Primary particle morphology-adjustable high-nickel positive electrode material precursor and preparation method and application thereof

Abstract

The invention provides a high-nickel positive electrode material precursor with an adjustable primary particle morphology and a preparation method and application of the high-nickel positive electrode material precursor with the adjustable primary particle morphology. The primary particle morphology-adjustable high-nickel positive electrode material precursor with specific primary particle size and included angle distribution is prepared, and the positive electrode material obtained through the precursor has excellent high-voltage electrochemical performance; moreover, the preparation method disclosed by the invention is simple in process and low in manufacturing cost, and the obtained positive electrode material is excellent in performance and convenient for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a primary particle morphology-adjustable high-nickel positive electrode material precursor and a preparation method and application thereof. Background Art

[0002] The capacity of lithium-ion batteries is closely related to the performance of positive electrode materials. At present, in order to improve the capacity of positive electrode materials, methods such as increasing the Ni content of positive electrode materials and increasing the cutoff voltage of positive electrode materials are usually adopted, but these methods currently face the problem of unstable positive electrode material structure. On the one hand, with the increase of nickel content, high nickel positive electrode will have problems such as cation mixing, intracrystalline / intercrystalline cracks, structural degradation and interface side reactions, causing the battery performance to decline rapidly; on the other hand, with the increase of cutoff voltage, the particle cracks, interface side reactions and structural degradation problems of positive electrode materials will also become very prominent. At higher cutoff voltages, more severe anisotropic strain will occur inside the positive electrode material, eventually causing serious particle fracture. Therefore, it is very necessary to find a way to improve the structural stability of high nickel positive electrode materials under high voltage conditions.

[0003] At present, the main methods for improving the stability of high-nickel positive electrode materials under high voltage include element doping, element coating and core-shell structure design. For example, CN114094060A discloses a method for preparing a high-voltage positive electrode material with a core-shell structure, comprising the following steps: (1) ultrasonically dispersing a nickel source, a manganese source and a lithium source in an organic solvent, stirring and dissolving to form a nickel-manganese-lithium solution; (2) ultrasonically dispersing a ternary positive electrode material in an organic solvent, and then gradually adding the nickel-manganese-lithium solution to the ternary positive electrode material solution, stirring and drying the solution to obtain a powder precursor; (3) drying the powder precursor, heating and sintering it in an oxidizing atmosphere, and then cooling it to obtain a sintered material; (4) electro-activating the sintered material to obtain a high-voltage positive electrode material with a core-shell structure. The invention has a complex preparation process, high production cost, and it is difficult to ensure the uniformity of the coating layer, making it difficult to mass produce. CN114256456A discloses a high-voltage positive electrode material and a battery containing the positive electrode material. In the patent, the positive electrode material is adjusted by regulating the type of doping elements, the doping amount of doping elements, and the position of doping elements to give full play to the advantages of different doping elements, so that the comprehensive performance of the positive electrode material is greatly improved. Among them, the metal element Al, the metal element Me and the element M are doped in the cobalt position of lithium cobalt oxide to maintain the stability of the positive electrode material structure and improve the capacity of the positive electrode material; the element B is surface modified and / or doped in different positions in lithium cobalt oxide to improve the cycle stability and first coulomb efficiency of the positive electrode material. The patent has a complex reaction process, too many types of doping elements, and high material costs, making it difficult to commercialize.

[0004] High nickel cathode material precursors are often nearly spherical particles formed by the agglomeration of primary particles, and the morphology of the primary particles, especially the particle size and particle angle distribution of the primary particles, will have a certain impact on the electrochemical performance of the cathode material. Therefore, it is necessary to develop a high nickel cathode material precursor with adjustable primary particle morphology and its preparation method and application. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a high-nickel positive electrode material precursor with adjustable primary particle morphology, and a preparation method and application thereof. The preparation method is based on a co-precipitation process, and adopts simple element doping and segmented control to prepare a high-nickel positive electrode material precursor with adjustable primary particle morphology having a specific primary particle size and angle distribution. The positive electrode material obtained by the precursor has excellent high-voltage electrochemical performance. Moreover, the preparation method of the present invention has a simple process, low manufacturing cost, and the obtained positive electrode material has excellent performance, which is convenient for large-scale production.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] One of the purposes of the present invention is to provide a method for preparing a primary particle morphology-adjustable high-nickel positive electrode material precursor, the preparation method comprising the following steps:

[0008] A nickel-cobalt-manganese mixed salt solution is prepared as solution A, and a doping solution is prepared as solution B;

[0009] The solution A, alkali solution and ammonia water are added to the reaction bottom solution in parallel to carry out the first stage of co-precipitation. After reaching the first target particle size D501, the reaction is stopped and the seed crystal is obtained by the first solid-liquid separation.

