A cross-linked organic-inorganic nanomaterial modified solid-state polymer electrolyte and a preparation method thereof

Abstract

The application belongs to the field of lithium ion batteries, and particularly relates to a crosslinked organic-inorganic composite nanomaterial modified solid-state polymer electrolyte and a preparation method thereof. The electrolyte composition comprises a polymer matrix, a lithium salt and super-crosslinked organic-inorganic composite fillers. The super-crosslinked organic-inorganic composite fillers are super-crosslinked nanoparticles with a core-shell structure, which are obtained by a Friedel-Crafts reaction using an organic-inorganic copolymer as a reaction monomer. The electrolyte is obtained by uniformly stirring the super-crosslinked organic-inorganic composite fillers, the polymer matrix and the lithium salt in a solvent, and then casting and drying under anhydrous and oxygen-free environment. The solid-state polymer electrolyte has high ionic conductivity and other excellent electrochemical properties, and can be used in a wide temperature range.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion batteries, specifically relating to a cross-linked organic-inorganic composite nanomaterial modified solid polymer electrolyte and its preparation method. Background Technology

[0002] Traditional lithium-ion batteries mainly consist of four key components: a positive electrode, a negative electrode, a separator, and a liquid electrolyte. Commonly used separator materials are microporous membranes made of polyolefins such as PE and PP. However, these membranes have poor dimensional stability at high temperatures and are prone to thermal shrinkage, leading to internal short circuits. The liquid electrolyte system mainly consists of lithium salts and carbonate-based organic solvents. The large volume of flowing, flammable liquid electrolyte poses a leakage risk and can easily cause fires and explosions when subjected to impacts or mechanical abuse. To address these issues, some studies have modified the polyolefin separator by coating it with a high-temperature resistant ceramic coating or by adding flame retardants to the electrolyte. While these methods do improve battery safety to some extent, they often have limitations. The fundamental solution is to use a solid-state electrolyte instead of the separator / liquid electrolyte system.

[0003] Solid electrolytes are mainly divided into two categories: inorganic solid electrolytes (SSEs) and solid polymer electrolytes (SPEs). Inorganic solid electrolytes generally have high ionic conductivity (up to 10 at room temperature). -3 S·cm -1 However, it has high interfacial impedance and poor interfacial compatibility with electrode materials. Solid polymer electrolytes (SPEs) are basically composed of a polymer matrix and lithium salts, with PEO being the most commonly used matrix material. PEO-based solid polymer electrolytes have sufficient flexibility and good interfacial compatibility, but their high crystallinity results in excessively low room-temperature ionic conductivity (10⁻⁶ Ω·cm). -8 -10 -6 S·cm -1 Modification methods typically employ inorganic filler doping, polymer blending, and crosslinking. However, the introduction of inorganic fillers can easily lead to uneven distribution within the polymer matrix, simple blending can easily result in deterioration of mechanical properties, and traditional crosslinking methods may leave behind a large amount of monomers, initiators, etc., thereby affecting the performance of solid polymer electrolytes. Summary of the Invention

[0004] To address the shortcomings caused by the introduction of inorganic fillers, this invention provides a cross-linked organic-inorganic composite nanomaterial-modified solid polymer electrolyte and its preparation method. The resulting solid polymer electrolyte exhibits high ionic conductivity and other excellent electrochemical properties.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows:

[0006] Firstly, a cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte is provided, the composition of which includes: a polymer matrix, a lithium salt and a super-cross-linked organic-inorganic composite filler, wherein the super-cross-linked organic-inorganic composite filler is a core-shell structured super-cross-linked nanoparticle obtained by Friedel-Crafts reaction with organic-inorganic copolymer as the reactive monomer.

[0007] Furthermore, the inorganic component in the organic-inorganic copolymer is an inorganic filler modified with a double-bonded silane coupling agent, and the organic component is a random copolymer containing a benzene ring.

[0008] Furthermore, the organic-inorganic copolymer is prepared by the following method: inorganic filler, a first reactive monomer, and a second reactive monomer are subjected to pre-crosslinking and free radical emulsion polymerization under the action of a second crosslinking agent, an initiator, and an emulsifier to obtain the organic-inorganic copolymer; wherein, the first reactive monomer is styrene or a styrene derivative without strong electron-withdrawing groups, and the second reactive monomer is selected from at least one of methyl methacrylate, methyl acrylate, vinyl acetate, polyethylene glycol monomethyl ether methacrylate, or acrylonitrile; the inorganic filler is at least one of silane coupling agent modified SiO2, TiO2, or ZnO2.

[0009] Furthermore, the inorganic filler is SiO2 modified with silane coupling agent KH-570.

[0010] Furthermore, the second crosslinking agent is o-divinylbenzene, m-divinylbenzene, or p-divinylbenzene.

