Flame-retardant polyurethane acrylate solid electrolyte membrane, preparation method and application thereof
By preparing a flame-retardant polyurethane acrylate solid electrolyte membrane, and utilizing the synergistic effect of multiple elements such as phosphonate diol and halloysite nano-silicon aluminum tubes, the problems of flammability and contamination in the preparation process of all-solid polymer electrolytes were solved, thus achieving a high-safety and high-performance lithium battery electrolyte membrane.
Patent Information
- Application Number
- CN202310186988.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-27
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2043-02-27
AI Technical Summary
Existing all-solid polymer electrolyte materials are flammable, and their manufacturing processes cause significant pollution. They also have low room-temperature ionic conductivity, making it difficult to meet the safety and performance requirements of flexible lithium batteries.
Flame-retardant polyurethane acrylate solid electrolyte membranes were prepared by using phosphonate diols and halloysite nano-silicon aluminum tubes as raw materials through polymerization and UV curing. Combined with lithium salts and photoinitiators, a multi-element synergistic flame-retardant mechanism was formed, which improved the lithium-ion transport channel.
It improves the limiting oxygen index and room temperature ionic conductivity of the electrolyte membrane, reduces heat release and smoke during combustion, reduces environmental pollution and energy loss, and enhances the safety and performance of lithium batteries.
Smart Images
Figure CN116207344B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium batteries, in particular to a flame-retardant polyurethane acrylate solid electrolyte membrane and a preparation method and application thereof. BACKGROUND
[0002] The imminent energy crisis and the increasingly serious environmental problems have greatly promoted the development of new energy industry. Lithium batteries as important energy storage devices have received more and more attention. With the gradual entry of wearable and foldable electronic devices into millions of households, higher requirements are put forward for the flexibility and safety of lithium batteries. Due to the inherent defects such as flammability, volatility and leakage of electrolyte, and penetration of lithium dendrites through the electrolyte separator, traditional liquid lithium batteries may be gradually replaced by all-solid-state batteries in the future.
[0003] Although the inorganic solid-state electrolyte has a high ionic conductivity, it is brittle and not resistant to bending, which is difficult to meet the development needs of flexible batteries. Therefore, all-solid-state polymer electrolytes based on polymers and copolymers have become an important research direction for electrolyte materials for flexible batteries.
[0004] Most of the reported all-solid-state polymer electrolytes are flammable, such as polyethylene oxide and polyurethane. Once a fire is caused by thermal runaway in the assembled battery, a large amount of heat and smoke will be released, which can cause death of humans and animals in a short time. Moreover, most solid-state polymer electrolytes are prepared by solution casting and thermal curing methods. The volatilization of organic solvents and the continuous high-temperature thermal curing for several hours or even several tens of hours in the preparation process inevitably cause environmental pollution and excessive energy consumption. In addition, the low room temperature ionic conductivity of most solid-state polymer electrolytes is still a problem that cannot be ignored. SUMMARY
[0005] Therefore, the present application provides a flame-retardant polyurethane acrylate solid electrolyte membrane and a preparation method and application thereof. The prepared solid electrolyte membrane has a high limiting oxygen index and a high room temperature ionic conductivity, and the production process is environmentally friendly and energy-saving.
[0006] To achieve the above technical purposes, the present application adopts the following technical solutions:
[0007] In a first aspect, the present application provides a preparation method of a flame-retardant polyurethane acrylate solid electrolyte membrane, comprising the following steps:
[0008] S1. Under the conditions of inert atmosphere and catalyst, a polyurethane acrylate prepolymer is obtained by polymerization reaction using phosphonate diol, diisocyanate and hydroxyalkyl acrylate as raw materials;
[0009] S2. mixing the polyurethane acrylate prepolymer, lithium salt, halloysite nanosilicon aluminum tube, photoinitiator and reactive diluent to obtain a coating solution, and then the coating solution is pushed flat to form a film, and the film is cured by ultraviolet light to obtain the flame-retardant polyurethane acrylate solid electrolyte film.
