Flame-retardant in-situ polymerized gel electrolyte, preparation method and application thereof

Abstract

The application provides a kind of fire-retardant in-situ polymerization gel electrolyte and its preparation method and application, the electrolyte preparation raw material includes A component, B component, C component and base electrolyte, A component is selected from isocyanate, B component is polyether amine monomer, C component is amino-terminated crosslinking agent, control A, B and C component allocation ratio and its total amount percentage of mass of base electrolyte;When applying, A component, B component, C component are uniformly dispersed in base electrolyte, in-situ polymerization reaction is carried out in battery, and in-situ polymerization gel electrolyte can be formed.The application directly in-situ polymerization forms polymer gel electrolyte in electrolyte, not only simplifies preparation process, but also greatly improves the interface performance of battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium batteries, in particular to a flame-retardant in-situ polymerization gel electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Liquid electrolytes are currently the mainstream products of commercial power batteries and digital batteries, but they have low flash points, low boiling points, and are flammable, and can easily cause fires and safety accidents under misuse and external force conditions. Therefore, it is urgent to develop electrolytes suitable for high specific energy and high safety.

[0003] Currently, researchers use inorganic all-solid-state electrolytes and polymer gel electrolytes to improve the safety of batteries. Among them, inorganic all-solid-state electrolytes theoretically do not contain liquid solvents and are safer, but conventional oxide and sulfide inorganic solid-state electrolytes cannot be mass-produced recently, have high costs, and cannot solve the problem of battery interface impedance. Polymer gel electrolytes have better ionic conductivity, lower interface impedance, and can inhibit solvent evaporation, and are more popular.

[0004] Currently, the preparation methods of conventional polymer gel electrolytes mainly include two routes:

[0005] (1) First, a porous membrane or a thin film that can absorb electrolyte is prepared, and electrolyte is added during battery assembly to achieve the gelation process.

[0006] (2) The precursor is added to the liquid electrolyte, and the in-situ gelation is realized after the electrolyte is injected. This route is compatible with the current industrialization of electrolyte injection and formation, and the battery impedance is lower, so it has more development prospects.

[0007] Currently, the in-situ polymer gel electrolyte precursors mainly include acrylate and cyclic ether. The former requires light and heat induction and initiators, and the latter uses the cyclic ether monomer itself as a solvent and requires a metal Lewis acid catalyst. However, initiators and metal catalysts can have potential adverse effects on battery performance, so it is necessary to develop an in-situ polymerization gel electrolyte without a catalyst and initiator system. SUMMARY

[0008] Therefore, it is necessary to provide a flame-retardant in-situ polymerization gel electrolyte and a preparation method and application thereof, which do not require a catalyst and initiator system, can simplify the preparation route of the gel electrolyte, and can guarantee or even improve the battery performance.

[0009] The present application adopts the following technical solutions:

[0010] The present application provides a kind of flame-retardant in-situ polymerization gel electrolyte, preparation raw material includes A component, B component, C component and base electrolyte;The A component is isocyanate, the B component is amino-terminated polyether amine, the C component is multi-functional amino-terminated crosslinking agent;The total amount of A, B and C component is 20%~80% of the mass percentage of total electrolyte;When application, A component, B component and C component are uniformly dispersed in electrolyte to form the total electrolyte, under the condition of 0 ℃~70 ℃, in inert gas environment, in-situ polymerization reaction is carried out, and in-situ polymerization gel electrolyte is formed.

[0011] In some embodiments, the isocyanate of A component can be one or more of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI) or hexamethylene diisocyanate (HDI), but not limited to the above-mentioned isocyanate.

[0012] In some embodiments, the amino-terminated polyether amine of B component can be one or more of D230, D400 or D2000, but not limited to the above-mentioned amino-terminated polyether amine.

[0013] In some embodiments, the amine value content of the polyether amine is 50~500 mg KOH / g, preferably, the amine value content of the polyether amine is specifically: the amine value content of D230 is 440~500 mg KOH / g, the amine value content of D400 is 220~273 mg KOH / g, and the amine value content of D2000 is 52~59 mg KOH / g.

