A coating material of single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide and its production method and application

Abstract

The invention discloses a coating material of single-crystal lithium manganate coated with nickel-cobalt lithium manganate, and a production method and application thereof, belonging to the technical field of lithium ion battery materials; the coating material of single-crystal lithium manganate coated with nickel-cobalt lithium manganate comprises single-crystal lithium manganate and nickel-cobalt lithium manganate; single-crystal lithium manganate with smaller particles is used as the coating material, which can effectively improve the safety of the nickel-cobalt lithium manganate material, and further a wet coating process is used to make the coating material evenly distributed, which can effectively improve the circulation, high temperature and safety performance of the coating material.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery materials, and in particular to a coating material of single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide, and a production method and application thereof. Background Art

[0002] Lithium-ion batteries, as a new energy industry, have been promoted throughout the world and are widely used in digital products, power tools, electric vehicles and electric vehicles. Among them, the technological innovation of positive electrode materials has always been the focus and development direction of research in the industry.

[0003] At present, the field of lithium-ion battery positive electrode materials generally uses several materials such as lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, and lithium manganese oxide. These materials have different focuses in terms of performance. Overall, lithium nickel cobalt manganese oxide materials (LiNi x Co y Mn 1-x-y O2) has higher energy density, voltage platform, rate, cycle, high temperature and other properties.

[0004] However, nickel cobalt manganese oxide materials have poor thermal stability and strong chemical reactions under high temperature conditions, which can easily cause spontaneous combustion. Their safety performance has always limited the development of the material. Therefore, there is an urgent need to find a process to improve the safety of nickel cobalt manganese oxide materials, which is of great significance to the application of nickel cobalt manganese oxide materials. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt lithium manganese oxide, and its production method and application. Single-crystal lithium manganese oxide with smaller particles is used as the coating material, which can effectively improve the safety of the nickel-cobalt lithium manganese oxide material. Further, a wet coating process is used to make the coating material evenly distributed, which can effectively improve the circulation, high temperature and safety performance of the coating material.

[0006] In order to achieve the above-mentioned object of the invention, the embodiment of the present invention adopts the following technical solution:

[0007] A coating material of single-crystal lithium manganate coated with nickel-cobalt lithium manganate, the coating material comprises single-crystal lithium manganate and nickel-cobalt lithium manganate.

[0008] The embodiment of the present invention also provides a method for producing the coating material of the above-mentioned single-crystal lithium manganese oxide coated with nickel-cobalt lithium manganese oxide, comprising the following steps:

[0009] (1) placing single crystal lithium manganese oxide in a grinding device and grinding it for 60-180 seconds to obtain material A;

[0010] (2) placing the lithium nickel cobalt manganese oxide material, alumina balls and deionized water in a ball mill and mixing them for 20-40 minutes;

[0011] (3) adding material A from step (1) to step (2) and mixing for 60-120 min to obtain material B;

[0012] (4) After filtering the alumina balls in material B, the material enters a stirring device and is stirred and spray-dried at the same time until the spray-drying process is completed, thereby obtaining material C;

[0013] (5) The material C in step (4) is sintered, crushed, sieved, and iron removed to obtain a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt lithium manganese oxide.

[0014] Furthermore, the particle size of material A in step (1) is 2-6 μm.

[0015] Furthermore, the grinding device in step (1) is a high-speed grinder.

[0016] Furthermore, in the step (2), the mass ratio of the lithium nickel cobalt manganese oxide material: alumina balls: deionized water is (0.5-1.5): (0.5-1.5): 2; and the particle size of the alumina balls is 20-40 mm.

[0017] Furthermore, the ball milling device in step (2) is a horizontal ball mill with a rotation speed of 60-80R / min.

[0018] Furthermore, in step (3), the rotation speed is 20-40 R / min.

[0019] Furthermore, the mass ratio of material A to nickel-cobalt-manganese acid in step (3) is (0.5-1.5):1000.

[0020] Furthermore, in step (4), the stirring speed is 30-50 R / min; and the spray drying temperature is 260-280°C.

[0021] Furthermore, in the step (5), the sintering temperature is 300-650° C. and the sintering time is 4-8 hours.

[0022] Furthermore, the mesh size of the sieve in step (5) is 200-400.

[0023] An embodiment of the present invention also provides a coating material of single-crystal lithium manganate coated with nickel-cobalt-lithium manganate or a coating material of single-crystal lithium manganate coated with nickel-cobalt-lithium manganate obtained by a production method of a coating material of single-crystal lithium manganate coated with nickel-cobalt-lithium manganate in a positive electrode material of a battery.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention uses single-crystal lithium manganese oxide as a coating material, which has a better coating effect. At low temperatures, the coating material can be evenly distributed on the surface of the coating material, making it tightly bonded. After cooling, the coating layer forms an effective protective film; single-crystal lithium manganese oxide has a strong ability to resist hydrofluoric acid corrosion, thereby effectively reducing the violent reaction of the material under high temperature conditions, making the thermal stability of the material higher; single-crystal lithium manganese oxide as a coating material can achieve a complementary effect with nickel-cobalt lithium manganese oxide, so that the coating material has higher voltage stability and safety.

