Electrolyte material and preparation method thereof, diaphragm and battery

Abstract

The invention provides an electrolyte material and a preparation method thereof, a diaphragm and a battery, the electrolyte material comprises an inorganic solid electrolyte matrix and a porous coating layer existing on the surface of the inorganic solid electrolyte matrix, and the numerical ratio of the specific surface area to the volume of the electrolyte material is (0.6-12) * 10 < 5 > g <-1 >. Cm <-1 >. The electrochemical properties such as reduction of the water absorption capacity of the electrolyte material and improvement of the ionic conductivity of the electrolyte material can be considered.

Description

Technical Field

[0001] The present application relates to the field of electrolyte materials, and in particular to an electrolyte material and a preparation method thereof, a separator and a battery. Background Art

[0002] Inorganic solid electrolytes are common ion-conducting materials widely used in solid-state batteries. However, due to their strong hydrophilicity and other properties, they are prone to water absorption when used in batteries, which in turn affects the battery's electrochemical performance. Therefore, how to reduce the water absorption of electrolyte materials and improve their electrochemical properties, such as ionic conductivity, is a technical problem that needs to be solved in this field. Summary of the Invention

[0003] The present invention provides an electrolyte material and a preparation method thereof, a diaphragm and a battery, which can simultaneously reduce the water absorption capacity of an inorganic solid electrolyte material and improve its electrochemical properties such as ionic conductivity, effectively overcoming the defects of the prior art.

[0004] In one aspect of the present invention, an electrolyte material is provided, comprising an inorganic solid electrolyte matrix and a porous coating layer present on the surface of the inorganic solid electrolyte matrix, wherein the ratio of the specific surface area to the volume of the electrolyte material is (0.6 to 12)*10 5 g -1 cm -1 .

[0005] According to one embodiment of the present invention, the density of the porous coating layer is 0.5 to 1.5 g / cm 3 .

[0006] According to one embodiment of the present invention, the ratio of the specific surface area to the volume of the electrolyte material is (3 to 10)*10 5 g -1 cm -1 ; and / or, the specific surface area of ​​the electrolyte material is (5-60)*10 4 cm 2 / g, preferably (11 to 45)*10 4 cm 2 / g.

[0007] According to one embodiment of the present invention, the ratio of the thickness of the porous coating layer to the average particle size of the inorganic solid electrolyte matrix is ​​less than or equal to 0.5, preferably 0.05 to 0.3; and / or the thickness of the porous coating layer is 5 to 430 nm, preferably 120 to 300 nm; and / or the average particle size of the inorganic solid electrolyte matrix is ​​100 to 2000 nm.

[0008] According to one embodiment of the present invention, the mass ratio of the porous coating layer to the electrolyte material is 0.1% to 10%, preferably 1% to 10%.

[0009] According to one embodiment of the present invention, the average pore diameter of the porous coating layer is 0.5 to 50 nm.

[0010] According to one embodiment of the present invention, the porous coating layer comprises an inorganic oxide, and preferably the inorganic oxide comprises one or more of alumina, zirconia, titania, and silica.

[0011] According to one embodiment of the present invention, the electrolyte material contains a first group, which includes one or more of vinyl, epoxy, and amino groups; preferably, the molar content of the first group in the electrolyte material is 0.1% to 5%.

[0012] Another aspect of the present invention provides a method for preparing the above-mentioned electrolyte material, comprising the following steps: subjecting a mixed solution containing an inorganic solid electrolyte matrix, a pore-forming agent, a coating material precursor and a first solvent to a sol-gel reaction to form a coating film layer on the surface of the inorganic solid electrolyte matrix to obtain an electrolyte precursor; and subjecting the electrolyte precursor to a sintering treatment to form the coating film layer on the surface of the inorganic solid electrolyte matrix to the porous coating layer to obtain the electrolyte material.

[0013] According to one embodiment of the present invention, the pore former includes one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acid, starch, nanocellulose, and polyethylene glycol; and / or, based on the total mass of the inorganic solid electrolyte matrix, the pore former and the coating material precursor, the mass proportion of the inorganic solid electrolyte matrix is ​​55% to 85%, the mass proportion of the pore former is 10% to 20%, and the mass proportion of the coating material precursor is 5% to 35%; and / or, the coating material precursor includes an inorganic oxide precursor; preferably, the inorganic oxide precursor includes tetraethyl orthosilicate and / or tetraethyl titanate; and / or, the mixed solution is alkaline, preferably, the pH of the mixed solution is 8 to 9; and / or, the sol-gel reaction time is 1 to 6 hours.

[0014] According to one embodiment of the present invention, the sintering process is performed at a temperature of 700 to 1200° C. and for a time of 3 to 7 hours.

[0015] According to one embodiment of the present invention, the preparation method of the above-mentioned electrolyte material further includes: after the sintering treatment, modifying the obtained sintered product with a silane coupling agent to obtain the electrolyte material; preferably, the mass ratio of the sintered product to the silane coupling agent is 99:1 to 93:7; preferably, the temperature of the modification treatment is 30 to 60°C, and the time is 2 to 12 hours; preferably, the process of modifying the obtained sintered product with a silane coupling agent includes: after the sintering treatment, mixing the obtained sintered product with a second solvent, adjusting the pH of the system to 4 to 9, and then adding the silane coupling agent thereto, and modifying the mixture at 30 to 60°C for 2 to 12 hours. 2h, the electrolyte material is prepared; 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.

[0016] Another aspect of the present invention provides a separator comprising a base membrane and an electrolyte layer present on at least one surface of the base membrane, wherein the electrolyte layer comprises the above-mentioned electrolyte material or an electrolyte material prepared according to the above-mentioned method for preparing the electrolyte material.

[0017] Another aspect of the present invention provides a battery comprising the above separator.

[0018] According to one embodiment of the present invention, the battery is a semi-solid-state battery or an all-solid-state battery.

[0019] The electrolyte material, preparation method thereof, separator and battery provided by the present invention have a porous coating layer on the surface of the inorganic solid electrolyte matrix, and the ratio of the specific surface area to volume of the electrolyte material is (0.6 to 12)*10 5 g -1 cm -1Under the composition and structural system of such an electrolyte material, the inorganic solid electrolyte matrix can be protected by the porous coating layer, reducing the contact between the inorganic solid electrolyte matrix and water, thereby reducing the water absorption performance of the electrolyte material, and then reducing the moisture content of the electrolyte material, improving its electrochemical performance. At the same time, the porous structure of the porous coating layer can provide a transmission channel for active ions such as lithium ions, thereby ensuring the electrochemical properties such as ionic conductivity of the electrolyte material. Therefore, the present invention can reduce the water absorption capacity of the inorganic solid electrolyte material and improve its electrochemical properties such as ionic conductivity. The electrolyte material can be used as a solid electrolyte in solid-state batteries, specifically in all-solid-state batteries or semi-solid-state batteries, to improve battery performance, specifically improving the high-temperature cycle performance and room-temperature cycle performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of an electrolyte material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] 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.

[0022] Due to their strong hydrophilicity, inorganic solid electrolytes are prone to water absorption when used in batteries, which in turn affects the battery's electrochemical performance. Therefore, reducing the water absorption of electrolyte materials and improving their electrochemical properties, such as ionic conductivity, are urgent technical issues in this field.

