Multifunctional layer lithium manganate positive electrode material, preparation method thereof and lithium battery

Abstract

The application belongs to the technical field of energy materials, and provides a multifunctional layer lithium manganate positive electrode material, a preparation method thereof and a lithium battery. 1+a Mn 2‑b‑c‑d M b R c X d O 4‑e Z e The body-phase doping elements of the matrix are M and Z, the crystal face inducing elements are X, and the modifying doping elements are R; the coating layer is a compound comprising coating elements M'; a supported crystal face inducing agent is also used to further inhibit the growth of the (111) crystal face, and the area of the (111) crystal face is reduced, so as to form a positive electrode material comprising a multi-faceted spinel crystal structure of at least 26 crystal faces, the crystal face inducing agent comprises a phosphorus-containing compound, a boron-containing compound or a metal salt with at least a +5 valence state; the Mn elution reaction is reduced, and the lithium manganate electrochemical performance is improved.

Description

Technical Field

[0001] This application belongs to the field of energy materials technology, and in particular relates to a multifunctional layered lithium manganese oxide cathode material, its preparation method, and a lithium battery. Background Technology

[0002] Currently, mainstream lithium-ion battery cathode materials include lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and lithium nickel cobalt manganese oxide. Among them, lithium manganese oxide (LiMn2O4) has become a promising lithium-ion cathode material due to its advantages such as low cost, high rate capability, and high safety. However, lithium manganese oxide faces serious challenges during cycling, including the Jahn-Teller effect, manganese dissolution, and irreversible phase transition. To overcome these problems, various strategies have been adopted, such as bulk doping and surface coating. Doping elements such as Ni, Co, Ti, Zr, Mg, Al, F, B, and S can improve the structural stability and performance of lithium manganese oxide, but the problem of Mn dissolution caused by electrolyte corrosion at high temperatures has not been fundamentally solved. To improve the high-temperature cycling performance of lithium manganese oxide, surface coating strategies are often used to avoid direct contact between the electrolyte and the active material, thereby slowing down the corrosion of the cathode material and Mn dissolution at high temperatures, and improving the high-temperature performance of lithium manganese oxide. However, these coating materials are not conducive to electron and Li + The transport dynamics of lithium manganese oxide are such that lattice strain occurs during cycling, leading to phase separation and thus reducing the capacity retention rate of the battery. Therefore, a single improvement measure cannot fundamentally solve the existing problems of lithium manganese oxide.

[0003] Existing lithium manganese oxide cathode materials suffer from Mn dissolution due to electrolyte corrosion, and cannot simultaneously improve crystal structure stability and electrochemical performance. Summary of the Invention

[0004] This application provides a multifunctional layered lithium manganese oxide cathode material, its preparation method, and a lithium battery, aiming to solve to some extent the problems of Mn dissolution caused by electrolyte corrosion in lithium manganese oxide cathode materials, and the inability to simultaneously improve crystal structure stability and electrochemical performance.

[0005] In a first aspect, this application provides a multifunctional lithium manganese oxide cathode material, comprising a core and a coating layer covering the surface of the core. Based on the mass content distribution of doping elements in the core, the core is divided from the inside out into a bulk-doped lithium manganese oxide matrix, an induced doping layer, and a modifying doping layer. The general chemical formula of the core is Li. 1+a Mn 2-b-c-d M b R c X d O 4-e Z eIn this compound, M, Z, X, and R are all doping elements. The bulk doping elements of lithium manganese oxide are M and Z, the crystal plane inducing element of the induced doping layer is X, and the modifying doping element of the modified doping layer is R. The inequalities are -0.1≤a≤0.3, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.3, and 0≤e≤0.3, with at least one of b, c, d, and e being non-zero. The coating layer is a compound including the coating element M'.

[0006] The preparation method of multifunctional layered lithium manganese oxide cathode material also uses a supported crystal facet inducer to further suppress the growth of the (111) crystal facet in the spinel crystal structure of lithium manganese oxide and reduce the area of ​​the (111) crystal facet to form a multifunctional layered lithium manganese oxide cathode material with a multifaceted spinel crystal structure including at least 26 crystal faces. The supported crystal facet inducer includes phosphorus-containing compounds, boron-containing compounds or metal salts with at least +5 valence.

[0007] Secondly, this application provides a method for preparing a multifunctional lithium manganese oxide cathode material, used to prepare the multifunctional lithium manganese oxide cathode material as described in any one of the first aspects, comprising:

[0008] S10. The manganese-containing compound is mixed into a dopant containing element M and a supported crystal plane inducer through a doping process. The uniformly mixed manganese-containing mixture is pretreated to obtain a manganese-containing crystal plane inducer precursor.

[0009] S11. After mixing the manganese crystal plane-inducing precursor with dopants containing R, X, and Z elements and lithium salt, a first sintering is performed to obtain a lithium manganese oxide core.

[0010] S12. The lithium manganese oxide core is coated with a coating material containing M' element, and a second sintering is performed to obtain a multifunctional layered lithium manganese oxide cathode material.

[0011] In another embodiment, based on the mass content distribution of doping elements in the core, the modified doped layer includes a doping modification layer and a molten metal oxide layer; the general chemical formula of the lithium manganese oxide matrix is ​​Li. 1+y Mn 2-x J x O4, where 0≤y<0.1, 0≤x<2, and J is the matrix dopant ion;

[0012] The general chemical formula of the modified doped layer is Li f Mn g K' h O2, where 0≤f<1, 0≤g<1, 0≤h<1, and K' is a modified dopant ion.

[0013] In another embodiment, the preparation of the multifunctional layered lithium manganese oxide cathode material as described in any other embodiment includes:

[0014] S20. Dissolve soluble manganese salt, soluble compound containing J element and supported crystal facet inducer in water to obtain mixed metal ion solution;

[0015] S21. Gas is introduced into the mixed metal ion solution, pH is adjusted to the specified value by adding pH adjuster, the reaction is heated and stirred, and after the reaction is completed, the solution is aged, washed, filtered and dried to obtain the manganese crystal facet-induced precursor.

[0016] S22. The lithium source is mixed with the manganese crystal plane-induced precursor, a dopant containing K' element is added, and the mixture is ground, mixed, calcined for the first time, and cooled to obtain the lithium manganese oxide core.

[0017] S23. The lithium manganese oxide core is coated with a coating material containing M' element, and then calcined a second time to obtain a multifunctional layered lithium manganese oxide cathode material.

[0018] The primary particles of the multifunctional layered manganese phosphate cathode material have a near-spherical morphology, and the thickness of the modified doped layer is 8 nm to 200 nm.

[0019] Thirdly, this application provides a lithium battery, including a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a multifunctional lithium manganese oxide positive electrode material as described in any of the first aspects, or a multifunctional lithium manganese oxide positive electrode material as described in any of the other embodiments, or a multifunctional lithium manganese oxide positive electrode material obtained by the preparation method of the multifunctional lithium manganese oxide positive electrode material as described in any of the first aspects, or a multifunctional lithium manganese oxide positive electrode material obtained by the preparation method of the multifunctional lithium manganese oxide positive electrode material as described in any of the other embodiments.

[0020] The advantages of this application compared to the prior art are:

[0021] This application provides a multifunctional lithium manganese oxide cathode material, comprising a core and a coating layer covering the surface of the core. Based on the mass content distribution of doping elements in the core, the core is divided from the inside out into a bulk-doped lithium manganese oxide matrix, an induced doping layer, and a modifying doping layer. The chemical formula of the core is Li. 1+a Mn 2-b-c-d M b R c X d O 4-e Z eIn this material, M, Z, X, and R are all doping elements. The bulk doping elements of lithium manganese oxide are M and Z, the crystal plane inducing element of the induced doping layer is X, and the modifying doping element of the modified doping layer is R. The inequality is -0.1≤a≤0.3, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.3, 0≤e≤0.3, and at least one of b, c, d, and e is not 0. The coating layer is a compound including the coating element M'. The preparation method of the multifunctional layer lithium manganese oxide cathode material also uses a supported crystal plane inducing agent to further suppress the growth of the (111) crystal plane in the spinel crystal structure of lithium manganese oxide and reduce the area of ​​the (111) crystal plane to form a multifunctional layer lithium manganese oxide cathode material with a multifaceted spinel crystal structure including at least 26 crystal planes. The inducing agent includes phosphorus-containing compounds, boron-containing compounds, or metal salts with at least +5 valence states. By employing crystal-inducing elements and supported crystal-inducing agents, and simultaneously altering the growth orientation of the crystal faces through doping of the crystal-inducing elements and the crystal-inducing agents, the primary particles of lithium manganese oxide are modified by crystal-inducing modification. This reduces the exposed area of ​​the (111) crystal face, decreases the Mn dissolution reaction, and suppresses the irreversible phase transition during the cycling process of lithium manganese oxide. Simultaneously, it transforms the traditional octahedral spinel morphology of lithium manganese oxide into a truncated octahedral morphology with at least 26 crystal faces, making the lithium manganese oxide cathode material particles more rounded, reducing the surface energy of the lithium manganese oxide cathode material particles, improving the modification effect of the coating layer, enhancing the stability of the cathode material crystal structure, and increasing the Li... + The diffusion speed and expansion of Li + This improves the electrochemical performance of lithium manganese oxide by optimizing the conduction pathway. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the lithium manganese oxide cathode material of Example 7, which includes a truncated octahedral crystal structure model with at least 26 faces.

[0024] Figure 2 A schematic diagram of the octahedral crystal structure model of existing lithium manganese oxide cathode materials;

[0025] Figure 3 This is a schematic diagram of the first space, second space, and third space from the surface to the interior of a multifunctional layered lithium manganese oxide cathode material.

[0026] Figure 4This is a schematic flowchart illustrating a method for preparing a multifunctional layered lithium manganese oxide cathode material according to an embodiment of this application.

[0027] Figure 5 This is a schematic flowchart illustrating a method for preparing a multifunctional layered lithium manganese oxide cathode material according to another embodiment of this application.

[0028] Figure 6 This is a schematic diagram of the multifunctional layer based on the mass content distribution of each element in the lithium manganese oxide cathode material of Example 1.

[0029] Figure 7 This is a cross-sectional SEM image of the lithium manganese oxide cathode material from Example 7;

[0030] Figure 8 This is a schematic diagram of the elemental distribution of Mn in the lithium manganese oxide cathode material of Example 7;

[0031] Figure 9 This is a schematic diagram of the elemental distribution of Ni in the bulk phase of the lithium manganese oxide cathode material in Example 7;

[0032] Figure 10 This is a schematic diagram of the elemental distribution of bulk F doping in the lithium manganese oxide cathode material of Example 7;

[0033] Figure 11 This is a schematic diagram of the elemental distribution of Ti, the crystal plane induction element, in the lithium manganese oxide cathode material of Example 7;

[0034] Figure 12 This is a schematic diagram of the elemental distribution of the modification and doping element W in the lithium manganese oxide cathode material of Example 7;

[0035] Figure 13 This is a schematic diagram of the elemental distribution of Al, the coating element of the lithium manganese oxide cathode material in this embodiment;

[0036] Figure 14 This is a schematic diagram of the Mn valence state analysis on the XPS surface of existing lithium manganese oxide cathode materials;

[0037] Figure 15 This is a schematic diagram of the Mn valence state analysis on the XPS surface of the lithium manganese oxide cathode material in Example 7;

[0038] Figure 16 This is a magnified SEM image of lithium manganese oxide cathode material particles from existing technology.

[0039] Figure 17 This is a magnified SEM image of the lithium manganese oxide cathode material particles from Example 7.

[0040] Figure 18 This is a SEM image of the octahedral morphology of existing lithium manganese oxide cathode materials.

[0041] Figure 19 This is a SEM image of an octahedral morphology coating layer for existing lithium manganese oxide cathode materials.

[0042] Figure 20 This is a magnified SEM image of broken particles in the octahedral morphology coating layer of existing lithium manganese oxide cathode materials.

[0043] Figure 21 This is a schematic SEM image of the overall truncated octahedral morphology of the lithium oxide cathode material in Example 7.

