Solid electrolyte and all-solid-state lithium battery prepared from same

Abstract

The invention relates to the technical field of all-solid-state lithium batteries, in particular to a solid electrolyte and an all-solid-state lithium battery prepared from the same. The preparation method comprises the following steps: uniformly mixing polycarbonate dihydric alcohol and modified dihydric alcohol, adding isophorone diisocyanate and dibutyltin dilaurate under the protection of nitrogen, uniformly mixing, reacting at 90-100 DEG C for 2-5 hours, adding dimethylolpropionic acid, a flame retardant and an organic solvent, reacting at 70-80 DEG C for 4-7 hours, cooling to 40-50 DEG C, carrying out heat preservation for 2-3 hours, and carrying out heat preservation for 2-3 hours. Adding pentaerythritol tetra-3-mercaptopropionate and a photoinitiator, carrying out an ultraviolet irradiation reaction for 1-2 h, adding triethylamine for a neutralization reaction, adding deionized water for emulsification, and carrying out pressure reduction to remove an organic solvent so as to obtain a waterborne polyurethane solution; and S3, uniformly mixing the aqueous polyurethane solution and a lithium salt, and drying to obtain the solid electrolyte with relatively high ionic conductivity, excellent high temperature resistance and flame retardance.

Description

Technical Field

[0001] The present invention relates to the technical field of all-solid-state lithium batteries, and in particular to a solid electrolyte and an all-solid-state lithium battery prepared using the same. Background Art

[0002] Traditional liquid lithium batteries use liquid electrolytes. Although they have the advantages of high energy density and long cycle life, they have safety hazards, such as flammability and explosion. Under extreme conditions, such as overcharging, over-discharging or high temperature, liquid electrolytes may experience thermal runaway, leading to fire or explosion. In order to solve the problems of battery leakage and post-collision combustion, it is particularly important to use solid electrolytes instead of traditional liquid electrolytes. Solid electrolytes not only improve the safety of the battery, but also have higher thermal stability and chemical corrosion resistance. At the same time, solid electrolytes can also improve the energy density and cycle life of the battery, and are suitable for a wider temperature range.

[0003] Solid electrolytes are mainly divided into two types: inorganic solid electrolytes and polymer solid electrolytes. Among them, polymer solid electrolytes are usually composed of a polymer matrix combined with lithium salts, which can flexibly fill the internal space of the battery. However, polymer solid electrolytes can still cause fires after encountering short circuits and mechanical shocks. In addition, the ionic conductivity of polymer electrolytes is relatively low, which limits the charge and discharge rate and energy density of the battery.

[0004] Therefore, we propose a solid electrolyte and an all-solid-state lithium battery prepared using the same. Summary of the invention

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

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a solid electrolyte comprises the following steps: Step S1: uniformly mix the dihalogen compound and tetrahydrofuran, add ethylene glycol and triethylamine in an ice bath, raise the temperature to 25-35° C., continue the reaction for 4-6 hours, filter, wash and dry to obtain a modified diol; Step S2: uniformly mix the polycarbonate diol and the modified diol, add isophorone diisocyanate and dibutyltin dilaurate under nitrogen protection, mix uniformly, react at 90-100° C. for 2-5 hours, add dimethylolpropionic acid, flame retardant and organic solvent, react at 70-80° C. for 4-7 hours, cool to 40-50° C., add pentaerythritol tetrakis-3-mercaptopropionate and photoinitiator, react under ultraviolet light irradiation for 1-2 hours, add triethylamine for neutralization reaction, add deionized water for emulsification, remove the organic solvent under reduced pressure, and obtain an aqueous polyurethane solution; Step S3: Evenly mix the aqueous polyurethane solution and the lithium salt, and dry them to obtain a solid electrolyte.

[0007] 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.

[0008] 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 tetrakis-3-mercaptopropionate, 1-3 parts of photoinitiator, 3-5 parts of triethylamine, and 150-250 parts of deionized water.

[0009] 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.

[0010] Further, the preparation method of the dihalogen compound is as follows: Under nitrogen protection, phosphorus oxychloride and tetrahydrofuran are mixed evenly, 2,4-diamino-6-vinyl-S-triazine and triethylamine are added, and the mixture is reacted for 2-3 hours in an ice bath, and the temperature is raised to 25-35°C, and the reaction is continued for 4-6 hours. After filtering, washing and drying, a dihalogen compound is obtained.

