Solid-state battery and preparation method therefor, and electric device

Abstract

The application relates to a solid-state battery, a preparation method thereof and an electric device, the solid-state battery comprising a positive electrode layer, a negative electrode layer, a functional layer arranged on at least one surface of the negative electrode layer, and a solid electrolyte layer arranged between the functional layer and the positive electrode layer, wherein the functional layer comprises a porous graphene-based material, the porosity of the single-piece porous graphene-based material is 3% to 9%, and the average pore diameter of the porous graphene-based material is 0.2 nm to 15 nm; the mass content of the porous graphene-based material in the functional layer is 91% to 100% under the condition that the state of charge (SOC) of the solid-state battery is less than or equal to 10%, so that the cycle performance of the solid-state battery can be improved.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, and further to solid-state batteries, their preparation methods, and electrical devices. Background Technology

[0002] Solid-state batteries use a non-flammable solid electrolyte instead of the organic electrolyte in traditional liquid secondary batteries, significantly improving battery safety and are considered the next generation of batteries closest to industrialization. However, the cycle performance of solid-state batteries needs further improvement. Summary of the Invention

[0003] In view of the above problems, according to various embodiments and examples of this application, this application provides a solid-state battery, a method for preparing the same, and an electrical device thereof, which aims to improve the cycle performance of solid-state batteries.

[0004] A first aspect of this application provides a solid-state battery, comprising a positive electrode layer, a negative electrode layer, a functional layer disposed on at least one surface of the negative electrode layer, and a solid electrolyte layer disposed between the functional layer and the positive electrode layer. The functional layer comprises a porous graphene-like material, wherein the porosity of a single piece of the porous graphene-like material is 3% to 9%, and the average pore size of the porous graphene-like material is 0.2 nm to 15 nm. Under the condition that the solid-state battery is less than or equal to 10% SOC, the mass content of the porous graphene-like material in the functional layer is 91% to 100%.

[0005] In the aforementioned solid-state battery, a functional layer is placed between the negative electrode layer and the solid electrolyte layer. On the one hand, due to the high mechanical properties of porous graphene materials, controlling the porosity of a single porous graphene material within the aforementioned range, and controlling the mass content of porous graphene materials in the functional layer within the aforementioned range under the condition that the solid-state battery is less than or equal to 10% SOC, can effectively improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage. This effectively isolates the negative electrode layer and the solid electrolyte layer, reducing side reactions between them. On the other hand, controlling the average pore size of the porous graphene materials in the functional layer within the aforementioned range is beneficial for lithium ions to pass through the functional layer and reach the negative electrode layer. Furthermore, controlling the porosity of a single porous graphene material within the aforementioned range can promote rapid lithium ion transport, reduce the formation of lithium dendrites and / or lithium deposition between the solid electrolyte layer and the functional layer, thereby reducing side reactions between lithium dendrites and / or lithium deposition and the solid electrolyte layer, reducing lithium ion consumption, and thus effectively improving the cycle performance of the solid-state battery.

[0006] In some embodiments, the porosity of the monolayer porous graphene-like material is 3% to 7%. This can further improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage, thereby further improving the cycle performance of the solid-state battery.

[0007] In some embodiments, the porous graphene-like material in the functional layer has a mass content of 94% to 100%. This can further improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage, thereby further improving the cycle performance of the solid-state battery.

[0008] In some embodiments, the average sheet diameter of the porous graphene-like material is 5 μm to 100 μm. Controlling the average sheet diameter of the porous graphene-like material within this range is beneficial for further improving the strength of the functional layer, while also enabling faster lithium-ion transport within the functional layer, which is beneficial for improving the cycle stability of the solid-state battery.

[0009] In some embodiments, the average thickness of the porous graphene-like material is less than or equal to 20 nm. By controlling the average thickness of the porous graphene-like material within the above range, the porous graphene-like material in the functional layer is arranged more densely, which can reduce the risk of lithium dendrites forming at the pores between the porous graphene-like materials.

[0010] In some embodiments, the average sheet diameter of the porous graphene-like material is 20 μm to 100 μm. Controlling the average sheet diameter of the porous graphene-like material within this range is beneficial for further improving the strength of the functional layer, while also enabling faster lithium-ion transport within the functional layer, which is beneficial for improving the cycle stability of the solid-state battery.

[0011] In some embodiments, the average thickness of the porous graphene-like material is 0.7 nm to 5 nm. By controlling the average thickness of the porous graphene-like material within the above range, the porous graphene-like material in the functional layer is arranged more densely, which can reduce the risk of lithium dendrites forming at the pores between the porous graphene-like materials.

[0012] In some embodiments, the porous graphene-like material includes one or more of porous graphene, porous graphene oxide, and porous reduced graphene oxide.

[0013] In some embodiments, the porosity of the functional layer is 3% to 20%.

[0014] In some embodiments, the thickness of the functional layer is 100nm to 500nm. This reduces the lithium uptake of the functional layer while giving it higher strength, which is beneficial for further improving the cycle performance of the solid-state battery.

[0015] A second aspect of this application provides a method for preparing a solid-state battery, the solid-state battery comprising a positive electrode layer, a negative electrode layer, a functional layer disposed on at least one surface of the negative electrode layer, and a solid electrolyte layer disposed between the functional layer and the positive electrode layer, wherein the functional layer comprises a porous graphene-like material, the porosity of a single piece of the porous graphene-like material is 3% to 9%, and the average pore size of the porous graphene-like material is 0.2 nm to 15 nm; under the condition that the solid-state battery is less than or equal to 10% SOC, the mass content of the porous graphene-like material in the functional layer is 91% to 100%; the method for preparing the solid-state battery includes the step of preparing the porous graphene-like material:

[0016] The raw materials for graphene-like materials are oxidized to form a porous structure, thereby obtaining the porous graphene-like material.

[0017] In the solid-state battery prepared by the above method, a functional layer is set between the negative electrode layer and the solid electrolyte layer. On the one hand, due to the high mechanical properties of porous graphene materials, controlling the porosity of the porous graphene materials in a single piece within the above-mentioned range and controlling the mass content of porous graphene materials in the functional layer within the above-mentioned range under the condition that the solid-state battery is less than or equal to 10% SOC can effectively improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage. This effectively isolates the negative electrode layer and the solid electrolyte layer, reducing side reactions between them. On the other hand, controlling the average pore size of the porous graphene materials in the functional layer within the above-mentioned range is beneficial for lithium ions to pass through the functional layer and reach the negative electrode layer. Furthermore, controlling the porosity of the porous graphene materials in a single piece within the above-mentioned range can promote the rapid transport of lithium ions, thereby effectively improving the cycle performance of the solid-state battery.

[0018] In some embodiments, the oxidation treatment temperature is -20°C to 100°C.

