Poss-containing borate single-ion conductor polymer gel electrolyte membranes and methods of making same

Abstract

The application discloses a borate single-ion conductor polymer gel electrolyte film containing POSS and a preparation method thereof, relates to the field of new energy solid electrolytes, and first synthesizes a borate single-ion conductor monomer, takes the monomer, double-bond-containing POSS and polyethylene glycol diacrylate (PEGDA) as monomers, and is combined with a crosslinking agent, in the presence of an initiator and reinforcing material PVDF-HFP, and is cured in situ by selecting a method combining light-induced curing and heat-induced curing, that is, light-induced radical polymerization is carried out under ultraviolet light irradiation, and then heat-induced polymerization is carried out in situ to form a three-dimensionally crosslinked single-ion conductor electrolyte film containing POSS organic-inorganic hybrid, and then the electrolyte film is soaked in an electrolyte to form a gel electrolyte film. The borate single-ion conductor polymer gel electrolyte film containing POSS provided by the application has the advantages of high safety performance, simple manufacturing method, low production cost, small environmental pollution and large-scale production, and the solid electrolyte has high lithium ion transference number and a wide electrochemical window.

Description

Technical Field

[0001] This invention relates to the field of new energy solid electrolytes, specifically to a borosilicate ester single-ion conductor polymer gel electrolyte membrane containing POSS and its preparation method. Background Technology

[0002] Lithium metal has an extremely high theoretical specific capacity (3860 mAh g). -1 Lithium metal batteries, using lithium metal as the negative electrode, have the highest energy density of all rechargeable batteries. The all-solid-state electrolyte eliminates the risk of leakage, improving battery safety. However, traditional solid-state electrolytes often suffer from low room-temperature ionic conductivity (<10). -6 Scm -1 Problems include low lithium-ion transference number (at 25℃), poor contact with the electrode, and excessive impedance.

[0003] Single-ion conductor polymer electrolytes possess lithium-ion transference numbers (LTVs) that are unmatched by other electrolytes, approaching 1. However, their low lithium-ion concentration, low room-temperature ionic conductivity, and poor compatibility with electrodes significantly limit their practical applications. Therefore, improving the ionic conductivity of single-ion conductor polymer electrolytes has attracted considerable attention from researchers.

[0004] There are two common methods to improve the ionic conductivity of single-ion conductor polymer electrolytes: one is to add plasticizers or lithium salts, such as organic electrolytes like PC, DOL, and DMC, so that the polymer absorbs the electrolyte and forms a gel electrolyte that is between a liquid and a solid electrolyte; the other approach is to add nano-inorganic particles or inorganic ceramic electrolytes to form a composite electrolyte. However, inorganic particles are prone to agglomeration and have poor contact with the electrode interface, resulting in high interfacial impedance and poor compatibility between the organic and inorganic phases. This leads to still low ionic conductivity, the presence of lithium dendrites, and unsatisfactory compatibility between the electrolyte and the electrode. Summary of the Invention

[0005] To address the problems of existing technologies, the present invention aims to overcome the shortcomings of existing technologies and provide a borate ester single-ion conductor monomer and its preparation method. This substance is then applied to the preparation of a POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane, resulting in a special type of organic-inorganic hybrid electrolyte that combines the advantages of POSS and single-ion conductor electrolytes, as well as the advantages of composite electrolytes and gel electrolytes. It possesses both high mobility number, ionic conductivity, and excellent interfacial stability.

[0006] One of the objectives of this invention is to provide a borate ester single-ion conductor monomer, the specific technical solution of which is as follows:

[0007] A borate ester single-ion conductor monomer, comprising lithium diallyl malonate ester, having a structure containing two double bonds, with the specific structural formula as follows:

[0008]

[0009] The second objective of this invention is to provide a method for preparing the above-mentioned dielyl malonate borate lithium salt, the specific technical solution of which is as follows:

[0010] A method for synthesizing lithium diallyl malonate borate, comprising the following steps:

[0011] Boric acid, lithium carbonate, and allyl diacid were placed in anhydrous acetonitrile and reacted under a protective atmosphere at a reaction temperature of 60–90 °C for 10–18 h. After cooling, filtration, washing, and a first drying treatment, lithium diallyl malonate boronic acid ester was obtained.

