WO2024000580A1 - 隔离膜、二次电池、电池模块、电池包及用电装置 - Google Patents

隔离膜、二次电池、电池模块、电池包及用电装置 Download PDF

Info

Publication number
WO2024000580A1
WO2024000580A1 PCT/CN2022/103386 CN2022103386W WO2024000580A1 WO 2024000580 A1 WO2024000580 A1 WO 2024000580A1 CN 2022103386 W CN2022103386 W CN 2022103386W WO 2024000580 A1 WO2024000580 A1 WO 2024000580A1
Authority
WO
WIPO (PCT)
Prior art keywords
dielectric constant
relative dielectric
high relative
base film
constant material
Prior art date
Application number
PCT/CN2022/103386
Other languages
English (en)
French (fr)
Inventor
白文龙
吴益扬
游兴艳
武宝珍
王育文
郑蔚
叶永煌
吴凯
Original Assignee
宁德时代新能源科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to PCT/CN2022/103386 priority Critical patent/WO2024000580A1/zh
Publication of WO2024000580A1 publication Critical patent/WO2024000580A1/zh

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of battery technology, and in particular to an isolation film, a secondary battery, a battery module, a battery pack and an electrical device.
  • Lithium-ion batteries have the characteristics of high energy density, fast charging and discharging, high charging efficiency, large output power, excellent cycle and storage performance, and no memory effect. They have become the most mainstream secondary batteries currently.
  • the isolation film is one of the key inner components.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play the role of isolation.
  • the performance of the isolation film determines the interface structure, internal resistance, etc. of the battery, which directly affects the capacity, cycle, and safety performance of the battery.
  • An isolation film with excellent performance plays an important role in improving the overall performance of the battery.
  • isolation films that can be used in lithium-ion batteries are usually polymer isolation films such as polypropylene.
  • polymer isolation films such as polypropylene.
  • some polymers are coated on the surface of the isolation film to increase the viscosity.
  • These increased Polymers will have a negative effect on the rapid migration of lithium ions, that is, reducing the number of pores in the isolation membrane through which lithium ions can pass.
  • the migration rate is slower.
  • the radius of the polyanion or anion is smaller.
  • the migration rate of the anion will be greater than that of the solvated lithium ion.
  • Lithium ions so more anions will reach the negative extreme, causing relatively large concentration polarization. Therefore, regulating the isolation membrane and reducing the number of solvent molecules in the outer layer of solvated lithium ions will help increase the number and rate of solvated lithium ions, increase the migration number of lithium ions at the negative end, and thereby reduce concentration polarization. , improve the fast charging performance of the battery.
  • the present application provides a separation film and a preparation method thereof, a secondary battery, a battery module including the secondary battery, a battery pack including the battery module, and a secondary battery including the secondary battery. , battery module or battery pack power consumption device.
  • a first aspect of the present application provides a separator film for secondary batteries, which includes a base film and high relative dielectric constant material particles covalently grafted on one or both sides of the base film, the high relative dielectric constant being The relative dielectric constant of constant material particles is 50 to 150.
  • the high relative dielectric constant material is selected from: barium titanate (BaTiO3), lead titanate ( PbTiO3 ), lithium niobate ( LiNbO3 ), lead zirconate titanate (Pb(Zr 1- x Ti x O 3 )), one or more of lead metaniobate (PbNb 2 O 6 ), polyvinylidene fluoride, and copper phthalocyanine oligomer.
  • the high relative dielectric constant material particles have a particle size expressed as Dv50 of 50 nm-150 nm.
  • a chemical structure represented by formula (1) or (2) exists between the high relative dielectric constant material particles and the base film.
  • the separator film for secondary batteries wherein the material of the base film is polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene , one of polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-propylene copolymer, polyamide, polyacrylonitrile, viscose fiber, and silk fiber
  • the material of the base film is polyethylene, polypropylene, or polypropylene/polyethylene/polypropylene composite material.
  • the separator film for secondary batteries wherein the base film has a thickness of 6 to 16 ⁇ m.
  • the grafting density of the high relative dielectric constant material particles is 0.005-0.05g/cm 2 .
  • the separator film for secondary batteries has a thickness of 6 to 16 ⁇ m.
  • a second aspect of the present application provides a method for preparing a separator film for a secondary battery, the method comprising the following steps:
  • Step 1 Modify the base film and the high relative dielectric constant material particles respectively, so that the base film and the high relative dielectric constant material particles respectively carry reactive groups; the relative relative permittivity of the high relative dielectric constant material particles The dielectric constant is 50 ⁇ 150;
  • Step 2 Make a chemical reaction occur between the reactive groups carried by the base film and the reactive groups carried by the high relative dielectric constant material particles, thereby combining the high relative dielectric constant material particles with each other.
  • the valency is grafted onto one or both sides of the base film.
  • the reactive group carried by the base film is amino
  • the reactive group carried by the high relative dielectric constant material particles is epoxy. group
  • step 1 modifying the base film includes the following steps:
  • Step (1) Use a hydroxylating reagent to modify the basement membrane to obtain a basement membrane with hydroxyl groups; the modification is performed in a buffer with a pH of 7.5-9.5;
  • Step (2) chemically react a silane reagent with an amino group and the base film with a hydroxyl group to obtain a base film with an amino group;
  • the hydroxylating reagent is selected from dopamine and 4-hydroxyacetanilide;
  • the silane reagent with an amino group is ⁇ -aminopropyltriethoxysilane.
  • modifying the high relative dielectric constant material particles includes the following steps: reacting the high relative dielectric constant material particles with a coupling agent having an epoxy group, To obtain high relative dielectric constant material particles with epoxy groups;
  • the coupling agent with an epoxy group is a siloxane with an epoxy group
  • the coupling agent with an epoxy group is ⁇ -glycidoxypropyltrimethoxysilane.
  • the addition amount of the high relative dielectric constant material particles is 0.5% by weight (wt) to 10% by weight (wt).
  • a third aspect of the present application provides a secondary battery including the separator film of the first aspect of the present application.
  • a fourth aspect of the present application provides a battery module including the secondary battery of the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack, including the battery module of the fourth aspect of the present application.
  • a sixth aspect of the present application provides an electrical device, including a secondary battery selected from the third aspect of the present application, a battery module of the fourth aspect of the present application, or a battery pack of the fifth aspect of the present application.
  • the isolation film provided by the present invention can make the high relative dielectric constant material evenly distributed on the surface of the isolation film, fully exert its desolvation effect at the end of the isolation film, and improve the lithium migration number and fast charging performance.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • Figure 7 is a scanning electron microscope and energy spectrum (SEM and EDS) image of the BTO@PP isolation film prepared in Example 1.
  • Figure 8 is the infrared spectrum of the BTO@PP isolation film prepared in Example 1 (compared with the PP film).
  • Figure 9 shows the lithium migration number test results of the isolation film and PP isolation film of Example 1.
  • Figure 10 shows a comparison of the fast charging performance of the secondary batteries prepared in Example 1 and Comparative Example 8.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 ⁇ 4 and 2 ⁇ 5.
  • the numerical range “a ⁇ b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0 ⁇ 5" means that all real numbers between "0 ⁇ 5" have been listed in this article, and "0 ⁇ 5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • isolation membranes are non-polar materials. Since the electrolyte solvent needs to dissociate lithium salts, its polarity is relatively high, and there will be a problem of insufficient infiltration of the isolation membrane. In this case, the amount of electrolyte needs to be increased. , which can easily lead to an increase in cost and the production of gas in the electrolyte.
  • the migration number of lithium ions is very important and will determine the number of embedded lithium charges reaching the negative terminal.
  • the isolation membrane fiber the voids are large and the solvent When lithium ions pass through the isolation membrane, the solvation outer layer is not affected, so the lithium migration number reaching the negative electrode side is low. Therefore, it is necessary to add a desolvation group at the end of the isolation membrane to increase the lithium migration number.
  • this application provides an isolation film for secondary batteries, a method for preparing an isolation film for secondary batteries, a secondary battery including the isolation film, a battery pack including the secondary battery, including The battery module of the battery pack, and the electrical device including the secondary battery, battery module or battery pack.
  • a first aspect of the present application provides a separator film for a secondary battery, which includes a base film and high relative dielectric constant material particles covalently grafted on one or both sides of the base film.
  • Dielectric Constant The relative dielectric constant of the material particles is 50-150 (eg 50-70, 70-100, 100-120 or 120-150). The relative dielectric constant may affect the lithium migration number and battery capacity retention performance.
