CN115548301A

CN115548301A - Cathode material, preparation method thereof and lithium ion battery

Info

Publication number: CN115548301A
Application number: CN202211208609.9A
Authority: CN
Inventors: 陈帅; 宋雄; 吴小珍; 杨顺毅; 黄友元
Original assignee: Better Jiangsu New Material Technology Co ltd
Current assignee: Better Jiangsu New Material Technology Co ltd
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2022-12-30

Abstract

The application provides a positive electrode material, a preparation method thereof and a lithium ion battery, and relates to the technical field of lithium ion batteries. The anode material comprises a ternary matrix material and a coating layer at least partially positioned on the surface of the ternary matrix material; the coating comprises a first coating layer and a second coating layer, wherein the second coating layer is at least partially arranged on the surface of the first coating layer, the first coating layer comprises an anionic covalent organic framework composite material, and the second coating layer comprises metal glass. The utility model provides a cathode material is through the double-deck coating that utilizes anion type covalence organic frame material and metallic glass, can show the surface residual alkali that reduces cathode material, establishes quick lithium ion transmission channel, promotes cathode material's conductivity, reduces because the specific table that the combined material coating leads to increases, is showing stability and the mechanical strength who has promoted cathode material.

Description

Cathode material, preparation method thereof and lithium ion battery

Technical Field

The application relates to the technical field of lithium ion battery anode materials, in particular to an anode material, a preparation method thereof and a lithium ion battery.

Background

For the high nickel anode material (Ni is more than or equal to 0.8), the high nickel anode material has higher theoretical reversible capacity and becomes the key point of research and development and industrialization of the field of power batteries in the future. However, the high nickel positive electrode material has a problem of high total residual lithium amount, which seriously affects battery processability. At present, polyvinylidene fluoride (PVDF) is a binder commonly used in the lithium battery industry, but the alkaline resistance of the PVDF is poor, and the PVDF can undergo an HF elimination reaction with alkali to generate double bonds, so that PVDF molecular chains are crosslinked, and gel is formed, thereby preventing coating. In view of the situation, water washing is the most mainstream method for removing residual alkali on the surface of the high-nickel ternary cathode material and further improving the processing performance at present, and the residual alkali on the surface of the high-nickel ternary material, namely the content of residual lithium, can be obviously reduced by optimizing the water washing temperature and time, the using amount and times of washing water, the drying temperature and the like, so that the processing performance of the electrode material is improved.

In practical application, water washing can bring some defects to the battery anode material, so that the surface chemical property of the anode material particles is changed, the surface of the material and electrolyte generate side reaction to form a NiO-like rock salt phase, the surface resistance of the anode material is increased, and the interface lattice strain between a layered structure and a rock salt structure is higher due to lattice mismatch, so that the electrochemical performance of the battery is reduced. These problems become more pronounced as the nickel content of the ternary material gradually increases. Generally, the higher the nickel content, the more sensitive the cathode material is to water, and the more side reactions are caused by water washing, so that the water washing process becomes less suitable. Based on the above, a new technical scheme needs to be found, which can solve the problem of residual alkali on the surface of the positive electrode material and does not affect the electrochemical performance of the positive electrode material in the battery.

Disclosure of Invention

In view of the above, the application provides a positive electrode material, a preparation method thereof, and a lithium ion battery, wherein the method of removing residual alkali on the surface of the high nickel material and generating a specific coating layer in one step by using an anionic covalent organic framework is used, so that the residual alkali on the surface of the material is effectively reduced, and the thermal stability and the cycle performance of the high nickel positive electrode material can be improved.

In order to achieve the above purpose, the technical scheme of the application is as follows:

in a first aspect, a cathode material comprises a ternary matrix material and a coating layer at least partially positioned on the surface of the ternary matrix material;

the coating comprises a first coating layer and a second coating layer, wherein the second coating layer is at least partially arranged on the surface of the first coating layer, the first coating layer comprises an anionic covalent organic framework material, and the second coating layer comprises metallic glass.

In some embodiments, the ternary matrix material has the general chemical formula Li _a Ni _x Co _y M _z O ₂ Wherein a is more than or equal to 0.95 and less than or equal to 1.1, x is more than or equal to 0.7 and less than or equal to 1, y + z is more than or equal to 0.3, x + y + z =1, M comprises at least one of Mn and Al.

In some embodiments, the anionic covalent organic framework material comprises a conjugated organic compound comprising an anionic group comprising at least one of an acidic group and an imidazole group.

In some embodiments, the anionic covalent organic framework material comprises a covalent organic framework material comprising anionic groups comprising acidic groups comprising at least one of sulfonic, carboxylic, and silicic acid groups.

In some embodiments, the metallic glass comprises a composite of a metal and boron.

In some embodiments, the metal comprises at least one of nickel, zinc, cobalt, iron, titanium, tungsten, zirconium, aluminum, magnesium, yttrium, and niobium.

In some embodiments, the positive electrode material is a spherical particulate material.

In some embodiments, the particle size of the positive electrode material is 3.5 μm to 17 μm.

In some embodiments, the specific surface area of the cathode material is 0.2m ² /g-0.7m ² /g。

In some embodiments, I of the positive electrode material ₀₀₃ /I ₀₀₄ The peak intensity ratio of (A) is 0.9 to 1.1.

In a second aspect, the present application provides a method for preparing the positive electrode material of the first aspect, including:

carrying out dry coating on a ternary matrix material and an anionic covalent organic framework material to obtain the ternary material with a first coating layer coated on the surface of the ternary matrix material, wherein the first coating layer comprises the anionic covalent organic framework material;

and carrying out wet coating on the solution containing the prepared metallic glass and the ternary material to obtain the cathode material of which the surface is coated with a second coating layer, wherein the second coating layer comprises the metallic glass.

In some embodiments, the ternary precursor and the lithium source are mixed and sintered to obtain the ternary matrix material.