[0010] The seed crystals are put back into the reactor to form a reaction slurry, and the solution B, the solution A, the alkali solution and the ammonia water are added to the reaction slurry in parallel to perform the second stage of co-precipitation, and the reaction is stopped after the second target particle size D502 is reached;

[0011] The feed rates of the solution B, the solution A, the alkali solution and the ammonia water are increased, and they are continuously added in parallel to perform the third stage of co-precipitation. After the third target particle size D503 is reached, the reaction is stopped, and a primary particle morphology-adjustable high-nickel positive electrode material precursor is obtained through the second solid-liquid separation.

[0012] Wherein, the solution B includes a doping element M, and the doping element M is boron and / or tungsten. The doping element M doping amount Q1 of the second stage co-precipitation is 100-1000ppm, for example, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm or 1000ppm, etc., and the doping element M doping amount Q2 of the third stage co-precipitation is 500-6000ppm, for example, 500ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm, 5000ppm or 6000ppm, etc., and the doping element M doping amount Q1 is less than the doping element M doping amount Q2.

[0013] The preparation method of the present invention comprises a first stage co-precipitation, a second stage co-precipitation and a third stage co-precipitation which are performed in sequence. The first stage co-precipitation is a seed reaction stage, in which no doping solution is added. The second stage co-precipitation is a precursor growth stage, in which the particle size of the precursor is increased. A doping solution is added in this stage, but the amount of the doping solution added is smaller than that of the doping solution in the third stage. The third stage co-precipitation is a primary particle regulation stage, in which the particle size and particle angle of the primary particles on the surface can be regulated. More doping solution needs to be added in this stage.

[0014] In the preparation method of the present invention, B element and / or W element are selected as the doping element M because W doping can significantly inhibit grain growth and shorten the transmission distance of Li ions, and the synergistic effect between W and B jointly improves the rate performance of the material. By doping element M and coordinating stage-by-stage control, specifically adjusting the process parameters such as dissolved oxygen, pH value, ammonia concentration, temperature, rotation speed and the amount of doping element M added during the reaction, the particle size and particle angle of the primary particles of the positive electrode material precursor can be controlled, and the prepared high-nickel positive electrode material with specific primary particle size characteristics and angle distribution structure can effectively alleviate the stress accumulation between primary particles in the high-nickel positive electrode material under high voltage conditions, improve the lithium ion transmission efficiency, and thus make the positive electrode material have good high-voltage electrochemical performance.

[0015] It should be noted that the doping amount of the doping element M in the present invention is based on the end of each stage. By adjusting the feed flow rate of the doping element during the process, the content of the doping element at the end of each stage reaches the target value.

[0016] It should be noted that, in the preparation method of the present invention, high-purity nitrogen is continuously introduced during the reaction process; and the alkali solution is preferably a sodium hydroxide solution.

[0017] It should be noted that the reaction slurry in the preparation method of the present invention can be made into a reaction slurry by adding water to the seed crystals, or it can be made into a reaction slurry by adding the reaction base liquid required for the second stage co-precipitation to the seed crystals. It only needs to ensure the setting requirements of the reaction slurry.

[0018] As a preferred technical solution of the present invention, the chemical formula of the primary particle morphology adjustable high nickel positive electrode material precursor is Ni a Co b Mn c M d (OH)2; wherein, 0.8<a<1, 0<b<0.2, 0<c<0.2, 0<d<0.1, a+b+c+d=1.

[0019] As a preferred technical solution of the present invention, the reaction base liquid is prepared from deionized water, alkali solution and ammonia water.

[0020] Preferably, the pH value of the reaction base solution is 7.5-12, for example, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5 or 12, etc.

[0021] Preferably, the ammonia concentration of the reaction base solution is 0.1-10 g / L, for example, 0.1 g / L, 0.5 g / L, 1 g / L, 3 g / L, 5 g / L, 7 g / L, 9 g / L or 10 g / L.

