CN116376280A - Poly (p-phenylene benzobisoxazole) porous membrane, preparation method and application thereof, composite membrane and battery - Google Patents

Poly (p-phenylene benzobisoxazole) porous membrane, preparation method and application thereof, composite membrane and battery Download PDF

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CN116376280A
CN116376280A CN202310264509.6A CN202310264509A CN116376280A CN 116376280 A CN116376280 A CN 116376280A CN 202310264509 A CN202310264509 A CN 202310264509A CN 116376280 A CN116376280 A CN 116376280A
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porous membrane
battery
composite
poly
coating
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杨春鹏
鲁浩天
杨全红
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Tianjin University
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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
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C08J9/365—Coating
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
    • C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C09D127/16—Homopolymers or copolymers of vinylidene fluoride
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/18—Fireproof paints including high temperature resistant paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • 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
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2427/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08J2427/16—Homopolymers or copolymers of vinylidene fluoride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/38—Boron-containing compounds
    • C08K2003/382—Boron-containing compounds and nitrogen
    • C08K2003/385—Binary compounds of nitrogen with boron
    • C—CHEMISTRY; METALLURGY
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    • C08K2201/00—Specific properties of additives
    • C08K2201/011—Nanostructured additives
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    • 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

Abstract

The invention discloses a poly-p-phenylene benzobisoxazole porous membrane, a preparation method and application thereof, a composite diaphragm and a battery, wherein poly-p-phenylene benzobisoxazole fibers are subjected to acid dissolution and uniformly stirred to obtain fiber slurry; pouring into a mould, spreading and soaking in an exchange solvent, and deacidifying to obtain a colloidal block; and (3) rapidly desolventizing and drying the colloidal block to finally obtain the poly-p-phenylene benzobisoxazole porous membrane which has the characteristics of high mechanical property, no heat-shrinking and tiredness, incombustibility and high thermal decomposition temperature. The composite diaphragm is prepared by simple casting film forming, coating and drying, and the preparation process is simple and is suitable for large-scale production. The composite diaphragm has the advantages of excellent electrochemical stability, dendrite resistance effect, high mechanical property, good ion transmission performance, fast heat conduction, high temperature resistance, closed pore at high temperature and the like, and can prolong the cycle life and improve the safety performance of a battery.

Description

Poly (p-phenylene benzobisoxazole) porous membrane, preparation method and application thereof, composite membrane and battery
Technical Field
The invention relates to the technical field of electrochemical power sources, in particular to a micro-short circuit prevention heat-resistant diaphragm, a preparation method and application thereof and a high-safety battery.
Background
With the establishment of social informatization, equipment intellectualization, traffic electrification and energy Internet of things, energy storage modes and energy storage devices are continuously innovatively developed. The battery is used as an electrochemical energy storage device and has wide application in the fields of 3C electronic products, power automobiles, new energy sources and the like. In order to meet the mileage and market demand of electric automobiles, research and industry are advancing the development and application of high energy density batteries, such as lithium metal negative electrode, silicon negative electrode, high nickel ternary positive electrode, air positive electrode. However, as the energy density of the battery increases, the stability of the battery also deteriorates, such as dendrite growth of the lithium metal anode, high volume expansion during charging of the silicon anode, poor thermal stability of the high nickel anode, and the like. These instability factors tend to cause short circuits and thermal runaway of the battery, which presents a significant challenge for the safety of the battery.
The diaphragm is used as an important component of the liquid battery, can effectively separate the anode from the cathode to prevent short circuit, but can permit ion transmission to prevent electrons from passing, and is an important guarantee component for the safety of the battery. Conventional separators mainly employ polyolefin porous films such as polyethylene films and polypropylene films. However, the polyolefin separator has a low melting point and thermal decomposition temperature, poor thermal conductivity, and when heat aggregation occurs inside the battery, the polyolefin separator is liable to thermally shrink, and causes a short circuit of the battery. In addition, the mechanical properties of the polyolefin separator are not high, and when dendrites or large volume changes occur in the electrode, the polyolefin separator is easily pierced and broken, and short circuit of the battery is also caused. The internal short circuit of the battery can aggravate the thermal runaway behavior of the battery and even cause potential safety hazards such as liquid leakage, explosion or fire disaster. In order to ensure the safety of the high energy density battery, the separator responsible for safety assurance should have the characteristics of high rupture temperature, low thermal shrinkage, fast heat conduction, high tensile strength, proper closed cell temperature, and the like.