In some embodiments, a two-dimensional covalent organic framework material, a solvent, and an anionic monomer are mixed and reacted to provide the anionic covalent organic framework composite.

In some embodiments, the ternary precursor comprises Ni-containing _x Co _y M _z Wherein 0.7. Ltoreq. X < 1,0 < y + z. Ltoreq.0.3, x + y + z =1, M includes Mn or Al.

In some embodiments, the lithium source comprises at least one of lithium hydroxide and lithium carbonate.

In some embodiments, the ratio of the sum of the molar contents of Ni, co, M in the ternary precursor to the molar content of Li element in the lithium source is 1: (0.95-1.1).

In some embodiments, the sintering is performed in an oxygen atmosphere having an oxygen content of 95% or more.

In some embodiments, the sintering temperature is 600-950 ℃, the time is 8-20 h, and the temperature rise speed in the range of 450-650 ℃ is 0.5-3 ℃/min.

In some embodiments, the sintering further comprises, after: and (3) crushing the ternary matrix material to obtain particles with the particle size of 3.5-17 microns.

In some embodiments, the molar ratio of the two-dimensional covalent organic framework material to the anionic monomer is (0.1-1): (0.5-2).

In some embodiments, the two-dimensional covalent organic framework material comprises at least one of an aldehyde, a catechol, a hydroxy arene, an alkoxide, an amine, and a hydrazine.

In some embodiments, the aldehyde comprises at least one of trimesic aldehyde, 1,3, 5-benzenetricarboxylic aldehyde, and trioxymethylenephenol, the hydroxyaromatic hydrocarbon comprises at least one of 9-10-dimethyl-2, 3,6, 7-tetrahydroxyanthracene and hexahydrotriphenylene, and the amine comprises at least one of diaminosulfonic acid and diaminobiphenyl dicarboxylic acid.

In some embodiments, the anionic monomer comprises at least one of 1-vinylimidazole, 1-methylimidazole, 2-nitroimidazole, 1-imidazoleacetic acid, 4-imidazole, 4-hydroxymethylimidazole, 1-acetylimidazole, trimethyl borate, triphenylboron, diphenylboronic acid, benzenesulfonic acid, sulfamic acid, 2, 5-diaminobenzenesulfonic acid, diaminobenzenedisulfonic acid, and sodium methylsilicate, potassium methylsilicate, and ethyl silicate.

In some embodiments, the solvent comprises at least one of DMF, tetrahydrofuran, methanol, acetone, n-hexane.

In some embodiments, the reaction comprises stirring under an atmosphere of an inert gas, the frequency of stirring being from 10Hz to 50Hz.

In some embodiments, the reaction is at a temperature of 100 ℃ to 120 ℃ for a time of 60h to 84h.

In some embodiments, after the reaction, the reaction further comprises filtering, washing and drying, wherein the drying temperature is 60-100 ℃, and the drying time is 5-20 h.

In some embodiments, the solution for preparing the metallic glass comprises a mixed solution obtained by stirring a metal nitrate, a compound containing an N element, and an organic solvent, wherein the N element is a non-metallic element.

In some embodiments, the metal in the metal nitrate comprises at least one of nickel, zinc, cobalt, iron, titanium, tungsten, zirconium, aluminum, magnesium, yttrium, and niobium.

In some embodiments, the boron hydride compound comprises NaBH ₄ And KBH ₄ At least one of (a).

In some embodiments, the organic solvent comprises at least one of absolute ethanol, diethyl ether, methanol, acetone, pentane, hexane.

In some embodiments, the molar ratio of the metal nitrate, the N-containing compound, and the organic solvent is (0.08-0.25): (0.5-1): (4-10).

In some embodiments, the wet coating comprises: and slowly dripping the solution containing the metallic glass into the ternary material for stirring.

In some embodiments, the dropping is at a rate of 0.5L/min to 3L/min.

In some embodiments, the wet cladding is performed in a single cone.

In some embodiments, the wet coating is dried for 1 to 4 hours.

In some embodiments, the mass ratio of the ternary matrix material to the anionic covalent organic framework material is (0.9-0.99): (0.1-0.01).

In a third aspect, the present application further provides a lithium ion battery, including the positive electrode material described in the first aspect or the positive electrode material prepared by the preparation method described in the second aspect.

The beneficial effect of this application:

according to the cathode material, the anion covalent organic framework composite material is coated on the surface of the ternary matrix material, the covalent organic framework material has a large conjugated system of delocalized pi electrons and has excellent chemical and thermodynamic stability, and after the anion covalent organic framework composite material is further formed, a positive electric channel can be constructed in the formed composite material because an anion monomer is negative, a rapid lithium ion transmission channel is established, and the conductivity of the cathode material is improved. In addition, the outermost layer of the metallic glass has ultrahigh ductility and fluidity, so that the gap of the organic coating layer can be effectively filled, and even the metallic glass penetrates into the interior of the organic coating layer and enters primary particles of the material; the composite material also has super-strong stability, can effectively isolate the surface of the anode material and the side reactions of the coating layer and the electrolyte, and remarkably reduces the increase of a specific surface caused by the coating of the covalent organic framework composite material, thereby remarkably improving the stability and the mechanical strength of the anode material.

According to the preparation method of the cathode material, an anion covalent organic framework composite material system is constructed by utilizing an in-situ reaction, and meanwhile, the composite material and the ternary matrix material are coated in a dry method, so that the controllable preparation of the coating layer is realized, the process is simple, the cost is low, and the preparation method is suitable for large-scale production. In addition, the coating layer formed by dry coating has stronger granular sensation, and can effectively fill the gap by performing wet coating with the metallic glass solution with ultrahigh ductility and fluidity, thereby obviously reducing the specific surface area of the anode material and improving the stability and the continuous strength of the anode material.

According to the lithium ion battery, the processing performance and the safety performance of the lithium ion battery are effectively improved, and the rate capability and the cycle performance of the battery are enhanced by using the cathode material or the cathode material prepared by the preparation method.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope of the present invention.

