CN107394172B - Lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material and preparation method thereof - Google Patents

Lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material and preparation method thereof Download PDF

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CN107394172B
CN107394172B CN201710632461.4A CN201710632461A CN107394172B CN 107394172 B CN107394172 B CN 107394172B CN 201710632461 A CN201710632461 A CN 201710632461A CN 107394172 B CN107394172 B CN 107394172B
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lithium
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manganese
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李东林
孔祥泽
陈光琦
赵坤
赵珍珍
樊小勇
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Changan University
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    • 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
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Abstract

The invention particularly discloses a lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material which has a chemical general formula of (xLi)2MnO3·(1‑x)LiMO2)/yLi2WO4(ii) a Wherein x is more than or equal to 0.1 and less than or equal to 0.9, y is more than or equal to 0.001 and less than or equal to 0.4, and M is Mn, Co and Ni; the material comprises the following raw material components: manganese raw material, nickel raw material, cobalt raw material, lithium salt, tungsten salt, complexing agent, reducing agent and liquid solvent; and discloses a preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material. The invention utilizes the good conductivity of the lithium tungstate to greatly improve the rate capability of the anode material of the lithium ion battery, simultaneously improves the electrochemical stability of the anode material of the lithium ion battery, and obviously improves the cycle stability of the anode material of the lithium ion battery, so that the discharge platform and the capacity attenuation of the anode material of the lithium tungstate-coated lithium-rich manganese-based layered lithium ion battery are slowed down.

Description

Lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material and preparation method thereof
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material and a preparation method thereof.
Background
With the rapid development of economy and the continuous acceleration of industrialization process, the human demand for energy sources is increasing. Due to the over-development of resources such as coal and petroleum, the traditional energy sources are increasingly exhausted. In addition, a large amount of harmful gas and dust are generated in the combustion process of fossil fuel, and the environmental pollution is serious. And a great threat is brought to the environment on which human beings live. Therefore, the development of green energy sources capable of sustainable development is imperative.
The pollution-free sustainable green energy is expected to relieve environmental pollution, and new energy comprises wind energy, water energy, solar energy, geothermal energy and the like, but the functions of the energy are intermittent, and the energy needs to be stored by a device matched with the energy to be more reasonably utilized and released when the energy is needed. The secondary battery can realize the conversion of electric energy and chemical energy, and the rechargeable lithium ion battery is an important energy storage device in the past decade because the rechargeable lithium ion battery has good charge and discharge performance and good cycle performance, so the rechargeable lithium ion battery is a suitable energy storage device.
Currently, the lithium ion battery positive electrode material is mainly a lithium intercalation complex metal oxide, such as LiCoO2、LiMn2O4And LiFePO4And the like. However, LiCoO is caused by high cost, resource shortage and pollution2Cannot be applied on a large scale. And LiMn2O4And LiFePO4Has the advantages of low cost, rich content and certain competitiveness; however, LiMn2O4The specific discharge capacity of (A) is low, and 1C is about 120 mA/g. LiFePO4The energy density of (2) is low. Therefore, people always search for a new generation of electrode material with safety, environmental protection, high energy density and good cycle performance.
Through the continuous exploration of the prior anode material, the layered LiMnO is discovered2In the process of carrying out the doping modification, if the amounts of the metal element and the Li element are controlled, a composite oxide having a high energy density, which is called a lithium-rich cathode material, can be synthesized. The lithium-rich anode material has high reversible specific capacity, generally 200mAh/g-300mAh/g, better cycling stability and thermal stability and higher working voltage. LiCoO, which is considered to be currently commercialized2But its first cycle efficiency is low and rate performance and cycle stability are poor, limiting its commercialization. Thus, it is proposedThe high cycle stability of the anode materials is a problem to be solved urgently.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material and a preparation method thereof.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme.
The lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material is characterized in that the chemical general formula of the material is (xLi)2MnO3·(1-x)LiMO2)/yLi2WO4(ii) a Wherein x is more than or equal to 0.1 and less than or equal to 0.9, y is more than or equal to 0.001 and less than or equal to 0.4, and M is Mn, Co and Ni.
(II) the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is characterized by comprising the following raw material components: manganese raw material, nickel raw material, cobalt raw material, lithium salt, tungsten salt, complexing agent, reducing agent and liquid solvent.
Preferably, the manganese raw material is metal manganese, manganese oxide, manganese-containing inorganic salt, manganese-containing organic salt or manganese-containing alkoxide.
Further preferably, the manganese raw material is manganese nitrate, manganese sulfate, manganese formate, manganese acetate or manganese acetate.
Preferably, the nickel raw material is metallic nickel, nickel oxide, nickel-containing inorganic salt, nickel-containing organic salt or nickel-containing alkoxide.
Further preferably, the nickel raw material is nickel acetate, nickel nitrate, nickel sulfate, nickel formate or nickel acetate.
Preferably, the cobalt raw material is metallic cobalt, cobalt oxide, cobalt-containing inorganic salt, cobalt-containing organic salt or cobalt-containing alkoxide.
Further preferably, the cobalt raw material is cobalt acetate, cobalt nitrate, cobalt sulfate, cobalt formate or cobalt acetate.
Preferably, the lithium salt is lithium oxide, lithium-containing inorganic salt, lithium-containing organic salt, or lithium-containing alkoxide.
Further preferably, the lithium salt is lithium nitrate, lithium acetate, lithium formate, lithium hydroxide or lithium carbonate.
Preferably, the tungsten salt is a tungsten oxide, a tungsten-containing organic salt, a tungsten-containing inorganic salt, or a tungsten-containing alkoxide.
Further preferably, the tungsten salt is ammonium metatungstate, ammonium tungstate, tungsten pentachloride, or tungsten hexachloride.
Preferably, the complexing agent comprises an alcohol amine complexing agent, a hydroxycarboxylic acid complexing agent, an organic phosphate complexing agent or a polyacrylic acid complexing agent.
Further preferably, the complexing agent is citric acid, acetylacetone, ethylenediaminetetraacetic acid, sucrose, or glucose.
Preferably, the reducing agent comprises an inorganic acid reducing agent, an organic acid reducing agent or an alcohol reducing agent.
Further preferably, the reducing agent is citric acid.
Preferably, the liquid solvent is deionized water, ethylene glycol ethyl ether or ethanol.
Preferably, in the lithium salt, the manganese raw material, the nickel raw material and the cobalt raw material, when the manganese raw material is a divalent manganese raw material, the nickel raw material is a divalent nickel raw material and the cobalt raw material is a divalent cobalt raw material, Li+、Mn2+、Ni2+And Co2+The molar ratio of (1.1-1.9): (0.3997-0.9333): (0.2997-0.0333): (0.2997-0.0333).