The thermal decomposition temperature of the poly-p-phenylene benzobisoxazole fiber is higher than 650 ℃, the poly-p-phenylene benzobisoxazole fiber has no melting point, is nonflammable and does not support combustion, has 12-14 times of mechanical strength as steel, is light and soft, and is called 21 st century super fiber. As a high-strength heat-resistant nonflammable organic fiber, the fiber is an ideal raw material for the diaphragm. However, the molecular chain of poly-p-phenylene benzobisoxazole contains benzene rings and benzobisoxazole rings, and the molecular chains are tightly gathered together under the action of large pi bonds between ring planes, so that the poly-p-phenylene benzobisoxazole is difficult to disperse and dissolve in a conventional solvent. Although the porous membrane can be dissolved in strong acid, after protons in the acidic slurry are washed out, molecular chains are tightly agglomerated together under the action of large pi bond conjugation, and a flat and porous poly (p-phenylene benzobisoxazole) porous membrane is difficult to form. Although there are few reports on the method for preparing the poly-p-phenylene benzobisoxazole porous membrane, the prepared porous membrane has smaller size and limited pore number (such as patent CN103746086B and Nano letters 16 (2016) 2981-2987.), is unfavorable for ion transmission, can not be used under high current, and is not suitable for being used as a diaphragm of a power battery. Meanwhile, these porous films do not have high Wen Bikong characteristics, which is disadvantageous in blocking the occurrence of thermal runaway. In addition, for example, some common methods of composite copolymerization (CN 103788395A, CN113174196 a) are complex in steps, harsh in conditions, high in energy consumption, and not smooth enough in the obtained porous membrane, which is unfavorable for low-cost large-scale preparation. Meanwhile, the poly-p-phenylene benzobisoxazole contains an oxazole group, has chemical instability when being in direct contact with a plurality of active metal cathodes, and is not suitable to be directly used as a diaphragm material of a high-energy-density metal battery.
In view of the above, the poly-p-phenylene benzobisoxazole porous membrane is prepared and modified, so that a composite separator which is heat-resistant, free of thermal shrinkage, high in strength, fast in heat conduction, stable in chemistry and electrochemistry, and high in Wen Bikong characteristics is obtained, and is successfully applied to a battery, and is particularly important for improving the safety of the battery, especially the thermal safety.
Disclosure of Invention
The invention aims at overcoming the technical defects in the prior art and provides a polyparaphenylene benzobisoxazole porous membrane.
Another object of the present invention is to provide a micro-short circuit-proof and heat-resistant composite separator based on the polyparaphenylene benzobisoxazole porous membrane.
The invention further aims at providing a preparation method of the micro-short circuit-proof heat-resistant composite membrane.
It is another object of the present invention to provide the use of the micro-short circuit resistant and heat resistant composite separator in a battery.
It is another object of the present invention to provide a high safety battery based on the micro-short circuit-proof and heat-resistant composite separator.
The technical scheme adopted for realizing the purpose of the invention is as follows:
a polyparaphenylene benzobisoxazole porous membrane prepared by the steps of: carrying out acid dissolution on the poly-p-phenylene benzobisoxazole fiber, and uniformly stirring to obtain fiber slurry; pouring into a mould, spreading and soaking in an exchange solvent, and deacidifying to obtain a colloidal block; and (3) rapidly desolventizing and drying the colloidal block to finally obtain the poly-p-phenylene benzobisoxazole porous membrane.
In the technical scheme, the mass percentage of the poly-p-phenylene benzobisoxazole fiber in the fiber slurry is 0.1-10%.
In the above technical scheme, the acid-soluble solvent is one or more of polyphosphoric acid, alkyl sulfonic acid, fluorine-containing carboxylic acid and sulfuric acid.
In the technical scheme, after the fiber slurry is subjected to ultrasonic degassing treatment, the fiber slurry is poured into a die to be spread.
In the technical scheme, after the fiber slurry is poured into a mold, standing and spreading are performed, and then the exchange solvent is poured into the mold for soaking.
In the above technical scheme, the exchange solvent is one or more of deionized water and an alcohol organic solvent.
In the above technical solution, the rapid solvent removal method includes one or more of extrusion, rolling and vacuum filtration.
