Solid-state battery and preparation method therefor, positive electrode sheet, and electric device

Abstract

A solid-state battery and a preparation method therefor, a positive electrode sheet, and an electric device. The solid-state battery comprises a positive electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film provided on at least one surface of the positive electrode current collector; the positive electrode film comprises a positive electrode active material, a sulfide electrolyte, a binder, and toughening fibers; and the weight percentage of the toughening fibers in the positive electrode film ranges from 0.1% to 3%.

Description

Solid-state batteries, their preparation methods, positive electrode plates, and electrical devices thereof Cross-referencing

[0001] This application incorporates Chinese Patent Application No. 202510016599.6, filed on January 6, 2025, entitled "Solid-state battery and method for preparation thereof, positive electrode and electrical device", which is incorporated herein by reference in its entirety. Technical Field

[0002] This application relates to the field of solid-state battery technology, and in particular to solid-state batteries and their preparation methods, positive electrode sheets, and electrical devices. Background Technology

[0003] Solid-state batteries use non-flammable solid electrolytes instead of the organic electrolytes in traditional liquid secondary batteries, significantly improving battery safety and are considered the next generation of batteries closest to industrialization. However, in solid-state batteries, the poor electrochemical performance of the positive electrode based on sulfide electrolytes results in less than ideal initial efficiency and capacity. Summary of the Invention

[0004] In view of the above problems, this application provides a solid-state battery, a method for preparing the same, a positive electrode, and an electrical device thereof. This solid-state battery has improved initial efficiency and capacity.

[0005] The first aspect of this application provides a solid-state battery, which includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode film disposed on at least one surface of the positive current collector, the positive electrode film including a positive active material, a sulfide electrolyte, a binder and toughening fibers;

[0006] The toughening fibers constitute 0.1% to 3% of the weight of the positive electrode membrane.

[0007] In the solid-state battery provided in this application, the positive electrode film includes a positive electrode active material, a sulfide electrolyte, a binder, and toughening fibers. Introducing toughening fibers at a weight percentage of 0.1% to 3% into the positive electrode film allows for the elimination of prolonged high-speed rotation and high-shear conditions during the film's fabrication to promote sufficient fiberization of the binder. This not only reduces side reactions between the positive electrode active material and the sulfide electrolyte under localized high temperatures but also reduces particle breakage of the positive electrode active material under prolonged shear conditions, thereby promoting the electrochemical performance of the positive electrode and improving the initial efficiency and capacity of the solid-state battery. Furthermore, the toughening fibers can synergistically work with the fiberized binder to construct a robust three-dimensional network structure, providing strong support for the positive electrode active material and the sulfide electrolyte, thus enhancing the mechanical properties of the positive electrode and improving the cycle performance of the solid-state battery.

[0008] In some embodiments, the toughening fibers constitute 0.5% to 2.5% of the weight of the positive electrode film. This results in particularly outstanding electrochemical and mechanical properties of the positive electrode, significantly improving the first-efficiency, capacity, and cycle performance of the solid-state battery.

[0009] In some embodiments, the toughening fiber includes at least one selected from cellulose fiber, glass fiber, and zirconium oxide fiber. Therefore, the toughening fiber possesses excellent mechanical properties and does not react with the positive electrode active material and sulfide electrolyte during high-speed, high-shear processes, thus promoting the stable performance of the electrochemical properties of the positive electrode sheet.

[0010] In some embodiments, the toughening fibers have a length of 0.01 mm to 5 mm. This allows the toughening fibers to have a suitable fiber length, which helps to construct a fully fibrous network, thereby improving the mechanical properties of the positive electrode sheet.

[0011] In some embodiments, the toughening fibers have a diameter of 0.1 μm to 30 μm. Thus, the toughening fibers have a suitable diameter, which can provide excellent mechanical properties while promoting the uniform dispersion of the positive electrode active material and the sulfide electrolyte, thus facilitating the construction of a good ion-conducting network.

[0012] In some embodiments, the aspect ratio of the toughening fibers is 2 to 1000. This enhances the toughness and strength of the positive electrode, optimizes the ion transport network, and maintains the structural stability of the positive electrode membrane during charging and discharging.

[0013] In some embodiments, the tensile strength of the toughening fiber is 50 MPa to 1500 MPa. This enhances the mechanical properties of the positive electrode film, reduces the probability of cracks or breakage during the roll forming process, and improves its structural stability during battery charging and discharging.

[0014] In some embodiments, the tensile modulus of the toughening fiber is ≥200 MPa. This enhances the deformation resistance of the positive electrode film, reduces the probability of cracks or breakage during roll forming and charge / discharge cycles, thereby improving the battery's initial efficiency, capacity, and cycle performance.

[0015] In some embodiments, the specific surface area of ​​the toughening fiber is ≥1m². 2 / g. Therefore, the toughening fiber has a large specific surface area, which can provide more surface sites to interact with other components, making the interfacial bonding between the toughening fiber and other components tighter, thereby improving the mechanical properties of the positive electrode membrane.

[0016] In some embodiments, the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (50–88):(5–40):(0.1–3). This ensures thorough mixing of the positive electrode active material and the sulfide electrolyte, forming a continuous and effective ion transport channel, improving ion transport efficiency, and thus optimizing electrochemical performance. Simultaneously, this weight ratio of binder can improve the mechanical properties of the positive electrode sheet and reduce the loss of initial efficiency and capacity of the battery.

[0017] In some embodiments, the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (64–85):(10–30):(0.5–2.5). This further enhances the mechanical and electrochemical properties of the positive electrode, thereby improving the battery's initial efficiency, capacity, and cycle performance.

[0018] In some embodiments, the positive electrode active material comprises at least one of olivine-structured lithium phosphates and their modified compounds, and lithium transition metal oxides and their modified compounds. Thus, the solid-state battery exhibits excellent initial efficiency, capacity, and energy density.

[0019] In some embodiments, the sulfide electrolyte includes at least one of Thio-LISICON type solid-state electrolyte, Argyrodite type solid-state electrolyte, and LGPS type solid-state electrolyte. This improves the electrical performance of the solid-state battery.

[0020] In some embodiments, the binder includes at least one selected from polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, polyacrylate, and polyurethane. Therefore, the above-mentioned binder has good thermal melt properties, can be fiberized under shear force, and can connect with powder particles through point contact at high temperatures, thereby forming a strong fibrous network.

[0021] In some embodiments, the positive electrode film further includes a conductive agent. This improves the electronic conductivity of the positive electrode film, reduces the internal resistance of the positive electrode, and thus enhances the battery's initial efficiency, capacity, and energy density.

[0022] In some embodiments, the conductive agent includes at least one selected from conductive carbon black, conductive graphite, acetylene black, carbon nanotubes, graphene, and carbon fibers. This allows for the formation of continuous electron transport channels within the positive electrode film, reducing the internal resistance of the positive electrode film.

[0023] In some embodiments, the conductive agent comprises 0.5% to 4% by weight in the positive electrode film. This allows the conductive agent to construct a more complete electron transport network within the positive electrode film, optimizing electron conduction performance and improving battery capacity and energy density.

[0024] In some embodiments, the thickness of the positive electrode film is 50 μm to 300 μm. Therefore, the positive electrode film has a suitable thickness, which can improve the electrochemical performance of the battery while saving internal space.

[0025] In some embodiments, the solid-state battery is an all-solid-state battery. This further enhances the safety performance of the solid-state battery.

[0026] A second aspect of this application provides a method for preparing a solid-state battery, comprising the following steps:

[0027] The positive electrode active material, sulfide electrolyte, binder and toughening fiber are mixed to obtain a mixture;

[0028] The mixture is subjected to a film-forming process to obtain a positive electrode film;

[0029] The positive electrode film is attached to at least one surface of the positive electrode current collector to obtain a positive electrode sheet;

[0030] The positive electrode sheet is assembled to obtain the solid-state battery;

[0031] The toughening fibers constitute 0.1% to 3% of the weight of the positive electrode membrane.

[0032] In the solid-state battery preparation method provided in this application, by adding toughening fibers at a weight percentage of 0.1% to 3%, the binder can be fully fibrosed without prolonged high-speed rotation and high-shear action during the mixture preparation process. This not only reduces the occurrence of side reactions between the positive electrode active material and the sulfide electrolyte under localized high temperatures, but also reduces the problem of particle breakage of the positive electrode active material under prolonged shear action, thereby promoting the electrochemical performance of the positive electrode sheet and improving the first-time efficiency and capacity of the solid-state battery. In addition, the toughening fibers can synergistically work with the fibrous binder to jointly construct a fully three-dimensional network structure, providing strong support for the positive electrode active material and the sulfide electrolyte, thereby improving the mechanical properties of the positive electrode sheet and thus improving the cycle performance of the solid-state battery.

[0033] In some embodiments, the toughening fibers constitute 0.5% to 2.5% of the weight of the positive electrode film. This results in particularly outstanding electrochemical and mechanical properties of the positive electrode, significantly improving the first-efficiency, capacity, and cycle performance of the solid-state battery.

