High tap density small particle size cathode material precursors, cathode materials and preparation methods, lithium-ion batteries and related equipment

Abstract

This application provides a high-tap-density, small-particle-size cathode material precursor, a cathode material and its preparation method, a lithium-ion battery, and electrical-related devices. The high-tap-density, small-particle-size cathode material precursor satisfies the following condition: TD / D50 > 0.9 g / (cm³). 3 The high-tap-density, small-particle-size cathode material precursor has a diameter of 1.0 μm and a density of D50 ≤ 2.0 μm. The preparation method includes: preparing a base solution by mixing a precipitant and a complexing agent; adding a metal salt solution, precipitant, and complexing agent to the base solution; controlling the pH, ammonia concentration, stirring speed, and material flow rate of the system; and reacting to obtain the precursor. The high-tap-density, small-particle-size cathode material precursor provided in this application has both small particle size and ultra-high tap density, which can increase the amount of active material per unit volume of cathode material and improve the volumetric energy density of small particles.

Description

Technical Field

[0001] This application relates to the field of materials, and in particular to a high tap density small particle size cathode material precursor, cathode material and preparation method, lithium-ion battery and electrical equipment. Background Technology

[0002] New energy vehicles have become a major direction for the transformation and development of the global automotive industry and an important engine for promoting sustained global economic growth. Lithium-ion batteries are the core of new energy vehicles, and as people's demands for the driving range of these vehicles increase, improving energy density is particularly important. The physicochemical properties of the cathode material precursor are crucial for improving the capacity performance and energy density of the cathode material itself. Summary of the Invention

[0003] The purpose of this application is to provide a high tap density, small particle size cathode material precursor, cathode material and preparation method, lithium-ion battery and electrical equipment to solve the above problems.

[0004] To achieve the above objectives, this application adopts the following technical solution:

[0005] A high tap density, small particle size cathode material precursor, wherein the cathode material precursor satisfies the following conditions:

[0006] TD / D50 is 0.9-3.0 g / (cm³). 3 ·μm), D50≤2.0μm.

[0007] Optionally, the cathode material precursor satisfies one or more of the following conditions:

[0008] A. The TD of the cathode material precursor is ≥1.5 g / cm³. 3 ≥1.7g / cm 3 ;

[0009] B. The D90 of the cathode material precursor is 1.0-4.5μm, and can be selected as 2.0-3.2μm;

[0010] C. The D90 / D50 of the cathode material precursor is <2.5, and can be ≤1.8;

[0011] D. The ratio of (D90-D10) / D50 of the cathode material precursor is 0.3-1.5, and can be selected as 0.8-1.2.

[0012] Optionally, the cathode material precursor satisfies one or more of the following conditions:

[0013] (1) The overall porosity of the secondary particles of the cathode material precursor is 5%-30%, and can be selected as 10%-20%;

[0014] (2) The cathode material precursor has a core and a shell covering the core, wherein the porosity of the core is greater than that of the shell; optionally, the porosity of the core is 15%-50%; optionally, the porosity of the shell is 3%-10%; optionally, the difference between the porosity of the core and the shell is 5%-20%.

[0015] (3) The secondary particles of the cathode material precursor are composed of elongated primary particles arranged radially.

[0016] Optionally, the average length of the primary particle is 200-500 nm; optionally, the average width of the primary particle is 50-150 nm; optionally, the average aspect ratio of the primary particle is (2-10):1.

[0017] (4) The BET of the cathode material precursor is 2-20m. 2 / g, 8-18m available 2 / g;

[0018] (5) The cathode material precursor has a core and a shell covering the core, the diameter of the core is 0.8-1.5μm and the thickness of the shell is 0.2-0.8μm.

[0019] Optionally, the cathode material precursor satisfies one or more of the following conditions:

[0020] (6) The cathode material precursor is a nickel-containing hydroxide; optionally, the cathode material precursor also contains a cobalt and / or manganese hydroxide.

[0021] (7) The nickel element in the cathode material precursor accounts for more than 80% of the total molar content of metal elements, and may be more than 90%;

[0022] (8) The chemical formula of the cathode material precursor is Ni x Co y Mn z M p (OH)2, wherein 0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, 0≤p≤0.05, x+y+z+p=1; M is a dopant element, which includes one or more of W, Zr, Mg, Al, Ti, and Y; optionally, x≥0.8;

[0023] This application also provides a method for preparing the high tap density, small particle size cathode material precursor described above, comprising:

[0024] A base solution was prepared by precipitating agent and complexing agent. Metal salt solution, precipitating agent and complexing agent were added to the base solution. The pH, ammonia concentration, stirring speed and material flow rate of the system were controlled. The high tap density small particle size cathode material precursor was obtained by co-precipitation method.