[0012] The third objective of this invention is to provide a borosilicate single-ion conductor polymer electrolyte containing POSS, the specific technical solution of which is as follows:

[0013] A POSS-containing borate ester single-ion conductor polymer electrolyte comprises: a POSS structure, a borate ester structure, and an EO-rich single-ion conductor polymer structure, wherein the molar ratio of ethoxy groups to lithium ions in the POSS-containing borate ester single-ion conductor electrolyte is 6–18:1.

[0014] The fourth objective of this invention is to provide a method for preparing a borosilicate ester single-ion conductor polymer electrolyte containing POSS, the specific technical solution of which is as follows:

[0015] A method for preparing a POSS-containing borosilicate ester single-ion conductor polymer gel electrolyte, comprising in-situ curing via a combination of photo-initiated curing and thermally-initiated curing, including the following steps:

[0016] S1. Dissolve each component of the raw material in a solvent solution, stir and mix evenly to prepare a mixture, wherein the raw material includes: borate ester monoionic conductor monomer, polyethylene glycol diacrylate and cage-type polysilsesquioxane containing double bonds as polymerizing monomers, poly(vinylidene fluoride-hexafluoropropylene) as supporting and reinforcing material, a substance containing four double bond functional groups as a crosslinking agent, and an initiator, wherein the initiator includes thermal initiators and photoinitiators;

[0017] S2. The mixture is subjected to ultraviolet light irradiation for photoinitiated curing to obtain a photopolymer.

[0018] S3. The photopolymer is subjected to solvent removal treatment and then thermally initiated curing treatment to obtain an initial film;

[0019] S4. The initial film is washed to obtain a washed film;

[0020] S5. The washing film is subjected to a second drying treatment to obtain the POSS-containing borate ester single-ion conductor polymer electrolyte.

[0021] Furthermore, the specific amounts of each substance, expressed in parts by mass, are as follows:

[0022] The poly(vinylidene fluoride-hexafluoropropylene): 10-25 parts;

[0023] The polyethylene glycol diacrylate: 10-45 parts;

[0024] The crosslinking agent containing four double bonds: 10-35 parts;

[0025] The boronic acid ester lithium salt containing two double bonds: 10-35 parts;

[0026] The cage-like polysilsesquioxane containing double bonds: no more than 15 parts

[0027] The photoinitiator: no more than 0.04 parts;

[0028] The thermal initiator: no more than 0.06 parts.

[0029] Furthermore, the borate ester single-ion conductor monomer is selected from lithium diallyl malonate borate or lithium dicibutenedioate borate; the double-bonded POSS substance is selected from heptaisobutylmethacryloxypropyl cage polysilsesquioxane, heptaisooctylmethacryloxypropyl cage polysilsesquioxane, heptaphenylvinyl cage polysilsesquioxane, or heptaphenylallyl cage polysilsesquioxane; the substance containing four double-bonded functional groups is selected from pentaerythritol tetra(mercaptoacetic acid) ester or pentaerythritol tetramethacrylate; the photoinitiator is selected from benzoin diethyl ether; and the thermal initiator is selected from azobisisobutyronitrile.

[0030] Furthermore, the solvent solution is a mixture of two of N,N-dimethylformamide, acetonitrile, or isopropanol.

[0031] Furthermore, the photo-initiated curing treatment is a UV irradiation treatment using 365nm UV light for 15–45 minutes; the solvent removal treatment, the thermal initiation curing treatment, and the second drying treatment are all performed under vacuum and 60°C conditions for 6–24 hours; the washing treatment uses anhydrous ethanol; and the second drying treatment lasts for 12 hours.

[0032] The fifth objective of this invention is to provide a method for preparing a POSS-containing borosilicate single-ion conductor polymer electrolyte membrane by applying the above-mentioned POSS-containing borosilicate single-ion conductor polymer gel electrolyte membrane. The specific technical solution is as follows:

[0033] The preparation method of the POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane includes the following steps: immersing the POSS-containing borate ester single-ion conductor polymer electrolyte in an electrolyte solution to form a gel electrolyte membrane, wherein the electrolyte solution is a solution containing one or both of ethylene carbonate and dimethyl carbonate.