[0019] In some embodiments, the oxidation treatment time is 1 min to 200 h.

[0020] In some embodiments, the oxidant used in the oxidation treatment includes one or more of hydrogen peroxide, nitric acid, ammonia, sulfuric acid, and potassium permanganate.

[0021] In some embodiments, the raw materials for the graphene-based materials include one or more of graphene, graphene oxide, and reduced graphene oxide.

[0022] In some embodiments, the oxidation treatment step is followed by a reduction treatment of the product obtained from the oxidation treatment.

[0023] In some implementations, the reduction treatment temperature is -20°C to 60°C.

[0024] In some implementations, the reduction process takes 1 minute to 200 hours.

[0025] In some embodiments, the reducing agent used in the reduction process includes one or more of hydrazine hydrate, dimethylhydrazine, hydroquinone, sodium borohydride, and liquid hydrazine.

[0026] By controlling at least one of the following: oxidation treatment temperature, oxidation treatment time, oxidant concentration, oxidant type, reduction treatment temperature, reduction treatment time, reducing agent concentration, and reducing agent type, the average pore size and porosity of a single porous graphene material can be controlled.

[0027] A third aspect of this application provides an electrical device comprising at least one of the solid-state battery described in the first aspect of this application and a solid-state battery prepared by the method described in the second aspect of this application.

[0028] The electrical device of this application includes at least one of the solid-state battery provided in this application and the solid-state battery prepared by the preparation method provided in this application, and thus has at least the same advantages as at least one of the solid-state battery and the solid-state battery prepared by the preparation method.

[0029] Details of one or more embodiments or examples of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description

[0030] To better describe and illustrate the implementation methods, 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 implementation methods, embodiments, or examples, or the best mode of these applications as currently understood.

[0031] In the attached diagram:

[0032] Figure 1 This is a schematic diagram of an electrode assembly according to one embodiment of this application.

[0033] Figure 2 This is a three-dimensional structural diagram of a solid-state battery according to an embodiment of this application.

[0034] Figure 3 for Figure 2 An exploded view of a solid-state battery according to an embodiment of this application is shown.

[0035] Figure 4 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.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Solid-state battery; 11. Casing; 12. Electrode assembly; 121. Positive electrode layer; 1211. Positive current collector; 1212. Positive active layer; 122. Solid electrolyte layer; 123. Negative electrode layer; 1231. Negative current collector; 1232. Negative active layer; 124. Functional layer; 13. Cover plate; 2. Electrical device. Detailed Implementation

[0038] Hereinafter, some embodiments of this application are described in detail with appropriate reference to the accompanying drawings. However, some unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0039] 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 the specific range. Ranges defined in this way can include or exclude endpoints. Any endpoint can be included or excluded independently, and they 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 a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0040] 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% is permissible. For instance, taking "about 20°C" as an example, where the approximation is ±1°C, approximate values ​​such as 19°C and 19.5°C within the approximation range indicated by "about 20°C" should also be included in the range indicated by "about 20°C".

[0041] 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.

[0042] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0043] 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.

[0044] 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.

[0045] 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."

[0046] 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.

[0047] 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."

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] In this application, the term "room temperature" generally refers to 4℃ ~ 35℃, and may refer to 20℃ ± 5℃. In some embodiments or examples of this application, room temperature refers to 20℃ ~ 30℃.

[0055] 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, 3~5 h or 3-5 h 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.

[0056] 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.

[0057] During the charging and discharging process of solid-state batteries, active ions such as lithium ions continuously deposit in the negative electrode layer to form lithium dendrites, which leads to side reactions when the negative electrode layer comes into contact with the solid electrolyte layer, affecting the cycle performance of the solid-state battery.

[0058] Based on this, in a first aspect, a solid-state battery is provided, comprising a positive electrode layer, a negative electrode layer, a functional layer disposed on at least one surface of the negative electrode layer, and a solid electrolyte layer disposed between the functional layer and the positive electrode layer. The functional layer comprises a porous graphene-like material, wherein the porosity of a single piece of the porous graphene-like material is 3% to 9%, and the average pore size of the porous graphene-like material is 0.2 nm to 15 nm. Under the condition that the solid-state battery is less than or equal to 10% SOC, the mass content of the porous graphene-like material in the functional layer is 91% to 100%.

[0059] In the aforementioned solid-state battery, a functional layer is placed between the negative electrode layer and the solid electrolyte layer. On the one hand, due to the high mechanical properties of porous graphene materials, controlling the porosity of a single porous graphene material within the aforementioned range, and controlling the mass content of porous graphene materials in the functional layer within the aforementioned range under the condition that the solid-state battery is less than or equal to 10% SOC, can effectively improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage. This effectively isolates the negative electrode layer and the solid electrolyte layer, reducing side reactions between them. On the other hand, controlling the average pore size of the porous graphene materials in the functional layer within the aforementioned range is beneficial for lithium ions to pass through the functional layer and reach the negative electrode layer. Furthermore, controlling the porosity of a single porous graphene material within the aforementioned range can promote rapid lithium ion transport, reduce the formation of lithium dendrites and / or lithium deposition between the solid electrolyte layer and the functional layer, thereby reducing side reactions between lithium dendrites and / or lithium deposition and the solid electrolyte layer, reducing lithium ion consumption, and thus effectively improving the cycle performance of the solid-state battery.

[0060] It should be noted that during solid-state battery charging, lithium may deposit in the functional layer; during solid-state battery discharging, some or all of the deposited lithium may return to the positive electrode layer. Therefore, the mass content of porous graphene-like materials in the functional layer will vary with different SOC conditions.

[0061] As a non-limiting example, the porosity of a monolithic porous graphene-like material includes, but is not limited to, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, or any two of the foregoing; the average pore size of the porous graphene-like material includes, but is not limited to, 0.2nm, 0.25nm, 0.3nm, 0.35nm, 0.4nm, 0.45nm, 0.5nm, 0.55nm, 0.6nm, 0.65nm, 0.7nm, 0.75nm, 0.8nm, 0.85nm, 0.9nm, 1nm, 3nm, 5nm, 7nm, 9nm, 10nm, 12nm, 15nm, or any two of the foregoing; in solid-state batteries, the porosity is less than or equal to 10%. Under SOC conditions, the mass content of porous graphene-like materials in the functional layer includes, but is not limited to: 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, and 100%.

