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

Abstract

This application provides a solid-state battery and its preparation method, a positive electrode sheet, and an electrical device. The solid-state battery includes a positive electrode sheet, which includes a positive current collector and a base coating layer disposed on at least one surface of the positive current collector. The base coating layer includes a polymer and a conductive agent in a weight ratio of (60-80):(20-40). The polymer has a chemical formula having repeating unit A and repeating unit B. Repeating unit A includes a polar polymer block, and the side groups of repeating unit B have a structure as shown in general formula (I). R includes C3-C6 branched alkyl groups, C3-C6 branched alkyl groups, and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The solid-state battery incorporates at least one of an aryl group and at least one C1-C3 alkyl group substituted with a C6-C8 aryl group. The polymer is introduced into the undercoat layer of the positive electrode. During the preparation of the undercoat layer, a low-polarity solvent can be used to replace the high-polarity solvent, reducing the residual amount of the high-polarity solvent and thus reducing the probability of degradation of the sulfide electrolyte. Therefore, the initial efficiency and capacity of the solid-state battery are effectively improved.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, and further to a solid-state battery and its preparation method, positive electrode sheet, and electrical device. Background Technology

[0002] 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 based on sulfide electrolytes, the poor chemical stability of sulfide electrolytes makes them prone to side reactions with highly polar solvents, resulting in less than ideal initial efficiency and capacity. Summary of the Invention

[0003] 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.

[0004] A first aspect of this application provides a solid-state battery comprising a positive electrode sheet, the positive electrode sheet including a positive current collector, and a base coating layer disposed on at least one surface of the positive current collector; the base coating layer comprises a polymer and a conductive agent in a weight ratio of (60-80):(20-40), the polymer having a chemical formula having repeating unit A and repeating unit B, the repeating unit A including a polar polymer block, and the side groups of the repeating unit B having a structure as shown in general formula (I):

[0005]

[0006] Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 groups substituted with at least one C6-C8 aryl group.

[0007] In the solid-state battery provided in this application, the bottom coating layer of the positive electrode includes a polymer, the chemical formula of which has repeating unit A and repeating unit B, and the side groups of repeating unit B are C3-C6 branched alkyl groups, C3-C6 branched alkyl groups, and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20Aryl groups and at least one C1-C3 group substituted with a C6-C8 aryl group, which are sterically hindered, can protect polar functional groups such as ester groups in the polymer, thereby regulating the polymer's polarity and promoting its dissolution in low-polarity solvents. Therefore, low-polarity solvents can be used to replace high-polarity solvents during the preparation of the undercoat layer, minimizing the residual amount of high-polarity solvents in the undercoat layer. This reduces the probability of degradation of chemically unstable components such as sulfide electrolytes under the action of high-polarity solvents, effectively improving the electrochemical performance of the positive electrode and thus enhancing the first-cycle efficiency and capacity of the solid-state battery. Simultaneously, repeating unit A includes polar polymer blocks, giving the polymer excellent adhesion. The polymer and conductivity are synergistically combined at a mass ratio of (60-80):(20-40), resulting in an undercoat layer that possesses both high adhesion and high conductivity. This improves the peel strength of the positive electrode and reduces its internal resistance, thereby enhancing the cycle stability of the solid-state battery.

[0008] In some embodiments, R includes at least one selected from tert-butyl, tert-amyl, isopropyl, triphenylmethyl, and adamantyl. Thus, the steric hindrance of the R group effectively protects polar functional groups such as ester groups, thereby promoting the dissolution of the polymer in low-polarity solvents.

[0009] In some embodiments, R includes a tert-butyl group. Thus, the R group has high steric hindrance, a simple structure, and is easy to remove, exposing polar functional groups with high adhesive strength, thereby improving the peel strength of the positive electrode sheet.

[0010] In some embodiments, the repeating unit B has a structure as shown in general formula (II):

[0011]

[0012] Where n is selected from positive integers. Therefore, the content of the side group -COOR in the polymer can be adjusted, thereby regulating the polymer's polarity and promoting its dissolution in low-polarity solvents.

[0013] In some embodiments, the repeating unit A includes at least one selected from polyacrylic acid blocks, polytetrafluoroethylene blocks, polyvinylidene fluoride blocks, and polyurethane blocks. Thus, the repeating unit A contains highly adhesive polar functional groups, which can improve the peel strength of the positive electrode, reduce the internal resistance of the positive electrode, and thereby enhance the cycle stability of the solid-state battery.

[0014] In some embodiments, the molar ratio of repeating unit A to repeating unit B is (1-10):1. Therefore, by adjusting the molar ratio of repeating unit A to repeating unit B, the polymer can achieve high adhesion while maintaining solubility in low-polarity solvents, thereby reducing the use of high-polarity solvents and lowering the probability of degradation of substances such as sulfide electrolytes, thus improving the electrochemical performance of the positive electrode.

[0015] In some embodiments, the number-average molecular weight of the polymer is 20,000 to 500,000. This improves the adhesive strength of the polymer while maintaining good mechanical strength and chemical stability, thereby improving the peel strength and structural stability of the positive electrode sheet.

[0016] In some embodiments, the weight ratio of the polymer to the conductive agent is (60-65):(35-40). This results in excellent adhesive strength of the undercoat layer while maintaining good conductivity, thereby improving the peel strength and electrochemical performance of the positive electrode.

[0017] 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 in the undercoat layer, reducing the internal resistance of the positive electrode.

[0018] In some embodiments, the primer layer further includes a first solvent at a weight percentage of 0.01% to 0.1%, wherein the first solvent satisfies at least one of the following conditions: (1) dielectric constant ≤ 3, (2) dipole moment ≤ 7 × 10⁻⁶. - 30 C·m, (3) Polarization index ≤1. Therefore, a low-polarity first solvent can be used to dissolve the polymer, reducing the use of high-polarity solvents, resulting in a small amount of first solvent remaining in the primer layer, while the amount of high-polarity solvent residue is greatly reduced.

[0019] In some embodiments, the first solvent includes at least one selected from toluene, xylene, n-heptane, n-hexane, anisole, n-butyl ether, and butyl butyrate. Therefore, the first solvent has low polarity, which reduces the probability of side reactions occurring with substances such as sulfide electrolytes.

[0020] In some embodiments, the thickness of the undercoat is 0.5 μm to 10 μm. Thus, the undercoat can provide high adhesion while reducing the internal resistance of the positive electrode, resulting in a positive electrode that possesses both excellent adhesive strength and electrochemical performance.

[0021] In some embodiments, the positive electrode further includes a positive active layer disposed on the surface of the undercoat layer away from the positive current collector, and the positive active layer comprises a sulfide electrolyte. Thus, the sulfide electrolyte can enhance the ion conductivity of the positive active layer and reduce interfacial impedance, promoting the charge transfer efficiency and full capacity release of the positive active material. Simultaneously, the extremely low residual amount of highly polar solvent in the positive electrode reduces the probability of side reactions of the sulfide electrolyte, thereby optimizing the electrochemical performance of the positive electrode.

[0022] In some embodiments, the solid-state battery is an all-solid-state battery. This further enhances the safety performance of the solid-state battery.

[0023] A second aspect of this application provides a method for preparing a solid-state battery, which includes the following steps:

[0024] A positive electrode sheet is prepared by forming an undercoat layer on at least one surface of a positive current collector using a polymer and a conductive agent.

[0025] The weight ratio of the polymer to the conductive agent is (60-80):(20-40);

[0026] The positive electrode sheet is assembled to obtain a solid-state battery;

[0027] The polymer has a chemical formula having repeating unit A and repeating unit B, wherein repeating unit A comprises a polar polymer block, and the side groups of repeating unit B have a structure as shown in general formula (I):

[0028]

[0029] Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 groups substituted with at least one C6-C8 aryl group.

[0030] In the solid-state battery preparation method provided in this application, a bottom coating layer in the positive electrode sheet is prepared using a polymer. The polymer has a repeating unit A and a repeating unit B, and the side groups of the repeating unit B are C3-C6 branched alkyl groups and C3-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20Aryl groups and at least one C1-C3 group substituted with a C6-C8 aryl group, which are sterically hindered, can protect polar functional groups such as ester groups in the polymer, thereby regulating the polymer's polarity and promoting its dissolution in low-polarity solvents. Therefore, low-polarity solvents can be used to replace high-polarity solvents during the preparation of the undercoat layer, minimizing the residual amount of high-polarity solvents in the undercoat layer. This reduces the probability of degradation of chemically unstable components such as sulfide electrolytes under the action of high-polarity solvents, effectively improving the electrochemical performance of the positive electrode and thus enhancing the first-cycle efficiency and capacity of the solid-state battery. Simultaneously, repeating unit A includes polar polymer blocks, giving the polymer excellent adhesion. The polymer and conductivity are synergistically combined at a mass ratio of (60-80):(20-40), resulting in an undercoat layer that possesses both high adhesion and high conductivity. This improves the peel strength of the positive electrode and reduces its internal resistance, thereby enhancing the cycle stability of the solid-state battery.

[0031] In some embodiments, R includes at least one selected from tert-butyl, tert-amyl, isopropyl, triphenylmethyl, and adamantyl. Thus, the steric hindrance of the R group effectively protects polar functional groups such as ester groups, thereby promoting the dissolution of the polymer in low-polarity solvents.

[0032] In some embodiments, the polymer block A includes at least one selected from polyacrylic acid block, polytetrafluoroethylene block, polyvinylidene fluoride block, and polyurethane block. Thus, the repeating unit A contains highly adhesive polar functional groups, which can improve the peel strength of the positive electrode, reduce the internal resistance of the positive electrode, and thereby enhance the cycle stability of the solid-state battery.

