Monocrystal ternary positive electrode material with excellent low-temperature performance and preparation method thereof

Abstract

The invention provides a single-crystal ternary positive electrode material and a preparation method thereof. The method comprises the following steps: (1) uniformly mixing a lithium source, one or more compounds containing doping elements and a ternary positive electrode material precursor prepared by using a micro-channel reactor to obtain a mixed material; (2) carrying out primary calcination on the mixed material obtained in the step (1) in an oxygen-containing atmosphere to obtain a blocky material; (3) crushing the blocky material obtained in the step (2) to obtain a doped ternary positive electrode material matrix; and (4) uniformly mixing the doped ternary positive electrode material matrix obtained in the step (3) with one or more coating element-containing compounds, and carrying out secondary calcination to obtain the single-crystal ternary positive electrode material. The single-crystal ternary positive electrode material has the characteristics of small primary particle size, relatively high specific capacity, good rate characteristic and high low-temperature capacity retention rate.

Description

Technical Field

[0001] The invention belongs to the field of lithium-ion battery materials and relates to a single-crystal ternary positive electrode material with excellent low-temperature performance and a preparation method thereof. Background Art

[0002] Compared with traditional chemical energy storage batteries, although lithium-ion batteries have obvious advantages in energy density and cycle life, they still have a lot of gaps in temperature adaptability. In high-altitude areas and cold winter environments, the insufficient low-temperature discharge performance of lithium-ion batteries leads to a serious reduction in the range of electric vehicles, which limits the promotion of electric vehicles in cold areas.

[0003] Chinese patent application CN202310089289.8 discloses a small-particle-size single-crystal cathode material and its preparation method and lithium-ion battery, which discloses: lithium source compound, nickel source compound, cobalt source compound and manganese source compound are taken according to the stoichiometric ratio, mixed with the aqueous solution of complexing agent A, and reacted to obtain a mixed solution; an aqueous solution of complexing agent B is added to the mixed solution, and a sol is reacted; the sol is heated, evaporated and concentrated to form a gel; the gel is calcined step by step to obtain a small-particle-size single-crystal cathode material. The small-particle-size single-crystal cathode material prepared by it has the characteristics of highly flat and smooth single crystal particles, and the particle size D50 is 1.5 to 5 μm. After being assembled into a lithium-ion battery, the contact surface between the particle surface and the electrolyte is reduced, and the corresponding side reactions of the cathode material and the electrolyte are significantly reduced, effectively reducing the heat release and gas release caused by the side reactions, so that the battery has better high-temperature safety performance, high-temperature rate performance and charge and discharge voltage platform. This document does not involve the low-temperature discharge performance of lithium-ion batteries. Moreover, the document uses the sol-gel method to synthesize small-particle ternary single crystal cathode materials, which has a long synthesis cycle, high organic solvent costs, and improper temperature treatment during heat treatment can easily leave excess carbon, which in turn causes product performance degradation. Overall, the sol-gel method is difficult to industrialize. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a simple, easy-to-operate and industrializable method for preparing single-crystal ternary positive electrode materials. The prepared single-crystal ternary positive electrode materials have the characteristics of small primary particle size, high specific capacity, good rate characteristics and high low-temperature capacity retention rate.

[0005] Specifically, the present invention provides a method for preparing a single crystal ternary cathode material, the method comprising the following steps:

[0006] (1) uniformly mixing a lithium source, one or more compounds containing doping elements, and a ternary cathode material precursor prepared using a microchannel reactor to obtain a mixed material;

[0007] (2) calcining the mixed material obtained in step (1) in an oxygen-containing atmosphere to obtain a bulk material;

[0008] (3) crushing the bulk material obtained in step (2) to obtain a crushed material, i.e., a doped ternary positive electrode material matrix;

[0009] (4) The doped ternary cathode material matrix obtained in step (3) and one or more compounds containing coating elements are uniformly mixed and subjected to secondary calcination to obtain the single crystal ternary cathode material.

[0010] In one or more embodiments, the ratio of the amount of lithium element in the lithium source to the amount of the ternary cathode material precursor is (1-1.1):1, preferably (1.02-1.06):1.

[0011] In one or more embodiments, the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium nitrate and lithium acetate, preferably lithium hydroxide.

[0012] In one or more embodiments, the chemical formula of the ternary cathode material precursor is Ni x Co y M z (OH)2 or Ni x Co y M z O m H n , wherein M is Al or Mn, 0.3≤x≤0.7, 0.05≤y≤0.3, 0.05≤z≤0.4, x+y+z=1, m>0, n>0, 2m-n=2; preferably, 0.6≤x≤0.7, 0.05≤y≤0.1, 0.2≤z≤0.3.

[0013] In one or more embodiments, the doping element is selected from one or more of Zr, Ti, Al, Y, B, W, Mg, Mo and Nb, preferably Zr.

[0014] In one or more embodiments, the compound containing the doping element is selected from one or more of oxides and hydroxides of the doping element.

[0015] In one or more embodiments, the mass of each compound containing a doping element is 0.1 to 1 wt % of the mass of the ternary positive electrode material precursor.

[0016] In one or more embodiments, in step (1), the ternary cathode material precursor is generated by co-precipitation reaction of nickel salt, cobalt salt and aluminum salt or nickel salt, cobalt salt and manganese salt in the presence of a precipitant and a complexing agent in a microchannel reactor.

[0017] In one or more embodiments, the microchannel reactor is a valve-type microreactor, which includes a first feed port, a second feed port, a first feed pressure regulating device, a second feed pressure regulating device, a reaction chamber and a discharge port, wherein the first feed port is connected to the reaction chamber through a first flow channel, and the second feed port is connected to the reaction chamber through a second flow channel. The first feed pressure regulating device is arranged on the first flow channel between the first feed port and the reaction chamber, and is used to control the feed pressure of the first feed port. The second feed pressure regulating device is arranged on the second flow channel between the second feed port and the reaction chamber, and is used to control the feed pressure of the second feed port. The discharge port is connected to the reaction chamber, and the nickel salt, cobalt salt and aluminum salt or nickel salt, cobalt salt and manganese salt are fed to the reaction chamber through the first flow channel, and the precipitant and complexing agent are fed to the reaction chamber through the second flow channel.

[0018] In one or more embodiments, the end of the first flow channel and the end of the second flow channel are provided with a plurality of micropores and / or slits distributed in an annular shape, so that the jets ejected from the end of the first flow channel and the end of the second flow channel correspond one to one, and real-time collision and mixing occur.

[0019] In one or more embodiments, the primary calcination is performed in an oxygen atmosphere or a mixed atmosphere of oxygen and air.

[0020] In one or more embodiments, the isothermal temperature of the primary calcination is 700 to 1000°C.

[0021] In one or more embodiments, the constant temperature time of the primary calcination is 4 to 12 hours.

[0022] In one or more embodiments, the heating rate of the primary calcination is 0.5° C. / min to 4° C. / min.

[0023] In one or more embodiments, the coating element is selected from one or more of Al, Zr, Ti, W, Nb, B, Ce and Mo, preferably W and Al.

[0024] In one or more embodiments, the compound containing the coating element is one or more selected from oxides and hydroxides of the coating element.

[0025] In one or more embodiments, the mass of each compound containing the coating element is 500 to 5000 ppm of the mass of the doped ternary positive electrode material.

[0026] In one or more embodiments, the isothermal temperature of the secondary calcination is 250-600°C.

[0027] In one or more embodiments, the constant temperature time of the secondary calcination is 4 to 12 hours.

[0028] The present invention also provides a single crystal ternary positive electrode material prepared by the method described in any embodiment of the present invention.

[0029] The invention also provides a single crystal ternary positive electrode material.

[0030] In one or more embodiments, the average primary particle size of the single crystal ternary cathode material is 0.8 to 1.8 μm.

[0031] In one or more embodiments, in the single crystal ternary positive electrode material, the percentage of primary particles with a particle size greater than 3 μm in the total number of primary particles is ≤5%.

[0032] In one or more embodiments, the particle size D50 of the single crystal ternary positive electrode material is 1 to 3 μm.

[0033] In one or more embodiments, the particle size D90 of the single crystal ternary positive electrode material is 3 to 6.5 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of a valved microreactor in some embodiments of the present invention. Figure 1 In the figure, 201 is the first feed inlet, 202 is the second feed inlet, 203 is the second feed pressure regulating device, 204 is the first feed pressure regulating device, 205 is the reaction chamber, and 206 is the discharge port.

[0035] Figure 2 Schematic diagram of a system for preparing a cathode material precursor in some embodiments of the present invention. Figure 2 In the figure, 101 is a first feeding system, 102 is a second feeding system, 103 is a connecting pipeline, 104 is a valve type microreactor, 105 is a vacuum negative pressure tank, 106 is a vacuum pump, and 107 is an aging device.

