WO2024011404A1 - 隔离膜及使用其的二次电池、电池模块、电池包和用电装置 - Google Patents

隔离膜及使用其的二次电池、电池模块、电池包和用电装置 Download PDF

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WO2024011404A1
WO2024011404A1 PCT/CN2022/105167 CN2022105167W WO2024011404A1 WO 2024011404 A1 WO2024011404 A1 WO 2024011404A1 CN 2022105167 W CN2022105167 W CN 2022105167W WO 2024011404 A1 WO2024011404 A1 WO 2024011404A1
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optionally
isolation film
battery
graphene oxide
isolation
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PCT/CN2022/105167
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English (en)
French (fr)
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刘锋
范玉磊
王毅恒
钟韡
葛销明
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/105167 priority Critical patent/WO2024011404A1/zh
Publication of WO2024011404A1 publication Critical patent/WO2024011404A1/zh

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    • 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
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • 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 technical field of lithium batteries, and in particular to an isolation film and secondary batteries, battery modules, battery packs and electrical devices using the same.
  • Lithium-ion batteries usually include positive and negative electrode plates, an electrolyte, and an isolation film disposed between the positive and negative electrode plates.
  • the isolation film is mainly used to prevent the positive and negative electrodes from short-circuiting while allowing ions to pass freely.
  • Most of the isolation films used in the prior art are polyolefin films.
  • the polyolefin film has poor wettability with the electrolyte, and the lithium dendrites generated during battery use may penetrate the isolation film and cause a short circuit in the battery, posing a safety risk.
  • This application was made in view of the above problems, and its purpose is to provide a separator that has good wettability, mechanical properties and low resistance at the same time, so that the secondary battery using it has good Safety performance, dynamic performance and cycle performance.
  • a first aspect of the present application provides an isolation film, including a first base film that is stacked in sequence; a second base film; and a layer containing ceramic particles, graphene oxide and adhesive located between the first base film and the second base film. Adhesive coating.
  • the isolation film described in this application has a three-layer composite structure, has good electrolyte wetting performance and low resistance, and is conducive to improving the safety performance, dynamic performance and cycle performance of secondary batteries using the isolation film.
  • the mass ratio of the ceramic particles to the binder is 1:0.001-0.3, optionally 1:0.01-0.1.
  • the coating When the mass ratio of ceramic particles to binder is within the above range, it is beneficial for the coating to have appropriate adhesion, thereby better preventing the ceramic particles from "falling off".
  • the ratio of the sum of the masses of the ceramic particles and the binder to the mass of the graphene oxide is 2-11:1, optionally 2-9:1.
  • the ratio of the sum of the masses of ceramic particles and binder to the mass of graphene oxide is within the above range, it is beneficial to increase the ionic conductivity of the coating, improve the wettability of the isolation film, and enhance its resistance to lithium dendrites Ability to improve the dynamic performance and safety performance of corresponding secondary batteries.
  • the mass ratio of the graphene oxide to the ceramic particles is 1:1.5-11, optionally 1:3-5.
  • the mass ratio of graphene oxide to ceramic particles is within the above range, it is beneficial to promote the formation of intermolecular forces and hydrogen bonds between the oxygen-containing functional groups on the surface of graphene oxide and the ceramic particles, and improve the stability of the ceramic particles on the isolation film.
  • the adhesion of the coating can be improved, thereby improving the overall adhesion of the coating, and also helping to prevent the stacking of graphene oxide sheets from clogging the micropores of the isolation film.
  • the graphene oxide is a graphene oxide sheet, and optionally, the maximum lateral dimension of the graphene oxide sheet is 0.01-10 ⁇ m.
  • the small-diameter graphene oxide can prevent the graphite from covering the micropores on the isolation membrane and thus causing the air permeability of the isolation membrane to decrease, thus avoiding the obstruction of ion transmission and the increase in the resistance of the isolation membrane.
  • the ceramic particles are selected from one or more of the oxides, nitrides or oxo-acid salts of the following elements: Si, Fe, Sn, Ti, Cu, Mg, Ge , Zn, Zr and B;
  • titanium dioxide TiO 2
  • silicon dioxide SiO 2
  • tin dioxide SiO 2
  • zinc oxide ZnO
  • zirconium oxide ZrO 2
  • lithium titanate lithium titanate
  • the mechanical strength, electrolyte wettability and electrochemical stability of the isolation membrane can be effectively improved.
  • the particle size of the ceramic particles is 0.01-10 ⁇ m, optionally 0.05-0.5 ⁇ m.
  • the particle size of the ceramic particles is within the above range, it will not only help avoid “powder loss” caused by excessive particle size, but also help prevent the particle size from being too small to block the base membrane channel and worsen the dynamic performance.
  • the binder is selected from dopamine hydrochloride, polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoroethylene Fluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate, styrene-butadiene rubber, sodium polyacrylate, polymethacrylic acid, polyacrylamide, polyvinyl alcohol, sodium alginate , carboxymethyl chitosan, carboxymethyl cellulose sodium, one or more.
  • the thickness of the coating is 0.1-10 ⁇ m, optionally 1-6 ⁇ m.
  • the thickness of the coating When the thickness of the coating is within the above range, it can not only effectively consume lithium dendrites to prevent them from penetrating the isolation film and causing safety problems, but also help prevent the coating from causing a significant increase in the resistance of the isolation film.
  • the first base film and the second base film are each independently selected from polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyamide, and One or more polyesters.
  • the first base film and/or the second base film undergoes an infiltration treatment with a graphene oxide dispersion.
  • Pretreating the base film with a dispersion of graphene oxide can improve the composite efficiency of the coating and the base film, reduce the use of binders, and thereby reduce the resistance of the isolation film.
  • the thickness of the first base film and/or the second base film is 3-30 ⁇ m, optionally 5-25 ⁇ m.
  • the isolation film satisfies: ⁇ s ⁇ 10 7 m ⁇ cm, optionally ⁇ s ⁇ 5 ⁇ 10 6 m ⁇ cm, where ⁇ s represents the ion resistivity of the isolation film.
  • ⁇ s is within the above range, the ion resistivity of the isolation film is small, which is beneficial to improving the dynamic performance of the corresponding secondary battery.
  • a second aspect of the present application provides a secondary battery, including the separator film of the first aspect of the present application.
  • a third aspect of the present application provides a battery module including the secondary battery of the second aspect of the present application.
  • a fourth aspect of the present application provides a battery pack, including at least one of the secondary battery of the second aspect of the present application or the battery module of the third aspect of the present application.
  • a fifth aspect of the present application provides an electrical device, including at least one of the secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application.
  • the isolation membrane of this application has a three-layer composite structure, and the coating in the middle includes ceramic particles, graphene oxide and a binder.
  • ceramic particles can promote the infiltration of the electrolyte into the isolation membrane.
  • they can also effectively consume the lithium dendrites produced, preventing the lithium dendrites from penetrating the isolation membrane, and improving safety performance.
  • the surface of graphene oxide in the coating is rich in various polar groups. On the one hand, it can further promote the infiltration of the electrolyte into the base film. On the other hand, it can help reduce resistance through the following effects, thereby improving the performance of the corresponding battery.
  • graphene oxide itself can be composited with the base film through van der Waals forces, reducing the use of binders; second, graphene oxide can provide a large number of channels for free transmission of ions, improving the ionic conductivity of the isolation membrane. .
  • the coating is located between the first base film and the second base film.
  • the base film itself can exist as a "barrier layer", which can effectively prevent the ceramic particles from direct contact with the positive and negative electrode plates. On the one hand, it helps to further improve the Corresponding to the safety performance of secondary batteries, on the other hand, it also helps to avoid many side reactions, improve the stability of corresponding batteries during use, and improve cycle performance.
  • the battery modules, battery packs and electrical devices of the present application include the secondary battery provided by the present application, and thus have at least the same advantages as the secondary battery.
  • Figure 1 is a schematic diagram of the isolation film of the present application.
  • FIG. 2 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 3 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 2 .
  • Figure 4 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 5 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 6 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 5 .
  • FIG. 7 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.
  • 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 the ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges of 60-110 and 80-120 are also expected. Furthermore, 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: 1-3, 1-4, 1-5, 2- 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.
  • two-dimensional material refers to one or more layers, in which the atoms in each layer are tightly bonded with neighboring atoms in the layer and have one dimension (i.e. A material whose thickness) is on the nanometer scale or smaller and the remaining two dimensions are usually on larger scales;
  • lateral dimension refers to the lateral size of a flake of a two-dimensional material.
  • 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).
  • the inventor found that by applying a coating containing ceramic particles, graphene oxide and a binder between the two base films, the infiltration of the electrolyte into the isolation film can be promoted and lithium dendrites can be effectively avoided.
  • the crystal penetrates the isolation film, and can avoid the application of coatings or the use of a large amount of adhesives, which will cause a significant increase in the resistance of the isolation film. It can also avoid the occurrence of many side reactions, improve the operation stability of the corresponding battery, thereby improving the application of the isolation film. Safety performance, kinetic performance and cycle performance of secondary batteries.
  • a first aspect of the present application provides an isolation film, including a first base film that is stacked in sequence; a second base film; and a layer containing ceramic particles, graphene oxide and adhesive located between the first base film and the second base film. Adhesive coating.
  • the isolation membrane of this application has a three-layer composite structure, and the coating in the middle includes ceramic particles, graphene oxide and a binder.
  • ceramic particles can promote the infiltration of the electrolyte into the isolation membrane and improve the heat resistance and mechanical properties of the isolation membrane.
  • they can also effectively consume the generated lithium dendrites to prevent the lithium dendrites from penetrating the isolation membrane and improve safety performance.
  • the surface of graphene oxide in the coating is rich in various polar groups. On the one hand, it can further promote the infiltration of the electrolyte into the base film. On the other hand, it can help reduce resistance through the following effects, thereby improving the performance of the corresponding battery.
  • graphene oxide itself can be composited with the base film through van der Waals forces, reducing the use of binders; second, graphene oxide can provide a large number of channels for free transmission of ions, improving the ionic conductivity of the isolation membrane. .
  • the coating is located between the first base film and the second base film.
  • the base film itself can exist as a "barrier layer", which can effectively prevent the ceramic particles from direct contact with the positive and negative electrode plates. On the one hand, it helps to further improve the Corresponding to the safety performance of secondary batteries, on the other hand, it also helps to avoid many side reactions, improve the stability of corresponding batteries during use, and improve cycle performance.
  • the mass ratio of the ceramic particles to the binder is 1:0.001-0.3, optionally 1:0.01-0.1.
