Solid electrolyte membrane and preparation method and application thereof

Abstract

The invention discloses a solid electrolyte membrane and a preparation method and application thereof. The solid electrolyte membrane comprises a first electrolyte close to the positive pole piece and a second electrolyte layer close to the negative pole piece. The first electrolyte layer comprises a polymer, a lithium salt and an additive, and the second electrolyte layer comprises a solid electrolyte, a polymer, a lithium salt and an additive. The first electrolyte layer has a wide electrochemical window and relatively high mechanical properties, and can be matched with a high-voltage positive electrode material and improve solid-solid interface contact. The solid electrolyte of the second electrolyte layer is mainly composed of a continuous vertical array micro-mesoporous material, has a micro-mesoporous structure and high surface adsorption energy, and can accelerate lithium salt dissociation, reduce molecular interaction between polymer chains, form a three-dimensional continuous fast ion transmission channel and a heat conduction network, and improve ionic conductivity and safety performance. The solid electrolyte membrane disclosed by the invention has excellent ionic conductivity, wide electrochemical window, high safety performance and excellent electrochemical performance.

Description

Technical Field

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

[0002] As the development of traditional lithium-ion battery systems has reached a bottleneck, the innovation of battery technology has become increasingly urgent. Among them, solid-state batteries have higher energy density and safety performance and are generally considered to be an important development direction for the next generation of battery technology.

[0003] The solid electrolyte membrane is located between the positive and negative electrodes, and needs to have high ionic conductivity, high interface compatibility and high safety to meet the development needs of solid-state batteries. Pure polymer solid electrolytes have a narrow electrochemical window, low ionic conductivity, low thermal conductivity and poor safety performance, which seriously restrict the development of solid-state batteries. To this end, some technologies combine polymers and nanofillers to reduce the local crystallinity of the polymer and improve the electrochemical window and ionic conductivity. However, due to the size effect, nanofillers are prone to agglomeration in the polymer, making it difficult to form a continuous ion transport channel and thermal conductivity network, resulting in inconsistent reaction rates in various parts of the battery, increasing battery polarization, and limited improvements in electrochemical performance and safety performance. Summary of the invention

[0004] In order to solve the problems of the prior art, the present invention provides a solid electrolyte membrane and a preparation method and application thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In order to solve the above problems, an embodiment of the present application provides a solid electrolyte membrane and a method for preparing the same.

[0007] In a first aspect, the present application provides a solid electrolyte membrane, comprising a first electrolyte layer close to a positive electrode plate and a second electrolyte layer close to a negative electrode plate.

[0008] The first electrolyte layer is composed of a polymer, a lithium salt and an additive, and includes the following components:

[0009] Polymer, 80.0-92.5wt%;

[0010] Lithium salt, 5-15.0wt%;

[0011] Additives, 2.5-5wt%.

[0012] The second electrolyte layer is composed of a vertical array of micro-mesoporous materials, polymers, lithium salts and additives, including the following components:

[0013] Micro-mesoporous material, 40-60wt%;

[0014] Polymer, 32.5-40 wt%;

[0015] Lithium salt, 5-15.0wt%;

[0016] Additives, 2.5-5wt%.

[0017] The thickness h1 of the first electrolyte layer and the thickness h2 of the second electrolyte layer must satisfy 10≤h2+h1≤100 μm;

[0018] First, the introduction of vertical array micro-mesoporous materials enables the second electrolyte layer to have a continuous micro-mesoporous structure, abundant Lewis acid sites and high surface adsorption energy, which can fix the anions in the lithium salt and form a continuous ion transmission channel and a three-dimensional thermal conductive network perpendicular to the positive and negative electrode sheets, which can significantly improve the ionic conductivity and safety performance. Secondly, the introduction of polymers and additives enables the first electrolyte layer to have high mechanical stability and a wide electrochemical window, which can significantly improve the solid-solid interface contact between the positive electrode sheet and the solid electrolyte and reduce the interface impedance. Through this vertical array structure and double-layer electrolyte layer design, ionic conductivity, wide electrochemical window and high safety performance can be taken into account, thereby significantly improving battery performance.

