Positive electrode sheet, solid-state battery cell, battery device, electric device, and positive electrode active material and preparation method therefor

Abstract

Provided in the present disclosure are a positive electrode sheet, a solid-state battery cell, a battery device, an electric device, and a positive electrode active material and a preparation method therefor. The positive electrode sheet comprises a positive electrode active material and a sulfide solid-state electrolyte material, wherein the positive electrode active material comprises a substrate material, a cobalt-rich material located on the surface of the substrate material and a coating material located on at least part of the surface of the cobalt-rich material; the substrate material comprises a transition metal oxide, the cobalt-rich material comprises a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than that of Co in the substrate material; and the coating material comprises an electrolyte salt material. When applied to a solid-state battery cell, the positive electrode sheet can reduce the capacity fade rate of the solid-state battery cell at high temperatures and improve the high-temperature cycle performance of the solid-state battery cell.

Description

Positive electrode sheet, solid-state battery cell, battery device, electrical device, positive electrode active material and its preparation method

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411215789.2, filed on August 30, 2024, entitled “Positive electrode sheet, solid-state battery cell, battery device, power device, positive electrode active material and preparation method thereof”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a positive electrode sheet, a solid-state battery cell, a battery device, an electrical device, a positive electrode active material, and a method for preparing the same. Background Technology

[0004] Compared to liquid-state battery cells, solid-state battery cells use solid electrolyte materials, which are less prone to combustion and explosion, thus offering higher reliability. However, solid-state battery cells suffer from rapid capacity decay at high temperatures. Summary of the Invention

[0005] This disclosure provides a positive electrode sheet, a solid-state battery cell, a battery device, an electrical device, a positive electrode active material, and a method for preparing the same. The positive electrode sheet is applied to a solid-state battery cell, which can reduce the capacity decay rate of the solid-state battery cell at high temperatures and improve the high-temperature cycle performance of the solid-state battery cell.

[0006] In a first aspect, this disclosure provides a positive electrode sheet, which includes a positive electrode active material and a sulfide solid electrolyte material. The positive electrode active material includes a matrix material, a cobalt-rich material located on the surface of the matrix material, and a coating material located on at least a portion of the surface of the cobalt-rich material. The matrix material includes a transition metal oxide, the cobalt-rich material includes a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than the molar content of Co in the matrix material. The coating material includes an electrolyte salt material.

[0007] The positive electrode active material disclosed herein includes a cobalt-rich material located on the surface of a matrix material and a coating material located on at least a portion of the surface of the cobalt-rich material. The matrix material includes transition metal oxides, and the cobalt-rich material includes Co-containing transition metal oxides. Therefore, the cobalt-rich material and the matrix material can have good affinity and structural compatibility, thereby improving the overall structural stability of the positive electrode active material. Furthermore, the molar content of Co in the cobalt-rich material is greater than that in the matrix material. Thus, the cobalt-rich material located on the surface of the matrix material can also slow down the decomposition of the sulfide solid electrolyte material by the matrix material, thereby improving the interfacial stability between the positive electrode active material and the sulfide solid electrolyte material. The coating material includes an electrolyte salt material, the elastic modulus of which is much smaller than that of the matrix material. This allows for a larger coating area, further reducing side reactions between the matrix material and the sulfide solid electrolyte material. Therefore, the positive electrode active material and the sulfide solid electrolyte material of the positive electrode sheet disclosed herein exhibit good high-temperature stability. When applied to solid-state battery cells, this positive electrode sheet can reduce the capacity decay rate of solid-state battery cells at high temperatures and improve the high-temperature cycle performance of solid-state battery cells.

[0008] In some embodiments, the coating material includes a fluorinated electrolyte salt material. The fluorinated electrolyte salt material exhibits good high-temperature and high-pressure stability. During charging, it can decompose before the sulfide solid electrolyte material to generate LiF, thereby reducing the decomposition of the sulfide solid electrolyte material, improving the high-temperature stability of both the positive electrode active material and the sulfide solid electrolyte material, reducing the capacity decay rate of the solid-state battery cell at high temperatures, and improving the high-temperature cycle performance of the solid-state battery cell.

[0009] In some embodiments, the coating material includes one or more of Li₂PO₂F₂, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate. Within the aforementioned range, the coating material can pre-decompose the sulfide solid electrolyte material to generate LiF, which coats the surface of the cobalt-rich material. This reduces the decomposition of the sulfide solid electrolyte material, improves the high-temperature stability of both the positive electrode active material and the sulfide solid electrolyte material, and also gives the positive electrode active material high ionic conductivity, thereby further improving the high-temperature cycle performance of the solid-state battery cell. Furthermore, these coating materials have low elastic modulus, allowing for larger area coating and further reducing side reactions between the matrix material and the sulfide solid electrolyte material.

[0010] In some embodiments, the mass fraction of the coating material is 0.1%-3% based on the total mass of the positive electrode active material (100%). A mass fraction of coating material within this range can enable the positive electrode active material to possess high ionic conductivity and high specific capacity.

[0011] In some embodiments, the coating material is located on 90% to 100% of the surface of the cobalt-rich material. This can further reduce side reactions between the matrix material and the sulfide solid electrolyte material, reduce the capacity decay rate of solid-state battery cells at high temperatures, and improve the high-temperature cycling performance of solid-state battery cells.

[0012] In some embodiments, the thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm. A thickness within this range can improve the high-temperature stability of both the positive electrode active material and the sulfide solid electrolyte material, while also enabling the positive electrode active material to possess a high specific capacity.

[0013] In some embodiments, the matrix material includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-rich manganese-based materials.

[0014] In some embodiments, cobalt-rich materials include one or more of cobalt-rich lithium nickel cobalt manganese oxide, cobalt-rich lithium nickel cobalt aluminum oxide, and cobalt-rich lithium manganese-based materials.

[0015] In some embodiments, the matrix material comprises a Ni-containing transition metal oxide, and the cobalt-rich material comprises a Ni- and Co-containing transition metal oxide, wherein the molar content of Ni in the cobalt-rich material is less than the molar content of Ni in the matrix material. This allows solid-state battery cells to achieve both high energy density and good high-temperature cycling performance.

[0016] In some embodiments, the cobalt-rich material is located on 100% of the surface of the matrix material.

[0017] In some embodiments, there is no interface between the cobalt-rich material and the substrate material. This lack of an interface allows for better affinity and structural compatibility between the cobalt-rich material and the substrate material, thereby further enhancing the overall structural stability of the cathode active material.

[0018] In some embodiments, the positive electrode active material further includes metal particles located between the cobalt-rich material and the coating material, the metal particles including one or more of elemental cobalt particles and cobalt oxide particles.

