Modified high-voltage lithium nickel manganese oxide positive electrode material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a modified high-voltage lithium nickel manganese oxide positive electrode material as well as a preparation method and application thereof. Lithium nickel manganese oxide reacts in a lithium aluminum hydrotalcite system, the crystal structure of the material can be regulated and controlled through bulk phase doping, a stable layer structure is formed through ion exchange with lithium aluminum hydrotalcite layers, and heating, drainage and drying are further performed, so that the structural stability and thermal stability of the lithium nickel manganese oxide material are improved; and when the material is used as a positive electrode material of a lithium ion battery, the electrochemical performance of the battery is favorably improved.

Description

Technical Field

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

[0002] Lithium nickel manganese oxide (LiMO) is a promising cathode material for lithium-ion batteries currently under development. Compared to lithium cobalt oxide, LiMO offers higher output voltage, lower cost, and environmental friendliness; compared to lithium manganese oxide, it exhibits better high-temperature cycle stability; and compared to lithium iron phosphate, its preparation process is simpler and batch stability is better. However, the surface structure of LiMO is unstable. During charge and discharge, chemical reactions occur on its surface upon contact with the electrolyte, leading to structural collapse and a significant reduction in lithium-ion insertion / extraction performance. Consequently, the specific capacity, cycle stability, and rate capability of LiMO do not adequately meet the requirements of practical applications.

[0003] To address the problems of lithium nickel manganese oxide materials, conventional modification methods involve metal doping (CN201811450413). However, this is not entirely suitable for lithium-rich lithium nickel manganese oxide cathode materials because additional lithium ions partially or completely occupy vacant sites, preventing other metal elements from effectively doping. Furthermore, metal doping cannot directly and effectively solve the problem of interfacial side reactions between the material and the electrolyte under high voltage. Therefore, elemental doping cannot fully meet the modification requirements of lithium-rich lithium nickel manganese oxide cathode materials. Research has found that surface coating is a good method to solve the interfacial side reaction problem and can meet the material modification needs of lithium-rich lithium nickel manganese oxide materials with different lithium contents. However, the choice of coating material and the uniformity of coating directly affect the coating effect. Conventional coating materials have poor conductivity, and after coating, they cannot simultaneously maintain the lithium-ion conductivity and electronic conductivity of the material. Inhomogeneous coating layers also cannot effectively improve the electrochemical performance of the material.

[0004] Therefore, it is necessary to find a modified material that can solve the problem of material cycle stability, suppress the dissolution of transition metal ions, and take into account the conduction characteristics of lithium ions and electrons in the material. At the same time, it is necessary to create a modification method that can improve the uniformity of the coating material, so as to efficiently achieve the modification of lithium-rich nickel manganese lithium oxide cathode materials.

[0005] Purpose of the invention

[0006] To overcome the shortcomings of existing technologies, the present invention aims to provide a modified high-voltage lithium nickel manganese oxide cathode material, its preparation method, and its applications. The present invention reacts lithium nickel manganese oxide in a lithium aluminum layered double hydroxide (LDH) system. The crystal structure of the material can be controlled through bulk doping, and a stable layer structure is formed through interlayer ion exchange with the LDH. Further heating and water drainage drying improves the structural and thermal stability of the lithium nickel manganese oxide material, enhancing its cycle performance and rate capability. Using it as a cathode material for lithium-ion batteries is beneficial for improving the electrochemical performance of the battery.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a modified high-voltage lithium nickel manganese oxide cathode material includes the following steps:

[0009] S1. Preparation of lithium nickel manganese oxide:

[0010] S101. Mix 10-30 parts by weight of lithium source, 5-10 parts by weight of nickel source and 100-120 parts by weight of isopropanol and stir for 30-40 minutes to obtain mixture A;

[0011] S102. Add 20-30 parts of complexing agent to mixture A, adjust the pH of the solution to 6-8, heat the solution to 100-110℃ and stir it for 2-3 hours to obtain wet gel;

[0012] S103. The wet gel is dried at 80-110℃ for 30-40 min, and then sintered at 600-650℃ for 7-8 h to obtain a nickel lithium oxide precursor.

