Solid electrolyte composite material and preparation method thereof, diaphragm and battery

Abstract

The invention provides a solid-state electrolyte composite material and a preparation method thereof, a diaphragm and a battery, the solid-state electrolyte composite material comprises a solid-state electrolyte and a particle layer existing on the surface of the solid-state electrolyte, the particle layer comprises porous nanoparticles, the ratio of the particle size of the porous nanoparticles to the particle size of the inorganic solid electrolyte is 0.01-1. According to the invention, the hydrophilicity of the solid electrolyte composite material can be reduced, and the electrochemical performance such as ionic conductivity of the solid electrolyte composite material can be improved.

Description

Technical Field

[0001] The present invention relates to the field of electrolyte materials, and in particular to a solid electrolyte composite material and a preparation method thereof, a diaphragm and a battery. Background Art

[0002] Inorganic solid electrolyte materials have strong ion conductivity and are often used in solid-state batteries. However, inorganic solid electrolyte materials have high water affinity and are prone to absorb moisture during storage and application (for example, they absorb moisture when stored in the air), and the absorbed moisture will have a serious impact on the electrochemical properties of the inorganic solid electrolyte materials, thereby affecting the performance of the battery. Currently, the main method for low-moisture modification of inorganic solid electrolyte materials is to coat the surface of the inorganic solid electrolyte materials with hydrophobic materials, such as aluminum oxide, fluoropolymers, silane coupling agents, polydopamine materials, etc., in order to improve the surface hydrophobicity of the inorganic solid electrolyte materials, thereby achieving the low-moisture performance of the inorganic solid electrolyte materials. However, coating the surface of the inorganic solid electrolyte material with a hydrophobic material will form a dense coating layer with poor ionic conductivity on the surface of the electrolyte material, thereby affecting the electrochemical performance of the battery.

[0003] Therefore, how to reduce the water absorption capacity of inorganic solid electrolyte materials while maintaining their good electrochemical properties such as ionic conductivity is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0004] The present invention provides a solid electrolyte composite material and a preparation method thereof, a diaphragm and a battery, which can reduce the water absorption capacity of inorganic solid electrolyte materials while maintaining their good electrochemical properties such as ionic conductivity, effectively overcoming the defects of the existing technology.

[0005] In one aspect of the present invention, a solid electrolyte composite material is provided, comprising an inorganic solid electrolyte and a particle layer present on the surface of the inorganic solid electrolyte, wherein the particle layer comprises porous nanoparticles, and the ratio of the particle size of the porous nanoparticles to the particle size of the inorganic solid electrolyte is 0.01 to 1.

[0006] According to one embodiment of the present invention, the ratio of the particle size of the porous nanoparticles to the particle size of the inorganic solid electrolyte is 0.05 to 0.5.

[0007] According to one embodiment of the present invention, the average pore size of the porous nanoparticles is 0.5 nm to 5 nm; and / or the particle size distribution of the porous nanoparticles satisfies 0.5 ≤ (D90-D10) / D50 ≤ 1.8, preferably 0.8 ≤ (D90-D10) / D50 ≤ 1.5; and / or the particle size of the porous nanoparticles is 20 to 1500 nm; and / or the specific surface area of ​​the porous nanoparticles is 150 to 2000 g / m 2 , preferably 1000~1800g / m 2 .

[0008] According to one embodiment of the present invention, the density of the granular layer is 0.1 to 2.0 g / cm 3 , preferably 0.1 to 0.3 g / cm 3 ; and / or, the thickness of the particle layer is 50 to 5000 nm, preferably 50 to 1200 nm.

[0009] According to one embodiment of the present invention, the solid electrolyte composite material includes silicon-oxygen bonds connecting the porous nanoparticles and the surface of the inorganic solid electrolyte.

[0010] According to one embodiment of the present invention, the solid electrolyte composite material further includes a first group; preferably, the first group includes one or more of vinyl, epoxy, and amino groups; preferably, the molar content of the first group in the solid electrolyte composite material is 0.1% to 5%.

[0011] According to one embodiment of the present invention, the specific surface area of ​​the solid electrolyte composite material is 50 to 500 g / m 2 .

[0012] Another aspect of the present invention provides a method for preparing the above-mentioned solid electrolyte composite material, comprising the following steps: mixing an inorganic solid electrolyte, a first solvent and porous nanoparticles to obtain a second mixed system; and then subjecting the second mixed system to a first drying treatment to obtain the solid electrolyte composite material.

[0013] According to one embodiment of the present invention, the mass ratio of the porous nanoparticles to the inorganic solid electrolyte is 0.1% to 40%.

[0014] According to one embodiment of the present invention, the process of mixing the inorganic solid electrolyte, the first solvent and the porous nanoparticles comprises: mixing a first mixed system comprising the inorganic solid electrolyte and the first solvent with the porous nanoparticles, stirring for 4 to 12 hours to obtain the second mixed system; preferably, the first mixed system also includes a silane coupling agent; preferably, the first mixed system is acidic, and preferably the pH of the first mixed system is 4 to 5; preferably, the preparation process of the first mixed system comprises: mixing the inorganic solid electrolyte and the first solvent, then adding a silane coupling agent thereto, adjusting the pH to 4 to 5, and stirring for 1 hour to 7 hours to obtain the first mixed system; preferably, the silane coupling agent The mass ratio of the silane coupling agent to the inorganic solid electrolyte is 1% to 10%; preferably, the silane coupling agent includes diethylenetriaminopropyltrimethoxysilane, triethoxyvinylsilane, vinyltrimethoxysilane, aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-aminopropyl(diethoxy)methylsilane, 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane. One or more of silane.

[0015] According to one embodiment of the present invention, the first drying process includes: performing solid-liquid separation on the second mixed system, and then performing a first drying on the obtained solid product to obtain the solid electrolyte composite material; preferably, the temperature of the first drying is 60-100°C.

[0016] Another aspect of the present invention provides a diaphragm, comprising a base membrane and a solid electrolyte layer present on at least one side surface of the base membrane, wherein the solid electrolyte layer comprises the above-mentioned solid electrolyte composite material or a solid electrolyte composite material prepared according to the preparation method of the above-mentioned solid electrolyte composite material.

[0017] According to one embodiment of the present invention, the moisture value of the separator is less than or equal to 1500 ppm.

[0018] Another aspect of the present invention provides a battery comprising the above separator.

[0019] According to one embodiment of the present invention, the battery is a semi-solid-state battery or an all-solid-state battery.

[0020] The solid electrolyte composite material provided by the present invention, as well as its preparation method and application, has a particle layer on the surface of the inorganic solid electrolyte, and the ratio of the particle size of the porous nanoparticles in the particle layer to the particle size of the inorganic solid electrolyte is 0.01 to 1. In such a solid electrolyte composite material system, the water absorption capacity of the solid electrolyte material can be reduced, thereby reducing the moisture content of the solid electrolyte material and ensuring its electrochemical performance. At the same time, the pore structure of the particle layer is conducive to ion transport, which can take into account the improvement of properties such as the ionic conductivity of the solid electrolyte composite material, thereby improving battery performance, specifically taking into account the improvement of the battery's first-cycle coulomb efficiency, rate performance, and cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a solid electrolyte composite material according to one embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0023] The embodiment of the present invention provides a solid electrolyte composite material, such as Figure 1 As shown, the solid electrolyte composite material includes an inorganic solid electrolyte (core layer), a particle layer (shell layer) present on the surface of the inorganic solid electrolyte, the particle layer includes porous nanoparticles, and the ratio of the particle size D1 of the porous nanoparticles to the particle size D2 of the inorganic solid electrolyte is 0.01 to 1 (i.e., 0.01≤D1 / D2≤1).

[0024] According to the inventor's research, by forming a particle layer including porous nanoparticles on the surface of the inorganic solid electrolyte, a coating structure with the inorganic solid electrolyte as the core and the particle layer of porous nanoparticles as the shell is formed, and the ratio of the particle size D1 of the porous nanoparticles to the particle size D2 of the inorganic solid electrolyte is controlled within the range of 0.01 to 1. In such a solid electrolyte composite material system, the presence of porous nanoparticles in the particle layer is conducive to the formation of a relatively tortuous nanoporous structure in the particle layer. Such a particle layer structure is difficult to be penetrated by moisture in the environment and can serve as a protective layer to protect the solid electrolyte, avoiding direct contact between the solid electrolyte and moisture in the environment such as air, thereby reducing the solid electrolyte. The hydrophilicity of the solid electrolyte composite material is improved, that is, the water absorption capacity of the solid electrolyte composite material is reduced, and its moisture content is reduced to achieve the purpose of low-moisture modification of the solid electrolyte material. At the same time, maintaining the uniformity of the coating of the particle layer on the solid electrolyte is also a factor to ensure the protective effect of the particle layer on the solid electrolyte and reduce the water absorption capacity of the solid electrolyte; at the same time, the particle layer has a porous structure, and active ions such as lithium ions can be effectively transmitted through the porous structure, so that the solid electrolyte composite material has good ionic conductivity, ensuring its electrochemical performance, thereby improving battery performance, specifically taking into account improving the first-week coulomb efficiency, rate performance and high-temperature cycle performance of the battery.

[0025] Therefore, the embodiment of the present invention uses porous nanoparticles to perform surface coating modification on the inorganic solid electrolyte, forms the above-mentioned particle layer on the surface of the solid electrolyte, and controls the ratio of the particle size D1 of the porous nanoparticles to the particle size D2 of the inorganic solid electrolyte within the range of 0.01 to 1, which can reduce the contact area between the solid electrolyte and water, thereby reducing the surface hydrophilicity of the solid electrolyte composite material and solving the problem of high moisture content of the solid electrolyte material; at the same time, the porous nanoparticles in the particle layer form a rich nanopore structure, which can provide a transmission channel for active ions such as lithium ions, so that the solid electrolyte composite material maintains good ion transmission performance during the application process, thereby achieving both reducing the moisture content of the solid electrolyte composite material and improving the electrochemical properties such as ionic conductivity of the solid electrolyte composite material.

[0026] In addition, porous nanoparticles are used to coat and modify the solid electrolyte. Porous nanoparticles have the advantage of self-forming pores, which is conducive to the formation of a rich and uniform nanopore structure in the particle layer, reducing the moisture content of the solid electrolyte composite material and improving the electrochemical properties of the solid electrolyte composite material, such as ionic conductivity.

