CN108682822A - A kind of nickelic ternary material of long circulation life and preparation method thereof - Google Patents

Abstract

The invention discloses nickelic tertiary cathode materials of a kind of long circulation life and preparation method thereof, are coated to nickelic tertiary cathode material surface in such a way that wet method cladding combines mechanical fusion：Nickelic tertiary cathode material is uniformly mixed in a solvent with pre-coated object, removes solvent, mechanical fusion is carried out after calcining under oxygen, obtains the nickelic tertiary cathode material that oxide uniformly coats.The method of the present invention is simple, and material surface is evenly coated and strong adhesive force, has good protective effect to nickelic tertiary cathode material, therefore storage performance, processing performance are good, has higher specific capacity and cycle life.

Description

A kind of high-nickel ternary material with long cycle life and preparation method thereof

technical field

The invention relates to the technical field of cathode materials for lithium ion batteries, in particular to a high-nickel ternary material with long cycle life and a preparation method thereof.

Background technique

There are many technical routes such as lithium iron phosphate, ternary materials and lithium manganate in the cathode material of electric vehicle power lithium battery. These cathode materials have their own characteristics and advantages in terms of energy density, cost, safety, thermal stability and cycle life, leading to diversification of the technical route of cathode materials for power lithium batteries. In comparison, the theoretical energy density of lithium manganese oxide batteries and lithium iron phosphate batteries is relatively low. Therefore, in recent years, power batteries with three positive electrode materials with higher energy densities have been generally favored by the market. At present, the ternary cathode material with the largest circulation in the market is the 532 type, followed by the 111 type. Under the voltage of 4.2V, the gram capacity of the 111-type material is close to 160mAh/g, and that of the 532-type material is close to 170mAh/g. As high-energy-density power lithium batteries are increasingly becoming the mainstream of future development, domestic and foreign cathode material manufacturers have begun to research new cathode materials with higher specific energy.

Compared with traditional ternary cathode materials (type 111 and 523), high-nickel ternary cathode materials (lithium nickel cobalt aluminate and 622, 71515, 811 type nickel cobalt lithium manganese oxide) have higher specific capacity, but due to Its nickel content is high, the amount of residual alkali on the surface of the material is large, it is easy to absorb water, it is easy to decompose during the charging and discharging process of the battery, and a disproportionation reaction occurs, resulting in a decrease in the battery cycle performance; It is difficult to homogenize the material, which makes the battery processing performance worse. To solve this problem, the general solution is to coat the surface of the material with nano-oxide, but the traditional coating method is difficult to achieve uniform coating on the surface, and the adhesion between the coating and the body is small, and subsequent processing may cause The coating falls off, so no effective protection can be formed.

Contents of the invention

Aiming at the problems of high residual alkali value on the surface of high-nickel ternary positive electrode materials, difficult processing, poor cycle performance, and easy gas production, the present invention provides a high-nickel ternary material with a long cycle life and a preparation method thereof, without reducing the Under the condition of the first charge and discharge capacity of the material, the cycle stability of the nickel ternary cathode material can be effectively improved.

To achieve the above object, the present invention adopts the following technical solutions:

A method for preparing a high-nickel ternary material with long cycle life, comprising the following steps:

Step 1: Mix the high-nickel ternary positive electrode material and the pre-coating material in a solvent evenly, remove the solvent, and obtain the high-nickel ternary positive electrode material wrapped by the pre-coating material;

Step 2: calcining the high-nickel ternary positive electrode material wrapped by the pre-coating material under oxygen to obtain the high-nickel ternary positive electrode material coated with oxide;

Step 3: mechanically fusing the oxide-coated high-nickel ternary cathode material to obtain a high-nickel ternary cathode material uniformly coated with oxide.

Further, the high-nickel ternary positive electrode material is nickel-cobalt lithium aluminate, 622-type nickel-cobalt lithium manganese oxide, 71515-type nickel-cobalt lithium manganate or 811-type nickel-cobalt lithium manganese oxide.

Further, the pre-coating is one or more of aluminum isopropoxide, aluminum nitrate, aluminum sulfate, aluminum acetate, aluminum chloride, tetrabutyl titanate, titanium isopropoxide and titanium tetrachloride kind.

Further, the solvent is one or more of ethanol, ethylene glycol, isopropanol, ethylene glycol methyl ether and ethylene glycol ether.

Further, in the first step, the mass ratio of the pre-coating material to the high-nickel ternary positive electrode material is (0.001-0.05):1.

Further, in the second step, the calcination temperature is 300-750° C., and the calcination time is 2-10 h.