[0010] Preferably, before step S2, the halloysite nanosilicon aluminum tube is further subjected to acid corrosion.
[0011] Preferably, the molecular structure of the phosphonate diol is shown in Formula I:
[0012] Formula I, wherein R1 and R2 are selected from any one of ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, isooctyl, 1-decyl, cyclohexyl, cyclopentyl, cycloheptyl and phenyl.
[0013] Preferably, the preparation method of the phosphonate diol comprises the following steps:
[0014] K1. Under an inert atmosphere, ring phosphoric anhydride and dihydric alcohol / diphenol are used as raw materials to perform ring-opening alcoholysis reaction to obtain methyl propionic acid ester phosphinic acid;
[0015] K2. Under an inert atmosphere and in the presence of a catalyst, methyl propionic acid ester phosphinic acid and dihydric alcohol / diphenol are used as raw materials to perform esterification reaction to obtain phosphonate diol.
[0016] Preferably, the molar ratio of the phosphonate diol, diisocyanate and hydroxyalkyl acrylate is 1:(2-2.2):(2-2.2).
[0017] Preferably, the lithium salt is one or more of lithium bistrifluoromethanesulfonimide, lithium perchlorate, lithium bistrifluorosulfonimide, lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bisoxalate borate.
[0018] Preferably, the catalyst is a mixture of dibutyltin dilaurate and stannous octoate.
[0019] Preferably, the reactive diluent includes one or more of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl dipropyl acrylate (HPHPDA), isobornyl isobornyl ibuprofenate (IBOA), ethoxy ethoxy ethyl acrylate (EOEOEA) and 1,6-hexanedioic acid diacrylate (HDDA).
[0020] In a second aspect, the present application provides a flame-retardant polyurethane acrylate solid electrolyte film.
[0021] In a third aspect, the present application provides a flame-retardant polyurethane acrylate solid electrolyte film for use in the field of lithium batteries.
[0022] The beneficial effects of the present application are as follows:
[0023] The flame-retardant polyurethane acrylate solid electrolyte membrane prepared by the present application using phosphonate diol and halloysite nanometer silicon aluminum tube as raw materials has high limiting oxygen index and low heat release and smoke release, realizes good P-N-Al-Si multi-element synergistic flame-retardant mechanism, and greatly improves the safety performance of the electrolyte;
[0024] The flame-retardant polyurethane acrylate solid electrolyte prepared by the present application using acid corrosion treated halloysite nanometer silicon aluminum tube has more Si-OH exposed on the outer surface of halloysite, which can combine with more Li+, thereby promoting the dissociation of lithium salt, and also inhibiting the crystallization of polymer, improving the lithium ion transmission channel, and thereby improving the ionic conductivity of the electrolyte membrane at room temperature;
[0025] The flame-retardant polyurethane acrylate solid electrolyte membrane prepared by the present application using ultraviolet light curing process avoids the environmental pollution caused by the volatilization of organic solvents in the traditional solution casting method and the excessive energy loss problem in the thermal curing method, and meets the environmental protection requirements of energy saving and emission reduction. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 The infrared spectrum of the flame-retardant polyurethane acrylate prepared for Example 1. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.
[0028] The present application provides a preparation method of a flame-retardant polyurethane acrylate solid electrolyte membrane, comprising the following steps:
[0029] S1. Under the conditions of inert atmosphere and catalyst, polymeric reaction is carried out using phosphonate diol, diisocyanate and hydroxyalkyl acrylate as raw materials to obtain a polyurethane acrylate prepolymer;
[0030] S2. The polyurethane acrylate prepolymer, lithium salt, halloysite nanometer silicon aluminum tube, photoinitiator and active diluent are mixed to obtain a coating solution, the coating solution is pushed flat on a clean tetrafluoroethylene plate by using a coating device with different thicknesses, and then ultraviolet light curing is performed, thereby obtaining a flame-retardant polyurethane acrylate solid electrolyte membrane.
[0031] In some embodiments, the molar ratio of phosphonate diol, diisocyanate and hydroxyalkyl acrylate in step S1 is 1:(2-2.2):(2-2.2); and the catalyst in step S1 is a mixture of dibutyltin dilaurate and stannous octoate.