[0044] Figure 22 This is a SEM image of the lithium oxide cathode material coating layer in Example 7;

[0045] Figure 23 This is a SEM image of the thickness of the lithium oxide cathode material coating layer in Example 7;

[0046] Figure 24 This is a schematic diagram of the linear EDS elemental atomic content of the cross-sectional SEM of the lithium manganese oxide core particles in Example 7.

[0047] Figure 25 This is a magnified schematic diagram of the linear EDS elemental atomic content of the cross-sectional SEM of the lithium manganese oxide core particles in Example 7.

[0048] Figure 26 This is a schematic diagram of the elemental distribution of P in the first supported crystal plane inducer of the lithium manganese oxide core particles in Example 7.

[0049] Figure 27 This is a schematic diagram of the elemental distribution of B in the second supported crystal plane inducer of the lithium manganese oxide core particles in Example 7;

[0050] Figure 28 This is a schematic diagram of the elemental distribution of V in the third-supported crystal plane inducer of the lithium manganese oxide core particles in Example 7.

[0051] Figure 29 A schematic diagram comparing the crystal XRD patterns of the existing octahedral lithium manganese oxide cathode material and the lithium manganese oxide cathode material of Example 7;

[0052] Figure 30 This is a schematic diagram showing the XRD pattern of the lithium manganese oxide cathode material in Example 7 matched with the standard card PDF#70-3120 for lithium manganese oxide.

[0053] Figure 31 This is a schematic diagram comparing the XRD patterns of the lithium manganese oxide cathode materials prepared in Example 1 and Comparative Example 12.

[0054] Figure 32 This is a schematic diagram comparing the cycle count ratio curves of the electrode materials obtained in Example 17 and Comparative Example 12;

[0055] Figure 33 W prepared for Comparative Example 13 6+ Ca 2+ SEM image of the doped lithium manganese oxide cathode material;

[0056] Figure 34 This is a SEM image of the coating layer of the lithium manganese oxide cathode material in Comparative Example 15.

[0057] Figure 35 This is a SEM image of the lithium manganese oxide cathode material particles in Comparative Example 15.

[0058] Figure 36 This is a schematic diagram of the linear EDS elemental atomic content of the cross-sectional SEM of the lithium manganese oxide cathode material particles in Example 17.

[0059] Figure 37 This is a magnified linear EDS schematic diagram of the elemental atomic content of the modified doped layer of the lithium manganese oxide cathode material in Example 17, obtained by cross-sectional SEM. Detailed Implementation

[0060] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0061] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0062] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0063] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application are available on the market or can be prepared by existing methods.

[0064] The technical solution of this application will be described below through specific embodiments.

[0065] In a first aspect, this application provides a multifunctional lithium manganese oxide cathode material, comprising a core and a coating layer covering the surface of the core. Based on the mass content distribution of doping elements in the core, the core is divided from the inside out into a bulk-doped lithium manganese oxide matrix, an induced doping layer, and a modifying doping layer. The general chemical formula of the core is Li.1+a Mn 2-b-c-d M b R c X d O 4-e Z e In this context, M, Z, X, and R are all doping elements. The bulk doping elements of lithium manganese oxide are M and Z, the crystal plane induction element of the induced doping layer is X, and the modification doping element of the modified doping layer is R. The values ​​are -0.1≤a≤0.3, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.3, and 0≤e≤0.3, with at least one of b, c, d, and e being non-zero. The coating layer is a compound containing the coating element M'. The preparation method of the multifunctional layer lithium manganese oxide cathode material also uses a supported crystal plane induction agent to further suppress the growth of the (111) crystal plane in the spinel crystal structure of lithium manganese oxide and reduce the area of ​​the (111) crystal plane to form a multifunctional layer lithium manganese oxide cathode material with a multifaceted spinel crystal structure containing at least 26 crystal planes. The supported crystal plane induction agent includes phosphorus-containing compounds, boron-containing compounds, or metal salts with at least +5 valence states.

[0066] In this embodiment, by employing crystal facet inducing elements and supported crystal facet inducing agents, and by altering the growth orientation of the crystal faces through doping of the crystal facet inducing elements and using crystal facet inducing agents, the primary particles of lithium manganese oxide are modified by crystal facet induction. This reduces the exposed area of ​​the (111) crystal facet, decreases the Mn dissolution reaction, and suppresses the irreversible phase transition during the cycling process of lithium manganese oxide. Simultaneously, it transforms the traditional octahedral spinel morphology of lithium manganese oxide into a truncated octahedral morphology with at least 26 crystal faces, making the lithium manganese oxide cathode material particles more rounded, reducing the surface energy of the lithium manganese oxide cathode material particles, and improving the modification effect of the coating layer. The manganese and oxygen sites of lithium manganese oxide are uniformly doped in the bulk phase, reducing manganese dissolution and improving the stability of the cathode material crystal structure. Then, the modification doping layer and coating layer on the core surface enhance the stability of the interface and improve the Li... + The diffusion speed and expansion of Li + The transport path is improved, and the coating layer forms a physical barrier, reducing electrolyte corrosion and side reactions, thereby improving the electrochemical performance of lithium manganese oxide. In addition, the supported crystal facet inducer, through the molecular coordination blockade of phosphorus-containing compounds, the in-situ sacrificial template coverage of boron-containing compounds, and the secondary doping effect of lattice strain of high-valence metal salts, accurately and uniformly transports the crystal facet inducer to the reaction interface during the key stage of lithium manganese oxide crystal growth. Through corresponding chemical or physical effects, it preferentially inhibits the growth of (111) crystal facets, thereby preparing lithium manganese oxide cathode materials with truncated octahedrons including (400) or (311) crystal facets. Compared with the traditional direct addition method, it improves the dispersion uniformity of the crystal facet inducer and improves the crystal facet induction effect.

[0067] In one embodiment, such as Figure 1 As shown, the crystal faces of the multifaceted spinel crystal structure include: four upper (111) crystal faces, four lower (111) crystal faces, four upper (311) crystal faces spaced apart from each other (111) crystal faces, four lower (311) crystal faces spaced apart from each other (111) crystal faces, four upper and lower (220) or (440) crystal faces that are coplanar, one (004) crystal face at the top, one (004) crystal face at the bottom, and four (400) crystal faces that are coplanar at the corners of the upper and lower parts. The octahedral crystal structure model of existing lithium manganese oxide cathode materials is as follows: Figure 2 As shown.

[0068] In this embodiment, due to the crystal plane inducing element and the supported crystal plane inducing agent, the surface energy of each crystal plane is changed by the doping of the crystal plane inducing element and the crystal plane inducing agent, the growth orientation of the (111) crystal plane is suppressed, and other crystal planes are guided to grow in a directional manner, thereby forming a truncated octahedral morphology, reducing the Mn dissolution reaction and suppressing the phase transition; at the same time, the crystal structure of at least 26 crystal planes makes the particles more rounded, reduces the surface energy of the particles, improves the modification effect of the coating layer, and improves the high temperature cycle performance of the lithium manganese oxide cathode material, that is, improves the cycle life of the lithium battery.

[0069] In one embodiment, such as Figure 3 As shown, bulk dopants are uniformly distributed in the core, crystal plane-inducing elements have an increasing concentration distribution from the inside to the outside of the core, and modifying dopants are located in the modifying doped layer; along the direction from the surface to the inside of the multifunctional lithium manganese oxide cathode material, the first space (space thickness r1) is from 1 / 5 radius r of the average particle size of the multifunctional lithium manganese oxide cathode material to the surface, and the mass ratio ω1 of the sum of the masses of each dopant element and the coating element in the first space to the total mass of each dopant element and the coating element in the multifunctional lithium manganese oxide cathode material is 0.45~0.99:1; along the direction from the surface to the inside of the multifunctional lithium manganese oxide cathode material, the second space (space thickness r1) is from 1 / 2 radius r of the average particle size of the multifunctional lithium manganese oxide cathode material to the surface. The thickness of the first space is r2). In the second space, the mass ratio ω2 of the modified dopant elements to the bulk dopant elements is 1:1 to 20, and the mass ratio ω3 of the crystal plane induction elements to the bulk dopant elements is 1:3 to 6. Along the direction from the surface to the interior of the multifunctional lithium manganese oxide cathode material, from 2 / 3 radius r of the average particle size of the multifunctional lithium manganese oxide cathode material to the surface is the third space (thickness r3). ​​The mass ratio ω4 of the sum of the masses of each dopant element and the coating element in the third space to the total mass of both dopant elements and the coating element in the multifunctional lithium manganese oxide cathode material is 0.90 to 0.99:1. The volume of the third space is larger than the volume of the second space, and the volume of the second space is larger than the volume of the first space. The average particle size of the lithium manganese oxide cathode material is 2 μm to 20 μm.

[0070] In this embodiment, by controlling the concentration of dopants in different spatial regions, the function of each layer is optimized. At the same time, the gradient change of concentration avoids abrupt interface changes and improves structural stability. The total mass ratio of dopants and coating elements in the first space is high, which improves the surface modification effect. The mass ratio of dopants in the second space can balance the stability of surface modification and bulk phase. The total mass ratio of dopants and coating elements in the third space is higher than that in the first space, realizing a smooth transition of element distribution from the inside to the outside and avoiding stress concentration.

[0071] In one embodiment, M is a bulk doping element for manganese sites in the lithium manganese oxide matrix, and M is any one or a combination of Ni, Y, Co, Si, Cu, Zn, Ca, Fe, V, Al, Zr, Mg, La, Cr, Ga, and Ge; Z is a bulk doping element for oxygen sites in the lithium manganese oxide matrix, and Z is any one or a combination of N, F, Cl, Br, I, B, and S; the mass concentration deviation of elements M and Z at any point in the lithium manganese oxide matrix is ​​less than or equal to 20%; X is a crystal plane induction element in the induced doping layer, and X is any one or a combination of Ti, Sn, Nb, Ce, Cu, Ta, V, Mo, Ru, W, Sr, and In; R is a modification doping element for oxygen sites in the modification doping layer, and R is... The coating layer is a combination of one or more of the following: La, Zr, Yb, Ba, Y, Bi, Co, W, Sr, and In; the coating layer is a combination of one or more of the following: oxides, fluorides, phosphates, carbonates, sulfates, nitrates, chlorides, acetates, lithium-ion battery cathode materials, and conductive organic materials containing the coating element M'; M' is a combination of one or more of the following: B, Mg, Nb, Co, Al, Zr, Li, Ti, Ni, In, Mn, Mo, and W; the conductive organic material is a combination of one or more of the following: polyaniline, polyethylene glycol, polypyrrole, poly(3,4-ethylenedioxythiophene), and polystyrene sulfonic acid; the mass ratio of the coating element in the coating layer to the total mass of all doped elements in the core is 1:(0.5–10).

[0072] In this embodiment, the doping and coating elements work synergistically in the lithium manganese oxide cathode material. Bulk doping elements M (such as Ni, Co, Al, etc.) replace manganese sites, improving structural stability and reducing manganese dissolution; bulk doping elements Z (such as F, Cl, P, etc.) replace oxygen sites, enhancing oxygen framework stability; crystal plane inducing elements X (such as Al, Ti, W, etc.) control crystal plane growth and improve lithium-ion mobility; modifying doping elements R (such as La, Y, Zr, etc.) are enriched on the surface, forming a protective layer and inhibiting manganese dissolution; and the coating material including coating elements M' (such as B, Mg, Ti, etc.) forms a dense coating layer on the surface of the lithium manganese oxide core, preventing the electrolyte from directly contacting the lithium manganese oxide core and further preventing side reactions.

[0073] In one embodiment, the coating layer is a lithium-ion battery cathode material with the general chemical formula including Li. 1+i (TM) x PO4 and / or Li 1+i (TM) x Lj, where TM is one or more transition metal elements, 0≤i≤0.3, 0≤x≤2, 1≤j≤5, and L is any combination of one or more of oxygen, an anion of a group 5 main element, an anion of a group 6 main element, or an anion of a group 7 main element; This improves the Li + The diffusion speed and expansion of Li + This improves the electrochemical performance of lithium manganese oxide by optimizing the conduction pathway.

