Positive electrode material and preparation method thereof, battery and electric device

Abstract

The invention provides a positive electrode material and a preparation method thereof, a battery and an electric device. The positive electrode material comprises a substrate and a coating layer, the coating layer coats at least one part of the surface of the substrate, the substrate comprises spinel lithium manganese oxide and layered lithium manganese oxide distributed on the surface layer of the spinel lithium manganese oxide, the chemical formula of the layered lithium manganese oxide comprises LicMndOe, c is greater than or equal to 1 and less than or equal to 3, c / d is greater than 0.5, (2e-c) / d is greater than or equal to 3 and less than or equal to 4, and the coating layer comprises a solid electrolyte.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular, to a cathode material, a preparation method thereof, a battery and an electrical device. Background Art

[0002] In recent years, with the increasingly wide application range of lithium-ion batteries, lithium-ion batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Due to the great development of lithium-ion batteries, higher requirements are also put forward for their performance. Subsequently, the market also puts forward more diverse requirements for cathode materials.

[0003] The spinel lithium manganese oxide cathode material has attracted much attention due to its advantages such as rich resources, low cost, good safety, and environmental friendliness, and is considered to be a promising cathode material. However, the spinel lithium manganese oxide has poor stability, resulting in the attenuation of battery capacity during the cycle process, which seriously hinders the exertion of its advantages. Therefore, the stability of the spinel lithium manganese oxide cathode material still needs to be improved. Summary of the Invention

[0004] The present application is made in view of the above problems, and its purpose is to provide a cathode material, a preparation method thereof, a battery and an electrical device. The cathode material has improved stability and reduced manganese dissolution amount, and thus has improved cycle performance.

[0005] To achieve the above object, a first aspect of the present application provides a cathode material, which includes a matrix and a coating layer. The coating layer covers at least a part of the surface of the matrix. The matrix includes spinel lithium manganese oxide and layered lithium manganese oxide distributed on the surface layer of the spinel lithium manganese oxide. The chemical formula of the layered lithium manganese oxide includes Li c Mn d O e , where 1≤c≤3, c / d>0.5, 3≤(2e-c) / d≤4, and the coating layer includes a solid electrolyte.

[0006] In the cathode material, the layered lithium manganese oxide Li c Mn d O e is an electrochemically inert phase, and its two-dimensional layered structure can support the structure after lithium deintercalation and intercalation of the three-dimensional spinel lithium manganese oxide, thereby stabilizing the matrix structure. The layered lithium manganese oxide Li c Mn d O eDistributed on the surface of the spinel lithium manganese oxide, it can reduce the content of unstable manganese on the surface of the matrix and inhibit the dissolution of unstable manganese on the surface of the matrix into the electrolyte. The positive electrode material includes a solid electrolyte as a coating layer, which can play the role of intercepting the dissolution of manganese ions in the outermost layer, and can also effectively improve the lithium ion conduction, so that the rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide. Thus, the positive electrode material has improved stability, reduced manganese dissolution amount, and further improved cycle performance.

[0007] In some embodiments, in the X-ray diffraction pattern of the positive electrode material, it includes a first diffraction peak of the (020) crystal plane of the layered lithium manganese oxide with a 2θ diffraction angle between 20° and 23°, and a second diffraction peak of the (111) crystal plane of the spinel lithium manganese oxide with a 2θ diffraction angle between 16° and 20°.

[0008] In some embodiments, in the X-ray diffraction pattern of the positive electrode material, it includes a first diffraction peak of the (020) crystal plane of the layered lithium manganese oxide with a 2θ diffraction angle between 20° and 23°, a third diffraction peak of the (-111) crystal plane of the layered lithium manganese oxide with a 2θ diffraction angle between 20° and 23°, and a second diffraction peak of the (111) crystal plane of the spinel lithium manganese oxide with a 2θ diffraction angle between 16° and 20°.

[0009] Through the first diffraction peak, the second diffraction peak, and the optional third diffraction peak, it can be verified whether there is an electrochemically inert phase layered lithium manganese oxide in the positive electrode material, and the ratio of the layered lithium manganese oxide to the spinel lithium manganese oxide can also be verified through their peak areas.

[0010] In some embodiments, the ratio of the peak area of the first diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.2.

[0011] In some embodiments, the ratio of the peak area of the first diffraction peak to the peak area of the second diffraction peak is 0.01 to 0.14.

[0012] In some embodiments, the ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.2.

[0013] In some embodiments, the ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak is 0.01 to 0.14.

[0014] By selecting the ratio of the peak areas of the first diffraction peak and the second diffraction peak, optionally the ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak, it is beneficial to better realize the stable matrix structure of the layered lithium manganese oxide and / or inhibit Mn2+ The balance between the effect of ion dissolution and the rate performance of the positive electrode material.

[0015] In some embodiments, the chemical formula of the layered lithium manganese oxide includes Li2MnO3.

[0016] In some embodiments, the chemical formula of the matrix includes Li a Mn 2-b M b O 4-z X z , where 1 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.5, 0 ≤ z ≤ 0.1; M includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Ti, Li, W; X includes at least one of S, F, Cl.

[0017] In some embodiments, the chemical formula of the matrix includes Li a Mn 2-b M b O 4-z X z , where 1 ≤ a ≤ 1.2, 0 < b ≤ 0.3, 0 ≤ z ≤ 0.1; M includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Ti, Li, W; X includes at least one of S, F, Cl.

[0018] Through the matrix with the above chemical formula, the stability of the positive electrode material can be further improved and / or its manganese dissolution amount can be reduced.

[0019] In some embodiments, the solid electrolyte includes at least one of a compound with the chemical formula A x B y C m , an alkali metal bis(trifluoromethanesulfonyl)imide salt or an alkali metal bis(fluorosulfonyl)imide salt. In the compound A x B y C m , 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8; A includes at least one of Li, Na, K; B includes at least one of La, Ce, Zr, Ti, Bi, In, Al, Y, Er, Nb; C includes at least one of F, Cl, Br, I, S.

[0020] In some embodiments, the solid electrolyte includes one or more of a compound with the chemical formula Li x B y C m , a lithium bis(trifluoromethanesulfonyl)imide salt or a lithium bis(fluorosulfonyl)imide salt. In the Li x By C m In the compound of m , 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8; B includes at least one of Zr, Al, In, Y, Ti, and La; C includes at least one of F, Cl, Br, and I.

[0021] The above solid electrolyte has high ionic conductivity. Thus, while intercepting the dissolution of manganese ions, it can effectively improve lithium ion conduction, so that the rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide.

[0022] The second aspect of the present application provides a method for preparing a cathode material, including:

[0023] At least mixing a first lithium source and a manganese source to obtain a first mixed material, and performing a first sintering on the first mixed material to obtain a first sintered product;

[0024] Mixing the obtained first sintered product with a second lithium source to obtain a second mixed material, and performing a second sintering on the second mixed material to obtain a matrix;

[0025] Coating the matrix with a coating material to obtain a cathode material, wherein the coating material includes a solid electrolyte,

[0026] Wherein, the cathode material includes a matrix and a coating layer. The coating layer coats at least a part of the surface of the matrix. The matrix includes spinel lithium manganese oxide and layered lithium manganese oxide distributed on the surface layer of the spinel lithium manganese oxide. The chemical formula of the layered lithium manganese oxide includes Li c Mn d O e , where 1 ≤ c ≤ 3, c / d > 0.5, 3 ≤ (2e - c) / d ≤ 4, and the coating layer includes a solid electrolyte.

[0027] The cathode material obtained by the above method has improved stability and reduced manganese dissolution amount, and thus has improved cycle performance.

[0028] In some embodiments, an M source and / or an X source are further mixed in the first mixed material and / or the second mixed material. The M element in the M source includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Li, Ti, and W; the X element in the X source includes at least one of S, F, and Cl.

[0029] In some embodiments, an M source and / or an X source are mixed in the first mixed material. Based on the molar amounts of lithium element, manganese element, M element, and X element, the mixing ratio of the first lithium source, manganese source, M source, and X source is 0.95 - 1.2:1.5 - 2:0 - 0.5:0 - 0.1.

[0030] In some embodiments, an M source and / or an X source are mixed in the first mixed material. Based on the molar amounts of lithium element, manganese element, M element, and X element, the mixing ratio of the first lithium source, manganese source, M source, and X source is 0.95 - 1.2:1.7 - 2:0.0001 - 0.3:0 - 0.1.

[0031] Thereby, the stability of the obtained cathode material can be further improved and / or the manganese dissolution amount thereof can be reduced.

