CN112746389B - Polymer electrospun fiber heterosequence staggered membrane, preparation method and application thereof, and lithium ion battery diaphragm - Google Patents

Polymer electrospun fiber heterosequence staggered membrane, preparation method and application thereof, and lithium ion battery diaphragm Download PDF

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CN112746389B
CN112746389B CN201911056766.0A CN201911056766A CN112746389B CN 112746389 B CN112746389 B CN 112746389B CN 201911056766 A CN201911056766 A CN 201911056766A CN 112746389 B CN112746389 B CN 112746389B
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polymer
electrospun fiber
dispersion
membrane
high molecular
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CN112746389A (en
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夏清华
董江舟
张�杰
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
    • D04H1/541—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/728—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by electro-spinning

Abstract

The invention relates to the field of lithium ion batteries, and discloses a polymer electrospun fiber mixed-order interlaced membrane, a preparation method and application thereof and a lithium ion battery diaphragm, wherein the membrane contains a layer structure, and the layer structure is formed by mutually and alternately interlacing polymer electrospun fibers I and polymer electrospun fibers II carrying inorganic particles, so that the polymer electrospun fibers I and the polymer electrospun fibers II in a single layer structure are interlaced with each other; the polymer electrospun fiber I contains a high molecular polymer A, the polymer electrospun fiber II contains a high molecular polymer B, and the high molecular polymer A and the high molecular polymer B are the same. The lithium ion battery diaphragm provided by the invention has high porosity, high liquid absorption rate, high heat resistance and good ionic conductivity.

Description

Polymer electrospun fiber heterosequence staggered membrane, preparation method and application thereof, and lithium ion battery diaphragm
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a polymer electrospun fiber heterosequence interlaced membrane, a preparation method and application thereof, and a lithium ion battery diaphragm containing the polymer electrospun fiber heterosequence interlaced membrane.
Background
The safety performance of the lithium ion battery diaphragm is that the diaphragm is required to have good thermal dimensional stability and has no obvious deformation in a certain high-temperature environment; the thermal-closed cell has better thermal-closed cell performance, generates thermal-closed cells before the short circuit of the battery, has no obvious loss of mechanical strength, and has higher thermal safety temperature.
The power battery has higher working temperature and more complex dynamic environment, and can explode, burn and the like under unconventional states, namely an abnormal charging and discharging state, abnormal heating and abuse of mechanical conditions, so the thermal safety performance of the power lithium ion battery is particularly important. Under the condition of large current, the lithium ion battery is easy to cause a large amount of lithium dendrites to pierce a battery diaphragm, so that the internal short circuit of the battery causes potential safety hazards.
The lithium ion battery diaphragm which is commercially applied at present is a polypropylene (PP) diaphragm and a Polyethylene (PE) diaphragm, and the diaphragm cannot completely meet the requirements of the increasingly developed power battery market.
The new technology and the new material are used for preparing the new diaphragm, the electrostatic spinning method is an effective technology, and the inorganic material is doped into the spinning solution for electrospinning, so that the use of a binder can be avoided.
Disclosure of Invention
The invention aims to provide a polymer electrospun fiber heterosequence interlaced membrane which is suitable and high in porosity, high in mechanical strength, excellent in heat resistance and excellent in ionic conductivity.
In order to achieve the above object, the present invention provides in a first aspect a hetero-ordered interlaced membrane of polymeric electrospun fibers, which comprises a layer structure formed by co-interlacing polymeric electrospun fibers I and polymeric electrospun fibers II carrying inorganic particles with each other in a hetero-ordered manner, such that the polymeric electrospun fibers I and the polymeric electrospun fibers II in a single layer structure are interlaced with each other; the polymer electrospun fiber I contains a high molecular polymer A, the polymer electrospun fiber II contains a high molecular polymer B, the high molecular polymer A and the high molecular polymer B are the same, and the high molecular polymer A and the high molecular polymer B are selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, polyamide, polyacrylonitrile, ethylene vinyl acetate, polyethylene succinate, polyethylene oxide, polyarylethersulfone ketone, cellulose acetate, polyethylene terephthalate and polybutylene terephthalate.