[0027] Specifically, if Figure 1As shown, the inorganic solid electrolyte is granular, and the particle layer on its surface is a shell layer (or coating layer) formed by the accumulation of porous nanoparticles on the surface of the solid electrolyte particles. In general, these porous nanoparticles are substantially evenly distributed on the surface of the inorganic solid electrolyte particles (i.e., the surface of the solid electrolyte particles is substantially completely covered by the particle layer), and the particle layer formed has a pore structure defined by the gaps between the porous nanoparticles. At the same time, the porous nanoparticles also have a nanopore structure, and the gaps (gaps) between the porous nanoparticles and the porous structure of the porous nanoparticles themselves jointly form the pore structure of the particle layer, while achieving water barrier while maintaining the passage of active ions such as lithium ions, thereby achieving both reducing the hydrophilicity of the solid electrolyte composite material and improving the electrochemical properties such as the ionic conductivity of the solid electrolyte composite material. Among them, the porous nanomaterial can specifically be bonded to the surface of the solid electrolyte.

[0028] For example, the ratio of the particle size D1 of the porous nanoparticles to the particle size D2 of the inorganic solid electrolyte may be 0.01, 0.05, 0.1, 0.3, 0.5, 0.7, 1, or a range consisting of any two thereof.

[0029] In some preferred embodiments, the ratio of the particle size D1 of the porous nanoparticles to the particle size D2 of the inorganic solid electrolyte is 0.05 to 0.5, which is conducive to further balancing the reduction of the hydrophilicity of the solid electrolyte composite material and the improvement of the electrochemical properties of the solid electrolyte composite material, such as ionic conductivity.

[0030] In the embodiments of the present invention, the particle size D1 of the porous nanoparticles and the particle size D2 of the inorganic solid electrolyte are both average particle sizes. The particle size D1 of the porous nanoparticles and the particle size D2 of the inorganic solid electrolyte can be measured by conventional methods in the art, such as statistically obtained by electron microscopy. For example, the particle size D1 of the porous nanoparticles and the particle size D2 of the inorganic solid electrolyte can be characterized and statistically calculated by transmission electron microscopy (TEM). In specific implementations, the testing method can be characterized according to the method specified in GB / T 18907-2013 "Microbeam Analysis Electron Microscopy - Selected Area Electron Diffraction Analysis Method for Transmission Electron Microscopy".

[0031] During the test, at least 20 solid electrolyte composite material particles can be randomly selected, and the diameter of the inorganic solid electrolyte and the diameter of the porous nanoparticles can be tested by TEM (at least the diameters of 20 porous nanoparticles are measured), and then the average value of the diameter of the porous nanoparticles (that is, the particle diameter of the porous nanoparticles (that is, the particle size D1)) and the average value of the diameter of the inorganic solid electrolyte (that is, the particle diameter of the inorganic solid electrolyte (that is, the particle size D2)) are obtained by statistical calculation (such as Image J software analysis and calculation), and the ratio of the two is calculated to obtain the ratio of the particle size D1 of the porous nanoparticles to the particle size D2 of the inorganic solid electrolyte.

[0032] Generally speaking, in a solid electrolyte composite material, the particle size of the inorganic solid electrolyte can be nanometer-scale (ie, it is a solid electrolyte nanoparticle) or micrometer-scale (ie, it is a solid electrolyte microparticle).

[0033] In some embodiments, the particle size D2 of the inorganic solid electrolyte can be 500 to 2500 nm, for example, 500 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, 2000 nm, 2500 nm, or a range consisting of any two thereof.

[0034] In some embodiments, the particle size D1 of the porous nanoparticles can be 20 to 1500 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1300 nm, 1500 nm or a range consisting of any two thereof.

[0035] In some embodiments, the particle size distribution D (D = (D90-D10) / D50) of the porous nanoparticles satisfies 0.5≤(D90-D10) / D50≤1.8, and (D90-D10) / D50 is, for example, 0.5, 0.8, 1, 1.3, 1.5, 1.8 or a range consisting of any two of them, preferably 0.8≤(D90-D10) / D50≤1.5, which is beneficial to further balance the reduction of the moisture content of the solid electrolyte composite material and the improvement of its electrochemical properties such as ionic conductivity. The reason for this is that the particle size distribution of the porous nanoparticles is within the above range, which is beneficial to the formation of a more suitable thickness and porous structure of the particle layer, while inhibiting moisture from passing through the particle layer, and is more conducive to the passage of active ions such as lithium ions.

[0036] Among them, D10 represents the particle size when the volume accumulation reaches 10% from the small particle size side in the particle size distribution of porous nanoparticles, D50 represents the particle size when the volume accumulation reaches 50% from the small particle size side in the particle size distribution of porous nanoparticles, and D90 represents the particle size when the volume accumulation reaches 90% from the small particle size side in the particle size distribution of porous nanoparticles.

[0037] In the embodiment of the present invention, the particle size D10, D50 and D90 of the porous nanoparticles can be measured by conventional methods in the art, for example, by a laser particle size analyzer. Specifically, a laser scattering particle size analyzer (Malvern ZEN3690 particle size analyzer) can be used for characterization. The porous nanoparticles are dispersed in pure water, and the D50, D90 and D10 of the porous nanoparticles are measured. The D50, D90 and D10 of the porous nanoparticles in the solid electrolyte composite material can also be obtained by the following statistical method: the solid electrolyte composite material particles are cut by a focused ion beam (FIB) or the like to obtain a cross section of the solid electrolyte composite material particles (the cross section substantially passes through the center of the solid electrolyte composite material particles (i.e., the center of the sphere)), and then the porous nanoparticles in the solid electrolyte composite material are scanned by a scanning electron microscope (SEM), and a scanning area of ​​100 μm*100 μm of the cut solid electrolyte composite material powder is randomly selected, and the D50, D90 and D10 of the porous nanoparticles in the solid electrolyte composite material are obtained by statistical analysis and calculation of the scanning results (such as analysis and calculation using Image J software).

[0038] In some embodiments, the average pore size of the porous nanoparticles is 0.5 nm to 5 nm, for example, 0.5 nm, 0.6 nm, 0.8 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, or a range consisting of any two thereof. The average pore size of the porous nanoparticles is not less than 0.5 nm, which is more conducive to the passage of active ions such as lithium ions, further improving its electrochemical properties such as ionic conductivity. At the same time, the average pore size of the porous nanoparticles is not greater than 100 nm, which is conducive to further reducing the contact between the solid electrolyte and water. The average pore size of the porous nanoparticles is within the range of 0.5 nm to 5 nm, which is more conducive to forming a more suitable pore structure in the particle layer through the pores of the porous nanoparticles themselves and the pores between the porous nanoparticles in the particle layer, taking into account the improvement of the protective effect of the particle layer on the solid electrolyte and the transmission capacity of the particle layer for active ions, thereby further taking into account the reduction and improvement of its electrochemical properties such as ionic conductivity.

[0039] In the embodiments of the present invention, the average pore size of the porous nanoparticles can be measured by conventional methods in the art, for example, by mercury intrusion porosimetry and PMI testing. Specifically, the testing method can be performed in accordance with the method in GB / T 21650.1-2008 "Mercury Intrusion Porosimetry and Gas Adsorption Method for Determination of Pore Size Distribution and Porosity of Solid Materials - Part 1: Mercury Intrusion Porosimetry".

[0040] In some embodiments, the specific surface area of ​​the porous nanoparticles may be 150 to 2000 g / m 2 , for example 150g / m 2 , 200g / m 2 , 210g / m 2 , 300g / m 2 , 500g / m 2 , 700g / m 2 , 1000g / m 2 , 1200g / m 2 , 1300g / m 2 , 1400g / m 2 , 1500g / m 2 , 1600g / m 2 , 1700g / m 2 , 1800g / m 2 , 2000g / m 2 or the range of any two of them, preferably 1000 to 1800 g / m 2 The specific surface area of ​​the porous nanoparticles is within the above range, which is conducive to further taking into account the low hydrophilicity and high ionic conductivity of the solid electrolyte composite material.

[0041] In some embodiments, the density of the particle layer can be 0.1 to 2.0 g / cm 3 , for example 0.1 g / cm 3 , 0.11g / cm 3 , 0.12g / cm 3 , 0.14g / cm 3 , 0.15g / cm 3 , 0.16g / cm 3 , 0.17g / cm 3 , 0.18g / cm 3 , 0.19g / cm 3 , 0.2g / cm 3 , 0.21g / cm 3 , 0.24g / cm 3 , 0.26g / cm 3 , 0.3g / cm 3 , 0.32g / cm 3, 0.34g / cm 3 , 0.4g / cm 3 , 0.5g / cm 3 , 0.8g / cm 3 , 1g / cm 3 , 1.3g / cm 3 , 1.5g / cm 3 , 1.8g / cm 3 , 2g / cm 3 or the range of any two of them, preferably 0.1 to 0.3 g / cm 3 The density of the particle layer is within the above range, which is conducive to further taking into account the low hydrophilicity and high ionic conductivity of the solid electrolyte composite material. The reason for this is that density is the ratio of mass to volume. By synergistically regulating the mass and volume of the particle layer to meet the above density range, it is more conducive to the formation of a more suitable pore structure in the particle layer, while inhibiting water from passing through the particle layer, it is more conducive to the passage of lithium ions and other ions.

[0042] Specifically, the density of the particle layer is the ratio of the mass of the particle layer to the volume of the particle layer. The mass of the particle layer can be obtained by weighing, and the particle diameter of the solid electrolyte composite material and the diameter of the inorganic solid electrolyte particles (particle size D2) are measured by transmission electron microscopy (TEM) and converted into volume (according to the spherical volume formula (V = (4 / 3)πR 3 , R is the radius of the material particle) and the volume of the solid electrolyte composite material and the volume of the inorganic solid electrolyte are converted respectively), and then the volume of the particle layer is calculated (the volume of the particle layer = the volume of the solid electrolyte composite material - the volume of the inorganic solid electrolyte), and then the volume ratio of the particle layer κ (κ = the volume of the particle layer / the volume of the solid electrolyte composite material). The density of the particle layer ρ m It can be calculated by the following formula:

[0043]

[0044] Among them, M1 is the mass of the solid electrolyte composite material (i.e., the mass of the solid electrolyte after being coated by the particle layer); M0 is the mass of the inorganic solid electrolyte; ρ is the true density of the solid electrolyte composite material, which can be characterized by the test method specified in the national standard GB-T24203-2024 "Determination of volume density, true density, true porosity and apparent porosity of carbon materials". In the embodiment of the present invention, the helium method can be specifically selected for characterization.

