Preparation method and application of high-temperature-resistant and high-pressure-resistant solid electrolyte membrane with gradient structure

Abstract

The invention discloses a preparation method and application of a high-temperature-resistant and high-pressure-resistant solid-state electrolyte membrane with a gradient structure, and belongs to the technical field of solid-state batteries. The specific scheme is as follows: the method comprises the following steps: step 1, dropwise adding thermal response polymer precursor slurry on a porous polymer film substrate until the slurry is uniformly dispersed on the porous polymer film substrate to obtain a pre-polymerized film; and 2, uniformly coating the pre-polymerized film with the photoresponse polymer precursor slurry, and carrying out photo-initiation until the outer-layer photoresponse polymer precursor slurry is completely polymerized, so as to obtain the solid electrolyte film. According to the invention, passive protection is changed into active self-adaption, and the contradiction that high ionic conductivity and high safety as well as good interface contact and high mechanical strength are difficult to achieve at the same time is ingeniously solved through gradient design and an integrated preparation process; and a promising solution is provided for constructing a next-generation lithium / sodium battery with high safety and high energy density.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a method for preparing and applying a gradient-structured high-temperature and high-pressure resistant solid electrolyte membrane. Background Technology

[0002] Currently, liquid rechargeable batteries remain the most widely used batteries in the consumer electronics, electric vehicle, and energy storage battery fields. However, due to the inherent chemical properties of liquid organic solvents, liquid rechargeable batteries still face the following challenges: the flammable and volatile liquid electrolyte is highly susceptible to ignition and explosion during thermal runaway; the liquid electrolyte can undergo side reactions with the electrodes and produce lithium dendrites, leading to capacity decay and short-circuit risks, thus limiting battery life and reliability. All-solid-state batteries, with their advantages of high energy density, intrinsic non-flammability, high safety, and long cycle life, completely eliminate the risks of flammability and leakage associated with traditional liquid electrolytes, fundamentally avoiding thermal runaway accidents such as battery fires and explosions. However, the poor solid-solid interface contact in all-solid-state batteries results in extremely high interfacial impedance, and the ionic conductivity often fails to meet practical requirements, leading to poor rate capability and cycle performance, severely restricting the commercial application of all-solid-state batteries.

[0003] Gel polymer electrolytes combine the safety and high ionic conductivity of solid organic electrolytes. However, while traditional gel polymer electrolytes exhibit high ionic conductivity due to the presence of liquid plasticizers, they still have shortcomings when facing thermal runaway. When the temperature rises sharply, the melting of the polymer backbone and the decomposition of the liquid plasticizer cause the gel polymer electrolyte to lose its mechanical strength, failing to effectively prevent contact between the positive and negative electrodes, ultimately leading to short circuits and fires. Furthermore, a single polymer material cannot simultaneously achieve high room-temperature ionic conductivity and a high-temperature shut-off effect; gradient polymerization can simultaneously optimize interfacial contact, ion migration kinetics, and thermal response sensitivity. Therefore, developing gradient-polymerized gel polymer electrolytes capable of automatically triggering physical or chemical changes to prevent thermal runaway chain reactions can effectively improve the thermal safety performance of electrolytes. Summary of the Invention

[0004] Based on the above technical background, this invention provides a method for preparing a high-temperature and high-pressure resistant solid electrolyte membrane with a gradient structure and its application in high-safety lithium / sodium batteries. This solid electrolyte membrane uses a porous polymer membrane substrate as its basic framework, which can effectively improve the tensile strength of the polymer electrolyte. Photoinitiated vinyl ether polymers exhibit good interfacial compatibility and long-term stability, while further enhancing the mechanical strength of the polymer membrane. The polymer-type deep eutectic electrolyte can maintain high lithium-ion conductivity while instantaneously copolymerizing with thermosetting polymer monomers in situ during thermal runaway, drastically increasing its resistance or cutting off ion pathways, thereby instantly suppressing current and preventing thermal runaway chain reactions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a high-temperature, high-pressure resistant solid electrolyte membrane with a gradient structure includes the following steps:

[0007] Step 1: Drop heat-responsive polymer precursor slurry onto a porous polymer membrane substrate until the slurry is uniformly dispersed on the porous polymer membrane substrate to obtain a prepolymer membrane; at room temperature, the heat-responsive polymer precursor slurry inside the porous structure of the prepolymer membrane remains in a liquid state, and at high temperature, thermally initiated in-situ polymerization will occur to generate a heat-resistant thermosetting polymer insulation layer.