[0014] In some embodiments, the multi-functional amino-terminated crosslinking agent of C component can be one or more of tris(2-aminoethyl)amine (TREA) or T403, but not limited to the above-mentioned multi-functional amino-terminated crosslinking agent. The amine value content of the multi-functional amino-terminated crosslinking agent T403 is preferably 322~390 mg KOH / g.

[0015] In some embodiments, the content of A, B and C components is adjusted so that the molar ratio of isocyanate (-NCO) and amino functional group (-NH2) is 0.5~1.5 (preferably 0.6~0.9), and the crosslinking degree of gel electrolyte ranges from 0.2 to 1 (preferably 0.4~0.8).

[0016] In some embodiments, the electrolyte is a lithium hexafluorophosphate-containing electrolyte.

[0017] The application can also provide a preparation method of the above-mentioned flame-retardant in-situ polymerization gel electrolyte, comprising the following steps: uniformly dispersing the component A in a proper amount of base electrolyte to form a mixed solution a; uniformly dispersing the component B and the component C in a proper amount of base electrolyte respectively to form a mixed solution b1 and a mixed solution b2, and then uniformly mixing the mixed solution b1 and the mixed solution b2 to form a mixed solution b; uniformly mixing the mixed solution a and the mixed solution b to form a total electrolyte, and then standing in an inert gas environment at a temperature of 0-70 ℃ to perform an in-situ polymerization reaction, thereby forming the in-situ polymerization gel electrolyte.

[0018] The application can also provide application of the above-mentioned flame-retardant in-situ polymerization gel electrolyte and the above-mentioned preparation method of the flame-retardant in-situ polymerization gel electrolyte in preparation of lithium batteries.

[0019] The application can also provide a lithium battery comprising a positive electrode, a negative electrode and the above-mentioned flame-retardant in-situ polymerization gel electrolyte.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] The preparation process of the flame-retardant in-situ polymerization gel electrolyte does not use initiators and metal catalysts, but only relies on in-situ polymerization reaction of the components A, B and C with a specific ratio in commercial electrolyte, thereby simplifying the preparation route of the gel electrolyte and ensuring the performance of battery charge-discharge cycle, electrochemical window and the like. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a preparation process route diagram of the in-situ polymerization gel electrolyte in the embodiments of the application.

[0023] Figure 2 It is a discharge specific capacity curve comparison (0.5C charge-discharge for 300 cycles after 0.1C charge-discharge for 5 cycles) of the gel electrolyte prepared in Example 1 and the comparative sample LB001.

[0024] Figure 3 It is an electrochemical window LVS curve diagram of the gel electrolyte in Example 1 and the electrolyte LB001.

[0025] Figure 4 It is a combustion test comparison of the gel electrolyte in Example 1 and the electrolyte LB001 (ignition condition: moving away after 15s of spray gun ignition). DETAILED DESCRIPTION

[0026] The application will be further described in detail below in combination with specific embodiments, so that those skilled in the art can more clearly understand the application.

[0027] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the specific embodiments of the invention without inventive effort are within the protection scope of the invention.

[0028] In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless otherwise specified, all technical means used are conventional means well known to those skilled in the art.

[0029] like Figure 1 As shown, the flame-retardant in-situ polymerized gel electrolyte in this embodiment of the invention comprises: component A is a commercial isocyanate, component B is a commercial amino-terminated polyetheramine, and component C is a multifunctional amino-terminated crosslinking agent. The preparation method of the in-situ polymerized gel electrolyte in this embodiment of the invention is as follows: components A, B, and C are uniformly dispersed in a base electrolyte, injected into a battery at 0℃~70℃, and allowed to stand in an inert gas environment to carry out an in-situ polymerization reaction, forming a flame-retardant in-situ polymerized gel electrolyte.

