Battery cell and preparation method therefor, positive electrode active material and preparation method therefor, positive electrode sheet, battery device and electric device

Abstract

Disclosed in the present application are a battery cell and a preparation method therefor, a positive electrode active material and a preparation method therefor, a positive electrode sheet, a battery device and an electric device. The battery cell comprises a positive electrode sheet, wherein the positive electrode sheet comprises a current collector and a positive electrode active material layer arranged on at least one side of the current collector, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material comprises an O3-type layered metal oxide; and in an X-ray diffraction pattern of the positive electrode active material, the ratio of the intensity of the (006) diffraction peak to the intensity of the (011) diffraction peak is less than or equal to 1. Therefore, the morphological characteristics of the positive electrode active material can be improved, and the tap density of the positive electrode active material and the compacted density of the positive electrode active material layer can be increased, thereby improving the energy density of the battery cell.

Description

Battery cell and preparation method thereof, positive electrode active material and preparation method thereof, positive electrode sheet, battery device, and electric device

[0001] Priority information

[0002] This application claims priority to and the benefit of Chinese Patent Application No. 202411389577.6, filed September 30, 2024, and is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the technical field of batteries, and specifically relates to a battery cell and a preparation method thereof, a positive electrode active material and a preparation method thereof, a positive electrode sheet, a battery device, and an electric device. BACKGROUND

[0004] Secondary batteries are not only applied to energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric cars, and electric transportation tools, military equipment, aerospace, and other fields. Sodium-ion batteries are a kind of secondary batteries, which mainly rely on the movement of sodium ions between the positive and negative electrodes to work. Transition metal oxides are commonly used positive electrode active materials for sodium-ion batteries. With the development of the current society, people have higher and higher requirements for batteries. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a positive electrode active material, which aims to improve the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer, and improve the energy density of the battery cell.

[0006] To achieve the above-mentioned purpose, the first aspect of the present application provides a battery cell, which comprises:

[0007] A positive electrode sheet, the positive electrode sheet comprises a current collector and a positive electrode active material layer provided on at least one side of the current collector, the positive electrode active material layer comprises a positive electrode active material, the positive electrode active material comprises a layered metal oxide in O3 phase; the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction pattern of the positive electrode active material is ≤1.

[0008] The positive electrode active material of the first aspect of the present application at least has the following beneficial effects: the morphology of the positive electrode active material can be improved, the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer are improved, and the energy density of the battery cell is improved.

[0009] In some embodiments of the present application, the positive electrode active material comprises Na x M1 y O2±z wherein 0.8≤x≤1.0, 0.95

[0010] In some embodiments of the present application, 0.85≤x≤0.9. Thereby the energy density of the positive active material layer and the battery cell can be further improved.

[0011] In some embodiments of the present application, M1 comprises Ni element, Fe element, Mn element, and at least one of Cu element, Zn element, and Ti element.

[0012] In some embodiments of the present application, the diffraction peak of the (006) crystal plane corresponds to a 2θ angle of 33°-34°, and the diffraction peak of the (011) crystal plane corresponds to a 2θ angle of 35°-36°. Thereby, the powder compaction density and the specific capacity of the obtained positive active material are both high, and the energy density of the battery cell can be improved.

[0013] In some embodiments of the present application, the ratio of the diffraction peak intensity of the (006) crystal plane to the diffraction peak intensity of the (011) crystal plane is 0.9-1.0. Thereby the energy density of the positive active material layer and the battery cell can be further improved.

[0014] In some embodiments of the present application, the powder compaction density of the positive active material under a pressure of 1 ton is 2.8 g / cm 3 -2.9 g / cm 3 . Thereby the positive active material layer has a high compaction density.

[0015] In some embodiments of the present application, the powder compaction density of the positive active material under a pressure of 2 tons is 3.1 g / cm 3 -3.2 g / cm 3 . Thereby the positive active material layer has a high compaction density.

[0016] In some embodiments of the present application, the powder compaction density of the positive active material under a pressure of 3 tons is 3.3 g / cm 3 -3.4 g / cm 3 . Thereby the positive active material layer has a high compaction density.

[0017] In some embodiments of the present application, the powder compaction density of the positive active material under a pressure of 4 tons is 3.4 g / cm3 ~3.5 g / cm 3 . Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density.

[0018] In some embodiments of the present application, the powder compaction density of the positive electrode active material under a pressure of 5 tons is 3.5 g / cm 3 ~3.6 g / cm 3 . Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density.

[0019] In some embodiments of the present application, the compaction density of the positive electrode active material layer is 3.2 g / cm 3 ~3.3 g / cm 3 . Thus, the energy density of the battery cell can be further improved.

[0020] In some embodiments of the present application, the Dv50 particle size of the positive electrode active material is 4 μm ~ 6 μm. Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density.

[0021] In some embodiments of the present application, the positive electrode active material includes Na x M1 y M2 e O 2±z , 0.8≤x≤1.0, 0.95 x M1 y O 2±z , 0.8≤x≤1.0, 0.95

[0022] The second aspect of the present application provides a positive electrode active material, which includes: an O3 phase layered metal oxide; and a ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction pattern of the positive electrode active material is ≤1. Thus, the morphology of the positive electrode active material can be improved, the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer can be improved, and the energy density of the battery cell can be improved.

[0023] In some embodiments of the present application, the positive electrode active material includes Na x M1 y O 2±z , 0.8≤x≤1.0, 0.95

[0024] In some embodiments of the present application, the positive electrode active material comprises Na x M1 y M2 e O 2±z wherein 0.8≤x≤1.0, 0.95

[0025] A third aspect of the present application provides a method for preparing a positive electrode active material, comprising: preparing precursor particles using a M1 source, M1 comprising one or more elements of Ni, Fe, Mn, Cu, Zn, Ti; mixing the precursor particles with a sodium source to perform a first calcination treatment, to obtain a positive electrode active material, wherein the molar ratio of Na element in the sodium source to M1 element in the M1 source is (0.8-1):(0.95-1); the positive electrode active material comprises an O3 phase layered metal oxide; the ratio of the diffraction peak intensity of the (006) crystal plane to the diffraction peak intensity of the (011) crystal plane in the X-ray diffraction pattern of the positive electrode active material is ≤1. Thereby, the morphology of the positive electrode active material can be improved, the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer can be improved, and the energy density of the battery cell can be further improved.

[0026] In some embodiments of the present application, the molar ratio of Na element in the sodium source to M1 element in the M1 source is (0.85-0.9):(0.95-1).

[0027] In some embodiments of the present application, the precursor particles are prepared using a M1 source and a M2 source, M2 comprising one or more elements of Li, Mg, Al, Zr, Ca, and the molar ratio of Na element in the sodium source, M1 element in the M1 source and M2 element in the M2 source is (0.8-1):(0.95-1):(0-0.05).

[0028] In some embodiments of the present application, the method for preparing a positive electrode active material further comprises: performing a second calcination treatment on the first calcination product, the temperature of the second calcination treatment being greater than the temperature of the first calcination treatment.

[0029] In some embodiments of the present application, the temperature of the first calcination treatment is 650-950°C, and the time is 5-20h.

[0030] In some embodiments of the present application, the temperature of the second calcination treatment is 700-1000°C, and the time is 5-20h.

