A microreactor and a preparation method and application thereof for a precursor of a lithium battery cathode material

Abstract

The present invention provides a microreactor and a preparation method and application thereof for a precursor of a lithium battery cathode material. The microreactor includes a reaction kettle cylinder body; a draft tube arranged inside the reaction kettle cylinder body; a stirring shaft extending into the draft tube; a stirring device arranged on the stirring shaft; and a plurality of openings arranged on the cylinder wall of the draft tube. With the assistance of the draft tube with a plurality of openings, the microreactor provided by the present invention enables multiple internal and external circulations to be established inside the reactor. Under the synergistic action in multiple aspects, the material size can be reduced, the reaction can be made more sufficient and uniform, so as to achieve controllable particle size. The lithium battery cathode material obtained by mixing lithium and sintering and modifying the precursor of the lithium battery cathode material prepared by using the above microreactor has high compaction, high rate and good cycle stability, and is an important choice for high-energy-density and long-life lithium ion batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of cathode materials, and particularly relates to a microreactor and a preparation method and application thereof for a precursor of a lithium battery cathode material. Background Art

[0002] As a secondary battery, lithium-ion batteries have been commercially applied in small power battery fields such as 3C electronic products, mobile power supplies, power tools, and electric bicycles. The cathode materials used mainly include lithium iron phosphate, lithium manganate, lithium cobaltate, and ternary materials, etc., and their actual specific capacities are all lower than 200 mA·h / g. With the change of the global energy pattern and the supply limitation of nickel, cobalt, and manganese resources, lithium-rich manganese-based cathode materials with high specific capacity (>250 mA·h / g) and low cost have attracted extensive attention of researchers and are expected to be commercially used as the cathode materials for the next generation of power batteries, such as hybrid electric vehicles (HEV) or pure electric vehicles (EV).

[0003] Currently, the methods for synthesizing lithium-rich manganese-based ternary materials mainly include high-temperature solid-phase method, sol-gel method, hydrothermal synthesis method, and co-precipitation method, etc. Among them, the co-precipitation method is the most widely used in the liquid-phase chemical synthesis of powder materials. The effective components in the product can achieve uniform mixing at the atomic and molecular levels, and the equipment is simple and the operation is easy. However, restricted by the strict production conditions of this process, there are deficiencies such as too fast and too large growth of early crystal particles, wide particle size distribution of the finally prepared precursor particles, and low tap density of the particles, thus limiting the performance improvement space of the subsequent finished cathode materials. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a microreactor and a preparation method and application thereof for a precursor of a lithium battery cathode material. The precursor particles prepared by this microreactor have controllable and uniform particle size, regular morphology, and high tap density.

[0005] The present invention provides a microreactor for synthesizing a precursor of a lithium battery cathode material, including a reaction kettle cylinder body;

[0006] A draft tube arranged in the reaction kettle cylinder body;

[0007] A stirring shaft extending into the draft tube; a stirring device is arranged on the stirring shaft;

[0008] A plurality of openings are arranged on the barrel wall of the draft tube.

[0009] Preferably, the plurality of openings are mirror-symmetrically distributed around the axis of the stirring shaft.

[0010] Preferably, the plurality of stirring devices are installed on the stirring shaft;

[0011] A plurality of the stirring devices are arranged in sequence along the axis of the stirring shaft.

[0012] Preferably, at least one opening is provided between two adjacent stirring devices in the height direction of the reactor cylinder.

[0013] Preferably, the following relationships are satisfied among the diameter D of the reactor cylinder, the gap L between the draft tube and the side wall of the reactor, the height gap H between adjacent openings, the inner diameter d of the draft tube, and the height h of the opening:

[0014] d = (1 / 2 - 9 / 10)D; L = (D - d) / 2; H = h = (1 / 10 - 1 / 2)d.

[0015] Preferably, the number of layers of the stirring devices is 1 - 16 layers.

[0016] Preferably, the ratio of the number of layers of the openings to the number of layers of the stirring devices is 1:1.

