Positive electrode active material, method for manufacturing the same, positive electrode sheet, battery, and electric device

Abstract

The application relates to the technical field of secondary batteries, in particular to a positive electrode active material and a preparation method thereof, a positive electrode sheet, a battery and an electric device. The positive electrode active material comprises lithium iron phosphate, the lithium iron phosphate is secondary particles formed by agglomeration of primary particles, and the particle size number distribution curve of the primary particles presents two characteristic peaks; wherein the highest characteristic peak is a first characteristic peak, and the first characteristic peak peak position R A is 100 nm-250 nm, the first characteristic peak peak position R A corresponding number percentage X A is 44%-54%; the second characteristic peak peak position R B of the primary particles is 270 nm-400 nm, and the second characteristic peak peak position R B corresponding number percentage X B is 2.0%-8.0%. It is shown that the positive electrode active material contains particles with various particle size distributions, which jointly play a role to form step-by-step blending, so that the positive electrode active material has a high compaction density, and a secondary battery containing the same has high capacity and high rate performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary batteries, in particular to a positive electrode active material, a preparation method thereof, a positive electrode sheet, a battery and an electric device. BACKGROUND

[0002] Lithium iron phosphate material has become the most widely used positive electrode material in lithium ion batteries due to its structural stability, good safety and long cycle life. However, with the development of society and technology, people have put forward higher requirements for energy storage devices including lithium ion batteries, so improving the energy density of lithium iron phosphate batteries has become a hot research topic in recent years. Size grading is an effective method to improve the compaction density of powder. At present, it is known that different particle sizes of lithium iron phosphate material are used for dry mixing grading to prepare high-compaction lithium iron phosphate positive electrode material. However, the above scheme adds the preparation of lithium iron phosphate precursors with different particle sizes, and the material needs to be dry mixed, so the uniformity of mixing cannot be guaranteed, and in fact high-performance lithium iron phosphate positive electrode material cannot be obtained. SUMMARY

[0003] The present application aims to at least partly solve one of the problems in the related art. To this end, the present application provides a positive electrode active material, a preparation method thereof, a positive electrode sheet, a battery and an electric device, which can realize a grading structure, has a high-uniform carbon coating layer, has high compaction and relatively optimal electrochemical performance, and the preparation method of the positive electrode active material is simple and suitable for large-scale industrial production.

[0004] To this end, the present application provides a positive electrode active material prepared by step-by-step mixing, comprising lithium iron phosphate, wherein the lithium iron phosphate is secondary particles formed by agglomeration of primary particles, and the particle size number distribution curve of the primary particles presents two characteristic peaks.

[0005] The highest characteristic peak is the first characteristic peak, and the peak position R A of the first characteristic peak is 100nm-250nm, and the peak position R A of the first characteristic peak corresponds to a number percentage X A of 44%-54%.

[0006] The peak position R B of the second characteristic peak of the primary particles is 270nm-400nm, and the peak position R B of the second characteristic peak corresponds to a number percentage X B of 2.0%-8.0%.

[0007] The positive electrode active material provided by this invention is a multi-stage blend, and the particle size distribution curve of the primary particles exhibits two characteristic peaks, corresponding to the presence of particles with various particle size distributions in the positive electrode active material, which work together to form a step-by-step blend. The main peak of the two characteristic peaks is located between 100nm and 250nm, corresponding to a quantity percentage X. A The density is 44%-54%, indicating that the positive electrode active material contains a sufficient number of nano-sized single crystal particles, which can fill the gaps between large particles, thereby achieving ultra-high compaction density. At the same time, nano-sized single crystals can improve the problem of long ion migration paths, enabling secondary batteries containing this positive electrode active material to achieve higher capacity and higher rate performance.

[0008] According to an embodiment of the present invention, in the particle size distribution curve of the primary particles, there is a first minimum value R between the first characteristic peak and the second characteristic peak. AO The first minimum value R AO The corresponding particle size range is 250nm-300nm, and the first minimum value R AO The corresponding quantity percentage X AO It ranges from 1.0% to 5.0%.

[0009] According to an embodiment of the present invention, the peak splitting index λ of the positive electrode active material is 5%-20%;

[0010] Where λ=(X B -X AO ) / X B ×100%;

[0011] X AO R is the first minimum value between the first characteristic peak and the second characteristic peak. AO The corresponding percentage;

[0012] X B The peak position of the second characteristic peak R B The corresponding percentage of quantity.

[0013] According to an embodiment of the present invention, the D of the primary particle 50 The range is 0.1μm-1.0μm.

[0014] According to an embodiment of the present invention, the D of the secondary particles 50 The range is 0.5μm-1.6μm.

[0015] According to an embodiment of the present invention, the compaction density of the positive electrode active material is 2.55 g / cm³. 3 -2.75g / cm 3 .

[0016] According to an embodiment of the present application, the specific surface area of the positive electrode active material is 11 m 2 / g-15 m 2 / g.

[0017] According to an embodiment of the present application, the positive electrode active material comprises a matrix and a carbon coating layer coated on the surface of the matrix.

[0018] The matrix has a composition shown in Formula I:

[0019] Li 1+a Fe b M c (PO4) d Formula I.

[0020] Wherein, -0.1≤a≤0.1, 0≤b≤1, 0≤c≤0.5, 0≤d≤1.

[0021] M is selected from at least one of La, Ce, Cr, Mo, Ca, Hf, Ti, Fe, Zn, Y, Zr, W, Nb, Sm, Sb, Co, Ni, V, Mg, Na, B and Al.

[0022] According to an embodiment of the present application, M is Sb, and at least one of Al, W, Co, V and Ti.

