Solid electrolyte membrane, preparation method thereof and secondary battery

Abstract

The invention provides a solid electrolyte membrane, a preparation method thereof and a secondary battery. The solid electrolyte membrane comprises an organic-inorganic composite membrane and an inorganic salt electrolyte, the organic-inorganic composite membrane comprises an organic phase and an inorganic phase, and the inorganic salt electrolyte is located at an interface gap of the organic phase and the inorganic phase. The solid electrolyte membrane provided by the invention not only has good conductivity, but also has excellent toughness and deformation resistance.

Description

Technical Field

[0001] This invention belongs to the field of new energy battery technology, specifically relating to a solid electrolyte membrane and its preparation method, and a secondary battery. Background Technology

[0002] With the widespread application of lithium-ion batteries in new energy vehicles, portable electronic devices, and energy storage systems, the requirements for their safety and energy density continue to increase. Traditional organic liquid electrolytes, due to their flammability, leakage, and poor stability, and their susceptibility to decomposition, gas generation, and thermal runaway under high temperature and high voltage environments, pose serious safety hazards and cannot meet the dual requirements of high safety and high reliability for next-generation high-performance energy storage devices. Therefore, solid-state electrolytes, as a core alternative material for achieving high safety and high energy density in next-generation lithium-ion batteries, are receiving widespread attention and in-depth research.

[0003] Currently, solid-state electrolytes under research are mainly classified into polymer-type, inorganic ceramic-type, and organic-inorganic composite-type. Among them, polymer-type electrolytes have significant advantages due to their good flexibility, such as multifunctionality in shape, flexibility, and lightweight, making it easier to form good electrode / electrolyte contacts. However, their inherent low room-temperature ionic conductivity severely hinders their practical application. Inorganic ceramic-type electrolytes, although possessing high ionic conductivity and thermal stability, generally suffer from high brittleness and poor flexibility, making it difficult to achieve good interfacial adhesion with electrodes and resulting in high interfacial resistance. Organic-inorganic composite solid-state electrolytes combine the advantages of the above two types of electrolytes, enabling large-scale manufacturing and reducing the manufacturing cost of solid-state batteries. However, they still have problems such as low conductivity, complex manufacturing processes, and poor consistency, which greatly limit their application in solid-state batteries.

[0004] In other words, existing solid electrolytes suffer from problems such as discontinuous interfacial conduction, lack of stable ion migration channels, low ion mobility, poor interfacial compatibility, and complex processes. Therefore, a new solid electrolyte is needed to meet application requirements. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a solid electrolyte membrane, its preparation method, and a secondary battery.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a solid electrolyte membrane, the solid electrolyte membrane comprising an organic-inorganic composite membrane and an inorganic salt electrolyte, wherein the organic-inorganic composite membrane comprises an organic phase and an inorganic phase, and the inorganic salt electrolyte is located at the interface gap between the organic phase and the inorganic phase.

[0008] Compared to the inorganic-organic composite solid electrolytes currently available, which mainly achieve ion conduction through two pathways: 1) polymers serve as lithium-ion migration channels, while inorganic materials assist in structural regulation; 2) inorganic materials construct ion migration channels, while polymers provide flexible support and bonding.

[0009] This invention utilizes the difference in thermal shrinkage rates between the inorganic and organic phases to actively induce the formation of a gap structure. An inorganic salt electrolyte is then placed within this gap structure, transforming it into a continuous ion migration channel to prepare a solid electrolyte membrane. This method offers the following advantages:

[0010] i. This invention utilizes the interfacial gap structure between the inorganic and organic phases as an ion migration channel. The ion migration channel is ordered and controllable, and the interface distribution has good continuity. That is, the solid electrolyte membrane provided by this invention realizes ion conduction at the interface between the organic and inorganic phases, which breaks through the problem of easy breakage of ion paths in traditional composite systems and solves the problem of performance degradation of existing composite solid electrolytes.

[0011] ii. The solid electrolyte membrane provided by the present invention can achieve excellent ion conduction performance at room temperature and has excellent interfacial stability, which avoids the problem of low ion conductivity of pure organic phase and the problem of severe performance degradation of inorganic solid electrolyte.

