CN109994726B - Positive electrode material precursor, preparation method thereof, positive electrode material and lithium ion battery - Google Patents

Positive electrode material precursor, preparation method thereof, positive electrode material and lithium ion battery Download PDF

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CN109994726B
CN109994726B CN201711481516.2A CN201711481516A CN109994726B CN 109994726 B CN109994726 B CN 109994726B CN 201711481516 A CN201711481516 A CN 201711481516A CN 109994726 B CN109994726 B CN 109994726B
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positive electrode
electrode material
precursor
hexagonal
salt
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CN109994726A (en
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陈建生
周云鹏
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Hubei Jiubang New Energy Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention provides a precursor of a positive electrode material, which has a general formula shown as a formula (I): nixCoyMnzAl1‑x‑y‑z(OH)2(I) (ii) a The positive electrode material precursor is spherical particles formed by hexagonal pieces of the positive electrode material precursor, and the hexagonal pieces of the positive electrode material precursor are compounded with the nano particles of the positive electrode material precursor. The precursor of the ternary or quaternary anode material is prepared by the invention, the hexagonal pieces form spherical particles, the precursor hexagonal pieces are also compounded with the nano particles of the precursor, the multilayer hexagonal sheets and the nano particles on the surfaces of the hexagonal sheets form spherical particles, the structure is complete and uniform, the nano particles on the surfaces of the hexagonal sheets can effectively improve the processing performance of the anode material, improve the structural stability of the anode material and improve the cycle performance of the anode material, and the nano particles on the surfaces of the hexagonal sheets also increase the specific surface area of the material, reduce the internal resistance in the material cycle process and improve the rate capability of the material.

Description

Positive electrode material precursor, preparation method thereof, positive electrode material and lithium ion battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a precursor of a positive electrode material, a preparation method of the precursor, the positive electrode material and a lithium ion battery.
Background
The lithium ion battery generally comprises a positive electrode, a negative electrode, a diaphragm, electrolyte and a shell, has the advantages of high working voltage, high specific energy, long cycle life, light weight, less self-discharge, no memory effect, high cost performance and the like, and becomes a main selection object of a rechargeable power supply in the fields of high-power electric vehicles, artificial satellites, aerospace and the like. In all components of the lithium ion battery, particularly after the invention of the super-concentrated electrolyte, the electrode material is always the main bottleneck for improving the energy density of the lithium ion battery, and the anode is one of the key materials of the lithium ion battery, determines the performance of the lithium ion battery, and therefore is also always a research hotspot of researchers. The positive electrode, i.e., the positive electrode sheet, of the lithium ion battery generally includes a positive active material, a conductive agent, a binder, a solvent, and a current collector, among which the most critical is the positive active material. Particularly, beginning in 2015, the new energy automobile industry is in full outbreak period, and compared with the traditional automobile, the endurance and the safety of the new energy automobile determined by the power battery are always the core of attention of new energy automobile manufacturers and consumers; the key point of improving the endurance mileage of the vehicle is to improve the energy density of the power battery, and more battery manufacturers begin to vigorously develop research and development work of the high-energy-density power battery.
In the current power lithium ion battery anode materials, a nickel cobalt lithium manganate ternary anode material (NCM) and a nickel cobalt lithium aluminate ternary anode material (NCA) have the advantages of high energy density, low cost, environmental friendliness and the like due to the synergistic effect of the three elements, and become anode active materials with great increment in the power lithium ion battery application field in the global market in recent years. Taking NCM as an example, when the voltage is in the range of 3.0-4.3V, the specific capacitance is only 130-150 mA/hg although the cycle life and the cycle life are longer. Through continuous research in the industry, in recent years, reports indicate that the service life of the battery is not influenced when the battery capacity of the material is increased, so that the ternary NCM cathode material has attracted great interest in the academic and industrial fields in improving the gram capacity. Such as cation/anion doping, coatings, design of concentration gradients, and the like. However, the actual capacity of the improved ternary NCM material is still lower than 200mA/hg, and the structural stability and cycle performance of the improved ternary NCM material are not ideal, especially the structural stability is reduced.
Therefore, how to solve the problems of the ternary cathode material in terms of structural stability, battery capacity, electrochemical cycle performance and the like has become one of the focuses of great concern of many manufacturers and first-line researchers in the industry.
Disclosure of Invention
In view of the above, the present invention provides a precursor of a positive electrode material and a method for preparing the same. The positive electrode material prepared by the positive electrode material precursor provided by the invention is used for lithium ion batteries, and has high structural stability, high battery capacity and good electrochemical cycle performance. Meanwhile, the preparation method provided by the invention is simple in process, mild in condition and suitable for large-scale production and application.
The invention provides a precursor of a positive electrode material, which has a general formula shown as a formula (I):
NixCoyMnzAl1-x-y-z(OH)2 (I)；
wherein x is more than 0 and less than 1, y is more than 0 and less than 1, x + y is less than 1, z is more than or equal to 0 and less than 1, and x + y + z is less than or equal to 1;
the positive electrode material precursor is spherical particles formed by hexagonal pieces of the positive electrode material precursor, and the hexagonal pieces of the positive electrode material precursor are compounded with the nano particles of the positive electrode material precursor.
Preferably, the hexagonal plates of the positive electrode material precursor include a multilayer body composed of a plurality of hexagonal plates, or a multilayer body composed of a plurality of hexagonal plates and a single-layer hexagonal plate;
the number of the layers is 2-50;
the particle size of the nano particles is 100-300 nm;
the mass ratio of the positive electrode material precursor hexagonal piece to the positive electrode material precursor nano particles is 10: (1-5).
Preferably, the composition is formed by stacking;
the thickness of the multilayer hexagonal sheet is 50-200 nm;
gaps are reserved among the layers of the multilayer hexagonal sheets;
the anode material precursor nano particles are compounded on the surfaces of the multilayer hexagonal plates and in the gaps of the layers.
The invention provides a preparation method of a precursor of a positive electrode material, which comprises the following steps:
1) mixing nickel salt, manganese salt and/or aluminum salt, cobalt salt and water to obtain a mixed solution;
2) adding the mixed solution, a complexing agent and alkali, and reacting to obtain a first mixed solution;
3) continuously adding the mixed solution, the complexing agent and the alkali into the first mixed solution obtained in the step, and reacting again to obtain a second mixed solution;
4) and aging the second mixed solution obtained in the step to obtain the precursor of the anode material.
Preferably, the step 1) is specifically:
mixing nickel salt, manganese salt, cobalt salt and water to obtain a primary mixed solution;
mixing aluminum salt and water to obtain an aluminum salt solution; the molar concentration of the aluminum salt solution is 0.1-2 mol/L;
and mixing the primary mixed solution and the aluminum salt solution to obtain a mixed solution.
Preferably, in the mixed liquid, the total molar concentration of the manganese salt and/or the aluminum salt, the nickel salt and the cobalt salt is 1-3.5 mol/L;
the alkali is selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide;
the complexing agent is selected from one or more of ammonia water, ammonium bicarbonate, ammonium carbonate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium nitrate and urea;
in the step 2), the ratio of the mole number of the complexing agent to the total mole number of the nickel salt, the manganese salt and/or the aluminum salt and the cobalt salt is (1-10): 1;
the pH value of the reaction is 7.5-12.0;
the reaction time is 4-36 h;
the reaction temperature is 40-70 ℃.
