Preparation and Application of a Polymer-Based Composite Solid-State Electrolyte with High Ionic Conductivity

Abstract

Preparation and application of a polymer-based composite solid electrolyte with high ionic conductivity, belonging to the technical field of lithium-ion battery electrolytes. In the present invention, an organic-inorganic composite solid electrolyte is prepared by compounding a carbonate-based polymer, a conductive lithium salt, a porous support material, a functionalized silane coupling agent, and an inorganic ion conductor material. The polycarbonate-based polymer electrolyte has high ionic conductivity, a wide electrochemical window, and a high ion transference number; the functionalized silane coupling agent can form chemical bonds and interactions between the polymer and the inorganic material, acting as a bridge between the polymer and the inorganic filler, thereby improving the ionic conductivity of the polymer electrolyte and broadening its electrochemical window, improving the interfacial contact between the solid electrolyte and the positive and negative electrodes, and thus improving the charge and discharge performance of the lithium-ion battery. It is applicable to lithium-ion solid-state batteries with high-voltage cathode materials.

Description

Technical Field

[0001] The present invention relates to a solid electrolyte for lithium-ion batteries, in particular to a preparation method and application of a composite solid electrolyte that builds a bridge between polymers and inorganic materials, belonging to the technical field of lithium-ion battery electrolytes. Background Art

[0002] Lithium-ion batteries have been widely used in the fields of 3C consumer electronics, electric vehicles, and energy storage due to their many advantages such as high energy density, long cycle life, and no memory effect. Currently, most commercial lithium-ion batteries use conventional organic liquid electrolytes, which have huge safety problems such as easy volatilization, flammability, and explosiveness, seriously hindering the wider application of lithium-ion batteries. Therefore, using solid electrolytes to replace traditional organic electrolytes is one of the effective ways to solve the above-mentioned safety problems of lithium-ion batteries. At the same time, solid electrolytes also have advantages such as high ionic conductivity, wide electrochemical window, wide operating temperature, and can be arbitrarily cut or changed.

[0003] Current solid electrolytes mainly include inorganic solid electrolytes, polymer solid electrolytes, and organic-inorganic composite electrolytes. Inorganic solid electrolytes have advantages such as high mechanical strength and high room-temperature ionic conductivity; however, they also face huge problems, such as high density of electrolyte materials, high material rigidity, poor interfacial compatibility, and large interfacial impedance with electrodes. Organic polymer electrolytes have advantages such as good compatibility with lithium metal, simple preparation process, good flexibility, and adjustable shape and size, but their ionic conductivity is relatively low. Therefore, it is difficult to meet the actual needs of current lithium batteries using a single inorganic solid electrolyte or polymer electrolyte.

[0004] Polymer-based organic-inorganic composite electrolytes combine the advantages of organic materials and inorganic materials, and have been greatly improved in terms of ionic conductivity, electrochemical window, mechanical strength, etc., solving problems that cannot be solved by single components. The patent CN111435757B discloses a composite polymer electrolyte, its preparation method and a lithium-ion battery. The mass distribution of the inorganic lithium-conducting material in the composite polymer electrolyte changes in a decreasing or increasing manner along the thickness direction, which can improve the lithium-ion concentration difference at each interface, thereby improving lithium-ion transport to a certain extent. However, its ionic conductivity and electrochemical window still cannot match high-voltage cathode materials. CN110380114B provides an organic-inorganic composite solid electrolyte, its preparation method and application. The method can improve the agglomeration problem of inorganic conductor materials, thereby increasing ionic conductivity and inhibiting lithium dendrites, etc. However, on the one hand, the ionic conductivity in this patent is not high enough, and on the other hand, the ether-based polymers used are difficult to match the use of high-voltage cathode materials.

[0005] Therefore, in view of the problems existing in the prior art, it is necessary to provide a new organic-inorganic composite solid electrolyte membrane with a simple preparation method and the ability to withstand high voltages while ensuring high ionic conductivity. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method of a polycarbonate-based organic-inorganic composite solid electrolyte and its application in the field of lithium-ion batteries. In the polymer-based composite solid electrolyte provided by the present invention, chemical bonds are formed between the functionalized coupling agent and inorganic and organic materials, so that the inorganic solid electrolyte and the polymer are connected by a coupling agent, improving its ionic conductivity and electrochemical window, and showing excellent cycle stability when matched with high-voltage cathode materials.