[0033] In some embodiments, the method for preparing the primer layer includes the following steps:

[0034] The precursor is dissolved in the first solvent, and the conductive agent is added to obtain the primer adhesive;

[0035] The primer is applied to at least one surface of the positive electrode current collector to obtain a liquid film.

[0036] The precursor in the liquid film is pyrolyzed by heat treatment to form the polymer, thereby obtaining the base coating layer;

[0037] The precursor includes at least one of polytert-butyl acrylate and polytetrafluoroethylene-polytert-butyl acrylate block copolymer; the first solvent satisfies at least one of the following conditions: (1) dielectric constant ≤ 3, (2) dipole moment ≤ 7 × 10⁻⁶. -30 C·m,(3)Polarization index≤1.

[0038] Therefore, the precursor has tert-butyl acrylate functional groups as side groups. The tert-butyl group in these side groups, being a sterically hindered nonpolar functional group, can protect the polar functional groups in the precursor, regulate the precursor's polarity, and promote its dissolution in a low-polarity first solvent. Through coating and pyrolysis, some of the nonpolar functional groups in the precursor can be removed, exposing highly adhesive polar functional groups, while some nonpolar functional groups are retained, forming a polymer with repeating units A and B. Using this method to prepare the primer layer can, on the one hand, reduce the use and residue of highly polar solvents, effectively reducing the probability of side reactions between highly polar solvents and sulfide electrolytes, thereby improving the electrochemical performance of the positive electrode. On the other hand, it can improve the adhesion of the primer layer, giving the positive electrode higher peel strength, thus improving the internal resistance of the positive electrode.

[0039] In some embodiments, the first solvent comprises 85% to 98% by weight in the primer adhesive. This allows the precursor to dissolve sufficiently in the first solvent, which is beneficial for improving the uniformity of the distribution of the pyrolysis-formed polymer in the primer adhesive layer, thereby enhancing the peel strength and electrochemical performance of the positive electrode sheet.

[0040] 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 in the undercoat layer, reducing the internal resistance of the positive electrode.

[0041] In some embodiments, the weight ratio of the precursor to the conductive agent is (60-80):(20-40). This results in excellent adhesive strength of the undercoat layer while maintaining good conductivity, thereby improving the peel strength and electrochemical performance of the positive electrode.

[0042] In some embodiments, the heat treatment meets the following conditions: heating temperature of 80℃ to 200℃ and heating time of 12h to 24h. This results in excellent adhesive strength of the undercoat layer while maintaining good conductivity, thereby improving the peel strength and electrochemical performance of the positive electrode sheet.

[0043] In some embodiments, the heat treatment satisfies the following conditions: a heating temperature of 150°C to 200°C and a heating time of 15 to 20 hours. Therefore, the higher heating temperature increases the pyrolysis rate of non-polar functional groups, resulting in a higher proportion of repeating unit A formed by pyrolysis, thereby improving the polymer's adhesive strength and the peel strength of the positive electrode sheet.

[0044] A third aspect of this application provides a positive electrode sheet. The positive electrode sheet includes a positive current collector and a base coat layer disposed on at least one surface of the positive current collector; the base coat layer includes a polymer and a conductive agent in a weight ratio of (60-80):(20-40), the polymer having a chemical formula having repeating unit A and repeating unit B, the repeating unit A including a polar polymer block, and the side groups of the repeating unit B having a structure as shown in general formula (I):

[0045]

[0046] Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 groups substituted with at least one C6-C8 aryl group.

[0047] In the positive electrode sheet provided in this application, the bottom coating adhesive layer includes a polymer, the chemical formula of which has repeating unit A and repeating unit B, and the side groups of repeating unit B are C3-C6 branched alkyl groups, C3-C6 branched alkyl groups, and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 Aryl groups and at least one C1-C3 group substituted with a C6-C8 aryl group, which are sterically hindered, can protect polar functional groups such as ester groups in the polymer, thereby regulating the polymer's polarity and promoting its solubility in low-polarity solvents. Therefore, low-polarity solvents can be used to replace high-polarity solvents in the preparation of the primer layer, minimizing the residual amount of high-polarity solvents in the primer layer. This reduces the probability of degradation of chemically unstable components such as sulfide electrolytes under the action of high-polarity solvents, thus effectively improving the electrochemical performance of the positive electrode. Simultaneously, repeating unit A includes polar polymer blocks, giving the polymer excellent adhesion. The polymer and conductivity are synergistically combined at a mass ratio of (60-80):(20-40), resulting in a primer layer that possesses both high adhesion and high conductivity. This is beneficial for improving the peel strength of the positive electrode and reducing its internal resistance. 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.

[0048] In some embodiments, the positive electrode is the same as the positive electrode in the aforementioned solid-state battery. This effectively improves the peel strength and electrochemical performance of the positive electrode.

[0049] 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

[0050] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0051] Figure 1 This is a schematic diagram of a solid-state battery cell according to one embodiment of this application.

[0052] Figure 2 for Figure 1 An exploded view of a solid-state battery cell according to an embodiment of this application is shown.

[0053] Figure 3 This is a schematic diagram of a battery device according to one embodiment of this application.

[0054] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0055] Figure 5 for Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0056] Figure 6 This is a schematic diagram of an electrical device that uses a solid-state battery as a power source according to one embodiment of this application.

[0057] Figure 7 This is the infrared spectrum of the polymer of Example 1 of this application.

[0058] Explanation of reference numerals in the attached figures:

[0059] 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery assembly; 5. Solid-state battery cell; 51. Housing; 52. Solid-state battery cell; 53. Cover plate; 6. Electrical device. Detailed Implementation

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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".

[0064] 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.

[0065] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0066] 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.

[0067] 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.

[0068] 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."

[0069] 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.

[0070] 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."

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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℃.

[0079] 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.

[0080] 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.

[0081] In the fabrication of solid-state batteries, the preparation processes for the positive electrode active layer mainly 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 each component particle to obtain the positive electrode active layer. However, traditional solvent systems are highly polar solvents, such as N-methylpyrrolidone (NMP) or deionized water. In solid-state batteries based on sulfide electrolytes, the sulfide electrolyte has poor chemical stability and is prone to side reactions with highly polar solvents, leading to performance degradation. Therefore, a solvent-free dry process is more suitable for preparing the positive electrode active layer of solid-state batteries.

[0082] However, the adhesion between the positive electrode active layer and the positive electrode current collector prepared by the dry process is poor, causing the positive electrode active layer to easily detach or peel off from the positive electrode current collector. Therefore, a primer layer needs to be applied to the positive electrode current collector. This primer layer can be bonded to the positive electrode active layer in a softened state at high temperature. After the primer layer cools, it can provide sufficient adhesion to tightly bond the positive electrode active layer and the positive electrode current collector.

[0083] The primer layer is typically prepared by dissolving the binder in a solvent to obtain a primer solution; the primer solution is then applied to the positive electrode current collector to form the primer layer. Currently, primer solution formulations can be broadly categorized into aqueous and oil-based systems: aqueous systems primarily use water as the solvent and polymethyl methacrylate (PMA) as the binder; oil-based systems primarily use N-methylpyrrolidone (NMP) as the solvent and polyvinylidene fluoride (PVDF) as the binder. However, both water and NMP are highly polar solvents, so a small amount of these highly polar solvents often remains in the primer layer. After bonding with the positive electrode active layer, these solvents can react with the sulfide electrolyte, reducing the electrochemical performance of the positive electrode and resulting in less than ideal initial efficiency and capacity of the battery.

[0084] Furthermore, during the preparation of the primer adhesive, replacing high-polarity binders such as PMA and PVDF with low-polarity binders allows the use of low-polarity solvents to dissolve them, thus minimizing the residue of high-polarity solvents in the primer layer. However, low-polarity binders have poor adhesion, which is detrimental to the bonding between the positive electrode active layer and the positive electrode current collector. Therefore, how to reduce the residual amount of high-polarity solvents in the primer layer while maintaining excellent adhesion is a crucial problem that urgently needs to be solved in the field of solid-state batteries.

[0085] In view of this, 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.

[0086] One embodiment of this application provides a solid-state battery, which includes a positive electrode sheet, a positive current collector, and a base coat adhesive layer disposed on at least one surface of the positive current collector; the base coat adhesive layer includes a polymer and a conductive agent in a weight ratio of (60-80):(20-40), the polymer having a chemical formula having repeating unit A and repeating unit B, repeating unit A including a polar polymer block, and the side groups of repeating unit B having a structure as shown in general formula (I):

[0087]

[0088] Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 alkyl groups substituted with at least one C6-C8 aryl group.

[0089] In this application, "solid-state battery" refers to a battery in which the electrolyte includes a solid electrolyte; typically, a solid-state battery includes a positive electrode, a solid electrolyte sheet, and a negative electrode. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrode sheets. The solid electrolyte sheet acts as a conductor of ions between the positive and negative electrode sheets and also isolates them, thus preventing short circuits. Therefore, solid-state batteries do not require the separator found in traditional lithium-ion 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 improved safety, solid-state batteries are better suited for high-energy-density positive and negative electrode materials and reduce system weight, which is beneficial for achieving higher energy density.

[0090] In this application, "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.

[0091] In this application, "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.

[0092] In this application, "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.

[0093] In this application, "*" indicates a connection site.

