Cobalt oxyhydroxide, preparation method therefor, positive electrode material, battery and electrical device

Abstract

The present invention belongs to the field of batteries, and in particular relates to a cobalt oxyhydroxide, a preparation method therefor, a positive electrode material, a battery, and an electrical device. The grain size of the cobalt oxyhydroxide provided in the present application at a (003) crystal plane is D(003)=100~290Å, the (003) crystal plane corresponding to a diffraction peak at a diffraction angle 2θ of 19°-21°. The cobalt oxyhydroxide has an appropriate grain size on the (003) crystal plane, helping to improve the crushing effect of the cobalt oxyhydroxide, the dispersion performance and coating performance of the cobalt oxyhydroxide mixed with positive electrode materials, and the cycle performance of batteries prepared from coated and sintered positive electrode materials.

Description

Cobalt oxyhydroxide, preparation method thereof, positive electrode material, battery and electrical equipment

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202410862752.2, filed on June 28, 2024, entitled “Cobalt oxyhydroxide, preparation method thereof, positive electrode material, battery and electrical equipment”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the field of batteries, and particularly relates to a cobalt oxyhydroxide, a preparation method thereof, a positive electrode material, a battery and an electrical equipment. BACKGROUND

[0004] The positive electrode material is an important component of lithium / sodium ion batteries, and is mainly used to complete the conversion of electric energy by embedding or removing lithium / sodium ions into or out of the electrode structure during charging and discharging. In the preparation of the positive electrode material, the introduction of additives is one of the effective ways to improve the electrical performance of lithium / sodium ion batteries at present.

[0005] In the prior art, nanoscale cobaltous hydroxide, cobalt oxyhydroxide and other materials after crushing are usually used as additives to modify the coating of the positive electrode material, so as to improve the charging and discharging capacity, output power, charging and discharging cycle life of the battery, and reduce the resistance after multiple cycles. However, due to the influence of factors such as the morphology, particle size and crystal structure of the additive material, the coating effect of the additive material in the prior art on the positive electrode material is not good, which inhibits the electrical performance of lithium / sodium ion batteries. SUMMARY

[0006] The present application provides a cobalt oxyhydroxide, a preparation method thereof, a positive electrode material, a battery and an electrical equipment, which aims to solve or at least alleviate the defects existing in the prior art.

[0007] The first aspect of the present application provides a cobalt oxyhydroxide, wherein the XRD pattern of the cobalt oxyhydroxide has a grain size of the cobalt oxyhydroxide at a (003) crystal face of the diffraction peak at a (003) crystal face corresponds to a diffraction angle 2θ of 19°-21°.

[0008] The grain size of the cobalt oxyhydroxide at the (003) crystal face is Having a smaller grain size is conducive to improving the crushing effect of the cobalt oxyhydroxide, improving the dispersion performance and coating performance after mixing with the positive electrode material, and improving the cycle performance of the battery prepared by coating and sintering the positive electrode material.

[0009] In some embodiments, the cobalt oxyhydroxide satisfies at least one of the following conditions:

[0010] A, the grain size of cobalt oxyhydroxide on the (003) crystal plane Optionally,

[0011] B, the half peak width FWHM(003) of the diffraction peak corresponding to the (003) crystal plane in the XRD pattern of the cobalt oxyhydroxide is 0.29°-0.84°; optionally, the FWHM(003) is 0.29°-0.53°; optionally, the FWHM(003) is 0.35°-0.53°;

[0012] C, the mass fraction of alkali metal in the cobalt oxyhydroxide is ≤70 ppm; optionally, the mass fraction of alkali metal in the cobalt oxyhydroxide is 10-65 ppm; optionally, the mass fraction of sodium in the cobalt oxyhydroxide is 10-65 ppm;

[0013] D, the average particle size D50 of the cobalt oxyhydroxide is ≤0.22 μm; optionally, the D50 is ≤0.16 μm; optionally, 0.11 μm≤D50≤0.16 μm.

[0014] In some embodiments, the cobalt oxyhydroxide satisfies at least one of the following conditions:

[0015] F, the particle size D10 of the cobalt oxyhydroxide is ≤0.090 μm; optionally, 0.06 μm≤D10≤0.09 μm;

[0016] G, the particle size D90 of the cobalt oxyhydroxide is ≤2.1 μm; optionally, the D90 is ≤1.3 μm; optionally, 0.2 μm≤D90≤0.8 μm;

[0017] H, the particle size distribution Span of the cobalt oxyhydroxide is (D90-D10) / D50, and the Span is 1-10; optionally, the Span is 1.5-5.5; optionally, the Span is (D90-D10) / D50, and the Span is 1.5-4.0;

[0018] When the cobalt oxyhydroxide provided in the present application satisfies the above particle size requirements after crushing, the cobalt oxyhydroxide is well dispersed on the surface of the positive electrode material after coating the positive electrode material, and there is no agglomeration or less agglomeration of the cobalt oxyhydroxide, which is beneficial to the improvement of the electrochemical performance of the coated positive electrode material.

[0019] I, the mass fraction of Cl in the cobalt oxyhydroxide is ≤300 ppm; optionally, the mass fraction of Cl in the cobalt oxyhydroxide is ≤200 ppm;

[0020] J, the mass fraction of S in the cobalt oxyhydroxide is ≤600 ppm; optionally, the mass fraction of S in the cobalt oxyhydroxide is ≤300 ppm;

[0021] In some embodiments, the cobalt oxyhydroxide satisfies at least one of the following conditions:

[0022] K, the specific surface area BET of the cobalt oxyhydroxide is 40-150 m 2 / g;

[0023] L, the apparent density AD of the cobalt oxyhydroxide is 0.15-0.42 g / cm 3 ; optionally, the AD is 0.15-0.35 g / cm 3 ;

[0024] M, the particles of the cobalt oxyhydroxide are nanosheet lamellar and / or nanodot;

[0025] N, the chemical formula of the cobalt oxyhydroxide is aCoOOH.bCo3O4.(1-a-b)Co(OH)2, wherein 0.5≤a≤1, 0≤b≤0.5, and 0≤1-a-b≤0.2;

[0026] O, the chemical formula of the cobalt oxyhydroxide is xCoOOH.(1-x)Co3O4, wherein 0.85≤x≤1; optionally, 0.94≤x≤1.

[0027] A second aspect of the present application provides a preparation method of the cobalt oxyhydroxide as described above, comprising:

[0028] a synthesis process: adding a cobalt salt solution, a precipitant, and an oxidant into a base solution to perform a synthesis reaction, and preparing a post-reaction slurry;

[0029] a post-treatment process: post-treating the post-reaction slurry to obtain the cobalt oxyhydroxide;

[0030] In the reaction process of the synthesis process, the flow rate ratio of the cobalt salt solution, the precipitant, and the oxidant is 1:(0.25-0.80):(0.05-0.60).

[0031] In some embodiments, the preparation method of the cobalt oxyhydroxide satisfies at least one of the following conditions:

[0032] a, in the synthesis process, the concentration of hydroxide ions in the base solution is 1-6.5 mol / L; optionally, the concentration of hydroxide ions in the base solution is 1-3 mol / L.

[0033] b, the post-treatment process specifically comprises: sequentially performing washing, drying, and crushing treatment on the post-reaction slurry to obtain the cobalt oxyhydroxide;

[0034] c, the cobalt salt solution comprises at least one of cobalt chloride, cobalt sulfate, or cobalt nitrate;

[0035] d, the precipitant comprises at least one of potassium hydroxide solution or sodium hydroxide solution;

[0036] e. the oxidizing agent comprises at least one of hydrogen peroxide, sodium hypochlorite, sodium persulfate or ammonium persulfate.

[0037] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0038] f. the mass concentration of cobalt ions in the cobalt salt solution is 1-3 mol / L;

[0039] g. the mass fraction of the solute in the precipitant is 28-36 wt%;

[0040] h. the mass fraction of the solute in the oxidizing agent is 25-30 wt%;

[0041] i. the synthesis process is carried out in a reaction container, and the flow rate of the cobalt salt solution is 5-25% of the volume of the reaction container per hour;

[0042] j. the synthesis process is carried out in a reaction container, and the reaction is ended when the reaction reaches 70-90% of the volume of the reaction container;

[0043] k. the reaction temperature of the synthesis process is controlled to be 35-70℃;

[0044] l. the synthesis reaction is carried out under stirring, and the stirring rate is controlled to be 240-500 r / min;

[0045] m. in the post-processing process, when the drying treatment is carried out, the temperature of the drying is 120-140℃, and / or the time of the drying is controlled to be 15-25 h.

[0046] The third aspect of the present application provides a positive electrode material, a coating material of the positive electrode material or a raw material of the coating material of the positive electrode material, which comprises the cobalt oxyhydroxide as described above, and the amount of the cobalt oxyhydroxide is 1-5 wt% of the mass of the positive electrode material.

[0047] The fourth aspect of the present application provides a battery, which comprises a positive electrode made of the positive electrode material as described above, and the battery is a lithium ion battery or a sodium ion battery.

[0048] The fifth aspect of the present application provides an electrical equipment, which comprises the battery as described above. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0050] Figure 1 is a surface SEM photograph of cobalt oxyhydroxide prepared in Example 1 of the present application (magnification of 5000 times) ;

[0051] Figure 2 is a surface SEM photograph of cobalt oxyhydroxide prepared in Example 1 of the present application (magnification of 50000 times) ;

[0052] Figure 3 is a surface SEM photograph of cobalt oxyhydroxide prepared in Example 2 of the present application (magnification of 5000 times in the left photograph and magnification of 200000 times in the right photograph) ;

[0053] Figure 4 is a surface SEM photograph of cobalt oxyhydroxide prepared in Example 3 of the present application (magnification of 5000 times in the left photograph and magnification of 200000 times in the right photograph) ;

[0054] Figure 5 is a surface SEM photograph of cobalt oxyhydroxide prepared in Example 4 of the present application (magnification of 5000 times in the left photograph and magnification of 50000 times in the right photograph) ;

[0055] Figure 6 is a surface SEM photograph of cobalt oxyhydroxide prepared in Example 5 of the present application (magnification of 5000 times in the left photograph and magnification of 200000 times in the right photograph) ;

[0056] Figure 7 is a surface SEM photograph of cobalt oxyhydroxide prepared in Example 6 of the present application (magnification of 5000 times in the left photograph and magnification of 200000 times in the right photograph) ;

[0057] Figure 8 is a surface SEM photograph of cobalt oxyhydroxide prepared in Comparative Example 1 of the present application (magnification of 5000 times in the left photograph and magnification of 200000 times in the right photograph) ;

[0058] Figure 9 is a surface SEM photograph of cobalt oxyhydroxide prepared in Comparative Example 2 of the present application (magnification of 5000 times in the left photograph and magnification of 50000 times in the right photograph) ;

[0059] Figure 10 is an XRD pattern of cobalt oxyhydroxide prepared in Example 1 of the present application;

