Positive electrode material composition, method for preparing the same, positive electrode sheet containing the same, secondary battery, and power consumption device.

Abstract

The present application provides a positive electrode material composition, a method for preparing the same, and a positive electrode sheet, a secondary battery, and a power consuming device containing the same. The positive electrode material composition has the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n and an organopolysiloxane compound. The positive electrode material composition of the present application can provide a secondary battery with a high energy density, and can simultaneously improve the rate performance, cycle performance, and / or high temperature stability of the secondary battery.

Description

[Technical Field]

[0001] This application relates to the field of battery technology, and more specifically to a positive electrode material composition, a method for preparing the same, a positive electrode sheet containing the same, a secondary battery, and a power consumption device. [Background technology]

[0002] In recent years, secondary batteries have been widely applied in many fields, including energy storage power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. With the application and widespread use of secondary batteries, their safety performance is attracting increasing attention. Lithium manganese phosphate is currently one of the most noteworthy cathode active materials due to its advantages such as high capacity, excellent safety performance, and abundant raw material sources. However, lithium manganese phosphate is prone to manganese ion leaching during charging, causing a rapid decrease in capacity. [Overview of the project]

[0003] The object of this application is to provide a positive electrode material composition, a method for preparing the same, a positive electrode sheet containing the same, a secondary battery, and a power consumption device that enable a secondary battery to have a high energy density while simultaneously improving the rate performance, cycle performance, and / or high-temperature stability of the secondary battery.

[0004] A first aspect of the present application is 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 nIt has, wherein A contains one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W, B contains one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, C contains one or more elements selected from B (boron), S, Si and N, D contains one or more elements selected from S, F, Cl and Br, a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1, and the positive electrode active material provides a positive electrode material composition that is electrically neutral.

[0005] In the present application, by simultaneously doping specific elements in specific amounts into the Li site, Mn site, P site and O site of the compound LiMnPO4, it is possible to obtain good rate performance while reducing the elution of Mn and the doping elements in the Mn site, improve the cycle performance and / or high-temperature stability, and improve the capacity per gram and tap density of the positive electrode active material. When the positive electrode active material of the present application is used in combination with an organopolysiloxane compound, the erosion of the electrolyte on the surface of the positive electrode active material can be further alleviated, and the elution of Mn and the doping elements in the Mn site can be reduced, which is advantageous for improving the electrochemical performance of the positive electrode active material. Therefore, a power consumption device including a positive electrode sheet and a secondary battery using the positive electrode material composition of the present application can have a high energy density and achieve both improved rate performance, cycle performance and / or high-temperature stability.

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

Chemical formula

[0007] In any embodiment of the present application, the organopolysiloxane compound comprises one or more selected from linear polysiloxanes and cyclic polysiloxanes, wherein the organopolysiloxane compound is selectively selected from linear polysiloxanes.

[0008] This further mitigates the erosion of acidic substances in the electrolyte from the surface of the positive electrode active material, reduces the leaching of Mn and doped elements at the Mn site, and significantly improves the battery's cycle performance and storage performance. Because cyclic polysiloxanes have a certain degree of delocalization of electrons in the ring, their Si-O skeleton has a lower affinity for electron-rich F-containing ions compared to linear polysiloxanes. Furthermore, the removal rate of F-containing ions in the electrolyte is somewhat lower, resulting in a slightly weaker effect in reducing the leaching of Mn and doped elements at the Mn site, and thus a slightly inferior improvement in battery cycle performance.

[0009] In any embodiment of the present application, the linear polysiloxane further comprises a block group. Selectively, the block group comprises at least one selected from the group consisting of functional groups such as polyethers, C1-C8 alkyl groups, C1-C8 halogenated alkyl groups, C1-C8 heteroalkyl groups, C1-C8 halogenated heteroalkyl groups, C2-C8 alkenyl groups, C2-C8 halogenated alkenyl groups, C6-C20 aromatic hydrocarbon groups, C1-C8 alkoxy groups, C2-C8 epoxy groups, hydroxyl groups, C1-C8 hydroxyalkyl groups, amino groups, C1-C8 aminoalkyl groups, carboxyl groups, and C1-C8 carboxyalkyl groups.

[0010] In any embodiment of the present application, the linear polysiloxane is polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrogensiloxane, carboxyl-functionalized polysiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, mercaptopropylpolysiloxane, aminoethylaminopropylpolydimethylsiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, terminal epoxypolysiloxane, terminal hydroxypolydimethylsiloxane, terminal The polysiloxane comprises one or more of the following: polyether polydimethylsiloxane, side-chain aminopropyl polysiloxane, side-chain hydroxylmethyl polysiloxane, side-chain hydroxylpropyl polysiloxane, side-chain polyether grafted polydimethylsiloxane, and side-chain phosphate ester grafted polydimethylsiloxane. Selectively, the linear polysiloxane comprises one or more of the following: polydimethylsiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, mercaptopropyl polysiloxane, aminoethylaminopropyl polydimethylsiloxane, terminal hydroxypolydimethylsiloxane, terminal polyether polydimethylsiloxane, and side-chain phosphate ester grafted polydimethylsiloxane.

[0011] In any embodiment of the present application, the cyclic polysiloxane comprises one or more of the following: cyclic polydimethylsiloxane, cyclic polymethylvinylsiloxane, cyclic polymethylhydrogensiloxane, and cyclic polymethyltrifluoropropylsiloxane. Selectively, 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, cyclopentapolydimethylsiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, hexadecamethylcyclooctasiloxane, and tetradecamethylcycloheptasiloxane.

[0012] In any embodiment of the present application, the number-average molecular weight of the organopolysiloxane compound is 300,000 or less, and selectively between 400 and 80,000. This makes it possible to achieve both good kinetic performance and high-temperature stability in the battery.

[0013] In any embodiment of the present application, the mass percentage of polar functional groups in the organopolysiloxane compound is α, where 0 ≤ α < 50%, and selectively 5% ≤ α ≤ 30%. This allows for better improvement of the battery's cycle performance and / or high-temperature stability.

[0014] In any embodiment of the present application, the content of the organopolysiloxane compound is 0.01% to 2% by weight, and selectively 0.1% to 2% by weight, based on the total weight of the cathode material composition. This can better improve the battery's cycle performance and / or high-temperature stability.

[0015] In any embodiment of the present application, the surface of the positive electrode active material is further coated with carbon. This improves the conductivity of the positive electrode active material.

[0016] In any embodiment of the present application, A, C, and D are each independently any element within their respective ranges, and B is at least two elements within that range. Selectively, A is an element selected from Mg and Nb. Selectively, B is at least two elements selected from Fe, Ti, V, Co, and Mg, and further, Fe and one or more elements selected from Ti, V, Co, and Mg. Selectively, C is S. Selectively, D is F. This allows for further improvements in the battery's rate performance, energy density, and / or high-temperature stability.

[0017] In any embodiment of the present application, a is selected from the range of 0.97 to 1.01.

[0018] In any embodiment of the present application, x is selected from the range of 0.001 to 0.005. This can further improve the dynamic performance of the positive electrode active material.

[0019] In any embodiment of the present application, y is selected from the range of 0.25 to 0.5. This allows for further improvement of the capacity and rate performance per gram of the positive electrode active material.

[0020] In any embodiment of the present application, z is selected from the range of 0.001 to 0.005. This can further improve the rate performance of the battery.

[0021] In any embodiment of the present application, n is selected from the range of 0.001 to 0.005. This can further improve the high-temperature stability of the battery.

[0022] In any embodiment of the present application, (1 - y):y is within the range of 1 to 4, optionally within the range of 1.5 to 3, and a:x is within the range of 9 to 1100, optionally within the range of 190 to 998. Thereby, the energy density and cycle performance of the battery can be further improved.

[0023] In any embodiment of the present application, the lattice change rate of the positive electrode active material is 8% or less, optionally 4% or less. Thereby, the rate performance of the battery can be improved.

[0024] In any embodiment of the present application, the Li / Mn anti-structure defect concentration of the positive electrode active material is 2% or less, optionally 0.5% or less. Thereby, the capacity per gram and rate performance of the positive electrode active material can be improved.

[0025] In any embodiment of the present application, the surface oxygen valence number of the positive electrode active material is -1.82 or less, optionally -1.89 to -1.98. Thereby, the cycle performance and high-temperature stability of the battery can be improved.

[0026] In any embodiment of the present application, the tap density of the positive electrode active material at 3T is 2.0 g / cm 3 or more, optionally 2.2 g / cm 3 or more. Thereby, the volume energy density of the battery can be increased.

[0027] In any embodiment of the present application, the positive electrode material composition further includes a conductive agent and a binder. Optionally, the content of the binder is 1.79 wt% to 10 wt% based on the total weight of the positive electrode material composition. Optionally, the content of the conductive agent is 0.2 wt% to 10 wt% based on the total weight of the positive electrode material composition.

[0028] In any embodiment of the present application, the powder resistivity of the positive electrode material composition at 12 MPa is 4 Ω / cm to 50 Ω / cm, and selectively 4 Ω / cm to 40 Ω / cm. This allows the battery to have better dynamic performance.

[0029] In any embodiment of the present application, the specific surface area of ​​the positive electrode material composition is 8 m². 2 / g~20m 2 / g, selectively, 8m 2 / g~15m 2 This is / g. This allows the battery to have better electrochemical performance.

[0030] A second aspect of the present application includes the steps of (1) dissolving a manganese source, a source of element B, and an acid in a solvent and stirring to produce a suspension of element B-doped manganese salt, filtering the suspension to dry the cake and obtain an element B-doped manganese salt; (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 element B-doped manganese salt obtained in step (1) to a reaction vessel and grinding and mixing to obtain a slurry; (3) transferring the slurry obtained in step (2) to a spray drying facility and spray drying and granulating to obtain particles; (4) sintering the particles obtained in step (3) to obtain a positive electrode active material; and (5) mixing the positive electrode active material obtained in step (4) with an organopolysiloxane compound, a selectable binder, and a selectable conductive agent to obtain a homogeneous 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 present invention provides a method for preparing a positive electrode material composition having the following characteristics: A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C comprises one or more elements selected from B (boron), S, Si, and N; D comprises one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1; x is selected from the range of 0.001 to 0.1; y is selected from the range of 0.001 to 0.5; z is selected from the range of 0.001 to 0.1; n is selected from the range of 0.001 to 0.1; and the positive electrode active material is electrically neutral.

[0031] In any embodiment of the present application, the stirring in step (1) is carried out at a temperature in the range of 60 to 120°C.

[0032] In any embodiment of the present application, the stirring in step (1) is performed at a stirring speed of 200 to 800 rpm.

[0033] In any embodiment of the present application, the polishing and mixing in step (2) is carried out for 8 to 15 hours.

[0034] This allows for a uniform distribution of doped elements by controlling the reaction temperature, stirring speed, and mixing time during doping. Furthermore, it increases the crystallinity of the material after sintering, thereby improving the capacity and rate performance per gram of the positive electrode active material.

[0035] In any embodiment of the present invention, the sintering in step (4) is carried out at a temperature range of 600 to 900°C for 6 to 14 hours. This improves the high-temperature stability and cycle performance of the battery.

[0036] In any embodiment of the present application, step (2) further includes adding a carbon source to the reaction vessel and polishing and mixing. This makes it possible to obtain a positive electrode active material coated with carbon on its surface.

[0037] A third aspect of the present application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode material composition according to the first aspect of the present application or a positive electrode material composition prepared by the method according to the second aspect of the present 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.

[0038] In any embodiment of the present 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.

[0039] In any embodiment of the present application, the solid-liquid contact angle between the positive electrode film layer and the non-aqueous organic solvent is between 3° and 90°, selectively between 3° and 60°, and further between 10° and 30°. When the contact angle is within an appropriate range, the battery can achieve both high energy density and good rate performance, cycle performance, and high-temperature stability.