In the technical scheme, the drying is naturally dried at 0-40 ℃.
In another aspect, the invention also comprises a micro-short circuit prevention and heat resistance composite membrane, which comprises the polyparaphenylene benzobisoxazole porous membrane and a composite coating attached to one side or both sides of the polyparaphenylene benzobisoxazole porous membrane, wherein the composite coating is an organic and/or inorganic coating.
In the technical scheme, the total thickness of the membrane of the composite membrane is 8-40 mu m; the polyparaphenylene benzobisoxazole porous membrane is formed by three-dimensionally assembling nano fibers, has the thickness of 3-20 mu m and is adjustable, the pore diameter of 50-400nm and is uniformly distributed, and the porosity of 30-85%; the single layer thickness of the composite coating is 3-10 mu m, the pore diameter is 100-400nm, the distribution is uniform, and the porosity is 35-85%.
In the above technical solution, the composite coating layer includes one or more of inorganic particles, phase change material, and binder.
In the technical scheme, the inorganic particles comprise one or more than one of nano-scale boron nitride, carbon nitride, silicon nitride, aluminum nitride, titanium nitride, boron carbide, silicon carbide, zirconium carbide, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, vermiculite, montmorillonite, boehmite, hydrotalcite, barium titanate, barium sulfate and calcium carbonate in any proportion, and the average particle size is 50-800nm.
The phase change material comprises one or more of paraffin, polyvinyl alcohol, polystyrene, polyacrylonitrile, polyethylene oxide, polyethylene, polypropylene, polyacrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, ethylene-vinyl acetate copolymer and polyethylene-rubber copolymer.
The binder comprises one or more of carboxymethyl cellulose, polymethyl methacrylate, polyvinylidene fluoride, styrene-butadiene rubber, polyethylene oxide and polyvinylpyrrolidone.
In another aspect of the invention, the method for preparing the micro-short circuit-proof heat-resistant composite membrane comprises the following steps:
dispersing one or more of inorganic particles and phase change materials and a binder into a solvent, uniformly coating the solvent on one or both sides of a polyparaphenylene benzobisoxazole porous membrane, and drying to obtain the composite membrane.
The solvent comprises one or more of deionized water, acetone, butanone, isopropanol, cyclohexanone, butanol, ethyl acetate, cyclohexane, toluene, xylene, N-dimethylformamide, N-dimethylacetamide, methyl ethyl ketone, N-methylpyrrolidone and dimethyl sulfoxide.
The coating mode comprises one of dip-coating method, spraying, knife coating, roller coating and slit coating.
In another aspect of the invention, the poly-p-phenylene benzobisoxazole porous membrane or the micro-short circuit prevention heat-resistant composite membrane is used as a battery membrane in a battery.
In another aspect of the invention, a high safety battery wherein the separator is a porous membrane of poly-p-phenylene benzobisoxazole or the micro-short circuit resistant and heat resistant composite separator.
The high-safety battery is a metal secondary battery, which is a secondary battery directly using one or more of metal lithium, sodium, potassium, magnesium, aluminum, and zinc as a negative electrode.
Compared with the prior art, the invention has the beneficial effects that:
1. the poly (p-phenylene benzobisoxazole) porous membrane prepared by the method has a flat surface, and is convenient to uniformly coat a coating on the surface; the surface and the internal pore canal are rich, the pore diameter and the gap are adjustable, the electrolyte wettability is good, and the ionic conduction can be satisfied; has excellent mechanical properties and excellent heat resistance, and can prevent micro-short circuit and thermal runaway of the battery.
2. The micro-short circuit-proof high temperature-resistant composite membrane comprises a polyparaphenylene benzobisoxazole porous membrane and an organic and/or inorganic composite coating attached to one side or two sides of the polyparaphenylene benzobisoxazole porous membrane. The porous membrane of poly (p-phenylene benzobisoxazole) maintains the characteristics of rigid supporting function, no thermal shrinkage and high decomposition temperature, so that the composite membrane inherits the characteristics of the porous membrane. The organic and/or inorganic coating is coated on the polyparaphenylene benzobisoxazole porous membrane, so that the problem of chemical incompatibility of the polyparaphenylene benzobisoxazole porous membrane and the electrode material is solved. Meanwhile, when the local temperature rise of the battery occurs, the heat conducting inorganic particles can play a role in rapidly radiating heat, and the temperature difference inside the battery can be reduced. When the temperature of the battery continuously rises, the phase change material contained in the composite layer is softened, melted or swelled to block the original ion channel, so that the battery is prevented from continuously working, and the thermal runaway of the battery can be prevented.
