A composite solid electrolyte membrane having lewis acid and lewis base sites and a solid-state battery

Abstract

The present application relates to a kind of composite solid electrolyte membrane with Lewis acid and Lewis base site and solid-state battery, belong to solid electrolyte technical field.The composite solid electrolyte membrane of the present application includes nanofiber support film, polymer electrolyte and lithium salt, the nanofiber support film includes first oxide and second oxide different from the first oxide, the first oxide has Lewis acid site, the second oxide has Lewis base site, the Lewis acid site is at least partially provided by TiO2 with defect, the Lewis base site is at least partially provided by LLZO series oxide.The composite solid electrolyte membrane of the present application has continuous conductive network, while in situ creates Lewis acidic site and Lewis basic site, significantly improves lithium ion conductivity.

Description

Technical Field

[0001] This invention belongs to the field of new energy, particularly the field of solid electrolyte technology, and specifically relates to a composite solid electrolyte membrane and solid battery having Lewis acid and Lewis base sites. Background Technology

[0002] Traditional solid electrolyte membranes typically consist of polymers, lithium salts, and inorganic particles. The inorganic particles provide Lewis acidic or basic sites for the lithium salts to facilitate the adsorption, transfer, or dissociation of lithium ions.

[0003] Some literature describes solid electrolyte membranes containing Lewis acid lithium salts, lithium-philic perchlorates, and polyoxyethylene polymers. The Lewis acid lithium salts serve as catalysts and ion conductors, avoiding the need for additional polymer initiators. However, these solid electrolyte membranes exhibit low conductivity.

[0004] Some literature describes solid electrolyte membranes that use a coating layer containing aprotic Lewis acids to coat sulfide solid electrolytes, thereby targeting and stabilizing the Lewis basic reaction sites of the sulfide solid electrolytes and significantly reducing their probability of reaction with moisture in the air. The conductivity of such solid electrolyte membranes is within a suitable range.

[0005] Traditional electrolyte membranes using inorganic particulate fillers lack a continuous conductive network, affecting lithium-ion transfer and limiting lithium-ion conductivity. In recent years, some studies have used long-chain fibers to replace inorganic fillers to provide a continuous conductive network. For example, some literature uses nanofiber membranes containing Lewis basic sites as solid electrolyte membranes, while others use nanofiber membranes containing Lewis acidic sites. However, these single-fiber networks can only provide a single Lewis acid or Lewis basic site. Summary of the Invention

[0006] The problem the invention aims to solve

[0007] As mentioned earlier, while traditional blending (extrusion) film-forming methods can accommodate both acidic and basic sites, they often fail to create a continuous and highly efficient conductive network. Furthermore, a single fiber network provides only a single Lewis acid or Lewis base site. For example, solid electrolyte fibers provide continuous Lewis basic sites, which only enhances lithium-ion transfer, while fibers providing Lewis acid sites only promote lithium salt dissociation.

[0008] In view of this, the present invention proposes a composite solid electrolyte membrane that simultaneously possesses Lewis acid and Lewis base sites. The Lewis acid sites promote lithium salt dissociation, while the Lewis base sites promote lithium ion transport, thereby improving the overall ionic conductivity.

[0009] In addition, the present invention also provides a solid-state battery comprising the composite solid-state electrolyte membrane of the present invention.

[0010] Solution for solving the problem

[0011] This invention first provides a composite solid electrolyte membrane having Lewis acid and Lewis base sites. The composite solid electrolyte membrane includes a nanofiber support membrane, a polymer electrolyte, and a lithium salt. The nanofiber support membrane includes a first oxide and a second oxide different from the first oxide. The first oxide has Lewis acid sites, and the second oxide has Lewis base sites. The Lewis acid sites are at least partially provided by defective TiO2, and the Lewis base sites are at least partially provided by LLZO-based oxides. The LLZO-based oxides include one or more of undoped LLZO and LLZO doped with other metals. Furthermore, the content of the first oxide and the second oxide is 30%-60% by mass based on the total mass of the composite solid electrolyte membrane.

[0012] According to the composite solid electrolyte membrane of the present invention, the nanofiber support membrane comprises a matrix fiber formed of the first oxide and second oxide particles formed on at least a portion of the surface of the matrix fiber; or, the nanofiber support membrane comprises a matrix fiber formed of the second oxide and first oxide particles formed on at least a portion of the surface of the matrix fiber.

[0013] According to the composite solid electrolyte membrane of the present invention, the first oxide is substantially formed of the defective TiO2, and the second oxide is substantially formed of LLZO-based oxide.

