Composite solid electrolyte, preparation method thereof, battery and electric equipment

Abstract

The invention relates to a composite solid electrolyte, a preparation method thereof, a composite solid electrolyte membrane and a battery. The composite solid electrolyte comprises a three-dimensional MXene material and a solid electrolyte, the three-dimensional MXene material has a porous structure, the solid electrolyte comprises a sulfide solid electrolyte or a halide solid electrolyte, and the solid electrolyte is loaded on the three-dimensional MXene material. The composite solid electrolyte not only has relatively high ionic conductivity, but also has relatively good air stability and relatively good mechanical strength.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a composite solid electrolyte and a preparation method thereof, a composite solid electrolyte membrane and a battery. Background Art

[0002] Solid electrolytes such as sulfide solid electrolytes and halide solid electrolytes are considered core materials for the next generation of all-solid-state batteries due to their ultra-high room-temperature lithium-ion conductivity, excellent ductility, and close solid-solid contact with electrode materials. Compared with oxide solid electrolytes with low mechanical strength and polymer electrolytes with low ionic conductivity, solid electrolytes such as sulfide solid electrolytes (SSEs) and halide solid electrolytes can achieve high ion transport efficiency within a wide temperature range of -30 to 100°C. They also have low hot pressing temperatures (<300°C), making them more conducive to large-scale production.

[0003] However, solid electrolytes such as sulfide solid electrolytes (SSE) and halide solid electrolytes have the bottleneck problem of being sensitive to water and oxygen. They easily react with H2O / O2 in the air to generate H2S or hydrogen halide (e.g., HF, HCl) gas and LiOH / Li2CO3 insulating layer, resulting in a decrease in ionic conductivity of more than 90%. To address this problem, the intrinsic stability of solid electrolytes such as sulfide solid electrolytes (SSE) and halide solid electrolytes is often improved by coating and doping, but the existing optimization strategies have significant limitations. For example, although the use of inert layers such as LiF and Li3N to coat solid electrolytes such as sulfide solid electrolytes (SSE) and halide solid electrolytes can improve air stability, when the coating layer thickness exceeds 5nm, the interfacial impedance (>200Ω·cm) will be greatly increased. 2 ), resulting in a decrease in battery rate performance; and although the release of H2S or hydrogen halide (such as HCl) can be suppressed by partially replacing the S element or halogen element in solid electrolytes such as sulfide solid electrolytes (SSE) and halide solid electrolytes with O, excessive doping will reduce the ionic conductivity.

[0004] Moreover, the mechanical strength of molded pure sulfide solid electrolytes (SSE), halide solid electrolytes and other solid electrolytes is insufficient, resulting in some problems when solid electrolytes such as sulfide solid electrolytes (SSE) and halide solid electrolytes are used in all-solid-state batteries. For example, during the charging and discharging process of all-solid-state batteries, when the volume expansion of the positive and negative active materials produces local stress concentration, solid electrolytes such as sulfide solid electrolytes (SSE) and halide solid electrolytes are prone to microcrack expansion, destroying the solid-solid contact interface between the electrolyte and the electrode, resulting in a surge in interfacial impedance and an increased risk of lithium dendrite penetration. Summary of the Invention

[0005] Based on this, it is necessary to provide a composite solid electrolyte that has both good and high ionic conductivity as well as good air stability and good mechanical strength.

[0006] The present invention provides a composite solid electrolyte, comprising a three-dimensional MXene material and a solid electrolyte, wherein the three-dimensional MXene material has a porous structure, the solid electrolyte comprises a sulfide solid electrolyte or a halide solid electrolyte, and the solid electrolyte is loaded on the three-dimensional MXene material.

[0007] In one embodiment, the three-dimensional MXene material has the general chemical formula M n+1 X n Tx, n is a natural number of 1-3, M is a transition metal element, X is a carbon or nitrogen element, Tx is a surface functional group, and Tx includes a -F surface functional group; and / or

[0008] The mass percentage of the solid electrolyte is 80-95%, and the mass percentage of the three-dimensional MXene material is 5-20%; and / or

[0009] The pore filling rate of the three-dimensional MXene material is greater than or equal to 80%; and / or

[0010] A chemical bond is formed between the three-dimensional MXene material and the solid electrolyte; and / or

[0011] The pore size of the three-dimensional MXene material is 50-200 nm, and the particle size of the solid electrolyte is 30-150 nm.

[0012] In one embodiment, the three-dimensional MXene material is Ti3C2Tx or Mo2CTx, and the sulfide solid electrolyte includes Li6PS5Cl, Li7P3S 11 or Li 10 GeP2S 12 .

[0013] In one embodiment, the particle size of the three-dimensional MXene material is in the micrometer scale, and the particle size of the solid electrolyte is in the nanometer scale.

[0014] The present invention also provides a method for preparing the composite solid electrolyte, which is characterized by comprising the following steps:

[0015] Provide solid-state electrolytes and three-dimensional MXene materials;

[0016] adding a solid electrolyte to a solvent to obtain a suspension;

[0017] Immersing the three-dimensional MXene material in the suspension and performing vacuum-assisted impregnation to obtain a mixed solution in which the solid electrolyte is supported on the three-dimensional MXene; and

[0018] The mixed solution is vacuum dried to obtain a composite solid electrolyte.

[0019] In one embodiment, the solvent is acetonitrile, and the concentration of the solid electrolyte in the suspension is 150-250 mg / mL; and / or

[0020] The number of vacuum-assisted impregnation is 3 to 5 times, the vacuum degree of vacuum-assisted impregnation is -0.07 to -0.12 MPa, and the time of vacuum-assisted impregnation is 20 to 30 minutes; and / or

[0021] The temperature of the vacuum drying is 50 to 70° C., the vacuum degree of the vacuum drying is -0.07 to -0.12 MPa, and the time of the vacuum drying is 8 to 20 hours.

[0022] In one embodiment, the method for preparing the three-dimensional MXene material comprises the following steps:

[0023] MXene was added to deionized water and ultrasonically treated to obtain a MXene dispersion;

[0024] The MXene dispersion is injected into the three-dimensional porous template and subjected to freezing treatment to obtain the initial three-dimensional MXene material supported in the three-dimensional porous template;

[0025] freeze-drying the initial three-dimensional MXene material supported in the three-dimensional porous template to obtain the three-dimensional MXene material supported in the three-dimensional porous template; and

[0026] The three-dimensional porous template and the three-dimensional Mxene material are separated to obtain the three-dimensional Mxene material.

[0027] In one embodiment, the concentration of the MXene dispersion is 2 to 10 mg / mL; and / or

[0028] The power of the ultrasonic treatment is 200 to 400 W, and the time of the ultrasonic treatment is 1 to 3 hours; and / or

[0029] The pore size of the three-dimensional porous template is 50 to 200 μm; and / or

[0030] The three-dimensional porous template is a polyurethane template; and / or

[0031] The freezing temperature of the freezing treatment is -60°C to -100°C, the cooling rate of the freezing treatment is 2 to 10°C / min, the freezing treatment time is 12 to 36 hours, and the vacuum degree of the freezing treatment is less than or equal to 10 Pa; and / or

[0032] The freeze-drying temperature is -60°C to -100°C, and the freeze-drying time is 36 to 60 hours.