FIG. 1 is a high power SEM image of the high nickel cathode material of example 1;

fig. 2 is a graph of capacity retention rate of the batteries of example 1 and comparative example 1 after 50 cycles.

Detailed Description

The terms as used herein:

"by 8230; \ 8230; preparation" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of 8230% \8230comprises" excludes any unspecified elements, steps or components. If used in a claim, this phrase shall render the claim closed except for the materials described except for those materials normally associated therewith. When the phrase "consisting of 8230' \8230"; composition "appears in a clause of the subject matter of the claims and not immediately after the subject matter, it defines only the elements described in the clause; no other elements are excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or range defined by a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4," "1 to 3," "1 to 2 and 4 to 5," "1 to 3 and 5," and the like. When a range of values is described herein, unless otherwise specified, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

In these examples, the parts and percentages are by mass unless otherwise indicated.

"part by mass" means a basic unit of measure indicating a mass ratio of a plurality of components, and 1 part may represent an arbitrary unit mass, for example, 1g or 2.689 g. If the parts by mass of the component A are a parts and the parts by mass of the component B are B parts, the mass ratio of the component A to the component B is expressed as a: b. alternatively, the mass of the A component is aK and the mass of the B component is bK (K is an arbitrary number, and represents a multiple factor). It is unmistakable that, unlike the parts by mass, the sum of the parts by mass of all the components is not limited to 100 parts.

"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).

The cathode material comprises a ternary matrix material and a coating layer at least partially positioned on the surface of the ternary matrix material; the coating comprises a first coating layer and a second coating layer at least partially positioned on the surface of the first coating layer, the first coating layer comprises an anionic covalent organic framework composite material, and the second coating layer comprises metallic glass.

By coating the anion covalent organic framework composite material on the surface of the ternary matrix material, the covalent organic framework material has a large conjugated system of delocalized pi electrons and has excellent chemical and thermodynamic stability, and after the anion covalent organic framework composite material is further formed, because an anion monomer is negatively charged, a positive electric channel can be constructed in the formed composite material, a rapid lithium ion transmission channel is established, and the conductivity of the cathode material is improved. In addition, the outermost layer of the metallic glass has ultrahigh ductility and fluidity, so that the gap of the organic coating layer can be effectively filled, and even the metallic glass penetrates into the interior of the organic coating layer and enters primary particles of the material; the composite material also has super-strong stability, can effectively isolate the surface of the anode material and the side reaction of the coating layer and the electrolyte, and remarkably reduces the increase of a specific surface caused by the coating of the covalent organic framework composite material, thereby remarkably improving the stability and the mechanical strength of the anode material; the first coating layer and the second coating layer have a synergistic effect, and the stability of the cathode material is improved.

In some embodiments, the ternary matrix material has the general chemical formula Li _a Ni _x Co _y M _z O ₂ Wherein a is more than or equal to 0.95 and less than or equal to 1.1, x is more than or equal to 0.7 and less than or equal to 1, y + z is more than or equal to 0.3, x + y + z =1, M comprises Mn or Al. It can be understood that the ternary material of nickel cobalt manganese or nickel cobalt aluminum is used as the positive active material to prepare the lithium ion battery, and the battery has higher energy density, better cycle performance and lower cost than the common lithium iron phosphate battery.

In some embodiments, an anionic covalent organic framework material comprises a conjugated organic compound comprising an anionic group comprising at least one of an acidic group and an imidazole group; the acid groups and the imidazole groups can react with residual alkali on the surface of the anode material, so that the residual alkali content on the surface of the anode material is reduced.

The anionic covalent organic framework material is prepared by reacting a two-dimensional covalent organic framework material with an anionic monomer, namely, performing coordination reaction on the covalent organic framework material and an anionic group in the anionic monomer, and finally obtaining the anionic covalent organic framework material modified by a specific acidic group. Such as schiff base reactions of phloroglucinol and sulphonic acids, condensation reactions of hydroxyanthracenes and methyl silicates, transesterification reactions of gamma-cyclodextrins and fatty acids.

In some embodiments, the acidic group comprises at least one of a sulfonic acid group, a carboxylic acid group, and a silicic acid group.

The covalent organic framework material is mainly constructed by boric acid dehydration trimerization, condensation of boric acid and catechol compound, cyano self-polymerization, schiff base reaction (dehydration condensation reaction of aldehyde and amine, hydrazine, hydrazone, etc.), and the like. The organic small molecular units are precisely connected through covalent bond atoms to form a material with a periodic porous framework structure, namely the covalent organic framework material. In a two-dimensional covalent organic framework material, two-dimensional polygonal sheets are generally formed by covalent bond connection, and the sheets can be stacked layer by layer to form a periodic pi array, so that the carrier transmission in the stacking direction can be promoted.

In some embodiments, the metallic glass comprises a composite of a metal comprising at least one of nickel, zinc, cobalt, iron, titanium, tungsten, zirconium, aluminum, magnesium, yttrium, and niobium, and boron.

It is understood that metallic glass is an amorphous alloy, and metallic glass is a metal atom and a light element nonmetal bonded by a metal covalent bond.

In the cathode material, the anionic covalent organic framework composite material is coated on the surface of the ternary matrix material to form a first coating layer. Specifically, the acid groups on the surface of the anionic covalent organic framework composite material are utilized to react with residual alkali such as OH on the surface of the cathode material ^- And CO ₃ ^2- And a chemical bonding reaction is generated, so that the connection strength between the first coating layer and the ternary matrix material is enhanced, and the surface residual alkali of the ternary cathode material is further remarkably reduced.

