Lithium nickel cobalt manganese oxide positive electrode material, and preparation method and application thereof

Abstract

The application relates to the technical field of material preparation, and discloses a nickel-cobalt-lithium manganate positive electrode material, a preparation method and application thereof. The nickel-cobalt-lithium manganate positive electrode material comprises a core, a first coating layer and a second coating layer. The first coating layer is between the core and the second coating layer. The chemical formula of the material in the core is LiNi x Co y Mn z M (1‑x‑y‑z) O2, the chemical formula of the material in the first coating layer is LiNi i Co j Mn k N (1‑i‑j‑k) O2, and the material in the second coating layer is an oxide. The preparation method of the nickel-cobalt-lithium manganate positive electrode material comprises steps (I) of preparing various precursors and (II) of coating. The secondary particle size of the nickel-cobalt-lithium manganate positive electrode material is small, the specific surface area is small, the material structure is stable, and the material has high rate, high capacity and energy and long cycle performance under high voltage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, in particular to a lithium nickel cobalt manganese oxide positive electrode material, and a preparation method and application thereof. BACKGROUND

[0002] With the gradual elimination of fuel vehicles by new energy vehicles, the new energy industry is growing rapidly, but the gradual use of new energy vehicles finds that the mileage of new energy vehicles cannot meet the needs of customers. In order to solve the mileage problem of new energy vehicles, a secondary battery with high energy, good rate performance, low price and safety performance is urgently needed, which can realize fast charging like refueling. Correspondingly, a positive electrode material with performance meeting the above requirements is needed, among which the nickel cobalt manganese ternary material has been widely concerned due to its high capacity, high power, long cycle life, low toxicity and low cost.

[0003] The main development direction of nickel cobalt manganese ternary material is three, the first is high-capacity represented by high-nickel, but the structure of the material is unstable, and the cycle performance and safety are poor; the second is high-voltage represented by low-nickel, but the theoretical specific capacity of the material is relatively low; the third is high-power. However, high-power nickel cobalt manganese ternary material has many shortcomings: first, the electronic conductivity is low, the specific capacity of large-rate charging and discharging is low; second, the material is polycrystalline, the charging voltage of the material is low, and the capacity of the material is low; third, the cobalt content is high, and the cost is high.

[0004] In order to solve the problems of low discharge capacity and high cost of the current high-power nickel cobalt manganese ternary material, a new lithium nickel cobalt manganese oxide positive electrode material is provided to promote the healthy and long-term development of new energy. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide a lithium nickel cobalt manganese oxide positive electrode material, and a preparation method and application thereof, which has small secondary particle size, small specific surface area, stable material structure, and high rate, high capacity, energy and long cycle performance at high voltage.

[0006] To achieve the above purpose, the first aspect of the present application provides a lithium nickel cobalt manganese oxide positive electrode material, which comprises a core, a first coating layer and a second coating layer. The first coating layer is between the core and the second coating layer. The chemical formula of the material in the core is LiNi x Co y Mn z M (1-x-y-z) O2, the chemical formula of the material in the first coating layer is LiNi i Co j Mn k N (1-i-j-k)O2, the material in the second coating layer is an oxide. Wherein, 0.55 < x ≤ 0.90, 0 < y ≤ 0.15, 0 < z ≤ 0.35, x + y + z < 1, x > i, 0.40 < i ≤ 0.70, 0 < j ≤ 0.40, 0 < k ≤ 0.30, i + j + k < 1, M and N are each independently at least one of Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si and W.

[0007] The nickel cobalt lithium manganate-based positive electrode material of the present application comprises a high-nickel and doped nickel cobalt lithium manganate core, a low-nickel and doped nickel cobalt lithium manganate coating layer and an oxide outer coating layer. The high-nickel and doped nickel cobalt lithium manganate core can make the material have a higher capacity. The low-nickel and doped nickel cobalt lithium manganate coating layer can reduce the specific surface area of the core material, thereby reducing the contact area of the core material with the electrolyte to reduce the probability of side reactions, and can inhibit the volume expansion of the core material during charging and discharging, and improve the loss of active material due to material fragmentation. The first coating layer has a relatively stable crystal structure, can remain stable at high voltage and reduce the activity of reaction with the electrolyte, and can improve the capacity and cycle performance of the material. The oxide outer coating layer can also remain stable at high voltage and reduce the activity of reaction with the electrolyte, and can improve the capacity and cycle performance of the material. Therefore, the nickel cobalt lithium manganate-based positive electrode material of the present application still has high rate, high capacity, energy and long cycle performance at high voltage.

[0008] In some embodiments, the oxide is an oxide of at least one element of Zr, Ni, Al, Cu, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and W.

[0009] In some embodiments, the mass of the first coating layer is greater than 0 and less than or equal to 20% and the mass of the second coating layer is greater than 0 and less than or equal to 1%, based on the sum of the masses of the core, the first coating layer and the second coating layer being 100%.

[0010] In some embodiments, the thickness of the first coating layer is 0.1 μm to 0.6 μm and the thickness of the second coating layer is greater than 0 nm and less than or equal to 20 nm.

[0011] In some embodiments, the core has a polycrystalline structure that is spheroid-like.

[0012] In some embodiments, the primary particle size of the core is 0.5 μm to 1.0 μm.

[0013] In some embodiments, the secondary particle size of the core is 1.5 μm to 3.0 μm.

[0014] In some embodiments, the average particle size is 2.0 μm to 3.0 μm.

[0015] In some embodiments, the specific surface area is 0.5 m 2 / g to 0.9 m 2 / g.

[0016] The second aspect of the present application provides a preparation method of a lithium nickel cobalt manganese oxide positive electrode material, comprising the steps of (I) preparing each precursor and (II) coating.

[0017] Step (I) for preparing each precursor: mix the nickel source, manganese source and cobalt source according to the formula amount, then add the complexing agent and the precipitating agent to react, and then perform solid-liquid separation, take the solid phase to obtain the inner core precursor A; mix the nickel source, manganese source and cobalt source according to the formula amount, then add the complexing agent and the precipitating agent to react, and then perform solid-liquid separation, take the solid phase to obtain the precursor B, and then perform first crushing to obtain the coated precursor C.

[0018] Step (II) coating: mix the inner core precursor A with the lithium source and the first dopant, perform first sintering and second crushing to obtain the inner core, then mix the coated precursor C and the second dopant, perform second sintering and third crushing, and then mix with the coating agent to perform third sintering.

[0019] The preparation method of the lithium nickel cobalt manganese oxide positive electrode material has the following technical effects:

[0020] Firstly, mixing, sintering and crushing the inner core precursor A with the lithium source and the first dopant can obtain a spherical polycrystalline structure inner core with small particle size and fast lithium ion transmission speed, which can realize high capacity at high rate.

[0021] Secondly, by separately preparing the inner core precursor A and the coated precursor C, the solid phase coating method can in-situ grow a relatively low-nickel doped lithium nickel cobalt manganese oxide coating layer on the surface of the polycrystalline structure inner core. This coating layer can reduce the specific surface area of the inner core material, thereby reducing the contact area between the inner core material and the electrolyte to reduce the probability of side reactions, inhibiting the volume expansion of the inner core material during charging and discharging, and improving the loss of active material due to material fragmentation. The low-nickel coating layer has a relatively stable crystal structure, can maintain stability at high voltage and reduce the activity of reaction with the electrolyte, and can improve the capacity and cycle performance of the material. Compared with the method of directly preparing two components of core-shell structure and then coating, the solid phase in-situ coating method used in the present application has a polycrystalline, high-nickel lithium nickel cobalt manganese oxide as the inner core and a low-nickel lithium nickel cobalt manganese oxide as the outer part. During the sintering process, the components will not be homogenized and the overall morphology will be polycrystalline, and a core-shell structure with better performance can be obtained. Compared with the liquid phase coating, the solid phase in-situ coating method used in the present application will not cause a large amount of lithium ions to be removed from the high-nickel material during the coating process, resulting in the loss of active lithium. This preparation method is simple, practical and suitable for industrial production.