[0033] The present invention also provides a battery comprising the composite solid electrolyte.

[0034] The present invention also provides an electrical device, characterized in that it includes the above-mentioned battery.

[0035] According to the experimental results, the composite solid electrolytes (Examples 1-6 or Examples 7-12) have significantly improved ionic conductivity, air stability, and mechanical strength compared to the sulfide solid electrolytes (Comparative Example 2) or halide solid electrolytes (Comparative Example 4). Possible theories corresponding to this experimental result are as follows:

[0036] The three-dimensional Mxene material is assembled from Mxene nanosheets (two-dimensional Mxene material) and is a three-dimensional porous material with high porosity and high specific surface area, which enables the three-dimensional Mxene material to load a solid electrolyte. At the same time, because the three-dimensional Mxene material has metal-like conductivity, the three-dimensional Mxene material can provide an ion conductive network, and the solid electrolyte can provide the main channel for lithium ion transmission. The two work in coordination, so that the above-mentioned composite solid electrolyte has a higher ionic conductivity. Moreover, compared with the method of forming a coating layer outside the solid electrolyte, the method of loading the solid electrolyte on the three-dimensional Mxene material with metal-like conductivity does not increase the interfacial impedance, so the above-mentioned composite solid electrolyte also has good battery rate performance.

[0037] At the same time, because the three-dimensional Mxene material is a three-dimensional porous material, the three-dimensional Mxene material can form a tortuous diffusion path and has a three-dimensional maze effect, which prolongs the time for H2O / O2 to penetrate into the solid electrolyte. Therefore, the above-mentioned composite solid electrolyte has good air stability, which to a certain extent solves the air sensitivity problem of solid electrolytes such as sulfide solid electrolytes and halide solid electrolytes.

[0038] When the composite solid electrolyte is subjected to stress, the three-dimensional MXene material can distribute the local stress throughout the entire material, resulting in relatively small local strain under pressure and reducing the probability of cracking. Furthermore, the three-dimensional MXene material absorbs energy through the elastic deformation of its porous, cross-linked network, preventing brittle fracture and inhibiting crack propagation, thereby preventing through-cracks. Therefore, the composite solid electrolyte possesses excellent mechanical strength, addressing, to a certain extent, the interfacial failure issues common in solid electrolytes such as sulfide and halide solid electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0040] Figure 1 This is a schematic structural diagram of a composite solid electrolyte according to an embodiment of the present invention;

[0041] Figure 2 This is a flow chart of a method for preparing a composite solid electrolyte according to an embodiment of the present invention;

[0042] Figure 3 This is a flow chart of a method for preparing a three-dimensional Mxene material according to one embodiment of the present invention;

[0043] Figure 4 Schematic diagram of the structure of a testing device for the 24-hour release of H2S according to one embodiment of the present invention. DETAILED DESCRIPTION

[0044] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0045] In the description of the present application, it should be understood that, if any, terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0046] Furthermore, if used, the terms "first" and "second," if present, are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0047] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connected," and "fixed" should be interpreted broadly. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components, unless otherwise expressly limited. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0048] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0049] It should be noted that, if present, when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0050] like Figure 1 As shown, a composite solid electrolyte provided by one embodiment of the present invention includes a three-dimensional MXene material and a solid electrolyte. The three-dimensional MXene material has a porous structure. The solid electrolyte is supported on the three-dimensional MXene material. The solid electrolyte includes a sulfide solid electrolyte or a halide solid electrolyte.

[0051] According to the experimental results, the composite solid electrolytes (Examples 1-6 or Examples 7-12) have significantly improved ionic conductivity, air stability, and mechanical strength compared to the sulfide solid electrolytes (Comparative Example 2) or halide solid electrolytes (Comparative Example 4). Possible theories corresponding to this experimental result are as follows:

[0052] The three-dimensional Mxene material is assembled from Mxene nanosheets (two-dimensional Mxene material) and is a three-dimensional porous material with high porosity and high specific surface area, which enables the three-dimensional Mxene material to load a solid electrolyte. At the same time, because the three-dimensional Mxene material has metal-like conductivity, the three-dimensional Mxene material can provide an ion conductive network, and the solid electrolyte can provide the main channel for lithium ion transmission. The two work in coordination, so that the above-mentioned composite solid electrolyte has a higher ionic conductivity. Moreover, compared with the method of forming a coating layer outside the solid electrolyte, the method of loading the solid electrolyte on the three-dimensional Mxene material with metal-like conductivity does not increase the interfacial impedance, so the above-mentioned composite solid electrolyte also has good battery rate performance.

[0053] At the same time, because the three-dimensional Mxene material is a three-dimensional porous material, the three-dimensional Mxene material can form a tortuous diffusion path and has a three-dimensional maze effect, which prolongs the time for H2O / O2 to penetrate into the solid electrolyte. Therefore, the above-mentioned composite solid electrolyte has good air stability, which to a certain extent solves the air sensitivity problem of solid electrolytes such as sulfide solid electrolytes and halide solid electrolytes.

[0054] When the composite solid electrolyte is subjected to stress, the three-dimensional MXene material can distribute the local stress throughout the entire material, resulting in relatively small local strain under pressure and reducing the probability of cracking. Furthermore, the three-dimensional MXene material absorbs energy through the elastic deformation of its porous, cross-linked network, preventing brittle fracture and inhibiting crack propagation, thereby preventing through-cracks. Therefore, the composite solid electrolyte possesses excellent mechanical strength, addressing, to a certain extent, the interfacial failure issues common in solid electrolytes such as sulfide and halide solid electrolytes.

[0055] In this embodiment, the chemical formula of the three-dimensional MXene material is M n+1 X n Tx, n is a natural number of 1-3, M is a transition metal element, X is a carbon or nitrogen element, Tx is a surface functional group, and Tx includes a -F surface functional group. The -F surface functional group has hydrophobic properties. The hydrophobic surface functional group of the three-dimensional MXene material can physically block the adsorption of H2O on the solid electrolyte, significantly inhibiting the adsorption of H2O on the solid electrolyte surface, thereby making the above-mentioned composite solid electrolyte have better air stability. It is understood that in other embodiments, Tx may also include other hydrophobic surface functional groups in addition to the -F surface functional group.

[0056] In this embodiment, a chemical bond is formed between the three-dimensional MXene material and the solid electrolyte. The metal (Ti, Mo, etc.) in the three-dimensional MXene material and the sulfur element in the sulfide solid electrolyte or the halogen element in the halide solid electrolyte may undergo an interfacial chemical reaction. This interfacial chemical reaction, based on the intrinsic chemical activity of the three-dimensional MXene material and the sulfide solid electrolyte or halide solid electrolyte, is an in-situ spontaneous chemical bonding that can form stable metal-sulfur chemical bonds (Ti-S, Mo-S, etc.) or metal-halogen chemical bonds (Ti-Cl, Mo-Cl, etc.), thereby making the sulfide solid electrolyte or halide solid electrolyte more stably loaded on the three-dimensional MXene material.

