Composition, composite film, and use

Abstract

Provided are a composition, a composite film, and a use. The composition comprises a ceramic electrolyte and an ionic liquid, wherein the ionic liquid comprises a piperidine ionic liquid. The provided composition has high ionic conductivity.

Description

Compositions, composite films and applications

[0001] This application claims priority to Chinese Patent Application No. 202410506761.8, filed on April 25, 2024, entitled "Composition, Ceramic Electrolyte Thin Film and Preparation Method Thereof, Composite Thin Film and Application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and more particularly to a composition, composite film, and application. Background Technology

[0003] Lithium-ion batteries possess advantages such as high safety, high energy density, high voltage, and long cycle life, and are considered the most promising rechargeable batteries. Traditional lithium-ion batteries generally use organic electrolytes, but organic electrolytes pose safety hazards due to their flammability and explosiveness. Solid-state electrolytes, on the other hand, have high ionic conductivity, a wide electrochemical stability window, and excellent thermodynamic properties such as high strength and elastic modulus, and are widely used in lithium-ion batteries.

[0004] Solid electrolytes include ceramic electrolytes and polymer electrolytes. The rigidity of ceramic electrolytes makes it difficult to buffer the volume changes of electrode materials during cycling, resulting in a loss of close contact between the ceramic electrolyte and the electrode. The ionic conductivity of existing ceramic electrolytes is still relatively low and needs further improvement. Technical solutions

[0005] This application provides a composition, a composite film, and an application.

[0006] This application provides a composition comprising a ceramic electrolyte and an ionic liquid, wherein the ionic liquid comprises a piperidine-based ionic liquid.

[0007] In addition, a composite film includes a polymer electrolyte film and a ceramic electrolyte film stacked together, wherein the material of the ceramic electrolyte film includes the above-described composition.

[0008] Additionally, there is an electrochemical device, the material of which comprises the above-described composition.

[0009] Compared to existing technologies, the composition provided in this application has a higher ionic conductivity. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 is a schematic diagram of the structure of the composite film provided in an embodiment of this application;

[0012] Figure 2 is a flowchart of the preparation method of the ceramic electrolyte thin film provided in the embodiment of this application;

[0013] Figure 3 is a schematic diagram of the battery structure provided in an embodiment of this application.

[0014] Explanation of reference numerals in the attached figures: Composite film 10; Ceramic electrolyte film 11; Polymer electrolyte film 12; Battery 100; Positive electrode 20; Negative electrode 30.

[0015] Implementation methods of this application

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] This application provides composite materials, optoelectronic devices, and methods for fabricating the same. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order.

[0018] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0019] In this application, expressions such as "one or more" refer to one or more of the listed items. "Multiple" refers to any combination of two or more of these items, including any combination of a single item or a plurality of items. For example, "at least one of a, b or c" or "at least one of a, b and c" can both mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0020] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 0.04 to 0.1 has specifically disclosed sub-ranges, such as from 0.04 to 0.05, from 0.05 to 0.06, from 0.06 to 0.07, from 0.07 to 0.09, etc., and single numbers within the range, such as 0.04, 0.05, and 0.06, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0021] Ionic liquids, as a type of green solvent, possess advantages such as non-volatility, non-flammability, good thermal stability, chemical stability with solid electrolytes, and high ionic conductivity. They are often used as additives to improve the performance of solid electrolytes. However, current ionic liquid materials offer limited improvement to the performance of solid electrolytes and require further refinement.

[0022] In a first aspect, embodiments of this application provide a composition comprising a ceramic electrolyte and an ionic liquid, wherein the ionic liquid comprises a piperidine-based ionic liquid.

[0023] It should be noted that the piperidine-based ionic liquid is an ionic liquid containing a piperidine group, which includes, but is not limited to, the piperidine group. One or more of them.

[0024] The composition provided in this application uses a piperidine-based ionic liquid to modify a ceramic electrolyte. The piperidine-based ionic liquid has a low viscosity at room temperature, which can provide a stable ion transport medium, enhance ion transport, and improve the ionic conductivity of the ceramic electrolyte. When the composition is applied to the battery 100, it can improve the cycle stability of the battery 100, promote the formation of the solid electrolyte interphase (SEI) layer, inhibit lithium dendrite growth, and improve the performance of the battery 100.

[0025] In some embodiments, the piperidine ionic liquid includes an alkenyl-functionalized piperidine ionic liquid. Existing piperidine ionic liquids for electrolytes are typically piperidine ionic liquids without unsaturated bonds, while the piperidine ionic liquid provided in this application has undergone alkenyl functionalization and contains C=C unsaturated bonds. This results in a lower viscosity of the ionic liquid at room temperature, and the strong electron-withdrawing ability of the unsaturated C=C double bonds can effectively reduce the interaction between cations and solvent molecules, allowing anions to be preferentially reduced and decomposed, which helps to form a good SEI layer, thereby improving the cycle stability of the battery 100.

[0026] Furthermore, the alkenyl-functionalized piperidine ionic liquid includes N-allyl-N-methylpiperidine ionic liquid.