[0023] According to an embodiment of the present application, the content of the carbon coating layer is 0.5wt%-2wt%, preferably 1wt%-1.5wt%, based on the total weight of the positive electrode active material.

[0024] The second aspect of the present application provides a preparation method of the positive electrode active material of the first aspect, and the preparation method comprises:

[0025] A first mixed solution containing a first iron phosphate, a first lithium source, a first carbon source and a first M source is prepared, and a first slurry is obtained by grinding;

[0026] A second mixed solution containing a second iron phosphate, a second lithium source, a second carbon source and a second M source is prepared, and a second slurry is obtained by grinding;

[0027] The first slurry and the second slurry are mixed, and the positive electrode active material is obtained by spray drying and sintering;

[0028] Wherein, the particle size of the first iron phosphate is 80nm-200nm; and the particle size of the second iron phosphate is 60nm-150nm.

[0029] The particle size D 50 of the first slurry is less than the particle size D 50 of the second slurry, and the difference is not less than 0.15μm.

[0030] The present application prepares a first slurry with smaller particle size and a second slurry with larger particle size, the slurry with different particle sizes is mixed, the mixing degree of the slurry particles is good due to the slurry particles in a solution state, the mixing and grading of the particles in the slurry stage are realized, in the subsequent sintering and crystallization process, the particle growth degree grows with the level of the primary particles, the particle grading of the material is greatly optimized, the particles are more closely combined, and the positive electrode active material with high capacity and high tap density performance is prepared. Meanwhile, the preparation method has a simple process flow and low equipment requirement, and is suitable for large-scale industrial production.

[0031] According to the embodiment of the present application, the specific surface area of the first iron phosphate is 7m 2 / g-13m 2 / g.

[0032] According to the embodiment of the present application, the specific surface area of the second iron phosphate is 5m 2 / g-12m 2 / g.

[0033] According to the embodiment of the present application, the first iron phosphate satisfies the iron-phosphorus molar ratio Fe / P of 0.960-0.980.

[0034] According to the embodiment of the present application, the second iron phosphate satisfies the iron-phosphorus molar ratio Fe / P of 0.950-0.970.

[0035] According to the embodiment of the present application, the first lithium source and the second lithium source are independently selected from one of lithium hydroxide, lithium carbonate and lithium acetate.

[0036] According to the embodiment of the present application, the lithium-iron molar ratio Li / Fe of the first lithium source and the first iron phosphate is 1.01-1.07.

[0037] According to the embodiment of the present application, the lithium-iron molar ratio Li / Fe of the second lithium source and the second iron phosphate is 1.01-1.07.

[0038] According to the embodiment of the present application, the first carbon source is selected from at least one of glucose, sucrose, starch, polyethylene glycol and citric acid.

[0039] According to the embodiment of the present application, the addition amount of the first carbon source satisfies that the mass ratio of carbon to the positive electrode active material is 1.0wt%-1.8wt%.

[0040] According to the embodiment of the present application, the second carbon source is selected from at least one of glucose, sucrose, polyethylene glycol and citric acid.

[0041] According to the embodiment of the present application, the addition amount of the second carbon source satisfies that the mass ratio of carbon to the positive electrode active material is 1.0wt%-1.4wt%.

[0042] According to an embodiment of the present application, the solid content of the first slurry is 35wt%-50wt%.

[0043] According to an embodiment of the present application, the solid content of the second slurry is 35wt%-50wt%.

[0044] According to an embodiment of the present application, the D50 of the first slurry is 0.15-0.50μm. 50

[0045] According to an embodiment of the present application, the D50 of the second slurry is 0.35-1.00μm. 50

[0046] According to an embodiment of the present application, the inlet air temperature of the spray drying is 220-280℃, and the outlet air temperature is 100-120℃.

[0047] According to an embodiment of the present application, the first slurry and the second slurry are mixed in a mass ratio of (3:7)-(7:3).

[0048] According to an embodiment of the present application, the sintering temperature is 720-830℃, and the sintering time is 6-12h.

[0049] The third aspect of the present application provides a positive electrode sheet, which comprises the positive electrode active material of the first aspect or the positive electrode active material prepared by the preparation method of the second aspect. Thus, the sheet has high tap density and exhibits high capacity and high rate performance in electrochemical operation.

[0050] The fourth aspect of the present application provides a battery, which comprises the positive electrode sheet of the third aspect. Thus, the battery has good electrochemical performance.

[0051] The fifth aspect of the present application provides an electric device, which comprises the battery of the fourth aspect.

[0052] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0053] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0054] Figure 1 shows the SEM image of the lithium iron phosphate positive electrode active material prepared in Example 1 of the present application;

[0055] Figure 2 ​​The XRD pattern of the lithium iron phosphate positive electrode active material prepared in Example 1 of the present application is shown;

[0056] Figure 3 The particle size number distribution curve of the primary particles of the lithium iron phosphate positive electrode active material prepared in Example 1 of the present application is shown;

[0057] Figure 4 The particle size number distribution curve of the primary particles of the lithium iron phosphate positive electrode active material prepared in Comparative Example 1 of the present application is shown;

[0058] Figure 5 The charge-discharge curve of the coin cell prepared from the lithium iron phosphate positive electrode active material prepared in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0059] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0060] In this text, the mention of "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean that it refers to the same embodiment, nor is it independent or alternative to other embodiments. The skilled person in the art explicitly and implicitly understands that the embodiments described herein can be combined with other embodiments.

