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

Abstract

The application belongs to the technical field of polymer composites, 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 application comprises a porous base material, and a first polymer network and a second polymer network filled in a pore structure of the porous base material; the first polymer network is formed by a heteropoly acid and a polar polymer, and the polar polymer comprises poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly N-isopropyl acrylamide, 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. The polymer composite material provided by the application has excellent ion conduction performance and good mechanical properties, and can be used as a solid-state electrolyte to prepare a lithium ion battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer composites, and particularly relates to a polymer composite, a preparation method and application thereof, and a lithium ion battery. BACKGROUND

[0002] With the transformation of global energy structure to clean and low-carbon, high-energy density and high-safety energy storage technology has become the core driving force for promoting electric vehicles, portable electronic devices and renewable energy storage. Although the traditional lithium ion battery adopts a mature industrial chain of liquid electrolyte system, it still has defects that cannot be ignored, such as flammable organic solvent, easy leakage, short circuit caused by lithium dendrite growth, etc. Solid-state electrolyte can not only fundamentally eliminate the leakage and thermal runaway hazards, but also can be compatible with high-capacity lithium metal negative electrode (theoretical specific capacity 3860 mAh / g), thereby improving the battery energy density to more than 500 Wh / kg.

[0003] Compared with rigid inorganic solid-state electrolyte, polymer solid-state electrolyte realizes ion conduction through the movement of molecular chain segments, can relieve stress concentration through the elastic deformation of molecular chain segments, has good flexibility and interface compatibility, is easier to process into ultra-thin, realizes ion transmission on the micron scale, thereby greatly reducing the volume occupied by the electrolyte layer, and improving the ion conductivity and the overall volume energy density of the battery. However, in the process of ultra-thinning of the polymer solid-state electrolyte, new technical problems will be faced, for example, the ultra-thin polymer solid-state electrolyte will weaken its mechanical properties, and under certain conditions, it is difficult to resist the volume expansion phenomenon of lithium metal battery in operation, resulting in poor interface compatibility and capacity decay. SUMMARY

[0004] Therefore, the present application provides a polymer composite, a preparation method and application thereof, and a lithium ion battery. The polymer composite provided by the present application has good mechanical properties and electrochemical properties, and is suitable as a solid-state electrolyte.

[0005] In order to solve the above technical problems, the present application provides a polymer composite, which comprises a porous substrate and a first polymer network and a second polymer network filled in the pore structure of the porous substrate.

[0006] The first polymer network is formed by a heteropoly acid and a polar polymer, and the polar polymer comprises poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly N-isopropyl acrylamide, polyethylene glycol diacrylate, polyglycolic acid, polycaprolactone, polyacrylamide or polyacrylic acid.

[0007] The second polymer network is formed by ring ether compound ring-opening polymerization.

[0008] Preferably, the porous substrate comprises a polyethylene film, a polypropylene film, a polyvinylidene fluoride film, a polytetrafluoroethylene film, a polyimide film or a cellulose film.

[0009] The heteropoly acid comprises phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, silicomolybdic acid, arsenic molybdate or borotungstate.

[0010] The cyclic ether compound comprises 1,3-dioxolane.

[0011] Preferably, the porosity of the porous substrate is 30-70%; the thickness of the porous substrate is 1-30 μm.

[0012] The mass percentage of the heteropoly acid in the polymer composite is 0.5-10%, the mass percentage of the polar high polymer is 5-30%, and the mass percentage of the second polymer network is 20-50%.

[0013] The application also provides a preparation method of the polymer composite according to the above technical solution, comprising the following steps:

[0014] The heteropoly acid, the polar high polymer and the first solvent are mixed to obtain a mixed solution;

[0015] The porous substrate is immersed in the mixed solution for adsorption to obtain a primary polymer composite;

[0016] The primary polymer composite and a cyclic ether compound solution are secondly mixed to perform ring-opening polymerization to obtain the polymer composite.

