Solid-state electrolyte and preparation method thereof, battery

Abstract

The application discloses a solid-state electrolyte and a preparation method and a battery thereof. The solid-state electrolyte comprises a polymer and a lithium salt, and the polymer comprises: wherein, 5<=n<=30, 10<=m<=40. The solid-state electrolyte has good conductivity and mechanical strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a solid-state electrolyte, a preparation method thereof and a battery. BACKGROUND

[0002] To alleviate the energy crisis, the field of green energy is booming. Lithium batteries play an extremely important role in human life, and with the increase of energy density of lithium batteries, there have been many safety accidents caused by fire and explosion of lithium-ion liquid batteries in the world. At present, commercial batteries mostly use flammable organic electrolyte and lithium salt as electrolyte, which not only restricts the safety cycle of the battery, but also affects the development of the new generation of high-energy density batteries with metal lithium as the negative electrode. Solid-state electrolyte has outstanding advantages in heat resistance, mechanical strength and electrochemical stability, which can be expected to be compatible with metal lithium negative electrode to prepare full-solid-state lithium metal high-energy batteries while ensuring safety.

[0003] However, most of the traditional polymer solid-state electrolytes have the shortcomings of poor electrical conductivity and mechanical strength, which limits the application of polymer solid-state electrolytes. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a solid-state electrolyte, a preparation method thereof and a battery, and the solid-state electrolyte provided by the present application has good electrical conductivity and mechanical strength.

[0005] In one aspect of the present application, a solid-state electrolyte is provided. According to an embodiment of the present application, the solid-state electrolyte comprises a polymer and a lithium salt, and the polymer comprises:

[0006]

[0007] wherein 5≤n≤30, 10≤m≤40.

[0008] According to the solid-state electrolyte of the above-mentioned embodiments of the present application, the polymer is a supramolecular structure, wherein non-covalent bonds (hydrogen bonds, pi-pi stacking, etc.) are possessed, the non-covalent bonds have supramolecular forces, and good self-assembly and self-recognition characteristics are possessed. Taking hydrogen bonds as an example, the action of multiple hydrogen bonds can be formed, and the mechanical strength and toughness of the polymer system are greatly enhanced. In addition, the presence of supramolecular forces can promote the polymer to have good interface adaptability, and ensure stable fitting with the electrode interface. In addition, the structure of the polymer comprises repeating units composed of ether oxygen bonds, two six-membered rings and benzene rings. These repeating units form a folding structure, wherein the ether oxygen bonds act as connecting units and can form hydrogen bonds, pi-pi stacking and other interactions with other functional groups, thereby driving the self-assembly of the polymer. The benzene ring and the six-membered ring can provide a rigid skeleton to promote the stabilization of the assembled structure, which is conducive to improving the mechanical strength of the solid-state electrolyte. Moreover, the folding structure of the ether oxygen bond, the six-membered ring and the benzene ring can effectively limit the crystallinity of the polymer to a certain range, thereby reducing the resistance inside the polymer electrolyte, making the transmission of lithium ions in the polymer more smooth, and further improving the electrical conductivity of the solid-state electrolyte. Thus, the solid-state electrolyte of the present application has good electrical conductivity and mechanical strength.

[0009] In addition, the solid-state electrolyte according to the above-mentioned embodiments of the present application can also have the following additional technical features:

[0010] In some embodiments of the present application, the mass percentage of the lithium salt is 5% to 50% based on the total mass of the solid-state electrolyte. Thus, the formation of lithium ion channels can be optimized, and the transmission efficiency and electrical conductivity of lithium ions can be improved.

[0011] In some embodiments of the present application, the lithium salt comprises at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate.

[0012] In some embodiments of the present application, the solid-state electrolyte further comprises an additive. Thus, the chemical species on the electrode surface can be changed, and the interfacial affinity of the electrode and the solid-state electrolyte can be adjusted.