[0017] The present invention provides a method for preparing a precursor of a lithium battery cathode material, comprising the following steps:

[0018] Mix a nickel-containing compound, a cobalt-containing compound, a manganese-containing compound, and water to obtain a mixed salt solution;

[0019] Add the mixed salt solution, a precipitant, a complexing agent, and an auxiliary agent into the microreactor described in the above technical solution, and carry out a coprecipitation reaction under stirring conditions to obtain a nickel cobalt manganese precursor; during the coprecipitation reaction, control the solid content and stirring speed in the reactor system to form a vortex of the materials in the reactor cylinder;

[0020] Age and wash the nickel cobalt manganese precursor to obtain a precursor for a lithium battery cathode material.

[0021] Preferably, the pH value of the coprecipitation reaction is 7 - 12; the time of the coprecipitation reaction is 10 - 120 h;

[0022] The aging time is 10 - 48 h.

[0023] The present invention provides a lithium ion battery cathode material, which is prepared by sintering a precursor for a lithium battery cathode material and a lithium salt prepared by the preparation method described in the above technical solution.

[0024] The present invention provides a microreactor for synthesizing a precursor of a lithium battery cathode material, comprising a reaction kettle cylinder body; a draft tube arranged inside the reaction kettle cylinder body; a stirring shaft extending into the draft tube; a stirring device arranged on the stirring shaft; and a plurality of openings arranged on the cylinder wall of the draft tube. With the assistance of the draft tube with a plurality of openings, the microreactor provided by the present invention enables the establishment of multiple internal and external circulations inside the reactor. Under the synergistic action of multiple aspects, the material size can be reduced, and the reaction can be made more sufficient and uniform, so as to achieve controllable particle size. The lithium battery cathode material obtained by mixing lithium and sintering and modifying the precursor of the lithium battery cathode material prepared by using the above microreactor has high tap density, high rate and good cycle stability, which is an important choice for high-energy-density and long-life lithium ion batteries. The experimental results show that the tap density of the precursor is 2.18-2.28 g / ml; D 50 is 6-15 μm; the first discharge capacity of the battery reaches 178-301 mA h / g, and the capacity retention rate is 87.9-92.5% after 500 cycles of charge and discharge at 0.5C. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the grid reactor;

[0026] Figure 2 is a schematic diagram of the openings on the microreactor;

[0027] Figure 3 is a schematic diagram of the internal fluid flow direction of the microreactor;

[0028] Figure 4 is the Ni prepared in Example 1 of the grid reactor 0.25 Co 0.15 Mn 0.6 Mg 0.05 SEM image of the CO3 precursor particles;

[0029] Figure 5 is the Ni prepared in Example 1 of the present invention 0.25 Co 0.15 Mn 0.6 Mg 0.05 Particle size distribution diagram of the CO3 precursor particles. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention provides a microreactor for synthesizing a precursor of a lithium battery cathode material, comprising a reaction kettle cylinder body;

[0031] a draft tube arranged inside the reaction kettle cylinder body;

[0032] a stirring shaft extending into the draft tube; a stirring device is arranged on the stirring shaft;

[0033] A plurality of openings are provided on the barrel wall of the draft tube.

[0034] Figure 1 Schematic structural diagram of the microreactor provided by the present invention;

[0035] Among them, 1 - motor, 2 - salt inlet pipe, 3 - complexing agent inlet pipe, 4 - reaction kettle cylinder, 5 - draft tube, 6 - overflow port, 7 - opening, 8 - stirring shaft, 9 - stirring blade, 10 - precipitating agent inlet pipe, 11 - additive inlet pipe, 12 - pH monitoring instrument, 13 - pH meter, 14 - temperature monitoring instrument, 15 - temperature sensor.