[0061] The "range" disclosed in the present application is defined in the form of lower limit and upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way can include or not include the end value, and can be arbitrarily combined, i.e. any lower limit can be combined with any upper limit to form a range. For example, if the ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges of 60-110 and 80-120 are also anticipated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4 and 5 are listed, the following ranges are all anticipated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise stated, the numerical range "a-b" represents a shorthand notation for any real combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, and "0-5" is only a shorthand notation for these numerical combinations. In addition, when a parameter is stated to be ≥2 integers, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0062] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

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

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

[0065] The first aspect of the present invention provides a positive electrode active material, wherein the positive electrode active material is a secondary particle formed by the agglomeration of primary particles, and the particle size distribution curve of the primary particles exhibits two characteristic peaks.

[0066] Among them, the highest characteristic peak is the first characteristic peak, and the peak position of the first characteristic peak is R. A The wavelength range is 100nm-250nm, and the peak position of the first characteristic peak is R. A The corresponding quantity percentage X A It ranges from 44% to 54%;

[0067] The peak position R of the second characteristic peak of the primary particle B The wavelength is 270nm-400nm, and the peak position of the second characteristic peak is R. B The corresponding quantity percentage X B It ranges from 2.0% to 8.0%.

[0068] The particle size distribution curve of the primary particles in the positive electrode active material provided by this invention exhibits two characteristic peaks, indicating that the positive electrode active material contains primary particles of at least two particle sizes. The main peak is located between 100nm and 250nm, corresponding to a percentage X. Ais 44%-54%, indicating that the positive active material contains a sufficient number of nanoscale single crystal particles which can fill in the gaps of large particles to significantly improve the overall powder compaction density. At the same time, the grading of particles of different sizes can increase the solid volume fraction and the packing density in the battery, improve the active material load per unit volume of the slurry layer, i.e. improve the filling density, so as to achieve the purpose of improving the battery capacity and energy density. The voids and pores of the active particles are the diffusion channels of lithium ions, and the size grading of particles makes the active particles have more surface in contact with the electrolyte, increases the utilization rate of active material, is beneficial to the charge transfer at the electrode / electrolyte interface, and can improve the specific capacity of the battery.

[0069] The particle size number distribution curve is plotted with the particle size of primary particles as the abscissa and the percentage of the sum of the number of particles having the particle size in the total sum of the number of particles as the ordinate.

[0070] According to a specific embodiment of the present application, the second characteristic peak of the primary particles has a peak position R B is 270nm-400nm, the second characteristic peak has a peak position R B corresponding to the percentage X B is 2.0%-8.0%. Thus, the primary particles have small particles in this particle size range, which can further effectively fill the voids of large particles, so that the positive active material obtains high compaction density. When the particle size is too large, it will lead to too long ion migration path, reducing the capacity and charge-discharge efficiency; when the particle size is too small, it will affect the cycle life of the material, so when the second characteristic peak is in the range of 270nm-400nm, the capacity and cycle balance of the particles themselves can be considered. At the same time, the second characteristic peak has a peak position R B corresponding to the percentage X B is 2.0%-8.0%, further ensuring the high compaction density, cycle balance and rate performance of the material, etc.

[0071] According to a specific embodiment of the present application, the first characteristic peak and the second characteristic peak have a first minimum value R AO , the first minimum value R AO corresponds to a particle size range of 250nm-300nm, and the first minimum value R AO corresponds to the percentage X AO is 1.0%-5.0%. Thus, the first characteristic peak and the second characteristic peak have a relatively obvious peak separation effect.

[0072] According to a specific embodiment of the present application, the peak separation index λ of the positive active material is 5%-20%;

[0073] wherein λ=(X B -X AO ) / X B ×100%.

[0074] X AO is a first minimum value R between the first characteristic peak and the second characteristic peak AO corresponding number percentage;

[0075] X B is a peak position R of the second characteristic peak B corresponding number percentage.

[0076] When the particle size distribution of the second characteristic peak is too wide, and small particles are mixed, then the peak separation index λ of the positive electrode active material is smaller, and the depth of lithium deintercalation during the charging and discharging process is obviously different, resulting in a large capacity difference, and the intrinsic charge transfer impedance results in too large impedance and rate difference, reducing the overall capacity and rate performance of the material. Therefore, when the peak separation index λ meets the limitation of the present application, on the one hand, the small and large particles can be effectively distributed in the structure to form a filling effect, so that the positive electrode active material obtains a higher compaction density; on the other hand, the mixing of too large particles is avoided, so that the large particles can maintain good capacity and cycle performance.

[0077] According to a specific embodiment of the present application, the D 50 of the primary particles is 0.1 μm-1.0 μm. As some specific examples, the D 50 of the primary particles is 0.1 μm, 0.5 μm, 1.0 μm, etc.

[0078] According to a specific embodiment of the present application, the D 50 of the secondary particles is 0.5 μm-1.6 μm. As some specific examples, the D 50 of the secondary particles is 0.5 μm, 1 μm, 1.5 μm, 1.6 μm, etc.

[0079] According to a specific embodiment of the present application, the compaction density of the positive electrode active material is 2.55 g / cm 3 -2.75 g / cm 3 . As some specific examples, the compaction density of the positive electrode active material is 2.55 g / cm 3 , 2.65 g / cm 3 , 2.75 g / cm 3 , etc.

[0080] According to a specific embodiment of the present application, the specific surface area of the positive electrode active material is 11 m 2 / g-15 m 2 / g. As some specific examples, the specific surface area of the positive electrode active material is 11 m 2 / g, 12 m 2 / g, 13 m 2 / g, 14 m2 / g, 15 m 2 / g, etc.

