Battery monomer, battery device, power utilization device and energy storage device

Abstract

The embodiment of the invention provides a battery monomer, a battery device, a power utilization device and an energy storage device. The battery monomer comprises a positive pole piece, the positive pole piece comprises a positive pole current collector and a positive pole film layer arranged on at least one side of the surface of the positive pole current collector, the positive pole film layer comprises a positive pole active material, the positive pole active material comprises layered transition metal oxide particles, the layered transition metal oxide particles comprise components with the general formula of LiaMbOc, 0.8 < = a < = 1.3, 0.8 < b < = 1, 1.5 < c < = 2, m comprises one or more of Ni, Co, Mn and Al; in a cross section of the layered transition metal oxide particles, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particles. The battery monomer has good thermal safety performance and relatively high energy density.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery device, an electrical device, and an energy storage device. Background Art

[0002] As market demands for longer driving range in electric devices increase, higher energy density requirements are also being placed on battery cells. To meet these demands for long driving range and high efficiency, high-energy-density cathode materials are widely adopted. However, these materials often suffer from insufficient thermal safety performance under extreme operating conditions, such as high temperatures, which can easily lead to thermal runaway and pose safety risks. Therefore, achieving both improved energy density and thermal safety performance remains a critical challenge in current battery material technology. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems in the background art. To this end, one object of the present application is to provide a battery cell, a battery device, an electrical device, and an energy storage device to improve the thermal safety performance of high-capacity positive electrode active materials.

[0004] The first embodiment of the present application provides a battery cell, wherein the battery cell includes a positive electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the surface of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes layered transition metal oxide particles, and the layered transition metal oxide particles include a general formula of Li a M b O c wherein 0.8≤a≤1.3, 0.8<b≤1, 1.5<c≤2, and M comprises one or more of Ni, Co, Mn, and Al; and in a cross section of the layered transition metal oxide particle, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particle.

[0005] To meet the demands of high battery life and high efficiency, high-energy-density cathode materials, such as layered transition metal oxides, are widely used. However, these materials often suffer from insufficient thermal safety performance under extreme operating conditions, such as high temperatures, which can easily lead to thermal runaway. Specifically, research has shown that at high temperatures (160°C-250°C), lithium ion release reduces the stability of the chemical bond (MO bond) between the M and O elements. Consequently, layered transition metal oxides in the lithium-ion-free state readily release oxygen. This released oxygen reacts with the electrolyte, the lithium in the negative electrode, and the negative electrode active material, generating a large amount of heat and causing thermal runaway.

[0006] The applicant's research found that by "the molar ratio of Li element to M element near the surface of the cross-section of the layered transition metal oxide particle is greater than the molar ratio of Li element to M element near the center of the particle", the battery cell can have high energy density and good thermal safety performance at the same time. Although the mechanism is not clear yet, experiments show that this may be related to the surface lithium replenishment of the layered transition metal oxide particles. The lithium ion release rate in the surface area of ​​the particle is faster, more lithium ions are released, and the oxygen release problem is more serious. Therefore, by increasing the molar ratio of Li element to M element in the surface area of ​​the particle, with the help of in-situ lithium replenishment of the surface area of ​​the particle that is deeply delithiated, the stability of the MO bond is improved, and then the oxygen release temperature of the positive electrode active material is increased, thereby improving the thermal safety performance of the high-capacity positive electrode active material, and achieving a balance between thermal safety performance and high energy density of the battery cell.

[0007] In some embodiments, a coating layer is further provided on the surface of the layered transition metal oxide particles, and the coating layer includes a solid electrolyte.

[0008] In some embodiments, the coating layer disposed on the surface of the layered transition metal oxide particles can intercept oxygen released from the layered transition metal oxide particles to a certain extent, further improving the thermal safety performance of the battery cell.

[0009] In some embodiments, the coating layer on the surface of the layered transition metal oxide particles can replenish lithium to the layered transition metal oxide particles under high temperature, thereby improving the thermal safety performance of the battery cell. However, lithium-replenishing materials often have poor ionic conductivity, sacrificing the battery's kinetic performance. The embodiments of the present application creatively discovered a solid electrolyte material that can replenish lithium. Using it as a coating layer for the layered transition metal oxide, it improves the thermal safety performance of the battery cell while also taking into account the battery's kinetic performance.

[0010] In some embodiments, the solid electrolyte includes one or more of lithium aluminum titanium phosphate oxide, lithium aluminum phosphate oxide, and tantalum-doped lithium lanthanum zirconium oxide.

[0011] In some embodiments, the general formula of the tantalum-doped lithium lanthanum zirconium oxide is as shown in Formula I, Li 6.4 La3Zr y1 Ta y2 O 12 , 0<y1<2 and 0<y2<2 Formula I.

[0012] In some embodiments, the general formula of the lithium aluminum titanium phosphate oxide is as shown in Formula II, Li x1 Al x2 Ti x3(PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 Formula II; the lithium aluminum phosphate oxide is Li3Al2(PO4)3.

[0013] The applicant's research has found that when the solid electrolyte is selected from the above range, it not only has good ionic conductivity, which can improve the thermal safety performance of the battery cell while taking into account the kinetic performance, but also has a good lithium replenishment effect, that is, it can replenish lithium for deeply delithiated layered transition metal oxides at high temperatures, improve the stability of the MO bond, and then increase the oxygen release temperature of the positive electrode active material, thereby achieving a balance between the thermal safety performance, kinetic performance and high energy density of the battery cell.

[0014] In some embodiments, the coating layer has a thickness of 0.02 μm to 2 μm.

[0015] In the embodiment of the present application, when the thickness of the coating layer is within the above range, the thermal safety performance of the battery cell can be further improved.

[0016] In some embodiments, the layered transition metal oxide particles are doped with La, Zr, and Ta.

[0017] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by doping the above elements.

[0018] In some embodiments, in a cross section of the layered transition metal oxide particle, the mass contents of La, Zr, and Ta near the surface are respectively greater than the mass contents of La, Zr, and Ta near the center.

[0019] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0020] In some embodiments, the layered transition metal oxide particles are doped with Al, Ti, and P, and M includes one or more of Ni, Co, and Mn.

[0021] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by doping the above elements.

[0022] In some embodiments, in a cross section of the layered transition metal oxide particle, the mass contents of Al, Ti, and P near the surface are respectively greater than the mass contents of Al, Ti, and P near the center.

[0023] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0024] In some embodiments, the layered transition metal oxide particles are doped with Al, Ti, and P, wherein in a cross section of the layered transition metal oxide particles, the molar ratio of Li to P near the surface is greater than the molar ratio of Li to P near the center.

[0025] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0026] In some embodiments, the layered transition metal oxide particles are doped with Al, Ti, and P, and M includes one or more of Ni, Co, and Mn, wherein in a cross section of the layered transition metal oxide particles, the molar ratio of Al to Ti near the surface is greater than the molar ratio of Al to Ti near the center.

[0027] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0028] In some embodiments, in a cross section of the layered transition metal oxide particle, in an outer region of 1 μm-3 μm from the surface toward the geometric center, the molar ratio of Al element, Ti element, and P element is (1-2):(0-1):3:3.

[0029] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0030] In some embodiments, in a cross section of the layered transition metal oxide particle, in a core region with a diameter of 3 μm-10 μm and a circle centered at the geometric center, the molar ratio of Al element, Ti element, and P element is (0.2-1):(1-1.8):3.

[0031] In the embodiments of the present application, the distribution of elements within the above range further improves the thermal safety and dynamic performance of the battery cells. Furthermore, since the core region has a relatively low degree of oxygen release, there is no need for doping with high-lithium-content lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide, thereby reducing production costs.

[0032] In some embodiments, in the cross-section of the layered transition metal oxide particles, in a core region with a diameter of 3 μm-7 μm with the geometric center as the center, the molar ratio of Al element, Ti element and P element is (0.2-0.8):(1.2-1.8):3; in an outer region of 1 μm-3 μm from the surface to the geometric center, the molar ratio of Al element, Ti element and P element is (1.2-2):(0-0.8):3; the thickness of the middle region between the core region and the outer region is 1 μm-3 μm, and in the middle region, the molar ratio of Al element, Ti element and P element is (0.8-1.2):(0.8-1.2):3.

[0033] In the embodiments of the present application, the distribution of elements within the above range further improves the thermal safety and dynamic performance of the battery cells. Furthermore, since the core and intermediate regions have relatively low oxygen release, there is no need for doping with lithium-rich lithium aluminum titanium phosphate or lithium aluminum phosphate, thereby reducing production costs.

[0034] In some embodiments, the Dv50 of the positive electrode active material is 10 μm-15 μm.

[0035] In the embodiments of the present application, when the Dv50 of the positive electrode active material is within the above range, the dynamic performance of the battery cell can be further improved while ensuring the thermal safety performance.

[0036] An embodiment of the second aspect of the present application provides a method for preparing a positive electrode active material, comprising: coating layered transition metal oxide particles with a solid electrolyte to obtain a coated product; sintering the coated product once to obtain a positive electrode active material; the solid electrolyte comprises one or more of lithium aluminum titanium phosphate oxide, lithium aluminum phosphate oxide, and tantalum-doped lithium lanthanum zirconium oxide.

