WO2015027692A1

WO2015027692A1 - Composite negative electrode material of lithium-ion battery, preparation method therefor, and lithium-ion battery

Info

Publication number: WO2015027692A1
Application number: PCT/CN2014/072417
Authority: WO
Inventors: 张光辉
Original assignee: 华为技术有限公司
Priority date: 2013-08-26
Filing date: 2014-02-22
Publication date: 2015-03-05
Also published as: CN104425808A; CN104425808B

Abstract

An embodiment of the present invention provides a composite negative electrode material of a lithium-ion battery. The compound negative electrode material of the lithium-ion battery comprises a transition metal oxide and a cladding layer cladding the surface of the transition metal oxide. The transition metal oxide comprises one or more of NiO, Fe₂O₃, Fe₃O₄, TiO₂, CuO and Co₃O₄. The cladding layer material comprises Li₄Ti₅O₁₂. The composite negative electrode material of the lithium-ion battery has high capacity and has good cycling stability and durability. An embodiment of the present invention also provides a method for preparing the composite negative electrode material of the lithium-ion battery, and the lithium-ion battery comprising the composite negative electrode material of the lithium-ion battery.

Description

Lithium ion battery composite anode material, preparation method thereof and lithium ion battery The application No. 201310375542.2 submitted to the Chinese Patent Office on August 26, 2013, the invention name is "a lithium ion battery composite anode The material and its preparation method and the priority of the Chinese patent application of the lithium ion battery are hereby incorporated by reference in its entirety. Technical field

The present invention relates to the field of lithium ion batteries, and in particular to a lithium ion battery composite anode material, a preparation method thereof and a lithium ion battery. Background technique

Since the 1990s, among many energy substitutes, lithium-ion batteries have attracted close attention due to their high energy density, good cycle performance, and no memory effect. With the development of low-carbon economy, lithium-ion batteries are actively developing in the direction of power vehicles and grid energy storage. Therefore, the development of lithium-ion batteries with high energy density and long cycle life has become the focus of research in the industry.

At present, most commercial lithium-ion batteries use carbon-based materials as negative electrodes, but carbon-based anode materials have many defects. For example, the first charge and discharge forms a solid electrolyte interface film (SEI), causing irreversible capacity loss, insufficient cycle performance, and high temperature failure risk. And security risks, etc., these problems make carbon-based materials have been unable to meet the needs of energy storage batteries. Some lithium-ion batteries use alloy materials as the anode material. Although the alloy materials have a high specific capacity, the alloy materials have large volume expansion and poor cycle performance, which cannot meet the needs of market applications.

In addition, metal oxides (NiO, Fe ₂ O ₃ , Fe ₃ 0 ₄ , Ti0 ₂ , CuO and Co ₃ 0 ₄ ) are also studied. Many lithium ion battery anode materials, these materials have high lithium insertion capacity (>600mAh/g), and the lithium insertion potential is close to that of lithium titanate. However, these materials have high irreversible capacity for the first time, and the charging and discharging platform is unstable and the cycle performance is poor. In the process of charge and discharge, the metal oxide material agglomerates to reduce its cycle performance, and the metal oxide material reacts with the electrolyte to decompose, resulting in a decrease in reversible capacity and failing to meet the long cycle performance requirements of the energy storage battery. The use of metal oxide materials in lithium ion batteries is limited. Summary of the invention

In view of this, the first aspect of the embodiments of the present invention provides a lithium ion battery composite anode material, which solves the problem that the metal oxide anode material is easy to agglomerate and easily decomposes with the electrolyte, thereby causing the battery to have low durability and The problem of poor cycle performance.

In a first aspect, an embodiment of the present invention provides a lithium ion battery composite anode material, comprising a transition metal oxide, and a coating layer coated on the surface of the transition metal oxide, the transition metal oxide including NiO One or more of Fe ₂ O ₃ , Fe ₃ 0 ₄ , Ti0 ₂ , CuO and Co ₃ 0 ₄ , and the material of the coating layer includes Li ₄ Ti ₅ 0 ₁₂ .

Preferably, the coating layer has a thickness of 50 to 8000 nm. More preferably, the coating layer has a thickness of from 1000 to 4000 nm.

Preferably, the transition metal oxide accounts for 10% to 95% of the total mass of the lithium ion battery composite anode material.

More preferably, the transition metal oxide accounts for 60% to 80% of the total mass of the lithium ion battery composite negative electrode material.

Since Li ₄ Ti ₅ 0 ₁₂ has low electron conductance and ion conductivity, in order to improve the electrical conductivity of the lithium ion battery composite anode material, the material of the coating layer may further include a conductive addition agent. The conductive additive is one or more of artificial graphite, natural graphite, acetylene black, carbon black, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, phenolic resin, and sucrose. The conductive additive accounts for 1% to 5% of the total mass of the lithium ion battery composite anode material.