[0040] In any embodiment of the present application, the porosity of the positive electrode film layer is 15% to 50%, and selectively 20% to 40%. When the porosity is within an appropriate range, the battery can achieve both high energy density and good rate performance, cycle performance, and high-temperature stability.

[0041] A fourth aspect of the present application provides a secondary battery comprising a positive electrode material composition according to the first aspect of the present application, a positive electrode material composition prepared by the method according to the second aspect of the present application, or a positive electrode sheet according to the third aspect of the present application.

[0042] A fifth aspect of the present application provides a power consumption device including a secondary battery according to the fourth aspect of the present application.

[0043] The positive electrode sheet, secondary battery, and power consumption device of the present invention include the positive electrode material composition of the present invention and therefore have at least the same advantages as the said positive electrode material composition. [Brief explanation of the drawing]

[0044] To more clearly explain the technical concept of the embodiments of this application, the drawings required in the embodiments of this application are briefly described below. As is clear, the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without expending any creative effort. [Figure 1] This is a schematic diagram of one embodiment of the secondary battery of the present invention. [Figure 2] Figure 1 is an exploded schematic diagram of an embodiment of a secondary battery. [Figure 3] This is a schematic diagram of one embodiment of the battery module of the present invention. [Figure 4] This is a schematic diagram of one embodiment of the battery pack of the present invention. [Figure 5] Figure 4 is an exploded schematic diagram of an embodiment of the battery pack shown. [Figure 6] This is a schematic diagram of one embodiment of a power consumption device that includes the secondary battery of the present invention as a power source. [Figure 7] The X-ray diffraction (XRD) patterns of undoped LiMnPO4 and the positive electrode active material prepared in Example 2 are shown. [Figure 8] The X-ray energy dispersion (EDS) spectrum of the positive electrode active material prepared in Example 2 is shown. In the figure, the proportions are not necessarily drawn to the actual values. [Modes for carrying out the invention]

[0045] The following describes in detail, with reference to the drawings as appropriate, embodiments of the positive electrode material composition, method for preparing the same, and positive electrode sheets, secondary batteries, and power consumption devices specifically disclosed in this application. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter described in the claims.

[0046] The “range” disclosed in this application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting one lower limit and one upper limit, the selected lower limit and upper limit limit the boundary of a special range. The range thus limited may be an endpoint or a range that does not include endpoints, or may be any combination, that is, any lower limit may be combined with any upper limit. For example, if the ranges 60-120 and 80-110 are given for a particular parameter, the ranges 60-110 and 80-120 can also be expected. Also, if the minimum range values ​​1 and 2 and the maximum range values ​​3, 4 and 5 are given, the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 can all be expected. In this application, unless otherwise stated, the numerical range “a-b” is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" in this specification indicates that all real numbers between "0 to 5" are listed, and "0 to 5" is an abbreviation for combinations of these numbers. Also, when a parameter is described 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.

[0047] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and such technical solutions should be considered to be included in the disclosures of this application.

[0048] Unless otherwise specified, all technical features and selectable technical features of this application can be combined to form new technical solutions, and such technical solutions should be considered to be included in the disclosures of this application.

[0049] Unless otherwise specified, all steps of this invention may be performed sequentially, randomly, and preferably sequentially. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, when the method may further include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or further include steps (c), (a), and (b), and so on.

[0050] Unless otherwise specified, the terms “equipped with” and “included” as used in this application may be open or closed. For example, the terms “equipped with” and “included” may include or include other components not further listed, or may include or include only the listed components.

[0051] 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, any of the following conditions satisfy the “A or B” condition: 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).

[0052] Here, substituents of compounds are disclosed in groups or ranges. Such descriptions are clearly expected to also include individual subcombinations of members of these groups and ranges. For example, the term "C1-C8 alkyl group" is clearly expected to disclose 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 individually.

[0053] In this specification, the term "aliphatic hydrocarbon group" includes alkyl groups, alkenyl groups, and alkynyl groups, and the term "heteroaliphatic hydrocarbon group" means an aliphatic hydrocarbon group containing a heteroatom (e.g., N, O, S). The term "heteroalkyl group" means an alkyl group containing a heteroatom (e.g., N, O, S), which may be an alkoxy group, an alkylthio group, etc.

[0054] In this specification, the terms "multiple" and "multiple types" refer to two or more types.

[0055] In this specification, "approximately" XX (a certain number) represents a range, specifically a range of 90% to 110% of that number.

[0056] The inventors of this invention discovered, in actual work, that lithium manganese phosphate (LiMnPO4), the positive electrode active material, exhibits relatively serious manganese ion leaching during the deep charge-discharge process. While prior art attempts to reduce interfacial side reactions by coating lithium manganese phosphate with lithium iron phosphate, such coatings cannot prevent the leached manganese ions from migrating into the electrolyte. The leached manganese ions then migrate to the negative electrode and are reduced to metallic manganese. These generated metallic manganese act as a "catalyst," catalyzing the decomposition of the SEI film (solid electrolyte interphase) on the negative electrode surface. Some of the generated byproducts are gases, easily causing battery swelling and affecting the battery's safety performance. Other byproducts accumulate on the negative electrode surface, obstructing the passage of lithium ions to and from the negative electrode, increasing battery resistance, and affecting the battery's dynamic performance. Furthermore, the constant consumption of active lithium ions in the electrolyte and within the battery to compensate for the lost SEI film irreversibly impacts the battery's capacity retention rate.

[0057] The inventors of this application repeatedly investigated the effects of doping the Li, Mn, P, and O sites of lithium manganese phosphate with various elements. As a result, they found that an improved lithium manganese phosphate cathode active material can be obtained by simultaneously doping specific elements in specific amounts at the four aforementioned sites. At the same time, the inventors discovered that using the improved lithium manganese phosphate cathode active material in combination with an organopolysiloxane compound is advantageous in fully exhibiting the electrochemical performance of the improved lithium manganese phosphate cathode active material because it can mitigate electrolyte erosion on the surface of the improved lithium manganese phosphate cathode active material. Cathode material composition

[0058] Specifically, a first aspect of the present application provides a positive electrode material composition comprising a positive electrode active material and an organopolysiloxane compound.

[0059] The positive electrode active material is of the chemical formula Li aA x Mn 1-y B y P 1-z C z O 4-n D n The positive electrode active material is electrically neutral, wherein A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C comprises one or more elements selected from B (boron), S, Si, and N; D comprises one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1; x is selected from the range of 0.001 to 0.1; y is selected from the range of 0.001 to 0.5; z is selected from the range of 0.001 to 0.1; n is selected from the range of 0.001 to 0.1.

[0060] Unless otherwise specified, in the above chemical formula, if A is two or more elements, the limitation of the numerical range of x above refers not only to the limitation of the stoichiometric number for each element that constitutes A, but also to the limitation of the sum of the stoichiometric numbers of each element that constitutes A. For example, if A is two or more elements A1, A2, ..., An, then the stoichiometric numbers x1, x2, ..., xn of A1, A2, ..., An must each be within the numerical range limited by this application with respect to x, and the sum of x1, x2, ..., xn must also be within this numerical range. Similarly, if B, C, and D are two or more elements, the limitation of the numerical range of the stoichiometric numbers of B, C, and D in this application has the same meaning as above.

[0061] 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 into the Li site, Mn site, P site, and O site of the compound LiMnPO4, respectively. Although not limited to theory, it is thought to be involved in improving the performance of lithium manganese phosphate and reducing the lattice change rate and surface activity of lithium manganese phosphate during the lithium desorption / insertion process. By reducing the lattice change rate, the difference in lattice constants between the two phases at the grain boundary is reduced, thereby reducing interfacial stress, and Li + This enhances the transport capacity at the interface and improves the rate performance of the positive electrode active material. Due to high surface activity, interfacial side reactions are serious, promoting gas generation, electrolyte consumption, and interface breakdown, affecting battery cycle performance and other aspects. In this application, the rate of lattice change is reduced by doping Li and Mn sites. Doping of Mn sites effectively reduces surface activity and can suppress manganese ion elution and interfacial side reactions between the positive electrode active material and the electrolyte. Doping of P sites increases the rate of change of Mn-O bond length, lowers the small polaron transition barrier of the material, and is advantageous for improving electronic conductivity. Doping of O sites has a good effect in reducing interfacial side reactions. Doping of P and O sites also affects manganese ion elution and kinetic performance of antistructural defects.

[0062] Therefore, doping can reduce the concentration of anti-structural defects in the positive electrode active material, improve the kinetic performance and volume per gram of the positive electrode active material, and further alter the particle morphology and improve the pressure density. The inventors of this application have unexpectedly discovered that by simultaneously doping specific elements in specific amounts to the Li, Mn, P, and O sites of the compound LiMnPO4, improved rate performance can be obtained, as well as reducing the elution of doping elements from Mn and the Mn site, improving cycle performance and / or high-temperature stability, and also improving the volume per gram and pressure density of the positive electrode active material. Selectively, 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.

[0063] The positive electrode material composition of the present invention comprises a positive electrode active material and an organopolysiloxane compound. The inventors of the present invention have discovered that using the above positive electrode active material and organopolysiloxane compound in combination is advantageous in mitigating electrolyte erosion from the surface of the positive electrode active material, reducing the elution of Mn and Mn-site doping elements, and improving the electrochemical performance of the positive electrode active material. This is because the Si-O skeleton of the organopolysiloxane compound can reduce the acidity of the electrolyte by removing F-containing ions in the electrolyte, thereby mitigating the erosion of acidic substances in the electrolyte from the surface of the positive electrode active material. Furthermore, the organopolysiloxane compound has a certain degree of water repellency, and after preparing a positive electrode sheet together with the positive electrode active material, the contact angle between the obtained positive electrode sheet and the electrolyte increases, thereby mitigating electrolyte erosion from the surface of the positive electrode active material.

[0064] Therefore, a positive electrode sheet and a power consumption device such as a secondary battery using the positive electrode material composition of the present invention can have a high energy density while simultaneously achieving improved rate performance, cycle performance, and / or high-temperature stability.

[0065] Furthermore, by comparing the XRD spectra before and after doping with LiMnPO4 in this application, we discovered that the positions of the main characteristic peaks of the positive electrode active material and LiMnPO4 before doping are almost identical. This indicates that the doped lithium manganese phosphate positive electrode active material of this application does not have an impurity phase, and that the improvement in battery performance is mainly due to elemental doping, not an impurity phase.

[0066] In some embodiments, A, C, and D are each independently any element within their respective ranges, and B is at least two elements within that range. This allows for easier and more precise control of the composition of the positive electrode active material.

[0067] Selectively, A is an element selected from Mg and Nb.

[0068] Selectively, B is at least two elements selected from Fe, Ti, V, Co, and Mg, and selectively, Fe and one or more elements selected from Ti, V, Co, and Mg.

[0069] Selectively, C is S.

[0070] Selectively, D is F.

[0071] By selecting doping elements for the Li site within the above range, the lattice change rate during lithium desorption can be further reduced, thereby improving the battery's rate performance. By selecting doping elements for the Mn site within the above range, the electronic conductivity can be further improved, the lattice change rate can be further reduced, and the battery's rate performance and energy density can be improved. By selecting doping elements for the P site within the above range, the battery's rate performance can be further improved. By selecting doping elements for the O position within the above range, interfacial side reactions can be further reduced, improving the battery's high-temperature stability.

[0072] The value of 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 of a is selected from the range of 0.97 to 1.01.

[0073] The aforementioned x is selected from the range of 0.001 to 0.1, for example, 0.001 or 0.005.

[0074] The aforementioned 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, and 0.4.

[0075] The aforementioned z is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, and 0.1.

[0076] The aforementioned n is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, and 0.1.

[0077] In some embodiments, x is selected from the range of 0.001 to 0.005.