[0032] In some embodiments, in step S2, the lithium salt is one or more of lithium bistrifluoromethanesulfonimide, lithium perchlorate, lithium bisfluorosulfonimide, lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bisoxalate borate; the active diluent in step S2 includes one or more of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl diacrylate (HPHPDA), isobornyl isobornate (IBOA), ethoxyethoxyethyl acrylate (EOEOEA) and 1,6-hexanediol diacrylate (HDDA); the hydroxyalkyl acrylate in step S2 includes one or more of hydroxyethyl acrylate, 4-hydroxybutyl acrylate and 4-hydroxycyclohexyl acrylate; and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173).
[0033] Specifically, in step S1, the polyurethane acrylate prepolymer is prepared by the following method:
[0034] S11. Under an inert atmosphere, a heating reaction is performed on phosphonate diol and diisocyanate to obtain an intermediate;
[0035] S12. Under the action of a catalyst, a heating reaction is performed on the intermediate and hydroxyalkyl acrylate to obtain the polyurethane acrylate prepolymer.
[0036] In some embodiments, in step S11, the inert atmosphere is nitrogen, and in step S12, the catalyst is a mixture of dibutyltin dilaurate and stannous octoate; the heating temperature in steps S11 and S12 is 70-90°C.
[0037] The reaction equation of the polyurethane acrylate prepolymer is as follows:
[0038]
[0039]
[0040] wherein,
[0041] In the scheme, the halloysite nanosilicon aluminum tube has a hollow tubular structure with both ends open and not sealed, and its chemical composition is Al2Si2O5(OH)4. In some embodiments, before step S2, the halloysite nanosilicon aluminum tube is further subjected to acid corrosion, and the acid used is one or a mixture of several of sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid.
[0042] In the scheme, the molecular structure of the phosphonate diol is shown in formula I:
[0043] wherein R1 and R2 are each selected from any one of ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, isooctyl, 1-decyl, cyclohexyl, cyclopentyl, cycloheptyl and phenyl.
[0044] A method for preparing a phosphonate diol, comprising the following steps:
[0045] K1. Under an inert atmosphere, a ring phosphonic anhydride and a dihydric alcohol / diphenol are used as raw materials to perform a ring-opening alcoholysis reaction to obtain a methyl propionate phosphinate; the temperature of the ring-opening alcoholysis reaction is 120-160°C, and the molar ratio of the ring phosphonic anhydride to the dihydric alcohol / diphenol is 1:1-1.2, and the reaction formula is as follows:
[0046] wherein R1 is selected from any one of ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, isooctyl, 1-decyl, cyclohexyl, cyclopentyl, cycloheptyl and phenyl.
[0047] K2. Under an inert atmosphere and a catalyst, a methyl propionate phosphinate and a dihydric alcohol / diphenol are used as raw materials to perform an esterification reaction at 150-200°C, the molar ratio of the methyl propionate phosphinate to the dihydric alcohol or the diphenol is 1:1-1.2, to obtain a phosphonate diol, and the reaction formula is as follows:
[0048] wherein R2 is selected from any one of ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, isooctyl, 1-decyl, cyclohexyl, cyclopentyl, cycloheptyl and phenyl, and in some embodiments, the catalyst in K2 is a 4A molecular sieve.
[0049] The application provides a flame-retardant polyurethane acrylate solid-state electrolyte film.
[0050] The application provides application of the flame-retardant polyurethane acrylate solid-state electrolyte film in the field of lithium batteries.
[0051] Raw material preparation
[0052] The phosphonate diol used in the embodiments of the present scheme is methyl propionate glycol phosphonate glycol or methyl propionate glycol phosphonate butanediol.
