Preparation method of lithium nickel manganese oxide

Abstract

The invention discloses a preparation method of lithium nickel manganese oxide, and relates to the technical field of synthesis of inorganic non-metallic materials. The method comprises the following steps: preparing an aqueous dispersion of a nickel source, a manganese source and a lithium source; placing the dispersion liquid in a ball-milling tank, adding zirconium dioxide ball-milling beads, and placing the ball-milling tank in a planetary ball mill for operation; taking out the ball-milled mixed solution, keeping mechanical dispersion and heating, continuously dropwise adding an emulsifier into the mixed solution in the process, keeping the temperature, and dispersing until moisture is completely evaporated to obtain nickel-manganese-lithium precursor powder; after the precursor powder is subjected to heat treatment, a lithium nickel manganese oxide product is obtained, the crystal structure is a spinel structure, and the microstructure is spherical particles observed by a scanning electron microscope; the method disclosed by the invention is relatively low in cost, simple to operate and easy to industrialize, and the prepared lithium nickel manganese oxide product has relatively small and uniform particle size, relatively high tap density, good stability and excellent battery performance.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic non-metallic material synthesis, in particular to a method for preparing lithium nickel manganese oxide. Background Art

[0002] Since its commercialization, lithium-ion battery technology has rapidly become the mainstream energy supply technology in fields such as electric vehicles and portable electronic devices due to its excellent overall performance. Its core advantages mainly include high energy density, long cycle life, low self-discharge rate, high operating voltage, continuously improving fast charging performance, and relative environmental protection.

[0003] Cathode materials are a core component of lithium-ion batteries, and their properties play a crucial role in the battery's overall performance. The number of lithium ions that can be intercalated and deintercalated and the redox potential relative to lithium metal determine the theoretical specific capacity and operating voltage. The material's internal crystal structure (channel size and dimensions) influences the lithium-ion diffusion rate. The material's inherent conductivity influences the electron transport rate within the battery. Smaller, more uniform cathode material particles can effectively shorten the ion-electron transport path, facilitating battery rate performance. The material's structural and interfacial stability influences the battery's long-term cycling stability. Furthermore, the safety, low-temperature performance, and cost of lithium-ion batteries are also significantly influenced by the cathode material. Current research focuses on improving these core properties. Researchers are continuously optimizing cathode materials, weighing these factors. Low-cost lithium nickel manganese oxide (LiMnO) materials are attracting attention due to their high energy density potential from their high operating voltage, excellent power performance, and the cost and resource advantages of being cobalt-free. This makes them a strong contender for high-power, high-energy-density, and cost-effective applications.

[0004] The preparation methods of high-pressure spinel lithium nickel manganese oxide include solid-phase method, co-precipitation method, sol-gel method, combustion method, etc. The advantage of the solid-phase method is that it has low equipment requirements (such as rotary kiln), is suitable for large-scale production, raw materials are easily available, and the cost is relatively controllable. However, its disadvantage is poor mixing uniformity, which often leads to limited gram capacity and cycle life performance. Patent CN107302083A discloses a solid-phase reaction preparation method for lithium nickel manganese oxide positive electrode material. The lithium nickel manganese oxide positive electrode material prepared by this invention has no impurity phase, a complete spinel structure, is not easy to agglomerate, and has a high capacity level, but its cycle performance is average. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing lithium nickel manganese oxide to solve the problems of poor product particle uniformity and limited cycle performance in the existing solid-phase method for preparing high-pressure spinel lithium nickel manganese oxide.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing lithium nickel manganese oxide, comprising the following specific contents:

[0007] S1 prepares aqueous dispersions of nickel source, manganese source and lithium source;

[0008] S2: placing the dispersion in a ball mill, adding zirconium dioxide ball milling beads, and running the ball mill in a planetary ball mill;

[0009] After the mixed solution is taken out from the ball mill in S3, it is kept mechanically dispersed and heated. During the process, an emulsifier is continuously added to the mixed solution and then kept warm. It is dispersed until the water is completely evaporated to obtain nickel-manganese-lithium precursor powder;

[0010] After heat treatment of the S4 precursor powder, lithium nickel manganese oxide product is obtained, whose crystal structure is spinel configuration, and the microstructure is spherical particles observed by scanning electron microscopy.