[0027] Furthermore, the N-allyl-N-methylpiperidine ionic liquid includes one or more of N-allyl-N-methylpiperidine hexafluorophosphate (CAS: 2248256-64-4) and N-allyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imine (CAS: 1059624-26-8). Both the hexafluorophosphate in the N-allyl-N-methylpiperidine hexafluorophosphate and the bis(trifluoromethanesulfonyl)imine in the N-allyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imine can promote the formation of a solid electrolyte interface layer, such as a LiF solid electrolyte interface layer, thereby inhibiting lithium dendrite growth and improving the performance of battery 100.

[0028] In some embodiments, the ceramic electrolyte comprises an oxide solid electrolyte.

[0029] In some embodiments, the oxide solid electrolyte includes one or more of perovskite-type materials, NASICON-type materials, and garnet-type materials.

[0030] The perovskite-type material includes Li a La b Ti c A d O e Wherein, 0 < a ≤ 0.5, 0 < b < 0.6, 0.9 < c ≤ 1, 0 ≤ d ≤ 0.25, 2 < e ≤ 3, and A includes one or more of Ba, Sr, and Al. For example, the perovskite material may include Li. 0.5 La 0.5 TiO3, Li 0.29 La 0.57 TiO3, Li 0.30 La 0.57 TiO3, Li 0.33 La 0.56 TiO3, Li 0.34 La0.51 TiO 2.94 Li 0.30 La 0.567 TiO3, Li 0.36 Sr 0.04 La 0.523 TiO3, Li 0.33 Ba 0.25 La 0.39 TiO3 and (Li 0.33 La 0.56 ) 1.005 Ti 0.99 Al 0.01 One or more of O3.

[0031] The NASICON-type material (Na+superionic) includes Li f B g P h O 12 Wherein, 1≤f≤3, 0<g≤4, 1≤h≤3, and B includes one or more of Al, Zr, Ti, Ge, and Si. For example, the NASICON-type material may include LiZr2(PO4)3, LiTi2(PO4)3, LiGe2(PO4)3, and Li... 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP), Li 1.5 Al 0.5 Ge 1.5 (PO4)3(LAGP), Li3Zr2Si2PO 12 Li 1.4 Al 0.4 Ti 1.6 (PO4)3, Li 1.4 Ti2Si 0.4 P 2.6 O 12 -AIPO4 and Li 1.5 Al 0.5 Ti 1.5 One or more of (PO4)3.

[0032] The garnet-type material includes Li i La j Zr k M l O 12 Wherein, 5≤i≤7, 2≤j≤3, 1≤k≤2, 0≤l≤1, and M is selected from any one of Ta, Nb, Hf, Al, Si, Ga, Sc, Ti, V, Y, and Sn. For example, the garnet-type material may include Li7La3Zr2O. 12Li 6.5 La3Zr 1.5 Nb 0.5 O 12 Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Li 6.375 La3Zr 1.375 Nb 0.625 O 12 Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 Li 5.9 Al 0.2 La3Zr 1.75 W 0.25 O 12 、Li7La 2.75 Ca 0.25 Zr 1.75 Nb 0.25 O 12 and Li 6.4 La3Zr 1.4 Ta 0.6 O 12 One or more of them.

[0033] In some embodiments, the ceramic electrolyte comprises ceramic electrolyte particles with an average particle size of 1 μm to 5 μm, such as 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, etc. Within the range of average particle size, the ceramic electrolyte particles have the characteristics of small particle size, good toughness, and large specific surface area, which is beneficial for the contact of ionic liquids with them and improves their ionic conductivity.

[0034] In some embodiments, the mass ratio of the ceramic electrolyte to the ionic liquid is (2.7–10):(0.01–0.1), for example, it can be 3:0.05, 4:0.05, 5:0.05, 6:0.05, 7:0.05, 0.82:0.05, 8:0.05, 9:0.05, 10:0.05, 5:0.02, 5:0.03, 5:0.04, 5:0.06, 5:0.07, 5:0.08, 5:0.09, etc. Within the range of the mass ratio, it is beneficial for the ionic liquid to improve the ionic conductivity of the ceramic electrolyte.

[0035] In some embodiments, the composition comprises the ceramic electrolyte and the ionic liquid.

[0036] In some embodiments, the composition further includes a first lithium salt. The first lithium salt can provide lithium ions, thereby improving the conductivity of the composition.

[0037] In some embodiments, the first lithium salt includes one or more of organic lithium salts and inorganic lithium salts.

[0038] Furthermore, the organic lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalateborate (LiDFOB), and lithium bis(oxalateborate)borate (LiBOB).

[0039] The inorganic lithium salt includes one or more of lithium perchlorate (LiClO4) and lithium hexafluorophosphate (LiPF6).

[0040] In some embodiments, the mass ratio of the ceramic electrolyte to the first lithium salt is (2.7–10):(0.01–0.1), for example, it can be 3:0.05, 4:0.05, 5:0.05, 6:0.05, 7:0.05, 0.82:0.05, 8:0.05, 9:0.05, 10:0.05, 5:0.02, 5:0.03, 5:0.04, 5:0.06, 5:0.07, 5:0.08, 5:0.09, etc. Within the range of the mass ratio, the first lithium salt is beneficial for enhancing ion transport, further improving the ionic conductivity of the composition, and constructing a stable interface layer.

