A gel polymer electrolyte, a preparation method and application thereof

Abstract

The application discloses a gel polymer electrolyte and a preparation method and application thereof. The gel polymer electrolyte comprises monomers, an initiator, a lithium salt and an organic solvent. The monomers are provided with ether oxygen functional groups and carbonyl functional groups capable of conducting Li+. The initiator is selected from one of tin triflate and stannous octoate. The total mass ratio of the initiator and the monomers is 0.1-10:90-99. The mass ratio of the organic solvent and the lithium salt is 2-5:1. The application can realize the stability of the material to lithium metal without using a free radical polymerization mode represented by azobisisobutyronitrile, and can solve the problems of chemical reactions caused by initiator products and side reactions of residual active monomers by adjusting the adding proportion among the monomers, the initiator, the lithium salt and the organic solvent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a gel polymer electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Lithium metal batteries (LMBs) have attracted extensive attention due to their high theoretical specific capacity (3860 mAh / g). However, due to the high activity of the lithium metal anode, the liquid electrolyte (Liquid Electrode) will continuously react with it during the Li+ stripping / deposition process, leading to the failure and "dive" of the battery. From the perspective of safety, this is also a potential risk that can cause battery short circuit, fire or explosion. Gel polymer electrolytes (GPEs) are generally composed of a polymer backbone and a liquid electrolyte. The polymer backbone is usually composed of conductive ether or carbonate structures, and the material also exhibits a higher melting point compared to the liquid electrolyte. Researchers can also adjust the composition and function of the liquid electrolyte according to product requirements, thereby achieving the "synergistic effect" of the two media.

[0003] The use of gel polymer electrolytes to replace traditional liquid electrolytes will effectively improve the cycle performance and safety of lithium metal batteries. Gel polymer electrolytes are usually prepared by in-situ polymerization method, specifically: the prepared precursor is injected into the battery, and after a period of standing, the battery is given certain external intervention conditions (pressure / temperature / radiation), thereby obtaining in-situ polymerized gel polymer electrolyte. Generally, researchers usually choose free radical polymerization represented by azobisisobutyronitrile (AIBN), but this initiator will generate gas (N2) that is harmful to the battery, thereby worsening the positive and negative electrode interface contact of the battery, increasing the interface impedance, and reducing the electrochemical performance of the battery. At the same time, the problem of unreacted monomers and initiator residues also exacerbates the internal side reactions of the battery, further increasing the risk of battery failure. The application of the above technology to lithium metal batteries will also generate inorganic products such as LiN3 due to the high activity of Li, reducing the effective utilization rate, coulombic efficiency and energy density of Li metal.

[0004] Therefore, it is urgent to provide a gel polymer electrolyte and a preparation method and application thereof to solve the above technical problems. SUMMARY

[0005] The present application provides a gel polymer electrolyte and a preparation method and application thereof, which do not use free radical polymerization represented by azobisisobutyronitrile, solving the problems of chemical reactions caused by initiator products and side reactions of active monomer residues.

[0006] According to some embodiments, the present application provides a gel polymer electrolyte, comprising: a monomer, an initiator, a lithium salt and an organic solvent; the monomer is provided with ether oxygen functional groups and carbonyl functional groups capable of conducting Li+; the initiator is selected from one of tin triflate or stannous octoate; wherein the total mass ratio of the initiator and the monomer is 0.1-10:90-99; the mass ratio of the organic solvent and the lithium salt is 2-5:1.

[0007] Optionally, the monomer comprises a first monomer and a second monomer; the first monomer is selected from one or more of δ-valerolactone, ε-caprolactone, γ-valerolactone, β-butyrolactone, δ-caprolactone or a cyclic lactone structure; the second monomer is selected from 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide.

[0008] Optionally, the mass ratio of the first monomer and the second monomer is 63-93:7-40, such as 63:7, 81:19, 93:40.

