Composite isolating membrane as well as preparation method and application thereof

Abstract

The invention discloses a composite isolating membrane based on synergistic modification of a porous material and an ionic conductor material and a preparation method of the composite isolating membrane. The composite isolating membrane comprises a base membrane and a coating which is coated on the surface of the base membrane and comprises a porous material and an ion conductor material. The composite isolating membrane has multiple ion transmission paths including ion diffusion or migration transmission, lattice diffusion transmission and ion seepage transmission, the ion transmission efficiency is synergistically enhanced, and the problem that the ion transmission mechanism is single is solved. In addition, the composite separation membrane has accessory functionality, and migration of transition metal can be inhibited. The composite isolating membrane disclosed by the invention is suitable for a high-capacity-density and high-rate battery system, and meets the requirements of battery development.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery separators, and particularly relates to a composite separator based on the synergistic modification of porous materials and ion conductor materials and a preparation method thereof. Background Art

[0002] The separator is one of the key main materials of ion batteries, playing the role of conducting ions and isolating electrons. At present, the separator has been upgraded from the first-generation polyolefin separator (such as PE film, PP film, PP / PE / PP film) to a coated separator (such as alumina / böhmite-coated separator, PVDF-coated separator), and the main function is to improve the thermal shrinkage resistance of the separator, thereby ensuring the safety of battery use. Related technologies can be seen in patents such as CN111509168B and CN207021328U.

[0003] Although the above-mentioned coated separators can improve the safety of the battery, they will also affect the electrochemical performance of the battery. For example, the increase in the thickness of the separator causes an increase in impedance and reduces the charge and discharge efficiency of the battery; the blockage of the separator pores results in hindered ion conduction, etc. Patents CN115810867A and CN116169434B can solve the problem of hindered ion transport to a certain extent through a composite porous material coating, but the ion transport mechanism has not changed, and the ion transport still relies on the electrolyte stored in the porous material and the separator pores. This single ion transport mechanism is still the key limiting the further improvement of ion conductivity.

[0004] In addition, the next-generation separator should develop in the direction of multifunctionality, which is reflected in aspects such as improving ion transport, inhibiting the dissolution and migration of transition metals (especially matching high-nickel cathodes, manganese-based cathodes, and lithium-rich manganese-based cathodes). The next-generation separator is not only a membrane sheet that isolates the positive and negative electrode sheets, but also a semi-solid / solid electrolyte membrane sheet with ion conduction function and a battery component with additional functions. Summary of the Invention

[0005] To address the deficiencies in the prior art and to meet the development needs of the next-generation separator membranes, the present invention provides a composite separator membrane based on the synergistic modification of porous materials and ion conductor materials and a method for preparing the same. By combining porous materials and ion conductor materials, a multi-ion transport mechanism is constructed, such as the ion diffusion or migration transport mechanism in the electrolyte stored in the pores of the porous materials and the base membrane, the lattice diffusion (interstitial transport, vacancy hopping, cooperative migration) in the crystalline ion conductor material, the diffusion mechanism in the amorphous ion conductor material, and the percolation transport mechanism. By synergistically enhancing the ion efficiency through multiple transport mechanisms, the problem of a single ion transport mechanism is overcome, and the ionic conductivity can be effectively improved, enhancing the electrochemical performance of the battery. In addition, by utilizing the pore sieving effect and adsorption effect of the porous materials, the dissolution and migration of transition metals (such as Mn, Ni) in the positive electrode material can be inhibited, improving the battery performance.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a composite separator membrane based on the synergistic modification of porous materials and ion conductor materials, wherein the composite separator membrane comprises a base membrane and a coating applied to the surface of the base membrane; the materials constituting the coating include porous materials and ion conductor materials.

[0008] Further, the materials constituting the coating further include a binder. The content of the binder does not exceed 50 wt% of the coating.

[0009] Further, the surface of the base membrane includes one surface of the base membrane, or two surfaces of the base membrane, or all surfaces of the base membrane.