Further, the mechanical fusion in the step 3 is specifically mechanical stirring, the stirring speed is 2000-6000 rpm, and the stirring time is 2-15 min.

A high-nickel ternary material with long cycle life is prepared by the above-mentioned method.

Compared with the prior art, the present invention has the following beneficial technical effects:

The method of the present invention undergoes pre-coating-sintering-mechanical fusion, the surface coating is more uniform, the generation of lithium hydroxide and lithium carbonate is avoided, and the loss of active lithium ions is reduced; the surface coating is firmer, and coatings caused by subsequent processing are avoided Falling off; the coated material has good thermal stability and is not sensitive to moisture. It can prevent the surface of the positive electrode material from being eroded by the electrolyte at room temperature, even high temperature and high voltage, and improve the cycle life of the material.

Description of drawings

Fig. 1 is the scanning electron microscope picture of the nickel cobalt aluminate lithium that aluminum nitrate wraps in embodiment 4;

Fig. 2 is the scanning electron microscope picture of the nickel-cobalt-aluminate lithium that aluminum oxide evenly coats in embodiment 4;

FIG. 3 is a cycle performance curve of a coin half-cell assembled with nickel-cobalt-lithium aluminate uniformly coated with alumina in Example 4. FIG.

Detailed ways

The present invention is described in further detail below:

A method for preparing a high-nickel ternary cathode material with long cycle life, comprising the following steps:

1) Mix the high-nickel ternary positive electrode material and the pre-coating evenly in a solvent, remove the solvent, and obtain the high-nickel ternary positive electrode material wrapped by the pre-coating; the high-nickel ternary positive electrode material includes nickel-cobalt-aluminum Lithium oxide, 622 type nickel cobalt lithium manganate, 71515 type nickel cobalt lithium manganate, 811 type nickel cobalt lithium manganate, the pre-coating includes aluminum isopropoxide, aluminum nitrate, aluminum sulfate, aluminum acetate, chlorine One or more of aluminum chloride, tetrabutyl titanate, titanium isopropoxide, titanium tetrachloride; the solvent is ethanol, ethylene glycol, isopropanol, ethylene glycol methyl ether, ethylene glycol ether One or more, and the mass ratio of the pre-coating material to the high-nickel ternary positive electrode material is (0.001-0.05): 1; the method of removing the solvent includes stirring, heating, evaporating to dryness, and spray drying;

2) Calcining the high-nickel ternary positive electrode material wrapped by the pre-coating material under oxygen, the calcination temperature is 300-750°C, and the calcination time is 2-10h, to obtain the oxide-coated high-nickel ternary positive electrode material;

3) The material obtained in step 2) is mechanically fused at a rotational speed of 2000-6000 rpm for 2-15 minutes to obtain a high-nickel ternary positive electrode material evenly coated with oxides.

Below in conjunction with embodiment the present invention is described in further detail:

Example 1

1) Mix the mixture of 622-type nickel-cobalt lithium manganate and aluminum isopropoxide and titanium isopropoxide in ethanol evenly, the mass ratio of the mixture of aluminum isopropoxide and titanium isopropoxide to 622-type nickel-cobalt lithium manganate 0.001:1, stirred, heated and evaporated to dryness to obtain 622-type nickel cobalt lithium manganese oxide wrapped in aluminum isopropoxide;

2) Calcining the 622-type nickel-cobalt-lithium manganese oxide wrapped with aluminum isopropoxide at 750°C for 2 hours under oxygen to obtain the 622-type nickel-cobalt-lithium manganate coated with alumina;

3) The material obtained in step 2) was mechanically fused for 2 minutes at a rotational speed of 6000 rpm to obtain 622-type nickel-cobalt lithium manganese oxide uniformly coated with alumina.

Under the condition that other conditions remain unchanged, the solvent can also be ethylene glycol methyl ether, ethylene glycol ethyl ether or a mixture of the two.

Example 2

1) Mix 811-type nickel-cobalt lithium manganate and aluminum isopropoxide in isopropanol evenly, the mass ratio of aluminum isopropoxide to 811-type nickel-cobalt lithium manganate is 0.05:1, stir, heat and evaporate to dryness to obtain isopropoxide 811 type nickel cobalt lithium manganese oxide wrapped in aluminum propoxide;

2) Calcining the 811-type nickel-cobalt-lithium manganese oxide wrapped with aluminum isopropoxide at 300°C for 10 hours under oxygen to obtain the 811-type nickel-cobalt-lithium manganate coated with alumina;

3) The material obtained in step 2) was mechanically fused for 15 minutes at a rotational speed of 2000 rpm to obtain 811-type nickel-cobalt lithium manganese oxide uniformly coated with alumina.