[0060] Figure 11 is an XRD pattern of cobalt oxyhydroxide prepared in Example 2 of the present application;

[0061] Figure 12 is an XRD pattern of cobalt oxyhydroxide prepared in Example 3 of the present application;

[0062] Figure 13 is an XRD pattern of cobalt oxyhydroxide prepared in Example 4 of the present application;

[0063] Figure 14 is an XRD pattern of cobalt oxyhydroxide prepared in Example 5 of the present application;

[0064] Figure 15 is an XRD pattern of cobalt oxyhydroxide prepared in Example 6 of the present application;

[0065] Figure 16 is an XRD pattern of cobalt oxyhydroxide prepared in the present application Comparative Example 1;

[0066] Figure 17 is an XRD pattern of cobalt oxyhydroxide prepared in the present application Comparative Example 2;

[0067] Figure 18 is a surface SEM photograph of the positive electrode material prepared from cobalt oxyhydroxide of the present application Example 1 (magnification 10000 times) ;

[0068] Figure 19 is a surface SEM photograph of the positive electrode material prepared from cobalt oxyhydroxide of the present application Example 2 (magnification 10000 times) ;

[0069] Figure 20 is a surface SEM photograph of the positive electrode material prepared from cobalt oxyhydroxide of the present application Example 3 (magnification 10000 times) ;

[0070] Figure 21 is a surface SEM photograph of the positive electrode material prepared from cobalt oxyhydroxide of the present application Example 4 (magnification 10000 times) ;

[0071] Figure 22 is a surface SEM photograph of the positive electrode material prepared from cobalt oxyhydroxide of the present application Example 5 (magnification 10000 times) ;

[0072] Figure 23 is a surface SEM photograph of the positive electrode material prepared from cobalt oxyhydroxide of the present application Example 6 (magnification 10000 times) ;

[0073] Figure 24 is a surface SEM photograph of the positive electrode material prepared from cobalt oxyhydroxide of the present application Comparative Example 1 (magnification 10000 times) ;

[0074] Figure 25 is a surface SEM photograph of the positive electrode material without coating of the present application Comparative Example (magnification 10000 times).

[0075] Wherein, Heterogentie in the XRD pattern is the name of standard diffraction card (PDF card) CoHO2, CoHO2 is CoOOH; Cobalt hydroxide is the name of PDF card Co(OH)2. DETAILED DESCRIPTION

[0076] The ranges disclosed herein are intended to be "open" ranges, i.e., the end values are not included in the range. The ranges are intended to be inclusive of the end values unless otherwise indicated. For example, if a range is listed as 60-120 and 80-110, it is intended that 60-110 and 80-120 are also disclosed. In addition, if a minimum range value of 1 and 2 is listed, and a maximum range value of 3, 4, and 5 is listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" is intended to indicate any and all sub-combinations of the values in a to b, in which a and b are both real numbers. For example, the numerical range "0-5" is intended to indicate that all real numbers between 0 and 5, inclusive of 0 and 5, have been listed herein. In addition, when a parameter is stated to be an integer > 2, it is equivalent to state that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0077] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0078] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0079] All steps of the present application can be performed in sequence or randomly, unless otherwise specified. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method further comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0080] Unless otherwise specified, "including" and "comprising" mentioned in the present application are open-ended, which can also be closed. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0081] Unless otherwise specified, in the present application, the term "and / or" is inclusive. For example, the phrase "A and / or B" means "A, B, or both A and B".

[0082] It should be noted that the "half-peak width" of the diffraction peak corresponding to a certain crystal face in the XRD pattern described in the present application and the "crystal grain size" calculated from the data in the XRD pattern are the meanings known in the art. For example, the half-peak width FWHM(003) of the diffraction peak corresponding to the (003) crystal face in the XRD pattern of cobalt oxyhydroxide represents the width of the diffraction peak corresponding to the (003) crystal face at half the peak height, and the unit is degree (°). The crystal grain size D (003) refers to the crystal grain size obtained by fitting the numerical value of the diffraction peak corresponding to the (003) crystal face, and the unit is angstrom which can be calculated by the Scherrer formula D = Kλ / (βcosθ), wherein K is the Scherrer constant, λ is the X-ray wavelength, β is the half-peak width of the diffraction peak corresponding to the (003) crystal face, and θ is the diffraction angle of the (003) crystal face.

[0083] It should be understood that in some embodiments, since the primary particles in the microstructure of cobalt oxyhydroxide in Examples 1-6 and Comparative Example 2 of the present application are close to cubic particles, and β is the half-peak width of the diffraction peak, the Scherrer constant K should be selected as 0.943; in addition, the half-peak width and θ should also be converted to radians before calculation.

[0084] For example, the crystal grain size D (003) of cobalt oxyhydroxide in the (003) crystal face is calculated from the XRD characterization data of cobalt oxyhydroxide in Example 1 of the present application. In the above Scherrer formula, K = 0.943 is selected, the X-ray wavelength λ is

[0085] The first aspect of the present application provides a cobalt oxyhydroxide, and in the XRD pattern of the cobalt oxyhydroxide, the crystal grain size D of the cobalt oxyhydroxide in the (003) crystal face is

[0086] To improve the coating effect of the additive material on the positive electrode material and improve the electrical performance of the lithium battery, one embodiment of the present application provides a cobalt oxyhydroxide, and in the XRD pattern of the cobalt oxyhydroxide, the crystal grain size D By designing the crystal grain size of the (003) crystal face of the cobalt oxyhydroxide, the cobalt oxyhydroxide has a smaller crystal grain size, which is beneficial to improve the crushing effect of the cobalt oxyhydroxide, improve the dispersion performance and coating performance after mixing with the positive electrode material, and improve the cycle performance of the battery prepared by coating and sintering the positive electrode material.

[0087] It should be understood that the grain size D of the cobalt oxyhydroxide on the (003) crystal plane is greater than 0.2 μm and less than 0.6 μm. (003) greater than When the grain size of the crushed cobalt oxyhydroxide is too large and the specific surface area is small, the crushing effect of the cobalt oxyhydroxide is poor, which leads to poor dispersion and coating performance of the cobalt oxyhydroxide on the positive electrode material, and the performance of the lithium battery cannot be effectively improved.

[0088] In the embodiments of the present application, the grain size D of the cobalt oxyhydroxide on the (003) crystal plane is greater than 0.2 μm and less than 0.6 μm. For example, the grain size D of the cobalt oxyhydroxide on the (003) crystal plane is greater than 0.2 μm and less than 0.6 μm. (003) may be or any size value within the range of 0.2 μm to 0.6 μm.

[0089] In some optional embodiments of the present application, the grain size D of the cobalt oxyhydroxide on the (003) crystal plane is greater than 0.2 μm and less than 0.6 μm. The grain size D of the cobalt oxyhydroxide on the (003) crystal plane is greater than 0.2 μm and less than 0.6 μm. (003) In the above range.

[0090] In some optional embodiments of the present application, the grain size D of the cobalt oxyhydroxide on the (003) crystal plane is greater than 0.2 μm and less than 0.6 μm. The grain size D of the cobalt oxyhydroxide on the (003) crystal plane is greater than 0.2 μm and less than 0.6 μm. (003) In the above range, the capacity performance of the battery prepared by coating and sintering the positive electrode material can also be improved.

[0091] In some embodiments of the present application, the half-peak width FWHM(003) of the diffraction peak corresponding to the (003) crystal plane in the XRD pattern of the cobalt oxyhydroxide is 0.29° to 0.84°. The cobalt oxyhydroxide has a suitable grain size on the (003) crystal plane and a suitable half-peak width of the corresponding diffraction peak, so that the cobalt oxyhydroxide has a suitable crystallinity, which helps to improve the crushing effect of the cobalt oxyhydroxide, and the cobalt oxyhydroxide can be uniformly dispersed and coated on the surface of the positive electrode material. There is less agglomerated cobalt oxyhydroxide or agglomerated cobalt oxyhydroxide, which is beneficial to the improvement of the electrochemical performance after coating.

[0092] In the embodiments of the present application, the FWHM (003) of the diffraction peak corresponding to the (003) crystal face in the XRD pattern of the cobalt oxyhydroxide is 0.29°-0.84°, for example, the FWHM (003) of the diffraction peak corresponding to the (003) crystal face in the XRD pattern of the cobalt oxyhydroxide can be 0.290°, 0.295°, 0.310°, 0.325°, 0.330°, 0.345°, 0.350°, 0.360°, 0.375°, 0.380°, 0.395°, 0.410°, 0.425°, 0.430°, 0.445°, 0.450°, 0.460°, 0.475°, 0.480°, 0.495°, 0.510°, 0.525°, 0.530°, 0.545°, 0.550°, 0.560°, 0.575°, 0.580°, 0.595°, 0.610°, 0.625°, 0.630°, 0.645°, 0.650°, 0.660°, 0.675°, 0.680°, 0.695°, 0.710°, 0.725°, 0.730°, 0.745°, 0.750°, 0.760°, 0.775°, 0.780°, 0.795°, 0.810°, 0.825°, 0.84°, or can be any value within the range of 0.29°-0.84°, 0.29°-0.43°, 0.43°-0.59°, 0.59°-0.84°, 0.40°-0.60°, 0.42°-0.53°, 0.52°-0.59°, etc., all of which can improve the crushing effect of the cobalt oxyhydroxide, so that the cobalt oxyhydroxide has more excellent dispersibility on the surface of the positive electrode material, to improve the electrochemical performance of the coated positive electrode material.

[0093] In some optional embodiments of the present application, the FWHM (003) of the diffraction peak corresponding to the (003) crystal face in the XRD pattern of the cobalt oxyhydroxide is 0.29°-0.53°.

[0094] In some optional embodiments of the present application, the FWHM (003) of the diffraction peak corresponding to the (003) crystal face in the XRD pattern of the cobalt oxyhydroxide is 0.35°-0.53°; when the FWHM (003) of the diffraction peak corresponding to the (003) crystal face in the XRD pattern of the cobalt oxyhydroxide is 0.35°-0.53°, the cobalt oxyhydroxide coated positive electrode material can be uniformly dispersed on the surface of the positive electrode material, and there is less agglomerated cobalt oxyhydroxide or agglomerated cobalt oxyhydroxide, which can further improve the cycle performance and capacity of the coated positive electrode material.

[0095] In some embodiments of the present application, the mass fraction of alkali metal in cobalt oxyhydroxide is ≤70 ppm; for example, the mass fraction of alkali metal in cobalt oxyhydroxide can be ≤70 ppm, ≤65 ppm, ≤60 ppm, ≤55 ppm, ≤50 ppm, ≤45 ppm, ≤40 ppm, ≤35 ppm, ≤30 ppm, ≤25 ppm, ≤20 ppm, ≤15 ppm, ≤10 ppm, ≤5 ppm, or can be any value in the range of 5-10 ppm, 10-70 ppm, 10-25 ppm, 25-60 ppm, 60-70 ppm, etc.