[0019] In some exemplary embodiments, the micro-mesoporous material includes at least one of molecular sieves, MOF, ZIF, COF, and UiO series.

[0020] In some exemplary embodiments, the micro-mesoporous material has an average particle size of 50 to 2000 nm, an average pore size of 0.1 to 10 nm, and an average specific surface area of ​​500 to 1500 m 2 g -1 .

[0021] In some exemplary embodiments, the vertical array of micro-mesoporous materials has a diameter of 0.1-5 μm, and a length L thereof needs to satisfy 1≤h2 / L≤1.5 and 2≤L / h1≤5.

[0022] In some exemplary embodiments, the polymer includes at least one of polytetrafluoroethylene and polyethylene oxide.

[0023] In some exemplary embodiments, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide.

[0024] In some exemplary embodiments, the additive includes at least one of trimethyl phosphate, ethyl hexafluorophosphate, vinyl sulfate, and terephthalonitrile.

[0025] First, by regulating the particle size, pore size and specific surface area of ​​the micro-mesoporous material, the electrochemical performance and processing performance of the solid electrolyte membrane can be taken into account. Under the premise of ensuring the processing performance, more lithium salt anions can be confined. Secondly, the composite method of the micro-mesoporous material and the polymer is regulated, and the polymer is compounded between the micro-mesoporous materials of the vertical array frame to construct a continuous ion transmission channel and a thermal conductive network. Finally, the vertical array length of the micro-mesoporous material is regulated, and the thickness of the first electrolyte layer and the second electrolyte layer are balanced to form a shorter ion fast transmission channel and an excellent three-dimensional thermal conductive network, which can significantly improve the ionic conductivity and thermal conductivity, and exhibit excellent electrochemical performance and safety performance when used in secondary batteries.

[0026] In a second aspect, the present application provides a method for preparing a solid electrolyte membrane, comprising:

[0027] Preparation of vertical array micro-mesoporous materials: With the help of array framework structures such as templates, immerse them in a precursor solution of micro-mesoporous materials, control the reaction temperature and time, induce them to crystallize and grow along the framework structure, and finally form a continuous three-dimensional vertical array structure in situ;

[0028] Film forming treatment: the polymer, lithium salt and additive are dissolved in an organic solvent in a certain proportion, mixed and dispersed evenly, and coated on the surface of the micro-mesoporous material, and dried to obtain a second blank. Similarly, the polymer, lithium salt and additive are mixed evenly in a certain proportion, and coated on the surface of the second blank to obtain a first blank; the coating method includes at least one of scraping, spin coating, casting, and tape coating.

[0029] Calendering treatment: Calendering the electrolyte layer composed of the first blank and the second blank to obtain a solid electrolyte membrane;

[0030] In a third aspect, the lithium-ion battery described in the present application includes a positive electrode, a negative electrode and a solid electrolyte membrane located between the positive electrode and the negative electrode, and the solid electrolyte membrane is the solid electrolyte membrane described above.

[0031] Compared with the prior art, the beneficial effects of the invention are as follows: the present application discloses a solid electrolyte membrane and a preparation method thereof. The solid electrolyte membrane includes a first electrolyte close to the positive electrode sheet and a second electrolyte layer close to the negative electrode sheet. The first electrolyte layer includes a polymer, a lithium salt and an additive, and the second electrolyte layer includes a solid electrolyte, a polymer, a lithium salt and an additive in a vertical array structure. The first electrolyte layer has a wide electrochemical window and high mechanical properties, can match high-voltage positive electrode materials and improve solid-solid interface contact. The solid electrolyte of the second electrolyte layer is composed of a vertical array of micro-mesoporous materials, has a micro-mesoporous structure and high surface adsorption energy, and can accelerate the dissociation of lithium salts. Through this vertical array structure design, the present application can effectively improve the filler agglomeration problem of polymer solid electrolytes, confine lithium salts, form continuous and fast transmission channels and three-dimensional thermal conductive networks, and significantly improve ionic conductivity and safety performance. Secondly, the present application has high ionic conductivity, wide electrochemical window and high safety performance through a double electrolyte layer design, and exhibits excellent electrochemical performance and safety performance when used in secondary batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objectives and advantages of the present invention will become more apparent from a reading of the detailed description of non-limiting embodiments made with reference to the following accompanying drawings.