[0019] In some embodiments, the average particle size of the positive electrode active material is 3 μm-10 μm.

[0020] In some embodiments, the average particle size of the sulfide solid electrolyte material is 1 nm-20 μm.

[0021] In some embodiments, the mass ratio of the positive electrode active material to the sulfide solid electrolyte material is from 99:1 to 70:30. A mass ratio of positive electrode active material to sulfide solid electrolyte material within this range allows the solid-state battery cell to possess high energy density, high ion transport characteristics, and good cycle performance.

[0022] In some embodiments, the positive electrode sheet further includes a positive electrode conductive agent and / or a positive electrode binder.

[0023] In some embodiments, the positive electrode sheet further includes a positive current collector, and the positive active material and the sulfide solid electrolyte material are located on at least one surface of the positive current collector.

[0024] In a second aspect, this disclosure provides a solid-state battery cell, which includes a negative electrode, a solid electrolyte membrane, and a positive electrode, wherein the solid electrolyte membrane is located between the negative electrode and the positive electrode.

[0025] In some embodiments, the negative electrode includes one or more of lithium, lithium alloy, natural graphite, artificial graphite, mesophase micro carbon spheres, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and metal oxides.

[0026] In some embodiments, the solid electrolyte membrane includes one or more of sulfide solid electrolyte materials, halide solid electrolyte materials, and oxide solid electrolyte materials.

[0027] Thirdly, this disclosure provides a battery device comprising a plurality of solid-state battery cells as described in the second aspect.

[0028] Fourthly, this disclosure provides an electrical device that includes a solid-state battery cell (as described in the second aspect) or a battery device (as described in the third aspect).

[0029] Fifthly, this disclosure provides a positive electrode active material, which includes a matrix material, a cobalt-rich material located on the surface of the matrix material, and a coating material located on at least a portion of the surface of the cobalt-rich material; the matrix material includes a transition metal oxide, the cobalt-rich material includes a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than the molar content of Co in the matrix material; the coating material includes an electrolyte salt material.

[0030] In a sixth aspect, this disclosure provides a method for preparing a positive electrode active material, comprising the following steps: providing a matrix material, a cobalt source material, and a coating material, wherein the matrix material comprises a transition metal oxide, and the coating material comprises an electrolyte salt material; mixing the matrix material and the cobalt source material and performing a first heating treatment in an oxygen-containing atmosphere to obtain an intermediate material; mixing the obtained intermediate material and the coating material and performing a second heating treatment in an oxygen-containing atmosphere to obtain a positive electrode active material, wherein the positive electrode active material comprises a matrix material, a cobalt-rich material located on the surface of the matrix material, and a coating material located on at least a portion of the surface of the cobalt-rich material, wherein the matrix material comprises a transition metal oxide, the cobalt-rich material comprises a Co-containing transition metal oxide, and the molar content of Co element in the cobalt-rich material is greater than the molar content of Co element in the matrix material, and the coating material comprises an electrolyte salt material.

[0031] In some embodiments, the temperature of the first heat treatment is 500°C-800°C.

[0032] In some embodiments, the first heat treatment lasts for 0.5 h to 10 h.

[0033] In some embodiments, the temperature of the second heat treatment is 300°C-400°C.

[0034] In some embodiments, the second heat treatment lasts for 0.5-5 hours.

[0035] In some embodiments, the cobalt source material includes one or both of cobalt hydroxide and cobalt oxide. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0037] Figure 1 shows a schematic diagram of a solid-state battery cell provided in some embodiments of this disclosure.

[0038] Figure 2 shows a schematic diagram of an electrical device provided in some embodiments of this disclosure.

[0039] Figure 3 shows a schematic diagram of the structure of the positive electrode active material provided in some embodiments of this disclosure.

[0040] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0041] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the positive electrode sheet, solid-state battery cell, battery device, power supply device, positive electrode active material, and preparation method thereof. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for a full understanding of this disclosure by those skilled in the art and are not intended to limit the subject matter of the claims.

[0042] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0044] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0045] Unless otherwise specified, all steps in this disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] Unless otherwise specified, in this disclosure, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0047] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0048] In the description of the embodiments of this disclosure, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0049] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0050] The solid-state battery cell mentioned in the embodiments of this disclosure can independently perform charge and discharge functions. After discharge, it can be reactivated by charging to allow the active materials to continue to be used. The solid-state battery cell can be cylindrical, cuboid, or other shapes, etc., and the embodiments of this disclosure are not limited to this. Figure 1 shows a cuboid solid-state battery cell 5 as an example.

[0051] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple solid-state battery cells, which are connected in series, parallel, or mixed connections via busbars.

[0052] In some embodiments, a battery cell assembly is typically formed by arranging multiple solid-state battery cells.

[0053] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple solid-state battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple solid-state battery cells together with cable ties.

[0054] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0055] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0056] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple solid-state battery cells to the housing.

[0057] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0058] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0059] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0060] The technical solutions described in this disclosure are applicable to various electrical devices that use solid-state battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Solid-state battery cells and battery devices are used to store or provide electrical energy.

[0061] Figure 2 is a schematic diagram of an example electrical device. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0062] The solid-state battery cell provided in the embodiments of this disclosure includes an electrode assembly and an outer packaging, the outer packaging being used to encapsulate the electrode assembly. The outer packaging can be a rigid shell, such as a rigid plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0063] Solid-state battery cells typically use high-potential transition metal oxide cathode active materials. Due to the difference in electrochemical potential between transition metal oxide cathode active materials and sulfide solid electrolyte materials, interfacial side reactions inevitably occur, and the generated interfacial byproducts increase the impedance of solid-state battery cells, hindering ion transport. At the same time, the oxygen released by the transition metal oxide cathode active material during charging will also oxidize the sulfide solid electrolyte material, thereby causing even more serious interfacial side reactions.

[0064] Currently, oxides, such as Li₂NbO₃ and Li₂ZrO₃, are often used to coat transition metal oxide cathode active materials to reduce interfacial side reactions between the transition metal oxide cathode active materials and sulfide solid electrolyte materials. This allows solid-state battery cells to have good cycle performance at room temperature. However, when solid-state battery cells are charged and discharged at high temperatures (e.g., >50°C), the interfacial side reactions between the transition metal oxide cathode active materials and sulfide solid electrolyte materials become more severe, and conventional oxide coating materials cannot effectively improve the capacity decay of solid-state battery cells at high temperatures.