Preferably, in the step 3), the ratio of the mole number of the complexing agent to the total mole number of the nickel salt, the manganese salt and/or the aluminum salt and the cobalt salt is (5-20): 1;
the pH value of the secondary reaction is 9.5-13.0;
the pH value of the secondary reaction is 0.25-2 higher than that of the reaction;
the secondary reaction time is 36-50 h;
the temperature of the secondary reaction is 45-65 ℃;
the aging time is 20-40 h.
The invention provides a positive electrode material, which has a general formula shown as a formula (II):
Li1+wNixCoyMnzAl1-x-y-zO2 (II)，
wherein x is more than 0 and less than 1, y is more than 0 and less than 1, x + y is less than 1, z is more than or equal to 0 and less than 1, x + y + z is less than or equal to 1, and w is more than or equal to-0.5 and less than or equal to 0.5;
the anode material is spherical particles formed by anode material hexagonal plates, and the anode material nano particles are compounded on the anode material hexagonal plates.
Preferably, the positive electrode material is obtained by heat treatment of the positive electrode material precursor according to any one of the above technical schemes or the positive electrode material precursor prepared by the preparation method according to any one of the above technical schemes and lithium salt;
the temperature of the heat treatment is 725 ℃ to 1150 ℃.
The invention also provides a lithium ion battery which comprises the anode material in any one of the technical schemes.
The invention provides a precursor of a positive electrode material, which has a general formula shown as a formula (I): nixCoyMnzAl1-x-y-z(OH)2(I) (ii) a Wherein, 0<x<1，0＜y<1，0≤z<1, x + y + z is less than or equal to 1; the positive electrode material precursor is spherical particles formed by hexagonal pieces of the positive electrode material precursor, and the hexagonal pieces of the positive electrode material precursor are compounded with the nano particles of the positive electrode material precursor. Compared with the prior art, the invention aims at the problems of lower capacity, and unsatisfactory structural stability and cycle performance of the existing improved ternary material. The invention starts from the precursor of the anode material, creatively obtains the precursor of the ternary or quaternary anode material, hexagonal tablets form spherical particles, and the hexagonal tablets of the precursor are also compounded with nano particles of the precursor, the secondary spherical particles formed by the multilayer hexagonal tablets and the nano particles on the surface of the multilayer hexagonal tablets have complete and uniform structure, the nano particles on the hexagonal tablet surface can effectively improve the processing performance of the anode material, improve the structural stability of the anode material and improve the cycle performance of the anode material, and meanwhile, the nano particles on the hexagonal tablet surface increase the specific surface area of the material, reduce the internal resistance of the material in the cycle process and improve the rate capability of the material. And the preparation method has simple process and mild conditions, and is suitable for large-scale production and application.
Compared with the prior anode material precursor with a similar structure and containing colloidal particle materials, the anode material precursor provided by the invention is made of the same material, and the nano particles can be embedded and filled between the sheets of the multilayer body, so that the material is uniform, the structure stability is better, and the cycle performance is improved. And the specific surface area of the material is increased by embedding and filling, the interface internal resistance in the circulation process is reduced, and the rate capability of the anode material is improved.
Experimental results show that the lithium ion battery cathode material prepared by the invention has excellent processability and good cycle performance and rate capability, the 0.1C discharge capacity is 194mAh/g, the 5C discharge capacity is 162mAh/g, and the capacity retention rate of 60 circles is 95%.
Drawings
Fig. 1 is an SEM scanning electron microscope image of a nickel-cobalt-manganese ternary material precursor prepared in example 1 of the present invention at a scale of 5 μm;
FIG. 2 is an SEM scanning electron microscope image of a Ni-Co-Mn ternary material precursor prepared in example 1 of the present invention at a size of 1 μm;
fig. 3 is an SEM scanning electron microscope image of the nickel-cobalt-manganese ternary positive electrode material prepared in example 1 of the present invention;
fig. 4 is an SEM scanning electron microscope image of the nickel-cobalt-manganese ternary positive electrode material prepared in example 1 of the present invention;
FIG. 5 is a schematic diagram of a ternary precursor prepared according to an embodiment of the present invention;
fig. 6 is an electrochemical performance diagram of the nickel-cobalt-manganese ternary positive electrode material prepared in example 1 of the present invention.
Detailed Description
In order to further understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a precursor of a positive electrode material, which has a general formula shown as a formula (I):
NixCoyMnzAl1-x-y-z(OH)2 (I)；
wherein x is more than 0 and less than 1, y is more than 0 and less than 1, x + y is less than 1, z is more than or equal to 0 and less than 1, and x + y + z is less than or equal to 1;
the positive electrode material precursor is spherical particles formed by hexagonal pieces of the positive electrode material precursor, and the hexagonal pieces of the positive electrode material precursor are compounded with the nano particles of the positive electrode material precursor.
The positive electrode material is not particularly limited in the present invention, and may be defined by a conventional positive electrode material well known to those skilled in the art, and those skilled in the art can select and adjust the material according to the application, product performance and quality requirements, and the positive electrode material precursor of the present invention preferably includes a precursor of a ternary positive electrode material and/or a quaternary positive electrode material, more preferably a precursor of a ternary positive electrode material or a quaternary positive electrode material, and more preferably a precursor of a ternary positive electrode material of nickel cobalt lithium manganate (NCM), a ternary positive electrode material of nickel cobalt lithium aluminate (NCA) or a quaternary positive electrode material of Nickel Cobalt Manganese Aluminate (NCMA).
The definition of the precursor is not particularly limited in the present invention, and may be defined by the definition of the conventional cathode material precursor known to those skilled in the art, and those skilled in the art can select and adjust the precursor according to the application, product performance and quality requirements, and the cathode material precursor of the present invention is preferably a hydroxide precursor of the cathode material. It has a general formula as shown in formula (I):
NixCoyMnzAl1-x-y-z(OH)2(I) (ii) a Wherein, 0<x<1，0＜y<1，x+y<1，0≤z<1，x+y+z≤1。
In the invention, when z is 0, the formula (I) is a general formula of the nickel cobalt lithium aluminate ternary positive electrode material hydroxide precursor; when x + y + z is 1, the formula (I) is a general formula of a nickel cobalt lithium manganate ternary positive electrode material hydroxide precursor; when z is not equal to 0 and x + y + z is not equal to 1, the formula (I) is a general formula of the nickel-cobalt-manganese-lithium aluminate quaternary positive electrode material hydroxide precursor. In the present invention, when x + y + z is 1, z ≠ 0, i.e., x + y < 1.
The precursor of the positive electrode material is spherical particles consisting of hexagonal pieces of the precursor of the positive electrode material, and the hexagonal pieces of the precursor of the positive electrode material are compounded with the nano particles of the precursor of the positive electrode material. The structure of the positive electrode material precursor provided by the invention is made of the positive electrode material precursor.
The invention has no special limitation on the composition mode of the precursor hexagonal tablet forming spherical particles (or spheroidal particles), and the precursor hexagonal tablet forming spherical particles (or spheroidal particles) can be prepared by a conventional composition mode well known to a person skilled in the art, and the person skilled in the art can select and adjust the composition according to the application situation, the product performance and the quality requirement, and the composition is preferably formed by stacking; the hexagonal plates of the precursor can be self-assembled into a multilayer body by a plurality of sheets, and the multilayer body is stacked to form spherical particles, wherein a single layer of hexagonal plates is also mixed. That is, the hexagonal plate of the positive electrode material precursor of the present invention preferably includes a multilayer body composed of a plurality of hexagonal plates, or a multilayer body composed of a plurality of hexagonal plates and a single hexagonal plate.
