A high-voltage high-rate lithium nickel manganese oxide cathode material and a preparation method thereof

Abstract

This invention discloses a high-voltage, high-rate lithium nickel manganese oxide cathode material and its preparation method, comprising the following steps: S1, weighing yttrium source, nickel source, and manganese source according to the stoichiometric ratio of Y:Ni:Mn, dissolving the three raw materials in water respectively, adding yttrium source aqueous solution, nickel source aqueous solution, and manganese source aqueous solution dropwise to citric acid aqueous solution, microwave-assisted heating to control the temperature of the solution at 60℃-80℃, stirring for a period of time, adding sodium bicarbonate aqueous solution and ammonia water to control the pH to 7-8, co-precipitating for a period of time, and then filtering, drying, and ball milling to obtain a preliminary yttrium-doped lithium nickel manganese oxide precursor; S2, mixing the precursor obtained in step S1 with a lithium source, and then calcining, annealing, and pulverizing to obtain a primary lithium nickel manganese oxide cathode material; S3, ball milling nickel phosphate and manganese phosphate into nanoparticles, uniformly coating the surface of the primary lithium nickel manganese oxide cathode material by spray drying, and then drying, calcining, annealing, pulverizing, sieving, and demagnetizing to obtain the lithium nickel manganese oxide cathode material.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, and in particular to a high-voltage, high-rate lithium nickel manganese oxide cathode material and its preparation method. Background Technology

[0002] In recent years, lithium-ion batteries have been widely used in 3C (computers, communications, and consumer electronics), energy storage, and power applications, and are receiving increasing attention. Cathode materials are a crucial component of lithium-ion batteries. With market development, compared to the currently widely commercialized ternary lithium batteries, spinel-structured lithium nickel manganese oxide (LiNi) batteries have gained popularity. 0.5 Mn 1.5 O4 (LNMO) is considered the most promising cathode material for next-generation lithium-ion batteries due to its abundant raw materials, superior rate capability, rapid three-dimensional lithium-ion conduction, and most importantly, its high energy density and high discharge plateau of approximately 4.7V. When lithium nickel manganese oxide is used as a cathode material, it has a spinel structure similar to lithium manganese oxide. During long-term battery cycling, transition metals nickel and manganese easily dissolve from the material, and the Jahn-Taller effect is prone to occur.

[0003] To fully utilize lithium nickel manganese oxide materials and overcome the problems of manganese dissolution and disproportionation, surface coating is an effective strategy to increase structural stability. However, while common oxide coatings such as alumina can stabilize cycling, their insulating properties hinder the rapid insertion and extraction of lithium ions. Therefore, this invention proposes a method for preparing lithium nickel manganese oxide coated with yttrium-doped nano-manganese phosphate and nickel phosphate. Summary of the Invention

[0004] The purpose of this invention is to improve the structural stability and thermal stability of lithium nickel manganese oxide cathode materials obtained by yttrium doping and nickel phosphate + manganese phosphate coating, as well as the preparation method thereof, and to improve the cycle performance and rate performance of batteries made from them. The preparation method is simple, low-cost, and easy to industrialize.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material, characterized by comprising the following steps:

[0007] S1. Weigh out yttrium source, nickel source and manganese source according to the stoichiometric ratio of Y:Ni:Mn. Dissolve the three raw materials in water respectively. Add yttrium source aqueous solution, nickel source aqueous solution and manganese source aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. After stirring for a period of time, sodium bicarbonate aqueous solution and ammonia water are added dropwise to control the pH to 7-8. After co-precipitation for a period of time, the solution is filtered, dried and ball-milled to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0008] S2. The precursor obtained in step S1 is mixed with a lithium source, and then calcined, annealed and pulverized to obtain a primary lithium nickel manganese oxide cathode material.

[0009] S3. Nickel phosphate and manganese phosphate are ball-milled into nanoparticles and uniformly coated onto the surface of primary lithium nickel manganese oxide cathode material by spray drying. Then, the cathode material is successively dried, calcined, annealed, crushed, sieved, and demagnetized to obtain yttrium-doped lithium nickel manganese oxide cathode material coated with manganese phosphate and nickel phosphate.

[0010] Using the above technical solution, in the lithium nickel manganese oxide precursor synthesis stage, yttrium is doped into the raw materials to stabilize the material structure and improve the thermal stability of the material. Microwave-assisted heating is then used to obtain nano-precursors with different surface orientations that preferentially grow. The precursors are mixed with the lithium source and calcined at high temperature to obtain the initial lithium nickel manganese oxide cathode material. Then, the surface is coated with nano-manganese phosphate and nickel phosphate. Since the transition metal phosphate provides high lithium-ion conductivity, the final result is a lithium nickel manganese oxide cathode material with high operating voltage platform, good cycle stability, and high rate capability.

