Preparation method and application of solid electrolyte membrane based on ionic liquid modification
A solid electrolyte membrane with high ionic conductivity, high cycle stability and excellent mechanical properties was prepared by modifying polymers with ionic liquids in a specific ratio. This method solves the performance deficiencies of traditional solid electrolytes and is suitable for lithium-ion battery applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-22
- Publication Date
- 2026-03-24
AI Technical Summary
Traditional solid electrolytes suffer from low ionic conductivity, poor long-term cycling stability, and unsatisfactory mechanical properties. In particular, after the introduction of ionic liquid modification, the migration of lithium ions is hindered, leading to a decrease in performance.
An electrolyte dispersion was prepared by mixing an ionic liquid with a polymer and lithium salt in a specific ratio. The dispersion was then dried to form a solid electrolyte membrane with a thickness of 15 μm to 150 μm and a density of 0.2 g/cm3 to 0.5 g/cm3. Polyvinylidene fluoride was modified with an ionic liquid containing imidazole bis(trifluoromethanesulfonyl)imide to transform its γ phase into a strongly polar β phase, thereby improving its ionic conductivity and mechanical properties.
It significantly improves the ionic conductivity and long-term cycling stability of solid electrolyte membranes while maintaining excellent mechanical properties, making it suitable for battery applications with high energy density and a wide electrochemical stability window.
Smart Images
Figure CN121726518A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery materials technology, and in particular to a method for preparing and applying a solid electrolyte membrane based on ionic liquid modification. Background Technology
[0002] Traditional lithium-ion batteries use flammable and volatile organic liquid electrolytes, posing safety hazards such as leakage, combustion, and explosion. Especially under extreme temperature conditions, the flammability of the electrolyte can cause a rapid accumulation of heat inside the battery, leading to serious safety accidents. To address these issues, solid-state electrolytes have emerged as a highly promising solution. By solidifying the electrolyte, solid-state electrolytes effectively avoid safety hazards such as leakage, spontaneous combustion, volatilization, and explosion, while also offering advantages such as high energy density, a wide electrochemical stability window, long cycle life, and a wide operating temperature range. However, common solid-state electrolytes still have some limitations. For example, while inorganic ceramic electrolytes have relatively high ionic conductivity, they suffer from high density and poor interfacial properties; polymer electrolytes, while possessing good flexibility and film-forming properties, exhibit low room-temperature ionic conductivity.
[0003] To improve the performance of solid-state electrolytes, researchers have begun exploring novel electrolyte materials and modification methods. Among these, ionic liquids, due to their non-flammability, lack of ignition point, high thermal stability, and high conductivity, have become an important research direction for solid-state electrolytes.
[0004] Introducing ionic liquids can improve the ionic conductivity of solid electrolytes to some extent. However, the high viscosity of ionic liquids can hinder the migration of lithium ions, and the introduced ions may participate in electrode reactions, leading to reduced performance and poor long-term cycle capacity retention. Furthermore, ionic liquids at polymer interfaces can easily cause a decrease in the mechanical properties of solid electrolyte membranes, which is not conducive to the thinning of solid electrolyte membranes. Due to these and other issues, the performance of traditional ionic liquid-modified solid electrolytes still needs to be improved. Summary of the Invention
[0005] Therefore, it is necessary to provide a method for preparing and applying a solid electrolyte membrane based on ionic liquid modification, so as to obtain a solid electrolyte membrane with high ionic conductivity, high long-term cycling stability and good mechanical properties.
[0006] In a first aspect, this application provides a method for preparing a solid electrolyte membrane based on ionic liquid modification.
[0007] In some embodiments, the method for preparing a solid electrolyte membrane includes the following steps:
[0008] An electrolyte dispersion is prepared by mixing an ionic liquid, a polymer, a lithium salt, and a solvent.
[0009] The electrolyte dispersion is dried to form a film, thereby preparing a solid electrolyte membrane.
[0010] In the electrolyte dispersion, the mass ratio of the ionic liquid to the polymer is 1:(0.8~5), and the mass ratio of the lithium salt to the polymer is 1:(0.5~5);
[0011] The polymer contains vinylidene fluoride segments;
[0012] The ionic liquid includes one or more of 1-butyl-3-methylimidazolium bis(fluoromethylsulfonyl)imide and 1-butyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imide.
