Quasi-solid-state electrolyte, preparation method and application thereof, and button cell

Abstract

The application discloses a quasi-solid electrolyte, a preparation method and application thereof, and a button cell. The electrolyte contains a cyclodextrin crosslinked nitrile-containing polymer, an electrolyte, and an inorganic pore-forming agent. The quasi-solid electrolyte has a tensile strength of 2-3 MPa, a tensile rate of 30-80%, an ionic conductivity of 1-5 mS / cm, and is electrochemically stable in a voltage range of 1-4.6 V. The quasi-solid electrolyte is assembled into a quasi-solid lithium / sodium ion battery as a gel electrolyte, and has the advantages of high mechanical strength, good tensile property, high ionic conductivity, and a good electrochemical stability window.

Description

TECHNICAL FIELD

[0001] The present application relates to quasi-solid-state electrolyte and its preparation method and application and button cell. BACKGROUND

[0002] After conquering the portable electronic device market, lithium-ion batteries are now increasingly used in (hybrid) electric vehicles and stationary energy storage devices. For large-scale applications of lithium-ion batteries, a key issue is the safety problem. The existing alkali metal batteries usually use liquid electrolytes composed of thermally unstable salts (such as hexafluorophosphate) and highly flammable organic solvents (such as carbonates and ethers). The root cause of the battery safety problem is essentially due to a series of exothermic reactions, leading to uncontrollable thermal runaway of the battery system. The semi-solid-state electrolyte, also known as gel electrolyte, can solve the electrolyte leakage problem and enhance the safety guarantee. This semi-solid-state electrolyte not only maintains the excellent electrochemical performance (such as high ionic conductivity and excellent electrode | electrolyte interface compatibility) of liquid electrolyte, but also has good mechanical properties (strength, flexibility, etc.), which is beneficial to its application in the field of lithium-ion batteries.

[0003] The first gel electrolyte (based on poly(vinyl formal) / PVdF copolymer swelled with liquid organic carbonate) was reported by Feuillade and Perche in 1975, also known as quasi-solid-state electrolyte, semi-solid-state electrolyte or solid-liquid hybrid electrolyte. The basic idea is to develop a solid, mechanically stable, flexible and lightweight electrolyte, which fixes the liquid electrolyte in the polymer host matrix by forming a gel. The biggest advantage of semi-solid-state electrolyte is that it combines the beneficial properties of polymer matrix (i.e. mechanical stability, flexibility, reduced leakage) with the excellent ionic conductivity of liquid organic electrolyte by sharing the cohesive and diffusive properties of solids and liquids. In addition, the encapsulation of liquid electrolyte in the solid polymer host matrix leads to enhanced electrode / electrolyte contact and interface. SUMMARY

[0004] In view of the defects existing in the prior art, the purpose of the present application is to provide a quasi-solid-state electrolyte crosslinked with cyclodextrin and its preparation method and application. The quasi-solid-state electrolyte of the present application, as a gel electrolyte, is assembled into a quasi-solid-state lithium / sodium ion battery, which has the advantages of high mechanical strength, good tensile property, high ionic conductivity and good electrochemical stability window.

[0005] The application discloses a kind of quasi-solid electrolyte and preparation method thereof.The quasi-solid electrolyte comprises cyclodextrin crosslinked nitrile-containing polymer, electrolyte solvent and inorganic pore-forming agent.The quasi-solid electrolyte has high first charge-discharge capacity, good cycle stability and high coulombic efficiency.

[0006] According to a first aspect of the application, the application provides a quasi-solid electrolyte, which comprises cyclodextrin crosslinked nitrile-containing polymer, electrolyte solvent and inorganic pore-forming agent.

[0007] According to a second aspect of the application, the application provides a preparation method of the quasi-solid electrolyte, which comprises the following steps:

[0008] a) dissolving nitrile-containing polymer in an organic solvent, adding inorganic pore-forming agent to obtain a first solution;

[0009] b) mixing cyclodextrin with water to form a second solution;

[0010] c) coating the first solution on a mold;

[0011] d) placing the mold coated with the first solution into the second solution, and obtaining a porous composite after water removal;

[0012] e) immersing the porous composite into electrolyte to swell.

[0013] According to a third aspect of the application, the application provides application of the quasi-solid electrolyte or the quasi-solid electrolyte prepared by the method in a battery.

[0014] According to a fourth aspect of the application, the application provides a button cell, and the electrolyte of the button cell comprises the quasi-solid electrolyte or the quasi-solid electrolyte prepared by the method.

[0015] The quasi-solid electrolyte has a tensile strength of 2-3 MPa, a tensile rate of 30-80%, an ionic conductivity of 1-5 mS / cm, and is electrochemically stable in a voltage range of 1-4.6 V.