[0096] Optionally, the mass fraction of alkali metal in cobalt oxyhydroxide is 10-65 ppm; wherein the alkali metal includes sodium, and further, the mass fraction of sodium in cobalt oxyhydroxide is 10-65 ppm. The mass fraction of alkali metal in cobalt oxyhydroxide is low, and the cobalt oxyhydroxide has high purity, which is conducive to reducing the interface resistance of the coated positive electrode material, improving the electron conduction efficiency, reducing the direct current resistance of the coated positive electrode material after charge and discharge cycles, and significantly improving the cycle performance of the positive electrode material.

[0097] In some embodiments of the present application, the mass fraction of Cl in cobalt oxyhydroxide is ≤300 ppm; for example, the mass fraction of Cl in cobalt oxyhydroxide can be ≤300 ppm, ≤290 ppm, ≤280 ppm, ≤270 ppm, ≤260 ppm, ≤250 ppm, ≤240 ppm, ≤230 ppm, ≤220 ppm, ≤210 ppm, ≤200 ppm, ≤190 ppm, ≤180 ppm, ≤170 ppm, ≤160 ppm, ≤150 ppm, ≤140 ppm, ≤130 ppm, ≤120 ppm, ≤110 ppm, ≤100 ppm, ≤90 ppm, ≤80 ppm, ≤70 ppm, ≤60 ppm, ≤50 ppm, ≤40 ppm, ≤30 ppm, ≤20 ppm, ≤10 ppm, or can be any value in the range of 10-300 ppm, 10-100 ppm, 100-200 ppm, 200-300 ppm, 170-250 ppm, etc.

[0098] Optionally, the mass fraction of Cl in cobalt oxyhydroxide is ≤200 ppm. The mass fraction of Cl in cobalt oxyhydroxide is low, and the cobalt oxyhydroxide has high purity, which is conducive to reducing the interface resistance of the coated positive electrode material, improving the electron conduction efficiency, reducing the direct current resistance of the coated positive electrode material after charge and discharge cycles, and significantly improving the cycle performance of the positive electrode material.

[0099] In some embodiments of the present application, the mass fraction of S in the cobalt oxyhydroxide is ≤600 ppm; for example, the mass fraction of S in the cobalt oxyhydroxide can be ≤600 ppm, ≤580 ppm, ≤560 ppm, ≤540 ppm, ≤520 ppm, ≤500 ppm, ≤480 ppm, ≤460 ppm, ≤440 ppm, ≤420 ppm, ≤400 ppm, ≤380 ppm, ≤360 ppm, ≤340 ppm, ≤320 ppm, ≤300 ppm, ≤280 ppm, ≤260 ppm, ≤240 ppm, ≤220 ppm, ≤200 ppm, ≤180 ppm, ≤160 ppm, ≤140 ppm, ≤120 ppm, ≤100 ppm, ≤80 ppm, ≤60 ppm, ≤40 ppm, ≤20 ppm, or can be any value in the range of 20-600 ppm, 20-200 ppm, 200-400 ppm, 400-600 ppm, 240-550 ppm, 240-470 ppm, 470-550 ppm, etc.

[0100] Optionally, the mass fraction of S in the cobalt oxyhydroxide is ≤300 ppm; the mass fraction of S in the cobalt oxyhydroxide is low, and the cobalt oxyhydroxide has high purity, which is beneficial to reduce the interface resistance of the coated positive electrode material, improve the electron conduction efficiency, reduce the direct current resistance of the coated positive electrode material after charge and discharge cycles, and significantly improve the cycle performance of the positive electrode material.

[0101] In addition, impurities such as sodium, sulfate, chlorine, etc. can increase the irreversible capacity of the material. By controlling the content of impurities, the irreversible capacity is reduced when the material is used as a positive electrode active material of a battery, and high coulombic efficiency can be obtained.

[0102] It should be noted that the alkali metal in the cobalt oxyhydroxide in the embodiments of the present application mainly refers to the impurity metal introduced in the preparation process; for example, the alkali metal can be sodium or potassium introduced by an alkali metal salt. The Cl or S in the cobalt oxyhydroxide mainly refers to the non-metallic impurities introduced by the alkali metal salt introduced in the preparation process, such as Cl introduced by cobalt chloride, SO4 2- in S introduced by cobalt sulfate, etc.

[0103] In some embodiments of the present application, the average particle size D50 of the cobalt oxyhydroxide is ≤0.22 μm; for example, the average particle size D50 of the cobalt oxyhydroxide can be ≤0.22 μm, ≤0.21 μm, ≤0.20 μm, ≤0.19 μm, ≤0.18 μm, ≤0.17 μm, ≤0.16 μm, ≤0.15 μm, ≤0.14 μm, ≤0.13 μm, ≤0.12 μm, ≤0.11 μm, ≤0.10 μm, ≤0.09 μm, ≤0.08 μm, ≤0.07 μm, ≤0.06 μm, ≤0.05 μm, ≤0.04 μm, ≤0.03 μm, ≤0.02 μm, ≤0.01 μm, or can be any value in the range of 0.01-0.10 μm, 0.10-0.16 μm, 0.16-0.20 μm, 0.06-0.18 μm, etc.

[0104] Optionally, the average particle size D50 of the cobalt oxyhydroxide is ≤0.16 μm, and optionally, 0.11 μm≤D50≤0.16 μm.

[0105] When the average particle size of the cobalt oxyhydroxide is in the range of D50≤0.22 μm, especially 0.11 μm≤D50≤0.16 μm, the cobalt oxyhydroxide is more likely to be broken, and after being broken, finer particles can be formed, and the non-agglomerated cobalt oxyhydroxide or the agglomerated cobalt oxyhydroxide is less, so as to enhance the dispersibility of the cobalt oxyhydroxide on the surface of the positive electrode material, and facilitate the further improvement of the electrochemical performance of the coated positive electrode material.

[0106] In some embodiments of the present application, the particle size D10 of the cobalt oxyhydroxide is ≤0.090 μm; for example, the average particle size D10 of the cobalt oxyhydroxide can be ≤0.09 μm, ≤0.08 μm, ≤0.07 μm, ≤0.06 μm, ≤0.05 μm, ≤0.04 μm, ≤0.03 μm, ≤0.02 μm, ≤0.01 μm, or can be any value in the range of 0.01-0.09 μm, 0.01-0.07 μm, 0.07-0.09 μm, 0.06-0.09 μm, 0.070-0.085 μm, etc.

[0107] Optionally, 0.06 μm≤D10≤0.09 μm; when the particle size D10 of the cobalt oxyhydroxide is in this range, the cobalt oxyhydroxide is more likely to be broken, and after being broken, finer particles can be formed, so as to enhance the dispersibility of the cobalt oxyhydroxide on the surface of the positive electrode material, and facilitate the further improvement of the electrochemical performance of the coated positive electrode material.

[0108] In some embodiments of the present application, the particle size D90 of cobalt oxyhydroxide is ≤2.1 μm; for example, the average particle size D90 of cobalt oxyhydroxide can be ≤2.1 μm, ≤2.0 μm, ≤1.9 μm, ≤1.8 μm, ≤1.7 μm, ≤1.6 μm, ≤1.5 μm, ≤1.4 μm, ≤1.3 μm, ≤1.2 μm, ≤1.1 μm, ≤1.0 μm, ≤0.9 μm, ≤0.8 μm, ≤0.7 μm, ≤0.6 μm, ≤0.5 μm, ≤0.4 μm, ≤0.3 μm, ≤0.2 μm, ≤0.1 μm, or can be any value in the range of 0.1-2.4 μm, 0.1-1.3 μm, 0.1-0.2 μm, 0.3-0.7 μm, 0.7-1.3 μm, 1.3-2.1 μm, 0.5-2.0 μm, etc.

[0109] Optionally, D90 is ≤1.3 μm; optionally, 0.2 μm≤D90≤0.8 μm; when the particle size D90 of cobalt oxyhydroxide is in this range, the particles of cobalt oxyhydroxide are smaller as a whole and are more easily broken, so as to enhance the dispersibility of cobalt oxyhydroxide on the surface of the positive electrode material and facilitate further improvement of the electrochemical performance of the coated positive electrode material.

[0110] It should be noted that the particle size D50 in the embodiments of the present application refers to the particle size corresponding to 50% of the cumulative particle size distribution percentage of cobalt oxyhydroxide; the particle size D10 refers to the particle size corresponding to 10% of the cumulative particle size distribution percentage of cobalt oxyhydroxide; and the particle size D90 refers to the particle size corresponding to 90% of the cumulative particle size distribution percentage of cobalt oxyhydroxide.

[0111] In some embodiments of the present application, the particle size distribution Span of cobalt oxyhydroxide is (D90-D10) / D50=1-10; for example, the particle size distribution Span of cobalt oxyhydroxide can be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or can be any value in the range of 1.5-2.0, 2.0-3.0, 3.0-4.0, 4.0-5.5, 7-8, 2-8, etc.

[0112] Optionally, Span=(D90-D10) / D50=1.5-5.5, and optionally, Span=(D90-D10) / D50=1.5-4.0.

[0113] The Span value of the particle size distribution of cobalt oxyhydroxide is within a suitable range, which can ensure uniform particle size distribution of cobalt oxyhydroxide, avoid the presence of excessively large particles affecting the dispersibility and coating effect of cobalt oxyhydroxide on the surface of the positive electrode material, and also avoid the agglomeration phenomenon caused by excessively small particles, so as to facilitate the improvement of the electrochemical performance of the coated positive electrode material.

[0114] The cobalt oxyhydroxide particles provided in the present application can have a small particle size range and a large specific surface area, and the cobalt oxyhydroxide particles have a nanosheet shape, a nanopoint shape, or both, which comprehensively makes the cobalt oxyhydroxide more easily broken, and in the subsequent combination process with the positive electrode material, the cobalt oxyhydroxide is more easily dispersed and coated on the surface of the positive electrode material, thereby effectively improving the coating effect on the surface of the positive electrode material, so as to significantly improve the performance of the lithium battery.

[0115] In some embodiments of the present application, the specific surface area of the cobalt oxyhydroxide is BET = 40-150 m 2 / g, for example, the specific surface area of the cobalt oxyhydroxide can be 40 m 2 / g, 50 m 2 / g, 60 m 2 / g, 70 m 2 / g, 80 m 2 / g, 90 m 2 / g, 100 m 2 / g, 110 m 2 / g, 120 m 2 / g, 130 m 2 / g, 140 m 2 / g, 150 m 2 / g, or can be any value within 40-110 m 2 / g, 50-115 m 2 / g, 50-80 m 2 / g, 75-120 m 2 / g, 80-140 m 2 / g, 110-150 m 2 / g, etc.

[0116] The high specific surface area of the cobalt oxyhydroxide helps to improve the coverage and dispersibility of the cobalt oxyhydroxide on the surface of the positive electrode material, the resistance of the positive electrode material is small, and the output performance of the coated positive electrode material is effectively improved.