[0045] In specific implementation, when testing the diameter of the solid electrolyte composite material, the diameter of the solid electrolyte composite material particles can be tested by TEM. Specifically, the diameters of at least 20 solid electrolyte composite material particles can be tested, and then the average value of the measured diameters of at least 30 solid electrolyte composite material particles is calculated, which is the particle diameter of the electrolyte material.

[0046] In some embodiments, the thickness of the particle layer can be 50 to 5000 nm, for example, 50 nm, 60 nm, 80 nm, 100 nm, 300 nm, 500 nm, 800 nm, 1000 nm, 1200 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, 4000 nm, 4500 nm, 5000 nm, or a range consisting of any two of these. In this way, the thickness of the particle layer is not less than 50 nm, which can better play a protective role and reduce the contact between the solid electrolyte and water, thereby further reducing the water absorption capacity and moisture content of the solid electrolyte composite material. At the same time, the thickness of the particle layer is not more than 5 μm, which is more conducive to the passage of active ions such as lithium ions through the particle layer, thereby further improving the electrochemical properties such as ionic conductivity of the solid electrolyte composite material.

[0047] In some preferred embodiments, the thickness of the particle layer may be 50 to 1200 nm, which is beneficial for further taking into account both reducing the water absorption capacity of the solid electrolyte composite material and improving the electrochemical properties of the solid electrolyte composite material, such as ionic conductivity.

[0048] In an embodiment of the present invention, when testing the thickness of the particle layer, the thickness of the particle layer can be tested by TEM. In specific implementation, the thickness of the particle layer of at least 20 solid electrolyte composite material particles can be tested, and then the average value of the at least 20 measured thickness values ​​is calculated, which is the thickness of the particle layer.

[0049] In general, the thickness of the particle layer is greater than or equal to the average particle size of the porous nanoparticles. Specifically, the porous nanoparticles in the particle layer can be arranged in a single layer, that is, the porous nanoparticles in the particle layer are basically not stacked in the direction from the center to the surface of the solid electrolyte composite material, but exist in the form of single particles (such as Figure 1 As shown), in this case, the thickness of the particle layer is substantially equal to the average particle size of the porous nanoparticles; alternatively, the porous nanoparticles in the particle layer may be arranged in multiple layers, that is, the porous nanoparticles in at least part of the particle layer are stacked in the direction from the center to the surface of the solid electrolyte composite material, and in this case, the thickness of the particle layer is greater than the average particle size of the porous nanoparticles.

[0050] Furthermore, the porous nanoparticles may include one or more of porous inorganic materials, porous organic materials, and porous organic-inorganic hybrid materials.

[0051] Exemplarily, the porous inorganic material may include a porous inorganic oxide material, which may include one or more of porous alumina, porous titania, and porous silica. The porous inorganic material may specifically include aerogel materials and / or non-aerogel materials. The aerogel material may include, for example, an inorganic oxide aerogel, which may include one or more of silica aerogel, alumina aerogel, and titania aerogel; the non-aerogel material may include, for example, one or more of porous nano-alumina, porous nano-titania, and porous nano-silica.

[0052] Illustratively, the porous organic material may include a porous covalent organic framework (COF) material, a porous polymer material, and / or a porous cyclodextrin material.

[0053] For example, the porous polymer material may include a porous cage-type polysilsesquioxane (POSS) material.

[0054] For example, the porous organic-inorganic hybrid material may include a porous metal-organic framework (MOF) material, and the porous metal-organic framework material, for example, includes 2-methylimidazole zinc salt (ZIF-8) and / or 2-methylimidazole cobalt salt (ZIF-67).

[0055] In some embodiments, the porous nanoparticles include one or more of a porous cage-type polysilsesquioxane (POSS) material, a porous metal organic framework (MOF) material, a porous covalent organic framework (COF) material, a porous cyclodextrin material, a porous nano-oxide material, and an aerogel material. Among them, the porous nano-oxide material may include one or more of porous nano-alumina, porous nano-titania, and porous nano-silica, the aerogel material may include an inorganic oxide aerogel, the inorganic oxide aerogel may include one or more of silica aerogel, alumina aerogel, and titania aerogel, and the porous metal organic framework material may include 2-methylimidazole zinc salt (ZIF-8) and / or 2-methylimidazole cobalt salt (ZIF-67).

[0056] By using at least one of the above-mentioned porous nanoparticle materials to coat and modify the solid electrolyte to form a particle layer, it is more conducive to the particle layer having a nanopore structure with appropriate tortuosity and richness, inhibiting the passage of water, and at the same time providing a physical channel for the transmission of active ions such as lithium ions, further reducing the water absorption of the solid electrolyte composite material and improving the electrochemical properties of the solid electrolyte composite material such as ionic conductivity.

[0057] In an embodiment of the present invention, the solid electrolyte composite material may further contain silicon-oxygen bonds (-Si-O-), which are generally connected between the porous nanoparticles and the inorganic solid electrolyte. That is, the solid electrolyte composite material may include silicon-oxygen bonds connecting the porous nanoparticles and the surface of the inorganic solid electrolyte. The presence of silicon-oxygen bonds is beneficial to increasing the adhesion between the particle layer and the solid electrolyte, further improving the structural stability and other properties of the solid electrolyte composite material.

[0058] In the embodiment of the present invention, the silicon-oxygen bonds in the solid electrolyte composite material can be tested by infrared spectroscopy (FTIR).

[0059] In addition, the solid electrolyte composite material may further contain a first group, which may specifically include one or more of vinyl, epoxy, and amino groups.

[0060] According to the inventors' research, the first group can act as an active group to participate in the electrochemical reaction of the battery during the preparation process or application process (the above-mentioned epoxy group and other groups can react with the active component functional groups in the electrolyte and other materials during the charge and discharge process of the battery), forming more stable chemical bonds and other groups, thereby further improving the battery performance. For example, when the solid electrolyte composite material is applied to a semi-solid battery, the vinyl, epoxy, and amino groups therein act as active reaction groups and can participate in the chemical reaction process of preparing the semi-solid battery, so that the diaphragm containing the above-mentioned solid electrolyte composite material and the electrode (such as the positive electrode and / or the negative electrode) are more tightly bonded, thereby helping to reduce the interfacial impedance between the diaphragm and the electrode and improve the electrochemical stability such as the cycle capacity retention rate of the battery.

[0061] Generally, the first group exists between the inorganic solid electrolyte and the particle layer, which makes the core-shell structure of the solid electrolyte composite material have a coupling structure and a tighter connection. The first group can be introduced by modifying the material with a silane coupling agent.

[0062] In some embodiments, the molar content of the first group in the solid electrolyte composite material can be 0.1% to 5%, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any two thereof, which is beneficial to further improve the electrochemical properties of the battery, such as the cycle capacity retention rate.

[0063] In addition, in some embodiments, the solid electrolyte composite material may further contain a second group, wherein the second group includes a hydrophobic group, which can further reduce the surface hydrophilicity of the solid electrolyte composite material, thereby reducing its water absorption capacity and moisture content.

[0064] Specifically, the number of carbon atoms in the second group (hydrophobic group) can be 1 to 20, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0065] Specifically, the second group (hydrophobic group) may include an alkyl group and / or a fluorine-containing group. The alkyl group may include an alkyl group having 1 to 20 carbon atoms. The alkyl group may be a straight-chain alkyl group or a branched alkyl group. The fluorine-containing group may be substituted on one carbon atom of the alkyl group, or on multiple carbon atoms of the alkyl group, the fluorine-containing group may be substituted with a fluorine-containing group. For example, the alkyl group may include at least one of a methyl group, an ethyl group, a propyl group, and a butyl group. The fluorine-containing group includes a fluorine atom or other substituent containing a fluorine atom. The second group may contain one or more fluorine-containing groups. One or more fluorine-containing groups may be substituted on one carbon atom. When multiple fluorine-containing groups are contained, the multiple fluorine-containing groups may be substituted on the same carbon atom or on different carbon atoms (i.e., multiple carbon atoms substituted with fluorine-containing groups are present in the second group).

[0066] In some embodiments, the second group (hydrophobic group) may include a fluoroalkyl group, specifically a fluoroalkyl group with 1 to 20 carbon atoms. The fluoroalkyl group may contain one fluorine atom (monofluoroalkyl group) or multiple fluorine atoms (polyfluoroalkyl group). The fluorine atom may be substituted on one carbon atom in the fluoroalkyl group, or multiple carbon atoms in the fluoroalkyl group may be substituted with fluorine atoms.

[0067] Specifically, the second group (such as a fluoroalkyl group) may include at least one methyl group substituted by a fluorine-containing group (such as a fluoromethyl group) and / or at least one methylene group substituted by a fluorine-containing group (such as a fluoromethylene group). In addition, the second group may also include or exclude a methyl group (-CH3) not substituted by a fluorine-containing group and / or a methylene group (-CH2-) not substituted by a fluorine-containing group.

[0068] Wherein, at least one hydrogen atom in the methylene group substituted by a fluorine-containing group is replaced by a fluorine-containing group, specifically one hydrogen atom is replaced by a fluorine-containing group, or two hydrogen atoms are replaced by a fluorine-containing group, or three hydrogen atoms are replaced by fluorine-containing groups. Taking a fluoromethane group as an example, at least one hydrogen atom in a fluoromethane group is replaced by a fluorine atom, specifically one hydrogen atom is replaced by a fluorine atom (a fluoromethane group is a monofluoromethane group (-CH2F)), or two hydrogen atoms are replaced by fluorine atoms (a fluoromethane group is a difluoromethane group (-CHF2)), or three hydrogen atoms are replaced by fluorine atoms (a fluoromethane group is a trifluoromethane group (-CF3)), and the second group can include one or more of a monofluoromethane group, a difluoromethane group, and a trifluoromethane group.

