[0347] 1) Preparation of positive electrode active materials

[0348] Except for changing the amount of MnSO4·H2O to 0.8 mol, replacing 0.7 mol of FeSO4·H2O with 12 mol of ZnSO4, changing the amount of Li2CO3 to 0.499 mol, and replacing 0.001 mol of Mo(SO4)3 with 0.001 mol of MgSO4, everything else is the same as in Example 1.

[0349] 2) Preparation of button cells

[0350] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0351] 3) Preparation of full cells

[0352] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0353] Comparative Example 7

[0354] 1) Preparation of positive electrode active materials

[0355] Except for changing the amount of MnSO4·H2O to 1.4 mol, FeSO4·H2O to 0.6 mol, Li2CO3 to 0.534 mol, replacing 0.001 mol of Mo(SO4)3 with 0.001 mol of MgSO4, changing the amount of phosphoric acid to 0.88 mol, changing the amount of H4SiO4 to 0.12 mol, and changing the amount of NH4HF2 to 0.025 mol, everything else is the same as in Example 1.

[0356] 2) Preparation of button cells

[0357] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0358] 3) Preparation of full cells

[0359] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0360] Comparative Example 8

[0361] 1) Preparation of positive electrode active materials

[0362] Except for changing the amount of MnSO4·H2O to 1.2 mol, FeSO4·H2O to 0.8 mol, Li2CO3 to 0.474 mol, replacing 0.001 mol of Mo(SO4)3 with 0.001 mol of MgSO4, changing the amount of phosphoric acid to 0.93 mol, changing the amount of H4SiO4 to 0.07 mol, and changing the amount of NH4HF2 to 0.06 mol, everything else is the same as in Example 1.

[0363] 2) Preparation of button cells

[0364] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0365] 3) Preparation of full cells

[0366] Except for the absence of aminoethylaminopropylpolydimethylsiloxane, it is the same as in Example 1.

[0367] Comparative Example 9

[0368] Except for the omission of aminoethylaminopropylpolydimethylsiloxane in “2) Preparation of button cell” and “3) Preparation of full cell”, the process is the same as in Example 1.

[0369] Positive electrode active materials, positive electrode material compositions, positive electrode sheets and battery performance testing methods

[0370] 1. Methods for measuring lattice change rate

[0371] Under a constant temperature environment of 25℃, the positive electrode active material sample was placed in an X-ray diffractometer (model Bruker D8Discover) and tested at a rate of 1° / minute. The test data were then organized and analyzed. Referring to the standard PDF card, the lattice constants a0, b0, c0 and v0 were calculated (a0, b0 and c0 represent the length of the unit cell in each direction, and v0 represents the volume of the unit cell, which can be directly obtained from the XRD refinement results).

[0372] Using the coin cell preparation method described in the above embodiments, the positive electrode active material sample was prepared into a coin cell, and the coin cell was charged at a low rate of 0.05C until the current decreased to 0.01C. Then, the positive electrode sheet of the coin cell was removed and immersed in DMC for 8 hours. After drying, powder was scraped off, and particles with a diameter less than 500nm were screened out. Samples were taken, and their lattice constant v1 was calculated in the same manner as the fresh samples tested above. The lattice change rate before and after complete lithium insertion / extraction is shown in the table, with (v0-v1) / v0×100% representing the lattice change rate before and after complete lithium insertion / extraction.

[0373] 2. Method for measuring the concentration of Li / Mn antisite defects

[0374] The XRD results obtained from the "lattice change rate measurement method" are compared with the PDF (Powder Diffraction File) card of the standard crystal to determine the Li / Mn antisite defect concentration. Specifically, the XRD results obtained from the "lattice change rate measurement method" are imported into the General Structure Analysis System (GSAS) software to automatically obtain refined results, which include the occupancy of different atoms. The Li / Mn antisite defect concentration is then obtained by reading the refined results.

[0375] 3. Methods for measuring surface oxygen valence state

[0376] Five grams of positive electrode active material sample were taken and prepared into a coin cell according to the coin cell preparation method described in the above embodiments. The coin cell was charged at a low rate of 0.05C until the current decreased to 0.01C. Then, the positive electrode sheet of the coin cell was removed and immersed in DMC for 8 hours. Then, it was dried, scraped off, and particles with a particle size of less than 500 nm were screened out. The obtained particles were measured using electron energy loss spectroscopy (EELS, using a Talos F200S instrument) to obtain the energy loss near-edge structure (ELNES), which reflects the density of states and energy level distribution of the element. Based on the density of states and energy level distribution, the number of occupied electrons was calculated by integrating the valence band density of states data, thereby deducing the valence state of the surface oxygen after charging.