[0016] The quasi-solid electrolyte is assembled into a quasi-solid lithium / sodium ion battery as a gel electrolyte, and has the advantages of high mechanical strength, good tensile property, high ionic conductivity, and good electrochemical stability window. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 SEM image of the dynamic bond quasi-solid electrolyte of Example 1;

[0018] Figure 2 SEM image of the quasi-solid electrolyte without dynamic bond of Comparative Example 1;

[0019] Figure 3 Curve of the first charge-discharge of the dynamic bond quasi-solid electrolyte of Example 1;

[0020] Figure 4 Curve of the first charge-discharge of the quasi-solid electrolyte without dynamic bond of Comparative Example 1;

[0021] Figure 5 Discharge capacity of two samples of Example 1 and Comparative Example 1 after 0.1C activation, cycled at 0.5C for 100 cycles;

[0022] Figure 6 Cycle Coulombic efficiency comparison of two samples of Example 1 and Comparative Example 1, with a current density of 0.5C. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are provided as approximations. Any numerical value, however, can inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0024] All publications, patents, patent applications and other references mentioned in this specification are herein incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification are to be taken as commonly understood terms within the skill of the art. In case of conflict between the definitions of terms in this specification and those of a document incorporated herein by reference, the definitions provided in this specification control.

[0025] In the context of this specification, any two or more aspects of the application can be combined in any combination, the resulting technology falling within the scope of the original disclosure and the scope of the application.

[0026] Unless otherwise expressly stated, all percentages, parts, ratios, etc. in the present specification are by weight, unless the context otherwise requires.

[0027] In the present application, the quasi-solid electrolyte is also referred to as semi-solid electrolyte, gel electrolyte, or solid-liquid mixed electrolyte.

[0028] The present application provides a quasi-solid electrolyte, which comprises a cyclodextrin cross-linked nitrile-containing polymer, an electrolyte, and an inorganic pore-forming agent.

[0029] According to a preferred embodiment of the present application, the tensile strength of the quasi-solid electrolyte is 2-3 MPa.

[0030] According to a preferred embodiment of the present application, the tensile strength of the quasi-solid electrolyte is 2-3 MPa.

[0031] According to a preferred embodiment of the present application, the ionic conductivity of the quasi-solid electrolyte is 1-5 mS / cm; for example, 1.2 mS / cm, 1.4 mS / cm, 1.6 mS / cm, 1.8 mS / cm, 2 mS / cm, 2.2 mS / cm, 2.4 mS / cm, 2.6 mS / cm, 2.8 mS / cm, 3.0 mS / cm, 3.2 mS / cm, 3.4 mS / cm, 3.6 mS / cm, 3.8 mS / cm, 4.0 mS / cm, 4.2 mS / cm, 4.4 mS / cm, 4.6 mS / cm, 4.8 mS / cm; preferably 2-4.5 mS / cm.

[0032] According to a preferred embodiment of the present application, the mass ratio of the inorganic pore-forming agent to the nitrile-containing polymer is 0.5-5:1, preferably 1-1.5:1. By using the foregoing preferred embodiment, the film is not easily punctured, and has high mechanical strength.

[0033] According to a preferred embodiment of the present application, the mass ratio of the cyclodextrin to the nitrile-containing polymer is 0.1-1:1, preferably 0.3-0.6:1.

[0034] In the present application, the mass ratio of the electrolyte to the nitrile-containing polymer is 0.11-0.67:1, preferably 0.25-0.43:1, and in the examples, the amount of 0.3:1 is used as a demonstrative example, but the present application is not limited thereto.

[0035] In the present application, the optional range of the nitrile-containing polymer species is wide, and for the present application, according to a preferred embodiment of the present application, the nitrile-containing polymer includes but is not limited to one or more of polyacrylonitrile, polybutyrolactone, poly(acrylonitrile-co-styrene), poly(butyl acrylate-co-acrylonitrile), preferably polyacrylonitrile; preferably the nitrile-containing polymer is selected from one or more of molecular weights of 10W, 15W and 30W.

[0036] In the present application, the optional range of the cyclodextrin species is wide, and for the present application, preferably the cyclodextrin is selected from one or more of alpha-cyclodextrin, beta-cyclodextrin and gamma-cyclodextrin, preferably gamma-cyclodextrin. The foregoing preferred technical solution has the advantages of high tensile strength and large tensile rate when used for preparing a quasi-solid-state electrolyte.

[0037] In the present application, the optional range of the inorganic pore-forming agent species is wide, and for the present application, preferably the inorganic pore-forming agent includes but is not limited to one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-34 molecular sieve, aluminum oxide (Al2O3), silicon dioxide (SiO2) and titanium dioxide (TiO2), preferably selected from one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve and ZSM-34 molecular sieve; more preferably ZSM-5 molecular sieve.

[0038] According to a preferred embodiment of the present application, preferably the inorganic pore-forming agent is selected from ZSM-5 molecular sieve with a silica-alumina ratio of 30-80 and a specific surface area of 400-500 m 2 / g.

[0039] In the present application, the optional range of the electrolyte species is wide, and any commonly used electrolyte can be used in the present application, and for the present application, preferably in the electrolyte, the concentration of alkali metal salt is 0.5-1.2 mol / L.

[0040] In the present application, the optional range of the alkali metal salt species is wide, and for the present application, the alkali metal salt includes but is not limited to one or more of lithium salt, sodium salt and potassium salt; for the present application, preferably selected from lithium salt; more preferably the lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bisfluorosulfonimide (LiFSI), lithium bis-trifluoromethanesulfonimide (LiTFSI) and lithium perchlorate (LiClO4). The foregoing preferred technical solution has the advantages of high ionic conductivity and wide electrochemical stability window when used for preparing a semi-solid-state electrolyte.

[0041] In the present application, the electrolyte solvent is mainly used for swelling of the nitrile-containing polymer, and there is no special requirement for the type thereof. In the present application, the electrolyte solvent preferably includes, but is not limited to, one or more of dimethyl sulfoxide, N-methyl pyrrolidone, ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC) and ethylene glycol dimethyl ether (DME).