A lithium ion battery composite anode material provided by the first aspect of the present invention includes a transition metal oxide and a coating layer coated on the surface of the transition metal oxide, wherein the transition metal oxide is selected from the group consisting of NiO (oxidation) One or more of nickel), Fe ₂ 0 ₃ (iron oxide), Fe ₃ 0 ₄ (triiron tetroxide), Ti0 ₂ (titanium oxide), CuO (copper oxide), and Co ₃ 0 ₄ (cobalt oxide) Kind. These transition metal oxides have a high lithium insertion capacity (>600 mAh/g), which enables the lithium ion battery composite anode material to have a higher capacity; the cladding material includes Li ₄ Ti ₅ 0 ₁₂ , which has the following Large advantages: (1) 1^ ₄ 13⁄40 ₁₂ is a "zero strain" electrode material. During lithium ion intercalation-deintercalation, the volume change is small and the structure is stable, so it has excellent cycle performance; (2) ₄ 13⁄40 ₁₂ It has a three-dimensional lithium ion channel, and its lithium ion diffusion coefficient is one order of magnitude larger than that of the carbon-based anode material, which can improve the rate performance of the lithium battery; (3) Li ₄ Ti ₅ 0 _{12 has} an equilibrium potential of about 1.55 V, which can effectively prevent lithium metal deposition. Improve the safety performance of the lithium ion battery. At the same time, due to the high lithium insertion potential, the SEI film formation potential is not reached. The electrolyte does not undergo reductive decomposition on the surface of Li ₄ Ti ₅ 0 ₁₂ , which is beneficial to maintain the stability of the electrolyte and improve the cycle performance. ; Accordingly, the present invention will be Li ₄ Ti ₅ 0 ₁₂ coated on the surface of a transition metal oxide, transition metal oxide surface capable of covering the active sites, so as to effectively protect the transition metal oxide To prevent the transition metal oxide with the electrolyte decomposition reaction, the transition metal oxide to prevent agglomeration, the lithium ion battery while the composite negative electrode material having a high capacity, good cycle stability and durability. In addition, since 1^ ₄ 13⁄40 ₁₂ has a three-dimensional lithium ion channel, its lithium ion diffusion coefficient is large, so that the rate performance of the lithium ion battery can be improved. Moreover, the lithium insertion potential of these transition metal oxide materials is close to that of Li ₄ Ti ₅ 0 ₁₂ , so that the lithium ion battery composite anode material can have a smooth and uniform charge and discharge platform.

In a second aspect, an embodiment of the present invention provides a method for preparing a lithium ion battery composite anode material. The method includes the following steps:

(1) mixing the raw material lithium source, the titanium source and the transition metal oxide to be coated in a dispersion medium to uniformly disperse and form a slurry;

The coating raw material lithium source is selected from one or more selected from the group consisting of lithium hydroxide, lithium hydroxide hydrate, lithium carbonate, lithium nitrate, lithium sulfate, lithium fluoride, lithium oxalate, lithium chloride and lithium acetate;

The coated raw material titanium source is selected from one or more of titanium dioxide, titanium tetrachloride, titanium trichloride, titanium isopropoxide, tetrabutyl titanate, butyl titanate and n-propyl titanate;

The transition metal oxide is selected from one or more of NiO, Fe ₂ O ₃ , Fe ₃ 0 ₄ , Ti0 ₂ , CuO, and Co ₃ 0 ₄ ;

The dispersion medium is selected from the group consisting of water, hydrazine, hydrazine-dimethylformamide (DMF), hydrazine, hydrazine-dimethylacetamide (DMAc), N-2-methylpyrrolidone (NMP), tetrahydrofuran (THF), One or more of ethanol and methanol;

(2) the obtained slurry is coated by a sol-gel method, a hydrothermal reaction method, a microwave chemical method or a high-temperature solid phase method to obtain a lithium ion battery composite anode material; the lithium ion battery composite type The anode material includes the transition metal oxide, and a coating layer coated on the surface of the transition metal oxide, and the material of the coating layer includes Li ₄ Ti ₅ 0 ₁₂ .

The specific operation of the microwave chemical method is as follows: drying the slurry at 100 to 120 ° C to obtain a precursor The body material, the precursor material is placed in an industrial microwave oven, heated to 600-800 ° C at 10 ° C / min, incubated for 1-4 hours, with the furnace cooling, the lithium-ion battery composite anode material is obtained .

The specific operation of the high-temperature solid phase method is: drying the slurry at 100-120 ° C to obtain a precursor material, and the precursor material is placed in a muffle furnace and sintered at 400-900 ° C. 0.5 to 10 hours, the furnace is cooled, and the lithium ion battery composite anode material is obtained.

The specific operation of the sol-gel method is as follows: drying the slurry at 60-80 ° C to obtain a precursor material, and placing the precursor material in a fluorocarbon furnace at 500-700 ° C for sintering 1 ~5 hours, after cooling to room temperature with the furnace, a lithium ion battery composite anode material is obtained.