[0094] In this application, "alkyl" refers to a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing this term, such as "C1-C6 alkyl," refer to alkyl groups containing 1 to 6 carbon atoms, and each occurrence can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, or C6 alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -C H(CH3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl -1-Butyl(-CH2CH2CH(CH3)2), 2-Methyl-1-Butyl(-CH2CH(CH3)CH2CH3), 1-Hexyl(-CH2CH2CH2CH2CH2CH3), 2-Hexyl(-CH(CH3)CH2CH2CH2CH3), 3-Hexyl(-CH(CH2CH3)(CH2CH2CH3)), 2-Methyl-2-pentyl(-C(CH3)2CH2CH2CH3), 3-Methyl-2-pentyl( -CH(CH3)CH(CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2) and 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3, etc.

[0095] In this application, "branched alkyl" refers to an alkyl group having at least one branch, which can be a saturated hydrocarbon containing a secondary carbon atom, a tertiary carbon atom, a quaternary carbon atom, or a combination thereof. Phrases containing this term, such as "C3-C6 branched alkyl," refer to a branched alkyl group containing 3 to 6 carbon atoms, and each occurrence can independently be a C3 branched alkyl, C4 branched alkyl, C5 branched alkyl, or C6 branched alkyl. Suitable examples include, but are not limited to, isopropyl (-CH(CH3)2), isobutyl (-CH2CH(CH3)2), sec-butyl (-CH(CH3)CH2CH3), tert-butyl (-C(CH3)3), and tert-pentyl (-C(CH3)2CH2CH3), etc.

[0096] In this application, "cycloalkyl" refers to a non-aromatic hydrocarbon containing a ring carbon atom, which can be a monocycloalkyl, spirocycloalkyl, or bridged cycloalkyl. Phrases containing this term include, for example, "C3-C6..." 10 "Cycloalkyl" refers to a cycloalkyl group containing 3 to 10 carbon atoms. Each time it appears, it can independently be C3 cycloalkyl, C4 cycloalkyl, C5 cycloalkyl, C6 cycloalkyl, C7 cycloalkyl, C8 cycloalkyl, C9 cycloalkyl, or C6 cycloalkyl. 10 Cycloalkyl. Suitable examples include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and adamantyl. Additionally, "cycloalkyl" may contain one or more double bonds; representative examples of cycloalkyl groups containing double bonds include cyclopentenyl, cyclohexenyl, cyclohexadienyl, and cyclobutadienyl.

[0097] In this application, "aryl" refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing one hydrogen atom. It can be a monocyclic aryl, a fused-ring aryl, or a polycyclic aryl. For polycyclic compounds, at least one is an aromatic ring system. For example, "C6~C6..." 20 "Aryl" refers to an aryl group containing 6 to 20 carbon atoms. Each time it appears, it can independently be a C6 aryl, C6 aryl, C6 aryl, or C6 aryl. 10 Aryl, C 14 Aryl, C 18 Aryl or C 20 Aryl groups. Suitable examples include, but are not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene, dinaphthalene, triphenylene and their derivatives.

[0098] In this application, "aryl-substituted alkyl" means an alkyl group in which at least one hydrogen atom is substituted by an aryl group. For example, "at least one C6-C8 aryl-substituted C1-C3 alkyl" means an alkyl group comprising 1-3 carbon atoms, wherein at least one hydrogen atom is substituted by a C6-C8 aryl group. Suitable examples include, but are not limited to, benzyl (phenylmethyl), phenethyl, diphenylmethyl, and triphenylmethyl.

[0099] In the solid-state battery provided in this application, the bottom coating layer of the positive electrode includes a polymer with repeating unit A and repeating unit B in its chemical formula. The side groups of repeating unit B are non-polar functional groups with high steric hindrance, such as C3-C6 branched alkyl groups, which can protect the polar functional groups such as ester groups in the polymer, thereby regulating polarity and promoting the dissolution of the polymer in low-polarity solvents. Therefore, low-polarity solvents can be used to replace high-polarity solvents during the preparation of the bottom coating layer, thus minimizing the residual amount of high-polarity solvents in the bottom coating layer. This reduces the probability of side reactions between the sulfide electrolyte and other components in the positive electrode and the high-polarity solvent, effectively improving the electrochemical performance of the positive electrode and increasing the initial efficiency and capacity of the solid-state battery. Meanwhile, the repeating unit A includes a polar polymer block, which makes the polymer exhibit excellent adhesion. The polymer and the conductivity are synergistically combined at a mass ratio of (60-80):(20-40), so that the undercoat has both high adhesion and high conductivity. This is beneficial to increase the peel strength of the positive electrode sheet, reduce the internal resistance of the positive electrode sheet, and thus improve the cycle stability of the solid-state battery.

[0100] The following is a description of polymers.

[0101] In some embodiments, R includes tert-butyl (-C(CH3)3), tert-pentyl (-C(CH3)2CH2CH3), isopropyl (-CH(CH3)2), triphenylmethyl and adamantyl At least one of them. Therefore, the large steric hindrance of the R group can effectively protect polar functional groups such as ester groups, thereby promoting the dissolution of the polymer in low polar solvents.

[0102] In some embodiments, R includes a tert-butyl group. Thus, the R group has high steric hindrance, a simple structure, and is easy to remove, exposing polar functional groups with high adhesive strength, thereby improving the peeling force of the positive electrode sheet.

[0103] In some embodiments, the repeating unit B has a structure as shown in general formula (II):

[0104]

[0105] Where n is selected from positive integers, representing the degree of polymerization of repeating unit B. As an example, n can take values ​​from 1 to 10000, such as 1, 100, 200, 500, 800, 1000, 2000, 5000, 8000, or 10000, or any range of the above values. Therefore, the content of the side group -COOR in the polymer can be adjusted, thereby regulating the polymer's polarity and promoting its solubility in low-polarity solvents.

[0106] In some embodiments, repeating unit A includes at least one selected from polyacrylic acid block, polytetrafluoroethylene block, polyvinylidene fluoride block, and polyurethane block. It is understood that repeating unit A may be selected from one of the aforementioned polymer blocks, or from a combination of at least two of the aforementioned polymer blocks. Thus, repeating unit A contains highly adhesive polar functional groups, which can improve the peel strength of the positive electrode, improve the internal resistance of the positive electrode, and thereby enhance the cycle stability of the solid-state battery.

[0107] In some embodiments, repeating unit A includes at least a polyacrylic acid block. It is understood that the R group in repeating unit B can be removed under suitable conditions, such as by pyrolysis under heating conditions, exposing highly polar carboxylic acid functional groups to form the polyacrylic acid block in repeating unit A, thereby providing high adhesion. In other embodiments, repeating unit A may also include at least one of a polytetrafluoroethylene block, a polyvinylidene fluoride block, and a polyurethane block, for example, a combination of a polyacrylic acid block and a polytetrafluoroethylene block.

[0108] In some embodiments, the molar ratio of repeating unit A to repeating unit B is (1–10):1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1, or any range of the above values. Further, the molar ratio of repeating unit A to repeating unit B can be (1–3):1. Therefore, by adjusting the molar ratio of repeating unit A to repeating unit B, the polymer can achieve high adhesion while maintaining solubility in low-polarity solvents, thereby reducing the use of high-polarity solvents, lowering the probability of degradation of substances such as sulfide electrolytes, and thus improving the electrochemical performance of the positive electrode.

[0109] In some embodiments, the number-average molecular weight of the polymer is between 20,000 and 500,000, for example, it can be 20,000, 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, or 500,000, or any range of the above values. Further, the number-average molecular weight of the polymer can be between 100,000 and 200,000. This improves the adhesive strength of the polymer while maintaining good mechanical strength and chemical stability, thereby improving the peel strength and mechanical properties of the positive electrode sheet.

[0110] The following is a description of the positive electrode sheet.

[0111] In some embodiments, the positive electrode includes a positive current collector, a positive active layer disposed on at least one surface of the positive current collector, and a primer layer disposed between the positive current collector and the positive active layer. The primer layer comprises a polymer and a conductive agent in a weight ratio of (60-80):(20-40). Therefore, using a polymer as a binder in the primer layer can, on the one hand, improve the adhesion of the primer layer and enhance the bonding strength between the positive current collector and the positive active layer, thereby improving the internal resistance of the positive electrode. On the other hand, it can reduce the residual amount of highly polar solvents in the primer layer, thus reducing the probability of side reactions of components such as sulfide electrolytes, thereby improving the electrochemical performance of the positive electrode.

[0112] Understandably, the polymer provided in this application can be used not only as a binder in the primer layer, but also as a positive electrode binder in the positive electrode active layer in some specific embodiments. If the polymer provided in this application is used as the positive electrode binder in the positive electrode active layer, the positive electrode active layer can be prepared using either a dry or wet process. This is because the polymer has good solubility in low-polarity solvents, and low-polarity solvents can be used to formulate the positive electrode slurry during the preparation of the positive electrode active layer, thereby reducing the negative impact on components with poor chemical stability, such as sulfide electrolytes. Furthermore, if the positive electrode active layer is prepared using a wet process, after the low-polarity solvent in the positive electrode slurry evaporates, the polymer can precipitate between the component particles of the positive electrode slurry and between the component particles and the positive electrode current collector, thereby tightly bonding the positive electrode active layer and the positive electrode current collector.

[0113] As a non-limiting example, the positive current collector has two surfaces opposite each other in its own thickness direction, the undercoat layer is disposed on either or both of the two opposite surfaces of the positive current collector, and the positive active layer is disposed on the surface of the undercoat layer away from the positive current collector.

[0114] 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).