Furthermore, the problem of low conductivity of a single material is solved by constructing an anionic covalent organic framework composite material system. The two-dimensional covalent organic framework material has a large conjugated system of delocalized pi electrons and has excellent chemical and thermodynamic stability, and as an organic functional sensitizing material with excellent performance, the two-dimensional covalent organic framework material can be stably coupled with anion groups through covalent or supermolecular action, and the anion groups are negative, so that the anion groups can construct positive channels in the annular structure of the organic framework, the transmission of lithium ions is facilitated, and the transmission performance of the lithium ions is improved. Furthermore, the anion covalent organic framework composite material is coated on the surface of the ternary matrix material, so that a rapid lithium ion transmission channel can be established, and the conductivity of the cathode material is improved.

In addition, the metallic glass of the second coating layer has ultrahigh ductility and fluidity, and can effectively fill the gap of the first coating layer and even enter the primary particles of the material from the inside. This application chooses for use metallic glass as the material of second cladding layer, except that it has super high ductility and mobility, still because metallic glass possesses superstrong stability, can effectively keep apart the positive electrode material surface and the coating and the side reaction of electrolyte, is showing to reduce because the ratio table that the cladding of covalence organic frame combined material leads to increases to the stability and the mechanical strength of positive electrode material have been showing and have been promoted. The metallic glass has excellent oxidation resistance even at a high temperature of about 900 ℃, and forms a dense healing passivation layer at an interface even if the metallic glass reacts with oxygen, without affecting the performance of the interior material, and also preventing the oxidation of the interior material by the external environment.

In some embodiments, the positive electrode material comprises a spherical particulate material. Further, the particle diameter of the positive electrode material is 3.5 μm to 17 μm, and may be, for example, 3.5 μm, 5 μm, 7 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, 17 μm, or any value between 3.5 μm to 17 μm.

In some embodiments, the specific surface area of the cathode material is 0.2m ² /g-0.7m ² Per g, may be, for example, 0.2m ² /g、0.3m ² /g、0.4m ² /g、0.5m ² /g、0.6m ² /g、0.7m ² Is/g or 0.2m ² /g-0.7m ² Any value between/g.

In some embodiments, I of the positive electrode material ₀₀₃ /I ₀₀₄ The peak intensity ratio of (a) is 0.9 to 1.1, and may be, for example, 0.9, 0.95, 1.0, 1.05, 1.1 or an arbitrary value between 0.9 and 1.1.

The application also provides a preparation method of the cathode material, which comprises the following steps:

(1) Mixing and sintering the ternary precursor and a lithium source to obtain a ternary matrix material;

(2) Mixing and reacting a two-dimensional covalent organic framework material, a solvent and an anionic monomer to obtain an anionic covalent organic framework composite material with an acid group on the surface;

(3) Carrying out dry coating on the ternary matrix material and the anionic covalent organic framework composite material to obtain a ternary material with a first coating layer coated on the surface of the ternary matrix material;

(4) And carrying out wet coating on the solution containing the metal glass and the ternary material to obtain the cathode material with a second coating layer coated on the surface of the ternary material.

In some embodiments, the stepsThe ternary precursor in step (1) comprises Ni _x Co _y M _z Wherein 0.7. Ltoreq. X < 1,0 < y + z. Ltoreq.0.3, x + y + z =1, M includes Mn or Al.

In some embodiments, the lithium source comprises at least one of lithium hydroxide and lithium carbonate, more preferably lithium hydroxide.

In some embodiments, the ratio of the sum of the molar contents of Ni, co, M in the ternary precursor to the molar content of Li element in the lithium source is 1: (0.95-1.1), for example, may be 1:0.95, 1:0.98, 1:1. 1:1.02, 1:1.05, 1:1.08, 1:1.1 or 1: (0.95-1.1). More preferably, the molar ratio is 1:1.02.

in some embodiments, the sintering in step (1) is performed in an oxygen atmosphere having an oxygen content of 95% or more.

In some embodiments, the sintering temperature is 600 ℃ to 950 ℃, for example, can be 600 ℃, 700 ℃, 800 ℃, 900 ℃, 950 ℃ or any value between 600 ℃ to 950 ℃, and the sintering time is 8h to 20h, for example, can be 8h, 10h, 12h, 14h, 16h, 18h, 20h or any value between 8h to 20h.

It should be noted that, when the temperature rise sintering is performed, when the temperature reaches the temperature range of 450 ℃ -650 ℃, the temperature rise speed needs to be ensured to be 0.5 ℃/min-3 ℃/min, for example, it can be any value between 0.5 ℃/min, 1 ℃/min, 1.5 ℃/min, 2 ℃/min, 2.5 ℃/min, 3 ℃/min or between 0.5 ℃/min-3 ℃/min. If the temperature rise speed is too high, elements in the prepared ternary matrix material are easily uneven, and the lithium content in the ternary matrix material is too small, so that the performance of the anode material is influenced; and if the temperature rise speed is too low, the production efficiency is greatly reduced, the production cost is increased, and the resource waste is easily caused.

In some embodiments, step (1) requires that all raw materials be ground and uniformly pulverized before sintering, and then sintering is performed at elevated temperature, which is also to ensure that all raw materials are sufficiently reacted. Also included after sintering are: the ternary matrix material obtained is ground to a particle size of 3.5 to 17 μm, which may be, for example, 3.5 to 5 μm, 7 to 9 μm, 10 to 12 μm, 14 to 15 μm, 17 μm or any value between 3.5 to 17 μm.

In order to prevent the properties of the sintered ternary matrix material from being changed due to the influence of the outside, the sintered material is generally stored in a PE bag and sealed by an aluminum plastic film.

It should be noted that step 1) may be omitted, and the ternary matrix material may be purchased directly from the market.

In some embodiments, the solvent in step (2) comprises at least one of DMF, tetrahydrofuran, methanol, acetone, n-hexane. The solvent is used primarily to dissolve the anionic monomer so that the anionic groups in the anionic monomer can react with the covalent organic framework.