[0065] Based on this, the present disclosure provides a positive electrode active material and a positive electrode sheet containing the same, which is applied to a solid-state battery cell to reduce the capacity decay rate of the solid-state battery cell at high temperatures and improve the high-temperature cycle performance of the solid-state battery cell.

[0066] The positive electrode sheet disclosed herein includes a positive electrode active material and a sulfide solid electrolyte material.

[0067] As shown in Figure 3, the positive electrode active material of this disclosure includes a substrate material 100, a cobalt-rich material 101 located on the surface of the substrate material 100, and a coating material 102 located on at least a portion of the surface of the cobalt-rich material 101. The substrate material 100 includes a transition metal oxide, the cobalt-rich material 101 includes a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than the molar content of Co in the substrate material. The coating material 102 includes an electrolyte salt material.

[0068] The positive electrode active material disclosed herein includes a cobalt-rich material located on the surface of a matrix material and a coating material located on at least a portion of the surface of the cobalt-rich material. The matrix material includes transition metal oxides, and the cobalt-rich material includes Co-containing transition metal oxides. Therefore, the cobalt-rich material and the matrix material can have good affinity and structural compatibility, thereby improving the overall structural stability of the positive electrode active material. In addition, the molar content of Co in the cobalt-rich material is greater than that in the matrix material. Thus, the cobalt-rich material located on the surface of the matrix material can also slow down the decomposition of the sulfide solid electrolyte material by the matrix material, thereby improving the interfacial stability between the positive electrode active material and the sulfide solid electrolyte material.

[0069] The coating material includes electrolyte salt material, whose elastic modulus is much smaller than that of the matrix material, thus enabling a larger coating area and further reducing side reactions between the matrix material and the sulfide solid electrolyte material.

[0070] Therefore, the positive electrode active material and the sulfide solid electrolyte material of the positive electrode sheet disclosed herein have good high-temperature stability. When this positive electrode sheet is applied to a solid-state battery cell, it can reduce the capacity decay rate of the solid-state battery cell at high temperatures and improve the high-temperature cycle performance of the solid-state battery cell.

[0071] In some embodiments, the matrix material may include one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-rich manganese-based materials.

[0072] In some embodiments, cobalt-rich materials may include one or more of cobalt-rich lithium nickel cobalt manganese oxide, cobalt-rich lithium nickel cobalt aluminum oxide, and cobalt-rich lithium manganese-based materials.

[0073] In some embodiments, the matrix material may include lithium nickel cobalt manganese oxide, and the cobalt-rich material may include cobalt-rich lithium nickel cobalt manganese oxide.

[0074] In some embodiments, the matrix material may include lithium nickel cobalt aluminum oxide, and the cobalt-rich material may include cobalt-rich lithium nickel cobalt aluminum oxide.

[0075] In some embodiments, the matrix material may include lithium-rich manganese-based materials, and the cobalt-rich material may include cobalt-rich lithium-rich manganese-based materials.

[0076] In some embodiments, the cobalt-rich material may be located on 100% of the surface of the matrix material.

[0077] In some embodiments, there is no interface between the cobalt-rich material and the substrate material. This lack of an interface allows for better affinity and structural compatibility between the cobalt-rich material and the substrate material, thereby further enhancing the overall structural stability of the cathode active material.

[0078] In some embodiments, the matrix material may include a transition metal oxide containing Ni, and the cobalt-rich material may include a transition metal oxide containing Ni and Co, and the molar content of Ni in the cobalt-rich material may be less than the molar content of Ni in the matrix material.

[0079] The matrix material includes a Ni-containing transition metal oxide, and the molar content of Ni in the matrix material is greater than that in the cobalt-rich matrix material, thereby enabling the positive electrode active material to have a high specific capacity. Typically, the side reactions between transition metal oxides with high Ni content and sulfide solid electrolyte materials are quite severe, thus affecting the capacity decay of solid-state battery cells at high temperatures. This disclosure involves depositing a cobalt-rich material and a coating material on the surface of the matrix material. The cobalt-rich material can mitigate the decomposition of the sulfide solid electrolyte material by the matrix material, improving the interfacial stability between the positive electrode active material and the sulfide solid electrolyte material. The coating material includes an electrolyte salt material, whose elastic modulus is much smaller than that of the matrix material, thereby achieving a larger coating area. This further reduces the side reactions between the matrix material and the sulfide solid electrolyte material, enabling the solid-state battery cell to achieve both high energy density and good high-temperature cycling performance.

[0080] In some embodiments, the matrix material may include materials of the general formula Li a Ni b Co c M d O e A f The material has the following properties: 0.8≤a≤1.2, 0<b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1. M may include one or more elements from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B. A may include one or more elements from N, F, S and Cl.

[0081] Alternatively, 0.3≤b<1, 0.5≤b<1, 0.6≤b<1, 0.8≤b<1, and 0.83≤b<1.

[0082] A high Ni content in the matrix material can give the positive electrode active material a high specific capacity, enabling solid-state battery cells to achieve both high energy density and good high-temperature cycling performance.

[0083] As an example, the matrix material may include, but is not limited to, LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.83 Mn 0.08 Co 0.07 O2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O2 (abbreviated as Ni94), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), LiNi 0.85 Co 0.1 Al 0.05 One or more of O2.

[0084] Optionally, the matrix material may include, but is not limited to, LiNi. 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.83 Mn 0.08 Co 0.07 O2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O2 (abbreviated as Ni94), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), LiNi 0.85 Co 0.1 Al 0.05 One or more of O2.

[0085] During the charging and discharging process, solid-state battery cells undergo Li insertion / extraction and consumption, resulting in varying Li molar content at different discharge states. In the examples of matrix materials listed in this disclosure, the Li molar content represents the initial state of the material, i.e., the state before material input. As the matrix material is applied to the solid-state battery cell, the Li molar content changes after charge-discharge cycles. Similarly, the O molar content listed in the examples of matrix materials in this disclosure is only a theoretical value. Lattice oxygen release causes changes in the O molar content, leading to fluctuations in the actual O molar content.

[0086] In some embodiments, cobalt-rich materials may include those with the general formula Li a1 Ni b1 Co c1 M 1 d1 O e1 A 1 f1 The material has the following properties: 0.8 ≤ a1 ≤ 1.2, 0 < b1 < 1, 0 < c1 < 1, 0 < d1 < 1, 1 ≤ e1 ≤ 2, 0 ≤ f1 ≤ 1, M 1 It may include one or more elements selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, A 1 It can include one or more elements from N, F, S and Cl.

[0087] Optionally, c < c1.

[0088] Optionally, b > b1.

[0089] In some embodiments, the thickness of the cobalt-rich material can range from 0.5 nm to 50 nm, for example, it can be 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, or any combination of the above values.

