A solid electrolyte and the all-solid-state lithium battery prepared therefrom

Abstract

This invention relates to the field of all-solid-state lithium battery technology, specifically to a solid electrolyte and the all-solid-state lithium battery prepared therefrom. The invention involves uniformly mixing polycarbonate diol and modified diol, adding isophorone diisocyanate and dibutyltin dilaurate under nitrogen protection, reacting at 90-100°C for 2-5 hours, adding dimethylolpropionic acid, a flame retardant, and an organic solvent, reacting at 70-80°C for 4-7 hours, cooling to 40-50°C, adding pentaerythritol tetra-3-mercaptopropionate and a photoinitiator, reacting under ultraviolet light for 1-2 hours, adding triethylamine for neutralization, then adding deionized water for emulsification, removing the organic solvent under reduced pressure to obtain an aqueous polyurethane solution; Step S3: uniformly mixing the aqueous polyurethane solution with a lithium salt, drying, and obtaining a solid electrolyte with high ionic conductivity, excellent high-temperature resistance, and flame retardancy.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state lithium battery technology, specifically to a solid electrolyte and the all-solid-state lithium battery prepared therefrom. Background Technology

[0002] Traditional liquid lithium batteries use liquid electrolytes, which, while offering advantages such as high energy density and long cycle life, pose safety hazards, including flammability and explosiveness. Under extreme conditions, such as overcharging, over-discharging, or high temperatures, liquid electrolytes may experience thermal runaway, leading to fires or explosions. To address the issues of battery leakage and combustion after impact, replacing traditional liquid electrolytes with solid-state electrolytes is crucial. Solid-state electrolytes not only improve battery safety but also possess higher thermal stability and resistance to chemical corrosion. Furthermore, solid-state electrolytes can increase battery energy density and cycle life, and are suitable for a wider temperature range.

[0003] Solid-state electrolytes are mainly divided into two types: inorganic solid-state electrolytes and polymer solid-state electrolytes. Polymer solid-state electrolytes are typically composed of a polymer matrix combined with lithium salts, allowing them to flexibly fill the internal space of the battery. However, polymer solid-state electrolytes can still cause fires after short circuits or mechanical impacts. Furthermore, polymer electrolytes have relatively low ionic conductivity, limiting the battery's charge / discharge rate and energy density.

[0004] Therefore, we propose a solid electrolyte and the all-solid-state lithium battery prepared therefrom. Summary of the Invention

[0005] The purpose of this invention is to provide a solid electrolyte and an all-solid-state lithium battery prepared therefrom, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a solid electrolyte includes the following steps:

[0008] Step S1: Mix the dihalogen compound and tetrahydrofuran evenly, add ethylene glycol and triethylamine under ice bath conditions, heat to 25-35℃, and continue the reaction for 4-6 hours. After filtration, washing and drying, the modified diol is obtained.

[0009] Step S2: Mix polycarbonate diol and modified diol evenly. Under nitrogen protection, add isophorone diisocyanate and dibutyltin dilaurate and mix evenly. React at 90-100℃ for 2-5 hours. Add dimethylolpropionic acid, flame retardant and organic solvent. React at 70-80℃ for 4-7 hours. Cool down to 40-50℃, add pentaerythritol tetra-3-mercaptopropionate and photoinitiator. React under ultraviolet light for 1-2 hours. Add triethylamine for neutralization reaction. Add deionized water for emulsification. Remove organic solvent under reduced pressure to obtain an aqueous polyurethane solution.

[0010] Step S3: Mix the aqueous polyurethane solution and lithium salt evenly, and dry them to obtain a solid electrolyte.

[0011] Furthermore, the solid electrolyte is composed of the following components in parts by weight: 70-90 parts of aqueous polyurethane solution and 10-30 parts of lithium salt.

[0012] Furthermore, the aqueous polyurethane solution is composed of the following components in parts by weight: 40-50 parts of polycarbonate diol, 10-20 parts of modified diol, 60-80 parts of isophorone diisocyanate, 1-3 parts of dibutyltin dilaurate, 2-5 parts of dimethylolpropionic acid, 5-15 parts of flame retardant, 20-40 parts of pentaerythritol tetra-3-mercaptopropionate, 1-3 parts of photoinitiator, 3-5 parts of triethylamine, and 150-250 parts of deionized water.