[0053] The preparation method of the methyl propionate glycol phosphonate glycol is as follows:
[0054] Put 1.0 mol of cyclic phosphoric anhydride and 1.0 mol of ethylene glycol in a three-necked flask, mechanically stir the reaction at 120°C for 3h, after stirring is completed, stand and cool to room temperature to obtain a bright yellow clear liquid, which is ethylene glycol methylpropionate phosphinic acid, the above operations are carried out under nitrogen atmosphere;
[0055] The structural formula of the cyclic phosphoric anhydride is:
[0056]
[0057] Put 1.0 mol of ethylene glycol methylpropionate phosphinic acid, 1.03 mol of ethylene glycol and 100g of 4A molecular sieve in a three-necked flask, mechanically stir the reaction at 150°C for 4h, then filter hot, stand and cool the filtrate to room temperature to obtain a brownish yellow gummy solid, which is ethylene glycol methylpropionate phosphonic acid ethylene glycol ester flame retardant, the above operations are carried out under nitrogen atmosphere.
[0058] The preparation method of ethylene glycol methylpropionate phosphonic acid butylene glycol ester is basically the same as that of ethylene glycol methylpropionate phosphonic acid ethylene glycol ester, except that 1,4-butanediol is used instead of butanediol in the raw materials.
[0059] The present scheme is further illustrated by specific examples as follows.
[0060] Example 1
[0061] A flame-retardant polyurethane acrylate solid-state electrolyte film is prepared by the following method:
[0062] S1. Put 5.0g of ethylene glycol methylpropionate phosphonic acid ethylene glycol ester and 9.43g of hexamethylene diisocyanate, which have been vacuum dehydrated and dried, into a three-necked flask, stir the reaction at 80°C for 3h under nitrogen atmosphere, then add 5.92g of dried hydroxyethyl acrylate and 3 drops of each of dibutylene lauric acid and stannous octoate to the system, continue to stir the reaction at 80°C for 2h to obtain a flame-retardant polyurethane acrylate prepolymer;
[0063] S2. Add 6.11g of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl acrylate, 4.07g of lithium bistrifluoromethanesulfonimide, 1.02g of halloysite nanosilicon aluminum tube (soaked in 2mol / L sulfuric acid for 7 days) and 0.61g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173) to the flame-retardant polyurethane acrylate prepolymer obtained above, and fully stir and mix to form a coating solution, push the coating solution onto a clean tetrafluoroethylene plate with a 100μm-thick coating applicator to form a film, and then place it under a UV lamp for curing for 30s to obtain a flame-retardant polyurethane acrylate solid-state electrolyte film with a thickness of 89μm.
[0064] Combination Figure 1 , the peak a (3548 cm -1 ) is the stretching vibration peak of Si-OH on the surface of halloysite nanosilicon aluminum tube in the flame-retardant polyurethane acrylate solid-state electrolyte, the peak b (3349 cm -1 ) belongs to the -NH peak in the polyurethane acrylate structure, the peak c (2931 cm -1 ) and the peak d (2861 cm -1 ) correspond to the asymmetric and symmetric stretching vibration peaks of -CH2- respectively, the peak e (1712 cm -1 ) is the characteristic peak of ester group (C=O), the peak f (1502 cm -1 ) corresponds to the absorption peak of P-O-CH2, the peak g (1477 cm -1 ) is the deformation peak of -CH2-, the peak h (1332 cm -1 ) is consistent with the absorption peak of -C-SO2-N in the lithium salt, the peak i (1256 cm -1 ) is consistent with the absorption peak of P-CH3, the peak j (1127 cm -1 ) is the characteristic peak of Si-O-Si bond, the peak k (1069 cm -1 ) belongs to P=O, the peak l (1046 cm -1 ) belongs to -S-N-S-, the peak m (983 cm -1 ) and the peak n (916 cm -1 ) belong to the stretching vibration peaks of P-O and Al-OH respectively, the above analysis proves that the flame-retardant polyurethane acrylate solid-state electrolyte film has been successfully prepared.