  • the ratio may be 1:0.001, 1:0.005, 1:0.006, 1:0.01, 1:0.013, 1:0.017, 1:0.02, 1:0.026, 1:0.033, 1:0.05, 1: The range consisting of 0.06, 1:0.1 or 1:0.3 and any two of the above ratios.
  • the ratio of the sum of the masses of the ceramic particles and the binder to the mass of the graphene oxide is 2-11:1, optionally 2-9:1.
  • the ratio may be 2:1, 3:1, 3.1:1, 5:1, 5.1:1, 5.3:1, 5.5:1, 6.5:1, 8:1, 9:1, 10:1 1 or 11:1 and any two of the above ratios.
  • the mass ratio of the graphene oxide to the ceramic particles is 1:1.5-11, optionally 1:3-5.
  • the ratio may be 1:1.5, 1:1.95, 1:3, 1:5, 1:8, 1:8.95, 1:9, 1:10 or 1:11 and any two of the above ratios. range composed of.
  • the surface of graphene oxide is rich in oxygen-containing functional groups.
  • the mass ratio of graphene oxide to ceramic particles is within the above range, it is beneficial to promote the formation of intermolecular forces and hydrogen between the oxygen-containing functional groups on the surface of graphene oxide and ceramic particles.
  • the bonding effect improves the adhesion of ceramic particles on the isolation film, thereby improving the overall adhesion of the coating, and also helps prevent the stacking of graphene oxide sheets from clogging the micropores of the isolation film.
  • the mass ratio of graphene oxide to ceramic particles is within the above range, it is also beneficial to improve the function of the coating to consume lithium dendrites.
  • the content of the graphene oxide is 5-40%, optionally 15-30% based on the total weight of the coating;
  • the content of the ceramic particles is 25-95%, optionally 70-85%;
  • the content of the binder is 0.001-8%, optionally 0.01%-0.5%.
  • the mass ratio of graphene oxide:ceramic particles:binder is 0.09-1:1:0.001-0.3.
  • the above ratio may be 0.1:1:0.001, 0.2:1:0.001, 0.2:1:0.01, 0.2:1:0.1, 0.2:1:0.3, 0.3:1:0.3, 0.5:1:0.2 or 1 ⁇ 1:0.3 and the range consisting of any two of the above ratios.
  • the graphene oxide is a graphene oxide sheet, and optionally, the maximum lateral dimension of the graphene oxide sheet is 0.01-10 ⁇ m.
  • the surface of graphene oxide is rich in oxygen-containing functional groups such as hydroxyl groups, carboxyl groups, and aldehyde groups, so it can effectively improve the lyophilicity of the isolation membrane and enable the electrolyte to quickly infiltrate the isolation membrane.
  • the stacked graphene oxide sheets create a large number of gaps so that lithium ions can be freely transported in the pores of the sheets, improving the ionic conductivity of the isolation membrane.
  • the small-diameter graphene oxide helps prevent graphene from covering the micropores on the isolation membrane and thereby reducing the air permeability of the isolation membrane, thus avoiding obstruction of ion transmission and a substantial increase in the resistance of the isolation membrane.
  • the ceramic particles are selected from one or more of the oxides, nitrides or oxo acid salts of the following elements: Si, Fe, Sn, Ti, Cu, Mg, Ge , Zn, Zr and B;
  • titanium dioxide TiO 2
  • silicon dioxide SiO 2
  • tin dioxide SiO 2
  • zinc oxide ZnO
  • zirconium oxide ZrO 2
  • lithium titanate lithium titanate
  • the first base film and the second base film have strong hydrophobicity and poor affinity with the highly polar electrolyte, which results in the base film being unable to absorb and retain the electrolyte.
  • the ceramic particles described in this application have strong hydrophilicity, which is conducive to significantly improving the electrolyte wettability of the isolation membrane.
  • lithium dendrites will inevitably be produced. If left unchecked, lithium dendrites will eventually contact and puncture the isolation film, causing the positive and negative electrodes to come into contact, causing safety issues.
  • the components contained in the ceramic particles described in this application, such as silica, can undergo a lithium insertion reaction and consume the generated lithium dendrites in a timely manner, thus improving the safety performance of the corresponding battery.
  • reaction mechanism of ceramic particles consuming lithium dendrites described in this application can be divided into alloying reaction mechanism, intercalation reaction mechanism and redox mechanism:
  • tin dioxide tin dioxide
  • tin element and Li 2 O are first generated, and then the tin element reacts with Li+ to form Li 4.4 Sn compound.
  • Ceramic materials of the intercalation reaction mechanism are mainly SiO 2 , TiO 2 , lithium titanate, etc.
  • Transformation reaction mechanism A redox reaction occurs between metal oxides and Li + to generate metal elements and Li 2 O.
  • the chemical reaction formula is:
  • the particle size of the ceramic particles is 0.01-10 ⁇ m, optionally 0.05-0.5 ⁇ m.
  • the particle size of the ceramic particles When the particle size of the ceramic particles is too large, the slurry of the prepared coating has a high viscosity, and the uniformity is not easy to ensure, making it difficult to coat the isolation film. In addition, the phenomenon of "powder falling off” is prone to occur during the coating process of the isolation film, and the powder is difficult to adhere to the surface of the isolation film, resulting in unsatisfactory coating results and difficulty in meeting expectations. If the particle size is too small, when coating ceramic particles, the ceramic particles will block the pores on the surface of the organic microporous material, reduce the air permeability of the isolation membrane, thereby blocking the ion transmission channel, reducing the battery capacity and cycle life. There are obvious losses.
  • the introduction of the ceramic particles is beneficial to increasing the porosity of the isolation membrane, accelerating the diffusion of Li + , and improving the ion conductivity of the isolation membrane.
  • the binder is selected from dopamine hydrochloride, polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoroethylene Fluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate, styrene-butadiene rubber, sodium polyacrylate, polymethacrylic acid, polyacrylamide, polyvinyl alcohol, sodium alginate , carboxymethyl chitosan, carboxymethyl cellulose sodium, one or more.
  • the thickness of the coating is 0.1-10 ⁇ m, optionally 1-6 ⁇ m.
  • the thickness of the coating When the thickness of the coating is within the above range, it can not only effectively consume lithium dendrites to prevent them from penetrating the isolation film and causing safety problems, but also help prevent the coating from causing a significant increase in the resistance of the isolation film.
  • the first base film and the second base film are each independently selected from polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyamide, and One or more polyesters.
  • the first base film and/or the second base film undergoes an infiltration treatment with a graphene oxide dispersion.
  • Pretreating the base film with a dispersion of graphene oxide can make the surface of the base film contain many polar groups, increase the hydrophilicity of the base film, and thereby improve the wettability of the base film with the electrolyte.
  • the surface of the base film contains many polar groups, which help to improve the composite efficiency of the coating and the base film, reduce the use of binders, and thereby reduce the resistance of the isolation film.
  • the weight average molecular weight of the first base film and the second base film is 100,000-1,000,000.
  • the weight average molecular weight can be measured by methods commonly used in the art, for example, it can be measured by gel permeation chromatography according to GB/T 21863-2008.
  • the thickness of the first base film and/or the second base film is 3-30 ⁇ m, optionally 5-25 ⁇ m.
  • the thickness of the separator is too small, the mechanical stability of the separator may be poor, and it may be difficult to fully exert the role of the separator in separating the positive and negative electrodes. If the thickness of the isolation film is too large, the resistance of the isolation film may increase, making it more difficult for lithium ions to transmit through the isolation film, resulting in a decrease in battery performance.
  • the isolation film satisfies: ⁇ s ⁇ 10 7 m ⁇ cm, optionally ⁇ s ⁇ 5 ⁇ 10 6 m ⁇ cm, where ⁇ s represents the ion resistivity of the isolation film.
  • ⁇ s is within the above range, the ion resistivity of the isolation film is small, which is beneficial to improving the dynamic performance of the corresponding secondary battery.
  • this application also provides a method for preparing the isolation film described in this application, which at least includes the following steps:
  • Step 1 Thoroughly mix graphene oxide, ceramic particles and binder in an appropriate amount of solvent at a mass ratio of 0.09-1:1:0.001-0.3 to obtain a mixed slurry;
  • Step 2 Coat the mixed slurry obtained in Step 1 on one surface of the first base film and the second base film;
  • Step 3 Laminate the first base film and the second base film obtained in Step 2 along the coating side, hot-press and dry to remove the solvent.
  • the solvent described in step 1 is water, N-N dimethylformamide (DMF), N-methylpyrrolidone (NMP), etc.
  • the graphene oxide in step 1 is a dispersion of graphene oxide.
  • the solid content of the graphene oxide dispersion is 0.1-5%, optionally 0.3-3%.
  • the graphene oxide dispersion can be obtained by adding graphene oxide to a solvent and then using ultrasonic to disperse it evenly.
  • the solvent in the graphene oxide dispersion may be selected from one or more of water, ethanol, isopropanol, n-butanol, and isobutanol.
  • the first base film and the second base film are pretreated using a dispersion of graphene oxide.
  • the dispersion liquid for pretreating the base film is an aqueous dispersion of graphene oxide or an isopropyl alcohol dispersion of graphene oxide.
  • the pretreatment refers to completely immersing the base film into the dispersion of graphene oxide and keeping it for 15-120 s, optionally 30-90 s, and then taking it out to dry.
  • the coating in step 2 can be performed by coating methods commonly used in the art, such as knife coating, roller coating, or extruder coating.
  • the hot pressing in step 3 is performed at a temperature of 90-150°C, optionally 120-140°C.
  • the coating density of the coating on the isolation film obtained in step 3 is 1.0-6.0g/m 2 , optionally 1.5-4.5g/m 2 .
  • the mass ratio of graphene oxide, ceramic particles and binder is 0.09-1:1:0.001-0.3.
  • the ratio may be 0.2:1:0.02, 0.33:1:0.033, 1.125:1:0.0125, 0.1:1:0.001, 0.2:1:0.01, 0.2:1:0.06, 0.2:1:0.02, 0.2:1:0.001, 0.2:1:0.006, 0.5:1:0.03, 0.1:1:0.006 or 0.09:1:0.004 and any two of the above ratios.
  • a second aspect of the present application provides a secondary battery, which includes the isolation film described in the first aspect of the present application.
  • a secondary battery in addition to a separator, includes a positive electrode plate, a negative electrode plate, and an electrolyte.
  • the isolation film described in this application can also be used in lithium metal batteries instead of traditional isolation films.
  • the negative electrode of the lithium metal battery may be lithium metal or lithium alloy, or may have no negative electrode.
  • Corresponding cathode materials are described below. If it is a lithium metal battery without anode, the cathode material needs to provide a lithium source.