[0078] In some embodiments, y is selected from the range of 0.01 to 0.5, and selectively selected from the range of 0.25 to 0.5.

[0079] In some embodiments, z is selected from the range of 0.001 to 0.005.

[0080] In some embodiments, n is selected from the range of 0.001 to 0.005.

[0081] By selecting the value of x within the above range, the dynamic performance of the positive electrode active material can be further improved. By selecting the value of y within the above range, the capacity per gram and rate performance of the positive electrode active material can be further improved. By selecting the value of z within the above range, the rate performance of the battery can be further improved. By selecting the value of n within the above range, the high-temperature stability of the battery can be further improved.

[0082] In some embodiments, the positive electrode active material satisfies the following conditions: (1-y):y is in the range of 1 to 4, selectively in the range of 1.5 to 3, and a:x is in the range of 9 to 1100, selectively in the range of 190 to 998. Here, y represents the sum of the stoichiometric numbers of the doped elements at the Mn site. By satisfying the above conditions, the energy density and cycle performance of the battery can be further improved.

[0083] 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.

[0084] In some embodiments, the lattice change rate of the positive electrode active material is 8% or less, and selectively, 4% or less. Reducing the lattice change rate makes the transport of Li ions easier, i.e., the ability of Li ions to transfer to the material is strengthened, which is advantageous for improving the rate performance of the battery. The lattice change rate can be measured by methods well known in the art, such as X-ray diffraction (XRD).

[0085] In some embodiments, the Li / Mn antistructure defect concentration of the positive electrode active material is 2% or less, and selectively, the Li / Mn antistructure defect concentration is 0.5% or less. A Li / Mn antistructure defect is a defect in which Li in a LiMnPO4 lattice... + and Mn 2+ This refers to the reversal of positions. Li / Mn antistructure defect concentration refers to the position of Mn in the positive electrode active material. 2+ Li was replaced by + Li + This is a percentage of the total amount. Mn of anti-structural defects 2+ Li + Inhibiting the transport of Li / Mn and reducing the antistructure defect concentration of Li / Mn is advantageous in improving the capacity and rate performance per gram of the cathode active material. The antistructure defect concentration of Li / Mn can be measured by methods well known in this field, such as XRD.

[0086] In some embodiments, the surface oxygen valency of the positive electrode active material is -1.82 or less, and selectively between -1.89 and -1.98. By reducing the surface oxygen valency, interfacial side reactions between the positive electrode active material and the electrolyte can be reduced, thereby improving the battery's cycle performance and high-temperature stability. The surface oxygen valency can be measured by methods well known in the art, such as electron energy loss spectroscopy (EELS).

[0087] In some embodiments, the pressure density of the positive electrode active material at 3T (tons) is 2.0 g / cm³. 3 The above is the result, and selectively 2.2 g / cm³ 3 That concludes the explanation. As the pressure density increases, the weight of the positive electrode active material per unit volume increases, so improving the pressure density is advantageous for improving the volumetric energy density of the battery. The pressure density can be measured in accordance with GB / T24533-2009.

[0088] In some embodiments, the organopolysiloxane compound comprises at least one structural unit represented by Formula 1. [ka] R1 and R2 each independently represent at least one selected from the group consisting of functional groups such as -COOH, -OH, -SH, -CN, -SCN, amino group, phosphate ester group, carboxylic acid ester group, amide group, aldehyde group, sulfonyl group, polyether segment, C1-C20 aliphatic hydrocarbon group, C1-C20 halogenated aliphatic hydrocarbon group, C1-C20 heteroaliphatic hydrocarbon group, C1-C20 halogenated heteroaliphatic hydrocarbon group, C6-C20 aromatic hydrocarbon group, C6-C20 halogenated aromatic hydrocarbon group, C2-C20 heteroaromatic hydrocarbon group, or C2-C20 halogenated halogenated heteroaromatic hydrocarbon group, or H. Selectively, R1 and R2 each independently represent at least one selected from the group consisting of functional groups such as -COOH, -OH, -SH, amino group, phosphate ester group, polyether segment, C1-C8 alkyl group, C1-C8 halogenated alkyl group, C1-C8 heteroalkyl group, C1-C8 halogenated heteroalkyl group, C2-C8 alkenyl group, C2-C8 halogenated alkenyl group, and phenyl group, or H. More selectively, R1 and R2 each independently represent at least one selected from the group consisting of functional groups such as -OH, -SH, amino group, phosphate ester group, polyether segment, C1-C8 alkyl group, C1-C8 halogenated alkyl group, C1-C8 heteroalkyl group, C1-C8 halogenated heteroalkyl group, C2-C8 alkenyl group, and C2-C8 halogenated alkenyl group, or H.

[0089] These functional groups play a role in complexing manganese ions and / or reacting with acidic substances in the electrolyte, reducing the leaching of Mn and doped elements at the Mn sites, and further improving the battery's cycle performance and / or high-temperature stability.

[0090] If these functional groups also possess electron-withdrawing properties, it is possible to further electronically deficiency Si in the Si-O framework of the organopolysiloxane compound, thereby further improving affinity with F-containing ions in the electrolyte, further mitigating erosion of acidic substances in the electrolyte from the surface of the positive electrode active material, reducing the elution of Mn and doped elements at the Mn site, and significantly improving the battery's cycle performance and / or high-temperature stability.

[0091] In some embodiments, the organopolysiloxane compound comprises one or more selected from linear polysiloxanes and cyclic polysiloxanes, and selectively, the organopolysiloxane compound is selected from linear polysiloxanes.

[0092] This further mitigates the erosion of acidic substances in the electrolyte from the surface of the positive electrode active material, reduces the leaching of Mn and doped elements at the Mn site, and significantly improves the battery's cycle performance and storage performance. Because cyclic polysiloxanes have a certain degree of delocalization of electrons in the ring, their Si-O skeleton has a lower affinity for electron-rich F-containing ions compared to linear polysiloxanes. Furthermore, the removal rate of F-containing ions in the electrolyte is somewhat lower, resulting in a slightly weaker effect in reducing the leaching of Mn and doped elements at the Mn site, and thus a slightly inferior effect in improving battery cycle performance.

[0093] In some embodiments, the linear polysiloxane may further contain a block group. Selectively, the block group includes at least one selected from the group consisting of functional groups such as polyethers, C1-C8 alkyl groups, C1-C8 halogenated alkyl groups, C1-C8 heteroalkyl groups, C1-C8 halogenated heteroalkyl groups, C2-C8 alkenyl groups, C2-C8 halogenated alkenyl groups, C6-C20 aromatic hydrocarbon groups, C1-C8 alkoxy groups, C2-C8 epoxy groups, hydroxyl groups, C1-C8 hydroxyalkyl groups, amino groups, C1-C8 aminoalkyl groups, carboxyl groups, and C1-C8 carboxyalkyl groups.

[0094] In some embodiments, the molecular formula of the cyclic polysiloxane is shown in formula 2, where m represents the degree of polymerization of the structural unit shown in formula 1. Selectively, m ≤ 12, m ≤ 11, m ≤ 10, m ≤ 9, or m ≤ 8. [ka]

[0095] As an example, the linear polysiloxanes mentioned above include polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrogensiloxane, carboxyl-functionalized polysiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, mercaptopropylpolysiloxane, aminoethylaminopropylpolydimethylsiloxane, and methoxy-terminated polydimethylsiloxane. This includes, but is not limited to, one or more of the following: lusiloxane, hydroxypropyl-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, terminal epoxypolysiloxane, terminal hydroxypolydimethylsiloxane, terminal polyetherpolydimethylsiloxane, side-chain aminopropylpolysiloxane, side-chain hydroxylmethylpolysiloxane, side-chain hydroxylpropylpolysiloxane, side-chain polyether-grafted polydimethylsiloxane, and side-chain phosphate-grafted polydimethylsiloxane.

[0096] Selectively, the linear polysiloxane comprises one or more of the following: polydimethylsiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, mercaptopropylpolysiloxane, aminoethylaminopropylpolydimethylsiloxane, terminal hydroxypolydimethylsiloxane, terminal polyether polydimethylsiloxane, and side-chain phosphate ester graft polydimethylsiloxane.

[0097] As an example, the cyclic polysiloxane includes, but is not limited to, one or more of the following: cyclic polydimethylsiloxane, cyclic polymethylvinylsiloxane, cyclic polymethylhydrogensiloxane, and cyclic polymethyltrifluoropropylsiloxane.

[0098] Selectively, the cyclic polysiloxane includes one or more of the following: 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, hexadecamethylcyclooctasiloxane, and tetradecamethylcycloheptasiloxane.

[0099] In some embodiments, the number-average molecular weight of the organopolysiloxane compound is 300,000 or less, and may be, for example, 400-300,000, 400-200,000, 400-100,000, 400-80,000, 400-50,000, 400-20,000, 400-10,000, 1,000-100,000, 1,000-50,000, 1,000-20,000, or 1,000-10,000. The number-average molecular weight of the organopolysiloxane compound can be measured by methods well known in the art, such as gel permeation chromatography (GPC). A PL-GPC 220 high-temperature gel permeation chromatograph can be used as the measuring instrument. In this application, the "organopolysiloxane compound" may be an oligomer or a high polymer.

[0100] When the number-average molecular weight of the organopolysiloxane compound is within an appropriate range, the battery can achieve both good kinetic performance and high-temperature stability. Furthermore, the following situations can be effectively avoided: If the number-average molecular weight of the organopolysiloxane compound is too small, its poor hydrophobicity prevents it from effectively increasing the contact angle between the positive electrode film layer and the electrolyte, thus failing to effectively mitigate electrolyte erosion on the positive electrode active material surface, and potentially preventing improvements in the battery's cycle performance and / or high-temperature stability. If the number-average molecular weight of the organopolysiloxane compound is too large, its hydrophobicity increases, which is also unfavorable for slurry dispersion and may affect the improvement in battery performance.

[0101] In some embodiments, the mass percentage of polar functional groups in the organopolysiloxane compound is α, where 0 ≤ α < 50%. Selectively, 5% ≤ α ≤ 30%.

[0102] In this application, "mass percentage of polar functional groups in organopolysiloxane compounds" means the mass ratio of polar functional groups in R1, R2 and block groups 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 and -NH-), phosphate ester groups, carboxylate groups (-COO-), amide groups (-CONH-), aldehyde groups (-CHO), sulfonyl groups (-S(=O)2-), polyether segments, halogen atoms, alkoxy groups, and epoxy groups. When the polar functional groups are directly bonded to silicon atoms, α represents the mass fraction of these polar functional groups in the organopolysiloxane compound. When the polar functional groups are not directly bonded 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 bonded to them in the organopolysiloxane compound, where "divalent to tetravalent methyl groups" refers to carbon atoms directly bonded to the polar functional groups and located between the polar functional groups and silicon atoms, as well as other nonpolar functional groups bonded to carbon atoms. For example, in polymethyltrifluoropropylsiloxane, α represents the mass percentage of -CF3, excluding the ethylene group. For example, in polymethylchloropropylsiloxane, α represents the mass percentage of -CH2Cl, excluding the ethylene group. For example, in hydroxypropyl-terminated polydimethylsiloxane, α represents the mass percentage of -CH2OH. The mass percentage of polar functional groups in organopolysiloxane compounds can be measured by methods known in this field, such as titration (e.g., acid-alkali titration, redox titration, precipitation titration), infrared spectroscopy, and nuclear magnetic resonance spectroscopy.

[0103] When the content of polar functional groups in the organopolysiloxane compound is within an appropriate range, the acidity of the electrolyte is reduced and the effect of removing fluorine-containing ions in the electrolyte is better. This better mitigates the erosion of acidic substances in the electrolyte from the surface of the positive electrode active material, and the battery's cycle performance and / or high-temperature stability can be better improved. Furthermore, the following situation can be effectively avoided: If the content of polar functional groups in the organopolysiloxane compound is too high, the effect of reducing the acidity of the electrolyte and removing fluorine-containing ions in the electrolyte will not be further improved, and the contact angle between the positive electrode film layer and the electrolyte may become small, which may prevent the improvement in the battery's cycle performance and / or high-temperature stability from being achieved.

