Cathode material precursor, preparation method thereof, cathode material, secondary battery and electrical equipment

Abstract

The application provides a positive electrode material precursor, a preparation method of the positive electrode material precursor, a positive electrode material, a secondary battery and an electrical equipment. The precursor comprises secondary particles composed of primary particles. The secondary particles comprise A-type particles, B-type particles and C-type particles, all of which have a core-shell structure. The particle size of the A-type particles, the B-type particles and the C-type particles decreases in turn. The thickness ratio t of the outer layer and the inner core of the A-type particles, the B-type particles and the C-type particles decreases in turn. The porosity of the outer layer of the same type of particles in the A-type particles, the B-type particles and the C-type particles is greater than the porosity of the inner core. The precursor provided by the application is beneficial to improving the rate performance of the battery and reducing the cycle resistance.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a cathode material precursor and its preparation method, cathode material, secondary battery and electrical equipment. Background Technology

[0002] As one of the core materials of a battery, the cathode material determines the overall performance of the battery. Medium-to-high nickel ternary cathode materials have advantages such as high specific capacity, low cost, and good compatibility with electrolytes. High-energy-density power lithium-ion batteries made from these materials are widely used in the automotive and other power markets. With the development of electric vehicles, higher requirements are placed on the rate performance and cycle resistance of batteries. Therefore, it is particularly important to develop a cathode material with good rate performance and low cycle resistance. Summary of the Invention

[0003] This application provides a cathode material precursor and its preparation method, a cathode material, a secondary battery, and an electrical device, which at least solve the aforementioned technical problems of existing cathode materials.

[0004] According to a first aspect of the present invention, a cathode material precursor is provided, the cathode material precursor comprising secondary particles composed of primary particles, the secondary particles comprising type A particles, type B particles, and type C particles, all having a core-shell structure; the particle size of type A particles, type B particles, and type C particles decreases sequentially; the thickness ratio t of the outer layer and the core of type A particles, type B particles, and type C particles decreases sequentially; the porosity of the outer layer of the same type of particle among type A particles, type B particles, and type C particles is greater than the porosity of its core.

[0005] The secondary particles (including type A, type B, and type C particles) of the precursor provided in this application have a higher porosity in the outer layer than in the core of the same particle. This results in a structure where the secondary particles have a compact core and a loose outer layer. Furthermore, the ratio of the outer layer thickness to the core thickness of the secondary particles is positively correlated with their particle size. That is, the ratio of the outer layer thickness to the core thickness of the smaller-sized secondary particles (type C particles) is smaller. After preparing the cathode material, this can reduce the side reactions between the cathode material and the electrolyte and improve the stability of the battery. The secondary particles (type A or type B particles) of the precursor have a smaller core thickness ratio. After preparing the cathode material, this can reduce the concentration polarization between the active material inside the cathode material and the outer layer, improve the rate performance of the battery, and reduce the cycle resistance.

[0006] In some embodiments of this application, the particle size d of type A particles is ≥ 5.0 μm, and can be 6.5 μm ≥ d ≥ 5.5 μm; the particle size d of type B particles is 5.0 μm > d ≥ 3.0 μm, and can be 4.5 μm ≥ d ≥ 3.5 μm; the particle size d of type C particles is 3 μm > d ≥ 1 μm, and can be 2.5 μm ≥ d ≥ 1.5 μm.

[0007] Based on the above particle size range, all secondary particles of the cathode material precursor can be divided into three categories (Class A particles, Class B particles, and Class C particles). In some embodiments, "secondary particles include Class A particles, Class B particles, and Class C particles, all of which have a core-shell structure" means that "secondary particles are composed of Class A particles, Class B particles, and Class C particles, all of which have a core-shell structure".

[0008] In some embodiments of this application, the thickness of the outer layer and the core of the type A particle is greater than t. A ≥2.0, optional 3.0≥t A ≥2.0.

[0009] In some embodiments of this application, the thickness of the outer layer and the core of the type B particle is greater than t. B Satisfy: 2.0 > t B ≥1.2, optional 1.9≥t B ≥1.3.

[0010] In some embodiments of this application, the thickness of the outer layer and the core of the C-type particle is greater than t. C Satisfies the condition that 1.2 > t C ≥0.3, optional 1.19≥t C ≥0.5.

[0011] In some embodiments of this application, the thickness ratio distribution of the type A particles, type B particles, and type C particles is span = (t A -t C ) / t B For values ​​above 0.1, a range of 0.4-1.5 is acceptable; where t A It is the ratio of the thickness of the outer layer to the thickness of the core of a type A particle, t B It is the ratio of the outer layer to the core thickness of a type B particle, t C It is the ratio of the thickness of the outer layer to the thickness of the core of a Class C particle.

[0012] In some embodiments of this application, the thickness ratio of the cores of the A-type particles, B-type particles, and C-type particles is 1:0.8~1.2:0.8~1.2.

[0013] In some embodiments of this application, the average number of primary lamellae of Class A particles, Class B particles, and Class C particles decreases sequentially.

[0014] In some embodiments of this application, the average thickness of the primary particles of type A particles, type B particles, and type C particles decreases sequentially. Optionally, the average thickness of the primary particles of type A particles is 10–160 nm, preferably 30–70 nm; optionally, the average thickness of the primary particles of type B particles is 10–130 nm, preferably 30–70 nm; optionally, the average thickness of the primary particles of type C particles is 2–100 nm, preferably 4–30 nm.

[0015] In some embodiments of this application, the average length-to-thickness ratio of the primary particles of type A particles, type B particles, and type C particles increases sequentially. Optionally, the average length-to-thickness ratio of the primary particles of type A particles is 5-60, preferably 10-30; optionally, the average length-to-thickness ratio of the primary particles of type B particles is 10-60, preferably 15-30; optionally, the average length-to-thickness ratio of the primary particles of type C particles is 5-60, preferably 20-30.

[0016] In some embodiments of this application, the overall porosity of type A particles, type B particles, and type C particles increases sequentially. Optionally, the overall porosity of type A particles is 10%–30%, preferably 12%–25%; optionally, the overall porosity of type B particles is 10%–30%, preferably 12%–25%; optionally, the overall porosity of type C particles is 10%–40%, preferably 20%–35%.

[0017] In some embodiments of this application, the core porosity of the type A particles is 2%-10%, and the porosity of the outer layer is 10%-30%.

[0018] In some embodiments of this application, the core porosity of the B-type particles is 2%-10%, and the outer porosity is 10%-30%.

[0019] In some embodiments of this application, the core porosity of the C-type particles is 2%-10%, and the porosity of the outer layer is 10%-40%.

[0020] In some embodiments of this application, the average particle size D50 of the cathode material precursor is 2 to 15 μm, and can be selected as 3.0-5.0 μm.

[0021] In some embodiments of this application, the span value of the particle size distribution of the cathode material precursor is...

[0022] = (D95-D10) / D50 is 0.7~1.3, and can be selected from 0.8 to 1.2.

[0023] In some embodiments of this application, the sphericity R of the cathode material precursor q The range is 70% to 100%, with 90% to 100% being optional.

[0024] In some embodiments of the present application, the specific surface area BET of the cathode material precursor is 5-18 m 2 / g, preferably 12-15 m 2 / g.

[0025] In some embodiments of the present application, the tap density TD of the cathode material precursor is 1.2-3.0 g / cm 3 ³, preferably 1.4-2.4 g / cm 3 ³.

[0026] In some embodiments of the present application, the full width at half maximum FWHM(001) of the X-ray diffraction test of the cathode material precursor is 0.210-0.550°, preferably 0.230-0.500°, and FWHM(101) is 0.210-0.550°, preferably 0.230-0.500°.

[0027] In some embodiments of the present application, the peak intensity ratio I(101) / I(001) of the X-ray diffraction test of the cathode material precursor is 1.00-1.50, preferably 1.01-1.40.

[0028] In some embodiments of the present application, the ratio of the grain size of the (101) crystal plane to the (001) crystal plane D(101) / D(001) in the X-ray diffraction test of the cathode material precursor is 2.0-2.5, preferably 2.0-2.4.

[0029] In some embodiments of the present application, the thickness of the outer layer of the secondary particles is 0.3-10 μm, preferably 0.5-8 μm, and the thickness of the inner core of the secondary particles is 0.3-2.0 μm, preferably 0.4-1.8 μm.

[0030] In some embodiments of the present application, the chemical formula of the cathode material precursor is (Ni[[ID=#27]] x Co y Mn[[ID=3#1]] 1-x-y-z M z )(OH)₂) material, where 0.5 ≤ x < 1, 0 < y ≤ 0.5, 0 ≤ z < 0.5, x + y + z ≤ 1), and the doping element M is at least one or more of Ti, Mg, Zn, Cu, Al, Ga, In, La, Cr, Si, Sn, W.

[0031] According to the second aspect of the present invention, there is provided a method for preparing the above-mentioned cathode material precursor, comprising:

[0032] The step of synthesizing seeds: simultaneously introducing a metal salt solution, a precipitant solution and a complexing agent solution into a reaction vessel containing a bottom liquid for synthesizing seeds for reaction to obtain a seed slurry;

[0033] In the growth process, the seed slurry is passed sequentially through at least two growth reaction vessels containing growth substrate solutions, and a synthesis reaction is carried out in each growth reaction vessel using a metal salt solution, a precipitant solution, and a complexing agent solution that are simultaneously introduced, to obtain the cathode material precursor.