[0117] In some embodiments of the present application, the apparent density AD of the cobalt oxyhydroxide is 0.15-0.42 g / cm 3 ; optionally, AD = 0.15-0.35 g / cm 3For example, the apparent density AD of cobalt oxyhydroxide can be 0.15 g / cm 3 , 0.16 g / cm 3 , 0.17 g / cm 3 , 0.18 g / cm 3 , 0.19 g / cm 3 , 0.20 g / cm 3 , 0.21 g / cm 3 , 0.22 g / cm 3 , 0.23 g / cm 3 , 0.24 g / cm 3 , 0.25 g / cm 3 , 0.26 g / cm 3 , 0.27 g / cm 3 , 0.28 g / cm 3 , 0.29 g / cm 3 , 0.30 g / cm 3 , 0.31 g / cm 3 , 0.32 g / cm 3 , 0.33 g / cm 3 , 0.34 g / cm 3 , 0.35 g / cm 3 , 0.36 g / cm 3 , 0.37 g / cm 3 , 0.38 g / cm 3 , 0.39 g / cm 3 , 0.40 g / cm 3 , 0.41 g / cm 3 , 0.42 g / cm 3 , or can be any value in the range of 0.15-0.19 g / cm 3 , 0.19-0.35 g / cm 3 , 0.19-0.26 g / cm 3 , 0.26-0.31 g / cm 3 , 0.15-0.19 g / cm 3 , 0.31-0.35 g / cm 3 , 0.30-0.40 g / cm 3 , 0.15-0.42 g / cm 3 , etc.

[0118] Within this range of apparent density, it is helpful for cobalt oxyhydroxide to flow and disperse more easily during combination with the positive electrode material, and to effectively improve the dispersibility of cobalt oxyhydroxide on the surface of the positive electrode material.

[0119] In some embodiments of the present application, the cobalt oxyhydroxide particles are nanosheet-like and / or nanodot-like.

[0120] It should be noted that the nanosheet-like in the present embodiment refers to the cobalt oxyhydroxide particles present a thin sheet shape, with a thickness in the nanometer level, and a relatively large surface area, which can provide more active sites, and the cobalt oxyhydroxide is easier to break and disperse during mixing with the positive electrode material, which helps to reduce the agglomeration of the nanoscale cobalt oxyhydroxide particles after breaking and improve the uniformity of the coating on the surface of the positive electrode material; the nanodot-like refers to the cobalt oxyhydroxide particles present a particle shape similar to a sphere or a small cube, with a size in the nanometer level, and a large specific surface area per unit mass, which is conducive to forming a uniform coating layer on the surface of the positive electrode material and improving the electrochemical performance of the positive electrode material after coating; the nanosheet-like and the nanodot-like being intermingled refers to the cobalt oxyhydroxide particles containing both nanosheet-like structure and nanodot-like structure, and the two are intermingled; the cobalt oxyhydroxide with the nanosheet-like and the nanodot-like being intermingled combines the advantages of the nanosheet-like and the nanodot-like structure, which provides a large specific surface area and active sites, and is easy to break, disperse and coat, so as to synergistically improve the coating effect on the positive electrode material and effectively improve the electrochemical performance of the positive electrode material after coating.

[0121] In some embodiments of the present application, the cobalt oxyhydroxide has a chemical formula of aCoOOH.bCo3O4.(1-a-b)Co(OH)2, wherein 0.5≤a≤1, 0≤b≤0.5, 0≤1-a-b≤0.2; for example, a in the chemical formula of the cobalt oxyhydroxide can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0 or can be any value in the range of 0.85-0.90, 0.90-0.95, 0.95-1.0, 0.90-1.0, 0.50-0.60, 0.60-0.70, 0.70-0.85, 0.50-0.85, etc.; b can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.12, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5 or any value in the range of 0-0.02, 0.02-0.06, 0-0.06, 0.02-0.17, 0.17-0.25, 0.25-0.5, etc.; 1-a-b can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2 or any value in the range of 0-0.02, 0.02-0.06, 0-0.1, 0.1-0.2, 0.02-0.20, etc.

[0122] In some embodiments of the present application, the cobalt oxyhydroxide has a chemical formula of xCoOOH.(1-x)Co3O4, wherein 0.85≤x≤1; for example, x in the chemical formula of the cobalt oxyhydroxide can be 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0 or can be any value in the range of 0.85-0.90, 0.90-0.95, 0.95-1.0, 0.90-1.0, etc.

[0123] Optionally, 0.94≤x≤1; it means that the cobalt oxyhydroxide provided in this embodiment can reduce the difficulty of breaking the cobalt oxyhydroxide by controlling the purity of the CoOOH phase, so that the cobalt oxyhydroxide on the surface of the coated positive electrode material can fully react with the residual alkali on the surface of the positive electrode material to generate cobaltate, such as lithium cobaltate generated by reacting with residual lithium, to complete the surface coating of the positive electrode material and improve the overall electrochemical performance of the coated positive electrode material.

[0124] It should be noted that the chemical formula of the cobalt oxyhydroxide in this embodiment is xCoOOH·(1-x)Co3O4, wherein 0.85≤x≤1 or 0.94≤x≤1. For example, the cobalt oxyhydroxide can be pure CoOOH or a combination of CoOOH and Co3O4.

[0125] Another embodiment of the present application provides a preparation method of the above-mentioned cobalt oxyhydroxide, comprising:

[0126] The synthesis process is as follows: a cobalt salt solution, a precipitating agent and an oxidizing agent are added to a base solution to perform a synthesis reaction, and a post-reaction slurry is prepared;

[0127] The post-treatment process is as follows: the post-reaction slurry is post-treated to obtain the cobalt oxyhydroxide;

[0128] During the reaction process of the synthesis process, the feed flow ratio of the cobalt salt solution, the precipitating agent and the oxidizing agent is 1:(0.25-0.80):(0.05-0.60).

[0129] The synthesis process of this embodiment adopts a wet synthesis method. The base solution mainly provides a reaction environment for the synthesis reaction. The cobalt salt solution mainly provides cobalt ions for the synthesis reaction. The precipitating agent can co-precipitate with the cobalt ions under the action of the oxidizing agent to generate a post-reaction slurry containing cobalt hydroxide. Then, the cobalt hydroxide is oxidized into cobalt oxyhydroxide and / or cobalt trioxide tetroxide by the oxidizing agent. Through further post-treatment of the post-reaction slurry in the post-treatment process, the cobalt oxyhydroxide product is obtained.

[0130] It should be noted that in this embodiment, the crystallinity of the cobalt oxyhydroxide is mainly controlled by the feed flow ratio of the cobalt salt solution, the precipitating agent and the oxidizing agent. The feed flow ratio of the cobalt salt solution, the precipitating agent and the oxidizing agent is designed to be 1:(0.25-0.80):(0.05-0.60). Within this feed flow ratio range, the grain size of the (003) crystal plane of the prepared cobalt oxyhydroxide is The grain size of the (003) crystal plane of cobalt oxyhydroxide is small, the particle size range of the particle is small, and the specific surface area is large, so that the cobalt oxyhydroxide is more easily broken, more easily dispersed in the process of combining with the positive material, and coated on the surface of the positive material, thereby effectively improving the coating effect on the surface of the positive material, so as to significantly improve the electrical performance of the lithium battery.

[0131] In addition, the phase composition of cobalt oxyhydroxide is mainly controlled by the feeding ratio of the oxidant. When the feeding flow rate ratio of the cobalt salt solution, the precipitant and the oxidant is in the range of 1:(0.25-0.80):(0.05-0.60), the chemical formula of the prepared cobalt oxyhydroxide is xCoOOH·(1-x)Co3O4, wherein 0.85≤x≤1 or 0.94≤x≤1. When the feeding ratio of the oxidant is in the range of 0.05-0.60, the higher the feeding ratio of the oxidant, the higher the mass ratio of CoOOH phase in the prepared cobalt oxyhydroxide. Correspondingly, when the feeding ratio of the oxidant is less than 0.05, the mass fraction of CoOOH phase in the prepared cobalt oxyhydroxide is less than 0.85, the prepared cobalt oxyhydroxide is difficult to break, is not easy to disperse and coat on the surface of the positive material, and has poor promoting effect on the electrical performance of the lithium battery. When the feeding ratio of the oxidant is greater than 0.60, the intermediate product is easily over-oxidized to generate high-valence cobalt oxide, and too many impurities are easily introduced, so that the prepared cobalt oxyhydroxide has poor quality.

[0132] In the synthesis process of the embodiments of the present application, the feeding flow rate ratio of the cobalt salt solution, the precipitant and the oxidant is 1:(0.25-0.80):(0.05-0.60). For example, the feeding flow rate ratio of the cobalt salt solution, the precipitant and the oxidant can be 1:0.25:0.05, 1:0.35:0.05, 1:0.45:0.05, 1:0.55:0.05, 1:0.65:0.05, 1:0.75:0.05, 1:0.80:0.05, 1:0.25:0.10, 1:0.35:0.15, 1:0.45:0.20, 1:0.55:0.25, 1:0.65:0.30, 1:0.75:0.35, 1:0.80:0.40, 1:0.25:0.45, 1:0.35:0.50, 1:0.45:0.55, 1:0.55:0.60, 1:0.25:0.60, 1:0.80:0.60, 1:0.30:0.50, 1:0.45:0.095, 1:0.45:0.090, 1:0.25:0.40, or any ratio value or ratio range within the ratio range of 1:(0.25-0.80):(0.05-0.60), 1:(0.25-0.45):(0.065-0.50), 1:(0.45-0.80):(0.05-0.065), 1:(0.45-0.80):(0.50-0.60), 1:(0.25-0.45):(0.05-0.065), 1:(0.25-0.45):(0.50-0.60), and the like.

[0133] In some embodiments of the present application, the concentration of hydroxyl ions in the base solution in the synthesis process is 1-6.5 mol / L, and optionally, the concentration of hydroxyl ions in the base solution is 1-3 mol / L. In the present embodiment, the concentration of hydroxyl ions in the base solution is in the range of 1-6.5 mol / L, which can make the intermediate product in the synthesis reaction process have suitable crystallization properties, and help to obtain hydroxyl cobalt oxide with a smaller grain size of (003) crystal face, so that the hydroxyl cobalt oxide is more easily broken, which is beneficial to uniform dispersion and coating on the surface of the positive electrode material. In the present embodiment, the concentration of hydroxyl ions in the base solution can be optionally 1-3 mol / L, and in this range, the (003) crystal face of the obtained hydroxyl cobalt oxide has a smaller grain size, which is beneficial to further improve the breakability of the hydroxyl cobalt oxide, and after coating on the surface of the positive electrode material, the electrochemical performance of the coated positive electrode material is more significantly improved. When the concentration of hydroxyl ions in the base solution is less than 1 mol / L, the synthesis reaction rate is lower, the grain size of the hydroxyl cobalt oxide is too large, and micron-level products are formed, which is not conducive to the preparation of nanometer-level hydroxyl cobalt oxide; when the concentration of hydroxyl ions in the base solution is greater than 6.5 mol / L, the grain size of the (003) crystal face of the obtained hydroxyl cobalt oxide is smaller, and the difficulty of breaking the hydroxyl cobalt oxide particles increases, which cannot realize uniform coating on the positive electrode material.