[0013] In some embodiments of the present application, the mass percentage of the additive is 0.5% to 5% based on the total mass of the solid-state electrolyte. Thus, the compatibility of the solid-state electrolyte and the electrode interface can be enhanced, the interface resistance and the formation of lithium dendrites can be reduced, and the cycle stability of the battery can be improved.

[0014] In some embodiments of the present application, the additive comprises fluoroethylene carbonate. Thus, the impedance of the battery can be reduced, the decomposition of part of the solid-state electrolyte can be effectively inhibited, and the stability of the battery can be improved.

[0015] In some embodiments of the present application, the solid-state electrolyte has a thickness of 20 μm to 200 μm. In this way, the ionic conductivity of the solid-state electrolyte can be improved.

[0016] In a second aspect of the present application, a method for preparing the solid-state electrolyte is provided. According to an embodiment of the present application, the method comprises mixing polyethylene glycol, isophorone diisocyanate and a catalyst, heating to perform a first reaction to obtain a prepolymer; mixing the prepolymer, isophthalic dihydrazide and a solvent to perform a second reaction to obtain a polymer solution; mixing the polymer solution with a lithium salt, removing the solvent, and hot-pressing to obtain the solid-state electrolyte. In this way, a solid-state electrolyte with good conductivity and mechanical strength can be obtained.

[0017] In some embodiments of the present application, the molar ratio of the polyethylene glycol to the isophorone diisocyanate is 1:(4-10). In this way, the number and ratio of functional groups participating in the reaction can be controlled, the molecular chain can be smoothly extended, the structure of the polymer can be adjusted, and a suitable molecular structure can be obtained.

[0018] In some embodiments of the present application, the molar ratio of the polyethylene glycol to the isophthalic dihydrazide is 1:(2-5). In this way, the molecular weight of the polymer can be effectively controlled, which helps to prevent excessive cross-linking and branching, maintain the regularity of the molecular chain, and improve the mechanical properties of the polymer.

[0019] In some embodiments of the present application, the molecular weight of the polyethylene glycol is 1000-20000. In this way, the length and flexibility of the polymer molecular chain can be effectively controlled, which is conducive to improving the mechanical strength of the solid-state electrolyte.

[0020] In some embodiments of the present application, the catalyst comprises dibutyltin dilaurate. In this way, the speed of the polymerization reaction can be significantly improved, thereby shortening the reaction time and improving the production efficiency.

[0021] In some embodiments of the present application, the solvent comprises at least one of N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile and tetrahydrofuran. In this way, the solvent can be quickly volatilized and the solid-state electrolyte can be formed during the preparation process due to the faster volatilization speed.

[0022] In some embodiments of the present application, the temperature of the first reaction is 70°C-90°C. In this way, the movement speed of the reaction molecules can be accelerated, and the collision frequency between the molecules can be increased, thereby promoting the polymerization reaction.

[0023] In some embodiments of the present application, the time of the first reaction is 1h-5h. In this way, a molecular chain segment with excellent supermolecular force can be effectively obtained, which is conducive to improving the mechanical strength of the solid-state electrolyte.

[0024] In some embodiments of the present application, the second reaction is performed at a temperature of 10°C to 30°C. In this way, the end reaction of isophthalic dihydrazide with the prepolymer is facilitated, and the rate of the second reaction is increased.

[0025] In some embodiments of the present application, the second reaction is performed for a time period of 20h to 30h. In this way, the end group structure of the polymer molecular chain and the crosslinking degree can be adjusted, and the stability of the polymer is improved.

[0026] In some embodiments of the present application, step S3 comprises mixing the polymer solution, the lithium salt and the additive, and after removing the solvent, hot-pressing to obtain the solid-state electrolyte.

[0027] In some embodiments of the present application, the hot-pressing is performed at a temperature of 50°C to 100°C. In this way, the intermolecular bonding and physical entanglement are facilitated, and the compactness and mechanical strength of the solid-state electrolyte are improved.