Preferably, the chemical general formula of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material is (xLi)2MnO3·(1-x)LiMO2)/yLi2WO4Wherein M is manganese, cobalt and nickel; molar amount of the complexing agent to the (xLi)2MnO3·(1-x)LiMO2)/yLi2WO4The molar ratio of M is 1:1 to 2: 1.
(III) the preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is characterized by comprising the following steps:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: dissolving a manganese raw material, a nickel raw material, a cobalt raw material and a lithium salt in a liquid solvent in sequence, adding a complexing agent, heating in a water bath at 50-80 ℃, stirring and reacting for 3-5 hours to obtain a precursor sol, and then carrying out heat treatment on the precursor sol to obtain a lithium-rich manganese-based layered lithium ion battery anode material; wherein the heat treatment is performed according to the following operations: calcining for 3-5h at the temperature of 350-550 ℃ and then calcining for 12-24h at the temperature of 800-950 ℃ in a muffle furnace in an air atmosphere;
step 2, preparing a lithium tungstate precursor: dissolving a tungsten source and a reducing agent in a liquid solvent, heating the solution in a water bath at 50-70 ℃, stirring the solution for 2-3 hours, adding a lithium salt, and continuously stirring the solution for 1-2 hours to obtain a lithium tungstate sol;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: and mixing the lithium-manganese-rich-base layered lithium ion battery positive electrode material with the lithium tungstate sol, and sequentially stirring, ultrasonically permeating, carrying out negative pressure impregnation and carrying out heat treatment to obtain the lithium tungstate-modified lithium-manganese-rich-base layered lithium ion battery positive electrode material.
Preferably, in the step 3, the frequency of the ultrasonic wave is 40KHz, and the time of the ultrasonic penetration is 20-40 min.
Preferably, in step 3, the condition of the negative pressure impregnation is (-0.05) MPa- (-0.08) MPa.
Preferably, in step 3, the heat treatment is performed according to the following operations: calcining for 4-8h in a muffle furnace under the air atmosphere at the temperature of 600-750 ℃.
(IV) the preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is characterized by comprising the following steps of:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: dissolving a manganese raw material, a nickel raw material and a cobalt raw material in a liquid solvent in sequence, adding a complexing agent and a lithium salt, heating in a water bath at 50-70 ℃, stirring and reacting for 3-5 hours to obtain a precursor sol, and then carrying out heat treatment on the precursor sol to obtain a lithium-rich manganese-based layered lithium ion battery anode material; wherein the heat treatment is performed according to the following operations: calcining for 3-5h at the temperature of 350-550 ℃ and then calcining for 12-24h at the temperature of 800-950 ℃ in a muffle furnace in an air atmosphere;
step 2, preparing a lithium tungstate precursor: dissolving a tungsten source and a reducing agent in a liquid solvent, heating in a water bath at 50-70 ℃, stirring for 2-3h, adding a lithium salt, continuously stirring for 1-2h to form sol, and performing heat treatment to obtain a lithium tungstate precursor;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: and uniformly mixing the lithium-rich manganese-based layered lithium ion battery anode material with the lithium tungstate precursor, grinding, and then carrying out heat treatment to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material.
Preferably, in step 3, the grinding time is 2-5 h.
Preferably, in step 2 and step 3, the heat treatment is performed according to the following operations: calcining for 4-8h in a muffle furnace under the air atmosphere at the temperature of 600-750 ℃.
(V) the preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is characterized by comprising the following steps:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: firstly, dissolving a manganese raw material, a nickel raw material and a cobalt raw material in a liquid solvent in sequence to obtain a raw material mixed solution; then respectively dissolving sodium carbonate and sodium bicarbonate in a liquid solvent to respectively obtain a sodium carbonate solution and a sodium bicarbonate solution; dropwise adding the raw material mixed solution, a sodium carbonate solution and a sodium bicarbonate solution into deionized water at the same time, heating in a water bath at 50-70 ℃, stirring for reacting for 6-7h, and then sequentially aging, filtering and drying to obtain a carbonate precursor; then mixing the carbonate precursor with lithium salt, grinding, and finally carrying out heat treatment to obtain a lithium-rich manganese-based layered lithium ion battery anode material;
step 2, preparing a lithium tungstate precursor: dissolving a tungsten source and a reducing agent in a liquid solvent, heating in a water bath at 50-70 ℃, stirring for 2-3h, adding a lithium salt, continuously stirring for 1-2h to form sol, and performing heat treatment to obtain a lithium tungstate precursor;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: and uniformly mixing the lithium-rich manganese-based layered lithium ion battery anode material with the lithium tungstate precursor, grinding, and then carrying out heat treatment to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material.
Preferably, in step 1, the deionized water has a pH of 8 to 10.
Preferably, in step 1, the aging time is 10-12 h.
Preferably, in step 1, the heat treatment is performed according to the following operations: calcining for 12-24h in a muffle furnace under the air atmosphere at the temperature of 800-950 ℃.
Preferably, in step 3, the grinding time is 2-5 h.
Preferably, in step 2 and step 3, the heat treatment is performed according to the following operations: calcining for 4-8h in a muffle furnace under the air atmosphere at the temperature of 600-750 ℃.
(VI) the preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is characterized by comprising the following steps:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: firstly, dissolving a manganese raw material, a nickel raw material and a cobalt raw material in a liquid solvent in sequence to obtain a raw material mixed solution; then respectively dissolving sodium carbonate and sodium bicarbonate in a liquid solvent to respectively obtain a sodium carbonate solution and a sodium bicarbonate solution; dropwise adding the raw material mixed solution, a sodium carbonate solution and a sodium bicarbonate solution into deionized water at the same time, heating in a water bath at 50-70 ℃, stirring for reacting for 6-7h, and then sequentially aging, filtering and drying to obtain a carbonate precursor; then mixing the carbonate precursor with lithium salt, grinding, and finally carrying out heat treatment to obtain a lithium-rich manganese-based layered lithium ion battery anode material;
step 2, preparing a lithium tungstate precursor: dissolving a tungsten source and a reducing agent in a liquid solvent, heating the solution in a water bath at 50-70 ℃, stirring the solution for 2-3 hours, adding a lithium salt, and continuously stirring the solution for 1-2 hours to obtain a lithium tungstate sol;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: and mixing the lithium-manganese-rich-base layered lithium ion battery positive electrode material with the lithium tungstate sol, and sequentially stirring, ultrasonically permeating, carrying out negative pressure impregnation and carrying out heat treatment to obtain the lithium tungstate-modified lithium-manganese-rich-base layered lithium ion battery positive electrode material.