[0011] Furthermore, the mass ratio of the phosphorus oxychloride to tetrahydrofuran, 2,4-diamino-6-vinyl-S-triazine and triethylamine is 1:(4-6):(0.7-0.8):(0.8-1.2).

[0012] Furthermore, the preparation method of the flame retardant is as follows: Step (1): uniformly mix the dihalogen compound and tetrahydrofuran, add 2-aminobenzothiazole and triethylamine, react for 2-3 hours in an ice bath, heat to 25-35°C, continue to react for 4-6 hours, filter, wash and dry to obtain an intermediate; Step (2): heating the dihydroxy-terminated polysiloxane to 80-100° C., adding 4-hydroxyphenylboric acid and mixing evenly, and performing vacuum reaction under vacuum conditions to obtain boron-containing organosilicon; Step (3): the intermediate and tetrahydrofuran are mixed evenly, boron-containing organosilicon and triethylamine are added, the reaction is carried out in an ice bath for 2-3 hours, the temperature is raised to 25-35°C, the reaction is continued for 4-6 hours, and a flame retardant is obtained after filtering, washing and drying.

[0013] Furthermore, in the 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).

[0014] Furthermore, in the step (2), the mass ratio of the dihydroxy-terminated polysiloxane to 4-hydroxyphenylboric acid is 1:(0.1-0.3).

[0015] Furthermore, in step (2), the process conditions of the vacuum reaction are: vacuum degree 0.06-0.08 MPa, reaction temperature 130-150° C., and reaction time 8-12 h.

[0016] Furthermore, in the step (3), the mass ratio of the intermediate, tetrahydrofuran, boron-containing organosilicon and triethylamine is 1:(4-6):(1-2):(0.8-1.2).

[0017] In the above technical scheme, by controlling the dihalogen compound to be slightly excessive, one -Cl in the dihalogen compound reacts with the amino group in 2-aminobenzothiazole, introducing the thiazole structure to obtain an intermediate; then 4-hydroxyphenylboric acid reacts with the dihydroxy-terminated polysiloxane to obtain boron-containing organosilicon; finally, the remaining one -Cl in the intermediate reacts with the hydroxyl group of the boron-containing organosilicon, and triethylamine removes the hydrogen chloride generated by the reaction to obtain a flame retardant containing N, S, P, Si, and B elements.

[0018] Furthermore, in step S2, the organic solvent is acetone, and its usage is 3-5 times of the flame retardant.

[0019] Furthermore, the process conditions of the ultraviolet irradiation are: irradiation wavelength 360-400nm, irradiation intensity 20-35mW / cm 2 .

[0020] Furthermore, the lithium salt is one or more of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), lithium perchlorate or lithium hexafluorophosphate.

[0021] Furthermore, in step S3, the drying process includes: drying at 60-100° C. for 20-30 hours under vacuum conditions.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. A solid electrolyte and an all-solid-state lithium battery prepared by the present invention, by controlling the reaction of a -Cl in phosphorus oxychloride and an amino group in 2,4-diamino-6-vinyl-S-triazine, amino, vinyl and triazine structures are introduced to obtain a dihalogen compound, the triazine ring contains nitrogen atoms, which can provide additional electron cloud density, may enhance the interaction between lithium ions and the solid electrolyte, and promote ion transmission; then a condensation reaction occurs with ethylene glycol to obtain a modified diol, which can participate in the preparation process of polyurethane, giving the solid electrolyte excellent mechanical properties and high temperature resistance, and can maintain stable dimensional stability at high temperatures, ensuring the safety of lithium ion batteries working in high temperature environments.

[0023] 2. A solid electrolyte and an all-solid-state lithium battery prepared by the present invention utilizes a -Cl in a dihalogen compound to react with an amino group in 2-aminobenzothiazole to introduce a thiazole structure, which has good ionic conductivity and can improve the mobility of ions in the electrolyte, thereby enhancing its overall conductivity; the remaining -Cl in the intermediate is then reacted with boron-containing organosilicon to obtain a flame retardant containing N, S, P, Si, and B elements. Through the synergistic effect of multiple elements, the thermal stability and flame retardancy of the electrolyte can be significantly improved, and the risk of fire under high temperature or out-of-control conditions can be effectively reduced; at the same time, the flame retardant contains a siloxane segment, and the introduction of this structure enables the electrolyte to be uniformly polymerized and improves Li + Transmission, which helps to improve the cycle performance and energy density of all-solid-state lithium batteries under high current density conditions.