[0069] In addition, at least one hydrogen atom in the methylene group substituted with a fluorine-containing group is replaced by a fluorine-containing group, specifically one hydrogen atom is replaced by a fluorine-containing group, or both hydrogen atoms are replaced by fluorine-containing groups. Taking fluoromethylene as an example, at least one hydrogen atom in the fluoromethylene group is replaced by a fluorine atom, specifically one hydrogen atom is replaced by a fluorine atom (fluoromethylene is monofluoromethylene (-CHF-)), or both hydrogen atoms are replaced by fluorine atoms (fluoromethylene is difluoromethylene (-CF2-)), and the second group may include monofluoromethylene and / or difluoromethylene.

[0070] In some specific embodiments, the fluoroalkyl group may include one or more of a fluoromethyl group, a fluoroethyl group, a fluoropropyl group, and a fluorobutyl group. The fluoromethyl group includes, for example, one or more of a monofluoromethyl group (-CH2F), a difluoromethyl group (-CHF2), and a trifluoromethyl group (-CF3). The fluoroethyl group includes, for example, a monofluoroethyl group (-C2H4F) and / or a polyfluoroethyl group containing multiple fluorine atoms. The polyfluoroethyl group includes, for example, a difluoroethyl group. The difluoroethyl group includes, for example, 1,1-difluoroethane (CH3-CHF2). The fluoropropyl group includes, for example, a monofluoropropyl group and / or a polyfluoropropyl group containing multiple fluorine atoms. The polyfluoropropyl group includes, for example, a trifluoropropyl group. The trifluoropropyl group includes, for example, 1,1,1-trifluoropropyl (-CH2-CH2-CF3). These groups have good hydrophobicity and can reduce the adsorption of water on the surface of the solid electrolyte composite material, thereby further reducing the moisture content of the solid electrolyte composite material.

[0071] In some specific embodiments, the fluoroalkyl group includes, for example, one or more of a fluoromethane group (-CH2F), a difluoromethane group (-CHF2), a trifluoromethane group (-CF3), a monofluoroethane group (-C2H4F), a 1,1-difluoroethane group (CH3-CHF2), a 1,1,1-trifluoropropane group (-CH2-CH2-CF3), etc., which is beneficial to further reduce the moisture content of the solid electrolyte composite material.

[0072] Generally, the second group exists on the surface of the particle layer and in the gaps between the particles, and can be introduced through a silicon-oxygen bond (-Si-O-) formed by a reaction of a silane coupling agent or a reaction of an epoxy group with a siloxane compound.

[0073] In some embodiments, the molar content of the second group in the solid electrolyte composite material is 0.1% to 5%, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any two thereof, which is beneficial to further reduce the moisture content of the solid electrolyte composite material.

[0074] In an embodiment of the present invention, the molar content of the first group (functional group) or the second group (functional group) in the solid electrolyte composite material can be tested by infrared spectroscopy (FTIR). In specific implementation, the solid electrolyte composite material can be subjected to infrared spectroscopy to measure the infrared spectrum of the solid electrolyte composite material, where the molar content of the first group in the solid electrolyte composite material = the peak area of ​​the characteristic absorption peak of the first group / the sum of the peak areas of all characteristic absorption peaks in the infrared spectrum, and the molar content of the second group in the solid electrolyte composite material = the peak area of ​​the characteristic absorption peak of the second group / the sum of the peak areas of all characteristic absorption peaks in the infrared spectrum.

[0075] In some embodiments, the inorganic solid electrolyte may include one or more of LATP (lithium aluminum titanium phosphate) and its doped modified derivatives, LAGP (lithium aluminum germanium phosphate) and its doped modified derivatives, LLTO (lithium lanthanum titanium oxide) and its doped modified derivatives, LLZTO (lithium lanthanum zirconium tantalum oxide) and its doped modified derivatives, LLZO (lithium lanthanum zirconium oxide) and its doped modified derivatives.

[0076] Specifically, in the element-doped modified derivatives, the doping elements may include one or more of silicon, tantalum, bismuth, iron, yttrium, indium, lutetium, gallium, rubidium, chromium, iron, aluminum, cerium, strontium, germanium, zinc, magnesium, and tungsten.

[0077] In the embodiment of the present invention, the solid electrolyte composite material is in granular form, and its macroscopic appearance is powder. In some embodiments, the specific surface area of ​​the solid electrolyte composite material can be 50 to 500 g / m 2 , for example 50g / m 2 , 55g / m 2 , 70g / m 2 , 100g / m 2 , 120g / m 2 , 150g / m 2 , 200g / m 2 , 250g / m 2 , 300g / m 2 , 320g / m 2 , 350g / m 2 , 400g / m 2 , 450g / m 2 , 500g / m 2 or a range consisting of any two of them.

[0078] An embodiment of the present invention also provides a method for preparing the aforementioned solid electrolyte composite material, comprising the following steps: mixing an inorganic solid electrolyte, a first solvent, and porous nanoparticles to obtain a second mixed system; and then subjecting the second mixed system to a first drying process to obtain the solid electrolyte composite material. This preparation process involves modifying the inorganic solid electrolyte surface with porous nanoparticles to form a particle layer, thereby producing the aforementioned solid electrolyte composite material. While reducing the hydrophilicity of the resulting solid electrolyte composite material, the nanoporous structure of the particle layer provides channels for the transport of active ions such as lithium ions, thereby enhancing the ion transport capacity of the solid electrolyte composite material.

[0079] In some embodiments, the mass ratio of the porous nanoparticles to the inorganic solid electrolyte can be 0.1% to 40%, for example, 0.1%, 1%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any combination thereof. A suitable mass ratio is more conducive to the particle layer forming a suitable pore structure on the surface of the inorganic solid electrolyte, inhibiting water erosion of the solid electrolyte while facilitating the passage of active ions such as lithium ions.

[0080] In some embodiments, the process of mixing the inorganic solid electrolyte, the first solvent, and the porous nanoparticles may include: mixing a first mixed system including the inorganic solid electrolyte and the first solvent with the porous nanoparticles to obtain a second mixed system.

[0081] In some specific embodiments, the first mixed system may further include a silane coupling agent. The silane coupling agent can chemically connect the inorganic solid electrolyte and the porous nanoparticles by forming a silicon-oxygen bond, thereby forming a more compact porous nanoparticle coating layer structure (particle layer). At the same time, the hydrolysis process of the silane coupling agent can also introduce a first group, which is beneficial for further reducing the interfacial impedance between the separator and the electrode, thereby improving the performance of the battery.

[0082] In some embodiments, the preparation process of the first mixed system may include: mixing an inorganic solid electrolyte, a silane coupling agent, and a first solvent, and then performing a first mixing treatment to obtain the first mixed system.

[0083] Specifically, the first mixing treatment can be carried out by stirring or the like. In some embodiments, after the inorganic solid electrolyte, the silane coupling agent and the first solvent are mixed, they can be stirred for 1 to 7 hours (i.e., the first mixing treatment) to obtain a first mixed system; wherein the stirring time of the first mixing treatment is, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or a range consisting of any two thereof. Through the above-mentioned first mixing treatment process, it is beneficial to improve the dispersion uniformity of the inorganic solid electrolyte and the silane coupling agent in the first solvent, and at the same time, it is beneficial to further improve the grafting efficiency between the silane coupling agent and the inorganic solid electrolyte and other materials and the decomposition efficiency of the silane coupling agent, and it is more conducive to forming a silicon-oxygen bond between the solid electrolyte and the porous nanoparticles, and introducing the first group into the obtained solid electrolyte composite material, further optimizing the performance of the obtained solid electrolyte composite material.

[0084] In addition, the first mixed system may be acidic, and its pH may be 4-5, which is conducive to regulating the reaction rate of the silane coupling agent to prevent an overly rapid reaction, thereby further optimizing the performance of the obtained solid electrolyte composite material.

[0085] In specific implementation, an organic acid may be used to adjust the pH value of the first mixed system. The organic acid may specifically include one or more of formic acid, acetic acid, propionic acid, lactic acid, citric acid, salicylic acid, benzoic acid, oxalic acid, and succinic acid.

[0086] In some embodiments, the process of mixing an inorganic solid electrolyte, a silane coupling agent, and a first solvent (preparation process of a first mixed system) may include: mixing the inorganic solid electrolyte and the first solvent, then adding a silane coupling agent thereto, adjusting the pH to acidic, specifically adjusting the pH to 4 to 5, stirring for 1 hour to 7 hours (first mixing treatment) to obtain a first mixed system.

[0087] Specifically, the silane coupling agent may include one or more of diethylenetriaminopropyltrimethoxysilane, triethoxyvinylsilane, vinyltrimethoxysilane, aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane (KH560), γ-methacryloxypropyltrimethoxysilane (KH570), N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, (3-aminopropyl)triethoxysilane (KH550), (3-aminopropyl)trimethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-aminopropyl(diethoxy)methylsilane, and 3-[(2,3)-glycidoxy]propylmethyldimethoxysilane, but is not limited to the coupling agents mentioned above.

[0088] In the embodiments of the present invention, the silane coupling agent and other materials used can be obtained by conventional methods, such as commercial purchase or homemade by conventional methods in the art. For example, the silane coupling agent KH550 used can be a silane coupling agent model USi-1302 from Nanjing Liansi Chemical Co., Ltd.

[0089] In some embodiments, the amount of the silane coupling agent is such that the mass ratio of the silane coupling agent to the inorganic solid electrolyte is 1% to 10%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any two thereof. The amount of the silane coupling agent within the above range facilitates the introduction of an appropriate amount of the first group into the resulting solid electrolyte composite material, thereby improving the structural stability of the solid electrolyte composite material while further balancing the electrochemical properties of the solid electrolyte composite material, such as reducing its water absorption capacity and improving its ion transport capacity.

[0090] In addition, after the first mixed system is mixed with the porous nanoparticles, a second mixing process may be performed to obtain a second mixed system.