[0008] Step 2: Coat the photoresponsive polymer precursor slurry evenly on the prepolymer film containing the thermally responsive polymer precursor slurry, and irradiate it under ultraviolet light for 5-30 minutes until the outer photoresponsive polymer precursor is fully polymerized to obtain a solid electrolyte membrane.

[0009] The thermally responsive polymer precursor slurry includes a thermosetting polymer monomer, a polymeric deep eutectic electrolyte, and a thermal initiator; the photoresponsive polymer precursor slurry includes a photoresponsive polymer monomer, a polymeric deep eutectic electrolyte, and a photoinitiator.

[0010] The mass ratio of photoresponsive polymer monomers to polymeric deep eutectic electrolyte in the photoresponsive polymer precursor slurry is 1-10:1-20. The photoinitiator is a cationic photoinitiator, and its mass percentage is 0.1%-0.5% of the total mass of the photoresponsive polymer monomers and polymeric deep eutectic electrolyte. The photoinitiator includes diaryliodonium salt, triaryliodonium salt, alkyliodonium salt, and cumeneferrocene hexafluorophosphate.

[0011] Furthermore, the photoresponsive polymer monomer includes one or more of the following polymer monomers: methyl vinyl ether, n-butyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, perfluoroalkyl vinyl ether, perfluorosulfonic acid vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, cyclohexyl vinyl dimethyl ether, 1,4-cyclohexanediethanol divinyl ether, and triethylene glycol divinyl ether. The photoinitiated vinyl ether system exhibits good interfacial compatibility, thermal safety, and high-pressure stability.

[0012] Furthermore, the thermosetting polymer monomer includes one or more of triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, and diallyl bisphenol A thermosetting polymer monomers. The thermosetting polymer polymer, after thermal initiation polymerization, forms a three-dimensional network structure with the polymeric deep eutectic electrolyte through chemical cross-linking. This network structure possesses excellent electronic insulation and high-temperature resistance, capable of instantly cutting off electron transport during thermal runaway, preventing chain reactions of thermal runaway, and preventing short circuits, fires, or even explosions at the positive and negative electrodes, thereby ensuring the thermal safety of the battery. The mass ratio of thermosetting polymer monomer to polymeric deep eutectic electrolyte in the thermally responsive polymer precursor slurry is 1-5:1-10. The thermal initiator is a free radical type thermal initiator, and its mass percentage is 0.1%-0.5% of the total mass of the thermosetting polymer monomer and the polymeric deep eutectic electrolyte.

[0013] Furthermore, the polymer-type deep eutectic electrolyte is prepared by mixing polymer amide monomers and lithium / sodium salts; the molar ratio of polymer amide monomers to lithium / sodium salts is 1:1-20:1.

[0014] Furthermore, the polymer amide monomer includes one or more of N-isopropylacrylamide, N-ethylacrylamide, N-hydroxyethylacrylamide, N,N-dimethylacrylamide, and N,N-diethylacrylamide; the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium nitrate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalate borate, lithium bis(fluoromethanesulfonyl)imide, lithium trifluoroacetate, and lithium trifluoromethanesulfonate; the sodium salt includes one or more of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium nitrate, sodium bis(trifluoromethanesulfonyl)imide, sodium difluorooxalate borate, sodium bis(fluoromethanesulfonyl)imide, sodium trifluoroacetate, and sodium trifluoromethanesulfonate.

[0015] Furthermore, in step one, the porous polymer membrane substrate includes commercial porous polyethylene, porous polypropylene, porous polyethylene / porous polypropylene composite membrane, or porous polymer membrane substrate prepared from one or more of PVDF-HFP, PMMA, PAN, and PEO as raw materials.