In some embodiments, the molar ratio of the two-dimensional covalent organic framework material to the anionic monomer is (0.1-1): (0.5-2), for example, it may be 0.1:0.5, 0.3:0.5, 0.5:1. 0.8: 1. 1:1.5 or is (0.1-1): (0.5-2), more preferably 0.5:1.

in some embodiments, the reaction in step (2) comprises stirring under an inert gas atmosphere, wherein the stirring frequency is 10Hz to 50Hz, for example, 10Hz, 20Hz, 30Hz, 40Hz, 50Hz or any value between 10Hz and 50Hz, and more preferably 30Hz.

In some embodiments, the temperature of the reaction in step (2) is 100 ℃ to 120 ℃, for example, may be 100, 110, 120, or any value between 100 ℃ to 120 ℃, and the reaction time is 60h to 84h, for example, may be 60h, 68h, 72h, 80h, 84h, or any value between 60h to 84h.

In some embodiments, after the reaction is finished, filtering, washing and drying are further carried out to obtain the solid anionic covalent organic framework composite material. It is noted that the drying is carried out at a temperature of 60 ℃ to 100 ℃ for a period of 5h to 20h, more preferably 10h. If the drying temperature is too high or the drying time is too long, the performance of the composite material is easily influenced, and particularly the stability of a conjugated system or an anionic group in the composite material can be influenced, so that an electron/ion transmission channel is eliminated, and the conductivity of the material is reduced.

In some embodiments, the mass ratio of the ternary matrix material to the anionic covalent organic framework material in step (3) is (0.9-0.99): (0.1-0.01), for example, it may be 0.9:0.1, 0.93:0.07, 0.95:0.05, 0.97:0.03, 0.99:0.01 or is (0.9-0.99): (0.1-0.01), more preferably 0.96:0.04.

In some embodiments, the aldehydes include, but are not limited to, trimesic aldehyde, 1,3, 5-benzenetricarboxylic aldehyde, trialdehyde-resorcinol; hydroxy aromatic hydrocarbons include 9-10-dimethyl-2, 3,6, 7-tetrahydroxyanthracene, hexahydroxytriphenylene; the amine includes diaminosulfonic acid, diaminobiphenyldicarboxylic acid, etc.

In some embodiments, the anionic monomer comprises at least one of 1-vinylimidazole, 1-methylimidazole, 2-nitroimidazole, 1-imidazoleacetic acid, 4-imidazole, 4-hydroxymethylimidazole, 1-acetylimidazole, trimethylborate, triphenylboron, diphenylboronic acid, benzenesulfonic acid, sulfamic acid, 2, 5-diaminobenzenesulfonic acid, diaminobenzenedisulfonic acid, and sodium methylsilicate, potassium methylsilicate, ethyl silicate;

in the step (3), when dry coating is performed, a dry coating machine may be selected to perform mixed coating on the ternary matrix material and the anionic covalent organic framework material particles to obtain a ternary material with the surface coated with the first coating layer anionic covalent organic framework material.

When the first coating layer is coated, secondary heat treatment is not needed, so that a conjugated system in the covalent organic framework material can be effectively reserved, efficient electron/ion transmission channels on the surface of the material can be reserved, the conductivity of electrons and lithium ions of the anode material is well improved, and the rate capability and the cycle performance of the anode material are remarkably enhanced.

In some embodiments, the solution for preparing metal glass in step (4) includes a mixed solution obtained by stirring metal nitrate, borohydride and organic solvent.

In some alternative embodiments, the metal of the metal nitrate comprises at least one of nickel, zinc, cobalt, iron, titanium, tungsten, zirconium, aluminum, magnesium, yttrium, and niobium.

In some alternative embodiments, the boron hydride compound comprises NaBH ₄ And KBH ₄ At least one of (1).

In some alternative embodiments, the organic solvent comprises at least one of absolute ethanol, diethyl ether, methanol, acetone, pentane, hexane.

In some alternative embodiments, the molar ratio of metal nitrate, borohydride, and organic solvent is (0.08-0.25): (0.5-1): (4-10), for example, may be 0.08:0.5: 4. 0.1:0.5: 6. 0.2:0.8: 8. 0.25:1:10 or is (0.08-0.25): (0.5-1): (4-10), more preferably 0.1:1:6.

in some embodiments, the wet coating in step (4) comprises: and slowly dripping the solution containing the metal glass into the ternary material and stirring.

In some alternative embodiments, the dropping rate is 0.5L/min to 3L/min, for example, 0.5L/min, 1L/min, 1.5L/min, 2L/min, 2.5L/min, 3L/min, or any value between 0.5L/min and 3L/min, more preferably 1L/min.

In some embodiments, the wet coating in step (4) is performed in a single cone. Further, after the coating is finished, the coating can be dried in a single cone for 1h to 4h, for example, 1h, 2h, 3h, 4h or any value between 1h and 4h, and more preferably 2h.

In the wet coating process used in step (4), the dry-coated coating layer has a strong granular feel, and the wet-coated metallic glass can effectively fill the gaps, completely cover the surfaces of the secondary particles of the ternary positive electrode material, and can be injected between the primary particles of the positive electrode material in a metal fluid state with a zero equilibrium contact angle.

The second clad metallic glass of the present application can be synthesized at room temperature, thereby eliminating the complexity of subsequent high-temperature treatment, and the metallic glass has excellent oxidation resistance even at high temperatures of around 900 ℃. Even if the metallic glass reacts with oxygen, a dense, healing passivation layer is formed at the interface. In addition, metallic glass is widely used for coating metal parts to improve corrosion resistance and wear resistance, so that it is not easily chipped or broken on a nano-scale and has excellent mechanical properties.

The application also provides a lithium ion battery, and the preparation method of the lithium ion battery comprises the following steps: and uniformly mixing the prepared positive electrode material with a conductive agent and a binder according to a certain proportion, adding a solvent to form uniform slurry, uniformly coating the slurry on an aluminum foil, performing vacuum drying to obtain a positive electrode plate, and assembling the prepared positive electrode plate and other components in a battery to obtain the lithium ion battery.

Embodiments of the present invention will be described in detail below with reference to specific examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available.

