Lithium-rich manganese-based ternary precursor as well as preparation method and application thereof

Abstract

The invention provides a preparation method of a lithium-rich manganese-based ternary precursor. The preparation method comprises the following steps: respectively preparing a nickel-cobalt-manganese mixed salt solution, a sodium carbonate solution and an ammonia water solution; adding water and ammonium bicarbonate into the preparation device, controlling the pH value of the solution in the reaction kettle to be 7-11, then adding a reducing substance, introducing protective gas into the preparation device, and keeping the solution in the preparation device to circulate; the prepared three solutions are introduced into a reaction kettle for stirring reaction, the reaction temperature is 45-65 DEG C, the pH value of the solutions is 7.0-9.0, and shielding gas is continuously introduced in the reaction; starting a cleaning function of the concentration machine after feeding for 1-6 hours, and continuously increasing the alkalinity and temperature of the solution and reducing the stirring rotating speed; and aging, alkali washing, water washing and drying the reaction product to obtain the lithium-rich manganese-based ternary precursor. The lithium-rich manganese-based ternary precursor prepared by the preparation method of the lithium-rich manganese-based ternary precursor provided by the invention can be used for preparing a lithium-rich manganese-based positive electrode material with high capacity and long cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and in particular to a lithium-rich manganese-based ternary precursor and a preparation method and application thereof. Background Art

[0002] With the continuous upgrading of market demand for power batteries, the development of high energy density, high cycle performance and high safety lithium-ion battery positive electrode materials and precursors is imminent. Although the current medium-nickel high-voltage and high-nickel ultra-high-nickel ternary materials have a high capacity of more than 200mAh / g, it is difficult to further increase their capacity. Compared with traditional commercial positive electrodes such as lithium iron phosphate and ternary materials, lithium-rich manganese-based positive electrode materials can provide a high capacity of more than 250mAh / g due to the joint participation of anions and cations in the redox reaction, and will become the direction of future research and development. Precursors are key basic materials for the preparation of positive electrode materials. More than half of the performance of positive electrode materials depends on the performance of the corresponding precursors. Therefore, the development of high-performance precursors is the key to the preparation of high-capacity and long-cycle lithium-rich manganese positive electrode materials.

[0003] At present, the main disadvantages of lithium-rich manganese-based materials are low first coulombic efficiency and severe capacity attenuation. The first coulombic efficiency of most lithium-rich manganese-based materials is between 70% and 80%. The low first coulombic efficiency will also have an adverse effect on the material's cycle performance.

[0004] Therefore, there is an urgent need for a lithium-rich manganese-based ternary precursor and a preparation method thereof that can be used to prepare high-capacity and long-cycle lithium-rich manganese-based positive electrode materials, so as to overcome the problems of low initial efficiency and severe capacity attenuation of current lithium-rich manganese-based positive electrode materials. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a lithium-rich manganese-based ternary precursor and a preparation method thereof for preparing high-capacity and long-cycle lithium-rich manganese-based positive electrode materials, so as to overcome the problems of low initial efficiency and severe capacity attenuation of current lithium-rich manganese-based positive electrode materials.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a lithium-rich manganese-based ternary precursor, comprising the following steps:

[0007] Prepare a nickel-cobalt-manganese mixed salt solution with a concentration of 0.5-2.5 mol / L using NiSO4, CoSO4 and MnSO4, prepare a sodium carbonate solution with a concentration of 1-5 mol / L, and prepare an ammonia solution with a concentration of 2-13 mol / L;

[0008] Add water to the preparation device consisting of a reactor, an intermediate tank and a concentrator, and add 100-500g of ammonium bicarbonate, control the pH of the solution in the reactor to 7-11, then add a reducing substance, and then introduce a protective gas into the preparation device, and keep the solution circulating in the preparation device;

[0009] The nickel-cobalt-manganese mixed salt solution, sodium carbonate solution and ammonia solution are introduced into a reaction kettle for stirring and reaction, the reaction temperature is 45-65° C., the solution pH is 7.0-9.0, and protective gas is continuously introduced during the reaction;

[0010] After 1-6 hours of feeding, the concentrator is turned on to clear the solution, the alkalinity of the solution is increased by 0-0.5 g / L per hour, the temperature of the solution is increased by 0-0.5 ° C per hour, and the stirring speed is reduced by 0-10 r per hour;

[0011] The reaction product is aged, drained, washed with alkali, washed with water and dried to obtain a lithium-rich manganese-based ternary precursor.

