CN110828797A - Positive electrode material, preparation method thereof and battery - Google Patents

Positive electrode material, preparation method thereof and battery Download PDF

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Publication number
CN110828797A
CN110828797A CN201911043836.9A CN201911043836A CN110828797A CN 110828797 A CN110828797 A CN 110828797A CN 201911043836 A CN201911043836 A CN 201911043836A CN 110828797 A CN110828797 A CN 110828797A
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core
shell
lithium
cobalt
positive electrode
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刘学良
夏良俊
王耐清
徐海平
刘昆
林涛
李世达
王翔
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Soundon 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/52—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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to a positive electrode material, a preparation method thereof and a battery, wherein the positive electrode material is of a core-shell structure with a coating layer on the surface, the core-shell structure comprises an inner core and a shell layer coated on the surface of the inner core, the inner core is made of nickel cobalt lithium manganate, the shell layer is made of lithium cobaltate, and the coating layer is made of lithium niobate and/or lithium titanate. In the cathode material, the coating layer endows the material with excellent ionic conductivity, the material can have good interface compatibility with sulfide solid electrolyte, the interface problem is solved, the core material can provide high gram capacity, and the shell layer endows the material with excellent rate performance, so that the cathode material has excellent electrochemical performance. When the cathode material is applied to the all-solid-state lithium ion battery, the discharge specific capacity, the cycle and the rate performance of the battery can be effectively improved.

Description

Positive electrode material, preparation method thereof and battery
Technical Field
The invention relates to the technical field of energy materials, in particular to a positive electrode material, a preparation method thereof and a battery.
Background
Lithium ion batteries are receiving increasing attention as a new type of energy storage device due to their high energy density and their higher operating voltage. At present, lithium ion battery electrolyte on the market mainly takes organic liquid electrolyte as a main component, the leakage phenomenon is easy to occur in the use process of the battery, and an organic solvent is flammable and easy to oxidize, so that serious potential safety hazard exists in the use process. Compared with the currently used liquid electrolyte, the solid electrolyte does not need a solvent as a dispersing agent and can be used as a diaphragm, so that the weight of the battery cell can be effectively reduced, the battery is developed towards the direction of light weight, and the energy density of the battery can be further improved.
Currently, much research is conducted on PEO polymer electrolytes, which have low ionic conductivity, so that the type of battery still cannot meet practical requirements. And sulfide electrolyte as a novel solid electrolyte having high ionic conductivity (2.5X 10)-2S/cm) to reach or even exceed the level of ionic conductivity of the liquid electrolyte. However, the conventional high nickel cathode material has poor interface compatibility with the solid electrolyte, and is easy to form an interface problem, which results in poor battery performance.
Disclosure of Invention
Based on this, there is a need to provide a positive electrode material having good interface compatibility with a sulfide solid electrolyte.
The utility model provides an anode material, anode material has the nucleocapsid structure of coating for the surface, nucleocapsid structure include the kernel with wrap in the shell on kernel surface, the material of kernel is nickel cobalt lithium manganate, the material of shell is lithium cobaltate, the material of coating is lithium niobate and/or lithium titanate.
The invention designs a core-shell structure anode material with a coating layer on the surface according to the principle of core-shell structure function complementation, wherein nickel cobalt lithium manganate is taken as a core material, and lithium cobaltate (LiCoO) is taken2) Is a shell material, and takes lithium niobate and/or lithium titanate as a coating layer. In the cathode material, the coating layer endows the material with excellent ionic conductivity, the material can have good interface compatibility with sulfide solid electrolyte, the interface problem is solved, the core material can provide high gram capacity, and the shell layer endows the material with excellent rate performance, so that the cathode material has excellent electrochemical performance. When the cathode material is applied to the all-solid-state lithium ion battery, the discharge specific capacity, the cycle and the rate performance of the battery can be effectively improved.
In one embodiment, the molar ratio of the nickel-cobalt-manganese element in the core layer to the cobalt element in the shell layer is (1-x) x, and x is more than or equal to 0.05 and less than or equal to 0.35.
In one embodiment, the molar ratio of the nickel-cobalt-manganese element in the core layer to the cobalt element in the shell layer is (1-x) x, and x is more than or equal to 0.05 and less than or equal to 0.15.
In one embodiment, in the positive electrode material, the mass percentage of the coating layer is 1% to 5%.