In a second aspect, the present invention provides a method for preparing the aforementioned hetero-ordered interlaced membrane of electrospun fibers, the method comprising:
(1) mixing a dispersion liquid I containing inorganic particles and a dispersion liquid II containing a high molecular polymer B to obtain a dispersion liquid III;
(2) respectively introducing a dispersion liquid IV containing a high molecular polymer A and the dispersion liquid III into a storage of an electrostatic spinning device for electrostatic spinning to obtain a layer structure formed by a polymer electrospun fiber I and a polymer electrospun fiber II loaded with inorganic particles in a mixed and staggered manner, wherein the polymer electrospun fiber I contains the high molecular polymer A, and the polymer electrospun fiber II contains a high molecular polymer B;
(3) and (3) carrying out hot pressing on the layer structure obtained in the step (2) to obtain the membrane.
The third aspect of the invention provides an application of the polymer electrospun fiber heterosequence interlaced membrane in preparation of a lithium ion battery diaphragm.
The invention provides a lithium ion battery separator containing the polymer electrospun fiber heterosequence interlaced membrane.
The polymer electrospun fiber heterosequence interlaced membrane provided by the invention has the advantages of suitability, higher porosity, high liquid absorption rate and high heat resistance.
The polymer electrospun fiber mixed-order interlaced membrane provided by the invention has dimensional stability at high temperature, small thermal shrinkage and high safety, and is expected to be used for preventing thermal runaway of a battery when the membrane is used for preparing the battery.
The invention can also regulate and control the electrochemical performance and mechanical strength of the membrane by regulating the proportion of polymer types and fibers, and realize excellent ionic conductivity of the obtained membrane so as to meet the application requirement of the polymer electrospun fiber heterosequence interlaced membrane as a lithium ion battery diaphragm.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
As described above, the first aspect of the present invention provides a polymer electrospun fiber hetero-sequence interlaced membrane, which contains a layer structure formed by the polymer electrospun fiber I and the polymer electrospun fiber II loaded with inorganic particles interlaced with each other, so that the polymer electrospun fiber I and the polymer electrospun fiber II in a single layer structure are interlaced with each other; the polymer electrospun fiber I contains a high molecular polymer A, the polymer electrospun fiber II contains a high molecular polymer B, and the high molecular polymer A and the high molecular polymer B are the same; the high molecular polymer A and the high molecular polymer B are selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, polyamide, polyacrylonitrile, ethylene vinyl acetate, polyethylene glycol succinate, polyethylene oxide, polyarylethersulfone ketone, cellulose acetate, polyethylene terephthalate and polybutylene terephthalate.
Preferably, the weight content of the inorganic particles in the polymer electrospun fiber II is 1-40%.
More preferably, the high molecular polymer a and the high molecular polymer B are at least one selected from polyvinylidene fluoride, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene, polyarylethersulfone ketone, and polymethyl methacrylate.
Preferably, in the polymeric electrospun fiber II, the inorganic particles are selected from at least one of an oxide of a group IIA metal, a sulfate of a group IIA metal, a hydroxide of a group IIA metal, an oxide of a group IVB metal, an oxide of a group IIIA metal and silica.
Further preferably, the inorganic particles are selected from at least one of hydrated alumina, magnesia, silica, zirconia, titania, boehmite, barium sulfate, and magnesium hydroxide.
Preferably, the inorganic particles have an average particle diameter of 10 to 400 nm.
Preferably, the average diameter of the polymeric electrospun fiber I and the polymeric electrospun fiber II is 0.5 to 2 μm.
Preferably, the average thickness of the film is 20 to 50 μm. More preferably, the average thickness of the film of the present invention can be controlled by controlling the time during the preparation process according to actual needs.
Preferably, the polymeric electrospun fiber I and the polymeric electrospun fiber II are fibers prepared by an electrospinning method.
In order to obtain better electrical properties of the hybrid interlaced membrane of the polymeric electrospun fibers, according to a preferred embodiment, the weight content of the polymeric electrospun fibers I is less than or equal to the weight content of the polymeric electrospun fibers II in a single layer structure.
In order to obtain better mechanical properties of the polymer electrospun fiber hetero-ordered interlaced membrane, according to another preferred embodiment, the weight content of the polymer electrospun fiber I is larger than that of the polymer electrospun fiber II in a single layer structure.