[0022] Thirdly, in the first mixing process (and the mixing process of the core precursor A), all the lithium source is added, which can increase the molar ratio of lithium and metal when the first sintering is performed, and reduce the mixing of lithium and nickel elements in the material, so that the core material with complete internal structure can be obtained. The excess lithium is uniformly distributed between the polycrystalline lattices and the surface of the core material, and reacts with the coated precursor C obtained by the first crushing to grow a relatively low-nickel coating layer on the surface of the polycrystalline core material in situ. This lithium addition method is beneficial to the close contact between the material in the core and the material in the first coating layer, and is beneficial to reducing the residual lithium on the surface of the prepared positive electrode material. This lithium addition method can make the prepared positive electrode material have less lithium-nickel mixing, low powder resistivity of the material and more active lithium, thereby improving the rate capability and cycle performance.

[0023] Fourthly, other elements are doped in the preparation of the core and the coating layer, which can stabilize the crystal structure inside the material and reduce the internal defects of the material, and finally the stable oxide is coated and sintered, which can improve the internal stress of the material and stabilize the surface layer structure of the material, so that the lithium nickel cobalt manganese oxide-based positive electrode material with high voltage, high rate, high capacity and long cycle can be prepared.

[0024] In some embodiments, the Dv50 of the core precursor A is 1.5 μm to 3.0 μm.

[0025] In some embodiments, the Dv50 of the precursor B is 1.0 μm to 2.0 μm.

[0026] In some embodiments, the Dv50 of the coated precursor C is 0.5 μm to 1.0 μm.

[0027] In some embodiments, the nickel source is at least one of nickel sulfate, nickel chloride and nickel nitrate.

[0028] In some embodiments, the cobalt source is at least one of cobalt sulfate, cobalt chloride and cobalt nitrate.

[0029] In some embodiments, the manganese source is at least one of manganese sulfate, manganese chloride and manganese nitrate.

[0030] In some embodiments, the lithium source is at least one of LiOH, Li2CO3 and CH3COOLi.

[0031] In some embodiments, the molar ratio of the sum of lithium in the lithium source and metal elements in the core precursor A is (1.10-1.30):1.

[0032] In some embodiments, the first dopant and the second dopant are each independently selected from the oxide of at least one element selected from Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si and W.

[0033] In some embodiments, the coating agent is an oxide of at least one element selected from Zr, Ni, Al, Cu, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and W.

[0034] In some embodiments, the precipitating agent is an alkali solution.

[0035] In some embodiments, the complexing agent is ammonia water.

[0036] In some embodiments, the first sintering has a maximum temperature of 700-800℃ and a time of 3-9h.

[0037] In some embodiments, the first sintering is performed under oxygen flow and employs a stepwise temperature increase at a rate of 2-10℃ / min.

[0038] In some embodiments, the second sintering has a maximum temperature of 800-900℃ and a time of 4-12h.

[0039] In some embodiments, the second sintering is performed under oxygen flow and employs a stepwise temperature increase at a rate of 2-10℃ / min.

[0040] In some embodiments, the third sintering has a maximum temperature of 400-700℃ and a time of 2-8h.

[0041] In some embodiments, the third sintering is performed under oxygen flow and employs a stepwise temperature increase at a rate of 2-10℃ / min.

[0042] In some embodiments, the first pulverization employs an air flow pulverizer.

[0043] In some embodiments, the second pulverization comprises sequentially pulverizing the solid obtained after the first sintering using a rotary wheel mill and a mechanical pulverizer.

[0044] In some embodiments, the third pulverization employs a mechanical pulverizer.

[0045] The present application also provides a use of the nickel-cobalt-lithium manganate positive electrode material in a positive electrode material. The nickel-cobalt-lithium manganate positive electrode material can be used as a positive active material to meet the use requirements of new energy vehicle fast charging. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 FIG. 1 is a structural schematic diagram of the nickel-cobalt-lithium manganate positive electrode material of the present application.

[0047] Figure 2The image shows the XRD test results of the lithium nickel cobalt manganese oxide cathode material in Example 1.

[0048] Figure 3 The graph shows the magnification test results for the examples and comparative examples 1 to 3. Detailed Implementation

[0049] The lithium nickel cobalt manganese oxide cathode material of this invention refers to a lithium transition metal composite oxide containing nickel, cobalt, and manganese, which can be used as a cathode active material in secondary batteries. It can be used alone or in combination with other cathode active materials (such as lithium iron phosphate cathode materials, lithium cobalt oxide cathode materials, lithium nickel cobalt aluminum oxide cathode materials, lithium manganese oxide cathode materials, etc.).

[0050] like Figure 1 As shown, the lithium nickel cobalt manganese oxide (LCO) cathode material includes a core 10, a first coating layer 30, and a second coating layer 50. The first coating layer 30 is located between the core 10 and the second coating layer 50, i.e., from the inside out, the core 10, the first coating layer 30, and the second coating layer 50 are arranged sequentially. The average particle size of the LCO cathode material is 2.0 μm to 3.0 μm. As an example, the average particle size of the LCO cathode material may be, but is not limited to, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, and 3.0 μm. The specific surface area is 0.5 m². 2 / g to 0.9m 2 / g, as an example, the specific surface area may be, but is not limited to, 0.5m². 2 / g, 0.55m 2 / g, 0.6m 2 / g, 0.65m 2 / g, 0.7m 2 / g, 0.75m 2 / g, 0.8m 2 / g, 0.85m 2 / g, 0.9m 2 / g.

[0051] The chemical formula of the material in the core is LiNi. x Co y Mn z M (1- x - y - z)02, wherein 0.55 < x < 0.90, 0 < y < 0.15, 0 < z < 0.35, x + y + z < 1, M is at least one of Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si, and W. In some embodiments, M can be at least one of Zr, Mg, Sr, Al, Y, B, and W. As an example, M can be Zr or W. As an example, x is 0.646, y is 0.10, and z is 0.25. The core is a spheroid-like polycrystalline structure with small particle size and fast lithium ion transport speed, which can achieve high capacity at high rate. The primary particle size of the core is 0.5 pm to 1.0 pm, and as an example, the primary particle size can be, but is not limited to, 0.5 pm, 0.6 pm, 0.7 pm, 0.8 pm, 0.9 pm, 1.0 pm. The secondary particle size of the core is 1.5 pm to 3.0 pm, and as an example, the secondary particle size can be, but is not limited to, 1.5 pm, 1.6 pm, 1.7 pm, 1.8 pm, 1.9 pm, 2.0 pm, 2.1 pm, 2.2 pm, 2.3 pm, 2.4 pm, 2.5 pm, 2.6 pm, 2.7 pm, 2.8 pm, 2.9 pm, 3.0 pm.

[0052] The chemical formula of the material in the first coating layer is LiNi i Co j Mn k N (1-i-j-k) 02, wherein x > i, 0.40 < i < 0.70, 0 < j < 0.40, 0 < k < 0.30, i + j + k < 1, N is at least one of Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si, and W. In some embodiments, N can be at least one of Zr, Mg, Sr, Al, Y, B, and W. As an example, N can be Zr or W. As an example, i is 0.495, j is 0.20, and k is 0.30. The mass of the first coating layer is greater than 0 and less than or equal to 20%, and as an example, the mass of the first coating layer can be, but is not limited to, 0.0005%, 0.001%, 0.1%, 0.5%, 1%, 2%, 5%, 7%, 10%, 12%, 15%, 17%, 20%, based on the sum of the masses of the core, the first coating layer, and the second coating layer being 100%. The thickness of the first coating layer is 0.1 pm to 0.6 pm, and as an example, the thickness can be, but is not limited to, 0.1 pm, 0.2 pm, 0.3 pm, 0.4 pm, 0.5 pm, 0.6 pm.

[0053] The material in the second coating layer is an oxide, and the oxide is an oxide of at least one element in Zr, Ni, Al, Cu, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and W. As an example, the oxide is ZrO2, NiO, Al2O3, CuO, Co3O4, SrO, MnO2, Y2O3, TiO2, MgO, MoO2, B2O3, SnO2, Fe2O3, ZnO, SiO2, or WO3. The mass of the second coating layer is greater than 0 and less than or equal to 1%, and as an example, the mass of the second coating layer can be, but is not limited to, 0.0005%, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 0.7%, 1%. The thickness of the second coating layer is greater than 0 nm and less than or equal to 20 nm. As an example, the thickness can be, but is not limited to, 0.1 nm, 0.3 nm, 0.5 nm, 1 nm, 3 nm, 5 nm, 7 nm, 10 nm, 11 nm, 13 nm, 15 nm, 17 nm, 19 nm, 20 nm.