[0032] In some embodiments, the coating material includes at least one of a compound with the chemical formula A x B y C m , an alkali metal bis(trifluoromethanesulfonyl)imide salt, or an alkali metal bis(fluorosulfonyl)imide salt. In the compound with the chemical formula A x B y C m , 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8; A includes at least one of Li, Na, and K; B includes at least one of La, Ce, Zr, Ti, Bi, In, Al, Y, Er, and Nb; C includes at least one of F, Cl, Br, I, and S.

[0033] The above coating material has high ionic conductivity. Thereby, while intercepting the dissolution of manganese ions, it can effectively improve lithium ion conduction, so that the rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide.

[0034] In some embodiments, based on the molar amount of lithium element, the ratio of the addition amount of the second lithium source to the first lithium source is ω, where 0 < ω < 0.2.

[0035] In some embodiments, based on the molar amount of lithium element, the ratio of the addition amount of the second lithium source to the first lithium source is ω, where 0.0005 ≤ ω ≤ 0.1.

[0036] By selecting the ratio of the addition amount of the second lithium source to the first lithium source, it is beneficial to form a more appropriate amount of layered lithium manganese oxide, thereby facilitating a better balance between the role of stabilizing the matrix structure of the layered lithium manganese oxide and / or inhibiting Mn 2+ ion dissolution and the rate performance of the cathode material.

[0037] In some embodiments, in the step of coating the matrix with the coating material, the mass of the coating material is 0.1% - 5% of the mass of the matrix.

[0038] Selecting the addition amount of the coating material is beneficial to form a more appropriate coating layer, thereby enabling better realization of its role in intercepting manganese ion dissolution and / or improving lithium ion conduction.

[0039] In some embodiments, the method satisfies one or more of the following conditions:

[0040] (1) The temperature of the first sintering is 600°C to 800°C;

[0041] (2) The time of the first sintering is 8h to 20h;

[0042] (3) The temperature of the second sintering is 450°C to 800°C;

[0043] (4) The time of the second sintering is 4h to 12h.

[0044] The third aspect of the present application provides a battery, including the positive electrode material of the first aspect of the present application or the positive electrode material prepared by the preparation method of the second aspect of the present application.

[0045] Thus, the battery of the embodiments of the present application has improved cycle performance.

[0046] The fourth aspect of the present application provides an electrical device, including the battery described in the third aspect of the present application.

[0047] Thus, the electrical device of the embodiments of the present application has corresponding technical advantages to those of the battery.

[0048] The present application provides a positive electrode material including a matrix and a coating layer. This positive electrode material has improved stability and reduced manganese dissolution amount, and thus has improved cycle performance.

[0049] In the matrix of the positive electrode material, layered lithium manganese oxide Li c Mn d O e is distributed on the surface layer of the spinel lithium manganese oxide. The layered lithium manganese oxide Li c Mn d O e is an electrochemically inert phase, and its two-dimensional layered structure can support the structure of the three-dimensional spinel lithium manganese oxide after lithium deintercalation and intercalation. Thereby, the matrix structure can be stabilized, the fragmentation of the matrix can be inhibited, and its stability during charge and discharge can be improved, and further the cycle stability of the positive electrode material can be improved. In addition, the layered lithium manganese oxide Li c Mn d O e is distributed on the surface layer of the matrix, which can reduce the content of unstable manganese on the surface layer of the matrix and inhibit the dissolution of unstable manganese on the surface layer of the matrix into the electrolyte.

[0050] In addition, a coating layer is coated on at least a part of the surface of the cathode material matrix, and the coating layer includes a solid electrolyte. The coating layer can play a role in intercepting the dissolution of manganese ions in the outermost layer, and at the same time can effectively improve lithium ion conduction, so that the rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide. In addition, the coating layer can inhibit the corrosion of the electrolyte on the cathode material matrix and reduce the loss of the electrolyte caused by side reactions.

[0051] The present application also provides a method for preparing a cathode material. In this method, a first sintered product is obtained by sintering a mixed material including a first lithium source and a manganese source; and a matrix is obtained by sintering a mixed material including the first sintered product and a second lithium source; and then the matrix is coated to obtain a cathode material including the matrix and a coating layer. The cathode material obtained thereby has improved stability and reduced manganese dissolution amount, and thus has improved cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The scanning electron microscope image (SEM image) of the cathode material prepared in Example 1 is shown.

[0053] Figure 2 The cross-sectional scanning electron microscope image and the element distribution table of the cathode material prepared in Example 1 are shown.

[0054] Figure 3 The X-ray diffraction pattern (XRD pattern) of the cathode material prepared in Example 1 is shown.

[0055] Figure 4 The charge-discharge curve of the cathode material prepared in Example 1 at 0.1C from 3.0 V to 4.8 V is shown.

[0056] Figure 5 It is a schematic diagram of a battery cell according to an embodiment of the present application.

[0057] Figure 6 is Figure 5 The exploded view of the battery cell according to an embodiment of the present application shown.

[0058] Figure 7 It is a schematic diagram of a battery module according to an embodiment of the present application.

[0059] Figure 8 It is a schematic diagram of a battery pack according to an embodiment of the present application.

[0060] Figure 9 is Figure 8 The exploded view of the battery pack according to an embodiment of the present application shown.

[0061] Figure 10 It is a schematic diagram of an electrical device using the battery according to an embodiment of the present application as a power source.

[0062] Description of reference numerals:

[0063] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery; 51 shell; 52 electrode assembly; 53 top cover assembly DETAILED DESCRIPTION

[0064] Hereinafter, the embodiments of the positive electrode material and preparation method thereof, battery and electric device of the present application are specifically disclosed in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0065] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0066] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0067] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0068] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0069] With the continuous development of the new energy industry, the market has put forward more diverse requirements for cathode materials. Among them, spinel lithium manganese oxide cathode materials have attracted much attention due to their advantages such as rich resources, low cost, good safety, and environmental friendliness, and are considered to be a more promising cathode material. However, the poor stability of spinel lithium manganese oxide leads to the attenuation of battery capacity during the cycling process, thus seriously hindering the exertion of its advantages. The main reason lies in the serious manganese dissolution during charge and discharge, which leads to the Jahn-Teller effect and the loss of active substances.

[0070] Therefore, the problem of how to provide a spinel lithium manganese oxide cathode material with stable structure and effective suppression of manganese dissolution still needs to be further solved.

[0071] Based on this, this application proposes a cathode material, its preparation method, battery and electrical device. The present invention and exemplary embodiments will be described in more detail below.

[0072] Cathode material

[0073] This application provides a cathode material. The cathode material includes a matrix and a coating layer, the coating layer covers at least a part of the surface of the matrix, the matrix includes spinel lithium manganese oxide and layered lithium manganese oxide distributed on the surface layer of the spinel lithium manganese oxide, and the chemical formula of the layered lithium manganese oxide includes Li c Mn d O e , where 1≤c≤3, c / d>0.5, 3≤(2e-c) / d≤4, and the coating layer includes a solid electrolyte.

[0074] In the matrix of this cathode material, layered lithium manganese oxide Li c Mn d O e is distributed on the surface layer of the spinel lithium manganese oxide. Here, the meaning of "distribution" includes but is not limited to layered lithium manganese oxide Li c Mn d O eExist continuously and / or discontinuously on the surface layer of the spinel lithium manganese oxide in the form of, for example, dot-like, patch-like, island-like, flake-like, rod-like, etc. "Distributed on the surface layer of the spinel lithium manganese oxide" includes that the layered lithium manganese oxide exists in and / or on the outer surface layer of the spinel lithium manganese oxide. In terms of the bulk phase, the layered lithium manganese oxide exists in the bulk phase of the spinel lithium manganese oxide, but is not limited thereto. The layered lithium manganese oxide Li c Mn d O e is an electrochemically inert phase and does not participate in the electrochemical reaction during the charge and discharge process (<4.5V) of the positive electrode material. Its two-dimensional layered structure can support the structure of the three-dimensional spinel lithium manganese oxide after lithium deintercalation and intercalation. Thereby, the matrix structure can be stabilized, the matrix fragmentation can be inhibited, and its stability during the charge and discharge process can be improved, and further the cycle stability of the positive electrode material can be improved.

[0075] Utilize the property that the layered lithium manganese oxide Li c Mn d O e does not participate in the electrochemical reaction during the charge and discharge process of <4.5V, and the existence of the layered lithium manganese oxide Li c Mn d O e in the positive electrode material can be verified. By adjusting the upper limit voltage of the positive electrode material to 4.8V and observing whether there is a charging plateau above 4.5V in the first charge-discharge curve, the existence of Li c Mn d O e in the positive electrode material can be verified. If a charging plateau above 4.5V appears, it indicates the existence of Li c Mn d O e in the positive electrode material. If no charging plateau above 4.5V appears, it indicates the non-existence of Li c Mn d O e in the positive electrode material.