[0037] In the embodiments of the present application, the positive electrode material prepared by the above method has good thermal safety performance, kinetic performance and high energy density. Although the mechanism is not clear yet, experiments show that this may be because the first sintering not only makes the coating layer stably coated on the surface of the particles, but also replenishes lithium on the surface of the particles, so that in the cross section of the layered transition metal oxide particles, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particle; in some cases, the solid electrolyte can also diffuse into the interior of the particles through the solid phase, further improving the lithium replenishment effect of the solid electrolyte on the layered transition metal oxide particles, thereby improving the thermal safety performance of the high energy density positive electrode active material. In addition, the solid electrolyte used has a high ionic conductivity, which achieves a good balance between thermal safety performance, kinetic performance and high energy density.

[0038] In some embodiments, the general formula of the tantalum-doped lithium lanthanum zirconium oxide is as shown in Formula I, Li 6.4 La3Zr y1 Ta y2 O 12 , 0<y1<2 and 0<y2<2 Formula I.

[0039] In some embodiments, the general formula of the lithium aluminum titanium phosphate oxide is as shown in Formula II, Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 Formula II; the lithium aluminum phosphate oxide is Li3Al2(PO4)3.

[0040] The applicant's research has found that when the solid electrolyte is selected from the above range, it not only has good ionic conductivity, which can improve the thermal safety performance of the battery cell while taking into account the kinetic performance, but also has a good lithium replenishment effect, that is, at high temperature, it replenishes lithium for the deeply delithiated layered transition metal oxide, improves the stability of the MO bond, and then increases the oxygen release temperature of the positive electrode active material, thereby achieving a balance between the thermal safety performance, kinetic performance and high energy density of the battery cell.

[0041] In some embodiments, the layered transition metal oxide particles include a general formula of Li a M b O c components, wherein 0.8≤a<1, 0.8<b≤1, 1.5<c≤2, and M includes one or more of Ni, Co, Mn, and Al.

[0042] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte accounts for 1.5%-10%.

[0043] In the embodiment of the present application, when the mass proportion of the solid electrolyte is within the above range, the battery cell has good thermal safety performance, dynamic performance and high energy density.

[0044] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte accounts for 3%-7%.

[0045] In the embodiment of the present application, when the mass proportion of the solid electrolyte is within the above range, the battery cell has good thermal safety performance, dynamic performance and high energy density.

[0046] In some embodiments, the Dv50 of the positive electrode active material is 10 μm-15 μm.

[0047] In the embodiments of the present application, when the Dv50 of the positive electrode active material is within the above range, the dynamic performance of the battery cell can be further improved while ensuring the thermal safety performance.

[0048] In some embodiments, the primary sintering temperature is 600°C-1000°C.

[0049] In the embodiment of the present application, when the primary sintering temperature is within the above range, the battery cell has good thermal safety performance, good dynamic performance and high energy density.

[0050] In some embodiments, the primary sintering time is 2 hours to 8 hours.

[0051] In the embodiment of the present application, when the time for one sintering is within the above range, the battery cell has good thermal safety performance, good dynamic performance and high energy density.

[0052] The third aspect of the present application provides a method for preparing a positive electrode active material, comprising: heat treating a first mixture containing a layered transition metal oxide precursor to obtain a sintered product; mixing the sintered product with a solid electrolyte, performing a second heat treatment, and obtaining a positive electrode active material, wherein the solid electrolyte comprises one or more of lithium titanium aluminum phosphate oxide and lithium aluminum phosphate oxide.

[0053] In the embodiments of the present application, the positive electrode material prepared by the above method has good thermal safety performance, kinetic performance and high energy density. Although the mechanism is not clear, experiments show that this may be because a solid electrolyte is added and sintered together during the formation of the layered transition metal oxide, so that the solid electrolyte is doped inside the layered transition metal oxide particles, so that in the cross-section of the layered transition metal oxide particles, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particle, further improving the lithium replenishment effect of the solid electrolyte on the layered transition metal oxide particles, thereby improving the thermal safety performance of the high energy density positive electrode active material. In addition, the solid electrolyte used has a high ionic conductivity, which achieves a good balance between thermal safety performance, kinetic performance and high energy density.

[0054] In some embodiments, the general formula of the lithium aluminum titanium phosphate oxide is as shown in Formula II, Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 Formula II; the lithium aluminum phosphate oxide is Li3Al2(PO4)3.

[0055] The applicant's research has found that when the solid electrolyte is selected from the above range, it not only has good ionic conductivity, can improve the thermal safety and kinetic properties of the positive electrode active material, but also has a good lithium replenishment effect, that is, at high temperature, it replenishes lithium for the deeply delithiated layered transition metal oxide, improves the stability of the MO bond, and then increases the oxygen release temperature of the positive electrode active material, thereby achieving a balance between thermal safety performance, kinetic performance and high energy density.

[0056] In some embodiments, the layered transition metal oxide comprises a general formula of Li a M b O c components, wherein 0.8≤a<1, 0.8<b≤1, 1.5<c≤2, and M includes one or more of Ni, Co, Mn, and Al.

[0057] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte added before the second heat treatment accounts for 1.5%-10%.

[0058] In the embodiment of the present application, by adding a solid electrolyte before the second heat treatment, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0059] In some embodiments, the temperature of the heat treatment is 600°C-1000°C, the time of the heat treatment is 6h-10h, the temperature of the second heat treatment is 800°C-1000°C, and the time of the second heat treatment is 2h-8h.

[0060] In the embodiments of the present application, through the above-mentioned heat treatment conditions, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0061] In some embodiments, the first mixture also includes a solid electrolyte. Based on the mass of the positive electrode active material, the mass proportion of the solid electrolyte added to the first mixture is 0.1%-10%.

[0062] In the embodiment of the present application, by adding the solid electrolyte in the above mass proportion range into the first mixture, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0063] In some embodiments, the solid electrolyte includes one or more of lithium aluminum titanium phosphate oxide and lithium aluminum phosphate oxide, and the molar ratio of Li element to phosphorus element in the solid electrolyte added before the second heat treatment is greater than the molar ratio of Li element to phosphorus element in the solid electrolyte added before the heat treatment.

[0064] In the embodiments of the present application, since the degree of oxygen release inside the particles is relatively low, lithium aluminum titanium phosphate oxide with a lower Li content is doped at a position relatively closer to the interior of the particles, which can reduce the cost of the material while ensuring good thermal safety performance, kinetic performance and high energy density.

[0065] In some embodiments, the heat-treating the first mixture containing the layered transition metal oxide precursor to obtain the sintered product includes: performing a first heat treatment on the first mixture containing the layered transition metal oxide precursor, mixing the product with a solid electrolyte, and heat-treating it again to obtain the sintered product.

[0066] In the embodiments of the present application, through the above-mentioned heat treatment conditions, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0067] In some embodiments, the first mixture includes a solid electrolyte, and the molar ratio of Li element to P element in the solid electrolyte added before the second heat treatment is greater than the molar ratio of Li element to P element in the first mixture.

[0068] In the embodiments of the present application, since the degree of oxygen release inside the particles is relatively low, lithium aluminum titanium phosphate oxide with a lower Li content is doped at a position relatively closer to the interior of the particles, which can reduce the cost of the material while ensuring good thermal safety performance, kinetic performance and high energy density.

[0069] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte added before the second heat treatment accounts for 0.1%-10%.

[0070] In the embodiments of the present application, by adding a solid electrolyte having the above-mentioned mass proportion range before the second heat treatment, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0071] In some embodiments, the temperature of the first heat treatment is 700°C-900°C, and the temperature of the second heat treatment is 800°C-1000°C.

[0072] In the embodiments of the present application, through the above-mentioned heat treatment conditions, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0073] An embodiment of the fourth aspect of the present application provides a battery device, which includes a battery cell in any embodiment of the first aspect or a battery cell obtained by the preparation method in any embodiment of the second or third aspect, and the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

[0074] An embodiment of the fifth aspect of the present application provides an electrical device, which includes the battery device in any embodiment of the fourth aspect above, and the battery device is used to provide electrical energy.

[0075] An embodiment of the sixth aspect of the present application provides an energy storage device, which includes the battery device in any embodiment of the fourth aspect above, and the battery device is used to store electrical energy.

[0076] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0078] Figure 1 A schematic structural diagram of a vehicle according to some embodiments of the present application; Figure 2 Schematic diagram of the exploded structure of batteries according to some embodiments of the present application; Figure 3 This is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application; Figure 4 These are the DSC test results of Comparative Example 4, Example 1, Example 7, and Example 21 of this application; Description of reference numerals: Vehicles 1000; Battery device 100, controller 200, motor 300; Box body 10, first part 11, second part 12; Battery cell 20, end cover 21, electrode terminal 21a, housing 22, electrode assembly 23, and tab 23a. DETAILED DESCRIPTION

[0079] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0080] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0081] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0082] Mention of "embodiment" in this document means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this document generally indicates that the related objects before and after are in an "or" relationship.

[0083] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0084] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0085] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0086] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0087] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0088] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0089] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0090] As market demands for longer driving range in electric devices increase, higher energy density requirements are also being placed on battery cells. To meet these demands for long driving range and high efficiency, high-energy-density cathode materials are widely adopted. However, these materials often suffer from insufficient thermal safety performance under extreme operating conditions, such as high temperatures, which can easily lead to thermal runaway and pose safety risks. Therefore, achieving both improved energy density and thermal safety performance remains a critical challenge in current battery material technology.