[0011] Preferably, in S1, the nickel source is one or more of nickel carbonate, nickel oxalate, and nickel hydroxide, the manganese source is one or more of manganese tetraoxide, manganese carbonate, and manganese oxalate, and the lithium source is lithium carbonate and / or lithium hydroxide.

[0012] More preferably in the above preferred embodiment, the molar ratio of nickel and manganese elements in the aqueous dispersion is 1:3, the molar ratio of the sum of nickel and manganese atoms to lithium atoms is 2:1.1, and the mass ratio of solid phase powder to water in the aqueous dispersion is 1:1.5-2.

[0013] Preferably, in S2, the sizes of zirconium dioxide ball milling beads are 4 mm and 6 mm, and the mass ratio is 2:1, the mass ratio of solid phase powder to ball milling beads is 1:2-3, the ball mill speed is 300-500 rpm, and the ball milling time is 2-4 h.

[0014] Preferably, in S3, the emulsifier is one or more of monostearate, zinc stearate, and cetyltrimethylammonium bromide, and the amount of the emulsifier is controlled so that the mass ratio of water to emulsifier in the mixed solution is 1:0.015-0.03.

[0015] Preferably, in S3, the mechanical dispersion speed is 200-300 rpm, and the temperature of the mixed liquid during the insulation process is 50-60°C.

[0016] Preferably, in S4, the heat treatment temperature is 800-1000° C., the treatment time is 8-12 h, and the heat treatment atmosphere is air.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The preparation method of lithium nickel manganese oxide uses solid-phase ball milling as the basic scheme for one-step solid-phase mixing of nickel source, manganese source and lithium source, and uses an emulsifier to homogenize the phase state of the mixing process during the drying process. After drying, a nickel manganese lithium precursor is obtained, and the product is obtained after heat treatment. The advantage of emulsifier molecular coating is that on the one hand, it can effectively inhibit the segregation of lithium carbonate, and on the other hand, it can regulate the agglomerate structure after secondary agglomeration of low-sized powders, and inhibit irreversible sintering caused by capillary force during the drying process, effectively improving the uniformity of the powder product particles. The emulsifier molecules can also adjust the surface charge of the particles and reduce electrostatic force.

[0019] 2. The preparation method of lithium nickel manganese oxide can effectively improve the sphericity of lithium nickel manganese oxide products, regulate the secondary particle size and surface morphology, and the prepared lithium nickel manganese oxide products have relatively small and uniform particle size, high tap density, good stability and excellent battery performance. In addition, the process method is low in cost, simple to operate, and easy to scale up industrially. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 These are microscopic morphology images of the lithium nickel manganese oxide products in a) Example 1 and b) Comparative Example 1 of the present invention, taken using a transmission electron microscope (SEM).

[0021] Figure 2 This is a spectrum obtained by using X-ray diffraction spectroscopy (XRD) testing of the lithium nickel manganese oxide product in Example 1 of the present invention.

[0022] Figure 3 1 C charge-discharge curve of the lithium nickel manganese oxide sample of Example 1 of the present invention. DETAILED DESCRIPTION

[0023] A method for preparing lithium nickel manganese oxide, comprising the following specific contents:

[0024] S1 prepares aqueous dispersions of nickel source, manganese source and lithium source;

[0025] S2: placing the dispersion in a ball mill, adding zirconium dioxide ball milling beads, and running the ball mill in a planetary ball mill;

[0026] After the mixed solution is taken out from the ball mill in S3, it is kept mechanically dispersed and heated. During the process, an emulsifier is continuously added to the mixed solution and then kept warm. It is dispersed until the water is completely evaporated to obtain nickel-manganese-lithium precursor powder;

[0027] After heat treatment of the S4 precursor powder, lithium nickel manganese oxide product is obtained, whose crystal structure is spinel configuration, and the microstructure is spherical particles observed by scanning electron microscopy.

