Electrolyte membrane containing gel polymer and preparation method and application thereof

Abstract

The invention provides an electrolyte membrane containing a gel polymer as well as a preparation method and application of the electrolyte membrane. The electrolyte membrane comprises a fiber membrane and a gel polymer, wherein the raw materials of the gel polymer comprise a cyano polysiloxane polymer, a carbonate electrolyte and a photoinitiator; the gel polymer is obtained by carrying out light curing treatment on raw materials of the gel polymer. The high-porosity PAN cross-linked network is adopted for preparing the fiber membrane, the strong liquid absorption capacity of the fiber membrane and efficient transportation of lithium ions are guaranteed, meanwhile, the overall mechanical strength of the gel electrolyte membrane is remarkably improved through the high-strength PAN fiber membrane, and reliable guarantee is provided for application of the gel electrolyte membrane in the fields of lithium ion batteries and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium metal battery electrolytes, and in particular to an electrolyte containing a gel polymer, and a preparation method and application thereof. Background Art

[0002] Lithium metal batteries have advantages such as high energy density, long cycle life, and rapid charge and discharge, and have broad application prospects in the market. Traditional lithium metal batteries use liquid electrolytes. However, the inherent flammability and poor cycle performance of liquid electrolytes have hindered their further application. Polymer gel electrolytes, as a potential alternative to liquid electrolytes, have shown certain potential in improving battery safety. This type of electrolyte not only achieves high ionic conductivity but also forms good interfacial contact with the electrodes, thereby optimizing the electrochemical performance of the battery. However, when the polymer matrix is plasticized by organic solvents, the mechanical strength tends to decrease significantly, which restricts its further application in battery systems. In addition, among the typical polymer matrices used in gel electrolytes, the high crystallinity of PEO and PVDF severely limits the ion transfer efficiency. The glass transition temperatures of PAN and PMMA are both around 100°C, which limits the mobility of polymer chains in low-temperature environments and seriously affects the low-temperature performance of the electrolyte. Summary of the Invention

[0003] In view of the deficiencies in the prior art, the present invention provides the following technical solutions:

[0004] An electrolyte membrane comprises a fiber membrane and a gel polymer, wherein the raw materials of the gel polymer comprise a cyanopolysiloxane polymer, a carbonate electrolyte and a photoinitiator.

[0005] According to an embodiment of the present invention, the gel polymer is obtained by subjecting the raw material of the gel polymer to a photocuring treatment.

[0006] According to an embodiment of the present invention, the gel polymer is uniformly distributed on the fiber membrane.

[0007] According to an embodiment of the present invention, the fiber membrane is prepared by electrospinning a spinning matrix. Preferably, the spinning matrix is selected from at least one of polyacrylonitrile (PAN), glass (SiO2) fiber membrane, polyvinylidene fluoride (PVDF) fiber membrane, polyimide (PI) fiber membrane, cellulose fiber membrane, polyethylene oxide (PEO) fiber membrane, PVDF / SiO2 composite fiber membrane, and PAN / Al2O3 composite fiber membrane.

[0008] According to an embodiment of the present invention, the thickness of the electrolyte membrane is 20-200 μm.

[0009] The present invention also provides a method for preparing the above electrolyte membrane, which specifically comprises the following steps:

[0010] S1) Preparation of cyanopolysiloxane polymer;

[0011] S2) preparing fiber membrane by electrospinning;

[0012] S3) under inert gas protection, dissolving the cyanopolysiloxane polymer in a carbonate electrolyte, and adding a photoinitiator thereto to obtain a precursor solution;

[0013] S4) Under the protection of inert gas, the precursor solution in step S3) is injected into the fiber membrane in step S2), and after the fiber membrane is fully infiltrated, a photocuring treatment is performed under ultraviolet light to obtain the electrolyte membrane.

[0014] According to an embodiment of the present invention, in step S1), the cyanopolysiloxane polymer is prepared by the following method: using a cyclosiloxane compound and a methoxysilane compound represented by Formula 1 as raw materials, performing a polymerization reaction in the presence of a catalyst, and adding a disiloxane compound as a capping agent to prepare the cyanopolysiloxane polymer.