[0036] Figure 3 Schematic diagram of a system for preparing a cathode material precursor in some embodiments of the present invention. Figure 3 In the figure, 101 is the first feeding system, 102 is the second feeding system, 104 is the valve type microreactor, 105 is the vacuum negative pressure tank, 106 is the vacuum pump, 107 is the aging device, 108 is the first raw material tank, 109 is the first washing water tank, 301 is the first feeding device, 302 is the first mass flow meter, 303 is the first pressure controller, 304 is the first reversing valve, 110 is the second raw material tank, 111 is the second washing water tank, 401 is the second feeding device, 402 is the second mass flow meter, 403 is the second pressure controller, and 404 is the second reversing valve.

[0037] Figure 4 Schematic diagram of a system for preparing a cathode material precursor in some embodiments of the present invention. Figure 4 Among them, 108 is the first raw material tank, 110 is the second raw material tank, 112 is the third raw material tank, 101 is the first feeding system, 102 is the second feeding system, 103 is the third feeding system, 114 is the first inlet module, 115 is the first heating module, 116 is the second inlet module, 117 is the third inlet module, 119 is the mixing module, 120 is the second heating module, 104 is the valve microreactor, 121 is the outlet module, and 107 is the aging device.

[0038] Figure 5 Schematic diagram of a valved microreactor in some embodiments of the present invention. Figure 5 In the figure, 201 is the first feed port, 202 is the second feed port, 203 is the second feed pressure regulating device, 204 is the first feed pressure regulating device, 205 is the reaction chamber, 206 is the discharge port, 501 is the micropore, and 502 is the slit.

[0039] Figure 6 Schematic diagram of the correspondence between slits and micropores in a valve-type microreactor in some embodiments of the present invention. Figure 6 In the figure, 501 is a microhole and 502 is a slit.

[0040] Figure 7 This is a scanning electron microscope (SEM) image of the single crystal ternary positive electrode material prepared in Example 1.

[0041] Figure 8 This is the SEM image of the ternary positive electrode material prepared in Comparative Example 1.

[0042] Fig. 9 This is the SEM image of the ternary positive electrode material prepared in Comparative Example 2.

[0043] Fig.10 This is the SEM image of the ternary positive electrode material prepared in Comparative Example 3. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0045] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0046] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0047] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0048] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0049] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0050] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0051] The single crystal ternary positive electrode material of the present invention has excellent low-temperature capacity retention. The average particle size of the primary particles of the single crystal ternary positive electrode material of the present invention is 0.8 to 1.8 μm, for example, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm or within the range of any two of the aforementioned values. In the present invention, the primary particle size of the single crystal ternary positive electrode material is measured by scanning electron microscopy (SEM). The particle size D50 of the single crystal ternary positive electrode material of the present invention is 1 to 3 μm, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm or within the range of any two of the aforementioned values. The particle size D90 of the single crystal ternary positive electrode material of the present invention is 3 to 6.5 μm, such as 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.3 μm, 5.4 μm, 5.5 μm, 5.6 μm, 5.7 μm, 5.8 μm, 5.9 μm, 6 μm, 6.5 μm or any two of the above values. The particle size D10 of the single crystal ternary positive electrode material of the present invention can be 0.5 to 1.5 μm, such as 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or any two of the above values. In the present invention, the particle size D50 and particle size D90 of the single crystal ternary positive electrode material are measured using a Malvern laser particle size analyzer. In a preferred embodiment, the percentage of primary particles with a particle size greater than 3 μm in the single crystal ternary positive electrode material of the present invention to all primary particles is ≤5%, for example ≤4%, ≤3%, ≤2.5%, ≤2.3%, ≤2.2%, ≤2.1%, ≤2%, ≤1.5%, ≤1.4%.

[0052] The single crystal ternary cathode material of the present invention is prepared by a method comprising the following steps:

[0053] (1) uniformly mixing a lithium source, one or more compounds containing doping elements, and a ternary cathode material precursor prepared using a microchannel reactor to obtain a mixed material;

[0054] (2) calcining the mixed material obtained in step (1) in an oxygen-containing atmosphere to obtain a bulk material;

[0055] (3) crushing the bulk material obtained in step (2) to obtain a crushed material, i.e., a doped ternary positive electrode material matrix;

[0056] (4) The doped ternary cathode material matrix obtained in step (3) and one or more compounds containing coating elements are uniformly mixed and subjected to secondary calcination to obtain the single crystal ternary cathode material of the present invention.

[0057] In the present invention, in step (1), the ratio of the amount of lithium element in the lithium source to the amount of the substance of the ternary cathode material precursor is (1-1.1):1, preferably (1.02-1.06):1, for example, 1.03:1, 1.04:1, 1.05:1. The lithium source can be selected from one or more of lithium hydroxide, lithium carbonate, lithium nitrate, and lithium acetate, preferably lithium hydroxide.

[0058] The ternary cathode material precursor used in the present invention is a ternary cathode material precursor prepared by a microchannel reactor.

[0059] In the present invention, the chemical formula of the ternary cathode material precursor is Ni x Co y M z (OH)2 or Ni x Co y M z O m H n , M is Mn or Al, 0<x<1, 0<y<1, 0<z<1, x+y+z=1, m>0, n>0, 2m-n=2. The ternary cathode material precursor is in granular form, also known as ternary cathode material precursor particles.

[0060] Preferably, the chemical formula of the ternary cathode material precursor is Ni x Co y M z (OH)2 or Ni x Co y M z O m H n In the invention, 0.3≤x<1, for example, x can be 0.3, 0.4, 0.5, 0.6, 0.63, 0.65, 0.76, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or any two of the foregoing values, and x is preferably 0.3-0.7, more preferably 0.6-0.7; 0<y≤0.3, for example, y can be 0.01, 0.05, 0.07, 0.1, 0.12, 0.15, In the range of 0.2, 0.25, 0.3 or any two of the foregoing values, y is preferably 0.05-0.3, more preferably 0.05-0.1; 0<z≤0.4, for example, 0.01, 0.05, 0.07, 0.1, 0.15, 0.2, 0.25, 0.26, 0.28, 0.3, 0.35, 0.4 or any two of the foregoing values, z is preferably 0.05-0.4, more preferably 0.2-0.3.

[0061] In some preferred embodiments, the chemical formula of the ternary cathode material precursor is Ni x Co y Mz (OH)2, M is Mn or Al, preferably Mn, x is preferably 0.6 to 0.7, for example 0.63 to 0.67, y is preferably 0.05 to 0.1, for example 0.06 to 0.08, and z is preferably 0.2 to 0.3, for example 0.26 to 0.3.

[0062] The ternary cathode material precursor is generated by coprecipitation reaction of nickel salt, cobalt salt and aluminum salt or nickel salt, cobalt salt and manganese salt in the presence of precipitant and complexing agent. The raw materials for preparing the ternary cathode material precursor generally include: a salt solution of nickel cobalt aluminum or nickel cobalt manganese, a precipitant and a complexing agent. Among them, the precipitant and the complexing agent can be mixed and fed, or they can be fed separately. In the present invention, the salt solution of nickel cobalt manganese is a solution containing nickel salt, cobalt salt and manganese salt, and the salt solution of nickel cobalt aluminum is a solution containing nickel salt, cobalt salt and aluminum salt. Nickel salts, cobalt salts, manganese salts and aluminum salts suitable for the present invention can be nickel salts, cobalt salts, manganese salts and aluminum salts known to be used for preparing ternary cathode material precursors, including but not limited to nickel sulfate, cobalt sulfate, manganese sulfate, aluminum sulfate and hydrates thereof. In the salt solution of nickel cobalt aluminum or nickel cobalt manganese, the total concentration of metal ions can be 1.5 to 2.5 mol / L, preferably 1.5 to 2 mol / L.

[0063] The precipitant may be a sodium hydroxide solution. The concentration of the sodium hydroxide solution may be 4 to 10 mol / L, preferably 4 to 8 mol / L. The complexing agent may be an aqueous ammonia solution. The concentration of the aqueous ammonia solution may be 3 to 10 mol / L, preferably 3 to 8 mol / L. In some embodiments, the complexing agent (e.g., aqueous ammonia solution) and the precipitant (e.g., sodium hydroxide solution) are mixed evenly to form a mixed solution, which is then reacted with a salt solution of nickel-cobalt-aluminum or nickel-cobalt-manganese.

[0064] Before the reaction, the reaction raw materials (such as nickel-cobalt-aluminum or nickel-cobalt-manganese salt solution, precipitant, complexing agent, mixed solution of precipitant and complexing agent) are preferably preheated to 30-80°C, preferably 40-70°C.

