Composite electrolyte membrane, preparation method thereof and all-solid-state battery

Abstract

The invention relates to the technical field of all-solid-state batteries, in particular to a composite electrolyte membrane, a preparation method thereof and an all-solid-state battery. The composite electrolyte membrane comprises a halide layer, a sulfide layer and a polymer silver layer which are sequentially stacked. The material of the halide layer comprises chloride electrolyte and / or bromide electrolyte; the material of the sulfide layer comprises sulfide electrolyte; the materials of the polymer silver layer comprise polymer electrolyte and nano-silver. Wherein the halide layer can be in contact with a positive electrode to resist oxidation, so that the oxidation resistance of the composite electrolyte membrane is improved; the sulfide layer can improve the ionic conductivity; nano-silver in the polymer silver layer can form a silver-lithium alloy, so that growth of lithium dendrites is avoided, and the cycle performance of the composite electrolyte membrane and the cycle performance of the battery prepared from the composite electrolyte membrane are improved; therefore, the composite electrolyte membrane is excellent in comprehensive performance and suitable for large-scale application.

Description

Technical Field

[0001] The present invention relates to the technical field of all-solid-state batteries, and in particular to a composite electrolyte membrane and a preparation method thereof, and an all-solid-state battery. Background Art

[0002] As the energy density of lithium-ion batteries continues to increase, their safety is becoming increasingly less so. Compared to liquid and semi-solid batteries, all-solid-state batteries eliminate the risk of leakage due to the lack of liquid. They also offer greater thermal stability and a wider operating temperature range. Solid-state battery technology will significantly improve safety.

[0003] The electrolyte membrane in solid-state batteries is one of the most important components. Based on the characteristics of the electrolyte materials, it can be mainly divided into the following types, each with its own disadvantages: (1) Polymer system, disadvantages: low ionic conductivity at room temperature and narrow electrochemical window, which limits the power output and application range of the battery. (2) Oxide system, disadvantages: low ionic conductivity and poor interface contact, which will affect the battery's charge and discharge performance and energy conversion efficiency. (3) Sulfide system, disadvantages: contact with air will form toxic hydrogen sulfide, requiring strict control of the production environment and process to ensure product quality and safety, which increases the difficulty and cost of production. (4) Halide system, disadvantages: the reduction potential of the halide system is not low enough to match the metal lithium negative electrode, and the raw material cost is too high, which limits its widespread application in solid-state batteries.

[0004] Therefore, it is of great significance to provide an all-solid-state battery electrolyte membrane with excellent comprehensive performance.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The first object of the present invention is to provide a composite electrolyte membrane, wherein the halide layer can be in contact with the positive electrode to resist oxidation, thereby improving the oxidation resistance of the composite electrolyte membrane, increasing the charge and discharge voltage of the battery, and thus improving the energy density of the battery; the sulfide layer can improve the ionic conductivity; the nanosilver in the polymer silver layer can form a silver-lithium alloy, avoid the growth of lithium dendrites, and improve the cycle performance of the composite electrolyte membrane and the battery prepared therefrom; therefore, the composite electrolyte membrane has excellent comprehensive performance and is suitable for large-scale application.

[0007] The second object of the present invention is to provide a method for preparing a composite electrolyte membrane, which has simple operation, short process and is easy to achieve batch production.

[0008] The third object of the present invention is to provide an all-solid-state battery having good safety performance, high charge and discharge performance and energy conversion efficiency, and excellent cycle performance.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted: The present invention first provides a composite electrolyte membrane, comprising a halide layer, a sulfide layer and a polymer silver layer stacked in sequence; the material of the halide layer comprises a chloride electrolyte and / or a bromide electrolyte; the material of the sulfide layer comprises a sulfide electrolyte; and the material of the polymer silver layer comprises a polymer electrolyte and nanosilver.

[0010] Furthermore, the thickness of the halide layer is 1-10 μm.

[0011] Furthermore, the thickness of the sulfide layer is 2-30 μm.

[0012] Furthermore, the thickness of the polymer silver layer is 0.5-10 μm.

[0013] Furthermore, the chloride electrolyte includes at least one of Li3YCl6, Li2ZrCl6, Li3InCl6, Li2InCl5Br, Li3YBr3Cl3, Li3ScCl6 and Li3HoCl6.

[0014] Furthermore, the bromide electrolyte includes at least one of Li3PBr6, Li3SbBr6 and LiCrBr4.

[0015] Furthermore, the sulfide electrolyte includes Li2S-P2S5, Li7P3S 11 、Li6PS5Cl、Li 5.5 PS5Cl 1.5 、Li6PS5Br、Li6PS5I、Li 11 Si2PS 12 、Li 10 Sn2PS 12 He Li 10 Ge2P2S 12 At least one of .