[0009] Optionally, the organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, methyl ethyl carbonate.

[0010] Optionally, the lithium salt is selected from one or more of lithium triflate, lithium bistrifluoromethanesulfonimide, lithium tetrafluoroborate, lithium hexafluorophosphate or lithium difluoro(oxalato)borate.

[0011] Optionally, the total mass ratio of the initiator and the monomer is 1:99; the mass ratio of the organic solvent and the lithium salt is 3.3:1.

[0012] According to some embodiments, the present application also provides a preparation method of the gel polymer electrolyte, comprising the following steps:

[0013] adding a lithium salt in an organic solvent to mix to obtain a first solution; wherein the mass ratio of the organic solvent and the lithium salt is 2-5:1;

[0014] mixing a first monomer and a second monomer to obtain a second solution; wherein the mass ratio of the first monomer and the second monomer is 63-93:7-40;

[0015] mixing the obtained first solution and the second solution to obtain a third solution;

[0016] adding an initiator to the third solution to mix to obtain a fourth solution; wherein the total mass ratio of the initiator and the first monomer and the second monomer is 0.1-10:90-99;

[0017] The fourth solution is obtained into a gel polymer electrolyte under heating conditions.

[0018] Optionally, before the fourth solution is obtained into a gel polymer electrolyte under heating conditions, further comprising: introducing a certain amount of high-purity argon protective gas into the fourth solution and stirring thoroughly.

[0019] Optionally, the heating conditions include heating time, heating temperature and heating method; the heating time is 1 hr-24 hr, such as 5 hr, 8 hr, 12 hr, 18 hr, 20 hr; the heating temperature is 35℃-60℃, such as 35℃, 40℃, 45℃, 55℃, 60℃; and the heating method is one of water bath heating, oil bath heating, sand bath heating, air blowing heating or vacuum heating.

[0020] According to some embodiments, the application further provides an application of the gel polymer electrolyte, which is applied in a lithium metal battery.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] By adjusting the proportions of monomers, initiators, lithium salts and organic solvents, the stability of the material to lithium metal can be realized, and the monomer raw material used is a monomer capable of ring opening, which has ether oxygen functional groups (-O-) and carbonyl functional groups (C=O) capable of conducting Li+, which can conduct Li+ while also improving the dissociation of lithium salts. In addition, tin triflate or stannous octoate can be used as an initiator to initiate the ring opening of the multi-ring, and then in-situ polymerization inside the battery cell is carried out. In addition, Li-Sn alloy can be formed on the lithium metal negative side by the initiator Sn salt and metal lithium, thereby improving the subsequent lithium ion kinetics, and then improving the battery kinetics. In addition, through the mutual synergistic effect between the above-mentioned various substances, the problem of side reactions caused by the generation of initiators and the residual active monomers can be solved without using free radical polymerization represented by azobisisobutyronitrile. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0024] Figure 1 is a preparation flowchart of the preparation method of the gel polymer electrolyte in the embodiments of the application;

[0025] Figure 2 is a self-discharge graph of different groups in the embodiments of the present application;

[0026] Figure 3 is an enlarged view of the self-discharge graph of different groups in the embodiments of the present application. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present application, many technical details are presented in order to make the readers better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the following embodiments is for the convenience of description, and should not constitute any limitation on the specific implementation of the present application. The embodiments can be combined with each other and mutually referenced without contradiction.

[0028] The embodiments of the present application provide a gel polymer electrolyte and a preparation method and application. Without using a free radical polymerization mode represented by azobisisobutyronitrile, the problem of side reactions caused by initiator products and residual active monomers is solved.

[0029] A gel polymer electrolyte provided in the embodiments will be described in detail below. The gel polymer electrolyte mainly includes a monomer, an initiator, a lithium salt and an organic solvent. The monomer has ether oxygen functional groups and carbonyl functional groups capable of conducting Li+. The initiator is selected from one of tin triflate and stannous octoate. The total mass ratio of the initiator and the monomer is 0.1-10:90-99. The mass ratio of the organic solvent and the lithium salt is 2-5:1.