[0042] According to a preferred embodiment of the present application, the electrolyte solvent includes a first solvent and a second solvent, the first solvent is selected from one or more of dimethyl sulfoxide, N-methyl pyrrolidone, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate and ethylene glycol dimethyl ether; and the second solvent is selected from 4-trifluoromethyl ethylene carbonate.

[0043] According to a preferred embodiment of the present application, preferably, the first solvent is a mixture of ethylene carbonate and diethyl carbonate, and the mass ratio of the two is 0.1-10:1.

[0044] According to a preferred embodiment of the present application, preferably, the content of the first solvent is 80-95% by weight, and the content of the second solvent is 5-20% by weight, based on the total weight of the electrolyte solvent.

[0045] According to a preferred embodiment of the present application, the concentration of the alkali metal salt in the electrolyte is 0.5-1.2 mol / L.

[0046] According to a preferred embodiment of the present application, the present application provides a preparation method of the quasi-solid-state electrolyte, which includes:

[0047] a) dissolving the nitrile-containing polymer in an organic solvent, adding an inorganic pore-forming agent to obtain a first solution;

[0048] b) mixing the cyclodextrin with water to form a second solution;

[0049] c) coating the first solution on a mold;

[0050] d) placing the mold coated with the first solution into the second solution, and obtaining a porous composite after water removal;

[0051] e) swelling the porous composite in the electrolyte. The quasi-solid-state electrolyte prepared by using the foregoing preferred technical solutions has the advantages of high ionic conductivity and wide electrochemical stability window.

[0052] According to a preferred embodiment of the present application, preferably, the nitrile-containing polymer is dissolved in the organic solvent, and then stirred and mixed for 12-36 h.

[0053] According to the preferred embodiment of the present application, preferably, after the inorganic pore-forming agent is added, the mixture is stirred for 12-36 hours.

[0054] According to the preferred embodiment of the present application, preferably, the mold coated with the first solution is placed into the second solution, and then kept for 10-60 minutes.

[0055] According to the preferred embodiment of the present application, preferably, the preparation method comprises:

[0056] a) dissolving the nitrile-containing polymer in the organic solvent, stirring for 12-36 hours; adding the inorganic pore-forming agent, stirring for 12-36 hours, to obtain a first solution;

[0057] b) mixing the cyclodextrin with water to form a second solution;

[0058] c) coating the first solution on a mold;

[0059] d) placing the mold coated with the first solution into the second solution, keeping for 10-60 minutes, and forming a film after water removal;

[0060] e) immersing the porous composite into an electrolyte solution for swelling.

[0061] In the present application, the mold has no special requirements, and for the present application, the mold is preferably a commonly used mold such as glass.

[0062] According to the preferred embodiment of the present application, preferably, in the first solution, the concentration of the nitrile-containing polymer is 0.05-0.15 g / mL; and the concentration of the inorganic pore-forming agent is 0.075-0.225 g / mL.

[0063] According to the preferred embodiment of the present application, preferably, in the second solution, the concentration of the cyclodextrin is 0.01-0.016 g / mL.

[0064] According to the preferred embodiment of the present application, in the electrolyte solution, the concentration of the alkali metal salt is 0.5-1.2 mol / L.

[0065] In the present application, the water removal step and conditions have no special requirements, and a commonly used water removal method can be used. According to the preferred embodiment of the present application, the water removal step comprises: placing into a vacuum drying oven, vacuum heating and drying, the heating temperature is 80-120℃, the vacuum pressure is 2-3 MPa, and the heating time is 36-72 hours.

[0066] According to the preferred embodiment of the present application, the water removal step comprises: after being taken out, placing into a glove box with a water concentration lower than 0.01 ppm, and keeping for 7-14 days.

[0067] According to a preferred embodiment of the present application, the coating method has no special requirements, and any conventional coating method can be used in the present application. For the present application, uniform coating is preferred, and the method is blade coating with a blade thickness of 250-1000 μm.

[0068] According to a preferred embodiment of the present application, the swelling of the porous composite in the electrolyte is preferred, and the swelling time has no special requirements. For the present application, the preferred time is 5-90 min.

[0069] According to a preferred embodiment of the present application, the present application provides a method for preparing a cyclodextrin cross-linked quasi-solid-state electrolyte.

[0070] Preferably, the method comprises the following steps:

[0071] A) Dissolving polyacrylonitrile in an organic solvent and stirring at room temperature until complete dissolution;

[0072] Preferably, the polyacrylonitrile is a mixture of one or more of 10W, 15W and 30W molecular weight;

[0073] Preferably, the organic solvent is dimethyl sulfoxide;

[0074] B) After the dissolution of polyacrylonitrile, an inorganic pore-forming agent is added and stirred at room temperature;

[0075] Preferably, the inorganic pore-forming agent is selected from ZSM-5 molecular sieves with a silica-alumina ratio of 30-80, a two-channel intersection of 0.9 nm and a specific surface area of 400-500 m 2 / g;

[0076] Preferably, the stirring time is 12-24 h;

[0077] C) Dissolving cyclodextrin in deionized water and stirring until complete dissolution to obtain a cyclodextrin solution:

[0078] Preferably, the type of cyclodextrin is one or more of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin;

[0079] D) Uniformly coating the solution in A) on a flat glass plate, then placing the flat glass plate in the cyclodextrin solution in C), allowing the solution to exchange for a period of time, then drying the film in a vacuum drying oven, and swelling in an electrolyte;

[0080] According to a preferred embodiment of the present application, the uniform coating is preferably performed by blade coating with a blade thickness of 250-1000 μm.

