WO2019218888A1 - 一种电池、电池隔膜及其制备方法 - Google Patents

一种电池、电池隔膜及其制备方法 Download PDF

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Publication number
WO2019218888A1
WO2019218888A1 PCT/CN2019/085704 CN2019085704W WO2019218888A1 WO 2019218888 A1 WO2019218888 A1 WO 2019218888A1 CN 2019085704 W CN2019085704 W CN 2019085704W WO 2019218888 A1 WO2019218888 A1 WO 2019218888A1
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Prior art keywords
battery
battery separator
nanowires
dispersion
dip coating
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PCT/CN2019/085704
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English (en)
French (fr)
Inventor
王艳杰
杨雪梅
谭彬
伍志杰
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深圳市星源材质科技股份有限公司
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Priority to EP19802545.4A priority Critical patent/EP3796418A4/en
Priority to JP2020566870A priority patent/JP2021514111A/ja
Priority to KR1020207024767A priority patent/KR102475114B1/ko
Priority to US16/975,206 priority patent/US20200411829A1/en
Publication of WO2019218888A1 publication Critical patent/WO2019218888A1/zh

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403Manufacturing processes of separators, membranes or diaphragms
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/411Organic material
    • H01M50/414Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417Polyolefins
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/411Organic material
    • H01M50/429Natural polymers
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/431Inorganic material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/431Inorganic material
    • H01M50/434Ceramics
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/44Fibrous material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/449Separators, membranes or diaphragms characterised by the material having a layered structure
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/449Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/449Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/454Separators, membranes or diaphragms characterised by the material having a layered structure comprising a non-fibrous layer and a fibrous layer superimposed on one another
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/463Separators, membranes or diaphragms characterised by their shape
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491Porosity
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/60Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
    • H01M50/609Arrangements or processes for filling with liquid, e.g. electrolytes
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present disclosure relates to the field of batteries, and in particular to a battery, a battery separator, and a method of fabricating the same.
  • a lithium ion battery is a secondary battery that is currently widely used.
  • Lithium-ion batteries mainly rely on lithium ions to move between the positive and negative electrodes to work.
  • Li + is intercalated and deintercalated between the two electrodes.
  • the electrolyte is inserted into the negative electrode, the negative electrode is in a lithium-rich state, and the more lithium ions are embedded in the negative electrode, the higher the charging capacity); when discharged, the lithium ions embedded in the negative carbon layer are released. And returning to the positive electrode through electrolyte movement, the more lithium ions return to the positive electrode, the higher the discharge capacity.
  • Lithium-ion batteries have the advantages of high operating voltage, large specific energy, long cycle life, low self-discharge, no pollution, no memory effect, etc., so they are widely used in mobile phones, portable devices, automobiles, aviation, scientific research, Modern electronics such as entertainment and military, and gradually replace traditional batteries.
  • Lithium-ion batteries are mainly composed of four materials, including positive electrode materials, negative electrode materials, separators, and electrolytes. As one of its important components, the diaphragm plays a very important role in its performance.
  • a battery separator is a layer of separator material between the positive and negative electrodes of a battery, usually referred to as a battery separator. The main function of the battery separator is to isolate the positive and negative electrodes and prevent electrons in the battery from passing freely, while allowing ions in the electrolyte to pass freely between the positive and negative electrodes.
  • the ion conductivity of the battery separator is directly related to the overall performance of the battery.
  • the function of isolating the positive and negative poles can limit the increase of current in the case of overcharging or temperature increase, prevent the battery short circuit from causing explosion, and have microporous self-closing protection function to protect the battery user and equipment.
  • the role. Polyolefin materials are widely used as microporous separators because of their low cost, good mechanical strength and chemical stability, good overall performance, and low cost. However, due to its lack of thermal stability, its further application in batteries has been limited.
  • the present disclosure provides a battery separator.
  • the battery separator has a composite structure composed of a first member and a second member.
  • the diaphragm includes:
  • the first component is fabricated from a modified material that is provided to improve the thermal stability of the battery separator, the first component being a stack of nanowires distributed in layers;
  • the second component is fabricated from a substrate material that is provided as a body of the battery separator, the first component being supported by the second component and supported by the second component.
  • the thickness of the first element is on the order of microns and/or sub-micron.
  • the first element has a thickness of 0.01 to 1 ⁇ m.
  • the nanowires have an aspect ratio greater than 50.
  • the nanowires have a diameter of from 1 to 100 nm and a length of from 0.1 to 100 ⁇ m.
  • the modifying material comprises one of carbon nanotubes, nanosilver wires, boron carbide nanowires, nanocellulose, copper hydroxide nanowires, silicon oxide nanowires, hydroxyapatite nanowireskind or more.
  • the substrate material is an organic polymeric material.
  • the organic polymeric material includes a polyolefin.
  • the polyolefin comprises polyethylene
  • the first element has a porous structure.
  • the present disclosure also provides a method of making the above battery separator.
  • a method of preparing a battery separator is used to fabricate a battery separator having the following structure.
  • the battery separator includes a first member and a second member, wherein the first member is supported in a layered manner on the second member, and the first member is composed of nanowires;
  • Preparation methods include:
  • the dispersion is transferred to the surface of the second member, and the dispersant in the dispersion on the surface of the second member is removed to load the nanowires in a layered manner on the surface of the second member.
  • the dispersing agent includes one or more of water, ethanol, acetone, N-methylpyrrolidone, and the dispersion further contains an adhesive.
  • the adhesive includes one or more of polyvinyl alcohol, polyacrylonitrile, polyacrylic acid, styrene butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride, polyvinyl pyrrolidone, and polyimide.
  • polyvinyl alcohol polyacrylonitrile
  • polyacrylic acid polyacrylic acid
  • styrene butadiene rubber carboxymethyl cellulose
  • polyvinylidene fluoride polyvinyl pyrrolidone
  • polyimide polyimide
  • an adjuvant is also included in the dispersion.
  • the nanowires in the dispersion have a mass concentration of 0.01 to 50% and the adhesive has a mass concentration of 0.01 to 49%.
  • the dispersion is transferred to the surface of the two components by coating.
  • the manner of coating includes spin coating or knife coating or dip coating.
  • the dispersion is transferred to the surface of the second component by dip coating, and the dip coating method includes:
  • the second member is immersed in the dispersion at a first given speed and detached from the dispersion at a second given speed under tension by stretching.
