Lithium-rich manganese-based positive electrode material and manufacturing method therefor, positive electrode sheet, lithium ion battery and electrical apparatus

Abstract

The present application relates to a lithium-rich manganese-based positive electrode material and a manufacturing method therefor, a positive electrode sheet, a lithium ion battery, and an electrical apparatus. The lithium-rich manganese-based positive electrode material comprises an inner core containing a lithium-rich manganese-based active material, the lithium-rich manganese-based active material containing an element S. The residual stress of the lithium-rich manganese-based positive electrode material is 0.2% -2.2%, the oxygen defect index of the lithium-rich manganese-based positive electrode material is >1.82, and the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.07-0.19. The positive electrode material has excellent kinetic performance, cycle performance and high-temperature storage performance.

Description

Lithium-rich manganese-based positive electrode material, preparation method thereof, positive electrode sheet, lithium ion battery and electric device

[0001] The present application claims priority to the Chinese patent application No. 202411073612.3, filed on August 6, 2024, and entitled "Lithium-rich manganese-based positive electrode material, preparation method thereof, positive electrode sheet, lithium ion battery and electric device", the content of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of lithium ion batteries, in particular to a lithium-rich manganese-based positive electrode material, a preparation method thereof, a positive electrode sheet, a lithium ion battery and an electric device. BACKGROUND

[0003] In recent years, with the increasingly wide application of lithium ion batteries, lithium ion batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the rapid expansion of the lithium ion battery market, issues such as range anxiety and vehicle safety have become the focus of attention, and there is an urgent need to develop high-energy-density lithium ion positive electrode materials. Lithium-rich manganese-based active materials have high specific capacity and energy density, and are considered to be one of the most promising next-generation high-performance positive electrode materials.

[0004] However, lithium-rich manganese-based active materials have poor kinetics, cycle performance and high-temperature storage performance during use, which limits their application. SUMMARY

[0005] The present application provides a lithium-rich manganese-based positive electrode material with excellent kinetics, cycle performance and high-temperature storage performance, a preparation method thereof, a positive electrode sheet, a lithium ion battery and an electric device.

[0006] To achieve the above-mentioned purpose, the first aspect of the present application provides a lithium-rich manganese-based positive electrode material, comprising an inner core containing a lithium-rich manganese-based active material, wherein the lithium-rich manganese-based active material contains element S;

[0007] The residual stress of the lithium-rich manganese-based positive electrode material is 0.2%-2.2%;

[0008] The oxygen defect index of the lithium-rich manganese-based positive electrode material is >1.82;

[0009] The Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.07-0.19.

[0010] Thus, in the present application, by regulating the residual stress of the lithium-rich manganese-based positive electrode material within a suitable range, the stress accumulation of the material during cycling and storage can be reduced, the side reaction between the material and the electrolyte caused by excessive stress and particle cracking during the release process can be reduced, thereby further improving the cycling performance and high-temperature storage performance of the material; by regulating the oxygen defect index of the lithium-rich manganese-based positive electrode material within a suitable range, the formation of oxygen dimers can be reduced, thereby reducing the change in material structure caused by oxygen release, and reducing the liquid-solid interface between the material and the electrolyte when the material is used in a lithium ion battery, thereby achieving the purpose of improving the performance of the material; when the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is within the above range, it indicates that there is a certain amount of disordered spinel with FD-3M structure on the surface of the material, and this structure has three-dimensional lithium ion diffusion channels, which can accelerate the insertion and extraction of lithium ions and improve the dynamics of the material.

[0011] In some embodiments of the present application, the residual stress of the lithium-rich manganese-based positive electrode material is 0.25%-2%.

[0012] In some embodiments of the present application, the residual stress of the lithium-rich manganese-based positive electrode material is 0.2%-1.8%.

[0013] In some embodiments of the present application, the residual stress of the lithium-rich manganese-based positive electrode material is 0.25%-1.98%.

[0014] In some embodiments of the present application, the oxygen defect index of the lithium-rich manganese-based positive electrode material is 1.85-2.75.

[0015] In some embodiments of the present application, the oxygen defect index of the lithium-rich manganese-based positive electrode material is 1.83-2.76.

[0016] In some embodiments of the present application, the oxygen defect index of the lithium-rich manganese-based positive electrode material is 2-2.8.

[0017] In some embodiments of the present application, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.075-0.15.

[0018] In some embodiments of the present application, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.075-0.18.

[0019] In some embodiments of the present application, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.077-0.182.

[0020] In some embodiments of the present application, the surface of the lithium-rich manganese-based active material contains oxygen site-substituted element S. Thus, by introducing oxygen site-substituted element S on the surface of the lithium-rich manganese-based active material, the active oxygen release can be reduced, the performance deterioration due to oxygen production can be alleviated, and the cycle performance and high-temperature storage performance of the material can be improved.

[0021] In some embodiments of the present application, the mass percentage of element S in the lithium-rich manganese-based positive electrode material is 410 ppm-980 ppm.

[0022] In some embodiments of the present application, the mass percentage of element S in the lithium-rich manganese-based positive electrode material is 413 ppm-981 ppm.

[0023] In some embodiments of the present application, the chemical formula of the lithium-rich manganese-based active material is Li[Li m Ni a Co b Mn c M d ]O 2-e Z e , m+a+b+c+d=1, m>0, a+b+c+d<1, 0<b≤0.1, 0≤e≤0.2, M element includes one or more elements of Te, Se, Mg, Nb, Cr, Ce, Fe, Ta, B, V, Ti, Sn, W and Mo, and Z element includes one or more elements of F, Cl and Br. Thus, the element S contained on the surface of the lithium manganese-based active material exists at least partially in the form of Mn-S bond and Ni-S bond.

[0024] In some embodiments of the present application, a≥0.1, c≥0.5, d≥0.

[0025] In some embodiments of the present application, the lithium-rich manganese-based positive electrode material further comprises a coating layer, and the coating layer is coated on at least part of the surface of the core. By providing the coating layer, the interface stability can be improved, thereby improving the cycle performance and high-temperature storage performance of the material.

[0026] In some embodiments of the present application, the coating layer contains Q element, and the Q element includes one or more of Zr and Al. Thus, it is conducive to forming a point-like coating layer covering the surface of the core, forming a dense passivation layer, and improving gas production.

[0027] In some embodiments of the present application, the mass percentage of the Q element in the lithium-rich manganese-based positive electrode material is 500 ppm-8000 ppm. Thus, while improving the cycle performance and high-temperature storage performance of the material, the capacity of the material can also be taken into account.

[0028] In some embodiments of the present application, the mass percentage of the Q element in the lithium-rich manganese-based positive electrode material is 3000 ppm-6000 ppm.

[0029] In some embodiments of the present application, the lithium-rich manganese-based positive electrode material has one or more of the following characteristics (1)-(4):

[0030] (1) the volume average particle size Dv50 of the lithium-rich manganese-based positive electrode material is 6.0 μm-10.0 μm;

[0031] (2) the volume distribution diameter moment SPAN of the lithium-rich manganese-based positive electrode material is 0.8-1.2;

[0032] (3) the specific surface area of the lithium-rich manganese-based positive electrode material is <2.3 g / cm 2 ;

[0033] (4) the coating layer is in the form of a dot coating on at least part of the surface of the inner core;

[0034] (5) the thickness of the coating layer is 200 nm-900 nm.

[0035] In some embodiments of the present application, the specific surface area of the lithium-rich manganese-based positive electrode material is 1.3 g / cm 2 -1.8 g / cm 2 .

[0036] The second aspect of the present application also provides a preparation method of a lithium-rich manganese-based positive electrode material, comprising the following steps:

[0037] mixing an inner core containing a lithium-rich manganese-based active material and an ammonium sulfide solution to perform liquid phase treatment, so that the lithium-rich manganese-based active material contains element S, to prepare the lithium-rich manganese-based positive electrode material;

[0038] the residual stress of the lithium-rich manganese-based positive electrode material is 0.2%-2.2%;

[0039] the oxygen defect index of the lithium-rich manganese-based positive electrode material is >1.82;

[0040] the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.7-1.9.

[0041] Therefore, by adopting the ammonium sulfide solution to perform liquid phase treatment on the core, the lithium-rich manganese-based active material can be pre-activated, Li2O in the Li2MnO3 phase is removed, and a spinel phase with three-dimensional lithium ion diffusion channels is formed in the subsequent sintering process, so that the material kinetics can be improved. During the ammonium sulfide solution treatment process, the surface of the lithium-rich manganese-based active material will undergo a certain degree of S-O exchange, which can reduce the release of active oxygen, reduce the performance deterioration caused by oxygen release, and improve the cycle performance and high-temperature storage performance of the material.

