Composite lithium nickel manganese oxide, preparation method thereof, positive electrode, battery and electrical device

Abstract

The application discloses composite lithium nickel manganese acid and a preparation method thereof, a positive electrode, a battery and an electric device. The composite lithium nickel manganese acid has a core-shell structure, the shell layer of the core-shell structure comprises a first coating layer and a second coating layer, the first coating layer coats a core of the core-shell structure, and the second coating layer coats the first coating layer; wherein the material of the core comprises lithium nickel manganese acid; the material of the first coating layer comprises doped lithium nickel manganese acid, the doped lithium nickel manganese acid contains doped elements, the doped elements comprise Te elements and M elements, the M elements comprise at least one of transition metal elements and VA group metal elements; and the material of the second coating layer comprises a compound formed by the doped elements. The composite lithium nickel manganese acid material has high voltage and energy density, and the chemical stability of the surface thereof and the chemical stability of the contact interface with electrolyte are excellent, and the storage and cycle performance in a high-temperature environment are excellent.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to composite lithium nickel manganese oxide and its preparation method, positive electrode, battery and electrical device. Background Art

[0002] Lithium nickel manganese oxide has relatively high voltage and energy density compared to lithium manganese oxide, such as a voltage upper limit of up to 5V for lithium and a voltage platform of about 4.7V, which allows the energy density of lithium nickel manganese oxide battery cells to be directly increased by about 20% (to a level close to the energy density of ternary batteries).

[0003] However, the valence element of lithium nickel manganese oxide during the delithiation process is not only divalent Ni 2+ , including the entire Ni 2+ The -O system loses electrons. As oxygen atoms lose some electrons, oxygen activity increases and stability decreases, which leads to instability in the contact interface between lithium nickel manganese oxide and the electrolyte, making side reactions prone to occur, thereby reducing the capacity of lithium nickel manganese oxide and the cycle performance of the battery. Summary of the Invention

[0004] In view of the above problems, the embodiments of the present application provide composite lithium nickel manganese oxide and its preparation method, positive electrode, battery and electrical device to solve the problem that the oxygen atoms contained in the existing lithium nickel manganese oxide are highly active and lead to reduced cycle performance.

[0005] In a first aspect, embodiments of the present application provide a composite lithium nickel manganese oxide. The composite lithium nickel manganese oxide of the embodiments of the present application has a core-shell structure, wherein the shell layer of the core-shell structure includes a first coating layer and a second coating layer, wherein the first coating layer coats the core of the core-shell structure, and the second coating layer coats the first coating layer; wherein the core comprises lithium nickel manganese oxide; the first coating layer comprises doped lithium nickel manganese oxide, wherein the doping element contained in the doped lithium nickel manganese oxide includes Te and M, wherein the M element includes at least one of a transition metal element and a Group VA metal element; and the second coating layer comprises a doping element compound formed by the doping element.

[0006] The composite lithium nickel manganese oxide material of the embodiment of the present application has a synergistic effect through its structure and the components it contains, thereby giving the composite lithium nickel manganese oxide of the embodiment of the present application a high voltage and energy density, and significantly improving the chemical stability of the surface of the composite lithium nickel manganese oxide material of the embodiment of the present application and the chemical stability of its contact interface with the electrolyte, thereby significantly improving the storage and cycle performance of the composite lithium nickel manganese oxide material of the embodiment of the present application, especially the storage and cycle performance in high temperature environments.

[0007] In some embodiments, the doping content of the doping element in the shell layer is 1000 ppm-10000 ppm.

[0008] By controlling the total doping amount of the doping elements in the shell layer, the activity of oxygen atoms on the surface of the lithium nickel manganese oxide spinel contained in the core and the first coating layer can be significantly reduced, significantly improving the stability of the oxygen atoms and the chemical stability of the surface of the composite lithium nickel manganese oxide in the embodiment of the present application. At the same time, the physical barrier effect of the second coating layer is enhanced.

[0009] In some embodiments, the doping molar ratio of the Te element to the M element is 1-10:0.5-5, and the doping amount of the Te element is higher than the doping amount of the M element.

[0010] By controlling the doping ratio of Te and M elements in the shell, the role of the nickel-poor phase functional coating layer of the shell can be enhanced, significantly reducing the activity of oxygen atoms on the surface of the lithium nickel manganese oxide spinel contained in the core and the first coating layer, improving the chemical stability of the surface of the composite lithium nickel manganese oxide of the embodiment of the present application. At the same time, the physical barrier effect of the second coating layer is enhanced.

[0011] In some embodiments, the doping element compound includes MTe.

[0012] In an exemplary embodiment, the transition metal element includes at least one of Nb, Mo, Ta, and W.

[0013] In an exemplary embodiment, the Group VA metal element includes Sb.

[0014] These M elements, together with the Te element, can dope the shell layer, significantly reducing the activity of oxygen atoms on the surface of the lithium nickel manganese oxide contained in the core and the first coating layer. Simultaneously, the M elements dope the composite lithium nickel manganese oxide, improving the electrochemical properties of the composite lithium nickel manganese oxide in the embodiments of the present application, including capacity.

[0015] In an exemplary embodiment, the doping element compound includes at least one of NbTe2, MoTe2, TaTe2, WTe2, and SbTe2. These doping element compounds MTe can form a chemically stable coating layer to enhance its physical barrier effect.

[0016] In an exemplary embodiment, the doped lithium nickel manganese oxide includes LiTe x Nb y Ni 0.5-x-y Mn 1.5-x-y O4、LiTe x Nb y Ni 0.5-x- y Mn 1.5-x-y O4、LiTe x W y Ni 0.5-x-y Mn 1.5-x-y O4 or LiTe x Tay Ni 0.5-x-y Mn 1.5-x-y At least one of O4; wherein x = 0.01-0.1, y = 0.005-0.05. The chemical activity of the oxygen atoms contained in these doped lithium nickel manganese oxides is significantly reduced, further improving the stability of the oxygen atoms on the surface of the composite lithium nickel manganese oxide and the stability of the contact interface between the composite lithium nickel manganese oxide and the electrolyte.

[0017] In some embodiments, the content of the doping element in the first cladding layer gradually decreases from the second cladding layer to the core body.

[0018] By distributing doping elements including Te and M in the first coating layer, the chemical activity of oxygen atoms on the contact surface between the composite lithium nickel manganese oxide and the electrolyte can be further reduced, the stability of the contact interface can be improved, and the electrochemical properties such as lithium ion transmission rate and energy density can be improved.

[0019] In some embodiments, the D V 50 Particle size is 3μm-15μm.

[0020] In some embodiments, the D of the composite lithium nickel manganese oxide is V 50 Particle size is 4μm-18μm.

[0021] In some embodiments, the shell layer satisfies any one of the following conditions:

[0022] The weight of the first coating layer is 0.5wt%-5wt% of the weight of the core body;

[0023] The weight of the second coating layer is 0.2wt%-1wt% of the weight of the core body;

[0024] The thickness of the first coating layer is 50nm-200nm;

[0025] The thickness of the second coating layer is 10 nm-100 nm.

[0026] By controlling the content of the first coating layer and the second coating layer in the composite lithium nickel manganese oxide in the embodiment of the present application or further controlling the thickness thereof, the stability of the oxygen atoms on the surface of the composite lithium nickel manganese oxide can be improved, the stability of the contact interface between the composite lithium nickel manganese oxide and the electrolyte can be improved, and the lithium ion transmission rate and the stability of the structure during the lithium insertion and extraction process can also be improved.

[0027] In some embodiments, the core and the composite lithium nickel manganese oxide are each independently cubic. The cubic composite lithium nickel manganese oxide has a high proportion of (100) crystal planes, thereby improving the composite lithium nickel manganese oxide in the above embodiments to have higher rate performance and capacity as well as crystal or structural stability.

[0028] In a second aspect, the present invention provides a method for preparing composite lithium nickel manganese oxide. The method comprises the following steps:

[0029] Providing granular materials containing lithium nickel manganese oxide;

[0030] forming a precursor coating layer containing doping elements on the surface of the particle material to form precursor-coated particles;

[0031] sintering the precursor coated particles so that the precursor coating layer forms a shell layer coating the nickel-containing lithium manganese oxide particles;

[0032] In which, the shell layer includes a first coating layer coating the lithium nickel manganese oxide particles and a second coating layer coating the first coating layer; the material of the first coating layer includes lithium nickel manganese oxide doped with the doping element, and the material of the second coating layer includes a doping element compound formed by the doping element; the doping element includes Te element and M element, and the M element includes at least one of a transition metal element and a VA group metal element.

[0033] The preparation method of composite lithium nickel manganese oxide in the embodiment of the present application can prepare composite lithium nickel manganese oxide with a core-shell structure material, and give the prepared composite lithium nickel manganese oxide high voltage and energy density, and chemical stability of its contact interface with the electrolyte, thereby significantly improving the storage and cycle performance of the composite lithium nickel manganese oxide material, especially the storage and cycle performance in high temperature environment.

[0034] In some embodiments, the content of the doping element in the precursor coating layer satisfies: the doping content of the doping element in the shell layer is 1000 ppm-10000 ppm.

[0035] In some embodiments, the sintering process includes the following two-stage sintering process:

[0036] The first stage of sintering treatment: temperature is 500-800℃, time is 6-10h;

[0037] The second stage of sintering treatment: temperature is 200-600℃, time is 3-6h.

[0038] By dividing the sintering process into two stages, the precursor coating layer can be formed into a shell layer including the first coating layer and the second coating layer, thereby improving the integrity of the shell layer and the efficiency of the sintering process.

[0039] In some embodiments, the crystal form of the granular material containing lithium nickel manganese oxide is a regular cube. The cubic crystal form of the granular material containing lithium nickel manganese oxide can ensure that the prepared composite lithium nickel manganese oxide has a cubic crystal form.

[0040] In some embodiments, the particle material containing lithium nickel-manganese oxide is prepared by a method comprising:

[0041] The manganese source is sintered in air to obtain Mn2O3;

[0042] The Mn2O3 is mixed with a lithium source and a nickel source in a certain proportion to obtain a lithium nickel-manganese oxide precursor;

[0043] The lithium nickel-manganese oxide precursor is subjected to a third sintering treatment to obtain the particle material containing lithium nickel-manganese oxide.

[0044] In some embodiments, the sintering temperature of the manganese source in air is 600-800°C.

[0045] In some embodiments, the sintering temperature of the lithium nickel-manganese oxide precursor is 200-800°C.

[0046] The particle material containing lithium nickel-manganese oxide prepared by the above solid-phase method can not only improve the generation of the particle material containing lithium nickel-manganese oxide, but also control the crystal form of the generated particle material containing lithium nickel-manganese oxide, such as cubic crystal form.

[0047] In a third aspect, the embodiments of the present application also provide a positive electrode. The positive electrode of the embodiments of the present application contains a positive electrode active layer, and the positive electrode active material contained in the positive electrode active layer comprises the composite lithium nickel-manganese oxide prepared by the method described above or prepared by the method described above.

[0048] The positive electrode of the embodiments of the present application has high capacity and high energy density. On this basis, the positive electrode active layer has a stable interface with the electrolyte, has few side reactions, and has high electrochemical performance such as storage and cycling performance, especially at high temperature.

[0049] In a fourth aspect, the embodiments of the present application provide a battery. The battery of the embodiments of the present application comprises a positive electrode and a negative electrode. The positive electrode is the positive electrode described above.

[0050] The battery of the embodiments of the present application has high voltage and high energy density, and the positive electrode has a stable interface with the electrolyte, thereby effectively improving the electrochemical performance of the battery of the embodiments of the present application, especially the excellent rate capability and cycling performance at high temperature.

[0051] In a fifth aspect, the embodiments of the present application provide an electric device. The electric device of the embodiments of the present application comprises the battery of the embodiments of the present application, and the battery is used to provide electric energy.