[0012] Furthermore, the reactor of the preparation device is respectively connected to the intermediate tank and the concentrator pipeline, the concentrator is connected to the intermediate tank pipeline, a diaphragm pump is arranged on the connecting pipeline between the intermediate tank and the concentrator, a clear liquid outlet is arranged on the concentrator, and three liquid inlet pipes A1, A2 and A3 are arranged on the reactor.

[0013] Furthermore, water is added to the preparation device until the liquid level is 80% of the volume of the reactor.

[0014] Furthermore, the reducing substance is hydrazine hydrate and / or ascorbic acid.

[0015] Furthermore, the nickel-cobalt-manganese mixed salt solution, sodium carbonate solution and ammonia solution are respectively introduced into the reactor through liquid inlet pipes A1, A2 and A3, the feed flow rate of the nickel-cobalt-manganese mixed salt solution is controlled at 0-10 L / h, and the feed flow rate of the ammonia solution is controlled at 0-5 L / h.

[0016] Furthermore, the stirring speed of the stirring reaction is controlled to be 400-1000r / min.

[0017] The lithium-rich manganese-based ternary precursor prepared by the present invention has a chemical formula of Ni X Co Y Mn Z CO3, where X+Y+Z=1, 0<X<0.3, 0<Y<0.2, 0.5<Z<1.0.

[0018] The present invention also provides a lithium-rich manganese-based positive electrode material, which is prepared from the lithium-rich manganese-based ternary precursor prepared by the method of the present invention.

[0019] Furthermore, the preparation method of the lithium-rich manganese-based positive electrode material is as follows:

[0020] The lithium-rich manganese-based ternary precursor is mixed with lithium carbonate or lithium hydroxide in a ratio of 1:2-1:6 to obtain a mixture;

[0021] The mixture is sintered for 2-15 hours at 500-1000° C. and an oxygen concentration of 80%-100% to obtain a lithium-rich manganese-based positive electrode material.

[0022] Furthermore, the first coulombic efficiency of the lithium-rich manganese-based material is above 80%, and at 2.0-4.8V, with a charge and discharge regime of 0.1C / 0.1C, the first discharge of the lithium-rich manganese-based material is above 280mAh / g.

[0023] The invention provides a preparation method of a lithium-rich manganese-based ternary precursor. The method adopts an intermittent process route, wherein an appropriate amount of water and a certain amount of weakly alkaline ammonium bicarbonate are added to a preparation device to control the pH value of the solution, and then a reducing substance is added. Under a protective atmosphere and at a suitable temperature, a nickel-cobalt-manganese mixed salt solution, a sodium carbonate alkaline solution and an ammonia solution of a predetermined concentration are continuously introduced simultaneously, and the reaction mass ratio of the nickel-cobalt-manganese mixed salt solution and the ammonia solution is controlled by controlling the introduction flow rate of the nickel-cobalt-manganese mixed salt solution and the ammonia solution, so that the mixed solution continuously reacts in a circulating weakly alkaline ammonium bicarbonate solution, and the three solutions are introduced for 1-6 hours for clearing, and then the alkalinity and temperature are increased and the rotation speed is reduced until the synthesis reaction is stopped. After the particle size reaches the standard, the product is subjected to aging and drying and other treatments to obtain a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution and no cracks on the surface of secondary particles.

[0024] The lithium-rich manganese-based ternary precursor prepared by the present invention is used to prepare a lithium-rich manganese-based positive electrode material. The prepared lithium-rich manganese-based material has an initial coulombic efficiency of more than 80%. Under the condition of 2.0-4.8V, with a 0.1C / 0.1C charge and discharge system, its initial discharge is more than 280mAh / g, which completely overcomes the problems of low initial efficiency and severe capacity attenuation of current lithium-rich manganese-based positive electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of a method for preparing a lithium-rich manganese-based ternary precursor provided in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the structure of a preparation device used in a method for preparing a lithium-rich manganese-based ternary precursor provided in an embodiment of the present invention;

