In-situ gelled double cross-linked polymer electrolyte, preparation method thereof and application thereof

Abstract

The present invention discloses an in-situ gelled double cross-linked polymer electrolyte, a preparation method and an application thereof. A polymer nanofiber membrane is prepared by an electrostatic spinning method, a cross-linked nanofiber membrane is obtained by heat treatment, and then a mixed solution of an organic electrolyte and a cross-linking agent is impregnated to obtain a double cross-linked polymer solid electrolyte membrane material through in-situ cross-linking gelation. The double cross-linked polymer solid electrolyte membrane material has high porosity, high liquid absorption rate, excellent mechanical strength and thermal stability, and good electrochemical properties. It has high ionic conductivity and lithium ion transfer number, high oxidative decomposition potential, and has excellent rate performance and cycle performance when used in lithium-ion batteries, thus solving the problems of low ionic conductivity and poor mechanical properties of polymer electrolytes.

Description

Technical field:

[0001] The invention relates to an in-situ gelled double cross-linked polymer electrolyte, a preparation method and application thereof. Background technology:

[0002] Lithium-ion batteries are widely used in portable electronic devices such as mobile phones and laptops due to their high operating voltage, high energy density, lack of memory effect, and long cycle life. With the rapid development of electric vehicles and energy storage grid systems, people have increasingly stringent requirements for the performance and safety of lithium-ion batteries. As an essential component of lithium-ion batteries, electrolytes transport ions and conduct current between the positive and negative electrodes of the battery, which has a profound impact on the performance and safety of lithium-ion batteries. Currently, commercial lithium batteries mostly use liquid electrolytes containing carbonate organic solvents, which pose safety risks such as leakage and flammability, hindering their further application. Compared with organic electrolytes, the use of polymer electrolytes can avoid the leakage problems of traditional lithium batteries, improve battery safety, have better compatibility with electrodes, and inhibit the growth of lithium dendrites. At the same time, their excellent mechanical processing properties make thin-film, miniaturized, flexible, and bendable lithium batteries possible.

[0003] Polymer electrolytes have low room-temperature ionic conductivity, typically requiring elevated temperatures to meet practical application requirements. Polymers are typically modified through the incorporation of inorganic fillers, blending, copolymerization, and crosslinking to improve their ionic conductivity and mechanical strength. Patent CN110071328B discloses a crosslinked polyethyleneimine polymer electrolyte. This polymer electrolyte is crosslinked via a Michael addition reaction between a crosslinker and polyethyleneimine, and then directly coated with a lithium salt to form a film. The resulting polymer electrolyte exhibits enhanced thermal stability, ionic conductivity, and electrochemical window, but its room-temperature ionic conductivity requires further optimization and improvement. Summary of the invention:

[0004] The purpose of the present invention is to provide an in-situ gelled double cross-linked polymer electrolyte, a preparation method and application thereof, wherein a polymer nanofiber membrane is prepared by an electrospinning method, a cross-linked nanofiber membrane is obtained by heat treatment, and then a mixed solution of an organic electrolyte and a cross-linking agent is impregnated to obtain a double cross-linked polymer solid electrolyte membrane material through in-situ cross-linking gelation. The double cross-linked polymer solid electrolyte membrane material has high porosity, high liquid absorption rate, excellent mechanical strength and thermal stability, and good electrochemical properties, high ionic conductivity and lithium ion transfer number, high oxidative decomposition potential, and has excellent rate performance and cycle performance when used in lithium-ion batteries, thereby solving the problems of low ionic conductivity and poor mechanical properties of polymer electrolytes.

[0005] The present invention is achieved through the following technical solutions:

[0006] An in-situ gelled double-crosslinked polymer electrolyte is prepared by dissolving a functional polymer containing nitrile or ester groups and an amino-containing polymer in N,N-dimethylformamide to form a spinning solution. A nanofiber membrane is prepared by an electrospinning process, which is flattened and then heat-treated at 100-170°C for cross-linking. A mixed solution of a crosslinking agent and an organic electrolyte is added to obtain an in-situ gelled double-crosslinked polymer electrolyte.

