阅读说明：本技术 一种锂离子正极材料表面包覆金属氧化物薄膜的方法 (Method for coating metal oxide film on surface of lithium ion anode material ) 是由 雷天起 陈龙 于 2019-08-22 设计创作，主要内容包括：本发明涉及一种锂离子正极材料表面包覆金属氧化物薄膜的方法,将锂离子正极材料在室温条件下恒湿处理5-20h,使锂离子正极材料表面自然吸附水蒸气至平衡；将金属化合物前驱体溶解于有机溶剂中；将恒湿处理过的锂离子正极材料粉体分散于所得的有机溶剂中,在惰性气体或氮气保护下,于50-70℃下进行化学液相沉积反应,金属化合物前驱体与锂离子正极材料表面的吸附水结合后定向水解,沉积在锂离子正极材料表面,有机溶剂受热挥发；待有机溶剂挥发完全后,将得到的粉体在烘箱中干燥,并在400-550<Sup>o</Sup>C焙烧3-5h,得到金属氧化物薄膜包覆的锂离子正极材料；所得材料表现出良好的充放电性能以及循环稳定性能,本发明方法工艺简单、环境友好,投入成本低,适合推广应用。(The invention relates to a method for coating a metal oxide film on the surface of a lithium ion anode material, which comprises the steps of carrying out constant-humidity treatment on the lithium ion anode material for 5-20h at room temperature to ensure that the surface of the lithium ion anode material naturally adsorbs water vapor to be balanced; dissolving a metal compound precursor in an organic solvent; dispersing the lithium ion cathode material powder treated by constant humidityCarrying out chemical liquid phase deposition reaction in the obtained organic solvent at 50-70 ℃ under the protection of inert gas or nitrogen, combining a metal compound precursor with adsorbed water on the surface of the lithium ion anode material, then directionally hydrolyzing, depositing on the surface of the lithium ion anode material, and heating and volatilizing the organic solvent; after the organic solvent is completely volatilized, drying the obtained powder in an oven, and drying the powder in a drying oven at 400-550 o C, roasting for 3-5h to obtain a lithium ion anode material coated by a metal oxide film; the obtained material has good charge and discharge performance and circulation stability, and the method has the advantages of simple process, environmental friendliness, low input cost and suitability for popularization and application.)

1. A method for coating a metal oxide film on the surface of a lithium ion anode material is characterized by comprising the following steps: the method comprises the following steps:

1) carrying out constant-humidity treatment on the lithium ion positive electrode material for 5-20h at room temperature, so that water vapor is naturally adsorbed on the surface of the lithium ion positive electrode material until the surface is balanced;

2) dissolving a metal compound precursor in an organic solvent;

3) dispersing the lithium ion anode material powder treated by the constant humidity in the step 1) into the organic solvent obtained in the step 2), carrying out chemical liquid phase deposition reaction at 50-70 ℃ under the protection of inert gas or nitrogen, combining a metal compound precursor with the absorbed water on the surface of the lithium ion anode material, then directionally hydrolyzing, depositing on the surface of the lithium ion anode material, and heating and volatilizing the organic solvent;

4) after the organic solvent is completely volatilized, drying the obtained powder in an oven, and drying the powder in a drying oven at 400-550^oAnd C, roasting for 3-5h to obtain the lithium ion anode material coated by the metal oxide film.

2. The method for coating the surface of the lithium ion cathode material with the metal oxide film according to claim 1, wherein the method comprises the following steps: the lithium ion positive electrode material is any one of the following materials:

Li(Ni_xCo_yMn_1-x-y)O₂wherein 0 is<x<1，0<y<1；

LiNi_xCo_1-xO₂Wherein x is more than or equal to 0 and less than or equal to 1;

Li(Ni_xCo_yAl_1-x-y)O₂wherein 0 is<x<1，0<y<1；

xLi₂MnO₃·(1-x)LiMO₂Wherein 0 is<x<1, M is at least one of Mn, Ni and Co;

LiNi_0.5Mn_1.5O₄。

3. the method for coating the surface of the lithium ion cathode material with the metal oxide film according to claim 1, wherein the method comprises the following steps: the metal compound precursor is selected from one of triethyl aluminum, diethyl aluminum chloride, tetrabutyl titanate, titanium tetrachloride, ethyl orthosilicate, silicon tetrachloride, tetrabutyl zirconate, zirconium isopropoxide and zirconium tetrachloride.