[0013] Furthermore, the modified diol is composed of the following components in parts by weight: 15-20 parts of dihalogen compound, 40-60 parts of tetrahydrofuran, 6-12 parts of ethylene glycol, and 25-30 parts of triethylamine.

[0014] Furthermore, the preparation method of the dihalogen compound is as follows:

[0015] Under nitrogen protection, phosphorus oxychloride and tetrahydrofuran were mixed evenly, and 2,4-diamino-6-vinyl-S-triazine and triethylamine were added. The mixture was reacted in an ice bath for 2-3 hours, then heated to 25-35°C and reacted for another 4-6 hours. After filtration, washing and drying, the dihalogen compound was obtained.

[0016] Furthermore, the mass ratio of phosphorus oxychloride and tetrahydrofuran, 2,4-diamino-6-vinyl-S-triazine and triethylamine is 1:(4-6):(0.7-0.8):(0.8-1.2).

[0017] Furthermore, the preparation method of the flame retardant is as follows:

[0018] Step (1): Mix the dihalogen compound and tetrahydrofuran evenly, add 2-aminobenzothiazole and triethylamine, react under ice bath conditions for 2-3 hours, raise the temperature to 25-35℃, continue the reaction for 4-6 hours, and after filtration, washing and drying, obtain the intermediate;

[0019] Step (2): Heat the dihydroxy-terminated polysiloxane to 80-100℃, add 4-hydroxyphenylboronic acid and mix evenly, and carry out a vacuum reaction under vacuum conditions to obtain boron-containing organosilicon.

[0020] Step (3): Mix the intermediate and tetrahydrofuran evenly, add boron-containing organosilicon and triethylamine, react under ice bath conditions for 2-3 hours, raise the temperature to 25-35℃, continue the reaction for 4-6 hours, and after filtration, washing and drying, obtain the flame retardant.

[0021] Furthermore, in step (1), the mass ratio of the dihalogen compound, tetrahydrofuran, 2-aminobenzothiazole and triethylamine is 1:(4-6):(0.45-0.55):(0.8-1.2).

[0022] Furthermore, in step (2), the mass ratio of dihydroxy-terminated polysiloxane to 4-hydroxyphenylboronic acid is 1:(0.1-0.3).

[0023] Furthermore, in step (2), the process conditions for the vacuum reaction are: vacuum degree 0.06-0.08MPa, reaction temperature 130-150℃, and reaction time 8-12h.

[0024] Furthermore, in step (3), the mass ratio of the intermediate, tetrahydrofuran, boron-containing organosilicon and triethylamine is 1:(4-6):(1-2):(0.8-1.2).

[0025] In the above technical solution, by controlling the dihalogen compound to be slightly excessive, one of the -Cl in the dihalogen compound reacts with the amino group in 2-aminobenzothiazole to introduce a thiazole structure and obtain an intermediate; then, 4-hydroxyphenylboronic acid reacts with a dihydroxy-terminated polysiloxane to obtain a boron-containing organosilicon; finally, the remaining -Cl in the intermediate reacts with the hydroxyl group of the boron-containing organosilicon, and triethylamine removes the hydrogen chloride generated in the reaction to obtain a flame retardant containing N, S, P, Si, and B elements.

[0026] Furthermore, in step S2, the organic solvent is acetone, and its amount is 3-5 times that of the flame retardant.

[0027] Furthermore, the process conditions for ultraviolet light irradiation are: irradiation wavelength 360-400nm, irradiation intensity 20-35mW / cm². 2 .

[0028] Furthermore, the lithium salt is one or more of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, or lithium hexafluorophosphate.