Example 1

The application provides a positive electrode material, and a preparation method of the positive electrode material comprises the following steps:

1) LiOH and ternary material nickel cobalt manganese precursor Ni _0.85 Co _0.1 Mn _0.05 (OH) ₂ According to a molar ratio of 1.02:1, grinding and grinding;

2) Heating the mixture obtained in the step 1) in a muffle furnace at a speed of 2 ℃/min, wherein the temperature is increased within a range of 500-600 ℃ at a speed of 1 ℃/min, controlling the sintering temperature at 750 ℃, and sintering for 15h;

3) Crushing the sintered nickelic ternary positive electrode material in the step 2) to a particle size of about 12 microns, storing the crushed material in a PE bag, and sealing the PE bag by using an aluminum plastic film;

4) Preparing a stirring tank, adding 50g of DMF (dimethyl formamide), then weighing 2g of gamma-cyclodextrin (gamma-CD) (organic framework material) and 1g of trimethylborate, adding into the stirring tank, stirring at 30Hz at 110 ℃, reacting for 72 hours, cooling, filtering, washing, and drying for 10 hours to obtain anion covalent organic framework material particles;

5) Preparing a dry coating machine, and mixing and coating 96g of the high-nickel ternary material obtained in the step 3) and 4g of the anionic covalent organic framework material particles obtained in the step 4) to obtain a coated ternary cathode material;

6) A stirred tank was prepared, with a ratio of 0.1:1:6, adding cobalt nitrate and NaBH ₄ And absolute ethyl alcohol, and stirring vigorously;

7) And (3) putting the coated ternary material obtained in the step 5) into a single cone, slowly adding the solution obtained in the step 6), vigorously stirring again, and drying for 2 hours to obtain a high-nickel ternary cathode material finished product.

The ternary matrix material in the high-nickel ternary cathode material obtained in the embodiment is Li _1.02 Ni _0.85 Co _0.1 Mn _0.05 O ₂ The first coating layer anion covalent organic framework material is iCOF, the second coating layer metal glass is CoB, and the first coating layer anion covalent organic framework material is specifically expressed as iCOF-CoB: li _1.02 Ni _0.85 Co _0.1 Mn _0.05 O ₂ (ii) a As shown in figure 1, the high-nickel ternary cathode material is in the form of spherical particles, the average particle diameter of the cathode active material is 11.04 mu m, and the specific surface area is 0.596m ² /g。

Example 2

The same as example 1, except that: in step 6), the ratio of 0.1:1:6 adding zirconium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary positive electrode material obtained in the embodiment is iCOF-ZrB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles, and the specific surface area is 0.584m ² /g。

Example 3

The same as example 1, except that: step 6) according to a ratio of 0.1:1:6 adding magnesium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary cathode material obtained in the embodiment is iCOF-MgB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles with the specific surface area of 0.566m ² /g。

Example 4

The same as example 1, except that: step 6) according to a ratio of 0.1:1:6 adding titanium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary positive electrode material obtained in the embodiment is iCOF-TiB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The cathode material is spherical particles, has an average particle size and a specific surface area of 0.554m ² /g。

Example 5

The same as example 1, except that: in step 4), 2g of 9,10-dimethyl-2,3,6,7-tetrahydroxyanthracene and 0.2g of sodium methylsilicate were taken.

The high-nickel ternary cathode material obtained in the embodiment is iCOF-CoB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles with the specific surface area of 0.633m ² /g。

Example 6

The same as example 5, except that: step 6) according to a ratio of 0.1:1:6 adding zirconium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary positive electrode material obtained in the embodiment is iCOF-ZrB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles, and the specific surface area is 0.612m ² /g。

Example 7

The same as example 5, except that: step 6) according to a ratio of 0.1:1:6 adding magnesium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary cathode material obtained in the embodimentIs iCOF-MgB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles, and the specific surface area is 0.603m ² /g。

Example 8

The same as example 5, except that: step 6) according to a ratio of 0.1:1:6 adding titanium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary positive electrode material obtained in the embodiment is iCOF-TiB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles, and the specific surface area is 0.612m ² /g。

Example 9

The same as example 1, except that: in step 4), 2g of 1,3, 5-trimethylacylphloroglucinol and 0.2g of aminophthalic acid are taken.

The high nickel ternary positive electrode material obtained in this example is an iCOF-CoB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The cathode material is spherical particles, and the specific surface area is 0.678m ² /g。

Example 10

The same as example 9, except that: step 6) according to a ratio of 0.1:1:6 adding zirconium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary positive electrode material obtained in the embodiment is iCOF-ZrB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles with the specific surface area of 0.687m ² /g。

Example 11

The same as in example 9, except that: step 6) according to a ratio of 0.1:1:6 adding magnesium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary cathode material obtained in the embodiment is iCOF-MgB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical granular and has a specific surface area of 0.661m ² /g。

Example 12

The same as in example 9, except that: step 6) according to a ratio of 0.1:1:6, adding titanium nitrate and NaBH ₄ And absolute ethyl alcohol.

The high-nickel ternary positive electrode material obtained in the embodiment is iCOF-TiB: li _1.02 Ni _0.8 Co _0.1 Mn _0.1 O ₂ (ii) a The anode material is spherical particles, and the specific surface area is 0.692m ² /g。

Comparative example 1

The same as example 1, except that: after drying in the step 7), calcining the obtained solid for 6h at 500 ℃ in an oxygen atmosphere, and obtaining the high-nickel anode ternary material with the specific surface area of 0.452m after the reaction is finished ² /g。

Comparative example 2

The same as example 1, except that: in the DMF in the step 4), only 2g of flexible gamma-cyclodextrin (gamma-CD) is weighed and added into a stirring tank, stirring is carried out at 110 ℃ at 30Hz, and drying is carried out for 10 hours to obtain the covalent organic framework material with the specific surface area of 0.503m ² /g。

Comparative example 3

The same as example 1, except that: directly obtaining a ternary cathode material finished product with the specific surface area of 3.503m after the step 5) is finished ² /g。

Comparative example 4

The same as in example 1, except that: continuously adding 2g of cobalt oxide particles into the dry coating machine in the step 6) for dry coating to obtain a high-nickel ternary cathode material finished product with the specific surface area of 2.398m ² /g。

The test method comprises the following steps:

and (3) particle size testing:

a Mastersizer model 3000 laser particle size analyzer from malvern instruments ltd, uk was used.

