阅读说明：本技术 一种高电压高容量锂离子电池正极材料及其制备方法 (High-voltage high-capacity lithium ion battery anode material and preparation method thereof ) 是由 张鹏 谢超 谢健楠 陈丽霞 周贻森 杨章应 朱强 韩改格 金明钢 于 2020-04-23 设计创作，主要内容包括：本发明公开了一种高电压高容量锂离子电池正极材料及其制备方法。本发明的制备方法为：先用高温固相反应法结合机械球磨合成具有层状结构的HT-Li-CoO<Sub>2</Sub>型的Li<Sub>1+x</Sub>Mg<Sub>x</Sub>Co<Sub>1-x</Sub>O<Sub>2</Sub>粉体材料；随后利用Pechini法合成NASICON型的Li<Sub>1.4</Sub>Al<Sub>0.4</Sub>Ti<Sub>1.6</Sub>(PO<Sub>4</Sub>)<Sub>3</Sub>前驱体凝胶,利用机械球磨法涂覆于Li<Sub>1+x</Sub>Mg<Sub>x</Sub>Co<Sub>1-x</Sub>O<Sub>2</Sub>粉体材料表面,并利用高温反应在粉体材料表面原位合成Li<Sub>1.4</Sub>Al<Sub>0.4</Sub>Ti<Sub>1.6</Sub>(PO<Sub>4</Sub>)<Sub>3</Sub>固体锂离子导体膜。使用本发明正极材料的锂离子电池在充电截止电压4.5V下具有长循环寿命,甚至可以高达4.6V,相应的正极放电容量超过180mAh/g；且此材料具有制备工艺相对简单,使用的原材料丰富、价格低等优点,适合于大规模工业化生产,具有广阔的应用前景。(The invention discloses a high-voltage high-capacity lithium ion battery anode material and a preparation method thereof. The preparation method comprises the following steps: firstly, synthesizing HT-Li-CoO with a laminated structure by combining a high-temperature solid-phase reaction method and mechanical ball milling 2 Form of Li 1+x Mg x Co 1‑x O 2 A powder material; subsequently, NASICON type Li was synthesized by the Pechini method 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 Precursor gelGlue applied to Li by mechanical ball milling 1+x Mg x Co 1‑x O 2 In-situ synthesis of Li on the surface of powder material by high-temperature reaction 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 A solid lithium ion conductor film. The lithium ion battery using the anode material has long cycle life under the charge cut-off voltage of 4.5V, even can reach 4.6V, and the corresponding anode discharge capacity exceeds 180 mAh/g; the material has the advantages of relatively simple preparation process, abundant used raw materials, low price and the like, is suitable for large-scale industrial production, and has wide application prospect.)

1. A preparation method of a high-voltage high-capacity lithium ion battery anode material is characterized by comprising the following steps:

1) firstly, synthesizing HT-Li-CoO with a laminated structure by a high-temperature solid-phase reaction method and mechanical ball milling₂Form of Li_{1+ x}Mg_xCo_1-xO₂Powder material, wherein x is 0.01-0.075;

2) synthesis of NASICON type Li by Pechini method_1.4Al_0.4Ti_1.6(PO₄)₃A solid electrolyte precursor gel;

3) the gel is coated on Li by adopting a mechanical ball milling method_1+xMg_xCo_1-xO₂In-situ synthesis of Li on the surface of powder material by high-temperature reaction_1.4Al_0.4Ti_1.6(PO₄)₃Solid lithium ion conductor film, the final material prepared being (y) wt% Li_1.4Al_0.4Ti_1.6(PO₄)₃@(100-y)wt％Li_1+xMg_xCo_1-xO₂And y is 2.5-7.5.

2. The method for preparing the high-voltage high-capacity lithium ion battery cathode material according to claim 1, wherein the specific process of the step 1) is as follows: weighing lithium carbonate, cobaltosic oxide and magnesium oxide according to the synthesized anode material, ball-milling for several hours, uniformly mixing, carrying out heat treatment for 11-13 hours in an air atmosphere at 550-650 ℃, then carrying out wet ball-milling for 8-12 minutes, drying, carrying out heat treatment for 11-13 hours in an air atmosphere at 850-950 ℃, finally carrying out wet ball-milling for 1-3 hours, drying, ball-milling for 20-40 seconds, and sieving with a 300-500-mesh sieve.