[0025] Optionally, the preparation method of the high tap density small particle size cathode material precursor satisfies one or more of the following conditions:

[0026] a. The coprecipitation method is intermittent;

[0027] b. The metal salt solution includes one or more of nickel salts and cobalt salts, manganese salts, and doping element salts corresponding to the target precursor;

[0028] c. The total concentration of metal ions in the metal salt solution is 100-120 g / L;

[0029] d. The precipitant includes sodium hydroxide, and the complexing agent includes ammonia, wherein the mass percentage concentration of the ammonia is 15%-25%;

[0030] e. The pH of the substrate solution is 11.8-12.3, and the pH of the reaction is 11.1-11.5;

[0031] f. The ammonia concentration is 3.0-5.8 g / L; here, the ammonia concentration refers to the concentration of ammonia water, calculated in the form of NH3;

[0032] g. The reaction temperature is 40-55℃;

[0033] h. The stirring speed is 400-600 rpm;

[0034] i. The flow rate of the metal salt solution is 2%-4.5% / h of the reaction vessel volume, the flow rate of the precipitant is 1%-1.5% / h of the reaction vessel volume, and the flow rate of the complexing agent is 0.10%-0.15% / h of the reaction vessel volume.

[0035] This application also provides a cathode material, the raw material of which includes the high tap density small particle size cathode material precursor described above.

[0036] This application also provides a method for preparing the aforementioned cathode material, comprising:

[0037] The high tap density, small particle size cathode material precursor is mixed with a lithium source and sintered to obtain the cathode material.

[0038] Optionally, the sintering temperature is 500-650℃ and the time is 10-15h.

[0039] This application also provides a lithium-ion battery, the raw materials of which include the aforementioned positive electrode material.

[0040] This application also provides an electrical device, including the aforementioned lithium-ion battery.

[0041] Compared with the prior art, the beneficial effects of this application include:

[0042] The high tap density, small particle size cathode material precursor provided in this application satisfies TD / D50 > 0.9 g / (cm³). 3 Precursors with smaller particle sizes (·μm) and D50≤2.0μm have a relatively larger surface area, which is beneficial for achieving sufficient contact with the electrolyte, providing more reactive active sites, and improving their discharge specific capacity. In addition, under the condition of small particle size, they also have higher tap density, which can increase the amount of active material per unit volume of cathode material and improve the volumetric energy density of small particles. Therefore, by simultaneously satisfying a higher TD / D50 ratio and a smaller D50, higher energy density can be ensured.

[0043] The method for preparing high tap density small particle size cathode material precursor provided in this application adopts a co-precipitation method, controls the pH, ammonia concentration, stirring speed and material flow rate of the system, and obtains high tap density small particle size cathode material precursor. The method is simple and low cost.

[0044] The cathode material, lithium-ion battery, and electrical equipment provided in this application have excellent electrical performance.

[0045] The method for preparing the cathode material provided in this application uses the above-mentioned high tap density small particle size cathode material precursor and lithium source as raw materials, and the sintering temperature is low. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0047] Figure 1 This is a SEM image of the precursor obtained in Example 1;

[0048] Figure 2 The CP diagram of the precursor obtained in Example 1;

[0049] Figure 3 Here is a SEM image of the precursor obtained in Example 2;

[0050] Figure 4 The CP diagram of the precursor obtained in Example 2;

[0051] Figure 5Here is a SEM image of the precursor obtained in Example 3;

[0052] Figure 6 Here is a SEM image of the precursor obtained in Comparative Example 1;

[0053] Figure 7 Here is a SEM image of the precursor obtained in Comparative Example 2;

[0054] Figure 8 The CP diagram of the precursor obtained in Comparative Example 2;

[0055] Figure 9 Here is a SEM image of the precursor obtained in Comparative Example 3;

[0056] Figure 10 The CP diagram of the precursor obtained in Comparative Example 3;

[0057] Figure 11 Here is a SEM image of the precursor obtained in Comparative Example 4;

[0058] Figure 12 The image shows the SEM image of the precursor obtained in Comparative Example 5. Detailed Implementation

[0059] First, the technical solution provided in this application will be described in its entirety:

[0060] A high tap density, small particle size cathode material precursor, wherein the cathode material precursor satisfies the following conditions:

[0061] TD / D50 is 0.9-3.0 g / (cm³). 3 ·μm), D50≤2.0μm.

[0062] The test method for tap density is as follows: instrument model BT303 / 302, vibration amplitude 3mm, vibration frequency 249r / min, vibration number 3000 times, temperature 15-30℃, humidity ≤70%.

[0063] Optionally, the positive electrode material precursor TD / D50 can be, for example, 0.91 g / (cm³). 3 ·μm), 0.95g / (cm 3 ·μm), 1.00g / (cm 3 ·μm), 1.05g / (cm) 3 ·μm), 1.10g / (cm) 3 ·μm), 1.15g / (cm) 3 ·μm), 1.20g / (cm) 3 ·μm), 1.25g / (cm 3 ·μm), 1.30g / (cm 3·μm) and other values ​​greater than 0.9 g / (cm) 3 The value of D50 (·μm) can be 0.1μm, 0.5μm, 1μm, 1.5μm, 2.0μm or any value less than or equal to 2.0μm.

