Positive electrode plate, solid-state battery monomer, battery device, power utilization device, positive electrode active material and preparation method of positive electrode active material

Abstract

The invention provides a positive plate, a solid-state battery monomer, a battery device, a power utilization device, a positive active material and a preparation method thereof. The positive plate comprises a positive active material and a sulfide solid electrolyte material; the positive active material comprises a base material, a first coating material positioned on at least part of the surface of the base material and a second coating material positioned on the surfaces of the first coating material and the base material; the first coating material comprises LZO; the second coating material comprises a solid electrolyte material, and the solid electrolyte material comprises one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide or lithium niobium phosphorus oxide. The positive plate is applied to the solid-state battery monomer and can improve the cycle performance of the battery.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically 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

[0002] With the rapid development of the electric vehicle industry and the widespread application of large-scale energy storage systems, the market demand for battery energy density continues to rise. Against this backdrop, ultra-high nickel layered oxides (chemical formula LiNi) with a nickel content ≥90% are in high demand. b Co c Mn d O2 (where b≥0.9) cathode materials have become a research hotspot in the field of electrochemical energy storage due to their significant advantages of high specific capacity and high energy density, and are considered to be one of the core cathode materials for the next generation of high energy density batteries.

[0003] However, when applying ultra-high nickel layered oxide cathode materials to sulfide all-solid-state batteries, two major challenges urgently need to be addressed, severely restricting the battery's cycle stability and safety performance:

[0004] Firstly, there is the issue of interfacial side reactions. The surface of ultra-high nickel materials exhibits extremely high chemical reactivity. During battery charging and discharging, its surface will react with sulfide electrolytes (such as Li₂). 10 GeP2S 12 In typical sulfide electrolyte systems, a violent and irreversible chemical reaction occurs. This reaction generates high-resistivity interfacial products such as CoS and NiS, which accumulate at the cathode / electrolyte interface to form a high-resistivity interfacial layer. This interfacial layer not only significantly increases the battery's interfacial impedance, hindering ion transport, but also continuously consumes active materials and electrolytes, ultimately leading to rapid capacity decay.

[0005] Secondly, there is the issue of structural stability. During charge-discharge cycles, the repeated insertion and extraction of lithium ions in ultra-high nickel layered oxides cause drastic volume expansion and contraction of the crystal lattice, leading to lattice distortion and stress concentration. With increasing cycle count, this lattice evolution and stress accumulation result in microcracks within the cathode material particles. These microcracks not only disrupt the material's integrity and reduce its conductivity but also further exacerbate electrolyte penetration into the material, promoting wider-ranging interfacial side reactions and creating a vicious cycle of "structural damage - intensified side reactions," severely impacting the battery's long-term cycle performance.

[0006] To address the aforementioned issues, various surface coating modification strategies have been proposed in the prior art, such as using single-layer or double-layer coatings (e.g., zirconium oxide (LZO) coating materials) to improve the interfacial stability of ultra-high nickel cathode materials. However, these existing technical solutions still have the following significant limitations:

[0007] Insufficient coating uniformity. Existing technologies mostly employ the traditional sol-gel method for coating, which is limited by reaction kinetics and mass transfer processes, making it difficult to achieve nanoscale uniform coating on the surface of ultra-high nickel materials. Especially for irregular areas such as defects and steps on the surface of ultra-high nickel materials, the coverage of the coating layer is extremely low, and even coating gaps may appear. This makes these "weak areas" preferential sites for interfacial side reactions, failing to fundamentally solve the interfacial stability problem.

[0008] The coating layer has a limited function. For example, the commonly used single-layer LZO coating layer in existing technology can only prevent direct contact between the cathode and the electrolyte to a certain extent, but it cannot simultaneously address the lattice mismatch between the core and shell and the electrolyte compatibility issue. On the one hand, the lattice parameters of LZO and ultra-high nickel materials differ significantly, which easily generates stress at the interface between the coating layer and the substrate, causing the coating layer to detach during cycling. On the other hand, the chemical stability of a single LZO coating layer for sulfide electrolytes still needs improvement, and slow interfacial reactions still occur after long-term cycling.

[0009] Ultra-high nickel systems exhibit poor compatibility. Existing coating technologies primarily target high-nickel material systems with nickel content below 90%. For ultra-high nickel material systems with Ni ≥ 90%, the surface activity is higher and the structural stability is worse, placing more stringent requirements on parameters such as coating thickness, stoichiometry, and crystal structure. However, existing technologies lack systematic optimization research on LZO coating parameters for ultra-high nickel materials with Ni ≥ 90%, resulting in coated materials failing to meet practical application requirements in key indicators such as cycle performance and rate capability.

[0010] In summary, existing surface coating technologies cannot simultaneously meet the requirements of atomic-level coating precision, multi-layer gradient functional synergy, and compatibility with ultra-high nickel systems for ultra-high nickel cathode materials in sulfide all-solid-state batteries. Therefore, there is an urgent need to develop a novel cathode material and its preparation method that combines atomic-level uniform coating, multi-layer gradient functional design, and compatibility with ultra-high nickel materials to overcome the current technical bottlenecks in ultra-high nickel sulfide all-solid-state batteries. Summary of the Invention

[0011] The purpose of this application is to overcome the shortcomings of existing ultra-high nickel cathode materials in sulfide all-solid-state batteries, such as severe interfacial side reactions, poor structural stability, insufficient coating uniformity, single function, and poor ultra-high nickel adaptability. This application provides a multi-layer gradient coated ultra-high nickel cathode material, its preparation method, and an all-solid-state battery. Through the synergistic design of the multi-layer coating structure, the material's interfacial stability and structural stability are improved simultaneously.