3. The method for preparing the high-voltage high-capacity lithium ion battery cathode material according to claim 1, wherein the specific process of the step 2) is as follows: the preparation is 1.8-2.2mol L^-1Adding a proper amount of glycol into the citric acid aqueous solution, and stirring for several hours to obtain a chelate; then tetrabutyl titanate is added, heating is carried out at 75-85 ℃, and magnetic stirring is carried out continuously until clear sol is obtained, and then anhydrous lithium nitrate, anhydrous ammonium dihydrogen phosphate and aluminum nitrate nonahydrate are sequentially added into the sol, and the mixture is added at 40-60 ℃ and stirred continuously until white gel is obtained.

4. The method for preparing the high-voltage high-capacity lithium ion battery cathode material according to any one of claims 1 to 3, wherein the specific process of the step 3) is as follows: said Li_1.4Al_0.4Ti_1.6(PO₄)₃Gels and Li_1+xMg_xCo_1-xO₂Mixing the powder materials, mechanically ball-milling for 0.5-2 hours, then carrying out heat treatment for 0.5-1.5 hours in an air atmosphere at 650 ℃ plus 550 ℃, then carrying out mechanical ball-milling for a plurality of minutes again, then carrying out heat treatment for more than 3 hours in an air atmosphere at 950 ℃ plus 850 ℃, then adding xylene to carry out wet ball-milling for less than 1 hour, drying, and filtering by using a 500-mesh sieve at 300-.

5. The method for preparing the high-voltage high-capacity lithium ion battery cathode material according to claim 4, wherein the water content of the white gel prepared in the step 2) is controlled to be 5-15%.

6. The method for preparing the high-voltage high-capacity lithium ion battery cathode material according to claim 2, wherein a solvent used in the wet ball milling is xylene.

7. The method for preparing the positive electrode material of the high-voltage high-capacity lithium ion battery according to claim 4, wherein the temperature of the first heat treatment in the step 3) is 600 ℃.

8. The method for preparing the positive electrode material of the high-voltage high-capacity lithium ion battery according to claim 4, wherein the temperature of the second heat treatment in the step 3) is 900 ℃.

9. The high-voltage high-capacity lithium ion battery cathode material prepared by the preparation method of any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of lithium ion battery anode materials, in particular to a high-voltage high-capacity lithium ion battery anode material and a preparation method thereof.

Background

The rechargeable lithium ion battery is widely applied to various 3C electronic products, becomes an indispensable part of our lives in the era of mobile internet, and has wider application space with the advent of the era of 5G and the era of internet of things in future. The current positive electrode material used for lithium ion batteries for 3C electronic products is lithium cobaltate (LiCoO)₂) Mainly because the unit volume capacity is the highest, but the theoretical capacity of the lithium cobaltate for stable circulation is generally not more than 145mAh/g, the charge cut-off voltage is not more than 4.2V, namely, only 1 Li can be extracted from every two lithium cobaltates⁺Otherwise, the structure is unstable, so that the volume energy density of the current 3C lithium ion battery product is generally not more than 450Wh/L, and the market demand is difficult to meet.

If a further increase in energy density is required, the remaining Li has to be extracted further⁺I.e. to improve the charge cutoffVoltage cut, but in theory LiCoO₂The layered structure of (a) can subsequently collapse, leading to rapid failure of the cell, as demonstrated by numerous experiments.

Disclosure of Invention

The invention aims to solve the problem of LiCoO₂The positive electrode material releases at most half of Li in order to maintain structural stability⁺The invention provides a high-voltage high-capacity lithium ion battery positive electrode material and a preparation method thereof, which aims to improve the charge cut-off voltage and greatly improve the actual capacity upper limit of the positive electrode material.

Therefore, the technical scheme adopted by the invention is as follows: a preparation method of a high-voltage high-capacity lithium ion battery anode material comprises the following steps:

1) firstly, synthesizing HT-Li-CoO with a laminated structure by a high-temperature solid-phase reaction method and mechanical ball milling₂Form of Li_1+xMg_xCo_1-xO₂Powder material, wherein x is 0.01-0.075;

2) synthesis of NASICON type Li by Pechini method_1.4Al_0.4Ti_1.6(PO₄)₃A solid electrolyte precursor gel;

3) the gel is coated on Li by adopting a mechanical ball milling method_1+xMg_xCo_1-xO₂In-situ synthesis of Li on the surface of powder material by high-temperature reaction_1.4Al_0.4Ti_1.6(PO₄)₃Solid lithium ion conductor film, the final material prepared being (y) wt% Li_1.4Al_0.4Ti_1.6(PO₄)₃@(100-y)wt％Li_1+xMg_xCo_1-xO₂And y is 2.5-7.5.