[0023] According to the long-term research of the inventors of this application, inorganic solid electrolyte materials have extremely high affinity for water and will absorb water when stored in the air. The absorbed water will have a serious impact on the electrochemical properties of the inorganic solid electrolyte materials, thereby affecting the performance of the battery.

[0024] The use of hydrophobic materials to coat inorganic solid electrolytes to form a hydrophobic coating layer on the surface of the inorganic solid electrolyte is expected to serve as a low-moisture modification method for inorganic solid electrolytes, thereby improving the surface hydrophobicity of inorganic solid electrolyte materials and reducing their water absorption capacity. Common hydrophobic materials include aluminum oxide, fluorine-containing polymers, silane coupling agents, polydopamine materials, etc.

[0025] However, when a hydrophobic material is used to coat the surface of an inorganic solid electrolyte, a dense coating with poor ionic conductivity is usually formed on the surface of the inorganic solid electrolyte, affecting the inorganic solid electrolyte material's ability to transport active ions such as lithium ions, thereby affecting the electrochemical performance of the battery. For example, when an inorganic hydrophobic material is used to coat the surface of an inorganic solid electrolyte, although it can reduce the water absorption of the inorganic solid electrolyte material to a certain extent, it usually forms a dense inorganic coating on the surface of the inorganic solid electrolyte, isolating the inorganic solid electrolyte from the outside world and making it unable to effectively transmit active ions such as lithium ions, thereby affecting the electrochemical performance of the coated electrolyte material.

[0026] Therefore, how to reduce the water absorption capacity of electrolyte materials while improving their electrochemical properties such as ionic conductivity remains a technical problem that needs to be solved urgently.

[0027] In view of this, an embodiment of the present invention provides an electrolyte material, such as Figure 1 As shown, the electrolyte material includes an inorganic solid electrolyte matrix and a porous coating layer present on the surface of the inorganic solid electrolyte matrix. The ratio of the specific surface area BET0 to the volume V0 of the electrolyte material is (0.6 to 12)*10 5 g -1 cm -1 , that is, the unit of specific surface area of ​​electrolyte material BET0 is cm 2 / g, the volume V0 of the electrolyte material is in cm 3 If 0.6*10 is satisfied 5 ≤BETs / Vs≤12*10 5 , that is, the surface area per unit mass volume of the electrolyte material satisfies (0.6~12)*10 5 range.

[0028] According to the inventor's research, by setting a porous coating layer on the surface of the inorganic solid electrolyte matrix (i.e., the inorganic solid electrolyte), and controlling the specific surface area and volume ratio of the electrolyte material to (0.6-12)*10 5 g -1 cm -1 Within the range of , the contact between the inorganic solid electrolyte matrix and water can be reduced based on the protective effect of the porous coating layer, thereby reducing the water absorption performance of the electrolyte material and reducing the moisture value (water content) of the electrolyte material. At the same time, the porous structure of the porous coating layer can provide a transmission channel for active ions such as lithium ions, thereby ensuring the electrochemical properties such as the ionic conductivity of the electrolyte material, and further achieving the low moisture property and high ionic conductivity property of the electrolyte material.

[0029] The reason for this analysis is that the specific surface area of ​​the electrolyte material is related to the number, size, and tortuosity of the pores in the porous coating layer, and the volume of the electrolyte material is related to the particle size of the electrolyte material. By synergistically regulating the specific surface area and volume of the electrolyte material so that the ratio thereof meets the above range, that is, when the total surface area per unit mass volume of the electrolyte material meets the above range, it is beneficial for the porous coating layer on the surface of the electrolyte material particles to have a pore structure with characteristics such as an appropriate number, size, and tortuosity. On the one hand, the porous coating layer can reduce the contact between the inorganic solid electrolyte matrix and water, thereby reducing the water absorption performance of the electrolyte material. On the other hand, the pore structure of the porous coating layer can provide a transmission channel for active ions such as lithium ions, thereby ensuring the electrochemical properties such as ionic conductivity of the electrolyte material. Therefore, the embodiment of the present invention can reduce the water absorption capacity of the solid electrolyte material and improve its electrochemical properties such as ionic conductivity. The electrolyte material can be used as a solid electrolyte in solid-state batteries, specifically in all-solid-state batteries or semi-solid-state batteries, to improve battery performance, specifically to improve the high-temperature cycle performance and room-temperature cycle performance of the battery.

[0030] In addition, the porous coating layer is coated on the surface of the inorganic solid electrolyte matrix in a film-like manner, which is also beneficial to improving the stability of the electrolyte material, and specifically can improve the thermal shrinkage performance of the electrolyte material.

[0031] For example, the ratio of the specific surface area BET0 to the volume V0 of the electrolyte material may be 0.6*10 5 g -1 cm -1 , 1*10 5 g -1 cm -1 , 1.5*10 5 g -1 cm -1 , 2*10 5 g -1 cm -1 , 2.5*10 5 g -1 cm -1 、3*10 5 g -1 cm -1 、3.5*10 5 g -1 cm -1 , 4*10 5 g -1 cm -1 , 4.5*10 5 g -1 cm -1 , 5*10 5 g -1 cm -1、5.5*10 5 g -1 cm -1 , 6*10 5 g -1 cm -1 、6.5*10 5 g -1 cm -1 , 7*10 5 g -1 cm -1 ,7.5*10 5 g -1 cm -1 ,8*10 5 g -1 cm -1 、8.5*10 5 g -1 cm -1 、9*10 5 g -1 cm -1 ,9.5*10 5 g -1 cm -1 , 10*10 5 g -1 cm -1 、10.5*10 5 g -1 cm -1 、11*10 5 g -1 cm -1 、11.5*10 5 g -1 cm -1 、12*10 5 g -1 cm -1 or a range consisting of any two of them.

[0032] In some preferred embodiments, the ratio of the specific surface area BET0 to the volume V0 of the electrolyte material is (3-10)*10 5 g -1 cm -1 , which is conducive to further taking into account both reducing the water absorption capacity of the electrolyte material and improving the electrochemical properties of the electrolyte material, such as the ionic conductivity.

[0033] Specifically, the electrolyte material is granular, and the specific shape can be spherical particles, square particles, irregular particles, etc., and its macroscopic appearance is powder. Among them, the inorganic solid electrolyte matrix is ​​also inorganic solid electrolyte particles, and the porous coating layer is coated on the surface of the inorganic solid electrolyte particles in a film shape. Under normal circumstances, the porous coating layer is basically evenly coated on the entire surface of the inorganic solid electrolyte particles.

[0034] In the embodiment of the present invention, the specific surface area and volume of the electrolyte material can be measured by conventional methods in the art. Specifically, the specific surface area of ​​the electrolyte material can be measured by the method specified in the national standard GB / T 8074; the volume V of the electrolyte material can be calculated from the radius R of the electrolyte material (calculated according to the spherical volume formula V=(4 / 3)πR3). The radius of the electrolyte material can be measured by a transmission electron microscope (TEM). In specific implementation, the diameters of at least 30 electrolyte material particles within the TEM test field can be measured, and then the average value of the at least 30 diameter measurements can be calculated. The average diameter value divided by 2 is the radius R of the electrolyte material, and then the volume of the electrolyte material can be calculated based on the radius R. When the electrolyte material is in the form of non-spherical particles (such as square, irregular, etc.), the volume of the electrolyte material can be calculated by its volume equivalent diameter. Specifically, the particle size (equivalent diameter) of the electrolyte material can be obtained by referring to the standard "GB / T 43196-2023". After conversion to radius, the volume V of the electrolyte material can be calculated by the sphere volume formula.