Preferably, in step 1, the deionized water has a pH of 8 to 10.
Preferably, in step 1, the aging time is 10-12 h.
Preferably, in step 1, the heat treatment is performed according to the following operations: calcining for 12-24h in a muffle furnace under the air atmosphere at the temperature of 800-950 ℃.
Preferably, in the step 3, the frequency of the ultrasonic wave is 40KHz, and the time of the ultrasonic penetration is 20-40 min.
Preferably, in step 3, the condition of the negative pressure impregnation is (-0.05) MPa- (-0.08) MPa.
Preferably, in step 3, the heat treatment is performed according to the following operations: calcining for 4-8h in a muffle furnace under the air atmosphere at the temperature of 600-750 ℃.
(VII) a preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material, which is characterized by comprising the following steps:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: dissolving a manganese raw material, a nickel raw material, a cobalt raw material and a lithium salt in a liquid solvent in sequence, adding a complexing agent, stirring for dissolving, performing hydrothermal reaction after dissolving, obtaining a solid precursor after the hydrothermal reaction is finished, and performing heat treatment on the solid precursor to obtain a lithium-rich manganese-based layered lithium ion battery anode material;
step 2, preparing a lithium tungstate precursor: dissolving a tungsten source and a reducing agent in a liquid solvent, heating in a water bath at 50-70 ℃, stirring for 2-3h, adding a lithium salt, and continuously stirring for 1-2h to form sol to obtain a lithium tungstate precursor;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: and mixing the lithium-rich manganese-based layered lithium ion battery positive electrode material with the lithium tungstate precursor, and sequentially carrying out stirring, ultrasonic infiltration, negative pressure impregnation and heat treatment to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery positive electrode material.
Preferably, in the step 1, the temperature of the hydrothermal reaction is 150-220 ℃, and the time of the hydrothermal reaction is 10-15 h.
Preferably, in step 1, the heat treatment is performed according to the following operations: calcining for 3-5h at the temperature of 350-550 ℃ and then calcining for 12-24h at the temperature of 800-950 ℃ in a muffle furnace in an air atmosphere.
Preferably, in the step 3, the frequency of the ultrasonic wave is 40KHz, and the time of the ultrasonic penetration is 20-40 min.
Preferably, in step 3, the condition of the negative pressure impregnation is (-0.05) MPa- (-0.08) MPa.
Preferably, in step 3, the heat treatment is performed according to the following operations: calcining for 4-8h in a muffle furnace under the air atmosphere at the temperature of 600-750 ℃.
(eight) a preparation method of a lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material, which is characterized by comprising the following steps:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: sequentially dissolving a manganese raw material, a nickel raw material, a cobalt raw material and a lithium salt in formaldehyde, adding resorcinol, stirring for dissolving, performing hydrothermal reaction after dissolving, obtaining a solid precursor after the hydrothermal reaction is finished, and performing heat treatment on the solid precursor to obtain a lithium-rich manganese-based layered lithium ion battery anode material; wherein the molar ratio of the resorcinol to the formaldehyde is 1: 2;
step 2, preparing a lithium tungstate precursor: dissolving a tungsten source and a reducing agent in a liquid solvent, heating in a water bath at 50-70 ℃, stirring for 2-3h, adding a lithium salt, continuously stirring for 1-2h to form sol, and performing heat treatment to obtain lithium tungstate precursor powder;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: and uniformly mixing the lithium-rich manganese-based layered lithium ion battery anode material with the lithium tungstate precursor powder, grinding, and then carrying out heat treatment to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material.
Preferably, in the step 1, the temperature of the hydrothermal reaction is 150-220 ℃, and the time of the hydrothermal reaction is 10-15 h.
Preferably, in step 1, step 2 and step 3, the heat treatment is performed according to the following operations: calcining for 4-8h in a muffle furnace under the air atmosphere at the temperature of 600-750 ℃.
Preferably, in step 3, the grinding time is 2-5 h.
Compared with the prior art, the invention has the beneficial effects that:
according to the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material provided by the invention, the rate capability of the lithium ion battery cathode material is greatly improved by utilizing the good conductivity of lithium tungstate, the electrochemical stability of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material is improved, the cycle stability of the lithium ion battery cathode material is obviously improved, and the discharge platform and the capacity attenuation of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material are slowed down.
Drawings
The invention is described in further detail below with reference to the figures and specific embodiments.
FIG. 1 is an X-ray diffraction (XRD) spectrum of a lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material of example 1; wherein a is a diffraction peak of lithium tungstate, b is a diffraction peak of the positive electrode material of the lithium-rich manganese-based layered lithium ion battery, and c is an X-ray diffraction spectrogram of the positive electrode material of the lithium-tungstate-modified lithium-rich manganese-based layered lithium ion battery; the abscissa is the measurement angle 2 θ of the X-ray diffraction in units, and the ordinate is the diffraction seal strength of the material at this diffraction angle in units of a.u.;
fig. 2 is a scanning electron microscope image of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material of example 4, with a magnification of 5 ten thousand times;
FIG. 3 is a comparison graph of the charge and discharge curves of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material and the unmodified lithium-rich manganese-based layered lithium ion battery cathode material of example 4 at a charge and discharge current density of 100 mA/g; in the figure, a is a charge-discharge curve of the unmodified lithium-rich manganese-based layered lithium ion battery anode material when the number of cycles is 1 st cycle; b is a charge-discharge curve of the unmodified lithium-rich manganese-based layered lithium ion battery anode material when the number of cycles is 200; c is a charge-discharge curve of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material when the number of cycles is 1 st cycle; d is a charge-discharge curve of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material when the number of cycles is 200; the abscissa is the specific capacity of the material, the unit is mAh/g, and the ordinate is the voltage, the unit is V;
FIG. 4 is a graph of the rate cycles of the lithium tungstate modified lithium-rich manganese-based layered positive electrode active material of example 1 at different discharge current densities; in the figure, a is a multiplying power cycle diagram of an unmodified lithium-rich manganese-based layered lithium ion battery anode material under different discharge current densities, and b is a multiplying power cycle diagram of a lithium tungstate modified lithium-rich manganese-based layered anode active material under different discharge current densities; the abscissa is the number of circulating turns, and the ordinate is the specific capacity of the material, and the unit is mAh/g;
FIG. 5 is a graph comparing the long cycle performance of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material prepared in example 1 with that of an unmodified lithium-rich manganese-based layered lithium ion battery cathode material; the abscissa is the number of cycles, and the ordinate is the specific capacity of the material, in mAh/g.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention.
