Medium-high nickel single crystal ternary positive electrode material and preparation method thereof

Abstract

The invention provides a medium-high nickel single crystal ternary positive electrode material and a preparation method thereof, and the method comprises the following steps: (1) uniformly mixing lithium carbonate, 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) the mixed material obtained in the step (1) is subjected to primary calcination in an oxygen-containing atmosphere, a blocky material is obtained, primary calcination comprises two stages of calcination, first-stage calcination is conducted at the temperature of 250-700 DEG C, and then second-stage calcination is conducted at the temperature of 700-1000 DEG C; (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. According to the invention, lithium carbonate is applied to preparation of the medium-high nickel single crystal ternary positive electrode material.

Description

Technical Field

[0001] The present invention belongs to the field of battery materials, and in particular relates to a medium-high nickel single crystal ternary positive electrode material and a preparation method thereof. Background Art

[0002] Compared with lithium hydroxide, lithium carbonate is cheaper. However, since the reaction activity and reaction temperature of lithium carbonate are inferior to lithium hydroxide, when the Ni content in the ternary positive electrode material is high, the primary calcination temperature is 700℃~800℃, which is close to the decomposition temperature of lithium carbonate. This will cause the lithium carbonate to be not completely decomposed during the crystal growth of the medium-high nickel positive electrode material (the primary calcination temperature of the low-nickel material is around 900℃, at which time lithium carbonate can be almost completely decomposed into lithium oxide), which will affect the forward progress of the reaction and the carbon dioxide retained in the solid phase will cause the material crystallization performance to be very poor. Therefore, in commercial production, medium-high nickel ternary positive electrode materials (Ni mol% ≥ 65%) are difficult to be compatible with lithium carbonate, which limits the further reduction of the cost of ternary single crystal positive electrode materials. Existing medium-high nickel single crystal ternary positive electrode materials basically all use lithium hydroxide as the lithium source, which makes the product cost of medium-high nickel single crystal ternary positive electrode materials relatively high. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention finds that the ternary cathode material precursor prepared by a microchannel reactor has special properties, and the compatibility with lithium carbonate is improved in the process of preparing medium-high nickel single crystal ternary cathode materials, so that lithium carbonate has a good application prospect in medium-high nickel single crystal ternary cathode material products. The present invention utilizes the synergistic effect of the ternary cathode material precursor prepared by a microchannel reactor and lithium carbonate to achieve the application of lithium carbonate in medium-high nickel single crystal ternary cathode materials under commercial conditions.

[0004] Specifically, the present invention provides a method for preparing a single crystal ternary cathode material, the method comprising the following steps:

[0005] (1) mixing lithium carbonate, one or more compounds containing doping elements, and a ternary cathode material precursor prepared using a microchannel reactor to obtain a mixed material;

[0006] (2) calcining the mixed material obtained in step (1) in an oxygen-containing atmosphere to obtain a block material, wherein the calcination comprises two stages, a first stage calcination at 250 to 700° C. and a second stage calcination at 700 to 1000° C.;

[0007] (3) crushing the bulk material obtained in step (2) to obtain a doped ternary positive electrode material matrix;

[0008] (4) uniformly mixing the doped ternary cathode material matrix obtained in step (3) and one or more compounds containing coating elements, and performing secondary calcination to obtain the single crystal ternary cathode material;

[0009] The single crystal ternary positive electrode material is a nickel-cobalt-manganese ternary positive electrode material or a nickel-cobalt-aluminum ternary positive electrode material. In the single crystal ternary positive electrode material, the amount of nickel element accounts for more than 65% of the total amount of nickel-cobalt-manganese elements or nickel-cobalt-aluminum elements.

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

[0011] In one or more embodiments, in step (1), 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, 0.65≤x≤0.8, 0.05≤y≤0.2, x+y+z=1, m>0, n>0, 2m-n=2.

[0012] In one or more embodiments, in step (1), the doping element comprises Ce and / or Sr.

[0013] In one or more embodiments, in step (1), the doping element further comprises one or more selected from Zr, Ti, Al, Y, B, W, Mg, Mo and Nb, preferably further comprises Zr.

[0014] In one or more embodiments, in step (1), 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, in step (1), 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, in step (2), the primary calcination is performed in an oxygen atmosphere or a mixed atmosphere of oxygen and air.

[0020] In one or more embodiments, in step (2), in the first calcination, the time of the first calcination is 2 to 8 hours.