[0035] In the above-mentioned electrolyte material, the pore size of the porous coating layer can be nanoscale (i.e., its pore size is less than 1 μm). The nanoscale pore size is conducive to blocking moisture and reducing the water absorption performance of the electrolyte material. At the same time, it is conducive to providing channels for the transmission of active ions such as lithium ions, thereby improving the electrochemical properties of the electrolyte material such as ionic conductivity.

[0036] In some embodiments, the average pore size of the porous coating layer is 0.5 to 50 nm, for example, 0.5 nm, 0.8 nm, 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm or a range consisting of any two of them. In this way, the average pore size of the porous coating layer is not less than 0.5 nm, which is beneficial for further improving the electrolyte material's ability to transport ions while blocking moisture, thereby improving the ionic conductivity of the electrolyte material. At the same time, the average pore size of the porous coating layer is not higher than 50 nm, which is more conducive to blocking the contact between the inorganic solid electrolyte matrix and moisture through the porous coating layer, thereby further reducing the water absorption performance of the electrolyte material.

[0037] In the embodiment of the present invention, the average pore size of the porous coating layer can be measured by conventional methods, such as by the BET test method.

[0038] In some embodiments, the density of the porous coating layer may be 0.2 to 1.6 g / cm 3 , for example 0.2g / cm 3 , 0.3g / cm 3 , 0.4g / cm 3 , 0.5g / cm 3 , 0.8g / cm 3 , 1.0g / cm 3 , 1.2g / cm 3 , 1.22g / cm 3 , 1.25g / cm 3 , 1.28g / cm 3 , 1.3g / cm 3 , 1.35g / cm 3 , 1.37g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.55g / cm 3 , 1.6g / cm 3 or the range of any two of them, preferably 0.5 to 1.5 g / cm 3 , which is conducive to further taking into account both reducing the water absorption performance of the electrolyte material and improving the ionic conductivity of the electrolyte material. The reason for this is that density is the ratio of mass to volume. By synergistically regulating the mass and volume of the porous coating layer to meet the above-mentioned density range, the porous coating layer has a more suitable pore structure. While blocking the contact between the solid electrolyte matrix and water, it is more conducive to the transmission of active ions such as lithium ions, thereby improving the electrochemical properties of the electrolyte material, such as the ionic conductivity.

[0039] In an embodiment of the present invention, the density of the porous coating layer is the ratio of the mass of the porous coating layer to the volume of the porous coating layer. The mass of the porous coating layer can be obtained by weighing, and the particle diameter of the electrolyte material and the diameter of the inorganic solid electrolyte matrix are measured by TEM, and then converted into volume (the volume of the electrolyte material and the volume of the solid electrolyte matrix are converted respectively according to the spherical volume formula), and then the volume ratio of the porous coating layer is calculated to be ω (ω = volume of the porous coating layer / volume of the electrolyte material, volume of the porous coating layer = volume of the electrolyte material - volume of the solid electrolyte matrix).

[0040] In addition, the above-mentioned particle diameter can be characterized according to the method specified in GB / T 18907-2013 "Microbeam analysis electron microscopy transmission electron microscopy selected area electron diffraction analysis method".

[0041] In specific implementation, when testing the diameter of the electrolyte material and the diameter of the inorganic solid electrolyte matrix, the diameter of the electrolyte material particles and the diameter of the inorganic solid electrolyte matrix in the cross section can be tested by TEM. In specific implementation, the diameters of at least 30 electrolyte material particles and the diameter of the inorganic solid electrolyte matrix can be tested, and then the average value of the diameters of at least 30 electrolyte material particles measured is calculated, which is the particle diameter of the electrolyte material. The average value of the diameter measurement values ​​of the inorganic solid electrolyte matrix of at least 30 electrolyte material particles measured is calculated, which is the diameter of the inorganic solid electrolyte matrix (or average particle size).

[0042] In addition, the density ρ of the porous coating layer can be calculated by the following formula m :

[0043]

[0044] Wherein, M1 is the mass of the electrolyte material (i.e., the mass of the solid electrolyte after being coated by the porous coating layer); M0 is the mass of the inorganic solid electrolyte matrix; ρ is the true density of the electrolyte material, which can be characterized by the test method specified in the national standard GB-T 24203-2024 "Determination of bulk 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 this application, there is no particular restriction on the specific surface area of ​​the electrolyte material, and electrolyte materials with any specific surface area can be selected. Based on the consideration of the water absorption performance and lithium ion conductivity of the electrolyte material, the specific surface area of ​​the electrolyte material is preferably (5 to 60)*10 4 cm2 / g, for example 5cm2 / g, 10cm 2 / g, 15cm 2 / g, 20cm 2 / g, 25cm 2 / g, 30cm 2 / g、35cm 2 / g, 40cm 2 / g, 45cm 2 / g, 50cm2 / g, 55cm2 / g, 60cm2 / g or any two thereof, and more preferably the specific surface area of ​​the electrolyte material is (11 to 45)*10 4 cm 2 / g.

[0046] In some embodiments, the volume of the electrolyte material may be 0.3 to 0.5 cm 3 , for example 0.3cm 3 , 0.35cm 3 , 0.37cm3 、0.39cm 3 , 0.42cm 3 , 0.45cm 3 , 0.5cm 3 or a range consisting of any two of them.

[0047] In addition, the ratio of the thickness H of the porous coating layer to the average particle size D of the inorganic solid electrolyte matrix (H / D) can be less than or equal to 0.5, and H / D is, for example, 0.05, 0.1, 0.12, 0.13, 0.14, 0.15, 0.18, 0.2, 0.25, 0.3, 0.33, 0.35, 0.4, 0.45, 0.5 or a range consisting of any two of them, and H / D is preferably 0.05 to 0.3, which is more conducive to the function of the inorganic solid electrolyte matrix, and at the same time is conducive to the passage of active ions such as lithium ions through the porous coating layer, and further takes into account the reduction of the water absorption performance of the electrolyte material, thereby further improving the electrochemical properties such as the ionic conductivity of the electrolyte material.

[0048] In some embodiments, the average particle size D of the inorganic solid electrolyte matrix can be 100 to 2000 nm, for example, 100 nm, 500 nm, 800 nm, 820 nm, 850 nm, 860 nm, 900 nm, 950 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, 2000 nm or a range consisting of any two of them.

[0049] In addition, the particle size distribution of the solid electrolyte matrix can satisfy (D90-D10) / D50≤1.5. Here, D10 represents the particle size when the volume accumulation reaches 10% from the small particle size side in the particle size distribution of the solid electrolyte matrix material, D50 represents the particle size when the volume accumulation reaches 50% from the small particle size side in the particle size distribution of the solid electrolyte matrix material, and D90 represents the particle size when the volume accumulation reaches 90% from the small particle size side in the particle size distribution of the solid electrolyte matrix material.