[0377] 4. Compacted density measurement method

[0378] Take 5g of positive electrode active material sample powder and place it in a compaction mold (CARVER mold, model 13mm, USA). Then place the mold on a compaction density instrument. Apply a pressure of 3T (tons) and read the powder thickness under pressure (thickness after depressurization; the area of ​​the container used for testing is 1540.25mm²) on the instrument. 2 The compaction density is calculated using p = m / v.

[0379] 5. Powder resistivity test

[0380] A suitable amount of the positive electrode material composition sample powder used to prepare the full battery is placed in a special mold of a powder resistivity tester. The powder resistivity under different pressures is obtained by setting the test pressure. In this application, the test pressure is 12 MPa. The testing instrument is a Suzhou Jinglü ST2722-SZ four-probe powder resistivity tester.

[0381] 6. Specific surface area test

[0382] Five grams of the cathode material composition sample powder used to prepare the full battery were taken, and the specific surface area was measured using a Tri-Star 3020 specific surface area and pore size analyzer from Micromeritics, USA. The specific surface area was calculated using the BET (Brunauer-Emmett-Teller) method.

[0383] 7. Contact Angle Test

[0384] At room temperature, ethylene carbonate (EC) droplets were dropped onto the surface of the positive electrode film, and the solid-liquid contact angle was measured over 60 seconds using an LSA200 optical contact angle meter from LAUDA Scientific, Germany.

[0385] 8. Method for measuring the initial specific capacity of button cells

[0386] Under a constant temperature environment of 25℃, the button cell is charged to 4.3V at 0.1C, and then charged at 4.3V at a constant voltage until the current is less than or equal to 0.05mA. After standing for 5 minutes, it is discharged to 2.0V at 0.1C. The discharge capacity at this time is the initial specific capacity, denoted as D0.

[0387] 9.3C Charging Constant Current Ratio Measurement Method

[0388] Under a constant temperature of 25℃, a fresh full battery is left to stand for 5 minutes, then discharged at 1 / 3C to 2.5V. After standing for 5 minutes, it is charged at 1 / 3C to 4.3V, and then charged at a constant voltage of 4.3V until the current is less than or equal to 0.05mA. After standing for 5 minutes, the charge capacity at this point is recorded as C0. The battery is then discharged at 1 / 3C to 2.5V, left to stand for 5 minutes, and then charged at 3C to 4.3V. After standing for 5 minutes, the charge capacity at this point is recorded as C1. The constant current ratio for 3C charging is C1 / C0 × 100%.

[0389] The higher the constant current ratio during 3C charging, the better the battery's rate performance.

[0390] 10. Full battery gas expansion test at 60°C

[0391] A full battery at 100% state of charge (SOC) was stored at 60°C. The open-circuit voltage (OCV) and internal resistance (IMP) were measured before, during, and after storage to monitor SOC, and the battery volume was also measured. After every 48 hours of storage, the full battery was removed, allowed to stand for 1 hour, and then the OCV and IMP were measured. After cooling to room temperature, the battery volume was measured using the water displacement method. The water displacement method involves first measuring the battery's weight (F1) separately using a balance with automatic unit conversion, and then completely immersing the battery in deionized water (with a known density of 1 g / cm³). 3 In the experiment, the weight F2 of the battery at this moment is measured, and the buoyant force F on the battery is measured. 浮 That is, F1-F2, and then according to Archimedes' principle, F 浮 =ρ×g×V 排 The battery volume V is calculated to be V = (F1 - F2) / (ρ × g).

[0392] Based on the OCV and IMP test results, the battery in this embodiment maintained a state of 99% or higher until the end of the storage process.

[0393] After 30 days of storage, the battery volume was measured, and the percentage increase in battery volume after storage was calculated relative to the battery volume before storage.

[0394] 11. Full battery 45℃ cycle performance test

[0395] Under a constant temperature environment of 45℃, the full battery was charged at 1C to 4.3V, and then charged at a constant voltage of 4.3V until the current was less than or equal to 0.05mA. After resting for 5 minutes, it was discharged at 1C to 2.5V, and the discharge capacity at this point was recorded as E0. This charge-discharge cycle was repeated until the discharge capacity decreased to 80% of E0. The number of cycles completed at this point was recorded.