[0027] Figure 3 An electron microscope image of a lithium-rich manganese-based ternary precursor prepared by the method for preparing a lithium-rich manganese-based ternary precursor provided in Example 1 of the present invention;

[0028] Figure 4 This is an electron microscope image of a lithium-rich manganese-based positive electrode material prepared using the lithium-rich manganese-based ternary precursor prepared in Example 1 of the present invention;

[0029] Figure 5An electron microscope image of a lithium-rich manganese-based ternary precursor prepared by the method for preparing a lithium-rich manganese-based ternary precursor provided in Example 2 of the present invention;

[0030] Figure 6 This is an electron microscope image of a lithium-rich manganese-based positive electrode material prepared using the lithium-rich manganese-based ternary precursor prepared in Example 2 of the present invention;

[0031] Figure 7 An electron microscope image of a lithium-rich manganese-based ternary precursor prepared by the method for preparing a lithium-rich manganese-based ternary precursor provided in Example 3 of the present invention;

[0032] Figure 8 This is an electron microscope image of a lithium-rich manganese-based positive electrode material prepared using the lithium-rich manganese-based ternary precursor prepared in Example 3 of the present invention;

[0033] Fig. 9 An electron microscope image of a lithium-rich manganese-based ternary precursor prepared by the lithium-rich manganese-based ternary precursor preparation method provided in the comparative example;

[0034] Fig.10 This is an electron microscope image of a lithium-rich manganese-based positive electrode material made from a lithium-rich manganese-based ternary precursor prepared in the comparative example.

[0035] In the figure: 1-reactor, 2-intermediate tank, 3-concentrator, 4-diaphragm pump. DETAILED DESCRIPTION

[0036] See also Figure 1 , a method for preparing a lithium-rich manganese-based ternary precursor provided by an embodiment of the present invention comprises the following steps:

[0037] Step 1) Prepare a nickel-cobalt-manganese mixed salt solution with a concentration of 0.5-2.5 mol / L using NiSO4, CoSO4 and MnSO4, prepare a sodium carbonate solution with a concentration of 1-5 mol / L, and prepare an ammonia solution with a concentration of 2-13 mol / L.

[0038] Among them, NiSO4, CoSO4 and MnSO4 are prepared into a nickel-cobalt-manganese mixed salt solution in a ratio of X:Y:Z.

[0039] Among them, X+Y+Z=1, 0<X<0.3, 0<Y<0.2, 0.5<Z<1.0.

[0040] Step 2) Pure water is added to the preparation device consisting of the reactor 1, the intermediate tank 2 and the concentrator 3, and 100-500 g of ammonium bicarbonate is added, the pH of the solution in the reactor is controlled at 7-11, and then a reducing substance is added, and then a protective gas is introduced into the preparation device to replace the air in the device, and then a diaphragm pump is operated to promote continuous circulation of the solution in the preparation device.

[0041] Among them, see Figure 2 The reactor 1 of the preparation device is connected with the intermediate tank 2 and the concentrator 3 through pipelines, respectively. The concentrator 3 is also connected with the intermediate tank 2 through pipelines, and a diaphragm pump 4 is arranged on the connecting pipeline between the intermediate tank 2 and the concentrator 3. By running the diaphragm pump 4, the solution in the preparation device can be continuously circulated in the reactor 1, the intermediate tank 2 and the concentrator 3. At the same time, a clear liquid outlet is arranged on the concentrator 3. When the clearing function of the concentrator 3 is turned on, the excess solution in the preparation device can be discharged from the clear liquid outlet, thereby ensuring the stability of the liquid level in the reactor 1. In addition, three liquid inlet pipes A1, A2 and A3 are arranged on the reactor 1.

[0042] When adding pure water to the preparation device composed of the reactor 1, the intermediate tank 2 and the concentrator 3, in order to ensure the effective liquid volume in the reactor body of the reactor 1 and to promote the reaction in the reactor 1 to be repeated, the pure water in the reactor 1 is added to the liquid level to 80% of the volume of the reactor.

[0043] Wherein, the reducing substance is hydrazine hydrate and / or ascorbic acid.