[0081] According to a preferred embodiment of the present application, the exchange time in the solution is preferably 30-90 min.

[0082] According to the preferred embodiment of the present application, preferably, the drying temperature of the vacuum drying is 80-120℃, and the heating time is 36-60h.

[0083] E) Assembling the three-layer porous solid-state electrolyte film described in D) with lithium / sodium sheet, lithium / sodium ion positive electrode sheet, gasket and spring sheet into a button cell.

[0084] The present application provides the application of the quasi-solid-state electrolyte prepared by the method described in the present application in a battery. The quasi-solid-state electrolyte of the present application has the advantages of good contact with the electrode and high ionic conductivity when applied in a battery.

[0085] The present application provides a button cell, the electrolyte of which contains the quasi-solid-state electrolyte described in the present application. The button cell obtained by using the electrolyte of the present application has the advantages of high first discharge capacity and high coulombic efficiency.

[0086] In order to facilitate the understanding of the present application, the present application lists the following embodiments. However, those skilled in the art should understand that the embodiments are only to help understand the present application, and should not be regarded as specific limitations on the present application. The endpoints and any values disclosed herein are not limited to the precise range or value, and should be understood to include values close to these ranges or values.

[0087] Example 1

[0088] 1. Preparation method of quasi-solid-state electrolyte containing dynamic cross-linking bond

[0089] 2g of polyacrylonitrile with a molecular weight of 15W was dissolved in 18mL of dimethyl sulfoxide, and stirred magnetically at room temperature for 12h to obtain a polyacrylonitrile solution. 3g of ZSM-5 with a silicon aluminum ratio of 45 and a specific surface area of 450m 2 / g was added and stirred for 24h.

[0090] 1g of γ-cyclodextrin was added to 99ml of deionized water and stirred until completely dissolved, and then poured into a clean flat tray.

[0091] The above solution was uniformly coated on a flat glass plate with a 1000 μm doctor blade, slowly placed into the tray containing the cyclodextrin solution, and allowed to replace the solvent for 45 min. After the film was formed, it was placed in a vacuum oven and heated at 100°C for 48 h to obtain a dry porous film. The porous film was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to determine its crystalline properties and microstructure. The strength and elongation at break were tested using a tensile tester at a tensile speed of 100 mm / min. The porous film was swelled in a lithium ion electrolyte for 5 min, and then punched to the desired size to obtain a quasi-solid-state electrolyte. The lithium ion electrolyte was composed of 1 mol / L LiPF6 dissolved in ethylene carbonate EC / diethyl carbonate DEC / 4-trifluoromethyl ethylene carbonate (EC / DEC / 4-trifluoromethyl ethylene carbonate mass ratio: 4.5:4.5:1), and the mass ratio of the electrolyte to the nitrile-containing polymer was 0.3:1.

[0092] 2. Assembly and testing of quasi-solid-state lithium ion batteries

[0093] The above-synthesized porous semi-solid-state electrolyte was used as an electrolyte to assemble a 2035 button cell with a lithium sheet, a lithium iron phosphate anode sheet (lithium iron phosphate: polyvinylidene fluoride: acetylene black = 8:1:1), a gasket, and a spring. The obtained battery was tested for capacity (charge and discharge current was 0.1C) and cycle stability (charge and discharge current was 0.5C) using constant current charge and discharge. The semi-solid-state electrolyte was assembled into a 2035 button cell with a lithium sheet, a stainless steel sheet, and a spring, and its electrochemical stability window was tested using linear sweep voltammetry at a scan rate of 1 mV s -1 5 Hz.

[0094] Figure 1 The SEM image of the quasi-solid-state electrolyte of Example 1 with dynamic bonding is shown in the figure, which shows that the material has a uniform distribution of voids, a dense microstructure, and uniform distribution of inorganic particles, which is beneficial to prevent dendrite penetration;

[0095] Figure 2 The SEM image of the quasi-solid-state electrolyte of Comparative Example 1 without dynamic bonding is shown in the figure, which shows that the material has a relatively loose morphology and many pore structures, which is not conducive to preventing dendrite penetration;

[0096] Figure 3 The first charge and discharge curve of the quasi-solid-state electrolyte of Example 1 with dynamic bonding is shown in the figure, and the current density was 0.1C. The first discharge capacity was as high as 174 mAh / g -1 , which was greatly improved compared to the comparative sample;

[0097] Figure 4 The first charge and discharge curve of the quasi-solid-state electrolyte of Comparative Example 1 without dynamic bonding is shown in the figure, and the first discharge capacity was 165 mAh / g.​-1 ;

[0098] Figure 5 The discharge capacity of the two samples of Example 1 and Comparative Example 1 after 0.1C activation at 0.5C for 100 cycles shows that the cyclodextrin cross-linked polynitrile greatly improves the electrochemical stability window of the uncross-linked gel polymer;

[0099] Figure 6 The comparison of the cycle coulombic efficiency of the two samples of Example 1 and Comparative Example 1 at a current density of 0.5C shows that the coulombic efficiency of Example 1 is significantly improved, indicating that the battery of Example 1 has better reversibility and less electrolyte decomposition.