[0033] Figure 1 It is a schematic diagram of the structure of a lithium-ion battery solid electrolyte membrane provided in an embodiment of the present application;

[0034] Figure 2 This is a performance test result table of the solid electrolyte membrane and lithium ion battery of the embodiments of the present application and the comparison. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below by examples, which are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0036] A solid electrolyte membrane comprises a first electrolyte layer close to a positive electrode plate and a second electrolyte layer close to a negative electrode plate;

[0037] The first electrolyte layer is composed of a polymer, a lithium salt and an additive, and includes the following components:

[0038] Polymer, 80.0-92.5wt%;

[0039] Lithium salt, 5-15.0wt%;

[0040] Additives, 2.5-5wt%.

[0041] The second electrolyte layer is composed of a vertical array of micro-mesoporous materials, polymers, lithium salts and additives, including the following components:

[0042] Micro-mesoporous material, 40-60wt%;

[0043] Polymer, 32.5-40 wt%;

[0044] Lithium salt, 5-15.0wt%;

[0045] Additives, 2.5-5wt%.

[0046] The thickness h1 of the first electrolyte layer and the thickness h2 of the second electrolyte layer must satisfy 10≤h1+h2≤100 μm;

[0047] The vertical array of micro-mesoporous materials is attached to the defects of the vertical template frame, nucleates and grows continuously, and finally wraps on its surface to form a three-dimensional array structure perpendicular to the positive and negative pole pieces, with a diameter of 0.01 to 10 μm, preferably 0.1 to 5 μm. Its length L needs to satisfy 1≤h2 / L≤1.5 and 2≤L / h1≤5.

[0048] The micro-mesoporous material includes at least one of molecular sieve, MOF, ZIF, COF, and UiO series;

[0049] The micro-mesoporous material has an average particle size of 50 to 2000 nm, an average pore size of 0.1 to 20 nm, preferably 0.1 to 10 nm, and an average specific surface area of ​​200 to 3000 m 2 g -1 , preferably 500~1500m 2 g -1 .

[0050] The polymer includes at least one of polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, polyethylene oxide, and polyimide.

[0051] The lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium tetrafluoroborate, and lithium bis(oxalatoborate).

[0052] The additive includes at least one of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, trimethyl phosphate, ethyl hexafluorophosphate, vinyl sulfate, terephthalonitrile, and p-dimethylbenzoic acid.

[0053] The molecular sieve includes at least one of 3A, 4A, 5A, ZSM-5, 10X, 13X, MIL-100, and MIL-101 molecular sieves;

[0054] The MOF series includes at least one of MOF-2, MOF-4, MOF-5, MOF-74, MOF-177, MOF-199, MOF-303, MOF-525, MOF-801, MOF-808, and MOF-867;

[0055] The ZIF series includes ZIF-2, ZIF-3, ZIF-4, ZIF-5, ZIF-6, ZIF-67, ZIF-7, ZIF-8, ZIF-9, ZIF-10, ZIF-11 , at least one of ZIF-12, ZIF-14, ZIF-20, ZIF-23, ZIF-60, ZIF-68, ZIF-69, ZIF-70, ZIF-95, and ZIF-100;

[0056] The COF series includes at least one of COF-1, COF-2, COF-3, COF-4, COF-5, COF-6, COF-7, COF-8, COF-9, COF-10, COF-42, COF-102, COF-103, COF-105, COF-108, and COF-300;

[0057] The UiO series includes at least one of UiO-66, UiO-67 and UiO-68.