The invention is in LiCoO₂Middle doped with magnesium ion (Mg)²⁺) At the same time, the surface of the anode material is coated with high Li⁺A solid electrolyte membrane of conductivity, thereby making the anode layered material remove more Li⁺And greatly prolongs the cycle life.

Further, the specific process of step 1) is as follows: weighing lithium carbonate, cobaltosic oxide and magnesium oxide according to the synthesized anode material, ball-milling for several hours, uniformly mixing, carrying out heat treatment for 11-13 hours in an air atmosphere at 550-650 ℃, then carrying out wet ball-milling for 8-12 minutes, drying, carrying out heat treatment for 11-13 hours in an air atmosphere at 850-950 ℃, finally carrying out wet ball-milling for 1-3 hours, drying, ball-milling for 20-40 seconds, and sieving with a 300-500-mesh sieve.

Further, the specific process of step 2) is as follows: the preparation is 1.8-2.2mol L^-1Adding a proper amount of glycol into the citric acid aqueous solution, and stirring for several hours to obtain a chelate; then tetrabutyl titanate is added, heating is carried out at 75-85 ℃, and magnetic stirring is carried out continuously until clear sol is obtained, and then anhydrous lithium nitrate, anhydrous ammonium dihydrogen phosphate and aluminum nitrate nonahydrate are sequentially added into the sol, and the mixture is added at 40-60 ℃ and stirred continuously until white gel is obtained.

Further, the specific process of step 3) is as follows: said Li_1.4Al_0.4Ti_1.6(PO₄)₃Gels and Li_{1+ x}Mg_xCo_1-xO₂Mixing the powder materials, mechanically ball-milling for 0.5-2 hours, then carrying out heat treatment for 0.5-1.5 hours in an air atmosphere at 650 ℃ plus 550 ℃, then carrying out mechanical ball-milling for a plurality of minutes again, then carrying out heat treatment for more than 3 hours in an air atmosphere at 950 ℃ plus 850 ℃, then adding xylene to carry out wet ball-milling for less than 1 hour, drying, and filtering by using a 500-mesh sieve at 300-.

Further, the water content of the white gel prepared in the step 2) is controlled to be 5-15%.

Further, xylene is used as a solvent for wet ball milling.

Further, in step 3), the temperature of the first heat treatment is preferably 600 ℃.

Further, in step 3), the temperature of the second heat treatment is preferably 900 ℃.

The invention also provides the high-voltage high-capacity lithium ion battery anode material prepared by the preparation method.

Compared with the existing materials, the invention has the following advantages:

1) the charge cut-off voltage of the lithium battery can be increased to more than 4.5V, and the release capacity of the anode material exceeds 180 mAh/g;

2) the lithium battery can be stably cycled for more than 300 circles, and the capacity retention rate of the positive electrode is more than 80%.

Compared with the prior art, the method has the following advantages:

1) the preparation method is simple, low in cost, rich in raw materials, low in price, suitable for large-scale industrial production and wide in application prospect;

2) the gel precursor is used for generating a film in situ, so that the combination is tight, and the coating property is good;

3)Li_1.4Al_0.4Ti_1.6(PO₄)₃crystallization temperature of heat treatment and Li_1+xMg_xCo_1-xO₂The temperature range of the powder heat treatment synthesis is similar, the crystallinity is good, and the impurities are few.

Drawings

FIG. 1(a) is a graph showing the cycle profile of a battery according to example 1 of the present invention; FIG. 1(b) is a graph showing the charge capacity and charge-discharge efficiency of a battery according to example 1 of the present invention;

FIG. 2(a) is a graph showing the cycle profile of a battery according to example 2 of the present invention; FIG. 2(b) is a graph showing the charge capacity and charge-discharge efficiency of a battery according to example 2 of the present invention;

FIG. 3(a) is a graph showing the cycle profile of a battery according to example 3 of the present invention; FIG. 3(b) is a graph showing the charge capacity and charge-discharge efficiency of a battery according to example 3 of the present invention;

FIG. 4(a) is a graph showing the cycle characteristics of a battery according to example 4 of the present invention; FIG. 4(b) is a graph showing the charge capacity and charge-discharge efficiency of the battery of example 4 of the present invention;