3. The size of the porous membrane of poly-p-phenylene benzobisoxazole and the micro-short circuit prevention high temperature resistant composite membrane prepared by the invention is adjustable, the process is simple, the condition is mild, and the method is suitable for industrial batch production.
Drawings
Fig. 1 is a plan scanning electron micrograph of a porous membrane of poly (p-phenylene benzobisoxazole) of example 1.1 of the present invention.
Fig. 2 is a cross-sectional scanning electron micrograph of a composite separator according to example 1.2 of the present invention.
Fig. 3 is a schematic diagram illustrating the structure and function of the composite separator according to example 1.2 of the present invention.
FIG. 4 is the thermogravimetric results of the composite separator of example 1.2 and the separator of comparative example 2 of the present invention.
FIG. 5 is the thermal crimping results of the composite separator of example 1.2 and the separator of comparative example 2 of the present invention.
FIG. 6 is a graph of the composite separator of example 1.2 and the porous membrane of example 1.1 of the poly (p-phenylene benzobisoxazole) at 0.5mV s -1 The current at the sweep rate varies with the voltage.
Fig. 7 is a charge-discharge curve of the lithium ion battery of example 1.2 according to the present invention at 27 ℃.
Fig. 8 is a charge-discharge curve of the lithium ion secondary battery corresponding to the composite separator of example 1.2 of the present invention at 60 ℃.
Fig. 9 is charge and discharge curves of the lithium metal secondary battery corresponding to the composite separator of example 1.2 of the present invention at different temperatures.
Fig. 10 is a cycle stability result at a temperature of 60 c for the composite separator according to example 2 of the present invention.
Fig. 11 is a charge-discharge curve of the composite separator according to example 3 of the present invention at normal temperature corresponding to the lithium symmetric battery.
Fig. 12 is a graph showing the impedance result of the composite separator according to example 4 of the present invention after heat preservation at 200 ℃.
Fig. 13 is a charge-discharge curve at normal temperature of the zinc metal secondary battery of example 5 of the present invention.
Fig. 14 is charge and discharge curves of the lithium metal secondary battery corresponding to the separator of comparative example 2 according to the present invention at different temperatures.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
Example 1.1
Preparing a polyparaphenylene benzobisoxazole porous membrane:
step 1: methane sulfonic acid and trifluoroacetic acid are mixed according to the volume ratio of 1:15 are mixed and stirred for 10 minutes to prepare a mixed solvent. Adding the poly (p-phenylene benzobisoxazole) fiber into the mixed solvent, and stirring for 5 hours at room temperature to obtain poly (p-phenylene benzobisoxazole) slurry with the mass percentage of 1%.
Step 2: and (3) carrying out ultrasonic treatment on the obtained poly (p-phenylene benzobisoxazole) slurry for 10 minutes to carry out degassing treatment, pouring the poly (p-phenylene benzobisoxazole) slurry into a die, spreading and standing for 10 minutes, pouring deionized water into the die, soaking for 4 hours, and replacing the deionized water for three times to finally obtain the poly (p-phenylene benzobisoxazole) colloidal block.
Step 3: and compacting and dehydrating the poly (p-phenylene benzobisoxazole) colloidal block at normal temperature, and drying the poly (p-phenylene benzobisoxazole) colloidal block in a drying environment at 40 ℃ to finally obtain the flat poly (p-phenylene benzobisoxazole) porous membrane.
The above-mentioned polyparaphenylene benzobisoxazole film is flat and porous as is clear from the scanning electron micrograph of fig. 1. The porous film was tested to have a thickness of about 6 μm and a pore size of 50-100nm.
Example 1.2
Preparing a micro-short circuit-proof high-temperature-resistant composite diaphragm:
step 1: the preparation method comprises the following steps of (1) mixing boron nitride nanosheets, polyvinylidene fluoride and N-methylpyrrolidone according to a mass ratio of 4:1:20 and stirred at 60 ℃ for 3 hours to prepare an organic-inorganic coating slurry.