[0065] The reaction raw materials can be delivered to the microchannel reactor by a feed pump. The feed flow rate of the nickel-cobalt-aluminum or nickel-cobalt-manganese salt solution can be 50 to 400 kg / h, preferably 100 to 300 kg / h. The feed flow rate of the mixed solution of the precipitant and the complexing agent can be 50 to 400 kg / h, preferably 100 to 300 kg / h.

[0066] In some embodiments, a nickel-cobalt-aluminum or nickel-cobalt-manganese salt solution and a mixed solution of a precipitant and a complexing agent are rapidly mixed in a microchannel reactor to undergo a co-precipitation reaction to obtain a ternary cathode material precursor.

[0067] In the present invention, it is preferred to use a ternary cathode material precursor prepared by using a valve microreactor as a place for coprecipitation reaction. In the present invention, the ternary cathode material precursor prepared by using a valve microreactor as a place for coprecipitation reaction is called M ternary cathode material precursor. Therefore, in the present invention, the ternary cathode material precursor used to prepare the single crystal ternary cathode material of the present invention is preferably M ternary cathode material precursor. The use of a valve microreactor to prepare M ternary cathode material precursor has the advantages of high reaction efficiency and reduced control parameters.

[0068] In the present invention, microchannel reactor (also called microreactor) refers to a micro reactor with a characteristic size of 10 to 1000 microns, for example, 10 to 300 microns, manufactured by precision machining technology. The "micro" in microreactor means that the channel of the process fluid is at the micron level, rather than that the overall size of the micro reaction device is small or the output of the product is small.

[0069] The cathode material precursor preparation system (referred to as preparation system) of the present invention can be used to prepare M ternary cathode material precursor. The preparation system of the present invention includes at least two feeding systems and a valve microreactor, wherein the feeding system is used to provide reaction raw materials to the valve microreactor, and the valve microreactor is used to carry out a coprecipitation reaction. In some embodiments, the preparation system of the present invention also includes an aging device, which is used to age the product generated in the valve microreactor. Each feeding system and the valve microreactor and the valve microreactor and the aging device can be connected by a pipeline. The preparation system of the present invention can quickly complete the reaction, reduce the scrap rate, increase the production capacity, completely avoid the amplification effect, shorten the time from research and development to production of the cathode material precursor, and can accurately control the reaction conditions, and can produce products with stable quality and good consistency. The preparation system of the present invention has a simple start-stop reaction, is easy to clean, has a high degree of automation, a stable production process, and is extremely efficient.

[0070] In the present invention, as a reaction device for coprecipitation reaction, the valve-type microreactor can control the pressure of two or more feed liquids, achieve stable feeding and mixing reactions under large flow and high flow rate, ensure that high-concentration reaction products can be quickly removed, and realize continuous reaction without blockage.

[0071] like Figure 1As shown, in the present invention, the valve type microreactor includes a first feed port 201, a second feed port 202, a first feed pressure regulating device 204, a second feed pressure regulating device 203, a reaction chamber 205 and a discharge port 206. The first feed port 202 is connected to the reaction chamber 205 through a flow channel. The second feed port 202 is connected to the reaction chamber 205 through a flow channel. The first feed pressure regulating device 204 is arranged on the flow channel between the first feed port 201 and the reaction chamber 205. The second feed pressure regulating device 203 is arranged on the flow channel between the second feed port 202 and the reaction chamber 205. The discharge port 206 is connected to the reaction chamber 205.

[0072] Jet-type collision occurs between the various liquids entering the reaction chamber through each feed port of the valve microreactor. The end of the flow channel between the feed port and the reaction chamber (for example, the end of the flow channel between the first feed port 201 and the reaction chamber 205, the end of the flow channel between the second feed port 202 and the reaction chamber 205) is provided with a plurality of micropores and / or slits distributed in an annular manner. Herein, the end refers to the end along the flow direction of the feed liquid. Multiple refers to two or more. Annular distribution means that the micropores and / or slits can be regarded as distributed on a ring. Preferably, the micropores and / or slits are arranged so that the jets ejected from the ends of each flow channel correspond one to one, and collide and mix in real time. In some embodiments, the end of the flow channel between the first feed port 201 and the reaction chamber 205 is provided with a micropore, and the end of the flow channel between the second feed port 202 and the reaction chamber 205 is provided with a slit; preferably, the design of the micropores and slits makes the jets ejected from the ends of the two flow channels correspond one to one, and collide and mix in real time. Preferably, the end of the flow channel between the first feed port 201 and the reaction chamber 205 and the end of the flow channel between the second feed port 202 and the reaction chamber 205 are arranged so that materials ejected from the two flow channel ends collide tangentially in the reaction chamber 205 .

[0073] In the present invention, the first feed pressure regulating device 204 and the second feed pressure regulating device 203 are respectively used to control the feed pressure of the first feed port 210 and the second feed port 202, so that the materials of the two feed ports can be sprayed into the reaction chamber 205 according to the expected pressure, flow rate and flow rate. In a preferred embodiment, the materials of the two feed ports are sprayed into the reaction chamber 205 through the micropores and / or slits distributed in an annular shape according to the expected pressure, flow rate and flow rate, and the spray trajectories of the two materials in the reaction chamber 205 after passing through the micropores and / or slits correspond to each other, and a real-time tangential collision occurs to achieve uniform mixing and reaction, and then the product after the reaction flows out quickly through the discharge port 206 under the pressure and the rear negative pressure that preferably exists. In some embodiments, the first feed pressure regulating device or the second feed pressure regulating device includes a pressure valve, and the pressure valve automatically connects the flow channel between the feed port and the reaction chamber when the feed pressure reaches a certain value. In other embodiments, the first feed pressure regulating device or the second feed pressure regulating device includes a pressure gauge and a valve, and the pressure gauge monitors the feed pressure. When the feed pressure reaches a certain value, the pressure gauge directly controls the valve, or controls the valve through other devices such as a numerical control system to connect the flow channel between the feed port and the reaction chamber. In other embodiments, the first feed pressure regulating device or the second feed pressure regulating device also includes a booster pump. When the feed pressure does not reach the set value, the booster pump pressurizes the feed liquid so that the feed pressure reaches the required value. The flow rate and flow velocity of the feed liquid can be adjusted by regulating the pressure of the feed liquid.

[0074] In the present invention, Figure 1 As shown, the reaction chamber 205 is preferably semi-ellipsoidal, and the discharge port 206 is preferably bell-bottomed. The bell-bottomed discharge port 206 is connected to the opening of the semi-ellipsoidal reaction chamber 205, so that high-concentration reaction products can be quickly discharged, and continuous reaction can be achieved without blockage.

[0075] The valve-type microreactor in the present invention realizes stable feeding and mixing reaction under large flow and high flow rate by setting the first feeding pressure regulating device 204 and the second feeding pressure regulating device 203; by setting a plurality of micropores and / or slits, the jet flow collision route is reasonable, the micropore jet flow corresponds to the slit jet flow one by one, and the collision and mixing are carried out in real time, so that a very high mixing and reaction effect can be achieved in the reaction chamber 205; the reaction chamber 205 is designed to be semi-ellipsoidal, and the discharge port 206 is in a bell-bottomed release state. The reasonable design can ensure that the high-concentration reaction products can be quickly discharged, and continuous reaction can be achieved without blockage.

[0076] The valve type microreactor in the present invention may include a T-type microchannel reactor or a cluster microchannel reactor.

[0077] In the present invention, the feeding system includes a feeding device that can accurately, evenly and stably realize solution filtration, metering, pressure regulation, and liquid delivery according to the pipeline and valve direction. In some embodiments, the feeding system includes a feeding device, a mass flow meter, a pressure controller and a valve, the valve includes an inlet and a first outlet, and the feeding system also includes an inlet pipeline connected to the inlet of the valve and a first outlet pipeline connected to the first outlet of the valve, the feeding device, the mass flow meter and the pressure controller are arranged on the inlet pipeline, and the valve communicates with the inlet pipeline and the first outlet pipeline when the flow detected by the mass flow meter and the pressure detected by the pressure controller meet the set value. The feeding device may include a gear feeding device or a delivery pump. The delivery pump may be a gear pump, a diaphragm pump or a peristaltic pump. Each feeding system may be the same or different. The first outlet pipeline of the feeding system may be directly connected to the valve microreactor, or may be connected to other devices, systems or modules (such as heating modules, mixing modules) arranged between the feeding system and the valve microreactor. The inlet pipeline of the feeding system may be connected to a raw material tank or a washing water tank. The valve may be a reversing valve, including two or more outlets. Each outlet of the valve may be connected to an outlet pipe. The second outlet pipe connected to the second outlet of the valve may be connected to a raw material tank or a washing water tank, so that the material flow or pressure does not meet the set requirements and returns to the raw material tank or the washing water tank.