[0041] In some embodiments, the composition further includes an adhesive.

[0042] In some embodiments, the adhesive includes one or more of polyethylene oxide (PEO), polyurethane rubber (TPU), polyvinylidene fluoride (PVDF), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), polyaryleneacetylene (PAA), polycaprolactone (PCL), and polyvinyl butyral (PVB).

[0043] In some embodiments, the mass ratio of the ceramic electrolyte to the binder is (2.7–10):(0.5–0.6), for example, it can be 3:0.55, 4:0.55, 5:0.55, 6:0.55, 7:0.55, 0.82:0.55, 8:0.55, 9:0.55, 10:0.55, 5:0.52, 5:0.53, 5:0.54, 5:0.56, 5:0.57, 5:0.58, 5:0.59, etc. Within the range of the mass ratio, the binder has good thermoplasticity, which is beneficial for forming the materials in the composition into a whole and strengthening the tight bond between the materials.

[0044] In some embodiments, the composition comprises the ceramic electrolyte, the ionic liquid, the first lithium salt, and the binder.

[0045] It is understood that the composition can be obtained by mixing using a dry process or a wet process.

[0046] Secondly, referring to Figure 1, this application embodiment also provides a composite film 10, including a polymer electrolyte film 12 and a ceramic electrolyte film 11 stacked together, wherein the material of the ceramic electrolyte film 11 includes the above-described composition.

[0047] The composite film 10 provided in this application has a polymer electrolyte film 12 with good flexibility and high interface stability with lithium metal, which can work together with the ceramic electrolyte film 11 to form a stable electrode-electrolyte interface.

[0048] In some embodiments, the ceramic electrolyte film 11 is made of the above-described composition.

[0049] In some embodiments, the thickness of the ceramic electrolyte film 11 is 20 μm to 40 μm, for example, it can be 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 31 μm, 33 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, etc.

[0050] Please refer to Figure 2. This application embodiment also provides a method for preparing the above-mentioned ceramic electrolyte film 11, including the following steps:

[0051] S11. The composition is provided, the composition comprising a ceramic electrolyte and an ionic liquid, wherein the ionic liquid comprises a piperidine-based ionic liquid;

[0052] S12. Deposit the composition to obtain a ceramic electrolyte film 11.

[0053] The ceramic electrolyte film 11 can be prepared using a dry process or a wet process. Preferably, the ceramic electrolyte film 11 is prepared using a wet process, which results in a more uniform and flat ceramic electrolyte film 11 with a suitable thickness, thus obtaining a ceramic electrolyte film 11 with better uniformity, ductility, and mechanical properties.

[0054] Specifically, the wet process includes:

[0055] S111. A first solvent is provided and mixed with the composition to obtain a first mixture;

[0056] S112. Deposit the first mixture to obtain a ceramic electrolyte film 11.

[0057] In some embodiments, the mass ratio of the ceramic electrolyte to the first solvent is (2.7–10):(5–20), for example, 3:10, 4:10, 5:10, 6:10, 7:10, 0.82:10, 8:10, 9:10, 10:10, 5:8, 5:10, 5:12, 5:15, 5:18, etc. Within the range of the mass ratio, the first solvent can sufficiently disperse and dissolve the composition.

[0058] In some embodiments, the first solvent includes one or more of N,N-dimethylformamide (DMF), acetonitrile, N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, ethyl acetate, pyrrole, butyric acid, and cresol.

[0059] In some embodiments, mixing the first solvent and the composition includes: mixing the first solvent and the ceramic electrolyte, and then adding the ionic liquid to obtain a first mixture. It is understood that dispersing the ceramic electrolyte in the first solvent before adding the ionic liquid is beneficial for the uniform dispersion of the ceramic electrolyte.

[0060] Further, after mixing the first solvent and the ceramic electrolyte, a first stirring is performed. The stirring speed is 600 r / min to 800 r / min, for example, 620 r / min, 650 r / min, 680 r / min, 700 r / min, 720 r / min, 750 r / min, 780 r / min, etc.; the stirring time is 5 min to 20 min, for example, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc. This facilitates the full dispersion of the ceramic electrolyte and prevents its aggregation and deposition.

[0061] After adding the ionic liquid and mixing, a second stirring is performed. The stirring speed of the second stirring is 800 r / min to 1000 r / min, for example, 820 r / min, 850 r / min, 880 r / min, 900 r / min, 920 r / min, 950 r / min, 980 r / min, etc.; the stirring time is 5 min to 20 min, for example, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc. This facilitates sufficient and uniform contact between the ionic liquid and the ceramic electrolyte, improving the ionic conductivity of the ceramic electrolyte.

[0062] In some embodiments, after obtaining the first mixture and before depositing the first mixture, the process further includes: degassing.

[0063] Furthermore, the degassing is performed at room temperature. The degassing time is 5 min to 20 min, for example, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc. The degassing includes centrifugal degassing, and the centrifugal degassing speed is 1300 r / min to 1500 r / min, for example, 1320 r / min, 1350 r / min, 1380 r / min, 1400 r / min, 1420 r / min, 1450 r / min, 1480 r / min, etc.