[0052] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0054] Figure 1 This is a schematic structural diagram of the composite lithium nickel manganese oxide according to an embodiment of the present application;

[0055] Figure 2 This is a schematic flow chart of the preparation method of composite nickel manganese oxide according to an embodiment of the present application;

[0056] Figure 3 This is a schematic structural diagram of an embodiment of a secondary battery of the present application;

[0057] Figure 4 for Figure 3 An exploded schematic diagram of the secondary battery shown;

[0058] Figure 5 This is a schematic structural diagram of an embodiment of a battery module of the present application;

[0059] Figure 6 This is a schematic structural diagram of an embodiment of a battery pack of the present application;

[0060] Figure 7 for Figure 6 Schematic diagram of the exploded structure of the battery pack shown;

[0061] Figure 8 Schematic diagram of an embodiment of an electric device including a secondary battery according to an embodiment of the present application as a power source;

[0062] Figure 9 For the embodiment of this application, the oxygen vacancy formation energy before and after lithium nickel manganese oxide doping is theoretically calculated; wherein, Figure 9 Figure a shows the oxygen vacancy formation energy before lithium nickel manganese oxide doping. Figure 9 Figure b shows the oxygen vacancy formation energy after lithium nickel manganese oxide is doped with different elements;

[0063] Figure 10 SEM images of lithium nickel manganese oxide are provided for Example A1-1, Example A2-1, and Comparative Examples A1-1 to A1-4 of the present application; wherein, Figure 10 FIG. 1a is an SEM image of the composite lithium nickel manganese oxide in Example A1-1, Figure 10 FIG. 1b is an SEM image of the composite lithium nickel manganese oxide in Example A2-1, Figure 10 FIG. 1c is an SEM image of the lithium nickel manganese oxide in Comparative Example A1-1, Figure 10 FIG. 1d is an SEM image of the composite lithium nickel manganese oxide in Comparative Example A1-2, Figure 10 FIG. 1e is an SEM image of the composite lithium nickel manganese oxide in Comparative Example A1-3, Figure 10 FIG. 1f is an SEM image of the composite lithium nickel manganese oxide in Comparative Example A1-4;

[0064] Figure 11 FIG. 2 is a cycle performance curve of the secondary battery cell in Examples B1-1 to B1-5, Examples B2-1 to B2-5, and Comparative Examples B1-1 to B2-1; wherein, Figure 11 FIG. 2a is a cycle performance curve of the secondary battery cell in Examples B1-1 to B1-5 and Comparative Examples B1-1 to B1-4, Figure 11 FIG. 2b is a cycle performance curve of the secondary battery cell in Examples B2-1 to B2-5 and Comparative Example B2-1.

[0065] The reference signs in the detailed description are as follows:

[0066] 10 - core;

[0067] 20 - shell layer, 21 - first coating layer, 22 - second coating layer;

[0068] 30 - battery cell, 31 - shell, 32 - electrode assembly, 33 - cover plate;

[0069] 40 - battery module;

[0070] 50 - battery pack, 51 - box, 52 - lower box. DETAILED DESCRIPTION

[0071] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0073] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0074] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0075] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0076] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0077] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0078] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0079] In the context of energy conservation and emission reduction, new energy technologies are developing rapidly, among which the research breakthroughs and applications of battery technology are the most significant, and lithium-ion batteries are the battery with the most prominent development momentum.

[0080] As battery applications become increasingly widespread, especially with the rapid development of electric vehicles in recent years, power batteries have developed rapidly and the demand has increased dramatically. At the same time, the electrochemical performance of batteries, especially the energy density and cycle performance of batteries, has also received increasing attention.

[0081] The positive electrode active material contained in the battery is one of the important factors affecting the battery's energy density and cycle performance. Among them, lithium nickel manganese oxide has relatively high voltage and energy density compared to lithium manganese oxide. For example, it has a high upper voltage limit of up to 5V to lithium and a voltage platform of approximately 4.7V. This allows the energy density of lithium nickel manganese oxide battery cells to be directly increased by about 20% (to a level close to the energy density of ternary batteries).

[0082] However, in lithium nickel manganese oxide, although in theory nickel +2 valence and manganese +4 valence, in reality, some oxygen vacancies are still generated during the synthesis process, accompanied by the reduction of manganese to +3 valence. This makes lithium nickel manganese oxide unable to completely escape the influence of lattice distortion, making it more susceptible to lattice distortion than conventional lithium manganese oxide. In addition, the higher voltage of lithium nickel manganese oxide also poses serious challenges to existing electrolyte systems. For example, conventional carbonate components are at risk of decomposition. Lithium nickel manganese oxide is also not resistant to hydrofluoric acid corrosion, and manganese will still be dissolved after corrosion.

[0083] Such as spinel material LiNi 0.5 Mn 1.5 When O4 (abbreviated as spinel LNMO) is used in a full-cell with a graphite negative electrode, the Ni-O system loses electrons during the charging process, and the oxygen atoms are stabilized and the oxidizability is increased, resulting in the deprotonation of the electrolyte solvent molecules on the surface of the positive electrode active material, accompanied by a large number of side reactions including surface oxygen loss, oxidation of solvent molecules to produce H + Acidification of electrolyte, dissolution of transition metal Mn ions. 2+ Li diffuses to the negative electrode and deposits to reduce the negative electrode SEI film + Conductivity, interface side reactions lead to serious capacity decay of graphite negative electrode. According to research, the main factors leading to the dissolution of spinel lithium nickel manganese oxide are the low surface stability of the positive electrode active material and the serious side reactions between the electrolyte and the interface. The internal reason is that the surface oxygen stability of the positive electrode active material decreases and the oxidation activity increases during charging, which oxidizes the electrolyte. At the same time, the surface loses oxygen to produce Mn 3 + , accelerating the disproportionation reaction and leading to the dissolution of Mn.

[0084] In order to overcome the above-mentioned problems of lithium nickel manganese oxide, the industry has also made a lot of improvement attempts. For example, coating, enlarging grains, and doping, but most of the existing methods may play a role in long-term stability at room temperature, but the modification of stability at high temperature is very limited. Experiments have shown that long-term stability at high temperature (especially high-temperature storage) is not positively correlated with other long-term stability (normal temperature cycle storage), that is, even if normal temperature cycling or storage is significantly improved, high-temperature storage may not be improved or may even worsen. Because a considerable part of the energy of the battery is consumed internally due to internal resistance during the charging and discharging process, resulting in heat, the actual service conditions of power batteries are usually high-temperature environments of 40-60°C, so high-temperature performance is more closely related to the actual service life of the battery.

[0085] For example, in a disclosed doped lithium nickel manganese oxide, it is doped with elements such as Ti and Al. In another disclosed doped lithium nickel manganese oxide, it is co-doped with anions (F, Cl ions) and cations (Li, Al, Cr, Co ions). However, studies have found that the capacity of existing doped lithium nickel manganese oxide is still relatively low, and there are serious interface problems. The reason is that its inactive rock salt phase content is relatively high, which reduces the overall capacity, and ignores the surface stability of the positive electrode active material, resulting in poor long-term stability of lithium nickel manganese oxide.

[0086] The research found that there are two reasons for the existing problems with the interface of lithium-doped nickel-manganese oxide: First, the valence element of lithium nickel-manganese oxide during the delithiation process is not only divalent Ni 2+ , including the entire Ni 2+ -O system loses electrons. As oxygen atoms lose some electrons, oxygen activity increases and stability decreases. Oxygen loss easily produces oxygen vacancies, which leads to poor stability of doped lithium nickel manganese. Figure 9 As shown in Figure a; secondly, the low-coordinated Ni on the surface cannot be oxidized to +4, and the surrounding oxygen atoms undergo oxidation reactions. The stability of the oxygen atoms increases with their oxidation activity, which easily oxidizes the electrolyte, reducing the overall capacity and cycle life. The reason for the lack of long-term stability is that doping cannot suppress the reaction between the doped lithium nickel manganese interface and the electrolyte; if Al is used for doping, the inactive further increases the oxidation reaction of the surface oxygen, resulting in continuous loss of oxygen on the positive electrode surface and Mn 2+ Ions dissolve, consuming electrolyte, generating gas and H + . Due to the positive electrode Mn 2+ Ions dissolve in the electrolyte and deposit on the negative electrode surface, forming the Li + The conductivity becomes worse, and H is generated in the electrolyte at the positive electrode. + It is reduced to generate H2 on the negative electrode surface, increasing gas production.

[0087] In order to effectively improve the electrochemical stability of lithium nickel manganese oxide, especially the long-term stability at high temperature, it is found through research that the lithium nickel manganese oxide is doped with tellurium (Te) and a transition metal element, and a double-layer coating structure is formed on the surface of the lithium nickel manganese oxide, which can effectively stabilize the oxygen atoms on the surface of the lithium nickel manganese oxide, specifically reduce the activity of the oxygen atoms, and also avoid direct contact between the lithium nickel manganese oxide and the electrolyte, effectively slow down the ability of the lithium nickel manganese oxide with a double-layer coating structure to react with the electrolyte at the contact interface, thereby endowing the lithium nickel manganese oxide with a double-layer coating structure with relatively high energy density, and significantly improving the electrochemical stability, especially the long-term stability at high temperature. Based on the findings of the inventors, the following scheme is proposed.

[0088] Composite lithium nickel manganese oxide

[0089] In a first aspect, the embodiments of the present application provide a composite lithium nickel manganese oxide. The composite lithium nickel manganese oxide of the embodiments of the present application has a core-shell structure, and the shell layer of the core-shell structure includes a first coating layer and a second coating layer; the first coating layer coats the core of the core-shell structure, and the second coating layer coats the first coating layer. As the embodiments of the present application, the structure of the composite lithium nickel manganese oxide of the embodiments of the present application is shown in FIG. 1, which includes a core 10 and a shell layer 20 coating the core 10, wherein the shell layer 20 includes a first coating layer 21 and a second coating layer 22, and the first coating layer 21 coats the core 10, and the second coating layer 22 coats the first coating layer 21. Figure 1

[0090] The material of the core 10 includes lithium nickel manganese oxide; the material of the first coating layer 21 includes doped lithium nickel manganese oxide, the doped lithium nickel manganese oxide contains doped elements including Te elements and M elements, and the M elements include at least one of transition metal elements and VA group metal elements; and the material of the second coating layer 22 includes a doped element compound formed by the doped elements.

[0091] In the composite lithium nickel manganese oxide material of the embodiments of the present application, the lithium nickel manganese oxide material constitutes the core 10, and the shell layer 20 forms a doped film layer on the surface of the core 10 to coat the core 10. The first coating layer 21 in the shell layer 20 is coated on the surface of the core 10, and the second coating layer 22 is coated on the outer surface of the first coating layer 21, that is, on the surface of the first coating layer 21 away from the core 10. Therefore, the first coating layer 21 constitutes an intermediate coating layer, and the first coating layer 21 includes doped lithium nickel manganese oxide containing doped elements such as Te elements and M elements, so that the first coating layer 21 constitutes a doped transition layer between the core 10 and the second coating layer 22.

[0092] ​The core 10 of the composite lithium nickel manganese oxide material of the present embodiment, due to its inclusion of lithium nickel manganese oxide, imparts high voltage and energy density to the composite lithium nickel manganese oxide of the present embodiment. The shell 20 containing Te and M elements inhibits the aggregation of Ni on the surface of the core 10, thereby forming a nickel-poor functional coating layer on the surface of the core 10.

[0093] Among them, the Te element contained in the first coating layer 21 in the shell 20 inhibits the aggregation of the Ni element, reduces the concentration of the Ni element in the first coating layer 21, and improves the stability of the oxygen atoms on the surface of the core 10 and the oxygen atoms in the first coating layer 21. In addition, the high-valent Te element and the M element can form strong covalent bonds with multiple surrounding oxygen atoms and provide more electrons to the surrounding oxygen atoms, significantly reducing the activity of the oxygen atoms on the surface of the lithium nickel manganese oxide contained in the core 10 and the first coating layer 21, and significantly improving the stability of the oxygen atoms. The second coating layer 22 containing the doped element compound constructs a coating layer with low Ni content or no Ni content, thereby acting as a physical barrier, isolating the core 10 and the first coating layer 21 from direct contact with the electrolyte, thereby inhibiting side reactions at the interface with the electrolyte, significantly improving the stability of the interface between the composite lithium nickel manganese oxide and the electrolyte in the embodiment of the present application, and alleviating or avoiding possible side reactions at the contact interface, such as reducing the H + At the same time, the first coating layer 21 containing doped lithium nickel manganese oxide can improve the surface delithiation stability of the composite lithium nickel manganese oxide material of the embodiment of the present application, while improving the transmission rate of lithium ions between the second coating layer 22 and the core 10, ensuring that the composite lithium nickel manganese oxide material of the embodiment of the present application has a high capacity and cycle stability. At the same time, the first coating layer 21 and the second coating layer 22 jointly construct the role of a mechanical barrier to avoid the increase of lithium nickel manganese oxide lattice strain during lithium insertion and extraction, resulting in particle breakage, thereby improving the structural stability of the composite lithium nickel manganese oxide material of the embodiment of the present application.