[0042] In some embodiments of the present application, the ratio between the mass of ammonium sulfide contained in the ammonium sulfide solution and the mass of the core is 3-7.5; which is conducive to further improving the liquid phase treatment effect on the core.

[0043] In some embodiments of the present application, the stirring rate of the liquid phase treatment is 600 r / min-1000 r / min, and the time is 10 min-60 min; thereby, it is conducive to further improving the liquid phase treatment effect on the core.

[0044] In some embodiments of the present application, the mass percentage concentration of the ammonium sulfide solution is 20wt%-30wt%.

[0045] In some embodiments of the present application, the preparation method further comprises: mixing the core after the liquid phase treatment with a coating agent to perform a first sintering treatment, so as to form a coating layer on at least part of the surface of the core. The surface of the lithium-rich manganese-based active material after the liquid phase treatment is relatively unstable, and the core is coated and treated, which can further improve the interface stability and improve the cycle performance and storage performance of the material.

[0046] In some embodiments of the present application, the coating agent comprises one or more of ZrF4 and AlF3. ZrF4 and AlF3 have a low melting point, and when they are used as coating materials for coating treatment, they can form point-like coating on the surface of the core to form a dense passivation layer, thereby being conducive to further improving the interface stability and improving the gas production.

[0047] In some embodiments of the present application, the mass of the coating agent accounts for 0.09wt%-2.48wt% of the mass of the core.

[0048] In some embodiments of the present application, the first sintering treatment comprises one or more of the following conditions:

[0049] (1) the sintering temperature of the first sintering treatment is 350°C-550°C;

[0050] (2) the sintering time of the first sintering treatment is 8h-10h;

[0051] (3) the temperature increasing rate of the first sintering treatment is 2℃ / min-5℃ / min;

[0052] (4) the sintering atmosphere of the first sintering treatment comprises air.

[0053] In some embodiments of the present application, the preparation method of the core comprises:

[0054] subjecting the mixture containing the hydroxide precursor and the lithium source to a second sintering treatment; wherein the hydroxide precursor contains element Mn.

[0055] In some embodiments of the present application, the preparation method of the core comprises one or more of the following conditions:

[0056] (1) the chemical formula of the hydroxide precursor is Ni x Co y Mn z (OH)2, wherein x≥0.3, y≤0.1, z≥0.5;

[0057] (2) the ratio between the molar amount of lithium element contained in the lithium source and the total molar amount of metal elements contained in the hydroxide precursor is 1.3-1.4;

[0058] (3) the lithium source comprises one or more of lithium carbonate, lithium hydroxide monohydrate, lithium sulfate and lithium hydroxide;

[0059] (4) the sintering temperature of the second sintering treatment is 780℃-900℃;

[0060] (5) the sintering time of the second sintering treatment is 10h-15h;

[0061] (6) the temperature increasing rate of the second sintering treatment is 2℃ / min-5℃ / min;

[0062] (7) the sintering atmosphere of the second sintering treatment comprises air.

[0063] The third aspect of the present application provides a positive electrode tab comprising the lithium-rich manganese-based positive electrode material of the first aspect of the present application or prepared by the preparation method of the second aspect of the present application.

[0064] In some embodiments of the present application, the compaction density of the positive electrode tab is 2.7g / cm 3 -3.1g / cm 3 .

[0065] The fourth aspect of the present application provides a lithium ion battery comprising the positive electrode tab of the third aspect of the present application.

[0066] In some embodiments of the present application, the lithium ion battery comprises a lithium-rich manganese-based positive electrode material, the residual stress of the lithium-rich manganese-based positive electrode material is 3.5%-5%; the oxygen defect index of the lithium-rich manganese-based positive electrode material is greater than 0 and less than 1.5; and the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is greater than 0 and less than 0.04.

[0067] The lithium ion battery of the present application comprises the lithium-rich manganese-based positive electrode material provided by the present application, and has excellent kinetics, high initial efficiency and capacity, and excellent cycle performance and high-temperature storage performance.

[0068] The fifth aspect of the present application provides a power-using device comprising at least one of the positive electrode sheet of the third aspect of the present application and the lithium ion battery of the fourth aspect of the present application.

[0069] The power-using device of the present application comprises the lithium ion battery provided by the present application, and thus has at least the same advantages as the lithium ion battery.

[0070] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0071] For better describing and illustrating the embodiments or examples provided by the present application, one or more drawings can be referred to. Additional details or examples used for describing the drawings should not be considered as limiting the scope of any one of the disclosed applications, the presently described embodiments or examples, and the best mode presently understood of these applications. Moreover, the same reference numbers are used throughout the drawings to represent the same components. In the drawings:

[0072] FIG. 1 is an SEM image of the core, the core after liquid phase treatment, and the positive electrode material after coating in Example 1.

[0073] FIG. 2 is another SEM image of the positive electrode material prepared in Example 1.

[0074] FIG. 3 is a schematic view of a battery cell according to an embodiment of the present application.

[0075] FIG. 4 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG. 3.

[0076] FIG. 5 is a schematic view of a battery module according to an embodiment of the present application.

[0077] FIG. 6 is a schematic view of a battery pack according to an embodiment of the present application.

[0078] FIG. 7 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 6.

[0079] FIG. 8 is a schematic diagram of a power consuming device using a lithium ion battery as a power source according to an embodiment of the present application.

[0080] BRIEF DESCRIPTION OF DRAWINGS 1: battery pack; 2: upper case; 3: lower case; 4: battery module; 5: battery cell; 51: case; 52: electrode assembly; 53: cover plate; 6: power consuming device. DETAILED DESCRIPTION

[0081] Hereinafter, some embodiments of the lithium-rich manganese-based positive electrode material, the method for manufacturing the same, the positive electrode sheet, the lithium ion battery, and the power consuming device according to the present application are described in detail with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of matters known well, repeated descriptions of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0082] The "ranges" disclosed in the present application can be defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The ranges defined in this way can be inclusive or exclusive of the end values, either end value can be included or excluded independently, and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is also listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "j-k" represents a shorthand manner of describing the inclusion of any and all sub-ranges between the numbers "j" and "k", in which "j" and "k" are actual numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand manner of describing the inclusion of those numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to listing the parameter as, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like. For example, when it is stated that a parameter is an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0083] In the present application, "a plurality of", "a plurality of kinds", and the like, unless otherwise specified, refer to a number greater than 2 or equal to 2. For example, "one or more" means one or more than two.

[0084] If not particularly specified, all the embodiments and optional embodiments of the present application can be combined to form new technical solutions.

[0085] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment or implementation of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor does it necessarily exclude other embodiments or additional or alternative embodiments. It will be explicitly and implicitly appreciated by those skilled in the art that the embodiments described herein can be combined with other embodiments. Reference herein to "an implementation" has a similar understanding.

[0086] Those skilled in the art can understand that, in the method of each embodiment or embodiment, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. If not particularly specified, all the steps of the present application can be performed in sequence or randomly, preferably in sequence.

[0087] In the present application, the open technical features or technical solutions described with the words "containing", "including", "comprising" and the like do not exclude additional members other than the listed members, and can be regarded as providing both the closed features or solutions composed of the listed members and the open features or solutions including additional members other than the listed members. For example, A includes a1, a2 and a3, and unless otherwise specified, it can also include other members or can not include additional members, and can be regarded as providing the feature or solution that "A is composed of a1, a2 and a3", and also providing the feature or solution that "A includes a1, a2 and a3, and also includes other members". In the present application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0088] In the present application, "optionally", "optional" and "optional" mean that it can or can not be present, i.e. it can be selected from either of the two parallel solutions "yes" or "no". If there are multiple "optional" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "optional" is independent of each other.

[0089] The lithium-rich manganese-based active material has high specific capacity and energy density, and is considered as one of the most potential next-generation high-performance positive electrode materials. However, the lithium-rich manganese-based active material has poor overall kinetics due to the inert component Li2MnO3 in its structure; and active oxygen is inevitably produced when the lithium-rich manganese-based active material is charged to a high voltage, which aggravates the side reaction, resulting in poor cycle and high-temperature storage performance; in addition, oxygen is continuously produced during the cycle and storage process, and the generated oxygen will attack the additives (ester substances) in the electrolyte, aggravating the phase change of the material. Therefore, in some embodiments of the present application, the lithium-rich manganese-based active material is first treated by an ammonium sulfide solution in a liquid phase to improve the kinetics of the material, improve the initial efficiency and capacity of the material, and reduce oxygen release; and then combined with coating modification to improve the cycle performance and high-temperature storage performance of the material.