[0029] Furthermore, in step S3, the drying process includes drying at 60-100℃ for 20-30 hours under vacuum conditions.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. The present invention relates to a solid electrolyte and an all-solid-state lithium battery thereof. By controlling the reaction between one -Cl in phosphorus oxychloride and one amino group in 2,4-diamino-6-vinyl-S-triazine, an amino, vinyl, and triazine structure is introduced to obtain a dihalogen compound. The triazine ring contains nitrogen atoms, which can provide additional electron cloud density, potentially enhancing the interaction between lithium ions and the solid electrolyte and promoting ion transport. Then, a condensation reaction is carried out with ethylene glycol to obtain a modified diol, which can participate in the preparation process of polyurethane. This endows the solid electrolyte with excellent mechanical properties and high-temperature resistance, and can maintain stable dimensional stability at high temperatures, ensuring the safety of lithium-ion batteries operating in high-temperature environments.

[0032] 2. This invention discloses a solid electrolyte and the all-solid-state lithium battery prepared therefrom. The invention utilizes a -Cl group from a dihalogen compound to react with the amino group in 2-aminobenzothiazole, introducing a thiazole structure with good ionic conductivity, which improves the ion mobility in the electrolyte and thus enhances its overall conductivity. Furthermore, the remaining -Cl group from the intermediate reacts with boron-containing organosilicon to obtain a flame retardant containing N, S, P, Si, and B elements. Through the synergistic effect of these multiple elements, the thermal stability and flame retardant properties of the electrolyte are significantly improved, effectively reducing the risk of fire under high temperature or runaway conditions. Simultaneously, this flame retardant contains siloxane segments; the introduction of this structure allows for uniform polymerization of the electrolyte and improves the Li-C14 performance. + Transmission helps improve the cycle performance and energy density of all-solid-state lithium batteries under high current density conditions.

[0033] 3. The solid electrolyte of the present invention and the all-solid-state lithium battery prepared therefrom, by introducing pentaerythritol tetra-3-mercaptopropionate, can undergo a mercapto-alkene click reaction with the double bonds in the modified diol and flame retardant under ultraviolet light irradiation to construct a cross-linked network structure, which not only improves the mechanical strength of the solid electrolyte, but also enhances its heat resistance and overall stability, thereby improving the service life and safety of the lithium battery. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In this embodiment, the polycarbonate diol, catalog number lnb-1163, is sourced from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.; the lithium salt, lithium trifluoromethanesulfonate, CAS number 33454-82-9; and the dihydroxy-terminated polysiloxane, catalog number C303003, is sourced from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0036] In the following examples and comparative examples, 1 part equals 10g.

[0037] Example 1: A method for preparing a solid electrolyte, comprising the following processes:

[0038] Step S1: Mix 15 parts of dihalogen compound and 40 parts of tetrahydrofuran evenly, add 6 parts of ethylene glycol and 25 parts of triethylamine under ice bath conditions, heat to 25°C, and continue the reaction for 4 hours. After filtration, washing and drying, the modified diol is obtained.

[0039] Step S2: Mix 40 parts of polycarbonate diol and 10 parts of modified diol evenly. Under nitrogen protection, add 60 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate and mix evenly. React at 90°C for 2 hours. Add 2 parts of dimethylolpropionic acid, 5 parts of flame retardant and 15 parts of acetone, and react at 70°C for 4 hours. Cool down to 40°C, add 20 parts of pentaerythritol tetra-3-mercaptopropionate and 1 part of photoinitiator, and irradiate with ultraviolet light for 1 hour (irradiation wavelength 360nm, irradiation intensity 20mW / cm). 2 Add 3 parts of triethylamine to neutralize the reaction, then add 150 parts of deionized water to emulsify, remove acetone under reduced pressure to obtain an aqueous polyurethane solution;

[0040] Step S3: Mix 70 parts of aqueous polyurethane solution and 10 parts of lithium salt evenly, and dry at 60°C for 20 hours under vacuum to obtain solid electrolyte;

[0041] The preparation method of dihalogen compounds is as follows:

[0042] Under nitrogen protection, 20 parts of phosphorus oxychloride and 80 parts of tetrahydrofuran were mixed evenly, and 14 parts of 2,4-diamino-6-vinyl-S-triazine and 16 parts of triethylamine were added. The mixture was reacted in an ice bath for 2 hours, then heated to 25°C and reacted for another 4 hours. After filtration, washing and drying, the dihalogen compound was obtained.