Step 2: and uniformly coating the organic-inorganic coating slurry on one side of the poly (p-phenylene benzobisoxazole) porous membrane by using a coating machine, and drying at 60 ℃ to obtain the poly (p-phenylene benzobisoxazole) based composite membrane with the boron nitride-polyvinylidene fluoride coating on one side.
Step 3: and uniformly coating the organic-inorganic coating slurry on one side of the membrane by using a coating machine, and drying to obtain the poly-p-phenylene benzobisoxazole composite membrane with the boron nitride-polyvinylidene fluoride coating on both sides.
The sandwich structure of the coating-polyparaphenylene benzobisoxazole porous membrane-coating is clearly seen from the scanning electron micrograph of fig. 2. The composite separator was tested to have a thickness of about 15 μm and a porosity of 50%.
A schematic diagram of the structure and function of the battery separator of this example is shown in fig. 3, in which boron nitride nanoplatelets are bonded to both sides of a polyparaphenylene benzobisoxazole porous membrane by the binder polyvinylidene fluoride. The polyvinylidene fluoride can swell and block ion channels at high temperature besides the binding effect, and plays a role in reaching a high Wen Bikong. The boron nitride nano-sheets are lapped through the sheets to provide a heat conduction path, so that the effects of uniform temperature and rapid cooling are achieved. The porous membrane of poly (p-phenylene benzobisoxazole) is used as a framework, so that the heat resistance and the heat stability of the whole membrane are ensured.
Example 1.3
Thermal stability test of composite separator prepared in example 1.2:
the thermal stability of the composite membrane was tested by thermogravimetric analysis, and fig. 4 shows the thermal weight of the composite membrane, and it can be seen that polyvinylidene fluoride in the coating is thermally decomposed at about 500 ℃ and poly (p-phenylene benzobisoxazole) in the main skeleton is thermally decomposed at about 700 ℃.
The composite separator was tested for contractability at various temperatures and FIG. 5 is a graph of the heat-shrink fatigue rate of the composite separator, and it can be seen that the composite separator still maintains zero contractability at 350 ℃.
Example 1.4
Electrochemical stability test of the composite separator prepared in example 1.2:
the electrochemical stability of the diaphragm is tested by using an electrochemical workstation, stainless steel is used as an anode, metallic lithium is used as a cathode, commercial ether electrolyte is used as electrolyte, and the diaphragm adopts the composite diaphragm. FIG. 6 is a graph at 0.5mV s -1 The current at the sweep rate varies with the voltage. It can be seen that the separator maintains good electrochemical stability over the electrolyte stabilizing voltage range.
Example 1.5
Example 1.2 composite separator assembled lithium metal symmetric battery and electrochemical test:
and the composite diaphragm is used as a diaphragm to be assembled into a lithium metal symmetrical battery, wherein both electrodes adopt lithium sheets, and the electrolyte adopts commercial ether electrolyte.
The battery is subjected to constant-current charge and discharge test by using a charge and discharge instrument, and the current density is 1.0mA cm -2 The test cut-off capacity is 1.0mAh cm -2 . Fig. 7 is a charge-discharge curve for a corresponding battery at a temperature of 27 c, and it can be seen that the voltage remains stable and the polarization voltage is small after 1600 hours of battery cycling. Fig. 8 is a charge-discharge curve for a corresponding battery at a temperature of 60 c, and it can be seen that the voltage remains stable and the polarization voltage is small after 1300 hours of battery cycling.
Example 1.6
The composite separator assembly lithium metal secondary battery prepared in example 1.2:
the composite diaphragm is used as a diaphragm to assemble a lithium metal secondary battery, wherein a ternary nickel cobalt manganese (LiNi0.8Co0.1Mn0.1) is used as an electrode of an active substance in the positive electrode, a lithium sheet is used as an electrode in the negative electrode, and commercial ester electrolyte is used as electrolyte.
Example 1.7
Electrochemical test and thermal safety test of the metal secondary battery prepared in example 1.6:
and carrying out constant-current charge and discharge test on the battery by using a charge and discharge instrument, wherein the test temperatures are respectively. Fig. 9 is a charge-discharge curve of the battery at different temperatures. It can be seen that the separator can be operated cyclically at 140 ℃, thermal runaway does not occur, the battery is disassembled, and the separator is not found to be tired.
Example 2
The only difference from example 1 is that the polyparaphenylene benzobisoxazole porous membrane prepared in this example was prepared using polyphosphoric acid as the acid-soluble solvent.