  • the second element is tensioned by a tensioning system consisting of a plurality of rollers, the tensioning system having at least one dip coating roller for immersing the second element in the dispersion, dip coating Part or all of the roller is immersed in the dispersion.
  • the dip coating roller has a hollow cavity
  • the dip coating roller has a vent passage that communicates with the hollow cavity and extends to the surface, and the second component contacts the dip coating roller in a face-to-face manner
  • the surface, the cavity has a given degree of vacuum.
  • the degree of vacuum is from 0.01 to 0.1 MPa.
  • the present disclosure also provides a battery having the battery separator as described above.
  • the battery separator provided by the present disclosure has a composite structure which is an innovation of the existing battery separator and improves its thermal stability by using a modified material. Further, the use of the modified material in the form of a nanowire can avoid the problem of an increase in the thickness and weight of the separator due to the introduction of the modified material, thereby achieving the effects of thermal stability, thickness and weight increase of the battery separator.
  • FIG. 1 is a schematic structural view of a first battery separator according to an embodiment of the present disclosure
  • FIG. 2 is a schematic structural view of a second battery separator according to an embodiment of the present disclosure
  • FIG. 3 is a schematic structural view of a film forming apparatus for fabricating a second battery separator according to an embodiment of the present disclosure
  • Figure 4 is a schematic view showing the structure of the first viewing angle of the dip coating roller in the film forming apparatus of Figure 3;
  • Figure 5 is a schematic view showing the structure of a second viewing angle of the dip coating roller in the film forming apparatus of Figure 3;
  • Fig. 6 is a cross-sectional view showing the cross-sectional structure of the dip coating roller in the film forming apparatus of Fig. 3 taken along the axial direction.
  • Icons 100 - first element; 200 - second element; 300 - porous structure; 401 - storage slot; 402 - tensioning system; 403 - dip coating roller; 4031 - hollow cavity; 4032 - venting channel; Two components.
  • the orientation or positional relationship of the indications is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship that is conventionally placed when the disclosed product is used, for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying
  • the device or component referred to must have a particular orientation, is constructed and operated in a particular orientation, and thus is not to be construed as limiting the disclosure.
  • the terms “first”, “second”, “third”, and the like are used merely to distinguish a description, and are not to be construed as indicating or implying a relative importance.
  • the first feature "on” or “under” the second feature may include direct contact of the first and second features, and may also include first and second features, unless otherwise specifically defined and defined. It is not in direct contact but through additional features between them.
  • the first feature “above”, “above” and “above” the second feature includes the first feature directly above and above the second feature, or merely indicating that the first feature level is higher than the second feature.
  • the first feature “below”, “below” and “below” the second feature includes the first feature directly below and below the second feature, or merely the first feature level being less than the second feature.
  • battery separators particularly polyolefin separators for lithium ion batteries (including primary batteries and secondary batteries)
  • battery separators particularly polyolefin separators for lithium ion batteries (including primary batteries and secondary batteries)
  • defects of poor thermal stability in order to modify them to improve thermal stability.
  • sexuality often requires improvements based on existing membranes.
  • coating an inorganic material such as alumina on the surface of an existing (battery) membrane is a simple and efficient means of improving the thermal stability of the separator.
  • a material capable of improving the thermal stability of the separator is used in the form of a nanowire, and is loaded on the original separator. material.
  • a nanowire is used as a coating (as achieved by coating). The size and density of the one-dimensional nanowires are much smaller than those of the inorganic materials, and the thickness can be controlled to be smaller.
  • one-dimensional nanowires have the potential to create new properties or improve existing properties due to their unique structural and interfacial effects.
  • the battery separator is a multilayer composite bond.
  • the battery separator has a composite structure composed of the first member 100 and the second member 200. Further, the above battery separator structure may be modified as needed.
  • the battery separator has a composite structure composed of the first element 100 and the second element 200, and at the same time, the first element also has a plurality of holes.
  • the porous structure 300 is shown in Figure 1, this embodiment provides that the battery separator is a multilayer composite bond.
  • the battery separator has a composite structure composed of the first member 100 and the second member 200. Further, the above battery separator structure may be modified as needed. For example, in FIG. 2, the battery separator has a composite structure composed of the first element 100 and the second element 200, and at the same time, the first element also has a plurality of holes.
  • the porous structure 300 is a multilayer composite bond.
  • FIGS. 1 and 2 merely show the structure of the battery separator in a schematic manner, but the absolute thickness of the first member, the absolute thickness of the second member, and the relative thickness between the two.
  • the size ratio relationship is not based on the size and scale in the figure.
  • the thickness of the first element in the battery separator is significantly less than the thickness of the second element.
  • the thickness of the first element is on the order of submicron or micron, and the thickness of the second element can be on the order of millimeters or centimeters.
  • the thickness of the first component may be 0.01 to 1 micrometer ( ⁇ m), or the thickness of the first component is 0.03 ⁇ m, 0.05 ⁇ m, 0.08 ⁇ m, 0.1 ⁇ m, 0.4 ⁇ m, 0.6 ⁇ m. Any one of a range value determined between 0.8 ⁇ m and 1 ⁇ m or any range of values between any two point values.
  • the thickness of the first component may be specified and verified according to specific product parameter requirements and test effects, and is not specifically limited in the embodiment of the present disclosure.
  • the first element is composed of nanowires, and therefore, based on the difference in performance of the first element and the nanowire, and the difficulty of the preparation method thereof, combined with the performance consideration of the battery separator, the nanowire
  • the specifications may have the following alternative definitions, for example, the nanowires have an aspect ratio greater than 50, such as an aspect ratio of 146, 138, 127, and the like. Further, the adjustment of the aspect ratio thereof is achieved by controlling the proper length and diameter of the nanowires, for example, the nanowires have a diameter of 1 to 100 nm and a length of 0.1 to 100 ⁇ m. In some specific alternative examples, the nanowires have a diameter of 100 nm and a length of 5 [mu]m.
  • the material selection of the battery separator can be various, and it can be selected according to the actual situation.
  • the first element is made of a modified material provided to improve the thermal stability of the separator, and the first element is a stack of nanowires distributed in layers.
  • the first element is in the form of a film (film layer) having a thickness of the submicron or micron order as described above.
  • the aforementioned first element is a stack of nanowires, and the stack of nanowires may exist in various ways.