The observation and test method for the microscopic morphology of the powder particles of the anode material comprises the following steps:

the sample surface morphology was observed for the material using a Tecnai G2F 20 model High Resolution Scanning Electron Microscope (HRSEM).

Specific surface area test:

the nitrogen adsorption specific surface area analysis test was performed by a Tri Star model II specific surface area and pore analyzer of Micromeritics, USA, and was calculated by the BET (Brunauer Emmett Teller) method.

The residual alkali test method comprises the following steps:

dispersing a certain amount of cathode material in deionized water, stirring and dispersing for a certain time (more than 30 minutes), then filtering to obtain supernatant, carrying out acid-base titration by using calibrated dilute hydrochloric acid, respectively using phenolphthalein and methyl orange as indicators of titration end points to obtain two titration end points, and calculating to obtain the content of LiOH and Li2CO3 (or LiHCO 3) and the total residual alkali content. The finished cathode materials of example 1, comparative example 1 and comparative example 2 were subjected to a carbonate content test, and the test results are shown in table 1.

The electrochemical performance of the prepared anode material is evaluated by adopting a button type half cell, and the specific method is as follows: weighing a positive electrode active material, SP and polyvinylidene fluoride (PVDF) according to a mass ratio of 8. A lithium sheet having a diameter of 16mm was used as a negative electrode sheet, a Celgard polyethylene PP film was used as a separator, and a solution of LiPF6 having a concentration of 1mol/L (DEC/EC volume ratio 1.

A LAND battery test system is adopted to test the discharge capacity and the first-turn charge-discharge efficiency performance at 25 ℃ and 3.0V-4.3V, the reference capacity is set to be 200mA/g, and the 1C corresponding current density is 200mA/g. The test results are shown in Table 2.

TABLE 1

	Carbonate content (pp) of the finished productm)
		Example 1	3780
Comparative example 1	6010
		Comparative example 2	5401

From the results of table 1, it can be found that: comparative example 1 is a ternary positive electrode material obtained by performing secondary sintering in an oxygen atmosphere, and lithium carbonate on the surface of the positive electrode material prepared by this method is higher than that of example 1 because the organic polymer material in the coating layer reacts with lithium secondarily at a high temperature to generate lithium carbonate. Comparative example 2 only uses covalent organic framework for modification, there are not enough acidic groups to convert surface lithium hydroxide and lithium carbonate, and only physical coating is used, so that the surface residual alkali is still high.

The positive electrode materials of examples 1 to 12 and comparative examples 1 to 4 were fabricated into batteries having the same specifications, and electrochemical performance tests were performed on the batteries, and table 2 shows the test results of the batteries fabricated in examples 1 to 12 and comparative examples 1 to 4 under different test conditions. Fig. 2 shows capacity retention rate curves of the batteries prepared in example 1 and comparative example 1 after 50 cycles.

TABLE 2

From the results in table 2, it can be found that: examples 1 to 12 different metal elements were selectedThe metal glass coating layer formed by the element and the anionic covalent organic framework composite material coating layer prepared by different raw materials have little influence on the electrochemical performance of the battery. However, in comparative example 1, the organic framework structure of the surface coating layer is damaged due to the secondary sintering (the specific surface area is obviously reduced), so that the structural stability of the cathode material is reduced, and the cycle retention rate is reduced relative to that of example 1; in comparative example 2, the surface transmission performance of lithium ions is obviously reduced due to the absence of the anionic monomer, the ion transmission channel is absent, the fastening capacitance is obviously reduced, and compared with example 1, the capacity of comparative example 2 is reduced by 5.8mAh/g; in comparative example 3, the surface of the material is coated by the anionic covalent organic framework composite material alone, so that the specific surface area of the material is remarkably increased (reaching 3.503 m) ² The contact area with the electrolyte is increased, and the surface structure is obviously damaged and side reactions are increased after a long-time circulation process, so that the circulation is obviously reduced; comparative example 4 is a high nickel ternary material modified by metal oxide instead of metallic glass, but compared with comparative example 3, the method does not significantly reduce the specific surface of the material (2.398 m) ² /g), because the metal oxide particles cannot fill the gaps of the ion-conducting covalent organic framework layer, the surface coating is loose, the surface result is damaged in the process of multiple cycles, and the cycle performance is continuously reduced (90.1%) to be close to the level of comparative example 3.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Moreover, those of skill in the art will appreciate that while some embodiments herein include some features included in other embodiments, not others, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims

1. The positive electrode material is characterized by comprising a ternary matrix material and a coating layer at least partially positioned on the surface of the ternary matrix material;

the coating layer comprises a first coating layer and a second coating layer at least partially positioned on the surface of the first coating layer, the first coating layer comprises an anionic covalent organic framework material, and the second coating layer comprises metal glass.

2. The positive electrode material according to claim 1, wherein at least one of the following characteristics a-e is satisfied:

a. the chemical general formula of the ternary matrix material is Li _a Ni _x Co _y M _z O ₂ Wherein a is more than or equal to 0.95 and less than or equal to 1.1, x is more than or equal to 0.7 and less than or equal to 1, y + z is more than 0 and less than or equal to 0.3, and x + y + z=1, M comprises at least one of Mn and Al;

b. the anionic covalent organic framework material comprises a covalent organic framework material comprising anionic groups comprising at least one of acidic groups and imidazole groups;

c. the anionic covalent organic framework material comprises a covalent organic framework material comprising anionic groups, the anionic groups comprising acidic groups, the acidic groups comprising at least one of sulfonic acid groups, carboxylic acid groups and silicic acid groups;

d. the metallic glass comprises a composite of a metal and boron;

e. the metal includes at least one of nickel, zinc, cobalt, iron, titanium, tungsten, zirconium, aluminum, magnesium, yttrium, and niobium.