[0036] By using the microreactor provided by the present invention, the particle size in the precursor synthesis process can be controllable and uniform, the morphology is regular, and the tap density is high, which can improve the structural stability of the cathode material and enhance the cycling performance of the cathode material; the microreactor synthesis reduces the primary particle layer spacing of the cathode material precursor, increases the specific surface area and tap density of the material, reduces the interfacial internal resistance during cycling, improves the rate performance of the cathode material, and at the same time the material compaction density is increased, thereby improving the energy density of the lithium-ion battery. Moreover, the precursor synthesized by the present invention is more conducive to the sintering of single crystal materials in the later stage and is suitable for industrial mass production.

[0037] In the present invention, the microreactor includes a reaction kettle cylinder 4, and the cylinder of the reaction kettle is equipped with a cylinder cover; the reaction kettle cylinder is the place for raw material mixing and chemical reaction; in the present application, the volume of the reaction kettle cylinder is preferably 50L to 5000L, more preferably 50 to 500L; the height of the reaction kettle cylinder is preferably 20 to 3000 cm, more preferably 50 to 300 cm. The reaction kettle cylinder is divided into two types: axial and radial.

[0038] In the present invention, the microreactor includes a draft tube 5; the draft tube is arranged in the reaction kettle cylinder; the shape of the draft tube is cylindrical. A plurality of openings 7 are provided on the barrel wall of the draft tube; the plurality of openings are mirror-symmetrically distributed around the axis of the stirring shaft. The opening is square.

[0039] Figure 2 Schematic diagram of the opening on the microreactor provided by the present invention; among them, 17 - inner diameter D of the reaction kettle cylinder, 18 - side wall gap between the draft tube and the reaction kettle cylinder, 19 - height gap H between two adjacent openings, 20 - inner diameter d of the draft tube, 21 - height h of the opening.

[0040] In the present invention, the following relationships are satisfied among the diameter D of the reaction kettle cylinder, the side wall gap L between the draft tube and the reaction kettle, the height gap H between adjacent openings, the inner diameter d of the draft tube, and the height h of the opening:

[0041] d = (1 / 2 to 9 / 10)D; L = (D - d) / 2; H = h = (1 / 10 to 1 / 2)d. Preferably, the ratio of D:d:L:H:h is (20 to 250):(10 to 255):(10 to 25):(1 to 110):(1 to 110).

[0042] In a specific embodiment of the present invention, the inner diameter D of the reaction kettle is 20 to 250 cm, the height of the reaction kettle is 20 to 3000 cm, the gap between the side wall of the draft tube and the reaction kettle body is 10 to 25 cm; the inner diameter d of the draft tube is 10 to 225 cm; the height of the draft tube is 25 to 150 cm, and the side length of the opening on the draft tube is 1 to 110 cm.

[0043] In the present invention, the microreactor includes a stirring shaft 8 extending into the draft tube; a stirring device is provided on the stirring shaft, and the stirring device is preferably a stirring paddle 9. The stirring shaft uses an electric motor as a driving device. A plurality of the stirring devices are installed on the stirring shaft, and the plurality of stirring devices are arranged in sequence along the axis of the stirring shaft. The number of the plurality of stirring devices is preferably 1 to 16. The number of layers of the stirring device is 1 to 16 layers.

[0044] In the present invention, along the height direction of the reaction kettle body, at least one opening is provided between two adjacent stirring devices; preferably, at least a pair of mirror-image distributed openings are provided between two adjacent stirring devices; the ratio of the number of layers of the opening to the number of layers of the stirring device is preferably 1:1. In a specific embodiment, the number of layers of the centrally mirror-image distributed openings is 2 layers, 6 layers or 5 layers.

[0045] In the present invention, a salt injection port, a complexing agent injection port, a precipitating agent injection port and an additive injection port are provided on the cover of the microreactor kettle body. The salt inlet pipe 2 extends into the draft tube through the salt injection port. The complexing agent inlet pipe 3 extends into the draft tube through the complexing agent injection port. The precipitating agent inlet pipe 10 extends into the draft tube through the precipitating agent injection port. The additive inlet pipe 11 extends into the draft tube through the additive injection port. The microreactor further includes a pH monitoring instrument 12 and a pH meter 13. The pH monitoring instrument is outside the reaction kettle body, and the pH meter connected to the pH monitoring instrument is inside the draft tube. The microreactor further includes a temperature monitoring instrument 14 and a temperature sensor 15 connected to the temperature monitoring instrument. The temperature monitoring instrument is provided outside the reaction kettle body, and the temperature sensor is provided inside the draft tube.