[0062] In the aforementioned solid-state batteries, when the porosity of a single porous graphene-like material is too high, the strength of the functional layer is low. During the charge-discharge cycle of the solid-state battery, lithium dendrites near the negative electrode side may pierce the functional layer, or the functional layer may break, leading to side reactions between the negative electrode layer and the solid electrolyte layer, thus deteriorating the cycle performance of the solid-state battery. Conversely, if the porosity of a single porous graphene-like material is too low, it may affect lithium-ion transport, resulting in poor cycle performance. If the average pore size of the porous graphene-like material is too small, lithium ions have difficulty passing through the functional layer, forming lithium dendrites between the functional layer and the solid electrolyte layer. If the average pore size of the porous graphene-like material is too large, lithium ions are prone to depositing lithium metal at the pore locations of the porous graphene-like material. The lithium dendrites or lithium deposits formed between the solid electrolyte layer and the functional layer can further react with the solid electrolyte layer to form an SEI film, continuously consuming lithium ions and thus deteriorating the cycle performance of the solid-state battery. When the mass content of porous graphene-like materials in the functional layer is too low, the strength of the functional layer is insufficient. During charge-discharge cycles, lithium dendrites formed on one side of the negative electrode layer may pierce the functional layer, and the functional layer may break, thus affecting the cycle performance of the solid-state battery.

[0063] Non-limitingly, by disassembling a solid-state battery, confirming the relative positions of the positive electrode layer, negative electrode layer, functional layer, and solid electrolyte layer, peeling off the functional layer, then ultrasonically dispersing the functional layer in ethanol, separating a single piece of porous graphene material, using TEM to observe multiple pieces of porous graphene material (>50 pieces), obtaining the sum of the pore areas of multiple pieces of porous graphene material and the sum of the areas of multiple pieces of porous graphene material, and calculating the ratio of the two, which is the porosity of a single piece of porous graphene material.

[0064] Non-limitingly, the functional layer can be peeled off by disassembling the solid-state battery, placed in N-methylpyrrolidone (NMP) for ultrasonic dispersion, the functional layer material can be retrieved using a copper mesh, the functional layer material can be photographed using a transmission electron microscope (TEM), the maximum pore size of all the porous graphene-like materials in the cross section can be measured, and the average value can be taken to obtain the average pore size of the porous graphene-like material.

[0065] Non-limitingly, the solid-state battery can be discharged to below 10% SOC, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% SOC. The negative electrode layer with the functional layer is then peeled off, and the negative electrode layer is ultrasonically dispersed in deionized water. Subsequently, SEM-EDS is used to determine whether the functional layer contains porous graphene-like materials and other water-insoluble materials. Specifically, a cross-section perpendicular to the thickness direction of the functional layer is randomly cut, and the cross-section is photographed using SEM. Combined with EDS, it is determined whether the functional layer contains other water-soluble materials. The ratio of carbon atoms to other atoms in the cross-section is measured using SEM combined with energy dispersive spectroscopy (EDS), thereby obtaining the mass content of porous graphene-like materials in the functional layer under the condition that the solid-state battery is less than or equal to 10% SOC.

[0066] Unless otherwise stated, the term "solid-state battery" as used in this application refers to a battery in which the electrolyte includes a solid electrolyte.

[0067] In this application, unless otherwise specified, "solid electrolyte" refers to an electrolyte material or substance that exists in solid form during the storage and fabrication of solid-state batteries and their components, 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.

[0068] Solid-state batteries include at least one electrode assembly.

[0069] In this application, unless otherwise specified, "electrode assembly" refers to the basic unit capable of realizing the interconversion of chemical energy and electrical energy, and all its components are solid-state. For non-limiting purposes, please refer to... Figure 1 The electrode assembly 12 may include a positive electrode layer 121, a solid electrolyte layer 122, a functional layer 124, and a negative electrode layer 123. The solid electrolyte layer 122 is located between the positive electrode layer 121 and the functional layer 124, and the functional layer 124 is located between the solid electrolyte layer 122 and the negative electrode layer 123. During battery charging and discharging, active ions are inserted and extracted back and forth between the positive and negative electrode layers. The solid electrolyte layer plays a role in conducting ions between the positive and negative electrode layers and can also isolate the positive and negative electrode layers to prevent short circuits between the positive and negative electrodes.

[0070] Furthermore, the positive electrode layer 121, the solid electrolyte layer 122, the functional layer 124, and the negative electrode layer 123 can constitute an electrode assembly. (See also...) Figure 1 As an example, it only shows two electrode assemblies stacked together along the thickness direction; however, the actual number can be set to one or more as needed. See also Figure 1As an example, the positive electrode layer 121 includes a positive electrode current collector 1211 and a positive electrode active layer 1212 disposed on at least one surface of the positive electrode current collector 1211. As an example, the negative electrode layer 123 includes a negative electrode current collector 1231 and a negative electrode active layer 1232 disposed on at least one surface of the negative electrode current collector 1231.

[0071] In some implementations, the negative electrode layer includes a negative electrode current collector.

[0072] 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).

[0073] In some embodiments, the negative electrode layer only includes a negative electrode current collector. In this case, the negative electrode layer does not contain a negative electrode active layer, and the solid-state battery is a negative electrode-free solid-state battery.

[0074] In some other embodiments, the negative electrode layer further includes a lithium-containing metal layer located on at least one surface of the negative electrode current collector.

[0075] In some embodiments, the lithium-containing metal layer includes one or more of lithium metal and lithium alloy, wherein the non-lithium metal element in the lithium alloy includes one or more of Bi, Ag, Zn, Mg, Sn, In and Al.

[0076] In some implementations, the porosity of the monolithic porous graphene-like material is 3% to 7%. This can further improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage, thereby further improving the cycle performance of the solid-state battery.

[0077] In some embodiments, the porous graphene-like material in the functional layer has a mass content of 94% to 100%. This can further improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage, thereby further improving the cycle performance of the solid-state battery.

[0078] In some implementations, the functional layer does not include an adhesive.

[0079] In some implementations, fluorinated binders are not included in the functional layer. This can further improve the cycle performance of solid-state batteries. Fluorinated binders, such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), may form micelles in the functional layer, leading to uneven conductivity of the functional layer; furthermore, fluorinated binders can react with lithium metal to form fluorides, affecting the cycle stability of solid-state batteries.

[0080] In some embodiments, the average sheet diameter of the porous graphene-like material is 5 μm to 100 μm. Controlling the average sheet diameter of the porous graphene-like material within this range is beneficial for further improving the strength of the functional layer, while also enabling faster lithium-ion transport within the functional layer, which is beneficial for improving the cycle stability of the solid-state battery. As a non-limiting example, the average sheet diameter of the porous graphene-like material includes, but is not limited to: 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, or any range between the foregoing. Further, the average sheet diameter of the porous graphene-like material is 20 μm to 100 μm.

[0081] Non-limitingly, the average sheet diameter of the porous graphene material can be obtained by disassembling the solid-state battery, peeling off the functional layer, ultrasonically dispersing the functional layer in water, observing the area of ​​multiple (>50) porous graphene-like materials using an optical microscope, calculating the radius of the circle corresponding to the area, and taking the average value.