[0057] In this embodiment, the particle size of the three-dimensional MXene material is micron-scale, and the particle size of the solid electrolyte is nanometer-scale. The three-dimensional MXene material is a micron-scale structure, which can represent the macroscale. The surface group Tx (hydrophobic group) of the three-dimensional MXene can represent the microscale. The metal-sulfur chemical bond or metal-halide chemical bond that may be formed between the three-dimensional MXene and the solid electrolyte can represent the molecular scale, so that the composite solid electrolyte can synergistically solve the air sensitivity and interface failure problems of sulfide solid electrolytes or halide solid electrolytes at the molecular-micro-macroscopic multi-scale. This multi-scale modification path is significantly different from the traditional "coating-doping" single modification path. Specifically, in this embodiment, the particle size of the three-dimensional MXene material is 50-200μm, and the particle size of the solid electrolyte is 30-150nm.

[0058] In this embodiment, the pore filling rate of the three-dimensional MXene material in the composite solid electrolyte is greater than or equal to 80%. In this way, the three-dimensional MXene material with a smaller mass can load the solid electrolyte with a larger mass, thereby avoiding the situation where there are too few main channels for lithium ion transmission due to too little solid electrolyte. Specifically, in this embodiment, the pore filling rate of the three-dimensional MXene material in the composite solid electrolyte is greater than or equal to 90%. More specifically, in this embodiment, the pore filling rate of the three-dimensional MXene material in the composite solid electrolyte is greater than or equal to 95%.

[0059] In this embodiment, the pore size of the three-dimensional MXene material is 50-200 nm, and the particle size of the solid electrolyte is 30-150 nm. This greatly facilitates the filling of the solid electrolyte into the pores of the three-dimensional MXene material. Specifically, in this embodiment, the pore size of the three-dimensional MXene material is 80-150 nm, and the particle size of the solid electrolyte is 40-70 nm. More specifically, in this embodiment, the pore size of the three-dimensional MXene material is 90-120 nm, and the particle size of the solid electrolyte is 50-60 nm.

[0060] In this embodiment, the mass percentage of the solid electrolyte is 80-95%, and the mass percentage of the three-dimensional MXene material is 5-20%. According to Examples 1-6 or Examples 7-12, when the content of the three-dimensional MXene material is less than 5wt%, for example, when the content of the three-dimensional MXene material is 3wt% (Example 1 or Example 7), the ionic conductivity, air stability and mechanical strength of the composite solid electrolyte are significantly reduced, and are comparable to the ionic conductivity, air stability and mechanical strength of the solid electrolyte (Comparative Example 1 or Comparative Example 3). When the content of the three-dimensional MXene material is greater than 20wt%, for example, when the content of the three-dimensional MXene material is 25wt% (Example 6 or Example 12), the ionic conductivity, air stability and mechanical strength of the composite solid electrolyte are significantly reduced, and are comparable to the ionic conductivity, air stability and mechanical strength of the solid electrolyte (Comparative Example 1 or Comparative Example 3). Possible theories corresponding to this experimental result are as follows:

[0061] When the content of the three-dimensional Mxene material is less than 5wt%, the low content of the three-dimensional Mxene material will lead to very limited improvement in ionic conductivity, air stability and mechanical strength. When the content of the three-dimensional Mxene material is greater than 20wt%, the high content of the three-dimensional Mxene material will lead to too little solid electrolyte, resulting in a decrease in ionic conductivity, air stability and mechanical strength, which is consistent with the percolation theory threshold.

[0062] In this embodiment, the three-dimensional MXene material is Ti3C2Tx. It is understood that in other embodiments, the three-dimensional MXene material can also be Mo2CTx. In this embodiment, the sulfide solid electrolyte includes Li6PS5Cl. It is understood that in other embodiments, the sulfide solid electrolyte can also include Li7P3S 11 or Li 10 GeP2S 12 In this embodiment, the halide solid electrolyte includes Li3YCl6. It is understood that in other embodiments, the halide solid electrolyte may also include Li3InCl6 or Li3ScCl6.

[0063] like Figure 2 As shown, the present invention also provides a method for preparing a composite solid electrolyte, comprising the following steps:

[0064] Step S210: providing a solid electrolyte and a three-dimensional MXene material.

[0065] Step S220: adding the solid electrolyte to the solvent to obtain a suspension.

[0066] In step S230 , the three-dimensional MXene material is immersed in the suspension and vacuum-assisted impregnation is performed to obtain a mixed solution in which the solid electrolyte is loaded on the three-dimensional MXene.

[0067] Step S240: vacuum drying the mixed solution to obtain a composite solid electrolyte.

[0068] The composite solid electrolytes (Examples 1-6 or Examples 7-12) have significant improvements in ionic conductivity, air stability, and mechanical strength compared to the sulfide solid electrolytes (Comparative Example 2) or halide solid electrolytes (Comparative Example 4). The three-dimensional MXene material is assembled from MXene nanosheets (two-dimensional MXene material) and is a three-dimensional porous material with high porosity and high specific surface area. Vacuum-assisted impregnation allows the solid electrolyte to enter the pores of the three-dimensional MXene material, achieving solid electrolyte loading on the three-dimensional MXene material. During the vacuum-assisted impregnation process, the metal elements in the three-dimensional MXene material and the sulfur elements in the sulfide solid electrolyte (or the halogen elements in the halide solid electrolyte) can approach each other through electrostatic attraction or weak coordination bonds. After the mixed solution is vacuum-dried to remove the solvent, the metal elements in the three-dimensional MXene material and the sulfur elements in the sulfide solid electrolyte (or the halogen elements in the halide solid electrolyte) can be in close contact. The close contact triggers local metal-sulfur chemical bonds (or metal-halogen chemical bonds), such as Ti-S and Mo-S; thereby making the sulfide solid electrolyte (or halide solid electrolyte) more stably loaded on the three-dimensional MXene material.

[0069] In this embodiment, in step S210, the solid electrolyte is purchased nanopowder.

[0070] In this embodiment, in step S210, Figure 3 As shown, the preparation method of three-dimensional MXene material includes the following steps:

[0071] In step S211, MXene is added to deionized water and ultrasonically treated to obtain a MXene dispersion.

[0072] In step S212, the MXene dispersion is injected into the three-dimensional porous template, and the MXene dispersion is subjected to freezing treatment to obtain an initial three-dimensional MXene material supported in the three-dimensional porous template.

[0073] Step S213: freeze-drying the initial three-dimensional MXene material supported in the three-dimensional porous template to obtain the three-dimensional MXene material supported in the three-dimensional porous template.

[0074] Step S214, separating the three-dimensional porous template and the three-dimensional MXene material to obtain the three-dimensional MXene material.

[0075] In this embodiment, in the MXene dispersion, MXene is a two-dimensional nanosheet. When preparing a three-dimensional MXene material, the MXene dispersion is first injected into a three-dimensional porous template and then frozen. During the freezing process, deionized water forms ice crystals in the pores of the three-dimensional porous template, and the two-dimensional nanosheets MXene self-assemble (stack and / or cross-link) to form an initial three-dimensional MXene material with a porous structure (the porous structure of the initial three-dimensional MXene material is filled with ice crystals). It is then freeze-dried to remove the ice crystals, so that the initial three-dimensional MXene material becomes a three-dimensional MXene material (the porous structure of the three-dimensional MXene material is in an idle state and not occupied by ice crystals). After deionized water freezes and turns into ice crystals, its volume increases (with a volume expansion rate of approximately 9%), causing the three-dimensional porous template to be squeezed by the expansion stress. When the elastic modulus of the three-dimensional porous template is low (for example, when the elastic modulus is less than MPa, specifically, it can be a polyurethane template), the microstructure of the three-dimensional porous template (such as the pore walls and cross-linking points) will break or deform due to stress concentration. When the ice crystals sublime, the three-dimensional porous template originally supported by the ice crystals becomes a loose porous structure. The three-dimensional porous template loosely detaches due to the loss of support. The three-dimensional porous template and the three-dimensional MXene material can be separated by shaking or other methods.