[0022] Preferably, the dissolved oxygen content in the reaction bottom liquid is 100-1000 ppm, for example, 100 ppm, 300 ppm, 500 ppm, 700 ppm, 800 ppm or 1000 ppm.

[0023] Preferably, the solution A comprises a soluble nickel salt, a soluble cobalt salt, and a soluble manganese salt, and the three soluble salts are at least one of sulfate, nitrate, chloride or acetate.

[0024] Preferably, the total metal molar concentration of the solution A is 0.1-5 mol / L, such as 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L.

[0025] Preferably, the total metal ion content of the solution A is 100-120 g / L, such as 100 g / L, 105 g / L, 110 g / L, 115 g / L or 120 g / L.

[0026] As a preferred technical solution of the present invention, the solution B includes tungstate and a boron source.

[0027] Preferably, the tungstate includes at least one of ammonium tungstate, sodium tungstate or potassium tungstate.

[0028] Preferably, the boron source comprises at least one of boric acid, sodium borate or potassium borate.

[0029] Preferably, the molar ratio of tungsten element to boron element in the solution B is (1-20):1, for example, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 11:1, 13:1, 15:1, 17:1, 19:1 or 20:1, etc.

[0030] Preferably, the pH value of the solution B is 7.5-9, such as 7.5, 8.0, 8.5 or 9.0.

[0031] It should be noted that a doping solution can be obtained by adding a proper amount of soluble boron solution to a tungstate solution, and then adding a proper amount of water to make the pH of the mixed solution between 7.5 and 9 at room temperature.

[0032] As a preferred technical solution of the present invention, the reaction temperature of the first stage co-precipitation is 40-55°C, for example, 40°C, 42°C, 44°C, 45°C, 47°C, 49°C, 50°C, 52°C, 54°C or 55°C, etc.

[0033] Preferably, the reaction pH value of the first stage co-precipitation is 10-12, such as 10.0, 10.5, 11.0, 11.5 or 12.0.

[0034] Preferably, the ammonia concentration of the first stage co-precipitation is 6-10 g / L, such as 6 g / L, 7 g / L, 8 g / L, 9 g / L or 10 g / L.

[0035] Preferably, the stirring speed of the first stage co-precipitation is 350-500 rpm, for example, 350 rpm, 370 rpm, 400 rpm, 410 rpm, 430 rpm, 450 rpm, 460 rpm, 480 rpm or 500 rpm, etc.

[0036] Preferably, the first target particle size D501 is 3-4 μm, for example, 3 μm, 3.1 μm, 3.3 μm, 3.5 μm, 3.6 μm, 3.8 μm or 4 μm.

[0037] As a preferred technical solution of the present invention, the solid content of the reaction slurry is 10-200 g / L, for example, 10 g / L, 30 g / L, 50 g / L, 70 g / L, 90 g / L, 100 g / L, 130 g / L, 150 g / L, 160 g / L, 180 g / L or 200 g / L, etc.

[0038] Preferably, the pH value of the reaction slurry is 9-10, such as 9.0, 9.1, 9.3, 9.5, 9.7, 9.8 or 10.0.

[0039] Preferably, the ammonia concentration of the reaction slurry is 5-7 g / L, for example, 5 g / L, 5.5 g / L, 6 g / L, 6.5 g / L or 7 g / L.

[0040] Preferably, in the second stage of co-precipitation, the dosage of the doping solution gradually increases with the increase of the particle size during the reaction process. For every 1 micron increase in the particle size, the dosage of the doping solution increases by 45-55ppm, for example, 45ppm, 46ppm, 48ppm, 50ppm, 51ppm, 53ppm or 55ppm, etc., and the stirring speed is reduced by 25-35rpm, for example, 25rpm, 27rpm, 30rpm, 31rpm, 32rpm, 33rpm, 34rpm or 35rpm, etc.

[0041] Preferably, the reaction temperature of the second stage coprecipitation is 50-70°C, such as 50°C, 55°C, 60°C, 65°C or 70°C.

[0042] Preferably, the reaction pH value of the second stage co-precipitation is 8-11, such as 8.0, 8.5, 9.0, 9.5, 10.0, 10.5 or 11.0.