In one embodiment, the chemical formula of the lithium nickel cobalt manganese oxide is LiNi0.8Co0.1Mn0.1O2。
The invention also provides a preparation method of the cathode material, which comprises the following steps: mixing a core material solution, a shell material solution, alkali and a complexing agent to perform precursor reaction, then performing aging and solid-liquid separation to obtain a precursor, mixing the precursor with a first lithium source to perform sintering to obtain a core-shell structure material, mixing the core-shell structure material, a second lithium source, an organic solvent and a chelating agent, drying and sintering to obtain the anode material; the core material solution is a mixed salt solution of nickel salt, cobalt salt and manganese salt, the shell material solution is a cobalt salt solution, and the second lithium source is lithium niobate and/or lithium titanate.
In one embodiment, the molar ratio of the nickel, cobalt and manganese salts in the core material solution to the cobalt salt in the shell material solution is (1-x) x, 0.05. ltoreq. x.ltoreq.0.35.
In one embodiment, the mass ratio of the core-shell structure material to the second lithium source is (19-99): 1.
In one embodiment, the nickel salt is nickel sulfate, the cobalt salt is cobalt sulfate, and the manganese salt is manganese sulfate.
The invention also provides a battery which comprises the negative electrode material and the positive electrode material.
Drawings
FIG. 1 is an SEM image of the precursor prepared in example 1;
FIG. 2 is an SEM image of a core-shell structured material prepared in example 1;
fig. 3 is an SEM image of the cathode material prepared in example 1;
FIG. 4 is a diagram showing the first charge and discharge of batteries produced from the positive electrode materials of examples 1 to 3 and comparative examples 1 to 2;
FIG. 5 is a graph showing cycle characteristics of batteries manufactured using the positive electrode materials of examples 1 to 3 and comparative examples 1 to 2;
FIG. 6 is an EDS analysis chart of the core-shell structure material prepared in example 1;
FIG. 7 is an EDS analysis chart of the core-shell structure material prepared in example 2;
fig. 8 is an EDS analysis chart of the core-shell structure material prepared in example 3.
Detailed Description
In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
According to the positive electrode material provided by the embodiment of the invention, the positive electrode material is of a core-shell structure with a coating layer on the surface. The core-shell structure comprises a core and a shell layer coated on the surface of the core, wherein the core is made of lithium nickel cobalt manganese oxide, and the shell layer is made of lithium cobalt oxide (LiCoO)2) The coating layer is made of lithium niobate (LiNbO)3) And/or lithium titanate (Li)4Ti5O12)。
The invention designs a core-shell structure anode material with a coating layer on the surface according to the principle of core-shell structure function complementation, wherein nickel cobalt lithium manganate is taken as a core material, and lithium cobaltate (LiCoO) is taken2) Is a shell material, and takes lithium niobate and/or lithium titanate as a coating layer. In the cathode material, the coating layer endows the material with excellent ionic conductivity, the material can have good interface compatibility with sulfide solid electrolyte, the interface problem is solved, the core material can provide high gram capacity, and the shell layer endows the material with excellent rate performance, so that the cathode material has excellent electrochemical performance. When the cathode material is applied to the all-solid-state lithium ion battery, the discharge specific capacity, the cycle and the rate performance of the battery can be effectively improved.
In one specific example, the molar ratio of the nickel-cobalt-manganese element in the core layer to the cobalt element in the shell layer is (1-x) < x, 0.05 ≦ x ≦ 0.35. Preferably, the molar ratio of the nickel-cobalt-manganese element in the core layer to the cobalt element in the shell layer is (1-x): x, 0.05 ≤ x ≤ 0.15. Theoretically, the gram capacity of the material is reduced due to the fact that the lithium cobaltate is coated on the nickel cobalt lithium manganate material, but according to test data, the gram capacity of the material is not reduced under the condition of a core-shell ratio of about 9:1, and the core-shell ratio of about 9:1 is proved to be capable of guaranteeing that the material has higher gram capacity, so that the battery has higher specific discharge capacity, the specific discharge capacity of a first circle can reach 171.2mAh/g, and the cycle performance is better.
In a specific example, in the positive electrode material, the mass percentage of the coating layer is 1% to 5%, preferably 3%.
In one specific example, the lithium nickel cobalt manganese oxide has the formula LiNi0.8Co0.1Mn0.1O2Compared with other proportions of nickel cobalt lithium manganate, the lithium nickel cobalt manganese has higher gram capacity.