[0030] The monomer used in the embodiments has ether oxygen functional groups (-O-) and carbonyl functional groups (C=O) capable of conducting Li+. The monomer can also promote the dissociation of the lithium salt while conducting Li+. The initiator is selected from one of tin triflate and stannous octoate. The initiator can perform in-situ polymerization inside the battery cell and also form an alloy on the lithium metal negative electrode side, thereby improving the kinetic process of the battery. Thus, by adjusting the addition ratio of the monomer, the initiator, the lithium salt and the organic solvent, the embodiments of the present application can realize the stability of the material to lithium metal. Without using a free radical polymerization mode represented by azobisisobutyronitrile, the problem of side reactions caused by initiator products and residual active monomers can be solved. The gel polymer electrolyte prepared by using the above-mentioned substances can be applied in lithium metal batteries, can be compatible with the production and manufacturing process of current lithium ion batteries, and has the ability of large-scale production.

[0031] In the embodiment, it is to be noted that the monomer raw material is a monomer capable of ring opening, specifically including a first monomer and a second monomer, and the mass ratio of the first monomer to the second monomer is 63-93:7-40, and more preferably, the mass ratio of the first monomer to the second monomer is 81:19. The first monomer can be selected from one or more of δ-valerolactone, ε-caprolactone, γ-valerolactone, β-butyrolactone, δ-caprolactone or a cyclic lactone structure; and the second monomer can be selected from 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide. Preferably, the total mass ratio of the initiator and the monomers (the first monomer and the second monomer) in the embodiment is 1:99.

[0032] In the embodiment, it is also to be noted that the organic solvent can be selected from one or more of dimethyl carbonate, diethyl carbonate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and methyl ethyl carbonate; and the lithium salt can be selected from one or more of lithium triflate, lithium bistrifluoromethanesulfonimide, lithium tetrafluoroborate, lithium hexafluorophosphate, and lithium difluoro(oxalato)borate. Preferably, the mass ratio of the organic solvent to the lithium salt in the embodiment is 3.3:1.

[0033] Please refer to Figure 1 The embodiment of the present application also provides a preparation method of a gel polymer electrolyte, which comprises the following steps:

[0034] Step 1: adding a lithium salt into an organic solvent for mixing to obtain a first solution; wherein the mass ratio of the organic solvent to the lithium salt is 2-5:1;

[0035] The lithium salt is added into the organic solvent for sufficient stirring, and the first solution is obtained after mixing. The organic solvent can be selected from one or more of dimethyl carbonate, diethyl carbonate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and methyl ethyl carbonate; the lithium salt can be selected from one or more of lithium triflate, lithium bistrifluoromethanesulfonimide, lithium tetrafluoroborate, lithium hexafluorophosphate, and lithium difluoro(oxalato)borate; and the mass ratio of the organic solvent to the lithium salt is preferably mixed at a ratio of 3.3:1.

[0036] Step 2: mixing a first monomer and a second monomer to obtain a second solution; wherein the mass ratio of the first monomer to the second monomer is 63-93:7-40;

[0037] The first monomer and the second monomer are sufficiently stirred, and the second solution is obtained after mixing. The first monomer can be selected from one or more of δ-valerolactone, ε-caprolactone, γ-valerolactone, β-butyrolactone, δ-caprolactone or a cyclic lactone structure; the second monomer can be selected from 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide; and the mass ratio of the first monomer to the second monomer is preferably mixed at a ratio of 81:19.

[0038] Step 3: mixing the first solution and the second solution to obtain a third solution;

[0039] mixing the first solution obtained in step 1 and the second solution obtained in step 2 to obtain a third solution.