[0058] A method for preparing a solid electrolyte membrane comprises the following steps:

[0059] Preparation of vertical array micro-mesoporous materials: With the help of a framework structure such as a template, immerse it in a precursor solution of the micro-mesoporous material in a certain proportion, control the reaction conditions, induce it to grow along the framework structure, and form a continuous three-dimensional vertical array structure;

[0060] Film forming treatment: dissolving the polymer, lithium salt and additive in an organic solvent in a certain proportion, mixing and dispersing them uniformly, and coating them on the surface of the micro-mesoporous material, and obtaining a second blank after drying; similarly, mixing the polymer, lithium salt and additive in a certain proportion, and coating them on the surface of the second blank to obtain a first blank;

[0061] Calendering treatment: Calendering the electrolyte layer composed of the first blank and the second blank to obtain a solid electrolyte membrane.

[0062] The template agent includes at least one of alumina hollow fiber, graphene, carbon nanotube, triethylamine, di-n-propylamine, diisopropylamine, glass fiber, polyimide fiber and carbon cloth.

[0063] In the method for preparing the solid electrolyte membrane, the organic solvent comprises at least one of methanol, ethanol, isopropanol, acetonitrile, N,N-dimethylformamide, N,N-dimethylpyrrolidone, dimethyl sulfoxide, dimethyl carbonate, diethyl carbonate, and ethylene carbonate;

[0064] The film forming treatment method includes at least one of blade coating, spray coating, spin coating, casting and pouring.

[0065] The solid electrolyte membrane can be applied to electrochemical devices such as liquid lithium-ion batteries, solid-state batteries and lithium metal batteries, and will play an important role in consumer electronics, electric vehicles, energy storage systems and low-altitude flight.

[0066] The present application also provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode, a negative electrode and a solid electrolyte membrane located between the positive electrode and the negative electrode, the solid electrolyte membrane being the solid electrolyte membrane described above. The preparation method comprises the following steps:

[0067] S1. Preparation of positive electrode sheet: Dissolve the positive electrode material lithium iron phosphate, conductive agent Super P, and binder polyvinylidene fluoride in N-methylpyrrolidone at a mass ratio of 96.5:1.5:2, mix well, apply on aluminum foil, dry and roll to 2.4g / cm 3 Compacted density positive electrode sheet;

[0068] S2. Preparation of negative electrode sheet: artificial graphite, conductive agent Super P, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose were mixed and dissolved in deionized water in a mass ratio of 95:1:2:2, mixed evenly, coated on copper foil, dried, and rolled into 1.55 g / cm 3 Compacted density negative electrode sheet;

[0069] S3, preparing a solid electrolyte membrane: the specific scheme is shown in the following embodiment;

[0070] S4, battery assembly: stacking the positive electrode, solid electrolyte membrane and negative electrode, wherein the solid electrolyte membrane is the solid electrolyte membrane according to claims 1 to 10;

[0071] Ionic conductivity testing, electrochemical window, electrochemical performance and thermal conductivity testing include the following steps:

[0072] S1. Ionic conductivity test: Using the AC impedance method, the solid electrolyte membrane is sandwiched between two stainless steel discs and assembled into a button cell. It is pre-heat treated at 60°C for 2 hours to improve the interface contact between the electrolyte and the electrode. Then connect the electrochemical workstation, apply a voltage amplitude of 10mV, and the test frequency range is 1MHz~1Hz. Measure the response current to obtain the corresponding impedance value R. Use a spiral micrometer to measure the thickness H of the solid electrolyte membrane at more than 10 different positions and take the average value. Taking the area of ​​the stainless steel sheet as S, according to the formula σ=H / (R*S), the ionic conductivity of the solid electrolyte membrane can be obtained.