  • the preparation of the secondary battery can be carried out by methods commonly used in the art.
  • the positive electrode sheet, the negative electrode sheet and the separator can be made into an electrode assembly through a winding process or a lamination process, and then the electrolyte is injected into the electrode assembly. and sealed to prepare a secondary battery.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite 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 a polymer material base layer (such as polypropylene (PP), polyethylene terephthalate Glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate Glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode material is a compound that can reversibly intercalate and deintercalate Li + .
  • the cathode active material may be a cathode active material known in the art for batteries.
  • Examples include lithium-containing composite oxides represented by Li x MO 2 or Li y M 2 O 4 (where M is a transition metal, 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 2), and spinel-like oxidation.
  • Examples include lithium cobalt oxides such as LiCoO2 , lithium manganese oxides such as LiMn2O4 , lithium nickel oxides such as LiNiO2 , lithium titanium oxides such as Li4 / 3Ti5/ 3O4 , and lithium manganese nickel.
  • Composite oxide, lithium manganese nickel cobalt composite oxide; materials with olivine crystal structure such as LiMPO 4 (M Fe, Mn, Ni), etc.
  • the cathode active material is a lithium-containing composite oxide with a layered structure or a spinel-like structure, such as LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , LiNi 1/2 Mn 1/ Lithium manganese nickel cobalt composite oxide represented by LiNi 1/3 Mn 1/3 Co 1/3 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2, etc. , or LiNi 1-xyz Co x Al y Mg z O 2 (in the formula, 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 0.1, 0 ⁇ z ⁇ 0.1, 0 ⁇ 1-xyz ⁇ 1) and other lithium-containing composite oxides .
  • LiCoO 2 , LiMn 2 O 4 LiNiO 2
  • LiNi 1/2 Mn 1/ Lithium manganese nickel cobalt composite oxide represented by LiNi 1/3 Mn 1/3 Co 1/3 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2, etc.
  • lithium-containing composite oxides in which part of the constituent elements in the above-mentioned lithium-containing composite oxide is replaced by additional elements such as Ge, Ti, Zr, Mg, Al, Mo, and Sn are also included in the scope of the present application.
  • positive electrode active materials In addition to the above-mentioned positive electrode active materials, other conventional materials that can be used as positive electrode active materials of batteries may 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. For example, by simultaneously using a lithium-containing composite oxide with a layered structure and a lithium-containing composite oxide with a spinel structure, it is possible to achieve both increased capacity and improved safety.
  • the mass percentage of the cathode active material in the cathode membrane is 75% to 99%, optionally 80% to 97%.
  • the positive electrode film 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 conductive agent accounts for 0.05-5%, optionally 0.5-3%, of the total weight of the positive electrode film layer.
  • the positive electrode membrane layer optionally further includes a binder, such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoroethylene Binders commonly used in the battery field include propylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and polyethylene oxide.
  • a binder such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoroethylene Binders commonly used in the battery field include propylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and polyethylene oxide.
  • the binder accounts for 0.1-3.5%, optionally 0.5-2.5%, of the total weight of the positive electrode film layer.
  • 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 includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite 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 electrode material is a compound capable of intercalating and deintercalating lithium metal and lithium.
  • the negative active material may be a negative active material known in the art for batteries.
  • various materials such as alloys of aluminum, silicon, and tin, or oxides, and carbon materials can be used as the negative electrode active material.
  • examples of the oxide include titanium dioxide
  • examples of the carbon material include graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesophase carbon microbeads, and the like.
  • 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 mass percentage of the negative active material in the positive electrode membrane is 75% to 99%, optionally 80% to 97%.
  • the negative electrode film 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 conductive agent accounts for 0.05-5%, optionally 0.5-3%, of the total weight of the negative electrode film layer.
  • the negative electrode film layer optionally further includes a binder, such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoroethylene Binders commonly used in the battery field include propylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and polyethylene oxide.
  • a binder such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoroethylene Binders commonly used in the battery field include propylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and polyethylene oxide.
  • the binder accounts for 0.1-3.5%, optionally 0.5-2.5%, of the total weight of the negative electrode film layer.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the mass percentage of the thickener in the negative electrode membrane is 0.04% to 5%, optionally 0.5% to 3%.
  • 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.
  • a non-aqueous solvent (organic solvent) is used as the non-aqueous electrolyte solution.
  • Non-aqueous solvents include carbonates, ethers, etc.
  • carbonates include cyclic carbonates and chain carbonates.
  • cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, ⁇ -butyrolactone, sulfur esters (ethylene glycol sulfide), and the like.
  • chain carbonates include low-viscosity polar chain carbonates and aliphatic branched carbonate compounds, such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
  • a mixed solvent of cyclic carbonate (especially ethylene carbonate) and linear carbonate is particularly preferred.
  • ethers examples include tetraethylene glycol dimethyl ether (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxopentane (DOL), and the like.
  • TEGDME tetraethylene glycol dimethyl ether
  • DME ethylene glycol dimethyl ether
  • DOL 1,3-dioxopentane
  • chain alkyl esters such as methyl propionate, chain phosphate triesters such as trimethyl phosphate, nitrile solvents such as 3-methoxypropionitrile, and dendritic solvents can also be used.
  • the compound is a non-aqueous solvent (organic solvent) such as a branched compound having an ether bond.
  • fluorine-based solvents can also be used.
  • fluorine-based solvents include H(CF 2 ) 2 OCH 3 , C 4 F 9 OCH 3 , H(CF 2 ) 2 OCH 2 CH 3 , H(CF 2 ) 2 OCH 2 CF 3 , H( CF 2 ) 2 CH 2 O (CF 2 ) 2 H, etc., or CF 3 CHFCF 2 OCH 3 , CF 3 CHFCF 2 OCH 2 CH 3 and other straight-chain (perfluoroalkyl) alkyl ethers, such as 2-tris Fluoromethyl hexafluoropropyl methyl ether, 2-trifluoromethyl hexafluoropropyl ethyl ether, 2-trifluoromethyl hexafluoropropyl propyl ether, 3-trifluoromethyl octafluorobutyl methyl ether, 3-trifluoromethyl ether Methyl octafluorobuty
  • lithium salts such as lithium perchlorate, organoboron lithium salt, lithium salt of fluorine-containing compound, and lithium imide salt are preferred.
  • electrolyte salts examples include LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiC 2 F 4 (SO 3 ) 2 , LiN( C 2 F 5 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiC n F 2n+1 SO 3 (n ⁇ 2), LiN(R f OSO 2 ) 2 (where R f is fluoroalkyl base) etc.
  • fluorine-containing organic lithium salts are particularly preferred. Fluorine-containing organic lithium salts are easily soluble in non-aqueous electrolytes due to their high anion polarity and easy separation into ions.
  • the concentration of the electrolyte lithium salt in the non-aqueous electrolyte is, for example, above 0.3 mol/L (mol/L), more preferably above 0.7 mol/L; below 1.7 mol/L, more preferably below 1.2 mol/L. .
  • concentration of the electrolyte lithium salt is too low, the ionic conductivity is too small.
  • concentration of the electrolyte lithium salt is too high, there is a concern that the incompletely dissolved electrolyte salt may precipitate.
  • the electrolyte may optionally include additives, which are not specifically limited in this application.
  • 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.
  • a third aspect of the present application provides a battery module including the secondary battery of the second aspect of the present application.
  • the battery module can be prepared by methods commonly used in the art.
  • a fourth aspect of the present application provides a battery pack, including at least one of the secondary battery of the second aspect of the present application or the battery module of the third aspect of the present application.
  • the battery pack can be prepared by methods commonly used in the art.
  • a fifth aspect of the present application provides an electrical device, including at least one selected from the secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application. kind.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 2 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. 4 is a battery module 3 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.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present 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 may include 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 carts). , 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. 7 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.
  • IPA isopropyl alcohol
  • Step 2 Preparation of mixed slurry
  • An aqueous dispersion of GO with a solid content of 1wt% (the preparation method is the same as step 1, only water is used as the solvent, based on the wet weight including water, the same below), SiO 2 (400nm, based on the dry weight, the same below),
  • the mixed binder (based on the dry weight of the mixed binder, the same below) is mixed at a mass ratio of 100:5:0.1, and stirred at 800 rpm for 30 minutes to make the slurry evenly mixed for later use.
  • the preparation method of the mixed binder is: a mixed solution of 0.75g dopamine hydrochloride, 0.2g sodium carboxymethylcellulose (CMC), 10ml of deionized water and ethanol (1:1, v:v) (water-based solvent) mix well. Then, a NaOH aqueous solution with a concentration of 1 mol/L was used to adjust the pH to 8.5 to obtain a mixed binder.
  • step 2 Except that the silica particle size in step 2 is changed to 700 nm, other steps in embodiment 2 are the same as in embodiment 1.
  • step 2 is changed to 200 nm
  • steps in embodiment 3 are the same as in embodiment 1.
  • Example 4 Except that in step 2, the ceramic particles are changed from silica to ferric oxide (particle diameter is about 100 nm), other steps of Example 4 are the same as Example 1.
  • Iron dioxide can perform an alloying reaction with lithium dendrites. It has high specific capacity, good stability, and low ionic conductivity, which is beneficial to the consumption of lithium dendrites and reduces the internal resistance caused by the isolation film.
  • Example 5 Except that in step 2, the ceramic particles are changed from silica to tin dioxide (particle diameter is about 100 nm), other steps of Example 5 are the same as Example 1.
  • Example 6 Except that in step 2, the ceramic particles are changed from silica to titanium dioxide (particle diameter is about 100 nm, anatase type), other steps of Example 6 are the same as Example 1.
  • Titanium dioxide can undergo an intercalation reaction with lithium dendrites to generate lithium titanate. It has high theoretical capacity and stable structure, and the oxide structure will not change much after lithium insertion.
  • Example 7 Except that the ceramic particles in step 2 are changed from silicon dioxide to copper oxide (CuO, with a particle size of about 150 nm), other steps in Example 7 are the same as in Example 1.
  • Copper oxide and lithium undergo a conversion reaction to produce amorphous Li 2 O and nano-scale metallic copper particles.
  • the produced nano-copper particles can further react with Li 2 O to form oxides, which have high specific capacity and good performance. cycle performance.
  • Example 8 Except that in step 1, the dispersion of graphene oxide is not used to hydrophilize the polypropylene membrane, the other conditions of Example 8 are the same as Example 1.
  • step 2 Adjust the mass ratio of the 1wt% GO aqueous dispersion in step 2 (the preparation method is the same as step 1, only using water as the solvent), SiO 2 (400nm), and mixed binder as follows:
  • Example 12 100:5:0.05
  • step 3 Except that the coating thickness in step 3 was changed to 4 ⁇ m, 5 ⁇ m, and 6 ⁇ m, the remaining steps were the same as in Example 1.
