Positive electrode active material and preparation method thereof, positive plate and battery

Abstract

The invention discloses a positive electrode active material and a preparation method thereof, a positive plate and a battery. The positive electrode active material is a modified ternary nickel-cobalt-manganese material formed by doping indium oxide and ketjen black into a ternary nickel-cobalt-manganese material; the modified ternary nickel-cobalt-manganese material is a core-shell granular material, the core is a ternary nickel-cobalt-manganese material, and the shell comprises an inner shell and an outer shell; wherein the inner shell is a ketjen black coating layer, and the outer shell is an indium oxide modified layer. Compared with a conventional ternary nickel-cobalt-manganese material, the modified ternary nickel-cobalt-manganese core-shell particle material can remarkably improve the cycle performance of a lithium battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a positive electrode active material and a preparation method thereof, a positive electrode sheet and a battery. Background Art

[0002] Ternary nickel-cobalt-manganese material (NCM material) is a new type of lithium-ion battery positive electrode material composed of three elements: nickel, cobalt and manganese. Ternary nickel-cobalt-manganese material battery has the characteristics of high performance, high energy density and long life, and is widely used in lithium-ion batteries in electric vehicles, mobile phones, laptops and other equipment.

[0003] At present, in the field of power batteries, ternary nickel-cobalt-manganese materials are widely used as positive electrode materials for lithium batteries due to their high capacity and excellent conductivity. The main components are nickel, cobalt and manganese, and the ratio of these three elements can be adjusted within a certain range to meet different battery performance requirements. With the rapid development of new energy, the nickel content in ternary materials has gradually increased, which has also caused some defects.

[0004] High nickel ternary nickel-cobalt-manganese materials are easily exposed to H in the air. 2 O and CO 2 Reaction, generating LiOH and Li on the surface of the material 2 CO 3 , where LiOH reacts with LiPF in the electrolyte 6 The reaction generates HF, while Li 2 CO 3 The presence of oxygen atoms in the NCM material and the reaction of the electrolyte will generate CO 2 , reducing the battery cycle performance. Therefore, how to reduce the residual alkali content on the surface of high-nickel ternary nickel-cobalt-manganese materials to improve the cycle performance has become a top priority. Summary of the invention

[0005] The object of the present invention is to provide a positive electrode active material and a preparation method thereof, a positive electrode sheet and a battery.

[0006] To achieve the above purpose, the technical solution provided by the present invention is:

[0007] The first aspect of the present application provides a positive electrode active material, which is a modified ternary nickel-cobalt-manganese material formed by adding indium oxide and Ketjen black to a ternary nickel-cobalt-manganese material.

[0008] To optimize the above technical solutions, the specific measures taken also include:

[0009] The modified ternary nickel-cobalt-manganese material is a core-shell particle material, the core is a ternary nickel-cobalt-manganese material, and the shell comprises a two-layer structure of an inner shell and an outer shell; wherein the inner shell is a Ketjen black coating layer and the outer shell is an indium oxide modified layer.

[0010] Furthermore, the particle size D50 of the modified ternary nickel-cobalt-manganese material is in the range of 8-12 μm; the thickness of the Ketjen black coating layer is in the range of 1.0-3.8 μm, and the thickness of the indium oxide modified layer is in the range of 0.3-1.5 μm.

[0011] Furthermore, the ternary nickel-cobalt-manganese material is an 8-series high-nickel ternary positive electrode material.

[0012] The second aspect of the present application provides a method for preparing a positive electrode active material, comprising the following steps:

[0013] During the low-temperature calcination process at 300-400° C., the Ketjen black powder is coated with the ternary nickel-cobalt-manganese material to form a primary particle material containing a ternary nickel-cobalt-manganese material core and a Ketjen black coating layer inner shell;

[0014] Then, during a high-temperature calcination process at 500-650° C., the surface of the primary particle material is modified by indium oxide powder to form a modified ternary nickel-cobalt-manganese core-shell particle material containing a ternary nickel-cobalt-manganese material core, a Ketjen black coating layer inner shell and an indium oxide modified layer outer shell.