[0030] The following example illustrates this.

[0031] Key test material source description:

[0032] Basic electrolyte LB001: A commercial electrolyte containing 1M LiPF6 with EC / DMC as solvent at a volume ratio of 1:1.

[0033] Isocyanates: Isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), purchased from Aladdin.

[0034] TREA: Tris(2-aminoethyl)amine, purchased from Aladdin.

[0035] T403: Huntsman T403 curing agent.

[0036] Amino-terminated polyetheramines: D230 has an amine content of 440–500 mg KOH / g, D400 has an amine content of 220–273 mg KOH / g, and D2000 has an amine content of 52–59 mg KOH / g, purchased from Aladdin.

[0037] Example 1

[0038] The embodiment provides a fire-retardant in-situ polymerization gel electrolyte, which comprises an A component, a B component, a C component and a base electrolyte LB001, the A component is 0.3757g IPDI, the B component is 2.2g D2000, and the C component is 0.087g TREA. In the control system, the molar ratio of -NCO / -NH2 is 0.77, and the crosslinking degree is 0.41. The total mass percentage of the A component, the B component and the C component in the total electrolyte is 35wt%.

[0039] The preparation steps of the A component are as follows:

[0040] 0.3757g IPDI is added into a proper amount of base electrolyte LB001, and stirred at room temperature for 5-10min (the process is carried out in an argon-filled glove box), so that the IPDI is uniformly mixed to obtain a mixed solution a.

[0041] The preparation steps of the B component are as follows:

[0042] 2.2g D2000 is added into a proper amount of base electrolyte LB001, and stirred at room temperature for 5-10min (the process is carried out in an argon-filled glove box), so that the D2000 is uniformly mixed to obtain a mixed solution b1.

[0043] The preparation steps of the C component are as follows:

[0044] 0.087g crosslinking agent TREA is added into a proper amount of base electrolyte LB001, and stirred at room temperature for 2-5min (the process is carried out in an argon-filled glove box), so that the TREA is uniformly mixed to obtain a mixed solution b2.

[0045] The mixed solution b1 and the mixed solution b2 are uniformly mixed (stirred for 5-10min, and the process is carried out in an argon-filled glove box) to obtain a mixed solution b.

[0046] The in-situ gelation process is as follows: the mixed solution a and the mixed solution b are uniformly mixed (stirred for 10min, and the process is carried out in an argon-filled glove box) at room temperature (0-35℃) to form a total electrolyte, the total mass percentage of the A component, the B component and the C component in the total electrolyte is controlled to be 35%, and the in-situ polymerization reaction is carried out for 48h after standing, so that the in-situ polymerization gel electrolyte is obtained.

[0047] The embodiment also provides an application test method of the fire-retardant polymer gel electrolyte. The mixed solution b is injected into a button cell in a glove box, the positive electrode material is lithium iron phosphate, and the negative electrode material is a lithium sheet, and the electrochemical test is carried out after the reaction liquid is gelled.

[0048] The battery charge-discharge cycle curve (0.1C charge-discharge for 5 cycles, and then 0.5C charge-discharge for 300 cycles) is shown in Figure 2 The electrochemical window of the gel electrolyte and the commercial electrolyte LB001 is shown in Figure 3.

[0049] The results show that the electrolyte can gel in 48 hours, which is apparently a gel state that cannot flow. The viscosity of the electrolyte increases to 763 mPa*s in 24 hours. The electrochemical window test shows that it is stable at a voltage of 4.27 V. The first discharge specific capacity at 0.5C is 139.8 mAh / g, and the first charge-discharge efficiency is 89.4%; the discharge specific capacity after 300 cycles of 0.5C charge-discharge is 140 mAh / g, and the capacity retention rate is 100%.

[0050] Further, the gel electrolyte was tested for flame retardant performance by igniting it with a fire gun, and the results are shown in Table 2. Figure 4 The results show that the gel electrolyte can self-extinguish after being removed from the fire, and has good flame retardant performance.