[0073] S2. Electrochemical window test: Linear sweep voltammetry was used for testing, with a sweep voltage range of 2 to 6 V and a sweep rate of 5 mV S -1 , evaluating the electrochemical stability window of solid electrolyte membranes.

[0074] S3. Electrochemical performance test: Using the Xinwei test system, the assembled battery was charged and discharged at a constant current and constant voltage of 0.5C at room temperature (25°C), and its cycle performance was tested, and the number of cycles when the discharge capacity retention rate was 80% was recorded.

[0075] S4. Thermal conductivity test: Using laser flash diffusivity, the solid electrolyte membrane is placed on a horizontal fixture and an instantaneous laser pulse is applied. The heat generated is transferred to its upper surface through the sample. An infrared detector is used to monitor the temperature of the upper surface of the sample and obtain the temperature rise curve. The final thermal conductivity is then obtained based on the corresponding fitting model.

[0076] Now, exemplary embodiments according to the present application will be described in more detail with reference to the drawings.

[0077] The first aspect of the present application provides a solid electrolyte membrane, which is composed of the first electrolyte close to the positive electrode and the second electrolyte layer close to the negative electrode, wherein the second electrolyte layer comprises a vertical array of micro-mesoporous materials, as shown in detail. Figure 1 .

[0078] Example 1

[0079] Preparation of vertical array micro-mesoporous material: 0.5g alumina hollow fiber array is immersed in 0.8mol / L dimethylimidazole solution, activated at 60℃ for 12h, and a large number of functional groups and active sites are induced on the surface of the template. Then the fiber array is immersed in 0.2mol / L zinc nitrate precursor solution, 0.8mol / L dimethylimidazole solution is added to the zinc solution under stirring at room temperature, hydrothermally reacted at 60℃ for 6h, filtered and dried to obtain a vertical array micro-mesoporous material, the length of which can be controlled by controlling the length of the alumina fiber array. The length of the micro-mesoporous material in Example 1 is 10μm.

[0080] Film forming treatment: The polytetrafluoroethylene, lithium bis(trifluoromethanesulfonyl imide) and trimethyl phosphate are dissolved in N,N-dimethylformamide solution in a certain mass ratio, mixed and dispersed evenly, and cast on the surface of the micro-mesoporous material (the mass ratio of micro-mesoporous material, polymer, lithium salt and additive is 50:35:12:3), and dried to obtain the second blank. Similarly, polytetrafluoroethylene, lithium bis(trifluoromethanesulfonyl imide) and trimethyl phosphate are mixed evenly in a mass ratio of 85:12:3, and scraped on the surface of the second blank to obtain the first blank.

[0081] Calendering treatment: Calendering the electrolyte layer composed of the first blank and the second blank at a pressure of 5t to obtain a solid electrolyte membrane; it is obvious that the thickness of the first / second electrolyte membrane layer can be achieved by controlling the relevant coating process and calendering process. In this example, the thickness of the first electrolyte membrane is 5μm, and the thickness of the second electrolyte membrane is 10μm.

[0082] Example 2

[0083] The main differences from Example 1 include: the thickness of the first electrolyte membrane is 4 μm, and the thickness of the second electrolyte membrane is 12.5 μm.

[0084] Example 3

[0085] The main differences from Example 1 include: the thickness of the first electrolyte membrane is 2.5 μm, and the thickness of the second electrolyte membrane is 15 μm.

[0086] Example 4

[0087] The main differences from Example 1 include:

[0088] Preparation of vertical array micro-mesoporous material: The zinc nitrate solution was replaced with a cobalt nitrate solution, and the length of the micro-mesoporous material was regulated by controlling the length of the alumina fiber array. The length of the micro-mesoporous material in Example 4 was 16 μm.