[0074] In one embodiment, the supported material in the supported crystal facet inducer comprises one or more combinations of porous silica nanoparticles, magnesium oxide nanoparticles, or activated carbon nanoparticles. The supported crystal facet inducer comprises a phosphorus-containing compound, a boron-containing compound, or a metal salt with at least a +5 valence state, wherein the metal salt with at least a +5 valence state is a metal salt in which the valence of the metal is greater than or equal to +5. Specifically, the supported crystal facet inducer comprises one or more combinations of phytic acid (PA), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), boric acid (H3BO3), boron oxide (B2O3), or ammonium metavanadate (NH4VO3). For example, the supported crystal facet inducer is one or more combinations of phytic acid / porous silica supported material, 1-hydroxyethylidene-1,1-diphosphonic acid / porous silica supported material, boron oxide / magnesium oxide supported material, or ammonium metavanadate / activated carbon supported material.

[0075] In this embodiment, firstly, the growth of the (111) crystal face is suppressed by introducing a phosphorus-containing organic compound as a crystal face coordination blocking agent. The crystal face inducing agent, phytic acid or HEDP, contains multiple phosphate or phosphonate groups in its molecule, which inhibit the growth of metal ions (such as Mn) 3+It has extremely strong chelating ability. During the crystal growth stage, phosphate or phosphonate groups adsorb onto the (111) crystal plane, which has a high atomic density but is not coordinate-saturated, and form stable coordination bonds with manganese atoms on the surface, thereby inhibiting the growth of the (111) crystal plane. Secondly, the strong adsorption of phosphate or phosphonate groups with metal ions forms a dense molecular barrier on the surface of the (111) crystal plane, which greatly inhibits the growth rate of the (111) plane. Thirdly, during the subsequent sintering process, organic molecules such as phytic acid or HEDP decompose, and the phosphorus element in them is released as trace amounts of P. 5+ P is incorporated into the crystal lattice in the form of doping to achieve secondary bulk doping; 5+ The doping enhances the stability of the crystal structure and synergizes with the previous crystal facet induction effect, thereby improving the electrochemical performance and safety of the lithium manganese oxide cathode material. Using silica as an inert carrier for phosphorus-containing organic matter ensures high dispersion of phytic acid and HEDP molecules, preventing aggregation during subsequent mixing. This allows the phosphorus-containing organic matter to undergo uniform crystal facet induction on the surface of the manganese-containing crystal facet induction precursor, and continuously releases the phosphorus-containing organic matter during crystal growth. This avoids concentrated reaction of the crystal facet inducing agent and improves the uniformity of crystal facet induction.

[0076] Secondly, the growth of the (111) crystal face is suppressed by introducing boron-containing compounds as in-situ sacrificial templates. Boric acid (H3BO3) or boron oxide (B2O3), as crystal face inducing agents, generates an amorphous borate glass phase at high temperatures. This amorphous borate glass phase exists as tiny droplets or thin films, wetting and covering the high surface energy (111) crystal face, forming a physical spatial barrier on the (111) crystal face, thus preventing the (111) crystal face from expanding outwards. This forces the crystal to grow towards crystal faces such as (311) and (400), ultimately forming a truncated octahedral crystal structure. In an alkaline environment, using magnesium oxide as a carrier for boron-containing compounds allows for more stable loading of these compounds. Furthermore, magnesium oxide not only serves as a carrier for dispersing boron-containing compounds, but magnesium ions can also enter the crystal lattice for bulk doping, creating a synergistic stabilizing effect with the template effect of boron, further enhancing the crystal face induction effect and suppressing the growth of the (111) crystal face.

[0077] Third, the growth of the (111) crystal plane is suppressed by introducing a high-valence metal salt as an oxidation-structure reconstruction guide. The vanadium in the crystal plane inducer ammonium metavanadate (NH4VO3) can alter the local lattice structure. 5+ High-valence ions will enter the lithium manganese oxide lattice, causing localized oxidation around the high-valence ions, i.e., Mn around the high-valence ions. 3+ Oxidized to Mn 4+Due to the difference in ionic radii, local lattice distortion and lattice strain are introduced. The lattice strain reduces the surface energy of crystal planes such as (311) and (400), promoting the growth of crystal planes such as (311) and (400). The growth rate of crystal planes such as (311) and (400) is greater than that of crystal plane (111), thereby reducing the proportion of the area of ​​crystal plane (111) in the total crystal area. Since activated carbon has abundant functional groups and a huge specific surface area, it can effectively adsorb and fix vanadate ions. In the formation of the lattice, the rate of release of ammonium metavanadate by activated carbon can be controlled, and more uniform micro-doping and lattice strain induction can be achieved.

[0078] Secondly, such as Figure 4 As shown, this application provides a method for preparing a multifunctional lithium manganese oxide cathode material, used to prepare the multifunctional lithium manganese oxide cathode material as described in any one of the first aspects, comprising:

[0079] S10. The manganese-containing compound is mixed into a dopant containing element M and a supported crystal plane inducer through a doping process. The uniformly mixed manganese-containing mixture is pretreated to obtain a manganese-containing crystal plane inducer precursor.

[0080] S11. After mixing the manganese crystal plane-inducing precursor with dopants containing R, X, and Z elements and lithium salt, a first sintering is performed to obtain a lithium manganese oxide core.

[0081] S12. The lithium manganese oxide core is coated with a coating material containing M' element, and a second sintering is performed to obtain a multifunctional layered lithium manganese oxide cathode material.

[0082] In the preparation method of this embodiment, by utilizing the differences in valence state, atomic radius, and binding energy with oxygen of each element, a multifunctional layer distribution is formed in the lithium manganese oxide bulk after high-temperature sintering. Some elements with small atomic radii easily diffuse into the lithium manganese oxide bulk phase to form a bulk doped structure, while some elements with crystal facet induction function induce the crystal facet growth of lithium manganese oxide, thereby forming a crystal facet induction layer. The modifying dopants, due to their different atomic radii and binding energies with oxygen, mostly remain on the surface of the lithium manganese oxide core, modifying the crystal structure of lithium manganese oxide. After the modification of the above functional layers, lithium manganese oxide will have better electrochemical performance. In addition, the preparation method of this embodiment constructs a carrier-inducer composite crystal facet induction system. The support (such as SiO2, MgO, activated carbon C) ensures the uniform dispersion and site-specific effect of the inducing agents (such as phytic acid, HEDP, boric acid, NH4VO3, etc.), realizing the directional suppression of the (111) crystal plane and improving the induction effect of (311), (400) and other crystal planes; In this embodiment, the three crystal plane inducing agents of phosphorus-containing compound coordination blocking, boron-containing compound in-situ template and high-valence metal salt lattice strain are combined with the loading material to form a multi-level, multi-scale cathode material crystal structure control strategy, which further improves the effect of suppressing the (111) crystal plane; In this embodiment, the crystal plane induction of the internal core and the physical coating of the surface coating layer are combined to solve the problems of manganese dissolution and structural instability, which greatly improves the electrochemical performance such as cycle life of lithium manganese oxide cathode material.

[0083] In one embodiment, step S10 involves mixing a manganese-containing compound into a dopant containing element M and a supported crystal facet inducer via a doping process, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal facet inducer precursor, comprising:

[0084] A manganese-containing compound is mixed into a dopant containing element M and a first supported crystal facet inducer through a doping process. The first manganese-containing mixture after uniform mixing is pretreated to obtain a first manganese-containing crystal facet inducer precursor. The pH value of the first manganese-containing mixture is 3.0~6.9. The first supported crystal facet inducer is phytic acid / porous silica support or 1-hydroxyethylidene-1,1-diphosphonic acid / porous silica support.

[0085] In one embodiment, step S10 involves mixing a manganese-containing compound into a dopant containing element M and a supported crystal facet inducer via a doping process, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal facet inducer precursor, comprising:

[0086] A manganese-containing compound is mixed into a dopant containing element M and a second supported crystal facet inducer through a doping process. The uniformly mixed second manganese-containing mixture is pretreated to obtain a second manganese-containing crystal facet inducer precursor. The pH value of the second manganese-containing mixture is 7.1~9.0. The second supported crystal facet inducer is a boric acid / magnesium oxide support or a boron oxide / magnesium oxide support.

[0087] In one embodiment, step S10 involves mixing a manganese-containing compound into a dopant containing element M and a supported crystal facet inducer via a doping process, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal facet inducer precursor, comprising:

[0088] Manganese-containing compounds are mixed into dopant containing element M and a third type of supported crystal facet inducer through a doping process. The uniformly mixed third manganese-containing mixture is pretreated to obtain a third manganese-containing crystal facet inducer precursor. The third type of supported crystal facet inducer is ammonium metavanadate / activated carbon support.

[0089] In one embodiment, step S10 involves mixing a manganese-containing compound into a dopant containing element M and a supported crystal facet inducer via a doping process, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal facet inducer precursor, comprising:

[0090] A manganese-containing compound is mixed into a dopant containing element M and a first supported crystal facet inducer through a doping process. After uniform mixing, a first manganese-containing mixture is obtained. The first manganese-containing mixture is subjected to a first pretreatment to obtain a first manganese-containing crystal facet inducer precursor. The pH value of the first manganese-containing mixture is 3.0~6.9. The first supported crystal facet inducer is phytic acid / porous silica support or 1-hydroxyethylidene-1,1-diphosphonic acid / porous silica support.

[0091] The first manganese-containing crystal facet inducing precursor is added to the second supported crystal facet inducing agent and mixed uniformly to obtain the fourth manganese-containing mixture. The fourth manganese-containing mixture is subjected to a second pretreatment to obtain the fourth manganese-containing crystal facet inducing precursor. The pH value of the fourth manganese-containing mixture is 7.1~9.0. The second supported crystal facet inducing agent is boric acid / magnesium oxide support or boron oxide / magnesium oxide support.

[0092] In one embodiment, step S10 involves mixing a manganese-containing compound into a dopant containing element M and a supported crystal facet inducer via a doping process, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal facet inducer precursor, comprising:

[0093] A manganese-containing compound is mixed into a dopant containing element M and a first supported crystal facet inducer through a doping process. After uniform mixing, a first manganese-containing mixture is obtained. The first manganese-containing mixture is subjected to a first pretreatment to obtain a first manganese-containing crystal facet inducer precursor. The pH value of the first manganese-containing mixture is 3.0~6.9. The first supported crystal facet inducer is phytic acid / porous silica support or 1-hydroxyethylidene-1,1-diphosphonic acid / porous silica support.

[0094] The first manganese-containing crystal facet inducing precursor was added to the third supported crystal facet inducing agent and mixed uniformly to obtain the fifth manganese-containing mixture. The fifth manganese-containing mixture was subjected to a third pretreatment to obtain the fifth manganese-containing crystal facet inducing precursor. The third supported crystal facet inducing agent was ammonium metavanadate / activated carbon support.

[0095] In one embodiment, step S10 involves mixing a manganese-containing compound into a dopant containing element M and a supported crystal facet inducer via a doping process, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal facet inducer precursor, comprising:

[0096] A manganese-containing compound is mixed into a dopant containing element M and a second supported crystal facet inducer through a doping process. After uniform mixing, a second manganese-containing mixture is obtained. The second manganese-containing mixture is subjected to a fourth pretreatment to obtain a second manganese-containing crystal facet inducer precursor. The pH value of the second manganese-containing mixture is 7.1~9.0. The second supported crystal facet inducer is boric acid / magnesium oxide support or boron oxide / magnesium oxide support.

[0097] The second manganese-containing crystal facet inducing precursor was added to the third supported crystal facet inducing agent and mixed uniformly to obtain the sixth manganese-containing mixture. The sixth manganese-containing mixture was subjected to the fifth pretreatment to obtain the sixth manganese-containing crystal facet inducing precursor. The third supported crystal facet inducing agent was ammonium metavanadate / activated carbon support.

[0098] In one embodiment, step S10 involves mixing a manganese-containing compound into a dopant containing element M and a supported crystal facet inducer via a doping process, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal facet inducer precursor, comprising:

[0099] A manganese-containing compound is mixed into a dopant containing element M and a first supported crystal facet inducer through a doping process. After uniform mixing, a first manganese-containing mixture is obtained. The first manganese-containing mixture is subjected to a first pretreatment to obtain a first manganese-containing crystal facet inducer precursor. The pH value of the first manganese-containing mixture is 3.0~6.9. The first supported crystal facet inducer is phytic acid / porous silica support or 1-hydroxyethylidene-1,1-diphosphonic acid / porous silica support.

