Solid-state electrolyte, solid-state battery, preparation method of solid-state battery and electric device
The solid electrolyte composed of lithium bistrifluoromethylsulfonimide and trifluoroethylphenylsulfone solves the problems of insufficient conductivity and interface compatibility, improves the conductivity and flame retardant performance of solid-state batteries, and achieves higher cycle stability and safety.
Patent Information
- Application Number
- CN202510513368.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2025-08-12
AI Technical Summary
The existing solid electrolytes have problems such as insufficient conductivity and fast cycling performance decay, especially at low temperatures, and the interface compatibility of traditional electrolytes is insufficient.
The solid electrolyte composed of lithium bistrifluoromethylsulfonylimide and trifluoroethylphenylsulfonyl is prepared by melt mixing, and the combination of trifluoroethylphenylsulfonyl and bistrifluoromethylsulfonylimide is used to optimize the lithium ion transmission path and interface compatibility, and improve conductivity and flame retardant performance.
It achieves high conductivity, excellent flame retardant performance and interface compatibility, and improves the cycle stability and safety of solid-state batteries.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of battery technology, and in particular to a solid electrolyte, a solid-state battery, a preparation method thereof, and an electrical device. Background Art
[0002] Solid-state batteries primarily consist of solid-state electrodes (positive and negative) and a solid-state electrolyte, completely or partially replacing the liquid electrolyte and separator in traditional lithium-ion batteries. The operating principle of solid-state batteries is similar to that of traditional lithium-ion batteries. During charging, lithium ions migrate from the positive electrode to the negative electrode through the solid-state electrolyte. During discharge, the process reverses, with electrons flowing through an external circuit to form an electric current.
[0003] Compared to traditional lithium-ion batteries, solid-state batteries use solid electrolytes, which are non-flammable and reduce the risk of thermal runaway. Traditional solid electrolytes, such as sulfide and oxide systems, while flame-retardant, still suffer from issues such as insufficient electrical conductivity, leading to rapid degradation of cycling performance. Summary of the Invention
[0004] Based on this, the present application provides a solid electrolyte and a preparation method thereof to improve problems such as insufficient electrical conductivity of the solid electrolyte, thereby improving the cycle performance of the solid-state battery using the solid electrolyte.
[0005] In addition, the present application also provides a solid-state battery, a preparation method thereof, and an electrical device.
[0006] In a first aspect, the present application provides a solid electrolyte comprising lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
[0007] In some embodiments, the solid electrolyte consists of lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
[0008] In some embodiments, the mass ratio of the lithium bis(trifluoromethylsulfonyl)imide to the trifluoroethylphenylsulfone is 1:6-10.
[0009] In some embodiments, the mass ratio of the lithium bis(trifluoromethylsulfonyl)imide to the trifluoroethylphenylsulfone is 1:7-9.
[0010] A second aspect of the present application provides a method for preparing a solid electrolyte, comprising the following steps:
[0011] The solid electrolyte is prepared by melting and mixing lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
[0012] In some embodiments, the temperature of the melt mixing is 150°C to 160°C.
[0013] The third aspect of the present application provides the use of the solid-state electrolyte described above or the solid-state electrolyte prepared by the method for preparing the solid-state electrolyte described above in the preparation of a solid-state battery.
[0014] In a fourth aspect, the present application provides a solid-state battery comprising a positive electrode, an electrolyte layer and a negative electrode, wherein the electrolyte layer comprises the solid-state electrolyte described above or a solid-state electrolyte prepared by the method for preparing the solid-state electrolyte described above.
[0015] A fifth aspect of the present application provides a method for preparing a solid-state battery, the method comprising the following steps:
[0016] The positive electrode, the electrolyte layer and the negative electrode are stacked and assembled in sequence to prepare the solid-state battery; the electrolyte layer includes the solid-state electrolyte described above or a solid-state electrolyte prepared by the preparation method of the solid-state electrolyte described above.
[0017] In a sixth aspect, the present application provides an electrical device comprising a solid-state battery as described above or a solid-state battery produced by the method for producing a solid-state battery as described above.