[0015]

[0016] Wherein, a is selected from 3, 4; -Si-O- forms a silicon-oxygen ring structure.

[0017] According to an embodiment of the present invention, the cyclosiloxane compound is selected from the compound of Formula 1-1 and / or the compound of Formula 1-2.

[0018]

[0019] According to a preferred embodiment of the present invention, the cyclosiloxane compound is selected from a mixture of a compound of Formula 1-1 and a compound of Formula 1-2, wherein the mass ratio of the compound of Formula 1-2 to the compound of Formula 1-1 is 1:(0-100), for example, 1:1.

[0020] According to an embodiment of the present invention, the methoxysilane compound is, for example, selected from the compound represented by Formula 2.

[0021]

[0022] Each R1 is the same or different and is independently selected from C 1-6 Alkyl, C 6-12 Aryl-substituted C 1-6 Alkyl, C 6-12 Aryl, at least one C 1-6 Alkyl substituted C 6-12 aryl;

[0023] R2 is selected from at least one of the following groups: 1-6 Alkyl-acrylate, -C 1-6 Alkyl-methacrylate or -OC 1-6 Alkyl-C 2-4 Epoxyalkyl.

[0024] Preferably, the methoxysilane compound is, for example, 3-(methacryloyloxy)propylmethyldimethoxysilane (KH571), and has the following structural formula.

[0025]

[0026] Preferably, the disiloxane compound is selected from the compound shown in Formula 3.

[0027]

[0028] Each R3 is the same or different and is independently selected from methyl, ethyl, -(CH2)3OC(=O)C(CH3)=CH2 (methacrylate), -(CH2)3OC(=O)CH=CH2 (acrylate) or -OCH2(CHCH2O), provided that at least one of the R3 groups at both ends of the polymer in Formula 3 is -(CH2)3OC=O)C(CH3)=CH2, -(CH2)3OC(=O)CH=CH2 or -OCH2(CHCH2O).

[0029] Preferably, the disiloxane compound is, for example, bis-3-methylacryloxypropylated tetramethyldisiloxane, and has the following structural formula.

[0030]

[0031] According to an embodiment of the present invention, the mass ratio of the cyclosiloxane compound to the methoxysilane compound is 50:(0-3), preferably 50:(0.3-1), for example 50:0.5.

[0032] According to an embodiment of the present invention, the catalyst is selected from a cationic catalyst or an anionic catalyst. Preferably, the cationic catalyst is selected from at least one or more of concentrated H2SO4, HClO4, bis(trifluoromethylsulfonyl)imide, trifluoromethylsulfonic acid, and Lewis acid. Preferably, the anionic catalyst is selected from at least one or more of tetramethylammonium hydroxide, KOH, NaOH, lithium hydroxide, tetraethylammonium hydroxide, tetrabutylphosphine hydroxide, n-butyllithium, potassium tert-butoxide, lithium siliconate, potassium siliconate, diethylamine, and benzyltrimethylammonium bis(catechol)phenylsilanol salt.

[0033] According to an embodiment of the present invention, the amount of the catalyst is 1‰-5‰.

[0034] According to an embodiment of the present invention, the polymerization reaction conditions are: reaction at 50° C. or above for at least 12 hours, for example, reaction at 50° C. for 24 hours under a nitrogen atmosphere.

[0035] Illustratively, the cyanopolysiloxane polymer has a structure as shown in Formula 4, wherein R1, R2, and R3 have the meanings as described above; b and c are the same or different and are independently selected from integers of 0-1000 (for example, 10, 100, 500); b+c is any integer greater than 0 and less than 1000.

[0036]

[0037] Preferably, the cyanopolysiloxane polymer represented by Formula 4 is prepared by a simple one-pot reaction using a cyclosiloxane compound represented by Formula 1 and a methoxysilane compound represented by Formula 2 as raw materials, and a disiloxane compound represented by Formula 3 as a capping agent. Furthermore, the mass ratio of the cyclosiloxane compound represented by Formula 1 to the methoxysilane compound represented by Formula 2 is 50:(0-3), preferably 50:(0.3-1).