[0134] In the present embodiment of the present application, the concentration of hydroxyl ions in the base solution in the synthesis process is 1-6.5 mol / L; for example, the concentration of hydroxyl ions in the base solution in the synthesis process can be 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.4 mol / L, 3.6 mol / L, 3.8 mol / L, 4 mol / L, 4.2 mol / L, 4.4 mol / L, 4.6 mol / L, 4.8 mol / L, 5 mol / L, 5.2 mol / L, 5.4 mol / L, 5.6 mol / L, 5.8 mol / L, 6 mol / L, 6.2 mol / L, 6.5 mol / L, or any concentration value or concentration range within the range of 1-6.5 mol / L.

[0135] It should be noted that the base solution in the present embodiment of the present application can be configured by using the above-mentioned precipitating agent, oxidizing agent and water, and the hydroxyl ions in the base solution can be introduced by the precipitating agent, so that the base solution can provide a suitable reaction environment to facilitate the preparation of hydroxyl cobalt oxide with a grain size of (003) crystal face within the range.

[0136] In some embodiments of the present application, the post-processing process specifically includes: sequentially washing, drying and crushing the reaction slurry to obtain hydroxyl cobalt oxide.

[0137] In the embodiments of the present application, the post-processing procedure is to wash, dry and crush the slurry after the reaction. The washing can remove the unreacted raw materials, by-products and solvents and other impurities in the slurry after the reaction to improve the purity of cobalt hydroxyl oxide. The drying can remove the water and volatile solvents in the material after washing. The crushing can break the dried material into smaller particles to improve the specific surface area and reactivity of cobalt hydroxyl oxide and make it have better dispersion and coating performance in application.

[0138] In some embodiments of the present application, the cobalt salt solution includes at least one of cobalt chloride, cobalt sulfate or cobalt nitrate. All of the above substances can be used as a cobalt salt solution to provide a cobalt source for the synthesis reaction to prepare cobalt hydroxyl oxide with a smaller grain size of (003) crystal face.

[0139] In some embodiments of the present application, the precipitant includes at least one of potassium hydroxide solution or sodium hydroxide solution. All of the above substances as a precipitant can rapidly react with cobalt ions in the cobalt salt solution to generate cobalt-containing precipitates during the synthesis reaction, which helps to prepare cobalt hydroxyl oxide with a smaller grain size of (003) crystal face.

[0140] In some embodiments of the present application, the oxidizing agent includes at least one of hydrogen peroxide, sodium hypochlorite, sodium persulfate or ammonium persulfate. All of the above substances as an oxidizing agent have strong oxidizing ability, which helps to control the rate of the synthesis reaction process and makes the phase composition of cobalt hydroxyl oxide more easily controlled.

[0141] In some embodiments of the present application, the mass concentration of cobalt ions in the cobalt salt solution is 1-3 mol / L. The appropriate mass concentration of cobalt ions in the cobalt salt solution helps to control the synthesis reaction to prepare cobalt hydroxyl oxide with a smaller grain size of (003) crystal face.

[0142] In some embodiments of the present application, the mass fraction of solute in the precipitant is 28-36 wt%. The mass fraction of solute in the precipitant is in an appropriate range, which helps to control the synthesis reaction to prepare cobalt hydroxyl oxide with a smaller grain size of (003) crystal face.

[0143] In some embodiments of the present application, the mass fraction of solute in the oxidizing agent is 25-30 wt%. The mass fraction of solute in the oxidizing agent is in an appropriate range, which helps to control the synthesis reaction to prepare cobalt hydroxyl oxide with a smaller grain size of (003) crystal face.

[0144] In some embodiments of the present application, the synthesis process is carried out in a reaction container, and the flow rate of the cobalt salt solution is 5-25% of the volume of the reaction container per hour. Within this range, the flow rate of the cobalt salt solution helps to regulate the synthesis reaction to produce cobalt hydroxide with a smaller grain size of the (003) crystal face. Here, the flow rate refers to the amount of the cobalt salt solution flowing into the reaction container per unit time. For example, if the volume of the reaction container is 100 ml, the flow rate of the cobalt salt solution is 5-25 ml per hour. 3 Therefore, if the flow rate of the cobalt salt solution is 5% of the volume of the reaction container per hour, the flow rate of the cobalt salt solution is 5 ml per hour. 3 .

[0145] In some embodiments of the present application, the synthesis process is carried out in a reaction container, and the reaction is terminated when the volume of the materials in the reaction container reaches 70-90% of the volume of the reaction container. When the volume of the materials in the reaction container reaches 70-90% of the volume of the reaction container, it means that the reaction has reached a relatively sufficient stage, and the reaction is terminated at this time to ensure that most of the reactants have been converted into the target product, thereby avoiding the generation of by-products due to excessive synthesis reaction, and ensuring the product quality and purity of the cobalt hydroxide produced.

[0146] In some embodiments of the present application, the reaction temperature of the synthesis process is controlled to be 35-70°C, which can ensure the reaction rate of the synthesis reaction and make the grain size D (003) of the (003) crystal face of the cobalt hydroxide prepared within the range of .

[0147] In some embodiments of the present application, the synthesis reaction is carried out under stirring, and the stirring rate is controlled to be 240-500 r / min. For example, the stirring rate of the synthesis reaction can be 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min, 300 r / min, 310 r / min, 320 r / min, 330 r / min, 340 r / min, 350 r / min, 360 r / min, 370 r / min, 380 r / min, 390 r / min, 400 r / min, 410 r / min, 420 r / min, 430 r / min, 440 r / min, 450 r / min, 460 r / min, 470 r / min, 480 r / min, 490 r / min, 500 r / min, or any value within the range of 240-400 r / min or 400-500 r / min. The stirring of the synthesis reaction can ensure that the raw materials are fully mixed during the synthesis reaction, which helps to achieve uniform reaction between the cobalt salt solution, the precipitating agent, and the oxidizing agent, and avoids the problem of uneven reaction caused by excessively high or low local concentration.

[0148] In some embodiments of the present application, in the post-processing procedure, when the drying treatment is performed, the temperature of the drying is 120-140°C, and the drying time is controlled to be 15-25h, so as to ensure that the moisture and the volatile solvent in the material are fully removed, thereby improving the product quality and purity of the finally prepared cobalt oxyhydroxide.

[0149] In some embodiments of the present application, in the post-processing procedure, when the crushing treatment is performed, the crushing equipment can be, for example, a XX disc nest mill or a XX jet mill, wherein “XX” can be any specific brand, specification, model or customized name.

[0150] Another embodiment of the present application further provides a positive electrode material, wherein the coating material of the positive electrode material or the raw material of the coating material of the positive electrode material comprises the cobalt oxyhydroxide as described above, and the amount of the cobalt oxyhydroxide is 1-5wt% of the mass of the positive electrode material.

[0151] In some embodiments, the positive electrode material is a lithium-mixed positive electrode material, which can be prepared, for example, by mixing and sintering the cobalt oxyhydroxide with a nickel-cobalt-manganese (NCM) positive electrode material or a lithium manganate (LMO) positive electrode material or a sodium positive electrode material (laminated oxide, Prussian blue / white compound, polyanion, etc.), i.e., mixing the cobalt oxyhydroxide as described above with the lithium-mixed positive electrode material after the first sintering, and then performing the second sintering treatment in an air or oxygen atmosphere, and then crushing and sieving the product obtained after the sintering treatment to obtain the positive electrode material.

[0152] Another embodiment of the present application further provides a battery comprising the positive electrode material as described above, wherein the battery is a lithium ion battery or a sodium ion battery. For example, the positive electrode material, conductive carbon black and a binder are mixed and coated on an aluminum foil to obtain a positive electrode sheet; and the battery shell, the positive electrode sheet, the negative electrode sheet, the separator, the spring and the gasket are assembled to obtain the battery.

[0153] Another embodiment of the present application further provides an electrical equipment comprising the battery as described above.

[0154] The following examples more specifically describe the disclosure of the present application, which are merely illustrative and various modifications and changes can be made within the scope of the disclosure of the present application, which will be apparent to those skilled in the art. Unless otherwise stated, all reagents and raw materials used in the examples are commercially available or are synthesized according to conventional methods, and the instruments used in the examples are commercially available.

[0155] Example 1

[0156] The chemical formula of the cobalt oxyhydroxide is CoOOH, and the preparation process is as follows:

[0157] Synthesis process: the mixed solution of pure water and sodium hydroxide solution is used as the bottom solution, the concentration of hydroxide ion in the bottom solution is controlled to be 3.0 mol / L; the bottom solution is added into a reaction container, stirring is started, the stirring speed is 300 rpm, a cobalt content of 2.0 mol / L cobalt chloride solution, a mass concentration of 32 wt% sodium hydroxide solution and a mass concentration of 27.5 wt% hydrogen peroxide are added into the bottom solution for synthesis reaction, the liquid volume ratio of cobalt chloride solution, sodium hydroxide solution and hydrogen peroxide is 1:0.30:0.50, the flow rate of cobalt chloride solution is 11.8-12.2% of the volume of the reaction container per hour, the synthesis reaction temperature is controlled to be 40°C, the reaction is ended when the volume of the reaction container is 80%, and a post-reaction slurry is obtained.

[0158] Post-processing process: the post-reaction slurry is washed with hot water for 3 times, then pressure filtration is performed, the post-pressure filtration material is dried at a temperature of 130°C for 20 hours to obtain a dried material, and the dried material is crushed by using an air flow mill to obtain cobalt oxyhydroxide. As shown in FIGS. 1 and 2, the particles of the cobalt oxyhydroxide prepared in Example 1 are mainly in the morphology of nanosheet layer and nanodot interlaced, and the particles are mainly in the form of nanosheet layer; as shown in FIG. 10, the main peaks of the XRD pattern of the cobalt oxyhydroxide prepared in Example 1 match with the Heterogenite (CoOOH) in the PDF card, and no Co3O4 characteristic peak in the PDF card is found, and the phase composition is analyzed by using Japanese science software, combined with the Co% content data, it is obtained that the chemical formula of the cobalt oxyhydroxide prepared in Example 1 is CoOOH; as shown in FIG. 18, the surface of the positive electrode material prepared from the cobalt oxyhydroxide prepared in Example 1 is smooth, which indicates that the cobalt oxyhydroxide has good coating performance, and the cobalt oxyhydroxide is melted on the surface of the positive electrode material after secondary sintering.