The number of layers of the multilayer is not particularly limited, and is determined by a conventional number of layers known to those skilled in the art, and the number of layers of the multilayer can be selected and adjusted by those skilled in the art according to application conditions, product performance and quality requirements, and is preferably 2-50 layers, more preferably 12-40 layers, and more preferably 22-30 layers.
The thickness of the multilayer hexagonal sheet, i.e. the thickness of the multilayer body, is not particularly limited, and can be selected and adjusted by the skilled in the art according to the application, product performance and quality requirements, and the thickness of the multilayer hexagonal sheet is preferably 50-200 nm, more preferably 75-175 nm, more preferably 100-150 nm, and particularly 80-150 nm.
The stacked multilayer bodies of the present invention have voids between them, and more particularly, the present invention has voids between the individual sheets in the structure of a single multilayer body, and the voids between the sheets of the multilayer hexagonal sheets of the present invention. The precursor nano-particles of the cathode material are compounded in the gaps among the stacked multilayer bodies, and are also compounded on the surfaces of the multilayer hexagonal plates and the plate gaps of the single multilayer bodies.
The present invention is not particularly limited in the form of the composite, and may be defined as a composite known to those skilled in the art, and the present invention is preferably deposited, grown, filled, clad, modified, layered or generated, more preferably deposited, grown or filled, and most preferably deposited or filled.
The ratio of the hexagonal plates to the nanoparticles is not particularly limited, and may be a conventional ratio well known to those skilled in the art, and those skilled in the art may select the ratio according to actual production conditions, product conditions and product performance, and the mass ratio of the hexagonal plates of the positive electrode material precursor to the nanoparticles of the positive electrode material precursor in the present invention is preferably 10: (1-5), more preferably 10: (1.5 to 4.5), more preferably 10: (2-4), more preferably 10: (2.5-3.5).
The particle size of the nanoparticles is not particularly limited, and can be selected and adjusted by the skilled in the art according to the application, product performance and quality requirements, and is preferably 100-300 nm, more preferably 120-280 nm, more preferably 150-250 nm, and more preferably 180-230 nm. The shape of the nanoparticles is not particularly limited in the present invention, and may be the shape of conventional nanoparticles well known to those skilled in the art, and those skilled in the art can select and adjust the shape according to the application, product performance and quality requirements, and the nanoparticles of the present invention are preferably irregular-shaped nanoparticles, and may be spherical, cubic or polygonal.
The particle size of the spherical particles is not particularly limited, and can be selected and adjusted according to the application condition, product performance and quality requirements by a person skilled in the art according to the particle size of a conventional positive electrode material precursor well known by the person skilled in the art, and the particle size of the spherical particles is preferably 5-15 μm, more preferably 7-13 μm, and more preferably 9-11 μm.
The steps of the invention provide a precursor of the cathode material, hexagonal sheets are stacked to form primary particles (multilayer body), gaps are arranged among layers of the multilayer body, nano particles are deposited on the surfaces of the layers of the multilayer body and in the gaps, and a plurality of multilayer bodies and single hexagonal sheets are stacked to form the precursor of the cathode material of the lithium ion battery. Compared with the prior anode material precursor with a similar structure and containing colloidal particle materials, the anode material precursor provided by the invention is made of the same material, and the nano particles can be embedded and filled between the sheets of the multilayer body, so that the material is uniform, the structure stability is better, and the cycle performance is improved. And the specific surface area of the material is increased by embedding and filling, the interface internal resistance in the circulation process is reduced, and the rate capability of the anode material is improved.
The invention provides a preparation method of a precursor of a positive electrode material, which comprises the following steps:
1) mixing nickel salt, manganese salt and/or aluminum salt, cobalt salt and water to obtain a mixed solution;
2) adding the mixed solution, a complexing agent and alkali, and reacting to obtain a first mixed solution;
3) continuously adding the mixed solution, the complexing agent and the alkali into the first mixed solution obtained in the step, and reacting again to obtain a second mixed solution;
4) and aging the second mixed solution obtained in the step to obtain the precursor of the anode material.
In the present invention, the selection and proportion of the materials in the preparation method, and the corresponding preferred principle thereof, if not specifically noted, are preferably consistent with the selection and proportion of the materials in the precursor of the positive electrode material, and the corresponding preferred principle thereof, and thus are not described in detail herein.
Firstly, mixing nickel salt, manganese salt and/or aluminum salt, cobalt salt and water to obtain a mixed solution.
The adding proportion of the water is not particularly limited, the proportion of the solvent is known by the person skilled in the art, the person skilled in the art can select and adjust the proportion according to the production condition, the product performance and the quality requirement, and in the mixed liquid, the total molar concentration of the manganese salt and/or the aluminum salt, the nickel salt and the cobalt salt is preferably 1-3.5 mol/L, more preferably 1.5-3 mol/L, and more preferably 2-2.5 mol/L.
The specific selection of the nickel salt, the manganese salt and/or the aluminum salt and the cobalt salt is not particularly limited in the present invention, and conventional salts well known to those skilled in the art may be used, and those skilled in the art may select and adjust the salts according to the production situation, the product performance and the quality requirement, and the nickel salt is preferably one or more of nickel sulfate, nickel nitrate, nickel oxalate and nickel chloride; the cobalt salt is preferably one or more of cobalt sulfate, cobalt nitrate, cobalt oxalate and cobalt chloride; the manganese salt is preferably one or more of manganese sulfate, manganese nitrate, manganese oxalate and manganese chloride; the aluminium salt is preferably one or more of aluminium sulphate, aluminium nitrate, aluminium oxalate and aluminium chloride.
The ratio of the nickel salt, the manganese salt and/or the aluminum salt and the cobalt salt is not particularly limited in the present invention, and may be the ratio of the conventional ternary or quaternary positive electrode material well known to those skilled in the art, and those skilled in the art can select and adjust the ratio according to the production situation, the product performance and the quality requirement, and the molar ratio of the nickel salt, the manganese salt and/or the aluminum salt and the cobalt salt in the present invention is preferably x: (1-x-y): y, wherein the molar ratio of manganese salt to aluminum salt is preferably z: (1-x-y-z).
The mixing method and procedure of the present invention are not particularly limited, and may be selected and adjusted by those skilled in the art according to the production situation, product performance and quality requirements, and the mixing method and procedure of the present invention is preferably stirring mixing. In order to improve the mixing effect and ensure the performance of the final product, the mixing method can preferably adopt the mixing step when the precursor is a ternary cathode material precursor or a quaternary cathode material precursor; when the precursor is a quaternary positive electrode material precursor, the following mixing steps are more preferably adopted:
mixing nickel salt, manganese salt, cobalt salt and water to obtain a primary mixed solution;
mixing aluminum salt and water to obtain an aluminum salt solution;
and mixing the primary mixed solution and the aluminum salt solution to obtain a mixed solution.
The concentration of the aluminum salt solution is not particularly limited in the present invention, and may be a conventional concentration well known to those skilled in the art, and those skilled in the art can select and adjust the concentration according to the production situation, product performance and quality requirements, and the molar concentration of the aluminum salt solution in the present invention is preferably 0.1 to 2mol/L, more preferably 0.4 to 1.6mol/L, and more preferably 0.8 to 1.2 mol/L.
The mixed solution, the complexing agent and the alkali are added to react to obtain a first mixed solution, namely the mixed solution, the complexing agent and the alkali are added to a reaction container to react to obtain the first mixed solution. The mixed solution is the mixed solution obtained in the above steps.
