A surface-coated lithium nickel manganese oxide, its preparation method and application

Abstract

The present invention belongs to the technical field of nanomaterial preparation, and provides a surface-coated lithium nickel manganese oxide and a preparation method and application thereof. The method comprises the following steps: in an inert atmosphere, subjecting a lithium nickel manganese oxide positive electrode material and trimethylaluminum to an adsorption reaction to obtain an intermediate lithium nickel manganese oxide; in an inert atmosphere, subjecting ozone and the intermediate lithium nickel manganese oxide to coating to obtain an intermediate; in an inert atmosphere, subjecting the intermediate to repeated adsorption reaction and coating to obtain the surface-coated lithium nickel manganese oxide. The preparation method provided by the present invention is simple, and an oxidation reaction can occur at a relatively low temperature by utilizing the strong oxidizing property of ozone, and a rapid reaction can occur after contacting the intermediate lithium nickel manganese oxide, which is convenient for rapid production of industrial assembly line ALD. The present invention also provides a surface-coated lithium nickel manganese oxide obtained by the preparation method, which has a high specific capacity and energy density, and has a high application value in the field of power batteries and energy storage systems.

Description

Technical Field

[0001] The present invention relates to the technical field of nano material preparation, and in particular to a surface-coated lithium nickel manganese oxide and a preparation method and application thereof. Background Art

[0002] Lithium nickel manganese oxide cathode materials are the development direction of the next generation of commercial lithium batteries due to their high voltage platform, high energy density and long cycle life. The performance of lithium battery cells is mainly determined by the cathode materials, and their performance is directly related to the energy density, safety and life of the battery cell and system. Surface coating is the main way to modify lithium nickel manganese oxide cathode materials. A uniform and dense coating layer can greatly improve the comprehensive performance of lithium nickel manganese oxide. The main coating methods are wet and dry. However, the dry ball milling-re-sintering technology has the defect of uneven coating layer, which is difficult to meet market demand. Summary of the invention

[0003] The purpose of the present invention is to provide a surface-coated lithium nickel manganese oxide and a preparation method and application thereof.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing surface-coated lithium nickel manganese oxide, comprising the following steps:

[0006] (1) In an inert atmosphere, a lithium nickel manganese oxide positive electrode material and trimethyl aluminum are subjected to an adsorption reaction to obtain an intermediate lithium nickel manganese oxide;

[0007] (2) in an inert atmosphere, coating ozone and intermediate lithium nickel manganese oxide to obtain an intermediate;

[0008] (3) In an inert atmosphere, the intermediate is subjected to repeated adsorption reaction of step (1) and coating of step (2) to obtain the surface-coated lithium nickel manganese oxide.

[0009] Preferably, the temperature of the trimethylaluminum in step (1) is 60-90°C; the carrier gas flow rate of the trimethylaluminum is 250-350 mbar, and the deposition rate of the trimethylaluminum is

[0010] Preferably, the temperature of the adsorption reaction in step (1) is 140-160° C., and the pulse time of the adsorption reaction is 0.3-0.7 s.

[0011] Preferably, the temperature of the ozone in step (2) is 60-90°C, the carrier gas flow rate of the ozone is 250-350 mbar, and the deposition rate of the ozone is

[0012] Preferably, the coating temperature in step (2) is 140-160° C., and the coating pulse time is 0.1-0.3 s.

[0013] Preferably, the number of repetitions in step (3) is 8 to 20 times.

[0014] The invention also provides surface-coated lithium nickel manganese oxide obtained by the preparation method.

[0015] The present invention also provides application of the surface-coated lithium nickel manganese oxide in lithium ion batteries.