As previously mentioned, a second aspect of the present invention provides a method of preparing the aforementioned polymeric electrospun fibrous heterosequential interlaced membrane, the method comprising:
(1) mixing a dispersion liquid I containing inorganic particles and a dispersion liquid II containing a high molecular polymer B to obtain a dispersion liquid III;
(2) respectively introducing a dispersion liquid IV containing a high molecular polymer A and the dispersion liquid III into a storage of an electrostatic spinning device for electrostatic spinning to obtain a layer structure formed by a polymer electrospun fiber I and a polymer electrospun fiber II loaded with inorganic particles in a mixed and staggered manner, wherein the polymer electrospun fiber I contains the high molecular polymer A, and the polymer electrospun fiber II contains a high molecular polymer B;
(3) hot-pressing the layer structure obtained in step (2) to obtain the membrane.
Preferably, the flow rates of the dispersion IV and the dispersion III are each independently selected from 1ml/h to 10 ml/h.
Preferably, the pore size of each needle of the electrospinning device is independently 0.3 to 1.0 mm.
The number of needles in the electrospinning device is not particularly limited in the present invention, and may be, for example, 2 to 50 needles, and the diameters of the respective needles may be the same or different.
Preferably, wherein, in the step (2), the operating conditions of the electrostatic spinning include: the spinning voltage is 10kV to 30kV, the receiving distance is 10cm to 40cm, the humidity is 10cm to 65 percent, and the spinning temperature is 15 ℃ to 40 ℃.
Preferably, wherein, in step (3), the hot pressing is performed by a plate type hot press, and the operating conditions of the hot pressing include: the hot pressing temperature is 50-150 deg.C, pressure is 1-10MPa, and hot pressing time is 0.5-10 min.
Preferably, in the method of the present invention, the mass concentration of the inorganic particles in the dispersion I is 10 to 50%, and the mass concentration of the high molecular polymer B in the dispersion II is 10 to 60%.
Preferably, in the method of the present invention, the mixing volume ratio of the dispersion liquid I and the dispersion liquid II is 1:9 to 9: 1.
Preferably, in the process according to the invention, the dispersion III has a solids content of from 5% to 50% by weight.
Preferably, in the method of the present invention, the mass concentration of the dispersion IV is 10% to 60%.
Preferably, in the method of the present invention, the solvent in the dispersion I, the dispersion II, the dispersion IV is each independently selected from at least one of dimethylformamide, acetone, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, N-methylpyrrolidone, trifluoroethanol, trifluoroacetic acid, dimethylacetamide, ethanol, and hexafluoroisopropanol.
The process according to the second aspect of the invention will now be described in detail by way of a particularly preferred embodiment:
(a) dissolving a high molecular polymer A in an organic solvent to prepare a dispersion liquid IV with the mass concentration of 10-60%;
(b) dispersing inorganic particles in an organic solvent to form a dispersion I with the mass concentration of 10-50%; dissolving a high polymer material B in an organic solvent to prepare a dispersion liquid II with the mass concentration of 10-60%; mixing the dispersion liquid II with the dispersion liquid I to obtain a dispersion liquid III;
(c) placing the dispersion IV prepared in the step (a) into an injector of an electrostatic spinning device at a flow rate of 1ml/h-10ml/h, placing the dispersion III prepared in the step (B) into the injector of the electrostatic spinning device at a flow rate of 1ml/h-10ml/h, and performing electrostatic spinning to obtain a layer structure formed by interlacing polymer electrospun fibers I and polymer electrospun fibers II carrying inorganic particles in a mixed sequence, wherein the polymer electrospun fibers I contain a high molecular polymer A, and the polymer electrospun fibers II contain a high molecular polymer B;
(d) and (c) carrying out hot pressing on the layer structure obtained in the step (c), and carrying out hot pressing by using a plate type hot press, wherein the hot pressing temperature is 50-150 ℃, the pressure is 1-10MPa, and the hot pressing time is 0.5-10min, so as to obtain the membrane after hot pressing.
The dispersion liquid II and the dispersion liquid IV of the present invention may be the same or different, and the present invention is not particularly limited thereto as long as the aforementioned requirements of the present invention can be met.
As previously mentioned, the third aspect of the present invention provides the use of the aforementioned polymer electrospun fiber heterosequence interlaced membrane in the preparation of lithium ion battery separator.
As previously mentioned, a fourth aspect of the present invention provides a lithium ion battery separator comprising the aforementioned polymer electrospun fiber heterostructured alternating film.