[0396] 12. Method for measuring the amount of Mn (and Mn-doped Fe) dissolved after cycling

[0397] The full battery, after being cycled at 45°C until its capacity decayed to 80%, was discharged at a 0.1C rate until the cutoff voltage of 2.0V. Then, the battery was disassembled, the negative electrode was removed, and 30 unit areas (1540.25 mm²) were randomly selected from the negative electrode. 2 The discs were tested using an Agilent ICP-OES730 inductively coupled plasma emission spectrometry (ICP). The amounts of Fe (if the Mn site of the positive electrode active material is doped with Fe) and Mn were calculated based on the ICP results, thus determining the amount of Mn (and Mn-doped Fe) dissolved after cycling. The testing standard was based on EPA-6010D-2014.

[0398] 13. Determination of the chemical formula of positive electrode active materials

[0399] High spatial resolution characterization of the internal microstructure and surface structure of the positive electrode active material was performed using spherical aberration electron microscopy (ACSTEM), and the chemical formula of the positive electrode active material was obtained by combining it with three-dimensional reconstruction technology.

[0400] Table 1 shows the composition of the positive electrode active materials of Examples 1-11 and Comparative Examples 1-9.

[0401] Table 2 shows the composition of the positive electrode active materials in Examples 12-27.

[0402] Table 3 shows the types and contents of organopolysiloxane compounds in the cathode material compositions of Examples 1-52.

[0403] Table 4 shows the performance data of the positive electrode active materials, positive electrode material compositions, positive electrode sheets, coin cells or all-electric cells of Examples 1-11 and Comparative Examples 1-9, measured according to the above performance test methods.

[0404] Table 5 shows the performance data of the positive electrode active material, positive electrode material composition, positive electrode sheet, button cell or all-electric cell of Examples 12-27, measured according to the above performance test methods.

[0405] Table 6 shows the performance data of the positive electrode material compositions, positive electrode sheets, coin cells or full cells of Examples 28-50, measured according to the above performance test methods.

[0406] Table 1

[0407]

[0408]

[0409] Table 2

[0410] Serial Number Positive electrode active material (1-y): y a:x Example 12 <![CDATA[Li 0.997 Mg 0.001 Mn 0.68 Fe 0.3 V 0.02 P 0.999 N 0.001 O 3.999 F 0.001 ]]> 2.13 997 Example 13 <![CDATA[Li 0.997 Mg 0.001 Mn 0.58 Fe 0.4 V 0.02 P 0.999 N 0.001 O 3.999 F 0.001 ]]> 1.38 997 Example 14 <![CDATA[Li 0.997 Mg 0.001 Mn 0.65 Fe 0.3 V 0.05 P 0.999 N 0.001 O 3.999 F 0.001 ]]> 1.86 997 Example 15 <![CDATA[Li 0.988 Mg 0.005 Mn 0.6 Fe 0.35 V 0.05 P 0.999 S 0.001 O 3.999 F 0.001 ]]> 1.50 197.6 Example 16 <![CDATA[Li 0.984 Mg 0.005 Mn 0.6 Fe 0.35 V 0.05 P 0.995 S 0.005 O 3.999 F 0.001 ]]> 1.50 196.8 Example 17 <![CDATA[Li 0.984 Mg 0.005 Mn 0.6 Fe 0.35 V 0.05 P 0.999 S 0.001 O 3.995 F 0.005 ]]> 1.50 196.8 Example 18 <![CDATA[Li 0.984 Mg 0.05 Mr 0.65 Feb 0.25 V 0.05 Co 0.05 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 1.86 196.8 Example 19 <![CDATA[Li 0.984 Mg 0.005 Mr 0.65 Feb 0.20 V 0.05 Co 0.10 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 1.86 196.8 Example 20 <![CDATA[Li 0.984 Mg 0.005 Mr 0.75 Feb 0.05 V 0.05 Co 0.15 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 3.00 196.8 Example 21 <![CDATA[Li 0.984 Mg 0.005 Mr 0.65 Feb 0.25 V 0.05 Ni 0.05 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 1.86 196.8 Example 22 <![CDATA[Li 0.984 Mg 0.005 Mr 0.75 Feb 0.10 V 0.05 Ni 0.10 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 3.00 196.8 Example 23 <![CDATA[Li 0.984 Mg 0.005 Mr 0.7 Feb 0.15 V 0.05 Co 0.10 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 2.33 196.8 Example 24 <![CDATA[Li 0.984 Mg 0.005 Mr 0.6 Feb 0.25 V 0.05 Co 0.10 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 1.50 196.8 Example 25 <![CDATA[Li 0.984 Mg 0.005 Mr 0.5 Feb 0.35 V 0.05 Co 0.10 Q 0.999 S 0.001 O 3.995 F 0.005 ]]> 1.00 196.8 Example 26 <![CDATA[Li 1.01 Mg 0.005 Mr 0.7 Feb 0.15 V 0.05 Co 0.10 Q 0.9 Si 0.1 O 3.92 F 0.08 ]]> 2.33 202 Example 27 <![CDATA[Li 0.97 Mg 0.005 Mr 0.7 Feb 0.15 V 0.05 Co 0.10 Q 0.92 Si 0.08 O 3.9 F 0.1 ]]> 2.33 194