[0013] S104. Mix 15-20 parts by weight of nickel lithium oxide precursor with 20-30 parts by weight of manganese source, and calcine in an oxygen atmosphere to obtain lithium nickel manganese oxide.

[0014] S2. Preparation of modified high-voltage lithium nickel manganese oxide cathode material:

[0015] S201. Mix 30-40 parts by weight of lithium source, 20-30 parts by weight of aluminum source and 1-15 parts by weight of urea in a reaction vessel and carry out a hydrothermal reaction at 80-90℃ for 12-18 hours.

[0016] S202. Add 10-15 parts of thallium chloride and 30-40 parts of lithium nickel manganese oxide to the reaction vessel described in step S201, and carry out a hydrothermal reaction at 100-120°C for 15-20 hours. Wash and dry the solid obtained after the reaction.

[0017] S203. The dried solid product obtained in step S202 is calcined, cooled to room temperature in the furnace, and ground through a 400-mesh sieve to obtain the modified high-voltage lithium nickel manganese oxide cathode material.

[0018] Preferably, in step S101, the lithium source is selected from one or more of lithium carbonate, lithium nitrate, and lithium hydroxide; and the nickel source is selected from one or more of nickel sulfate and nickel nitrate.

[0019] Preferably, in step S102, the complexing agent is a mixture of citric acid, ethylenediaminetetraacetic acid, and polyacrylic acid in a mass ratio of 1:1:1.

[0020] Preferably, in step S104, the manganese source is selected from one or more of manganese sulfate, manganese nitrate, and manganese acetate.

[0021] Preferably, in step S104, the working parameters of the calcination treatment are: calcination temperature of 500-700℃, calcination time of 4-8h, and heating rate of 5℃ / min.

[0022] Preferably, in step S201, the lithium source is selected from one or more of lithium chloride and lithium nitrate; the aluminum source is selected from one or more of aluminum sulfate, aluminum acetate, and aluminum chloride.

[0023] Preferably, in step S203, the working parameters of the calcination treatment are: calcination temperature of 500-600℃, calcination time of 5-6h, and heating rate of 8℃ / min.

[0024] A modified high-voltage lithium nickel manganese oxide cathode material is prepared according to the preparation method described above.

[0025] An application of the modified high-voltage lithium nickel manganese oxide cathode material in lithium-ion batteries.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention reacts lithium nickel manganese oxide in a lithium aluminum hydrotalcite system. The crystal structure of the material can be controlled by bulk doping, and a stable layer structure is formed by interlayer ion exchange with lithium aluminum hydrotalcite. Further heating and drainage drying improve the structural and thermal stability of the lithium nickel manganese oxide material, enhance its cycle performance and rate performance, and make it suitable for use as a cathode material in lithium-ion batteries, which is beneficial to improving the electrochemical performance of the battery. Attached Figure Description

[0028] Figure 1 This is a process flow diagram for preparing the modified high-voltage lithium nickel manganese oxide cathode material described in this invention;

[0029] Figure 2This is a flow chart of the preparation process of lithium nickel manganese oxide according to the present invention;

[0030] Figure 3 This is a process flow diagram for preparing the modified high-voltage lithium nickel manganese oxide cathode material described in this invention;

[0031] Figure 4 This is a SEM image of the modified high-voltage lithium nickel manganese oxide cathode material prepared in Example 1 of the present invention. Detailed Implementation

[0032] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Please see Figure 1-4 The present invention provides a technical solution:

[0034] Example 1

[0035] A method for preparing a modified high-voltage lithium nickel manganese oxide cathode material:

[0036] S1. Preparation of lithium nickel manganese oxide:

[0037] S101. Mix 10g lithium nitrate, 5g nickel sulfate and 100g isopropanol and stir for 30 minutes to obtain mixture A;

[0038] S102. Add 20g of a mixture of citric acid, ethylenediaminetetraacetic acid and polyacrylic acid in a mass ratio of 1:1:1 to mixture A, adjust the pH of the solution to 6.5, heat the solution to 100℃ and stir it for 2h to obtain a wet gel.

[0039] S103. The wet gel is dried at 80°C for 30 min and then sintered at 600°C for 7 h to obtain a nickel lithium oxide precursor;

[0040] S104. Mix 15g of nickel lithium oxide precursor with 20g of manganese acetate, heat to 600℃ at a rate of 5℃ / min, and calcine in an oxygen atmosphere for 5h to obtain lithium nickel manganese oxide.

