Preparation method of carbon-coated lithium nickel manganese oxide material and lithium battery containing carbon-coated lithium nickel manganese oxide material

Abstract

The invention relates to a preparation method of a carbon-coated lithium nickel manganese oxide material, and the preparation method comprises the following steps: 1, providing a precursor solution containing a lithium salt, a nickel salt, a manganese salt, a magnesium salt and a solvent, and carrying out spray pyrolysis treatment on the precursor solution to obtain a precursor containing magnesium; 2, performing heat treatment on the precursor to obtain a lithium nickel manganese oxide single crystal material; and 3, carrying out surface treatment on the lithium nickel manganese oxide single crystal material by using a carbon source to obtain the carbon-coated lithium nickel manganese oxide material.

Description

Technical Field

[0001] The present application relates to the technical field of lithium battery materials, and in particular to a method for preparing a carbon-coated lithium nickel manganese oxide material and a lithium battery comprising the same. Background Art

[0002] Under the background of dual carbon, electric vehicles are booming. Lithium-ion batteries have become the only choice for electric vehicle power batteries due to their high energy density and long cycle life; however, the energy density of lithium-ion batteries still needs to be further improved and their cost reduced to meet the industrial needs of electric vehicles. At present, the specific capacity of lithium-ion battery negative electrode materials is much higher than that of positive electrode materials. Therefore, positive electrode materials have become the main limiting factor for improving the energy density of lithium-ion batteries. 0.5 Mn 1.5 O 4 (LNMO) has a voltage platform of 4.7V and a theoretical specific capacity of 146.7mAh / g, so the corresponding energy density is as high as 650Wh / kg, which is higher than the current commercial LiFePO 4 It is 20% to 30% higher. In addition, LNMO materials also have the advantages of high power density, high thermal stability, and low cost, and have great application prospects. However, LNMO materials will have serious interfacial side reactions with electrolytes under high voltages, causing transition metals to dissolve, leading to material structure collapse, and causing a sharp deterioration in battery cycle stability and safety performance. In addition, the side reactions of LNMO materials and electrolytes are more intense at high temperatures, which seriously restricts their commercial applications. Summary of the invention

[0003] In view of the problems existing in the prior art, the present application provides a carbon-coated lithium nickel manganese oxide material and a preparation method thereof, wherein the preparation method comprises the following steps:

[0004] Step 1: providing a precursor solution comprising a lithium salt, a nickel salt, a manganese salt, a magnesium salt and a solvent, and subjecting the precursor solution to a spray pyrolysis treatment to obtain a precursor comprising magnesium, wherein the solvent comprises ethylene glycol and glycerol;

[0005] Step 2: subjecting the precursor to heat treatment to obtain a lithium nickel manganese oxide material, wherein the lithium nickel manganese oxide material includes primary particles, and the heat treatment comprises: subjecting the precursor to heat treatment at 800 to 1000° C. for 12 to 18 hours;

[0006] Step 3: Use a carbon source to perform surface treatment on the lithium nickel manganese oxide material to obtain the carbon-coated lithium nickel manganese oxide material.

[0007] In one aspect of the present application, the carbon source is selected from lauric acid or glucose, and the concentration of the lauric acid solution is selected from 0.01 mol / L to 0.2 mol / L.

[0008] In one aspect of the present application, the molar ratio of the metal elements in the lithium salt, the nickel salt, the manganese salt and the magnesium salt is selected from (1-1.1): (0.4-0.6): (1.3-1.5): (0.05-0.2).

[0009] In one aspect of the present application, the volume ratio of ethylene glycol to glycerol is selected from 3:1 to 5:1.

[0010] In one aspect of the present application, step 1 satisfies at least one of the following conditions (i)-(iii):

[0011] (i) using oxygen as a carrier gas in the spray pyrolysis process;

[0012] (ii) in the spray pyrolysis treatment, the pyrolysis temperature is selected from 700° C. to 900° C.;

[0013] (iii) In the precursor solution, the concentration of total metal is selected from 0.8 mol / L to 1.2 mol / L.