[0050] In the embodiment of the present invention, the particle size D10, D50 and D90 of the solid electrolyte matrix can be measured by conventional methods in the art. For example, it can be tested by a laser force analyzer. Specifically, a laser scattering particle size analyzer (Malvern ZEN3690 particle size analyzer) can be used for characterization. The solid electrolyte matrix material particles are dispersed in pure water, and the D50, D90, and D10 of the solid electrolyte matrix material particles are measured. The inorganic solid electrolyte matrix in the electrolyte material can also be scanned by a scanning electron microscope (SEM), and the D50, D90, and D10 of the solid electrolyte matrix in the electrolyte material can be obtained by performing statistical analysis and calculation on the scanning results (such as analysis and calculation using Image J software).

[0051] In some embodiments, the thickness H of the porous coating layer can be 5 nm to 430 nm, for example, 5 nm, 10 nm, 30 nm, 50 nm, 80 nm, 100 nm, 120 nm, 125 nm, 135 nm, 140 nm, 150 nm, 200 nm, 230 nm, 260 nm, 300 nm, 350 nm, 400 nm, 430 nm or a range consisting of any two of them, preferably 120 to 300 nm, which is beneficial to further take into account the electrochemical properties such as reducing the water absorption performance of the electrolyte material and improving the ionic conductivity of the electrolyte material.

[0052] In an embodiment of the present invention, when testing the thickness of the porous coating layer, the thickness of the porous coating layer in the cross section can be tested by TEM. In specific implementation, the thickness of the porous coating layer of at least 30 electrolyte material particles can be tested, and then the average value of the at least 30 measured thickness values ​​is calculated, which is the thickness of the porous coating layer.

[0053] In some embodiments, the mass ratio of the porous coating layer to the electrolyte material can be 0.1% to 10%, for example, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0% or a range composed of any two of them, preferably 1% to 10%, which is beneficial to further take into account the reduction of the water absorption performance of the electrolyte material and the improvement of the electrochemical properties such as the ionic conductivity of the electrolyte material.

[0054] In addition, the above-mentioned porous coating layer includes a coating material, which may specifically include an inorganic oxide. The porous coating layer may be an inorganic porous coating layer mainly formed by an inorganic oxide. The inorganic oxide has good thermal stability and can further improve the heat shrinkage resistance of the electrolyte material, so that it exhibits better heat resistance in battery applications. At the same time, it is also beneficial to further improve the electrochemical stability and other properties between the electrolyte material and the battery electrode (such as the negative electrode), thereby further optimizing the battery performance.

[0055] In some embodiments, the inorganic oxide includes one or more of aluminum oxide, zirconium oxide, titanium dioxide, and silicon dioxide. By using at least one of these coating materials (inorganic oxides) to coat and modify the solid electrolyte matrix, it is more conducive to forming a porous coating layer with a suitable pore structure on the surface of the inorganic solid electrolyte matrix, blocking the inorganic solid electrolyte matrix from contact with water, while providing a transmission channel for active ions such as lithium ions, and facilitating a better bonding between the porous coating layer and the inorganic solid electrolyte matrix, so that the two are in closer contact, further avoiding problems such as the porous coating layer falling off, and these inorganic oxides have good thermal stability, thereby further improving the heat resistance and other properties of the electrolyte material, thereby further improving the comprehensive performance of the electrolyte material, and being more conducive to its application in solid-state batteries and optimizing battery performance.

[0056] In addition, the above-mentioned inorganic oxides and other coating materials can be nanoporous materials (porous nanoparticle materials). The surface of the inorganic solid electrolyte matrix is ​​modified by using nanoporous materials to form a porous coating layer, which can reduce the contact area between the inorganic solid electrolyte spines and water, and reduce the water absorption performance of the electrolyte material. At the same time, the nanoporous material can provide a transmission channel for active ions such as lithium ions, further improving the ion transmission performance of the electrolyte material during application.

[0057] In addition, the electrolyte material may further contain a first group, wherein the first group includes one or more of a vinyl group, an epoxy group, and an amino group. The first group may be present in the porous coating layer of the electrolyte material, specifically, the outer surface of the porous coating layer and / or in at least a portion of the pores of the porous coating layer.

[0058] 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 (for example, groups such as epoxy groups can react with the functional groups of active components in materials such as electrolytes during the charge and discharge process of the battery), forming more stable chemical bonds and other groups, thereby further improving battery performance. For example, when the electrolyte 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, making the diaphragm containing the above-mentioned electrolyte material and the electrode (such as the positive electrode and / or the negative electrode) more tightly bonded, thereby helping to reduce the interfacial impedance between the diaphragm and the electrode and improving the performance of the battery.

[0059] In some embodiments, the molar content of the first group in the electrolyte material may be 0.1% to 5%, for example, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or any two thereof.

[0060] In an embodiment of the present invention, the molar content of the first group (functional group) in the porous coating layer can be measured by infrared spectroscopy (FTIR). In specific implementation, the electrolyte material can be subjected to infrared spectroscopy to measure the infrared spectrum of the electrolyte material. The molar content of the first group in the electrolyte 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.

[0061] In some embodiments, the inorganic solid electrolyte matrix may include one or more of lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), lithium lanthanum titanium oxide (LLTO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum zirconium oxide (LLZO), and element-doped modified derivatives of the foregoing inorganic solid electrolytes. The doping element in the element-doped modified derivative 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.

[0062] In the embodiments of the present invention, the inorganic solid electrolyte matrix and other materials used can be obtained by conventional methods for obtaining these materials, such as commercial purchase or self-preparation by conventional methods in the field. The particle size and particle size distribution and other characteristics of the inorganic solid electrolyte matrix can be regulated by conventional methods, and there is no special limitation on this.

[0063] An embodiment of the present invention also provides a method for preparing the above-mentioned electrolyte material, comprising the following steps: subjecting a mixed solution containing an inorganic solid electrolyte matrix, a pore-forming agent, a coating material precursor and a first solvent to a sol-gel reaction to form a coating film layer on the surface of the inorganic solid electrolyte matrix to obtain an electrolyte precursor; and sintering the electrolyte precursor to form a porous coating layer on the surface of the inorganic solid electrolyte matrix to obtain an electrolyte material.

[0064] Through the preparation process of the above-mentioned electrolyte material, the inorganic solid electrolyte matrix is ​​surface-coated and modified with a coating material to form a porous coating layer (a continuous porous coating layer (or shell layer)), and the electrolyte material is obtained. While reducing the water absorption performance of the obtained electrolyte material, the pore structure of the porous coating layer can provide a channel for the transmission of active ions such as lithium ions, thereby improving the ion transmission capacity of the electrolyte material, and at the same time, it is also beneficial to improve the close bonding between the porous coating layer and the inorganic solid electrolyte matrix, further avoiding the problem of the porous coating layer falling off, thereby further improving the stability and electrochemical performance of the electrolyte material. The electrolyte material obtained by the above-mentioned preparation process has a strong bonding force between its porous coating layer and the inorganic solid electrolyte matrix, and has a porous structure, which can not only allow active ions such as lithium ions to be smoothly transmitted through the porous coating layer, but also can isolate the inorganic solid electrolyte matrix from moisture, reduce the moisture value of the electrolyte material, and improve the performance of the electrolyte material.