[0041] S2. Preparation of modified high-voltage lithium nickel manganese oxide cathode material:

[0042] S201. Mix 30g lithium chloride, 20g aluminum sulfate and 8g urea in a reaction vessel and carry out a hydrothermal reaction at 80℃ for 12h;

[0043] S202. After adding 10g of thallium chloride and 30g of lithium nickel manganese oxide to the reaction vessel described in step S201, perform a hydrothermal reaction at 100°C for 15h, and wash and dry the solid obtained after the reaction.

[0044] S203. The dried solid product obtained in step S202 is calcined at 600°C at a rate of 8°C / min for 5 hours, then cooled to room temperature in the furnace and ground through a 400-mesh sieve to obtain the modified high-voltage lithium nickel manganese oxide cathode material.

[0045] Example 2

[0046] A method for preparing a modified high-voltage lithium nickel manganese oxide cathode material:

[0047] S1. Preparation of lithium nickel manganese oxide:

[0048] S101. Mix 15g lithium nitrate, 10g nickel sulfate and 100g isopropanol and stir for 40 minutes to obtain mixture A;

[0049] S102. Add 25g of a mixture of citric acid, ethylenediaminetetraacetic acid and polyacrylic acid in a mass ratio of 1:1:1 to mixture A, adjust the pH of the solution to 6.5, heat the solution to 100℃ and stir it for 2h to obtain a wet gel.

[0050] S103. The wet gel is dried at 80°C for 30 min and then sintered at 600°C for 8 h to obtain a nickel lithium oxide precursor;

[0051] S104. Mix 20g of nickel lithium oxide precursor with 25g of manganese acetate, heat to 600℃ at a rate of 5℃ / min, and calcine in an oxygen atmosphere for 5h to obtain lithium nickel manganese oxide.

[0052] S2. Preparation of modified high-voltage lithium nickel manganese oxide cathode material:

[0053] S201. Mix 40g lithium chloride, 30g aluminum sulfate and 15g urea in a reaction vessel and carry out a hydrothermal reaction at 80℃ for 12h;

[0054] S202. After adding 15g of thallium chloride and 40g of lithium nickel manganese oxide to the reaction vessel described in step S201, perform a hydrothermal reaction at 100°C for 20h, and wash and dry the solid obtained after the reaction.

[0055] S203. The dried solid product obtained in step S202 is calcined at 600°C at a rate of 8°C / min for 5 hours, then cooled to room temperature in the furnace and ground through a 400-mesh sieve to obtain the modified high-voltage lithium nickel manganese oxide cathode material.

[0056] Example 3

[0057] A method for preparing a modified high-voltage lithium nickel manganese oxide cathode material:

[0058] S1. Preparation of lithium nickel manganese oxide:

[0059] S101. Mix 10g lithium carbonate, 5g nickel nitrate and 100g isopropanol and stir for 30 minutes to obtain mixture A;

[0060] S102. Add 20g of a mixture of citric acid, ethylenediaminetetraacetic acid and polyacrylic acid in a mass ratio of 1:1:1 to mixture A, adjust the pH of the solution to 6.5, heat the solution to 100℃ and stir it for 2h to obtain a wet gel.

[0061] S103. The wet gel is dried at 80°C for 30 min and then sintered at 600°C for 7 h to obtain a nickel lithium oxide precursor;

[0062] S104. Mix 15g of nickel lithium oxide precursor with 20g of manganese sulfate, heat to 600℃ at a rate of 5℃ / min, and calcine in an oxygen atmosphere for 5h to obtain lithium nickel manganese oxide.

[0063] S2. Preparation of modified high-voltage lithium nickel manganese oxide cathode material:

[0064] S201. Mix 30g lithium nitrate, 20g aluminum chloride and 8g urea in a reaction vessel and carry out a hydrothermal reaction at 80℃ for 12h;

[0065] S202. After adding 10g of thallium chloride and 30g of lithium nickel manganese oxide to the reaction vessel described in step S201, perform a hydrothermal reaction at 100°C for 15h, and wash and dry the solid obtained after the reaction.