[0090] The thickness range of cobalt-rich materials is within the above range, which can improve the high-temperature stability of the positive electrode active material and the sulfide solid electrolyte material, and also enable the positive electrode active material to have a high specific capacity.

[0091] The thickness range of cobalt-rich materials can be determined by obtaining cross-sectional images of the positive electrode active material particles through EDS (energy dispersive spectroscopy) elemental analysis combined with TEM (transmission electron microscopy) or SEM (scanning electron microscopy) surface scanning, and then based on the Co elemental distribution in the cross-sectional images. During testing, a cross-section polishing instrument can be used to prepare the cross-section of the positive electrode active material particles, passing through the core of the particles.

[0092] In some embodiments, the coating material may include a fluorinated electrolyte salt material.

[0093] Fluorinated electrolyte salt materials have good high-temperature stability and high-pressure stability. During the charging process, they can decompose to form LiF before sulfide solid electrolyte materials, thereby reducing the decomposition of sulfide solid electrolyte materials, improving the high-temperature stability of positive electrode active materials and sulfide solid electrolyte materials, reducing the capacity decay rate of solid battery cells at high temperatures, and improving the high-temperature cycle performance of solid battery cells.

[0094] In some embodiments, the coating material may include one or more of Li2PO2F2, lithium difluorooxalate borate (LiDFOB), lithium difluorodioxalate phosphate (LiDFBOP), and lithium tetrafluorooxalate phosphate (LiOTFP).

[0095] Within the aforementioned range, the coating material can decompose before the sulfide solid electrolyte material to generate LiF, which coats the surface of the cobalt-rich material. This reduces the decomposition of the sulfide solid electrolyte material, improves the high-temperature stability of both the cathode active material and the sulfide solid electrolyte material, and also imparts high ionic conductivity to the cathode active material, thereby further enhancing the high-temperature cycle performance of the solid-state battery cell. Furthermore, these coating materials have a low elastic modulus, allowing for larger-area coating and further reducing side reactions between the matrix material and the sulfide solid electrolyte material.

[0096] In some embodiments, based on the total mass of the positive electrode active material as 100%, the mass fraction of the coating material can be 0.1%-3%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, or any range of the above values.

[0097] When the mass fraction of the coating material is within the above range, the positive electrode active material can have high ionic conductivity and high specific capacity.

[0098] In some embodiments, the coating material may be located on 90% to 100% of the surface of the cobalt-rich material. Optionally, the coating material may be located on 100% of the surface of the cobalt-rich material.

[0099] This can further reduce side reactions between the matrix material and the sulfide solid electrolyte material, reduce the capacity decay rate of solid-state battery cells at high temperatures, and improve the high-temperature cycling performance of solid-state battery cells.

[0100] In some embodiments, the positive electrode active material may further include metal particles located between the cobalt-rich material and the coating material, and the metal particles may include one or more of cobalt elemental particles and cobalt oxide particles.

[0101] In some embodiments, the average particle size of the positive electrode active material may be 3 μm - 10 μm, for example, it may be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range composed of any of the above values.

[0102] In some embodiments, the positive electrode active material may be single crystal or polycrystalline.

[0103] In some embodiments, the sulfide solid electrolyte material may include one or more of Li6PS5X, LGPS-based sulfide solid electrolyte materials, and polyvalent sulfide solid electrolyte materials, where X includes one or more elements of F, Cl, Br, and I.

[0104] Optionally, the LGPS-based sulfide solid electrolyte material may include Li 10±δ5 Ge 1-g G g P 2-q Q q S 12-w W w , 0 ≤ δ5 < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G includes one or two elements of Si and Sn, Q includes Sb, and W includes one or more elements of O, Se, Te, Cl, Br, I, and F.

[0105] Optionally, the polyvalent sulfide solid electrolyte material may include one or more of Li2S - P2S5, Li2S - SiS2, Li2S - GeS2, (100 - u - v)Li2S·uP2S5·vM m N n where 0 < u < 100, 0 < v < 100, 0 < u + v < 100, 0 ≤ m < 4, 0 ≤ n < 6, M includes one or more elements of Li, B, Ge, Si, Sn, and Sb, and N includes one or more elements of S, Se, Te, O, Cl, Br, I, and F.

[0106] In some embodiments, by way of example, the sulfide solid electrolyte material may include one or more of Li6PS5Cl, Li6PS5Br, Li 10 GeP2S 12 , Li3PS4, Li7P3S 11 among others.

[0107] In some embodiments, the average particle size of the sulfide solid electrolyte material can be 1 nm to 20 μm, for example, it can be 1 nm, 10 nm, 20 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, or any combination of the above values. Optionally, the average particle size of the sulfide solid electrolyte material can be 50 nm to 5 μm.

[0108] In some embodiments, the mass ratio of the positive electrode active material to the sulfide solid electrolyte material can be from 99:1 to 70:30, for example, it can be 99:1, 98:2, 97:3, 96:4, 95:5, 94:6, 93:7, 92:8, 91:9, 90:10, 89:11, 88:12, 87:13, 86:14, 85:15, 84:16, 83:17, 82:18, 81:19, 80:20, 79:21, 78:22, 77:23, 76:24, 75:25, 74:26, 73:27, 72:28, 71:29, 70:30, or any range of the above values.

[0109] When the mass ratio of positive electrode active material to sulfide solid electrolyte material is within the above range, solid-state battery cells can have high energy density, high ion transport characteristics, and good cycle performance.

[0110] Optionally, the mass ratio of the positive electrode active material to the sulfide solid electrolyte material can be 95:5 to 70:30, 90:10 to 70:30, 85:15 to 70:30, 95:5 to 72:28, 90:10 to 72:28, or 85:15 to 72:28.

[0111] In some embodiments, the positive electrode sheet may further include a positive electrode binder, which may include, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, water-soluble unsaturated resin SR-1B, methyl vinyl silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), styrene-butadiene rubber (SBR), thermoplastic styrene-butadiene rubber (SBS), isoprene rubber, cis-butadiene rubber (BR), ethyl cellulose, polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), fluororubber, and acrylate rubber, or one or more of these.

[0112] In some embodiments, the positive electrode sheet may further include a positive electrode conductive agent, which may include, but is not limited to, one or more of conductive graphite (such as KS-6, SFG-6), superconducting carbon, acetylene black, carbon black (such as SP), Ketjen black (such as ECP), carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0113] The positive electrode may or may not include a positive current collector.

[0114] In some embodiments, the positive electrode sheet may include a positive current collector and a positive electrode film layer located on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material and a sulfide solid electrolyte material.