[0034] In some embodiments, the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (50–88):(5–40):(0.1–3). This ensures thorough mixing of the positive electrode active material and the sulfide electrolyte, forming a continuous and effective ion transport channel, improving ion transport efficiency, and thus optimizing electrochemical performance. Simultaneously, this weight ratio of binder can improve the mechanical properties of the positive electrode sheet and reduce the loss of initial efficiency and capacity of the battery.

[0035] In some embodiments, the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (64–85):(10–30):(0.5–2.5). This further enhances the mechanical and electrochemical properties of the positive electrode, thereby improving the battery's initial efficiency, capacity, and cycle performance.

[0036] In some embodiments, the positive electrode active material, sulfide electrolyte, binder, and toughening fibers are mixed under the following conditions: mixing temperature of 45°C to 200°C, mixing speed of 1000 rpm to 6000 rpm, and mixing time of 5 min to 60 min. This allows the binder to undergo fibrous treatment, enabling it to co-construct a more complete fibrous network with the toughening fibers within a shorter mixing time. This reduces the probability of side reactions occurring between the positive electrode active material and the sulfide electrolyte at high temperatures, and also reduces the probability of particle breakage in the positive electrode active material, thereby improving the initial efficiency and capacity of the positive electrode sheet.

[0037] In some embodiments, the positive electrode active material, sulfide electrolyte, binder, and toughening fiber are mixed under the following conditions: mixing temperature of 60°C to 150°C, mixing speed of 2500 rpm to 5000 rpm, and mixing time of 10 min to 30 min. This further improves the initial efficiency and capacity of the positive electrode sheet, while also enhancing its mechanical properties.

[0038] In some embodiments, the mixture is subjected to a film-forming process, including the following steps: roll forming at a temperature of 45°C to 200°C to obtain a positive electrode film. This allows the positive electrode film to be rolled thinned, achieving a suitable thickness and loading capacity.

[0039] A third aspect of this application provides a positive electrode sheet. The positive electrode sheet includes a positive current collector and a positive electrode membrane disposed on at least one surface of the positive current collector. The positive electrode membrane includes a positive active material, a sulfide electrolyte, a binder, and toughening fibers.

[0040] The toughening fibers constitute 0.1% to 3% of the weight of the positive electrode membrane.

[0041] In the positive electrode sheet provided in this application, toughening fibers are introduced into the positive electrode film at a weight percentage of 0.1% to 3%. This allows the positive electrode film to be prepared without prolonged high-speed rotation and high-shear action to promote sufficient fiberization of the binder. This not only reduces the occurrence of side reactions between the positive electrode active material and the sulfide electrolyte under local high temperatures, but also reduces the problem of particle breakage of the positive electrode active material under prolonged shear action, thereby promoting the electrochemical performance of the positive electrode sheet. In addition, the toughening fibers can synergistically work with the fiberized binder to jointly construct a fully developed three-dimensional network structure, providing strong support for the positive electrode active material and the sulfide electrolyte, thereby improving the mechanical properties of the positive electrode sheet. Using the positive electrode sheet provided in this application in solid-state batteries can effectively improve the initial efficiency and capacity of solid-state batteries, while also improving the cycle performance of solid-state batteries.

[0042] In some embodiments, the positive electrode is the same as the positive electrode in the aforementioned solid-state battery. This effectively improves the electrochemical and mechanical properties of the positive electrode.

[0043] A fourth aspect of this application provides an electrical device. The electrical device includes at least one of the above-described solid-state battery, a solid-state battery prepared by the above-described solid-state battery preparation method, and the above-described positive electrode. Therefore, the electrochemical performance of the electrical device is improved. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of this application, the 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. In the drawings:

[0045] Figure 1 is a schematic diagram of the positive electrode film in one embodiment of this application.

[0046] Figure 2 is a schematic diagram of a solid-state battery cell according to an embodiment of this application.

[0047] Figure 3 is an exploded view of a solid-state battery cell according to an embodiment of this application, as shown in Figure 2.

[0048] Figure 4 is a schematic diagram of a battery device according to an embodiment of this application.

[0049] Figure 5 is a schematic diagram of a battery pack according to one embodiment of this application.

[0050] Figure 6 is an exploded view of the battery pack of one embodiment of this application shown in Figure 5.

[0051] Figure 7 is a schematic diagram of an electrical device using a solid-state battery as a power source according to an embodiment of this application;

[0052] Figure 8 is a SEM image of the positive electrode film of Embodiment 1 of this application.

[0053] Explanation of reference numerals in the attached figures:

[0054] 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery assembly; 5. Solid-state battery cell; 51. Casing; 52. Solid-state battery cell; 53. Cover plate; 6. Electrical device; 7. Positive electrode membrane; 71. Positive electrode active material; 72. Sulfide electrolyte; 73. Binder; 74. Toughening fiber. Detailed Implementation

[0055] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] The "range" disclosed in this application can be defined in the form of 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. Any endpoint can be included or excluded independently and can be combined arbitrarily; 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 ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also 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" and "5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when describing a parameter as an integer ≥ 2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 for that parameter. For instance, when describing a parameter as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0058] In this application, unless otherwise specified, "about" means within a reasonable range above and below the stated number, and the range of fluctuation may vary depending on the type and value of the stated number. For example, a range of ±10%, ±5%, ±2%, ±1%, etc., may be allowed. For example, taking "about 20°C" and its approximation as ±1°C, approximate values ​​such as 19°C, 19.5°C, etc., within the approximation range indicated by "about 20°C" should also be included in the range indicated by "about 20°C".

[0059] In this application, the terms "multiple," "various," "multiple items," "several," etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more (greater than or equal to) two. It can be understood that when "any number of" items are involved, it refers to any suitable combination of multiple items, that is, a combination of "any number of" items in a manner that does not conflict and enables the implementation of this application.

[0060] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0061] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0062] Those skilled in the art will understand that the order in which the steps are written in the methods of various embodiments or examples does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but are preferably performed sequentially. For example, if method M includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, method M may also include step (c), meaning that step (c) can be added to method M in any order. For example, method M 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.

[0063] In this application, open-ended technical features or solutions described using terms such as "containing," "comprising," or "including" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, if 'a' includes a1, a2, and a3, it may also include other members or exclude additional members unless otherwise specified. This can be considered as providing both features or solutions where "a consists of a1, a2, and a3" or "a is selected from a1, a2, and a3," and features or solutions where "a includes not only a1, a2, and a3, but also other members."

[0064] In this application, unless otherwise specified, M (e.g., m1) means that m1 is a non-limiting example of M, and it is understood that M is not limited to m1.

[0065] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it is selected from either "with" or "without." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent. Unless otherwise specified, the descriptions such as "optionally include" and "optionally contain" in this application, taking "optionally include" as an example, mean "may include or not include."

[0066] In this application, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. Any and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "M and / or N" represents the group consisting of M, N, and "a combination of M and N". "Containing M and / or N" can mean "containing M, containing N, and containing both M and N", or "containing M, containing N, or containing both M and N", and can be appropriately understood according to the context.

[0067] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0068] In this document, the term "suitable" in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the technical solution that enables the implementation of this application.

[0069] In this document, terms such as "preferred," "better," "more suitable," "ideal," "good," and "superior" are merely descriptions of more effective implementation methods or embodiments, and should be understood not to limit the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "preferred" term shall be independent.

[0070] In this application, terms such as "further," "even more," "especially," "for example," "as," "example," and "exemplary" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0071] In this application, the terms "first aspect," "second aspect," "third aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0072] In this application, unless otherwise expressly specified and limited, the phrase "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In this application, unless otherwise expressly specified and limited, the phrase "above" or "below" the second feature can indicate a horizontal positional relationship, or it can simply indicate the existence of an attachment relationship without specifying a horizontal positional relationship.

[0073] In this application, the term "room temperature" generally refers to 4℃ to 35℃, and may refer to 20℃ ± 5℃. In some embodiments or examples of this application, room temperature refers to 20℃ to 30℃.

[0074] In this application, if the unit for a data range is only followed by the right endpoint, it indicates that the units for the left and right endpoints are the same. For example, 3~5h or 3-5h both mean that the unit for the left endpoint "3" and the right endpoint "5" is h (hours), and both have the same meaning as 3h~5h. Furthermore, similar descriptions of other parameters such as temperature and size are interpreted in the same way.

[0075] In this application, the exemplary descriptions such as "in some implementations (or embodiments)" and "in one implementation (or embodiment)" may cover, but are not limited to, the following meanings: these solutions can be combined with other solutions in a suitable manner to form new technical solutions.

[0076] In the fabrication of solid-state batteries, the main processes for preparing the positive electrode film include wet and dry processes. The wet process involves mixing the positive electrode active material, binder, and solvent to form a positive electrode slurry. Then, after the solvent evaporates, the binder precipitates onto the surface of the particles of each component, thus obtaining the positive electrode film. However, traditional solvent systems are polar solvents, such as N-methylpyrrolidone (NMP) or deionized water. In solid-state batteries based on sulfide electrolytes, polar solvents easily react with the sulfide electrolyte, leading to performance degradation. Therefore, a solvent-free dry process is more suitable for preparing the positive electrode film of solid-state batteries.