[0010] Further, the base membrane is selected from one or more of composite membranes of polyolefin membranes, polydimethylsiloxane membranes, polyester membranes, polyamide membranes, polyimide membranes, glass fiber membranes, and non-woven fabrics.

[0011] Further, the thickness of the base membrane is 1-30 μm, the pore diameter is 10-200 nm, and the porosity is 20%-70%.

[0012] Further, the porous material is selected from one or more of metal-organic framework materials, covalent organic framework materials, zeolite molecular sieve materials, and Prussian blue-based materials.

[0013] Further, the particle size of the porous material is 1-1500 nm; the pore diameter of the porous material is 0.1-200 nm; the porosity of the porous material is greater than 30%. Preferably, the particle size of the porous material is 100-600 nm, the pore diameter is 0.5-50 nm, and the porosity is greater than 50%.

[0014] Further, the metal-organic framework compound is selected from one or more of the IRMOF series, ZIF series, MIL series, UIO series, PCN series, HKUST-1 series, MOF-74 series, MOF-801, and MOF-808. Preferably, the metal element in the metal-organic framework compound is selected from one or more of aluminum, magnesium, calcium, zinc, lanthanum, cerium, iron, zirconium, and chromium. Preferably, the organic ligand of the metal-organic framework compound is selected from one or more of terephthalic acid, isophthalic acid, trimellitic acid, fumaric acid, 2-methylimidazole, and derivatives of the above organic ligands.

[0015] Further, the covalent organic framework material is selected from one or more of COF-1, COF-5, COF-102, COF-103, COF-105, COF-108, COF-300, CTF series, and JUC series.

[0016] Further, the Prussian blue-based material is selected from the space porous materials formed by coordination of alkali metal ions, transition metal ions, and cyanide ions (CN - ), ((K / Na / Rb) x M y [Fe(CN)6] z ·nH2O, M = Mn / Fe / Co / Ni / Cu / Zn); preferably, the Prussian blue-based material includes KM[Fe(CN)6] (M = Mn / Fe / Co / Ni / Cu / Zn), K 0.14 Mn 1.43 [Fe(CN)6]·6H2O, K 1.8 Mn 1.1 [Fe(CN)6]·0.27H2O, K 0.1 Cu[Fe(CN)6] 0.7 ·3.8H2O, K 0.1 Ni[Fe(CN)6] 0.7 ·4.1H2O, Na 1.72 Mn[Fe(CN)6], Na 1.4 Mn[Fe(CN)6], Na 0.61 Fe[Fe(CN)6] 0.94 , Rb 0.7 Mn 1.15 [Fe(CN)6]·2.5H2O, etc.

[0017] Further, the zeolite molecular sieve material includes one or more of 3A type, 4A type, 5A type, 10Z type, 13X type, Y type, MCM type, SAPO type, SBA type, and ZSM type.

[0018] Further, the ion conductor material is selected from one or more of ion materials such as fluoride, oxide, sulfide, nitride, phosphide, and halide. Preferably, the oxide ion conductor material includes garnet-type material LLZO / LLZTO, perovskite-type material LLTO, antiperovskite-type material LOC, LiPON type, NASICON type LATP, and LISICON type; preferably, the sulfide ion conductor material includes Li-PS type LPS, argyrodite type LPSCl / LPSI, lithium germanium phosphorus sulfur type LGPS, and Thio-LISICON type.

[0019] Furthermore, the particle size of the ion conductor material is 100-4000 nm. Preferably, the particle size of the ion conductor material is 200-1500 nm.

[0020] Furthermore, the binder is selected from one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, styrene-butadiene latex, chitosan, polyvinyl alcohol, polyvinyl ethyl ether, polyacrylic acid, polymethyl methacrylate, and guar gum.

[0021] Furthermore, the coating has a thickness of 0.5-5 μm.

[0022] Furthermore, the preparation method of the composite isolation membrane based on the synergistic modification of porous materials and ion conductor materials adopts any one of the following methods: blade coating, roller coating, spray coating, spin coating, casting, dipping, filter pressing, suction filtration, and hot pressing.