[0040] Step 4: adding an initiator into the third solution to obtain a fourth solution; wherein the total mass ratio of the initiator to the first monomer and the second monomer is 0.1-10:90-99;

[0041] weighing a certain amount of initiator, and mixing the weighed initiator into the third solution obtained in step 3 to obtain a fourth solution; wherein the initiator is one of tin triflate or stannous octoate, and preferably tin triflate; the initiator is mixed with the first monomer and the second monomer in a ratio of 1:99.

[0042] Step 5: introducing a certain amount of high-purity argon protective gas into the fourth solution and stirring thoroughly;

[0043] introducing a certain amount of protective gas such as high-purity argon into the fourth solution obtained in step 4 and stirring thoroughly.

[0044] Step 6: obtaining a gel polymer electrolyte under heating conditions.

[0045] obtaining a gel polymer electrolyte under heating conditions after treating the fourth solution in step 5, wherein the heating conditions include heating time, heating temperature and heating method; the heating time is 1 hr-24 hr, and preferably 12 hr; the heating temperature is 35℃-60℃, and preferably 40℃; the heating method is one of water bath heating, oil bath heating, sand bath heating, air blowing heating or vacuum heating, and preferably oil bath heating.

[0046] The gel polymer electrolyte can be prepared by using the above preparation method. In the preparation process, the mutual synergistic effect of the above various substances can realize the free radical polymerization mode represented by azobisisobutyronitrile without using the initiator, thereby solving the problems of chemical reaction caused by initiator product and side reaction of active monomer residue.

[0047] In order to better illustrate the effect of the embodiments of the present application, examples 1-5 and comparative examples 1-3 are used for illustration.

[0048] Example 1:

[0049] The present embodiment provides a gel polymer electrolyte, and the preparation method of the gel polymer electrolyte is as follows:

[0050] S1, 10 g of dimethyl carbonate (DMC) was weighed into a three-necked flask, then 3.03 g of lithium bisfluorosulfonylimide (LiFSI) was added, and fully stirred to obtain a first solution;

[0051] S2, 3.26 g of δ-valerolactone and 0.77 g of glycidyl 2,2,3,3-tetrafluoropropyl ether were weighed and fully dissolved and mixed to obtain a second solution;

[0052] S3, the first solution and the second solution obtained above were fully mixed to obtain a third solution;

[0053] S4, 0.04 g of tin triflate (Sn(OTf)2) was weighed and added to the third solution obtained above and fully mixed to obtain a fourth solution;

[0054] S5, a certain amount of high-purity argon was introduced into the three-necked flask, and the fourth solution was fully stirred;

[0055] S6, the reaction container was transferred into a 40°C oil bath, and reacted for 12 hr to obtain a gel polymer electrolyte (GPE).

[0056] Example 2

[0057] The present example provides a gel polymer electrolyte, and the preparation method thereof is as follows:

[0058] S1, 10 g of dimethyl carbonate (DMC) was weighed into a three-necked flask, then 3.03 g of lithium bisfluorosulfonylimide (LiFSI) was added, and fully stirred to obtain a first solution;

[0059] S2, 3.71 g of δ-valerolactone and 0.32 g of glycidyl 2,2,3,3-tetrafluoropropyl ether were weighed and fully dissolved and mixed to obtain a second solution;

[0060] S3, the first solution and the second solution obtained above were fully mixed to obtain a third solution;

[0061] S4, 0.04 g of tin triflate (Sn(OTf)2) was weighed and added to the third solution obtained above and fully mixed to obtain a fourth solution;

[0062] S5, a certain amount of high-purity argon was introduced into the three-necked flask, and the fourth solution was fully stirred;

[0063] S6, the reaction container was transferred into a 40°C oil bath, and reacted for 12 hr to obtain a gel polymer electrolyte (GPE).