[0090] One or more embodiments of the present application provide a lithium-rich manganese-based positive electrode material, which includes an inner core containing a lithium-rich manganese-based active material, the lithium-rich manganese-based active material containing element S; the residual stress of the lithium-rich manganese-based positive electrode material is 0.2%-2.2%; the oxygen defect index of the lithium-rich manganese-based positive electrode material is >1.82; and the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.7-1.9.

[0091] As an example, the surface of the lithium-rich manganese-based active material can be determined for containing element S by an inductively coupled plasma spectrometer (ICP) according to EPA 6010D-2014.

[0092] Understandably, in the present application, by regulating the residual stress of the lithium-rich manganese-based positive electrode material within a suitable range, the stress accumulation of the material during the cycle and storage process can be reduced, and the side reaction between the material and the electrolyte caused by the excessive stress and particle cracking during the release process can be reduced, thereby further improving the cycle performance and high-temperature storage performance of the material; by regulating the oxygen defect index of the lithium-rich manganese-based positive electrode material within a suitable range, the formation of oxygen dimers can be reduced, thereby reducing the change in the structure of the material due to oxygen release, and reducing the deterioration of the liquid-solid interface between the material and the electrolyte when the material is used in a lithium ion battery, thereby achieving the purpose of improving the performance of the material; and when the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is within the above range, it indicates that there is a certain disordered spinel with FD-3M structure on the surface of the material, which has three-dimensional lithium ion diffusion channels, can accelerate the lithium ion intercalation and deintercalation, and improve the kinetics of the material.

[0093] By way of non-limiting example, the residual stress of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, or a range between any two of the foregoing residual stresses, etc.

[0094] By way of non-limiting example, the residual stress of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 0.25%-2.13%, 0.31%-1.98%, 0.43%-1.06%, 0.5%-1.98%, 0.65%-1.98%, 0.25%-0.93%, 0.25%-2%, 0.25%-1.98%, or 0.2%-1.8%, etc.

[0095] In some alternative embodiments, the residual stress of the lithium-rich manganese-based positive electrode material is 0.25%-2%.

[0096] In some alternative embodiments, the residual stress of the lithium-rich manganese-based positive electrode material is 0.25%-1.98%.

[0097] In some alternative embodiments, the residual stress of the lithium-rich manganese-based positive electrode material is 0.2%-1.8%.

[0098] It should be noted that the residual stress of the lithium-rich manganese-based positive electrode material mentioned above can be tested by X-ray diffraction method. Specifically, the following operations can be used:

[0099] Referring to the general XRD test rule JIS K 0131-1996, the dry sample with particle size <10 μm is subjected to X-ray diffraction test to obtain an X-ray diffraction spectrum. The residual stress of the lithium-rich manganese-based positive electrode material is calculated based on the formula: residual stress of the positive electrode material = (βhkl x Cosθhkl) / (4sinθhkl), wherein θhkl is the diffraction angle of the (hkl) crystal plane of the positive electrode material in the X-ray diffraction spectrum, and βhkl is the half-height width of the (hkl) crystal plane of the positive electrode material in the X-ray diffraction spectrum.

[0100] By way of example, the oxygen defect index of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 1.83, 1.85, 1.87, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, or a range between any two of the foregoing oxygen defect indices, etc.

[0101] As non-limiting examples, the oxygen deficiency index of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 1.83-2.71, 2.15-2.66, 2.26-2.58, 2.32-2.49, 2.15-2.76, 1.83-2.55, 1.85-2.75, 1.83-2.76, or 2-2.8, etc.

[0102] In some alternative embodiments, the oxygen deficiency index of the lithium-rich manganese-based positive electrode material is 1.85-2.75.

[0103] In some alternative embodiments, the oxygen deficiency index of the lithium-rich manganese-based positive electrode material is 1.83-2.76.

[0104] In some alternative embodiments, the oxygen deficiency index of the lithium-rich manganese-based positive electrode material is 2-2.8.

[0105] It should be noted that the above-mentioned oxygen deficiency index of the lithium-rich manganese-based positive electrode material can be tested by X-ray diffraction method. Specifically, the following operations can be used:

[0106] According to the general XRD test rule JIS K 0131-1996, the dry sample with a particle size of <10 μm is subjected to X-ray diffraction test to obtain an X-ray diffraction spectrum, and the X-ray diffraction spectrum refinement result is obtained by Rietveld method. Based on the X-ray diffraction spectrum refinement result and according to the formula: oxygen deficiency index = (d(I101) / d(I102)) 1 / 2 , I101 and I102 represent the (101) crystal face diffraction peak intensity value and the (102) crystal face diffraction peak intensity value of the positive electrode material in the X-ray diffraction spectrum, respectively, and the oxygen deficiency index of the lithium-rich manganese-based positive electrode material is calculated.

[0107] As examples, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.105, 0.11, 0.115, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, 0.17, 0.175, 0.18, 0.185, 0.19, or a range between any two of the above values, etc.

[0108] As non-limiting examples, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material can be, but is not limited to, 0.073-0.182, 0.077-0.182, 0.078-0.172, 0.083-0.162, 0.091-0.155, 0.12-0.155, 0.12-0.182, 0.14-0.182, 0.073-0.171, 0.075-0.15, or 0.075-0.18, etc.

[0109] In some alternative embodiments, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.075-0.15.

[0110] In some alternative embodiments, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.075-0.18. In some alternative embodiments, the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.077-0.182

[0111] It should be noted that the above-mentioned Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material can be tested by Fourier infrared spectroscopy. Specifically, the following operations can be used:

[0112] The Fourier infrared spectrum of the sample to be tested is obtained by Fourier infrared spectroscopy. The diffraction peak intensity at 730 cm -1 -750 cm -1 in the spectrum is the Ni-O peak intensity, and the diffraction peak intensity at 600 cm -1 -620 cm -1 in the spectrum is the Mn-O peak intensity, and then the Mn-O / Ni-O peak intensity ratio is calculated.

[0113] In some embodiments, the surface of the lithium-rich manganese-based active material contains oxygen site-substituted element S. Thus, by introducing oxygen site-substituted element S on the surface of the lithium-rich manganese-based active material, the release of active oxygen can be reduced, the performance deterioration caused by oxygen production can be alleviated, and the cycle performance and high-temperature storage performance of the material can be improved.

[0114] It should be noted that the "oxygen site substituted element S" refers to the element S replacing the element O on the surface of the lithium-rich manganese-based active material, S-O exchange occurs, and the element S is located at the oxygen site on the surface of the lithium-rich manganese-based active material and forms a covalent bond with the metal element. In some embodiments, the mass fraction of element S in the lithium-rich manganese-based positive electrode material is 410 ppm-980 ppm; for example, it can be, but is not limited to, 410 ppm, 430 ppm, 450 ppm, 470 ppm, 490 ppm, 500 ppm, 520 ppm, 540 ppm, 560 ppm, 580 ppm, 600 ppm, 620 ppm, 640 ppm, 660 ppm, 680 ppm, 700 ppm, 720 ppm, 740 ppm, 760 ppm, 780 ppm, 800 ppm, 820 ppm, 840 ppm, 860 ppm, 880 ppm, 900 ppm, 920 ppm, 940 ppm, 960 ppm, 980 ppm, or a range between any two of the above mass fractions.

[0115] As a non-limiting example, the mass fraction of element S in the lithium-rich manganese-based positive electrode material can be, but is not limited to, 413 ppm-981 ppm, 496 ppm-884 ppm, 633 ppm-752 ppm, 680 ppm-710 ppm, 496 ppm-981 ppm, 633 ppm-981 ppm, 695 ppm-981 ppm, 710 ppm-981 ppm, or 752 ppm-981 ppm, etc.

[0116] In some optional embodiments, the mass fraction of element S in the lithium-rich manganese-based positive electrode material is 413 ppm-981 ppm.

[0117] In some embodiments, the chemical formula of the lithium-rich manganese-based active material is Li[Li m Ni a Co b Mn c M d ]O 2-e Z e , m+a+b+c+d=1, m>0, a+b+c+d<1, 0

[0118] In some optional embodiments, a≥0.1, c≥0.5, d≥0.