[0094] Therefore, the composite lithium nickel manganese oxide material of the embodiment of the present application has a synergistic effect through its structure and the components it contains, thereby giving the composite lithium nickel manganese oxide of the embodiment of the present application a high voltage and energy density, and significantly improving the chemical stability of the surface of the composite lithium nickel manganese oxide material of the embodiment of the present application and the chemical stability of its contact interface with the electrolyte, thereby significantly improving the storage and cycle performance of the composite lithium nickel manganese oxide material of the embodiment of the present application, especially the storage and cycle performance in high temperature environments.

[0095] In the embodiment, the D of the core 10 VThe particle size can be 3 μm-15 μm, further can be 5 μm-15 μm, 3 μm-10 μm, 5 μm-10 μm, etc. In the exemplary embodiment, it can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc. Typical but non-limiting particle sizes. V 50 is the volume distribution particle size, also known as the volume median particle size or median particle size of the particle, which refers to the particle size corresponding to when the cumulative particle size distribution percentage of the particle, such as the core body 10, reaches 50%.

[0096] By controlling the particle size of the core 10, the overall particle size of the composite lithium nickel manganese oxide particles of the embodiment of the present application can be adjusted. On the one hand, the content ratio of lithium nickel manganese oxide in the composite lithium nickel manganese oxide of the embodiment of the present application can be effectively guaranteed to improve the capacity, energy density and other performances of the composite lithium nickel manganese oxide of the embodiment of the present application; on the other hand, the compaction density of the composite lithium nickel manganese oxide of the embodiment of the present application can be improved.

[0097] In the embodiment, the crystal form of the core body 10 is a cubic crystal form. Specifically, the crystal of lithium nickel manganese oxide in the core body 10 is a cubic crystal form.

[0098] Among them, the cubic crystal form refers to a crystal with a cubic morphology, specifically, the crystal of lithium nickel manganese oxide has a cubic morphology. By controlling the crystal form of the core body 10 to a cubic crystal form, the proportion of the (100) crystal plane of the core body 10 is increased. The core body 10 with a high proportion of (100) crystal planes has higher rate performance and crystal stability, thereby significantly improving the capacity and stability of the core body 10, and also improving the rate performance of the core body 10. Therefore, the core body 10 of the cubic crystal form can significantly improve the capacity and rate performance of the composite lithium nickel manganese oxide in the embodiment of the present application, and the crystal structure is stable.

[0099] In addition, based on the characteristics of the lithium nickel manganese oxide contained in the core 10 , the lithium nickel manganese oxide should not contain the doping elements in the shell 20 to ensure the capacity of the lithium nickel manganese oxide contained in the core 10 .

[0100] In the embodiments, the core 10 of each of the above embodiments may further contain other additives or modifiers, such as, but not limited to, lithium-supplementing additives, to irreversibly remove lithium ions during the initial charge process to ensure the capacity of the lithium nickel manganese oxide. Furthermore, the other additives or modifiers may be physically mixed with the lithium nickel manganese oxide contained in the core 10, or may be mixed in a phase.

[0101] For the purpose of improving the electrochemical properties of lithium nickel manganese oxide, the lithium nickel manganese oxide contained in the core 10 in the above embodiments can also be doped lithium nickel manganese oxide, such as lithium or transition metal element doping to improve the relevant electrochemical properties of lithium nickel manganese oxide. As shown in the exemplary embodiment, the doping element can be but is not limited to one or more elements selected from lithium, magnesium, aluminum, etc.

[0102] In some embodiments, when the doping element M contained in the shell layer 20 of the composite lithium nickel manganese oxide of this embodiment includes a transition metal element, the transition metal element may include at least one of Nb, Mo, Ta, and W. When the M element in the shell layer 20 includes a Group VA metal element, the Group VA metal element may be Sb. Therefore, the doping element M in the shell layer 20 of the composite lithium nickel manganese oxide of each embodiment above may include at least one of Nb, Mo, Ta, W, Sb, and the like.

[0103] On the one hand, the doping elements shown by the M element can realize the doping of the shell 20 together with the doping element Te in the shell 20, so that the M element forms a strong covalent bond with multiple surrounding oxygen atoms and provides more electrons to the surrounding oxygen atoms, significantly reducing the activity of the oxygen atoms on the surface of the lithium nickel manganese oxide such as spinel lithium nickel manganese oxide contained in the core 10 and the first coating layer 21, and significantly improving the stability of the oxygen atoms, such as Figure 9 As shown in Figure b, the chemical stability of the composite lithium nickel manganese oxide surface of the embodiment of the present application is improved. At the same time, the M element achieves doping of the composite lithium nickel manganese oxide, improving other electrochemical properties of the composite lithium nickel manganese oxide of the embodiment of the present application, such as capacity.

[0104] In the embodiment, the total molar doping ratio of the Te element and the M element in the shell 20, that is, the first coating layer 21 and the second coating layer, can be 1-10:0.5-5, and can further be 2:(1-1.02). Among them, the total molar doping amount of the Te element in the shell 20, that is, the first coating layer 21 and the second coating layer 22, can be controlled to account for 1‰-10% of the composite lithium nickel manganese oxide in the embodiment of the present application, and the total molar doping amount of the M element in the shell 20, that is, the first coating layer 21 and the second coating layer 22, can be controlled to account for 0.5‰-5% of the composite lithium nickel manganese oxide in the embodiment of the present application. Among the doping elements in the shell 20, the doping amount of the Te element can be controlled to be higher than the doping amount of the M element. By controlling the doping ratio and respective doping amounts of the Te element and the M element in the shell 20, and further controlling the doping amount of the Te element and the M element in the composite lithium nickel manganese oxide of the embodiment of the present application, on the one hand, the Te element can be fully utilized to inhibit the aggregation of the Ni element, reduce the concentration of the Ni element in the first coating layer 21, and improve the role of the nickel-poor phase functional coating layer of the shell 20; on the other hand, the doping ratio of the Te element and the M element is controlled, and the high-valent Te element and the M element in the first coating layer 21 are increased to form strong covalent bonds with multiple oxygen atoms around and provide more electrons to the surrounding oxygen atoms, significantly reducing the activity of the oxygen atoms on the surface of the lithium nickel manganese oxide contained in the core 10 and the first coating layer 21, improving the stability of the oxygen atoms, and improving the chemical stability of the surface of the composite lithium nickel manganese oxide of the embodiment of the present application. At the same time, the doping ratio of the Te element and the M element is controlled, the physical barrier effect of the second coating layer 22 is improved, the stability of the contact interface between the composite lithium nickel manganese oxide and the electrolyte in the embodiment of the present application is improved, and the possible side reactions of the contact interface are further reduced or avoided.

[0105] In the embodiment, the doping elements in the shell 20, that is, the total doping content of the Te element and the M element in the first coating layer 21 and the second coating layer 22 in the shell 20 can be 1000ppm-10000pm, and further can be 4000ppm-8000ppm. In the exemplary embodiment, the total doping content of the Te element and the M element in the shell 20 can be 1000ppm, 2000ppm, 3000ppm, 4000ppm, 5000ppm, 6000ppm, 7000ppm, 8000ppm, 9000ppm, 10000ppm, etc., which are typical but non-limiting contents. By controlling the total doping amount of the doping elements in the shell 20, the activity of the oxygen atoms on the surface of the lithium nickel manganese oxide contained in the core 10 and the first coating layer 21 can be significantly reduced, the stability of the oxygen atoms can be significantly improved, and the chemical stability of the surface of the composite lithium nickel manganese oxide of the embodiment of the present application can be improved. At the same time, the physical barrier effect of the second coating layer 22 is improved, and the stability of the contact interface between the composite lithium nickel manganese oxide and the electrolyte in the embodiment of the present application is improved.

[0106] In an embodiment, the weight of the first coating layer 21 contained in the shell 20 is 0.5wt%-5wt% of the weight of the core body 10, and further is 1wt%-3wt%. In a demonstration example, the weight of the first coating layer 21 can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt% and other typical but non-limiting weight proportions of the weight of the core body 10.

[0107] In other embodiments, the thickness of the first coating layer 21 can be controlled to be 50 nm-200 nm, and further can be 50 nm-100 nm. In exemplary embodiments, the thickness of the first coating layer 21 can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 200 nm, etc. Typical but non-limiting thicknesses. The thickness of the first coating layer 21 should be understood as the distance from the surface of the first coating layer 21 away from the core body 10 to the surface in contact with the core body 10.

[0108] By controlling the content of the first coating layer 21 in the composite lithium nickel manganese oxide of the embodiment of the present application or further controlling its thickness, such as controlling it within the above-mentioned content range and thickness range, the above-mentioned function of the first coating layer 21 can be fully exerted, thereby improving the stability of the oxygen atoms on the surface of the composite lithium nickel manganese oxide, improving the stability of the contact interface between the composite lithium nickel manganese oxide and the electrolyte, and reducing side reactions at the contact interface. It can also increase the lithium ion transmission rate of the first coating layer 21 and improve the structural stability of the composite lithium nickel manganese oxide of the embodiment of the present application during the lithium insertion and extraction process.

[0109] The distribution position and the materials contained in the first coating layer 21, the second coating layer 22 and the core 10 in the above-mentioned embodiments, the first coating layer 21 can be understood as a transition layer between the second coating layer 22 and the core 10. Therefore, in the embodiment, the content of the doping elements (including Te and M elements) in the first coating layer 21 gradually decreases from the second coating layer 22 to the core 10. As in the embodiment, it can be a gradient decrease, or it can be gradually reduced by diffusion or free diffusion. By controlling the distribution of doping elements such as Te and M elements in the first coating layer 21, the above-mentioned effect of the first coating layer 21 can be further improved, such as further reducing the content of Ni elements on the contact surface between the first coating layer 21 and the second coating layer 22, reducing the chemical activity of oxygen atoms on the contact surface, improving the stability of the contact interface, and at the same time improving the lithium ion transmission rate and avoiding the doping of these doping elements into the core 10, thereby improving the energy density and other electrochemical properties of the composite lithium nickel manganese oxide in the embodiment of the present application.

[0110] In the exemplary embodiment, the doping elements contained in the first cladding layer 21 in the above embodiments include Te and M elements, and the material of the first cladding layer 21 may include LiTe x Nb y Ni 0.5-x-y Mn 1.5-x-y O4、LiTe x Nb y Ni 0.5-x-y Mn 1.5-x- y O4、LiTe x W y Ni 0.5-x-y Mn 1.5-x-y O4 or LiTe x Ta y Ni 0.5-x-y Mn 1.5-x-y At least one of O4; wherein x = 0.01-0.1, y = 0.005-0.05. In the exemplary embodiment, x can be a typical but non-limiting value such as 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, and y can be a typical but non-limiting value such as 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, and 0.05. The chemical activity of the oxygen atoms contained in these doped lithium nickel manganese oxides is significantly reduced, thereby enhancing the above-mentioned role of the first coating layer 21, further improving the stability of the oxygen atoms on the surface of the composite lithium nickel manganese oxide, improving the stability of the contact interface between the composite lithium nickel manganese oxide and the electrolyte, and reducing side reactions between the contact interfaces.

[0111] Based on the function of the first coating layer 21, the coating of the core 10 can be fully coated or partially coated. Among them, the partial coating can be composed of a continuous or discontinuous coating layer. It is relatively ideal to fully coat the core 10 so that the first coating layer can fully act on the surface of the core 10, reduce the chemical activity of oxygen atoms on the surface of the core 10, and improve the electrochemical stability of the composite nickel manganese oxide surface, especially improve the electrochemical properties of the composite nickel manganese oxide, such as high-temperature storage and cycle performance.