[0082] In some embodiments, the average thickness of the porous graphene-like material is less than or equal to 20 nm. By controlling the average thickness of the porous graphene-like material within the above range, the porous graphene-like material in the functional layer is arranged more densely, which can reduce the risk of lithium dendrite formation at the pores between the porous graphene-like materials. As a non-limiting example, the average thickness of the porous graphene-like material includes, but is not limited to: 0.7 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, or any range between the foregoing. Further, the average thickness of the porous graphene-like material is 0.7 nm to 5 nm.

[0083] In a non-limiting manner, the average thickness of the porous graphene material can be obtained by disassembling a solid-state battery, randomly cutting a cross-section along the thickness direction of the functional layer, using a TEM to photograph the cross-section and measuring the thickness of all porous graphene materials in the cross-section, and taking the average value.

[0084] In some embodiments, porous graphene-like materials include one or more of porous graphene, porous graphene oxide, and porous reduced graphene oxide.

[0085] In some embodiments, the porous graphene-based material includes at least porous reduced graphene oxide. This can further improve the cycle performance of solid-state batteries.

[0086] In some embodiments, the porosity of the functional layer is 3% to 20%. As a non-limiting example, the porosity of the functional layer includes, but is not limited to: 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or any range between the foregoing.

[0087] In some embodiments, the thickness of the functional layer is 100nm to 500nm. This reduces the lithium uptake of the functional layer while simultaneously giving it higher strength, which is beneficial for further improving the cycle performance of the solid-state battery. As a non-limiting example, the thickness of the functional layer includes, but is not limited to: 100nm, 130nm, 150nm, 180nm, 200nm, 230nm, 250nm, 280nm, 300nm, 330nm, 350nm, 380nm, 400nm, 430nm, 450nm, 480nm, 500nm, or any range between the foregoing.

[0088] In some implementations, solid-state batteries include semi-solid-state batteries and all-solid-state batteries.

[0089] In some implementations, the solid-state battery includes an all-solid-state battery. Further, the solid-state battery is an all-solid-state battery.

[0090] It is understandable that a liquid battery refers to a battery in which the electrolyte is liquid. A semi-solid battery is a type of battery that falls between a liquid battery and a fully solid battery. It is mainly based on a liquid battery, but replaces part of the electrolyte with a solid electrolyte.

[0091] 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 layer, negative electrode layer, functional layer and electrolyte part are all made of solid materials, and no liquid electrolyte is provided in the battery, so it can be called "all-solid-state battery".

[0092] In some implementations, the solid-state battery includes a solid-state battery having a stacked structure.

[0093] In some embodiments, the positive electrode layer may be formed based on an etched solid electrolyte membrane or provided by a pre-fabricated positive electrode sheet, which may be a positive electrode sheet that is available in the art for use in solid-state batteries.

[0094] In some embodiments, the positive electrode sheet can be prepared by dry or wet methods. For example, it can be dry-pressed into a film. Alternatively, it can be wet-coated and dried to form a film.

[0095] In some embodiments, the positive electrode layer includes a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector.

[0096] In this application, unless otherwise specified, the positive electrode layer includes at least a positive electrode active layer.

[0097] Unless otherwise stated in this application, the positive electrode sheet includes at least a positive active layer.

[0098] In this application, unless otherwise specified, the positive electrode active layer includes at least positive electrode active particles, and usually also includes positive electrode electrolyte particles.

[0099] In this application, unless otherwise specified, "positive electrode active particles" refers to particles containing positive electrode active substances that have the ability to reversibly extract and insert active ions.

[0100] In this application, unless otherwise specified, "positive electrode electrolyte particles" and "positive electrode solid electrolyte" have the same meaning and can be used interchangeably, referring to solid electrolytes that can be used in the positive electrode layer. Positive electrode electrolyte particles can enhance the ion conductivity of the positive electrode layer, reduce interfacial impedance, and promote the charge transfer efficiency and full release of capacity between the positive electrode active material and the external environment.

[0101] In some embodiments, the positive electrode active material may be a known positive electrode active material for 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. Examples of lithium transition metal oxides 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-containing phosphates with an olivine structure include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium manganese iron phosphate and carbon composites. 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 / 3Mn 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. 0.80 Co 0.15 Al 0.05 O2. Examples of lithium iron phosphate include LiFePO4 (also known as LFP). Examples of lithium manganese phosphate include LiMnPO4.

[0102] Understandably, lithium (Li) is intercalated and deintercalated during the charging and discharging process of a battery, and the Li content in the positive electrode varies depending on the state of discharge. In the exemplary description of the positive electrode active material in this application, unless otherwise specified, the Li content can be the initial state of the material or a non-initial state after charge-discharge cycles. When the positive electrode active material is applied to the positive electrode in a battery system, the Li content in the positive electrode active material at the positive electrode will usually change after charge-discharge cycles. The Li content can be measured in atomic molar content, but is not limited to this. Regarding "Li content is the initial state of the material," the initial state of the material refers to the state before it is formed into the positive electrode active layer. It is understood that new materials or substances obtained by appropriate modification based on the listed positive electrode active materials are also within the scope of positive electrode active materials. The aforementioned appropriate modification refers to an acceptable modification method for the positive electrode active material, and non-limiting examples include coating modification.

[0103] In the exemplary description of the positive electrode active material in this application, the oxygen (O) content is only a theoretical value. Lattice oxygen release will cause changes in the atomic molar content of oxygen, and the actual O content will fluctuate. The O content can be measured using atomic molar content, but is not limited to this.

[0104] Without limitation, the weight percentage of positive electrode active particles or positive electrode active materials in the positive electrode active layer can be ≥70wt%, further ≥80wt%, even further ≥90wt%, and can also be 70wt%~99wt%, optionally 80wt%~95wt%.

[0105] Non-limiting, the weight percentage of positive electrode electrolyte particles in the positive electrode active layer can be 0.1wt% to 30wt%, and optionally 5wt% to 20wt%.

[0106] In some embodiments, the positive electrode active layer includes positive electrode electrolyte particles. Non-limitingly, the weight percentage of the positive electrode electrolyte particles in the positive electrode active layer can be 0.1 wt% to 30 wt%, optionally 5 wt% to 20 wt%.

[0107] In some embodiments, the positive electrode active layer includes positive electrode active particles and positive electrode electrolyte particles.

[0108] In some embodiments, the positive electrode active layer includes a conductive agent (which may be referred to as a positive electrode conductive agent). As a non-limiting example, the positive electrode conductive agent may be a carbon conductive agent. Non-limitingly, the carbon conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the positive electrode conductive agent may include, but is not limited to, one or more of SP, KS-6, acetylene black, branched Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes (CNTs), and graphene. Non-limitingly, the weight percentage of the positive electrode conductive agent in the positive electrode active layer may be 0-10 wt%, more further 0-8 wt%, even further 0-5 wt%, and even further 0.1 wt%-3 wt%. When the positive electrode material is prepared into a positive electrode active layer using a dry method, the positive electrode conductive agent can be incorporated into the positive electrode material, which can improve the conductivity of the positive electrode active layer.