[0015] To optimize the above technical solutions, the specific measures taken also include:

[0016] The Ketjen black powder and the indium oxide powder are added in sequence, and after the Ketjen black powder is added to the ternary nickel-cobalt-manganese material, the temperature is raised to 300-400°C to form a Ketjen black coating layer, and then the indium oxide powder is added and the temperature is raised to 500-650°C to prepare an indium oxide modified layer; or the Ketjen black powder and the indium oxide powder are added to the ternary nickel-cobalt-manganese material at the same time, and a programmed heating process of 300-400°C in the first stage and 500-650°C in the second stage is carried out to finally obtain a modified ternary nickel-cobalt-manganese core-shell particle material.

[0017] Furthermore, the mass ratio of the ternary nickel-cobalt-manganese material to Ketjen black is 195-210:1, and the mass ratio of the ternary nickel-cobalt-manganese material to indium oxide is 45-60:1.

[0018] Furthermore, the calcination time of the low-temperature calcination process of 300-400°C is 4-6h, and the calcination time of the high-temperature calcination process of 500-650°C is 4-6h; the heating rate during calcination is 35-45°C / min, and the annealing rate is 15-25°C / min.

[0019] The third aspect of the present application provides a positive electrode sheet having a positive electrode material layer thereon, wherein the positive electrode material layer contains the positive electrode active material mentioned above.

[0020] The fourth aspect of the present application provides a battery comprising the above-mentioned positive electrode sheet.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention relates to doping indium oxide (In2O3) into a ternary nickel-cobalt-manganese material (NCM material). 2 O 3 ) and Ketjen black to form a modified ternary nickel-cobalt-manganese material, which has a core-shell structure with a double shell of a ternary nickel-cobalt-manganese material core, a Ketjen black coating layer inner shell and an indium oxide modified layer outer shell. The present application achieves synergistic optimization and improvement of the ternary nickel-cobalt-manganese material in terms of composition structure and performance.

[0023] The coating of Ketjen Black on the ternary nickel-cobalt-manganese material improves the conductivity of the traditional ternary nickel-cobalt-manganese material, and the performance of the material is improved by combining with the outer indium oxide modified layer; during calcination, indium oxide reacts with the Li 2 CO 3 Reacting with LiOH can not only reduce the amount of residual alkali on the surface of the material, but also form a layer of lithium indium oxide protective film on the surface of the material, which can improve the capacity attenuation problem caused by side reactions after long cycles of the material; after the lithium indium oxide protective film is formed, the residual alkali remaining on the surface reacts with the lithium indium oxide protective film, which will hinder the function of the lithium indium oxide protective film and affect the surface impedance of the material to a certain extent. However, the present application further modifies the surface impedance and conductive properties of the material through the Ketjen black coating layer on the inner side of the indium oxide modified layer, and finally obtains a modified ternary nickel-cobalt-manganese core-shell particle material with outstanding performance.

[0024] Compared with conventional ternary nickel-cobalt-manganese materials, the modified ternary nickel-cobalt-manganese core-shell particle material of the present application can significantly improve the cycle performance of lithium batteries. The scheme of the present application is applicable to a variety of positive electrode active materials such as medium-nickel ternary positive electrode materials, medium-high-nickel ternary positive electrode materials and high-nickel ternary nickel-cobalt-manganese materials, and the modification effect on high-nickel ternary nickel-cobalt-manganese materials is particularly significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 : Schematic diagram of the structure of the core-shell particles of the positive electrode active material of the present invention.

[0026] In the figure: 1-modified ternary nickel-cobalt-manganese core-shell particle material, 2-ternary nickel-cobalt-manganese material, 3-ketjen black coating layer, 4-indium oxide modified layer. DETAILED DESCRIPTION

[0027] The above contents of the present invention are further described in detail below in the form of specific implementation methods, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0028] The test methods used in the following examples are all conventional methods unless otherwise specified, and the reagents, methods and equipment used are all conventional reagents, methods and equipment in the art unless otherwise specified.