[0012] iii. The solid electrolyte membrane provided by the present invention has both conductivity and excellent mechanical strength.

[0013] Preferably, the mass ratio of the organic phase to the inorganic phase is 5:5 to 1:9. In this case, based on the total mass of the inorganic and organic phases as 100%, the content of the organic phase is 10-50%, such as 10%, 20%, 30%, 40%, 50%, etc., and the content of the inorganic phase is 90-50%, such as 90%, 80%, 70%, 60%, 50%, etc. In this case, the mass ratio of the two can be 1:9, 2:8, 3:7, 4:6 or 5:5, preferably 3:7.

[0014] When the mass ratio of the organic phase material to the inorganic phase material is within the range defined in this invention, a continuous ion migration channel can be formed in the obtained solid electrolyte membrane, and the mechanical properties of the solid electrolyte membrane are good. If there is too much organic phase material, it is difficult to form an effective continuous ion conduction network, which will lead to a decrease in ionic conductivity. If there is too little organic phase material, the electrolyte membrane is prone to increased brittleness and decreased flexibility, making it easy to break and difficult to process, thus reducing conductivity. When the organic phase material is severely insufficient, lithium salt dissolution and continuous ion migration channels will also be interrupted, which will lead to a severe decrease in ionic conductivity.

[0015] Preferably, the mass of the inorganic salt electrolyte is 0.1-5 wt% of the total mass of the solid electrolyte membrane, such as 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc., and preferably 2-3 wt% can achieve optimal performance, such as 2.4 wt%.

[0016] Preferably, the organic phase material includes any one or a combination of at least two of the following: polyethylene oxide, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate, polyimide, polystyrene, or chitosan.

[0017] Preferably, the inorganic phase material includes any one or a combination of at least two of zirconium oxide, tin oxide, aluminum oxide, yttrium oxide, bismuth oxide, zinc oxide, titanium oxide, silicon oxide, or boron nitride.

[0018] Preferably, the inorganic salt electrolyte includes any one or a combination of at least two of lithium salt, sodium salt, or potassium salt.

[0019] Preferably, the lithium salt comprises any one or a combination of at least two of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethyl flavonoid, lithium bis(trifluoromethyl sulfonyl)imide, lithium bis(perfluoroethyl sulfonyl)imide, lithium bisfluorosulfonylimide, or lithium bis(oxalatoborate).

[0020] Preferably, the sodium salt comprises any one or a combination of at least two of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, or sodium bis(trifluoromethylsulfonyl)imide.

[0021] Preferably, the potassium salt comprises potassium hexafluorophosphate and / or potassium difluorosulfonamide.

[0022] Preferably, the thickness of the solid electrolyte membrane is 10-50 μm, such as 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0023] Preferably, the diameter of the solid electrolyte membrane is 10-19 mm, such as 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, etc.

[0024] In a second aspect, the present invention provides a method for preparing a solid electrolyte membrane as described in the first aspect, the method comprising:

[0025] S1. Prepare an organic-inorganic composite membrane by mixing organic phase materials and inorganic phase materials;

[0026] S2. Inducing the organic-inorganic composite membrane to generate interphase gaps;

[0027] S3. Inorganic salt electrolyte enters the interphase gap to obtain the solid electrolyte membrane.

[0028] like Figures 1-3 As shown, the present invention utilizes the difference in thermal shrinkage rates between the inorganic and organic phases to actively induce the formation of a gap structure, and then places the inorganic salt electrolyte in the gap structure, thereby transforming the gap structure into a continuous ion migration channel to prepare a solid electrolyte membrane.

[0029] The preparation method provided by this invention is simple and easy to implement, requiring no complex filler modification or high-temperature sintering steps, but only low-temperature induction of different shrinkage behaviors.

[0030] Preferably, the method for preparing the organic-inorganic composite membrane in step S1 includes:

[0031] S11. Mix the organic phase material and the inorganic phase material in a solvent to form a slurry;

[0032] S12. The slurry is coated and dried to obtain the organic-inorganic composite membrane.