[0043] The preparation method of flame retardant is as follows:

[0044] Step (1): Mix 5 parts of dihalogen compound and 20 parts of tetrahydrofuran evenly, add 2.25 parts of 2-aminobenzothiazole and 4 parts of triethylamine, react under ice bath conditions for 2 hours, raise the temperature to 25°C, and continue to react for 4 hours. After filtration, washing and drying, the intermediate is obtained.

[0045] Step (2): Heat 5 parts of dihydroxy-terminated polysiloxane to 80°C, add 0.5 parts of 4-hydroxyphenylboronic acid and mix evenly. Perform a vacuum reaction under vacuum conditions (vacuum degree 0.06MPa, reaction temperature 130°C, reaction time 8h) to obtain boron-containing organosilicon.

[0046] Step (3): Mix 5 parts of intermediate and 20 parts of tetrahydrofuran evenly, add 5 parts of boron-containing organosilicon and 4 parts of triethylamine, react under ice bath conditions for 2 hours, raise the temperature to 25°C, continue to react for 4 hours, and after filtration, washing and drying, obtain flame retardant.

[0047] Example 2: A method for preparing a solid electrolyte, comprising the following processes:

[0048] Step S1: Mix 18 parts of dihalogen compound and 50 parts of tetrahydrofuran evenly, add 10 parts of ethylene glycol and 28 parts of triethylamine under ice bath conditions, heat to 30°C, and continue the reaction for 5 hours. After filtration, washing and drying, the modified diol is obtained.

[0049] Step S2: Mix 45 parts of polycarbonate diol and 15 parts of modified diol evenly. Under nitrogen protection, add 70 parts of isophorone diisocyanate and 2 parts of dibutyltin dilaurate and mix evenly. React at 95°C for 4 hours. Add 3 parts of dimethylolpropionic acid, 10 parts of flame retardant and 40 parts of acetone, and react at 75°C for 5 hours. Cool to 45°C, add 30 parts of pentaerythritol tetra-3-mercaptopropionate and 2 parts of photoinitiator, and irradiate with ultraviolet light for 1.5 hours (irradiation wavelength 380 nm, irradiation intensity 30 mW / cm). 2 Add 4 parts of triethylamine to neutralize the reaction, then add 200 parts of deionized water to emulsify, remove acetone under reduced pressure to obtain an aqueous polyurethane solution;

[0050] Step S3: Mix 80 parts of aqueous polyurethane solution and 20 parts of lithium salt evenly, and dry at 80°C for 25 hours under vacuum to obtain solid electrolyte;

[0051] The preparation method of dihalogen compounds is as follows:

[0052] Under nitrogen protection, 30 parts of phosphorus oxychloride and 150 parts of tetrahydrofuran were mixed evenly, and 22.5 parts of 2,4-diamino-6-vinyl-S-triazine and 30 parts of triethylamine were added. The mixture was reacted in an ice bath for 2.5 h, then heated to 30 °C and reacted for another 5 h. After filtration, washing and drying, the dihalogen compound was obtained.

[0053] The preparation method of flame retardant is as follows:

[0054] Step (1): Mix 10 parts of dihalogen compound and 50 parts of tetrahydrofuran evenly, add 5 parts of 2-aminobenzothiazole and 10 parts of triethylamine, react under ice bath conditions for 2.5 h, raise the temperature to 30 °C, continue the reaction for 5 h, and after filtration, washing and drying, obtain the intermediate.

[0055] Step (2): Heat 15 parts of dihydroxy-terminated polysiloxane to 90°C, add 3 parts of 4-hydroxyphenylboronic acid and mix evenly. Perform a vacuum reaction under vacuum conditions (vacuum degree 0.07MPa, reaction temperature 140°C, reaction time 10h) to obtain boron-containing organosilicon.

[0056] Step (3): Mix 10 parts of intermediate and 50 parts of tetrahydrofuran evenly, add 15 parts of boron-containing organosilicon and 10 parts of triethylamine, react under ice bath conditions for 2.5 h, raise the temperature to 30°C, and continue to react for 5 h. After filtration, washing and drying, the flame retardant is obtained.