[0016] Furthermore, the polymer electrolyte includes at least one of polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate and polyacrylonitrile.

[0017] Furthermore, in the polymer silver layer, the mass of the nanosilver accounts for 0.5% to 40% of the mass of the polymer silver layer.

[0018] Furthermore, the median particle size of the nanosilver is 1-100 nm.

[0019] Furthermore, the halide layer also includes a stabilizer.

[0020] Furthermore, the stabilizer includes at least one of aluminum oxide nanoparticles, magnesium oxide nanoparticles, zirconium oxide nanoparticles, silicon oxide nanoparticles, titanium oxide nanoparticles and zinc oxide nanoparticles.

[0021] Furthermore, the mass of the stabilizer accounts for 0.5% to 1% of the mass of the halide layer.

[0022] Furthermore, the sulfide layer also includes a lithium salt dopant.

[0023] Furthermore, the lithium salt dopant includes at least one of LiCl, LiBr, LiI and LiPF6.

[0024] Furthermore, the mass of the lithium salt dopant accounts for 1% to 2% of the mass of the sulfide layer.

[0025] Furthermore, the polymer silver layer further comprises additives, and the additives include plasticizers and / or surfactants.

[0026] Furthermore, the plasticizer includes at least one of ethylene carbonate, polyethylene glycol diacrylate, succinonitrile and glutaronitrile.

[0027] Furthermore, the mass of the plasticizer accounts for 0.5% to 1% of the mass of the polymer silver layer.

[0028] Furthermore, the surfactant includes at least one of sodium lauryl sulfate, sodium lauryl polyether sulfate, fatty alcohol polyoxyethylene ether phosphate, hexadecyltrimethylammonium bromide, fatty alcohol polyoxyethylene ether and polyethylene glycol-600 dioleate.

[0029] Furthermore, the mass of the surfactant accounts for 0.2% to 0.5% of the mass of the polymer silver layer.

[0030] The present invention further provides a method for preparing the above-mentioned composite electrolyte membrane, comprising the following steps: stacking a halide membrane, a sulfide membrane and a polymer silver membrane in sequence and laminating them to obtain a composite layer; alternatively, bonding the halide membrane, the sulfide membrane and the polymer silver membrane together using an adhesive to obtain a composite layer; and annealing the composite layer to obtain the composite electrolyte membrane.

[0031] Furthermore, the preparation method of the halide film includes: mixing a halide electrolyte with an organic solvent and pouring the mixture onto a substrate, followed by drying; or, mixing a halide electrolyte, a stabilizer and an organic solvent and pouring the mixture onto a substrate, followed by drying; or, hot pressing the halide electrolyte into shape; or, hot pressing the halide electrolyte into shape by mixing the halide electrolyte with a stabilizer; wherein the halide electrolyte includes a chloride electrolyte and / or a bromide electrolyte.

[0032] Furthermore, the preparation method of the sulfide film includes: ball milling the sulfide electrolyte and then hot pressing; or, mixing the sulfide electrolyte with a lithium salt dopant and then ball milling, and then hot pressing; or, mixing the sulfide electrolyte with a solvent and then casting it into a film, and then sintering; or, mixing the sulfide electrolyte, a lithium salt dopant and a solvent and then casting it into a film, and then sintering.

[0033] Furthermore, the preparation method of the polymer silver film includes: subjecting a mixed solution containing nanosilver, a monomer and an initiator to a polymerization reaction; or subjecting a mixed solution containing nanosilver, an additive, a monomer and an initiator to a polymerization reaction; or uniformly mixing a nanosilver dispersion with a polymer electrolyte solution, and then preparing the polymer silver film by solution casting or spin coating; or uniformly mixing a nanosilver dispersion, a polymer electrolyte solution and a solution of an additive, and then preparing the polymer silver film by solution casting or spin coating; wherein the additive includes a plasticizer and / or a surfactant.

[0034] The present invention also provides an all-solid-state battery comprising the above-mentioned composite electrolyte membrane.

[0035] Compared with the prior art, the present invention has the following beneficial effects: (1) The composite electrolyte membrane provided by the present invention has a halide layer that can contact the positive electrode to resist oxidation, thereby improving the antioxidant properties of the composite electrolyte membrane; the sulfide layer can improve ionic conductivity; and the nanosilver in the polymer silver layer can form a silver-lithium alloy, preventing the growth of lithium dendrites and improving the cycle performance of the composite electrolyte membrane and the battery made from it. This composite electrolyte membrane has excellent comprehensive performance and is suitable for large-scale application.

[0036] (2) The composite electrolyte membrane provided by the present invention can improve the structural stability of the halide layer by adding a stabilizer to the halide layer, thereby preventing problems such as grain boundary changes during the preparation and use process.