The specific operation of the hydrothermal reaction method is: transferring the slurry into a hydrothermal reaction kettle, performing a hydrothermal ion exchange reaction at 150 to 160 ° C for 8 to 12 hours to obtain a black precipitate, and then placing the black precipitate. The heat treatment is performed in a muffle furnace at 500 to 600 ° C for 1 to 3 hours, and the furnace is cooled to room temperature to obtain the lithium ion battery composite anode material.

The specific description of the transition metal oxide and Li ₄ Ti ₅ 0 ₁₂ is as described above, and will not be described herein.

In order to improve the electrical conductivity of the lithium ion battery composite anode material, the coating material may further include a conductive additive, that is, a conductive additive is added in the step (1), and a lithium source, a titanium source, and a transition metal to be coated. The oxide is uniformly dispersed in a dispersion medium to form a slurry.

The conductive additive is one or more of artificial graphite, natural graphite, acetylene black, carbon black, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, phenolic resin, and sucrose. The conductive additive accounts for 1% to 5% of the total mass of the lithium ion battery composite negative electrode material.

A method for preparing a composite material of a lithium ion battery composite anode provided by the second aspect of the present invention provides a high capacity and a stable structure of the lithium ion battery composite anode material, which does not react with the electrolyte. Reaction, no agglomeration, lithium ion diffusion coefficient, so that lithium ion battery With high durability and cycle stability, it can improve the rate performance of lithium-ion batteries.

In a third aspect, an embodiment of the present invention provides a lithium ion battery, including a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte, and a battery case, the negative electrode sheet including a current collector and lithium ions coated on the surface of the current collector a battery composite type negative electrode material, the lithium ion battery composite type negative electrode material comprising a transition metal oxide, and a coating layer coated on a surface of the transition metal oxide, the transition metal oxide including NiO, Fe ₂ 0 ₃ And one or more of Fe ₃ 0 ₄ , Ti0 ₂ , CuO and Co ₃ 0 ₄ , and the material of the coating layer comprises Li ₄ Ti ₅ 0 ₁₂ .

The lithium ion battery provided by the third aspect of the embodiment of the present invention has a long cycle life and has excellent discharge capacity and rate performance.

The advantages of the embodiments of the present invention will be set forth in part in the description which follows. DRAWINGS

1 is a TEM image of a lithium ion battery composite anode material prepared in Example 1 of the present invention; FIG. 2 is a comparison diagram of cycle performance of a lithium ion battery obtained in Example 1 and Comparative Example 1, and FIG. 3 is an embodiment of the present invention; Figure 2 is a comparison chart of the cycle performance of the lithium ion battery obtained in Example 2 and Comparative Example 2; Figure 4 is a comparison of the cycle performance of the lithium ion battery obtained in Example 3 and Comparative Example 3 of the present invention; Figure 5 is a fourth embodiment and a comparative example of the present invention. The cycle performance comparison chart of the obtained lithium ion battery; Fig. 6 is a comparison chart of the cycle performance of the lithium ion battery obtained in Example 5 and Comparative Example 5 of the present invention. detailed description

The following is a preferred embodiment of the embodiments of the present invention. It should be noted that those skilled in the art can make some modifications without departing from the principles of the embodiments of the present invention. These improvements and retouchings are also considered to be within the scope of protection of embodiments of the present invention.

The embodiments of the present invention are further described below in various embodiments. The embodiments of the present invention are not limited to the specific embodiments below. Changes can be implemented as appropriate within the scope of the invariable principal rights.

The first aspect of the present invention provides a lithium ion battery composite anode material, which solves the problem that the metal oxide anode material is easy to agglomerate and easily decomposes with the electrolyte, thereby causing the first irreversible capacity of the battery and poor cycle performance. problem. A second aspect of the embodiments of the present invention provides a method for preparing a composite material of a lithium ion battery composite type. A third aspect of the embodiments of the present invention provides a lithium ion battery.

The embodiment of the present invention has no limitation on the position of the transition metal oxide in the lithium ion battery composite anode material, and is coated in the coating layer; the embodiment of the present invention is applicable to the transition metal oxide. The particle size is not particularly limited and can be coated in the coating layer.

The coating layer has a thickness of 50 to 8000 nm. In the embodiment, the thickness of the coating layer is 1000 to 4000 nm.

The transition metal oxide accounts for 10% to 95% of the total mass of the lithium ion battery composite anode material.

In this embodiment, the transition metal oxide accounts for 60% to 80% of the total mass of the lithium ion battery composite negative electrode material.

The transition metal oxide is selected from the group consisting of NiO (nickel oxide), Fe ₂ 0 ₃ (iron oxide), Fe ₃ 0 ₄ (triiron tetroxide), Ti0 ₂ (titanium oxide), CuO (copper oxide), and Co ₃ 0 One or more of ₄ (cobalt oxide). When the transition metal oxide is two or more, the ratio between the different transition metal oxides is not Special restrictions.

Since Li ₄ Ti ₅ 0 ₁₂ has low electron conductance and ion conductivity, in order to improve the electrical conductivity of the lithium ion battery composite anode material, the material of the coating layer may further include a conductive addition agent.