[0044] Step 3) The nickel-cobalt-manganese mixed salt solution, the sodium carbonate solution and the ammonia solution are continuously introduced into the reactor 1 through the three liquid inlet pipes A1, A2 and A3 on the reactor 1, and are continuously stirred by the stirrer in the reactor to promote the biochemical reaction between the nickel-cobalt-manganese mixed salt and the ammonia solution in the solution. The stirring speed of the stirrer is controlled at 400-1000 r / min.

[0045] The reaction temperature is controlled at 45-65°C, and the pH of the reaction solution is controlled at 7.0-9.0 by sodium carbonate solution. In addition, in order to prevent the metal ions in the solution from undergoing oxidation reaction with oxygen during the reaction, protective gas is continuously introduced during the reaction to prevent air from entering the reaction solution.

[0046] In order to ensure that a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution and no cracks on the surface of secondary particles can be obtained in the end, so as to ensure that a high-capacity and long-cycle lithium-rich manganese-based positive electrode material can be prepared, not only the reaction temperature is controlled at 45-65°C, the pH of the reaction solution is controlled at 7.0-9.0 by sodium carbonate solution, and protective gas is continuously introduced into the reaction solution, but also the solution concentration and feed flow rate of the nickel-cobalt-manganese mixed salt solution and the ammonia solution are controlled so that the nickel-cobalt-manganese mixed salt and the ammonia water in the solution are mixed and reacted in a certain mass ratio.

[0047] As a specific embodiment of the present invention, the mixed concentration of the nickel-cobalt-manganese mixed salt solution prepared by NiSO4, CoSO4 and MnSO4 is controlled to be 0.5-2.5 mol / L, the concentration of the sodium carbonate solution is controlled to be 1-5 mol / L, the concentration of the ammonia solution is controlled to be 2-13 mol / L, and the feed flow rate of the nickel-cobalt-manganese mixed salt solution is controlled to be 0-10 L / h, and the feed flow rate of the ammonia solution is controlled to be 0-5 L / h.

[0048] Step 4) After continuously introducing the nickel-cobalt-manganese mixed salt solution, the sodium carbonate solution and the ammonia solution into the reactor 1 through the three liquid inlet pipes A1, A2 and A3 on the reactor 1 for 1-6 hours, in order to ensure the stability of the liquid level in the reactor 1, the clearing function of the concentrator 3 is turned on, and in the subsequent reaction process, the alkalinity of the reaction solution is increased by 0-0.5 g / L per hour, the temperature of the reaction solution is increased by 0-0.5° C. per hour, and the stirring speed is reduced by 0-10r per hour until the synthesis reaction is stopped.

[0049] Step 5) When the particle size of the reaction product reaches the standard value, the reaction product is subjected to aging, clearing liquid, alkali washing, water washing, drying and other process processes to obtain a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution and no cracks on the surface of secondary particles.

[0050] The lithium-rich manganese-based ternary precursor prepared by the present invention has a chemical formula of Ni X Co Y Mn Z CO3, wherein X+Y+Z=1, 0<X<0.3, 0<Y<0.2, 0.5<Z<1.0. The obtained lithium-rich manganese-based ternary precursor has the characteristics of good sphericity, narrow particle size distribution, and no cracks on the surface of secondary particles. The obtained lithium-rich manganese-based ternary precursor can be used for the preparation of lithium-rich manganese-based positive electrode materials.

[0051] The present invention provides a lithium-rich manganese-based positive electrode material, which is prepared using the lithium-rich manganese-based ternary precursor prepared by the above method of the present invention. The specific preparation method includes the following steps:

[0052] First, the prepared lithium-rich manganese-based ternary precursor is mixed with lithium carbonate or lithium hydroxide in a ratio of 1:2-1:6 to obtain a mixture.

[0053] The mixture is then sintered for 2-15 hours at 500-1000° C. and an oxygen concentration of 80%-100% to obtain a lithium-rich manganese-based positive electrode material.

[0054] Among them, the first coulombic efficiency of the prepared lithium-rich manganese-based material is above 80%, and at 2.0-4.8V, with a charge and discharge system of 0.1C / 0.1C, the first discharge of the lithium-rich manganese-based material is above 280mAh / g.