Example 1
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) sequentially dissolving 0.067mol of manganese formate, 0.0167mol of cobalt formate, 0.0167mol of nickel formate and 0.15mol of lithium formate in 30mL of ethanol, adding 0.1mol of acetylacetone after full dissolution, stirring for 3 hours under the condition of 80 ℃ water bath to obtain precursor sol, and keeping the temperature in the air at 100 ℃ for 24 hours; then calcining in a muffle furnace, specifically calcining for 5h at 450 ℃,then calcining for 12h at 900 ℃ to obtain the powdery lithium-rich manganese-based layered lithium ion battery anode material, which has the chemical formula: 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2。
(2) Weighing 0.00046mol of citric acid, dissolving in 20mL of deionized water, adding 0.0000255mol of ammonium metatungstate, stirring for 2h under the condition of 70 ℃ water bath, adding 0.000611mol of lithium hydroxide, and continuing stirring for 2h to obtain the lithium tungstate sol.
(3) Weighing 1.6g of the lithium-rich manganese-based layered lithium ion battery anode material obtained in the step (1), immersing the anode material into a lithium tungstate sol, stirring, performing ultrasonic penetration for 20min at the ultrasonic frequency of 40KHz, performing negative pressure impregnation under the condition of-0.05 MPa, and drying to obtain a precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material; drying the obtained precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material in air at 70 ℃ for 24 hours, and finally calcining in a muffle furnace, specifically calcining at 650 ℃ for 5 hours to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material, which is powdery and has the chemical formula: (0.5 Li)2MnO3·0.5LiMn1/3Ni1/3Co1/3O2)/0.05Li2WO4。
Example 2
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) sequentially dissolving 0.333moL of manganese acetate, 0.083moL of cobalt nitrate, 0.083moL of nickel nitrate and 0.75moL of lithium nitrate in 20mL of deionized water, adding 0.5moL of citric acid, adjusting the pH value to 7 by using ammonia water, stirring for 5 hours under the condition of 50 ℃ water bath to form precursor sol, and preserving the temperature for 24 hours at 100 ℃ in the air; and then calcining in a muffle furnace, specifically: firstly calcining for 5 hours at the temperature of 450 ℃, and then calcining for 12 hours at the temperature of 900 ℃; obtaining the powdery lithium-rich manganese-based layered lithium ion battery anode material, which has the chemical formula: 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2。
(2) Weighing 0.0000573mol of citric acid, dissolving in 20mL of deionized water, adding 0.00000318mol of ammonium tungstate, stirring for 2h under the condition of 70 ℃ water bath, adding 0.000764mol of lithium nitrate, and continuing stirring for 2h to obtain the lithium tungstate sol.
(3) Weighing 10g of the lithium-manganese-rich layered lithium ion battery anode material prepared in the step (1), adding the lithium-manganese-rich layered lithium ion battery anode material into lithium tungstate sol, stirring, performing ultrasonic penetration for 20min at the ultrasonic frequency of 40KHz, performing negative pressure impregnation under the condition of-0.05 MPa, and drying to obtain a precursor of the lithium-manganese-rich layered lithium ion battery anode material modified by lithium tungstate; drying the precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material in air at 70 ℃ for 24 hours, and finally calcining in a muffle furnace, specifically calcining at 650 ℃ for 5 hours to obtain 0.91g of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material, which is powdery and has the chemical formula: (0.5 Li)2MnO3·0.5LiMn1/3Ni1/3Co1/3O2)/0.001Li2WO4。
Example 3
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) respectively weighing 1.2moL of lithium nitrate, 0.533moL of manganese sulfate, 0.133moL of nickel sulfate and 0.133moL of cobalt sulfate, dissolving in 30ml of ethylene glycol ethyl ether, adding 0.1moL of ethylene diamine tetraacetic acid for complexation after the lithium nitrate, the manganese sulfate and the cobalt sulfate are fully dissolved, stirring for 3h under the condition of 70 ℃ water bath to obtain precursor sol, and keeping the temperature in the air at 100 ℃ for 24 h; and then calcining in a muffle furnace, specifically calcining at 450 ℃ for 5h, and then calcining at 900 ℃ for 12h to obtain the lithium-rich manganese-based layered lithium ion battery anode material, wherein the chemical formula is as follows: 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2。
(2) Weighing 0.00138mol of citric acid, dissolving in 20mL of deionized water, adding 0.0000764mol of ammonium metatungstate, stirring for 2 hours at 70 ℃ in a water bath, adding 0.00183mol of lithium hydroxide, and continuing stirring for 1 hour to obtain the lithium tungstate sol.
(3) Weighing 12g of the lithium-rich manganese-based layered lithium ion battery anode material obtained in the step (1), and immersing the anode material into tungstenStirring the lithium tungstate sol, performing ultrasonic penetration for 20min at the ultrasonic frequency of 40KHz, performing negative pressure impregnation under the condition of-0.08 MPa, and drying to obtain a precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery positive material; drying the obtained precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material in air at 70 ℃ for 12 hours, and finally calcining in a muffle furnace, specifically calcining at 650 ℃ for 5 hours to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material, which is powdery and has the chemical formula: (0.5 Li)2MnO3·0.5LiMn1/3Ni1/3Co1/3O2)/0.02Li2WO4。
Example 4
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) respectively weighing 0.019moL of lithium nitrate, 0.00933moL of manganese nitrate, 0.00033moL of nickel nitrate and 0.00033moL of cobalt nitrate, dissolving in 30ml of deionized water, adding 0.1moL of glucose for complexation, stirring for 3h under the condition of 70 ℃ water bath to obtain precursor sol, and keeping the temperature in the air at 100 ℃ for 24-36 h; and then calcining in a muffle furnace, specifically calcining at 450 ℃ for 5h, and then calcining at 900 ℃ for 12h to obtain the lithium-rich manganese-based layered lithium ion battery anode material, which is powdery and has the chemical formula: 0.9Li2MnO3·0.1LiMn1/3Ni1/3Co1/3O2。
(2) Weighing 0.00161mol of citric acid, dissolving in 25mL of deionized water, adding 0.000178mol of tungsten hexachloride, stirring for 2h under the condition of 70 ℃ water bath, adding 0.00214mol of lithium hydroxide, continuously stirring for reaction for 1h to obtain lithium tungstate sol, and drying to obtain lithium tungstate precursor powder.