[0065] During the aforementioned preparation process, the pore-forming agent provides adhesion to the coating material and volatilizes to form pores during the electrolyte precursor sintering process. It can include one or more organic materials such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acid, starch, nanocellulose, and polyethylene glycol. During the sintering process, the pore-forming agent and other organic components are typically sintered away, forming an inorganic porous coating layer primarily composed of inorganic oxides on the surface of the inorganic solid electrolyte matrix.

[0066] Specifically, the coating material is the main material used to form the porous coating layer, which can be a porous coating material synthesized by hydrolysis of a coating material precursor. Specifically, as mentioned above, the coating material of the porous coating layer may include an inorganic oxide, specifically one or more of alumina, zirconia, titanium dioxide, silicon dioxide, etc. The coating material precursor may include an inorganic oxide precursor, and the inorganic oxide precursor may include, for example, ethyl orthosilicate and / or tetraethyl titanate, but is not limited to this. The embodiment of the present invention may adopt a conventional inorganic oxide precursor material that can synthesize the corresponding inorganic oxide material.

[0067] For example, the coating material in the formed porous coating layer includes silicon dioxide, and the coating material precursor may include tetraethyl orthosilicate. During the sol-gel reaction, tetraethyl orthosilicate forms silica sol through hydrolysis, and then forms silicon dioxide during the subsequent sintering process, thereby forming a continuous porous coating layer (i.e., an inorganic silicon dioxide porous coating layer) on the surface of the inorganic solid electrolyte matrix. When tetraethyl titanate is used, the inorganic oxide formed is titanium dioxide.

[0068] In addition, based on the total mass of the inorganic solid electrolyte matrix, the pore former and the coating material precursor, the mass proportion of the inorganic solid electrolyte matrix can be 55% to 85%, for example, 55%, 57%, 60%, 63%, 64%, 65%, 67%, 70%, 75%, 78%, 80%, 82%, 85% or a range consisting of any two thereof, the mass proportion of the pore former can be 10% to 20%, for example, 10%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% or a range consisting of any two thereof, and the mass proportion of the coating material precursor can be 5% to 35%, for example, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 32%, 35% or a range consisting of any two thereof.

[0069] In some embodiments, the mass ratio of the coating material precursor to the inorganic solid electrolyte matrix is ​​0.1 to 0.55, for example, 0.1, 0.2, 0.25, 0.28, 0.3, 0.35, 0.4, 0.43, 0.45, 0.5, 0.53, 0.55 or a range consisting of any two thereof.

[0070] In some embodiments, the mass ratio of the porogen to the coating material precursor can be 0.35 to 1.7, for example, 0.35, 0.38, 0.42, 0.45, 0.5, 0.53, 0.56, 0.6, 0.65, 0.7, 0.9, 1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or any two thereof.

[0071] In some embodiments, the mass ratio of the inorganic solid electrolyte matrix to the pore former is 1:(0.05-0.4), for example, 1:0.05, 1:0.1, 1:0.15, 1:0.17, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4 or a range consisting of any two of them, which is conducive to the formation of a porous coating layer with a more suitable pore structure, further taking into account the reduction of the water absorption capacity of the prepared electrolyte material and the improvement of the ionic conductivity of the electrolyte material and other properties.

[0072] Specifically, the mixed solution is alkaline, and its pH can be specifically 8 to 9, which is more conducive to the hydrolysis of the coating material precursor and the formation of a coating film layer on the surface of the inorganic solid electrolyte through a sol-gel reaction, and then a porous coating layer is formed through sintering treatment.

[0073] In some embodiments, the preparation process of the mixed liquid may include: mixing the inorganic solid electrolyte matrix and the first solvent, stirring for 1h to 6h, for example, 1h, 2h, 3h, 4h, 5h, 6h or a range of any two thereof, and then adding a pore former and a coating material precursor thereto, adjusting the pH to 8 to 9, and obtaining a mixed liquid.

[0074] During specific implementation, ammonia water or organic amine may be used to adjust the pH of the mixed solution, and the organic amine may include triethylamine.

[0075] Specifically, the first solvent may include an organic solvent, specifically one or more of an alcohol solvent, tetrahydrofuran, ethyl acetate, etc. The alcohol solvent may include one or more of ethanol, methanol, etc. In specific implementation, anhydrous ethanol may be used.

[0076] In some embodiments, the sol-gel reaction time may be 1 h to 6 h, for example, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, or any combination thereof.

[0077] In addition, the sol-gel reaction can be carried out at room temperature and under stirring.

[0078] In some specific embodiments, the sol-gel reaction process includes stirring the mixture for 1 h to 6 h, for example, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h or a range consisting of any two thereof, to obtain an electrolyte precursor.

[0079] In a specific implementation, the inorganic solid electrolyte matrix can be dispersed in a first solvent and stirred and dispersed for 1 hour to 6 hours, and then polyvinyl alcohol and a coating material precursor are added thereto, and the pH is adjusted to 8 to 9 (i.e., a mixed solution is obtained), and then stirred and dispersed for 1 hour to 6 hours to carry out a sol-gel reaction, and then the solvent is removed by rotary evaporation or the like to obtain an electrolyte precursor; the electrolyte precursor is then sintered to obtain an electrolyte material.

[0080] In addition, the sintering treatment temperature can be 700-1200°C, for example, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C or a range consisting of any two thereof, and the sintering treatment time can be 3h-7h, for example, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h or 7h or a range consisting of any two thereof.

[0081] In some embodiments, the method for preparing the electrolyte material further comprises the step of modifying the porous coating layer with a silane coupling agent, i.e., after sintering, modifying the resulting sintered product with a silane coupling agent to produce the electrolyte material. After the sintering, the resulting sintered product is surface-modified with a silane coupling agent, i.e., the sintered product is contacted and reacted with the silane coupling agent to modify the porous coating layer. The surface modification of the porous coating layer with the silane coupling agent forms first groups on the outer surface and in at least a portion of the pores of the porous coating layer, thereby further improving the performance of the resulting electrolyte material.

[0082] Specifically, the silane coupling agent may include one or more of diethylenetriaminopropyltrimethoxysilane, triethoxyvinylsilane, vinyltrimethoxysilane, aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane (KH560), γ-methacryloxypropyltrimethoxysilane (KH570), N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, (3-aminopropyl)triethoxysilane (KH550), (3-aminopropyl)trimethoxysilane (KH540), 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-aminopropyl(diethoxy)methylsilane, and 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane, which is beneficial to introduce organic groups such as the first group of a suitable type into the electrolyte material, thereby further improving the performance of the electrolyte material.

[0083] However, the types of silane coupling agents used in the embodiments of the present invention are not limited to the coupling agents described above.

[0084] 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.

[0085] Specifically, the temperature for modifying the sintered product using a silane coupling agent can be 30 to 60° C., for example, 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C. or a range consisting of any two thereof, and the time for the modification treatment can be 2 to 12 h, for example, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h or a range consisting of any two thereof.

[0086] In addition, the process of modifying the sintered product using a silane coupling agent can be carried out at a pH of 4 to 9, such as 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9 or any two thereof.

[0087] In addition, the process of modifying the sintered product with a silane coupling agent can be carried out in the presence of a second solvent.

[0088] In some specific embodiments, the process of modifying the sintered product using a silane coupling agent may include: mixing the sintered product with a second solvent, adjusting the pH of the system to 4 to 9, then adding the silane coupling agent thereto, and performing a modification treatment at 30 to 60° C. for 2 to 12 hours to obtain an electrolyte material.