[0159] Example 2

[0160] The chemical formula of the cobalt oxyhydroxide is 0.98CoOOH·0.02Co3O4, and the preparation process is as follows:

[0161] Synthesis process: the mixed solution of pure water, sodium hydroxide solution and sodium persulfate is used as the bottom solution, the concentration of hydroxide ion in the bottom solution is controlled to be 2.0 mol / L, and the concentration of persulfate ion is controlled to be 0.28 mol / L; the bottom solution is added into a reaction container, stirring is started, the stirring speed is 300 rpm, a cobalt content of 2.0 mol / L cobalt sulfate solution, a mass concentration of 32 wt% sodium hydroxide solution and a mass concentration of 27.5 wt% hydrogen peroxide are added into the bottom solution for synthesis reaction, the liquid volume ratio of cobalt sulfate solution, sodium hydroxide solution and hydrogen peroxide is 1:0.45:0.095, the flow rate of cobalt sulfate solution is 19.8-20.2% of the volume of the reaction container per hour, the synthesis reaction temperature is controlled to be 50°C, the reaction is ended when the volume of the reaction container is 80%, and a post-reaction slurry is obtained.

[0162] Post-processing procedure: The reaction slurry is washed with hot water for 3 times, and then is filtered under pressure. The filtered material is dried at 130°C for 20h, and then is crushed by a disc nest grinder to obtain cobalt oxyhydroxide. As shown in FIG. 3, the cobalt oxyhydroxide prepared in Example 2 has a morphology mainly of nanosheet layer and nanodot interlayer, and the nanodot is the majority. As shown in FIG. 11, the main peaks of the XRD pattern of the cobalt oxyhydroxide prepared in Example 2 match the Heterogenite (CoHO2) in the PDF card, and contains a trace of Co3O4 characteristic peaks in the PDF card. According to the phase composition analyzed by the Japan Science software and the Co% content data, the chemical formula of the cobalt oxyhydroxide prepared in Example 2 is 0.98CoOOH·0.02Co3O4. As shown in FIG. 19, the surface of the positive electrode material prepared from the cobalt oxyhydroxide prepared in Example 2 is smooth, indicating that the cobalt oxyhydroxide has good coating performance, and the cobalt oxyhydroxide is melted on the surface of the positive electrode material after secondary sintering.

[0163] Example 3

[0164] The cobalt oxyhydroxide has a chemical formula of 0.94CoOOH·0.06Co3O4, and is prepared as follows:

[0165] Synthesis procedure: A mixed solution of pure water, sodium hydroxide solution and sodium persulfate is used as the bottom solution, the concentration of hydroxide ions in the bottom solution is controlled to be 2.0 mol / L, and the concentration of persulfate ions is controlled to be 0.35 mol / L. The bottom solution is added to a reaction container, and stirring is started with a stirring speed of 300 rpm. A cobalt sulfate solution with a cobalt content of 2.0 mol / L, a sodium hydroxide solution with a mass concentration of 32 wt%, and hydrogen peroxide with a mass concentration of 27.5 wt% are added to the bottom solution for synthesis reaction. The volume ratio of the cobalt sulfate solution, the sodium hydroxide solution and the hydrogen peroxide is 1:0.45:0.090. The flow rate of the cobalt sulfate solution is 19.8-20.2% of the volume of the reaction container per hour. The synthesis reaction is carried out at a temperature of 60°C, and is completed when 80% of the volume of the reaction container is filled. A reaction slurry is obtained.

[0166] Post-processing procedure: the reaction slurry is washed with hot water for 3 times, then filtered under pressure, the filtered material is dried at 130°C for 20h, the dried material is pulverized by air jet mill to obtain cobalt oxyhydroxide. As shown in Figure 4, the cobalt oxyhydroxide prepared in Example 3 has a morphology mainly of nanosheet layer and nanodot interlaced; as shown in Figure 12, the main peaks of the XRD pattern of the cobalt oxyhydroxide prepared in Example 3 match with Heterogenite (CoHO2) in the PDF card, and contain a trace of Co3O4 characteristic peaks in the PDF card, and the phase composition is calculated by Japan Science software analysis combined with Co% content data: the chemical formula of the cobalt oxyhydroxide prepared in Example 3 is 0.94CoOOH·0.06Co3O4; as shown in Figure 20, the surface of the positive electrode material prepared from the cobalt oxyhydroxide prepared in Example 3 is rough, a small amount of small particles are individually floating or free on the surface of the positive electrode material, and a very small amount of large particles are aggregated and floating or free on the surface of the positive electrode material, indicating that the hydroxide coating performance is good, and most of the hydroxide is melted to the surface of the positive electrode material after secondary sintering.

[0167] Example 4

[0168] The cobalt oxyhydroxide has a chemical formula of CoOOH, and its preparation process is as follows:

[0169] Synthesis procedure: a mixed solution of pure water and sodium hydroxide solution is used as the bottom liquid, and the concentration of hydroxide ions in the bottom liquid is controlled to be 6.5 mol / L; the bottom liquid is added to the reaction container, and stirring is started with a stirring speed of 300 rpm; a cobalt chloride solution with a cobalt content of 2.0 mol / L, a sodium hydroxide solution with a mass concentration of 32 wt%, and a hydrogen peroxide solution with a mass concentration of 27.5 wt% are added to the bottom liquid for synthesis reaction, and the liquid volume ratio of the cobalt chloride solution, the sodium hydroxide solution, and the hydrogen peroxide solution is 1:0.25:0.40; the flow rate of the cobalt chloride solution is 11.8-12.2% of the volume of the reaction container per hour; the synthesis reaction is carried out at a temperature of 35°C; the reaction is stopped when the volume of the reaction container is 80%; and a reaction slurry is obtained.

[0170] Post-processing procedure: the reaction slurry is washed with hot water for 2 times, then filtered under pressure, the filtered material is dried at 130℃ for 20h, the dried material is pulverized by air jet mill to obtain cobalt oxyhydroxide. As shown in Figure 5, the cobalt oxyhydroxide prepared in Example 4 has a morphology mainly of nanosheet layer and nanodot interlaced; as shown in Figure 13, the main peaks of the XRD pattern of the cobalt oxyhydroxide prepared in Example 4 match with Heterogenite (CoHO2) in the PDF card, and no Co3O4 characteristic peak in the PDF card is observed, the phase composition is analyzed by Japan Science software, combined with Co% content data, it is calculated that: the chemical formula of the cobalt oxyhydroxide prepared in Example 4 is CoOOH; as shown in Figure 21, the surface of the positive electrode material prepared from the cobalt oxyhydroxide prepared in Example 4 is rough, and a small amount of small particles are separately in the form of small balls floating on or free from the surface of the positive electrode material, indicating that the cobalt oxyhydroxide has good coating performance.

[0171] Example 5

[0172] The cobalt oxyhydroxide has a chemical formula of 0.83CoOOH·0.17Co3O4, and its preparation process is as follows:

[0173] Synthesis procedure: pure water, sodium hydroxide solution and mixed solution of sodium persulfate are used as the bottom liquid, the concentration of hydroxide ion in the bottom liquid is controlled to be 4.5mol / L, and the concentration of persulfate ion is controlled to be 0.40mol / L; the bottom liquid is added into a reaction container, stirring is started, the stirring speed is 300rpm, 2.0mol / L cobalt sulfate solution, 32wt% sodium hydroxide solution and 27.5wt% hydrogen peroxide solution are added into the bottom liquid for synthesis reaction, the volume ratio of the liquid of cobalt sulfate solution, sodium hydroxide solution and hydrogen peroxide solution is 1:0.45:0.075, the flow rate of the cobalt sulfate solution is 19.8-20.2% of the volume of the reaction container per hour, the synthesis reaction temperature is controlled to be 80℃, the reaction is ended when the volume of the reaction container is 80%, and the reaction slurry is obtained.

[0174] Post-processing procedure: the reaction slurry is washed with hot water for 2 times, then filtered under pressure, the filtered material is dried at 130℃ for 20h, the dried material is pulverized by air jet mill to obtain cobalt oxyhydroxide. As shown in FIG. 6, the cobalt oxyhydroxide prepared in Example 5 has a morphology mainly of nanosheet layer and nanodot interlaced; as shown in FIG. 14, the main peaks of the XRD pattern of the cobalt oxyhydroxide prepared in Example 5 match with the Heterogenite (CoHO2) in the PDF card, and contain a small amount of Co3O4 characteristic peaks in the PDF card, and the phase composition is calculated by Japan Science software analysis combined with Co% content data: the chemical formula of the cobalt oxyhydroxide prepared in Example 5 is 0.83CoOOH·0.17Co3O4; as shown in FIG. 22, the surface of the positive electrode material prepared from the cobalt oxyhydroxide prepared in Example 5 is rough, and a small amount of small particles are individually floating or free on the surface of the positive electrode material, indicating that the cobalt oxyhydroxide has good coating performance.

[0175] Example 6

[0176] The cobalt oxyhydroxide has a chemical formula of 0.60CoOOH·0.30Co3O4·0.10Co(OH)2, and its preparation process is as follows:

[0177] Synthesis procedure: a mixed solution of pure water, sodium hydroxide solution and sodium persulfate is used as the bottom liquid, the concentration of hydroxide ions in the bottom liquid is controlled to be 4.5mol / L, and the concentration of persulfate ions is controlled to be 0.28mol / L; the bottom liquid is added into a reaction container, stirring is started, the stirring speed is 300rpm, a cobalt sulfate solution with a cobalt content of 2.0mol / L, a sodium hydroxide solution with a mass concentration of 32wt%, and hydrogen peroxide with a mass concentration of 27.5wt% are added into the bottom liquid for synthesis reaction, the volume ratio of the cobalt sulfate solution, the sodium hydroxide solution and the hydrogen peroxide is 1:0.45:0.065, the flow rate of the cobalt sulfate solution is 19.8-20.2% of the volume of the reaction container per hour, the synthesis reaction is controlled at a temperature of 70℃, and the reaction is ended when 80% of the volume of the reaction container is filled, to obtain a reaction slurry.

[0178] Post-processing procedure: the reaction slurry is washed with hot water for 2 times, then is subjected to pressure filtration, the obtained material after pressure filtration is dried at a temperature of 130°C for 20h, the dried material is subjected to pulverization treatment with an air flow mill, and cobalt oxyhydroxide is obtained. As shown in FIG. 7, the particles of cobalt oxyhydroxide prepared in Example 6 are mainly in the morphology of nanosheet layer interlaced with nanodots; as shown in FIG. 15, the main peaks of the XRD pattern of cobalt oxyhydroxide prepared in Example 6 match with the Heterogenite (CoOOH) in the PDF card, and contain a small amount of Co3O4 characteristic peaks in the PDF card and a small amount of Cobalt hydroxide (Co(OH)2) characteristic peaks in the PDF card, and the phase composition is calculated by Japanese science software analysis combined with Co% content data: the chemical formula of cobalt oxyhydroxide prepared in Example 6 is 0.60CoOOH·0.30Co3O4·0.10Co(OH)2; as shown in FIG. 23, the surface of the positive electrode material prepared from the cobalt oxyhydroxide prepared in Example 6 is rough, and a small amount of small particles are separately in the form of small balls floating on or free from the surface of the positive electrode material, indicating that the cobalt oxyhydroxide has good coating performance.