[0038] Illustratively, the cyanopolysiloxane polymer has a structure as shown in the following formula 4-1.

[0039]

[0040] According to an embodiment of the present invention, in step S2), preparing the fiber membrane by electrospinning specifically includes: mixing a spinning matrix and a solvent to prepare a spinning precursor liquid, and electrospinning the spinning precursor liquid to obtain the fiber membrane.

[0041] Preferably, the mass fraction of the spinning matrix in the spinning precursor liquid is 1-20 wt.%, for example, 10 wt.%.

[0042] Preferably, the solvent is selected from at least one of dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).

[0043] Preferably, the electrospinning conditions can be selected from those known in the art, for example, including: an applied voltage of 15 to 22 kV, a distance from the syringe needle to the receiver of 15 to 20 cm, and a flow rate of 0.5 to 1.0 mL / h.

[0044] According to an embodiment of the present invention, in step S3), the carbonate electrolyte includes a lithium salt and a carbonate solvent; preferably, the lithium salt is selected from LiPF6; preferably, the carbonate solvent is selected from known carbonate solvents, exemplarily selected from at least one of EC, PC, DMC, EMC and DEC. Exemplarily, the carbonate electrolyte includes 1 mol / L LiPF6 and a mixed carbonate solvent, and the mixed carbonate solvent is selected from at least one of the following solvent combinations: EC, DMC and DEC, and the volume ratio thereof is 1:1:1 vol%; EC and EMC, the volume ratio is 3:7 (vol%); EC, DEC and PC, the volume ratio is 4:3:3 (vol%); DMC and DEC, the volume ratio is 6:4 (vol%); EC, DMC and EMC, the volume ratio is 1:1:3 (vol%); EC, DMC and EMC, the volume ratio is 3:3:4 (vol%); EC, PC and EMC, the volume ratio is 3:3:4 (vol%).

[0045] According to an embodiment of the present invention, in step S3), the mass ratio of the cyanopolysiloxane to the carbonate electrolyte is 1:0.05-5, for example, 1:0.1, 1:1, 1:2, 1:3, or 1:4.

[0046] According to an embodiment of the present invention, in steps S3) and S4), the inert atmosphere is, for example, selected from argon, wherein H2O < 0.1 ppm, O2 < 0.1 ppm.

[0047] According to an embodiment of the present invention, in step S3), the photoinitiator is selected from at least one or more of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO photoinitiator), 1-hydroxy-cyclohexyl-phenyl ketone (184 photoinitiator), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173 photoinitiator), 2-isopropylthioxanthone (2,4 isomer mixture) (ITX photoinitiator), ethyl 2,4,6-trimethylbenzoylphosphonate (TPO photoinitiator), 2-methyl-1-[4-methylthiophenyl]-2-morpholinyl-1-propanone (907 photoinitiator), methyl o-benzoylbenzoate (OMBB photoinitiator), 2,2-dimethoxy-2-phenylethanone (BDK photoinitiator) or 4-dimethylamino-ethyl benzoate (ED photoinitiator).

[0048] According to an embodiment of the present invention, the amount of the photoinitiator is 0.05wt.% to 10wt.% of the total mass of the precursor solution, for example, 0.1wt.%, 1wt.%, 2wt.%, 3wt.%, 4wt.%, 5wt.%, 6wt.%, 7wt.%, 8wt.%, 9wt.%.

[0049] According to an embodiment of the present invention, the light curing time is 0.2 to 5 minutes.

[0050] The present invention also provides application of the electrolyte membrane in lithium ion batteries.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. This invention utilizes an electrospun PAN fiber membrane as the supporting matrix, a polysiloxane rich in polar cyano (-CN) groups as the polymer backbone, and the introduction of a carbonate plasticizer to optimize ion transport performance and ensure electrochemical stability. This invention utilizes a high-porosity PAN cross-linked network to prepare the fiber membrane, ensuring not only strong liquid absorption capacity and efficient lithium ion transport, but also the high strength of the PAN fiber membrane significantly enhances the overall mechanical strength of the gel electrolyte membrane, providing reliable support for its application in lithium-ion batteries and other fields.