[0034] The pH of the synthetic seed solution is higher than that of the growth solution, and the concentration of the complexing agent in the synthetic seed solution is lower than that in the growth solution.

[0035] In some embodiments of this application, the metal salt includes a first metal salt, which includes one or more combinations of nickel salt, cobalt salt, manganese salt, and doped element salts, including at least nickel salt. Optionally, the sum of the mass concentrations of metal ions in the first metal salt solution is 50-160 g / L, and optionally 60-150 g / L.

[0036] In some embodiments of this application, the metal salt includes a first metal salt and a second metal salt. The first metal salt includes one or more combinations of nickel salt, cobalt salt, manganese salt, and dopant element salts, including at least nickel salt. Optionally, the sum of the mass concentrations of metal ions in the first metal salt solution is 50-160 g / L, optionally 60-150 g / L. The second metal salt includes one or more combinations of dopant element salts. Optionally, the sum of the mass concentrations of metal ions in the second metal salt solution is 0.1-2.0 g / L, optionally 0.5-1.5 g / L.

[0037] In some embodiments of this application, the precipitant includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. Optionally, the mass percentage concentration of the precipitant solution is 20.0%-40.0%, preferably 25.0%-35.0%.

[0038] In some embodiments of this application, the complexing agent includes one or more of citric acid, ammonium citrate, oxalic acid, ammonium oxalate, ammonia, and ammonium carbonate. Optionally, the mass percentage concentration of the complexing agent solution is 10.1% to 30.5%, and optionally 15.0% to 25.0%.

[0039] In some embodiments of this application, the pH of the seed crystal substrate is maintained at 10.00–13.00, optionally 10.5–12.50; the concentration of the complexing agent in the seed crystal substrate is maintained at 0.5–5.0 g / L, optionally 1.5–3.5 g / L.

[0040] In some embodiments of this application, the temperature of the seed crystal substrate is maintained at 40-80°C, optionally 55-70°C; the stirring speed of the seed crystal substrate is 200-500 r / min, optionally 250-450 r / min.

[0041] In some embodiments of this application, the pH of the growth substrate is maintained at 10.00–13.00, preferably 10.5–12.50; the concentration of the complexing agent in the growth substrate is maintained at 1.0–6.0 g / L, preferably 2.5–4.5 g / L.

[0042] In some embodiments of this application, the temperature of the growth substrate is maintained at 40-80°C, optionally 55-70°C; the stirring speed of the growth substrate is 200-500 r / min, optionally 250-450 r / min.

[0043] In some embodiments of this application, in the seed crystal synthesis process, the metal salt solution includes a first metal salt solution, the inflow rate of which is 2.0–6.0% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 2.5–4.5% / h; the inflow rate of the precipitant solution is 0.5–2% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 1.0–1.8% / h; and the inflow rate of the complexing agent solution is 0.01–0.50% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 0.01–0.10% / h.

[0044] In some embodiments of this application, in the seed crystal synthesis process, the metal salt solution includes a first metal salt solution and a second metal salt solution. The inflow rate of the first metal salt solution is 2.0–6.0% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 2.5–4.5% / h. The inflow rate of the second metal salt solution is 40%–80% of the inflow rate of the first metal salt solution. The inflow rate of the precipitant solution is 0.5–2% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 1.0–1.8% / h. The inflow rate of the complexing agent solution is 0.01–0.50% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 0.01–0.10% / h.

[0045] In some embodiments of this application, during the growth process, the metal salt solution includes a first metal salt solution, the first metal salt solution being introduced at a rate of 5.0–10.0% / h of the available volume of the growth reaction vessel, optionally 7.0–9.0% / h; the precipitant solution being introduced at a rate of 1.0–5.0% / h of the available volume of the growth reaction vessel, optionally 2.5–4.0% / h; and the complexing agent solution being introduced at a rate of 0.01–3.50% / h of the available volume of the growth reaction vessel, optionally 0.01–0.10% / h.

[0046] In some embodiments of this application, in the growth process, the metal salt solution includes a first metal salt solution and a second metal salt solution. The inflow rate of the first metal salt solution is 5.0–10.0% / h of the available volume of the seed crystal reaction vessel, optionally 7.0–9.0% / h. The inflow rate of the second metal salt solution is 40%–80% of the inflow rate of the first metal salt solution. The inflow rate of the precipitant solution is 1.0–5.0% / h of the available volume of the growth reaction vessel, optionally 2.5–4% / h. The inflow rate of the complexing agent solution is 0.01–3.50% / h of the available volume of the growth reaction vessel, optionally 0.01–0.10% / h.

[0047] According to a third aspect of the present invention, a positive electrode material is provided, the raw material of which includes the above-described positive electrode material precursor.

[0048] According to a fourth aspect of the present invention, a secondary battery is provided, comprising a positive electrode sheet comprising the aforementioned positive electrode material.

[0049] According to a fifth aspect of the present invention, an electrical device is provided, comprising the aforementioned secondary battery. Attached Figure Description

[0050] To more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 SEM image (10 μm scale bar) of the cathode material precursor prepared in Example 1;

[0052] Figure 2 SEM image (3 μm scale bar) of type A particles prepared in Example 1;

[0053] Figure 3 SEM image (1 μm scale bar) of type A particles prepared in Example 1;

[0054] Figure 4 SEM image (2μm scale bar) of type B particles prepared in Example 1;

[0055] Figure 5 SEM image (1 μm scale bar) of type B particles prepared in Example 1;

[0056] Figure 6 SEM image (1 μm scale bar) of the C-type particles prepared in Example 1;

[0057] Figure 7 SEM image (500 nm scale bar) of the C-type particles prepared in Example 1;

[0058] Figure 8 CP cross-sectional view (3μm scale bar) of the type A particles prepared in Example 1;

[0059] Figure 9 CP cross-sectional view (2μm scale bar) of type B particles prepared in Example 1;

[0060] Figure 10 CP cross-sectional view (1 μm scale bar) of the C-type particles prepared in Example 1. Detailed Implementation

[0061] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0062] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0063] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0064] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, optionally sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0065] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" may also include or contain other components not listed, or may include only or contain the listed components.

[0066] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0067] This application provides a cathode material precursor, which includes secondary particles composed of primary particles. The secondary particles include type A particles, type B particles, and type C particles with core-shell structures. The particle size of type A particles, type B particles, and type C particles decreases sequentially. The thickness ratio t of the outer layer and the core of type A particles, type B particles, and type C particles decreases sequentially. The porosity of the outer layer of the same type of particle among type A particles, type B particles, and type C particles is greater than the porosity of its core.

[0068] Since the prepared cathode material partially inherits the morphology, structure, and physicochemical properties of the precursor, this application improves the rate performance and cycle performance of the cathode material by designing the precursor structure and morphology. The secondary particles (including type A, type B, and type C particles) of the precursor provided in this application have a higher porosity in the outer layer than in the core, resulting in a structure where the secondary particles have a compact core and a loose outer layer. Furthermore, the ratio of the outer layer thickness to the core thickness of the secondary particles is positively correlated with their particle size; that is, smaller-sized secondary particles (type C particles) have a smaller ratio of outer layer to core thickness. After preparing the cathode material, this reduces side reactions between the cathode material and the electrolyte, improving battery stability. Larger-sized precursor secondary particles (type A or type B particles) have a smaller core thickness ratio. After preparing the cathode material, this reduces concentration polarization between the active material inside the cathode material and the outer layer, improving the battery's rate performance and reducing cycle resistance.

[0069] In some embodiments of this application, the particle size d of type A particles is ≥ 5.0 μm, and can be 6.5 μm ≥ d ≥ 5.5 μm, such as 5.8 μm, 6.1 μm, 6.4 μm, etc.; the particle size d of type B particles is 5.0 μm > d ≥ 3.0 μm, and can be 4.5 μm ≥ d ≥ 3.5 μm, such as 3.8 μm, 4.0 μm, 4.2 μm, etc.; the particle size d of type C particles is 3 μm > d ≥ 1 μm, and can be 2.5 μm ≥ d ≥ 1.5 μm, such as 1.7 μm, 2.1 μm, 2.4 μm, etc. The particle size of type A, type B, and type C particles forms a gradient structure, which is beneficial to increasing the compaction density of the cathode material after preparation, thereby improving the stability and rate performance of the battery.

[0070] In some embodiments of this application, the thickness of the outer layer and the core of the type A particle is greater than t. A ≥2.0, optional 3.0≥t A ≥2.0, such as 2.1, 2.3, 2.5, 2.8, etc.

[0071] In some embodiments of this application, the thickness of the outer layer and the core of the type B particle is greater than t. B Satisfy: 2.0 > t B ≥1.2, optional 1.9≥t B ≥1.3, such as 1.45, 1.5, 1.65, 1.8, etc.

[0072] In some embodiments of this application, the thickness of the outer layer and the core of the C-type particle is greater than t. C Satisfies the condition that 1.2 > t C ≥0.3, optional 1.19≥t C ≥0.5, such as 0.65, 0.8, 0.95, 1.0, 1.05, etc.