[0037] (3) The composite electrolyte membrane provided by the present invention can further improve the ionic conductivity of the composite electrolyte membrane by adding a lithium salt dopant to the sulfide layer, which helps to optimize the ion transmission channel of the sulfide layer and enhance the electrochemical performance of the composite electrolyte membrane and the battery prepared therefrom.

[0038] (4) The composite electrolyte membrane provided by the present invention introduces a plasticizer and / or a surfactant into the polymer silver layer. The plasticizer can improve the flexibility and ionic conductivity of the polymer, improve the interface compatibility between the polymer-based nanosilver electrolyte membrane and the other two layers, and the surfactant helps to uniformly disperse the nanosilver in the polymer matrix, thereby further optimizing the performance of the polymer-based nanosilver electrolyte membrane. DETAILED DESCRIPTION

[0039] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0040] Unless otherwise specified, in the present invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, terms such as "first," "second," "third," and "fourth" serve only as non-exhaustive enumeration and description, and should not constitute closed-ended limitations on quantity.

[0041] Unless otherwise specified, the terms "include" and "comprising" used in the present invention may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0042] Unless otherwise specified, in the present invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. Among them, "several" refers to any two or any two or more.

[0043] In a first aspect, the present invention provides a composite electrolyte membrane for an all-solid-state battery, comprising a halide layer, a sulfide layer, and a polymer silver layer stacked in sequence. Specifically, the sulfide layer serves as an intermediate layer and also as a transition layer.

[0044] Wherein, the halide layer is mainly composed of chloride electrolyte and / or bromide electrolyte.

[0045] The sulfide layer is mainly composed of a sulfide electrolyte.

[0046] The polymer silver layer mainly consists of polymer electrolyte and nano silver.

[0047] The halide layer, in contact with the positive electrode, resists oxidation, improving the composite electrolyte membrane's antioxidant properties. The sulfide layer enhances ionic conductivity. The nanosilver in the polymer silver layer forms a silver-lithium alloy, preventing lithium dendrite growth and improving the cycling performance of the composite electrolyte membrane and the resulting battery. This composite electrolyte membrane exhibits excellent overall performance and is suitable for large-scale applications.

[0048] Specifically, chloride electrolytes and / or bromide electrolytes have high ionic conductivity, good chemical stability, and good compatibility with electrode materials.

[0049] Sulfide electrolytes have high ionic conductivity and exhibit excellent ion transport properties, especially at room temperature.

[0050] Polymer electrolytes have good flexibility and processability; nanosilver, as a conductive enhancer, can significantly improve the ionic conductivity of polymer electrolytes. The polymer silver layer formed by polymer@silver can prevent the growth of lithium dendrites that can cause short circuits.

[0051] In some specific embodiments, nanosilver is uniformly dispersed in the polymer electrolyte to form a conductive path, which significantly improves the ionic conductivity of the polymer electrolyte.

[0052] In some specific embodiments, the thickness of the halide layer is 1 to 10 μm, including but not limited to any of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm, or any range therebetween. The halide layer faces the positive electrode, and adopting this thickness can improve the oxidation resistance of the electrolyte membrane.

[0053] In some specific embodiments, the thickness of the sulfide layer is 2 to 30 μm, including but not limited to any of 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, 28 μm, and 30 μm, or any range therebetween. The sulfide layer is positioned in the middle, and adopting this thickness can improve ionic conductivity.

[0054] In some specific embodiments, the polymer silver layer has a thickness of 0.5 to 10 μm, including but not limited to any one of 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm, or any range therebetween. The aforementioned thickness of the polymer silver layer can improve reduction resistance and prevent lithium dendrite penetration.

[0055] In some specific embodiments, the mass ratio of the halide layer, the sulfide layer, and the polymer silver layer is 3-4:3-4:2-4, for example, 3:3:4, 3:4:3, 4:3:3, or 4:4:2. The polymer silver layer primarily forms a dense layer to prevent soft penetration of lithium dendrites; the halide layer primarily separates the sulfide and the ternary cathode to prevent oxidation; and the intermediate sulfide layer primarily provides high ion conductivity. This helps improve the electrochemical performance of the composite electrolyte membrane.

[0056] In some specific embodiments, the chloride electrolyte includes at least one of Li3YCl6, Li2ZrCl6, Li3InCl6, Li2InCl5Br, Li3YBr3Cl3, Li3ScCl6 and Li3HoCl6.

[0057] In some specific embodiments, the bromide electrolyte includes at least one of Li3PBr6, Li3SbBr6 and LiCrBr4.

[0058] In some specific embodiments, the purity of the chloride electrolyte and / or the bromide electrolyte is ≥99.5%.

[0059] In some specific embodiments, the sulfide electrolyte includes Li2S-P2S5, Li7P3S 11 、Li6PS5Cl、Li 5.5 PS5Cl 1.5 、Li6PS5Br、Li6PS5I、Li 11 Si2PS 12 、Li 10 Sn2PS 12 He Li 10 Ge2P2S 12 At least one of .