In one specific example, the material of the coating layer is lithium niobate. LiNbO3Compared with Li4Ti5O12Has higher ion conductivity, so that the coating layer is LiNbO3The performance of the battery is better than that of the battery with Li as a coating layer4Ti5O12The properties of the material.
The preparation method of the cathode material of the embodiment of the invention comprises the following steps: mixing the core material solution, the shell material solution, alkali and a complexing agent to perform precursor reaction, then performing aging and solid-liquid separation to obtain a precursor, mixing the precursor with a first lithium source to perform solid-phase sintering to obtain a core-shell structure material, mixing the core-shell structure material, a second lithium source, an organic solvent and a chelating agent, drying and sintering to obtain the cathode material. Wherein the nuclear material solution is a mixed salt solution of nickel salt, cobalt salt and manganese salt, the shell material solution is a cobalt salt solution, and the second lithium source is lithium niobate and/or lithium titanate.
The preparation method of the cathode material adopts a coprecipitation-high temperature solid phase method to synthesize a precursor, and then the precursor is matched with a lithium source to be sintered to obtain the core-shell structure material taking nickel cobalt lithium manganate as a core material and lithium cobaltate as a shell material. And then modifying the core-shell structure material by adopting a coating means, namely coating lithium niobate and/or lithium titanate on the surface of the core-shell structure material by adopting a sol-gel method, so that a buffer layer can be introduced between the core-shell structure material and the electrolyte, and the interface compatibility of the anode material and the sulfide solid electrolyte is further improved. In the cathode material, the coating layer endows the material with excellent ionic conductivity, the material can have good interface compatibility with sulfide solid electrolyte, the interface problem is solved, the core material can provide high gram capacity, and the shell layer endows the material with excellent rate performance, so that the cathode material has excellent electrochemical performance. When the cathode material is applied to the all-solid-state lithium ion battery, the discharge specific capacity, the cycle and the rate performance of the battery can be effectively improved.
In one specific example, the molar ratio of the nickel, cobalt and manganese salts in the core material solution to the cobalt salt in the shell material solution is (1-x): x, 0.05 ≦ x ≦ 0.35. Preferably, the molar ratio of the nickel, cobalt and manganese salts in the solution of the core material to the cobalt salt in the solution of the shell material is (1-x) x, 0.05. ltoreq. x.ltoreq.0.15.
In a specific example, the mass ratio of the core-shell structure material to the second lithium source is (19-99): 1. Preferably, the mass ratio of the core-shell structure material to the second lithium source is (30-40): 1. Preferably, the second lithium source also includes lithium carbonate, so that there is a slight excess of Li over Nb or Ti, which is beneficial for increasing the material capacity and also has certain benefits for cycling.
Alternatively, the salt in the core material solution and the shell material solution may be one or more of a sulfate, a chlorate, and a nitrate, respectively. In one specific example, the nickel salt is nickel sulfate, the cobalt salt is cobalt sulfate, and the manganese salt is manganese sulfate.
In one specific example, the base is one or more of a NaOH solution, a KOH solution, and a CaOH solution, and the complexing agent is ammonia. Optionally, the volume ratio of the alkali to the complexing agent is (7-5) to (3-5).
In a specific example, the precursor reaction has a reaction pH of 10-12, a reaction temperature of 40-60 ℃, a stirring speed of 500-600 rpm, and a protective gas such as nitrogen, argon and the like is introduced during the reaction process to prevent oxidation.
In one specific example, the aging time is 20 hours to 40 hours. Preferably, the first lithium source is one or more of lithium carbonate, lithium hydroxide, and the chelating agent is an organic acid such as citric acid, and the like. Preferably, the sintering temperature of the precursor and the first lithium source is 700-900 ℃, and the sintering time is 8-16 hours. Preferably, the roasting temperature of the core-shell structure material and the second lithium source is 700-900 ℃, and the roasting time is 1-4 hours.
The following are specific examples, and the parts of each example and comparative example which are not described are the same as in example 1 unless otherwise described.
Example 1
Preparing a nuclear material solution with the concentration of 2mol/L according to the molar ratio of Ni to Co to Mn to 8 to 1, wherein the salt is nickel sulfate, cobalt sulfate and manganese sulfate. Preparing a cobalt sulfate solution with the concentration of 2mol/L as a shell material solution.