[0100] Example 2

[0101] 1. Preparation method of quasi-solid-state electrolyte containing dynamic cross-linking bonds

[0102] Dissolve 2g of polyacrylonitrile with a molecular weight of 15W in 18mL of dimethyl sulfoxide, magnetically stir at room temperature for 12h to obtain a polyacrylonitrile solution. Add 3g of ZSM-5 with a silicon-aluminum ratio of 45 and a specific surface area of 450m 2 / g, stir for 24h.

[0103] Take 1g of α-cyclodextrin and add it to 99ml of deionized water, stir until completely dissolved, then pour into a clean flat tray.

[0104] Take the above solution and evenly coat it on a flat glass plate with a 1000μm spatula, slowly put it into the tray containing the cyclodextrin solution, allow the solvent to displace, and keep it for 45min. After the film is formed, put it into a vacuum oven and heat it at 100℃ for 48h to obtain a dry porous film. Test its strength and elongation at break with a tensile testing machine at a tensile speed of 100mm / min. Swell the porous film in lithium ion electrolyte for 5min, then punch it to the desired size to obtain the quasi-solid-state electrolyte. The composition of the lithium ion electrolyte is 1mol / L LiPF6 dissolved in EC / DEC / 4-trifluoromethyl ethylene carbonate (4.5:4.5:1), and the mass ratio of electrolyte to nitrile-containing polymer is 0.3:1.

[0105] 2. Assembly and testing of quasi-solid-state lithium ion battery

[0106] The above-synthesized porous semi-solid electrolyte was used as electrolyte to assemble 2035 button cell with lithium sheet, lithium iron phosphate anode sheet (lithium iron phosphate: polyvinylidene fluoride: acetylene black = 8: 1: 1), gasket and spring. The obtained battery was tested for capacity by constant current charge and discharge (charge and discharge current was 0.1C). The semi-solid electrolyte was assembled into 2035 button cell with lithium sheet, stainless steel sheet and spring, and its electrochemical stability window was tested by linear sweep voltammetry (scan rate was 1 mV s -1 The conductivity of the semi-solid electrolyte was tested by electrochemical impedance spectroscopy (test frequency was 0.01-10 5 Hz.

[0107] Example 3

[0108] 1. Preparation method of quasi-solid electrolyte containing dynamic cross-linking bond

[0109] 2.0 g of polybutenenitrile with a molecular weight of 15 W was dissolved in 18 mL of dimethyl sulfoxide, and stirred magnetically at room temperature for 12 h to obtain a polybutenenitrile solution. 3 g of ZSM-5 with a silicon-aluminum ratio of 45 and a specific surface area of 450 m 2 / g was added and stirred for 24 h.

[0110] 1 g of γ-cyclodextrin was added to 99 ml of deionized water and stirred until completely dissolved, and then poured into a clean flat tray.

[0111] The above solution was uniformly coated on a flat glass plate with a 1000 μm doctor blade, slowly placed into the tray containing the cyclodextrin solution, and the solvent was replaced for 45 min. After the film was formed, it was placed in a vacuum oven and heated at 100°C for 48 h to obtain a dry porous film. The strength and elongation at break of the film were tested by a tensile tester at a tensile speed of 100 mm / min. The porous film was swelled in lithium ion electrolyte for 5 min, and then punched to the required size to obtain a quasi-solid electrolyte. The composition of the lithium ion electrolyte was 1 mol / L LiPF6 dissolved in EC / DMC / 4-trifluoromethyl carbonic acid vinyl ester (4.5:4.5:1), and the mass ratio of electrolyte to nitrile-containing polymer was 0.3:1.

[0112] 2. Assembly and testing of quasi-solid lithium ion battery

[0113] The above-synthesized porous semi-solid electrolyte was used as electrolyte to assemble 2035 button cell with lithium sheet, lithium iron phosphate anode sheet (lithium iron phosphate: polyvinylidene fluoride: acetylene black = 8: 1: 1), gasket and spring. The obtained battery was tested for capacity by constant current charge and discharge (charge and discharge current was 0.1C). The semi-solid electrolyte was assembled into 2035 button cell with lithium sheet, stainless steel sheet and spring, and its electrochemical stability window was tested by linear sweep voltammetry (scan rate was 1 mV s -1Its conductivity was measured using electrochemical impedance spectroscopy at a frequency of 0.01–10⁻⁶. 5 Hz.

[0114] Example 4

[0115] 1. Preparation method of quasi-solid electrolyte containing dynamic cross-linking bonds

[0116] 2 g of polyacrylonitrile with a molecular weight of 15W was dissolved in 18 mL of dimethyl sulfoxide and magnetically stirred at room temperature for 12 h to obtain a polyacrylonitrile solution. 3 g of silica was then added and the mixture was stirred for 24 h.

[0117] Add 1g of γ-cyclodextrin to 99ml of deionized water, stir until completely dissolved, and then pour into a clean flat-bottomed tray.