[0091] The first embodiment of the present application provides a battery cell, wherein the battery cell includes a positive electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the surface of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes layered transition metal oxide particles, and the layered transition metal oxide particles include a general formula of Li a M b O c wherein 0.8≤a≤1.3, 0.8<b≤1, 1.5<c≤2, and M comprises one or more of Ni, Co, Mn, and Al; and in a cross section of the layered transition metal oxide particle, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particle.

[0092] In this paper, "Layered transition metal oxides Li a M b O c " is a class of inorganic compounds with a layered crystal structure, usually composed of alkali metal ions (such as lithium) embedded between transition metal oxide layers. Its basic structural unit is a two-dimensional layered framework formed by transition metals coordinated by oxygen octahedrons, and alkali metal ions can be reversibly embedded and extracted between the layers. This type of material is widely used in lithium-ion battery positive electrode materials due to its excellent ionic conductivity and high specific capacity.

[0093] In some embodiments, a is 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 or any range therebetween, b is 0.85, 0.90, 0.95, 1.0 or any range therebetween, and c is 1.6, 1.7, 1.8, 1.9, 2.0 or any range therebetween.

[0094] In some embodiments, Li a M b O c is LiCoO2, that is, a is 1, b is 1, and c is 2.

[0095] In some embodiments, Li a M b O c For lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide, such as LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.85 Co 0.1 Mn 0.05 O2、LiNi 0.9 Co 0.05 Mn 0.05 O2、LiNi 0.91 Co 0.05 Mn 0.04 O2、LiNi 0.95 Co 0.03 Mn 0.02 O2, etc.

[0096] As used herein, "near the surface of a cross-section of a layered metal oxide particle" refers to the molar ratio of Li to M within a region extending from the surface to the center of the particle, such as 0nm-30nm, 0-100nm, 0nm-200nm, 0nm-300nm, 0nm-400nm, or 0nm-500nm. "Near the center of the particle" refers to a region centered at the approximate center of the particle cross-section and having a radius of, for example, 30nm, 100nm, 200nm, 300nm, 400nm, 500nm, 1μm, 2μm, 3μm, 4μm, or 5μm, and for the same particle cross-section, the two regions do not overlap. The molar ratio of Li to M can be determined by conventional techniques in the art. For example, a battery cell is disassembled to obtain a positive electrode sheet, which is then cut using an ion beam to expose a cross-sectional area of ​​the positive electrode active material particle. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was then used to perform surface scanning (mapping) on ​​the particle cross section to obtain the element distribution and relative molar ratio of different regions.

[0097] To meet the demands of high battery life and high efficiency, high-energy-density cathode materials, such as layered transition metal oxides, are widely used. However, these materials often suffer from insufficient thermal safety performance under extreme operating conditions, such as high temperatures, which can easily lead to thermal runaway. Specifically, research has shown that at high temperatures (160°C-250°C), lithium ion release reduces the stability of the chemical bond (MO bond) between the M and O elements. Consequently, layered transition metal oxides in the lithium-ion-free state readily release oxygen. This released oxygen reacts with the electrolyte, the lithium in the negative electrode, and the negative electrode active material, generating a large amount of heat and causing thermal runaway.

[0098] The applicant's research found that by "the molar ratio of Li element to M element near the surface of the cross-section of the layered transition metal oxide particle is greater than the molar ratio of Li element to M element near the center of the particle", the battery cell can have high energy density and good thermal safety performance at the same time. Although the mechanism is not clear yet, experiments show that this may be related to the surface lithium replenishment of the layered transition metal oxide particles. The lithium ion release rate in the surface area of ​​the particle is faster, more lithium ions are released, and the oxygen release problem is more serious. Therefore, by increasing the molar ratio of Li element to M element in the surface area of ​​the particle, with the help of in-situ lithium replenishment of the surface area of ​​the particle that is deeply delithiated, the stability of the MO bond is improved, and then the oxygen release temperature of the positive electrode active material is increased, thereby improving the thermal safety performance of the high-capacity positive electrode active material, and achieving a balance between thermal safety performance and high energy density of the battery cell.

[0099] In some embodiments, a coating layer is further provided on the surface of the layered transition metal oxide particles, and the coating layer includes a solid electrolyte.

[0100] In some embodiments, the coating layer disposed on the surface of the layered transition metal oxide particles can intercept oxygen released from the layered transition metal oxide particles to a certain extent, further improving the thermal safety performance of the battery cell.

[0101] In some embodiments, the coating layer on the surface of the layered transition metal oxide particles can replenish lithium to the layered transition metal oxide particles under high temperature, thereby improving the thermal safety performance of the battery cell. However, lithium-replenishing materials often have poor ionic conductivity, sacrificing the battery's kinetic performance. The embodiments of the present application creatively discovered a solid electrolyte material that can replenish lithium. Using it as a coating layer for the layered transition metal oxide, it improves the thermal safety performance of the battery cell while also taking into account the battery's kinetic performance.

[0102] In some embodiments, the solid electrolyte includes one or more of lithium aluminum titanium phosphate oxide, lithium aluminum phosphate oxide, and tantalum-doped lithium lanthanum zirconium oxide.

[0103] In some embodiments, the general formula of the tantalum-doped lithium lanthanum zirconium oxide is as shown in Formula I, Li 6.4 La3Zr y1 Ta y2 O 12 , 0<y1<2 and 0<y2<2 Formula I.

[0104] In this paper, tantalum-doped lithium lanthanum zirconium oxide Li 6.4 La3Zr y1 Ta y2 O 12, is a type of garnet-type solid electrolyte that optimizes the crystal structure and ion conductivity by partially replacing zirconium with tantalum. It can be understood that, ideally, the sum of y1 and y2 is 2.

[0105] In some embodiments, y1 is 0.2, 0.5, 0.8, 1.1, 1.4, 1.7, or any range therebetween.

[0106] In some embodiments, y2 is 1.8, 1.5, 1.2, 0.9, 0.6, 0.3, or any range therebetween.

[0107] In some embodiments, the general formula of the lithium aluminum titanium phosphate oxide is as shown in Formula II, Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 Formula II; the lithium aluminum phosphate oxide is Li3Al2(PO4)3.

[0108] In this paper, lithium aluminum titanate phosphate oxide Li x1 Al x2 Ti x3 (PO4)3 is a NASICON-type solid electrolyte. It can be understood that under ideal conditions, x2=x1-1 and x3=2-x2.

[0109] In some embodiments, x1 is 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, or any range therebetween.

[0110] In some embodiments, x2 is 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, or any range therebetween.

[0111] In some embodiments, x3 is 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.7, or any range therebetween.

[0112] The applicant's research has found that when the solid electrolyte is selected from the above range, it not only has good ionic conductivity, which can improve the thermal safety performance of the battery cell while taking into account the kinetic performance, but also has a good lithium replenishment effect, that is, it can replenish lithium for deeply delithiated layered transition metal oxides at high temperatures, improve the stability of the MO bond, and then increase the oxygen release temperature of the positive electrode active material, thereby achieving a balance between the thermal safety performance, kinetic performance and high energy density of the battery cell.

[0113] In some embodiments, the coating layer has a thickness of 0.02 μm to 2 μm.

[0114] In some embodiments, the thickness of the coating layer is 0.02 μm, 0.09 μm, 0.16 μm, 0.23 μm, 0.30 μm, 0.37 μm, 0.44 μm, 0.51 μm, 0.58 μm, 0.65 μm, 0.72 μm, 0.79 μm, 0.86 μm, 0.93 μm, 1.00 μm, 1.07 μm, 1.14 μm, 1.21 μm, 1.28 μm, 1.35 μm, 1.42 μm, 1.49 μm, 1.56 μm, 1.63 μm, 1.70 μm, 1.77 μm, 1.84 μm, 1.91 μm, 1.98 μm, 2.00 μm, or any range therebetween.

[0115] In the embodiment of the present application, when the thickness of the coating layer is within the above range, the thermal safety performance of the battery cell can be further improved.

[0116] In some embodiments, the layered transition metal oxide particles are doped with La, Zr, and Ta.

[0117] Herein, as an example, the doping of the above elements can be achieved by doping tantalum-doped lithium lanthanum zirconium oxide as shown in Formula I into the layered transition metal oxide particles.

[0118] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by doping the above elements.

[0119] In some embodiments, in a cross section of the layered transition metal oxide particle, the mass contents of La, Zr, and Ta near the surface are respectively greater than the mass contents of La, Zr, and Ta near the center.

[0120] Herein, as an example, tantalum-doped lithium lanthanum zirconium oxide as shown in Formula I can be allowed to diffuse from the surface of the layered transition metal oxide particles into the interior of the particles through solid phase diffusion, so that in the cross-section of the layered transition metal oxide particles, the mass contents of the La element, the Zr element, and the Ta element near the surface are greater than the mass contents of the La element, the Zr element, and the Ta element near the center, respectively.

[0121] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0122] In some embodiments, the layered transition metal oxide particles are doped with Al, Ti, and P, and M includes one or more of Ni, Co, and Mn.