[0054] The preparation method of the nickel-cobalt-manganese lithium acid positive electrode material of the present application comprises steps (I) of preparing each precursor and (II) of coating.

[0055] Step (I) of preparing each precursor comprises: mixing nickel source, manganese source, and cobalt source according to the formula amount, then adding complexing agent and precipitating agent to react, and then performing solid-liquid separation to obtain core precursor A; mixing nickel source, manganese source, and cobalt source according to the formula amount, then adding complexing agent and precipitating agent to react, and then performing solid-liquid separation to obtain precursor B; and then performing first crushing to obtain coated precursor C.

[0056] In step (I) of preparing each precursor, as an example, the nickel source is at least one of nickel sulfate, nickel chloride, and nickel nitrate, the cobalt source is at least one of cobalt sulfate, cobalt chloride, and cobalt nitrate, and the manganese source is at least one of manganese sulfate, manganese chloride, and manganese nitrate.

[0057] The nickel source, the manganese source, and the cobalt source can be added in the form of their corresponding aqueous solutions, and the solution concentration can be used to control the granulation speed of the crystal grains, and by setting a suitable concentration, it is beneficial for the full contact of each metal raw material to generate the crystal nucleus of the core precursor crystal grain. The nickel source, the manganese source, and the cobalt source are added to a reaction kettle, first undergo complexing reaction with the complexing agent, and then undergo coprecipitation reaction with the precipitating agent to generate a nickel-cobalt-manganese ternary precursor compound. The complexing agent can be, but is not limited to, ammonia water, and the precipitating agent can be, but is not limited to, lye, and specifically can be, but is not limited to, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate.

[0058] The Dv50 of the inner core precursor A can be adjusted by the concentration of the nickel source, the manganese source, the cobalt source, the complexing agent and the precipitant, and the reaction conditions. The Dv50 of the inner core precursor A of the present application is 1.5 μm to 3.0 μm, and specifically can be, but is not limited to, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm.

[0059] Similarly, the preparation process of the precursor B is similar to that of the inner core precursor A. The Dv50 of the precursor B is 1.0 μm to 2.0 μm, and specifically can be, but is not limited to, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm. The precursor B is further crushed by a first crushing to obtain a coated precursor C with a Dv50 of 0.5 μm to 1.0 μm. The first crushing uses an air jet crusher to crush the precursor B into finer particles, which is beneficial to improve the coating performance. The preparation of the precursor of the present application can use a conventional nickel-cobalt-manganese ternary precursor preparation, which is not the focus of the present application, and therefore will not be described here.

[0060] The step (II) of coating comprises: mixing the inner core precursor A with a lithium source and a first dopant, performing first sintering and second crushing to obtain an inner core, then adding the coated precursor C and a second dopant, performing second sintering and third crushing, and then mixing with a coating agent and performing third sintering.

[0061] As an example, the lithium source is at least one of LiOH, Li2CO3 and CH3COOLi. The molar ratio of lithium in the lithium source to the sum of metal elements in the inner core precursor A is (1.10-1.30):1.

[0062] As an example, the first dopant is selected from oxides of at least one element of Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si and W. As an example, the first dopant can be at least one of ZrO2, Al2O3, SrO, Y2O3, TiO2, MgO, MoO2, B2O3, SnO2, Fe2O3, SiO2 and WO3.

[0063] As an example, the first sintering has a maximum temperature of 700-800°C, specifically but not exclusively 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800°C. The first sintering has a time of 3-9h, specifically but not exclusively 3, 4, 5, 6, 7, 8, 9h. The first sintering is performed under oxygen flow and uses a stepwise temperature increase with a ramp rate of 2-10°C / min. As an example, the first sintering process is: oxygen flow, temperature increase to 300-600°C at a ramp rate of 2-10°C / min and holding for 4-6h, temperature increase to 700-800°C at a ramp rate of 2-10°C / min and holding for 3-9h. After holding, natural cooling to room temperature is performed to obtain a black block material.

[0064] As an example, the second pulverization includes sequentially pulverizing the solid obtained after the first sintering using a rotary wheel mill and a mechanical pulverizer. Through this pulverization method, the material can be broken to a particle size Dv50 of 1.5-3.0μm, thereby obtaining a polycrystalline material core with a doping element in the crystal, excess lithium between the crystals, and on the surface of the crystals.

[0065] As an example, the second dopant is selected from oxides of at least one element of Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si, and W, specifically but not exclusively at least one of ZrO2, Al2O3, SrO, Y2O3, TiO2, MgO, MoO2, B2O3, SnO2, Fe2O3, SiO2, and WO3. The first and second dopants can be the same or different.

[0066] As an example, the second sintering has a maximum temperature of 800-900°C, specifically but not exclusively 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900°C. The second sintering has a time of 4-12h, specifically but not exclusively 4, 5, 6, 7, 8, 9, 10, 11, 12h. The second sintering is performed under oxygen flow and uses a stepwise temperature increase with a ramp rate of 2-10°C / min. As an example, the second sintering process is: oxygen flow, temperature increase to 400-600°C at a ramp rate of 2-10°C / min and holding for 3-6h, temperature increase to 800-900°C at a ramp rate of 2-10°C / min and holding for 4-12h. After holding, natural cooling to room temperature is performed to obtain a black block material.

[0067] As an example, the third pulverization is performed by using a mechanical pulverizer. By this pulverization method, the material can be broken to a particle size Dv50 of 2.0 μm to 4.5 μm, so as to obtain the core material coated by the coated precursor C.

[0068] As an example, the coating agent is an oxide of at least one element selected from Zr, Ni, Al, Cu, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and W. ZrO2, NiO, Al2O3, CuO, Co3O4, SrO, MnO2, Y2O3, TiO2, MgO, MoO2, B2O3, SnO2, Fe2O3, ZnO, SiO2or WO3.

[0069] As an example, the highest temperature of the third sintering is 400℃ to 700℃, and specifically but not exclusively 400℃, 430℃, 450℃, 480℃, 500℃, 550℃, 570℃, 600℃, 650℃, 700℃.

[0070] The time of the third sintering is 2h to 8h, and specifically but not exclusively 2h, 3h, 4h, 5h, 6h, 7h, 8h.

[0071] The third sintering is performed under oxygen flow, and the heating rate is 2℃ / min to 10℃ / min. As an example, the process of the third sintering is: oxygen is flowed in, and the temperature is raised to 400℃ to 700℃ at a heating rate of 2℃ / min to 10℃ / min and kept for 2h to 8h. After keeping, it is naturally cooled to room temperature, so as to obtain the lithium nickel cobalt manganese oxide-based positive electrode material.

[0072] In order to better illustrate the purpose, technical scheme and beneficial effects of the present application, the present application will be further described below in combination with specific examples. It should be noted that the following described method is a further explanation and description of the present application, and should not be regarded as a limitation of the present application.

[0073] Example 1

[0074] The chemical formula of the core material in the lithium nickel cobalt manganese oxide-based positive electrode material of the present example is LiNi 0.646 Co 0.10 Mn 0.25 Zr 0.002 W 0.002 O2, and the chemical formula of the material in the first coating layer is LiNi 0.494 Co 0.20 Mn 0.30 Al 0.004 Zr 0.002O2, and the coating agent of the second coating layer is Al2O3 and TiO2 (mass ratio of 1:1). The mass of the first coating layer is 5%, and the mass of the second coating layer is 0.5%, based on the sum of the masses of the core, the first coating layer and the second coating layer being 100%.