[0031] The fourth aspect of the present application provides a positive electrode sheet, comprising the positive electrode active material of the second aspect of the present application or the positive electrode active material prepared by the method of the third aspect of the present application.

[0032] The fifth aspect of the present application provides a method for preparing a battery cell, comprising: mixing a positive electrode active material, a conductive agent and a binder with a solvent to obtain a positive electrode slurry; and coating the positive electrode slurry on at least one side of a current collector to obtain a positive electrode sheet, wherein the positive electrode active material comprises a layered metal oxide in O3 phase; and the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction pattern of the positive electrode active material is ≤1. The method can improve the morphology of the positive electrode active material, increase the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer, and further improve the energy density of the battery cell.

[0033] The sixth aspect of the present application provides a battery device, comprising the battery cell of the first aspect of the present application, or the positive electrode active material of the second aspect of the present application, or the positive electrode active material prepared by the method of the third aspect of the present application, or the positive electrode sheet of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application.

[0034] The seventh aspect of the present application provides a power consumption device, comprising the battery cell of the first aspect of the present application, or the electrode sheet of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application, or the battery device of the sixth aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0035] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the following drawings, in which:

[0036] FIG. 1 is a scanning electron microscope image of the positive electrode active material prepared in Example 1 of the present application.

[0037] FIG. 2 is a schematic structural diagram of a battery according to an embodiment of the present application.

[0038] FIG. 3 is a schematic structural diagram of a battery module according to an embodiment of the present application.

[0039] FIG. 4 is a schematic structural diagram of a battery pack according to an embodiment of the present application.

[0040] FIG. 5 is an exploded view of FIG. 4.

[0041] FIG. 6 is a schematic diagram of a power consumption device using the battery as a power source according to an embodiment of the present application.

[0042] FIG. 7 is an XRD pattern of the positive electrode active material prepared in Example 1 of the present application.

[0043] FIG. 8 is an XRD pattern of the positive electrode active material prepared in Comparative Example 1 of the present application.

[0044] FIG. 9 is an XRD pattern of the positive electrode active material prepared in Comparative Example 2 of the present application.

[0045] FIG. 10 is a scanning electron microscope image of the positive electrode active material prepared in Comparative Example 1 of the present application.

[0046] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0047] The present application will be further described with reference to the specific embodiments. It is to be understood that these embodiments are intended only to illustrate the application and not to limit its scope.

[0048] Reference in the specification to "an embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" or "in the embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment. It is explicitly contemplated that embodiments described with respect to one embodiment can be combined with features of another embodiment.

[0049] "Ranges" disclosed herein are used both as endpoints and as limitations of disclosed ranges. Ranges of values are provided as a separate embodiment. The endpoints of the ranges can be included or excluded. Any range of values can be combined with any other range of values to form a new range of values. Ranges of values are to be understood as being open-ended, unless it is specified otherwise. Any value within a range of values can be combined with any other value within the same range or within another range to form a new range of values.

[0050] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application, unless otherwise specified.

[0051] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application, unless otherwise specified.

[0052] If not particularly specified, all steps of the present application can be performed in sequence or randomly, preferably in sequence. For example, the method comprises steps S1 and S2, indicating that the method can comprise steps S1 and S2 in sequence, or steps S2 and S1 in sequence. For example, the method can further comprise step S3, indicating that step S3 can be added to the method in any order, for example, the method can comprise steps S1, S2 and S3, or steps S1, S3 and S2, or steps S3, S1 and S2, etc.

[0053] If not particularly specified, in the present application, the term "and / or" is only a description of the association relationship between the associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents an "or" relationship between the associated objects.

[0054] In the present application, the terms "a plurality of" and "a plurality of" refer to two or more.

[0055] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as understood by a person skilled in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing the specific embodiments of the present application, and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application are intended to cover non-exclusive inclusion. Unless otherwise specified, the terms used in the present application have the same meaning as generally understood by those skilled in the art. Unless otherwise specified, the values of the parameters mentioned in the present application can be measured by various measuring methods commonly used in the art (for example, the method can be tested according to the method given in the examples of the present application).

[0056] With the continuous promotion of the green environmental protection theme, the application of batteries has penetrated into all aspects of life, including vehicles, electronic devices, energy storage devices, etc. However, as the application of batteries continues to expand, people's requirements for batteries are also getting higher and higher. For example, sodium-ion batteries, which are expected to have high energy density. In addition to improving the capacity and voltage of active materials, the common way to improve the energy density of sodium-ion batteries is also closely related to the powder compaction density of active materials. At present, transition metal oxides are one of the popular positive electrode active materials in sodium-ion batteries, and the improvement of the powder compaction density of transition metal oxides is related to the compaction density of the positive electrode active material layer and the improvement of the volume energy density of the battery cell. The methods for improving the powder compaction density of the positive electrode active material in lithium-ion batteries mainly include the size control and size grading of particles, but due to the larger radius of sodium ions than lithium ions, the transition metal oxide positive electrode active material in sodium-ion batteries tends to grow along a specific crystal plane (such as the (003) crystal plane). The transition metal oxide in sodium-ion batteries generally has a plate-like morphology, and it is difficult to form a close packing between particles. That is, the effect of improving the powder compaction density of the transition metal oxide positive electrode active material in sodium-ion batteries by particle size control and size grading is very limited.

[0057] To solve the above problems, the application provides a battery cell, which comprises a positive electrode sheet, the positive electrode sheet comprises a current collector and a positive electrode active material layer arranged on at least one side of the current collector, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material comprises an O3 phase layered metal oxide. In the X-ray diffraction pattern of the positive electrode active material, the ratio of the diffraction peak intensity of the (006) crystal plane to the diffraction peak intensity of the (011) crystal plane is ≤1. It can be understood that the layered metal oxide comprises a transition metal element. In the sodium battery system, by adjusting the relative intensity of the (006) crystal plane and the (011) crystal plane diffraction peak of the O3 phase layered metal oxide positive electrode active material, the morphology characteristics of the positive electrode active material can be affected, the roundness and contact effect of the positive electrode active material particles can be changed, and then the powder compaction density of the positive electrode active material can be affected. In the application, the ratio of the diffraction peak intensity of the (006) crystal plane to the diffraction peak intensity of the (011) crystal plane of the positive electrode active material satisfies the given range, which can make the positive electrode active material particles relatively round, increase the contact area between the positive electrode active material particles, and improve the powder compaction density of the positive electrode active material particles and the compaction density of the positive electrode active material layer. Therefore, it is beneficial to obtain a higher battery cell energy density.

[0058] The battery cell disclosed in the embodiments of the present application can be used in various energy storage systems using the battery cell or a battery device comprising the battery cell as a power source or using the battery cell or the battery device comprising the battery cell as an energy storage element. The power consumption equipment can include, but is not limited to, mobile phones, tablets, notebook computers, electric toys, electric tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0059] The first aspect of the present application provides a battery cell, comprising a positive electrode tab, the positive electrode tab comprising a current collector and a positive electrode active material layer provided on at least one side of the current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising a layered metal oxide of O3 phase; the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction pattern of the positive electrode active material is ≤1.