[0021] In one or more embodiments, in step (2), in the first calcination, the time of the second calcination is 4 to 12 hours.

[0022] In one or more embodiments, in step (2), the heating rate of the primary calcination is 0.5° C. / min to 4° C. / min.

[0023] In one or more embodiments, in step (2), the bulk material has a honeycomb structure.

[0024] In one or more embodiments, in step (4), the coating element is selected from one or more of Al, Zr, Ti, W, Nb, B, Ce and Mo, preferably Al.

[0025] In one or more embodiments, in step (4), the compound containing the coating element is one or more selected from oxides and hydroxides of the coating element.

[0026] In one or more embodiments, in step (4), the mass of each compound containing the coating element is 500 to 5000 ppm of the mass of the doped ternary positive electrode material.

[0027] In one or more embodiments, in step (4), the temperature of the secondary calcination is 250-600°C.

[0028] In one or more embodiments, in step (4), the secondary calcination time is 4 to 12 hours.

[0029] The present invention also provides a single crystal ternary positive electrode material prepared by the method described in any embodiment of the present invention.

[0030] In one or more embodiments, the average number of micropowders on the surface of primary particles of the single crystal ternary positive electrode material is ≤2. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] 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.

[0033] 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.

[0034] Figure 4 Schematic diagram of a system for preparing a cathode material precursor in some embodiments of the present invention. Figure 4Among 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.

[0035] 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.

[0036] 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.

[0037] Figure 7 This is the side appearance of the material after the first calcination in Example 1 of the present invention.

[0038] Figure 8 This is the front appearance of the material after the first calcination in Example 1 of the present invention.

[0039] Fig. 9 This is a scanning electron microscope (SEM) image of the single crystal ternary positive electrode material prepared in Example 1 of the present invention.

[0040] Fig.10 This is the SEM image of the single crystal ternary positive electrode material prepared in Comparative Example 1 of the present invention.

[0041] Fig.11 This is a SEM image of the single crystal ternary positive electrode material prepared in Comparative Example 2 of the present invention.

[0042] Fig.12 This is the side appearance of the material after the first calcination in Comparative Example 3 of the present invention.

[0043] Fig.13 This is the front appearance of the material after the first calcination in Comparative Example 3 of the present invention.

[0044] Fig.14 This is the SEM image of the single crystal ternary positive electrode material prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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).

[0049] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0050] 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.

[0051] 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.

[0052] The single crystal ternary positive electrode material of the present invention is prepared using a ternary positive electrode material precursor prepared by a microchannel reactor and using lithium carbonate as a lithium source.

[0053] The chemical formula of the single crystal ternary cathode material of the present invention is Li n Ni x Co y M z A mO2, wherein M is Mn or Al, 1≤n≤1.1, x+y+z=1, 0.65≤x<1, 0<y<0.35, 0<z<0.35, and A is a doping element and a coating element. The single crystal ternary positive electrode material of the present invention is a medium-high nickel single crystal ternary positive electrode material. In the present invention, "medium-high nickel" means that the amount of nickel in the ternary positive electrode material accounts for more than 65% of the total amount of nickel-cobalt-manganese or nickel-cobalt-aluminum.

[0054] Preferably, the chemical formula of the single crystal ternary cathode material of the present invention is Li n Ni x Co y M z A m In O2, 0.65≤x<1, for example, x can be 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or within the range of any two of the aforementioned values, and x is preferably 0.65-0.8; 0<y≤0.2, for example, y can be 0.05, 0.07, 0.1, 0.12, 0.15, 0.2 or within the range of any two of the aforementioned values, and y is preferably 0.05-0.2; 0<z≤0.35, for example, 0.05, 0.1, 0.15, 0.2, 0.25, 0.26, 0.28, 0.3 or within the range of any two of the aforementioned values, and z is preferably 0.05-0.3, more preferably 0.15-0.3; n can be 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.08 or within the range of any two of the aforementioned values.

[0055] The single crystal ternary positive electrode material of the present invention has a small amount of micropowder on the surface of the primary particles, which is reflected in that the average number of micropowders on the surface of a single primary particle is ≤2, for example ≤1, ≤0.5, ≤0.4, ≤0.3. In the present invention, "micropowder" refers to fine particles located on the surface of primary particles and having a particle size smaller than that of primary particles. The amount of micropowder on the surface of primary particles can be measured using a scanning electron microscope (SEM). When the amount of micropowder increases, the crystallinity of the grains is poor, and the side reactions with the electrolyte increase, which leads to a significant decrease in the material's cycle retention rate, high temperature storage, gas production and other performances.