[0029] For the sake of simplicity, this document only specifically discloses some numerical values ​​and optional ranges. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range. Similarly, any upper limit can be combined with any other upper limit to form an unambiguous range; the optional items in the optional range can also be combined arbitrarily.

[0030] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art.

[0031] The invention provides a positive electrode active material. The positive electrode active material is a modified ternary nickel-cobalt-manganese material formed by adding indium oxide and ketjen black into a ternary nickel-cobalt-manganese material.

[0032] The modified ternary nickel-cobalt-manganese material is a core-shell particle material, the core is a ternary nickel-cobalt-manganese material, and the shell includes a two-layer structure of an inner shell and an outer shell; wherein the inner shell is a Ketjen black coating layer, and the outer shell is an indium oxide modified layer.

[0033] In some embodiments, the particle size D50 of the modified ternary nickel-cobalt-manganese material is in the range of 8-12 μm; the thickness of the Ketjen black coating layer is in the range of 1.0-3.8 μm, and the thickness of the indium oxide modified layer is in the range of 0.3-1.5 μm.

[0034] In some embodiments, the ternary nickel-cobalt-manganese material of the present invention is preferably an 8-series high-nickel ternary positive electrode material, such as NCM811, etc. However, the solution of the present invention is not limited to 8-series high-nickel ternary positive electrode materials, and can also be applied to 6-series medium-high nickel ternary positive electrode materials, such as NCM622, etc., and can also be applied to 5-series medium-nickel ternary positive electrode materials, such as NCM523, etc., all of which can achieve the effect of improving the cycle performance of lithium batteries, but the modification effect on 8-series high-nickel ternary positive electrode materials is more significant.

[0035] The present invention also provides a method for preparing a positive electrode active material, comprising the following steps:

[0036] During the low-temperature calcination process at 300-400° C., the Ketjen black powder is coated with the ternary nickel-cobalt-manganese material to form a primary particle material containing a ternary nickel-cobalt-manganese material core and a Ketjen black coating layer inner shell;

[0037] Then, during a high-temperature calcination process at 500-650°C, the indium oxide powder modifies the surface of the primary particle material to form a modified ternary nickel-cobalt-manganese core-shell particle material containing a ternary nickel-cobalt-manganese material core, a Ketjen black coating layer inner shell and an indium oxide modified layer outer shell.

[0038] In some embodiments, the calcination process is carried out in a protective atmosphere such as N 2 The mixed powder after grinding was transferred to a magnetic boat and reacted in a tube furnace.

[0039] However, the solution of the present invention is not limited to N 2 The reaction conditions in the atmosphere and the tubular furnace may be other gas atmospheres that do not participate in the reaction, and other devices that can achieve high-temperature calcination reactions.

[0040] Ketjen black powder and indium oxide powder are added in sequence. After adding Ketjen black powder to the ternary nickel-cobalt-manganese material, the temperature is raised to 300-400°C to form a Ketjen black coating layer, and then indium oxide powder is added and the temperature is raised to 500-650°C to prepare an indium oxide modified layer; or Ketjen black powder and indium oxide powder are added to the ternary nickel-cobalt-manganese material at the same time, and a programmed heating process of 300-400°C in the first stage and 500-650°C in the second stage is carried out to finally obtain a modified ternary nickel-cobalt-manganese core-shell particle material.

[0041] In some embodiments, the mass ratio of the ternary nickel-cobalt-manganese material to Ketjen black is 195-210:1, and the mass ratio of the ternary nickel-cobalt-manganese material to indium oxide is 45-60:1.

[0042] In some embodiments, the calcination time of the low-temperature calcination process of 300-400°C is 4-6h, and the calcination time of the high-temperature calcination process of 500-650°C is 4-6h; the heating rate during calcination is 35-45°C / min, and the annealing rate is 15-25°C / min.

[0043] The present invention also provides a positive electrode sheet having a positive electrode material layer, wherein the positive electrode material layer contains the positive electrode active material.

[0044] In some embodiments, the positive electrode slurry layer further contains a conductive agent and a binder. The ratio of the positive electrode active material to the conductive agent and the binder can be reasonably determined by those skilled in the art through experiments and experience.