[0073] In some embodiments of this application, the thickness ratio distribution of the type A particles, type B particles, and type C particles is span = (t A -t C ) / t B For values ​​above 0.1, a range of 0.4-1.5 is acceptable; where t A It is the ratio of the thickness of the outer layer to the thickness of the core of a type A particle, t B It is the ratio of the outer layer to the core thickness of a type B particle, t C This refers to the thickness ratio of the outer layer to the core of the C-type particles. It indicates that the thickness ratio of the outer layer to the core of the secondary particles is relatively wide. As the number of secondary particles increases, the proportion of the core in the entire secondary particle gradually decreases, which is beneficial for ensuring battery stability and rate performance.

[0074] In some embodiments of this application, the thickness ratio of the cores of the A-type particles, B-type particles, and C-type particles is 1:0.8 to 1.2:0.8 to 1.2, and can be 1:1:1.

[0075] In some embodiments of this application, type A particles, type B particles, and type C particles have at least one of the following properties: the average number of lamellae in the primary particles of type A, type B, and type C particles decreases sequentially; the average thickness of the primary particles of type A, type B, and type C particles decreases sequentially; the average aspect ratio of the primary particles of type A, type B, and type C particles increases sequentially; and the overall porosity of type A, type B, and type C particles increases sequentially.

[0076] Specifically, during the sintering process of the precursor in the preparation of cathode materials, if the particle size of the precursor is smaller, the heat transfer capacity is stronger. After sintering, the primary particles on the surface of the precursor are prone to rapid agglomeration to form larger primary particles, resulting in uneven sintering of primary particles between large and small particles. That is, the difference in primary particles on the surface of the cathode material is large, thus affecting the electrochemical performance of the cathode material. The cathode material precursor provided in this application has at least one of the above properties, such as the average thickness of the primary particles and the average number of lamellar layers of the primary particles decreasing sequentially, or the porosity of the secondary particles and the average length-to-thickness ratio of the primary particles increasing sequentially. That is, when the primary particles of small particles are fine, have fewer average lamellar layers, or have high porosity, and the primary particles of large particles are coarse, have more average lamellar layers, or have lower porosity, the problem of uneven primary particles on the surface of large and small particles during sintering can be alleviated, making the primary particles on the surface of the cathode material more uniform. This can alleviate overcharging and over-discharging in local areas during the charge and discharge process of the cathode material prepared by it, and improve the cycle performance and rate performance of the cathode material.

[0077] In the embodiments of this application, the average thickness of the primary particles of type A particles is 10–160 nm, optionally 30–70 nm, such as 35 nm, 42 nm, 51 nm, 58 nm, 64 nm, etc. In the embodiments of this application, the average thickness of the primary particles of type B particles is 10–130 nm, optionally 30–70 nm, such as 28 nm, 33 nm, 39 nm, 45 nm, etc. In the embodiments of this application, the average thickness of the primary particles of type C particles is 2–100 nm, optionally 4–30 nm, such as 4 nm, 7 nm, 11 nm, 15 nm, etc.

[0078] Optionally, the average length-to-thickness ratio of the primary particles of type A particles is 5 to 60, and can be selected from 10 to 30, such as 13, 15, 16, etc.; Optionally, the average length-to-thickness ratio of the primary particles of type B particles is 10 to 60, and can be selected from 15 to 30, such as 20, 24, 26, etc.; Optionally, the average length-to-thickness ratio of the primary particles of type C particles is 5 to 60, and can be selected from 20 to 30, such as 25, 29, 32, etc.

[0079] Optionally, the overall porosity of type A particles is 10% to 30%, and can be selected from 12% to 25%, such as 13%, 15%, 17%, etc.; Optionally, the overall porosity of type B particles is 10% to 30%, and can be selected from 12% to 25%, such as 13%, 15%, 17%, etc.; Optionally, the overall porosity of type C particles is 10% to 40%, and can be selected from 20% to 35%, such as 22%, 25%, 27%, 28%, etc.

[0080] In some embodiments of this application, the core porosity of the type A particles is 2%-10%, and the porosity of the outer layer is 10%-30%.

[0081] In some embodiments of this application, the core porosity of the B-type particles is 2%-10%, and the outer porosity is 10%-30%.

[0082] In some embodiments of this application, the core porosity of the C-type particles is 2%-10%, and the porosity of the outer layer is 10%-40%.

[0083] In some embodiments of this application, the average particle size D50 of the cathode material precursor is 2–15 μm, optionally 3.0–5.0 μm, such as 3.2 μm, 3.8 μm, 4.3 μm, 4.7 μm, etc. The smaller particle size of the secondary particles is beneficial for maximizing the activity of the internal substances in the cathode material prepared from them, thereby improving its capacity performance.

[0084] In the embodiments of this application, the span value of the particle size distribution of the cathode material precursor, ((D95-D10) / D50), is 0.7 to 1.3, and can be selected from 0.8 to 1.2, such as 0.87, 0.91, 0.95, 0.99, 1.02, etc. This indicates that the secondary particles have a wider particle size distribution, which is beneficial to improving the compaction density of the cathode material prepared from it, thereby improving the energy density of the battery.

[0085] In some embodiments of this application, the sphericity R of the secondary particles q The sphericity ranges from 70% to 100%, with options including 94%, 95%, 97%, and 99%. Excellent sphericity is beneficial for increasing the filling density of the cathode material prepared from it, improving the energy density of the battery, enhancing the compressive strength of the cathode material during charge and discharge, and improving the rate performance of the cathode material.

[0086] In some embodiments of this application, the specific surface area (BET) of the cathode material precursor is 5–18 m². 2 / g, 12-15m can be selected 2 / g, such as 12.5m 2 / g、13m 2 / g, 13.5m 2 / g、14m 2 / g. This indicates that the secondary particles have a more porous structure, which is beneficial for the full wetting of the positive electrode material prepared by the electrolyte in the battery, improves the diffusion ability of the electrolyte, promotes the rapid transport of electrons and lithium ions, and can effectively improve the charge and discharge performance of the battery.

[0087] In some embodiments of this application, the tap density (TD) of the cathode material precursor is 1.2–3.0 g / cm³. 3 1.4–2.4 g / cm³ is available. 3 For example, 1.63 g / cm³ 3 1.71 g / cm 3 1.78g / cm 3 1.85g / cm 3 1.92g / cm 3 wait.

[0088] In some embodiments of this application, the full width at half maximum (FWHM) of the X-ray diffraction precursor is 0.210–0.550°, optionally 0.230–0.500°, and the FWHM (101) is 0.210–0.550°, optionally 0.230–0.500°, such as 0.250°, 0.290°, 0.360°, 0.440°, etc. The smaller FWHM of the secondary particles indicates higher crystallinity, which is beneficial for improving the cycling performance of the material.

[0089] In some embodiments of the present application, the peak intensity ratio I(101) / I(001) of the X-ray diffraction test of the cathode material precursor is 1.00 to 1.50, optionally 1.01 to 1.40, such as 1.05, 1.12, 1.19, 1.26, 1.31, 1.37, etc. The secondary particles have a relatively high peak intensity ratio, indicating that the cathode material precursor has a relatively high crystallinity, making the cathode material prepared therefrom more stable during charge and discharge, which is beneficial to improving the cycle performance of the cathode material and extending the service life of the battery.

[0090] In a further embodiment, the ratio D(101) / D(001) of the grain sizes of the (101) crystal plane and the (001) crystal plane in the X-ray diffraction test of the cathode material precursor is 2.0 to 2.5, optionally 2.0 to 2.4, such as 2.1, 2.2, 2.3, etc. The relatively large D value of the secondary particles is beneficial to improving the cycle stability performance of the cathode material.

[0091] In some embodiments of the present application, the chemical formula of the cathode material precursor is (Ni x Co y Mn 1-x-y-z M z )(OH)2) material, where 0.5 ≤ x < 1, 0 < y ≤ 0.5, 0 ≤ z < 0.5, x + y + z ≤ 1), and the doping element M is at least one or more of Ti, Mg, Zn, Cu, Al, Ga, In, La, Cr, Si, Sn, W. Multiple elements can be doped to improve the electrochemical performance of the cathode material prepared therefrom.

[0092] The present application provides a preparation method of the above-mentioned cathode material precursor, including:

[0093] The step of synthesizing seed crystals: simultaneously introducing a metal salt solution, a precipitant solution, and a complexing agent solution into a reaction vessel containing a bottom solution for synthesizing seed crystals to react, and obtaining a seed crystal slurry;

[0094] The growth step: the seed crystal slurry sequentially passes through at least 2 growth reaction vessels containing a growth bottom solution, and after performing a synthesis reaction in each growth reaction vessel by simultaneously introducing a metal salt solution, a precipitant solution, and a complexing agent solution, a cathode material precursor is obtained;

[0095] The pH of the bottom solution for synthesizing seed crystals is higher than the pH of the growth bottom solution, and the concentration of the complexing agent in the bottom solution for synthesizing seed crystals is lower than the concentration of the complexing agent in the growth bottom solution.

[0096] In some embodiments of the present application, the metal salt includes a first metal salt, and the first metal salt is one or more combinations including at least a nickel salt among nickel salts, cobalt salts, manganese salts, and doping element salts.

[0097] The multiple combinations of at least nickel salts should be understood as including nickel salts and at least one of cobalt salts, manganese salts and doped metal salts; wherein, nickel salts include one or more of nickel sulfate, nickel nitrate, and nickel chloride; cobalt salts include one or more of cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt carbonate; manganese salts include one or more of manganese sulfate, manganese nitrate, manganese chloride, and manganese carbonate; and doped metal salts include one or more of the sulfate, nitrate, hydrochloride, and carbonate of the corresponding doped metal.