[0100] The first manganese-containing crystal facet inducing precursor is added to the second supported crystal facet inducing agent and mixed uniformly to obtain the fourth manganese-containing mixture. The fourth manganese-containing mixture is subjected to a second pretreatment to obtain the fourth manganese-containing crystal facet inducing precursor. The pH value of the fourth manganese-containing mixture is 7.1~9.0. The second supported crystal facet inducing agent is boric acid / magnesium oxide support or boron oxide / magnesium oxide support.

[0101] The fourth manganese-containing crystal facet inducing precursor was added to the third supported crystal facet inducing agent and mixed uniformly to obtain the seventh manganese-containing mixture. The seventh manganese-containing mixture was subjected to the sixth pretreatment to obtain the seventh manganese-containing crystal facet inducing precursor. The third supported crystal facet inducing agent was ammonium metavanadate / activated carbon support.

[0102] In one embodiment, the first, second, third, fourth, fifth, and sixth pretreatments are all performed by heating at 300°C to 500°C for 2 to 5 hours. Pretreatment allows the facet inducer (such as phytic acid) in the supported facet inducer to undergo sufficient chemical and physical interactions with the manganese precursor surface, thus pre-coordinating and covering the facet inducer with the (111) facet. The low-temperature treatment at 300°C to 500°C makes the facet inducer molecules more firmly bonded to the manganese source, but does not trigger large-scale crystallization of lithium manganese oxide, further improving the facet induction effect during crystal growth.

[0103] The effective effects of the above embodiments are detailed above. Several supported crystal face inducing agents are combined according to specific needs to obtain manganese-containing crystal face inducing precursors with different crystal face induction effects. Among them, by controlling the pH value of the manganese-containing mixture to 3.0~6.9, keeping the manganese-containing mixture in a weakly acidic environment is more conducive to the adsorption capacity of phosphonate, and improving the ability of molecules in the first supported crystal face inducing agent to fully and selectively adsorb on the (111) crystal face of manganese precursor particles. The pH value of the manganese-containing mixture to 7.1~9.0, keeping the manganese-containing mixture in a weakly alkaline environment is more conducive to the stability of magnesium oxide, and improving the release stability of the second supported crystal face inducing agent and the formation of a thin film on the (111) crystal face. In addition, in the early stage of hydrothermal or solid-phase sintering, NaBH4 in an alkaline hydrothermal environment or B2O3 at high temperature will generate an amorphous borate glass phase. During crystal growth, the borate template phase covers the (111) crystal face and plays a role in inhibiting the growth of the (111) crystal face.

[0104] In one embodiment, the preparation method of the first supported crystal facet inducer includes: dispersing porous silica nanoparticles in an aqueous solution of phytic acid or 1-hydroxyethylidene-1,1-diphosphonic acid, stirring, impregnating, and drying to obtain the first supported crystal facet inducer; the porous silica nanoparticles include MCM-41, SBA-15, or fumed silica. This embodiment enables phytic acid molecules or HEDP molecules to be fully adsorbed on the mesoporous channels and large surfaces of silica.

[0105] In one embodiment, the preparation method of the second supported crystal facet inducer includes: loading boric acid or boron oxide onto light magnesium oxide nanoparticles by impregnation or solid-phase ball milling to obtain the second supported crystal facet inducer.

[0106] In one embodiment, the preparation method of the third supported crystal facet inducer includes: dissolving ammonium metavanadate, mixing it with activated carbon with a high specific surface area, and drying it to obtain a powder, thereby obtaining the third supported crystal facet inducer. In this embodiment, the activated carbon has abundant functional groups and a large specific surface area, which can effectively adsorb and fix vanadium / molybdate ions. The rate at which the activated carbon releases ammonium metavanadate is controlled in the early stages of sintering, achieving more uniform micro-doping and lattice strain induction.

[0107] The atomic percentage of the crystal face induction element in the first, second, and third supported crystal face induction agents in the lithium manganese oxide cathode material is 0.1 at% to 0.5 at%. Too little crystal face induction will result in poor crystal face induction effect, while too much crystal face induction will cause crystal structure imbalance.

[0108] In one embodiment, the manganese compound in S10 is one or more of Mn3O4, MnO2 and Mn2O3;

[0109] And / or, the doping process is solid-phase doping or liquid-phase doping;

[0110] And / or, the lithium salt is one or more combinations of lithium hydroxide, lithium carbonate and lithium nitrate;

[0111] And / or, in S10, the pretreatment involves heating the manganese-containing mixture at 300°C to 500°C for 2 to 5 hours;

[0112] And / or, the conditions for the first sintering in S11 are: in an air or oxygen atmosphere, the heating rate is 1℃ / min~5℃ / min, the first stage sintering temperature is 300℃~600℃, the sintering time is 2h~6h, the second stage sintering temperature is 700℃~900℃, and the sintering time is 12h~30h.

[0113] And / or, the coating in S12 is performed by solid-phase coating or liquid-phase coating;

[0114] And / or, the conditions for the second sintering in S12 are: in an air or oxygen atmosphere, the heating rate is 1℃ / min to 5℃ / min, the sintering temperature is 300℃ to 750℃, and the sintering time is 6h to 24h.

[0115] The process parameters used in this embodiment can improve the stability of the electrochemical performance of lithium manganese oxide cathode material. Other doping processes, types of manganese-containing compounds, types of lithium salts, and process parameters will reduce the electrochemical performance of lithium manganese oxide cathode material.

[0116] In another embodiment, based on the mass content distribution of doping elements in the core, the modified doped layer includes a doping modification layer and a molten metal oxide layer; the general chemical formula of the lithium manganese oxide matrix is ​​Li. 1+y Mn 2-x J x O4, where 0≤y<0.1, 0≤x<2, and J is the matrix dopant ion;

[0117] The general chemical formula of the modified doped layer is Li f Mn g K' h O2, where 0≤f<1, 0≤g<1, 0≤h<1, and K' is a modified dopant ion.

[0118] In another embodiment, J is Mg 2+ Cu 2+ Ni 2+ Co 2+ Al 3+ Zn 2+ Fe 3+ or Cr 3+ One or more combinations of Sr; K' is Sr 2+ Ni 2+ Ni 3+ Yb 3+ Y 3+ Co 3+ Mo 6+ Sn 4+ 、Sm 3+ 、Tb 3+ In 3+ or W 6+ One or more combinations thereof.

[0119] like Figure 5 As shown, the preparation of a multifunctional layered lithium manganese oxide cathode material as described in any other embodiment includes:

[0120] S20. Dissolve soluble manganese salt, soluble compound containing J element and supported crystal facet inducer in water to obtain mixed metal ion solution;

[0121] S21. Gas is introduced into the mixed metal ion solution, pH is adjusted to the specified value by adding pH adjuster, the reaction is heated and stirred, and after the reaction is completed, the solution is aged, washed, filtered and dried to obtain the manganese crystal facet-induced precursor.

[0122] S22. The lithium source is mixed with the manganese crystal plane-induced precursor, a dopant containing K' element is added, and the mixture is ground, mixed, calcined for the first time, and cooled to obtain the lithium manganese oxide core.

[0123] S23. The lithium manganese oxide core is coated with a coating material containing M' element, and then calcined a second time to obtain a multifunctional layered lithium manganese oxide cathode material.

[0124] In this embodiment, the primary particles of the multifunctional layered manganese phosphate cathode material have a near-spherical morphology, and the thickness of the modified doped layer is 8 nm to 200 nm.

[0125] In another embodiment, in step S20, the soluble manganese salt is one or more of manganese sulfate, manganese chloride, and manganese nitrate, and the soluble compound containing element J is one or more of oxides, hydroxides, oxalates, acetates, sulfates, chlorides, nitrates, or phosphates containing element J. The molar ratio of the soluble manganese salt to the soluble compound containing element J is (3000-50):1. In step S20, the soluble manganese salt and the Mg-containing compound are... 2+ Cu 2+ Ni 2+ Co 2 + Al 3+ Soluble salts of low-valence metal elements are dissolved in water to form a mixed metal ion solution. The key to this step is ensuring uniform dispersion of the metal ions in the solution, providing a homogeneous basis for subsequent ion doping. These low-valence metal elements are chosen because they have small ionic radii, allowing for uniform doping into the lithium manganese oxide matrix. This uniform doping is crucial for improving the material's performance.

[0126] In another embodiment, the gas introduced in step S21 is any one of air, nitrogen, argon, argon-hydrogen mixture, or nitrogen-argon mixture, and the pH adjuster is one or more of ammonia, sodium hydroxide, or potassium hydroxide, and the specified pH value is adjusted to 7.5 to 11. In step S21, the pH value of the solution is adjusted by introducing gas or adding a pH adjuster, which promotes the ion doping reaction. The pH value is used to regulate the reaction rate.

[0127] In another embodiment, the conditions for heating and stirring the reaction in step S21 are as follows: stirring temperature is 50~90℃, reaction time is 2~8h, and aging time is 8~12h; in step S22, the lithium source is one or more of lithium hydroxide monohydrate, lithium hydroxide, lithium oxalate, lithium carbonate, lithium nitrate, lithium acetate, lithium fluoride, lithium chloride, lithium tert-butoxide, or lithium citrate, and the molar ratio of Li in the lithium source to Mn in the precursor is 1:(0.51~0.56); in step S22, the dopant containing K' element is one or more of rare earth element oxides, alkaline earth metal element oxides, hydroxides, oxalates, acetates, chlorides, nitrates, sulfates, carbonates, or phosphates containing K' element, and the amount of dopant containing K' element added is between 250~5000ppm; the dopant can act as a charge carrier, promote the diffusion of lithium ions in the electrode material, thereby improving the overall performance of the battery.

[0128] In another embodiment, the conditions for the first calcination in step S22 are: pre-calcination at 300~600℃ for 1~6 hours, followed by sintering at 700~950℃ for 6~24 hours. In step S22, the precursor is mixed with a lithium source, and a Ca-containing compound is added. 2+ 、Sr 2+ Yb 3 + Ce 3+ Ba 2+ Dopants such as low-valence, large-atomic-radius elements are introduced. These elements are used to perform manganese substitution at the manganese site in the modified doped layer structure of lithium manganese oxide, thereby reducing Mn. 3+ The concentration of [specific concentration] suppressed the Jahn-Teller effect, thereby improving the cycling stability of the material.

[0129] The advantages of this embodiment compared to the prior art are:

[0130] Bulk doping of lithium manganese oxide matrix with low-valence J element, the radius of which is smaller than that of Mn small atomic metal element. 3+ The radius of Mn is easily occupied. 3+ Position, reduced Mn 3+The content of K' element in the modified doping layer is increased, which improves the structural stability of lithium manganese oxide. The K' element, with a large atomic radius, replaces the manganese sites in the modified doping layer and remains on the surface to form a modified doping layer. This reduces the ratio of the (111) crystal plane to the total area in the lattice, thus changing the morphology of lithium manganese oxide particles from a regular octahedron with sharp edges to a truncated octahedron. Simultaneously, by using a supported crystal plane inducer and altering the growth orientation of the crystal plane through doping with J element and the crystal plane inducer, the primary particles of lithium manganese oxide are modified by crystal plane induction, further reducing the area of ​​the (111) crystal plane and thus reducing the Mn dissolution reaction. In summary, the modified doped lithium manganese oxide cathode material prepared in this application has a high lithium-ion diffusion coefficient, a stable structure, and better cycle stability and rate performance.

[0131] In another embodiment, the thickness of the modified doped layer is 8 nm to 200 nm. Within this thickness range, the modified doped layer may improve the electrochemical activity of the electrode material by providing a surface structure more suitable for lithium-ion diffusion and insertion. The modified doped layer may help increase the lithium-ion transport rate in the electrode material, and an appropriate layer thickness can provide good mechanical support, reduce stress concentration, and thus improve the overall charge-discharge efficiency of the battery.

[0132] In order to enable those skilled in the art to clearly understand the above-described implementation details and operations of this application, and to demonstrate the significant improvement in performance of the embodiments of this application, the above technical solutions are illustrated below through multiple embodiments.