[0018] The solid electrolyte described in this application has the following beneficial effects:
[0019] The solid electrolyte described in the present application has the advantage of high electrical conductivity due to the coordination of trifluoroethylphenylsulfone and lithium bis(trifluoromethylsulfonyl)imide.
[0020] At the same time, the terminal trifluoromethyl group of trifluoroethylphenyl sulfone releases CF3 free radicals at high temperature and forms a fluorine-containing carbon layer, which can enhance flame retardancy and make the solid electrolyte have excellent flame retardant properties; the sulfone group of trifluoroethylphenyl sulfone and the sulfonyl imide group of lithium bis(trifluoromethylsulfonyl imide) optimize the lithium ion transmission path through multidentate coordination, and the trifluoromethyl group contained in trifluoroethylphenyl sulfone interacts with the dipole of lithium salt anions to enhance lithium ion conduction, making the solid electrolyte have high conductivity; the trifluoroethyl flexible chain segment contained in trifluoroethylphenyl sulfone can also buffer the interface stress through low rotation barrier and improve interface compatibility. DETAILED DESCRIPTION
[0021] To facilitate understanding of the present application, the present application will be described more fully below in conjunction with the specific embodiments. Preferred embodiments of the present application are provided in the specific embodiments. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.
[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0023] Unless otherwise specified or incompatible therewith, terms and phrases used in this application shall have the following meanings:
[0024] In this application, the terms "further," "further," "particularly," "for example," "such as," "example," and "for example" are used for descriptive purposes to indicate that the preceding and following technical solutions are related in terms of their coverage, but should not be construed as limiting the preceding technical solution or the scope of protection of this document. In this document, unless otherwise specified, "A (such as B)" means that B is a non-limiting example of A, and it is understood that A is not limited to B.
[0025] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel options of "with" or "without". If multiple "optional" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent. In this application, descriptions such as "optionally contain" and "optionally include" mean "containing or not containing". "Optional component X" means the presence or absence of component X, or means containing or not containing component X.
[0026] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed in this application should be understood to include any and all subranges subsumed therein.
[0027] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.
[0028] The terms "including," "having," and any variations thereof in the embodiments of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not limited to the listed steps or units but may optionally include steps or units not listed, or may optionally include other steps or components inherent to the process, method, product, or apparatus.
[0029] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.
[0030] Compared to traditional lithium-ion batteries, solid-state batteries utilize solid electrolytes, which are non-flammable and reduce the risk of thermal runaway. While a conventional solid-state electrolyte composed of diphenyl sulfone and lithium bis(trifluoromethylsulfonyl)imide offers many advantages, it also suffers from shortcomings such as insufficient interfacial compatibility and a sharp drop in conductivity at low temperatures (<30°C).
[0031] Based on this, in a first aspect, the present application provides a solid electrolyte comprising lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
[0032] The solid electrolyte has the advantage of high electrical conductivity due to the coordination of trifluoroethylphenylsulfone and lithium bis(trifluoromethylsulfonyl)imide.
[0033] At the same time, the trifluoromethyl group at the end of trifluoroethylphenylsulfone releases CF3 free radicals at high temperatures and forms a fluorine-containing carbon layer, which can enhance flame retardancy and make the solid electrolyte have excellent flame retardant properties; the sulfone group of trifluoroethylphenylsulfone and the sulfonyl imide group (-N(SO2CF3)2) of lithium bis(trifluoromethylsulfonyl imide) optimize the lithium ion transmission path through multidentate coordination, and the trifluoromethyl group (-CF3) contained in trifluoroethylphenylsulfone and the lithium salt anion (TFSI - ) interact with each other, improving lithium ion conduction and making solid-state electrolysis have high conductivity; the trifluoroethyl (-CH2-CF3) flexible chain segment contained in trifluoroethyl phenyl sulfone can also buffer the interfacial stress through low rotation barrier and improve interfacial compatibility.
[0034] Trifluoroethyl phenyl sulfone, also known as phenyl trifluoroethyl sulfone, ((2,2,2-trifluoroethyl)sulfonyl)benzene, etc. Its chemical formula is C8H7F3O2S, and its structural formula is: .