[0098] In some embodiments of this application, controlling the sum of the mass concentrations of metal ions in the metal salt solution, the concentration of the precipitant, and the concentration of the complexing agent within a certain range is beneficial for controlling the synthesis reaction.

[0099] The sum of the mass concentrations of metal ions in the first metal salt solution is 50-160 g / L, preferably 60-150 g / L, and further preferably 80-130 g / L, such as 85 g / L, 90 g / L, 94 g / L, 102 g / L, 116 g / L, etc.

[0100] In some embodiments of this application, the metal salt includes a first metal salt and a second metal salt. The first metal salt includes one or more combinations of nickel salt, cobalt salt, manganese salt, and dopant element salts, including at least nickel salt. Optionally, the sum of the mass concentrations of metal ions in the first metal salt solution is 50-160 g / L, optionally 60-150 g / L. The second metal salt includes one or more combinations of dopant element salts. Optionally, the sum of the mass concentrations of metal ions in the second metal salt solution is 0.1-2.0 g / L, optionally 0.5-1.5 g / L.

[0101] The precipitant includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. The mass percentage concentration of the precipitant solution is 20.0%-40.0%, and can be selected from 25.0% to 35.0%, such as 25.2%, 28.1%, 30.4%, 33.8%, 34.5%, etc.

[0102] Complexing agents include one or more of citric acid, ammonium citrate, oxalic acid, ammonium oxalate, ammonia, and ammonium carbonate. The mass percentage concentration of the complexing agent solution is 10.10% to 30.5%, and can be selected from 15.0% to 25.0%, such as 16.2%, 18.5%, 21.3%, 22.6%, 24.4%, etc.

[0103] The pH value of the substrate (synthetic seed substrate or growth substrate) and the concentration of the complexing agent are key parameters affecting the morphology (such as sphericity) and specific surface area (such as porosity) of the precursor. Therefore, when the pH of the synthetic seed substrate is higher than that of the growth substrate and the concentration of the complexing agent in the synthetic seed substrate is lower than that in the growth substrate, secondary particles with a compact core, a loose outer core, and a gradient particle size, as provided in this application, can be prepared by multiple growth processes and by controlling the flow rate of each solution in the growth process.

[0104] Specifically, the pH of the seed crystal substrate is maintained between 10.00 and 13.00, and can be selected between 10.5 and 12.50, such as 10.7, 11.3, 11.9, 12.2, etc.; the concentration of the complexing agent in the seed crystal substrate is maintained between 0.5 and 5.0 g / L, and can be selected between 1.5 and 3.5 g / L, such as 1.6 g / L, 1.8 g / L, 2.2 g / L, 2.4 g / L, etc.

[0105] Optionally, the temperature of the seed crystal substrate is maintained at 40-80℃, preferably 55-70℃, such as 58℃, 62℃, 65℃, 69℃, etc. The stirring speed of the seed crystal substrate is 200-500 r / min, preferably 250-450 r / min, such as 280 r / min, 340 r / min, 380 r / min, 420 r / min, etc.

[0106] Optionally, the pH of the growth substrate is maintained at 10.00–13.00, preferably 10.5–12.50, such as 10.7, 11.3, 11.8, 12.1, 12.4, etc.; the concentration of the complexing agent in the growth substrate is maintained at 1.0–6.0 g / L, preferably 2.5–4.5 g / L, such as 2.6 g / L, 2.9 g / L, 3.3 g / L, 3.8 g / L, 4.2 g / L, etc.

[0107] Optionally, the temperature of the growth solution is maintained at 40-80℃, preferably 55-70℃, such as 58℃, 63℃, 69℃, 74℃, or 79℃. The stirring speed of the growth solution is 200-500 r / min, preferably 250-450 r / min, such as 280 r / min, 340 r / min, 380 r / min, or 420 r / min.

[0108] Optionally, in the seed crystal synthesis process, the metal salt solution includes a first metal salt solution, the inflow rate of which is 2.0–6.0% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 2.5–4.5% / h, such as 2.8% / h, 3.4% / h, 3.9% / h, 4.3% / h, etc.; the inflow rate of the precipitant solution is 0.5–2% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 1.0–1.8% / h, such as 1.1% / h, 1.2% / h, 1.4% / h, 1.6% / h, etc.; the inflow rate of the complexing agent solution is 0.01–0.50% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 0.01–0.10% / h, such as 0.02% / h, 0.05% / h, 0.07% / h, 0.09% / h, etc.

[0109] Optionally, in the seed crystal synthesis process, the metal salt solution includes a first metal salt solution and a second metal salt solution. The introduction rate of the first metal salt solution is 2.0–6.0% / h of the available volume of the seed crystal synthesis reaction vessel, optionally 2.5–4.5% / h, such as 2.8% / h, 3.4% / h, 3.9% / h, 4.3% / h, etc. The introduction rate of the second metal salt solution is 40%–80% of the introduction rate of the first metal salt solution; the precipitant solution… The influent rate is 0.5–2% / h of the available volume of the seed crystal reaction vessel, and can be selected from 1.0–1.8% / h, such as 1.1% / h, 1.2% / h, 1.4% / h, 1.6% / h, etc.; the influent rate of the complexing agent solution is 0.01–0.50% / h of the available volume of the seed crystal reaction vessel, and can be selected from 0.01–0.10% / h, such as 0.02% / h, 0.05% / h, 0.07% / h, 0.09% / h, etc.

[0110] Optionally, in the growth process, the metal salt solution includes a first metal salt solution, the first metal salt solution being introduced at a rate of 5.0–10.0% / h of the available volume of the growth reaction vessel, optionally 7.0–9.0% / h, such as 7.2% / h, 7.6% / h, 8.1% / h, 8.5% / h, etc.; the precipitant solution being introduced at a rate of 1.0–5.0% / h of the available volume of the growth reaction vessel, optionally 2.5–4.0% / h, such as 2.7% / h, 3.1% / h, 3.5% / h, 3.8% / h, etc.; and the complexing agent solution being introduced at a rate of 0.01–3.50% / h of the available volume of the growth reaction vessel, optionally 0.01–0.10% / h, such as 0.04% / h, 0.06% / h, 0.08% / h, 0.09% / h, etc.

[0111] In some embodiments of this application, in the growth process, the metal salt solution includes a first metal salt solution and a second metal salt solution. The inflow rate of the first metal salt solution is 5.0–10.0% / h of the available volume of the seed crystal reaction vessel, optionally 7.0–9.0% / h, such as 7.2% / h, 7.6% / h, 8.1% / h, 8.5% / h, etc.; the inflow rate of the second metal salt solution is 40%–80% of the inflow rate of the first metal salt solution. The precipitant solution is introduced at a rate of 1.0–5.0% / h of the available volume of the growth reaction vessel, and can be selected from 2.5–4.0% / h, such as 2.7% / h, 3.1% / h, 3.5% / h, 3.8% / h, etc.; the complexing agent solution is introduced at a rate of 0.01–3.50% / h of the available volume of the growth reaction vessel, and can be selected from 0.01–0.10% / h, such as 0.04% / h, 0.06% / h, 0.08% / h, 0.09% / h, etc.

[0112] This application provides a cathode material, the raw materials of which include the aforementioned cathode material precursor. Specifically, the cathode material precursor and a lithium source are used as raw materials, and the mixture is prepared by mixing and sintering.

[0113] This application provides a secondary battery, including a positive electrode sheet, which includes the aforementioned positive electrode material.

[0114] This application provides an electrical device, including the aforementioned secondary battery.

[0115] To fully demonstrate the advantages of the precursor provided in this application, the following description is provided in conjunction with specific embodiments.

[0116] Example 1

[0117] (1) Preparation of cathode material precursor

[0118] 1) Prepare a metal salt solution with a mass concentration of 120 g / L as solution A, wherein the metal salts are nickel sulfate, cobalt sulfate and manganese sulfate, and the molar ratio of nickel, cobalt and manganese is Ni:Co:Mn=96:03:01; prepare a sodium hydroxide solution with a mass percentage concentration of 32% as solution B; and prepare an ammonia solution with a mass percentage concentration of 21% as solution C.

[0119] 2) Add pure water, solution B and solution C to the seed crystal synthesis reactor to prepare the base solution. Control the pH value of the base solution to 11.7 and the mass concentration of ammonia water to 2.0 g / L. Introduce nitrogen gas as a protective gas.

[0120] Add pure water, solution B and solution C to the growth reactor to prepare the base solution. Control the pH value of the base solution to 11.25 and the mass concentration of ammonia water to 3.0 g / L. Introduce nitrogen gas as a protective gas.

[0121] 3) Solutions A, B, and C are simultaneously introduced into the seed crystal synthesis reactor. The flow rates of solutions A, B, and C are 4.00% h, 1.52% h, and 0.03% h of the available volume of the reactor, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.70, the ammonia concentration is maintained at 2.0 g / L, the reaction temperature is maintained at 60℃, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the seed crystal synthesis reactor reaches the overflow position, the overflow feed to the first growth reaction device begins.