[0011] Furthermore, the initiator is at least one of potassium persulfate, ammonium persulfate, or sodium persulfate.

[0012] Furthermore, the emulsifier is at least one of sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate, or sodium octadecylbenzenesulfonate.

[0013] In the above electrolyte, the raw materials for the hypercrosslinked organic-inorganic composite filler include: organic-inorganic copolymer, catalyst and first crosslinking agent.

[0014] Furthermore, the hypercrosslinked organic-inorganic composite filler is prepared by the following method: under anhydrous and oxygen-free conditions, an organic-inorganic copolymer is used as the reactive monomer and added to a Friedel-Crafts reaction system containing a catalyst, a first crosslinking agent, and a second solvent, and reacted at a temperature of 25–80°C to obtain hypercrosslinked organic-inorganic nanoparticles.

[0015] Furthermore, the catalyst is selected from at least one of FeCl3, AlCl3, ZnCl2 or SnCl4.

[0016] Furthermore, the first crosslinking agent is selected from at least one of dimethoxymethane or ethylene glycol dimethyl ether.

[0017] Furthermore, the second solvent is at least one of 1,2-dichloroethane or dichloromethane.

[0018] Furthermore, the mass ratio of the second solvent to the organic-inorganic copolymer is 20 to 25:1, and the mass ratio of the first crosslinking agent to the organic-inorganic copolymer is 0.4 to 1.3:1.

[0019] In the above electrolyte, the mass fraction of the hypercrosslinked organic-inorganic composite filler in the electrolyte is 5-20%, and the molar ratio of the polymer matrix to the lithium salt satisfies N:Li = 10-20:1, where N is the structural unit in the polymer matrix that interacts with the lithium salt.

[0020] In the above electrolyte, the polymer matrix is ​​selected from at least one of polyethylene oxide (PEO), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride, or polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP); preferably polyethylene oxide.

[0021] In the above electrolyte, the lithium salt is selected from at least one of lithium perchlorate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, and lithium trifluoromethanesulfonate.

[0022] The present invention also provides a method for preparing any of the above-mentioned cross-linked organic-inorganic nanomaterial modified solid polymer electrolytes: under anhydrous and oxygen-free environment, the super-cross-linked organic-inorganic composite filler, polymer matrix and lithium salt are uniformly stirred in a first solvent to obtain an electrolyte solution, the solution is cast into a mold and dried to obtain a solid polymer electrolyte membrane.

[0023] Furthermore, the first solvent is selected from at least one of anhydrous acetonitrile, tetrahydrofuran, N,N-dimethylformamide, acetone, and dichloromethane.

[0024] Furthermore, the electrolyte solution after uniform stirring is ultrasonically dispersed for 3-5 minutes, allowed to stand for 20-30 minutes for degassing treatment, and then cast.

[0025] Furthermore, the drying conditions are: drying at room temperature for 6–12 hours followed by vacuum drying at 60°C for 12–24 hours.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention introduces organic-inorganic composite fillers to enhance the ionic conductivity and interfacial stability of the modified solid polymer electrolyte. Inorganic fillers, such as SiO2, act as Lewis acid-base reaction centers, promoting lithium salt dissociation. Grafting organic copolymer segments modify the matrix, resulting in uniform nanoparticle distribution. Simultaneously, the high specific surface area of ​​the hypercrosslinked structure increases the surface area for Lewis acid-base interactions, accelerating lithium-ion transport. The synergistic effect of carbonyl groups in polymers such as PMMA further facilitates lithium-ion transport. The introduction of inorganic mSiO2 promotes uniform lithium deposition and improves the interfacial stability of the lithium electrode.

[0028] This invention improves the thermal dimensional stability of solid polymer electrolytes (LIBs) by introducing a cross-linked structure. The modified LIB maintains good dimensional stability even at 260°C. This is because the network structure of organic-inorganic composite fillers (such as hypercrosslinked mSiO2-g-PMMA-co-PS organic-inorganic copolymers) requires all chemical bonds at the cross-linking sites to break before further decomposition. Otherwise, free radicals generated during decomposition will react with the polymer again. Therefore, the decomposition of cross-linking points requires higher temperatures. Furthermore, the high specific surface area of ​​the hypercrosslinked material reduces thermal resistance and aids in heat dissipation. This high thermal stability broadens the operating temperature range of LIBs and reduces the risk of battery short circuits, thus meeting the safety requirements of lithium-ion batteries operating at high temperatures.

