CN107565122A - A kind of preparation method of doping type nickel-cobalt lithium manganate cathode material - Google Patents

Abstract

The invention belongs to the technical field of lithium ion batteries, in particular to a method for preparing a doped nickel-cobalt lithium manganate cathode material. The chemical formula of the nickel-cobalt lithium manganese oxide is Li(Nia Co _b Mn 1- _{a -b} ) _1-x Nb _x O ₂ , where 0≤x≤0.1, 0.3≤a≤0.8, and 0.05≤b≤0.4. The specific process of its preparation is as follows: the nickel-cobalt-manganese precursor, niobium source and lithium salt are ball-milled and mixed according to a certain ratio, and the doped nickel-cobalt-manganese lithium manganese oxide is obtained after pre-calcination, secondary ball milling, and calcination in a high-temperature atmosphere furnace. Cathode material. The preparation method involved in the present invention has a simple process and is easy to realize industrialization. The obtained doped nickel-cobalt lithium manganese oxide positive electrode material has excellent cycle stability under high voltage, which solves the problem of the nickel-cobalt lithium manganese oxide positive electrode material under high voltage. capacity fading behavior.

Description

A kind of preparation method of doped nickel cobalt lithium manganese oxide cathode material

technical field

The invention belongs to the technical field of lithium ion batteries, and in particular relates to a preparation method of a doped nickel-cobalt lithium manganese oxide positive electrode material.

Background technique

As an important energy storage device, lithium-ion batteries have been widely used in electronic products such as mobile phones and computers. Traditional lithium-ion batteries mainly use lithium cobaltate as the positive electrode material, but due to the high price and low energy density of lithium cobaltate, it is urgent to find a high energy density positive electrode material. At present, the positive electrode materials that have been studied more mainly include ternary positive electrode materials with layered structure, lithium-rich manganese-based materials, lithium manganese oxide and lithium iron phosphate, etc. Among them, nickel-cobalt lithium manganese oxide ternary positive electrode materials are due to their high energy density. It is favored by people, especially the high-nickel-based ternary material, whose specific capacity can reach 200mAh/g. The chemical formula of the lithium nickel cobalt manganese oxide is Li(Nia Co _b Mn _{1-ab ) 1-x} Nb _x O ₂ , where 0≤x≤0.1, 0.3 ≤ a ≤0.8, and 0.05 ≤ b ≤ 0.4. However, nickel-cobalt lithium manganese oxide cathode materials face problems such as poor structural stability and rapid capacity fading during high-voltage cycling, which limits its commercial application. In view of the problems faced by nickel-cobalt-lithium manganese oxide materials, there are currently two main ways to improve them, namely ion doping and surface coating. As an effective means, ion doping can improve the structural stability of the host material, especially at high voltage, a small amount of inert ion doping can stabilize the layered structure of the nickel-cobalt-lithium-manganese-oxide material, thus improving Cycling stability of such materials at high voltages. Traditional ion doping is often achieved by sol-gel or co-precipitation methods. These two methods are cumbersome and expensive. Therefore, it is of great significance to develop a simple and inexpensive doping method.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a doped nickel-cobalt lithium manganese oxide positive electrode material to solve the problem of poor cycle stability of the material under high voltage.

To achieve the above object, the technical scheme of the present invention is as follows:

A preparation method of a doped nickel cobalt lithium manganese oxide positive electrode material, comprising the following steps:

(1) Mix nickel-cobalt-manganese precursor, niobium source and lithium salt in a planetary ball mill;

(2) Pre-burning the resulting mixture in a muffle furnace;

(3) Secondary ball milling and mixing of pre-burned materials in a planetary ball mill;

(4) The resulting mixture is calcined in a high-temperature tubular atmosphere furnace to obtain the final product.

As a preference of the above technical solution, in step (1), the molar ratio of the nickel-cobalt-manganese precursor, the niobium source, and the lithium salt is 1.0: 0.002-0.1: 0.5-1.1.