[0007] To achieve the object of this invention, the technical solution of the present invention is as follows:

[0008] The present invention provides a polymer-based composite solid electrolyte with high ionic conductivity, and the raw materials include the following components: carbonate-based polymer, inorganic ion conductor, initiator or catalyst, lithium salt, and silane coupling agent;

[0009] The mass fraction of the carbonate-based polymer in the mixture is 10-96%, the mass fraction of the functionalized silane coupling agent in the mixture is 1-50%, the mass fraction of the conductive lithium salt in the mixture is 1-50%, the mass fraction of the inorganic ion conductor in the mixture is 1-50%, and the mass fraction of the initiator or catalyst in the mixture is 1-10%.

[0010] The carbonate-based polymer is selected from one or several of polymers such as polycarbonate, poly(ethylene carbonate), poly(ethylene glycol carbonate), poly(allyl methyl carbonate), poly(vinylidene carbonate), poly(fluorinated ethylene carbonate), etc. The C=O double bond in the carbonate group can form a chemical interaction with the active H on the silane coupling agent.

[0011] The inorganic lithium ion conductor material is an inorganic solid lithium ion electrolyte, and this material contains one or at least two combinations of hydroxyl group, carboxyl group or sulfhydryl group.

[0012] The silane coupling agent has a structure shown in Formula I:

[0013]

[0014] Wherein R1 is selected from any one of methyl, ethyl, and propyl; R2 is selected from any one of aminopropyl, aminoethyl, mercapto, or ureido.

[0015] The selected conductive lithium salt is one or more of the following: lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(trifluoromethanesulfonyl)methyl [LiC(SO2CF3)3].

[0016] The initiator or catalyst is one of the following: azobisisobutyronitrile (AIBN), azobisisoheptonitrile (ABVN), dibutyltin bis(acetylacetonate), dibutyltin dilaurate, dimethyl azobisisobutyrate (AIBME), benzoyl peroxide (BPO), platinum solution (Pt).

[0017] The preparation method of the high ionic conductivity organic-inorganic composite solid electrolyte is characterized by comprising the following steps:

[0018] (1) Take the inorganic ion conductor material, functionalized silane coupling agent, and organic solvent raw materials, stir and mix them evenly, heat and hydrolyze (with trace water in the reagent and air) at 30 - 80 °C for 12 - 24 hours, and then remove the solvent in a vacuum drying oven at 80 - 120 °C to prepare the silanized inorganic ion conductor material;

[0019] (2) Stir the silanized inorganic ion conductor material, carbonate-based polymer, conductive lithium salt, and organic solvent obtained in step (1) evenly; add the initiator or catalyst and stir evenly to form an electrolyte mixture; coat or immerse the above electrolyte mixture into a polytetrafluoroethylene mold containing a porous support material, and heat and cure at 60 - 120 °C for 4 - 12 hours to form a film;

[0020] The selected organic solvents in the above steps (1) and (2) are one or more of the following: N-methylpyrrolidone (NMP), ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylene glycol carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, acetonitrile, 1,2-dimethoxyethane, tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethyl sulfoxide.

[0021] The porous support material is one or more of cellulose non-woven fabric, polyethylene non-woven fabric, polypropylene non-woven fabric, glass fiber non-woven fabric, and polytetrafluoroethylene non-woven fabric. The preferred support material can improve the mechanical properties of the polymer-based composite electrolyte.

[0022] Taking the inorganic ion conductor with a hydroxyl group (X-OH) as an example, R2 is selected from any one of aminopropyl, aminoethyl, mercapto, or ureido, and the formation process of the above chemical bond is as follows:

[0023]

[0024] Coupling agents are used as a bridge between inorganic and organic substances to provide additional ion transport channels and reduce the interfacial resistance between organic and inorganic materials. The electrochemical stability of polymer-based composite electrolytes is enhanced by intermolecular interactions and stable chemical bonds. Intermolecular interactions include positive vacancy interactions, dipole-dipole interactions, and hydrogen bond interactions, etc.