[0123] Herein, as an example, the doping of the above elements can be achieved by doping lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide as shown in Formula II into the layered transition metal oxide.

[0124] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by doping the above elements.

[0125] In some embodiments, in a cross section of the layered transition metal oxide particle, the mass contents of Al, Ti, and P near the surface are respectively greater than the mass contents of Al, Ti, and P near the center.

[0126] Herein, as an example, lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide as shown in Formula II can be allowed to enter the interior of the particle from the surface of the layered transition metal oxide particle by solid-phase diffusion, so that in the cross-section of the layered transition metal oxide particle, the mass content of the Al element, the Ti element and the P element near the surface is greater than the mass content of the Al element, the Ti element and the P element near the center, respectively.

[0127] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0128] In some embodiments, the layered transition metal oxide particles are doped with Al, Ti, and P, wherein in a cross section of the layered transition metal oxide particles, the molar ratio of Li to P near the surface is greater than the molar ratio of Li to P near the center.

[0129] Herein, as an example, lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide as shown in Formula II can be allowed to enter the interior of the particle from the surface of the layered transition metal oxide particle by solid-phase diffusion, so that in the cross-section of the layered transition metal oxide particle, the molar ratio of the Li element to the P element near the surface is greater than the molar ratio of the Li element to the P element near the center.

[0130] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0131] In some embodiments, the layered transition metal oxide particles are doped with Al, Ti, and P, and M includes one or more of Ni, Co, and Mn, wherein in a cross section of the layered transition metal oxide particles, the molar ratio of Al to Ti near the surface is greater than the molar ratio of Al to Ti near the center.

[0132] Herein, as an example, lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide as shown in Formula II can be allowed to enter the interior of the particle from the surface of the layered transition metal oxide particle by solid-phase diffusion, so that in the cross-section of the layered transition metal oxide particle, the molar ratio of the Al element to the Ti element near the surface is greater than the molar ratio of the Al element to the Ti element near the center.

[0133] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0134] In some embodiments, in a cross section of the layered transition metal oxide particle, in an outer region of 1 μm-3 μm from the surface toward the geometric center, the molar ratio of Al element, Ti element, and P element is (1-2):(0-1):3:3.

[0135] In this article, the term "geometric center" refers to the point at which the mass or volume distribution of a particle in all directions in three-dimensional space is symmetrical, and can usually be approximated as the particle's centroid. For ideal spherical particles, the geometric center is the center of the sphere. This term is used as a reference point to describe the internal structure or composition distribution of a particle.

[0136] In this article, as an example, the above-mentioned element distribution can be achieved by doping lithium titanium aluminum phosphate oxide or lithium aluminum phosphate oxide with corresponding element ratios in the process of forming corresponding regions of layered transition metal oxide particles. The higher the lithium content in lithium titanium aluminum phosphate oxide or lithium aluminum phosphate oxide, the better the lithium replenishment effect.

[0137] In some embodiments, in a cross section of the layered transition metal oxide particle, in an outer region of 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3.0 μm, or any numerical range therebetween, or any numerical range therebetween, from the surface toward the geometric center, the molar ratio of the Al element, the Ti element, and the P element is 1.00:0.0:3, 1.00:0.2:3, 1.00:0.4:3, 1.00:0.6:3, 1.00:0.8:3, 1.00:1.0:3, 1.25:0.0:3, 1.25:0.2:3, 1.25:0.4:3, 1.25:0.6:3, 1.25:0.8:3, 1.25:1.0:3, 1.50:0.0:3, 1.50:0.2:3, 1.50:0.4:3, 1.50:0.6:3, 1.50:0.8:3, 1.50:1.0:3, 1.75:0.0:3, 1.75:0.2:3, 1.75:0.4:3, 1.75:0.6:3, 1.75:0.8:3, 1.75:1.0:3, 2.00:0.0:3, 2.00:0.2:3, 2.00:0.4:3, 2.00:0.6:3, 2.00:0.8:3, 2.00:1.0:3.

[0138] In the embodiments of the present application, the thermal safety performance and dynamic performance of the battery cell are further improved by the element distribution within the above range.

[0139] In some embodiments, in a cross section of the layered transition metal oxide particle, in a core region with a diameter of 3 μm-10 μm and a circle centered at the geometric center, the molar ratio of Al element, Ti element, and P element is (0.2-1):(1-1.8):3.

[0140] Herein, as an example, the above-mentioned element distribution may be achieved by doping lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide having corresponding element ratios during the process of forming corresponding regions of the layered transition metal oxide particles.

[0141] In some embodiments, in a cross section of the layered transition metal oxide particle, in a core region with a diameter of 3.0 μm, 4.0 μm, 5.0 μm, 6.0 μm, 7.0 μm, 8.0 μm, 9.0 μm, 10.0 μm, or any range therebetween, with the geometric center as the center, the molar ratio of the Al element, the Ti element, and the P element is 0.2:1.0:3, 0.3:1.2:3, 0.4:1.3:3, 0.5:1.4:3, 0.6:1.5:3, 0.7:1.6:3, 0.8:1.7:3, 0.9:1.8:3, 1.0:1.8:3, or any range therebetween.

[0142] In the embodiments of the present application, the distribution of elements within the above range further improves the thermal safety and dynamic performance of the battery cells. Furthermore, since the core region has a relatively low degree of oxygen release, there is no need for doping with high-lithium-content lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide, thereby reducing production costs.

[0143] In some embodiments, in the cross-section of the layered transition metal oxide particles, in a core region with a diameter of 3 μm-7 μm with the geometric center as the center, the molar ratio of Al element, Ti element and P element is (0.2-0.8):(1.2-1.8):3; in an outer region of 1 μm-3 μm from the surface to the geometric center, the molar ratio of Al element, Ti element and P element is (1.2-2):(0-0.8):3; the thickness of the middle region between the core region and the outer region is 1 μm-3 μm, and in the middle region, the molar ratio of Al element, Ti element and P element is (0.8-1.2):(0.8-1.2):3.

[0144] Herein, as an example, the above-mentioned element distribution may be achieved by doping lithium aluminum titanium phosphate oxide or lithium aluminum phosphate oxide having corresponding element ratios during the process of forming corresponding regions of the layered transition metal oxide particles.

[0145] In some embodiments, in a cross section of the layered transition metal oxide particles containing lithium, in a core region with a diameter of 3.0 μm, 4.0 μm, 5.0 μm, 6.0 μm, 7.0 μm, or any range therebetween, with the geometric center as the center, the molar ratio of the Al element, the Ti element, and the P element may be 0.2:1.2:3, 0.3:1.3:3, 0.4:1.4:3, 0.5:1.5:3, 0.6:1.6:3, 0.7:1.7:3, 0.8:1.8:3, or any range therebetween; in an outer region from the surface to 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, or any range therebetween, the Al element The molar ratio of Al element, Ti element and P element may be 1.2:0.0:3, 1.3:0.2:3, 1.4:0.3:3, 1.5:0.4:3, 1.6:0.5:3, 1.7:0.6:3, 1.8:0.7:3, 2.0:0.8:3 or any numerical range therebetween; the thickness of the intermediate region between the core region and the outer region is 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm or any numerical range therebetween, and in the intermediate region, the molar ratio of Al element, Ti element and P element may be 0.8:0.8:3, 0.9:0.9:3, 1.0:1.0:3, 1.1:1.1:3, 1.2:1.2:3 or any numerical range therebetween.

[0146] In the embodiments of the present application, the distribution of elements within the above range further improves the thermal safety and dynamic performance of the battery cells. Furthermore, since the core and intermediate regions have relatively low oxygen release, there is no need for doping with lithium-rich lithium aluminum titanium phosphate or lithium aluminum phosphate, thereby reducing production costs.

[0147] In some embodiments, the Dv50 of the positive electrode active material is 10 μm-15 μm.

[0148] In this article, the term "volume average particle size Dv50" has a well-known meaning in the art, which respectively represents the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50%. The volume distribution particle size Dv50 of the positive electrode active material can be tested using instruments and methods known in the art. For example, it can be conveniently measured using a laser particle size analyzer with reference to GB / T 19077-2016 particle size distribution laser diffraction method. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd. in the UK. The positive electrode active material can be freshly prepared or obtained by scraping powder from the positive electrode film layer after disassembling the battery cell. For example, disassemble the battery to take the positive electrode sheet, scrape the positive electrode film powder as the sample to be tested, and then measure the sample according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0149] In some embodiments, the Dv50 of the positive active material is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, or 15 μm.

[0150] In the embodiments of the present application, when the Dv50 of the positive electrode active material is within the above range, the dynamic performance of the battery cell can be further improved while ensuring the thermal safety performance.

[0151] An embodiment of the second aspect of the present application provides a method for preparing a positive electrode active material, comprising: coating layered transition metal oxide particles with a solid electrolyte to obtain a coated product; sintering the coated product once to obtain a positive electrode active material; the solid electrolyte comprises one or more of lithium aluminum titanium phosphate oxide, lithium aluminum phosphate oxide, and tantalum-doped lithium lanthanum zirconium oxide.