[0046] An overflow port 6 is provided on the side wall of the reaction kettle body, and the overflow port is used for continuous reaction and continuous discharging.

[0047] With the assistance of a draft tube having multiple openings, the microreactor provided by the present invention enables the establishment of multiple internal and external circulations inside the reactor. Under the synergistic action in multiple aspects, the material size can be reduced, making the reaction more sufficient and uniform, thereby achieving controllable particle size. The microreactor can also improve the utilization rate of metal precipitation in coprecipitation. The role of multi-stage reaction also increases the energy in the reaction, promotes the progress of the reaction, and is conducive to the acceleration of the coupling speed of different metal ions under the action of stirring dispersion and internal circulation during the coprecipitation process of multiple metal ions. Metal ions with different deposition coefficients can accurately generate more crystal nuclei in proportion under the combined action of double stirring and circulating fluid, inhibit the growth of crystal nuclei, and avoid excessive agglomeration between secondary particles during the coprecipitation process and the aging process; the components are uniform, the particle size is controllable, the tap density is high, the crystallinity is high, the metal utilization rate during the coprecipitation process is almost 100%, and it can implement a large-scale preparation process for the precursor of the cathode material. At the same time, the microreactor reduces the interlayer spacing of the primary particle layer of the cathode material precursor, thereby improving the performance of the prepared material.

[0048] The present invention provides a method for preparing a precursor of a cathode material for a lithium battery, comprising the following steps:

[0049] Mix a nickel compound, a cobalt compound, a manganese compound and water to obtain a mixed salt solution;

[0050] Add the mixed salt solution, a precipitating agent, a complexing agent and an auxiliary agent into the microreactor described in the above technical solution, and carry out a coprecipitation reaction under stirring conditions to obtain a nickel-cobalt-manganese precursor; during the coprecipitation reaction, the solid content and stirring speed in the reaction kettle system are controlled to form a vortex of the material in the reaction kettle cylinder;

[0051] Age and wash the nickel-cobalt-manganese precursor to obtain a precursor of a cathode material for a lithium battery.

[0052] In the present invention, a nickel compound, a cobalt compound, a manganese compound and water are mixed to obtain a mixed salt solution. In the present invention, the nickel compound is preferably selected from nickel sulfate; the cobalt compound is selected from cobalt sulfate; the manganese compound is selected from manganese sulfate.

[0053] The total molar concentration of nickel salt, cobalt salt and manganese salt in the mixed salt solution is preferably 0.5 - 5 mol / L, more preferably 1.5 - 4 mol / L, and most preferably 2.5 - 3 mol / L. The molar ratio of the nickel compound, the cobalt compound and the manganese compound is preferably (0.5 - 9):(0.5 - 3):(0.5 - 9), more preferably (3 - 8):(0.5 - 2.5):(1 - 7).

[0054] After obtaining the mixed salt solution, the present invention adds the mixed salt solution, precipitant solution, complexing agent, and auxiliary agent into the microreactor described in the above technical solution, and performs a coprecipitation reaction under stirring conditions to obtain a nickel-cobalt-manganese precursor.

[0055] In the present invention, the precipitant solution is selected from one or more of sodium hydroxide solution, sodium carbonate solution, ammonium carbonate solution, and ammonium bicarbonate solution; the concentration of the precipitant solution is preferably 0.5 - 5 mol / L, more preferably 1.5 - 4 mol / L, and most preferably 2.5 - 3 mol / L.