[0179] Example 7

[0180] The cobalt oxyhydroxide has a chemical formula of CoOOH, and its preparation process is as follows:

[0181] Synthesis procedure: a mixed solution of pure water, sodium hydroxide solution and sodium persulfate is used as a bottom solution, the concentration of hydroxide ions in the bottom solution is controlled to be 3.5 mol / L, and the concentration of persulfate ions is controlled to be 0.40 mol / L; the bottom solution is added into a reaction container, stirring is started, the stirring speed is 300 rpm, a cobalt sulfate solution with a cobalt content of 2.0 mol / L, a sodium hydroxide solution with a mass concentration of 32wt%, and hydrogen peroxide with a mass concentration of 27.5wt% are added into the bottom solution for synthesis reaction, the volume ratio of the cobalt sulfate solution, the sodium hydroxide solution and the hydrogen peroxide is 1:0.45:0.070, the flow rate of the cobalt sulfate solution is 19.8-20.2% of the volume of the reaction container per hour, the synthesis reaction is controlled at a temperature of 70°C, and the reaction is ended when 80% of the volume of the reaction container is filled, and a reaction slurry is obtained.

[0182] Post-processing procedure: the reaction slurry is washed with hot water for 2 times, then is subjected to pressure filtration, the obtained material after pressure filtration is dried at a temperature of 130°C for 20h, the dried material is subjected to pulverization treatment with an air flow mill, and cobalt oxyhydroxide is obtained. The chemical formula of the cobalt oxyhydroxide prepared in Example 7 is 0.86CoOOH·0.14Co3O4; the cobalt oxyhydroxide prepared in Example 7 is mixed with the positive electrode sintered material to prepare a positive electrode material, and performance evaluation is carried out.

[0183] Example 8

[0184] The chemical formula of cobalt oxyhydroxide is CoOOH, and the preparation process is as follows:

[0185] The synthesis process is as follows: a mixed solution of pure water, sodium hydroxide solution and sodium persulfate is used as the bottom solution, the concentration of hydroxide ions in the bottom solution is controlled to be 2.0 mol / L, and the concentration of persulfate ions is controlled to be 0.30 mol / L; the bottom solution is added to a reaction container, stirring is started, the stirring speed is 300 rpm, a cobalt sulfate solution with a cobalt content of 2.0 mol / L, a sodium hydroxide solution with a mass concentration of 32 wt%, and hydrogen peroxide with a mass concentration of 27.5 wt% are added to the bottom solution for synthesis reaction, the volume ratio of the inlet liquid of the cobalt sulfate solution, the sodium hydroxide solution, and the hydrogen peroxide is 1:0.40:0.100, the flow rate of the cobalt sulfate solution is 19.8-20.2% of the volume of the reaction container per hour, the synthesis reaction temperature is controlled to be 70°C, and the reaction is stopped when the volume of the reaction container is 80%, to obtain the reaction slurry.

[0186] The post-processing process is as follows: the reaction slurry is washed with hot water for 2 times, then pressure filtration is performed, the material after pressure filtration is dried at a temperature of 130°C for 20 hours to obtain dried material, and the dried material is crushed by using an air flow mill to obtain cobalt oxyhydroxide. The chemical formula of the cobalt oxyhydroxide prepared in Example 8 is 0.90CoOOH·0.10Co3O4; the cobalt oxyhydroxide prepared in Example 8 is mixed with the positive electrode sintered material to prepare a positive electrode material, and performance evaluation is performed.

[0187] Comparative Example 1

[0188] The chemical formula of cobalt oxyhydroxide is CoOOH, and the preparation process is as follows:

[0189] The synthesis process is as follows: a mixed solution of pure water, sodium hydroxide solution and sodium persulfate is used as the bottom solution, the concentration of hydroxide ions in the bottom solution is controlled to be 4.5 mol / L, and the concentration of persulfate ions is controlled to be 0.45 mol / L; the bottom solution is added to a reaction container, stirring is started, the stirring speed is 300 rpm, a cobalt sulfate solution with a cobalt content of 2.0 mol / L, a sodium hydroxide solution with a mass concentration of 32 wt%, and hydrogen peroxide with a mass concentration of 27.5 wt% are added to the bottom solution for synthesis reaction, the volume ratio of the inlet liquid of the cobalt sulfate solution, the sodium hydroxide solution, and the hydrogen peroxide is 1:0.45:0.095, the flow rate of the cobalt sulfate solution is 19.8-20.2% of the volume of the reaction container per hour, the synthesis reaction temperature is controlled to be 70°C, and the reaction is stopped when the volume of the reaction container is 80%, to obtain the reaction slurry.

[0190] Post-processing procedure: the reaction slurry is washed with hot water for 2 times, then filtered under pressure, the obtained material after pressure filtration is dried at 130℃ for 20h, the dried material is then pulverized by air jet mill to obtain cobalt oxyhydroxide. As shown in FIG. 8, the particles of cobalt oxyhydroxide prepared in Comparative Example 1 are mainly in the morphology of nanosheet layer and nanodot interlaced; as shown in FIG. 16, the main peaks of the XRD pattern of cobalt oxyhydroxide prepared in Comparative Example 1 match with Heterogenite (CoHO2) in the PDF card, and contain a small amount of Co3O4 characteristic peaks in the PDF card and a small amount of Cobalt hydroxide (Co(OH)2) characteristic peaks in the PDF card, and the phase composition is calculated by Japan Science software analysis combined with Co% content data: the chemical formula of cobalt oxyhydroxide prepared in Comparative Example 1 is CoOOH; as shown in FIG. 24, the surface of the positive electrode material prepared from the cobalt oxyhydroxide prepared in Comparative Example 1 is rough, and there are a large number of small particles floating on or free from the surface of the positive electrode material in the form of small balls, and a small amount of large particles floating on or free from the surface of the positive electrode material in the form of agglomeration, indicating that the cobalt oxyhydroxide coating performance is poor, and part of the cobalt oxyhydroxide is not melted to the surface of the positive electrode material after secondary sintering.

[0191] Comparative Example 2

[0192] The chemical formula of cobalt oxyhydroxide is 0.85CoOOH·0.15Co3O4, and the preparation process is as follows:

[0193] Synthesis procedure: a mixed solution of pure water and a sodium hydroxide solution with a mass concentration of 32wt% is used as a bottom solution, and the concentration of hydroxide ions in the bottom solution is controlled to be 3.0mol / L; the bottom solution is added to a reaction container, stirring is started, the stirring speed is 300rpm, a cobalt chloride solution with a cobalt content of 2.0mol / L, a sodium hydroxide solution with a mass concentration of 32wt%, and a hydrogen peroxide solution with a mass concentration of 27.5wt% are added to the bottom solution for synthesis reaction, the liquid volume ratio of the cobalt chloride solution, the sodium hydroxide solution, and the hydrogen peroxide solution is 1:0.38:0.33, the flow rate of the cobalt chloride solution is 19.8-20.2% of the volume of the reaction container per hour, the synthesis reaction temperature is controlled to be 80℃, and the reaction is ended when 80% of the volume of the reaction container is reacted, to obtain a reaction slurry.

[0194] Post-processing step: After the reaction slurry is washed with hot water for 2 times, the obtained material after pressure filtration is dried at a temperature of 100°C for 28h, and the dried material is subjected to a jet mill for crushing treatment to obtain cobalt oxyhydroxide. As shown in FIG. 9, the cobalt oxyhydroxide prepared in Comparative Example 2 has a spherical morphology as a whole; as shown in FIG. 17, the main peaks of the XRD pattern of the cobalt oxyhydroxide prepared in Comparative Example 2 match the Heterogenite (CoHO2) in the PDF card, and a small amount of Co3O4 characteristic peaks in the PDF card are contained. According to the phase composition analyzed by the Japan Science software and the Co% content data, the chemical formula of the cobalt oxyhydroxide prepared in Comparative Example 2 is 0.85CoOOH·0.15Co3O4.

[0195] The key preparation parameters of the cobalt oxyhydroxide prepared in Examples 1-8 and Comparative Examples 1-2 above are statistically analyzed, and the results are shown in Table 1 below:

[0196] Table 1: Statistical table of key preparation parameters of cobalt oxyhydroxide Note: The feed flow ratio in Table 1 above refers to the feed flow ratio of cobalt salt solution, precipitant and oxidant during the synthesis reaction process of each example and comparative example.

[0197] The cobalt oxyhydroxide prepared in Examples 1-8 and Comparative Examples 1-2 above is tested and characterized respectively, and the test data of the cobalt oxyhydroxide are obtained, and the statistical data are shown in Table 1 below:

[0198] Table 2: Physical and chemical data table of cobalt oxyhydroxide

[0199] Preparation of positive electrode materials of Examples 1-8, Comparative Examples 1-2 and control group

[0200] Further, the cobalt oxyhydroxide prepared in Examples 1-8 and Comparative Examples 1-2 above is coated on the surface of the positive electrode material to prepare a positive electrode material, and the preparation process is as follows:

[0201] The cobalt oxyhydroxide prepared in Examples 1-8 and Comparative Example 1 is taken and mixed with the once-fired lithium-mixed positive electrode material at a mass ratio of 2% for 40 min, and then the obtained mixture is twice-fired at 650°C for 8h. The fired material obtained after the twice-firing is subjected to cooling, crushing and sieving treatment in sequence to obtain a positive electrode material.

[0202] Preparation of positive electrode material of control group: blank sample without coating

[0203] In order to verify the electrical performance advantages of the coated positive electrode material of the present application, the lithium-mixed positive electrode material prepared by the above primary sintering is directly sintered for 8 h at 650 ℃ without coating, and the sintered material obtained by the secondary sintering is sequentially subjected to cooling, crushing and sieving to obtain a control group positive electrode material.

[0204] The positive electrode materials prepared from the hydroxyl cobalt oxide of Examples 1-8 and Comparative Example 1 and the control group are characterized under a scanning electron microscope, and the obtained SEM photos are shown in Figures 18-25, respectively.

[0205] It should be noted that the hydroxyl cobalt oxide prepared in Comparative Example 2 is a micron-sized particle with a particle size D50 of 1.71 μm, which is not a nano-sized particle and cannot achieve coating of the positive electrode material, so the positive electrode material prepared therefrom is not subjected to SEM characterization test and electrochemical test.

[0206] In order to verify the influence of the hydroxyl cobalt oxide on the electrochemical performance of the lithium battery, the positive electrode materials prepared from the hydroxyl cobalt oxide in Examples 1-8 above and the positive electrode material group without coating in the control group are respectively assembled into button cells, and the electrical performance test is carried out. The button cell preparation process and test conditions are as follows; it should be noted that the electrochemical evaluation is not carried out due to the poor coating effect of Comparative Example 1.