[0016] Furthermore, the addition amount of the thermally responsive polymer precursor slurry is 1-5 μL / cm³. 2 The addition amount of photoresponsive polymer precursor slurry is 5-10 μL / cm³. 2 .

[0017] Furthermore, the method for preparing the porous polymer membrane substrate includes the following steps:

[0018] Step 1: Heat and stir the polar solvent and polymer solid particles at 50-70℃ until the particles are completely dissolved to obtain a homogeneous and stable mixed solution for subsequent coating and casting film formation processes; the mass ratio of polymer solid particles is 5%-15%; high temperature can increase the kinetic energy of solvent molecules and weaken the interaction forces between polymer chains, thereby significantly accelerating the dissolution rate;

[0019] Step 2: Add the pore-forming agent to the above mixed solution, continue heating and stirring at 50-70℃ until the solid flocs are completely dissolved, and then continue stirring at room temperature for 12 h to uniformly disperse the polymer molecular chains, forming a thermodynamically stable homogeneous transparent solution, thus obtaining a phase inversion solution; the mass ratio of the mixed solution to the pore-forming agent is 100:1-100:5;

[0020] Step 3: Apply the phase inversion solution to the substrate by casting or coating method, with a thickness of 200-1000 μm. After the polar solvent evaporates naturally, immerse the substrate coated with the phase inversion solution in a water bath for 5-30 minutes. The phase inversion solution undergoes deep phase separation, and the polymer film substrate forms a porous structure.

[0021] Step 4: Remove the polymer membrane substrate from the water bath, soak and wash it with deionized water to thoroughly remove residual solvent and pore-forming agent. First, allow it to air dry naturally at room temperature, then place it in a vacuum oven for final drying to obtain the porous polymer membrane substrate. Adjust the coating thickness of the phase inversion solution to prepare porous polymer membrane substrates of different thicknesses, ranging from 5-50 μm.

[0022] Furthermore, in step 1, the polymer is one or a mixture of PVDF-HFP, PMMA, PAN, and PEO.

[0023] Furthermore, the polar solvent includes one or more of acetonitrile, acetone, and N-methylpyrrolidone, and the pore-forming agent is one or more of water, methanol, ethanol, and isopropanol; the pore-forming agent has good compatibility with the main polar solvent.

[0024] An application of the solid electrolyte membrane prepared by the preparation method described above is disclosed. The solid electrolyte membrane is used in a high-temperature resistant and high-safety solid lithium / sodium battery, wherein the solid lithium / sodium battery includes a positive electrode, a solid electrolyte membrane prepared by the above method, and a negative electrode.

[0025] Lithium-ion battery cathodes include high-nickel layered oxides, lithium-rich manganese-based oxides, lithium iron phosphate, lithium cobalt oxide, or high-voltage nickel-manganese.

[0026] Lithium-ion battery anodes include niobium-based oxides, metallic lithium, graphite, silicon-based materials, or lithium titanate.

[0027] Sodium-ion electrodes include layered oxides, polyanionic compounds, sodium vanadium fluorophosphate, or Prussian blue electrodes.

[0028] Sodium electrode anodes include metallic sodium, hard carbon, niobium-based oxides, or titanium-based oxides.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. The unique porous membrane structure of the porous polymer membrane substrate provides uniform storage and ion conduction space for the subsequently injected polymer-type deep eutectic electrolyte, while also preventing leakage of the liquid slurry applied later and enhancing the mechanical strength of the final electrolyte membrane.

[0031] 2. The photoresponsive polymer electrolyte has a gradient structure that combines rigidity and flexibility. The outer layer of the polymer membrane is made of a highly flexible and elastic vinyl ether polymer with good interfacial compatibility. The internal polymer-type deep eutectic electrolyte also ensures that the porous polymer membrane substrate has high ionic conductivity at room temperature. At high temperature, the inner thermally responsive polymer slurry will undergo in-situ polymerization, constructing a binary gradient structure of flexible photopolymer layer / rigid thermal polymer layer.

[0032] 3. The thermosetting polymer monomer and the polymer-type deep eutectic electrolyte can undergo in-situ thermal polymerization at the moment of thermal runaway, realizing rapid and abrupt shutdown of ion conduction, thereby quickly blocking thermal runaway.