[0014] In one aspect of the present application, the heat treatment comprises: treating the precursor at 800-1000° C. for 12-18 hours, and then treating it at 600-700° C. for 3-8 hours.

[0015] In one aspect of the present application, the surface treatment comprises: adding the lithium nickel manganese oxide material to a lauric acid solution, stirring for 1 to 10 hours, filtering and drying, and then treating at 500° C. to 700° C. for 1 to 3 hours.

[0016] The present application provides a carbon-coated lithium nickel manganese oxide material, wherein the lithium nickel manganese oxide material is prepared by the aforementioned method, and the carbon-coated lithium nickel manganese oxide material comprises a lithium nickel manganese oxide material and a carbon coating layer.

[0017] In one aspect of the present application, the bulk phase of the lithium nickel manganese oxide material is doped with magnesium and has LiNi a Mn b Mg c O 4 The chemical formula of wherein 0.4≤a≤0.6, 1.3≤b≤1.5, and 0.05≤c≤0.2. The lithium nickel manganese oxide material has a spinel structure, and the metal M is located at the site where the transition metal is located in the spinel structure.

[0018] In one aspect of the present application, the carbon-coated lithium nickel manganese oxide material has a particle size of 0.5 μm to 3 μm.

[0019] In one aspect of the present application, the carbon coating layer has a thickness of 3 nm to 10 nm.

[0020] In one aspect of the present application, the tap density of the carbon-coated lithium nickel manganese oxide material is selected from 1.4 g / cm 3 ~2.0g / cm 3 .

[0021] In one aspect of the present application, the specific surface area of ​​the carbon-coated lithium nickel manganese oxide material is selected from 0.3 m 2 / g~1m 2 / g.

[0022] In one aspect of the present application, the carbon-coated lithium nickel manganese oxide material is a material with a carbon material coated on the surface and metallic magnesium doped in the bulk phase.

[0023] In one aspect of the present application, preferably, the carbon-coated lithium nickel manganese oxide material is a lithium nickel manganese oxide material with a surface coated with a carbon material and a bulk doped with magnesium.

[0024] In the present application, the bulk magnesium-doped lithium nickel manganese oxide material has LiNi a Mn b Mg c O 4 A chemical formula wherein 0.4≤a≤0.6, 1.3≤b≤1.5, and 0.05≤c≤0.2.

[0025] In the present application, the surface-coated carbon material and the magnesium-doped carbon-coated lithium nickel manganese oxide material has LiNi 0.5 Mn 1.4 Mg 0.1 O 4 、LiNi 0.5 Mn 1.3 Mg 0.2 O 4 、LiNi 0.5 Mn 1.45 Mg 0.05 O 4 The chemical formula of, but not limited to.

[0026] In the present application, the carbon coating layer coated on the surface has a thickness of 2 nm to 10 nm. Preferably, the carbon coating layer coated on the surface has a thickness of 2 nm to 5 nm.

[0027] In the present application, the magnesium element doped in the bulk phase is dispersed at the atomic level in the lithium nickel manganese oxide material.

[0028] In the present application, the carbon-coated lithium nickel manganese oxide material is a micron-sized material.

[0029] In one aspect of the present application, the lithium salt, the nickel salt and the manganese salt are selected from lithium nitrate, nickel nitrate and manganese nitrate.

[0030] In one aspect of the present application, the molar ratio of the lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate is selected from (1-1.1): (0.4-0.6): (1.3-1.5): (0.05-0.2).

[0031] In one aspect of the present application, preferably, the volume ratio of ethylene glycol to glycerol is 3.5:1 to 4.5:1, more preferably 4:1.

[0032] In one aspect of the present application, preferably, in the precursor solution, the concentration of total metal is selected from 1 mol / L.

[0033] In one aspect of the present application, the lauric acid solution is an ethanol solution of lauric acid.

[0034] In one aspect of the present application, preferably, the concentration of the lauric acid solution is selected from 0.08 mol / L to 0.12 mol / L.

[0035] In one aspect of the present application, more preferably, the concentration of the lauric acid solution is 0.1 mol / L.