[0017] Preferably, the first solvent comprises one or more of water, ethanol, methanol, diethyl ether, acetone, acetonitrile, ethyl acetate, dimethylbenzene, toluene, dichloromethane, chloroform, carbon tetrachloride, benzene hexane, cyclohexane and N,N-dimethylformamide.

[0018] The mass ratio of the heteropoly acid and the polar high polymer is 0.06-10:1; the mass concentration of the heteropoly acid in the mixed solution is 0.01-10000 mg / mL.

[0019] The mass ratio of the total mass of the heteropoly acid and the polar high polymer to the mass of the porous substrate is 100-100000:1.

[0020] Preferably, the adsorption temperature is 40-60°C, and the time is 10-48 h.

[0021] Preferably, the mass concentration of the cyclic ether compound solution is 30-100%.

[0022] The mass ratio of the heteropoly acid to the cyclic ether compound in the cyclic ether compound solution is 0.01-100:1.

[0023] Preferably, the temperature of the ring-opening polymerization reaction is 58-62℃, and the time is 5-12h.

[0024] The application further provides application of the polymer composite material in the above technical solution or the polymer composite material prepared by the preparation method in the above technical solution in a wearable electronic device, a super capacitor or a power battery.

[0025] The application further provides a lithium ion battery comprising a solid electrolyte, and the solid electrolyte is the polymer composite material in the above technical solution or the polymer composite material prepared by the preparation method in the above technical solution.

[0026] The application provides a polymer composite material, comprising a porous substrate and a first polymer network and a second polymer network filled in a pore structure of the porous substrate; the first polymer network is formed by a heteropoly acid and a polar polymer, and the polar polymer comprises poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly N-isopropyl acrylamide, 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 the application, the polymer composite material is constructed by the porous substrate and the two dynamic supramolecular networks filled in the pore structure, and the polar polymer hydrolysis generates strong electrostatic force, electrostatic interaction force and hydrogen bond interaction force with the heteropoly acid, and the polar polymer and the heteropoly acid are adsorbed in the pore structure in the porous substrate to form the first polymer network. The cyclic ether compound filled in the pore structure is in-situ initiated by the heteropoly acid to form the second polymer network by ring-opening polymerization; and the first polymer network and the second polymer network are interpenetrated. The polymer composite material provided by the application has excellent comprehensive performance, and has good mechanical properties while improving the volume energy density.

[0027] The polymer composite material provided by the application is prepared by an in-situ polymerization method, has simple manufacturing process, low equipment requirement, excellent product performance and wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The infrared spectra of the polyethylene film, the primary polymer composite material and the polymer composite material in Example 1 are shown in the following figure;

[0029] Figure 2 The nuclear magnetic detection results of the mixed solution of 1,3-dioxolane and lithium bis(trifluoromethanesulfonyl)imide in Example 1 and the polymer composite material prepared in Example 1 are shown in the following figure;

[0030] Figure 3Rheological mechanics test results of the composite material prepared for Example 1 and Comparative Example 1;

[0031] Figure 4 Cycling performance test results of the lithium ion battery prepared for Example 1;

[0032] Figure 5 Rate performance test results of the lithium ion battery prepared for Example 1. DETAILED DESCRIPTION

[0033] The present application provides a polymer composite material, comprising a porous substrate and a first polymer network and a second polymer network filled in the pore structure of the porous substrate.

[0034] In the present application, the polymer composite material comprises a porous substrate, which can comprise 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 can be 30-70%, which can be specifically 35%, 40%, 45%, 50%, 55%, 60% or 65%; the thickness of the porous substrate can be 1-10 μm, which can be specifically 2 μm, 3 μm, 5 μm, 6 μm, 8 μm or 10 μm.

[0035] In the present application, the polymer composite material comprises a first polymer network filled in the pore structure of the porous substrate, which is formed by a heteropoly acid and a polar polymer, the polar polymer comprising poly(2-ethyl-2-oxazoline), poly(2-methyl-2-oxazoline), poly N-isopropyl acrylamide, polyethylene glycol diacrylate, polyglycolic acid, polycaprolactone, polyacrylamide or polyacrylic acid; the heteropoly acid can comprise phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, silicomolybdic acid, arsenomolybdic acid or borotungstic acid. As a specific embodiment of the present application, the mass percentage content of the heteropoly acid in the polymer composite material can be 0.5-30%, which can be specifically 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23% or 25%; the mass percentage content of the polar polymer can be 5-30%, which can be specifically 10%, 13%, 15%, 20%, 23%, 25% or 28%.

[0036] In the present application, the polymer composite material comprises a second polymer network filled in the pore structure of the porous substrate, which is formed by ring ether compound ring-opening polymerization; the ring ether compound can comprise 1,3-dioxolane; the mass percentage content of the second polymer network in the polymer composite material can be 20-50%, which can be specifically 25%, 30%, 35%, 40% or 45%.

[0037] The polymer composite provided by the application has a thin thickness (30 microns or less) and excellent ion conduction performance; the two polymer networks formed in the pores of the porous substrate improve the mechanical properties of the polymer composite and also improve the rate cycle performance, and can better resist the growth of lithium dendrites; and the lithium ion battery prepared by using the polymer composite as a solid-state electrolyte has a high volume energy density.

[0038] The application further provides a preparation method of the polymer composite.

[0039] The heteropoly acid, the polar polymer and the first solvent are first mixed to obtain a mixed solution.

[0040] The porous substrate is immersed in the mixed solution for adsorption to obtain a primary polymer composite.

[0041] The primary polymer composite and a cyclic ether compound solution are second mixed to perform ring-opening polymerization to obtain the polymer composite.

[0042] As a specific embodiment of the application, the first solvent can include one or more of water, ethanol, methanol, diethyl ether, acetone, acetonitrile, ethyl acetate, dimethylbenzene, methylbenzene, dichloromethane, chloroform, carbon tetrachloride, benzene hexane, cyclohexane and N,N-dimethylformamide, and can specifically be water, ethanol, methanol, diethyl ether, acetone, acetonitrile, ethyl acetate, dimethylbenzene, methylbenzene, dichloromethane, chloroform, carbon tetrachloride, benzene hexane, cyclohexane or N,N-dimethylformamide; the water can be deionized water, and the ethanol can be anhydrous ethanol. In the embodiment of the application, the first solvent is a mixed solvent of water and ethanol, and the volume ratio of the water to the ethanol can be 0.0001-10000:1, and can also be 1-10:1, and can specifically be 1:1.

[0043] As a specific embodiment of the application, the first mixing can include the following steps:

[0044] The heteropoly acid is dissolved in part of the first solvent to obtain a heteropoly acid solution;

[0045] The polar polymer is dissolved in the remaining first solvent to obtain a polar polymer solution;

[0046] The heteropoly acid solution and the polar polymer solution are third mixed to obtain the mixed solution.

[0047] The present application does not have special requirements for the amount of the partial first solvent, as long as the heteropoly acid can be completely dissolved. As a specific embodiment of the present application, the way of dissolving the heteropoly acid in the partial first solvent is magnetic stirring, and the time of the magnetic stirring is more than 5 hours, and can be 5-10 hours. The present application does not have special limitations on the magnetic stirring, as long as the heteropoly acid can be completely dissolved.

[0048] As a specific embodiment of the present application, the way of dissolving the polar polymer in the remaining first solvent is magnetic stirring, and the time of the magnetic stirring is more than 5 hours, and can be 5-10 hours. The present application does not have special limitations on the magnetic stirring, as long as the polar polymer can be completely dissolved.

[0049] As a specific embodiment of the present application, the third mixing can be carried out under the condition of magnetic stirring; and the time of the magnetic stirring is 4-6 hours, and can be specifically 5 hours.

[0050] As a specific embodiment of the present application, the mass ratio of the heteropoly acid and the polar polymer in the mixed solution can be 0.06-10:1, and can be 0.1-5:1, and can be further 0.15-2:1; and in the examples of the present application, it is specifically 0.067:1, 0.1:1 or 0.15:1. As a specific embodiment of the present application, the mass concentration of the heteropoly acid in the mixed solution can be 0.01-10000 mg / mL, and can be 1-50 mg / mL, and can be further 5-10 mg / mL; and in the examples of the present application, it is specifically 5 mg / mL or 7.5 mg / mL.

[0051] After obtaining the mixed solution, the present application immerses the porous substrate in the mixed solution for adsorption to obtain a primary polymer composite material. As a specific embodiment of the present application, the mass ratio of the total mass of the heteropoly acid and the polar polymer in the mixed solution to the mass of the porous substrate can be 100-100000:1, and can be specifically 200:1, 400:1, 500:1, 600:1, 1000:1, 5000:1, 10000:1 or 50000:1. The present application does not have special limitations on the volume of the mixed solution, as long as the porous substrate can be immersed. As a specific embodiment of the present application, the temperature of the adsorption can be 40-60°C, and can be specifically 45°C, 50°C, 55°C or 60°C; and the time of the adsorption can be 10-48 hours, and can be specifically 15 hours, 20 hours, 24 hours, 30 hours, 35 hours or 40 hours.

[0052] In the present application, the heteropoly acid and the polar polymer are adsorbed in the pore structure of the porous substrate to form a network under the electrostatic force and / or hydrogen bond force.

[0053] As a specific embodiment of the present application, the adsorption can further include: drying the porous substrate after adsorption; the drying temperature can be 55-65 DEG C, and can be specifically 60 DEG C; the drying time can be more than 24 hours, and can be specifically 45-50 hours, and can be specifically 48 hours. The present application can remove the solvent in the porous substrate after adsorption by drying.

[0054] After obtaining the primary polymer composite, the present application secondly mixes the primary polymer composite and a cyclic ether compound solution to perform ring-opening polymerization to obtain the polymer composite. The present application dissolves the cyclic ether compound in a second solvent to form the cyclic ether compound solution; the cyclic ether compound can include 1,3-dioxolane; the second solvent can 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, and can be 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. As a specific embodiment of the present application, the mass concentration of the cyclic ether compound solution can be 30-100%, and can be specifically 50%, 52%, 55%, 60%, 70%, 80%, 90% or 100%; the mass ratio of the heteropoly acid and the cyclic ether compound in the cyclic ether compound solution can be 0.01-100:1, and can be specifically 0.01-1:10, and can be 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.

[0055] As a specific embodiment of the present application, the temperature of the ring-opening polymerization reaction can be 58-62 DEG C, and can be specifically 60 DEG C; the time of the ring-opening polymerization reaction can be 5-12 hours, and can be specifically 9-11 hours, and can be specifically 6 hours, 7 hours, 8 hours, 9 hours, 10 hours or 11 hours.

[0056] The present application can form a supramolecular network by in-situ initiating the ring-opening polymerization reaction of the cyclic ether compound by the heteropoly acid.

[0057] The present application also provides the application of the polymer composite in the above technical solution or the polymer composite prepared by the preparation method in the above technical solution in wearable electronic devices, supercapacitors or power batteries. As a specific embodiment of the present application, the power battery can include a lithium ion battery.

[0058] The application further provides a lithium ion battery comprising a solid electrolyte, wherein the solid electrolyte is the polymer composite according to the above technical solution or the polymer composite prepared by the preparation method according to the above technical solution.

[0059] As a specific embodiment of the application, the preparation method of the lithium ion battery can comprise the following steps:

[0060] Mixing a cyclic ether compound, a lithium salt and a third solvent to obtain an electrolyte;

[0061] Assembling the negative electrode, the separator, the electrolyte and the positive electrode and then performing ring-opening polymerization to obtain the lithium ion battery, wherein the separator is a primary polymer composite.

[0062] As a specific embodiment of the application, the lithium salt can comprise lithium bistrifluoromethanesulfonimide, lithium bisfluorosulfonimide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium carbonate, lithium nitrate or lithium chloride; the third solvent can be consistent with the second solvent; the molar concentration of the lithium salt in the electrolyte can be 0.001-10 mol / L, and can also be 1-10 mol / L, and can be specifically 0.2 mol / L, 1 mol / L, 2 mol / L, 5 mol / L or 8 mol / L. As a specific embodiment of the application, the mixing can be performed under stirring, and the application does not have special limitations on the stirring, as long as complete dissolution can be achieved.