[0060] In some specific embodiments, the purity of the sulfide electrolyte is ≥99%.

[0061] In some specific embodiments, the polymer electrolyte includes at least one of polyethylene oxide (PEO), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polymethyl methacrylate, and polyacrylonitrile.

[0062] In some specific embodiments, the molecular weight of polyethylene oxide is in the range of 10 5 ~10 6 Polyethylene oxide is a polymer with good flexibility and ion conductivity, which can provide a stable matrix structure for the electrolyte membrane.

[0063] In some specific embodiments, in the polymer silver layer, the mass of the nanosilver accounts for 0.5% to 40% of the mass of the polymer silver layer, including but not limited to any one of 0.5%, 1%, 3%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, and 40%, or any range therebetween, which is beneficial to improving the ionic conductivity of the composite electrolyte membrane. Preferably, the mass of the nanosilver accounts for 5% to 15% of the mass of the polymer silver layer, and more preferably 10%.

[0064] In some specific embodiments, the median particle size of the nanosilver is 1 to 100 nm, including but not limited to any one of 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, and 100 nm, or any range therebetween. Reducing the median particle size of the nanosilver can reduce the amount of silver used, thereby improving dispersibility while maintaining a constant amount of silver.

[0065] In some specific embodiments, the halide layer further includes a stabilizer, which is used to improve the structural stability of the halide layer and prevent problems such as grain boundary changes during preparation and use.

[0066] In some specific embodiments, the stabilizer includes at least one of aluminum oxide nanoparticles, magnesium oxide nanoparticles, zirconium oxide nanoparticles, silicon oxide nanoparticles, titanium oxide nanoparticles, and zinc oxide nanoparticles.

[0067] In some specific embodiments, the mass of the stabilizer accounts for 0.5% to 1% of the mass of the halide layer, including but not limited to any one of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1%, or a range between any two of them.

[0068] In some specific embodiments, the sulfide layer further includes a lithium salt dopant. The lithium salt dopant can further improve ionic conductivity. Such doping helps optimize the ion transport channels of the sulfide layer and enhance its electrochemical performance.

[0069] In some specific embodiments, the lithium salt dopant includes at least one of LiCl, LiBr, LiI and LiPF6.

[0070] In some specific embodiments, the mass of the lithium salt dopant accounts for 1% to 2% of the mass of the sulfide layer, including but not limited to any one of 1%, 1.2%, 1.3%, 1.5%, 1.6%, 1.8%, and 2%, or a range between any two of them.

[0071] In some specific embodiments, the polymer silver layer further includes additives, including plasticizers and / or surfactants. The plasticizer can increase the flexibility and ionic conductivity of the polymer, improving the interfacial compatibility between the polymer-based nanosilver electrolyte membrane and the other two layers. The surfactant facilitates uniform dispersion of the nanosilver in the polymer matrix, further optimizing the performance of the polymer-based nanosilver electrolyte membrane.

[0072] In some specific embodiments, the plasticizer includes at least one of ethylene carbonate (EC), polyethylene glycol diacrylate (PEGDA, MW≤1000), succinonitrile and glutaronitrile.

[0073] In some specific embodiments, the purity of ethylene carbonate is ≥99%.

[0074] In some specific embodiments, the mass of the plasticizer accounts for 0.5% to 1% of the mass of the polymer silver layer, including but not limited to any one of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1%, or a range between any two of them.

[0075] In some specific embodiments, the surfactant includes at least one of sodium dodecyl sulfate (SDS), sodium laureth sulfate, fatty alcohol polyoxyethylene ether phosphate, cetyltrimethylammonium bromide, fatty alcohol polyoxyethylene ether, and polyethylene glycol-600 dioleate.

[0076] In some specific embodiments, the purity of sodium lauryl sulfate is analytical grade.

[0077] In some specific embodiments, the mass of the surfactant accounts for 0.2% to 0.5% of the mass of the polymer silver layer, including but not limited to any one of 0.2%, 0.3%, 0.4%, and 0.5%, or a range between any two of them.

[0078] In a second aspect, the present invention provides a method for preparing the composite electrolyte membrane, comprising the following steps: A composite layer is formed by laminating a halide membrane, a sulfide membrane, and a polymer silver membrane in sequence and then laminating them under a certain temperature and pressure. Alternatively, a composite layer is formed by bonding a halide membrane, a sulfide membrane, and a polymer silver membrane together using an adhesive. The halide membrane, the sulfide membrane, and the polymer silver membrane, in sequence, form the halide layer, the sulfide layer, and the polymer silver layer of the composite electrolyte membrane.