[0043] Preferably, the ammonia concentration of the second stage co-precipitation is 3-7 g / L, such as 3 g / L, 4 g / L, 5 g / L, 6 g / L or 7 g / L.

[0044] Preferably, the stirring speed of the second stage co-precipitation is 100-300 rpm, such as 100 rpm, 150 rpm, 200 rpm, 250 rpm or 300 rpm.

[0045] It should be noted that the stirring speed in the first stage is a value between 350-500rpm, which means that the stirring speed in the first stage is taken as the initial value, and the stirring speed in the second stage is reduced by 25-35rpm for every increase of 1 micron in particle size, and the stirring speed at the end of the second stage is 100-300rpm.

[0046] Preferably, the second target particle size D502 is 6-14 μm, for example, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or 14 μm.

[0047] As a preferred technical solution of the present invention, for the feed rates of the solution A, alkali solution and ammonia water, the corresponding values ​​of the third stage co-precipitation are 1.2-2 times the corresponding values ​​of the second stage co-precipitation; for the doping solution (solution B), when the second stage begins, the doping solution (solution B) is added at a certain initial feed rate, and as the particle size in the system increases, the concentration of the doping solution (solution B) remains unchanged, and only the feed rate is increased, so that the doping solution dosage increases by 45-55ppm for every 1 micron increase in particle size, and finally the total addition amount Q1 of the entire stage of the second stage co-precipitation is 100-1000ppm.

[0048] Preferably, the reaction temperature of the third stage coprecipitation is 50-70°C, such as 50°C, 55°C, 60°C, 65°C or 70°C.

[0049] Preferably, the reaction pH value of the third stage co-precipitation is 8-11, such as 8.0, 8.5, 9.0, 9.5, 10.0, 10.5 or 11.0.

[0050] Preferably, the ammonia concentration of the third stage co-precipitation is 3-7 g / L, such as 3 g / L, 4 g / L, 5 g / L, 6 g / L or 7 g / L.

[0051] Preferably, the stirring speed of the third stage co-precipitation is 80-100 rpm, such as 80 rpm, 85 rpm, 90 rpm, 95 rpm or 100 rpm.

[0052] Preferably, the third target particle size D503 is 8-18 μm, for example, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm or 18 μm.

[0053] Preferably, after the second solid-liquid separation, the method further includes washing, drying, screening and iron removal.

[0054] The preparation method of the present invention can achieve the regulation of the length, width and particle stacking angle of the precursor primary particle morphology by regulating the pH value, ammonia concentration and the amount of W and B in solution B, in combination with a suitable rotation speed and reaction atmosphere, so as to obtain a positive electrode material precursor with a specific structure. The positive electrode material calcined with the precursor will inherit the performance of the precursor and will also have a specific grain size and a specific particle angle distribution. By controlling the grain size and the particle angle, the stress accumulation between the primary particles in the positive electrode material under high nickel or high voltage conditions can be effectively alleviated, the lithium ion transmission efficiency can be improved, and the positive electrode material can have good high-voltage electrochemical performance.

[0055] The second object of the present invention is to provide a positive electrode material precursor with adjustable primary particle morphology and high nickel content, wherein the positive electrode material precursor with adjustable primary particle morphology and high nickel content is prepared by the preparation method described in the first object;

[0056] Among them, the primary particle morphology can be adjusted so that the doping element M in the nickel positive electrode material precursor presents a concentration gradient distribution that gradually increases from the inside to the outside.

[0057] As a preferred technical solution of the present invention, in the nickel positive electrode material precursor with adjustable primary particle morphology, the length of the primary particles is 0.5-2μm, for example, 0.5μm, 1μm, 1.5μm or 2μm, etc., the width is 0.06-0.5μm, for example, 0.06μm, 0.1μm, 0.2μm, 0.3μm, 0.4μm or 0.5μm, etc., and the aspect ratio is 5-12, for example, 5, 6, 7, 8, 9, 10, 11 or 12, etc.