[0076] It has been found that the Mn generated by manganese dissolution 2+ can escape into the electrolyte through the lithium ion transport channels in the spinel lithium manganese oxide. In the spinel lithium manganese oxide, the lithium ion transport channels are three-dimensional structures. However, in the layered lithium manganese oxide, the lithium ion transport channels are two-dimensional structures. In the positive electrode material of the embodiment of the present application, since the layered lithium manganese oxide Li c Mn d O e is distributed on the surface layer of the spinel lithium manganese oxide, the lithium ion transport channels will change from three-dimensional structures to two-dimensional structures. Thereby, the two-dimensional lithium ion transport channels effectively inhibit the Mn generated in the spinel lithium manganese oxide2+ Ions are transported through the surface layer of the matrix into the electrolyte. That is, layered lithium manganese oxide Li c Mn d O e can inhibit the transport of Mn 2+ ions generated in spinel lithium manganese oxide and prevent them from dissolving into the electrolyte.

[0077] The positive electrode material of the embodiment of the present application further includes a coating layer. The coating layer covers at least a part or all of the surface of the matrix. The coating layer can inhibit the ion conduction generated inside the matrix, thereby directly preventing Mn 2+ from entering the electrolyte, and playing a role in intercepting the dissolution of manganese ions in the outermost layer. In addition, the coating layer can inhibit the corrosion of the positive electrode material matrix by the electrolyte, help improve the stability of the positive electrode material, and at the same time reduce the loss of the electrolyte caused by side reactions. The coating layer includes a solid electrolyte. The solid electrolyte has high ionic conductivity and can effectively improve lithium ion conduction, so that the battery rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide Li 2+ Mn c Mn d O e .

[0078] The matrix can be doped or undoped. Optionally, the matrix is doped. When the matrix is doped, the doping element in the matrix can inhibit the Jahn-Teller effect during the charge and discharge process of the positive electrode material, improve the stability of the matrix crystal structure, and reduce the dissolution of manganese (i.e., inhibit 2Mn 3+ →Mn 2+ +Mn 4+ ), and inhibit the generation of Mn 2+ from the source. Exemplarily, the doping can be manganese-site doping or oxygen-site doping, but is not limited thereto. For manganese-site doping, the doping element can be other elements except manganese. Exemplarily, the manganese-site doping elements can include at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Ti, Li, W, but is not limited thereto. For oxygen-site doping, the doping element can be other elements except oxygen. Exemplarily, the oxygen-site doping elements can include at least one of S, F, Cl.

[0079] In some embodiments, the chemical formula of the positive electrode material matrix includes Li a Mn 2-b M b O 4-z X z, where 1 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.5, 0 ≤ z ≤ 0.1. Optionally, 1.01 ≤ a ≤ 1.19. Optionally, 0.0001 ≤ b ≤ 0.5. Optionally, 0.0001 ≤ z ≤ 0.1. For example, a can be 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19 or 1.2. For example, b can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5. For example, z can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1. In some embodiments, the chemical formula of the matrix includes Li a Mn 2-b M b O 4-z X z , where 1 ≤ a ≤ 1.2, 0 < b ≤ 0.3, 0 ≤ z ≤ 0.1. M includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Li, Ti, W. Optionally, M includes at least one of Ni, Al, Nb, Ti, Zr. Optionally, M includes Al. X includes at least one of S, F, Cl. Optionally, X includes at least one of F, Cl.

[0080] In the above chemical formula, "M" represents the doping element at the manganese site. Optionally, the matrix includes the doping element M at the manganese site, thereby suppressing the Jahn-Teller effect during charge and discharge, improving the stability of the matrix crystal structure, and reducing the dissolution of manganese (i.e., suppressing 2Mn 3+ →Mn 2+ +Mn 4+ ), and suppressing the generation of Mn 2+ from the source.

[0081] In the above chemical formula, "X" represents the doping element at the oxygen site. Optionally, the matrix can include the doping element X at the oxygen site, thereby suppressing the Jahn-Teller effect during charge and discharge, improving the stability of the matrix crystal structure, and reducing the dissolution of manganese (i.e., suppressing 2Mn 3+ →Mn 2+ +Mn 4+ ), and suppressing the generation of Mn 2+ from the source.

[0082] In some embodiments, the solid electrolyte includes a chemical formula of A x By C m at least one of a compound, an alkali metal bis(trifluoromethanesulfonyl)imide salt, or an alkali metal bis(fluorosulfonyl)imide salt.

[0083] In the A x B y C m compound, 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8. Exemplarily, x can be 1, 2, 3, or 4; y can be 1, 2, or 3; m can be 1, 2, 3, 4, 5, 6, 7, or 8. A includes at least one of Li, Na, and K. Optionally, A includes Li. B includes at least one of La, Ce, Zr, Ti, Bi, In, Al, Y, Er, and Nb. Optionally, B includes at least one of Zr, Al, In, Y, Ti, and La. Optionally, B includes at least one of Zr, Al, and Y. C includes at least one of F, Cl, Br, I, and S. Optionally, C includes at least one of F, Cl, Br, and I. Optionally, C includes at least one of Cl or Br.

[0084] The alkali metal includes at least one of Li, Na, K, Rb, and Cs. Optionally, the alkali metal includes at least one of Li, Na, and K.

[0085] The alkali metal bis(trifluoromethanesulfonyl)imide salt or the alkali metal bis(fluorosulfonyl)imide salt is an ionic electrolyte that can improve ionic conductivity and stabilize the lithium-ion electrolyte interface.

[0086] In some embodiments, the solid electrolyte includes one or more of a compound having the chemical formula Li x B y C m , lithium bis(trifluoromethanesulfonyl)imide salt, or lithium bis(fluorosulfonyl)imide salt. In the Li x B y C m compound, 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8; B includes at least one of Zr, Al, In, Y, Ti, and La, optionally, B includes at least one of Zr, Al, and Y; C includes at least one of F, Cl, Br, and I, optionally, C includes at least one of Cl or Br.

[0087] In some embodiments, the solid electrolyte can include LiZrCl5, Li 1.5 ZrCl 5.5 , Li 2.5 ZrCl 6.5, one or more of Li3ZrCl7, LiAlCl4, Li3InCl6, Li3YCl6, Li3AlF6, LiYF4, Li2TiF6, Li3YBr6, Li3LaBr6, Li3InBr6, LiInI4, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or lithium bis(fluorosulfonyl)imide (LiFSI). Optionally, the solid electrolyte may include one or more of LiZrCl5, Li3ZrCl7, LiAlCl4, Li3YBr6, lithium bis(trifluoromethanesulfonyl)imide or lithium bis(fluorosulfonyl)imide.

[0088] The above solid electrolyte has high ionic conductivity, which can effectively improve lithium ion conduction, so that the battery rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide Li c Mn d O e .

[0089] In some embodiments, in the X-ray diffraction pattern of the positive electrode material, it includes a first diffraction peak of the (020) crystal plane of the layered lithium manganese oxide between 2θ diffraction angles of 20° to 23°, and a second diffraction peak of the (111) crystal plane of the spinel lithium manganese oxide between 2θ diffraction angles of 16° to 20°; optionally, it includes a third diffraction peak of the (-111) crystal plane of the layered lithium manganese oxide between 2θ diffraction angles of 20° to 23°.

[0090] The first diffraction peak between 2θ diffraction angles of 20° to 23° corresponds to the (020) crystal plane of the electrochemically inert phase layered lithium manganese oxide, and the third diffraction peak between 2θ diffraction angles of 20° to 23° corresponds to the (-111) crystal plane of the electrochemically inert phase layered lithium manganese oxide, belonging to the C / 2m space group. The second diffraction peak between 2θ diffraction angles of 16° to 20° corresponds to the (111) crystal plane of the spinel lithium manganese oxide. The second diffraction peak is the strongest characteristic peak between 2θ diffraction angles of 16° to 20°. In addition to verifying the presence or absence of the layered lithium manganese oxide Li c Mn d O e in the positive electrode material by observing whether there is a charging platform above 4.5V in the first charge-discharge curve as described above, it can also be verified by whether there are the first diffraction peak and the optional third diffraction peak between 2θ diffraction angles of 20° to 23° in the X-ray diffraction pattern of the positive electrode material.

[0091] In some embodiments, the ratio of the peak area of the first diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.2, optionally 0.01 to 0.16, optionally 0.01 to 0.14, and optionally 0.02 to 0.14. For example, it can be 0.001, 0.005, 0.008, 0.01, 0.012, 0.02, 0.029, 0.03, 0.04, 0.045, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.134, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19 or 0.2. In some embodiments, the ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.2, optionally 0.01 to 0.16, optionally 0.01 to 0.14, and optionally 0.02 to 0.14. For example, it can be 0.001, 0.005, 0.008, 0.01, 0.012, 0.02, 0.029, 0.03, 0.04, 0.045, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.134, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19 or 0.2.