[0033] Preferably, the solid content of the slurry is 15-25 wt%, such as 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, etc.

[0034] Preferably, the solvent comprises any one or a combination of at least two of the following: N-methylpyrrolidone, N,N-dimethylformamide, acetonitrile, tetrahydrofuran, ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, γ-valerolactone, ethyl acetate, methyl formate, 2-methyltetrahydrofuran, dimethoxymethane, dimethoxypropane, 1,3-dioxolane, ethylene glycol dimethyl ether, dimethyl sulfoxide, xylene, or fluoroethers.

[0035] Preferably, step S2 specifically involves placing the organic-inorganic composite membrane in a low-temperature environment to create interphase gaps at the interface between the organic phase material and the inorganic phase material. The temperature of the low-temperature environment is ≤-10℃, such as -10℃, -11℃, -15℃, -18℃, -20℃, etc.

[0036] Preferably, the method of placing the organic-inorganic composite membrane in a low-temperature environment includes: firstly inducing the organic-inorganic composite membrane in liquid nitrogen, preferably for an induction time of 5-15s, such as 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, etc., and then storing it in an environment with a temperature ≤-10℃, preferably for 5-12h, such as 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, etc., so that interphase gaps are generated at the interface between the organic phase material and the inorganic phase material.

[0037] In this invention, since the thermal expansion coefficients of the organic and inorganic phases are significantly different, under low-temperature induction, the organic and inorganic phases will form interfacial gaps due to the difference in shrinkage. This invention obtains a solid electrolyte membrane by setting inorganic electrolyte salts in the interfacial gaps, thereby fixing the electrolyte in the interfacial region.

[0038] Preferably, step S3 specifically includes:

[0039] S31. Cool the inorganic salt electrolyte solution to ≤-10℃, such as -10℃, -11℃, -15℃, -18℃, -20℃, -30℃, -40℃, -50℃, etc.;

[0040] S32. In an environment of ≤-10℃, the organic-inorganic composite membrane with interphase gaps is immersed in the inorganic salt electrolyte solution;

[0041] S33. After immersion, remove the membrane, remove excess solution from the surface, and dry to obtain the solid electrolyte membrane.

[0042] Preferably, the concentration of the inorganic salt electrolyte solution is 0.5-1.5 mol / L, such as 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, etc.

[0043] Thirdly, the present invention provides a secondary battery comprising the solid electrolyte membrane described in the first aspect.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The solid electrolyte membrane provided by the present invention utilizes the difference in thermal shrinkage rates between the organic and inorganic phases to actively induce the formation of a gap structure and transform it into a continuous ion-conducting interface layer, so that ion migration no longer depends on the accidental contact between traditional random fillers.

[0046] (2) The solid electrolyte membrane provided by the present invention breaks through the bottleneck of organic phase chain segment movement and the problem of hard connection of inorganic channels, and lithium ion migration is mainly completed at the organic / inorganic interface;

[0047] (3) The solid electrolyte membrane provided by the present invention uses an organic phase as a flexible support framework and an inorganic phase to provide rigidity reinforcement. The two work together to have good toughness and resistance to deformation.

[0048] (4) The solid electrolyte membrane provided by the present invention has both good conductivity and excellent toughness and deformation resistance.

[0049] (5) The preparation method provided by the present invention abandons the traditional preparation methods that rely on complex surface modification or sintering processes, and induces the formation of functional structural gaps at low temperature conditions solely through the difference in intrinsic thermophysical properties of the material. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of the organic-inorganic composite membrane prepared in Example 1 of the present invention;

[0051] Figure 2 This is a schematic diagram of the structure of the organic-inorganic composite membrane obtained in Example 1 of the present invention after low-temperature treatment;

[0052] Figure 3 This is a schematic diagram of the structure of the solid electrolyte membrane obtained in Embodiment 1 of the present invention. Detailed Implementation

[0053] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0054] Unless otherwise specified, the raw materials involved in the following specific embodiments of the present invention are all conventional materials in the art, and can be purchased from commercially available products. Some raw material information is as follows:

[0055] PVDF: Polyvinylidene fluoride, with a coefficient of thermal expansion of approximately 127.8 × 10⁻⁶. -6 / ℃, Solvay Solef PVDF5130 (USA);

[0056] PEO: Polyethylene oxide, coefficient of thermal expansion 150×10⁻⁶ -6 / ℃, purchased from Aladdin;

[0057] ZrO2: Zirconia, coefficient of thermal expansion 10×10⁻⁶ -6 / ℃, purchased from Aladdin;

[0058] SiO2: Silicon oxide, coefficient of thermal expansion 0.55×10-6 / ℃, purchased from Aladdin;

[0059] Example 1

[0060] This embodiment provides a solid electrolyte membrane and its preparation method, as follows:

[0061] (1) PVDF and inorganic ZrO2 particles with a particle size of 100 nm are mixed with solvent NMP at a mass ratio of 3:7 to form a uniform slurry. The total mass fraction of solute in the slurry is 20 wt%.

[0062] (2) The slurry is coated on the substrate material, dried at 60℃ for 1 hour and then dried at 120℃ for 2 hours to obtain an organic-inorganic composite film with a thickness of 32μm.

[0063] (3) The organic-inorganic composite membrane was immersed in liquid nitrogen and left to stand for 10 seconds, and then left to stand at -20℃ for 6 hours so that the organic and inorganic phases would have gaps between them due to the difference in thermal expansion coefficients.

[0064] (4) Prepare a 1 mol / L LiTFSI / ethanol solution and store it at -20℃;

[0065] (5) Immerse the organic-inorganic composite membrane obtained in step (3) in LiTFSI / ethanol solution to allow the lithium salt solution to penetrate into the gaps at the organic / inorganic interface.

[0066] (6) Remove the membrane, restore it to room temperature, wipe off the excess solution on the surface, and dry it in a vacuum drying oven at 70°C for 8 hours to fix the lithium salt in the interface area, thus obtaining the solid electrolyte membrane with a thickness of 34 μm.

[0067] Example 2-3

[0068] This embodiment provides a solid electrolyte membrane and its preparation method.

[0069] The difference from Example 1 is that in this example, the mass ratio of PVDF to ZrO2 is 4:6 (Example 2) and 2:8 (Example 3).

[0070] Example 4

[0071] This embodiment provides a solid electrolyte membrane and its preparation method, as follows:

[0072] (1) PEO and inorganic SiO2 particles with a particle size of 200 nm are mixed with the solvent tetrahydrofuran at a mass ratio of 3:7 to form a uniform slurry. The total mass fraction of solute in the slurry is 25 wt%.

[0073] (2) The slurry is coated on the substrate material, dried at 60℃ for 1 hour and then dried at 120℃ for 2 hours to obtain an organic-inorganic composite film with a thickness of 31μm.

[0074] (3) The organic-inorganic composite membrane was immersed in liquid nitrogen and left to stand for 10 seconds, and then left to stand at -18℃ for 6 hours so that the organic and inorganic phases would have gaps between them due to the difference in thermal expansion coefficients.

[0075] (4) Prepare a 1.5 mol / L LiPF6 / ethanol solution and store it at -18℃;

[0076] (5) Immerse the organic-inorganic composite membrane obtained in step (3) in LiPF6 / ethanol solution to allow the lithium salt solution to penetrate into the gaps at the organic / inorganic interface.

[0077] (6) Remove the membrane, restore it to room temperature, wipe off the excess solution on the surface, and dry it in a vacuum drying oven at 70°C for 8 hours to fix the lithium salt in the interface area, thus obtaining the solid electrolyte membrane with a thickness of 32 μm.

[0078] Example 5

[0079] This embodiment provides a solid electrolyte membrane and its preparation method, as follows:

[0080] (1) PEO and inorganic ZrO2 particles with a particle size of 100 nm are mixed with tetrahydrofuran solvent at a mass ratio of 3:7 to form a uniform slurry. The total mass fraction of solute in the slurry is 15 wt%.

