Multifunctional polymer electrolyte membrane and preparation method and application thereof

Abstract

The invention belongs to the technical field of electrolyte materials, and discloses a multifunctional polymer electrolyte membrane and a preparation method and application thereof. The preparation method comprises the following steps: mixing a substrate material, a self-healing material, a conductive material, a reinforcing material and a solvent to obtain a composite solution; the composite solution is subjected to electrostatic spinning, a membrane material obtained through electrostatic spinning is subjected to heat treatment, and a nanofiber membrane is obtained; and coating the nanofiber membrane with the solution of the thermal response material, and carrying out drying treatment to obtain the multifunctional polymer electrolyte membrane. The multifunctional polymer electrolyte membrane prepared by the invention not only has good ionic conductivity, but also has the characteristics of self-healing, thermal response and the like, can effectively improve the stability and durability of a flexible electronic device, adapts to different working environments, and has wide application prospects. The requirements of novel battery systems such as flexible electronic devices, wearable equipment and flexible energy storage devices can be met, and further development of the flexible electronic technology is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolyte materials, and in particular to a multifunctional polymer electrolyte membrane and a preparation method and application thereof. Background Art

[0002] Flexible electronic devices require electrolyte membranes with better mechanical properties, conductivity, and adaptability to the external environment (such as temperature changes, mechanical pressure, etc.). With the rapid development of flexible electronic technology, traditional rigid electrolyte membranes are gradually unable to meet the performance requirements of flexible electrolyte membrane materials. For example, the self-healing ability of traditional rigid electrolyte membranes is insufficient, which makes it easy for the electrolyte membrane to rupture or deform under the action of external forces, thereby causing the battery performance to decline; the thermal response performance of traditional rigid electrolyte membranes is poor, which makes it easy for the membrane material to deform or fail in high temperature environments, thereby affecting the stability and safety of the equipment; the application of traditional rigid electrolyte membranes in flexible electronic devices is limited, and it is difficult to meet the long-term stable working requirements.

[0003] Therefore, developing an electrolyte membrane with multifunctional properties that can meet the needs of flexible electronic devices has become a technical bottleneck in the current battery material field. Summary of the invention

[0004] The purpose of the present invention is to provide a multifunctional polymer electrolyte membrane and a preparation method and application thereof, so as to solve the problem that the existing rigid electrolyte membrane cannot meet the performance requirements of flexible electronic devices.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a multifunctional polymer electrolyte membrane, comprising the following steps:

[0007] The base material, the self-healing material, the conductive material, the reinforcing material and the solvent are mixed to obtain a composite solution; the composite solution is subjected to electrostatic spinning, and the membrane material obtained by electrostatic spinning is subjected to heat treatment to obtain a nanofiber membrane;

[0008] The solution of the thermal response material is coated on the nanofiber membrane and dried to obtain a multifunctional polymer electrolyte membrane;

[0009] Wherein, the substrate material includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyetheretherketone, polylactic acid, polyethersulfone, and polymethyl methacrylate;

[0010] The self-healing material includes one or more of polydisulfide, polyurea, polyurethane, polyethylene glycol diacrylate, polyacrylic acid, polymethacrylate, and polylactic acid-glycolic acid copolymer;

[0011] The conductive material includes a blend of a lithium salt and an ionic liquid;

[0012] The reinforcing material includes one or more of graphene, carbon nanotubes, graphene oxide, carbon black, nano silicon fiber, and nano silicon dioxide;

[0013] The thermal response material includes a blend of a polymer material and an inorganic lithium salt.

[0014] Preferably, in the preparation method, in the conductive material, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide, and the ionic liquid includes one or more of imidazole ionic liquids, pyridine ionic liquids, and phosphate ionic liquids.

[0015] Preferably, in the preparation method, the imidazole ionic liquid includes one or more of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide;

[0016] The pyridinium ionic liquid includes one or more of 1-butylpyridinium tetrafluoroborate, 1-ethylpyridinium hexafluorophosphate, 1-propylpyridinium bis(trifluoromethylsulfonyl)imide, 1-butylpyridinium hexafluorophosphate, 1-methylpyridinium tetrafluoroborate, 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide, 1-octylpyridinium hexafluorophosphate, 1-propylpyridinium tetrafluoroborate, 1-phenylpyridinium bis(trifluoromethylsulfonyl)imide, and 1-methylpyridinium hexafluorophosphate;

[0017] The phosphate ionic liquid includes one or more of 1-butyl-3-methylimidazolium trimethyl (trifluoromethylsulfonyl) phosphate, 1-ethyl-3-methylimidazolium trimethyl phosphate, and 1-butyl-3-methylimidazolium triethyl phosphate.

[0018] Preferably, in the preparation method, in the composite solution, the mass concentration of the base material is 12-20%, the mass concentration of the self-healing material is 2-5%, the mass concentration of the conductive material is 8-15%, and the mass concentration of the reinforcing material is 1-5%.

[0019] Preferably, in the preparation method, the electrospinning conditions include: voltage of 15-20 kV, working distance of 12-20 cm, injection rate of 0.3-1 mL / h, temperature of 20-30° C., and humidity of 30-50%.

[0020] Preferably, in the preparation method, the heat treatment conditions include: temperature of 80 to 120° C. and time of 0.5 to 2 h.

[0021] Preferably, in the preparation method, in the thermal response material, the polymer material includes one or more of polyvinyl alcohol, hydroxypropyl methylcellulose, and chitosan, and the inorganic lithium salt includes one or more of lithium carbonate, lithium chloride, lithium hydroxide, lithium nitrate, lithium sulfate, lithium dihydrogen phosphate, and lithium bicarbonate;

[0022] In the thermal response material, the mass ratio of the polymer material to the inorganic lithium salt is 4:1 to 0.5:1.