[0012] In a first aspect, this application provides a positive electrode sheet, the positive electrode sheet comprising a positive electrode active material and a sulfide solid electrolyte material, the positive electrode active material comprising a matrix material, a first coating material located on at least a portion of the surface of the matrix material, and a second coating material located on the surfaces of the first coating material and the matrix material, the first coating material comprising LZO, the second coating material comprising a solid electrolyte material, the solid electrolyte material comprising one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, or lithium niobium phosphorus oxide.

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

[0014] In some embodiments, the average particle size of the positive electrode active material is 3 μm-10 μm.

[0015] In some embodiments, the matrix material is composed of Li a Ni b Co c M d O e A f Where 0.8≤a≤1.2, 0.3≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes one or more of N, F, S and Cl.

[0016] In some embodiments, the matrix material in the positive electrode active material is composed of LiNi. b Co c Mn d O2, where b≥0.9, c+d=1-b; preferably, the matrix material in the positive electrode active material is composed of LiNi. 0.9 Co 0.05 Mn 0.05 O2, this composition enables the cathode material to have a high specific capacity.

[0017] In some embodiments, the particle size D of the matrix material 50The particle size is 3-5 μm; the small particle size design helps to improve the diffusion rate of lithium ions inside the material and ensure the rate performance of the battery.

[0018] In some embodiments, the first coating material comprises gLi2O-ZrO2, where g=1.2±0.1; this stoichiometric ratio can optimize the lithium-ion conductivity of the coating layer and avoid obstruction of ion transport.

[0019] In some embodiments, the thickness of the coating layer formed by the first coating material is 5-20 nm; the thickness is precisely controlled by an atomic layer deposition process to ensure coating uniformity while taking into account ion transport efficiency.

[0020] In some embodiments, the coating amount of the first coating material is 0.3-0.8 wt% based on the total mass of the cathode material as 100%. Within this range, the coating amount can balance the interfacial stability and the proportion of active material, avoiding capacity loss due to over-coating.

[0021] In some embodiments, the function of the first coating material is to alleviate the stress generated by the expansion and contraction of the material lattice during charging and discharging, and to block transition metal ions (Ni). 3+ Co 3+ The dissolution of the positive electrode and the physical isolation of the electrolyte suppress the interfacial side reactions between them.

[0022] In some embodiments, the mass fraction of the second coating material is 0.1%-3% based on the total mass of the positive electrode active material being 100%. A mass fraction of coating material within the above range can enable the positive electrode active material to possess high ionic conductivity and high specific capacity.

[0023] In some embodiments, the average particle size of the sulfide solid electrolyte material is 1 nm-20 μm.

[0024] 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.

[0025] In some embodiments, the positive electrode sheet further includes a positive electrode conductive agent and / or a positive electrode binder.

[0026] In some embodiments, the positive electrode sheet further includes a positive electrode current collector, wherein the positive electrode active material and the sulfide solid electrolyte material are located on at least one surface of the positive electrode current collector.

[0027] Secondly, this application provides a solid-state battery cell, including 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.

[0028] 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.

[0029] 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.

[0030] Thirdly, this application provides a battery device comprising a plurality of solid-state battery cells as described in the second aspect.

[0031] Fourthly, this application 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).

[0032] Fifthly, this application provides a positive electrode active material, which includes a matrix material, a first coating material located on at least a portion of the surface of the matrix material, and a second coating material located on the surfaces of the first coating material and the matrix material. The first coating material includes LZO, and the second coating material includes a solid electrolyte material, wherein the solid electrolyte material includes one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, or lithium niobium phosphorus oxide.

[0033] Sixthly, this application provides a method for preparing a positive electrode active material, comprising the following steps:

[0034] S1: Prepare a matrix material;

[0035] S2: A first coating layer is formed by coating the surface of the base material with a first coating material;

[0036] S3: A second coating material is coated onto the surface of the first coating layer to form a second coating layer;

[0037] The first coating material includes LZO, and the second coating material includes a solid electrolyte material, wherein the solid electrolyte material includes one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, or lithium niobium phosphorus oxide.

[0038] In some embodiments, the matrix material is composed of LiNi b Co c Mn dO2, where b≥0.9, c+d=1-b.

[0039] In some embodiments, the composition of the first coating material includes gLi2O-ZrO2, where g = 1.2 ± 0.1. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0041] Figure 1 This document shows schematic diagrams of solid-state battery cells provided in some embodiments of this application.

[0042] Figure 2 A schematic diagram of an electrical device provided in some embodiments of this application is shown.

[0043] The accompanying drawings are not necessarily drawn to scale.

[0044] Explanation of reference numerals in the attached figures:

[0045] 5. Solid-state battery cells. Detailed Implementation

[0046] 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 thorough understanding of this application by those skilled in the art and are not intended to limit the subject matter of the claims.

[0047] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a 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 included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 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 application, 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.

[0048] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0049] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0050] Unless otherwise specified, all steps in this 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 it may include steps (b) and (a) performed sequentially. For example, the method may also 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 it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0051] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0052] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0053] In the description of the embodiments of this application, 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" 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.