[0081] (2) The slurry is coated on the substrate material, dried at 60℃ for 1 hour and then dried at 120℃ for 2 hours to obtain an organic-inorganic composite film with a thickness of 31μm.

[0082] (3) The organic-inorganic composite membrane was immersed in liquid nitrogen and left to stand for 10 seconds, and then left to stand at -40℃ for 6 hours so that the organic and inorganic phases would have gaps between them due to the difference in thermal expansion coefficients.

[0083] (4) Prepare a 0.5 mol / L LiBF4 / ethanol solution and store it at -40℃;

[0084] (5) The organic-inorganic composite membrane obtained in step (3) is immersed in LiBF4 / ethanol solution to allow the lithium salt solution to penetrate into the gaps at the organic / inorganic interface.

[0085] (6) Remove the membrane, restore it to room temperature, wipe off the excess solution on the surface, and dry it in a vacuum drying oven at 70°C for 8 hours to fix the lithium salt in the interface area, thus obtaining the solid electrolyte membrane with a thickness of 32 μm.

[0086] Comparative Example 1

[0087] This comparative example provides a solid electrolyte membrane and its preparation method.

[0088] The difference from Example 1 is that in this comparative example, step (1) does not introduce zirconium oxide.

[0089] Comparative Examples 2-3

[0090] This comparative example provides a solid electrolyte membrane and its preparation method.

[0091] The difference from Example 1 is that, in this comparative example, the mass ratio of PVDF to ZrO2 is 6:4 (Comparative Example 2) and 0.8:9.2 (Comparative Example 3).

[0092] Performance testing:

[0093] (1) The composite solid electrolyte membranes prepared in the examples and comparative examples were cut. The composite solid electrolyte discs were assembled into a simulated experimental battery of “gold-plated copper sheet / electrolyte / gold-plated copper sheet”, and the battery was subjected to an external pressure of 10 MPa.

[0094] Open the electrochemical workstation and call the AC impedance method (EIS) program. Set the test frequency range to 1MHz to 100mHz and the perturbation voltage to 10mV, perform the test, and obtain the corresponding Nyquist spectrum.

[0095] The resistance R is obtained by circuit fitting of the Nyquist spectrum, and the ionic conductivity σ of the composite solid electrolyte is calculated according to the formula.

[0096] σ = L / (R·S);

[0097] S: Cross-sectional area of ​​a standard stainless steel gasket, in square centimeters (cm²). 2 );

[0098] L: Thickness of the solid electrolyte, in centimeters (cm);

[0099] R: The measured resistance of the solid electrolyte, measured in ohms (Ω).

[0100] The test results are shown in Table 1:

[0101] Table 1

[0102] sample Ionic conductivity (S / cm) Example 1 <![CDATA[1.35*10 -3 ]]> Example 2 <![CDATA[4.71*10 -4 ]]> Example 3 <![CDATA[2.54*10 -4 ]]> Example 4 <![CDATA[1.32*10 -4 ]]> Example 5 <![CDATA[7.86*10 -4 ]]> Comparative Example 1 <![CDATA[2.58*10 -6 ]]> Comparative Example 2 <![CDATA[6.29*10 -5 ]]> Comparative Example 3 <![CDATA[3.79*10 -7 ]]>

[0103] (2) Tensile strength can be tested according to the test standard of GB / T 1040.1-2018, 3.6.2;

[0104] (3) The compressive strength can be tested according to the test standard of ASTM E2546-15.

[0105] As can be seen from the examples and performance tests, the solid electrolyte membrane obtained by the preparation method provided by the present invention has excellent ionic conductivity and mechanical properties.

[0106] As can be seen from the comparison of Examples 1-3 and Comparative Examples 2-3, when the mass ratio of organic phase to inorganic phase in the present invention is in the range of 5:5 to 1:9, the obtained solid electrolyte membrane has both high conductivity and mechanical strength.