[0056] The single crystal ternary cathode material of the present invention is prepared by a method comprising the following steps:

[0057] (1) uniformly mixing a ternary cathode material precursor, lithium carbonate and a compound containing a doping element prepared by using a microchannel reactor to obtain a mixed material;

[0058] (2) calcining the mixed material obtained in step (1) in an oxygen-containing atmosphere to obtain a bulk material;

[0059] (3) crushing the bulk material obtained in step (2) to obtain a crushed material, i.e., a doped ternary positive electrode material matrix;

[0060] (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.

[0061] In the present invention, in step (1), the ratio of the amount of lithium element in lithium carbonate to the amount of substance of the ternary positive electrode material precursor (i.e. the total amount of nickel, cobalt, manganese elements or nickel, cobalt, aluminum elements in the ternary positive electrode material precursor) is (1-1.1):1, preferably (1.02-1.06):1, for example, 1.03:1, 1.04:1, 1.05:1.

[0062] The ternary cathode material precursor used in the present invention is a ternary cathode material precursor prepared by a microchannel reactor.

[0063] 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, 0.65≤x<1, 0<y<0.35, 0<z<0.35, 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.

[0064] 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 0.65≤x<1, for example, x can be 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or in the range of any two of the foregoing values, and x is preferably 0.65-0.8; 0<y≤0.2, for example, y can be 0.05, 0.07, 0.1, 0.12, 0.15, 0.2 or in the range of any two of the foregoing values, and y is preferably 0.05-0.2; 0<z≤0.35, for example, 0.05, 0.1, 0.15, 0.2, 0.25, 0.26, 0.28, 0.3 or in the range of any two of the foregoing values, and z is preferably 0.05-0.3, more preferably 0.15-0.3.

[0065] In some preferred embodiments, the chemical formula of the ternary cathode material precursor is Ni x Co y M z (OH)2, M is Mn or Al, preferably Mn, x is preferably 0.65 to 0.8, y is preferably 0.05 to 0.2, and z is preferably 0.15 to 0.3.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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 .

[0077] 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.

[0078] 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.

[0079] 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.

[0080] The valve type microreactor in the present invention may include a T-type microchannel reactor or a cluster microchannel reactor.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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 .

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] In the present invention, in step (1), the doping element includes one or two selected from Ce and Sr, and optionally may also include one or more selected from Zr, Ti, Al, Y, B, W, Mg, Mo and Nb. The compound containing the doping element may be one or more selected from the oxides and hydroxides of the doping element. In some embodiments, the doping element is Ce and / or Sr, and the compound containing the doping element may be CeO2 and / or SrO. In some embodiments, the doping element is one or two selected from Ce and Sr and Zr, and the compound containing the doping element may be one or two selected from CeO2 and SrO and ZrO2. The doping element may also be added during the preparation of the ternary cathode material precursor.

[0102] 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%.

[0103] 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%.

[0104] In step (2), it is preferred to use a two-stage calcination method for primary calcination, the calcination temperature of the first stage is 250-700°C, such as 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, and the calcination time of the first stage is 2-8h, such as 4h, 5h, 6h, 7h; the calcination temperature of the second stage is 700-1000°C, such as 750°C, 800°C, 850°C, 900°C, 940°C, 945°C, 950°C, and the calcination time of the second stage is 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. Herein, the first stage of the primary calcination is referred to as the insulation stage, and the second stage of the primary calcination is referred to as the constant temperature stage.

[0105] In step (2), the block material obtained by calcining the M ternary positive electrode material precursor once has a honeycomb-like appearance.

[0106] In step (3), the bulk material may be roughly broken before crushing.

[0107] 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 Al, and the compound containing the coating element may be aluminum oxide and / or aluminum hydroxide.

[0108] 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.

[0109] 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, 1500 ppm, 2000 ppm, 3000 ppm, 4000 ppm.

[0110] In step (4), the calcination temperature of the secondary calcination is preferably 250-600° C., such as 300° C., 400° C., 425° C., 450° C., 500° C., 550° C. The calcination 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.

[0111] In the present invention, the material obtained by calcining the M ternary positive electrode material precursor and lithium carbonate once has a honeycomb structure, which can effectively promote the discharge of waste gas and increase the oxygen partial pressure of the product during the sintering process. This becomes one of the key factors for the application of lithium carbonate in medium and high nickel single crystal ternary positive electrode materials, which is rare in the sintering process of the ternary positive electrode material precursor prepared using an autoclave reactor.