[0060] At present, in the sodium battery system, the effect of improving the powder compaction density of the layered metal oxide positive electrode active material by particle size control and size particle grading is very limited. On this basis, it is expected to increase the contact between active material particles by changing the morphology characteristics of the layered metal oxide positive electrode active material, thereby improving the powder compaction density of the positive electrode active material and the energy density of the battery cell, but the morphology characteristics of the layered metal oxide positive electrode active material are closely related to the growth orientation of its crystal face, therefore, it is necessary to determine the crystal face which has a greater influence on the powder compaction density of the layered metal oxide positive electrode active material and the factors affecting the crystal growth orientation. Referring to FIG. 1, for the layered metal oxide of O3 phase, the diffraction intensity of the (006) crystal face and the (011) crystal face is closely related to the compaction density (FIG. 1 shows the approximate direction of the (006) crystal face and the (001) crystal face of the positive electrode active material prepared in Example 1 of the present application). In the present application, the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face of the positive electrode active material meets the above range, which can improve the smoothness of the positive electrode active material particles, increase the contact area of the positive electrode active material particles, improve the powder compaction density of the positive electrode active material, and thus obtain a higher energy density of the battery cell.

[0061] Therefore, the battery cell of the first aspect of the present application at least has the following beneficial effects: the morphology characteristics of the positive electrode active material can be improved, the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer can be improved, and thus the energy density of the battery cell can be improved.

[0062] For example, the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction pattern of the positive electrode active material can be 1, 0.98, 0.95, 0.92, 0.9, 0.88, 0.85, 0.82, 0.8, 0.75, 0.7, 0.65, 0.6, 0.5, 0.4, 0.3, or 0.2, etc.

[0063] In some embodiments of the present application, whether the O3 phase layered metal oxide exists in the positive electrode active material and the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face can be determined in combination with X-ray diffraction (XRD) analysis, and the element composition in the positive electrode active material can be qualitatively and quantitatively analyzed in combination with EDS energy spectrum analysis or inductively coupled plasma emission spectrometry (ICP) testing. For example, when the positive electrode active material is subjected to XRD testing, the following method can be referred to: CuKα ray is used as the radiation source, the ray wavelength is 1.5406 A, the scanning 2θ angle range is 15°-70°, the scanning rate is 4° / min, the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face is determined based on the diffraction peak condition in the obtained XRD pattern, and the matching relationship between the phase state of the positive electrode active material and the layered metal oxide is determined in combination with a standard card, etc. For example, after the positive electrode sheet is subjected to ion polishing sectioning, the element composition of the positive electrode active material particles in the section can be determined by using EDS energy spectrum analysis. For example, after the positive electrode sheet is subjected to ion polishing sectioning, the element composition of the positive electrode active material particles in the section can be determined by using EDS energy spectrum analysis.

[0064] In some embodiments of the present application, the positive electrode active material can include the O3 phase Na x M1 y O 2±z wherein 0.8≤x≤1.0, 0.95 x M1 y O 2±z This is beneficial to improve the specific capacity of the positive electrode active material, and for reference to FIG. 1, the O3 phase Na x M1 y O 2±z, the diffraction intensity of the (006) crystal face and the (011) crystal face is closely related to the compaction density thereof, and changing the content of sodium elements can regulate the growth orientation of the crystal, and reducing the content of sodium elements can reduce the relative intensity of the diffraction peaks of the (006) crystal face and the (011) crystal face, thereby affecting the morphology characteristics of the positive electrode active material, so that the particle smoothness of the positive electrode active material is relatively good, which can significantly improve the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer, thereby improving the energy density of the battery cell; and increasing the content of sodium elements can also increase the specific capacity of the positive electrode active material, which is also conducive to improving the energy density of the battery cell. In the present application, by selecting the Na x M1 y O 2±z , and the ratio of the diffraction peak intensity of the (006) crystal face of the positive electrode active material to the diffraction peak intensity of the (011) crystal face satisfies the above range, the powder compaction density and the specific capacity of the positive electrode active material can be well balanced, thereby obtaining a higher energy density of the battery cell.

[0065] In some embodiments of the present application, the Na x M1 y O 2±z , the value of x can be: 0.85≤x≤0.9. In this way, the positive electrode active material can further have a high specific capacity and a high powder compaction density, thereby being conducive to further improving the energy density of the positive electrode active material layer and the battery cell.

[0066] In some embodiments of the present application, the Na x M1 y O 2±z , M1 can include Ni elements, Fe elements, Mn elements, and at least one of Cu elements, Zn elements, and Ti elements. For example, M1 can include Ni elements, Fe elements, Mn elements, Zn elements, and Ti elements. For another example, M1 can include Ni elements, Fe elements, Mn elements, Zn elements, Ti elements, and Cu elements. In a sodium battery system, the specific capacity of the O3 phase transition metal oxide containing nickel-iron-manganese elements is relatively high, on this basis, the introduction of Zn elements can promote the redox process of Ni elements, further improving the specific capacity of the positive electrode active material; the introduction of Ti elements can improve the cycle stability of the positive electrode active material; the introduction of Cu elements can improve the structural stability of the positive electrode active material at high potential. In this way, M1 elements meet the selected type range, which is conducive to further improving the energy density of the battery cell and improving its electrochemical performance.

[0067] In some embodiments of the present application, the Na x M1 y O 2±zIn some embodiments, M1 can mainly contain Ni, Mn and Fe. For example, the molar content of Ni, Mn and Fe in M1 can be greater than the molar content of Cu, Zn and Ti. In this way, the electrochemical performance of the battery cell can be further improved while maintaining a high energy density of the battery cell.

[0068] In some embodiments of the application, in the X-ray diffraction pattern of the positive electrode active material, the diffraction peak of the (006) crystal plane can correspond to a 2θ angle of 33°-34°, such as 33°, 33.2°, 33.5°, 33.8° or 34°, etc.; the diffraction peak of the (011) crystal plane can correspond to a 2θ angle of 35°-36°, such as 35°, 35.2°, 35.5°, 35.8° or 36°, etc. In this way, the powder compaction density and specific capacity of the obtained positive electrode active material are both high, which can improve the energy density of the battery cell.

[0069] In some embodiments of the application, in the X-ray diffraction pattern of the positive electrode active material, the ratio of the diffraction peak intensity of the (006) crystal plane to the diffraction peak intensity of the (011) crystal plane can be 0.9-1.0. In this way, the positive electrode active material can have both a high specific capacity and a high powder compaction density, which is conducive to further improving the energy density of the positive electrode active material layer and the battery cell.

[0070] In some embodiments of the application, the powder compaction density of the positive electrode active material under a pressure of 1 ton can be 2.8 g / cm 3 -2.9 g / cm 3 , for example, 2.8 g / cm 3 , 2.81 g / cm 3 , 2.83 g / cm 3 , 2.84 g / cm 3 , 2.85 g / cm 3 , 2.86 g / cm 3 , 2.88 g / cm 3 or 2.9 g / cm 3 , etc. In this way, the positive electrode active material layer can have a high compaction density, which is conducive to further improving the energy density of the battery cell.