The pressures (or pressures) described in the present invention are all expressed as gauge pressures unless otherwise specified.
The present invention will be described in detail below by way of examples.
In the following examples, various raw materials used are all common commercial products unless otherwise specified.
The electrospinning apparatus used below was purchased from Beijing Innovation technologies, Inc.
The room temperature described below means 25 ℃. + -. 1 ℃ unless otherwise specified.
Polyvinylidene fluoride (available from Achima, France under the trade designation HSV900)
Polyacrylonitrile (available from carbofuran, Mw 1.5X 10) 5 )
Polyvinylidene fluoride-hexafluoropropylene (available from Arkema, France under the trade designation SL-023)
Polyarylethersulfone ketones (available from Dalibojimo Limited, Mw 1X 10 5 )
Polyamide (available from Nanjing Hongrui plastics Co., Ltd., brand B500F)
Polycaprolactone (available from Jinan Dai handle band science and technology Co., Ltd., Mw 200000)
Cellulose acetate (purchased from Nantong acetate fiber Co., Ltd., intrinsic viscosity 1.65dL/g)
Example 1
(a) Weighing 15g of polyacrylonitrile and 10g of polyvinylidene fluoride-hexafluoropropylene, dissolving in 75g of DMF solvent, stirring at room temperature for 12h until the mixture is uniform and transparent, and obtaining a high molecular polymer solution (dispersion IV) with the mass concentration of 25%;
(b) weighing 4g of Al 2 O 3 Particles having an average particle diameter of 100nm were dispersed in 10g of DMF solvent at 1000rpm for 30min by using a stirrer to obtain a uniform dispersion (dispersion I); weighing 10g of polyacrylonitrile and 10g of polyvinylidene fluoride-hexafluoropropylene, dissolving in 66g of DMF solvent, stirring at room temperature for 12 hours until the mixture is uniform and transparent to obtain uniform dispersion liquid (dispersion liquid II), and adding the dispersion liquid II into the dispersion liquid I to form Al 2 O 3 Particle-high molecular polymer "dispersion (dispersion III, solids content 24 wt%);
(c) placing the dispersion IV prepared in the step (a) into an injector of an electrostatic spinning device, wherein the flow rate is 2 ml/h; placing the dispersion III prepared in the step (b) into an injector of an electrostatic spinning device at a flow rate of 4 ml/h; carrying out electrostatic spinning, wherein the apertures of 4 needles are the same and are 0.3mm, the spinning voltage is 15kV, the receiving distance is 10cm, the humidity is 20%, and the temperature is 20 ℃, so as to obtain a layer structure formed by mutually and alternately interlacing polymer electrospun fibers I (the average diameter is 0.8 mu m) and polymer electrospun fibers II (the average diameter is 1 mu m) loaded with inorganic particles, wherein the weight content of the polymer electrospun fibers I is less than that of the polymer electrospun fibers II;
(d) and (c) carrying out hot pressing on the layer structure obtained in the step (c) by using a plate type hot press, wherein the hot pressing temperature is 70 ℃, the pressure intensity is 3MPa, the hot pressing time is 1min, and the polymer electrospun fiber hybrid staggered membrane is obtained after hot pressing, and the average thickness of the membrane is 25 microns.