[0023] Preferably, in the preparation method, the drying treatment conditions include: a temperature of 50 to 80° C. and a time of 0.5 to 1 h;

[0024] The coating amount of the thermal response material on the nanofiber membrane is 0.5-1 mg / cm 2 .

[0025] The invention also provides a multifunctional polymer electrolyte membrane.

[0026] The invention also provides an application of a multifunctional polymer electrolyte membrane in a flexible electronic device.

[0027] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0028] The multifunctional polymer electrolyte membrane prepared by the present invention, by adding functional materials such as self-healing materials, conductive materials, reinforcing materials, and thermal response materials, not only has good ionic conductivity, but also has the characteristics of self-healing and thermal response, which can effectively improve the stability and durability of flexible electronic devices, adapt to different working environments, and especially maintain stable performance under conditions such as temperature changes and mechanical pressure. This multifunctional polymer electrolyte membrane is not only suitable for lithium-ion batteries, but also has a wide range of application prospects, can meet the needs of new battery systems such as flexible electronic devices, wearable devices, and flexible energy storage devices, and promote the further development of flexible electronic technology. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a multifunctional polymer electrolyte membrane, comprising the following steps:

[0030] The base material, the self-healing material, the conductive material, the reinforcing material and the solvent are mixed to obtain a composite solution; the composite solution is subjected to electrostatic spinning, and the membrane material obtained by electrostatic spinning is subjected to heat treatment to obtain a nanofiber membrane;

[0031] The solution of the thermal response material is coated on the nanofiber membrane and dried to obtain a multifunctional polymer electrolyte membrane;

[0032] Wherein, the substrate material includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyetheretherketone, polylactic acid, polyethersulfone, and polymethyl methacrylate;

[0033] The self-healing material includes one or more of polydisulfide, polyurea, polyurethane, polyethylene glycol diacrylate, polyacrylic acid, polymethacrylate, and polylactic acid-glycolic acid copolymer;

[0034] The conductive material includes a blend of a lithium salt and an ionic liquid;

[0035] The reinforcing material includes one or more of graphene, carbon nanotubes, graphene oxide, carbon black, nano silicon fiber, and nano silicon dioxide;

[0036] The thermal response material includes a blend of a polymer material and an inorganic lithium salt.

[0037] In the present invention, the base material preferably includes multiple materials selected from polyvinylidene fluoride, polyacrylonitrile, polyetheretherketone, polylactic acid, polyethersulfone, and polymethyl methacrylate, further preferably includes multiple materials selected from polyvinylidene fluoride, polyacrylonitrile, and polymethyl methacrylate, and more preferably includes two materials selected from polyvinylidene fluoride and polyacrylonitrile.

[0038] In the present invention, when the base material is preferably of multiple types, the ratio between the types is not limited, and the schemes well known in the art can be adopted.

[0039] In the present invention, in the composite solution, the mass concentration of the base material is preferably 12 to 20%, more preferably 15 to 18%, and even more preferably 16 to 17%.

[0040] In the present invention, the self-healing material preferably includes one or more of polydisulfide, polyurethane, polyethylene glycol diacrylate, polymethacrylate, polylactic acid-glycolic acid copolymer, further preferably includes polydisulfide, polyurethane, polyethylene glycol diacrylate, polymethacrylate or polylactic acid-glycolic acid copolymer, more preferably includes polydisulfide, polyethylene glycol diacrylate or polylactic acid-glycolic acid copolymer.

[0041] In the present invention, when the self-healing material is preferably of multiple types, the ratio between the types is not limited, and the schemes well known in the art can be adopted.

[0042] In the present invention, in the composite solution, the mass concentration of the self-healing material is preferably 2-5%, more preferably 3-4%, and even more preferably 3.2-3.6%.

[0043] In the present invention, the lithium salt in the conductive material preferably includes lithium hexafluorophosphate (LiPF 6 ), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium bisfluorosulfonyl imide, further preferably including lithium hexafluorophosphate, lithium bistrifluoromethanesulfonyl imide or lithium bisfluorosulfonyl imide, more preferably including lithium hexafluorophosphate or lithium bistrifluoromethanesulfonyl imide.

[0044] In the present invention, when the lithium salt is preferably of multiple types, the ratio between the various types is not limited, and the schemes well known in the art can be used.

[0045] In the present invention, in the conductive material, the ionic liquid preferably includes one or more of imidazole ionic liquids, pyridine ionic liquids, and phosphate ionic liquids, further preferably includes imidazole ionic liquids, pyridine ionic liquids or phosphate ionic liquids, and more preferably includes imidazole ionic liquids.

[0046] In the present invention, the imidazolium ionic liquid preferably includes 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF 4 ]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TFSI]), 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([PMIM][TFSI]), further preferably including 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, more preferably including 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate or 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

[0047] In the present invention, the pyridine ionic liquid preferably includes 1-butylpyridinium tetrafluoroborate ([BPY][BF 4]), 1-ethylpyridine hexafluorophosphate, 1-propylpyridine bis (trifluoromethylsulfonyl) imide, 1-butylpyridine hexafluorophosphate, 1-methylpyridine tetrafluoroborate, 1-hexylpyridine bis (trifluoromethylsulfonyl) imide, 1-octylpyridine hexafluorophosphate, 1-propylpyridine tetrafluoroborate, 1-phenylpyridine bis (trifluoromethylsulfonyl) imide, 1-methylpyridine hexafluorophosphate one or more, further preferably including 1-butylpyridine tetrafluoroborate, 1-ethylpyridine hexafluorophosphate, 1-butylpyridine hexafluorophosphate, 1-methylpyridine tetrafluoroborate, 1-propylpyridine tetrafluoroborate, 1-methylpyridine hexafluorophosphate one or more, more preferably 1-butylpyridine tetrafluoroborate.