[0118] The above solution was uniformly coated onto a flat glass plate using a 1000 μm doctor blade. The plate was then slowly placed into a tray containing the cyclodextrin solution to allow solvent displacement. This process was maintained for 45 minutes to allow the membrane to form. After this process, the membrane was placed in a vacuum oven and heated at 100°C for 48 hours to obtain a dry porous membrane. Its strength and elongation at break were tested using a tensile testing machine at a stretching speed of 100 mm / min. The porous membrane was then immersed in a lithium-ion electrolyte for 5 minutes to swell, and then kneaded to the desired size to obtain a quasi-solid electrolyte. The lithium-ion electrolyte consisted of 1 mol / L NaPF6 dissolved in EC / DMC / 4-trifluoromethyl ethylene carbonate (4.5:4.5:1), with a mass ratio of electrolyte to nitrile-containing polymer of 0.3:1.

[0119] 2. Assembly and testing of quasi-solid-state lithium-ion batteries

[0120] The synthesized porous semi-solid electrolyte was used as the electrolyte and assembled with lithium foil, lithium iron phosphate cathode (lithium iron phosphate: polyvinylidene fluoride: acetylene black = 8:1:1), gasket, and spring to form a 2035 coin cell. The capacity of the resulting battery was tested using a constant current charge-discharge method (charge-discharge current of 0.1C). The electrochemical stability window of the 2035 coin cell assembled with the semi-solid electrolyte, lithium foil, stainless steel sheet, and spring was tested using a linear sweep voltammetry method at a scan rate of 1 mV / s. -1 Its conductivity was measured using electrochemical impedance spectroscopy at a frequency of 0.01–10⁻⁶. 5 Hz.

[0121] Example 5

[0122] 1. Preparation method of quasi-solid electrolyte containing dynamic cross-linking bonds

[0123] 2 g of polyacrylonitrile (molecular weight 15W) was dissolved in 18 mL of dimethyl sulfoxide and magnetically stirred at room temperature for 12 h to obtain a polyacrylonitrile solution. 3 g of a silicon-to-aluminum ratio of 45:1 was added, resulting in a specific surface area of ​​450 m². 2 Add 1g of ZSM-5 and stir for 24 hours. Add 1g of γ-cyclodextrin to 99ml of deionized water and stir until completely dissolved. Then pour into a clean flat-bottomed tray.

[0124] The above solution was uniformly coated onto a flat glass plate using a 1000 μm doctor blade. The plate was then slowly placed into a tray containing the cyclodextrin solution to allow solvent displacement. This process was maintained for 45 minutes to allow the membrane to form. After this process, the membrane was placed in a vacuum oven and heated at 100°C for 48 hours to obtain a dry porous membrane. Its strength and elongation at break were tested using a tensile testing machine at a stretching speed of 100 mm / min. The porous membrane was then immersed in a lithium-ion electrolyte to swell for 5 minutes, and then kneaded to the desired size to obtain the quasi-solid electrolyte. The lithium-ion electrolyte composition was 1 mol / L. -1 The LiPF6 was dissolved in EC / DEC (1:1), and the mass ratio of the electrolyte to the nitrile-containing polymer was 0.3:1.

[0125] 2. Assembly and testing of quasi-solid-state lithium-ion batteries

[0126] The synthesized porous semi-solid electrolyte was used as the electrolyte and assembled with lithium foil, lithium iron phosphate cathode (lithium iron phosphate: polyvinylidene fluoride: acetylene black = 8:1:1), gasket, and spring to form a 2035 coin cell. The capacity of the resulting battery was tested using a constant current charge-discharge method (charge-discharge current of 0.1C). The electrochemical stability window of the 2035 coin cell assembled with the semi-solid electrolyte, lithium foil, stainless steel sheet, and spring was tested using a linear sweep voltammetry method at a scan rate of 1 mV / s. -1 Its conductivity was measured using electrochemical impedance spectroscopy at a frequency of 0.01–10⁻⁶. 5 Hz.

[0127] Example 6

[0128] 1. Preparation method of quasi-solid electrolyte containing dynamic cross-linking bonds

[0129] 2 g of polyacrylonitrile (molecular weight 15W) was dissolved in 18 mL of dimethyl sulfoxide and magnetically stirred at room temperature for 12 h to obtain a polyacrylonitrile solution. 3 g of a solution with a silica-to-alumina ratio of 45:5 and a specific surface area of ​​450 m² was then added. 2 / g of ZSM-5, stirred for 24h.

[0130] Add 1g of γ-cyclodextrin to 99ml of deionized water, stir until completely dissolved, and then pour into a clean flat-bottomed tray.

[0131] The above solution was uniformly coated onto a flat glass plate using a 1000 μm doctor blade. The plate was then slowly placed into a tray containing the cyclodextrin solution to allow solvent displacement. This process was maintained for 45 minutes to allow the membrane to form. After this process, the membrane was placed in a vacuum oven and heated at 60°C for 48 hours to obtain a dry porous membrane. Its strength and elongation at break were tested using a tensile testing machine at a stretching speed of 100 mm / min. The porous membrane was then immersed in a lithium-ion electrolyte for 5 minutes to swell, and then kneaded to the desired size to obtain the quasi-solid electrolyte. The lithium-ion electrolyte composition was 0.8 mol / L. -1 LiPF6 was dissolved in EC / DEC / 4-trifluoromethyl ethylene carbonate (4.5:4.5:1), with the mass ratio of electrolyte to nitrile-containing polymer being 0.3:1.