[0065] Example 2
[0066] A flame-retardant polyurethane acrylate solid-state electrolyte film is prepared by the following method:
[0067] S1. After vacuum dewatering and drying treatment, 5.0 g of ethylene glycol methylpropionate phosphonate ethylene glycol ester and 9.43 g of hexamethylene diisocyanate are added to a three-necked flask and stirred at 80°C for 3h under nitrogen atmosphere, then 5.92 g of dried hydroxyethyl acrylate and 3 drops of each of dibutyl lauric acid dibutylene and stannous octoate are added, and the stirring reaction is continued at 80°C for 2h to obtain a flame-retardant polyurethane acrylate prepolymer;
[0068] S2. Add 6.11g of 1,6-adipic acid diacrylate, 4.07g of lithium bis(trifluoromethanesulfonyl)imide, 1.02g of halloysite nano-silica aluminum tube (soaked in 2mol / L sulfuric acid for 7 days) and 0.61g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure1173) to the flame-retardant polyurethane acrylate prepolymer obtained above and stir thoroughly to form a coating solution. Apply the coating solution to a clean tetrafluoroethylene plate using a 100μm thickness coating applicator to form a film, and then cure it under a UV lamp for 30s to obtain a flame-retardant polyurethane acrylate solid electrolyte membrane with a thickness of 82μm.
[0069] Example 3
[0070] A flame-retardant polyurethane acrylate solid electrolyte membrane, the preparation method of which is as follows:
[0071] S1. Add 5.0g of ethylene glycol methyl methacrylate and ethylene glycol phosphonate, which have been vacuum dehydrated and dried, and 9.43g of hexamethylene diisocyanate to a three-necked flask. Stir and react at 80°C for 3 hours under a nitrogen atmosphere. Then add 5.92g of dried hydroxyethyl acrylate, 3 drops each of dibutyl laurate and stannous octoate to the system. Continue stirring and reacting at 80°C for 2 hours to obtain flame-retardant polyurethane acrylate prepolymer.
[0072] S2. Add 6.11g of 1,6-adipic acid diacrylate, 4.07g of lithium perchlorate, 1.02g of halloysite nano-silica aluminum tube (soaked in 2mol / L sulfuric acid for 7 days) and 0.61g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure1173) to the flame-retardant polyurethane acrylate prepolymer obtained above and stir thoroughly to form a coating solution. Apply the coating solution to a clean tetrafluoroethylene plate using a 100μm thickness coating applicator to form a film, and then cure it under a UV lamp for 30s to obtain a flame-retardant polyurethane acrylate solid electrolyte membrane with a thickness of 86μm.
[0073] Example 4
[0074] A flame-retardant polyurethane acrylate solid electrolyte membrane, the preparation method of which is as follows:
[0075] S1. Add 5.0g of ethylene glycol methyl propionate and ethylene glycol phosphonate, which have been vacuum dehydrated and dried, and 14.05g of diphenylmethane diisocyanate to a three-necked flask. Stir and react at 80°C for 3 hours under a nitrogen atmosphere. Then add 5.92g of dried hydroxyethyl acrylate, 3 drops each of dibutyl laurate and stannous octoate to the system. Continue stirring and reacting at 80°C for 2 hours to obtain flame-retardant polyurethane acrylate prepolymer.
[0076] S2. To the above obtained flame-retardant polyurethane acrylate prepolymer, 7.49 g of 1,6-hexanediol diacrylate, 4.99 g of lithium bis-trifluoromethanesulfonimide, 1.25 g of halloysite nanosilica-aluminum tube (after 7 days of 4 mol / L hydrochloric acid immersion), and 0.75 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173) were added and fully stirred and mixed uniformly to form a coating solution, the coating solution was pushed flat into a film on a clean tetrafluoroethylene plate with a 100 μm thickness coating applicator, and then placed under a UV lamp for curing for 30 s to obtain a flame-retardant polyurethane acrylate solid electrolyte film with a thickness of 91 μm.