[0036] In one aspect of the present application, preferably, the surface treatment comprises: adding the lithium nickel manganese oxide material to a lauric acid solution, stirring for 4 to 6 hours, filtering and drying, and then treating at 500° C. to 700° C. for 1 to 3 hours.

[0037] In one aspect of the present application, the preparation method comprises the following steps:

[0038] Step 1: lithium nitrate, nickel nitrate, manganese nitrate, magnesium nitrate and a solvent containing ethylene glycol and glycerol are configured into a precursor solution, and a precursor is obtained by spray pyrolysis treatment; wherein the volume ratio of the ethylene glycol and the glycerol is selected from 3:1 to 5:1, preferably 4:1; the molar ratio of the lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate is selected from (1-1.1): (0.4-0.6): (1.3-1.5): (0.05-0.2); in the spray pyrolysis treatment, oxygen is used as a carrier gas, and the pyrolysis temperature is selected from 700°C to 900°C.

[0039] Step 2: Treat the precursor at 800° C. to 1000° C. for 12 to 18 hours, and then treat it at 600° C. to 700° C. for 3 to 8 hours to obtain a lithium nickel manganese oxide material.

[0040] Step 3: adding the lithium nickel manganese oxide material to a 0.1 mol / L lauric acid solution, stirring for 2 to 7 hours, filtering and drying, and treating at 500° C. to 700° C. for 1 to 3 hours to obtain the carbon-coated lithium nickel manganese oxide material.

[0041] In one aspect of the present application, in the positive electrode involved in the present application, the positive electrode active material further includes a binder and / or a conductive agent.

[0042] The present application also provides a lithium battery, which includes a positive electrode and a negative electrode, wherein the positive electrode includes a positive electrode collector and a positive electrode active material, and the positive electrode active material includes the carbon-coated lithium nickel manganese oxide material prepared by the aforementioned preparation method or the aforementioned carbon-coated lithium nickel manganese oxide material.

[0043] Beneficial effects:

[0044] (1) The carbon-coated lithium nickel manganese oxide material of the present application adopts a dual modification method of bulk Mg element and carbon coating to reduce the side reaction with the electrolyte at high temperature, can maintain the morphology during the cycle, and is not easy to break and collapse, thereby improving the cycle stability of the material; the specific surface area is small, and when used as a positive electrode active material, it can further effectively reduce the contact area with the electrolyte, thereby reducing the side reaction with the electrolyte; and it also has a higher tap density.

[0045] (2) The method provided in the present application uses spray pyrolysis in the precursor synthesis stage to achieve the incorporation of magnesium doping elements into the lithium nickel manganese oxide material in the form of bulk doping, which can achieve uniform dispersion of the doping elements at the atomic level in the precursor. This method is simple in process, low in cost, and easy to implement industrial production. In particular, the spray pyrolysis method provided in the present application uses nitrate as a raw material, and uses ethylene glycol and glycerol as solvents. In the present application, since the precursor obtained by using an aqueous solution as a solvent for spray pyrolysis is relatively loose, it is difficult to obtain a material with primary particles. The method of the present application can be used to prepare a material with primary particles, and after treatment, an ultra-thin and dense carbon protective layer is covered on the surface of the material, thereby obtaining a positive electrode material with both high tap density and good morphology retention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The charge and discharge curves of Example 1 at 1C current density and 55°C are shown. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The relevant embodiments described herein are illustrative and are used to provide a basic understanding of the present application. The embodiments of the present application should not be interpreted as limiting the present application.

[0048] For simplicity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0049] the term:

[0050] In this article, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0051] In the description herein, unless otherwise specified, “above” and “below” include the number.

[0052] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0053] The term "about" is used to describe and illustrate small changes. When used in conjunction with an event or situation, the term may refer to an example in which the event or situation occurs precisely and an example in which the event or situation occurs very approximately. For example, when used in conjunction with a numerical value, the term may refer to a range of variation of less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. In addition, amounts, ratios, and other numerical values ​​are sometimes presented in this article in a range format. It should be understood that such a range format is for convenience and simplicity, and should be flexibly understood to include not only numerical values ​​explicitly designated as range limits, but also all individual 10 numerical values ​​or subranges encompassed within the range, as if each numerical value and subrange were explicitly designated.