[0058] In the primary particle morphology adjustable nickel positive electrode material precursor, the angle between two adjacent primary particles on the surface (measured in acute angle, that is, the angle between 0 and 90 degrees accounts for 100%) has the following distribution characteristics:

[0059] The angle is 0-10 degrees, accounting for less than 8%; the angle is 10-20 degrees, accounting for 10%-30%; the angle is 20-30 degrees, accounting for 10%-30%; the angle is 30-40 degrees, accounting for 10%-20%; the angle is 40-50 degrees, accounting for 5%-20%; the angle is 50-60 degrees, accounting for 5%-15%; the angle is 60-70 degrees, accounting for less than 15%; the angle is 70-80 degrees, accounting for less than 10%; the angle is 80-90 degrees, accounting for less than 10%.

[0060] The primary particle morphology adjustable high nickel positive electrode material precursor also meets the following index characteristics:

[0061] (1) The diameter distribution SPAN (i.e. (D90-D10) / D50) is between 0.2-0.6, and the tap density TD is between 1.8-2.2 g / cm 3 The specific surface area BET is between 6-12m 2 / g between;

[0062] (2) From the XRD diffraction, the diffraction intensity I 101 / I 001 The half-width (FWHM) of the main crystal planes is between 0.8 and 1.2, and the half-width (FWHM) of the 001 crystal plane is between 0.35 and 0.55, the half-width (FWHM) of the 100 crystal plane is between 0.2 and 0.5, and the half-width (FWHM) of the 101 crystal plane is between 0.25 and 0.55.

[0063] The third object of the present invention is to provide an application of a primary particle morphology adjustable high nickel positive electrode material precursor, the primary particle morphology adjustable high nickel positive electrode material precursor is mixed with a lithium source, and then pre-sintered, first ground, high temperature sintered, second ground, and sieved in sequence to obtain a high nickel positive electrode material;

[0064] Among them, the primary particle morphology can be adjusted to high nickel positive electrode material precursor is prepared by the preparation method described in purpose one; or, the primary particle morphology can be adjusted to high nickel positive electrode material precursor is the primary particle morphology can be adjusted to high nickel positive electrode material precursor described in purpose two.

[0065] Preferably, the obtained precursor is mixed evenly with a lithium source (lithium carbonate or lithium hydroxide) according to lithium (Li / metal ion molar ratio is 1-1.05), and placed in a tubular furnace for sintering, wherein the sintering atmosphere uses pure oxygen, and the sintering procedure is pre-sintering at 300-500°C for 4 hours. After the pre-sintering is completed, it is naturally cooled to room temperature, and the sample is taken out, and after simple grinding, it is continued to be sintered at high temperature. The sintering procedure is calcining at 700-900°C for 10-20 hours (for example, 10 hours, 15 hours, 20 hours, etc.), and after the sintering is completed, it is naturally cooled to room temperature. The positive electrode material can be obtained by grinding and sieving the sample.

[0066] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0067] (1) The preparation method of the present invention is based on a coprecipitation process, adopts simple element doping and segmented control, and prepares a high-nickel positive electrode material precursor with a specific primary particle size and angle distribution and adjustable primary particle morphology. The positive electrode material obtained by the precursor has excellent high-voltage electrochemical performance, can effectively alleviate the stress accumulation between primary particles in the high-nickel positive electrode material under high voltage conditions, improve the lithium ion transmission efficiency, and thus make the positive electrode material have good high-voltage electrochemical performance;

[0068] (2) The preparation method of the present invention has a simple process, low manufacturing cost, and the obtained positive electrode material has excellent performance and is convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is a SEM image of the primary particle morphology-adjustable high-nickel positive electrode material precursor prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0071] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0072] Example 1

[0073] This embodiment provides a method for preparing a high-nickel positive electrode material precursor with adjustable primary particle morphology, the preparation method comprising the following steps:

[0074] Nickel sulfate, cobalt sulfate and manganese sulfate were weighed in a stoichiometric ratio of 95:2:3, and mixed evenly with deionized water to obtain a nickel-cobalt-manganese mixed salt solution as solution A. The total metal molar concentration in solution A was controlled to be 2 mol / L, and the total metal ion amount was 110 g / L;

[0075] Add an appropriate amount of boric acid to the sodium tungstate solution, wherein the molar ratio of tungsten element to boron element is 5:1, mix well, add an appropriate amount of water, so that the pH value of the mixed solution at room temperature is about 8, and then obtain a doping solution as solution B, and the doping amount of the doping solution is 0.2wt%;