[0035] Lithium bis(trifluoromethanesulfonyl imide), also known as lithium bis(trifluoromethanesulfonyl imide), lithium trifluoromethanesulfonyl imide, etc. Its structural formula is .
[0036] In some embodiments, the solid electrolyte consists of lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
[0037] In some embodiments, in the solid electrolyte, the mass ratio of the lithium bis(trifluoromethylsulfonyl)imide to the trifluoroethylphenylsulfone is 1:6 to 10. It is understood that the mass ratio of the lithium bis(trifluoromethylsulfonyl)imide to the trifluoroethylphenylsulfone includes, but is not limited to, 1:6, 1:7, 1:8, 1:9, and 1:10; in some examples, the mass ratio may be within a range consisting of any two of these values as endpoints, the same below.
[0038] In some examples, in the solid electrolyte, the mass ratio of the lithium bis(trifluoromethylsulfonyl)imide to the trifluoroethylphenylsulfone is 1:7-9.
[0039] In a specific embodiment, in the solid electrolyte, the mass ratio of lithium bis(trifluoromethylsulfonyl)imide to trifluoroethylphenylsulfone is 1:8.
[0040] In some embodiments, the mass content of lithium bis(trifluoromethylsulfonyl)imide in the solid electrolyte is 8% to 15%. Exemplarily, it can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%. In some embodiments, the mass content of trifluoroethylphenylsulfone in the solid electrolyte is 85% to 92%. Exemplarily, it can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, or 92%.
[0041] In some embodiments, the solid electrolyte comprises lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone, which are melt-mixed.
[0042] A second aspect of the present application provides a method for preparing a solid electrolyte, comprising the following steps:
[0043] The solid electrolyte is prepared by melting and mixing lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
[0044] The solid electrolyte preparation method is to prepare the solid electrolyte by melt-mixing lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone, thereby achieving a solid electrolyte with high electrical conductivity. The preparation method has the advantage of being simple in preparation process.
[0045] In some embodiments, the temperature of the melt mixing is 150°C to 160°C.
[0046] In some embodiments, the melt mixing is vacuum melt mixing, and the vacuum melting operation can be performed in a glove box.
[0047] In some specific embodiments, the vacuum degree of the vacuum melt mixing is less than 20 mbar, for example, 10 mbar, 15 mbar, 20 mbar, etc.
[0048] It is understood that the temperature of the melt mixing includes but is not limited to 150°C, 152°C, 154°C, 155°C, 158°C, 159°C, and 160°C.
[0049] In some specific embodiments, in the method for preparing the solid electrolyte, the mixing temperature is 155°C.
[0050] It can be understood that the above-mentioned solid electrolyte can be prepared by the preparation method of the solid electrolyte described in this application.
[0051] The third aspect of the present application provides the use of the solid-state electrolyte described above or the solid-state electrolyte prepared by the method for preparing the solid-state electrolyte described above in the preparation of a solid-state battery.
[0052] In a fourth aspect, the present application provides a solid-state battery comprising a positive electrode, an electrolyte layer and a negative electrode, wherein the electrolyte layer comprises the solid-state electrolyte described above or a solid-state electrolyte prepared by the method for preparing the solid-state electrolyte described above.
[0053] Furthermore, the positive electrode, the electrolyte layer and the negative electrode are stacked in sequence.
[0054] In some embodiments, the positive electrode can be a common positive electrode in the art that can be used in solid-state electrolytes. In some embodiments, in solid-state batteries, the active material in the positive electrode includes at least one of LFP (lithium iron phosphate), NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LCO (lithium cobalt oxide), and LMO (lithium manganese oxide).
[0055] In some embodiments, the negative electrode may be a common negative electrode in the art that can be used for solid electrolytes. In some embodiments, in a solid-state battery, the negative electrode includes at least one of metallic lithium foil, graphite, and lithium titanate.
[0056] It can be understood that metallic lithium foil can be directly used as a current collector without the need for other negative electrode active materials; graphite and lithium titanate are provided as negative electrode active materials on the surface of other current collectors, which include but are not limited to copper foil.