[0081] According to a specific embodiment of the present application, the positive electrode active material comprises a substrate and a carbon coating layer coated on the surface of the substrate;

[0082] wherein the substrate has a composition shown in Formula I:

[0083] Li 1+a Fe b M c (PO4) d Formula I;

[0084] wherein -0.1≤a≤0.1, 0≤b≤1, 0≤c≤0.5, 0≤d≤1;

[0085] M is selected from at least one of La, Ce, Cr, Mo, Ca, Hf, Ti, Fe, Zn, Y, Zr, W, Nb, Sm, Sb, Co, Ni, V, Mg, Na, B and Al;

[0086] Preferably, M is Sb, and at least one of Al, W, Co, V and Ti. That is, M must contain Sb, and further contains at least one of Al, W, Co, V and Ti.

[0087] According to a specific embodiment of the present application, the content of the carbon coating layer is 0.5wt%-2wt% based on the total weight of the positive electrode active material, and as some specific examples, the content of the carbon coating layer is 0.5wt%, 1wt%, 1.5wt%, 2wt% and the like, and preferably 1wt%-1.5wt%.

[0088] The second aspect of the present application provides a preparation method of the above positive electrode active material, and the preparation method comprises:

[0089] (1) preparing a first mixed solution containing a first iron phosphate, a first lithium source, a first carbon source and a first M source, and grinding to obtain a first slurry.

[0090] According to a specific embodiment of the present application, the particle size of the first iron phosphate is 80nm-200nm, and as some specific examples, the particle size of the first iron phosphate can be 80nm, 100nm, 150nm, 200nm and the like.

[0091] According to a specific embodiment of the present application, the specific surface area of the first iron phosphate is 7m 2 / g-13m 2 / g, and as some specific examples, the specific surface area of the first iron phosphate can be 7m 2 / g, 8m 2 / g, 9m2 / g, 10m 2 / g, 11m 2 / g, 12m 2 / g, 13m 2 / g, etc. Further, the first iron phosphate satisfies the iron-phosphorus molar ratio Fe / P of 0.960-0.980, such as 0.960, 0.970, 0.980, etc.

[0092] According to a specific embodiment of the present application, the specific type of the first lithium source is not particularly limited, and a person skilled in the art can select according to the actual situation, for example, the first lithium source can include at least one of lithium hydroxide, lithium carbonate, lithium acetate, preferably lithium carbonate, more preferably the purity of lithium carbonate is ≥99.5%.

[0093] According to a specific embodiment of the present application, the lithium-iron molar ratio Li / Fe of the first lithium source and the first iron phosphate is 1.01-1.07, such as 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, etc.

[0094] According to a specific embodiment of the present application, the specific type of the first carbon source is not particularly limited, and a person skilled in the art can select according to the actual situation, for example, the first carbon source can include at least one of glucose, sucrose, starch, polyethylene glycol, citric acid. Further, the addition amount of the first carbon source satisfies the mass ratio of carbon mass to the mass of the positive active material of 1.0wt%-1.8wt%, such as 1.0wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, etc.

[0095] According to a specific embodiment of the present application, the specific type of the first M source is not particularly limited, and a person skilled in the art can select according to the actual situation, for example, the first M source can include at least one of a salt, a hydroxide, an oxide capable of providing at least one element of La, Ce, Cr, Mo, Ca, Hf, Ti, Fe, Zn, Y, Zr, W, Nb, Sm, Sb, Co, Ni, V, Mg, Na, B and Al, preferably titanium dioxide, ammonium metavanadate, tungsten trioxide, magnesium oxide, cobalt hydroxide oxide, niobium pentoxide, antimony trioxide, aluminum trioxide, wherein the addition amount of titanium dioxide, ammonium metavanadate, tungsten trioxide, antimony trioxide satisfies the titanium, vanadium, tungsten, antimony content of the target positive active material is respectively 1000ppm-5000ppm, 1000ppm-2000ppm, 500ppm-2000ppm, 500-2000ppm.

[0096] According to specific embodiments of the present application, the first mixed solution is prepared in a manner not particularly limited, which does not affect subsequent steps such as grinding, spray drying, etc. Specifically, the first mixed solution can be obtained by dissolving the first iron phosphate, the first lithium source, the first carbon source, and the first M source in a solvent, which includes but is not limited to deionized water.

[0097] According to specific embodiments of the present application, the solid content of the first slurry is 35wt%-50wt%, and the grinding causes the particle size D 50 of the first slurry to be 0.15μm-0.50μm. Wherein, the grinding manner is not particularly limited, which can be selected according to the situation in the art, and the particle size of the slurry is realized in the target range, which can be realized by, for example, sanding, etc.

[0098] (2) preparing a second mixed solution containing a second iron phosphate, a second lithium source, a second carbon source, and a second M source, and obtaining a second slurry by grinding.

[0099] According to specific embodiments of the present application, the particle size of the second iron phosphate is 60nm-150nm, and as some specific examples, the particle size of the second iron phosphate can be 60nm, 80nm, 100nm, 120nm, 140nm, 150nm, etc.

[0100] According to specific embodiments of the present application, the specific surface area of the second iron phosphate is 5m 2 / g-12m 2 / g, and as some specific examples, the specific surface area of the second iron phosphate can be 5m 2 / g, 6m 2 / g, 7m 2 / g, 8m 2 / g, 9m 2 / g, 10m 2 / g, 11m 2 / g, 12m 2 / g, etc. Further, the second iron phosphate satisfies the iron-phosphorus molar ratio Fe / P of 0.950-0.970, for example, 0.950, 0.960, 0.970, etc.

[0101] According to specific embodiments of the present application, the specific type of the second lithium source is not particularly limited, which can be selected according to the actual situation by those skilled in the art, for example, the second lithium source can include at least one of lithium hydroxide, lithium carbonate, lithium acetate, preferably lithium carbonate, and more preferably the purity of lithium carbonate is ≥99.5%.

[0102] According to a specific embodiment of the present application, the lithium-iron molar ratio Li / Fe of the second lithium source and the second iron phosphate is 1.01-1.07, such as 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, etc.