[0115] In some embodiments, the conductive agent in the undercoat layer 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 in the undercoat layer may include at least one selected from SP, KS-6, acetylene black, vapor-grown carbon fibers (VGCF), carbon nanotubes (CNTs), and graphene. In some specific embodiments, the conductive agent in the undercoat layer may include at least one selected from conductive carbon black SP and carbon nanotubes (CNTs). This allows for the formation of continuous electron transport channels in the undercoat layer, reducing the internal resistance of the positive electrode and thereby improving the battery's initial efficiency, capacity, and energy density.

[0116] In some embodiments, the weight ratio of polymer to conductive agent in the primer layer is (60-80):(20-40), for example, 60:40, 65:35, 65:35, 70:30, 75:25, or 80:20, or any range of the above values. In some specific embodiments, the weight ratio of polymer to conductive agent in the primer layer can be (60-65):(35-40). Therefore, the primer layer exhibits excellent adhesive strength while maintaining good conductivity, thereby improving the peel strength and electrochemical performance of the positive electrode.

[0117] In some embodiments, the primer layer further includes a first solvent at a weight percentage of 0.01% to 0.1%, wherein the first solvent satisfies at least one of the following conditions: (1) dielectric constant ≤ 3, (2) dipole moment ≤ 7 × 10⁻⁶. -30 C·m,(3)Polarization index≤1.

[0118] In this application, dielectric constant, dipole moment, and polarization index are all well-known terms in the art, used to characterize the polarity of a solvent, and can be obtained from reference books such as Material Safety Data Sheets (MSDS). A higher dielectric constant indicates higher solvent polarity; a higher dipole moment indicates higher solvent polarity; and a higher polarization index indicates higher solvent polarity. At least one of the dielectric constant, dipole moment, and polarization index of the first solvent satisfies the above conditions, and it is typically a low-polarity solvent. As an example, the weight percentage of the first solvent in the primer layer can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%, or a range of any of the above values. Further, the weight percentage of the first solvent in the primer layer can be from 0.01% to 0.05%. Therefore, a low-polarity first solvent can be used to dissolve the polymer, reducing the use of high-polarity solvents. This results in a small amount of first solvent remaining in the primer layer, while the amount of high-polarity solvent residue is greatly reduced.

[0119] In some embodiments, the first solvent includes at least one selected from toluene, xylene, n-heptane, n-hexane, anisole, n-butyl ether, and butyl butyrate. In some specific embodiments, the first solvent may include xylene. Therefore, the first solvent has low polarity, which can reduce the probability of side reactions occurring in substances such as sulfide electrolytes.

[0120] In some specific embodiments, the primer layer may further include a second solvent at a weight ratio of ≤0.05%, wherein the second solvent satisfies at least one of the following conditions: (1) dielectric constant ≥3.6, (2) dipole moment ≥8×10⁻⁶. -30 C·m, (3) Polarization index ≥1.5. As an example, the weight percentage of the second solvent in the primer layer can be 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, or 0.05%, or a range of any of the above values. Further, the weight percentage of the second solvent in the primer layer is ≤0.01%. Thus, the residual amount of high polarity solvent in the primer layer is extremely low, or even non-existent, effectively reducing side reactions between high polarity solvent and sulfide electrolytes, thereby improving the electrochemical performance of the positive electrode.

[0121] In some embodiments, the thickness of the undercoat is 0.5 μm to 10 μm, for example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, or any range of the above values. Therefore, the undercoat can provide high adhesion while reducing the internal resistance of the positive electrode, resulting in a positive electrode that possesses both excellent adhesive strength and electrochemical performance.

[0122] In some embodiments, the positive electrode active layer includes a positive electrode active material. The positive electrode active material may be any positive electrode active material known in the art for use in batteries. As a non-limiting example, the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Non-limiting examples of lithium-containing phosphates with an olivine structure may 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 may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, 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 0.05O2. In some embodiments, the positive electrode active material includes at least one of 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 further may include lithium nickel cobalt manganese oxide (NCM). Thus, the solid-state battery has excellent initial efficiency, capacity, and energy density.

[0123] In some embodiments, the weight percentage of the positive electrode active material in the positive electrode active layer is 50% - 88%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 88%, or can be a range composed of any of the above values. In some specific embodiments, the weight percentage of the positive electrode active material in the positive electrode active layer can be 80% - 85%. Thus, the ion transport efficiency can be improved, and it is beneficial to enhance the initial efficiency, capacity, and energy density of the battery.

[0124] In some embodiments, the positive electrode active layer further includes a sulfide electrolyte.

[0125] In the present application, the "sulfide electrolyte" in the positive electrode active layer refers to a sulfide-based solid electrolyte. The sulfide electrolyte can enhance the ion conduction ability of the positive electrode active layer, reduce the interfacial impedance, and promote the charge transfer efficiency between the positive electrode active material and the outside and the full release of its capacity. At the same time, the residual amount of the high-polarity solvent in the positive electrode sheet is extremely low, which can reduce the probability of side reactions of the sulfide electrolyte, thereby optimizing the electrochemical performance of the positive electrode sheet.

[0126] In some embodiments, the sulfide electrolyte in the positive electrode active layer includes at least one of Thio-LISICON type solid electrolyte, Argyrodite (sulfur silver germanite) type solid electrolyte, and LGPS (lithium germanium phosphorus sulfur) type solid electrolyte. However, the present application is not limited to these materials, and other traditional 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 structures of these sulfides can be at least one of glassy state, glass-ceramic state, and crystalline state. Among them, the expression of the 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 Li6PS5X and Li 5.5 PS5.5 X 1.5 X includes at least one of Cl, Br, and I, for example, it may include Li6PS5Cl and Li 5.5 PS 5.5 Cl 1.5 LGPS type solid electrolytes may include Li 10 GeP2S 12 In some specific embodiments, the sulfide electrolyte in the positive electrode active layer may include Li6PS5Cl (which can be abbreviated as LPSCl) and Li 10 GeP2S 12 At least one of (which can be abbreviated as LGPS). As a result, the electrical performance of solid-state batteries is improved.

[0127] In some embodiments, the weight percentage of the sulfide electrolyte in the positive electrode active layer is 5% to 40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, or any range of the above values. In some specific embodiments, the weight percentage of the sulfide electrolyte in the positive electrode active layer can be 10% to 15%. This promotes uniform dispersion of the sulfide electrolyte in the positive electrode active layer, constructing a good ion transport network.

[0128] In some embodiments, the positive electrode active layer further includes a positive electrode binder. The positive electrode binder may include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, polyacrylate, polyurethane, and at least one of the above polymers. In some specific embodiments, the binder may include polytetrafluoroethylene (PTFE). Therefore, the positive electrode binder can provide excellent adhesion in both dry and wet processes, improving the mechanical properties of the positive electrode active layer.

[0129] In some embodiments, the weight percentage of the positive electrode binder in the positive electrode active layer is 0.1% to 3%, for example, it 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 any range of the above values. In some specific embodiments, the weight percentage of the positive electrode binder in the positive electrode active layer can be 1% to 2%. This effectively improves the mechanical properties of the positive electrode sheet while also maintaining its electrochemical performance, reducing the impact of the positive electrode binder on initial efficiency and capacity.

[0130] In some embodiments, the positive electrode active layer also includes a positive electrode conductive agent. This can improve the electronic conductivity of the positive electrode active layer, reduce the internal resistance of the positive electrode sheet, and thus improve the battery's initial efficiency, capacity, and energy density.

[0131] In some embodiments, the positive electrode 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 positive electrode conductive agent may include at least one selected from SP, KS-6, acetylene black, vapor-grown carbon fibers (VGCF), carbon nanotubes (CNTs), and graphene. In some specific embodiments, the positive electrode conductive agent may include vapor-grown carbon fibers (VGCF). This allows for the formation of continuous electron transport channels in the positive electrode active layer, reducing the internal resistance of the positive electrode active layer.

[0132] In some embodiments, the weight percentage of the positive electrode conductive agent in the positive electrode active layer is 0.5% to 4%, for example, it can be 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. In some specific embodiments, the weight percentage of the positive electrode conductive agent in the positive electrode active layer is 1% to 3%. Therefore, the conductive agent can construct a relatively complete electron transport network in the positive electrode active layer, optimize electron conduction performance, and improve the battery capacity and energy density.

[0133] In some embodiments, the positive electrode active layer may also include toughening fibers. This effectively shortens the mixing time for preparing the positive electrode active layer using the dry process, reduces side reactions and particle breakage of the positive electrode active material, and promotes the electrochemical performance of the positive electrode sheet. Simultaneously, the toughening fibers can synergistically enhance the mechanical properties of the positive electrode active layer in conjunction with the fibrous positive electrode binder.

[0134] In some embodiments, the toughening fiber includes at least one selected from cellulose fiber, glass fiber, and zirconium oxide fiber. In some specific embodiments, the toughening fiber may include cellulose fiber. Therefore, the aforementioned 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 active layer.

[0135] In some embodiments, the toughening fiber constitutes 0.1% to 3% by weight in the positive electrode active layer, for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, or any range of the above values. In some specific embodiments, the toughening fiber constitutes 1% to 2% by weight in the positive electrode active layer. Therefore, using toughening fibers at this content can improve the electrochemical performance of the positive electrode sheet and is beneficial for simultaneously improving mechanical properties.

[0136] In some embodiments, the thickness of the positive electrode active layer 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. In some specific embodiments, the thickness of the positive electrode active layer can be 80 μm to 120 μm. Therefore, the positive electrode active layer has a suitable thickness, which can improve the electrochemical performance of the battery while saving internal space.

[0137] In some implementations, the solid-state battery is an all-solid-state battery. This further enhances the safety performance of solid-state batteries.

[0138] 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".

[0139] 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.

[0140] 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.

[0141] 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".