[0016] The present invention has the following advantages:

[0017] The present invention provides a preparation method of surface-coated lithium nickel manganese oxide, comprising the following steps: in an inert atmosphere, subjecting a lithium nickel manganese oxide positive electrode material and trimethylaluminum to an adsorption reaction to obtain an intermediate lithium nickel manganese oxide; in an inert atmosphere, subjecting ozone and the intermediate lithium nickel manganese oxide to an encapsulation to obtain an intermediate; in an inert atmosphere, subjecting the intermediate to repeated adsorption reactions and encapsulation to obtain the surface-coated lithium nickel manganese oxide. The present invention utilizes the strong oxidizing property of ozone, and an oxidation reaction can occur at a relatively low temperature, and a rapid reaction can occur after contacting the intermediate lithium nickel manganese oxide, which is convenient for rapid production of industrial assembly line ALD.

[0018] The present invention also provides surface-coated lithium nickel manganese oxide obtained by the preparation method, which has high specific capacity and energy density and has high application value in the fields of power batteries and energy storage systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a comparison chart of the cycle performance of the lithium-ion battery prepared by coating the surface of lithium nickel manganese oxide in Example 1 and the lithium-ion battery prepared by the comparative example 1 without coating the surface of lithium nickel manganese oxide;

[0020] Figure 2 This is a transmission electron microscope image of the surface coated with lithium nickel manganese oxide in Example 1;

[0021] Figure 3 This is a transmission electron microscope image of the surface coated with lithium nickel manganese oxide in Example 2;

[0022] Figure 4 This is a transmission electron microscope image of the surface coated with lithium nickel manganese oxide in Example 3;

[0023] Figure 5 This is a transmission electron microscope image of the surface coated with lithium nickel manganese oxide in Example 4. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing surface-coated lithium nickel manganese oxide, comprising the following steps:

[0025] (1) In an inert atmosphere, a lithium nickel manganese oxide positive electrode material and trimethyl aluminum are subjected to an adsorption reaction to obtain an intermediate lithium nickel manganese oxide;

[0026] (2) in an inert atmosphere, coating ozone and intermediate lithium nickel manganese oxide to obtain an intermediate;

[0027] (3) In an inert atmosphere, the intermediate is subjected to repeated adsorption reaction of step (1) and coating of step (2) to obtain the surface-coated lithium nickel manganese oxide.

[0028] In the present invention, the thickness of the lithium nickel manganese oxide positive electrode material is preferably ≤0.1 mm, more preferably ≤0.08 mm, and more preferably ≤0.06 mm.

[0029] In the present invention, the lithium nickel manganese oxide positive electrode material is pre-treated and then subjected to an adsorption reaction with trimethylaluminum.

[0030] In the present invention, the pretreatment process of the lithium nickel manganese oxide positive electrode material comprises the following steps:

[0031] Place the lithium nickel manganese oxide positive electrode material into the ALD reaction chamber, evacuate the chamber, input inert gas protection, heat and wait for the reaction.

[0032] In the present invention, the inert gas is preferably Ar or N2; the target temperature of the heating is preferably 60 to 90°C, more preferably 65 to 85°C, and more preferably 70 to 80°C.

[0033] In the present invention, trimethylaluminum is transported to the reaction chamber through a carrier gas after being heated in a feed tank and an airway, and then undergoes an adsorption reaction with a lithium nickel manganese oxide positive electrode material.

[0034] In the present invention, the target temperature of the feed tank heating treatment is preferably 50-60°C, more preferably 53-57°C, and more preferably 54-56°C; the target temperature of the airway heating treatment is preferably 60-90°C, more preferably 65-85°C, and more preferably 70-80°C.

[0035] In the present invention, the target temperature of the airway heating is the subsequent temperature of trimethylaluminum.

[0036] In the present invention, the carrier gas is preferably Ar or N2.

[0037] In the present invention, the inert atmosphere in step (1) is preferably Ar or N2.

[0038] In the present invention, the temperature of the trimethylaluminum in step (1) is preferably 60 to 90°C, more preferably 65 to 85°C, and even more preferably 70 to 80°C.

[0039] In the present invention, the carrier gas flow rate of trimethylaluminum is preferably 250-350 mbar, more preferably 270-320 mbar, and even more preferably 285-315 mbar.