  • the first element is a single layer stack structure having a nanowire diameter, wherein the nanowires are arranged in an array. In the longitudinal direction, the nanowires in the same column are arranged end to end; in the lateral direction, the columns are arranged side by side. Or, in some examples, the nanowires are stacked in a crisscross pattern. Or, in other examples, the nanowires are staggered and staggered.
  • the manner of stacking the nanowires may be defined by the manner in which the battery separator is prepared, and is not specifically limited in the embodiment of the present disclosure. Further, the deposit composed of the nanowires may also be two layers, three layers, or even more layers, and each layer may be made of the same or different stacked forms.
  • the first element produced by the deposit formed by the nanowire in an appropriate manner has the characteristics of high porosity, uniform pore size, light weight, and high strength. Therefore, under the premise of solving the thermal stability of the polyolefin separator, the nanowire coating has the characteristics of thin thickness and light weight, and is in line with the development direction of light weight and high energy of the battery.
  • the aforementioned first element having a hole may be formed by stacking nanowires on the second element.
  • the holes can be made by a non-human active layer in the process of fabricating the battery separator, and the holes can also be considered to be purposefully controlled (distribution density, distribution mode, pore size) and formed.
  • the effect of the movement of the ions is determined by the manner in which the holes are formed, such as the aperture, the void ratio, etc., in order to adjust the application of the battery separator having the first element and the second element to the battery.
  • modifying materials such as one of carbon nanotubes, nano silver wires, boron carbide nanowires, nanocellulose, copper hydroxide nanowires, silicon oxide nanowires, and hydroxyapatite nanowires. kind or more.
  • the second element is fabricated from a base material that is provided as a body of the diaphragm, and the first element is loaded on the second element and supported by the second element.
  • the aforementioned body as a diaphragm may be the diaphragm itself in the prior art battery separator technology.
  • a separator that separates electrons and allows ions to pass therethrough it is provided and used as a body, and exerts its corresponding action on electrons and ions.
  • the modifying material for the first component has a plurality of options, and accordingly, the substrate material for the second component can be selected in a variety of ways, and can be appropriately selected depending on the specific properties and process requirements.
  • the second member is selected to be a polyolefin such as polyethylene, polypropylene or the like.
  • a battery is also provided in the embodiment of the present disclosure, which may be a primary battery or a secondary battery, such as a rechargeable lithium ion battery.
  • the battery has a casing in which the battery separator is disposed, and a positive electrode and a negative electrode separated by a battery separator. A positive electrode region is formed between the positive electrode and the battery separator, and a negative electrode region is formed between the negative electrode and the battery separator. The same electrolyte is injected into the positive electrode region and the negative electrode region.
  • a method of fabricating the battery separator is also provided accordingly.
  • Preparation methods include:
  • Step S101 providing a dispersion in which nanowires are dispersed in a dispersant.
  • the nanowires are preferably sufficiently dispersed in the dispersant, and in order to maintain the structure of the nanowires, the dispersant is generally a poor solvent for the nanowires, ie, the dispersant does not significantly dissolve the nanowires, thereby destroying the nanostructures.
  • the nanowires are also preferably uniformly dispersed in the dispersant rather than being sequestered in the dispersant.
  • the dispersion may optionally be present in the form of a suspension, suspension, emulsion, and used.
  • the dispersant is selected to be water and the nanowires are selected as carbon nanotubes. It can be uniformly dispersed in water by a vibration method such as ultrasonic treatment or high-speed stirring. Generally, the dispersion is easily prepared on site and used in the field to avoid the problem of uneven distribution of the nanowires in the dispersant. However, in some cases where the requirements are relatively not too high or dispersions which are well dispersed and stable, the dispersion may be pre-formulated or purchased. Further, the concentration of the nanowires in the dispersion may be from 0.01 to 50% by weight, for example, from 0.1 to 43% by weight, from 3 to 36% by weight, from 14 to 29% by weight, and the like.
  • the material selection of the nanowire can be referred to the foregoing, and will not be described herein.
  • the dispersing agent may be selected from one or more of water, ethanol, acetone, and N-methylpyrrolidone.
  • the adhesive may be selected from polyvinyl alcohol, polyacrylonitrile, polyacrylic acid, One or more of styrene-butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride, polyvinylpyrrolidone, and polyimide.
  • the mass concentration of the adhesive may be 0.01 to 49%, 5 to 37%, 11 to 27%, 16 to 20%, or the like.
  • an auxiliary agent may be added to the dispersant as a wetting action, including glycerin, sodium butylbenzenesulfonate, propylene glycol, and polyoxyethylene sulfide.
  • Step S102 transferring the dispersion to the surface of the second element, removing the dispersing agent in the dispersion liquid on the surface of the second element to load the nanowires in a layered manner on the surface of the second element.
  • the method of transferring the dispersion may be coating, such as spin coating or knife coating or dip coating. Removal of the dispersant in the dispersion can be achieved by evaporation, for example, heating a second component loaded with a dispersion to evaporate a dispersant such as water. The heating can be by irradiation heating.
  • the evaporation speed of the dispersion should be appropriately controlled to avoid the degree of bonding of the formed first member to the second member due to the unreasonable evaporation mode.
  • the dispersion is transferred to the surface of the second member by dip coating.
  • dip coating methods include:
  • the second member is immersed in the dispersion at a first given speed and detached from the dispersion at a second given speed under tension by stretching.
  • the second element passes through the dispersion, and the nanowires or optionally added adhesive in the dispersion are combined in the second element by chemical action and adsorption, capillary action, and the like.
  • the dispersant in the dispersion is then removed from the surface of the second component in a suitable manner while leaving the nanowires on the surface of the second component.
  • the dispersion is transferred to the second member through a film forming device.
  • the general structure of the film forming apparatus can be referred to as follows, see Fig. 3.
  • the film forming apparatus has a liquid storage tank 401 which is used to store the dispersion.
  • the film forming apparatus also has a tensioning system 402.
  • the tensioning system includes a plurality of rollers.
  • the tensioning system comprises three rollers, one of which is distributed between the other two rollers, and the center point of the projection of the three rollers on the plane can form a triangle.
  • the second element in the battery diaphragm is tensioned by a tensioning system having at least one dip coating roller 403 for immersing the second member 200 in the dispersion (i.e., the roller located in the middle portion), dip coating Part or all of the shaft is immersed in the dispersion (in one example, the immersion depth is 1/4 of its radius to full immersion).