[0133] Preparation Example 1

[0134] The preparation method of the first supported crystal plane inducer includes:

[0135] 2g of mesoporous silica nanoparticles (porous silica nanoparticles with a specific surface area ≥600m²) were added. 2 Disperse (g) in 100 mL of deionized water and sonicate for 30 minutes to ensure complete dispersion of silica;

[0136] Under high-speed stirring (e.g., stirring speed of 1200 r / min to 1600 r / min), 1 g of phytic acid aqueous solution (phytic acid concentration of 50 wt%) is slowly added dropwise to the silica dispersion;

[0137] Stirring continuously in a 40℃ constant temperature water bath for 6 hours allows phytic acid molecules to fully diffuse and adsorb into the mesoporous channels of silica.

[0138] The mixture was dried in a forced-air drying oven at 100°C for 12 hours to completely remove moisture.

[0139] The dried block product was gently ground in an agate mortar to obtain phytic acid / silica supported powder, which is the first supported crystal facet inducer.

[0140] Preparation Example 2

[0141] The preparation method of the second supported crystal plane inducer includes:

[0142] 1.0g of nano-magnesium oxide (average particle size of magnesium oxide ≤50nm) and 0.2g of boric acid powder were initially mixed in an agate mortar;

[0143] Add anhydrous ethanol dropwise (2 mL to 3 mL total) while grinding rapidly to allow the solvent to cause the NaBH4 microcrystals to adhere evenly to the surface of the MgO particles.

[0144] Continue grinding for 30 to 60 minutes to form a uniform slurry;

[0145] The slurry was dried in a drying oven at 60°C under an inert atmosphere (such as argon) for 4 hours to prevent NaBH4 oxidation and hydrolysis.

[0146] After drying, the mixture is gently ground to obtain boric acid / magnesium oxide supported powder, which is then sealed and stored to obtain the second supported crystal facet inducer.

[0147] Preparation Example 3

[0148] The preparation method of the third supported crystal plane inducer includes:

[0149] Dissolve 0.2 g of ammonium metavanadate in 5.4 mL of warm deionized water at 50 °C, and stir until completely dissolved to obtain a clear, pale yellow solution.

[0150] Add 3.0g of activated carbon powder (the specific surface area of ​​activated carbon is ≥1000m²). 2 Place the g in an evaporating dish or beaker.

[0151] Using a pipette or burette, slowly add the prepared 5.4 mL hot ammonium metavanadate solution dropwise onto the activated carbon in small, frequent increments. During the addition, stir rapidly to obtain the loading material, ensuring the solution is uniformly absorbed by the activated carbon. No free liquid should remain after the entire process.

[0152] Seal the moistened loading material and age it at room temperature for 4-6 hours to allow the active ingredients to be more evenly distributed inside the pores.

[0153] The aged material was then transferred to a drying oven and dried at 80°C for 6 hours, followed by drying at 120°C for 2 hours to obtain block material, thus removing moisture.

[0154] After drying, the blocky material is gently ground in an agate mortar to obtain a black ammonium metavanadate / activated carbon supported inducer powder, which is the third supported crystal face inducer.

[0155] Example 1:

[0156] Preparation of a multifunctional layered lithium manganese oxide cathode material:

[0157] S10. The manganese-containing compound is mixed into a dopant containing nickel (M element) and a first-type supported crystal plane inducer through a doping process. The uniformly mixed manganese-containing mixture is pretreated to obtain a manganese-containing crystal plane inducer precursor.

[0158] Specifically:

[0159] In step S100, 10L of pure water was added to a 50L reactor as the base solution. The stirring speed was controlled at 500r / min, and the temperature was maintained at 60℃. A 9mol / L ammonia solution was added until the pH of the reactor reached 12. Manganese sulfate solution and nickel sulfate solution were then added to the reactor to obtain a mixed metal salt solution doped with nickel. The molar ratio of the mixed metal salt solution doped with nickel to NaOH was maintained at 1:2, and the molar ratio of NaOH solution to ammonia was maintained at 1:1. The pH of the reactor was maintained at 11. The reaction was continued to synthesize a slurry of nickel-doped manganese tetroxide precursor. The slurry was then washed with deionized water, filtered, and dried at 120℃ for 12h to obtain a spherical manganese tetroxide precursor doped with Ni with a particle size D50 of 7μm.

[0160] S101. Phytic acid / silica support (first supported crystal face inducing agent) and Ni-doped spherical manganese tetroxide precursor are added to pure water at a mass ratio of 1.5:100 and mixed evenly to obtain a first manganese-containing mixture. The pH value of the first manganese-containing mixture is adjusted to 5.0 with 0.1 mol / L acetic acid solution. The first manganese-containing mixture is then pretreated by heating it at 400℃ for 3.5 h to obtain a manganese-containing crystal face inducing precursor.

[0161] S11. After mixing the manganese-containing crystal plane-induced precursor with dopants containing Ti (X element), W (R element), and F (Z element) and lithium hydroxide (lithium salt), a first sintering is performed to obtain a lithium manganese oxide core.

[0162] Specifically, lithium hydroxide, a manganese-containing crystal-facet-induced precursor, TiO2, W2O3, and LiF are mixed at high speed in a high-speed mixer, maintaining a lithium to manganese molar ratio of 0.53:1. The Ti doping concentration in the lithium manganese oxide cathode material is 1934 ppm, the W doping concentration is 1687 ppm, and the F doping concentration is 897 ppm. The mixture is then placed in a track furnace for the first sintering process, with the first sintering temperature at 450°C for 4 hours, followed by a second sintering at 800°C for 16 hours in a compressed air atmosphere. This yields a lithium manganese oxide core doped with Ni and F in bulk, modified with Ti, and induced by W crystal faces. In this application, ppm (parts per million) refers to the mass percentage of a specific element in the cathode material out of the total mass of the cathode material.

[0163] S12. The lithium manganese oxide core is coated with a coating containing aluminum (M' element), and a second sintering is performed to obtain a multifunctional layered lithium manganese oxide cathode material.

[0164] Specifically, the obtained lithium manganese oxide core and Al2O3 powder are added together into a high-speed mixer, where the Al coating accounts for 4698 ppm of the entire lithium manganese oxide cathode material. The mixed powder is mixed at 800 r / min for 20 min. The resulting uniformly mixed powder is then subjected to a second sintering, i.e., annealing at 600℃ for 12 h in a compressed air atmosphere, to obtain a multifunctional layered lithium manganese oxide cathode material with 3941 ppm Ni and 897 ppm F bulk phase doping, 1687 ppm W crystal face induction, 1934 ppm Ti modification doping, and Al2O3 surface coating.

[0165] Figure 6 This is a schematic diagram of the multifunctional layers of the lithium manganese oxide cathode material in Example 1, based on the mass content distribution of each element. The diagram shows the elemental distribution of the lithium manganese oxide cathode material (LMO) in different functional layers based on mass. It can be seen that the lithium manganese oxide core has four functional regions. Bulk dopants are uniformly distributed within the lithium manganese oxide core particles. Crystalline induction elements have a higher distribution on the surface of the lithium manganese oxide core, decreasing towards the interior. Modifying dopants are mainly distributed on the surface of the lithium manganese oxide core particles, forming a modifying doped layer. After modification by these functional layers, an outermost coating layer is constructed on the surface of the lithium manganese oxide core particles. There is overlap in the distribution of modifying dopants, crystalline induction elements, and bulk dopants in the modifying doped layer. There is also some overlap in the crystalline induction elements and bulk dopants in the induction doped layer of the lithium manganese oxide core. However, towards the bulk center of the lithium manganese oxide matrix, the distribution is mainly bulk doped. The bulk doping distribution is relatively uniform throughout the material.

[0166] Example 2:

[0167] Unlike Example 1, the supported crystal facet inducer in step S101 was replaced with the second supported crystal facet inducer (boron oxide / magnesium oxide support) of Preparation Example 2.

[0168] S101. Then, the boron oxide / magnesium oxide support (second supported crystal face inducing agent) and the Ni-doped spherical manganese tetroxide precursor are added to pure water at a mass ratio of 1.5:100 and mixed evenly to obtain a second manganese-containing mixture. The pH value of the second manganese-containing mixture is adjusted to 8.0 with 0.1 mol / L sodium bicarbonate solution. The second manganese-containing mixture is heated at 400℃ for 3.5 h to obtain the second manganese-containing crystal face inducing precursor.

[0169] Example 3:

[0170] Unlike Example 1, the supported crystal facet inducer in step S101 was replaced with the third supported crystal facet inducer (ammonium metavanadate / activated carbon support) of Preparation Example 3.

[0171] S101. Then, ammonium metavanadate / activated carbon support (third type of supported crystal face inducing agent) and Ni-doped spherical manganese tetroxide precursor are added to pure water at a mass ratio of 1.0:100 and mixed evenly to obtain a third manganese-containing mixture. The third manganese-containing mixture is heated at 400℃ for 3.5h to obtain a third manganese-containing crystal face inducing precursor.

[0172] Example 4:

[0173] Unlike Example 1, the supported crystal plane inducer in step S101 was replaced with the first supported crystal plane inducer (phytic acid / silica support) and the second supported crystal plane inducer (boron oxide / magnesium oxide support) of Preparation Examples 1 and 2.

[0174] S101. Phytic acid / silica support (first supported crystal face inducing agent) and Ni-doped spherical manganese tetroxide precursor are added to pure water at a mass ratio of 1.5:100 and mixed evenly to obtain a first manganese-containing mixture. The pH value of the first manganese-containing mixture is adjusted to 5.0 with 0.1 mol / L acetic acid solution. The first manganese-containing mixture is then heated at 400℃ for 3.5 h to obtain the first manganese-containing crystal face inducing precursor.

[0175] The first manganese-containing crystal facet inducing precursor was then added to the boron oxide / magnesium oxide support (the second supported crystal facet inducing agent). The added mass of the boron oxide / magnesium oxide support was the same as that of the phytic acid / silica support. After uniform mixing, a fourth manganese-containing mixture was obtained. The pH value of the fourth manganese-containing mixture was adjusted to 8.0 with 0.1 mol / L sodium bicarbonate solution. The fourth manganese-containing mixture was heated at 400℃ for 3.5 h to obtain the fourth manganese-containing crystal facet inducing precursor.

[0176] Example 5:

[0177] Unlike Example 1, the supported crystal facet inducer in step S101 was replaced with the first supported crystal facet inducer (phytic acid / silica support) and the third supported crystal facet inducer (ammonium metavanadate / activated carbon support) of Preparation Examples 1 and 3.

[0178] S101. Phytic acid / silica support (first supported crystal face inducing agent) and Ni-doped spherical manganese tetroxide precursor are added to pure water at a mass ratio of 1.5:100 and mixed evenly to obtain a first manganese-containing mixture. The pH value of the first manganese-containing mixture is adjusted to 5.0 with 0.1 mol / L acetic acid solution. The first manganese-containing mixture is heated at 400℃ for 3.5 h to obtain the first manganese-containing crystal face inducing precursor.

[0179] The first manganese-containing crystal facet inducing precursor was then added to the ammonium metavanadate / activated carbon support (the third supported crystal facet inducing agent). The mass ratio of phytic acid / silica support to ammonium metavanadate / activated carbon support was 1.5:1.0. After uniform mixing, the fifth manganese-containing mixture was obtained. The fifth manganese-containing mixture was heated at 400℃ for 3.5h to obtain the fifth manganese-containing crystal facet inducing precursor.

[0180] Example 6:

[0181] Unlike Example 1, the supported crystal facet inducer in step S101 was replaced with the second supported crystal facet inducer (boron oxide / magnesium oxide) and the third supported crystal facet inducer (ammonium metavanadate / activated carbon support) in Preparation Examples 2 and 3.

[0182] S101. Phytic acid / silica support (second supported crystal facet inducer) and Ni-doped spherical manganese tetroxide precursor are added to pure water at a mass ratio of 1.5:100 and mixed evenly to obtain a second manganese-containing mixture. The pH value of the second manganese-containing mixture is adjusted to 8.0 with 0.1 mol / L sodium bicarbonate solution. The second manganese-containing mixture is heated at 400℃ for 3.5 h to obtain the second manganese-containing crystal facet inducer precursor.

[0183] The second manganese-containing crystal facet inducing precursor was then added to the ammonium metavanadate / activated carbon support (the third supported crystal facet inducing agent). The mass ratio of phytic acid / silica support to ammonium metavanadate / activated carbon support was 1.5:1.0. After uniform mixing, the sixth manganese-containing mixture was obtained. The sixth manganese-containing mixture was heated at 400℃ for 3.5h to obtain the sixth manganese-containing crystal facet inducing precursor.