[0054] A list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0055] The term "spray pyrolysis" is a type of aerosol method, which is characterized by the spraying of solutions, suspensions or dispersions into a reaction space (reactor) heated in various ways, and the formation and deposition of solid particles. Compared to spray drying with hot gases at temperatures <300°C, spray pyrolysis, as a high-temperature method, occurs in addition to evaporation of the solvent, thermal decomposition of the starting materials used (e.g. salts) and the formation of new substances (e.g. oxides, mixed oxides).

[0056] In this article, "primary particles" refer to crystals within a scale of several μm that do not contain grain boundaries and have basically the same crystal orientation throughout their interior. They are also called single crystal particles. In this article, "single crystal material" refers to materials with primary particles.

[0057] The present application is further described below in conjunction with specific implementations. It should be understood that these specific implementations are only used to illustrate the present application and are not used to limit the scope of the present application.

[0058] positive electrode:

[0059] In some embodiments of the present application, the positive electrode includes a positive electrode current collector and a positive electrode active material disposed on the positive electrode current collector.

[0060] In some embodiments of the present application, the positive electrode active material includes a carbon-coated lithium nickel manganese oxide material prepared by the preparation method of the present application.

[0061] In some embodiments of the present application, the carbon-coated lithium nickel manganese oxide material is a lithium nickel manganese oxide material with a surface coated with a carbon material and a bulk doped with magnesium, and the carbon-coated lithium nickel manganese oxide material includes primary particles.

[0062] In some embodiments of the present application, the carbon-coated lithium nickel manganese oxide material has LiNi a Mn b Mg c O 4A chemical formula wherein 0.4≤a≤0.6, 1.3≤b≤1.5, and 0.05≤c≤0.2.

[0063] In some embodiments of the present application, the surface-coated carbon material and bulk-doped magnesium lithium nickel manganese oxide material has LiNi 0.5 Mn 1.4 Mg 0.1 O 4 、LiNi 0.5 Mn 1.3 Mg 0.2 O 4 、LiNi 0.5 Mn 1.45 Mg 0.05 O 4 The chemical formula of, but not limited to.

[0064] In some embodiments of the present application, the lithium nickel manganese oxide material is prepared by the following preparation method:

[0065] Step 1: providing a precursor solution comprising a lithium salt, a nickel salt, a manganese salt, a magnesium salt and a solvent, and subjecting the precursor solution to a spray pyrolysis treatment to obtain a magnesium precursor;

[0066] Step 2: heat-treating the precursor to obtain a lithium nickel manganese oxide material, wherein the lithium nickel manganese oxide material includes primary particles;

[0067] Step 3: Use a carbon source to perform surface treatment on the lithium nickel manganese oxide material to obtain the carbon-coated lithium nickel manganese oxide material.

[0068] In some embodiments of the present application, the positive electrode active material further includes a binder, and optionally also includes a conductive agent. The binder improves the bonding between the positive electrode active material particles and also improves the bonding between the positive electrode active material and the current collector.

[0069] In some embodiments of the present application, the positive electrode current collector may be aluminum, but is not limited thereto.

[0070] negative electrode:

[0071] In some embodiments of the present application, the negative electrode includes a negative electrode current collector and a negative electrode active material disposed on the negative electrode current collector.

[0072] In some embodiments of the present application, the negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0073] In some embodiments of the present application, the negative electrode active material includes natural graphite; in addition, it may also include artificial graphite, MCMB, hard carbon, soft carbon, silicon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel-structured lithiated TiO 2 -Li 4 Ti 5 O 12 , Li-Al alloy. Non-limiting examples of carbon materials include crystalline carbon, amorphous carbon and mixtures thereof. Crystalline carbon can be amorphous or flake-shaped, platelet-shaped, spherical or fibrous natural graphite or artificial graphite. Amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, etc.