0.9L of core material solution and 0.1L of shell material solution are respectively taken and added into a reaction kettle in sequence, NaOH solution and ammonia water are added, and the pH value of the reaction kettle is adjusted to be about 11. The concentration of the NaOH solution is 10mol/L, the concentration of the ammonia water is 0.2mol/L, and the volume ratio of the NaOH solution to the ammonia water is 7: 3. Controlling the temperature of the solution to be about 50 ℃, stirring and introducing inert gas for protection. After the reaction liquid is completely added, the stirring speed is reduced, and the reaction liquid is aged for 24 hours. After aging, the precursor is obtained by filtration, washing and drying, as shown in FIG. 1. 78g of Li were added in a molar ratio of Li to M1.05 to 1(M Ni, Co, Mn)2CO3As a lithium source, uniformly mixing, heating the mixed material to 750 ℃ in an oxygen atmosphere, preserving heat for 4h, and preserving heat for 12h at 820 ℃ to obtain the core-shell structure material Li [ (Ni)0.8Co0.1Mn0.1)0.9Co0.1]O2As shown in fig. 2.
Mixing a certain amount of ethanol and deionized water, placing the mixture in a beaker, and weighing a certain amount of LiNbO3And Li2CO3Dissolving in the solution at a molar ratio of Li to Nb of 1.02 to 1, and stirring for 15min on a magnetic stirrer. Adding citric acid as chelating agent into the solution, stirring for 1 hr, and adding Li [ (Ni) as core-shell structure material0.8Co0.1Mn0.1)0.9Co0.1]O2Heating and stirring until a black gel is formed, wherein the core-shell structure material and LiNbO3Is 32.33: 1. Putting the black gel into a drying oven at 100 ℃ for drying for 2h, and then sintering the black gel in a muffle furnace at 800 ℃ in air atmosphere for 2h to volatilize organic matters in the material to obtain LiNbO3Coated Li [ (Ni)0.8Co0.1Mn0.1)0.9Co0.1]O2The positive electrode material has a coating layer with a mass percentage of about 3%, is marked as CS-9-1, and has a charge capacity of 171.2mAh/g as shown in figure 3. As can be seen from a comparison of the SEM images of FIGS. 2 and 3, LiNbO3The surface of the coated material is smoother, and a layer of coating is obviously formed.
Comparative example 1
Adding 1L of nuclear material solution into a reaction kettle, adding NaOH solution and ammonia water, and adjusting the pH value of the reaction kettle to be about 11. The concentration of the NaOH solution is 10mol/L, the concentration of the ammonia water is 0.2mol/L, and the volume ratio of the NaOH solution to the ammonia water is 7: 3. Controlling the temperature of the solution to be about 50 ℃, stirring and introducing inert gas for protection. After the reaction liquid is completely added, the stirring speed is reduced, and the reaction liquid is aged for 24 hours. And after aging, filtering, washing and drying. Adding 78gLi according to the mol ratio of Li to M being 1.05 to 1(M being Ni, Co and Mn)2CO3As lithium source, mixing, heating the mixed material to 750 deg.C in oxygen atmosphere, keeping the temperature for 4h, and keeping the temperature at 820 deg.C for 12h to obtain Li [ Ni ]0.8Co0.1Mn0.1]O2。
Mixing a certain amount of ethanol and deionized water, placing the mixture in a beaker, and weighing a certain amount of LiNbO3And Li2CO3Dissolving in the solution at a molar ratio of Li to Nb of 1.02 to 1, and stirring for 15min on a magnetic stirrer. Adding citric acid as chelating agent into the solution, stirring for 1 hr, adding Li [ Ni ]0.8Co0.1Mn0.1]O2And heating and stirring until a black gel is formed. Putting the black gel into a drying oven at 100 ℃ for drying for 2h, and then sintering the black gel in a muffle furnace at 800 ℃ in air atmosphere for 2h to volatilize organic matters in the material to obtain LiNbO3Coated Li [ Ni ]0.8Co0.1Mn0.1]O2The positive electrode material, labeled C-811, had a charge capacity of 171.1 mAh/g.