[0028] In some embodiments of the present application, the hot-pressing is performed for a time period of 20min to 60min. In this way, the solid-state electrolyte film is formed, and the solid-state electrolyte with uniform thickness is obtained.

[0029] In a third aspect, the present application provides a battery. According to embodiments of the present application, the battery comprises the solid-state electrolyte described above or prepared by the method described above.

[0030] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0032] Figure 1 A flow chart of a method for preparing a solid-state electrolyte according to an embodiment of the present application is shown;

[0033] Figure 2 A picture showing a needle-punching test of a solid-state electrolyte according to Example 1 is shown. DETAILED DESCRIPTION

[0034] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and are intended to explain the present application, and should not be understood as limiting the present application.

[0035] In one aspect of the present application, the present application provides a solid-state electrolyte. According to an embodiment of the present application, the solid-state electrolyte comprises a polymer, the polymer comprising:

[0036]

[0037] wherein 5≤n≤30, 10≤m≤40. For example, n can be 5, 10, 15, 20, 25, 30, etc., and m can be 10, 20, 30, 40, etc.

[0038] According to the solid-state electrolyte of the above-mentioned embodiments of the present application, the polymer is a supramolecular structure, wherein there are non-covalent bonds (hydrogen bonds, π-π stacking, etc.), which have supramolecular forces and good self-assembly and self-recognition characteristics. Taking hydrogen bonds as an example, multiple hydrogen bonds can be formed, which can improve the mechanical strength and toughness of the polymer system. In addition, the presence of supramolecular forces can promote the polymer to have good interface adaptability, ensuring stable fitting with the electrode interface. In addition, the structure of the polymer also contains repeating units composed of ether oxygen bonds, two six-membered rings and benzene rings. These repeating units form a folding structure, wherein the ether oxygen bond as a connecting unit can form hydrogen bonds, π-π stacking and other interactions with other functional groups, thereby driving the self-assembly of the polymer. The benzene ring and the six-membered ring can provide a rigid skeleton to promote the stabilization of the assembly structure, which is conducive to improving the mechanical strength of the solid-state electrolyte. Moreover, the folding structure of the ether oxygen bond, the six-membered ring and the benzene ring can effectively limit the crystallinity of the polymer to a certain range, thereby reducing the resistance inside the polymer electrolyte, making the transport of lithium ions in the polymer more smooth, and thus improving the electrical conductivity of the solid-state electrolyte. Further, by limiting the values of n and m within the above range, the length of the molecular chain can be effectively controlled, and the intermolecular interaction and steric hindrance can be reduced, which is conducive to the migration of lithium ions and can improve the electrical conductivity of the solid-state electrolyte. Thus, the solid-state electrolyte of the present application has good electrical conductivity and mechanical strength, which is conducive to improving the cycle performance of the battery.

[0039] According to some embodiments of the present application, the solid-state electrolyte further comprises a lithium salt. The addition of lithium salt can provide mobile lithium ions in the solid-state electrolyte, which can increase the concentration of lithium ions and thus improve the ionic conductivity of the solid-state electrolyte. On the other hand, it is conducive to the formation of a conductive polymer network to ensure the subsequent operation of the all-solid-state battery.

[0040] According to some embodiments of the present application, the lithium salt accounts for 5% to 50% of the total mass of the solid-state electrolyte. For example, 5%, 10%, 20%, 40%, 50%, etc. By limiting the mass fraction of lithium salt within the above range, the distribution of lithium ions in the polymer can be controlled, the formation of lithium ion channels can be optimized, and the transmission efficiency and conductivity of lithium ions can be improved.

[0041] For example, the lithium salt includes, but is not limited to, at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium hexafluorophosphate (LiPF6).

[0042] According to some embodiments of the present application, the solid-state electrolyte further comprises an additive. The addition of the additive can interact with the electrode surface, change the composition of the solid-state electrolyte interface, and thus adjust the interfacial affinity between the electrode and the solid-state electrolyte.