[0184] Example 7:

[0185] Unlike Example 1, the supported crystal facet inducer in step S101 was replaced with the first supported crystal facet inducer (phytic acid / silica support), the second supported crystal facet inducer (boron oxide / magnesium oxide support), and the third supported crystal facet inducer (ammonium metavanadate / activated carbon support) of Preparation Examples 1, 2, and 3.

[0186] S101. Phytic acid / silica support (first supported crystal face inducing agent) and Ni-doped spherical manganese tetroxide precursor are added to pure water at a mass ratio of 1.5:100 and mixed evenly to obtain a first manganese-containing mixture. The pH value of the first manganese-containing mixture is adjusted to 5.0 with 0.1 mol / L acetic acid solution. The first manganese-containing mixture is heated at 400℃ for 3.5 h to obtain the first manganese-containing crystal face inducing precursor.

[0187] The first manganese-containing crystal facet inducing precursor and the boron oxide / magnesium oxide support (the second supported crystal facet inducing agent) were then added to pure water and mixed evenly to obtain the fourth manganese-containing mixture. The pH value of the fourth manganese-containing mixture was adjusted to 8.0 with 0.1 mol / L sodium bicarbonate solution. The fourth manganese-containing mixture was heated at 400℃ for 3.5 h to obtain the fourth manganese-containing crystal facet inducing precursor.

[0188] The fourth manganese crystal facet inducing precursor was then added to the ammonium metavanadate / activated carbon support (the third supported crystal facet inducing agent). The mass ratio of phytic acid / silica support, boron oxide / magnesium oxide support and ammonium metavanadate / activated carbon support was 1.5:1.5:1.0. After uniform mixing, the seventh manganese-containing mixture was obtained. The seventh manganese-containing mixture was heated at 400℃ for 3.5h to obtain the seventh manganese crystal facet inducing precursor.

[0189] Figure 7 This is a cross-sectional SEM image of the lithium manganese oxide cathode material particles from Example 7;

[0190] Example 7 shows the elemental distribution diagrams of Mn, bulk dopant Mn / F, crystal plane induction element Ti, modification dopant element W, and coating element Al in the lithium manganese oxide cathode material, as shown below. Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12, Figure 13 As shown.

[0191] like Figure 14 As shown, the Mn of the existing lithium manganese oxide cathode material 3+ and Mn 4+ The distribution ratios are relatively close, Mn 3+ It is 48.3%, Mn 4+ It is 51.7%; such as Figure 15 As shown, the modified doped layer of the lithium manganese oxide cathode material in Example 1 contains Mn after modification and doping. 4+ Significantly improved, reaching as high as 83.8%.

[0192] Figure 14 This is a schematic diagram of the Mn valence state analysis on the XPS surface of existing lithium manganese oxide cathode materials;

[0193] Figure 15 This is a schematic diagram of the Mn valence state analysis on the XPS surface of the lithium manganese oxide cathode material in Example 7;

[0194] Figure 16 This is a magnified SEM image of lithium manganese oxide cathode material particles from existing technology.

[0195] Figure 17 This is a magnified SEM image of the lithium manganese oxide cathode material particles from Example 7.

[0196] like Figure 18 , Figure 19 , Figure 20 As shown, the octahedral morphology of lithium manganese oxide cathode particles in the prior art results in an incomplete, uneven, and non-rounded coating layer with the presence of broken particles; such as Figure 21 , Figure 22 , Figure 23 As shown, after the morphology of the lithium manganese oxide cathode material in Example 7 evolved into a rounded truncated octahedral morphology, it was beneficial to the modification and uniform adhesion of the coating layer, which improved the integrity of the coating layer and the uniform thickness of the coating layer, thus improving the lifespan and electrochemical performance of the lithium manganese oxide cathode material.

[0197] Figure 21 This is a schematic SEM image of the overall truncated octahedral morphology of the lithium oxide cathode material in Example 7.

[0198] Figure 22 This is a SEM image of the lithium oxide cathode material coating layer in Example 7;

[0199] Figure 23 This is a SEM image of the thickness of the lithium oxide cathode material coating layer in Example 7;

[0200] like Figure 24 As shown, Figure 25 As shown, Figure 24This is a schematic diagram of the linear EDS elemental atomic content of the cross-sectional SEM of the lithium manganese oxide core particles in Example 7. Figure 25 This is a magnified schematic diagram of the linear EDS elemental atomic content of the cross-sectional SEM of the lithium manganese oxide core particles in Example 7. The distribution of each functional layer and each dopant element of the lithium manganese oxide core is consistent in the figure.

[0201] Figure 26 , Figure 27 , Figure 28 The diagrams show the elemental distribution of P in the first supported crystal plane inducer, the elemental distribution of B in the second supported crystal plane inducer, and the elemental distribution of V in the third supported crystal plane inducer for the lithium manganese oxide core particles in Example 7.

[0202] Figure 29 A schematic diagram comparing the crystal XRD patterns of the existing octahedral lithium manganese oxide cathode material and the lithium manganese oxide cathode material of Example 7;

[0203] Figure 30 This is a schematic diagram showing the XRD pattern of the lithium manganese oxide cathode material in Example 7 matched with the standard card PDF#70-3120 for lithium manganese oxide.

[0204] Table 1 shows a comparison of the lattice parameters of the existing octahedral lithium manganese oxide cathode material and the lithium manganese oxide cathode material of Example 7.

[0205] Table 1. Comparison of lattice parameters between existing lithium manganese oxide cathode materials and the lithium manganese oxide cathode material of Example 7.

[0206]

[0207] from Figure 29 The comparison data with Table 1 shows that the (111) crystal surface area of ​​the lithium manganese oxide cathode material in Example 7 is reduced by 21.35% compared with the (111) crystal surface area of ​​the lithium manganese oxide cathode material in the prior art, and the ratio of the (111) crystal surface area to the total area is also reduced, which is beneficial to reduce the dissolution of Mn ions and thus improve the electrochemical performance of the lithium manganese oxide cathode material.

[0208] Example 8:

[0209] Unlike Example 7, the first sintering in step S11 is adjusted to a first-stage sintering temperature of 300°C and a sintering time of 2 hours, and a second-stage sintering temperature of 700°C for 12 hours.

[0210] The second sintering step S12 was adjusted to sintering at 300℃ for 6 hours.

[0211] Example 9:

[0212] Unlike Example 7, the first sintering in step S11 is adjusted to a first-stage sintering temperature of 600°C and a sintering time of 6 hours, and a second-stage sintering temperature of 900°C for 30 hours.

[0213] The second sintering step S12 was adjusted to sintering at 750℃ for 24 hours.

[0214] Example 10:

[0215] Unlike Example 7, step S100 uses a Ni-doped Mn2O3 precursor and lithium carbonate as the lithium source.

[0216] Example 11:

[0217] Unlike Example 7, step S100 uses a Ni-doped MnO2 precursor and lithium carbonate as the lithium source.

[0218] Examples 12-16:

[0219] Unlike Example 7, the mass content of each dopant element and covering element in Examples 12-16 is different, as detailed in Table 2.

[0220] It should be noted that the mass content (ppm) of elements M, Z, X, R, and M' in lithium manganese oxide cathode materials can be obtained by measuring the characteristic spectral lines of the cathode material solution absorption spectrum, such as ICP (Inductively Coupled Plasma Emission Spectrometer) and XAFS (X-ray absorption fine structure spectroscopy). The element type is determined based on the characteristic spectral line wavelength, and the element content is determined based on the characteristic spectral line intensity.

[0221] It should be noted that the thickness of the coating layer can be determined using methods known in the art. As an example, a cross-section of the positive electrode active material particles can be prepared using a cross-section polisher (such as the JEOL IB-09010CP argon-ion cross-section polisher), passing through the core of the lithium manganese oxide positive electrode material particles. Then, elemental analysis using EDX or EDS combined with TEM or SEM (such as the Oxford Instruments X-Max EDS combined with the ZEISS Sigma-02-33 SEM) is performed to obtain the elemental distribution map in the cross-section. The thickness of the coating layer is then determined based on the elemental distribution of the cross-section. More precisely, the thickness values ​​of the coating layer at multiple (more than 3, such as 8, 10, 12, etc.) different locations on the cross-section can be measured, and the average value is recorded as the coating layer thickness.

[0222] It should be noted that the average particle size of lithium manganese oxide cathode material is the average diameter of multiple different orientations of the lithium manganese oxide cathode material particles. For example, based on the elemental distribution map of the cathode material particle cross-section obtained by combining EDX or EDS elemental analysis with TEM or SEM surface scanning tests, multiple (more than 3, such as 8, 10, 12, etc.) different orientation diameters can be obtained from the elemental distribution of the cross-section, and the average value is recorded as the average particle size of lithium manganese oxide cathode material.

[0223] The types and mass contents of each doping element and coating element in Examples 1, 12 to 16 are shown in Table 2.

[0224] Table 2: Doping elements in the examples

[0225]

[0226] Comparative Example 1:

[0227] Unlike Example 7, step S100 does not involve bulk Ni doping.

[0228] Comparative Example 2:

[0229] Unlike Example 7, step S100 does not involve bulk doping with F.

[0230] Comparative Example 3:

[0231] Unlike Example 7, step S11 did not involve adding W to induce crystal planes.

[0232] Comparative Example 4:

[0233] Unlike Example 7, step S11 did not involve adding Ti for modification and doping.

[0234] Comparative Example 5:

[0235] Unlike Example 7, step S12 is omitted, i.e., Al is not coated.

[0236] Comparative Example 6:

[0237] Unlike Example 7, step S11 did not involve adding F for bulk doping or adding W for crystal plane induction.

[0238] Comparative Example 7:

[0239] Unlike Example 7, step S11 did not involve adding F for bulk doping or adding W for crystal plane induction, and step S12 did not involve adding Al for coating.

[0240] Comparative Example 8:

[0241] Unlike Example 7, step S100 did not involve adding Ni for bulk doping; and step S11 did not involve adding Ti for modification doping.

[0242] Comparative Example 9:

[0243] Unlike Example 7, step S100 does not involve adding Ni for bulk doping; there is no step S11, i.e., no F is added for bulk doping, no W is added for crystal plane induction, and no Ti is added for modification doping. Instead, a manganese tetroxide precursor is formed through step S100, and Al is added to coat it to form an octahedral lithium manganese oxide cathode material.

[0244] Comparative Example 10:

[0245] Unlike Example 7, step S100 does not involve adding Ni for bulk doping; there is no step S11, i.e., no adding F for bulk doping, no adding W for crystal plane induction, and no adding Ti for modification doping; and there is no step 12, i.e., no adding Al for coating. Instead, step S100 is used to form a manganese tetroxide precursor and an octahedral lithium manganese oxide cathode material.

[0246] Comparative Example 11:

[0247] Unlike Example 7, step 101 is omitted, i.e., the first supported crystal facet inducer (phytic acid / silica support), the second supported crystal facet inducer (boron oxide / magnesium oxide support), and the third supported crystal facet inducer (ammonium metavanadate / activated carbon support) are not added.

[0248] The types and contents of each doping element and coating element in Comparative Examples 1 to 11 are shown in Table 3.

[0249] Table 3. Types and contents of doping and coating elements in Comparative Examples 1 to 11

[0250]

[0251] Data testing:

[0252] I. Preparation of Button Cells

[0253] The multifunctional lithium manganese oxide cathode material, conductive carbon black, and binder PVDF prepared above were dispersed in the solvent N-methylpyrrolidone (NMP) at a weight ratio of 95:3:2 and mixed evenly to obtain a cathode slurry. The cathode slurry was then uniformly coated onto the cathode current collector aluminum foil, and after drying and cold pressing, a cathode electrode sheet was obtained.

[0254] In the coin cell, the positive electrode, separator and lithium metal sheet are stacked in sequence and injected with the electrolyte to assemble a coin cell.

[0255] II. Preparation of Full Cells

[0256] The above-prepared positive electrode active material, conductive agent acetylene black and binder PVDF are dispersed in solvent NMP at a weight ratio of 95:3:2 and mixed evenly to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained.