FIG. 5(a) is a graph showing the cycle characteristics of a battery according to example 5 of the present invention; FIG. 5(b) is a graph showing the charge capacity and charge-discharge efficiency of the battery of example 5 of the present invention;

FIG. 6 shows 5 wt% Li according to the present invention_1.4Al_0.4Ti_1.6(PO₄)₃@95wt％Li_1.05Mg_0.05Co_0.95O₂Xrd test chart of (1);

FIG. 7(a) is a graph showing the cycle curve of a battery according to example 7 of the present invention; fig. 7(b) is a graph showing the cycle curve of another battery according to example 7 of the present invention.

FIG. 8 is a graph showing the cycle profile of a comparative example 1 cell of the present invention;

FIG. 9(a) is a graph showing the cycle profile of a comparative example 2 cell of the present invention; FIG. 9(b) is a graph showing charge capacity and charge-discharge efficiency of a battery of comparative example 2 of the present invention;

FIG. 10(a) is a graph showing the cycle profile of a comparative example 3 cell of the present invention; FIG. 10(b) is a graph showing the charge capacity and charge-discharge efficiency of a battery of comparative example 3 of the present invention.

Detailed Description

The invention is further described with reference to the drawings and the detailed description.

A preparation method of a high-voltage high-capacity lithium ion battery anode material comprises the following steps:

1) firstly, synthesizing HT-Li-CoO with a laminated structure by a high-temperature solid-phase reaction method and mechanical ball milling₂Form of Li_1+xMg_xCo_1-xO₂Powder material, wherein x is 0.01-0.075;

2) synthesis of NASICON type Li by Pechini method_1.4Al_0.4Ti_1.6(PO₄)₃A solid electrolyte precursor gel;

3) the gel is coated on Li by adopting a mechanical ball milling method_1+xMg_xCo_1-xO₂In-situ synthesis of Li on the surface of powder material by high-temperature reaction_1.4Al_0.4Ti_1.6(PO₄)₃Solid lithium ion conductor film, the final material prepared being (y) wt% Li_1.4Al_0.4Ti_1.6(PO₄)₃@(100-y)wt％Li_1+xMg_xCo_1-xO₂And y is 2.5-7.5.

The specific process of step 1) is as follows: weighing lithium carbonate, cobaltosic oxide and magnesium oxide according to the synthesized positive electrode material (such as synthesized Li)_1.05Mg_0.05Co_0.95O₂Respectively weighing 7.625g of cobaltosic oxide, 3.879g of lithium carbonate and 0.202g of magnesium oxide), ball-milling for hours, uniformly mixing,firstly, carrying out heat treatment for 12 hours at 600 ℃ in air atmosphere, then carrying out wet ball milling on the prepared material for 10 minutes by adding dimethylbenzene, drying, then carrying out heat treatment for 12 hours at 900 ℃ in air atmosphere, finally carrying out wet ball milling on the prepared material for 2 hours by adding dimethylbenzene, drying, carrying out ball milling for 30 seconds, and sieving by using a 400-mesh sieve.

The specific process of step 2) is as follows: configuration 2.0mol L^-1Adding a proper amount of glycol into the citric acid aqueous solution, and stirring for several hours to obtain a chelate; and then tetrabutyl titanate is added, the mixture is heated at 80 ℃ and is continuously stirred by magnetic force until clear sol is obtained, and then anhydrous lithium nitrate, anhydrous ammonium dihydrogen phosphate and aluminum nitrate nonahydrate are sequentially added into the sol and are added at 40-60 ℃ and are continuously stirred until white gel with solid content of about 10% is obtained. The solid content was determined by TG-DSC synchronous thermal analyzer.

The specific process of step 3) is as follows: said Li_1.4Al_0.4Ti_1.6(PO₄)₃Gels and Li_1+xMg_xCo_1-xO₂Mixing the powder materials, mechanically ball-milling for 1 hour, then carrying out heat treatment for 1 hour in an air atmosphere at 600 ℃, then carrying out mechanical ball-milling for a plurality of minutes again, then carrying out heat treatment for more than 3 hours in an air atmosphere at 900 ℃, then adding dimethylbenzene to carry out wet ball-milling for less than 1 hour, drying, and filtering by using a 400-mesh sieve.

The positive electrode material prepared by the above method is applied to a battery, and details are shown in the following examples.