The choice of the complexing agent is not particularly limited by the present invention, and may be a conventional complexing agent for such reactions well known to those skilled in the art, and may be selected and adjusted by those skilled in the art according to the production situation, product performance and quality requirements, and the complexing agent of the present invention is preferably one or more selected from the group consisting of ammonia, ammonium bicarbonate, ammonium carbonate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium nitrate and urea, more preferably ammonia, ammonium bicarbonate, ammonium carbonate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium nitrate or urea, and most preferably ammonia.
The amount of the complexing agent used in the present invention is not particularly limited, and may be the amount of the conventional complexing agent used in such reactions well known to those skilled in the art, and those skilled in the art can select and adjust the amount according to the production situation, product performance and quality requirements, and in the step 2) of the present invention, the ratio of the number of moles of the complexing agent to the total number of moles of the nickel salt, manganese salt and/or aluminum salt, cobalt salt is preferably (1-10): 1, more preferably (3-8): 1, more preferably (5-6): 1.
in order to improve the appearance of a final product, complete and refine the preparation process, the complexing agent is preferably a complexing agent solution, and the concentration of the complexing agent solution is preferably 0.1-3 mol/L, more preferably 0.5-2.5 mol/L, and more preferably 1-2 mol/L.
The selection of the base is not particularly limited in the present invention, and may be a base known to those skilled in the art, and those skilled in the art can select and adjust the base according to the production situation, the product performance and the quality requirement, and the base in the present invention is preferably selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide, more preferably lithium hydroxide, sodium hydroxide or potassium hydroxide, and most preferably sodium hydroxide.
The amount of the alkali used is not particularly limited, and can be selected and adjusted by a person skilled in the art according to the production condition, the product performance and the quality requirement. In the step 2), the pH of the first mixed solution, i.e., the pH of the reaction, is preferably 7.5 to 12.0, more preferably 8.5 to 11.0, and even more preferably 9.5 to 10.0.
In order to improve the appearance of a final product, complete and refine the preparation process, the alkali (precipitator) is preferably alkali liquor, and the concentration of the alkali liquor is preferably 1.5-6.5 mol/L, more preferably 2.5-5.5 mol/L, and more preferably 3.5-4.5 mol/L.
The invention has no special limitation on other conditions of the reaction, and the conditions of the reaction known by the technicians in the field can be selected and adjusted by the technicians in the field according to the production condition, the product performance and the quality requirement, the invention ensures and regulates the appearance of the final product, and the preparation process is complete and refined, and the reaction time is preferably 4-36 h, more preferably 10-30 h, and more preferably 15-25 h. The reaction temperature is preferably 40-70 ℃, more preferably 45-65 ℃, and more preferably 50-60 ℃.
The adding mode is not particularly limited by the invention, and the adding mode is known by the technicians in the field, and the technicians in the field can select and adjust according to the production condition, the product performance and the quality requirement, and the adding is preferably slow adding or dropwise adding in order to improve the appearance of the final product, complete and optimize the process. The speed of the slow addition or the dropping is not particularly limited in the present invention, and the speed of the slow addition or the dropping is known to those skilled in the art, and the person skilled in the art can select and adjust the speed according to the production situation, the product performance and the quality requirement.
And then, continuously adding the mixed solution, the complexing agent and the alkali into the first mixed solution obtained in the step, and reacting again to obtain a second mixed solution. And continuously adding the mixed solution, the complexing agent and the alkali into the reaction system obtained in the step (a), and reacting again to obtain a second mixed solution. The mixed solution is the mixed solution obtained in the step 1).
The selection of the complexing agent in the above step is not particularly limited in the present invention, and may be a conventional complexing agent for such reaction, which is well known to those skilled in the art, and can be selected and adjusted by those skilled in the art according to the production situation, product performance and quality requirements, and the complexing agent in the present invention is preferably selected from one or more of ammonia, ammonium bicarbonate, ammonium carbonate, ammonium phosphate, diammonium hydrogen phosphate, ammonium nitrate and urea, more preferably from ammonia, ammonium bicarbonate, ammonium carbonate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium nitrate or urea, and most preferably from ammonia.
The amount of the complexing agent used in the above steps is not particularly limited in the present invention, and may be the amount of the conventional complexing agent used in such reactions, which is well known to those skilled in the art, and may be selected and adjusted by those skilled in the art according to the production situation, product performance and quality requirements, and in step 3) of the present invention, the ratio of the number of moles of the complexing agent to the total number of moles of the nickel salt, manganese salt and/or aluminum salt, and cobalt salt is preferably (5-20): 1, more preferably (7-18): 1, more preferably (10-15): 1.
in order to improve the appearance of a final product, complete and refine the preparation process, the complexing agent in the step is preferably a complexing agent solution, and the concentration of the complexing agent solution in the step is preferably 0.1-3 mol/L, more preferably 0.5-2.5 mol/L, and more preferably 1-2 mol/L.
The selection of the base for the above steps is not particularly limited in the present invention, and may be a base well known to those skilled in the art, and those skilled in the art can select and adjust the base according to the production situation, product performance and quality requirements, and the base in the present invention is preferably one or more selected from lithium hydroxide, sodium hydroxide and potassium hydroxide, more preferably lithium hydroxide, sodium hydroxide or potassium hydroxide, and most preferably sodium hydroxide.
The amount of the alkali used in the above steps is not particularly limited, and those skilled in the art can select and adjust the alkali used in the above steps according to the production conditions, product performance, and quality requirements. In the step 3), the pH of the second mixed solution, i.e., the pH of the re-reaction, is preferably 9.5 to 13.0, more preferably 10 to 12.5, more preferably 10.5 to 12.0, and more preferably 11.0 to 11.5.
In order to further improve the regulation effect and ensure the appearance of a final product, the pH value of the secondary reaction is preferably 0.25-2 higher than that of the reaction, more preferably 0.5-1.7, more preferably 0.7-1.5, and more preferably 1-1.2.
In order to improve the appearance of a final product, complete and refine the preparation process, the alkali (precipitant) in the step is preferably alkali liquor, and the concentration of the alkali liquor in the step is preferably 1.5-6.5 mol/L, more preferably 2.5-5.5 mol/L, and more preferably 3.5-4.5 mol/L.
The invention has no special limitation on other conditions of the secondary reaction, and the conditions of the secondary reaction are known by the technical personnel in the field, and the technical personnel in the field can select and adjust the conditions according to the production condition, the product performance and the quality requirement, the invention ensures and regulates the appearance of the final product, and completes and refines the preparation process, and the time of the secondary reaction is preferably 36-50 h, more preferably 40-47 h, and more preferably 42-45 h. The temperature of the secondary reaction is preferably 45-65 ℃, more preferably 48-62 ℃, and more preferably 50-60 ℃.
The mode of adding continuously is not particularly limited by the invention, and the adding mode known by the technicians in the field can be adopted, and the technicians in the field can select and adjust the adding mode according to the production condition, the product performance and the quality requirement. The speed of the slow addition or the dropping is not particularly limited in the present invention, and the speed of the slow addition or the dropping is known to those skilled in the art, and the person skilled in the art can select and adjust the speed according to the production situation, the product performance and the quality requirement.
Finally, aging the second mixed solution obtained in the step to obtain the precursor of the anode material.