[0119] In some embodiments, the lithium-rich manganese-based positive electrode material further comprises a coating layer, the coating layer being coated on at least part of the surface of the inner core. By providing the coating layer, the interface stability can be improved, thereby improving the cycle performance and high-temperature storage performance of the material.

[0120] As one possible implementation, the coating layer comprises a Q element, the Q element comprising one or more of Zr and Al. In this way, it is beneficial to form a point-like coating layer covering the surface of the inner core, to form a dense passivation layer, and to improve gas production.

[0121] In some embodiments, the mass fraction of the Q element in the lithium-rich manganese-based positive electrode material is 500 ppm-8000 ppm; for example, it can be but is not limited to 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm, or a range between any two of the above mass fractions, etc. When the mass fraction of the Q element in the lithium-rich manganese-based positive electrode material is within the above range, the cycle performance and high-temperature storage performance of the material can be improved while the capacity of the material is taken into account.

[0122] In some optional embodiments, the mass fraction of the Q element in the lithium-rich manganese-based positive electrode material is 3000 ppm-6000 ppm.

[0123] It can be understood that the technical solutions of the present application do not exclude the further inclusion of other materials in the inner core and / or the coating layer, especially the further inclusion of other positive electrode active materials in the inner core and / or the further inclusion of other coating materials in the coating layer.

[0124] In some embodiments, the coating layer is directly coated on at least part of the surface of the lithium-rich manganese-based active material of the inner core. As an example, the elements contained in the above-mentioned coating layer and the mass fraction of the elements in the lithium-rich manganese-based positive electrode material can be determined by inductively coupled plasma spectrometer (ICP) in accordance with EPA 6010D-2014.

[0125] In some embodiments, the volume average particle size Dv50 of the lithium-rich manganese-based positive electrode material is 6.0 μm-10.0 μm; for example, it can be but is not limited to 6.0 μm, 6.2 μm, 6.4 μm, 6.6 μm, 6.8 μm, 7.0 μm, 7.2 μm, 7.4 μm, 7.6 μm, 7.8 μm, 8.0 μm, 8.2 μm, 8.4 μm, 8.6 μm, 8.8 μm, 9.0 μm, 9.2 μm, 9.4 μm, 9.6 μm, 9.8 μm, 10.0 μm, or a range between any two of the above average particle sizes, etc.

[0126] Dv50 refers to the particle size corresponding to 50% in the volume distribution. As an example, Dv50 can be conveniently determined by referring to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, using a laser particle size analyzer, for example, a Mastersizer 2000E laser particle size analyzer of Malvern Instruments Ltd., UK.

[0127] In some embodiments, the volume distribution diameter moment SPAN of the lithium-rich manganese-based positive electrode material is 0.8-1.2; for example, it can be but is not limited to 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, or a range between any two of the above values, etc.

[0128] It should be noted that the volume distribution diameter moment SPAN=(Dv90-Dv10) / Dv50. Wherein, Dv10 refers to the particle size corresponding to 10% in the volume distribution, Dv50 refers to the particle size corresponding to 50% in the volume distribution, and Dv90 refers to the particle size corresponding to 50% in the volume distribution; Dv10, Dv50 and Dv90 can be determined by referring to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, using a laser particle size analyzer, and then SPAN is calculated according to the formula (Dv90-Dv10) / Dv50.

[0129] In some embodiments, the specific surface area of the lithium-rich manganese-based positive electrode material is <2.3 g / cm 2 ; for example, it can be but is not limited to 2.25 g / cm 2 , 2.2 g / cm 2 , 2.1 g / cm 2 , 2.0 g / cm 2 , 1.9 g / cm 2 , 1.8 g / cm 2 , 1.7 g / cm 2 , 1.6 g / cm 2 , 1.5 g / cm 2 , 1.4 g / cm 2 , 1.3 g / cm 2 , 1.2 g / cm 2 , 1.0 g / cm 2 , or a range between any two of the above specific surface areas, etc. When the specific surface area of the positive electrode material is in the above range, the storage performance, cycle performance and capacity of the material can be improved.

[0130] In some alternative embodiments, the specific surface area of the lithium-rich manganese-based positive electrode material is 1.3 g / cm 2 -1.8 g / cm 2 .

[0131] As an example, the specific surface area of the above-mentioned lithium-rich manganese-based positive electrode material can be determined by referring to GB / T 19587-2004 gas adsorption BET method.

[0132] In some embodiments, the coating layer is in the form of dots coated on at least part of the surface of the core.

[0133] As a possible embodiment, the thickness of the coating layer is 200 nm-900 nm; for example, it can be, but is not limited to, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, or a range between any two of the above thicknesses, etc. When the thickness of the coating layer is within the above range, the storage performance, cycle performance and capacity of the material can be improved.

[0134] As an example, the thickness of the coating layer can be determined by transmission electron microscopy (TEM).

[0135] One or more embodiments of the present application also provide a preparation method of the lithium-rich manganese-based positive electrode material, comprising the following steps:

[0136] mixing the core containing the lithium-rich manganese-based active material and the ammonium sulfide solution for liquid phase treatment, so that the surface of the lithium-rich manganese-based active material contains element S, to prepare the lithium-rich manganese-based positive electrode material;

[0137] The residual stress of the lithium-rich manganese-based positive electrode material is 0.2%-2.2%, the oxygen defect index of the lithium-rich manganese-based positive electrode material is >1.82, and the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is 0.07-0.19.

[0138] Understandably, in the preparation method, the ammonium sulfide solution is used to perform liquid phase treatment on the core, which can pre-activate the lithium-rich manganese-based active material, remove Li2O in Li2MnO3 phase, and form spinel phase with three-dimensional lithium ion diffusion channels in the subsequent sintering process, thereby improving the material kinetics. During the ammonium sulfide solution treatment process, the surface of the lithium-rich manganese-based active material will undergo a certain degree of S-O exchange, which can reduce the release of active oxygen, reduce the performance deterioration caused by oxygen release, and improve the cycle performance and high-temperature storage performance of the material.

[0139] In some embodiments, the ratio between the mass of ammonium sulfide contained in the ammonium sulfide solution and the mass of the core is 3-7.5; for example, it can be, but is not limited to, 3, 3.3, 3.5, 3.7, 4, 4.3, 4.5, 4.7, 5, 5.3, 5.5, 5.7, 6, 6.3, 6.5, 6.7, 7, 7.3, 7.5, or a range between any two of the above values, etc. When the amount of the ammonium sulfide solution is within the above range, it is beneficial to further improve the liquid phase treatment effect on the core.

[0140] As a possible embodiment, the mass percentage concentration of the ammonium sulfide solution is 20wt%-30wt%. For example, it can be, but is not limited to, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, or a range between any two of the above mass percentage concentrations, etc. When the mass percentage concentration of the ammonium sulfide solution is within the above range, it is beneficial to further improve the liquid phase treatment effect on the core.

[0141] As a non-limiting example, the solvent of the ammonium sulfide solution can be water.

[0142] In some of the embodiments, the stirring rate of the liquid phase treatment is 600r / min-1000r / min; for example, it can be, but is not limited to, 600r / min, 650r / min, 700r / min, 750r / min, 800r / min, 850r / min, 900r / min, 950r / min, 1000r / min, or a range between any two of the above stirring rates, etc.

[0143] In some exemplary embodiments, the time of the liquid phase treatment is 10min-60min; for example, it can be, but is not limited to, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, or a range between any two of the above times, etc.

[0144] When the stirring rate and the time of the liquid phase treatment are within the above ranges, respectively, it is beneficial to further improve the liquid phase treatment effect on the core.

[0145] It should be noted that the stirring rate and the time of the liquid phase treatment can be combined in any suitable manner, and both can be selected from any of the stirring rates and times of the liquid phase treatment described herein.

[0146] In some embodiments, the method for preparing the lithium-rich manganese-based positive electrode material further comprises: mixing the inner core after the liquid phase treatment with a coating agent to perform a first sintering treatment, so as to form a coating layer on at least part of the surface of the inner core. The surface of the lithium-rich manganese-based active material after the liquid phase treatment is relatively unstable, and the coating treatment on the inner core can further improve the interface stability and improve the cycle performance and storage performance of the material.

