CN112174222A - TiN-coated nickel-cobalt-manganese ternary positive electrode material and preparation method thereof - Google Patents

Abstract

The invention discloses a TiN-coated nickel-cobalt-manganese ternary cathode material and a preparation method thereof, belonging to the technical field of lithium ion battery preparation. A preparation method of TiN coated nickel-cobalt-manganese ternary cathode material comprises the processes of coprecipitation reaction, primary sintering, secondary sintering, jaw crushing, roller pair, crushing and sieving, and the method is simple and easy to realize, and is controllable and easy to operate on equipment and related conditions; the ternary cathode material used as the battery cathode material has good rate performance and excellent cycle performance, and makes up for the defects of the prior art.

Description

TiN-coated nickel-cobalt-manganese ternary positive electrode material and preparation method thereof

Technical Field

The invention belongs to the technical field of lithium ion battery preparation, and particularly relates to a TiN-coated nickel-cobalt-manganese ternary cathode material and a preparation method thereof.

Background

With the development of the concept of "rocking chair type battery" in the 80 s of the 20 th century, the development of the lithium ion battery has achieved breakthrough progress, and the lithium ion battery has been widely applied to portable electronic devices such as mobile phones, digital cameras, notebook computers and the like by virtue of the advantages of long cycle life, high energy density, no memory effect, rapid discharge, low self-discharge rate, wide working temperature range, safety, reliability and the like. With the rise of new technologies such as electric vehicles, smart grids and the like, lithium ion battery technologies have wider development prospects. As a secondary battery which develops most rapidly in the last 20 years, a lithium ion battery is called "the most promising chemical power source", and is a "green secondary battery in the 21 st century", which has been the focus of attention and research.

The most potential positive electrode material of the lithium ion battery at present is the non-ternary material. The nickel-cobalt-aluminum battery used by the famous electric automobile Tesla in the world is one of ternary materials. The ternary material is superior to other positive electrode materials in voltage and capacity. However, the high voltage can cause the decomposition of the electrolyte, and researches show that the oxidative decomposition of the electrolyte can form an SEI film on the surface of the anode material, the SEI film can seriously hinder the normal deintercalation of lithium ions, and with the increase of the cycle number, the available lithium is less and less, so that the capacity is seriously attenuated.

Researches show that the titanium nitrogen coating does not influence the shape and structure of the material, an amorphous TiN layer is formed on the surface of the anode material particles after the titanium nitrogen coating is subjected to the heat nitrogen treatment, and the high-conductivity coating not only can reduce the contact between the anode material and the electrolyte, but also can obviously enhance the conductivity of the anode material, and is beneficial to the improvement of the rate capability and the cycle performance of the battery material.

Disclosure of Invention

Based on the existing problems, the invention provides a TiN-coated nickel-cobalt-manganese ternary cathode material and a preparation method thereof, and the ternary cathode material has excellent rate capability and cycle performance; the preparation method is simple, and the used equipment and preparation conditions are controllable and easy to operate.

The solution of the invention for solving the technical problem is as follows:

a preparation method of TiN coated nickel-cobalt-manganese ternary cathode material comprises the following steps:

s1, introducing nitrogen into a reaction kettle to exhaust air in the kettle, simultaneously introducing a soluble mixed salt solution, a sodium hydroxide solution and ammonia water into the reaction kettle with a base solution, carrying out coprecipitation reaction, and aging, washing, drying and deironing a product after the reaction is finished to obtain a nickel-cobalt-manganese ternary precursor;

s2, mixing the dispersing agent, the nickel-cobalt-manganese ternary precursor and lithium hydroxide, carrying out ball milling for 2-3h, and then carrying out vacuum drying; under the condition of oxygen-enriched atmosphere, performing primary sintering on the dried powder to obtain a nickel-cobalt-manganese ternary positive electrode material;

s3, carrying out jaw crushing, roller pair crushing and sieving on the nickel-cobalt-manganese ternary positive electrode material obtained in the step S2;

s4, carrying out wet grinding and mixing on the sieved nickel-cobalt-manganese ternary positive electrode material, a titanium-containing compound and a nitrogen-containing compound, and carrying out vacuum drying; and under the condition of oxygen-enriched atmosphere, secondarily sintering the dried powder, and then crushing, rolling, crushing and sieving the powder to obtain the TiN-coated nickel-cobalt-manganese ternary cathode material.