[0092] The ratio of the peak area of the first diffraction peak to the peak area of the second diffraction peak or the ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak represents the proportion of layered lithium manganese oxide Li c Mn d O e in the matrix relative to spinel lithium manganese oxide. Keeping the proportion of layered lithium manganese oxide Li c Mn d O e within the above range is beneficial to the layered lithium manganese oxide Li c Mn d O e acting as an inert phase to stabilize the matrix structure and inhibit the transport of Mn 2+ ions in the spinel lithium manganese oxide through the surface layer of the matrix into the electrolyte, thereby improving the cycle performance of the battery. At the same time, it will not have an adverse impact on the rate performance of the positive electrode material due to the inert phase layered lithium manganese oxide Li c Mn d O e .

[0093] In some embodiments, the chemical formula of the layered lithium manganese oxide includes Li2MnO3.

[0094] In some embodiments, the thickness of the coating layer is denoted as d1, and the diameter of the positive electrode material particles is denoted as D1, where 0 < d1 / D1 ≤ 0.05.

[0095] The positive electrode material of the embodiments of the present application may be in the form of particles, but is not limited thereto. The diameter of the positive electrode material particles can be measured by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). Exemplarily, the diameter of the positive electrode material particles can be 2 - 30 μm, optionally 2 - 20 μm, optionally 7 - 15 μm, but is not limited thereto.

[0096] The thickness of the coating layer can be measured by transmission electron microscopy (TEM). Exemplarily, the thickness at multiple points of a single particle can be tested by TEM, and the average value is taken. By maintaining the thickness of the coating layer on the surface of the substrate within the above range, the coating layer can more effectively inhibit manganese dissolution, and at the same time, the rate performance of the positive electrode material can be maintained or improved.

[0097] Preparation method of the positive electrode material

[0098] The present application also provides a preparation method of a positive electrode material. The method includes the following steps.

[0099] At least mix a first lithium source and a manganese source to obtain a first mixed material, and perform a first sintering on the first mixed material to obtain a first sintered product.

[0100] Mix the obtained first sintered product with a second lithium source to obtain a second mixed material, and perform a second sintering on the second mixed material to obtain a substrate.

[0101] Coat the substrate with a coating material to obtain a positive electrode material, wherein the coating material includes a solid electrolyte.

[0102] The positive electrode material includes a substrate and a coating layer. The coating layer coats at least a part of the surface of the substrate. The substrate includes spinel lithium manganese oxide and layered lithium manganese oxide distributed on the surface layer of the spinel lithium manganese oxide. The chemical formula of the layered lithium manganese oxide includes Li c Mn d O e , where 1 ≤ c ≤ 3, c / d > 0.5, 3 ≤ (2e - c) / d ≤ 4, and the coating layer includes a solid electrolyte.

[0103] In some embodiments, in the first mixed material, based on the molar amounts of lithium element and manganese element, the mixing ratio of the first lithium source and the manganese source can be 0.95 - 1.2:2, but is not limited thereto.

[0104] In some embodiments, in the X-ray diffraction pattern of the positive electrode material, there are a first diffraction peak of a layered lithium manganese oxide (020) plane with a 2θ diffraction angle between 20° and 23°, and a second diffraction peak of a spinel lithium manganese oxide (111) plane with a 2θ diffraction angle between 16° and 20°. In some embodiments, in the X-ray diffraction pattern of the positive electrode material, there is a third diffraction peak of a layered lithium manganese oxide (-111) plane with a 2θ diffraction angle between 20° and 23°.

[0105] In some embodiments, the ratio of the peak area of the first diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.2, optionally 0.01 to 0.14. In some embodiments, the ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.2, optionally 0.01 to 0.14.

[0106] In some embodiments, the chemical formula of the layered lithium manganese oxide includes Li2MnO3.

[0107] In the preparation method of the embodiments of the present application, the first lithium source and the second lithium source may be the same or different. The first lithium source or the second lithium source may include lithium-containing substances known in the art for preparing lithium manganese oxides. As an example, the first lithium source or the second lithium source may independently include one or more of elemental lithium, lithium carbonate, lithium hydroxide, lithium oxide, lithium sulfate, lithium nitrate, lithium oxalate, lithium acetate, lithium phosphate, lithium dihydrogen phosphate, or lithium tungstate, but is not limited thereto. Optionally, the first lithium source or the second lithium source may independently include one or more of lithium carbonate, lithium hydroxide, lithium oxide, and lithium sulfate, but is not limited thereto.

[0108] The manganese source may include manganese-containing substances known in the art for preparing lithium manganese oxides. As an example, the manganese source may include one or more of elemental manganese, manganese dioxide, such as electrolytic manganese dioxide, manganese trioxide, manganese tetroxide, manganese phosphate, manganese oxalate, manganese acetate, and manganese carbonate, but is not limited thereto. Optionally, the manganese source may include one or more of electrolytic manganese dioxide and manganese tetroxide.

[0109] In this method, a first sintered product is obtained by sintering a mixed material including a first lithium source and a manganese source; a matrix is obtained by sintering a mixed material including the first sintered product and a second lithium source; and then the matrix is coated to obtain a cathode material including the matrix and a coating layer. Among them, the first sintered product has a spinel structure. In the second sintering process, the first sintered product with a spinel structure is mixed with the second lithium source, so that the first sintered product undergoes the second sintering under lithium-rich conditions. Lithium from the second lithium source enters the surface layer of the first sintered product with a spinel structure, causing the material with a spinel structure to form a lithium-rich phase, and the crystal form of a part of the material changes from spinel type to layered type. Thus, layered lithium manganese oxide is formed on the surface layer of the first sintered product with a spinel structure to obtain the matrix.

[0110] The layered lithium manganese oxide Li formed on the surface layer of spinel lithium manganese oxide c Mn d O e is an electrochemically inert phase and does not participate in the electrochemical reaction during the charge and discharge process (<4.5V) of the cathode material. Its two-dimensional layered structure can support the structure after lithium deintercalation and intercalation of the three-dimensional spinel lithium manganese oxide. Thus, the matrix structure can be stabilized, the fragmentation of the matrix can be inhibited, and its stability during the charge and discharge process can be improved, thereby improving the cycle stability of the cathode material. Moreover, the layered lithium manganese oxide Li c Mn d O e can inhibit the transport of Mn 2+ ions generated in the spinel lithium manganese oxide and prevent them from dissolving into the electrolyte.

[0111] In the method, it further includes coating the matrix with a coating material, where the coating material includes a solid electrolyte.

[0112] The so-called coating material includes a material used to coat the matrix to form a coating layer on at least a part or all of the surface of the matrix. By forming a coating layer on the surface of the matrix, the ionic conduction of Mn 2+ generated inside the matrix can be inhibited, thereby directly preventing Mn 2+ from entering the electrolyte and playing the role of intercepting the dissolution of manganese ions in the outermost layer. The solid electrolyte included in the coating material has high ionic conductivity, which can effectively improve the lithium ion conduction, so that the battery rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide Li c Mn d O e .

[0113] The coating can be carried out using common coating methods in the art, for example, dry solid-phase ball milling, but not limited thereto.

[0114] In some embodiments, the first mixed material and / or the second mixed material are optionally further mixed with a doping element source. In this way, a doped matrix is formed. The doping element in the matrix can inhibit the Jahn-Teller effect during the charge and discharge process of the cathode material, improve the stability of the crystal structure of the matrix, and reduce the dissolution of manganese (i.e., inhibit 2Mn 3+ →Mn 2+ +Mn 4+ ), and inhibit the generation of Mn 2+ from the source. Exemplarily, the doping element can be a manganese-site doping element or an oxygen-site doping element, but is not limited thereto. For the manganese-site doping element, it can be other elements except manganese. Exemplarily, the manganese-site doping element can include at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Ti, Li, W, but is not limited thereto. For the oxygen-site doping element, it can be other elements except oxygen. Exemplarily, the oxygen-site doping element can include at least one of S, F, Cl.

[0115] In some embodiments, an M source and / or an X source are optionally further mixed in the first mixed material and / or the second mixed material. The M element in the M source includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Li, Ti, W. The X element in the X source includes at least one of S, F, Cl.

[0116] In some embodiments, an M source and / or an X source are optionally mixed in the first mixed material. Based on the molar amounts of lithium element, manganese element, M element, and X element, the mixing ratio of the first lithium source, manganese source, M source, and X source is 0.95 - 1.2:1.5 - 2:0 - 0.5:0 - 0.1, optionally 0.95 - 1.2:1.7 - 2:0.0001 - 0.3:0 - 0.1; wherein the M element includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Li, Ti, W; and the X element includes at least one of S, F, Cl.