[0147] In some embodiments, the coating agent comprises one or more of ZrF4 and AlF3. The melting point of ZrF4 and AlF3 is relatively low, and the coating treatment with the coating agent can form a point-shaped coating covering the surface of the inner core, forming a dense passivation layer, thereby facilitating further improvement of the interface stability and improvement of gas production.

[0148] As a possible embodiment, the mass of the coating agent accounts for 0.09wt%-2.48wt% of the mass of the inner core; for example, it can be but is not limited to 0.09wt%, 0.1wt%, 0.13wt%, 0.16wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2.0wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt%, 2.48wt%, or a range between any two of the above values, etc.

[0149] In some embodiments, the sintering temperature of the first sintering treatment is 350°C-550°C; for example, it can be but is not limited to 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, or a range between any two of the above temperatures, etc.

[0150] As a possible embodiment, the sintering time of the first sintering treatment is 8h-10h; for example, it can be but is not limited to 8h, 8.5h, 9h, 9.5h, 10h, or a range between any two of the above times, etc.

[0151] In some exemplary embodiments, the heating rate of the first sintering treatment is 2°C / min-5°C / min; for example, it can be but is not limited to 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, 5°C / min, or a range between any two of the above heating rates, etc.

[0152] It is to be understood that the sintering temperature, the sintering time and the heating rate of the first sintering process can be combined in any suitable manner, and each of them can be selected from any of the sintering temperature, the sintering time and the heating rate of the first sintering process described herein.

[0153] As a possible implementation, the sintering atmosphere of the first sintering process comprises air.

[0154] As a non-limiting example, the preparation method of the core comprises: subjecting the mixture comprising the hydroxide precursor and the lithium source to a second sintering process; wherein the hydroxide precursor contains the element Mn.

[0155] In some optional embodiments, the chemical formula of the hydroxide precursor is Ni x Co y Mn z (OH)2, wherein x≥0.3, y≤0.1, and z≥0.5.

[0156] In some exemplary embodiments, the ratio between the molar amount of lithium element contained in the lithium source and the total molar amount of metal elements contained in the hydroxide precursor is 1.3-1.4; for example, it can be but is not limited to 1.3, 1.32, 1.34, 1.36, 1.38, 1.4, or a range between any two of the above values, etc.

[0157] In some of the embodiments, the sintering temperature of the second sintering process is 780-900°C; for example, it can be but is not limited to 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, or a range between any two of the above sintering temperatures, etc.

[0158] As a possible implementation, the sintering time of the second sintering process is 10-15h; for example, it can be but is not limited to 10h, 11h, 12h, 13h, 14h, 15h, or a range between any two of the above times, etc.

[0159] In some optional embodiments, the heating rate of the second sintering process is 2-5°C / min; for example, it can be but is not limited to 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, 5°C / min, or a range between any two of the above heating rates, etc.

[0160] It is to be noted that the sintering temperature, the sintering time and the heating rate of the second sintering process can be combined in any suitable manner, and each of them can be selected from any of the sintering temperature, the sintering time and the heating rate of the second sintering process described herein.

[0161] In some alternative embodiments, the sintering atmosphere of the second sintering process comprises air.

[0162] In some embodiments, the lithium source comprises one or more of lithium carbonate, lithium hydroxide monohydrate, lithium sulfate and lithium hydroxide.

[0163] In addition, the lithium ion battery and the electric device of the present application are described below with appropriate reference to the accompanying drawings.

[0164] Generally, the lithium ion battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the charging and discharging of the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly playing a role of preventing the short circuit of the positive and negative electrodes, while allowing the ions to pass through.

[0165] Positive electrode sheet

[0166] The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises the lithium-rich manganese-based positive electrode material described above.

[0167] In some embodiments, the compaction density of the positive electrode sheet is 2.7 g / cm 3 - 3.1 g / cm 3 For example, it can be, but is not limited to, 2.7 g / cm 3 , 2.8 g / cm 3 , 2.9 g / cm 3 , 3.0 g / cm 3 , 3.1 g / cm 3 or a range between any two of the above values, etc.

[0168] In some embodiments, the lithium ion battery comprises the positive electrode sheet described above.

[0169] In some embodiments, the lithium ion battery comprises a lithium-rich manganese-based positive electrode material, wherein the residual stress of the lithium-rich manganese-based positive electrode material is 3.5%-5%; the oxygen defect index of the lithium-rich manganese-based positive electrode material is greater than 0 and less than 1.5; and the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is greater than 0 and less than 0.04.

[0170] The lithium ion battery of the present application comprises the lithium-rich manganese-based positive electrode material provided by the present application, and has excellent kinetics, high initial efficiency and capacity, and excellent cycle performance and high-temperature storage performance.

[0171] As a non-limiting example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode active material layer is provided on either one or both of the two opposite surfaces of the positive electrode current collector.

[0172] In some embodiments, the positive electrode current collector can adopt a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be adopted. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be obtained by forming a metal material on a polymer material base material. In the positive electrode current collector, non-limiting examples of the metal material can include one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, a silver alloy, and the like. In the positive electrode current collector, non-limiting examples of the polymer material base material can include one or more of a polypropylene (PP) base material, a polyethylene terephthalate (PET) base material, a polybutylene terephthalate (PBT) base material, a polystyrene (PS) base material, a polyethylene (PE) base material, and the like.

[0173] It can be understood that the battery will be accompanied by lithium (Li) deintercalation and consumption during charging and discharging, and the content of Li in the positive electrode sheet is different when the battery is discharged to different states. In the enumeration of the positive electrode material in the present application, the content of Li is the initial state of the material unless otherwise specified. When the positive electrode material is applied to the positive electrode sheet in the battery system, the content of Li in the positive electrode material contained in the sheet will usually change after charging and discharging cycles. The content of Li can be quantified by molar content, but is not limited thereto. As for "the content of Li is the initial state of the material", the initial state of the material refers to the state before being put into the positive electrode slurry. It can be understood that new materials obtained by proper modification on the basis of the enumerated positive electrode materials are also within the scope of the positive electrode materials, and the foregoing proper modification refers to acceptable modification methods for the positive electrode material, and non-limiting examples include coating modification.

[0174] In the enumeration of the positive electrode material in the present application, the content of oxygen (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 content of O will fluctuate. The content of O can be quantified by molar content, but is not limited thereto.

[0175] In some embodiments, the positive active material can also employ positive active materials for batteries known in the art. As non-limiting examples, the positive active material can include one or more of lithium-containing phosphates of olivine structure, lithium transition metal oxides, and modified compounds of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as positive active materials for batteries can also be used. These positive active materials can be used singly only or in combination of two or more. Among them, examples of the lithium transition metal oxide can include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds thereof. Non-limiting examples of the lithium-containing phosphates of olivine structure can include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon. Non-limiting examples of the lithium cobalt oxide can include LiCoO2; non-limiting examples of the lithium nickel oxide can include LiNiO2; non-limiting examples of the lithium manganese oxide can include LiMnO2, LiMn2O4, and the like; non-limiting examples of the lithium nickel cobalt manganese oxide can include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also referred to simply as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to simply as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to simply as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to simply as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to simply as NCM 811 ) and the like. Non-limiting examples of the lithium nickel cobalt aluminum oxide can include LiNi 0.80 Co 0.15 Al 0.05 O2.

[0176] In some embodiments, the positive electrode active material layer optionally further includes a binder. As non-limiting examples, the binder can include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0177] In some embodiments, the positive electrode active material layer optionally further includes a conductive agent. As non-limiting examples, the conductive agent can include one or more of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0178] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry on at least one side surface of the positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode tab can be obtained. The type of the solvent can be selected from, but is not limited to, any of the aforementioned embodiments, such as N-methyl pyrrolidone (NMP). The surface of the positive electrode current collector to which the positive electrode slurry is coated can be on a single surface of the positive electrode current collector, or on both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40 wt% to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 mPa s to 25000 mPa s. When coating the positive electrode slurry, the coating unit area density, in terms of dry weight (excluding the solvent), can be 15 mg / cm 2 - 35 mg / cm 2 . The compaction density of the positive electrode tab can be 2.7 g / cm 3 - 3.1 g / cm 3 .

[0179] Negative electrode tab

[0180] The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material.

[0181] As non-limiting examples, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active material layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0182] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be obtained by forming a metal material on a polymer material base layer. Non-limiting examples of the metal material in the negative current collector can include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, and the like. Non-limiting examples of the polymer material base layer in the negative current collector can include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and the like.