[0029] The solid polymer electrolyte obtained by this invention can be used in: (1) common electrical appliances, such as mobile phones, computers, and cameras; (2) certain industries that require operation in high-temperature environments, such as the electric vehicle industry, underground oil extraction industry, and aerospace industry. The solid polymer electrolyte obtained by this invention can be used in a wide temperature range. Attached image description:

[0030] Figure 1 The following are the TEM characterization results of the cross-linked organic-inorganic nanomaterials in this invention:

[0031] (a) is a TEM image of SMS-1 in Embodiment 1 of the present invention;

[0032] (b) is a TEM image of SMS-2 in Embodiment 2 of the present invention;

[0033] (c) is a TEM image of SMS-3 in Embodiment 3 of the present invention;

[0034] (d) is a TEM image of HSMS-1 in Embodiment 1 of the present invention;

[0035] (e) is a TEM image of HSMS-2 in Embodiment 2 of the present invention;

[0036] (f) is a TEM image of HSMS-3 in Embodiment 3 of the present invention.

[0037] Figure 2 The nitrogen adsorption-desorption curves and pore size distribution diagrams of HSMS-2 and SMS-2 in Examples 2 and 5 of this invention are shown.

[0038] Figure 3 The following are SEM images and EDS distribution diagrams of Si element in the modified solid polymer electrolyte membrane of this invention:

[0039] Figure 3 (a) to (d) are SEM images of CSPE-mSiO2, CSPE-1, CSPE-2 and CSPE-3, respectively;

[0040] Figure 3 (e) to (h) are EDS distribution diagrams of Si elements in CSPE-mSiO2, CSPE-1, CSPE-2, and CSPE-3, respectively.

[0041] Figure 4 Images of the solid polymer electrolytes in Examples 1-6 and Example 8 after heat treatment at different temperatures.

[0042] Figure 5 Linear sweep voltammetry curves of the solid polymer electrolytes in Examples 1-3 and Example 7 are shown.

[0043] Figure 6 The lithium-ion transference number test curves are for the Li / / Li coin cells assembled with solid polymer electrolytes in Examples 9 and 2 at room temperature.

[0044] Figure 7 The test curves show the lithium stability performance of the Li / / Li coin cells assembled with solid polymer electrolytes in Examples 9 and 2 at 50°C.

[0045] Figure 8 The rate performance test curves of Li / / LiFePO4 coin cells assembled with solid polymer electrolytes in Examples 1-3 and Example 7 at 50°C are shown. Detailed Implementation

[0046] The specific embodiments of the present invention will be further described below through specific examples, but the present invention is obviously not limited to the following embodiments and there can be many variations.

[0047] Example 1

[0048] The preparation of the cross-linked organic-inorganic nanomaterial HSMS-1 modified solid polymer electrolyte includes the following steps:

[0049] 1) Synthesis of mSiO2:

[0050] 125 mL of ethanol, 10 mL of tetraethyl orthosilicate (TEOS), and 10 mL of ammonia (NH3·H2O) were added to a three-necked flask. After vigorous mechanical stirring at 25 °C for 24 h, a mixed solution of 1 mL of 3-(trimethoxysilyl)propyl acrylate (KH-570) and 6.5 mL of ethanol was added dropwise to the three-necked flask. The stirring speed was adjusted, and vigorous mechanical stirring was continued for 24 h. The mixture was then washed with methanol, centrifuged three times, and vacuum dried for 24 h to obtain mSiO2.

[0051] 2) Synthesis of organic-inorganic nanomaterial SMS-1:

[0052] Under an argon atmosphere, 0.0732 g of sodium dodecylbenzenesulfonate (SDBS) and 0.24 g of NaHCO3 were added to a three-necked flask, and 100 mL of deionized water was added to dissolve and stir. 1.2 g of mSiO2 obtained in step 1) was ultrasonically dispersed in 10 mL of ethanol for 30 min and added to the three-necked flask. The temperature was raised to 55 °C, and 0.026 mol of purified styrene, 0.019 mol of methyl methacrylate, and 0.462 g of divinylbenzene were added sequentially. Pre-emulsification was carried out at 55 °C for 1 h. 0.5 g of potassium persulfate initiator was dissolved in 2 mL of deionized water. When the temperature was raised to 85 °C, the initiator aqueous solution was added dropwise, and the reaction was allowed to proceed for 4 h. The reaction was stopped in an ice bath, and the product was obtained by centrifugation, washing, and drying, and designated as SMS-1.

[0053] 3) Synthesis of cross-linked organic-inorganic nanomaterial HSMS-1:

[0054] Add 1g of SMS-1 obtained in step 2) and 20ml of 1,2-dichloroethane (DCE) to a three-necked flask, and sonicate for 30min. Under anhydrous and oxygen-free conditions, add 2.030g of FeCl3 and 1.494ml of dimethoxymethane (FDA) sequentially to the three-necked flask, raise the temperature to 45℃, and react for 5h. Then raise the temperature to 80℃ and react for 19h. Quench the reaction with a large amount of methanol, cool, and sonicate. After filtration, wash several times with methanol at 80℃ until the filtrate is clear, and dry under vacuum at 60℃ for 24h to obtain HSMS-1.