[0076] Add deionized water, sodium hydroxide solution and ammonia water into the reaction kettle to prepare a reaction base liquid, and control the pH value of the reaction base liquid to be 11-12, the ammonia concentration to be 9-10 g / L, and the dissolved oxygen content to be 1000 ppm;

[0077] The precursor was obtained by coprecipitation method, and its general chemical formula is Ni 95 Co2Mn3M(OH)2, where M is a mixture of B and W and the molar ratio of tungsten to boron in M ​​is 5:1, and the doping amount of M is 2000ppm; the prepared solution A and solution B are added to the prepared bottom liquid in the reactor according to the set stoichiometric ratio to start the reaction. During the reaction, high-purity nitrogen is continuously introduced into the reactor to start the reaction. The reaction is divided into the following three stages:

[0078] The solution A, the sodium hydroxide solution and the ammonia water are added to the reaction bottom liquid in parallel to carry out the first stage co-precipitation, the reaction temperature of the first stage co-precipitation is controlled to be 55° C., the reaction pH value is 11-12, the ammonia concentration is 9-10 g / L, the reaction speed is 450 rpm after startup, the reaction speed is reduced by 10 rpm for every 0.5 micron increase in particle size, the reaction is stopped after the reaction particle size D501 reaches 3.5 μm, and a seed crystal is obtained after the first solid-liquid separation;

[0079] The seed crystals are fed back into the reactor to form a reaction slurry, the solid content of the reaction slurry in the reactor after the back-feeding crystals is controlled to be 100 g / L, the pH value of the reaction slurry in the reactor is adjusted to 9-10, and the ammonia concentration is 5-6 g / L, the reaction temperature of the second stage coprecipitation is controlled to be 65° C., the reaction pH value is 9.8-10.2, and the ammonia concentration is 5.5-6 g / L, the reaction speed is controlled to be 300 rpm at the beginning of the second stage, the dosage of the doping solution is gradually increased as the particle size increases during the reaction, and the dosage of the doping solution is increased by 50 ppm for every 1 μm increase in particle size, and the reaction speed is reduced by 30 rpm, and the reaction is stopped after the reaction particle size D502 reaches 9.5 μm;

[0080] After the second stage, the third stage is started in the reactor. Before the start of this stage, the feed rates of solution A, sodium hydroxide solution and ammonia water are set to 1.2 times the feed rates of the second stage. Solution B is evenly added with 2000ppm in this stage. The reaction speed is controlled to be 180rpm at the beginning of the third stage coprecipitation, the reaction temperature is 65°C, the reaction pH value is between 9.8 and 10.2, the ammonia concentration is between 5.5-6g / L, and the reaction is stopped after the reaction particle size D503 is 11μm. The materials after the shutdown are washed, dried, sieved and iron removed in sequence to obtain the target precursor, that is, the primary particle morphology can be adjusted to a high nickel positive electrode material precursor;

[0081] The main physical and chemical characteristics of the precursor are: the general chemical formula is Ni 95 Co2Mn3M(OH)2, where M is a mixture of B and W and the molar ratio of tungsten to boron in M ​​is 5:1, and the M doping amount is 2000ppm; the final particle size D50 is 11μm, the diameter distribution SPAN (i.e. (D90-D10) / D50) is 0.3, and the tap density TD is 2.0g / cm 3 , the specific surface area BET is 10m 2 / g, the ratio of doping elements W and B is 5:1 and presents a gradient distribution form that gradually increases from the inside to the outside; from the XRD diffraction, its diffraction intensity I 101 / I 001 The half-peak width FWHM characteristics of the main crystal planes are 0.45 for the 001 crystal plane, 0.3 for the 100 crystal plane, and 0.38 for the 101 crystal plane.

[0082] Figure 1 The SEM image of the precursor described in this embodiment is shown, and 60 primary particles on the surface of the precursor are taken respectively, and the length, width and angle between the primary particles are statistically analyzed. The statistical results are shown in Table 1.

[0083] Example 2

[0084] This embodiment provides a method for preparing a high-nickel positive electrode material precursor with adjustable primary particle morphology. Compared with Embodiment 1, the only difference is that the second target particle size D502 is 7.5 μm, and the third target particle size D503 is 10 μm.