[0183] In some embodiments, the negative active material can employ a negative active material for a battery known in the art. As non-limiting examples, the negative active material can include one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, and the like. The silicon-based material can include one or more of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can include one or more of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. The negative active material can be used alone or in combination of two or more.

[0184] In some embodiments, the negative active material layer can further optionally include a binder. The binder can include one or more of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0185] In some embodiments, the negative active material layer can further optionally include a conductive agent. The conductive agent can include one or more of super P, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0186] In some embodiments, the negative active material layer can further optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

[0187] In some embodiments, the negative electrode sheet can be prepared by dispersing the components described above for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (a non-limiting example of the solvent is deionized water), to form a negative electrode slurry; coating the negative electrode slurry on at least one side surface of the negative electrode current collector; and drying, cold-pressing, or the like, to obtain the negative electrode sheet. The surface of the negative electrode current collector to which the negative electrode slurry is coated can be a single surface of the negative electrode current collector, or both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40 wt% to 60 wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 mPa·s to 10000 mPa·s. The coating unit area density of the negative electrode slurry, on a dry weight basis (excluding the solvent), can be 75 g / m 2 -220 g / m 2 . The compaction density of the negative electrode sheet can be 1.0 g / cm 3 -1.8 g / cm 3 .

[0188] Electrolyte

[0189] The electrolyte has a function of conducting ions between the positive electrode sheet and the negative electrode sheet. The type of the electrolyte is not particularly limited in the present application, and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0190] In some embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0191] In some embodiments, the electrolyte salt can include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluoro-oxalato-borate (LiDFOB), lithium bis-oxalato-borate (LiBOB), lithium difluoro-bis-oxalato-phosphate (LiDFOP), and lithium tetrafluoro-oxalato-phosphate (LiTFOP).

[0192] In some embodiments, the solvent can include ethylene carbonate (EC, ), propylene carbonate (PC, ), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), and the like.

[0193] In some embodiments, the electrolyte solution further optionally includes an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can further include an additive that can improve certain performance of the battery, such as an additive that improves overcharge performance of the battery, an additive that improves high-temperature or low-temperature performance of the battery, and the like.

[0194] In some embodiments, the additive in the electrolyte solution can include, but is not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), and the like.

[0195] Separator film

[0196] In some embodiments, the lithium ion battery further includes a separator film. The type of the separator film is not particularly limited in the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0197] In some embodiments, the material of the separator film can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0198] In some embodiments, the thickness of the separator film is 6-40 pm, and can be 13 pm.

[0199] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be used to make an electrode assembly through a winding process or a stacking process.

[0200] In some embodiments, the lithium ion battery can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte solution described above.

[0201] In some embodiments, the outer package of the lithium ion battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, and the like. The outer package of the lithium ion battery can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, and further, non-limiting examples of the plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate, and the like.

[0202] The lithium ion battery includes at least one battery cell. The lithium ion battery can include one or more battery cells.

[0203] In the present application, a "battery cell" refers to a basic unit capable of converting chemical energy and electrical energy to each other, and further, generally includes at least a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the charging and discharging of the battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct the active ions between the positive electrode sheet and the negative electrode sheet.

[0204] The shape of the battery cell is not particularly limited in the present application, and can be cylindrical, square, or any other shape. For example, FIG. 3 is a battery cell 5 of a square structure as an example.

[0205] In some embodiments, referring to FIG. 4, the outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and a side plate connected to the bottom plate, which enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be selected by a person skilled in the art according to actual needs.

[0206] The lithium ion battery can be a battery module 4 or a battery pack 1.

[0207] The battery module includes at least one battery cell. The number of battery cells contained in the battery module can be one or more, which can be selected by a person skilled in the art according to the application and capacity of the battery module.

[0208] FIG. 5 is a battery module 4 as an example. Referring to FIG. 5, in the battery module 4, a plurality of 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 manner. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0209] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0210] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, which can be selected by a person skilled in the art according to the application and capacity of the battery pack.

[0211] FIGS. 6 and 7 are a battery pack 1 as an example. Referring to FIGS. 6 and 7, a battery case and a plurality of battery modules 4 disposed in the battery case can be included in the battery pack 1. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 can be disposed on the lower case 3 to form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery case in any manner.

[0212] In addition, the application also provides a power utilization device, which comprises the lithium ion battery provided by the application. The lithium ion battery can be used as a power supply of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto. Among them, the mobile device can be a mobile phone, a notebook computer, etc.; the electric vehicle can be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited thereto.

[0213] As the power utilization device, the lithium ion battery can be selected according to the use requirements thereof.

[0214] FIG. 8 is a power utilization device 6 as an example. The power utilization 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 power utilization device for the lithium ion battery, a battery pack or a battery module can be used.

[0215] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thin and light, and the lithium ion battery can be used as a power supply.

[0216] Hereinafter, the embodiments of the application will be described. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application. If the technology or conditions are not specified in the embodiments, the technology or conditions described in the literature in the art or according to the product manual are used. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0217] I. Preparation Example 1 of the positive electrode material

[0218] Step S1, Ni 0.35 Co 0.04 Mn 0.65(OH)2 (hydroxide precursor), LiOH H2O (lithium salt), ball-milled zirconium beads, and the mixture was prepared by putting the ball-milled zirconium beads and the materials into a drum-type ball-milling mixer at a mass ratio of 35 of the ball-milled zirconium beads to the materials; wherein the molar ratio of Li / Me was 1.35, and Me was the total metal molar amount of nickel, cobalt, and manganese. The mixture was put into a muffle furnace for sintering treatment, the sintering temperature was 880°C, the heating rate was 4°C / min, the sintering time was 13 h, and the sintering atmosphere was air, to obtain the core.

[0219] In step S2, the ammonium sulfide solution with a mass percentage concentration of 26wt% was mixed and stirred with the core for liquid phase treatment; wherein the mass ratio of the dry weight of the ammonium sulfide solution to the mass of the core was 5.5, the stirring rate was 900 r / min, and the treatment time was 25 min. After the liquid phase treatment, suction filtration, deionized water washing, and suction filtration were performed, and then the core after the liquid phase treatment was obtained by drying at 80°C for 10 h, followed by mechanical grinding and vibration screening treatment.

[0220] In step S3, the core after the liquid phase treatment was put into a drum-type ball-milling mixer with the coating agent AlF3 for 8 h of mixing, and then put into a muffle furnace for sintering treatment; wherein the amount of the coating agent AlF3 was 1.25wt% of the mass of the core, the sintering temperature was 450°C, the heating rate was 3°C / min, the sintering time was 9.5 h, the sintering atmosphere was air, and the lithium-rich manganese-based positive electrode material was obtained after mechanical grinding and vibration screening treatment of the material after sintering.

[0221] Example 2-17

[0222] The preparation method of Example 2-17 was similar to that of Example 1, and the differences were shown in Table 1. In Example 17, only the liquid phase treatment of step S2 was performed on the core obtained in step S1, and the coating of step S3 was not performed.

[0223] Comparative Example 1

[0224] The preparation method of Comparative Example 1 was different from that of Example 1 in that the core obtained in step S1 was not subjected to liquid phase treatment and coating.

[0225] Comparative Example 2

[0226] The preparation method of Comparative Example 2 was different from that of Example 1 in that the core obtained in step S1 was not subjected to the liquid phase treatment of step S2, but was directly subjected to the coating of step S3.

[0227] Comparative Example 3

[0228] The preparation method of Comparative Example 3 was different from that of Example 8 in that the core obtained in step S1 was not subjected to the liquid phase treatment of step S2, but was directly subjected to the coating of step S3.

[0229] In the preparation process of the positive electrode material of Example 1, the core prepared in step S1, the core after liquid phase treatment in step S2, and the positive electrode material after coating in step S3 were observed by scanning electron microscopy, and the results are shown in FIG. 1. In FIG. 1, a is the SEM image of the core prepared in step S1; b is the SEM image of the core after liquid phase treatment in step S2; and c is the SEM image of the positive electrode material after coating in step S3. As can be seen from FIG. 1, after liquid phase treatment, some washing traces appear on the surface of the core, and after coating, the traces on the surface of the positive electrode material are significantly improved; which indicates that the surface of the lithium-rich manganese-based active material after liquid phase treatment is relatively unstable, and after coating with ZrF4 or AlF3 coating material with low melting point, the interface stability can be further improved.