[0064] In an optional implementation, the cathode material precursor satisfies one or more of the following conditions:

[0065] A. The TD of the cathode material precursor is ≥1.5 g / cm³. 3 ≥1.7g / cm 3 ;

[0066] Optionally, the TD of the cathode material precursor can be, for example, 1.5 g / cm³. 3 1.55g / cm 3 1.6g / cm 3 1.65g / cm 3 1.7g / cm 3 1.75g / cm 3 1.8g / cm 3 1.85g / cm 3 1.9g / cm 3 1.95g / cm 3 2.00g / cm 3 ≥1.5g / cm 3 The value of .

[0067] B. The D90 of the cathode material precursor is 1.0-4.5μm, and can be selected as 2.0-3.2μm;

[0068] Optionally, the D90 of the cathode material precursor can be any value between 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.0-4.0 μm.

[0069] C. The D90 / D50 of the cathode material precursor is <2.5, and can be ≤1.8;

[0070] Optionally, the D90 / D50 of the cathode material precursor can be any value of 0.1, 0.5, 1.0, 1.5, 2.0 or less than 2.0.

[0071] D. The ratio of (D90-D10) / D50 of the cathode material precursor is 0.3-1.5, and can be selected as 0.8-1.2.

[0072] Smaller particle size distribution indicates better particle uniformity and a more stable overall structure, which is beneficial for improving cycle stability performance.

[0073] Optionally, the (D90-D10) / D50 of the cathode material precursor can be any value between 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or 0.3-1.5.

[0074] In an optional implementation, the cathode material precursor satisfies one or more of the following conditions:

[0075] (1) The overall porosity of the secondary particles of the cathode material precursor is 5%-30%, and can be selected as 10%-20%;

[0076] The precursor particles have a denser overall structure, better compressive strength during cycling, and a more stable structure.

[0077] Optionally, the porosity of the secondary particles of the cathode material precursor can be any value between 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or 5-20%.

[0078] (2) The cathode material precursor has a core and a shell covering the core, wherein the porosity of the core is greater than that of the shell; optionally, the porosity of the core is 15%-50%; optionally, the porosity of the shell is 3%-10%; optionally, the difference between the porosity of the core and the shell is 5%-20%.

[0079] The precursor material is designed to be loose inside (core) and compact outside (shell), exhibiting a radial structure, thus characterizing a loose inside and compact outside morphology, which is beneficial for maintaining good cycle performance.

[0080] Optionally, the porosity of the core can be any value between 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 15%-50%, and the porosity of the shell can be any value between 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or 3%-10%.

[0081] The porosity testing method is as follows: Using image analysis software (ImageJ), the pore area and cross-sectional area of ​​a CP cross-section at a magnification of N times (e.g., 30,000-50,000 times) are directly calculated. The porosity of different regions is then calculated using the formula: "Porosity = Pore area of ​​each region / Cross-sectional area of ​​each region × 100%". Several CP images (e.g., 5 images) can be used to calculate the porosity, and then the average value is taken. All porosities mentioned in the instruction manual are obtained using this method.

[0082] (3) The secondary particles of the cathode material precursor are composed of elongated primary particles arranged radially thereon; optionally, the average length of the primary particles is 200-500 nm; optionally, the average width of the primary particles is 50-150 nm; optionally, the average aspect ratio of the primary particles is (2-10):1.

[0083] Optionally, the average length of the primary particle can be any value between 200nm, 300nm, 400nm, 500nm or 200-500nm, the average width can be any value between 50nm, 100nm, 120nm or 50-150nm, and the average aspect ratio can be any value between 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or (2-10):1.

[0084] The primary particles are elongated strips with suitable length and width, and are arranged radially, which helps to shorten the lithium-ion transport path and maintain good capacity performance.

[0085] The method for testing the length and width of primary particles is as follows: Using Nano Measurer software, measure the length and width of primary particles on the surface of secondary particles in SEM images with magnifications of 50,000-150,000. The longest axis of a single primary particle is considered its length, and the shortest axis measured perpendicular to the midpoint of the longest axis is considered its width. At least 10 primary particle data points (one group) should be taken from each SEM image. Several SEM images (e.g., 5 images) can be used for calculation, resulting in 5 groups. The average value is then taken to obtain the average width and average length of the primary particles, and the average aspect ratio is calculated. The average length and average width of the primary particles in the instruction manual are obtained using this method.

[0086] (4) The BET of the cathode material precursor is 2-20m. 2 / g, 8-18m available 2 / g;

[0087] High-nickel cathode materials generally require higher sintering temperatures due to their high nickel content. During the sintering process, the increased temperature can adversely affect the crystal structure, severely disrupting its consistency and leading to reduced cycle performance.

[0088] Having both ultra-high tap density and appropriate specific surface area is beneficial for sufficient contact with the electrolyte, shortening the electrolyte transport path and maximizing capacity. Increasing the specific surface area of ​​the high-nickel cathode precursor may provide more pore structure, which is beneficial for promoting the sintering mass transfer process, reducing the sintering temperature of the cathode material, and maintaining the consistency of the crystal structure, thereby improving its cycle performance and safety performance. In addition, a larger pore structure is also beneficial for improving rate performance.