The aging mode and conditions are not particularly limited, and the aging mode and conditions are known by the skilled in the art, and can be selected and adjusted by the skilled in the art according to the production condition, the product performance and the quality requirement, and the aging time is preferably 20-40 h, more preferably 23-38 h, more preferably 25-35 h, and more preferably 27-32 h.
In order to improve the quality of the final product, optimize and complete process flow, the method preferably further comprises a post-treatment step after aging. The post-treatment of the invention preferably comprises one or more of washing, dewatering and drying, more preferably multiple washing, multiple dewatering and drying, more preferably multiple washing and dewatering in sequence, and finally drying.
The improved coprecipitation reaction of the present invention can be summarized into 3 steps:
firstly, generating a multilayer hexagonal flaky positive electrode material hydroxide precursor;
then, growing a granular positive electrode material hydroxide precursor from the multilayer hexagonal flaky positive electrode material hydroxide precursor by regulation and control;
and finally, aging to obtain the uniform multilayer hexagonal flaky and granular composite anode material hydroxide precursor.
The invention is a complete and optimized process, and the preparation steps can be specifically as follows when preparing the quaternary anode material:
mixing nickel salt, cobalt salt and manganese salt to obtain a mixed solution, which is a first mixed salt solution. The total concentration of nickel salt, cobalt salt and manganese salt in the mixed solution is 1-3.5 mol/L.
Preparing a second salt solution, namely an aluminum salt solution, wherein the concentration of the aluminum salt solution is 0.1-2 mol/L;
mixing the first mixed solution, the second salt solution, a sodium hydroxide solution with the concentration of 1.5-6.5 mol/L and an ammonia water solution with the concentration of 0.1-3 mol/L to obtain a second mixed solution, and adjusting the flow rate of the sodium hydroxide solution to enable the pH value of the second mixed solution to be 7.5-12.0. The second solution was reacted to continuously obtain a precursor of a hydroxide of a positive electrode material having spherical particles of a multilayer hexagonal plate-like composition represented by general formula (I).
Continuously mixing the first mixed solution, the second salt solution, a sodium hydroxide solution with the concentration of 1.5-6.5 mol/L and an ammonia water solution with the concentration of 0.1-3 mol/L, adjusting the flow rate of the sodium hydroxide solution to enable the pH of the mixed solution to be 9.5-13.0, and continuously obtaining a granular positive electrode material hydroxide precursor represented by the general formula (I) after the secondary reaction; and continuously aging to obtain the uniform multilayer hexagonal flaky positive electrode material hydroxide precursor represented by the general formula (I) and the positive electrode material hydroxide precursor compounded by the granular positive electrode material hydroxide precursor.
The preparation method of the precursor of the cathode material mainly comprises the steps of preparing a salt solution of three materials of nickel, cobalt and aluminum, preparing a precipitator solution with the same molar concentration as the salt solution and a complexing agent solution with a certain concentration according to a certain speed, dripping the three solutions into a reaction kettle to form a specific reaction system, and simultaneously controlling the pH, the temperature and the time in the later reaction stage to generate nano microsphere particles to obtain spherical particles formed by a plurality of layers of hexagonal plates, and depositing hydroxide precursors of the spherical nanoparticles on the hexagonal plates and in the gaps. The preparation method has simple process, the particle size of the precursor particles is controllable and uniform, the morphology is regular, the tap density is high, and certain gaps exist among the hexagonal sheets, so that the structure is kept better in the subsequent sintering process, and lithium ion diffusion is facilitated. The preparation process provided by the invention is improved, and the prepared anode material precursor is regular in shape, uniform in components and high in tap density, and is suitable for industrial batch production.
The invention provides a positive electrode material, which has a general formula shown as a formula (II):
Li1+wNixCoyMnzAl1-x-y-zO2 (II)，
wherein x is more than 0 and less than 1, y is more than 0 and less than 1, x + y is less than 1, z is more than or equal to 0 and less than 1, x + y + z is less than or equal to 1, and w is more than or equal to-0.5 and less than or equal to 0.5;
the anode material is spherical particles formed by anode material hexagonal plates, and the anode material nano particles are compounded on the anode material hexagonal plates.
In the present invention, the selection and proportion of the materials in the positive electrode material and the corresponding preferred principles thereof are preferably consistent with the selection and proportion of the materials in the positive electrode material precursor and the preparation method thereof and the corresponding preferred principles thereof, if no particular reference is made, and thus no further description is provided herein.
The number of moles of Li, i.e. 1+ w, is preferably-1.5 to 1.5, more preferably-1.3 to 1.3, more preferably-1.1 to 1.1, and most preferably 1.
The positive electrode material is preferably prepared by heat treatment of the positive electrode material precursor according to any one of the above technical schemes or the positive electrode material precursor prepared by the preparation method according to any one of the above technical schemes and lithium salt. The temperature of the heat treatment in the invention is preferably 725 ℃ to 1150 ℃, more preferably 850 ℃ to 1050 ℃, and more preferably 900 ℃ to 1000 ℃.
The invention has no particular limitation on the composition mode of the cathode material hexagonal plate assembled into spherical particles (or spheroidal particles), and the cathode material hexagonal plate assembled into spherical particles (or spheroidal particles) can be prepared in a conventional composition mode well known to those skilled in the art, and the person skilled in the art can select and adjust the cathode material according to the application condition, the product performance and the quality requirement, and the composition of the invention is preferably formed by stacking; the hexagonal sheets of the cathode material can be self-assembled into a multilayer body by multiple sheets, and the multilayer body is stacked to form spherical particles, wherein single-layer hexagonal sheets are also mixed. That is, the hexagonal sheets of the positive electrode material of the present invention preferably include a multilayer body composed of a plurality of hexagonal sheets, or a multilayer body composed of a plurality of hexagonal sheets and a single hexagonal sheet.
The number of layers of the multilayer is not particularly limited, and is determined by a conventional number of layers known to those skilled in the art, and the number of layers of the multilayer can be selected and adjusted by those skilled in the art according to application conditions, product performance and quality requirements, and is preferably 2-50 layers, more preferably 12-40 layers, and more preferably 22-30 layers.
The thickness of the multilayer hexagonal sheet, i.e. the thickness of the multilayer body, is not particularly limited, and can be selected and adjusted by the skilled in the art according to the application, product performance and quality requirements, and the thickness of the multilayer hexagonal sheet is preferably 100-300 nm, more preferably 150-250 nm, and more preferably 180-230 nm.
The stacked multilayer bodies of the present invention have voids between them, and more particularly, the present invention has voids between the individual sheets in the structure of a single multilayer body, and the voids between the sheets of the multilayer hexagonal sheets of the present invention. The positive electrode material nano-particles are compounded in the gaps among the stacked multilayer bodies, and also compounded on the surfaces of the multilayer hexagonal plates and the lamellar gaps of the single multilayer bodies.
The present invention is not particularly limited in the form of the composite, and may be defined as a composite known to those skilled in the art, and the present invention is preferably deposited, grown, filled, clad, modified, layered or generated, more preferably deposited, grown or filled, and most preferably deposited or filled.
The ratio of the hexagonal plates to the nanoparticles is not particularly limited in the present invention, and may be a conventional ratio well known to those skilled in the art, and those skilled in the art may select the ratio according to actual production conditions, product conditions, and product performance, and the mass ratio of the hexagonal plates of the positive electrode material to the nanoparticles of the positive electrode material in the present invention is preferably 10: (1-5), more preferably 10: (1.5 to 4.5), more preferably 10: (2-4), more preferably 10: (2.5-3.5).