[0054] Unless otherwise stated, the test temperature for all parameters mentioned in this application is 25°C.

[0055] The solid-state battery cell mentioned in the embodiments of this application can independently perform charge and discharge functions. After discharge, it can be reactivated by charging to allow for continued use. The solid-state battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited in this regard. Figure 1 This is an example of a rectangular solid-state battery cell 5.

[0056] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple solid-state battery cells, which are connected in series, parallel, or mixed connections via busbars.

[0057] In some embodiments, a battery cell assembly is typically formed by arranging multiple solid-state battery cells.

[0058] As an example, a battery cell assembly can be a battery module, which consists of multiple solid-state battery cells arranged and fixed 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.

[0059] 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.

[0060] 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.

[0061] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple solid-state battery cells to the housing.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use solid-state battery cells and 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.

[0066] Figure 2 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0067] The solid-state battery cell provided in the embodiments of this application includes an electrode assembly and an outer packaging, the outer packaging being used to encapsulate the electrode assembly. The outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0068] 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.

[0069] In particular, when ultra-high nickel layered oxide cathode materials are applied to sulfide all-solid-state batteries, two major challenges urgently need to be addressed, which severely restrict the cycle stability and safety performance of the batteries:

[0070] Firstly, there is the issue of interfacial side reactions. The surface of ultra-high nickel materials exhibits extremely high chemical reactivity. During battery charging and discharging, its surface will react with sulfide electrolytes (such as Li₂). 10 GeP2S 12 In typical sulfide electrolyte systems, a violent and irreversible chemical reaction occurs. This reaction generates high-resistivity interfacial products such as CoS and NiS, which accumulate at the cathode / electrolyte interface to form a high-resistivity interfacial layer. This interfacial layer not only significantly increases the battery's interfacial impedance, hindering ion transport, but also continuously consumes active materials and electrolytes, ultimately leading to rapid capacity decay.

[0071] Secondly, there is the issue of structural stability. During charge-discharge cycles, the repeated insertion and extraction of lithium ions in ultra-high nickel layered oxides cause drastic volume expansion and contraction of the crystal lattice, leading to lattice distortion and stress concentration. With increasing cycle count, this lattice evolution and stress accumulation result in microcracks within the cathode material particles. These microcracks not only disrupt the material's integrity and reduce its conductivity but also further exacerbate electrolyte penetration into the material, promoting wider-ranging interfacial side reactions and creating a vicious cycle of "structural damage - intensified side reactions," severely impacting the battery's long-term cycle performance.

[0072] To address the aforementioned issues, various surface coating modification strategies have been proposed in the prior art, such as using single-layer or double-layer coatings (e.g., zirconium oxide (LZO) coating materials) to improve the interfacial stability of ultra-high nickel cathode materials. However, these existing technical solutions still have the following significant limitations:

[0073] Insufficient coating uniformity. Existing technologies mostly employ the traditional sol-gel method for coating, which is limited by reaction kinetics and mass transfer processes, making it difficult to achieve nanoscale uniform coating on the surface of ultra-high nickel materials. Especially for irregular areas such as defects and steps on the surface of ultra-high nickel materials, the coverage of the coating layer is extremely low, and even coating gaps may appear. This makes these "weak areas" preferential sites for interfacial side reactions, failing to fundamentally solve the interfacial stability problem.

[0074] The coating layer has a limited function. For example, the commonly used single-layer LZO coating layer in existing technology can only prevent direct contact between the cathode and the electrolyte to a certain extent, but it cannot simultaneously address the lattice mismatch between the core and shell and the electrolyte compatibility issue. On the one hand, the lattice parameters of LZO and ultra-high nickel materials differ significantly, which easily generates stress at the interface between the coating layer and the substrate, causing the coating layer to detach during cycling. On the other hand, the chemical stability of a single LZO coating layer for sulfide electrolytes still needs improvement, and slow interfacial reactions still occur after long-term cycling.

[0075] Ultra-high nickel systems exhibit poor compatibility. Existing coating technologies primarily target high-nickel material systems with nickel content below 90%. For ultra-high nickel material systems with Ni ≥ 90%, the surface activity is higher and the structural stability is worse, placing more stringent requirements on parameters such as coating thickness, stoichiometry, and crystal structure. However, existing technologies lack systematic optimization research on LZO coating parameters for ultra-high nickel materials with Ni ≥ 90%, resulting in coated materials failing to meet practical application requirements in key indicators such as cycle performance and rate capability.

[0076] In summary, existing surface coating technologies cannot simultaneously meet the requirements of atomic-level coating precision, multi-layer gradient functional synergy, and compatibility with ultra-high nickel systems for ultra-high nickel cathode materials in sulfide all-solid-state batteries. Therefore, there is an urgent need to develop a novel cathode material and its preparation method that combines atomic-level uniform coating, multi-layer gradient functional design, and compatibility with ultra-high nickel materials to overcome the current technical bottlenecks in ultra-high nickel sulfide all-solid-state batteries.

[0077] Based on this, this application provides a positive electrode active material and a positive electrode sheet containing the same, which can be 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 cycle performance of the solid-state battery cell.