[0014] According to the composite solid electrolyte membrane of the present invention, the LLZO-based oxide is further doped with one or more elements selected from aluminum (Al), niobium (Nb), tantalum (Ta), zirconium (Zr) and gallium (Ga).

[0015] According to the composite solid electrolyte membrane of the present invention, the composite solid electrolyte membrane has one or more of the following characteristics:

[0016] The composite solid electrolyte membrane exhibits an ionic conductivity of over 0.7 mS / cm under conditions of room temperature (25°C) and humidity (50%).

[0017] The thickness of the composite solid electrolyte membrane is 20-50 μm.

[0018] Furthermore, the present invention also provides a method for preparing the composite solid electrolyte membrane described herein, the method comprising:

[0019] S1:

[0020] S1a) Prepare a first oxide matrix fiber by electrospinning, and then immerse the first oxide matrix fiber in a second oxide precursor solution; or...

[0021] S1b) The second oxide matrix fiber is prepared by electrospinning, and then the second oxide matrix fiber is immersed in the first oxide precursor solution;

[0022] S2: Drying and calcining to obtain the nanofiber supported membrane;

[0023] S3: Immerse the polymer electrolyte and lithium salt in the nanofiber support membrane obtained in step S2, and dry to obtain the composite solid electrolyte membrane.

[0024] According to the preparation method of the present invention, the first oxide is defective TiO2, and the precursor of the defective TiO2 includes at least one of tetrabutyl titanate, titanium isopropoxide and nano TiO2; the second oxide is an LLZO-based oxide, and the precursor of the LLZO-based oxide includes a soluble lithium source, lanthanum source, aluminum source and zirconium source.

[0025] According to the preparation method of the present invention, the lithium source is at least one of lithium nitrate, lithium hydroxide and lithium acetate, the lanthanum source is at least one of lanthanum nitrate and lanthanum acetate, the aluminum source is at least one of aluminum nitrate and aluminum acetate, and the zirconium source is at least one of zirconium oxynitrate and zirconium acetate.

[0026] According to the preparation method of the present invention, in step S2, the calcination temperature is 500-1000℃.

[0027] Furthermore, the present invention also provides a solid-state battery, which includes a composite solid-state electrolyte membrane according to the present invention or a composite solid-state electrolyte membrane obtained by the preparation method according to the present invention.

[0028] The solid-state battery according to the present invention is a power battery for transportation vehicles, a battery for personal consumer electronics, or an energy storage battery for energy storage systems.

[0029] The effects of the invention

[0030] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0031] The composite solid electrolyte membrane of the present invention uses a composite fiber membrane to replace the traditional inorganic particulate filler, and has a continuous conductive network, thereby improving the lithium ion transfer efficiency and the ionic conductivity of the solid electrolyte membrane.

[0032] Meanwhile, this invention simultaneously creates Lewis acidic sites and Lewis basic sites in situ on the composite fiber membrane. The acidic sites promote lithium ion dissociation, and the basic sites enhance lithium ion movement. By combining the Lewis acidic and Lewis basic sites, the energy barrier for lithium ion transfer is reduced, further improving the lithium ion conductivity of the solid electrolyte membrane of this invention. Detailed Implementation

[0033] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0034] In this specification, the range of values ​​referred to as “value A - value B” is the range that includes the endpoint values ​​A and B.

[0035] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0036] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0037] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0038] In this instruction manual, "normal temperature" or "room temperature" refers to an indoor ambient temperature of "23±2℃".

[0039] All unit names used in this manual are international standard unit names, and unless otherwise stated, the "%" indicates weight or mass percentage.

[0040] In this specification, the terms "substantially" and "essentially" are used to indicate that the standard deviation from the theoretical model, theoretical data, or target data is within a range of 2%, preferably 1%, and more preferably 0.8%.

[0041] In this specification, the terms “comprising” and / or “including” are used to indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0043] This invention primarily provides a composite solid electrolyte membrane, comprising a nanofiber support membrane, a polymer electrolyte, and a lithium salt. The nanofiber support membrane has a continuous conductive network, thereby improving the lithium-ion transfer efficiency. Simultaneously, this invention creates Lewis acid sites and Lewis base sites in situ within the nanofiber support membrane. The acidic sites promote lithium-ion dissociation, while the base sites enhance lithium-ion mobility. The Lewis acid and Lewis base sites complement each other, and their combination further improves the lithium-ion conductivity of the solid electrolyte membrane of this invention.