[0057] Example 3: A method for preparing a solid electrolyte, comprising the following processes:

[0058] Step S1: Mix 20 parts of dihalogen compound and 60 parts of tetrahydrofuran evenly, add 12 parts of ethylene glycol and 30 parts of triethylamine under ice bath conditions, heat to 35°C, and continue the reaction for 6 hours. After filtration, washing and drying, the modified diol is obtained.

[0059] Step S2: Mix 50 parts of polycarbonate diol and 20 parts of modified diol evenly. Under nitrogen protection, add 80 parts of isophorone diisocyanate and 3 parts of dibutyltin dilaurate and mix evenly. React at 100℃ for 5 hours. Add 5 parts of dimethylolpropionic acid, 15 parts of flame retardant and 75 parts of acetone, and react at 80℃ for 7 hours. Cool to 40-50℃, add 40 parts of pentaerythritol tetra-3-mercaptopropionate and 3 parts of photoinitiator, and irradiate with ultraviolet light for 2 hours (irradiation wavelength 400nm, irradiation intensity 35mW / cm). 2 Add 5 parts of triethylamine to neutralize the reaction, then add 250 parts of deionized water to emulsify, remove the organic solvent under reduced pressure, and obtain an aqueous polyurethane solution.

[0060] Step S3: Mix 90 parts of aqueous polyurethane solution and 30 parts of lithium salt evenly, and dry at 100°C for 30 hours under vacuum to obtain solid electrolyte;

[0061] The preparation method of dihalogen compounds is as follows:

[0062] Under nitrogen protection, 40 parts of phosphorus oxychloride and 240 parts of tetrahydrofuran were mixed evenly, and 32 parts of 2,4-diamino-6-vinyl-S-triazine and 48 parts of triethylamine were added. The mixture was reacted in an ice bath for 3 hours, then heated to 35°C and reacted for another 6 hours. After filtration, washing and drying, the dihalogen compound was obtained.

[0063] The preparation method of flame retardant is as follows:

[0064] Step (1): Mix 15 parts of dihalogen compound and 90 parts of tetrahydrofuran evenly, add 8.25 parts of 2-aminobenzothiazole and 18 parts of triethylamine, react under ice bath conditions for 3 hours, raise the temperature to 35°C, and continue to react for 6 hours. After filtration, washing and drying, the intermediate is obtained.

[0065] Step (2): Heat 30 parts of dihydroxy-terminated polysiloxane to 100°C, add 9 parts of 4-hydroxyphenylboronic acid and mix evenly. Perform a vacuum reaction under vacuum conditions (vacuum degree 0.08MPa, reaction temperature 150°C, reaction time 12h) to obtain boron-containing organosilicon.

[0066] Step (3): Mix 15 parts of intermediate and 90 parts of tetrahydrofuran evenly, add 30 parts of boron-containing organosilicon and 18 parts of triethylamine, react under ice bath conditions for 3 hours, raise the temperature to 35°C, and continue to react for 6 hours. After filtration, washing and drying, the flame retardant is obtained.

[0067] Comparative Example 1: A method for preparing a solid electrolyte, comprising the following processes:

[0068] Step S1: Mix 18 parts of dihalogen compound and 50 parts of tetrahydrofuran evenly, add 10 parts of ethylene glycol and 28 parts of triethylamine under ice bath conditions, heat to 30°C, and continue the reaction for 5 hours. After filtration, washing and drying, the modified diol is obtained.

[0069] Step S2: Mix 45 parts of polycarbonate diol and 15 parts of modified diol evenly. Under nitrogen protection, add 70 parts of isophorone diisocyanate and 2 parts of dibutyltin dilaurate and mix evenly. React at 95°C for 4 hours. Add 3 parts of dimethylolpropionic acid and 40 parts of acetone, and react at 75°C for 5 hours. Cool to 45°C, add 30 parts of pentaerythritol tetra-3-mercaptopropionate and 2 parts of photoinitiator, and irradiate with ultraviolet light for 1.5 hours (irradiation wavelength 380 nm, irradiation intensity 30 mW / cm). 2 Add 4 parts of triethylamine to neutralize the reaction, then add 200 parts of deionized water to emulsify, remove acetone under reduced pressure to obtain an aqueous polyurethane solution;

[0070] Step S3: Mix 80 parts of aqueous polyurethane solution and 20 parts of lithium salt evenly, and dry at 80°C for 25 hours under vacuum to obtain solid electrolyte;

[0071] Compared with Example 2, Comparative Example 1 did not add flame retardant, but the other steps were the same as in Example 2.