[0078] The positive electrode sheet of this application includes a positive electrode active material and a sulfide solid electrolyte material. The positive electrode active material includes a matrix material and a first coating material located on at least a portion of the surface of the matrix material, and a second coating material located on the surfaces of the first coating material and the matrix material. The first coating material includes LZO, and the second coating material includes a solid electrolyte material.

[0079] In some embodiments, the matrix material includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium cobalt oxide, and lithium-rich manganese-based materials.

[0080] In some embodiments, the average particle size of the positive electrode active material is 3 μm-10 μm.

[0081] In some embodiments, the matrix material may include materials of the general formula Li a Ni b Coc M d O e A f The material has the following properties: 0.8≤a≤1.2, 0.3≤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.

[0082] Alternatively, 0.5 ≤ b < 1, 0.6 ≤ b < 1, 0.8 ≤ b < 1, and 0.83 ≤ b < 1.

[0083] 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.

[0084] As an example, 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] Furthermore, the matrix material is composed of LiNi b Co c Mn d O2, where b ≥ 0.9, c + d = 1 - b. Furthermore, 0.9 ≤ b < 1, 0 < c < 0.1, 0 < d < 0.1, c + d = 1 - b. In some specific examples, the matrix material composition is LiNi. 0.9 Co 0.05 Mn 0.05 O2.

[0086] 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 application, the Li molar content refers to the initial state of the material, i.e., the state before material addition. 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 application is only a theoretical value. Lattice oxygen release causes changes in the O molar content, and the actual O molar content will also fluctuate.

[0087] In some embodiments, the particle size D of the matrix material 50 The particle size is 3-5 μm; the small particle size design helps to improve the diffusion rate of lithium ions inside the material and ensure the rate performance of the battery.

[0088] In some embodiments, the positive electrode active material may be monocrystalline or polycrystalline.

[0089] In some embodiments, the first coating material is composed of gLi2O-ZrO2, where g=1.2±0.1; this stoichiometric ratio can optimize the lithium-ion conductivity of the coating layer and avoid obstruction of ion transport.

[0090] In some embodiments, the thickness of the coating layer formed by the first coating material is 5-20 nm; the thickness is precisely controlled by an atomic layer deposition process to ensure coating uniformity while taking into account ion transport efficiency.

[0091] In some embodiments, the coating amount of the first coating material is 0.3-0.8 wt% based on the total mass of the cathode material as 100%. Within this range, the coating amount can balance the interfacial stability and the proportion of active material, avoiding capacity loss due to over-coating.

[0092] In some embodiments, the function of the first coating material is to alleviate the stress generated by the expansion and contraction of the material lattice during charging and discharging, and to block transition metal ions (Ni). 3+ Co 3+ The dissolution of the positive electrode and the physical isolation of the electrolyte suppress the interfacial side reactions between them.

[0093] In some embodiments, based on the total mass of the positive electrode active material as 100%, the mass fraction of the first 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.

[0094] 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.

[0095] Optionally, the mass fraction of the coating material can be 0.5%-3%, 0.5%-2.5%, 0.5%-2%, or 0.5%-1.5%.

[0096] 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.

[0097] In some embodiments, the second coating material includes one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, and lithium niobium phosphorus oxide.

[0098] In some embodiments, lithium germanium phosphorus oxides include Li2O-GeO2-P2O5 (LGPO), Li4GeO4-Li3PO4 (LGP), and Li 3.5 Ge 0.5 P 0.5 One or more of O4 (LGPO).

[0099] In some embodiments, lithium silicon phosphorus oxide includes Li2O-SiO2-P2O5 (LSPO), Li 3.4 Si 0.4 P 0.6 One or two of O4 (LSPO).

[0100] In some embodiments, lithium aluminum phosphate oxides include Li₂O-Al₂O₃-P₂O₅ (LAPO), LiAlPO₄ (LAP), and Li 1- x Al x Ge 2-x One or more of (PO4)3 (LAGP).

[0101] In some embodiments, lithium boron phosphorus oxide includes one or two of Li2O-B2O3-P2O5 (LBPO) and Li3BO3-Li3PO4 (LBP).

[0102] In some embodiments, lithium titanium phosphate oxide includes one or both of Li2O-TiO2-P2O5 (LTPO) and LiTi2(PO4)3 (LTP).

[0103] In some embodiments, the lithium niobium phosphorus oxide system includes one or both of Li2O-Nb2O5-P2O5 (LNPO) and Li3NbO4-Li3PO4 (LNP).

[0104] LZO (cubic phase, a = 5.14 Å) and sulfide electrolytes (such as Li) 10 GeP2S 12 The tetragonal phase has a high lattice mismatch rate (>10%), which easily generates interfacial stress. Using a second coating material as an intermediate layer, whose lattice constant is between that of LZO and sulfide electrolytes, can reduce interfacial defects and lower the lithium-ion migration barrier.

[0105] Zr in LZO 4+ It readily reacts with sulfur in sulfide electrolytes. 2- The reaction produces ZrS2, leading to an increase in interfacial impedance. Furthermore, the phosphorus (P) element in the second coating material preferentially reacts with sulfur (S). 2- Stable PS bonds (such as P2S5) are formed to protect LZO from corrosion. The second coating material acts as a "sacrificial layer" to consume active sulfur, protecting both LZO and the cathode.