[0053] 2. This invention uses carbonate as a plasticizer, whose high dielectric constant significantly improves the electrolyte's ionic conductivity. Furthermore, the use of polysiloxane, a flexible and polar group-rich polysiloxane with a wide temperature range, as the gel electrolyte matrix effectively promotes efficient lithium ion transport across a wide temperature range.

[0054] Definitions and Explanations of Terms

[0055] The term "C 1-6 “Alkyl” is understood as meaning a linear or branched, saturated, monovalent hydrocarbon radical having 1, 2, 3, 4, 5 or 6 carbon atoms. The alkyl radical is, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl, etc. or isomers thereof. In particular, the radical has 1, 2 or 3 carbon atoms (“C 1-3 "alkyl"), for example methyl, ethyl, n-propyl or isopropyl.

[0056] The term "C 2-4 "Oxyalkyl" means a saturated monovalent monocyclic hydrocarbon ring containing 1 or 2 O atoms and 2 to 4 carbon atoms. 2-4 Examples of the alkylene oxide group include, but are not limited to, ethylene oxide, propylene oxide, or butylene oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 . Change of ionic conductivity of the polymer electrolyte of Example 2 with temperature.

[0058] Figure 2 .Stress-strain curve of the polymer electrolyte of Example 2.

[0059] Figure 3 .Lithium ion migration number test of Example 2.

[0060] Figure 4 .Linear sweep voltammetry curve of the polymer electrolyte of Example 2.

[0061] Figure 5 .Linear sweep voltammetry curve of the polymer electrolyte of Example 4. DETAILED DESCRIPTION

[0062] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0063] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0064] Example 1

[0065] Preparation of gel polymer electrolyte

[0066] The specific preparation process for cyanopolysiloxane is as follows: 2000g of methylcyanopropylcyclosiloxane (specifically, a mixture of the compound of Formula 1-2 and the compound of Formula 1-1, in a mass ratio of 1:1), 11.2g of bis-3-methacryloxypropylated tetramethyldisiloxane, and an appropriate amount of acid catalyst (specifically, 2‰ trifluoromethylsulfonic acid) are added to a 5000mL glass reactor equipped with a mechanical stirrer. The resulting mixture is reacted at 50°C under a nitrogen atmosphere for 24 hours. The reaction is terminated by adding bis-3-methacryloxypropylated tetramethyldisiloxane. After the reaction is complete, the mixture is washed with deionized water and ethanol, and finally vacuum-dried at 80°C for 24 hours to obtain a transparent viscous liquid, which is the cyanopolysiloxane polymer. Its structure is shown in Formula 4-1, where b is 607 and c is 0.

[0067] PAN membranes were prepared by electrospinning: 10 wt.% PAN was dissolved in DMF and stirred at 25°C for 24 h to obtain a transparent precursor solution. The precursor solution was then transferred to a 5 mL syringe equipped with a stainless steel needle. The electrospinning process was controlled at an ambient temperature of 25°C, a humidity of 50% to 60%, an applied voltage of 20 kV, a distance from the syringe needle to the receiving roller of 15 cm, and a solution propulsion speed of 0.1 mm / min. -1 After spinning, the resulting fiber membrane was dried in a vacuum oven at 60°C for 24 hours, then cut into discs with a thickness of 110 μm and a diameter of 1.9 cm and stored in a glove box.

[0068] A gel polymer electrolyte membrane was prepared using a solution impregnation-photocuring method. The specific steps are as follows: In an argon glove box (H2O <0.1ppm, O2 <0.1ppm), 5g of cyanopolysiloxane polymer was dissolved in 15g of a 1M LiPF6 electrolyte solution containing EC:DMC:DEC = 1:1:1 vol%. 1wt% of a photoinitiator was then added to the solution, and magnetic stirring was performed at 25°C for 12 hours to form a uniform, transparent precursor solution. The precursor solution was then injected into a PAN fiber membrane. After the solution fully infiltrated the fiber matrix, it was photocured under UV light for 1 minute, resulting in a gel polymer electrolyte membrane with a uniform thickness of 120μm and a dense structure.