[0085] Example 3

[0086] This embodiment provides a method for preparing a high-nickel positive electrode material precursor. Compared with Example 1, the only difference is that the nickel-cobalt-manganese mixed salt solution, i.e., solution A, has a stoichiometric ratio of nickel sulfate, cobalt sulfate, and manganese sulfate of 90:6:4, and the total metal molar concentration is 1.5 mol / L.

[0087] Example 4

[0088] This embodiment provides a method for preparing a high-nickel positive electrode material precursor. Compared with Example 1, the only difference is that the doping solution, that is, solution B, has a pH value of 9, and the molar ratio of tungsten to boron in the solution is 4:1.

[0089] Example 5

[0090] This embodiment provides a method for preparing a high-nickel positive electrode material precursor. Compared with Example 1, the only difference is that the doping amount of the doping solution is 0.4wt%, that is, the M doping amount in the obtained precursor is 4000ppm.

[0091] Comparative Example 1

[0092] This comparative example provides a method for preparing a high-nickel positive electrode material precursor. Compared with Example 1, the only difference is that the doping amount in the second stage co-precipitation is not increased.

[0093] Comparative Example 2

[0094] This comparative example provides a method for preparing a high-nickel positive electrode material precursor. Compared with Example 1, the only difference is that the doping solution, that is, solution B, does not contain boron.

[0095] With respect to the SEM images of the precursors obtained in Examples 2-5 and Comparative Examples 1-2, 60 primary particles on the surface of the precursors were respectively taken to perform statistics on the length, width and angle between the primary particles. The statistical results are shown in Table 1.

[0096] Table 1

[0097]

[0098] The present invention provides a high-nickel positive electrode material precursor with adjustable primary particle morphology, and a preparation method and application thereof. The preparation method is based on a co-precipitation process, and adopts simple element doping and segmented control to prepare a high-nickel positive electrode material precursor with adjustable primary particle morphology having a specific primary particle size and angle distribution. The positive electrode material obtained by the precursor has excellent high-voltage electrochemical performance. Moreover, the preparation method of the present invention has a simple process, low manufacturing cost, and the obtained positive electrode material has excellent performance, which is convenient for large-scale production.

[0099] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0100] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0101] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0102] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a high-nickel cathode material precursor with adjustable primary particle morphology, characterized in that: The preparation method comprises the following steps: A nickel-cobalt-manganese mixed salt solution is prepared as solution A, and a doping solution is prepared as solution B; The solution A, alkali solution and ammonia water are added to the reaction bottom solution in parallel to carry out the first stage of co-precipitation. After reaching the first target particle size D501, the reaction is stopped and the seed crystal is obtained by the first solid-liquid separation. The seed crystals are put back into the reactor to form a reaction slurry, and the solution B, the solution A, the alkali solution and the ammonia water are added to the reaction slurry in parallel to perform the second stage of co-precipitation, and the reaction is stopped after the second target particle size D502 is reached; The feed rates of the solution B, the solution A, the alkali solution and the ammonia water are increased, and they are continuously added in parallel to perform the third stage of co-precipitation. After the third target particle size D503 is reached, the reaction is stopped, and a primary particle morphology-adjustable high-nickel positive electrode material precursor is obtained through the second solid-liquid separation. Wherein, the solution B includes a doping element M, the doping element M is boron and / or tungsten, the doping element M doping amount Q1 of the second stage co-precipitation is 100-1000ppm, the doping element M doping amount Q2 of the third stage co-precipitation is 500-6000ppm, and the doping element M doping amount Q1 is less than the doping element M doping amount Q2.

2. The preparation method according to claim 1, characterized in that: The chemical formula of the primary particle morphology adjustable nickel positive electrode material precursor is Ni a Co b Mn c M d (OH)2; wherein, 0.8<a<1, 0<b<0.2, 0<c<0.2, 0<d<0.1, a+b+c+d=1.

3. The preparation method according to claim 1 or 2, characterized in that: The reaction base solution is prepared from deionized water, alkali solution and ammonia water; Preferably, the pH value of the reaction base solution is 7.5-12; Preferably, the ammonia concentration of the reaction base solution is 0.1-10 g / L; Preferably, the dissolved oxygen content in the reaction bottom liquid is 100-1000 ppm; Preferably, the total metal molar concentration of the solution A is 0.1-5 mol / L; Preferably, the total metal ion content of the solution A is 100-120 g / L.