Example 3

1) Mix 71515-type nickel-cobalt lithium manganate and tetrabutyl titanate in ethylene glycol evenly, the mass ratio of tetrabutyl titanate to 71515-type nickel-cobalt lithium manganate is 0.01:1, after spray drying, get 71515 nickel cobalt lithium manganese oxide coated with tetrabutyl titanate;

2) Calcining 71515-type nickel-cobalt-lithium manganese oxide coated with tetrabutyl titanate at 500°C under oxygen for 5 hours to obtain titanium oxide-coated 71515-type nickel-cobalt-lithium manganese oxide;

3) The material obtained in step 2) was mechanically fused for 10 minutes at a rotational speed of 4000 rpm to obtain 811-type nickel-cobalt lithium manganese oxide uniformly coated with alumina.

Under the condition that other conditions remain unchanged, the pre-coating material can also be aluminum sulfate, aluminum acetate, aluminum chloride, titanium isopropoxide, titanium tetrachloride.

Example 4

1) Mix lithium nickel cobalt aluminate and aluminum nitrate in ethanol evenly, the mass ratio of aluminum nitrate and lithium nickel cobalt aluminate is 0.002:1, after spray drying, obtain lithium nickel cobalt aluminate wrapped in aluminum nitrate;

2) calcining lithium nickel cobalt aluminate coated with aluminum nitrate at 650° C. for 3 hours under oxygen to obtain lithium nickel cobalt aluminate coated with alumina;

3) The material obtained in step 2) was mechanically fused for 5 minutes at a rotational speed of 5000 rpm to obtain lithium nickel cobalt aluminate evenly coated with alumina.

The material finally obtained in Example 4 was mixed with a conductive agent and a binder, coated, prepared into pole pieces, and assembled with a button half-cell, and the electrochemical performance of the material was evaluated. The results are shown in FIG. 3 .

Figure 2 is the material obtained after mechanical fusion in Figure 1. It can be seen that the coating is dispersed on the surface before mechanical fusion, and the particle adhesion phenomenon is obvious after mechanical fusion, and no coating is dispersed on the particle surface, indicating that after mechanical fusion The coating of the material is more uniform and firmer. It can be seen from Figure 3 that the cycle performance of the coated material is better, and the cycle capacity has no attenuation for 40 cycles.

Claims (8)

1. a kind of preparation method of the nickelic ternary material of long circulation life, which is characterized in that include the following steps：

Step 1：Nickelic tertiary cathode material is uniformly mixed in a solvent with pre-coated object, solvent is removed, obtains pre-coated object The nickelic tertiary cathode material of package；

Step 2：The nickelic tertiary cathode material that pre-coated object wraps up is calcined under oxygen, obtains the nickelic of oxide cladding Tertiary cathode material；

Step 3：The nickelic tertiary cathode material of oxide cladding is subjected to mechanical fusion, obtains the height that oxide uniformly coats Nickel tertiary cathode material.

2. a kind of preparation method of the nickelic ternary material of long circulation life according to claim 1, which is characterized in that institute The nickelic tertiary cathode material stated is nickel cobalt lithium aluminate, 622 type nickle cobalt lithium manganates, 71515 type nickle cobalt lithium manganates or 811 type nickel cobalts LiMn2O4.

3. a kind of preparation method of the nickelic ternary material of long circulation life according to claim 1, which is characterized in that institute The pre-coated object stated is aluminium isopropoxide, aluminum nitrate, aluminum sulfate, aluminum acetate, aluminium chloride, butyl titanate, isopropyl titanate and tetrachloro Change one or more in titanium.

4. a kind of preparation method of the nickelic ternary material of long circulation life according to claim 1, which is characterized in that institute It is one or more in ethyl alcohol, ethylene glycol, isopropanol, ethylene glycol monomethyl ether and ethylene glycol ethyl ether to state solvent.

5. a kind of preparation method of the nickelic ternary material of long circulation life according to claim 1, which is characterized in that institute It is (0.001-0.05) to state the mass ratio of pre-coated object and nickelic tertiary cathode material in step 1：1.

6. a kind of preparation method of the nickelic ternary material of long circulation life according to claim 1, which is characterized in that institute It is 300-750 DEG C to state calcination temperature in step 2, calcination time 2-10h.

7. a kind of preparation method of the nickelic ternary material of long circulation life according to claim 1, which is characterized in that institute It is specially mechanical agitation, speed of agitator 2000-6000rpm, time 2-15min to state mechanical fusion in step 3.

8. a kind of nickelic ternary material of long circulation life, which is characterized in that using any one of claim 1-9 the method systems It is standby to obtain.