[0104] In some embodiments, the content of the organopolysiloxane compound is 0.01% to 2% by weight, and selectively 0.1% to 2% by weight, based on the total weight of the positive electrode material composition. When the content of the organopolysiloxane compound is within an appropriate range, the effect of reducing the acidity of the electrolyte and removing F-containing ions in the electrolyte is better, thereby better mitigating the erosion of acidic substances in the electrolyte from the positive electrode active material surface and better improving the battery's cycle performance and / or high-temperature stability. Furthermore, the following situations can be effectively avoided: If the content of the organopolysiloxane compound is too high, it may affect the wettability of the electrolyte in the positive electrode film layer and thus affect the battery's dynamic performance. Also, because the organopolysiloxane compound does not provide capacity, if the content is too high, it may reduce the battery's energy density. If the organopolysiloxane compound content is too low, its effect of reducing the acidity of the electrolyte and removing F-containing ions from the electrolyte is not clear, and it may not be able to effectively mitigate the erosion of acidic substances in the electrolyte from the surface of the positive electrode active material, thus failing to improve the battery's cycle performance and / or high-temperature stability.

[0105] In some embodiments, the cathode material composition may further contain a binder. The binder may be a substance that exhibits an adhesive effect well known in the art, and selectively, the binder includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins. Selectively, the binder content is 1.79% to 10% by weight, and selectively 2% to 5% by weight, based on the total weight of the cathode material composition.

[0106] In some embodiments, the cathode material composition may further contain a conductive agent. The conductive agent may be a substance that exhibits an electron conduction effect well known in the art, and selectively, the cathode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjenblack, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Selectively, the content of the conductive agent is 0.2% to 10% by weight, and selectively 0.5% to 5% by weight, based on the total weight of the cathode material composition.

[0107] In some embodiments, the powder resistivity of the positive electrode material composition at 12 MPa is 4 Ω / cm to 50 Ω / cm, and selectively 4 Ω / cm to 40 Ω / cm. By adjusting the powder resistivity of the positive electrode material composition to an appropriate range, the battery can have better dynamic performance. The powder resistivity of the positive electrode material composition can be measured by methods well known in the art. For example, it can be tested using a powder resistivity tester, referring to GB / T 30835-2014. One exemplary test method includes the steps of weighing a certain amount of sample powder to be measured, placing it in a special mold, and setting the test pressure to obtain the powder resistivity under different pressures. In this application, the test pressure can be set to 12 MPa. The measuring instrument may be a Suzhou Crystal ST2722-SZ type four-probe powder resistivity meter.

[0108] In some embodiments, the specific surface area of ​​the positive electrode material composition is 8 m². 2 / g~20m 2 / g, selectively, 8m 2 / g~15m 2 The value is / g. By adjusting the specific surface area of ​​the positive electrode material composition to an appropriate range, interfacial side reactions between the positive electrode sheet and the electrolyte can be reduced, thereby reducing the volume expansion of the battery and improving the electrochemical performance of the battery. The specific surface area of ​​the positive electrode material composition can be measured by methods well known in this field. For example, it can be tested by employing the nitrogen adsorption specific surface area analysis test method, referring to GB / T 19587-2017, and calculated by the BET (Brunauer Emmett Teller) method. The nitrogen adsorption specific surface area analysis test can be performed using the Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, Inc., USA. Preparation method

[0109] A second aspect of the present application relates to a method for preparing a positive electrode material composition of the first aspect of the present application, comprising: (1) dissolving a manganese source, a source of element B, and an acid in a solvent and stirring to produce a suspension of element B-doped manganese salt, filtering the suspension to dry the cake and obtain an element B-doped manganese salt; (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 element B-doped manganese salt obtained in step (1) to a reaction vessel and grinding and mixing to obtain a slurry; (3) transferring the slurry obtained in step (2) to a spray drying facility and spray drying and granulating to obtain particles; (4) sintering the particles obtained in step (3) to obtain a positive electrode active material; and (5) mixing the positive electrode active material obtained in step (4) with an organopolysiloxane compound, a selectable binder, and a selectable conductive agent to obtain a homogeneous positive electrode material composition.

[0110] In some embodiments, the source of element A is at least one selected from element A, oxides, phosphates, oxalates, carbonates, and sulfates; the source of element B is at least one selected from element B, oxides, phosphates, oxalates, carbonates, and sulfates; the source of element C is at least one selected from element C sulfates, borates, nitrates, and silicates; and the source of element D is at least one selected from element D and ammonium salts. By selecting the source for each doped element, the uniformity of the doped element distribution can be improved, thereby improving the performance of the positive electrode active material.

[0111] In some embodiments, the acid is one or more types selected from hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and organic acids such as oxalic acid, for example. In some embodiments, the acid is a dilute acid with a concentration of 60% by weight or less.

[0112] In some embodiments, the manganese source may be a manganese-containing substance used in the preparation of lithium manganese phosphate, which is well known in the art. For example, the manganese source may be one or a combination selected from elemental manganese, manganese dioxide, manganese phosphate, manganese oxalate, and manganese carbonate.

[0113] In some embodiments, the lithium source may be a lithium-containing substance used in the preparation of lithium manganese phosphate, which is well known in the art. For example, the lithium source may be one or a combination selected from lithium carbonate, lithium hydroxide, lithium phosphate, and lithium dihydrogen phosphate.

[0114] In some embodiments, the phosphorus source may be a phosphorus-containing substance used in the preparation of lithium manganese phosphate, which is well known in the art. For example, the phosphorus source may be one or a combination thereof selected from diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, and phosphoric acid.

[0115] The amount of each source of elements A, B, C, and D added depends on the target doping level, and the ratio of the amounts used from lithium, manganese, and phosphorus sources conforms to the stoichiometric ratio.

[0116] In some embodiments, the solvent in step (1) and step (2) may be any solvent that is commonly used by those skilled in the art in the preparation of manganese salts and lithium manganese phosphate, for example, at least one selected from ethanol and water (e.g., deionized water).

[0117] In some embodiments, the stirring in step (1) is carried out at a temperature in the range of 60 to 120°C. In some embodiments, the stirring in step (1) is carried out at a stirring speed of 200 to 800 rpm, or 300 to 800 rpm, or 400 to 800 rpm. In some embodiments, the stirring in step (1) is carried out for 6 to 12 hours. In some embodiments, the polishing and mixing in step (2) is carried out for 8 to 15 hours.

[0118] By controlling the reaction temperature, stirring speed, and mixing time during doping, the doped elements can be uniformly distributed, and the crystallinity of the material after sintering can be increased, thereby improving the capacity per gram and rate performance of the positive electrode active material.

[0119] In some embodiments, the cake may be washed before drying in step (1).

[0120] In some embodiments, the drying in step (1) can be carried out by methods and conditions known to those skilled in the art. For example, the drying temperature may be in the range of 120 to 300°C. Selectively, after drying, the cake is polished into particles, for example, the median diameter Dv of the particles. 50 Polish until the median diameter Dv is within the range of 50-200 nm. 50 This refers to the particle size corresponding to the point when the cumulative volume distribution percentage of the material reaches 50%. In this application, the median diameter Dv of the material is 50 This can be measured by laser diffraction particle size analysis. For example, it can be measured using a laser particle size analyzer (e.g., Malvern Master Size 3000) referring to standard GB / T 19077-2016.

[0121] In some embodiments, in step (2), a carbon source is further added to the reaction vessel for polishing and mixing. This allows the method to obtain a positive electrode active material coated with carbon on its surface. Selectively, the carbon source includes one or more of the following: starch, sucrose, glucose, polyvinyl alcohol, polyethylene glycol, and citric acid. The amount of the carbon source used is typically in the range of 0.1% to 5% in molar ratio relative to the amount of the lithium source used. The polishing can be carried out by a suitable polishing method known in the art, for example, by a sand mill.

[0122] In some embodiments, the temperature and time of spray drying in step (3) may be the normal temperature and time for spray drying in the art, for example, 100 to 300°C for 1 to 6 hours.

[0123] In some embodiments, in step (4), sintering is carried out at a temperature range of 600-900°C for 6-14 hours. By controlling the sintering temperature and time, the degree of crystallinity of the positive electrode active material can be controlled, and the amount of Mn and doped elements leached from the Mn sites after cycling can be reduced, thereby improving the high-temperature stability and cycle performance of the battery.

[0124] In some embodiments, the sintering in step (4) is carried out under a protective atmosphere which is nitrogen gas, an inert gas, hydrogen gas, or a mixture thereof. Positive electrode sheet

[0125] A third aspect of the present application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode material composition according to the first aspect of the present application or a positive electrode material composition prepared by the method of the second aspect of the present 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.

[0126] The positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0127] In some embodiments, the content of the positive electrode material composition in the positive electrode film layer is selectively 90% to 100% by weight based on the total weight of the positive electrode film layer.

[0128] The positive electrode film layer does not exclude any 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 further contain other positive electrode active materials other than the positive electrode active material of this application, and selectively, the other positive electrode active material may contain at least one of lithium transition metal oxides and their modified compounds. As an example, the other positive electrode active material may contain 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 modified compounds thereof.

[0129] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. As an example, the metal material is at least one selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer material substrate is selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0130] In some embodiments, the solid-liquid contact angle between the positive electrode film layer and the non-aqueous organic solvent is between 3° and 90°, selectively between 3° and 60°, and further between 10° and 30°. When the contact angle is within an appropriate range, the battery can achieve both high energy density and good rate performance, cycle performance, and high-temperature stability. Furthermore, the following situations can be effectively avoided: If the contact angle is too small, the erosion of acidic substances in the electrolyte from the positive electrode active material surface cannot be effectively mitigated, and the effect on improving cycle performance is not clear. If the contact angle is too large, the wettability of the electrolyte to the positive electrode film layer deteriorates, which may affect the battery's rate performance and cycle performance. The solid-liquid contact angle between the positive electrode film layer and the non-aqueous organic solvent is well known in the art and can be tested by methods known in the art, for example, by referring to GBT 30693-2014. One exemplary measurement method includes the step of dropping a droplet of non-aqueous organic solvent onto the surface of the positive electrode sheet at room temperature and measuring the contact angle for 60 seconds using a contact angle meter. The test equipment can be the LSA 200 optical contact angle meter from LAUDA Scientific GmbH in Germany. As the non-aqueous organic solvent, any non-aqueous organic solvent known in this field for use in the non-aqueous electrolyte of secondary batteries can be used, and selectively, ethylene carbonate (EC) can be used as the non-aqueous organic solvent.

[0131] In some embodiments, the porosity of the positive electrode film layer is 15% to 50%, and selectively 20% to 40%. When the porosity is within an appropriate range, the battery can achieve both high energy density and good rate performance, cycle performance, and high-temperature stability. Furthermore, the following situations can be effectively avoided: If the porosity is too small, the wettability of the electrolyte in the positive electrode film layer will be poor, which may affect the rate performance and cycle performance of the battery. If the porosity is too large, it may affect the overall energy density of the battery. The porosity of the positive electrode film layer has a meaning known in the art and can be measured by methods known in the art. For example, it can be measured by peeling off the positive electrode film layer with adhesive tape and referring to GB / T 24586-2009. The porosity P = [(V2-V1) / V2] × 100%. V1(cm 3 V2(cm²) represents the true volume and can be measured by combining Archimedes' principle and Bohr's law using the substitution method with an inert gas having a small molecular diameter (e.g., helium gas). 3 ) represents the apparent volume, V² = S × H × A, S (cm 2 ) represents area, H(cm) represents thickness, and A represents the number of samples.