[0064] Thus, under the aforementioned degassing conditions, it is beneficial to remove gas from the first mixture and promote the uniformity and stability of the ceramic electrolyte.

[0065] In some embodiments, the composition further includes a first lithium salt. Mixing the first solvent and the composition includes: mixing the first solvent with the ceramic electrolyte and the first lithium salt, and then adding the ionic liquid to obtain a first mixture.

[0066] In some embodiments, the composition further includes a binder. After obtaining the first mixture and before degassing, the process further includes adding the binder and performing a third stirring. The third stirring speed is 600 r / min to 800 r / min, for example, 620 r / min, 650 r / min, 680 r / min, 700 r / min, 720 r / min, 750 r / min, 780 r / min, etc.; the stirring time is 5 min to 20 min, for example, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc. Thus, the binder facilitates sufficient contact and bonding of the ceramic electrolyte, ionic liquid, and first lithium salt into a single unit.

[0067] In some embodiments, after depositing the composition, drying is further included. Further, the drying temperature is 60°C to 100°C, for example, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, etc.; the drying time is 10h to 14h, for example, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, etc. Thus, under the drying conditions, it is beneficial to remove the first solvent and form a uniform and dense ceramic electrolyte film 11.

[0068] In some embodiments, the polymer electrolyte film 12 is made of a polymer electrolyte. Further, the polymer electrolyte comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trifluoroethylene, polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, polyurethane acrylate, polyethylene glycol, and polyvinyl alcohol. The polymer electrolyte can isolate and dissociate lithium salts and conduct lithium ions.

[0069] In some embodiments, the polymer electrolyte film 12 may further include a second lithium salt.

[0070] In some embodiments, the second lithium salt includes one or more of organic lithium salts and inorganic lithium salts.

[0071] Furthermore, the organic lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalateborate (LiDFOB), and lithium bis(oxalateborate)borate (LiBOB).

[0072] The inorganic lithium salt includes one or more of lithium perchlorate (LiClO4) and lithium hexafluorophosphate (LiPF6).

[0073] The second lithium salt may be made of the same or different material as the first lithium salt.

[0074] In some embodiments, the mass ratio of the polymer electrolyte to the second lithium salt is (0.5–2):(0.1–1.5), for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 0.8:1, 1.2:1, 1.5:1, 1.8:1, etc. Within the range of the mass ratio, the second lithium salt is beneficial for enhancing ion transport, further improving the ionic conductivity of the polymer electrolyte film 12.

[0075] In some embodiments, the polymer electrolyte film 12 is composed of the polymer electrolyte and the second lithium salt.

[0076] In some embodiments, the thickness of the polymer electrolyte film 12 is 10 μm to 15 μm, for example, it can be 11 μm, 12 μm, 13 μm, 14 μm, etc.

[0077] Within the thickness range of the ceramic electrolyte film 11 and the polymer electrolyte film 12, it is beneficial to the interfacial contact between the ceramic electrolyte and the polymer electrolyte film 12. The ceramic electrolyte film 11 has excellent ionic conductivity, stability and mechanical properties, and the polymer electrolyte film 12 can promote close contact with the electrode. The two work together to give the composite film 10 good conductivity and stability.

[0078] In some embodiments, the polymer electrolyte film 12 is prepared by a wet molding process, including:

[0079] A polymer electrolyte and a second solvent are provided and mixed to obtain a second mixture;

[0080] The second mixture is deposited to obtain a polymer electrolyte film 12.

[0081] The polymer electrolyte film 12 prepared by the wet method has good uniformity and suitable thickness.

[0082] In some embodiments, the mass ratio of the polymer electrolyte to the second solvent in the mixture is (0.5–2):(5–20), for example, it can be 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 0.8:10, 1:10, 1.2:10, 1.5:10, 1.8:10, etc. Within the range of these mass ratios, it is beneficial for the polymer electrolyte to be uniformly dispersed, thereby improving the film-forming properties of the polymer electrolyte film 12.

[0083] In some embodiments, the second solvent includes one or more of N,N-dimethylformamide (DMF), acetonitrile, N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, ethyl acetate, pyrrole, butyric acid, and cresol.

[0084] It is understood that the deposition of the mixture can be performed using conventional methods in the art, such as blade coating or spin coating. After the mixture is deposited, the process further includes drying to remove the second solvent, thereby obtaining the polymer electrolyte film 12. The drying conditions are the same as those for the drying of ceramic electrolytes described above, and will not be repeated here.

[0085] After preparing the ceramic electrolyte film 11 and the polymer electrolyte film 12 respectively, the two electrolyte films are aligned and stacked to obtain the composite film 10.

[0086] Thirdly, embodiments of this application also provide an application of the above composition, the application including an electrochemical device, the material of which includes the above composition.

[0087] The electrochemical device can be consumer electronics, new energy vehicles, power tools, energy storage devices, etc. For example, the consumer electronics include remote controls, flashlights, alarm clocks, digital cameras, portable audio-visual devices, mobile phones, tablets, laptops, etc.; the power tools include electric vehicles, robots, etc.; and the energy storage devices include photovoltaic-energy storage power stations, wind-energy storage power stations, AGC frequency regulation power stations, substation energy storage, virtual power plants, etc.