[0013] In some embodiments, the polymer includes one or more of polyvinylidene fluoride homopolymer and polyvinylidene fluoride-hexafluoropropylene copolymer;
[0014] And / or, the average molecular weight of the polymer is 400,000 to 600,000.
[0015] In some embodiments of the solid electrolyte membrane, the thickness of the solid electrolyte membrane is 15 μm to 150 μm; and / or
[0016] The density of the solid electrolyte membrane is 0.2 g / cm³. 3 ~0.5g / cm 3 ; and / or
[0017] The solid electrolyte membrane has an ionic conductivity of 0.1 mS / cm to 1.4 mS / cm at 25°C; and / or
[0018] The tensile strength of the solid electrolyte is 0.5 MPa to 3 MPa.
[0019] In some embodiments, the solvent includes one or more of N,N-dimethylformamide, tetrahydrofuran, dimethylacetamide, tetramethylurea, dimethyl sulfoxide, N-methylpyrrolidone, acetone, cyclohexanone, n-butyl acetate, methyl isobutyl ketone, and ethylene glycol diethyl ether.
[0020] In some embodiments, the lithium salt includes one or more of LiPF6, LiClO4, LiAsF6, LiBF4, LiBOB, LiDFOB, LiTFSI, LiFSI, LiPO2F2, and LiTDI.
[0021] In some embodiments, the process of preparing the electrolyte dispersion includes:
[0022] An electrolyte mixture is prepared by mixing ionic liquids, polymers, and lithium salts.
[0023] The electrolyte mixture and solvent were stirred continuously at 25°C to 80°C for 4 to 24 hours.
[0024] In some embodiments, the process of preparing a solid electrolyte membrane includes:
[0025] The electrolyte dispersion was placed in a substrate and dried at 25°C to 120°C for 4 to 24 hours to obtain the solid electrolyte membrane.
[0026] In a second aspect, this application provides a solid electrolyte membrane prepared using the above-described method for preparing a solid electrolyte membrane.
[0027] In a third aspect, this application provides a battery comprising a positive electrode and a negative electrode, and a solid electrolyte membrane obtained by the above-described preparation method or the above-described solid electrolyte membrane.
[0028] In a fourth aspect, this application provides an electrical device including the aforementioned battery.
[0029] Research has shown that by modifying polyvinylidene fluoride (PVDF) with an ionic liquid containing imidazole-based bis(trifluoromethanesulfonyl)imide at a specific ratio, the γ-phase (T3GT3G') of PVDF segments can be effectively transformed into a highly polar β-phase (TTT), thereby significantly improving the piezoelectric, thermoelectric, ferroelectric properties, and ionic conductivity of the PVDF segments. Simultaneously, thanks to the excellent mechanical and film-forming properties of PVDF itself, it can effectively mitigate the negative effects of the ionic liquid, resulting in a solid electrolyte membrane that combines high ionic conductivity, high capacity retention, and excellent mechanical properties. Attached Figure Description
[0030] 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.
[0031] Figure 1 This is a test graph showing the ionic conductivity of the solid electrolyte membrane in Example 1 of this application.
[0032] Figure 2 The images show the XRD patterns of the electrolyte mixtures and the PVDF powder used in Examples 2-5 of this application.
[0033] Figure 3 These are morphological images of the solid electrolyte membranes of Examples 2-5 of this application, where a-d are morphological images of Examples 2-5 respectively. Detailed Implementation
[0034] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0035] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In this application, "at least one" means one or more, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc.
[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0037] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0038] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
[0039] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.
[0040] Unless otherwise specified, the average molecular weight of polymers used in this application refers to weight-average molecular weight.
[0041] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.
[0042] Solid-state electrolytes, by solidifying the electrolyte, effectively avoid safety hazards such as leakage, spontaneous combustion, volatilization, and explosion. They also offer advantages such as high energy density, a wide electrochemical stability window, long cycle life, and a wide operating temperature range. However, common solid-state electrolytes still have some drawbacks. For example, while inorganic ceramic electrolytes have relatively high ionic conductivity, they suffer from high density and poor interfacial properties; polymer electrolytes, while possessing good flexibility and film-forming properties, exhibit low room-temperature ionic conductivity.