[0109] In some embodiments, the positive electrode active layer optionally includes a binder (which may be referred to as a positive electrode binder). As a non-limiting example, the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. The aforementioned non-limiting examples of positive electrode binders are all organic binders and belong to organic components. Typically, the weight percentage of the positive electrode binder in the positive electrode active layer can be 0-10 wt%, more commonly 0-8 wt%, even more commonly 0.1 wt%-5 wt%, and even more commonly 1 wt%-5 wt%. When the positive electrode material is formulated into a positive electrode slurry using a wet process and then the positive electrode active layer is prepared, the positive electrode binder can be placed in the positive electrode slurry, which can assist in film formation and also promote the formation of a good electrical contact network between the active particles in the positive electrode active layer.

[0110] Non-limiting, the positive electrode active layer may include positive electrode active particles, positive electrode electrolyte particles, positive electrode conductive agent, and positive electrode binder. The types and amounts of each component can be found in the context of this application.

[0111] As a non-limiting example, the positive current collector has two surfaces that are opposite to each other in its own thickness direction, and the positive active layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0112] 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. In the positive electrode current collector, the composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. In the positive electrode current collector, the composite current collector may be obtained by forming a metal material on the polymeric material substrate. Non-limiting examples of the metal material in the positive electrode current collector may include at least one of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limiting examples of the polymeric material substrate in the positive electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0113] In some embodiments, the positive electrode sheet can be prepared by: dry mixing the components used to prepare the positive electrode sheet, 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; hot rolling pressing to form a self-supporting positive electrode sheet; and hot rolling bonding the self-supporting positive electrode sheet with a positive electrode current collector, wherein the self-supporting positive electrode sheet can be bonded to at least one side (single or double sides) of the positive electrode current collector to obtain the positive electrode sheet. Non-limitingly, a dual planetary mixer can be used for dry mixing. Non-limitingly, a kneading and pressing process can be performed using a Banbury mixer. Non-limitingly, the temperature for hot rolling pressing can be 75°C to 85°C, and further, such as 78°C, 80°C, 82°C, etc. The method of assembling solid-state batteries using positive electrode sheets is suitable for industrial mass production.

[0114] In some embodiments, the positive electrode sheet can be prepared by dispersing the components used to prepare the positive electrode sheet, such as positive electrode active particles, positive electrode electrolyte particles, positive electrode conductive agent, positive electrode binder, and any other components, in an organic 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 organic solvent in the positive electrode slurry can include one or more of p-xylene, trimethylbenzene, butyl butyrate, heptane, etc., and more specifically, 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 40wt% to 80wt%. 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 / cm2 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 .

[0115] The term "compacted density" as used in this application has a meaning known in the art and is one of the reference indicators for the energy density of materials. In this application, unless otherwise specified, the compacted density of the positive electrode layer or positive electrode sheet refers to the ratio of the mass of the positive electrode active layer to its volume.

[0116] A solid electrolyte layer can be introduced by forming electrode layers on both sides of the solid electrolyte membrane, or it can be introduced on the electrode layer.

[0117] The solid electrolyte layer acts as a conductor of ions between the positive and negative electrode layers, and can also isolate the positive and negative electrode layers to prevent short circuits between them.

[0118] It is understood that the solid electrolyte layer includes a solid electrolyte. The solid electrolyte in the solid electrolyte layer can be a solid electrolyte known in the art that can be used in solid-state batteries.

[0119] 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 layer and the solid electrolyte layer can be the same or different.

[0120] 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.

[0121] 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 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.

[0122] Solid electrolyte membranes or solid electrolyte layers can be prepared using dry methods. In some embodiments, the solid electrolyte layer can be formed by pressing solid electrolyte materials into a solid electrolyte membrane. In other embodiments, the solid electrolyte layer is formed by pressing the constituent raw materials of the solid electrolyte layer onto an electrode layer. In still other embodiments, the solid electrolyte membrane can also be prepared using methods such as fibrosis combined with calendering, melt extrusion, or spraying.

[0123] In this application, the sheet-like solid electrolyte membrane may also be referred to as a solid electrolyte membrane sheet.

[0124] Solid electrolyte layers can also be prepared using a wet process. 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.

[0125] In some embodiments, the thickness of the solid electrolyte layer can be 0.1 μm to 1000 μm, and can be selected as 10 μm to 100 μm, 100 μm to 800 μm, 500 μm to 800 μm, etc.

[0126] In some embodiments, the solid-state battery may include an outer packaging. This outer packaging may be used to encapsulate the aforementioned electrode assembly.

[0127] 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.

[0128] This application does not impose any particular restrictions on the shape of the solid-state battery; it can be cylindrical, square, or any other arbitrary shape. Figure 2This is an example of a square-structured solid-state battery 1.

[0129] Reference Figure 3 The outer packaging may include a housing 11 and a cover plate 13. The housing 11 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 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be placed over the opening to close the receiving cavity. The electrode assembly 12 is encapsulated within the receiving cavity. The solid-state battery 1 may contain one or more electrode assemblies 12, which can be selected by those skilled in the art according to actual needs.

[0130] In some implementations, solid-state batteries can be individual cells, battery modules, or battery packs.

[0131] The battery module includes at least one solid-state battery. The battery module may contain one or more solid-state batteries, and those skilled in the art can select the appropriate number based on the application and capacity of the battery module.

[0132] In a battery module, multiple solid-state batteries can be arranged sequentially along the length of the module. Alternatively, they can be arranged in any other manner. Furthermore, these multiple solid-state batteries can be secured using fasteners.

[0133] Optionally, the battery module may also include a housing with a receiving space in which multiple solid-state batteries are housed.

[0134] In some embodiments, the battery modules can also be assembled into a battery pack, and the number of battery modules 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.

[0135] The battery pack may include a battery box and multiple battery modules disposed within the battery box. The battery box includes an upper body and a lower body, with the upper body covering the lower body to form a closed space for accommodating the battery modules. The multiple battery modules can be arranged in any manner within the battery box.

[0136] A second aspect of this application provides a method for preparing a solid-state battery. The solid-state battery includes a positive electrode layer, a negative electrode layer, a functional layer disposed on at least one surface of the negative electrode layer, and a solid electrolyte layer disposed between the functional layer and the positive electrode layer. The functional layer includes a porous graphene-like material, wherein the porosity of a single piece of the porous graphene-like material is 3% to 9%, and the average pore size of the porous graphene-like material is 0.2 nm to 15 nm. Under the condition that the solid-state battery has a state of charge (SOC) of less than or equal to 10%, the mass content of the porous graphene-like material in the functional layer is 91% to 100%. The method for preparing the solid-state battery includes the step of preparing the porous graphene-like material.