[0028] Preferably, in S1, the nickel source is one or more of nickel carbonate, nickel oxalate, and nickel hydroxide, the manganese source is one or more of manganese tetraoxide, manganese carbonate, and manganese oxalate, and the lithium source is lithium carbonate and / or lithium hydroxide.

[0029] More preferably in the above preferred embodiment, the molar ratio of nickel and manganese elements in the aqueous dispersion is 1:3, the molar ratio of the sum of nickel and manganese atoms to lithium atoms is 2:1.1, and the mass ratio of solid phase powder to water in the aqueous dispersion is 1:1.5-2.

[0030] Preferably, in S2, the sizes of zirconium dioxide ball milling beads are 4 mm and 6 mm, and the mass ratio is 2:1, the mass ratio of solid phase powder to ball milling beads is 1:2-3, the ball mill speed is 300-500 rpm, and the ball milling time is 2-4 h.

[0031] Preferably, in S3, the emulsifier is one or more of monostearate, zinc stearate, and cetyltrimethylammonium bromide, and the amount of the emulsifier is controlled so that the mass ratio of water to emulsifier in the mixed solution is 1:0.015-0.03.

[0032] Preferably, in S3, the mechanical dispersion speed is 200-300 rpm, and the temperature of the mixed liquid during the insulation process is 50-60°C.

[0033] Preferably, in S4, the heat treatment temperature is 800-1000°C, the treatment time is 8-12 h, and the heat treatment atmosphere is air. During the heat treatment process, the metal salt is converted into its oxide form, and the heteroatoms are removed in the form of gas, which is beneficial to improving the product purity and obtaining good capacity and cycle performance.

[0034] The present invention is further described below through several embodiments, which are only some of the embodiments of the present invention.

[0035] Example 1:

[0036] Take 0.10 mol of nickel hydroxide, 0.30 mol of manganese tetraoxide and 0.21 mol of nickel carbonate and completely disperse them in 65 g of water. The mixed solution is placed in a ball mill and ball milling beads are added thereto. 55.86 g of 4 mm diameter balls and 27.93 g of 6 mm diameter balls are added thereto. The mixture is ball milled at a speed of 500 rpm for 3 h. After the ball milling is completed, the mixed solution is taken out and sieved. 1.3 g of monostearate is added thereto and mechanical dispersion is maintained at a speed of 260 rpm. The temperature is slowly raised to 60 ° C and then kept warm. After the water in the mixed solution is completely evaporated, a nickel manganese lithium precursor powder is obtained. The mixture is placed in a tube furnace for heat treatment. The heat treatment conditions are 900 ° C and kept warm for 10 h to obtain a nickel manganese oxide lithium powder product.

[0037] Example 2:

[0038] Take 0.20 mol of nickel hydroxide, 0.60 mol of manganese tetraoxide and 0.42 mol of nickel carbonate and completely disperse them in 160 g of water. The mixed solution is placed in a ball mill and ball milling beads are added thereto. 133.03 g of 4 mm diameter balls and 61.50 g of 4 mm diameter balls are added thereto. The mixture is ball milled at a speed of 400 rpm for 4 h. After the ball milling is completed, the mixed solution is taken out and sieved. 2.72 g of stearic acid glyceride and zinc stearate with a mass ratio of one to one are added thereto. The mixture is mechanically dispersed at a speed of 240 rpm and slowly heated to 50 ° C and kept warm. After the water in the mixed solution is completely evaporated, a nickel manganese lithium precursor powder is obtained. The mixture is placed in a tube furnace for heat treatment. The heat treatment conditions are 1000 ° C and kept warm for 8 h to obtain a nickel manganese oxide lithium powder product.

[0039] Example 3:

[0040] Take 0.15 mol of nickel oxalate, 0.45 mol of manganese tetraoxide and 0.315 mol of nickel carbonate and completely disperse them in 102 g of water. The mixed solution is placed in a ball mill and ball milling beads are added thereto. 36.28 g of 4 mm diameter balls and 60.46 g of 6 mm diameter balls are added thereto. The mixture is ball milled at a speed of 300 rpm for 5 h. After the ball milling is completed, the mixed solution is taken out and sieved. 2.95 g of hexadecyltrimethylammonium bromide is added thereto and mechanical dispersion is maintained at a speed of 200 rpm. The temperature is slowly raised to 60°C and then kept warm. After the water in the mixed solution is completely evaporated, a nickel manganese lithium precursor powder is obtained. The mixture is placed in a tube furnace for heat treatment at 900°C for 8 h to obtain a nickel manganese oxide lithium powder product.