[0089] Optionally, the BET of the cathode material precursor can be 2m. 2 / g、3m 2 / g、4m 2 / g、5m 2 / g、6m 2 / g、7m 2 / g、8m 2 / g、9m 2 / g, 10m 2 / g、11m 2 / g、12m 2 / g、13m 2 / g、14m 2 / g, 15m 2 / g, 16m 2 / g、17m 2 / g、18m 2 / g、19m 2 / g、20m 2 / g or 2-20m 2 Any value between / g.

[0090] (5) The cathode material precursor has a core and a shell covering the core, the diameter of the core is 0.8-1.5μm and the thickness of the shell is 0.2-0.8μm.

[0091] Optionally, the diameter of the core can be any value between 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, or 0.8-1.5μm, and the thickness of the shell can be any value between 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, or 0.2-0.8μm.

[0092] In an optional implementation, the cathode material precursor satisfies one or more of the following conditions:

[0093] (6) The cathode material precursor is a nickel-containing hydroxide; optionally, the cathode material precursor also contains a cobalt and / or manganese hydroxide.

[0094] (7) The nickel element in the cathode material precursor accounts for more than 80% of the total molar content of metal elements, and may be more than 90%;

[0095] (8) The chemical formula of the cathode material precursor is Ni x Co y Mn z M p(OH)2, wherein 0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, 0≤p≤0.05, x+y+z+p=1; M is a dopant element, which includes one or more of W, Zr, Mg, Al, Ti, and Y; optionally, x≥0.8;

[0096] Optionally, x can be 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or any value greater than or equal to 0.5 and less than 1; y can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0. 30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, or any value between 0 and 0.5; z can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.1 9, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, or any value between 0 and 0.5; p can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, or any value between 0 and 0.05.

[0097] High-nickel products have advantages such as high energy density, and can also be doped with various metal elements, making them more widely used.

[0098] This application also provides a method for preparing the high tap density, small particle size cathode material precursor described above, comprising:

[0099] A base solution was prepared by precipitating agent and complexing agent. Metal salt solution, precipitating agent and complexing agent were added to the base solution. The pH, ammonia concentration, stirring speed and material flow rate of the system were controlled. The high tap density small particle size cathode material precursor was obtained by co-precipitation method.

[0100] In an optional embodiment, the method for preparing the high tap density, small particle size cathode material precursor satisfies one or more of the following conditions:

[0101] a. The coprecipitation method is intermittent;

[0102] b. The metal salt solution includes one or more of nickel salts and cobalt salts, manganese salts, and doping element salts corresponding to the target precursor;

[0103] c. The total concentration of metal ions in the metal salt solution is 100-120 g / L;

[0104] d. The precipitant includes sodium hydroxide, and the complexing agent includes ammonia, wherein the mass percentage concentration of the ammonia is 15%-25%;

[0105] e. The pH of the substrate solution is 11.8-12.3, and the pH of the reaction is 11.1-11.5;

[0106] f. The ammonia concentration is 3.0-5.8 g / L;

[0107] g. The reaction temperature is 40-55℃;

[0108] h. The stirring speed is 400-600 rpm;

[0109] i. The flow rate of the metal salt solution is 2%-4.5% / h of the reaction vessel volume, the flow rate of the precipitant is 1%-1.5% / h of the reaction vessel volume, and the flow rate of the complexing agent is 0.10%-0.15% / h of the reaction vessel volume.

[0110] Optionally, the mass percentage concentration of the ammonia solution can be any value between 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, or 15%-25%; the pH of the base solution can be between 11.8, 11.9, 12.0, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, or 11.8-12.8. The pH of the reaction can be any value of 11.1, 11.2, 11.3, 11.4, 11.5, or any value between 11.1 and 11.5; the ammonia concentration can be any value of 3.0 g / L, 3.5 g / L, 4.0 g / L, 4.5 g / L, 5.0 g / L, 5.5 g / L, 5.8 g / L, or any value between 3.0 and 5.8 g / L; the reaction temperature can be 40°C, 45°C, 50°C, or... The temperature can be any value between 55℃ and 40-55℃; the stirring speed can be any value between 400 rpm, 450 rpm, 500 rpm, or 400-600 rpm; the flow rate of the metal salt solution can be any value between 2% / h, 2.5% / h, 3.0% / h, 3.5% / h, 4.0% / h, 4.5% / h, or 2%-4.5% / h of the reaction vessel volume; the flow rate of the precipitant... The amount can be any value between 1% / h, 1.1% / h, 1.2% / h, 1.3% / h, 1.4% / h, 1.5% / h, or 1%-1.5% / h of the reaction vessel volume, and the flow rate of the complexing agent can be any value between 0.10% / h, 0.11% / h, 0.12% / h, 0.13% / h, 0.14% / h, 0.15% / h, or 0.10%-0.15% / h of the reaction vessel volume.

[0111] This application also provides a cathode material, the raw material of which includes the high tap density small particle size cathode material precursor described above.

[0112] This application also provides a method for preparing the aforementioned cathode material, comprising:

[0113] The high tap density, small particle size cathode material precursor is mixed with a lithium source and sintered to obtain the cathode material.