[0115] The positive electrode current collector has two surfaces opposite 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.

[0116] In some embodiments, the positive electrode film layer may further include a positive electrode binder, which may include, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, water-soluble unsaturated resin SR-1B, methyl vinyl silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), styrene-butadiene rubber (SBR), thermoplastic styrene-butadiene rubber (SBS), isoprene rubber, cis-butadiene rubber (BR), ethyl cellulose, polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), fluororubber, and acrylate rubber, or one or more of these.

[0117] In some embodiments, the positive electrode film may further include a positive electrode conductive agent, which may include, but is not limited to, one or more of conductive graphite (such as KS-6, SFG-6), superconducting carbon, acetylene black, carbon black (such as SP), Ketjen black (such as ECP), carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0118] In some embodiments, the positive current collector may be a metal foil or a composite current collector. Examples of metal foils include stainless steel foil, carbon-coated aluminum foil, aluminum foil, nickel foil, and titanium foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. Examples of metal materials include, but are not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer substrates include, but are not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene.

[0119] Positive electrode sheets can be prepared using either dry or wet processes.

[0120] This disclosure also provides a method for preparing a positive electrode active material, which can prepare the above-mentioned positive electrode active material.

[0121] The preparation method of the positive electrode active material includes the following steps: providing a matrix material, a cobalt source material, and a coating material, wherein the matrix material includes a transition metal oxide, and the coating material includes an electrolyte salt material; mixing the matrix material and the cobalt source material and performing a first heating treatment in an oxygen-containing atmosphere to obtain an intermediate material; mixing the obtained intermediate material and the coating material and performing a second heating treatment in an oxygen-containing atmosphere to obtain the positive electrode active material. The positive electrode active material includes a matrix material, a cobalt-rich material located on the surface of the matrix material, and a coating material located on at least a portion of the surface of the cobalt-rich material. The matrix material includes a transition metal oxide, the cobalt-rich material includes a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than the molar content of Co in the matrix material. The coating material includes an electrolyte salt material.

[0122] The matrix material and cobalt source material are mixed and subjected to a first heating treatment in an oxygen-containing atmosphere. Through the diffusion of Co on the surface of the matrix material, a cobalt-rich material can be formed in situ at the diffusion sites. This cobalt-rich material has no interface with the matrix material and exhibits better affinity and structural compatibility, thereby improving the overall structural stability of the cathode active material. Furthermore, through the diffusion of Co on the surface of the matrix material, the entire surface of the matrix material can be coated with the cobalt-rich material in situ.

[0123] The coating material includes electrolyte salt material, whose elastic modulus is much smaller than that of the matrix material, thus enabling a larger coating area and further reducing side reactions between the matrix material and the sulfide solid electrolyte material.

[0124] Therefore, the positive electrode active material prepared by the preparation method of this disclosure has good high-temperature stability. As a result, the high-temperature stability between the positive electrode active material and the sulfide solid electrolyte material is good. When applied to solid-state battery cells, it can reduce the capacity decay rate of solid-state battery cells at high temperatures and improve the high-temperature cycle performance of solid-state battery cells.

[0125] In some embodiments, the temperature of the first heating treatment can be 500℃-800℃, for example, it can be 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, 720℃, 740℃, 760℃, 780℃, 800℃, or any range of the above values.

[0126] The temperature of the first heat treatment is within the above range, which allows Co to diffuse better on the surface of the matrix material and enables in-situ coating of the entire surface of the matrix material with cobalt-rich material.

[0127] In some embodiments, the duration of the first heating treatment can be 0.5h-10h, for example, it can be 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, or any range of the above values.

[0128] The first heat treatment time is within the above range, which allows Co to diffuse better on the surface of the matrix material and enables in-situ coating of the entire surface of the matrix material with cobalt-rich material.

[0129] In some embodiments, the temperature of the second heating treatment can be 300℃-400℃, for example, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, or any range of the above values.

[0130] In some embodiments, the duration of the second heating treatment can be 0.5h-5h, for example, 0.5h, 1h, 2h, 3h, 4h, 5h, or any range of the above values.

[0131] In some embodiments, the volume fraction of oxygen in the oxygen-containing atmosphere can be 50%-100%. For example, the oxygen-containing atmosphere can be oxygen gas or a mixture of oxygen gas and an inert gas. The inert gas can be one or more of nitrogen, argon, and helium, including but not limited to.

[0132] In some embodiments, the cobalt source material may include one or both of cobalt hydroxide and cobalt oxide.

[0133] In some embodiments, based on the total mass of the matrix material and the cobalt source material being 100%, the mass fraction of the cobalt source material can be 0.1%-3%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, or any range of the above values.

[0134] By adjusting the amount of cobalt source material, the thickness range of cobalt-rich materials can be adjusted, and elemental cobalt particles and / or cobalt oxide particles can be formed on the surface of Co-containing transition metal oxides.

[0135] In some embodiments, the matrix material and the cobalt source material can be mixed by dry mixing or wet mixing.

[0136] In some embodiments, the intermediate material and the coating material can be mixed by dry mixing or wet mixing.

[0137] This disclosure also provides a solid-state battery cell, which includes a negative electrode, a solid electrolyte membrane, and a positive electrode provided in this disclosure, wherein the solid electrolyte membrane is located between the negative electrode and the positive electrode.

[0138] [Negative electrode plate]

[0139] Negative electrode sheets can be prepared using either dry or wet processes.

[0140] In some embodiments, the negative electrode may include one or more of lithium, lithium alloy, natural graphite, artificial graphite, mesophase micro carbon spheres, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and metal oxides.

[0141] Optionally, the mass fraction of lithium in the lithium alloy can be above 90%.

[0142] Optionally, other elements in the lithium alloy may include, but are not limited to, one or more of In, Mg, Al, Zn, Sn, Ag, Au, Ga, Pt, and Fe.

[0143] Alternatively, the lithium alloy may include, but is not limited to, InLi alloy, Li-Mg alloy, Li-Al alloy, Li-Zn alloy, Li-Fe alloy, etc.

[0144] Optionally, the silicon-based material may include, but is not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.

[0145] Optionally, the tin-based material may include, but is not limited to, one or more of elemental tin, tin oxide, and tin alloy materials.

[0146] Optionally, the metal oxide may be one or more of TiO2, MoO2, In2O3, Al2O3, Cu2O, VO2, Ga2O3, Sb2O5, and Bi2O5.

[0147] In some embodiments, the negative electrode sheet may further include a negative electrode binder, which may include, but is not limited to, one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), carboxymethyl chitosan (CMCS), methyl vinyl silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), thermoplastic styrene-butadiene rubber (SBS), isoprene rubber, cis-butadiene rubber (BR), ethyl cellulose, fluororubber, and acrylate rubber.