[0034] The sixth objective of this invention is to provide a borosilicate single-ion conductor polymer gel electrolyte membrane containing POSS, the specific technical solution of which is as follows:

[0035] The POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane is prepared using the above-mentioned preparation method of the POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane, and has a lithium-ion transference number of more than 0.7 and an electrochemical window of more than 5.0.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] This invention provides a method for preparing a borate ester single-ion conductor monomer, and applies the prepared borate ester single-ion conductor monomer to the preparation of a POSS-containing borate ester single-ion conductor polymer gel electrolyte. By introducing the POSS structure into the borate ester single-ion conductor monomer through covalent bonds, in-situ curing is carried out by a combination of photo-initiated curing and thermal-initiated curing to obtain a novel three-dimensional crosslinked borate ester single-ion conductor gel electrolyte. This novel electrolyte has a high lithium-ion transference number, a wide electrochemical window, and good electrolyte-electrode compatibility. Batteries assembled from it have good cycle stability.

[0038] The POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane prepared by this invention has the advantages of high safety performance, simple manufacturing method, low production cost, low environmental pollution, and large-scale production capability. Attached Figure Description

[0039] Figure 1 The NMR spectrum of lithium diallyl malonate borate (LiBAMB) prepared in Example 1 of this invention;

[0040] Figure 2 The impedance spectrum of the POSS-BSIPE-1-GPE sample prepared in Example 8 of this invention was tested at 25°C.

[0041] Figure 3The impedance spectrum of the POSS-BSIPE-1-GPE sample prepared in Example 8 of this invention was tested at 55°C. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] To facilitate understanding, the English nouns and abbreviations mentioned below will be explained first:

[0044] PVDF-HFP: Poly(vinylidene fluoride-hexafluoropropylene)

[0045] PEGDA: Polyethylene glycol diacrylate

[0046] PETMP: Pentaerythritol tetra(thioglycolic acid) ester

[0047] LiBAMB: Lithium Diallyl Malonate Borate

[0048] LiTFSI: Lithium Bis(trifluoromethanesulfonyl)imide

[0049] POSS: Cage-type polysilsesquioxane

[0050] MAPOSS: Heptaisobutylmethacryloyloxypropyl cage-type polysilsesquioxane

[0051] O-POSS: Hepta-Octyl Methacryloxypropyl POSS

[0052] DMPA: Benzoin Diethyl Ether

[0053] AIBN: Azobisisobutyronitrile

[0054] DMF: N,N-Dimethylformamide

[0055] EO: Ethoxy

[0056] EC: Ethylene carbonate

[0057] DMC: Dimethyl carbonate

[0058] Ohm: also represented by Ω, ohm

[0059] In this specific embodiment, three substances and their preparation methods are provided: borate ester single-ion conductor monomers and their preparation methods, POSS-containing borate ester single-ion conductor polymer electrolytes and their preparation methods, and POSS-containing borate ester single-ion conductor polymer gel electrolyte membranes and their preparation methods.

[0060] Example 1:

[0061] This embodiment uses the synthesis of lithium diallyl malonate borate (LiBAMB) as an example to introduce the preparation method of borate ester single-ion conductor monomers. The specific steps are as follows:

[0062] 105 mmol of boric acid, 60 mmol of lithium carbonate, and 200 mmol of allyl diacid were placed in anhydrous acetonitrile and reacted under a protective atmosphere at a reaction temperature of 60–90 °C for 10–18 h. After cooling, filtration, washing, and a first drying process, a pale yellow powder monomer, namely LiBAMB, was obtained and stored under a protective atmosphere for later use.

[0063] In this embodiment, the reaction temperature is 80°C and the reaction time is 12 hours.

[0064] In this embodiment, the protective atmosphere is a nitrogen atmosphere.

[0065] It should be noted that anhydrous acetonitrile is used as a solvent to dissolve substances such as boric acid, lithium carbonate, and allyl diacid. The principle for the amount of solvent used is to dissolve all substances. In this example, the amount of solvent used is 1000 ml.

[0066] The NMR spectrum of LiBAMB is as follows: Figure 1 As shown, the molecular structure of LiBAMB is determined as follows:

[0067]

[0068] This structure contains two double bonds.