[0011] Preferably, the yttrium source in step S1 is yttrium carbonate; the nickel source is one or a mixture of nickel sulfate, nickel nitrate, or nickel chloride; and the manganese source is one or a mixture of manganese sulfate, manganese nitrate, or manganese chloride.

[0012] Preferably, in step S1, the molar ratio of Y to Ni and Mn is 0.005:1:1.5. <Y:Ni:Mn<0.015:1:1.5。

[0013] Preferably, the stirring time in step S1 is at least 3 hours, and the co-precipitation time is at least 6 hours.

[0014] Preferably, the lithium source in step S2 is one or a mixture of lithium carbonate, lithium hydroxide, lithium acetate, and lithium nitrate.

[0015] Preferably, the calcination temperature in step S2 is 850℃-950℃.

[0016] Preferably, in step S3, the ratio of 0.005:0.005:1 < nickel phosphate: manganese phosphate: primary lithium nickel manganese oxide cathode material < 0.02:0.02:1.

[0017] Preferably, the drying temperature in step S3 is controlled at 60℃-80℃, the calcination temperature is 550-650℃, and the annealing time is 4-6h.

[0018] Preferably, in step S3, the ball-to-material ratio of the ball mill is (1-50):1, the rotation speed is 500r / min-800r / min, and the time is 2-8h; the sieve screen is 300 mesh.

[0019] A high-voltage, high-rate lithium nickel manganese oxide cathode material, comprising the lithium nickel manganese oxide cathode material prepared by the above-described preparation method.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] 1. In the preparation of yttrium-doped precursors, microwave-assisted heating makes the slurry more uniformly heated during co-precipitation, allowing yttrium to be uniformly distributed in the core structure of the precursor. The doping of yttrium can improve the thermal stability of the material.

[0022] 2. This invention improves the conductivity of lithium-manganese oxide cathode materials by coating them with manganese phosphate and nickel phosphate. This, combined with chromium doping increasing the interlayer spacing of the crystal, synergistically enhances the rapid insertion / extraction capability of potassium ions, thereby improving the rate performance of the material. Simultaneously, the manganese phosphate and nickel phosphate coating inhibits transition metal dissolution, improves the structural stability of the material, and the P-O bonds act as oxygen fixation agents, suppressing oxygen release and gas generation from the cathode material during cycling.

[0023] 3. The method of this invention is simple, low-cost, and produces products with excellent performance, making it suitable for industrialization. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0025] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0026] S1. Weigh out yttrium source, nickel source, and manganese source according to the stoichiometric ratio of Y:Ni:Mn. Dissolve the three raw materials in water respectively. Add yttrium source aqueous solution, nickel source aqueous solution, and manganese source aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. After stirring for at least 3 hours, sodium bicarbonate aqueous solution and ammonia water are added dropwise to control the pH to 7-8. After co-precipitation for at least 6 hours, the solution is filtered, dried, and ball-milled to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0027] S2. The precursor obtained in step S1 is mixed with a lithium source, and then calcined, annealed and pulverized to obtain a primary lithium nickel manganese oxide cathode material. The calcination temperature is 850℃-950℃.

[0028] S3. Ball mill nickel phosphate and manganese phosphate into nanoparticles with a ball-to-material ratio of (1-50):1, a rotation speed of 500 r / min-800 r / min, and a time of 2-8 h. Then, uniformly coat the primary nickel manganese oxide lithium cathode material with the nanoparticles by spray drying. Then, dry the nanoparticles at 60℃-80℃, calcine them at 550-650℃, anneal them for 4-6 h, pulverize them, sieve them through a 300-mesh screen, and remove magnetism to obtain yttrium-doped, manganese phosphate + nickel phosphate coated nickel manganese oxide lithium cathode material.

[0029] In step S1, the yttrium source is yttrium carbonate; the nickel source is one or a mixture of nickel sulfate, nickel nitrate, or nickel chloride; and the manganese source is one or a mixture of manganese sulfate, manganese nitrate, or manganese chloride. The molar ratio of Y to Ni and Mn is 0.005:1:1.5. <Y:Ni:Mn<0.015:1:1.5。

[0030] In step S2, the lithium source is one or a mixture of lithium carbonate, lithium hydroxide, lithium acetate, and lithium nitrate.