Comparative example 2
Adding 1L of shell material solution into a reaction kettle, adding NaOH solution and ammonia water, and adjusting the pH value of the reaction kettle to be about 11. The concentration of NaOH solution is 10mol/L, the concentration of ammonia water is 0.2mol/L, the volume ratio of the NaOH solution to the ammonia water is 7:3, the temperature of the solution is controlled to be about 50 ℃, and the solution is stirred and is protected by introducing inert gas. After the reaction liquid is completely added, the stirring speed is reduced, and the reaction liquid is aged for 24 hours. And after aging, filtering, washing and drying. Adding 78gLi according to the mol ratio of Li to M being 1.05 to 1(M being Ni, Co and Mn)2CO3As a lithium source, uniformly mixing, heating the mixed material to 750 ℃ in an oxygen atmosphere, preserving heat for 4h, and preserving heat for 12h at 820 ℃ to obtain LiCoO2。
Mixing a certain amount of ethanol and deionized water, placing the mixture in a beaker, and weighing a certain amount of LiNbO3And Li2CO3Dissolving in the solution at a molar ratio of Li to Nb of 1.02 to 1, and stirring for 15min on a magnetic stirrer. Adding citric acid as chelating agent into the solution, stirring for 1 hr, and adding LiCoO2And heating and stirring until a black gel is formed. Putting the black gel into a drying oven at 100 ℃ for drying for 2h, and then sintering the black gel in a muffle furnace at 800 ℃ in air atmosphere for 2h to volatilize organic matters in the material to obtain LiNbO3Coated LiCoO2The positive electrode material, labeled S-LCO, had a charge capacity of 118.9 mAh/g.
Example 2
0.8L of core material solution and 0.2L of shell material solution are respectively taken and added into a reaction kettle in sequence, NaOH solution and ammonia water are added, and the pH value of the reaction kettle is adjusted to be about 11. The concentration of the NaOH solution is 10mol/L, the concentration of the ammonia water is 0.2mol/L, and the volume ratio of the NaOH solution to the ammonia water is 7: 3. Controlling the temperature of the solution to be about 50 ℃, stirring and introducing inert gas for protection. After the reaction liquid is completely added, the stirring speed is reduced, and the reaction liquid is aged for 24 hours. And after aging, filtering, washing and drying to obtain the precursor. 78g of Li were added in a molar ratio of Li to M1.05 to 1(M Ni, Co, Mn)2CO3As lithium source, and mixing well under oxygen atmosphereFirstly heating the mixed material to 750 ℃ and preserving heat for 4h, and then preserving heat for 12h at 820 ℃ to obtain the core-shell structure material Li [ (Ni)0.8Co0.1Mn0.1)0.8Co0.2]O2。
Mixing a certain amount of ethanol and deionized water, placing the mixture in a beaker, and weighing a certain amount of LiNbO3And Li2CO3Dissolving in the solution at a molar ratio of Li to Nb of 1.02 to 1, and stirring for 15min on a magnetic stirrer. Adding citric acid as chelating agent into the solution, stirring for 1 hr, and adding Li [ (Ni) as core-shell structure material0.8Co0.1Mn0.1)0.8Co0.2]O2And heating and stirring until a black gel is formed. Putting the black gel into a drying oven at 100 ℃ for drying for 2h, and then sintering the black gel in a muffle furnace at 800 ℃ in air atmosphere for 2h to volatilize organic matters in the material to obtain LiNbO3Coated Li [ (Ni)0.8Co0.1Mn0.1)0.8Co0.2]O2The positive electrode material is marked as CS-8-2, and the charge capacity of the positive electrode material is 141.4 mAh/g.
Example 3
0.7L of core material solution and 0.3L of shell material solution are respectively taken and added into a reaction kettle in sequence, NaOH solution and ammonia water are added, and the pH value of the reaction kettle is adjusted to be about 11. The concentration of the NaOH solution is 10mol/L, the concentration of the ammonia water is 0.2mol/L, and the volume ratio of the NaOH solution to the ammonia water is 7: 3. Controlling the temperature of the solution to be about 50 ℃, stirring and introducing inert gas for protection. After the reaction liquid is completely added, the stirring speed is reduced, and the reaction liquid is aged for 24 hours. And after aging, filtering, washing and drying to obtain the precursor. 78g of Li were added in a molar ratio of Li to M1.05 to 1(M Ni, Co, Mn)2CO3As a lithium source, uniformly mixing, heating the mixed material to 750 ℃ in an oxygen atmosphere, preserving heat for 4h, and preserving heat for 12h at 820 ℃ to obtain the core-shell structure material Li [ (Ni)0.8Co0.1Mn0.1)0.7Co0.3]O2。
Mixing a certain amount of ethanol and deionized water, placing the mixture in a beaker, and weighing a certain amount of LiNbO3And Li2CO3Dissolving in the above solutionIn the solution, the molar ratio of Li to Nb is 1.02:1, and the solution is placed on a magnetic stirrer to be stirred for 15 min. Adding citric acid as chelating agent into the solution, stirring for 1 hr, and adding Li [ (Ni) as core-shell structure material0.8Co0.1Mn0.1)0.7Co0.3]O2And heating and stirring until a black gel is formed. Putting the black gel into a drying oven at 100 ℃ for drying for 2h, and then sintering the black gel in a muffle furnace at 800 ℃ in air atmosphere for 2h to volatilize organic matters in the material to obtain LiNbO3Coated Li [ (Ni)0.8Co0.1Mn0.1)0.7Co0.3]O2The positive electrode material is marked as CS-7-3, and the charge capacity of the positive electrode material is 140.3 mAh/g.