Example 2
(a) 10g of PPESK (available from Dalibo Limo Co., Ltd., Mw 1X 10) 5 ) Dissolving the mixture in 90g of tetrahydrofuran/N-methyl pyrrolidone mixed solvent, wherein the volume ratio of tetrahydrofuran to N-methyl pyrrolidone is 3:7, stirring at room temperature for 12h until the mixture is uniform and transparent, and obtaining a high molecular polymer solution (dispersion liquid IV) with the mass concentration of 10%;
(b) weighing 4g of MgO particles with the average particle size of 50nm, adding the MgO particles into 10g of tetrahydrofuran/N-methyl pyrrolidone mixed solvent, wherein the volume ratio of tetrahydrofuran to N-methyl pyrrolidone is 3:7, and dispersing for 60min at 1200rpm by using a stirrer to obtain a uniform dispersion liquid (dispersion liquid I); weighing 16g of polyarylethersulfone ketone, dissolving the polyarylethersulfone ketone in 70g of tetrahydrofuran/N-methylpyrrolidone mixed solvent, wherein the volume ratio of tetrahydrofuran to N-methylpyrrolidone is 3:7, stirring at room temperature for 12h until the mixture is uniform and transparent to obtain a uniform dispersion liquid (dispersion liquid II), and adding the dispersion liquid II into the dispersion liquid I to form a dispersion liquid (dispersion liquid III, the solid content is 20 weight percent) of 'MgO particle-high molecular polymer';
(c) placing the dispersion IV prepared in the step (a) into an injector of an electrostatic spinning device, wherein the flow rate is 4 ml/h; placing the dispersion liquid III prepared in the step (b) into an injector of an electrostatic spinning device, wherein the flow rate is 2 ml/h; carrying out electrostatic spinning, wherein the apertures of 10 needles are the same and are 0.5mm, the spinning voltage is 20kV, the receiving distance is 15cm, the humidity is 30%, and the temperature is 30 ℃, so as to obtain a layer structure formed by mutually and alternately interlacing polymer electrospun fibers I (the average diameter is 0.5 mu m) and polymer electrospun fibers II (the average diameter is 1.3 mu m) loaded with inorganic particles, wherein the weight content of the polymer electrospun fibers I is equal to that of the polymer electrospun fibers II;
(d) and (c) carrying out hot pressing on the layer structure obtained in the step (c) by using a plate type hot press, wherein the hot pressing temperature is 80 ℃, the pressure intensity is 4MPa, the hot pressing time is 1min, and the polymer electrospun fiber hybrid staggered membrane is obtained after hot pressing, and the average thickness of the membrane is 30 micrometers.
Example 3
(a) Weighing 25g of polyvinylidene fluoride, dissolving the polyvinylidene fluoride in 75g of DMF, and stirring at room temperature for 12h until the mixture is uniform and transparent to obtain a high molecular polymer solution (dispersion IV) with the mass concentration of 25%;
(b) 6g of SiO are weighed 2 Particles having an average particle diameter of 100nm were added to 15g of hexafluoroisopropanol solvent, and dispersed at 800rpm for 45min with a stirrer to obtain a uniform dispersion (dispersion I); weighing 24g of polyvinylidene fluoride, dissolving in 55g of DMF solvent, stirring at room temperature for 12h until the mixture is uniform and transparent to obtain uniform dispersion liquid (dispersion liquid II), and adding the dispersion liquid II into the dispersion liquid I to form SiO 2 Particle-high molecular polymer "dispersion (dispersion III, solids content 30 wt%);
(c) placing the dispersion IV prepared in the step (a) into an injector of an electrostatic spinning device, wherein the flow rate is 4 ml/h; placing the dispersion liquid III prepared in the step (b) into an injector of an electrostatic spinning device, wherein the flow rate is 2 ml/h; carrying out electrostatic spinning, wherein the pore diameters of 2 needles are the same and are 0.7mm, the spinning voltage is 28kV, the receiving distance is 25cm, the humidity is 30%, and the temperature is 30 ℃, so as to obtain a layer structure formed by mutually and alternately interlacing polymer electrospun fibers I (the average diameter is 1.5 mu m) and polymer electrospun fibers II (the average diameter is 1.2 mu m) loaded with inorganic particles, wherein the weight content of the polymer electrospun fibers I is larger than that of the polymer electrospun fibers II;
(d) and (c) carrying out hot pressing on the layer structure obtained in the step (c) by using a plate type hot press, wherein the hot pressing temperature is 100 ℃, the pressure intensity is 5MPa, the hot pressing time is 2min, and the polymer electrospun fiber hybrid staggered membrane is obtained after hot pressing, and the average thickness of the membrane is 35 microns.
Example 4
This example was carried out in a similar manner to example 2, except that,
in this example, the high molecular polymers a and B are both polyamides, and the amount of the high molecular polymer a is 10g, the amount of the high molecular polymer B is 16g, and 90g and 70g of formic acid-acetic acid (volume ratio is 1:1) mixed solvent capable of well dissolving polyamide are respectively used to form corresponding high molecular polymer solutions as the dispersion IV and the dispersion II.
The rest is the same as that in the example 2, and the polymer electrospun fiber heterosequence staggered membrane is obtained.