(3) Weighing 7g of the lithium-rich manganese-based layered lithium ion battery anode material prepared in the step (1), uniformly mixing with the lithium tungstate powder obtained in the step (2), grinding for 2 hours, and then carrying out heat treatment, wherein the method specifically comprises the following steps: calcining for 5 hours in a muffle furnace at the temperature of 650 ℃ to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material, wherein the chemical formula is as follows: (0.9 Li)2MnO3·0.1LiMn1/ 3Ni1/3Co1/3O2)/0.04Li2WO4。
Example 5
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) sequentially dissolving 0.00933moL manganese acetate, 0.00033moL cobalt acetate and 0.00033moL nickel acetate in 30mL deionized water, and stirring in a water bath at 50 ℃ to obtain a raw material mixed solution; dissolving 0.01moL of sodium carbonate in 40mL of deionized water to form a sodium carbonate aqueous solution; dissolving 0.01moL of ammonium bicarbonate in 40mL of deionized water to form an ammonium bicarbonate aqueous solution; three solutions of the raw material mixed solution, the sodium carbonate aqueous solution and the ammonium bicarbonate aqueous solution are subjected to three-phase parallel flow, and are simultaneously dropped into a deionized water solution with the pH of 9 at the same flow rate, the pH of the solution is controlled in the reaction process, the solution is stirred and reacts for 7 hours under the condition of a water bath at the temperature of 50 ℃, then the solution is precipitated for 12 hours, and then the solution is filtered and washed for 3 to 5 times by deionized water in a suction filtration mode, and then the solution is dried to remove water, so that a carbonate precursor is obtained; mixing the filtered powdery carbonate precursor with 1.9moL of lithium carbonate, grinding, and placing in a muffle furnace for heat treatment, specifically calcining at 900 ℃ for 15h to obtain a powdery lithium-rich manganese-based positive electrode material, wherein the chemical formula of the powdery lithium-rich manganese-based positive electrode material is as follows: 0.9Li2MnO3·0.1LiMn1/3Ni1/3Co1/3O2。
(2) Weighing 0.00275mol of citric acid, dissolving in 20mL of deionized water, adding 0.000306mol of tungsten pentachloride, stirring for 3h under the condition of 70 ℃ water bath, adding 0.00367mol of lithium hydroxide, and continuing to react for 2h to obtain the lithium tungstate sol.
(3) Weighing 1g of the lithium-manganese-rich layered lithium ion battery anode material obtained in the step (1), adding the lithium-manganese-rich layered lithium ion battery anode material into lithium tungstate sol, stirring, performing ultrasonic penetration for 40min at the ultrasonic frequency of 40KHz, performing negative pressure impregnation under the condition of-0.05 MPa, and drying to obtain a precursor of the lithium-manganese-rich layered lithium ion battery anode material modified by lithium tungstate; drying the obtained precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material in air at 70 ℃ for 12 hours, finally calcining in a muffle furnace, specifically calcining at 650 ℃ for 5 hours,and obtaining the powdery lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material. The chemical formula is: (0.9 Li)2MnO3·0.1LiMn1/3Ni1/3Co1/3O2)/0.4Li2WO4。
Example 6
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) sequentially dissolving 0.3267moL of manganese formate, 0.1867moL of formic acid cobalt and 0.1867moL of nickel formate in 50mL of deionized water, and stirring in a water bath at 50 ℃ to obtain a raw material mixed solution; dissolving 0.7moL of sodium carbonate in 40mL of deionized water to form a sodium carbonate aqueous solution; dissolving 0.7moL of ammonium bicarbonate in 40mL of deionized water to form an ammonium bicarbonate aqueous solution; three solutions of the raw material mixed solution, the sodium carbonate aqueous solution and the ammonium bicarbonate aqueous solution are subjected to three-phase parallel flow, the three solutions are simultaneously dropped into a deionized water solution with the pH value of 10 at the same flow rate of 5mL/h, the mixture is violently stirred for 7h under the condition of a water bath at the temperature of 50 ℃, then is precipitated for 12h, is washed for 3-5 times by deionized water in a suction filtration mode, and is dried to remove water to obtain a carbonate precursor; grinding the filtered powdery carbonate precursor and 0.84moL of lithium carbonate, placing the ground powdery carbonate precursor and 0.84moL of lithium carbonate into a muffle furnace for heat treatment, specifically calcining the ground powdery carbonate precursor and the lithium carbonate in the muffle furnace at 900 ℃ for 15 hours to obtain a powdery lithium-rich manganese-based positive electrode material, wherein the chemical formula is as follows: 0.2Li2MnO3·0.8LiMn1/3Ni1/3Co1/3O2。
(2) Weighing 0.00103mol of citric acid, dissolving in 20mL of deionized water, adding 0.0000573mol of ammonium tungstate, stirring for 2h under the condition of 70 ℃ water bath, adding 0.00138mol of lithium nitrate, continuously stirring for reaction for 1h to form sol, finally placing the sol in a muffle furnace, and calcining for 8h under the condition of 600 ℃ to obtain the powdery lithium tungstate precursor.
(3) Taking 6g of the lithium-rich manganese-based layered lithium ion battery anode material prepared in the step (1), uniformly mixing with the powdery ammonium tungstate precursor obtained in the step (2), grinding, calcining in a muffle furnace, specifically calcining at 650 ℃ for 5h to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material which is powdery,the chemical formula is: (0.2 Li)2MnO3·0.8LiMn1/3Ni1/3Co1/3O2)/0.03Li2WO4。
Example 7
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) sequentially dissolving 0.4moL of manganese acetate, 0.05moL of cobalt acetate and 0.05moL of nickel acetate in 90mL of deionized water, and stirring in a water bath at 50 ℃ to obtain a raw material mixed solution; dissolving 0.5moL of sodium carbonate in 30mL of deionized water to form a sodium carbonate aqueous solution; 0.5moL of ammonium bicarbonate is dissolved in 30mL of deionized water to form an ammonium bicarbonate aqueous solution; three phases of the three solutions are in parallel flow, the three solutions are simultaneously dropped into a deionized water solution with the pH value of 8 at the same flow rate, stirred for 7 hours in a water bath condition at the temperature of 50 ℃, precipitated for 12 hours, washed for 3-5 times by deionized water in a suction filtration mode, and dried to remove water to obtain a carbonate precursor; mixing the powdery carbonate precursor obtained by filtering with 0.85moL of lithium carbonate, and grinding for 2 hours; and finally, placing the anode material in a muffle furnace, and calcining the anode material for 15 hours at 900 ℃ to obtain a powdery lithium-rich manganese-based anode material, wherein the chemical formula is as follows: 0.7Li2MnO3·0.3LiMn1/3Ni1/ 3Co1/3O2。
(2) 0.00429moL of citric acid is weighed and dissolved in 20mL of deionized water, 0.0000238moL of ammonium metatungstate is added, stirring is carried out for 2 hours under the condition of 70 ℃ water bath, 0.00573moL of lithium hydroxide is added, and stirring reaction is carried out for 2 hours continuously to obtain the lithium tungstate sol.