[0257] The negative electrode active materials, artificial graphite, hard carbon, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are dispersed in deionized water at a weight ratio of 90:5:2:2:1 and mixed evenly to obtain a negative electrode slurry. The negative electrode slurry is then evenly coated onto the negative electrode current collector aluminum foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0258] A porous polypropylene (PP) polymer film is used as the separator. The positive electrode, separator, and negative electrode are stacked in sequence to obtain a bare cell. The bare cell is placed in an outer package, injected with the electrolyte, and sealed. After formation and other processes, a full cell is obtained.

[0259] III. Testing Section

[0260] (1) Test the mass ratio of each space in the first space, second space and third space of the lithium manganese oxide cathode material of this application.

[0261] The lithium manganese oxide cathode material particles of this application were obtained using IB from JEOL Corporation. Cross-sections of lithium manganese oxide cathode material particles were prepared using a 09010CP type cross-section polishing instrument. The elemental distribution in the cross-section was analyzed using an X-Max energy dispersive spectroscopy (EDS) instrument from Oxford Instruments (UK) combined with a Sigma-02-33 scanning electron microscope (SEM) from ZEISS (Germany). The analysis method was as follows: Elements detected included bulk doped M and Z elements, crystal plane-induced X elements, modified doped R elements, and coated M' elements. SEM parameters were set to 20kV accelerating voltage, 60μm aperture, 8.5mm working distance, and 2.335A current. During EDS testing, the test was stopped when the spectral area reached more than 250,000 cts (controlled by acquisition time and rate), and data was collected. Based on the elemental distribution in the cross-section, the first space from the surface to the interior of the multifunctional layer lithium manganese oxide cathode material, at a distance of 1 / 5 radius r of the average particle size of the multifunctional layer lithium manganese oxide cathode material, was obtained (i.e.,...). Figure 3The mass ratio ω1 of the sum of the masses of each doped element and the coating element in the space within the thickness range r1 from the outer surface of the medium-sized particles to the inner dashed line 1 is given by the second space from the point 1 / 2 radius r of the average particle size of the multifunctional lithium manganese oxide cathode material to the surface. Figure 3 The mass ratio ω2 of the modified doped elements to the bulk doped elements in the space within the thickness range r2 from the outer surface of the medium-sized particles to the inner dashed line 2, and the mass ratio ω3 of the crystal plane-induced elements to the bulk doped elements in the second space; based on the cross-sectional element distribution, the third space from the radius r of 2 / 3 of the average particle size of the multifunctional lithium manganese oxide cathode material to the surface (i.e., Figure 3 The mass ratio ω4 is the sum of the masses of each doped element and coating element in the space within the thickness range r3 from the outer surface of the medium particle to the inner dashed line 3, and the total mass of each doped element and coating element in the multifunctional layered lithium manganese oxide cathode material.

[0262] The mass ratios of the lithium manganese oxide cathode materials in Examples 1 to 16 are shown in Table 4.

[0263] Table 4. Mass ratios of lithium manganese oxide cathode materials in Examples 1 to 16

[0264]

[0265] Test data for button cells and full cells of Examples 1-16 and Comparative Examples 1-11 are shown in Tables 5 and 6.

[0266] Table 5 Test data for button cells and full cells in Examples 1-16

[0267]

[0268] Table 6 Test data for comparative examples 1–11 coin cells and full cells

[0269]

[0270] Based on the comparison results of Examples 1-16 and Comparative Examples 1-11, it can be seen that by uniform bulk doping of M and Z elements, crystal plane induction of X element and modification doping of R element, and then covering the surface of lithium manganese oxide cathode material core particles with a coating layer including M' element, lithium-ion secondary batteries can have high initial discharge specific capacity and excellent high-temperature cycling and high-temperature storage performance.

[0271] Example 17:

[0272] A method for preparing a multifunctional lithium manganese oxide cathode material includes:

[0273] S20, manganese sulfate, aluminum sulfate, and zinc sulfate are dissolved in water at a molar ratio of Mn:Al:Zn = 1.958:0.04:0.002 to obtain a mixed solution of manganese sulfate, aluminum sulfate, and zinc sulfate with a metal ion concentration of 2 mol / L. Then, boron oxide / magnesium oxide support (second-type supported crystal facet inducing agent) is added to the mixed solution of metal ions to obtain a mixed solution of crystal facet inducing ions. The mass ratio of boron oxide / magnesium oxide support to manganese tetroxide precursor is 1.5:100.

[0274] S21, under air environment, 6 mol / L ammonia water was added to the mixed solution of crystal facet-induced ions to adjust the pH of the reaction system to 8.5. The reaction was heated and stirred at 65℃ for 4 hours. After the co-precipitation reaction was completed, the mixture was aged for 10 hours. After drying by hot alkali filtration, the doped manganese-containing crystal facet-induced precursor, namely aluminum and zinc co-doped manganese tetroxide precursor, was obtained.

[0275] S22, weigh 100g of manganese crystal plane-inducing precursor, and follow the chemical formula LiMn 1.958 Al 0.04 Zn 0.002 O4 is mixed with lithium carbonate, and then tungsten oxide (doped at 3500 ppm) and calcium carbonate (doped at 500 ppm) are added, ground and mixed, calcined at 500℃ for 2 h, then calcined at 760℃ for 18 h, and cooled to room temperature to obtain Al. 3+ Zn 2+ W 6+ Ca 2+ Co-doped lithium manganese oxide core.

[0276] S23, the lithium manganese oxide core is coated with a coating containing aluminum (M' element), and a multifunctional layered lithium manganese oxide cathode material is obtained by second sintering.

[0277] Specifically, the obtained lithium manganese oxide core and Al2O3 powder were added together into a high-speed mixer, where the Al coating amount accounted for 4698 ppm of the entire lithium manganese oxide cathode material. The powder was mixed at 800 r / min for 20 min. The resulting uniformly mixed powder was then subjected to a second sintering, i.e., annealing at 600℃ for 12 h in a compressed air atmosphere, to obtain Al2O3. 3+ Zn 2+ Bulk doping, W 6+ Ca 2+ Multifunctional lithium manganese oxide cathode material with crystal facet induction and modification doping and Al2O3 surface coating.

[0278] Example 18:

[0279] The difference between this embodiment and embodiment 17 is that in step S22, 3500 ppm of tungsten oxide and 500 ppm of calcium carbonate are replaced with 3500 ppm of strontium carbonate.

[0280] S22, weigh 100g of manganese crystal plane-inducing precursor, and follow the chemical formula LiMn 1.958 Al 0.04 Zn 0.002 O4 is mixed with lithium carbonate, and then 3500 ppm of strontium carbonate is added and ground. The mixture is then calcined at 550°C for 2 hours, followed by calcination at 750°C for 18 hours, and then cooled to room temperature to obtain Al. 3+ Zn 2+ and Sr 2+ Doped lithium manganese oxide core.

[0281] Example 19:

[0282] The difference between this embodiment and embodiment 17 is that in step S22, 3500ppm tungsten oxide and 500ppm calcium carbonate are replaced with 3500ppm tungsten oxide.

[0283] S22, weigh 100g of manganese crystal plane-inducing precursor, and follow the chemical formula LiMn 1.958 Al 0.04 Zn 0.002 O4 is mixed with lithium carbonate, and then 3500 ppm of tungsten oxide is added and ground. The mixture is then calcined at 550°C for 2 hours, followed by calcination at 750°C for 18 hours, and then cooled to room temperature to obtain the Al. 3+ Zn 2+ W 6+ Doped lithium manganese oxide core.

[0284] Comparative Example 12:

[0285] The difference from Example 17 is that aluminum sulfate and zinc sulfate solutions were not added in step S20, and 3500 ppm of tungsten oxide and 500 ppm of calcium carbonate were not added in step S22. Otherwise, it is the same as Example 17.

[0286] A method for preparing a multifunctional lithium manganese oxide cathode material includes the following steps:

[0287] S20 is used to prepare a manganese sulfate metal ion solution with a metal ion concentration of 2 mol / L.

[0288] S21, under air conditions, 6 mol / L ammonia water was added to the manganese sulfate metal ion solution to adjust the pH of the reaction system to 8.5. The reaction was heated and stirred at 65℃ for 4 hours. After the co-precipitation reaction was completed, the mixture was aged for 10 hours. The oxide precursor, namely manganese tetroxide, was obtained by hot alkali filtration and drying.

[0289] S22: Weigh 100g of manganese tetroxide, grind and mix it with lithium carbonate according to the chemical formula LiMn2O4, calcine at 500℃ for 2h, then calcine at 760℃ for 18h, and cool to room temperature to obtain lithium manganese oxide core.

[0290] Figure 31 The figure shows a comparison of the XRD patterns of the lithium manganese oxide cathode materials prepared in Example 1 and Comparative Example 12. As can be seen from the figure, the peak intensity ratio, peak shape and peak position of the diffraction peaks of the Comparative Example 12 sample are significantly weaker than those of Example 17, indicating that the degree of crystallinity of the material is worse than that of Example 17.

[0291] Figure 32 This is a schematic diagram comparing the rate curves of the electrode materials obtained in Example 17 and Comparative Example 12. It can be seen from the figure that the rate performance of Comparative Example 12 is far inferior to that of Example 17. At a current density of 7C, the discharge specific capacity of the modified lithium manganese oxide sample is ~10mAh / g higher than that of the original sample, indicating that the method provided in this application can effectively improve the rate performance of the material.

[0292] Comparative Example 13:

[0293] The difference from Example 17 is that aluminum sulfate and zinc sulfate solutions were not added in step S20, but otherwise the same as in Example 17.

[0294] This application provides a method for preparing a multifunctional lithium manganese oxide cathode material, including the following steps:

[0295] S20 is used to prepare a manganese sulfate metal ion solution with a metal ion concentration of 2 mol / L.

[0296] S21, under air conditions, 6 mol / L ammonia water was added to the manganese sulfate metal ion solution to adjust the pH of the reaction system to 8.5. The reaction was heated and stirred at 65℃ for 4 hours. After the co-precipitation reaction was completed, the mixture was aged for 10 hours. The oxide precursor, namely manganese tetroxide, was obtained by hot alkali filtration and drying.

[0297] S22, weigh 100g of manganese tetroxide, prepare lithium carbonate according to the chemical formula LiMn2O4, add 3500ppm tungsten oxide and 500ppm calcium carbonate, grind and mix, calcine at 550℃ for 3h, then calcine at 700℃ for 15h, cool to room temperature to obtain the cathode material.

[0298] Figure 33 W prepared for Comparative Example 13 6+ Ca 2+ The SEM image of the doped lithium manganese oxide cathode material shows that the surface of the material is not clean, the particles are agglomerated, and a thin film is formed on the surface of the material, which is inconsistent with the expected smooth and clean surface.

[0299] Comparative Example 14:

[0300] The difference between this embodiment and embodiment 17 is that the calcination conditions in step S22 are replaced with calcination at 500°C for 2 hours and calcination at 550°C for 18 hours.

[0301] The lithium manganese oxide core in this comparative example was sintered at too low a temperature. This low temperature resulted in incomplete melting of the metal oxides (such as WO3 and CaCO3), leading to uneven and incomplete coating thickness. The incompletely coated portions were directly exposed to the electrolyte, exacerbating Mn dissolution and electrolyte decomposition, resulting in rapid capacity decay.

[0302] Comparative Example 15:

[0303] The difference between this comparative example and Example 17 is that the calcination conditions in step S22 are replaced with calcination at 600°C for 2 hours and calcination at 980°C for 18 hours.

[0304] Figure 34 This is a SEM image of the coating layer of the lithium manganese oxide cathode material in Comparative Example 15.

[0305] Figure 35 This is a SEM image of the lithium manganese oxide cathode material particles in Comparative Example 15.

[0306] The lithium manganese oxide cathode material in this comparative example was calcined at too high a temperature. The high temperature caused excessive grain growth, forming large agglomerates, reducing the specific surface area, decreasing the lithium-ion diffusion efficiency, and creating a slab structure that hindered electrolyte penetration. The spinel structure was obvious, the coating layer became thinner, and the cycle performance deteriorated.

[0307] Electrochemical performance parameters of Examples 17 to 19 and Comparative Examples 12 to 15 were tested, and the test data are shown in Tables 7 and 8.