  • the relative dielectric constant of a material refers to the dielectric constant at room temperature (25 ⁇ 5°C), which has a well-known meaning in the art and can be tested using instruments and methods known in the art.
  • C represents the capacitance, in Farad (F);
  • d represents the sample thickness, in cm;
  • A represents the sample area, in cm 2 ;
  • the test conditions can be 1KHz, 1.0V, 25 ⁇ 5°C.
  • the relative dielectric constant of the dielectric material particles and the electrolyte can be measured by a relative dielectric constant tester.
  • a relative dielectric constant tester for details, please refer to GB/T5594.4-1985.
  • the instrument can be ZJD from Beijing AVIC Times Instrument Equipment Co., Ltd. -C relative dielectric constant tester.
  • test standard can be based on GB/T 11297.11-2015.
  • test standard can be based on GB/T 11297.11-2015.
  • Chinese patent application CN114217139A please refer to Chinese patent application CN114217139A.
  • the high relative dielectric constant material is selected from barium titanate (BaTiO 3 ), lead titanate (PbTiO 3 ), lithium niobate (LiNbO 3 ), lead zirconate titanate (Pb(Zr 1- x Ti _ _ _ _
  • the constant material can be grafted onto the base film through a chemical reaction (such as amino-epoxy reaction) to prevent the high relative dielectric constant material from falling off the isolation film end.
  • the particle size of the high relative dielectric constant material particles expressed as Dv50 is 50nm-150nm (eg, 50nm-80nm, 80nm-100nm, 100nm-120nm or 120nm-150nm).
  • the size of the high relative permittivity material particles may have an impact on the lithium migration number, the battery's capacity retention performance, and/or the battery's energy density.
  • a chemical structure represented by formula (1) or (2) exists between the high relative dielectric constant material particles and the base film.
  • the high relative dielectric constant material particles can be grafted onto the base film through an amino-epoxy reaction to form the chemical structure represented by the formula (1) or (2).
  • the base film used in the release film of the present invention may be a commercial polymer release film.
  • the material of the base film is polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene
  • ethylene copolymer vinylidene fluoride-hexafluoropropylene copolymer
  • tetrafluoroethylene-propylene copolymer polyamide, polyacrylonitrile, viscose fiber, and silk fiber.
  • the material of the base film is polyethylene (PE), polypropylene (PP), or polypropylene/polyethylene/polypropylene (PP/PE/PP) composite material. Therefore, the base film It can be commercial PE isolation film, PP isolation film or PP/PE/PP composite isolation film.
  • the base film may be a single-layer film or a multi-layer composite film, and is not particularly limited.
  • the materials of each layer can be the same or different and are not particularly limited.
  • the base film of the isolation film of the present invention may have a conventional thickness.
  • the base film used for the isolation film of the present invention may have a thickness of 6 ⁇ m to 16 ⁇ m (eg, 6 ⁇ m to 8 ⁇ m, 8 ⁇ m to 10 ⁇ m, 10 ⁇ m to 12 ⁇ m, 12 ⁇ m to 14 ⁇ m, or 14 ⁇ m to 16 ⁇ m).
  • the grafting density is used to measure how much high relative dielectric constant material is modified on the isolation film.
  • the grafting density refers to the mass of the high relative dielectric constant material per unit area of the isolation film, that is, the ratio of the mass of the high relative dielectric constant material to the area of the isolation film.
  • the grafting density is 0.005g/cm 2 -0.05g/cm 2 (for example, 0.005g/cm 2 -0.01g/cm 2 , 0.01g/cm 2 -0.02g/cm 2 , 0.02 g/cm 2 -0.03g/cm 2 , 0.03g/cm 2 -0.04g/cm 2 or 0.04g/cm 2 -0.05g/cm 2 ).
  • the grafting density of high relative dielectric constant materials may have an impact on the lithium migration number and battery capacity retention performance.
  • the graft density can be measured by thermogravimetric analysis, that is, the isolation film is heated to a certain temperature (for example, 500°C). After heating, the weight of the isolation film decreases.
  • the graft density can be obtained by calculating the proportion of the weight reduction of the isolation film. .
  • the thickness of the isolation film grafted with high relative dielectric constant material particles can be close to the thickness of the base film, ranging from 6 ⁇ m to 16 ⁇ m (for example, 6 ⁇ m to 8 ⁇ m, 8 ⁇ m to 10 ⁇ m, 10 ⁇ m to 12 ⁇ m, 12 ⁇ m to 14 ⁇ m, or 14 ⁇ m-16 ⁇ m).
  • a second aspect of the present application provides a method of preparing a separator film for a secondary battery, the method comprising the following steps:
  • Step 1 Modify the base film and the high relative dielectric constant material particles respectively, so that the base film and the high relative dielectric constant material particles respectively carry reactive groups; the relative relative permittivity of the high relative dielectric constant material particles
  • the dielectric constant is 50-150 (such as 50-70, 70-100, 100-120 or 120-150);
  • Step 2 Make a chemical reaction occur between the reactive groups carried by the base film and the reactive groups carried by the high relative dielectric constant material particles, thereby combining the high relative dielectric constant material particles with each other.
  • the valency is grafted onto one or both sides of the base film.
  • the reactive group carried by the base film is an amino group
  • the reactive group carried by the high relative dielectric constant material particles is an epoxy group.
  • An amino-epoxy reaction can occur to graft the high relative dielectric constant material particles to the base film.
  • modifying the base film includes the following steps:
  • Step (1) Use a hydroxylating reagent to modify the base membrane to obtain a base membrane with hydroxyl groups; the modification is performed in a buffer with a pH of 7.5-9.5 (for example, 8, 8.5 or 9);
  • Step (2) Chemically react a silane reagent with an amino group and the base film with a hydroxyl group to obtain a base film with an amino group.
  • the hydroxylating agent is selected from dopamine, 4-hydroxyacetanilide.
  • the amino-bearing silane reagent is ⁇ -aminopropyltriethoxysilane.
  • the buffer is Tris buffer, which is commercially available.
  • the step (1) includes: dissolving the hydroxylation reagent in the buffer and mixing it with methanol or other organic solvents to obtain a co-solvent; and then immersing the base film in the co-solvent solution , react for a certain period of time (for example, 1-2 days), and then clean the obtained isolation film to obtain a base film with hydroxyl groups.
  • the step (2) includes: mixing the silane reagent with an amino group and ethanol or other organic solvents, immersing the base film with a hydroxyl group, and heating to a certain temperature (for example, 70-90°C , for example, 80°C) for a certain period of time (for example, 5-10 h); after that, the obtained isolation film is cleaned to obtain a base film with amino groups.
  • a certain temperature for example, 70-90°C , for example, 80°C
  • a certain period of time for example, 5-10 h
  • the cleaning in step (1) or step (2) involves ultrasonicating the base film in an organic solvent such as ethanol.
  • modifying the high relative dielectric constant material particles includes the following steps: reacting the high relative dielectric constant material particles with a coupling agent having an epoxy group, To obtain high relative dielectric constant material particles with epoxy groups.
  • the coupling agent with an epoxy group is a siloxane with an epoxy group.
  • the coupling agent having an epoxy group is ⁇ -glycidoxypropyltrimethoxysilane.
  • modifying the high relative dielectric constant material particles includes the following steps: dissolving the coupling agent with an epoxy group into ethanol or other organic solvents, and then adding the high relative dielectric constant material particles. Constant material particles are stirred for a certain period of time (for example, 5-10 hours), centrifuged, washed, and dried to obtain high relative dielectric constant material particles with epoxy groups.
  • step 2 includes: placing the base film with amino groups and the high relative dielectric constant material particles with epoxy groups in ethanol or other organic solvents, under heating conditions (for example, 70-90 °C, such as 80°C), causing an amino-epoxy reaction to occur between the amino groups carried by the base film and the epoxy groups carried by the high relative dielectric constant material particles, thereby converting the high relative dielectric constant material particles into Constant material particles are covalently grafted on one or both sides of the base film.
  • step 2 also includes cleaning the isolation membrane after the reaction is completed, for example, ultrasonicating the isolation membrane in an organic solvent such as ethanol.
  • the addition amount of the high relative dielectric constant material particles is 0.5% by weight (wt) to 10% by weight (wt).
  • the addition amount of high relative dielectric constant material particles will affect the grafting density, which may affect the lithium migration number and battery capacity retention performance.
  • the base film and high relative dielectric constant material particles used in the method of the invention may have the properties described in the first aspect of the application.
  • the high relative dielectric constant material is selected from: barium titanate (BaTiO 3 ), lead titanate (PbTiO 3 ), lithium niobate (LiNbO 3 ), lead zirconate titanate (Pb(Zr 1 -xTi _ _ _ _ Modify the hydroxyl group and then graft it onto the base film through the method described above.
  • Characterization methods such as infrared spectroscopy can be used to compare the absorption spectra of the isolation film before and after covalent grafting to prove whether the covalent grafting is successful.
  • the isolation film prepared by the method is the isolation film described in the first aspect of the application.
  • a secondary battery is provided.
  • a secondary battery typically includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the positive electrode sheet may include a positive electrode current collector and a positive electrode material layer provided on the positive electrode current collector and including a positive electrode active material.
  • the positive electrode material layer may be provided on one surface of the positive electrode current collector, It can also be provided on both surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon.