  • Example 25 The conditions of Example 25 were the same as those of Example 1, except that the ceramic particles in step 2 were changed from silica to alumina (particle diameter about 400 nm).
  • the positive active material lithium iron phosphate (calculated as LiFePO 4 ), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) at a mass ratio of 96.5:2:1.5, and dissolve them in the solvent N-methylpyrrolidone (That is, NMP), and stir thoroughly to mix evenly to obtain a positive electrode slurry. Then, the positive electrode slurry is evenly coated on the aluminum foil, dried, cold pressed, and cut to obtain the positive electrode piece. The coated surface density of the obtained pole piece was 19.5 mg/cm 2 and the compacted density was 2.4 g/cm 3 .
  • the negative electrode slurry is evenly coated on the negative electrode current collector copper foil, and then dried, cold pressed, and cut to obtain negative electrode sheets.
  • the coated surface density of the obtained pole piece was 9.8 mg/cm 2 and the compacted density was 1.65 g/cm 3 .
  • the separators prepared in the Examples and Comparative Examples of the present application were used as separators for secondary batteries.
  • 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.
  • the size of the obtained secondary battery was 60 ⁇ 130 ⁇ 4 mm.
  • tested according to ASTM D882-09 specification Cut the tested isolation film into a size with a width of 10mm and a length of ⁇ 150mm, and use a universal tensile machine to stretch it at a rate of 500mm/min. After obtaining the maximum load value when the sample breaks, divide it by the cross-sectional area of the isolation film. (sample width ⁇ specimen thickness), calculate the tensile strength of the isolation film.
  • Dv50 The diameter of particles accounting for 50% of the total volume is greater than this value, and the diameter of particles accounting for 50% of the total volume is smaller than this value.
  • Dv50 represents the median particle size of the powder
  • the angle of the scattered light is inversely proportional to the diameter of the particle, and the intensity of the scattered light attenuates logarithmically as the angle increases.
  • the energy distribution of the scattered light is directly related to the distribution of the particle diameter.
  • Coating surface density ( ⁇ ) coating weight (m)/coating area (A).
  • Test method Use electrochemical impedance spectroscopy to study the impact of the isolation film in the battery on lithium ion permeability. From the electrochemical impedance spectrum measured using the AC method, the internal resistance of the battery (related to the resistance of the isolation film) can be obtained, so this method can be used to obtain the charge transfer resistance of the battery. Tested using IVIUM electrochemical workstation, the frequency is 0.1Hz-100kHz.
  • the restricted symmetrical battery EIS method is used to measure the Rs of different isolation film layers (n) as the isolation film resistance.
  • the slope k is obtained by plotting Rs and n.
  • the actual test result is usually the ionic resistance of the battery, that is, the volume resistance.
  • the ion resistance (R b ) obtained from the experimental test is the sum of the resistance of the isolation film (R s ) and the resistance of the electrolyte in the battery (R e ), as shown below
  • ⁇ s is the resistivity of the isolation film
  • S is the effective area of the isolation film
  • d is the average thickness of the isolation film.
  • the solid content can be tested according to GB/T 1725-2007 "Determination of non-volatile content of paints, varnishes and plastics".
  • Discharge conditions Discharge in constant current mode at different discharge rates (C-rate: 0.1C/1C/3C) to 2.5V, and cycle 200 times.
  • the isolation membrane pretreated with graphene oxide dispersion can more effectively contact the ceramic-graphene oxide coating, which helps to better improve the overall performance of the isolation membrane; 2) compared to Aluminum oxide, using other ceramic particles of this application can better improve the mechanical properties and wettability of the isolation membrane; 3) Graphene oxide helps to improve the adhesion, wettability and ion conductivity of the isolation membrane; 4) By Adjusting the ratio of graphene oxide, binder and ceramic particles can further improve the overall performance of the isolation membrane.
  • the secondary battery corresponding to the separator coated with the graphene oxide-ceramic particle hybrid coating has a high Coulombic efficiency, which can still remain above 99% after 200 cycles at low rates; The Coulombic efficiency at high rates is also higher, indicating that the secondary battery has good cycle performance and longer service life.
  • the secondary battery using the isolation film of the present application has higher power, indicating that its dynamic performance is better.