[0051] Example 2

[0052] This example provides an in-situ polymerization gel electrolyte, which includes A component, B component and C component. The preparation method and application test method are basically the same as those of Example 1, except that 0.52g T403 is used to replace 0.087g TREA in the C component in this example.

[0053] Example 3

[0054] This example provides an in-situ polymerization gel electrolyte, which includes A component and B component. The preparation method and application test method are basically the same as those of Example 1, except that the combination of 0.188g D230 and 1.1g D2000 is used to replace 2.2g D2000 in the B component in this example.

[0055] Example 4

[0056] This example provides an in-situ polymerization gel electrolyte, which includes A component and B component. The preparation method and application test method are basically the same as those of Example 1, except that the combination of 0.273g D400 and 1.1g D2000 is used to replace 2.2g D2000 in the B component in this example.

[0057] Example 5

[0058] This example provides an in-situ polymerization gel electrolyte, which includes A component, B component and C component. The preparation method and application test method are basically the same as those of Example 1, except that 0.294g TDI is used to replace 0.3757g IPDI in the A component in this example.

[0059] Example 6

[0060] The embodiment provides an in-situ polymerization gel electrolyte, which comprises an A component, a B component and a C component. The preparation method and the application test method are basically the same as those of the embodiment 1, except that 0.422 g of MDI is used to replace 0.3757 g of IPDI in the A component in the embodiment.

[0061] Embodiment 7

[0062] The embodiment provides an in-situ polymerization gel electrolyte, which comprises an A component, a B component and a C component. The preparation method and the application test method are basically the same as those of the embodiment 1, except that 0.443 g of HMDI is used to replace 0.3757 g of IPDI in the A component in the embodiment.

[0063] Embodiment 8

[0064] The embodiment provides an in-situ polymerization gel electrolyte, which comprises an A component, a B component and a C component. The preparation method and the application test method are basically the same as those of the embodiment 1, except that 0.284 g of HDI is used to replace 0.3757 g of IPDI in the A component in the embodiment.

[0065] Embodiment 9

[0066] The embodiment provides an in-situ polymerization gel electrolyte, which comprises an A component, a B component and a C component. The preparation method and the application test method are basically the same as those of the embodiment 1, except that the A component is 0.3446 g of IPDI, and the molar ratio of -NCO / -NH2 is 0.71 in the embodiment.

[0067] Embodiment 10

[0068] The embodiment provides an in-situ polymerization gel electrolyte, which comprises an A component, a B component and a C component. The preparation method and the application test method are basically the same as those of the embodiment 1, except that 0.44 g of IPDI is used as the A component, 0.1258 g of TREA is used as the C component, and the crosslinking degree of the system is controlled to be 0.5 in the embodiment.

[0069] Embodiment 11

[0070] The embodiment provides an in-situ polymerization gel electrolyte, which comprises an A component, a B component and a C component. The preparation method and the application test method are basically the same as those of the embodiment 1, except that the A component is 0.7726 g of IPDI, the C component is 5.31 g of T403, the molar ratio of -NCO / -NH2 is 0.8, and the crosslinking degree of the system is 0.7 in the embodiment.

[0071] The application test method of the embodiment 1 is referred to, and the in-situ polymerization gel electrolytes in the embodiments 1 to 10 are tested respectively, and the test results are shown in the following table.

[0072] Application performance test statistics table of the gel electrolyte prepared in the test example

[0073]

[0074] As can be seen from the above table, by adjusting the content of components A, B and C, a gel can be formed after standing at 25°C for 48h. Due to the reaction between -NCO and amino functional groups during in-situ polymerization, the viscosity of the gel electrolyte is significantly increased after 24h, compared with the commercial electrolyte LB001.

[0075] Comparing Example 1 and 2, although the reactivity of T403 is weaker than that of TREA, the viscosity of T403 is larger, so the viscosity of T403 is still larger than that of Example 1 after 24h.