[0069] Example 2:

[0070] This embodiment describes a method for preparing a borosilicate single-ion conductor polymer electrolyte containing POSS, specifically including the following steps:

[0071] S1. Dissolve the raw materials in a solvent solution and stir to mix evenly to prepare a mixture. The raw materials are: borate ester monoionic conductor monomer, PEGDA and POSS containing double bonds as polymer monomers, PVDF-HFP as supporting and reinforcing material, a substance containing four double bond functional groups as a crosslinking agent, and initiators (including thermal initiators and photoinitiators).

[0072] S2. Pour the mixture into a mold and perform photo-initiated curing to obtain a photopolymer.

[0073] S3. The above-mentioned photopolymer is subjected to solvent removal and thermal curing to obtain an initial film;

[0074] S4. The initial film is washed to remove unreacted borate ester single-ion conductor monomers and initiators to obtain a washed film.

[0075] S5. The washing membrane is subjected to a second drying treatment to obtain a solid polymer electrolyte containing POSS;

[0076] Furthermore, the borate ester single-ion conductor monomer can be selected from one or both of LiBAMB or lithium dicis-butenedioic acid borate ester.

[0077] Furthermore, the POSS substance containing double bonds is selected from one or more of heptaisobutylmethacryloyloxypropyl cage polysilsesquioxane (MAPOSS), heptaisooctylmethacryloyloxypropyl POSS, heptaphenylvinyl POSS, or heptaphenylallyl POSS.

[0078] Furthermore, the substance containing four double bond functional groups is selected from one or both of PETMP or pentaerythritol tetramethacrylate.

[0079] Specifically, in this embodiment, the borate ester single-ion conductor monomer is LiBAMB, the POSS substance containing double bonds is MAPOSS, the substance containing four double-bonded functional groups is PETMP, and the initiators are AIBN (as a thermal initiator) and DMPA (as a photoinitiator).

[0080] It should be noted that the average molecular weight of PVDF-HFP is 300,000 to 600,000, while the average molecular weight of PEGDA is approximately 1,000.

[0081] More specifically, in this embodiment, PVDF-HFP, PEGDA, PETMP, LiBAMB, MAPOSS, DMPA, and AIBN are configured in a mass ratio of 23:35:29:25:5:0.0025:0.0025.

[0082] It should be noted that the ethoxy chain segment (-CH2CH2-O-, abbreviated as EO) in PEGDA and the Li in LiBAMB... + The preferred molar ratio is 6 to 18:1. In this embodiment, the ratio is 8:1.

[0083] Furthermore, the solvent solution is a mixture of two of DMF, acetonitrile, or isopropanol.

[0084] Furthermore, the solvent solution is a mixed solution of DMF and isopropanol, and the volume ratio of DMF to isopropanol can range from 1:1 to 20:1. In this embodiment, the ratio is 1:1.

[0085] In this embodiment, in step S1, the stirring and mixing time is 1 hour to ensure the formation of a homogeneous mixed solution.

[0086] In this embodiment, in step S2, the mold is made of polytetrafluoroethylene.

[0087] Furthermore, in step S2, the photo-initiated curing treatment is performed using ultraviolet light irradiation.

[0088] Specifically, in this embodiment, in step S2, the ultraviolet irradiation treatment uses 365nm ultraviolet light for 30 minutes.

[0089] Furthermore, in step S3, both the solvent removal treatment and the thermally initiated curing treatment involve removing the solvent in a vacuum oven, with a drying time of 6–24 hours.

[0090] Specifically, in this embodiment, in step S3, the solvent removal and thermal initiation curing processes are carried out under vacuum and 60°C conditions. The heat preservation time for the solvent removal process is 6 hours, and the heat preservation time for the thermal initiation curing process is 12 hours.

[0091] In this embodiment, in step S4, the initial film is washed twice with anhydrous ethanol to remove unreacted monomers and initiators.

[0092] In this embodiment, the second drying process in step S5 is specifically: keeping the temperature at 60°C under vacuum for 12 hours.

[0093] The POSS-containing solid polymer electrolyte prepared in this embodiment is labeled as: POSS-BSIPE-1.

[0094] Example 3:

[0095] This embodiment describes a method for preparing a borosilicate ester single-ion conductor polymer electrolyte containing POSS. The steps are basically the same as in Example 2, with the difference being:

[0096] In this embodiment, PVDF-HFP, PEGDA, PETMP, LiBAMB, MAPOSS, DMPA, and AIBN are configured in a mass ratio of 20:35:35:25:10:0.004:0.006.