[0112] The material of the second coating layer 22 contained in the shell layer 20 of the composite lithium nickel manganese oxide of the embodiments of the present application, i.e., the MTe contained in the doped element compound, can be different according to the M. For example, when the doped element M is at least one of the transition metal elements and the VA group metal elements described above, the doped element compound MTe can include a compound of at least one of the transition metal elements and the VA group metal elements and Te. For example, when the M includes at least one of Nb, Mo, Ta, W, and Sb, the doped element compound MTe can include at least one of NbTe2, MoTe2, TaTe2, WTe2, and SbTe2. The doped element compound MTe can form a chemically stable coating layer, improve the physical barrier effect, and significantly improve the chemical stability of the surface of the composite lithium nickel manganese oxide of the embodiments of the present application and the stability of the interface with the electrolyte.

[0113] In some embodiments, the weight of the second coating layer 22 contained in the shell layer 20 of the composite lithium nickel manganese oxide of the embodiments of the present application is 0.2 wt% to 1 wt% of the weight of the core 10. For example, the weight of the second coating layer 22 can be 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, or the like, of the weight of the core 10.

[0114] In other embodiments, the thickness of the second coating layer 22 can be controlled to be 10 nm to 100 nm, and further can be 10 nm to 30 nm. For example, the thickness of the second coating layer 22 can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or the like. The thickness of the second coating layer 22 should be understood as the distance from the surface of the second coating layer 22 away from the first coating layer 21 to the surface of the second coating layer 22 in contact with the first coating layer 21.

[0115] By controlling the content of the second coating layer 22 in the composite lithium nickel manganese oxide of the embodiments of the present application and further controlling the thickness thereof, such as controlling the content and the thickness in the ranges described above, the above-mentioned effects of the second coating layer 22 can be fully exerted, such as further improving the chemical stability of the oxygen atoms on the surface of the second coating layer 22 in contact with the first coating layer 21 and improving the physical barrier effect of the second coating layer 22, further inhibiting the side reaction at the interface of the composite lithium nickel manganese oxide of the embodiments of the present application with the electrolyte, and further significantly improving the stability of the interface of the composite lithium nickel manganese oxide of the embodiments of the present application with the electrolyte.

[0116] Based on the function of the second coating layer 22, it is ideal to fully cover the first coating layer 21 to give full play to the physical barrier function of the second coating layer 22 and completely suppress the side reactions at the contact interface between the composite lithium nickel manganese oxide and the electrolyte in the embodiment of the present application.

[0117] In some embodiments, the composite lithium nickel manganese oxide in each of the above embodiments is a cubic crystal. As shown in the exemplary embodiment, the core 10 contained in the composite lithium nickel manganese oxide in each of the above embodiments is a cubic crystal, and the composite lithium nickel manganese oxide is a cubic crystal. By controlling the crystal of the composite lithium nickel manganese oxide to be a cubic crystal, or on this basis, simultaneously controlling the crystal form of the core 10 to be a cubic crystal, the proportion of the (100) crystal plane of the composite lithium nickel manganese oxide in each of the above embodiments can be increased compared with other crystal forms such as an octahedral crystal, thereby improving the composite lithium nickel manganese oxide in each of the above embodiments to have higher rate performance and capacity as well as crystal or structural stability.

[0118] In some embodiments, the D of the composite lithium nickel manganese oxide in the above embodiments is V 50 particle size is 4μm-18μm, further can be 4μm-8μm, 4μm-10μm, in the exemplary embodiment, the D of the composite lithium nickel manganese oxide V The particle size of 50 can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm and other typical but non-limiting particle sizes. Controlling the particle size of the composite lithium nickel manganese oxide within this range can improve the electrochemical properties of the composite lithium nickel manganese oxide of the embodiment of the present application, including compaction density. The D V 50 particle size can pass through the core body 10 D V 50 particle size, the shell 20 includes the first coating layer 21 and the second coating layer 22 thickness control and adjustment, to achieve the D of the composite lithium nickel manganese oxide V 50 particle size control and adjustment.

[0119] Preparation method of composite lithium nickel manganese oxide

[0120] In the second aspect, the present invention provides a method for preparing composite lithium nickel manganese oxide. The process flow of the method for preparing composite lithium nickel manganese oxide in the present invention is as follows: Figure 2 As shown, the preparation method of composite lithium nickel manganese oxide in the embodiment of the present application may include the following steps:

[0121] S10: providing a granular material containing lithium nickel manganese oxide;

[0122] S20: forming a precursor coating layer containing doping elements on the surface of the particle material to form precursor-coated particles;

[0123] S30: sintering the precursor-coated particles (referred to as the fourth sintering process, the same below) so that the precursor coating layer forms a shell layer coating the nickel-containing lithium manganese oxide particles.

[0124] In the preparation method of composite lithium nickel manganese oxide in the embodiment of the present application, the granular material containing lithium nickel manganese oxide in step S10 constitutes the core of the precursor coated particles in step S20. Through the fourth sintering treatment in step S30, the precursor coating layer contained in the precursor coated particles is sintered to form a shell layer, which coats the lithium nickel manganese oxide particles to form the composite lithium nickel manganese oxide in the embodiment of the above text application. Since the composite lithium nickel manganese oxide in the embodiment of the above text application is prepared, the precursor coating layer in step S20 is a precursor coating layer that forms the shell layer 20 contained in the composite lithium nickel manganese oxide in the embodiment of the above text application, and therefore, the material of the precursor coating layer should contain a Te element source and an M element source. Among them, the M element in the M element source is the doped M element contained in the composite lithium nickel manganese oxide in the embodiment of the above text application. After the fourth sintering treatment in step S30, the lithium nickel manganese oxide particles contained in the precursor coated particles form the core body 10 of the composite lithium nickel manganese oxide of the above-mentioned embodiment of the application, and the precursor coating layer forms a shell layer 20. Specifically, the Te element and the M element provided by the Te element source and the M element source contained in the precursor coating layer form a first coating layer 21 containing doped lithium nickel manganese oxide and a second coating layer 22 forming a doped element compound.

[0125] Therefore, the preparation method of the composite lithium nickel manganese oxide in the embodiment of the present application can prepare the composite lithium nickel manganese oxide with a core-shell structure material of the embodiment of the present application, and give the prepared composite lithium nickel manganese oxide high voltage and energy density, and the surface of the composite lithium nickel manganese oxide prepared by the shell layer formed by it is a nickel-poor functional layer, and can effectively reduce the chemical activity of oxygen atoms on the surface of the composite lithium nickel manganese oxide, thereby improving the chemical stability of the contact interface between the prepared composite lithium nickel manganese oxide and the electrolyte, thereby significantly improving the storage and cycle performance of the composite lithium nickel manganese oxide material, especially the storage and cycle performance under high temperature environment.

[0126] Step S10:

[0127] The lithium nickel manganese oxide-containing particle material in step S10 is the material constituting the core body 10 contained in the composite lithium nickel manganese oxide in the embodiment of the above application, or is directly used as the core body 10 contained in the composite lithium nickel manganese oxide in the embodiment of the above application.

[0128] Therefore, the particle size of the granular material containing lithium nickel manganese oxide can be directly controlled, and finally the particle size of the core body 10 contained in the composite lithium nickel manganese oxide can be controlled. For example, the D of the granular material containing lithium nickel manganese oxide can be controlled. V 50 particle size control will ultimately control the D of the core contained in the composite nickel manganese oxide V 50 particle size is the D of the core body 10 contained in the composite nickel manganese oxide lithium of the above application example.V 50 particle size range.

[0129] In the embodiment, the lithium nickel manganese oxide-containing granular material can be prepared according to a preparation method of lithium nickel manganese oxide, such as at least one of a solid phase method, a solution precipitation method, and a gel method to prepare the lithium nickel manganese oxide-containing granular material in step S10.

[0130] In an embodiment, the granular material containing lithium nickel manganese oxide may be a cubic crystal. The granular material containing lithium nickel manganese oxide in the cubic crystal form can construct a cubic crystal matrix, thereby ensuring that the prepared composite lithium nickel manganese oxide has a cubic crystal form.

[0131] When the granular material containing lithium nickel manganese oxide in step S10 of the gel method is prepared by a gel method, such as preparing the granular material in a cubic crystal form, the granular material containing lithium nickel manganese oxide is prepared by the following method:

[0132] Step S11: preparing a soluble nickel source solution and a soluble manganese source solution respectively;

[0133] Step S12: adding a complexing agent (referred to as the first complexing agent, the same below) to the soluble nickel source solution and the soluble manganese source solution respectively to carry out a complexing reaction (referred to as the first complexing reaction, the same below) to obtain a nickel-containing gel and a manganese-containing gel, respectively;

[0134] Step S13: After drying the nickel-containing gel and the manganese-containing gel, they are mixed with a lithium source in proportion (referred to as the first mixing process, the same below) to obtain a nickel-containing lithium manganate precursor (referred to as the first nickel-containing lithium manganate precursor, the same below);

[0135] Step S14: sintering the first nickel-containing lithium manganese oxide precursor (referred to as the first sintering treatment first complexing agent, the same below) to obtain a granular material containing nickel-containing lithium manganese oxide.

[0136] The gel method can effectively control the morphology of the granular material containing lithium nickel manganese oxide and improve the electrochemical properties such as the capacity of lithium nickel manganese oxide.

[0137] Among them, the soluble nickel source and soluble manganese source in step S11 can be the soluble nickel source and manganese source for preparing lithium nickel manganese oxide. For example, in the embodiment, the soluble nickel source can include at least one of acetate, carbonate, nitrate, sulfate, and hydroxide; the soluble manganese source can include at least one of acetate, carbonate, nitrate, sulfate, and hydroxide.

[0138] In some embodiments, the concentration of the soluble nickel source solution in step S11 may be 0.5 to 1.0 mol / L, and the concentration of the soluble manganese source solution may be 0.5 to 1.0 mol / L. The concentrations of these soluble salt solutions may be adjusted as needed, and the solvent for preparing the soluble nickel source solution and the soluble manganese source solution may be water.

[0139] In step S12, after the first complexing agent is added to the soluble nickel source solution and the soluble manganese source solution, the first complexing agent can complex nickel ions and manganese ions, respectively, to generate nickel-containing gel and manganese-containing gel, respectively.

[0140] In an embodiment, the first complexing agent comprises at least one of citric acid, oxalic acid, glutamic acid, polypropylene glycol, PVDF, and polyacrylamide. These first complexing agents are capable of effectively complexing with nickel ions and manganese ions to form nickel-containing gel and manganese-containing gel, respectively. To fully complex the nickel ions and manganese ions, the first complexing agent should be in an appropriate excess relative to the soluble nickel source and the soluble manganese source, respectively.

[0141] In the embodiment, the conditions for the first complexation reaction respectively performed after adding the first complexing agent to the soluble nickel source solution and the soluble manganese source solution can be set to satisfy at least any one of the following conditions:

[0142] The temperature of the first complexation reaction is 40-100°C;

[0143] The pH value of the first complexation reaction system is 7-11;

[0144] By controlling and adjusting the conditions of the first complexation reaction, the relevant properties of the nickel gel and the manganese-containing gel can be controlled respectively, so that the lithium nickel manganate precursor prepared in step S13 can be subjected to the first sintering treatment in step S14 to prepare a granular material containing lithium nickel manganate in a cubic crystal form. The prepared granular material containing lithium nickel manganate has a high proportion of (100) crystal planes, thereby making the prepared granular material containing lithium nickel manganate have relatively high rate performance and capacity as well as crystal or structural stability.

[0145] In step S13, the nickel-containing gel and the manganese-containing gel prepared in step S12 are mixed with a lithium source after being dried, to prepare a precursor of the lithium nickel-manganese oxide particle material in step S10. Therefore, the mixing ratio of the dried nickel-containing gel, the manganese-containing gel and the lithium source should satisfy the molar ratio of the elements in the lithium nickel-manganese oxide. In the embodiment, the dried nickel-containing gel, the manganese-containing gel and the lithium source are mixed in a molar ratio of (nickel+manganese) to lithium of (0.4+1.5)-(0.6+1.5):1.01-1.1. In the ratio of (0.4+1.5)-(0.6+1.5):1.01-1.1, 0.4 and 0.6 represent the molar amount of nickel, 1.5 represents the molar amount of manganese, and 1.01-1.1 represents the molar amount of lithium.