[0043] According to some embodiments of the present application, the additive accounts for 0.5% to 5% of the total mass of the solid-state electrolyte. For example, 0.5%, 1%, 3%, 4%, 5%, etc. By limiting the mass fraction of the additive within the above range, the compatibility of the solid-state electrolyte and the electrode interface can be enhanced, the interface resistance and the formation of lithium dendrites can be reduced, and thus the cycle stability of the battery can be improved.

[0044] According to some embodiments of the present application, the additive includes fluoroethylene carbonate. Fluoroethylene carbonate can form a solid-state electrolyte interface with a compact structure on the electrode surface, reduce the impedance of the battery, effectively inhibit the decomposition of part of the solid-state electrolyte, and thus improve the stability of the battery.

[0045] According to some embodiments of the present application, the thickness of the solid-state electrolyte is 20 μm to 200 μm. For example, it can be 20 μm, 50 μm, 100 μm, 150 μm, 200 μm, etc. By limiting the thickness of the solid-state electrolyte within the above range, the transmission path of lithium ions can be shortened, the transmission efficiency of lithium ions can be improved, and thus the ionic conductivity of the solid-state electrolyte can be improved.

[0046] It should be noted that the thickness of the solid-state electrolyte refers to the size of the solid-state electrolyte material perpendicular to the plane direction thereof.

[0047] In a second aspect of the present application, a method for preparing the above-mentioned solid-state electrolyte is provided. According to embodiments of the present application, the method comprises:

[0048] S1: mixing polyethylene glycol, isophorone diisocyanate, and a catalyst, and heating to perform a first reaction to obtain a prepolymer.

[0049] In the step, under the action of the catalyst, the polyethylene glycol and isophorone diisocyanate can undergo a polymerization reaction to obtain a prepolymer, and the prepolymer is a supramolecular structure, which has non-covalent bonds (hydrogen bonds, π-π stacking, etc.). The non-covalent bonds have supramolecular forces, and have good self-assembly and self-recognition characteristics. Taking hydrogen bonds as an example, multiple hydrogen bonds can be formed, which greatly enhances the mechanical strength and toughness of the polymer system, and is beneficial to improve the mechanical strength of the solid-state electrolyte. The presence of the supramolecular force can promote the polymer to have good interface adaptability, ensure stable fitting with the electrode interface, make the transmission of lithium ions at the interface more smooth, reduce the transmission resistance, and improve the transmission efficiency of lithium ions.

[0050] According to some embodiments of the present application, the molar ratio of the polyethylene glycol and the isophorone diisocyanate is 1:(4-10). For example, it can be 1:4, 1:10, 1:6, etc. By limiting the molar ratio of the polyethylene glycol and the isophorone diisocyanate within the above range, the number and ratio of functional groups participating in the reaction can be controlled, the molecular chain can be smoothly expanded, the structure of the polymer can be adjusted, and a suitable molecular structure can be obtained.

[0051] According to some embodiments of the present application, the molecular weight of the polyethylene glycol is 1000-20000. For example, it can be 1000, 4000, 10000, 20000, etc. By limiting the molecular weight of the polyethylene glycol within the above range, on the one hand, it can promote the smooth progress of the polymerization reaction with the isophorone diisocyanate. On the other hand, the molecular chain length and flexibility of the polymer can be effectively controlled, which is beneficial to improve the mechanical strength of the solid-state electrolyte.

[0052] According to some embodiments of the present application, the catalyst comprises dibutyltin dilaurate. By selecting the above catalyst, the speed of the polymerization reaction can be significantly improved, thereby shortening the reaction time and improving the production efficiency.

[0053] According to some embodiments of the present application, the temperature of the first reaction is 70°C-90°C. For example, it can be 70°C, 80°C, 90°C, etc. By limiting the temperature of the first reaction within the above range, the movement speed of the reaction molecules can be accelerated, and the collision frequency between the molecules can be increased, thereby promoting the progress of the polymerization reaction.