[0066] S203. The dried solid product obtained in step S202 is calcined at 600°C at a rate of 8°C / min for 5 hours, then cooled to room temperature in the furnace and ground through a 400-mesh sieve to obtain the modified high-voltage lithium nickel manganese oxide cathode material.

[0067] Example 4

[0068] A method for preparing a modified high-voltage lithium nickel manganese oxide cathode material:

[0069] S1. Preparation of lithium nickel manganese oxide:

[0070] S101. Mix 18g lithium hydroxide, 8g nickel sulfate and 100g isopropanol and stir for 30 minutes to obtain mixture A;

[0071] S102. Add 25g of a mixture of citric acid, ethylenediaminetetraacetic acid and polyacrylic acid in a mass ratio of 1:1:1 to mixture A, adjust the pH of the solution to 6.5, heat the solution to 100℃ and stir it for 2h to obtain a wet gel.

[0072] S103. The wet gel is dried at 80°C for 30 min and then sintered at 600°C for 7 h to obtain a nickel lithium oxide precursor;

[0073] S104. Mix 18g of nickel lithium oxide precursor with 27g of manganese sulfate, heat to 600℃ at a rate of 5℃ / min, and calcine in an oxygen atmosphere for 5h to obtain lithium nickel manganese oxide.

[0074] S2. Preparation of modified high-voltage lithium nickel manganese oxide cathode material:

[0075] S201. Mix 35g lithium chloride, 30g aluminum acetate and 12g urea in a reaction vessel and carry out a hydrothermal reaction at 80℃ for 12h.

[0076] S202. After adding 10g of thallium chloride and 30g of lithium nickel manganese oxide to the reaction vessel described in step S201, perform a hydrothermal reaction at 100°C for 15h, and wash and dry the solid obtained after the reaction.

[0077] S203. The dried solid product obtained in step S202 is calcined at 600°C at a rate of 8°C / min for 5 hours, then cooled to room temperature in the furnace and ground through a 400-mesh sieve to obtain the modified high-voltage lithium nickel manganese oxide cathode material.

[0078] Comparative Example

[0079] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that step S202, which originally existed in Example 1, was partially omitted in Comparative Example 1, thereby omitting the use of thallium chloride. The remaining steps are exactly the same in Comparative Example 1 and Example 1.

[0080] Comparative Example 2: Comparative Example 2 differs from Example 1 in that step S2, which originally existed in Example 1, is omitted in Comparative Example 2. Thus, only lithium nickel manganese oxide is prepared in Comparative Example 2, while the remaining steps are exactly the same in Comparative Example 2 and Example 1.

[0081] Performance testing:

[0082] The prepared modified high-voltage lithium nickel manganese oxide cathode material was cut into 10mm diameter, flat-edge circular electrode sheets using a stamping machine. The remaining materials were assembled into coin cells according to GB / T 43093-2023. The cycle performance and rate performance of the cells were tested, and the results are shown in Table 1.

[0083] Table 1. Cyclic performance and rate performance test data of Examples 1-4 and Comparative Examples 1-2

[0084]

[0085]

[0086] The charge-discharge specific capacity of Examples 1-4 and Comparative Examples 1-2 was tested, and the test results are shown in Table 2:

[0087] Table 2. Charge-discharge specific capacity test data of Examples 1-4 and Comparative Examples 1-2

[0088] Charging specific capacity (mAh / g) Discharge specific capacity (mAh / g) Coulomb efficiency (%) Example 1 143.1 142.8 99.86 Example 2 144.4 144.2 99.91 Example 3 140.1 138.1 98.65 Example 4 141.5 139.3 98.88 Comparative Example 1 136.7 133.7 98.44 Comparative Example 2 133.1 131.1 98.67

[0089] A comparison of the cycle performance and rate performance test data of Examples 1-4 and Comparative Examples 1-2 in Table 1 shows that the modified high-voltage lithium nickel manganese oxide cathode material prepared by the present invention has good cycle performance and rate performance. This is mainly because the present invention reacts lithium nickel manganese oxide in a lithium aluminum hydrotalcite system, regulates the crystal structure of the material through bulk doping, and forms a stable layer structure through interlayer ion exchange with lithium aluminum hydrotalcite. Further heating and water drainage drying improve the structural stability and thermal stability of the lithium nickel manganese oxide material, thereby significantly improving the cycle performance and rate performance of the prepared modified high-voltage lithium nickel manganese oxide cathode material.