[0146] In the embodiment, the lithium source can include at least one lithium salt selected from acetate, carbonate, nitrate, sulfate, hydroxide and oxide.

[0147] After the first sintering treatment in step S14, the first lithium nickel-manganese oxide precursor in step S13 is sintered to form a lithium nickel-manganese oxide, i.e., the lithium nickel-manganese oxide particle material in step S10, and preferably a lithium nickel-manganese oxide particle material having a cubic crystal structure.

[0148] In the embodiment, the first sintering treatment can include two-stage sintering treatment as follows:

[0149] First-stage sintering treatment: temperature of 500-800°C, time of 6-10h;

[0150] Second-stage sintering treatment: temperature of 200-600°C, time of 3-6h.

[0151] By dividing the first sintering treatment into two stages, the efficiency of the first sintering treatment can be improved, and the proportion of the (100) crystal plane in the lithium nickel-manganese oxide crystal can be increased.

[0152] When the lithium nickel-manganese oxide particle material in step S10 is prepared by the solid phase method, the lithium nickel-manganese oxide particle material is prepared by a method including the following steps:

[0153] Step S15: sintering treatment (second sintering treatment, the same below, to distinguish the first sintering treatment and the fourth sintering treatment) of the manganese source in air to obtain Mn2O3;

[0154] Step 16: Mn2O3 is mixed with a lithium source and a nickel source in proportion (referred to as a second mixing process, the same below, to distinguish it from the first mixing process above) to obtain a nickel-containing lithium manganate precursor (referred to as a second nickel-containing lithium manganate precursor, the same below, to distinguish it from the first nickel-containing lithium manganate precursor above);

[0155] Step 17: The second nickel-containing lithium manganese oxide precursor is sintered (referred to as the third sintering process, the same below, to distinguish the first sintering process, the second sintering process and the fourth sintering process above) to obtain a granular material containing nickel-containing lithium manganese oxide.

[0156] During the second sintering process in step S15, the manganese source is sintered to produce Mn2O3. The conditions of the second sintering process can be controlled. For example, in the embodiment, the temperature of the second sintering process is controlled at 600-800°C to produce cubic Mn2O3. The second sintering process should be sufficient, such as, but not limited to, 3 hours.

[0157] In some embodiments, the manganese source includes at least one of a divalent manganese salt (such as but not limited to MnO), a tetravalent manganese salt (such as but not limited to pure β-MnO2), a manganese nitrate (manganese nitrate hexahydrate), a manganese carbonate, and the like.

[0158] In an exemplary embodiment, when the manganese source is manganese carbonate, the carbonate can be prepared as follows:

[0159] A soluble manganese salt and sodium carbonate, sodium bicarbonate, or ammonium bicarbonate (any soluble salt containing carbonate) are dissolved in distilled water at a ratio of 1:1 to form a stable solution, and the pH of the solution is adjusted to 7.5-9. The solution is heated at 150°C for 10 hours to react, and finally rinsed, impurities removed, evaporated, concentrated, and crystallized to obtain manganese carbonate powder.

[0160] The second mixing process in step 16 is to prepare the Mn2O3 in step S15, such as cubic Mn2O3, to be uniformly mixed with the lithium source and the nickel source. In the exemplary embodiment, the second mixing process can be solid phase mixing, such as including but not limited to grinding process.

[0161] In addition, the mixing ratio of Mn2O3 to the lithium source and the nickel source should satisfy the molar ratio of the elements contained in lithium nickel manganese oxide, such as the molar stoichiometric ratio of Li:Mn:Ni of 1.01-1.1:1.5:0.5.

[0162] In an exemplary embodiment, the lithium source may include at least one lithium salt selected from the group consisting of acetate, carbonate, nitrate, sulfate, hydroxide, and oxide. The nickel source may include at least one selected from the group consisting of acetate, carbonate, nitrate, sulfate, and hydroxide.

[0163] After the third sintering process in step S17, the second nickel-containing lithium manganate precursor in step S16 is sintered to produce nickel-containing lithium manganate, which is the nickel-containing lithium manganate particle material in step S10. If the Mn2O3 produced in step S15 has a cubic crystal structure, the nickel-containing lithium manganate particles produced after the third sintering process in step S17 also have a cubic crystal structure.

[0164] In the embodiment, the temperature of the third sintering treatment can be 200-800° C., further 400-800° C., 600-800° C., and the time of the third sintering treatment should be sufficient, such as but not limited to 10 hours.

[0165] In an exemplary embodiment, the third sintering process may also be performed in accordance with the first sintering process in step S14, for example, the third sintering process may include the following two stages:

[0166] The first stage of sintering treatment: temperature is 500-800℃, time is 6-10h;

[0167] The second stage of sintering treatment: temperature is 200-600℃, time is 3-6h.

[0168] The above-mentioned solid-phase method is used to prepare the granular material containing lithium nickel manganate. On the basis of improving the generation of the granular material containing lithium nickel manganate, the crystal form of the generated granular material containing lithium nickel manganate can also be controlled, such as controlling it to be a cubic crystal form and giving it a high (100) crystal plane ratio.

[0169] Step S20:

[0170] The precursor coating layer formed in step S20 is the precursor coating layer for forming the shell layer 20 contained in the composite lithium nickel manganese oxide in the embodiment of the above application. Therefore, the material of the precursor coating layer should contain Te element source and M element source.

[0171] In the embodiment, the method of forming the precursor coating layer containing the doping element on the surface of the particle material in step S01 includes at least one of a solid phase method, a precipitation method, and a gel method.

[0172] In the embodiment, when a solid phase method is used to form a precursor coating layer containing a doping element, the solid phase method for forming a precursor coating layer containing a doping element includes the following steps:

[0173] S21: The first doping element source and the granular material are mixed in proportion (recorded as the third mixing process, the same below, to distinguish the first mixing process from the second mixing process above) to obtain a solid phase mixture.

[0174] In the embodiment, when a precipitation method is used to form a precursor coating layer containing a doping element, the precipitation method includes the following steps:

[0175] S22: mixing the solution of the soluble second doping element source and the particulate material in proportion (referred to as the fourth mixing process, the same below, to distinguish the first mixing process, the second mixing process, and the third mixing process above) to prepare a mixed solution;

[0176] S23: adding a precipitant to the mixed solution to form a precipitate layer containing the doping element on the surface of the granular material.

[0177] In the embodiment, when a gel method is used to form a precursor coating layer containing doping elements, the gel method includes the following steps:

[0178] S24: performing a complex reaction (referred to as a second complex reaction, hereinafter the same, to distinguish the first complex reaction) on a solution of a soluble third doping element source and a complexing agent (referred to as a second complexing agent, hereinafter the same, to distinguish the first complexing agent) to generate a doping element gel;

[0179] S25: Mixing the doping element gel and the granular material in proportion (recorded as the fifth mixing process, the same below, to distinguish the first to fourth mixing processes above) to obtain a gel mixture.

[0180] Since the precursor coating layer formed in step S20 is the precursor coating layer for forming the shell layer 20 contained in the composite lithium nickel manganese oxide in the above-mentioned application embodiment, no matter which of the above-mentioned methods is used to prepare the precursor coating layer containing doping elements, the first doping element source in step S21, the second doping element source in step S22, and the third doping element source in step S24 all include Te element source and M element source.

[0181] In the embodiment, the first doping element source in step S21, the second doping element source in step S22, and the third doping element source in step S24 can independently include at least one salt selected from acetate, carbonate, nitrate, sulfate, and hydroxide, and of course, a salt containing the element Te and the element M. Since the first doping element source in step S21 is prepared by a solid-phase method, the first doping element source can also be an insoluble compound containing the element Te and an insoluble compound containing the element M, such as an oxide of Te and an oxide of M.

[0182] At the same time, in the embodiment, the amount of Te element source and M element source contained in the precursor coating layer formed in step S20 should also satisfy that the precursor coating layer forms the shell layer 20 contained in the composite lithium nickel manganese oxide in the embodiment of the above application after the fourth sintering treatment in step S30 above. As in the embodiment, the content of the doping element such as the first doping element source in step S21, the second doping element source in step S22, and the third doping element source in step S24 in the precursor coating layer satisfies: the doping content of the doping element in the shell layer formed after the fourth sintering treatment in step S30 above is 1000ppm-10000ppm.

[0183] When the precursor coating layer is prepared by the above gel method, in the embodiment, the conditions of the second complexation reaction in step S24 at least meet any one of the following conditions:

[0184] The temperature of the second complexation reaction can be 40-100°C;

[0185] The pH value of the second complexation reaction system can be 7-11;

[0186] The second complexing agent may include at least one of citric acid, oxalic acid, glutamic acid, polypropylene glycol, PVDF, and polyacrylamide.

[0187] The second complexation reaction conditions can effectively form a precursor coating layer on the surface of the lithium nickel manganese oxide particle material and improve the film uniformity and integrity of the precursor coating layer.

[0188] In some embodiments, the precursor coating formed in step S20 above may further contain a lithium nickel manganese oxide precursor. For example, when the precursor coating layer containing the doping element is formed using at least one of the solid phase method, precipitation method, and gel method described above, in the embodiment, at least one of the third mixing process in step S21, the fourth mixing process in step S22, and the fifth mixing process in step S25 further includes the step of adding a lithium nickel manganese oxide precursor to the mixture for mixing.

[0189] In addition, the weight content ratio of the precursor coating layer formed in step S20 in the precursor coating particles or the thickness of the precursor coating layer can be controlled to directly control the content or thickness of the shell layer generated by the fourth sintering treatment in step S30 in the composite lithium nickel manganese oxide, that is, the content or thickness of the shell layer 20 contained in the composite lithium nickel manganese oxide in the above-mentioned embodiment of the application, such as the content or thickness of the first coating layer 21 and the second coating layer 22.

[0190] Step S30:

[0191] During the fourth sintering treatment in step S30, the precursor coating contained in the precursor-coated particles prepared in step S20 is sintered to form a shell layer, specifically the shell layer 20 contained in the composite lithium nickel manganese oxide in the above-mentioned embodiment of the application. When the precursor coating contained in the precursor-coated particles prepared in step S20 does not contain a lithium nickel manganese oxide precursor, then during the fourth sintering treatment, the doping elements such as Te and M contained in the precursor coating directly thermally diffuse and dope the lithium nickel manganese oxide contained in the particle material in step S10, thereby forming a doped coating layer containing doped lithium nickel manganese oxide, which is the first coating layer 21 contained in the shell layer 20 of the composite lithium nickel manganese oxide in the above-mentioned embodiment of the application.

[0192] When the precursor coating layer contained in the precursor coated particles prepared in step S20 contains a lithium nickel manganate precursor, then during the fourth sintering process, the doping elements contained in the precursor coating layer, such as Te and M, directly generate doped lithium nickel manganate with the precursor coating layer containing the lithium nickel manganate precursor. Of course, there may also be thermal diffusion and doping of Te and M elements to the surface of the granular material in step S10 to form doped lithium nickel manganate. At this time, the doped lithium nickel manganate formed on the surface of the granular material in step S10 and the doped lithium nickel manganate formed by the precursor coating layer together form a doped coating layer containing doped lithium nickel manganate. At this time, the doped coating layer is the first coating layer 21 contained in the shell layer 20 of the composite lithium nickel manganate in the above-mentioned embodiment of the application.

[0193] Based on the above explanation of the shell layer of the composite lithium nickel manganese oxide formed after the fourth sintering treatment, the core body contained in the composite lithium nickel manganese oxide formed after the fourth sintering treatment does not contain the above doping elements.

[0194] In addition, during the fourth sintering process, the doping elements contained in the precursor coating layer will directly form a coating layer containing the doping element compound. At this time, the coating layer containing the doping element compound is the second coating layer 22 contained in the shell layer 20 of the composite lithium nickel manganese oxide in the above application embodiment.

[0195] In an embodiment, the fourth sintering process may include the following two-stage sintering process:

[0196] The first stage of sintering treatment: temperature is 500-800℃, time is 6-10h;

[0197] The second stage of sintering treatment: temperature is 200-600℃, time is 3-6h.