[0106] The lithium-ion conductivity of LZO (10 -6 S / cm) is lower than that of sulfide electrolytes (10 -2 The high ionic conductivity (S / cm) leads to lithium ion accumulation at the interface. The second coating material, however, possesses high ionic conductivity, forming a gradient transport path of "LZO → second coating material → sulfide electrolyte," reducing interfacial polarization and improving rate performance.

[0107] In some embodiments, the mass fraction of the second 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 the above range can enable the positive electrode active material to possess high ionic conductivity and high specific capacity.

[0108] In some embodiments, based on the total mass of the positive electrode active material as 100%, the mass fraction of the second 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.

[0109] 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.

[0110] Optionally, the mass fraction of the coating material can be 0.5%-3%, 0.5%-2.5%, 0.5%-2%, or 0.5%-1.5%.

[0111] 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.

[0112] In some embodiments, the average particle size of the sulfide solid electrolyte material is 1 nm-20 μm.

[0113] 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.

[0114] In some embodiments, the positive electrode sheet further includes a positive electrode conductive agent and / or a positive electrode binder.

[0115] 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.

[0116] In some embodiments, the sulfide solid electrolyte material may include, but is not limited to, one or more of the following: silver-germanium sulfide type, LGPS type, lithium sulfide-phosphorus pentasulfide complex type sulfide solid electrolyte materials.

[0117] Optionally, the sulfide solid electrolyte material of the silver-germanium sulfide type may include Li 6±s P 1-j A j S 5±s- t B t X 1±s The material has the following properties: 0≤j<1, 0≤t<1, 0≤s<1, A includes one or more elements from Ge, Si, Sn and Sb, B includes one or more elements from O, Se and Te, and X includes one or more elements from Cl, Br, I and F.

[0118] Optionally, LGPS-type sulfide solid electrolyte materials may include those with the chemical formula Li 10±δ5 Ge 1-g G g P 2-q Q q S 12- w W wThe material, 0≤δ5<1, 0≤g≤1, 0≤q≤2, 0≤w<1, G includes one or both of the elements Si and Sn, Q includes Sb, and W includes one or more of the elements O, Se, Te, Cl, Br, I, and F.

[0119] Optionally, the sulfide solid electrolyte material of the lithium sulfide - phosphorus pentasulfide composite type may include a material with the chemical formula (100 - u - v)Li2SuP2S5vM m N n The material, 0 < u < 100, 0≤v<100, 0≤u + v<100, 0≤m<4, 0≤n<6, M includes one or more of the elements Li, B, Ge, Si, Sn, and Sb, and N includes one or more of the elements S, Se, Te, O, Cl, Br, I, and F.

[0120] In some embodiments, by way of example, the sulfide solid electrolyte material may include Li6PS5Cl, Li6PS5Br, Li 10 GeP2S 12 、Li3PS4、Li7P3S 11 and one or more of them.

[0121] In some embodiments, the average particle size of the sulfide solid electrolyte material may be 1 nm - 20 μm, and optionally 50 nm - 5 μm.

[0122] [[ID=​​​​​​​​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, 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.

[0126] 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).

[0127] The positive electrode may or may not include a positive current collector.

[0128] 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.

[0129] 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.

[0130] 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, 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.

[0131] In some embodiments, the positive electrode film layer 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).

[0132] 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.

[0133] Positive electrode sheets can be prepared using either a dry process or a wet process.

[0134] The average particle size can be tested as follows: Using a scanning electron microscope (SEM) according to JY / T010-1996, acquire an SEM image of the positive electrode sheet. Randomly select a test sample with dimensions of 50mm x 100mm on the positive electrode sheet. Randomly select multiple test areas (e.g., 5 areas) within the test sample, and read the particle size of each particle in each test area at a certain magnification (e.g., 500x or higher). Count the number and particle size values ​​of particles in each test area, and take the arithmetic mean of the particle sizes in all test areas as the average particle size. To ensure the accuracy of the test results, multiple test samples (e.g., 10 samples) can be used for the above test, and the average value of each test sample can be taken as the final test result. The testing instrument can be a ZEISS Sigma 300. It should be noted that when the particles are irregularly shaped, the distance between the two farthest points on the particle should be taken as the particle size.

[0135] This application also provides a method for preparing a positive electrode active material, which can prepare the above-mentioned positive electrode active material.

[0136] In some embodiments, the matrix material is synthesized as a precursor via co-precipitation, followed by lithiation and calcination. The precursor is in hydroxide form, and its synthesis involves reacting a mixed metal salt solution containing nickel, cobalt, and manganese with a precipitant solution under suitable conditions to generate a homogeneous precipitate, which is then separated, washed, and dried to obtain the precursor material. Subsequently, the precursor is mixed with a lithium source and calcined at high temperature in an oxygen-containing atmosphere to achieve lithiation and construct a layered crystal structure, thereby obtaining a nickel-rich layered oxide core.

[0137] In some embodiments, the first coating layer is formed using atomic layer deposition (ALD). This process employs alternating pulses of lithium-containing and metal-containing precursors to deposit a uniform and dense lithium-containing inorganic oxide film on the core surface. By controlling the number of deposition cycles, nanometer-scale precise control of the coating layer thickness can be achieved. The first coating layer exhibits good chemical stability and ionic conductivity, effectively suppressing side reactions between the core and the electrolyte, and improving the cycling and thermal stability of the material.