[0077] Example 5
[0078] A flame-retardant polyurethane acrylate solid electrolyte film was prepared by the following method:
[0079] S1. After vacuum dehydration and drying treatment, 5.0 g of methylpropionic acid glycol ester phosphonic acid glycol ester and 14.05 g of diphenylmethane diisocyanate were added to a three-necked flask and stirred at 80°C for 3 h, then 5.92 g of dried hydroxyethyl acrylate and 3 drops of each of dibutyl lauric acid and stannous octoate were added to the system, and the stirring reaction was continued at 80°C for 2 h to obtain a flame-retardant polyurethane acrylate prepolymer;
[0080] S2. To the above obtained flame-retardant polyurethane acrylate prepolymer, 7.49 g of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl diacrylate, 4.99 g of lithium cobaltate, 1.25 g of halloysite nanosilica-aluminum tube (after 7 days of 4 mol / L hydrochloric acid immersion), and 0.75 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173) were added and fully stirred and mixed uniformly to form a coating solution, the coating solution was pushed flat into a film on a clean tetrafluoroethylene plate with a 200 μm thickness coating applicator, and then placed under a UV lamp for curing for 30 s to obtain a flame-retardant polyurethane acrylate solid electrolyte film with a thickness of 166 μm.
[0081] Example 6
[0082] A flame-retardant polyurethane acrylate solid electrolyte film was prepared by the following method:
[0083] S1. After vacuum dehydration and drying treatment, 5.0 g of methylpropionic acid glycol ester phosphonic acid glycol ester and 14.05 g of diphenylmethane diisocyanate were added to a three-necked flask and stirred at 80°C for 3 h, then 5.92 g of dried hydroxyethyl acrylate and 3 drops of each of dibutyl lauric acid and stannous octoate were added to the system, and the stirring reaction was continued at 80°C for 2 h to obtain a flame-retardant polyurethane acrylate prepolymer;
[0084] S2. To the above-obtained flame-retardant polyurethane acrylate prepolymer, 7.49 g of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl acrylate, 4.99 g of lithium hexafluorophosphate, 1.25 g of halloysite nanosilicon aluminum tube (after 7 days of 2 mol / L sulfuric acid immersion), and 0.75 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173) were added and fully stirred to form a coating solution. The coating solution was pushed onto a clean tetrafluoroethylene plate with a 200 μm thick coating applicator to form a film, and then placed under a UV lamp for curing for 30 s to obtain a flame-retardant polyurethane acrylate solid electrolyte film with a thickness of 173 μm.
[0085] Example 7
[0086] A flame-retardant polyurethane acrylate solid electrolyte film was prepared by the following method:
[0087] S1. After vacuum dewatering and drying treatment, 5.0 g of ethylene glycol methylpropionate butanediol phosphonate, 10.78 g of hexamethylene diisocyanate were added to a three-necked flask and stirred at 80°C for 3 h. Then, 6.77 g of dried hydroxyethyl acrylate, 3 drops of dibutyl lauroylate, and 3 drops of stannous octoate were added to the system, and the stirring reaction was continued at 80°C for 2 h to obtain a flame-retardant polyurethane acrylate prepolymer;
[0088] S2. To the above-obtained flame-retardant polyurethane acrylate prepolymer, 9.02 g of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl acrylate, 4.51 g of lithium bistrifluoromethanesulfonimide, 1.13 g of halloysite nanosilicon aluminum tube (after 7 days of 2 mol / L sulfuric acid immersion), and 0.68 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173) were added and fully stirred to form a coating solution. The coating solution was pushed onto a clean tetrafluoroethylene plate with a 100 μm thick coating applicator to form a film, and then placed under a UV lamp for curing for 30 s to obtain a flame-retardant polyurethane acrylate solid electrolyte film with a thickness of 85 μm.