[0152] In the embodiments of the present application, the positive electrode material prepared by the above method has good thermal safety performance, kinetic performance and high energy density. Although the mechanism is not clear yet, experiments show that this may be because the first sintering not only makes the coating layer stably coated on the surface of the particles, but also replenishes lithium on the surface of the particles, so that in the cross section of the layered transition metal oxide particles, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particle; in some cases, the solid electrolyte can also diffuse into the interior of the particles through the solid phase, further improving the lithium replenishment effect of the solid electrolyte on the layered transition metal oxide particles, thereby improving the thermal safety performance of the high energy density positive electrode active material. In addition, the solid electrolyte used has a high ionic conductivity, which achieves a good balance between thermal safety performance, kinetic performance and high energy density.

[0153] In some embodiments, the general formula of the tantalum-doped lithium lanthanum zirconium oxide is as shown in Formula I, Li 6.4 La3Zr y1 Ta y2 O 12 , 0<y1<2 and 0<y2<2 Formula I.

[0154] In this paper, tantalum-doped lithium lanthanum zirconium oxide Li 6.4 La3Zr y1 Ta y2 O 12 , is a type of garnet-type solid electrolyte that optimizes the crystal structure and ion conductivity by partially replacing zirconium with tantalum. It can be understood that, ideally, the sum of y1 and y2 is 2.

[0155] In some embodiments, y1 is 0.2, 0.5, 0.8, 1.1, 1.4, 1.7, or any range therebetween.

[0156] In some embodiments, y2 is 1.8, 1.5, 1.2, 0.9, 0.6, 0.3, or any range therebetween.

[0157] In some embodiments, the general formula of the lithium aluminum titanium phosphate oxide is as shown in Formula II, Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 Formula II; the lithium aluminum phosphate oxide is Li3Al2(PO4)3.

[0158] In this paper, lithium aluminum titanate phosphate oxide Li x1 Al x2 Ti x3 (PO4)3 is a NASICON-type solid electrolyte. It can be understood that under ideal conditions, x2 = x1-1 and x3 = 2-x2.

[0159] In some embodiments, x1 is 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, or any range therebetween.

[0160] In some embodiments, x2 is 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, or any range therebetween.

[0161] In some embodiments, x3 is 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.7, or any range therebetween.

[0162] The applicant's research has found that when the solid electrolyte is selected from the above range, it not only has good ionic conductivity, which can improve the thermal safety performance of the battery cell while taking into account the kinetic performance, but also has a good lithium replenishment effect, that is, at high temperature, it replenishes lithium for the deeply delithiated layered transition metal oxide, improves the stability of the MO bond, and then increases the oxygen release temperature of the positive electrode active material, thereby achieving a balance between the thermal safety performance, kinetic performance and high energy density of the battery cell.

[0163] In some embodiments, the layered transition metal oxide particles include a general formula of Li a M b O c components, wherein 0.8≤a<1, 0.8<b≤1, 1.5<c≤2, and M includes one or more of Ni, Co, Mn, and Al.

[0164] In this paper, "Layered transition metal oxides Li a M b O c " is a class of inorganic compounds with a layered crystal structure, usually composed of alkali metal ions (such as lithium) embedded between transition metal oxide layers. Its basic structural unit is a two-dimensional layered framework formed by transition metals coordinated by oxygen octahedrons, and alkali metal ions can be reversibly embedded and extracted between the layers. This type of material is widely used in lithium-ion battery positive electrode materials due to its excellent ionic conductivity and high specific capacity.

[0165] In some embodiments, a is 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 or any range therebetween, b is 0.85, 0.90, 0.95, 1.0 or any range therebetween, and c is 1.6, 1.7, 1.8, 1.9, 2.0 or any range therebetween.

[0166] In some embodiments, Li a M b O c is LiCoO2, that is, a is 1, b is 1, and c is 2.

[0167] In some embodiments, Li a M b O c For lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide, such as LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.85 Co 0.1 Mn 0.05 O2、LiNi 0.9 Co 0.05 Mn 0.05 O2、LiNi0.91 Co 0.05 Mn 0.04 O2、LiNi 0.95 Co 0.03 Mn 0.02 O2, etc.

[0168] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte accounts for 1.5%-10%.

[0169] In some embodiments, based on the mass of the positive electrode active material, the mass proportion of the solid electrolyte can be 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0% or any numerical range therebetween.

[0170] In the embodiment of the present application, when the mass proportion of the solid electrolyte is within the above range, the battery cell has good thermal safety performance, dynamic performance and high energy density.

[0171] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte accounts for 3%-7%.

[0172] In the embodiment of the present application, when the mass proportion of the solid electrolyte is within the above range, the battery cell has good thermal safety performance, dynamic performance and high energy density.

[0173] In some embodiments, the Dv50 of the positive electrode active material is 10 μm-15 μm.

[0174] In this article, the term "volume average particle size Dv50" has a well-known meaning in the art, which respectively represents the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50%. The volume distribution particle size Dv50 of the positive electrode active material can be tested using instruments and methods known in the art. For example, it can be conveniently measured using a laser particle size analyzer with reference to GB / T 19077-2016 particle size distribution laser diffraction method. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd. in the UK. The positive electrode active material can be freshly prepared or obtained by scraping powder from the positive electrode film layer after disassembling the battery cell. For example, disassemble the battery, take the positive electrode sheet, scrape the positive electrode film powder as the sample to be tested, and then measure the sample according to the GB / T19077-2016 / ISO 13320:2009 standard.

[0175] In some embodiments, the Dv50 of the positive active material is 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, or 15 μm.

[0176] In the embodiments of the present application, when the Dv50 of the positive electrode active material is within the above range, the dynamic performance of the battery cell can be further improved while ensuring the thermal safety performance.

[0177] In some embodiments, the primary sintering temperature is 600°C-1000°C.

[0178] In some embodiments, the primary sintering temperature is 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, or any range therebetween.

[0179] In the embodiment of the present application, when the primary sintering temperature is within the above range, the battery cell has good thermal safety performance, good dynamic performance and high energy density.

[0180] In some embodiments, a solid electrolyte is used to coat layered transition metal oxide particles to obtain a coated product; the coated product is sintered once to obtain a positive electrode active material, wherein the solid electrolyte is Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8, or Li3Al2(PO4)3, wherein the primary sintering is within the range of 600℃-1000℃ to prepare the positive electrode active material, and the solid electrolyte can replenish lithium to the layered transition metal oxide particles under high temperature.

[0181] In some embodiments, a solid electrolyte is used to coat layered transition metal oxide particles to obtain a coated product; the coated product is sintered once to obtain a positive electrode active material, wherein the solid electrolyte is Li 6.4 La3Zr y1 Ta y2 O 12 , 0<y1<2 and 0<y2<2, wherein the primary sintering is in the range of 800℃-1000℃, and the positive electrode active material is prepared, and the solid electrolyte can replenish lithium for the layered transition metal oxide particles under high temperature.

[0182] In some embodiments, the primary sintering time is 2 hours to 8 hours.

[0183] In some embodiments, the primary sintering time is 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, or any range therebetween.

[0184] In the embodiment of the present application, when the time for one sintering is within the above range, the battery cell has good thermal safety performance, good dynamic performance and high energy density.

[0185] The third aspect of the present application provides a method for preparing a positive electrode active material, comprising: heat treating a first mixture containing a layered transition metal oxide precursor to obtain a sintered product; mixing the sintered product with a solid electrolyte, performing a second heat treatment, and obtaining a positive electrode active material, wherein the solid electrolyte comprises one or more of lithium titanium aluminum phosphate oxide and lithium aluminum phosphate oxide.

[0186] In the embodiments of the present application, the positive electrode material prepared by the above method has good thermal safety performance, kinetic performance and high energy density. Although the mechanism is not clear, experiments show that this may be because a solid electrolyte is added and sintered together during the formation of the layered transition metal oxide, so that the solid electrolyte is doped inside the layered transition metal oxide particles, so that in the cross-section of the layered transition metal oxide particles, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particle, further improving the lithium replenishment effect of the solid electrolyte on the layered transition metal oxide particles, thereby improving the thermal safety performance of the high energy density positive electrode active material. In addition, the solid electrolyte used has a high ionic conductivity, which achieves a good balance between thermal safety performance, kinetic performance and high energy density.

[0187] In some embodiments, the general formula of the lithium aluminum titanium phosphate oxide is as shown in Formula II, Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 Formula II; the lithium aluminum phosphate oxide is Li3Al2(PO4)3.

[0188] In some embodiments, x1 is 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, or any range therebetween.

[0189] In some embodiments, x2 is 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, or any range therebetween.

[0190] In some embodiments, x3 is 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.7, or any range therebetween.

[0191] The applicant's research has found that when the solid electrolyte is selected from the above range, it not only has good ionic conductivity, can improve the thermal safety and kinetic properties of the positive electrode active material, but also has a good lithium replenishment effect, that is, at high temperature, it replenishes lithium for the deeply delithiated layered transition metal oxide, improves the stability of the MO bond, and then increases the oxygen release temperature of the positive electrode active material, thereby achieving a balance between thermal safety performance, kinetic performance and high energy density.

[0192] In some embodiments, the layered transition metal oxide comprises a general formula of Li a M b O c components, wherein 0.8≤a<1, 0.8<b≤1, 1.5<c≤2, and M includes one or more of Ni, Co, Mn, and Al.