[0076] Comparing Example 1, 3 and 4, the results show that partial substitution of D2000 with D230 and D400 can accelerate the viscosity of the electrolyte, and the effect of D230 is more significant.

[0077] Comparing Example 1, 5, 6, 7 and 8, the results show that the viscosity of the electrolyte from high to low after 24h is TDI > MDI > HMDI > IPDI > HDI.

[0078] Comparing Example 1 and 9, the results show that the higher the content of IPDI, the larger the viscosity.

[0079] Comparing Example 1 and 10, the higher the content of component C, the larger the viscosity of the electrolyte.

[0080] The initial specific capacity, 300th cycle specific capacity, initial discharge efficiency and capacity retention rate after 300 cycles of the in-situ polymerized gel electrolyte in Test Examples 1 to 9 are slightly better than those of the liquid electrolyte LB001, but the gel electrolyte can self-extinguish away from fire and has flame-retardant effect. The electrochemical window LSV result of the gel electrolyte is slightly lower than that of LB001, but is still above 4.0V, which can meet the application requirements of traditional lithium iron phosphate positive electrode.

[0081] It is necessary to point out that the above examples are only for further elaboration and illustration of the technical solutions of the present application, and are not further limitations on the technical solutions of the present application. The method of the present application is only a preferred embodiment, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A flame-retardant in-situ polymerized gel electrolyte, characterized in that, The raw materials for preparation include component A, component B, component C and basic electrolyte, but do not include initiators and metal catalysts; Component A contains isocyanate, component B contains amino-terminated polyetheramine, and component C contains a multifunctional amino-terminated crosslinking agent. The total amount of components A, B, and C accounts for 35% to 80% of the total electrolyte by mass. The molar ratio of isocyanate to amino functional group is 0.6~0.9, and the degree of crosslinking is 0.4~0.8; The terminal amino polyetheramine includes D2000; The isocyanate is selected from one or more of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI) or hexamethylene diisocyanate (HDI); The multifunctional terminal amino crosslinking agent is selected from one or more of tris(2-aminoethyl)amine (TREA) or T403; The flame-retardant in-situ polymerized gel electrolyte is formed by uniformly dispersing components A, B, and C in a base electrolyte to form the total electrolyte, and then allowing it to stand in an inert gas environment at 0℃~70℃ to carry out an in-situ polymerization reaction to form the in-situ polymerized gel electrolyte.

2. The flame-retardant in-situ polymerized gel electrolyte according to claim 1, characterized in that, The terminal amino polyetheramine also includes one or more of D230 or D400.

3. The flame-retardant in-situ polymerized gel electrolyte according to claim 1, characterized in that, The amine content of the polyetheramine is 50~500 mg KOH / g, and the amine content of T403 is 322~390 mg KOH / g.

4. The flame-retardant in-situ polymerized gel electrolyte according to any one of claims 1 to 3, characterized in that, The basic electrolyte is an electrolyte containing lithium hexafluorophosphate.

5. A method for preparing a flame-retardant in-situ polymerized gel electrolyte as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Component A is uniformly dispersed in an appropriate amount of basic electrolyte to form mixture a; Components B and C are uniformly dispersed in an appropriate amount of basic electrolyte to form mixture b1 and mixture b2, and then mixture b1 and mixture b2 are uniformly mixed to form mixture b. Mixture a and mixture b are uniformly mixed to form the total electrolyte, and then... o C~70 o Under temperature C, the mixture is placed in an inert gas environment to undergo an in-situ polymerization reaction, forming an in-situ polymerized gel electrolyte.

6. The application of the flame-retardant in-situ polymerized gel electrolyte according to any one of claims 1 to 4 and the preparation method of the flame-retardant in-situ polymerized gel electrolyte according to claim 5 in the preparation of lithium batteries.

7. A lithium battery, characterized in that, It includes a positive electrode, a negative electrode, and a flame-retardant in-situ polymerized gel electrolyte as described in any one of claims 1 to 4.

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