[0137] The raw materials for graphene-like materials are oxidized to form a porous structure, thus obtaining porous graphene-like materials.

[0138] In the solid-state battery prepared by the above method, a functional layer is set between the negative electrode layer and the solid electrolyte layer. On the one hand, due to the high mechanical properties of porous graphene materials, controlling the porosity of the porous graphene materials in a single piece within the above-mentioned range and controlling the mass content of porous graphene materials in the functional layer within the above-mentioned range under the condition that the solid-state battery is less than or equal to 10% SOC can effectively improve the strength of the functional layer, reduce the risk of lithium dendrites piercing the functional layer near the negative electrode layer, and reduce the risk of functional layer breakage. This effectively isolates the negative electrode layer and the solid electrolyte layer, reducing side reactions between them. On the other hand, controlling the average pore size of the porous graphene materials in the functional layer within the above-mentioned range is beneficial for lithium ions to pass through the functional layer and reach the negative electrode layer. Furthermore, controlling the porosity of the porous graphene materials in a single piece within the above-mentioned range can promote the rapid transport of lithium ions, thereby effectively improving the cycle performance of the solid-state battery.

[0139] In some embodiments, the oxidation treatment temperature is -20°C to 100°C. As a non-limiting example, the oxidation treatment temperature includes, but is not limited to: -20°C, -10°C, 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or any range between the foregoing.

[0140] In some embodiments, the oxidation treatment time is from 1 min to 200 h. As a non-limiting example, the oxidation treatment time includes, but is not limited to: 1 min, 5 min, 30 min, 45 min, 1 h, 3 h, 5 h, 10 h, 20 h, 30 h, 40 h, 50 h, 70 h, 100 h, 120 h, 150 h, 170 h, 200 h, or any range between the foregoing.

[0141] In some embodiments, the oxidant used in the oxidation treatment includes one or more of hydrogen peroxide, nitric acid, ammonia, sulfuric acid, and potassium permanganate.

[0142] In some embodiments, the oxidant used in the oxidation treatment is an oxidizing solution with a mass concentration of 10% to 98%. As a non-limiting example, the mass concentration of the oxidizing solution includes, but is not limited to, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, or any range between the foregoing. In some embodiments, the oxidizing solution includes one or more of hydrogen peroxide, nitric acid, ammonia, sulfuric acid, and potassium permanganate solution.

[0143] In some embodiments, the raw materials for graphene-based materials include one or more of graphene, graphene oxide, and reduced graphene oxide.

[0144] In some embodiments, the oxidation treatment step is followed by a reduction treatment of the product obtained from the oxidation treatment.

[0145] In some embodiments, the reduction treatment temperature is -20°C to 60°C. As a non-limiting example, the reduction treatment temperature includes, but is not limited to: -20°C, -10°C, 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, or any range between the foregoing.

[0146] In some implementations, the reduction process takes 1 minute to 200 hours. As a non-limiting example, the reduction process time includes, but is not limited to: 1 minute, 5 minutes, 30 minutes, 45 minutes, 1 hour, 3 hours, 5 hours, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 70 hours, 100 hours, 120 hours, 150 hours, 170 hours, 200 hours, or any range between the foregoing.

[0147] In some embodiments, the reducing agent used in the reduction process includes one or more of hydrazine hydrate, dimethylhydrazine, hydroquinone, sodium borohydride (NaBH4), and liquid hydrazine.

[0148] In some embodiments, the reducing agent used in the reduction treatment is a reducing solution with a mass concentration of 10% to 98%. As a non-limiting example, the mass concentration of the reducing solution includes, but is not limited to, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, or any range between the foregoing. In some embodiments, the solute in the reducing solution includes one or more of hydrazine, dimethylhydrazine, hydroquinone, and sodium borohydride.

[0149] By controlling at least one of the following: oxidation treatment temperature, oxidation treatment time, type of oxidant, mass concentration of oxidizing solution, reduction treatment temperature, reduction treatment time, type of reducing agent, and mass concentration of reducing solution, the average pore size and porosity of a single porous graphene material can be controlled.

[0150] In some embodiments, the method for fabricating a solid-state battery further includes the step of fabricating a functional layer:

[0151] Porous graphene-like materials are placed on at least one surface of the negative electrode layer or on the solid electrolyte layer.

[0152] In some implementations, the method of setting the coating includes, but is not limited to, at least one of spin coating and vacuum filtration.

[0153] It should be noted that the solid-state battery of the first aspect of this application can be obtained by adjusting the process conditions of the above-mentioned solid-state battery preparation method.

[0154] A third aspect of this application provides an electrical device comprising at least one of the solid-state battery described in the first aspect of this application and a solid-state battery prepared by the method described in the second aspect of this application.

[0155] In some embodiments, the electrical device includes at least one of the solid-state batteries of any of the embodiments provided in this application.

[0156] Without limitation, solid-state batteries can be used as a power source for an electrical device or as an energy storage unit for an electrical device. 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, etc., but are not limited to these.

[0157] As an electrical device, solid-state batteries can be selected based on its usage requirements.

[0158] Figure 4 Here is an example of an electrical device 2. 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, a battery pack or battery module can be used.

[0159] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can be powered by a battery.

[0160] 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.

[0161] The test methods for each embodiment and comparative example are as follows:

[0162] (1) Mass content test of porous graphene-like materials in the functional layer

[0163] The solid-state battery is discharged to below 10% SOC, for example, 5% SOC. The negative electrode layer with the functional layer is peeled off, and the negative electrode layer is ultrasonically dispersed in deionized water. Then, SEM-EDS is used to determine whether the functional layer contains porous graphene-like materials and other water-insoluble materials. Specifically, a cross-section perpendicular to the thickness direction of the functional layer is randomly cut, and the cross-section is photographed using SEM. Combined with EDS, it is determined whether the functional layer contains other water-soluble materials. The ratio of carbon atoms to other atoms in the cross-section is determined using SEM and combined with EDS, thereby obtaining the mass content of porous graphene-like materials in the functional layer under the condition that the solid-state battery is less than or equal to 10% SOC.

[0164] (2) Porosity testing of single-piece porous graphene materials

[0165] The solid-state battery was disassembled, the functional layer was peeled off, and then the functional layer was ultrasonically dispersed in ethanol to separate single porous graphene-like materials. Multiple porous graphene-like materials (>50 pieces) were observed using TEM. The sum of the pore areas of the multiple porous graphene-like materials and the sum of the areas of the multiple porous graphene-like materials were obtained. The ratio of the two was calculated, which is the porosity of a single porous graphene-like material.