[0069] Example 2

[0070] Preparation of gel polymer electrolyte

[0071] The specific preparation process for cyanopolysiloxane is as follows: 2000g of methylcyanopropylcyclosiloxane (specifically, a mixture of the compound of Formula 1-2 and the compound of Formula 1-1, in a mass ratio of 1:1), 18g of KH571, 10g of bis-3-methacryloxypropylated tetramethyldisiloxane, and 2‰ of trifluoromethanesulfonic acid are added to a 5000mL glass reactor equipped with a mechanical stirrer. The resulting mixture is reacted at 50°C under a nitrogen atmosphere for 24 hours. After the reaction, the mixture is washed with deionized water and ethanol, and finally vacuum-dried at 80°C for 24 hours to obtain a transparent viscous liquid, which is the cyanopolysiloxane polymer. Its structure is shown in Formula 4-1, where b is 608 and c is 3.

[0072] PAN membranes were prepared by electrospinning: 10 wt.% PAN was dissolved in DMF and stirred at 25°C for 24 h to obtain a transparent precursor solution. The precursor solution was then transferred to a 5 mL syringe equipped with a stainless steel needle. The electrospinning process was controlled at an ambient temperature of 25°C, a humidity of 50% to 60%, an applied voltage of 20 kV, a distance from the syringe needle to the receiving roller of 15 cm, and a solution propulsion speed of 0.1 mm / min. -1 After spinning, the resulting fiber membrane was dried in a vacuum oven at 60°C for 24 hours, then cut into discs with a diameter of 1.9 cm and transferred to a glove box for storage.

[0073] A gel polymer electrolyte membrane was prepared using a solution impregnation-photocuring method. The specific steps are as follows: In an argon glove box (H2O <0.1ppm, O2 <0.1ppm), 5g of cyanopolysiloxane polymer was dissolved in 15g of a 1M LiPF6 electrolyte solution containing EC:DMC:DEC = 1:1:1 vol%. 1wt% of a photoinitiator was then added to the solution, and magnetic stirring was performed at 25°C for 12 hours to form a uniform, transparent precursor solution. The precursor solution was then injected into a PAN fiber membrane. After the solution fully infiltrated the fiber matrix, it was photocured under UV light for 1 minute, resulting in a uniform, densely structured gel polymer electrolyte membrane with a thickness of 120μm.

[0074] Example 3

[0075] Preparation of gel polymer electrolyte

[0076] The specific preparation process for cyanopolysiloxane is as follows: 2000g of methylcyanopropylcyclosiloxane (specifically, a mixture of the compound of Formula 1-2 and the compound of Formula 1-1, in a mass ratio of 1:1), 24g of KH571, 10g of bis-3-methacryloxypropylated tetramethyldisiloxane, and 2‰ of trifluoromethylsulfonic acid are added to a 5000mL glass reactor equipped with a mechanical stirrer. The resulting mixture is reacted at 50°C under a nitrogen atmosphere for 24 hours. After the reaction, the mixture is washed with deionized water and ethanol, and finally vacuum-dried at 80°C for 24 hours to obtain a transparent viscous liquid, which is the cyanopolysiloxane polymer. Its structure is shown in Formula 4-1, where b is 608 and c is 4.

[0077] PAN membranes were prepared by electrospinning: 10 wt.% PAN was dissolved in DMF and stirred at 25°C for 24 h to obtain a transparent precursor solution. The precursor solution was then transferred to a 5 mL syringe equipped with a stainless steel needle. The electrospinning process was controlled at an ambient temperature of 25°C, a humidity of 50% to 60%, an applied voltage of 20 kV, a distance from the syringe needle to the receiving roller of 15 cm, and a solution propulsion speed of 0.1 mm / min. -1 After spinning, the resulting fiber membrane was dried in a vacuum oven at 60°C for 24 hours, then cut into discs with a diameter of 1.9 cm and transferred to a glove box for storage.