[0091] Specifically, the second mixing treatment can be carried out by stirring or the like. In some embodiments, after the first mixed system is mixed with the porous nanoparticles, the mixture can be stirred for 4 to 12 hours (i.e., the second mixing treatment) to obtain a second mixed system; wherein, the stirring time of the second mixing treatment is, for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or a range consisting of any two thereof. Through the above-mentioned second mixing treatment process, it is beneficial for the porous nanoparticles to be more evenly coated on the surface of the inorganic solid electrolyte to form a more uniform particle layer, and when the first mixed system contains a silane coupling agent, it is also beneficial to further improve the grafting efficiency between the silane coupling agent and the inorganic solid electrolyte and other materials and the decomposition efficiency of the silane coupling agent, and it is more conducive to forming a silicon-oxygen bond connecting the solid electrolyte and the porous nanoparticles, and introducing the first group into the obtained solid electrolyte composite material, further optimizing the performance of the obtained solid electrolyte composite material.

[0092] In addition, the first solvent may include an organic solvent, specifically an alcohol solvent, and the alcohol solvent may include ethanol. In a specific implementation, anhydrous ethanol may be used.

[0093] In addition, the first drying process may include: performing solid-liquid separation on the second mixed system, and then performing a first drying on the obtained solid product to obtain a solid electrolyte composite material.

[0094] In some embodiments, the first drying temperature may be 60-100° C., for example, 60° C., 70° C., 80° C., 90° C., 100° C., or any two thereof.

[0095] In a specific implementation, an inorganic solid electrolyte can be dispersed in a first solvent, and then a silane coupling agent is added to adjust the pH of the system to acidic, specifically, the pH value of the system can be adjusted to 4-5, and then a first mixing treatment is performed (specifically, stirring and dispersing for 1h to 7h) to obtain a first mixed system; porous nanoparticles (or porous nanoparticle materials) are then added to the first mixed system, and a second mixing treatment is performed (specifically, stirring and dispersing for 4h to 12h) to obtain a second mixed system; solid-liquid separation is then performed by filtration or the like to remove the first solvent in the second mixed system, and the obtained solid product is then cleaned with a first cleaning agent, specifically, 3 to 4 times, and then a first drying is performed to obtain a solid electrolyte composite material (i.e., a solid electrolyte material coated with porous nanoparticles).

[0096] Specifically, the first cleaning agent may include at least one of water and an organic solvent, or a mixture of two or more thereof. The organic solvent may include an alcohol solvent, and the alcohol solvent may specifically include ethanol.

[0097] In an embodiment of the present invention, after the second mixed system is subjected to a first drying treatment, the obtained dry product can be directly used as a solid electrolyte composite material; alternatively, the obtained dry product can be used as a solid electrolyte composite material precursor, and the solid electrolyte composite material precursor can be modified with a siloxane compound to introduce a second group to obtain a solid electrolyte composite material. That is, the preparation process of the above-mentioned solid electrolyte composite material can also include: modifying the solid electrolyte composite material precursor with a siloxane compound to obtain a solid electrolyte composite material.

[0098] When the surface of the solid electrolyte composite material precursor is grafted with a silane coupling agent (the first mixed system includes a silane coupling agent), in the process of modifying the solid electrolyte composite material precursor using a siloxane compound, the siloxane compound can be grafted onto the surface of the solid electrolyte composite material precursor by reacting with the silane coupling agent grafted on the surface of the solid electrolyte composite material precursor or the organic group introduced by the silane coupling agent, so as to introduce a second group into the obtained solid electrolyte composite material.

[0099] In some embodiments, the process of modifying a solid electrolyte composite material precursor using a siloxane compound may include: sequentially subjecting a third mixed system including a solid electrolyte composite material precursor, a second solvent, and a siloxane compound to a third mixing treatment and a second drying treatment to obtain a solid electrolyte composite material.

[0100] Specifically, the third mixed system can be acidic, and its pH can be 4 to 5, which is conducive to improving the grafting efficiency of the siloxane compound on the surface of the solid electrolyte composite material precursor. When the surface of the solid electrolyte composite material precursor is grafted with a silane coupling agent, by controlling the pH of the third mixed system within the range of 4 to 5, it is more conducive to regulating the reaction rate of the silane coupling agent and siloxane, avoiding an overly rapid reaction, thereby further optimizing the performance of the obtained solid electrolyte composite material.

[0101] In specific implementation, an organic acid may be used to adjust the pH value of the third mixed system. The organic acid may specifically include one or more of formic acid, acetic acid, propionic acid, lactic acid, citric acid, salicylic acid, benzoic acid, oxalic acid, and succinic acid.

[0102] In some embodiments, the preparation process of the third mixed system may include: mixing a solid electrolyte composite material precursor and a second solvent, then adding a siloxane compound thereto, and adjusting the pH to 4-5 to obtain the third mixed system.

[0103] During the third mixing process, the siloxane compound is grafted onto the surface of the solid electrolyte composite material precursor to introduce a second group into the resulting solid electrolyte composite material. When a silane coupling agent is grafted onto the surface of the solid electrolyte composite material precursor, during the third mixing process of the mixed system, the siloxane compound can react with the silane coupling agent grafted onto the surface of the solid electrolyte composite material precursor or with an organic group introduced by the silane coupling agent, thereby grafting onto the surface of the solid electrolyte composite material precursor to introduce a second group into the resulting solid electrolyte composite material.

[0104] Specifically, the third mixed system may be subjected to a third mixing treatment by stirring, etc. In some specific embodiments, the third mixing treatment may include stirring the third mixed system for 1 to 7 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or a range consisting of any two thereof.

[0105] Specifically, the siloxane compound (or small molecule siloxane compound) may include one or more of 1H,1H,2H,2H-perfluorooctyltriethoxysilane, trimethoxy(3,3,3-trifluoropropyl)silane, hexafluorohexyltriethoxysilane, triethoxymethylsilane, triethoxy(octyl)silane, trimethoxymethylsilane, triethoxy(ethyl)silane, ethoxytrimethylsilane, dimethoxydimethylsilane, 3-(1H,1H,5H octafluoropentyloxy)-1,2-propylene oxide, 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide, octyl glycidyl ether, tert-butyl glycidyl ether, and butyl glycidyl ether, but is not limited to the compounds mentioned above.

[0106] In some embodiments, the amount of the siloxane compound satisfies: the mass ratio of the inorganic solid electrolyte to the siloxane compound is 1:(0.1-0.2), for example, 1:0.1, 1:0.15, 1:0.2 or a range consisting of any two thereof.

[0107] In addition, the second solvent may include an organic solvent, specifically an alcohol solvent, which may include ethanol. In a specific implementation, anhydrous ethanol may be used. The second solvent may be the same as or different from the first solvent.

[0108] In addition, the second drying process may include: performing solid-liquid separation on the third mixed system, and then performing a second drying on the obtained solid product to obtain a solid electrolyte composite material.

[0109] In some embodiments, the second drying temperature may be 60-100° C., for example, 60° C., 70° C., 80° C., 90° C., 100° C., or any two thereof.

[0110] In a specific implementation, the solid electrolyte composite material precursor can be dispersed in a second solvent, and then a siloxane compound is added thereto to adjust the pH of the system to be acidic, specifically, the pH value of the system can be adjusted to 4-5, to obtain a third mixed system; the third mixed system is then subjected to a third mixing treatment (specifically, it can be stirred and dispersed for 1h to 7h); solid-liquid separation is then performed by filtration or the like to remove the second solvent, and the obtained solid product is then washed with a second cleaning agent, specifically, 3 to 4 times, and then a second drying is performed to obtain the solid electrolyte composite material.

[0111] Specifically, the second cleaning agent may include at least one of water and an organic solvent, or a mixture of two or more thereof. The organic solvent may include an alcohol solvent, and the alcohol solvent may specifically include ethanol.

[0112] In the embodiments of the present invention, the inorganic solid electrolytes, porous nanoparticles and other materials used can be obtained by conventional methods for obtaining these materials, such as commercial purchase or self-production by conventional methods in the field. The particle size and particle size distribution and other characteristics of the inorganic solid electrolytes and porous nanoparticles can be regulated by conventional methods, and there is no special limitation on this.

[0113] An embodiment of the present invention further provides a separator comprising a base membrane and a solid electrolyte layer present on at least one surface of the base membrane, wherein the solid electrolyte layer comprises the aforementioned solid electrolyte composite material, or a solid electrolyte composite material produced according to the aforementioned method for producing the solid electrolyte composite material. This separator has advantages corresponding to those of the aforementioned solid electrolyte composite material, which are not further elaborated.

[0114] In an embodiment of the present invention, the moisture value of the diaphragm may be less than or equal to 1750 ppm, and further may be less than or equal to 1500 ppm, for example, less than or equal to 1000 ppm, or less than or equal to 900 ppm, or less than or equal to 700 ppm, or less than or equal to 800 ppm, or less than or less than 600 ppm. It has low moisture properties, which is beneficial to improving battery performance.

[0115] In some specific embodiments, the moisture value of the diaphragm is 50ppm to 920ppm, for example, 50ppm, 100ppm, 200ppm, 300ppm, 320ppm, 350ppm, 380ppm, 400ppm, 410ppm, 420ppm, 430ppm, 450ppm, 460ppm, 480ppm, 500ppm, 530ppm, 540ppm, 570ppm, 600ppm, 620ppm, 650ppm, 670ppm, 680ppm, 700ppm, 720ppm, 730ppm, 750ppm, 780ppm, 800ppm, 820ppm, 840ppm, 860ppm, 880ppm, 900ppm, 920ppm or a range consisting of any two thereof.

[0116] In the embodiment of the present invention, the moisture value of the diaphragm can be characterized by referring to the method for determining trace moisture content in GB / T 6324.8-2014 "Test methods for organic chemical products - Part 8: Determination of moisture in liquid products - Karl Fischer coulometric method".

[0117] In addition, the above-mentioned solid electrolyte layer may also include one or more additives such as binders (or adhesives), dispersants, thickeners and wetting agents. These materials can all be conventional materials in the field. For example, the binder can be the adhesive used in conventional ceramic slurries.

[0118] Specifically, a binder is added to the electrolyte slurry used to form a solid electrolyte layer in order to improve the adhesion and structural stability of the solid electrolyte layer; a dispersant is added to the electrolyte slurry used to form a solid electrolyte layer in order to improve the dispersibility and coating properties; a thickener is added to the electrolyte slurry used to form a solid electrolyte layer in order to improve the storage stability; and a wetting agent is added to the electrolyte slurry used to form a solid electrolyte layer in order to improve the coating uniformity.

[0119] The present invention does not particularly limit the binder in the solid electrolyte layer. For example, the binder may include one or more of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose and cyanoethyl sucrose.