[0230] Another SEM image of the lithium-rich manganese-based positive electrode material prepared in Example 1 is shown in FIG. 2. As can be seen from FIG. 2, the coating layer of the lithium-rich manganese-based positive electrode material is point-like coating.

[0231] The settings of each of the above examples and comparative examples are shown in Table 1.

[0232] Table 1

[0233] In Table 1, n1 represents the ratio between the dry weight of the ammonium sulfide solution and the mass of the core. n2 represents the amount of coating agent, which accounts for 100% of the mass of the core. T represents the sintering temperature of the sintering treatment in step S3.

[0234] The positive electrode materials prepared in each of the above examples and comparative examples were tested for the following parameters: residual stress, oxygen defect index, Mn-O / Ni-O peak intensity ratio, S element content, mass percentage of Al or Zr in the positive electrode material, volume average particle size Dv50 of the positive electrode material, volume distribution span SPAN of the positive electrode material, specific surface area of the positive electrode material, and coating layer thickness. The test methods are as follows:

[0235] Residual stress: The parameters were measured according to the general rules of XRD test JIS K 0131-1996, and the dry sample with particle size <10 μm was tested by X-ray diffraction to obtain the X-ray diffraction pattern. The residual stress of the positive electrode material was calculated based on the formula: residual stress of the positive electrode material = (βhkl x Cosθhkl) / (4sinθhkl), wherein θhkl is the diffraction angle of the (hkl) crystal plane of the positive electrode material in the X-ray diffraction pattern, and βhkl is the half-height width of the (hkl) crystal plane of the positive electrode material in the X-ray diffraction pattern.

[0236] Oxygen defect index: according to the general rules of XRD test JIS K 0131-1996, dry the sample to be tested with a particle size of <10 μm, and then perform X-ray diffraction test to obtain the X-ray diffraction pattern, and obtain the X-ray diffraction pattern refinement result by Rietveld method. Based on the X-ray diffraction pattern refinement result and according to the formula: oxygen defect index = (d(I101) / d(I102)) 1 / 2 , I101 and I102 represent the (101) crystal face diffraction peak intensity value and the (102) crystal face diffraction peak intensity value of the positive electrode material in the X-ray diffraction pattern, respectively, and the oxygen defect index of the lithium-rich manganese-based positive electrode material is calculated.

[0237] Mn-O / Ni-O peak intensity ratio: Fourier infrared spectrum test is performed on the sample to be tested to obtain a Fourier infrared spectrum, the diffraction peak intensity at 730 cm -1 -750 cm -1 in the spectrum is the Ni-O peak intensity, the diffraction peak intensity at 600 cm -1 -620 cm -1 in the spectrum is the Mn-O peak intensity, and then the Mn-O / Ni-O peak intensity ratio is calculated.

[0238] Elemental S content: inductively coupled plasma spectrometer (ICP) is used to determine according to EPA 6010D-2014.

[0239] Mass fraction of Al or Zr in the positive electrode material: inductively coupled plasma spectrometer (ICP) is used to determine according to EPA 6010D-2014.

[0240] Volume average particle size Dv50 of the positive electrode material and span of the volume distribution of the positive electrode material: GB / T 19077-2016 particle size distribution laser diffraction method is referred to, Mastersizer 2000E laser particle size analyzer of British Malvern Instruments Co., Ltd. is used to determine Dv10, Dv50 and Dv90, and then SPAN is calculated according to the formula (Dv90-Dv10) / Dv50.

[0241] Specific surface area of the positive electrode material: gas adsorption BET method is referred to in GB / T 19587-2004.

[0242] Coating layer thickness: transmission electron microscope (TEM) is used for determination.

[0243] The results are shown in Table 2.

[0244] Table 2

[0245] II. Preparation of batteries and performance test

[0246] 1) Preparation of positive electrode sheet

[0247] The positive electrode material prepared in Example 1 was put into a 5L stirring tank and pre-mixed for 30 minutes, then the conductive agent acetylene black (SP) and the binder polyvinylidene fluoride (PVDF) were added for secondary dry mixing for 30 minutes. Finally, the solvent N-methyl pyrrolidone (NMP) was added and rapid stirring was carried out under vacuum to form a slurry. The mass ratio of the positive electrode material: acetylene black: polyvinylidene fluoride was 96:2:2, and the solid content of the slurry was 70wt%. The slurry was uniformly coated on both sides of an aluminum foil with a thickness of 12μm, and the coated electrode sheet was taken out after drying in an oven at 100℃-130℃ for half an hour. The positive active material loading of the electrode sheet was 21.5mg / cm 2 .

[0248] 2) Preparation of negative electrode sheet

[0249] The negative active material artificial graphite, the conductive agent acetylene black, the binder styrene butadiene rubber (SBR), and the thickening agent sodium carboxymethyl cellulose (CMC) were mixed in a weight ratio of 90:5:2:2:1 in a deionized water solvent system, and then uniformly coated on a copper foil, dried, and cold-pressed to obtain a negative electrode sheet.

[0250] 3) Separator film

[0251] A 13μm thick polyethylene porous film was selected as the separator film.

[0252] 4) Preparation of electrolyte

[0253] The organic solvent was a mixture containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), wherein the volume ratio of EC, EMC, and DMC was 1:1:1. In an argon glove box with a water content of <10ppm, the fully dried lithium salt LiPF6 was dissolved in the organic solvent and mixed uniformly to obtain an electrolyte. The concentration of the lithium salt was 1mol / L.

[0254] 5) Preparation of battery

[0255] Preparation of lithium ion battery: The positive electrode sheet, the separator film, and the negative electrode sheet were stacked in order, with the separator film between the positive and negative electrode sheets to act as a separator, then the bare cell was wound into a square shape, and then was placed in an aluminum plastic film. After drying at 80℃ to remove water, 1.2g of the corresponding non-aqueous electrolyte was injected, sealed, and subjected to processes such as standing, hot and cold pressing, formation, clamping, and capacity distribution to obtain a lithium ion battery.

[0256] Preparation of button cell: In an argon-filled glove box, CR2032 button cells were assembled in the order of positive shell, positive electrode, separator, negative electrode, steel sheet, spring sheet and negative shell from top to bottom, and then rested for 6 hours for standby.

[0257] The lithium ion batteries of Examples 2-17 and the lithium ion batteries of Comparative Examples 1-3 were prepared in a similar manner to the lithium ion battery of Example 1, but using the corresponding positive electrode material of the preparation examples or comparative examples.

[0258] The button cells of Examples 2-17 and the button cells of Comparative Examples 1-3 were prepared in a similar manner to the button cell of Example 1, but using the corresponding positive electrode material of the preparation examples or comparative examples.

[0259] The button cells prepared in each of the above examples and comparative examples were subjected to capacity test, and the lithium ion batteries prepared in each of the above examples and comparative examples were subjected to storage test and cycle test.

[0260] Capacity test: Taking button cell as test object, at a voltage of 2.5V-4.55V, charge at 0.1C rate to 4.55V, then constant voltage charge at 4.55V to current≤0.05mA, stand for 2min, the charge capacity at this time is recorded as C0, then discharge at 0.1C rate to 2.5V, the discharge capacity at this time is gram capacity, recorded as D0, the first efficiency is D0 / C0x100%.

[0261] Storage test: Taking lithium ion battery as test object, in a constant temperature environment of 25℃, stand for 5min, discharge at 1 / 3C to 2.5V, stand for 5min, charge at 1 / 3C to 4.5V, then constant voltage charge at 4.5V to current≤0.05mA, stand for 5min, the charge capacity at this time is recorded as C0, then discharge at 1 / 3C to 2.8V, the discharge capacity at this time is initial gram capacity, recorded as D0; then charge the battery from 0.33C constant current to 4.5V and constant voltage to current≤0.05mA, stand for 5min, finally put into a high-low temperature box of 60℃, stand for 1h to make the battery temperature reach the target temperature, then store; after 15 days, take out, in a constant temperature environment of 25℃, repeat the above process, and record the capacity Dn(n=0,1,2…) every 15 days, calculate the capacity retention rate after 60 days storage: (D4-D0) / D0x100%.

[0262] Cycling test: taking lithium ion battery as test object, in constant temperature environment of 25℃, charging at 2.5V-4.45V voltage to 4.45V according to 1C rate, then constant voltage charging at 4.45V until current≤0.05mA, standing for 5min, then discharging to 2.5V according to 1C rate, recording discharging capacity, repeating the above process, obtaining capacity retention rate after cycling specified number of cycles, capacity retention rate = first cycle discharging capacity / discharging capacity at cycling specified number of cycles × 100%.

