Battery separator capable of absorbing water and acid and manufacturing method thereof, pole piece capable of absorbing water and acid, battery

Abstract

The present invention provides a battery separator capable of absorbing water and acid, a manufacturing method thereof, a polar piece capable of absorbing water and acid, and a battery. By knife-coating a metal-organic framework material onto the battery separator, a composite separator capable of efficiently absorbing water and acid is manufactured as the battery separator. On the one hand, the battery separator capable of absorbing water and acid can effectively adsorb impurities such as water and acid in the battery, further improving the cycle stability of the battery. On the other hand, the battery separator capable of absorbing water and acid can effectively reduce the water control conditions during the battery assembly process, thereby effectively reducing costs.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from a Chinese patent application filed on September 20, 2022, with application number 202211145859.2, entitled "Water and acid absorbing battery separator and manufacturing method thereof, water and acid absorbing pole piece, battery," and from a Chinese patent application filed on September 20, 2022, with application number 202222492408.8, entitled "Composite battery separator and battery," the entire contents of which are hereby incorporated by reference. FIELD OF THE INVENTION The present invention relates to the field of batteries, and more particularly to water and acid absorbing battery separators and methods for making the same, water and acid absorbing pole pieces, and batteries. [Background technology]

[0002] The electrolyte in a battery is prone to decomposition by absorbing water vapor from the air, producing acidic substances, which deteriorates the battery's cycle characteristics. Therefore, the assembly of a lithium battery must generally be carried out in a dry environment, such as a dry room or glove box.

[0003] However, it is difficult to completely remove trace amounts of water and hydrogen fluoride from the electrolyte, and trace amounts of water and acid currently present in batteries significantly affect the deterioration of battery characteristics, particularly those of high-nickel positive electrodes. Furthermore, strict control of water during the battery assembly process, including the process of disposing the electrolyte, requires high costs.

[0004] Therefore, how to control the water content of a battery to improve the battery cycle characteristics is a technical problem that must be solved urgently by those skilled in the art. Summary of the Invention [Problem to be solved by the invention]

[0005] The technical problem that the embodiments of the present invention aim to solve is how to control the water content of a battery to improve the battery cycle characteristics. [Means for solving the problem]

[0006] On the one hand, an embodiment of the present invention provides a battery separator capable of absorbing water and acid, the battery separator capable of absorbing water and acid includes a substrate film and a metal-organic framework material, the metal-organic framework material being dispersed on at least one surface of the substrate film.

[0007] Optionally, the metal organic framework material has a specific surface area of ​​>900 m 2 / g, and preferably the specific surface area of ​​the metal-organic framework material is >2400 m 2 / g.

[0008] Optionally, the metal organic framework material has a pore size range of 0.92 nm to 3.5 nm.

[0009] As an option, the battery separator capable of absorbing water and acid includes a separator body and a metal-organic framework material layer, the separator body being made of the base film, the metal-organic framework material layer being made of the metal-organic framework material, the metal-organic framework material layer being attached to at least one surface of the separator body, and the thickness of the metal-organic framework material layer being in the range of 15 μm to 75 μm.

[0010] Optionally, the water and acid absorbing battery separator has a water absorption of 800 ppm or less.

[0011] Optionally, the metal-organic framework material layer is adhered to the separator body.

[0012] Optionally, the battery's composite separator has an acid absorption of 1107 ppm or less.

[0013] Optionally, the metal organic framework material is at least one selected from HKUST-1, MOF-801, MIL-101, MOF-303, and UiO-66.

[0014] Optionally, the liner material is selected from polyolefin, fiberglass, or polyimide.

[0015] On the other hand, embodiments of the present invention further provide a method for manufacturing a battery separator capable of absorbing water and acid, the method comprising: Step (1) of preparing a paste by mixing a metal-organic framework material and a binder in a mass ratio of 5:5 to 9:1; and (2) applying the paste onto an undercoat film and subjecting it to a heat-drying and curing process to produce a separator.

[0016] Optionally, the paste is applied to the base film to a thickness ranging from 15 μm to 75 μm.

[0017] Optionally, the binder comprises at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE).

[0018] Optionally, the method of application includes knife coating, gravure roll coating, dip coating, narrow coating or spray coating.

[0019] Optionally, the heat-dry-cure process includes drying in a forced air oven at 60°C-80°C, followed by transferring to a vacuum oven at 40°C-70°C for 12 hours or more.

[0020] On the other hand, an embodiment of the present invention further provides a pole piece capable of absorbing water and acid, the pole piece capable of absorbing water and acid comprising a pole piece base, a metal-organic framework material dispersed on a surface of the pole piece base, and the pole piece base comprising a positive pole piece and / or a negative pole piece.

[0021] On the other hand, embodiments of the present invention further provide a battery, the battery including the water and acid absorbing battery separator.