[0074] In some embodiments of the present application, the negative electrode active material may include a binder and optionally a conductive agent. The binder improves the bonding between the negative electrode active material particles and the bonding between the negative electrode active material and the current collector.

[0075] Diaphragm:

[0076] In some embodiments of the present application, the lithium-ion battery and electrochemical device of the present application are provided with a separator between the positive electrode and the negative electrode to prevent short circuit; the material and shape of the separator involved in the present application are not particularly limited, and it can be any technology disclosed in the prior art.

[0077] Electrolyte:

[0078] The lithium battery and electrochemical device involved in the present application also include an electrolyte, and the electrolyte includes a lithium salt and a solvent; the lithium salt and solvent involved in the present application are not particularly limited, and they can be any technology disclosed in the prior art.

[0079] In some embodiments of the present application, the electrolyte may optionally include additives.

[0080] Lithium battery:

[0081] In some embodiments of the present application, the lithium battery involved in the present application includes the above-mentioned positive electrode, negative electrode, separator, electrolyte, etc., but is not limited thereto.

[0082] In some embodiments of the present application, the present application further provides a battery module. The battery module includes the above-mentioned lithium-ion battery. The battery module of the present application uses the above-mentioned lithium-ion battery, and therefore has at least the same advantages as the lithium-ion battery. The number of lithium-ion batteries contained in the battery module of the present application can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0083] In some embodiments of the present application, the present application further provides a battery pack, which includes the above-mentioned battery module. The number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0084] Electrochemical device:

[0085] The present application also provides an electrochemical device, which includes at least one of the above-mentioned lithium battery, battery module or battery pack.

[0086] In some embodiments of the present application, the device includes, but is not limited to: electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, power storage systems, etc. In order to meet the device's requirements for high power and high energy density of lithium-ion batteries, a battery pack or battery module may be used.

[0087] In some other embodiments of the present application, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a lithium battery may be used as a power source.

[0088] The present application is further described below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application.

[0089] Embodiment 1:

[0090] Embodiment 1 comprises the following steps:

[0091] (1) Preparation of Mg-doped LiNi 0.5 Mn 1.4 O 4 Single crystal material:

[0092] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0093] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0094] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg0.1 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid ethanol solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 1. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0095] (2) Preparation of positive electrode sheet:

[0096] The positive electrode material, conductive carbon black and binder polyvinylidene chloride are mixed in a mass ratio of 97.5:1.5:1.0, and the mixture is dispersed in NMP to obtain a positive electrode slurry, and then the positive electrode slurry is evenly coated on the surface of the aluminum foil, and a positive electrode sheet is obtained after drying, calendering and vacuum drying.

[0097] (3) Preparation of negative electrode sheet:

[0098] Graphite, conductive carbon black, binder (styrene-butadiene rubber, polyacrylic acid) and sodium carboxymethyl cellulose are mixed in a mass ratio of 96.0:1.0:2.4:0.6, and the mixture is dispersed in deionized water to obtain a negative electrode slurry, and the negative electrode slurry is coated on the surface of a copper foil, and a negative electrode sheet is obtained after drying, calendering and vacuum drying.

[0099] (4) Assembling button batteries:

[0100] The above-mentioned positive electrode sheet and negative electrode sheet were used, and Celgard 2400 was used as a separator. The electrolyte was a 1M LiPF6 EC / DMC (volume ratio 7:3) solution to assemble a button battery CR2025.

[0101] Embodiment 2:

[0102] The steps of Example 2 are the same as those of Example 1, except that in Example 2, Mg-doped LiNi 0.5 Mn 1.3 O 4 Steps for single crystal materials:

[0103] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.3:0.2, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0104] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.3 Mg 0.2 O 4 Positive electrode material.

[0105] Weigh 3.5g LiNi 0.5 Mn 1.3 Mg 0.2 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid ethanol solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 2. 0.5 Mn 1.3 Mg 0.2 O 4 Positive electrode material.

[0106] Embodiment 3:

[0107] The steps of Example 3 are the same as those of Example 1, except that in Example 3, Mg-doped LiNi 0.5 Mn 1.45 O 4 Steps for single crystal materials:

[0108] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.45:0.05, and added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and a precursor solution with a total metal concentration of 1 mol / L was prepared; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0109] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.45 Mg 0.05 O 4 Positive electrode material.