The conductive additive is uniformly distributed in the coating layer, and is located in the vicinity of the Li ₄ Ti ₅ 0 ₁₂ material, that is, the conductive additive is doped into the material of the ₄ 13⁄40 ₁₂ material, and the mixed metal oxide surface is formed into a mixed coating. Floor.

A lithium ion battery composite anode material provided by the first aspect of the present invention includes a transition metal oxide and a coating layer coated on the surface of the transition metal oxide, wherein the transition metal oxide is selected from the group consisting of NiO (oxidation) One or more of nickel), Fe ₂ 0 ₃ (iron oxide), Fe ₃ 0 ₄ (triiron tetroxide), Ti0 ₂ (titanium oxide), CuO (copper oxide), and Co ₃ 0 ₄ (cobalt oxide) Kind. These transition metal oxides have a high lithium insertion capacity (>600 mAh/g), which enables the lithium ion battery composite anode material to have a higher capacity; the cladding material includes Li ₄ Ti ₅ 0 ₁₂ , which has the following Large advantages: (1) 1^ ₄ 13⁄40 ₁₂ is a "zero strain" electrode material. During lithium ion intercalation-deintercalation, the volume change is small and the structure is stable, so it has excellent cycle performance; (2) ₄ 13⁄40 ₁₂ It has a three-dimensional lithium ion channel, and its lithium ion diffusion coefficient is one order of magnitude larger than that of the carbon-based anode material, which can improve the rate performance of the lithium battery; (3) Li ₄ Ti ₅ 0 _{12 has} an equilibrium potential of about 1.55 V, which can effectively prevent lithium metal deposition. Improve the safety performance of the lithium ion battery. At the same time, due to the high lithium insertion potential, the SEI film formation potential is not reached. The electrolyte does not undergo reductive decomposition on the surface of Li ₄ Ti ₅ 0 ₁₂ , which is beneficial to maintain the stability of the electrolyte and improve the cycle performance. Therefore, the present invention coats the surface of the transition metal oxide with Li ₄ Ti ₅ 0 _{12 to} coat the active site on the surface of the transition metal oxide, thereby Effectively protects transition metal oxides, prevents transition metal oxides from reacting with electrolytes, prevents agglomeration of transition metal oxides, and enables high-capacity lithium-ion battery composite anode materials with good cycle stability and durability. . In addition, since 1^ ₄ 13⁄40 ₁₂ has a three-dimensional lithium ion channel, its lithium ion diffusion coefficient is large, so that the rate performance of the lithium ion battery can be improved. Moreover, the lithium insertion potential of these transition metal oxide materials is close to that of Li ₄ Ti ₅ 0 ₁₂ , so that the lithium ion battery composite anode material can have a smooth and uniform charge and discharge platform.

In a second aspect, an embodiment of the present invention provides a method for preparing a lithium ion battery composite anode material, comprising the following steps:

(2) the obtained slurry is coated by a sol-gel method, a hydrothermal reaction method, a microwave chemical method or a high-temperature solid phase method to obtain a lithium ion battery composite anode material; the lithium ion battery composite type The anode material includes the transition metal oxide, and a coating layer coated on the surface of the transition metal oxide, and the material of the coating layer includes Li ₄ Ti ₅ 0 ₁₂ . The embodiment of the present invention has no limitation on the position of the transition metal oxide in the lithium ion battery composite anode material, and is coated in the coating layer; the embodiment of the present invention is applicable to the transition metal oxide. The particle size is not particularly limited and can be coated in the coating layer.

The transition metal oxide is selected from the group consisting of NiO (nickel oxide), Fe ₂ 0 ₃ (iron oxide), Fe ₃ 0 ₄ (triiron tetroxide), Ti0 ₂ (titanium oxide), CuO (copper oxide), and Co ₃ 0 One or more of ₄ (cobalt oxide). When the transition metal oxide is two or more kinds, the ratio between the different transition metal oxides is not particularly limited.

The coated raw material lithium source and the titanium source are added in a stoichiometric ratio of Li ₄ Ti ₅ 0 ₁₂ .

The dispersion medium is selected from the group consisting of water, hydrazine, hydrazine-dimethylformamide (DMF), hydrazine, hydrazine-dimethylacetamide (DMAc), N-2-methylpyrrolidone (NMP), tetrahydrofuran (THF), One or more of ethanol and methanol. When the dispersion medium is used in combination of two or more kinds, the ratio between the different dispersion mediums is not particularly limited.

The specific operation of the hydrothermal reaction method is: transferring the slurry into a hydrothermal reaction kettle, performing a hydrothermal ion exchange reaction at 150 to 160 ° C for 8 to 12 hours to obtain a black precipitate, and then placing the black precipitate. At 500~600 The heat treatment in the muffle furnace of °C is for 1-3 hours, and the lithium ion battery composite anode material is obtained by cooling to room temperature with the furnace.