[0048] In the present invention, the phosphate ionic liquid preferably includes one or more of 1-butyl-3-methylimidazolium trimethyl (trifluoromethylsulfonyl) phosphate, 1-ethyl-3-methylimidazolium trimethyl phosphate, and 1-butyl-3-methylimidazolium triethyl phosphate, and further preferably includes 1-butyl-3-methylimidazolium trimethyl (trifluoromethylsulfonyl) phosphate and / or 1-ethyl-3-methylimidazolium trimethyl phosphate, and more preferably 1-butyl-3-methylimidazolium trimethyl (trifluoromethylsulfonyl) phosphate.

[0049] In the present invention, when the ionic liquid is preferably of multiple types, the ratio between the various types is not limited, and the schemes well known in the art can be used.

[0050] In the present invention, in the conductive material, the mass ratio of the lithium salt to the ionic liquid is preferably 2:1 to 1:2, more preferably 3:2 to 1:1, and more preferably 1:1.

[0051] In the present invention, in the composite solution, the mass concentration of the conductive material is preferably 8 to 15%, more preferably 8 to 12%, and even more preferably 10 to 12%.

[0052] In the present invention, the reinforcing material preferably includes one or more of graphene, carbon nanotubes, graphene oxide, and nano-silicon dioxide, further preferably includes graphene, carbon nanotubes, graphene oxide, or nano-silicon dioxide, and more preferably includes graphene or graphene oxide.

[0053] In the present invention, when the reinforcing material is preferably of multiple types, the ratio between the various types is not limited, and the schemes well known in the art can be adopted.

[0054] In the present invention, in the composite solution, the mass concentration of the reinforcing material is preferably 1 to 5%, more preferably 2 to 4%, and even more preferably 3 to 4%.

[0055] In the present invention, the solvent preferably includes one or more of ethanol, N,N-dimethylformamide, N,N-dimethylacetamide, trifluoroethanol, and butyl acetate, further preferably includes N,N-dimethylformamide, N,N-dimethylacetamide, trifluoroethanol or butyl acetate, and more preferably includes N,N-dimethylformamide or N,N-dimethylacetamide.

[0056] In the present invention, when the solvent is preferably a plurality of types, the ratio between the various types is not limited, and a solution well known in the art can be used.

[0057] In the present invention, the preparation scheme of the composite solution preferably includes the following steps:

[0058] The base material is mixed with a solvent to obtain a basic solution; the self-healing material, the conductive material and the reinforcing material are added to the basic solution and ultrasonically mixed to obtain a composite solution.

[0059] In the present invention, the conditions for mixing the base material and the solvent are not limited, as long as they are mixed uniformly.

[0060] In the present invention, the time of the mixed ultrasound is preferably 20 to 30 min, more preferably 25 to 30 min, and more preferably 28 to 30 min.

[0061] In the present invention, the conditions for electrospinning include: the voltage is preferably 15-20 kV, more preferably 15-18 kV, and more preferably 16-17 kV; the working distance is preferably 12-20 cm, more preferably 12-16 cm, and more preferably 14-15 cm; the injection rate is preferably 0.3-1 mL / h, more preferably 0.4-0.7 mL / h, and more preferably 0.5-0.6 mL / h; the temperature is preferably 20-30°C, more preferably 22-27°C, and more preferably 24-26°C; the humidity is preferably 30-50%, more preferably 35-45%, and more preferably 38-42%.

[0062] In the present invention, the heat treatment conditions include: the temperature is preferably 80-120°C, more preferably 90-110°C, more preferably 100-110°C; the time is preferably 0.5-2h, more preferably 1-2h, more preferably 1.5-2h.

[0063] In the present invention, in the thermal response material, the polymer material preferably includes one or more of polyvinyl alcohol, hydroxypropyl methylcellulose, and chitosan, further preferably includes polyvinyl alcohol, hydroxypropyl methylcellulose or chitosan, and more preferably includes polyvinyl alcohol.

[0064] In the present invention, when the polymer material is preferably of multiple types, the ratio between the types is not limited and the schemes well known in the art can be adopted.

[0065] In the present invention, in the thermally responsive material, the inorganic lithium salt preferably includes one or more of lithium carbonate, lithium chloride, lithium hydroxide, lithium nitrate, lithium sulfate, lithium dihydrogen phosphate, and lithium bicarbonate, and further preferably includes one or more of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium bicarbonate, and more preferably is lithium carbonate.

[0066] In the present invention, in the thermally responsive material, the mass ratio of the polymer material to the inorganic lithium salt is preferably 4:1 to 0.5:1, more preferably 1:1 to 0.5:1, and more preferably 0.8:1 to 0.6:1.

[0067] In the present invention, in the solution of the thermally responsive material, the solvent preferably includes one or more of water, ethanol, ethylene glycol, isopropanol, dimethyl sulfoxide, and trifluoroethanol, further preferably includes one or more of water, ethanol, and trifluoroethanol, and more preferably is a mixture of water and ethanol.

[0068] In the present invention, when the solvents in the solution of the thermally responsive material are preferably multiple, the ratio between the various types is not limited, and the schemes well known in the art can be used.

[0069] In the present invention, in the solution of the thermally responsive material, the mass concentration of the polymer material is preferably 4 to 12%, more preferably 6 to 10%, and even more preferably 8 to 10%.

[0070] In the present invention, the method for preparing the solution of the thermal response material is not limited, and it only needs to be mixed uniformly.