[0022] On the other hand, embodiments of the present invention further provide a battery, the battery including the water and acid absorbing pole pieces. [Effects of the Invention]

[0023] The present invention provides a battery separator (base film) coated with a metal-organic framework material having a high specific surface area and effective adsorption sites within its pores, resulting in a composite separator capable of efficiently adsorbing impurities such as water and acid. The water- and acid-absorbing battery separator effectively adsorbs impurities such as water and acid, further improving the cycle stability of the battery. The water- and acid-absorbing battery separator also reduces the strict water control requirements during battery assembly, enabling direct assembly of lithium batteries in the external environment, simplifying the assembly process and effectively reducing costs. Furthermore, the water- and acid-absorbing battery separator according to the present invention effectively inhibits lithium dendrites and extends the service life of the positive electrode material. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a photograph of a battery separator capable of absorbing water and acid prepared in Example 1 of the present invention. [Figure 2] FIG. 2 is a SEM image of the surface morphology of the battery separator capable of absorbing water and acid prepared in Example 1 of the present invention. [Figure 3] FIG. 3 is a comparison diagram of battery cycle characteristics in Example 1 of the present invention and Comparative Example 1. [Figure 4] FIG. 4 is a comparison diagram of battery cycle characteristics in Example 2 of the present invention and Comparative Example 2. [Figure 5] FIG. 5 is a comparison diagram of the battery magnification characteristics in Example 2 of the present invention and Comparative Example 2. [Figure 6] FIG. 6 is a comparative diagram of the battery cycle characteristics after treatment of the NMC622 positive electrodes in Example 3 of the present invention and Comparative Example 3 at a humidity of 30%. [Figure 7]FIG. 7 shows the battery cycle characteristics of the battery separators capable of absorbing water and acid in different ratios prepared in the examples of the present invention in a 1M LiPF / EC-DMC electrolyte with a water content of 800 ppm. [Figure 8] FIG. 8 shows the battery cycle performance of different thicknesses of water and acid absorbable battery separators in an embodiment of the present invention in a 1M LiPF6 / EC-DMC electrolyte with a water content of 800 ppm. [Figure 9] FIG. 9 is a SEM image of the surface morphology of the Li electrode and the NCM622 electrode after 200 cycles in Example 1 of the present invention and Comparative Example 1. [Figure 10] FIG. 10 is a schematic diagram of the porous structure of MIL-101(Cr) according to the present invention. [Figure 11] FIG. 11 is a comparison diagram of battery cycle characteristics in Example 4 of the present invention and Comparative Example 4. [Figure 12] FIG. 12 is a structural schematic diagram of a battery separator capable of absorbing water and acid according to an embodiment of the present invention. [Figure 13] FIG. 13 is a structural schematic diagram of another water and acid absorbing battery separator according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] As is known from the background art, trace amounts of water and acid currently present in batteries significantly affect the cycle characteristics of the battery.

[0026] Specifically, the lithium battery electrolyte is a carrier that transports ions in the battery. It is usually composed of lithium salt and organic solvent. The electrolyte plays the role of conducting ions between the positive and negative electrodes of the lithium battery, and is the guarantee that lithium-ion (metal) batteries can achieve advantages such as high voltage and high specific energy. LiPF6 has excellent balance characteristics with the currently commonly used organic carbonate ester solvents, so it exhibits relatively high lithium ion conductivity, and therefore LiPF6 remains the main conductive salt for lithium ions. Furthermore, LiPF6 electrolyte passivates the positive electrode current collector (aluminum foil), allowing the battery to maintain a voltage of 4.2V vs. Li / Li+ The layered nickel-rich cathode material allows the battery to operate at a higher potential than the conventional cathode, which is a prerequisite for achieving high energy density in the battery.

[0027] However, LiPF6 is highly sensitive to water, and the presence of trace amounts of water in the electrolyte causes a series of side reactions. The resulting acidic substances, such as highly corrosive hydrofluoric acid (HF), accelerate the dissolution of the positive electrode transition metal (TM). The dissolved TM cations then diffuse to the surface of the negative electrode, destroying the solid electrolyte interface (SEI). This leads to a degradation of the capacity of the positive electrode material (especially nickel-rich positive electrode materials) and a deterioration of the battery's cycling characteristics. Therefore, in the entire assembly process of lithium-ion (metal) batteries, both the preparation of the electrolyte, which consists of lithium salt and organic solvent, and the drying of the positive and negative electrode active materials must be performed in an extremely low-humidity environment such as a glove box or dry room, thereby ensuring that excess water is not introduced into the battery. Such strict water control requires high costs (both in laboratories and in industries). Furthermore, industrially, LiPF6 is generally produced using anhydrous HF (which is considered a fluorination reagent and recrystallization solvent). Therefore, even with advanced processes, it is difficult to completely remove trace amounts of water and hydrogen fluoride from the electrolyte (the water content of purchased electrolytes is generally controlled to <20-30 ppm), which also leads to poor battery cycle characteristics.

[0028] To solve the above problems, an embodiment of the present invention provides a battery separator capable of absorbing water and acid, which includes a substrate and a metal-organic framework material, and the metal-organic framework material is dispersed on at least one surface of the substrate.

[0029] It should be noted that the metal-organic framework material being dispersed on at least one surface of the underlayer means that the metal-organic framework material may be attached to one or both surfaces of the underlayer along the thickness direction of the underlayer.

[0030] The undercoat layer is intended to carry a metal-organic framework material to enhance the strength of the battery separator, which can absorb water and acid, and the material of the undercoat layer can be selected from polyolefin, glass fiber, or electrospun polyimide.

[0031] In one embodiment, the metal-organic framework material has a specific surface area of ​​>900 m 2 / g, and the specific surface area is measured using the BET test method, with the test conditions being 80°C for 12 hours of degassing and then testing at 77K in a N2 atmosphere. Furthermore, in order to improve the separator's ability to adsorb moisture and acidic substances, the specific surface area must be greater than 2400m 2 / g of metal-organic framework material may be selected and used.

[0032] The metal-organic framework material has a porous structure, and the pore size of the metal-organic framework material may be in the range of 0.92 nm to 3.5 nm. The pore size of the metal-organic framework material is calculated using the Tikhonov regularization fitting method based on the specific surface area.