  • At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the cathode material layer optionally further includes a binder.
  • a binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the cathode material layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative electrode sheet may include a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector and including a negative electrode active material.
  • the negative electrode material layer may be disposed on one surface of the negative electrode current collector, It can also be provided on both surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative active material may include at least one of the following materials: graphite (such as artificial graphite, natural graphite), soft carbon, hard carbon, mesophase carbon microspheres, carbon fiber, carbon nanotubes, silicon-based materials, tin-based Materials and lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode material layer optionally further includes a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polysodium acrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode material layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode material layer includes negative electrode active material graphite, conductive agent acetylene black, and binder styrene-butadiene rubber (SBR).
  • SBR styrene-butadiene rubber
  • the negative electrode material layer optionally also includes other auxiliaries, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • auxiliaries such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is an electrolyte solution.
  • the electrolyte solution includes electrolyte salts and solvents.
  • the electrolyte salt may be selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluoroborate, lithium dioxaloborate, lithium difluorodioxalate phosphate and lithium tetrafluoroxalate phosphate.
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery of the present application may be a lithium ion battery.
  • the secondary battery of the present application can be prepared using conventional methods.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • Exemplary preparation methods include:
  • Step 1 Stack the positive electrode piece, isolation film, and negative electrode piece in order so that the isolation film is between the positive and negative electrode pieces, and then wind it to obtain the electrode assembly (bare battery core);
  • Step 2 Place the electrode assembly in the secondary battery case, dry it, inject the electrolyte, and then go through processes such as formation and exhaust to prepare a secondary battery.
  • the secondary battery of the present application may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • FIG. 1 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • this application also provides an electrical device, which includes the secondary battery, battery module or battery pack provided by this application.
  • the secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device.
  • the electric device can be selected from mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf balls). vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • FIG. 6 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • Amino functional PP isolation membrane (NH 4 -PP isolation membrane). Dissolve 5mL of ⁇ -glycidoxypropyltrimethoxysilane into 1L of ethanol solution, then add 10g of BTO nanoparticles, stir for 6 hours, centrifuge, wash and dry to obtain BTO (EP-BTO) containing epoxy functional groups. The NH 4 -PP isolation membrane and EP-BTO were reacted in 1L ethanol solution at 80°C for 8 hours, and the resulting isolation membrane was ultrasonicated in ethanol for 30 minutes to obtain a PP isolation membrane grafted with BTO (BTO@PP isolation membrane).
  • Figure 7 is a scanning electron microscope and energy spectrum (SEM and EDS) image of the BTO@PP isolation film prepared in Example 1. As can be seen from the figure, BTO is evenly distributed on the isolation film.
  • Figure 8 is the infrared spectrum of the BTO@PP isolation film prepared in Example 1 (compared with the PP film).
  • the abscissa is the wave number, and the ordinate shows the intensity of the absorption peak. It can be seen from the figure that after covalent grafting, the absorption peak of the asymmetric stretching vibration of specific functional groups such as -Si-O-Si- (1101cm -1 ), as well as -CC- and NH appear on the infrared spectrum.
  • the absorption peaks of the bond (1067cm -1 and 1609cm -1 ) can prove that BTO and PP isolation film are composited.
  • the O atoms connected to the CC bond on the BTO@PP separator have a strong ability to attract electrons and produce an induction effect, compared with the absorption peak (1020cm -1 ) of the CC bond in the PP separator, the CC of BTO@PP The position of the bond absorption peak is red-shifted.
  • the cathode active material lithium nickel cobalt manganate (NCM523, LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), the binder polyvinylidene fluoride PVDF, and the conductive agent acetylene black SP are mixed according to a weight ratio of 98:1:1, and N-methyl is added.
  • Pyrrolidone (NMP) was used as the solvent, and the slurry was stirred under vacuum until uniform.
  • the obtained slurry was coated on a 13 ⁇ m aluminum foil with a doctor blade according to an area density of 13.7 mg/ cm2 , and then dried at 140°C, cold pressed, and cut to obtain positive electrode sheets.
  • the negative electrode slurry is evenly coated on the 7 ⁇ m negative electrode current collector copper foil at a coating density of 9.7 mg/cm 2 , and then dried, cold pressed, and cut to obtain negative electrode sheets.
  • the positive electrode piece, isolation film, and negative electrode piece in order so that the isolation film is between the positive and negative electrodes for isolation, and wind them to obtain a bare cell.
  • the bare battery core is placed in the outer package, the above-mentioned electrolyte is injected and packaged to obtain a secondary battery.
  • Example 1 use barium titanate with different particle sizes or relative dielectric constants, or change the addition amount of barium titanate to prepare a BTO@PP isolation film, and prepare a secondary battery.
  • lead titanate PbTiO 3
  • lithium niobate LiNbO 3
  • Example 1 According to the method of Example 1, a 10 ⁇ m thick PP isolation film was used to prepare a BTO@PP isolation film, and a secondary battery was prepared.
  • BTO layer slurry Dissolve barium titanate, styrene-butadiene rubber (SBR), acrylate emulsion, and carboxymethyl cellulose (CMC) in deionized water, and stir under the action of a vacuum mixer until the system is uniform, to obtain Barium titanate slurry with a solid content of 40%.
  • the barium titanate content is 40% and the particle size is 100nm.
  • Example 1 use barium titanate with different particle sizes or relative dielectric constants, or change the addition amount of barium titanate to prepare a BTO@PP isolation film, and prepare a secondary battery.
  • Example 1 The commercial PP separator film used in Example 1 was used to prepare a secondary battery according to the method of Example 1.
  • the capacity retention performance of the secondary battery is evaluated by 25°C fast charge cycle life/number of turns.
  • the secondary batteries prepared in the Examples and Comparative Examples were charged at a 2C rate, discharged at a 1C rate, and subjected to continuous cycle testing in the 3%-97% SOC range until the battery capacity was less than 80% of the initial capacity. Record the number of cycles and record it as cycle performance.
  • Test method Assemble the button battery, drop electrolyte (25 ⁇ L) on the surface of the isolation film, and use the same two metal lithium sheets as the working electrode and reference electrode, combine the potentiostatic test and the AC impedance method to test the lithium migration number. Calculated as follows:
  • I 0 and I SS are the initial and steady-state currents; R 0 and R SS are the initial and steady-state interface resistances between the electrolyte and the electrode; ⁇ V is the applied polarization voltage.
  • FIG. 9 is a bar graph showing the lithium migration numbers of the isolation film and the PP isolation film of Example 1. As can be seen from the figure, with the BTO@PP isolation film (left), the lithium migration number increases significantly, from 0.55 for the PP isolation film (right) to 0.61, indicating that the desolvation performance of the BTO@PP isolation film has been improved.
  • Figure 10 shows a comparison of the fast charging performance of the secondary batteries prepared in Example 1 and Comparative Example 8. It can be seen from the figure that using BTO@PP isolation film, charging at 5C, 10%-80% SOC, and 35°C fast charging improved by 5%, showing excellent fast charging performance.
  • the reference electrode is a lithium-plated copper wire. Start charging at a 3C rate. Use a stepwise charging method to gradually reduce the rate.
  • the negative electrode potential detected by the reference electrode is 0mV.
  • the SOC range for stopping voltage and charging is 0-80% SOC, and the sum of the time spent is the charging time.
  • the secondary battery prepared in Comparative Example 2 Compared with Example 1, the secondary battery prepared in Comparative Example 2 has a lower lithium migration number, a shorter 25°C fast charge cycle life/number of cycles, and a smaller energy density.
  • the secondary battery prepared in Comparative Example 3 has The 25°C fast charge cycle life/number of cycles is less, indicating that the size of barium titanate particles will affect the lithium migration number, capacity retention performance and/or energy density.
  • the secondary battery prepared in Comparative Example 5 has a lower lithium migration number and a shorter 25°C fast charge cycle life/number of cycles; compared with Example 14, the secondary battery prepared in Comparative Example 4
  • the battery's lithium migration number, 25°C fast charge cycle life/number of turns, and energy density are all reduced to a certain extent. It shows that the addition amount of barium titanate will affect the lithium migration number, capacity retention performance and/or energy density.
  • Example 1 Compared with Example 1, the secondary batteries prepared in Comparative Examples 6 and 7 have lower lithium migration numbers and less fast charge cycle life/number of cycles at 25°C, indicating that the relative dielectric constant of barium titanate has an impact on lithium. The number of migrations and capacity retention performance have an impact.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Laminated Bodies (AREA)
  • Cell Separators (AREA)