As a preferred technical solution, in step (1), the nickel-cobalt-manganese precursor is selected from Ni _1/3 Co _1/3 Mn _1/3 (OH) ₂ , Ni _0.5 Co _0.2 Mn _0.3 (OH) ₂ , Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ , Ni _0.7 Co _0.15 Mn _0.15 (OH) ₂ , Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ , Ni _1/3 Co _1/3 Mn _1/3 CO ₃ , Ni _0.5 One or more of Co _0.2 Mn _0.3 CO ₃ , Ni _0.6 Co _0.2 Mn _0.2 CO ₃ , Ni _0.7 Co _0.15 Mn _0.15 CO ₃ , Ni _0.8 Co _0.1 Mn _0.1 CO ₃ .

As a preference of the above technical solution, in step (1), the niobium source is selected from one or more of niobium oxide, niobium oxalate, and ammonium niobate oxalate hydrate.

As a preference of the above technical solution, in step (1), the lithium salt is selected from one or more of lithium hydroxide, lithium carbonate, lithium nitrate and lithium acetate.

As a preference of the above technical solution, in step (1), the rotational speed of the ball mill is 80-200 r/min.

As a preference of the above technical solution, in step (1), the ball milling time is 1-6 hours.

As a preference of the above technical solution, in step (2), the pre-calcination temperature is 300-800°C.

As a preference of the above technical solution, in step (2), the pre-burning time is 1-10 hours.

As a preference of the above technical solution, in step (3), the rotational speed of the ball mill is 80-200 r/min.

As a preference of the above technical solution, in step (3), the ball milling time is 1-6 hours.

As a preference of the above technical solution, in step (4), the calcination temperature is 600-1000°C.

As a preference of the above technical solution, in step (4), the calcination time is 6-20 hours.

As a preference of the above technical solution, in step (4), the sintering atmosphere is one of O ₂ , Ar, H ₂ , N ₂ , and air.

The niobium-doped nickel-cobalt lithium manganese oxide positive electrode material prepared by the invention has simple required devices, convenient operation and easy industrialization. Because the electrochemically inert Nb ⁵⁺ is doped in the nickel-cobalt-lithium-manganese-oxide cathode material, the stability of the bulk phase and surface structure of the nickel-cobalt-lithium manganate cathode material can be improved, and side reactions at the interface between the electrode material and the electrolyte can be reduced. . When it is applied to lithium-ion batteries, it significantly improves the performance of the battery, especially the cycle performance under high voltage, and prolongs the service life of the battery.

Description of drawings

Fig. 1 is the SEM picture of the material obtained in Example 1.

Fig. 2 is the graph of the electrochemical cycling performance of the material obtained in Example 1.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

Example 1

A preparation method of a doped nickel cobalt lithium manganese oxide positive electrode material, comprising the following steps:

(1) The nickel-cobalt-manganese precursors Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ were ball milled and mixed in a planetary ball mill. The molar ratio of Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ is 1:0.005:0.54. The ball milling speed was 150 r/min, and the ball milling time was 2 h;

(2) The obtained mixture was pre-fired in a muffle furnace at a sintering temperature of 600 °C and a sintering time of 7 h;

(3) Mix the pre-burned materials by ball milling in a planetary ball mill, the ball milling speed is 150 r/min, and the ball milling time is 2 hours;

(4) The obtained mixture was calcined in a high-temperature tubular atmosphere furnace to obtain the final product. The sintering temperature was 870°C, the sintering time was 15 h, and the sintering atmosphere was O ₂ . The chemical formula of the obtained product was Li(Ni _0.6 Co _0.2 Mn _0.2 ) _0.99 Nb _0.01 O ₂ .