[0026] (2) The present invention provides a method for producing a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt lithium manganese oxide, using alumina balls as a mixing medium to promote mixing effect; in the ball milling process, two different rotation speeds are used, the purpose of the first stage is to disperse the raw materials evenly, the rotation speed is relatively high, and the purpose of the second stage is to coat the materials, the rotation speed is relatively low; the purpose of setting a stirring device is to prevent the raw materials from settling; the wet coating process is used to make the coating material evenly distributed, which can effectively improve the circulation, high temperature and safety performance of the material.

[0027] (3) After the single crystal lithium manganese oxide coated nickel cobalt lithium manganese oxide coating material of the present invention is made into a battery, the cycle performance can be improved to more than 3000 cycles at room temperature 0.5°C with a retention rate of 75%, and the battery terminal stability and safety can be improved in a high temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood and to more clearly illustrate the technical solutions of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a 500-fold scanning electron microscope of the coating material of the single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide in Example 1.

[0030] Figure 2 This is a scanning electron microscope at 2000 times magnification of the coating material of the single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide in Example 1.

[0031] Figure 3 This is a 5000x scanning electron microscope of the coating material of the single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide in Example 1.

[0032] Figure 4 The battery was made of the coating material of single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide in Example 1 and then the charging and discharging performance was tested. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Example 1

[0035] The embodiment of the present invention provides a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt-lithium manganese oxide, comprising single-crystal lithium manganese oxide and nickel-cobalt-lithium manganese oxide.

[0036] The method for producing the coating material of the above-mentioned single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide comprises the following steps:

[0037] (1) Take 1 kg of single crystal lithium manganese oxide with a particle size distribution of d50 of 9 μm, place it in a high-speed grinder and grind it for 60 seconds. The obtained material A has a particle size distribution of d50 of about 5 μm, and seal it for later use.

[0038] (2) Weigh 5 kg of lithium nickel cobalt manganese oxide material, 5 kg of alumina balls, and 10 kg of deionized water, and put them into a horizontal ball mill in sequence, with a rotation speed of 80 R / min and a time of 30 min; the diameter of the alumina balls selected is 20 mm and 25 mm, 2.5 kg each.

[0039] (3) Weigh 5 g of material A and put it into a horizontal ball mill at a speed of 30 R / min for 120 min to obtain material B.

[0040] (4) Add a filter screen to the filtration port, add deionized water and extract multiple times to filter the alumina balls in material B, then put it into the stirring tank, stir it, start the spray drying tower, heat it to 250°C, spray dry the slurry in the stirring tank, and stir at a speed of 30R / min until the spray drying process is completed to obtain material C.

[0041] (5) Place material C in an atmosphere furnace for sintering, raise the temperature to 500°C at a rate of 6°C / min, and keep the temperature for 8 hours. During the process, air is introduced at a flow rate of 0.5m 3 / h; after sintering, crushing, screening and iron removal are carried out to obtain a coating material of single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide.

[0042] The coating material was scanned by electron microscope at 500 times, 2000 times and 8000 times. For details, please see the attached manual. Figure 1 / 2 / 3.

[0043] Attached to the instruction manual Figure 1 / 2 / 3 The finished product scanning electron microscope shows that the material has a complete crystal structure, the crystal surface has a complete protective layer, and it is evenly distributed, with a good coating effect.

[0044] Using the soft pack battery manufacturing method, single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide was made into batteries. The battery was tested for charging and discharging performance, and the results are shown in Figure 4 .

[0045] from Figure 4 It can be seen that the cycle performance test of charge and discharge at a half-point cell rate of 0.5C (2.75-4.3V) can improve the cycle performance to 75% for more than 3000 cycles at room temperature and 0.5C, which is nearly doubled compared with the cycle performance of conventional material batteries (80% capacity retention rate at room temperature and 0.5C for 800-1500 cycles).

[0046] Example 2

[0047] The embodiment of the present invention provides a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt-lithium manganese oxide, comprising single-crystal lithium manganese oxide and nickel-cobalt-lithium manganese oxide.

[0048] The method for producing the coating material of the above-mentioned single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide comprises the following steps:

[0049] (1) Take 1 kg of single crystal lithium manganese oxide with a particle size distribution of d50 of 9 μm, place it in a high-speed grinder and grind it for 120 seconds. The obtained material A has a particle size distribution of d50 of about 4 μm, and seal it for later use.

[0050] (2) Weigh 2.5 kg of lithium nickel cobalt manganese oxide material, 2.5 kg of alumina balls, and 10 kg of deionized water, and put them into a horizontal ball mill in sequence, with a rotation speed of 70 R / min and a time of 30 min; the diameter of the alumina balls is 30 mm and 35 mm, and each is 2.5 kg.