[0078] In the present invention, the aging device is a place where the reaction product of the valve-type microreactor is further aged. The aging device applicable to the present invention can be an aging device commonly used in the art, such as an aging kettle.

[0079] The preparation system of the present invention preferably includes a negative pressure system arranged between the valve type microreactor and the aging device. The negative pressure system is used to form a negative pressure at the outlet end of the valve type microreactor. All devices or device combinations that can ensure that the reaction products of the mixed reaction of the reactants in the microchannel reactor and the outlet end can be timely removed under the action of the feed pressure and the rear end negative pressure, and ensure that the microchannel reactor can run smoothly without clogging under the reaction condition line of large flow and high pressure can be used as the negative pressure system. In some embodiments, the negative pressure system includes a vacuum pump and a vacuum negative pressure tank.

[0080] In some embodiments, such as Figure 2As shown, the preparation system of the present invention includes a first feeding system 101, a second feeding system 102, a valve microreactor 104, a negative pressure system and an aging device 107. The negative pressure system includes a vacuum negative pressure tank 105 and a vacuum pump 106. The vacuum negative pressure tank 105 is arranged between the valve microreactor 104 and the aging device 107, and is connected to the valve microreactor 104 and the aging device 107 through a pipeline. The first feeding system 101 and the second feeding system 102 are respectively connected to the valve microreactor 104 through a pipeline. The vacuum pump 106 is connected to the vacuum negative pressure tank 105 through a pipeline. The vacuum pump 106 and the vacuum negative pressure tank 105 are used in combination to ensure that a certain negative pressure or normal pressure can always be stably maintained in the vacuum negative pressure tank 105. The negative pressure value in the vacuum negative pressure tank 105 can be adjusted according to the flow rate, concentration of the reactants in the front-end valve type microreactor 104 and the flow rate and concentration, viscosity and solid content of the reaction product, so as to ensure that the reaction product in the valve type microreactor 104 can be removed in time under the action of the feed pressure and the rear-end negative pressure, and ensure that the valve type microreactor 104 can run smoothly without clogging under the reaction conditions of large flow and high pressure. The negative pressure system can be adjusted accordingly depending on the specific reaction situation. The aging device 107 is an aging kettle. The aging kettle is used to age the product under conditions such as stirring at a certain speed and heat preservation.

[0081] In some embodiments, the feed system includes a feeder, a mass flowmeter, a pressure controller and a reversing valve. The reversing valve includes an inlet and at least two outlets. The feed system includes an inlet pipeline connected to the inlet of the reversing valve, a first outlet pipeline connected to the first outlet of the reversing valve, and a second outlet pipeline connected to the second outlet of the reversing valve, the feeder, the mass flowmeter and the pressure controller are arranged on the inlet pipeline, and the reversing valve communicates the inlet pipeline and the first outlet pipeline when the flow detected by the mass flowmeter and the pressure detected by the pressure controller meet the set value. The feeder can be a delivery pump, such as a gear pump, a diaphragm pump or a peristaltic pump. The first outlet pipeline can be connected to the valve microreactor. The second outlet pipeline can be connected to a raw material tank or a washing water tank.

[0082] In some embodiments, such as Figure 3As shown, the preparation system of the present invention includes a first feeding system 101, a second feeding system 102, a valve microreactor 104, a vacuum negative pressure tank 105, a vacuum pump 106, an aging device 107, a first raw material tank 108, a first washing water tank 109, a second raw material tank 110 and a second washing water tank 111. Wherein, the first feeding system 101 includes a first feeding device 301, a first mass flowmeter 302, a first pressure controller 303 and a first reversing valve 304, and the second feeding system 102 includes a second feeding device 401, a second mass flowmeter 402, a second pressure controller 403 and a second reversing valve 404. The reversing valve has a feed port, a discharge port, a raw material reflow port and a washing water reflow port. The feed port of the reversing valve is connected to a feed pipe. The raw material tank and the washing water tank are connected to the feed pipe. The feeding device, the mass flowmeter and the pressure controller are arranged on the feed pipe. The discharge port of the reversing valve is connected to the valve microreactor 104 through a pipeline. The raw material reflux port of the reversing valve is connected to the raw material tank through a pipeline. The washing water reflux port of the reversing valve is connected to the washing water tank through a pipeline. The feeding device is a gear pump. The main function of the gear pump is to deliver liquid raw materials of a specific flow rate and pressure according to the set flow rate. The mass flow meter measures the flow rate in real time and feeds back the flow rate information in time. The pressure control device monitors the liquid pressure in real time and sets the required liquid pressure. When the feeding system is started, before the flow rate and pressure reach the set flow rate and pressure, the reversing valve can be set (for example, controlled by a control system) to allow the raw materials to enter from the feed port and return to the raw material tank from the raw material reflux port to form a cycle to prevent the waste of raw materials. When the flow rate and pressure meet the process requirements, the reversing valve can be set to allow the reaction raw materials to enter the valve microreactor 104 from the discharge port, fully mix and react quickly, and quickly enter the vacuum negative pressure tank 105. After a certain amount is stored, it enters the aging device 107 for a certain period of aging. After the reaction is completed, the washing water in the washing water tank is passed into the feeding system and the valve type microreactor 104 to achieve rapid washing of the feeding system and the valve type microreactor 104. A reversing valve can be arranged between the raw material tank and the washing water tank and the feeding pipeline, and the reversing valve can have a raw material inlet, a washing water inlet and an outlet. The raw material inlet of the reversing valve is connected to the raw material tank through a pipeline, the washing water inlet of the reversing valve is connected to the washing water tank through a pipeline, and the outlet of the reversing valve is connected to the feeding pipeline.

[0083] In some embodiments, the preparation system of the present invention further includes a control system, such as a numerical control system. The control system is used to receive process parameters such as flow rate and pressure measured by detection devices such as flow meters and pressure gauges, and control the operation of working devices such as valves (such as reversing valves), pumps (such as booster pumps, vacuum pumps), and feeding devices according to the received process parameters. The control system can be connected to other systems, devices, equipment, modules, components, etc. in the preparation system of the present invention, such as a feeding system and a valve-type microreactor in a wired or wireless manner.

[0084] The preparation system of the present invention may also include a heating module arranged between one or more feed systems and the valve microreactor. The heating module is used to preheat the material entering the valve microreactor. The heating module can be combined with the valve microreactor, for example, the heating module is arranged before the feed port of the valve microreactor, and the reaction raw materials are heated to the temperature required by the process before entering the valve microreactor. In some embodiments, the preparation system of the present invention includes at least three feed systems and a mixing module arranged between at least two feed systems and the valve microreactor, and the mixing module is used to mix the reaction raw materials from the at least two feed systems and provide the mixed reaction raw materials to the valve microreactor. The mixing module may include a stacked mixer, a valve mixer, a T-type microchannel reactor or a clustered microchannel reactor.

[0085] In some embodiments, such as Figure 4 As shown, the preparation system of the present invention includes a first raw material tank 108, a second raw material tank 110, a third raw material tank 112, a first feeding system 101, a second feeding system 102, a third feeding system 103, a first inlet module 114, a first heating module 115, a second inlet module 116, a third inlet module 117, a mixing module 119, a second heating module 120, a valve microreactor 104, an outlet module 121, an aging device 107 and a negative pressure system ( Figure 6 107 is an aging kettle, and the mixing module 119 is a stacked mixer. The negative pressure system includes a vacuum negative pressure tank and a negative pressure pump, the vacuum negative pressure tank is arranged between the outlet module 121 and the aging device 107, and the negative pressure pump is connected to the vacuum negative pressure tank. In the present invention, the inlet module and the outlet module can be simple inlet and outlet connection modules.

[0086] In some embodiments, such as Figure 5As shown, the valve type microreactor used in the present invention includes a first feed port 201, a second feed port 202, a first feed pressure regulating device 204, a second feed pressure regulating device 203, a reaction chamber 205, a discharge port 206, a micropore 501 and a slit 502. The first feed pressure regulating device 204 is arranged on the flow channel between the first feed port 201 and the reaction chamber 205. The second feed pressure regulating device 203 is arranged on the flow channel between the second feed port 202 and the reaction chamber 205. The reaction chamber 205 is semi-ellipsoidal. The discharge port 206 is flared. The discharge port 206 of the flared trousers is connected to the opening of the semi-ellipsoidal reaction chamber 205, so that the high-concentration reaction product can be quickly discharged, and continuous reaction can be achieved without blockage. Looking at the reaction chamber 205 from the discharge port 206, the cross section of the reaction chamber 205 is elliptical, indicating that the reaction chamber 205 is semi-ellipsoidal. The micropore 501 is disposed at the end of the flow channel between the first feed port 201 and the reaction chamber 205 . The slit 502 is disposed at the end of the flow channel between the second feed port 202 and the reaction chamber 205 .