[0044] First aspect

[0045] The present invention provides a composite solid electrolyte membrane having Lewis acid and Lewis base sites, wherein the composite solid electrolyte membrane comprises a nanofiber support membrane, a polymer solid electrolyte, and a lithium salt.

[0046] The nanofiber support membrane includes a first oxide and a second oxide that is different from the first oxide.

[0047] The first oxide provides Lewis acidic sites. Commonly used oxides include one or more of the following: defective TiO2, ZrO2, Cr2O3, SnO2, V2O5, Al2O3, CeO2, etc. Furthermore, considering conductivity, processability, and economy, the first oxide contains at least defective TiO2. More preferably, the first oxide contains 50% by mass or more, 70% by mass or more, or 90% by mass or more of defective TiO2. In a more preferred embodiment, the first oxide is substantially formed of defective TiO2.

[0048] The term "defective" refers to the presence of non-ideal atomic arrangements or stoichiometric deviations in the crystal structure of the aforementioned oxides (e.g., TiO2), typically manifested as oxygen vacancies, titanium interstitials, or surface hydroxyl groups. These defects significantly alter the electronic structure, band structure, and surface reactivity of the material, thereby affecting its photoelectrocatalytic performance. In some specific embodiments, the defective element is an oxide with oxygen vacancies.

[0049] The second oxide provides Lewis basic sites, and such oxides can be doped or undoped LLZO-based oxides.

[0050] LLZO (Li7La3Zr2O) 12 It is a garnet-type solid electrolyte oxide with high ionic conductivity (0.1-1 mS / cm @ 25℃) and good chemical stability.

[0051] For the metal elements that can be further doped into LLZO, in some specific implementations, one or more of aluminum (Al), niobium (Nb), tantalum (Ta), zirconium (Zr) and gallium (Ga) may be included. Preferably, the metal elements that can be doped include at least aluminum (Al).

[0052] In some specific implementations, the LLZO is Li 6.4 Al 0.2 La3Zr2O 12 .

[0053] Furthermore, in some other specific embodiments, in addition to the first and second oxides described above, other oxides different from the oxides described above can be used in the nanofiber support membrane of the present invention. Preferably, the content of these additional oxides accounts for less than 10% by mass, less than 8% by mass, or even less than 5% by mass, less than 2% by mass, less than 1% by mass, etc. of the total mass of the nanofiber support membrane.

[0054] Furthermore, in some preferred embodiments, in the nanofiber support membrane of the present invention, the Lewis acid sites are substantially entirely provided by defective TiO2, and the Lewis base sites are provided by LLZO-based oxides.

[0055] Furthermore, regarding the specific structure of the aforementioned nanofiber support membrane, in some specific embodiments of the present invention, the structure can be formed by matrix fibers and particles formed on at least part (but not all) of the surface of the matrix fibers.

[0056] In some specific embodiments, the matrix fibers may be formed primarily of the first oxide, and the particles may be formed primarily of the second oxide. Alternatively, in other specific embodiments, the matrix fibers may be formed primarily of the second oxide, and the particles may be formed primarily of the first oxide. The particles may exist only on the surface of a single matrix fiber, or they may be connected to multiple fiber surfaces.

[0057] Furthermore, in some preferred embodiments, the nanofiber support membrane comprises matrix fibers formed from defective TiO2 and particles formed from LLZO-based oxides.

[0058] In some other preferred embodiments, the nanofiber support membrane comprises LLZO-based oxide matrix fibers and defective TiO2 particles.

[0059] The matrix fibers described above typically have a diameter of 100-300 nm, preferably 150-250 nm or 180-220 nm.

[0060] For the above-mentioned particles, the average particle size is less than 1 micrometer, for example, it can be 100 nm, 300 nm, 500 nm, 800 nm, etc., preferably 100-900 nm.

[0061] Furthermore, based on the total mass of the composite solid electrolyte membrane, the total content of the first oxide and the second oxide is 30%-60% by mass, for example, 35%, 40%, 45%, 50%, 55%, etc., preferably 40%-50% by mass.