[0063] As a specific embodiment of the application, the negative electrode can comprise a lithium sheet, and the positive electrode can comprise LFP.

[0064] As a specific embodiment of the application, the assembling can comprise buckle assembling, soft package assembling or cylindrical assembling. As a specific embodiment of the application, the assembling can further comprise: placing the assembled product for 2-4 h, and can be specifically 3 h.

[0065] As a specific embodiment of the application, the temperature of the ring-opening polymerization can be 58-62 DEG C, and can be specifically 60 DEG C; the time of the ring-opening polymerization can be 5-12 h, and can also be 9-11 h, and can be specifically 6 h, 7 h, 8 h, 9 h, 10 h or 11 h.

[0066] In order to further illustrate the application, the technical solutions provided by the application are described in detail below in combination with embodiments, but they should not be understood as limiting the scope of protection of the application.

[0067] Example 1

[0068] S1: Prepare a 10 mg / mL solution of silicotungstic acid: weigh 200 mg of silicotungstic acid, fully dissolve it in 10 mL of deionized water, stir at room temperature using a magnetic stirrer, and during stirring, add 10 mL of anhydrous ethanol and stir to mix evenly;

[0069] S2: Prepare a 100 mg / mL solution of poly(2-ethyl-2-oxazoline): weigh 2000 mg of poly(2-ethyl-2-oxazoline), fully dissolve it in 10 mL of deionized water, stir at room temperature using a magnetic stirrer, and during stirring, add 10 mL of anhydrous ethanol and stir to mix evenly;

[0070] S3: Mix the silicotungstic acid solution and the poly(2-ethyl-2-oxazoline) solution, stir at room temperature using a magnetic stirrer for 5 h, and obtain a mixed solution;

[0071] S4: Cut a 0.005 g polyethylene film with a thickness of 6 μm (porosity of 35%) into the required size, and immerse it in the mixed solution prepared in S3, and place it in an oven at 60°C for 48 h of adsorption;

[0072] S5: Take out the polyethylene film after adsorption in S4 from the mixed solution, place it flat on a release paper, and place it in a vacuum oven at 60°C for 24 h of drying, and obtain a primary polymer composite material;

[0073] S6: Dissolve 0.0287 g (0.001 mol) of lithium bis(trifluoromethanesulfonyl)imide in a mixed solution of 0.5 mL of 1,3-dioxolane and 0.5 mL of ethylene glycol dimethyl ether (DME), mix and stir until uniform, and obtain a mixed electrolyte of lithium bis(trifluoromethanesulfonyl)imide; wherein the molar concentration of lithium bis(trifluoromethanesulfonyl)imide is 1 mol / L;

[0074] S7: Use the primary polymer composite material in S5 as a separator, assemble a coin cell in the order of negative electrode, separator, electrolyte in S6, and positive electrode in an argon-filled glove box; the negative electrode is a lithium sheet, and the positive electrode is LFP;

[0075] S8: After 3 h of standing, place the battery assembled in S7 in an oven at 60°C for 10 h of ring-opening polymerization reaction, and obtain a lithium ion battery with a polymer composite material as a solid-state electrolyte.

[0076] Example 2

[0077] The primary polymer composite 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, stirring was performed at room temperature using a magnetic stirrer, 10 mL of anhydrous ethanol was added during stirring and mixed uniformly to obtain a poly(2-ethyl-2-oxazoline) solution with a concentration of 150 mg / mL.

[0078] Example 3

[0079] The primary polymer composite 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, stirring was performed at room temperature using a magnetic stirrer, 10 mL of anhydrous ethanol was added during stirring and mixed uniformly to obtain a poly(2-ethyl-2-oxazoline) solution with a concentration of 150 mg / mL.

[0080] Comparative Example 1

[0081] 0.001 mol of lithium bis(trifluoromethanesulfonyl)imide was dissolved in 1 mL of 1,3-dioxolane, and the mixture was stirred until uniform to obtain a solution of lithium bis(trifluoromethanesulfonyl)imide with a molar concentration of 1 mol / L, which was used as an electrolyte;

[0082] A polyethylene film with a thickness of 6 μm was used as a separator, lithium sheet was used as a negative electrode, and LFP was used as a positive electrode.

[0083] A coin cell was assembled in an argon-filled glove box in the order of negative electrode, separator, electrolyte, and positive electrode to obtain a lithium ion battery.

[0084] The polyethylene film, the primary polymer composite, and the polymer composite used as a separator in Example 1 were subjected to infrared detection, and the infrared spectrum was obtained as shown in Figure 1 .

[0085] The mixed solution of 1,3-dioxolane and lithium bis(trifluoromethanesulfonyl)imide in Example 1 and the separator (primary polymer composite) in the lithium ion battery were subjected to nuclear magnetic detection, and the spectrum was obtained as shown in Figure 2 ; wherein DOL+DME represents the prepared electrolyte, and PDOL+DME represents the in-situ polymerized electrolyte (polymer composite) subjected to nuclear magnetic testing; it can be seen from Figure 1 and Figure 2 that the 1,3-dioxolane (DOL) in the electrolyte of Example 1 has undergone in-situ ring-opening polymerization to form a polymer.

[0086] Rheological test was carried out on the polymer electrolyte (polymer composite) in situ polymerized in Example 1 and Comparative Example 1, with the test conditions being oscillation mode, temperature 25 degrees, strain 1%, frequency 1 Hz, and duration 200 s, and the obtained rheological mechanical property test results of the polymer composite are shown in FIG. 1, wherein the results of storage modulus (G') and loss modulus (G'') are listed in Table 1. Figure 3

[0087] Table 1 Rheological properties of the polymer composite of Example 1 and Comparative Example 1

[0088]

[0089] In combination with Table 1 and Figure 3 It can be seen that the G'' of the polymer composite provided by the present application is significantly higher than that of Comparative Example 1, and the G' of the polymer composite provided by the present application is also significantly higher than that of Comparative Example 1, indicating that the polymer composite provided by the present application has excellent mechanical properties.

[0090] The lithium ion battery prepared in Example 1~3 was subjected to cycle performance test under the conditions of 30℃, 2.5~3.8V, and 1C, and the results are listed in Table 2, Figure 4 The cycle performance test results of the lithium ion battery prepared in Example 1.

[0091] Table 2 Electrical properties of the lithium ion battery prepared in Example 1~3 and Comparative Example 1

[0092]

[0093] In combination with Table 2 and Figure 4 It can be seen that the lithium ion battery prepared by using the polymer composite provided by the present application as the separator can be stably cycled for 200 cycles with the capacity retention rate being above 94% under the conditions of 3mg of positive electrode active material loading and 1C rate.

[0094] The lithium ion battery prepared in Example 1~3 (with the positive electrode active material loading being 3mg) was subjected to rate performance test under the conditions of 30℃ and 2.5~3.8V, and the results are listed in Table 3, Figure 5 The rate performance test results of the lithium ion battery prepared in Example 1.

[0095] Table 3 Rate performance of the lithium ion battery prepared in Example 1

[0096]

[0097] In combination with Table 3 and Figure 5 ​It can be seen that the lithium ion battery prepared by using the polymer composite material provided by the application as a separator can still maintain stability under different rate conditions, and after high-rate 5C cycling, the capacity can still be stabilized at the initial degree during low-rate 0.1C cycling.

[0098] Although the above embodiment has made a detailed description of the application, it is only a part of the embodiments of the application, but not all the embodiments, and other embodiments can be obtained according to the embodiment without creativity, and these embodiments all belong to the protection scope of the application.

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; The method for preparing the polymer composite material includes the following steps: The heteropoly acid, the polar polymer, and the first solvent are mixed to obtain a mixed solution; the first solvent includes water. 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.

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 further includes one or more of 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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