[0071] In some embodiments of the application, the powder compaction density of the positive electrode active material under a pressure of 2 tons can be 3.1 g / cm 3 -3.2 g / cm 3 , for example, 3.11 g / cm 3 , 3.12 g / cm 3 , 3.14 g / cm 3 , 3.15 g / cm 33.16 g / cm3 3 3.17 g / cm3 3 3.18 g / cm3 3 3.2 g / cm3 3 or the like. Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density, and thus it is beneficial to further increase the energy density of the battery cell.

[0072] In some embodiments of the present application, the powder compaction density of the positive electrode active material under a pressure of 3 tons can be 3.3 g / cm3 3 ~ 3.4 g / cm3 3 , for example, can be 3.31 g / cm3 3 , 3.32 g / cm3 3 , 3.34 g / cm3 3 , 3.35 g / cm3 3 , 3.36 g / cm3 3 , 3.37 g / cm3 3 , 3.38 g / cm3 3 , or 3.4 g / cm3 3 , etc. Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density, and thus it is beneficial to further increase the energy density of the battery cell.

[0073] In some embodiments of the present application, the powder compaction density of the positive electrode active material under a pressure of 4 tons can be 3.4 g / cm3 3 ~ 3.5 g / cm3 3 , for example, can be 3.41 g / cm3 3 , 3.42 g / cm3 3 , 3.43 g / cm3 3 , 3.44 g / cm3 3 , 3.45 g / cm3 3 , 3.46 g / cm3 3 , 3.47 g / cm3 3 , or 3.5 g / cm3 3 , etc. Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density, and thus it is beneficial to further increase the energy density of the battery cell.

[0074] In some embodiments of the present application, the powder compaction density of the positive electrode active material under a pressure of 5 tons can be 3.5 g / cm3 3 ~ 3.6 g / cm3 3 , for example, can be 3.51 g / cm3 3 , 3.52 g / cm3 3 , 3.53 g / cm3 3 , 3.55 g / cm3 3 , 3.57 g / cm33 3.58 g / cm3 3 3.59 g / cm3 3 3.6 g / cm3 3 3.61 g / cm3 C , etc. Thus, it is beneficial to make the positive electrode active material layer have a higher compaction density, and further beneficial to further improve the energy density of the battery cell.

[0075] In the present application, when testing the powder compaction density of the positive electrode active material, during the external force compression process, as the positive electrode active material particles move and deform, the particle voids are filled, the inter-particle contact area increases, the inter-atomic attractive force is generated, and the mechanical bonding effect between the particles is enhanced, thereby forming a compaction with a certain density. By adjusting different pressures, the powder compaction density of the positive electrode active material under different pressures can be calculated using the following formula: p C = m / V = m / (S x H), wherein: p C is the powder compaction density of the positive electrode active material, with a unit of g / cm 3 ; m is the mass of the test sample, with a unit of g; S is the bottom area of the mold, with a unit of cm 2 ; and H is the compaction thickness, with a unit of cm.

[0076] In some embodiments of the present application, the compaction density of the positive electrode active material layer in the positive electrode tab can be 3.2 g / cm 3 ~ 3.4 g / cm 3 , for example, can be 3.2 g / cm 3 , 3.22 g / cm 3 , 3.25 g / cm 3 , 3.28 g / cm 3 , 3.3 g / cm 3 , 3.32 g / cm 3 , 3.35 g / cm 3 , 3.38 g / cm 3 , or 3.4 g / cm 3 , etc. Thus, the energy density of the battery cell can be further improved. In the present application, when testing the compaction density of the positive electrode active material layer, after discharging the battery cell to the lower limit cutoff voltage, the following method is referred to: the positive electrode tab is disassembled from the battery cell, for example, a single-side coated positive electrode tab (if it is a double-side coated tab, the positive electrode active material layer on one side can be wiped off first), punched into a small round piece with an area of S1, weighed, recorded as M1, and its thickness H1 is measured. Then, the positive electrode active material layer of the above weighed positive electrode tab is wiped off, the weight of the positive electrode current collector is weighed, recorded as M0, and its thickness H0 is measured. The compaction density of the positive electrode active material layer = (M1-M0) / [S1 x (H1-H0)].

[0077] In some embodiments of the present application, the Dv50 particle size of the positive electrode active material can be 4-6 μm, for example, can be 4.2 μm, 4.3 μm, 4.4 μm, 4.6 μm, 4.8 μm, 5.0 μm, 5.2 μm, 5.5 μm, 5.8 μm or 6 μm, etc. Among them, the Dv50 particle size refers to the particle size corresponding to the cumulative volume distribution percentage of 50%. The Dv50 particle size of the positive electrode active material can be determined by referring to the standard GB / T 19077-2016 / ISO 13320:2009, using a laser particle size analyzer (Malvern Master Size 2000). The specific test process can include: taking an appropriate amount of sample to be tested (the sample concentration ensures that the light intensity is 8%-12%), adding 20 ml of deionized water, and ultrasonicating for 5 min (53 KHz / 120 W) to ensure that the sample is completely dispersed, and then measuring the sample according to the GB / T 19077-2016 / ISO 13320:2009 standard. Thus, the positive electrode active material has a suitable powder compaction density and specific surface area, which is further beneficial to the battery cell to have a higher energy density and better cycle performance.

[0078] In some embodiments of the present application, the positive electrode active material can include Na x M1 y M2 e O 2±z , 0.8≤x≤1.0, 0.95 x M1 y M2 e O 2±z , 0≤z≤0.05, 0≤e x M1 y O 2±z The type and content of M2 elements in Na

[0079] In some embodiments of the present application, 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 include 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.

[0080] In some embodiments of the present application, the positive active material layer can also optionally include at least one of a binder, a conductive agent, and other optional additives. Among them, the binder, conductive agent and additives can all be conventional choices in the art, for example, the conductive agent can include but is not limited to one or more of super-p carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers, and the binder can include but is not limited to one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB). These materials can all be obtained through commercial channels.

[0081] In some embodiments of the present application, the battery cell can refer to a battery that can be activated by charging after discharging to continue to use the active material.

[0082] It can be understood that the battery cell proposed in the present application can be a sodium ion battery.

[0083] Generally, the battery cell includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. During the charging and discharging process of the battery, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet and plays a role of isolation. The electrolyte plays a role of conducting ions between the positive electrode sheet and the negative electrode sheet.

[0084] [Negative electrode sheet]

[0085] In the battery, the negative electrode tab generally includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material. The negative electrode current collector can be a conventional metal foil or a composite current collector (e.g., a metal material can be disposed on a polymer substrate to form a composite current collector). As an example, the negative electrode current collector can be a copper foil. The negative electrode active material layer can also optionally include a binder and a conductive agent. The conductive agent is used to improve the electrical conductivity of the negative electrode active material layer, and the binder is used to firmly bond the negative electrode active material and the binder to the negative electrode current collector. The present application does not make specific limitations on the types of conductive agents and binders of the negative electrode tab, and they can be selected according to actual needs. As an example, the conductive agent can include, but is not limited to, at least one of super-p, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. As an example, the binder can include, but is not limited to, at least one of styrene butadiene rubber (SBR), styrene-butadiene rubber (SBCs), water-based acrylic resin, and carboxymethyl cellulose (CMC).