[0033] To improve the water and acid absorption properties of the battery separator capable of absorbing water and acid, a metal-organic framework material having a high specific surface area and containing available adsorption sites (e.g., vacant coordination sites or ionic adsorption sites) within the pores may be selected and used. In one embodiment, the metal-organic framework material may be at least one selected from HKUST-1, MOF-801, MIL-101, MOF-303, and UiO-66. To improve the adsorption properties of the battery separator capable of absorbing water and acid, in one embodiment, the metal-organic framework material may be MIL-101(Cr). MIL-101(Cr) has a higher surface area (2400 m 2 g -1 ) and unsaturated metal sites. MIL-101 has two types of pores with pore sizes of 2.14 nm and 3.4 nm, respectively.

[0034] Furthermore, the building blocks of MIL-101(Cr) have relatively high polarity, providing good adsorption sites for water and HF. By selecting and using metal-organic framework materials with high specific surface areas and effective water and acid absorption sites, the water and acid absorption properties of battery separators capable of absorbing water and acid can be effectively improved. The adsorption energies of MIL-101 for HO and HF were calculated using density functional theory (DFT) (shown in Figure 10). In Figure 10, A represents the MIL-101(Cr) crystal lattice structure, B represents two types of mesopores (spheres representing the internal available volume), C represents the MIL-101(Cr) structural unit (Cr-MBU, Cr metal-building unit), and D represents the top and side views of the water adsorption sites of Cr-MBU. As can be seen, Cr-MBU has a relatively high water adsorption site capacity. E represents the adsorption energy of Cr-MBU for HO and HF. The water adsorption energy of Cr-MBU reaches at most -95.6 kJ / mol. It shows that even when two water molecules are adsorbed, Cr-MBU still adsorbs more water with an adsorption energy of −58.7 kJ / mol.

[0035] The water- and acid-absorbing battery separator according to the embodiment of the present invention can be used in combination with an electrolyte having a water content of at most 800 ppm to assemble into a battery. On the one hand, the water- and acid-absorbing battery separator can effectively adsorb impurities such as water and acid in the electrolyte, further improving the cycle stability of the battery. On the other hand, the water- and acid-absorbing battery separator can reduce the strict water control requirements during the battery assembly process, enabling lithium batteries to be assembled directly in the external environment, simplifying the assembly process and effectively reducing costs. Furthermore, the water- and acid-absorbing battery separator according to the embodiment of the present invention can effectively inhibit lithium dendrites and extend the service life of the positive electrode material.

[0036] Referring to Figures 12 and 13, Figure 12 is a structural schematic diagram of a battery separator capable of absorbing water and acid according to an embodiment of the present invention, and Figure 13 is a structural schematic diagram of another battery separator capable of absorbing water and acid according to an embodiment of the present invention.

[0037] Referring to Figures 12 and 13, an embodiment of the present invention provides a battery separator capable of absorbing water and acid, which is a composite battery separator, comprising a separator body 1 and a metal-organic framework material layer 2, wherein the separator body 1 is made of the base film, the metal-organic framework layer 2 is made of the metal-organic framework material, and the metal-organic framework material layer 2 is attached to at least one surface of the separator body 1, the thickness of the metal-organic framework material layer 2 is in the range of 15 μm to 75 μm, and the water absorption of the battery separator capable of absorbing water and acid is less than 800 ppm.

[0038] It should be noted that the water absorption of the water and acid absorbable battery separator of the present application is 800 ppm or less, which means that after the water and acid absorbable battery separator of the present application is assembled into a battery, the battery can still be stably cycled even if the water content of the electrolyte is at most 800 ppm. The water content of commercially available electrolytes is generally controlled to <20-30 ppm. Therefore, the water and acid absorbable battery separator of the present application can effectively absorb water in the electrolyte and reduce the strict water control requirements during battery assembly. This allows batteries to be directly assembled in an external environment, simplifying the assembly process and effectively reducing costs.

[0039] The water and acid absorbing battery separator further has acid absorption properties, and the acid absorption amount of the water and acid absorbing battery separator is at most 1107 ppm. That is, after the water and acid absorbing battery separator of the present application is assembled into a battery, even if the acid content (acidic substance such as HF) in the electrolyte is at most 1107 ppm, the battery can still be stably cycled.

[0040] It should be noted that the metal-organic framework material layer being attached to at least one surface of the separator body means that the metal-organic framework material layer may be attached to one surface (shown in FIG. 12) or both surfaces (shown in FIG. 13) of the separator body along the thickness direction of the separator body.

[0041] Specifically, the thickness of the metal-organic framework material layer 2 should not be too thick or too thin. If the thickness of the metal-organic framework material layer is too thin, the water absorption properties will be poor, and if the thickness of the metal-organic framework material layer is too thick, it may affect the battery properties. Therefore, the thickness range of the metal-organic framework material layer is 15 μm to 75 μm, and specifically may be 45 μm, 50 μm, 55 μm, 60 μm, 70 μm, 80 μm, 90 μm, etc.

[0042] In order to improve the stability of the metal-organic framework material layer 2 attached to the separator body and reduce the complexity of the process, in a specific embodiment, the metal-organic framework material layer 2 may be bonded to the separator body 1 by a binder, and the binder may be at least one selected from PVDF and PTFE. In other embodiments, the metal-organic framework material layer may be attached to the separator body by other methods, such as grafting with a coupling agent or chemical crosslinking.

[0043] The separator body carries an organic frame material layer to enhance the strength of the battery separator, which can absorb water and acid, and may be any one of a polyolefin membrane, a glass fiber membrane, and an electrospun polyimide membrane.