Comparative example 3
The positive electrode material of this comparative example was LiNi0.8Co0.1Mn0.1O2As a core material, LiNi0.8Co0.15Al0.15O2As shell material, with LiNbO3Is a coating layer.
Comparative example 4
The positive electrode material of this comparative example was LiNi0.8Co0.1Mn0.1O2As a core material, LiCoO2Is a shell material and is not coated. When preparing the positive plate, coating the surface of the positive material to form LiNbO3And (3) a layer.
Example 4
This example is substantially the same as example 1, except that the core-shell structure material and LiNbO are used3The mass ratio of (1) to (2) is 19:1, and the mass percentage of the coating layer is 5%.
Weighing a certain mass of positive electrode material, grinding and uniformly mixing the positive electrode material and sulfide electrolyte according to a certain mass ratio to obtain an ASS-LIB (all-solid lithium ion battery) positive electrode, pressing the sulfide with a certain mass as the electrolyte into a sheet, and adopting a Li-In alloy as a negative electrode. The battery is assembled according to the sequence of the anode, the electrolyte and the cathode, and is in a sandwich structure, and the operation process is carried out in a glove box. The ASS-LIB test conditions were: the cut-off voltage is 2.1-3.7V, the test temperature is 55 ℃ when the test sample is circulated for 50 weeks at a current density of 12 mA/g. And simultaneously, the prepared lithium ion battery is subjected to charge and discharge tests, constant current charge and discharge are carried out under the multiplying power of 0.1C, the lower limit voltage is 2.1V, and the upper limit voltage is 3.7V. The first charge-discharge diagram and the cycle performance diagram of the batteries prepared from the positive electrode materials of examples 1 to 3 and comparative examples 1 to 2 are shown in fig. 4 and 5, respectively, and the specific data of each example and comparative example are shown in table 1 below.
TABLE 1
In order to verify whether the core-shell structure of the cathode material is formed, EDS is adopted for characterization. In the section of the core-shell structure material, 10 points are selected along the radius from the center of the particle to the boundary of the particle, the content of the Ni, Co and Mn at the position is quantitatively analyzed and compared, the change trend of the element content is obtained, and thus whether the core-shell structure is formed or not is judged. Fig. 6 to 8 are EDS analysis diagrams of the cross sections of the core-shell structure materials prepared in examples 1 to 3, respectively, and the density of the selected test points depends on the thickness of the core and shell layers of the positive electrode material. The core material in the core-shell structure material is Li (Ni)0.8Co0.1Mn0.1)O2The shell material is LiCoO2Comparing fig. 6-8, it can be seen that the initial content of Ni element in the center of the material is higher than 80%, the content of Co and Mn element is slightly lower than 10%, and after a certain thickness of the core layer, the content of Ni, Co and Mn element is close to 8:1: 1; then, the content of Ni element is rapidly reduced, the content of Co element is also rapidly increased, and the content of Mn element has no obvious variation trend and is basically kept unchanged. Along with the increase of the grain diameter, the content of the Ni element has no obvious variation trend, the content of the Ni element and the Mn element is kept about 5 percent, and the content of the Co element is as high as about 90 percent. According to the variation trend of the contents of the three elements of Ni, Co and Mn, the core-shell structure of the core-shell structure material is divided into a core layer, a core-shell transition region and a shell layer, so that the core-shell structures of the anode materials with three different core-shell ratios are formed.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The positive electrode material is characterized in that the positive electrode material is a core-shell structure with a coating layer on the surface, the core-shell structure comprises a core and a shell layer coated on the surface of the core, the core is made of nickel-cobalt lithium manganate, the shell layer is made of lithium cobaltate, and the coating layer is made of lithium niobate and/or lithium titanate.