[0033] 4. The coating method used is a mature thin film preparation technology that can be easily integrated into the existing battery roll-to-roll production process, and the industrialization threshold is relatively low.

[0034] 5. The solid electrolyte adopts an integrated process: the three major functions of the separator, solid electrolyte, and safety layer are integrated into a single thin film, which simplifies the battery structure and improves the energy density.

[0035] 6. The components of the porous polymer membrane substrate, pore-forming agent, and polymer-type deep eutectic electrolyte can be flexibly adjusted to meet the needs of different systems such as lithium batteries and sodium batteries.

[0036] 7. The greatest innovation of this invention lies in transforming "passive protection" into "active self-adaptation," and cleverly solving the contradiction between high ionic conductivity and high safety, and good interfacial contact and high mechanical strength through the binary gradient structure design of flexible photopolymer layer / rigid thermopolymer layer and integrated fabrication process. This provides a very promising solution for building the next generation of high-safety, high-energy-density lithium / sodium batteries. Attached Figure Description

[0037] Figure 1 This is a test diagram of the electrochemical window in Example 5;

[0038] Figure 2 This is a graph from Example 5 showing the lithium-ion transference number test.

[0039] Figure 3 This is the high-pressure cycle performance diagram of Example 6;

[0040] Figure 4 This is the conductivity test graph from Example 9. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Example 1:

[0043] This embodiment provides a method for preparing a porous polymer membrane substrate, including the following steps: Step 1: Acetonitrile and PEO polymer solid particles are heated and stirred at 60°C in a mass ratio of 19:1 until the particles are completely dissolved to obtain a mixed solution.

[0044] Step 2: Add 5% water by mass to the above mixed solution as a pore-forming agent, continue heating and stirring at 70°C until the solid flocculation is completely dissolved, and then continue stirring at room temperature for 12 hours to obtain a phase inversion solution.

[0045] Step 3: Apply the phase inversion solution to a glass plate at a thickness of 700 μm using a coater. After the acetonitrile has completely evaporated, immerse the substrate coated with the phase inversion solution in a water bath to achieve deep phase separation, and the polymer film substrate will form a porous structure.

[0046] Step 4: Remove the polymer membrane substrate from the water bath, soak and wash it with deionized water to thoroughly remove residual solvent and pore-forming agent, first air dry it naturally in the air at room temperature until the porous polymer membrane substrate turns white, then place it in a desiccator to evaporate naturally for 6 hours to remove polar solvent, and then place it in a vacuum drying oven at 80°C for 12 hours to obtain the porous polymer membrane substrate.

[0047] Example 2:

[0048] This embodiment provides a method for preparing a porous polymer membrane substrate, including the following steps:

[0049] Step 1: Heat and stir acetonitrile, acetone and PEO and PVDF polymer solid particles at 60°C in a mass ratio of 10:10:1:1 until the particles are completely dissolved to obtain a mixed solution.

[0050] Step 2: Add 2% water and 3% ethanol by mass to the above mixed solution as pore-forming agents, continue heating and stirring at 65°C until the solid flocculation is completely dissolved, and then continue stirring at room temperature for 12 hours to obtain a phase inversion solution.

[0051] Step 3: Apply the phase inversion solution to a glass plate with a coating tool to a depth of 500 μm. After the acetonitrile and acetone have completely evaporated, immerse the substrate coated with the phase inversion solution in a water bath to achieve deep phase separation and form a porous structure in the polymer film substrate.

[0052] Step 4: Remove the polymer membrane substrate from the water bath, soak and wash it with deionized water to thoroughly remove residual solvent and pore-forming agent. First, let it air dry naturally at room temperature. The porous polymer membrane substrate will turn white. Then, place it in a desiccator to evaporate naturally for 10 hours to remove polar solvent. Finally, place it in a vacuum drying oven at 80°C for 12 hours to obtain the porous polymer membrane substrate.