[0142] Non-limitingly, a solid-state battery cell (which can be an all-solid-state battery cell) may include a positive electrode, a solid electrolyte sheet, and a negative electrode, with the solid electrolyte sheet 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 sheet acts as a conductor of ions between the positive and negative electrodes and also isolates them, thus preventing short circuits between the positive and negative electrodes.

[0143] In some implementations, a solid-state battery cell includes a solid-state battery cell.

[0144] In some implementations, the solid-state cell can be an all-solid-state cell.

[0145] In some embodiments, a solid-state battery cell (which may be an all-solid-state battery cell) includes a positive electrode, a solid electrolyte sheet, and a negative electrode stacked sequentially, wherein the positive electrode is the aforementioned positive electrode.

[0146] The following is a description of the negative electrode plate.

[0147] The negative electrode can be formed based on an etched solid electrolyte sheet 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.

[0148] 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.

[0149] In this application, the negative electrode sheet includes at least a negative electrode active layer.

[0150] In this application, the negative electrode active layer includes at least a negative electrode active material.

[0151] Without limitation, the negative electrode active layer may include a solid electrolyte. The solid electrolyte in the negative electrode active material layer may be referred to as "negative electrode electrolyte particles".

[0152] In this application, "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.

[0153] Without limitation, the weight percentage of the negative electrode active material in the negative electrode active layer can be ≥80%, and more particularly ≥90%.

[0154] Non-limitingly, the weight percentage of negative electrode electrolyte particles in the negative electrode active layer can be 0% to 30%, preferably 0.1% to 30%, and further preferably 5% to 20%.

[0155] In some implementations, the negative electrode active material is a lithium indium alloy (InLi alloy).

[0156] In some implementations, the negative electrode is an InLi alloy film.

[0157] 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.

[0158] In some embodiments, the negative electrode sheet may include a negative current collector and a negative active layer disposed on at least one surface of the negative current collector, the negative active layer comprising a negative 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 active layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0159] 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).

[0160] 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%.

[0161] 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%.

[0162] 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%.

[0163] 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 / cm can be selected. 3 ~1.8g / cm 3 .

[0164] 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, the compacted density of the negative electrode refers to the ratio of the mass of the negative electrode active layer to its volume, and the compacted density of the positive electrode refers to the ratio of the mass of the positive electrode active layer to its volume.

[0165] The following is a description of solid electrolyte sheets.

[0166] In this application, the solid electrolyte sheet can be introduced by forming electrode plates on both sides of the solid electrolyte sheet, or it can be introduced on the electrode plates. Understandably, the electrode plates can be positive or negative electrode plates.

[0167] Solid electrolyte sheets act as a conductor of ions between the positive and negative electrodes, and can also isolate the positive and negative electrodes to prevent short circuits between them.

[0168] Understandably, a solid electrolyte sheet includes a solid electrolyte. The solid electrolyte in the solid electrolyte sheet may be a solid electrolyte known in the art that can be used in solid-state batteries.

[0169] 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 sheet can be the same or different.

[0170] 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.

[0171] 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.

[0172] Solid electrolyte sheets can be prepared using dry methods. In some embodiments, solid electrolyte sheets can be formed by pressing solid electrolyte materials into solid electrolyte sheets. In other embodiments, solid electrolyte sheets are formed by pressing the constituent raw materials of the solid electrolyte sheet onto an electrode sheet. In still other embodiments, solid electrolyte sheets can also be prepared using methods such as fibrosis combined with calendering film formation, melt extrusion, and spraying.

[0173] Solid electrolyte sheets can also be prepared by a wet process, 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.

[0174] In some embodiments, the thickness of the solid electrolyte sheet 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.

[0175] In a non-limiting manner, the positive electrode, the solid electrolyte sheet, and the negative electrode can be assembled in a stacked manner, with the solid electrolyte sheet placed between the positive electrode and the negative electrode.

[0176] Non-limitingly, a solid-state battery cell can be prepared by stacking a positive electrode, a solid electrolyte sheet, and a negative electrode in sequence, placing the solid electrolyte sheet between the positive and negative electrode sheets, and then rolling them together.

[0177] Non-limitingly, a solid-state battery cell can be prepared by sequentially stacking a positive electrode, a solid electrolyte sheet, and a negative electrode, with the solid electrolyte sheet placed between the positive and negative electrodes, 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.

[0178] 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.

[0179] 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.

[0180] 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 1 This is an example of a square-structured solid-state battery cell 5.

[0181] In some implementations, refer to Figure 2 The outer packaging of the solid-state battery cell 5 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. The solid-state cell 52 is encapsulated within the receiving cavity. The number of solid-state cells 52 contained in the solid-state battery cell 5 can be one or more, which can be selected by those skilled in the art according to actual needs.

[0182] Solid-state batteries can be battery devices or battery packs.

[0183] 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.

[0184] Figure 3 This is battery device 4, used as an example. (See reference...) Figure 3 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 manner. Furthermore, the multiple solid-state battery cells 5 can be fixed in place using fasteners.

[0185] 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.

[0186] 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.

[0187] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5The battery pack 1 may include a battery box and multiple battery devices 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 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 box.

[0188] Secondly, this application also provides a method for preparing a solid-state battery, which includes the following steps:

[0189] S11: A positive electrode sheet is prepared by forming an undercoat layer on at least one surface of the positive current collector using a polymer and a conductive agent;

[0190] S12: Assemble the positive electrode to obtain a solid-state battery;

[0191] The weight ratio of polymer to conductive agent is (60-80):(20-40);

[0192] The polymer has a chemical formula with repeating unit A and repeating unit B, where repeating unit A includes a polar polymer block, and the side groups of repeating unit B have a structure as shown in general formula (I):

[0193]

[0194] Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 groups substituted with at least one C6-C8 aryl group.

[0195] In the solid-state battery preparation method provided in this application, a polymer is used to prepare the bottom coating layer in the positive electrode sheet. The polymer has a repeating unit A and a repeating unit B. The side groups of the repeating unit B are non-polar functional groups with large steric hindrance, such as C3-C6 branched alkyl groups, which can protect the polar functional groups such as ester groups in the polymer, play a role in regulating polarity, and promote the dissolution of the polymer in low-polarity solvents. Therefore, low-polarity solvents can be used to replace high-polarity solvents in the preparation process of the bottom coating layer, thereby minimizing the residual amount of high-polarity solvents in the bottom coating layer, and thus reducing the probability of side reactions between the sulfide electrolyte and other components in the positive electrode sheet and the high-polarity solvent. This effectively improves the electrochemical performance of the positive electrode sheet and increases the first-efficiency and capacity of the solid-state battery. Meanwhile, the repeating unit A includes a polar polymer block, which makes the polymer exhibit excellent adhesion. The polymer and the conductivity are synergistically combined at a mass ratio of (60-80):(20-40), so that the undercoat has both high adhesion and high conductivity. This is beneficial to increase the peel strength of the positive electrode sheet, reduce the internal resistance of the positive electrode sheet, and thus improve the cycle stability of the solid-state battery.

[0196] In some embodiments, R includes tert-butyl (-C(CH3)3), tert-pentyl (-C(CH3)2CH2CH3), isopropyl (-CH(CH3)2), triphenylmethyl and adamantyl At least one of them. Therefore, the large steric hindrance of the R group can effectively protect polar functional groups such as ester groups, thereby promoting the dissolution of the polymer in low polar solvents.

[0197] In some embodiments, R includes a tert-butyl group. Thus, the R group has high steric hindrance, a simple structure, and is easy to remove, exposing polar functional groups with high adhesive strength, thereby improving the peeling force of the positive electrode sheet.

[0198] In some embodiments, repeating unit A includes at least one selected from polyacrylic acid block, polytetrafluoroethylene block, polyvinylidene fluoride block, and polyurethane block. It is understood that repeating unit A may be selected from one of the aforementioned polymer blocks, or from a combination of at least two of the aforementioned polymer blocks. In some specific embodiments, repeating unit A may be a polyacrylic acid block. In other specific embodiments, repeating unit A may be a combination of polyacrylic acid block and polytetrafluoroethylene block. Thus, repeating unit A contains highly adhesive polar functional groups, which can improve the peel strength of the positive electrode, improve the internal resistance of the positive electrode, and thereby enhance the cycle stability of the solid-state battery.

[0199] In some embodiments, the positive electrode includes a positive current collector and a primer layer disposed on at least one surface of the positive current collector, and the method for preparing the primer layer includes the following steps:

[0200] S21: Dissolve the precursor in the first solvent, add a conductive agent, and obtain the primer adhesive;

[0201] S22: Apply the primer to at least one surface of the positive electrode current collector to obtain a liquid film;

[0202] S23: The precursor in the liquid film is pyrolyzed by heat treatment to form a polymer, thus obtaining the primer layer;

[0203] The precursor includes at least one of polytert-butyl acrylate and polytetrafluoroethylene-polytert-butyl acrylate block copolymer; the first solvent satisfies at least one of the following conditions: (1) dielectric constant ≤ 3, (2) dipole moment ≤ 7 × 10⁻⁶. -30 C·m,(3)Polarization index≤1.

[0204] Therefore, the precursor has tert-butyl acrylate functional groups as side groups. The tert-butyl group in these side groups, being a sterically hindered nonpolar functional group, can protect the polar functional groups in the precursor, regulate the precursor's polarity, and promote its dissolution in a low-polarity first solvent. Through coating and pyrolysis, some of the nonpolar functional groups in the precursor can be removed, exposing highly adhesive polar functional groups, while some nonpolar functional groups are retained, forming a polymer with repeating units A and B. Using this method to prepare the primer layer can, on the one hand, reduce the use and residue of highly polar solvents, effectively reducing the probability of side reactions between highly polar solvents and sulfide electrolytes, thereby improving the electrochemical performance of the positive electrode. On the other hand, it can improve the adhesion of the primer layer, giving the positive electrode higher peel strength, thus improving the internal resistance of the positive electrode.