Through testing, the thickness of the obtained polyparaphenylene benzobisoxazole porous membrane is about 5 mu m, and the aperture is 150-200nm. Further, the thickness of the composite separator was about 12. Mu.m, and the porosity was 60%.
The composite diaphragm prepared by the method is used as a diaphragm of a lithium metal secondary battery, through an electrochemical test and a thermal safety test, the composite diaphragm can prevent the growth of negative electrode lithium dendrites, and fig. 10 is a cycle charge-discharge curve of the corresponding battery at the temperature of 60 ℃, and the lithium metal secondary battery still maintains good cycle performance at high temperature and cannot cause thermal runaway.
Example 3
The difference from example 1 is that the micro short circuit prevention high temperature resistant composite membrane prepared in this example is characterized in that the coating slurry is prepared from barium titanate, polyvinylidene fluoride and N-methyl pyrrolidone according to the mass ratio of 4:1: 20. And only one side of the film is coated to obtain the poly (p-phenylene benzobisoxazole) based composite film with the barium titanate-polyvinylidene fluoride coating on one side.
The composite separator was tested to have a thickness of about 9 μm and a porosity of 65%. The composite diaphragm prepared by the method is used as a diaphragm of a lithium metal secondary battery, wherein one side with a coating is attached to a negative electrode, the composite diaphragm can prevent the growth of negative electrode lithium dendrite through an electrochemical test and a thermal safety test, and fig. 11 is a charge-discharge curve corresponding to a lithium symmetrical battery, and the current density is 1.0mA cm -2 The test cut-off capacity is 1.0mAh cm -2 . The lithium metal secondary battery maintains good cycle performance at high temperature without thermal runaway. The battery was disassembled and no separator was found to be drowsy.
Example 4
The difference from example 1 is only that the composite separator prepared in this example was used to assemble a lithium ion secondary battery, and graphite was used as the negative electrode of the active material.
The lithium ion secondary battery was tested to have been incubated at a high temperature of 200 ℃ for 10 minutes without thermal runaway. As can be seen from the graph of the battery impedance after incubation, the internal resistance increases, and self-disconnection occurs without ion conduction. The battery was disassembled and no separator was found to be drowsy.
Example 5
In the embodiment, the polyparaphenylene benzobisoxazole porous membrane prepared in the embodiment 1.1 is used as a diaphragm to assemble a zinc metal secondary battery, the positive electrode adopts zinc vanadate as an electrode of an active substance, the negative electrode adopts a zinc sheet as an electrode, and the electrolyte is 2mol/L zinc sulfate solution. As tested, the zinc metal secondary battery has good electrochemical properties as shown in fig. 13, which is a charge-discharge curve of the corresponding battery at normal temperature of 25 ℃. And the negative electrode was found to have no dendrite after disassembly of the battery.
Comparative example 1
This comparative example uses the polyparaphenylene benzobisoxazole porous membrane prepared in example 1.1 as a separator. After electrochemical stability test, it is found that the pure poly (p-phenylene benzobisoxazole) porous membrane undergoes an electroreduction reaction at about 0.5V (relative to lithium metal), as shown in fig. 6, a significant reduction peak is generated, indicating that the pure poly (p-phenylene benzobisoxazole) porous membrane has electrochemical instability with lithium metal.
Comparative example 2
Other conditions were the same as in example 1, except that a commercial polypropylene separator was used as the separator. After thermal stabilization testing, it was found that the polypropylene separator underwent explicit thermal decomposition at 380 ℃ temperature (fig. 4), and was susceptible to thermal crimping (fig. 5), and failed to operate at high temperature (fig. 14).
In conclusion, the micro-short circuit prevention heat-resistant composite diaphragm is prepared by simple casting film forming, coating and drying, has a simple preparation process and is suitable for mass production. The composite diaphragm has the advantages of excellent electrochemical stability, dendrite resistance effect, high mechanical property, good ion transmission performance, fast heat conduction, high temperature resistance, closed pore at high temperature and the like, and can prolong the cycle life and improve the safety performance of a battery.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (10)

1. A polyparaphenylene benzobisoxazole porous membrane prepared by the steps of: carrying out acid dissolution on the poly-p-phenylene benzobisoxazole fiber, and uniformly stirring to obtain fiber slurry; pouring into a mould, spreading and soaking in an exchange solvent, and deacidifying to obtain a colloidal block; and (3) rapidly desolventizing and drying the colloidal block to finally obtain the poly-p-phenylene benzobisoxazole porous membrane.