[0138] In some embodiments, the second coating layer is formed using a molecular layer deposition (MLD) process. This process employs a precursor containing lithium, phosphorus, and at least one metal element to construct a compatible layer with solid-state electrolyte properties on the surface of the first coating layer in the presence of an oxidant. The second coating layer possesses high ionic conductivity and interfacial stability, enabling the formation of good interfacial contact between the electrode and the electrolyte, reducing interfacial impedance, and improving the rate performance and cycle life of the battery.

[0139] In some implementations, the thicknesses of both the first and second coating layers are in the nanoscale range and can be adjusted by deposition process parameters to achieve performance optimization for different application scenarios.

[0140] In some embodiments, the preparation process of the composite cathode material includes the following steps:

[0141] (1) Provide a matrix material;

[0142] (2) A first coating layer is formed by coating the surface of the substrate material with a first coating material through an atomic layer deposition process;

[0143] (3) A second coating layer is formed by coating the surface of the first coating layer with a second coating material through a molecular layer deposition process.

[0144] In some embodiments, the matrix material is composed of LiNi. b Co c Mn d O2, where b ≥ 0.9, c + d = 1 - b. Furthermore, 0.9 ≤ b < 1, 0 < c < 0.1, 0 < d < 0.1, c + d = 1 - b. In some specific examples, the matrix material composition is LiNi. 0.9 Co 0.05 Mn 0.05 O2.

[0145] In some embodiments, the composition of the first coating material includes gLi2O-ZrO2, where g = 1.2 ± 0.1.

[0146] In some embodiments, the second coating material includes one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, and lithium niobium phosphorus oxide.

[0147] The composite cathode material provided in this application, through the synergistic design of the core and the double-layer nano-coating structure, takes into account high capacity, high stability and good interface compatibility, and is suitable for high energy density lithium-ion battery systems, showing good application prospects.

[0148] In some embodiments, the preparation process of the composite cathode material includes the following steps:

[0149] Step 1: Synthesis of matrix material

[0150] In some embodiments, a co-precipitation method is used to synthesize a hydroxide precursor of ultra-high nickel NCM core, specifically comprising: mixing a mixed solution of NiSO4, CoSO4, and MnSO4 with a mixed solution of NaOH / ammonia in a reactor; wherein the molar ratio of Ni:Co:Mn in the mixed solution is 90:5:5, and the total metal ion concentration is 2 mol / L; the NaOH concentration in the NaOH / ammonia mixed solution is 6 mol / L, and the ammonia concentration is 1 mol / L.

[0151] In some embodiments, the process parameters for the coprecipitation reaction are: pH = 11.5 ± 0.2, reaction temperature 50°C, stirring rate 500 rpm, and reaction time 12 h; after the reaction is completed, the hydroxide precursor is obtained by filtration, washing, and drying.

[0152] In some embodiments, the hydroxide precursor and LiOH·H2O are mixed uniformly at a ratio of Li:TM=1.05:1 (TM is the total molar number of Ni, Co and Mn), and calcined at 750°C for 10 h under an O2 atmosphere. After natural cooling, an ultra-high nickel NCM core is obtained. The calcination process can promote the full lithiation reaction and form a complete layered crystal structure.

[0153] Step 2: Atomic Layer Deposition (ALD) of LZO Coating

[0154] In some embodiments, LiOtBu (lithium tert-butoxide) is used as the lithium source, Zr(OtBu)4 (zirconium tert-butoxide) is used as the zirconium source, and N2 is used as the carrier gas and purge gas to deposit the LZO coating layer in an atomic layer deposition apparatus.

[0155] In some embodiments, the process parameters for ALD deposition are: deposition temperature 250℃, LiOtBu pulse time 0.1 s, Zr(OtBu)4 pulse time 0.2 s, and N2 purge time 10 s after each pulse; a 5-20 nm thick LZO coating layer is achieved by controlling the number of cycles (50-200 times).

[0156] In some embodiments, a quartz crystal microbalance (QCM) is used to monitor the film thickness in real time during the deposition process, with a monitoring accuracy of ±0.1 nm; this monitoring method can ensure precise control of the LZO coating thickness.

[0157] Step 3: Molecular layer deposition (MLD) of solid electrolyte compatible layer

[0158] In some embodiments, LGPO solid electrolyte compatible layers are deposited in a molecular layer deposition apparatus using LiOtBu, Ge(OEt)4 (tetraethoxygermanium), and PO(OEt)3 (triethyl phosphate) as precursors and H2O as an oxidant.

[0159] In some embodiments, the process parameters for MLD deposition are: deposition temperature 200℃, pulse sequence LiOtBu→Ge(OEt)4→PO(OEt)3→H2O, pulse duration for each precursor 0.3 s, and N2 purge time after pulse 8 s; LGPO layer coating with a thickness of 2-10 nm is achieved by controlling the number of cycles (20-50 times).

[0160] This application also provides a solid-state battery cell, which includes a negative electrode, a solid electrolyte membrane, and a positive electrode provided in this application, wherein the solid electrolyte membrane is located between the negative electrode and the positive electrode.

[0161] [Negative electrode plate]

[0162] Negative electrode sheets can be prepared using either dry or wet processes.

[0163] 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.

[0164] Optionally, the mass fraction of lithium in the lithium alloy can be above 90%.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] Optionally, the tin-based material may include, but is not limited to, one or more of elemental tin, tin oxide, and tin alloy materials.