[0114] In one optional embodiment, the sintering temperature is 500-650°C and the time is 10-15 hours.

[0115] Optionally, the sintering temperature can be 500℃, 550℃, 600℃, 650℃ or 500-650℃, and the time can be 10h, 11h, 12h, 13h, 14h, 15h or 10-15h.

[0116] This application also provides a lithium-ion battery, the raw materials of which include the aforementioned positive electrode material.

[0117] This application also provides an electrical device, including the aforementioned lithium-ion battery.

[0118] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0119] Example 1

[0120] This embodiment provides a high tap density, small particle size cathode material precursor, the preparation method of which is as follows:

[0121] Nickel sulfate, cobalt sulfate and pure water were mixed and stirred until homogeneous. A metal salt solution was prepared according to the molar ratio Ni:Co = 98:2, in which the sum of the mass concentrations of the metal ions was 120 g / L.

[0122] Pure water, sodium hydroxide solution (mass percentage concentration of 16.0%), and ammonia solution (mass percentage concentration of 15.4%) were added to the reactor to prepare a base solution with a pH value of 11.85 and an ammonia concentration of 3.0 g / L. Argon gas was introduced as a protective gas, and the reaction temperature was 50℃.

[0123] The stirring speed of the reaction process was adjusted to 400 r / min. Metal salt solution (3% / h of reactor volume), sodium hydroxide solution (1.20% / h of reactor volume), and ammonia water (0.12% / h of reactor volume) were introduced at the set flow rates, and the pH value of the reaction process was controlled at 11.10. The reaction continued until a binary high-nickel nickel-cobalt hydroxide precursor precipitate with a particle size D50 of 1.7 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.98 Co 0.02 (OH)2.

[0124] Figure 1 This is a SEM image of the precursor obtained in Example 1; Figure 2 The image shows the CP diagram of the precursor obtained in Example 1.

[0125] This embodiment also provides a lithium-ion battery cathode material, the preparation method of which is as follows:

[0126] The precursor material obtained above was mixed with lithium hydroxide in a molar ratio of 1:1.05 and sintered at 580°C for 12 hours to prepare a lithium-ion battery cathode material.

[0127] The preparation methods of the cathode materials in subsequent embodiments and comparative examples are the same as those in this embodiment.

[0128] Example 2

[0129] The main difference between Example 2 and Example 1 is that the reaction stirring speed was changed. Specifically:

[0130] Nickel sulfate, cobalt sulfate, manganese sulfate and pure water are mixed and stirred until homogeneous. A metal salt solution is prepared according to the molar ratio Ni:Co:Mn = 96:3:1, in which the sum of the mass concentrations of the metal ions is 120 g / L.

[0131] Pure water, sodium hydroxide solution (19.5% by mass), and ammonia solution (15.5% by mass) were added to the reactor to prepare a base solution with a pH of 11.85 and an ammonia concentration of 3.0 g / L. Nitrogen gas was introduced as a protective gas, and the reaction temperature was 50℃.

[0132] The stirring speed of the reaction process was adjusted to 420 r / min. Metal salt solution (3% / h of reactor volume), sodium hydroxide solution (1.2% / h of reactor volume), and ammonia water (0.12% / h of reactor volume) were introduced at the set flow rates, and the pH of the reaction process was controlled at 11.10. The reaction continued until a ternary high-nickel nickel hydroxide nickel-cobalt-manganese precursor precipitate with a particle size D50 of 1.7 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.96 Co 0.03 Mn 0.01 (OH)2.

[0133] Figure 3 Here is a SEM image of the precursor obtained in Example 2; Figure 4 The image shows the CP diagram of the precursor obtained in Example 2.

[0134] Example 3

[0135] The main difference between the preparation method in Example 3 and that in Example 1 is the change in the reaction flow rate. Details are as follows:

[0136] Nickel sulfate, cobalt sulfate and pure water were mixed and stirred until homogeneous. A metal salt solution was prepared according to the molar ratio Ni:Co:Mn = 98:1.5:0.5, in which the sum of the mass concentrations of the metal ions was 110 g / L.

[0137] Pure water, sodium hydroxide solution (22% by mass), and ammonia solution (17.5% by mass) were added to the reactor to prepare a base solution with a pH of 12.15 and an ammonia concentration of 5.5 g / L. Nitrogen gas was introduced as a protective gas, and the reaction temperature was 45℃.

[0138] The stirring speed of the reaction process was adjusted to 400 r / min. Metal salt solution (4% / h of reactor volume), sodium hydroxide solution (1.5% / h of reactor volume), and ammonia water (0.2% / h of reactor volume) were introduced at the set flow rates, and the pH of the reaction process was controlled at 11.20. The reaction continued until a ternary high-nickel nickel hydroxide nickel-cobalt-manganese precursor precipitate with a particle size D50 of 1.7 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.98 Co 0.015 Mn 0.005 (OH)2.

[0139] Figure 5 This is a SEM image of the precursor obtained in Example 3.