[0089] In addition, the thickness of the first electrolyte membrane is 8 μm, and the thickness of the second electrolyte membrane is 16 μm.

[0090] Example 5

[0091] The main differences from Example 4 include: the thickness of the first electrolyte membrane is 6.4 μm, and the thickness of the second electrolyte membrane is 20 μm.

[0092] Example 6

[0093] The main differences from Example 4 include: the thickness of the first electrolyte membrane is 4 μm, and the thickness of the second electrolyte membrane is 24 μm.

[0094] Example 7

[0095] The main differences from Example 1 include:

[0096] Preparation of vertical array micro-mesoporous material: 0.5g of alumina hollow fiber array was immersed in 0.3mol / L terephthalic acid solution and activated at 60°C for 12h. Then the fiber array was immersed in 0.3mol / L zirconium chloride precursor solution, 0.8mol / L terephthalic acid solution was added to the zirconium solution under room temperature stirring, hydrothermally reacted at 120°C for 24h, filtered and dried to obtain a vertical array micro-mesoporous material, the length of which can be controlled by controlling the length of the alumina fiber array. The length of the micro-mesoporous material in Example 1 is 20μm.

[0097] In addition, the thickness of the first electrolyte membrane is 10 μm, and the thickness of the second electrolyte membrane is 20 μm.

[0098] Example 8

[0099] The main differences from Example 7 include: the thickness of the first electrolyte membrane is 8 μm, and the thickness of the second electrolyte membrane is 25 μm.

[0100] Example 9

[0101] The main differences from Example 7 include: the thickness of the first electrolyte membrane is 5 μm, and the thickness of the second electrolyte membrane is 30 μm.

[0102] Comparative Example 1

[0103] The main differences between Comparative Example 1 and Example 1 include: no vertical array of micro-mesoporous material, polytetrafluoroethylene, lithium bis(trifluoromethanesulfonyl)imide and trimethyl phosphate are uniformly mixed in a mass ratio of 85:12:3 and directly coated into a solid electrolyte membrane with a thickness of 15 μm.

[0104] Comparative Example 2

[0105] The main differences between Comparative Example 2 and Example 1 include: conventional ZIF-8 powder (particle size, pore size and specific surface area all meet the requirements of the micro-mesoporous material described in this application) is evenly mixed with polymer, lithium salt and additive in a mass ratio of 50:35:12:3, and coated into a solid electrolyte membrane with a thickness of 10 μm.

[0106] Comparative Example 3

[0107] The main differences between Comparative Example 3 and Example 1 include: the length of the three-dimensional vertical array structure of the micro-mesoporous material is 5 μm, which does not satisfy 1≤h2 / L≤1.5 and 2≤L / h1≤5.

[0108] Comparative Example 4

[0109] The main differences between Comparative Example 4 and Example 1 include: only the second electrolyte layer is included, and the first electrolyte layer is not included.

[0110] The main differences between Examples 1-9 and Comparative Examples 1-4 are shown in Figure 2 .

[0111] From the results of Examples 1 to 9 and Comparative Examples 1 to 4 above, it can be seen that the ionic conductivity of the pure polymer system is low, lithium ions can only move slowly along the polymer chain, and the electrochemical window is narrow, it is easily oxidized under high voltage, has poor chemical stability, and poor cycle performance. In addition, the amorphous structure and vibration of the macromolecular chain in the polymer make it have extremely low thermal conductivity, which easily causes thermal inhomogeneity and heat accumulation of the solid electrolyte membrane during the charge and discharge process, exacerbating the electrode side reaction and the uneven deposition of lithium dendrites.