[0198] By dividing the fourth sintering process into two stages, the precursor coating layer can be formed into a shell layer, such as the shell layer 20 of the composite lithium nickel manganese oxide in the embodiment of the above application, and the shell layer 20 is formed into a first coating layer 21 and a second coating layer 22. On this basis, the integrity of the shell coating can be improved, and the role of the shell layer 20 of the composite lithium nickel manganese oxide in the embodiment of the above application can be fully exerted, while the efficiency of the fourth sintering process can be improved.

[0199] positive electrode

[0200] In a third aspect, embodiments of the present application provide a positive electrode. The positive electrode of the embodiments of the present application includes a positive electrode current collector and a positive electrode active layer bonded to the positive electrode current collector. The positive electrode active layer contained in the positive electrode of the embodiments of the present application can be bonded to the surface of the current collector. Of course, when the positive electrode current collector has a porous structure, the positive electrode active layer can also be embedded in the positive electrode current collector.

[0201] In the embodiments, the positive electrode of the present application can be a positive electrode sheet, that is, the positive electrode current collector is in the form of a sheet having two opposing surfaces, and the positive electrode active layer is bonded to one or both surfaces of the sheet-shaped positive electrode current collector. Of course, when the sheet-shaped positive electrode current collector has a porous structure, the positive electrode active layer can be further bonded to the porous structure of the sheet-shaped positive electrode current collector.

[0202] The positive electrode active layer contains the composite lithium nickel manganese oxide of the above-mentioned embodiment of the application.

[0203] Because the positive electrode of the present embodiment contains the composite lithium nickel manganese oxide of the present embodiment, the positive electrode of the present embodiment has high capacity and energy density. Furthermore, the positive electrode active layer has a stable interface with the electrolyte, few side reactions, and exhibits electrochemical properties such as high storage and cycling performance, particularly at high temperatures.

[0204] In some embodiments, the positive electrode active layer may include, in addition to the composite lithium nickel manganese oxide, a binder and a conductive agent. The types and contents of the binder and conductive agent are not specifically limited and may be selected and controlled according to actual needs.

[0205] In an exemplary embodiment, the binder may be one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethylcellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives.

[0206] In an exemplary embodiment, the conductive agent may include one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotubes.

[0207] In addition, the type of positive electrode current collector included in the positive electrode of the present invention is not specifically limited and can be selected according to actual needs. The positive electrode current collector is generally a structure or component that can collect current and can be made of various materials suitable for use as positive electrode current collectors in electrochemical energy storage devices. For example, in the exemplary embodiment, the positive electrode current collector can generally be in the form of a sheet, and its material can include but is not limited to metal foil, more specifically, nickel foil and aluminum foil.

[0208] In the embodiment, the positive electrode of the embodiment of the present application can be prepared according to a method including the following steps: mixing composite lithium nickel manganese oxide, a conductive agent and a binder to obtain an electrode slurry, coating the positive electrode slurry on the positive electrode collector, and preparing the positive electrode sheet through steps such as drying, rolling, and die cutting.

[0209] Battery

[0210] In a fourth aspect, an embodiment of the present application provides a battery comprising a positive electrode and a negative electrode, wherein the positive electrode is the positive electrode of the embodiment of the present application.

[0211] Since the positive electrode of the battery of the embodiment of the present application is the positive electrode of the embodiment of the present application, the voltage and energy density of the battery of the embodiment of the present application are high, and the contact interface between the positive electrode and the electrolyte is stable. If the precipitation of Mn at the contact interface between the positive electrode and the electrolyte can be effectively reduced or avoided, 2+ The undesirable phenomena such as ionization and gas production are eliminated, thereby effectively improving the electrochemical properties such as the cycle performance of the battery of the embodiment of the present application, especially the electrochemical properties such as excellent rate performance and cycle performance at high temperature.

[0212] In an embodiment, the battery of the embodiment of the present application may include any one of a battery cell, a battery module, and a battery pack.

[0213] The battery cell refers to a battery housing and an electrode assembly encapsulated in the battery housing. The shape of the battery cell is not particularly limited and can be cylindrical, square or any other shape. In an exemplary embodiment, the battery cell can be Figure 3 The battery cell 30 shown has a square structure.

[0214] In some embodiments, as Figure 4As shown, the outer package of the battery cell 30 can include a housing 31 and a cover plate 33. The housing 31 can include a bottom plate and side plates connected to the bottom plate, which enclose a receiving cavity. The housing 31 has an opening communicating with the receiving cavity, and the cover plate 33 is used to cover the opening to seal the receiving cavity. The positive electrode, the separator and the negative electrode contained in the battery cell 30 of the embodiment can form an electrode assembly 32 through a winding process and / or a stacking process. The electrode assembly 32 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 32. The number of the electrode assembly 32 contained in the battery cell 30 can be one or more, which can be adjusted according to actual needs.

[0215] The preparation method of the battery cell 30 is known. In some embodiments, the positive electrode, the separator and the negative electrode and the electrolyte can be assembled to form the battery cell 30. As an example, the positive electrode, the separator and the negative electrode can be formed into an electrode assembly 32 through a winding process or a stacking process, the electrode assembly 32 is placed in the outer package, the electrolyte is injected after drying, and the battery cell 30 is obtained through processes such as vacuum packaging, standing, formation, shaping, etc.

[0216] The battery module refers to the assembly of the battery cell 30, that is, it can contain a plurality of battery cells 30, and the specific number can be adjusted according to the application and capacity of the battery module.

[0217] In some embodiments, Figure 5 is a schematic view of the battery module 40 as an example. As Figure 5 shown, in the battery module 40, a plurality of battery cells 30 can be arranged in sequence along the length direction of the battery module 40. Of course, it can also be arranged in other arbitrary ways. Further, the plurality of battery cells 30 can be fixed by fasteners.

[0218] Optionally, the battery module 40 can also include a housing having a receiving space, and the plurality of battery cells 30 are received in the receiving space.

[0219] The battery pack refers to the assembly of the battery cell 30 described above, that is, it can contain a plurality of battery cells 30, wherein the plurality of battery cells 30 can be assembled into the battery module 40 described above. The specific number of battery cells 30 or battery modules 40 contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0220] As in the embodiments, Figure 6 and Figure 7 is a schematic view of the battery pack 50 as an example. The battery pack 50 can include a battery box and a plurality of battery modules 40 arranged in the battery box. The battery box includes an upper box body 51 and a lower box body 52, the upper box body 51 is used to cover the lower box body 52 and forms a closed space for receiving the battery module 40. The plurality of battery modules 40 can be arranged in the battery box in any manner.

[0221] Electrical devices

[0222] In a fifth aspect, embodiments of the present application further provide an electrical device comprising the battery of the aforementioned embodiments, which may further comprise a secondary battery. The battery can serve as both a power source and an energy storage unit for the electrical device. Consequently, the electrical device of the embodiments of the present application has a long standby or battery life.

[0223] Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc. These electrical devices may use secondary batteries, battery modules, or battery packs based on their usage requirements.

[0224] Figure 8 The diagram is a schematic diagram of an exemplary electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this device, a battery pack or battery module can be used.

[0225] As another example, the electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a secondary battery as a power source.

[0226] Example

[0227] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0228] 1. Composite lithium nickel manganese oxide and its preparation method embodiment

[0229] Example A1-1

[0230] This embodiment provides a composite lithium nickel manganese oxide and its preparation method. The structure of the composite lithium nickel manganese oxide in this embodiment is as follows: Figure 1 As shown, the core 10 and the shell 20 covering the core 10 are included. The shell 20 includes a first coating layer 21 covering the core 10 and a second coating layer 22 covering the first coating layer 21. The material of the core 10 contains lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4), the D of the nucleus 10 VThe particle size is 5 μm. The weight of the first coating layer 21 is 3% of the weight of the core 10 and is made of lithium nickel manganese oxide doped with Te and W. The weight of the second coating layer 22 is 0.5% of the weight of the core 10 and is made of WTe2. Specific data are shown in Table 1 below.

[0231] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0232] S1. Prepare an aqueous solution of manganese nitrate (denoted as solution A, with a concentration of 0.5 mol / L), an aqueous solution of nickel nitrate (denoted as solution B, with a concentration of 0.5 mol / L), an aqueous solution of tellurium nitrate (denoted as solution C, with a concentration of 0.5 mol / L), and an aqueous solution of tungsten nitrate (denoted as solution D, with a concentration of 0.5 mol / L).

[0233] S2. Preparation of lithium nickel manganese oxide particles:

[0234] S21. A polyacrylamide complexing agent was added to solution A for complexation reaction, and the complexation reaction temperature was controlled to 70°C and the pH value was 9 until a gel-like substance A1 was obtained;

[0235] Adding a polyacrylamide complexing agent to solution B for complexing reaction, and controlling the temperature of the complexing reaction to be 70° C. and the pH value to be 9, until a gel-like substance B1 is obtained;

[0236] S22. The gel-like substance A1 and the gel-like substance B1 were dried and ball-milled with lithium nitrate in a weight ratio of 1.5:0.5:1 to obtain a lithium nickel manganese oxide precursor;

[0237] S23. The lithium nickel manganese oxide precursor is first sintered at 650°C for 8 hours and then sintered at 400°C for 5 hours to produce lithium nickel manganese oxide particles;

[0238] S3. Preparation of Precursor-Coated Particles:

[0239] S31. A polyacrylamide complexing agent was added to the solution C for complexation reaction, and the temperature of the complexation reaction was controlled to 70°C and the pH value was 9 until a gel-like substance C1 was obtained;

[0240] Adding a polyacrylamide complexing agent to the solution D for complexation reaction, and controlling the temperature of the complexation reaction to be 70° C. and the pH value to be 9, until a gel-like substance D1 is obtained;

[0241] S32. The gel-like substance A1, gel-like substance B1, gel-like substance C1, and gel-like substance D1 are dried and ball-milled with the lithium nickel manganese oxide particles in S2 in a weight ratio of 1: (1.5 + 0.47): 0.02: 0.01 to obtain precursor-coated particles;

[0242] S4. The precursor-coated particles prepared in S3 are first sintered at 650° C. for 8 h and then sintered at 400° C. for 5 h to generate a composite lithium nickel manganese oxide material.

[0243] Example A1-2

[0244] This embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. Compared to Example A1-1, the composite lithium nickel manganese oxide in this embodiment differs in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te and Nb elements, and the material of the second coating layer 22 is NbTe2. The data are shown in Table 1 below.

[0245] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0246] The preparation method of Example A1-1 was followed, except that tungsten nitrate was replaced by niobium nitrate. Other steps were the same.

[0247] Examples A1-3

[0248] This embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. Compared to Example A1-1, the composite lithium nickel manganese oxide in this embodiment differs in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te and Mo elements, and the material of the second coating layer 22 is MoTe2. The data are shown in Table 1 below.

[0249] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0250] The preparation was carried out according to the preparation method in Example A1-1, except that tungsten nitrate was replaced by molybdenum nitrate, and the other steps were the same.

[0251] Examples A1-4

[0252] This embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide in this embodiment differs from that in Example A1-1 in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te and Ta elements, and the material of the second coating layer 22 is TaTe2. The data are shown in Table 1 below.

[0253] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0254] The preparation method of Example A1-1 was followed, except that tungsten nitrate was replaced by tantalum nitrate. Other steps were the same.

[0255] Examples A1-5

[0256] The embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide of the embodiment is different from that of the embodiment A1-1 in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te elements and Sb elements; and the material of the second coating layer 22 is TaTe2. The specific data are as follows in Table 1.

[0257] The preparation method of the composite lithium nickel manganese oxide of the embodiment comprises the following steps.

[0258] The preparation method in the embodiment A1-1 is used for preparation, except that antimony nitrate is used to replace tungsten nitrate, and other steps are the same.

[0259] Embodiment A1-6

[0260] The embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide of the embodiment is different from that of the embodiment A1-1 in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te elements and W and Ta elements; the material of the second coating layer 22 is TaTe2 and WTe2; and the molar ratio of Te:W:Ta is 8:2:1. The weight of the first coating layer is 5 wt% of the weight of the core body, and the weight of the second coating layer is 1 wt% of the weight of the core body.