[0043] Introducing ionic liquids can effectively improve the ionic conductivity of solid electrolytes. However, the high viscosity of ionic liquids can hinder lithium-ion migration, and the introduced ions may participate in electrode reactions, leading to reduced performance and poor long-term cycle capacity retention. Furthermore, ionic liquids at polymer interfaces can cause a decrease in the mechanical properties of solid electrolyte membranes, which is not conducive to the thinning of solid electrolyte membranes. Due to these and other issues, the performance of traditional ionic liquid-modified solid electrolytes still needs to be improved.
[0044] Based on this, the first aspect of this application provides a method for preparing a solid electrolyte membrane based on ionic liquid modification, so as to obtain a solid electrolyte membrane with high ionic conductivity, high long-term cycling stability and good mechanical properties.
[0045] In some embodiments, the method for preparing a solid electrolyte membrane includes the following steps:
[0046] An electrolyte dispersion is prepared by mixing an ionic liquid, a polymer, a lithium salt, and a solvent.
[0047] The electrolyte dispersion was dried to form a film, thus preparing a solid electrolyte membrane.
[0048] In the electrolyte dispersion, the mass ratio of ionic liquid to polymer is 1:(0.8~5), and the mass ratio of lithium salt to polymer is 1:(0.5~5);
[0049] The polymer contains vinylidene fluoride segments;
[0050] Ionic liquids include one or more of 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide and 1-butyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imide.
[0051] Polyvinylidene fluoride (PVDF) possesses a relatively high dielectric constant, a wide electrochemical stability window, excellent mechanical properties, and film-forming properties, making it commonly used in the preparation of polymeric solid electrolytes. Studies have shown that by modifying PVDF with ionic liquids containing 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide or 1-butyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imide in specific proportions, the γ-phase (T3GT3G') of PVDF can be effectively transformed into a highly polar β-phase (TTT), thereby significantly improving the piezoelectric, thermoelectric, ferroelectric properties, and ionic conductivity of the PVDF membrane. Simultaneously, thanks to the excellent mechanical and film-forming properties of PVDF itself, it can effectively mitigate the negative effects of ionic liquids, resulting in a solid electrolyte membrane that combines high ionic conductivity, high capacity retention, and excellent mechanical properties.
[0052] In some embodiments, the polymer includes one or more of polyvinylidene fluoride homopolymer and polyvinylidene fluoride-hexafluoropropylene copolymer.
[0053] In some embodiments, the average molecular weight of the polymer is 400,000 to 600,000. Optionally, the average molecular weight of the polymer can be, but is not limited to, 400,000, 500,000, 600,000, or other values in the range of 400,000 to 600,000.
[0054] In some embodiments, the thickness of the solid electrolyte membrane is 15 μm to 150 μm. Optionally, the thickness of the solid electrolyte membrane can be, but is not limited to, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 100 μm, 120 μm, 150 μm, or other values within the range of 15 μm to 150 μm.
[0055] In some embodiments, the density of the solid electrolyte membrane is 0.2 g / cm³. 3 ~0.5g / cm 3 .
[0056] In some embodiments, the ionic conductivity of the solid electrolyte membrane at 25°C is 0.1 mS / cm to 1.4 mS / cm. Optionally, the ionic conductivity of the solid electrolyte membrane at 25°C can be, but is not limited to, 0.1 mS / cm, 0.3 mS / cm, 0.5 mS / cm, 0.7 mS / cm, 0.8 mS / cm, 0.9 mS / cm, 1 mS / cm, 1.1 mS / cm, 1.2 mS / cm, 1.3 mS / cm, 1.4 mS / cm, or other values within the range of 0.1 mS / cm to 1.4 mS / cm.
[0057] In some embodiments, the tensile strength of the solid electrolyte is 0.5 MPa to 3 MPa. Optionally, the tensile strength of the solid electrolyte can be, but is not limited to, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, or other values within the range of 0.5 MPa to 3 MPa.
[0058] The tensile strength of a solid electrolyte membrane varies with its thickness. In some embodiments, for a solid electrolyte membrane with a thickness of 20 μm to 80 μm, the tensile strength is 1.5 MPa to 3 MPa.