[0045] The present invention also provides a battery, comprising the above-mentioned positive electrode sheet.

[0046] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments:

[0047] Embodiment 1:

[0048] (1) Preparation of modified ternary nickel-cobalt-manganese core-shell particle materials

[0049] Ketjen black powder was added to NCM811, and the mixture was ground and mixed until uniform. The mixture was transferred to a magnetic boat, and N2 was introduced into a tubular furnace. The mixture was heated to 350°C and calcined for 5 hours to form a Ketjen black coating layer. Then, indium oxide powder was added, the mixture was ground and mixed until uniform, and the mixture was heated to 600°C and calcined for 5 hours to prepare an indium oxide modified layer to obtain modified NCM811. The heating rate was 40°C / min, and the annealing rate was 20°C / min.

[0050] Among them, the mass ratio of NCM811 to Ketjen black is 200-205:1, and the mass ratio of NCM811 to In 2 O 3 The mass ratio is 50-55:1.

[0051] The particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 10 μm; the thickness of the Ketjen black coating layer is 2.4 μm, and the oxide

[0052] The thickness of the indium modified layer is 0.9 μm.

[0053] (2) Preparation of positive electrode slurry:

[0054] The positive electrode active material is NCM811 modified by the product obtained in step (1), the binder is PVDF (KF1100), and the conductive agent is Super P (Swiss Termeco); the mixture is stirred and mixed in a ratio of positive electrode active material: binder: conductive agent = 96:2:2, and after mixing evenly, it is coated on a 14um aluminum foil and dried in a vacuum drying oven at 130°C for 12h to obtain a positive electrode sheet.

[0055] (3) Assembly of button batteries:

[0056] The button battery shell uses the CR2032 model, the diaphragm uses a 20um diaphragm, and the electrode uses the above-mentioned positive electrode with a uniform coating. In a glove box filled with argon, the button battery is assembled in the following order: battery shell - placing the positive electrode - dripping the electrolyte - placing the diaphragm - dripping the electrolyte - placing the lithium sheet - placing the gasket spring - battery shell.

[0057] (4) Cycle performance test:

[0058] The button battery was tested for 100 cycles of 0.2C charge and discharge with a voltage range of 2.8-4.2 V using a button battery charge and discharge tester (Wuhan Blue Electric, CT2001A). The test results are shown in Table 1.

[0059] Embodiment 2:

[0060] The scheme of this embodiment is basically the same as that of embodiment 1, except that: NCM811 and In2 O 3 The mass ratio is 40-45:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 10.6μm; among them, the thickness of the Ketjen black coating layer is 2.4μm, and the thickness of the indium oxide modified layer is 1.5μm.

[0061] Embodiment 3:

[0062] The scheme of this embodiment is basically the same as that of embodiment 1, except that: NCM811 and In 2 O 3 The mass ratio is 45-50:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 10.3μm; among them, the thickness of the Ketjen black coating layer is 2.4μm, and the thickness of the indium oxide modified layer is 1.2μm.

[0063] Embodiment 4:

[0064] The scheme of this embodiment is basically the same as that of embodiment 1, except that: NCM811 and In 2 O 3 The mass ratio is 55-60:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 9.7μm; among them, the thickness of the Ketjen black coating layer is 2.4μm, and the thickness of the indium oxide modified layer is 0.6μm.

[0065] Embodiment 5:

[0066] The scheme of this embodiment is basically the same as that of embodiment 1, except that: NCM811 and In 2 O 3 The mass ratio is 60-65:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 9.4μm; among them, the thickness of the Ketjen black coating layer is 2.4μm, and the thickness of the indium oxide modified layer is 0.3μm.

[0067] Embodiment 6:

[0068] The scheme of this embodiment is basically the same as that of Example 1, except that: the mass ratio of NCM811 to Ketjen black is 190-195:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 11.4 μm; wherein the thickness of the Ketjen black coating layer is 3.8 μm, and the thickness of the indium oxide modified layer is 0.9 μm.