The specific operation of the microwave chemical method is as follows: drying the slurry at 100-120 ° C to obtain a precursor material, placing the precursor material in an industrial microwave oven, and heating to 600 at 10 ° C / min. ~800 ° C, heat preservation for 1 to 4 hours, with the furnace cooling, the lithium ion battery composite anode material is obtained.

The specific description of the transition metal oxide and the lithium titanate Li ₄ Ti ₅ 0 ₁₂ is as described above, and will not be described herein.

A method for preparing a composite material of a lithium ion battery composite anode provided by the second aspect of the present invention provides a high capacity and a stable structure of the lithium ion battery composite anode material, which does not react with the electrolyte. The reaction, no agglomeration, and a large lithium ion diffusion coefficient, can make the lithium ion battery have high durability and cycle stability, and can improve the rate performance of the lithium ion battery. In a third aspect, an embodiment of the present invention provides a lithium ion battery, including a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte, and a battery case, the negative electrode sheet including a current collector and lithium ions coated on the surface of the current collector a battery composite type negative electrode material, the lithium ion battery composite type negative electrode material comprising a transition metal oxide, and a coating layer coated on a surface of the transition metal oxide, the transition metal oxide including NiO, Fe ₂ 0 ₃ And one or more of Fe ₃ 0 ₄ , Ti0 ₂ , CuO and Co ₃ 0 ₄ , and the material of the coating layer comprises Li ₄ Ti ₅ 0 ₁₂ .

Embodiment 1

A preparation method of a lithium ion battery composite anode material, comprising the following steps:

(1) Weigh out 8.4 g of lithium hydroxide (LiOH.H ₂ 0) and 20 g of titanium dioxide in 150 mL of deionized water; add 2.3 g of acetylene black to separate the hooks; then add 89.7 g of Fe ₂ 0 ₃ to stir and disperse. , obtaining a thick slurry;

(2) The thick slurry is dried in a drying oven at 110 ° C to obtain a precursor material, and the precursor material is placed in an industrial furnace, and the temperature is raised to 700 ° C at a rate of 10 ° C / min, and the temperature is maintained for 1 hour. The furnace was cooled to room temperature to obtain a composite anode material in which Li ₄ Ti ₅ 0 _{12 was} coated with Fe ₂ 0 ₃ .

Method for preparing lithium ion battery

The lithium ion battery composite anode material, the conductive carbon and the binder polyvinylidene fluoride PVDF obtained in the present embodiment are uniformly mixed in a mass ratio of 92:4:4 in N-2-methylpyrrolidone (NMP) to obtain a mixture. The slurry was applied to a 16 um aluminum foil, dried, and then cut into pole pieces, and the lithium piece was used as a counter electrode, and assembled into a CR2032 type button test battery. The packaged battery was carried out in an argon atmosphere glove box using a 1 mol/L LiPF ₆ ECDMC (1:1 ratio by volume) mixture and a Celgard 2400 separator.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a TEM image of a lithium ion battery composite negative electrode material obtained in Example 1 of the present invention. among them, 1 is Fe ₂ 0 ₃ particles, and 2 is a ₄ 13⁄40 ₁₂ coating layer. Figure 1 shows that the Fe ₂ O ₃ particles 1 are completely coated with the Li ₂ Ti ₅ 0 ₁₂ cladding layer 2, and the cladding layer has a thickness of 50 to 200 nm. In other embodiments, the cladding layer may be set to other thicknesses according to actual needs.

Embodiment 2

(1) uniformly disperse 13 g of lithium carbonate in 500 mL of water and absolute ethanol (wherein the volume ratio of water to ethanol is 4:1), and take butyl titanate 75 mL in a molar ratio of Ti: Li of 5:4. After diluting with 80 mL of absolute ethanol, adding to an aqueous solution of lithium carbonate dispersed in ethanol, stirring uniformly, and then adding 176 g of Co ₃ _{4 4,} stirring and dispersing uniformly to obtain a mixed slurry;

(2) The slurry is dried in a drying oven at 110 ° C to obtain a precursor material, and the obtained precursor material is sintered in a muffle furnace at 600 ° C for 4 hours, and cooled to room temperature with a furnace to obtain Li ₄ Ti ₅ 0 . ₁₂ coated Li ₃ 0 ₄ lithium ion battery composite anode material. The thickness of the cladding layer is 50 to 200 nm.

Method for preparing lithium ion battery

Same as the first embodiment.

Embodiment 3

Method for preparing lithium ion battery composite anode material

(1) Weigh 15.5 g of lithium nitrate, 20 g of titanium dioxide, and disperse in 200 mL of deionized water, and add 1.2 g of carbon black to disperse uniformly. Then, 18.2 g of Co ₃ 0 ₄ and 18.2 g of Fe ₂ 0 ₃ were added and stirred to obtain a thick shape. Slurry

(2) The slurry is dried in a drying oven at 110 ° C to obtain a precursor material, and the precursor material is placed in an industrial microwave oven, heated to 650 ° C at a rate of 10 ° C / min, kept for 2 hours, and cooled with the furnace. To room temperature, a lithium ion battery composite type negative electrode material in which lithium titanate Li ₄ Ti ₅ 0 _{12 was} coated with Co ₃ 0 ₄ and Fe ₂ 0 ₃ was obtained. The thickness of the cladding layer is 50 to 200 nm. Method for preparing lithium ion battery

Same as the first embodiment.