[0169] Optionally, the metal oxide may be one or more of TiO2, MoO2, In2O3, Al2O3, Cu2O, VO2, Ga2O3, Sb2O5, and Bi2O5.

[0170] 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.

[0171] In some embodiments, the negative electrode sheet may or may not include a negative electrode conductive agent.

[0172] 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).

[0173] 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.

[0174] 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.

[0175] Optionally, the halide solid electrolyte material may include one or more of Li3YCl6, Li3YBr6, Li3ErCl6, Li3InCl6, and Li3InBr6.

[0176] 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.

[0177] In some embodiments, the negative electrode can be a metal sheet, such as a lithium sheet or a lithium alloy sheet.

[0178] The negative electrode may or may not include a negative current collector.

[0179] 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.

[0180] In some embodiments, the lithium-based metal layer may be metallic lithium or a lithium alloy.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] In some embodiments, the negative electrode film layer may or may not include a negative electrode conductive agent.

[0185] 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).

[0186] 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.

[0187] 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.

[0188] Optionally, the halide solid electrolyte material may include one or more of Li3YCl6, Li3YBr6, Li3ErCl6, Li3InCl6, and Li3InBr6.

[0189] 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.

[0190] 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.

[0191] [Solid electrolyte membrane]

[0192] Solid electrolyte membranes can be prepared by dry processes or wet processes.

[0193] 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.

[0194] 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.

[0195] Optionally, the halide solid electrolyte material may include one or more of Li3YCl6, Li3YBr6, Li3ErCl6, Li3InCl6, and Li3InBr6.

[0196] 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.

[0197] 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.

[0198] 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, molded cells, hard-case cells, and pouch cells.

[0199] Example

[0200] The following embodiments describe the disclosure of this application 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 the disclosure of this application. 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.

[0201] Example 1

[0202] Preparation of positive electrode active materials

[0203] Step 1: Synthesis of matrix material

[0204] A hydroxide precursor for ultra-high nickel NCM cores was synthesized by a co-precipitation method, specifically comprising: mixing a mixed solution of NiSO4, CoSO4, and MnSO4 with a mixed solution of NaOH / ammonia in a reactor; wherein the molar ratio of Ni:Co:Mn in the mixed solution is 90:5:5, and the total metal ion concentration is 2 mol / L; the NaOH / ammonia mixed solution has a NaOH concentration of 6 mol / L and an ammonia concentration of 1 mol / L.

[0205] The process parameters for the coprecipitation reaction were: pH = 11.5 ± 0.2, reaction temperature 50℃, stirring rate 500 rpm, and reaction time 12 h. After the reaction was completed, the hydroxide precursor was obtained by filtration, washing, and drying.

[0206] The hydroxide precursor and LiOH·H2O were mixed uniformly at a ratio of Li:TM=1.05:1 (TM is the total molar number of Ni, Co and Mn), and calcined at 750℃ for 10 h under O2 atmosphere. After natural cooling, ultra-high nickel NCM core was obtained. The calcination process can promote the full lithiation reaction and form a complete layered crystal structure.

[0207] Step 2: Atomic Layer Deposition (ALD) of LZO Coating

[0208] Using LiOtBu (lithium tert-butoxide) as the lithium source, Zr(OtBu)4 (zirconium tert-butoxide) as the zirconium source, and N2 as the carrier gas and purge gas, LZO coating was deposited in an atomic layer deposition apparatus.

[0209] The process parameters for ALD deposition were: deposition temperature 250℃, LiOtBu pulse time 0.1 s, Zr(OtBu)4 pulse time 0.2 s, and N2 purging time 10 s after each pulse.

[0210] Step 3: Molecular layer deposition (MLD) of solid electrolyte compatible layer

[0211] Using LiOtBu, Ge(OEt)4 (tetraethoxygermanium), and PO(OEt)3 (triethyl phosphate) as precursors and H2O as oxidant, an LGPO solid electrolyte compatible layer was deposited in a molecular layer deposition apparatus.

[0212] The process parameters for MLD deposition were as follows: deposition temperature 200℃, pulse sequence LiOtBu→Ge(OEt)4→PO(OEt)3→H2O, pulse duration for each precursor 0.3 s, and N2 purging time after pulse 8 s.

[0213] Preparation of positive electrode

[0214] 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.

[0215] Preparation of solid-state battery cells

[0216] 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.

[0217] Example 2

[0218] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0219] Li2O-SiO2-P2O5 (LSPO) was used as the second coating layer.

[0220] Example 3

[0221] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0222] Li2O-Al2O3-P2O5 (LAPO) was used as the second coating layer.

[0223] Example 4

[0224] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0225] Li2O-B2O3-P2O5 (LBPO) was used as the second coating layer.

[0226] Example 5

[0227] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0228] Li2O-TiO2-P2O5 (LTPO) was used as the second coating layer.

[0229] Example 6

[0230] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0231] Li2O-Nb2O5-P2O5 (LNPO) was used as the second coating layer.

[0232] Comparative Example 1

[0233] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0234] LGPO and LZO were not used for coating.

[0235] Comparative Example 2

[0236] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0237] LGPO was not used for encapsulation.

[0238] Performance testing

[0239] (1) First-lap Coulomb efficiency test

[0240] At 60°C, solid-state battery cells were charged to 4.3V at a current density of 0.1C (vs. Li). + / Li), let stand for 10 minutes, and then discharge to 2.8V at a current density of 0.1C (vs. Li). + / Li), to obtain the specific capacity of the first charge and the specific capacity of the first discharge.