[0044] In one embodiment, the specific surface area is greater than 900 m 2 / g, a metal-organic framework material with a specific surface area of ​​>2400 m may be selected and used. 2 / g metal-organic framework materials can be selected and used. The specific surface area is measured using the BET test method, and the test conditions are 80°C for 12 hours of degassing and then testing at 77K in a N2 atmosphere.

[0045] Those skilled in the art will readily understand that metal-organic framework materials (MOFs) have high adsorption properties due to their porous nature. In one embodiment, a metal-organic framework material with a pore size ranging from 0.92 nm to 3.5 nm may be selected and used. The pore size of the metal-organic framework material was calculated using the Tikhonov regularization fitting method based on the specific surface area.

[0046] In order to improve the water and acid absorption properties of the battery separator capable of absorbing water and acid, in a specific embodiment, the material of the metal-organic framework material layer 2 may be MIL-101. Take MIL-101(Cr) as an example, the specific surface area of ​​MIL-101(Cr) is at most 2400 m 2 / g, and such a high specific surface area allows for rapid adsorption of moisture and acidic substances, and the presence of two types of pores with different pore sizes allows for storage of large amounts of water, thereby improving the water and acid absorption properties of the battery composite separator. In another embodiment, the material of the metal-organic framework material layer may further be at least one selected from HKUST-1, MOF-801, MOF-303, and UiO-66.

[0047] In order to explain in detail the process of obtaining a battery separator capable of absorbing water and acid, an example of a manufacturing method for a battery separator capable of absorbing water and acid is provided below. It should be noted that the manufacturing method according to the present application is merely an example and should not be construed as limiting the present application.

[0048] In one example, a method for making a battery separator capable of absorbing water and acid includes: (1) mixing a metal-organic covalent material and a binder to prepare a paste; (2) pouring the paste onto a commercial polyolefin separator and knife-coating it with a blade; and (3) drying the knife-coated membrane to obtain a battery separator capable of absorbing water and acid.

[0049] The water and acid absorbing battery separator according to the embodiment of the present invention has a metal-organic framework material layer attached to the separator body. When the water and acid absorbing battery separator is assembled into a battery, the metal-organic framework material layer of the water and acid absorbing battery separator can adsorb impurities such as water and acid in the battery. The thickness of the metal-organic framework material layer is in the range of 15 μm to 75 μm, which not only ensures the adsorption effect but also prevents the separator from being too thick and affecting the battery performance, thereby improving the cycle stability of the battery. On the other hand, the water and acid absorbing battery separator can reduce the strict water control requirements during the battery assembly process, allowing the battery to be assembled directly in the external environment, simplifying the assembly process and effectively reducing costs.

[0050] In order to solve the above problems, an embodiment of the present invention provides a method for manufacturing a battery separator capable of absorbing water and acid, the method for manufacturing the battery separator capable of absorbing water and acid includes: Step (1) of preparing a paste by mixing a metal organic framework material and a binder in a molar ratio of 5:5 to 9:1; and (2) applying the paste onto an undercoat film and carrying out a heat-drying and curing process to produce the separator.

[0051] In one embodiment, the metal-organic framework material has a specific surface area of ​​>900 m 2 / g. Furthermore, to improve the adsorption rate of water and acidic substances, the specific surface area is more than 2400 m 2 / g of metal-organic framework material may be selected and used.

[0052] The metal-organic framework material may be at least one selected from HKUST-1, MOF-801, MIL-101, MOF-303, and UiO-66.

[0053] Application methods include knife coating, gravure roll coating, dip coating, narrow coating or spray coating.

[0054] The thickness of the paste applied to the base film should not be too thick or too thin. If it is too thin, the water and acid absorption effect will be poor, and if it is too thick, it will affect the battery characteristics. Therefore, in a specific embodiment, the thickness of the paste applied to the base film ranges from 15 μm to 75 μm, for example, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, and 70 μm.

[0055] The heat-dry-cure process involves drying in a forced air oven at 60°C to 80°C, then transferring to a vacuum oven and drying at 40°C to 70°C for 12 hours or more.

[0056] The metal-organic framework material has a porous structure, and the pore size range of the metal-organic framework material can be 0.92 nm to 3.5 nm. The pore size of the metal-organic framework material is calculated using the Tikhonov regularization fitting method based on the specific surface area. Taking MIL-101(Cr) as an example, MIL-101(Cr) has two types of pores, with pore sizes of 2.14 nm and 3.4 nm, respectively.

[0057] The binder includes at least one of PVDF and PTFE.

[0058] The undercoat layer is intended to carry a metal-organic framework material to enhance the strength of the battery separator, which can absorb water and acid, and the material of the undercoat layer can be selected from polyolefin, glass fiber, or electrospun polyimide.

[0059] In the present invention, a composite separator capable of efficiently adsorbing impurities such as water and acid in a battery is fabricated by coating a metal-organic framework material on the battery separator. On the one hand, the water and acid absorbing battery separator can effectively adsorb impurities such as water and acid in the battery, further improving the cycle stability of the battery. On the other hand, the water and acid absorbing battery separator can reduce the strict water control requirements during the battery assembly process, allowing lithium batteries to be directly assembled in the external environment, simplifying the assembly process and effectively reducing costs.

[0060] To solve the above problems, an embodiment of the present invention provides a water and acid absorbing pole piece, which includes a pole piece base, a metal organic framework material dispersed on the surface of the pole piece base, and the pole piece base includes a positive pole piece and / or a negative pole piece.

[0061] The specific surface area of ​​the metal-organic framework material is greater than 900m 2 / g, and the specific surface area of ​​the metal-organic framework material is >2400 m 2 / g.

[0062] The pore size range of the metal-organic framework material is 0.92 nm to 3.5 nm.

[0063] The metal-organic framework material is at least one selected from HKUST-1, MOF-801, MIL-101, MOF-303, and UiO-66. In addition, the metal-organic framework material may be MIL-101 to improve the adsorption properties of the pole pieces capable of absorbing water and acid.

[0064] To solve the above problem, an embodiment of the present invention provides a battery, which includes a battery separator capable of absorbing the water and acid.

[0065] The positive electrode material of the battery may be at least one selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, nickel-cobalt-manganese ternary material, and layered lithium-rich material.

[0066] The negative electrode material of the battery may be at least one selected from graphite, metallic lithium, silicon carbon, phosphorus carbon, silicon, and phosphorus.

[0067] The battery according to the embodiment of the present invention includes the water and acid absorbing battery separator. On the one hand, the water and acid absorbing battery separator can effectively adsorb impurities such as water and acid in the battery electrolyte, further improving the cycle stability of the battery. On the other hand, the water and acid absorbing battery separator can reduce the strict water control requirements during the battery assembly process, allowing the lithium battery to be directly assembled in the external environment, simplifying the assembly process and effectively reducing costs.

[0068] To solve the above problem, an embodiment of the present invention provides a battery, which includes a pole piece capable of absorbing the water and acid.

[0069] The battery according to the embodiment of the present invention includes the water and acid absorbing electrode pieces. On the one hand, the water and acid absorbing battery separator can effectively adsorb impurities such as water and acid in the battery, further improving the cycle stability of the battery. On the other hand, the water and acid absorbing battery separator can reduce the strict water control requirements during the battery assembly process, making it possible to assemble the lithium battery directly in the external environment, simplifying the assembly process and effectively reducing costs.

[0070] The battery according to the embodiment of the present invention includes the water and acid absorbing battery separator, and a porous metal-organic framework material layer is attached to the separator body. When the water and acid absorbing battery separator is assembled into a battery, the metal-organic framework material layer of the water and acid absorbing battery separator can adsorb impurities such as water and acid in the electrolyte. The thickness of the metal-organic framework material layer is in the range of 15 μm to 75 μm, which not only ensures the adsorption effect but also prevents the separator from being too thick and affecting the battery performance, thereby improving the cycle stability of the battery. On the other hand, the water and acid absorbing battery separator can reduce the strict water control requirements during the battery assembly process, allowing the battery to be assembled directly in the external environment, simplifying the assembly process and effectively reducing costs.

[0071] The water and acid absorbing battery separator and its manufacturing method, the water and acid absorbing pole piece, and the battery according to the present invention will be described in more detail below with reference to specific examples and comparative examples.

[0072] Example 1 Manufacturing of MIL-101(Cr) 5g of Cr(NO3)3·9H2O and 2.1g of terephthalic acid were dissolved in 50ml of deionized water, and 1mL of 40% hydrofluoric acid was added dropwise while stirring. The mixture was then ultrasonically vibrated for 30 minutes, then transferred to a 100ml reaction vessel (lined with polytetrafluoroethylene) and reacted at 220°C for 8 hours. After cooling to room temperature, the mixture was centrifuged and then washed alternately with hot N,N-dimethylformamide (DMF) and absolute ethanol multiple times. After drying in a drying box at 130°C for 12 hours, 3.1g of purified MIL-101(Cr) sample was obtained.

[0073] Manufacturing battery separators capable of absorbing water and acid (1) Paste production Mix MIL-101(Cr) and PVDF in a mass ratio of 7:3, add N-methylpyrrolidone (NMP) in a ratio of 1 g of the mixture to 2 mL of NMP, and polish evenly. (2) Pour the paste onto a commercial polyolefin separator and knife-coat it with a blade (to a coating thickness of 15 μm); (3) The membrane is transferred to a forced air oven and dried at 60°C to 80°C, and then transferred to a vacuum oven and dried at 40°C to 70°C for 12 hours or more.

[0074] The prepared water and acid absorbing battery separator is shown in Figure 1. Electron microscope scanning was performed on the water and acid absorbing battery separator in Example 1 using a Hitachi SU-3800 field emission scanning electron microscope, and the results are shown in Figure 2. As can be seen from Figure 2, the metal-organic framework material is uniformly dispersed on the surface of the water and acid absorbing battery separator.

[0075] Electrolyte production 1M LiPF6 / EC-DMC electrolyte with a water content of 800 ppm was prepared by adding 800 ppm water to 1M LiPF6 ethylene carbonate / dimethyl carbonate (EC / DMC) (3 / 7, v / v) electrolyte (commercially available electrolytes typically have a water content of <20-30 ppm).

[0076] Battery assembly process LiNi in the glove box 0.6 Mn 0.2 Co 0.2 An NCM622 / Li button cell battery was assembled using O2 (NMC) as the positive electrode, lithium metal as the negative electrode, the water and acid-absorbing battery separator from Example 1 as the battery separator, and a 1M LiPF6 / EC-DMC electrolyte with a water content of 800 ppm as the electrolyte. The positive electrode piece was 12 mm in diameter (containing 5 mg to 10 mg of active material), and the lithium metal negative electrode was 15.4 mm in diameter and 400 μm thick.

[0077] The battery cycle characteristics (positive electrode: NMC622, negative electrode: Li) were tested at 0.1C, with a charge / discharge voltage range of 2.7 to 4.3V. After two cycles, cycle tests and power consumption tests were performed at 1C (electrolyte water content: 800 ppm). The test results are shown in Figure 3.

[0078] As can be seen from FIG. 3, when the water content of the electrolyte is 800 ppm (equivalent to 40 times the water content of a normal electrolyte), the battery in Comparative Example 1 loses its capacity to 151 mAh g after 50 cycles. -1 from 84mAh g -1 and the capacity retention rate is 55%, while the battery assembled with the water and acid absorbable battery separator according to the present invention still has a capacity retention rate of 60% after 300 cycles. As can be seen from this, the water and acid absorbable battery separator according to the embodiment of the present invention can effectively adsorb water in the electrolyte, and the battery assembled with this water and acid absorbable battery separator can achieve stable cycle characteristics.

[0079] Furthermore, the surface morphologies of the Li electrode and NCM622 electrode of the batteries in Example 1 and Comparative Example 1 after 200 cycles were observed using a Zeiss field emission scanning electron microscope (ZEISS Gemini, 5 kV, Germany), and the test results are shown in FIG. 9. As can be seen from FIG. 9, after 200 cycles, there were no dendrites on the surface of the Li electrode in Example 1 (D in FIG. 9), but there were obvious dendrites on the surface of the battery in Example 1 (C in FIG. 9). Looking from the positive electrode side of the battery, it is easy to observe that there were a large number of cracks in the NMC622 particles of the battery in Comparative Example 1 (A in FIG. 9), but the water- and acid-absorbing battery separator in Example 1 can clearly suppress the cracks (B in FIG. 9).

[0080] Example 2 Acidic electrolyte production 1M LiPF6EC / DMC (3 / 7, v / v) electrolyte was mixed with 300 ppm water, placed in a forced air oven at 80°C for 21 days, and then removed to test for an acidic content of 1107 ppm (purchased electrolytes are generally controlled to have an acidic content of <20 ppm).

[0081] Battery assembly process LiNi in the glove box 0.6 Mn 0.2 Co 0.2 An NCM622 / Li battery was assembled using O2 (NMC) as the positive electrode, lithium metal as the negative electrode, the water and acid-absorbing battery separator from Example 1 as the separator, and the acidic electrolyte from Example 2 as the electrolyte. The positive electrode piece was 12 mm in diameter (containing 5 mg to 10 mg of active material), and the lithium metal negative electrode was 15.4 mm in diameter and 400 μm thick.

[0082] The battery cycle characteristics (positive electrode: NMC622, negative electrode: Li) were tested with a charge / discharge voltage range of 2.7 to 4.3 V. Cycle tests and power consumption tests were conducted at 0.5 C (the top two cycles were 0.1 C). The test results are shown in Figures 4 and 5.

[0083] As can be seen from Figure 4, when the acid content of the electrolyte is 1107 ppm (equivalent to 55 times the acid content of a typical electrolyte), the battery assembled with the commercial separator in Comparative Example 2 exhibits a larger discrepancy in charge / discharge capacity, with the discharge capacity being much lower than the charge capacity. In the top 10 cycles, the coulombic efficiency is lower than 60%, and the final coulombic efficiency is only about 90%, indicating that by-products of LiPF6 liquid electrolyte at high temperatures can significantly damage the battery. In contrast, the battery assembled with the battery separator capable of absorbing water and acid according to the present invention exhibits stable cycle characteristics over 200 cycles, with a coulombic efficiency of at most 98%.

[0084] As can be seen from FIG. 5, the battery assembled with the battery separator capable of absorbing water and acid according to the embodiment of the present invention has excellent large current charge / discharge characteristics at different charging / discharging rates, while the battery assembled with the commercial separator in the comparative example cannot be stably cycled even at 0.1C.

[0085] As can be seen from Figures 4 and 5, the battery separator capable of absorbing water and acid according to the embodiment of the present invention can effectively adsorb the acid in the electrolyte, and the battery including the battery separator capable of absorbing water and acid according to the present invention can achieve stable cycle characteristics.

[0086] Example 3 Before assembling the button battery, the NMC622 positive electrode was left in a temperature / humidity chamber (30°C, 30% relative humidity) for 1 hour, and then the battery was assembled in a dry room. After 24 hours, the charge / discharge cycle was started and the battery cycle characteristics were tested at 1C. The positive electrode was NMC622 and the negative electrode was Li. The test conditions were 2.7 to 4.3V, and the test results are shown in Figure 6.

[0087] As can be seen from Figure 6, after 200 cycles, the battery had a capacity retention rate of 75% and a discharge capacity of 120 mAhg. -1 However, the battery assembled with the commercial separator in Comparative Example 3 showed a sudden drop in performance after only 85 cycles, with a discharge capacity of 22.6 mAhg after 200 cycles. -1 The capacity retention rate is 14.7%, which indicates that the acid-absorbing battery separator according to the embodiment of the present invention can reduce the strict water control requirements during the battery assembly process, and can realize the direct assembly of lithium batteries in an external environment, thereby simplifying the assembly process and effectively reducing costs.

[0088] Example 4 The difference between Example 4 and Example 1 is the preparation of the electrolyte. 1M LiPF6 / ethylene carbonate / dimethyl carbonate (EC / DMC) (3 / 7, v / v) electrolyte was mixed with 300 ppm water to produce a 1M LiPF6 / EC-DMC electrolyte with a water content of 300 ppm (purchased electrolytes generally have a water content of <20-30 ppm). The rest of the procedure was the same as in Example 1.

[0089] The battery cycle characteristics (positive electrode: NMC622, negative electrode: Li) were tested at 0.1C, with a charge / discharge voltage range of 2.7 to 4.3V. After two cycles, a cycle test and a power consumption test were performed at 1C (electrolyte water content: 300 ppm). The test results are shown in Figure 11.