[0110] Weigh 3.5g LiNi 0.5 Mn 1.45 Mg 0.05 O 4The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid ethanol solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 3. 0.5 Mn 1.45 Mg 0.05 O 4 Positive electrode material.

[0111] Embodiment 4:

[0112] The steps of Example 4 are the same as those of Example 1, except that in Example 4, Mg-doped LiNi 0.5 Mn 1.4 O 4 Steps for single crystal materials:

[0113] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0114] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0115] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid ethanol solution, stirred for 1 hour, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 4. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0116] Embodiment 5:

[0117] The steps of Example 5 are the same as those of Example 1, except that in Example 5, Mg-doped LiNi 0.5 Mn 1.4 O 4Steps for single crystal materials:

[0118] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0119] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0120] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid ethanol solution, stirred for 10 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 5. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0121] Embodiment 6:

[0122] The steps of Example 6 are the same as those of Example 1, except that in Example 6, Mg-doped LiNi 0.5 Mn 1.4 O 4 Steps for single crystal materials:

[0123] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0124] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0125] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.01 mol / L lauric acid ethanol solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 6. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0126] Embodiment 7:

[0127] The steps of Example 7 are the same as those of Example 1, except that in Example 7, Mg-doped LiNi 0.5 Mn 1.4 O 4 Steps for single crystal materials:

[0128] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0129] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0130] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.2 mol / L lauric acid ethanol solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 7. 0.5 Mn 1.4 Mg 0.1 O 4Positive electrode material.

[0131] Embodiment 8:

[0132] The steps of Example 8 are the same as those of Example 1, except that in Example 8, Mg-doped LiNi 0.5 Mn 1.4 O 4 Steps for single crystal materials:

[0133] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, and added into a mixture of ethylene glycol / glycerol (volume ratio of 3:1), stirred and dissolved, and a precursor solution with a total metal concentration of 1 mol / L was prepared; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0134] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0135] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid ethanol solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600°C for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 8. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0136] Embodiment 9:

[0137] The steps of Example 9 are the same as those of Example 1, except that in Example 9, Mg-doped LiNi 0.5 Mn 1.4 O 4 Steps for single crystal materials:

[0138] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, and added into a mixture of ethylene glycol / glycerol (volume ratio of 5:1), stirred and dissolved, and a precursor solution with a total metal concentration of 1 mol / L was prepared; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0139] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0140] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid ethanol solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 9. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0141] Embodiment 10:

[0142] The steps of Example 10 are the same as those of Example 1, except that the carbon source for carbon coating in Example 10 is selected differently:

[0143] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0144] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0145] Weigh 3.5gLiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L glucose aqueous solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the surface carbon-coated micron-sized single crystal LiNi of Example 10. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0146] Comparative Example 1:

[0147] The steps of Comparative Example 1 are the same as those of Example 1, except that the positive electrode material prepared in Comparative Example 1 is LiNi 0.5 Mn 1.5 O 4 Single crystal material, the steps are as follows:

[0148] Lithium nitrate, nickel nitrate and manganese nitrate were weighed according to a molar ratio of Li:Ni:Mn=1.05:0.5:1.5, and added to a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and a precursor solution with a total metal concentration of 1 mol / L was prepared; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0149] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain the single crystal LiNi 0.5 Mn 1.5 O 4 Positive electrode material.