[0076] During the freezing process, the MXene nanosheets (two-dimensional MXene materials) will self-assemble (stack and / or cross-link) to form an initial three-dimensional MXene material with a porous structure. At this time, the pore walls of the three-dimensional porous template have a guiding effect on the self-assembly of the MXene nanosheets (two-dimensional MXene materials), which is conducive to controlling the particle size of the three-dimensional MXene material and the pore size of the three-dimensional MXene material. Therefore, the use of a three-dimensional porous template to prepare a three-dimensional MXene material is more conducive to controlling the particle size of the three-dimensional MXene material and the pore size of the three-dimensional MXene material than the use of a cold template method to prepare a three-dimensional MXene material (omitting the three-dimensional porous template and directly freezing the MXene dispersion). It can be understood that in other embodiments, the cold template method can also be used to prepare a three-dimensional MXene material.

[0077] In this embodiment, in step S211, the raw material for preparing MXene is Ti3AlC2 or Mo2GaC MAX phase powder (D50 particle size is less than or equal to 40 μm). In the process of preparing MXene, the raw material is added to a mixed solution of hydrofluoric acid (HF, concentration 40 wt%) and LiF (HF:LiF = 5:1 molar ratio), stirred at 50°C for 24 hours, and the Al layer or Ga layer is removed to generate Ti3C2T x MXene or Mo2CT xMXene; after stirring, the solution is centrifuged and washed until the pH is >6, and the precipitate is removed to obtain MXene. The raw material Ti3AlC2 or Mo2GaC MAX phase powder can be purchased directly. It should be noted that the MXene in step S211 is an existing material and can also be produced using existing methods.

[0078] In this embodiment, in step S211, the concentration of the MXene dispersion is 2 to 10 mg / mL. Specifically, in this embodiment, the concentration of the MXene dispersion is 4 to 6 mg / mL. More specifically, in this embodiment, the concentration of the MXene dispersion is 5 mg / mL.

[0079] In this embodiment, in step S211, the ultrasonic treatment power is 200-400 W, and the ultrasonic treatment time is 1-3 hours. Specifically, in this embodiment, the ultrasonic treatment power is 250-350 W, and the ultrasonic treatment time is 1.5-2.5 hours. More specifically, in this embodiment, the ultrasonic treatment power is 300 W, and the ultrasonic treatment time is 2 hours.

[0080] In this embodiment, in step S212, the three-dimensional porous template is a polyurethane template. The polyurethane template has a low elastic modulus, which facilitates the separation of the three-dimensional porous template and the three-dimensional MXene material. In addition, the polyurethane template can be stably prepared using a commercial foaming process at a relatively low cost.

[0081] In this embodiment, in step S212, the pore size of the three-dimensional porous template is 50 to 200 μm. This is conducive to controlling the particle size of the three-dimensional MXene material to be micron-level, and at the same time, it is conducive to controlling the pore size of the three-dimensional MXene material to be 50 to 200 nm. Specifically, in this embodiment, in step S212, the pore size of the three-dimensional porous template is 80 to 150 μm. This is conducive to controlling the pore size of the three-dimensional MXene material to be 80 to 150 nm. More specifically, in this embodiment, in step S212, the pore size of the three-dimensional porous template is 90 to 120 μm (for example, 100 μm). This is conducive to controlling the pore size of the three-dimensional MXene material to be 90 to 120 nm (for example, 100 nm).

[0082] In this embodiment, the freezing temperature of the freezing treatment is -60°C to -100°C, the cooling rate of the freezing treatment is 2 to 10°C / min, the freezing time is 12 to 36 hours, and the vacuum degree of the freezing treatment is less than or equal to 10 Pa. In this way, it is beneficial to control the pore size of the three-dimensional MXene material to be 50 to 200 nm. Specifically, in this embodiment, the freezing temperature of the freezing treatment is -75°C to -85°C (for example, -80°C), the cooling rate of the freezing treatment is 4 to 6°C / min (for example, 5°C / min), and the freezing time is 20 to 28 hours (for example, 24 hours).

[0083] In this embodiment, the freeze-drying temperature is -60°C to -100°C, and the freeze-drying time is 36 to 60 hours. Specifically, in this embodiment, the freeze-drying temperature is -75°C to -85°C (for example, -80°C), and the freeze-drying time is 40 to 56 hours (for example, 48 hours).

[0084] In the present embodiment, in step S220, the solvent is acetonitrile. The solubility of acetonitrile to three-dimensional MXene materials and sulfide solid electrolytes (or halide solid electrolytes) is very low, which can avoid material dissolution losses and also avoid destroying the structure of the three-dimensional MXene material. Acetonitrile can also stably disperse the material to form a stable suspension, avoid material agglomeration, and affect the sulfide solid electrolyte (or halide solid electrolyte) to be loaded on the three-dimensional MXene material. Moreover, the volatility of acetonitrile is moderate, which is convenient for subsequent vacuum drying to remove residues and avoid solvent residues affecting the performance of the composite solid electrolyte. It will be understood that in other embodiments, the solvent is not limited to acetonitrile, and can be any solvent that has low solubility to the material and can stably disperse the material, for example, tetrahydrofuran.

[0085] In this embodiment, in step S220, in the suspension, the concentration of the solid electrolyte is 150-250 mg / mL (for example, 200 mg / mL). If the concentration of the sulfide solid electrolyte (or halide solid electrolyte) is too low, it will affect the efficiency of the sulfide solid electrolyte (or halide solid electrolyte) loaded on the three-dimensional Mxene material. It is necessary to increase the total time of the vacuum-assisted impregnation so that most of the sulfide solid electrolyte (or halide solid electrolyte) is loaded on the three-dimensional Mxene material, resulting in an extension of the preparation time. If the concentration of the sulfide solid electrolyte (or halide solid electrolyte) is too high, the viscosity of the suspension will increase, the fluidity will decrease, and the material agglomeration problem will easily occur, affecting the sulfide solid electrolyte (or halide solid electrolyte) loaded on the three-dimensional Mxene material. Taking the above factors into consideration, after selecting acetonitrile as the solvent, the concentration of the sulfide solid electrolyte (or halide solid electrolyte) is set to 150-250 mg / mL. It can be understood that in other embodiments, when the solvent is changed, the concentration of the sulfide solid electrolyte (or halide solid electrolyte) may also change slightly.