[0097] In this embodiment, the ultraviolet light irradiation treatment time in step S2 is 45 minutes.

[0098] In this embodiment, the heat treatment time for thermal initiation curing in step S3 is 10 hours.

[0099] In this embodiment, the solid polymer electrolyte containing POSS obtained in step S5 is labeled as: POSS-BSIPE-2.

[0100] Example 4:

[0101] This embodiment describes a method for preparing a borosilicate ester single-ion conductor polymer electrolyte containing POSS. The steps are basically the same as in Example 2, with the difference being:

[0102] In this embodiment, PVDF-HFP, PEGDA, PETMP, LiBAMB, MAPOSS, DMPA, and AIBN are configured in a mass ratio of 20:35:29:25:15:0.006:0.004.

[0103] In this embodiment, the ultraviolet light irradiation treatment time in step S2 is 15 minutes.

[0104] In this embodiment, the heat-initiated curing treatment in step S3 is kept at a temperature of 24 hours.

[0105] In this embodiment, the solid polymer electrolyte containing POSS obtained in step S5 is labeled as: POSS-BSIPE-3.

[0106] Example 5:

[0107] This embodiment describes a method for preparing a borosilicate ester single-ion conductor polymer electrolyte containing POSS. The steps are basically the same as in Example 2, with the difference being:

[0108] In this embodiment, PVDF-HFP, PEGDA, PETMP, LiBAMB, MAPOSS, DMPA, and AIBN are configured in a mass ratio of 10:35:10:25:0.001:0.0001:0.0099.

[0109] In this embodiment, the ultraviolet light irradiation treatment time in step S2 is 30 minutes.

[0110] In this embodiment, the heat-initiated curing treatment in step S3 is kept at a temperature of 12 hours.

[0111] In this embodiment, the solid polymer electrolyte containing POSS obtained in step S5 is labeled as: POSS-BSIPE-4.

[0112] Example 6:

[0113] This embodiment describes a method for preparing a borosilicate ester single-ion conductor polymer electrolyte containing POSS. The steps are basically the same as in Example 2, with the difference being:

[0114] In this embodiment, PVDF-HFP, PEGDA, PETMP, LiBAMB, O-POSS, DMPA, and AIBN are configured in a mass ratio of 10:14:10:10:10:0.004:0.006.

[0115] In this embodiment, the ultraviolet light irradiation treatment time in step S2 is 30 minutes.

[0116] In this embodiment, the heat-initiated curing treatment in step S3 is kept at a temperature of 12 hours.

[0117] In this embodiment, the solid polymer electrolyte containing POSS obtained in step S5 is labeled as: POSS-BSIPE-5.

[0118] Example 7:

[0119] This embodiment describes a method for preparing a borosilicate ester single-ion conductor polymer electrolyte containing POSS. The steps are basically the same as in Example 2, with the difference being:

[0120] In this embodiment, PVDF-HFP, PEGDA, PETMP, LiBAMB, O-POSS, DMPA, and AIBN are configured in a mass ratio of 10:45:35:35:15:0.04:0.06.

[0121] In this embodiment, the ultraviolet light irradiation treatment time in step S2 is 30 minutes.

[0122] In this embodiment, the heat-initiated curing treatment in step S3 is kept at a temperature of 12 hours.

[0123] In this embodiment, the solid polymer electrolyte containing POSS obtained in step S5 is labeled as: POSS-BSIPE-6.

[0124] Example 8:

[0125] This embodiment describes a method for preparing a borosilicate ester single-ion conductor polymer gel electrolyte membrane containing POSS. The specific steps are as follows:

[0126] A POSS-containing solid polymer electrolyte is immersed in an electrolyte solution to obtain a POSS-containing borate ester single-ion conductor gel electrolyte membrane.

[0127] Furthermore, the electrolyte is a mixed solution containing EC and DMC.

[0128] In this embodiment, the solid polymer electrolyte containing POSS is selected from the POSS-BSIPE-1 prepared in Example 2.

[0129] In this embodiment, a mixed solution of EC and DMC prepared at a volume ratio of 1:1 is selected as the electrolyte.