[0071] In the present invention, the coating amount of the thermal response material on the nanofiber membrane is preferably 0.5 to 1 mg / cm 2 , more preferably 0.6 to 0.9 mg / cm 2 , more preferably 0.7 to 0.8 mg / cm 2 .

[0072] In the present invention, the drying treatment conditions include: the temperature is preferably 50-80°C, more preferably 50-70°C, more preferably 55-60°C; the time is preferably 0.5-1h, more preferably 30-45min, more preferably 35-40min.

[0073] The invention also provides a multifunctional polymer electrolyte membrane.

[0074] The invention also provides an application of a multifunctional polymer electrolyte membrane in a flexible electronic device.

[0075] In the present invention, the application method is not limited, and any method well known in the art may be used.

[0076] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0077] Example 1

[0078] This embodiment provides a method for preparing a multifunctional polymer electrolyte membrane, comprising the following steps:

[0079] The substrate material is polyvinylidene fluoride (PVDF, weight average molecular weight 5.3×10 5 g / mol, Arkema, brand Kynar 761) and polyacrylonitrile (PAN, weight average molecular weight 1.5×10 5 g / mol, Sigma-Aldrich, CAS No. 25014-41-9) was dissolved in N,N-dimethylformamide (DMF) solvent at a mass ratio of 1:3 and stirred evenly to obtain a basic solution;

[0080] Polydisulfide (PDS, disulfide cross-linked polymer, weight average molecular weight 2.5×10 4 g / mol, TCI Chemicals, brand DS1001) as self-healing material, lithium salt LiPF 6 A mixture of lithium salt (purity ≥ 99.5%, Merck KGaA, CAS No. 21324-40-3) and ionic liquid [EMIM] [TFSI] (purity ≥ 99%, IoLiTec GmbH, brand EMIM-TFSI, lithium salt and ionic liquid mass ratio 1:1) as conductive material, graphene (Graphene, average number of layers 3 to 5, specific surface area 120m 2 / g, manufacturer XG Sciences, brand Graphene Nanoplatelets Grade H) as a reinforcing material, the concentration of the base material is 15wt%, the concentration of the self-healing material is 3wt%, the concentration of the conductive material is 10wt%, the concentration of the reinforcing material is 2wt%, and the mixture is evenly mixed, and an ultrasonic treatment device (power 200 W, frequency 40 kHz) is used for ultrasonic treatment for 20 min to ensure that all components are completely dispersed to obtain a composite solution;

[0081] The composite solution was electrospun, and the electrospinning parameters were set as follows: voltage 17 kV, working distance 15 cm, injection rate 0.6 mL / h, temperature 25°C, humidity 40%, to obtain a spinning membrane; the spinning membrane was heat treated at 120°C for 2 h to obtain a nanofiber membrane with a porosity of 45% and a pore size distribution of 200-300 nm;

[0082] Prepare polyvinyl alcohol (PVA, weight average molecular weight 1.2×10 5 ~1.3×10 5 g / mol, Sigma-Aldrich, CAS No.9002-89-5), lithium carbonate (Li 2 CO 3 , particle size 5 μm) and a water-ethanol mixed solution (70:30 v / v) of a thermal response material solution, PVA concentration of 10 wt%, Li 2 CO 3 The concentration is 15wt%, and stirred at 80℃ for 2h to ensure complete dissolution and uniform dispersion;

[0083] The thermal response material solution was coated on the surface of the nanofiber membrane by a casting coating method. The coating amount of the thermal response material was 0.8 mg / cm 2 ; The coated membrane was dried at 60°C for 30 minutes to obtain a multifunctional polymer electrolyte membrane.

[0084] Test Example 1

[0085] (1) Ionic conductivity

[0086] Electrochemical Impedance Spectroscopy (EIS) was used to measure the ionic conductivity. Test conditions: room temperature (25°C) and high temperature (50°C); test equipment: impedance analyzer, frequency range 10 6 Hz~10 - 2 Hz. Calculation formula: σ=R×AL, σ: ion conductivity (S / cm), L: membrane thickness (cm); R: impedance (Ω); A: electrode area (cm 2 ). Reference standard: ASTM E491-20: Test method for electrical conductivity of ion-conductive materials.

[0087] The test showed that the ionic conductivity of the multifunctional polymer electrolyte membrane obtained in Example 1 at room temperature (25°C) was 2.1×10 -3 S / cm, and the ionic conductivity at 50°C is 3.5×10 -3 S / cm, indicating that it has good ion migration ability, and the ion conductivity is significantly improved with increasing temperature.

[0088] (2) Mechanical properties

[0089] Tensile strength and elongation at break: measured using a universal testing machine (such as Instron 3365), the film sample is cut into a standard dumbbell shape (refer to ASTM D638), the test speed is 10 mm / min, and the force value and elongation at break are recorded.

[0090] Fatigue resistance: Perform 100 bending tests (angle 90°) using a repeated bending tester to simulate long-term use conditions; retest the tensile strength after bending and calculate the retention rate. Reference standard: ASTM D882-18: "Standard Test Method for Tensile Properties of Films".

[0091] After testing, the multifunctional polymer electrolyte membrane obtained in Example 1 has a tensile strength of 60 MPa and an elongation at break of 30%. After 100 bending cycles, the anti-fatigue performance is excellent, with a tensile strength retention rate of 92% and an elongation at break retention rate of 88%.

[0092] (3) Self-healing performance

[0093] The film was artificially scratched under a microscope, and the scratch depth was about 50% of the film thickness; the film was placed in a 100°C environment, and the degree of crack closure was observed every 10 minutes, and the self-healing efficiency η = (initial scratch width - scratch width after healing) × 100% was calculated, referring to the standard: ISO 19252-08: "Test methods for self-healing materials".