[0086] In this embodiment, in step S230, the number of vacuum-assisted impregnations is 3 to 5 times (for example, 3 times), the vacuum degree of the vacuum-assisted impregnation is -0.07 to -0.12 MPa (for example, -0.1 MPa), and the time of the vacuum-assisted impregnation is 20 to 30 minutes (for example, 30 minutes). Compared to immersing the three-dimensional MXene material in the suspension and then performing a long vacuum-assisted impregnation, repeatedly immersing the three-dimensional MXene material in the suspension and performing a relatively short vacuum-assisted impregnation after each immersion can complete the loading of most of the sulfide solid electrolyte on the three-dimensional MXene material more quickly (for example, the pore filling rate of the three-dimensional MXene material is greater than or equal to 95%), thereby shortening the preparation time of the composite solid electrolyte. However, the number of vacuum-assisted impregnations is too many, requiring frequent operations, which is not friendly to the manufacturer. Taking the above factors into consideration, the number of vacuum-assisted impregnations is set to 3 to 5 times, the vacuum level of each vacuum-assisted impregnation is -0.07 to -0.12 MPa, and the duration of each vacuum-assisted impregnation is 20 to 40 minutes. It will be understood that in other embodiments, the number of vacuum-assisted impregnations, the vacuum level, and the duration of each vacuum-assisted impregnation can be set according to actual needs, so that most of the sulfide solid electrolyte is loaded on the three-dimensional MXene material.

[0087] In this embodiment, in step S240, the vacuum drying temperature is 50 to 70°C (e.g., 60°C), the vacuum degree of the vacuum drying is -0.07 to -0.12 MPa (e.g., -0.1 MPa), and the vacuum drying time is 8 to 20 hours (e.g., 12 hours). A vacuum drying temperature of 50 to 70°C can maintain the structural stability of the sulfide solid electrolyte (or halide solid electrolyte) and the three-dimensional MXene material, thereby ensuring low lattice distortion of the sulfide solid electrolyte (or halide solid electrolyte) and low deformation rate of the three-dimensional MXene material, thereby preventing chemical reactions between the sulfide solid electrolyte (or halide solid electrolyte) and the three-dimensional MXene material and the solvent. On this basis, and taking into account the volatility of the solvent, the vacuum degree of the vacuum drying is set to -0.07 to -0.12 MPa and the vacuum drying time is set to 8 to 20 hours, which can reduce the residual solvent.

[0088] In this embodiment, a battery is also provided. The battery includes the composite solid electrolyte described above. In this embodiment, the composite solid electrolyte is used in the battery's separator. In other embodiments, the composite solid electrolyte can also be used in the battery's positive and negative electrodes.

[0089] In this embodiment, an electric device is also provided, which includes the above-mentioned battery. The above-mentioned electric device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, an energy storage device, an amusement ride, an elevator and a lifting device, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc.; the electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy or an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and an electric tool for railway use, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc.; the energy storage device can be an energy storage wall, a base station energy storage, a container energy storage, etc.; the amusement ride can be a carousel, a bungee jumping machine, etc. This embodiment does not impose any special restrictions on the above-mentioned electric devices.

[0090] Example 1

[0091] (1) Preparation of MXene

[0092] The raw materials for preparing Mxene were purchased Ti3AlC2MAX phase powder (D50 particle size less than or equal to 40 μm). In the process of preparing Mxene, the raw materials were added to a mixed solution of hydrofluoric acid (HF, concentration 40 wt%) and LiF (HF:LiF = 5:1 molar ratio) and stirred at 50 ° C for 24 hours to remove the Al layer to generate Ti3C2T x MXene; after stirring, the solution is centrifuged and washed until the pH is greater than 6, and the precipitate is taken out to obtain MXene.

[0093] (2) Preparation of three-dimensional MXene materials

[0094] (2.1) MXene was dispersed in deionized water (concentration 5 mg / mL) and ultrasonicated (power 300 W, 2 h) to obtain a MXene dispersion.

[0095] (2.2) The MXene dispersion was injected into a polyurethane template (pore size of 100 μm), and then frozen to obtain an initial three-dimensional MXene material supported in the three-dimensional porous template. The freezing temperature of the freezing treatment was -80°C, the cooling rate of the freezing treatment was 5°C / min, the freezing treatment time was 24 hours, and the vacuum degree of the freezing treatment was less than or equal to 10 Pa. Subsequently, the initial three-dimensional MXene material supported in the three-dimensional porous template was freeze-dried to obtain a three-dimensional MXene material supported in the three-dimensional porous template. The freeze-drying temperature was -80°C, and the freeze-drying time was 48 hours. Finally, the three-dimensional porous template and the three-dimensional MXene material were separated to obtain a three-dimensional MXene material.

[0096] (3) Preparation of composite solid electrolyte

[0097] (3.1) Provide purchased sulfide solid electrolyte. The sulfide solid electrolyte is Li6PS5Cl nanopowder with a D50 particle size of less than or equal to 50nm.

[0098] (3.2) Li6PS5Cl nanopowder was added to acetonitrile to obtain a suspension (concentration 200 mg / mL); a three-dimensional MXene material was immersed in the suspension and vacuum-assisted impregnation was performed (vacuum degree -0.1 MPa, 30 minutes), repeated three times to obtain a mixture of a solid electrolyte supported on the three-dimensional MXene; the mixture was vacuum-dried (vacuum degree -0.1 MPa, 60°C, 12 hours) to remove residual solvent, to obtain a composite solid electrolyte of Li6PS5Cl supported on the three-dimensional MXene material. The weight percentage of the Li6PS5Cl nanopowder was 97%, and the weight percentage of the three-dimensional MXene material was 3%.

[0099] Before immersing the three-dimensional MXene material in the suspension, the specific surface area and pore volume of the three-dimensional MXene material are analyzed using nitrogen adsorption-desorption isotherms to obtain the original pore volume. After obtaining the composite solid electrolyte, the specific surface area and pore volume of the composite solid electrolyte are analyzed again using nitrogen adsorption-desorption isotherms to obtain the pore volume after loading. The pore filling rate of the three-dimensional MXene material is then calculated. Wherein, pore filling rate (%) = (1-pore volume after loading / original pore volume) * 100%.

[0100] (4) Preparation of composite solid electrolyte membrane

[0101] (4.1) Raw material processing

[0102] The composite solid electrolyte is mixed with n-hexane (used as a liquid medium in the wet ball milling process; non-polar organic solvents such as heptane, toluene, and xylene can also be used) in a mass ratio of (1-1.5):(4.5-5), and high-energy ball milling is performed (400 rpm, 4 hours). Then, after vacuum drying for 24 hours, a nanopowder with a particle size D50 = 1-2 μm is obtained; finally, large particles (>10 μm) are removed through a 400-mesh sieve to obtain a processed raw material (powder).

[0103] (4.2) Dry film formation

[0104] First, the processed raw material (powder) is evenly spread (thickness approximately 500μm) in a stainless steel mold (Φ = 50mm, with a gold-plated anti-stick surface). A pre-pressing pressure of 50MPa is applied for 5 minutes to form a self-supporting green body (thickness ~200μm). The green body is then placed in a hot press and hot-pressed to form a composite solid electrolyte membrane. Hot-pressing parameters include: temperature of 200-250°C (must be lower than the decomposition temperature of Li6PS5Cl, 300°C); pressure of 500MPa (pressurization in three stages: 0→200MPa / 30 seconds, 200→400MPa / 30 seconds, and 400→500MPa / 10 seconds); and a holding time of 15 minutes. (Thickness control: pressure is adjusted in real time using a laser thickness gauge, resulting in a final film thickness of 25±2μm.) The atmosphere is protected by argon gas, with an oxygen content of <1ppm.