Embodiment 4

Method for preparing lithium ion battery composite anode material

(1) 20 g of lithium acetate was uniformly dispersed in an absolute ethanol solution, and 107 g of titanium isopropoxide was taken in a molar ratio of Ti: Li of 5:4, diluted with 200 mL of absolute ethanol, and added to the lithium acetate dispersed therein. In the aqueous ethanol solution, after stirring uniformly, 6.8 g of carbon nanotubes were added, and 120 g of NiO was added thereto, and the mixture was uniformly stirred and uniformly dispersed to obtain a gel-sol slurry;

(2) The gel-sol slurry was dried in a drying oven at 60 ° C to obtain a precursor material, which was sintered in a muffle furnace at 650 ° C for 2 hours, and cooled to room temperature with a furnace to obtain a Li ₄ Ti ₅ 0 ₁₂ package. NiO-coated lithium ion battery composite anode material. The thickness of the cladding layer is 50 to 200 nm.

Method for preparing lithium ion battery

Same as the first embodiment.

Embodiment 5

Method for preparing lithium ion battery composite anode material

(1) Weigh 8.4g of hydrated lithium hydroxide (LiOH.H ₂ 0 ), 20g of titanium dioxide dispersed in 250mL of deionized water, and disperse evenly; add 85.6g of copper oxide (CuO) and stir well to obtain a mixed liquid;

(2) Subsequently, the solution was transferred to a hydrothermal reaction vessel, and 4.5 g of conductive acetylene black was added for hydrothermal ion exchange reaction at 160 ° C for 10 h to obtain a black precipitate, and the black precipitate was placed in a muffle furnace at 500 ° C. The medium heat treatment was carried out for 2 hours, and the furnace was cooled to room temperature to obtain a Li ₄ Ti ₅ 0 ₁₂ coated copper oxide (CuO) lithium ion battery composite anode material. The thickness of the cladding layer is 50 to 200 nm.

Method for preparing lithium ion battery Same as the first embodiment.

Embodiment 6

Method for preparing lithium ion battery composite anode material

(1) Weigh hydrated lithium hydroxide (LiOH.H ₂ 0 ) 16.8g, titanium dioxide 40g dispersed in 150mL of deionized water; add 2.5g artificial graphite, and then add 5.5g of ferroferric oxide (Fe ₃ 0 ₄ ) Stirring and dispersing evenly to obtain a mixed slurry;

(2) The mixed slurry is dried in a drying oven at 110 ° C to obtain a precursor material, and the precursor material is placed in an industrial furnace, and the temperature is raised to 700 ° C at a rate of 10 ° C / min, and the temperature is maintained for 1 hour. The furnace was cooled to room temperature to obtain a lithium ion battery composite anode material of 1 ^ ₄ 13⁄40 ₁₂ coated with ferroferric oxide (Fe ₃ 0 ₄ ). The thickness of the cladding layer is 50 to 200 nm.

Method for preparing lithium ion battery

Same as the first embodiment.

Example 7

Method for preparing lithium ion battery composite anode material

(1) Weigh 15.5 g of lithium nitrate, 20 g of titanium dioxide dispersed in 500 mL of deionized water, add 5 g of carbon black, and then add 205 g of Co ₃ O ₄ and 205 g of NiO to fully stir and disperse to obtain a mixed slurry;

(2) The slurry is dried in a drying oven at 110 ° C to obtain a precursor material, and the precursor material is placed in an industrial microwave oven, heated to 650 ° C at a rate of 10 ° C / min, kept for 2 hours, and cooled with the furnace. To room temperature, a lithium ion battery composite negative electrode material in which Li ₄ Ti ₅ 0 _{12 was} coated with Co ₃ 0 ₄ and NiO was obtained. The thickness of the coating layer is 50 to 200 匪.

Method for preparing lithium ion battery

Same as the first embodiment.

Comparative example one The Fe ₂ O ₃ negative electrode material not coated with Li ₄ Ti ₅ 0 ₁₂ was assembled into a lithium ion battery in the same manner as in Example 1. Comparative example two

The Co ₃ 0 ₄ negative electrode material not coated with 1 ^ ₄ 13⁄40 ₁₂ was assembled into a lithium ion battery in the same manner as in Example 1. Comparative example three

The Fe ₂ O ₃ and Co ₃ 0 ₄ mixed anode materials not coated with Li ₄ Ti ₅ 0 ₁₂ were assembled into a lithium ion battery in the same manner as in Example 1.

Comparative example four

A nickel oxide (NiO) negative electrode material not coated with Li ₄ Ti ₅ 0 ₁₂ was assembled into a lithium ion battery in the same manner as in Example 1.