[0148] In some embodiments, the negative electrode sheet may or may not include a negative electrode conductive agent.

[0149] Optionally, the negative electrode conductive agent may be one or more of the following, including but not limited to conductive graphite (such as KS-6, SFG-6), superconducting carbon, acetylene black, carbon black (such as SP), Ketjen black (such as ECP), carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0150] In some embodiments, the negative electrode may or may not include a solid electrolyte material. Optionally, the solid electrolyte material may include, but is not limited to, one or more of sulfide solid electrolyte materials, halide solid electrolyte materials, and oxide solid electrolyte materials.

[0151] The types of sulfide solid electrolyte materials can be found in the section on sulfide solid electrolyte materials for positive electrodes above, and will not be repeated here.

[0152] Optionally, the halide solid electrolyte material may include one or more of Li3YCl6, Li3YBr6, Li3ErCl6, Li3InCl6, and Li3InBr6.

[0153] Optionally, the oxide solid electrolyte material may include one or more of the following: perovskite structure oxide solid electrolyte material, garnet structure oxide solid electrolyte material, NASICON structure oxide solid electrolyte material, and LISICON structure oxide solid electrolyte material.

[0154] In some embodiments, the negative electrode can be a metal sheet, such as a lithium sheet or a lithium alloy sheet.

[0155] The negative electrode may or may not include a negative current collector.

[0156] In some embodiments, the negative electrode sheet may include a negative current collector and a lithium-based metal layer located on at least one surface of the negative current collector. The negative current collector has two surfaces opposite each other in its thickness direction, and the lithium-based metal layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0157] In some embodiments, the lithium-based metal layer may be metallic lithium or a lithium alloy.

[0158] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer located on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material. The negative electrode current collector has two surfaces opposite 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.

[0159] In some embodiments, the negative electrode active material may include, but is not limited to, one or more of natural graphite, artificial graphite, mesophase micro carbon spheres, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and metal oxides.

[0160] In some embodiments, the negative electrode film layer further includes a negative electrode binder, which may include, but is not limited to, one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), carboxymethyl chitosan (CMCS), methyl vinyl silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), thermoplastic styrene-butadiene rubber (SBS), isoprene rubber, cis-butadiene rubber (BR), ethyl cellulose, fluororubber, and acrylate rubber.

[0161] In some embodiments, the negative electrode film layer may or may not include a negative electrode conductive agent.

[0162] Optionally, the negative electrode conductive agent may be one or more of the following, including but not limited to conductive graphite (such as KS-6, SFG-6), superconducting carbon, acetylene black, carbon black (such as SP), Ketjen black (such as ECP), carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0163] In some embodiments, the negative electrode film layer may or may not include a solid electrolyte material. Optionally, the solid electrolyte material may include, but is not limited to, one or more of sulfide solid electrolyte materials, halide solid electrolyte materials, and oxide solid electrolyte materials.

[0164] The types of sulfide solid electrolyte materials can be found in the section on sulfide solid electrolyte materials for positive electrodes above, and will not be repeated here.

[0165] Optionally, the halide solid electrolyte material may include one or more of Li3YCl6, Li3YBr6, Li3ErCl6, Li3InCl6, and Li3InBr6.

[0166] Optionally, the oxide solid electrolyte material may include one or more of the following: perovskite structure oxide solid electrolyte material, garnet structure oxide solid electrolyte material, NASICON structure oxide solid electrolyte material, and LISICON structure oxide solid electrolyte material.

[0167] In some embodiments, the negative electrode current collector can be a metal foil, a three-dimensional porous current collector, or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil. Examples of three-dimensional porous current collectors include copper mesh, nickel mesh, aluminum mesh, copper foam, nickel foam, and aluminum foam. The composite current collector can include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer material substrates include, but are not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0168] [Solid electrolyte membrane]

[0169] Solid electrolyte membranes can be prepared by dry processes or wet processes.

[0170] In some embodiments, the solid electrolyte membrane may include a solid electrolyte material. Optionally, the solid electrolyte material may include, but is not limited to, one or more of sulfide solid electrolyte materials, halide solid electrolyte materials, and oxide solid electrolyte materials.

[0171] The types of sulfide solid electrolyte materials can be found in the section on sulfide solid electrolyte materials for positive electrodes above, and will not be repeated here.

[0172] Optionally, the halide solid electrolyte material may include one or more of Li3YCl6, Li3YBr6, Li3ErCl6, Li3InCl6, and Li3InBr6.

[0173] Optionally, the oxide solid electrolyte material may include one or more of the following: perovskite structure oxide solid electrolyte material, garnet structure oxide solid electrolyte material, NASICON structure oxide solid electrolyte material, and LISICON structure oxide solid electrolyte material.

[0174] In some embodiments, the solid electrolyte membrane may further include an adhesive. Optionally, the adhesive may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, water-soluble unsaturated resin SR-1B, methyl vinyl silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), styrene-butadiene rubber (SBR), thermoplastic styrene-butadiene rubber (SBS), isoprene rubber, butadiene rubber (BR), ethyl cellulose, polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), fluororubber, and acrylate rubber.

[0175] The methods for preparing solid-state battery cells are well known. For example, the assembly methods of solid-state battery cells include, but are not limited to, coin cells, mold cells, hard-case cells, and pouch cells.

[0176] Example

[0177] The following embodiments describe the disclosure of this disclosure in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0178] Example 1

[0179] Preparation of positive electrode active materials

[0180] Weigh LiNi according to a mass ratio of 99.5:0.5 0.8 Co 0.1 Mn 0.1O2 (abbreviated as NCM811) powder and Co(OH)2 powder are mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 600℃ for 1 hour in an oxygen atmosphere to obtain an intermediate material. The intermediate material powder and LiPO2F2 (abbreviated as LPF) powder are weighed at a mass ratio of 99:1 and mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 320℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material. The positive electrode active material includes the matrix material NCM811, a cobalt-rich material (i.e., Co-doped cobalt-rich NCM811) on the surface of NCM811, and a coating material LiPO2F2 on the surface of the cobalt-rich material. The thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm.

[0181] Preparation of positive electrode

[0182] The prepared positive electrode active material, sulfide solid electrolyte material Li6PS5Cl, positive electrode conductive agent vapor-grown carbon fiber (VGCF), and positive electrode binder polytetrafluoroethylene (PTFE) were mixed evenly in a double planetary mixer at a solid content mass ratio of 85:12:2:1. The mixed material was then heated and pressurized in an internal mixer to form a clump, which was then hot-rolled at 80°C to form a self-supporting electrode sheet. Finally, the electrode sheet was hot-rolled and combined with the positive electrode current collector aluminum foil to obtain the positive electrode sheet. The thickness of the positive electrode sheet was 100 μm.