[0041] Example 4:

[0042] Take 0.30 mol of nickel hydroxide, 0.90 mol of manganese tetraoxide and 0.63 mol of nickel carbonate and completely disperse them in 187 g of water. The mixed solution is placed in a ball mill, and ball milling beads are added thereto. 198.23 g of 4 mm diameter balls and 96.97 g of 6 mm diameter balls are added thereto. The mixture is ball milled at a speed of 400 rpm for 5 h. After the ball milling is completed, the mixed solution is taken out and sieved. 4.30 g of hexadecyltrimethylammonium bromide and monostearate with a mass ratio of one to one are added thereto. The mixture is mechanically dispersed at a speed of 220 rpm, and the temperature is slowly raised to 50°C and then kept warm. After the water in the mixed solution is completely evaporated, a nickel manganese lithium precursor powder is obtained, which is placed in a tube furnace for heat treatment. The heat treatment conditions are 1000°C and kept warm for 9 h to obtain a nickel manganese oxide lithium powder product.

[0043] Comparative Example 1:

[0044] Take 0.10 mol of nickel carbonate, 0.30 mol of manganese tetraoxide, and 0.21 mol of nickel carbonate and completely disperse them in 45 g of water. The mixture is placed in a ball mill, and ball milling beads (36.28 g of 6 mm diameter beads and 60.46 g of 4 mm diameter beads) are added. The mixture is ball milled at 500 rpm for 3 h. After the ball milling is completed, the mixture is removed and sieved. Mechanical dispersion is maintained at 260 rpm, and the temperature is slowly raised to 60°C and then maintained. After the water in the mixture is completely evaporated, a nickel-manganese-lithium precursor powder is obtained. The precursor powder is placed in a tube furnace for heat treatment at 900°C for 10 h to obtain a lithium nickel manganese oxide powder product. This is recorded as Comparative Example 1.

[0045] like Figure 1 As shown, the microscopic morphology of lithium nickel manganese oxide prepared in Example 1 and Comparative Example 1 is compared. It can be seen from the SEM shooting results that the lithium nickel manganese oxide prepared by the scheme of the present invention has good sphericity, which confirms that the emulsification post-treatment has a beneficial effect on the secondary agglomeration of the particle product.

[0046] like Figure 2 As shown, the results of X-ray diffraction confirmed that the synthesized product was lithium nickel manganese oxide, and its crystal structure was spinel configuration.

[0047] Lithium nickel manganese oxide samples from the examples and comparative examples were used to prepare lithium-ion batteries and test their electrochemical performance. The specific preparation method involves completely dispersing lithium nickel manganese oxide, Super P, and PVDF in NMP at a ratio of 8:1:1. After sufficient dispersion, the mixture is coated on conductive aluminum foil and assembled into button cells. The discharge capacity test employed a test voltage range of 3.5-4.9 V. The electrochemical performance test results of the lithium nickel manganese oxide products from the examples and comparative examples are shown in Table 1 below:

[0048] Table 1 Electrochemical performance test results of lithium nickel manganese oxide products of the embodiment and comparative example

[0049]

[0050] All of these tests were performed using a constant current and constant voltage process for charge and discharge. Table 1 shows that in the examples, the 1 C discharge capacity ranged from 137.67 to 140.26 mAh / g; the capacity achieved upon first full charge was 126.58 to 131.62 mAh / g at 2 C, 115.89 to 116.39 mAh / g at 3 C, and 107.30 to 108.42 mAh / g at 5 C. Furthermore, the 1000-cycle capacity retention rate at 3 C was 84.42 to 86.50, both reaching high levels.