[0055] 4) Preparation of solid polymer electrolyte CSPE-1 modified by cross-linked organic-inorganic nanomaterial HSMS-1:

[0056] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Next, 10% wt of HSMS-1 obtained in step 3) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain electrolyte CSPE-1.

[0057] Example 2

[0058] The preparation of cross-linked organic-inorganic nanomaterial HSMS-2 modified solid polymer electrolyte includes the following steps:

[0059] 1) Synthesis of mSiO2: The specific method is the same as step 1 in Example 1).

[0060] 2) Synthesis of organic-inorganic nanomaterial SMS-2:

[0061] Under an argon atmosphere, 0.0732 g of sodium dodecylbenzenesulfonate (SDBS) and 0.24 g of NaHCO3 were added to a three-necked flask, and 100 mL of deionized water was added to dissolve and stir. 1.2 g of mSiO2 obtained in step 1) was ultrasonically dispersed in 10 mL of ethanol for 30 min and added to the three-necked flask. The temperature was raised to 55 °C, and 0.017 mol of purified styrene, 0.028 mol of methyl methacrylate, and 0.465 g of divinylbenzene were added sequentially. Pre-emulsification was carried out at 55 °C for 1 h. 0.05 g of potassium persulfate initiator was dissolved in 2 mL of deionized water. When the temperature was raised to 85 °C, the initiator aqueous solution was added dropwise, and the reaction was allowed to proceed for 4 h. The reaction was stopped in an ice bath, and the product was obtained by centrifugation, washing, and drying, and designated as SMS-2.

[0062] 3) Synthesis of cross-linked organic-inorganic nanomaterial HSMS-2:

[0063] Add 1g of SMS-2 obtained in step 2) and 20ml of 1,2-dichloroethane (DCE) to a three-necked flask, and sonicate for 30min. Under anhydrous and oxygen-free conditions, add 1.363g of FeCl3 and 0.740ml of dimethoxymethane (FDA) sequentially to the three-necked flask, raise the temperature to 45℃, and react for 5h. Then raise the temperature to 80℃ and react for 19h. Quench the reaction with a large amount of methanol, cool, and sonicate. After filtration, wash several times with methanol at 80℃ until the filtrate is clear, and dry under vacuum at 60℃ for 24h to obtain HSMS-2.

[0064] 4) Preparation of solid polymer electrolyte CSPE-2 modified by cross-linked organic-inorganic nanomaterial HSMS-2:

[0065] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Next, 10% wt of HSMS-2 obtained in step 3) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain electrolyte CSPE-2.

[0066] Example 3

[0067] The preparation of cross-linked organic-inorganic nanomaterial HSMS-3 modified solid polymer electrolyte includes the following steps:

[0068] 1) Synthesis of mSiO2: The specific method is the same as step 1 in Example 1).

[0069] 2) Synthesis of organic-inorganic nanomaterial SMS-3:

[0070] Under an argon atmosphere, 0.0732 g of sodium dodecylbenzenesulfonate (SDBS) and 0.24 g of NaHCO3 were added to a three-necked flask, and 100 mL of deionized water was added to dissolve and stir. 1.2 g of mSiO2 obtained in step 1) was ultrasonically dispersed in 10 mL of ethanol for 30 min and added to the three-necked flask. The temperature was raised to 55 °C, and 0.008 mol of purified styrene, 0.037 mol of methyl methacrylate, and 0.469 g of divinylbenzene were added sequentially. Pre-emulsification was carried out at 55 °C for 1 h. 0.05 g of potassium persulfate initiator was dissolved in 2 mL of deionized water. When the temperature was raised to 85 °C, the initiator aqueous solution was added dropwise, and the reaction was allowed to proceed for 4 h. The reaction was stopped in an ice bath, and the product was obtained by centrifugation, washing, and drying, and designated as SMS-3.

[0071] 3) Synthesis of cross-linked organic-inorganic nanomaterial HSMS-3:

[0072] Add 1g of SMS-3 obtained in step 2) and 20ml of 1,2-dichloroethane (DCE) to a three-necked flask, and sonicate for 30min. Under anhydrous and oxygen-free conditions, add 0.670g of FeCl3 and 0.438ml of dimethoxymethane (FDA) sequentially to the three-necked flask, raise the temperature to 45℃, and react for 5h. Then raise the temperature to 80℃ and react for 19h. Quench the reaction with a large amount of methanol, cool, and sonicate. After filtration, wash several times with methanol at 80℃ until the filtrate is clear, and dry under vacuum at 60℃ for 24h to obtain HSMS-3.

[0073] 4) Preparation of solid polymer electrolyte CSPE-3 modified by cross-linked organic-inorganic nanomaterial HSMS-3:

[0074] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Next, 10% wt of HSMS-3 obtained in step 3) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain electrolyte CSPE-3.