[0077] In the dry process for preparing the positive electrode membrane, high-speed mixing is required to uniformly mix the powder particles of the positive electrode active material, sulfide electrolyte, and other components with the binder. High-speed shearing force is then used to fiberize the binder, allowing it to adhere uniformly to the powder particles and connect them together to provide strong mechanical properties. The mixture is then subjected to multi-stage roll forming to gradually reduce the thickness of the positive electrode membrane to the target thickness. By controlling the thickness, the positive electrode membrane can achieve the target loading capacity.

[0078] During the rolling and thinning process of the positive electrode membrane, the internal particles are constantly rubbing against each other. Because there are particles of different sizes in the positive electrode membrane, the hard friction between the particles increases, making it difficult to thin the electrode. A high-torque roller press is required for extrusion, which makes the positive electrode membrane prone to defects such as cracks during the thinning process. These defects will damage the ion network and electron network of the positive electrode membrane, affecting the stable performance of the electrochemical properties of the positive electrode.

[0079] To reduce the probability of crack formation, it is typically necessary to improve the mechanical properties of the positive electrode membrane. These mechanical properties are primarily provided by the fibrous binder. Individual binder particles undergo fibrosis under high shear forces, causing individual fibers to uniformly wrap around other component particles, forming a network-like framework that provides robust mechanical properties. Therefore, sufficient fibrosis of the binder, while ensuring uniform fiber coverage between particles, is crucial for improving the mechanical properties of the positive electrode membrane. However, the process of fibrosis through high-speed mixing often requires high rotation speeds and high shear rates. This can easily lead to particle breakage of the positive electrode active material under prolonged high shear, thus affecting the performance of the positive electrode. Simultaneously, the prolonged high-rotation, high-shear mixing process can also cause heat accumulation and localized high temperatures, leading to high-temperature side reactions between the positive electrode active material and the sulfide electrolyte. This can cause the positive electrode active material to fail, resulting in poor electrochemical performance of the positive electrode and ultimately, less than ideal initial efficiency and capacity of the battery.

[0080] In view of this, this application provides a solid-state battery and its preparation method, positive electrode, and power supply device. This solid-state battery has improved initial efficiency and capacity.

[0081] In a first aspect, this application provides a solid-state battery, which includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode film disposed on at least one surface of the positive current collector, the positive electrode film including a positive active material, a sulfide electrolyte, a binder and toughening fibers; the weight percentage of the toughening fibers in the positive electrode film is 0.1% to 3%.

[0082] Unless otherwise specified, the term "solid-state battery" in this application refers to a battery in which the electrolyte includes a solid electrolyte. Typically, a solid-state battery includes a positive electrode, a solid electrolyte membrane, and a negative electrode. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The solid electrolyte membrane acts as a conductor of ions between the positive and negative electrodes and also isolates them, preventing short circuits. Therefore, a separator, as found in traditional lithium-ion batteries, is not required in solid-state batteries. Solid-state batteries use a non-flammable solid electrolyte instead of the organic electrolyte in traditional liquid lithium-ion batteries, significantly improving battery safety. In addition to enhanced safety, solid-state batteries are better suited for high-energy-density positive and negative electrode materials and reduce system weight, thus facilitating improvements in energy density.

[0083] In this application, unless otherwise specified, "solid electrolyte" refers to an electrolyte material or substance that exists in solid form during the storage and fabrication of solid-state batteries and components constituting solid-state batteries, as well as during the operation of solid-state batteries. This includes, but is not limited to, solid electrolytes existing in solid form at room temperature.

[0084] In this application, unless otherwise specified, "positive electrode sheet" includes positive electrode active material. "Positive electrode active material" refers to a substance used in the positive electrode sheet that is capable of reversibly extracting and inserting active ions. Correspondingly, "negative electrode sheet" includes negative electrode active material. "Negative electrode active material" refers to a substance used in the negative electrode sheet that is capable of reversibly inserting and extracting active ions. During solid-state battery charging, active ions are extracted from the positive electrode, pass through the solid electrolyte layer, and insert into the negative electrode; while during solid-state battery discharging, active ions are extracted from the negative electrode and insert into the positive electrode. The active ions are not particularly limited or restrictive; they can be lithium ions, in which case it corresponds to a lithium-ion solid-state battery.

[0085] In this application, unless otherwise specified, "sulfide electrolyte" in the positive electrode membrane refers to a sulfide solid electrolyte. Sulfide electrolytes can enhance the ion conductivity of the positive electrode membrane, reduce interfacial impedance, and promote the charge transfer efficiency and full release of the capacity of the positive electrode active material with the external environment.

[0086] In this application, unless otherwise specified, "initial efficiency" refers to the initial coulombic efficiency (ICE), which is the ratio of the discharge specific capacity to the charge specific capacity of a solid-state battery during its first charge-discharge cycle. It is usually expressed as a percentage and is an important indicator for measuring the energy conversion efficiency of a solid-state battery during its first charge-discharge cycle.

[0087] Figure 1 shows an example of a positive electrode film 7, with the black arrows indicating the direction of tension. In the positive electrode of a solid-state battery, the positive electrode film 7 comprises a positive active material 71, a sulfide electrolyte 72, a binder 73, and toughening fibers 74. Introducing toughening fibers 74 at a weight percentage of 0.1% to 3% into the positive electrode film 7 eliminates the need for prolonged high-speed rotation and high-shear action during its fabrication to fully fiberize the binder 73. This not only reduces side reactions between the positive active material 71 and the sulfide electrolyte 72 under localized high temperatures but also reduces particle breakage of the positive active material 71 under prolonged shear action, thereby promoting the electrochemical performance of the positive electrode and ultimately improving the initial efficiency and capacity of the solid-state battery. In addition, the toughening fiber 74 can work synergistically with the fibrous binder 73 to jointly construct a fully three-dimensional network structure, providing strong support for the positive electrode active material 71 and the sulfide electrolyte 72, thereby improving the mechanical properties of the positive electrode sheet and thus improving the cycle performance of the solid-state battery.

[0088] In some embodiments, the toughening fiber constitutes 0.1% to 3% by weight in the positive electrode membrane, for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, or any range of the above values. Therefore, using toughening fibers at this content can effectively shorten the mixing time during the preparation of the positive electrode membrane, improve the electrochemical performance of the positive electrode, and facilitate the improvement of mechanical properties.

[0089] In some embodiments, the toughening fibers constitute 0.5% to 2.5% of the weight of the positive electrode film. This results in particularly superior electrochemical and mechanical properties of the positive electrode, significantly improving the first-efficiency, capacity, and cycle performance of the solid-state battery. In some specific embodiments, the toughening fibers can constitute 1% to 2% of the weight of the positive electrode film.

[0090] In some embodiments, the toughening fiber includes at least one selected from cellulose fiber, glass fiber, and zirconium oxide fiber. Therefore, the aforementioned toughening fiber possesses good mechanical properties and does not react with the positive electrode active material and sulfide electrolyte during high-speed, high-shear processes, promoting the stable performance of the electrochemical properties of the positive electrode sheet. In some specific embodiments, the toughening fiber may include cellulose fiber.

[0091] In some embodiments, the length of the toughening fiber is 0.01 mm to 5 mm. In this application, the length of the toughening fiber has a meaning known in the art and can be tested using instruments and methods known in the art, such as GB / T 6502-2017 or GB / T14336-2017. As a non-limiting example, the length of the toughening fiber can be 0.01 mm, 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm, or a range of any of the above values. Thus, the toughening fiber has a suitable fiber length, which helps to construct a sufficiently fibrous network, thereby improving the mechanical properties of the positive electrode sheet. In some specific embodiments, the length of the toughening fiber can be 0.5 mm to 3 mm.

[0092] In this application, the unit "mm" refers to millimeters.

[0093] In some embodiments, the diameter of the toughening fiber is 0.1 μm to 30 μm. In this application, the diameter of the toughening fiber has a meaning known in the art and can be tested using instruments and methods known in the art, for example, with reference to GB / T 21300-2007. As a non-limiting example, the diameter of the toughening fiber can be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, or 30 μm, or a range of any of the above values. Thus, the toughening fiber has a suitable diameter, which can provide excellent mechanical properties while promoting the uniform dispersion of the positive electrode active material and the sulfide electrolyte, which is beneficial for constructing a good ion-conducting network. In some specific embodiments, the diameter of the toughening fiber can be 0.1 μm to 30 μm.

[0094] In this application, the unit "μm" refers to micrometers.