[0105] (4.3) Encapsulation protection

[0106] The composite solid electrolyte membrane is encapsulated in an aluminum-plastic composite film (nickel-plated inner layer), sealed with argon gas, and the oxygen content is <0.01ppm.

[0107] (5) Battery preparation

[0108] (5.1) Positive electrode preparation: Lithium iron phosphate material, conductive carbon black, and binder are mixed in a mass ratio of 8:1:1 and coated on aluminum foil. After drying at 80-100°C under vacuum conditions for 8-12 hours, an electrode sheet with a coating thickness of 150 μm is obtained.

[0109] (5.2) Assembly of lithium-based batteries: Cut the positive electrode into 10 mm diameter sheets, use Celgard 2500 as the separator, 1 mol / L LiPF6 ethylene carbonate (EC) and diethyl carbonate (DEC) solution (solvent volume ratio of 1:1) as the electrolyte, and a 10 mm diameter lithium metal sheet as the negative electrode. Assemble the mold battery. Cut the solid electrolyte membrane into 17.8 mm diameter discs and assemble them with the lithium sheet in an Ar-filled glove box to form a rechargeable and dischargeable battery.

[0110] (6) Performance testing

[0111] Electrical performance test: The battery is cycle tested (0.2C) using the Xinwei test system, with a voltage range of 2.5 to 4.1V. The specific process is as follows:

[0112] The battery was charged to 4.1V at 0.2C in a 25°C constant temperature box, and then maintained at 4.1V constant voltage charging until the current dropped to 0.05C (the first charge capacity can be obtained through this step); after standing for 30 minutes, it was discharged to 2.5V at 0.2C constant current (the first discharge capacity can be obtained through this step). The above steps were repeated 100 times. Among them, the first coulombic efficiency = first discharge capacity / first charge capacity × 100%; the capacity retention rate after 100 cycles = (100th discharge capacity / first discharge capacity) × 100%; the first discharge specific capacity = first discharge capacity / mass of positive electrode active material; the specific capacity after 100 cycles = 100th discharge capacity / mass of positive electrode active material.

[0113] Ionic conductivity test: Through EIS test (frequency 0.1 Hz-1 MHz, amplitude 10 mV), calculate σ = L / (R×A), where L is the thickness of the composite solid electrolyte membrane, R is the resistance value of the composite solid electrolyte membrane, and A is the electrode area (the negative electrode area is the same as the positive electrode area).

[0114] Mechanical strength test: The elastic modulus of the composite solid electrolyte membrane was tested using a nanoindenter (load 50 mN, pressure holding 10 s).

[0115] Air stability: The composite solid electrolyte membrane was exposed to air with a humidity of 30%, and the H2S release and ionic conductivity decay rate were recorded.

[0116] The calculation formula of ionic conductivity attenuation rate (α) is:

[0117]

[0118] σ0 is the initial ionic conductivity (unit: S / cm), which is obtained by EIS measurement; σ is the ionic conductivity after exposure to air for 24 h, which is also obtained by EIS measurement.

[0119] Example 2

[0120] In the preparation of the composite solid electrolyte in (3), the mass percentage of the Li6PS5Cl nanopowder is 95%, and the mass percentage of the three-dimensional MXene material is 5%. Except for the mass percentage of the Li6PS5Cl nanopowder and the three-dimensional MXene material, all other parts are the same as those in Example 1.

[0121] Example 3

[0122] In the preparation of the composite solid electrolyte in (3), the mass percentage of the Li6PS5Cl nanopowder is 90%, and the mass percentage of the three-dimensional MXene material is 10%. Except for the mass percentage of the Li6PS5Cl nanopowder and the three-dimensional MXene material, all other parts are the same as those in Example 1.

[0123] Example 4

[0124] In the preparation of the composite solid electrolyte in (3), the mass percentage of the Li6PS5Cl nanopowder is 85%, and the mass percentage of the three-dimensional MXene material is 15%. Except for the mass percentage of the Li6PS5Cl nanopowder and the three-dimensional MXene material, all other parts are the same as those in Example 1.

[0125] Example 5

[0126] In the preparation of the composite solid electrolyte in (3), the mass percentage of the Li6PS5Cl nanopowder is 80%, and the mass percentage of the three-dimensional MXene material is 20%. Except for the mass percentage of the Li6PS5Cl nanopowder and the three-dimensional MXene material, all other parts are the same as those in Example 1.

[0127] Example 6

[0128] In the preparation of the composite solid electrolyte in (3), the mass percentage of the Li6PS5Cl nanopowder is 75%, and the mass percentage of the three-dimensional MXene material is 25%. Except for the mass percentage of the Li6PS5Cl nanopowder and the three-dimensional MXene material, all other parts are the same as those in Example 1.

[0129] Comparative Example 1

[0130] Omit step “(2) preparing a three-dimensional MXene material”, and then in step “(3) preparing a composite solid electrolyte”, use the MXene prepared in step (1) to replace the three-dimensional MXene material. Other parts are the same as in Example 3.

[0131] Comparative Example 2

[0132] Steps (1) to (3) are omitted, and in step (4), a sulfide solid electrolyte is used instead of a composite solid electrolyte. Other parts are the same as those in Example 3.

[0133] Table 1 Pore filling rate test results

[0134]

[0135]

[0136] According to Table 1 above, when the composite solid electrolyte includes 3-25 wt% of the three-dimensional Mxene material, the pore filling rate of the three-dimensional Mxene material is very high (greater than 80%), which indicates that in the above composite solid electrolyte, at least part of the solid electrolyte is filled in the pores of the three-dimensional Mxene material.

[0137] When the conditions of the preparation method are the same (for example, the number of vacuum-assisted impregnations is the same, and the time of each vacuum-assisted impregnation is the same), when the composite solid electrolyte includes 10 wt% of the three-dimensional MXene material, the pore filling rate of the three-dimensional MXene material is the highest; when the mass percentage of the three-dimensional MXene material gradually decreases, the pore filling rate of the three-dimensional MXene material gradually decreases, which may be because the solid electrolyte with a larger mass blocks the pores of the three-dimensional MXene material from the beginning, resulting in the solid electrolyte being unable to enter the pores of the three-dimensional MXene material in the subsequent process; when the mass percentage of the three-dimensional MXene material gradually increases, the pore filling rate of the three-dimensional MXene material gradually decreases, which may be because the volume of the solid electrolyte with a smaller mass is smaller than the volume of the pores of the three-dimensional MXene material.

[0138] Table 2 Electrical performance test results

[0139]

[0140] According to Table 2 above, the electrical properties of Comparative Example 1 are better than those of Comparative Example 2, which indicates that when the solid electrolyte includes 10 wt% of the two-dimensional Mxene material, the electrical properties can be improved, but the improvement is relatively small; and the electrical properties of Example 3 are significantly better than those of Comparative Example 1, which indicates that when the solid electrolyte includes 10 wt% of the three-dimensional Mxene material, the electrical properties can be significantly improved, and the improvement of the electrical properties by the three-dimensional Mxene material is better than the improvement of the electrical properties by the two-dimensional Mxene material.