[0122] 4) After the seed crystal synthesis reactor begins to overflow into the first growth reactor, solutions A, B, and C are simultaneously introduced into the first growth reactor. The flow rates of solutions A, B, and C are 8.00% / h, 3.04% / h, and 0.06% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.20, the temperature is maintained at 60℃, and the ammonia concentration is maintained at 3.0 g / L. The stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the first growth reactor reaches the overflow position, overflow into the second growth reactor begins.

[0123] After the first growth reactor begins overflowing into the second growth reactor, solutions A, B, and C are simultaneously introduced into the second growth reactor. The flow rates of solutions A, B, and C are 8.00% / h, 3.04% / h, and 0.06% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.20, the temperature is maintained at 60℃, the ammonia concentration is maintained at 3.0 g / L, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the second growth reactor reaches the overflow position, overflowing into the third growth reactor begins.

[0124] After the second growth reactor begins overflowing into the third growth reactor, solutions A, B, and C are simultaneously introduced into the first growth reactor. The flow rates of solutions A, B, and C are 8.00% / h, 3.04% / h, and 0.06% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.20, the temperature is maintained at 60℃, the ammonia concentration is maintained at 3.0 g / L, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the third growth reactor reaches the overflow position, the overflow yields the slurry of the cathode material precursor.

[0125] The reaction was stopped after the average particle size of the secondary particles in the slurry reached 3.5 μm. The resulting slurry was washed, centrifuged, dried, and demagnetized by sieving to obtain a product with the chemical formula Ni. 0.96 Co 0.03 Mn 0.01 (OH)2 cathode material precursor.

[0126] (2) Preparation of cathode materials

[0127] The obtained cathode material precursor was mixed with lithium hydroxide at a ratio of 1:1.05 and sintered at 580℃ for 12 hours to obtain the cathode material.

[0128] Example 2

[0129] (1) Preparation of cathode material precursor

[0130] 1) Prepare a metal salt solution with a mass concentration of 110 g / L as solution A, wherein the metal salts are nickel sulfate, cobalt sulfate and manganese sulfate, and the molar ratio of nickel, cobalt and manganese is Ni:Co:Mn = 96:03:01; prepare a sodium hydroxide solution with a mass percentage concentration of 32% as solution B; and prepare an ammonia solution with a mass percentage concentration of 21% as solution C.

[0131] 2) Add pure water, solution B and solution C to the seed crystal synthesis reactor to prepare the base solution. Control the pH value of the base solution to 11.8 and the mass concentration of ammonia water to 3.0 g / L. Introduce nitrogen gas as a protective gas.

[0132] Add pure water, solution B and solution C to the growth reactor to prepare the base solution. Control the pH value of the base solution to 11.35 and the mass concentration of ammonia water to 4.0 g / L. Introduce nitrogen gas as a protective gas.

[0133] 3) Solutions A, B, and C are simultaneously introduced into the seed crystal synthesis reactor. The flow rates of solutions A, B, and C are 4.00% h, 1.60% / h, and 0.04% / h of the available volume of the reactor, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.80, the ammonia concentration is maintained at 3.0 g / L, the reaction temperature is maintained at 65℃, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the seed crystal synthesis reactor reaches the overflow position, the overflow feed to the first growth reaction device begins.

[0134] 4) After the seed crystal synthesis reactor begins to overflow into the first growth reactor, solutions A, B, and C are simultaneously introduced into the first growth reactor. The flow rates of solutions A, B, and C are 8.00% / h, 3.14% / h, and 0.07% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.35, the temperature is maintained at 65℃, and the ammonia concentration is maintained at 4.0 g / L. The stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the first growth reactor reaches the overflow position, overflow into the second growth reactor begins.

[0135] After the first growth reactor begins overflowing into the second growth reactor, solutions A, B, and C are simultaneously introduced into the second growth reactor. The flow rates of solutions A, B, and C are 8.00% / h, 3.14% / h, and 0.07% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.35, the temperature is maintained at 65℃, the ammonia concentration is maintained at 4.0 g / L, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the second growth reactor reaches the overflow position, overflowing into the third growth reactor begins.

[0136] After the second growth reactor begins overflowing into the third growth reactor, solutions A, B, and C are simultaneously introduced into the first growth reactor. The flow rates of solutions A, B, and C are 8.00% / h, 3.14% / h, and 0.07% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.35, the temperature is maintained at 65℃, the ammonia concentration is maintained at 4.0 g / L, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the third growth reactor reaches the overflow position, the overflow yields the slurry of the cathode material precursor.

[0137] The reaction was stopped after the average particle size of the secondary particles in the slurry reached 3.5 μm. The resulting slurry was washed, centrifuged, dried, and demagnetized by sieving to obtain a product with the chemical formula Ni. 0.96 Co 0.03 Mn 0.01 (OH)2 cathode material precursor.

[0138] (2) Preparation of cathode materials

[0139] The obtained cathode material precursor was mixed with lithium hydroxide at a ratio of 1:1.05 and sintered at 580℃ for 12 hours to obtain the cathode material.

[0140] Example 3

[0141] (1) Preparation of cathode material precursor

[0142] 1) Prepare a metal salt solution with a mass concentration of 120 g / L as solution A, wherein the metal salts are nickel sulfate, cobalt sulfate and manganese sulfate, and the molar ratio of nickel, cobalt and manganese is Ni:Co:Mn = 96:03:01; prepare a sodium hydroxide solution with a mass percentage concentration of 32% as solution B; prepare an ammonia solution with a mass percentage concentration of 21% as solution C; at the same time, prepare an Al solution with a mass concentration of 0.56 g / L as solution D; prepare a W solution with a mass percentage concentration of 1.21 g / L as solution E.

[0143] 2) Add pure water, solution B and solution C to the seed crystal synthesis reactor to prepare the base solution. Control the pH value of the base solution to 11.7 and the mass concentration of ammonia water to 2.0 g / L. Introduce nitrogen gas as a protective gas.

[0144] Add pure water, solution B and solution C to the growth reactor to prepare the base solution. Control the pH value of the base solution to 11.25 and the mass concentration of ammonia water to 3.0 g / L. Introduce nitrogen gas as a protective gas.

[0145] 3) Solutions A, B, C, D, and E are simultaneously introduced into the seed crystal synthesis reactor. The flow rates of solutions A, B, C, D, and E are 4.00% h, 1.52% h, 0.03% h, 2.00% h, and 2.00% h of the available volume of the reactor, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.70, the ammonia concentration is maintained at 2.0 g / L, the reaction temperature is maintained at 60℃, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the seed crystal synthesis reactor reaches the overflow position, the overflow feed to the first growth reaction device begins.

[0146] 4) After the seed crystal synthesis reactor begins to overflow into the first growth reactor, solutions A, B, C, D, and E are simultaneously introduced into the first growth reactor. The flow rates of solutions A, B, C, D, and E are 8.00% / h, 3.04% / h, 0.06% / h, 4.00% / h, and 4.00% / h, respectively, of the available volume of the reaction vessel. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.20, the temperature is maintained at 60℃, and the ammonia concentration is maintained at 3.0 g / L. The stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the first growth reactor reaches the overflow position, overflow into the second growth reactor begins.

[0147] After the first growth reactor begins overflowing into the second growth reactor, solutions A, B, C, D, and E are simultaneously introduced into the second growth reactor. The flow rates of solutions A, B, C, D, and E are 8.00% / h, 3.04% / h, 0.06% / h, 4.00% / h, and 4.00% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.20, the temperature is maintained at 60℃, the ammonia concentration is maintained at 3.0 g / L, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the second growth reactor reaches the overflow position, overflowing into the third growth reactor begins.

[0148] After the second growth reactor begins overflowing into the third growth reactor, solutions A, B, C, D, and E are simultaneously introduced into the first growth reactor. The flow rates of solutions A, B, C, D, and E are 8.00% / h, 3.04% / h, 0.06% / h, 4.00% / h, and 4.00% / h, respectively, of the available volume of the reaction vessel. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.20, the temperature is maintained at 60℃, the ammonia concentration is maintained at 3.0 g / L, and the stirring device is controlled to stir at a speed of 400.35 r / min. When the slurry in the third growth reactor reaches the overflow position, the overflow yields the slurry of the cathode material precursor.

[0149] The reaction was stopped after the average particle size of the secondary particles in the slurry reached 3.5 μm. The resulting slurry was washed, centrifuged, dried, and demagnetized by sieving to obtain a product with the chemical formula Ni. 0.96 Co 0.03 Mn 0.01 (OH)2, wherein the W content is 172 ppm and the Al content is 572 ppm, is a cathode material precursor.

[0150] (2) Preparation of cathode materials

[0151] The obtained cathode material precursor was mixed with lithium hydroxide at a ratio of 1:1.05 and sintered at 580℃ for 12 hours to obtain the cathode material.

[0152] Example 4

[0153] (1) Preparation of cathode material precursor

[0154] 1) Prepare a metal salt solution with a mass concentration of 120 g / L as solution A, wherein the metal salts are nickel sulfate, cobalt sulfate and manganese sulfate, and the molar ratio of nickel, cobalt and manganese is Ni:Co:Mn=96:03:01; prepare a sodium hydroxide solution with a mass percentage concentration of 32% as solution B; and prepare an ammonia solution with a mass percentage concentration of 21% as solution C.