[0040] In the present invention, the deposition rate of trimethylaluminum is preferably More preferably More preferably

[0041] In the present invention, the temperature of the adsorption reaction in step (1) is preferably 140-160°C, more preferably 145-155°C, and even more preferably 148-152°C.

[0042] In the present invention, the pulse time of the adsorption reaction is preferably 0.3 to 0.7 s, more preferably 0.35 to 0.65 s, and even more preferably 0.4 to 0.5 s.

[0043] After the adsorption reaction is complete, inert gas is introduced into the reaction chamber for cleaning.

[0044] In the present invention, the inert gas is preferably Ar or N2; the pulse time of the inert gas is preferably 0.8 to 1.2 s, more preferably 0.9 to 1.1 s, and more preferably 0.95 to 1.05 s.

[0045] In the present invention, after being heated in the feed tank and the gas channel, ozone is transported to the reaction chamber through the carrier gas to react with the intermediate lithium nickel manganese oxide in a coating reaction.

[0046] In the present invention, the target temperature of the feed tank heating treatment is preferably 50-60°C, more preferably 53-57°C, and more preferably 54-56°C; the target temperature of the airway heating treatment is preferably 60-90°C, more preferably 65-75°C, and more preferably 68-72°C.

[0047] In the present invention, the target temperature of the airway heating is the temperature of the subsequent ozone.

[0048] In the present invention, the inert atmosphere in step (2) is preferably Ar or N2.

[0049] In the present invention, the temperature of the ozone in step (2) is preferably 60 to 90°C, more preferably 65 to 75°C, and even more preferably 68 to 72°C.

[0050] In the present invention, the carrier gas flow rate of the ozone is preferably 250 to 350 mbar, more preferably 270 to 320 mbar, and even more preferably 285 to 315 mbar.

[0051] In the present invention, the deposition rate of ozone is More preferably More preferably

[0052] In the present invention, the coating temperature in step (2) is preferably 140-160°C, more preferably 145-155°C, and even more preferably 148-152°C.

[0053] In the present invention, the pulse time of the coating is preferably 0.1 to 0.3 s, more preferably 0.12 to 0.28 s, and even more preferably 0.18 to 0.22 s.

[0054] In the present invention, the inert atmosphere in step (3) is preferably Ar or N2.

[0055] In the present invention, the number of repetitions in step (3) is preferably 8 to 20 times, more preferably 12 to 16 times, and even more preferably 13 to 15 times.

[0056] The invention also provides surface-coated lithium nickel manganese oxide obtained by the preparation method.

[0057] In the present invention, after multiple atomic-scale coatings of trimethylaluminum and ozone, the above-mentioned precursor forms molecules on the surface of the particles, which are adsorbed and deposited on the lithium nickel manganese oxide positive electrode material in the form of a monolayer of molecules, forming an inert functional coating on the surface of the lithium nickel manganese oxide. The thickness of the inert functional coating is preferably 5.5 to 41 nm, more preferably 10 to 30 nm, and more preferably 15 to 25 nm.

[0058] The invention also provides application of surface-coated lithium nickel manganese oxide in lithium ion batteries.

[0059] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] 10g of lithium nickel manganese oxide positive electrode material with a thickness of 0.08mm was placed into the ALD reaction chamber, and after evacuation, N2 was input and the lithium nickel manganese oxide positive electrode material was heated to 80°C.

[0062] Trimethylaluminum was heated to 60°C in the feed tank and then to 80°C in the gas channel. It was transported to the reaction chamber by N2 at a flow rate of 350mbar. The deposition rate was controlled at 150°C in the reaction chamber. The pulse is 0.5s to undergo adsorption reaction with the lithium nickel manganese oxide positive electrode material to obtain intermediate lithium nickel manganese oxide.

[0063] High-purity argon gas was input to clean the reaction chamber, and the pulse reaction time was 1 s.

[0064] Ozone is introduced into the feed tank, heated to 60°C, and then heated to 80°C through the gas channel. It is transported to the reaction chamber at 350mbar through N2. The deposition rate is controlled at 150°C in the reaction chamber. The pulse is 0.2s and the intermediate lithium nickel manganese oxide is coated to obtain an intermediate.