[0089] In a specific implementation, the sintered product can be dispersed in a second solvent, and the solid content of the resulting mixed liquid is between 10 and 50%. The pH value of the system is then adjusted between 4 and 9, and a silane coupling agent is added thereto. The system temperature is maintained between 30 and 60°C, stirred for 2 to 12 hours, and the solvent is removed by filtration or the like. The obtained solid product is dried, for example, by vacuum freeze drying, to obtain the final electrolyte material.

[0090] Specifically, the second solvent may include an organic solvent, specifically anhydrous ethanol, tetrahydrofuran, ethyl acetate, methanol, etc. During implementation, anhydrous ethanol may be used.

[0091] In some embodiments, the amount of the silane coupling agent is such that the mass ratio of the sintered product to the silane coupling agent is 99:1 to 93:7, for example, 99:1, 98:2, 97:3, 94:6, 95:5, 94:6, 93:7 or any two thereof.

[0092] An embodiment of the present invention further provides a separator comprising a base membrane and an electrolyte layer (solid electrolyte layer) present on at least one surface of the base membrane, wherein the electrolyte layer comprises the aforementioned electrolyte material or an electrolyte material prepared according to the aforementioned electrolyte material preparation method. This separator has advantages corresponding to those of the aforementioned electrolyte material, which will not be further described.

[0093] In an embodiment of the present invention, the moisture value of the diaphragm may be less than or equal to 700 ppm, for example, less than or equal to 650 ppm, or less than or equal to 630 ppm, or less than or equal to 600 ppm, or less than or equal to 580 ppm, or less than or equal to 560 ppm, or less than or equal to 550 ppm, or less than or equal to 520 ppm, or less than or less than 500 ppm. It has low moisture properties, which is beneficial to improving battery performance.

[0094] In some specific embodiments, the moisture value of the diaphragm is 400ppm to 700ppm, for example, 400ppm, 410ppm, 430ppm, 450ppm, 480ppm, 500ppm, 520ppm, 550ppm, 580ppm, 600ppm, 630ppm, 640ppm, 650ppm, 680ppm, 700ppm or a range consisting of any two thereof.

[0095] 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".

[0096] Specifically, the electrolyte layer can be provided on one side of the base membrane, or the electrolyte layer can be provided on both the front and back surfaces of the base membrane. When the electrolyte layer is provided on one side of the base membrane, when the diaphragm is used in the battery, the side of the diaphragm provided with the electrolyte layer can face the positive electrode sheet or 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.

[0097] The diaphragm (or solid electrolyte membrane) 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.

[0098] In some embodiments, the thickness of the 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.

[0099] In an embodiment of the present invention, the thickness of the electrolyte layer refers to the thickness of the electrolyte layer on one side of the diaphragm. For example, when electrolyte layers are provided on both the front and back surfaces of the base membrane, the thickness of the electrolyte layer refers to the thickness of the electrolyte layer on either side of the base membrane.

[0100] 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.

[0101] 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.

[0102] In some embodiments, the base film may include one or more of a polyethylene porous film, a polypropylene porous film, a polyimide porous film, a polyvinylidene fluoride porous film, and a polyethylene terephthalate (PET) porous film.

[0103] In embodiments of the present invention, an electrolyte layer can be formed on the surface of a base film by coating. Specifically, an electrolyte slurry for forming the electrolyte layer can be applied to the surface of the base film by a micro-gravure reverse coating process to form the electrolyte layer, thereby producing 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 aforementioned electrolyte material.

[0104] In some embodiments, the electrolyte slurry is coated on the surface of the base membrane and then dried at 50-100° C. to form an electrolyte layer on the surface of the base membrane to produce a separator.

[0105] In the separator of the embodiment of the present invention, the electrolyte layer may further include one or more additives such as an adhesive (binder), a dispersant, a wetting agent, and a thickener. Specifically, in the electrolyte slurry used to form the electrolyte layer, the binder is added to improve adhesion; in the electrolyte slurry used to form the electrolyte layer, the dispersant is added to improve dispersibility and coating properties; in the electrolyte slurry used to form the electrolyte layer, the thickener is added to improve storage stability; and in the electrolyte slurry used to form the electrolyte layer, the wetting agent is added to improve coating uniformity.

[0106] The present invention does not particularly limit the adhesive in the electrolyte layer. For example, the adhesive 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.

[0107] The present invention does not impose any particular limitation on the weight percentage of the binder in the electrolyte layer, and the amount added 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] The present invention does not impose any particular restrictions on the weight percentage of additives such as dispersants, thickeners, and wetting agents, and the amount of additives can be freely selected to suit the purpose. For example, the weight percentage of each additive in the electrolyte layer (i.e., the weight percentage of the additive in the electrolyte layer) is 0.1 wt% to 3 wt%.

[0112] For example, the mass percentage of the dispersant in the electrolyte layer may be 0.1 wt% to 3 wt%; the mass percentage of the thickener in the electrolyte layer may be 0.1 wt% to 3 wt%; and the mass percentage of the wetting agent in the electrolyte layer may be 0.1 wt% to 3 wt%.

[0113] An embodiment of the present invention further provides a battery including the above-mentioned separator. The battery has advantages corresponding to the above-mentioned electrolyte material, which will not be described in detail.

[0114] Specifically, the above-mentioned battery may be a semi-solid-state battery or a fully solid-state battery.

[0115] 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.

[0116] 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.

[0117] 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).

[0118] 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.

[0119] When the positive electrode coating further includes a solid electrolyte, the solid electrolyte in the positive electrode coating and the electrolyte material in the separator may be the same as or different from each other.

[0120] 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%.

[0121] 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.

[0122] In the embodiments of the present invention, the positive electrode sheet can be produced by conventional coating methods in the art. Specifically, the components used to form the positive electrode coating, such as the positive electrode active material, solid electrolyte, conductive agent, and binder, can be dispersed in a third solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry. The positive electrode slurry is then applied to the surface of the positive electrode current collector and subjected to drying, roll pressing, and other processes to produce the positive electrode sheet. The coating, drying, and roll pressing processes involved are conventional operations for preparing positive electrode sheets using a coating method and are not particularly limited thereto.

[0123] 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.

[0124] Specifically, the negative electrode coating (negative electrode active material layer) may include materials such as a negative electrode active material, a conductive agent and a binder. These materials may be conventional materials in the art. 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 fibers; 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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 specific surface area and volume of the electrolyte material, the density and thickness of the porous coating layer, and the type and content of the first group are referred to above and will not be repeated in detail; the mass ratio of the porous coating layer to the electrolyte material = (mass of the electrolyte material - mass of the inorganic solid electrolyte matrix) / mass of the electrolyte material.

[0130] Example 1

[0131] 1. Preparation of positive electrode

[0132] Lithium cobalt oxide (Xiamen Xiatung New Energy Materials Co., Ltd., model L501B), acetylene black (Hexing Chemical, model: Li-H 140) and PVDF (Arkema, model HSV900) were mixed in a mass ratio of 90:5:5 and added to NMP to prepare a positive electrode slurry;

[0133] 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.