[0075] Example 4

[0076] The preparation of solid polymer electrolyte modified with organic-inorganic nanomaterial SMS-1 includes the following steps:

[0077] 1) Synthesis of mSiO2: The specific method is the same as step 1 in Example 1).

[0078] 2) Synthesis of organic-inorganic nanomaterial SMS-1: The specific method is the same as step 2 in Example 1.

[0079] 3) Preparation of solid polymer electrolyte UCSPE-1 modified with organic-inorganic nanomaterial SMS-1:

[0080] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Then, 10% wt of SMS-1 obtained in step 2) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain electrolyte UCSPE-1.

[0081] Example 5

[0082] The preparation of solid polymer electrolyte modified with organic-inorganic nanomaterial SMS-2 includes the following steps:

[0083] 1) Synthesis of mSiO2: The specific method is the same as step 1 in Example 1).

[0084] 2) Synthesis of organic-inorganic nanomaterial SMS-2: The specific method is the same as step 2 in Example 2.

[0085] 3) Preparation of solid polymer electrolyte UCSPE-2 modified by organic-inorganic nanomaterial SMS-2:

[0086] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Then, 10% wt of SMS-2 obtained in step 2) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain electrolyte UCSPE-2.

[0087] Example 6

[0088] The preparation of solid polymer electrolyte modified with organic-inorganic nanomaterials SMS-3 includes the following steps:

[0089] 1) Synthesis of mSiO2: The specific method is the same as step 1 in Example 1).

[0090] 2) Synthesis of organic-inorganic nanomaterial SMS-3: The specific method is the same as step 2 in Example 3.

[0091] 3) Preparation of solid polymer electrolyte UCSPE-2 modified by organic-inorganic nanomaterial SMS-3:

[0092] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Then, 10% wt of SMS-3 obtained in step 2) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain the electrolyte UCSPE-3.

[0093] Example 7

[0094] As a reference sample, a solid polymer electrolyte modified only with mSiO2 was prepared, including the following steps:

[0095] 1) Synthesis of mSiO2: The specific method is the same as step 1 in Example 1).

[0096] 2) Preparation of mSiO2 modified solid polymer electrolyte CSPE-mSiO2.

[0097] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Then, 10% wt of the mSiO2 obtained in step 1) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain the electrolyte CSPE-mSiO2.

[0098] Example 8

[0099] As a reference sample, an unmodified solid polymer electrolyte was prepared, including the following steps:

[0100] 1) Preparation of unmodified solid polymer electrolyte SPE-PEO:

[0101] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.361 g PEO and 0.556 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was added, and the mixture was stirred at room temperature for 96 h until it was uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain the electrolyte SPE-PEO.

[0102] Example 9

[0103] As a reference, a solid polymer electrolyte modified only with organic nanomaterials was prepared, including the following steps:

[0104] 1) Synthesis of organic nanomaterial MS-2:

[0105] Under an argon atmosphere, 100 mL of deionized water was added to a three-necked flask to dissolve the styrene, followed by the addition of 0.017 mol purified styrene, 0.028 mol methyl methacrylate, and 0.465 g divinylbenzene. The mixture was stirred and dispersed for 30 min. 0.05 g of potassium persulfate initiator was dissolved in 2 mL of deionized water, and the mixture was heated to 110 °C. The initiator solution was added dropwise, and the reaction was allowed to proceed for 4 h. The reaction was stopped in an ice bath, and the product was obtained by centrifugation, washing, and drying. The product was designated MS-2.

[0106] 2) Synthesis of cross-linked organic nanomaterial HMS-2:

[0107] Add 1g of MS-2 obtained in step 1) and 20ml of 1,2-dichloroethane (DCE) to a three-necked flask, and sonicate for 30min. Under anhydrous and oxygen-free conditions, add 2.2g of FeCl3 and 1.2ml of dimethoxymethane (FDA) sequentially to the three-necked flask, raise the temperature to 45℃, and react for 5h. Then raise the temperature to 80℃ and react for 19h. Quench the reaction with a large amount of methanol, cool, and sonicate. After filtration, wash several times with methanol at 80℃ until the filtrate is clear, and dry under vacuum at 60℃ for 24h to obtain HMS-2.

[0108] 3) Preparation of solid polymer electrolyte SPE-2 modified by cross-linked organic nanomaterial HMS-2:

[0109] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Next, 10% wt of HMS-2 obtained in step 2) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain electrolyte SPE-2.