[0411] Table 3

[0412]

[0413]

[0414]

[0415]

[0416] As can be seen from Tables 4 and 5 above, each positive electrode active material in the embodiments of this application achieves better performance than the comparative example in one or all aspects of cycle performance, high-temperature stability, specific capacity, and compaction density. By simultaneously doping specific elements at specific amounts at the Li, Mn, P, and O sites of LiMnPO4, improved rate performance can be obtained, while reducing the dissolution of Mn and Fe, resulting in improved cycle performance and / or high-temperature stability. Furthermore, the specific capacity and compaction density of the positive electrode active material can also be increased. When the positive electrode active materials of the embodiments of this application are used in combination with organopolysiloxane compounds, the erosion of the positive electrode active material surface by the electrolyte can be further mitigated, and the dissolution of Mn and Fe can be reduced, thereby further improving the cycle performance of the battery.

[0417] Comparing Examples 18-20 and 23-25, it can be seen that, with other elements being equal, (1-y):y in the range of 1 to 4 can further improve the energy density and cycle performance of the battery.

[0418] Figure 7 The X-ray diffraction (XRD) patterns of undoped LiMnPO4 and the cathode active material prepared in Example 2 are shown. As can be seen from the figure, the main characteristic peak positions in the XRD pattern of the cathode active material of Example 2 are consistent with those of undoped LiMnPO4, indicating that the doping process did not introduce impurity phases, and the performance improvement mainly comes from elemental doping rather than impurity phases. Figure 8 The X-ray energy dispersive spectroscopy (EDS) spectrum of the positive electrode active material prepared in Example 2 is shown. The dots in the spectrum represent the doping elements. The spectrum shows that the positive electrode active material of Example 2 has uniform elemental doping.

[0419] As shown in Table 6 above, when the positive electrode active material is the same, selecting an organopolysiloxane compound that meets one or more of the following criteria—content of polar functional groups, number-average molecular weight, and amount added—to use in combination with the positive electrode active material can further improve the cycle performance of the battery without affecting the energy density and kinetic performance.

[0420] As can be seen from Examples 1 and 28-32, with the increase of the amount of organopolysiloxane compound added, the powder resistance of the positive electrode active material composition first decreases and then increases. The possible reason is that when the amount of organopolysiloxane compound added is within a certain range, its hydrophobicity can reduce the interaction between conductive agents and alleviate the aggregation of conductive agents, thereby forming a better conductive network.

[0421] 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 material composition comprising a positive electrode active material and an organopolysiloxane compound, wherein, The positive electrode active material has the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n 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.

2. The cathode material composition according to claim 1, wherein, The positive electrode active material has the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n In this context, 'a' is selected from the range of 0.97 to 1.01, 'x' is selected from the range of 0.001 to 0.005, and 'y' is selected from the range of 0.25 to 0.

5.

3. The cathode material composition according to claim 1, wherein, The organopolysiloxane compound comprises at least one structural unit represented by Formula 1. R1 and R2 independently represent H or at least one of the following functional groups: -COOH, -OH, -SH, -CN, -SCN, amino, phosphate ester, carboxylic acid ester, amide, aldehyde, sulfonyl, polyether segment, C1-C20 aliphatic hydrocarbon, C1-C20 halogenated aliphatic hydrocarbon, C1-C20 heteroaliphatic hydrocarbon, C1-C20 halogenated heteroaliphatic hydrocarbon, C6-C20 aromatic hydrocarbon, C6-C20 halogenated aromatic hydrocarbon, C2-C20 heteroaromatic hydrocarbon, C2-C20 halogenated heteroaromatic hydrocarbon.

4. The cathode material composition according to claim 1, wherein, R1 and R2 each independently represent H or at least one of the following functional groups: -COOH, -OH, -SH, amino, phosphate ester, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, phenyl.