[0024] 3. A solid electrolyte and an all-solid-state lithium battery prepared by the present invention, by introducing pentaerythritol tetrakis-3-mercaptopropionate, can undergo a thiol-ene click reaction with double bonds in modified diols and flame retardants under ultraviolet light 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 DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In this embodiment, the polycarbonate diol: the product number is lnb-1163, which is sourced from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.; the lithium salt: lithium trifluoromethanesulfonate, CAS number is 33454-82-9; the dihydroxy-terminated polysiloxane, the product number is C303003, which is sourced from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0027] In the following examples and comparative examples, 1 part is equal to 10 g.

[0028] Embodiment 1: A method for preparing a solid electrolyte, comprising the following process: Step S1: 15 parts of a dihalogen compound and 40 parts of tetrahydrofuran are uniformly mixed, 6 parts of ethylene glycol and 25 parts of triethylamine are added under ice bath conditions, the temperature is raised to 25° C., the reaction is continued for 4 hours, and after filtering, washing and drying, a modified diol is obtained; Step S2: 40 parts of polycarbonate diol and 10 parts of modified diol were mixed evenly, and under nitrogen protection, 60 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were added and mixed evenly, and reacted at 90°C for 2h, 2 parts of dimethylolpropionic acid, 5 parts of flame retardant and 15 parts of acetone were added, and reacted at 70°C for 4h, cooled to 40°C, 20 parts of pentaerythritol tetra-3-mercaptopropionate and 1 part of photoinitiator were added, and ultraviolet light was irradiated for 1h (irradiation wavelength 360nm, irradiation intensity 20mW / cm 2 ), add 3 parts of triethylamine for neutralization reaction, then add 150 parts of deionized water for emulsification, remove acetone under reduced pressure to obtain an aqueous polyurethane solution; Step S3: 70 parts of aqueous polyurethane solution and 10 parts of lithium salt are mixed evenly, and dried at 60° C. for 20 hours under vacuum conditions to obtain a solid electrolyte; The preparation method of the dihalogen compound is as follows: Under nitrogen protection, 20 parts of phosphorus oxychloride and 80 parts of tetrahydrofuran were mixed evenly, 14 parts of 2,4-diamino-6-vinyl-S-triazine and 16 parts of triethylamine were added, and the mixture was reacted for 2 hours under ice bath conditions, and the temperature was raised to 25°C, and the reaction was continued for 4 hours. After filtering, washing and drying, a dihalogen compound was obtained; The preparation method of the flame retardant is as follows: Step (1): 5 parts of a dihalogen compound and 20 parts of tetrahydrofuran are mixed evenly, 2.25 parts of 2-aminobenzothiazole and 4 parts of triethylamine are added, the mixture is reacted in an ice bath for 2 hours, the temperature is raised to 25°C, the reaction is continued for 4 hours, and the intermediate is obtained after filtering, washing and drying; Step (2): heat 5 parts of dihydroxy-terminated polysiloxane to 80°C, add 0.5 parts of 4-hydroxyphenylboric acid and mix well, and carry out vacuum reaction under vacuum conditions (vacuum degree 0.06 MPa, reaction temperature 130°C, reaction time 8 hours) to obtain boron-containing organosilicon; Step (3): 5 parts of the intermediate and 20 parts of tetrahydrofuran are mixed evenly, 5 parts of boron-containing organosilicon and 4 parts of triethylamine are added, and the mixture is reacted for 2 hours in an ice bath, and the temperature is raised to 25°C, and the reaction is continued for 4 hours. After filtering, washing and drying, a flame retardant is obtained.