[0079] During the lamination process, it is necessary to ensure that the layers are tightly fitted together without bubbles or gaps. The lamination temperature and pressure parameters can be optimized according to the properties of the three-layer materials to obtain good interface bonding and overall performance, which is not limited in the present invention.

[0080] The adhesive used in the bonding process must have good chemical stability and compatibility with the various layers of the electrolyte membrane. For example, a polymer adhesive can be used, but is not limited to such. The adhesive can be applied between the layers by solution coating or film bonding, and then cured under appropriate conditions to form a three-layer composite electrolyte membrane.

[0081] The composite layer is then subjected to an annealing treatment and cooled to obtain the composite electrolyte membrane. The annealing treatment can eliminate internal stress and improve the stability of the composite electrolyte membrane.

[0082] The preparation method is simple to operate, has a short process, and is suitable for batch production.

[0083] In some specific embodiments, the halide film preparation method includes: using a solution method, mixing a halide electrolyte with an organic solvent, pouring the mixture onto a substrate, and then drying; or, mixing a halide electrolyte, a stabilizer, and an organic solvent, pouring the mixture onto a substrate, and then drying. More specifically, the halide electrolyte or a mixture of a halide electrolyte and a stabilizer is dissolved in an organic solvent (such as acetonitrile, carbonates, etc.) to form a uniform solution; then, using a solution casting method, pouring the solution onto a flat substrate (such as a glass sheet, a polytetrafluoroethylene plate, etc.), controlling the film thickness with a scraper, and then drying at a certain temperature and vacuum conditions to evaporate the organic solvent, thereby obtaining the halide film.

[0084] Alternatively, a hot pressing method can be used to hot-press a halide electrolyte under a certain pressure and temperature, or to hot-press a halide electrolyte mixed with a stabilizer under a certain pressure and temperature. The hot pressing conditions can be optimized based on the properties of the halide to obtain a dense and uniform halide film, and the present invention does not limit the hot pressing conditions.

[0085] Wherein, the halide electrolyte includes a chloride electrolyte and / or a bromide electrolyte.

[0086] In some specific embodiments, the sulfide membrane preparation method includes: ball milling the sulfide electrolyte using a mechanical ball milling-hot pressing method, followed by hot pressing at high temperature and high pressure; or, mixing the sulfide electrolyte with a lithium salt dopant, ball milling the mixture, and then hot pressing at high temperature and high pressure. The ball milling is mechanical, which can refine particles and improve mixing uniformity. The hot pressing temperature and pressure are not limited in the present invention, but they should be selected to avoid decomposition and excessive sintering of the sulfide electrolyte to ensure the ionic conductivity and mechanical properties of the sulfide membrane.

[0087] Alternatively, a solution casting-sintering method is used, in which the sulfide electrolyte and the solvent (such as ionic liquid, etc.) are mixed evenly and then cast into a film, and then sintered to remove the solvent and improve the density of the film; or the sulfide electrolyte, lithium salt dopant and solvent (such as ionic liquid, etc.) are mixed evenly and then cast into a film, and then sintered to remove the solvent and improve the density of the film.

[0088] In some specific embodiments, the method for preparing the polymer silver film includes: using an in-situ polymerization method to subject a mixed solution containing nanosilver, a monomer (e.g., ethylene oxide monomer), and an initiator to a polymerization reaction, thereby generating a polymer electrolyte in situ around the nanosilver; or subjecting a mixed solution containing nanosilver, an additive, a monomer (e.g., ethylene oxide monomer), and an initiator to a polymerization reaction. The molecular weight of the polymer and the dispersion state of the nanosilver can be adjusted by controlling the polymerization reaction conditions (e.g., temperature, time, initiator concentration, etc.), and the present invention does not limit the polymerization reaction conditions.

[0089] Alternatively, a solution blending method is used to uniformly mix a nanosilver dispersion with a polymer electrolyte solution (such as an organic solution of PEO), and then the polymer silver film is prepared by solution casting or spin coating. Alternatively, a nanosilver dispersion, a polymer electrolyte solution and a solution of an additive are uniformly mixed, and then the polymer silver film is prepared by solution casting or spin coating. The additive includes a plasticizer and / or a surfactant.

[0090] In some specific embodiments, the annealing treatment further includes a cleaning step. Cleaning the surface of the composite electrolyte membrane can remove possible residual impurities and binders, thereby optimizing the interface performance between the composite electrolyte membrane and the electrode.

[0091] In a third aspect, the present invention provides an all-solid-state battery comprising the above-mentioned composite electrolyte membrane.

[0092] This all-solid-state battery not only has good safety performance, but also has high charge and discharge performance, high energy conversion efficiency, and excellent cycle performance.