Further, in step S1, the soluble mixed salt solution is a mixed solution of soluble nickel salt, cobalt salt, and manganese salt.

Further, in step S1, the conditions of the coprecipitation reaction are: the ammonia value in the reaction kettle is 5-6 g/L; the reaction temperature is 45-65 ℃, and the particle size is 3.5-4 μm.

Further, in step S1, the concentration of the sodium hydroxide solution is 4-6 mol/L.

Further, in step S2, the oxygen volume concentration of the oxygen-rich atmosphere is 99%; the primary sintering temperature is 750-900 ℃, and the heat preservation time is 10-35 h.

Specifically, in the steps S2 and S4, the dynamic rotary drying device is preferably used as the vacuum drying device, and includes a coulter vacuum dryer, a double-cone vacuum dryer, and a spray dryer; preferably, the dynamic rotary drying device is a double cone vacuum dryer.

Further, in step S3, the pair-roller nip gap: 0.1-0.5 mm; jet milling frequency: 20-60 Hz.

Further, in step S4, the titanium-containing compound is at least one of titanium dioxide and titanium isopropoxide, preferably titanium isopropoxide; the nitrogen-containing compound is one of melamine and urea, and melamine is preferred.

Further, in step S4, the oxygen volume concentration of the oxygen-rich atmosphere is 99%; the sintering temperature is 750-900 ℃, and the heat preservation time is 10-40 h.

Furthermore, the total mole number of the nickel ions, the cobalt ions and the manganese ions in the mixed solution is 1, and the total ion concentration is 1.6-2.0 mol/L.

Specifically, in step S2, the dispersant is water, ethanol, preferably ethanol; the molar ratio of nickel, cobalt and manganese in the nickel, cobalt and manganese ternary precursor and the lithium hydroxide is 1: 1.05.

a TiN-coated nickel-cobalt-manganese ternary cathode material obtained by the preparation method of any one of the preceding claims.

The invention has the beneficial effects that: the method for preparing the TiN-coated nickel-cobalt-manganese ternary cathode material is simple, convenient and fast, and is controllable and easy to operate on equipment and related conditions; the ternary cathode material used as the battery cathode material has good rate performance and excellent cycle performance, and makes up for the defects of the prior art.

Drawings

FIG. 1 is an SEM image of ternary Ni-Co-Mn positive electrode material prepared in example 1;

FIG. 2 is an XRD diffraction pattern of the ternary nickel-cobalt-manganese cathode material prepared in example 1;

FIG. 3 shows capacity retention rates of ternary nickel-cobalt-manganese cathode materials prepared in comparative example 1 and example 1 at different multiplying factors;

FIG. 4 is a graph of the cycle performance of the ternary nickel-cobalt-manganese cathode material prepared in example 1.

Detailed Description

The conception, specific structure, and technical effects of the present application will be described clearly and completely with reference to the following embodiments, so that the purpose, features, and effects of the present application can be fully understood. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all embodiments, and other embodiments obtained by those skilled in the art without inventive efforts based on the embodiments of the present application belong to the protection scope of the present application.

Comparative example 1

Preparing a nickel sulfate, cobalt sulfate and manganese sulfate mixed solution with the total ion concentration of 1.6mol/L according to the proportion of nickel, cobalt and manganese of 0.8:0.1: 0.1. And simultaneously introducing the mixed solution, 5mol/L sodium hydroxide solution and ammonia water into a reaction kettle filled with the base solution at the speed of 5L/h, 2L/h and 1.8L/h respectively. Controlling the ammonia value in the reaction kettle to be 5g/L, controlling the temperature to be 50 ℃, and controlling the pH value to stabilize the granularity to be 3.5 mu m. Aging, washing, drying, mixing, screening and deironing the feed liquid overflowing from the reaction kettle to obtain a precursor material Ni_0.8Co_0.1Mn_0.1(OH)₂。

465g of lithium hydroxide, 1000g of ternary precursor and 1000ml of ethanol are weighed, ball-milled, fully mixed and dried in a double-cone vacuum dryer. Finally, sintering at 850 ℃ for 10h under the atmosphere of oxygen volume concentration of 99%, cooling, crushing by jaw, crushing by roller pair, and sieving to obtain the ternary cathode material LiNi_0.8Co_0.1Mn_0.1O₂. The distance between the double-roller crack is 0.5 mm; the jet milling frequency was 60 Hz.