[0031] In step S3, the ratio of 0.005:0.005:1 < nickel phosphate: manganese phosphate: primary lithium nickel manganese oxide cathode material < 0.02:0.02:1.

[0032] Example 1

[0033] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0034] S1. Weigh yttrium carbonate, nickel sulfate, and manganese sulfate according to the elemental stoichiometry ratio of Y:Ni:Mn 0.01:1:3. Dissolve the three raw materials separately in deionized water. Add yttrium carbonate aqueous solution, nickel sulfate aqueous solution, and manganese sulfate aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry, and ball mill to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0035] S2. Yttrium-doped lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material. The mixed material is then calcined at 900℃ for 6 h, annealed for 6 h, and then air-jet pulverized to obtain primary lithium nickel manganese oxide cathode material.

[0036] S3. Manganese phosphate and nickel phosphate are ball-milled into nanoparticles and uniformly dispersed in isopropanol solution. The manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material is coated with manganese phosphate and nickel phosphate uniformly by spray drying at a mass ratio of manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode = 0.01:0.01:1. Then, the material is dried, heated to 550℃, calcined for 3 hours, annealed for 4 hours, air-jet pulverized, sieved through a 300-mesh screen, and demagnetized to obtain the final yttrium-doped, manganese phosphate + nickel phosphate coated lithium nickel manganese oxide cathode material.

[0037] Example 2

[0038] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0039] S1. Weigh yttrium carbonate, nickel sulfate, and manganese sulfate according to the elemental stoichiometry ratio of Y:Ni:Mn 0.005:1:3. Dissolve the three raw materials separately in deionized water. Add yttrium carbonate aqueous solution, nickel sulfate aqueous solution, and manganese sulfate aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry, and ball mill to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0040] S2. Yttrium-doped lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material. The mixed material is then calcined at 950℃ for 6 h, annealed for 6 h, and then air-jet pulverized to obtain primary lithium nickel manganese oxide cathode material.

[0041] S3. Manganese phosphate and nickel phosphate are ball-milled into nanoparticles and uniformly dispersed in isopropanol solution. The manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material is coated with manganese phosphate and nickel phosphate uniformly by spray drying at a mass ratio of manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode = 0.02: 0.02: 1. Then, the material is dried, heated to 550℃, calcined for 3 hours, annealed for 4 hours, air-jet pulverized, sieved through a 300-mesh screen, and demagnetized to obtain the final yttrium-doped, manganese phosphate + nickel phosphate coated lithium nickel manganese oxide cathode material.

[0042] Example 3

[0043] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0044] S1. Weigh yttrium carbonate, nickel sulfate, and manganese sulfate according to the elemental stoichiometry ratio of Y:Ni:Mn 0.015:1:3. Dissolve the three raw materials separately in deionized water. Add yttrium carbonate aqueous solution, nickel sulfate aqueous solution, and manganese sulfate aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry, and ball mill to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0045] S2. Yttrium-doped lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material. The mixed material is then calcined at 950℃ for 6 h, annealed for 6 h, and then air-jet pulverized to obtain primary lithium nickel manganese oxide cathode material.

[0046] S3. Manganese phosphate and nickel phosphate are ball-milled into nanoparticles and uniformly dispersed in isopropanol solution. Manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material is coated with manganese phosphate and nickel phosphate uniformly by spray drying at a mass ratio of manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material = 0.005: 0.005: 1. Then, the material is dried, heated to 600℃, calcined for 3 hours, annealed for 4 hours, air-jet pulverized, sieved through a 300-mesh screen, and demagnetized to obtain the final yttrium-doped, manganese phosphate + nickel phosphate coated lithium nickel manganese oxide cathode material.

[0047] Example 4

[0048] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0049] S1. Weigh yttrium carbonate, nickel sulfate, and manganese sulfate according to the elemental stoichiometry ratio of Y:Ni:Mn 0.005:1:3. Dissolve the three raw materials separately in deionized water. Add yttrium carbonate aqueous solution, nickel sulfate aqueous solution, and manganese sulfate aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry, and ball mill to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0050] S2. Yttrium-doped lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material. The mixed material is then calcined at 850℃ for 6 h, annealed for 6 h, and then air-jet pulverized to obtain primary lithium nickel manganese oxide cathode material.

[0051] S3. Manganese phosphate and nickel phosphate are ball-milled into nanoparticles and uniformly dispersed in isopropanol solution. Manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material is coated with manganese phosphate and nickel phosphate uniformly by spray drying at a mass ratio of manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material = 0.005: 0.005: 1. Then, the material is dried, heated to 650℃, calcined for 3 hours, annealed for 4 hours, air-jet pulverized, sieved through a 300-mesh screen, and demagnetized to obtain the final yttrium-doped, manganese phosphate + nickel phosphate coated lithium nickel manganese oxide cathode material.