[0117] In some embodiments, an M source is mixed in the first mixed material. Based on the molar amounts of lithium element, manganese element, and M element, the mixing ratio of the first lithium source, manganese source, and M source is 0.95 - 1.2:1.5 - 2:0.0001 - 0.5, optionally 0.95 - 1.2:1.7 - 2:0.0001 - 0.3, optionally 0.95 - 1.2:1.7 - 1.95:0.05 - 0.3.

[0118] In some embodiments, an M source and an X source are optionally mixed in the first mixed material. Based on the molar amounts of lithium, manganese, M, and X elements, the mixing ratio of the first lithium source, manganese source, M source, and X source is 0.95 to 1.2:1.5 to 2:0.0001 to 0.5:0.0001 to 0.1, optionally 0.95 to 1.2:1.7 to 2:0.0001 to 0.3:0.0001 to 0.1.

[0119] "M" represents an element doped at the manganese site. The M source may include one or more of elemental M or oxides, hydroxides, nitrates, sulfates, hydrochlorides, carbonates, phosphates, acetates, oxalates of element M, but is not limited thereto. For example, the M source may include oxides of element M, such as vanadium pentoxide, technetium heptoxide, cobalt tetroxide, cobaltous oxide, nickel oxide, magnesium oxide, ferrous oxide, aluminum oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, niobium pentoxide, molybdenum oxide, chromium oxide, titanium oxide, tungsten oxide, but is not limited thereto. Optionally, the M source includes one or more of nickel oxide (NiO), aluminum oxide (Al2O3), niobium pentoxide (Nb2O5), titanium oxide (TiO2), zirconium oxide (ZrO2).

[0120] "X" represents an element doped at the oxygen site. The X source may include one or more of elemental S, lithium fluoride, sodium fluoride, potassium fluoride, ammonium fluoride, lithium chloride, sodium chloride, potassium chloride, aluminum trichloride, magnesium chloride, but is not limited thereto.

[0121] At least one of the M source or the X source may be mixed in the first mixed material. At least one of the M source or the X source may also not be mixed in the first mixed material. At least one of the M source or the X source may be mixed in the second mixed material. At least one of the M source or the X source may also not be mixed in the second mixed material. Optionally, at least one of the M source or the X source is mixed in the first mixed material; additionally or alternatively, at least one of the M source or the X source is mixed in the second mixed material. Optionally, the M source is mixed in the first mixed material; additionally or alternatively, the M source is mixed in the second mixed material. Optionally, the M source is mixed in the first mixed material.

[0122] When the M source and / or the X source are mixed in the first mixed material and / or the second mixed material, lithium manganese oxide containing the manganese-site doped element M and / or the oxygen-site doped element X can be obtained by sintering, thereby suppressing the Jahn-Teller effect during the charge and discharge process of the cathode material, improving the stability of the matrix crystal structure, and reducing the dissolution of manganese (i.e., suppressing 2Mn 3+ →Mn 2+ +Mn 4+ ), and suppressing the generation of Mn 2+ from the source.

[0123] In some embodiments, the solid electrolyte includes at least one of a compound having the chemical formula A x B y C m , an alkali metal bis(trifluoromethanesulfonyl)imide salt, or an alkali metal bis(fluorosulfonyl)imide salt.

[0124] In the compound having the chemical formula A x B y C m , 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, and 1 ≤ m ≤ 8. Exemplarily, x can be 1, 2, 3, or 4; y can be 1, 2, or 3; and m can be 1, 2, 3, 4, 5, 6, 7, or 8. A includes at least one of Li, Na, and K. Optionally, A includes Li. B includes at least one of La, Ce, Zr, Ti, Bi, In, Al, Y, Er, and Nb. Optionally, B includes at least one of Zr, Al, In, Y, Ti, and La. Optionally, B includes at least one of Zr, Al, and Y. C includes at least one of F, Cl, Br, I, and S. Optionally, C includes at least one of F, Cl, Br, and I. Optionally, C includes at least one of Cl and Br.

[0125] The alkali metal includes at least one of Li, Na, K, Rb, and Cs. Optionally, the alkali metal includes at least one of Li, Na, and K.

[0126] The alkali metal bis(trifluoromethanesulfonyl)imide salt or the alkali metal bis(fluorosulfonyl)imide salt is an ionic electrolyte that can improve the ionic conductivity and stabilize the lithium ion electrolyte interface.

[0127] In some embodiments, the solid electrolyte includes one or more of a compound having the chemical formula Li x B y C m , lithium bis(trifluoromethanesulfonyl)imide salt, or lithium bis(fluorosulfonyl)imide salt. In the Li x B y C m compound, 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, and 1 ≤ m ≤ 8; B includes at least one of Zr, Al, In, Y, Ti, and La, and optionally, B includes at least one of Zr, Al, and Y; C includes at least one of F, Cl, Br, and I, and optionally, C includes at least one of Cl and Br.

[0128] In some embodiments, the solid electrolyte may include LiZrCl5, Li 1.5 ZrCl 5.5 , Li 2.5 ZrCl 6.5, one or more of Li3ZrCl7, LiAlCl4, Li3InCl6, Li3YCl6, Li3AlF6, LiYF4, Li2TiF6, Li3YBr6, Li3LaBr6, Li3InBr6, LiInI4, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or lithium bis(fluorosulfonyl)imide (LiFSI). Optionally, the solid electrolyte may include one or more of LiZrCl5, Li3ZrCl7, LiAlCl4, Li3YBr6, lithium bis(trifluoromethanesulfonyl)imide or lithium bis(fluorosulfonyl)imide.

[0129] The above solid electrolyte has high ionic conductivity, thereby while intercepting the dissolution of manganese ions, it can effectively improve lithium ion conduction, so that the rate performance will not deteriorate due to the electrochemically inert phase layered lithium manganese oxide.

[0130] In some embodiments, a compound with the chemical formula A x B y C m can be obtained by ball-milling and mixing a first precursor compound including element A and element C and a second precursor compound including element B and element C in a stoichiometric ratio. The above steps are easy to operate, simple and feasible, and convenient for obtaining the required compound. For the ball-milling equipment, a jet mill, a planetary ball mill, a constant pressure ball mill, etc. can be cited, but not limited thereto. Here, a method for obtaining a compound with the chemical formula A x B y C m is exemplified. Those skilled in the art can select other methods to obtain the compound according to needs, not limited to the above steps.

[0131] In some embodiments, in terms of the molar amount of lithium element, the ratio of the addition amount of the second lithium source to the first lithium source is represented as ω, where 0 < ω < 0.2; optionally 0.0005 ≤ ω ≤ 0.1; optionally 0.005 ≤ ω ≤ 0.1. For example, ω can be 0.0005, 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1.

[0132] The ratio of the addition amount of the second lithium source to the first lithium source is related to the proportion of the layered lithium manganese oxide Li c Mn d O e in the matrix relative to the spinel lithium manganese oxide. As the ratio of the addition amount of the second lithium source to the first lithium source increases, the layered lithium manganese oxide Li c Mn d O eThe proportion relative to the spinel lithium manganese oxide increases. By controlling ω within the above range, it is beneficial to form an appropriate amount of layered lithium manganese oxide Li distributed on the surface layer of the spinel lithium manganese oxide. c Mn d O e 。

[0133] In some embodiments, the chemical formula of the matrix includes Li a Mn 2-b M b O 4-z X z , where 1 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.5, 0 ≤ z ≤ 0.1. M includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Li, Ti, and W. Optionally, M includes at least one of V, Tc, Ni, Al, Nb, Mo, Ti, and Zr. Optionally, M includes Al. X includes at least one of S, F, and Cl. Optionally, X includes at least one of F and Cl.

[0134] In some embodiments, the chemical formula of the matrix includes Li a Mn 2-b M b O 4-z X z , where 1 ≤ a ≤ 1.2, 0 < b ≤ 0.3, 0 ≤ z ≤ 0.1; M includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Ti, Li, and W; X includes at least one of S, F, and Cl.

[0135] In some embodiments, in the step of coating the matrix with the coating material, the mass of the coating material is 0.1% - 5% of the mass of the matrix, optionally 0.5% - 5%. For example, it can be 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, or 5%.

[0136] In some embodiments, the temperature of the first sintering can be 600°C - 800°C. For example, it can be 600°C, 650°C, 700°C, 750°C, or 800°C, but not limited thereto.

[0137] In some embodiments, the time of the first sintering can be 8h - 20h. For example, it can be 8h, 10h, 12h, 14h, 16h, 18h, or 20h, etc., but not limited thereto.