The prepared ternary cathode material is used as a cathode active substance, a metal lithium sheet is used as a cathode, lmo1L-1LiPF6 and EC/DMC (volume ratio l: l) are used as electrolytes, and the lithium ion button battery is prepared. And carrying out rate test on the assembled button cell (3.0-4.3V, 0.1C/0.5C/2C/5C/10C). Through tests, the capacity retention rate of the uncoated positive electrode material is 90.3% after the positive electrode material is cycled for 100 circles at a multiplying power of 1C, and the capacity retention rate of the uncoated positive electrode material is 56% at a multiplying power of 10C.

Example 1

Preparing a TiN coated nickel-cobalt-manganese ternary cathode material:

s1, introducing nitrogen into a reaction kettle to exhaust air in the reaction kettle, and preparing a nickel sulfate, cobalt sulfate and manganese sulfate mixed solution with the total ion concentration of 1.6mol/L according to the proportion of nickel, cobalt and manganese in the reaction kettle of 0.8:0.1: 0.1. And simultaneously introducing the mixed solution, 5mol/L sodium hydroxide solution and ammonia water into a reaction kettle filled with the base solution at the speed of 5L/h, 2L/h and 1.8L/h respectively. Controlling the ammonia value in the reaction kettle to be 5g/L, controlling the temperature to be 50 ℃, and controlling the pH value to stabilize the granularity to be 3.5 mu m. Aging, washing, drying, mixing, screening and deironing the feed liquid overflowing from the reaction kettle to obtain a nickel-cobalt-manganese ternary precursor material Ni_0.8Co_0.1Mn_0.1(OH)₂。

S2, weighing 465g of lithium hydroxide, 1000g of ternary precursor and 1000ml of ethanol, mixing and ball-milling for 2 hours, fully mixing, and putting the slurry into a double-cone vacuum dryer for drying. Finally, primary sintering is carried out for 10h at 850 ℃ under the atmosphere of oxygen volume concentration of 99 percent;

s3, cooling, crushing by a jaw, carrying out double-roll crushing, and sieving to obtain the nickel-cobalt-manganese ternary positive electrode material LiNi_0.8Co_0.1MnO₂(ii) a The distance between the double-roller crack is 0.3 mm; the jet milling frequency is 45 Hz;

s4, weighing 1000g of ternary positive electrode material, 46.55g of titanium isopropoxide and 3.45g of melamine, carrying out wet grinding and mixing, and then drying under a vacuum condition; then sintering the dried powder for 20h at 850 ℃ under the oxygen volume concentration of 99 percent, and then crushing, rolling, crushing and sieving to obtain TiN-coated nickel-cobalt-manganese ternary positive electrode material LiNi_0.8Co_0.1Mn_0.1O₂(ii) a The distance between the double-roller crack is 0.3 mm; the jet milling frequency was 45 Hz.

The application of the TiN coated nickel-cobalt-manganese ternary cathode material comprises the following steps:

the lithium ion button battery is prepared by taking a TiN-coated nickel-cobalt-manganese ternary positive electrode material as a positive electrode active substance, a metal lithium sheet as a negative electrode and lmo1L-1LiPF6 and EC/DMC (volume ratio l: l) as electrolytes. The assembled button cell was tested for rate (3.0-4.3V, 0.1C/0.5C/2C/5C/10C) and 100 cycles at 1C rate. Through tests, the capacity retention rate of the TiN-coated ternary cathode material is 98.5% under the condition of 1C multiplying power of 100 cycles, and the capacity retention rate is 71% under the condition of 10C.

FIG. 1 is an SEM image of ternary Ni-Co-Mn positive electrode material prepared in example 1; FIG. 2 is an XRD diffraction pattern of the ternary nickel-cobalt-manganese cathode material prepared in example 1; FIG. 3 shows capacity retention rates of ternary nickel-cobalt-manganese cathode materials prepared in comparative example 1 and example 1 at different multiplying factors, wherein NCM is the ternary nickel-cobalt-manganese cathode material obtained in comparative example 1, and NCM-TiN is the ternary nickel-cobalt-manganese cathode material obtained in example 1; FIG. 4 is a graph of the cycle performance of the ternary nickel-cobalt-manganese cathode material prepared in example 1.