[0064] Example 3

[0065] The embodiment provides a gel polymer electrolyte, and a preparation method of the gel polymer electrolyte is as follows:

[0066] S1, 10 g of dimethyl carbonate (DMC) is weighed in a three-necked flask, then 3.03 g of lithium bisfluorosulfonylimide (LiFSI) is added, and sufficient stirring is performed to obtain a first solution;

[0067] S2, 2.7 g of δ-valerolactone and 1.33 g of glycidyl 2,2,3,3-tetrafluoropropyl ether are weighed and fully dissolved and mixed to obtain a second solution;

[0068] S3, the first solution and the second solution obtained above are fully mixed to obtain a third solution;

[0069] S4, 0.04 g of tin triflate (Sn (OTf) 2) is weighed and added to the third solution obtained above and fully mixed to obtain a fourth solution;

[0070] S5, a certain amount of high-purity argon is introduced into the three-necked flask, and the fourth solution is fully stirred;

[0071] S6, the reaction container is transferred into a 40℃ oil bath, and reaction is performed for 12 hours to obtain a gel polymer electrolyte (GPEs).

[0072] Embodiment 4

[0073] The embodiment provides a gel polymer electrolyte, and a preparation method of the gel polymer electrolyte is as follows:

[0074] S1, 10 g of dimethyl carbonate (DMC) is weighed in a three-necked flask, then 3.03 g of lithium bisfluorosulfonylimide (LiFSI) is added, and sufficient stirring is performed to obtain a first solution;

[0075] S2, 3.26 g of ε-caprolactone and 0.77 g of glycidyl 2,2,3,3-tetrafluoropropyl ether are weighed and fully dissolved and mixed to obtain a second solution;

[0076] S3, the first solution and the second solution obtained above are fully mixed to obtain a third solution;

[0077] S4, 0.04 g of tin triflate (Sn (OTf) 2) is weighed and added to the third solution obtained above and fully mixed to obtain a fourth solution;

[0078] S5, a certain amount of high-purity argon is introduced into the three-necked flask, and the fourth solution is fully stirred;

[0079] S6, the reaction container is transferred into a 40℃ oil bath, and reaction is performed for 12 hours to obtain a gel polymer electrolyte (GPEs).

[0080] Example 5

[0081] S1, 10 g of dimethyl carbonate (DMC) was weighed in a three-necked flask, then 3.03 g of lithium bisfluorosulfonylimide (LiFSI) was added and fully stirred to obtain a first solution;

[0082] S2, 3.26 g of γ-valerolactone and 0.77 g of glycidyl 2,2,3,3-tetrafluoropropyl ether were weighed and fully dissolved and mixed to obtain a second solution;

[0083] S3, the first solution and the second solution obtained above were fully mixed to obtain a third solution;

[0084] S4, 0.04 g of tin trifluoromethanesulfonate (Sn(OTf)2) was weighed and added to the third solution obtained above and fully mixed to obtain a fourth solution;

[0085] S5, a certain amount of high-purity argon was introduced into the three-necked flask, and the fourth solution was fully stirred;

[0086] S6, the reaction vessel was transferred into a 40°C oil bath, and the reaction was carried out for 12 hr to obtain a gel polymer electrolyte (GPE).

[0087] Comparative Example 1:

[0088] S1, 10 g of dimethyl carbonate (DMC) was weighed in a three-necked flask, then 3.03 g of lithium bisfluorosulfonylimide (LiFSI) was added and fully stirred to obtain a first solution;

[0089] S2, 2.94 g of polyethylene glycol diacrylate and 1.09 g of glycidyl methacrylate were weighed and fully dissolved and mixed to obtain a second solution;

[0090] S3, the first solution and the second solution obtained above were fully mixed to obtain a third solution;

[0091] S4, 0.04 g of azobisisobutyronitrile (AlBN) was weighed and added to the third solution obtained above and fully mixed to obtain a fourth solution;

[0092] S5, a certain amount of high-purity argon was introduced into the three-necked flask, and the fourth solution was fully stirred;

[0093] S6, the reaction vessel was transferred into a 60°C oil bath, and the reaction was carried out for 12 hr to obtain a gel polymer electrolyte (GPE).