[0062] In some specific embodiments, the matrix fibers may be formed from the first oxide, and the particles may be formed from the second oxide. Based on the total mass of the composite solid electrolyte membrane, the content of the first oxide is 28%-59.5% by mass, for example, 30%, 40%, 45%, 50%, 55%, etc., preferably 40%-50% by mass. The content of the second oxide is 0.5%-2% by mass, for example, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.5% by mass, etc., preferably 0.6%-1.2% by mass. Alternatively, in some other specific embodiments, the matrix fibers may be formed from the second oxide, and the particles may be formed from the first oxide. The content of the second oxide, based on the total mass of the composite solid electrolyte membrane, is 28%-59.5% by mass, for example, 30%, 40%, 45%, 50%, 55%, etc., preferably 40%-50% by mass. The content of the first oxide is 0.5%-2% by mass, for example, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.5% by mass, etc., preferably 0.6%-1.2% by mass.

[0063] There are no particular restrictions in principle on the polymer solid electrolytes that can be used in the composite solid electrolyte membrane of the present invention. In some specific embodiments, the polymer solid electrolytes can be selected from one or more of the following: polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polysiloxane (PS), polycarbonate, etc.

[0064] Furthermore, there are no particular restrictions in principle on the lithium salts that can be used in the composite solid electrolyte membrane of the present invention. Preferably, fluorine-containing lithium salts can be used, such as one or more selected from lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium dioxolaneborate (LiBOB), etc.

[0065] The structure of the composite solid electrolyte membrane of the present invention can typically be that the polymer electrolyte encapsulates / or fills the nanofiber support membrane, while lithium salt is dispersed in the composite structure.

[0066] In addition, the composite solid electrolyte membrane of the present invention may optionally contain one or more other types of solid electrolytes, additives (e.g., conductive agents), etc., besides the components mentioned above.

[0067] Furthermore, the composite solid electrolyte membrane of the present invention has a high ionic conductivity. In some embodiments, the ionic conductivity of the composite solid electrolyte membrane of the present invention under room temperature (25°C) and humidity (50%) is 0.7 mS / cm or higher, for example, 0.75 mS / cm, 0.9 mS / cm, 1 mS / cm, 1.2 mS / cm, 1.3 mS / cm, 1.5 mS / cm, 2 mS / cm, 5 mS / cm, etc., preferably 1.2 mS / cm or higher.

[0068] Furthermore, there is no particular limitation on the thickness of the composite solid electrolyte membrane of the present invention, but it is preferably 20-50 μm, such as 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, etc.

[0069] Second aspect

[0070] The present invention also provides a method for preparing the composite solid electrolyte membrane described in the present invention, especially the method for preparing the composite solid electrolyte membrane of the first aspect above.

[0071] The preparation method includes the following steps:

[0072] S1:

[0073] S1a) Prepare a first oxide matrix fiber by electrospinning, and then immerse the first oxide matrix fiber in a second oxide precursor solution; or...

[0074] S1b) The second oxide matrix fiber is prepared by electrospinning, and then the second oxide matrix fiber is immersed in the first oxide precursor solution;

[0075] S2: Drying and calcining to obtain a nanofiber supported membrane;

[0076] S3: Immerse the polymer electrolyte and lithium salt in the nanofiber support membrane obtained in step S2, and dry to obtain the composite solid electrolyte membrane.

[0077] For step S1:

[0078] For the preparation of matrix fibers of the first or second oxide by electrospinning, the first or second oxide spinning raw material can be added to the electrospinning equipment, and the precursor of the corresponding matrix fiber can be obtained by extrusion through the nozzle of the equipment, and then further calcined to obtain the first or second oxide matrix fiber.

[0079] The first or second oxide spinning raw materials mentioned above may include: precursor compounds containing various metal elements, solvents, binders, and other available processing aids.

[0080] For the spinning raw material of the first oxide, it preferably includes a TiO2 precursor compound, a binder and a solvent. In some specific embodiments, the TiO2 precursor compound includes at least one of tetrabutyl titanate, titanium isopropoxide and nano-TiO2.

[0081] For the spinning raw material of the second oxide, it preferably includes a soluble lithium source, lanthanum source, aluminum source, zirconium source, binder, and solvent. In some specific embodiments, the lithium source is at least one selected from lithium nitrate, lithium hydroxide, and lithium acetate; the lanthanum source is at least one selected from lanthanum nitrate and lanthanum acetate; the aluminum source is at least one selected from aluminum nitrate and aluminum acetate; and the zirconium source is at least one selected from zirconium oxynitrate and zirconium acetate. The term "soluble" means that the lithium source, lanthanum source, aluminum source, and zirconium source are soluble in the solvent of the spinning raw material of the second oxide.

[0082] In the case where the second oxide contains additional doped metal elements, the spinning raw material of the second oxide may also include at least one of the nitrates and acetates of these doped metal elements.