[0054] According to some embodiments of the present application, the time of the first reaction is 1h-5h. For example, it can be 1h, 2h, 3h, 4h, 5h, etc. By limiting the time of the first reaction within the above range, a molecular chain segment with excellent supramolecular force can be effectively obtained, which is beneficial to improve the mechanical strength of the solid-state electrolyte.

[0055] S2: mixing the prepolymer, isophthalic dihydrazide and solvent to perform a second reaction to obtain a polymer solution.

[0056] In this step, by mixing the prepolymer, isophthalic dihydrazide and solvent, the isophthalic dihydrazide can chemically react with the prepolymer in the solvent to cap the prepolymer. On the one hand, the length of the molecular chain can be controlled, thereby the molecular weight of the polymer can be controlled, which helps to prevent excessive cross-linking and branching, maintain the regularity of the molecular chain and improve the mechanical properties of the polymer. On the other hand, the movement of the molecular chain can be inhibited, the activity of the molecular chain is reduced, and the molecular chains can be prevented from intertwining with each other.

[0057] According to some embodiments of the present application, the molar ratio of the polyethylene glycol to the isophthalic dihydrazide is 1:(2-5). For example, it can be 1:2, 1:3, 1:5, etc. By limiting the molar ratio of the polyethylene glycol to the isophthalic dihydrazide within the above range, the molecular weight of the polymer can be effectively controlled, which helps to prevent excessive cross-linking and branching, maintain the regularity of the molecular chain and improve the mechanical properties of the polymer.

[0058] According to some embodiments of the present application, the solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile and tetrahydrofuran. By selecting the above solvent, the above solvent has a high boiling point and a fast evaporation speed, which is beneficial to the fast evaporation of the solvent and the molding of the solid-state electrolyte in the preparation process.

[0059] According to some embodiments of the present application, the temperature of the second reaction is 10°C-30°C. For example, it can be 10°C, 20°C, 30°C, etc. By limiting the temperature of the second reaction within the above range, the end reaction of the isophthalic dihydrazide and the prepolymer can be promoted, and the rate of the second reaction can be improved.

[0060] According to some embodiments of the present application, the time of the second reaction is 20h-30h. For example, it can be 20h, 25h, 30h, etc. By limiting the time of the second reaction within the above range, the end group structure and the cross-linking degree of the polymer molecular chain can be adjusted, thereby the stability of the polymer can be improved.

[0061] S3: mixing the polymer solution and lithium salt, removing the solvent and hot pressing to obtain a solid-state electrolyte.

[0062] In this step, by mixing the polymer solution and lithium salt, then naturally casting, drying at 60°C, and hot pressing after drying, a solid-state electrolyte can be obtained. The hot pressing can obtain a polymer electrolyte with a smoother surface and a controllable thickness, which helps to enhance the interface contact between the polymer electrolyte and the electrode.

[0063] According to some embodiments of the present application, the mixing in step S3 further comprises an additive, and the method comprises: mixing the polymer solution, the lithium salt and the additive, and after removing the solvent, hot-pressing to obtain the solid-state electrolyte. The addition of the additive can interact with the surface of the electrode, and can change the chemical species on the surface of the electrode, thereby adjusting the interfacial affinity between the electrode and the solid-state electrolyte.

[0064] According to some embodiments of the present application, the temperature of the hot-pressing is 50°C-100°C. For example, it can be 50°C, 60°C, 80°C, 100°C, etc. By limiting the temperature of the hot-pressing within the above range, on the one hand, the intermolecular bonding and physical entanglement can be promoted, and the density and mechanical strength of the solid-state electrolyte can be improved. On the other hand, the movement of the polymer molecular chain segments can be promoted, and the processability of the polymer system can be ensured.

[0065] According to some embodiments of the present application, the time of the hot-pressing is 20min-60min. For example, it can be 20min, 40min, 60min, etc. By limiting the time of the hot-pressing within the above range, on the one hand, the close arrangement and interaction between the polymer molecules can be promoted, which is beneficial to improve the density and mechanical strength of the solid-state electrolyte. On the other hand, it is beneficial to form the solid-state electrolyte film, and to obtain a solid-state electrolyte with uniform thickness.