[0132] The positive electrode film layer is typically formed by applying a positive electrode slurry to a positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing a positive electrode active material, a selectable conductive agent, a selectable binder, and any other components in a solvent and stirring them uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP).

[0133] Note that the parameters of each positive electrode film layer related to this application (e.g., contact angle, porosity, etc.) all refer to the parameters of the positive electrode film layer on one side of the positive electrode current collector. If positive electrode film layers are provided on both sides of the positive electrode current collector, it is considered that the system is within the scope of protection of this application if the parameters of either one of the positive electrode film layers satisfy the requirements of this application.

[0134] Furthermore, the parameter tests for the positive electrode film layer described above may be performed by sampling during the preparation process of the positive electrode sheet or battery, or by sampling from the prepared battery. When the test sample is sampled from a prepared battery, for example, sampling can be performed according to the following steps: The battery is discharged (generally, the battery is fully discharged for safety). After removing the battery, the positive electrode sheet is removed, and the positive electrode sheet is immersed in dimethyl carbonate (DMC) for a certain period of time (e.g., 2 to 10 hours). The positive electrode sheet is then removed and dried at a certain temperature and time (e.g., 60°C for 4 hours). After drying, the positive electrode sheet is removed, and at this time, the parameters related to the positive electrode film layer described above can be sampled and tested from the dried positive electrode sheet. secondary battery

[0135] A fourth aspect of the present application provides a secondary battery including the positive electrode sheet of the third aspect of the present application.

[0136] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be used continuously after discharge by recharging to activate the active material. Typically, secondary batteries consist of an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is placed between the positive and negative electrode sheets and primarily serves to prevent short circuits between the positive and negative electrodes, while simultaneously allowing active ions to pass through. The electrolyte plays a role in transporting active ions between the positive and negative electrode sheets. [Positive electrode sheet]

[0137] The positive electrode sheet used in the secondary battery of the present application is the positive electrode sheet described in any embodiment of the third aspect of the present application. [Negative electrode sheet]

[0138] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector and containing a negative electrode active material. For example, the negative electrode current collector has two opposing surfaces in the thickness direction, and the negative electrode film layer is provided on the two opposing surfaces of the negative electrode current collector.

[0139] As the negative electrode active material, negative electrode active materials for secondary batteries known in the art can be used. For 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 material. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material. This application is not limited to these materials, and other conventionally known materials used as negative electrode active materials for secondary batteries may be used. These negative electrode active materials may be used individually or in combination of two or more.

[0140] In some embodiments, the negative electrode film layer may optionally further contain a negative electrode conductive agent. The type of the negative electrode conductive agent is not particularly limited in this application. For 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.

[0141] In some embodiments, the negative electrode film layer may optionally further contain a negative electrode binder. In this application, the type of negative electrode binder is not particularly limited. For example, the negative electrode binder may contain at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylate PAA, polymethacrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0142] In some embodiments, the negative electrode film layer may selectively further contain other additives. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC) or PTC thermistor material.

[0143] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. Copper foil can be used as an example of a metal foil. A composite current collector may include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. For example, the metal material may be at least one selected from copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer material substrate can be selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and the like.

[0144] The negative electrode film layer is typically formed by applying a negative electrode slurry to a negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing a negative electrode active material, a selectable conductive agent, a selectable binder, and other selectable auxiliary agents in a solvent and stirring them uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0145] The negative electrode sheet does not exclude any additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet according to the present application further includes a conductive primer layer (e.g., consisting of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and provided on the surface of the negative electrode current collector. In some other embodiments, the negative electrode sheet described in the present application further includes a protective layer covering the surface of the negative electrode film layer. [Electrolyte]

[0146] In this application, the type of electrolyte is not particularly limited and can be selected as required. For example, the electrolyte may be at least one selected from solid electrolytes and liquid electrolytes (electrolytes).

[0147] In some embodiments, the electrolyte is an electrolyte solution, which comprises an electrolyte salt and a solvent.

[0148] The type of electrolyte salt is not particularly limited and can be selected according to actual requirements. In some embodiments, the electrolyte salt may include, for example, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium disoxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodisoxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0149] The type of solvent is not particularly limited and can be selected according to the actual requirements. In some embodiments, the solvent may, for example, include at least one of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0150] In some embodiments, the electrolyte may further selectively contain additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve some aspects of the battery's performance, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature power performance. [Separator]

[0151] In secondary batteries using an electrolyte or a solid electrolyte, a separator is also included. The separator is provided between the positive electrode sheet and the negative electrode sheet and mainly serves to prevent short circuits between the positive and negative electrodes, while simultaneously allowing active ions to pass through. In this application, the type of separator is not particularly limited, and any known porous structure separation membrane having good chemical and mechanical stability can be selected.

[0152] In some embodiments, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film. If the separator is a multilayer composite film, the materials of each layer may be the same or different.

[0153] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet can be assembled into an electrode assembly by a winding process and / or a lamination process.

[0154] In some embodiments, the secondary battery may include an enclosure, which is used to seal the electrode assembly and electrolyte described above.

[0155] In some embodiments, the casing of the secondary battery may be a hard case, such as a rigid plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a soft bag, such as a bag soft bag. The material of the soft package may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), or polybutylene succinate (PBS).

[0156] In this application, the shape of the secondary battery is not particularly limited and may be cylindrical, rectangular, or any other shape. Figure 1 shows a rectangular secondary battery 5 as an example.

[0157] In some embodiments, as shown in Figure 2, the exterior may include a case 51 and a cover plate 53. The case 51 includes a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates enclose each other to form a housing chamber. The case 51 has an opening that communicates with the housing chamber, and the cover plate 53 covers the opening to seal the housing chamber. The positive electrode sheet, negative electrode sheet and separator can be formed into an electrode assembly 52 by a winding process and / or a lamination process. The electrode assembly 52 is packaged into the housing chamber. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more and may be adjusted as required.

[0158] The method for manufacturing the secondary battery of the present invention is known. In some embodiments, a secondary battery can be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. For example, an electrode assembly can be formed by winding or laminating the positive electrode sheet, separator, and negative electrode sheet, the electrode assembly can be placed in an outer casing, dried, and then the electrolyte can be injected. A secondary battery can then be obtained through processes such as vacuum sealing, standing, chemical formation, and shaping.

[0159] In some embodiments of the present invention, the secondary battery according to the present invention may be assembled into a battery module, and the number of secondary batteries included in the battery module may be multiple, and the specific number may be adjusted according to the application and capacity of the battery module.

[0160] Figure 3 is a schematic diagram of an example battery module 4. As shown in Figure 3, in the battery module 4, the multiple secondary batteries 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary batteries 5 may be fixed together with fasteners.

[0161] Selectively, the battery module 4 further includes a housing having a housing space, and a plurality of secondary batteries 5 are housed in the housing space.

[0162] In some embodiments, the battery modules may be assembled into a battery pack. The number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0163] Figures 4 and 5 are schematic diagrams of an example battery pack 1. As shown in Figures 4 and 5, the battery pack 1 may include a battery housing and a plurality of battery modules 4 provided in the battery housing. The battery housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 3 to form a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery housing in any manner. power consumption equipment

[0164] A fifth aspect of the present application provides a power consumption device comprising at least one of the secondary battery, battery module, or battery pack of the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage means for the power consumption device. The power consumption 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.), trains, ships, and satellites, energy storage systems, etc.

[0165] The aforementioned power consumption device can select a secondary battery, battery module, or battery pack depending on the demand.

[0166] Figure 6 is a schematic diagram of an example of a power consumption device. This power consumption device includes pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, etc. To meet the high power and high energy density requirements of this power consumption device, battery packs or battery modules can be used.

[0167] Other examples of power-consuming devices may include mobile phones, tablet computers, and laptop computers. These power-consuming devices are typically required to be thin, and rechargeable batteries can be used as their power source. Examples

[0168] The following examples illustrate the contents of this application in more detail; however, these examples are merely illustrative, and it will be apparent to those skilled in the art that various modifications and changes can be made within the scope of the disclosure. All parts, percentages, and ratios described in the following examples are based on mass unless otherwise specified. Furthermore, all reagents used in the examples may be commercially available or synthesized according to conventional methods, and may be used as is without requiring further processing. Furthermore, all apparatus used in the examples are commercially available. Example 1

[0169] 1) Preparation of positive electrode active material Preparation of doped manganese oxalate: 1.3 mol MnSO4·H2O and 0.7 mol 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 in terms of oxalic acid) were added. The reaction vessel was heated to 80°C and stirred at a rotation speed of 600 rpm for 6 hours until the reaction was complete (no bubbles were formed), yielding a Fe-doped manganese oxalate suspension. The suspension was then filtered, the cake was dried at 120°C, and then polished to obtain a median diameter Dv 50 This yielded manganese oxalate particles doped with Fe at a wavelength of approximately 100 nm.

[0170] Preparation of doped lithium manganese phosphate: 1 mol of the above manganese oxalate particles, 0.497 mol of lithium carbonate, 0.001 mol of Mo(SO4)3, an 85% aqueous phosphoric acid 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 polished and stirred for 10 hours to obtain a slurry. The slurry was transferred to a spray drying facility and spray-dried and granulated, with the drying temperature set to 250°C and dried for 4 hours to obtain particles. The above powder was sintered at 700°C for 10 hours in a protective atmosphere of nitrogen gas (90 vol%) + hydrogen gas (10 vol%) 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 yielded the positive electrode active material. The elemental content can be detected by inductively coupled plasma atomic emission spectroscopy (ICP).

[0171] 2) Preparation of coin cells A positive electrode material composition was obtained by stirring in a stirrer in a weight ratio of 89.4:5:5:0.6 between a positive electrode active material, a conductive agent (acetylene black), a binder (polyvinylidene fluoride (PVDF)), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is approximately 12%, number average molecular weight is 3700). After stirring until the materials were uniformly mixed, the positive electrode material composition was added to N-methylpyrrolidone (NMP) and stirred in a drying chamber to obtain a slurry. The slurry was applied to aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet. The application amount was 0.015 g / cm². 2 The pressure density is 2.0 g / cm³. 3 That is the case.

[0172] A lithium sheet was used as the negative electrode, and a 1 mol / L solution of LiPF6 in ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1 was used as the electrolyte. The coin cell was assembled in a coin cell box together with the positive electrode sheet prepared above. 3) Preparation of full cells

[0173] A positive electrode material composition was obtained by stirring in a stirrer in a weight ratio of 93.4:1.5:4.5:0.6. The positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is approximately 12%, number average molecular weight is 3700) until the materials were uniformly mixed. After that, the 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 / cm². 2 The pressure density is 2.4 g / cm³. 3 That is the case.

[0174] The negative electrode active materials, artificial graphite and hard carbon, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethylcellulose (CMC), were uniformly mixed in deionized water in a weight ratio of 90:5:2:2:1. This mixture was then applied to copper foil, dried, and cold-pressed to obtain a negative electrode sheet. The coating amount was 0.0075 g / cm². 2 The pressure density is 1.7 g / cm³. 3 That is the case.