[0134] 2. Preparation of negative electrode sheet

[0135] Artificial graphite (B&T New Materials Group Co., Ltd., model: BFC-K), acetylene black (Hexing Chemical, model: Li-H 140), and SBR emulsion (Zeiong Co., Ltd., model: BM-451B) were mixed and added to deionized water to prepare the negative electrode slurry; wherein the mass ratio of artificial graphite, acetylene black, and SBR was 90:5:5;

[0136] 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.

[0137] 3. Preparation of electrolyte materials

[0138] S1. The solid electrolyte matrix (LATP) was dispersed in anhydrous ethanol and stirred for 3 h. Then, polyvinyl alcohol and tetraethyl orthosilicate (Nanjing Liansi Chemical Co., Ltd., model USi-6042) were added thereto. The pH value of the system was adjusted to 8.5 with ammonia water. Then, the mixture was stirred and dispersed for 3 h (for sol-gel reaction). The solvent was then removed by rotary evaporation to obtain an electrolyte precursor.

[0139] S2. Sintering the electrolyte precursor at 800° C. for 6 h to obtain an electrolyte material.

[0140] 4. Preparation of diaphragm

[0141] The electrolyte material is dispersed in pure water, and then a dispersant, a thickener, a binder, and a wetting agent are gradually added and stirred thoroughly to prepare an electrolyte slurry; wherein, the mass ratio of the electrolyte material, the dispersant, the thickener, the binder, and the wetting agent is 91:1.5:7:0.5, the dispersant is a modified polyamide polymer (Kimet KMT-3604, Foshan Corning New Materials Co., Ltd.), the binder is a polyacrylate binder (LIS-S104, Shanghai Sanrui Polymer Materials Co., Ltd.), the thickener is sodium carboxymethyl cellulose (BH90-Ⅱ, Changshu Weiyi Technology Co., Ltd.), and the wetting agent is a polyether-modified silicone polymer (Kimet KMT-5514, Foshan Corning New Materials Co., Ltd.);

[0142] 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 an electrolyte layer on the surface of the base membrane; wherein the base membrane is made of a polyethylene diaphragm (polyethylene porous membrane), the thickness of the base membrane is 9μm, the porosity of the base membrane is 38%, and the thickness of the electrolyte layer is 2μm.

[0143] 5. Preparation of batteries

[0144] The positive electrode sheets, separators and negative electrode sheets are stacked alternately to assemble into a laminated battery cell, which is then encapsulated in an aluminum-plastic film shell. After processes such as liquid injection and formation, a semi-solid-state battery is produced.

[0145] The side of the separator provided with the electrolyte layer faces the positive electrode sheet.

[0146] Among them, the electrolyte is composed of solvent components (EC, DEC, EMC), LiPF6, semi-solid battery crosslinking agent polyethylene glycol diacrylate and azobisisobutyronitrile. The concentration of LiPF6 in the electrolyte is 1 mol / L, the volume ratio of EC, DEC, and EMC is 1:1:1, the mass of polyethylene glycol diacrylate accounts for 10% of the total mass of the electrolyte, and the mass of azobisisobutyronitrile is 2% of the mass of polyethylene glycol diacrylate.

[0147] Examples 2 to 16, Comparative Examples 1 to 2: The difference from Example 1 is that the electrolyte materials and their preparation methods are different. The remaining steps and conditions are the same as Example 1. The differences in the electrolyte materials are shown in Tables 1, 2, and 3. The preparation methods of the electrolyte materials of Examples 2 to 16 and Comparative Examples 1 and 2 are as follows.

[0148] The preparation methods of the electrolyte materials in Examples 2 to 10 and Comparative Examples 1 to 2 are basically the same as those in Example 1, except that the mass ratios of the inorganic solid electrolyte matrix (LATP), the coating material precursor (ethyl orthosilicate) and the polyvinyl alcohol are different, as shown in Tables 1, 2 and 3.

[0149] The difference between Example 11 and Example 1 is that the electrolyte material of Example 11 contains a first group, and the difference between the preparation process of the electrolyte material of Example 11 and Example 1 is that after sintering in step S2, the sintered product is modified using a silane coupling agent KH540, that is, the sintered product is dispersed in anhydrous ethanol, the pH of the system is adjusted to 8.0, and then the silane coupling agent KH540 is added thereto (the mass ratio of the sintered product to KH540 is 99:1), the reaction is carried out at 45°C for 4h, and then filtered, and the obtained solid product is dried to obtain the electrolyte material.

[0150] The preparation methods of the electrolyte materials in Examples 12 to 14 are basically the same as those in Example 11, except that the mass ratios of the sintered product and the silane coupling agent KH540 are different, as shown in Tables 1, 2 and 3.

[0151] The preparation method of the electrolyte material in Example 15 is basically the same as that in Example 12, except that the silane coupling agent used is KH570, as shown in Table 1, Table 2 and Table 3.

[0152] The preparation method of the electrolyte material in Example 16 is basically the same as that in Example 11, except that the coating material in the porous coating layer is titanium dioxide, the coating material precursor is tetraethyl titanate, the mass ratio of LATP, tetraethyl titanate, and polyvinyl alcohol is 61.7:23.3:15, the silane coupling agent used is KH560, and the mass ratio of the sintered product to the silane coupling agent is 97:3. See Tables 1, 2, and 3 for details.

[0153] The specific surface area BET0 of the electrolyte material, the volume V0 of the electrolyte material, the ratio of the specific surface area BET0 of the electrolyte material to the volume V0 (BET0 / V0), the density of the porous coating layer, the thickness H of the porous coating layer, the ratio of the thickness H of the porous coating layer to the average particle size D of the inorganic solid electrolyte (H / D), the average pore size of the porous coating layer, the mass ratio of the porous coating layer to the electrolyte material, the type of the coating material (inorganic oxide) of the porous coating layer, the type and molar content of the first group in the electrolyte material, the coating material precursor, the raw material ratio when preparing the electrolyte material (the mass ratio of the inorganic solid electrolyte matrix, the coating material precursor, and the pore former), the type of silane coupling agent, and the mass ratio of the sintered product to the silane coupling agent are summarized in Tables 1, 2, and 3.

[0154] The following performance tests were performed on the solid electrolytes / batteries of the embodiments and comparative examples, and the results are shown in Table 3.

[0155] 1. Test of diaphragm moisture value

[0156] 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".

[0157] 2. Capacity retention test of battery after 500 cycles at 45°C

[0158] 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.

[0159] 3. Battery 1500 cycles 1C battery cycle performance test

[0160] 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 25°C, the charge and discharge rate was 1C, and the number of cycles was 1500. The capacity retention rate (the ratio of the battery's capacity after 1500 cycles to the initial capacity) after 1500 cycles at 25°C is shown in Table 3.

[0161] Table 1

[0162]

[0163] Table 2

[0164]

[0165] Table 3

[0166]

[0167]

[0168] As can be seen from Table 3, compared with Comparative Examples 1 and 2, in Examples 1 to 16, a porous coating layer is provided on the surface of the inorganic solid electrolyte matrix in the electrolyte material, and the ratio of the specific surface area to the volume of the resin of the electrolyte material is controlled to be (0.6 to 12)*10 5 g -1 cm -1 Within the range of , the water absorption capacity of the electrolyte material can be reduced, and the electrochemical properties such as the ionic conductivity of the electrolyte material can be improved, the moisture value of the diaphragm can be reduced, and the high-temperature cycle performance and room-temperature cycle performance of the battery can be improved.