[0150] Comparative Example 2:

[0151] The steps of Comparative Example 2 are the same as those of Example 1, except that in Comparative Example 2, Mg-doped LiNi 0.5 Mn 1.4 O 4 Steps for single crystal materials:

[0152] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into a mixture of ethylene glycol / glycerol (volume ratio of 4:1), stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0153] The precursor powder was treated at 900°C in a muffle furnace for 15 hours, then cooled to 650°C and annealed for 5 hours to obtain Mg-doped micron-sized single-crystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0154] Comparative Example 3:

[0155] The steps of Comparative Example 3 are the same as those of Example 1, except that in Comparative Example 3, Mg-doped LiNi 0.5 Mn 1.4 Steps for O4 single crystal material:

[0156] Lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate were weighed according to the molar ratio of Li:Ni:Mn:Mg=1.05:0.5:1.4:0.1, added into water, stirred and dissolved, and prepared into a precursor solution with a total metal concentration of 1 mol / L; the precursor solution was subjected to gasification spray pyrolysis, wherein the carrier gas was oxygen and the pyrolysis temperature was 800° C., to obtain a precursor powder;

[0157] The precursor powder was treated at 700 °C in a muffle furnace for 15 hours to obtain Mg-doped polycrystalline LiNi 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0158] Weigh 3.5g LiNi 0.5 Mn 1.4 Mg 0.1 O 4 The positive electrode material was added to 100 ml of 0.1 mol / L lauric acid aqueous solution, stirred for 5 hours, filtered and dried, and then treated in a muffle furnace at 600° C. for 2 hours to obtain the carbon-coated polycrystalline LiNi of Comparative Example 3. 0.5 Mn 1.4 Mg 0.1 O 4 Positive electrode material.

[0159]

Test method

[0160] Discharge specific capacity and capacity retention rate:

[0161] (1) 1C discharge specific capacity and 1C capacity retention rate test at 25°C:

[0162] l) Place the lithium-ion battery in a 25°C constant temperature box for 12 hours;

[0163] 2) CC-CV charging to 4.95V at 1 / 3C, with a cut-off current of 0.05C;

[0164] 3) Let stand for 10 minutes, then discharge 1 / 3C to 3.5V;

[0165] 4) Repeat steps 2)-3) 3 times;

[0166] 5) Then charge to 4.95V with 1C CC-CV, cut-off current of 0.05C, and let stand for 10min;

[0167] 6) Then discharge at 1C to 3.5V, let stand for 10min, and take the first 1C discharge capacity as 1C 初始放电比容量 ;

[0168] 7) Repeat steps 5-6 499 times, and take the 499th 1C discharge capacity as 1C 500圈放电比容量 ;

[0169] 8) Calculate 1C at 25℃ 500圈放电比容量 With 1C 初始放电比容量 The ratio is the 1C capacity retention rate.

[0170] (2) 1C discharge specific capacity and 1C capacity retention rate test at 55°C:

[0171] 1) Place the lithium-ion battery in a 55°C constant temperature box for 12 hours;

[0172] 2) 1 / 3C CC-CV charge to 4.95V, cut-off current is 0.05C;

[0173] 3) Let stand for 10 minutes, then discharge 1 / 3C to 3.5V;

[0174] 4) Repeat steps 2)-3) 3 times;

[0175] 5) Then charge to 4.95V with 1C CC-CV, cut-off current of 0.05C, and let stand for 10min;

[0176] 6) Then discharge at 1C to 3.5V, let stand for 10min, and take the first 1C discharge capacity as 1C 初始放电比容量 ;

[0177] 7) Repeat steps 5)-6) 199 times, and take the 199th 1C discharge capacity as 55℃1C 200圈放电比容量 ;

[0178] 8) Calculate 1C at 55℃ 200圈放电比容量 With 1C 初始放电比容量 The ratio is the 1C capacity retention rate.

[0179] The performance tests and electrochemical tests of Examples 1-10 and Comparative Examples 1-5 were performed, and the results are shown in Table 1. The charge and discharge curves of Example 1 are shown in Table 1. Figure 1 As shown:

[0180] [Table 1]

[0181]

[0182]

[0183] It can be seen from Table 1 that the cycle stability of the lithium nickel manganese oxide polycrystalline material of Comparative Example 1 is the worst; compared with Comparative Example 2, it can be seen that the cycle stability of the lithium nickel manganese oxide single crystal material doped with Mg element is better than that of the lithium nickel manganese oxide single crystal material not doped with Mg element.