[0094] Comparative Example 2

[0095] S1, 10 g of dimethyl carbonate (DMC) was weighed into a three-necked flask, followed by the addition of 3.03 g of lithium bisfluorosulfonylimide (LiFSI) and thorough stirring to obtain a first solution;

[0096] S2, 3.02 g of trimethylolpropane triacrylate and 1.01 g of glycidyl methacrylate were weighed and thoroughly dissolved and mixed to obtain a second solution;

[0097] S3, the first solution and the second solution obtained above were thoroughly mixed to obtain a third solution;

[0098] S4, 0.04 g of azobisisobutyronitrile (AlBN) was weighed and added to the third solution obtained above and thoroughly mixed to obtain a fourth solution;

[0099] S5, a certain amount of high-purity argon gas was introduced into the three-necked flask, and the fourth solution was thoroughly stirred;

[0100] S6, the reaction vessel was transferred into a 60°C oil bath, and the reaction was carried out for 12 hr to obtain a gel polymer electrolyte (GPE).

[0101] Comparative Example 3

[0102] S1, 10 g of dimethyl carbonate (DMC) was weighed into a three-necked flask, followed by the addition of 3.03 g of lithium bisfluorosulfonylimide (LiFSI) and thorough stirring to obtain a first solution;

[0103] S2, 3.22 g of pentaerythritol triacrylate and 0.81 g of glycidyl acrylate were weighed and thoroughly dissolved and mixed to obtain a second solution;

[0104] S3, the first solution and the second solution obtained above were thoroughly mixed to obtain a third solution;

[0105] S4, 0.04 g of azobisisobutyronitrile (AlBN) was weighed and added to the third solution obtained above and thoroughly mixed to obtain a fourth solution;

[0106] S5, a certain amount of high-purity argon gas was introduced into the three-necked flask, and the fourth solution was thoroughly stirred;

[0107] S6, the reaction vessel was transferred into a 60°C oil bath, and the reaction was carried out for 12 hr to obtain a gel polymer electrolyte (GPE).

[0108] Analysis:

[0109] The positive electrode slurry was prepared according to the mass ratio of active material: conductive agent: binder = 97%: 1.5%: 1.5%, wherein the positive electrode was NCM88 (RNB Technology), the conductive agent was SP (Taimikao), and the binder was 5130 (Solenis, USA). Then, coating-drying-rolling-die cutting were performed to obtain dry electrode sheets. The separator was a single-sided ceramic coated separator (9um+2um+1um). The negative electrode was a lithium sheet with a diameter of 16mm and a thickness of 800um. The positive electrode sheet was cut to a diameter of 12mm. The precursor solution was prepared according to the above-mentioned Examples 1-5 and Comparative Examples 1-3, and then a 2032 button cell was assembled. The cell was heated according to the corresponding polymerization temperature, and finally tested. The voltage interval was 3.0V-4.2V, and the formation was performed at 0.1C / 0.1C small current for 2 cycles. Then, the cycle test was performed using a current density of 0.33C / 0.5C. The test results are shown in Table 1:

[0110] Table 1 Test results of different groups

[0111]

[0112] As can be seen from Table 1, the ICE of the comparative example group is significantly lower than that of the example group. This is because the use of azobisisobutyronitrile (AIBN) and acrylic ester formula can cause residual azobisisobutyronitrile, byproduct N2 and side reaction of lithium sheet, and the problem of not being resistant to high pressure. The charge capacity in Comparative Example 1 is significantly higher than that in other groups. This is because the residual monomer in the reaction has a significant side reaction at the high pressure stage, resulting in the deterioration of the battery interface.