[0056] In the present invention, the complexing agent is selected from one or more of ammonia water, urea, and sodium citrate. The concentration of the complexing agent is 0.5 - 4 mol / L, more preferably 1.5 - 4 mol / L, and most preferably 2.5 - 3 mol / L.

[0057] In the present invention, the pH value of the coprecipitation reaction is 7 - 12, preferably 8 - 11, and more preferably 9 - 10; the time of the coprecipitation reaction is preferably 10 - 120 h, more preferably 30 - 100 h, and most preferably 50 - 80 h. The constant temperature water bath temperature of the cylinder, that is, the temperature of the coprecipitation, is preferably 50 - 65 °C, more preferably 55 - 60 °C. The stirring rate is preferably 200 - 100 rpm, more preferably 250 - 850 rpm. In the coprecipitation reaction, by controlling the solid content and stirring speed in the reaction kettle system, the material forms a vortex in the reaction kettle cylinder; the schematic diagram of the vortex is as Figure 3 shown, and 16 is the schematic diagram of the vortex flow direction.

[0058] Age the nickel-cobalt-manganese precursor to obtain a precursor for a lithium battery cathode material.

[0059] In the reaction kettle, the material reaches a certain solid content, and the mixed slurry is placed in an aging kettle to start aging; the aging time is preferably 10 - 48 h, more preferably 20 - 40 h, and most preferably 25 - 35 h.

[0060] In the present invention, during the coprecipitation reaction and aging, stirring is continuously carried out; and the coprecipitation reaction can be continuous or batch.

[0061] The present invention preferably washes, dehydrates, and dries the aging product for use as a precursor for a lithium battery cathode material.

[0062] The present invention prepares a precursor for a lithium battery cathode material by a coprecipitation method; the coprecipitation reaction is synthesized using a microreactor; the coprecipitated product is washed with water, dehydrated, and dried to obtain the required precursor for the lithium battery cathode material; the above precursor is mixed with a lithium source and sintered to obtain a lithium ion battery cathode material. By using this process method, the coprecipitation reactor is micro-zoned, the fluid system in the reactor has good uniformity, the precursor for the lithium ion battery cathode material obtained has controllable and uniform particle size, regular morphology, high tap density, and good crystallinity; the lithium ion battery cathode material obtained after lithium mixing and sintering modification has high compaction, high rate performance, and good cycle stability, which is an important choice for high energy density and long life lithium ion batteries.

[0063] The present invention provides a lithium ion battery cathode material, which is prepared by sintering a precursor for a lithium battery cathode material and a lithium salt prepared by the preparation method described in the above technical solution.

[0064] In the present invention, the metering ratio of the precursor for the lithium battery cathode material to the lithium salt is 1:1 to 1.5. The sintering temperature is 735 to 975 °C, and the sintering time is 8 to 20 h.

[0065] In order to further illustrate the present invention, the following examples are used to describe in detail a microreactor and a preparation method and application of a precursor for a lithium battery cathode material provided by the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0066] Example 1

[0067] A preparation method for a lithium-rich manganese-based ternary material precursor includes the following steps:

[0068] (1) Weigh a certain amount of nickel sulfate, cobalt sulfate, manganese sulfate, and additive magnesium sulfate respectively, and stir and dissolve them in deionized water according to the molar ratio concentration in the chemical formula Li(Li 0.5 Ni 0.25 Co 0.15 Mn 0.6 Mg 0.05 )O2 to prepare a 2 mol / L mixed salt solution;

[0069] (2) Weigh a certain amount of sodium carbonate, stir and dissolve it in deionized water to prepare a 2 mol / L sodium carbonate solution for use as a precipitant;

[0070] (3) Measure a certain amount of 25% ammonia water, dilute it with deionized water, and prepare a 0.2 mol / L ammonia water solution for use as a complexing agent;