[0083] Furthermore, in the impregnation stage after fiber formation, the first oxide precursor solution preferably uses a solution comprising at least one of tetrabutyl titanate, titanium isopropoxide, and nano-TiO2. The second oxide precursor solution is preferably a solution comprising a lithium source, a lanthanum source, an aluminum source, and a zirconium source. In some specific embodiments, the lithium source is at least one of lithium nitrate, lithium hydroxide, and lithium acetate; the lanthanum source is at least one of lanthanum nitrate and lanthanum acetate; the aluminum source is at least one of aluminum nitrate and aluminum acetate; and the zirconium source is at least one of zirconium oxynitrate and zirconium acetate. If the second oxide contains additional doped metal elements, the second oxide precursor solution may also use at least one of the nitrates and acetates of these doped metal elements.

[0084] There are no particular restrictions on the solvents applicable to the above situations. They can be selected based on the actual instrument used or the solubility of the solvent. For example, they can include organic acids, polar organic solvents, water, etc.

[0085] In some embodiments, the method for preparing the TiO2 matrix fiber includes the following steps:

[0086] A spinning solution containing a TiO2 precursor compound, a binder, and a solvent was prepared, and electrospinning was performed to obtain nanofibers; the nanofibers were then calcined to obtain TiO2 matrix fibers.

[0087] In some specific implementations, the adhesive may be selected from: polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyurethane (PU), etc.

[0088] In some specific implementations, the solvent may be selected from N,N-dimethylformamide, chloroform, etc.

[0089] In some specific embodiments, the calcination temperature is 500-1000℃, such as 550℃, 600℃, 650℃, 700℃, 800℃, 900℃, etc., preferably 600-800℃. In some specific embodiments, the calcination time is 1-5 h, such as 2 h, 3 h, 4 h, etc.

[0090] In some embodiments, the method for preparing the LLZO-based oxide matrix fiber includes the following steps:

[0091] A spinning solution containing LLZO-based oxide precursor compounds, binders, and solvents was prepared, and electrospinning was performed to obtain nanofibers; the nanofibers were then calcined to obtain LLZO-based oxide matrix fibers.

[0092] In some specific implementations, the adhesive may be selected from: polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyurethane (PU), etc.

[0093] In some specific implementations, the solvent may be selected from N,N-dimethylformamide, chloroform, etc.

[0094] In some specific embodiments, the calcination temperature is 500-1000℃, such as 600℃, 700℃, 750℃, 800℃, 850℃, 900℃, etc., preferably 800-1000℃. In some specific embodiments, the calcination time is 1-5 h, such as 2 h, 3 h, 4 h, etc.

[0095] Furthermore, the matrix fibers obtained above can be immersed in the corresponding precursor solution, so that the corresponding precursor is adsorbed on the surface of the matrix fibers.

[0096] For step S2:

[0097] In step S2, the matrix fibers that have adsorbed the precursor solution are dried and calcined so that particles precipitate on the surface of the matrix fibers.

[0098] In some implementations, in step S2, drying refers to evaporating the solvent in the precursor solution; in some specific implementations, the drying temperature is 80-120℃, such as 90℃, 100℃, 110℃, etc.; in some specific implementations, the drying time is 6-12 h, such as 7 h, 8 h, 9 h, 10 h, etc.

[0099] In some implementations, the calcination temperature in step S2 is 500-1000℃, such as 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, etc.

[0100] In some preferred embodiments, when TiO2 matrix fibers are prepared in step S1, the calcination temperature in step S2 is 800-1000℃, such as 800℃, 850℃, 900℃, 950℃, etc.

[0101] In some other preferred embodiments, when the LLZO-based oxide fiber is prepared in step S1, the calcination temperature in step S2 is 500-800℃, for example, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, etc.

[0102] In some implementations, the calcination time in step S2 can be 1-5 hours, such as 2 hours, 3 hours, 4 hours, etc.

[0103] In some embodiments, the calcination in step S2 is carried out in an inert gas atmosphere. Specifically, the inert gas can be selected from nitrogen, argon, helium, etc.

[0104] For step S3:

[0105] In some implementations, in step S3, the polymer electrolyte may be selected from: polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polysiloxane (PS), polycarbonate, etc.

[0106] In some specific embodiments, in step S3, the polymer electrolyte is immersed in the nanofiber support membrane in the form of a solution. Further, the concentration of the polymer electrolyte solution can be 5-30 wt%, for example, 8 wt%, 10 wt%, 15 wt%, 20 wt%, etc. Further, the solvent of the polymer electrolyte solution can be water, N,N-dimethylformamide, etc.