[0088] In some embodiments, referring to FIG3, the electrochemical device includes a battery 100, the battery 100 including a positive electrode 20, a negative electrode 30 and the aforementioned ceramic electrolyte film 11, the ceramic electrolyte film 11 being located between the positive electrode 20 and the negative electrode 30.

[0089] In some embodiments, the battery 100 includes a composite film 10, which includes a ceramic electrolyte film 11 and a polymer electrolyte film 12. The composite film 10 is located between the positive electrode 20 and the negative electrode 30, and the ceramic electrolyte film 11 is located between the positive electrode 20 and the polymer electrolyte film 12.

[0090] This application employs a structure in which a ceramic electrolyte film 11 is disposed near the positive electrode 20 and a polymer electrolyte film 12 is disposed near the negative electrode 30. The ceramic electrolyte film 11 utilizes an ionic liquid-modified ceramic electrolyte improved in this application, exhibiting excellent ionic conductivity and stability, which can improve the conductivity of the battery 100. The polymer electrolyte film 12 has good uniformity and flexible mechanical properties. Covering the negative electrode 30 with it is beneficial to improve the affinity with the lithium negative electrode and can serve as a uniform and stable interface layer to promote lithium transport. The synergistic effect of the ceramic electrolyte film 11 and the polymer electrolyte film 12 can promote the stable cycling of the battery 100 system, improve the charge-discharge cycle performance of the battery 100, extend the cycle life of the battery 100, and maintain a high capacity.

[0091] In some embodiments, the material of the positive electrode 20 includes one or more of lithium nickel manganese oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, and lithium nickel cobalt manganese oxide.

[0092] In some embodiments, the negative electrode 30 includes one or more of the following: lithium metal negative electrode, lithium metal alloy negative electrode, graphite negative electrode, silicon-based negative electrode, silicon-graphite composite negative electrode, and copper foil lithium-free negative electrode.

[0093] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0094] Example 1

[0095] This embodiment provides a composition and the ceramic electrolyte thin film prepared therefrom, and the preparation method is as follows:

[0096] Add 5.4g of ceramic electrolyte LLZO and 0.06g of first lithium salt LiClO4 to 7g of the first solvent DMF, and stir at high speed for 10min to completely disperse LLZO.

[0097] Add 0.06 g of the ionic liquid N-allyl-N-methylpiperidine hexafluorophosphate, and stir at high speed for 10 min to ensure complete dispersion;

[0098] Add 0.48g of PVDF binder, stir at high speed for 10 minutes with a mixer, and degas at room temperature using a degassing machine to obtain a first mixture; the first mixture comprises the composition;

[0099] The first mixture was coated onto a PET release film using a 250μm doctor blade and dried at 80℃ to obtain a ceramic electrolyte film with a thickness of 30μm.

[0100] Example 2

[0101] This embodiment is basically the same as Embodiment 1, except that the ceramic electrolyte LLZO is replaced with LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3).

[0102] Example 3

[0103] This embodiment is basically the same as Embodiment 1, except that the ionic liquid N-allyl-N-methylpiperidine hexafluorophosphate is replaced with N-allyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt.

[0104] Example 4

[0105] This embodiment is basically the same as Embodiment 1, except that the first lithium salt LiClO4 is replaced with LiFSI in this embodiment.

[0106] Example 5

[0107] This embodiment is basically the same as Embodiment 1, except that the adhesive PVDF is replaced with PEO in this embodiment.

[0108] Example 6

[0109] This embodiment is basically the same as Embodiment 1, except that the mass of the ionic liquid N-allyl-N-methylpiperidine hexafluorophosphate in this embodiment is 0.1g.

[0110] Example 7

[0111] This embodiment is basically the same as Embodiment 1, except that the mass of the ionic liquid N-allyl-N-methylpiperidine hexafluorophosphate in this embodiment is 0.01g.

[0112] Example 8

[0113] This embodiment is basically the same as Embodiment 1, except that the mass of the first lithium salt, lithium bis(trifluoromethanesulfonyl)imide, is 0.1g in this embodiment.

[0114] Example 9

[0115] This embodiment is basically the same as Embodiment 1, except that the mass of the first lithium salt, lithium bis(trifluoromethanesulfonyl)imide, is 0.01g in this embodiment.

[0116] Example 10

[0117] This embodiment is basically the same as Embodiment 1, except that the mass of the PVDF adhesive in this embodiment is 0.6g.

[0118] Example 11

[0119] This embodiment is basically the same as Embodiment 1, except that the mass of the PVDF adhesive in this embodiment is 0.05g.

[0120] Example 12

[0121] This embodiment is basically the same as Embodiment 1, except that the thickness of the ceramic electrolyte film in this embodiment is 40 μm.

[0122] Example 13

[0123] This embodiment is basically the same as Embodiment 1, except that the thickness of the ceramic electrolyte film in this embodiment is 20 μm.

[0124] Comparative Example 1

[0125] This comparative example is basically the same as Example 1, except that the composition in this comparative example does not contain the ionic liquid N-allyl-N-methylpiperidine hexafluorophosphate.