[0059] In some embodiments, the solvent includes one or more of N,N-dimethylformamide, tetrahydrofuran, dimethylacetamide, tetramethylurea, dimethyl sulfoxide, N-methylpyrrolidone, acetone, cyclohexanone, n-butyl acetate, methyl isobutyl ketone, and ethylene glycol diethyl ether.
[0060] In some embodiments, the lithium salt includes one or more of LiPF6, LiClO4, LiAsF6, LiBF4, LiBOB, LiDFOB, LiTFSI, LiFSI, LiPO2F2, and LiTDI. Further, the lithium salt includes one or more of LiPF6, LiTFSI, and LiFSI.
[0061] In some embodiments, the process of preparing the electrolyte dispersion includes:
[0062] An electrolyte mixture is prepared by mixing ionic liquids, polymers, and lithium salts.
[0063] The electrolyte mixture is mixed with a solvent to prepare an electrolyte dispersion.
[0064] Optionally, the electrolyte mixture and solvent are stirred continuously at 25°C to 80°C for 4 to 24 hours.
[0065] Optionally, during the preparation of the electrolyte dispersion, the mixing temperature can be, but is not limited to, 25°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, or other values within the range of 25°C to 80°C.
[0066] Optionally, during the preparation of the electrolyte dispersion, the stirring time can be, but is not limited to, 4h, 8h, 12h, 16h, 20h, 24h or other values within the range of 4h to 24h.
[0067] In some embodiments, the process of preparing a solid electrolyte membrane includes:
[0068] The electrolyte dispersion was placed in a substrate and dried at 25°C to 120°C for 4 to 24 hours to obtain the solid electrolyte membrane.
[0069] Alternatively, the drying method may include vacuum drying.
[0070] Optionally, during the preparation of the solid electrolyte membrane, the drying temperature can be, but is not limited to, 25°C, 350°C, 40°C, 60°C, 80°C, 100°C, 120°C, or other values within the range of 40°C to 120°C.
[0071] Optionally, during the preparation of the solid electrolyte membrane, the drying time can be, but is not limited to, 4h, 8h, 12h, 16h, 20h, 24h, or other values within the range of 4h to 24h.
[0072] In some of these implementations, the drying method includes vacuum drying.
[0073] In a second aspect, this application provides a solid electrolyte membrane prepared using the above-described method for preparing a solid electrolyte membrane.
[0074] In some embodiments, the thickness of the solid electrolyte membrane is 15 μm to 150 μm.
[0075] In some embodiments, the density of the solid electrolyte membrane is 0.2 g / cm³. 3 ~0.5g / cm 3 .
[0076] In some embodiments, the solid electrolyte membrane has an ionic conductivity of 0.1 mS / cm to 1.4 mS / cm at 25°C.
[0077] In some embodiments, the tensile strength of the solid electrolyte is 0.5 MPa to 3 MPa.
[0078] In a third aspect, this application provides a battery comprising a positive electrode and a negative electrode, and a solid electrolyte membrane obtained by the above-described preparation method or the above-described solid electrolyte membrane.
[0079] In a fourth aspect, this application provides an electrical device including the aforementioned battery. The electrical device may include mobile devices and electric vehicles. The mobile device may be a mobile phone, a laptop computer, etc.; the electric vehicle may be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
[0080] The present application will be further described in detail below with reference to specific embodiments.
[0081] Unless otherwise specified, the raw materials used in the following specific embodiments and comparative examples are all commercially available products; the instruments used are all commercially available products; and the processes used are all conventionally selected by those skilled in the art unless otherwise specified. The average molecular weight of the polyvinylidene fluoride used below is 500,000.
[0082] Example 1
[0083] This embodiment provides a solid electrolyte membrane.
[0084] The method for preparing the solid electrolyte membrane in this embodiment is as follows:
[0085] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 0.2 g of polyvinylidene fluoride, and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0086] Example 2
[0087] This embodiment provides a solid electrolyte membrane.
[0088] The method for preparing the solid electrolyte membrane in this embodiment is as follows:
[0089] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 0.4 g of polyvinylidene fluoride, and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0090] Example 3
[0091] This embodiment provides a solid electrolyte membrane.