[0183] Preparation of solid-state battery cells

[0184] Weigh 100 mg of sulfide solid electrolyte material Li6PS5Cl, add it to the battery mold, pressurize it to obtain an electrolyte sheet, then place the positive electrode sheet on one side of the electrolyte sheet, add InLi alloy on the other side as the negative electrode, pressurize it at 500 MPa for 5 min, and assemble it to obtain a solid battery cell.

[0185] Example 2

[0186] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0187] Preparation of positive electrode active materials

[0188] Weigh LiNi according to a mass ratio of 98.5:1.5 0.8 Co 0.1 Mn 0.1O2 (abbreviated as NCM811) powder and Co(OH)2 powder are mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 600℃ for 1 hour in an oxygen atmosphere to obtain an intermediate material. The intermediate material powder and LiPO2F2 (abbreviated as LPF) powder are weighed at a mass ratio of 99:1 and mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 320℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material. The positive electrode active material includes the matrix material NCM811, a cobalt-rich material (i.e., Co-doped cobalt-rich NCM811) on the surface of NCM811, and a coating material LiPO2F2 on the surface of the cobalt-rich material. The thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm.

[0189] Example 3

[0190] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0191] Preparation of positive electrode active materials

[0192] Weigh LiNi according to a mass ratio of 97:3. 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811) powder and Co(OH)2 powder are mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 600℃ for 1 hour in an oxygen atmosphere to obtain an intermediate material. The intermediate material powder and LiPO2F2 (abbreviated as LPF) powder are weighed at a mass ratio of 99:1 and mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 320℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material. The positive electrode active material includes the matrix material NCM811, a cobalt-rich material (i.e., Co-doped cobalt-rich NCM811) on the surface of NCM811, and a coating material LiPO2F2 on the surface of the cobalt-rich material. The thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm.

[0193] Example 4

[0194] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0195] Preparation of positive electrode active materials

[0196] Weigh LiNi according to a mass ratio of 99.5:0.5 0.8 Co 0.1 Mn 0.1O2 (abbreviated as NCM811) powder and Co(OH)2 powder are mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 600℃ for 1 hour in an oxygen atmosphere to obtain an intermediate material. The intermediate material powder and LiPO2F2 (abbreviated as LPF) powder are weighed at a mass ratio of 97:3 and mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 320℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material. The positive electrode active material includes the matrix material NCM811, a cobalt-rich material (i.e., Co-doped cobalt-rich NCM811) on the surface of NCM811, and a coating material LiPO2F2 on the surface of the cobalt-rich material. The thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm.

[0197] Example 5

[0198] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0199] Preparation of positive electrode active materials

[0200] Weigh LiNi according to a mass ratio of 99.5:0.5 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811) powder and Co(OH)2 powder are mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 600℃ for 1 hour in an oxygen atmosphere to obtain an intermediate material. The intermediate material powder and LiPO2F2 (abbreviated as LPF) powder are weighed at a mass ratio of 99.9:0.1 and mixed uniformly using a dry coating equipment. The uniformly mixed material is then heat-treated at 320℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material. The positive electrode active material includes the matrix material NCM811, a cobalt-rich material (i.e., Co-doped cobalt-rich NCM811) on the surface of NCM811, and a coating material LiPO2F2 on the surface of the cobalt-rich material. The thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm.

[0201] Example 6

[0202] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0203] Preparation of positive electrode active materials

[0204] Weigh LiNi according to a mass ratio of 99.5:0.5 0.8 Co 0.1 Mn 0.1O2 (abbreviated as NCM811) powder and Co(OH)2 powder were mixed uniformly using a dry coating equipment. The uniformly mixed material was then heat-treated at 600℃ for 1 hour in an oxygen atmosphere to obtain an intermediate material. The intermediate material powder and lithium difluorooxalate borate (abbreviated as LiDFOB) powder were weighed at a mass ratio of 99:1 and mixed uniformly using a dry coating equipment. The uniformly mixed material was then heat-treated at 320℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material. The positive electrode active material includes the matrix material NCM811, a cobalt-rich material (i.e., Co-doped cobalt-rich NCM811) on the surface of NCM811, and a coating material LiDFOB on the surface of the cobalt-rich material. The thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm.

[0205] Comparative Example 1

[0206] Preparation of positive electrode

[0207] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), sulfide solid electrolyte material Li6PS5Cl, positive electrode conductive agent vapor-grown carbon fiber (VGCF), and positive electrode binder polytetrafluoroethylene (PTFE) are mixed evenly in a double planetary mixer at a solid content mass ratio of 85:12:2:1. The uniformly mixed material is then heated and pressurized in an internal mixer to form a clump, which is then hot-rolled at 80°C to form a self-supporting electrode sheet. Finally, the electrode sheet is hot-rolled and combined with the positive electrode current collector aluminum foil to obtain the positive electrode sheet. The thickness of the positive electrode sheet is 100μm.

[0208] Preparation of solid-state battery cells

[0209] Weigh 100 mg of sulfide solid electrolyte material Li6PS5Cl, add it to the battery mold, pressurize it to obtain an electrolyte sheet, then place the positive electrode sheet on one side of the electrolyte sheet, add InLi alloy on the other side as the negative electrode, pressurize it at 500 MPa for 5 min, and assemble it to obtain a solid battery cell.

[0210] Comparative Example 2

[0211] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0212] Preparation of positive electrode active materials

[0213] Weigh LiNi according to a mass ratio of 99.5:0.5 0.8 Co 0.1 Mn 0.1O2 (abbreviated as NCM811) powder and Co(OH)2 powder are mixed evenly using a dry coating equipment; the evenly mixed material is heat-treated at 600℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material.

[0214] Comparative Example 3

[0215] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0216] Preparation of positive electrode active materials

[0217] Weigh LiNi according to a mass ratio of 99.5:0.5 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811) powder and Li2ZrO3 powder were mixed evenly using a dry coating equipment; the evenly mixed material was heat-treated at 400℃ for 1 hour in an oxygen atmosphere to obtain the positive electrode active material.

[0218] Performance testing

[0219] (1) First-round Coulomb efficiency test

[0220] At 60°C, solid-state battery cells were charged to 4.3V (vs. Li) at a current density of 0.1C. + / Li), let stand for 10 minutes, then discharge at a current density of 0.1C to 2.8V (vs. Li). + / Li), to obtain the specific capacity of the first charge and the specific capacity of the first discharge.