[0169] In addition, it can be seen from Table 4 that when the density of the porous coating layer is between 0.5 and 1.5 g / cm 3 When the moisture content of the separator is within the range of 100%, the moisture content of the separator is further reduced, thereby improving the high-temperature cycle performance and room-temperature cycle performance of the battery. For example, compared with Examples 5 and 6, the separator of Example 2 has a lower moisture content, and the battery has a higher high-temperature cycle capacity retention rate and room-temperature long cycle capacity retention rate.

[0170] Furthermore, Table 4 shows that when the ratio of the thickness H of the porous coating layer to the average particle size D of the inorganic solid electrolyte matrix is ​​less than or equal to 0.5, the high-temperature and room-temperature cycling performance of the battery can be further improved while maintaining a low moisture content in the separator. For example, compared to Example 7, Examples 1 and 8 to 10 can further improve the battery's high-temperature cycling capacity retention rate and room-temperature long-cycle capacity retention rate.

[0171] Furthermore, Table 4 shows that the introduction of the first group into the electrolyte material improves the battery's cycling performance. When the molar content of the first group in the electrolyte material is within the range of 0.1% to 5%, it further reduces the separator's moisture content, enhancing both the battery's high-temperature cycling performance and its room-temperature cycling performance. For example, compared to Example 14, Examples 11 to 13 can further reduce the separator's moisture content and improve the battery's high-temperature cycling capacity retention and room-temperature long-cycle capacity retention.

[0172] In addition, based on Example 1, by regulating the ratio of the inorganic solid electrolyte, the coating material precursor and the pore-forming agent and other conditions, the average pore size of the porous coating layer in the prepared electrolyte material can be regulated. For example, when the average pore size of the porous coating layer is regulated to about 0.5 nm, 15 nm, 30 nm and 50 nm respectively, the electrochemical properties such as the water absorption performance and ionic conductivity of the electrolyte can be balanced. While reducing the moisture content of the diaphragm, the cycle performance of the battery is improved (the moisture content of the diaphragm is lower than that of the diaphragm in Comparative Example 1 and Comparative Example 2, and the capacity retention rate of the battery after 500 cycles at 45 ° C and the capacity retention rate after 1500 cycles at 1C are better than those of the batteries in Comparative Example 1 and Comparative Example 2). I will not elaborate on this. The study found that when the ratio of the specific surface area to volume of the electrolyte material is (0.6 to 12)*10 5 g -1 cm -1 On this basis, when the pore size of the porous coating layer is in the range of 0.5 to 50 nm, it is more conducive to taking into account both reducing the water absorption performance of the electrolyte material and improving the electrochemical properties such as the ion conductivity of the electrolyte material, thereby further improving the cycle performance of the battery.

[0173] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. An electrolyte material, characterized in that The invention comprises an inorganic solid electrolyte matrix and a porous coating layer on the surface of the inorganic solid electrolyte matrix, wherein the ratio of the specific surface area to the volume of the electrolyte material is (0.6 to 12)*10 5 g -1 cm -1 .

2. The electrolyte material according to claim 1, characterized in that The density of the porous coating layer is 0.5 to 1.5 g / cm 3 .

3. The electrolyte material according to claim 1 or 2, characterized in that The ratio of the specific surface area to the volume of the electrolyte material is (3 to 10)*10 5 g -1 cm -1 ; And / or, the specific surface area of ​​the electrolyte material is (5-60)*10 4 cm 2 / g, preferably (11 to 45)*10 4 cm 2 / g.

4. The electrolyte material according to any one of claims 1 to 3, characterized in that The ratio of the thickness of the porous coating layer to the average particle size of the inorganic solid electrolyte matrix is ​​less than or equal to 0.5, preferably 0.05 to 0.3; and / or, the thickness of the porous coating layer is 5 to 430 nm, preferably 120 to 300 nm; And / or, the average particle size of the inorganic solid electrolyte matrix is ​​100 to 2000 nm.

5. The electrolyte material according to any one of claims 1 to 4, characterized in that The mass ratio of the porous coating layer to the electrolyte material is 0.1% to 10%, preferably 1% to 10%.

6. The electrolyte material according to any one of claims 1 to 5, characterized in that The average pore diameter of the porous coating layer is 0.5 to 50 nm.

7. The electrolyte material according to any one of claims 1 to 6, characterized in that The porous coating layer includes an inorganic oxide, and preferably the inorganic oxide includes one or more of alumina, zirconia, titania, and silica.

8. The electrolyte material according to any one of claims 1 to 7, characterized in that The electrolyte material contains a first group, wherein the first group includes one or more of a vinyl group, an epoxy group, and an amino group; Preferably, the molar content of the first group in the electrolyte material is 0.1% to 5%.

9. A method for preparing the electrolyte material according to any one of claims 1 to 8, characterized in that: The following steps are involved: subjecting a mixed solution containing an inorganic solid electrolyte matrix, a pore-forming agent, a coating material precursor, and a first solvent to a sol-gel reaction to form a coating film layer on the surface of the inorganic solid electrolyte matrix to obtain an electrolyte precursor; The electrolyte precursor is sintered to form the porous coating layer from the coating film layer on the surface of the inorganic solid electrolyte matrix, thereby obtaining the electrolyte material.

10. The method for preparing the electrolyte material according to claim 9, characterized in that: The pore-forming agent includes one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acid, starch, nanocellulose, and polyethylene glycol; And / or, based on the total mass of the inorganic solid electrolyte matrix, the pore former and the coating material precursor, the mass of the inorganic solid electrolyte matrix accounts for 55% to 85%, the mass of the pore former accounts for 10% to 20%, and the mass of the coating material precursor accounts for 5% to 35%; And / or, the coating material precursor includes an inorganic oxide precursor; preferably, the inorganic oxide precursor includes tetraethyl orthosilicate and / or tetraethyl titanate; And / or, the mixed solution is alkaline, preferably, the pH of the mixed solution is 8 to 9; And / or, the sol-gel reaction time is 1 to 6 hours.

11. The method for preparing an electrolyte material according to claim 9 or 10, characterized in that: The sintering process is carried out at a temperature of 700 to 1200° C. and for a time of 3 to 7 hours.

12. The method for preparing an electrolyte material according to any one of claims 9 to 11, characterized in that: Also includes: After the sintering treatment, the obtained sintered product is modified with a silane coupling agent to obtain the electrolyte material; Preferably, the mass ratio of the sintered product to the silane coupling agent is 99:1 to 93:7; Preferably, the temperature of the modification treatment is 30-60°C and the time is 2-12 hours; Preferably, the process of modifying the obtained sintered product with a silane coupling agent comprises: after the sintering treatment, mixing the obtained sintered product with a second solvent, adjusting the pH of the system to 4 to 9, then adding the silane coupling agent thereto, and performing a modification treatment at 30 to 60° C. for 2 to 12 hours to obtain the electrolyte material; 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.

13. A diaphragm, characterized in that: The invention comprises a base film and an electrolyte layer present on at least one surface of the base film, wherein the electrolyte layer comprises the electrolyte material according to any one of claims 1 to 8 or the electrolyte material prepared according to the preparation method of the electrolyte material according to any one of claims 9 to 12.

14. A battery, characterized in that: The diaphragm according to claim 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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