[0138] In some embodiments, the temperature of the second sintering may be 450°C to 800°C. For example, it may be 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, but is not limited thereto.

[0139] In some embodiments, the time of the second sintering may be 4h to 12h. For example, it may be 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, or 12h, etc., but is not limited thereto.

[0140] In some embodiments, the first sintering and / or the second sintering may be carried out in an air atmosphere, but is not limited thereto.

[0141] In addition, the battery and the electrical device of the present application will be described below with appropriate reference to the accompanying drawings.

[0142] Battery

[0143] In one embodiment of the present application, a battery is provided. The battery includes the positive electrode material described above or the positive electrode material prepared by the preparation method described above.

[0144] The term "battery" mentioned herein refers to a battery cell, a battery module, or a battery pack. Descriptions will be given separately below.

[0145] Generally, a battery cell includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charging and discharging process of the battery, active ions are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. The separator is disposed between the positive electrode plate and the negative electrode plate, mainly to prevent short circuit between the positive and negative electrodes, and at the same time allows ions to pass through.

[0146] [Positive Electrode Plate]

[0147] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes the positive electrode material of the first aspect of the present application.

[0148] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0149] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0150] In some embodiments, the positive electrode material may further include other positive electrode materials known in the art for lithium-ion batteries. As an example, the other positive electrode materials may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds, but the present application is not limited to these materials. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and their modified compounds, etc. At least one of the examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0151] During the charge and discharge process of the battery, the insertion and extraction and consumption of Li will occur, and the molar content of Li is different when the battery is discharged to different states. In the description of the positive electrode material in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. When the positive electrode material is applied to the battery system, the molar content of Li will change after charge and discharge cycles.

[0152] In the description of the positive electrode material in this application, the molar content of O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0153] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0154] In some embodiments, the positive electrode film layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0155] In some embodiments, the positive electrode plate can be prepared in the following manner: Disperse the components for preparing the positive electrode plate, such as the positive electrode active material, conductive agent, binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coat the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0156] [Negative electrode plate]

[0157] The negative electrode plate 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 the negative electrode film layer includes a negative electrode active material.

[0158] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0159] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0160] In some embodiments, the negative electrode active material may be a negative electrode active material for batteries well-known in the art. By way of example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials may include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, or silicon alloys. The tin-based materials may include at least one of elemental tin, tin oxides, or tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0161] In some embodiments, the negative electrode film layer may optionally further include a binder. The binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), or carboxymethyl chitosan (CMCS).

[0162] In some embodiments, the negative electrode film layer may optionally further include a conductive agent. The conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0163] In some embodiments, the negative electrode film layer may optionally further include other additives, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0164] In some embodiments, the negative electrode plate may be prepared by the following method: dispersing the components for preparing the negative electrode plate, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0165] [Electrolyte]

[0166] The electrolyte functions to conduct ions between the positive electrode plate and the negative electrode plate. There are no specific restrictions on the type of electrolyte in this application, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or all-solid-state.

[0167] In some embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0168] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, or lithium tetrafluoro(oxalato)phosphate.

[0169] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, or diethyl sulfone.

[0170] In some embodiments, the electrolytic solution may also optionally include additives. For example, the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives that can improve certain battery performance, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0171] [Separator film]

[0172] In some embodiments, the battery cell further includes a separator film. There are no special restrictions on the type of separator film in this application, and any well-known porous structure separator film with good chemical stability and mechanical stability can be selected.

[0173] In some embodiments, the material of the separator film may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, without special restrictions. When the separator film is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions.

[0174] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator film can be made into an electrode assembly by a winding process or a stacking process.

[0175] In some embodiments, the battery cell may include an outer package. The outer package can be used to encapsulate the above electrode assembly and electrolyte.

[0176] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic. As plastics, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed, etc.

[0177] This application does not particularly limit the shape of the battery cell, which can be cylindrical, square, or any other arbitrary shape. For example, Figure 5 is a battery cell 5 with a square structure as an example.

[0178] In some embodiments, referring to Figure 6 , the outer package can include a housing 51 and a top cover assembly 53. Among them, the housing 51 can include a bottom plate and side plates connected to the bottom plate. The bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0179] In some embodiments, the battery cells can be assembled into a battery module. The number of battery cells included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0180] Figure 7 is a battery module 4 as an example. Referring to Figure 7 , in the battery module 4, multiple battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Further, the multiple battery cells 5 can be fixed by fasteners.

[0181] Optionally, the battery module 4 can further include a housing with a receiving space, and multiple battery cells 5 are accommodated in the receiving space.

[0182] In some embodiments, the above battery module can also be assembled into a battery pack. The number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0183] Figure 8 and Figure 9 is a battery pack 1 as an example. Referring to Figure 8 and Figure 9, a battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0184] In addition, the present application also provides an electrical device, and the electrical device includes the battery provided by the present application. The battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0185] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0186] Figure 10 is an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the battery, a battery pack or a battery module can be used.

[0187] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thinness and lightness, and a battery cell can be used as the power source.

[0188] Embodiment

[0189] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific techniques or conditions, the techniques or conditions described in the literature in the art or according to the product specifications are followed. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial procurement.

[0190] Embodiment 1

[0191] (1) Preparation of the positive electrode material - Li 1.15 Mn 1.9 Al 0.1 O4@LiZrCl5

[0192] 1) Select lithium carbonate, electrolytic manganese dioxide, and aluminum oxide, weigh them according to the molar ratio of lithium element in lithium carbonate, manganese element in electrolytic manganese dioxide, and aluminum element in aluminum oxide of 1.1:1.9:0.1, ball mill for 4 h in a high-energy ball mill, and mix evenly; after drying, sinter at 750 °C for 16 h in an air atmosphere to obtain spinel lithium manganate (Li 1.1 Mn 1.9 Al 0.1 O4).

[0193] 2) Weigh lithium carbonate raw material with 5% of the molar amount of lithium element added in step 1), mix it with the spinel lithium manganate doped at the manganese site obtained in step 1), and sinter at 700 °C for 10 h in an air atmosphere to obtain the matrix (Li 1.15 Mn 1.9 Al 0.1 O4).

[0194] 3) Weigh LiCl and ZrCl4 according to the stoichiometric ratio (molar ratio) of 1:1 under dry conditions and mix them by high-energy ball milling to obtain the coating material LiZrCl5.

[0195] 4) Weigh and mix the matrix of the positive electrode material obtained in step 2) and the coating material obtained in step 3) according to a mass ratio of 1:0.03, and perform dry solid-phase ball milling coating, and then heat-treat at 400 °C to obtain a positive electrode material with high stability.

[0196] Figure 1 The scanning electron microscope image (SEM image) of the positive electrode material prepared in Example 1 is shown. Figure 2 The cross-sectional scanning electron microscope image and the element distribution table of the positive electrode material prepared in Example 1 are shown. Figure 3 The X-ray diffraction pattern (XRD pattern) of the positive electrode material prepared in Example 1 is shown. From Figure 1 it can be seen that the positive electrode material prepared in Example 1 has a large-grained polycrystalline morphology. From Figure 2 it can be seen that Zr and Cl elements from the coating layer are distributed on the surface of the matrix particles. From Figure 3As can be seen, in the XRD pattern of the positive electrode material prepared in Example 1, there are a first diffraction peak and a third diffraction peak with a 2θ diffraction angle between 20° and 23°, corresponding to the (020) and (-111) crystal planes of layered lithium manganese oxide Li2MnO3 (JCPDS No. 27-1252), belonging to the C / 2m space group. Moreover, there is also a strongest diffraction peak with a 2θ diffraction angle between 16° and 20°, which is the second diffraction peak and corresponds to the (111) crystal plane of spinel lithium manganate. The data were processed using the peak area integration function built into the XRD test software Jade to obtain the areas of the first, second, and third diffraction peaks respectively, so that the ratio of the sum of the peak areas of the first and third diffraction peaks to the peak area of the second diffraction peak can be calculated to be 0.079.

[0197] (2) Lithium-ion battery preparation

[0198] 1) Positive electrode sheet

[0199] According to the mass ratio of positive electrode material, conductive agent super-P, carbon nanotubes (CNT), and polyvinylidene fluoride (PVDF) of 95:1.5:0.5:3, after fully stirring and mixing evenly in N-methylpyrrolidone (NMP), a positive electrode slurry was prepared, and then the positive electrode slurry was coated on a 13-μm Al foil. After vacuum drying at 120°C, cold pressing, and slitting, a positive electrode sheet was obtained.

[0200] 2) Negative electrode sheet

[0201] The active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were fully stirred and mixed evenly in a deionized water solvent system according to the mass ratio of 95:2:2:1, and then coated on a Cu foil, dried, and cold pressed to obtain a negative electrode sheet.