[0089] Example 8
[0090] A flame-retardant polyurethane acrylate solid electrolyte film was prepared by the following method:
[0091] S1. 5.0 g of ethylene glycol methylpropionate butanediol phosphonate, 10.78 g of hexamethylene diisocyanate were added into a three-necked flask and stirred at 80°C for 3 h under nitrogen atmosphere, then 6.77 g of dried hydroxyethyl acrylate and 3 drops of dibutyl lauroyl peroxide and stannous octoate were added into the system, and the stirring reaction was continued at 80°C for 2 h to obtain a flame-retardant polyurethane acrylate prepolymer;
[0092] S2. 9.02 g of 1,6-hexanedioic acid diacrylate, 4.51 g of lithium bistrifluoromethanesulfonimide, 1.13 g of halloysite nanosilicon aluminum tube (soaked in 2 mol / L sulfuric acid for 7 days), and 0.68 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173) were added into the flame-retardant polyurethane acrylate prepolymer obtained above and stirred to form a coating solution, which was pushed onto a clean tetrafluoroethylene plate with a 200 μm thick coating applicator to form a film, and then placed under a UV lamp for curing for 30 s to obtain a flame-retardant polyurethane acrylate solid-state electrolyte film with a thickness of 181 μm.
[0093] Comparative Example 1
[0094] A solid-state electrolyte film was prepared by the same method as in Example 1, except that the ethylene glycol methylpropionate butanediol phosphonate was replaced by ethylene glycol, and the same amount of halloysite nanosilicon aluminum tube was removed.
[0095] Comparative Example 2
[0096] A solid-state electrolyte film was prepared by the same method as in Example 1, except that only the ethylene glycol methylpropionate butanediol phosphonate was replaced by ethylene glycol, and the other components remained unchanged.
[0097] Comparative Example 3
[0098] A solid-state electrolyte film was prepared by the same method as in Example 1, except that only the same amount of halloysite nanosilicon aluminum tube was removed, and the other components remained unchanged.
[0099] Evaluation Test
[0100] The solid-state electrolyte films obtained in Examples 1-8 and Comparative Examples 1-3 were tested for performance:
[0101] Flame retardant performance test: the limiting oxygen index of the sample was tested by JF-3 type oxygen index tester of Nanjing Jiangning District Analysis Instrument Factory; the heat release of the sample during combustion was tested by MCC-2 type micro calorimeter of American Govmark company, the sample mass was 5-10 mg, the flow rates of nitrogen and oxygen were 80 ml / min and 20 ml / min respectively; the smoke density of the sample was tested by CDS-JYMD-1 type plastic smoke density experimental device, and the results are shown in Table 1.
[0102] Conductivity test: the electrochemical impedance spectroscopy (EIS) test of the sample was carried out at 20℃ by using PGSTAT302N type electrochemical workstation of Switzerland, the ionic conductivity of each electrolyte was calculated by the formula σ=L / (R*S) (σ is the ionic conductivity, L is the thickness of the electrolyte membrane, R is the bulk impedance, and S is the area of the solid electrolyte membrane), and the results are shown in Table 1.
[0103] Table 1 Performance test results
[0104]
[0105] From the data in Table 1, it can be seen that the flame-retardant polyurethane acrylate solid electrolyte membrane prepared in Examples 1-8 has good flame-retardant performance, and compared with Comparative Example 1, the limiting oxygen index (LOI) is greatly improved from 18.6% to 33.1%, and the indicators such as maximum heat release (PHRR), total heat release (THR), smoke release rate (SRR) and total smoke release (TSR) during combustion are significantly reduced, which indicates that the phosphonate diol and halloysite nanosilicon aluminum tube composite flame-retardant polyurethane acrylate solid electrolyte used in the system of the present application shows good P-N-Al-Si multi-element synergistic flame-retardant effect, which can greatly improve the safety performance of the solid-state polymer electrolyte.
[0106] In addition, the ESI test results show that compared with Comparative Example 1, the ionic conductivity of the flame-retardant polyurethane acrylate solid electrolyte membrane prepared in Examples 1-8 at room temperature (20℃) is improved by more than two orders of magnitude, which is on the one hand due to the P=O and P-O in the structure of the phosphonate diol can provide more lone pair electrons, which can enhance the solubility and complexing ability of lithium ions and improve the transmission channel of lithium ions; on the other hand, the introduction of halloysite nanosilicon aluminum tube disrupts the crystal phase structure of the polymer, reduces the crystallinity and regularity of the polymer, and the outer surface of the halloysite after acid corrosion treatment will expose more Si-OH, which can combine with more Li + ions, thereby promoting the dissociation of lithium salt, thereby achieving good synergistic flame-retardant effect while improving the room temperature ionic conductivity of the polyurethane acrylate solid electrolyte membrane.