2. The positive electrode material as claimed in claim 1, wherein the molar ratio of the nickel-cobalt-manganese element in the core layer to the cobalt element in the shell layer is (1-x): x, 0.05 ≦ x ≦ 0.35.
3. The positive electrode material as claimed in claim 2, wherein the molar ratio of the nickel-cobalt-manganese element in the core layer to the cobalt element in the shell layer is (1-x): x, 0.05 ≦ x ≦ 0.15.
4. The positive electrode material according to claim 1, wherein the mass percentage of the coating layer is 1% to 5%.
5. The positive electrode material according to any one of claims 1 to 4, wherein the chemical formula of the lithium nickel cobalt manganese oxide is LiNi0.8Co0.1Mn0.1O2。
6. The preparation method of the cathode material is characterized by comprising the following steps of: mixing a core material solution, a shell material solution, alkali and a complexing agent to perform precursor reaction, then performing aging and solid-liquid separation to obtain a precursor, mixing the precursor with a first lithium source to perform sintering to obtain a core-shell structure material, mixing the core-shell structure material, a second lithium source, an organic solvent and a chelating agent, drying and sintering to obtain the anode material; the core material solution is a mixed salt solution of nickel salt, cobalt salt and manganese salt, the shell material solution is a cobalt salt solution, and the second lithium source is lithium niobate and/or lithium titanate.
7. The method according to claim 6, wherein the molar ratio of the nickel salt, the cobalt salt, and the manganese salt in the core material solution to the cobalt salt in the shell material solution is (1-x) x, 0.05 x 0.35.
8. The preparation method according to claim 6, wherein the mass ratio of the core-shell structure material to the second lithium source is (19-99): 1.
9. The method according to any one of claims 6 to 8, wherein the nickel salt is nickel sulfate, the cobalt salt is cobalt sulfate, and the manganese salt is manganese sulfate.
10. A battery comprising a negative electrode material and the positive electrode material according to any one of claims 1 to 5.
CN201911043836.9A 2019-10-30 2019-10-30 Positive electrode material, preparation method thereof and battery Pending CN110828797A (en)

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Cited By (5)

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CN113437273A (en) * 2021-06-28 2021-09-24 北京理工大学 All-solid-state lithium ion battery positive electrode material with coating layer on outer layer and preparation method thereof
CN113903909A (en) * 2021-10-11 2022-01-07 陕西红马科技有限公司 Cobalt nano coating modified nickel-rich low-cobalt single crystal multi-element positive electrode material and preparation method thereof
CN115133114A (en) * 2022-07-29 2022-09-30 重庆太蓝新能源有限公司 Solid electrolyte material, preparation method thereof and battery
WO2023045110A1 (en) * 2021-09-27 2023-03-30 中国科学院深圳先进技术研究院 Electrode cladding material screening method, electrode material and secondary battery
CN116387511A (en) * 2023-06-06 2023-07-04 江门市科恒实业股份有限公司 Positive electrode material, preparation method thereof and battery

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113437273A (en) * 2021-06-28 2021-09-24 北京理工大学 All-solid-state lithium ion battery positive electrode material with coating layer on outer layer and preparation method thereof
CN113437273B (en) * 2021-06-28 2022-10-11 北京理工大学 All-solid-state lithium ion battery positive electrode material with coating layer on outer layer and preparation method thereof
WO2023045110A1 (en) * 2021-09-27 2023-03-30 中国科学院深圳先进技术研究院 Electrode cladding material screening method, electrode material and secondary battery
CN113903909A (en) * 2021-10-11 2022-01-07 陕西红马科技有限公司 Cobalt nano coating modified nickel-rich low-cobalt single crystal multi-element positive electrode material and preparation method thereof
CN115133114A (en) * 2022-07-29 2022-09-30 重庆太蓝新能源有限公司 Solid electrolyte material, preparation method thereof and battery
CN116387511A (en) * 2023-06-06 2023-07-04 江门市科恒实业股份有限公司 Positive electrode material, preparation method thereof and battery
CN116387511B (en) * 2023-06-06 2023-08-18 江门市科恒实业股份有限公司 Positive electrode material, preparation method thereof and battery

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