[0094] The test showed that the multifunctional polymer electrolyte membrane obtained in Example 1 had excellent self-healing performance. After 30 minutes, the self-healing efficiency reached 92%.

[0095] (4) Thermal response performance

[0096] Use a dynamic mechanical analyzer (DMA) to test the thermal response characteristics of the film. Place the film in a temperature-controlled environment (temperature range 20-85°C), record the dimensional change of the film, calculate the coefficient of thermal expansion (CTE), and ensure that the dimensional change rate of the film is less than 3%. Reference standard: ASTM E831-19: Test method for coefficient of thermal expansion.

[0097] According to tests, the multifunctional polymer electrolyte membrane obtained in Example 1 has a size change of less than 3% within a temperature range of 30 to 80°C.

[0098] (5) Battery performance

[0099] Li|LiFePO 4 Battery preparation process:

[0100] (5.1) Prepare battery materials, including: positive electrode material LiFePO 4 (particle size 5 μm), negative electrode material metal lithium (thickness 50 μm), electrolyte membrane is the multifunctional polymer electrolyte membrane of Example 1, conductive agent is conductive carbon black (SuperP), binder is polyvinylidene fluoride (PVDF), solvent is N-methylpyrrolidone (NMP);

[0101] (5.2) Positive electrode preparation: LiFePO 4 : Conductive carbon black: PVDF = 80:10:10 mass ratio is mixed, and an appropriate amount of NMP is added and stirred evenly to form a viscous positive electrode slurry; the positive electrode slurry is coated on the aluminum foil current collector with a thickness of 50 μm and dried at 80°C for 12 hours;

[0102] (5.3) Using the electrolyte membrane in Example 1 as the diaphragm material, cut it to match the size of the electrode;

[0103] (5.4) The positive electrode (LiFePO 4 Coated aluminum foil), electrolyte membrane, and negative electrode (metal lithium) are stacked in sequence and sealed in a vacuum packaging machine to form a standard button battery (CR2032); if liquid electrolyte assistance is required, 1M LiPF 6 A mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio 1:1) was prepared; after assembly, the battery was formed, charged to 3.8V at a rate of 0.1C, and discharged to 2.0V, repeated 3 times at 25°C;

[0104] Cycle stability: Use a constant current charge and discharge device (such as the LAND battery test system) to test the battery charge and discharge cycle 100 times at a rate of 0.5C, and record the capacity retention rate;

[0105] Rate performance: Test the discharge specific capacity at different rates (0.1C, 0.5C, 1C, 3C), reference standard: IEC61960-3: "Capacity and efficiency test methods for lithium-ion batteries".

[0106] After testing, the initial capacity of the battery prepared with the multifunctional polymer electrolyte membrane obtained in Example 1 is 160mAh / g, and the capacity retention rate is 96% after 100 cycles; the discharge specific capacities at different rates (0.1C, 0.5C, 1C, 3C) are 160mAh / g, 155mAh / g, 148mAh / g and 135mAh / g, respectively, indicating that the electrolyte membrane has good ion migration ability and electrochemical stability, and exhibits excellent rate performance.

[0107] Example 2

[0108] This embodiment provides a method for preparing a multifunctional polymer electrolyte membrane, comprising the following steps:

[0109] The base material polyethersulfone (PES, weight average molecular weight 5.8×10 4 g / mol) and polyacrylonitrile (PAN, weight average molecular weight 1.5×10 5 g / mol) was dissolved in N,N-dimethylacetamide (DMAc) solvent at a mass ratio of 2:3 and stirred evenly to obtain a basic solution;

[0110] Polyethylene glycol diacrylate (PEGDA, weight average molecular weight 700 g / mol) as a self-healing material, lithium salt LiTFSI and ionic liquid [BMIM][PF] were added to the base solution in sequence. 6 ] (lithium salt and ionic liquid mass ratio 2: 1) as a conductive material, graphene oxide (GO, manufacturer Sigma-Aldrich, brand 763705) as a reinforcing material, the concentration of the base material is 18wt%, the concentration of the self-healing material is 2wt%, the concentration of the conductive material is 15wt%, the concentration of the reinforcing material is 3wt%, the mixture is evenly mixed, and an ultrasonic treatment device (power 200W, frequency 40kHz) is used for ultrasonic treatment for 30min to ensure that all components are completely dispersed to obtain a composite solution;

[0111] The composite solution was electrospun, and the electrospinning parameters were set as follows: voltage 16 kV, working distance 14 cm, injection rate 0.5 mL / h, temperature 25°C, humidity 40%, to obtain a spinning membrane; the spinning membrane was heat treated at 100°C for 1 h to obtain a nanofiber membrane with a porosity of 50% and a pore size distribution of 150 to 250 nm;

[0112] Prepare hydroxypropyl methylcellulose (HPMC, manufacturer Sigma-Aldrich, brand H7509), lithium carbonate (Li 2 CO 3 , particle size 5 μm) and a thermal response material solution of a deionized water-ethanol mixed solvent (deionized water: ethanol = 1: 1 v / v), HPMC concentration is 8wt%, Li 2 CO 3 The concentration is 10wt%;

[0113] The thermal response material solution was sprayed on the surface of the nanofiber membrane. The coating amount of the thermal response material was 0.7 mg / cm 2 ; The coated membrane was dried at 50°C for 45 minutes to obtain a multifunctional polymer electrolyte membrane.