[0166] (3) Average pore size test of porous graphene materials

[0167] The functional layer was ultrasonically dispersed in NMP, and the functional layer material was retrieved using a copper mesh. The functional layer material was then photographed using TEM, and the maximum pore size of all the porous graphene-like materials in the cross section was measured. The average value was then taken to obtain the average pore size of the porous graphene-like materials.

[0168] (4) Average thickness test of porous graphene materials

[0169] The solid-state battery was disassembled, and a cross-section along the thickness direction of the functional layer was randomly cut. The cross-section was photographed using TEM, and the thickness of all porous graphene materials in the cross-section was measured. The average value was taken to obtain the average thickness of the porous graphene materials.

[0170] (5) Average sheet diameter test of porous graphene materials

[0171] The solid-state battery was disassembled, the functional layer was peeled off, and the functional layer was ultrasonically dispersed in water. Then, the area of ​​multiple (>50) porous graphene-like materials was observed using an optical microscope, and the radius of the circle corresponding to the area was calculated. The average value was taken to obtain the average sheet diameter of the porous graphene-like materials.

[0172] (6) Porosity testing of functional layers

[0173] The porosity of the functional layer was tested using the conventional gas adsorption method (BET method). At extremely low temperatures (liquid nitrogen temperature, -196°C), the amount of nitrogen adsorbed by the sample under different pressures was measured. The porosity of the functional layer was calculated by analyzing the adsorption-desorption isotherms.

[0174] (7) Cyclic performance test

[0175] At 25°C, the solid-state battery was charged at a constant current rate of 0.5C until the voltage exceeded 4.35V. It was then further charged at a constant voltage of 4.35V until the current dropped below 0.05C, bringing it to a fully charged state at 4.35V. Afterward, the solid-state battery was discharged at a constant current rate of 0.5C until the voltage reached 2V (cutoff voltage). This constitutes one cycle. This cycle was repeated 200 times, and the discharge capacity D1 of the last cycle was recorded. Cycle capacity retention (%) = D1 / D0 × 100%. A higher capacity retention indicates better cycle performance of the solid-state battery.

[0176] Example 1

[0177] The preparation method of solid-state batteries includes the following steps:

[0178] (1) Preparation of functional layers

[0179] (1.1) Dissolve 0.1g of graphene material raw material (graphene powder, average sheet diameter of 50μm, average thickness of 2nm) in 45mL of deionized water and stir, then ultrasonically disperse for 1h to obtain graphene solution.

[0180] (1.2) Add the oxidant (2.5 mL hydrogen peroxide and 2.5 mL ammonia) to the graphene solution prepared in step (1.1) (the volume ratio of hydrogen peroxide, ammonia, and graphene oxide solution is 2.5:2.5:45), mix well, and heat to 40°C while magnetically stirring for 1.5 h for oxidation treatment. Centrifuge the product after the reaction, discard the supernatant, and repeatedly ultrasonically disperse and wash the resulting precipitate with ethanol and deionized water, followed by centrifugation and freeze-drying to obtain graphene oxide; wherein the mass concentration of hydrogen peroxide is 20% and the mass concentration of ammonia is 25%.

[0181] (1.3) The above-mentioned graphene oxide was ultrasonically dispersed in water, and the resulting solution was centrifuged to obtain a few-layer graphene oxide solution. 0.1 g of reducing agent (hydrazine hydrate) was added to the graphene oxide solution, and the mixture was stirred at 90 °C for 2 h. The obtained product was centrifuged, the supernatant was discarded, and the resulting precipitate was washed successively with ethanol and deionized water, and then freeze-dried to obtain porous reduced graphene oxide powder;

[0182] (1.4) The porous reduced graphene oxide powder (porous graphene-like material) obtained in step (1.3) and graphene were ultrasonically dispersed in 40 mL of anhydrous ethanol at a mass ratio of 94:6 for 30 min to obtain a mixed solution; the mixed solution was spin-coated onto the copper foil of the negative electrode current collector to obtain a functional layer with a thickness of 300 nm. In the functional layer, the porosity of the single porous graphene-like material was 5%, the average pore size of the porous graphene-like material was 2 nm, the average sheet diameter of the porous graphene-like material was 50 μm, the average thickness of the porous reduced graphene oxide was 2 nm, and the porosity of the functional layer was 11%.

[0183] (2) Preparation of the positive electrode layer

[0184] The positive electrode active layer in the positive electrode layer includes a positive electrode active material, a sulfide solid electrolyte, a conductive agent, and a binder, and is prepared using a dry method. Specifically, the positive electrode active material NCM... 811 The sulfide solid electrolyte Li6PS5Cl and the conductive agent vapor-grown carbon fiber (VGCF) were uniformly mixed at a mass ratio of 65:33:2 for 10 min to obtain a composite cathode powder. PTFE binder, accounting for 1% of the mass percentage of the composite cathode powder, was added and rolled into a cathode film (cathode layer).

[0185] (3) Preparation of solid electrolyte layer

[0186] The sulfide solid electrolyte Li6PS5Cl was thoroughly mixed with 1% by mass of binder PTFE and rolled into a solid electrolyte membrane (solid electrolyte layer).

[0187] (4) Battery assembly

[0188] The negative electrode current collector, functional layer, solid electrolyte layer, and positive electrode layer are stacked in order from bottom to top. After being subjected to 600MPa isostatic pressing, the resulting electrode assembly is encapsulated in an aluminum-plastic bag to obtain a solid-state battery.

[0189] Examples 2-3

[0190] The preparation method of solid-state batteries is basically the same as in Example 1, except that the mass ratio of porous reduced graphene oxide to graphene in the preparation step (1.4) of the functional layer is changed, thereby changing the mass content of porous graphene-like materials in the functional layer, as shown in Table 1.

[0191] In step (1.4) of Example 2, the mass ratio of porous reduced graphene oxide to graphene is 91:9.

[0192] In step (1.4) of Example 3, only porous reduced graphene oxide was added, and no graphene was added.

[0193] Comparative Example 1

[0194] The preparation method of solid-state batteries is basically the same as in Example 1, except that the mass ratio of porous reduced graphene oxide to graphene in the preparation step (1.4) of the functional layer is changed to 80:20, thereby changing the mass content of porous graphene materials in the functional layer, as shown in Table 1.

[0195] Comparative Example 2

[0196] The preparation method of solid-state batteries is basically the same as in Example 1, except that the average pore size of the porous graphene material in the functional layer is changed by changing the oxidation temperature and oxidation time in the preparation step (1.2) of the functional layer, as shown in Table 1.

[0197] Comparative Example 3

[0198] The preparation method of solid-state batteries is basically the same as in Example 1, except that step (1) is different.

[0199] Specifically, graphene powder (average sheet diameter of 50 μm and average thickness of 2 nm) was ultrasonically dispersed in 40 mL of anhydrous ethanol for 30 min to obtain a mixed solution; the mixed solution was spin-coated onto the negative electrode current collector copper foil to obtain a functional layer with a thickness of 300 nm.