[0110] Example 10

[0111] A solid polymer electrolyte modified with mSiO2-gP(PEGMA)-co-PS was prepared, comprising the following steps:

[0112] 1) Synthesis of the macromonomer PEGMA:

[0113] Under an anhydrous and oxygen-free atmosphere, 25 g of PEGME was added to a three-necked flask, and the mixture was evacuated three times. Then, 100 ml of DCM (SafeDry) was added, and the mixture was stirred until the PEGME dissolved. Next, 10.4 ml of TEA was added. 30 ml of DCM (SafeDry) was added to a single-necked flask, and 4.84 ml of methacryloyl chloride was added under ice bath conditions, stirring until homogeneous. Both flasks were subjected to bubbling for 30 minutes. The solution in the single-necked flask was aspirated with a long needle and slowly added dropwise to the three-necked flask under ice bath conditions. The three-necked flask was then transferred to an oil bath and reacted at 30°C for 24 hours.

[0114] 2) Synthesis of mSiO2: The specific method is the same as step 1 in Example 1).

[0115] 3) Synthesis of organic nanomaterial SPS:

[0116] Under an argon atmosphere, 3.636 g of PEGMA was added to a three-necked flask, followed by 100 mL of deionized water and heating to dissolve. Then, 1.2 g of mSiO2, 1 mL of purified styrene, and 0.62 mL of divinylbenzene were added sequentially, and the mixture was stirred and dispersed for 30 min. 0.05 g of potassium persulfate initiator was dissolved in 2 mL of deionized water, and the mixture was heated to 110 °C. The initiator solution was added dropwise, and the reaction was allowed to proceed for 4 h. The reaction was stopped in an ice bath, and the product was obtained by centrifugation, washing, and drying, and denoted as SPS.

[0117] 4) Synthesis of cross-linked organic-inorganic nanomaterials HSPS:

[0118] Add 1g of SPS obtained in step 3) and 20ml of 1,2-dichloroethane (DCE) to a three-necked flask, and sonicate for 30min. Under anhydrous and oxygen-free conditions, add 2.2g of FeCl3 and 1.2ml of dimethoxymethane (FDA) sequentially to the three-necked flask, raise the temperature to 45℃, and react for 5h. Then raise the temperature to 80℃ and react for 19h. Quench the reaction with a large amount of methanol, cool, and sonicate. After filtration, wash several times with methanol at 80℃ until the filtrate is clear, and dry under vacuum at 60℃ for 24h to obtain HSPS.

[0119] 5) Preparation of CPE modified solid polymer electrolyte using cross-linked organic nanomaterial HSPS:

[0120] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.5 ppm), 1.225 g PEO and 0.5 g LiTFSI (EO:Li = 16:1 molar ratio) were added sequentially to a 50 ml Erlenmeyer flask. A mixed solvent of 25 ml tetrahydrofuran and 5 ml anhydrous acetonitrile was then added, and the mixture was stirred at room temperature for 24 h. Next, 10% wt of the HSPS obtained in step 4) was added, and the mixture was stirred and dissolved for at least 48 h until uniformly dispersed. The electrolyte solution was ultrasonically degassed for 6 min, allowed to stand for 20 min, and then uniformly cast onto a Teflon template. After drying at room temperature for 6 h, it was vacuum dried at 60 °C for 24 h to obtain the electrolyte CPE.

[0121] Table 1. Results of ionic conductivity tests of solid polymer electrolytes at different temperatures.

[0122]

[0123] Table 1 shows that the blended organic-inorganic composite nanomaterials HSMS and HSPS significantly improved the ionic conductivity of the solid polymer electrolyte. The ionic conductivity of the modified solid polymer electrolyte was not less than 1×10⁻⁶ at 30℃. -4 S / cm. Furthermore, compared to the uncrosslinked SMS-3 particles, the solid polymer electrolyte with added hypercrosslinked HSMS-3 particles exhibits a significantly improved ionic conductivity.

[0124] In addition, TEM characterization was performed on groups 1-3 respectively to observe the morphological characteristics of the core-shell structured nanoparticles. The results are as follows: Figure 1 As shown. (a) to (f) are SEM images of SMS-1, SMS-2, SMS-3, HSMS-1, HSMS-2, and HSMS-3, respectively. From Figure 1As can be seen, the nanoparticles are all regularly shaped spheres, and the spherical morphology was not changed after the Friedel-Crafts alkylation hypercrosslinking reaction. TEM images show obvious core-shell structures, with the average particle size of mSiO2 being approximately 120 nm, and the shell thickness of SMS and HSMS being approximately 10-20 nm.

[0125] Example 2 was characterized by BET analysis to test the specific surface area of ​​the core-shell structured nanoparticles. The results are as follows: Figure 2 As shown. (a) to (b) are the nitrogen adsorption-desorption isotherms and pore size distribution diagrams for SMS-2 and HSMS-2, respectively. Figure 2 It can be seen that the specific surface area of ​​the nanoparticles before and after hypercrosslinking is 34 m². 2 g -1 and 58m 2 g -1 The specific surface area increases significantly after hypercrosslinking, and the pore size distribution is concentrated in the 1-2 nm range. The presence of the hypercrosslinked structure is beneficial to enhancing the specific surface area of ​​the interaction between PEO segments and lithium salt.