[0057] In some embodiments, the above-mentioned solid-state battery, including the above-mentioned solid-state electrolyte or the solid-state electrolyte prepared by the above-mentioned solid-state electrolyte preparation method, can give the solid-state battery higher ionic conductivity, as well as better stability and better flame retardant properties.
[0058] A fifth aspect of the present application provides a method for preparing a solid-state battery, the method comprising the following steps:
[0059] The positive electrode, the electrolyte layer and the negative electrode are stacked and assembled in sequence to prepare the solid-state battery; the electrolyte layer includes the solid-state electrolyte described above or a solid-state electrolyte prepared by the preparation method of the solid-state electrolyte described above.
[0060] It can be understood that the preparation method of the solid-state battery provided in the present application adopts the above-mentioned solid-state electrolyte or the solid-state electrolyte prepared by the above-mentioned preparation method of the solid-state electrolyte, which improves the flame retardancy, ionic conductivity and stability of the solid-state battery.
[0061] It is understandable that the present application does not limit the preparation method of the solid-state battery, and conventional methods in the art can be used for preparation.
[0062] In a sixth aspect, the present application provides an electrical device comprising a solid-state battery as described above or a solid-state battery produced by the method for producing a solid-state battery as described above.
[0063] As can be understood, solid-state batteries can be used as power sources or energy storage units for electrical devices. Electrical devices may include, but are not limited to, mobile devices, electric vehicles, electric trains, ships, satellites, and energy storage systems. Examples of mobile devices include, but are not limited to, mobile phones and laptops; and examples of electric vehicles include, but are not limited to, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, and electric trucks.
[0064] The electrical device provided in this application includes the above-mentioned solid-state battery and can achieve the same effect as the above-mentioned solid-state battery.
[0065] Example
[0066] Below, the embodiment of the present application is described. The embodiment described below is exemplary, is only used to explain the present application, and is not to be construed as limiting the present application. Where the technology or conditions are not specified in the embodiment, the technology or conditions described in the literature in this area or the product instructions are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.
[0067] Example 1
[0068] Lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and trifluoroethylphenylsulfone (PTFES) in a mass ratio of 1:8 were melt-mixed in a vacuum glove box at a temperature of 155°C and a vacuum degree of 10 mbar, and then cured at room temperature to prepare a solid electrolyte membrane layer.
[0069] Example 2
[0070] Lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone in a mass ratio of 1:10 were melt-mixed in a vacuum glove box at a temperature of 155° C. and a vacuum degree of 10 mbar, and then cured at room temperature to prepare a solid electrolyte membrane layer.
[0071] Example 3
[0072] Lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone in a mass ratio of 1:6 were melt-mixed in a vacuum glove box at a temperature of 155° C. and a vacuum degree of 10 mbar, and then cured at room temperature to prepare a solid electrolyte membrane layer.
[0073] Comparative Example 1
[0074] The method is basically the same as Example 1, except that trifluoroethylphenylsulfone is replaced with diphenylsulfone (DS) of equal mass, as follows:
[0075] Lithium bis(trifluoromethylsulfonyl)imide and DS in a mass ratio of 1:8 were melt-mixed in a vacuum glove box at a temperature of 155°C and a vacuum degree of 10 mbar, and solidified at room temperature to prepare a solid electrolyte membrane layer.
[0076] Test Case
[0077] The solid electrolytes prepared in the examples and comparative examples, the lithium iron phosphate positive electrode, and lithium metal were assembled into solid-state batteries, which were respectively recorded as the solid-state batteries of Examples 1 to 3 and Comparative Example 1.
[0078] The ionic conductivity at 25°C was tested using AC impedance spectroscopy. The frequency range during the test was 0.1 Hz-1 MHz. The test results are shown in Table 1.
[0079] The interface impedance growth rate was obtained by EIS analysis after 100 cycles at 0.1C, and the results are shown in Table 1.