[0141] When the solid electrolyte includes 3-25 wt % of the three-dimensional Mxene material, the electrical properties of the solid electrolyte are better than those of Comparative Example 2.

[0142] When the solid electrolyte includes 5-20 wt% of the three-dimensional MXene material, the electrical properties of the solid electrolyte are better than those of Comparative Example 1. However, when the solid electrolyte includes less than 5 wt% (e.g., 3 wt% in Example 1) or more than 20 wt% (e.g., 25 wt% in Example 6) of the three-dimensional MXene material, the electrical properties of the solid electrolyte are worse than those of Comparative Example 1, which is consistent with the percolation theory threshold.

[0143] Table 3 Results of ionic conductivity, mechanical strength and air stability

[0144]

[0145] The H2S release test is as follows: the sample (composite solid electrolyte membrane) is exposed to a flowing gas with a constant relative humidity and flow rate, and a pump-suction gas sensor is used for detection. The value on the pump-suction gas sensor is recorded after 24 hours, which is the H2S release amount (ppm / 24h). Specifically, it can be used Figure 4 The test was performed using the apparatus shown in the figure. The apparatus, connected by pipes, includes a nitrogen cylinder (Nitrogen) for releasing nitrogen, a flowmeter, a humidifier, a thermo-hygrometer, a pump-type gas sensor (H2S sensor), and a container containing the sample (sample). The flowmeter regulates the nitrogen flow rate, while the thermo-hygrometer controls the temperature and humidity, ensuring that the flowing gas with a constant relative humidity and flow rate is transported through the pipe to the container containing the sample. The pump-type gas sensor then records the cumulative amount of H2S produced over a 24-hour period, which is the H2S release amount (ppm / 24h).

[0146] According to Table 3 above, the ionic conductivity, mechanical strength and air stability of Comparative Example 1 are all better than those of Comparative Example 2, which indicates that when the solid electrolyte includes 10 wt% of the two-dimensional Mxene material, the electrical properties can be improved; and the ionic conductivity, mechanical strength and air stability of Example 3 are significantly better than those of Comparative Example 1, which indicates that when the solid electrolyte includes 10 wt% of the three-dimensional Mxene material, the ionic conductivity, mechanical strength and air stability can be significantly improved, and the improvement of the ionic conductivity, mechanical strength and air stability by the three-dimensional Mxene material is better than that by the two-dimensional Mxene material.

[0147] When the solid electrolyte includes 3-25 wt % of the three-dimensional Mxene material, the ionic conductivity, mechanical strength and air stability of the solid electrolyte are better than those of Comparative Example 2.

[0148] When the solid electrolyte includes 5-20 wt% of the three-dimensional MXene material, the ionic conductivity, mechanical strength, and air stability of the solid electrolyte are all better than those of Comparative Example 1. However, when the solid electrolyte includes less than 5 wt% (e.g., 3 wt% in Example 1) or greater than 20 wt% (e.g., 25 wt% in Example 6) of the three-dimensional MXene material, the ionic conductivity, mechanical strength, and air stability of the solid electrolyte are all worse than those of Comparative Example 1, which is consistent with the percolation theory threshold.

[0149] Example 7

[0150] In step (3.1), a purchased halide solid electrolyte is provided. The halide solid electrolyte is a Li3YCl6 nanopowder with a D50 particle size of less than or equal to 50 nm. In the air stability test of step (6), the HCl release amount is recorded. All other parts are the same as in Example 1.

[0151] The HCl release test method is the same as the H2S release test method. The HCl release test device and the H2S release test device are identical except for the pump-aspirated gas sensor. The pump-aspirated gas sensor in the HCl release test device is an HCl sensor.

[0152] Example 8

[0153] In step (3.1), a purchased halide solid electrolyte is provided. The halide solid electrolyte is a Li3YCl6 nanopowder with a D50 particle size of less than or equal to 50 nm. In the air stability test of step (6), the HCl release amount is recorded. All other parts are the same as in Example 2.

[0154] Example 9

[0155] In step (3.1), a purchased halide solid electrolyte is provided. The halide solid electrolyte is a Li3YCl6 nanopowder with a D50 particle size of less than or equal to 50 nm. In the air stability test of step (6), the HCl release amount is recorded. All other parts are the same as in Example 3.

[0156] Example 10

[0157] In step (3.1), a purchased halide solid electrolyte is provided. The halide solid electrolyte is a Li3YCl6 nanopowder with a D50 particle size of less than or equal to 50 nm. In the air stability test of step (6), the HCl release amount is recorded. All other parts are the same as in Example 4.

[0158] Example 11

[0159] In step (3.1), a purchased halide solid electrolyte is provided. The halide solid electrolyte is a Li3YCl6 nanopowder with a D50 particle size of less than or equal to 50 nm. In the air stability test of step (6), the HCl release amount is recorded. All other parts are the same as in Example 5.

[0160] Example 12

[0161] In step (3.1), a purchased halide solid electrolyte is provided. The halide solid electrolyte is a Li3YCl6 nanopowder with a D50 particle size of less than or equal to 50 nm. In the air stability test of step (6), the HCl release amount is recorded. All other parts are the same as in Example 6.

[0162] Comparative Example 3

[0163] Omit step “(2) preparing a three-dimensional MXene material”, and then in step “(3) preparing a composite solid electrolyte”, use the MXene prepared in step (1) to replace the three-dimensional MXene material. Other parts are the same as Example 9.

[0164] Comparative Example 4

[0165] Steps (1) to (3) are omitted, and in step (4), a sulfide solid electrolyte is used instead of a composite solid electrolyte. Other parts are the same as those in Example 9.

[0166] Table 4 Pore filling rate test results

[0167]

[0168]

[0169] According to Table 4 above, when the composite solid electrolyte includes 3-25 wt% of the three-dimensional Mxene material, the pore filling rate of the three-dimensional Mxene material is very high (greater than 80%), which indicates that in the above composite solid electrolyte, at least part of the solid electrolyte is filled in the pores of the three-dimensional Mxene material.

[0170] When the conditions of the preparation method are the same (for example, the number of vacuum-assisted impregnations is the same, and the time of each vacuum-assisted impregnation is the same), when the composite solid electrolyte includes 10 wt% of the three-dimensional MXene material, the pore filling rate of the three-dimensional MXene material is the highest; when the mass percentage of the three-dimensional MXene material gradually decreases, the pore filling rate of the three-dimensional MXene material gradually decreases, which may be because the solid electrolyte with a larger mass blocks the pores of the three-dimensional MXene material from the beginning, resulting in the solid electrolyte being unable to enter the pores of the three-dimensional MXene material in the subsequent process; when the mass percentage of the three-dimensional MXene material gradually increases, the pore filling rate of the three-dimensional MXene material gradually decreases, which may be because the volume of the solid electrolyte with a smaller mass is smaller than the volume of the pores of the three-dimensional MXene material.