[0051] Figure 3The curves for the sample of Example 1 of the present invention during a 1 C charge-discharge capacity test are shown. In the rate performance test, the battery was tested at 1 C, 3 C, and 5 C charge-discharge rates (where 1 C equals 147 mAh / g). In the cycling performance test, the battery was cycled 1000 times at a 3 C rate. It is not difficult to see that the sample prepared in Example 1 of the present invention has relatively excellent capacity, high-rate performance, and long-term stable cycling performance among lithium-ion batteries.

[0052] In addition, the tap density of the example samples in Table 1 is higher than that of the comparative example.

[0053] The particle size test results of the lithium nickel manganese oxide samples of the embodiment and the comparative example are shown in Table 2 below. It can be seen that the d50 data of the embodiment sample is significantly lower than that of the comparative example sample, and the peak width of the particle size test result is also significantly narrower than that of the comparative example, which confirms that the scheme of the present invention reduces the influence of capillary force during the drying process, making the solid phase product particles more uniform.

[0054] Table 2 Particle size test results of lithium nickel manganese oxide products of Examples and Comparative Examples

[0055]

[0056] In summary, the present invention is based on ball milling solid-phase mixing and uses an emulsion method to control secondary particle agglomeration, which makes the obtained lithium nickel manganese oxide have more regular size characteristics. By adjusting the surface charge of the particles, the tap density of the product powder can be improved, thereby effectively shortening the lithium ion transmission path and effectively improving the battery rate and cycle performance.

[0057] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims.

[0058] Any matters not described in detail in the present invention are well-known technologies to those skilled in the art.

Claims

1. A method for preparing lithium nickel manganese oxide, characterized in that: Including the following specific contents: S1 prepares aqueous dispersions of nickel source, manganese source and lithium source; S2: placing the dispersion in a ball mill, adding zirconium dioxide ball milling beads, and running the ball mill in a planetary ball mill; After the mixed solution is taken out from the ball mill in S3, it is kept mechanically dispersed and heated. During the process, an emulsifier is continuously added to the mixed solution and then kept warm. The mixture is dispersed until the water is completely evaporated to obtain nickel-manganese-lithium precursor powder; After heat treatment of the S4 precursor powder, lithium nickel manganese oxide product is obtained, whose crystal structure is spinel configuration, and the microstructure is spherical particles observed by scanning electron microscopy.

2. The method for preparing lithium nickel manganese oxide according to claim 1, wherein: In S1, the nickel source is one or more of nickel carbonate, nickel oxalate, and nickel hydroxide; the manganese source is one or more of manganese tetraoxide, manganese carbonate, and manganese oxalate; and the lithium source is lithium carbonate and / or lithium hydroxide.

3. The method for preparing lithium nickel manganese oxide according to claim 2, wherein: The molar ratio of nickel and manganese in the aqueous dispersion is 1:3, the molar ratio of the sum of nickel and manganese atoms to lithium atoms is 2:1.1, and the mass ratio of solid phase powder to water in the aqueous dispersion is 1:1.5-2.

4. The method for preparing lithium nickel manganese oxide according to claim 1, wherein: In S2, the sizes of zirconium dioxide ball milling beads are divided into two types: 4 mm and 6 mm, and the mass ratio is 2:1, the mass ratio of solid phase powder to ball milling beads is 1:2-3, the ball mill speed is 300-500 rpm, and the ball milling time is 2-4 h.

5. The method for preparing lithium nickel manganese oxide according to claim 1, wherein: In S3, the emulsifier is one or more of monostearate, zinc stearate, and cetyltrimethylammonium bromide, and the amount of the emulsifier is controlled so that the mass ratio of water to emulsifier in the mixed solution is 1:0.015-0.

03.

6. The method for preparing lithium nickel manganese oxide according to claim 1, wherein: In the above S3, the mechanical dispersion speed is 200-300 rpm, and the temperature of the mixed liquid during the insulation process is 50-60°C.

7. The method for preparing lithium nickel manganese oxide according to claim 1, wherein: In the step S4, the heat treatment temperature is 800-1000° C., the treatment time is 8-12 h, and the heat treatment atmosphere is air.

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