[0078] A gel polymer electrolyte membrane was prepared using a solution impregnation-photocuring method. The specific steps are as follows: In an argon glove box (H2O <0.1ppm, O2 <0.1ppm), 5g of cyanopolysiloxane polymer was dissolved in 15g of a 1M LiPF6 electrolyte solution containing EC:DMC:DEC = 1:1:1 vol%. 1wt% of a photoinitiator was then added to the solution, and magnetic stirring was performed at 25°C for 12 hours to form a uniform, transparent precursor solution. The precursor solution was then injected into a PAN fiber membrane. After the solution fully infiltrated the fiber matrix, it was photocured under UV light for 1 minute, resulting in a uniform, densely structured gel polymer electrolyte membrane with a thickness of 120μm.

[0079] Example 4

[0080] Preparation of gel polymer electrolyte

[0081] The preparation process of cyanopolysiloxane is the same as that in Example 2.

[0082] PAN membranes were prepared by electrospinning: 10 wt.% PAN was dissolved in DMF and stirred at 25°C for 24 h to obtain a transparent precursor solution. The precursor solution was then transferred to a 5 mL syringe equipped with a stainless steel needle. The electrospinning process was controlled at an ambient temperature of 25°C, a humidity of 50% to 60%, an applied voltage of 20 kV, a distance from the syringe needle to the receiving roller of 15 cm, and a solution propulsion speed of 0.1 mm / min. -1 After spinning, the resulting fiber membrane was dried in a vacuum oven at 60°C for 24 hours, then cut into discs with a diameter of 1.9 cm and transferred to a glove box for storage.

[0083] A gel polymer electrolyte membrane was prepared using a solution impregnation-photocuring method. The specific steps are as follows: In an argon glove box (H2O <0.1ppm, O2 <0.1ppm), 5g of cyanopolysiloxane polymer was dissolved in 20g of a 1M LiPF6 electrolyte solution containing EC:DMC:DEC (1:1:1 vol%). 1wt% of a photoinitiator was then added to the solution, and magnetic stirring was performed at 25°C for 12 hours to form a uniform, transparent precursor solution. The precursor solution was then injected into a PAN fiber membrane. After the solution fully infiltrated the fiber matrix, it was photocured under UV light for 1 minute, resulting in a gel polymer electrolyte membrane with a uniform thickness of 120μm and a dense structure.

[0084] Example 5

[0085] Preparation of gel polymer electrolyte

[0086] The preparation process of cyanopolysiloxane is the same as that in Example 2.

[0087] PAN membranes were prepared by electrospinning: 10 wt.% PAN was dissolved in DMF and stirred at 25°C for 24 h to obtain a transparent precursor solution. The precursor solution was then transferred to a 5 mL syringe equipped with a stainless steel needle. The electrospinning process was controlled at an ambient temperature of 25°C, a humidity of 50% to 60%, an applied voltage of 20 kV, a distance from the syringe needle to the receiving roller of 15 cm, and a solution propulsion speed of 0.1 mm / min. -1 After spinning, the resulting fiber membrane was dried in a vacuum oven at 60°C for 24 hours, then cut into discs with a diameter of 1.9 cm and transferred to a glove box for storage.

[0088] A gel polymer electrolyte membrane was prepared using a solution impregnation-photocuring method. The specific steps are as follows: In an argon glove box (H2O <0.1ppm, O2 <0.1ppm), 5g of cyanopolysiloxane polymer was dissolved in 12.5g of a 1M LiPF6 electrolyte solution containing EC:DMC:DEC = 1:1:1 vol%. 1wt% of a photoinitiator was then added to the solution, and magnetic stirring was performed at 25°C for 12 hours to form a uniform, transparent precursor solution. The precursor solution was then injected into a PAN fiber membrane. After the solution fully infiltrated the fiber matrix, it was photocured under UV light for 1 minute, resulting in a gel polymer electrolyte membrane with a uniform thickness of 120μm and a dense structure.