[0263] The test results of the above examples and comparative examples are shown in Table 3.

[0264] Table 3

[0265] From the comparison of the results of examples 1-17 and comparative examples 1-3, it can be seen that the lithium-rich manganese-based positive electrode material provided by the present application has high capacity and initial efficiency, and has excellent kinetics, cycling performance and high-temperature storage performance.

[0266] The above description of each example tends to emphasize the differences between each example, and the same or similar parts can be referred to each other, and for the sake of brevity, will not be repeated here.

[0267] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having substantially the same constitution and playing the same role and effect as the technical idea within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the constitutions of the embodiments are also included in the scope of the present application.

Claims

1. A lithium-rich manganese-based positive electrode material, comprising an inner core containing a lithium-rich manganese-based active material, wherein the lithium-rich manganese-based active material contains elemental S. The lithium-rich manganese-based positive electrode material has a residual stress of 0.2%-2.2%. The lithium-rich manganese-based positive electrode material has an oxygen defect index of >1.

82. The lithium-rich manganese-based positive electrode material has a Mn-O / Ni-O peak intensity ratio of 0.07-0.

19.

2. The lithium-rich manganese-based positive electrode material of claim 1, wherein, The lithium-rich manganese-based positive electrode material has a residual stress of 0.25%-2%.

3. The lithium-rich manganese-based positive electrode material according to any one of claims 1 to 2, wherein, The lithium-rich manganese-based positive electrode material has an oxygen defect index of 1.85-2.

75.

4. The lithium-rich manganese-based positive electrode material according to any one of claims 1 to 3, wherein, The lithium-rich manganese-based positive electrode material has a Mn-O / Ni-O peak intensity ratio of 0.075-0.

18.

5. The lithium-rich manganese-based positive electrode material according to any one of claims 1 to 4, wherein, The surface of the lithium-rich manganese-based active material contains oxygen site substitutional elemental S.

6. The lithium-rich manganese-based positive electrode material according to any one of claims 1 to 5, wherein, The mass percentage of elemental S in the lithium-rich manganese-based positive electrode material is 410ppm-980ppm.

7. The lithium-rich manganese-based positive electrode material according to any one of claims 1 to 6, wherein, The chemical formula of the lithium-rich manganese-based active material is Li[Li m Ni a Co b Mn c M d ]O 2-e Z e , wherein m+a+b+c+d=1, m>0, a+b+c+d<1, 0 M elements include one or more elements of Te, Se, Mg, Nb, Cr, Ce, Fe, Ta, B, V, Ti, Sn, W, and Mo, and Z elements include one or more elements of F, Cl, and Br.

8. The lithium-rich manganese-based positive electrode material according to any one of claims 1 to 7, wherein, a≥0.1, c≥0.5, d≥0.

9. The lithium-rich manganese-based positive electrode material according to any one of claims 1 to 8, wherein, The lithium-rich manganese-based positive electrode material further comprises a coating layer, which is coated on at least part of the surface of the inner core.

10. The lithium-rich manganese-based positive electrode material of claim 9, wherein, The coating layer contains a Q element, which includes one or more of Zr and Al.

11. The lithium-rich manganese-based positive electrode material of claim 10, wherein, The mass percentage of the Q element in the lithium-rich manganese-based positive electrode material is 500ppm-8000ppm.

12. The lithium-rich manganese-based positive electrode material of claim 11, wherein, The mass percentage of the Q element in the lithium-rich manganese-based positive electrode material is 3000ppm-6000ppm.

13. The lithium-rich manganese-based positive electrode material of any one of claims 1 to 12, wherein, The lithium-rich manganese-based positive electrode material has one or more of the following characteristics (1)-(4): (1) The lithium-rich manganese-based positive electrode material has a volume average particle size Dv50 of 6.0μm-10.0μm; (2) The lithium-rich manganese-based positive electrode material has a volume distribution diameter moment SPAN of 0.8-1.2; (3) the lithium-rich manganese-based positive electrode material has a specific surface area < 2.3 g / cm 2 ; (4) The coating layer is dot-shaped and coated on at least part of the surface of the inner core; (5) The thickness of the coating layer is 200nm-900nm.

14. The lithium-rich manganese-based cathode material of claim 13, wherein, The specific surface area of the lithium-rich manganese-based positive electrode material is 1.3 g / cm 2 -1.8 g / cm 2 . 15.A method for preparing a lithium-rich manganese-based positive electrode material, comprising the following steps: mixing an inner core containing a lithium-rich manganese-based active material and an ammonium sulfide solution to perform liquid phase treatment, so that the lithium-rich manganese-based active material contains elemental S, thereby preparing the lithium-rich manganese-based positive electrode material; The lithium-rich manganese-based positive electrode material has a residual stress of 0.2%-2.2%. The lithium-rich manganese-based positive electrode material has an oxygen defect index of >1.

82. The lithium-rich manganese-based positive electrode material has a Mn-O / Ni-O peak intensity ratio of 0.07-0.

19.

16. The method of making according to claim 15, wherein, The ratio between the mass of ammonium sulfide contained in the ammonium sulfide solution and the mass of the inner core is 3-7.

5.

17. The method of making according to any one of claims 15 to 16, wherein, The mass percentage concentration of the ammonium sulfide solution is 20wt%-30wt%.

18. The method of making according to any one of claims 15 to 17, wherein, The stirring rate of the liquid phase treatment is 600r / min-1000r / min, and the time is 10min-60min.

19. The method of making according to any one of claims 15 to 18, wherein, The method further comprises: mixing the inner core after the liquid phase treatment with a coating agent to perform a first sintering treatment, so as to form a coating layer on at least part of the surface of the inner core.

20. The method of making according to claim 19, wherein, The coating agent includes one or more of ZrF4 and AlF3.

21. The method of making according to any one of claims 19 to 20, wherein, The mass of the coating agent accounts for 0.09wt%-2.48wt% of the mass of the inner core.

22. The method of making according to any one of claims 19 to 21, wherein, The first sintering treatment comprises one or more of the following conditions: (1) the sintering temperature of the first sintering treatment is 350-550℃; (2) the sintering time of the first sintering treatment is 8-10h; (3) the heating rate of the first sintering treatment is 2-5℃ / min; (4) the sintering atmosphere of the first sintering treatment comprises air.

23. The method of making according to any one of claims 15 to 22, wherein, The preparation method of the core comprises: subjecting a mixture comprising a hydroxide precursor and a lithium source to a second sintering treatment; wherein the hydroxide precursor contains element Mn.

24. The method of manufacturing according to claim 23, wherein, The preparation method of the core comprises one or more of the following conditions: (1) the hydroxide precursor has the chemical formula Ni x Co y Mn z (OH)2, where x > 0.3, y < 0.1, z > 0.5; (2) the ratio between the molar amount of lithium element contained in the lithium source and the total molar amount of metal elements contained in the hydroxide precursor is 1.3-1.4; (3) the lithium source comprises one or more of lithium carbonate, lithium hydroxide monohydrate, lithium sulfate and lithium hydroxide; (4) the sintering temperature of the second sintering treatment is 780-900℃; (5) the sintering time of the second sintering treatment is 10-15h; (6) the heating rate of the second sintering treatment is 2-5℃ / min; (7) the sintering atmosphere of the second sintering treatment comprises air.

25. A positive electrode sheet comprising the lithium-rich manganese-based positive electrode material according to any one of claims 1-14 or prepared by the preparation method according to any one of claims 15-24.

26. The cathode sheet of claim 25, wherein, The compacted density of the positive electrode plate is 2.7 g / cm 3 - 3.1 g / cm 3 .

27. A lithium ion battery comprising the positive electrode sheet according to any one of claims 25-26.

28. The lithium-ion battery of claim 27, wherein, The lithium ion battery comprises a lithium-rich manganese-based positive electrode material, wherein the residual stress of the lithium-rich manganese-based positive electrode material is 3.5-5%, the oxygen defect index of the lithium-rich manganese-based positive electrode material is greater than 0 and less than 1.5, and the Mn-O / Ni-O peak intensity ratio of the lithium-rich manganese-based positive electrode material is greater than 0 and less than 0.

04.

29. An electric device comprising at least one of the positive electrode sheet according to any one of claims 25-26 and the lithium ion battery according to any one of claims 27-28.

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