[0171] Table 5 Electrical performance test results

[0172]

[0173]

[0174] According to Table 5 above, the electrical properties of Comparative Example 3 are better than those of Comparative Example 4, which indicates that when the solid electrolyte includes 10 wt% of the two-dimensional Mxene material, the electrical properties can be improved, but the improvement is relatively small; and the electrical properties of Example 9 are significantly better than those of Comparative Example 3, which indicates that when the solid electrolyte includes 10 wt% of the three-dimensional Mxene material, the electrical properties can be significantly improved, and the improvement of the electrical properties by the three-dimensional Mxene material is better than the improvement of the electrical properties by the two-dimensional Mxene material.

[0175] When the solid electrolyte includes 3-25 wt % of the three-dimensional Mxene material, the electrical properties of the solid electrolyte are better than those of Comparative Example 4.

[0176] When the solid electrolyte includes 5-20 wt% of the three-dimensional MXene material, the electrical properties of the solid electrolyte are better than those of Comparative Example 3. However, when the solid electrolyte includes less than 5 wt% (e.g., 3 wt% in Example 7) or more than 20 wt% (e.g., 25 wt% in Example 12) of the three-dimensional MXene material, the electrical properties of the solid electrolyte are worse than those of Comparative Example 3, which is consistent with the percolation theory threshold.

[0177] Table 6 Ionic conductivity, mechanical strength and air stability results

[0178] Case Ionic conductivity (S / cm) Elastic modulus (GPa) HCl release (ppm / 24h) Example 7 1.5×10-3 0.8 120 Example 8 2.5×10-3 1.2 80 Example 9 20×10-3 2.0 50 Example 10 15×10-3 1.5 70 Example 11 2×10-3 1.1 90 Example 12 1.2×10-3 0.7 130 Comparative Example 3 2×10-3 1.0 100 Comparative Example 4 1×10-3 0.5 150

[0179] According to Table 6 above, the ionic conductivity, mechanical strength and air stability of Comparative Example 3 are all better than those of Comparative Example 4, which indicates that when the solid electrolyte includes 10 wt% of the two-dimensional Mxene material, the electrical properties can be improved; and the ionic conductivity, mechanical strength and air stability of Example 9 are significantly better than those of Comparative Example 3, which indicates that when the solid electrolyte includes 10 wt% of the three-dimensional Mxene material, the ionic conductivity, mechanical strength and air stability can be significantly improved, and the improvement of the ionic conductivity, mechanical strength and air stability by the three-dimensional Mxene material is better than that by the two-dimensional Mxene material.

[0180] When the solid electrolyte includes 3-25 wt % of the three-dimensional Mxene material, the ionic conductivity, mechanical strength and air stability of the solid electrolyte are better than those of Comparative Example 4.

[0181] When the solid electrolyte includes 5-20 wt% of the three-dimensional MXene material, the ionic conductivity, mechanical strength, and air stability of the solid electrolyte are all better than those of Comparative Example 3. However, when the solid electrolyte includes less than 5 wt% (e.g., 3 wt% in Example 7) or greater than 20 wt% (e.g., 25 wt% in Example 12) of the three-dimensional MXene material, the ionic conductivity, mechanical strength, and air stability of the solid electrolyte are all worse than those of Comparative Example 3, which is consistent with the percolation theory threshold.

[0182] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0183] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A composite solid electrolyte, characterized in that It includes a three-dimensional MXene material and a solid electrolyte, wherein the three-dimensional MXene material has a porous structure, the solid electrolyte includes a sulfide solid electrolyte or a halide solid electrolyte, and the solid electrolyte is loaded on the three-dimensional MXene material.

2. The composite solid electrolyte according to claim 1, characterized in that The general chemical formula of the three-dimensional MXene material is M n+1 X n Tx, n is a natural number of 1-3, M is a transition metal element, X is a carbon or nitrogen element, Tx is a surface functional group, and Tx includes a -F surface functional group; and / or The mass percentage of the solid electrolyte is 80-95%, and the mass percentage of the three-dimensional MXene material is 5-20%; and / or The pore filling rate of the three-dimensional MXene material is greater than or equal to 80%; and / or A chemical bond is formed between the three-dimensional MXene material and the solid electrolyte; and / or The pore size of the three-dimensional MXene material is 50-200 nm, and the particle size of the solid electrolyte is 30-150 nm.

3. The composite solid electrolyte according to claim 1, characterized in that The three-dimensional MXene material is Ti3C2Tx or Mo2CTx, and the sulfide solid electrolyte includes Li6PS5Cl, Li7P3S 11 or Li 10 GeP2S 12 .

4. The composite solid electrolyte according to claim 1, characterized in that The particle size of the three-dimensional MXene material is in the micron order, and the particle size of the solid electrolyte is in the nanometer order.

5. A method for preparing a composite solid electrolyte according to any one of claims 1 to 4, characterized in that: The steps include: Provide solid-state electrolytes and three-dimensional MXene materials; adding a solid electrolyte to a solvent to obtain a suspension; Immersing the three-dimensional MXene material in the suspension and performing vacuum-assisted impregnation to obtain a mixed solution in which the solid electrolyte is supported on the three-dimensional MXene; and The mixed solution is vacuum dried to obtain a composite solid electrolyte.

6. The method for preparing a composite solid electrolyte according to claim 5, characterized in that: The solvent is acetonitrile, and in the suspension, the concentration of the solid electrolyte is 150-250 mg / mL; and / or The number of vacuum-assisted impregnation is 3 to 5 times, the vacuum degree of vacuum-assisted impregnation is -0.07 to -0.12 MPa, and the time of vacuum-assisted impregnation is 20 to 30 minutes; and / or The temperature of the vacuum drying is 50 to 70° C., the vacuum degree of the vacuum drying is -0.07 to -0.12 MPa, and the time of the vacuum drying is 8 to 20 hours.

7. The method for preparing a composite solid electrolyte according to claim 5, characterized in that: The preparation method of the three-dimensional Mxene material comprises the following steps: MXene was added to deionized water and ultrasonically treated to obtain a MXene dispersion; The MXene dispersion is injected into the three-dimensional porous template and subjected to freezing treatment to obtain the initial three-dimensional MXene material supported in the three-dimensional porous template; The initial three-dimensional Mxene material supported in the three-dimensional porous template is freeze-dried to obtain the three-dimensional Mxene material supported in the three-dimensional porous template; as well as The three-dimensional porous template and the three-dimensional Mxene material are separated to obtain the three-dimensional Mxene material.

8. The method for preparing a composite solid electrolyte according to claim 7, wherein: The concentration of the MXene dispersion is 2 to 10 mg / mL; and / or The power of the ultrasonic treatment is 200 to 400 W, and the time of the ultrasonic treatment is 1 to 3 hours; and / or The pore size of the three-dimensional porous template is 50 to 200 μm; and / or The three-dimensional porous template is a polyurethane template; and / or The freezing temperature of the freezing treatment is -60°C to -100°C, the cooling rate of the freezing treatment is 2 to 10°C / min, the freezing treatment time is 12 to 36 hours, and the vacuum degree of the freezing treatment is less than or equal to 10 Pa; and / or The freeze-drying temperature is -60°C to -100°C, and the freeze-drying time is 36 to 60 hours.

9. A battery, characterized in that: The method comprises the composite solid electrolyte according to any one of claims 1 to 4.

10. An electrical device, characterized in that: Comprising the battery of claim 9.

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