[0126] Comparative Example 2

[0127] This comparative example is basically the same as Example 1, except that the ionic liquid N-allyl-N-methylpiperidine hexafluorophosphate is replaced with 1-ethoxyethyl-3-methylimidazolium tetrafluoroborate.

[0128] Comparative Example 3

[0129] This comparative example is basically the same as Example 1, except that the ionic liquid N-allyl-N-methylpiperidine hexafluorophosphate is replaced with N-propyl-N-methylpiperidine hexafluorophosphate in this comparative example.

[0130] The ionic conductivity of the compositions of Examples 1-13 and Comparative Examples 1-3 was tested respectively, and the results are shown in Table 1.

[0131] Ionic conductivity was measured by cutting the thin film into 16mm diameter discs, assembling symmetrical cells by sandwiching the discs between two stainless steel spacers, connecting them to an electrochemical workstation, and performing impedance testing to obtain the bulk impedance value of the sample.

[0132] The ionic conductivity is calculated using the formula σ = l / (AR), with units of S / cm; l is the thickness of the composite electrolyte membrane, with units of cm; and A is the area of ​​the composite electrolyte membrane, with units of cm². 2R is the volume impedance of the sample to be tested, in Ω.

[0133] Table 1

[0134] As shown in Table 1:

[0135] As can be seen from Examples 1-5 and Comparative Examples 1-3, the piperidine-based ionic liquids provided in this application have wide adaptability to ceramic electrolytes. Modifying ceramic electrolytes with the piperidine-based ionic liquids provided in this application can provide a stable ion transport medium, enhance ion transport, and improve the ionic conductivity of ceramic electrolytes. In Comparative Example 1, no ionic liquid was used, and the ionic conductivity of the ceramic electrolyte was relatively poor. In Comparative Example 2, the performance improvement of the ceramic electrolyte by the conventional ionic liquid was worse than that of Comparative Example 3. Comparative Example 3 used a piperidine-based ionic liquid without unsaturated bonds, which had a certain improvement effect on the ionic conductivity of the ceramic electrolyte, but it was worse than the piperidine-based ionic liquid containing unsaturated bonds used in the examples.

[0136] As can be seen from Examples 1, 6-11 and Comparative Example 1, the mass ratio of each component (ceramic electrolyte, ionic liquid, lithium salt, binder) in the composition has a certain influence on the ionic conductivity of the composition. Compared with Comparative Example 1, the ionic conductivity of the composition is significantly improved within the range of the mass ratio of each component provided in this application.

[0137] As can be seen from Examples 1, 12-13 and Comparative Example 1, the thickness of the ceramic electrolyte film has a significant effect on the ionic conductivity. Compared with Comparative Example 1, the ionic conductivity of Examples 1 and 12-13 is much higher than that of Comparative Example 1, indicating that the piperidine ionic liquid provided in this application can significantly improve the conductivity of the composition and increase the ionic conductivity of the composition.

[0138] Application Example 1

[0139] This application example provides a composite thin film and a battery, the preparation method of which is as follows:

[0140] 0.5g of the second lithium salt LiFSI and 1.0g of the polymer electrolyte PVDF were dissolved in 10g of the second solvent DMF and stirred at room temperature for 12h to prepare a second mixture. The mixture was then coated on a glass plate using a solution casting-drying method with a 250μm doctor blade and dried at 80℃ to obtain a polymer electrolyte film with a thickness of 10μm.

[0141] The ceramic electrolyte film of Example 1 and the polymer electrolyte film described above are aligned and stacked to obtain a composite film;

[0142] Under the inert atmosphere of a glove box, the positive electrode, composite film, and negative electrode were assembled sequentially. The ceramic electrolyte film of the composite film was placed near the positive electrode, and the polymer electrolyte film was placed near the negative electrode. The assembly was completed by pressing at 800 kPa for 5 seconds to obtain the Li||NMC811 battery.

[0143] Application Examples 2-13

[0144] Application Examples 2-13 are basically the same as Application Example 1, except that the ceramic electrolyte film of Example 1 is replaced with the ceramic electrolyte film of Example 2-13 in Application Examples 2-13.

[0145] Application Example 14

[0146] Application Example 14 is basically the same as Application Example 1, except that Application Example 14 does not contain a polymer electrolyte film, but directly places the ceramic electrolyte film between the positive and negative electrodes.

[0147] Application Comparative Examples 1-3

[0148] Application Comparative Examples 1 to 3 are basically the same as Application Example 1, except that the ceramic electrolyte film of Example 1 is replaced with the ceramic electrolyte film of Comparative Examples 1 to 3 in Application Comparative Examples 1 to 3.

[0149] Application Comparative Example 4

[0150] Comparative Example 4 is basically the same as Comparative Example 1, except that Comparative Example 4 does not contain a ceramic electrolyte film, but directly places the polymer electrolyte film between the positive and negative electrodes.

[0151] The ionic conductivity of the composite films used in Examples 1-14 and Comparative Examples 1-4, as well as the cycle life and capacity retention of the batteries, were tested respectively. The data results are shown in Table 2.

[0152] The test method for cycle life and capacity retention (cycle curve) is as follows: the battery is charged to 4.2V at 0.33C constant current and constant voltage at 25℃, and then discharged to 3.0V at 0.5C constant current. This constitutes one cycle. The remaining capacity is the capacity retention rate. The cycle number or capacity retention rate of each battery is compared.