[0080] Table 1
[0081]
[0082] As shown in Table 1, compared with the comparative example, the embodiment has higher ionic conductivity and interface stability by mixing lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone in a specific ratio. In the absence of other solvents, polymers and additives, the ionic conductivity of the electrolyte is as high as 2.1×10-4 S / cm, and the interface growth rate can be as low as 0.12Ω / turn, and the interface compatibility is good.
[0083] Comparative Example 2
[0084] Commercial liquid carbonate electrolyte (LCE, 1 M LiPF6 dissolved in EC / DEC / DMC).
[0085] The flame retardancy of the solid electrolytes prepared in each embodiment and comparative example 1 was tested, and the self-extinguishing time at 200° C. of the electrolytes prepared in each embodiment and comparative examples 1-2 was tested. The results are shown in Table 2.
[0086] The flame retardancy rating is tested using the UL94 rating system. The UL94 Vertical Burning Test (VTM) tests the flame retardancy of a material in the vertical direction. The ratings are categorized as V-0, V-1, and V-2. V-0 means the self-extinguishing time after a single flame application is ≤10 seconds; the total self-extinguishing time after two flame applications is ≤50 seconds, and there is no burning dripping that ignites the cotton underneath. V-1 means the self-extinguishing time after a single flame application is ≤30 seconds, and the total self-extinguishing time after two flame applications is ≤250 seconds. Dripping is permitted but will not ignite the cotton. V-2 has the same self-extinguishing time as V-1, but allows dripping to ignite the cotton.
[0087] The 200℃ self-extinguishing time refers to the time required for the material to completely stop burning after being pretreated at a high temperature of 200℃ and contacting an ignition source.
[0088] Table 2
[0089]
[0090] Among them, / means no rating.
[0091] As shown in Table 2, compared with the comparative example, the solid electrolyte prepared in the embodiment has a higher flame retardant grade and a shorter self-extinguishing time, indicating that the electrolyte in the embodiment has better flame retardant properties by combining lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
[0092] The solid electrolyte provided in this application breaks through the "high safety-high conductivity" contradiction of existing solid electrolytes, has high conductivity, high flame retardancy and excellent interface compatibility.
[0093] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.
[0094] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.
Claims
1. A solid electrolyte, characterized in that The solid electrolyte includes lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
2. The solid electrolyte according to claim 1, characterized in that The solid electrolyte consists of lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
3. The solid electrolyte according to claim 1 or 2, characterized in that The mass ratio of the lithium bis(trifluoromethylsulfonyl)imide to the trifluoroethylphenylsulfone is 1:6-10.
4. The solid electrolyte according to claim 1 or 2, characterized in that The mass ratio of the lithium bis(trifluoromethylsulfonyl)imide to the trifluoroethylphenylsulfone is 1:7-9.
5. A method for preparing a solid electrolyte, characterized in that: The method comprises the following steps: The solid electrolyte is prepared by melting and mixing lithium bis(trifluoromethylsulfonyl)imide and trifluoroethylphenylsulfone.
6. The preparation method according to claim 5, characterized in that The temperature of the melt mixing is 150°C to 160°C.
7. Use of the solid electrolyte according to any one of claims 1 to 4 or the solid electrolyte prepared by the method for preparing the solid electrolyte according to claim 5 or 6 in preparing a solid-state battery.
8. A solid-state battery, characterized in that: The invention comprises a positive electrode, an electrolyte layer and a negative electrode, wherein the electrolyte layer comprises the solid electrolyte according to any one of claims 1 to 4 or the solid electrolyte prepared by the preparation method of the solid electrolyte according to claim 5 or 6.
9. A method for preparing a solid-state battery, characterized in that: The steps include: The positive electrode, the electrolyte layer and the negative electrode are stacked and assembled in sequence to prepare the solid-state battery, wherein the electrolyte layer includes the solid electrolyte according to any one of claims 1 to 5 or the solid electrolyte prepared by the preparation method of the solid electrolyte according to claim 5 or 6.
10. An electrical device, characterized in that: Including a solid-state battery as claimed in claim 8 or a solid-state battery prepared by the preparation method of the solid-state battery as claimed in claim 9.