[0065] The above adsorption and coating reaction is repeated 8 times to obtain the surface-coated lithium nickel manganese oxide.

[0066] The surface-coated lithium nickel manganese oxide prepared in this example is used to further prepare a lithium ion battery, and a high-resolution transmission electron microscope (HRTEM) is used for testing. The cycle performance of the prepared lithium ion battery is as follows: Figure 1 shown.

[0067] Figure 2 HRTEM image of the surface-coated lithium nickel manganese oxide prepared in this example. Figure 2 As shown, the ozone ALD coating layer is a uniform layered structure, and the average thickness of the uniform coating layer is about 5.5 nm.

[0068] Example 2

[0069] 10g of lithium nickel manganese oxide positive electrode material with a thickness of 0.08mm was placed in the ALD reaction chamber, and after evacuation, Ar was input and then heated to 80°C for the lithium nickel manganese oxide positive electrode material.

[0070] Trimethylaluminum was heated to 60°C in the feed tank and then to 80°C in the gas channel. It was transported to the reaction chamber by Ar at 280 mbar. The deposition rate was 2.3 % at 150°C in the reaction chamber. The pulse is 0.5s to undergo adsorption reaction with the lithium nickel manganese oxide positive electrode material to obtain intermediate lithium nickel manganese oxide.

[0071] High-purity argon gas was input to clean the reaction chamber, and the pulse reaction time was 1 s.

[0072] Ozone was introduced into the feed tank, heated to 60°C, and then heated to 80°C through the gas channel. It was transported to the reaction chamber by Ar at 280 mbar. The deposition rate was 2.3 % at 150°C in the reaction chamber. The pulse is 0.2s and the intermediate lithium nickel manganese oxide is coated to obtain an intermediate.

[0073] The above adsorption and coating reaction is repeated 12 times to obtain the surface-coated lithium nickel manganese oxide.

[0074] Figure 3 This is the HRTEM image of the lithium nickel manganese oxide positive electrode material uniformly coated by ozone ALD in Example 2. Figure 3As shown, the ozone ALD coating layer is a uniform layered structure, and the average thickness of the uniform coating layer is about 8.5 nm.

[0075] Example 3

[0076] 10g of lithium nickel manganese oxide positive electrode material with a thickness of 0.09mm was placed in the ALD reaction chamber, and after evacuation, Ar was input and the lithium nickel manganese oxide positive electrode material was heated to 90°C.

[0077] Trimethylaluminum was heated to 55°C in the feed tank and then to 75°C in the gas channel. It was transported to the reaction chamber by Ar at a flow rate of 280 mbar. The deposition rate was 2.3 % at 160°C in the reaction chamber. The pulse is 0.5s to undergo adsorption reaction with the lithium nickel manganese oxide positive electrode material to obtain intermediate lithium nickel manganese oxide.

[0078] High-purity argon gas was input to clean the reaction chamber, and the pulse reaction time was 1 s.

[0079] Ozone was introduced into the feed tank, heated to 55°C, and then heated to 75°C through the gas channel. It was transported to the reaction chamber by Ar at a flow rate of 280 mbar. The deposition rate was 2.5 % at 160°C in the reaction chamber. The pulse is 0.2s and the intermediate lithium nickel manganese oxide is coated to obtain an intermediate.

[0080] The above adsorption and coating reaction is repeated 16 times to obtain the surface-coated lithium nickel manganese oxide.

[0081] Figure 4 This is the HRTEM image of the lithium nickel manganese oxide positive electrode material uniformly coated by ozone ALD in this embodiment 3. Figure 4 As shown, the ozone ALD coating layer is a uniform layered structure, and the average thickness of the uniform coating layer is about 17.5 nm.

[0082] Example 4

[0083] 10g of lithium nickel manganese oxide positive electrode material with a thickness of 0.09mm was placed into the ALD reaction chamber, and after evacuation, Ar was input and the lithium nickel manganese oxide positive electrode material was heated to 85°C.