[0095] In some embodiments, the aspect ratio of the toughening fiber is 2 to 1000. In this application, the aspect ratio of the toughening fiber refers to the ratio of the fiber's length to its diameter, and can be measured using instruments and methods known in the art. For example, the aspect ratio can be calculated after measuring the length and diameter of the toughening fiber using the methods described above. As a non-limiting example, the aspect ratio of the toughening fiber can be 2, 5, 10, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000, or a range of any of the above values. This enhances the toughness and strength of the positive electrode sheet, optimizes the ion transport network, and maintains the structural stability of the positive electrode membrane during charging and discharging. In some specific embodiments, the aspect ratio of the toughening fiber can be 5 to 500.

[0096] In some embodiments, the tensile strength of the toughening fiber is 50 MPa to 1500 MPa. In this application, the tensile strength of the toughening fiber has a meaning known in the art and can be tested using instruments and methods known in the art, such as GB / T 14337-2008, GB / T14338-2008, or GB / T 19975-2005. As a non-limiting example, the tensile strength of the toughening fiber can be 50 MPa, 100 MPa, 200 MPa, 400 MPa, 600 MPa, 800 MPa, 1000 MPa, 1200 MPa, or 1500 MPa, or a range of any of the above values. This can enhance the mechanical properties of the positive electrode film, reduce the probability of cracks or breakage during the roll forming process, and improve its structural stability during battery charging and discharging. In some specific embodiments, the tensile strength of the toughening fiber can be 100 MPa to 800 MPa.

[0097] In some embodiments, the tensile modulus of the toughening fiber is ≥200 MPa. In this application, the tensile modulus of the toughening fiber has a meaning known in the art and can be tested using instruments and methods known in the art, for example, with reference to T / CSTM 00443-2023. As an example, the tensile modulus of the toughening fiber can be 200 MPa, 500 MPa, 1 GPa, 5 GPa, 10 GPa, 15 GPa, 20 GPa, 25 GPa, 30 GPa, 50 GPa, 75 GPa, 100 GPa, 125 GPa, 150 GPa, 175 GPa, or 200 GPa, or a range of any of the above values. This enhances the deformation resistance of the positive electrode film, reduces the probability of cracks or breakage during rolling thinning and charge-discharge cycles, thereby improving the battery's first-efficiency, capacity, and cycle performance. In some specific embodiments, the tensile modulus of the toughening fiber can be 1 GPa to 150 GPa.

[0098] In this application, the unit "MPa" refers to megapascals and "GPa" refers to gigapascals.

[0099] In some embodiments, the specific surface area of ​​the toughening fiber is ≥1m². 2 / g. In this application, the specific surface area of ​​the toughening fiber has a meaning known in the art and can be tested using instruments and methods known in the art, such as GB / T 19587-2017. As a non-limiting example, the specific surface area of ​​the toughening fiber can be 1m². 2 / g、5m 2 / g, 10m 2 / g、25m 2 / g, 50m 2 / g、75m 2 / g, 100m 2 / g、125m 2 / g, 150m 2 / g、175m 2 / g、200m 2 / g、225m 2 / g、250m 2 / g、300m 2 / g、400m 2 / g or 500m 2 / g, or any of the above values. Therefore, the toughening fiber has a large specific surface area, providing more surface sites for interaction with other components, resulting in a tighter interfacial bond between the toughening fiber and other components, thereby improving the mechanical properties of the positive electrode membrane. In some specific embodiments, the specific surface area of ​​the toughening fiber can be 10m². 2 / g~250m 2 / g.

[0100] In this application, the unit "m" 2 " / g" refers to square meters per gram.

[0101] In some embodiments, the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (50–88):(5–40):(0.1–3). As a non-limiting example, in the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder, the value corresponding to the positive electrode active material can be 50, 55, 60, 65, 70, 75, 80, 85, or 88, or a range of any of the above values; the value corresponding to the sulfide electrolyte can be 5, 10, 15, 20, 25, 30, 35, or 40, or a range of any of the above values; the value corresponding to the binder can be 0.1, 0.5, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, or 3, or a range of any of the above values. Thus, the positive electrode active material and sulfide electrolyte are thoroughly mixed and form a continuous and effective ion transport channel, improving ion transport efficiency and thus optimizing electrochemical performance. At the same time, the binder at this weight ratio can improve the mechanical properties of the positive electrode sheet and reduce the loss of the battery's initial efficiency and capacity.

[0102] In some embodiments, the weight ratio of the positive electrode active material, sulfide electrolyte, and binder is (64–85):(10–30):(0.5–2.5). This further enhances the mechanical and electrochemical properties of the positive electrode, thereby improving the battery's initial efficiency, capacity, and cycle performance. In some specific embodiments, the weight ratio of the positive electrode active material, sulfide electrolyte, and binder can be (80–85):(10–15):(0.8–1.2).

[0103] In some embodiments, the positive electrode active material constitutes 50% to 88% of the weight of the positive electrode film, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 88%, or any range thereof. This improves ion transport efficiency and helps to enhance the battery's initial efficiency, capacity, and energy density. In some embodiments, the positive electrode active material constitutes 64% to 85% of the weight of the positive electrode film, and more specifically, 80% to 85%.

[0104] In some embodiments, the sulfide electrolyte constitutes 5% to 40% of the positive electrode membrane by weight, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, or any range thereof. This promotes uniform dispersion of the sulfide electrolyte in the positive electrode membrane, constructing a good ion transport network. In some embodiments, the sulfide electrolyte constitutes 10% to 30% of the positive electrode membrane by weight, more specifically, 10% to 15%.

[0105] In some embodiments, the binder constitutes 0.1% to 3% by weight in the positive electrode membrane, for example, 0.1%, 0.5%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%, or any range of the above values. This provides sufficient binder to offer a good fibrous network, effectively improving the mechanical properties of the positive electrode while maintaining its electrochemical performance, reducing the impact of binder on initial efficiency and capacity. In some embodiments, the binder constitutes 0.5% to 2.5% by weight in the positive electrode membrane, more specifically, 1% to 2%.

[0106] In some embodiments, the positive electrode active material includes at least one of olivine-structured lithium phosphates and their modified compounds, and lithium transition metal oxides and their modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Non-limiting examples of olivine-structured lithium phosphates include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their modified compounds. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 Examples of lithium nickel cobalt aluminum oxides include LiNi, etc. 0.8 Co 0.15 Al 0.05 O2. In some embodiments, the positive electrode active material includes at least one selected from lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2 or LiMn2O4), lithium iron phosphate (LiFePO4), and lithium nickel cobalt manganese oxide (NCM), and may further include lithium nickel cobalt manganese oxide (NCM). Thus, the solid-state battery exhibits excellent initial efficiency, capacity, and energy density.

[0107] In some embodiments, the sulfide electrolyte includes at least one of Thio-LISICON type solid electrolyte, Argyrodite type solid electrolyte, and LGPS (lithium germanium phosphorus sulfur) type solid electrolyte. However, the present application is not limited to these materials, and other conventional materials that can be used as battery sulfide electrolytes can also be used. These sulfide electrolytes can be used alone or in combination of two or more. The crystal structure of these sulfides can be at least one of glassy state, glass-ceramic state, and crystalline state. Among them, the expression of Thio-LISICON type solid electrolyte can be Li 4-x A 1-x B x S4, 0 < x < 1, A includes at least one of Ge and Si, B includes at least one of P, Al, and Zn. For example, it can include Li 3.25 Ge 0.25 P 0.7 S4; The Argyrodite type solid electrolyte can include at least one of Li6PS5X and Li 5.5 PS 5.5 X 1.5 where X includes at least one of Cl, Br, and I. For example, it can include Li6PS5Cl and Li 5.5 PS 5.5 Cl 1.5 ; The LGPS type solid electrolyte can include Li 10 GeP2S 12 . In some specific embodiments, the sulfide electrolyte can include at least one of Li6PS5Cl (which can be abbreviated as LPSCl) and Li 10 GeP2S 12 (which can be abbreviated as LGPS). Thus, the electrical performance of the solid-state battery is improved.

[0108] In some embodiments, the binder includes at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, polyacrylate, and polyurethane. Thus, the above binder has good hot-melt property, can be fibrillated under the action of shear force, and is connected with powder particles in the form of point contact at high temperature, thereby forming a strong fibrillar network. In some specific embodiments, the binder can include polytetrafluoroethylene (PTFE).

[0109] In some embodiments, the positive electrode film also includes a conductive agent. Thus, the electronic conductivity of the positive electrode film can be improved, the internal resistance of the positive electrode sheet can be reduced, and thereby the initial efficiency, capacity, and energy density of the battery can be improved.

[0110] In some embodiments, the conductive agent includes at least one selected from conductive carbon black, conductive graphite, acetylene black, carbon nanotubes, graphene, and carbon fibers. As a non-limiting example, the conductive agent may include at least one selected from SP, KS-6, acetylene black, vapor-grown carbon fibers (VGCF), carbon nanotubes (CNTs), and graphene. This allows for the formation of continuous electron transport channels in the positive electrode film, reducing the internal resistance of the positive electrode film. In some specific embodiments, the conductive agent may include vapor-grown carbon fibers (VGCF).