[0093] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0094] Example 1 The method for preparing the composite electrolyte membrane provided in this embodiment includes the following steps: (1) Preparation of halide membrane: High-purity (99.8%) Li3YCl6 powder (chloride electrolyte) and Al2O3 nanoparticles with a median particle size of 30 nm (stabilizer) were mixed in a mass ratio of 99.5:0.5. The mixed materials were then hot-pressed at a pressure of 100 MPa and a temperature of 250°C for 30 min to obtain a halide electrolyte membrane with a thickness of 12 μm.

[0095] (2) Preparation of sulfide membrane: Li6PS5Cl powder (purity of 99.2%) and LiCl (median particle size of 3 μm, lithium salt dopant) were mixed in a mass ratio of 98:2.0 and ball-milled for 12 h to ensure that the components were fully mixed. The ball-milled mixed powder was then hot-pressed at a pressure of 100 MPa and 300 °C for 40 min to form a sulfide electrolyte membrane with a thickness of 35 μm.

[0096] (3) Preparation of polymer silver film: Nanosilver particles (median particle size of 50 nm) were dispersed in polyethylene oxide (PEO, molecular weight of 5×10 5 ) in N-methylpyrrolidone; then, ethylene carbonate (EC) and sodium dodecyl sulfate (SDS) were added and stirred to form a precursor solution. The mass ratio of polyethylene oxide, silver nanoparticles, ethylene carbonate, and sodium dodecyl sulfate in the precursor solution was 88.9:10:0.8:0.3. The precursor solution was solution-casted and dried at 60°C for 24 hours to obtain a polymer-based nanosilver electrolyte membrane with a thickness of 13 μm.

[0097] (4) Preparation of a composite electrolyte membrane: The prepared halide membrane, sulfide membrane, and polymer silver membrane were stacked in sequence and then laminated at 80°C and 400 MPa for 60 min (the thickness of each layer decreased after lamination, as shown in Table 1) to obtain a composite layer. Thereafter, the composite layer was annealed at 60°C for 2 h to eliminate internal stress, thereby obtaining a composite electrolyte membrane. The composite electrolyte membrane comprises a halide layer, a sulfide layer, and a polymer silver layer stacked in sequence.

[0098] Example 2 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that in step (1), the Li3YCl6 powder is replaced by an equal mass of bromide electrolyte Li3PBr6 (whose purity is 99.87%).

[0099] Example 3 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in embodiment 1, except that in step (2), the Li6PS5Cl powder is replaced by an equal mass of Li 10 GeP2S 12 Powder (99.9% purity).

[0100] Example 4 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that in step (3), polyethylene oxide is replaced by polyvinylidene fluoride-hexafluoropropylene of equal mass.

[0101] Example 5 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that in step (3), the median particle size of the nanosilver particles is replaced with 100 nm.

[0102] Example 6 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that in step (3), the mass ratio of polyethylene oxide, nanosilver particles, ethylene carbonate and sodium lauryl sulfate in the precursor solution is replaced with 78.9:20:0.8:0.3.

[0103] Example 7 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that in step (1), the mass ratio of Li3YCl6 powder to Al2O3 nanoparticles is replaced with 99:1.

[0104] Example 8 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that in step (2), the mass ratio of Li6PS5Cl powder to LiCl is replaced with 97.5:2.5.

[0105] Example 9 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that in step (3), the mass ratio of polyethylene oxide, nanosilver particles, ethylene carbonate and sodium lauryl sulfate in the precursor solution is replaced with 88.7:10:1:0.3.

[0106] Example 10 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that: step (1) controls the thickness of the halide film to be 10 μm, step (2) controls the thickness of the sulfide film to be 30 μm, step (3) controls the thickness of the polymer silver film to be 10 μm, and step (4) is: using a polymer binder to bond the halide film, the sulfide film and the polymer silver film together to obtain a composite electrolyte membrane in which the halide layer, the sulfide layer and the polymer silver layer are stacked in sequence.

[0107] Example 11 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that: Al2O3 nanoparticles are not added in step (1), that is, there is no stabilizer in the halide membrane.

[0108] Example 12 The preparation method of the composite electrolyte membrane provided in this embodiment is basically the same as that in Example 1, except that LiCl is not added in step (2).

[0109] Comparative Example 1 The preparation method of the composite electrolyte membrane provided in this comparative example is basically the same as that of Example 1, except that no nanosilver particles are added in step (3).

[0110] Comparative Example 2 The preparation method of the composite electrolyte membrane provided in this comparative example is basically the same as that of Example 1, except that ethylene carbonate is not added in step (3).

[0111] Comparative Example 3 The preparation method of the composite electrolyte membrane provided in this comparative example is basically the same as that of Example 1, except that sodium lauryl sulfate is not added in step (3).

[0112] Comparative Example 4 The preparation method of the composite electrolyte membrane provided in this comparative example is basically the same as that in Example 1, except that: in step (4), no halide membrane is stacked, but the prepared sulfide membrane and polymer silver membrane are stacked in sequence, that is, the composite electrolyte membrane prepared in this comparative example does not contain a halide layer.