[0055] The preparation method of the lithium-rich manganese-based ternary precursor provided by the present invention adopts an intermittent process route, adds an appropriate amount of water and a certain amount of weak alkaline ammonium bicarbonate into a preparation device to control the pH value of the solution, then adds a reducing substance, and continuously introduces a nickel-cobalt-manganese mixed salt solution, a sodium carbonate alkaline solution and an ammonia solution of a predetermined concentration under a protective atmosphere and a suitable temperature condition, and controls the reaction mass ratio of the nickel-cobalt-manganese mixed salt solution and the ammonia solution by controlling the introduction flow rate of the nickel-cobalt-manganese mixed salt solution and the ammonia solution, so that the mixed solution continuously reacts in the circulating weak alkaline ammonium bicarbonate solution, and clears after the three solutions are introduced for 1-6 hours, and then increases the alkalinity and temperature and reduces the rotation speed until the synthesis reaction is stopped. After the particle size reaches the standard, the product is subjected to aging and drying and other treatments to obtain a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution and no cracks on the surface of secondary particles.

[0056] In addition, the lithium-rich manganese-based ternary precursor prepared by the present invention is used to prepare a lithium-rich manganese-based positive electrode material. The prepared lithium-rich manganese-based material has an initial coulombic efficiency of more than 80%. Under the condition of 2.0-4.8V, with a 0.1C / 0.1C charge and discharge system, its initial discharge is more than 280mAh / g, which completely overcomes the problems of low initial efficiency and severe capacity attenuation of current lithium-rich manganese-based positive electrode materials.

[0057] The following is a detailed description of a lithium-rich manganese-based ternary precursor provided by the present invention and its preparation method and application through examples and comparative examples.

[0058] Example 1

[0059] Prepare a first solution, wherein the molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate is 3:1:6 respectively, the total concentration of the salt in the first solution is 2.0 mol / L, prepare a 2.0 mol / L sodium carbonate solution as the second solution, and prepare a 4 mol / L ammonia solution as the third solution. Inject pure water into the reactor, the intermediate tank and the concentrator respectively to 80% of the volume of the reactor, add a total of 400 g of ammonium bicarbonate to the reactor, the intermediate tank and the concentrator, add the reducing substance hydrazine hydrate, ensure that the pH value inside the reactor is 8.0, and introduce protective gas into the reactor, the intermediate tank and the concentrator to replace the air, and the solution is circulated by a diaphragm pump. The first solution, the second solution and the third solution are introduced into the reactor through the A1, A2 and A3 inlet pipes at a suitable flow rate for reaction. The flow rate of the first solution was controlled at 3.6L / h, the flow rate of the third solution was controlled at 0.9L / h, the temperature in the reactor was maintained at 55°C, the pH was adjusted to 8.0 by adding 2.0mol / L of sodium carbonate, the stirring speed was controlled at 700r / min, and the protective gas was continuously introduced during the reaction to prevent metal ion oxidation. The clearing function was turned on after feeding for 3h. As the particle size increases, the alkalinity is increased by 0.2g / L per hour, the temperature is increased by 0-0.1°C per hour, and the rotation speed is reduced by 5r per hour. After the particle size reaches the standard value, the output product is aged, drained, alkali washed, washed with water, and dried to obtain a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution, and no cracks on the surface of the secondary particles. The product molecular formula is Ni X Co Y Mn Z CO3.

[0060] Using the above method, the particle size data of the product obtained in the embodiment of the present invention are D10 of 6.62 μm, D50 of 10.41 μm, D90 of 14.89 μm, and D100 of 17.47 μm. The electron microscope image of the lithium-rich manganese-based ternary precursor obtained in the embodiment of the present invention is as follows: Figure 3 shown.

[0061] The lithium-rich manganese-based ternary precursor prepared in the embodiment of the present invention was mixed with lithium carbonate in a ratio of 1:3, and sintered at 800°C, an oxygen concentration of 85%, and a time of 12 hours to prepare a lithium-rich manganese-based positive electrode material. Under the conditions of 2.0-4.8V, the charge and discharge system was 0.1C / 0.1C, and the first discharge was 282.58mAh / g, and the first coulomb efficiency was 88.40%. The electrical performance statistics of the lithium-rich manganese-based positive electrode material prepared in the embodiment of the present invention under the 0.1C / 0.1C charge and discharge system are shown in Table 1. The electron microscope image of the lithium-rich manganese-based positive electrode material prepared in the embodiment of the present invention is shown in Table 1. Figure 4 shown.