Abstract

本申请提供了一种隔离膜、二次电池、电池模块、电池包及用电装置。特别地，本申请提供了一种二次电池用隔离膜，其包含基膜以及共价接枝于所述基膜的一面或两面的高相对介电常数材料颗粒，所述高相对介电常数材料颗粒的相对介电常数为50～150。

Description

隔离膜、二次电池、电池模块、电池包及用电装置 技术领域
本申请涉及电池技术领域，特别涉及一种隔离膜、二次电池、电池模块、电池包以及用电装置。
背景技术
锂离子电池具有能量密度大，可快速充放电、充电效率高，输出功率大，循环及存储性能优越、没有记忆效应的特点，已经成为当前最主流的二次电池。
锂离子电池的结构中，隔离膜是关键的内层组件之一。隔离膜设置在正极极片和负极极片之间，起到隔离的作用。隔离膜的性能决定了电池的界面结构、内阻等，直接影响电池的容量、循环以及安全性能等特性，性能优异的隔离膜对提高电池的综合性能具有重要的作用。
发明内容
可用于锂离子电池的商业化的隔离膜通常为聚丙烯等聚合物隔离膜，为了增加隔离膜与极片的粘结力，会在隔离膜表面涂布一些聚合物来增加粘度，这些增加的聚合物对锂离子快速的迁移会起到负向作用，即减小隔离膜中锂离子可以通过的孔径的数量。
在溶剂化的锂离子迁移过程中，由于溶剂化的锂离子分子半径较大，因此迁移速率较慢，聚阴离子或者阴离子的半径较小，在充电过程中，阴离子迁移的速率会大于溶剂化的锂离子，因此会有较多的阴离子到达负极端，造成比较大的浓差极化。因此，对于隔离膜进行调控，减小溶剂化的锂离子外层的溶剂分子数量，将有利于提升溶剂化锂离子数量和速率，在负极端增加锂离子的迁移数，从而减少浓差极化，提升电池的快充性能。
高相对介电常数材料受电场的影响，会产生反电场。发明人发现，高相对介电常数材料的正负电荷的分离使得其自身产生的反电场可以吸附溶剂化的锂离子外层的溶剂分子，增加锂离子迁移数。但是，如果将高相对介电常数材料简单地附着在隔离膜上，由于二者间无作用力，因此会使得高相对介电常数材料从隔离膜端脱落。
为了达到上述目的，本申请提供了一种隔离膜及其制备方法，一种二次电池，包含所述二次电池的电池模块，包含所述电池模块的电池包，以及包含所述二次电池、电池模块或电池包的用电装置。
本申请的第一方面提供了一种二次电池用隔离膜，其包含基膜以及共价接枝于 所述基膜的一面或两面的高相对介电常数材料颗粒，所述高相对介电常数材料颗粒的相对介电常数为50～150。
在一些实施方案中，所述高相对介电常数材料选自：钛酸钡(BaTiO3)，钛酸铅(PbTiO 3)，铌酸锂(LiNbO 3)，锆钛酸铅(Pb(Zr 1-xTi xO 3))，偏铌酸铅(PbNb 2O 6)、聚偏二氟乙烯、酞菁铜齐聚物中的一种或几种。
在一些实施方案中，所述高相对介电常数材料颗粒以Dv50表示的粒径为50nm-150nm。
在一些实施方案中，所述高相对介电常数材料颗粒与所述基膜之间存在式(1)或(2)所示的化学结构
Figure PCTCN2022103386-appb-000001
在一些实施方案中，所述的二次电池用隔离膜，其中，所述基膜的材料为聚丙烯、聚乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺、聚四氟乙烯，聚偏氟乙烯、偏氟乙烯-四氟乙烯共聚物、偏氟乙烯-六氟丙烯共聚物、四氟乙烯-丙烯共聚物、聚酰胺、聚丙烯腈、粘胶纤维、蚕丝纤维中的一种或几种；可选地，所述基膜的材料为聚乙烯、聚丙烯、或者聚丙烯/聚乙烯/聚丙烯复合材料。
在一些实施方案中，所述的二次电池用隔离膜，其中，所述基膜具有6～16μm的厚度。
在一些实施方案中，所述的二次电池用隔离膜，其中，所述高相对介电常数材料颗粒的接枝密度为0.005～0.05g/cm 2。
在一些实施方案中，所述的二次电池用隔离膜，其中，所述二次电池用隔离膜的厚度为6～16μm。
本申请的第二方面提供了一种制备二次电池用隔离膜的方法，所述方法包括以下步骤：
步骤1：分别对基膜和高相对介电常数材料颗粒进行修饰，使得所述基膜和高相对介电常数材料颗粒分别带有可反应基团；所述高相对介电常数材料颗粒的相对介电常数是50～150；
步骤2：使所述基膜带有的可反应基团与所述高相对介电常数材料颗粒带有的可反应基团之间发生化学反应，从而将所述高相对介电常数材料颗粒共价接枝于所述基膜的一面或两面。
在一些实施方案中，所述的方法，所述步骤1中，所述基膜带有的可反应基团为氨基，所述高相对介电常数材料颗粒带有的可反应基团为环氧基团。
根据权利要求9所述的方法，在一些实施方案中，所述步骤1中，对所述基膜进行修饰包括以下步骤：
步骤(1)：使用羟基化试剂对所述基膜进行修饰，以获得带有羟基的基膜；所述修饰在pH为7.5-9.5的缓冲液中进行；
步骤(2)：使带有氨基的硅烷试剂与所述带有羟基的基膜发生化学反应，以获得带有氨基的基膜；
可选地，所述羟基化试剂选自多巴胺，4-羟基乙酰苯胺；
可选地，所述带有氨基的硅烷试剂为γ-氨丙基三乙氧基硅烷。
在一些实施方案中，所述步骤1中，对所述高相对介电常数材料颗粒进行修饰包括以下步骤：使所述高相对介电常数材料颗粒与具有环氧基的偶联剂进行反应，以获得带有环氧基团的高相对介电常数材料颗粒；
可选地，所述具有环氧基的偶联剂为带有环氧基团的硅氧烷；
可选地，所述具有环氧基的偶联剂为γ-缩水甘油醚氧丙基三甲氧基硅烷。
在一些实施方案中，所述步骤2中，以基膜的重量为基准，所述高相对介电常数材料颗粒的添加量为0.5重量(wt)％～10重量(wt)％。
本申请的第三方面提供了一种二次电池，包括本申请的第一方面的隔离膜。
本申请的第四方面提供一种电池模块，包括本申请的第三方面的二次电池。
本申请的第五方面提供一种电池包，包括本申请的第四方面的电池模块。
本申请的第六方面提供一种用电装置，包括选自本申请的第三方面的二次电池、本申请的第四方面的电池模块或本申请的第五方面的电池包。
本发明提供的隔离膜，可以使得高相对介电常数材料均匀分布在隔离膜的表面，充分发挥其在隔离膜端去溶剂化的作用，可以提升锂迁移数和快充性能。
附图说明
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的电池模块的示意图。
图4是本申请一实施方式的电池包的示意图。
图5是图4所示的本申请一实施方式的电池包的分解图。
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件
图7为实施例1制得的BTO@PP隔离膜的扫描电镜与能谱(SEM与EDS)图。
图8为实施例1制得的BTO@PP隔离膜的红外谱图(与PP膜对比)。
图9显示了实施例1的隔离膜和PP隔离膜的锂迁移数测试结果。
图10显示了实施例1和对比例8制得的二次电池的快充性能对比。
具体实施方式
下面结合实施例对本申请的实施方式作进一步详细描述。以下实施例的详细描述用于示例性地说明本申请的原理，但不能用来限制本申请的范围，即本申请不限于所描述的实施例。
以下，详细说明具体公开了本申请的二次电池及其制造方法、电池模块、电池包和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60～120和80～110的范围，理解为60～110和80～120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1～3、1～4、1～5、2～3、2～4和2～5。在本申请中，除非有其他说明，数值范围“a～b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0～5”表示本文中已经全部列出了“0～5”之间的全部实数，“0～5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
隔离膜
如前文提到的，常规隔离膜为非极性材料，由于电解液溶剂需要解离锂盐，因此其极性比较高，会存在隔离膜的浸润不足的问题，此时需要增加电解液的用量，容易导致成本的增加和电解液的产气。
锂离子迁移过程中，由于锂离子带正电，溶剂分子为极性分子，因此在锂离子正电荷的吸引下，溶剂分子中的负电中心会与正电荷结合，从而产生溶剂化效应。由于在电解液中，导电体为溶剂化的锂离子和聚阴离子，因此，锂离子的迁移数很重要，会决定到达负极端的嵌锂的电荷数量，在而隔离膜纤维空隙较大，溶剂化的锂离子在通过隔离膜时，溶剂化外层不受影响，这样到达负极侧的锂迁移数较低，因此需要在隔离膜端增加去溶剂化基团，提升锂迁移数。
基于以上问题，本申请提供一种二次电池用隔离膜，一种制备二次电池用隔离膜的方法，包含所述隔离膜的种二次电池，包含所述二次电池的电池包，包含所述电池包的电池模块，以及包含所述二次电池、电池模块或电池包的用电装置。
本申请的第一方面提供了一种用于二次电池的隔离膜，其包含基膜以及共价接枝于所述基膜的一面或两面的高相对介电常数材料颗粒，所述高相对介电常数材料颗粒的相对介电常数为50-150(例如50-70、70-100、100-120或120-150)。相对介电常数的大小可能会对锂迁移数和电池的容量保持性能等产生影响。
相对介电常数的定义和测试方法：
在本申请中，材料的相对介电常数是指室温(25±5℃)下的介电常数，其具 有本领域公知的含义，可以用本领域已知的仪器及方法进行测试。例如可以将材料制备成圆形试样后，采用LCR测试仪测试电容量C并根据公式：介电常数ε＝(C×d)/(ε 0×A)计算得到。C表示电容量，单位为法拉(F)；d表示试样厚度，单位为cm；A表示试样面积，单位为cm 2；ε 0表示真空介电常数，ε 0＝8.854×10 -14F/cm。在本申请中，测试条件可以为1KHz、1.0V、25±5℃。