[0023] The present invention also provides a method for preparing the composite isolation membrane based on the synergistic modification of the porous material and the ion conductor material, which is as follows:

[0024] (1) The porous material, the ion conductor material and the binder are mixed in a certain proportion and fully ground to form a uniform mixture.

[0025] (2) Add the mixture obtained in step (1) into the solvent and stir thoroughly to obtain a uniformly mixed coating slurry.

[0026] (3) The coating slurry is evenly coated on the surface of the base film and placed in an oven for drying to obtain a composite isolation film.

[0027] Furthermore, in the step (1), the amount of the porous material and the ion conductor material added can be mixed in any mass ratio, but does not include the case where either of the two is 0.

[0028] Furthermore, the amount of binder added in step (1) is less than 50% of the mass of the mixture.

[0029] Further, the binder is selected from one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, styrene-butadiene latex, chitosan, polyvinyl alcohol, polyvinyl ethyl ether, polyacrylic acid, polymethyl methacrylate, and guar gum.

[0030] Further, the solvent is selected from one or more of water, methanol, ethanol, isopropanol, ethyl acetate, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0031] The present invention also provides a separator, and the separator is the composite isolation membrane based on the synergistic modification of porous materials and ion conductor materials.

[0032] The present invention also provides a semi-solid electrolyte membrane, and the semi-solid electrolyte membrane is the composite isolation membrane based on the synergistic modification of porous materials and ion conductor materials.

[0033] The present invention also provides an electrochemical device, and the electrochemical device includes a positive electrode sheet, a negative electrode sheet, and the above-mentioned separator or semi-solid electrolyte membrane.

[0034] The present invention also provides an electronic device, and the electronic device includes the above-mentioned electrochemical device.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The composite isolation membrane disclosed in the present invention breaks the current dilemma of a single ion transport mechanism in the coated separator, that is, only relying on the ion diffusion or migration transport mechanism of the electrolyte stored in the pores of the separator. By combining porous materials and ion conductor materials, a multi-ion transport mechanism is constructed. In addition to the ion diffusion or migration transport mechanism in the electrolyte, there are also lattice diffusion transport mechanisms in crystalline ion conductor materials, diffusion mechanisms in amorphous ion conductor materials, and percolation transport mechanisms. Through the above multi-transport mechanisms, the ion transport effect is synergistically enhanced, and the ion conductivity is improved. The above composite isolation membrane provided by the present invention is applicable to high-rate battery systems and meets the development requirements of the next-generation separator.

[0037] (2) The composite isolation membrane disclosed in the present invention utilizes the ion sieving effect and adsorption effect of porous materials to inhibit the dissolution and migration of transition metals (such as Ni, Mn, Co, etc.) in the positive electrode material (especially high-nickel positive electrode, manganese-based positive electrode, and lithium-rich manganese-based positive electrode), can better match high-capacity and high-voltage positive electrode systems, improve the energy density of the battery, and improve the battery performance. Description of the Drawings

[0038] Figure 1 It is a comparison diagram of the discharge capacity of the batteries assembled with the separators prepared in each example and comparative example at 0.2C.

[0039] Figure 2 Discharge capacity comparison chart of the batteries assembled with the separator membranes prepared in each example and comparative example at 1C.

[0040] Figure 3 Discharge capacity comparison chart of the batteries assembled with the separator membranes prepared in each example and comparative example at 4C.

[0041] Figure 4 Effect diagram of the separator membrane prepared in Example 1 for inhibiting transition metal migration.

[0042] Figure 5 Effect diagram of the separator membrane prepared in the comparative example for inhibiting transition metal migration. Detailed implementation manners

[0043] The following examples further illustrate the content of the present invention, but should not be construed as a limitation to the present invention. Without departing from the spirit and essence of the present invention, all other contents obtained by making several equivalent improvements and simple modifications to the present invention belong to the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0044] It should be noted that in the process of preparing the composite separator membrane of the present application, it is necessary to dry the porous material, ion conductor material, and coated separator membrane. The drying temperature and drying time are not limited, and drying is carried out until constant weight is achieved. Preferably, the drying temperature is 60 - 150 °C, and the drying time is 1 - 12 h.