[0086] The negative electrode active material layer can also optionally include a thickening agent, such as carboxymethyl cellulose (CMC), etc. However, the present application is not limited thereto, and other materials that can be used as a thickening agent for a sodium-ion battery negative electrode tab can also be used.

[0087] In some embodiments of the present application, the battery cell of the first aspect of the present application can be a sodium metal battery, in which case the negative electrode active material can include, but is not limited to, metallic sodium. For example, the negative electrode active material can also be an alloy of metallic sodium and other various metal or non-metal elements.

[0088] In some embodiments of the present application, the battery cell of the first aspect of the present application can also be a negative electrode-free sodium metal battery. In this case, the negative electrode is only composed of a metal foil current collector, without sodium metal on its surface. During the cycle process, only sodium in the positive electrode is used, and sodium metal is precipitated and peeled off on the negative electrode side.

[0089] [Electrolyte]

[0090] The electrolyte can include an electrolyte salt and a solvent.

[0091] As an example, the electrolyte sodium salt can include, but is not limited to, at least one of sodium hexafluorophosphate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate, and sodium bis(trifluoromethylsulfonyl)imide.

[0092] As an example, the solvent can include, but is not limited to, 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).

[0093] 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 performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature performance of the battery, and an additive capable of improving low-temperature performance of the battery.

[0094] [Separator]

[0095] As the separator described above, the present application is not particularly limited, and any known porous structure separator having electrochemical stability and mechanical stability can be used according to actual needs. For example, the separator can include, but is not limited to, a single layer or a multi-layer film including at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0096] The shape of the battery cell is not particularly limited in the embodiments of the present application, and can be cylindrical, square, or any other shape. FIG. 2 is a battery cell 1 having a square structure as an example.

[0097] In some embodiments of the present application, the battery cell can include an outer package. The outer package is used to package the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0098] In some embodiments, the outer package can include a housing and a cover plate. The housing can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The housing has an opening communicating with the receiving cavity, and the cover plate can be arranged on the opening to close the receiving cavity.

[0099] The positive electrode sheet, the negative electrode sheet, and the separator can be wound or stacked to form an electrode assembly. The electrode assembly is packaged in the receiving cavity. The number of electrode assemblies contained in the battery cell can include one or several, which can be adjusted according to needs.

[0100] In some embodiments, the outer package of the battery cell can include a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell. The outer package of the battery can also include a soft package, such as a pouch soft package. The material of the soft package can be plastic, such as can include at least one of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS).

[0101] Based on the same inventive concept, the second aspect of the present application provides a positive electrode active material, comprising: a layered metal oxide in an O3 phase; and a ratio of a diffraction peak intensity of a (006) crystal plane to a diffraction peak intensity of a (011) crystal plane in an X-ray diffraction pattern of the positive electrode active material is ≤1. Thereby, the morphology of the positive electrode active material can be improved, the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer can be improved, and the energy density of the battery cell can be improved.

[0102] In some embodiments of the present application, the positive electrode active material comprises a Na x M1 y O 2±z , wherein 0.8≤x≤1.0, 0.95

[0103] In some embodiments of the present application, the positive electrode active material comprises a Na x M1 y M2 e O 2±z , wherein 0.8≤x≤1.0, 0.95

[0104] Wherein, the optional types of the positive electrode active material (including the optional general formula and the optional ranges of the components and the subscript value ranges, etc.), the diffraction peak intensity of the (006) crystal plane to the diffraction peak intensity of the (011) crystal plane in the positive electrode active material, the diffraction peak positions of the (006) crystal plane and the (011) crystal plane of the positive electrode active material, the powder compaction density of the positive electrode active material under different pressure conditions, the Dv50 particle size of the positive electrode active material, etc. have been described in detail in the foregoing part, and will not be repeated here.

[0105] Based on the same inventive concept, the third aspect of the present application provides a method for preparing a positive electrode active material, comprising: preparing precursor particles by using a M1 source, M1 comprising one or more elements of Ni, Fe, Mn, Cu, Zn, Ti; mixing the precursor particles with a sodium source to perform a first calcination treatment, to obtain a positive electrode active material, wherein the molar ratio of Na element in the sodium source to M1 element in the M1 source is (0.8-1):(0.95-1); the positive electrode active material comprises an O3 phase layered metal oxide; the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction pattern of the positive electrode active material is ≤1.

[0106] The relative content of sodium element and the type and composition of M1 element will affect the crystal structure of the prepared positive electrode active material. For the composition of M1 element, changing the content of sodium element can control the crystal growth orientation. Reducing the content of sodium element can reduce the relative intensity of the diffraction peaks of the (006) crystal face and the (011) crystal face, thereby affecting the morphology characteristics of the positive electrode active material, making the particle smoothness of the positive electrode active material relatively good, and thereby can significantly improve the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer, and improve the energy density of the battery cell. Increasing the content of sodium element can also increase the specific capacity of the positive electrode active material, which is also beneficial to improve the energy density of the battery cell. In the present application, based on the composition of M1 element, the content of Na element and M1 element satisfies the given range, which is more conducive to preparing the layered metal oxide Na x M1 y O 2±z , 0.8≤x≤1.0, 0.95

[0107] For example, the molar ratio of Na element in the sodium source to M1 element in the M1 source can be 0.8:1, 0.85:1, 0.82:1, 0.88:1, 0.9:1, 0.92:1, 0.95:1, 0.98:1, 1:1, 0.8:0.98, 0.85:0.98, 0.82:0.98, 0.88:0.98, 0.9:0.98, 0.92:0.98, 0.95:0.98, 0.98:0.98, 1:0.98, 0.8:0.95, 0.85:0.95, 0.82:0.95, 0.88:0.95, 0.9:0.95, 0.92:0.95, 0.95:0.95, 0.98:0.95, or 0.95:0.95, etc.

[0108] In some embodiments of the present application, the molar ratio of the Na element in the sodium source to the M1 element in the M1 source can be (0.85-0.95):(0.95-1), such as (0.85-0.93):(0.95-1) or (0.85-0.92):(0.95-1), etc. Alternatively, the molar ratio of the Na element in the sodium source to the M1 element in the M1 source can be (0.85-0.9):(0.95-1). This can further take into account the tap density and specific capacity of the prepared positive electrode active material, and thus a higher energy density of the battery cell can be obtained.

[0109] In some embodiments of the present application, the precursor particles can be prepared using the M1 source and the M2 source, the M2 can include one or more elements of Li, Mg, Al, Zr, Ca, and the molar ratio of the Na element in the sodium source, the M1 element in the M1 source, and the M2 element in the M2 source is (0.8-1):(0.95-1):(0-0.05), such as (0.8-1):0.95:0.05, (0.8-1):0.96:0.04, (0.8-1):0.97:0.03, (0.8-1):0.98:0.02, or (0.8-1):0.99:0.01, etc. This is conducive to preparing the O3 phase positive electrode active material Na x M1 y M2 e O 2±z wherein 0.8≤x≤1.0, 0.95

[0110] In some embodiments of the present application, the Na x M1 y O 2±zFor example, the precursor particles can be prepared by co-precipitation or mechanical ball milling. For example, in the case of co-precipitation, a water-soluble M1 source can be mixed with water, and the pH value of the mixture is adjusted to prepare precursor particles containing M1 elements; optionally, when M2 elements (M2 elements can include one or more of Li, Mg, Al, Zr, Ca) need to be doped in the precursor particles, the mixing can further include adding a water-soluble M2 source. For another example, in the case of mechanical ball milling, oxides of M1 elements are mixed and mechanically milled to obtain precursor particles containing M1 elements; optionally, when M2 elements need to be doped in the precursor particles, the mixing can further include adding oxides of M2 elements; further optionally, when the precursor particles are prepared by mechanical ball milling, the mixing can be high-speed mixing by a mixer, such as a bevel mixer; the rotation speed of the mechanical ball milling can be 10 rpm to 100 rpm, and the mixing time can be 1 h to 10 h; further optionally, the rotation speed of the mechanical ball milling can be 40 rpm to 60 rpm.