[0025] Taking the carbonate-based polymer (Y-C(=O)-O-) and the R2 group as aminopropyl as an example, the formation process of the above-mentioned intermolecular chemical interactions is as follows:

[0026]

[0027] The present invention provides the application of the high ion conductivity polymer-based composite solid electrolyte in a lithium-ion battery.

[0028] A solid-state lithium-ion battery comprising the above-mentioned high ion conductivity polymer-based composite solid electrolyte, characterized in that it includes a positive electrode, a negative electrode, and the above-mentioned composite solid electrolyte disposed between the positive electrode and the negative electrode and having both the functions of a separator and an electrolyte.

[0029] The positive electrode active material of the lithium-ion battery is one or more of lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium lithium fluorophosphate, lithium manganese oxide, lithium manganate, lithium nickel manganate, lithium-rich materials (LLOs), lithium iron manganese phosphate, lithium nickel cobalt aluminate (NCA), lithium nickel cobalt manganate, lithium iron phosphate (LiFeO4), lithium vanadium phosphate (Li3V2(PO4)3); the negative electrode active material is one or more of metallic lithium, metallic lithium alloy, graphite, hard carbon, lithium metal nitride, antimony oxide, carbon-germanium composite material, carbon-silicon composite material, lithium titanate, lithium titanium oxide.

[0030] The preparation of the positive electrode of the lithium-ion battery includes the following steps: grinding and mixing 50-90% by mass of the positive electrode active material and 5-30% by mass of the conductive agent acetylene black; adding 1-15% by mass of polyvinylidene fluoride (PVDF), 1-15% by mass of the electrolyte mixture and 1-methyl-2-pyrrolidone (NMP) and grinding and mixing, and 1-methyl-2-pyrrolidone (NMP) is used to adjust the viscosity; coating on the surface of the aluminum foil and drying; metallic lithium and metallic lithium alloy can be directly used as the corresponding negative electrode, and the preparation of other negative electrodes includes the following steps: grinding and mixing 45-80% by mass of the negative electrode active material and 5-30% by mass of the conductive agent acetylene black; adding 5-25% by mass of polyvinylidene fluoride (PVDF) and 1-methyl-2-pyrrolidone (NMP) and grinding and mixing, and 1-methyl-2-pyrrolidone (NMP) is used to adjust the viscosity; coating on the surface of the copper foil and drying.

[0031] The above electrolyte mixture is preferably the electrolyte mixture formed during the preparation of the above high ionic conductivity organic-inorganic composite solid electrolyte.

[0032] The assembly of the lithium-ion battery includes coin cells and soft-pack batteries.

[0033] A chemical bond is formed between the coupling agent and the inorganic ion conductor material, and an intermolecular interaction is formed between the coupling agent and the carbonate-based polymer, reducing the interfacial resistance between the organic and inorganic components. The coupling agent serves as a bridge between the inorganic and organic substances to provide additional ion transport channels; the intermolecular interactions include one or more of chemical bond formation, hydrogen bond interaction, dipole-dipole interaction, and positive vacancy interaction. A stable chemical bond is formed between the inorganic material and the coupling agent, improving the problem of large interfacial impedance between the polymer and the inorganic conductor material, providing additional ion channels, and greatly increasing the ionic conductivity (room temperature ionic conductivity is 3.1×10 -3 S cm -1 ), and having a wider electrochemical stability window (5.3V / vs.Li + / Li).

[0034] The innovation and practicality of the present invention lie in:

[0035] 1. Using a carbonate-based polymer, which has a high ionic conductivity, and the composite solid electrolyte has excellent ion transport ability and thermal stability.

[0036] 2. The two-step method adopted in the present invention can effectively realize the construction of a bridge between the polymer chain and the inorganic material, reduce the interfacial resistance between the polymer phase and the inorganic phase, improve the interfacial compatibility, and increase the overall ionic conductivity; in addition, a stable chemical bond is formed between the coupling agent and the inorganic ion conductor, and an intermolecular interaction is formed with the C=O of the polymer chain, which can increase the ion transference number and the electrochemical window, significantly improve the compatibility between the electrolyte and the electrode interface, and thus improve the charge and discharge performance.