[0089] Test Example 1

[0090] The polymer gel electrolyte membrane of the above embodiment was tested as follows:

[0091] (1) Ionic conductivity: The electrolyte membrane was sandwiched between two stainless steel electrodes (SS) to assemble into an SS / electrolyte / SS battery. The AC impedance spectrum of the blocked electrode was measured on an AutoLab 302N electrochemical workstation, and the electrolyte impedance R was recorded. b The tested frequency range is 10 6 ~10 -1 Hz, the test temperature is -30 ~ 70 ° C. The ionic conductivity (σ) of the electrolyte is calculated by the following formula:

[0092] σ=L / R b ×S

[0093] L is the thickness of the electrolyte membrane; R b is the impedance of the electrolyte membrane; S is the contact area between the electrolyte membrane and the stainless steel electrode.

[0094] (2) Lithium ion transference number: The lithium ion transference number of the electrolyte is tested using the DC polarization method combined with the AC impedance method. The electrolyte membrane is sandwiched between two pieces of metallic lithium to assemble a Li / electrolyte / Li battery.

[0095] First, in the frequency range 10 6 ~10 -1 The initial impedance of the electrolyte was tested within Hz. Subsequently, a 10mV DC voltage was applied to both sides of the electrolyte for constant voltage polarization, and the current variation curve with time was recorded. After the system current reached a stable state, the electrochemical impedance of the electrolyte was measured again. Finally, according to

[0096] The Bruce-Vincent-Evans formula can be used to calculate the lithium ion migration number:

[0097]

[0098] Where ΔV is the polarization voltage; I0 and I SS is the initial and steady-state current; R0 and R SS is the electrochemical impedance before and after polarization.

[0099] (3) Electrochemical window test:

[0100] Linear sweep voltammetry (LSV) was used to test the electrochemical window of the electrolyte membrane. The electrolyte was sandwiched between stainless steel and metallic lithium to assemble a Li / electrolyte / SS battery. -1 Record the change of current with voltage.

[0101] The test results are as follows:

[0102] Figure 1 The ionic conductivity of the polymer electrolyte of Example 2 changes with temperature.

[0103] Figure 2 This is the stress-strain curve of the polymer electrolyte of Example 2.

[0104] Figure 3 This is the lithium ion migration number test of Example 2.

[0105] Figure 4 This is the linear sweep voltammetry curve of the polymer electrolyte of Example 2.

[0106] Figure 5 This is the linear sweep voltammetry curve of the polymer electrolyte of Example 4.

[0107]

[0108] In Examples 1-3, increasing the amount of KH571 added resulted in a slight increase in the strength of the resulting product (Formula 4-1) after curing, but no significant improvement in strength was observed after composite with a PAN support membrane. In Examples 4-5, varying the mass fraction of the electrolyte, as the mass fraction increased, the electrolyte ion conductivity increased, the lithium ion transference number decreased slightly, and the stable voltage range remained unchanged.

[0109] The above describes exemplary embodiments of the present invention. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electrolyte membrane, characterized in that The electrolyte membrane comprises a fiber membrane and a gel polymer, and the raw materials of the gel polymer comprise a cyanopolysiloxane polymer, a carbonate electrolyte and a photoinitiator.

2. The electrolyte membrane according to claim 1, wherein The gel polymer is obtained by subjecting the raw material of the gel polymer to a light-curing treatment; The gel polymer is evenly distributed on the fiber membrane; The fiber membrane is prepared by electrospinning a spinning matrix; the spinning matrix is selected from at least one of polyacrylonitrile, glass fiber membrane, polyvinylidene fluoride fiber membrane, polyimide fiber membrane, cellulose fiber membrane, polyethylene oxide fiber membrane, PVDF / SiO2 composite fiber membrane, and PAN / Al2O3 composite fiber membrane; The thickness of the electrolyte membrane is 20-200 μm.