本申请中，介电材料颗粒和电解液的相对介电常数可以通过相对介电常数测试仪来测定，具体可参照GB/T5594.4-1985，仪器可以选择北京中航时代仪器设备有限公司的ZJD-C相对介电常数测试仪。
此外，测试标准可依据GB/T 11297.11-2015。制备试样时可参考中国专利申请CN114217139A。
在一些实施方式中，所述高相对介电常数材料选自钛酸钡(BaTiO 3)、钛酸铅(PbTiO 3)、铌酸锂(LiNbO 3)、锆钛酸铅(Pb(Zr 1-xTi xO 3)、偏铌酸铅(PbNb 2O 6)等金属氧化物以及聚偏二氟乙烯、酞菁铜齐聚物等聚合物中的一种或几种。这些高相对介电常数材料可以通过化学反应(例如氨基-环氧反应)接枝到基膜上，避免高相对介电常数材料从隔离膜端脱落。
在一些实施方式中，所述高相对介电常数材料颗粒以Dv50表示的粒径为50nm-150nm(例如50nm-80nm、80nm-100nm、100nm-120nm或120nm-150nm)。高相对介电常数材料颗粒的大小可能会对锂迁移数、电池的容量保持性能和/或电池的能量密度产生影响。
在一些实施方式中，所述高相对介电常数材料颗粒与所述基膜之间存在式(1)或(2)所示的化学结构
Figure PCTCN2022103386-appb-000002
可通过氨基-环氧反应将所述高相对介电常数材料颗粒接枝到所述基膜上，形成所述式(1)或(2)所示的化学结构。
用于本发明隔离膜的基膜可以是商业化的聚合物隔离膜。在一些实施方式中，所述基膜的材料为聚丙烯、聚乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺、聚四氟乙烯，聚偏氟乙烯、偏氟乙烯-四氟乙烯共聚物、偏氟乙烯-六氟丙烯共聚物、四氟乙烯-丙烯共聚物、聚酰胺、聚丙烯腈、粘胶纤维、蚕丝纤维中的一种或几种。在一些实施方式中，所述基膜的材料为聚乙烯(PE)、聚丙烯(PP)、或者聚丙烯/聚乙烯/聚丙烯 (PP/PE/PP)复合材料，因此，所述基膜可以是商业化的PE隔离膜、PP隔离膜或PP/PE/PP复合隔离膜。
本发明的隔离膜中，基膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在基膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
本发明隔离膜的基膜可以具有常规厚度。在一些实施方式中，用于本发明隔离膜的基膜可以具有6μm-16μm(例如6μm-8μm、8μm-10μm、10μm-12μm、12μm-14μm或14μm-16μm)的厚度。
本发明中，采用接枝密度来衡量修饰在隔离膜上的高相对介电常数材料有多少。接枝密度是指单位面积隔离膜上的高相对介电常数材料的质量，即，高相对介电常数材料的质量与隔离膜面积的比值。在一些实施方式中，所述接枝密度为0.005g/cm 2-0.05g/cm 2(例如0.005g/cm 2-0.01g/cm 2、0.01g/cm 2-0.02g/cm 2、0.02g/cm 2-0.03g/cm 2、0.03g/cm 2-0.04g/cm 2或0.04g/cm 2-0.05g/cm 2)。高相对介电常数材料的接枝密度可能会对锂迁移数和电池容量保持性能产生影响。接枝密度的测量可以采用热重分析，即，将隔离膜加热至一定温度(例如500℃)，在加热后，隔离膜重量发生减少，可通过计算隔离膜重量减少的比例来获得接枝密度。
对于接枝有高相对介电常数材料颗粒的隔离膜，由于高相对介电常数材料颗粒的粒径通常在纳米级，与基膜厚度相比较小，因此对隔离膜厚度的影响较小。在一些实施方式中，接枝有高相对介电常数材料颗粒的隔离膜的厚度可以与基膜厚度接近，为6μm-16μm(例如6μm-8μm、8μm-10μm、10μm-12μm、12μm-14μm或14μm-16μm)。
制备隔离膜的方法
本申请的第二方面提供了一种制备用于二次电池的隔离膜的方法，所述方法包括以下步骤：
步骤1：分别对基膜和高相对介电常数材料颗粒进行修饰，使得所述基膜和高相对介电常数材料颗粒分别带有可反应基团；所述高相对介电常数材料颗粒的相对介电常数是50-150(例如50-70、70-100、100-120或120-150)；
步骤2：使所述基膜带有的可反应基团与所述高相对介电常数材料颗粒带有的可反应基团之间发生化学反应，从而将所述高相对介电常数材料颗粒共价接枝于所述基膜的一面或两面。
在一些实施方式中，所述步骤1中，所述基膜带有的可反应基团为氨基，所述高相对介电常数材料颗粒带有的可反应基团为环氧基团，二者可以发生氨基-环氧反应，从而将所述高相对介电常数材料颗粒接枝到所述基膜上。
在一些实施方式中，所述步骤1中，对所述基膜进行修饰包括以下步骤：
步骤(1)：使用羟基化试剂对所述基膜进行修饰，以获得带有羟基的基膜；所述修饰在pH为7.5-9.5(例如8、8.5或9)的缓冲液中进行；
步骤(2)：使带有氨基的硅烷试剂与所述带有羟基的基膜发生化学反应，以获得带有氨基的基膜。
在一些实施方式中，所述羟基化试剂选自多巴胺，4-羟基乙酰苯胺。
在一些实施方式中，所述带有氨基的硅烷试剂为γ-氨丙基三乙氧基硅烷。
在一些实施方式中，所述缓冲液为Tris缓冲液，其可通过商业途径获得。
在一些实施方式中，所述步骤(1)包括：将所述羟基化试剂溶解在所述缓冲液中，并与甲醇或其他有机溶剂混合得到共溶剂；之后把基膜浸入所述共溶剂溶液中，反应一定时间(例如1-2天)，之后对所得隔离膜进行清洗，得到带有羟基的基膜。
在一些实施方式中，所述步骤(2)包括：将所述带有氨基的硅烷试剂与乙醇或其他有机溶剂混合，将带有羟基的基膜浸入，加热至一定温度(例如70-90℃，例如80℃)保持一定时间(例如5-10h)；之后，对所得隔离膜进行清洗，得到带有氨基的基膜。
在一些实施方案中，所述步骤(1)或步骤(2)中的清洗均为将基膜在乙醇等有机溶剂中进行超声。
在一些实施方式中，所述步骤1中，对所述高相对介电常数材料颗粒进行修饰包括以下步骤：使所述高相对介电常数材料颗粒与具有环氧基的偶联剂进行反应，以获得带有环氧基团的高相对介电常数材料颗粒。
在一些实施方式中，所述具有环氧基的偶联剂为带有环氧基团的硅氧烷。
在一些实施方式中，所述具有环氧基的偶联剂为γ-缩水甘油醚氧丙基三甲氧基硅烷。
在一些实施方式中，对所述高相对介电常数材料颗粒进行修饰包括以下步骤：将所述具有环氧基的偶联剂溶解到乙醇或其他有机溶剂中，然后加入所述高相对介电常数材料颗粒，搅拌一定时间(例如5-10h)，离心、洗涤、干燥，可得到带有环氧基团的高相对介电常数材料颗粒。
在一些实施方式中，步骤2中所述的化学反应为氨基-环氧反应。在一些实施方式中，步骤2包括：将带有氨基的基膜与带有环氧基团的高相对介电常数材料颗粒置于乙醇或其他有机溶剂中，在加热条件下(例如70-90℃，例如80℃)，使所述基膜带有的氨基与所述高相对介电常数材料颗粒带有的环氧基团之间发生氨基-环氧反应，从而将 所述高相对介电常数材料颗粒共价接枝于所述基膜的一面或两面。任选地，步骤2还包括在反应结束后对隔离膜进行清洗，例如将隔离膜在乙醇等有机溶剂中进行超声。
在一些实施方式中，所述步骤2中，以基膜的重量为基准，所述高相对介电常数材料颗粒的添加量为0.5重量(wt)％～10重量(wt)％。高相对介电常数材料颗粒的添加量会影响接枝密度，进而可能影响锂迁移数和电池容量保持性能。
在一些实施方案中，本发明的方法中使用的基膜和高相对介电常数材料颗粒可以具有本申请的第一方面所述的性质。
在一些实施方案中，所述高相对介电常数材料选自：钛酸钡(BaTiO 3)、钛酸铅(PbTiO 3)、铌酸锂(LiNbO 3)、锆钛酸铅(Pb(Zr 1-xTi xO 3)、偏铌酸铅(PbNb 2O 6)、聚偏二氟乙烯、酞菁铜齐聚物中的一种或几种。这些材料本身带有羟基或可以通过化学反应修饰上羟基，进而可以通过上文所述的方法接枝到基膜上。
可以利用红外光谱等表征手段，比较共价接枝前后隔离膜的吸收光谱来证明共价接枝是否成功。
在一些实施方案中，所述方法制备的隔离膜为本申请第一方面所述的隔离膜。
二次电池、电池模块、电池包和用电装置
另外，以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极极片]
本申请的二次电池中，正极极片可以包括正极集流体以及设置于正极集流体上且包括正极活性材料的正极材料层，所述正极材料层可设置在正极集流体的其中一个表面上，也可设置在正极集流体的两个表面上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等 的基材)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极材料层还可选地包括粘结剂。导电剂以及粘结剂的种类和含量不受具体的限制，可根据实际需求进行选择。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极材料层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