[0007] Particularly, a lithium salt is added to the spinning solution, and the lithium salt is selected from one or more of LiN(SO2CF3)2, LiCF3SO3, and LiN(SO2CF2CF3)2.

[0008] The functional polymer containing nitrile groups is selected from polyacrylonitrile or its copolymer with a number average molecular weight of 85,000 to 150,000.

[0009] The functional polymer containing ester group is selected from one or more of polyhydroxyethyl acrylate, polybutyl acrylate and polymethyl acrylate.

[0010] The amine-containing polymer is one or more of branched polyethyleneimine, linear polyethyleneimine, polypropyleneimine, and polyacrylamide, and is preferably branched polyethyleneimine with a number average molecular weight of 20,000 to 100,000.

[0011] Preferably, the mass ratio of the cyano or ester group-containing polymer to the amine group-containing polymer is 1 to 9:1.

[0012] Preferably, the key parameters of electrospinning are: spinning solution concentration of 5-15wt%, spinning electrostatic voltage of 15-25kV, receiving distance of 10-20cm, and injection speed of 0.4-1ml / h.

[0013] The crosslinking agent is selected from one or more of 2-hydroxyethyl acrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate.

[0014] Preferably, in the mixed solution of the cross-linking agent and the organic electrolyte, the mass fraction of the cross-linking agent is 0.01% to 20%.

[0015] The organic electrolyte includes a lithium salt and an organic solvent. The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate; and the organic solvent is selected from one or more of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), vinyl ethylene carbonate (VEC), vinylene carbonate (VC), propyl acetate (PA), and fluoroethylene carbonate (FEC). The molar concentration of the lithium salt in the organic electrolyte is 0.5-2 mol / L, preferably 1 mol / L.

[0016] Preferably, the organic electrolyte is 1 mol of LiPF6 dissolved in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1.

[0017] The invention also protects the application of in-situ gelled double cross-linked polymer electrolyte, which is applied to electrochemical energy storage devices or solar cells.

[0018] The electrochemical energy storage devices include lithium-ion batteries, lithium-air batteries, lithium-sulfur batteries, fuel cells, supercapacitors and other metal electrochemical batteries, such as sodium batteries and zinc batteries.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1) Compared with polymer electrolyte membranes prepared by other processes, the polymer nanofiber membrane obtained by the electrospinning method of the present invention has a higher porosity and high specific surface area, which is conducive to the adsorption of electrolyte and improves ionic conductivity. The highest porosity is 81.3% and the liquid absorption rate is 575%, providing a basis for high ionic conductivity.

[0021] 2) The double-crosslinked nanofiber membrane obtained in the present invention has excellent mechanical properties, wherein the highest tensile strength is 9.36 MPa and the highest elongation at break is 60%, and it can be folded and wrinkled at will without obvious visible damage.

[0022] 3) Compared with traditional liquid electrolytes, the cross-linked polymer electrolyte of the present invention has higher safety and thermal stability, can remain stable without decomposition within 300°C, and has less thermal shrinkage than commercial separators.

[0023] 4) Compared with traditional liquid electrolytes, the dual-crosslinked polymer electrolyte of the present invention has a higher oxidation potential of 5.7V (vs. Li / Li+), which is a significant improvement over traditional liquid electrolytes. It can meet the battery design requirements of more high-voltage positive electrode materials, thereby providing a basis for further improving the energy density of lithium-ion batteries.

[0024] 5) The double-crosslinked polymer electrolyte proposed in the present invention has an ion transfer number of 0.73, which is significantly improved compared with traditional liquid electrolytes. It effectively reduces the concentration polarization of anions during charge and discharge, which is beneficial to prolonging the service life of lithium-ion batteries.

[0025] 6) Compared with traditional liquid electrolytes, the dual-crosslinked polymer electrolyte proposed in the present invention has better stability with the lithium metal interface and can be stably electroplated / stripped on the lithium surface for more than 1200 hours without short circuiting.

[0026] 7) When the double-crosslinked polymer electrolyte proposed in the present invention is applied to the high-energy-density ternary high-nickel cathode material (NCM811), the assembled Li / NCM811 half-cell has excellent rate performance and cycle performance.

[0027] 8) When the dual-crosslinked polymer electrolyte proposed in the present invention is applied to the high-energy-density ternary high-nickel cathode material (NCM811), the assembled NCM811 / graphite full battery has excellent long-cycle performance.

[0028] In summary, the double-crosslinked polymer electrolyte obtained by the present invention has high porosity, high liquid absorption rate, excellent mechanical strength and thermal stability, and good electrochemical performance. It has high ionic conductivity and lithium ion transfer number, high oxidative decomposition potential, better interface stability with lithium metal, and has excellent rate performance and cycle performance when used in lithium-ion batteries, solving the problems of low ionic conductivity and poor mechanical properties of polymer electrolytes. Description of the drawings:

[0029] Figure 1 Schematic diagram of polymer electrolyte preparation.

[0030] Figure 2 This is the morphology of the nanofiber membrane described in Example 1 under an electron scanning microscope.

[0031] Figure 3 This is the morphology of the lithium salt-containing nanofiber membrane described in Example 6 under an electron scanning microscope.

[0032] Figure 4 This is the thermogravimetric analysis curve of the nanofiber membrane described in Example 1.

[0033] Figure 5 This is the differential thermal scanning test curve of the nanofiber membrane described in Example 1.

[0034] Figure 6 This is a dimensional stability test of the nanofiber membrane described in Example 1 and a commercial separator.

[0035] Figure 7 These are stress-strain curve test curves of the nanofiber membranes obtained from Examples 1-5 with different ratios of polyacrylonitrile and polyethyleneimine.

[0036] Figure 8 This is a bending and folding test of the nanofiber membrane of Example 1.

[0037] Figure 9 These are the liquid retention and ionic conductivity of the polymer electrolytes of Examples 1 and 7 to 10.

[0038] Figure 101 is a fitting curve of the relationship between ionic conductivity and temperature of the polymer electrolyte of Example 1.

[0039] Figure 11 1 is a curve showing the polarization response current of the polymer electrolyte of Example 1 changing with time (the inner figure is the impedance spectrum of the lithium symmetric battery before and after polarization).

[0040] Figure 12 This is a linear sweep voltammetry comparison curve of the polymer electrolyte and the organic electrolyte in Example 1.

[0041] Figure 13 This is a comparison curve of lithium plating / stripping tests of the polymer electrolyte and the organic electrolyte in Example 1.

[0042] Figure 14 This is the rate performance of the polymer electrolyte of Example 1.

[0043] Figure 15 This is a half-cell long cycle test of the polymer electrolyte and the organic electrolyte in Example 1.

[0044] Figure 16 This is a full battery long cycle test of the polymer electrolyte and organic electrolyte in Example 1.

[0045] Figure 17 This is the differential thermal scanning test curve of the cross-linking of polyacrylamide and polyethyleneimine in Example 11.

[0046] Figure 18 This is the differential thermal scanning test curve of the cross-linking of polybutyl acrylate and polyethyleneimine in Example 12. Specific implementation method:

[0047] The following is a further description of the present invention, but not a limitation of the present invention.

[0048] Example 1:

[0049] Step (1), preparation of polyethyleneimine and polyacrylonitrile cross-linked nanofiber membrane: 0.2g polyethyleneimine and 0.8g polyacrylonitrile were weighed using an electronic balance and dissolved in 9g N,N-dimethylformamide to prepare a 10wt% spinning solution. The solution was stirred evenly at 60°C to obtain a homogeneous clear spinning solution. The polyacrylonitrile and polyethyleneimine nanofiber membrane was prepared by electrospinning under the following conditions: voltage of 18kV, injection speed of 0.6ml / h, needle diameter of 0.21-2.1mm, receiving distance of 20cm, aluminum foil receiving, and spinning time of 8 hours. After the electrospinning is completed, the recovered nanofiber membrane is peeled off from the aluminum foil, rolled flat on a roller, and then placed under heat treatment at 120°C. The nitrile group of the polyacrylonitrile and the amine group of the polyethyleneimine are thermally cross-linked to obtain a cross-linked polyethyleneimine and polyacrylonitrile nanofiber membrane.

[0050] Step (2), preparing a double cross-linked polymer electrolyte: The nanofiber membrane obtained in step (1) is punched into 16mm discs using a laminator, dried in a vacuum oven, and then transferred to a glove box filled with an argon atmosphere, wherein the ppm of H2O and O2 are both less than 0.1. A mixed solution of a cross-linking agent tripropylene glycol diacrylate and an organic electrolyte is prepared, wherein the mass fraction of the cross-linking agent in the mixed solution is 10wt%. The organic electrolyte is obtained by dissolving 1 mol of LiPF6 in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1. The mixed solution containing the cross-linking agent and the organic electrolyte is dripped into the nanofiber membrane and allowed to stand for adsorption. The cross-linking agent is gelled in situ to seal the electrolyte in the nanofiber membrane to prepare a double cross-linked polymer electrolyte.

[0051] Step (3): assembling the double cross-linked polymer electrolyte obtained in step (2) into a polymer half-cell with a ternary high-nickel positive electrode material and lithium metal as the negative electrode to perform rate performance and cycle performance tests.

[0052] Step (4): assemble the double cross-linked polymer electrolyte obtained in step (2) into a polymer full battery with a ternary high-nickel positive electrode material and graphite as the negative electrode for long cycle performance testing.

[0053] The cross-linked nanofiber membrane obtained in step (1) of Example 1 was subjected to a morphology test experiment: the test instrument was a scanning electron microscope (SEM), and the test instrument was a Hitachi model S-4800 from Japan. The results showed that the nanofiber membrane was composed of a stack of polymer fiber membranes with an average diameter of 580 nm. Figure 2 .

[0054] The porosity and liquid absorption rate of the cross-linked nanofiber membrane obtained in step (1) of Example 1 were tested: the adsorbent used was n-butanol, and the membrane was cut into 16 mm discs by a punching machine and weighed to record the original dry membrane weight m o , soak the membrane in n-butanol solution for 1 hour and then weigh and record the wet membrane weight m t . Through the formula P=m t -m o / ρV to calculate the porosity, where ρ is the density of n-butanol and V is the volume of the disc. The reagent used in the liquid absorption test is electrolyte. The membrane is cut into 16mm discs by a punching machine and weighed to record the original dry film weight m o , soak the membrane in the electrolyte for 1 hour and then weigh and record the wet membrane weight m t . Through the formula P=m t -m o / m o Calculate the liquid absorption rate and refer to Table 1 for the test results.

[0055] Table 1

[0056] Porosity / % Liquid absorption rate / % <![CDATA[Room temperature ionic conductivity / mS cm -1 > Example 1 81.3 575 3.39 Example 2 77.2 545 2.63 Example 3 77.6 568 2.97 Example 4 74.2 497 2.45 Example 5 74.0 527 1.97 Example 6 74.3 501 3.61

[0057] The cross-linked nanofiber membrane obtained in step (1) of Example 1 was subjected to a thermal stability test: the test method was thermal gravimetric analysis (TGA), the test instrument was a model Zennium / IM6 from Zahner, Germany, the test atmosphere was argon, and the test conditions were 0-700°C (10°C / min). The results showed that the prepared cross-linked nanofiber membrane had excellent thermal stability and remained stable without decomposition within 300°C. The thermal stability test curve was referenced to Figure 4 .

[0058] The cross-linked nanofiber membrane obtained in step (1) of Example 1 was subjected to a cross-linking test experiment: the test method was differential scanning calorimetry (DSC), the test instrument was STA 409 PC model from Netzsch Company, Germany, the test atmosphere was argon, and the test conditions were 0-200°C (10°C / min). The results showed that the cross-linking temperature of polyacrylonitrile and polyethyleneimine was 120°C, and the glass transition temperature of the cross-linked nanofiber membrane was 92°C. The test curve was referenced to Figure 5 .

[0059] The cross-linked nanofiber membrane obtained in step (1) of Example 1 was subjected to a heat shrinkage test: the nanofiber membrane was heated at 100°C, 120°C, 140°C, and 160°C for one hour each to observe its morphological changes and compare it with a commercial separator (Celgard 2325). The results showed that the shrinkage of the prepared cross-linked nanofiber membrane at high temperature was negligible, while the commercial separator showed obvious shrinkage. The test image is referenced. Figure 6 .

[0060] The mechanical properties of the cross-linked nanofiber membrane obtained in step (1) of Example 1 were tested: the nanofiber membrane was cut into dumbbell shapes, and the test instrument was an electronic tensile machine. The dumbbell-shaped sample was stretched at a constant speed of 10 mm / min until the sample broke. The results showed that the nanofiber membrane with the best performance had a tensile strength of 9.36 MPa and an elongation at break of 24%. The test curve was referenced to Figure 7 The prepared nanofiber membrane was randomly folded and curled without obvious damage. The result image is referenced Figure 8 .

[0061] The double cross-linked polymer electrolyte film obtained in step (2) of Example 1 was tested for ionic conductivity: the polymer electrolyte was assembled into stainless steel / electrolyte / stainless steel blocking electrodes, which were then encapsulated in a CR2025 button battery. The ionic conductivity of the electrolyte was tested using the AC impedance method of a CHI604C electrochemical workstation, and the battery temperature was controlled using a high and low temperature oven. The results showed that the liquid retention rate of the polymer electrolyte was positively correlated with the mass fraction of the cross-linking agent, but when too much cross-linking agent was added, the ionic conductivity of the electrolyte was affected. The optimal ionic conductivity at room temperature was 3.39 mS / cm. The test results refer to Figure 9 ; And the ionic conductivity at different temperatures was measured and converted to fit the Arrhenius equation. According to the fitting parameters, the activation energy was calculated to be 9.05kJ / mol. The test result curve is referenced Figure 10 .

[0062] The double cross-linked polymer electrolyte film obtained in step (2) of Example 1 was tested for lithium ion migration number: the polymer electrolyte was assembled into a lithium sheet / electrolyte / lithium sheet blocking electrode, and then encapsulated in a CR2025 button battery. The lithium ion migration number of the electrolyte was tested using the chronoamperometry method of a CHI604C electrochemical workstation. The test results showed that the lithium ion migration number of the polymer electrolyte was 0.73, which is higher than that of the organic electrolyte system. The test curve is referenced. Figure 11 .

[0063] The electrochemical stability test of the double cross-linked polymer electrolyte film obtained in step (2) of Example 1 was conducted: the polymer electrolyte was assembled into a lithium sheet / electrolyte / steel sheet, and then encapsulated in a CR2025 button battery. The electrochemical stability window of the electrolyte was tested using the linear voltammetry method of a CHI604C electrochemical workstation. The results showed that the oxidation potential of the polymer electrolyte was 5.7V and the reduction potential was 0.3V, so the electrochemical stability window was 5.4V, which was higher than that of the organic electrolyte system. The test curve was referenced. Figure 12 .

[0064] The double-crosslinked polymer electrolyte film obtained in step (2) of Example 1 was subjected to a lithium metal plating / stripping performance test: the polymer electrolyte was assembled to form a lithium sheet / electrolyte / lithium sheet blocking electrode, which was then encapsulated in a CR2025 button battery, and its interface stability with lithium metal was tested by constant current charge and discharge. The results show that the overpotential of the lithium symmetric battery using an organic electrolyte increases significantly with increasing cycle time, and then suddenly decreases at around 700 hours, indicating that the battery failure is caused by a short circuit caused by the accumulation of lithium dendrite growth. In contrast, the polymer electrolyte exhibits excellent cycle stability, with no obvious oscillations in more than 1200 hours of stable cycling at low voltage. Compared with organic electrolytes, the surface polymer electrolyte has highly stable lithium plating / stripping reversibility and the ability to inhibit lithium dendrite growth. The test curve refers to Figure 13 .

[0065] The double cross-linked polymer electrolyte film obtained in step (2) of Example 1 was subjected to a half-cell test: the polymer electrolyte was assembled into a LiNi 0.8 Co 0.1 Mn 0.1 / electrolyte / lithium sheet half-cell, and its rate performance and cycle performance were tested by constant current charge and discharge. The discharge capacity of the battery at 0.1C, 0.2C, 0.5C, 1C and 2C were 203, 196, 182, 171 and 163 mAh / g, respectively. The specific reversible capacity decreases with the increase of the current value from 0.1C to 2C. It is worth mentioning that after 5 cycles of 2C test, when it returns to 0.2C cycle, it can almost completely recover to the high capacity of 196 mAh / g at the previous 0.2C cycle, indicating that even when matched with a nickel-rich NCM811 cathode with a high specific capacity, the electrolyte also shows excellent electrochemical cycle reversibility. The test curve refers to Figure 14 ; In a long cycle test at a current density of 0.5C, the polymer electrolyte battery showed a higher initial coulombic efficiency of 82%, while the organic electrolyte was 76%. The initial discharge capacity of the polymer electrolyte was 189.2mAh / g, slightly higher than the 157.2mAh / g of the organic electrolyte. After 400 cycles, the discharge capacity of the polymer electrolyte remained at 103.0mAh / g, with a capacity retention rate of 56.5%. The test curve is referenced Figure 15 .

[0066] The double cross-linked polymer electrolyte film obtained in step (2) of Example 1 was subjected to full battery testing: the polymer electrolyte was assembled to form a LiNi0.8Co0.1Mn0.1 / electrolyte / graphite full battery, and its cycle performance was tested by constant current charge and discharge. The test curve is referenced to Figure 16The battery equipped with the polymer electrolyte had an initial discharge capacity of 175 mAh / g after 200 cycles at a current density of 0.5 C, with a capacity retention rate of 91.4%.

[0067] Example 2:

[0068] Refer to Example 1, except that in step (1), the amount of polyacrylonitrile in the nanofiber membrane preparation is 0.9 g and the amount of polyethyleneimine is 0.1 g, i.e., the mass ratio is 9:1. Step (2) is the same as in Example 1.

[0069] Example 3:

[0070] Refer to Example 1, except that in step (1), the amount of polyacrylonitrile in the nanofiber membrane preparation is 0.7 g and the amount of polyethyleneimine is 0.3 g, i.e., the mass ratio is 7:3. Step (2) is the same as in Example 1.

[0071] Example 4:

[0072] Refer to Example 1, except that in step (1), the nanofiber membrane is prepared with 0.6 g of polyacrylonitrile and 0.4 g of polyethyleneimine, i.e., a mass ratio of 6:4. Step (2) is the same as in Example 1.

[0073] Example 5:

[0074] Refer to Example 1, except that in step (1), the nanofiber membrane is prepared with 0.5 g of polyacrylonitrile and 0.5 g of polyethyleneimine, i.e., the mass ratio is 5:5. Step (2) is the same as in Example 1.

[0075] Example 6:

[0076] Refer to Example 1, except that in step (1), 0.8 g of polyacrylonitrile and 0.2 g of polyethyleneimine are used in the preparation of nanofiber membrane, and 0.1 g of lithium salt LiTFSI is added. The cross-linked polymer nanofiber membrane containing lithium salt is prepared, and the morphology is shown in the scanning electron microscope image. Figure 3 The addition of lithium salt is beneficial to improving ionic conductivity. Please refer to Table 1 for specific conductivity test results.

[0077] Example 7:

[0078] Referring to Example 1, step (1) is the same as Example 1, except for step (2). The main difference is that the mass fraction of the cross-linking agent is 0, i.e., no cross-linking agent is used.

[0079] Example 8:

[0080] Referring to Example 1, step (1) is the same as Example 1, except for step (2): the mass fraction of the cross-linking agent in the mixed solution of the cross-linking agent and the organic electrolyte is 5 wt%.