4. The method for coating the surface of the lithium ion cathode material with the metal oxide film according to claim 3, wherein the method comprises the following steps: the metal oxide film is one of aluminum oxide, titanium dioxide, silicon dioxide and zirconium dioxide.

5. The method for coating the surface of the lithium ion cathode material with the metal oxide film according to claim 1, wherein the method comprises the following steps: the organic solvent is selected from one or more of cyclohexane, n-hexane, decalin and olefin.

6. The method for coating the surface of the lithium ion cathode material with the metal oxide film according to claim 1, wherein the method comprises the following steps: the concentration of the metal compound precursor in the organic solvent in the step 2) is 2-15 g/L.

7. The method for coating the surface of the lithium ion cathode material with the metal oxide film according to claim 1, wherein the method comprises the following steps: the concentration of the lithium ion anode material powder in the organic solvent in the step 3) is 0.05-2.5 g/mL.

8. The method for coating the surface of the lithium ion cathode material with the metal oxide film according to claim 1, wherein the method comprises the following steps: and (4) increasing the thickness of the metal oxide film coated on the surface of the lithium ion cathode material by repeating the operations from the step 1) to the step 4).

Technical Field

The invention relates to the field of lithium ion anode materials, in particular to a method for coating a metal oxide film on the surface of a lithium ion anode material.

Background

With the rapid development of social economy, the problems of energy and environmental protection are increasingly prominent, and the problems become the main challenges faced by human at present; the development and utilization of renewable environment-friendly new energy are becoming more and more urgent, and a novel lithium ion battery belongs to clean energy, has the advantages of safety, high cyclicity, long service life, environmental friendliness and the like, and is regarded as one of the most effective electrochemical energy storage systems.

The energy density of lithium ion batteries mainly depends on the energy density of the cathode material, and the most widely used and studied cathode material at present is LiCoO₂、LiMn₂O₄、LiFePO₄(LFP) and the ternary material LiNi_xCo_yMn_zO₂(NCM) or LiNi_xCo_yAl_zO₂(NCA) and NMC materials are the current research hotspots due to high energy density, long service life and high safety performance.

The surface coating and modification are the most common means for improving the performance of the lithium ion battery anode material, and the effective coating can avoid the direct contact of an electrode active substance and electrolyte, inhibit the dissolution of transition metal, improve the mechanical strength of the anode material, and slow down the structure collapse phenomenon of the active material in the long-term charge and discharge process, thereby improving the electrochemical performance, the cycling stability and the rate capability of the material.

The coating method widely used at present generally utilizes a mode of fully mixing and then roasting the positive electrode material and a certain amount of solid particle substances, the method is not easy to achieve the uniform dispersion of coating substances on the surface of the positive electrode material, so that the optimal effect cannot be obtained with a smaller coating amount, and in addition, the mixing process (such as a ball milling method) and the high-temperature roasting process are easy to cause adverse effects such as the breakage of the positive electrode material particles, the structural damage and the like. Some novel methods such as Atomic Layer Deposition (ALD), Molecular Beam Epitaxy (MBE), Chemical Vapor Deposition (CVD), etc. can prepare a cathode material with a uniformly coated nanoscale thin film on the surface, but these methods are still limited to experimental level at present and are difficult to be applied in large scale, because the devices used in these methods are complex and expensive, and the process time is long, there are disadvantages such as low working efficiency, waste of resources, high cost, etc.