[0112] In the present invention, due to the special structure and properties of the M ternary positive electrode material precursor, if a compound containing Ce or Sr is not used as a dopant, a large amount of micropowder is easily generated on the surface of the primary particles after one calcination and the particles are angular. The use of a dopant containing Ce and / or Sr can effectively reduce the amount of micropowder on the surface of the primary particles after one calcination and increase the roundness of the particles.

[0113] In the present invention, the setting of the heat preservation section in the primary calcination is necessary, which can effectively promote the rapid discharge of waste gas along the pores. If the heat preservation section is not set and the waste gas directly enters the constant temperature section, the presence of waste gas will seriously affect the growth of crystals, and the circulation and storage performance of the positive electrode material will be attenuated. The heat preservation section and the honeycomb structure in the primary calcination complement each other and are indispensable. They are the key factors for lithium carbonate to be used in medium and high nickel single crystal ternary positive electrode materials.

[0114] 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.

[0115] Preparation Example 1

[0116] In this preparation example, a valve-type microreactor is used to prepare the M ternary cathode material precursor Ni by the following steps: 0.65 Co 0.07 Mn 0.28 (OH)2:

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] Example 1

[0124] This embodiment prepares a medium-high nickel single crystal ternary positive electrode material. The chemical formula of the single crystal ternary positive electrode material is LiNi 0.65 Co 0.07 Mn 0.28 O2, the preparation method specifically comprises the following steps:

[0125] (1) Weigh zirconium oxide, strontium oxide, lithium carbonate 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 in lithium carbonate 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, the mass of zirconium oxide is 0.2wt% of the mass of the ternary positive electrode material precursor, and the mass of strontium oxide is 0.1wt% of the mass of the ternary positive electrode material precursor; the ternary positive electrode material precursor Ni 0.65 Co 0.07 Mn 0.28 (OH)2, lithium carbonate, zirconium oxide and strontium oxide are added into a high-speed mixer and mixed for 25 minutes to obtain a mixture;

[0126] (2) The mixed material obtained in step (1) is placed in a sagger, placed in a box furnace and calcined once in an oxygen atmosphere, first heated to 500° C. at a heating rate of 1° C. / min and kept at that temperature for 6 h, then heated to 945° C. at a heating rate of 1° C. / min and calcined for 10 h to obtain a honeycomb-shaped block material; the appearance of the material obtained by the primary calcination is as follows: Figure 7 and Figure 8 As shown, it can be seen that the material after the first calcination has a honeycomb structure;

[0127] (3) The bulk material obtained in step (2) is roughly crushed and pulverized to obtain Zr and Sr co-doped LiNi 0.65 Co 0.07 Mn 0.28 O2 matrix;

[0128] (4) After the matrix and aluminum hydroxide in step (3) are mixed evenly, they are placed in a crucible, placed in a box furnace and heated to 400° 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 and Sr co-doped LiNi 0.65 Co 0.07 Mn 0.28 1500ppm of O2 matrix mass.

[0129] The SEM image of the single crystal ternary cathode material finally obtained in Example 1 is as follows: Fig. 9 shown.

[0130] Example 2

[0131] Example 2 prepares a medium-high nickel single crystal ternary positive electrode material. The preparation process of Example 2 differs from that of Example 1 only in that Example 2 uses cerium oxide instead of strontium oxide in step (1), and the mass of cerium oxide is 0.1wt% of the mass of the ternary positive electrode material precursor.

[0132] Comparative Example 1

[0133] Comparative Example 1 prepares a medium-high nickel single crystal ternary positive electrode material. The preparation process of Comparative Example 1 differs from that of Example 1 only in that: No strontium oxide is added in step (1) of Comparative Example 1.

[0134] The SEM image of the single crystal ternary cathode material finally obtained in Comparative Example 1 is as follows: Fig.10 shown.

[0135] Comparative Example 2

[0136] Comparative Example 2 prepares a medium-high nickel single crystal ternary positive electrode material. The preparation process of Comparative Example 2 differs from that of Example 1 only in that the 500° C. insulation stage is omitted in step (2) of Comparative Example 2.

[0137] The SEM image of the single crystal ternary cathode material finally obtained in Comparative Example 2 is as follows: Fig.11 shown.