Comparative example five

A copper oxide (CuO) negative electrode material not coated with Li ₄ Ti ₅ 0 ₁₂ was assembled into a lithium ion battery in the same manner as in Example 1.

The lithium ion batteries produced in the above examples and comparative examples were experimental batteries for the performance test of the following effect examples. Effect embodiment

In order to strongly support the beneficial effects brought by the technical solutions of the embodiments of the present invention, the following performance tests are provided:

The lithium ion batteries prepared in the above examples and comparative examples were subjected to a charge and discharge cycle test using a battery performance tester. The test conditions are: charging cut-off voltage to 2.5V, discharge cut-off voltage to 0.5V, current density is 0.07mA/cm ² .

2 is a graph showing the cycle performance of a lithium ion battery obtained in Example 1 of the present invention and Comparative Example 1. As can be seen from FIG. 2, the first embodiment of the surface coated with ₄ 13⁄40 ₁₂ Fe ₂ O ₃ lithium ion battery composite anode material The first specific capacity was 845 mAh/g, and the first specific capacity of the uncoated Fe ₂ 0 ₃ material was 1000 mAh/g, but after 50 cycles, the specific capacity decreased to 430 mAh/g, only for the first time. 43% of the specific capacity; and the Fe ₂ 0 ₃ lithium ion battery composite anode material coated with Li ₄ Ti ₅ 0 _{12 has} a specific capacity decrease of 752 mAh/g after 50 cycles, which is 89% of the first specific capacity. The results show that the cycle properties of the Fe ₂ O ₃ material coated with Li ₄ Ti ₅ 0 ₁₂ are significantly improved.

3 is a comparison diagram of cycle performance of a lithium ion battery obtained in Example 2 and Comparative Example 2 of the present invention. It can be seen from FIG. 3 that the first specific specific capacity of the Co ₃ 0 ₄ lithium ion battery composite anode material coated with ₄ 11 ₅ 0 ₁₂ on the surface of the second embodiment is 930 mAh/g, and the comparative example is uncoated Co ₃ 0 . _{4 The} material's first specific capacity is HOOmAh/g, but after 50 cycles, its specific capacity decreases to 320 mAh/g, only 30% of the first specific capacity; and the surface is coated with Li ₄ Ti ₅ 0 ₁₂ Co ₃ after the material ₀₄ through 50 cycles, which is lower than the capacity of 838mAh / g, is 90% more than the first capacity; results show: the surface-coated material Li Co ₃ 0 ₄ ₄ Ti ₅ 0 _12, the cycle performance was Significant improvement.

4 is a graph showing the cycle performance of a lithium ion battery obtained in Example 3 of the present invention and Comparative Example 3. As can be seen from FIG. 4, the first specific capacity of the Fe ₂ O ₃ and Co ₃ 0 ₄ lithium ion battery composite anode materials coated with Li ₄ Ti ₅ 0 ₁₂ on the surface of the first embodiment is 860 mAh/g, uncoated. The first specific capacity of the Fe ₂ 0 ₃ and Co ₃ 0 ₄ mixed materials is 1080 mAh/g, but after 50 cycles, the specific capacity decreases to 368 mAh/g, only 34% of the first specific capacity; After 50 cycles of the Li ₂ Ti ₅ 0 ₁₂ Fe ₂ O ₃ and Co ₃ 0 ₄ materials, the specific capacity decreased to 798 mAh/g, which is 93% of the first specific capacity. The results show that the surface is coated with Li ₄ The Fe ₂ 0 ₃ and Co ₃ 0 ₄ materials of Ti ₅ 0 ₁₂ have a significant improvement in cycle performance.

Figure 5 is a graph showing the cycle performance of a lithium ion battery obtained in Example 4 and Comparative Example 4 of the present invention. It can be seen from Fig. 5 that the first specific capacity of the NiO material coated with Li ₄ Ti ₅ 0 ₁₂ on the surface of the fourth embodiment is 734 mAh/g, and the first specific capacity of the four uncoated NiO materials in the comparative example is 806 mAh/g. However, after 50 cycles, its specific capacity decreased to 290 mAh/g, only 36% of the first specific capacity; After 50 cycles of the ^0 material of 1^ ₄ 13⁄40 ₁₂ , the specific capacity decreased to 675 mAh/g, which is 92% of the first specific capacity. The results show that the surface of the NiO material coated with ₄ 13⁄40 _{12 has} a cycle performance. Significant improvement.

Figure 6 is a graph showing the cycle performance of a lithium ion battery obtained in Example 5 and Comparative Example 5 of the present invention. It can be seen from Fig. 6 that the first specific capacity of the CuO material coated with 1^ ₄ 13⁄40 ₁₂ on the surface of the fourth embodiment is 624 mAh/g, and the first specific capacity of the five uncoated CuO material is 700 mAh/g. However, after 50 cycles, the specific capacity decreased to 210 mAh/g, which is only 30% of the first specific capacity; while the CuO material coated with Li ₄ Ti ₅ 0 ₁₂ on the surface of Example 5 after 50 cycles, Its specific capacity decreased to 568 mAh/g, which is 91% of the first specific capacity. The results show that the cycle performance of CuO material coated with Li ₄ Ti ₅ 0 ₁₂ has been significantly improved.