[0092] The method for preparing the solid electrolyte membrane in this embodiment is as follows:
[0093] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 0.6 g of polyvinylidene fluoride, and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0094] Example 4
[0095] This embodiment provides a solid electrolyte membrane.
[0096] The method for preparing the solid electrolyte membrane in this embodiment is as follows:
[0097] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 0.8 g of polyvinylidene fluoride, and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0098] Example 5
[0099] This embodiment provides a solid electrolyte membrane.
[0100] The method for preparing the solid electrolyte membrane in this embodiment is as follows:
[0101] 0.2 g of ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.6 g of polyvinylidene fluoride, and 0.2 g of lithium salt LiFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0102] Example 6
[0103] This embodiment provides a solid electrolyte membrane.
[0104] The method for preparing the solid electrolyte membrane in this embodiment is as follows:
[0105] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 0.6 g of polyvinylidene fluoride and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture; the electrolyte mixture was dispersed in 3 mL of tetrahydrofuran and stirred continuously at 30 °C for 12 h to obtain an electrolyte dispersion; the electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h and then dried at 60 °C for 12 h to obtain a solid electrolyte membrane.
[0106] Example 7
[0107] This embodiment provides a solid electrolyte membrane.
[0108] The method for preparing the solid electrolyte membrane in this embodiment is as follows:
[0109] 0.2 g of ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.6 g of polyvinylidene fluoride and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture; the electrolyte mixture was dispersed in 3 mL of tetrahydrofuran and stirred continuously at 30 °C for 12 h to obtain an electrolyte dispersion; the electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h and then dried at 60 °C for 12 h to obtain a solid electrolyte membrane.
[0110] Comparative Example 1
[0111] This comparative example provides a solid electrolyte membrane.
[0112] The preparation method of the solid electrolyte membrane in this comparative example is as follows:
[0113] 0.4 g of ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.1 g of polyvinylidene fluoride-hexafluoropropylene copolymer, and 0.2 g of lithium salt LiFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0114] Comparative Example 2
[0115] This comparative example provides a solid electrolyte membrane.
[0116] The preparation method of the solid electrolyte membrane in this comparative example is as follows:
[0117] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 0.1 g of polyvinylidene fluoride-hexafluoropropylene copolymer, and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0118] Comparative Example 3
[0119] This comparative example provides a solid electrolyte membrane.
[0120] The preparation method of the solid electrolyte membrane in this comparative example is as follows:
[0121] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 1.2 g of polyvinylidene fluoride-hexafluoropropylene copolymer, and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0122] Comparative Example 4
[0123] This comparative example provides a solid electrolyte membrane.
[0124] The preparation method of the solid electrolyte membrane in this comparative example is as follows:
[0125] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide, 0.6 g of polyvinylidene fluoride-hexafluoropropylene copolymer, and 1.6 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0126] Comparative Example 5
[0127] This comparative example provides a solid electrolyte membrane.
[0128] The preparation method of the solid electrolyte membrane in this comparative example is as follows:
[0129] 0.2 g of ionic liquid 1-butyl-1-methylpyrrolidone bis(fluorosulfonyl)imide and 0.6 g of polyvinylidene fluoride were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0130] Comparative Example 6
[0131] This comparative example provides a solid electrolyte membrane.
[0132] The preparation method of the solid electrolyte membrane in this comparative example is as follows:
[0133] 0.6 g of polyvinylidene fluoride and 0.2 g of lithium salt LiTFSI were mixed to obtain an electrolyte mixture. The electrolyte mixture was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain an electrolyte dispersion. The electrolyte dispersion was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0134] Comparative Example 7
[0135] This comparative example provides a solid electrolyte membrane.
[0136] The preparation method of the solid electrolyte membrane in this comparative example is as follows:
[0137] 0.6 g of polyvinylidene fluoride was dispersed in 3 mL of N,N-dimethylformamide and stirred continuously at 60 °C for 12 h to obtain a solution. The solution was poured into a mold, vacuum degassed in a vacuum drying oven for 1 h, and then dried at 120 °C for 12 h to obtain a solid electrolyte membrane.