[0075] The preparation method of the nickel-cobalt-manganese lithium manganate-based positive electrode material of the embodiment comprises the following steps:

[0076] (I) Preparation of each precursor

[0077] Nickel nitrate, cobalt chloride and manganese nitrate were mixed according to the formula amount, and then ammonia water and sodium hydroxide were added and reacted, followed by solid-liquid separation. The solid phase was obtained to obtain the core precursor A (Dv50 is 2.0 μm);

[0078] Nickel nitrate, cobalt chloride and manganese nitrate were mixed according to the formula amount, and then ammonia water and sodium hydroxide were added and reacted, followed by solid-liquid separation. The solid phase was obtained to obtain the core precursor A (Dv50 is 2.0 μm);

[0079] (II) Coating

[0080] The core precursor A, lithium hydroxide (the molar ratio of lithium to the sum of nickel, cobalt and manganese in the core precursor A is 1.2:1), ZrO2 and WO2 were mixed, and sintering was performed under oxygen condition at a heating rate of 5 ℃ / min, and the temperature was raised to 430 ℃ and kept for 4 h, and then the temperature was continuously raised to 750 ℃ for sintering, and kept for 6 h, and then the furnace was cooled to room temperature, and then a rotary wheel mill and a mechanical pulverizer were used for pulverization, and then a 300-mesh sieve was used for sieving, to obtain a spherical polycrystalline core material with Dv50 of 2.0 μm, and the primary particle size of the core is 0.7 μm and the secondary particle size is 1.6 μm;

[0081] The core material was mixed with the coating precursor C, ZrO2 and Al2O3, and sintering was performed under oxygen condition at a heating rate of 5 ℃ / min, and the temperature was raised to 500 ℃ and kept for 4 h, and then the temperature was continuously raised to 850 ℃ for sintering, and kept for 10 h, and then the furnace was cooled to room temperature, and then a mechanical pulverizer was used for pulverization and a 300-mesh sieve was used for sieving, to obtain the core material coated with the coating precursor C;

[0082] The core material coated with the coating precursor C was mixed with Al2O3 and TiO2, and sintering was performed under oxygen condition at a heating rate of 5 ℃ / min, and the temperature was raised to 480 ℃ and kept for 6 h, and then the temperature was cooled to room temperature, to obtain the nickel-cobalt-manganese lithium manganate-based positive electrode material. The nanomeasurer software detection showed that the thickness of the first coating layer is 0.3 μm, and the thickness of the second coating layer is 10 nm.

[0083] The prepared nickel-cobalt-manganese lithium manganate-based positive electrode material was subjected to XRD test, and the results are shown inFigure 2 As shown in the figure. Figure 2 It can be seen that it is consistent with the peak of the nickel-cobalt-manganese ternary positive electrode material, which shows that the prepared material is a nickel-cobalt-manganese ternary positive electrode material. The (006) / (102) and (108) / (110) crystal face peaks are obviously separated, which shows that both materials have high crystallinity. In addition, the (003) / (104) crystal face peak intensity ratio in the XRD is greater than 1.2, which shows that the prepared nickel-cobalt-manganese lithium acid system positive electrode material has a good layered crystal structure and a small amount of lithium-nickel mixing.

[0084] Example 2

[0085] The chemical formula of the core material in the nickel-cobalt-manganese lithium acid system positive electrode material of the present embodiment is LiNi 0.796 Co 0.10 Mn 0.10 Zr 0.002 W 0.002 O2, the chemical formula of the material in the first coating layer is LiNi 0.644 Co 0.15 Mn 0.20 Al 0.004 Zr 0.002 O2, and the coating agent of the second coating layer is Al2O3 and TiO2(mass ratio 1:1). Taking the sum of the mass of the core, the first coating layer and the second coating layer as 100%, the mass of the first coating layer is 5%, and the mass of the second coating layer is 0.5%.

[0086] The preparation method of the nickel-cobalt-manganese lithium acid system positive electrode material of the present embodiment comprises the following steps:

[0087] (I) Preparation of each precursor

[0088] According to the formula amount, nickel nitrate, cobalt chloride and manganese nitrate are mixed, then ammonia water and sodium hydroxide are added and reacted, and then solid-liquid separation is carried out. The solid phase is taken to obtain the core precursor A (Dv50 is 2.0 μm);

[0089] According to the formula amount, nickel nitrate, cobalt chloride and manganese nitrate are mixed, then ammonia water and sodium hydroxide are added and reacted, and then solid-liquid separation is carried out. The solid phase is taken to obtain the core precursor A (Dv50 is 2.0 μm);

[0090] (II) Coating

[0091] The core precursor A, lithium hydroxide (molar ratio of lithium to the sum of nickel, cobalt and manganese in the core precursor A is 1.2:1), ZrO2 and WO2 are mixed, sintering is performed under oxygen condition, the heating rate is 5℃ / min, the temperature is raised to 430℃, and the temperature is kept for 4h, then the temperature is continuously raised to 750℃ for sintering, and the temperature is kept for 6h, and then the furnace is cooled to room temperature, then a rotary wheel grinder and a mechanical crusher are used in sequence for crushing, and then the crushed product is passed through a 300 mesh sieve, to obtain a core material in a spherical shape, a polycrystal and Dv50 of 2.0μm, and the primary particle size of the core is 0.75μm and the secondary particle size is 1.7μm;

[0092] The core material is mixed with the coating precursor C, ZrO2 and Al2O3, sintering is performed under oxygen condition, the heating rate is 5℃ / min, the temperature is raised to 500℃, and the temperature is kept for 4h, then the temperature is continuously raised to 850℃ for sintering, and the temperature is kept for 6h, and then the furnace is cooled to room temperature, and then a mechanical crusher is used for crushing, and then the crushed product is passed through a 300 mesh sieve, to obtain the core material coated with the coating precursor C;

[0093] The core material coated with the coating precursor C is mixed with Al2O3 and TiO2, sintering is performed under oxygen condition, the temperature is raised to 450℃ at a heating rate of 5℃ / min, and the temperature is kept for 6h, and then the temperature is cooled to room temperature, to obtain the lithium nickel cobalt manganese oxide-based positive electrode material. The nanomeasurer software is used for detection, the thickness of the first coating layer is 0.3μm, and the thickness of the second coating layer is 10nm.

[0094] Example 3

[0095] The chemical formula of the core material in the lithium nickel cobalt manganese oxide-based positive electrode material of this example is LiNi 0.646 Co 0.10 Mn 0.25 Zr 0.002 W 0.002 O2, the chemical formula of the material in the first coating layer is LiNi 0.494 Co 0.20 Mn 0.30 Al 0.004 Zr 0.002 O2, and the coating agent of the second coating layer is Al2O3 and TiO2 (mass ratio of 1:1). The mass of the first coating layer is 10% and the mass of the second coating layer is 0.5% based on the sum of the masses of the core, the first coating layer and the second coating layer being 100%.

[0096] The preparation method of the lithium nickel cobalt manganese oxide-based positive electrode material of this example comprises the following steps:

[0097] (I) preparation of each precursor

[0098] According to the formula, take the mixed nickel nitrate, cobalt chloride, manganese nitrate, then add ammonia and sodium hydroxide, and then perform solid-liquid separation after reaction, take the solid phase to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0099] According to the formula, take the mixed nickel nitrate, cobalt chloride, manganese nitrate, then add ammonia and sodium hydroxide, and then perform solid-liquid separation after reaction, take the solid phase to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0100] (II) Coating

[0101] Mix the inner core precursor A, lithium hydroxide (the molar ratio of lithium to the sum of nickel, cobalt and manganese in the inner core precursor A is 1.2:1), ZrO2 and WO2, and perform sintering under oxygen condition, the heating rate is 5 ℃ / min, heat to 430 ℃, keep for 4 h, continue to heat to 800 ℃ for sintering, keep for 6 h, then cool to room temperature, then use the rotary wheel mill and mechanical crusher for crushing, and pass through a 300 mesh sieve, to obtain the inner core material with a spherical shape, a polycrystalline and a Dv50 of 2.0 μm, and a primary particle size of 0.5 μm and a secondary particle size of 1.5 μm;

[0102] Add the coating precursor C, ZrO2 and Al2O3 to the inner core material, mix, and perform sintering under oxygen condition, the heating rate is 5 ℃ / min, heat to 500 ℃, keep for 4 h, continue to heat to 850 ℃ for sintering, keep for 10 h, then cool to room temperature, then use the mechanical crusher for crushing and pass through a 300 mesh sieve, to obtain the inner core material coated by the coating precursor C;

[0103] Mix the inner core material coated by the coating precursor C, Al2O3 and TiO2, and perform sintering under oxygen condition, heat to 480 ℃ at a heating rate of 5 ℃ / min, keep for 6 h, and cool to room temperature, to obtain the lithium nickel cobalt manganese oxide positive electrode material. The nanomeasurer software detection shows that the thickness of the first coating layer is 0.5 μm, and the thickness of the second coating layer is 10 nm.