[0221] First-cycle coulombic efficiency (%) = First-cycle discharge specific capacity / First-cycle charge specific capacity × 100%.

[0222] (2) Cyclic performance test

[0223] At 60°C, the solid-state battery cells were first charged to 4.3V (vs. Li) at a current density of 0.1C. + / Li), let stand for 10 minutes, then discharge at a current density of 0.1C to 2.8V (vs. Li). + / Li), cycle charge and discharge 3 times; then charge the solid-state battery cell to 4.3V at a current density of 0.33C (vs. Li). + / Li), let stand for 10 minutes, then discharge at a current density of 0.33C to 2.8V (vs. Li). + / Li), the discharge specific capacity at this time is recorded as C1. The solid-state battery cell is cycled for 200 times at a current density of 0.33C, and the discharge capacity at this time is recorded as C2.

[0224] Solid-state battery cell capacity retention rate after 200 cycles = C2 / C1 × 100%.

[0225] Table 1

[0226] The test results above show that the positive electrode active material and the sulfide solid electrolyte material of the positive electrode sheet disclosed in this invention have good high-temperature stability, which can reduce the capacity decay rate of solid battery cells at high temperatures and improve the high-temperature cycle performance of solid battery cells.

[0227] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this disclosure are included within the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included within the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A positive electrode plate, wherein, The positive electrode sheet includes a positive electrode active material and a sulfide solid electrolyte material. The positive electrode active material includes a matrix material, a cobalt-rich material on the surface of the matrix material, and a coating material on at least a portion of the surface of the cobalt-rich material. The matrix material includes a transition metal oxide, the cobalt-rich material includes a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than the molar content of Co in the matrix material. The coating material includes an electrolyte salt material.

2. The positive electrode according to claim 1, wherein, The coating material includes fluorinated electrolyte salt materials.

3. The positive electrode according to any one of claims 1-2, wherein, The coating material includes one or more of Li2PO2F2, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

4. The positive electrode according to any one of claims 1-3, wherein, Based on the total mass of the positive electrode active material being 100%, the mass fraction of the coating material is 0.1%-3%.

5. The positive electrode according to any one of claims 1-4, wherein, The coating material is located on 90% to 100% of the surface of the cobalt-rich material.

6. The positive electrode according to any one of claims 1-5, wherein, The thickness of the cobalt-rich material ranges from 0.5 nm to 50 nm.

7. The positive electrode according to any one of claims 1-6, wherein, The matrix material includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-rich manganese-based materials; and / or, The cobalt-rich material includes one or more of the following: cobalt-rich lithium nickel cobalt manganese oxide, cobalt-rich lithium nickel cobalt aluminum oxide, and cobalt-rich lithium manganese-based materials.

8. The positive electrode according to any one of claims 1-7, wherein, The matrix material includes a Ni-containing transition metal oxide, and the cobalt-rich material includes a Ni- and Co-containing transition metal oxide, wherein the molar content of Ni in the cobalt-rich material is less than the molar content of Ni in the matrix material.

9. The positive electrode according to any one of claims 1-8, wherein, The cobalt-rich material is located on 100% of the surface of the substrate material; and / or, there is no interface between the cobalt-rich material and the substrate material.

10. The positive electrode according to any one of claims 1-9, wherein, The positive electrode active material also includes metal particles located between the cobalt-rich material and the coating material, wherein the metal particles include one or more of elemental cobalt particles and cobalt oxide particles.

11. The positive electrode according to any one of claims 1-10, wherein, The average particle size of the positive electrode active material is 3μm-10μm; and / or, The average particle size of the sulfide solid electrolyte material is 1 nm-20 μm; and / or, The mass ratio of the positive electrode active material to the sulfide solid electrolyte material is 99:1 to 70:

30.

12. The positive electrode according to any one of claims 1-11, wherein, The positive electrode sheet also includes a positive electrode conductive agent and / or a positive electrode binder.

13. The positive electrode according to any one of claims 1-12, wherein, The positive electrode sheet also includes a positive electrode current collector, and the positive electrode active material and the sulfide solid electrolyte material are located on at least one surface of the positive electrode current collector.

14. A solid-state battery cell, comprising a negative electrode, a solid electrolyte membrane, and a positive electrode as described in any one of claims 1-13, wherein the solid electrolyte membrane is located between the negative electrode and the positive electrode.

15. The solid-state battery cell according to claim 14, wherein, The negative electrode sheet comprises one or more of lithium, lithium alloy, natural graphite, artificial graphite, mesophase microcarbon spheres, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and metal oxides; and / or, The solid electrolyte membrane includes one or more of sulfide solid electrolyte materials, halide solid electrolyte materials, and oxide solid electrolyte materials.

16. A battery device comprising a plurality of solid-state battery cells as described in any one of claims 14-15.

17. An electrical device comprising a solid-state battery cell as described in any one of claims 14-15 or a battery device as described in claim 16.

18. A positive electrode active material, wherein, The positive electrode active material includes a matrix material, a cobalt-rich material located on the surface of the matrix material, and a coating material located on at least a portion of the surface of the cobalt-rich material; the matrix material includes a transition metal oxide, the cobalt-rich material includes a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than the molar content of Co in the matrix material; the coating material includes an electrolyte salt material.

19. A method for preparing a positive electrode active material, comprising the following steps: A matrix material, a cobalt source material, and a coating material are provided, wherein the matrix material includes a transition metal oxide, and the coating material includes an electrolyte salt material; The matrix material and the cobalt source material are mixed and subjected to a first heat treatment in an oxygen-containing atmosphere to obtain an intermediate material; The obtained intermediate material and the coating material are mixed and subjected to a second heat treatment in an oxygen-containing atmosphere to obtain the positive electrode active material, wherein... The positive electrode active material includes a matrix material, a cobalt-rich material on the surface of the matrix material, and a coating material on at least a portion of the surface of the cobalt-rich material. The matrix material includes a transition metal oxide, the cobalt-rich material includes a Co-containing transition metal oxide, and the molar content of Co in the cobalt-rich material is greater than the molar content of Co in the matrix material. The coating material includes an electrolyte salt material.

20. The preparation method according to claim 19, wherein, The temperature of the first heat treatment is 500℃-800℃; and / or, The duration of the first heat treatment is 0.5h-10h; and / or, The temperature of the second heat treatment is 300℃-400℃; and / or, The second heat treatment lasts for 0.5 h to 5 h; and / or, The cobalt source material includes one or both of cobalt hydroxide and cobalt oxide.

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