[0111] In some embodiments of the present application, when the precursor particles are mixed with a sodium source for the first calcination treatment, the O3 phase layered metal oxide, such as Na x M1 y O 2±z .

[0112] In some embodiments of the present application, after the precursor particles are mixed with a sodium source for the first calcination treatment, the first calcination product can be further subjected to a second calcination treatment, and the temperature of the second calcination treatment can be higher than that of the first calcination treatment. In this way, the raw material components can be first converted into metal oxides, and then the phase state of the metal oxides is converted to the O3 phase through secondary calcination to obtain the O3 phase layered metal oxide, such as Na x M1 y O 2±z .

[0113] In some embodiments of the present application, the first calcination process can have a temperature of 650 °C to 950 °C and a time of 5 h to 20 h, for example, the first calcination process can have a temperature of 650 °C, 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, or 950 °C, etc.; the first calcination process can have a time of 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, or 20 h, etc. In this way, the precursor particles of the M1 element can be promoted to transform into a layered metal oxide structure. Optionally, the atmosphere of the first calcination process can be an oxygen-containing atmosphere and / or an inert gas atmosphere, the oxygen-containing atmosphere can include, but is not limited to, an air atmosphere, an oxygen atmosphere, or an atmosphere mixing oxygen with other gases such as argon, the inert gas atmosphere can include, but is not limited to, an argon atmosphere. For example, the atmosphere of the first calcination process can be an air atmosphere or an oxygen atmosphere.

[0114] In some embodiments of the present application, the second calcination process can have a temperature of 700 °C to 1000 °C and a time of 5 h to 20 h, for example, the second calcination process can have a temperature of 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, 950 °C, or 1000 °C, etc.; the second calcination process can have a time of 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, or 20 h, etc. By making the temperature of the second calcination process greater than the temperature of the first calcination process and satisfying the above conditions, the layered metal oxide obtained by the first calcination process can be promoted to transform into an O3 phase. Optionally, the time of the second calcination process can be greater than the time of the first calcination process. Further optionally, the atmosphere of the second calcination process can be an oxygen-containing atmosphere and / or an inert gas atmosphere, the oxygen-containing atmosphere can include, but is not limited to, an air atmosphere, an oxygen atmosphere, or an atmosphere mixing oxygen with other gases such as argon, the inert gas atmosphere can include, but is not limited to, an argon atmosphere. For example, the atmosphere of the second calcination process can be an air atmosphere or an oxygen atmosphere.

[0115] In some embodiments of the present application, the Dv50 particle size of the obtained positive electrode active material can be adjusted by adjusting the particle size distribution of the precursor particles and / or the conditions of the first calcination process.

[0116] In some embodiments of the present application, the sodium source, the M1 source, and the M2 source can each independently be one or more of a metal, a carbonate, a bicarbonate, an oxalate, an acetate, a metal oxide, a metal hydroxide, a halide, a nitrate, and a sulfate.

[0117] It should be noted that the positive electrode active material of the second aspect of the present application, the method for preparing the positive electrode active material of the third aspect of the present application and the battery cell of the first aspect of the present application are based on the same inventive concept, and the features and effects described for the positive electrode active material in the battery cell of the first aspect of the present application are also applicable to the positive electrode active material of the second aspect of the present application and the method for preparing the positive electrode active material of the third aspect of the present application, which will not be repeated here.

[0118] The fourth aspect of the present application provides a positive electrode tab, which comprises the positive electrode active material of the second aspect of the present application or the positive electrode active material prepared by the method of the third aspect of the present application. It can be understood that the features and effects described for the positive electrode tab in the battery cell of the first aspect of the present application, the positive electrode active material of the second aspect of the present application and the method for preparing the positive electrode active material of the third aspect of the present application are also applicable to the positive electrode tab of the fourth aspect of the present application, which will not be repeated here.

[0119] Based on the same inventive concept, the fifth aspect of the present application provides a method for preparing a battery cell, which comprises: mixing a positive electrode active material, a conductive agent and a binder with a solvent to obtain a positive electrode slurry; and coating the positive electrode slurry on at least one side of a current collector to obtain a positive electrode tab, wherein the positive electrode active material comprises a layered metal oxide in an O3 phase; and the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction pattern of the positive electrode active material is ≤1. The method for preparing the battery cell of the second aspect of the present application and the battery cell of the first aspect of the present application are based on the same inventive concept, and the features and effects described for the battery cell of the first aspect of the present application are also applicable to the method for preparing the battery cell of the second aspect of the present application, which will not be repeated here. In general, the battery cell prepared by the method can improve the morphology of the positive electrode active material, increase the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer, and thus improve the energy density of the battery cell.

[0120] In some embodiments of the present application, the precursor particles can further comprise an M1 element, and the M1 element can comprise one or more of the following elements: Ni, Fe, Mn, Cu, Zn, Ti. Optionally, the precursor particles can further comprise an M2 element, and the M2 element can comprise one or more of the following elements: Li, Mg, Al, Zr, Ca. In this way, the cycle performance of the battery cell can be improved.

[0121] The sixth aspect of the present application provides a battery device comprising the battery cell of the first aspect of the present application, or the positive electrode active material of the second aspect of the present application, or the positive electrode active material prepared by the method of the third aspect of the present application, or the positive electrode plate of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application. In some embodiments, the battery device can be a battery cell, or a battery module or a battery pack assembled by the battery cell. The number of battery cells contained in the battery module or the battery pack can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module or the battery pack.

[0122] FIG. 3 is a battery module 2 as an example. Referring to FIG. 3, in the battery module 2, a plurality of battery cells 1 can be arranged in sequence along the length direction of the battery module 2. Of course, other arbitrary arrangements can also be used. Further, the plurality of battery cells 1 can be fixed by fasteners. The battery module 2 can also include a housing having an accommodation space, and the plurality of battery cells 1 can be accommodated in the accommodation space. In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0123] In some embodiments, the battery pack can include an accommodation space, and the plurality of battery cells can be directly accommodated in the accommodation space of the battery pack. Alternatively, the plurality of battery cells can be assembled into one or more battery modules, and the battery modules can be accommodated in the accommodation space of the battery pack.

[0124] FIGS. 4 and 5 are a battery pack 3 as an example. Referring to FIGS. 4 and 5, the battery pack 3 can include a battery box and a plurality of battery modules 2 arranged in the battery box, and the battery module 2 includes a plurality of battery cells 1. The battery box includes an upper box body 4 and a lower box body 5, and the upper box body 4 can be covered on the lower box body 5 to form a closed space for accommodating the battery module 2. The plurality of battery modules 2 can be arranged in the battery box in any manner.