(3) Adding 5g of the lithium-rich manganese-based layered lithium ion battery anode material in the step (1) into the lithium tungstate sol in the step (2), stirring, performing ultrasonic penetration for 30min at the ultrasonic frequency of 40KHz, performing negative pressure impregnation under the condition of-0.08 MPa, and drying to obtain a precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material; finally, drying the obtained precursor of the lithium tungstate modified rich lithium manganese base layered lithium ion battery anode material in air at 70 ℃ for 12-24h, calcining the precursor in a muffle furnace at 650 ℃ for 5h to obtain the powdery lithium tungstate modified rich lithium manganese base layered lithium ion battery anode material, and converting the powdery lithium tungstate modified rich lithium manganese base layered lithium ion battery anode material into a chemical formThe chemical formula is: (0.7 Li)2MnO3·0.3LiMn1/3Ni1/3Co1/3O2)/0.15Li2WO4。
Example 8
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) sequentially dissolving 0.04moL of manganese nitrate, 0.024moL of cobalt nitrate, 0.024moL of nickel nitrate and 0.104moL of lithium nitrate in formaldehyde, then adding resorcinol, and stirring for dissolving; wherein, the addition amount of the resorcinol is as follows: n (formaldehyde) is 1: 2; transferring the mixture to a polytetrafluoroethylene lining hydrothermal reaction kettle after the mixture is completely dissolved, then carrying out hydrothermal reaction for 12 hours at the reaction temperature of 180 ℃, obtaining a solid precursor after the reaction is finished, and calcining the solid precursor for 12 hours at the temperature of 850 ℃ to obtain a powdery lithium-rich manganese-based positive electrode material, wherein the chemical formula is as follows: 0.1Li2MnO3·0.9LiMn1/3Ni1/3Co1/3O2。
(2) 0.0309moL of citric acid and 0.000172moL of ammonium tungstate are weighed and dissolved in 20mL of deionized water, the mixture is stirred for 2 hours under the condition of 70 ℃ water bath, 0.0413moL of lithium hydroxide is added, and the reaction is continued for 1 hour to obtain the lithium tungstate sol.
(3) Adding 3g of the lithium-rich manganese-based layered lithium ion battery anode material in the step (1) into lithium tungstate sol, stirring, performing ultrasonic penetration for 20min at the ultrasonic frequency of 40KHz, performing negative pressure impregnation under the condition of-0.05 MPa, and drying to obtain a precursor of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material; and then drying the obtained precursor of the lithium tungstate modified rich lithium manganese base layered lithium ion battery anode material in air at 70 ℃ for 12-24h, and finally calcining the precursor in a muffle furnace at 650 ℃ for 5h to obtain the powdery lithium tungstate modified rich lithium manganese base layered lithium ion battery anode material. The chemical formula is: (0.1 Li)2MnO3·0.9LiMn1/3Ni1/3Co1/3O2)/0.18Li2WO4。
Example 9
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) sequentially dissolving 0.032moL of manganese sulfate, 0.018moL of cobalt sulfate, 0.018moL of nickel sulfate and 0.078moL of lithium acetate in formaldehyde according to the stoichiometric ratio, adding resorcinol, and stirring for dissolving; wherein, the addition amount of the resorcinol is as follows: n (formaldehyde) is 1: 2; transferring the mixture to a lining hydrothermal reaction kettle made of polytetrafluoroethylene after complete dissolution, then carrying out hydrothermal reaction for 15 hours at the reaction temperature of 150 ℃, obtaining a solid precursor after the reaction is finished, placing the solid precursor in a muffle furnace, and calcining for 12 hours at 850 ℃ to obtain a powdery lithium-rich manganese-based positive electrode material, wherein the chemical formula is as follows: 0.1Li2MnO3·0.9LiMn1/3Ni1/3Co1/3O2。
(2) 0.00143moL of citric acid is weighed and dissolved in 20mL of deionized water, 0.0000769moL of ammonium tungstate is added, stirring is carried out for 2 hours under the condition of 60 ℃ water bath, 0.00191moL of lithium nitrate is added, sol is formed by stirring, and lithium tungstate precursor powder is obtained by heat treatment.
(3) Taking 5g of the lithium-rich manganese-based layered lithium ion battery anode material in the step (1) and the ammonium tungstate precursor obtained in the step (2) to be uniformly mixed, grinding for 3 hours, placing in a muffle furnace, and calcining for 5 hours at 650 ℃ to obtain the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material, wherein the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is powdery and has the chemical formula: (0.1 Li)2MnO3·0.9LiMn1/3Ni1/3Co1/3O2)/0.05Li2WO4。
Example 10
A lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material comprises the following steps:
(1) respectively weighing 0.019moL of lithium nitrate, 0.00933moL of manganese nitrate, 0.00033moL of nickel nitrate and 0.00033moL of cobalt nitrate, dissolving in 30ml of deionized water, adding 0.1moL of sucrose for complexing, stirring for 5 hours under the condition of 80 ℃ water bath, preserving heat for 36 hours at 100 ℃ in air, then placing in a muffle furnace, firstly calcining for 5 hours at 450 ℃, and then calcining for 12 hours at 900 ℃; obtaining a powdery lithium-rich manganese-based layerThe lithium ion battery anode material has a chemical formula as follows: 0.9Li2MnO3·0.1LiMn1/3Ni1/ 3Co1/3O2。
(2) Weighing 0.0023mol of citric acid and 0.000255mol of tungsten hexachloride, dissolving in 20mL of deionized water, stirring for 3h under the condition of 70 ℃ water bath, adding 0.00306mol of lithium nitrate, continuously stirring for reaction for 1h to form sol, and performing heat treatment to obtain a powdery lithium tungstate precursor.
(3) Uniformly mixing 2g of the lithium-rich manganese-based layered lithium ion battery anode material in the step (1) with the powdery lithium tungstate precursor obtained in the step (2), and grinding for 5 hours; and finally, calcining the lithium tungstate-modified lithium-rich manganese-based layered lithium ion battery anode material for 4 hours in a muffle furnace at the temperature of 750 ℃ to obtain the lithium tungstate-modified lithium-rich manganese-based layered lithium ion battery anode material, wherein the chemical formula is as follows: (0.9 Li)2MnO3·0.1LiMn1/3Ni1/3Co1/3O2)/0.2Li2WO4。
The lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material prepared in the above embodiments is subjected to electrochemical performance detection, and the detection results are as follows:
fig. 1 is an X-ray diffraction (XRD) spectrum of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material prepared in example 1. The figure marks a diffraction peak corresponding to lithium tungstate and a diffraction peak of the lithium-rich manganese-based layered lithium ion cathode material as a raw material. After the diffraction peak marked with the position of the lithium tungstate in the figure is compared with a standard card of the lithium tungstate, the diffraction peak of the material synthesized by the method has sharp diffraction peaks on corresponding crystal faces and is consistent with the diffraction peak of the standard card of the lithium tungstate. The method synthesizes pure-phase lithium tungstate without impurities, and the target substance is synthesized by the method and has high purity. In addition, the diffraction peak position of the labeled raw material lithium-rich manganese-based layered lithium ion positive electrode material is compared with a pure sample unmodified positive electrode material, and the result of the test of the modified material is similar to that of the unmodified positive electrode material, so that the original three-party layered structure is maintained, and the diffraction peak corresponding to the lithium tungstate material is also generated except for the diffraction peak of the original lithium-rich manganese-based layered lithium ion positive electrode material in the whole map. The conclusion can be drawn that the structure of the lithium tungstate modified lithium-rich manganese-based layered lithium ion anode material is synthesized, the layered structure of the original anode material is not changed, a new lithium tungstate phase appears in the composite material, and the inherent performance of the raw material is maintained.
The XRD detection results of other examples are the same as the detection results of example 1, which all show that the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery positive electrode material does not change the inherent structure of the lithium-rich manganese-based layered lithium ion battery positive electrode material, and maintains its inherent properties.
Fig. 2 is a scanning electron microscope image of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material prepared in example 4, and the image is an image of the modified material at 5 ten thousand times magnification. It can be seen from the figure that the particle size of the lithium tungstate modified lithium-rich manganese-based layered cathode active material prepared in example 5 is different from 200-400nm, the particle size is slightly increased after modification, and the modified lithium tungstate modified lithium-rich manganese-based layered cathode active material has obvious agglomeration phenomenon and no obvious edge angle. This is probably because lithium tungstate is modified on the surface of the lithium-rich manganese-based layered positive electrode active material.
The characterization results of the scanning electron microscope in other examples are consistent with the results of example 5, and all the results show that the lithium tungstate is well modified on the lithium-rich manganese-based layered lithium ion battery cathode material.
Fig. 3 is a comparative graph of the charge and discharge curves of the 1 st and 200 th cycles of the lithium tungstate modified lithium-rich manganese-based layered cathode active material prepared in example 4 and the unmodified lithium-rich manganese-based layered cathode active material at a charge and discharge current density of 100 mA/g. In the graph, the upward curves represent the cyclic charge data, and the downward curves represent the cyclic discharge data. As can be seen from the figure, the charging curves of the lithium tungstate modified lithium-rich manganese-based layered positive electrode active material and the unmodified lithium-rich manganese-based layered positive electrode active material are basically consistent, and both consist of two parts which are obvious, wherein one part is LiMn starting from 3.7V1/3Ni1/3Co1/3O2Another part is Li at 4.5V2MnO3A long platform. Two kinds of curves are shown inThe charging and discharging curves of the 1 st circle are very close, the first discharging platform of the lithium tungstate modified lithium-rich manganese-based layered positive active material is slightly improved, the discharging platform is slowly decayed along with the charging and discharging, and the platform is smooth and square; meanwhile, the specific discharge capacity of the material is slightly improved. The first discharge specific capacity of the unmodified lithium-rich manganese-based layered positive electrode active material is 251mAh/g, and the capacity of the lithium tungstate modified lithium-rich manganese-based layered positive electrode active material is 258 mAh/g; along with the circulation, at the 200 th circle, the capacity attenuation of the unmodified lithium-rich manganese-based layered positive electrode active material is serious, namely, the capacity attenuation is from 251mAh/g to 108mAh/g, the capacity attenuation rate is 56.97%, and the inflection point of a discharge platform is attenuated from 3.4V to 2.5V; the discharge specific capacity of the lithium tungstate modified lithium-rich manganese-based layered positive electrode active material is still 140mAh/g, the capacity decay rate is 42.63%, and the platform inflection point is reduced from 3.5V to 3.0V; the improved plateau and capacity improvement is more pronounced compared to the first ring. The detection result also shows that compared with the unmodified lithium-rich manganese-based layered positive active material, the effect of the lithium tungstate modified lithium-rich manganese-based layered positive active material on the discharge specific capacity and the platform attenuation is improved more remarkably after the number of cycles is more than 200. Therefore, the discharge platform and the discharge specific capacity attenuation of the lithium-rich manganese-based layered lithium ion battery anode material can be effectively improved after the lithium tungstate is modified.
The charge and discharge performance test results of other examples are equivalent to the results of example 4, the discharge specific capacity is basically maintained at about 150mAh/g at 200 circles, and the discharge platform and the discharge specific capacity are slowly attenuated.
Fig. 4 is a multiplying power cycle diagram of the lithium tungstate modified lithium-rich manganese-based layered cathode active material prepared in example 1 under different discharge current densities. As can be seen from the figure, in the circulation process of the current density of 20mA/g, the capacity of the unmodified lithium-rich manganese-based layered lithium ion battery anode material is attenuated quickly, and the capacity attenuation of the modified lithium tungstate is obviously improved. The whole circulation diagram shows that the modified lithium tungstate is beneficial to improving the discharge specific capacity of the material, and the improvement is more obvious under the condition of high current density. The specific capacity of the unmodified lithium-rich manganese-based layered positive active material under the discharge current density of 400mA/g is 22.1mAh/g, and the specific discharge capacity of the lithium tungstate modified lithium-rich manganese-based layered positive active material under the current density of 1000mA/g is still 63.4 mAh/g. It was therefore concluded that: the multiplying power of the lithium tungstate modified lithium-rich manganese-based layered positive electrode active material is obviously improved, and the improvement under the high current density is especially obvious.
The rate cycle test results of other embodiments are equivalent to the test results of embodiment 1, and the characteristics of improved discharge specific capacity, gradual attenuation of a discharge platform and high rate are also shown.
Fig. 5 is a graph comparing long cycle performance of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material prepared in example 1 and an unmodified lithium-rich manganese-based layered lithium ion battery cathode material. As can be seen from the figure, the cycle performance of the lithium ion battery anode material modified by the lithium tungstate is greatly improved, and the capacity decay speed is reduced in the later period; when the number of the circulating circles is 100, the specific capacity can be kept at 175mAh/g, and the specific capacity of the unmodified lithium ion battery anode material is attenuated to 148 mAh/g.
The long-cycle performance test results of other examples are basically equivalent to the results of example 1, and the specific capacity is kept above 160mAh/g when the number of cycles is 100.
According to the invention, the capacity, platform attenuation and rate capability of the anode material of the lithium-rich manganese-based layered lithium ion battery are improved by utilizing the good conductivity of the lithium tungstate, and the electrode material with slow attenuation of platform and discharge specific capacity and high rate is obtained.
Although the present invention has been described in detail in this specification with reference to specific embodiments and illustrative embodiments, it will be apparent to those skilled in the art that modifications and improvements can be made thereto based on the present invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims (2)

1. The preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery cathode material is characterized in that the lithium tungstate modified lithium-rich manganese-based layered lithium ionThe chemical general formula of the battery anode material is (xLi)2MnO3·(1-x)LiMO2)/yLi2WO4(ii) a Wherein x is more than or equal to 0.1 and less than or equal to 0.9, y is more than or equal to 0.001 and less than or equal to 0.4, and M is Mn, Co and Ni; the material comprises the following raw material components: manganese raw material, nickel raw material, cobalt raw material, lithium salt, tungsten salt, complexing agent, reducing agent and liquid solvent; among the lithium salt, the manganese raw material, the nickel raw material and the cobalt raw material, when the manganese raw material is a divalent manganese raw material, the nickel raw material is a divalent nickel raw material and the cobalt raw material is a divalent cobalt raw material, wherein Li+、Mn2 +、Ni2+And Co2+The molar ratio of (1.1-1.9) to (0.3997-0.9333) to (0.2997-0.0333) to (0.2997-0.0333); the complexing agent is citric acid, acetylacetone, ethylene diamine tetraacetic acid, sucrose or glucose, and the molar weight of the complexing agent is equal to that of the (xLi)2MnO3·(1-x)LiMO2)/yLi2WO4The molar weight ratio of M is 1:1 to 2: 1;
the preparation method comprises the following steps:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: dissolving a manganese raw material, a nickel raw material, a cobalt raw material and a lithium salt in a liquid solvent in sequence, adding a complexing agent, heating in a water bath at 50-80 ℃, stirring and reacting for 3-5 hours to obtain a precursor sol, and then carrying out heat treatment on the precursor sol to obtain a lithium-rich manganese-based layered lithium ion battery anode material; wherein the heat treatment is performed according to the following operations: calcining for 3-5h at the temperature of 350-550 ℃ and then calcining for 12-24h at the temperature of 800-950 ℃ in a muffle furnace in an air atmosphere;
step 2, preparing a lithium tungstate precursor: dissolving tungsten salt and a reducing agent in a liquid solvent, heating in a water bath at 50-70 ℃, stirring for 2-3h, adding a lithium salt, and continuously stirring for 1-2h to obtain a lithium tungstate sol; the reducing agent is citric acid;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: mixing the lithium-manganese-rich-base layered lithium ion battery positive electrode material with the lithium tungstate sol, and sequentially carrying out stirring, ultrasonic infiltration, negative pressure impregnation and heat treatment to obtain a lithium tungstate-modified lithium-manganese-rich-base layered lithium ion battery positive electrode material; wherein the frequency of the ultrasonic wave for ultrasonic penetration is 40KHz, and the time for ultrasonic penetration is 20-40 min; the heat treatment is carried out according to the following operations: calcining for 4-8h in a muffle furnace at the temperature of 600-750 ℃ in the air atmosphere; the negative pressure impregnation condition is (-0.05) MPa- (-0.08) MPa.
2. The preparation method of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is characterized in that the chemical general formula of the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material is (xLi)2MnO3·(1-x)LiMO2)/yLi2WO4(ii) a Wherein x is more than or equal to 0.1 and less than or equal to 0.9, y is more than or equal to 0.001 and less than or equal to 0.4, and M is Mn, Co and Ni; the material comprises the following raw material components: manganese raw material, nickel raw material, cobalt raw material, lithium salt, tungsten salt, complexing agent, reducing agent and liquid solvent; among the lithium salt, the manganese raw material, the nickel raw material and the cobalt raw material, when the manganese raw material is a divalent manganese raw material, the nickel raw material is a divalent nickel raw material and the cobalt raw material is a divalent cobalt raw material, wherein Li+、Mn2 +、Ni2+And Co2+The molar ratio of (1.1-1.9) to (0.3997-0.9333) to (0.2997-0.0333) to (0.2997-0.0333); the complexing agent is citric acid, acetylacetone, ethylene diamine tetraacetic acid, sucrose or glucose, and the molar weight of the complexing agent is equal to that of the (xLi)2MnO3·(1-x)LiMO2)/yLi2WO4The molar weight ratio of M is 1:1 to 2: 1;
the preparation method comprises the following steps:
step 1, preparing a lithium-rich manganese-based layered lithium ion battery anode material: dissolving a manganese raw material, a nickel raw material, a cobalt raw material and a lithium salt in a liquid solvent in sequence, adding a complexing agent, stirring for dissolving, performing hydrothermal reaction after dissolving, obtaining a solid precursor after the hydrothermal reaction is finished, and performing heat treatment on the solid precursor to obtain a lithium-rich manganese-based layered lithium ion battery anode material; wherein, in the step 1, the temperature of the hydrothermal reaction is 150-220 ℃, and the time of the hydrothermal reaction is 10-15 h; the heat treatment is carried out according to the following operations: calcining for 3-5h at the temperature of 350-550 ℃ and then calcining for 12-24h at the temperature of 800-950 ℃ in a muffle furnace in an air atmosphere;
step 2, preparing a lithium tungstate precursor: dissolving tungsten salt and a reducing agent in a liquid solvent, heating in a water bath at 50-70 ℃, stirring for 2-3h, adding a lithium salt, and continuously stirring for 1-2h to form sol to obtain a lithium tungstate precursor; the reducing agent is citric acid;
step 3, preparing the lithium tungstate modified lithium-rich manganese-based layered lithium ion battery anode material: mixing the lithium-rich manganese-based layered lithium ion battery positive electrode material with the lithium tungstate precursor, and sequentially carrying out stirring, ultrasonic infiltration, negative pressure impregnation and heat treatment to obtain a lithium tungstate modified lithium-rich manganese-based layered lithium ion battery positive electrode material; in the step 3, the frequency of the ultrasonic wave is 40KHz and the time of the ultrasonic penetration is 20-40min during the ultrasonic penetration; the negative pressure impregnation condition is (-0.05) MPa- (-0.08) MPa; the heat treatment is carried out according to the following operations: calcining for 4-8h in a muffle furnace under the air atmosphere at the temperature of 600-750 ℃.
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