本申请的二次电池中，负极极片可包括负极集流体以及设置于负极集流体上且包括负极活性材料的负极材料层，所述负极材料层可设置在负极集流体的其中一个表面上，也可设置在负极集流体的两个表面上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：石墨(例如人造石墨、天然石墨)、软炭、硬炭、中间相碳微球、碳纤维、碳纳米管、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极材料层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极材料层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方案中，负极材料层包含负极活性材料石墨、导电剂乙炔黑和粘结剂丁苯橡胶(SBR)。
在一些实施方式中，负极材料层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
本申请的二次电池可以是锂离子电池。
可使用常规方法制备本申请的二次电池。在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。示例性的制备方法包括：
步骤1：将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极片之间，然后卷绕得到电极组件(裸电芯)；
步骤2：将电极组件置于二次电池壳体中，干燥后注入电解液，再经过化成、排气等工序制得二次电池。
在一些实施方式中，本申请的二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块或电池包。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以选自移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商 者，均为可以通过市购获得的常规产品。
实施例1
1、制备BTO接枝的隔离膜
首先将20g多巴胺溶解在的100L Tris缓冲液(pH＝8.5)，并与甲醇(体积比1：1)混合得到共溶剂。其次把商业聚丙烯(PP)隔离膜浸入共溶剂溶液中，反应24h，之后将所得的隔离膜在乙醇中超声30min，得到羟基化的PP。其次，将10mLγ-氨丙基三乙氧基硅烷滴加到1L乙醇中，将带羟基基团的PP隔离膜浸入，80℃保持6h，将所得的隔离膜在乙醇中超声30min，得到表面含有氨基官能团的PP隔离膜(NH 4-PP隔离膜)。将5mLγ-缩水甘油醚氧丙基三甲氧基硅烷溶解到1L乙醇溶液中，然后加入BTO纳米颗粒10g，搅拌6h，离心洗涤干燥，可得到含有环氧官能团的BTO(EP-BTO)。将NH 4-PP隔离膜与EP-BTO在1L乙醇溶液中80℃反应8h，将所得的隔离膜在乙醇中超声30min，得到接枝有BTO的PP隔离膜(BTO@PP隔离膜)。
图7为实施例1制得的BTO@PP隔离膜的扫描电镜与能谱(SEM与EDS)图。从图中可以看到，BTO在隔离膜上分布均匀。
图8为实施例1制得的BTO@PP隔离膜的红外谱图(与PP膜对比)，横坐标为波数，纵坐标显示了吸收峰的强度。从图中可看出，共价接枝后，红外谱图上出现了特定的官能团如-Si-O-Si-的不对称伸缩振动的吸收峰(1101cm -1)，以及-C-C-和N-H键的吸收峰(1067cm -1和1609cm -1)，可证明BTO与PP隔离膜实现了复合。同时，由于BTO@PP隔膜上，与C-C键相连的O原子吸电子能力较强，产生了诱导效应，因此相比较PP隔膜中的C-C键的吸收峰(1020cm -1)，BTO@PP的C-C键吸收峰的位置发生了红移。
2、正极极片的制备
正极活性材料镍钴锰酸锂(NCM523即LiNi 0.5Co 0.2Mn 0.3O 2)、粘结剂聚偏氟乙烯PVDF、导电剂乙炔黑SP按照重量比98：1：1进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，在真空状态下搅拌浆料至均匀。将所得的浆料按照13.7mg/cm 2的面密度用刮刀涂布在13μm的铝箔上，之后在140℃下烘干，冷压，分切后得到正极极片。
3、负极极片的制备
将负极活性物质人造石墨、导电剂乙炔黑、复合粘结剂SBR@BTO、分散剂羧甲基纤维素钠(CMC)按照重量比为97:1:1:1溶于溶剂去离子水中，搅拌混合均匀后制备成负极浆料。将负极浆料按9.7mg/cm 2的涂敷密度均匀涂覆在7μm的负极集流体铜箔上，经过烘干、冷压、分切得到负极极片。
4、电解液的制备
在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将有机溶剂碳酸乙烯酯(EC)/碳酸甲乙酯(EMC)按照体积比3/7混合均匀，加入12.5重量％(基于碳酸乙烯酯/碳酸甲乙酯溶剂的重量计)LiPF 6溶解于上述有机溶剂中，搅拌均匀，得到电解液。
5、二次电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到裸电芯。将裸电芯置于外包装中，注入上述电解液并封装，得到二次电池。
实施例2-11
按照实施例1的方法，采用不同粒径或相对介电常数的钛酸钡、或改变钛酸钡的添加量制备BTO@PP隔离膜，并制备二次电池。
实施例12-13
按照实施例1的方法，采用钛酸铅(PbTiO 3)或铌酸锂(LiNbO 3)替代钛酸钡，制备BTO@PP隔离膜，并制备二次电池。
实施例14
按照实施例1的方法，采用10μm厚的PP隔离膜制备BTO@PP隔离膜，并制备二次电池。
对比例1
1、制备涂覆有BTO的隔离膜(BTO-coating PP)
BTO层浆料的制备：将钛酸钡、丁苯橡胶(SBR)、丙烯酸酯乳液、羧甲基纤维素(CMC)溶于去离子水中，在真空搅拌机作用下搅拌至体系呈均一状，得到固含量为40％的钛酸钡浆料。其中钛酸钡含量40％，粒径100nm。
选择聚丙烯膜作为隔离膜，将上述BTO层浆料涂覆在聚丙烯基膜上，厚度4μm，烘干，再将PVDF乳液喷涂在BTO层的上面，另一侧用相同的方法处理，烘干后使用前根据正极极片和负极极片的尺寸经分切得到合适的尺寸。
2、按照实施例1的方法制备二次电池。
对比例2-7
按照实施例1的方法，采用不同粒径或相对介电常数的钛酸钡、或改变钛酸钡的添加量制备BTO@PP隔离膜，并制备二次电池。
对比例8
采用实施例1使用的商业PP隔离膜，按照实施例1的方法制备二次电池。
二次电池的容量保持性能测试
在本申请中，通过25℃快充循环寿命/圈数来评估二次电池的容量保持性能。在25℃下，将实施例和对比例制备的二次电池以2C倍率充电，以1C倍率放电，进行3％-97％SOC区间的连续循环测试，直至电池的容量小于初始容量的80％，记录循环圈数，记为循环性能。
锂迁移数计算
测试方法：组装纽扣电池，隔离膜表面滴加电解液(25μL)，且以相同的两个金属锂片作为工作电极与参比电极，结合恒电位测试与交流阻抗法，测试锂迁移数。计算公式如下：
Figure PCTCN2022103386-appb-000003
I 0和I SS为初始电流和稳态电流；R 0和R SS为电解液和电极之间的初始和稳态界面电阻；ΔV为施加的极化电压。
图9为实施例1的隔离膜和PP隔离膜的锂迁移数的柱状图。从图中可以看出，采用BTO@PP隔离膜(左)，锂迁移数显著提升，从PP隔离膜(右)的0.55提升到0.61，说明BTO@PP隔离膜的脱溶剂化性能得到提升。
图10显示了实施例1和对比例8制得的二次电池的快充性能对比。由图中可以看出，采用BTO@PP隔离膜，以5C起充，10％-80％SOC，35℃快充改善5％，显示出优异的快充性能。
快充性能测试方法：
将正负极极片组装成叠片三电极，参比电极为电镀锂的铜丝，以3C倍率起充，采用阶梯充电的方式逐渐降低倍率，以参比电极检测到的负极电位为0mV为中止电压，充电的SOC区间为0-80％SOC，其所用时间之和为充电时间。
表1各实施例和对比例采用的钛酸钡和隔离膜的参数，以及电池性能测试结果
Figure PCTCN2022103386-appb-000004
Figure PCTCN2022103386-appb-000005
相比于对比例1，实施例1制得的二次电池的锂迁移数、25℃快充循环寿命/圈数和能量密度都得到明显提升，说明采用接枝方式在隔离膜上引入BTO比采用涂覆方式取得了更好的效果。
相比于实施例1，对比例2制得的二次电池的锂迁移数较低、25℃快充循环寿命/圈数较少，而且能量密度较小，对比例3制得的二次电池的25℃快充循环寿命/圈数较少，说明钛酸钡颗粒的大小会对锂迁移数、容量保持性能和/或能量密度产生影响。
相比于实施例1，对比例5制得的二次电池的锂迁移数较低，而且25℃快充循环寿命/圈数较少；相对于实施例14，对比例4制得的二次电池的锂迁移数、25℃快充循环寿命/圈数、能量密度都在一定程度上降低。说明钛酸钡的添加量会对锂迁移数、容量保持性能和/或能量密度产生影响。
相比于实施例1，对比例6、7制得的二次电池的锂迁移数较低，而且25℃快充循环寿命/圈数较少，说明钛酸钡的相对介电常数会对锂迁移数和容量保持性能产生影响。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加 本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (17)