[0193] In this paper, "Layered transition metal oxides Li a M b O c " is a class of inorganic compounds with a layered crystal structure, usually composed of alkali metal ions (such as lithium) embedded between transition metal oxide layers. Its basic structural unit is a two-dimensional layered framework formed by transition metals coordinated by oxygen octahedrons, and alkali metal ions can be reversibly embedded and extracted between the layers. This type of material is widely used in lithium-ion battery positive electrode materials due to its excellent ionic conductivity and high specific capacity.

[0194] In some embodiments, a is 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 or any range therebetween, b is 0.85, 0.90, 0.95, 1.0 or any range therebetween, and c is 1.6, 1.7, 1.8, 1.9, 2.0 or any range therebetween.

[0195] In some embodiments, Li a M b O c is LiCoO2, that is, a is 1, b is 1, and c is 2.

[0196] In some embodiments, Li a M b O c For lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide, such as LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.85 Co 0.1 Mn0.05 O2、LiNi 0.9 Co 0.05 Mn 0.05 O2、LiNi 0.91 Co 0.05 Mn 0.04 O2、LiNi 0.95 Co 0.03 Mn 0.02 O2, etc.

[0197] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte added before the second heat treatment accounts for 1.5%-10%.

[0198] Herein, it can be understood that the solid electrolyte introduced before the second heat treatment is doped inside the positive electrode active material through the second heat treatment.

[0199] In some embodiments, based on the mass of the positive electrode active material, the mass proportion of the solid electrolyte added before the second heat treatment can be 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0% or any numerical range therebetween.

[0200] In the embodiment of the present application, by adding a solid electrolyte before the second heat treatment, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0201] In some embodiments, the temperature of the heat treatment is 600°C-1000°C, the time of the heat treatment is 6h-10h, the temperature of the second heat treatment is 800°C-1000°C, and the time of the second heat treatment is 2h-8h.

[0202] In some embodiments, the temperature of the heat treatment is 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C or any numerical range therebetween, the time of the heat treatment is 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h or any numerical range therebetween, the temperature of the second heat treatment is 800°C, 825°C, 850°C, 875°C, 900°C, 925°C, 950°C, 975°C, 1000°C or any numerical range therebetween, and the time of the second heat treatment is 2h, 3h, 4h, 5h, 6h, 7h, 8h or any numerical range therebetween.

[0203] In the embodiments of the present application, through the above-mentioned heat treatment conditions, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0204] In some embodiments, the first mixture also includes a solid electrolyte. Based on the mass of the positive electrode active material, the mass proportion of the solid electrolyte added to the first mixture is 0.1%-10%.

[0205] In this context, it can be understood that since the particles of the positive electrode active material gradually increase in size, the earlier the solid electrolyte is added, the closer the electrolyte is doped into the particles to the center of the particles. In other words, the solid electrolyte added in the first mixture is doped into the particles closer to the center of the particles than the solid electrolyte added before the second sintering step.

[0206] In some embodiments, the first mixture also includes a solid electrolyte. Based on the mass of the positive electrode active material, the mass proportion of the solid electrolyte added to the first mixture is 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0% or any numerical range therebetween.

[0207] In the embodiment of the present application, by adding the solid electrolyte in the above mass proportion range into the first mixture, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0208] In some embodiments, the solid electrolyte includes one or more of lithium aluminum titanium phosphate oxide and lithium aluminum phosphate oxide, and the molar ratio of Li element to phosphorus element in the solid electrolyte added before the second heat treatment is greater than the molar ratio of Li element to phosphorus element in the solid electrolyte added before the heat treatment.

[0209] In this context, it can be understood that since the particles of the positive electrode active material gradually increase in size, the earlier the solid electrolyte is added, the closer the electrolyte is doped into the particles to the center of the particles. In other words, the solid electrolyte added before heat treatment is doped into the particles closer to the center of the particles than the solid electrolyte added before the second sintering step.

[0210] In the embodiments of the present application, since the degree of oxygen release inside the particles is relatively low, lithium aluminum titanium phosphate oxide with a lower Li content is doped at a position relatively closer to the interior of the particles, which can reduce the cost of the material while ensuring good thermal safety performance, kinetic performance and high energy density.

[0211] In some embodiments, heat treating the first mixture containing the layered transition metal oxide precursor to obtain a sintered product includes: performing a first heat treatment on the first mixture containing the layered transition metal oxide precursor, mixing the product with a solid electrolyte, and heat treating it again to obtain a sintered product.

[0212] In the embodiments of the present application, through the above-mentioned heat treatment conditions, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0213] In some embodiments, the first mixture includes a solid electrolyte, and the molar ratio of Li element to P element in the solid electrolyte added before the second heat treatment is greater than the molar ratio of Li element to P element in the first mixture.

[0214] In this context, it can be understood that since the particles of the positive electrode active material gradually increase in size, the earlier the solid electrolyte is added, the closer the position of the added electrolyte doped in the particles is to the center of the particles.

[0215] In the embodiments of the present application, since the degree of oxygen release inside the particles is relatively low, lithium aluminum titanium phosphate oxide with a lower Li content is doped at a position relatively closer to the interior of the particles, which can reduce the cost of the material while ensuring good thermal safety performance, kinetic performance and high energy density.

[0216] In some embodiments, based on the mass of the positive electrode active material, the mass of the solid electrolyte added before the second heat treatment accounts for 0.1%-10%.

[0217] In some embodiments, based on the mass of the positive electrode active material, the mass proportion of the solid electrolyte added before the re-heat treatment is 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0% or any numerical range therebetween.

[0218] In the embodiments of the present application, by adding a solid electrolyte having the above-mentioned mass proportion range before the second heat treatment, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0219] In some embodiments, the temperature of the first heat treatment is 700°C-900°C, and the temperature of the second heat treatment is 800°C-1000°C.

[0220] In some embodiments, the temperature of the first heat treatment is 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, 820°C, 840°C, 860°C, 880°C, 900°C or any range therebetween, and the temperature of the second heat treatment is 800°C, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C or any range therebetween.

[0221] In the embodiments of the present application, through the above-mentioned heat treatment conditions, the prepared positive electrode active material has good thermal safety performance, kinetic performance and high energy density.

[0222] An embodiment of the fourth aspect of the present application provides a battery device, which includes a battery cell in any embodiment of the first aspect or a battery cell obtained by the preparation method in any embodiment of the second or third aspect, and the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

[0223] An embodiment of the fifth aspect of the present application provides an electrical device, which includes the battery device in any embodiment of the fourth aspect above, and the battery device is used to provide electrical energy.

[0224] An embodiment of the sixth aspect of the present application provides an energy storage device, which includes the battery device in any embodiment of the fourth aspect above, and the battery device is used to store electrical energy.

[0225] Typically, a battery cell consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0226] [Positive electrode] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.

[0227] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0228] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0229] In some embodiments, the positive electrode film layer may further optionally include a binder. For example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0230] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0231] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0232] [Negative electrode] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0233] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0234] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0235] In some embodiments, the negative electrode active material may adopt the negative electrode active material for battery cells that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0236] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0237] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0238] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0239] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0240] [Electrolytes] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0241] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0242] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0243] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0244] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0245] [Isolation film] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0246] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0247] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical devices or energy storage devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and battery devices disclosed in this application can be used to alleviate lithium plating at the negative electrode of high-energy-density batteries, thereby improving battery performance stability and battery life.

[0248] The present invention provides an electrical device that uses a battery device as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0249] An embodiment of the present application also provides an energy storage device that uses a battery device as a power source. The energy storage device may be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0250] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0251] Please refer to Figure 1 , Figure 1 Schematic diagram of the structure of the vehicle provided for some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 100 is provided inside the vehicle 1000, and the battery device 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000. For example, the battery device 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0252] In some embodiments of the present application, the battery device 100 can serve not only as an operating power source for the vehicle 1000 , but also as a driving power source for the vehicle 1000 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000 .

[0253] Please refer to Figure 2 , Figure 2This is a schematic diagram of the exploded structure of a battery device provided in some embodiments of the present application. The battery device 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 is used to provide a storage space for the battery cell 20, and the housing 10 can have a variety of structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open, and the first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. The first portion 11 and the second portion 12 can also be hollow structures with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have a variety of shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0254] In the battery device 100, there may be multiple battery cells 20, which may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery unit 20 may be housed within the housing 10. Alternatively, the battery device 100 may comprise multiple battery cells 20 connected in series, in parallel, or in a hybrid connection to form a battery module, which is then further connected in series, in parallel, or in a hybrid connection to form a single unit and housed within the housing 10. The battery device 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0255] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0256] Please refer to Figure 3 , Figure 3 The following is a schematic diagram of the decomposition structure of a battery cell provided in some embodiments of the present application. A battery cell 20 is the smallest unit that constitutes a battery device. Figure 3 The battery cell 20 includes an end cap 21, a shell 22, an electrode assembly 23 and other functional components.

[0257] The end cap 21 is a component that fits over the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain degree of hardness and strength (such as an aluminum alloy). This prevents deformation of the end cap 21 during compression and collision, providing the battery cell 20 with greater structural strength and improved safety. The end cap 21 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the electrode assembly 23 for inputting or outputting electrical energy from the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism to release internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0258] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylinder, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic.