[0090] 11, when the water content of the electrolyte is 300 ppm (corresponding to 15 times the water content of a normal electrolyte), the battery assembled with the battery separator capable of absorbing water and acid according to the present invention has a capacity retention rate of 86% even after 300 cycles. Meanwhile, the battery in Comparative Example 4 has a capacity retention rate lower than 55% under the same cycle conditions.

[0091] Example 5 For the preparation of MIL-101(Cr), see Example 1.

[0092] Manufacturing battery separators capable of absorbing water and acid (1) Paste production Mix MIL-101(Cr) and PVDF in a mass ratio of 5:5, add N-methylpyrrolidone (NMP) in a ratio of 1 g of the mixture to 2 mL of NMP, and polish evenly. (2) Pour the paste onto a commercial polyolefin separator and knife-coat it with a blade (to a coating thickness of 30 μm); (3) The membrane is transferred to a forced air oven and dried at 60°C to 80°C, and then transferred to a vacuum oven and dried at 40°C to 70°C for 12 hours or more.

[0093] Electrolyte production 800 ppm of water is added to 1 M LiPF6 / EC / DMC (3 / 7, v / v) electrolyte to prepare 1 M LiPF6 / EC-DMC electrolyte with a water content of 800 ppm.

[0094] Battery assembly process The ternary material consists of a 12mm diameter NMC cathode piece (containing 5-10mg of active material), a battery separator capable of absorbing water and acid, a lithium metal anode (15.4mm diameter, 400µm thick), and a 1M LiPF6 / EC-DMC electrolyte with a water content of 800ppm.

[0095] The battery cycle characteristics (positive electrode: NMC622, negative electrode: Li) were tested, with a charge / discharge voltage range of 2.7 to 4.3 V. After two cycles at 0.1 C, a cycle test and a power consumption test were performed at 1 C (electrolyte with a water content of 800 ppm). The test results are shown in Figure 7.

[0096] Example 6 The mass ratio of MIL-101 to PVDF was changed to 9:1, and the remaining materials were mixed in the same manner as in Example 4. The cycle test and the power supply characteristic test were carried out on the battery. The test results are shown in Figure 7.

[0097] As can be seen from Figure 7, the batteries assembled with battery separators capable of absorbing water and acid in different ratios can still reach 300 cycles even when the water content is 800 ppm and the electrolyte is 1 M LiPF / EC-DMC.

[0098] Example 7 Electrolyte production 800 ppm of water is added to 1 M LiPF6 / EC / DMC (3 / 7, v / v) electrolyte to prepare 1 M LiPF6 / EC-DMC electrolyte with a water content of 800 ppm.

[0099] Battery assembly process The ternary material NMC positive electrode piece has a diameter of 12 mm (active material is 5-10 mg), the battery separator capable of absorbing water and acid in Example 1 (total thickness is 40 μm, coating thickness is 15 μm), lithium metal negative electrode (diameter 15.4 mm, thickness 400 μm), and 1 M LiPF6 / EC-DMC electrolyte with a water content of 800 ppm.

[0100] The battery cycle characteristics (positive electrode: NMC622, negative electrode: Li) were tested, with a charge / discharge voltage range of 2.7 to 4.3 V. After two cycles at 0.1 C, a cycle test and a power consumption test were performed at 1 C (800 ppm aqueous electrolyte). The test results are shown in Figure 8.

[0101] Example 8 Using a 100 μm thick water and acid absorbing battery separator (total thickness 100 μm, coating thickness 75 μm), the battery was subjected to cycle tests and power rating tests in the same manner as in Example 6. The test results are shown in FIG.

[0102] As can be seen from Figure 8, the batteries assembled with water and acid absorbable battery separators of different thicknesses can still reach 300 cycles even when using a 1 M LiPF / EC-DMC electrolyte with a water content of 800 ppm.

[0103] Comparative Example 1 The separator used is a commercially available polypropylene separator (model number Celgard2500, thickness 25 μm). Battery assembly process The NMC electrode piece had a diameter of 12 mm (active material content: 5-10 mg), a commercial polypropylene separator, a lithium metal anode (diameter: 15.4 mm, thickness: 400 μm), and the electrolyte described in Example 1. The battery cycle characteristics (positive electrode: NMC622, negative electrode: Li) were tested in a 1 M LiPF / EC-DMC electrolyte with a water content of 800 ppm using the commercial polypropylene separator, with a charge / discharge voltage range of 2.7-4.3 V. The test results are shown in Figure 3.

[0104] Comparative Example 2 The separator used is a commercially available polypropylene separator (model number Celgard2500, thickness 25 μm). Battery assembly process The NMC electrode pieces had a diameter of 12 mm (5-10 mg of active material), a commercial polypropylene separator, a lithium metal anode (15.4 mm diameter, 400 μm thick), and the acidic electrolyte of Example 3. The battery's cycle and charging characteristics in the acidic electrolyte (NMC622 cathode and Li anode) were tested, with a charge / discharge voltage range of 2.7-4.3 V. The test results are shown in Figures 4 and 5.

[0105] Comparative Example 3 The separator used was a commercial polypropylene separator (model number Celgard2500, thickness 25 μm), and the rest was the same as in Example 3. The test results are shown in FIG.

[0106] Comparative Example 4 The separator used was a commercial polypropylene separator (model number Celgard2500, thickness 25 μm), and the rest was the same as in Example 4. The test results are shown in FIG.

[0107] The technical features of the embodiments described above may be combined in any manner, and for the sake of brevity, not all possible combinations of the technical features of the embodiments described above are described, but unless contradictory, any combination of these technical features should be considered to be within the scope described in this specification.

[0108] The above-described examples merely illustrate some embodiments of the present invention, and although the descriptions are more specific and detailed, they should not be understood as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the invention patent should be governed by the appended claims.