[0066] According to the method for preparing the solid-state electrolyte according to the embodiments of the present application, after the polymerization reaction of polyethylene glycol and isophorone diisocyanate under the catalysis of dibutyltin dilaurate, a polymer with non-covalent supermolecular force can be obtained. The supermolecular non-covalent bond has good self-assembly and self-recognition characteristics. For example, multiple hydrogen bonds can be formed, which greatly enhances the mechanical strength and toughness of the polymer system. In addition, the existence of supermolecular force can promote the solid-state electrolyte to have good interface adaptability, and ensure stable fitting with the electrode interface. Further, the chemical reaction of the above molecular chain with m-phthaldehyde in a solvent can further control the length of the molecular chain. Too long molecular chains will exhibit large displacement resistance, which is not conducive to the migration of lithium ions between the molecular chains. The all-solid-state polymer electrolyte obtained by the above method has the characteristics of high mechanical strength and high conductivity, and can be directly used as an electrolyte, solving the problems of the use of general organic electrolyte and the low strength and poor conductivity of traditional polymer electrolyte films. At the same time, the method of the present application reduces the operation cost and energy consumption, and ensures the yield of the all-solid-state polymer electrolyte, which is conducive to the realization of industrial production.

[0067] In a third aspect, the present application provides a battery comprising the solid-state electrolyte described above or prepared by the method described above according to embodiments of the present application. Thus, the battery has good stability and safety performance. It should be noted that the features and advantages described above for the solid-state electrolyte and the preparation method thereof also apply to the battery, which will not be described here again.

[0068] Embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in the art or according to the product instructions are used. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0069] Example 1

[0070] Preparation of the solid-state electrolyte:

[0071] 1) Polyethylene glycol, isophorone diisocyanate and dibutyltin dilaurate were mixed and reacted at a temperature of 80°C for 3h to obtain a prepolymer; wherein the molar ratio of polyethylene glycol to isophorone diisocyanate was 1:6;

[0072] 2) The prepolymer, a catalyst m-phenylenediamine and N,N-dimethylformamide were mixed and reacted at a temperature of 20°C for 25h to obtain a polymer solution; wherein the molar ratio of polyethylene glycol to m-phenylenediamine was 1:3;

[0073] 3) The polymer solution, lithium salt lithium bis(trifluoromethanesulfonyl)imide and additive fluoroethylene carbonate were mixed, naturally cast, and then dried at 60°C to remove the solvent, and then hot-pressed at a temperature of 100°C to obtain a solid-state electrolyte with a thickness of 100μm; wherein n of the polymer in the solid-state electrolyte was 20, m was 30, the mass ratio of the lithium salt was 30%, and the mass ratio of the additive was 1%.

[0074] Comparative Example 3

[0075] The solid-state electrolyte was prepared by replacing the polymer with polyethylene oxide, and the rest was the same as Example 1.

[0076] The experimental parameters of Examples 1-17 and Comparative Examples 1-2 of the present application are shown in Table 1.

[0077] Table 1

[0078]

[0079] Testing and analysis

[0080] The solid-state electrolytes prepared in the above Examples 1-17 and Comparative Examples 1-3 were subjected to the pin test and the conductivity test under the same conditions, and the specific test methods were as follows:

[0081] Pin test: The obtained polymer electrolyte membrane was placed on a sharp tweezers, and an external force was applied downward to observe whether the polymer electrolyte membrane was pierced by the sharp tweezers. Figure 2 The picture showing the pin test of the solid-state electrolyte of Example 1 is shown, from which it can be seen that the solid-state electrolyte membrane is not pierced under the action of external force, showing good mechanical strength.