[0155] 2) Add pure water, solution B and solution C to the reactor to prepare the base solution. Control the pH of the base solution to 11.4 and the mass concentration of ammonia water to 5.5 g / L. Introduce nitrogen gas as a protective gas.

[0156] 3) During the 0-12h reaction process, solutions A, B, and C are simultaneously introduced into the reaction vessel. The flow rates of solutions A, B, and C are 3.00% / h, 2.22% / h, and 0.11% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is controlled to slowly decrease from 11.4 to 11.0, the ammonia concentration is maintained at 4.5 g / L, the reaction temperature is maintained at 60℃, the nickel concentration in the supernatant of the reaction system is maintained in the range of 0-60 ppm, and the stirring device is controlled to stir at a speed of 400.35 r / min.

[0157] 4) During the 12-24h reaction process, solutions A, B, and C are continuously introduced into the reactor simultaneously. The flow rates of solutions A, B, and C are 6.00%, 2.27%, and 2.25% of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.0, the temperature is maintained at 60℃, the ammonia concentration is maintained at 3.5g / L, the nickel concentration in the supernatant of the reaction system is maintained in the range of 0-60ppm, and the stirring device is controlled to stir at a speed of 400.35r / min.

[0158] After reacting for 25 hours, the mixture was split into two separate reactors, each with a volume equal to half the volume of the original reactor. During the subsequent 25 hours, solutions A, B, and C were simultaneously introduced into the reactor. The flow rates of solutions A, B, and C were 6.00% / h, 2.27% / h, and 2.25% / h of the available volume of the reaction vessel, respectively. The reaction was carried out under a protective gas atmosphere. During the reaction, the pH of the mixture was maintained at 11.0, the temperature at 60℃, the ammonia concentration at 3.5 g / L, and the nickel concentration in the supernatant of the reaction system was maintained within the range of 0-60 ppm. The stirring device was operated at a speed of 400.35 r / min.

[0159] The mother liquor is discharged using a concentration device throughout the entire process, and the discharge rate is consistent with the total feed rate.

[0160] The reaction was stopped when the average particle size of the secondary particles in the slurry reached 3.5 μm; the resulting slurry was washed, centrifuged, dried, and demagnetized by sieving to obtain a product with the chemical formula Ni. 0.96 Co 0.03 Mn 0.01 (OH)2 cathode material precursor.

[0161] (2) Preparation of cathode materials

[0162] The obtained cathode material precursor was mixed with lithium hydroxide at a ratio of 1:1.05 and sintered at 580℃ for 12 hours to obtain the cathode material.

[0163] Example 5

[0164] (1) Preparation of cathode material precursor

[0165] 1) Prepare a metal salt solution with a mass concentration of 110 g / L as solution A, wherein the metal salts are nickel sulfate, cobalt sulfate and manganese sulfate, and the molar ratio of nickel, cobalt and manganese is Ni:Co:Mn = 96:03:01; prepare a sodium hydroxide solution with a mass percentage concentration of 32% as solution B; and prepare an ammonia solution with a mass percentage concentration of 21% as solution C.

[0166] 2) Add pure water, solution B and solution C to the batch reactor to prepare the base solution. Control the pH value of the base solution to 11.7 and the mass concentration of ammonia water to 5.5 g / L. Introduce nitrogen gas as a protective gas.

[0167] 3) During the 0-16h reaction process, solutions A, B, and C were simultaneously introduced into the batch reactor. The flow rates of solutions A, B, and C were 3.00% / h, 2.22% / h, and 0.11% / h of the available volume of the reactor, respectively. The reaction was carried out under a protective gas atmosphere. During the reaction, the pH of the mixture was controlled to slowly decrease from 11.7 to 11.25, the ammonia concentration was maintained at 4.5 g / L, the reaction temperature was maintained at 60℃, the nickel concentration in the supernatant of the reaction system was maintained in the range of 0-60 ppm, and the stirring device was controlled to stir at a speed of 400.35 r / min.

[0168] 4) During the reaction process of more than 16 hours, solutions A, B and C are continuously introduced into the batch reactor simultaneously. The flow rates of solutions A, B and C are 6.00% h, 2.27% h and 2.25% h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.2, the temperature is maintained at 60℃, the ammonia concentration is maintained at 3.5 g / L, the nickel concentration in the supernatant of the reaction system is maintained in the range of 0-60 ppm, and the stirring device is controlled to stir at a speed of 400.35 r / min.

[0169] The mother liquor is discharged using a concentration device throughout the entire process, and the discharge rate is consistent with the total feed rate.

[0170] The reaction was stopped when the average particle size of the secondary particles in the slurry reached 3.5 μm; the resulting slurry was washed, centrifuged, dried, and demagnetized by sieving to obtain a product with the chemical formula Ni. 0.96 Co 0.03 Mn 0.01 (OH)2 cathode material precursor.

[0171] (2) Preparation of cathode materials

[0172] The obtained cathode material precursor was mixed with lithium hydroxide at a ratio of 1:1.05 and sintered at 580℃ for 12 hours to obtain the cathode material.

[0173] Example 6

[0174] (1) Preparation of cathode material precursor

[0175] 1) Prepare a metal salt solution with a mass concentration of 120 g / L as solution A, wherein the metal salts are nickel sulfate, cobalt sulfate and manganese sulfate, and the molar ratio of nickel, cobalt and manganese is Ni:Co:Mn=96:03:01; prepare a sodium hydroxide solution with a mass percentage concentration of 32% as solution B; and prepare an ammonia solution with a mass percentage concentration of 21% as solution C.

[0176] 2) Add pure water, solution B and solution C to the reactor to prepare the base solution. Control the pH of the base solution to 11.4 and the mass concentration of ammonia water to 5.5 g / L. Introduce nitrogen gas as a protective gas.

[0177] 3) During the 0-12h reaction process, solutions A, B, and C are simultaneously introduced into the reaction vessel. The flow rates of solutions A, B, and C are 3.00% / h, 2.22% / h, and 0.11% / h of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is controlled to slowly decrease from 11.4 to 11.0, the ammonia concentration is maintained at 4.5 g / L, the reaction temperature is maintained at 60℃, the nickel concentration in the supernatant of the reaction system is maintained in the range of 0-60 ppm, and the stirring device is controlled to stir at a speed of 400.35 r / min.

[0178] 4) During the 12-14h reaction process, solutions A, B, and C are continuously introduced into the reactor simultaneously. The flow rates of solutions A, B, and C are 6.00%, 2.35%, and 2.25% of the available volume of the reaction vessel, respectively. The reaction is carried out under a protective gas atmosphere. During the reaction, the pH of the mixture is maintained at 11.3, the temperature is maintained at 60℃, the ammonia concentration is maintained at 3.5g / L, the nickel concentration in the supernatant of the reaction system is maintained in the range of 0-60ppm, and the stirring device is controlled to stir at a speed of 400.35r / min.

[0179] During the reaction process 14 hours later, solutions A, B, and C were continuously introduced into the reactor simultaneously. The flow rates of solutions A, B, and C were 6.00% / h, 2.27% / h, and 2.25% / h of the available volume of the reaction vessel, respectively. The reaction was carried out under a protective gas atmosphere. During the reaction, the pH of the mixture was maintained at 11.1, the temperature was maintained at 60℃, the ammonia concentration was maintained at 3.5 g / L, the nickel concentration in the supernatant of the reaction system was maintained in the range of 0-60 ppm, and the stirring device was controlled to stir at a speed of 400.35 r / min.

[0180] The mother liquor is discharged using a concentration device throughout the entire process, and the discharge rate is consistent with the total feed rate.

[0181] The reaction was stopped when the average particle size of the secondary particles in the slurry reached 3.5 μm; the resulting slurry was washed, centrifuged, dried, and demagnetized by sieving to obtain a product with the chemical formula Ni. 0.96 Co 0.03 Mn 0.01 (OH)2 cathode material precursor.

[0182] (2) Preparation of cathode materials

[0183] The obtained cathode material precursor was mixed with lithium hydroxide at a ratio of 1:1.05 and sintered at 580℃ for 12 hours to obtain the cathode material.

[0184] Test data

[0185] 1. Physicochemical properties

[0186] In this application, in order to evaluate the cross-sectional structure (CP image) of the secondary particles, the prepared cathode material precursor particles are first vacuum-embedded on conductive adhesive, then the particles are cut, and finally the cut cathode material precursor powder is photographed under a field emission scanning electron microscope (HITACHI SU8100 series) to obtain the CP image of the secondary particles.

[0187] In this application, the testing method for the outer layer and core of the secondary particles is as follows: Generally, the seed crystal obtained in the preparation method is considered as the core of the secondary particle, and it continues to grow in the growth vessel to form the outer layer. From the image, it can be seen that... Figures 8-10 As shown in the figure, the internal structure of the secondary particles is clearly unevenly distributed with significant differences in pore structure. In this application, the honeycomb-like interior of the secondary particles is considered the core, and the area outside the core layer is considered the outer layer. The thickness of the core is half the longest axis of the honeycomb-like interior region, and the thickness of the outer shell is the radius of the secondary particle minus the thickness of the core layer.

[0188] In this application, porosity is a parameter characterizing particle morphology. It is calculated by directly determining the pore area and cross-sectional area of ​​a CP (Porosimetry) profile at a certain magnification (e.g., 5000-50000x) using image analysis software (ImageJ). The porosity of different regions is then calculated using the formula: "Porosity = Porosity of each region / Cross-sectional area of ​​each region × 100%". Several (e.g., 5) CP images can be used to calculate the porosity, and then the average value is taken. All porosities mentioned in this paper are obtained using this method.