[0126] The modified solid polymer electrolyte membranes in Examples 1-3 and Example 7 were characterized by SEM and EDS distribution of Si, respectively. The results are as follows: Figure 3 As shown in the figure, (a) to (d) are SEM images of CSPE-mSiO2, CSPE-1, CSPE-2, and CSPE-3, respectively; (e) to (h) are EDS distribution diagrams of Si element in CSPE-mSiO2, CSPE-1, CSPE-2, and CSPE-3, respectively. It can be seen that the surface of CSPE-mSiO2 film is rough and uneven, and there is obvious particle aggregation of mSiO2. In contrast, the core-shell structured nanoparticles in CSPE-1, CSPE-2, and CSPE-3 are evenly distributed, and the film surface is relatively smooth, which is conducive to the formation of a good electrode / electrolyte contact interface.

[0127] The solid polymer electrolytes in Examples 1-6 and Example 8 were subjected to heat treatment at different temperatures and analyzed. The results are as follows: Figure 4 As shown. The reference polymer electrolyte SPE-PEO of Example 8 completely melted at 160°C. The solid polymer electrolyte membranes of Examples 4-6 were white films at room temperature and completely melted into yellow oily substances at 220°C. However, CSPE-1, CSPE-2, and CSPE-3, which contained cross-linked composite nanoparticles, did not melt at 260°C and maintained their intact morphology. This indicates that the presence of the cross-linked structure gives the solid polymer electrolyte membrane excellent thermal dimensional stability at high temperatures.

[0128] The linear sweep voltammograms of the solid polymer electrolytes in Examples 1-3 and Example 7 were analyzed, and the results are as follows: Figure 5As shown. The solid polymer electrolytes prepared in Examples 1-3 of this invention have an electrochemical window greater than 5V, and have the potential to be used with cathode materials at higher voltages.

[0129] The solid polymer electrolytes used in Examples 2 and 9 were assembled into Li / / Li symmetric coin cells, and the lithium-ion transference number was analyzed at room temperature. The results are as follows: Figure 6 As shown in the figure, (a) and (b) are the room-temperature lithium-ion transference numbers of the solid polymer electrolytes in Example 9 and Example 2, respectively. The lithium-ion transference number of the solid polymer electrolyte SPE-2 modified with pure organic nanoparticles is 0.16, while that of the solid polymer electrolyte CSPE-2 modified with composite nanoparticles is 0.34. The lithium-ion transference number is significantly increased, indicating that the added mSiO2 improves the mobility of lithium cations and reduces the concentration polarization between the two electrodes.

[0130] The solid polymer electrolytes from Examples 2 and 9 were assembled into Li / / Li symmetric button cells, and the lithium stability performance test curves were performed at 50°C as shown in the figure. Figure 7 As shown. (a) and (b) are the lithium stability curves of the solid polymer electrolyte in Example 9 and Example 2, respectively. The symmetric cell at 0.01 mA / cm²... 2 0.02mA / cm 2 0.05mA / cm 2 and 0.1mA / cm 2 Continuous constant current charge-discharge was performed at the specified current density, with the first three current densities each lasting 20 hours, for a total test duration of 300 hours. Each lithium delithiation / intercalation cycle lasted 1 hour. It can be seen that the initial overpotential of the symmetric cell gradually increases with increasing current density. SPE-2 at 0.1 mA / cm²... 2 The initial overpotential at the current density was 0.78V, and it increased continuously with the increase of the test time, reaching 0.9V after 300 hours. In contrast, CSPE-2 showed an overpotential of 0.1mA / cm². 2 The initial overpotential at the current density was 0.2V. With the uniform deposition of lithium, the interface stability increased, and the overpotential dropped to 0.15V after 300 hours. Compared with SPE-2, it has a lower overpotential and better interface stability for the lithium electrode. The composite nanoparticles added to the surface effectively suppressed the growth of lithium dendrites, promoted uniform lithium deposition, and improved interface stability.

[0131] The solid polymer electrolytes from Examples 1-3 and 7 were assembled into Li / / LiFePO4 coin cells, and the rate performance test curves at 50°C are shown below. Figure 8As shown, the discharge specific capacity of the modified solid polymer electrolytes in Examples 1-3 at different rates is higher than that of CSPE-mSiO2 in Example 7, exhibiting good rate performance.

[0132] As can be seen from the above embodiments, the cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte of the present invention has high ionic conductivity and interfacial stability, and its conductivity at room temperature (30℃) is not less than 1×10⁻⁶. -4 With an S / cm ratio and an electrochemical window greater than 5V, this material has the potential to be used with cathode materials operating at higher voltages and can be used over a wide temperature range. The Friedel-Crafts alkylation hypercrosslinking reaction not only does not alter the spherical morphology but also enhances the specific surface area of ​​the interaction between PEO segments and lithium salts, improving the thermal dimensional stability of the solid polymer electrolyte. The modified solid polymer electrolyte maintains good dimensional stability even at 260℃.