[0175] A porous polyethylene (PE) polymerized film was used as a separator, and a positive electrode sheet, separator, and negative electrode sheet were laminated in order, with the separator positioned between the positive and negative electrodes to act as a separator. The assembly was then wound up to obtain an electrode assembly. The electrode assembly was placed in an outer casing, and the same electrolyte used in the preparation described above was injected and sealed to obtain a full cell. Examples 2-27

[0176] Aside from 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. Example 2

[0177] 1) Preparation of positive electrode active material: The amount of Li2CO3 was changed to 0.4885 mol, Mo(SO4)3 was changed to MgSO4, the amount of FeSO4·H2O was changed to 0.68 mol, an additional 0.02 mol of Ti(SO4)2 was added during the preparation of doped manganese oxalate, and H4SiO4 was changed to HNO3. All other conditions were the same as in Example 1. Example 3

[0178] 1) Preparation of positive electrode active material: Except for changing the amount of Li2CO3 to 0.496 mol, changing Mo(SO4)3 to W(SO4)3, and changing H4SiO4 to H2SO4, all other conditions were the same as in Example 1. Example 4

[0179] 1) Preparation of positive electrode active material: Except for changing the amount of Li2CO3 to 0.4985 mol, changing 0.001 mol of Mo(SO4)3 to 0.0005 mol of Al2(SO4)3, and changing NH4HF2 to NH4HCl2, all other conditions were the same as in Example 1. Example 5

[0180] 1) Preparation of positive electrode active material: The amount of FeSO4·H2O was changed to 0.69 mol, an additional 0.01 mol of VCl2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4965 mol, 0.001 mol of Mo(SO4)3 was changed to 0.0005 mol of Nb2(SO4)5, and H4SiO4 was changed to H2SO4. All other conditions were the same as in Example 1. Example 6

[0181] 1) Preparation of positive electrode active material: The amount of FeSO4·H2O was changed to 0.68 mol, an additional 0.01 mol of VCl2 and 0.01 mol of MgSO4 were added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4965 mol, 0.001 mol of Mo(SO4)3 was changed to 0.0005 mol of Nb2(SO4)5, and H4SiO4 was changed to H2SO4. All other conditions were the same as in Example 1. Example 7

[0182] 1) Preparation of positive electrode active material: Except for changing MgSO4 to CoSO4, all other conditions were the same as in Example 6. Example 8

[0183] 1) Preparation of positive electrode active material: Except for changing MgSO4 to NiSO4, all other conditions were the same as in Example 6. Example 9

[0184] 1) Preparation of positive electrode active material: The amount of FeSO4·H2O was changed to 0.698 mol, an additional 0.002 mol of Ti(SO4)2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4955 mol, 0.001 mol of Mo(SO4)3 was changed to 0.0005 mol of Nb2(SO4)5, H4SiO4 was changed to H2SO4, and NH4HF2 was changed to NH4HCl2. All other conditions were the same as in Example 1. Example 10

[0185] 1) Preparation of positive electrode active material: The amount of FeSO4·H2O was changed to 0.68 mol, an additional 0.01 mol of VCl2 and 0.01 mol of MgSO4 were added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4975 mol, 0.001 mol of Mo(SO4)3 was changed to 0.0005 mol of Nb2(SO4)5, and NH4HF2 was changed to NH4HBr2. All other conditions were the same as in Example 1. Example 11

[0186] 1) Preparation of positive electrode active material: The amount of FeSO4·H2O was changed to 0.69 mol, an additional 0.01 mol of VCl2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.499 mol, Mo(SO4)3 was changed to MgSO4, and NH4HF2 was changed to NH4HBr2. All other conditions were the same as in Example 1. Example 12

[0187] 1) Preparation of positive electrode active material: The amount of MnSO4·H2O was changed to 1.36 mol, the amount of FeSO4·H2O was changed to 0.6 mol, an additional 0.04 mol of VCl2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4985 mol, Mo(SO4)3 was changed to MgSO4, and H4SiO4 was changed to HNO3. All other conditions were the same as in Example 1. Example 13

[0188] 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, all other conditions were the same as in Example 12. Example 14

[0189] 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, all other conditions were the same as in Example 12. Example 15

[0190] 1) Preparation of positive electrode active material: The amount of MnSO4·H2O was changed to 1.2 mol, an additional 0.1 mol of VCl2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.494 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, and H4SiO4 was changed to H2SO4. All other conditions were the same as in Example 1. Example 16

[0191] 1) Preparation of positive electrode active material: The amount of MnSO4·H2O was changed to 1.2 mol, an additional 0.1 mol of VCl2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.467 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, 0.001 mol of H4SiO4 was changed to 0.005 mol of H2SO4, and 1.175 mol of 85% phosphoric acid was changed to 1.171 mol of 85% phosphoric acid. All other conditions were the same as in Example 1. Example 17

[0192] 1) Preparation of positive electrode active material: The amount of MnSO4·H2O was changed to 1.2 mol, an additional 0.1 mol of VCl2 was added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.492 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, H4SiO4 was changed to H2SO4, and the amount of NH4HF2 was changed to 0.0025 mol. All other conditions were the same as in Example 1. Example 18

[0193] 1) Preparation of positive electrode active material: The amount of FeSO4·H2O was changed to 0.5 mol, an additional 0.1 mol of VCl2 and 0.1 mol of CoSO4 were added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.492 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, H4SiO4 was changed to H2SO4, and the amount of NH4HF2 was changed to 0.0025 mol. All other conditions were the same as in Example 1. Example 19

[0194] 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, all other conditions were the same as in Example 18. Example 20

[0195] 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, all other conditions were the same as in Example 18. Example 21

[0196] 1) Preparation of positive electrode active material: Except for changing 0.1 mol of CoSO4 to 0.1 mol of NiSO4, all other conditions were the same as in Example 18. Example 22

[0197] 1) Preparation of positive electrode active material: The other conditions were the same as in Example 18, except that the amount of MnSO4·H2O was changed to 1.5 mol, the amount of FeSO4·H2O was changed to 0.2 mol, and 0.1 mol of CoSO4 was changed to 0.2 mol of NiSO4. Example 23

[0198] 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, all other conditions were the same as in Example 18. Example 24

[0199] 1) Preparation of positive electrode active material: The amount of MnSO4·H2O was changed to 1.2 mol, the amount of FeSO4·H2O was changed to 0.5 mol, an additional 0.1 mol of VCl2 and 0.2 mol of CoSO4 were added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.497 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, H4SiO4 was changed to H2SO4, and the amount of NH4HF2 was changed to 0.0025 mol. All other conditions were the same as in Example 1. Example 25

[0200] 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, all other conditions were the same as in Example 18. Example 26

[0201] 1) Preparation of positive electrode active material: The amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.3 mol, an additional 0.1 mol of VCl2 and 0.2 mol of CoSO4 were added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.4825 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, the amount of H4SiO4 was changed to 0.1 mol, the amount of phosphoric acid was changed to 0.9 mol, and the amount of NH4HF2 was changed to 0.04 mol. All other conditions were the same as in Example 1. Example 27

[0202] 1) Preparation of positive electrode active material: The amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.3 mol, an additional 0.1 mol of VCl2 and 0.2 mol of CoSO4 were added during the preparation of doped manganese oxalate, the amount of Li2CO3 was changed to 0.485 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, the amount of H4SiO4 was changed to 0.08 mol, the amount of phosphoric acid was changed to 0.92 mol, and the amount of NH4HF2 was changed to 0.05 mol. All other conditions were the same as in Example 1. Examples 28-32

[0203] In "2) Preparation of coin cells" and "3) Preparation of full cells," the conditions were the same as in Example 1, except that the weight percentage of aminoethylaminopropyl polydimethylsiloxane in the cathode material composition was adjusted. Example 28

[0204] 2) Preparation of coin cells A positive electrode material composition was obtained by stirring a positive electrode active material, a conductive agent (acetylene black), a binder (polyvinylidene fluoride (PVDF)), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is approximately 12%, number average molecular weight is 3700) in a weight ratio of 89.99:5:5:0.01 in a stirrer until the materials were uniformly mixed.

[0205] 3) Preparation of full cells A positive electrode material composition was obtained by stirring a positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) in a weight ratio of 93.99:1.5:4.5:0.01 in a stirrer until the materials were uniformly mixed. Example 29

[0206] 2) Preparation of coin cells A positive electrode material composition was obtained by stirring a positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) in a weight ratio of 89.9:5:5:0.1 in a stirrer until the materials were uniformly mixed.

[0207] 3) Preparation of full cells A positive electrode material composition was obtained by stirring a positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) in a weight ratio of 93.9:1.5:4.5:0.1 in a stirrer until the materials were uniformly mixed. Example 30

[0208] 2) Preparation of coin cells A positive electrode material composition was obtained by stirring a positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) in a weight ratio of 89:5:5:1 in a stirrer until the materials were uniformly mixed.

[0209] 3) Preparation of full cells A positive electrode material composition was obtained by stirring a positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) in a weight ratio of 93:1.5:4.5:1 in a stirrer until the materials were uniformly mixed. Example 31

[0210] 2) Preparation of coin cells A positive electrode material composition was obtained by stirring a positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is about 12%, number average molecular weight is 3700) in a weight ratio of 88:5:5:2 in a stirrer until the materials were uniformly mixed.

[0211] 3) Preparation of full cells A positive electrode material composition was obtained by stirring a positive electrode active material, a conductive agent (acetylene black), a binder (polyvinylidene fluoride (PVDF)), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is approximately 12%, number average molecular weight is 3700) in a weight ratio of 92:1.5:4.5:2 in a stirrer until the materials were uniformly mixed. Example 32

[0212] 2) Preparation of coin cells A positive electrode material composition was obtained by stirring a positive electrode active material, a conductive agent (acetylene black), a binder (polyvinylidene fluoride (PVDF)), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is approximately 12%, number average molecular weight is 3700) in a weight ratio of 86:5:5:4 in a stirrer until the materials were uniformly mixed.

[0213] 3) Preparation of full cells A positive electrode material composition was obtained by stirring a positive electrode active material, a conductive agent (acetylene black), a binder (polyvinylidene fluoride (PVDF)), and aminoethylaminopropyl polydimethylsiloxane (polar functional groups -CH2NH2 and -CH2NH-, mass percentage α is approximately 12%, number average molecular weight is 3700) in a weight ratio of 90:1.5:4.5:4 until the materials were uniformly mixed in a stirrer. Examples 33-50

[0214] In "2) Preparation of coin cells" and "3) Preparation of full cells," all other conditions are the same as in Example 1, except that aminoethylaminopropyl polydimethylsiloxane in the cathode material composition is replaced with the following organopolysiloxane compounds, respectively.

[0215] Example 33: Polydimethylsiloxane (with a polar functional group mass percentage α of approximately 0% and a number-average molecular weight of 1200).

[0216] Example 34: Polymethylchloropropylsiloxane (with polar functional groups of -CH2Cl, mass percentage α of approximately 30.2%, and number average molecular weight of 2500).

[0217] Example 35: Polymethyltrifluoropropylsiloxane (with polar functional group -CF3, mass percentage α approximately 44.0%, and number average molecular weight 1400).

[0218] Example 36: Mercaptopropyl polysiloxane (with polar functional groups of -CH2SH, mass percentage α of approximately 15.0%, and number average molecular weight of 2000).

[0219] Example 37: Terminal hydroxypolydimethylsiloxane (with polar functional groups of -OH, mass percentage α of approximately 3.4%, and number average molecular weight of 1000).

[0220] Example 38: Methoxy-terminated polydimethylsiloxane (with a polar functional group being a methoxy group, a mass percentage α of approximately 3.1%, and a number-average molecular weight of 2800).

[0221] Example 39: Terminal polyether polydimethylsiloxane (the polar functional group is a polyether segment, with a mass percentage α of approximately 10.0% and a number average molecular weight of 2110).

[0222] Example 40: Side-chain phosphate ester grafted polydimethylsiloxane (the polar functional group is a phosphate ester group, with a mass percentage α of approximately 1.4% and a number-average molecular weight of 15600).

[0223] Example 41: 1,3,5,7-Octamethylcyclotetrasiloxane (with a mass percentage α of polar functional groups of approximately 0% and a molecular weight of 280).

[0224] Example 42: Cyclopentapolydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a molecular weight of 370).

[0225] Example 43: Terminal polyether polydimethylsiloxane (the polar functional group is a polyether segment, with a mass percentage α of approximately 55.0% and a number average molecular weight of 25132).

[0226] Example 44: Polydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a number-average molecular weight of 400).

[0227] Example 45: Polydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a number-average molecular weight of 10,000).