[0114] Test Example 2

[0115] The performance of the multifunctional polymer electrolyte membrane obtained in Example 2 was tested by the test method of Test Example 1. It can be found that the ionic conductivity of the multifunctional polymer electrolyte membrane obtained in Example 2 at room temperature (25°C) is 2.0×10 -3 S / cm, and the ionic conductivity at 50°C is 3.4×10 -3 S / cm; the tensile strength of the multifunctional polymer electrolyte membrane obtained in Example 2 is 55MPa, the elongation at break is 28%, and the anti-fatigue performance is: after 100 bending cycles, the tensile strength retention rate is 91%, and the elongation at break retention rate is 87%; the self-healing performance of the multifunctional polymer electrolyte membrane obtained in Example 2 is: after 25min, the self-healing efficiency reaches 90%; the membrane size change of the multifunctional polymer electrolyte membrane obtained in Example 2 is less than 2% within the temperature change range of 25 to 85°C; the initial capacity of the battery prepared by the multifunctional polymer electrolyte membrane obtained in Example 2 is 158mAh / g, and the capacity retention rate is 95% after 100 cycles; the discharge specific capacities at different rates (0.1C, 0.5C, 1C, 3C) are 158mAh / g, 152mAh / g, 145mAh / g, and 132mAh / g, respectively.

[0116] Example 3

[0117] This embodiment provides a method for preparing a multifunctional polymer electrolyte membrane, comprising the following steps:

[0118] The substrate material is polyvinylidene fluoride (PVDF, weight average molecular weight 5.3×10 5 g / mol, Arkema, brand Kynar 761) and polymethyl methacrylate (PMMA, weight average molecular weight 8×10 4 g / mol) was dissolved in trifluoroethanol (TFE) solvent at a mass ratio of 3:2 and stirred evenly to obtain a basic solution;

[0119] Polyurethane (PU, weight average molecular weight 7×10 4 g / mol) as self-healing material, a mixture of lithium salt LiTFSI and ionic liquid [EMIM][TFSI] (lithium salt and ionic liquid mass ratio 1:1) as conductive material, nano silicon dioxide (SiO 2 , manufacturer AlfaAesar, brand A3785) as a reinforcing material, the concentration of the base material is 20wt%, the concentration of the self-healing material is 4wt%, the concentration of the conductive material is 10wt%, the concentration of the reinforcing material is 1wt%, and the mixture is evenly mixed, and an ultrasonic treatment device (power 180W, frequency 40kHz) is used for ultrasonic treatment for 20min to ensure that all components are completely dispersed to obtain a composite solution;

[0120] The composite solution was electrospun, and the electrospinning parameters were set as follows: voltage 18 kV, working distance 16 cm, injection rate 0.7 mL / h, temperature 25°C, humidity 40%, to obtain a spinning membrane; the spinning membrane was heat treated at 110°C for 2 h to obtain a nanofiber membrane with a porosity of 40% and a pore size distribution of 200 to 300 nm;

[0121] Chitosan (Sigma-Aldrich, brand C3646), lithium carbonate (Li 2 CO 3 , particle size 5 μm) and a thermal response material solution of a deionized water-ethanol mixed solvent (deionized water: ethanol = 1: 1 v / v), chitosan concentration 6wt%, Li 2 CO 3 The concentration is 12wt%;

[0122] The thermal response material solution was coated on the surface of the nanofiber membrane by a casting coating method. The coating amount of the thermal response material was 0.9 mg / cm 2 ; The coated membrane was dried at 55°C for 30 minutes to obtain a multifunctional polymer electrolyte membrane.

[0123] Test Example 3

[0124] The performance of the multifunctional polymer electrolyte membrane obtained in Example 3 was tested by the test method of Test Example 1. It can be found that the ionic conductivity of the multifunctional polymer electrolyte membrane obtained in Example 3 at room temperature (25°C) is 2.2×10 -3 S / cm, and the ionic conductivity at 50°C is 3.6×10 -3 S / cm; the tensile strength of the multifunctional polymer electrolyte membrane obtained in Example 3 is 58MPa, the elongation at break is 27%, and the fatigue resistance is: after 100 bending cycles, the tensile strength retention rate is 92%, and the elongation at break retention rate is 88%; the self-healing performance of the multifunctional polymer electrolyte membrane obtained in Example 3 is: after 20min, the self-healing efficiency reaches 93%; the membrane size change of the multifunctional polymer electrolyte membrane obtained in Example 3 is less than 3% within the temperature range of 20 to 80°C; the initial capacity of the battery prepared with the multifunctional polymer electrolyte membrane obtained in Example 3 is 162mAh / g, and the capacity retention rate is 96% after 100 cycles; the discharge specific capacities at different rates (0.1C, 0.5C, 1C, 3C) are 162mAh / g, 158mAh / g, 150mAh / g, and 137mAh / g, respectively.

[0125] Example 4

[0126] This embodiment provides a method for preparing a multifunctional polymer electrolyte membrane, comprising the following steps:

[0127] The base material is polyetheretherketone (PEEK, weight average molecular weight 1.3×10 5 g / mol) and polylactic acid (PLA, weight average molecular weight 9×10 4 g / mol) was dissolved in butyl acetate (EBA) solvent at a mass ratio of 4:1 and stirred evenly to obtain a basic solution;

[0128] Poly(lactic acid-co-glycolic acid) copolymer (PLGA, copolymerization ratio 70:30) as self-healing material, lithium salt LiPF 6 A mixture of ionic liquid [BMIM][TFSI] (lithium salt to ionic liquid mass ratio 3:2) was used as a conductive material, and carbon nanotubes (CNTs, manufacturer NanoAmor, brand CNT99) were used as a reinforcing material. The concentration of the base material was 12wt%, the concentration of the self-healing material was 5wt%, the concentration of the conductive material was 8wt%, and the concentration of the reinforcing material was 5wt%. The mixture was mixed evenly, and an ultrasonic treatment device (power 200W, frequency 40kHz) was used for ultrasonic treatment for 25min to ensure that all components were completely dispersed to obtain a composite solution.