[0087] A jet-like collision occurs between the various liquids entering the reaction chamber through the various feed ports of the valve-type microreactor. The end of the flow channel between the feed port and the reaction chamber (for example, the end of the flow channel between the first feed port 201 and the reaction chamber 205, the end of the flow channel between the second feed port 202 and the reaction chamber 205) is provided with a plurality of micropores and / or slits distributed in an annular shape. Preferably, the micropores and / or slits are arranged so that the jets ejected from the two flow channel ends correspond to each other one by one, and collide and mix in real time. In some embodiments, such as Figure 5 and Figure 6 As shown, a micropore 501 is provided at the end of the flow channel between the first feed inlet 201 and the reaction chamber 205, and a slit 502 is provided at the end of the flow channel between the second feed inlet 202 and the reaction chamber 205. Preferably, as Figure 6 As shown, the design of micropores 501 and slits 502 allows the jets ejected from the two flow channel ends to correspond to each other and collide and mix in real time. Figure 6 As shown, each micropore 501 is evenly distributed in an annular shape, and each slit 502 is also evenly distributed in an annular shape and corresponds to each micropore 501 one by one, so that the jets sprayed into the reaction chamber 205 from the two flow channel ends can correspond to each other one by one and collide and mix in real time. Preferably, the end of the flow channel between the first feed port 201 and the reaction chamber 205 and the end of the flow channel between the second feed port 202 and the reaction chamber 205 are arranged so that the materials sprayed from the two flow channel ends collide tangentially in the reaction chamber 205.

[0088] In some embodiments, such as Figure 5 and Figure 6As shown, the diameter of the micropore 501 is 10-100 μm, such as 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and the gap of the slit 502 is 100-200 μm, such as 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm. The above-mentioned size design of the micropore and the slit is conducive to the high-speed injection of the material flow, realizing real-time collision mixing and quickly completing the reaction. In this article, the gap of the slit refers to the gap width of the slit.

[0089] In the present invention, Figure 5 As shown, the reaction chamber 205 is preferably semi-ellipsoidal, and the discharge port 206 is preferably bell-bottomed. The bell-bottomed discharge port 206 is connected to the opening of the semi-ellipsoidal reaction chamber 205, so that high-concentration reaction products can be quickly discharged, and continuous reaction can be achieved without blockage.

[0090] The preparation system of the present invention may optionally further include one or more or all of the following equipment or devices: a centrifugal device, a washing device, a filtering device, a drying device, a mixing device, a screening device, a demagnetizing device, and a packaging device. The centrifugal device is used to centrifugally dry the aged positive electrode material precursor slurry. The centrifugal device can be a centrifuge. The washing device is used to perform alkali washing, water washing and other washing operations on the positive electrode material precursor after centrifugal drying. After washing, the filter device is used for filtering. The filter cake is dried into powder particles by a drying device. The drying device can be a dynamic drying device. The dried powder particles enter the mixing device in batches for uniform mixing. The mixing device can be a mixer. The mixed powder is passed through a screening device, such as a screen, to remove large particles that are bonded, and then the magnetic substances in the powder particles are removed by a demagnetizing device, such as a demagnetizer, and finally packaged and packaged into a positive electrode material precursor product by a packaging device, such as a vacuum packaging machine.

[0091] The M ternary positive electrode material precursor of the present invention can be prepared using the preparation system of the present invention. The preparation method can completely avoid the amplification effect, shorten the time from research and development to production of the positive electrode material precursor, and can achieve precise control, and can produce products with stable quality and good consistency. The preparation method of the present invention has a simple start-stop reaction, and the production process greatly reduces the generation of waste and energy consumption compared to traditional production processes.

[0092] In some embodiments, the method for preparing M ternary cathode material precursor includes: providing at least two reaction raw materials to a valve microreactor through a feeding system, allowing each reaction raw material to undergo a co-precipitation reaction in the valve microreactor after passing through a feeding pressure regulating device.

[0093] In some embodiments, the present invention uses Figure 3The preparation system shown prepares M ternary positive electrode material precursor. The salt solution of nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum is configured according to the process requirements, stored in the first raw material tank 108 and kept warm, and the precipitant (such as sodium hydroxide) and the complexing agent (such as ammonia water) are stirred and mixed uniformly in the second raw material tank 110 according to the proportion and concentration required by the process, and stored warm. Then the feeding devices 301 and 401 are started. Before the flow rate and pressure reach the set flow rate and pressure, valves 304 and 404 can be set to allow the raw materials to enter the feed port of the valve and return to the first raw material tank 108 and the second raw material tank 110 from the reflux port to form a cycle, and the waste of raw materials is eliminated. When the flow rate and pressure meet the process requirements, the reaction raw materials can be switched according to the process. Pipeline 104, fully mixed and quickly reacted to generate M ternary positive electrode material precursor, and then quickly enter the vacuum negative pressure tank 105, after a certain amount of storage, it is placed in the aging device 107 for a certain period of aging. After the reaction is completed, the washing water in the first washing water tank 109 and the second washing water tank 111 is quickly introduced into the first feeding system 101, the second feeding system 102 and the valve microreactor 104 to achieve rapid washing. In the present invention, the flow rate setting value of the feed liquid can be 6-720L / h, such as 10L / h, 20L / h, 50L / h, 100L / h, 200L / h, 500L / h, and the pressure setting value can be 3-30bar, such as 5±0.5bar, 8±0.5bar, 10±0.5bar, 15±0.5bar, 20±0.5bar, 25±0.5bar.

[0094] In some embodiments, the present invention uses Figure 4The preparation system shown prepares M ternary positive electrode material precursor. First, nickel salt, cobalt salt and aluminum salt, or nickel salt, cobalt salt and manganese salt are dissolved into a mixed salt solution of a certain concentration and molar ratio according to the process requirements, and stored in the first raw material tank 108, wherein the total concentration of metal elements can be 0.5-2.2mol / L, for example, 0.8mol / L, 1mol / L, 1.2mol / L, 1.5mol / L, 1.8mol / L, 2mol / L, and the higher the concentration, the greater the production capacity in the corresponding time. In the present invention, when the salt solution contains multiple metal elements, the concentration of metal elements in the salt solution refers to the total concentration of all metal elements. For example, for a mixed salt solution of nickel salt, cobalt salt and manganese salt, the concentration of metal elements refers to the total concentration of nickel, cobalt and manganese. The precipitant and the complexing agent are stored in the second raw material tank 110 and the third raw material tank 112, respectively. The concentration of the precipitant (such as sodium hydroxide solution) can be configured to 2-10mol / L according to the specific process requirements, such as 3mol / L, 4mol / L, 5mol / L, 6mol / L, 7mol / L, 8mol / L, 9mol / L. The concentration of the complexing agent (such as ammonia water) can be 2-10mol / L, such as 3mol / L, 4mol / L, 5mol / L, 6mol / L, 7mol / L, 8mol / L, 9mol / L. The higher the concentration, the greater the product capacity at the corresponding time, and the higher the solid content. The precipitant (such as sodium hydroxide solution) and the complexing agent (such as ammonia water) can be stored in the same raw material tank, but it is more conducive to adjusting the pH of the reaction system to store and feed the precipitant and the complexing agent separately. Then, the first feeding system 101 injects the salt solution into the first heating module 115 through the first inlet module 114 according to the process setting flow rate (the production flow rate can be 6-720L / h), and heats it to a certain temperature, generally 30-65°C, through the heating module. The second feeding system 102 and the third feeding system 103 respectively inject the precipitant and the complexing agent into the mixing module 119 (for example, a stacked mixer) according to the process required flow rate (the production flow rate can be 6-720L / h) through the second inlet module 116 and the third inlet module 117 to fully mix the multiple strands of materials, and quickly heat the raw material liquid in the channel to the temperature required by the process, generally 30-65°C, through the second heating module 120, and then directly pass into the valve microreactor 104. The feed pressure can be 3-30bar, for example, 5±0.5bar, 8±0.5bar, 10±0.5bar, 15±0.5bar, 20±0.5bar, 25±0.5bar. Each heating module is combined with the valve microreactor 104, and the heating module is arranged before the feed port of the valve microreactor to heat the corresponding reaction raw materials to the temperature required by the process before entering the valve microreactor. The salt solution is introduced into the valve microreactor 104 to be fully mixed and reacted with the remaining reaction raw materials entering the valve microreactor 104 from another feed port to generate M ternary positive electrode material precursor.In the real-time reaction process of preparing the M ternary cathode material precursor, the molar ratio of ammonia to metal elements in the reaction system in any instantaneous mixed reaction stage is a fixed value, which is between 0-1. For different series of products, the optimal value interval of the ratio of ammonia to metal elements is different; the molar ratio of sodium hydroxide to metal elements is between 2.2:1 and 1.8:1, ensuring that the pH value is stable during instantaneous reaction, and for different series of products, the optimal value is different, and the optimal value range is between 10-12.5. The preparation method of the present invention makes full use of the efficient mass transfer, heat transfer and mixing performance of the valve microreactor, and quickly mixes the materials evenly in a short time to make it react quickly. The final product flows out to the subsequent aging device 107 (such as aging kettle) via the outlet module 121. After a period of aging, the slurry is pumped into a centrifuge for centrifugal drying, alkali washing, water washing and other washing operations to reduce the content of impurities such as ammonia nitrogen, sodium, and sulfate in the product. The filter cake is then dried continuously and regularly at a fixed process temperature by a dynamic drying device into loose powder particles, which are then fed into a mixer in batches for uniform mixing, and then passed through a screen to remove large particles that are bonded, and then passed through a demagnetizer to remove magnetic substances from the powder particles, and finally packaged and packaged into a qualified positive electrode material precursor by a vacuum packaging machine. In some embodiments, a negative pressure system is provided before aging, and the product first enters a vacuum negative pressure tank and then enters an aging device.