[0045] Example 1

[0046] 1) Place 180 g of MOF material ZIF-8 and 180 g of ion conductor material LATP ((Li 1.3 Al 0.3 Ti 1.7 (PO4)3)) in a vacuum oven, set the drying temperature to 120 °C, and the drying time to 12 hours to remove the moisture and other impurities adsorbed by the materials.

[0047] 2) Mix the dried ZIF-8 and LATP in step 1) with 40 g of polyvinylidene fluoride (PVDF), grind thoroughly and add to 4000 mL of N-methylpyrrolidone, and obtain a uniform slurry through ultrasonic treatment. Among them, the mass ratio of each raw material is: ZIF-8:LATP = 50:50, and the binder PVDF:(PVDF + ZIF-8 + LATP) = 1 - 5:10.

[0048] 3) The mixed slurry obtained in step 2) was evenly scrape-coated on the surface of one side of a 25-μm-thick commercial Celgard 2500 PP film, and then placed in a vacuum oven for drying. The drying temperature was set to 80 °C and dried until constant weight. The obtained separator structure was denoted as: (ZIF-8 + LATP) / / PP.

[0049] 4) On the other side of the commercial Celgard 2500 PP film, the operation of step 3) was repeated to obtain a double-sided coated separator denoted as: (ZIF-8 + LATP) / / PP / / (ZIF-8 + LATP), where the thickness of the single-sided coating was 5 μm.

[0050] Example 2

[0051] In Example 1, the mass ratio of ZIF-8 to LATP was set to ZIF-8:LATP = 99:1, and the remaining steps remained unchanged.

[0052] Example 3

[0053] In Example 1, the mass ratio of ZIF-8 to LATP was set to ZIF-8:LATP = 1:99, and the remaining steps remained unchanged.

[0054] Comparative Example 1

[0055] The commercial 25-μm Celgard 2500 separator was used directly without any treatment.

[0056] Comparative Example 2

[0057] In Example 1, the mass ratio of ZIF-8 to LATP was set to ZIF-8:LATP = 100:0, and the remaining steps remained unchanged, that is, a pure ZIF-8 coated separator ZIF-8 / / PP / / ZIF-8, where the thickness of the single-sided coating was 5 μm.

[0058] Comparative Example 3

[0059] In Example 1, the mass ratio of ZIF-8 to LATP was set to ZIF-8:LATP = 0:100, and the remaining steps remained unchanged, that is, a pure LATP coated separator LATP / / PP / / LATP, where the thickness of the single-sided coating was 5 μm.

[0060] In the above-mentioned examples and comparative examples, the base films used all meet the requirements such as a thickness of 1-30 μm, a pore size of 10-200 nm, and a porosity of 20%-70%; for example, when using the commercial Celgard 2500 PP film as the base film, its porosity is about 55% and the average pore size is 64 nm. The porous materials selected in each example and comparative example are all commonly used porous materials that meet the requirements such as a particle size of 1-1500 nm, a pore size of 0.1-200 nm, and a porosity greater than 30%; for example, the ZIF-8 used in the above-mentioned examples has a pore size of about 0.34 nm and 1.1 nm, and the particle size range is 200-1500 nm; the ion conductor material used in each example is LATP, with a D50 of 429 nm and a D90 of 2260 nm.

[0061] In addition, the inventors of the present application have also repeatedly experimented with other porous materials and ion conductor materials that meet the aforementioned conditions. The porous materials include other series of metal-organic framework materials, the COF series in covalent organic framework materials, zeolite molecular sieve materials, various Prussian blue-based materials, etc.; the ion conductor materials used include fluorides, sulfides, nitrides, phosphides, halides, etc.; any combination of the above shows technical effects equivalent to those of the examples listed in the present application document and achieves the invention purpose of the present application.