[0129] The composite solution was electrospun, and the electrospinning parameters were set as follows: voltage 15 kV, working distance 12 cm, injection rate 0.6 mL / h, temperature 25° C., humidity 40%, to obtain a spinning membrane; the spinning membrane was heat treated at 100° C. for 2 h to obtain a nanofiber membrane with a porosity of 50% and a pore size distribution of 150 to 300 nm;

[0130] Preparation of polyvinyl alcohol (PVA, weight average molecular weight 8×10 4 g / mol), lithium carbonate (Li 2 CO 3 , particle size 5 μm) and a deionized water-trifluoroethanol mixed solvent (deionized water: trifluoroethanol = 1: 1 v / v) thermal response material solution, PVA concentration 8wt%, Li 2 CO 3 The concentration is 10wt%;

[0131] The thermal response material solution was coated on the surface of the nanofiber membrane by a casting coating method. The coating amount of the thermal response material was 0.8 mg / cm 2 ; The coated membrane was dried at 60°C for 40 minutes to obtain a multifunctional polymer electrolyte membrane.

[0132] Test Example 4

[0133] The performance of the multifunctional polymer electrolyte membrane obtained in Example 4 was tested by the test method of Test Example 1. It can be seen that the ionic conductivity of the multifunctional polymer electrolyte membrane obtained in Example 4 at room temperature (25°C) is 1.8×10 -3 S / cm, and the ionic conductivity at 50°C is 3.2×10 -3 S / cm; the tensile strength of the multifunctional polymer electrolyte membrane obtained in Example 4 is 65MPa, the elongation at break is 32%, and the fatigue resistance is: after 100 bending cycles, the tensile strength retention rate is 95%, and the elongation at break retention rate is 90%; the self-healing performance of the multifunctional polymer electrolyte membrane obtained in Example 4 is: after 15min, the self-healing efficiency reaches 95%; the membrane size change of the multifunctional polymer electrolyte membrane obtained in Example 4 is less than 2% within the temperature range of 25 to 85°C; the initial capacity of the battery prepared with the multifunctional polymer electrolyte membrane obtained in Example 4 is 150mAh / g, and the capacity retention rate is 94% after 100 cycles; the discharge specific capacities at different rates (0.1C, 0.5C, 1C, 3C) are 150mAh / g, 145mAh / g, 140mAh / g, and 130mAh / g, respectively.

[0134] Application Example 1

[0135] The multifunctional polymer electrolyte membrane obtained in Example 4 is applied to a flexible lithium-ion battery. The battery structure of the flexible lithium-ion battery includes:

[0136] Positive electrode layer: Material: LiFePO 4 (particle size 5 μm), conductive carbon black (Super P) and PVDF binder, ratio = 80:10:10 (mass ratio); preparation: the above materials are mixed in proportion, an appropriate amount of N-methylpyrrolidone (NMP) is added as a solvent, and stirred evenly to prepare a positive electrode slurry; the positive electrode slurry is coated on a flexible aluminum foil by a casting method, with a thickness of 50 μm; the coated positive electrode layer is dried at 80°C for 12 hours to obtain a positive electrode sheet;

[0137] Negative electrode layer: Material: Metal lithium film (thickness 50 μm); Preparation: The metal lithium film is directly attached to the flexible copper foil through a pressing process to prepare a negative electrode sheet;

[0138] Electrolyte membrane: The multifunctional polymer electrolyte membrane prepared in Example 4 was used as a separator and an electrolyte;

[0139] Packaging structure: Outer layer material: flexible polyimide (PI) film; Sealing method: Using hot pressing packaging process, the positive electrode, electrolyte membrane and negative electrode are stacked and then sealed into a flexible battery cell through a vacuum packaging machine.

[0140] Performance Test:

[0141] Multiple charge and discharge tests: At a rate of 0.5C, the battery is cycled for 100 times at 25-60°C to test the battery's capacity retention rate and voltage platform;

[0142] Bending and stretching condition test: 100 cycles of testing were performed at a bending radius of 10 mm to measure the capacity retention rate, voltage change and internal resistance change of the battery after bending; the stretching rate was 10%, and 100 stretching cycles were performed to measure the mechanical integrity and electrochemical performance of the battery after stretching;

[0143] The test results of Application Example 1 show that the capacity retention rate of the obtained flexible lithium-ion battery is 95%, showing excellent stability, and the voltage platform is 3.4V; the capacity retention rate after bending is 94%, the voltage change is ±0.05V, and the internal resistance change is less than 3%; there is no obvious voltage drift after stretching, the internal resistance increase is less than 5%, and the battery maintains good mechanical integrity and electrochemical stability.

[0144] Application Example 2

[0145] The multifunctional polymer electrolyte membrane obtained in Example 3 is applied to a battery system of a wearable device, and the battery system structure thereof includes:

[0146] Positive electrode layer: Material: LiCoO 2 (particle size 3μm), conductive carbon black (SuperP), PVDF binder, ratio = 85:10:5 (mass ratio); preparation: the above materials are mixed in proportion, an appropriate amount of N-methylpyrrolidone (NMP) is added as a solvent, and stirred evenly to prepare a positive electrode slurry; the positive electrode slurry is evenly coated on a flexible aluminum foil using a casting method, and the coating thickness is 40μm; the coated positive electrode layer is dried at 80°C for 10h to obtain a positive electrode sheet;

[0147] Negative electrode layer: Material: flexible graphite negative electrode (thickness 20 μm); Preparation: Use flexible graphite sheet and directly attach it to flexible copper foil through a pressing process to form a negative electrode sheet;

[0148] Electrolyte membrane: the multifunctional polymer electrolyte membrane prepared in Example 3 was used;

[0149] Packaging structure: Outer layer material: medical grade flexible polyimide (PI) film; System design: Combined with flexible conductive circuits, and the battery system is sealed using a hot pressing packaging process, suitable for wearable devices.