Claims

1. A cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte, characterized in that... The components include: The invention comprises a polymer matrix, a lithium salt, and a hypercrosslinked organic-inorganic composite filler. The hypercrosslinked organic-inorganic composite filler is a core-shell structured hypercrosslinked nanoparticle obtained by Friedel-Crafts reaction using an organic-inorganic copolymer as the reactant monomer. The inorganic component of the organic-inorganic copolymer is an inorganic filler modified with a double-bonded silane coupling agent, and the organic component is a random copolymer containing a benzene ring. The raw materials for the hypercrosslinked organic-inorganic composite filler include: an organic-inorganic copolymer, a catalyst, and a first crosslinking agent. The hypercrosslinked organic-inorganic composite filler is prepared by the following method: under anhydrous and oxygen-free conditions, the organic-inorganic copolymer is added as the reactant monomer to a Friedel-Crafts reaction system containing a catalyst, a first crosslinking agent, and a second solvent, and the reaction is carried out at a temperature of 25–80°C to obtain hypercrosslinked organic-inorganic nanoparticles. The particles; the first crosslinking agent is selected from at least one of dimethoxymethane or ethylene glycol dimethyl ether; the organic-inorganic copolymer is prepared by the following method: the inorganic filler, the first reactive monomer and the second reactive monomer are subjected to pre-crosslinking and free radical emulsion polymerization under the action of the second crosslinking agent, the initiator and the emulsifier to obtain the organic-inorganic copolymer; wherein, the first reactive monomer is styrene or a styrene derivative without strong electron-withdrawing groups, the second reactive monomer is selected from at least one of methyl methacrylate, methyl acrylate, vinyl acetate, polyethylene glycol monomethyl ether methacrylate or acrylonitrile; the inorganic filler is at least one of silane coupling agent modified SiO2, TiO2 or ZnO2; the second crosslinking agent is o-divinylbenzene, m-divinylbenzene or p-divinylbenzene.

2. The cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 1, characterized in that: The inorganic filler is SiO2 modified with silane coupling agent KH-570.

3. The cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 1 or 2, characterized in that: The initiator is at least one of potassium persulfate, ammonium persulfate, or sodium persulfate; The emulsifier is at least one of sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate, or sodium octadecylbenzenesulfonate.

4. A cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 1 or 2, characterized in that: The catalyst is selected from at least one of FeCl3, AlCl3, ZnCl2 or SnCl4.

5. A cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 1 or 2, characterized in that: The second solvent is at least one of 1,2-dichloroethane or dichloromethane.

6. A cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 1 or 2, characterized in that: The mass ratio of the second solvent to the organic-inorganic copolymer is 20-25:1, and the mass ratio of the first crosslinking agent to the organic-inorganic copolymer is 0.4-1.3:

1.

7. A cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 1 or 2, characterized in that: The mass fraction of the hypercrosslinked organic-inorganic composite filler in the electrolyte is 5-20%, and the molar ratio of the polymer matrix to the lithium salt satisfies N:Li = 10-20:1, where N is the structural unit in the polymer matrix that interacts with the lithium salt.

8. A cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 1 or 2, characterized in that: The polymer matrix is ​​selected from at least one of polyethylene oxide, polymethyl methacrylate, polyacrylonitrile, polyvinylidene fluoride, or polyvinylidene fluoride-hexafluoropropylene copolymer; The lithium salt is selected from at least one of lithium perchlorate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, and lithium trifluoromethanesulfonate.

9. The cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 8, characterized in that: The polymer matrix is ​​selected from polyethylene oxide.

10. A method for preparing a cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to any one of claims 1-9, characterized in that: In an anhydrous and oxygen-free environment, the super-crosslinked organic-inorganic composite filler, polymer matrix, and lithium salt are uniformly stirred in the first solvent to obtain an electrolyte solution. The solution is then cast into a mold and dried to obtain a solid polymer electrolyte membrane.

11. The method for preparing a cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 10, characterized in that: The first solvent is selected from at least one of anhydrous acetonitrile, tetrahydrofuran, N,N-dimethylformamide, acetone, and dichloromethane.

12. The method for preparing a cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 10, characterized in that: The electrolyte solution, after being uniformly stirred, is ultrasonically dispersed for 3-5 minutes, allowed to stand for 20-30 minutes for degassing, and then cast.

13. The method for preparing a cross-linked organic-inorganic nanomaterial modified solid polymer electrolyte according to claim 10, characterized in that: The drying conditions are: drying at room temperature for 6–12 h followed by vacuum drying at 60 °C for 12–24 h.

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