[0111] In some embodiments, the conductive agent comprises 0.5% to 4% by weight in the positive electrode film, for example, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, or 4%, or any range of the above values. Therefore, the conductive agent can construct a relatively complete electron transport network in the positive electrode film, optimize electron conduction performance, and improve the battery capacity and energy density. In some specific embodiments, the conductive agent comprises 1% to 3% by weight in the positive electrode film.

[0112] In some embodiments, the thickness of the positive electrode film is 50 μm to 300 μm, for example, it can be 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, or 300 μm, or any range of the above values. Therefore, the positive electrode film has a suitable thickness, which can improve the electrochemical performance of the battery while saving internal space. In some specific embodiments, the thickness of the positive electrode film can be 80 μm to 120 μm.

[0113] In some embodiments, the positive electrode sheet further includes an undercoat layer disposed between the positive current collector and the positive electrode membrane to improve the adhesion between the positive current collector and the positive electrode membrane, thereby improving the structural stability of the positive electrode sheet. As a non-limiting example, the undercoat layer may include an adhesive and a conductive agent. In the undercoat layer, the weight percentage of the adhesive may be 30% to 70%, for example, 30%, 40%, 50%, 60%, or 70%, or any range thereof; the adhesive in the undercoat layer may include an aqueous adhesive (such as polyacrylate) and an oil-based adhesive (such as polyvinylidene fluoride or polytetrafluoroethylene). In the undercoat layer, the weight percentage of the conductive agent may be 50% to 70%, for example, 30%, 40%, 50%, 60%, or 70%, or any range thereof; the conductive agent in the undercoat layer may be at least one of conductive carbon black, conductive graphite, acetylene black, carbon nanotubes, graphene, and carbon fiber. In some specific embodiments, the primer layer may include 50% by weight of an adhesive and 50% by weight of a conductive agent. The adhesive may be polyacrylate and the conductive agent may be conductive carbon black, which can improve the structural stability and conductivity of the positive electrode sheet.

[0114] As a non-limiting example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode diaphragm is disposed on either or both of the two opposite surfaces of the positive current collector.

[0115] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be obtained by forming a metal material on the polymer material substrate. Non-limiting examples of the metal material in the positive electrode current collector may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. Non-limiting examples of the polymer material substrate in the positive electrode current collector may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0116] In some implementations, the solid-state battery is an all-solid-state battery. This further enhances the safety performance of solid-state batteries.

[0117] In this application, unless otherwise specified, "all-solid-state battery" refers to a solid-state battery in which all electrolytes are solid electrolytes. In this case, the positive electrode, negative electrode and electrolyte are all made of solid materials, and no liquid electrolyte is provided in the battery, so it can be called an "all-solid-state battery".

[0118] In some embodiments, a solid-state battery includes at least one solid-state battery cell. A solid-state battery may include one or more solid-state battery cells.

[0119] In this application, unless otherwise specified, "solid-state battery cell" refers to a basic unit capable of converting chemical energy into electrical energy, and all its components are solid-state. In some embodiments, a solid-state battery cell may be an all-solid-state battery cell.

[0120] In this application, unless otherwise specified, "all-solid-state battery cell" refers to a solid-state battery cell in which all electrolytes are solid electrolytes. In this case, the positive electrode, negative electrode and electrolyte are all made of solid materials, and no liquid electrolyte is provided in the battery cell. Therefore, it can be called an "all-solid-state battery cell".

[0121] Non-limitingly, a solid-state battery cell (which can be an all-solid-state battery cell) may include a positive electrode, a solid electrolyte membrane, and a negative electrode, with the solid electrolyte membrane located between the positive and negative electrodes. During battery charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The solid electrolyte membrane serves to conduct ions between the positive and negative electrodes and also isolates them, thus preventing short circuits between the positive and negative electrodes.

[0122] In some implementations, a solid-state battery cell includes a solid-state battery cell.

[0123] In some implementations, the solid-state cell may be an all-solid-state cell.

[0124] In some embodiments, a solid-state battery cell (which may be an all-solid-state battery cell) includes a positive electrode, a solid electrolyte membrane, and a negative electrode stacked sequentially, wherein the positive electrode is the aforementioned positive electrode.

[0125] The following is a description of the negative electrode plate.

[0126] The negative electrode can be formed based on an etched solid electrolyte membrane or provided by a pre-fabricated negative electrode, and can be a negative electrode that is available in the art for use in solid-state batteries.

[0127] The negative electrode sheet can be prepared by dry or wet methods. For example, it can be formed into a film by dry pressing. Alternatively, it can be formed into a film by wet coating.

[0128] In this application, unless otherwise stated, the negative electrode sheet includes at least a negative electrode film.

[0129] Unless otherwise stated in this application, the negative electrode membrane includes at least a negative electrode active material.

[0130] Without limitation, the negative electrode membrane may include a solid electrolyte. The solid electrolyte in the negative electrode active material layer may be referred to as "negative electrode electrolyte particles".

[0131] In this application, unless otherwise specified, "negative electrode electrolyte particles" refers to solid electrolytes that can be used in negative electrode sheets. Negative electrode electrolyte particles can enhance the ion conductivity of negative electrode sheets, reduce interfacial impedance, and promote the charge transfer efficiency and full release of capacity between the negative electrode active material and the external environment.

[0132] Without limitation, the weight percentage of the negative electrode active material in the negative electrode film can be ≥80%, and more preferably ≥90%.

[0133] Non-limitingly, the weight percentage of negative electrode electrolyte particles in the negative electrode membrane can be 0% to 30%, preferably 0.1% to 30%, and further preferably 5% to 20%.

[0134] In some implementations, the negative electrode active material is a lithium indium alloy (InLi alloy).

[0135] In some implementations, the negative electrode is an InLi alloy film.

[0136] In some embodiments, the negative electrode active material may also be a negative electrode active material known in the art for use in solid-state batteries. As a non-limiting example, the negative electrode active material may include one or more of the following materials: elemental silicon, elemental tin, silicon-carbon composites, silicon suboxide, graphite, and metallic lithium. However, this application is not limited to these materials or substances, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0137] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film disposed on at least one surface of the negative current collector, the negative electrode film comprising a negative electrode active material. As a non-limiting example, the negative current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film is disposed on either or both of the two opposite surfaces of the negative current collector.

[0138] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. In the negative electrode current collector, the composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. In the negative electrode current collector, the composite current collector may be formed by forming a metal material on the polymer material substrate. Non-limiting examples of the metal material in the negative electrode current collector may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limiting examples of the polymer material substrate in the negative electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0139] In some embodiments, the negative electrode active material layer optionally includes a conductive agent (which may be referred to as a negative electrode conductive agent). Non-limitingly, the negative electrode conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Non-limitingly, the weight percentage of the negative electrode conductive agent in the negative electrode active material layer may be 0–15 wt%, more preferably 0–10 wt%, and even more preferably 0–5 wt%.

[0140] In some embodiments, the negative electrode active material layer optionally includes a binder (denoted as negative electrode binder). As a non-limiting example, the negative electrode binder may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). Non-limitingly, the weight percentage of the negative electrode binder in the negative electrode active material layer may be 0-10%, more further 0-5%, even more further 1%-5%, and even more preferably 1%-3%.

[0141] In some embodiments, the negative electrode active material layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)). The weight percentage of the other additives in the negative electrode active material layer may be 0-15%, more preferably 0-10%, even more preferably 0-5%, even more preferably 0-3%, and even more preferably 0-2%.

[0142] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, negative electrode conductive agent, negative electrode binder, and any other components, in a solvent (a non-limiting example of a solvent is p-xylene) to form a negative electrode slurry. Further, the negative electrode slurry is coated onto at least one surface of the negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode sheet is obtained. Cold pressing can be performed using a cold rolling mill. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 30% to 70%, optionally 40% to 60%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 mPa·s to 10000 mPa·s, optionally 3000 mPa·s to 10000 mPa·s. When coating the negative electrode slurry, the coating density per unit area, based on the amount coated on one side of the negative electrode current collector and calculated by dry weight (excluding solvent), can be 1.5 mg / cm³. 2 ~22mg / cm 2 However, this is not the only possibility. The compaction density of the negative electrode sheet can be 1.0 g / cm³. 3 ~2.0g / cm 3 1.0g / cm³ is an optional value. 3 ~1.8g / cm 3 .

[0143] In this application, the unit "mPa·s" refers to millipascal-second, and the unit "mg / cm²" refers to millipascal-second. 2 "" refers to milligrams per square centimeter, with the unit "g / cm²". 3 "" refers to grams per cubic centimeter.

[0144] The term "compacted density" as used in this application has a meaning known in the art and is one of the reference indicators for the energy density of materials. In this application, unless otherwise specified, the compacted density of the positive electrode refers to the ratio of the mass of the positive electrode film to its volume, and the compacted density of the negative electrode refers to the ratio of the mass of the negative electrode film to its volume.

[0145] The following is a description of solid electrolyte membranes.

[0146] Solid electrolyte membranes can be introduced by forming electrode plates on both sides of the solid electrolyte membrane, or by introducing them onto the electrode plates. Understandably, the electrode plates can be positive or negative electrode plates.