[0205] In some embodiments, the precursor may include poly(tert-butylacrylate), PtBA. Poly(tert-butylacrylate) is a polymeric material polymerized from tert-butylacrylate (tBA) monomers, having a structure as shown in general formula (III):

[0206]

[0207] Where 'a' is selected from positive integers and represents the degree of polymerization of polytert-butyl acrylate. Its value can be 1, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200 or 500, or a range of any of the above values.

[0208] In some embodiments, polytert-butyl acrylate can undergo the following reaction during pyrolysis:

[0209]

[0210] Where a, m, and n are all selected from positive integers, representing the degree of polymerization of the polymer or polymer block. As shown in the above reaction formula, the tert-butyl groups on some of the side groups of polytert-butyl acrylate are removed by thermal desorption to form polyacrylic acid blocks, i.e., one of the repeating units A mentioned above; the tert-butyl groups on some of the side groups of polytert-butyl acrylate are retained to form polytert-butyl acrylate blocks, i.e., one of the repeating units B mentioned above, and finally a polymer with repeating units A and B is obtained.

[0211] Understandably, the pyrolysis reaction of the polytetrafluoroethylene-polytert-butyl acrylate block copolymer during heat treatment is similar to that of polytert-butyl acrylate. This block copolymer has polytetrafluoroethylene blocks and polytert-butyl acrylate blocks. Some of the tert-butyl groups on the side groups of the polytert-butyl acrylate blocks can be removed by pyrolysis, while others remain. In the final polymer, repeating unit A in its chemical formula includes both polytetrafluoroethylene and polyacrylate blocks, and repeating unit B includes a polytert-butyl acrylate block. In other embodiments, the precursor may also include block copolymers such as polyvinylidene fluoride-polytert-butyl acrylate block copolymers, polyurethane-polytert-butyl acrylate block copolymers, and polytetrafluoroethylene-polyvinylidene fluoride-polytert-butyl acrylate block copolymers.

[0212] In some embodiments, the weight percentage of the first solvent in the primer adhesive is 85% to 98%, for example, it can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or 98%, or any range of the above values. This allows the precursor to be fully dissolved in the first solvent, which is beneficial for improving the uniformity of the distribution of the pyrolysis-formed polymer in the primer adhesive layer, thereby enhancing the peel strength and electrochemical performance of the positive electrode.

[0213] In some embodiments, the conductive agent in the primer 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 in the primer may include at least one selected from SP, KS-6, acetylene black, vapor-grown carbon fibers (VGCF), carbon nanotubes (CNTs), and graphene. In some specific embodiments, the conductive agent in the primer may include at least one selected from conductive carbon black SP and carbon nanotubes (CNTs). This allows for the formation of continuous electron transport channels in the primer layer, reducing the internal resistance of the positive electrode.

[0214] In some embodiments, the weight ratio of the precursor to the conductive agent in the primer is (60-80):(20-40), for example, 60:40, 65:35, 65:35, 70:30, 75:25, or 80:20, or any range of the above values. In some specific embodiments, the weight ratio of the precursor to the conductive agent in the primer is (60-65):(35-40). Therefore, the primer layer exhibits excellent adhesive strength while maintaining good conductivity, thereby improving the peel strength and electrochemical performance of the positive electrode.

[0215] In some embodiments, the heat treatment satisfies the following conditions: a heating temperature of 80°C to 200°C and a heating time of 12 h to 24 h. As a non-limiting example, the heating temperature can be 80°C, 90°C, 100°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 for the thermal decomposition and release of some non-polar functional groups in the precursor, forming a polymer with high adhesion.

[0216] In some embodiments, the heat treatment meets the following conditions: the heating temperature is 150°C to 200°C, and the heating time is 15h to 20h. Therefore, the higher heating temperature can increase the pyrolysis rate of non-polar functional groups, resulting in a higher proportion of repeating unit A formed by pyrolysis, thereby improving the polymer's adhesive strength and the peel strength of the positive electrode sheet.

[0217] In some embodiments, the heat treatment can be carried out in a vacuum environment to promote the evaporation of the first solvent and the removal of nonpolar functional groups.

[0218] In some embodiments, the positive electrode sheet can be prepared by: dry mixing the components used to prepare the positive electrode active layer, such as positive electrode active particles, positive electrode electrolyte particles, positive electrode conductive agent, positive electrode binder, and any other components; then heating and pressurizing the mixed material to knead it into a clump; and hot rolling to form a self-supporting positive electrode active layer; forming a primer layer on at least one surface of the positive electrode current collector; and bonding the positive electrode active layer and the primer layer at high temperature to obtain the positive electrode sheet. Non-limitingly, a dual planetary mixer can be used for dry mixing. Non-limitingly, a kneading and heating process can be used. Non-limitingly, the temperature for hot rolling can be 75°C to 85°C, further such as 78°C, 80°C, 82°C, etc. Non-limitingly, the temperature for high-temperature bonding can be 75°C to 85°C, further such as 78°C, 80°C, 82°C, etc. Therefore, the method for assembling solid-state batteries using the positive electrode sheet is suitable for industrial mass production.

[0219] In other embodiments, the positive electrode sheet can be prepared by dispersing the components used to prepare the positive electrode active layer, such as positive electrode active particles, positive electrode electrolyte particles, positive electrode conductive agent, precursor, and any other components, in a first solvent to form a positive electrode slurry. Further, the positive electrode slurry is coated onto at least one surface of the positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained. Cold pressing can be performed using a cold rolling mill. Non-limitingly, the first solvent in the positive electrode slurry may include one or more of p-xylene, trimethylbenzene, butyl butyrate, heptane, etc., and more particularly, p-xylene. The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface of the positive electrode current collector or both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40% to 80%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 mPa·s to 25000 mPa·s. When coating the positive electrode slurry, the coating density per unit area, measured by dry weight (excluding solvent), can be 15 mg / cm³, based on the amount coated on one side of the positive electrode current collector. 2 ~35mg / cm 2 However, this is not the only possibility. The compaction density of the positive electrode sheet can be 3.0 g / cm³. 3 ~3.6g / cm 3 3.3g / cm³ is an option. 3 ~3.5g / cm 3 .

[0220] Thirdly, this application also provides a positive electrode sheet. The positive electrode sheet includes a positive current collector and a base coat layer disposed on at least one surface of the positive current collector; the base coat layer includes a polymer and a conductive agent in a weight ratio of (60-80):(20-40), the polymer having a chemical formula having repeating unit A and repeating unit B, repeating unit A including polar polymer blocks, and the side groups of repeating unit B having a structure as shown in general formula (I):

[0221]

[0222] Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 groups substituted with at least one C6-C8 aryl group.

[0223] In the positive electrode sheet provided in this application, the undercoat includes a polymer with repeating unit A and repeating unit B. The side groups of repeating unit B are non-polar functional groups with high steric hindrance, such as C3-C6 branched alkyl groups. These can protect the polar functional groups such as ester groups in the polymer, thereby regulating polarity and promoting the dissolution of the polymer in low-polarity solvents. Therefore, low-polarity solvents can be used to replace high-polarity solvents during the preparation of the undercoat, minimizing the residual amount of high-polarity solvents in the undercoat and reducing the probability of side reactions between the sulfide electrolyte and other components in the positive electrode sheet and the high-polarity solvent. This effectively improves the electrochemical performance of the positive electrode sheet. Meanwhile, repeating unit A includes polar polymer blocks, giving the polymer excellent adhesion. The polymer and conductivity are synergistically combined at a mass ratio of (60-80):(20-40), resulting in a base coat that possesses both high adhesion and high conductivity. This is beneficial for increasing the peel strength of the positive electrode and reducing its internal resistance. Using the positive electrode provided in this application in solid-state batteries can effectively improve the initial efficiency and capacity of solid-state batteries, while also improving their cycle performance.

[0224] In some embodiments, the positive electrode is the same as the positive electrode in the aforementioned solid-state battery. This effectively improves the peel strength and electrochemical performance of the positive electrode.

[0225] 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.

[0226] In some embodiments, the electrical device includes at least one of the solid-state batteries of any of the embodiments provided in this application.

[0227] 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.

[0228] As an electrical device, solid-state batteries can be selected based on its usage requirements.

[0229] Figure 6Here is 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.

[0230] 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.

[0231] 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.

[0232] Example 1

[0233] 1) Preparation of the positive electrode sheet:

[0234] Take the positive electrode active material NCM 811 The electrolyte consists of sulfide electrolyte LPSCl, positive electrode conductive agent VGCF, positive electrode binder PTFE, and cellulose fibers (diameter 20μm, length 150μm, aspect ratio 7.5, tensile strength 600MPa, tensile modulus 15GPa, specific surface area 250m²). 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 film, resulting in a positive electrode active layer with a thickness of 100μm.

[0235] Polytert-butyl acrylate was dissolved in xylene, and conductive agent SP was added. The mixture was then homogenized using a high-speed mixing method to obtain a primer. The primer had a solid content of 7% (i.e., xylene was 93% by weight), and the weight ratio of polytert-butyl acrylate to conductive agent SP was 60:40. The primer was uniformly coated onto an aluminum foil current collector to form a liquid film. The liquid film was then heated at 160°C for 15 hours and subjected to vacuum treatment to remove xylene. Simultaneously, some of the tert-butyl groups in the polytert-butyl acrylate were pyrolyzed to release isobutylene, which then formed a polymer, resulting in a primer layer with a thickness of 2 μm.