  • the immersion depth of the dip-coated roller can be achieved by a moving mechanism (not shown) which enables the immersion roller to be moved in a suitable manner, such as vertically, relative to the dispersion.
  • the tensioning system can properly release the second member to adjust the immersion depth of the dip coating roller without moving the two rollers outside the dip roller.
  • the three rollers that make up the tensioning system are movable, making it easier to control the immersion depth adjustment of the dip coating roller.
  • the dip coating roller 403 has a hollow cavity 4031, and the dip coating roller has a vent channel 4032 that communicates with the hollow cavity and extends to the surface.
  • the second component is in contact with the surface of the dip coating roller in a face-to-face manner, and has a given degree of vacuum in the hollow cavity, for example, a degree of vacuum of 0.01 to 0.1 MPa.
  • a vacuum generator diagram for causing the dip coating roller to produce a desired degree of vacuum is not shown, and a commercially available vacuum pump or the like can be used.
  • the dispersion is more easily adsorbed and bonded to the surface of the second member under the action of the negative pressure.
  • the pore passage of the dip coating roller it is also possible to modulate the porosity, pore size, and pore distribution pattern of the first member to achieve the desired effect.
  • the adjustment of the thickness of the first member can be achieved by adjusting the concentration of the nanowires in the dispersion, the depth of the dip coating roller immersed in the dispersion, and the degree of vacuum of the dip coating roller.
  • concentration of the nanowires in the dispersion the concentration of the nanowires in the dispersion
  • depth of the dip coating roller immersed in the dispersion the depth of the dip coating roller immersed in the dispersion
  • degree of vacuum of the dip coating roller The inventors have found that the thicker the solution, the thicker the coating; the deeper the immersion, the thicker the coating; the higher the vacuum, the thicker the coating.
  • the battery separator is a sheet structure having a multilayer film structure.
  • the second element constitutes a base film
  • the first element constitutes a surface film.
  • the surface film may be one layer or multiple layers. When the surface film has a plurality of layers, it may be respectively distributed on two sides in the thickness direction of the base film, and the number of layers of the surface film distributed on each side may be different or the same, or may be distributed only in the two sides in the thickness direction. Any one of them.
  • Table 1 lists examples of a plurality of battery separators, including the materials of manufacture, process methods, and properties.
  • the battery was fabricated using the battery separator prepared in the above Examples 1-4, and the electrical properties were examined. The test results are shown in Table 2 below.