[0062] The separator membranes of the above-mentioned examples and comparative examples were tested. The test data of the examples listed below are all the test values obtained from samples where the binder PVDF is 10% of the separator membrane coating quality. The corresponding Comparative Example 2 and Comparative Example 3 also take the test values obtained at this ratio. Only the test values at this ratio are listed below and detailed analysis is carried out only by taking this as an example. However, in the range of PVDF:(PVDF + ZIF-8 + LATP)=1-5:10, the test results show that the synergistic modification of the porous material and the ion conductor material has the same influence and change trend on gas permeability, ionic conductivity, etc.

[0063] Gas permeability test: The gas permeability of the separator is usually expressed by the Gurley value, that is, the time taken for 100 mL of gas to pass through a unit separator membrane area. The size of the Gurley value is related to the porosity and pore connectivity of the separator. A small Gurley value indicates a large porosity and high pore channel connectivity of the separator, small ionic transport resistance, and strong transport ability.

[0064] The separator membranes obtained in each example and comparative example were subjected to gas permeability tests using a PAPT-B01 separator gas permeability tester, and the results are shown in Table 1. Compared with the Gurley value of Comparative Example 1 (base film), the Gurley value of the composite separator membrane obtained in the examples increased slightly, indicating that the gas permeability of the separator membrane decreased slightly due to the influence of the coating, but the influence was very small.

[0065] Table 1 Gurley values of separator membranes obtained in examples and comparative examples

[0066]

[0067] Ionic conductivity test and rate performance test: The separator membranes obtained in the examples and comparative examples were cut into circular pieces with a diameter of 19 mm. Then, a symmetric cell was composed of the separator membrane, LB-229 electrolyte (1 M LiPF6 in EC:DEC = 7:3 vol.%), and a stainless steel electrode sheet, and an AC impedance test (frequency range: 10 -2 -10 5 Hz) was carried out using an electrochemical workstation (CHI760E), and the ionic conductivity was calculated based on the obtained impedance; a battery was assembled with LB-229 electrolyte (1 M LiPF6 in EC:DEC = 7:3 vol.%), NCM523, and a lithium sheet, and tests were carried out under different discharge rates (0.2C / 1C / 4C).

[0068] Table 2 shows the ionic conductivities obtained from tests of different examples and comparative examples. The ionic conductivities of the composite separator membranes in each example are generally better than those of the separator membranes obtained from the comparative examples. Among them, the conductivity of Example 1 is nearly twice that of Comparative Example 1 (Celgard 2500 separator membrane), 1.2 times that of Comparative Example 2 (ZIF-8 / / PP / / ZIF-8), and 2.4 times that of Comparative Example 3 (LATP / / PP / / LATP). The reason for the increase in the ionic conductivity of the composite separator membranes obtained in the examples is the synergistic enhanced ionic transport mechanism possessed by the composite separator membranes, which contains both the diffusion or migration transport mechanism in the electrolyte and the lattice diffusion transport mechanism. Specifically, in the examples, there are both porous ZIF-8 and ionic conductor-type LATP materials. The rich pore structure of ZIF-8 can adsorb and store the electrolyte, enabling the diffusion and migration transport of lithium ions in the stored electrolyte, reducing the transport resistance (such as Examples 1-3 and Comparative Example 2); while the ionic conductor-type LATP realizes the hopping transport of lithium ions through the vacancies in the lattice or the co-migration, achieving the transport of lithium ions in the LATP lattice (such as Examples 1-3 and Comparative Example 3). Compared with the single ionic transport mode of Comparative Examples 1-3, Examples 1-3 are the synergistic effects of the multi-component transport mode. For another example, in Example 2, the addition of a small amount of LATP has a slight increase compared to Comparative Example 2 with simple ionic transport, indicating that there is a synergistic effect between the two transport mechanisms, but the relative synergy is weak; but when the content of the ionic conductor LATP increases, because a continuous transport channel can be formed, the synergistic effect is significantly improved, and thus a greater increase in ionic conductivity is also achieved, such as in Example 1; in Example 3, the mass ratio of LATP:MOF in the coating of the separator membrane is 99:1. When the lattice transport of lithium ions in LATP is dominant, the overall ionic conductivity of the separator membrane is lower than that of the pure MOF coating (Comparative Example 2), but it is about 50% higher than that of the pure LATP coating (Comparative Example 3), indicating that the addition of a small amount of MOF results in a good synergistic effect between the diffusion and migration transport of ions in the pore electrolyte and the lattice transport of LATP, which is the main reason for its significant increase.