[0236] The positive electrode active layer was dried in a vacuum oven at 80°C for 12 hours, and the positive electrode active layer and the primer coating layer on the aluminum plate current collector were bonded at 80°C. Then, the positive electrode sheet was obtained by die cutting with a die size of 6cm×9.5cm.

[0237] 2) Preparation of solid electrolyte sheets:

[0238] 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.

[0239] 3) Preparation of the negative electrode sheet:

[0240] Nano-silicon, graphite, VGCF, and PVDF (anode active material), in a weight ratio of 62:35:1:2, were used as the negative electrode active material. The PVDF binder was dissolved in NMP, and then the negative electrode active material and the negative electrode conductive material were added and stirred to form a homogenized slurry with a solid content of 30%. The negative electrode 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 a thickness of 30 μm was achieved. Finally, the foil was die-cut using a die with dimensions of 6.4 cm × 9.7 cm to obtain the negative electrode sheet.

[0241] 4) Fabrication of all-solid-state batteries:

[0242] The positive electrode, solid electrolyte sheet, and negative electrode are stacked in sequence and assembled in an alternating layering manner. After hot pressing at 80°C and encapsulated under negative pressure with aluminum-plastic film, a soft-pack all-solid-state battery is obtained.

[0243] As shown in Table 1 below, the pouch-pack all-solid-state batteries of Examples 2-16 and Comparative Examples 1-3 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:

[0244] Example 2: The solid content of the primer is 2% (i.e., the weight percentage of xylene is 98%).

[0245] Example 3: The solid content of the primer is 15% (i.e., xylene by weight is 85%).

[0246] Example 4: In the primer adhesive, the weight ratio of polytert-butyl acrylate to conductive agent SP is 80:20.

[0247] Example 5: In the primer adhesive, the weight ratio of polytert-butyl acrylate to conductive agent SP is 70:30.

[0248] Example 6: In the primer adhesive, the weight ratio of polytert-butyl acrylate and conductive agent SP is 50:50.

[0249] Example 7: In the primer adhesive, the weight ratio of polytert-butyl acrylate to conductive agent SP is 20:80.

[0250] Example 8: The thickness of the primer layer is 0.5 μm.

[0251] Example 9: The thickness of the primer layer is 10 μm.

[0252] Example 10: The liquid film was heated at a temperature of 80°C.

[0253] Example 11: The temperature at which the liquid film is heated is 200°C.

[0254] Example 12: The liquid film was heated at high temperature for 12 hours.

[0255] Example 13: The liquid film was heated at high temperature for 24 hours.

[0256] Example 14: The conductive agent in the primer was replaced with carbon nanotubes (CNTs).

[0257] Example 15: The polytert-butyl acrylate in the primer was replaced with polytert-amyl acrylate.

[0258] Example 16: The polytert-butyl acrylate in the primer was replaced with polytetrafluoroethylene-polytert-butyl acrylate.

[0259] Comparative Example 1: No base coating layer is provided in the positive electrode sheet, and the positive active layer is provided on the surface of the aluminum foil current collector;

[0260] Comparative Example 2: The primer layer was prepared by the following method: polyvinylidene fluoride (PVDF) and conductive agent SP were dispersed in N-methylpyrrolidone (NMP) at a weight ratio of 60:40 to obtain a primer solution with a solid content of 7%; the primer solution was uniformly coated on an aluminum foil current collector to form a liquid film; the liquid film was heated at 160°C for 15 hours and then vacuum-treated to remove NMP, resulting in a primer layer with a thickness of 2 μm.

[0261] Comparative Example 3: The primer layer was prepared by the following method: polymethyl acrylate and conductive agent SP were dispersed in deionized water at a weight ratio of 60:40 to obtain a primer solution with a solid content of 7%; the primer solution was uniformly coated on the aluminum foil current collector to form a liquid film; the liquid film was heated at 100°C for 15 hours and vacuum treated to remove the deionized water, resulting in a primer layer with a thickness of 2 μm.

[0262] Table 1. Relevant parameters of the primer coating

[0263]

[0264] Note: In Table 1, the weight ratio refers to the weight ratio of the precursor to the conductive agent.

[0265] Test case

[0266] The following tests were conducted on the positive electrode sheets of Examples 1-16, Comparative Examples 1-3, and the pouch-type all-solid-state battery:

[0267] (1) Polymer Structure Identification: The polymer structure was identified using infrared spectroscopy. The polymer sample was dissolved in chloroform. The sample solution was placed in the infrared spectrometer, and the instrument parameters were adjusted and a reference calibration was performed to ensure that the instrument was in optimal working condition. Infrared spectroscopy was performed using either transmission or reflection mode. The infrared spectrum was recorded, including the position and intensity of the absorption peaks. The structure was identified by comparing the infrared spectrum of the sample with that of known polymers.

[0268] (2) Number-average molecular weight of polymer: The molecular weight of polymer is determined by X-ray scattering. First, the polymer solution is added to the X-ray scattering instrument. Then, X-rays are irradiated into the polymer solution and the scattering intensity is recorded. Finally, the molecular weight of polymer is calculated based on the relationship between the molecular weight of polymer and the scattering intensity.

[0269] (3) Molar ratio of repeating unit A and repeating unit B in polymer: The molar ratio of different structural units of polymer is also analyzed by infrared spectroscopy. By testing the sample under different infrared spectra, the structural units in its structure are determined. Based on the infrared spectroscopy test results, the arrangement of polymer chains in the sample is inferred, and the molar ratio of different repeating units is calculated.

[0270] (4) Residual amount of solvent: Gas chromatography is used to confirm the residual amount of solvent. The solvent in the sample is evaporated into gas and then analyzed by gas chromatography. The residual amount is determined by the residence time of the solvent in the chromatographic column and the area of ​​the characteristic peak.

[0271] (5) Peel strength of the positive electrode: Take a flat, thin steel plate, approximately 200mm-300mm in length and 40mm-60mm in width. Apply a strip of double-sided tape to the center of the steel plate, ensuring the tape is longer than the sample test length and the same width as the positive electrode. Smooth the tape firmly to ensure it adheres tightly to the center of the steel plate. Peel off the covering paper of the double-sided tape and attach the positive electrode to the tape, ensuring a perfect fit. Insert the steel plate with the attached positive electrode into the lower clamp of the tensile testing machine and fix it vertically. Insert the unattached positive electrode into the upper clamp, fixing it at a 180° (or 90°) angle to the positive electrode fixed in the upper clamp. Apply a load to the positive electrode at a stable speed of 5mm / min using the tensile testing machine and record the peel strength of the sample.

[0272] (6) Electrical performance of soft-pack all-solid-state battery: The charging cut-off voltage is 4.3V, the discharging cut-off voltage is 2V, the first efficiency, discharge specific capacity and 50-cycle capacity retention rate of the all-solid-state battery are tested at a current of 0.1C, and the test pressure is 50MPa.

[0273] The performance test results of Examples 1-16 and Comparative Examples 1-3 are shown in Tables 2 and 3 below. Figure 7 As shown.

[0274] Table 2. Performance test results of the primer coating

[0275]

[0276] Note: In Table 2, the first solvent refers to xylene, and the second solvent refers to NMP or water.

[0277] Table 3. Performance test results of positive electrode and battery

[0278]

[0279] Depend on Figure 7 Infrared spectroscopy reveals that the polymer of Example 1 has a structure as shown in general formula (Ⅳ):

[0280]

[0281] According to the test results in Tables 2 and 3, Example 1 uses polytert-butyl acrylate as a precursor, and the resulting primer layer contains a polymer with a structure as shown in general formula (Ⅳ). The number average molecular weight of the polymer is about 150,000, and the molar ratio of repeating unit A to sufficient unit B of the polymer is about 2:1. It has strong adhesion, which is beneficial to improving the peel strength of the positive electrode sheet.

[0282] The difference between Examples 1 to 3 lies in the solid content (or the content of the first solvent) of the primer. As the solid content of the primer increases (or as the content of the first solvent decreases), the residual amount of the first solvent in the resulting primer layer gradually decreases. The peel strength of the positive electrode first increases and then decreases. The first efficiency, 0.1C discharge specific capacity, and 50-cycle capacity retention rate at 0.1C of the soft-pack all-solid-state battery also first increase and then decrease.

[0283] The difference between Examples 1 and Examples 4-7 lies in the weight ratio of the precursor (or the polymer obtained from pyrolysis) to the conductive agent. As the content of the precursor (or polymer) increases, the residual amount of the first solvent in the resulting undercoat layer remains essentially constant, the peel strength of the positive electrode gradually increases, while the initial efficiency, 0.1C discharge specific capacity, and capacity retention rate after 50 cycles at 0.1C of the pouch-pack all-solid-state battery all show a trend of first increasing and then decreasing. Therefore, when the weight ratio of the precursor to the conductive agent in Example 1 is 60:40, the electrochemical performance of the pouch-pack all-solid-state battery is particularly outstanding.

[0284] The difference between Examples 1 and Examples 8-9 lies in the thickness of the undercoat layer. As the thickness of the undercoat layer increases, the residual amount of the first solvent in the resulting undercoat layer gradually increases, leading to a gradual increase in the peel strength of the positive electrode sheet. However, the initial efficiency, 0.1C discharge specific capacity, and capacity retention rate after 50 cycles at 0.1C of the pouch-pack all-solid-state battery gradually decrease. Therefore, when the thickness of the undercoat layer in Example 8 is 0.5 μm, the electrochemical performance of the pouch-pack all-solid-state battery is more significant, but the peel strength of the positive electrode sheet is not as good as in Example 1.