[0082] Conductivity test: The obtained solid-state electrolyte membrane was cut into a circular piece with a diameter of 12 mm, the positive electrode was lithium iron phosphate, the negative electrode was lithium metal, a button cell was assembled, and the resistance of the button cell was tested by using an electrochemical workstation, and the conductivity value was calculated according to the resistance value,

[0083] Conductivity = resistance x cross-sectional area of solid-state electrolyte / length of solid-state electrolyte

[0084] The test results are shown in Table 2.

[0085] Table 2

[0086]

[0087] Results and discussion

[0088] As can be seen from Tables 1-2, compared with Comparative Example 1, the solid-state electrolytes of Examples 1-17 have better conductivity and mechanical strength, and compared with Comparative Example 2, the solid-state electrolytes of Examples 1-17 have better conductivity, which is because the solid-state electrolyte of the present application contains a repeating unit composed of an ether oxygen bond, two six-membered rings and a benzene ring, which forms a folding structure. Among them, the ether oxygen bond as a connecting unit can form hydrogen bonding, π-π stacking and other interactions with other functional groups, thereby driving the self-assembly of the polymer. While the benzene ring and the six-membered ring can provide a rigid skeleton to promote the stabilization of the assembled structure, which is conducive to improving the mechanical strength of the solid-state electrolyte. Moreover, the folding structure of the ether oxygen bond, the six-membered ring and the benzene ring can effectively limit the crystallinity of the polymer, thereby reducing the resistance inside the polymer electrolyte, making the transmission of lithium ions in the polymer more smooth, and thus the conductivity of the solid-state electrolyte can be improved. Thus, the solid-state electrolyte of the present application has good conductivity and mechanical strength.

[0089] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0090] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A solid electrolyte, characterized in that, The solid electrolyte comprises a polymer and a lithium salt, wherein the polymer comprises: Where 5≤n≤30, 10≤m≤40.

2. The solid electrolyte according to claim 1, characterized in that, Based on the total mass of the solid electrolyte, the lithium salt accounts for 5% to 50% of the mass; and / or, The lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium hexafluorophosphate.

3. The solid electrolyte according to claim 1 or 2, characterized in that, The solid electrolyte also includes additives. Based on the total mass of the solid electrolyte, the additive accounts for 0.5% to 5% of the total mass; and / or, The additives include fluoroethylene carbonate.

4. The solid electrolyte according to claim 1 or 2, characterized in that, The thickness of the solid electrolyte is 20μm-200μm.

5. A method for preparing a solid electrolyte according to any one of claims 1-4, characterized in that, include: S1. Mix polyethylene glycol, isophorone diisocyanate and catalyst, and heat to carry out the first reaction to obtain the prepolymer; S2. The prepolymer, isophthalohydrazide and solvent are mixed and reacted a second time to obtain a polymer solution; S3. Mix the polymer solution with lithium salt, remove the solvent, and then hot-press to obtain a solid electrolyte.

6. The method according to claim 5, characterized in that, The molar ratio of the polyethylene glycol to the isophorone diisocyanate is 1:(4-10); and / or, The molar ratio of polyethylene glycol to isophthalic acid hydrazide is 1:(2-5); and / or, The catalyst comprises dibutyltin dilaurate; and / or, The solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, and tetrahydrofuran.

7. The method according to claim 5, characterized in that, The temperature of the first reaction is 70°C-90°C; and / or, The first reaction takes 1-5 hours.

8. The method according to claim 5, characterized in that, The temperature of the second reaction is 10°C-30°C; and / or, The second reaction takes 20-30 hours.

9. The method according to claim 5, characterized in that, Step S3 includes: mixing the polymer solution, lithium salt, and additives, removing the solvent, and then hot-pressing to obtain a solid electrolyte; and / or, The hot pressing temperature is 50°C-100°C; and / or, The hot pressing time is 20-60 minutes.

10. A battery, characterized in that, The battery comprises a solid electrolyte as described in any one of claims 1-3 or a solid electrolyte prepared by any one of claims 5-9.

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