  1. 一种二次电池用隔离膜，其包含基膜以及共价接枝于所述基膜的一面或两面的高相对介电常数材料颗粒，所述高相对介电常数材料颗粒的相对介电常数为50～150。
  2. 根据权利要求1所述的二次电池用隔离膜，其中，所述高相对介电常数材料选自：钛酸钡(BaTiO 3)，钛酸铅(PbTiO 3)，铌酸锂(LiNbO 3)，锆钛酸铅(Pb(Zr 1- xTi xO 3)，偏铌酸铅(PbNb 2O 6)、聚偏二氟乙烯、酞菁铜齐聚物中的一种或几种。
  3. 根据权利要求1或2所述的二次电池用隔离膜，其中，所述高相对介电常数材料颗粒以Dv50表示的粒径为50nm～150nm。
  4. 根据权利要求1-3中任一项所述的二次电池用隔离膜，其中，所述高相对介电常数材料颗粒与所述基膜之间存在式(1)或(2)所示的化学结构
    Figure PCTCN2022103386-appb-100001
  5. 根据权利要求1-4中任一项所述的二次电池用隔离膜，其中，所述基膜的材料为聚丙烯、聚乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺、聚四氟乙烯，聚偏氟乙烯、偏氟乙烯-四氟乙烯共聚物、偏氟乙烯-六氟丙烯共聚物、四氟乙烯-丙烯共聚物、聚酰胺、聚丙烯腈、粘胶纤维、蚕丝纤维中的一种或几种；可选地，所述基膜的材料为聚乙烯、聚丙烯、或者聚丙烯/聚乙烯/聚丙烯复合材料。
  6. 根据权利要求1-5中任一项所述的二次电池用隔离膜，其中，所述基膜具有6～16μm的厚度。
  7. 根据权利要求1-6中任一项所述的二次电池用隔离膜，其中，所述高相对介电常数材料颗粒的接枝密度为0.005～0.05g/cm 2。
  8. 根据权利要求1-7中任一项所述的二次电池用隔离膜，其中，所述二次电池用隔离膜的厚度为6～16μm。
  9. 一种制备二次电池用隔离膜的方法，所述方法包括以下步骤：
    步骤1：分别对基膜和高相对介电常数材料颗粒进行修饰，使得所述基膜和高相对介电常数材料颗粒分别带有可反应基团；所述高相对介电常数材料的相对介电常数是50～150；
    步骤2：使所述基膜带有的可反应基团与所述高相对介电常数材料颗粒带有的可反应基团之间发生化学反应，从而将所述高相对介电常数材料颗粒共价接枝于所述基膜的一 面或两面。
  10. 根据权利要求9所述的方法，所述步骤1中，所述基膜带有的可反应基团为氨基，所述高相对介电常数材料颗粒带有的可反应基团为环氧基团。
  11. 根据权利要求9所述的方法，所述步骤1中，对所述基膜进行修饰包括以下步骤：
    步骤(1)：使用羟基化试剂对所述基膜进行修饰，以获得带有羟基的基膜；所述修饰在pH为7.5-9.5的缓冲液中进行；
    步骤(2)：使带有氨基的硅烷试剂与所述带有羟基的基膜发生化学反应，以获得带有氨基的基膜；
    可选地，所述羟基化试剂选自多巴胺，4-羟基乙酰苯胺；
    可选地，所述带有氨基的硅烷试剂为γ-氨丙基三乙氧基硅烷。
  12. 根据权利要求9所述的方法，所述步骤1中，对所述高相对介电常数材料颗粒进行修饰包括以下步骤：使所述高相对介电常数材料颗粒与具有环氧基的偶联剂进行反应，以获得带有环氧基团的高相对介电常数材料颗粒，
    可选地，所述具有环氧基的偶联剂为带有环氧基团的硅氧烷；
    可选地，所述环氧发生剂为γ-缩水甘油醚氧丙基三甲氧基硅烷。
  13. 根据权利要求9所述的方法，所述步骤2中，以基膜的重量为基准，所述高相对介电常数材料颗粒的添加量为0.5重量(wt)％～10重量(wt)％。
  14. 一种二次电池，包括权利要求1-8中任一项所述的二次电池用隔离膜。
  15. 一种电池模块，包括权利要求14所述的二次电池。
  16. 一种电池包，包括权利要求15所述的电池模块。
  17. 一种用电装置，包括权利要求14所述的二次电池、权利要求15所述的电池模块或权利要求16所述的电池包。
PCT/CN2022/103386 2022-07-01 2022-07-01 隔离膜、二次电池、电池模块、电池包及用电装置 WO2024000580A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/103386 WO2024000580A1 (zh) 2022-07-01 2022-07-01 隔离膜、二次电池、电池模块、电池包及用电装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/103386 WO2024000580A1 (zh) 2022-07-01 2022-07-01 隔离膜、二次电池、电池模块、电池包及用电装置