[0140] Comparative Example 1

[0141] The main difference between Comparative Example 1 and Example 1 is that the initial pH was changed, resulting in an increase in particle size. Details are as follows:

[0142] Nickel sulfate, cobalt sulfate, manganese sulfate and pure water were mixed and stirred until homogeneous. A metal salt solution was prepared according to the molar ratio Ni:Co:Mn = 94:4:2, in which the sum of the mass concentrations of the metal ions was 120 g / L.

[0143] Pure water, sodium hydroxide solution (mass percentage concentration of 13.0%), and ammonia solution (mass percentage concentration of 10.5%) were added to the reactor to prepare a base liquid with a pH value of 11.95 and an ammonia concentration of 6.0 g / L. Argon gas was introduced as a protective gas, and the reaction temperature was 50℃.

[0144] The stirring speed of the reaction process was adjusted to 400 r / min. Metal salt solution (3% / h of reactor volume), sodium hydroxide solution (1.2% / h of reactor volume), and ammonia water (0.12% / h of reactor volume) were introduced at the set flow rates, and the pH of the reaction process was controlled at 11.60. The reaction continued until a ternary high-nickel nickel-cobalt hydroxide precursor precipitate with a particle size D50 of 2.2 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.94 Co 0.04 Mn 0.02 (OH)2.

[0145] Figure 6 The image shows the SEM image of the precursor obtained in Comparative Example 1.

[0146] Comparative Example 2

[0147] The main difference between Comparative Example 2 and Example 1 is that the reaction flow rate and pH were changed. Details are as follows:

[0148] Nickel sulfate, cobalt sulfate and pure water were mixed and stirred to prepare a metal salt solution with a molar ratio of Ni:Co = 95:5, wherein the sum of the mass concentrations of the metal ions was 115 g / L.

[0149] Pure water, sodium hydroxide solution (mass percentage concentration of 18.9%), and ammonia solution (mass percentage concentration of 11.8%) were added to the reactor to prepare a base solution with a pH value of 11.95 and an ammonia concentration of 3.0 g / L. Nitrogen gas was introduced as a protective gas, and the reaction temperature was 60℃.

[0150] The stirring speed of the reaction process was adjusted to 400 r / min. Metal salt solution (5% / h of reactor volume), sodium hydroxide solution (2.3% / h of reactor volume), and ammonia water (0.12% / h of reactor volume) were introduced at the set flow rates, and the pH of the reaction process was controlled at 10.20. The reaction continued until a binary high-nickel nickel-cobalt hydroxide precursor precipitate with a particle size D50 of 1.8 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.95 Co 0.05 (OH)2.

[0151] Figure 7 Here is a SEM image of the precursor obtained in Comparative Example 2; Figure 8 The CP diagram is for the precursor obtained in Comparative Example 2.

[0152] Comparative Example 3

[0153] The main difference between Comparative Example 3 and Example 1 lies in the change of ammonia concentration and stirring speed. Details are as follows:

[0154] Nickel sulfate, cobalt sulfate and pure water were mixed and stirred until homogeneous. A metal salt solution was prepared according to the molar ratio Ni:Co = 98:2, in which the sum of the mass concentrations of the metal ions was 120 g / L.

[0155] Pure water, sodium hydroxide solution (mass percentage concentration of 16%), and ammonia solution (mass percentage concentration of 15.4%) were added to the reactor to prepare a base solution with a pH value of 11.75 and an ammonia concentration of 8.0 g / L. Nitrogen gas was introduced as a protective gas, and the reaction temperature was 50℃.

[0156] The stirring speed of the reaction process was adjusted to 350 r / min. Metal salt solution (4% / h of reactor volume), sodium hydroxide solution (1.6% / h of reactor volume), and ammonia water (0.15% / h of reactor volume) were introduced at the set flow rates, and the pH of the reaction process was controlled at 10.90. The reaction continued until a binary high-nickel nickel-cobalt hydroxide precursor precipitate with a particle size D50 of 4.2 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.98 Co 0.02 (OH)2.

[0157] Figure 9 Here is a SEM image of the precursor obtained in Comparative Example 3; Figure 10 The CP diagram is for the precursor obtained in Comparative Example 3.

[0158] Comparative Example 4

[0159] The main difference between Comparative Example 4 and Example 1 is that the solution ratio was changed. Specifically:

[0160] Nickel sulfate, manganese sulfate and pure water are mixed and stirred to prepare a metal salt solution with a molar ratio of Ni:Mn = 50:50, wherein the sum of the mass concentrations of the metal ions is 120 g / L.

[0161] Pure water, sodium hydroxide solution (mass percentage concentration of 16%), and ammonia solution (mass percentage concentration of 15.4%) were added to the reactor to prepare a base solution with a pH value of 11.65 and an ammonia concentration of 3.0 g / L. Nitrogen gas was introduced as a protective gas, and the reaction temperature was 60℃.