Example 2

A preparation method of a doped nickel cobalt lithium manganese oxide positive electrode material, comprising the following steps:

(1) The nickel-cobalt-manganese precursors Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ were ball milled and mixed in a planetary ball mill. The molar ratio of Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ is 1:0.005:0.525. The ball milling speed was 150 r/min, and the ball milling time was 2 h;

(2) Pre-fire the obtained mixture in a muffle furnace, the sintering temperature is 500 degrees, and the sintering time is 6 h;

(3) Mix the pre-burned materials by ball milling in a planetary ball mill, the ball milling speed is 150 r/min, and the ball milling time is 2 hours;

(4) The obtained mixture is calcined in a high-temperature tubular atmosphere furnace to obtain the final product. The sintering temperature is 800 degrees, the sintering time is 15 h, and the sintering atmosphere is O ₂ . The chemical formula of the obtained product is Li(Ni _0.8 Co _0.1 Mn _0.1 ) _0.99 Nb _0.01 O ₂ .

Example 3

A preparation method of a doped nickel cobalt lithium manganese oxide positive electrode material, comprising the following steps:

(1) The nickel-cobalt-manganese precursors Ni _0.5 Co _0.2 Mn _0.3 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ were ball milled and mixed in a planetary ball mill. The molar ratio of Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ is 1:0.005:0.55. The ball milling speed was 150 r/min, and the ball milling time was 2 h;

(2) Pre-fire the obtained mixture in a muffle furnace, the sintering temperature is 600 degrees, and the sintering time is 7 h;

(3) Mix the pre-burned materials by ball milling in a planetary ball mill, the ball milling speed is 150 r/min, and the ball milling time is 2 hours;

(4) The obtained mixture is calcined in a high-temperature tubular atmosphere furnace to obtain the final product. The sintering temperature is 900 degrees, the sintering time is 12 h, and the sintering atmosphere is O ₂ . The chemical formula of the obtained product is Li(Ni _0.5 Co _0.2 Mn _0.3 ) _0.99 Nb _0.01 O ₂ .

Example 4

A preparation method of a doped nickel cobalt lithium manganese oxide positive electrode material, comprising the following steps:

(1) Mix Ni _0.33 Co _0.33 Mn _0.33 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ precursors in a planetary ball mill. The molar ratio of Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ , Nb ₂ O ₅ and Li ₂ CO ₃ is 1:0.005:0.55. The ball milling speed was 150 r/min, and the ball milling time was 2 h;

(2) Pre-fire the obtained mixture in a muffle furnace, the sintering temperature is 600 degrees, and the sintering time is 7 h;

(3) Mix the pre-burned materials by ball milling in a planetary ball mill, the ball milling speed is 150 r/min, and the ball milling time is 2 hours;

(4) The obtained mixture is calcined in a high-temperature tubular atmosphere furnace to obtain the final product. The sintering temperature is 950 degrees, the sintering time is 15 h, and the sintering atmosphere is air. The chemical formula of the obtained product is Li(Ni _0.33 Co _0.33 Mn _0.33 ) _0.99 Nb _0.01 O ₂ .

The effect of the embodiment of the present invention will be described below by testing the materials obtained in the embodiment.

Scanning electron microscope (SEM) test

The cathode material obtained in Example 1 was subjected to a scanning electron microscope (SEM) test, and the test instrument model was Hitachi S-4800 field emission scanning electron microscope.

From the SEM test results, it can be seen that the nickel-cobalt-lithium-manganese-oxide cathode material obtained in Example 1 is a secondary ball formed by the accumulation of primary particles, and the particle size of the ball is ~8 um.