[0069] Ionic Conductivities of Separator Membranes Obtained from Examples and Comparative Examples

[0070]

[0071] Figures 1-3The figure shows the change in discharge capacity of the batteries assembled with the separator films obtained in the examples and comparative examples at different rates. As can be seen from the figure, in the case of low-rate discharge (0.2C), the discharge capacities of the examples and comparative examples are not much different. However, as the discharge rate increases, especially at a rate of 4C, the difference in capacity is obvious. This is because in the case of low-rate discharge, lithium ions can be fully transmitted, that is, the ionic conductivities of the examples and comparative examples meet the requirements, and no polarization occurs. Therefore, the discharge capacities are not much different. However, in the case of high-rate discharge, due to insufficient ionic conductivity (such as in the comparative example), the migration rate of lithium ions is not fast enough, causing a polarization effect and resulting in a decrease in discharge capacity. The rate performance of the batteries composed of the separator films obtained in Example 1 and Example 2 is better (the discharge capacity obtained in Example 1 is nearly 20% higher than that obtained in Comparative Example 2), which benefits from the multiple ionic transport paths, making the ionic transport efficiency higher. Secondly, the rate performance of the battery composed of the separator film obtained in Comparative Example 2 is relatively good, mainly due to the high liquid absorption rate and liquid retention rate of the porous material, which reduces the resistance of ions to diffuse or migrate in the electrolyte and improves the rate effect.

[0072] Transition metal migration and adsorption test: Prepare a bis(cyclopentadienyl)nickel mixed solution (the solvent is EC:DEC = 3:7), and the concentration of the mixed solution is 0.01 mol / L, denoted as Solution A. Prepare an EC:DEC = 3:7 mixed solution without Ni ions, denoted as Solution B. Take equal amounts of Solutions A and B and add them to the left and right sides of the H-cell. Use the separator films obtained in Example 1 and Comparative Example 1 as the diaphragms of the H-cell. After standing for 48 h, take out 2 mL from the solutions on both sides respectively, and perform inductively coupled plasma (ICP) testing, and calculate the migration blocking rate of the separator film to Ni ions according to the test results, that is, the ratio of the content of untransferred Ni ions to the total content of Ni ions.

[0073] Figure 4 and Figure 5 are the effect diagrams of the H-cells assembled with the separator films obtained in Example 1 and Comparative Example 1 after 48 h of Ni element migration and adsorption. It can be seen that the solution on the right side of the H-cell assembled with the separator film obtained in Example 1 ( Figure 4 ) shows a light green color, indicating that a small amount of Ni element has migrated to the solution on the right side. And for the H-cell assembled with the separator film obtained in Comparative Example 1 ( Figure 5)The solution color on the right side is relatively darker, indicating that more Ni elements have migrated into the right-side solution. By comparison, it can be seen that the separator membrane obtained in Example 1 has a better effect of inhibiting the migration of transition metals. This is mainly due to the ion sieving effect and adsorption effect of the porous material in the composite separator membrane. The pore size of ZIF-8 is about 0.34 nm, which is smaller than the solvated Ni ions, and can hinder the migration of Ni ions. In addition, the imidazole nitrogen-containing groups exposed due to defects in ZIF-8 can form coordination bonds with transition metal Ni ions through Lewis acid-base interactions, anchoring the Ni ions in the pores, thereby playing a role in blocking and inhibiting the migration of transition metal elements. According to the ICP results, the blocking rate of Ni elements in the separator membrane obtained in Example 1 is nearly 90%, while the blocking rate of the separator membrane obtained in Comparative Example 1 is only about 50%. It can be seen that the composite separator membrane disclosed in the present invention has a good effect of blocking the migration of transition metals.