3. The method for preparing an electrolyte membrane according to claim 1 or 2, characterized in that: The preparation method specifically comprises the following steps: S1) Preparation of cyanopolysiloxane polymer; S2) preparing fiber membrane by electrospinning; S3) under inert gas protection, dissolving the cyanopolysiloxane polymer in a carbonate electrolyte, and adding a photoinitiator thereto to obtain a precursor solution; S4) Under the protection of inert gas, the precursor solution in step S3) is injected into the fiber membrane in step S2), and after the fiber membrane is fully infiltrated, a photocuring treatment is performed under ultraviolet light to obtain the electrolyte membrane.

4. The preparation method according to claim 3, characterized in that In step S1), the cyanopolysiloxane polymer is prepared by the following method: using a cyclosiloxane compound and a methoxysilane compound represented by formula 1 as raw materials, performing a polymerization reaction in the presence of a catalyst, and adding a disiloxane compound as a capping agent; Wherein, a is selected from 3, 4; -Si-O- forms a silicon-oxygen ring structure.

5. The preparation method according to claim 3 or 4, characterized in that The cyclosiloxane compound is selected from the compound of formula 1-1 and / or the compound of formula 1-2; The cyclosiloxane compound is selected from a mixture of a compound of Formula 1-1 and a compound of Formula 1-2, wherein the mass ratio of the compound of Formula 1-2 to the compound of Formula 1-1 is 1:(0-100).

6. The preparation method according to any one of claims 3 to 5, characterized in that The methoxysilane compound is selected from the compound shown in Formula 2; Each R1 is the same or different and is independently selected from C 1-6 Alkyl, C 6-12 Aryl-substituted C 1-6 Alkyl, C 6-12 Aryl, at least one C 1-6 Alkyl substituted C 6-12 aryl; R2 is selected from at least one of the following groups: 1-6 Alkyl-acrylate, -C 1-6 Alkyl-methacrylate or -OC 1-6 Alkyl-C 2-4 Epoxyalkyl; The disiloxane compound is selected from the compound shown in Formula 3; Each R3 is the same or different and is independently selected from methyl, ethyl, -(CH2)3OC(=O)C(CH3)=CH2 (methacrylate), -(CH2)3OC(=O)CH=CH2 (acrylate) or -OCH2(CHCH2O), provided that at least one of the R3 groups at both ends of the polymer in Formula 3 is -(CH2)3OC=O)C(CH3)=CH2, -(CH2)3OC(=O)CH=CH2 or -OCH2(CHCH2O).

7. The preparation method according to any one of claims 3 to 6, characterized in that The mass ratio of the cyclosiloxane compound to the methoxysilane compound is 50:(0-3); The catalyst is selected from a cationic catalyst or an anionic catalyst; The amount of the catalyst is 1‰-5‰; The polymerization reaction conditions are: reaction at 50° C. or above for at least 12 hours.

8. The preparation method according to any one of claims 3 to 7, characterized in that In step S2), the electrospinning method for preparing the fiber membrane specifically includes: mixing a spinning matrix and a solvent to prepare a spinning precursor liquid, and electrospinning the spinning precursor liquid to obtain a fiber membrane; In step S3), the carbonate electrolyte includes a lithium salt and a carbonate solvent; In step S3), the mass ratio of the cyanopolysiloxane to the carbonate electrolyte is 1:0.05-5.

9. The preparation method according to any one of claims 3 to 8, characterized in that In step S3), the photoinitiator is selected from at least one or more of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxy-cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-isopropylthioxanthone (2,4 isomer mixture), ethyl 2,4,6-trimethylbenzoylphosphonate, 2-methyl-1-[4-methylthiophenyl]-2-morpholinyl-1-propanone, methyl o-benzoylbenzoate, 2,2-dimethoxy-2-phenylethanone or 4-dimethylamino-ethyl benzoate; The amount of the photoinitiator is 0.05 wt.% to 10 wt.% of the total mass of the precursor solution; The light curing time is 0.2 to 5 minutes.

10. Use of the electrolyte membrane according to claim 1 or 2 in a lithium ion battery.

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