  • the lithium dendrites generated during the cycle can be consumed in time, so the corresponding secondary batteries have good safety performance.

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Abstract

本申请提供一种隔离膜，包括依次层叠设置的第一基膜；包含陶瓷颗粒、氧化石墨烯和粘结剂的涂层；和第二基膜。本申请所述隔离膜具备良好的电解液浸润性，可有效抑制锂枝晶的生长，并且具备较小的电阻，可有效改善相应电池的安全性能、动力学性能和循环性能。本申请还提供使用本申请所述隔离膜的二次电池、电池模块、电池包和用电装置。

Description

隔离膜及使用其的二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及锂电池技术领域，尤其涉及一种隔离膜及使用其的二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着锂离子电池的应用范围越来越广泛，锂离子电池在风力、火力、水力、太阳能电站等储能系统以及电动工具、电动自行车等多个领域得到了非常广泛的应用。锂离子电池通常包括正负极极片、电解液和设置在正负极极片之间的隔离膜，所述隔离膜主要用于防止正负极短路，同时使离子自由通过。现有技术中使用的隔离膜多为聚烯烃膜。然而，聚烯烃膜与电解液的浸润性较差，且电池使用过程中产生的锂枝晶可能刺透隔离膜而造成电池短路，引发安全风险。
为解决上述问题，技术人员通常会在隔离膜上施加一层涂层来促进电解液对隔离膜的浸润，并避免锂枝晶刺透隔离膜。陶瓷颗粒就是技术人员通常施加的涂层之一。然而，由于陶瓷颗粒与聚烯烃膜之间的粘结性差，“掉粉”比较严重。为此，需要引入粘结剂增大陶瓷颗粒与聚烯烃膜之间的粘结力来减少掉粉，但大量使用粘结剂又会导致隔离膜电阻增大，恶化二次电池的动力学性能。
由此可见，如何开发出一种同时具备良好的浸润性能和较低电阻的隔离膜仍是研发人员亟需解决的一项课题。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种隔离膜，所述隔离膜同时具备良好的浸润性能、机械性能和较低的电阻，从而使得应用其的二次电池具有良好的安全性能、动力学性能和循环性能。
本申请的第一方面提供一种隔离膜，包括依次层叠设置的第一基 膜；第二基膜；以及位于第一基膜和第二基膜之间的包含陶瓷颗粒、氧化石墨烯和粘结剂的涂层。
本申请所述隔离膜具备三层复合结构，具备良好的电解液浸润性能和较低的电阻，有利于提高应用所述隔离膜的二次电池的安全性能、动力学性能和循环性能。
在任意实施方式中，可选地，所述陶瓷颗粒与所述粘结剂的质量之比为1∶0.001-0.3，可选为1∶0.01-0.1。
当陶瓷颗粒与粘结剂的质量之比在上述范围内时，有利于使涂层具备适当的粘结性，从而更好地避免陶瓷颗粒“掉粉”。
在任意实施方式中，可选地，所述陶瓷颗粒与所述粘结剂的质量之和与所述氧化石墨烯的质量之比为2-11∶1，可选2-9∶1。
当陶瓷颗粒与粘结剂的质量之和与氧化石墨烯的质量之比处于上述范围内时，有利于增大所述涂层的离子电导率，提高隔离膜浸润性，增强其耐锂枝晶能力，改善对应二次电池的动力学性能和安全性能。
在任意实施方式中，可选地，所述氧化石墨烯与陶瓷颗粒的质量之比为1∶1.5-11，可选为1∶3-5。
当氧化石墨烯与陶瓷颗粒的质量之比在上述范围内时，有利于促进氧化石墨烯表面的含氧官能团与陶瓷颗粒之间形成分子间作用力和氢键作用，提高陶瓷颗粒在隔离膜上的粘结性，进而提高涂料整体的粘结性，还有利于避免氧化石墨烯片堆叠堵塞隔离膜微孔。
在任意实施方式中，可选地，所述氧化石墨烯为氧化石墨烯片，可选地，所述氧化石墨烯片的最大横向尺寸为0.01-10μm。
小片径的氧化石墨烯能防止石墨覆盖隔离膜上的微孔及因此导致隔离膜透气性下降，从而避免离子传输受阻和隔离膜阻抗上升。
在任意实施方式中，可选地，所述陶瓷颗粒选自以下元素的氧化物、氮化物或含氧酸盐中的一种或多种：Si、Fe、Sn、Ti、Cu、Mg、Ge、Zn、Zr和B；
可选选自Si的氧化物、Si的氮化物、Fe的氧化物、Fe的氮化物、Fe的含氧酸盐、Sn的氧化物、Ti的氧化物、Ti的氮化物、Ti的含氧 酸盐、Cu的氧化物、Cu的氮化物、Mg的氧化物、Ge的氧化物、Zn的氧化物、锆的氧化物、及氮化硼中的一种或多种；
更可选选自二氧化钛(TiO 2)、二氧化硅(SiO 2)、二氧化锡(SnO 2)、氧化锌(ZnO)、氧化锆(ZrO 2)、钛酸锂中的一种或多种。
当陶瓷颗粒选自上述材料时，可有效提高隔离膜的机械强度、电解液浸润性和电化学稳定性。
在任意实施方式中，可选地，所述陶瓷颗粒的粒径为0.01-10μm，可选0.05-0.5μm。
当陶瓷颗粒的粒径在上述范围内时，既有利于避免由于粒径过大而导致“掉粉”，又有利于避免粒径过小堵塞基膜通道，恶化动力学性能。
在任意实施方式中，可选地，所述粘结剂选自盐酸多巴胺、聚偏二氟乙烯、聚四氟乙烯、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、含氟丙烯酸酯、丁苯橡胶、聚丙烯酸钠、聚甲基丙烯酸、聚丙烯酰胺、聚乙烯醇、海藻酸钠、羧甲基壳聚糖、羧甲基纤维素钠中的一种或多种。
在任意实施方式中，可选地，所述涂层的厚度为0.1-10μm，可选1-6μm。
当涂层的厚度在上述范围内时，既可有效消耗锂枝晶，避免其穿透隔离膜，引发安全问题，又有利于避免涂层导致隔离膜电阻大幅增加。
在任意实施方式中，可选地，所述第一基膜和第二基膜各自独立地选自聚乙烯、聚丙烯、聚四氟乙烯、聚偏氟乙烯、聚氯乙烯、聚酰胺、以及聚酯中的一种或多种。
在任意实施方式中，可选地，所述第一基膜和/或第二基膜经过氧化石墨烯分散液的浸润处理。
通过氧化石墨烯的分散液对基膜进行预处理，可以提高涂层与基膜的复合效率，减少粘结剂的使用，从而降低隔离膜电阻。
在任意实施方式中，可选地，所述第一基膜和/或第二基膜的厚 度为3-30μm，可选为5-25μm。
在任意实施方式中，可选地，所述隔离膜满足：ρ s≤10 7mΩ·cm，可选ρ s≤5×10 6mΩ·cm，其中ρ s表示表示隔离膜的离子电阻率。
当ρ s在上述范围内时，隔离膜的离子电阻率较小，有利于改善对应二次电池的动力学性能。
本申请的第二方面提供一种二次电池，包括本申请第一方面的隔离膜。
本申请的第三方面提供一种电池模块，包括本申请的第二方面的二次电池。
本申请的第四方面提供一种电池包，包括本申请的第二方面的二次电池或本申请第三方面的电池模块中的至少一种。
本申请的第五方面提供一种用电装置，包括本申请的第二方面的二次电池、本申请第三方面的电池模块或本申请的第四方面的电池包中的至少一种。
[有益效果]
本申请的隔离膜为三层复合结构，位于中间的涂层包括陶瓷颗粒、氧化石墨烯和粘结剂。陶瓷颗粒一方面可促进电解液对隔离膜的浸润，另一方面也可有效消耗产生的锂枝晶，避免锂枝晶穿透隔离膜，提升安全性能。涂层中的氧化石墨烯表面富含各种极性基团，一方面可进一步促进电解液对基膜的浸润，另一方面可通过以下作用而有助于减小电阻，从而改善对应电池的动力学性能：第一，氧化石墨烯本身可通过范德华力与基膜复合，减少粘结剂的使用；第二，氧化石墨烯能够提供大量供离子自由传输的通道，提升隔离膜的离子电导率。此外，涂层位于第一基膜和第二基膜中间，所述基膜本身可作为“阻挡层”存在，能够有效防止陶瓷颗粒与正负极极片直接接触，一方面有助于进一步提升对应二次电池的安全性能，另一方面也有助于避免很多副反应，提升对应电池使用时的稳定性，改善循环性能。
本申请的电池模块、电池包和用电装置包括本申请提供的二次电池，因而至少具有与所述二次电池相同的优势。
附图说明
图1为本申请隔离膜的示意图。
图2是本申请一实施方式的二次电池的示意图。
图3是图2所示的本申请一实施方式的二次电池的分解图。
图4是本申请一实施方式的电池模块的示意图。
图5是本申请一实施方式的电池包的示意图。
图6是图5所示的本申请一实施方式的电池包的分解图。
图7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；11第一基膜；12陶瓷粒子；13氧化石墨烯片；14第二基膜
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的隔离膜及使用其的二次电池、电池模块、电池包和用电装置的实施方式。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。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
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，则理解为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。
需要说明的是，在本申请中，关于石墨烯的术语可参照标准GB/T 30544.13-2018中的含义理解，相关参数也可参照该标准测量。例如，根据GB/T 30544.13-2018，术语“二维材料”是指由一层或几层构成，其中每一层内的原子与所在层内的邻近原子紧密成键结合，有一个维度(即其厚度)处于纳米或更小尺度，其余两个维度通常处于更大尺度的材料；术语“横向尺寸”是指二维材料薄片的横向大小。
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)。
发明人在实际工作中发现，现有技术为提高电解液对聚烯烃膜的浸润，通常会在聚烯烃膜表面施加陶瓷涂层。为提高陶瓷颗粒与基膜的粘结性能，需要使用大量的粘结剂，这会导致隔离膜电阻增大。
出人意料地，发明人在进行大量实验后发现，通过在两层基膜中间施加包含陶瓷颗粒、氧化石墨烯和粘结剂的涂层，既可促进电解液对隔离膜的浸润、有效避免锂枝晶穿透隔离膜，又可避免施加涂层或使用大量粘结剂而导致隔离膜电阻大幅增加，还可避免很多副反应的发生，提升对应电池运行稳定性，从而提升应用所述隔离膜的二次电池的安全性能、动力学性能和循环性能。
[隔离膜]
本申请的第一方面提供一种隔离膜，包括依次层叠设置的第一基膜；第二基膜；以及位于第一基膜和第二基膜之间的包含陶瓷颗粒、氧化石墨烯和粘结剂的涂层。
本申请的隔离膜为三层复合结构，位于中间的涂层包括陶瓷颗粒、氧化石墨烯和粘结剂。陶瓷颗粒一方面可促进电解液对隔离膜的浸润、提升隔离膜的耐热性及机械性能，另一方面也可有效消耗产生的锂枝晶，避免锂枝晶穿透隔离膜，提升安全性能。涂层中的氧化石墨烯表面富含各种极性基团，一方面可进一步促进电解液对基膜的浸润，另一方面可通过以下作用而有助于减小电阻，从而改善对应电池的动力学性能：第一，氧化石墨烯本身可通过范德华力与基膜复合，减少粘结剂的使用；第二，氧化石墨烯能够提供大量供离子自由传输的通道，提升隔离膜的离子电导率。此外，涂层位于第一基膜和第二基膜中间，所述基膜本身可作为“阻挡层”存在，能够有效防止陶瓷颗粒与正负极极片直接接触，一方面有助于进一步提升对应二次电池的安全性能，另一方面也有助于避免很多副反应，提升对应电池使用时的稳定性，改善循环性能。
在一些实施方式中，可选地，所述陶瓷颗粒与所述粘结剂的质量之比为1∶0.001-0.3，可选为1∶0.01-0.1。作为示例，所述比例可以为1∶0.001、1∶0.005、1∶0.006、1∶0.01、1∶0.013、1∶0.017、1∶ 0.02、1∶0.026、1∶0.033、1∶0.05、1∶0.06、1∶0.1或1∶0.3以及上述比例中的任意两者所组成的范围。
当陶瓷颗粒与粘结剂的质量之比在上述范围内时，有利于使涂层具备适当的粘结性，更好地避免陶瓷颗粒“掉粉”，充分发挥陶瓷颗粒改善隔离膜的润湿性能、消耗锂枝晶的作用，提升对应二次电池的安全性能。