[0120] The present invention does not impose any particular restrictions on the weight percentage of the binder in the solid electrolyte layer, and the amount of addition can be freely selected according to the purpose. For example, the weight percentage of the binder in the solid electrolyte layer can be 0.1% to 30% by weight;

[0121] The present invention does not particularly limit the dispersant. For example, the dispersant may include one or more of polyacrylate copolymer sodium salt, polyacrylate copolymer ammonium salt, and acidic group-containing alkanolate ammonium salt.

[0122] The present invention does not particularly limit the thickener. For example, the thickener may include one or more of sodium carboxymethyl cellulose, fumed silica, modified urea polymers, organic-modified silicates, organic-modified montmorillonites, and organic bentonites.

[0123] The present invention does not particularly limit the wetting agent. For example, the wetting agent can be one or more of polyether siloxane copolymers, organosilicon twin structure copolymers, polyacrylate copolymers, polyether modified silicone oil copolymers and polyoxyethylene alkylamine copolymers.

[0124] The present invention does not impose any particular restrictions on the weight percentage of additives such as dispersants, thickeners, and wetting agents in the solid electrolyte layer; the amount added can be freely selected to suit the intended purpose. For example, the weight percentage of each additive in the solid electrolyte layer (i.e., the weight percentage of the additive in the solid electrolyte layer) can be 0.1 wt% to 3 wt%.

[0125] For example, the mass percentage of the dispersant in the solid electrolyte layer may be 0.1 wt% to 3 wt%; the mass percentage of the thickener in the solid electrolyte layer may be 0.1 wt% to 3 wt%; and the mass percentage of the wetting agent in the solid electrolyte layer may be 0.1 wt% to 3 wt%.

[0126] Specifically, the solid electrolyte layer can be provided on one side of the base membrane, or the solid electrolyte layer can be provided on both the front and back surfaces of the base membrane. When a solid electrolyte layer is provided on one side of the base membrane, when the diaphragm is applied to the battery, the solid electrolyte layer can be provided on the side of the base membrane facing the positive electrode sheet, or on the side of the base membrane facing the negative electrode sheet. Relatively speaking, when the solid electrolyte layer is provided on the side of the base membrane facing the positive electrode sheet, it is beneficial to further improve the electrochemical performance of the battery. The reason for this is that the solid electrolyte layer is more suitable for the positive electrode system. During the charge and discharge process of the battery, the positive electrode sheet undergoes the extraction and embedding of active ions. When the solid electrolyte layer is provided on the side of the diaphragm facing the positive electrode sheet, it is more conducive to the extraction and embedding process of active ions of the positive electrode sheet, thereby reducing the internal resistance of the battery. At the same time, the electrochemical side reaction of the active ions (such as lithium ions) in the positive electrode side ion state with the solid electrolyte composite material is more difficult, which can reduce the influence of the battery charge and discharge process on the properties such as the air permeability of the diaphragm, thereby improving the service life of the diaphragm and improving the electrochemical performance of the battery.

[0127] The separator of the embodiment of the present invention can be applied to all-solid-state batteries or semi-solid-state batteries. It has properties such as low moisture content and high ionic conductivity, which can improve battery performance.

[0128] In some embodiments, the thickness of the solid electrolyte layer can be 0.5 to 4 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm or any two thereof, which is beneficial to improving the ion transport performance of the membrane.

[0129] In an embodiment of the present invention, the thickness of the solid electrolyte layer refers to the thickness of the solid electrolyte layer on one side of the diaphragm. For example, when solid electrolyte layers are provided on both the front and back surfaces of the base membrane, the thickness of the solid electrolyte layer refers to the thickness of the solid electrolyte layer on either side of the base membrane.

[0130] In some embodiments, the thickness of the base film is 3 to 20 μm, for example, 3 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm or a range consisting of any two of them, which is conducive to further improving the structural stability and ion transmission capacity of the diaphragm and other performance.

[0131] In an embodiment of the present invention, the base membrane is a porous membrane substrate. In some embodiments, the porosity of the base membrane can be 20% to 70%, for example, 20%, 30%, 40%, 50%, 60%, 70% or a range composed of any two of them, which is beneficial to further improve the structural stability and ion transmission capacity of the diaphragm and other performance.

[0132] In some embodiments, the base film may include one or more of polyethylene (PE) porous film, polypropylene porous film, polyimide porous film, polyvinylidene fluoride porous film, non-woven fabric, polyethylene terephthalate (PET) porous film, aramid fiber porous film, etc.

[0133] In embodiments of the present invention, a solid electrolyte layer can be formed on the surface of a base film by coating. Specifically, an electrolyte slurry for forming the solid electrolyte layer can be applied to the surface of the base film by a micro-gravure reverse coating process to form the solid electrolyte layer and produce a separator. The steps involved are all conventional operations of the micro-gravure reverse coating process and are not particularly limited thereto. The electrolyte slurry includes the above-mentioned solid electrolyte composite material.

[0134] In some embodiments, the electrolyte slurry is coated on the surface of the base membrane and then dried at 50-100° C. to form a solid electrolyte layer on the surface of the base membrane to produce a separator.

[0135] An embodiment of the present invention further provides a battery including the above-mentioned separator. The battery has advantages corresponding to those of the above-mentioned solid electrolyte composite material, which will not be described in detail.

[0136] Specifically, the above-mentioned battery may be a semi-solid-state battery or an all-solid-state battery.

[0137] Generally speaking, a battery includes a battery cell and a shell that encapsulates the battery cell. The battery cell includes a positive electrode sheet, a separator and a negative electrode sheet. The separator is located between the positive electrode sheet and the negative electrode sheet and is used to separate the positive electrode sheet and the negative electrode sheet to prevent the positive electrode sheet and the negative electrode sheet from short-circuiting. At the same time, the separator is also used to allow active ions such as lithium ions to pass through, so that active ions such as lithium ions can be deintercalated between the positive and negative electrodes, thereby realizing the battery's charging and discharging process.

[0138] In the embodiment of the present invention, conventional shell materials in the art may be used to encapsulate the battery cell. The shell may include, for example, a soft packaging material such as an aluminum-plastic film, but is not limited thereto.

[0139] Generally, the positive electrode sheet includes a positive electrode collector and a positive electrode coating located on at least one side of the positive electrode collector. Specifically, the positive electrode coating can be provided on one side of the positive electrode collector, or on two opposite sides of the positive electrode collector in the thickness direction (i.e., the front and back surfaces of the positive electrode collector).

[0140] Specifically, the positive electrode coating (positive electrode active material layer) includes materials such as a positive electrode active material, a conductive agent, and a binder. In addition, the positive electrode coating may also include a solid electrolyte. These materials in the positive electrode coating can all be conventional materials in the art. For example, the positive electrode active material may include one or more of lithium cobalt oxide, lithium iron phosphate, and a ternary material. The ternary material may include a nickel-cobalt-manganese ternary material and / or a nickel-cobalt-aluminum ternary material. The conductive agent may include conductive carbon, specifically one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, Ketjen black, and carbon fiber. The binder may include one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, polyvinyl chloride, carboxylated polyvinyl chloride, a polymer containing ethylene oxide, polyvinyl pyrrolidone, and polyurethane.

[0141] When the positive electrode coating further includes a solid electrolyte, the solid electrolyte in the positive electrode coating and the solid electrolyte in the separator may be made of the same or different materials.

[0142] In some embodiments, in the positive electrode coating, the mass percentage of the positive electrode active material can be 75% to 90%, the mass percentage of the solid electrolyte can be 10% to 25%, the mass percentage of the conductive agent can be 0.2% to 1.0%, and the mass percentage of the binder can be 0.5% to 1.5%.

[0143] The embodiment of the present invention may adopt a conventional positive electrode current collector in the art, for example, the positive electrode current collector includes aluminum foil.

[0144] In the embodiments of the present invention, the positive electrode sheet can be prepared by a conventional coating method in the art. Specifically, the components used to form the positive electrode coating, such as the positive electrode active material, conductive agent, and binder, can be dispersed in a third solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry. In addition, the positive electrode material can also include a solid electrolyte material. The positive electrode slurry is coated on the surface of the positive electrode current collector and subjected to drying, roller pressing, and other processes to produce the positive electrode sheet. The coating, drying, and roller pressing processes involved are conventional operations for preparing positive electrode sheets using the coating method and are not particularly limited thereto.

[0145] In addition, the negative electrode sheet includes a negative electrode current collector and a negative electrode coating located on at least one side surface of the negative electrode current collector. Specifically, the negative electrode coating can be provided on one side surface of the negative electrode current collector, or the negative electrode coating can be provided on both sides of the negative electrode current collector in the thickness direction.

[0146] Specifically, the negative electrode coating (negative electrode active material layer) may include materials such as negative electrode active material, conductive agent and binder. These materials may be conventional materials in the field. For example, the negative electrode active material may include one or more of silicon-based materials, silicon-based materials, silicon-carbon-based materials, graphite, metallic lithium, lithium-indium alloy materials, etc., wherein the graphite may include artificial graphite and / or natural graphite; the conductive agent may include one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, Ketjen black, and carbon fiber; the binder may include one or more of sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0147] The embodiment of the present invention may adopt a conventional negative electrode current collector in the art, for example, the negative electrode current collector includes copper foil.

[0148] In an embodiment of the present invention, the negative electrode sheet can be prepared by conventional methods in the art, for example, by a coating method. Specifically, the components used to form the negative electrode coating, such as the negative electrode active material, the conductive agent, and the binder, can be dispersed in a fourth solvent, and the fourth solvent includes, for example, water (specifically, deionized water can be used), to prepare a negative electrode slurry, which is then coated on the surface of the negative electrode current collector. After drying, rolling, and other processes, the negative electrode sheet is obtained.

[0149] In general, when the battery is a semi-solid-state battery, the battery also includes an electrolyte. The embodiments of the present invention may use conventional electrolytes in the art. For example, the electrolyte is a non-aqueous electrolyte, which may specifically include an organic solvent and an electrolyte salt. The organic solvent may include, for example, one or more of ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), vinylene carbonate (VC), and propylene carbonate (PC). The electrolyte salt may include a lithium salt, such as lithium hexafluorophosphate (LiPF6), but is not limited thereto.