[0113] Comparative Example 5 The preparation method of the composite electrolyte membrane provided in this comparative example is basically the same as that in Example 1, except that: in step (4), the sulfide membrane is not stacked, but the prepared halide membrane and polymer silver membrane are stacked in sequence, that is, the composite electrolyte membrane prepared in this comparative example does not contain a sulfide layer.

[0114] Comparative Example 6 The preparation method of the composite electrolyte membrane provided in this comparative example is basically the same as that in Example 1, except that: in step (4), the polymer silver film is not stacked, but the prepared halide film and sulfide film are stacked in sequence, that is, the composite electrolyte membrane prepared in this comparative example does not contain a polymer silver layer.

[0115] The thickness of the halide layer, the thickness of the sulfide layer, and the thickness of the polymer silver layer of the composite electrolyte membranes prepared in each embodiment and each comparative example are shown in Table 1.

[0116] Table 1 Parameters of various composite electrolyte membranes

[0117] Experimental example The following performance tests were performed on the composite electrolyte membranes prepared in each embodiment and each comparative example: Ionic conductivity test: The ionic conductivity of each composite electrolyte membrane was tested at 25°C and 60°C using the AC impedance spectroscopy method.

[0118] Mechanical property test: The elongation at break of each composite electrolyte membrane was tested by a tensile test.

[0119] Electrochemical stability test: Linear sweep voltammetry (LSV) was used to test the electrochemical stability window of each composite electrolyte membrane at a scan rate of 1 mV / s.

[0120] Table 2 Performance test results of various composite electrolyte membranes

[0121] Table 2 shows that the composite electrolyte membranes produced in Examples 1-10 exhibit high ionic conductivities at both 25°C and 60°C, demonstrating that the composite electrolyte membranes produced in each example exhibit excellent ionic conductivity over a wide temperature range. Furthermore, the composite electrolyte membranes produced in Examples 1-10 exhibit high elongation at break, demonstrating excellent mechanical properties and the ability to withstand the stresses experienced during battery assembly and use. Furthermore, the composite electrolyte membranes produced in Examples 1-10 exhibit a high electrochemical stability window, meeting the requirements of most battery systems.

[0122] The ionic conductivity at 25° C. and 60° C. of Example 11 is lower than that of Example 1, and the elongation at break is also lower than that of Example 1. This indicates that the aluminum oxide nanoparticle stabilizer has a significant effect on improving the performance of the halide electrolyte membrane.

[0123] The ionic conductivity of Example 12 at 25° C. and 60° C. is significantly lower than that of Example 1, and the electrochemical stability window is also significantly reduced, which indicates that the LiCl dopant has a significant effect on improving the performance of the sulfide electrolyte membrane.

[0124] The battery cycle performance of Comparative Example 1 is significantly lower than that of Example 1, which indicates that nanosilver plays a key role in improving the cycle performance of the composite electrolyte membrane.

[0125] The ionic conductivity of Comparative Example 2 at 25° C. and 60° C. is lower than that of Example 1, which indicates that the plasticizer has a certain effect on improving the ionic conductivity of the polymer-based electrolyte membrane.

[0126] The battery cycle performance of Comparative Example 3 is significantly lower than that of Example 1, which indicates that the dispersant is crucial for improving the dispersion uniformity of nanosilver, thereby affecting the cycle performance of the composite electrolyte membrane.

[0127] The electrochemical window of Comparative Example 4 is significantly lower than that of Example 1, which indicates that the halide electrolyte layer has a positive effect on improving the electrochemical window of the composite membrane.

[0128] The ion conductivity of Comparative Example 5 is lower than that of Example 1, which shows that the sulfide electrolyte layer is of great significance for improving the ion conductivity of the composite electrolyte membrane.

[0129] The battery cycle performance of Comparative Example 6 is lower than that of Example 1, which shows that the polymer electrolyte layer is important for inhibiting lithium dendrites and thus improving the cycle.

[0130] It can be seen that the composite electrolyte membrane with a specific composite structure provided by the present invention has excellent comprehensive performance and is suitable for large-scale application.

[0131] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are merely intended to illustrate the technical solutions of the present invention rather than to limit them. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and scope of the present invention. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A composite electrolyte membrane, characterized in that It comprises a halide layer, a sulfide layer and a polymer silver layer stacked in sequence; The material of the halide layer includes a chloride electrolyte and / or a bromide electrolyte; The material of the sulfide layer includes a sulfide electrolyte; The materials of the polymer silver layer include polymer electrolyte and nano silver.

2. The composite electrolyte membrane according to claim 1, characterized in that At least one of the following conditions is met: (1) The thickness of the halide layer is 1 to 10 μm; (2) The thickness of the sulfide layer is 2 to 30 μm; (3) The thickness of the polymer silver layer is 0.5-10 μm.