[0052] Example 5

[0053] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0054] S1. Weigh yttrium carbonate, nickel sulfate, and manganese sulfate according to the elemental stoichiometry ratio of Y:Ni:Mn 0.01:1:3. Dissolve the three raw materials separately in deionized water. Add yttrium carbonate aqueous solution, nickel sulfate aqueous solution, and manganese sulfate aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry, and ball mill to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0055] S2. Yttrium-doped lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material. The mixed material is then calcined at 950℃ for 6 h, annealed for 6 h, and then air-jet pulverized to obtain primary lithium nickel manganese oxide cathode material.

[0056] S3. Manganese phosphate and nickel phosphate are ball-milled into nanoparticles and uniformly dispersed in isopropanol solution. The manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material is coated with manganese phosphate and nickel phosphate uniformly by spray drying at a mass ratio of manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode = 0.015: 0.015: 1. Then, the material is dried, heated to 600℃, calcined for 3 hours, annealed for 4 hours, air-jet pulverized, sieved through a 300-mesh screen, and demagnetized to obtain the final yttrium-doped, manganese phosphate + nickel phosphate coated lithium nickel manganese oxide cathode material.

[0057] Example 6

[0058] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0059] S1. Weigh yttrium carbonate, nickel nitrate, and manganese nitrate according to the elemental stoichiometry of Y:Ni:Mn 0.01:1:3. Dissolve the three raw materials separately in deionized water. Add yttrium carbonate aqueous solution, nickel nitrate aqueous solution, and manganese nitrate aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry, and ball mill to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0060] S2. Yttrium-doped lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material. The mixed material is then calcined at 900℃ for 6 h, annealed for 6 h, and then air-jet pulverized to obtain primary lithium nickel manganese oxide cathode material.

[0061] S3. Manganese phosphate and nickel phosphate are ball-milled into nanoparticles and uniformly dispersed in isopropanol solution. The manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material is coated with manganese phosphate and nickel phosphate uniformly by spray drying at a mass ratio of manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode = 0.01:0.01:1. Then, the material is dried, heated to 550℃, calcined for 3 hours, annealed for 4 hours, air-jet pulverized, sieved through a 300-mesh screen, and demagnetized to obtain the final yttrium-doped, manganese phosphate + nickel phosphate coated lithium nickel manganese oxide cathode material.

[0062] Example 7

[0063] A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material includes the following steps:

[0064] S1. Weigh yttrium carbonate, nickel chloride, and manganese chloride according to the elemental stoichiometry ratio of Y:Ni:Mn 0.01:1:3. Dissolve the three raw materials separately in deionized water. Add yttrium carbonate aqueous solution, nickel chloride aqueous solution, and manganese chloride aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry, and ball mill to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor.

[0065] S2. Yttrium-doped lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material. The mixed material is then calcined at 900℃ for 6 h, annealed for 6 h, and then air-jet pulverized to obtain primary lithium nickel manganese oxide cathode material.

[0066] S3. Manganese phosphate and nickel phosphate are ball-milled into nanoparticles and uniformly dispersed in isopropanol solution. The manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode material is coated with manganese phosphate and nickel phosphate uniformly by spray drying at a mass ratio of manganese phosphate: nickel phosphate: primary lithium nickel manganese oxide cathode = 0.01:0.01:1. Then, the material is dried, heated to 550℃, calcined for 3 hours, annealed for 4 hours, air-jet pulverized, sieved through a 300-mesh screen, and demagnetized to obtain the final yttrium-doped, manganese phosphate + nickel phosphate coated lithium nickel manganese oxide cathode material.

[0067] Comparison,

[0068] C1. Weigh nickel sulfate and manganese sulfate according to the Ni:Mn elemental stoichiometry ratio of 1:3. Dissolve the two raw materials in water. Add manganese sulfate aqueous solution and manganese sulfate aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. Stir for 3 hours. Add sodium bicarbonate aqueous solution and ammonia water dropwise to control the pH to 7-8. After precipitation for 6 hours, filter, dry and ball mill to obtain the primary nickel manganese lithium oxide precursor.

[0069] C2, primary lithium nickel manganese oxide precursor and lithium carbonate are mixed in a high-speed mixer at 950 r / min for 1 h to obtain a uniform mixed material; the mixed material is then calcined at 900℃ for 6 h, annealed for 6 h, air-jet pulverized, sieved and demagnetized to obtain lithium nickel manganese oxide cathode material.