[0072] Comparative Example 2: A method for preparing a solid electrolyte, comprising the following processes:

[0073] Step S1: Mix 45 parts of polycarbonate diol and 15 parts of ethylene glycol evenly. Under nitrogen protection, add 70 parts of isophorone diisocyanate and 2 parts of dibutyltin dilaurate and mix evenly. React at 95°C for 4 hours. Add 3 parts of dimethylolpropionic acid, 10 parts of flame retardant, and 40 parts of acetone. React at 75°C for 5 hours. Cool to 45°C, add 30 parts of pentaerythritol tetra-3-mercaptopropionate and 2 parts of photoinitiator. Irradiate with ultraviolet light for 1.5 hours (irradiation wavelength 380 nm, irradiation intensity 30 mW / cm²). 2 Add 4 parts of triethylamine to neutralize the reaction, then add 200 parts of deionized water to emulsify, remove acetone under reduced pressure to obtain an aqueous polyurethane solution;

[0074] Step S2: Mix 80 parts of aqueous polyurethane solution and 20 parts of lithium salt evenly, and dry at 80°C for 25 hours under vacuum to obtain solid electrolyte;

[0075] Compared with Example 2, Comparative Example 2 replaced the modified diol with the same mass of ethylene glycol, and the other steps were the same as in Example 2.

[0076] Comparative Example 3: A method for preparing a solid electrolyte, comprising the following processes:

[0077] Compared to Example 2, Comparative Example 3 will not add pentaerythritol tetra-3-mercaptopropionate, and the other steps will be the same as in Example 2.

[0078] Experiment: 1. Solid electrolytes obtained in Examples 1-3 and Comparative Examples 1-3 were used to prepare samples. Their performance was tested and the results recorded: Vertical combustion test: Tested according to GB / T 2408-2021 "Determination of Combustion Performance of Plastics - Horizontal and Vertical Methods"; Ionic conductivity test: Electrochemical impedance spectroscopy (EIS) of the solid electrolyte was performed using an electrochemical workstation, with a test frequency range of 1.0 × 10⁻⁶. -2 -1.0×10 5 The frequency is Hz, the amplitude is 7mV, and the measurement temperature range is 25-100℃. The conductivity is then calculated using the formula σ=L / (R×S), where σ is the ionic conductivity, L is the thickness of the electrolyte membrane, R is the impedance, and S is the effective area of ​​the electrode.

[0079] 2. Using lithium iron phosphate (LFP) as the positive electrode and lithium sheet as the negative electrode, and the solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-3, a 2032 type button cell was assembled. The capacity retention rate was tested after 100 cycles at 1C rate, and the voltage range was 2.8-4.5V.

[0080] The test results are as follows:

[0081]

[0082] Based on the data in the table above, the following conclusions can be clearly drawn:

[0083] Compared with Examples 1-3, the flame retardant properties, ionic conductivity and capacity retention of the product obtained in Comparative Example 1 all decreased, indicating that the flame retardant prepared by the present invention can effectively improve the safety and performance of the battery.

[0084] Compared with Examples 1-3, the ionic conductivity and capacity retention of the products obtained in Comparative Examples 2 and 3 both decreased, indicating that the modified diol prepared in this invention improves the conductivity of lithium ions by introducing polar groups (such as amino and vinyl groups) and triazine structures to enhance intermolecular interactions. At the same time, this invention enhances the overall performance of the solid electrolyte by adding pentaerythritol tetra-3-mercaptopropionate to increase crosslinking density and optimize ion migration channels.