[0207] The positive electrode materials prepared from the hydroxyl cobalt oxide in Examples 1-8 and the control group above are respectively mixed with a conductive agent and a binder PVDF in a predetermined ratio to form a slurry, which is coated on an aluminum foil to form a positive electrode sheet. The negative electrode sheet is a metal lithium sheet, the electrolyte is 1 mol / L LiPF6 / EC:DMC (volume ratio 1:1), and the battery shell, positive and negative electrode sheets, separator, spring and gasket are assembled into a button cell in a vacuum glove box.

[0208] The electrochemical performance of the button cells prepared above is respectively tested, the test temperature is 25 ℃, the test voltage range is 3.0-4.35 V, and 1C=180 mAh / g; the test results obtained by the test are shown in the following Table 3:

[0209] Table 3: Statistical table of electrochemical performance test data

[0210] It should be noted that in Table 3, 1C 50 th The capacity retention rate represents the capacity retention rate after 50 weeks of cycling at 1C; DCIR is the direct current resistance.

[0211] The advantages of the present application are analyzed as follows in combination with Tables 1-3 and Figures 1-25:

[0212] Compared with Comparative Example 2, the concentration of hydroxyl ions in the bottom solution in the synthesis process of Example 1 is 3 mol / L, which is in the range of 1-6.5 mol / L, and the grain size D of the (003) crystal plane of the prepared cobalt oxyhydroxide is (003) For The grain size of the (003) crystal plane is small, the half-peak width FWHM(003) of the diffraction peak corresponding to the (003) crystal plane in the XRD spectrum is 0.431°, which is beneficial to improve the crushing effect of the cobalt oxyhydroxide, the average particle size D50 of the crushed cobalt oxyhydroxide is 0.146 μm, which is in the nanometer level, and the dispersion performance and coating performance after mixing with the positive electrode material can be improved, the surface of the coated positive electrode material is very smooth (as shown in FIG. 18), and the electrochemical performance of the battery prepared by the coated positive electrode material is improved. In contrast, in Comparative Example 2, the concentration of hydroxyl ions in the bottom solution in the synthesis process is 0.8 mol / L, which is too low, and the grain size D of the (003) crystal plane of the prepared cobalt oxyhydroxide is (003) For The grain size of the (003) crystal plane is too large, the cobalt oxyhydroxide is in the form of micron-level spherical particles, which is not easy to crush and cannot be coated on the surface of the positive electrode material; thus, it is verified that the grain size D of the (003) crystal plane of the cobalt oxyhydroxide (003) For is in the range of 1-6.5 mol / L, which is beneficial to the crushed cobalt oxyhydroxide to have a large specific surface area and a small particle size, so that the cobalt oxyhydroxide has excellent crushing effect, and the dispersion performance and coating performance of the cobalt oxyhydroxide as an additive material when mixed with the positive electrode material are better. As can be seen from Table 3, the 0.1C charge capacity, 0.1C discharge capacity, 0.1C coulombic efficiency, 1C 50 th capacity retention rate, 1.0C / 0.25C rate, 2.0C / 0.25C rate, and other performances of Example 1 are all better, and the resistance after 1C 50 th cycle is lower.

[0213] The present application designs the structure of the cobalt oxyhydroxide and its preparation method, and the grain size of the (003) crystal plane of the cobalt oxyhydroxide is in the range of 1-6.5 mol / L, which is beneficial to the crushed cobalt oxyhydroxide to have a large specific surface area and a small particle size, so that the cobalt oxyhydroxide has excellent crushing effect, and the dispersion performance and coating performance of the cobalt oxyhydroxide as an additive material when mixed with the positive electrode material are better. As can be seen from Table 3, the 0.1C charge capacity, 0.1C discharge capacity, 0.1C coulombic efficiency, 1C 50 th capacity retention rate, 1.0C / 0.25C rate, 2.0C / 0.25C rate, and other performances of Example 1 are all better, and the resistance after 1C 50 th cycle is lower.

[0213] The present application designs the structure of the cobalt oxyhydroxide and its preparation method, and the grain size of the (003) crystal plane of the cobalt oxyhydroxide

[0214] Any of the technical features described above can be combined. Although not all possible combinations of the technical features are described, any combination of the technical features should be considered as being covered by the present specification, as long as such a combination does not result in a contradiction.

[0215] Finally, it should be noted that the above-described embodiments are merely intended to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. Cobalt oxyhydroxide characterized in that, In the XRD pattern of the cobalt oxyhydroxide, the cobalt oxyhydroxide has a grain size of 100 nm or more at a (003) crystal face The (003) crystal face corresponds to a diffraction peak at a diffraction angle 2θ of 19° to 21°.

2. Cobalt oxyhydroxide according to claim 1, characterized in that The cobalt oxyhydroxide satisfies at least one of the following conditions: A. the cobalt oxyhydroxide has a grain size of (003) crystal plane Optionally, B. In the XRD pattern of the cobalt oxyhydroxide, the half-peak width FWHM(003) of the diffraction peak corresponding to the (003) crystal face is 0.29°-0.84°; optionally, the FWHM(003) is 0.29°-0.53°; optionally, the FWHM(003) is 0.35°-0.53°; C. The mass fraction of alkali metal in the cobalt oxyhydroxide is ≤70 ppm; optionally, the mass fraction of alkali metal in the cobalt oxyhydroxide is 10-65 ppm; D. The average particle size D50 of the cobalt oxyhydroxide is ≤0.22 μm; optionally, the D50 is ≤0.16 μm; optionally, 0.11 μm≤D50≤0.16 μm.

3. Cobalt oxyhydroxide according to claim 1 or 2, characterized in that The cobalt oxyhydroxide satisfies at least one of the following conditions: F. The particle size D10 of the cobalt oxyhydroxide is ≤0.090 μm; optionally, 0.06 μm≤D10≤0.09 μm; G. The particle size D90 of the cobalt oxyhydroxide is ≤2.1 μm; optionally, the D90 is ≤1.3 μm; optionally, 0.2 μm≤D90≤0.80 μm; H. The particle size distribution Span=(D90-D10) / D50 of the cobalt oxyhydroxide is 1-10; optionally, the Span=(D90-D10) / D50 is 1.5-5.5; I. The mass fraction of Cl in the cobalt oxyhydroxide is ≤300 ppm; optionally, the mass fraction of Cl in the cobalt oxyhydroxide is ≤200 ppm; J. The mass fraction of S in the cobalt oxyhydroxide is ≤600 ppm; optionally, the mass fraction of S in the cobalt oxyhydroxide is ≤300 ppm.

4. Cobalt oxyhydroxide according to any one of claims 1 to 3, characterized in that The cobalt oxyhydroxide satisfies at least one of the following conditions: K, the specific surface area BET of the cobalt oxyhydroxide is comprised between 40 and 150 m 2 / g; L, the apparent density AD of the cobalt oxyhydroxide is 0.15-0.42 g / cm 3 ; optionally, AD = 0.15-0.35 g / cm 3 ; M. The particles of the cobalt oxyhydroxide are nanosheet layer-shaped and / or nanodot-shaped; N. The chemical formula of the cobalt oxyhydroxide is aCoOOH·bCo3O4·(1-a-b)Co(OH)2, wherein 0.5≤a≤1, 0≤b≤0.5, and 0≤1-a-b≤0.2; O. The chemical formula of the cobalt oxyhydroxide is xCoOOH·(1-x)Co3O4, wherein 0.85≤x≤1; optionally, 0.94≤x≤1.

5. A method for producing cobalt oxyhydroxide, characterized by, Comprise: a synthesis process: adding a cobalt salt solution, a precipitating agent and an oxidizing agent into a base solution, performing a synthesis reaction, and preparing a post-reaction slurry; a post-treatment process: post-treating the post-reaction slurry to obtain a cobalt oxyhydroxide; wherein, during the reaction of the synthesis process, the feed flow rate ratio of the cobalt salt solution, the precipitating agent and the oxidizing agent is 1:(0.25-0.80):(0.05-0.60).

6. The method for preparing cobalt hydroxyoxide according to claim 5, characterized in that, Satisfy at least one of the following conditions: a. In the synthesis process, the concentration of hydroxide ions in the base solution is 1-6.5 mol / L, and is optionally 1-3 mol / L; b. The post-treatment process specifically comprises: sequentially washing, drying and crushing the post-reaction slurry to obtain a cobalt oxyhydroxide; c. The cobalt salt solution comprises at least one of cobalt chloride, cobalt sulfate or cobalt nitrate. d. the precipitant comprises at least one of potassium hydroxide solution or sodium hydroxide solution; e. the oxidant comprises at least one of hydrogen peroxide, sodium hypochlorite, sodium persulfate or ammonium persulfate.

7. The method for preparing cobalt hydroxyoxide according to claim 5 or 6, characterized in that, The preparation method satisfies at least one of the following conditions: f. the mass concentration of cobalt ions in the cobalt salt solution is 1-3 mol / L; g. the mass fraction of solute in the precipitant is 28-36 wt%; h. the mass fraction of solute in the oxidant is 25-30 wt%; i. the synthesis process is carried out in a reaction container, and the flow rate of the cobalt salt solution is 5-25% of the volume of the reaction container per hour; j. the synthesis process is carried out in a reaction container, and the reaction is ended when the volume of the reaction container is 70-90%; k. the reaction temperature of the synthesis process is 35-70℃; l. the synthesis process is carried out under stirring, and the stirring rate is controlled to be 240-500 r / min; m. in the post-treatment process, when the drying treatment is carried out, the temperature of the drying is 120-140℃, and / or the time of the drying is 15-25 h.

8. A method for producing cobalt oxyhydroxide according to any one of claims 1 to 4, characterized by, The preparation method comprises: a synthesis process: adding a cobalt salt solution, a precipitant and an oxidant into a base solution to carry out a synthesis reaction to obtain a post-reaction slurry; a post-treatment process: post-treating the post-reaction slurry to obtain cobalt oxyhydroxide; During the reaction of the synthesis process, the flow rate ratio of the cobalt salt solution, the precipitant and the oxidant is 1:(0.25-0.80):(0.05-0.60).

9. A positive electrode material, characterized in that, The coating material of the positive electrode material or the raw material of the coating material of the positive electrode material comprises the cobalt oxyhydroxide of any one of claims 1-4 or the cobalt oxyhydroxide prepared by the preparation method of any one of claims 5-7; and the amount of the cobalt oxyhydroxide is 1-5 wt% of the mass of the positive electrode material.

10. A battery, characterized by The battery comprises a positive electrode made of the positive electrode material of claim 9, and the battery is a lithium ion battery or a sodium ion battery.

11. An electrical device, comprising: The electrical equipment comprises the battery of claim 10. The electrical equipment comprises the battery of claim 10.

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