[0037] 3. The polymer-based organic-inorganic composite solid electrolyte provided by the present invention has an ionic conductivity as high as 3.1×10 -3 S cm -1 , the lithium ion transference number is above 0.64, and the electrochemical window is as high as 5.3V or more. The assembled solid-state lithium battery exhibits a Coulomb efficiency as high as 98% and excellent cycle stability at high voltages. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 LSV diagrams in Preparation Examples 1 and 5 of the high ionic conductivity polymer-based composite solid electrolyte.

[0039] Figure 2CV curve of the lithium-ion battery in Preparation Example 5 of the polymer-based composite solid-state lithium-ion battery with high ionic conductivity.

[0040] Figure 3 Charge-discharge curve of the solid-state lithium-ion battery assembled with the electrolyte in Example 5 and the lithium-rich cathode material. Detailed implementation mode

[0041] The present invention will be described below through specific examples. The examples are provided to better understand the present invention and in no way limit the scope of the present invention.

[0042] Preparation of electrolyte:

[0043] Example 1

[0044] 50 mg of lithium lanthanum zirconium tantalum oxide inorganic ion conductor (LLZTO) with a hydroxyl group on the surface and 150 mg of 3-aminopropyltriethoxysilane (APTES) were added to 2 mL of acetonitrile and stirred to obtain a mixed solution A1. After ultrasonic treatment for 30 min, it was stirred at 60 °C for 24 h; then it was transferred to a vacuum drying oven at 80 °C to remove the solvent, and white powder 1 of APTES@LLZTO was obtained; then 1 g of ethylene carbonate and 0.3 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed and stirred to obtain solution A2. The above APTES@LLZTO powder 1 (2 wt%) was mixed with solution A2 and 1% by mass of azobisisobutyronitrile (AIBN) of solution A2, and after ultrasonic treatment at room temperature for 30 min, it was stirred for 4 h to obtain an electrolyte mixture. On a polytetrafluoroethylene mold, with Whatman glass fiber membrane as the porous support framework, the uniformly stirred electrolyte mixture was scrape-coated on both sides of the Whatman membrane; it was heated in a vacuum drying oven at 80 °C for 10 hours to cure into an organic-inorganic composite electrolyte membrane with an average thickness of ~140 μm.

[0045] Example 2

[0046] 200 mg of lithium lanthanum zirconium tantalum oxide inorganic ion conductor (LLZTO) with hydroxyl groups on the surface and 200 mg of 3-aminopropyltriethoxysilane (APTES) were added to 4 mL of acetonitrile and stirred to obtain a mixed solution B1. After ultrasonic treatment for 30 min, it was stirred at 60 °C for 24 h; then it was transferred to a vacuum drying oven at 80 °C to remove the solvent, and white powder 2 of APTES@LLZTO was obtained; then 1 g of ethylene carbonate and 0.3 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed and stirred to obtain a solution B2. The above-mentioned APTES@LLZTO powder 2 (4 wt%) was mixed with the B2 solution and 1% by mass of azobisisobutyronitrile (AIBN) of the B2 solution, and after ultrasonic treatment at room temperature for 30 min, it was stirred for 4 h to obtain an electrolyte mixture. On a polytetrafluoroethylene mold, with Whatman glass fiber membrane as the porous support framework, the uniformly stirred electrolyte mixture was scrape-coated on both sides of the Whatman membrane; it was cured into an organic-inorganic composite electrolyte membrane by heating in a vacuum drying oven at 80 °C for 10 h, and the average thickness was ~143 μm.

[0047] Example 3

[0048] 100 mg of lithium lanthanum tantalum oxide inorganic ion conductor (LLTO) with hydroxyl groups on the surface and 100 mg of 3-aminopropyltriethoxysilane (APTES) were added to 2 mL of acetonitrile and stirred to obtain a mixed solution C1. After ultrasonic treatment for 30 min, it was stirred at 60 °C for 24 h; then it was transferred to a vacuum drying oven at 80 °C to remove the solvent, and white powder 3 of APTES@LLTO was obtained; then 1 g of ethylene carbonate and 0.3 g of lithium perchlorate (LiClO4) were mixed and stirred to obtain a solution C2. The above-mentioned APTES@LLTO powder 3 (2 wt%) was mixed with the C2 solution and 1% by mass of azobisisobutyronitrile (AIBN) of the C2 solution, and after ultrasonic treatment at room temperature for 30 min, it was stirred for 4 h to obtain an electrolyte mixture. On a polytetrafluoroethylene mold, with Whatman glass fiber membrane as the porous support framework, the uniformly stirred electrolyte mixture was scrape-coated on both sides of the Whatman membrane; it was cured into an organic-inorganic composite electrolyte membrane by heating in a vacuum drying oven at 80 °C for 10 h, and the average thickness was ~142 μm.