[0107] In some specific implementations, in step S3, the lithium salt can be a fluorinated lithium salt, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium dioxolaneborate (LiBOB), etc.

[0108] In some specific embodiments, in step S3, the lithium salt is immersed in the nanofiber support membrane in the form of a solution. Further, the concentration of the lithium salt solution is 0.05-0.5 mol / L, for example, 0.08 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, etc. Further, the solvent of the lithium salt solution is N,N-dimethylformamide, water, etc.

[0109] In addition, in step S3, the drying refers to evaporating the solvent in the polymer electrolyte and the lithium salt solution; in some specific embodiments, the drying temperature is 100-150℃, such as 110℃, 120℃, 130℃, 140℃, etc.; in some specific embodiments, the drying time is 6-12 h, such as 7 h, 8 h, 9 h, 10 h, etc.

[0110] Third aspect

[0111] The present invention also provides a solid-state battery, wherein the battery includes the composite solid-state electrolyte membrane described in the present invention or the composite solid-state electrolyte membrane obtained by the preparation method described in the present invention.

[0112] In some specific embodiments, the solid-state battery of the present invention includes a positive electrode, a negative electrode, and the composite solid-state electrolyte membrane described in the present invention; specifically, the composite solid-state electrolyte membrane is located between the positive electrode and the negative electrode. The positive electrode material of the solid-state battery can be selected from: high-nickel ternary materials (such as NCM811), lithium-rich manganese-based materials, etc. The negative electrode material of the solid-state battery can be selected from: silicon-carbon negative electrode, lithium metal negative electrode, etc.

[0113] In some specific implementations, the solid-state battery of the present invention is a power battery for transportation vehicles, a battery for personal consumer electronics, or an energy storage battery for energy storage systems.

[0114] Fourth aspect

[0115] The present invention also provides an electrical device, wherein the device includes the solid-state battery described herein.

[0116] In some specific implementations, the solid-state battery described in this invention serves as the power supply for the electrical device.

[0117] In some specific implementation schemes, the electrical device may be selected from: personal consumer electronic products such as mobile phones and computers; transportation devices such as automobiles, trains, and airplanes; and energy storage systems such as wind, water, and solar energy.

[0118] Example

[0119] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0120] Preparation of LLZO precursor solution in the examples:

[0121] 4.41 g lithium nitrate, 9.75 g lanthanum nitrate, 0.42 g aluminum nitrate, and 4.62 g zirconium oxynitrate were dissolved in 100 mL of 15% glacial acetic acid in DMF solution to obtain an LLZO precursor solution.

[0122] In this embodiment, the equipment process parameters for electrospinning are as follows: voltage 20 KV; extrusion speed 0.3 mL / h; needle diameter 0.4 mm.

[0123] Example 1

[0124] (1) Preparation of TiO2 fibers by electrospinning: 15 g of titanium isopropoxide was dissolved in 100 mL of DMF and 25 mL of acetic acid was added. Then 5.5 g of PVA was added to form a spinning solution. Electrospinning was performed to obtain nanofibers. The nanofibers were then calcined at 600 °C for 1 h to form TiO2 fibers.

[0125] (2) The TiO2 fibers were immersed in an LLZO precursor solution, dried, and then calcined at 800°C for 1 hour in an argon atmosphere to form oxygen vacancies (Lewis acidic sites) and LLZO particles (Lewis basic sites) on the TiO2 surface, resulting in a size of 10 cm. A 10 cm composite nanofiber membrane. The composition of LLZO in the composite nanofiber membrane is: Li 6.4 Al 0.2 La3Zr2O 12 .

[0126] (3) Immerse a DMF solution containing 15% PEO and 1 mol / L LITFSI into the composite nanofiber membrane and allow it to dry to form a composite solid electrolyte membrane. The thickness of the composite solid electrolyte membrane is 40 μm, the TiO2 content is 46 wt%, and the LLZO content is 0.8 wt%.

[0127] Example 2

[0128] (1) Preparation of LLZO fibers by electrospinning: Take 50 g of LLZO precursor solution, add 5 g of PVP and stir to form an electrospinning solution. Obtain nanofibers by electrospinning, and then calcine at 800℃ for 5 h to form solid electrolyte LLZO fibers.