[0184] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the present application, and that changes, substitutions and modifications may be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. A method for preparing a carbon-coated lithium nickel manganese oxide material, characterized in that: The preparation method comprises the following steps: Step 1: providing a precursor solution comprising a lithium salt, a nickel salt, a manganese salt, a magnesium salt and a solvent, and subjecting the precursor solution to a spray pyrolysis treatment to obtain a precursor comprising the doped metal magnesium, wherein the solvent comprises ethylene glycol and glycerol; Step 2: subjecting the precursor to heat treatment to obtain a lithium nickel manganese oxide material, wherein the lithium nickel manganese oxide material includes primary particles, and the heat treatment comprises: subjecting the precursor to heat treatment at 800° C. to 1000° C. for 12 to 18 hours; Step 3: Use a carbon source to perform surface treatment on the lithium nickel manganese oxide material to obtain the carbon-coated lithium nickel manganese oxide material.

2. The preparation method according to claim 1, characterized in that: The method satisfies at least one of the following conditions: (1) The carbon source includes lauric acid or glucose; (2) The volume ratio of ethylene glycol to glycerol is selected from 3:1 to 5:

1.

3. The preparation method according to claim 1, wherein The step 1 satisfies at least one of the following conditions: (1) The lithium salt, the nickel salt, the manganese salt and the magnesium salt are lithium nitrate, nickel nitrate, manganese nitrate and magnesium nitrate; (2) The molar ratio of the metal elements in the lithium salt, the nickel salt, the manganese salt and the magnesium salt is selected from (1-1.1): (0.4-0.6): (1.3-1.5): (0.05-0.2).

4. The preparation method according to claim 1, wherein The step 1 satisfies at least one of the following conditions: (1) In the spray pyrolysis process, oxygen is used as a carrier gas; (2) In the spray pyrolysis treatment, the pyrolysis temperature is selected from 700° C. to 900° C.; (3) In the precursor solution, the concentrations of the lithium salt, the nickel salt, the manganese salt and the magnesium salt are selected from 0.8 mol / L to 1.2 mol / L.

5. The method according to claim 1, wherein: The heat treatment comprises: treating the precursor at 800° C. to 1000° C. for 12 to 18 hours, and then treating it at 600° C. to 700° C. for 3 to 8 hours.

6. The method according to claim 1, wherein: The surface treatment includes at least one of the following conditions: (1) mixing the lithium nickel manganese oxide material with a solution containing a carbon source, filtering, and treating at 500° C. to 700° C. for 1 to 3 hours; (2) The concentration of the solution containing the carbon source is selected from 0.01 mol / L to 0.2 mol / L.

7. A carbon-coated lithium nickel manganese oxide material, characterized in that: The carbon-coated lithium nickel manganese oxide material comprises a lithium nickel manganese oxide material and a carbon coating layer coated on the surface of the lithium nickel manganese oxide material. The lithium nickel manganese oxide material has LiNi a Mn b M c O4, wherein 0.4≤a≤0.6, 1.3≤b≤1.5, 0.05≤c≤0.2, the carbon-coated lithium nickel manganese oxide material includes primary particles, and the metal M includes magnesium.

8. The carbon-coated lithium nickel manganese oxide material according to claim 7, characterized in that: The carbon-coated lithium nickel manganese oxide material satisfies at least one of the following conditions: (1) The particle size of the carbon-coated lithium nickel manganese oxide material is 0.5 μm to 3 μm; (2) The thickness of the carbon coating layer is 2 nm to 10 nm; (3) The tap density of the carbon-coated lithium nickel manganese oxide material is selected from 1.4 g / cm 3 ~2.0g / cm 3 ; (4) The specific surface area of ​​the carbon-coated lithium nickel manganese oxide material is selected from 0.3 m 2 / g~1m 2 / g.

9. A carbon-coated lithium nickel manganese oxide material, characterized in that: The carbon-coated lithium nickel manganese oxide material is prepared by the method described in claims 1 to 6.

10. A lithium battery, characterized in that: The lithium battery comprises a carbon-coated lithium nickel manganese oxide material prepared by the preparation method according to any one of claims 1 to 6 or a carbon-coated lithium nickel manganese oxide material according to claims 7 to 9.

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