[0104] Example 4

[0105] The chemical formula of the inner core material in the lithium nickel cobalt manganese oxide positive electrode material of the example is LiNi 0.646 Co 0.10 Mn 0.25 Al 0.004 O2, the chemical formula of the material in the first coating layer is LiNi 0.494 Co 0.20 Mn 0.30 Mg 0.003 Ti 0.003O2, and the coating agent of the second coating layer is ZrO2 and MgO (mass ratio of 2:1). The mass of the first coating layer is 5%, and the mass of the second coating layer is 0.5%, based on the sum of the masses of the core, the first coating layer and the second coating layer being 100%.

[0106] The preparation method of the lithium nickel cobalt manganese oxide-based positive electrode material of the embodiment comprises the following steps:

[0107] (I) Preparation of each precursor

[0108] According to the formula amount, nickel chloride, cobalt chloride and manganese chloride are mixed, then ammonia water and sodium hydroxide are added and reacted, followed by solid-liquid separation, and the solid phase is taken to obtain the core precursor A (Dv50 is 2.0 μm);

[0109] According to the formula amount, nickel nitrate, cobalt nitrate and manganese nitrate are mixed, then ammonia water and sodium hydroxide are added and reacted, followed by solid-liquid separation, and the solid phase is taken to obtain the precursor B (Dv50 is 1.5 μm), which is then crushed by a jet mill to obtain the coated precursor C (Dv50 is 1.0 μm);

[0110] (II) Coating

[0111] The core precursor A, lithium hydroxide (the molar ratio of lithium to the sum of nickel, cobalt and manganese in the core precursor A is 1.2:1), and Al2O3 are mixed, and sintering is performed under oxygen condition at a heating rate of 5 ℃ / min, the temperature is raised to 430 ℃, and the temperature is kept for 4 h, then the temperature is continuously raised to 750 ℃ for sintering, and the temperature is kept for 6 h, and then the furnace is cooled to room temperature, and then a rotary wheel mill and a mechanical crusher are used for crushing, and then the crushed product is sieved through a 300-mesh sieve, to obtain a spherical polycrystalline core material with Dv50 of 2.0 μm, and the primary particle size of the core is 0.6 μm, and the secondary particle size is 1.6 μm;

[0112] The coated precursor C, MgO and TiO2 are added to the core material, and sintering is performed under oxygen condition at a heating rate of 5 ℃ / min, the temperature is raised to 500 ℃, and the temperature is kept for 4 h, then the temperature is continuously raised to 850 ℃ for sintering, and the temperature is kept for 10 h, and then the furnace is cooled to room temperature, and then a mechanical crusher is used for crushing, and then the crushed product is sieved through a 300-mesh sieve, to obtain the core material coated by the coated precursor C;

[0113] The core material coated by the precursor C and ZrO2 and MgO are mixed, and sintering is performed under oxygen condition at a heating rate of 5 ℃ / min, the temperature is raised to 480 ℃, and the temperature is kept for 6 h, and then the temperature is cooled to room temperature, to obtain the lithium nickel cobalt manganese oxide-based positive electrode material. The nanomeasurer software detection shows that the thickness of the first coating layer is 0.25 μm, and the thickness of the second coating layer is 10 nm.

[0114] Example 5

[0115] The chemical formula of the core material in the nickel cobalt lithium manganate-based positive electrode material of the embodiment is LiNi 0.646 Co 0.10 Mn 0.25 Zr 0.002 W 0.002 O2, the chemical formula of the material in the first coating layer is LiNi 0.494 Co 0.20 Mn 0.30 Al 0.004 Zr 0.002 O2, and the coating agent of the second coating layer is Al2O3 and TiO2 (mass ratio of 1:1). The mass of the first coating layer is 5% and the mass of the second coating layer is 0.5% based on the sum of the masses of the core, the first coating layer and the second coating layer being 100%.

[0116] The preparation method of the nickel cobalt lithium manganate-based positive electrode material of the embodiment comprises the following steps:

[0117] (I) Preparation of each precursor

[0118] Nickel nitrate, cobalt chloride and manganese nitrate were mixed according to the formula amount, and then ammonia water and sodium hydroxide were added and reacted, followed by solid-liquid separation. The solid phase was obtained to obtain the core precursor A (Dv50 is 2.0 μm);

[0119] Nickel nitrate, cobalt chloride and manganese nitrate were mixed according to the formula amount, and then ammonia water and sodium hydroxide were added and reacted, followed by solid-liquid separation. The solid phase was obtained to obtain the core precursor A (Dv50 is 2.0 μm);

[0120] (II) Coating

[0121] The core precursor A, CH3COOLi (the molar ratio of lithium to the sum of nickel, cobalt and manganese in the core precursor A is 1.3:1), ZrO2 and WO2 were mixed, and sintering was performed under oxygen condition. The heating rate was 5 ℃ / min, the temperature was raised to 430 ℃, and the temperature was kept for 4 h. The temperature was continuously raised to 750 ℃ for sintering, and the temperature was kept for 6 h. After the furnace was cooled to room temperature, a rotary wheel mill and a mechanical pulverizer were used for pulverization in sequence, and the mixture was sieved through a 300 mesh sieve. A polycrystalline core material with a spherical shape and a Dv50 of 2.0 μm was obtained. The primary particle size of the core was 0.5 μm, and the secondary particle size was 1.7 μm;

[0122] The core material was mixed with the coating precursor C, ZrO2 and Al2O3, and sintering was performed under oxygen condition. The heating rate was 5 ℃ / min, the temperature was raised to 500 ℃, and the temperature was kept for 4 h. The temperature was continuously raised to 850 ℃ for sintering, and the temperature was kept for 10 h. After the furnace was cooled to room temperature, a mechanical pulverizer was used for pulverization, and the mixture was sieved through a 300 mesh sieve. A core material coated with the coating precursor C was obtained;

[0123] The core material coated with precursor C and Al2O3 and TiO2 are mixed, and sintering is performed under oxygen condition, the temperature is raised to 480℃ at a temperature raising speed of 5℃ / min, and the temperature is kept for 6h, and then the temperature is cooled to room temperature, to obtain the nickel cobalt lithium manganate-based positive electrode material. The nanomeasurer software detection shows that the thickness of the first coating layer is 0.3μm, and the thickness of the second coating layer is 10nm.

[0124] Example 6

[0125] The chemical formula of the core material in the nickel cobalt lithium manganate-based positive electrode material of the present example is LiNi 0.646 Co 0.10 Mn 0.25 Zr 0.002 W 0.002 O2, the chemical formula of the material in the first coating layer is LiNi 0.494 Co 0.20 Mn 0.30 Al 0.004 Zr 0.002 O2, and the coating agent of the second coating layer is Al2O3 and TiO2(mass ratio is 1:1). The mass of the first coating layer is 5% and the mass of the second coating layer is 1.0% based on the sum of the mass of the core, the first coating layer and the second coating layer being 100%.