[0062] Table 1

[0063]

[0064] Example 2

[0065] Prepare a first solution, wherein the molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate is 3:1:6 respectively, the total concentration of the salt in the first solution is 2.0 mol / L, prepare a 2.0 mol / L sodium carbonate solution as the second solution, and prepare a 4 mol / L ammonia solution as the third solution. Inject pure water into the reactor, the intermediate tank and the concentrator respectively to 80% of the volume of the reactor, add a total of 450 g of ammonium bicarbonate to the reactor, the intermediate tank and the concentrator, add the reducing substance hydrazine hydrate, ensure that the pH value inside the reactor is 8.2, and introduce protective gas into the reactor, the intermediate tank and the concentrator to replace the air, and the solution is circulated by a diaphragm pump. The first solution, the second solution and the third solution are introduced into the reactor through the A1, A2 and A3 inlet pipes at a suitable flow rate for reaction. The flow rate of the first solution was controlled at 3.6L / h, the flow rate of the third solution was controlled at 0.45L / h, the temperature in the reactor was maintained at 55°C, the pH was adjusted to 8.2 by adding 2.0mol / L of sodium carbonate, the stirring speed was controlled at 700r / min, and the protective gas was continuously introduced during the reaction to prevent metal ion oxidation. The clearing function was turned on after feeding for 3h. As the particle size increases, the alkalinity is increased by 0.2g / L per hour, the temperature is increased by 0-0.1°C per hour, and the rotation speed is reduced by 5r per hour. After the particle size reaches the standard value, the output product is aged, drained, washed with alkali, washed with water, and dried to obtain a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution, and no cracks on the surface of the secondary particles. The product molecular formula is Ni X Co Y Mn Z CO3.

[0066] Using the above method, the particle size data of the product obtained in the embodiment of the present invention are D10 of 6.35 μm, D50 of 10.23 μm, D90 of 14.41 μm, and D100 of 17.07 μm. The electron microscope image of the lithium-rich manganese-based ternary precursor obtained in the embodiment of the present invention is as follows: Figure 5 shown.

[0067] The lithium-rich manganese-based ternary precursor prepared in the embodiment of the present invention was mixed with lithium carbonate in a ratio of 1:3, and sintered at 800°C, an oxygen concentration of 85%, and a time of 12 hours to prepare a lithium-rich manganese-based positive electrode material. Under the conditions of 2.0-4.8V, the charge and discharge system was 0.1C / 0.1C, and the first discharge was 280.58mAh / g, and the first coulomb efficiency was 87.91%. The electrical performance statistics of the lithium-rich manganese-based positive electrode material prepared in the embodiment of the present invention under the 0.1C / 0.1C charge and discharge system are shown in Table 1. The electron microscope image of the lithium-rich manganese-based positive electrode material prepared in the embodiment of the present invention is shown in Table 1. Figure 6 shown.

[0068] Example 3

[0069] Prepare a first solution, wherein the molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate is 3:1:6 respectively, the total concentration of the salt in the first solution is 2.0 mol / L, prepare a 2.0 mol / L sodium carbonate solution as the second solution, and prepare a 4 mol / L ammonia solution as the third solution. Inject pure water into the reactor, the intermediate tank and the concentrator respectively to 80% of the volume of the reactor, add a total of 330 g of ammonium bicarbonate to the reactor, the intermediate tank and the concentrator, add the reducing substance hydrazine hydrate, ensure that the pH value inside the reactor is 7.8, pass the reactor, the intermediate tank and the concentrator into protective gas to replace the air, and circulate the solution through a diaphragm pump. The first solution, the second solution and the third solution are passed into the reactor through the A1, A2 and A3 inlet pipes at a suitable flow rate for reaction. The flow rate of the first solution was controlled at 3.6L / h, the flow rate of the third solution was controlled at 1.8L / h, the temperature in the reactor was maintained at 55°C, the pH was adjusted to 7.8 by adding 2.0mol / L of sodium carbonate, the stirring speed was controlled at 700r / min, and the protective gas was continuously introduced during the reaction to prevent metal ion oxidation. The clearing function was turned on after feeding for 3h. As the particle size increases, the alkalinity is increased by 0.2g / L per hour, the temperature is increased by 0-0.1°C per hour, and the rotation speed is reduced by 5r per hour. After the particle size reaches the standard value, the output product is aged, drained, washed with alkali, washed with water, and dried to obtain a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution, and no cracks on the surface of the secondary particles. The product molecular formula is Ni X Co Y Mn Z CO3.