[0084] Trimethylaluminum was heated to 60°C in the feed tank and then to 78°C in the gas channel. It was transported to the reaction chamber by Ar at a flow rate of 290 mbar. The deposition rate was 2.3 % at 155°C in the reaction chamber. The pulse is 0.5s to undergo adsorption reaction with the lithium nickel manganese oxide positive electrode material to obtain intermediate lithium nickel manganese oxide.

[0085] High-purity argon gas was input to clean the reaction chamber, and the pulse reaction time was 1 s.

[0086] Ozone was introduced into the feed tank, heated to 60°C, and then heated to 78°C through the gas channel. It was transported to the reaction chamber by Ar at a flow rate of 290 mbar. The deposition rate was 2.3 % at a temperature of 155°C in the reaction chamber. The pulse is 0.2s and the intermediate lithium nickel manganese oxide is coated to obtain an intermediate.

[0087] The above adsorption and coating reaction is repeated 20 times to obtain the surface-coated lithium nickel manganese oxide.

[0088] Figure 5 This is the HRTEM image of the lithium nickel manganese oxide positive electrode material uniformly coated by ozone ALD in Example 4. Figure 5 As shown, the ozone ALD coating layer is a uniform layered structure, and the average thickness of the uniform coating layer is about 41 nm.

[0089] Comparative Example 1

[0090] In this comparative example, the lithium nickel manganese oxide positive electrode material is not ozone coated, that is, 10 g of 0.08 mm lithium nickel manganese oxide positive electrode material particles are preheated to obtain an uncoated nickel cobalt manganese positive electrode material.

[0091] The uncoated lithium nickel manganese oxide positive electrode material prepared above is used to further prepare a lithium ion battery. The cycle performance of the prepared lithium ion battery is as follows: Figure 1 shown.

[0092] It can be seen from the above embodiments that the present invention provides a method for preparing surface-coated lithium nickel manganese oxide, which is characterized in that it comprises the following steps: in an inert atmosphere, subjecting a lithium nickel manganese oxide positive electrode material and trimethylaluminum to an adsorption reaction to obtain an intermediate lithium nickel manganese oxide; in an inert atmosphere, subjecting ozone and the intermediate lithium nickel manganese oxide to an encapsulation to obtain an intermediate; in an inert atmosphere, subjecting the intermediate to repeated adsorption reactions and encapsulation steps to obtain the surface-coated lithium nickel manganese oxide.

[0093] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing surface-coated lithium nickel manganese oxide, characterized in that: It includes the following steps: (1) In an inert atmosphere, a lithium nickel manganese oxide positive electrode material and trimethyl aluminum are subjected to an adsorption reaction to obtain an intermediate lithium nickel manganese oxide; (2) in an inert atmosphere, coating ozone and intermediate lithium nickel manganese oxide to obtain an intermediate; (3) in an inert atmosphere, repeating the adsorption reaction of step (1) and the coating of step (2) on the intermediate to obtain the surface-coated lithium nickel manganese oxide; The temperature of the adsorption reaction in step (1) is 140-160° C., and the pulse time of the adsorption reaction is 0.3-0.7 s; In step (2), the temperature of the ozone is 60-90° C., the carrier gas flow rate of the ozone is 250-350 mbar, and the deposition rate of the ozone is 1.8-9.1 Å / min; The coating temperature in step (2) is 140-160° C., and the coating pulse time is 0.1-0.3 s.

2. The preparation method according to claim 1, characterized in that The temperature of the trimethylaluminum in step (1) is 60-90° C.; the carrier gas flow rate of the trimethylaluminum is 250-350 mbar; and the deposition rate of the trimethylaluminum is 1.8-9.1 Å / min.

3. The preparation method according to claim 1, characterized in that: The number of repetitions in step (3) is 8 to 20 times.

4. The surface-coated lithium nickel manganese oxide obtained by the preparation method according to any one of claims 1 to 3.

5. Use of the surface-coated lithium nickel manganese oxide according to claim 4 in lithium ion batteries.

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