[0132] 2. Assembly and testing of quasi-solid-state lithium-ion batteries

[0133] The synthesized porous semi-solid electrolyte was used as the electrolyte and assembled with lithium foil, lithium iron phosphate cathode (lithium iron phosphate: polyvinylidene fluoride: acetylene black = 8:1:1), gasket, and spring to form a 2035 coin cell. The capacity of the resulting battery was tested using a constant current charge-discharge method (charge-discharge current of 0.1C). The electrochemical stability window of the 2035 coin cell assembled with the semi-solid electrolyte, lithium foil, stainless steel sheet, and spring was tested using a linear sweep voltammetry method at a scan rate of 1 mV / s. -1 Its conductivity was measured using electrochemical impedance spectroscopy at a frequency of 0.01–10⁻⁶. 5 Hz.

[0134] Comparative Example 1

[0135] 1. Synthesis of quasi-solid-state electrolytes without dynamic cross-linking bonds

[0136] 2 g of polyacrylonitrile (PAI) with a molecular weight of 15W was dissolved in 20 mL of dimethyl sulfoxide (DMSO) and the solution was magnetically stirred at room temperature for 12 h to obtain a PAI solution. 3 g of ZSM-5m³, with a silicon-to-aluminum ratio of 450 and a specific surface area of ​​450, was then added. 2 / g, stir for 24 hours.

[0137] The above solution was uniformly coated onto a flat glass plate using a 1000 μm doctor blade. It was then slowly placed into a tray containing deionized water to allow solvent displacement. This process was maintained for 45 minutes, after which the membrane was formed. The membrane was then placed in a vacuum oven and heated at 100 °C for 48 hours to obtain a dry porous membrane. The porous membrane's crystallinity and microstructure were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Its strength and elongation at break were tested using a tensile testing machine at a stretching speed of 100 mm / min. After swelling in a lithium-ion electrolyte for 5 minutes, the membrane was then rolled to the desired size to obtain a quasi-solid electrolyte. The lithium-ion electrolyte consisted of 1 mol / L LiPF6 dissolved in EC / DEC / 4-trifluoromethyl ethylene carbonate (4.5:4.5:1), with a mass ratio of electrolyte to nitrile-containing polymer of 0.3:1.

[0138] 2. Assembly and testing of all-solid-state lithium-ion batteries

[0139] The synthesized porous electrolyte membrane was used as the electrolyte and assembled with lithium foil, lithium iron phosphate cathode (lithium iron phosphate: polyvinylidene fluoride: acetylene black = 8:1:1), gasket, and spring sheet to form a 2035 coin cell. The resulting battery was tested for capacity (charge / discharge current of 0.1C) and cycle stability (charge / discharge current of 0.5C) using a constant current charge / discharge method. The semi-solid electrolyte, assembled with lithium foil, stainless steel sheet, and spring sheet to form a 2035 coin cell, had its electrochemical stability window tested using a linear sweep voltammetry method at a scan rate of 1 mV / s. -1 Its conductivity was measured using electrochemical impedance spectroscopy at a frequency of 0.01–10⁻⁶. 5 Hz.

[0140] Table 1

[0141]

[0142] The embodiments described above are merely illustrative of the detailed process of the present invention, but the present invention is not limited to the above detailed process; that is, the present invention does not depend on the steps described in the above embodiments for implementation. In summary, any improvements made to the present invention by those skilled in the art, including substitutions for the raw materials and additives described in the present invention, and selections of specific implementation methods, are all within the scope of protection and disclosure of the present invention.

[0143] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A quasi-solid-state electrolyte, characterized in that, The electrolyte contains a nitrogen-containing polymer crosslinked with cyclodextrin, an electrolyte solution, and an inorganic pore-forming agent; the cyclodextrin is γ-cyclodextrin, and the inorganic pore-forming agent is selected from one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve, and ZSM-34 molecular sieve.

2. The quasi-solid electrolyte according to claim 1, wherein, The tensile strength of the quasi-solid electrolyte is 2-3 MPa; and / or The elongation of the quasi-solid electrolyte is 30-80%; and / or The ionic conductivity of the quasi-solid electrolyte is 1-5 mS / cm; and / or The mass ratio of cyclodextrin to the anitrile-containing polymer is 0.1-1:1; and / or The mass ratio of the inorganic pore-forming agent to the acrylonitrile-containing polymer is 0.5-5:1; and / or The mass ratio of electrolyte to nitrile-containing polymer is 0.11-0.67:

1.

3. The quasi-solid-state electrolyte according to claim 2, wherein, The elongation of the quasi-solid electrolyte is 60-75%; and / or The quasi-solid electrolyte has an ionic conductivity of 2-4.5 mS / cm; and / or The mass ratio of cyclodextrin to the nitrile-containing polymer is 0.3-0.6:1; and / or The mass ratio of the inorganic pore-forming agent to the acrylonitrile-containing polymer is 1-1.5:1; and / or The mass ratio of electrolyte to a nitrile-containing polymer is 0.25-0.43:

1.

4. The quasi-solid electrolyte according to claim 1, wherein, The nitrile-containing polymer is selected from one or more of polyacrylonitrile, polybutadiene nitrile, poly(acrylonitrile-co-styrene), poly(butyl acrylate-co-acrylonitrile), and poly(ethylene oxide-co-acrylonitrile); and / or The inorganic pore-forming agent is ZSM-5 molecular sieve; and / or The concentration of alkali metal salt in the electrolyte is 0.5-1.2 mol / L; and / or The electrolyte solvent is selected from one or more of dimethyl sulfoxide, N-methylpyrrolidone, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, and ethylene glycol dimethyl ether.