  • Table 2 shows the battery performance of the battery separator.
  • the batteries of Examples 1-4 and Comparative Examples 1-6 have the same main structure including a positive electrode, a negative electrode, an electrolyte, and a separator.
  • the separator of the battery of Examples 1-4 was produced by the method proposed in the examples of the present disclosure and loaded with a nanowire coating; the separator of the battery of Comparative Examples 1-4 was a commercially available product. It is loaded with a millimeter-scale coating of particulate matter.
  • the separator of the battery of Comparative Example 5-6 was a commercially available product and was not loaded with a substance for forming a coating.
  • the polyethylene film or the polypropylene film can be produced, for example, by a wet non-woven process.
  • the battery separator provided by the present disclosure has a composite structure which is an innovation of the existing battery separator and improves its thermal stability by using a modified material. Further, the use of the modified material in the form of a nanowire can avoid the problem of an increase in the thickness and weight of the separator due to the introduction of the modified material, thereby achieving the effects of thermal stability, thickness and weight increase of the battery separator.

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Abstract

一种电池、电池隔膜及其制备方法,属于电池领域。电池隔膜具有第一元件和第二元件构成的复合结构。隔膜包括:第一元件由被提供来改善隔膜的热稳定性的改性材料制作而成,第一元件是以层状分布的纳米线的堆积体。第二元件由被提供来作为隔膜的本体的基底材料制作而成,第一元件负载在第二元件、并且受到第二元件的支撑。电池隔膜具有好的热稳定性。

Description

一种电池、电池隔膜及其制备方法
相关申请的交叉引用
本申请要求于2018年05月16日提交中国国家知识产权局的申请号为2018104718423、名称为“一种电池、电池隔膜及其制备方法”的中国专利申请的优先权,其全部内容通过引用结合在本申请中。
技术领域
本公开涉及电池领域,具体而言,涉及一种电池、电池隔膜及其制备方法。
背景技术
锂离子电池是一种目前使用广泛的二次电池。锂离子电池主要依靠锂离子在正极和负极之间移动来工作。在充放电过程中,Li +在两个电极之间往返嵌入和脱嵌。充电时,Li +从正极脱嵌,经过电解质嵌入负极,负极处于富锂状态,且负极嵌入的锂离子越多,充电容量越高);放电时则相反,嵌在负极碳层的锂离子脱出,又通过电解质运动回到正极,回到正极的锂离子越多,放电的容量越高。
锂离子电池具有单体电池工作电压高、比能量大、循坏寿命长、自放电小、无公害、无记忆效应等优点,因而其被广泛应用于手机、便携式设备、汽车、航空、科研、娱乐和军事等现代电子领域,并逐步取代传统电池。
锂离子电池主要由四大材料构成,包括正极材料、负极材料、隔膜、电解液。作为其重要的组成部分之一,隔膜对其性能起到相当重要的作用。电池隔膜(battery separator)是指在电池的正极和负极之间的一层隔膜材料,通常以 电池隔膜称之。电池隔膜的主要作用是:隔离正、负极并使电池内的电子不能自由穿过,同时允许电解液中的离子在正负极之间自由通过。
电池隔膜的离子传导能力直接关系到电池的整体性能。其隔离正负极的作用使电池在过度充电或者温度升高的情况下能限制电流的升高,防止电池短路引起爆炸,具有微孔自闭保护作用,对电池使用者和设备起到安全保护的作用。由于聚烯烃材料价格低廉,且有较好的机械强度和化学稳定性、综合性能良好、成本低廉等优点而被广泛地用作微孔隔膜。但是,由于其存在热稳定性方面的不足的问题,因此限制了其在电池中的进一步应用。
公开于该背景技术部分的信息仅仅旨在加深对本公开的总体背景技术的理解,而不应当被视为承认或以任何形式暗示该信息构成已为本领域技术人员所公知的现有技术。
发明内容
本公开提供了一种电池隔膜。
电池隔膜具有第一元件和第二元件构成的复合结构。
隔膜包括:
第一元件由被提供来改善电池隔膜的热稳定性的改性材料制作而成,第一元件是以层状分布的纳米线的堆积体;
第二元件由被提供来作为电池隔膜的本体的基底材料制作而成,第一元件负载在第二元件、并且受到第二元件的支撑。
在一个或多个示例中,第一元件的厚度为微米和/或亚微米级以下。
在一个或多个示例中,第一元件的厚度为0.01~1μm。
在一个或多个示例中,纳米线的长径比大于50。
在一个或多个示例中,纳米线的直径为1~100nm,长度为0.1~100μm。
在一个或多个示例中,改性材料包括碳纳米管、纳米银线、碳化硼纳米线、纳米纤维素、氢氧化铜纳米线、一氧化硅纳米线、羟基磷灰石纳米线中的一种或多种。
在一个或多个示例中,基底材料为有机高分子材料。
在一个或多个示例中,有机高分子材料包括聚烯烃。
在一个或多个示例中,聚烯烃包括聚乙烯。
在一个或多个示例中,第一元件具有多孔结构。
本公开还提供了一种制作上述电池隔膜的方法。
电池隔膜的制备方法用于制作具有如下结构的电池隔膜。
电池隔膜包括第一元件和第二元件,其中,第一元件以层状方式负载在第二元件,且第一元件由纳米线构成;
制备方法包括:
提供在分散剂中分散有纳米线的分散液;
将分散液转移至第二元件表面,去除在第二元件表面的分散液中的分散剂以使纳米线以层状的方式负载第二元件表面。