[0261] The preparation method of the composite lithium nickel manganese oxide of the embodiment comprises the following steps.

[0262] The method in the embodiment A1-1 is used for preparation.

[0263] Embodiment A1-7

[0264] The embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide of the embodiment is different from that of the embodiment A1-1 in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te elements and W and Nb elements; the material of the second coating layer 22 is NbTe2 and WTe2; and the molar ratio of Te:W:Sb is 10:3:2. The weight of the first coating layer is 1 wt% of the weight of the core body, and the weight of the second coating layer is 0.2 wt% of the weight of the core body.

[0265] The preparation method of the composite lithium nickel manganese oxide of the embodiment comprises the following steps.

[0266] The method in the embodiment A1-1 is used for preparation.

[0267] Embodiment A2-1

[0268] The embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. The structure of the composite lithium nickel manganese oxide of the embodiment is as shown in Figure 1 The embodiment is different from the embodiment A1-1 in that the D VThe particle size of 50 is 3 μm, and the morphology of the core body 10 and the composite lithium nickel manganese oxide of this embodiment is cubic, as shown in the data in Table 1 below.

[0269] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0270] S1. Preparation of cubic Mn2O3 and preparation of solution C and solution D:

[0271] Soluble manganese salt and sodium carbonate are dissolved in distilled water in a 1:1 ratio to form a stable solution, and the pH of the solution is adjusted to 7.5-9. The solution is heated at 150°C for 10 hours to react, and finally rinsed, impurities removed, evaporated, concentrated, and crystallized to obtain manganese carbonate powder. Finally, the MnCO3 powder is calcined in air at 500°C for 3 hours to obtain cubic Mn2O3.

[0272] According to step S1 in Example A1-1, an aqueous solution of tellurium nitrate (denoted as solution C) and an aqueous solution of tungsten nitrate (denoted as solution D) were prepared;

[0273] S2. Preparation of lithium nickel manganese oxide particles:

[0274] The cubic Mn2O3 prepared in step S1 was fully ground with lithium source and nickel source according to the stoichiometric ratio of Li / Mn / Ni of 1:1.5:0.5, and then sintered at 650℃ for 8h and then at 400℃ for 5h to generate LiNi 0.5 Mn 1.5 O4 lithium nickel manganese oxide particles;

[0275] S3. Preparation of Precursor-Coated Particles:

[0276] S31. A polyacrylamide complexing agent was added to the solution C for complexation reaction, and the temperature of the complexation reaction was controlled to 70°C and the pH value was 9 until a gel-like substance C1 was obtained;

[0277] Adding a polyacrylamide complexing agent to the solution D for complexation reaction, and controlling the temperature of the complexation reaction to be 70° C. and the pH value to be 9, until a gel-like substance D1 is obtained;

[0278] S32. The gel-like shell precursor formed by the gel-like substance C1 and the gel-like substance D1 is dried and ball-milled with the lithium nickel manganese oxide particles in S2 at a weight ratio of 1:9 to obtain precursor-coated particles;

[0279] S4. The precursor-coated particles prepared in S3 are first sintered at 650° C. for 8 h and then sintered at 400° C. for 5 h to generate a composite lithium nickel manganese oxide material.

[0280] Example A2-2

[0281] This embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide in this embodiment differs from that in Example A2-1 in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te and Nb elements, and the material of the second coating layer 22 is NbTe2. The details are shown in Table 1 below.

[0282] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0283] The preparation was carried out according to the preparation method in Example A2-1, except that tungsten nitrate was replaced by nickel nitrate, and the other steps were the same.

[0284] Example A2-3

[0285] This embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. Compared to Example A2-1, the composite lithium nickel manganese oxide in this embodiment differs in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te and Mo elements, and the material of the second coating layer 22 is MoTe2. The details are shown in Table 1 below.

[0286] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0287] The preparation was carried out according to the preparation method in Example A2-1, except that tungsten nitrate was replaced by nickel nitrate, and the other steps were the same.

[0288] Example A2-4

[0289] This embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. Compared to Example A2-1, the composite lithium nickel manganese oxide in this embodiment differs in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te and Ta elements, and the material of the second coating layer 22 is TaTe2. For details, see the data in Table 1 below.

[0290] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0291] The preparation was carried out according to the preparation method in Example A2-1, except that tungsten nitrate was replaced by nickel nitrate, and the other steps were the same.

[0292] Example A2-5

[0293] This embodiment provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide in this embodiment differs from that in Example A2-1 in that the material of the first coating layer 21 is lithium nickel manganese oxide doped with Te and Sb elements, and the material of the second coating layer 22 is SbTe2. The data are shown in Table 1 below.

[0294] The preparation method of composite lithium nickel manganese oxide in this embodiment includes the following steps:

[0295] Prepared according to the preparation method in Example A2-1, except that tungsten nitrate was replaced by nickel nitrate, and other steps were the same.

[0296] Comparative Example A1-1

[0297] This comparative example provides a lithium nickel manganese oxide and a preparation method thereof. The lithium nickel manganese oxide of this comparative example does not contain a shell layer compared with Example A1-1. The specific data are as follows in Table 1 below.

[0298] The preparation method of the lithium nickel manganese oxide of this comparative example comprises the following steps:

[0299] S1. Prepare an aqueous solution of manganese nitrate (denoted as solution A, the concentration of the solution is 0.5 mol / L), an aqueous solution of nickel nitrate (denoted as solution B, the concentration of the solution is 0.5 mol / L), respectively;

[0300] S2. Preparation of lithium nickel manganese oxide particles: as in step S2 in Example A1-1.

[0301] Comparative Example A1-2

[0302] This comparative example provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide of this comparative example is different from Example A1-1 in that the shell layer only contains a first coating layer, and the first coating layer material is A1 element-doped lithium nickel manganese oxide. That is, the shell layer is only an A1 element-doped lithium nickel manganese oxide coating layer, and does not contain the second coating layer in Example A1-1. The specific data are as follows in Table 1 below.

[0303] The preparation method of the composite lithium nickel manganese oxide of this comparative example comprises the following steps:

[0304] S1. Prepare an aqueous solution of manganese nitrate (denoted as solution A, the concentration of the solution is 0.5 mol / L), an aqueous solution of nickel nitrate (denoted as solution B, the concentration of the solution is 0.5 mol / L), an aqueous solution of aluminum nitrate (denoted as solution E, the concentration of the solution is 0.5 mol / L), respectively;

[0305] S2. Preparation of lithium nickel manganese oxide particles: as in step S2 in Example A1-1;

[0306] S3. Preparation of precursor-coated particles:

[0307] S31. Add a polyacrylamide complexing agent to solution E to perform a complexing reaction, and control the temperature of the complexing reaction to be 70°C and the pH value to be 9, until a gel-like substance E1 is obtained;

[0308] S32. Dry the gel-like substance A1, the gel-like substance B1, and the gel-like substance E1, and then perform ball milling treatment with the lithium nickel manganese oxide particles in S2 according to a weight ratio of 1:(1.5+0.47):0.03, to obtain precursor-coated particles;

[0309] S4. The precursor-coated particles prepared in S3 are first sintered at 650° C. for 8 h and then sintered at 400° C. for 5 h to generate a composite lithium nickel manganese oxide material.

[0310] Comparative Example A1-3

[0311] This comparative example provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide in this comparative example differs from Example A1-1 in that the shell comprises only a first coating layer, and this first coating layer is made of tungsten-doped lithium nickel manganese oxide. In other words, the shell comprises only a tungsten-doped lithium nickel manganese oxide coating layer and does not contain the second coating layer of Example A1-1. The data are shown in Table 1 below.

[0312] The preparation method of the composite lithium nickel manganese oxide of this comparative example comprises the following steps:

[0313] S1. Prepare an aqueous solution of manganese nitrate (denoted as solution A, with a concentration of 0.5 mol / L), an aqueous solution of nickel nitrate (denoted as solution B, with a concentration of 0.5 mol / L), and an aqueous solution of tungsten nitrate (denoted as solution D, with a concentration of 0.5 mol / L).

[0314] S2. Preparation of lithium nickel manganese oxide particles: as in step S2 of Example A1-1;

[0315] S3. Preparation of Precursor-Coated Particles:

[0316] S31. A polyacrylamide complexing agent was added to the solution D for complexation reaction, and the temperature of the complexation reaction was controlled to 70°C and the pH value was 9 until a gel-like substance D1 was obtained;

[0317] S32. The gel-like substance A1, the gel-like substance B1, and the gel-like substance D1 are dried and ball-milled with the lithium nickel manganese oxide particles in S2 at a weight ratio of 1: (1.5 + 0.47): 0.03 to obtain precursor-coated particles;

[0318] S4. The precursor-coated particles prepared in S3 are first sintered at 650° C. for 8 h and then sintered at 400° C. for 5 h to generate a composite lithium nickel manganese oxide material.

[0319] Comparative Examples A1-4

[0320] This comparative example provides a composite lithium nickel manganese oxide and a preparation method thereof. The composite lithium nickel manganese oxide in this comparative example differs from Example A1-1 in that the shell comprises only a first coating layer, and the first coating layer is made of Te-doped lithium nickel manganese oxide. In other words, the shell comprises only a Te-doped lithium nickel manganese oxide coating layer and does not contain the second coating layer of Example A1-1. The data are shown in Table 1 below.

[0321] The preparation method of the composite lithium nickel manganese oxide of this comparative example comprises the following steps:

[0322] S1. Prepare an aqueous solution of manganese nitrate (denoted as solution A, 0.5 mol / L), an aqueous solution of nickel nitrate (denoted as solution B, 0.5 mol / L), and an aqueous solution of tellurium nitrate (denoted as solution C, the concentration of the solution is 0.5 mol / L);

[0323] S2. Preparation of lithium nickel manganese oxide particles: as in step S2 of Example A1-1;

[0324] S3. Preparation of Precursor-Coated Particles:

[0325] S31. A polyacrylamide complexing agent was added to the solution C for complexation reaction, and the temperature of the complexation reaction was controlled to 70°C and the pH value was 9 until a gel-like substance C1 was obtained;

[0326] S32. The gel-like substance A1, the gel-like substance B1, and the gel-like substance C1 were dried and ball-milled with the lithium nickel manganese oxide particles in S2 in a weight ratio of 1: (1.5 + 0.47): 0.03 to obtain precursor-coated particles;

[0327] S4. The precursor-coated particles prepared in S3 are first sintered at 650° C. for 8 h and then sintered at 400° C. for 5 h to generate a composite lithium nickel manganese oxide material.

[0328] Comparative Example A1-5

[0329] This comparative example provides a composite lithium nickel manganese oxide and a preparation method thereof. Compared to Example A1-1, the composite lithium nickel manganese oxide in this comparative example differs in that the Te element in the shell is replaced with the S element. Specifically, the first coating layer contained in the shell is lithium nickel manganese oxide doped with S and W elements, and the second coating layer is made of WS2. The data are shown in Table 1 below.

[0330] The preparation method of the composite lithium nickel manganese oxide of this comparative example comprises the following steps:

[0331] S1. Prepare an aqueous solution of manganese nitrate (denoted as solution A, 0.5 mol / L), an aqueous solution of nickel nitrate (denoted as solution B, 0.5 mol / L), and ammonium sulfate respectively;

[0332] S2. Preparation of lithium nickel manganese oxide particles: as in step S2 of Example A1-1;

[0333] S3. Preparation of Precursor-Coated Particles:

[0334] S31. Adding polyacrylamide complexing agent to solution D to perform complexation reaction, and controlling the temperature of the complexation reaction to be 70°C and the pH value to be 9 until a gel-like substance D1 is obtained;

[0335] S32. After drying the gel-like substance A1, the gel-like substance B1, and the gel-like substance D1, ball milling is performed with ammonium sulfate and nickel-manganese acid lithium particles in S2 in a certain proportion to obtain precursor coated particles.

[0336] S4. The precursor coated particles prepared in S3 are sintered at 650°C for 8h first, and then sintered at 400°C for 5h to form a composite nickel-manganese acid lithium material.