[0103] According to a specific embodiment of the present application, the specific type of the second carbon source is not particularly limited, and can be selected by those skilled in the art according to actual conditions. For example, the second carbon source can include at least one of glucose, sucrose, polyethylene glycol, and citric acid. Further, the addition amount of the second carbon source satisfies that the mass ratio of carbon to the positive active material is 1.0wt%-1.4wt%, such as 1.0wt%, 1.2wt%, 1.4wt%, etc.

[0104] According to a specific embodiment of the present application, the specific type of the second M source is not particularly limited, and can be selected by those skilled in the art according to actual conditions. For example, the second M source can include at least one of a salt, a hydroxide, and an oxide capable of providing at least one element selected from the group consisting of La, Ce, Cr, Mo, Ca, Hf, Ti, Fe, Zn, Y, Zr, W, Nb, Sm, Sb, Co, Ni, V, Mg, Na, B, and Al, preferably, aluminum oxide, titanium dioxide, ammonium metavanadate, tungsten trioxide, magnesium oxide, cobalt oxyhydroxide, niobium pentoxide, antimony trioxide, wherein the addition amount of titanium dioxide, ammonium metavanadate, tungsten trioxide, and antimony trioxide satisfies that the titanium, vanadium, tungsten, and antimony content of the target positive active material is 1000ppm-5000ppm, 1000ppm-2000ppm, 500ppm-2000ppm, 500ppm-2000ppm, respectively.

[0105] According to a specific embodiment of the present application, the preparation method of the second mixed solution is not particularly limited, and does not affect the subsequent steps such as grinding and spray drying. Specifically, the second mixed solution can be obtained by dissolving the second iron phosphate, the second lithium source, the second carbon source, and the second M source in a solvent, which includes but is not limited to deionized water.

[0106] According to a specific embodiment of the present application, the solid content of the second slurry is 35wt%-50wt%, and the grinding makes the particle size D 50 of the second slurry be 0.35μm-1.00μm. Wherein, the grinding method is not particularly limited, and can be selected by those skilled in the art according to actual conditions, as long as the particle size of the slurry is within the target range, which can be achieved by, for example, sanding.

[0107] According to a specific embodiment of the present application, the particle size D 50 of the first slurry is less than the particle size D 50, and the difference is not less than 0.15 mu m, thereby obtaining the first slurry with smaller particle size and the second slurry with larger particle size, the slurry particles are mixed uniformly due to being in a solution state, the mixing gradation of the particles of different sizes is realized, in the subsequent sintering and crystallization process, the particle growth degree is increased along with the horizontal growth of the primary particles, the particle gradation of the material is greatly optimized, the combination between the particles is more compact, and the positive electrode active material with high capacity and high tap density performance is prepared.

[0108] (3) mixing the first slurry and the second slurry, and obtaining the positive electrode active material through spray drying and sintering.

[0109] According to a specific embodiment of the present application, the mixing ratio of the first slurry and the second slurry is not particularly limited, and can be reasonably adjusted by those skilled in the art according to the situation. As some specific examples, the first slurry and the second slurry are mixed in a mass ratio of (3:7)-(7:3), for example, 3:7, 2:3, 1:1, 3:2, 7:3, etc.

[0110] According to a specific embodiment of the present application, the inlet air temperature and the outlet air temperature of the spray drying are not particularly limited, that is, the drying of the slurry is realized, preferably, the water content of the product after spray drying is ≤3.0%. As some specific examples, the inlet air temperature of the spray drying can be 220-280 DEG C, and the outlet air temperature is 100-120 DEG C.

[0111] According to a specific embodiment of the present application, the sintering temperature and time are not particularly limited, and can be reasonably adjusted by those skilled in the art according to the situation. As some specific examples, the sintering temperature can be 720-830 DEG C, and the sintering time is 6-12 h. Further, the sintering is preferably carried out in an inert atmosphere, for example, nitrogen, etc.

[0112] The third aspect of the present application provides a positive electrode tab, which comprises the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect.

[0113] The positive electrode tab generally comprises a positive electrode current collector and a positive electrode active material layer arranged on the positive electrode current collector, and the positive electrode active material layer comprises the positive electrode active material.

[0114] The positive electrode current collector can adopt a conventional metal foil or a composite current collector (a metal material can be arranged on a polymer substrate to form a composite current collector). As an example, the positive electrode current collector can comprise at least one of a copper foil, an aluminum foil, a nickel foil, a stainless steel foil, a stainless steel mesh, and a carbon-coated aluminum foil.

[0115] The positive electrode active material comprises the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect.

[0116] The positive electrode active material layer can further optionally include a conductive agent for improving the conductivity of the positive electrode active material layer and a binder for firmly binding the positive electrode active material and the binder to the positive electrode current collector. The present application does not specifically limit the types of the conductive agent and the binder, and they can be selected according to actual needs.

[0117] As an example, the conductive agent can include at least one of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and the binder can include at least one of polyvinylidene fluoride (PVDF), a vinylidene fluoride copolymer, or a modified (e.g., carboxylic acid, acrylic acid, acrylonitrile, etc.) derivative thereof.

[0118] These materials can all be obtained through commercial channels.

[0119] The fourth aspect of the present application provides a battery including the positive electrode tab according to the third aspect of the present application. Thus, the battery has excellent cycle life.

[0120] The battery refers to a battery that can be continuously used by activating the active material through charging after discharging.

[0121] It can be understood that the battery according to the present application is a lithium ion battery.