在一个或多个示例中,分散剂包括水、乙醇、丙酮、N-甲基吡咯烷酮中的一种或多种,分散液中还包含有胶粘剂。
在一个或多个示例中,胶粘剂包括聚乙烯醇、聚丙烯腈、聚丙烯酸、丁苯橡胶、羧甲基纤维素、聚偏氟乙烯、聚乙烯吡咯烷酮、聚酰亚胺中的一种或多种。
在一个或多个示例中,分散液中还包括助剂。
在一个或多个示例中,分散液中的纳米线的质量浓度为0.01~50%,胶粘 剂的质量浓度为0.01~49%。
在一个或多个示例中,分散液是通过涂覆的方式被转移至二元件表面的。
在一个或多个示例中,涂覆的方式包括旋涂或刮涂或浸涂。
在一个或多个示例中,分散液是通过浸涂的方式被转移至第二元件表面,浸涂的方法包括:
使第二元件通过拉伸而张紧的条件下,以第一给定速度浸入分散液并以第二给定速度从分散液中脱离。
在一个或多个示例中,第二元件是由多个滚轴组成的张紧系统而被张紧的,张紧系统中至少具有一个使第二元件浸入分散液的浸涂滚轴,浸涂滚轴的部分或全部浸入分散液。
在一个或多个示例中,浸涂滚轴具有中空腔,且浸涂滚轴具有与中空腔连通且延伸至表面的气孔通道,第二元件以面面贴合的方式接触于浸涂滚轴表面,中空腔内具有给定的真空度。
在一个或多个示例中,真空度为0.01~0.1MPa。
本公开还提供了一种电池,其具有如上所述的电池隔膜。
有益效果:
本公开提供的电池隔膜具有复合结构,其对现有的电池隔膜进行了革新,通过使用改性材料来改善其热稳定性。进一步地,改性材料以纳米线的方式使用,可以避免由于改性材料的引入而导致隔膜的厚度和重量增加的问题,从而达到了电池隔膜热稳定、厚度和重量增加小的作用。
附图说明
为了更清楚地说明本公开实施例的技术方案,下面将对实施例中所需要使 用的附图作简单地介绍,应当理解,以下附图仅示出了本公开的某些实施例,因此不应被看作是对范围的限定,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其他相关的附图。
图1为本公开实施例提供的第一种电池隔膜的结构示意图;
图2为本公开实施例提供的第二种电池隔膜的结构示意图;
图3为本公开实施例提供的用于制作第二种电池隔膜的成膜装置的结构示意图;
图4示出了图3的成膜装置中的浸涂滚轴的第一视角的结构示意图;
图5示出了图3的成膜装置中的浸涂滚轴的第二视角的结构示意图;
图6示出了图3的成膜装置中的浸涂滚轴的沿轴向剖开的剖面结构示意图。
图标:100-第一元件;200-第二元件;300-多孔结构;401-存储槽;402-张紧系统;403-浸涂滚轴;4031-中空腔;4032-气孔通道;200-第二元件。
具体实施方式
为使本公开实施例的目的、技术方案和优点更加清楚,下面将结合本公开实施例中的附图,对本公开实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例是本公开一部分实施例,而不是全部的实施例。通常在此处附图中描述和示出的本公开实施例的组件可以以各种不同的配置来布置和设计。因此,以下对在附图中提供的本公开的实施例的详细描述并非旨在限制要求保护的本公开的范围,而是仅仅表示本公开的选定实施例。基于本公开中的实施例,本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例,都属于本公开保护的范围。
应注意到:相似的标号和字母在下面的附图中表示类似项,因此,一旦某一项在一个附图中被定义,则在随后的附图中不需要对其进行进一步定义和解释。
在本公开的描述中,需要说明的是,术语“中心”、“上”、“下”、“左”、“右”、“竖直”、“水平”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系,或者是该公开产品使用时惯常摆放的方位或位置关系,仅是为了便于描述本公开和简化描述,而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作,因此不能理解为对本公开的限制。此外,术语“第一”、“第二”、“第三”等仅用于区分描述,而不能理解为指示或暗示相对重要性。
在本公开的描述中,还需要说明的是,除非另有明确的规定和限定,术语“设置”、“安装”、“相连”、“连接”应做广义理解,例如,可以是固定连接,也可以是可拆卸连接,或一体地连接;可以是机械连接,也可以是电连接;可以是直接相连,也可以通过中间媒介间接相连,可以是两个元件内部的连通。对于本领域的普通技术人员而言,可以具体情况理解上述术语在本公开中的具体含义。
在本公开中,除非另有明确的规定和限定,第一特征在第二特征之“上”或之“下”可以包括第一和第二特征直接接触,也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且,第一特征在第二特征“之上”、“上方”和“上面”包括第一特征在第二特征正上方和斜上方,或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”包括第一特征在第二特征正下方和斜下方,或仅仅表示第一特征水平高度小于第二特征。
在本公开中,在不矛盾或冲突的情况下,本公开的所有实施例、实施方式以及特征可以相互组合。在本公开中,常规的设备、装置、部件等,既可以商购,也可以根据本公开公开的内容自制。在本公开中,为了突出本公开的重点,对一些常规的操作和设备、装置、部件进行的省略,或仅作简单描述。
由于在现有技术中,电池隔膜,特别是用于锂离子电池(包括一次电池和二次电池)的聚烯烃隔膜往往存在热稳定性不佳的缺陷,为了对其进行改性以提高热稳定性,常常需要在现有的隔膜基础上进行改进。在实践中,发明人发现,在现有的(电池)隔膜表面涂覆氧化铝等无机材料是一种能够改善隔膜热稳定性的简单、高效的手段。
然而,发明人同时也发现,现有涂覆方式将导致被调整的隔膜的一些特性被不利地影响,例如厚度和重量显著地增加,进而导致隔膜的使用性能下降。
在本实施例中,为了兼顾隔膜的热稳定性,以及厚度和重量方面不发生明显的增加,通过将能够使隔膜的热稳定性提高的材料以纳米线的方式使用,并且使其负载在原隔膜材料。在本实施例中采用维纳米线作为覆层(如通过涂覆实现)材料,一维纳米线尺寸和密度远小于无机材料,其厚度可以被控制到更小。
另外,一维纳米线因其独特的结构特征和界面效应而具有使隔膜产生新的特性或对现有特性的改善的潜力。
参阅图1至图6。
如图1所示,本实施例提供了电池隔膜是一种多层的复合结合。电池隔膜具有第一元件100和第二元件200构成的复合结构。进一步地,根据需要还可以对以上的电池隔膜结构进行改性,例如在图2中,电池隔膜具有第一元件100和第二元件200构成的复合结构,并同时第一元件还具有多个孔洞的多孔 结构300。
另外,应该认识到,图1和图2仅仅是以示意的方式示出了电池隔膜的结构,但是其中的第一元件的绝对厚度、第二元件的绝对厚度,以及两者厚度之间的相对大小比例关系,并不能根据图中的尺寸和比例而定。但是,电池隔膜中的第一元件的厚度是显著小于第二元件的厚度的。