[0202] 3) Electrolyte

[0203] In a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) with a mass ratio of 35:65, lithium salt LiPF6 was added and mixed evenly to obtain an electrolyte. Among them, the molar concentration of LiPF6 in the electrolyte is 1 mol / L.

[0204] 4) Separator

[0205] The separator is a 12-μm thick polyethylene porous membrane.

[0206] 5) Lithium-ion battery

[0207] Stack the positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator in the middle of the positive and negative electrodes to play an insulating role, and wind them to obtain a bare battery cell. Place the bare battery cell in an outer package, inject the prepared electrolyte and seal it, and obtain a lithium-ion battery through processes such as formation and degassing.

[0208] (3) Physical property testing of the positive electrode powder

[0209] 1) X-ray diffraction testing

[0210] Perform X-ray diffraction on the positive electrode material using a Bruker D8 DISCOVER X-ray diffractometer. The measurement conditions are as follows: Cu target, tube voltage of 40V, tube current of 40mA, scanning speed of 2° / min, 2θ scanning range of 15° to 85°, step size of 0.02°, emission slit (DS) of 1mm, anti-scattering slit (SS) of 8mm, and graphite monochromator.

[0211] (4) Electrochemical property testing

[0212] 1) Specific capacity testing

[0213] Using the positive electrode sheet prepared above as the positive electrode and a lithium sheet as the negative electrode, assemble a coin cell. Measure its discharge specific capacity at 0.1C from 3.0V to 4.35V and the charge-discharge curves from 3.0V to 4.8V. Specifically:

[0214] Charge at 0.1C to 4.35V, then perform constant voltage charging at 4.35V until the current ≤ 0.05mA, let it stand for 2 minutes, and then discharge at 0.1C to 3.0V. The discharge specific capacity at this time is the initial discharge specific capacity, denoted as D0.

[0215] Charge at 0.1C to 4.8V, then perform constant voltage charging at 4.8V until the current ≤ 0.05mA, record the charge curve, let it stand for 2 minutes, and then discharge at 0.1C to 3.0V and record the discharge curve.

[0216] The charge-discharge curves of the positive electrode material of Example 1 from 3.0V to 4.8V are shown in Figure 4 in. It can be seen from Figure 4 that above 4.5V, a charging platform that does not belong to spinel lithium manganate can be clearly observed on the charging platform, which corresponds to the activation of the layered lithium manganese oxide Li2MnO3 phase. This indicates that an inert phase Li2MnO3 is distributed on the surface layer of spinel lithium manganate.

[0217] 2) Cycle performance testing

[0218] At 25°C, perform charge-discharge cycle testing on the lithium-ion battery at a current density of 0.33C, and set the voltage range to 3.0V to 4.3V.

[0219] The lithium-ion battery was charged at a constant current of 0.33C to 4.3V in a constant-temperature environment of 25°C, then charged at a constant voltage of 4.3V until the current dropped to 0.05C, and then discharged at a constant current of 0.33C to 3.0V to obtain the first-cycle discharge capacity (C0). This charge-discharge process was repeated until the 800th cycle, and the discharge capacity after 800 cycles was obtained and denoted as C. n 。

[0220] Capacity retention rate = Discharge capacity after 800 cycles (C n ) / First-cycle discharge capacity (C0).

[0221] 3) Rate performance test

[0222] The lithium-ion battery was charged at a constant current of 0.5C to 4.3V at 25°C, further charged at a constant voltage of 4.3V until the current reached 0.05C, and then discharged to 3.0V at different discharge rates (1.0C, 4.0C) respectively.

[0223] 4) Test for manganese content in the negative electrode sheet after 800 cycles

[0224] The above lithium-ion battery after 800 cycles was disassembled to obtain the negative electrode sheet. Then, the negative electrode material on the copper foil of the negative electrode sheet was scraped off, dissolved in a mixed solvent (for example, 10 mL of aqua regia (a mixture of nitric acid and hydrochloric acid in a volume ratio of 1:1) was used for 0.4 g of negative electrode material), made up to 100 mL, and then the content of manganese element in the solution (g / mL) was measured using an ICP analyzer. The manganese element content in the negative electrode sheet = Content of manganese element in the solution × 100 mL ÷ Mass of negative electrode material used, unit: ppm.

[0225] Examples 2 to 4

[0226] The positive electrode material was prepared in the same manner as in Example 1, except that in step 1), the molar ratios of lithium, manganese, and aluminum elements were 1.1:1.95:0.05, 1.1:1.85:0.15, and 1.1:1.7:0.3 respectively.

[0227] Examples 5 to 8

[0228] The positive electrode material was prepared in the same manner as in Example 1, except that in step 1), the manganese-site doping element M added was changed from Al element in Example 1 to Ni, Nb, Ti, and Zr respectively. These elements were obtained using NiO, Nb2O5, TiO2, and ZrO2 as starting materials respectively.

[0229] Examples 9 to 12

[0230] The positive electrode material was prepared in the same manner as in Example 1, except that in step 2), the content of lithium element added was changed to 0.5%, 1%, 2%, and 10% respectively from 5% of the molar amount of lithium element added in step 1) in Example 1.

[0231] Example 13

[0232] The positive electrode material was prepared in the same manner as in Example 1, except that in step 3), the stoichiometric ratio of LiCl to ZrCl4 added was changed from 1:1 in Example 1 to 3:1.

[0233] Example 14

[0234] The positive electrode material was prepared in the same manner as in Example 1, except that in step 3), the added B element was changed from Zr in Example 1 to Al; the stoichiometric ratio of LiCl to AlCl3 in Example 14 was 1:1. The chemical formula of the synthesized solid electrolyte is LiAlCl4.

[0235] Example 15

[0236] The positive electrode material was prepared in the same manner as in Example 1, except that in step 3), the added B element was changed from Zr in Example 1 to Y; the C element was changed from Cl in Example 1 to Br; the stoichiometric ratio of LiBr to YBr3 in Example 15 was 3:1. The chemical formula of the synthesized solid electrolyte is Li3YBr6.

[0237] Example 16

[0238] The positive electrode material was prepared in the same manner as in Example 1, except that in step 3), commercially available lithium bis(fluorosulfonyl)imide salt LiFSI was directly used as the coating material.

[0239] Examples 17 - 19

[0240] The positive electrode material was prepared in the same manner as in Example 1, except that in step 4), the mass ratio of the coating material obtained in step 3) to the substrate obtained in step 2) was changed to 0.5%, 1%, and 5% respectively from 3% in Example 1.

[0241] Comparative Example 1

[0242] The difference between Comparative Example 1 and Example 1 is that step 2) is not carried out.

[0243] Comparative Example 2

[0244] The difference between Comparative Example 2 and Example 1 is that steps 3) and 4) are not carried out.

[0245] Table 1

[0246]

[0247]

[0248] In Table 1, "the molar ratio of the second lithium source to the first lithium source" represents the ratio of the amount of the lithium source added in step 2) to the amount of the lithium source added in step 1) in terms of the molar amount of lithium element; the "content (wt%)" of the coating material represents the percentage of the mass of the coating material relative to the mass of the matrix; "yes" indicates the presence of the corresponding diffraction peak; "no" indicates the absence of the corresponding diffraction peak.

[0249] Table 2

[0250]

[0251]

[0252] In Table 2, "discharge capacity 4C / 1C" represents the ratio of the discharge capacities of the battery at discharge rates of 4C and 1C.

[0253] It can be seen from Example 1 and Comparative Example 1 that by adding lithium element in step 2), the manganese content in the negative electrode sheet after 800 cycles is significantly reduced, from 698 ppm in Comparative Example 1 to 320 ppm in Example 1; the capacity retention rate during room temperature cycling for 800 cycles is improved, from 82.7% in Comparative Example 1 to 96.3% in Example 1; the rate performance of the material is slightly improved while basically remaining the same, being 96.9% in Comparative Example 1 and 97.1% in Example 1. This reflects that the layered lithium manganese oxide distributed on the surface of spinel lithium manganate can inhibit the dissolution of manganese ions, thereby improving the cycling performance.

[0254] It can be seen from Example 1 to Example 4 that by doping different contents of manganese-site doping elements in the matrix of the positive electrode material, the manganese content in the negative electrode sheet after cycling is relatively low, indicating that the doping of element M occupying the manganese site can effectively stabilize the material structure and inhibit the generation of Mn 2+ from the source, reduce the manganese dissolution, and improve the cycling performance of the material.

[0255] It can be seen from Example 1 and Example 5 to Example 8 that different manganese-site doping elements Al, Ni, Nb, Ti, and Zr can all effectively stabilize the material structure, inhibit the generation of Mn 2+ from the source, reduce the manganese dissolution, and improve the cycling performance of the material.