[0122] Generally, the battery includes a positive electrode tab, a negative electrode tab, a separator, and an electrolyte. During the charging and discharging of the battery, active ions are inserted and extracted between the positive electrode tab and the negative electrode tab. The separator is disposed between the positive electrode tab and the negative electrode tab and serves to isolate them. The electrolyte serves to conduct ions between the positive electrode tab and the negative electrode tab.

[0123] [Negative electrode tab]

[0124] In the battery, the negative electrode tab can be lithium metal or a lithium-containing alloy.

[0125] In some embodiments, in order to further improve the energy density of the battery, the negative electrode active material can include a silicon-based material.

[0126] The negative electrode active material layer can also optionally include a binder, a conductive agent, and other optional additives.

[0127] As an example, the conductive agent can include one or more of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0128] As an example, the binder can include one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0129] As an example, the other optional additives can include thickening and dispersing agents (e.g., sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials.

[0130] [Electrolyte]

[0131] The electrolyte can include an electrolyte salt and a solvent.

[0132] As an example, the electrolyte salt can include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate borate (LiDFOB), lithium difluorophosphate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorophosphate dioxalate (LiDFOP), and lithium tetrafluorophosphate oxalate (LiTFOP).

[0133] As an example, the solvent can include at least one of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0134] In some embodiments, an additive can also be included in the electrolyte. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive capable of improving certain properties of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature performance of the battery, and an additive for improving low-temperature performance of the battery.

[0135] [Separator]

[0136] As the separator film described above, the present application is not particularly limited, and any known porous structure separator film having electrochemical stability and mechanical stability can be used according to the actual needs, for example, can include a combination of at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester and natural fiber.

[0137] The fifth aspect of the present application provides a power utilization device comprising the battery of the fourth aspect. Specifically, the battery can serve as a power source of the power utilization device, or as an energy storage unit of the power utilization device. The power utilization device can include, but is not limited to, a mobile device (such as a mobile phone, a notebook computer), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck), an electric train, a ship and a satellite, an energy storage system.

[0138] The solutions of the present application will be explained below in connection with the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. If the specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or according to the product instructions are used. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be obtained commercially.

[0139] The relevant parameters in the following examples and comparative examples are tested by the following methods:

[0140] (1) Morphology test: tested by a scanning electron microscope of Regulus8100 model of Japan Hitachi Company;

[0141] (2) X-ray diffraction (XRD) test: tested by a SmartLab 9kW X-ray diffractometer of Japan Rigaku Company;

[0142] (3) Median particle size D 50 : tested by a laser particle size analyzer of Mastersizer 3000 model of Marven Company;

[0143] (4) Average primary particle size: the scanning electron microscope image of the prepared lithium iron phosphate positive electrode active material is taken at 30.0K times, and the average primary particle size is counted by using LIBMAS and Nano Measurer software;

[0144] (5) Specific surface area (BET) test: tested by a specific surface area instrument of Tristar 3020 model of Micromeritics Company;

[0145] (6) Powder compaction density test: 1 g of the prepared lithium iron phosphate positive electrode active material was weighed into a compaction mold, the mold was placed into a compaction device to test the results under a 30 KN pressure;

[0146] (7) Particle size number distribution test: a scanning electron microscope image of the prepared lithium iron phosphate positive electrode active material was taken at 30.0 K times, and data was obtained by using LIBMAS analysis software for statistics;

[0147] (8) Particle size volume distribution test: obtained by a laser particle size analyzer of a model of Mastersizer 3000 of Marvern Company;

[0148] (9) Electrochemical performance test: a half-cell was used for the test, the test voltage was 2.5 V-4.2 V, charging was performed to 4.2 V in a constant current and constant voltage manner, discharging was performed to 2.5 V in a constant current manner, the charge and discharge current was 0.1 C for 2 cycles; then the charge and discharge current was 0.2 C for 1 cycle; then the charge and discharge current was 0.33 C for 1 cycle; then the charge and discharge current was 0.5 C for 1 cycle; then the charge and discharge current was 1 C for 1 cycle; then the charge and discharge current was 2 C for 1 cycle, and the cutoff voltage condition was the same as 0.1 C.

[0149] Example 1

[0150] Preparation of lithium iron phosphate positive electrode active material

[0151] (1) 5004.0 g of iron phosphate with a Fe / P molar ratio of 0.970, a specific surface area of 10.0 m 2 / g, and a primary particle size of 90 nm was mixed with 1235.10 g of lithium carbonate, 420 g of glucose, 150 g of polyethylene glycol, titanium dioxide, ammonium metavanadate, tungsten trioxide, antimony trioxide, and 11250 g of pure water were added to a stirring mill to form a first mixed solution; the first mixed solution was pumped into a sand mill for sand milling below 45°C, the sand milling particle size D 50 was controlled to be 0.25 μm, and the solid content was 38 wt%, to obtain a first slurry;

[0152] (2) 4008.0 g of iron phosphate with a Fe / P molar ratio of 0.960, a specific surface area of 8.0 m 2 / g, and a primary particle size of 150 nm was mixed with 984.0 g of lithium carbonate, 305 g of glucose, 120 g of polyethylene glycol, 8.20 g of titanium dioxide, and 8830 g of pure water were added to a stirring mill to form a second mixed solution; the second mixed solution was pumped into a sand mill for sand milling below 45°C, the sand milling particle size D 50 was controlled to be 0.65 μm, and the solid content was 38 wt%, to obtain a second slurry;

[0153] (3) The first slurry and the second slurry were stirred uniformly in a stirring tank at a mass ratio of 7:3 to obtain a third slurry; the third slurry was spray dried, the feeding port temperature was controlled at 260°C, and the discharging port temperature was controlled at 110°C to prepare a spray feed precursor; the spray feed precursor powder was calcined at a high temperature under a nitrogen atmosphere, the sintering temperature was controlled at 800°C, and the sintering time was 12 h; and then the powder was crushed, the particle size D 50 was controlled at 1.4 μm, and the average primary particle size was 160 nm to prepare a high-capacity, high-tap-density lithium iron phosphate positive electrode material.