[0053] Example 3:

[0054] This embodiment provides a method for preparing a high-temperature resistant thermally responsive polymer precursor slurry for lithium-ion batteries, comprising the following steps: Step 1: Accurately weigh N-hydroxyethylacrylamide, N,N-dimethylacrylamide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalateborate, and lithium nitrate according to a mass ratio of 6:10:0.5:0.5:0.1, and stir at 60°C and 400 r / min to form a stable and uniform dispersed phase to obtain a polymeric deep eutectic electrolyte. Add 15% by mass of the thermosetting polymer monomers triallyl isocyanurate and triallyl cyanurate (mass ratio 1:1) to this electrolyte. Then, add 0.2% by mass of the thermal initiator azobisisobutyronitrile (AIBN) to the prepared precursor slurry to obtain the thermally responsive polymer precursor slurry. All the above steps are performed in an argon-filled glove box, and the slurry should be stored away from light for no more than 5 hours.

[0055] Example 4:

[0056] This embodiment provides a method for preparing a photoresponsive polymer precursor slurry for lithium-ion batteries, comprising the following steps: Step 1: Accurately weigh N-isopropylacrylamide, lithium bis(trifluoromethanesulfonyl)imide, and lithium tetrafluoroborate in a mass ratio of 15:1:0.1, and stir at 50°C and 300 r / min to form a stable and uniform dispersed phase to obtain a polymeric deep eutectic electrolyte. Then, add 8% by mass of the photoresponsive polymer monomer methyl vinyl ether to this electrolyte. Next, add 0.2% by mass of the photoinitiator diaryliodonium to the prepared precursor slurry to obtain the photoresponsive polymer precursor slurry. All the above steps are performed in an argon-filled glove box, and the slurry should be stored away from light for no more than 5 hours.

[0057] Example 5:

[0058] This embodiment provides a method for preparing a thermally adaptive, gradient-polymerized solid electrolyte membrane for lithium-ion batteries. Step 1: Using the porous polymer membrane prepared in Example 1 as a substrate, the mechanical strength of the composite electrolyte membrane is enhanced. The thermally responsive polymer precursor slurry prepared in Example 3 is precisely and uniformly coated onto the porous polymer membrane substrate at a coating amount of 2 μL / cm³. 2 A composite prepolymer film wetted with the thermally responsive polymer precursor slurry was obtained. Step 2: Secondary coating: The photoresponsive polymer precursor slurry prepared in Example 4 was uniformly coated onto the prepolymer film obtained in the first step, with a coating amount of 8 μL / cm². 2 The thickness is 500 μm. The entire composite membrane is irradiated with ultraviolet light for 5 minutes, resulting in a high-temperature and high-pressure resistant solid electrolyte membrane with a gradient structure.

[0059] Example 6:

[0060] This embodiment provides a method for preparing a solid-state lithium-ion battery using a thermally adaptive, gradient-polymerized solid electrolyte membrane. Lithium metal is used as the negative electrode, the solid electrolyte membrane from Example 5 is used as the electrolyte, and LiNi is used as the electrolyte. 0.8 Co 0.1 Mn 0.1 It serves as the positive electrode for assembling solid-state lithium-ion batteries.

[0061] Example 7:

[0062] This embodiment provides a method for preparing a high-temperature resistant thermoresponsive polymer precursor slurry for sodium-ion batteries, comprising the following steps: Step 1: Accurately weigh N-isopropylacrylamide, N-hydroxyethylacrylamide, N,N-dimethylacrylamide, sodium hexafluorophosphate, sodium difluorooxalate borate, and sodium tetrafluoroborate in a mass ratio of 8:7.6:0.4:0.4:0.4:0.2, and stir at 300 r / min at 50°C to form a stable and uniform dispersed phase to obtain a polymeric deep eutectic electrolyte. Add 12% by mass of the thermosetting polymer monomers diallyl phthalate and diallyl bisphenol A (mass ratio 2:3) to this electrolyte. Then, add 0.5% by mass of a thermal initiator to the prepared precursor slurry to obtain a photoresponsive polymer precursor slurry. All the above steps are performed in an argon-filled glove box, and the slurry should be stored away from light for no more than 5 hours.