[0071] (4) The three solutions prepared in the above steps (1) - (3) are respectively added dropwise into a 200 L microreactor at a certain rate. Among them, the rate of salt is controlled at 100 mL / min, and the rate of ammonia water is controlled at 35 mL / min. The inner diameter D of the reactor is 75 cm, the height of the reactor is 80 cm, the gap L between the draft tube and the side wall of the reactor is 10 cm, the inner diameter d of the draft tube is 55 cm, and the height of the draft tube is 60 cm. The opening of the draft tube is 15 cm × 15 cm, with two layers of openings and the opening spacing is 15 cm. The pH value of the reaction system in the reactor is controlled at 8.5 by the flow rate of the base. During the reaction process, the complexing agent in step (3) is intermittently added. The system in the reactor is heated to 60 °C at a constant temperature by direct electric heating;

[0072] (5) The rotation speed of the stirring paddle of the reactor is controlled at 750 r / min. The reaction in the above reaction system lasts for 50 h, and the precursor is aged in the aging kettle for 2 h; the precursor obtained from the discharge of the aging kettle is washed and dried to obtain the precursor of the lithium-rich manganese-based cathode material.

[0073] (6) The above-mentioned aged product is washed with water multiple times, dehydrated, and dried to obtain the precursor of the lithium-rich manganese-based ternary material Ni 0.25 Co 0.15 Mn 0.6 Mg 0.05 CO3.

[0074] The tap density of the particles of the lithium-rich manganese-based ternary material precursor is 2.18 g / ml, and D 50 is 8.5 μm. The particle size distribution and morphological characteristics of the obtained Ni 0.25 Co 0.15 Mn 0.6 Mg 0.05 CO3 precursor particles are as shown in Figure 4 and Figure 5 respectively. It can be seen from Figure 4 and Figure 5 that the use of a microreactor to prepare the precursor has a high sphericity, and this method effectively controls the excessive growth of the precursor particle size during the synthesis process. The above-mentioned precursor particles are mixed with lithium carbonate with a lithiation ratio (the lithiation ratio is the stoichiometric ratio of lithium to the precursor mixture) of 1.5, and without any other doping and coating modification treatments, they are directly sintered at 825 °C for 18 h and then assembled into a half-cell for electrochemical performance testing. The results show that the initial discharge capacity of the cathode material reaches 301 mA h / g, and the cathode material can maintain excellent cycling performance during the cycling process. The capacity retention rate of the half-cell is 87.9% after 500 cycles of charge and discharge at 0.5C.

[0075] Example 2

[0076] A preparation method of a high-nickel ternary material precursor, comprising the following steps:

[0077] (1) Weigh a certain amount of nickel sulfate, cobalt sulfate, manganese sulfate, and additives magnesium sulfate and ammonium aluminate respectively; according to the molar ratio concentration in the chemical formula Li 1.02 Ni 0.8 Co 0.05 Mn 0.1 Mg 0.02 Al 0.03 )O2, stir and dissolve in deionized water to prepare a mixed salt solution with a concentration of 2 mol / L;

[0078] (2) Weigh a certain amount of sodium carbonate, stir and dissolve it in deionized water to prepare a sodium hydroxide solution with a concentration of 4 mol / L for use as a precipitating agent;

[0079] (3) Measure a certain amount of 25% ammonia water, dilute it with deionized water, and prepare an ammonia water solution with a concentration of 2.2 mol / L for use as a complexing agent;

[0080] (4) Add the three prepared solutions in steps (1) to (3) above at a certain rate respectively. Among them, control the salt rate at 1 L / min and the ammonia water rate at 350 mL / min and drop them into a 2000 L microreactor. The inner diameter D of the reaction kettle is 125 cm, the height of the reaction kettle is 180 cm, the gap L between the draft tube and the reaction kettle is 25 cm, the inner diameter d of the draft tube is 75 cm, the height of the draft tube is 160 cm, the opening of the draft tube is 10 cm × 10 cm, there are 6 layers of openings, and the opening spacing is 15 cm. And control the pH value of the reaction system in the reaction kettle at 11.5 by the flow rate of the base, intermittently add the complexing agent in step (3) during the reaction process, and use the direct electric heating method to keep the system in the reaction kettle at a constant temperature of 50 °C;

[0081] (5) Control the rotation speed of the stirring paddle of the reaction kettle at 250 r / min, react in the above reaction system for 50 h, age the precursor in the aging kettle for 2 h, and wash and dry the precursor obtained from the discharge of the aging kettle to obtain the high-nickel ternary material precursor.