[0162] The stirring speed of the reaction process was adjusted to 350 r / min. Metal salt solution (4% / h of reactor volume), sodium hydroxide solution (1.6% / h of reactor volume), and ammonia water (0.15% / h of reactor volume) were introduced at the set flow rates, and the pH of the reaction process was controlled at 10.80. The reaction continued until a binary nickel-cobalt hydroxide precursor precipitate with a particle size D50 of 2.8 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.50 Mn 0.50 (OH)2.

[0163] Figure 11 The image shows the SEM image of the precursor obtained in Comparative Example 4.

[0164] Comparative Example 5

[0165] The preparation methods of the precursor and cathode material in Comparative Example 5 are detailed below:

[0166] Nickel sulfate, cobalt sulfate and pure water were mixed and stirred until homogeneous. A metal salt solution was prepared according to the molar ratio Ni:Co:Mn = 94:5:1, in which the sum of the mass concentrations of the metal ions was 110 g / L.

[0167] Pure water, sodium hydroxide solution (mass percentage concentration of 14.6%), and ammonia solution (mass percentage concentration of 17.5%) were added to the reactor to prepare a base solution with a pH value of 11.90 and an ammonia concentration of 3.0 g / L. Argon gas was introduced as a protective gas, and the reaction temperature was 50℃.

[0168] The stirring speed of the reaction process was adjusted to 400 r / min. Metal salt solution (3% / h of reactor volume), sodium hydroxide solution (1.20% / h of reactor volume), and ammonia water (0.12% / h of reactor volume) were introduced at the set flow rates, and the pH value of the reaction process was controlled at 11.10. The reaction continued until a binary high-nickel nickel-cobalt hydroxide precursor precipitate with a particle size D50 of 1.9 μm was obtained. After washing and drying the precipitate, the dried material was sieved to obtain the precursor product, whose chemical composition is Ni. 0.94 Co 0.05 Co 0.01 (OH)2.

[0169] Figure 12 Here is a SEM image of the precursor obtained in Comparative Example 5;

[0170] The precursor material obtained above was mixed with lithium hydroxide in a molar ratio of 1:1.05 and sintered at 660°C for 12 hours to prepare a lithium-ion battery cathode material.

[0171] The physicochemical properties of the precursors obtained in the examples and comparative examples are shown in Table 1:

[0172] Table 1. Physicochemical properties of the precursors obtained from each embodiment and comparative example.

[0173]

[0174] Electrochemical performance was tested using coin cell half-cells: The positive electrode materials prepared in the above examples and comparative examples were mixed with conductive carbon black and PVDF (polyvinylidene fluoride) binder in an 8:1:1 ratio to form a slurry, which was then coated onto aluminum foil to form the positive electrode sheet. A lithium metal sheet was used as the negative electrode sheet, and a 1 mol / L LiPF6 / EC:DMC electrolyte (volume ratio 1:1) was used. The battery casing, positive and negative electrode sheets, separator, spring contacts, and gaskets were assembled into a coin cell in a vacuum glove box. Electrochemical performance was tested using a Blue Electric testing system.

[0175] Compaction density test: The compaction density was tested under a pressure of 3t, and the cross-sectional area of ​​the sample was 1.298 cm². 2 ).

[0176] At room temperature, charge-discharge tests at 0.1C (1C = 210 mA / g) and 50 cycles at 1C were conducted under conditions of 3.0-4.3V. The volumetric energy density was calculated at 0.1C current using the formula: volumetric energy density (Wh / L) = average discharge voltage (V) × discharge capacitance (A / kg) × compaction density (kg / L). The electrochemical performance is shown in Table 2.

[0177] Table 2. Electrochemical performance of the cathode materials obtained from the precursors of each embodiment and comparative example.

[0178]

[0179] The cathode materials prepared in Comparative Examples 1 to 4 lack the structure and physicochemical properties of this application, and therefore cannot simultaneously achieve the desired initial charge-discharge specific capacity, initial coulombic efficiency, and volumetric energy density. Specifically, compared to Example 1, although the precursor of Comparative Example 1 has a TD / D50 > 0.9, its average particle size is greater than 2.0 μm. The cathode material made from it has significantly lower charge-discharge capacity, initial coulombic efficiency, and volumetric energy density than Example 1. Compared to Example 1, the precursor of Comparative Example 2 has a lower tap density, a higher specific surface area, larger pores, and a looser structure. The cathode material made from it has a higher initial charge-discharge capacity than Example 1, but its tap density is lower, and its volumetric energy density is lower than Example 1. Compared to Example 1, the precursors of Comparative Examples 3 and 4 have higher tap densities, but their particle size is significantly larger than that of Example 1, and their TD / D50 ≤ 0.9. Their charge-discharge capacity and initial coulombic efficiency are lower than those of Example 1. Compared with Example 1, Comparative Example 5 has a higher sintering temperature, a lower initial charge-discharge capacity, and a lower volumetric energy density than Example 1.

[0180] As can be seen from Examples 1 to 3, the cathode prepared based on the high tap density small particle size precursor of this application has both high initial charge-discharge specific capacity, high initial coulombic efficiency, high rate performance and high volumetric energy density.