[0126] The preparation method of the nickel cobalt lithium manganate-based positive electrode material of the present example comprises the following steps:

[0127] (I) Preparation of each precursor

[0128] The nickel nitrate, cobalt chloride and manganese nitrate are mixed according to the formula amount, then ammonia water and sodium hydroxide are added and reacted, and then solid-liquid separation is performed, and the solid phase is taken to obtain the core precursor A(Dv50 is 2.5μm);

[0129] The nickel nitrate, cobalt chloride and manganese nitrate are mixed according to the formula amount, then ammonia water and sodium hydroxide are added and reacted, and then solid-liquid separation is performed, and the solid phase is taken to obtain the core precursor A(Dv50 is 2.5μm);

[0130] (II) Coating

[0131] The core precursor A, lithium hydroxide (molar ratio of lithium to the sum of nickel, cobalt and manganese in the core precursor A is 1.2:1), ZrO2 and WO2 are mixed, sintering is performed under oxygen condition, the heating rate is 3℃ / min, the temperature is raised to 430℃, and the temperature is kept for 4h, then the temperature is continuously raised to 750℃ for sintering, and the temperature is kept for 5h, and then the furnace is cooled to room temperature, then a rotary wheel mill and a mechanical crusher are used in sequence for crushing, and then the crushed product is passed through a 300 mesh sieve, to obtain a core material in a spherical shape, which is polycrystalline and has a Dv50 of 2.0μm, and the primary particle size of the core is 1.0μm and the secondary particle size is 1.9μm;

[0132] The core material is mixed with the coating precursor C, ZrO2 and Al2O3, sintering is performed under oxygen condition, the heating rate is 5℃ / min, the temperature is raised to 500℃, and the temperature is kept for 4h, then the temperature is continuously raised to 900℃ for sintering, and the temperature is kept for 10h, and then the furnace is cooled to room temperature, and then a mechanical crusher is used for crushing, and then the crushed product is passed through a 300 mesh sieve, to obtain the core material coated with the coating precursor C;

[0133] The core material coated with the coating precursor C is mixed with Al2O3 and TiO2, sintering is performed under oxygen condition, the temperature is raised to 550℃ at a heating rate of 5℃ / min, and the temperature is kept for 6h, and then the temperature is cooled to room temperature, to obtain the lithium nickel cobalt manganese oxide-based positive electrode material. The nanomeasurer software is used for detection, and the thickness of the first coating layer is 0.3μm and the thickness of the second coating layer is 15nm.

[0134] Comparative Example 1

[0135] The chemical formula of the core material in the lithium nickel cobalt manganese oxide-based positive electrode material of the present example is Li1Ni 0.646 Co 0.10 Mn 0.25 Zr 0.002 W 0.002 O2, the chemical formula of the material in the first coating layer is LiNi 0.494 Co 0.20 Mn 0.30 Al 0.004 Zr 0.002 O2, and the coating agent of the second coating layer is Al2O3 and TiO2 (mass ratio is 1:1). The mass of the first coating layer is 5% and the mass of the second coating layer is 0.5% based on the total mass of the core, the first coating layer and the second coating layer being 100%.

[0136] The preparation method of the lithium nickel cobalt manganese oxide-based positive electrode material of the present example comprises the following steps:

[0137] (I) Preparation of each precursor

[0138] According to the formula, take the mixed nickel nitrate, cobalt chloride, manganese nitrate, then add ammonia and sodium hydroxide, and then perform solid-liquid separation after reaction, take the solid phase to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0139] According to the formula, take the mixed nickel nitrate, cobalt chloride, manganese nitrate, then add ammonia and sodium hydroxide, and then perform solid-liquid separation after reaction, take the solid phase to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0140] (II) Coating

[0141] Mix the inner core precursor A, lithium hydroxide (here, the lithium hydroxide accounts for 90% of the total lithium hydroxide in mass, and the total lithium and the sum of nickel, cobalt and manganese in the inner core precursor A have a molar ratio of 1:1.2), ZrO2 and WO2, and perform sintering under oxygen condition, with a heating rate of 5 ℃ / min, heating to 430 ℃, keeping for 4 h, continuing to heat to 750 ℃ for sintering, keeping for 6 h, and then cooling to room temperature with the furnace, and then performing crushing with a rotary wheel mill and a mechanical crusher in turn, and passing through a 300 mesh sieve, to obtain a spherical polycrystalline inner core material with Dv50 of 2.0 μm, and the primary particle size of the inner core is 0.2 μm and the secondary particle size is 1.4 μm;

[0142] Add the coating precursor C, lithium hydroxide (here, the lithium hydroxide accounts for 10% of the total lithium hydroxide in mass), ZrO2 and Al2O3 to the inner core material, and mix, and perform sintering under oxygen condition, with a heating rate of 5 ℃ / min, heating to 500 ℃, keeping for 4 h, continuing to heat to 850 ℃ for sintering, keeping for 10 h, and then cooling to room temperature with the furnace, and then performing crushing with a mechanical crusher and passing through a 300 mesh sieve, to obtain the inner core material coated with the coating precursor C;

[0143] Mix the inner core material coated with the precursor C, Al2O3 and TiO2, and perform sintering under oxygen condition, with a heating rate of 5 ℃ / min, heating to 480 ℃, keeping for 6 h, and cooling to room temperature, to obtain a lithium nickel cobalt manganese oxide positive electrode material. The nanomeasurer software detection shows that the thickness of the first coating layer is 0-1.2 μm, and the thickness of the second coating layer is 10 nm.

[0144] Comparative Example 2

[0145] The chemical formula of the inner core material in the lithium nickel cobalt manganese oxide positive electrode material of the present example is LiNi 0.646 Co 0.10 Mn 0.25 Zr 0.002 W 0.002 O2, and the chemical formula of the material in the first coating layer is LiNi 0.494 Co 0.20 Mn0.30 Al 0.004 Zr 0.002 O2. With the sum of the core and the first coating layer's mass being 100%, the first coating layer's mass is 5%.

[0146] The preparation method of the lithium nickel cobalt manganese oxide cathode material in this embodiment includes the following steps:

[0147] (I) Preparation of various precursors

[0148] Nickel nitrate, cobalt chloride, and manganese nitrate were mixed according to the formula, and then ammonia and sodium hydroxide were added. After reaction, solid-liquid separation was carried out, and the solid phase was taken to obtain the core precursor A (Dv50 is 2.0 μm).

[0149] Nickel nitrate, cobalt chloride, and manganese nitrate were mixed according to the formula, and then ammonia and sodium hydroxide were added to react. After solid-liquid separation, the solid phase was taken to obtain precursor B (Dv50 is 1.5μm), which was then pulverized by an air jet mill to obtain coated precursor C (Dv50 is 1.0μm).

[0150] (II) Covering

[0151] The core precursor A, lithium hydroxide (the molar ratio of lithium to nickel, cobalt, and manganese in core precursor A is 1:1.2), ZrO2, and WO2 were mixed and sintered under oxygen conditions. The heating rate was 5℃ / min, and the temperature was raised to 430℃ and held for 4 hours. The temperature was then raised to 750℃ and held for 6 hours. After cooling to room temperature in the furnace, the material was pulverized by a rotary mill and a mechanical pulverizer, and then passed through a 300-mesh sieve to obtain a spherical polycrystalline core material with a Dv50 of 2.0 μm. The primary particle size of the core was 0.7 μm, and the secondary particle size was 1.6 μm.

[0152] The core material was then mixed with a coating precursor, C, ZrO2, and Al2O3. Sintering was performed under oxygen conditions at a heating rate of 5℃ / min, reaching 500℃ and holding for 4 hours. The temperature was then further increased to 850℃ and held for 10 hours before cooling to room temperature in the furnace. The resulting material was then pulverized using a mechanical pulverizer and passed through a 300-mesh sieve to obtain a lithium nickel cobalt manganese oxide cathode material. The thickness of the first coating layer was measured to be 0.3 μm using nanometer software.

[0153] Comparative Example 3

[0154] In this embodiment, the core material of the lithium nickel cobalt manganese oxide cathode material has the chemical formula LiNi. 0.446 Co 0.10 Mn 0.45 Zr 0.002 W 0.002 O2, the chemical formula of the material in the first coating layer is LiNi 0.394 Co0.20 Mn 0.40 Al 0.004 Zr 0.002 O2, the coating agent of the second coating layer is Al2O3 and TiO2 (mass ratio is 1:1). The mass of the first coating layer is 5%, and the mass of the second coating layer is 0.5%, based on the sum of the masses of the inner core, the first coating layer and the second coating layer being 100%.