[0138] Comparative Example 3

[0139] Comparative Example 3 prepares a medium-high nickel single crystal ternary positive electrode material. The preparation process of Comparative Example 3 differs from that of Example 1 only in that: Comparative Example 3 uses a ternary positive electrode material precursor prepared by an autoclave reactor. Specifically, the preparation process of the ternary positive electrode material precursor used in Comparative Example 3 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 elements 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 in 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.

[0140] The appearance of the material obtained by calcining once in Comparative Example 3 is as follows Fig.12 and Fig.13 As shown in FIG. 1 , it can be seen that the material after the first calcination does not have a honeycomb structure. The SEM image of the single crystal ternary positive electrode material finally prepared in Comparative Example 3 is shown in FIG. Fig.14 shown.

[0141] Test Example 1: Average number of micropowders on the surface of a single particle

[0142] The average amount of fine powder on the surface of single particles of the single crystal ternary positive electrode materials of Examples 1-2 and Comparative Examples 1-3 was measured using SEM. The results are shown in Table 1.

[0143] Test Example 2: Normal temperature discharge specific capacity, normal temperature first efficiency and cycle capacity retention rate

[0144] The ternary cathode materials of Examples 1-2 and Comparative Examples 1-3 were prepared into lithium-ion batteries using the following method:

[0145] (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;

[0146] (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;

[0147] (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.

[0148] 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 1-2 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0149] The discharge specific capacity at room temperature is 25°C, 2.8~4.35V, 0.1C constant current and constant voltage charging, and the discharge specific capacity under 0.1C discharge step. The first effect at room temperature is 25°C, 2.8~4.35V, 0.1C constant current and constant voltage charging, and the ratio of the discharge specific capacity to the charging specific capacity under 0.1C discharge step. The cycle capacity retention rate is the 50-week discharge specific capacity retention rate at 25°C, 2.8~4.35V, 1C constant current and constant voltage charging, and 1C discharge step. Table 1: The average number of micropowders on the surface of single particles of the ternary positive electrode materials of Examples 1-2 and Comparative Examples 1-3 and the performance of the corresponding lithium-ion batteries

[0150]

[0151] As can be seen from Table 1, the average amount of micropowder on the primary particle surface of Examples 1 and 2 is less than that of Comparative Examples 1-3, and the performances such as room temperature discharge specific capacity, first efficiency and cycle capacity retention rate are significantly better than those of Comparative Examples 1-3. The amount of micropowder on the primary particle surface of the ternary positive electrode material (Comparative Example 3) prepared by using a precursor prepared in a conventional kettle reactor and lithium carbonate is significantly increased compared with Examples 1 and 2.

Claims

1. A method for preparing a single crystal ternary cathode material, characterized in that: The method comprises the following steps: (1) mixing lithium carbonate, 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 block material, wherein the calcination comprises two stages, a first stage calcination at 250 to 700° C. and a second stage calcination at 700 to 1000° C.; (3) crushing the bulk material obtained in step (2) to obtain a doped ternary positive electrode material matrix; (4) uniformly mixing the doped ternary cathode material matrix obtained in step (3) and one or more compounds containing coating elements, and performing secondary calcination to obtain the single crystal ternary cathode material; The single crystal ternary positive electrode material is a nickel-cobalt-manganese ternary positive electrode material or a nickel-cobalt-aluminum ternary positive electrode material. In the single crystal ternary positive electrode material, the amount of nickel element accounts for more than 65% of the total amount of nickel-cobalt-manganese elements or nickel-cobalt-aluminum elements.

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 lithium carbonate to the amount of the ternary cathode material precursor is (1-1.1):1, preferably (1.02-1.06):1; 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, 0.65≤x≤0.8, 0.05≤y≤0.2, x+y+z=1, m>0, n>0, 2m-n=2; The doping element comprises Ce and / or Sr; preferably, the doping element further comprises one or more selected from Zr, Ti, Al, Y, B, W, Mg, Mo and Nb; more preferably, the doping element further comprises 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 micropores 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; In a calcination, the first calcination time is 2 to 8 hours; In the first calcination, the second calcination time 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 In step (2), the block material has a honeycomb structure.

8. 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 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 temperature of the secondary calcination is 250-600°C; The secondary calcination time is 4 to 12 hours.

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

10. The single crystal ternary cathode material according to claim 9, characterized in that: The average number of micropowders on the surface of primary particles of the single crystal ternary positive electrode material is ≤2.

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