Publications (1)

Publication Number Publication Date
WO2024000580A1 true WO2024000580A1 (zh) 2024-01-04

Family

ID=89383586

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/103386 WO2024000580A1 (zh) 2022-07-01 2022-07-01 隔离膜、二次电池、电池模块、电池包及用电装置

Country Status (1)

Country Link
WO (1) WO2024000580A1 (zh)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103066227A (zh) * 2012-12-26 2013-04-24 中科院广州化学有限公司 具有低温闭孔性能和良好尺寸稳定性的柔性复合陶瓷膜
CN103682217A (zh) * 2013-12-13 2014-03-26 中科院广州化学有限公司 一种动力锂离子电池用耐高温无纺布复合隔膜及其制备方法
CN103733380A (zh) * 2011-05-03 2014-04-16 株式会社Lg化学 含有多孔涂层的隔膜及含有该隔膜的电化学装置
CN104091910A (zh) * 2014-06-25 2014-10-08 中国第一汽车股份有限公司 一种陶瓷改性锂离子电池隔膜的制备方法
CN104282865A (zh) * 2014-09-03 2015-01-14 深圳中兴创新材料技术有限公司 一种凝胶聚合物涂层复合膜的制备方法及电池隔膜
CN108075088A (zh) * 2016-11-10 2018-05-25 苏州高通新材料科技有限公司 含磺化石墨烯锂盐的锂电池隔膜、其制备方法及应用
CN110993859A (zh) * 2019-12-25 2020-04-10 武汉中兴创新材料技术有限公司 一种结构改进的聚合物涂层隔膜及其制备方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103733380A (zh) * 2011-05-03 2014-04-16 株式会社Lg化学 含有多孔涂层的隔膜及含有该隔膜的电化学装置
CN103066227A (zh) * 2012-12-26 2013-04-24 中科院广州化学有限公司 具有低温闭孔性能和良好尺寸稳定性的柔性复合陶瓷膜
CN103682217A (zh) * 2013-12-13 2014-03-26 中科院广州化学有限公司 一种动力锂离子电池用耐高温无纺布复合隔膜及其制备方法
CN104091910A (zh) * 2014-06-25 2014-10-08 中国第一汽车股份有限公司 一种陶瓷改性锂离子电池隔膜的制备方法
CN104282865A (zh) * 2014-09-03 2015-01-14 深圳中兴创新材料技术有限公司 一种凝胶聚合物涂层复合膜的制备方法及电池隔膜
CN108075088A (zh) * 2016-11-10 2018-05-25 苏州高通新材料科技有限公司 含磺化石墨烯锂盐的锂电池隔膜、其制备方法及应用
CN110993859A (zh) * 2019-12-25 2020-04-10 武汉中兴创新材料技术有限公司 一种结构改进的聚合物涂层隔膜及其制备方法

Similar Documents

Publication Publication Date Title
KR101500983B1 (ko) 질소 도핑된 탄소 코팅을 포함하는 실리콘계 음극활물질의 제조방법 및 이를 포함하는 리튬이차전지
WO2024011512A1 (zh) 负极极片、制备负极极片的方法、二次电池、电池模块、电池包和用电装置
WO2023197807A1 (zh) 正极材料及其制备方法、复合正极材料、正极极片及二次电池
WO2024012166A1 (zh) 二次电池及用电装置
WO2024109500A1 (zh) 一种储能装置、储能系统及用电设备
US20240283092A1 (en) Separator and preparation method thereof, secondary battery, battery module, battery pack, and electric apparatus
US20240030437A1 (en) Positive electrode slurry and preparation method therefor, positive electrode plate, secondary battery, battery module, battery pack, and electric apparatus
US20230343925A1 (en) Carbon fiber lithium supplement film, preparation method thereof, secondary battery and power consumption apparatus including the same
WO2021195913A1 (zh) 负极材料、负极极片、电化学装置和电子装置
WO2024011350A1 (zh) 复合材料及其制备方法、电极、二次电池及用电装置
WO2023082925A1 (zh) 一种正极材料、正极极片、二次电池、电池模块、电池包及用电装置
WO2024092472A1 (zh) 复合负极活性材料、包含其的负极极片、电极组件、电池单体、电池及用电装置
WO2023134340A1 (zh) 负极活性材料、负极极片、二次电池、电池模块、电池包及其用电装置
CN116404265A (zh) 一种电化学装置和电子装置
WO2023240598A1 (zh) 改性正极材料、其制备方法、正极极片、二次电池、电池模块、电池包和用电装置
WO2024000580A1 (zh) 隔离膜、二次电池、电池模块、电池包及用电装置
WO2023137624A1 (zh) 二次电池、电池模块、电池包以及用电装置
WO2023060534A1 (zh) 一种二次电池
CN116137323A (zh) 正极补锂添加剂及其制备方法与应用
JP2023549998A (ja) リチウムイオン電池
WO2024011561A1 (zh) 正极材料组合物、正极、二次电池及用电装置
WO2023141954A1 (zh) 锂离子电池、电池模块、电池包和用电装置
WO2024174170A1 (zh) 隔离膜、二次电池及用电装置
WO2023225937A1 (zh) 负极极片及其制备方法、二次电池、电池模块、电池包及用电装置
WO2023142934A1 (zh) 正极极片、二次电池及其制备方法和含有二次电池的装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22948679

Country of ref document: EP

Kind code of ref document: A1