[0155] The preparation method of the nickel-cobalt-manganese lithium acid positive electrode material of the embodiment comprises the following steps:

[0156] (I) Preparation of each precursor

[0157] According to the formula amount, nickel nitrate, cobalt chloride and manganese nitrate are mixed, then ammonia water and sodium hydroxide are added and reacted, followed by solid-liquid separation, and the solid phase is taken to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0158] According to the formula amount, nickel nitrate, cobalt chloride and manganese nitrate are mixed, then ammonia water and sodium hydroxide are added and reacted, followed by solid-liquid separation, and the solid phase is taken to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0159] (II) Coating

[0160] The inner core precursor A, lithium hydroxide (the molar ratio of lithium to the sum of nickel, cobalt and manganese in the inner core precursor A is 1.2:1), ZrO2 and WO2 are mixed, and sintering is carried out under oxygen condition, the heating rate is 5℃ / min, the temperature is raised to 430℃, and the temperature is kept for 4h, then the temperature is continuously raised to 750℃ for sintering, and the temperature is kept for 6h, then the furnace is cooled to room temperature, then a rotary wheel mill and a mechanical pulverizer are used for pulverization, and the mixture is passed through a 300 mesh sieve, to obtain a spherical polycrystalline inner core material with Dv50 of 2.0 μm, and the primary particle size of the inner core is 0.5 μm and the secondary particle size is 1.5 μm;

[0161] The inner core material is mixed with the coating precursor C, ZrO2 and Al2O3, and sintering is carried out under oxygen condition, the heating rate is 5℃ / min, the temperature is raised to 500℃, and the temperature is kept for 4h, then the temperature is continuously raised to 850℃ for sintering, and the temperature is kept for 10h, then the furnace is cooled to room temperature, then a mechanical pulverizer is used for pulverization, and the mixture is passed through a 300 mesh sieve, to obtain the inner core material coated with the coating precursor C;

[0162] The inner core material coated with the coating precursor C is mixed with Al2O3 and TiO2, and sintering is carried out under oxygen condition, the temperature is raised to 480℃ at a heating rate of 5℃ / min, and the temperature is kept for 6h, then the temperature is cooled to room temperature, to obtain the nickel-cobalt-manganese lithium acid positive electrode material. The nanomeasurer software detection shows that the thickness of the first coating layer is 0.3 μm, and the thickness of the second coating layer is 10 nm.

[0163] Comparative Example 4

[0164] The inner core material of the lithium nickel cobalt manganese oxide-based positive electrode material of the present example includes a high-nickel material and a low-nickel material, the chemical formula of the high-nickel material is LiNi 0.646 Co 0.10 Mn 0.25 Zr 0.002 W 0.002 O2, and the chemical formula of the low-nickel material is LiNi 0.494 Co 0.20 Mn 0.30 Al 0.004 Zr 0.002 O2, and the coating agent of the coating layer is Al2O3 and TiO2 (mass ratio of 1:1). The mass of the coating layer is 0.5% based on the sum of the mass of the inner core and the coating layer.

[0165] The preparation method of the lithium nickel cobalt manganese oxide-based positive electrode material of the present example includes the following steps:

[0166] (I) Preparation of each precursor

[0167] According to the formula amount, nickel nitrate, cobalt chloride and manganese nitrate are mixed, then ammonia water and sodium hydroxide are added and reacted, followed by solid-liquid separation, and the solid phase is taken to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0168] According to the formula amount, nickel nitrate, cobalt chloride and manganese nitrate are mixed, then ammonia water and sodium hydroxide are added and reacted, followed by solid-liquid separation, and the solid phase is taken to obtain the inner core precursor A (Dv50 is 2.0 μm);

[0169] (II) Coating

[0170] The precursor A, lithium hydroxide (90% of the total lithium hydroxide in terms of mass, and the molar ratio of the total lithium to the sum of nickel, cobalt and manganese in the inner core precursor A is 1.2:1), ZrO2 and WO2 are mixed, and sintering is carried out under oxygen condition, the heating rate is 5℃ / min, the temperature is raised to 430℃, and the temperature is kept for 4h, then the temperature is continuously raised to 750℃ for sintering, and the temperature is kept for 6h, then the furnace is cooled to room temperature, then a rotary wheel mill and a mechanical pulverizer are used for pulverization in turn, and the mixture is passed through a 300 mesh sieve, to obtain a first inner core material in the form of spherical polycrystals and with Dv50 of 2.0 μm;

[0171] The precursor C, lithium hydroxide (10% of the total lithium hydroxide by mass), ZrO2, and Al2O3 were mixed, and sintering was performed under oxygen conditions, with a temperature increase rate of 5°C / min, to 500°C, and holding for 4 h, and then to 850°C, and holding for 10 h, and then cooling to room temperature in the furnace, and then crushing by a mechanical crusher and passing through a 300 mesh sieve, to obtain a second inner core material;

[0172] The first inner core material, the second inner core material, and Al2O3 and TiO2 were mixed, and sintering was performed under oxygen conditions, with a temperature increase rate of 5°C / min, to 480°C, and holding for 6 h, and then cooling to room temperature, to obtain a lithium nickel cobalt manganese oxide-based positive electrode material. The thickness of the coating layer was 10 nm, as detected by nanomeasurer software.

[0173] The average particle size of the lithium nickel cobalt manganese oxide-based positive electrode materials of Examples 1 to 6 and Comparative Examples 1 to 4 was measured by a particle size analyzer, the specific surface area was measured by a Micromeritics surface area analyzer 3020, and the electrochemical performance was tested, and the results are shown in Table 1.

[0174] Electrochemical performance test: the lithium nickel cobalt manganese oxide-based positive electrode materials prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were used as active materials, mixed with a binder PVDF and a conductive agent (Super-P) in a mass ratio of 95:1.5:3.5, and an appropriate amount of N-vinyl pyrrolidone was added as a solvent to prepare a slurry, which was coated on an aluminum foil, and then vacuum dried and rolled to prepare a negative electrode sheet. A lithium metal was used as a counter electrode, a 1 mol / L LiPF6 and a three-component mixed solvent of EC:DMC:EMC = 1:1:1 (v / v) were mixed to form an electrolyte, a polypropylene microporous membrane was used as a separator, and a CR2032 type button cell was assembled in an inert gas glove box. The charge-discharge test of the button cell was performed on a battery test system of Wuhan Blue Electronic Co., Ltd. At 25°C, 0.1C constant current charging and discharging to 0.01V, then 0.02C constant current discharging to 0.005V, and finally 0.1C constant current charging to 4.45V. The capacity charged to 4.45V was the initial discharge specific capacity, the ratio of the discharge capacity to the charge capacity was the initial charge-discharge efficiency, and the corresponding 100th cycle discharge specific capacity was obtained after 100 cycles, and the 100th cycle charge-discharge efficiency was calculated.

[0175] The button cells prepared in Example 1 and Comparative Examples 1 to 3 were subjected to rate test, and the test conditions were as follows, and the results are shown in Table 2. Figure 3

[0176] Rate test: 0.33C charge-discharge for 2 times, and then 1C, 2C, 3C, 4C, and 5C under each rate condition for 50 cycles.

[0177] ​Electrochemical performance and physical performance of each example and comparative example in Table 1

[0178]

[0179] As can be seen from the results in Table 1, compared with Comparative Examples 1 to 4, the lithium nickel cobalt manganese oxide positive electrode material of Examples 1 to 6 has a small size, a small specific surface area, and a high first discharge specific capacity (≥198.5 mAh / g) and a high first charge-discharge efficiency (90.9%) at a high voltage of 4.45 V, indicating that the lithium nickel cobalt manganese oxide positive electrode material prepared has more lithium ions participating in the reaction and lithium ions being embedded and extracted back during the charge-discharge process, indicating that it has good kinetic performance and good rate performance. After 100 cycles, the material still has a high discharge specific capacity and charge-discharge efficiency, indicating that it has good cycle performance and less side reactions on the surface of the material.

[0180] Further combined Figure 3 It can be seen that the specific capacity of Example 1 is 187.9 mAh / g and 184.2 mAh / g at 1C and 5C rates, respectively, and the capacity retention rate after 237 cycles is 98.0%, which is higher than 92.7%, 97.3%, and 97.8% of Comparative Examples 1 to 3, indicating that the lithium nickel cobalt manganese oxide positive electrode material prepared in Example 1 has good rate and cycle performance.