[0259] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 23a. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs 23a connect the electrode terminals to form a current loop.

[0260] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0261] 1. Preparation Example 1. Preparation of lithium aluminum titanium phosphate / lithium aluminum phosphate (LATP) In an argon-protected glove box, Li 1.2 Al 0.2 Ti 1.8 (PO4)3 is mixed with a certain amount of lithium metal powder, and the mixture is heated at 300℃ on a heating table to prepare Li 1.5 Al 0.5 Ti 1.5 (PO4)3、Li2AlTi(PO4)3、Li 2.5 Al 1.5 Ti 0.5 (PO4)3, Li3Al2(PO4)3, the specific reaction conditions are as follows: Control the Li content in the mixture 1.2 Al 0.2 Ti 1.8 The molar ratio of (PO4)3 to lithium metal was 1:0.4, and the reaction was maintained at 300 °C for 40 min under an argon atmosphere to obtain Li 1.5 Al 0.5 Ti 1.5 (PO4)3; Control the Li content in the mixture 1.2 Al 0.2 Ti 1.8 The molar ratio of (PO4)3 to lithium metal was 1:1, and Li2AlTi(PO4)3 was prepared by maintaining the reaction at 300 °C for 70 min under argon atmosphere; Control the Li content in the mixture 1.2 Al 0.2 Ti 1.8 The molar ratio of (PO4)3 to lithium metal was 1:1.8, and the reaction was maintained at 300 °C for 110 min under an argon atmosphere to obtain Li 2.5 Al 1.5 Ti 0.5 (PO4)3; Control the Li content in the mixture 1.2 Al 0.2 Ti 1.8The molar ratio of (PO4)3 to lithium metal was 1:2.4, and Li3Al2(PO4)3 was prepared by maintaining the reaction at 300°C for 150 min under argon atmosphere.

[0262] 2. Preparation of positive electrode active materials 2.1 Preparation of Comparative Examples 1-3 and Preparation Examples 1-19 N-methylpyrrolidone (NMP) was used as solvent, and NMP was mixed with solid electrolyte to prepare solid electrolyte sol with a mass concentration of 50%-70%. The obtained sol was mixed with ternary material (LiNi 0.9 Co 0.05 Mn 0.05 O2) are fully mixed and then sintered once to obtain a positive electrode active material. The specific parameters are shown in Table 1 below.

[0263] Table 1

[0264] 2.2 Preparation Examples 20-22 2.21 Preparation Example 20 Inner layer: ternary material (LiNi 0.9 Co 0.05 Mn 0.05 O2) precursor and Li 1.5 Al 0.5 Ti 1.5 (PO4)3 (based on the mass of the positive electrode active material, accounting for 1.33% by mass) is mixed and subjected to a first heat treatment (900°C, 8h) to obtain a first product; Middle layer: The first product is mixed with Li2AlTi(PO4)3 (based on the mass of the positive electrode active material, accounting for 1.33% by mass) and subjected to a second heat treatment (900℃, 5h) to obtain the second product; Outer layer: the second product and Li 2.5 Al 1.5 Ti 0.5 (PO4)3 (based on the mass of the positive electrode active material, the mass accounts for 1.33%) and is mixed, and a third heat treatment (900°C, 5h) is performed to obtain a positive electrode active material.

[0265] 2.22 Preparation Example 21 Inner layer: ternary material (LiNi 0.9 Co 0.05 Mn 0.05 O2) precursor and Li 1.5 Al 0.5 Ti 1.5 (PO4)3 (based on the mass of the positive electrode active material, accounting for 2.5% by mass) is mixed and subjected to a first heat treatment (900°C, 8h) to obtain a first product; Outer layer: The first product was mixed with Li2AlTi(PO4)3 (2.5% by mass based on the mass of the positive electrode active material) and subjected to a second heat treatment (900°C, 5h) to obtain the positive electrode active material.

[0266] 2.23 Preparation Example 22 Inner layer: for ternary materials (LiNi 0.9 Co 0.05 Mn 0.05 O2) is subjected to a first heat treatment (900°C, 8h) to obtain a sintered product; Outer layer: sintered product and Li 2.5 Al 1.5 Ti 0.5 (PO4)3 (based on the mass of the positive electrode active material, accounting for 5% by mass) was mixed and subjected to a second heat treatment (900°C, 5h) to obtain the positive electrode active material.

[0267] 2. Example Example 1 (1) Preparation of positive electrode Cathode slurry preparation: The positive electrode active material prepared in Preparation Example 1, conductive agent CNT, conductive agent SP, binder PVDF, surfactant (polyvinyl pyrrolidone), and solvent NMP were uniformly mixed in a weight ratio of 98.04:0.5:0.5:0.9:0.06:80, coated on both sides of aluminum foil, and cold pressed and cut to obtain a positive electrode sheet.

[0268] (2) Preparation of negative electrode sheet Silicon-carbon material, conductive carbon black, conductive agent CNT, binder SBR, carboxymethyl cellulose (CMC), and solvent deionized water are uniformly mixed in a weight ratio of 79.83:9.67:0.5:8.8:1.2:50, coated on both sides of the copper foil, and then cold pressed and cut to obtain the negative electrode sheet.

[0269] (3) Isolation film A polyethylene film with a thickness of 13 μm was used as the separator.

[0270] (4) Preparation of electrolyte In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), lithium salt lithium hexafluorophosphate LiPF6 was dissolved in organic solvents ethylene carbonate, diethyl carbonate, and dimethyl carbonate (volume ratio of 1:1:1) and stirred evenly to obtain an electrolyte with a LiPF6 concentration of 1 mol / L.

[0271] (5) Preparation of battery cells The positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is placed between the positive and negative electrode sheets to play an isolating role. Then they are wound to obtain a battery cell, the tabs are welded to the battery cell, and the battery cell is placed in an aluminum shell. The electrolyte is then injected and sealed. After standing, cold pressing, formation, shaping, capacity testing and other processes, a lithium-ion secondary battery is obtained.

[0272] Example 2-22 The battery preparation methods of Examples 2-22 are basically the same as those of Example 1, except that the preparation methods of the positive electrode active materials are different. The positive electrode active materials prepared in Preparation Examples 2-22 are used respectively.

[0273] Comparative Examples 1-3 The battery preparation methods of Comparative Examples 1-3 are basically the same as those of Example 1, except that the preparation methods of the positive electrode active materials are different. The positive electrode active materials prepared in Comparative Examples 1-3 are respectively used.

[0274] Comparative Example 4 The preparation method of the battery of Comparative Example 4 is basically the same as that of Example 1, except that the preparation method of the positive electrode active material is different. 0.9 Co 0.05 Mn 0.05 O2 is used as the positive electrode active material to prepare battery cells.

[0275] 3. Battery performance test (1) DSC test At 25°C, the battery cells were charged at a constant current of 0.5C to a cutoff voltage of 4.35V, then charged at a constant voltage of 4.35V to 0.05C. The fully charged battery cells were disassembled, and the fully charged positive and negative electrode plates were removed and cleaned. The plates were then punched into small discs with a diameter of 5mm and placed in a stainless steel sealed crucible commonly used in DSC (differential scanning calorimetry) equipment. 1.5μL of the corresponding electrolyte was injected, and the threads of the sealed crucible were tightened. Finally, the cells were tested in a NETZSCH DSC300 Caliris Classic instrument at a heating rate of 10°C / min over a temperature range of 30°C-460°C. According to the test results, the ordinate of the DSC curve represents the heat generation rate in mW, and the integrated area of ​​the DSC curve and the abscissa represents the heat generation.

[0276] (2) Thermal safety test At 25°C, charge the battery cells at a constant current of 0.5C to a cutoff voltage of 4.35V, then charge at a constant voltage of 4.35V to 0.05C. Secure the fully charged battery cells on their large surfaces with a heating plate (JK-HP-180A / 180B). Apply a 220V / 3A signal to the heating plate and heat the cells at this constant power until the hard-shelled cells fail or the heating duration reaches two hours. Thermal runaway pass criteria: The safety valve of the cell opens in a directional manner, with no cracks on the large surfaces or side shells. Heating for two hours without thermal runaway is considered a passing condition.

[0277] (3) Dynamic performance test At 25°C, the battery cell was charged at a constant current of 0.5C to a cut-off voltage of 4.35V, and then charged at a constant voltage of 4.35V to 0.05C. It was then discharged at a constant current of 0.02C to a cut-off voltage of 2.5V, and the full discharge capacity C0 of the battery cell was recorded.

[0278] At 25°C, the battery cell was charged at a constant current of 0.5C to a cut-off voltage of 4.35V, and then charged at a constant voltage of 4.35V to 0.05C. It was then discharged at a constant current of 2C to a cut-off voltage of 2.5V, and the full discharge capacity C1 of the battery cell was recorded.

[0279] According to the formula: 2C discharge capacity retention rate = (C1 / C0) × 100%, the 2C discharge capacity retention rate of the battery cell is calculated to evaluate the dynamic performance of the battery cell.