[0154]

Preparation of the positive electrode sheet

[0155] The lithium iron phosphate positive electrode active material prepared above, 50% Compressed Denka Black (acetylene black, compression ratio 50%), and polyvinylidene fluoride (PVDF) were dispersed in N-methyl pyrrolidone (NMP) at a mass ratio of 96.5:1.5:2, and then uniformly ball-milled and dispersed, coated on an aluminum foil, vacuum dried to prepare a positive electrode sheet.

[0156]

Preparation of the negative electrode sheet

[0157] The negative electrode used a Li metal sheet.

[0158]

Preparation of the electrolyte

[0159] A 1.1 mol / L LiPF6 solution was used as the electrolyte, and an equal-volume mixture of ethylene carbonate (EC), methyl ethyl carbonate (EMC), and dimethyl carbonate (DMC) was used as the solvent.

[0160]

Separator film

[0161] A Celgard polypropylene film was used as the separator film.

[0162] The positive electrode sheet, the separator film, the negative electrode sheet, and the electrolyte were assembled into a coin cell half-battery.

[0163] The lithium ion batteries containing the positive electrode active material of Examples 2-6 and Comparative Examples 2-3 were the same as Example 1 except for some parameters (see Table 1).

[0164] The scheme of Comparative Example 1 was specifically as follows:

[0165] (1) 2784.0 g of iron phosphate with a Fe / P molar ratio of 0.970, a specific surface area of 10.0 m 2 / g, and a primary particle size of 90 nm, and 1197.0 g of iron phosphate with a Fe / P molar ratio of 0.960, a specific surface area of 8.0 m 2and 984.30 g of lithium carbonate are mixed, 310 g of glucose and 120 g of polyethylene glycol are added, and 16.80 g of titanium dioxide, 13.50 g of ammonium metavanadate and 8890 g of pure water are added into the stirring mill to form a first mixed solution; the first mixed solution is poured into a sand mill and sand milled below 45°C, and the sand milled particle size D 50 is controlled to be 0.45 pm, and the solid content is 38 wt%, to obtain a first slurry;

[0166] The first slurry is spray dried, the temperature of the feeding port is controlled to be 245°C, and the temperature of the discharging port is controlled to be 95°C, to obtain a first precursor with a particle size D50 of 25 pm and a moisture content of ≤3.0%;

[0167] (2) The first precursor powder is calcined at a high temperature under a nitrogen atmosphere, the sintering temperature is controlled to be 800°C, and the sintering time is 12 h; then the first precursor powder is crushed, and the particle size D 50 is controlled to be 1.5 pm, and the average value of the primary particle size is 180 nm, to obtain a lithium iron phosphate positive electrode material.

[0168] The primary particle size distribution data of the positive electrode active materials obtained in Examples 1-6 and Comparative Examples 1-3 are shown in Table 2, and the performance parameters of the positive electrode active materials are shown in Table 3.

[0169] Among them, Example 2 is different from Example 1 in that the mixing ratio of the first slurry and the second slurry is adjusted; Example 3 is different from Example 1 in that the D 50 size of the first slurry and the second slurry and the mixing ratio of the slurries are adjusted; Example 4 is different from Example 1 in that the selection of the M source is adjusted, Sb is removed, and the Ti content is increased; Example 5 is different from Example 1 in that the particle size of the first iron phosphate, the D 50 size of the first slurry and the second slurry are adjusted; and Example 6 is different from Example 1 in that the particle size of the first iron phosphate, the particle size of the second iron phosphate, the D 50 size of the first slurry and the second slurry are adjusted; and the amounts of titanium dioxide, ammonium metavanadate, tungsten trioxide and antimony trioxide added in step (1) are adjusted so that the chemical formula is as shown in Table 3.

[0170] Comparative Example 1 is different from Example 1 in that the first slurry and the second slurry are not prepared separately, but the mixed solution containing the first iron phosphate and the mixed solution containing the second iron phosphate are mixed at the same time, and then the grinding, drying and calcination processes are performed, and the raw materials do not contain tungsten trioxide and antimony trioxide; Comparative Example 2 is different from Example 1 in that the D 50 size of the first slurry and the mixing ratio of the two slurries are adjusted; and Comparative Example 3 is different from Example 1 in that the D 50 size of the second slurry is adjusted.

[0171] Table 1

[0172]

[0173] In Table 1, " / " represents no addition or none.

[0174] Table 2

[0175]

[0176] In Table 1, " / " represents none.

[0177] Table 3

[0178]

[0179] Result analysis:

[0180] Compared with Comparative Examples 1-3, the positive electrode active material prepared by the method provided in the present application (i.e. Examples 1-6) has higher compaction density and better rate performance and higher capacity.

[0181] wherein, Figure 1 The SEM image of the lithium iron phosphate positive electrode active material prepared in Example 1 can be seen to have mixed particles of various different particle sizes. Figure 2 The XRD image of the material can be seen to have a lithium iron phosphate structure. Figure 3 The particle size number distribution curve of the primary particles of the material can be seen to have two obvious characteristic peaks. Figure 5 The charge-discharge cycle test results of the material, combined with Figure 1 and Figure 3 can be seen that the material prepared in Example 1 is in a multi-stage mixed form, so that the material has a higher compaction density and better electrochemical performance.