[0095] The M ternary positive electrode material precursor has the advantages of stable quality and good consistency. The M ternary positive electrode material precursor is a secondary particle composed of primary particles of nanometer scale (≤100nm). The particle size of the primary particles of the M ternary positive electrode material precursor is between 10nm-100nm, for example, 20nm, 25nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, and the preferred particle size is between 30nm-100nm. In the present invention, the particle size of the primary particles of the M ternary positive electrode material precursor is nanometer scale (≤100nm), while the particle size of the primary particles of the conventional ternary positive electrode material precursor is subnanometer scale to micrometer scale (hundreds of nanometers to several microns). The particle size D50 of the secondary particles of the M ternary positive electrode material precursor can be between 1 μm and 20 μm, such as 2 μm, 3 μm, 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, 18 μm, preferably between 1 μm and 3 μm. The specific surface area of ​​the M ternary positive electrode material precursor is 35-150 m 2 / g, preferably 50-110m 2 / g, for example 60m 2 / g, 70m 2 / g, 80m 2 / g, 90m 2 / g、100m 2 / g, which is 7-10 times that of conventional ternary cathode material precursors (the specific surface area of ​​conventional ternary cathode material precursors is generally 5-15m 2 / g). The shape of the secondary particles of the M ternary cathode material precursor is an irregular shape formed by loosely overlapping primary particles. Herein, the irregular shape includes but is not limited to rod-shaped, disc-shaped, arch-shaped, star-shaped, elliptical, polygonal or any other irregular shape and a mixture of these shapes.

[0096] In the present invention, after the reaction liquid containing the ternary cathode material precursor is prepared by using a microchannel reactor, the reaction liquid is sent to an aging device for aging. The aging device can be an aging kettle. The main purpose of aging is to promote the growth of crystal nuclei and improve the uniformity of primary particle agglomerates. Aging is to allow the reaction liquid to continue to react for a period of time. The aging time can be 2-12h, for example, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h. During aging, the temperature of the reaction liquid is preferably controlled to be 25-80°C, preferably 30-65°C, for example 55-65°C, 60±2°C, 60±1°C, 60±0.5°C. The aged ternary cathode material precursor is washed, dried, and crushed to obtain a ternary cathode material precursor that can be used to prepare a ternary cathode material.

[0097] In the present invention, in step (1), the doping element may be selected from one or more of Zr, Ti, Al, Y, B, W, Mg, Mo and Nb. The compound containing the doping element may be selected from one or more of the oxides and hydroxides of the doping element. In some embodiments, the doping element is Zr, and the compound containing the doping element may be zirconium oxide. The doping element may also be added during the preparation of the ternary cathode material precursor.

[0098] In step (1), the mass of each compound containing the doping element can be 0.1-1wt% of the mass of the ternary positive electrode material precursor, for example, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%.

[0099] The primary calcination in step (2) can be carried out in an oxygen atmosphere or a mixed atmosphere of oxygen and air. When a mixed atmosphere of oxygen and air is used, the volume fraction of oxygen in the mixed atmosphere is preferably ≥ 70%.

[0100] In step (2), the constant temperature (i.e., calcination temperature) during the primary calcination is preferably 700-1000°C, such as 800°C, 850°C, 900°C, 920°C, 950°C. The constant temperature time (i.e., calcination time) during the primary calcination is preferably 4-12h, such as 6h, 8h, 10h. The heating rate during the primary calcination is preferably 0.5°C / min to 4°C / min, such as 1°C / min, 2°C / min, 3°C / min. In a preferred embodiment, a heat preservation platform is set in the temperature rising section of the primary calcination, the heat preservation temperature is 450-850°C, and the heat preservation time is 4-8h.

[0101] In step (3), the bulk material may be roughly broken before crushing.

[0102] In step (4), the coating element may be selected from one or more of Al, Zr, Ti, W, Nb, B, Ce and Mo. The compound containing the coating element may be selected from one or more of the oxides and hydroxides of the coating element. In some embodiments, the coating element is W and Al, and the compound containing the coating element may be tungsten oxide (WO3) and γ-type aluminum hydroxide.

[0103] In step (4), the compound containing the coating element can be coated on the surface of the doped ternary positive electrode material by dry coating or wet coating.

[0104] In step (4), the mass of each compound containing the coating element can be 500 to 5000 ppm of the mass of the doped ternary positive electrode material, for example, 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm.

[0105] In step (4), the constant temperature of the secondary calcination is preferably 250-600° C., such as 300° C., 400° C., 425° C., 450° C., 500° C. The constant temperature time of the secondary calcination is preferably 4-12 hours, such as 6 hours, 8 hours, 10 hours. After the secondary calcination, the single crystal ternary cathode material can be screened.

[0106] The present invention uses a ternary cathode material precursor prepared by a microchannel reactor, especially a valve microreactor, to prepare a small-particle single-crystal ternary cathode material. The key point of the small-particle cathode material is the special preparation process of the precursor, and the subsequent doping and coating methods are all based on the precursor to further exert its performance characteristics. If the precursor prepared by a conventional autoclave reactor is used, and the doping and coating process similar to the present invention is also used, the small-particle single-crystal ternary cathode material of the present invention cannot be obtained. In the present invention, the small particle size refers to the median particle size D50 of the single-crystal ternary cathode material of 1 to 3 μm. The single-crystal cathode material D50 prepared under normal conditions (for example, using a precursor prepared by an autoclave reactor) is 3 to 5 μm. Compared with the precursor prepared by a conventional autoclave reactor, the precursor prepared by a microchannel reactor, especially a valve microreactor, has very different crystal nuclei, morphology, and grain boundary combination forms during the sintering process, which becomes the key to the preparation of the small-particle (D50 is 1 to 3 μm) single-crystal cathode material.

[0107] The single crystal ternary positive electrode material of the present invention has a small particle size, so that the path for lithium ions to escape / embed from the particles is short and the time is short, which can not only improve the specific capacity of the positive electrode material at high voltage, but also effectively improve the material's rate performance and low-temperature capacity retention rate.

[0108] In the present invention, the coating agent coated on the surface of the positive electrode material can prevent the side reaction between the electrolyte and the positive electrode material to a certain extent, improve the cycle performance and safety performance of the positive electrode material, and effectively improve the conductivity of the material interface, further improving the low-temperature capacity retention rate.

[0109] In the present invention, the doping elements improve the internal structure of the crystal, increase the particle consistency of the primary particles, reduce the amount of micropowder on the surface of the matrix, and improve the thermal stability of the material under high temperature conditions.

[0110] The method for preparing the single crystal ternary positive electrode material of the present invention is relatively friendly to industrial production.

[0111] The present invention will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The raw material compounds in the examples can all be purchased through commercial routes.

[0112] Preparation Example 1

[0113] In this preparation example, a valve-type microreactor is used to prepare the M ternary cathode material precursor by the following steps:

[0114] use Figure 4 The preparation system shown in FIG. 1 is used to prepare the M ternary cathode material precursor, wherein the valve microreactor is constructed as shown in FIG. Figure 1 , Figure 5 and Figure 6 As shown, the diameter of the micropore 501 is 50 μm, the gap of the slit 502 is 150 μm, and the structure of the feeding system is as follows Figure 3 As shown, the preparation system includes Figure 4 The negative pressure system shown in the figure includes a vacuum negative pressure tank and a negative pressure pump. The vacuum negative pressure tank is arranged between the outlet module 121 and the aging device 107. The negative pressure pump is connected to the vacuum negative pressure tank. The aging device 107 is an aging kettle.