3. The composite electrolyte membrane according to claim 1, characterized in that At least one of the following conditions is met: (1) The chloride electrolyte includes at least one of Li3YCl6, Li2ZrCl6, Li3InCl6, Li2InCl5Br, Li3YBr3Cl3, Li3ScCl6 and Li3HoCl6; (2) The bromide electrolyte includes at least one of Li3PBr6, Li3SbBr6 and LiCrBr4; (3) The sulfide electrolyte includes Li2S-P2S5, Li7P3S 11 、Li6PS5Cl、Li 5.5 PS5Cl 1.5 、Li6PS5Br、Li6PS5I、Li 11 Si2PS 12 、Li 10 Sn2PS 12 He Li 10 Ge2P2S 12 At least one of; (4) The polymer electrolyte includes at least one of polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate and polyacrylonitrile.

4. The composite electrolyte membrane according to claim 1, characterized in that In the polymer silver layer, the mass of the nanosilver accounts for 0.5% to 40% of the mass of the polymer silver layer; And / or, the median particle size of the nanosilver is 1-100 nm.

5. The composite electrolyte membrane according to any one of claims 1 to 4, characterized in that The halide layer also includes a stabilizer; The stabilizer comprises at least one of aluminum oxide nanoparticles, magnesium oxide nanoparticles, zirconium oxide nanoparticles, silicon oxide nanoparticles, titanium oxide nanoparticles and zinc oxide nanoparticles; The mass of the stabilizer accounts for 0.5% to 1% of the mass of the halide layer.

6. The composite electrolyte membrane according to any one of claims 1 to 4, characterized in that The sulfide layer also includes a lithium salt dopant; The lithium salt dopant includes at least one of LiCl, LiBr, LiI and LiPF6; The mass of the lithium salt dopant accounts for 1% to 2% of the mass of the sulfide layer.

7. The composite electrolyte membrane according to any one of claims 1 to 4, characterized in that The polymer silver layer further includes additives, wherein the additives include plasticizers and / or surfactants; The plasticizer includes at least one of ethylene carbonate, polyethylene glycol diacrylate, succinonitrile and glutaronitrile; The mass of the plasticizer accounts for 0.5% to 1% of the mass of the polymer silver layer; The surfactant includes at least one of sodium lauryl sulfate, sodium laureth sulfate, fatty alcohol polyoxyethylene ether phosphate, cetyltrimethylammonium bromide, fatty alcohol polyoxyethylene ether and polyethylene glycol-600 dioleate; The mass of the surfactant accounts for 0.2% to 0.5% of the mass of the polymer silver layer.

8. The method for preparing a composite electrolyte membrane according to any one of claims 1 to 7, wherein: The steps include: The halide film, the sulfide film and the polymer silver film are stacked in sequence and laminated to obtain a composite layer; or the halide film, the sulfide film and the polymer silver film are bonded together using an adhesive to obtain a composite layer; The composite layer is subjected to annealing treatment to obtain the composite electrolyte membrane.

9. The method for preparing a composite electrolyte membrane according to claim 8, wherein: At least one of the following conditions is met: (1) The method for preparing the halide film comprises: mixing a halide electrolyte with an organic solvent and pouring the mixture onto a substrate, followed by drying; or mixing a halide electrolyte, a stabilizer, and an organic solvent and pouring the mixture onto a substrate, followed by drying; or hot pressing the halide electrolyte; or hot pressing the halide electrolyte with a stabilizer; wherein the halide electrolyte comprises a chloride electrolyte and / or a bromide electrolyte; (2) The method for preparing the sulfide film comprises: ball milling the sulfide electrolyte and then hot pressing; or, mixing the sulfide electrolyte with a lithium salt dopant and then ball milling and then hot pressing; or, mixing the sulfide electrolyte with a solvent and then casting it into a film and then sintering; or, mixing the sulfide electrolyte, a lithium salt dopant and a solvent and then casting it into a film and then sintering; (3) The method for preparing the polymer silver film comprises: subjecting a mixed solution containing nanosilver, a monomer and an initiator to a polymerization reaction; or subjecting a mixed solution containing nanosilver, an additive, a monomer and an initiator to a polymerization reaction; or uniformly mixing a nanosilver dispersion with a polymer electrolyte solution, and then preparing the polymer silver film by solution casting or spin coating; or uniformly mixing a nanosilver dispersion, a polymer electrolyte solution and a solution of an additive, and then preparing the polymer silver film by solution casting or spin coating; wherein the additive comprises a plasticizer and / or a surfactant.

10. An all-solid-state battery, characterized in that: Comprising the composite electrolyte membrane according to any one of claims 1 to 7.

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