在一些实施方式中，可选地，所述陶瓷颗粒与所述粘结剂的质量之和与所述氧化石墨烯的质量之比为2-11∶1，可选2-9∶1。作为示例，所述比例可以为2∶1、3∶1、3.1∶1、5∶1、5.1∶1、5.3∶1、5.5∶1、6.5∶1、8∶1、9∶1、10∶1或11∶1以及上述比例中的任意两者所组成的范围。
当陶瓷颗粒与粘结剂的质量之和与氧化石墨烯的质量之比处于上述范围内时，有利于在涂层具备适当的粘结性，从而充分发挥陶瓷颗粒改善隔离膜的润湿性能、消耗锂枝晶的作用的同时，发挥氧化石墨烯减少粘结剂使用和促进离子自由传输的功能，减少隔离膜电阻，改善对应二次电池的动力学性能。
在一些实施方式中，可选地，所述氧化石墨烯与陶瓷颗粒的质量之比为1∶1.5-11，可选为1∶3-5。作为示例，所述比例可以为1∶1.5、1∶1.95、1∶3、1∶5、1∶8、1∶8.95、1∶9、1∶10或1∶11以及上述比例中的任意两者所组成的范围。
氧化石墨烯表面富含含氧官能团，当氧化石墨烯与陶瓷颗粒的质量之比在上述范围内时，有利于促进氧化石墨烯表面的含氧官能团与陶瓷颗粒之间形成分子间作用力和氢键作用，提高陶瓷颗粒在隔离膜上的粘结性，进而提高涂料整体的粘结性，还有利于避免氧化石墨烯片堆叠堵塞隔离膜微孔。此外，当氧化石墨烯与陶瓷颗粒的质量之比在上述范围内时，也有利于改善涂层消耗锂枝晶的功能。
在一些实施方式中，可选地，基于所述涂层的总重量计，所述氧化石墨烯的含量为5-40％，可选为15-30％；
所述陶瓷颗粒的含量为25-95％，可选为70-85％；
所述粘结剂的含量为0.001-8％，可选为0.01％-0.5％。
在一些实施方式中，可选地，所述氧化石墨烯∶陶瓷颗粒∶粘结剂的质量比为0.09-1∶1∶0.001-0.3。作为示例，上述比例可以为0.1∶1∶0.001、0.2∶1∶0.001、0.2∶1∶0.01、0.2∶1∶0.1、0.2∶1∶0.3、0.3∶1∶0.3、0.5∶1∶0.2或1∶1∶0.3以及上述比例中的任意两者所组成的范围。
在一些实施方式中，可选地，所述氧化石墨烯为氧化石墨烯片，可选地，所述氧化石墨烯片的最大横向尺寸为0.01-10μm。
氧化石墨烯表面富含羟基、羧基、醛基等含氧官能团，因此能有效提升隔离膜的亲液性，使电解液能快速浸润隔离膜。此外，层叠的氧化石墨烯片创造了大量间隙使锂离子能在片层孔隙中自由传输，提高了隔离膜的离子电导率。另外，小片径的氧化石墨烯有利于防止石墨烯覆盖隔离膜上的微孔及因此导致隔离膜透气性下降，从而避免离子传输受阻和隔离膜阻抗大幅增加。
在一些实施方式中，可选地，所述陶瓷颗粒选自以下元素的氧化物、氮化物或含氧酸盐中的一种或多种：Si、Fe、Sn、Ti、Cu、Mg、Ge、Zn、Zr和B；
可选选自Si的氧化物、Si的氮化物、Fe的氧化物、Fe的氮化物、Fe的含氧酸盐、Sn的氧化物、Ti的氧化物、Ti的氮化物、Ti的含氧酸盐、Cu的氧化物、Cu的氮化物、Mg的氧化物、Ge的氧化物、Zn的氧化物、锆的氧化物、及氮化硼中的一种或多种；
更可选选自二氧化钛(TiO 2)、二氧化硅(SiO 2)、二氧化锡(SnO 2)、氧化锌(ZnO)、氧化锆(ZrO 2)、钛酸锂中的一种或多种。
在本申请中，第一基膜和第二基膜具有较强的疏水性，与强极性电解液的亲和性较差，这导致基膜无法吸收并保持电解液。本申请所述的陶瓷颗粒具备较强的亲水性，这有利于显著提高隔离膜的电解液浸润性。
此外，在锂金属电池数次充放电过程中，不可避免地会产生锂枝晶。如果不加控制，锂枝晶最终会接触并刺破隔离膜，导致正负极接触，从而引发安全问题。本申请所述陶瓷颗粒所包含的成分如二氧化硅能够发生嵌锂反应，及时消耗产生的锂枝晶，从而提升相应电池的 安全性能。
本申请所述陶瓷颗粒消耗锂枝晶的反应机理可分为合金化反应机制、插层反应机制和氧化还原机制：
1)合金化反应机制：金属氧化物与锂枝晶发生反应，伴随有金属单质生成，然后生成的金属单质发生进一步的合金化反应生成锂合金，反应方程式为：
A xO y+2yLi ++2ye -→xA+yLi 2O
Figure PCTCN2022105167-appb-000001
以二氧化锡为例，在放电过程中首先生成锡单质和Li 2O，然后锡单质和Li+反应生成Li 4.4Sn化合物。
2)插层反应机制：在充放电过程中Li +只能嵌入材料的层间结构的空隙中，其充放电过程的化学反应式为：
Figure PCTCN2022105167-appb-000002
插层反应机制的代表陶瓷材料主要是SiO 2、TiO 2、钛酸锂等。
3)转化反应机制：金属氧化物与Li +发生氧化还原反应生成金属单质和Li 2O，其化学反应式为：
A xO y+2yLi ++2ye -→xA+yLi 2O
在一些实施方式中，可选地，所述陶瓷颗粒的粒径为0.01-10μm，可选0.05-0.5μm。
当陶瓷颗粒粒径过大时，所制备的涂层的浆料粘度较大，且均匀性不易保证，难以涂覆至隔离膜上。此外，在涂覆隔离膜过程中易发生“掉粉”现象，粉体难以在隔离膜表面附着，导致涂覆效果不理想，难以达到预期。若颗粒粒径过小，则在涂覆陶瓷颗粒时，陶瓷颗粒会堵塞有机微孔材料表面的孔隙，降低了隔离膜的透气度，从而阻断了离子传输通道，使得电池的容量和循环寿命都有明显损失。
此外，当所述陶瓷颗粒的粒径在上述范围内时，陶瓷颗粒的引入，有利于提高隔离膜的孔隙率，加快Li +的扩散，提高隔离膜的离子电导率。
在一些实施方式中，可选地，所述粘结剂选自盐酸多巴胺、聚偏二氟乙烯、聚四氟乙烯、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、含氟丙烯酸酯、丁苯橡胶、聚丙烯酸钠、聚甲基丙烯酸、聚丙烯酰胺、聚乙烯醇、海藻酸钠、羧甲基壳聚糖、羧甲基纤维素钠中的一种或多种。
在一些实施方式中，可选地，所述涂层的厚度为0.1-10μm，可选1-6μm。
当涂层的厚度在上述范围内时，既可有效消耗锂枝晶，避免其穿透隔离膜，引发安全问题，又有利于避免涂层导致隔离膜电阻大幅增加。
在一些实施方式中，可选地，所述第一基膜和第二基膜各自独立地选自聚乙烯、聚丙烯、聚四氟乙烯、聚偏氟乙烯、聚氯乙烯、聚酰胺、以及聚酯中的一种或多种。
在一些实施方式中，可选地，所述第一基膜和/或第二基膜经过氧化石墨烯分散液的浸润处理。
通过氧化石墨烯的分散液对基膜进行预处理，可以使基膜表面包含许多极性基团，增加基膜的亲水性，从而提高电解液对基膜的浸润性。此外，基膜表面包含许多极性基团，有助于提高涂层与基膜的复合效率，减少粘结剂的使用，从而降低隔离膜电阻。
在一些实施方式中，可选地，所述第一基膜和第二基膜的重均分子量为100000-1000000。重均分子量可通过本领域通常使用的方法测量，例如可根据GB/T 21863-2008通过凝胶渗透色谱法测量。
在一些实施方式中，可选地，所述第一基膜和/或第二基膜的厚度为3-30μm，可选为5-25μm。
隔离膜的厚度过小，可能导致隔离膜的机械稳定性较差，并且难以充分发挥隔离膜间隔正负极极片的作用。隔离膜的厚度过大，可能导致隔离膜电阻增大，锂离子更难穿过隔离膜传输，导致电池性能下降。
在一些实施方式中，可选地，所述隔离膜满足：ρ s≤10 7mΩ·cm，可选ρ s≤5×10 6mΩ·cm，其中ρ s表示隔离膜的离子电阻率。
当ρ s在上述范围内时，隔离膜的离子电阻率较小，有利于改善对 应二次电池的动力学性能。
在一些实施方式中，本申请还提供一种制备本申请所述隔离膜的方法，至少包括以下步骤：
步骤1：将氧化石墨烯、陶瓷颗粒和粘结剂按照0.09-1∶1∶0.001-0.3的质量之比在适量的溶剂中充分混合，得到混合浆料；
步骤2：将步骤1所得混合浆料涂覆在第一基膜和第二基膜的一个表面上；和
步骤3：将步骤2所得第一基膜和第二基膜沿涂层侧叠合，经热压、干燥除去溶剂。
在一些实施方式中，可选地，步骤1中所述溶剂为水，N-N二甲基甲酰胺(DMF)，N-甲基吡咯烷酮(NMP)等。
在一些实施方式中，可选地，步骤1中所述氧化石墨烯为氧化石墨烯的分散液。
在一些实施方式中，可选地，所述氧化石墨烯的分散液的固含量为0.1-5％，可选为0.3-3％。
在一些实施方式中，可选地，所述氧化石墨烯分散液可通过将氧化石墨烯加入到溶剂中，然后使用超声分散均匀而获得。
在一些实施方式中，可选地，所述氧化石墨烯的分散液中的溶剂可选自水、乙醇、异丙醇、正丁醇、异丁醇中的一种或多种。
在一些实施方式中，可选地，在进行步骤2之前，使用氧化石墨烯的分散液对所述第一基膜和第二基膜进行预处理。
在一些实施方式中，可选地，对基膜进行预处理的分散液为氧化石墨烯的水分散液或氧化石墨烯的异丙醇分散液。
在一些实施方式中，可选地，所述预处理是指将基膜完全浸入到氧化石墨烯的分散液中，并保持15-120s，可选30-90s，然后取出干燥。
在一些实施方式中，可选地，步骤2中的涂覆可通过本领域通常使用的涂覆方法进行，例如刮刀涂布、辊涂或挤出机涂布等。
在一些实施方式中，可选地，步骤3所述热压在90-150℃，可选120-140℃的温度下进行。
在一些实施方式中，可选地，步骤3所得隔离膜上涂层的涂覆密度为1.0-6.0g/m 2，可选为1.5-4.5g/m 2。
在一些实施方式中，可选地，在本申请所述隔离膜中，氧化石墨烯、陶瓷颗粒与粘合剂的质量比为0.09-1∶1∶0.001-0.3。作为示例，所述比例可为0.2∶1∶0.02、0.33∶1∶0.033、1.125∶1∶0.0125、0.1∶1∶0.001、0.2∶1∶0.01、0.2∶1∶0.06、0.2∶1∶0.02、0.2∶1∶0.001、0.2∶1∶0.006、0.5∶1∶0.03、0.1∶1∶0.006或0.09∶1∶0.004以及上述比例中的任意两者所组成的范围。
[二次电池]
本申请的第二方面提供一种二次电池，其包括本申请第一方面所述的隔离膜。通常，除隔离膜以外，二次电池还包括正极极片、负极极片和电解液。
特别地，本申请所述隔离膜也可用于锂金属电池，代替传统隔离膜使用。所述锂金属电池的负极可以为锂金属或锂合金，或者无负极。相应的正极材料如下文所述。若为无负极锂金属电池，则正极材料需提供锂源。
二次电池的制备可通过本领域通常使用的方法进行，例如，可将正极极片、负极极片和隔离膜通过卷绕工艺或叠片工艺制成电极组件，然后向电极组件中注入电解液并密封而制得二次电池。
下面分别对二次电池的上述部件进行说明。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面上的正极膜层。作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
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层(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。
在本申请中，正极材料是能可逆地嵌入与脱嵌Li +的化合物。
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，可以列举出Li xMO 2或Li yM 2O 4(其中M为过渡金属，0≤x≤1，0≤y≤2)表示的含锂复合氧化物、尖晶石状的氧化物、层状结构的金属硫族化物、橄榄石结构等。例如，可以列举出LiCoO 2等锂钴氧化物、LiMn 2O 4等锂锰氧化物、LiNiO 2等锂镍氧化物、Li 4/3Ti 5/3O 4等锂钛氧化物、锂锰镍复合氧化物、锂锰镍钴复合氧化物；具有LiMPO 4(M＝Fe、Mn、Ni)等橄榄石型结晶结构的材料等。