2. The porous membrane of poly (p-phenylene benzobisoxazole) of claim 1, wherein the mass percent of poly (p-phenylene benzobisoxazole) fibers in the fiber slurry is 0.1-10%.
3. The polyparaphenylene benzobisoxazole porous membrane of claim 1 wherein the acid-soluble solvent is one or more of polyphosphoric acid, alkyl sulfonic acid, fluorine-containing carboxylic acid, and sulfuric acid;
preferably, the exchange solvent is one or more of deionized water and an alcohol organic solvent.
4. The polyparaphenylene benzobisoxazole porous membrane of claim 1, wherein the rapid desolvation method comprises one or more of extrusion, roll pressing and vacuum filtration, preferably, the drying is naturally dried at 0 to 40 ℃.
5. The micro-short circuit-proof heat-resistant composite membrane is characterized by comprising the polyparaphenylene benzobisoxazole porous membrane and a composite coating attached to one side or both sides of the polyparaphenylene benzobisoxazole porous membrane, wherein the composite coating is an organic and/or inorganic coating.
6. The composite separator of claim 5, wherein the composite separator has an overall film thickness of 8-40 μm; the polyparaphenylene benzobisoxazole porous membrane is formed by three-dimensionally assembling nano fibers, has the thickness of 3-20 mu m and is adjustable, the pore diameter of 50-400nm and is uniformly distributed, and the porosity of 30-85%; the single layer thickness of the composite coating is 3-10 mu m, the pore diameter is 100-400nm, the distribution is uniform, and the porosity is 35-85%.
7. The composite separator of claim 5, wherein the composite coating comprises one or more of inorganic particles, phase change materials, and binders;
preferably, the inorganic particles comprise one or more of nano-scale boron nitride, carbon nitride, silicon nitride, aluminum nitride, titanium nitride, boron carbide, silicon carbide, zirconium carbide, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, vermiculite, montmorillonite, boehmite, hydrotalcite, barium titanate, barium sulfate and calcium carbonate in any proportion, and the average particle size is 50-800nm;
preferably, the phase change material comprises one or more of paraffin, polyvinyl alcohol, polystyrene, polyacrylonitrile, polyethylene oxide, polyethylene, polypropylene, polyacrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, ethylene-vinyl acetate copolymer and polyethylene-rubber copolymer;
preferably, the binder comprises one or more of carboxymethyl cellulose, polymethyl methacrylate, polyvinylidene fluoride, styrene-butadiene rubber, polyethylene oxide and polyvinylpyrrolidone.
8. The method of preparing a composite separator according to claim 5, comprising the steps of:
dispersing one or more of inorganic particles and phase change materials into a solvent, uniformly coating the inorganic particles and the phase change materials on one or both sides of a polyparaphenylene benzobisoxazole porous membrane, and drying to obtain a composite membrane;
preferably, the solvent comprises one or more of deionized water, acetone, butanone, isopropanol, cyclohexanone, butanol, ethyl acetate, cyclohexane, toluene, xylene, N-dimethylformamide, N-dimethylacetamide, methyl ethyl ketone, N-methylpyrrolidone and dimethyl sulfoxide;
preferably, the coating mode comprises one of dip-coating method, spraying, knife coating, roller coating and slit coating.
9. Use of the polyparaphenylene benzobisoxazole porous membrane of claim 1 or the composite separator of claim 5 as a battery separator in a battery.
10. A high-safety battery, wherein the separator is the polyparaphenylene benzobisoxazole porous film as defined in claim 1 or the composite separator as defined in claim 5, preferably the high-safety battery is a metal secondary battery which is a secondary battery directly using one or more of metal lithium, sodium, potassium, magnesium, aluminum and zinc as a negative electrode.
CN202310264509.6A 2023-03-17 2023-03-17 Poly (p-phenylene benzobisoxazole) porous membrane, preparation method and application thereof, composite membrane and battery Pending CN116376280A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117247646A (en) * 2023-08-24 2023-12-19 上海芯密科技有限公司 Fluororubber composite material containing fibers and preparation method and application thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117247646A (en) * 2023-08-24 2023-12-19 上海芯密科技有限公司 Fluororubber composite material containing fibers and preparation method and application thereof

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