[0150] In an embodiment of the present invention, the battery can be prepared by conventional methods in the field. For example, taking the preparation process of a semi-solid-state battery as an example, the preparation process may include: assembling the positive electrode sheet, the separator, and the negative electrode sheet layer into a battery cell, and then packaging it with a shell, and after processes such as liquid injection (injecting electrolyte into the shell) and formation, a semi-solid-state battery is obtained. The processes involved are all conventional preparation processes for semi-solid-state batteries and are not particularly limited thereto.

[0151] The present invention is further described below through specific examples. In the following examples and comparative examples, the test methods for characteristics such as the density and thickness of the particle layer in the solid composite material, the type and content of the first group, the type and content of the second group, and the specific surface area of ​​the solid electrolyte composite material are similar to those described above and will not be repeated in detail.

[0152] Example 1

[0153] 1. Preparation of positive electrode

[0154] Lithium cobalt oxide, acetylene black and PVDF were mixed in a mass ratio of 90:5:5 and added to NMP to prepare a positive electrode slurry;

[0155] The positive electrode slurry is coated on the front and back surfaces of the aluminum foil. After drying and roller pressing, positive electrode coatings are formed on the front and back surfaces of the aluminum foil to prepare a positive electrode sheet.

[0156] 2. Preparation of negative electrode sheet

[0157] Artificial graphite, acetylene black and SBR emulsion were mixed and added into deionized water to prepare negative electrode slurry; wherein the mass ratio of artificial graphite, acetylene black and SBR was 90:5:5;

[0158] The negative electrode slurry is coated on the front and back surfaces of the copper foil. After drying and roller pressing, negative electrode active material layers are formed on the front and back surfaces of the copper foil to prepare a negative electrode sheet.

[0159] 3. Preparation of solid electrolyte composite materials

[0160] The inorganic solid electrolyte LATP is dispersed in anhydrous ethanol, and then a silane coupling agent KH560 is added, the pH value is adjusted to 4, and then the mixture is stirred and dispersed for 6 hours to obtain a first mixed system; porous nanoparticles (or porous nanoparticle materials) are then added to the first mixed system and stirred and dispersed for 8 hours; the first solvent is then removed by filtration, and the obtained solid product is washed three times with a mixed solution of deionized water and anhydrous ethanol, and then dried at 80°C to obtain a solid electrolyte composite material.

[0161] 4. Preparation of diaphragm

[0162] The solid electrolyte composite material prepared above was dispersed in pure water, and the dispersant BYK ET 3004 (BYK additive), the adhesive LIB-S103 (Shanghai Sanrui Polymer Materials Co., Ltd.), the thickener CMC (Shandong Dongda Cellulose Co., Ltd.) and the wetting agent BYK-LP G 26034 (BYK additive) were added according to the metered ratio to prepare an electrolyte slurry; wherein, the mass proportion of the dispersant is 1.5%, the mass proportion of the adhesive is 6.0%, the mass proportion of the thickener is 0.3%, and the mass proportion of the wetting agent is 0.3%. "Mass proportion" refers to the ratio of the mass of the component to the sum of the mass of the solid electrolyte composite material, dispersant, adhesive, thickener and wetting agent;

[0163] The electrolyte slurry is coated on one side of the base membrane through a micro-gravure coating process and dried at 70°C to form a solid electrolyte layer on the surface of the base membrane; wherein the base membrane is made of a PE porous membrane (purchased from Shenzhen Xingyuan Material Technology Co., Ltd., with a thickness of 9 μm and a porosity of 40%), and the thickness of the solid electrolyte layer is 2 μm.

[0164] 5. Preparation of batteries

[0165] The positive electrode sheet, separator and negative electrode sheet are stacked and assembled into a stacked battery cell, which is then encapsulated in an aluminum-plastic film shell. After liquid injection and formation processes, a semi-solid-state battery is produced.

[0166] The side of the diaphragm provided with the solid electrolyte layer faces the positive electrode sheet.

[0167] The electrolyte used is composed as follows: the organic solvents of the electrolyte are ethylene carbonate (EC), ethyl methyl carbonate (EMC) and propylene carbonate (PC), the volume ratio of which is EC:EMC:PC=1:1:1, and the concentration of LiPF6 in the electrolyte is 1 mol / L.

[0168] Examples 2 to 29 and Comparative Examples 1 to 3: The difference from Example 1 lies in the use of the solid electrolyte composite materials and their preparation methods. The remaining steps and conditions are the same as in Example 1. The differences in the solid electrolyte composite materials are shown in Tables 1, 2, and 3. The preparation methods of the solid electrolyte composite materials of Examples 2 to 29 and Comparative Examples 1 to 3 are as follows.

[0169] The preparation methods of the solid electrolyte composite materials of Examples 2 to 4 are basically the same as those of Example 1, except that the conditions such as the average particle size of the porous nanoparticles are different, as shown in Tables 1, 2 and 3 for details.

[0170] The preparation methods of the solid electrolyte composite materials of Examples 5 to 9 are basically the same as those of Example 1, except that the conditions such as the particle size distribution D of the porous nanoparticles are different, as shown in Tables 1, 2 and 3 for details.

[0171] The preparation methods of the solid electrolyte composite materials of Examples 10 to 12 are basically the same as those of Example 1, except that the conditions such as the average pore size of the porous nanoparticles are different, as shown in Tables 1, 2 and 3.

[0172] Example 13: The preparation method of this example is basically the same as that of Example 2, except that the porous nanoparticles are ZIF-67, as shown in Table 1, Table 2 and Table 3.

[0173] The preparation methods of the solid electrolyte composite materials of Examples 14 to 15 are basically the same as those of Example 2, except that the mass ratios of the porous nanoparticles to the LATP are different, and the thicknesses of the particle layers in the prepared solid electrolyte composite materials are different, as shown in Tables 1, 2, and 3.

[0174] The preparation methods of the solid electrolyte composite materials of Examples 16 and 17 are basically the same as those of Example 2, except that different silane coupling agents are used. See Table 1, Table 2 and Table 3 for details.

[0175] The preparation methods of the solid electrolyte composite materials of Examples 18 to 19 are basically the same as those of Example 2, except that the amount of silane coupling agent used (mass ratio of silane coupling agent to LATP) is different, as shown in Tables 1, 2 and 3.

[0176] The preparation method of the solid electrolyte composite material of Example 20 is basically the same as that of Example 2, except that no silane coupling agent is added to the first mixing system (the prepared solid electrolyte composite material does not contain the first group), see Table 1, Table 2 and Table 3 for details.

[0177] The preparation methods of the solid electrolyte composite materials of Comparative Examples 1 to 3 are basically the same as those of Example 1, except that the conditions such as the average particle size of the porous nanoparticles are different, as shown in Table 1, Table 2 and Table 3.

[0178] The difference between Example 21 and Example 2 is that the solid electrolyte composite material of Example 21 contains a second group. The preparation process of the solid electrolyte composite material of Example 21 is as follows: the inorganic solid electrolyte LATP is dispersed in anhydrous ethanol, and then the silane coupling agent KH560 is added, the pH value is adjusted to 4, and then stirred and dispersed for 6 hours to obtain a first mixed system; porous nanoparticles (or porous nanoparticle materials) are then added to the first mixed system and stirred and dispersed for 8 hours; the first solvent is then removed by filtration, and the obtained solid product is washed three times with a mixed solution of deionized water and anhydrous ethanol, and then dried at 80°C to obtain a solid electrolyte composite material precursor; then, the above-mentioned solid electrolyte composite material precursor is dispersed in anhydrous ethanol, and then dimethoxydimethylsilane is added thereto (the mass ratio of dimethoxydimethylsilane to the solid electrolyte composite material precursor is 1%), the pH value is adjusted to 4, and then stirred and dispersed for 6 hours, and then the solvent is removed by filtration, and the obtained solid product is washed three times with a mixed solution of deionized water and anhydrous ethanol, and then dried at 80°C to obtain a solid electrolyte composite material.

[0179] The preparation methods of the solid electrolyte composite materials of Examples 22 to 25 are basically the same as those of Example 21, except that the mass ratios of dimethoxydimethylsilane to the solid electrolyte composite material precursor are different, as shown in Tables 1, 2 and 3.

[0180] The preparation method of the solid electrolyte composite material of Example 26 is basically the same as that of Example 23, except that the siloxane compound used is trimethoxy (3,3,3-trifluoropropyl) silane, as shown in Tables 1, 2 and 3.

[0181] The preparation method of the solid electrolyte composite material of Example 27 is basically the same as that of Example 26, except that the silane coupling agent used is KH550, as shown in Table 1, Table 2 and Table 3.

[0182] The preparation method of the solid electrolyte composite material of Example 28 is basically the same as that of Example 23, except that the silane coupling agent used is KH550, as shown in Table 1, Table 2 and Table 3.

[0183] The preparation method of the solid electrolyte composite material of Example 29 is basically the same as that of Example 23, except that the silane coupling agent used is KH570, as shown in Table 1, Table 2 and Table 3.

[0184] The ratio of the particle size of the porous nanoparticles to the inorganic solid electrolyte in the solid electrolyte composite material, the particle size D2 of the inorganic solid electrolyte, the particle size D1 of the porous nanoparticles, the particle size distribution D of the porous nanoparticles, the average pore size of the porous nanoparticles, the specific surface area of ​​the porous nanoparticles, the type of porous nanoparticles, the mass ratio of the porous nanoparticles to the inorganic solid electrolyte, the density of the particle layer, the thickness of the particle layer, the mass ratio of the silane coupling agent to the inorganic solid electrolyte, the type of the silane coupling agent, the type and molar content of the first group in the solid electrolyte composite material, the type of the siloxane compound, the mass ratio of the siloxane compound to the solid electrolyte composite material precursor, the type and molar content of the second group in the solid electrolyte composite material, the specific surface area of ​​the solid electrolyte composite material, and other conditions are summarized in Tables 1, 2, and 3.

[0185] The following performance tests were performed on the solid electrolytes / batteries of the embodiments and comparative examples, and the results are shown in Table 4.

[0186] 1. Moisture value test of diaphragm

[0187] The moisture value of the diaphragm was determined by referring to the method for determining trace moisture content in GB / T 6324.8-2014 "Test methods for organic chemical products Part 8: Determination of moisture in liquid products - Karl Fischer coulometric method".