[0112] When polymers are composited with micro-mesoporous materials, the entanglement and interaction between polymer molecular chains can be reduced, and their ionic conductivity and thermal conductivity can be improved. However, when its content is low, the polymer is a continuous phase, and the micro-mesoporous materials exist in isolation in the polymer matrix, and are not connected to each other, forming a "sea-island" structure, which has a low contribution to improving the thermal conductivity of the polymer; when the content increases, the micro-mesoporous materials contact each other, forming a local thermal conductive chain or thermal conductive network, and the thermal conductivity of the system is significantly increased. Therefore, the ionic conductivity, electrochemical window and thermal conductivity of polymer electrolytes composited with micro-mesoporous materials can be further improved, but inorganic fillers are prone to agglomeration, and the cycle performance is still poor, which is difficult to meet actual needs.

[0113] Furthermore, constructing a vertical array of micro-mesoporous material composite polymer electrolytes can further improve electrochemical performance and safety performance. When constructing a continuous micro-mesoporous material channel, its heat conduction chains are interconnected to form a heat conduction network that runs through the entire system. The heat flow is transmitted along the continuous three-dimensional array structure, the phonon scattering is small, and the thermal conductivity of the composite electrolyte is significantly improved. However, its continuous transmission channel is short, and the performance improvement is limited. In addition, the single first electrolyte layer has low ionic conductivity and thermal conductivity, and poor cycle performance and safety performance. The single second electrolyte layer has poor solid-solid interface contact and low cycle performance, which are difficult to meet actual needs.

[0114] Finally, the present application constructs a continuous, appropriately lengthed, vertical array of micro-mesoporous materials composite polymer solid electrolytes with short fast ion transport channels and three-dimensional thermal conductive networks, which can significantly improve ionic conductivity, electrochemical window and safety performance. The present application can combine high ionic conductivity, wide electrochemical window and high safety performance through a double electrolyte layer design, and exhibits excellent electrochemical performance and safety performance when used in secondary batteries.

[0115] The present application discloses a solid electrolyte membrane and a method for preparing the same. The solid electrolyte membrane includes a first electrolyte close to the positive electrode and a second electrolyte layer close to the negative electrode. The first electrolyte layer includes a polymer, a lithium salt and an additive, and the second electrolyte layer includes a solid electrolyte, a polymer, a lithium salt and an additive in a vertical array structure. The first electrolyte layer has a high voltage electrochemical window and can match high voltage positive electrode materials. The solid electrolyte of the second electrolyte layer is composed of a vertical array of micro-mesoporous materials, which has a micro-mesoporous structure and high surface adsorption energy, and can accelerate the dissociation of lithium salts. Through this vertical array structure design, the present application can effectively improve the filler agglomeration problem of polymer solid electrolytes, confine the anions in the lithium salt and reduce the molecular interaction between polymer chains, form a continuous and fast ion transmission channel and a three-dimensional thermal conductive network, and can significantly improve the ionic conductivity and safety performance. Secondly, the present application has high ionic conductivity, wide electrochemical window and high safety performance through a double electrolyte layer design, and exhibits excellent electrochemical performance and safety performance when used in secondary batteries.

[0116] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A solid electrolyte membrane, characterized in that: including a first electrolyte layer close to the positive electrode sheet and a second electrolyte layer close to the negative electrode sheet; The first electrolyte layer is composed of a polymer, a lithium salt and an additive, and includes the following components: Polymer, 80.0-92.5wt%; Lithium salt, 5-15.0wt%; Additives, 2.5-5wt%; The second electrolyte layer is composed of a vertical array of micro-mesoporous materials, polymers, lithium salts and additives, including the following components: Micro-mesoporous material, 40-60wt%; Polymer, 32.5-40 wt%; Lithium salt, 5-15.0wt%; Additives, 2.5-5wt%; The thickness h1 of the first electrolyte layer and the thickness h2 of the second electrolyte layer must satisfy 10≤h1+h2≤100 μm; The vertical array of micro-mesoporous materials is attached to the defects of the vertical template frame, nucleates and grows continuously, and finally wraps around its surface to form a three-dimensional array structure perpendicular to the positive and negative pole pieces, with a diameter of 0.01 to 10 μm, and its length L needs to satisfy 1≤h2 / L≤1.5 and 2≤L / h1≤5.