[0129] (2) The LLZO fibers were immersed in a 1 mol / L tetrabutyl titanate solution (solvent: 70% anhydrous ethanol: 30% glacial acetic acid, v:v), dried, and then calcined at 500℃ for 1 h in an argon atmosphere to form TiO2 (containing vacancy) sites on the surface of the LLZO fibers, resulting in a fiber size of 10 cm. A 10 cm composite nanofiber membrane. The composition of LLZO in the composite nanofiber membrane is: Li 6.4 Al 0.2 La3Zr2O 12 .

[0130] (3) Immerse a DMF solution containing 15% PEO and 1 mol / L LITFSI into the composite nanofiber membrane and allow it to dry to form a composite solid electrolyte membrane. The thickness of the composite solid electrolyte membrane is 40 μm, the TiO2 content is 0.8 wt%, and the LLZO content is 46 wt%.

[0131] Comparative Example 1

[0132] (1) TiO2 fibers were prepared by electrospinning (same as step (1) in Example 1).

[0133] (2) Then, the TiO2 fibers were placed in an argon atmosphere and calcined at 800℃ for 1 hour to form oxygen vacancies (Lewis acid sites) on the TiO2 surface, resulting in a size of 10 cm. 10 cm thick TiO2 nanofiber membrane.

[0134] (3) Immerse the nanofiber membrane in a DMF solution containing 15% PEO and 1 mol / L LITFSI, and allow it to dry to form a solid electrolyte membrane. The thickness of the solid electrolyte membrane is 40 μm, and the TiO2 content is 46 wt%.

[0135] Comparative Example 2

[0136] (1) TiO2 fibers were prepared by electrospinning (same as step (1) in Example 1).

[0137] (2) Then, the TiO2 fibers were calcined in air at 500-600℃ for 1 hour to obtain a size of 10 cm. 10 cm thick TiO2 nanofiber membrane.

[0138] (3) Immerse a DMF solution containing 15% PEO and 1 mol / L LITFSI into a TiO2 nanofiber membrane and allow it to dry to form a solid electrolyte membrane. The thickness of the solid electrolyte membrane is 40 μm and the TiO2 content is 46 wt%.

[0139] Comparative Example 3

[0140] (1) LLZO nanofibers were prepared by electrospinning (same as step (1) in Example 2).

[0141] (2) LLZO nanofibers were calcined at 800°C for 1 hour in air to obtain nanofibers with a size of 10 cm. 10 cm LLZO nanofiber membrane.

[0142] (3) Immerse a DMF solution containing 15% PEO and 1 mol / L LITFSI into an LLZO nanofiber membrane and allow it to dry to form a solid electrolyte membrane. The thickness of the solid electrolyte membrane is 40 μm and the LLZO content is 46 wt%.

[0143] Comparative Example 4

[0144] (1) TiO2 fibers were prepared by electrospinning (same as step (1) in Example 1).

[0145] (2) Then, the TiO2 fibers were calcined in air at 500-600℃ for 1 hour to obtain a size of 10 cm. 10 cm thick TiO2 nanofiber membrane.

[0146] (3) Immerse a TiO2 nanofiber membrane in a DMF solution containing 15% PEO, 0.8 wt% LLZO nanopowder (with the same composition as LLZO in Example 1), and 0.1 mol / L LiTFSI, and allow it to dry to form a composite solid electrolyte membrane. The thickness of the composite solid electrolyte membrane is 40 μm, and the TiO2 content is 46 wt%.

[0147] Test method:

[0148] The formed composite solid electrolyte membrane or solid electrolyte membrane is cut into R14 discs. A symmetrical cell with a blocking electrode (steel sheet) is assembled in a glove box, and its impedance is tested. The ionic conductivity is obtained by the following formula: σ = L / S·R, where L is the membrane thickness, S is the membrane area, and R is the membrane impedance (generally taken as the intersection with the Z' axis). Test conditions: room temperature 25℃; humidity 50%; test frequency range 10MHz-100Hz.

[0149] Test results:

[0150]

[0151] In Example 1, based on the preparation of TiO2 nanofibers, Lewis basic sites (LLZO particles) were introduced, resulting in a composite solid electrolyte membrane that simultaneously possesses Lewis acidic and Lewis basic sites, exhibiting high ionic conductivity. In contrast, Comparative Examples 1 and 2 only prepared TiO2 nanofibers, and the resulting solid electrolyte membranes only contained Lewis acidic sites, resulting in low ionic conductivity.