[0256] It can be seen from Examples 1 and 9 to 12 that with the increase of lithium added in step 2), the ratio of the diffraction peak between 20° and 23° to the strongest diffraction peak area between 16° and 20° gradually increases, the manganese content of the negative electrode sheet gradually decreases after cycling, and the corresponding capacity retention rate of 800 cycles at room temperature gradually increases. This reflects that the layered lithium manganese oxide phase in the positive electrode material can inhibit the dissolution of manganese ions in the material and improve the cycling performance of the material.

[0257] It can be seen from Example 1, Examples 13 to 19 and Comparative Example 2 that, compared with Comparative Example 2, Examples 1 and 13 to 19 have a solid electrolyte coating layer coated on the substrate surface, which can effectively inhibit the dissolution of manganese through the surface of the positive electrode material, improve the cycle performance of the material, and also improve the rate performance of the material.

[0258] It can be seen from Example 1, Examples 17 to 19 and Comparative Example 2 that as the amount of solid electrolyte coating layer added increases, the rate performance of the material gradually improves, the manganese content of the negative electrode sheet gradually decreases after cycling, and the corresponding capacity retention rate of 800 cycles at room temperature gradually increases. This reflects that the solid electrolyte coating can effectively inhibit manganese dissolution and improve the rate performance of the material.

[0259] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A cathode material, characterized in that, It includes a matrix and a coating layer. The coating layer covers at least a part of the surface of the matrix. The matrix includes spinel lithium manganese oxide and layered lithium manganese oxide distributed on the surface layer of the spinel lithium manganese oxide. The chemical formula of the layered lithium manganese oxide includes Li c Mn d O e , where 1 ≤ c ≤ 3, c / d > 0.5, 3 ≤ (2e - c) / d ≤ 4, and the coating layer includes a solid electrolyte.

2. The cathode material according to claim 1, characterized in that, In the X-ray diffraction pattern of the positive electrode material, there are a first diffraction peak of a layered lithium manganese oxide (020) plane with a 2θ diffraction angle between 20° and 23° and a second diffraction peak of a spinel lithium manganese oxide (111) plane with a 2θ diffraction angle between 16° and 20°.

3. The cathode material according to claim 2, characterized in that, The ratio of the peak area of the first diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.

2.

4. The cathode material according to claim 2, characterized in that, The ratio of the peak area of the first diffraction peak to the peak area of the second diffraction peak is 0.01 to 0.

14.

5. The cathode material according to claim 1, wherein In the X-ray diffraction pattern of the positive electrode material, there are a first diffraction peak of a layered lithium manganese oxide (020) plane with a 2θ diffraction angle between 20° and 23°, a third diffraction peak of a layered lithium manganese oxide (-111) plane with a 2θ diffraction angle between 20° and 23°, and a second diffraction peak of a spinel lithium manganese oxide (111) plane with a 2θ diffraction angle between 16° and 20°.

6. The cathode material according to claim 5, wherein The ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak is 0.001 to 0.

2.

7. The cathode material according to claim 5, characterized in that, The ratio of the sum of the peak areas of the first diffraction peak and the third diffraction peak to the peak area of the second diffraction peak is 0.01 to 0.

14.

8. The cathode material according to any one of claims 1 to 7, characterized in that, The chemical formula of the layered lithium manganese oxide includes Li2MnO3.

9. The cathode material according to any one of claims 1 to 8, characterized in that, The chemical formula of the matrix includes Li a Mn 2-b M b O 4-z X z , where 1 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.5, 0 ≤ z ≤ 0.1; M includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Ti, Li, W; X includes at least one of S, F, Cl.

10. The cathode material according to any one of claims 1 to 9, characterized in that, The chemical formula of the matrix includes Li a Mn 2-b M b O 4-z X z , where 1 ≤ a ≤ 1.2, 0 < b ≤ 0.3, 0 ≤ z ≤ 0.1; M includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Ti, Li, W; X includes at least one of S, F, Cl.

11. The cathode material according to any one of claims 1 to 10, characterized in that, The solid electrolyte includes at least one of a compound with the chemical formula A x B y C m , an alkali metal bis(trifluoromethanesulfonyl)imide salt, or an alkali metal bis(fluorosulfonyl)imide salt; Among the compounds of x B y C m where 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8; A includes at least one of Li, Na, and K; B includes at least one of La, Ce, Zr, Ti, Bi, In, Al, Y, Er, and Nb; C includes at least one of F, Cl, Br, I, and S.

12. The cathode material according to any one of claims 1 to 11, characterized in that, The solid electrolyte includes one or more of a compound with the chemical formula Li x B y C m , lithium bis(trifluoromethanesulfonyl)imide salt, or lithium bis(fluorosulfonyl)imide salt; In the compound of Li x B y C m , 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8; B includes at least one of Zr, Al, In, Y, Ti, and La; C includes at least one of F, Cl, Br, and I.

13. A method for preparing a cathode material, characterized in that, Including: At least mixing a first lithium source and a manganese source to obtain a first mixed material, and performing a first sintering on the first mixed material to obtain a first sintered product; Mixing the obtained first sintered product with a second lithium source to obtain a second mixed material, and performing a second sintering on the second mixed material to obtain a matrix; Coating the matrix with a coating material to obtain a positive electrode material, wherein the coating material includes a solid electrolyte, Among them, the positive electrode material includes a matrix and a coating layer. The coating layer covers at least a part of the surface of the matrix. The matrix includes spinel lithium manganese oxide and layered lithium manganese oxide distributed on the surface layer of the spinel lithium manganese oxide. The chemical formula of the layered lithium manganese oxide includes Li c Mn d O e , where 1 ≤ c ≤ 3, c / d > 0.5, 3 ≤ (2e - c) / d ≤ 4, and the coating layer includes a solid electrolyte.

14. The preparation method according to claim 13, characterized in that, An M source and / or an X source are also mixed in the first mixed material and / or the second mixed material; The M element in the M source includes at least one of V, Tc, Co, Ni, Mg, Fe, Al, Zn, Ca, Zr, Y, Nb, Mo, Cr, Li, Ti, and W; The X element in the X source includes at least one of S, F, and Cl.

15. The preparation method according to claim 14, characterized in that, Mixing an M source and / or an X source in the first mixed material, and in terms of the molar amounts of lithium element, manganese element, M element, and X element, the mixing ratio of the first lithium source, manganese source, M source, and X source is 0.95 to 1.2:1.5 to 2:0 to 0.5:0 to 0.

1.

16. The preparation method according to claim 14, characterized in that, Mixing an M source and / or an X source in the first mixed material, and in terms of the molar amounts of lithium element, manganese element, M element, and X element, the mixing ratio of the first lithium source, manganese source, M source, and X source is 0.95 to 1.2:1.7 to 2:0.0001 to 0.3:0 to 0.

1.

17. The preparation method according to any one of claims 13 to 16, characterized in that, The coating material includes at least one of a compound with the chemical formula A x B y C m , an alkali metal bis(trifluoromethanesulfonyl)imide salt, or an alkali metal bis(fluorosulfonyl)imide salt; In the compound with the chemical formula A x B y C m , 1 ≤ x ≤ 4, 1 ≤ y ≤ 3, 1 ≤ m ≤ 8; A includes at least one of Li, Na, and K; B includes at least one of La, Ce, Zr, Ti, Bi, In, Al, Y, Er, and Nb; C includes at least one of F, Cl, Br, I, and S.

18. The preparation method according to any one of claims 13 to 17, characterized in that, In terms of the molar amount of lithium element, the ratio of the addition amount of the second lithium source to the addition amount of the first lithium source is ω, where 0 < ω < 0.

2.

19. The preparation method according to any one of claims 13 to 18, characterized in that, In terms of the molar amount of lithium element, the ratio of the addition amount of the second lithium source to the addition amount of the first lithium source is ω, where 0.0005 ≤ ω ≤ 0.

1.

20. The preparation method according to any one of claims 13 to 19, characterized in that, In the step of coating the matrix with a coating material, the mass of the coating material is 0.1% to 5% of the mass of the matrix.

21. The preparation method according to any one of claims 13 to 20, characterized in that, The method satisfies one or more of the following conditions: (1) The temperature of the first sintering is 600°C to 800°C; (2) The time of the first sintering is 8 h to 20 h; (3) The temperature of the second sintering is 450°C to 800°C; (4) The time of the second sintering is 4 h to 12 h.

22. A battery, characterized in that, including the positive electrode material according to any one of claims 1 to 12 or the positive electrode material prepared by the preparation method according to any one of claims 13 to 21.

23. An electrical device, characterized in that, including the battery according to claim 22.

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