Electrochemical Performance Evaluation

The cathode material obtained in Example 1 was used to form a CR2016 button battery, and the electrochemical performance was evaluated. The positive electrode material, conductive agent and binder are mixed according to the weight ratio of 8:1:1, and then coated on the aluminum foil current collector with a certain thickness. Using 1.0 mol/L LiPF ₆ /EC+DEC (volume ratio 1:1) as the electrolyte, Li sheet as the counter electrode, and American Cellgard-2400 polypropylene membrane as the diaphragm, it was assembled in a glove box filled with argon. Button batteries. Then the normal temperature (25°C) cycle life test of the prepared material was carried out on the LandCT2001A battery test system produced by Wuhan Jinnuo Electronics Co., Ltd. The voltage range is 3.0-4.5V. The first five charge and discharge cycles of the battery are pre-activated with a current density of 36mA/g (0.2C), and the subsequent cycles are charged and discharged with a current density of 180mA/g (1C).

It can be seen from the electrochemical performance test results that the product obtained in Example 1 has excellent cycle performance under high voltage. After activation at 0.2C, the discharge capacity of 1C in Example 1 was 177.6mAh/g, and after 4.5 V and 80 cycles, the specific discharge capacity of Example 1 was 163.9mAh/g. The capacity retention rate of the doped nickel-cobalt lithium manganate cathode material obtained in Example 1 was 92.3% (see FIG. 2 for details).

The specific embodiments of the present invention have been described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to this practice are also within the scope of the present invention. Therefore, equivalent changes and modifications made without departing from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims (10)

1. a kind of preparation method of doping type nickel-cobalt lithium manganate cathode material, it is characterised in that concretely comprise the following steps：

（1）By nickel cobalt manganese presoma, niobium source and the lithium salts ball milling mixing in planetary ball mill；

（2）The pre-burning in Muffle furnace by the mixture of gained；

（3）By the material after pre-burning, secondary ball milling mixes in planetary ball mill；

（4）The mixture of gained is calcined in high-temperature tubular atmosphere furnace and obtains final products.

2. preparation method according to claim 1, it is characterised in that step（1）Described in nickel cobalt manganese presoma, niobium Source, the mol ratio of lithium salts are 1.0:（ 0.002-0.1）:（0.5-1.1）.

3. preparation method according to claim 1 or 2, it is characterised in that step（1）Described in nickel cobalt manganese presoma be selected from Ni_1/3Co_1/3Mn_1/3(OH)₂, Ni_0.5Co_0.2Mn_0.3(OH)₂, Ni_0.6Co_0.2Mn_0.2(OH)₂, Ni_0.7Co_0.15Mn_0.15(OH)₂, Ni_0.8Co_0.1Mn_0.1(OH)₂, Ni_1/3Co_1/3Mn_1/3CO₃, Ni_0.5Co_0.2Mn_0.3CO₃, Ni_0.6Co_0.2Mn_0.2CO₃, Ni_0.7Co_0.15Mn_0.15CO₃, Ni_0.8Co_0.1Mn_0.1 CO₃, in one or more.

4. preparation method according to claim 3, it is characterised in that step（1）Described in niobium source be selected from niobium oxide, oxalic acid Niobium, the one or more in niobic acid ammonium oxalic acid salt hydrate.

5. according to the preparation method described in claim 1,2 or 4, it is characterised in that step（1）Described in lithium salts be selected from hydroxide Lithium, lithium carbonate, lithium nitrate, the one or more in lithium acetate.

6. preparation method according to claim 5, it is characterised in that step（1）Described in rotational speed of ball-mill be 80-200 r/ min；The Ball-milling Time is 1-6 hours.

7. according to the preparation method described in claim 1,2,4 or 6, it is characterised in that step（2）Described in calcined temperature be 300-800 DEG C, burn-in time is 1-10 hours.

8. preparation method according to claim 7, it is characterised in that step（3）Described in rotational speed of ball-mill be 80-200 r/ Min, Ball-milling Time are 1-6 hours.

9. according to the preparation method described in claim 1,2,4,6 or 8, it is characterised in that step（4）Described in calcining heat be 600-1000 DEG C, the calcination time is 6-20 hours.

10. preparation method according to claim 9, it is characterised in that step（4）Described in sintering atmosphere be O₂、Ar、H₂、 N₂, one kind in air.