The particle size of the nanoparticles is not particularly limited, and can be selected and adjusted by the skilled in the art according to the application, product performance and quality requirements, and is preferably 100-300 nm, more preferably 120-280 nm, more preferably 150-250 nm, and more preferably 180-230 nm. The shape of the nanoparticles is not particularly limited in the present invention, and may be the shape of conventional nanoparticles well known to those skilled in the art, and those skilled in the art can select and adjust the shape according to the application, product performance and quality requirements, and the nanoparticles of the present invention are preferably irregular-shaped nanoparticles, and may be spherical, cubic or polygonal.
The particle size of the spherical particles is not particularly limited, and can be selected and adjusted according to the application condition, product performance and quality requirements by a person skilled in the art according to the particle size of a conventional positive electrode material precursor well known by the person skilled in the art, and the particle size of the spherical particles is preferably 5-15 μm, more preferably 7-13 μm, and more preferably 9-11 μm.
The steps of the invention provide a cathode material, hexagonal sheets are stacked to form primary particles (multilayer body), gaps are formed among layers of the multilayer body, nano particles are deposited on the surfaces of the layers of the multilayer body and in the gaps, and a plurality of multilayer bodies and single hexagonal sheets are stacked to form the cathode material of the lithium ion battery.
According to the invention, the precursor of the positive electrode material obtained in the previous step is mixed with lithium salt for heat treatment, the secondary spherical particle structure formed by the multilayer hexagonal sheet and the spherical particles on the surface of the multilayer hexagonal sheet in the precursor is well preserved, the spherical particles on the hexagonal sheet surface can effectively improve the processing performance of the positive electrode material, improve the structural stability of the positive electrode material, and improve the cycle performance of the positive electrode material, and meanwhile, the spherical particles on the hexagonal sheet surface increase the specific surface area of the material, reduce the internal resistance in the material cycle process, and improve the rate capability of the material.
The invention also provides a lithium ion battery which comprises the anode material in any one of the technical schemes.
The structure of the lithium ion battery is not particularly limited in the present invention, and may be the structure of a conventional lithium ion battery well known to those skilled in the art, and those skilled in the art may select and adjust the structure according to the application, product performance and quality requirements, and the lithium ion battery of the present invention preferably includes a positive electrode, a negative electrode, a separator and an electrolyte. The positive electrode preferably includes a positive electrode active material, a conductive agent, a binder, a solvent, a current collector, and the like. The positive electrode active material is preferably the ternary positive electrode material or the quaternary positive electrode material.
The invention provides a positive electrode material precursor, a preparation method thereof, a positive electrode material and a lithium ion battery. The invention starts from the precursor of the anode material, creatively obtains the precursor of the ternary or quaternary anode material, hexagonal tablets form spherical particles, nanoparticles of the precursor are compounded on the hexagonal tablets of the precursor and in the gaps of the hexagonal tablets, and secondary spherical particles formed by the multilayer hexagonal tablets and the nanoparticles on the surface of the multilayer hexagonal tablets have complete and uniform structure, the nanoparticles on the hexagonal tablet surface can effectively improve the processing performance of the anode material, improve the structural stability of the anode material and improve the cycle performance of the anode material, and meanwhile, the nanoparticles on the hexagonal tablet surface increase the specific surface area of the material, reduce the internal resistance of the material in the cycle process and improve the rate capability of the material. The preparation method has simple process and mild conditions, and is suitable for large-scale production and application
Experimental results show that the lithium ion battery cathode material prepared by the invention has excellent processability and good cycle performance and rate capability, the 0.1C discharge capacity is 194mAh/g, the 5C discharge capacity is 162mAh/g, and the capacity retention rate of 60 circles is 95%.
For further illustration of the present invention, the following will describe in detail a cathode material precursor, a preparation method thereof, a cathode material and a lithium ion battery provided by the present invention with reference to examples, but it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and the detailed embodiments and specific operation procedures are given only for further illustration of the features and advantages of the present invention, not for limitation of the claims of the present invention, and the scope of protection of the present invention is not limited to the following examples.
The starting materials in the following examples are all commercially available products.
Example 1
(1) Respectively weighing 21.56kg, 2.8kg and 13.5kg of nickel sulfate, cobalt sulfate and manganese sulfate according to chemical molecular formula LiNi0.82Co0.1Mn0.08O2The solution is stirred and dissolved in deionized water to prepare a mixed salt solution with the concentration of 2 mol/L;
(2) weighing 35.6kg of sodium hydroxide, stirring and dissolving in deionized water to prepare 8mol/L sodium hydroxide solution used as a precipitator;
(3) measuring 3400ml of ammonia water, diluting the ammonia water with deionized water, and preparing into 2mol/L ammonia water solution which is used as a complexing agent;
(4) and (3) heating the water bath in the reaction kettle to 55 ℃ at constant temperature by using a direct electric heating mode, slowly and dropwise adding the 3 prepared solutions into the reaction kettle respectively, controlling the pH value of the reaction kettle to be 11.3, and reacting for 35 hours.
(5) Continuously dropwise adding the 3 prepared solutions into a reaction kettle respectively, adjusting the flow of ammonia water and the flow of sodium hydroxide to stabilize the pH value at 12.3, and reacting for 40 hours; and aging for 40h to obtain the multilayer hexagonal flaky and granular composite nickel-cobalt-manganese hydroxide precursor.
(6) And (3) washing the coprecipitation product for multiple times, dehydrating and drying to obtain the nickel-cobalt-manganese ternary material precursor particles.
The nickel-cobalt-manganese ternary material precursor particles prepared in embodiment 1 of the invention are characterized.
Referring to fig. 1, fig. 1 is an SEM scanning electron microscope image of the nickel-cobalt-manganese ternary material precursor prepared in example 1 of the present invention at a scale of 5 μm.
Referring to fig. 2, fig. 2 is an SEM scanning electron microscope image of the nickel-cobalt-manganese ternary material precursor prepared in example 1 of the present invention at a scale of 1 μm.
As can be seen from fig. 1 and 2, the particle size distribution and morphology of the precursor particles are regular, multiple hexagonal plates of the precursor of the positive electrode material are self-assembled into a multilayer body, the multilayer body is stacked to form spherical particles, and nanoparticles of the precursor of the positive electrode material are deposited on the hexagonal plates. The stacked multilayer bodies have gaps between them and the individual sheets of the single multilayer body have gaps between them, and nanoparticles are deposited in the gaps between the stacked multilayer bodies and also on the surfaces of the multilayer hexagonal plates and in the sheet gaps of the single multilayer body.
The detection result of the nickel-cobalt-manganese ternary material precursor prepared in the embodiment 1 of the invention shows that the tap density is 2.7g/ml, and the D50 is 8 μm.
Mixing the precursor particles with lithium carbonate, and calcining at high temperature to obtain the positive electrode material LiNi which is not subjected to modification treatment such as doping and coating0.82Co0.1Mn0.08O2And assembling the half cell without any other modification, and performing electrochemical performance test.
Referring to fig. 3, fig. 3 is an SEM scanning electron microscope image of the nickel-cobalt-manganese ternary cathode material prepared in example 1 of the present invention.
As can be seen from fig. 3, the hexagonal pieces of the cathode material are self-assembled into a multilayer body, the multilayer body is stacked again to form spherical particles, and the cathode material nanoparticles are deposited on the hexagonal pieces. The stacked multilayer bodies have gaps between them and the individual sheets of the single multilayer body have gaps between them, and nanoparticles are deposited in the gaps between the stacked multilayer bodies and also on the surfaces of the multilayer hexagonal plates and in the sheet gaps of the single multilayer body.