[0181] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0182] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A high tap density, small particle size cathode material precursor, characterized in that, The cathode material precursor satisfies the following conditions: TD / D50 is 0.9-1.3 g / (cm³). 3 •μm), D50≤2.0μm; The chemical formula of the cathode material precursor is Ni. x Co y Mn z M p (OH)2, wherein 0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, 0≤p≤0.05, x+y+z+p=1; M is a dopant element, which includes one or more of W, Zr, Mg, Al, Ti, and Y; The BET of the cathode material precursor is 8-18m. 2 / g.

2. The high tap density, small particle size cathode material precursor according to claim 1, characterized in that, The cathode material precursor satisfies one or more of the following conditions: A. The TD of the cathode material precursor is ≥1.5 g / cm³. 3 ; B. The D90 of the cathode material precursor is 1.0-4.5 μm; C. The D90 / D50 of the cathode material precursor is < 2.5; D. The ratio of (D90-D10) / D50 of the cathode material precursor is 0.3-1.

9.

3. The high tap density, small particle size cathode material precursor according to claim 2, characterized in that, The cathode material precursor satisfies one or more of the following conditions: A. The TD of the cathode material precursor is ≥1.7 g / cm³. 3 ; B. The D90 of the cathode material precursor is 2.0-3.2 μm; C. The D90 / D50 of the cathode material precursor is ≤1.8; D. The ratio of (D90-D10) / D50 of the cathode material precursor is 0.8-1.

2.

4. The high tap density, small particle size cathode material precursor according to claim 1, characterized in that, The cathode material precursor satisfies one or more of the following conditions: (1) The overall porosity of the secondary particles in the cathode material precursor is 5%-30%; (2) The cathode material precursor has a core and a shell covering the core, and the porosity of the core is greater than that of the shell. (3) The secondary particles of the cathode material precursor are composed of elongated primary particles arranged radially thereon; (4) The cathode material precursor has a core and a shell covering the core, the diameter of the core is 0.8-1.5μm and the thickness of the shell is 0.2-0.8μm.

5. The high tap density, small particle size cathode material precursor according to claim 4, characterized in that, The cathode material precursor satisfies one or more of the following conditions: (1) The overall porosity of the secondary particles in the cathode material precursor is 10%-20%; (2) The porosity of the core is 15%-50%; (3) The average length of the primary particles is 200-500 nm.

6. The high tap density, small particle size cathode material precursor according to claim 4, characterized in that, The porosity of the shell is 3%-10%.

7. The high tap density, small particle size cathode material precursor according to claim 4, characterized in that, The porosity difference between the core and the shell is 5%-20%.

8. The high tap density, small particle size cathode material precursor according to claim 4, characterized in that, The average width of the primary particles is 50-150 nm.

9. The high tap density, small particle size cathode material precursor according to claim 4, characterized in that, The average aspect ratio of the primary particles is (2-10):

1.

10. The high tap density, small particle size cathode material precursor according to any one of claims 1-9, characterized in that, The nickel element in the cathode material precursor accounts for more than 80% of the total molar content of metal elements.

11. The high tap density, small particle size cathode material precursor according to claim 10, characterized in that, The nickel element in the cathode material precursor accounts for more than 90% of the total molar content of metal elements.

12. A method for preparing a high-tap-density, small-particle-size cathode material precursor according to any one of claims 1-11, characterized in that, include: A base solution was prepared by precipitating agent and complexing agent. Metal salt solution, precipitating agent and complexing agent were added to the base solution. The pH, ammonia concentration, stirring speed and material flow rate of the system were controlled. The high tap density small particle size cathode material precursor was obtained by co-precipitation method. The co-precipitation method is intermittent; the metal salt solution includes one or more of nickel salt and cobalt salt, manganese salt, and dopant element salt of the corresponding target precursor; the total concentration of metal ions in the metal salt solution is 100-120 g / L; the precipitant includes sodium hydroxide, the complexing agent includes ammonia water, and the mass percentage concentration of the ammonia water is 15%-25%; the pH of the base solution is 11.8-12.3, the pH of the reaction is 11.1-11.5; the ammonia concentration is 3.0-5.8 g / L; the reaction temperature is 40-55℃; the stirring speed is 400-600 rpm; the flow rate of the metal salt solution is 2%-4.5% / h of the reaction vessel volume, the flow rate of the precipitant is 1%-1.5% / h of the reaction vessel volume, and the flow rate of the complexing agent is 0.10%-0.15% / h of the reaction vessel volume.

13. A positive electrode material, characterized in that, It is obtained by sintering a high tap density small particle size cathode material precursor as described in any one of claims 1-11 with a lithium source.

14. A method for preparing the cathode material according to claim 13, characterized in that, include: The high tap density, small particle size cathode material precursor is mixed with a lithium source and sintered to obtain the cathode material.

15. The method for preparing the cathode material according to claim 14, characterized in that, The sintering temperature is 500-650℃ and the time is 10-15h.

16. A lithium-ion battery, characterized in that, Its raw materials include the cathode material as described in claim 13.

17. An electrical-related device, characterized in that, Including the lithium-ion battery as described in claim 16.

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