[0147] Solid electrolyte membranes act as conductors for ions between the positive and negative electrodes, and can also isolate the positive and negative electrodes to prevent short circuits.

[0148] Understandably, a solid electrolyte membrane includes a solid electrolyte. The solid electrolyte in the solid electrolyte membrane may be a solid electrolyte known in the art that can be used in solid-state batteries.

[0149] The types of solid electrolytes present in different film layers of a solid-state battery can be the same or different. For example, the solid electrolytes in the positive electrode and the solid electrolyte film can be the same or different.

[0150] As a non-limiting example, in different film layers of a solid-state battery, the solid electrolyte may include one or more of the following: sulfide solid electrolyte, halide solid electrolyte, oxide solid electrolyte, polymer solid electrolyte, etc.

[0151] As another non-limiting example, in different film layers of a solid-state battery, the solid electrolyte can be, but is not limited to, one or more of oxide-based solid electrolytes, sulfide-based solid electrolytes, and halide-based solid electrolytes. In some embodiments, the solid electrolyte can independently include, but is not limited to, one or more of Argyrodite-type sulfide electrolytes and halide electrolytes. Non-limiting examples of oxide-based solid electrolytes may include LISICON-type oxide electrolytes (such as γ-Li3PO4), NASICON-type oxide electrolytes (such as Li... 1+x Al x Ge 2-x (PO4)3,Li 1+x Al x Ti 2-x (PO4)3, etc., 0≤x≤1), Garnet type (such as Li7La3Zr2O) 12 (etc.), perovskite-type oxide electrolytes (such as Li, etc.) 3x La 2 / 3-x One or more of the following: TiO3, etc., 0≤x≤0.5, etc. Non-limiting examples of sulfide solid electrolytes may include Li... 10 GeP2S 12 Li₂S-P₂S₅, Argyrodite type (such as Li₆PS₅Cl, Li 5.5 PS 5.5 Cl 1.5 One or more of the following (etc.). Non-limiting examples of halide solid electrolytes may include one or more of the following: Li3InCl6, Li3YCl6, Li3ScCl6, Li3ErCl6, Li2ZrCl6, etc.

[0152] Solid electrolyte membranes can be prepared using dry methods. In some embodiments, the solid electrolyte membrane can be formed by pressing solid electrolyte materials into a solid electrolyte membrane. In other embodiments, the solid electrolyte membrane is formed by pressing the constituent materials of the solid electrolyte membrane onto an electrode sheet. In still other embodiments, the solid electrolyte membrane can also be prepared using methods such as fibrosis combined with calendering, melt extrusion, or spraying.

[0153] Solid electrolyte membranes can also be prepared by wet methods, and the electrolyte slurry used includes at least a solid electrolyte and an organic solvent, and usually also includes one or more of a binder and a dispersant.

[0154] In some embodiments, the thickness of the solid electrolyte membrane can be 0.1 μm to 1000 μm, and can be selected from thicknesses such as 10 μm to 100 μm, 100 μm to 800 μm, and 500 μm to 800 μm.

[0155] In a non-limiting manner, the positive electrode, the solid electrolyte membrane, and the negative electrode can be assembled in a stacked manner, with the solid electrolyte membrane placed between the positive and negative electrode.

[0156] Non-limitingly, a solid-state battery cell can be prepared by stacking a positive electrode, a solid electrolyte membrane, and a negative electrode in sequence, placing the solid electrolyte membrane between the positive and negative electrodes, and then rolling them together.

[0157] Non-limitingly, a solid-state battery cell can be prepared by sequentially stacking a positive electrode membrane, a solid electrolyte membrane, and a negative electrode membrane, with the solid electrolyte membrane placed between the positive and negative electrode membranes, and then rolling. The rolling process can be either cold rolling or hot rolling. A non-limiting example of a hot rolling temperature is 180°C.

[0158] In some embodiments, the solid-state battery may include an outer packaging. This outer packaging can be used to encapsulate the aforementioned solid-state battery cell.

[0159] In some embodiments, the outer packaging of a solid-state battery can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of a solid-state battery can also be a soft pack, such as a pouch-type soft pack. The material of the soft pack can be plastic; further, non-limiting examples of plastics may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0160] This application does not impose any particular limitation on the shape of the solid-state battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 shows a square solid-state battery cell 5 as an example.

[0161] In some embodiments, referring to FIG3, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. A solid-state battery cell 52 is encapsulated within the receiving cavity. The number of solid-state battery cells 52 contained in the solid-state battery cell 5 may be one or more, which can be selected by those skilled in the art according to actual needs.

[0162] Solid-state batteries can be battery device 4 or battery pack 1.

[0163] The battery device includes at least one solid-state battery cell. The number of solid-state battery cells in the battery device can be one or more, and those skilled in the art can select an appropriate number according to the application and capacity of the battery device.

[0164] Figure 4 shows a battery device 4 as an example. Referring to Figure 4, in the battery device 4, multiple solid-state battery cells 5 can be arranged sequentially along the length of the battery device 4. Of course, they can also be arranged in any other arbitrary manner. Furthermore, the multiple solid-state battery cells 5 can be fixed in place by fasteners.

[0165] Optionally, the battery device 4 may also include a housing with a receiving space in which a plurality of solid-state battery cells 5 are housed.

[0166] In some embodiments, the battery devices described above can also be assembled into a battery pack, and the number of battery devices contained in the battery pack can be one or more. Those skilled in the art can select an appropriate number according to the application and capacity of the battery pack.

[0167] Figures 5 and 6 illustrate a battery pack 1 as an example. Referring to Figures 5 and 6, the battery pack 1 may include a battery compartment and multiple battery devices 4 disposed within the battery compartment. The battery compartment includes an upper compartment 2 and a lower compartment 3, with the upper compartment 2 covering the lower compartment 3 to form a closed space for accommodating the battery devices 4. The multiple battery devices 4 can be arranged in any manner within the battery compartment.

[0168] Secondly, this application also provides a method for preparing a solid-state battery, which includes the following steps:

[0169] S1: Mix the positive electrode active material, sulfide electrolyte, binder and toughening fiber to obtain a mixture;

[0170] S2: Perform film-forming treatment on the mixture to obtain a positive electrode film;

[0171] S3: The positive electrode film is attached to at least one surface of the positive electrode current collector to obtain the positive electrode sheet;

[0172] S4: Assemble the positive electrode to obtain the solid-state battery;

[0173] The toughening fibers account for 0.1% to 3% of the weight of the positive electrode membrane.

[0174] In the solid-state battery preparation method provided in this application, by adding toughening fibers at a weight percentage of 0.1% to 3%, the binder can be fully fibrosed without prolonged high-speed rotation and high-shear action during the mixture preparation process. This not only reduces the occurrence of side reactions between the positive electrode active material and the sulfide electrolyte under localized high temperatures, but also reduces the problem of particle breakage of the positive electrode active material under prolonged shear action, thereby promoting the electrochemical performance of the positive electrode sheet and improving the first-time efficiency and capacity of the solid-state battery. In addition, the toughening fibers can synergistically work with the fibrous binder to jointly construct a fully three-dimensional network structure, providing strong support for the positive electrode active material and the sulfide electrolyte, thereby improving the mechanical properties of the positive electrode sheet and thus improving the cycle performance of the solid-state battery.

[0175] In some embodiments, the toughening fiber constitutes 0.1% to 3% by weight in the positive electrode membrane, for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, or any range of the above values. Therefore, using toughening fibers at this content can effectively shorten the mixing time during the preparation of the positive electrode membrane, improve the electrochemical performance of the positive electrode, and facilitate the improvement of mechanical properties.

[0176] In some embodiments, the toughening fibers constitute 0.5% to 2.5% of the weight of the positive electrode film. This results in particularly superior electrochemical and mechanical properties of the positive electrode, significantly improving the first-efficiency, capacity, and cycle performance of the solid-state battery. In some specific embodiments, the toughening fibers can constitute 1% to 2% of the weight of the positive electrode film.

[0177] In some embodiments, the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (50–88):(5–40):(0.1–3). As a non-limiting example, in the weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder, the value corresponding to the positive electrode active material can be 50, 55, 60, 65, 70, 75, 80, 85, or 88, or a range of any of the above values; the value corresponding to the sulfide electrolyte can be 5, 10, 15, 20, 25, 30, 35, or 40, or a range of any of the above values; the value corresponding to the binder can be 0.1, 0.5, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, or 3, or a range of any of the above values. Thus, the positive electrode active material and sulfide electrolyte are thoroughly mixed and form a continuous and effective ion transport channel, improving ion transport efficiency and thus optimizing electrochemical performance. At the same time, the binder at this weight ratio can improve the mechanical properties of the positive electrode sheet and reduce the loss of the battery's initial efficiency and capacity.