[0115] A mixed solution of multiple salts of certain concentrations and molar ratios of NiSO4·6H2O, CoSO4·7H2O and MnSO4·H2O is dissolved and stored in a salt storage tank (first raw material tank 108), wherein the total concentration of metal elements is 2 mol / L, and the molar ratio of nickel, cobalt and manganese metal elements is 65:7:28.

[0116] Sodium hydroxide and ammonia water are prepared into sodium hydroxide solution and ammonia water solution of a certain concentration, which are stored in an alkali storage tank (the second raw material tank 110) and an ammonia storage tank (the third raw material tank 112), respectively. The sodium hydroxide concentration c (NaOH) is 8 mol / L, and the ammonia water concentration c (NH3·H2O) is 5 mol / L.

[0117] The second feeding system 102 and the third feeding system 103 feed the ammonia solution and the sodium hydroxide solution at flow rates of 33.6 L / h and 98.4 L / h respectively according to the process requirements and a feed pressure of 8 bar, and then enter the mixing module 119 (stacked mixer) through the second inlet module 116 and the third inlet module 117 to fully mix the two streams of materials. The raw material liquid in the channel is quickly heated to the process required 45°C through the second heating module 120, and then introduced into the valve microreactor 104.

[0118] The first feeding system 101 feeds a metal salt solution with a total concentration of 2 mol / L and a molar ratio of nickel, cobalt, and manganese metal elements of 65:7:28 into the first heating module 115 through the first inlet module 114 according to the process setting flow rate of 168 L / h and a feed pressure of 8 bar. After being heated to 45° C. by the heating module, it is introduced into the valve microreactor 104 and fully mixed with the mixed solution of ammonia solution and sodium hydroxide solution entering the valve microreactor 104 from the other side to generate the ternary positive electrode material precursor Ni 0.65 Co 0.07 Mn 0.28 (OH)2.

[0119] Finally, the product flows out through the outlet module 121, is sucked into the subsequent aging device 107 (aging kettle) through the negative pressure system, and is aged at 60° C. for 2 hours. After washing, drying, and crushing, the M ternary positive electrode material precursor is obtained.

[0120] Example 1

[0121] This embodiment prepares a small-grained single-crystal positive electrode material. The chemical formula of the small-grained single-crystal positive electrode material is LiNi 0.65 Co 0.07 Mn 0.28 O2, the preparation method specifically comprises the following steps:

[0122] (1) Weigh zirconium oxide, lithium hydroxide and the M ternary positive electrode material precursor Ni prepared in Preparation Example 1. 0.65 Co 0.07 Mn 0.28 (OH)2, lithium ions and precursor Ni 0.65 Co 0.07 Mn 0.28 The total molar ratio of nickel, cobalt and manganese ions in (OH)2 is 1.05:1, and the mass of zirconium oxide is 0.3wt% of the mass of the ternary positive electrode material precursor; 0.65 Co 0.07 Mn 0.28 (OH)2, lithium hydroxide and zirconium oxide were added into a high-speed mixer and mixed for 25 minutes to obtain a mixture;

[0123] (2) the mixed material obtained in step (1) is placed in a sagger, and placed in a box furnace, and heated to 920° C. at a heating rate of 1° C. / min in an oxygen atmosphere for calcination for 12 hours to obtain a block material;

[0124] (3) The bulk material obtained in step (2) is coarsely broken and crushed to obtain Zr-doped LiNi 0.65 Co 0.07 Mn 0.28 O2 matrix;

[0125] (4) After the matrix in step (3) is evenly mixed with γ-type aluminum hydroxide and tungsten oxide, the mixture is placed in a crucible, placed in a box furnace and heated to 425° C. for secondary calcination, calcined for 10 hours, and sieved to obtain a single crystal ternary positive electrode material product, wherein the mass of aluminum hydroxide is Zr-doped LiNi 0.65 Co 0.07 Mn 0.28 The mass of O2 matrix is ​​2000ppm, and the mass of tungsten oxide is Zr-doped LiNi 0.65 Co 0.07 Mn 0.282000ppm of O2 matrix mass.

[0126] The SEM image of the single crystal ternary cathode material finally obtained in Example 1 is as follows: Figure 7 shown.

[0127] Example 2

[0128] Example 2 is a method for preparing a small-particle single-crystal positive electrode material. The difference between Example 2 and Example 1 is that the lithium ions and the precursor Ni 0.65 Co 0.07 Mn 0.28 The molar ratio of the sum of nickel, cobalt and manganese ions in (OH)2 is 1.03.

[0129] Example 3

[0130] Example 3 prepares a small-particle single-crystal positive electrode material. The only difference between Example 3 and Example 1 is that the primary calcination time is 10 hours.

[0131] Example 4

[0132] Example 4 prepares a small-particle single-crystal positive electrode material. The only difference between Example 4 and Example 1 is that the primary calcination temperature is 925°C.

[0133] Example 5

[0134] Example 5 A small-particle single-crystal positive electrode material is prepared. The difference between Example 5 and Example 1 is that the mass of aluminum hydroxide is Zr-doped LiNi 0.65 Co 0.07 Mn 0.28 1000ppm of O2 matrix mass.

[0135] Comparative Example 1

[0136] Comparative Example 1: A ternary positive electrode material is prepared according to the process of Example 1. The difference between Comparative Example 1 and Example 1 is that: Comparative Example 1 uses a ternary positive electrode material precursor Ni 0.65 Co 0.07 Mn 0.28(OH)2 was prepared by using an autoclave reactor, and the primary calcination temperature was 965°C. Specifically, the preparation process of the ternary positive electrode material precursor used in Comparative Example 1 is as follows: NiSO4·6H2O, CoSO4·7H2O and MnSO4·H2O are dissolved in deionized water according to a molar ratio of nickel, cobalt and manganese of 65:7:28 to obtain a salt solution with a total metal element concentration of 2 mol / L, the salt solution is mixed with ammonia water with a concentration of 5 mol / L according to a volume ratio of 5:1, a sodium hydroxide solution with a concentration of 8 mol / L is added to adjust the pH to 11, and the reaction is carried out at a constant temperature of 70°C in an autoclave reactor for 8 hours. After the reaction is completed, it is filtered and dried to obtain a ternary positive electrode material precursor Ni 0.65 Co 0.07 Mn 0.28 (OH)2.

[0137] The SEM image of the ternary positive electrode material finally prepared in Comparative Example 1 is as follows Figure 8 shown.

[0138] Comparative Example 2

[0139] Comparative Example 2 uses the ternary cathode material precursor Ni prepared by the kettle reactor 0.65 Co 0.07 Mn 0.28 (OH)2 is used to prepare a ternary positive electrode material whose average primary particle size is equivalent to that of Example 1. The specific preparation process of Example 2 is different from that of Example 1 only in that the ternary positive electrode material precursor used in Comparative Example 2 is the same as that used in Comparative Example 1; the remaining process parameters of Comparative Example 2 are consistent with those of Example 1.

[0140] The SEM image of the ternary positive electrode material finally obtained in Comparative Example 2 is as follows Fig. 9 As shown. Fig. 9 It can be seen that when using a conventional precursor prepared by a kettle reactor, if one wants to prepare a single-crystal ternary positive electrode material with a D50 of 1 to 3 μm (i.e., the primary particle size is equivalent to that of the present invention), single-crystal-like agglomerates will usually appear, and the primary particle dispersion is extremely poor. The cycle retention rate and gas production performance under high voltage are far inferior to those in Example 1.

[0141] Comparative Example 3

[0142] Comparative Example 3: A ternary positive electrode material is prepared according to the process of Example 1. The only difference between Comparative Example 3 and Example 1 is that no coating treatment is performed after the first calcination.

[0143] The SEM image of the ternary positive electrode material finally obtained in Comparative Example 3 is as follows Fig.10 As shown. Fig.10It can be seen that the morphology of the uncoated single crystal ternary positive electrode material is not significantly different from that of Example 1, that is, the material morphology has been finalized in the first calcination process.

[0144] Test Example 1: Particle Size Distribution and Primary Particle Size

[0145] The particle sizes D10, D50 and D90 of the ternary positive electrode material precursors of Examples 1-5 and Comparative Examples 1-3 were measured using a Malvern laser particle size analyzer. The average particle size of the primary particles and the percentage of primary particles with a particle size greater than 3 μm of the ternary positive electrode material precursors of Examples 1-5 and Comparative Examples 1-3 were measured using SEM. The results are shown in Table 1.