[0085] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a solid electrolyte, characterized in that: Includes the following steps: Step S1: Mix the dihalogen compound and tetrahydrofuran evenly, add ethylene glycol and triethylamine under ice bath conditions, heat to 25-35℃, and continue the reaction for 4-6 hours. After filtration, washing and drying, the modified diol is obtained. Step S2: Mix polycarbonate diol and modified diol evenly. Under nitrogen protection, add isophorone diisocyanate and dibutyltin dilaurate and mix evenly. React at 90-100℃ for 2-5 hours. Add dimethylolpropionic acid, flame retardant and organic solvent. React at 70-80℃ for 4-7 hours. Cool down to 40-50℃, add pentaerythritol tetra-3-mercaptopropionate and photoinitiator. React under ultraviolet light for 1-2 hours. Add triethylamine for neutralization reaction. Add deionized water for emulsification. Remove organic solvent under reduced pressure to obtain an aqueous polyurethane solution. Step S3: Mix the aqueous polyurethane solution and lithium salt evenly, and dry to obtain a solid electrolyte; The flame retardant is prepared as follows: Step (1): Mix the dihalogen compound and tetrahydrofuran evenly, add 2-aminobenzothiazole and triethylamine, react under ice bath conditions for 2-3 hours, raise the temperature to 25-35℃, continue the reaction for 4-6 hours, and after filtration, washing and drying, obtain the intermediate; Step (2): Heat the dihydroxy-terminated polysiloxane to 80-100℃, add 4-hydroxyphenylboronic acid and mix evenly, and carry out a vacuum reaction under vacuum conditions to obtain boron-containing organosilicon. Step (3): Mix the intermediate and tetrahydrofuran evenly, add boron-containing organosilicon and triethylamine, react under ice bath conditions for 2-3 hours, raise the temperature to 25-35℃, continue the reaction for 4-6 hours, and after filtration, washing and drying, obtain the flame retardant; The preparation method of the dihalogen compound is as follows: Under nitrogen protection, phosphorus oxychloride and tetrahydrofuran were mixed evenly, and 2,4-diamino-6-vinyl-S-triazine and triethylamine were added. The mixture was reacted in an ice bath for 2-3 hours, then heated to 25-35°C and reacted for another 4-6 hours. After filtration, washing and drying, the dihalogen compound was obtained.

2. The method for preparing a solid electrolyte according to claim 1, characterized in that: In step S3, by weight, there are 70-90 parts of aqueous polyurethane solution and 10-30 parts of lithium salt.

3. The method for preparing a solid electrolyte according to claim 2, characterized in that: In step S2, by weight, there are 40-50 parts of polycarbonate diol, 10-20 parts of modified diol, 60-80 parts of isophorone diisocyanate, 1-3 parts of dibutyltin dilaurate, 2-5 parts of dimethylolpropionic acid, 5-15 parts of flame retardant, 20-40 parts of pentaerythritol tetra-3-mercaptopropionate, 1-3 parts of photoinitiator, 3-5 parts of triethylamine, and 150-250 parts of deionized water.

4. The method for preparing a solid electrolyte according to claim 3, characterized in that: In step S1, by weight, there are 15-20 parts of dihalogen compound, 40-60 parts of tetrahydrofuran, 6-12 parts of ethylene glycol, and 25-30 parts of triethylamine.

5. The method for preparing a solid electrolyte according to claim 1, characterized in that: In the preparation method of the dihalogen compound, the mass ratio of phosphorus oxychloride and tetrahydrofuran, 2,4-diamino-6-vinyl-S-triazine and triethylamine is 1:(4-6):(0.7-0.8):(0.8-1.2).

6. The solid electrolyte according to claim 1 and the all-solid-state lithium battery prepared therefrom, characterized in that: In step (3), the mass ratio of the intermediate, tetrahydrofuran, boron-containing organosilicon and triethylamine is 1:(4-6):(1-2):(0.8-1.2).

7. The solid electrolyte and the all-solid-state lithium battery prepared therefrom according to claim 1, characterized in that: The lithium salt is one or more of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, or lithium hexafluorophosphate.

8. An all-solid-state lithium battery, characterized in that: The all-solid-state lithium battery contains a solid electrolyte as described in any one of claims 1-7.

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