[0285] The difference between Example 1 and Examples 10-11 lies in the heating temperature during the preparation of the base coating adhesive layer. As the heating temperature increases, the molar amount of repeating unit A in the polymer gradually increases, the adhesive force of the polymer gradually increases, and the peel strength of the positive electrode sheet and the electrochemical performance of the soft-pack all-solid-state battery also increase accordingly.

[0286] The difference between Example 1 and Examples 12-13 lies in the heating time during the preparation of the base coating adhesive layer. As the heating time increases, the molar amount of repeating unit A in the polymer gradually increases, the adhesive force of the polymer gradually increases, and the peel strength of the positive electrode sheet and the electrochemical performance of the soft-pack all-solid-state battery also increase accordingly.

[0287] The difference between Example 1 and Example 14 lies in the conductive agent. The conductive agent is replaced with CNT instead of SP, which slightly reduces the peel strength of the positive electrode and the electrochemical performance of the soft-pack all-solid-state battery.

[0288] The difference between Example 1 and Examples 15-16 lies in the precursor. Example 15 uses polytert-amyl acrylate as the precursor, while Example 16 uses polytetrafluoroethylene-polytert-butyl acrylate as the precursor. The number-average molecular weight of the polymer in the resulting undercoat layer increases, and the molar amount of repeating unit A decreases, which reduces the adhesion of the polymer. As a result, the peel strength of the positive electrode and the electrochemical performance of the soft-pack all-solid-state battery show a significant decrease compared to Example 1.

[0289] Meanwhile, in Examples 1-16, the residual amount of the first solvent (xylene) in the primer layer was 0.011% to 0.050%, while the residual amount of the second solvent was less than 0.01%. This is because it is difficult to prevent moisture intrusion from the air during the preparation of the primer layer. In Comparative Example 2, which used a PVDF and NMP formulation, the residual amount of the second solvent (NMP) in the primer layer increased to 0.05%; in Comparative Example 3, which used a polymethyl acrylate and water formulation, the residual amount of the second solvent (water) in the primer layer increased to 0.03%. This demonstrates that Examples 1-16 of this application can effectively reduce the residual amount of the second solvent in the primer layer, thereby reducing the impact on the sulfide electrolyte in the positive electrode.

[0290] According to the test results in Table 3, the first-cycle efficiency, 0.1C discharge specific capacity, and 50-cycle capacity retention at 0.1C of the pouch-type all-solid-state batteries in Examples 1-16 are all higher than those of the pouch-type all-solid-state batteries in Comparative Examples 1-3. This indicates that the present application uses a low-polarity solvent to dissolve the precursor in a low-polarity solvent to prepare the primer, and forms a primer layer containing a polymer (which is also soluble in low-polarity solvents) through coating and pyrolysis. The entire preparation process does not require the use of high-polarity solvents, thus minimizing the residual amount of high-polarity solvents in the primer layer, thereby effectively improving the first-cycle efficiency, capacity, and cycle performance of the solid-state battery. Meanwhile, the positive electrode sheets in Examples 1-16 exhibit high peel strength, which is beneficial for promoting the stable electrochemical performance of the solid-state battery.

[0291] 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.

[0292] 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, characterized in that, The device includes a positive electrode sheet, the positive electrode sheet comprising a positive current collector, and a base coat adhesive layer disposed on at least one surface of the positive current collector; the base coat adhesive layer comprises a polymer and a conductive agent in a weight ratio of (60-80):(20-40), the polymer having a chemical formula having repeating unit A and repeating unit B, the repeating unit A comprising a polar polymer block, and the side groups of the repeating unit B having a structure as shown in general formula (I): Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 alkyl groups substituted with at least one C6-C8 aryl group.

2. The solid-state battery according to claim 1, characterized in that, R includes at least one of tert-butyl, tert-amyl, isopropyl, triphenylmethyl, and adamantyl.

3. The solid-state battery according to claim 2, characterized in that, R includes tert-butyl.

4. The solid-state battery according to any one of claims 1 to 3, characterized in that, The repeating unit B has a structure as shown in general formula (II): Where n is selected from positive integers.

5. The solid-state battery according to any one of claims 1 to 4, characterized in that, The repeating unit A includes at least one of polyacrylic acid block, polytetrafluoroethylene block, polyvinylidene fluoride block, and polyurethane block.

6. The solid-state battery according to any one of claims 1 to 5, characterized in that, The molar ratio of repeating unit A to repeating unit B is (1-10):

1.

7. The solid-state battery according to any one of claims 1 to 6, characterized in that, The number average molecular weight of the polymer is 20,000 to 500,000.

8. The solid-state battery according to any one of claims 1 to 7, characterized in that, The weight ratio of the polymer to the conductive agent is (60-65):(35-40).

9. The solid-state battery according to any one of claims 1 to 8, characterized in that, The conductive agent includes at least one of conductive carbon black, conductive graphite, acetylene black, carbon nanotubes, graphene, and carbon fiber.

10. The solid-state battery according to any one of claims 1 to 9, characterized in that, The primer layer further includes a first solvent at a weight percentage of 0.01% to 0.1%, wherein the first solvent satisfies at least one of the following conditions: (1) dielectric constant ≤ 3, (2) dipole moment ≤ 7 × 10⁻⁶. -30 C·m,(3)Polarization index≤1.

11. The solid-state battery according to claim 10, characterized in that, The first solvent includes at least one of toluene, xylene, n-heptane, n-hexane, anisole, n-butyl ether, and butyl butyrate.

12. The solid-state battery according to any one of claims 1 to 11, characterized in that, The thickness of the base coating is 0.5μm to 10μm.

13. The solid-state battery according to any one of claims 1 to 12, characterized in that, The positive electrode sheet further includes a positive active layer, which is disposed on the surface of the bottom coating layer away from the positive current collector, and the positive active layer includes a sulfide electrolyte.

14. The solid-state battery according to any one of claims 1 to 13, characterized in that, The solid-state battery is an all-solid-state battery.

15. A method for preparing a solid-state battery, characterized in that, Includes the following steps: A positive electrode sheet is prepared by forming an undercoat layer on at least one surface of a positive current collector using a polymer and a conductive agent. The positive electrode sheet is assembled to obtain a solid-state battery; The weight ratio of the polymer to the conductive agent is (60-80):(20-40); The polymer has a chemical formula having repeating unit A and repeating unit B, wherein repeating unit A comprises a polar polymer block, and the side groups of repeating unit B have a structure as shown in general formula (I): Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 groups substituted with at least one C6-C8 aryl group.

16. The method for preparing a solid-state battery according to claim 15, characterized in that, R includes at least one of tert-butyl, tert-amyl, isopropyl, triphenylmethyl, and adamantyl.

17. The method for preparing a solid-state battery according to claim 15 or 16, characterized in that, The polymer block A includes at least one of polyacrylic acid block, polytetrafluoroethylene block, polyvinylidene fluoride block, and polyurethane block.

18. The method for preparing a solid-state battery according to any one of claims 15 to 17, characterized in that, The method for preparing the base coating layer includes the following steps: The precursor is dissolved in the first solvent, and the conductive agent is added to obtain the primer adhesive; The primer is applied to at least one surface of the positive electrode current collector to obtain a liquid film. The precursor in the liquid film is pyrolyzed by heat treatment to form the polymer, thereby obtaining the base coating layer; The precursor includes at least one of polytert-butyl acrylate and polytetrafluoroethylene-polytert-butyl acrylate block copolymer; the first solvent satisfies at least one of the following conditions: (1) dielectric constant ≤ 3, (2) dipole moment ≤ 7 × 10⁻⁶. -30 C·m,(3)Polarization index≤1.

19. The method for preparing a solid-state battery according to claim 18, characterized in that, The first solvent accounts for 85% to 98% by weight in the primer adhesive.

20. The method for preparing a solid-state battery according to claim 18 or 19, characterized in that, The primer adhesive meets 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 weight ratio of the precursor to the conductive agent is (60-80): (20-40).

21. The method for preparing a solid-state battery according to any one of claims 18 to 20, characterized in that, The heat treatment meets the following conditions: the heating temperature is 80℃~200℃, and the heating time is 12h~24h.

22. The method for preparing a solid-state battery according to claim 21, characterized in that, The heat treatment meets the following conditions: the heating temperature is 150℃~200℃, and the heating time is 15h~20h.

23. A positive electrode plate, characterized in that, The positive electrode includes a positive current collector and a base coat layer disposed on at least one surface of the positive current collector; the base coat layer includes a polymer and a conductive agent in a weight ratio of (60-80):(20-40), the polymer having a chemical formula having repeating unit A and repeating unit B, the repeating unit A including a polar polymer block, and the side groups of the repeating unit B having a structure as shown in general formula (I): Wherein, R includes C3-C6 branched alkyl groups, ... and C6-C6 branched alkyl groups. 10 cycloalkyl, C6-C 20 The aryl group and at least one of the C1-C3 groups substituted with at least one C6-C8 aryl group.

24. The positive electrode sheet according to claim 23, characterized in that, The positive electrode is the positive electrode in the solid-state battery according to any one of claims 2 to 14.

25. An electrical appliance, characterized in that, The solid-state battery includes at least one of the solid-state battery according to any one of claims 1 to 14, the solid-state battery prepared by the method of preparing the solid-state battery according to any one of claims 15 to 22, and the positive electrode sheet according to claim 23 or 24.

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