Claims

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1. A composite anode material for a lithium ion battery, characterized in that it includes a transition metal oxide, and a coating layer coating the surface of the transition metal oxide, and the transition metal oxide includes NiO, Fe ₂ 0 _3. One or more of Fe ₃ 0 ₄ , Ti0 ₂ , CuO and Co ₃ 0 ₄ , and the material of the coating layer includes Li ₄ Ti ₅ 0 ₁₂ .

2. A composite negative electrode material for lithium ion batteries according to claim 1, characterized in that the thickness of the coating layer is 50~8000nm.

3. The composite negative electrode material for lithium ion batteries according to claim 1, wherein the transition metal oxide accounts for 10% to 95% of the total mass of the composite negative electrode material for lithium ion batteries.

4. A lithium-ion battery composite negative electrode material according to claim 1, characterized in that the material of the coating layer further includes a conductive additive, and the conductive additive is artificial graphite, natural graphite, acetylene black, carbon One or more of black, mesophase carbon microspheres, carbon nanotubes, carbon nanofibers, phenolic resin and sucrose, the conductive additive accounts for 1% to 5% of the total mass of the lithium-ion battery composite negative electrode material .

5. A method for preparing a composite negative electrode material for a lithium-ion battery, which is characterized by including the following steps:

(1) Stir and disperse the coating raw materials lithium source, titanium source and transition metal oxide to be coated in the dispersion medium to form a slurry;

The coating raw material lithium source is selected from one or more of lithium hydroxide, hydrated lithium hydroxide, lithium carbonate, lithium nitrate, lithium sulfate, lithium fluoride, lithium oxalate, lithium chloride and lithium acetate;

The coating raw material titanium source is selected from one or more of titanium dioxide, titanium tetrachloride, titanium trichloride, titanium isopropoxide, tetrabutyl titanate, butyl titanate and n-propyl titanate; The transition metal oxide is selected from one or more of NiO, Fe ₂ 0 ₃ , Fe ₃ 0 ₄ , Ti0 ₂ , CuO and Co ₃ 0 ₄ ;

The dispersion medium is selected from one or more of water, N,N-dimethylformamide, N,N-dimethylacetamide, N-2-methylpyrrolidone, tetrahydrofuran, ethanol and methanol;

(2) The obtained slurry is coated through a sol-gel method, a hydrothermal reaction method, a microwave chemical method or a high-temperature solid phase method to prepare a lithium-ion battery composite negative electrode material; the lithium-ion battery composite type The negative electrode material includes the transition metal oxide, and a coating layer covering the surface of the transition metal oxide. The material of the coating layer includes Li ₄ Ti ₅ 0 ₁₂ .

6. The method for preparing a composite negative electrode material for a lithium ion battery according to claim 5, wherein the transition metal oxide accounts for 10% to 95% of the total mass of the composite negative electrode material for a lithium ion battery.

7. The method for preparing composite negative electrode materials for lithium ion batteries according to claim 5, wherein the coating raw material further includes a conductive additive, and the conductive additive is artificial graphite, natural graphite, acetylene black, and carbon black. , one or more of mesophase carbon microspheres, carbon nanotubes, carbon nanofibers, phenolic resin and sucrose, and the conductive additive accounts for 1% to 5% of the total mass of the lithium-ion battery composite negative electrode material.

8. The preparation method of composite negative electrode material for lithium ion batteries according to claim 5, characterized in that the specific operation of the microwave chemical method is: drying the slurry at 100~120°C to obtain a precursor The precursor material is placed in an industrial microwave oven, heated to 600~800°C at 10°C/min, kept for 1~4 hours, and then cooled in the furnace to obtain the lithium ion battery composite negative electrode material. .

9. The preparation method of composite negative electrode material for lithium ion batteries according to claim 5, characterized in that the specific operation of the high temperature solid phase method is: drying the slurry at 100~120°C to obtain Precursor material: The precursor material is placed in a muffle furnace and sintered at 400 to 900°C for 0.5 to 10 hours, and then cooled in the furnace to obtain the composite negative electrode material for the lithium ion battery.

10. A lithium-ion battery, including a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte and a battery casing, characterized in that the negative electrode sheet includes a current collector and a lithium-ion battery composite negative electrode coated on the surface of the current collector material, the lithium ion battery composite negative electrode material includes a transition metal oxide, and a coating layer covering the surface of the transition metal oxide, the transition metal oxide includes NiO, Fe ₂ 0 ₃ , Fe ₃ 0 _4. One or more of Ti0 ₂ , CuO and Co ₃ 0 ₄ , and the material of the coating layer includes Li ₄ Ti ₅ 0 ₁₂ .