Disclosure of Invention

The invention aims to provide a method for coating a metal oxide film on the surface of a lithium ion positive electrode material, aiming at the defects of the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for coating a metal oxide film on the surface of a lithium ion anode material comprises the following steps:

1) carrying out constant-humidity treatment on the lithium ion positive electrode material for 5-20h at room temperature, so that water vapor is naturally adsorbed on the surface of the lithium ion positive electrode material until the surface is balanced;

2) dissolving a metal compound precursor in an organic solvent;

3) dispersing the lithium ion anode material powder treated by the constant humidity in the step 1) into the organic solvent obtained in the step 2), carrying out chemical liquid phase deposition reaction at 50-70 ℃ under the protection of inert gas or nitrogen, combining a metal compound precursor with the absorbed water on the surface of the lithium ion anode material, then directionally hydrolyzing, depositing on the surface of the lithium ion anode material, and heating and volatilizing the organic solvent;

4) and after the organic solvent is completely volatilized, drying the obtained powder in an oven, and roasting at the temperature of 400-550 ℃ for 3-5h to obtain the lithium ion cathode material coated by the metal oxide film.

In a further preferred embodiment, the lithium ion positive electrode material is any one of the following materials:

Li(Ni_xCo_yMn_1-x-y)O₂wherein 0 is<x<1，0<y<1；

LiNi_xCo_1-xO₂Wherein x is more than or equal to 0 and less than or equal to 1;

Li(Ni_xCo_yAl_1-x-y)O₂wherein 0 is<x<1，0<y<1；

xLi₂MnO₃·(1-x)LiMO₂Wherein 0 is<x<1, M is at least one of Mn, Ni and Co;

LiNi_0.5Mn_1.5O₄。

in a further preferred embodiment, the metal compound precursor is selected from one of triethyl aluminum, diethyl aluminum chloride, tetrabutyl titanate, titanium tetrachloride, ethyl orthosilicate, silicon tetrachloride, tetrabutyl zirconate, zirconium isopropoxide and zirconium tetrachloride.

In a further preferred embodiment, the metal oxide film is one of aluminum oxide, titanium dioxide, silicon dioxide and zirconium dioxide.

In a further preferred embodiment, the organic solvent is selected from one or more of cyclohexane, n-hexane, decalin and olefin.

Further preferably, the concentration of the metal compound precursor in the organic solvent in the step 2) is 2 to 15 g/L.

In a further preferable scheme, the concentration of the lithium ion cathode material powder in the organic solvent in the step 3) is 0.05-2.5 g/mL.

Further preferably, the thickness of the metal oxide film coated on the surface of the lithium ion cathode material is increased by repeating the operations from step 1) to step 4).

The invention has the beneficial effects that:

1. compared with the conventional mixing-roasting coating method, the method adopts a modified chemical liquid phase deposition method: through the constant humidity and deposition process, the metal compound precursor can be directionally hydrolyzed and deposited on the surface of the anode material to generate a more uniform metal oxide film, so that the contact between the anode material and the electrolyte is more effectively blocked, and the material structure is stabilized.

2. The method can accurately control the deposition amount and thickness of the oxide film on the surface of the lithium ion cathode material by adjusting the concentration of the metal compound precursor in the organic solvent and the times of repeating the operation steps according to different performance requirements.

3. Compared with the existing methods such as Atomic Layer Deposition (ALD), Molecular Beam Epitaxy (MBE), Chemical Vapor Deposition (CVD) and the like, the method provided by the invention is simple in process, environment-friendly, low in investment cost and suitable for popularization and application.

Drawings

FIG. 1 is a schematic view of a constant humidity apparatus used in an embodiment of the present invention;

FIG. 2 is a schematic view of a deposition apparatus used in an embodiment of the present invention;

wherein: 1-porcelain boat, 2-glass dryer, 3-heating stirrer, 4-water bath, 5-deposition flask, 6-protective gas inlet pipe, 7-condenser pipe and 8-organic solvent collection bottle.

Detailed Description

The invention will be further illustrated with reference to specific embodiments: