Polymer composite material, preparation method and application thereof, and lithium ion battery

Abstract

The invention belongs to the technical field of polymer composite materials, and particularly relates to a polymer composite material, a preparation method and application thereof and a lithium ion battery. The polymer composite material provided by the invention comprises a porous base material as well as a first polymer network and a second polymer network which are filled in a pore structure of the porous base material, the first polymer network is formed by heteropoly acid and a polar polymer, and the polar polymer comprises poly (2-ethyl-2-oxazoline), poly (2-methyl-2-oxazoline), poly (N-isopropylacrylamide), polyethylene glycol diacrylate, polyglycolic acid, polycaprolactone, polyacrylamide or polyacrylic acid; the second polymer network is formed by ring opening polymerization of cyclic ether compounds. The polymer composite material provided by the invention has excellent ionic conductivity and good mechanical properties, and can be used as a solid electrolyte for preparing a lithium ion battery.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite material technology, specifically relating to a polymer composite material, its preparation method and application, and lithium-ion batteries. Background Technology

[0002] As the global energy structure shifts towards cleaner and lower-carbon energy, high-energy-density and high-safety energy storage technologies have become the core driving force for electric vehicles, portable electronic devices, and renewable energy storage. While traditional lithium-ion batteries utilize liquid electrolyte systems with a mature industrial chain, they still suffer from significant drawbacks, such as the flammability and leakage risks of organic solvents, and short circuits caused by lithium dendrite growth. Solid-state electrolytes not only fundamentally eliminate the risks of leakage and thermal runaway but also allow for compatibility with high-capacity lithium metal anodes (theoretical specific capacity 3860 mAh / g), thereby increasing battery energy density to over 500 Wh / kg.

[0003] Solid-state electrolytes include inorganic solid-state electrolytes and polymer solid-state electrolytes. Compared to rigid inorganic solid-state electrolytes, polymer solid-state electrolytes achieve ion conduction through the movement of molecular chain segments. They can alleviate stress concentration through the elastic deformation of these molecular chain segments, exhibiting good flexibility and interfacial compatibility, and are easier to fabricate into ultra-thin layers. This allows for ion transport at the micrometer scale, significantly reducing the volume occupied by the electrolyte layer and increasing ionic conductivity and the overall volumetric energy density of the battery. However, the process of ultra-thinning polymer solid-state electrolytes also faces new technical challenges. For example, ultra-thin polymer solid-state electrolytes may weaken their mechanical properties, making them less resistant to the volume expansion phenomenon that occurs in lithium metal batteries under certain conditions, leading to poorer interfacial compatibility and capacity decay. Summary of the Invention

[0004] In view of this, the present invention provides a polymer composite material, its preparation method and application, and a lithium-ion battery. The polymer composite material provided by the present invention has both good mechanical and electrochemical properties and is suitable as a solid electrolyte.

[0005] To address the aforementioned technical problems, the present invention provides a polymer composite material comprising a porous substrate and a first polymer network and a second polymer network filling the pore structure of the porous substrate. The first polymer network is formed from heteropolyacids and polar polymers, including poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly(N-isopropylacrylamide), polyethylene glycol diacrylate, polyglycolic acid, polycaprolactone, polyacrylamide, or polyacrylic acid. The second polymer network is formed by ring-opening polymerization of cyclic ether compounds.

[0006] Preferably, the porous substrate includes a polyethylene film, a polypropylene film, a polyvinylidene fluoride film, a polytetrafluoroethylene film, a polyimide film, or a cellulose film. The heteropolyacids include phosphotungstic acid, phosphotomolybdic acid, silicotungstic ...arsenicmolybdic acid, or borotungstic acid; The cyclic ether compounds include 1,3-dioxolane.

[0007] Preferably, the porosity of the porous substrate is 30-70%; the thickness of the porous substrate is 1-30 μm. The polymer composite material contains 0.5-10% heteropoly acid by mass, 5-30% polar polymer by mass, and 20-50% second polymer network by mass.

[0008] The present invention also provides a method for preparing the polymer composite material described in the above technical solution, comprising the following steps: The heteropolyacid, the polar polymer, and the first solvent are mixed to obtain a mixed solution. A porous substrate is immersed in the mixed solution for adsorption to obtain a primary polymer composite material; The primary polymer composite material and the cyclic ether compound solution are mixed for a second time and then subjected to ring-opening polymerization to obtain the polymer composite material.

[0009] Preferably, the first solvent includes one or more of water, ethanol, methanol, diethyl ether, acetone, acetonitrile, ethyl acetate, xylene, toluene, dichloromethane, chloroform, carbon tetrachloride, benzenehexane, cyclohexane, and N,N-dimethylformamide; The mass ratio of the heteropolyacid to the polar polymer is 0.06 to 10:1; the mass concentration of the heteropolyacid in the mixed solution is 0.01 to 10000 mg / mL. The total mass ratio of the heteropolyacid and polar polymer to the porous substrate is 100~100000:1.

[0010] Preferably, the adsorption temperature is 40~60℃ and the time is 10~48h.

[0011] Preferably, the mass concentration of the cyclic ether compound solution is 30-100%; The mass ratio of the cyclic ether compound in the heteropolyacid and cyclic ether compound solution is 0.01~100:1.

[0012] Preferably, the ring-opening polymerization reaction is carried out at a temperature of 58~62℃ for 5~12h.

[0013] The present invention also provides the application of the polymer composite material described in the above technical solution or the polymer composite material prepared by the preparation method described in the above technical solution in wearable electronic devices, supercapacitors or power batteries.

[0014] The present invention also provides a lithium-ion battery, including a solid electrolyte, wherein the solid electrolyte is the polymer composite material described in the above technical solution or the polymer composite material prepared by the preparation method described in the above technical solution.

[0015] This invention provides a polymer composite material comprising a porous substrate and a first polymer network and a second polymer network filling the pore structure of the porous substrate. The first polymer network is formed by a heteropolyacid and a polar polymer, wherein the polar polymer includes poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly(N-isopropylacrylamide), polyethylene glycol diacrylate, polyglycolic acid, polycaprolactone, polyacrylamide, or polyacrylic acid. The second polymer network is formed by ring-opening polymerization of a cyclic ether compound. In this invention, the polymer composite material is synergistically constructed from a porous substrate and two dynamic supramolecular networks filling the pore structure. The hydrolysis of the polar polymer generates strong electrostatic forces, which in turn generate electrostatic and hydrogen bonding forces with the heteropolyacid. The polar polymer and the heteropolyacid adsorb into the pore structure of the porous substrate to form the first polymer network. The cyclic ether compound filling the pore structure undergoes ring-opening polymerization initiated in situ by the heteropolyacid to form the second polymer network; the first and second polymer networks interpenetrate each other. The polymer composite material provided by this invention has excellent comprehensive properties, and while improving the volumetric energy density, it still has good mechanical properties.

[0016] The polymer composite material provided by this invention is prepared by in-situ polymerization, which has a simple manufacturing process, low equipment requirements, excellent product performance, and broad application prospects. Attached Figure Description

[0017] Figure 1 The infrared spectra of the polyethylene film, primary polymer composite material, and polymer composite material in Example 1 are shown below. Figure 2 The NMR results are for the mixed solution of 1,3-dioxolane and lithium bis(trifluoromethanesulfonylimide) in Example 1 and the polymer composite material prepared in Example 1. Figure 3 The rheological test results are for the composite materials prepared in Example 1 and Comparative Example 1. Figure 4 The results show the cycle performance test results of the lithium-ion battery prepared in Example 1; Figure 5 The results show the rate performance test results of the lithium-ion battery prepared in Example 1. Detailed Implementation

[0018] The present invention provides a polymer composite material comprising a porous substrate and a first polymer network and a second polymer network filling the pore structure of the porous substrate.

[0019] In this invention, the polymer composite material includes a porous substrate, which may include a polyethylene film, a polypropylene film, a polyvinylidene fluoride film, a polytetrafluoroethylene film, a polyimide film, or a cellulose film; the porosity of the porous substrate may be 30-70%, specifically 35%, 40%, 45%, 50%, 55%, 60%, or 65%; the thickness of the porous substrate may be 1-10 μm, specifically 2 μm, 3 μm, 5 μm, 6 μm, 8 μm, or 10 μm.

[0020] In this invention, the polymer composite material includes a first polymer network filling the pore structure of the porous substrate. The first polymer network is formed of a heteropolyacid and a polar polymer, wherein the polar polymer includes poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly(N-isopropylacrylamide), polyethylene glycol diacrylate, polyglycolic acid, polycaprolactone, polyacrylamide, or polyacrylic acid; the heteropolyacid may include phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, silicotungstic acid, arsenicmolybdic acid, or borotungstic acid. As a specific embodiment of this invention, the mass percentage of the heteropolyacid in the polymer composite material can be 0.5% to 30%, specifically 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, or 25%; the mass percentage of the polar polymer can be 5% to 30%, specifically 10%, 13%, 15%, 20%, 23%, 25%, or 28%.

[0021] In this invention, the polymer composite material includes a second polymer network filling the pore structure of the porous substrate, the second polymer network being formed by ring-opening polymerization of a cyclic ether compound; the cyclic ether compound may include 1,3-dioxolane; the mass percentage of the second polymer network in the polymer composite material may be 20-50%, specifically 25%, 30%, 35%, 40% or 45%.

[0022] The polymer composite material provided by this invention has a thin thickness (less than 30 μm) and excellent ion conduction performance; the two polymer networks formed in the pores of the porous substrate not only improve the mechanical properties of the polymer composite material but also improve its rate cycling performance and are more resistant to the growth of lithium dendrites; the lithium-ion battery prepared using it as a solid electrolyte has a high volumetric energy density.

[0023] The present invention also provides a method for preparing the polymer composite material described in the above technical solution, comprising the following steps: The heteropolyacid, the polar polymer, and the first solvent are mixed to obtain a mixed solution. A porous substrate is immersed in the mixed solution for adsorption to obtain a primary polymer composite material; The primary polymer composite material and the cyclic ether compound solution are mixed for a second time and then subjected to ring-opening polymerization to obtain the polymer composite material.

[0024] This invention involves mixing a heteropolyacid, a polar polymer, and a first solvent to obtain a mixed solution. In one specific embodiment, the first solvent may include one or more of water, ethanol, methanol, diethyl ether, acetone, acetonitrile, ethyl acetate, xylene, toluene, dichloromethane, chloroform, carbon tetrachloride, benzenehexane, cyclohexane, and N,N-dimethylformamide, specifically water, ethanol, methanol, diethyl ether, acetone, acetonitrile, ethyl acetate, xylene, toluene, dichloromethane, chloroform, carbon tetrachloride, benzenehexane, cyclohexane, or N,N-dimethylformamide; the water may be deionized water, and the ethanol may be anhydrous ethanol. In embodiments of this invention, the first solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol may be 0.0001~10000:1, or 1~10:1, specifically 1:1.

[0025] As a specific embodiment of the present invention, the first mixing may include the following steps: The heteropolyacid is dissolved in a portion of the first solvent to obtain a heteropolyacid solution; The polar polymer is dissolved in the remaining first solvent to obtain a polar polymer solution; The heteropolyacid solution and the polar polymer solution are mixed for the third time to obtain the mixed solution.

[0026] This invention does not have special requirements on the amount of the first solvent used, as long as it can completely dissolve the heteropolyacid. In one specific embodiment of this invention, the heteropolyacid is dissolved in the first solvent by magnetic stirring for a period of 5 hours or more, or 5 to 10 hours. This invention does not have special limitations on the magnetic stirring, as long as it can completely dissolve the heteropolyacid.

[0027] In one specific embodiment of the present invention, the polar polymer is dissolved in the remaining first solvent by magnetic stirring for a period of 5 hours or more, or 5 to 10 hours. The present invention does not impose any particular limitation on the magnetic stirring method, as long as it can completely dissolve the polar polymer.

[0028] In one specific embodiment of the present invention, the third mixing can be carried out under magnetic stirring conditions; the magnetic stirring time is 4 to 6 hours, specifically 5 hours.

[0029] In one specific embodiment of the present invention, the mass ratio of heteropolyacid to polar polymer in the mixed solution can be 0.06~10:1, or 0.1~5:1, or even 0.15~2:1; specifically, in the embodiments of the present invention, it is 0.067:1, 0.1:1, or 0.15:1. In another specific embodiment of the present invention, the mass concentration of heteropolyacid in the mixed solution can be 0.01~10000 mg / mL, or 1~50 mg / mL, or even 5~10 mg / mL; specifically, in the embodiments of the present invention, it is 5 mg / mL or 7.5 mg / mL.

[0030] After obtaining the mixed solution, the present invention immerses the porous substrate in the mixed solution for adsorption to obtain a primary polymer composite material. As a specific embodiment of the present invention, the mass ratio of the total mass of the heteropolyacid and polar polymer in the mixed solution to the mass of the porous substrate can be 100~100000:1, specifically 200:1, 400:1, 500:1, 600:1, 1000:1, 5000:1, 10000:1, or 50000:1. The present invention does not have a particular limitation on the volume of the mixed solution, as long as it can completely submerge the porous substrate. As a specific embodiment of the present invention, the adsorption temperature can be 40~60℃, specifically 45℃, 50℃, 55℃, or 60℃; the adsorption time can be 10~48h, specifically 15h, 20h, 24h, 30h, 35h, or 40h.

[0031] In this invention, the heteropolyacid and polar polymer are adsorbed in the pore structure of the porous substrate to form a network under electrostatic forces and / or hydrogen bonding forces.

[0032] In one specific embodiment of the present invention, the process after adsorption may further include: drying the adsorbed porous substrate; the drying temperature may be 55~65℃, specifically 60℃; the drying time may be 24 hours or more, or 45~50 hours, specifically 48 hours. The present invention can remove the solvent from the adsorbed porous substrate through drying.

[0033] After obtaining the primary polymer composite material, the present invention further performs ring-opening polymerization on the primary polymer composite material and a solution of cyclic ether compounds to obtain the polymer composite material. The present invention dissolves the cyclic ether compounds in a second solvent to form a cyclic ether compound solution; the cyclic ether compounds may include 1,3-dioxolane; the second solvent may include one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxypropane, methyl formate, methyl acetate, N,N-dimethylacetamide, tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate, specifically ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxypropane, methyl formate, methyl acetate, N,N-dimethylacetamide, tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate. In one specific embodiment of the present invention, the mass concentration of the cyclic ether compound solution can be 30-100%, specifically 50%, 52%, 55%, 60%, 70%, 80%, 90% or 100%; the mass ratio of the heteropolyacid to the cyclic ether compound in the cyclic ether compound solution can be 0.01-100:1, or 0.01-1:10, specifically 0.01:1, 0.03:1, 0.04:1, 0.1:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1 or 1:10.

[0034] In one specific embodiment of the present invention, the temperature of the ring-opening polymerization reaction can be 58~62℃, specifically 60℃; the time of the ring-opening polymerization reaction can be 5~12h, or 9~11h, specifically 6h, 7h, 8h, 9h, 10h or 11h.

[0035] This invention utilizes heteropolyacids to initiate in situ ring-opening polymerization of cyclic ether compounds to form supramolecular networks.

[0036] This invention also provides the application of the polymer composite material described in the above-described technical solutions or the polymer composite material prepared by the preparation method described in the above-described technical solutions in wearable electronic devices, supercapacitors, or power batteries. As a specific embodiment of this invention, the power battery may include a lithium-ion battery.

[0037] The present invention also provides a lithium-ion battery, including a solid electrolyte, wherein the solid electrolyte is the polymer composite material described in the above technical solution or the polymer composite material prepared by the preparation method described in the above technical solution.

[0038] As a specific embodiment of the present invention, the method for preparing the lithium-ion battery may include the following steps: The electrolyte is obtained by mixing a cyclic ether compound, a lithium salt, and a third solvent. The negative electrode, separator, electrolyte and positive electrode are assembled and then subjected to ring-opening polymerization to obtain the lithium-ion battery; the separator is a primary polymer composite material.

[0039] This invention involves mixing a cyclic ether compound, a lithium salt, and a third solvent to obtain an electrolyte. In one specific embodiment, the lithium salt may include lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(oxalate-borate), lithium difluorooxalate-borate, lithium carbonate, lithium nitrate, or lithium chloride. The third solvent may be the same as the second solvent. The molar concentration of the lithium salt in the electrolyte may be 0.001~10 mol / L, or 1~10 mol / L, specifically 0.2 mol / L, 1 mol / L, 2 mol / L, 5 mol / L, or 8 mol / L. In another specific embodiment, the mixing can be carried out under stirring conditions. This invention does not impose any particular limitation on the stirring, as long as complete dissolution is achieved.

[0040] This invention involves assembling a negative electrode, a separator, an electrolyte, and a positive electrode, followed by a ring-opening polymerization reaction to obtain the lithium-ion battery. In one specific embodiment of this invention, the negative electrode may include a lithium sheet, and the positive electrode may include an lithium polymer film (LFP).

[0041] In one specific embodiment of the present invention, the assembly method may include snap-fit ​​assembly, soft-pack assembly, or cylindrical assembly. In another specific embodiment of the present invention, the assembly process may further include: allowing the assembled product to stand for 2-4 hours, specifically 3 hours.

[0042] In one specific embodiment of the present invention, the temperature of the ring-opening polymerization reaction can be 58~62℃, specifically 60℃; the time of the ring-opening polymerization reaction can be 5~12h, or 9~11h, specifically 6h, 7h, 8h, 9h, 10h or 11h.

[0043] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1 S1: Prepare a 10 mg / mL silicotungstic acid solution: Weigh 200 mg of silicotungstic acid, dissolve it completely in 10 mL of deionized water, stir with a magnetic stirrer at room temperature, add 10 mL of anhydrous ethanol during stirring and stir until well mixed; S2: Prepare a 100 mg / mL poly(2-ethyl-2-oxazoline) solution: Weigh 2000 mg of poly(2-ethyl-2-oxazoline) and dissolve it completely in 10 mL of deionized water. Stir with a magnetic stirrer at room temperature. Add 10 mL of anhydrous ethanol during stirring and mix thoroughly. S3: Mix the silicotungstic acid solution and the poly(2-ethyl-2-oxazoline) solution and stir with a magnetic stirrer at room temperature for 5 hours to obtain a mixed solution; S4: Cut a 0.005g polyethylene film with a thickness of 6μm (porosity of 35%) into the required size, immerse it in the mixed solution prepared in S3, and place it in an oven at 60℃ for 48h for adsorption. S5: The polyethylene film adsorbed in S4 is taken out of the mixed solution, laid flat on release paper, and dried in a vacuum oven at 60°C for 24 hours to obtain the primary polymer composite material. S6: Dissolve 0.0287 g (0.001 mol) of lithium bis(trifluoromethanesulfonyl)imide in 0.5 mL of a mixed solution of 1,3-dioxolane and 0.5 mL of dimethyl ethylene glycol (DME), and stir until homogeneous to obtain a mixed electrolyte of lithium bis(trifluoromethanesulfonyl)imide; wherein the molar concentration of lithium bis(trifluoromethanesulfonyl)imide is 1 mol / L; S7: Using the primary polymer composite material in S5 as the separator, coin cells are assembled in an argon-filled glove box in the following order: negative electrode, separator, electrolyte in S6, and positive electrode; the negative electrode is a lithium sheet, and the positive electrode is an LFP. S8: After the battery assembled in S7 is left to stand for 3 hours, it is placed in an oven and subjected to ring-opening polymerization at 60°C for 10 hours to obtain a lithium-ion battery with polymer composite material as solid electrolyte.

[0045] Example 2 The primary polymer composite material and lithium-ion battery were prepared according to the method of Example 1, except that the mass concentration of the poly(2-ethyl-2-oxazoline) solution was 150 mg / mL. 3000 mg of poly(2-ethyl-2-oxazoline) was dissolved in 10 mL of deionized water and stirred at room temperature using a magnetic stirrer. During the stirring process, 10 mL of anhydrous ethanol was added and stirred until homogeneous to obtain a poly(2-ethyl-2-oxazoline) solution with a concentration of 150 mg / mL.

[0046] Example 3 The primary polymer composite material and lithium-ion battery were prepared according to the method of Example 1, except that the mass concentration of the silicotungstic acid solution was 15 mg / mL. 300 mg of silicotungstic acid was fully dissolved in 10 mL of deionized water and stirred at room temperature using a magnetic stirrer. During the stirring process, 10 mL of anhydrous ethanol was added and stirred until homogeneous to obtain a silicotungstic acid solution with a mass concentration of 15 mg / mL.

[0047] Comparative Example 1 0.001 mol of lithium bis(trifluoromethanesulfonyl)imide was dissolved in 1 mL of 1,3-dioxolane and stirred until homogeneous to obtain a solution of lithium bis(trifluoromethanesulfonyl)imide with a molar concentration of 1 mol / L, which was used as the electrolyte. A 6μm thick polyethylene film is used as the separator, a lithium sheet is used as the negative electrode, and an LFP is used as the positive electrode; In an argon-filled glove box, button cells are assembled in the order of negative electrode, separator, electrolyte, and positive electrode to obtain a lithium-ion battery.

[0048] Infrared detection was performed on the polyethylene film, the primary polymer composite material, and the polymer composite material used as a diaphragm in Example 1 to obtain infrared spectra, as shown below. Figure 1 As shown.

[0049] The NMR spectra of the mixed solution of 1,3-dioxolane and lithium bis(trifluoromethanesulfonylimide) in Example 1 and the separator (primary polymer composite material) in the lithium-ion battery were obtained, as shown in the figure. Figure 2 As shown; where DOL+DME represents the prepared electrolyte, and PDOL+DME represents the electrolyte (polymer composite material) after in-situ polymerization, as shown in the NMR test; from Figure 1 and Figure 2 It can be seen that 1,3-dioxolane (DOL) in the electrolyte of Example 1 underwent an in-situ ring-opening polymerization reaction to form a polymer.

[0050] Rheological tests were performed on the in-situ polymer electrolytes (polymer composites) from Example 1 and Comparative Example 1. The test conditions were oscillation mode, temperature 25 degrees Celsius, strain 1%, frequency 1 Hz, and duration 200 s. The rheological mechanical properties of the polymer composites obtained are as follows: Figure 3 As shown; the results for the energy storage modulus (G') and loss modulus (G'') are listed in Table 1.

[0051] Table 1. Rheological properties of the polymeric materials in Example 1 and Comparative Example 1

[0052] Combining Table 1 and Figure 3It can be seen that the G” of the polymer composite material provided by the present invention is significantly higher than that of Comparative Example 1, and the G’ of the polymer composite material provided by the present invention is also significantly higher than that of Comparative Example 1, indicating that the polymer composite material provided by the present invention has excellent mechanical properties.

[0053] The lithium-ion batteries prepared in Examples 1-3 were subjected to cycle performance tests at 30°C, 2.5-3.8V, and 1C. The results are listed in Table 2. Figure 4 The results show the cycle performance test results of the lithium-ion battery prepared in Example 1.

[0054] Table 2 Electrical performance of lithium-ion batteries prepared in Examples 1-3 and Comparative Example 1

[0055] Combine Table 2 and Figure 4 It can be seen that the lithium-ion battery prepared using the polymer composite material provided by the present invention as the separator can stably cycle 200 times under the conditions of positive electrode active material loading of 3mg and 1C rate, with a capacity retention rate of over 94%.

[0056] The lithium-ion batteries prepared in Examples 1-3 (with a positive electrode active material loading of 3 mg) were subjected to rate performance tests at 30°C and 2.5-3.8V. The results are listed in Table 3. Figure 5 The results show the rate performance test results of the lithium-ion battery prepared in Example 1.

[0057] Table 3 Rate performance of the lithium-ion battery prepared in Example 1

[0058] Combined with Table 3 and Figure 5 It can be seen that the lithium-ion battery prepared using the polymer composite material provided by the present invention as the separator can still remain stable under different rate conditions, and after a 5C high rate cycle, its capacity can still remain stable at the initial level after a 0.1C low rate cycle.

[0059] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A polymer composite material, characterized in that, It includes a porous substrate and a first polymer network and a second polymer network filling the pore structure of the porous substrate; The first polymer network is formed from heteropolyacids and polar polymers, including poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly(N-isopropylacrylamide), polyethylene glycol diacrylate, polyglycolic acid, polycaprolactone, polyacrylamide, or polyacrylic acid. The second polymer network is formed by ring-opening polymerization of cyclic ether compounds.

2. The polymer composite material according to claim 1, characterized in that, The porous substrate includes polyethylene film, polypropylene film, polyvinylidene fluoride film, polytetrafluoroethylene film, polyimide film, or cellulose film; The heteropolyacids include phosphotungstic acid, phosphotomolybdic acid, silicotungstic ...arsenicmolybdic acid, or borotungstic acid; The cyclic ether compounds include 1,3-dioxolane.

3. The polymer composite material according to claim 1 or 2, characterized in that, The porosity of the porous substrate is 30-70%; the thickness of the porous substrate is 1-30 μm. The polymer composite material contains 0.5-10% heteropoly acid by mass, 5-30% polar polymer by mass, and 20-50% second polymer network by mass.

4. The method for preparing the polymer composite material according to any one of claims 1 to 3, characterized in that, Includes the following steps: The heteropolyacid, the polar polymer, and the first solvent are mixed to obtain a mixed solution. A porous substrate is immersed in the mixed solution for adsorption to obtain a primary polymer composite material; The primary polymer composite material and the cyclic ether compound solution are mixed for a second time and then subjected to ring-opening polymerization to obtain the polymer composite material.

5. The preparation method according to claim 4, characterized in that, The first solvent includes one or more of water, ethanol, methanol, diethyl ether, acetone, acetonitrile, ethyl acetate, xylene, toluene, dichloromethane, chloroform, carbon tetrachloride, benzenehexane, cyclohexane, and N,N-dimethylformamide; The mass ratio of the heteropolyacid to the polar polymer is 0.06 to 10:1; the mass concentration of the heteropolyacid in the mixed solution is 0.01 to 10000 mg / mL. The total mass ratio of the heteropolyacid and polar polymer to the porous substrate is 100~100000:

1.

6. The preparation method according to claim 4 or 5, characterized in that, The adsorption temperature is 40~60℃ and the time is 10~48h.

7. The preparation method according to claim 4, characterized in that, The mass concentration of the cyclic ether compound solution is 30-100%; The mass ratio of the cyclic ether compound in the heteropolyacid and cyclic ether compound solution is 0.01~100:

1.

8. The preparation method according to claim 4 or 7, characterized in that, The ring-opening polymerization reaction is carried out at a temperature of 58~62℃ for 5~12h.

9. The application of the polymer composite material according to any one of claims 1 to 3 or the polymer composite material prepared by the preparation method according to any one of claims 4 to 8 in wearable electronic devices, supercapacitors or power batteries.

10. A lithium-ion battery, characterized in that, Includes a solid electrolyte, wherein the solid electrolyte is the polymer composite material according to any one of claims 1 to 3 or the polymer composite material prepared by the preparation method according to any one of claims 4 to 8.

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