[0146] Test Example 2: Normal temperature discharge capacity, low temperature capacity retention rate and high temperature cycle capacity retention rate

[0147] The ternary cathode materials of Examples 1-5 and Comparative Examples 1-3 were prepared into lithium-ion batteries using the following method:

[0148] (1) mixing a ternary positive electrode material, conductive carbon black, and PVDF in a mass ratio of 96:2:2, and then adding N-methylpyrrolidone (NMP) to knead, high-speed disperse, and adjust the viscosity to prepare a positive electrode slurry;

[0149] (2) Graphite, conductive carbon black, and sodium carboxymethyl cellulose (CMC) are mixed in a mass ratio of 96.7:1:1.5, and then water is added for kneading, high-speed dispersion, and viscosity adjustment. Finally, styrene-butadiene rubber (SBR) accounting for 0.8% of the total mass of the solid components of the negative electrode slurry is added for dispersion to prepare a negative electrode slurry;

[0150] (3) Aluminum foil is used as the positive electrode current collector, and copper foil is used as the negative electrode current collector. The positive and negative electrode slurries are coated on the positive electrode current collector and the negative electrode current collector respectively. After rolling, die cutting and baking, the positive electrode sheets and the negative electrode sheets are obtained. The positive and negative electrode sheets are stacked, assembled, injected, allowed to stand, aged and divided to make a 5Ah soft-pack battery. The electrolyte formula is as follows: the solvent is ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a mass ratio of 2:5:3, the lithium salt is LiPF6, and the lithium salt concentration in the electrolyte is 1.1 mol / L.

[0151] The room temperature discharge specific capacity, low temperature capacity retention rate and high temperature cycle capacity retention rate of the lithium ion batteries corresponding to the ternary positive electrode materials of Examples 1-5 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0152] The discharge capacity at room temperature is 25℃, 2.8~4.35V, 0.1C constant current and constant voltage charging, and 0.1C discharge step. The discharge capacity at low temperature is -25℃, 2.8~4.35V, 0.1C constant current and constant voltage charging, and 0.1C discharge step. Low temperature capacity retention rate = low temperature discharge capacity / normal temperature discharge capacity. The high temperature cycle capacity retention rate is 45℃, 2.8~4.35V, 1C constant current and constant voltage charging, 1C discharge step, 50-week discharge capacity retention rate.

[0153] Table 1: Particle size distribution, primary particle size and corresponding lithium-ion battery performance of ternary positive electrode materials of Examples 1-5 and Comparative Examples 1-3

[0154]

[0155] It can be seen from Table 1 that the primary particle size of the ternary positive electrode material prepared by the positive electrode material precursor prepared in the autoclave reactor in Comparative Example 1 is significantly larger than that in Example 1, and the corresponding low-temperature capacity retention rate of the lithium-ion battery is lower than that in Example.

[0156] Comparative Example 2 uses a tank reactor to prepare a cathode material precursor, and its primary particle size is consistent with that of Example 1. However, since its particle morphology is mostly polycrystalline or quasi-single crystal, its dispersibility is poor, and the cathode material in the cathode sheet prepared by it has poor wettability with the electrolyte, and the lithium ion deintercalation path is longer than that of Example 1, so the low-temperature capacity retention rate is also lower than that of Example 1. At the same time, Comparative Example 2 is a polycrystalline / quasi-single crystal material, which loses the basic performance characteristics of high-voltage and high-temperature resistance of single-crystal ternary cathode materials, and its high-temperature cycle retention rate is significantly lower.

[0157] Comparative Example 3 synthesizes a primary particle morphology similar to that of Example 1 based on the M ternary positive electrode material precursor. However, due to the lack of coating treatment, its low-temperature capacity retention rate and high-temperature cycle capacity retention rate are not as good as those of Example 1.

[0158] It can be seen that the key points of the small-particle single-crystal ternary positive electrode material of the present invention lie in the precursor and the primary calcination process, but the subsequent coating and secondary calcination are also the key to further exerting its performance.

Claims

1. A method for preparing a single crystal ternary cathode material, characterized in that: The method comprises the following steps: (1) uniformly mixing a lithium source, one or more compounds containing doping elements, and a ternary cathode material precursor prepared using a microchannel reactor to obtain a mixed material; (2) calcining the mixed material obtained in step (1) in an oxygen-containing atmosphere to obtain a bulk material; (3) crushing the bulk material obtained in step (2) to obtain a doped ternary positive electrode material matrix; (4) The doped ternary cathode material matrix obtained in step (3) and one or more compounds containing coating elements are uniformly mixed and subjected to secondary calcination to obtain the single crystal ternary cathode material.

2. The method according to claim 1, characterized in that Step (1) has one or more of the following characteristics: The ratio of the amount of lithium element in the lithium source to the amount of the ternary cathode material precursor is (1-1.1):1, preferably (1.02-1.06):1; The lithium source is selected from one or more of lithium hydroxide, lithium carbonate, lithium nitrate and lithium acetate, preferably lithium hydroxide; The chemical formula of the ternary cathode material precursor is Ni x Co y M z (OH)2 or Ni x Co y M z O m H n , wherein M is Al or Mn, 0.3≤x≤0.7, 0.05≤y≤0.3, 0.05≤z≤0.4, x+y+z=1, m>0, n>0, 2m-n=2; preferably, 0.6≤x≤0.7, 0.05≤y≤0.1, 0.2≤z≤0.3; The doping element is selected from one or more of Zr, Ti, Al, Y, B, W, Mg, Mo and Nb, preferably Zr; The compound containing the doping element is selected from one or more of oxides and hydroxides of the doping element; The weight of each compound containing doping elements is 0.1-1 wt % of the weight of the ternary positive electrode material precursor.

3. The method according to claim 1, characterized in that In step (1), the ternary cathode material precursor is generated by coprecipitation reaction of nickel salt, cobalt salt and aluminum salt or nickel salt, cobalt salt and manganese salt in the presence of a precipitant and a complexing agent in a microchannel reactor.

4. The method according to claim 3, characterized in that The microchannel reactor is a valve-type microreactor, which includes a first feed port, a second feed port, a first feed pressure regulating device, a second feed pressure regulating device, a reaction chamber and a discharge port. The first feed port is connected to the reaction chamber through a first flow channel, and the second feed port is connected to the reaction chamber through a second flow channel. The first feed pressure regulating device is arranged on the first flow channel between the first feed port and the reaction chamber, and is used to control the feed pressure of the first feed port. The second feed pressure regulating device is arranged on the second flow channel between the second feed port and the reaction chamber, and is used to control the feed pressure of the second feed port. The discharge port is connected to the reaction chamber, and the nickel salt, cobalt salt and aluminum salt or the nickel salt, cobalt salt and manganese salt are fed to the reaction chamber through the first flow channel, and the precipitant and complexing agent are fed to the reaction chamber through the second flow channel.

5. The method according to claim 4, characterized in that The ends of the first flow channel and the second flow channel are provided with a plurality of micro-holes and / or slits distributed in an annular shape, so that the jets ejected from the ends of the first flow channel and the second flow channel correspond to each other one by one, and real-time collision and mixing occur.

6. The method according to claim 1, characterized in that Step (2) has one or more of the following characteristics: The primary calcination is carried out in an oxygen atmosphere or a mixed atmosphere of oxygen and air; The constant temperature of the primary calcination is 700-1000°C; The constant temperature time for a calcination is 4 to 12 hours; The heating rate of the primary calcination is 0.5°C / min to 4°C / min.

7. The method according to claim 1, characterized in that Step (4) has one or more of the following characteristics: The coating element is selected from one or more of Al, Zr, Ti, W, Nb, B, Ce and Mo, preferably W and Al; The compound containing the coating element is one or more selected from oxides and hydroxides of the coating element; The mass of each compound containing the coating element is 500 to 5000 ppm of the mass of the doped ternary positive electrode material; The constant temperature of the secondary calcination is 250-600°C; The constant temperature time of the secondary calcination is 4 to 12 hours.

8. A single crystal ternary positive electrode material prepared by the method according to any one of claims 1 to 7.

9. The single crystal ternary cathode material according to claim 8, characterized in that: The average particle size of primary particles of the single crystal ternary positive electrode material is 0.8-1.8 μm; and / or, in the single crystal ternary positive electrode material, the percentage of primary particles with a particle size greater than 3 μm in the total number of primary particles is ≤5%.

10. The single crystal ternary cathode material according to claim 8, characterized in that: The particle size D50 of the single crystal ternary positive electrode material is 1 to 3 μm; and / or the particle size D90 of the single crystal ternary positive electrode material is 3 to 6.5 μm.

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