[0082] (6) Wash the above aging product with water multiple times, dehydrate and dry it to obtain the high-nickel ternary material precursor Ni 0.8 Co 0.05 Mn 0.1 Mg 0.02 Al 0.03 (OH)2.

[0083] The tapped density of the particles of the lithium-rich manganese-based ternary material precursor is 2.08 g / ml, D 50 is 10.5 μm. Obtain Ni 0.8 Co 0.05 Mn0.1 Mg 0.02 Al 0.03 The (OH)2 precursor particles have uniform particle size distribution and morphological characteristics. The micro-reactor is used to prepare the precursor with high sphericity, and this method effectively controls the rapid growth of the precursor particle size during the synthesis process. After the above-mentioned precursor particles are mixed with lithium hydroxide with a lithiation ratio (lithiation ratio is the stoichiometric ratio of lithium to precursor) of 1.02, no other modification treatments such as doping and coating are performed. After being directly sintered at 755°C for 18 hours, they are assembled into half-cells for electrochemical performance testing. The results show that the first discharge capacity of the positive electrode material reaches 218mA h / g, and the positive electrode material can maintain excellent cycle performance during the cycle process. The capacity retention rate of the half-cell is 92.5% after 500 cycles of charge and discharge at 0.5C.

[0084] Example 3

[0085] A method for preparing a ternary material precursor comprises the following steps:

[0086] (1) Weigh a certain amount of nickel sulfate, cobalt sulfate and manganese sulfate respectively, and mix them according to the chemical formula Li 1.05 Ni 0.5 Co 0.3 Mn 0.2 The molar concentration of O2 was stirred and dissolved in deionized water to prepare a 2 mol / L mixed salt solution;

[0087] (2) weighing a certain amount of sodium carbonate, stirring and dissolving it in deionized water to prepare a 5 mol / L sodium hydroxide solution, which is used as a precipitant;

[0088] (3) taking a certain amount of 25% ammonia water, diluting it with deionized water, and preparing a 2.5 mol / L ammonia solution for use as a complexing agent;

[0089] (4) The three prepared solutions in 1 to 3 above are added dropwise to a 600L micro-grid reactor at a certain rate, wherein the salt rate is controlled at 450mL / min and the ammonia rate is controlled at 250mL / min. The inner diameter D of the reactor is 95cm, the height of the reactor is 100cm, the gap L between the guide tube and the reactor is 15cm, the inner diameter d of the guide tube is 65cm, the height of the guide tube is 60cm, the opening of the guide tube is 5cm×5cm, there are 5 layers of openings, and the spacing between the openings is 5cm. The pH value of the reactor reaction system is controlled to 10.5 by the flow rate of alkali. The complexing agent in the above 3 is added intermittently during the reaction process. The system in the reactor is heated to 45°C by direct electric heating;

[0090] (5) Controlling the stirring speed of the reactor to 850 r / min, the reaction system is reacted for 150 h, and the precursor is aged in the aging reactor for 2 hours. The precursor obtained by discharging the aging reactor is washed and dried to obtain the high-nickel ternary material precursor;

[0091] (6) The aged coprecipitated product is washed with water for multiple times, dehydrated and dried to obtain a high nickel ternary material precursor Ni 0.5 Co 0.3 Mn 0.2 (OH)2.