4. The preparation method according to any one of claims 1 to 3, characterized in that The solution B includes tungstate and a boron source; Preferably, the tungstate includes at least one of ammonium tungstate, sodium tungstate or potassium tungstate; Preferably, the boron source comprises at least one of boric acid, sodium borate or potassium borate; Preferably, the molar ratio of tungsten element to boron element in the solution B is (1-20):1; Preferably, the pH value of solution B is 7.5-9.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The reaction temperature of the first stage coprecipitation is 40-55°C; Preferably, the reaction pH value of the first stage coprecipitation is 10-12; Preferably, the ammonia concentration of the first stage co-precipitation is 6-10 g / L; Preferably, the stirring speed of the first stage coprecipitation is 350-500 rpm; Preferably, the first target particle size D501 is 3-4 μm.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The solid content of the reaction slurry is 10-200 g / L; Preferably, the pH value of the reaction slurry is 9-10; Preferably, the ammonia concentration of the reaction slurry is 5-7 g / L; Preferably, in the second stage of co-precipitation, the dosage of the doping solution gradually increases with the increase of the particle size during the reaction process. For every 1 micron increase in particle size, the dosage of the doping solution increases by 45-55 ppm, and the stirring speed decreases by 25-35 rpm. Preferably, the reaction temperature of the second stage coprecipitation is 50-70°C; Preferably, the reaction pH value of the second stage coprecipitation is 8-11; Preferably, the ammonia concentration of the second stage co-precipitation is 3-7 g / L; Preferably, the stirring speed of the second stage coprecipitation is 100-300 rpm; Preferably, the second target particle size D502 is 6-14 μm.

7. The preparation method according to any one of claims 1 to 6, characterized in that: For the feed rates of solution A, alkali solution and ammonia water, the corresponding values ​​of the third stage co-precipitation are 1.2-2 times the corresponding values ​​of the second stage co-precipitation; Preferably, the reaction temperature of the third stage coprecipitation is 50-70°C; Preferably, the reaction pH value of the third stage coprecipitation is 8-11; Preferably, the ammonia concentration of the third stage co-precipitation is 3-7 g / L; Preferably, the stirring speed of the third stage coprecipitation is 80-100 rpm; Preferably, the third target particle size D503 is 8-18 μm.

8. A primary particle morphology adjustable high nickel positive electrode material precursor, characterized in that: The primary particle morphology adjustable high nickel positive electrode material precursor is prepared by the preparation method according to any one of claims 1 to 7; Among them, the primary particle morphology can be adjusted so that the doping element M in the nickel positive electrode material precursor presents a concentration gradient distribution that gradually increases from the inside to the outside.

9. The primary particle morphology adjustable high nickel positive electrode material precursor according to claim 8, characterized in that: In the nickel positive electrode material precursor with adjustable primary particle morphology, the length of the primary particles is 0.5-2 μm, the width is 0.06-0.5 μm, and the aspect ratio is 5-12; In the primary particle morphology adjustable nickel positive electrode material precursor, the angle between two adjacent primary particles on the surface has the following distribution characteristics: The angle is 0-10 degrees, accounting for less than 8%; the angle is 10-20 degrees, accounting for 10%-30%; the angle is 20-30 degrees, accounting for 10%-30%; the angle is 30-40 degrees, accounting for 10%-20%; the angle is 40-50 degrees, accounting for 5%-20%; the angle is 50-60 degrees, accounting for 5%-15%; the angle is 60-70 degrees, accounting for less than 15%; the angle is 70-80 degrees, accounting for less than 10%; the angle is 80-90 degrees, accounting for less than 10%.

10. An application of a primary particle morphology adjustable high nickel positive electrode material precursor, characterized in that: The primary particle morphology adjustable high nickel cathode material precursor is mixed evenly with a lithium source, and the mixture is subjected to pre-sintering, first grinding, high temperature sintering, second grinding, and screening in sequence to obtain a high nickel cathode material; Among them, the primary particle morphology adjustable high nickel positive electrode material precursor is prepared by the preparation method described in any one of claims 1-7; or, the primary particle morphology adjustable high nickel positive electrode material precursor is the primary particle morphology adjustable high nickel positive electrode material precursor described in claim 8 or 9.

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