在一些实施方式中，可选地，正极活性材料是层状结构或尖晶石状结构的含锂复合氧化物，例如以LiCoO 2、LiMn 2O 4、LiNiO 2、LiNi 1/2Mn 1/2O 2等为代表的锂锰镍钴复合氧化物，以LiNi 1/3Mn 1/3Co 1/3O 2、LiNi 0.6Mn 0.2Co 0.2O 2等为代表的锂锰镍钴复合氧化物，或LiNi 1-x-y-zCo xAl yMg zO 2(式中，0≤x≤1、0≤y≤0.1、0≤z≤0.1、0≤1-x-y-z≤1)等含锂复合氧化物。此外，上述含锂复合氧化物中的构成元素的一部分，被Ge、Ti、Zr、Mg、Al、Mo、Sn等添加元素所取代的含锂复合氧化物等也包含在本申请的范围内。
除上述正极活性材料以外，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。例如，通过同时使用层状结构的含锂复合氧化物与尖晶石结构的含锂复合氧化物，可以谋求兼顾大容量化及安全性的提升。
在一些实施方式中，可选地，所述正极活性材料占所述正极膜片的质量百分比为75％至99％，可选80％至97％。
在一些实施方式中，正极膜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，可选地，所述导电剂占正极膜层总重量的0.05-5％，可选为0.5-3％。
在一些实施方式中，正极膜层还可选地包括粘结剂，例如聚偏二氟乙烯、聚四氟乙烯、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、聚环氧乙烷等电池领域中通常使用的粘结剂。
在一些实施方式中，可选地，所述粘结剂占正极膜层总重量的0.1-3.5％，可选为0.5-2.5％。
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]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层。作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
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。
在本申请中，负极材料是能够嵌入-脱嵌锂金属、锂的化合物。
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，可使用铝、硅、锡等的合金或氧化物、碳材料等各种材料作为负极活性材料。可选地，氧化物可以列举出二氧化钛等，碳材料可以列举出石墨、热解碳类、焦炭类、玻璃状碳类、 有机高分子化合物的烧成体、中间相碳微珠等。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，可选地，所述负极活性材料占所述正极膜片的质量百分比为75％至99％，可选80％至97％。
在一些实施方式中，负极膜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。
在一些实施方式中，可选地，所述导电剂占负极膜层总重量的0.05-5％，可选为0.5-3％。
在一些实施方式中，负极膜层还可选地包括粘结剂，例如聚偏二氟乙烯、聚四氟乙烯、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、聚环氧乙烷等电池领域中通常使用的粘结剂。
在一些实施方式中，可选地，所述粘结剂占负极膜层总重量的0.1-3.5％，可选为0.5-2.5％。
在一些实施方式中，负极膜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，可选地，所述增稠剂占所述负极膜片的质量百分比为0.04％至5％，可选为0.5％至3％。
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，使用非水溶剂(有机溶剂)作为非水电解液。非水溶剂包括碳酸酯类、醚类等。
在一些实施方式中，碳酸酯类包括环状碳酸酯和链状碳酸酯。环状碳酸酯可以列举出碳酸亚乙酯、碳酸亚丙酯、碳酸亚丁酯、γ-丁内酯、硫类酯(乙二醇硫化物)等。链状碳酸酯可以列举出碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯等为代表的低粘度的极性链状碳酸酯、脂肪族支链型碳酸酯类化合物。环状碳酸酯(特别是碳酸乙烯酯)与链状碳酸酯的混合溶剂是特别优选的。
醚类可以列举出二甲醚四甘醇(TEGDME)、乙二醇二甲醚(DME)、1，3-二氧戊烷(DOL)等。
另外，除上述非水溶剂外，还可以采用丙酸甲酯等链状烷基酯类、磷酸三甲酯等链状磷酸三酯；3-甲氧基丙腈等腈类溶剂；以树枝状化合物为代表的具有醚键的支链型化合物等非水溶剂(有机溶剂)。
另外，也可采用氟类溶剂。作为氟类溶剂，例如，可以列举出H(CF 2) 2OCH 3、C 4F 9OCH 3、H(CF 2) 2OCH 2CH 3、H(CF 2) 2OCH 2CF 3、H(CF 2) 2CH 2O(CF 2) 2H等，或CF 3CHFCF 2OCH 3、CF 3CHFCF 2OCH 2CH 3等直链结构的(全氟烷基)烷基醚，例如2-三氟甲基六氟丙基甲醚、2-三氟甲基六氟丙基乙醚、2-三氟甲基六氟丙基丙醚、3-三氟甲基八氟丁基甲醚、3-三氟甲基八氟丁基乙醚、3-三氟甲基八氟丁基丙醚、4-三氟甲基十氟戊基甲醚、4-三氟甲基十氟戊基乙醚、4-三氟甲基十氟戊基丙醚、5-三氟甲基十二氟己基甲醚、5-三氟甲基十二氟己基乙醚、5-三氟甲基十二氟己基丙醚、6-三氟甲基十四氟庚基甲醚、6-三氟甲基十四氟庚基乙醚、6-三氟甲基十四氟庚基丙醚、7-三氟甲基十六氟辛基甲醚、7-三氟甲基十六氟辛基乙醚、7-三氟甲基十六氟辛基丙醚等。
另外，也可使用异(全氟烷基)烷基醚与直链结构的(全氟烷基)烷基醚的混合物。
作为非水电解液中使用的电解质盐，优选锂的高氯酸盐、有机硼锂盐、含氟化合物的锂盐、锂酰亚胺盐等锂盐。
作为这样的电解质盐的例子，例如，可以列举出LiClO 4、LiPF 6、LiBF 4、LiAsF 6、LiSbF 6、LiCF 3SO 3、LiCF 3CO 2、LiC 2F 4(SO 3) 2、LiN(C 2F 5SO 2) 2、LiC(CF 3SO 2) 3、LiC nF 2n+1SO 3(n≥2)、LiN(R fOSO 2) 2(式中，R f为氟代烷基)等。在这些锂盐中，含氟有机锂盐是特别优选的。含氟有机锂盐，由于阴离子极性大且易分离成离子，在非水电解液中易溶解。
电解质锂盐在非水电解液中的浓度，例如为0.3mol/L(摩尔/升)以上，更可选0.7mol/L以上；可选1.7mol/L以下，更可选1.2mol/L以下。当电解质锂盐的浓度过低时，离子传导度过小，过高时，担心未能溶解完全的电解质盐析出。
在一些实施方式中，所述电解液还可选地包括添加剂，本申请不作特别限定。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。
[电池模块、电池包和用电装置]
本申请的第三方面提供一种电池模块，包括本申请的第二方面的二次电池。电池模块的制备可采用本领域通常使用的方法。
本申请的第四方面提供一种电池包，包括本申请第二方面的二次电池或本申请第三方面的电池模块中的至少一种。电池包的制备可采用本领域通常使用的方法。
本申请的第五方面提供一种用电装置，包括选自本申请的第二方面的二次电池、本申请的第三方面的电池模块或本申请的第四方面的电池包中的至少一种。
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。
在一些实施方式中，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。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。 软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
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2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3，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4是作为一个示例的电池模块3。参照图4，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5和图6是作为一个示例的电池包1。参照图5和图6，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、或电池包中的至少一种。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。所述用电装置可以包括移动设备(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7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。
一、隔离膜
实施例1
步骤1：聚丙烯膜的亲水化改性
在聚丙烯膜(PP膜)表面涂覆纳米级别亲水的氧化石墨烯层
配置0.02wt％的氧化石墨烯(GO，采购自南京先丰纳米科技有限公司)的异丙醇(IPA)分散液。准备体积分数比为异丙醇∶水的体积比为20∶1的IPA水溶液，将0.02g GO加入到100g所述IPA水溶液中，超声震荡30min后得到GO的异丙醇(IPA)分散液。然后将7μm PP膜完全浸入分散液中，持续30s后取出干燥，重复此流 程5次，即可得到表面亲水的PP膜。
步骤2：混合浆料的制备
将固含量为1wt％GO的水分散液(配制方法同步骤1，仅使用水作为溶剂，以包含水的湿重计，下同)、SiO 2(400nm，以干重计，下同)、混合粘结剂(以混合粘结剂的干重计，下同)按100∶5∶0.1的质量比混合，在800rpm下搅拌30min使浆料混合均匀备用。
其中，所述混合粘结剂的配置方法为：将0.75g盐酸多巴胺、0.2g羧甲基纤维素钠(CMC)、10ml的去离子水和乙醇(1∶1，v∶v)的混合溶液(水基溶剂)混合均匀。然后使用浓度为1mol/L的NaOH水溶液调节pH至8.5，得到混合粘结剂。
步骤3：隔离膜的涂覆
用刮刀将步骤2所得浆料均匀涂覆在GO修饰过的PP膜一侧上，以制备SiO 2/GO-PP膜。
双层PP膜复合
按照上述步骤1-3制备另一片SiO 2/GO-PP膜。然后将两片SiO 2/GO-PP膜的涂层侧相对叠合，然后在150℃下热压复合，然后置于真空干燥箱中在60℃下烘干过夜至彻底去除溶剂，即可得到PP-SiO 2/GO-PP三层结构的复合隔离膜，其中，陶瓷层的厚度为3μm，总厚度为17μm。
实施例2
除步骤2中二氧化硅粒径改为700nm外，实施例2的其他步骤与实施例1相同。
实施例3
除步骤2中二氧化硅粒径改为200nm外，实施例3的其他步骤与实施例1相同。
实施例4
除步骤2中陶瓷颗粒由二氧化硅改为三氧化二铁(粒径约100nm)外，实施例4的其他步骤与实施例1相同。
三氧化二铁能与锂枝晶进行合金化反应，其比容量高，稳定性好，离子电导率低，有利于锂枝晶的消耗，同时降低了隔离膜带来的内阻。
实施例5
除步骤2中陶瓷颗粒由二氧化硅改为二氧化锡(粒径约100nm)外，实施例5的其他步骤与实施例1相同。
实施例6
除步骤2中陶瓷粒子由二氧化硅改为二氧化钛(粒径约100nm，锐钛矿型)外，实施例6的其他步骤与实施例1相同。
二氧化钛能与锂枝晶发生插层反应，生成钛酸锂。其理论容量高，结构稳定，在嵌锂后氧化物结构不会发生太大变化。
实施例7
除步骤2中陶瓷粒子由二氧化硅改为氧化铜(CuO，粒径约150nm)外，实施例7的其他步骤与实施例1相同。