[0153] Table 2

[0154] As shown in Table 2:

[0155] As can be seen from Application Examples 1-5 and Comparative Examples 1-3, the composite film provided in this application has a significantly improved ionic conductivity and a significantly improved battery life compared to the composite films of Comparative Examples 1-3. After more than 95 cycles, it can still maintain 80% of its capacity. The effect of Comparative Example 1 is worse than that of Comparative Example 2, and the effect of Comparative Example 2 is worse than that of Comparative Example 3. This shows that piperidine ionic liquids have a better effect on improving ceramic electrolytes than conventional ionic liquids, and piperidine ionic liquids containing unsaturated bonds have a better effect, which is beneficial to improving the cycle performance of the battery.

[0156] As can be seen from Application Examples 1, 6-11 and Application Comparative Example 1, within the range of the mass ratios of each component provided in this application, the ionic conductivity of the composition is significantly improved, thereby increasing the ionic conductivity of the composite film and extending the cycle life and capacity retention of the battery; the batteries in Application Examples 6-11 still have excellent capacity retention after more than 100 cycles, indicating that their stability is also improved.

[0157] As can be seen from Application Examples 1, 12-14 and Comparative Examples 1, 4, within the thickness range of the ceramic electrolyte film provided in this application, the composite films of Application Examples 1, 12-13 all have high ionic conductivity, and the batteries all have long cycle life and capacity retention. The battery in Application Example 14 contains only a ceramic electrolyte film, and its cycle life is significantly higher than that of the battery in Comparative Example 4 which contains only a polymer electrolyte film, but lower than that of the application examples. This indicates that the ceramic electrolyte film and the polymer electrolyte film can work synergistically. As a composite film, it not only improves the conductivity of the battery, but also promotes the affinity with the electrode, thereby improving the overall stable cycling of the battery system.

[0158] The compositions, composite films, and applications provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composition, characterized in that, It includes ceramic electrolytes and ionic liquids, wherein the ionic liquids include piperidine-based ionic liquids.

2. The composition according to claim 1, characterized in that, The mass ratio of the ceramic electrolyte to the ionic liquid is (2.7–10):(0.01–0.1); and / or The piperidine ionic liquids include alkenyl-functionalized piperidine ionic liquids; and / or The ceramic electrolyte includes an oxide solid electrolyte; the oxide solid electrolyte includes one or more of perovskite type materials, NASICON type materials, and garnet type materials.

3. The composition according to claim 2, characterized in that, The alkenyl-functionalized piperidine ionic liquid includes N-allyl-N-methylpiperidine ionic liquids; the N-allyl-N-methylpiperidine ionic liquid includes one or more of N-allyl-N-methylpiperidine hexafluorophosphate and N-allyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt; and / or The perovskite-type material includes Li a La b Ti c A d O e Where 0 < a ≤ 0.5, 0 < b < 0.6, 0.9 < c ≤ 1, 0 ≤ d ≤ 0.25, 2 < e ≤ 3, and A includes one or more of Ba, Sr, and Al; and / or The NASICON-type material includes Li f B g P h O 12 Wherein, 1≤f≤3, 0<g≤4, 1≤h≤3, and B includes one or more of Al, Zr, Ti, Ge, and Si; and / or The garnet-type material includes Li i La j Zr k M l O 12 Where 5≤i≤7, 2≤j≤3, 1≤k≤2, 0≤l≤1, and M is selected from any one of Ta, Nb, Hf, Al, Si, Ga, Sc, Ti, V, Y, and Sn; and / or The ceramic electrolyte comprises ceramic electrolyte particles, the average particle size of which is 1 μm to 5 μm.

4. The composition according to claim 3, characterized in that, The perovskite-type material includes Li 0.5 La 0.5 TiO3, Li 0.29 La 0.57 TiO3, Li 0.30 La 0.57 TiO3, Li 0.33 La 0.56 TiO3, Li 0.34 La 0.51 TiO 2.94 Li 0.30 La 0.567 TiO3, Li 0.36 Sr 0.04 La 0.523 TiO3, Li 0.33 Ba 0.25 La 0.39 TiO3 and (Li 0.33 La 0.56 ) 1.005 Ti 0.99 Al 0.01 One or more of O3; and / or The NASICON-type materials include LiZr2(PO4)3, LiTi2(PO4)3, LiGe2(PO4)3, and Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, Li3Zr2Si2PO 12 Li 1.4 Al 0.4 Ti 1.6 (PO4)3, Li 1.4 Ti2Si 0.4 P 2.6 O 12 -AIPO4 and Li 1.5 Al 0.5 Ti 1.5 One or more of (PO4)3; and / or The garnet-type material includes Li7La3Zr2O 12 Li 6.5 La3Zr 1.5 Nb 0.5 O 12 , Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Li 6.375 La3Zr 1.375 Nb 0.625 O 12 Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 Li 5.9 Al 0.2 La3Zr 1.75 W 0.25 O 12 、Li7La 2.75 Ca 0.25 Zr 1.75 Nb 0.25 O 12 and Li 6.4 La3Zr 1.4 Ta 0.6 O 12 One or more of them.