[0090] A comparison of the charge-discharge specific capacity test data of Examples 1-4 and Comparative Examples 1-2 in Table 2 shows that the modified high-voltage lithium nickel manganese oxide cathode material prepared in this invention has a high charge-discharge specific capacity and good coulombic efficiency at a current density of 1C. The charge-discharge specific capacity of Examples 1-3 is higher than that of Comparative Example 1, which indicates that the doping of thallium metal improves the charge-discharge specific capacity and the lithium-ion and electron transport efficiency. The charge-discharge specific capacity of Examples 1-3 is significantly higher than that of Comparative Example 2, which indicates that the ion exchange between lithium nickel manganese oxide and lithium aluminum hydrotalcite forms a stable layer structure, improving the structural stability and thermal stability of the lithium nickel manganese oxide material, thereby improving the charge-discharge specific capacity.

[0091] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified high-voltage lithium nickel manganese oxide cathode material, characterized in that, Includes the following steps: S1. Preparation of lithium nickel manganese oxide: S101. Mix 10-30 parts by weight of lithium source, 5-10 parts by weight of nickel source and 100-120 parts by weight of isopropanol and stir for 30-40 minutes to obtain mixture A; S102. Add 20-30 parts of complexing agent to mixture A, adjust the pH of the solution to 6-8, heat the solution to 100-110℃ and stir it for 2-3 hours to obtain wet gel; S103. The wet gel is dried at 80-110℃ for 30-40 min, and then sintered at 600-650℃ for 7-8 h to obtain a nickel lithium oxide precursor. S104. Mix 15-20 parts by weight of nickel lithium oxide precursor with 20-30 parts by weight of manganese source, and calcine in an oxygen atmosphere to obtain lithium nickel manganese oxide. S2. Preparation of modified high-voltage lithium nickel manganese oxide cathode material: S201. Mix 30-40 parts by weight of lithium source, 20-30 parts by weight of aluminum source and 1-15 parts by weight of urea in a reaction vessel and carry out a hydrothermal reaction at 80-90℃ for 12-18 hours. S202. Add 10-15 parts of thallium chloride and 30-40 parts of lithium nickel manganese oxide to the reaction vessel described in step S201, and carry out a hydrothermal reaction at 100-120°C for 15-20 hours. Wash and dry the solid obtained after the reaction. S203. The dried solid product obtained in step S202 is calcined, cooled to room temperature in the furnace, and ground through a 400-mesh sieve to obtain the modified high-voltage lithium nickel manganese oxide cathode material.

2. The method for preparing a modified high-voltage lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S101, the lithium source is selected from one or more of lithium carbonate, lithium nitrate, and lithium hydroxide; the nickel source is selected from one or more of nickel sulfate and nickel nitrate.

3. The method for preparing a modified high-voltage lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S102, the complexing agent is a mixture of citric acid, ethylenediaminetetraacetic acid, and polyacrylic acid in a mass ratio of 1:1:

1.

4. The method for preparing a modified high-voltage lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S104, the manganese source is selected from one or more of manganese sulfate, manganese nitrate, and manganese acetate.

5. The method for preparing a modified high-voltage lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S104, the working parameters of the calcination treatment are: calcination temperature of 500-700℃, calcination time of 4-8h, and heating rate of 5℃ / min.

6. The method for preparing a modified high-voltage lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S201, the lithium source is selected from one or more of lithium chloride and lithium nitrate; the aluminum source is selected from one or more of aluminum sulfate, aluminum acetate, and aluminum chloride.

7. The method for preparing a modified high-voltage lithium nickel manganese oxide cathode material according to claim 1, characterized in that, In step S203, the working parameters of the calcination treatment are: calcination temperature of 500-600℃, calcination time of 5-6h, and heating rate of 8℃ / min.

8. A modified high-voltage lithium nickel manganese oxide cathode material, characterized in that, Prepared by the preparation method according to any one of claims 1-7.

9. The application of the modified high-voltage lithium nickel manganese oxide cathode material according to claim 8 in lithium-ion batteries.

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