[0337] Comparative Example A2-1

[0338] This comparative example provides a nickel-manganese acid lithium and a preparation method thereof. The nickel-manganese acid lithium of this comparative example does not contain a shell layer compared with Example A2-1. The specific data are as follows in Table 1 below.

[0339] The preparation method of the nickel-manganese acid lithium of this comparative example includes the following steps:

[0340] S1. Cubic Mn2O3 is prepared according to the preparation method of cubic Mn2O3 in step S1 of Example A2-1.

[0341] S2. Preparation of nickel-manganese acid lithium particles: as in step S2 of Example A2-1.

[0342] The volume distribution particle size Dv50 in Table 1 is determined by a particle size analyzer-laser diffraction method. Specifically, it can be measured according to the manufacturer's instructions by using a laser diffraction scattering particle size analyzer (Mastersizer3000 laser particle size analyzer) according to the standard GB / T 19077-2016.

[0343] Table 1

[0344]

[0345]

[0346] 2. Secondary battery cell examples

[0347] Examples B1-1 to B2-5 and Comparative Examples B1-1 to B2-1;

[0348] Examples B1-1 to B2-5 and Comparative Examples B1-1 to B2-1 respectively provide a secondary battery cell, each of which includes an electrode assembly formed by a positive electrode, a separator, and a negative electrode, and further includes an electrolyte.

[0349] The positive electrode is prepared according to the following method:

[0350] Using methylpyrrolidone (NMP) as a solvent, the composite lithium nickel manganese oxide provided in Examples A1-1 to A2-5 and the lithium nickel manganese oxide provided in Comparative Examples A1-1 to A2-1 as positive electrode active materials were respectively mixed with a conductive agent carbon nanotube (CNT) and a binder (PVDF) in a mass ratio of 8:1:1 to prepare a positive electrode slurry; the positive electrode slurry was evenly coated on an aluminum foil, double-sided coating was performed, and a positive electrode was obtained after sufficient drying, cold pressing, and slitting; wherein the composite lithium nickel manganese oxide provided in Example A1-1 was used as the positive electrode active material of the positive electrode sheet in Example B1-1, the composite lithium nickel manganese oxide provided in Example A1-2 was used as the positive electrode active material of the positive electrode sheet in Example B1-2, and so on. The lithium nickel manganese oxide provided in Comparative Example A2-1 was used as the positive electrode active material of the positive electrode sheet in Comparative Example B2-1;

[0351] Negative electrode: metallic lithium;

[0352] Electrolyte: LiPF6-EC / DEC.

[0353] Secondary battery assembly: Under vacuum drying; in an argon atmosphere glove box, the positive electrode and negative electrode prepared above were stacked in the order of "positive electrode-separator-negative electrode", and then filled with electrolyte, and assembled into button batteries, respectively recorded as Example B1-1 to Example B2-5 and Comparative Example B1-1 to Comparative Example B2-1.

[0354] 3. Performance test of composite lithium nickel manganese oxide and secondary battery cells

[0355] The composite lithium nickel manganese oxide and the secondary battery cells provided in the above embodiments and comparative examples were tested respectively.

[0356] 3.1 Composite lithium nickel manganese oxide performance test:

[0357] The composite lithium nickel manganese oxide provided in Examples A1-1 to A2-5 and the lithium nickel manganese oxide provided in Comparative Examples A1-1 to A2-1 were analyzed by scanning electron microscopy (SEM), and the results were as follows: Figure 10 Among them, the SEM picture in Example A1-1 is as shown Figure 10 As shown in Figure a, the SEM image in Example A2-1 is as shown in Figure a. Figure 10 As shown in Figure b, the SEM image in Comparative Example A1-1 is as shown in Figure Figure 10 As shown in Figure c, the SEM image in Comparative Example A1-2 is as shown in Figure c. Figure 10 As shown in Figure d, the SEM images in Comparative Example A1-3 are as shown in Figure d. Figure 10 As shown in Figure e, the SEM images in Comparative Example A1-4 are as shown in Figure e. Figure 10 As shown in Figure f.

[0358] Further SEM analysis was performed on the composite lithium nickel manganese oxide provided in Examples A1-2 to A1-7 and Examples A2-2 to A2-5, respectively. The SEM images of the composite lithium nickel manganese oxide provided in Examples A1-2 to A1-7 were similar to those in Figure 10 Similar to Figure a in Example A2-2 to Example A2-5, the SEM images of the composite lithium nickel manganese oxide provided are similar to Figure 10 Similar to Figure b in .

[0359] Depend on Figure 10 As shown, the composite lithium nickel manganese oxide provided in this embodiment has relatively large crystal faces, especially the crystals of the composite lithium nickel manganese oxide provided in Examples A2-1 and A2-2 present a cubic structure, and the crystal face (100) accounts for more than 80%.

[0360] 3.2 Secondary battery cell performance test:

[0361] 3.2.1 Secondary battery cell electrochemical performance test:

[0362] The secondary battery cells in the above-mentioned Examples B1-1 to B2-5 and Comparative Examples B1-1 to B2-1 were subjected to the relevant electrochemical performance tests shown in Table 2 below. The test conditions were: test temperature of 45°C, charge and discharge rate of 1C, and discharge cut-off voltage of 3.5V~4.9V (vs.Li+ / Li).

[0363] The test results are shown in Table 2 and Figure 11 shown.

[0364] Table 2

[0365]

[0366] 3.2.2 Test of manganese precipitation after secondary battery cell cycle:

[0367] After the secondary battery cells in the above-mentioned Examples B1-1 to B2-5 and Comparative Examples B1-1 to B2-1 were cycled at 45°C and 1C for 40 cycles, the Mn content in the negative electrode of each battery cell was tested using an inductively coupled plasma emission spectrometer (ICP). The test results of the Mn content in the negative electrode ICP of each secondary battery cell are shown in Table 3 below:

[0368] Table 3

[0369] Implementation Plan Test Elements Dissolution amount (ppm) Example B1-1 Mn 700 Example B1-2 Mn 800 Example B1-3 Mn 850 Example B1-4 Mn 750 Example B1-5 Mn 800 Example B2-1 Mn 600 Example B2-2 Mn 700 Example B2-3 Mn 650 Example B2-4 Mn 800 Example B2-5 Mn 750 Comparative Example B1-1 Mn 1800 Comparative Example B1-2 Mn 1200 Comparative Example B1-3 Mn 1500 Comparative Example B1-5 Mn 1000 Comparative Example B2-1 Mn 2400

[0370] From Tables 2 and 3 and the attached Figure 11As can be seen, compared to the comparative example, the cycle performance of the secondary battery cells provided by this embodiment is significantly improved, and the amount of manganese precipitation is significantly reduced. Specifically, after testing, the shell layers of Examples A1-6 and A1-7 are doped with multiple doping elements, and the corresponding batteries of Examples B1-6 and B1-7 have better cycle performance and manganese precipitation inhibition than the batteries of Examples B1-1, B1-2, B1-4, and B1-5.

[0371] It can be seen from this that the composite lithium nickel manganese oxide material provided in this embodiment has good interface stability through its double-layer shell coating and doping, and the selection and doping control of the doping elements, which reduces the occurrence of side reactions between the electrode / electrolyte at the interface, while ensuring the lithium ion transmission efficiency, and has good initial charge and discharge efficiency and higher discharge specific capacity; at the same time, the structural stability of the material is high, which inhibits the dissolution of crystalline manganese and improves the cycle stability of the material.

[0372] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A composite lithium nickel manganese oxide, characterized in that: It has a core-shell structure, and the shell layer of the core-shell structure includes a first coating layer and a second coating layer, the first coating layer covers the core of the core-shell structure, and the second coating layer covers the first coating layer; wherein the material of the core includes lithium nickel manganese oxide; the material of the first coating layer includes doped lithium nickel manganese oxide, the doping elements contained in the doped lithium nickel manganese oxide include Te element and M element, and the M element includes at least one of transition metal elements and VA group metal elements; the material of the second coating layer includes a doping element compound formed by the doping element.

2. The composite lithium nickel manganese oxide according to claim 1, characterized in that: The doping element compound includes MTe; and / or The doping content of the doping element in the shell layer is 1000ppm-10000ppm.

3. The composite lithium nickel manganese oxide according to claim 1 or 2, characterized in that: The transition metal element includes at least one of Nb, Mo, Ta, and W; and / or The VA group metal element includes Sb; and / or The doping molar ratio of the Te element to the M element is 1-10:0.5-5, and the doping amount of the Te element is higher than the doping amount of the M element.

4. The composite lithium nickel manganese oxide according to claim 1 or 2, characterized in that: The doping element compound includes at least one of NbTe2, MoTe2, TaTe2, WTe2, and SbTe2; and / or The doped lithium nickel manganese oxide includes LiTe x Nb y Ni 0.5-x-y Mn 1.5-x-y O4、LiTe x Nb y Ni 0.5-x-y Mn 1.5-x-y O4、LiTe x W y Ni 0.5-x-y Mn 1.5-x-y O4 or LiTe x Ta y Ni 0.5-x-y Mn 1.5-x-y At least one of O4; wherein, x=0.01-0.1, y=0.005-0.

05.

5. The composite lithium nickel manganese oxide according to claim 1 or 2, characterized in that: From the second cladding layer to the core body, the content of the doping element in the first cladding layer gradually decreases.

6. The composite lithium nickel manganese oxide according to claim 1 or 2, characterized in that: The Dv50 particle size of the core body is 3 μm-15 μm; and / or The shell satisfies any of the following conditions: The weight of the first coating layer is 0.5wt%-5wt% of the weight of the core body; The weight of the second coating layer is 0.2wt%-1wt% of the weight of the core body; The thickness of the first coating layer is 50nm-200nm; The thickness of the second coating layer is 10 nm-100 nm.

7. The composite lithium nickel manganese oxide according to claim 1 or 2, characterized in that: The core and the composite lithium nickel manganese oxide are independently of each other in a cubic crystal form; and / or The Dv50 particle size of the composite lithium nickel manganese oxide is 4 μm-18 μm.

8. A method for preparing composite lithium nickel manganese oxide, comprising the following steps: Providing granular materials containing lithium nickel manganese oxide; forming a precursor coating layer containing doping elements on the surface of the particle material to form precursor-coated particles; sintering the precursor coated particles so that the precursor coating layer forms a shell layer coating the nickel-containing lithium manganese oxide particles; in, The shell layer includes a first coating layer coating the lithium nickel manganese oxide particles and a second coating layer coating the first coating layer; the material of the first coating layer includes lithium nickel manganese oxide doped with the doping element, and the material of the second coating layer includes a doping element compound formed by the doping element; the doping element includes Te and M, and the M element includes at least one of a transition metal element and a Group VA metal element.

9. The preparation method according to claim 8, characterized in that: The content of the doping element in the precursor coating layer satisfies: the doping content of the doping element in the shell layer is 1000ppm-10000ppm; and / or The sintering process includes the following two stages of sintering: The first stage of sintering treatment: temperature is 500-800℃, time is 6-10h; The second stage of sintering treatment: temperature is 200-600℃, time is 3-6h.

10. The preparation method according to claim 8 or 9, characterized in that: The crystal form of the granular material is a regular cube; and / or The granular material is prepared by a method comprising: The manganese source is sintered in air to obtain Mn2O3; Mixing the Mn2O3 with a lithium source and a nickel source in proportion to obtain a nickel-containing lithium manganate precursor; The nickel-containing lithium manganese oxide precursor is sintered to obtain the nickel-containing lithium manganese oxide particle material.

11. The preparation method according to claim 10, characterized in that: The temperature of the manganese source during the sintering treatment in air is 600-800° C.; and / or The temperature of the sintering treatment of the nickel-containing lithium manganese oxide precursor is 200-800°C.

12. A positive electrode comprising a positive electrode active layer, characterized in that: The positive electrode active material contained in the positive electrode active layer includes the composite lithium nickel manganese oxide according to any one of claims 1 to 7 or the composite lithium nickel manganese oxide prepared by the preparation method according to any one of claims 8 to 11.

13. A battery comprising a positive electrode, characterized in that: The positive electrode is the positive electrode according to claim 12.

14. An electrical device, characterized in that: The electrical device comprises the battery according to claim 13, and the battery is used to provide electrical energy.

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