[0189] In this application, to evaluate the average thickness, average aspect ratio, and average number of laminations of the primary particles, at least 10 secondary particles with particle sizes d within three ranges—d≥5.0μm, 5.0μm>d≥3.0μm, and 3μm>d≥1μm—were selected when determining the physicochemical properties of the cathode material precursor. (Secondary particle size measurement: the particle size of the secondary particle was measured using Nano Measurer software in four directions: the longest axis, the minor axis perpendicular to its midpoint, and the diagonal. The average value was then taken as the particle size.) The surface of a single secondary particle was photographed using an electron microscope with magnification of 50000× or 100000× (high magnification improves the accuracy of measurement for small particles). Then, Nano Measurer software was used to analyze the particle size. The Measurementr software was used to measure the length and thickness of primary particles on the surface of secondary particles under high magnification (at least 50 sets of individual primary particles were taken; the longest axis of a single primary particle was considered its length, and the short axis measured perpendicular to the midpoint of the longest axis was considered its width). The average value was then taken to obtain the average thickness and average length-to-thickness ratio of primary particles of different sizes. The average number of lamellar layers was obtained by dividing the average thickness by the theoretical interlayer spacing, which is 0.463 nm.

[0190] In this application, sphericity is a parameter characterizing particle morphology, which is the ratio of the surface area of ​​a sphere with the same volume to the surface area of ​​a particle. It is determined by taking multiple (e.g., 5) SEM images at a certain magnification (e.g., 1000×) using a field emission scanning electron microscope (HITACHI SU8100). The sphericity of each SEM image is analyzed using the sphericity calculation formula: sphericity = (4π × area) / (perimeter × perimeter) × 100%. The average of the sphericity of multiple (e.g., 5) SEM images is then taken as the final sphericity.

[0191] Table 1 Physicochemical data of cathode material precursors in each embodiment

[0192]

[0193]

[0194] Table 2. Physicochemical data of the cathode materials obtained from the cathode material precursors in each embodiment.

[0195] project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 <![CDATA[Compaction density (2t) (g / cm 3 )]]> 3.20 3.19 3.14 3.15 3.13 3.11 D50(μm) 4.0 4.2 3.9 4.2 4.1 4.0

[0196] 2. Electrochemical performance

[0197] In this application, a coin cell was used for electrochemical performance testing. The positive electrode materials prepared in the above embodiments 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 prepare the positive electrode sheet. The negative electrode sheet was a lithium metal sheet, and the electrolyte was a 1 mol / L LiPF6 / EC:DMC solution (volume ratio 1:1). The battery casing, positive electrode sheet, negative electrode sheet, separator, spring sheet, and gasket were assembled into a coin cell in a vacuum glove box. The electrochemical performance was tested using a Blue Electric testing system.

[0198] At room temperature, charge-discharge tests were conducted at 3.0-4.3V (1C = 210mA / g). The electrochemical performance of the cathode materials prepared in each example and comparative example is shown in Table 2.

[0199] Table 3. Electrochemical performance test data of the cathode materials obtained from the cathode material precursors in each embodiment.

[0200]

[0201]

[0202] Please refer to Tables 1-3 and Figures 1-10As shown, in each embodiment, the secondary particles have a compact core and a loose outer layer. The particle size of the secondary particles is positively correlated with the ratio of their outer core thickness; that is, as the number of secondary particles increases, the proportion of the core to the entire sphere gradually decreases, which can improve the stability and rate performance of the battery. Optionally, in Examples 1-3, the C-type particles have a small outer core thickness ratio (<1.20), and the A-type particles have a large outer core thickness ratio (>2.00), which can improve the stability and rate performance of the battery and reduce the cycle resistance.

[0203] Generally, during sintering, the smaller the particle size of the precursor, the stronger its heat transfer capacity. After sintering, the primary particles on the surface tend to agglomerate quickly, forming larger primary particles, which can easily lead to uneven sintering of primary particles between large and small particles. However, when the thickness and average number of lamellar layers of the primary particles are positively correlated with the particle size, type C particles have finer primary particles, fewer average lamellar layers, and higher porosity, while type A particles have coarser primary particles, more average lamellar layers, and lower porosity. This can alleviate the problem of uneven primary particle distribution on the surface of large and small particles during sintering, making the primary particles of the cathode material more uniform. This reduces the generation of cracks at high rates, improves the battery's rate performance, and lowers the cycle resistance. In Examples 1-3, the average thickness of the primary particles in type C particles is small (<20nm), while the average thickness of the primary particles in type A particles is large (>30nm). The large difference between the two can significantly improve the high-rate performance of the battery and reduce the cycle resistance.

[0204] A comparison of Examples 1-3 with Examples 5-6 shows that the samples prepared in Examples 1-2 have better sphericity (>90.00%). Excellent sphericity is beneficial to improving the filling density of the cathode material and thus the energy density of the battery.

[0205] Comparing Examples 1-2 with Examples 4-6, it can be seen that Examples 1-2 have a higher compaction density. This is because the precursor has a wider particle size distribution, and the morphological differences between small, medium and large particles are more obvious, making it easier to form a morphological gradient, which can compensate for each other's defects and improve the stability and rate performance of the battery. At the same time, the radial primary particles of Examples 1-2 are also conducive to withstanding greater pressure and improving compaction density.

[0206] Example 3 exhibits lower cycling resistance and better cycling stability at high rates because Al and W doping stabilizes the layered structure and increases interlayer spacing, promoting Li... + The migration of these molecules improves the rate performance and cycle stability of the material.

[0207] Finally, it should be noted that the technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0208] Furthermore, the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it; although the present 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; and these 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.

Claims

1. A cathode material precursor, said cathode material precursor comprising secondary particles composed of primary particles, characterized in that, The secondary particles include at least three types of secondary particles, all of which have a core-shell structure. The three types of secondary particles are A-type particles, B-type particles, and C-type particles, respectively. The particle size of the A-type particles, the B-type particles, and the C-type particles decreases sequentially. The thickness ratio t of the outer layer and the core of the A-type particles, the B-type particles, and the C-type particles decreases sequentially. Among the A-type particles, B-type particles, and C-type particles, the porosity of the outer layer of the same type of particle is greater than the porosity of its core. The particle size of type A particles is d ≥ 5.0 μm; the particle size of type B particles is d ≥ 3.0 μm (5.0 μm > d ≥ 3.0 μm); the particle size of type C particles is d ≥ 1 μm (3 μm > d ≥ 1 μm). The thickness ratio of the outer layer to the core of the type A particle is t A ≥2.0; The thickness ratio of the outer layer to the core of the type B particles is t B Satisfy: 2.0 > t B ≥1.2; The thickness ratio of the outer layer to the core of the C-type particle is t C Satisfy: 1.2 > t C ≥0.

3.

2. The cathode material precursor according to claim 1, characterized in that, The thickness ratio distribution of the A-type, B-type, and C-type particles is span = (t) A -t C ) / t B It is above 0.1; where t A It is the ratio of the thickness of the outer layer to the thickness of the core of a type A particle, t B It is the ratio of the outer layer to the core thickness of a type B particle, t C It is the ratio of the thickness of the outer layer to the thickness of the core of a Class C particle; And / or, the thickness ratio of the core of the A-type particles, B-type particles, and C-type particles is 1:0.8~1.2:0.8~1.

2.

3. The cathode material precursor according to claim 1 or 2, characterized in that, The particle size d of the type A particles is 6.5μm ≥ d ≥ 5.5μm; and / or, the particle size d of the type B particles is 4.5μm ≥ d ≥ 3.5μm; and / or, the particle size d of the type C particles is 2.5μm ≥ d ≥ 1.5μm; And / or, the thickness of the outer layer and the core of the type A particle is greater than t. A For 3.0≥t A ≥2.0; And / or, the thickness of the outer layer and the core of the type B particle is greater than t. B 1.9≥t B ≥1.3; And / or, the thickness of the outer layer and the core of the C-type particle is greater than t. C 1.19≥t C ≥0.5; And / or, the span of the thickness ratio distribution of the A-type particles, B-type particles, and C-type particles is (t) A -t C ) / t B It ranges from 0.4 to 1.

5.

4. The cathode material precursor according to claim 1 or 2, characterized in that, The A-type particles, the B-type particles, and the C-type particles satisfy at least one of the following conditions a to d: a. The average number of lamellae in the primary particles of the A-type particles, the B-type particles, and the C-type particles decreases sequentially; b. The average thickness of the primary particles of the A-type particles, the B-type particles, and the C-type particles decreases sequentially; c. The average length-to-thickness ratio of the primary particles of the A-type particles, the B-type particles, and the C-type particles increases sequentially; d. The overall porosity of the A-type particles, the B-type particles, and the C-type particles increases sequentially.

5. The cathode material precursor according to claim 4, characterized in that, The average thickness of the primary particles of the type A particles is 10~160nm; and / or, the average thickness of the primary particles of the type B particles is 10~130nm; and / or, the average thickness of the primary particles of the type C particles is 2~100nm. And / or, the average length-to-thickness ratio of the primary particles of the type A particles is 5 to 60; and / or, the average length-to-thickness ratio of the primary particles of the type B particles is 10 to 60; and / or, the average length-to-thickness ratio of the primary particles of the type C particles is 5 to 60. And / or, the overall porosity of the type A particles is 10%~30%; and / or, the overall porosity of the type B particles is 10%~30%; and / or, the overall porosity of the type C particles is 10%~40%.