[0069] Embodiment 7:

[0070] The scheme of this embodiment is basically the same as that of Example 1, except that: the mass ratio of NCM811 to Ketjen black is 195-200:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 10.7 μm; wherein, the thickness of the Ketjen black coating layer is 3.1 μm, and the thickness of the indium oxide modified layer is 0.9 μm.

[0071] Embodiment 8:

[0072] The scheme of this embodiment is basically the same as that of Example 1, except that: the mass ratio of NCM811 to Ketjen black is 205-210:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 9.3 μm; wherein, the thickness of the Ketjen black coating layer is 1.7 μm, and the thickness of the indium oxide modified layer is 0.9 μm.

[0073] Embodiment 9:

[0074] The scheme of this embodiment is basically the same as that of Example 1, except that: the mass ratio of NCM811 to Ketjen black is 210-215:1, and the particle size D50 of the modified ternary nickel-cobalt-manganese core-shell particle material is 8.6 μm; wherein the thickness of the Ketjen black coating layer is 1.0 μm, and the thickness of the indium oxide modified layer is 0.9 μm.

[0075] Comparative Example 1:

[0076] Compared with Example 1, the scheme of this comparative example does not contain In in step 1. 2 O 3 The rest is the same as in Example 1.

[0077] Comparative Example 2:

[0078] Compared with Example 1, the scheme of this comparative example is that no Ketjen black is introduced in step 1, and the rest is the same as Example 1.

[0079] Comparative Example 3:

[0080] Compared with Example 1, the scheme of this comparative example does not have step 1, and the positive electrode active material in step 2 is replaced by traditional NCM811 material. The rest is the same as Example 1.

[0081] The present application carried out multiple sampling tests and then conducted test measurements according to the conditions of the above embodiments and comparative examples, and took the average of the measurement results under the conditions of the embodiments and comparative examples. The results are shown in Table 1:

[0082] Table 1 Comparison of test results of various embodiments and comparative examples

[0083] serial number 30-cycle performance 50-cycle performance 100-cycle performance Example 1 93.9％ 92.4％ 90.3％ Example 2 92.4％ 89.2％ 86.1％ Example 3 92.6％ 89.6％ 86.6％ Example 4 92.8％ 90.2％ 87.1％ Example 5 91.9％ 89.4％ 86.3％ Example 6 91.3％ 87.9％ 84.9％ Example 7 92.8％ 88.6％ 86.2％ Example 8 92.5％ 88.8％ 86.8％ Example 9 92.1％ 88.5％ 85.8％ Comparative Example 1 91.0％ 87.2％ 82.2％ Comparative Example 2 88.2％ 85.7％ 81.7％ Comparative Example 3 87.9％ 82.1％ 78.1％

[0084] In the embodiment of the present invention, indium oxide (In 2 O 3 ) and Ketjen black for comprehensive modification of ternary nickel-cobalt-manganese materials, In 2 O 3 During calcination, Li 2 CO 3Reacting with LiOH, the amount of residual alkali on the surface of the material is reduced, and a layer of lithium indium oxide protective film is formed on the surface of the material, which improves the capacity attenuation problem caused by side reactions after long cycles of the material, and further modifies the surface impedance and conductivity of the material through the Ketjen black coating layer on the inner side of the indium oxide modified layer, and finally obtains a modified ternary nickel-cobalt-manganese core-shell particle material with outstanding performance. By comparing each embodiment with comparative example 3, it can be seen that compared with conventional ternary nickel-cobalt-manganese materials, the modified positive electrode active material of the present invention can significantly improve the cycle performance of lithium batteries.

[0085] In the scheme of the present invention, when the modified doping amount of Ketjen black and indium oxide changes, the cycle performance of the product will change accordingly, and the core-shell particles of the positive electrode active material formed within a certain range are outstandingly effective in improving the cycle performance of lithium batteries. By comparing Examples 1-9, it can be seen that when the mass ratio of the ternary nickel-cobalt-manganese material to Ketjen black is 195-210:1, and the mass ratio of the ternary nickel-cobalt-manganese material to indium oxide is 45-60:1, good results can be obtained. When the mass ratio of the ternary nickel-cobalt-manganese material to Ketjen black is 200-205:1, and the mass ratio of the ternary nickel-cobalt-manganese material to indium oxide is 50-55:1, it is the optimal solution.