[0049] Example 4

[0050] 100 mg of lithium lanthanum zirconium tantalum oxide inorganic ion conductor (LLZTO) with hydroxyl groups on the surface and 200 mg of 3-aminopropyltriethoxysilane (APTES) were added to 2 mL of acetonitrile and stirred to obtain a mixed solution D1. After ultrasonic treatment for 30 min, it was stirred at 60 °C for 24 h; then it was transferred to a vacuum drying oven at 80 °C to remove the solvent, and white powder 4 of APTES@LLZTO was obtained; then 1 g of ethylene carbonate and 0.3 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed and stirred to obtain a solution D2. The above APTES@LLZTO powder (2 wt%) was mixed with the D2 solution and 1% by mass of azobisisobutyronitrile (AIBN) of the D2 solution, and after ultrasonic treatment at room temperature for 30 min, it was stirred for 4 h to obtain an electrolyte mixture. On a polytetrafluoroethylene mold, with Whatman glass fiber membrane as the porous support framework, the well-stirred electrolyte mixture was scrape-coated on both sides of the Whatman membrane; it was heated in a vacuum drying oven at 80 °C for 10 h to cure into an organic-inorganic composite electrolyte membrane with an average thickness of ~141 μm.

[0051] Example 5

[0052] 100 mg of lithium lanthanum zirconium tantalum oxide inorganic ion conductor (LLZTO) with hydroxyl groups on the surface and 100 mg of 3-aminopropyltriethoxysilane (APTES) were added to 2 mL of acetonitrile and stirred to obtain a mixed solution E1. After ultrasonic treatment for 30 min, it was stirred at 60 °C for 24 h; then it was transferred to a vacuum drying oven at 80 °C to remove the solvent, and white powder 5 of APTES@LLZTO was obtained; then 1 g of ethylene carbonate and 0.3 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed and stirred to obtain a solution E2. The above APTES@LLZTO powder 5 (8 wt%) was mixed with the E2 solution and 1% by mass of azobisisobutyronitrile (AIBN) of the E2 solution, and after ultrasonic treatment at room temperature for 30 min, it was stirred for 4 h to obtain an electrolyte mixture. On a polytetrafluoroethylene mold, with Whatman glass fiber membrane as the porous support framework, the well-stirred electrolyte mixture was scrape-coated on both sides of the Whatman membrane; it was heated in a vacuum drying oven at 80 °C for 10 h to cure into an organic-inorganic composite electrolyte membrane with an average thickness of ~146 μm.

[0053] Example 6

[0054] 100 mg of lithium lanthanum zirconium tantalum oxide inorganic ion conductor (LLZTO) with hydroxyl groups on the surface and 50 mg of 3-aminopropyltriethoxysilane (APTES) were added to 2 mL of acetonitrile and stirred to obtain a mixed solution F1. After ultrasonic treatment for 30 min, it was stirred at 60 °C for 24 h; then it was transferred to a vacuum drying oven at 80 °C to remove the solvent, and white powder 6 of APTES@LLZTO was obtained; then 1 g of ethylene carbonate and 0.3 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed and stirred to obtain solution F2. The above-mentioned APTES@LLZTO powder 6 (4 wt%) was mixed with F2 solution and 1% by mass of azobisisobutyronitrile (AIBN) of F2 solution, and after ultrasonic treatment at room temperature for 30 min, it was stirred for 4 h to obtain an electrolyte mixture. On a polytetrafluoroethylene mold, with Whatman glass fiber membrane as the porous support framework, the evenly stirred electrolyte mixture was scraped onto both sides of the Whatman membrane; it was cured into an organic-inorganic composite electrolyte membrane by heating in a vacuum drying oven at 80 °C for 10 h, and the average thickness was ~143 μm.