[0178] In some embodiments, the weight ratio of the positive electrode active material, sulfide electrolyte, and binder is (64–85):(10–30):(0.5–2.5). This further enhances the mechanical and electrochemical properties of the positive electrode, thereby improving the battery's initial efficiency, capacity, and cycle performance. In some specific embodiments, the weight ratio of the positive electrode active material, sulfide electrolyte, and binder can be (80–85):(10–15):(0.8–1.2).

[0179] In some embodiments, the positive electrode active material constitutes 50% to 88% of the weight of the positive electrode film, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 88%, or any range thereof. This improves ion transport efficiency and helps to enhance the battery's initial efficiency, capacity, and energy density. In some embodiments, the positive electrode active material constitutes 64% to 85% of the weight of the positive electrode film, and more specifically, 80% to 85%.

[0180] In some embodiments, the sulfide electrolyte constitutes 5% to 40% of the positive electrode membrane by weight, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, or any range thereof. This promotes uniform dispersion of the sulfide electrolyte in the positive electrode membrane, constructing a good ion transport network. In some embodiments, the sulfide electrolyte constitutes 10% to 30% of the positive electrode membrane by weight, more specifically, 10% to 15%.

[0181] In some embodiments, the binder constitutes 0.1% to 3% by weight in the positive electrode membrane, for example, 0.1%, 0.5%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%, or any range of the above values. This provides sufficient binder to offer a good fibrous network, effectively improving the mechanical properties of the positive electrode while maintaining its electrochemical performance, reducing the impact of binder on initial efficiency and capacity. In some embodiments, the binder constitutes 0.5% to 2.5% by weight in the positive electrode membrane, more specifically, 1% to 2%.

[0182] In some embodiments, the positive electrode active material, sulfide electrolyte, binder, and toughening fiber are mixed to meet the following conditions: mixing temperature of 45°C to 200°C, mixing speed of 1000 rpm to 6000 rpm, and mixing time of 5 min to 60 min. As a non-limiting example, the mixing temperature can be 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or any range of the above values; the mixing speed can be 1000 rpm, 2000 rpm, 3000 rpm, 4000 rpm, 5000 rpm, or 6000 rpm, or any range of the above values; and the mixing time can be 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, or 60 min, or any range of the above values. Therefore, the binder can be fiberized, so that it can form a more complete fiberized network with the toughening fibers in a shorter mixing time. This reduces the probability of side reactions between the positive electrode active material and the sulfide electrolyte at high temperatures, and also reduces the probability of particle breakage of the positive electrode active material, thereby improving the initial efficiency and capacity of the positive electrode sheet.

[0183] In this application, the unit "rpm" refers to revolutions per minute, and the unit "min" refers to minutes.

[0184] In some embodiments, the positive electrode active material, sulfide electrolyte, binder, and toughening fiber are mixed under the following conditions: mixing temperature of 60°C to 150°C, mixing speed of 2500 rpm to 5000 rpm, and mixing time of 10 min to 30 min. This further improves the initial efficiency and capacity of the positive electrode sheet, while also enhancing its mechanical properties.

[0185] In some embodiments, the mixture is subjected to a film-forming process, including the step of roll forming at a temperature of 45°C to 200°C to obtain a positive electrode film. As a non-limiting example, the roll forming temperature can be 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or a range of any of the above values. This allows the positive electrode film to be rolled thinned to obtain a suitable thickness and suitable loading capacity.

[0186] In some embodiments, attaching a positive electrode membrane to at least one surface of a positive electrode current collector includes the following steps: applying a primer to at least one surface of the positive electrode current collector to obtain a primer layer; covering the positive electrode membrane onto the primer layer; and performing a bonding treatment at a temperature of 45°C to 200°C to obtain a positive electrode sheet. As a non-limiting example, the bonding treatment temperature can be 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or a range of any of the above values. This improves the adhesion performance between the positive electrode membrane and the positive electrode current collector, thereby enhancing the structural stability of the positive electrode sheet.

[0187] Thirdly, this application also provides a positive electrode sheet. The positive electrode sheet includes a positive current collector and a positive electrode membrane disposed on at least one surface of the positive current collector. The positive electrode membrane includes a positive active material, a sulfide electrolyte, a binder, and toughening fibers.

[0188] The toughening fibers account for 0.1% to 3% of the weight of the positive electrode membrane.

[0189] In the positive electrode sheet provided in this application, toughening fibers are introduced into the positive electrode film at a weight percentage of 0.1% to 3%. This allows the positive electrode film to be prepared without prolonged high-speed rotation and high-shear action to promote sufficient fiberization of the binder. This not only reduces the occurrence of side reactions between the positive electrode active material and the sulfide electrolyte under local high temperatures, but also reduces the problem of particle breakage of the positive electrode active material under prolonged shear action, thereby promoting the electrochemical performance of the positive electrode sheet. In addition, the toughening fibers can synergistically work with the fiberized binder to jointly construct a fully developed three-dimensional network structure, providing strong support for the positive electrode active material and the sulfide electrolyte, thereby improving the mechanical properties of the positive electrode sheet. Using the positive electrode sheet provided in this application in solid-state batteries can effectively improve the initial efficiency and capacity of solid-state batteries, while also improving the cycle performance of solid-state batteries.

[0190] In some embodiments, the positive electrode is the same as the positive electrode in the aforementioned solid-state battery. This effectively improves the electrochemical and mechanical properties of the positive electrode.

[0191] Fourthly, this application also provides an electrical device. This electrical device includes at least one of the above-described solid-state battery, a solid-state battery prepared by the above-described solid-state battery preparation method, and the above-described positive electrode. Therefore, the electrochemical performance of the electrical device is improved.

[0192] In some embodiments, the electrical device includes at least one of the solid-state batteries of any of the embodiments provided in this application.

[0193] In a non-limiting sense, solid-state batteries can be used as a power source for electrical devices or as an energy storage unit for electrical devices. Electrical devices can include, but are not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Mobile devices can be, for example, mobile phones, laptops, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric motorcycles, power tools, etc., but are not limited to these. This electrical device can also be applied to military equipment, aerospace, and other fields, and can also be applied to energy storage power systems such as hydroelectric, thermal, wind, and solar power plants.

[0194] As an electrical device, solid-state batteries can be selected based on its usage requirements.

[0195] Figure 7 shows an example of an electrical device 6. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this electrical device for solid-state batteries, a battery device or battery pack can be used.

[0196] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a thin and light design and can use solid-state batteries as their power source.

[0197] The following describes some embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where the technology or conditions are not specified in the embodiments, they are performed according to the description above, or according to the technology or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially, or can be synthesized from commercially available products using conventional methods.

[0198] Example 1

[0199] 1) Preparation of the positive electrode sheet:

[0200] Take the positive electrode active material NCM 811 The composition includes: sulfide electrolyte LPSCl, conductive agent VGCF, binder PTFE, and cellulose fibers (diameter 20 μm, length 150 μm, aspect ratio 7.5, tensile strength 600 MPa, tensile modulus 15 GPa, specific surface area 250 m²). 2 The mixture was dispersed at high speed at a weight ratio of 83:13:2:1:1 at 80℃, 3000rpm, and 10min to obtain a uniform mixture. The mixture was then rolled at 80℃ to form a positive electrode film with a thickness of 100μm. The positive electrode film was then subjected to high-temperature treatment in a vacuum oven at 80℃ for 12 hours and bonded to an aluminum foil current collector coated with a primer at 80℃. Finally, the film was die-cut with a die size of 6cm×9.5cm to obtain the positive electrode sheet.

[0201] In this application, the unit "cm" refers to centimeters.

[0202] 2) Preparation of solid electrolyte sheets:

[0203] The sulfide electrolyte LPSCl and binder PTFE were mixed evenly at a weight ratio of 98:2, heated on a heating table at 80°C, and rolled back and forth until the thickness was 100μm. The solid electrolyte sheet was obtained by die-cutting with a die size of 6.5cm×9.8cm.

[0204] 3) Preparation of the negative electrode sheet:

[0205] Nano-silicon, graphite, VGCF (a conductive agent), and PVDF (a binder) were prepared in a weight ratio of 55:30:12:1:2. The PVDF binder was dissolved in NMP (an organic solvent), and then the nano-silicon and conductive agent were added and stirred to form a homogenized slurry with a solid content of 30%. The slurry was then uniformly coated onto both sides of a copper foil using a continuous coating method, with a coating width of 9.5 cm. After coating, the foil was dried at 80 °C and then rolled until the thickness reached 30 μm. Finally, the foil was die-cut using a die with a die size of 6.4 cm × 9.7 cm to obtain the negative electrode sheet.

[0206] 4) Fabrication of all-solid-state batteries:

[0207] The positive electrode, solid electrolyte sheet, and negative electrode are stacked in sequence and assembled in an alternating layering manner. They are then hot-pressed at 80°C and sealed with aluminum-plastic film under negative pressure to obtain a soft-pack all-solid-state battery.