[0138] Test case
[0139] The thickness, tensile strength, surface morphology, and ionic conductivity at 25°C of the solid electrolyte membranes in the examples and comparative examples were tested. The test results are shown in Table 1 and... Figures 1-3 , Figure 1 This is a test graph showing the ionic conductivity of the solid electrolyte membrane in Example 1 of this application. Figure 2 These are XRD patterns of PVDF powder from Example 1 and Comparative Examples 1-3 of this application. Figure 3 These are morphological images of the solid electrolyte membranes in Example 1 and Comparative Examples 1-3 of this application.
[0140] The solid electrolyte membranes used in the examples and comparative examples were assembled with lithium iron phosphate cathodes (LFP:SP:PVDF:LATP=70:10:10:10) and lithium sheets to form standard coin cells. Battery performance was tested on the coin cells, and the test results are shown in Table 1. The test conditions were as follows:
[0141] Initial discharge specific capacity test: room temperature, 2.8V~3.65V, 0.1CC / CD.
[0142] Cyclic test: 25℃, 2.8V~3.65V, 1CC / CD, 20 cycles / 50 cycles.
[0143] Table 1 Performance test results of solid electrolyte membranes in the examples and comparative examples
[0144]
[0145] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0146] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.
Claims
1. A method for producing a solid-state electrolyte film based on an ionic liquid modification, characterized by, The method comprises the following steps: mixing an ionic liquid, a polymer, a lithium salt and a solvent to prepare an electrolyte dispersion; drying the electrolyte dispersion into a film to prepare a solid-state electrolyte film; a mass ratio of the ionic liquid to the polymer in the electrolyte dispersion is 1:(0.8-5), and a mass ratio of the lithium salt to the polymer is 1:(0.5-5); the polymer contains a vinylidene fluoride segment; the ionic liquid includes one or more of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide.
2. The method of claim 1, wherein the solid-state electrolyte film is prepared by a method comprising: the polymer includes one or more of polyvinylidene fluoride homopolymer and polyvinylidene fluoride-hexafluoropropylene copolymer; and / or, the average molecular weight of the polymer is 400000-600000.
3. The method of claim 1, wherein the solid-state electrolyte film is prepared by a method comprising: a thickness of the solid-state electrolyte film is 15μm-150μm; and / or The density of the solid-state electrolyte film is 0.2 g / cm 3 0.5 g / cm 3 ; and / or an ionic conductivity of the solid-state electrolyte film at 25℃ is 0.1mS / cm-1.4mS / cm; and / or a tensile strength of the solid-state electrolyte is 0.5MPa-3MPa.
4. The method of claim 1, wherein the solid-state electrolyte film is prepared by a method comprising: the solvent includes one or more of N,N-dimethylformamide, tetrahydrofuran, dimethylacetamide, tetramethylurea, dimethyl sulfoxide, N-methyl pyrrolidone, acetone, cyclohexanone, n-butyl acetate, methyl isobutyl ketone and ethylene glycol diethyl ether.
5. The method of claim 1, wherein the solid-state electrolyte film is prepared by a method comprising: the lithium salt includes one or more of LiPF6, LiClO4, LiAsF6, LiBF4, LiBOB, LiDFOB, LiTFSI, LiFSI, LiPO2F2 and LiTDI.
6. The method of claim 1 to 5, wherein The process for preparing the electrolyte dispersion comprises: mixing an ionic liquid, a polymer and a lithium salt to prepare an electrolyte mixture; continuously stirring the electrolyte mixture with a solvent at 25℃-80℃ for 4h-24h.
7. The method of claim 1 to 5, wherein The process for preparing the solid-state electrolyte film comprises: placing the electrolyte dispersion in a substrate and drying at 25℃-120℃ for 4h-24h to obtain the solid-state electrolyte film.
8. A solid state electrolyte membrane, characterized by, obtained by the method for preparing the solid-state electrolyte film according to any one of claims 1-7.
9. A battery, characterized by a battery comprising a positive electrode and a negative electrode, and the solid-state electrolyte film obtained by the method for preparing the solid-state electrolyte film according to any one of claims 1-7 or the solid-state electrolyte film according to claim 8; the solid-state electrolyte film is arranged between the positive electrode and the negative electrode.
10. An electrical device, characterized by the battery according to claim 9.