[0241] First-cycle coulombic efficiency (%) = First-cycle discharge specific capacity / First-cycle charge specific capacity × 100%.

[0242] (2) Cyclic performance test

[0243] The solid-state battery cells were first charged to 4.3V at a current density of 0.1C (vs. Li). + / Li), let stand for 10 minutes, and then discharge to 2.8V at a current density of 0.1C (vs. Li). + / Li), cycle charge and discharge 3 times; then charge the solid-state battery cells to 4.3V at a current density of 0.33C (vs. Li). + / Li), let stand for 10 minutes, and then discharge to 2.8V at a current density of 0.33C (vs. Li). + / Li), the discharge specific capacity at this time is recorded as C1. The solid-state battery cell is cycled 200 times at a current density of 0.33C, and the discharge capacity at this time is recorded as C2.

[0244] Solid-state battery cell capacity retention rate after 30 cycles = C2 / C1 × 100%.

[0245] The battery performance test results of the above embodiments and comparative examples are shown in Table 1.

[0246] Table 1

[0247]

[0248] It's better to use ※ to indicate the result.

[0249] △ indicates that the effect is average.

[0250] × indicates poor performance.

[0251] As can be seen from the above test results, this application achieves atomic-level precise deposition and nanoscale uniform coating by using a double-layer coating of solid electrolyte and LZO and ALD / MLD technology. This solves the problem that a single layer of LZO cannot simultaneously solve the problems of lattice mismatch (core-shell interphase) and electrolyte compatibility, blocks the dissolution of transition metals, suppresses interfacial side reactions, improves wettability with sulfide electrolytes, and reduces interfacial impedance; thus improving the coulombic efficiency and cycle performance of the battery.

[0252] It should be noted that this application 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 application are included in the technical scope of this application. 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, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A positive electrode plate, characterized in that, 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 first coating material located on at least a portion of the surface of the matrix material, and a second coating material located on the surfaces of the first coating material and the matrix material. The first coating material includes LZO. The second coating material includes a solid electrolyte material, which includes one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, or lithium niobium phosphorus oxide.

2. The positive electrode sheet according to claim 1, characterized in that, The matrix material is composed of Li a Ni b Co c M d O e A f Where 0.8≤a≤1.2, 0.3≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes one or more of N, F, S and Cl.

3. The positive electrode sheet according to claim 1, characterized in that, The matrix material is composed of LiNi b Co c Mn d O2, where b≥0.9, c+d=1-b.

4. The positive electrode sheet according to claim 1, characterized in that, The matrix material is composed of LiNi 0.9 Co 0.05 Mn 0.05 O2.

5. The positive electrode sheet according to any one of claims 1-4, characterized in that, The first coating material comprises gLi2O-ZrO2, where g = 1.2 ± 0.

1.

6. The positive electrode sheet according to any one of claims 1-4, characterized in that, The average particle size of the sulfide solid electrolyte material is 1 nm-20 μm.

7. The positive electrode sheet according to any one of claims 1-4, characterized in that, The average particle size of the positive electrode active material is 3μm-10μm.

8. The positive electrode sheet according to any one of claims 1-4, characterized in that, The mass ratio of the positive electrode active material to the sulfide solid electrolyte material is 99:1 to 70:

30.

9. The positive electrode sheet according to any one of claims 1-4, characterized in that, The positive electrode also includes a conductive agent and / or a binder.

10. The positive electrode sheet according to any one of claims 1-4, characterized in that, 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.

11. A solid-state battery cell, characterized in that, It includes a negative electrode, a solid electrolyte membrane, and a positive electrode as described in any one of claims 1-10, wherein the solid electrolyte membrane is located between the negative electrode and the positive electrode.

12. The solid-state battery cell according to claim 11, characterized in that, 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.

13. A battery device, characterized in that, It includes the solid-state battery cells according to any one of claims 11-12.

14. An electrical appliance, characterized in that, Includes the solid-state battery cell according to any one of claims 11-12 or the battery device according to claim 13.

15. A positive electrode active material, characterized in that, The positive electrode active material includes a matrix material, a first coating material located on at least a portion of the surface of the matrix material, and a second coating material located on the surfaces of the first coating material and the matrix material. The first coating material includes LZO, and the second coating material includes a solid electrolyte material. The solid electrolyte material includes one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, or lithium niobium phosphorus oxide.

16. A method for preparing a positive electrode active material, characterized in that, Includes the following steps: S1: Prepare a matrix material; S2: A first coating layer is formed by coating the surface of the base material with a first coating material; S3: A second coating material is coated onto the surface of the first coating layer to form a second coating layer; The first coating material includes LZO, and the second coating material includes a solid electrolyte material, wherein the solid electrolyte material includes one or more of lithium germanium phosphorus oxide, lithium silicon phosphorus oxide, lithium aluminum phosphorus oxide, lithium boron phosphorus oxide, lithium titanium phosphorus oxide, or lithium niobium phosphorus oxide.

17. The method for preparing the positive electrode active material according to claim 16, characterized in that, The matrix material is composed of LiNi b Co c Mn d O2, where b≥0.9, c+d=1-b; and / or, The first coating material comprises gLi2O-ZrO2, where g = 1.2 ± 0.1.

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