[0182] Similarly, the remaining examples have the same excellent effects. Among them, Example 4, compared with Example 1, changes the selection of the M element, removes Sb, and the results show that it does not affect the compaction density of the positive electrode active material, but reduces the capacity of the battery containing the positive electrode active material, but is still higher than Comparative Examples 1-3, indicating that the selection of the M source is preferably the Sb source.

[0183] Comparative Example 1 and Example 1 differ in that the two materials with different primary particle sizes are directly mixed, then ground, dried and calcined, so that the preparation method does not realize the size grading of the mixed particles in the slurry stage, and the mixing uniformity is poor, and the disadvantage is further amplified in the subsequent calcination process, combined with Figure 4It can be seen that the particle size number distribution curve of the primary particles of the material has only one obvious characteristic peak, which also proves that the material has not achieved multi-level blending, thus resulting in a decrease in the tap density of the prepared positive electrode active material and a decrease in the capacity of the battery containing the same.

[0184] Comparative Example 2 and Example 1 differ in that the D 50 of the first slurry is different from the D 50 of the second slurry, and the mass ratio of the mixture of the slurries is different. In the comparative example, the D 50 of the first slurry is closer to the D 50 of the second slurry (the difference is 0.05 μm, which is not within the range defined in the present application), and the proportion of the second slurry is high, which cannot achieve a good gradation effect, and thus cannot take into account both high capacity and high tap density performance.

[0185] Similarly, Comparative Example 3 and Example 1 differ in that the D 50 of the second slurry is different. In the comparative example, the D 50 of the first slurry is 0.1 μm different from the D 50 of the second slurry, which is not within the range defined in the present application, and cannot achieve a good gradation effect, and thus cannot take into account both high capacity and high tap density performance.

[0186] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0187] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A positive electrode active material, characterized by, The lithium iron phosphate includes secondary particles formed by agglomeration of primary particles, and a particle size number distribution curve of the primary particles has two characteristic peaks. Wherein, the highest characteristic peak is the first characteristic peak, and the first characteristic peak peak position R A is 100 nm-250 nm, and the first characteristic peak peak position R A corresponds to the quantity percentage X A is 44%-54%. the second characteristic peak position R of the primary particles B is 270 nm - 400 nm, the second characteristic peak position R B corresponds to the percentage amount X B is 2.0% - 8.0%; The first characteristic peak and the second characteristic peak have a first minimum value R AO , the first minimum value R AO corresponds to a particle size range of 250nm-300nm, and the corresponding number percentage X AO at the first minimum value R AO is 1.0%-5.0%; the particle size number distribution curve is a scanning electron microscope image of the prepared lithium iron phosphate positive electrode active material taken at a magnification of 30.0K, and the data is obtained by using LIBMAS analysis software for statistics; The positive electrode active material includes a substrate and a carbon coating layer coated on a surface of the substrate. The substrate has a composition shown in Formula I: Li 1+a Fe b M c (PO4) d Formula I; wherein -0.1≤ a ≤0.1, 0 b ≤1, 0 c ≤0.5, 0 d ≤1; M includes Sb, and M further includes at least one of Al, W, Co, V and Ti.

2. The positive electrode active material according to claim 1, characterized by In the particle size number distribution curve of the primary particles, The peak separation index λ of the positive electrode active material is 5%-20%. where λ = (X B - X AO ) / X B x 100%. X AO the first minimum R between the first and second characteristic peaks AO corresponding percentage number; X B R B the second characteristic peak.

3. The positive electrode active material according to claim 1 or 2, characterized by D90of the primary particles is 0.1-1.0 μm 50 0.1 μm-1.0 μm; Optionally, the D50 of the secondary particles is between 0.5 and 1.6 pm. 50 0.5 pm - 1.6 pm; Optionally, the positive active material has a compaction density of 2.55 g / cm3 3 - 2.75 g / cm3 3 ; Optionally, the specific surface area of the positive electrode active material is 11 m 2 / g-15 m 2 / g.

4. A method for producing the positive electrode active material according to any one of claims 1 to 3, characterized by, The preparation method includes: A first mixed solution containing first lithium phosphate, a first lithium source, a first carbon source and a first M source is prepared, and a first slurry is obtained by grinding; A second mixed solution containing second lithium phosphate, a second lithium source, a second carbon source and a second M source is prepared, and a second slurry is obtained by grinding; The first slurry and the second slurry are mixed, and the positive electrode active material is obtained by spray drying and sintering; The particle size of the first lithium phosphate is 80nm-200nm; and the particle size of the second lithium phosphate is 60nm-150nm. said first slurry particle size D 50 less than the particle size D of said second slurry 50 and the difference is not less than 0.15 pm.

5. The preparation method according to claim 4, characterized in that, The specific surface area of the first iron phosphate is 7 m 2 / g-13 m 2 / g; Optionally, the specific surface area of the second iron phosphate is 5 m 2 / g-12 m 2 / g.

6. The preparation method according to claim 4, characterized in that, D50 of the first slurry is 0.15-0.50 μm 50 0.15 μm-0.50 μm; Optionally, the second slurry has a D 50 0.35 μm - 1.00 μm.

7. The preparation method according to claim 4, characterized in that, The inlet air temperature of the spray drying is 220℃-280℃, and the outlet air temperature is 100℃-120℃; Optionally, the first slurry and the second slurry are mixed in a mass ratio of (3:7)-(7:3); Optionally, the sintering temperature is 720℃-830℃, and the sintering time is 6h-12h.

8. A positive electrode sheet characterized by comprising: The positive electrode sheet includes the positive electrode active material of any one of claims 1-3 or the positive electrode active material prepared by the preparation method of any one of claims 4-7.

9. A battery, characterized by The battery includes the positive electrode sheet of claim 8.

10. An electric device, characterized by The battery includes the battery of claim 9.

Images