[0055] Electrolyte thickness: The thickness of the block copolymer electrolyte was measured using a micrometer (accuracy 0.01 mm), and 3 points on the membrane were randomly selected for measurement, and the average value was calculated.

[0056] Ionic conductivity: Two stainless steel gaskets were used to clamp the polymer electrolyte, and a button cell of R2032 was assembled to measure the impedance. According to the formula where L is the thickness of the polymer electrolyte, S is the area of the stainless steel gasket, and R is the measured impedance value.

[0057] Electrochemical window: A button cell of 2032 was assembled by clamping the polymer electrolyte with stainless steel and lithium metal, and linear voltammetry scanning (LSV) was performed for measurement. The starting voltage was 2.8 V, the highest potential was 5.5 V, and the scanning speed was 1 mV / S.

[0058] Example 7

[0059] 240 mg of lithium-rich manganese-based layered oxide cathode and 45 mg of conductive agent acetylene black were evenly ground for 40 min; 15 mg of binder polyvinylidene fluoride, 15 mg of electrolyte mixture (Example 5), and 150 μL of 1-methyl-2-pyrrolidone were added and evenly ground for 40 min; it was coated on the surface of aluminum foil and dried in vacuum at 80 °C for 8 h; the electrode sheet was cut into a disc with R = 12 mm, and the above-mentioned organic-inorganic composite electrolyte of Example 5 was used as the electrolyte, and metallic lithium was used as the anode to assemble a solid-state lithium-ion battery.

[0060] Example 8

[0061] 240 mg of lithium cobalt oxide cathode and 45 mg of conductive agent acetylene black were ground evenly for 40 min; 15 mg of binder polyvinylidene fluoride, 15 mg of electrolyte mixture (Example 5), and 150 μL of 1-methyl-2-pyrrolidone were added and ground evenly for 40 min; it was coated on the surface of aluminum foil and dried at 80 °C for 8 h under vacuum conditions; the electrode sheet was cut into a circular piece with R = 12 mm, and the organic-inorganic composite electrolyte of Example 5 above was used as the electrolyte, and metallic lithium was used as the anode to assemble a solid-state lithium-ion battery.

[0062] Table 1

[0063]

[0064]

Claims

1. A polymer-based composite solid electrolyte with high ionic conductivity, characterized in that, The raw materials include the following components: a carbonate-based polymer, an inorganic ion conductor, an initiator or catalyst, a conductive lithium salt, and a silane coupling agent; The mass fraction of the carbonate-based polymer in the mixture is 10-96%, the mass fraction of the silane coupling agent in the mixture is 1-50%, the mass fraction of the conductive lithium salt in the mixture is 1-50%, the mass fraction of the inorganic ion conductor in the mixture is 1-50%, and the mass fraction of the initiator or catalyst in the mixture is 1-10%; The carbonate-based polymer is selected from one or more of polycarbonate, poly(ethylene carbonate), poly(ethylene ethylene carbonate), poly(allyl methyl carbonate), poly(vinylidene carbonate), and poly(fluoroethylene carbonate); the C=O double bond in the carbonate group can form a chemical interaction with the active H on the silane coupling agent; The inorganic ion conductor is an inorganic solid lithium ion electrolyte, and the inorganic solid lithium ion electrolyte contains one or at least two combinations of hydroxyl, carboxyl, or sulfhydryl groups; The silane coupling agent has a structure shown in Formula I: , formula I wherein R1 is selected from any one of methyl, ethyl, and propyl; R2 is selected from any one of aminopropyl, aminoethyl, mercapto, or ureido.

2. A high ionic conductivity polymer-based composite solid electrolyte according to claim 1, characterized in that, The selected conductive lithium salt is one or more of the following: lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(trifluoromethanesulfonyl)methyl [LiC(SO2CF3)3]; The initiator or catalyst is one of the following: azobisisobutyronitrile (AIBN), azobisisoheptonitrile (ABVN), dibutyltin bis(acetylacetonate), dibutyltin dilaurate, dimethyl azobisisobutyrate (AIBME), benzoyl peroxide (BPO), and platinum (Pt).