[0029] Embodiment 2: A method for preparing a solid electrolyte, comprising the following process: Step S1: 18 parts of a dihalogen compound and 50 parts of tetrahydrofuran are uniformly mixed, 10 parts of ethylene glycol and 28 parts of triethylamine are added under ice bath conditions, the temperature is raised to 30° C., the reaction is continued for 5 hours, and after filtering, washing and drying, a modified diol is obtained; Step S2: 45 parts of polycarbonate diol and 15 parts of modified diol were mixed evenly, and under nitrogen protection, 70 parts of isophorone diisocyanate and 2 parts of dibutyltin dilaurate were added and mixed evenly, and reacted at 95°C for 4 hours, 3 parts of dimethylolpropionic acid, 10 parts of flame retardant and 40 parts of acetone were added, and reacted at 75°C for 5 hours, cooled to 45°C, 30 parts of pentaerythritol tetra-3-mercaptopropionate and 2 parts of photoinitiator were added, and ultraviolet light was irradiated for 1.5 hours (irradiation wavelength 380nm, irradiation intensity 30mW / cm 2 ), add 4 parts of triethylamine for neutralization reaction, then add 200 parts of deionized water for emulsification, remove acetone under reduced pressure to obtain an aqueous polyurethane solution; Step S3: 80 parts of aqueous polyurethane solution and 20 parts of lithium salt are mixed evenly, and dried at 80° C. for 25 hours under vacuum conditions to obtain a solid electrolyte; The preparation method of the dihalogen compound is as follows: Under nitrogen protection, 30 parts of phosphorus oxychloride and 150 parts of tetrahydrofuran were mixed evenly, 22.5 parts of 2,4-diamino-6-vinyl-S-triazine and 30 parts of triethylamine were added, and the mixture was reacted for 2.5 hours in an ice bath, and the temperature was raised to 30°C, and the reaction was continued for 5 hours. After filtering, washing and drying, a dihalogen compound was obtained; The preparation method of the flame retardant is as follows: Step (1): 10 parts of a dihalogen compound and 50 parts of tetrahydrofuran are mixed evenly, 5 parts of 2-aminobenzothiazole and 10 parts of triethylamine are added, the mixture is reacted in an ice bath for 2.5 hours, the temperature is raised to 30°C, the reaction is continued for 5 hours, and the intermediate is obtained after filtering, washing and drying; Step (2): heat 15 parts of dihydroxy-terminated polysiloxane to 90°C, add 3 parts of 4-hydroxyphenylboric acid and mix well, and carry out vacuum reaction under vacuum conditions (vacuum degree 0.07 MPa, reaction temperature 140°C, reaction time 10 h) to obtain boron-containing organosilicon; Step (3): 10 parts of the intermediate and 50 parts of tetrahydrofuran are mixed evenly, 15 parts of boron-containing organosilicon and 10 parts of triethylamine are added, and the mixture is reacted in an ice bath for 2.5 hours, and the temperature is raised to 30°C, and the reaction is continued for 5 hours. After filtering, washing and drying, a flame retardant is obtained.

[0030] Embodiment 3: A method for preparing a solid electrolyte, comprising the following process: Step S1: 20 parts of a dihalogen compound and 60 parts of tetrahydrofuran are mixed evenly, 12 parts of ethylene glycol and 30 parts of triethylamine are added under ice bath conditions, the temperature is raised to 35° C., the reaction is continued for 6 hours, and after filtering, washing and drying, a modified diol is obtained; Step S2: 50 parts of polycarbonate diol and 20 parts of modified diol were mixed evenly, and under nitrogen protection, 80 parts of isophorone diisocyanate and 3 parts of dibutyltin dilaurate were added and mixed evenly, and reacted at 100°C for 5 hours, 5 parts of dimethylolpropionic acid, 15 parts of flame retardant and 75 parts of acetone were added, and reacted at 80°C for 7 hours, cooled to 40-50°C, 40 parts of pentaerythritol tetra-3-mercaptopropionate and 3 parts of photoinitiator were added, and ultraviolet light was irradiated for 2 hours (irradiation wavelength 400nm, irradiation intensity 35mW / cm 2 ), add 5 parts of triethylamine for neutralization reaction, then add 250 parts of deionized water for emulsification, remove the organic solvent under reduced pressure to obtain an aqueous polyurethane solution; Step S3: 90 parts of aqueous polyurethane solution and 30 parts of lithium salt are mixed evenly, and dried at 100° C. for 30 hours under vacuum conditions to obtain a solid electrolyte; The preparation method of the dihalogen compound is as follows: Under nitrogen protection, 40 parts of phosphorus oxychloride and 240 parts of tetrahydrofuran were mixed evenly, 32 parts of 2,4-diamino-6-vinyl-S-triazine and 48 parts of triethylamine were added, and the mixture was reacted for 3 hours under ice bath conditions, and the temperature was raised to 35°C, and the reaction was continued for 6 hours. After filtering, washing and drying, a dihalogen compound was obtained; The preparation method of the flame retardant is as follows: Step (1): 15 parts of a dihalogen compound and 90 parts of tetrahydrofuran are uniformly mixed, 8.25 parts of 2-aminobenzothiazole and 18 parts of triethylamine are added, the mixture is reacted in an ice bath for 3 hours, the temperature is raised to 35°C, the reaction is continued for 6 hours, and the intermediate is obtained after filtering, washing and drying; Step (2): 30 parts of dihydroxy-terminated polysiloxane are heated to 100° C., 9 parts of 4-hydroxyphenylboric acid are added and mixed evenly, and vacuum reaction is carried out under vacuum conditions (vacuum degree 0.08 MPa, reaction temperature 150° C., reaction time 12 h) to obtain boron-containing organosilicon; Step (3): 15 parts of the intermediate and 90 parts of tetrahydrofuran are mixed evenly, 30 parts of boron-containing organosilicon and 18 parts of triethylamine are added, and the mixture is reacted for 3 hours in an ice bath, and the mixture is heated to 35° C. and the reaction is continued for 6 hours. After filtering, washing and drying, a flame retardant is obtained.