[0074] In summary, through the composite separator membrane based on the synergistic modification of porous materials and ion conductor materials disclosed in this patent, multiple ion transport paths can be obtained, greatly improving the ionic conductivity and ion transport efficiency, which is beneficial to the improvement of the rate performance of the battery and meets the application requirements of high-rate batteries. In addition, the composite separator membrane disclosed in this patent also has accessory functionality, can effectively inhibit the migration of transition metal elements, can better match the high-capacity and high-voltage cathode system, and is beneficial to improving the energy density of the battery.

Claims

1. A composite separator, characterized in that: The composite isolation membrane includes a base membrane and a coating applied on the surface of the base membrane; wherein the coating includes a porous material and an ion conductor material; the ion transport mechanism of the composite isolation membrane is based on the synergistic mechanism of the two, namely: a transport mechanism of ion diffusion and migration through an electrolyte stored in the porous material, and a diffusion mechanism of ions in the ion conductor material, and the two mechanisms act synergistically on the transport of ions.

2. The composite separator film according to claim 1, wherein: The base film is selected from one or more composite films of polyolefin films, polydimethylsiloxane films, polyester films, polyamide films, polyimide films, glass fiber films, and non-woven fabrics.

3. The composite separator film according to claim 1, wherein: The porous material is selected from one or more of metal organic framework materials, covalent organic framework materials, zeolite molecular sieve materials and Prussian blue materials.

4. A composite separator film according to claim 1, characterized in that: The ion conductor material is selected from one or more of fluoride, oxide, sulfide, nitride, phosphide and halide ion conducting materials.

5. A composite separator film according to claim 1, characterized in that: The coating also includes a binder.

6. The composite isolation film according to claim 5, characterized in that: The binder accounts for less than 50% by mass in the coating.

7. A composite separator film according to claim 1, characterized in that: The coating thickness is 0.5-5 μm.

8. A method for preparing a composite separator membrane according to any one of claims 1 to 7, characterized in that: The composite isolation membrane is coated by any of the following methods: scraping, roller coating, spraying, spin coating, casting, dipping, filter pressing, suction filtration, and hot pressing.

9. The preparation method of a composite separator film according to claim 8, characterized in that: The preparation method adopts a scraping coating method, and the specific steps are as follows: (1) mixing the porous material, the ion conductor material and the binder in a certain proportion, and grinding them sufficiently to make them uniformly mixed to form a mixture; (2) adding the mixture obtained in step (1) into a solvent and stirring thoroughly to obtain a uniformly mixed coating slurry; (3) The coating slurry is evenly coated on the surface of the base film and placed in an oven for drying to obtain a composite isolation film.

10. The preparation method of a composite separator film according to claim 9, characterized in that: The amount of the porous material and the ion conductor material added in step (1) can be mixed in any mass ratio, but does not include the case where the porous material or the ion conductor material is 0; the amount of the binder added is less than 50% of the total mass of the mixture in step 1); The binder is selected from one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, styrene-butadiene latex, chitosan, polyvinyl alcohol, polyvinyl ethyl ether, polyacrylic acid, polymethyl methacrylate, and guar gum; The solvent is selected from one or more of water, methanol, ethanol, isopropanol, ethyl acetate, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide.

11. A battery separator, characterized in that: The battery separator is the composite separator according to any one of claims 1 to 7.

12. A semi-solid electrolyte membrane, characterized in that: The semi-solid electrolyte membrane is the composite isolation membrane according to any one of claims 1 to 7.

13. An electrochemical device, characterized in that: The electrochemical device comprises a positive electrode sheet, a negative electrode sheet, a battery separator according to claim 11 or a semi-solid electrolyte membrane according to claim 12.

14. An electronic device, characterized in that: The electronic device comprises the electrochemical device according to claim 13.

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