[0109] 1. A composite separator for a battery, comprising: A composite separator for a battery, comprising a separator body and a metal-organic framework material layer, the metal-organic framework material layer being attached to at least one surface of the separator body, the thickness of the metal-organic framework material layer being in the range of 15 μm to 75 μm, and the water absorption of the composite separator for the battery being 800 ppm or less.

[0110] 2. The composite separator for a battery according to claim 1, wherein the metal-organic framework material layer is adhered to the separator body.

[0111] 3. The specific surface area of ​​the metal-organic framework material layer is 900 m 2 2. The composite separator for a battery according to claim 1, wherein the composite separator has a molecular weight of 1 / g or more.

[0112] 4. The specific surface area of ​​the metal-organic framework material layer is 2400 m 2 4. The composite separator for a battery according to claim 3, wherein the composite separator has a molecular weight of 1 / g or more.

[0113] 5. The composite separator for a battery according to claim 3, wherein the metal-organic framework material layer has a porous structure with pores having a diameter ranging from 0.92 nm to 3.5 nm.

[0114] 6. The composite separator for a battery according to claim 1, wherein the material of the metal-organic framework material layer is at least one selected from the group consisting of HKUST-1, MOF-801, MIL-101, MOF-303, and UiO-66.

[0115] 7. The composite separator for a battery according to any one of claims 1 to 6, wherein the separator body is one of a polyolefin film, a glass fiber film, and an electrospun polyimide film.

[0116] 8. The composite separator for a battery according to any one of claims 1 to 6, characterized in that the composite separator for the battery has an acid absorption of 1107 ppm or less.

[0117] 9. A battery comprising the composite separator of any one of claims 1 to 8. Although the above discloses the embodiments of the present invention, the present invention is not limited thereto. Those skilled in the art can make various changes and modifications within the spirit and scope of the present invention, and therefore the scope of protection of the present invention should be limited to the scope defined by the claims. [Explanation of symbols]

[0118] 1 Separator body 2. Metal-organic frame material layer

Claims

1. A battery separator capable of absorbing water and acid, A battery separator capable of absorbing water and acid, comprising a substrate and a metal organic framework material, said metal organic framework material being dispersed on at least one surface of said substrate.

2. The metal-organic framework material has a specific surface area of ​​>900 m ２ 2. The water and acid absorbing battery separator of claim 1, wherein the water and acid absorbing capacity is 0.15 wt.

3. The metal-organic framework material has a specific surface area of ​​>2400 m ２ 3. The water and acid absorbing battery separator of claim 2, wherein the water and acid absorbing capacity is 100%.

4. 3. The battery separator capable of absorbing water and acid according to claim 2, wherein the pore size range of the metal-organic framework material is 0.92 nm to 3.5 nm.

5. 5. The battery separator capable of absorbing water and acid according to claim 1, comprising a separator body and a metal-organic framework material layer, wherein the separator body is made of the undercoat film, the metal-organic framework material layer is made of the metal-organic framework material, the metal-organic framework material layer is attached to at least one surface of the separator body, and the thickness of the metal-organic framework material layer is in the range of 15 μm to 75 μm.

6. 6. The water and acid absorbing battery separator according to claim 5, wherein the water absorption of the water and acid absorbing battery separator is 800 ppm or less.

7. 6. The water and acid absorbing battery separator of claim 5, wherein said metal organic framework material layer is adhered to said separator body.

8. 6. The battery separator capable of absorbing water and acid according to claim 5, wherein the battery composite separator has an acid absorption amount of 1107 ppm or less.

9. 6. The battery separator capable of absorbing water and acid according to claim 5, wherein the metal-organic framework material layer has a porous structure.

10. The battery separator capable of absorbing water and acid according to any one of claims 1 to 4, characterized in that the metal-organic framework material is at least one selected from HKUST-1, MOF-801, MIL-101, MOF-303, and UiO-66.

11. 5. The battery separator capable of absorbing water and acid according to claim 1, wherein the material of the base film is selected from the group consisting of polyolefin, glass fiber, and polyimide.

12. A method for producing a battery separator capable of absorbing water and acid according to any one of claims 1 to 11, comprising: Step (1) of preparing a paste by mixing a metal-organic framework material and a binder in a mass ratio of 5:5 to 9:1; and (2) applying the paste onto a base film and subjecting it to a heating, drying, and curing treatment to produce a separator.

13. 13. The method for manufacturing a battery separator capable of absorbing water and acid according to claim 12, wherein the paste is applied to the base film to a thickness ranging from 15 μm to 75 μm.

14. 13. The method of claim 12, wherein the binder comprises at least one of polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

15. 13. The method for manufacturing a battery separator capable of absorbing water and acid as claimed in claim 12, wherein the coating method includes knife coating, gravure roll coating, dip coating, narrow coating or spray coating.

16. The method for manufacturing a battery separator capable of absorbing water and acid according to any one of claims 12 to 15, wherein the heat-dry-hardening treatment includes drying in a forced air oven at a temperature of 60°C to 80°C, and then transferring to a vacuum oven and drying at a temperature of 40°C to 70°C for 12 hours or more.

17. A pole piece capable of absorbing water and acid, A water and acid absorbing pole piece comprising a pole piece base, a metal organic framework material dispersed on a surface of said pole piece base, said pole piece base comprising a positive pole piece and / or a negative pole piece.

18. A battery, A battery comprising the battery separator capable of absorbing water and acid according to any one of claims 1 to 11.

19. A battery, A battery comprising the water and acid absorbing pole piece of claim 17.

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