[0031] Comparative Example 1: A method for preparing a solid electrolyte, comprising the following process: Step S1: 18 parts of a dihalogen compound and 50 parts of tetrahydrofuran are uniformly mixed, 10 parts of ethylene glycol and 28 parts of triethylamine are added under ice bath conditions, the temperature is raised to 30° C., the reaction is continued for 5 hours, and after filtering, washing and drying, a modified diol is obtained; Step S2: 45 parts of polycarbonate diol and 15 parts of modified diol were mixed evenly, and under nitrogen protection, 70 parts of isophorone diisocyanate and 2 parts of dibutyltin dilaurate were added and mixed evenly, and reacted at 95°C for 4 hours, 3 parts of dimethylolpropionic acid and 40 parts of acetone were added, and reacted at 75°C for 5 hours, cooled to 45°C, 30 parts of pentaerythritol tetra-3-mercaptopropionate and 2 parts of photoinitiator were added, and ultraviolet light was irradiated for 1.5 hours (irradiation wavelength 380nm, irradiation intensity 30mW / cm 2 ), add 4 parts of triethylamine for neutralization reaction, then add 200 parts of deionized water for emulsification, remove acetone under reduced pressure to obtain an aqueous polyurethane solution; Step S3: 80 parts of aqueous polyurethane solution and 20 parts of lithium salt are mixed evenly, and dried at 80° C. for 25 hours under vacuum conditions to obtain a solid electrolyte; Compared with Example 2, no flame retardant was added in Comparative Example 1, and other steps were the same as those in Example 2.

[0032] Comparative Example 2: A method for preparing a solid electrolyte, comprising the following process: Step S1: 45 parts of polycarbonate diol and 15 parts of ethylene glycol were mixed evenly, and under nitrogen protection, 70 parts of isophorone diisocyanate and 2 parts of dibutyltin dilaurate were added and mixed evenly, and reacted at 95°C for 4 hours, 3 parts of dimethylolpropionic acid, 10 parts of flame retardant and 40 parts of acetone were added, and reacted at 75°C for 5 hours, cooled to 45°C, 30 parts of pentaerythritol tetra-3-mercaptopropionate and 2 parts of photoinitiator were added, and ultraviolet light was irradiated for 1.5 hours (irradiation wavelength 380nm, irradiation intensity 30mW / cm 2 ), add 4 parts of triethylamine for neutralization reaction, then add 200 parts of deionized water for emulsification, remove acetone under reduced pressure to obtain an aqueous polyurethane solution; Step S2: 80 parts of aqueous polyurethane solution and 20 parts of lithium salt are mixed evenly, and dried at 80° C. for 25 hours under vacuum conditions to obtain a solid electrolyte; Compared with Example 2, the modified diol in Comparative Example 2 is replaced with ethylene glycol of the same mass, and the other steps are the same as those in Example 2.

[0033] Comparative Example 3: A method for preparing a solid electrolyte, comprising the following process: Compared with Example 2, in Comparative Example 3, pentaerythritol tetrakis-3-mercaptopropionate is not added, and other steps are the same as those in Example 2.

[0034] Experiment: 1. Take the solid electrolytes obtained in Examples 1-3 and Comparative Examples 1-3, prepare samples, test their performance and record the test results: Vertical combustion test: Test according to GB / T 2408-2021 "Horizontal and vertical methods for determination of combustion performance of plastics"; Ionic conductivity test: Use an electrochemical workstation to perform solid electrolyte electrochemical impedance spectroscopy (EIS) test, the test frequency range is 1.0×10 -2 -1.0×10 5 Hz, amplitude 7mV, measurement temperature range 25-100℃; then use the formula σ=L / (R×S) to calculate the conductivity, 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.