2. The solid electrolyte membrane according to claim 1, characterized in that The micro-mesoporous material includes at least one of molecular sieve, MOF, ZIF, COF, and UiO series; The micro-mesoporous material has an average particle size of 50 to 2000 nm, an average pore size of 0.1 to 20 nm, and an average specific surface area of ​​200 to 3000 m 2 g -1 . 3 . The solid electrolyte membrane according to claim 1 , wherein the polymer comprises at least one of polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, polyethylene oxide, and polyimide.

4. The solid electrolyte membrane according to claim 1, wherein the lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium tetrafluoroborate, and lithium bis(oxalatoborate).

5. The solid electrolyte membrane according to claim 1, wherein the additive comprises at least one of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, trimethyl phosphate, ethyl hexafluorophosphate, vinyl sulfate, terephthalonitrile, and p-dimethylbenzoic acid.

6. The solid electrolyte membrane according to claim 2, wherein the molecular sieve comprises at least one of 3A, 4A, 5A, ZSM-5, 10X, 13X, MIL-100, and MIL-101 molecular sieves; MOF series, including at least one of MOF-2, MOF-4, MOF-5, MOF-74, MOF-177, MOF-199, MOF-303, MOF-525, MOF-801, MOF-808, and MOF-867; ZIF series, including ZIF-2, ZIF-3, ZIF-4, ZIF-5, ZIF-6, ZIF-67, ZIF-7, ZIF-8, ZIF-9, ZIF-10, ZIF-11, At least one of ZIF-12, ZIF-14, ZIF-20, ZIF-23, ZIF-60, ZIF-68, ZIF-69, ZIF-70, ZIF-95, and ZIF-100; COF series, including at least one of COF-1, COF-2, COF-3, COF-4, COF-5, COF-6, COF-7, COF-8, COF-9, COF-10, COF-42, COF-102, COF-103, COF-105, COF-108, and COF-300; The UiO series includes at least one of UiO-66, UiO-67 and UiO-68.

7. A method for preparing a solid electrolyte membrane, characterized in that: The steps include: Preparation of vertical array micro-mesoporous materials: With the help of a framework structure such as a template, immerse it in a precursor solution of the micro-mesoporous material in a certain proportion, control the reaction conditions, induce it to grow along the framework structure, and form a continuous three-dimensional vertical array structure; Film forming treatment: dissolving the polymer, lithium salt and additive in an organic solvent in a certain proportion, mixing and dispersing them uniformly, and coating them on the surface of the micro-mesoporous material, and obtaining a second blank after drying; similarly, mixing the polymer, lithium salt and additive in a certain proportion, and coating them on the surface of the second blank to obtain a first blank; Calendering treatment: Calendering the electrolyte layer composed of the first blank and the second blank to obtain a solid electrolyte membrane.

8. The method for preparing a solid electrolyte membrane according to claim 7, characterized in that: The template agent includes at least one of alumina hollow fiber, graphene, carbon nanotube, triethylamine, di-n-propylamine, diisopropylamine, glass fiber, polyimide fiber and carbon cloth.

9. The method for preparing a solid electrolyte membrane according to claim 7, wherein the organic solvent comprises at least one of methanol, ethanol, isopropanol, acetonitrile, N,N-dimethylformamide, N,N-dimethylpyrrolidone, dimethyl sulfoxide, dimethyl carbonate, diethyl carbonate, and ethylene carbonate; The film forming treatment method includes at least one method of blade coating, spray coating, spin coating, casting, and pouring.

10. The solid electrolyte membrane as described in any one of claims 1 to 9 can be applied to electrochemical devices such as liquid lithium-ion batteries, solid-state batteries and lithium metal batteries, and will play an important role in the fields of consumer electronics, electric vehicles, energy storage systems and low-altitude flight.

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