[0081] Example 9:

[0082] Referring to Example 1, step (1) is the same as Example 1, except for step (2): the mass fraction of the crosslinking agent in the mixed solution consisting of the crosslinking agent and the organic electrolyte is 15 wt%.

[0083] Example 10:

[0084] Referring to Example 1, step (1) is the same as Example 1, except for step (2): the mass fraction of the cross-linking agent in the mixed solution consisting of the cross-linking agent and the organic electrolyte is 20 wt%.

[0085] Example 11

[0086] Refer to Example 1, except that the cross-linked polymer containing amino groups in this embodiment is polyacrylamide, and the remaining steps are the same as in Example 1. The cross-linking test differential thermal scanning curve is shown in FIG. Figure 17 .

[0087] Example 12

[0088] Refer to Example 1, the difference is that the ester-containing functional polymer in this embodiment is polybutyl acrylate, and the remaining steps are the same as in Example 1. The cross-linking test differential thermal scanning curve is shown in FIG. Figure 18 The ester group of polybutyl acrylate and the amine group of polyethylene imine are cross-linked at 130-170°C.

Claims

1. An in-situ gelled double cross-linked polymer electrolyte, characterized in that: A functional polymer containing a nitrile or ester group and a cross-linked polymer containing an amino group are dissolved in N,N-dimethylformamide to prepare a spinning solution, a nanofiber membrane is prepared by an electrostatic spinning process, flattened and then heat-treated at 100-170°C for cross-linking, and a mixed solution of a cross-linking agent and an organic electrolyte is added to perform in-situ gelation to prepare a double cross-linked polymer electrolyte; the mass ratio of the polymer containing a cyano or ester group to the polymer containing an amino group is 1-9:1; the functional polymer containing a nitrile group is selected from polyacrylonitrile or its copolymer with a number average molecular weight of 85,000-150,000; the functional polymer containing an ester group is selected from polyhydroxyethyl acrylate, polybutyl acrylate, polymethyl acrylate The invention relates to a method for preparing an electrostatic spun film comprising: a first electrostatic spun film comprising one or more of a first electrostatic spun film and a second electrostatic spun film; a second electrostatic spun film comprising one or more of branched polyethyleneimine, linear polyethyleneimine, polypropyleneimine, and polyacrylamide; a second electrostatic spun film comprising one or more of 2-hydroxyethyl acrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate; a first electrostatic spun film comprising one or more of a first electrostatic spun film and a second electrostatic spun film; a second ...

2. The in-situ gelled double cross-linked polymer electrolyte according to claim 1, characterized in that: A lithium salt is added to the spinning solution, and the lithium salt is selected from one or more of LiN(SO2CF3)2, LiCF3SO3, and LiN(SO2CF2CF3)2.

3. The in-situ gelled double cross-linked polymer electrolyte according to claim 1 or 2, characterized in that: The amino group-containing polymer is a branched polyethyleneimine with a number average molecular weight of 20,000 to 100,000.

4. The in-situ gelled double cross-linked polymer electrolyte according to claim 1 or 2, characterized in that: The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate; and the organic solvent is selected from one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, vinylene carbonate, propyl acetate, and fluoroethylene carbonate.

5. The in-situ gelled double cross-linked polymer electrolyte according to claim 4, characterized in that: In the organic electrolyte, the molar concentration of the lithium salt is 0.5-2 mol / L.

6. The in-situ gelled double cross-linked polymer electrolyte according to claim 5, characterized in that: The organic electrolyte is 1 mol of LiPF6 dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:

1.

7. Use of the in-situ gelled double cross-linked polymer electrolyte according to claim 1, characterized in that: Applicable to electrochemical energy storage devices or solar cells.

8. The use of the in-situ gelled double cross-linked polymer electrolyte according to claim 7, characterized in that: Electrochemical energy storage devices include lithium-ion batteries, lithium-air batteries, lithium-sulfur batteries, fuel cells, supercapacitors and other metal electrochemical batteries.

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