3. The positive electrode material according to claim 1 or 2, wherein at least one of the following characteristics a-d is satisfied:

a. the positive electrode material is a spherical granular material;

b. the particle size of the positive electrode material is 3.5-17 mu m;

c. the specific surface area of the positive electrode material is 0.2m ² /g-0.7m ² /g；

d. I of the positive electrode material ₀₀₃ /I ₀₀₄ The peak intensity ratio of (A) is 0.9 to 1.1.

4. A method for preparing a positive electrode material, comprising:

carrying out dry coating on a ternary matrix material and an anionic covalent organic framework material to obtain a ternary material of which the surface is coated with a first coating layer, wherein the first coating layer comprises the anionic covalent organic framework material;

5. The method for producing a positive electrode material according to claim 4, wherein at least one of the following characteristics a-b is satisfied:

a. mixing and sintering a ternary precursor and a lithium source to obtain the ternary matrix material;

b. and mixing and reacting the two-dimensional covalent organic framework material, a solvent and an anionic monomer to obtain the anionic covalent organic framework composite material.

6. The method for producing a positive electrode material according to claim 5, wherein at least one of the following characteristics a to n is satisfied:

a. the ternary precursor comprises Ni _x Co _y M _z By oxidation ofOr a hydroxide, wherein 0.7 < x < 1,0 < y + z < 0.3, x + y + z =1, M includes at least one of Mn and Al;

b. the lithium source comprises at least one of lithium hydroxide and lithium carbonate;

c. the ratio of the sum of the molar contents of Ni, co and M in the ternary precursor to the molar content of Li in the lithium source is 1: (0.95-1.1);

d. the sintering is carried out in an oxygen atmosphere, and the content of oxygen in the oxygen atmosphere is more than or equal to 95 percent;

e. the sintering temperature is 600-950 ℃, the time is 8-20 h, and the temperature rise speed in the range of 450-650 ℃ is 0.5-3 ℃/min;

f. after the sintering, the method further comprises the following steps: crushing the ternary matrix material to obtain particles with the particle size of 3.5-17 microns;

g. the molar ratio of the two-dimensional covalent organic framework material to the anionic monomer is (0.1-1): (0.5-2);

h. the two-dimensional covalent organic framework material comprises at least one of aldehyde, catechol, hydroxy aromatic hydrocarbon, alkoxy compound, amine and hydrazine;

i. the two-dimensional covalent organic framework material comprises at least one of trimesic aldehyde, 1,3, 5-benzenetricarboxylic aldehyde, trialdehyde-resorcinol, 9-10-dimethyl-2, 3,6, 7-tetrahydroxyanthracene, hexahydroxy triphenylene, diamino sulfonic acid and diamino biphenyl dicarboxylic acid;

j. the anionic monomer comprises at least one of 1-vinylimidazole, 1-methylimidazole, 2-nitroimidazole, 1-imidazoleacetic acid, 4-imidazole, 4-hydroxymethylimidazole, 1-acetylimidazole, trimethyl borate, triphenylboron, diphenyl boric acid, benzenesulfonic acid, sulfamic acid, 2, 5-diaminobenzenesulfonic acid, diaminobenzene disulfonic acid and sodium methylsilicate, potassium methylsilicate and ethyl silicate;

k. the solvent comprises at least one of DMF, tetrahydrofuran, methanol, acetone and n-hexane;

the reaction comprises stirring in an inert gas atmosphere, wherein the stirring frequency is 10Hz-50Hz;

m, the reaction temperature is 100-120 ℃, and the reaction time is 60-84 h;

and n, after the reaction, filtering, washing and drying, wherein the drying temperature is 60-100 ℃, and the drying time is 5-20 h.

7. The method for producing a positive electrode material according to claim 4, wherein at least one of the following characteristics a to e is satisfied:

a. the solution for preparing the metal glass comprises a mixed solution obtained by stirring metal nitrate, borohydride and an organic solvent;

b. the metal in the metal nitrate comprises at least one of nickel, zinc, cobalt, iron, titanium, tungsten, zirconium, aluminum, magnesium, yttrium and niobium;

c. the boron hydride compound comprises NaBH ₄ And KBH ₄ At least one of;

d. the organic solvent comprises at least one of absolute ethyl alcohol, diethyl ether, methanol, acetone, pentane and hexane;

e. the molar ratio of the metal nitrate, the borohydride and the organic solvent is (0.08-0.25): (0.5-1): (4-10).

8. The method for producing a positive electrode material according to claim 4, wherein at least one of the following characteristics a to d is satisfied:

a. the wet coating comprises the following steps: slowly dripping the solution containing the prepared metallic glass into the ternary material for stirring;

b. the dropping speed is 0.5L/min-3L/min;

c. the wet coating is carried out in a single cone;

d. and drying for 1-4 h after the wet coating is finished.

9. The method for producing a positive electrode material according to any one of claims 4 to 8, wherein the mass ratio of the ternary matrix material to the anionic covalent organic framework material is (0.9 to 0.99): (0.1-0.01);

and/or the chemical general formula of the ternary matrix material is Li _a Ni _x Co _y M _z O ₂ Wherein a is more than or equal to 0.95 and less than or equal to 1.1, x is more than or equal to 0.7 and less than or equal to 1, y + z is more than 0 and less than or equal to 0.3, and x + y + z=1, M comprises at least one of Mn and Al.

10. A lithium ion battery, wherein the lithium ion battery comprises the positive electrode material according to any one of claims 1 to 3, or the positive electrode material prepared by the preparation method according to any one of claims 4 to 9.