5. The composition according to claim 1, characterized in that, The composition further includes one or more of a first lithium salt and a binder.

6. The composition according to claim 5, characterized in that, The first lithium salt comprises one or more of organic lithium salts and inorganic lithium salts; optionally, the organic lithium salt comprises one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalate borate, and lithium bis(oxalate borate); optionally, the inorganic lithium salt comprises one or more of lithium perchlorate and lithium hexafluorophosphate; and / or The adhesive includes one or more of polyethylene oxide, polyurethane rubber, polyvinylidene fluoride, polyvinylidene fluoride hexafluoropropylene, polyarylene, polycaprolactone, and polyvinyl butyral.

7. The composition according to claim 5, characterized in that, The mass ratio of the ceramic electrolyte to the first lithium salt is (2.7–10):(0.01–0.1); and / or The mass ratio of the ceramic electrolyte to the binder is (2.7-10):(0.5-0.6).

8. A composite film, characterized in that, It includes a polymer electrolyte film and a ceramic electrolyte film stacked together, wherein the material of the ceramic electrolyte film includes the composition as described in any one of claims 1 to 7.

9. The composite film as described in claim 8, characterized in that, The ceramic electrolyte thin film is prepared by the following steps: The composition is provided, the composition comprising a ceramic electrolyte and an ionic liquid, wherein the ionic liquid comprises a piperidine-based ionic liquid; The composition is deposited to obtain a ceramic electrolyte film.

10. The composite film as described in claim 9, characterized in that, The mass ratio of the ceramic electrolyte to the ionic liquid is (2.7–10):(0.01–0.1); and / or The thickness of the ceramic electrolyte film is 20 μm to 40 μm; and / or The thickness of the polymer electrolyte film is 10 μm to 15 μm.

11. The composite film as described in claim 9, characterized in that, The ceramic electrolyte film is prepared using a wet process; the wet process includes the following steps. A first solvent is provided and mixed with the composition to obtain a first mixture; The first mixture is deposited to obtain a ceramic electrolyte film.

12. The composite film as described in claim 11, characterized in that, The first solvent comprises one or more of N,N-dimethylformamide, acetonitrile, N-methyl-2-pyrrolidone, dimethylacetamide, chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, ethyl acetate, pyrrole, butyric acid, and cresol; and / or The mass ratio of the ceramic electrolyte to the first solvent is (2.7–10):(5–20); and / or The mixing of the first solvent and the composition includes: mixing the first solvent and the ceramic electrolyte, and then adding the ionic liquid to mix, to obtain a first mixture.

13. The composite film as described in claim 12, characterized in that, After the first solvent and the ceramic electrolyte are mixed, a first stirring is performed; and / or The process of adding the ionic liquid and mixing includes performing a second stirring; and / or After obtaining the first mixture and before depositing the first mixture, the method further includes: degassing; and / or After depositing the composition, drying is also included.

14. The composite film as described in claim 13, characterized in that, The first stirring speed is 600 r / min to 800 r / min, and the time is 5 min to 20 min; and / or The second stirring speed is 800 r / min to 1000 r / min, and the time is 5 min to 20 min; and / or The degassing is performed at room temperature; and / or The degassing time is 5 min to 20 min; and / or The degassing includes centrifugal degassing at a speed of 1300 r / min to 1500 r / min; and / or The drying temperature is 60℃~100℃, and the time is 10h~14h.

15. The composite film as described in claim 13, characterized in that, The composition further includes a first lithium salt; mixing the first solvent and the composition comprises: mixing the first solvent with the ceramic electrolyte and the first lithium salt, and then adding the ionic liquid and mixing. A first mixture is obtained; and / or The composition further includes a binder; after obtaining the first mixture and before degassing, the composition further includes: adding the binder and performing a third stirring; optionally, the third stirring speed is 600 r / min to 800 r / min and the time is 5 min to 20 min.

16. The composite film as described in claim 8, characterized in that, The polymer electrolyte film is made of a polymer electrolyte and a second lithium salt.

17. The composite film as described in claim 16, characterized in that, The polymer electrolyte comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trifluoroethylene, polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, polyurethane acrylate, polyethylene glycol, and polyvinyl alcohol; and / or The second lithium salt includes one or more of organic lithium salts and inorganic lithium salts; the organic lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalateborate, and lithium bis(oxalateborate); the inorganic lithium salt includes one or more of lithium perchlorate and lithium hexafluorophosphate; and / or The mass ratio of the polymer electrolyte to the second lithium salt is (0.5-2):(0.1-1.5).

18. An electrochemical device, characterized in that, The materials of the electrochemical device include the compositions as described in any one of claims 1 to 7.

19. The electrochemical device as claimed in claim 18, characterized in that, The electrochemical device includes a battery, which includes a positive electrode, a negative electrode, and a ceramic electrolyte film, wherein the material of the ceramic electrolyte film includes the composition.

20. The electrochemical device as claimed in claim 19, characterized in that, The battery includes a composite film, which comprises a ceramic electrolyte film and a polymer electrolyte film. The composite film is located between the positive electrode and the negative electrode, and the ceramic electrolyte film is located between the positive electrode and the polymer electrolyte film.

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