例如,在一些示例中,第一元件的厚度为亚微米级或者微米级,第二元件的厚度为可以为毫米或厘米级。在一些更具体的可选示例中,第一元件的厚度可以是0.01~1微米(μm),或者,第一元件的厚度是0.03μm、0.05μm、0.08μm、0.1μm、0.4μm、0.6μm、0.8μm、1μm中的任意点值或任意两个点值之间确定的范围值中任意一个数值。此外,第一元件的厚度可以根据具体是产品参数要求和试验效果进行规范和验证,在本公开实施例中不对其做具体限定。
进一步地,在本实施例中,第一元件是由纳米线构成,因此,基于第一元件以及纳米线的性能的差异,及其制备方法的难以程度,再结合电池隔膜的性能考量,纳米线的规格可以具有以下可替代的限定,例如,纳米线的长径比大于50,例如长径比为146、138、127等等。更进一步,通过控制纳米线的恰当长度和直径来实现对其长径比的调节,例如,纳米线的直径为1~100nm,长度为0.1~100μm。在一些具体的可选示例中,纳米线的直径为100nm、长度为5μm。
电池隔膜的材料选择可以有多种,根据具体实际情况选择。
其中,第一元件由被提供来改善隔膜的热稳定性的改性材料制作而成,且第一元件是以层状分布的纳米线的堆积体。通常地,在宏观形貌上,第一元件是以薄膜(膜层)的形式存在,其厚度如前述为亚微米级或者微米级。
另外,前述的第一元件是纳米线的堆积体,而纳米线的堆积体可以存在多 种方式。例如,第一元件是具有纳米线直径的单层的堆积体结构,其中,纳米线呈阵列排布。在纵向上,同一列中的纳米线首尾依序排列;在横向上,多列并排布置。或者,在一些示例中,纳米线是纵横交错地堆积的。或者,在另一些示例中,纳米线是杂乱地交错堆积的。纳米线的堆积方式可由电池隔膜的制备方式来限定,在本公开实施例中并不作具体限定。进一步地,纳米线构成的堆积体还可以是两层、三层以至于更多层,每一层的制作方法和堆积形式都可以是相同或不同。
由纳米线以适当方式形成的堆积体所产生的第一元件具有孔隙率高、孔径均匀、质量轻、强度高的特点。因此纳米线涂层将在解决聚烯烃隔膜热稳定性的前提下,具有厚度薄,重量轻的特点,符合电池轻量化,高能量的发展方向。
另外,前述的具有孔洞的第一元件可以是通过纳米线在第二元件上的堆积方式来形成。换言之,孔洞既可以是在制作电池隔膜的工艺中非人为主动制作而成层,同时孔洞也可以是认为有目的地控制(分布密度、分布方式、孔径大小)和形成的。通过对孔洞的构成方式—如孔径、空隙率等—以便调节将具有第一元件和第二元件的电池隔膜应用在电池中时,其对离子的运动影响。
承上述,改性材料有多种选择,例如碳纳米管、纳米银线、碳化硼纳米线、纳米纤维素、氢氧化铜纳米线、一氧化硅纳米线、羟基磷灰石纳米线中的一种或多种。
第二元件由被提供来作为隔膜的本体的基底材料制作而成,且第一元件负载在第二元件、并且受到第二元件的支撑。应当指出的是,前述的作为隔膜的本体可以是现有电池隔膜技术中的隔膜自身。在本实施例中,作为隔离电子,且允许离子通过的隔膜是作为本体被提供和使用,并且发挥其对电子和离子的相应作用。
正如前述,制作第一元件的改性材料具有多种选择,相应地,制作第二元件的基底材料也可以存在多种选择,并且可根据具体的性能和工艺要求进行适当的选择。
在本实施例中,可选地,第二元件被选择采用为聚烯烃,如聚乙烯、聚丙烯等等。
基于以上电池隔膜,本公开实施例中还提供有一种电池,其可以是一次电池或二次电池,例如可以是可充电的锂离子电池。电池具有壳体,壳体内设置有上述电池隔膜,以及由电池隔膜分隔开的正极、负极。正极和电池隔膜之间形成正极区,负极和电池隔膜之间形成负极区。正极区和负极区内注入有相同的电解液。
对应于以上的电池隔膜,在本公开实施例中,还相应提供了电池隔膜的制作方法。
制备方法包括:
步骤S101、提供在分散剂中分散有纳米线的分散液。
其中纳米线优选充分地分散在分散剂中,并且为了保持其纳米线的结构,通常分散剂是纳米线的不良溶剂,即分散剂不会显著地溶解纳米线,进而破坏其纳米结构。
另外,纳米线也优选均匀地分散在分散剂中,而不是聚沉于分散剂中。在一些示例中,分散液可以选择以悬浮液、悬浊液、乳浊液的方式存在并被使用。
在本公开的一些实施例中,作为示例,分散剂选择用为水,纳米线选择为碳纳米管。其可通过超声波处理、高速搅拌等振动方式而均匀地分散在水中。通常地,分散液易采用现场配制、现场使用,避免纳米线在分散剂中分布不均的问题。但是,在一些要求相对不是太高的场合或分散均匀性较好且稳定的分 散液而言,分散液可以预先配制或外购使用。另外,纳米线在分散液中的浓度可以为0.01~50wt%,例如,0.1~43wt%、3~36wt%、14~29wt%等等。
纳米线的材质选择可参见前述,在此不再赘述。
在一些改进的方案中,为了改善第一元件与第二元件之间的结合牢固性,通常还可以分散剂中还可以添加胶粘剂,并且胶粘剂通常是能够与分散剂相容的,即不会出现显著的分层等影响纳米线的分布均匀性的现象。
例如,在本实施例中,分散剂可选择为水、乙醇、丙酮、N-甲基吡咯烷酮中的一种或多种,相应地,胶粘剂可以选择为聚乙烯醇、聚丙烯腈、聚丙烯酸、丁苯橡胶、羧甲基纤维素、聚偏氟乙烯、聚乙烯吡咯烷酮、聚酰亚胺中的一种或多种。胶粘剂的质量浓度可以是0.01~49%、5~37%、11~27%、16~20%等等。
进一步地,分散剂中还可以添加助剂,作为润湿作用,包括甘油,丁基苯磺酸钠,丙二醇,聚氧乙烯基硫醚。
步骤S102、将分散液转移至第二元件表面,去除在第二元件表面的分散液中的分散剂以使纳米线以层状的方式负载第二元件表面。
其中,转移分散液的方式可以是涂覆,例如旋涂或刮涂或浸涂。去除分散液中分散剂可以通过蒸发的方式来实现,例如,将负载有分散液的第二元件进行加热使分散剂(如水)蒸发。加热的方式可以是辐照加热。另外,应当适当地控制分散液的蒸发速度,避免由于蒸发方式的不合理而影响到形成的第一元件在第二元件上的结合牢固程度。
在本公开的较佳的改进示例中,分散液是通过浸涂的方式被转移至第二元件表面。
例如,浸涂的方法包括:
使第二元件通过拉伸而张紧的条件下,以第一给定速度浸入分散液并以第 二给定速度从分散液中脱离。第二元件在分散液中穿过,分散液中的纳米线或可选加入的胶粘剂通过化学作用和吸附作用、毛细管现象等作用结合在第二元件。然后,使分散液中分散剂以适当的方式被从第二元件表面去除,同时保留纳米线在第二元件表面。
特别地,在本实施例中,分散液通过一个成膜装置来转移到第二元件。成膜装置的大致结构可参加如下,参阅图3。
成膜装置具有液体存储槽401,其被用以存储分散液。
成膜装置还具有张紧系统402。张紧系统包括多个滚轴。在图3中,张紧系统包括三个滚轴,其中,有一个滚轴分布在另两个滚轴之间,三个滚轴在平面上的投影的中心点可构成一个三角型。电池隔膜中的第二元件是由张紧系统张紧,张紧系统中至少具有一个使第二元件200浸入分散液的浸涂滚轴403(即上述位于中间部分的滚轴),浸涂滚轴的部分或全部浸入分散液(一种示例中,浸入深度为其半径的1/4至完全浸入)。
浸涂滚轴的浸没深度可以通过移动机构(图中未示出)来实现,其可以实现使浸没滚轴相对于分散液以适当的方式如垂直地运动。同时张紧系统可以适当地释放第二元件,以便在浸涂滚轴之外的两个滚轴不移动位置的情况下,调节浸涂滚轴的浸没深度。或者,在一些示例中,构成张紧系统的三个滚轴均能够运动,从而更易于控制浸涂滚轴的浸没深度调节。