[0063] Example 8:

[0064] This embodiment provides a method for preparing a photoresponsive polymer precursor slurry for sodium-ion batteries, comprising the following steps: Step 1: Accurately weigh N-ethylacrylamide, sodium bis(trifluoromethanesulfonyl)imide, and sodium trifluoroacetate in a mass ratio of 14:1:0.1, and stir at 250 r / min at 55°C until a stable and uniform dispersed phase is formed to obtain a polymeric deep eutectic electrolyte. Then, add 7% by mass of the photoresponsive polymer monomers isobutyl vinyl ether and perfluoroalkyl vinyl ether (mass ratio 1:1) to the electrolyte. Next, add 0.1% by mass of the photoinitiator triarylthionium hexafluoroantimonate to the prepared precursor slurry to obtain the photoresponsive polymer precursor slurry. All the above steps are performed in an argon-filled glove box, and the slurry should be stored away from light for no more than 5 hours.

[0065] Example 9:

[0066] This embodiment provides a method for preparing a thermally adaptive, gradient-polymerized solid electrolyte membrane for sodium-ion batteries, including the following steps: Step 1: Using the porous polymer membrane prepared in Example 2 as a substrate to enhance the mechanical strength of the composite electrolyte membrane. The thermally responsive polymer precursor slurry prepared in Example 7 is precisely and uniformly coated onto the porous polymer membrane substrate at a coating amount of 3 μL / cm³. 2 A composite prepolymer film wetted with the thermally responsive polymer precursor slurry was obtained. Step 2: Secondary coating: The photoresponsive polymer precursor slurry prepared in Example 8 was uniformly coated onto the prepolymer film obtained in the first step, with a coating amount of 8 μL / cm². 2 The thickness is 700 μm. The entire composite membrane was irradiated with ultraviolet light for 5 minutes, resulting in a high-temperature and high-pressure resistant solid electrolyte membrane with a gradient structure.

[0067] Example 10:

[0068] This embodiment provides a method for preparing a solid-state sodium-ion battery using a thermally adaptive, gradient-polymerized solid electrolyte membrane. Sodium metal is used as the negative electrode, the solid electrolyte membrane from Example 9 is used as the electrolyte, and NaNi is used as the electrolyte. 1 / 3 Fe 1 / 3 Mn 1 / Using 3O2 as the positive electrode, a solid-state sodium-ion battery is assembled.

[0069] As can be seen from the attached diagram in the instruction manual:

[0070] like Figure 1 As shown in Example 5, the high-temperature and high-pressure resistant solid electrolyte membrane with a gradient structure exhibits an electrochemical window >4.5V, which can improve the problem of instability at the interface between the high-voltage cathode and the electrolyte, and has the potential to be applied to next-generation high-energy-density and high-safety solid-state batteries. Furthermore, as... Figure 2 As shown, the high-temperature and high-pressure resistant solid electrolyte membrane with a gradient structure prepared in Example 5 exhibits a high lithium-ion transference number, significantly reducing concentration polarization within the electrolyte. This electrolyte enables highly efficient lithium-ion migration and provides fast charging capability. Figure 3 As shown, the high-voltage performance of the battery in Example 6 was further evaluated. The solid electrolyte membrane exhibited good high-voltage cycling stability under a charge-discharge mechanism of 4.65V / 0.5C. This indicates that the gradient structure design of the electrolyte not only effectively suppresses electrolyte decomposition and harmful interface growth at the high-voltage positive electrode, but also maintains good interfacial compatibility with the lithium metal anode, giving it the potential to simultaneously possess high voltage (high energy density), long cycle life (interfacial stability), and high safety (dendritic suppression). Figure 4 As shown, the sodium-ion battery electrolyte membrane based on this gradient structure design concept has a high ionic conductivity of 0.11 mS / cm, proving that this gradient structure design concept is a universal solution for high-performance electrolyte structures.

[0071] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a high-temperature, high-pressure resistant solid electrolyte membrane with a gradient structure, characterized in that, Includes the following steps: Step 1: Drop a heated polymer precursor slurry onto a porous polymer membrane substrate until the slurry is uniformly dispersed on the porous polymer membrane substrate to obtain a prepolymer membrane; Step 2: The photoresponsive polymer precursor slurry is uniformly coated on the prepolymer film, and the photoinitiation process is carried out until the outer photoresponsive polymer precursor slurry is fully polymerized to obtain a solid electrolyte membrane. The thermally responsive polymer precursor slurry includes a thermosetting polymer monomer, a polymeric deep eutectic electrolyte, and a thermal initiator; the photoresponsive polymer precursor slurry includes a photoresponsive polymer monomer, a polymeric deep eutectic electrolyte, and a photoinitiator.