Example 2

Preparing a TiN coated nickel-cobalt-manganese ternary cathode material:

s1, introducing nitrogen into a reaction kettle to exhaust air in the reaction kettle, and preparing a nickel sulfate, cobalt sulfate and manganese sulfate mixed solution with the total ion concentration of 1.8mol/L according to the proportion of nickel, cobalt and manganese in the reaction kettle of 0.8:0.1: 0.1. And simultaneously introducing the mixed solution, 5mol/L sodium hydroxide solution and ammonia water into a reaction kettle filled with the base solution at the speed of 5L/h, 2L/h and 1.8L/h respectively. Controlling the ammonia value in the reaction kettle to be 5.5g/L, controlling the temperature to be 45 ℃, and controlling the pH value to stabilize the particle size to be 3.8 mu m. Aging, washing, drying, mixing, screening and deironing the feed liquid overflowing from the reaction kettle to obtain a nickel-cobalt-manganese ternary precursor material Ni_0.8Co_0.1Mn_0.1(OH)₂。

S2, weighing 465g of lithium hydroxide, 1000g of ternary precursor and 1000ml of ethanol, mixing, ball-milling for 2.5h, fully mixing, and drying the slurry in a double-cone vacuum dryer. Finally, sintering for 35h at 900 ℃ under the atmosphere with the volume concentration of oxygen of 99%;

s3, cooling, crushing by a jaw, carrying out double-roll crushing, and sieving to obtain the nickel-cobalt-manganese ternary positive electrode material LiNi_0.8Co_0.1MnO₂(ii) a The distance between the double-roller crack is 0.1 mm; the jet milling frequency is 20 Hz;

s4, weighing 1000g of ternary positive electrode material, 65.17g of titanium isopropoxide and 4.83g of melamine, wet-milling and mixing, and then drying under a vacuum condition; then carrying out secondary sintering on the dried powder at 900 ℃ for 10h with the volume concentration of oxygen of 99 percent, and then carrying out jaw crushing, roller pair crushing and sieving to obtain the TiN-coated nickel-cobalt-manganese ternary cathode material LiNi_0.8Co_0.1Mn_0.1O₂(ii) a The distance between the double-roller crack is 0.5 mm; the jet milling frequency was 60 Hz.

The application of the TiN coated nickel-cobalt-manganese ternary cathode material comprises the following steps:

the lithium ion button battery is prepared by taking a TiN-coated nickel-cobalt-manganese ternary positive electrode material as a positive electrode active substance, a metal lithium sheet as a negative electrode and lmo1L-1LiPF6 and EC/DMC (volume ratio l: l) as electrolytes. The assembled button cell was tested for rate (3.0-4.3V, 0.1C/0.5C/2C/5C/10C) and 100 cycles at 1C rate. Through tests, the capacity retention rate of the TiN-coated ternary cathode material is 94.7% under the condition of 1C multiplying power of 100 cycles, and the capacity retention rate is 65% under the condition of 10C.

Example 3

Preparing a TiN coated nickel-cobalt-manganese ternary cathode material:

s1, introducing nitrogen into a reaction kettle to exhaust air in the reaction kettle, and preparing a nickel sulfate, cobalt sulfate and manganese sulfate mixed solution with the total ion concentration of 2.0mol/L according to the proportion of nickel, cobalt and manganese in the reaction kettle of 0.8:0.1: 0.1. And simultaneously introducing the mixed solution, 5mol/L sodium hydroxide solution and ammonia water into a reaction kettle filled with the base solution at the speed of 5L/h, 2L/h and 1.8L/h respectively. The ammonia value in the reaction kettle is controlled to be 6g/L, the temperature is 65 ℃, and the pH value is controlled to stabilize the particle size to be 4 mu m. Aging, washing, drying, mixing, screening and deironing the feed liquid overflowing from the reaction kettle to obtain a nickel-cobalt-manganese ternary precursor material Ni_0.8Co_0.1Mn_0.1(OH)₂。

S2, weighing 465g of lithium hydroxide, 1000g of ternary precursor and 1000ml of ethanol, mixing, ball-milling for 3 hours, fully mixing, and drying the slurry in a double-cone vacuum dryer. Finally, primary sintering is carried out for 20h at 750 ℃ under the atmosphere with the volume concentration of oxygen of 99 percent;

s3, cooling, crushing by a jaw, carrying out double-roll crushing, and sieving to obtain the nickel-cobalt-manganese ternary positive electrode material LiNi_0.8Co_0.1MnO₂(ii) a The distance between the double-roller crack is 0.5 mm; the jet milling frequency is 60 Hz;

s4, weighing 1000g of ternary positive electrode material, 93.1g of titanium isopropoxide and 6.9g of melamine, wet-milling and mixing, and then drying under a vacuum condition; then carrying out secondary sintering on the dried powder at the temperature of 750 ℃ for 10h under the oxygen volume concentration of 99 percent, and then carrying out jaw crushing, roller pair crushing and sieving to obtain the TiN-coated nickel-cobalt-manganese ternary positive electrode material LiNi_0.8Co_0.1Mn_0.1O₂(ii) a The distance between the double-roller crack is 0.5 mm; the jet milling frequency was 60 Hz.