[0228] Example 46: Polydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a number-average molecular weight of 50,000).

[0229] Example 47: Polydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a number-average molecular weight of 80,000).

[0230] Example 48: Polydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a number-average molecular weight of 100,000).

[0231] Example 49: Polydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a number-average molecular weight of 300,000).

[0232] Example 50: Polydimethylsiloxane (with a mass percentage α of polar functional groups of approximately 0% and a number-average molecular weight of 400,000). Comparative Example 1

[0233] 1) Preparation of positive electrode active material Preparation of manganese oxalate: 1 mol of MnSO4·H2O was placed in a reaction vessel, and 10 L of deionized water and 1 mol of oxalic acid dihydrate (calculated in terms of oxalic acid) were added. The reaction vessel was heated to 80°C and stirred at a rotation speed of 600 rpm for 6 hours until the reaction was complete (no bubbles were formed), and a manganese oxalate suspension was obtained. The suspension was then filtered, the cake was dried at 120°C, and then polished to obtain a median diameter Dv 50 This yielded manganese oxalate particles with a size of 50-200 nm.

[0234] Preparation of lithium manganese phosphate: 1 mol of the above manganese oxalate particles, 0.5 mol of lithium carbonate, 1 mol of phosphoric acid in an 85% aqueous phosphoric acid solution, and 0.005 mol of sucrose were added to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly polished and stirred for 10 hours to obtain a slurry. The slurry was transferred to a spray drying facility and spray-dried and granulated, with the drying temperature set to 250°C and dried for 4 hours to obtain particles. The above powder material was sintered at 700°C for 10 hours in a protective atmosphere of nitrogen gas (90 vol%) + hydrogen gas (10 vol%) to obtain carbon-coated LiMnPO4.

[0235] 2) Preparation of coin cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1.

[0236] 3) Preparation of full cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1. Comparative Example 2

[0237] 1) Preparation of the positive electrode active material In Comparative Example 1, 1 mol of MnSO4·H2O was changed to 0.85 mol of MnSO4·H2O and 0.15 mol of FeSO4·H2O, put into a mixer and mixed well for 6 hours, and then added to a reaction kettle. Other conditions were the same as those in Comparative Example 1.

[0238] 2) Preparation of coin cells Other conditions were the same as those in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added.

[0239] 3) Preparation of full cells Other conditions were the same as those in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added. Comparative Example 3

[0240] 1) Preparation of the positive electrode active material The amount of MnSO4·H2O was changed to 1.9 mol, 0.7 mol of FeSO4·H2O was changed to 0.1 mol of ZnSO4, the amount of Li2CO3 was changed to 0.495 mol, 0.001 mol of Mo(SO4)3 was changed to 0.005 mol of MgSO4, the amount of phosphoric acid was changed to 1 mol, and other conditions were the same as those in Example 1 except that H4SiO4 and NH4HF2 were not added.

[0241] 2) Preparation of coin cells Other conditions were the same as those in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added.

[0242] 3) Preparation of full cells Other conditions were the same as those in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added. Comparative Example 4

[0243] 1) Preparation of the positive electrode active material 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, changing 0.001 mol of Mo(SO4)3 to 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, all other conditions were the same as in Example 1.

[0244] 2) Preparation of coin cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1.

[0245] 3) Preparation of full cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1. Comparative Example 5

[0246] 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 0.6 mol, the amount of Li2CO3 to 0.38 mol, and changing 0.001 mol of Mo(SO4)3 to 0.12 mol of MgSO4, all other conditions were the same as in Example 1.

[0247] 2) Preparation of coin cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1.

[0248] 3) Preparation of full cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1. Comparative Example 6

[0249] 1) Preparation of positive electrode active material The amount of MnSO4·H2O was changed to 0.8 mol, 0.7 mol of FeSO4·H2O was changed to 1.2 mol of ZnSO4, the amount of Li2CO3 was changed to 0.499 mol, and 0.001 mol of Mo(SO4)3 was changed to 0.001 mol of MgSO4. Other conditions were the same as in Example 1.

[0250] 2) Preparation of coin cell Other conditions were the same as in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added.

[0251] 3) Preparation of full cell Other conditions were the same as in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added. Comparative Example 7

[0252] 1) Preparation of cathode active material The amount of MnSO4·H2O was changed to 1.4 mol, the amount of FeSO4·H2O was changed to 0.6 mol, the amount of Li2CO3 was changed to 0.534 mol, 0.001 mol of Mo(SO4)3 was changed to 0.001 mol of MgSO4, the amount of phosphoric acid was changed to 0.88 mol, the amount of H4SiO4 was changed to 0.12 mol, and the amount of NH4HF2 was changed to 0.025 mol. Other conditions were the same as in Example 1.

[0253] 2) Preparation of coin cell Other conditions were the same as in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added.

[0254] 3) Preparation of full cell Other conditions were the same as in Example 1 except that aminoethylaminopropyl polydimethylsiloxane was not added. Comparative Example 8

[0255] 1) Preparation of cathode active material 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 0.474 mol, changing 0.001 mol of Mo(SO4)3 to 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, all other conditions are the same as in Example 1.

[0256] 2) Preparation of coin cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1.

[0257] 3) Preparation of full cells Except for the absence of aminoethylaminopropylpolydimethylsiloxane, all other conditions were the same as in Example 1. Comparative Example 9

[0258] In "2) Preparation of coin cells" and "3) Preparation of full cells," all other conditions were the same as in Example 1, except that aminoethylaminopropyl polydimethylsiloxane was not added. Test methods for positive electrode active material, positive electrode material composition, positive electrode sheet, and battery performance 1. Method for measuring the rate of change in the grid

[0259] Under constant temperature conditions of 25°C, a sample of the positive electrode active material is placed in an X-ray diffractometer (model: Bruker D8 Discover), and the sample is tested at 1° / min. The test data is then analyzed and compiled, and the lattice constants a0, b0, c0, and v0 are calculated by referring to a standard PDF card (a0, b0, and c0 represent the magnitude of the length in each direction of the unit cell, and v0 represents the volume of the unit cell, which can be obtained directly from the XRD precision correction results).

[0260] Using the coin cell preparation method described in the above embodiment, a sample of the positive electrode active material was prepared into a coin cell, and the coin cell was charged at a small rate of 0.05C until the current decreased to 0.01C. Next, the positive electrode sheet was removed from the coin cell, placed in DMC, and immersed for 8 hours. After that, it was dried, the powder was scraped off, and particles with a particle size of less than 500 nm were selected. A sample was taken and its lattice constant v1 was calculated in the same manner as the test of the fresh sample described above, and (v0-v1) / v0 × 100% is shown in the table as the lattice change rate before and after complete lithium desorption / insertion. 2. Method for measuring Li / Mn antistructure defect concentration

[0261] The XRD results measured using the "Method for Measuring Lattice Change Rate" are compared with a PDF (Powder Diffraction File) card of a standard crystal to obtain the Li / Mn antistructure defect concentration. Specifically, the XRD results measured using the "Method for Measuring Lattice Change Rate" are imported into the General Structure Analysis System (GSAS) software, and the software automatically acquires a precisely corrected result that includes the site occupation status of different atoms. The Li / Mn antistructure defect concentration is then obtained by reading this precisely corrected result. 3. Method for measuring surface oxygen valency

[0262] 5 g of positive electrode active material sample was taken, and a coin cell was prepared according to the coin cell preparation method described in the above example. The coin cell was then charged at a small rate of 0.05 C until the current decreased to 0.01 C. Next, the positive electrode sheet from the coin cell was removed, placed in DMC, and immersed for 8 hours. After drying, the powder was scraped off, and particles with a particle size of less than 500 nm were selected. The obtained particles were measured using electron energy loss spectroscopy (EELS, instrument model Talos F200S) to obtain energy loss fine structure (ELNES) that reflects the density of states and energy level distribution of the elements. From the density of states and energy level distribution, the number of occupied electrons was calculated by integrating the density of states data of the valence band, and the surface oxygen valence after charging was estimated. 4. Method for measuring pressure density

[0263] A 5g sample of positive electrode active material powder was placed in a compaction mold (CARVER mold, model 13mm, USA), and then the mold was placed in a compaction density instrument. A pressure of 3 tons was applied, and the thickness of the powder under pressure (thickness after depressurization; the area of ​​the test container was 1540.25 mm²) was measured on the instrument. 2 The data was read, and the pressure density was calculated using ρ = m / v. 5. Powder Resistivity Test

[0264] By placing an appropriate amount of cathode material composition sample powder for preparing a full cell into a dedicated mold of a powder resistivity measuring instrument and setting the test pressure, powder resistivity at different pressures can be obtained. In this application, the test pressure is 12 MPa. The test instrument is a Suzhou Crystal ST2722-SZ type four-probe powder resistivity measuring instrument. 6. Specific surface area test

[0265] 5 g of a sample powder of the cathode material composition for preparing a full cell was taken, and its specific surface area was tested using a Tri-Star 3020 specific surface area and pore size analysis machine from Micromeritics, Inc., USA. The specific surface area was calculated using the BET (Brunauer Emmett Teller) method. 7. Contact Angle Test

[0266] At room temperature, ethylene carbonate (EC) droplets were dropped onto the surface of the positive electrode film layer, and the solid-liquid contact angle was measured for 60 seconds using an LSA 200 optical contact angle meter from LAUDA Scientific GmbH in Germany. 8. Method for measuring the initial volume per gram of coin cells

[0267] Under constant temperature conditions of 25°C, the coin cell was charged to 4.3V at 0.1C, then charged at a constant voltage of 4.3V until the current was less than 0.05mA, left to stand for 5 minutes, and then discharged to 2.0V at 0.1C. The discharge capacity at this time was the initial capacity per gram and was defined as D0. 9.3C Charging Constant Current Ratio Measurement Method

[0268] Under constant temperature conditions of 25°C, a fresh full cell was left standing for 5 minutes and discharged to 2.5V at 1 / 3C. After standing for 5 minutes, it was charged to 4.3V at 1 / 3C, and then charged at a constant voltage of 4.3V until the current was less than 0.05mA. After standing for 5 minutes, the charge capacity at this time was recorded as C0. It was then discharged to 2.5V at 1 / 3C, left standing for 5 minutes, and then charged again to 4.3V at 3C, left standing for 5 minutes, and the charge capacity at this time was recorded as C1. The constant current ratio for 3C charging is C1 / C0 × 100%.

[0269] A higher constant current ratio in 3C charging indicates better battery rate performance. 10. Full cell 60°C expansion gas test

[0270] Full cells in a 100% charged state (SOC) were stored at 60°C. The open-circuit voltage (OCV) and AC internal resistance (IMP) of the cells were measured before, during, and after storage to monitor the SOC, and the volume of the cells was also measured. After every 48 hours of storage, a full cell was removed, allowed to stand for 1 hour, and then the open-circuit voltage (OCV) and internal resistance (IMP) were tested. After cooling to room temperature, the volume of the cells was measured by the drainage method. In the drainage method, the gravitational force F1 of the cells was measured individually using a balance that automatically converts units using dial data, and then the cells were completely deionized with water (density 1 g / cm³). 3 (Assume) Place the battery in this position and measure the gravitational force F2 of the battery at this time, and the buoyancy F acting on the battery 浮力 It is F1-F2, and Archimedes' principle F 浮力 =ρ × g × V 排出 Based on this, the battery volume V = (F1 - F2) / (ρ × g) is calculated.

[0271] Based on the OCV and IMP test results, the batteries in the examples consistently maintained a State of Charge (SOC) of 99% or higher until storage was completed during this test process.