[0150] Performance Test:

[0151] Continuous wearing test: The prepared battery system is fixed on a flexible wearable device and worn continuously for 72 hours to simulate human activities (including bending, stretching, and local compression) to test the battery's capacity retention and mechanical integrity during long-term wearing.

[0152] Environmental adaptability test: Carry out charge and discharge tests at -20℃, 0℃, 25℃, and 60℃ respectively to measure the battery capacity retention rate and charge and discharge efficiency at different temperatures;

[0153] Pressure change test: Use a pressure test device to simulate the local pressure (0.1-0.5MPa) when worn by the human body, and record the dimensional changes of the membrane and the electrochemical performance of the battery under different pressure conditions.

[0154] The test results of Application Example 2 show that the obtained multifunctional polymer electrolyte membrane has no damage during 72 hours of wearing, the mechanical integrity of the membrane is good, and the battery capacity retention rate is 93%; the capacity retention rate is 85% at -20°C, 90% at 0°C, 98% at 25°C, and 95% at 60°C, showing good temperature adaptability; within the pressure range of 0.1 to 0.5 MPa, the size of the membrane changes by less than 2%, the battery has no performance degradation, and exhibits excellent mechanical stability and electrochemical stability.

[0155] In summary, the above application examples prove that the multifunctional polymer electrolyte membrane prepared by the present invention is not only suitable for lithium-ion batteries, but also has broad application prospects. It can meet the needs of new battery systems such as flexible electronic devices, wearable devices, and flexible energy storage devices, and help promote the further development of flexible electronic technology.

[0156] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a multifunctional polymer electrolyte membrane, characterized in that: The following steps are involved: The base material, the self-healing material, the conductive material, the reinforcing material and the solvent are mixed to obtain a composite solution; the composite solution is subjected to electrostatic spinning, and the membrane material obtained by electrostatic spinning is subjected to heat treatment to obtain a nanofiber membrane; The solution of the thermal response material is coated on the nanofiber membrane and dried to obtain a multifunctional polymer electrolyte membrane; Wherein, the substrate material includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyetheretherketone, polylactic acid, polyethersulfone, and polymethyl methacrylate; The self-healing material includes one or more of polydisulfide, polyurea, polyurethane, polyethylene glycol diacrylate, polyacrylic acid, polymethacrylate, and polylactic acid-glycolic acid copolymer; The conductive material includes a blend of a lithium salt and an ionic liquid; The reinforcing material includes one or more of graphene, carbon nanotubes, graphene oxide, carbon black, nano silicon fiber, and nano silicon dioxide; The thermal response material includes a blend of a polymer material and an inorganic lithium salt.

2. The preparation method according to claim 1, characterized in that: In the conductive material, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide; the ionic liquid includes one or more of imidazole ionic liquid, pyridine ionic liquid, and phosphate ionic liquid; In the conductive material, the mass ratio of the lithium salt to the ionic liquid is 2:1 to 1:

2.

3. The preparation method according to claim 2, characterized in that: The imidazolium ionic liquid includes one or more of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; The pyridinium ionic liquid includes one or more of 1-butylpyridinium tetrafluoroborate, 1-ethylpyridinium hexafluorophosphate, 1-propylpyridinium bis(trifluoromethylsulfonyl)imide, 1-butylpyridinium hexafluorophosphate, 1-methylpyridinium tetrafluoroborate, 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide, 1-octylpyridinium hexafluorophosphate, 1-propylpyridinium tetrafluoroborate, 1-phenylpyridinium bis(trifluoromethylsulfonyl)imide, and 1-methylpyridinium hexafluorophosphate; The phosphate ionic liquid includes one or more of 1-butyl-3-methylimidazolium trimethyl (trifluoromethylsulfonyl) phosphate, 1-ethyl-3-methylimidazolium trimethyl phosphate, and 1-butyl-3-methylimidazolium triethyl phosphate.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In the composite solution, the mass concentration of the base material is 12-20%, the mass concentration of the self-healing material is 2-5%, the mass concentration of the conductive material is 8-15%, and the mass concentration of the reinforcing material is 1-5%.

5. The preparation method according to claim 4, characterized in that: The electrostatic spinning conditions include: voltage of 15-20 kV, working distance of 12-20 cm, injection rate of 0.3-1 mL / h, temperature of 20-30° C., and humidity of 30-50%.

6. The preparation method according to claim 1 or 5, characterized in that: The heat treatment conditions include: temperature of 80-120° C. and time of 0.5-2 h.

7. The preparation method according to claim 1, characterized in that: In the thermal response material, the polymer material includes one or more of polyvinyl alcohol, hydroxypropyl methylcellulose, and chitosan, and the inorganic lithium salt includes one or more of lithium carbonate, lithium chloride, lithium hydroxide, lithium nitrate, lithium sulfate, lithium dihydrogen phosphate, and lithium bicarbonate; In the thermal response material, the mass ratio of the polymer material to the inorganic lithium salt is 4:1 to 0.5:

1.

8. The preparation method according to claim 1 or 7, characterized in that: The drying conditions include: a temperature of 50 to 80°C and a time of 0.5 to 1 hour; The coating amount of the thermal response material on the nanofiber membrane is 0.5-1 mg / cm 2 .

9. A multifunctional polymer electrolyte membrane obtained according to the preparation method according to any one of claims 1 to 8.

10. Use of the multifunctional polymer electrolyte membrane according to claim 9 in flexible electronic devices.