[0152] Example 2, based on the preparation of LLZO nanofibers, introduced Lewis acid sites (TiO2 oxygen vacancies), resulting in a composite solid electrolyte membrane with both Lewis acid sites and Lewis basic sites, exhibiting high ionic conductivity; while Comparative Example 3, which only prepared LLZO nanofibers, resulted in a solid electrolyte membrane containing only Lewis basic sites, exhibiting low ionic conductivity.

[0153] In Comparative Example 4, TiO2 fiber skeletons were immersed in LLZO nanoparticles dispersed in PEO, and the resulting solid electrolyte membrane had a lower conductivity than that of Example 1.

[0154] As can be seen from the above test results, compared with solid electrolyte membranes containing only a single Lewis acidic site or Lewis basic site, the composite solid electrolyte membrane of the present invention, which has both Lewis acidic sites and Lewis basic sites, has a higher ionic conductivity.

[0155] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0156] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A composite solid electrolyte membrane, characterized in that, The composite solid electrolyte membrane comprises a nanofiber support membrane, a polymer electrolyte, and a lithium salt. The nanofiber support membrane comprises a first oxide and a second oxide different from the first oxide. The first oxide has Lewis acid sites, and the second oxide has Lewis base sites. The Lewis acid sites are at least partially provided by defective TiO2, and the Lewis base sites are at least partially provided by LLZO-based oxides. The LLZO-based oxides include one or more of undoped LLZO and LLZO doped with other metals. Furthermore, the total content of the first oxide and the second oxide, based on the total mass of the composite solid electrolyte membrane, is 30%-60% by mass. The method for preparing the nanofiber supported membrane includes: S1： S1a) Prepare the first oxide matrix fiber by electrospinning, and then immerse the first oxide matrix fiber in the second oxide precursor solution; or, S1b) The second oxide matrix fiber is prepared by electrospinning, and then the second oxide matrix fiber is immersed in the first oxide precursor solution; S2: Drying and calcining to obtain the nanofiber support membrane.

2. The composite solid electrolyte membrane according to claim 1, characterized in that, The nanofiber support membrane comprises a matrix fiber formed of the first oxide and second oxide particles formed on at least a portion of the surface of the matrix fiber; or, the nanofiber support membrane comprises a matrix fiber formed of the second oxide and first oxide particles formed on at least a portion of the surface of the matrix fiber.

3. The composite solid electrolyte membrane according to claim 1 or 2, characterized in that, The first oxide is formed from the defective TiO2, and the second oxide is formed from an LLZO-based oxide.

4. The composite solid electrolyte membrane according to claim 1 or 2, characterized in that, The LLZO-based oxides are also doped with one or more of the following elements: aluminum, niobium, tantalum, zirconium, and gallium.

5. The composite solid electrolyte membrane according to claim 1 or 2, characterized in that, The composite solid electrolyte membrane has one or more of the following characteristics: The composite solid electrolyte membrane exhibits an ionic conductivity of over 0.7 mS / cm under conditions of room temperature (25°C) and humidity (50%). The thickness of the composite solid electrolyte membrane is 20-50 μm.

6. A method for preparing a composite solid electrolyte membrane according to any one of claims 1-5, characterized in that, The preparation method includes: S1： S1a) Prepare a first oxide matrix fiber by electrospinning, and then immerse the first oxide matrix fiber in a second oxide precursor solution; or... S1b) The second oxide matrix fiber is prepared by electrospinning, and then the second oxide matrix fiber is immersed in the first oxide precursor solution; S2: Drying and calcining to obtain the nanofiber supported membrane; S3: Immerse the polymer electrolyte and lithium salt in the nanofiber support membrane obtained in step S2, and dry to obtain the composite solid electrolyte membrane.

7. The preparation method according to claim 6, characterized in that, The first oxide is defective TiO2, and the precursor of the defective TiO2 includes at least one of tetrabutyl titanate, titanium isopropoxide, and nano-TiO2; the second oxide is an LLZO-based oxide, and the precursor of the LLZO-based oxide includes a soluble lithium source, a lanthanum source, an aluminum source, and a zirconium source.

8. The preparation method according to claim 6 or 7, characterized in that, In step S2, the calcination temperature is 500-1000℃.

9. A solid-state battery, characterized in that, It includes the composite solid electrolyte membrane according to any one of claims 1-5 or the composite solid electrolyte membrane obtained by the preparation method according to any one of claims 6-8.

10. The solid-state battery according to claim 9, characterized in that, The solid-state battery is a power battery for transportation vehicles, a battery for personal consumer electronics, or an energy storage battery for energy storage systems.

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