[0208] As shown in Table 1 below, the pouch-pack all-solid-state batteries of Examples 2-18 and Comparative Examples 1-4 are prepared using methods similar to those of the pouch-pack all-solid-state battery of Example 1. The specific differences from Example 1 are as follows:

[0209] Example 2: The toughening fiber used was zirconia fiber (diameter 5μm, length 50μm, aspect ratio 10, tensile strength 700MPa, tensile modulus 125GPa, specific surface area 100m²). 2 / g);

[0210] Example 3: The toughening fiber used was glass fiber (diameter 2μm, length 2mm, aspect ratio 1000, tensile strength 125MPa, tensile modulus 20GPa, specific surface area 10m²). 2 / g);

[0211] Examples 4-11: The amounts of positive electrode active material, sulfide electrolyte, and toughening fiber are different;

[0212] Example 12: The positive electrode active material is lithium cobalt oxide (LiCoO2, LCO);

[0213] Example 13: The conductive agent used is carbon nanotubes (CNTs);

[0214] Example 14: LGPS was selected as the sulfide electrolyte;

[0215] Example 15: During the preparation of the positive electrode film, the mixing speed was 4500 rpm;

[0216] Example 16: During the preparation of the positive electrode film, the mixing temperature was 120°C;

[0217] Example 17: During the preparation of the positive electrode film, the mixing time was 20 min;

[0218] Example 18: During the preparation of the positive electrode film, the rolling temperature is 120°C;

[0219] Comparative Example 1: No toughening fibers were added to the positive electrode membrane;

[0220] Comparative Example 2: No toughening fibers were added to the positive electrode membrane, and the mixing time was extended to 90 min;

[0221] Comparative Example 3: No toughening fibers were added to the positive electrode membrane, and the mixing speed was increased to 8000 rpm;

[0222] Comparative Example 4: The amounts of positive electrode active material, sulfide electrolyte, and toughening fiber are different.

[0223] Table 1. Relevant parameters of the positive electrode film

[0224] Note: The weight ratio refers to the weight ratio of the positive electrode active material, sulfide electrolyte, conductive agent, binder and toughening fiber.

[0225] Test case

[0226] The following tests were conducted on the positive electrode sheets of Examples 1-18, Comparative Examples 1-4, and the pouch-type all-solid-state battery:

[0227] (1) Morphological characterization of the positive electrode film: The morphology of the positive electrode film was characterized by a field emission scanning electron microscope (SEM) of Hitachi SU8100. The results are shown in Figure 8.

[0228] (2) Tensile strength of positive electrode membrane: The positive electrode membrane was loaded at a stable speed of 5 mm / min using a tensile testing machine, and the maximum destructive load of the sample was recorded.

[0229] (3) Electrical performance of soft-pack all-solid-state battery: The charging cut-off voltage is 4.3 volts (V) and the discharging cut-off voltage is 2V. The first efficiency, discharge specific capacity and capacity retention rate of the all-solid-state battery are tested at a current of 0.1C rate and the test pressure is 50MPa.

[0230] The performance test results of Examples 1-18 and Comparative Examples 1-4 are shown in Table 2 below.

[0231] Table 2. Performance test results of the positive electrode film and battery

[0232] Figure 8 is a SEM image of the positive electrode membrane of Embodiment 1 of this application. Referring to Figure 8, cellulose fibers and the fibrillated binder PTFE jointly construct a three-dimensional network structure, which is the positive electrode active material NCM. 811 The sulfide electrolyte LPSCl provides strong support to reduce defects such as cracks or breakage during roll forming.

[0233] According to the test results in Table 2, the pouch-type all-solid-state batteries of Examples 1-18 achieved an initial efficiency of over 84.8%, a 0.1C discharge specific capacity of over 169.2 mAh / g, and a capacity retention rate of over 91.5% after 50 cycles at 0.1C. Furthermore, the initial efficiency, 0.1C discharge specific capacity, and 50-cycle capacity retention rate of the pouch-type all-solid-state batteries of Examples 1-18 were all higher than those of Comparative Examples 1-4, indicating that the introduction of toughening fibers can effectively improve the initial efficiency, capacity, and cycle performance of solid-state batteries. Simultaneously, the positive electrode films of Examples 1-18 exhibited high tensile strength, and no cracks or damage were observed after roll forming, which is beneficial for promoting the stable electrochemical performance of solid-state batteries.

[0234] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0235] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A solid-state battery, comprising a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film disposed on at least one surface of the positive current collector, the positive electrode film comprising a positive active material, a sulfide electrolyte, a binder and toughening fibers; The toughening fibers constitute 0.1% to 3% of the weight of the positive electrode membrane.

2. The solid-state battery according to claim 1, wherein, The toughening fibers constitute 0.5% to 2.5% of the weight of the positive electrode membrane.

3. The solid-state battery according to claim 1 or 2, wherein, The toughening fiber includes at least one of cellulose fiber, glass fiber, and zirconium oxide fiber.

4. The solid-state battery according to any one of claims 1 to 3, wherein, The toughening fiber satisfies at least one of the following conditions: (1) The length of the toughening fiber is 0.01 mm to 5 mm; (2) The diameter of the toughening fiber is 0.1 μm to 30 μm; (3) The aspect ratio of the toughening fiber is 2 to 1000; (4) The tensile strength of the toughening fiber is 50MPa to 1500MPa; (5) The tensile modulus of the toughening fiber is ≥200MPa; (6) The specific surface area of ​​the toughening fiber is ≥1m². 2 / g.

5. The solid-state battery according to any one of claims 1 to 4, wherein, The weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (50-88):(5-40):(0.1-3).

6. The solid-state battery according to claim 5, wherein, The weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (64-85):(10-30):(0.5-2.5).

7. The solid-state battery according to any one of claims 1 to 6, wherein, The positive electrode membrane satisfies at least one of the following conditions: (1) The positive electrode active material includes at least one of lithium phosphate with olivine structure and its modified compound and lithium transition metal oxide and its modified compound; (2) The sulfide electrolyte includes at least one of Thio-LISICON type solid electrolyte, Argyrodite type solid electrolyte and LGPS type solid electrolyte; (3) The adhesive includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, polyacrylate and polyurethane.

8. The solid-state battery according to any one of claims 1 to 7, wherein, The positive electrode film further includes a conductive agent, which satisfies at least one of the following conditions; (1) The conductive agent includes at least one of conductive carbon black, conductive graphite, acetylene black, carbon nanotubes, graphene and carbon fiber. (2) The conductive agent in the positive electrode film has a weight percentage of 0.5% to 4%.

9. The solid-state battery according to any one of claims 1 to 8, wherein, The thickness of the positive electrode film is 50 μm to 300 μm.

10. The solid-state battery according to any one of claims 1 to 9, wherein, The solid-state battery is an all-solid-state battery.

11. A method for preparing a solid-state battery, comprising the following steps: The positive electrode active material, sulfide electrolyte, binder and toughening fiber are mixed to obtain a mixture; The mixture is subjected to a film-forming process to obtain a positive electrode film; The positive electrode film is attached to at least one surface of the positive electrode current collector to obtain a positive electrode sheet; The positive electrode is assembled to obtain the solid-state battery; The toughening fibers constitute 0.1% to 3% of the weight of the positive electrode membrane.

12. The method for preparing a solid-state battery according to claim 11, wherein, The toughening fibers constitute 0.5% to 2.5% of the weight of the positive electrode membrane.

13. The method for preparing a solid-state battery according to claim 11 or 12, wherein, The weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (50-88):(5-40):(0.1-3).

14. The method for preparing a solid-state battery according to claim 13, wherein, The weight ratio of the positive electrode active material, the sulfide electrolyte, and the binder is (64-85):(10-30):(0.5-2.5).

15. The method for preparing a solid-state battery according to any one of claims 11 to 14, wherein, The positive electrode active material, sulfide electrolyte, binder, and toughening fiber are mixed to meet the following conditions: The mixing temperature is 45℃~200℃, the mixing speed is 1000rpm~6000rpm, and the mixing time is 5min~60min.

16. The method for preparing a solid-state battery according to claim 15, wherein, The positive electrode active material, sulfide electrolyte, binder, and toughening fiber are mixed to meet the following conditions: The mixing temperature is 60℃~150℃, the mixing speed is 2500rpm~5000rpm, and the mixing time is 10min~30min.

17. The method for preparing a solid-state battery according to any one of claims 11 to 16, wherein, The mixture is subjected to a film-forming treatment, including the following steps: The positive electrode film is obtained by rolling and forming the film at a temperature of 45℃~200℃.

18. A positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode membrane disposed on at least one surface of the positive current collector, the positive electrode membrane comprising a positive active material, a sulfide electrolyte, a binder and toughening fibers; The toughening fibers constitute 0.1% to 3% of the weight of the positive electrode membrane.

19. The positive electrode sheet according to claim 18, wherein, The positive electrode is the positive electrode in the solid-state battery according to any one of claims 2 to 10.

20. An electrical device comprising at least one of the following: a solid-state battery according to any one of claims 1 to 10; a solid-state battery prepared by the method of preparing a solid-state battery according to any one of claims 11 to 17; and a positive electrode sheet according to any one of claims 18 to 19.

Images