6. The cathode material precursor according to claim 5, characterized in that, The average thickness of the primary particles of the type A particles is 30-70 nm; and / or, the average thickness of the primary particles of the type B particles is 30-70 nm; and / or, the average thickness of the primary particles of the type C particles is 4-30 nm. And / or, the average length-to-thickness ratio of the primary particles of the type A particles is 10-30; and / or, the average length-to-thickness ratio of the primary particles of the type B particles is 15-30; and / or, the average length-to-thickness ratio of the primary particles of the type C particles is 20-30. And / or, the overall porosity of the type A particles is 12%~25%; and / or, the overall porosity of the type B particles is 12%~25%; and / or, the overall porosity of the type C particles is 20%~35%.

7. The cathode material precursor according to claim 1 or 2, characterized in that, The cathode material precursor satisfies at least one of the following conditions a~i: a. The average particle size D50 of the cathode material precursor is 2~15μm; b. The span value of the particle size distribution of the cathode material precursor, which is (D95-D10) / D50, is 0.7~1.3; c. Sphericity R of the cathode material precursor q It is 70%~100%; d. The specific surface area (BET) of the cathode material precursor is 5~18 m². 2 / g; e. The tap density (TD) of the cathode material precursor is 1.2~3.0 g / cm³. 3 ; f. The full width at half maximum (FWHM) of the X-ray diffraction precursor of the cathode material is 0.210~0.550° and the full width at half maximum (FWHM) is 0.210~0.550°. g. The peak intensity ratio I(101) / I(001) of the X-ray diffraction test of the cathode material precursor is 1.00~1.50; h. The ratio of the grain size of the (101) crystal plane and the (001) crystal plane of the cathode material precursor, as determined by X-ray diffraction, is D(101) / D(001) = 2.0~2.5; i. The outer layer of the secondary particle has a thickness of 0.3~10 μm; the core of the secondary particle has a thickness of 0.3~2.0 μm.

8. The cathode material precursor according to claim 7, characterized in that, The cathode material precursor satisfies at least one of the following conditions a to h: a. The average particle size D50 of the cathode material precursor is 3.0-5.0 μm; b. The span value of the particle size distribution of the cathode material precursor, which is (D95-D10) / D50, is 0.8-1.2; c. Sphericity R of the cathode material precursor q It is 90%-100%; d. The specific surface area (BET) of the cathode material precursor is 12~15 m². 2 / g; e. The tap density (TD) of the cathode material precursor is 1.4~2.4 g / cm³. 3 ; f. The full width at half maximum (FWHM) of the X-ray diffraction test of the cathode material precursor is 0.230~0.500°, and / or, the FWHM(101) is 0.230~0.500°; g. The peak intensity ratio I(101) / I(001) of the X-ray diffraction test of the cathode material precursor is 1.01~1.40; h. The outer layer of the secondary particle has a thickness of 0.5~8μm; and / or, the core of the secondary particle has a thickness of 0.4~1.8μm.

9. The cathode material precursor according to claim 1 or 2, characterized in that, The chemical general formula of the positive electrode material precursor is Ni x Co y Mn 1-x-y-z M z )(OH)2, where 0.5 ≤ x < 1, 0 < y ≤ 0.5, 0 ≤ z < 0.5, x + y + z ≤ 1), and the doping element M is one or more of Ti, Mg, Zn, Cu, Al, Ga, In, La, Cr, Si, Sn, and W.

10. A method for preparing a cathode material precursor according to any one of claims 1-9, characterized in that, include: In the seed crystal synthesis process, a metal salt solution, a precipitant solution, and a complexing agent solution are simultaneously introduced into a reaction vessel containing a seed crystal synthesis substrate solution to react and obtain a seed crystal slurry. In the growth process, the seed slurry is sequentially passed through at least three growth reaction vessels containing growth substrate solutions, and a synthesis reaction is carried out in each growth reaction vessel using a metal salt solution, a precipitant solution, and a complexing agent solution that are simultaneously introduced to obtain the cathode material precursor; the seed slurry is sequentially fed into each growth reaction vessel by overflow. The pH of the seed crystal substrate is maintained at 10.00-13.00, and the concentration of the complexing agent in the seed crystal substrate is maintained at 0.5-5.0 g / L; the pH of the growth substrate is maintained at 10.00-13.00, and the concentration of the complexing agent in the growth substrate is maintained at 1.0-6.0 g / L; the pH of the seed crystal substrate is higher than that of the growth substrate, and the concentration of the complexing agent in the seed crystal substrate is lower than that in the growth substrate. In the seed crystal synthesis process, the metal salt solution includes a first metal salt solution and / or a second metal salt solution. The inflow rate of the first metal salt solution is 2.0~6.0% / h of the available volume of the seed crystal synthesis reaction vessel, and the inflow rate of the second metal salt solution is 40%-80% of the inflow rate of the first metal salt solution. The inflow rate of the precipitant solution is 0.5~2.0% / h of the available volume of the seed crystal synthesis reaction vessel. The inflow rate of the complexing agent solution is 0.01~0.50% / h of the available volume of the seed crystal synthesis reaction vessel. In the growth process, the metal salt solution includes a first metal salt solution and / or a second metal salt solution. The inflow rate of the first metal salt solution is 5.0~10.0% / h of the available volume of the seed crystal reaction vessel, and the inflow rate of the second metal salt solution is 40%-80% of the inflow rate of the first metal salt solution. The inflow rate of the precipitant solution is 1.0~5.0% / h of the available volume of the growth reaction vessel, and the inflow rate of the complexing agent solution is 0.01~3.50% / h of the available volume of the growth reaction vessel.

11. The method for preparing the cathode material precursor according to claim 10, characterized in that, The method satisfies at least one of the following conditions a to e: a. The metal salt includes a first metal salt and / or a second metal salt, wherein the first metal salt includes one or more combinations of nickel salt, cobalt salt, manganese salt, and dopant element salts, including at least nickel salt; and the second metal salt includes one or more combinations of dopant element salts. The precipitant includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. The complexing agent includes one or more of citric acid, ammonium citrate, oxalic acid, ammonium oxalate, ammonia, and ammonium carbonate; b. The pH of the seed crystal substrate solution is maintained at 10.5~12.50; c. The temperature of the synthetic seed solution is maintained at 40-80℃; the stirring speed of the synthetic seed solution is 200-500 r / min; d. The pH of the growth substrate is maintained at 10.5~12.50; e. The temperature of the growth substrate is maintained at 40-80℃; the stirring speed of the growth substrate is 200-500 r / min.

12. The method for preparing the cathode material precursor according to claim 11, characterized in that, The method satisfies at least one of the following conditions a to g: a. The sum of the mass concentrations of metal ions in the first metal salt solution is 50-160 g / L; and / or, the sum of the mass concentrations of metal ions in the second metal salt solution is 0.1-2.0 g / L; and / or, The mass percentage concentration of the precipitant solution is 20.0%-40.0%; and / or, The complexing agent solution has a mass percentage concentration of 10.1% to 30.5%; b. The concentration of the complexing agent in the seed crystal substrate is maintained at 1.5-3.5 g / L; c. The temperature of the synthetic seed solution is maintained at 55-70℃; and / or the stirring speed of the synthetic seed solution is 250-450 r / min; d. The concentration of the complexing agent in the growth substrate is maintained at 2.5-4.5 g / L; e. The temperature of the growth substrate is maintained at 55-70°C; and / or the stirring speed of the growth substrate is 250-450 r / min; f. In the seed crystal synthesis process, the influent rate of the first metal salt solution is 2.5-4.5% / h of the available volume of the seed crystal synthesis reaction vessel; and / or, the influent rate of the precipitant solution is 1.0-1.8% / h of the available volume of the seed crystal synthesis reaction vessel; and / or, the influent rate of the complexing agent solution is 0.01-0.10% / h of the available volume of the seed crystal synthesis reaction vessel. g. In the growth process, the inflow rate of the first metal salt solution is 7.0~9.0% / h of the available volume of the seed crystal reaction vessel; and / or, the inflow rate of the precipitant solution is 2.5~4.0% / h of the available volume of the growth reaction vessel; and / or, the inflow rate of the complexing agent solution is 0.01~0.10% / h of the available volume of the growth reaction vessel.

13. The method for preparing the cathode material precursor according to claim 11 or 12, characterized in that, The sum of the mass concentrations of metal ions in the first metal salt solution is 60-150 g / L; and / or, the sum of the mass concentrations of metal ions in the second metal salt solution is 0.5-1.5 g / L; and / or, The mass percentage concentration of the precipitant solution is 25.0%~35.0%; and / or, The complexing agent solution has a mass percentage concentration of 15.0% to 25.0%.

14. A positive electrode material, characterized in that, The raw materials for the cathode material include the cathode material precursor as described in any one of claims 1-9.

15. A secondary battery, comprising a positive electrode, characterized in that, The positive electrode sheet includes the positive electrode material according to claim 14.

16. An electrical-related device, characterized in that, Includes the secondary battery as described in claim 15.

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