更优选地,浸涂滚轴403具有中空腔4031,且浸涂滚轴具有与中空腔连通且延伸至表面的气孔通道4032。第二元件以面面贴合的方式接触于浸涂滚轴表面,中空腔内具有给定的真空度,例如真空度为0.01~0.1MPa。用于使浸涂滚轴产生期望真空度的真空发生器图未示出,其可采用市售真空泵等设备。
通过这样处理方式,第二元件在经过分散液时,分散液更易在负压作用下 吸附、结合在第二元件表面。另一方面,通过控制浸涂滚轴的气孔通道还能够对第一元件的孔隙率,孔径、孔分布方式进行调制,以达到期望的效果。
另外,根据分散液中的纳米线的浓度、浸涂滚轴浸没在分散液中的深度、浸涂滚轴的真空度的调节可以实现对第一元件厚度的调节。发明人发现,溶液浓度越大,涂层越厚;浸入深度越深,涂层越厚;真空度越高,涂层越厚。
另外,应当指出的是,在本公开实施例中,电池隔膜是一种片式结构,具有多层膜结构。其中,第二元件构成基底膜,第一元件构成表面膜。表面膜可以是一层也可以是多层。当表面膜存在多层时,其可以分别分布在基底膜的厚度方向的两个侧面,每个侧面分布的表面膜的层数可以不同也可以相同,或者仅仅分布在厚度方向的两个侧面中的任意一个。
以下表1列举了多个电池隔膜的实施例,包括其制作原料、工艺方法以及性能。
表1电池隔膜的制作及性能
Figure PCTCN2019085704-appb-000001
采用上述实施例1-4中所制备的电池隔膜制作电池,并对其电学性能进行检测,检测结果如下表2。
表2应用电池隔膜的电池性能。
Figure PCTCN2019085704-appb-000002
Figure PCTCN2019085704-appb-000003
表2中,实施例1-4、对比例1-6中的电池具有相同的主体结构,包括正极、负极、电解液以及隔膜。
各个主要区别在于,实施例1-4中的电池的隔膜是采用本公开实施例中提出的方法制作的且负载有纳米线涂层;对比例1-4中的电池的隔膜是采用市售产品且负载有毫米级别的颗粒状物质涂层。对比例5-6的电池的隔膜是采用市售产品,且未负载用于形成涂层的物质。各个实施例和对比例中的电池隔膜的基体如聚乙烯膜、聚丙烯膜均是市售产品。聚乙烯膜、聚丙烯膜例如可通过湿法非织造工艺制作而成。
由以上表1和表2可知,采用本公开实施例提供的电池隔膜,电池隔膜的 热稳定性被的显著地改善,并且同时在一定程度上改善了电池的电池容量的保持率。以上表1和表2,TD表示隔膜在横向的热稳定性(热水收率)、MD表示在纵向的热稳定性(热收缩率)。
以上所述仅为本公开的优选实施例而已,并不用于限制本公开,对于本领域的技术人员来说,本公开可以有各种更改和变化。凡在本公开的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本公开的保护范围之内。
工业实用性
本公开提供的电池隔膜具有复合结构,其对现有的电池隔膜进行了革新,通过使用改性材料来改善其热稳定性。进一步地,改性材料以纳米线的方式使用,可以避免由于改性材料的引入而导致隔膜的厚度和重量增加的问题,从而达到了电池隔膜热稳定、厚度和重量增加小的作用。

Claims (19)

  1. 一种电池隔膜,其特征在于,所述电池隔膜具有第一元件和第二元件构成的复合结构,所述电池隔膜包括:
    所述第一元件由被提供来改善所述电池隔膜的热稳定性的改性材料制作而成,所述第一元件是以层状分布的纳米线的堆积体;
    所述第二元件由被提供来作为所述电池隔膜的本体的基底材料制作而成,所述第一元件负载在所述第二元件、并且受到所述第二元件的支撑。
  2. 根据权利要求1所述的电池隔膜,其特征在于,所述第一元件的厚度为微米和/或亚微米级以下。
  3. 根据权利要求1所述的电池隔膜,其特征在于,所述第一元件的厚度为0.01~1μm。
  4. 根据权利要求1所述的电池隔膜,其特征在于,所述纳米线的长径比大于50。
  5. 根据权利要求4所述的电池隔膜,其特征在于,所述纳米线的直径为1~100nm,长度为0.1~100μm。
  6. 根据权利要求1所述的电池隔膜,其特征在于,所述改性材料包括碳纳米管、纳米银线、碳化硼纳米线、纳米纤维素、氢氧化铜纳米线、一氧化硅纳米线、羟基磷灰石纳米线中的一种或多种。
  7. 根据权利要求1所述的电池隔膜,其特征在于,所述基底材料为有机高分子材料,优选地,所述有机高分子材料包括聚烯烃,更优选地,所述聚烯烃包括聚乙烯。
  8. 根据权利要求1所述的电池隔膜,其特征在于,第一元件具有多孔结构。
  9. 一种电池隔膜的制备方法,其特征在于,所述电池隔膜包括第一元件和第二元件,其中,所述第一元件以层状方式负载在所述第二元件,且 所述第一元件由纳米线构成;
    所述制备方法包括:
    提供在分散剂中分散有所述纳米线的分散液;
    将所述分散液转移至所述第二元件表面,去除在所述第二元件表面的所述分散液中的所述分散剂以使所述纳米线以层状的方式负载在所述第二元件表面。
  10. 根据权利要求9所述的电池隔膜的制备方法,其特征在于,所述分散剂包括水、乙醇、丙酮、N-甲基吡咯烷酮中的一种或多种。
  11. 根据权利要求10所述的电池隔膜的制备方法,其特征在于,所述分散液中还包含有胶粘剂,优选地,所述胶粘剂包括聚乙烯醇、聚丙烯腈、聚丙烯酸、丁苯橡胶、羧甲基纤维素、聚偏氟乙烯、聚乙烯吡咯烷酮、聚酰亚胺中的一种或多种,更优选地,所述分散液中还包括助剂。
  12. 根据权利要求10所述的电池隔膜的制备方法,其特征在于,分散液中的纳米线的质量浓度为0.01~50%,所述胶粘剂的质量浓度为0.01~49%。
  13. 根据权利要求9所述的电池隔膜的制备方法,其特征在于,所分散液是通过涂覆的方式被转移至所述二元件表面的,优选地,所述涂覆的方式包括旋涂或刮涂或浸涂。
  14. 根据权利要求9所述的电池隔膜的制备方法,其特征在于,所分散液是通过浸涂的方式被转移至所述第二元件表面,所述浸涂的方法包括:
    使所述第二元件通过拉伸而张紧的条件下,以第一给定速度浸入所述分散液并以第二给定速度从所述分散液中脱离;
    优选地,所述第二元件是由多个滚轴组成的张紧系统而被张紧的,所述张紧系统中至少具有一个使所述第二元件浸入所述分散液的浸涂滚轴,所述浸涂滚轴的部分或全部浸入所述分散液;
    更优选地,所述浸涂滚轴具有中空腔,且所述浸涂滚轴具有与所述中 空腔连通且延伸至表面的气孔通道,所述第二元件以面面贴合的方式接触于所述浸涂滚轴表面,所述中空腔内具有给定的真空度,进一步优选地,所述真空度为0.01~0.1MPa。
  15. 一种电池,其特征在于,所述电池具有如权利要求1至8中任意一项所述的电池隔膜。
  16. 根据权利要求15所述的电池,其特征在于,所述电池是锂离子电池。
  17. 根据权利要求16所述的电池,其特征在于,所述锂离子电池是可充电的锂离子电池。
  18. 根据权利要求15所述的电池,其特征在于,所述电池包括壳体,所述壳体内设置有所述电池隔膜,以及由所述电池隔膜分隔开的正极和负极;所述正极和所述电池隔膜之间形成正极区,所述负极和所述电池隔膜之间形成负极区。
  19. 根据权利要求18所述的电池,其特征在于,所述正极区和所述负极区内注入有相同的电解液。
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