2. The preparation method according to claim 1, characterized in that: The mass ratio of photoresponsive polymer monomers to polymeric deep eutectic electrolyte in the photoresponsive polymer precursor slurry is 1-10:1-20, and the mass percentage of the photoinitiator is 0.1%-0.5% of the total mass of the photoresponsive polymer monomers and polymeric deep eutectic electrolyte; the mass ratio of thermosetting polymer monomers to polymeric deep eutectic electrolyte in the thermally responsive polymer precursor slurry is 1-5:1-10, and the mass percentage of the thermal initiator is 0.1%-0.5% of the total mass of the thermosetting polymer monomers and polymeric deep eutectic electrolyte.

3. The preparation method according to claim 1, characterized in that: The thermosetting polymer monomer includes one or more of triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, and diallyl bisphenol A; the photoresponsive polymer monomer includes one or more of methyl vinyl ether, n-butyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, perfluoroalkyl vinyl ether, perfluorosulfonic acid vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, cyclohexyl vinyl dimethyl ether, 1,4-cyclohexanediethanol divinyl ether, and triethylene glycol divinyl ether.

4. The preparation method according to claim 1, characterized in that: The polymer-type deep eutectic electrolyte is prepared by mixing polymer amide monomers and lithium / sodium salts; the molar ratio of polymer amide monomers to lithium / sodium salts is 1:1-20:

1.

5. The preparation method according to claim 4, characterized in that: The polymer amide monomer includes one or more of N-isopropylacrylamide, N-ethylacrylamide, N-hydroxyethylacrylamide, N,N-dimethylacrylamide, and N,N-diethylacrylamide; the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium nitrate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalateborate, lithium bis(fluorosulfonyl)imide, lithium trifluoroacetate, and lithium trifluoromethanesulfonate; the sodium salt includes one or more of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium nitrate, sodium bis(trifluoromethanesulfonyl)imide, sodium difluorooxalateborate, sodium bis(fluorosulfonyl)imide, sodium trifluoroacetate, and sodium trifluoromethanesulfonate.

6. The preparation method according to claim 1, characterized in that: The porous polymer membrane substrate includes commercial porous polyethylene, porous polypropylene, porous polyethylene / polypropylene composite membrane, or porous polymer membrane substrate prepared from one or more of PVDF-HFP, PMMA, PAN, and PEO as raw materials.

7. The preparation method according to claim 1, characterized in that: The addition amount of the thermally responsive polymer precursor slurry is 1-5 μL / cm³. 2 The addition amount of photoresponsive polymer precursor slurry is 5-10 μL / cm³. 2 .

8. The preparation method according to claim 1, characterized in that: The method for preparing the porous polymer membrane substrate includes the following steps: Step 1: Heat and stir the polar solvent and polymer solid particles at 50-70℃ until the particles are completely dissolved to obtain a mixed solution; the mass percentage of polymer solid particles is 5%-15%. Step 2: Add the pore-forming agent to the above mixed solution, continue heating and stirring to dissolve, and obtain a phase inversion solution; the mass ratio of the mixed solution to the pore-forming agent is 100:1-100:5; Step 3: Coat the phase inversion solution onto the substrate. After the polar solvent evaporates naturally, immerse the substrate coated with the phase inversion solution in a water bath to achieve deep phase separation. Then wash and dry to obtain a porous polymer membrane substrate.

9. The preparation method according to claim 8, characterized in that: The polar solvent includes one or more of acetonitrile, acetone, and N-methylpyrrolidone, and the pore-forming agent includes one or more of water, methanol, ethanol, and isopropanol.

10. The application of a solid electrolyte membrane prepared by the preparation method according to any one of claims 1-9, characterized in that: The solid electrolyte membrane is used in high-temperature resistant, high-safety solid lithium / sodium batteries.

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