[0113] A 2Ah soft package cell was assembled, and the cell was filled to capacity according to the current density of 0.33C. Then, the voltage was observed within a certain time after the cell was charged to 100% SOC. The voltage interval was 3.0V-4.3V. The self-discharge of the cell was detected every 1min, and the test results are shown in Figure 2 and Figure 3 .

[0114] As can be seen from Figure 2 and Figure 3 , the voltage of the battery in different groups will decrease after the charging is completed. However, the voltage of the comparative group (C1, C2, C3) decreases more significantly within the same time. This is also related to the actual situation of residual azobisisobutyronitrile (AIBN), byproduct N2 and side reaction of lithium sheet, and not being resistant to high pressure.

[0115] In addition, in Examples 1-5, a macrocycle is used as an initiator to open the ring in the first step to generate a transition state substance containing Sn 2+ (macrocycle-Sn 2+), and then the transition state attacks the three-membered ring to open the ring and form a gel; if only the macrocycle is used alone, the electrochemical stability of the material is poor and cannot meet the current long-term test process.

[0116] It should be understood that the foregoing detailed description of the application, rather than limiting the application, is provided for the purpose of illustration or explanation. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the application shall be included in the protection scope of the application. In addition, the appended claims of the application are intended to cover all variations and modifications falling within the scope and boundary of the appended claims, or the equivalent forms of such scope and boundary.

Claims

1. A gel polymer electrolyte, characterized by, Comprise: monomers, initiators, lithium salts and organic solvents; the monomers have ether oxygen functional groups and carbonyl functional groups capable of conducting Li+; the initiator is selected from one of tin triflate or stannous octoate; wherein the total mass ratio of the initiator and the monomers is 0.1-10:90-99; the mass ratio of the organic solvent and the lithium salt is 2-5:1; the monomers comprise first monomers and second monomers; the first monomers are cyclic lactone structures, and the cyclic lactone structures are selected from one or more of δ-valerolactone, ε-caprolactone, γ-valerolactone, β-butyrolactone, and δ-caprolactone; the second monomers are selected from 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide; the mass ratio of the first monomers and the second monomers is 63-93:7-40.

2. The gel polymer electrolyte of claim 1, wherein: the organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and methyl ethyl carbonate.

3. The gel polymer electrolyte of claim 1, wherein: the lithium salt is selected from one or more of lithium triflate, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium difluoro(oxalato)borate.

4. The gel polymer electrolyte of claim 1, wherein: the total mass ratio of the initiator and the monomers is 1:99; the mass ratio of the organic solvent and the lithium salt is 3.3:

1.

5. A method for producing the gel polymer electrolyte according to any one of claims 1 to 4, characterized by, The preparation method comprises the following steps: adding a lithium salt to an organic solvent to mix, obtaining a first solution; wherein the mass ratio of the organic solvent and the lithium salt is 2-5:1; mixing first monomers and second monomers to obtain a second solution; wherein the mass ratio of the first monomers and the second monomers is 63-93:7-40; mixing the obtained first solution and the second solution to obtain a third solution; adding an initiator to the third solution to mix, obtaining a fourth solution; wherein the total mass ratio of the initiator and the first monomers and second monomers is 0.1-10:90-99; obtaining a gel polymer electrolyte under heating conditions from the fourth solution.

6. The preparation method of the gel polymer electrolyte of claim 5, wherein: before obtaining the gel polymer electrolyte under heating conditions from the fourth solution, further comprising: introducing a certain amount of high-purity argon protective gas into the fourth solution and stirring thoroughly.

7. The preparation method of the gel polymer electrolyte of claim 5, wherein: the heating conditions comprise heating time, heating temperature, and heating method; the heating time is 1 hr-24 hr; the heating temperature is 35℃-60℃; the heating method is one of water bath heating, oil bath heating, sand bath heating, air blowing heating, or vacuum heating.

8. Use of the gel polymer electrolyte according to any one of claims 1 to 4, characterized in that, The gel polymer electrolyte is applied to a lithium metal battery.

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