[0308] Table 7. Initial discharge capacity at 0.2C and capacity retention after 300 cycles for the lithium manganese oxide cathode materials obtained in Examples 17 to 19 and Comparative Examples 12 to 15.

[0309]

[0310] Table 8. Initial discharge capacity at 0.2C and capacity retention after 100 cycles for the lithium manganese oxide cathode materials obtained in Examples 17 to 19 and Comparative Examples 12 to 13 at high temperature (55°C).

[0311]

[0312] Figure 36 This is a schematic diagram of the linear EDS elemental atomic content of the cross-sectional SEM of the lithium manganese oxide cathode material particles in Example 17. Figure 37This is a magnified linear EDS schematic diagram of the elemental atomic content of the modified doped layer of the lithium manganese oxide cathode material in Example 17, obtained by cross-sectional SEM.

[0313] The distribution of oxygen and metallic elements in the cross-sectional elemental distribution diagram allows for the analysis of the molten layer of the metal oxide. On the material surface, the concentrations of oxygen (corresponding to the OK curve) and the metallic elements constituting the metal oxide (such as those represented by the WL, Ca, and K curves) show a high degree of overlap in a certain region. Starting from the horizontal axis of the cross-sectional line scan (i.e., the material surface), moving towards a certain thickness within the material, up to a certain depth covered by the horizontal axis, the concentrations of these two types of elements rise and fall synchronously, exhibiting a closely correlated distribution. Moreover, the concentration curves of these two types of elements show basically consistent trends, with similar peak or trough shapes. Due to the molten coating mechanism, the resulting coating layer is continuous, reflected in the concentration curve as a relatively consistent high-concentration range, without obvious abrupt changes or discrete distributions.

[0314] For the doped modified layer, the spectra show that the distribution curves of some metal elements constituting the metal oxide (such as the elements corresponding to the WL, CaK, etc. curves) in the surface doped modified layer exhibit a certain upward and downward trend, which is different from the trend of oxygen (OK curve). This indicates that the modified doped layer consists of two layers: the doped modified layer and the molten metal oxide layer.

[0315] Compared with other examples and comparative examples, the material in Example 17 exhibits significant advantages in electrochemical performance. Tables 7 and 8 show that the lattice size is reduced, and the migration channels for lithium ions are broadened. Furthermore, the manganese oxide / magnesium oxide crystal facet inducer inhibits the growth of the (111) crystal facet, thereby reducing Mn dissolution and resulting in a truncated octahedral crystal structure, thus improving the electrochemical performance of the material.

[0316] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0317] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A multi-functional layered lithium manganate cathode material, characterized by, The core and the coating layer covering the surface of the core, based on the mass content distribution of the doping elements in the core, the core is divided from inside to outside into a body-doped lithium manganate matrix, an induced doping layer and a modified doping layer, the chemical general formula of the core is Li 1+a Mn 2-b-c-d M b R c X d O 4-e Z e , wherein M, Z, X, R are all doping elements, the body-doping elements of the lithium manganate matrix are M and Z, the crystal face induced elements of the induced doping layer are X, the modified doping elements of the modified doping layer are R, -0.1≤a≤0.3, 0≤b≤0.3, 0≤c≤0.3, 0≤d≤0.3, 0≤e≤0.3, at least one of b, c, d, e is not 0; the coating layer is a compound including coating element M'; The preparation method of the multifunctional layer lithium manganate positive electrode material also uses a supported crystal face inducer for further inhibiting the growth of the (111) crystal face in the spinel crystal structure of the lithium manganate and reducing the area of the (111) crystal face, so as to form the multifunctional layer lithium manganate positive electrode material including the multi-faceted spinel crystal structure of at least 26 crystal faces, and the crystal face inducer in the supported crystal face inducer includes any one or a combination of more than one of a phosphorus-containing compound, a boron-containing compound or a metal salt with at least a +5 valence state; The crystal face inducer includes any one or a combination of more than one of phytic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, boric acid, boron oxide or ammonium metavanadate; and the support in the supported crystal face inducer includes a combination of one or more than one of porous silica nanoparticles, magnesium oxide nanoparticles or activated carbon nanoparticles. The crystal faces of the multi-faceted spinel crystal structure include: 4 upper (111) crystal faces, 4 lower (111) crystal faces, (311) crystal faces sequentially separating each (111) crystal face in the upper 4 (111) crystal faces, (311) crystal faces sequentially separating each (111) crystal face in the lower 4 (111) crystal faces, (220) crystal faces or (440) crystal faces shared by the upper 4 and the lower 4, a (004) crystal face at the upper top, a (004) crystal face at the lower top, and (400) crystal faces shared by the upper 4 and the lower 4 at the corners; M is a combination of any one or more than one of Ni, Y, Co, Si, Cu, Zn, Ca, Fe, V, Al, Zr, Mg, La, Cr, Ga and Ge; and Z is a combination of any one or more than one of N, F, Cl, Br, I, B and S. X is any one or more than one of Ti, Sn, Nb, Ce, Cu, Ta, V, Mo, Ru, W, Sr and In. R is a combination of any one or more than one of La, Zr, Yb, Ba, Y, Bi, Co, W, Sr and In. The coating layer is a combination of one or more than one of oxides, fluorides, phosphates, carbonates, sulfates, nitrates, chlorides, acetates, lithium ion battery positive electrode materials and conductive organic matters, and M' is a combination of any one or more than one of B, Mg, Nb, Co, Al, Zr, Li, Ti, Ni, In, Mn, Mo and W.

2. The multi-functional layered lithium manganate cathode material of claim 1, wherein, The bulk doping elements are uniformly distributed in the core, the crystal face inducing elements are distributed in an increasing concentration from the inside to the outside of the core, and the modifying doping elements are in the modifying doping layer; In the first space from the 1 / 5 radius of the average particle size of the multifunctional layer lithium manganate positive electrode material to the surface of the multifunctional layer lithium manganate positive electrode material, the mass ratio of the sum of the masses of the two of the doping elements and the coating elements in the first space to the total mass of the two of the doping elements and the coating elements in the multifunctional layer lithium manganate positive electrode material is 0.45-0.99:

1. The second space is between the 1 / 2 radius of the average particle size of the multifunctional layer lithium manganate positive electrode material and the surface of the multifunctional layer lithium manganate positive electrode material, and the mass ratio of the modified doping element to the bulk doping element in the second space is 1:1-20; the mass ratio of the crystal face inducing element to the bulk doping element in the second space is 1:3-6; The third space is between the 2 / 3 radius of the average particle size of the multifunctional layer lithium manganate positive electrode material and the surface of the multifunctional layer lithium manganate positive electrode material, and the mass ratio of the sum of the mass of each doping element and the coating element in the third space to the total mass of the two in the multifunctional layer lithium manganate positive electrode material is 0.90-0.99:

1. The volume of the third space is greater than the volume of the second space, and the volume of the second space is greater than the volume of the first space.

3. The multi-functional layered lithium manganate cathode material of claim 1, wherein, M is a bulk doping element of manganese sites in a lithium manganate matrix, and Z is a bulk doping element of oxygen sites in the lithium manganate matrix, and the mass concentration deviation of M and Z elements at any place in the lithium manganate matrix is less than or equal to 20%; X is a crystal face inducing element in the inducing doping layer, and R is a modified doping element of oxygen sites in the modified doping layer; The conductive organic matter is any one or a combination of more than one of polyaniline, polyethylene glycol, polypyrrole, poly 3,4-ethylenedioxythiophene, and polystyrene sulfonic acid; The mass ratio of the coating element in the coating layer to the total mass of the doping elements in the core is 1:(0.5-10).

4. The multi-functional layered lithium manganate cathode material as claimed in claim 1, characterized by, The general chemical formula of the positive electrode material of lithium ion batteries includes Li 1+i (TM) x PO4 and / or Li 1+i (TM) x Lj, wherein TM is one or more transition metal elements, 0≤i≤0.3, 0≤x≤2, 1≤j≤5, L is any one or more of oxygen, anions of elements of the fifth main group, anions of elements of the sixth main group, or anions of elements of the seventh main group.

5. The multi-functional layered lithium manganate cathode material of claim 1, wherein, Based on the mass content distribution of the doping elements in the core, the modification doping layer includes a doping modification layer and a metal oxide melting layer; the chemical general formula of the lithium manganate base is Li 1+y Mn 2-x J x O4, wherein, 0≤y<0.1, 0≤x<2, J is a base doping ion; The chemical formula of the modified doped layer is Li f Mn g K' h O2, wherein 0≤f<1, 0≤g<1, 0≤h<1, and K' is a modified doping ion. wherein J is Mg 2+ , Cu 2+ , Ni 2+ , Co 2+ , Al 3+ , Zn 2+ , Fe 3+ , or Cr 3+ in any combination of one or more; K' is Sr 2 + , Ni 2+ , Ni 3+ , Yb 3+ , Y 3+ , Co 3+ , Mo 6+ , Sn 4+ , Sm 3+ , Tb 3+ , In 3+ , or W 6+ in any combination of one or more.

6. A method for preparing a multifunctional layered lithium manganate cathode material, characterized by, A method for preparing the multifunctional layer lithium manganate positive electrode material as claimed in any one of claims 1-4, comprising: S10, mixing a manganese-containing compound into a doping agent containing M elements and a supported crystal face inducing agent by a doping process, uniformly mixing the manganese-containing mixture, and pretreating the uniformly mixed manganese-containing mixture to obtain a manganese-containing crystal face inducing precursor; S11, mixing the manganese-containing crystal face inducing precursor with a doping agent containing R, X and Z elements respectively and a lithium salt, and performing first sintering to obtain a lithium manganate core; S12, coating the lithium manganate core with a coating containing M' elements, and performing second sintering to obtain the multifunctional layer lithium manganate positive electrode material.

7. The method for preparing the multifunctional layered lithium manganese oxide cathode material according to claim 6, characterized in that, The manganese-containing compound in S10 is a combination of one or more of Mn3O4, MnO2 and Mn2O3; And / or, the doping process is solid-phase doping or liquid-phase doping; And / or, the lithium salt is a combination of one or more of lithium hydroxide, lithium carbonate and lithium nitrate; And / or, the pretreatment in S10 is heating the manganese-containing mixture at 300-500°C for 2-5h; And / or, the first sintering in S11 is performed under an air or oxygen atmosphere, the temperature rising speed is 1-5°C / min, the first-stage sintering temperature is 300-600°C, the sintering time is 2-6h, the second-stage sintering temperature is 700-900°C, and the sintering time is 12-30h; And / or, the coating in S12 is performed by solid-phase coating or liquid-phase coating; And / or, the second sintering in S12 is performed under an air or oxygen atmosphere, the temperature rising speed is 1-5°C / min, the sintering temperature is 300-750°C, and the sintering time is 6-24h.

8. A method for preparing a multifunctional layered lithium manganate cathode material, characterized in that, A method for preparing the multifunctional layer lithium manganate cathode material according to any one of claims 5, comprising: S20, dissolving the soluble manganese salt, the soluble compound containing element J and the supported crystal face inducer in water to obtain a mixed metal ion solution; S21, passing gas into the mixed metal ion solution, adding a pH regulator to adjust the pH to a specified value, heating and stirring to react, aging after the reaction, and then washing, filtering and drying to obtain a manganese-containing crystal face inducer precursor; S22, mixing the manganese-containing crystal face inducer precursor with a lithium source and adding a dopant containing element K', grinding and mixing, first calcining and cooling to obtain a lithium manganate core; S23, coating the lithium manganate core with a coating containing element M', and second calcining to obtain the multifunctional layer lithium manganate cathode material; The primary particles of the multifunctional layer manganese phosphate cathode material are spherical in shape, and the thickness of the modified doped layer is 8 nm to 200 nm.

9. A lithium battery, characterized by The battery comprises a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, and the positive electrode sheet comprises the multifunctional layer lithium manganate cathode material according to any one of claims 1 to 4, or the multifunctional layer lithium manganate cathode material obtained by the preparation method according to claim 5, or the multifunctional layer lithium manganate cathode material obtained by the preparation method according to any one of claims 6 to 7, or the multifunctional layer lithium manganate cathode material obtained by the preparation method according to claim 8.

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