[0200] Comparative Examples 4-5

[0201] The preparation method of solid-state batteries is basically the same as in Example 1, except that the porosity of the single porous graphene material in the functional layer is changed by changing the oxidation temperature and oxidation time in the preparation step (1.2) of the functional layer.

[0202] The test results of Examples 1-3 and Comparative Examples 1-5 are shown in Table 1.

[0203] Table 1

[0204]

[0205] In Table 1, " / " indicates that the substance or parameter does not exist.

[0206] As shown in Table 1, compared with Comparative Examples 1-5, the solid-state batteries of Examples 1-3 have a higher capacity retention rate after 200 cycles. This indicates that the functional layer of the solid-state battery in Examples 1-3 includes porous graphene-like materials. The porosity of a single porous graphene-like material is 3%-9%, and the average pore size of the porous graphene-like material is 0.2nm-15nm. Under the condition that the solid-state battery is less than or equal to 10% SOC, the mass content of porous graphene-like materials in the functional layer is 91%-100%, which can effectively improve the cycle performance of the solid-state battery.

[0207] Examples 4-7

[0208] The preparation method of solid-state batteries is basically the same as in Example 1, except that the porosity of the single porous graphene material is changed by changing the temperature and / or time of the oxidation treatment in step (1.2) of the preparation of the functional layer, as shown in Table 2.

[0209] Table 2

[0210]

[0211] As shown in Table 2, adjusting the porosity of monolithic porous graphene materials within a suitable range can further improve the cycle performance of solid-state batteries.

[0212] Examples 8-11

[0213] The preparation method of solid-state batteries is basically the same as in Example 1, except that the average sheet diameter of the graphene powder in the preparation step (1.1) of the functional layer is changed, thereby changing the average sheet diameter of the porous graphene material in the functional layer, as shown in Table 3.

[0214] Table 3

[0215]

[0216] As shown in Table 3, adjusting the average sheet diameter of porous graphene materials within a suitable range can further improve the cycle performance of solid-state batteries.

[0217] The descriptions of the various implementation methods and embodiments above tend to emphasize the differences between them. Similarities or resemblances can be referenced interchangeably, and for the sake of brevity, they will not be repeated here. The technical features of the implementation methods and embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combinations of these technical features do not contradict each other, they should be considered within the scope of this specification.

[0218] It should be noted that this application is not limited to the above-described embodiments and examples. The above-described embodiments and examples are merely examples, and any embodiments and examples that have the same structure and achieve the same effect as the technical concept within the scope of this application are included in the technical scope of this application. The embodiments and examples described above only illustrate several embodiments and examples of this application, and although the descriptions are relatively detailed, they should not be construed as limiting the scope of the patent. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments or examples, and other ways of constructing embodiments or examples by combining some of the constituent elements of the embodiments or examples, are also included in the scope of this application without departing from the spirit of this application.

Claims

1. A solid-state battery, characterized in that, The battery comprises a positive electrode layer, a negative electrode layer, a functional layer disposed on at least one surface of the negative electrode layer, and a solid electrolyte layer disposed between the functional layer and the positive electrode layer. The functional layer comprises a porous graphene-like material, wherein the porosity of a single piece of the porous graphene-like material is 3% to 9%, and the average pore size of the porous graphene-like material is 0.2 nm to 15 nm. Under the condition that the solid-state battery is less than or equal to 10% SOC, the mass content of the porous graphene-like material in the functional layer is 91% to 100%.

2. The solid-state battery according to claim 1, characterized in that, The porosity of a single porous graphene-like material is 3% to 7%.

3. The solid-state battery according to claim 1 or 2, characterized in that, The porous graphene-like material in the functional layer has a mass content of 94% to 100%.

4. The solid-state battery according to claim 1 or 2, characterized in that, The solid-state battery has one or more of the following characteristics: (1) The average sheet diameter of the porous graphene material is 5 μm to 100 μm; (2) The average thickness of the porous graphene material is less than or equal to 20 nm.

5. The solid-state battery according to claim 1 or 2, characterized in that, The solid-state battery has one or more of the following characteristics: (1) The average sheet diameter of the porous graphene material is 20 μm to 100 μm; (2) The average thickness of the porous graphene material is 0.7 nm to 5 nm.

6. The solid-state battery according to claim 1 or 2, characterized in that, The porous graphene materials include one or more of porous graphene, porous graphene oxide, and porous reduced graphene oxide.

7. The solid-state battery according to claim 1 or 2, characterized in that, The solid-state battery has one or more of the following characteristics: (1) The porosity of the functional layer is 3%~20%; (2) The thickness of the functional layer is 100nm~500nm.

8. A method for preparing a solid-state battery, characterized in that, The solid-state battery includes a positive electrode layer, a negative electrode layer, a functional layer disposed on at least one surface of the negative electrode layer, and a solid electrolyte layer disposed between the functional layer and the positive electrode layer. The functional layer comprises a porous graphene-like material, with a porosity of 3% to 9% for a single sheet of the porous graphene-like material and an average pore size of 0.2 nm to 15 nm. Under the condition that the solid-state battery has a state of charge (SOC) of less than or equal to 10%, the mass content of the porous graphene-like material in the functional layer is 91% to 100%. The method for preparing the solid-state battery includes the step of preparing the porous graphene-like material. The raw materials for graphene-like materials are oxidized to form a porous structure, thereby obtaining the porous graphene-like material.

9. The method for preparing a solid-state battery according to claim 8, characterized in that, The preparation method satisfies one or more of the following conditions: (1) The oxidation treatment temperature is -20℃ to 100℃; (2) The oxidation treatment time is 1 min to 200 h; (3) The oxidants used in the oxidation treatment include one or more of hydrogen peroxide, nitric acid, ammonia, sulfuric acid and potassium permanganate; (4) The raw materials of the graphene-based materials include one or more of graphene, graphene oxide and reduced graphene oxide.

10. The method for preparing a solid-state battery according to claim 8 or 9, characterized in that, The oxidation process is followed by a reduction process on the product obtained from the oxidation process.

11. The method for preparing a solid-state battery according to claim 10, characterized in that, The reduction process has one or more of the following characteristics: (1) The temperature for the reduction treatment is -20℃ to 60℃; (2) The reduction treatment time is 1 min to 200 h; (3) The reducing agents used in the reduction treatment include one or more of hydrazine hydrate, dimethylhydrazine, hydroquinone, sodium borohydride and liquid hydrazine.

12. An electrical appliance, characterized in that, It includes at least one of the solid-state batteries according to any one of claims 1 to 7 and solid-state batteries prepared by the method of preparing solid-state batteries according to any one of claims 8 to 11.

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