[0092] The particle tap density of the ternary material precursor is 2.28 g / ml, D 50 The thickness of Ni is 11.5 μm. 0.5 Co 0.3 Mn 0.2 The (OH)2 precursor particles have uniform particle size distribution and morphological characteristics. The micro-reactor is used to prepare the precursor with high sphericity, and this method effectively controls the rapid growth of the precursor particle size during the synthesis process. After the above-mentioned precursor particles are mixed with lithium carbonate with a lithiation ratio (lithiation ratio is the stoichiometric ratio of lithium to precursor) of 1.05, no other modification treatments such as doping and coating are performed. After being directly sintered at 855°C for 12 hours, they are assembled into half-cells for electrochemical performance testing. The results show that the first discharge capacity of the positive electrode material reaches 178mAh / g, and the positive electrode material can maintain excellent cycle performance during the cycle process. The capacity retention rate of the half-cell is 90.9% after 500 cycles of charge and discharge at 1C.

[0093] It can be seen from the above embodiments that the present invention provides a micro-reactor for the synthesis of positive electrode material precursors for lithium batteries, comprising a reactor cylinder; a guide cylinder installed in the reactor cylinder; a stirring shaft equipped with a stirring device extending into the guide cylinder; and a plurality of openings are provided on the cylinder wall of the guide cylinder. The micro-reactor provided by the present invention, with the assistance of the guide cylinder with multiple openings, enables multiple internal and external circulations to be established inside the reactor, and under the synergistic effect of multiple aspects, the material size can be reduced, so that the reaction is more sufficient and uniform, thereby achieving controllable particle size. The positive electrode material for lithium batteries prepared by the above-mentioned micro-reactor, which is obtained after lithium mixing and sintering modification, has high compaction, high rate and good cycle stability, and is an important choice for high energy density and long life lithium-ion batteries. The experimental results show that the tap density of the precursor is 2.05-2.28g / ml; D 50 The initial discharge capacity of the battery reaches 178-301 mAh / g, and the capacity retention rate after 500 cycles of charge and discharge at 0.5C is 87.9-92.5%.

[0094] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A microchannel reactor for synthesizing a precursor of a lithium battery cathode material, comprising a reaction kettle cylinder body; A draft tube disposed inside the reaction kettle cylinder body; A stirring shaft extending into the draft tube; a stirring device is provided on the stirring shaft; a plurality of the stirring devices are installed on the stirring shaft, and the plurality of the stirring devices are arranged in sequence along the axis of the stirring shaft; A plurality of openings are provided on the cylinder wall of the draft tube; The plurality of openings are mirror-symmetrically distributed with the axis of the stirring shaft as the center; along the height direction of the reaction kettle cylinder body, at least one opening is provided between two adjacent stirring devices; The following relationships are satisfied among the diameter D of the reaction kettle cylinder body, the clearance L between the draft tube and the side wall of the reaction kettle, the height clearance H between adjacent openings, the inner diameter d of the draft tube, and the height h of the opening: d = (1 / 2 to 9 / 10)D; L = (D - d) / 2; H = h = (1 / 10 to 1 / 2)d; The ratio of the number of layers of the opening to the number of layers of the stirring device is 1:

1.

2. The microchannel reactor according to claim 1, wherein The number of layers of the stirring device is 2 to 16 layers, excluding 1 layer.

3. A method for preparing a precursor of a lithium battery cathode material, comprising the following steps: Mix a nickel compound, a cobalt compound, a manganese compound and water to obtain a mixed salt solution; Add the mixed salt solution, a precipitating agent, a complexing agent and an auxiliary agent into the microreactor according to any one of claims 1 to 2, and carry out a coprecipitation reaction under stirring conditions to obtain a nickel cobalt manganese precursor; during the coprecipitation reaction, control the solid content and stirring speed in the reaction kettle system to form a vortex of the material in the reaction kettle cylinder; Age and wash the nickel cobalt manganese precursor to obtain a precursor for a lithium battery cathode material.

4. The preparation method according to claim 3, wherein The pH value of the coprecipitation reaction is 7 to 12; the time of the coprecipitation reaction is 10 to 120 h; The aging time is 10 to 48 h.

5. A lithium ion battery cathode material is prepared by sintering a precursor of a lithium battery cathode material and a lithium salt prepared by the preparation method according to any one of claims 3 to 4.

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