[0107] The applicant declares that the technical solution of this invention is illustrated through the above embodiments, but this invention is not limited to the above process steps, that is, it does not mean that this invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A solid electrolyte membrane, characterized in that, The solid electrolyte membrane comprises an organic-inorganic composite membrane and an inorganic salt electrolyte, wherein the organic-inorganic composite membrane comprises an organic phase and an inorganic phase, and the inorganic salt electrolyte is located at the interface gap between the organic phase and the inorganic phase.

2. The solid electrolyte membrane according to claim 1, characterized in that, The mass ratio of the organic phase to the inorganic phase is 5:5 to 1:9; Preferably, based on the total mass of the inorganic and organic phases as 100%, the content of the organic phase is 10-50%, and the content of the inorganic phase is 90-50%. Preferably, the mass of the inorganic salt electrolyte is 0.1-5 wt% of the total mass of the solid electrolyte membrane.

3. The solid electrolyte membrane according to claim 1 or 2, characterized in that, The organic phase material includes any one or a combination of at least two of the following: polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate, polyimide, polystyrene, or chitosan; Preferably, the inorganic phase material includes any one or a combination of at least two of zirconium oxide, tin oxide, aluminum oxide, yttrium oxide, bismuth oxide, zinc oxide, titanium oxide, silicon oxide, or boron nitride; Preferably, the inorganic salt electrolyte includes any one or a combination of at least two of lithium salt, sodium salt, or potassium salt; Preferably, the lithium salt comprises any one or a combination of at least two of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethyl xanthate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(perfluoroethylsulfonyl)imide, lithium bisfluorosulfonylimide, or lithium bis(oxalatoborate). Preferably, the sodium salt comprises any one or a combination of at least two of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, or sodium bis(trifluoromethylsulfonyl)imide. Preferably, the potassium salt comprises potassium hexafluorophosphate and / or potassium difluorosulfonamide.

4. The solid electrolyte membrane according to any one of claims 1-3, characterized in that, The thickness of the solid electrolyte membrane is 10-50 μm; Preferably, the diameter of the solid electrolyte membrane is 10-19 mm.

5. A method for preparing a solid electrolyte membrane as described in any one of claims 1-4, characterized in that, The preparation method includes: S1. Prepare an organic-inorganic composite membrane by mixing organic phase materials and inorganic phase materials; S2. Inducing the organic-inorganic composite membrane to generate interphase gaps; S3. Inorganic salt electrolyte enters the interphase gap to obtain the solid electrolyte membrane.

6. The preparation method according to claim 5, characterized in that, The method for preparing the organic-inorganic composite membrane in step S1 includes: S11. Mix the organic phase material and the inorganic phase material in a solvent to form a slurry; S12. The slurry is coated and dried to obtain the organic-inorganic composite membrane; Preferably, the solid content of the slurry is 15-25 wt%. Preferably, the solvent comprises any one or a combination of at least two of the following: N-methylpyrrolidone, N,N-dimethylformamide, acetonitrile, tetrahydrofuran, ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, γ-valerolactone, ethyl acetate, methyl formate, 2-methyltetrahydrofuran, dimethoxymethane, dimethoxypropane, 1,3-dioxolane, ethylene glycol dimethyl ether, dimethyl sulfoxide, xylene, or fluoroethers.

7. The preparation method according to claim 5 or 6, characterized in that, Step S2 specifically involves placing the organic-inorganic composite membrane in a low-temperature environment to create interphase gaps at the interface between the organic and inorganic phase materials, wherein the temperature of the low-temperature environment is ≤-10℃.

8. The preparation method according to any one of claims 5-7, characterized in that, Step S3 is as follows: S31. Cool the inorganic salt electrolyte solution to ≤-10℃; S32. In an environment of ≤-10℃, the organic-inorganic composite membrane with interphase gaps is immersed in the inorganic salt electrolyte solution; S33. After immersion, remove the membrane, remove excess solution from the surface, and dry to obtain the solid electrolyte membrane.

9. The preparation method according to claim 8, characterized in that, The concentration of the inorganic salt electrolyte solution is 0.5-1.5 mol / L.

10. A secondary battery, characterized in that, Includes the solid electrolyte membrane according to any one of claims 1-4.

Images