5. The cathode material composition according to claim 1, wherein, R1 and R2 each independently represent H or at least one of the following functional groups: -OH, -SH, amino, phosphate ester, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl.

6. The cathode material composition according to any one of claims 1 to 5, wherein, The organopolysiloxane compound includes one or more selected from linear polysiloxanes and cyclic polysiloxanes.

7. The cathode material composition according to any one of claims 1 to 5, wherein, The organopolysiloxane compound is selected from linear polysiloxanes.

8. The cathode material composition according to claim 6, wherein, The linear polysiloxane also contains end-capping groups.

9. The cathode material composition according to claim 8, wherein, The end-capping group comprises at least one of the following functional groups: polyether, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, C6-C20 aromatic hydrocarbon, C1-C8 alkoxy, C2-C8 epoxy, hydroxyl, C1-C8 hydroxyalkyl, amino, C1-C8 aminoalkyl, carboxyl, and C1-C8 carboxylalkyl.

10. The cathode material composition according to claim 6, wherein, The linear polysiloxanes include one or more of the following: polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrosiloxane, carboxyl-functionalized polysiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, mercaptopropylpolysiloxane, aminoethylaminopropylpolydimethylsiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, epoxy-terminated polysiloxane, hydroxyl-terminated polydimethylsiloxane, terminal polyether polydimethylsiloxane, side-chain aminopropylpolysiloxane, side-chain hydroxymethylpolysiloxane, side-chain hydroxypropylpolysiloxane, side-chain polyether-grafted polydimethylsiloxane, and side-chain phosphate-grafted polydimethylsiloxane; and / or... The cyclic polysiloxanes include one or more of cyclic polydimethylsiloxane, cyclic polymethylvinylsiloxane, cyclic polymethylhydrosiloxane, and cyclic polymethyltrifluoropropylsiloxane.

11. The cathode material composition according to claim 6, wherein, The linear polysiloxane includes one or more of polydimethylsiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, mercaptopropyl polysiloxane, aminoethylaminopropyl polydimethylsiloxane, hydroxyl-terminated polydimethylsiloxane, terminal polyether polydimethylsiloxane, and side-chain phosphate-grafted polydimethylsiloxane; and / or The cyclic polysiloxanes include one or more of the following: 1,3,5,7-octamethylcyclotetrasiloxane, 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, cyclopentadimethylsiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, hexadecylcyclooctasiloxane, and tetradecylcycloheptasiloxane.

12. The cathode material composition according to any one of claims 1 to 5, wherein, The number average molecular weight of the organopolysiloxane compound is below 300,000.

13. The cathode material composition according to any one of claims 1 to 5, wherein, The number average molecular weight of the organopolysiloxane compound is between 400 and 80,000.

14. The cathode material composition according to any one of claims 1 to 5, wherein, The mass percentage of polar functional groups in the organopolysiloxane compound is α, where 0 ≤ α < 50%.

15. The cathode material composition according to any one of claims 1 to 5, wherein, The mass percentage of polar functional groups in the organopolysiloxane compound is α, where 5% ≤ α ≤ 30%.

16. The cathode material composition according to any one of claims 1 to 5, wherein, The content of the organopolysiloxane compound is from 0.01% to 2% by weight, based on the total weight of the cathode material composition.

17. The cathode material composition according to any one of claims 1 to 5, wherein, The content of the organopolysiloxane compound is from 0.1% to 2% by weight, based on the total weight of the cathode material composition.

18. The cathode material composition according to any one of claims 1 to 5, wherein, The surface of the positive electrode active material is also coated with carbon.

19. The cathode material composition according to any one of claims 1 to 5, wherein, A, C, and D are each independently any element within their respective ranges, and B is at least two elements within its range.

20. The cathode material composition according to any one of claims 1 to 5, wherein, 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.

21. The cathode material composition according to any one of claims 1 to 5, wherein, The B is Fe and one or more elements selected from Ti, V, Co and Mg.

22. The cathode material composition according to any one of claims 1 to 5, wherein, 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; and / or, (1-y): y is in the range of 1 to 4, and a:x is in the range of 9 to 1100.

23. The cathode material composition according to any one of claims 1 to 5, wherein, (1-y): y is in the range of 1.5 to 3, and a:x is in the range of 9 to 1100; and / or, (1-y):y is in the range of 1 to 4, and a:x is in the range of 190-998.