[0070] Using the above method, the particle size data of the product obtained in the embodiment of the present invention are D10 of 6.89 μm, D50 of 10.41 μm, D90 of 14.67 μm, and D100 of 17.88 μm. The electron microscope image of the lithium-rich manganese-based ternary precursor obtained in the embodiment of the present invention is as follows: Figure 7 shown.

[0071] The lithium-rich manganese-based ternary precursor prepared in the embodiment of the present invention was mixed with lithium carbonate in a ratio of 1:3, and sintered at 800°C, an oxygen concentration of 85%, and a time of 12 hours to prepare a lithium-rich manganese-based positive electrode material. Under the conditions of 2.0-4.8V, the charge and discharge system was 0.1C / 0.1C, and the first discharge was 284.07mAh / g, and the first coulomb efficiency was 86.63%. The electrical performance statistics of the lithium-rich manganese-based positive electrode material prepared in the embodiment of the present invention under the 0.1C / 0.1C charge and discharge system are shown in Table 1. The electron microscope image of the lithium-rich manganese-based positive electrode material prepared in the embodiment of the present invention is shown in Table 1. Figure 8 shown.

[0072] Comparative Example

[0073] Prepare a first solution, wherein the molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate is 3:1:6 respectively, the total concentration of the salt in the first solution is 2.0 mol / L, prepare a 2.0 mol / L sodium carbonate solution as the second solution, and prepare a 4 mol / L ammonia solution as the third solution. Inject pure water into the reactor, the intermediate tank and the concentrator respectively to 80% of the volume of the reactor, add a total of 650 g of ammonium bicarbonate to the reactor, the intermediate tank and the concentrator, add the reducing substance hydrazine hydrate, ensure that the pH value inside the reactor is 9.5, and introduce protective gas into the reactor, the intermediate tank and the concentrator to replace the air, and the solution is circulated by a diaphragm pump. The first solution, the second solution and the third solution are introduced into the reactor through the A1, A2 and A3 inlet pipes at a suitable flow rate for reaction. The flow rate of the first solution was controlled at 3.6L / h, the flow rate of the third solution was controlled at 0.9 / h, the temperature in the reactor was maintained at 55°C, the pH was adjusted to 9.5 by adding 2.0mol / L of sodium carbonate, the stirring speed was controlled at 700r / min, and the protective gas was continuously introduced during the reaction to prevent metal ion oxidation. The clearing function was turned on after feeding for 3h. As the particle size increases, the alkalinity is increased by 0.2g / L per hour, the temperature is increased by 0-0.1°C per hour, and the rotation speed is reduced by 5r per hour. After the particle size reaches the standard value, the output product is aged, drained, alkali washed, washed with water, and dried to obtain a lithium-rich manganese-based ternary precursor with good sphericity, narrow particle size distribution, and no cracks on the surface of the secondary particles. The product molecular formula is Ni X Co Y Mn Z CO3.

[0074] Using the above method, the particle size data of the product obtained in this comparative example are D10 of 6.01 μm, D50 of 10.66 μm, D90 of 14.87 μm, and D100 of 17.31 μm. The electron microscope image of the lithium-rich manganese-based ternary precursor obtained in the embodiment of the present invention is as follows: Fig. 9 shown.

[0075] The lithium-rich manganese-based ternary precursor prepared in this comparative example was mixed with lithium carbonate in a ratio of 1:3, and sintered at 800°C, an oxygen concentration of 85%, and a time of 12h to prepare a lithium-rich manganese-based positive electrode material. Under the conditions of 2.0-4.8V, the charge and discharge system was 0.1C / 0.1C, and the first discharge was 226.43mAh / g, and the first coulomb efficiency was 75%. The electrical performance statistics of the lithium-rich manganese-based positive electrode material prepared in this comparative example under the 0.1C / 0.1C charge and discharge system are shown in Table 1. The electron microscope image of the lithium-rich manganese-based positive electrode material prepared in this comparative example is shown in Table 1. Fig.10 shown.