[0070] The high-voltage, high-rate lithium nickel manganese oxide cathode materials prepared in Examples 1-7 and the cathode materials in the comparative examples were used to fabricate coin cells using lithium metal as the anode. Charge-discharge cycle experiments were conducted, with cutoff voltages ranging from 3.0 to 4.9 V. The test data are shown in the table below.

[0071]

[0072] Analysis of the above button cell test results shows that the performance of the product in Example 1 is significantly better than that of the comparative example. The doped and coated lithium nickel manganese oxide cathode in Example 1 retains 79.69% of its discharge capacity at 5C rate and 99.18% of its capacity at 1C rate for 50 cycles. In contrast, the undoped and uncoated lithium nickel manganese oxide cathode retains only 68.97% of its discharge capacity at 5C rate and 91.62% of its capacity at 1C rate for 50 cycles. This indicates that the uniform doping of yttrium in the lithium nickel manganese oxide structure and the uniform coating of manganese phosphate and nickel phosphate on the surface of the lithium nickel manganese oxide cathode result in better electrochemical performance.

[0073] This invention utilizes microwave-assisted heating and a co-precipitation method to prepare a uniformly yttrium-doped lithium nickel manganese oxide precursor from yttrium, nickel, and manganese sources. The primary precursor is then uniformly mixed with a lithium source and sintered to form a primary lithium nickel manganese oxide cathode material. The yttrium doping enhances the material's structural and thermal stability. Manganese phosphate and nickel phosphate are then ball-milled into nanoparticles and uniformly coated onto the surface of the primary lithium nickel manganese oxide cathode material via spray drying. After calcination, the final product is obtained. The lithium nickel manganese oxide cathode material prepared using this method significantly improves the cycle performance, thermal stability, and rate capability of lithium nickel manganese oxide, promoting its widespread application.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material, characterized in that, Includes the following steps: S1. Weigh out yttrium source, nickel source, and manganese source according to the stoichiometric ratio of Y:Ni:Mn satisfying 0.005:1:1.5 < Y:Ni:Mn < 0.015:1:1.

5. Dissolve the three raw materials in water respectively. Add yttrium source aqueous solution, nickel source aqueous solution, and manganese source aqueous solution dropwise to citric acid aqueous solution. Microwave-assisted heating is used to control the temperature of the solution at 60℃-80℃. After stirring for a period of time, sodium bicarbonate aqueous solution and ammonia water are added dropwise to control the pH to 7-8. After co-precipitation for a period of time, the solution is filtered, dried, and ball-milled to obtain the preliminary yttrium-doped lithium nickel manganese oxide precursor. S2. The precursor obtained in step S1 is mixed with a lithium source, and then calcined, annealed and pulverized at 850℃-950℃ to obtain a primary lithium nickel manganese oxide cathode material. S3. Nickel phosphate and manganese phosphate are ball-milled into nanoparticles and uniformly coated onto the surface of primary lithium nickel manganese oxide cathode material by spray drying. Then, the cathode material is successively dried, calcined, annealed, crushed, sieved, and demagnetized to obtain yttrium-doped lithium nickel manganese oxide cathode material coated with manganese phosphate and nickel phosphate. In step S3, the mass ratio of nickel phosphate, manganese phosphate, and primary lithium nickel manganese oxide cathode material is 0.005:0.005:1 < nickel phosphate: manganese phosphate: primary lithium nickel manganese oxide cathode material < 0.02:0.02:

1.

2. The method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material according to claim 1, characterized in that, The yttrium source in step S1 is yttrium carbonate; the nickel source is one or a mixture of nickel sulfate, nickel nitrate, or nickel chloride; and the manganese source is one or a mixture of manganese sulfate, manganese nitrate, or manganese chloride.

3. The method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material according to claim 1, characterized in that, The stirring time in step S1 is at least 3 hours; the co-precipitation time is at least 6 hours.

4. The method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S2, the lithium source is one or a mixture of lithium carbonate, lithium hydroxide, lithium acetate, and lithium nitrate.

5. The method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S3, the drying temperature is controlled at 60℃-80℃, the calcination temperature is 550-650℃, and the annealing time is 4-6h.

6. The method for preparing a high-voltage, high-rate lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S3, the ball-to-material ratio of the ball mill is (1-50):1, the rotation speed is 500r / min-800r / min, and the time is 2-8h; the sieve is 300 mesh.

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