[0051] (3) Weigh 7.5 g of material A and put it into a horizontal ball mill at a speed of 20 R / min for 120 min to obtain material B.

[0052] (4) Add a filter screen to the filtration port, add deionized water and extract multiple times to filter the alumina balls in material B, then put it into the stirring tank, stir it, start the spray drying tower, heat it to 250°C, spray dry the slurry in the stirring tank, and stir at a speed of 40R / min until the spray drying process is completed to obtain material C.

[0053] (5) Place material C in an atmosphere furnace for sintering, raise the temperature to 500°C at a rate of 6°C / min, and keep the temperature for 8 hours. During the process, air is introduced at a flow rate of 0.5m 3 / h; after sintering, crushing, screening and iron removal are carried out to obtain a coating material of single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide.

[0054] Using a soft pack battery manufacturing method, single crystal lithium manganese oxide is coated with nickel cobalt lithium manganese oxide coating materials to make batteries.

[0055] Example 3

[0056] The embodiment of the present invention provides a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt-lithium manganese oxide, comprising single-crystal lithium manganese oxide and nickel-cobalt-lithium manganese oxide.

[0057] The method for producing the coating material of the above-mentioned single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide comprises the following steps:

[0058] (1) Take 1 kg of single crystal lithium manganese oxide with a particle size distribution of d50 of 9 μm, place it in a high-speed grinder and grind it for 180 seconds. The obtained material A has a particle size distribution of d50 of about 3 μm, and seal it for later use.

[0059] (2) Weigh 7.5 kg of lithium nickel cobalt manganese oxide material, 7.5 kg of alumina balls, and 10 kg of deionized water, and put them into a horizontal ball mill in sequence at a speed of 80 R / min for 30 min; the diameter of the alumina balls is 20 mm and 25 mm, 2.5 kg each.

[0060] (3) Weigh 10 g of material A and put it into a horizontal ball mill at a speed of 40 R / min for 120 min to obtain material B.

[0061] (4) Add a filter screen to the filtration port, add deionized water and extract multiple times to filter the alumina balls in material B, then put it into the stirring tank, stir it, start the spray drying tower, heat it to 250°C, spray dry the slurry in the stirring tank, and stir at a speed of 50R / min until the spray drying process is completed to obtain material C.

[0062] (5) Material C is placed in an atmosphere furnace for sintering, and the temperature is raised to 500° C. at a rate of 6° C. / min, and kept warm for 8 hours. During the process, air is introduced at a flow rate of 0.5 m3 / h; after sintering, the material is crushed, sieved, and iron is removed to obtain a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt lithium manganese oxide.

[0063] Using a soft pack battery manufacturing method, single crystal lithium manganese oxide is coated with nickel cobalt lithium manganese oxide coating materials to make batteries.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt lithium manganese oxide, characterized in that: The steps include: (1) placing single crystal lithium manganese oxide in a grinding device and grinding it for 60-180 seconds to obtain material A; (2) Place the lithium nickel cobalt manganese oxide material, alumina balls and deionized water in a ball mill and mix for 20-40 minutes; (3) Add material A from step (1) to step (2) and mix for 60-120 min at a speed of 20-40 r / min to obtain material B; (4) After filtering the alumina balls in material B, the material enters the stirring device at a stirring speed of 30-50 r / min, and spray-drying is performed while stirring at a spray-drying temperature of 260-280°C until the spray-drying process is completed, thereby obtaining material C; (5) sintering, crushing, screening and iron removal of the material C in step (4) to obtain a coating material of single-crystal lithium manganese oxide coated with nickel-cobalt lithium manganese oxide; The mass ratio of the lithium nickel cobalt manganese oxide material: alumina ball: deionized water in step (2) is (0.5-1.5): (0.5-1.5): 2; the particle size of the alumina ball is 20-40 mm; The coating material includes single crystal lithium manganese oxide and nickel cobalt lithium manganese oxide.

2. The method for producing single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide according to claim 1, characterized in that: The particle size of material A in step (1) is 2-6 μm; and the grinding device is a high-speed grinder.

3. The method for producing single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide according to claim 1, characterized in that: The ball milling device in step (2) is a horizontal ball mill with a rotation speed of 60-80 r / min.

4. The method for producing single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide according to claim 1, characterized in that: The mass ratio of material A to lithium nickel cobalt manganese oxide in step (3) is (0.5-1.5):1000.

5. The method for producing single crystal lithium manganese oxide coated with nickel cobalt lithium manganese oxide according to claim 1, characterized in that: In the step (5), the sintering temperature is 300-650°C and the sintering time is 4-8 hours.

6. Use of the coating material of single-crystal lithium manganate coated with nickel cobalt manganate obtained by the production method of the coating material of single-crystal lithium manganate coated with nickel cobalt manganate as described in any one of claims 1 to 5 in battery positive electrode materials.

Images