[0107] It is not difficult to find from the comparison of the data in Comparative Example 1 with the data in Comparative Example 2 and Comparative Example 3 that the flame-retardant property and the room temperature ionic conductivity of the polyurethane acrylate are improved by using phosphonate diol alone or halloysite nanosilica-aluminum tube alone, but the effect is far less obvious than the effect of the phosphonate diol and halloysite nanosilica-aluminum tube compound system used in Examples 1-8.
[0108] It is worth mentioning that, unlike the traditional solution casting method and the thermal curing method process route, the present application uses ultraviolet curing process to prepare the flame-retardant polyurethane acrylate solid-state polymer electrolyte, which avoids the environmental pollution and excessive energy loss problems caused by the volatilization of organic solvents and long time high temperature thermal curing, and conforms to the national energy saving, emission reduction and environmental protection policy.
[0109] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which shall be covered within the protection scope of the present application.
Claims
1. A method for preparing a flame-retardant polyurethane acrylate solid-state electrolyte film, characterized by, The preparation method comprises the following steps: S1. Under the conditions of inert atmosphere and catalyst, a polyurethane acrylate prepolymer is prepared by polymerization reaction of phosphonate diol, diisocyanate and hydroxyalkyl acrylate as raw materials; S2. A coating solution is prepared by mixing the polyurethane acrylate prepolymer, lithium salt, halloysite nanosilicon aluminum tube, photoinitiator and reactive diluent, and the coating solution is flat-pushed to form a film, and then the film is cured by ultraviolet light to obtain the flame-retardant polyurethane acrylate solid electrolyte film.
2. The method for preparing the flame-retardant polyurethane acrylate solid electrolyte membrane according to claim 1, characterized in that, Before step S2, the halloysite nanosilicon aluminum tube is further subjected to acid corrosion.
3. The method for preparing the flame-retardant polyurethane acrylate solid electrolyte membrane according to claim 1, characterized in that, The molecular structure of the phosphonate diol is shown in formula I: wherein R1, R2are each selected from any one of ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, isooctyl, 1-decyl, cyclohexyl, cyclopentyl, cycloheptyl and phenyl.
4. The method for preparing the flame-retardant polyurethane acrylate solid electrolyte membrane according to claim 1, characterized in that, The preparation method of the phosphonate diol comprises the following steps: K1. Under the conditions of inert atmosphere, ring phosphoric anhydride and dihydric alcohol / diphenol are used as raw materials to perform ring-opening alcoholysis reaction to obtain methyl propionic ester hypophosphite; K2. Under the conditions of inert atmosphere and catalyst, the methyl propionic ester hypophosphite and the dihydric alcohol / diphenol are used as raw materials to perform esterification reaction to obtain the phosphonate diol.
5. The method for preparing the flame-retardant polyurethane acrylate solid electrolyte membrane according to claim 1, characterized in that, The molar ratio of the phosphonate diol, diisocyanate and hydroxyalkyl acrylate is 1:(2-2.2):(2-2.2).
6. The method for preparing the flame-retardant polyurethane acrylate solid electrolyte membrane according to claim 1, characterized in that, The lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bis(oxalato)borate.
7. The method for preparing the flame-retardant polyurethane acrylate solid electrolyte membrane according to claim 1, characterized in that, The catalyst is a mixture of dibutyltin dilaurate and stannous octoate.
8. The method for preparing the flame-retardant polyurethane acrylate solid electrolyte membrane according to claim 1, characterized in that, The reactive diluent comprises one or more of 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl acrylate (HPHPDA), isobornyl ibornate (IBOA), ethoxyethoxyethyl acrylate (EOEOEA) and 1,6-hexanediol diacrylate (HDDA).
9. A flame-retardant polyurethane acrylate solid electrolyte film prepared by the preparation method of any one of claims 1-8.
10. Application of the flame-retardant polyurethane acrylate solid electrolyte film of claim 9 in the field of lithium batteries.