[0130] In this embodiment, the prepared POSS borate ester single-ion conductor gel electrolyte membrane is labeled as: POSS-BSIPE-1-GPE

[0131] Example 9:

[0132] This embodiment describes the preparation method of a POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane. The steps are basically the same as those in Example 8, except that the POSS-containing solid polymer electrolyte is POSS-BSIPE-2 prepared in Example 3, and the prepared POSS-containing borate ester single-ion conductor gel electrolyte membrane is labeled as POSS-BSIPE-2-GPE.

[0133] Example 10:

[0134] This embodiment describes the preparation method of a POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane. The steps are basically the same as those in Example 8, except that the POSS-containing solid polymer electrolyte is POSS-BSIPE-3 prepared in Example 4, and the prepared POSS-containing borate ester single-ion conductor gel electrolyte membrane is labeled as POSS-BSIPE-3-GPE.

[0135] Example 11:

[0136] This embodiment describes the preparation method of a POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane. The steps are basically the same as those in Example 8, except that the POSS-containing solid polymer electrolyte is POSS-BSIPE-4 prepared in Example 5, and the prepared POSS-containing borate ester single-ion conductor gel electrolyte membrane is labeled as POSS-BSIPE-4-GPE.

[0137] Example 12:

[0138] This embodiment describes the preparation method of a POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane. The steps are basically the same as those in Example 8, except that the POSS-containing solid polymer electrolyte is POSS-BSIPE-5 prepared in Example 6, and the prepared POSS-containing borate ester single-ion conductor gel electrolyte membrane is labeled as POSS-BSIPE-5-GPE.

[0139] Example 13:

[0140] This embodiment describes the preparation method of a POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane. The steps are basically the same as those in Example 8, except that the POSS-containing solid polymer electrolyte is POSS-BSIPE-6 prepared in Example 7, and the prepared POSS-containing borate ester single-ion conductor gel electrolyte membrane is labeled as POSS-BSIPE-6-GPE.

[0141] Comparative Example 1:

[0142] PVDF-HFP, PEGDA, PETMP, LiBAMB, DMPA and AIBN were placed in DMF solvent in a mass ratio of 20:35:15:25:0.005:0.005 and stirred for 1 hour to form a homogeneous mixed solution.

[0143] The mixed solution was poured into a polytetrafluoroethylene mold and irradiated under ultraviolet light (365nm) for 30 minutes. The mold was then placed in a vacuum oven at 60°C for 6 hours to remove the solvent. The mold was then kept at 60°C for 12 hours for vacuum drying to obtain the initial film.

[0144] The initial film was ultrasonically washed twice in anhydrous ethanol to remove unreacted substances, resulting in a washed film.

[0145] The washing film was placed in a vacuum oven at 60°C for 12 hours for vacuum drying to obtain a POSS-free solid polymer electrolyte, labeled as BSIPE, in which the molar ratio of EO to Li was 8:1.

[0146] A POSS-free solid polymer electrolyte is immersed in an electrolyte solution to obtain a POSS-free borate ester single-ion conductor gel electrolyte membrane, BSIPE-GPE.

[0147] Comparative Example 2:

[0148] Poly(vinylidene fluoride-hexafluoropropylene) and PEGDA were placed in DMF at a mass ratio of 23:25 and stirred at 80°C for 18 hours to ensure complete dissolution. LiTFSI was then added to the solution, with the addition ratio of Li in LiTFSI to EO in poly(vinylidene fluoride-hexafluoropropylene) being 1:10. The mixture was stirred for another 6 hours to obtain a mixed solution.

[0149] The mixed solution was poured into a polytetrafluoroethylene mold, and the mold was placed in a vacuum oven at 60°C to remove the solvent and dry it, thus obtaining a POSS-free solid polymer electrolyte.

[0150] A solid polymer electrolyte without POSS was immersed in an electrolyte solution to obtain a polymer gel electrolyte membrane blank-GPE.

[0151] The performance tests of each embodiment and comparative example are described below.

[0152] The corresponding polymer electrolyte membrane samples prepared in Example 3 and Comparative Example 1 were subjected to DSC and mechanical property tests at room temperature to evaluate their glass transition temperature and mechanical strength. The results are shown in Table 1. The glass transition temperature can reflect its crystallinity. A decrease in glass transition temperature indicates a decrease in polymer crystallinity.