[0076] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a lithium-rich manganese-based ternary precursor, characterized in that: The steps include: Prepare a nickel-cobalt-manganese mixed salt solution with a concentration of 0.5-2.5 mol / L using NiSO4, CoSO4 and MnSO4, prepare a sodium carbonate solution with a concentration of 1-5 mol / L, and prepare an ammonia solution with a concentration of 2-13 mol / L; Add water to the preparation device consisting of a reactor, an intermediate tank and a concentrator, and add 100-500g of ammonium bicarbonate, control the pH of the solution in the reactor to 7-11, then add a reducing substance, and then introduce a protective gas into the preparation device, and keep the solution circulating in the preparation device; The nickel-cobalt-manganese mixed salt solution, sodium carbonate solution and ammonia solution are introduced into a reaction kettle for stirring and reaction, the reaction temperature is 45-65° C., the solution pH is 7.0-9.0, and protective gas is continuously introduced during the reaction; After 1-6 hours of feeding, the concentrator is turned on to clear the solution, the alkalinity of the solution is increased by 0-0.5 g / L per hour, the temperature of the solution is increased by 0-0.5 ° C per hour, and the stirring speed is reduced by 0-10 r per hour; The reaction product is aged, drained, washed with alkali, washed with water and dried to obtain a lithium-rich manganese-based ternary precursor.

2. The method for preparing a lithium-rich manganese-based ternary precursor according to claim 1, characterized in that: The reactor of the preparation device is respectively connected to the intermediate tank and the concentrator pipeline, the concentrator is connected to the intermediate tank pipeline, a diaphragm pump is arranged on the connecting pipeline between the intermediate tank and the concentrator, a clear liquid outlet is arranged on the concentrator, and three liquid inlet pipes A1, A2 and A3 are arranged on the reactor.

3. The method for preparing a lithium-rich manganese-based ternary precursor according to claim 2, characterized in that: Water is added to the preparation device until the liquid level is 80% of the volume of the reactor.

4. The method for preparing a lithium-rich manganese ternary precursor according to claim 1, characterized in that: The reducing substance is hydrazine hydrate and / or ascorbic acid.

5. The method for preparing a lithium-rich manganese-based ternary precursor according to claim 2, characterized in that: The nickel-cobalt-manganese mixed salt solution, sodium carbonate solution and ammonia solution are respectively introduced into the reactor through liquid inlet pipes A1, A2 and A3. The feed flow rate of the nickel-cobalt-manganese mixed salt solution is controlled at 0-10 L / h, and the feed flow rate of the ammonia solution is controlled at 0-5 L / h.

6. The method for preparing a lithium-rich manganese-based ternary precursor according to claim 1, characterized in that: The stirring speed of the stirring reaction is controlled to be 400-1000r / min.

7. A lithium-rich manganese-based ternary precursor, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6, the chemical formula of the lithium-rich manganese-based precursor is Ni X Co Y Mn Z CO3, where X+Y+Z=1, 0<X<0.3, 0<Y<0.2, 0.5<Z<1.

0.

8. A lithium-rich manganese-based positive electrode material, characterized in that: It is prepared from the lithium-rich manganese-based ternary precursor according to claim 7.

9. The lithium-rich manganese-based positive electrode material according to claim 8, characterized in that: The preparation method of the lithium-rich manganese-based positive electrode material is as follows: The lithium-rich manganese-based ternary precursor is mixed with lithium carbonate or lithium hydroxide in a ratio of 1:2-1:6 to obtain a mixture; The mixture is sintered for 2-15 hours at 500-1000° C. and an oxygen concentration of 80%-100% to obtain a lithium-rich manganese-based positive electrode material.

10. The lithium-rich manganese-based positive electrode material according to claim 9, characterized in that: The first coulombic efficiency of the lithium-rich manganese-based material is above 80%, and at 2.0-4.8V, with a charge and discharge regime of 0.1C / 0.1C, the first discharge of the lithium-rich manganese-based material is above 280mAh / g.

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