5. The quasi-solid-state electrolyte according to claim 4, wherein, The nitrile-containing polymer is polyacrylonitrile; and / or The inorganic pore-forming agent is selected from those with a silicon-to-aluminum ratio between 30 and 80 and a specific surface area of ​​400-500 m². 2 / g of ZSM-5 molecular sieve; and / or The alkali metal salt is selected from one or more of lithium, sodium, and potassium salts; and / or The electrolyte solvent includes a first solvent and a second solvent. The first solvent is selected from one or more of dimethyl sulfoxide, N-methylpyrrolidone, ethylene carbonate, diethyl carbonate, dimethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, and ethylene glycol dimethyl ether. The second solvent is selected from 4-trifluoromethyl ethylene carbonate. The first solvent is a mixture of ethylene carbonate and diethyl carbonate, with a mass ratio of 0.1-10:

1. Based on the total weight of the electrolyte solvent, the content of the first solvent is 80-95% by weight, and the content of the second solvent is 5-20% by weight.

6. The quasi-solid-state electrolyte according to claim 4, wherein, The nitrile-containing polymer is selected from one or more of the molecular weights of 10 W, 15 W, and 30 W; and / or The alkali metal salt is selected from lithium salts.

7. The quasi-solid-state electrolyte according to claim 6, wherein, The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoroformyl)imide, and lithium perchlorate.

8. A method for preparing a quasi-solid-state electrolyte, characterized in that, The preparation method includes: a) The nitrile-containing polymer is dissolved in an organic solvent, and an inorganic pore-forming agent is added to obtain the first solution; b) Mix cyclodextrin with water to form a second solution; c) The first solution is applied to the mold; d) The mold coated with the first solution is placed in the second solution, and after water removal, a porous composite is obtained; e) Immerse the porous composite in an electrolyte to swell; The cyclodextrin is γ-cyclodextrin; The inorganic pore-forming agent is selected from one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve, and ZSM-34 molecular sieve.

9. The preparation method according to claim 8, wherein, The preparation method includes: a) The nitrile-containing polymer is dissolved in an organic solvent and stirred for 12-36 h; an inorganic pore-forming agent is added and stirred for 12-36 h to obtain the first solution; b) Mix cyclodextrin with water to form a second solution; c) The first solution is applied to the mold; d) Place the mold coated with the first solution into the second solution and keep it for 10-60 minutes to remove water and form a film; e) Immerse the porous composite in an electrolyte to swell.

10. The preparation method according to claim 8 or 9, wherein, The nitrile-containing polymer is selected from one or more of polyacrylonitrile, polybutadiene nitrile, poly(acrylonitrile-co-styrene), poly(butyl acrylate-co-acrylonitrile), and poly(ethylene oxide-co-acrylonitrile); and / or The inorganic pore-forming agent is selected from those with a silicon-to-aluminum ratio between 30 and 80 and a specific surface area of ​​400-500 m². 2 / g of ZSM-5 molecular sieve; and / or The organic solvent is selected from dimethyl sulfoxide and / or N-methylpyrrolidone; and / or The concentration of alkali metal salt in the electrolyte is 0.5-1.2 mol / L; and / or The electrolyte solvent is selected from one or more of dimethyl sulfoxide, N-methylpyrrolidone, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, and ethylene glycol dimethyl ether.

11. The preparation method according to claim 10, wherein, The nitrile-containing polymer is selected from one or more polyacrylonitrile polymers with a molecular weight of 10 W, 15 W and 30 W; and / or The alkali metal salt is selected from one or more of lithium, sodium, and potassium salts; and / or The electrolyte solvent includes a first solvent and a second solvent. The first solvent is selected from one or more of dimethyl sulfoxide, N-methylpyrrolidone, ethylene carbonate, diethyl carbonate, dimethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, and ethylene glycol dimethyl ether. The second solvent is selected from 4-trifluoromethyl ethylene carbonate. The first solvent is a mixture of ethylene carbonate and diethyl carbonate, with a mass ratio of 0.1-10:

1. Based on the total weight of the electrolyte solvent, the content of the first solvent is 80-95% by weight, and the content of the second solvent is 5-20% by weight.

12. The preparation method according to claim 11, wherein, The alkali metal salt is selected from lithium salts.

13. The preparation method according to claim 12, wherein, The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoroformyl)imide, and lithium perchlorate.

14. The preparation method according to claim 8 or 9, wherein, In the first solution, the concentration of the nitrile-containing polymer is 0.05-0.15 g / mL; the concentration of the inorganic pore-forming agent is: 0.075 -0.225 g / mL; and / or In the second solution, the concentration of cyclodextrin is 0.01-0.016 g / ml.

15. The preparation method according to claim 8 or 9, wherein, The dehydration step includes: placing the product in a vacuum drying oven and drying it under vacuum heating at a temperature of 80-120 ℃ for 36-72 h.

16. The application of the quasi-solid-state electrolyte according to any one of claims 1-7 or the quasi-solid-state electrolyte prepared by the method according to any one of claims 8-15 in a battery.

17. A button cell battery, characterized in that, The electrolyte of the coin cell contains the quasi-solid-state electrolyte as described in any one of claims 1-7 or the quasi-solid-state electrolyte prepared by the method described in any one of claims 8-15.

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