[0153] Table 1. Glass transition temperature and mechanical strength of the polymer electrolyte samples prepared in Example 3 and Comparative Example 1.

[0154] Example 3 - POSS - BSIPE-2 -8.75 3.7 Comparative Example 1 - BSIPE -3.74 2.1

[0155] As can be seen from Table 1, introducing POSS into the polymer electrolyte system reduces the glass transition temperature, decreases the crystallinity of the polymer matrix, and improves the mechanical properties.

[0156] The impedance spectra of the POSS-BSIPE-1-GPE sample prepared in Example 8 were measured at 25°C and 55°C, as shown below. Figure 2 and Figure 3 As shown, the spectrum is composed of a semicircle in the high-frequency region and a 45° straight line in the low-frequency region, where the x-coordinate of the intersection point of the semicircle and the straight line is Z. 1 The value of (Ω) is used as the volume resistance R (Ω) of the POSS-BSIPE-1-GPE sample.

[0157] The electrolyte membrane samples prepared in Examples 8 to 13, as well as Comparative Examples 1 and 2, were used to assemble CR2016, 2032, and 2025 lithium-ion batteries for testing electrolyte ionic conductivity, transport number, and electrochemical window. Ionic conductivity was tested at 25°C with a frequency range of 1 MHz to 0.1 Hz and a perturbation voltage of 5 mV. Transport number was tested with a polarization voltage of 0.01 V and a polarization time of 2000 s. Electrochemical stability was tested at 25°C with a voltage range of 0 to 7 V and a scan rate of 10 mV / s. The results are shown in Table 2.

[0158] Table 2. Lithium-ion transport numbers and electrochemical windows of the electrolyte membrane samples prepared in Examples 8-13 and Comparative Examples 1-2.

[0159]

[0160]

[0161] Table 2 shows the electrochemical window and migration number of the POSS-containing borate ester single-ion conductor gel electrolyte membranes prepared in Examples 8 to 13. It can be seen that the migration number and electrochemical window of the POSS-containing solid polymer electrolytes in the six examples are significantly better than the corresponding data in the two comparative examples. This is mainly because the POSS single-ion conductor electrolyte described in this invention combines the advantages of both POSS and borate ester single-ion conductor electrolytes, and is a special type of organic-inorganic hybrid electrolyte; the POSS single-ion conductor gel electrolyte combines the advantages of composite electrolytes and gel electrolytes. Therefore, it possesses both high migration number and usable ionic conductivity, as well as a wide electrochemical window and excellent interfacial stability.

[0162] In summary, this invention introduces the POSS structure into a single-ion conductor polymer to prepare a POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane. It can be seen that POSS-containing materials are organic-inorganic nanohybrid materials with a unique nanoscale cage structure. POSS has unique advantages in modifying solid polymer electrolytes. Introducing POSS into the polymer electrolyte system reduces the crystallinity of the polymer matrix, effectively suppresses lithium dendrites, enhances ion transport capacity, promotes lithium ion conduction, and improves electrochemical stability, thermal stability, and mechanical properties of the film. Simultaneously, it improves interfacial compatibility with the electrode. Single-functional or multi-functional POSS, while serving as a nanofiller, can also participate in polymerization reactions, becoming part of the polymer molecular chain, achieving molecular-level hybridization. Compared to the traditional physical mixing of inorganic particles and polymer electrolytes, its hybridization effect and improvement of interfacial compatibility between the electrolyte and the electrode are superior.

[0163] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A borosilicate single-ion conductor polymer electrolyte containing POSS, characterized in that, The structure of the POSS-containing borate ester single-ion conductor polymer electrolyte includes: a POSS structure, a borate ester structure, and a single-ion conductor polymer structure rich in EO segments. The molar ratio of ethoxy groups to lithium ions in the POSS-containing borate ester single-ion conductor electrolyte is 6 to 18:

1. The POSS structure is a cage-like polysilsesquioxane containing double bonds, and the cage-like polysilsesquioxane containing double bonds is selected from one of heptaisobutylmethacryloyloxypropyl cage-like polysilsesquioxane, heptaisooctylmethacryloyloxypropyl cage-like polysilsesquioxane, heptaphenylvinyl cage-like polysilsesquioxane or heptaphenylallyl cage-like polysilsesquioxane. The borate ester structure is a borate ester single-ion conductor monomer, and the borate ester single-ion conductor monomer is selected from lithium diallyl malonate borate or lithium dicibutenedioate borate. The EO-rich single-ion conductor polymer structure is polyethylene glycol diacrylate; The preparation method of the POSS-containing borate ester single-ion conductor polymer electrolyte involves in-situ curing through a combination of photo-initiated curing and thermally-initiated curing, and includes the following steps: S1. Dissolve each component of the raw material in a solvent solution, stir and mix evenly to prepare a mixture, wherein the raw material includes, as a polymerization monomer, a borate ester monoionic conductor monomer, polyethylene glycol diacrylate and a cage-like polysilsesquioxane containing double bonds, as a supporting and reinforcing material, poly(vinylidene fluoride-hexafluoropropylene), as a crosslinking agent, a substance containing four double bond functional groups, and an initiator, wherein the initiator includes thermal initiators and photoinitiators; S2. The mixture is subjected to ultraviolet light irradiation for photoinitiated curing to obtain a photopolymer. S3. The photopolymer is subjected to solvent removal treatment and then thermally initiated curing treatment to obtain an initial film; S4. The initial film is washed to obtain a washed film; S5. The washing film is subjected to a second drying treatment to obtain the POSS-containing borate ester single-ion conductor polymer electrolyte.

2. The porosilicate single-ion conductor polymer electrolyte containing POSS according to claim 1, characterized in that, The lithium diallyl malonate borate salt has a structure containing two double bonds, and its specific structural formula is as follows: 。 3. The porosilicate single-ion conductor polymer electrolyte containing POSS according to claim 2, characterized in that, The preparation method of the lithium diallyl malonate borate salt includes: placing boric acid, lithium carbonate and allyl diacid in anhydrous acetonitrile, reacting under a protective atmosphere and at a reaction temperature of 60~90℃ for 10~18h, and then obtaining the lithium diallyl malonate borate salt after cooling, filtration, washing and first drying treatment.

4. The porosilicate single-ion conductor polymer electrolyte containing POSS according to claim 1, characterized in that, The specific amounts of each substance, in parts by mass, are as follows: The poly(vinylidene fluoride-hexafluoropropylene): 10-25 parts; The polyethylene glycol diacrylate: 10-45 parts; The substance containing four double bond functional groups: 10-35 parts; The borate ester single-ion conductor monomer: 10-35 parts; The cage-like polysilsesquioxane containing double bonds: no more than 15 parts; The photoinitiator: no more than 0.04 parts; The thermal initiator: no more than 0.06 parts.

5. The porosilicate single-ion conductor polymer electrolyte containing POSS according to claim 4, characterized in that, The substance containing four double bond functional groups is selected from pentaerythritol tetra(thioglycolic acid) ester or pentaerythritol tetramethacrylate; the photoinitiator is selected from benzoin diethyl ether; and the thermal initiator is selected from azobisisobutyronitrile.

6. The porosilicate single-ion conductor polymer electrolyte containing POSS according to claim 1, characterized in that, The solvent solution is a mixture of two of N,N-dimethylformamide, acetonitrile, or isopropanol.

7. The porosilicate single-ion conductor polymer electrolyte containing POSS according to claim 1, characterized in that, The photo-initiated curing treatment is a UV irradiation treatment using 365nm UV light for 15–45 minutes; the solvent removal treatment, the thermal initiation curing treatment, and the second drying treatment are all performed under vacuum and 60°C conditions for 6–24 hours; the washing treatment uses anhydrous ethanol; and the second drying treatment lasts for 12 hours.

8. A method for preparing a borosilicate ester single-ion conductor polymer gel electrolyte membrane containing POSS, characterized in that, The borosilicate single-ion conductor polymer electrolyte containing POSS according to any one of claims 1-7 is immersed in an electrolyte solution to form a gel electrolyte membrane, wherein the electrolyte solution is a solution containing one or both of ethylene carbonate and dimethyl carbonate.

9. A borosilicate single-ion conductor polymer gel electrolyte membrane containing POSS, characterized in that, The POSS-containing borate ester single-ion conductor polymer gel electrolyte membrane is The product prepared according to the method of claim 8 has a lithium-ion transference number of more than 0.7 and an electrochemical window of more than 5.0.

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