[0086] As mentioned above, indium oxide (In 2 O 3 ) and Ketjen black play different modification roles on the ternary nickel-cobalt-manganese material, but only when the two exist at the same time can they produce a significant and effective modification effect. By comparing the embodiments with comparative examples 1 and 2, it can be seen that the addition of indium oxide and Ketjen black can play a significant synergistic role in improving the battery cycle performance. When only Ketjen black or only indium oxide is used for modification, the improvement of the battery cycle performance is very limited.

[0087] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A positive electrode active material, characterized in that: The positive electrode active material is a modified ternary nickel-cobalt-manganese material formed by adding indium oxide and Ketjen black into the ternary nickel-cobalt-manganese material.

2. The positive electrode active material according to claim 1, characterized in that: The modified ternary nickel-cobalt-manganese material is a core-shell particle material, the core is a ternary nickel-cobalt-manganese material, and the shell comprises a two-layer structure of an inner shell and an outer shell; wherein the inner shell is a Ketjen black coating layer and the outer shell is an indium oxide modified layer.

3. The positive electrode active material according to claim 2, characterized in that: The particle size D50 of the modified ternary nickel-cobalt-manganese material is in the range of 8-12 μm; the thickness of the Ketjen black coating layer is in the range of 1.0-3.8 μm, and the thickness of the indium oxide modified layer is in the range of 0.3-1.5 μm.

4. The positive electrode active material according to claim 1, characterized in that: The ternary nickel-cobalt-manganese material is an 8-series high-nickel ternary positive electrode material.

5. A method for preparing a positive electrode active material, characterized in that: The following steps are involved: During the low-temperature calcination process at 300-400° C., the Ketjen black powder is coated with the ternary nickel-cobalt-manganese material to form a primary particle material containing a ternary nickel-cobalt-manganese material core and a Ketjen black coating layer inner shell; Then, during a high-temperature calcination process at 500-650° C., the surface of the primary particle material is modified by indium oxide powder to form a modified ternary nickel-cobalt-manganese core-shell particle material containing a ternary nickel-cobalt-manganese material core, a Ketjen black coating layer inner shell and an indium oxide modified layer outer shell.

6. The method for preparing the positive electrode active material according to claim 5, characterized in that: The Ketjen black powder and the indium oxide powder are added in sequence, and after the Ketjen black powder is added to the ternary nickel-cobalt-manganese material, the temperature is raised to 300-400°C to form a Ketjen black coating layer, and then the indium oxide powder is added and the temperature is raised to 500-650°C to prepare an indium oxide modified layer; or the Ketjen black powder and the indium oxide powder are added to the ternary nickel-cobalt-manganese material at the same time, and a programmed heating process of 300-400°C in the first stage and 500-650°C in the second stage is carried out to finally obtain a modified ternary nickel-cobalt-manganese core-shell particle material.

7. The method for preparing the positive electrode active material according to claim 5, characterized in that: The mass ratio of the ternary nickel-cobalt-manganese material to Ketjen black is 195-210:1, and the mass ratio of the ternary nickel-cobalt-manganese material to indium oxide is 45-60:

1.

8. The method for preparing a positive electrode active material according to claim 5, characterized in that: The calcination time of the low-temperature calcination process of 300-400°C is 4-6h, and the calcination time of the high-temperature calcination process of 500-650°C is 4-6h; the heating rate during calcination is 35-45°C / min, and the annealing rate is 15-25°C / min.

9. A positive electrode sheet, characterized in that: The positive electrode sheet has a positive electrode material layer, and the positive electrode material layer contains the positive electrode active material described in any one of claims 1 to 4 or prepared by the method described in any one of claims 5 to 8.

10. A battery, characterized in that: A positive electrode sheet comprising the positive electrode sheet according to claim 9.

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