[0181] In Comparative Example 1, the core precursor A and the coating precursor C are added with lithium source separately, and this lithium addition method is prone to lithium-nickel mixing, so the rate and cycle performance are not good.

[0182] In Comparative Example 2, no oxide is coated, and the core material is not protected, so the stability is not good, and it is difficult to inhibit the contact between the core material and the electrolyte, so there are side reactions, resulting in a decrease in electrochemical performance.

[0183] The core precursor A of Comparative Example 3 is a low-nickel material, and its capacity is low, especially the specific capacity of charge-discharge at high voltage and high rate, which is difficult to meet the fast charging use requirement.

[0184] In Comparative Example 4, the low-nickel lithium nickel cobalt manganese oxide positive electrode material and the high-nickel lithium nickel cobalt manganese oxide positive electrode material are mixed, and it is difficult to in-situ grow a relatively low-nickel doped lithium nickel cobalt manganese oxide coating layer on the surface of the polycrystalline structure core, so it is difficult to simultaneously exert the performance advantages of the low-nickel lithium nickel cobalt manganese oxide positive electrode material and the high-nickel lithium nickel cobalt manganese oxide positive electrode material.

[0185] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application, although the present application has been described in detail with reference to the preferred embodiments, but it is not limited to the examples listed in the embodiments, and those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A lithium nickel cobalt manganese oxide-based positive electrode material, characterized by, comprising a core, a first coating layer, and a second coating layer, the first coating layer being interposed between the core and the second coating layer, the material in the core having a chemical formula of LiNi x Co y Mn z M (1-x-y-z) O2, the material in the first coating layer having a chemical formula of LiNi i Co j Mn k N (1-i-j-k) O2, the material in the second coating layer being an oxide, wherein 0.55 < x ≤ 0.90, 0 < y ≤ 0.15, 0 < z ≤ 0.35, x + y + z < 1, x > i, 0.40 < i ≤ 0.70, 0 < j ≤ 0.40, 0 < k ≤ 0.30, i + j + k < 1, M and N are each independently at least one of Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si, and W, the primary particle size of the core is 0.5 μm to 1.0 μm, the secondary particle size of the core is 1.5 μm to 3.0 μm, the average particle diameter of the lithium nickel cobalt manganese oxide-based positive electrode material is 2.0 μm to 3.0 μm, the specific surface area of the lithium nickel cobalt manganese oxide-based positive electrode material is 0.5 m 2 / g to 0.9 m 2 / g, the oxide is an oxide of at least one element of Zr, Ni, Al, Cu, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and W, and the method for producing the lithium nickel cobalt manganese oxide-based positive electrode material comprises the steps of: (I) Preparation of each precursor The nickel source, manganese source and cobalt source are mixed according to the formula amount, then the complexing agent and the precipitant are added and reacted, and then solid-liquid separation is performed, and the solid phase is taken to obtain the inner core precursor A, The nickel source, manganese source and cobalt source are mixed according to the formula amount, then the complexing agent and the precipitant are added and reacted, and then solid-liquid separation is performed, and the solid phase is taken to obtain the inner core precursor A, (II) Coating The inner core precursor A is mixed with a lithium source and a first dopant, first sintering and second crushing are performed to obtain an inner core, then the coating precursor C and a second dopant are added and mixed, second sintering and third crushing are performed, and then a coating agent is added and mixed, third sintering is performed, and the coating agent is a material in the second coating layer.

2. The lithium nickel cobalt manganese oxide-based positive electrode material according to claim 1, characterized by, The mass of the first coating layer is greater than 0 and less than or equal to 20%, and the mass of the second coating layer is greater than 0 and less than or equal to 1%, based on the sum of the masses of the inner core, the first coating layer and the second coating layer being 100%. 3.The lithium nickel cobalt manganese oxide-based positive electrode material of claim 1, wherein, The thickness of the first coating layer is 0.1 μm to 0.6 μm, and the thickness of the second coating layer is greater than 0 nm and less than or equal to 20 nm. 4.The nickel cobalt manganese lithium-based positive electrode material of claim 1, wherein, The inner core is a spherical polycrystalline structure.

5. A method for producing a lithium nickel cobalt manganese oxide-based positive electrode material, characterized by, The lithium nickel cobalt manganese oxide cathode material comprises a core, a first coating layer, and a second coating layer, wherein the first coating layer is located between the core and the second coating layer, and the chemical formula of the material in the core is LiNi. x Co y Mn z M (1-x-y-z) O2, the chemical formula of the material in the first coating layer is LiNi i Co j Mn k N (1-i-j-k) O2, the material in the second coating layer is an oxide, wherein 0.55 < x ≤ 0.90, 0 < y ≤ 0.15, 0 < z ≤ 0.35, x + y + z < 1, x > i, 0.40 < i ≤ 0.70, 0 < j ≤ 0.40, 0 < k ≤ 0.30, i + j + k < 1, M and N are each independently at least one of Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si and W, and the oxide is an oxide of at least one element selected from Zr, Ni, Al, Cu, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and W, including the following steps: (I) Preparation of each precursor The nickel source, manganese source and cobalt source are mixed according to the formula amount, then the complexing agent and the precipitant are added and reacted, and then solid-liquid separation is performed, and the solid phase is taken to obtain the inner core precursor A, The nickel source, manganese source and cobalt source are mixed according to the formula amount, then the complexing agent and the precipitant are added and reacted, and then solid-liquid separation is performed, and the solid phase is taken to obtain the inner core precursor A, (II) Coating The inner core precursor A is mixed with a lithium source and a first dopant, first sintering and second crushing are performed to obtain an inner core, then the coating precursor C and a second dopant are added and mixed, second sintering and third crushing are performed, and then a coating agent is added and mixed, third sintering is performed, and the coating agent is a material in the second coating layer.

6. The method of claim 5, wherein the lithium nickel cobalt manganese oxide-based positive electrode material is prepared by the steps of: preparing a lithium nickel cobalt manganese oxide-based positive electrode material precursor; and performing a heat treatment on the lithium nickel cobalt manganese oxide-based positive electrode material precursor. At least one of the following features (1) to (20) is included: (1) The Dv50 of the inner core precursor A is 1.5 μm to 3.0 μm; (2) The Dv50 of the precursor B is 1.0 μm to 2.0 μm; (3) The Dv50 of the coating precursor C is 0.5 μm to 1.0 μm; (4) The nickel source is at least one of nickel sulfate, nickel chloride and nickel nitrate; (5) The cobalt source is at least one of cobalt sulfate, cobalt chloride and cobalt nitrate; (6) The manganese source is at least one of manganese sulfate, manganese chloride and manganese nitrate; (7) The lithium source is at least one of LiOH, Li2CO3 and CH3COOLi; (8) The molar ratio of lithium in the lithium source to metal elements in the inner core precursor A is (1.10~1.30):1; (9) The first dopant and the second dopant are each independently selected from oxides of at least one element selected from Zr, Al, Sr, Y, Ti, Mg, Mo, B, Sn, Fe, Si and W; (10) The precipitant is lye; (11) The complexing agent is ammonia water; (12) The highest temperature of the first sintering is 700°C to 800°C, and the time of the first sintering is 3h to 9h; (13) the first sintering is performed under oxygen flow and uses stepwise temperature rising, and the temperature rising rate is 2-10℃ / min; (14) the highest temperature of the second sintering is 800-900℃, and the time of the second sintering is 4-12h; (15) the second sintering is performed under oxygen flow and uses stepwise temperature rising, and the temperature rising rate is 2-10℃ / min; (16) the highest temperature of the third sintering is 400-700℃, and the time of the third sintering is 2-8h; (17) the third sintering is performed under oxygen flow and uses stepwise temperature rising, and the temperature rising rate is 2-10℃ / min; (18) the first pulverization uses an air flow pulverizer; (19) the second pulverization includes sequentially using a rotary wheel grinder and a mechanical pulverizer to pulverize the solid obtained after the first sintering; (20) the third pulverization uses a mechanical pulverizer.

7. Use of the nickel-cobalt-lithium manganate-based positive electrode material prepared according to the method of any one of claims 1-4 or 5-6 in a positive electrode material.

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