The performance detection result shows that the 0.1C discharge capacity is 194 mAh/g; 0.2C capacity 190; the 0.5C capacity is 185 mAh/g; the 1C capacity is 182 mAh/g; the 5C discharge capacity was 162 mAh/g. The capacity retention rate at 60 cycles is 95%.
Example 2
(1) Weighing nickel sulfate, cobalt sulfate and manganese sulfate respectively at 15.77kg, 5.63kg and 3.38kg, and obtaining LiNi according to chemical molecular formula0.6Co0.2Mn0.2O2The solution is stirred and dissolved in deionized water to prepare a mixed salt solution with the concentration of 2 mol/L;
(2) weighing 17.8kg of sodium hydroxide, stirring and dissolving in deionized water to prepare 4mol/L sodium hydroxide solution used as a precipitator;
(3) measuring 3400ml of ammonia water, diluting the ammonia water with deionized water, and preparing into 2mol/L ammonia water solution which is used as a complexing agent;
(4) and (3) heating the water bath in the reaction kettle to 55 ℃ at constant temperature by using a direct electric heating mode, slowly and dropwise adding the 3 prepared solutions into the reaction kettle respectively, controlling the pH value of the reaction kettle to be 11.25, and reacting for 30 hours.
(5) Continuously dropwise adding the 3 prepared solutions into the reaction kettle respectively, adjusting the flow of ammonia water and the flow of sodium hydroxide to stabilize the pH value at 11.78, and reacting for 40 h; and aging for 20h to obtain the multilayer hexagonal flaky and granular composite nickel-cobalt-manganese hydroxide precursor.
(6) And (3) washing the coprecipitation product for multiple times, dehydrating and drying to obtain the nickel-cobalt-manganese ternary material precursor particles.
The detection result of the nickel-cobalt-manganese ternary material precursor prepared in the embodiment 2 of the invention shows that the tap density is 2.4g/ml, and the D50 is 10 μm.
Mixing the precursor particles with lithium carbonate, and calcining at high temperature to obtain the positive electrode material LiNi which is not subjected to modification treatment such as doping and coating0.6Co0.2Mn0.2O2And assembling the semi-cell to carry out electrochemical performance test.
Example 3
(1) Respectively weighing 13.14kg, 56.23kg and 50.70kg of nickel sulfate, cobalt sulfate and manganese sulfate according to chemical molecular formula LiNi0.5Co0.2Mn0.3O2The molar ratio concentration of (1) is stirred and dissolved in deionized water to be configured into 2mA mixed salt solution of ol/L;
(2) weighing 8.9kg of sodium hydroxide, stirring and dissolving in deionized water to prepare 2mol/L sodium hydroxide solution used as a precipitator;
(3) weighing 1700ml of ammonia water, diluting with deionized water, and preparing into 1mol/L ammonia water solution which is used as a complexing agent;
(4) heating the water bath in the reaction kettle to 60 ℃ in a constant temperature manner by direct electric heating, respectively and slowly dripping the 3 prepared solutions into the reaction kettle, controlling the pH value of the reaction kettle to be 10.5, and reacting for 30 hours.
(5) Continuously dropwise adding the 3 prepared solutions into the reaction kettle respectively, adjusting the flow of ammonia water and the flow of sodium hydroxide to stabilize the pH value at 11.3, and reacting for 40 h; and aging for 30h to obtain the multilayer hexagonal flaky and granular composite nickel-cobalt-manganese hydroxide precursor.
(6) And (3) washing the coprecipitation product for multiple times, dehydrating and drying to obtain the nickel-cobalt-manganese ternary material precursor particles.
The detection result of the nickel-cobalt-manganese ternary material precursor prepared in the embodiment 3 of the invention shows that the tap density is 2.1g/ml, and the D50 is 12 μm.
Mixing the precursor particles with lithium carbonate, and calcining at high temperature to obtain the positive electrode material LiNi which is not subjected to modification treatment such as doping and coating0.5Co0.2Mn0.3O2And assembling the semi-cell to carry out electrochemical performance test.
Example 4
(1) Nickel sulfate, cobalt sulfate and aluminum sulfate are respectively weighed to be 21.02kg, 4.2kg and 1.78kg of LiNi0.8Co0.1Al0.2O2The solution is stirred and dissolved in deionized water to prepare a mixed salt solution with the concentration of 2 mol/L;
(2) weighing 17.8kg of sodium hydroxide, stirring and dissolving in deionized water to prepare 4mol/L sodium hydroxide solution used as a precipitator;
(3) measuring 3400ml of ammonia water, diluting the ammonia water with deionized water, and preparing into 2mol/L ammonia water solution which is used as a complexing agent;
(4) and (3) heating the water bath in the reaction kettle to 50 ℃ at constant temperature by using a direct electric heating mode, slowly and dropwise adding the 3 prepared solutions into the reaction kettle respectively, controlling the pH value of the reaction kettle to be 9.25, and reacting for 35 hours.
(5) Continuously dropwise adding the 3 prepared solutions into a reaction kettle respectively, adjusting the flow of ammonia water and the flow of sodium hydroxide to stabilize the pH value at 10.78, and reacting for 20 hours; and aging for 35h to obtain the multilayer hexagonal flaky and granular composite nickel-cobalt-aluminum hydroxide precursor.
(6) And (3) washing the coprecipitation product for multiple times, dehydrating and drying to obtain the nickel-cobalt-aluminum ternary material precursor particles.
The detection result of the nickel-cobalt-aluminum ternary material precursor prepared in the embodiment 4 of the invention shows that the tap density is 2.3g/ml, and the D50 is 13 μm.
Mixing the precursor particles with lithium carbonate, and calcining at high temperature to obtain the positive electrode material LiNi which is not subjected to modification treatment such as doping and coating0.8Co0.1Al0.2O2And assembling the semi-cell to carry out electrochemical performance test.
Example 5
(1) According to the formula LiNi0.8Co0.1Al0.1O2Respectively weighing 21.02kg and 4.2kg of nickel sulfate and cobalt sulfate, preparing 2mol/L nickel-cobalt salt solution, and weighing 3.2kg of sodium aluminate to dissolve and prepare aluminum salt solution;
(2) weighing 35.6kg of sodium hydroxide, stirring and dissolving in deionized water to prepare 8mol/L sodium hydroxide solution used as a precipitator;
(3) measuring 3400ml of ammonia water, diluting the ammonia water with deionized water, and preparing into 2mol/L ammonia water solution which is used as a complexing agent;
(4) heating the water bath in the reaction kettle to 53 ℃ in a constant temperature manner by direct electric heating, respectively and slowly dripping the 4 prepared solutions into the reaction kettle, controlling the pH value of the reaction kettle to be 11.25, and reacting for 10 hours.
(5) Continuously dropwise adding the 4 prepared solutions into a reaction kettle respectively, adjusting the flow of ammonia water and the flow of sodium hydroxide to stabilize the pH value at 11.78, and reacting for 45 hours; and aging for 36h to obtain the multilayer hexagonal flaky and granular composite nickel-cobalt-aluminum hydroxide precursor.
(6) And (3) washing the coprecipitation product for multiple times, dehydrating and drying to obtain the nickel-cobalt-aluminum ternary material precursor particles.
The detection result of the nickel-cobalt-aluminum ternary material precursor prepared in the embodiment 5 of the invention shows that the tap density is 2.5g/ml, and the D50 is 10 μm.