氧化铜与锂发生转换反应，产生非晶态的Li 2O和纳米级金属铜颗粒，产生的纳米铜颗粒还能与Li 2O进一步反应生成氧化物，使其具有较高的比容量和良好的循环性能。
实施例8
除步骤1中不使用氧化石墨烯的分散液对聚丙烯膜进行亲水化改性以外，实施例8的其他条件与实施例1相同。
实施例9-14
将步骤2中的1wt％GO的水分散液(配制方法同步骤1，仅使用水作为溶剂)、SiO 2(400nm)、混合粘合剂的质量配比依次调整为
实施例9：100∶3∶0.1；
实施例10：100∶8∶0.1；
实施例11：100∶10∶0.1；
实施例12：100∶5∶0.05；
实施例13：100∶5∶0.3；
实施例14：100∶5∶0.5。
其余与实施例1相同。
实施例15-17
除步骤3中涂层厚度改为4μm、5μm、6μm外，其余步骤与实施例1相同。
实施例18-20
除陶瓷颗粒与混合粘合剂的质量比分别为1∶0.001、1∶0.3和1∶0.006以外，其余与实施例1相同。
实施例21-24
除陶瓷颗粒与混合粘合剂的质量之和与氧化石墨烯的质量之比分别为2∶1、3∶1、9∶1和11∶1以外，其余与实施例1相同。
实施例25
除步骤2中陶瓷粒子由二氧化硅改为氧化铝(粒径约400nm)以外，实施例25的条件与实施例1相同。
对比例1
除步骤2中不使用氧化石墨烯以外，其余步骤与实施例1相同。
实施例1-25及对比例的测试结果参见表1。
二、二次电池
正极极片的制备
将正极活性材料磷酸铁锂(以LiFePO 4计)、导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)以96.5∶2∶1.5的质量比混合，溶解在溶剂N-甲基吡咯烷酮(即NMP)中，并充分搅拌混合均匀，得到正极浆料。然后将正极浆料均匀涂覆于铝箔上，经烘干、冷压、分切，得到正极极片。所得极片的涂覆面密度为19.5mg/cm 2，压实密度为2.4g/cm 3。
负极极片的制备
将石墨、导电剂乙炔黑、粘结剂PVDF、增稠剂羧甲基纤维素钠(CMC)按照质量比96.5重量份∶0.7重量份∶1.8重量份∶1重量份溶于溶剂去离子水中，并充分搅拌混合均匀，得到负极浆料。将负极浆料均匀涂覆在负极集流体铜箔上，经过烘干、冷压、分切得到负极极片。所得极片的涂覆面密度为9.8mg/cm 2，压实密度为1.65g/cm 3。
电解液的制备
将有机溶剂碳酸亚乙酯(EC)/碳酸甲乙酯(EMC)按照重量比50/50混合均匀，加入LiPF 6溶解于上述有机溶剂中，搅拌均匀，使 LiPF 6的浓度为1.1mol/L，得到电解液。
隔离膜
使用本申请实施例和对比例制得的隔离膜作为二次电池的隔离膜。
二次电池
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。所得二次电池的尺寸为60×130×4mm。
相关参数测试方法
1.隔离膜性能测试
1)隔离膜的抗拉强度(Transverse Direction，TD)测试
依据ASTM D882-09规范测试。将测试的隔离膜裁切成宽度10mm且长度≥150mm的大小，利用万能拉力机以500mm/min的速率进行拉伸，取得试样断裂时的最大荷重值后将其除以隔离膜的截面积(试样宽度×试样厚度)，计算出隔离膜的拉伸强度。
2)隔离膜的剥离力测试
利用滚压机以固定应力(2kg、300mm/min)将20mm宽的标准胶带(31B，购自于日东)贴于隔离膜的陶瓷涂层面上，利用拉力试验机以300mm/min的速度进行180度剥离测试，在50mm至120mm的测试距离中取得50点剥离力的数值并算出平均值。
3)隔离膜的润湿性测试
将测试的隔离膜裁切成50mm×50mm的大小，将1ml的标准电解液(LiPF 6溶于碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)以及碳酸二甲酯(DMC)的重量比为1∶1∶1的混合溶剂中形成的电解液，LiPF 6浓度为1mol/l)滴在样品上，以接触角仪观察液滴与隔离膜所成夹角。
4)隔离膜的吸液速率测试
将测试的隔离膜裁切成200mm×15mm的大小，在密闭空间内将样品垂直悬挂在电解液的溶剂(EC∶DMC∶DEC的重量比为1∶1∶1的混合溶剂)上方，使隔离膜下端恰好与溶剂表面接触，15分钟后 记录隔离膜毛细吸液的高度并计算出吸液速率(吸液高度/吸液时间)。
2.陶瓷颗粒粒径测试
粒度分析Dv50：占总体积50％的颗粒直径大于此值，另有占总体积50％的颗粒直径小于此值，Dv50表示粉体的中值粒度；
颗粒在激光束的照射下，其散射光的角度与颗粒的直径成反比关系而散射光强随角度的增加呈对数规律衰减，散射光的能量分布与颗粒直径的分布直接相关，通过接受和测量散向光的能量分布就可以得出颗粒的粒度分布特征。参考标准GB/T19077.1-2009粒度分布激光衍射法。
3.涂层的涂布面密度(ρ)测试
涂布面密度(ρ)＝涂布重量(m)/涂布面积(A)。
称取涂布前隔离膜重量(m 0)与涂布后隔离膜重量(m 1)，二者之差即为涂布重量。同时测量隔离膜已涂布面积，即可得到涂布面密度。
4.涂层所导致的隔离膜离子电阻率(ρ s)测试
测试方法：采用电化学阻抗谱研究电池中隔离膜对锂离子透过性的影响。使用交流法测量的电化学阻抗谱图中，可以得到电池的内阻(和隔离膜的电阻有关)，因此可以用此方法得到电池的电荷转移电阻。采用IVIUM电化学工作站测试，频率为0.1Hz-100kHz。
根据电阻定律，使用限域性对称电池EIS法测得不同隔离膜层数(n)的Rs作为隔离膜电阻，以Rs和n作图得到斜率k，在已知有效面积S和隔离膜厚度的条件下计算隔离膜的离子电阻率。
实际测试得到的通常是电池的离子电阻，即体积电阻。而试验测试得到的离子电阻(R b)是隔离膜电阻(R s)与电池中电解液的电阻(R e)之和，如下所示
R b＝R s+R e
为便于计算，可忽略Re的影响，近似地认为Rs＝Rb，再根据式下式即可求得隔离膜的电阻率(ρ s)
Figure PCTCN2022105167-appb-000003
式中ρ s是隔离膜的电阻率，S为隔离膜的有效面积，d为隔离膜的平均厚度。
5.固含量测试
固含量可参照GB/T 1725-2007《色漆、清漆和塑料不挥发物含量的测定》进行测试。
6.二次电池的性能测试
库伦效率测试：
1)充电条件：在室温下利用定电流-定电压模式(CC-CV mode)对电池进行充电。先在定电流模式下以0.1C的固定电流充电至电压升为3.65V，接着切换为定电压模式，直至电流为0.02C，使电池完全充饱。
2)放电条件：以不同的放电率(C-rate：0.1C/1C/3C)进行定电流模式放电至2.5V，并循环200圈。
3)计算并记录200圈后不同放电倍率下的库伦效率(放电容量/充电容量*100％)，得到表1。
功率测试：
1)充电条件：在室温下利用定电流-定电压模式(CC-CV mode)对电池进行充电。先在定电流模式下以0.1C的固定电流充电至电压升为3.65V，接着切换为定电压模式，直至电流为0.02C，使电池完全充饱；
2)放电条件：以放电率为0.1C进行定电流模式放电至2.5V；
3)计算并记录充放电过程中的平均功率(电压*电流)。
Figure PCTCN2022105167-appb-000004
Figure PCTCN2022105167-appb-000005
Figure PCTCN2022105167-appb-000006
根据表1结果可知，1)使用了氧化石墨烯分散液预处理的隔离膜能更有效地与陶瓷-氧化石墨烯涂料接触，有助于更好地改善隔离膜的综合性能；2)相对于氧化铝，使用本申请其他陶瓷颗粒能更好提升隔离膜的机械性能与润湿性；3)氧化石墨烯有助于提高隔离膜的粘结性、润湿性和离子传导能力；4)通过调整氧化石墨烯、粘结剂和陶瓷颗粒的配比可进一步改善隔离膜的综合性能。
此外，根据表1结果可知，使用氧化石墨烯-陶瓷粒子混合涂料涂覆的隔离膜所对应的二次电池具备较高的库伦效率，低倍率下循环200圈后依然能保持在99％以上；高倍率下的库伦效率也较高，表明二次电池具备良好的循环性能和更长的使用寿命。同时，相对于对比例1，使用本申请隔离膜的二次电池具备更高的功率，表明其动力学性能较好。另外，由于隔离膜良好的耐枝晶能力，循环过程产生的锂枝晶能被及时消耗，因而对应二次电池均具有良好的安全性能。
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. 一种隔离膜，包括依次层叠设置的第一基膜；第二基膜；以及位于第一基膜和第二基膜之间的包含陶瓷颗粒、氧化石墨烯和粘结剂的涂层。
  2. 根据权利要求1所述的隔离膜，其中所述陶瓷颗粒与所述粘结剂的质量之比为1∶0.001-0.3，可选为1∶0.01-0.1。
  3. 根据权利要求1或2所述的隔离膜，其中所述陶瓷颗粒与所述粘结剂的质量之和与所述氧化石墨烯的质量之比为2-11∶1，可选2-9∶1。
  4. 根据权利要求1至3中任一项所述的隔离膜，其中所述氧化石墨烯与陶瓷颗粒的质量之比为1∶1.5-11，可选为1∶3-5。
  5. 根据权利要求1至4中任一项所述的隔离膜，其中
    所述氧化石墨烯为氧化石墨烯片，可选地，所述氧化石墨烯片的最大横向尺寸为0.01-10μm。
  6. 根据权利要求1至5中任一项所述的隔离膜，其中
    所述陶瓷颗粒选自以下元素的氧化物、氮化物或含氧酸盐中的一种或多种：Si、Fe、Sn、Ti、Cu、Mg、Ge、Zn、Zr和B；
    可选选自Si的氧化物、Si的氮化物、Fe的氧化物、Fe的氮化物、Fe的含氧酸盐、Sn的氧化物、Ti的氧化物、Ti的氮化物、Ti的含氧酸盐、Cu的氧化物、Cu的氮化物、Mg的氧化物、Ge的氧化物、Zn的氧化物、锆的氧化物、及氮化硼中的一种或多种；
    更可选选自二氧化钛、二氧化硅、二氧化锡、氧化锌、氧化锆、钛酸锂中的一种或多种。
  7. 根据权利要求1至6中任一项所述的隔离膜，其中所述陶瓷颗粒的粒径为0.01-10μm，可选0.05-0.5μm。
  8. 根据权利要求1至7中任一项所述的隔离膜，其中所述粘结剂选自盐酸多巴胺、聚偏二氟乙烯、聚四氟乙烯、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、含氟丙烯酸酯、丁苯橡胶、聚丙烯酸钠、聚甲基丙烯酸、聚丙烯酰胺、聚乙烯醇、海藻酸钠、羧甲基壳聚糖、羧甲基纤维素钠中的一种或多种。
  9. 根据权利要求1至8中任一项所述的隔离膜，其中所述涂层的厚度为0.1-10μm，可选1-6μm。
  10. 根据权利要求1至9中任一项所述的隔离膜，其中所述第一基膜和第二基膜各自独立地选自聚乙烯、聚丙烯、聚四氟乙烯、聚偏氟乙烯、聚氯乙烯、聚酰胺、以及聚酯中的一种或多种。
  11. 根据权利要求1至10中任一项所述的隔离膜，其中所述第一基膜和/或第二基膜经过氧化石墨烯分散液的浸润处理。
  12. 根据权利要求1至11中任一项所述的隔离膜，其中所述第一基膜和/或第二基膜的厚度为3-30μm，可选为5-25μm。
  13. 根据权利要求1至12中任一项所述的隔离膜，其中所述隔离膜满足：ρ s≤10 7mΩ·cm，可选ρ s≤5×10 6mΩ·cm，其中ρ s表示隔离膜的离子电阻率。
  14. 一种二次电池，包括权利要求1至13中任一项所述的隔离膜。
  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14所述的二次电池或权利要求15所述的电池模块中的至少一种。
  17. 一种用电装置，包括选自权利要求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所述的电池包中的至少一种。
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