The application of the TiN coated nickel-cobalt-manganese ternary cathode material comprises the following steps:

the lithium ion button battery is prepared by taking a TiN-coated nickel-cobalt-manganese ternary positive electrode material as a positive electrode active substance, a metal lithium sheet as a negative electrode and lmo1L-1LiPF6 and EC/DMC (volume ratio l: l) as electrolytes. The assembled button cell was tested for rate (3.0-4.3V, 0.1C/0.5C/2C/5C/10C) and 100 cycles at 1C rate. Through tests, the capacity retention rate of the TiN-coated ternary cathode material is 85.2% under the condition of circulation of 100 circles at the multiplying power of 1C, and the capacity retention rate is 51.3% under the condition of 10C.

While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited to the details of the embodiments, but is capable of various modifications and substitutions without departing from the spirit of the invention.

Claims (10)

1. A preparation method of TiN-coated nickel-cobalt-manganese ternary cathode material is characterized by comprising the following steps:

s1, introducing nitrogen into a reaction kettle to exhaust air in the kettle, simultaneously introducing a soluble mixed salt solution, a sodium hydroxide solution and ammonia water into the reaction kettle with a base solution, carrying out coprecipitation reaction, and aging, washing, drying and deironing a product after the reaction is finished to obtain a nickel-cobalt-manganese ternary precursor;

s2, mixing the dispersing agent, the nickel-cobalt-manganese ternary precursor and lithium hydroxide, carrying out ball milling for 2-3h, and then carrying out vacuum drying; under the condition of oxygen-enriched atmosphere, performing primary sintering on the dried powder to obtain a nickel-cobalt-manganese ternary positive electrode material;

s3, carrying out jaw crushing, roller pair crushing and sieving on the nickel-cobalt-manganese ternary positive electrode material obtained in the step S2;

s4, carrying out wet grinding and mixing on the sieved nickel-cobalt-manganese ternary positive electrode material, a titanium-containing compound and a nitrogen-containing compound, and carrying out vacuum drying; and under the condition of oxygen-enriched atmosphere, secondarily sintering the dried powder, and then crushing, rolling, crushing and sieving the powder to obtain the TiN-coated nickel-cobalt-manganese ternary cathode material.

2. The method of claim 1, wherein in step S1, the soluble mixed salt solution is a mixed solution of soluble nickel salt, cobalt salt, and manganese salt.

3. The method according to claim 1, wherein in step S1, the co-precipitation reaction conditions are as follows: the ammonia value in the reaction kettle is 5-6 g/L; the reaction temperature is 45-65 ℃, and the particle size is 3.5-4 μm.

4. The method of claim 1, wherein in step S1, the concentration of the sodium hydroxide solution is 4-6 mol/L.

5. The method according to claim 1, wherein in step S2, the oxygen-rich atmosphere has an oxygen volume concentration of 99%; the primary sintering temperature is 750-900 ℃, and the heat preservation time is 10-35 h.

6. The method of claim 1, wherein in step S3, the roll gap: 0.1-0.5 mm; jet milling frequency: 20-60 Hz.

7. The method of claim 1, wherein in step S4, the titanium-containing compound is at least one of titanium dioxide and titanium isopropoxide, preferably titanium isopropoxide; the nitrogen-containing compound is one of melamine and urea, and melamine is preferred.

8. The method according to claim 1, wherein in step S4, the oxygen-rich atmosphere has an oxygen volume concentration of 99%; the sintering temperature is 750-900 ℃, and the heat preservation time is 10-40 h.

9. The method according to claim 2, wherein the total mole number of the nickel ions, the cobalt ions and the manganese ions in the mixed solution is 1, and the total ion concentration is 1.6-2.0 mol/L.

10. A TiN-coated nickel-cobalt-manganese ternary positive electrode material, characterized by being obtained by the preparation method of any one of claims 1 to 9.

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