[0272] After 30 days of storage, the battery volume was measured, and the percentage increase in the battery volume after storage compared to the battery volume before storage was calculated. 11. Full cell cycle performance test at 45°C

[0273] Under a constant temperature environment of 45°C, a full cell was charged to 4.3V at 1C, and then charged at a constant voltage of 4.3V until the current was less than 0.05mA. After standing for 5 minutes, it was discharged to 2.5V at 1C, and the discharge capacity at this time was recorded as E0. The above charge-discharge cycle was repeated until the discharge capacity decreased to 80% of E0. The number of battery cycles at this time was recorded. 12. Method for measuring the amount of Mn (and Fe doped at Mn sites) eluted after cycling.

[0274] A full cell, cycled at 45°C until its capacity was reduced to 80%, was discharged at a rate of 0.1C to a cutoff voltage of 2.0V. The battery was then disassembled, the negative electrode sheet was removed, and a unit area (1540.25 mm²) was applied to the negative electrode sheet. 2 Thirty wafers were randomly selected and tested using inductively coupled plasma atomic emission spectroscopy (ICP) with an Agilent ICP-OES730. From the ICP results, the amount of Fe (when Fe is doped into the Mn sites of the cathode active material) and Mn was calculated, and the amount of Mn (and Fe doped into the Mn sites) leached out after cycling was calculated. The test standard conforms to EPA-6010D-2014. 13. Measurement of the chemical formula of the positive electrode active material

[0275] Using a spherical aberration electron microscope (ACSTEM), the internal microstructure and surface structure of the cathode active material are characterized with high spatial resolution, and the chemical formula of the cathode active material is obtained using three-dimensional reconstruction techniques.

[0276] Table 1 shows the compositions of the positive electrode active materials for Examples 1-11 and Comparative Examples 1-9.

[0277] Table 2 shows the compositions of the positive electrode active materials for Examples 12 to 27.

[0278] Table 3 shows the types and content of organopolysiloxane compounds in the cathode material compositions for Examples 1 to 52.

[0279] Table 4 shows the performance data of the positive electrode active materials, positive electrode material compositions, positive electrode sheets, coin cells, or full cells of Examples 1 to 11 and Comparative Examples 1 to 9, measured according to the performance test method described above.

[0280] Table 5 shows the performance data of the positive electrode active material, positive electrode material composition, positive electrode sheet, coin cell, or full cell of Examples 12 to 27, measured according to the performance test method described above.

[0281] Table 6 shows the performance data of the cathode material compositions, cathode sheets, coin cells, or full cells of Examples 28 to 50, measured according to the performance test method described above.

[0282] [Table 1]

[0283] [Table 2]

[0284] [Table 3]

[0285] [Table 4]

[0286] [Table 5]

[0287] [Table 6]

[0288] As can be seen from Tables 4 and 5 above, each of the positive electrode active materials in the embodiments of this application achieved superior effects compared to the comparative examples in one or all of the following: cycle performance, high-temperature stability, capacity per gram, and pressure density. By simultaneously doping specific elements in specific amounts to the Li, Mn, P, and O sites of LiMnPO4, improved cycle performance can be obtained. Furthermore, while reducing the elution of Mn and Fe, it is possible to improve the improved cycle performance and / or high-temperature stability, as well as the capacity per gram and pressure density of the positive electrode active material. When the positive electrode active materials of the embodiments of this application are used in combination with organopolysiloxane compounds, the erosion of the electrolyte from the surface of the positive electrode active material can be further mitigated and the elution of Mn and Fe can be reduced, thereby further improving the cycle performance of the battery.

[0289] A comparison between Examples 18-20 and 23-25 ​​shows that, given the same other elements, if (1-y):y is within the range of 1 to 4, the energy density and cycle performance of the battery can be further improved.

[0290] Figure 7 shows the X-ray diffraction (XRD) patterns of undoped LiMnPO4 and the cathode active material prepared in Example 2. As can be seen from the figure, the agreement between the main characteristic peak positions in the XRD of the cathode active material of Example 2 and that of undoped LiMnPO4 indicates that no impurity phase was introduced during the doping process, and the improvement in performance is mainly due to elemental doping and not due to impure phases. Figure 8 shows the X-ray energy dispersion spectrum (EDS) of the cathode active material prepared in Example 2. In the figure, the dots are the individual doping elements. From the figure, it can be seen that the elemental doping is uniform in the cathode active material of Example 2.

[0291] As can be seen from Table 6 above, assuming that the energy density and dynamic performance are not affected, the battery's cycle performance can be further improved by selecting an organopolysiloxane compound having one or more of the appropriate polar functional group content, number-average molecular weight, and addition amount and using it in combination with the positive electrode active material.

[0292] Examples 1, 28-32 show that as the amount of organopolysiloxane compound added increased, the powder resistance of the positive electrode active material composition initially decreased before increasing. This is because, within a certain range of organopolysiloxane compound addition, its hydrophobic properties reduce the interaction between conductive agents, alleviate aggregation of conductive agents, and allow for the formation of a better conductive network.

[0293] Furthermore, this application is not limited to the embodiments described above. The embodiments described above are illustrative, and any embodiment that has a configuration substantially identical to the technical idea and produces similar effects within the scope of the technical proposal of this application is included in the technical scope of this application. In addition, other forms constructed by adding various types of modifications to the embodiments that a person skilled in the art could conceive, without departing from the spirit of this application, and by combining some of the components of the embodiments are also included in the scope of this application. [Explanation of Symbols]

[0294] 1 Battery pack 2 Upper cabinet 3 Lower cabinet 4 Battery Modules 5 Secondary battery 51 cases 52 Electrode Assembly 53 Cover Plate

Claims

1. A positive electrode material composition comprising a positive electrode active material and an organopolysiloxane compound, 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 positive electrode active material is electrically neutral, wherein A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C comprises one or more elements selected from B (boron), S, Si, and N; D comprises one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1; x is selected from the range of 0.001 to 0.1; y is selected from the range of 0.001 to 0.5; z is selected from the range of 0.001 to 0.1; n is selected from the range of 0.001 to 0.1; and the positive electrode active material is electrically neutral. The organopolysiloxane compound comprises at least one structural unit represented by formula 1, 【Chemistry 1】 R １ and R ２ each independently represents at least one selected from the group consisting of -OH, -SH, an amino group, a phosphate ester group, a C1-C8 alkyl group, a C1-C8 halogenated alkyl group, a C1-C8 heteroalkyl group, a C1-C8 halogenated heteroalkyl group, a C2-C8 alkenyl group, a C2-C8 halogenated alkenyl group, or H, and is a positive electrode material composition.

2. The above a is selected from the range of 0.97 to 1.01 and / or The aforementioned x is selected from the range of 0.001 to 0.005, and / or The positive electrode material composition according to claim 1, wherein 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 one or more types selected from linear polysiloxanes and cyclic polysiloxanes.

4. The positive electrode material composition according to claim 3, wherein the linear polysiloxane further comprises a block group.

5. The linear polysiloxane comprises one or more of the following: polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polymethylhydrogensiloxane, carboxyl-functionalized polysiloxane, polymethylchloropropylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, mercaptopropylpolysiloxane, aminoethylaminopropylpolydimethylsiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, aminopropyl-terminated polydimethylsiloxane, terminal epoxypolysiloxane, terminal hydroxypolydimethylsiloxane, terminal polyetherpolydimethylsiloxane, side-chain aminopropylpolysiloxane, side-chain hydroxylmethylpolysiloxane, side-chain hydroxylpropylpolysiloxane, and / or, The positive electrode material composition according to claim 3, wherein the cyclic polysiloxane comprises one or more of the following: cyclic polydimethylsiloxane, cyclic polymethylvinylsiloxane, cyclic polymethylhydrogensiloxane, and cyclic polymethyltrifluoropropylsiloxane.

6. The cathode material composition according to claim 1, wherein the number average molecular weight of the organopolysiloxane compound is 300,000 or less.

7. The positive electrode material composition according to claim 4, wherein the mass percentage of polar functional groups in R1, R2 and the block group in the organopolysiloxane compound is α, and 0 ≤ α < 50%.

8. The cathode material composition according to claim 1, wherein the content of the organopolysiloxane compound is 0.01% to 2% by weight, and is calculated based on the total weight of the cathode material composition.

9. The positive electrode material composition according to claim 1, wherein the surface of the positive electrode active material is further coated with carbon.

10. The positive electrode material composition according to claim 1, wherein A, C, and D are each independently any element within their respective ranges, and B is at least two elements within that range.

11. The aforementioned z is selected from the range of 0.001 to 0.005, and / or The positive electrode material composition according to claim 1, wherein n is selected from the range of 0.001 to 0.

005.

12. The positive electrode material composition according to claim 1, wherein (1-y):y is in the range of 1:1 to 4:1, and a:x is in the range of 9:1 to 1100:

1.

13. The positive electrode active material is the positive electrode material composition according to claim 1, satisfying at least one of the following conditions (1) to (4). (1) The lattice change rate of the positive electrode active material is 8% or less, and the lattice change rate is expressed as (v0 - v1) / v0 × 100%, where v0 is the unit cell volume before charging and v1 is the unit cell volume after charging. (2) The Li / Mn antistructure defect concentration of the positive electrode active material is 2% or less. (3) The surface oxygen valency of the positive electrode active material is -1.82 or less. (4) The pressure density of the positive electrode active material at 3T (3 tons) is 2.0 g / cm³ ３ That's all.

14. The positive electrode material composition according to claim 1, further comprising a conductive agent and a binder.

15. The powder resistivity of the positive electrode material composition at 12 MPa is 4 Ω / cm to 50 Ω / cm, and / or, The specific surface area of ​​the aforementioned positive electrode material composition is 8 m². ２ / g to 20m ２ The positive electrode material composition according to claim 1, wherein the value is / g.

16. A method for preparing the positive electrode material composition according to claim 1, The process includes: (1) dissolving a manganese source, a source of element B, and an acid in a solvent and stirring to produce a suspension of element B-doped manganese salt, filtering the suspension to dry the cake and obtain an element B-doped manganese salt; (2) adding a lithium source, a phosphorus source, a source of element A, a source of element C, a source of element D, a solvent, and the element B-doped manganese salt obtained in step (1) to a reaction vessel and grinding and mixing to obtain a slurry; (3) transferring the slurry obtained in step (2) to a spray drying facility and spray drying and granulating to obtain particles; (4) sintering the particles obtained in step (3) to obtain a positive electrode active material; and (5) mixing the positive electrode active material obtained in step (4) with an organopolysiloxane compound, a binder, and a conductive agent to obtain a uniform 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 A method for preparing a positive electrode material composition wherein A comprises one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C comprises one or more elements selected from B (boron), S, Si, and N; D comprises one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1; x is selected from the range of 0.001 to 0.1; y is selected from the range of 0.001 to 0.5; z is selected from the range of 0.001 to 0.1; n is selected from the range of 0.001 to 0.1; and the positive electrode active material is electrically neutral.

17. The stirring in step (1) is carried out at a temperature in the range of 60 to 120°C, and / or The stirring in step (1) is carried out at a stirring speed of 200 to 800 rpm and / or, The polishing and mixing in step (2) above is carried out for 8 to 15 hours and / or, The method according to claim 16, wherein the sintering in step (4) is carried out at a temperature range of 600 to 900°C for 6 to 14 hours.

18. The method according to claim 16, further comprising adding a carbon source to the reaction vessel and polishing and mixing in step (2).

19. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises the positive electrode material composition described in claim 1, and the content of the positive electrode material composition in the positive electrode film layer is 50% by weight or more, calculated based on the total weight of the positive electrode film layer.

20. The solid-liquid contact angle between the positive electrode film layer and the non-aqueous organic solvent is between 3° and 90°, and / or The positive electrode sheet according to claim 19, wherein the porosity of the positive electrode film layer is 15% to 50%.

21. A secondary battery comprising a positive electrode material composition according to any one of claims 1 to 15, or a positive electrode sheet according to any one of claims 19 to 20.

22. A power consumption device including a secondary battery as described in claim 21.

Images