[0035] 2. Lithium iron phosphate (LFP) was used 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 were assembled into 2032-type button batteries, which were cycled 100 times at a rate of 1C to test the capacity retention rate. The voltage range was 2.8-4.5V.

[0036] The test results are as follows:

[0037] According to the data in the above table, we can clearly draw the following conclusions: Compared with Examples 1-3, the flame retardancy, ionic conductivity and capacity retention rate of the product obtained in Comparative Example 1 are all reduced, which shows that the flame retardant prepared by the present invention can effectively improve the safety and performance of the battery.

[0038] Compared with Examples 1-3, the ionic conductivity and capacity retention rate of the products obtained in Comparative Examples 2 and 3 are both reduced, indicating that the modified diol prepared by the present invention improves the intermolecular interaction by introducing polar groups (such as amino and vinyl) and triazine structures, thereby improving the conductivity of lithium ions; at the same time, the present invention increases the crosslinking density and optimizes the ion migration channel by adding pentaerythritol tetrakis-3-mercaptopropionate, thereby enhancing the overall performance of the solid electrolyte.

[0039] 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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a solid electrolyte, characterized in that: The steps include: Step S1: uniformly mix the dihalogen compound and tetrahydrofuran, add ethylene glycol and triethylamine in an ice bath, raise the temperature to 25-35° C., continue the reaction for 4-6 hours, filter, wash and dry to obtain a modified diol; Step S2: uniformly mix the polycarbonate diol and the modified diol, add isophorone diisocyanate and dibutyltin dilaurate under nitrogen protection, mix uniformly, react at 90-100° C. for 2-5 hours, add dimethylolpropionic acid, flame retardant and organic solvent, react at 70-80° C. for 4-7 hours, cool to 40-50° C., add pentaerythritol tetrakis-3-mercaptopropionate and photoinitiator, react under ultraviolet light irradiation for 1-2 hours, add triethylamine for neutralization reaction, add deionized water for emulsification, remove the organic solvent under reduced pressure, and obtain an aqueous polyurethane solution; Step S3: Evenly mix the aqueous polyurethane solution and the lithium salt, and dry them to obtain a solid electrolyte.

2. The method for preparing a solid electrolyte according to claim 1, characterized in that: 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.

3. The method for preparing a solid electrolyte according to claim 2, characterized in that: 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 tetrakis-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: 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.

5. The method for preparing a solid electrolyte according to claim 4, characterized in that: The preparation method of the dihalogen compound is as follows: Under nitrogen protection, phosphorus oxychloride and tetrahydrofuran are mixed evenly, 2,4-diamino-6-vinyl-S-triazine and triethylamine are added, and the mixture is reacted for 2-3 hours in an ice bath, and the temperature is raised to 25-35°C, and the reaction is continued for 4-6 hours. After filtering, washing and drying, a dihalogen compound is obtained.

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

7. The method for preparing a solid electrolyte according to claim 3, characterized in that: The preparation method of the flame retardant is as follows: Step (1): uniformly mix the dihalogen compound and tetrahydrofuran, add 2-aminobenzothiazole and triethylamine, react for 2-3 hours in an ice bath, heat to 25-35°C, continue to react for 4-6 hours, filter, wash and dry to obtain an intermediate; Step (2): heating the dihydroxy-terminated polysiloxane to 80-100° C., adding 4-hydroxyphenylboric acid and mixing evenly, and performing vacuum reaction under vacuum conditions to obtain boron-containing organosilicon; Step (3): the intermediate and tetrahydrofuran are mixed evenly, boron-containing organosilicon and triethylamine are added, the reaction is carried out in an ice bath for 2-3 hours, the temperature is raised to 25-35°C, the reaction is continued for 4-6 hours, and a flame retardant is obtained after filtering, washing and drying.

8. The solid electrolyte and the all-solid-state lithium battery prepared therefrom according to claim 7, characterized in that: In the step (3), the mass ratio of the intermediate, tetrahydrofuran, boron-containing organosilicon and triethylamine is 1:(4-6):(1-2):(0.8-1.2).

9. The solid electrolyte and the all-solid-state lithium battery prepared therefrom according to claim 2, 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.

10. 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 to 9.

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