24. The cathode material composition according to any one of claims 1 to 5, wherein, The positive electrode active material satisfies at least one of the following conditions (1) to (4): (1) The lattice change rate of the positive electrode active material is less than 8%; (2) The concentration of Li / Mn antisite defects in the positive electrode active material is less than 2%; (3) The surface oxygen valence state of the positive electrode active material is below -1.82; (4) The compaction density of the positive electrode active material at 3T is 2.0 g / cm³. 3 above.

25. The cathode material composition according to any one of claims 1 to 5, wherein, The positive electrode active material satisfies at least one of the following conditions (1) to (4): (1) The lattice change rate of the positive electrode active material is less than 4%; (2) The concentration of Li / Mn antisite defects in the positive electrode active material is below 0.5%; (3) The surface oxygen valence state of the positive electrode active material is -1.89 to -1.98; (4) The compaction density of the positive electrode active material at 3T is 2.2 g / cm³. 3 above.

26. The cathode material composition according to any one of claims 1 to 5, wherein, It also contains conductive agents and binders.

27. The cathode material composition according to claim 26, wherein, The binder content is from 1.79% to 10% by weight, based on the total weight of the cathode material composition.

28. The cathode material composition according to claim 26, wherein, The conductive agent content is from 0.2% to 10% by weight, based on the total weight of the positive electrode material composition.

29. The cathode material composition according to any one of claims 1 to 5, wherein, The positive electrode material composition has a powder resistivity of 4 Ω / cm to 50 Ω / cm at 12 MPa; and / or, The specific surface area of ​​the cathode material composition is 8m². 2 / g to 20m 2 / g.

30. The cathode material composition according to any one of claims 1 to 5, wherein, The positive electrode material composition has a powder resistivity of 4 Ω / cm to 40 Ω / cm at 12 MPa; and / or, The specific surface area of ​​the cathode material composition is 8m². 2 / g to 15m 2 / g.

31. A method for preparing a cathode material composition, comprising the following steps: (1) Dissolve and stir the manganese source, element B source and 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) Add lithium source, phosphorus source, element A source, element C source and element D source, solvent and manganese salt doped with element B obtained in step (1) into a reaction vessel, grind and mix to obtain a slurry. (3) Transfer the slurry obtained in step (2) to a spray drying equipment for spray drying and granulation to obtain particles. (4) Sinter the particles obtained in step (3) to obtain a positive electrode active material. (5) Mix the positive electrode active material obtained in step (4) with an organopolysiloxane compound to obtain a positive electrode material composition. The positive electrode active material has the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n 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.

32. The method according to claim 31, wherein, 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 200-800 rpm; and / or, The grinding and mixing in step (2) shall be carried out for 8-15 hours; and / or, The sintering in step (4) is carried out at a temperature range of 600-900℃ for 6-14 hours.

33. The method according to claim 31 or 32, wherein, Step (2) also includes adding a carbon source to the reaction vessel and grinding and mixing it together.

34. The method according to claim 31 or 32, wherein, In step (5), the positive electrode active material, binder and conductive agent obtained in step (4) are mixed uniformly with an organopolysiloxane compound to obtain a positive electrode material composition.

35. 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 material composition according to any one of claims 1 to 30 or a positive electrode material composition prepared by any one of claims 31 to 34, and the positive electrode material composition having a content of 50% by weight or more in the positive electrode film layer based on the total weight of the positive electrode film layer.

36. The positive electrode sheet according to claim 35, wherein, The content of the positive electrode material composition in the positive electrode film is 90% to 100% by weight, based on the total weight of the positive electrode film.

37. The positive electrode sheet according to claim 35 or 36, wherein, The solid-liquid contact angle between the positive electrode film and the non-aqueous organic solvent is between 3° and 90°; and / or, The porosity of the positive electrode film is 15% to 50%.

38. The positive electrode sheet according to claim 35 or 36, wherein, The solid-liquid contact angle between the positive electrode film and the non-aqueous organic solvent is between 3° and 60°; and / or, The porosity of the positive electrode film is 20% to 40%.

39. The positive electrode sheet according to claim 35 or 36, wherein, The solid-liquid contact angle between the positive electrode film and the non-aqueous organic solvent is between 10° and 30°.

40. A secondary battery comprising a positive electrode material composition according to any one of claims 1 to 30, or a positive electrode material composition prepared by any one of claims 31 to 34, or a positive electrode sheet according to any one of claims 35 to 39.

41. An electrical device comprising the secondary battery of claim 40.

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