3. A method for preparing a high ionic conductivity polymer-based composite solid electrolyte according to claim 1 or 2, characterized in that, It includes the following steps: (1) Take the inorganic ion conductor, silane coupling agent, and organic solvent, stir and mix them evenly, heat and hydrolyze at 30-80 °C for 12-24 hours, and then remove the solvent in a vacuum drying oven at 80-120 °C to prepare a silanized inorganic ion conductor; (2) Stir the silanized inorganic ion conductor, carbonate-based polymer, conductive lithium salt, and organic solvent obtained in step (1) evenly; add the initiator or catalyst and stir evenly to form an electrolyte mixture; coat or immerse the above electrolyte mixture into a polytetrafluoroethylene mold containing a porous support material, and heat and cure at 60-120 °C for 4-12 hours to form a film.

4. The method according to claim 3, characterized in that, The organic solvents selected in the above steps (1) and (2) are one or more of the following: N-methylpyrrolidone (NMP), ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylene glycol carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, acetonitrile, 1,2-dimethoxyethane, tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and dimethyl sulfoxide.

5. The method according to claim 3, characterized in that, The porous support material is one or more of cellulose non-woven fabric, polyethylene non-woven fabric, polypropylene non-woven fabric, glass fiber non-woven fabric, and polytetrafluoroethylene non-woven fabric.

6. The method according to claim 3, wherein Silane coupling agents are used as a bridge between inorganic and organic substances to provide additional ion transport channels and reduce the interfacial resistance between organic and inorganic materials. The electrochemical stability of polymer-based composite electrolytes is enhanced by intermolecular interactions and stable chemical bonds. Intermolecular interactions include positive vacancy interactions, dipole-dipole interactions, and hydrogen bond interactions.

7. Application of the polymer-based composite solid electrolyte with high ionic conductivity according to claim 1 or 2 in a lithium-ion battery.

8. A solid-state lithium-ion battery, characterized in that: It includes a positive electrode, a negative electrode, and a composite solid electrolyte with both separator and electrolyte functions placed between the positive electrode and the negative electrode. The composite solid electrolyte is the polymer-based composite solid electrolyte with high ionic conductivity according to claim 1 or 2.

9. The solid-state lithium-ion battery according to claim 8, characterized in that: The positive electrode active material of the lithium-ion battery is one or more of lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium fluorophosphate, lithium manganese oxide, lithium manganate, lithium nickel manganate, lithium-rich materials (LLOs), lithium iron manganese phosphate, lithium nickel cobalt aluminate (NCA), lithium nickel cobalt manganate, lithium iron phosphate (LiFeO4), lithium vanadium phosphate (Li3V2(PO4)3); the negative electrode active material is one or more of metallic lithium, lithium metal alloy, graphite, hard carbon, lithium metal nitride, antimony oxide, carbon-germanium composite material, carbon-silicon composite material, lithium titanate, lithium titanium oxide. The preparation of the positive electrode of the lithium-ion battery includes the following steps: grinding and mixing 50-90% by mass of the positive electrode active material and 5-30% by mass of the conductive agent acetylene black; adding 1-15% by mass of polyvinylidene fluoride (PVDF), 1-15% by mass of the electrolyte mixture, and 1-methyl-2-pyrrolidone (NMP) for grinding and mixing, and 1-methyl-2-pyrrolidone (NMP) is used to adjust the viscosity; coating on the surface of the aluminum foil and drying; metallic lithium and lithium metal alloy are directly used as the corresponding negative electrodes. The preparation of other negative electrodes includes the following steps: grinding and mixing 45-80% by mass of the negative electrode active material and 5-30% by mass of the conductive agent acetylene black; adding 5-25% by mass of polyvinylidene fluoride (PVDF) and 1-methyl-2-pyrrolidone (NMP) for grinding and mixing, and 1-methyl-2-pyrrolidone (NMP) is used to adjust the viscosity; coating on the surface of the copper foil and drying. The electrolyte mixture is the electrolyte mixture formed in step (2) of claim 3.

10. The solid-state lithium-ion battery according to claim 8, characterized in that: The assembly of the lithium-ion battery includes coin cells and soft-pack batteries.

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