[0188] 2. Battery initial performance test

[0189] The first efficiency of the battery is determined by referring to the method for determining the first-week coulombic efficiency (first efficiency of the battery) in GB / T 37201-2018 "Test method for first discharge specific capacity and first charge and discharge efficiency of lithium nickel cobalt manganese oxide electrochemical performance test".

[0190] 3. Battery rate performance test

[0191] The rate discharge performance of the battery is determined by referring to the measurement method in GBT 31486-2024 "Electrical Performance Requirements and Test Methods for Power Batteries for Electric Vehicles". The discharge rate in this application is 3C, that is, the battery is discharged at a 3C rate to obtain a discharge capacity Q1. The 3C discharge capacity retention rate of the battery = Q1 / Q0, where Q0 is the initial capacity of the battery before 3C rate discharge (Q0 is the rated capacity of the battery calibrated at 0.2C).

[0192] 4. Battery capacity retention test after 500 cycles at 45°C.

[0193] The battery's cycling performance was measured according to the method specified in GBT 31484-2015, "Cycle Life Requirements and Test Methods for Power Batteries for Electric Vehicles." In this application, the test temperature was 45°C, the charge and discharge rate was 1C, and the number of cycles was 500. The capacity retention rate (the ratio of the battery's capacity after 500 cycles to the initial capacity) after 500 cycles at 45°C is shown in Table 3.

[0194] Table 1

[0195]

[0196] Table 2

[0197]

[0198] Table 3

[0199]

[0200] Table 4

[0201]

[0202] As can be seen from Table 4, relative to Comparative Examples 1 to 3, in Examples 1 to 29, a particle layer is formed on the surface of the inorganic solid electrolyte in the solid electrolyte composite material, and the ratio of the particle size of the porous nanoparticles in the particle layer to the particle size of the inorganic solid electrolyte is controlled within the range of 0.01 to 1. This can take into account the electrochemical properties such as low water absorption capacity and ionic conductivity of the solid electrolyte composite material, maintain a low moisture value of the diaphragm, and improve the first efficiency, rate performance and cycle performance of the battery.

[0203] In addition, it can be seen from Table 4 that when the ratio of the particle size of the porous nanoparticles to the particle size of the inorganic solid electrolyte is in the range of 0.05 to 0.5, while maintaining a low moisture value of the separator, it is beneficial to further improve the battery's first efficiency, 3C discharge capacity retention rate, and capacity retention rate after 500 cycles at 45°C, that is, further improve the battery's first efficiency, rate performance, and cycle performance. For example, compared with Examples 1 and 4, Examples 2 and 3 can further improve the battery's first efficiency, 3C discharge capacity retention rate, and capacity retention rate after 500 cycles at 45°C.

[0204] In addition, it can be seen from Table 4 that when the particle size distribution D of the porous nanoparticles is in the range of 0.5 to 1.8, especially in the range of 0.8 to 1.5, it is beneficial to further reduce the moisture value of the diaphragm, while taking into account the improvement of the first efficiency, rate performance and cycle performance of the battery. For example, compared with Example 5 and Example 9, Example 2, Example 6 to Example 8 can further reduce the moisture value of the diaphragm, while taking into account the improvement of the first efficiency, 3C discharge capacity retention rate and 45°C cycle 500 cycles of the battery. In particular, Example 2 and Example 7 further control the particle size distribution D of the porous nanoparticles in the range of 0.8 to 1.5, which is beneficial to further reduce the moisture value of the diaphragm and improve the first efficiency, rate performance and cycle performance of the battery.

[0205] In addition, it can be seen from Table 4 that when the specific surface area of ​​porous nanoparticles is between 150 and 2000 g / m 2 In the range of 1000~1800g / m 2 When the moisture content of the diaphragm is within the above range, it is beneficial to further reduce the moisture content of the diaphragm and improve the first efficiency, rate performance, and cycle performance of the battery. For example, compared with Example 12, the diaphragms of Examples 10 and 11 have lower moisture contents, and the batteries have higher first efficiency, rate performance, and cycle performance. In particular, Example 10 can more significantly reduce the moisture content of the diaphragm and improve the first efficiency and rate performance of the battery.

[0206] In addition, it can be seen from Table 4 that when the thickness of the granular layer is in the range of 50nm to 5000nm, or the density of the granular layer is in the range of 0.1 to 0.3g / cm 3 When the moisture content of the separator is within the range, it is beneficial to further reduce the moisture content of the separator and improve the first efficiency, rate performance and cycle performance of the battery. For example, compared with Example 15, the separators of Examples 2 and 14 have lower moisture content, and the batteries have higher first efficiency rate performance and cycle performance.

[0207] In addition, compared with Example 20, Examples 1 to 19 and Examples 21 to 29 introduce a silane coupling agent in the process of preparing the solid electrolyte composite material. The solid electrolyte composite material includes silicon-oxygen bonds connected to the surface of porous nanoparticles and inorganic solid electrolytes, which can further improve the structural stability and other properties of the solid electrolyte composite material while maintaining the low water absorption capacity and high ionic conductivity of the solid electrolyte composite material.

[0208] In addition, Examples 21 to 29 further introduce a second group into the solid electrolyte composite material, which helps to further reduce the moisture value of the separator and improve the first efficiency, rate performance and cycle performance of the battery.

[0209] Furthermore, Table 4 shows that when the molar content of the second group in the solid electrolyte composite material is within the range of 0.1% to 5%, it is beneficial to further improve the battery's initial efficiency, rate performance, and cycle performance while maintaining a low moisture content in the separator. For example, compared to Examples 21 and 25, Examples 22 to 24 can further improve the battery's initial efficiency, rate performance, and cycle performance.

[0210] In the description of the present invention, terms such as "first" and "second" are used only for descriptive purposes, such as distinguishing between components to more clearly illustrate / explain the technical solution, and cannot be understood as indicating or implying the number of the indicated technical features or the order with substantial significance.

[0211] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid electrolyte composite material, characterized in that: The invention comprises an inorganic solid electrolyte and a particle layer existing on the surface of the inorganic solid electrolyte. The particle layer comprises porous nanoparticles. The ratio of the particle size of the porous nanoparticles to the particle size of the inorganic solid electrolyte is 0.01-1.

2. The solid electrolyte composite material according to claim 1, characterized in that The ratio of the particle size of the porous nanoparticles to the particle size of the inorganic solid electrolyte is 0.05 to 0.

5.

3. The solid electrolyte composite material according to claim 1 or 2, characterized in that The average pore size of the porous nanoparticles is 0.5 nm to 5 nm; and / or, the particle size distribution of the porous nanoparticles satisfies 0.5≤(D90-D10) / D50≤1.8, preferably 0.8≤(D90-D10) / D50≤1.5; and / or, the particle size of the porous nanoparticles is 20 to 1500 nm; And / or, the specific surface area of ​​the porous nanoparticles is 150 to 2000 g / m 2 , preferably 1000~1800g / m 2 .

4. The solid electrolyte composite material according to any one of claims 1 to 3, characterized in that: The density of the granular layer is 0.1 to 2.0 g / cm 3 , preferably 0.1 to 0.3 g / cm 3 ; And / or, the thickness of the particle layer is 50 to 5000 nm, preferably 50 to 1200 nm.

5. The solid electrolyte composite material according to any one of claims 1 to 4, characterized in that: The solid electrolyte composite material includes silicon-oxygen bonds connecting the porous nanoparticles and the surface of the inorganic solid electrolyte.

6. The solid electrolyte composite material according to any one of claims 1 to 5, characterized in that: The solid electrolyte composite material further includes a first group; Preferably, the first group includes one or more of vinyl, epoxy, and amino groups; Preferably, the molar content of the first group in the solid electrolyte composite material is 0.1% to 5%.

7. The solid electrolyte composite material according to any one of claims 1 to 6, characterized in that: The specific surface area of ​​the solid electrolyte composite material is 50 to 500 g / m 2 .

8. A method for preparing the solid electrolyte composite material according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing an inorganic solid electrolyte, a first solvent and porous nanoparticles to obtain a second mixed system; and then performing a first drying process on the second mixed system to obtain the solid electrolyte composite material.

9. The method for preparing a solid electrolyte composite material according to claim 8, characterized in that: The mass ratio of the porous nanoparticles to the inorganic solid electrolyte is 0.1% to 40%.

10. The method for preparing a solid electrolyte composite material according to claim 8 or 9, characterized in that: The process of mixing the inorganic solid electrolyte, the first solvent and the porous nanoparticles comprises: mixing a first mixed system comprising the inorganic solid electrolyte and the first solvent with the porous nanoparticles, and stirring for 4 to 12 hours to obtain a second mixed system; Preferably, the first mixing system further comprises a silane coupling agent; Preferably, the first mixed system is acidic, and preferably the pH of the first mixed system is 4 to 5; Preferably, the preparation process of the first mixed system comprises: mixing an inorganic solid electrolyte and a first solvent, then adding a silane coupling agent thereto, adjusting the pH to 4 to 5, and stirring for 1 hour to 7 hours to obtain the first mixed system; Preferably, the mass ratio of the silane coupling agent to the inorganic solid electrolyte is 1% to 10%; Preferably, the silane coupling agent includes one or more of diethylenetriaminopropyltrimethoxysilane, triethoxyvinylsilane, vinyltrimethoxysilane, aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-aminopropyl(diethoxy)methylsilane, and 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane.

11. The method for preparing a solid electrolyte composite material according to any one of claims 8 to 10, characterized in that: The first drying process includes: performing solid-liquid separation on the second mixed system, and then performing a first drying on the obtained solid product to obtain the solid electrolyte composite material; preferably, the first drying temperature is 60-100°C.

12. A diaphragm, characterized in that: The invention comprises a base film and a solid electrolyte layer present on at least one side surface of the base film, wherein the solid electrolyte layer comprises the solid electrolyte composite material according to any one of claims 1 to 7 or a solid electrolyte composite material prepared according to the preparation method of the solid electrolyte composite material according to any one of claims 8 to 11.

13. The diaphragm according to claim 12, characterized in that The moisture value of the diaphragm is less than or equal to 1500 ppm.

14. A battery, characterized in that: The diaphragm according to claim 12 or 13 is included.

15. The battery according to claim 14, characterized in that The battery is a semi-solid-state battery or an all-solid-state battery.

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