[0280] (4) Gravimetric energy density Allow the battery cell to rest at 25°C for 2 hours. At 25°C, charge the cell at a nominal capacity of 0.33C to a charge cutoff voltage of 4.35V. Allow the cell to rest for 10 minutes, then perform constant voltage charging at 4.35V until the current reaches 0.05C, at which point the charge is cutoff. Allow the cell to rest at 25°C for 1 hour, then discharge the cell at 0.33C at 25°C to a discharge cutoff voltage of 2.5V. Record the total discharge energy of the cell as E0 (Wh). Measure the weight of the cell as M0 (kg). The gravimetric energy density of the cell is calculated as: cell discharge energy E0 / cell weight M0 (Wh / kg).

[0281] 4. Analysis of test results of various embodiments and comparative examples The performance parameters of the positive electrode active material and battery cells were measured according to the above method, and the DSC test results were as follows: Figure 4 As shown, the thermal safety performance and dynamic performance results are shown in Tables 2 to 5 below.

[0282] Table 2

[0283] Figure 4 These are the DSC test results of Comparative Example 4, Example 1, Example 7, and Example 21 of this application. Figure 4 It can be seen that compared with Comparative Example 4, Example 1, Example 7, and Example 21 can all reduce the heat generation of the battery cell or increase the critical temperature of thermal runaway of the battery cell.

[0284] Scanning electron microscopy and energy dispersive spectroscopy analysis characterized the positive electrode active materials prepared in the examples. The results showed that the total molar ratio of Li to M elements (Ni, Co, and Mn) near the surface of the layered transition metal oxide particles was greater than the molar ratio near the center of the particles. In contrast, in the positive electrode active materials of the comparative examples, the total molar ratio of Li to M elements (Ni, Co, and Mn) near the surface of the layered transition metal oxide particles was less than or equal to the molar ratio near the center of the particles. These experimental results demonstrate that the battery cells of the examples of this application exhibit superior thermal safety performance.

[0285] The weight energy density of the battery cell of Example 1 measured by the above method is 426Wh / kg. The experimental results show that the battery cell of the embodiment of the present application has a high energy density.

[0286] According to Comparative Examples 1-4 and Examples 1, 3 and 5, it can be seen that by coating the surface of the layered transition metal oxide particles with tantalum-doped lithium lanthanum zirconium oxide Li 6.4 La3Zr y1 Ta y2 O 12 , 0<y1<2 and 0<y2<2, lithium aluminum titanium phosphate oxide Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 or lithium aluminum phosphate oxide LiAl3Ti2(PO4)3 and sintering can significantly improve the thermal safety performance of the battery cell while taking into account the dynamic performance.

[0287] According to Examples 1-6, when the primary sintering temperature is between 600°C and 900°C, the thermal safety performance of the battery cell can be significantly improved while taking into account the dynamic performance.

[0288] Table 3

[0289] According to Examples 8-11, when the solid electrolyte mass ratio is within the range of 1.5%-10%, the battery cell has good thermal safety and kinetic performance. When the solid electrolyte mass ratio is within the range of 3%-7%, the battery cell has a better thermal safety test pass rate while taking into account kinetic performance.

[0290] Table 4

[0291] As can be seen from Examples 12-19, the present invention provides a method for preparing a positive electrode active material, comprising: coating layered transition metal oxide particles with a solid electrolyte to obtain a coated product; and sintering the coated product once to obtain a positive electrode active material; the solid electrolyte comprises one or more of lithium aluminum titanium phosphate oxide, lithium aluminum phosphate oxide, and tantalum-doped lithium lanthanum zirconium oxide. The positive electrode active material prepared by this method exhibits excellent thermal safety, kinetic performance, and high energy density.

[0292] According to Examples 8-11, when the primary sintering temperature is 800°C-1000°C and the primary sintering time is within the range of 2h-8h, the battery cells have a better thermal safety test pass rate while ensuring the dynamic performance.

[0293] Table 5

[0294] As can be seen from Examples 20-22, the present invention provides a method for preparing a positive electrode material, comprising: heat-treating a first mixture comprising a layered transition metal oxide precursor to obtain a sintered product; mixing the sintered product with a solid electrolyte and performing a second heat treatment to obtain a positive electrode active material, wherein the solid electrolyte comprises one or more of lithium aluminum titanium phosphate oxide and lithium aluminum phosphate oxide. The positive electrode active material prepared by this method exhibits excellent thermal safety, kinetic performance, and high energy density.

[0295] According to Comparative Example 4 and Example 22, the positive electrode active material prepared in the examples of the present application has good thermal safety performance, kinetic performance and high energy density.

[0296] According to Comparative Example 4 and Example 21, the positive electrode active material prepared in the examples of the present application has good thermal safety performance, kinetic performance and high energy density, and reduces the production cost.

[0297] According to Comparative Example 4 and Example 20, the positive electrode active material prepared in the examples of the present application has good thermal safety performance, kinetic performance and high energy density, and further reduces the production cost.

[0298] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, characterized in that: The battery cell includes a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the surface of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes layered transition metal oxide particles, the layered transition metal oxide particles include a general formula of Li a M b O c Components, wherein 0.8≤a≤1.3, 0.8<b≤1, 1.5<c≤2, M includes one or more of Ni, Co, Mn, and Al; In the cross section of the layered transition metal oxide particle, the molar ratio of the Li element to the M element near the surface is greater than the molar ratio of the Li element to the M element near the center of the particle.

2. The battery cell according to claim 1, wherein: The surface of the layered transition metal oxide particles is further provided with a coating layer, and the coating layer includes a solid electrolyte.

3. The battery cell according to claim 2, characterized in that: The solid electrolyte includes one or more of lithium aluminum titanium phosphate oxide, lithium aluminum phosphate oxide, and tantalum-doped lithium lanthanum zirconium oxide.

4. The battery cell according to claim 3, characterized in that The general formula of the tantalum-doped lithium lanthanum zirconium oxide is shown in Formula I, Li 6.4 La3Zr y1 Ta y2 O 12 , 0<y1<2 and 0<y2<2 Formula I.

5. The battery cell according to claim 3, characterized in that: The general formula of the lithium aluminum titanium phosphate oxide is shown in Formula II, Li x1 Al x2 Ti x3 (PO4)3, 1.5≤x1<3, 0.2≤x2<2 and 0≤x3<1.8 Formula II; the lithium aluminum phosphate oxide is Li3Al2(PO4)3.

6. The battery cell according to claim 2, characterized in that The coating layer has a thickness of 0.02 μm to 2 μm.

7. The battery cell according to claim 2, characterized in that: The layered transition metal oxide particles are doped with La, Zr and Ta elements.

8. The battery cell according to claim 7, characterized in that In the cross section of the layered transition metal oxide particle, the mass contents of La, Zr and Ta elements near the surface are respectively greater than the mass contents of La, Zr and Ta elements near the center.

9. The battery cell according to claim 2, characterized in that: The layered transition metal oxide particles are doped with Al, Ti and P, and M includes one or more of Ni, Co and Mn.

10. The battery cell according to claim 9, characterized in that: In the cross section of the layered transition metal oxide particle, the mass contents of the Al element, the Ti element, and the P element near the surface are respectively greater than the mass contents of the Al element, the Ti element, and the P element near the center.

11. The battery cell according to claim 1, characterized in that: The layered transition metal oxide particles are doped with Al, Ti and P elements. In the cross section of the layered transition metal oxide particle, the molar ratio of the Li element to the P element near the surface is greater than the molar ratio of the Li element to the P element near the center.

12. The battery cell according to claim 11, characterized in that: The layered transition metal oxide particles are doped with Al, Ti and P, and M includes one or more of Ni, Co and Mn. In the cross section of the layered transition metal oxide particle, the molar ratio of Al element to Ti element near the surface is greater than the molar ratio of Al element to Ti element near the center.

13. The battery cell according to claim 12, characterized in that: In the cross section of the layered transition metal oxide particles, the molar ratio of Al element, Ti element and P element is (1-2):(0-1):3 from the surface to the outer region of 1 μm to 3 μm in the direction toward the geometric center.

14. The battery cell according to claim 12, characterized in that: In the cross section of the layered transition metal oxide particles, in a core region with a diameter of 3 μm to 10 μm and a circle centered at the geometric center, the molar ratio of Al element, Ti element, and P element is (0.2-1):(1-1.8):

3.

15. The battery cell according to claim 12, characterized in that In a cross section of the layered transition metal oxide particle, in a core region with a diameter of 3 μm to 7 μm and a circle centered at the geometric center, the molar ratio of Al element, Ti element, and P element is (0.2-0.8):(1.2-1.8):3; In an outer region of 1 μm to 3 μm from the surface toward the geometric center, the molar ratio of Al element, Ti element, and P element is (1.2-2):(0-0.8):3; The thickness of the middle region between the core region and the outer region is 1 μm-3 μm. In the middle region, the molar ratio of Al element, Ti element and P element is (0.8-1.2):(0.8-1.2):

3.

16. The battery cell according to claim 1, characterized in that The Dv50 of the positive electrode active material is 10 μm-15 μm.

17. A battery device, characterized in that: Comprising the battery cell according to any one of claims 1 to 16, the battery device comprises one or more of a battery module, a battery pack, and an energy storage battery.

18. An electrical device, characterized in that: The electrical device comprises the battery device as claimed in claim 17, and the battery device is used to provide electrical energy.

19. An energy storage device, characterized in that: The energy storage device comprises the battery device according to claim 17, wherein the battery device is used to store electrical energy.

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