Mixing the precursor particles with lithium carbonate, and calcining at high temperature to obtain the positive electrode material LiNi which is not subjected to modification treatment such as doping and coating0.8Co0.1Al0.1O2And assembling the semi-cell to carry out electrochemical performance test.
Example 6
(1) Respectively weighing 20.34kg, 2.8kg and 13.5kg of nickel sulfate, cobalt sulfate and manganese sulfate according to chemical molecular formula LiNi0.80Co0.1Mn0.08Al0.02O2The solution is stirred and dissolved in deionized water to prepare a mixed salt solution with the concentration of 2 mol/L; then weighing 1.78Kg of sodium aluminate according to the above molecular formula ratio, dissolving and preparing into sodium aluminate solution.
(2) Weighing 17.8kg of sodium hydroxide, stirring and dissolving in deionized water to prepare 4mol/L sodium hydroxide solution used as a precipitator;
(3) measuring 3400ml of ammonia water, diluting the ammonia water with deionized water, and preparing into 2mol/L ammonia water solution which is used as a complexing agent;
(4) heating the water bath in the reaction kettle to 50 ℃ in a constant temperature manner by direct electric heating, respectively and slowly dripping the 4 prepared solutions into the reaction kettle, controlling the pH value of the reaction kettle to be 9.25, and reacting for 18 hours.
(5) Continuously dropwise adding the 4 prepared solutions into a reaction kettle respectively, adjusting the flow of ammonia water and the flow of sodium hydroxide to stabilize the pH value at 10.78, and reacting for 40 hours; aging for 24h to obtain multilayer hexagonal flaky and granular composite LiNi0.80Co0.1Mn0.08Al0.02O2Nickel cobalt manganese aluminium hydroxideAnd (3) precursor.
(6) And (3) washing the coprecipitation product for multiple times, dehydrating and drying to obtain the precursor particles of the nickel-cobalt-manganese-aluminum quaternary material.
The detection result of the nickel-cobalt-manganese-aluminum quaternary material precursor prepared in the embodiment 6 of the invention shows that the tap density is 2.0g/ml, and the D50 is 16 μm.
Mixing the precursor particles with lithium carbonate, and calcining at high temperature to obtain the positive electrode material LiNi which is not subjected to modification treatment such as doping and coating0.80Co0.1Mn0.08Al0.02O2And assembling the semi-cell to carry out electrochemical performance test.
The foregoing detailed description of the present invention provides a precursor for positive electrode material, a method for preparing the same, a positive electrode material, and a lithium ion battery, and the principles and embodiments of the present invention are described herein with reference to specific examples, which are provided to facilitate understanding of the methods and their core concepts, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims (10)

1. A precursor of a positive electrode material, characterized by having a general formula represented by formula (I):
NixCoyMnzAl1-x-y-z(OH)2（I）；
wherein x is more than 0 and less than 1, y is more than 0 and less than 1, x + y is less than 1, z is more than or equal to 0 and less than 1, and x + y + z is less than or equal to 1;
the positive electrode material precursor is spherical particles formed by hexagonal pieces of the positive electrode material precursor, and the hexagonal pieces of the positive electrode material precursor are compounded with positive electrode material precursor nano particles;
the hexagonal plates of the positive electrode material precursor comprise a multilayer body consisting of a plurality of layers of hexagonal plates, or a multilayer body consisting of a plurality of layers of hexagonal plates and a single-layer hexagonal plate;
gaps are reserved among the layers of the multilayer hexagonal sheets;
the anode material precursor nano particles are compounded on the surfaces of the multilayer hexagonal plates and in the gaps of the layers.
2. The precursor of a positive electrode material according to claim 1, wherein the number of the plurality of layers is 2 to 50;
the particle size of the nano particles is 100-300 nm;
the mass ratio of the positive electrode material precursor hexagonal piece to the positive electrode material precursor nano particles is 10: (1-5).
3. The positive electrode material precursor according to claim 2, wherein the composition is formed as a stack;
the thickness of the multilayer hexagonal sheet is 50-200 nm.
4. A method for producing a precursor for a positive electrode material according to any one of claims 1 to 3, comprising the steps of:
1) mixing nickel salt, manganese salt and/or aluminum salt, cobalt salt and water to obtain a mixed solution;
2) adding the mixed solution, a complexing agent and alkali, and reacting to obtain a first mixed solution;
3) continuously adding the mixed solution, the complexing agent and the alkali into the first mixed solution obtained in the step, and reacting again to obtain a second mixed solution;
in the step 3), the ratio of the mole number of the complexing agent to the total mole number of the nickel salt, the manganese salt and/or the aluminum salt and the cobalt salt is (5-20): 1;
the pH value of the secondary reaction is 9.5-13.0;
the pH value of the secondary reaction is 0.25-2 higher than that of the reaction;
the secondary reaction time is 36-50 h;
the temperature of the secondary reaction is 45-65 ℃;
4) and aging the second mixed solution obtained in the step to obtain the precursor of the anode material.
5. The preparation method according to claim 4, wherein the step 1) is specifically:
mixing nickel salt, manganese salt, cobalt salt and water to obtain a primary mixed solution;
mixing aluminum salt and water to obtain an aluminum salt solution; the molar concentration of the aluminum salt solution is 0.1-2 mol/L;
and mixing the primary mixed solution and the aluminum salt solution to obtain a mixed solution.
6. The method according to claim 4, wherein the total molar concentration of the manganese salt and/or the aluminum salt, the nickel salt, and the cobalt salt in the mixed solution is 1 to 3.5 mol/L;
the alkali is selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide;
the complexing agent is selected from one or more of ammonia water, ammonium bicarbonate, ammonium carbonate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium nitrate and urea;
in the step 2), the ratio of the mole number of the complexing agent to the total mole number of the nickel salt, the manganese salt and/or the aluminum salt and the cobalt salt is (1-10): 1;
the pH value of the reaction is 7.5-12.0;
the reaction time is 4-36 h;
the reaction temperature is 40-70 ℃.
7. The preparation method according to claim 4, wherein the aging time is 20-40 h.
8. A positive electrode material characterized by having a general formula as shown in formula (II):
Li1+wNixCoyMnzAl1-x-y-zO2 （II），
wherein x is more than 0 and less than 1, y is more than 0 and less than 1, x + y is less than 1, z is more than or equal to 0 and less than 1, x + y + z is less than or equal to 1, and w is more than or equal to-0.5 and less than or equal to 0.5;
the positive electrode material is spherical particles consisting of positive electrode material hexagonal plates, and positive electrode material nano particles are compounded on the positive electrode material hexagonal plates;
the hexagonal plates of the positive electrode material precursor comprise a multilayer body consisting of a plurality of layers of hexagonal plates, or a multilayer body consisting of a plurality of layers of hexagonal plates and a single-layer hexagonal plate;
gaps are reserved among the layers of the multilayer hexagonal sheets;
the anode material precursor nano particles are compounded on the surfaces of the multilayer hexagonal plates and in the gaps of the layers.
9. The positive electrode material according to claim 8, wherein the positive electrode material is obtained by heat-treating a positive electrode material precursor according to any one of claims 1 to 3 or a positive electrode material precursor prepared by the preparation method according to any one of claims 4 to 7 with a lithium salt;
the temperature of the heat treatment is 725-1150 ℃.
10. A lithium ion battery comprising the positive electrode material according to claim 8 or 9.
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