[0125] The seventh aspect of the present application provides a power consumption device comprising the battery cell of the first aspect of the present application, or the electrode plate of the fourth aspect of the present application, or the battery cell prepared by the method of the fifth aspect of the present application, or the battery device of the sixth aspect of the present application.

[0126] Specifically, the battery cell or battery device can serve as a power source of the power consuming device, or as an energy storage unit of the power consuming device. The power consuming device can include, but is not limited to, a mobile device (e.g., a mobile phone, a laptop), an electric vehicle (e.g., 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.

[0127] FIG. 6 is a power consuming device as an example. The power consuming device includes a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. The power consuming device as another example can include a mobile phone, a tablet computer, a laptop. The power consuming device generally requires thinning, and a battery cell can be used as a power source.

[0128] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are intended to explain the present application only, and are not to be understood as limiting the present application. In the embodiments, the specific techniques or conditions not mentioned are performed according to the techniques or conditions described in the literature in the art or according to the product manual. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained commercially.

[0129] Example 1

[0130] (1) Positive active material

[0131] a) Nickel oxide, iron oxide, manganese oxide, zinc oxide, copper oxide, titanium dioxide were placed in a mixer according to a predetermined ratio for mechanical ball milling at a speed of 40-60 rpm for 4 h to obtain precursor particles;

[0132] b) The obtained precursor particles were mixed with sodium carbonate and placed in an air atmosphere at 800°C for calcination for 10 h;

[0133] c) The calcination product obtained in step b) was sieved and subjected to secondary calcination at 900°C in an air atmosphere for 15 h to obtain an O3 phase positive active material (see Table 1 for elemental composition).

[0134] (2) Positive electrode sheet: The prepared positive active material, nanoscale conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were mixed uniformly at a mass ratio of 94:3:3 with a solvent NMP by stirring, and then coated on both sides of an aluminum foil with a thickness of 13 μm to obtain a positive electrode sheet. The positive electrode sheet was dried, cold-pressed, and the coating surface density of the positive electrode sheet was 0.033 g / cm 2 .

[0135] (3) Preparation of the negative electrode sheet: after the negative electrode active material hard carbon, nanoscale conductive agent acetylene black, binder styrene-butadiene rubber (SBR), thickening agent sodium carboxymethyl cellulose (CMC) are mixed uniformly in the deionized water solvent system according to the weight ratio of 95:2:2:1, the two sides of the copper foil with a thickness of 6 μm are coated with the mixture, and then the coated copper foil is dried, cold-pressed (3 tons of pressure) to obtain the negative electrode sheet. The coating surface density of the negative electrode sheet is 0.0152 g / cm 2 .

[0136] (4) Electrolyte: organic solvent is obtained by mixing ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC) and the like in equal volume, and NaPF6 is dissolved in the organic solvent to prepare an electrolyte with a NaPF6 concentration of 1 mol / L.

[0137] (5) Separating membrane: porous polyethylene membrane with a thickness of 12 μm.

[0138] (6) Preparation of the battery

[0139] The above positive electrode sheet, separating membrane and negative electrode sheet are stacked in order, the separating membrane is arranged between the positive electrode sheet and the negative electrode sheet to play a separating role, and the above prepared electrolyte is added, so that the preparation of the battery is completed.

[0140] The positive electrode sheet, separating membrane and negative electrode sheet are stacked in order, the separating membrane is arranged between the positive electrode sheet and the negative electrode sheet to play a separating role, and the above prepared electrolyte is added, so that the preparation of the battery is completed.

[0141] Examples 2-10 and Comparative Examples 1-4

[0142] Examples 2-10 and Comparative Examples 1-4 are different from Example 1 in that the raw material ratio is different in the preparation process, and the element composition and related test results of the prepared positive electrode active material are also different, as shown in Tables 1-3.

[0143] Test:

[0144] i) XRD test: CuKα ray is used as the radiation source, the wavelength of the ray is The scanning 2θ angle range is 10°-70°, the scanning rate is 2° / min, and the diffraction peaks obtained from the XRD pattern are combined with the standard card to judge the matching relationship, diffraction peak position and relative intensity of the prepared positive electrode active material and metal oxide Na x M1 y O 2±z .

[0145] ii) ICP test: according to EPA 6010D-2014, the prepared positive electrode active material sample is treated by chemical method to be digested into solution, then atomized into plasma to be excited to emit characteristic spectrum of elements, and the element composition in the prepared positive electrode active material is qualitatively or quantitatively analyzed according to the wavelength and intensity (proportional to concentration) of the spectrum.

[0146] iii) Powder compaction density of positive electrode active material: the positive electrode active material is placed in a mold, a certain pressure is applied to obtain a compaction with a certain density, and the powder compaction density of the positive electrode active material is calculated by the following formula: p C = m / V = m / (S x H), wherein: p C is the powder compaction density of the positive electrode active material, with the unit of g / cm 3 ; m is the mass of the test sample, with the unit of g; S is the bottom area of the mold, with the unit of cm 2 ; H is the compaction thickness, with the unit of cm.

[0147] iv) Micro-morphology test: the micro-morphology of the positive electrode active material sample is tested by a scanning electron microscope (SEM).

[0148] v) Charge-discharge capacity test:

[0149] At 25°C, ① charged at a current of 0.33C to 4.2V, then charged at 4.2V to a current of 0.05C, and the charge capacity C1 was recorded; ② rested for 5 min; ③ discharged at a current of 1C to 1.5V, and the discharge capacity D1 was recorded, and the energy was recorded as E1 (unit: Wh).

[0150] vi) Energy density test: the energy density of the single cell = E1 / mass of the single cell.

[0151] The above-mentioned related tests were carried out on Examples 1-10 and Comparative Examples 1-4, and the test results are shown in Tables 2, 3, and Figures 1 and 7-10.

[0152] Table 1 Differences between the positive electrode active materials prepared in Examples 1-10 and Comparative Examples 1-4

[0153] Table 2 Other differences and test results of Examples 1-9 and Comparative Examples 1-4

[0154] Table 3 Test results of Example 1 and Example 10

[0155] Results and conclusions:

[0156] As can be seen from Examples 1 to 10, Comparative Examples 1 to 4, Table 1, Figure 1, Figures 7 to 10, the ratio of the peak intensity of the diffraction peak of the (006) crystal plane to the peak intensity of the diffraction peak of the (011) crystal plane in the XRD pattern of the metal oxide positive electrode active material of the O3 phase is controlled to be less than 1, which can improve the powder compaction density of the positive electrode active material and the compaction density of the positive electrode active material layer, and improve the energy density of the battery cell. Figure 1 is a scanning electron microscope image of the positive electrode active material prepared in Example 1, Figure 10 shows a scanning electron microscope image of the positive electrode active material prepared in Example 10, and Figures 7, 8 and 9 are, in turn, XRD patterns of the positive electrode active material prepared in Example 1, Comparative Example 1 and Comparative Example 2. As can be seen from the XRD pattern and the scanning electron microscope image of the positive electrode active material in Example 1 and Comparative Example 1, the ratio of the peak intensity of the diffraction peak of the (006) crystal plane to the peak intensity of the diffraction peak of the (011) crystal plane in the XRD pattern of the positive electrode active material prepared in Example 1 is relatively low, and the positive electrode active material particles are relatively smooth and have less sharp corners than the positive electrode active material particles prepared in Comparative Example 1. Further, as can be seen from the test results of Example 1 and Comparative Example 1, the powder compaction density of the positive electrode active material prepared in Example 1 and the compaction density of the positive electrode active material layer formed therefrom are both higher than those of Comparative Example 1. Further, as can be seen from the other examples and comparative examples, controlling the ratio of the peak intensity of the diffraction peak of the (006) crystal plane to the peak intensity of the diffraction peak of the (011) crystal plane in the XRD pattern of the metal oxide positive electrode active material of the O3 phase to be less than 1 can improve the particle morphology of the positive electrode active material, improve the powder compaction density of the positive electrode active material particles and the compaction density of the positive electrode active material layer, and improve the energy density of the battery cell. In addition, as can be seen from Example 1, Example 2 and Example 8, Example 9, doping Cu elements, Zn elements or Ti elements in the positive electrode active material is beneficial to further improving the energy density of the battery cell. As can be seen from Example 1 and Example 10, doping other elements (such as Ca elements) in the positive electrode active material is beneficial to further improving the cycle performance of the battery cell.

[0157] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions described in the foregoing examples can still be modified, or some or all of the technical features thereof can be replaced by equivalents. Such 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, and should be covered in the scope of the claims and the specification of the present application. In particular, the technical features mentioned in each of the embodiments can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific examples disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, wherein, The positive electrode tab comprises a current collector and a positive electrode active material layer provided on at least one side of the current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising a layered metal oxide of O3 phase; and the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction spectrum of the positive electrode active material is ≤1. M1 comprises Ni element, Fe element, Mn element, and at least one of Cu element, Zn element, and Ti element.

2. The battery cell of claim 1, wherein, The positive active material includes Na of O3 phase x M1 y O 2±z wherein 0.8≤x≤1.0, 0.95 y≤1.0, 0≤z≤0.05, M1 includes one or more elements of Ni, Fe, Mn, Cu, Zn, Ti.

3. The battery cell of claim 2, wherein, 0.85≤x≤0.9。 4. The battery cell of claim 2 or 3, wherein, The diffraction peak of the (006) crystal face corresponds to a 2θ angle of 33°-34°, and the diffraction peak of the (011) crystal face corresponds to a 2θ angle of 35°-36°.

5. The battery cell according to any one of claims 1 to 4, wherein, The ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face is 0.9-1.

0.

6. The battery cell of any one of claims 1-5, wherein, At least one of the following conditions is met:

7. The battery cell according to any one of claims 1 to 6, wherein, The Dv50 particle size of the positive electrode active material is 4 μm-6 μm. The positive electrode active material has a powder compaction density of 2.8 g / cm 3 ~ 2.9 g / cm 3 ; The positive electrode active material has a powder compaction density of 3.1 g / cm 3 ~ 3.2 g / cm 3 ; The positive electrode active material has a powder compaction density of 3.3 g / cm 3 ~ 3.4 g / cm 3 ; The positive electrode active material has a powder compaction density of 3.4 g / cm 3 ~ 3.5 g / cm 3 ; The positive electrode active material has a powder compaction density of 3.5 g / cm 3 ~ 3.6 g / cm 3 .

8. The battery cell of any one of claims 1-7, wherein, The compacted density of the positive electrode active material layer is 3.2 g / cm 3 ~ 3.4 g / cm 3 .

9. The battery cell of any one of claims 1-8, wherein, The positive electrode active material comprises a layered metal oxide of O3 phase; and the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction spectrum of the positive electrode active material is ≤1.

10. The battery cell of any one of claims 1-9, wherein, The positive active material includes Na of O3 phase x M1 y M2 e O 2±z wherein 0.8≤x≤1.0, 0.95 M1 includes one or more elements of Ni, Fe, Mn, Cu, Zn, Ti, and M2 includes one or more elements of Li, Mg, Al, Zr, Ca.

11. A positive electrode active material, wherein, The method comprises the following steps:

12. The positive electrode active material according to claim 11, wherein Na including O3 phase x M1 y O 2±z wherein 0.8≤x≤1.0, 0.95 y≤1.0, 0≤z≤0.05, M1 includes one or more elements of Ni, Fe, Mn, Cu, Zn, Ti.

13. The positive electrode active material according to claim 11 or 12, wherein Na including O3 phase x M1 y M2 e O 2±z wherein 0.8≤x≤1.0, 0.95 M1 includes one or more elements of Ni, Fe, Mn, Cu, Zn, Ti, and M2 includes one or more elements of Li, Mg, Al, Zr, Ca.

14. A method for producing a positive electrode active material, wherein, A precursor particle is prepared by using an M1 source, M1 comprising one or more elements of Ni, Fe, Mn, Cu, Zn, and Ti; The precursor particle is mixed with a sodium source to perform a first calcination treatment, to obtain a positive electrode active material, The molar ratio of Na element in the sodium source to M1 element in the M1 source is (0.8-1):(0.95-1); the positive electrode active material comprises a layered metal oxide of O3 phase; and the ratio of the diffraction peak intensity of the (006) crystal face to the diffraction peak intensity of the (011) crystal face in the X-ray diffraction spectrum of the positive electrode active material is ≤1. The molar ratio of Na element in the sodium source to M1 element in the M1 source is (0.85-0.9):(0.95-1); and / or, 15. The method of claim 14, wherein, A precursor particle is prepared by using an M1 source and an M2 source, M2 comprising one or more elements of Li, Mg, Al, Zr, and Ca; and the molar ratio of Na element in the sodium source, M1 element in the M1 source, and M2 element in the M2 source is (0.8-1):(0.95-1):(0-0.05). The method further comprises the following steps:

16. The method of claim 14 or 15, wherein, The first calcination product is subjected to a second calcination treatment, and the temperature of the second calcination treatment is higher than that of the first calcination treatment. The temperature of the first calcination treatment is 650°C-950°C, and the time is 5 h-20 h; and / or, 17. The method of claim 16, wherein, The temperature of the second calcination treatment is 700°C-1000°C, and the time is 5 h-20 h. The method comprises the following steps:

18. A positive electrode sheet, wherein, A positive electrode active material, a conductive agent, and a binder are mixed with a solvent to obtain a positive electrode slurry; 19. A method of making a battery cell, wherein, The positive electrode slurry is coated on at least one side of a current collector to obtain a positive electrode tab, ​ ​ The positive electrode active material comprises a layered metal oxide of O3 phase; and a ratio of a diffraction peak intensity of a (006) crystal face to a diffraction peak intensity of a (011) crystal face in an X-ray diffraction pattern of the positive electrode active material is less than or equal to 1.

20. A battery device, wherein, Comprising: The battery cell of any one of claims 1 to 9, or the positive electrode plate of claim 18, or the battery cell made using the method of claim 19.

21. An electrical device, comprising: Comprising: The battery cell of any one of claims 1 to 9, or the battery cell made using the method of claim 19, or the battery device of claim 20.

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