Example 5
This example was carried out in a similar manner to example 3, except that,
in this example, the high molecular polymers a and B are both cellulose acetate, and the amount of the high molecular polymer a is 25g, the amount of the high molecular polymer B is 24g, and 75g and 55g of an N, N-dimethylacetamide/acetone mixed solvent (N, N-dimethylacetamide/acetone volume ratio is 4:6) are respectively used to form corresponding high molecular polymer solutions as the dispersion IV and the dispersion II.
The rest is the same as that in the example 3, and the polymer electrospun fiber heterosequence staggered membrane is obtained.
Comparative example 1
This comparative example was conducted in a similar manner to example 3, except that,
the high molecular polymers a and B in this example are all polycaprolactone, and the amount of the high molecular polymer a is 25g, the amount of the high molecular polymer B is 24g, and 75g and 55g of DMF are respectively adopted to form corresponding high molecular polymer solutions to be respectively used as the dispersion IV and the dispersion II.
The rest is the same as that in the example 3, and the polymer electrospun fiber heterosequence staggered membrane is obtained.
Test example
The performance parameters of the films obtained in the examples were tested by the following specific test methods, and the test results are shown in table 1.
Thickness: measuring the thickness by a micrometer (the precision is 0.01 mm), randomly sampling 5 points on a sample, and averaging;
porosity: the membrane was soaked in n-butanol for 2h and then the porosity (p) was calculated according to the formula:
Figure BDA0002255721990000101
where ρ is 1 And ρ 2 Is the density of n-butanol and the dry density of the membrane, m 1 And m 2 The mass of n-butanol absorbed by the membrane and the mass of the membrane itself;
liquid absorption rate: the membrane was soaked in n-butanol for 12h and then the imbibition rate (P) was calculated according to the formula:
Figure BDA0002255721990000111
wherein, W 2 And W 1 The mass of n-butanol absorbed by the membrane and the mass of the membrane itself;
tensile strength: the tensile strength of the film was tested using the plastic tensile test method of GB 1040-79;
heat shrinkage ratio: the dimensional heat shrinkage was measured using an oven, the sample was heat treated at 150 ℃ for 2h, and then the heat shrinkage (δ) was calculated according to the formula:
Figure BDA0002255721990000112
wherein S is 1 And S 2 Is the area before and after the film heat treatment;
heat resistance temperature: testing the melting point of the shell material by using a differential scanning calorimeter, and determining the approximate range of the heat-resistant temperature; then carrying out heat treatment at different temperatures for 30min, and then testing the porosity, wherein the temperature when the porosity is rapidly reduced is determined as the heat-resistant temperature; the heat-resistant temperature reflects the heat resistance and the thermal safety of the film, and when the heat-resistant temperature is reached, the film cannot work normally;
ionic conductivity: the conductivity of the diaphragm is measured by adopting an electrochemical workstation, and the frequency range of the measurement is 0.001Hz-10 5 Hz, then the conductivity (σ) is calculated according to the formula:
Figure BDA0002255721990000113
wherein σ is the conductivity (S/cm) of the separator, d is the thickness (cm) of the separator, R b Is the bulk resistance (omega) of the separator, and A is the effective area (cm) of the separator in contact with the electrode 2 )。
TABLE 1
Figure BDA0002255721990000114
As can be seen from the results of table 1, the film provided by the present invention has high and suitable porosity, good mechanical properties, good heat shrinkage properties, high heat resistance and good ionic conductivity.
More specifically, the results of comparative example 2 and example 4, and of comparative example 3 and example 5 show that the mechanical properties of the films produced with the polymers of the preferred embodiment of the present invention are superior for the same thickness.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (22)

1. A polymer electrospun fiber heterosequence interlaced membrane comprising a layer structure formed by intermingling polymer electrospun fiber I and polymer electrospun fiber II loaded with inorganic particles such that polymer electrospun fiber I and polymer electrospun fiber II in a single layer structure are interlaced with each other; the high molecular polymer in the polymer electrospun fiber I is a high molecular polymer A, the high molecular polymer in the polymer electrospun fiber II is a high molecular polymer B, the high molecular polymer A and the high molecular polymer B are the same, and the high molecular polymer A and the high molecular polymer B are selected from at least one of polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene, polyarylethersulfone ketone and polymethyl methacrylate;
the average diameter of the polymer electrospun fiber I and the polymer electrospun fiber II is 0.5-2 μm.
2. The membrane of claim 1, wherein the inorganic particles are present in the polymeric electrospun fiber II in an amount of 1-40% by weight.
3. The membrane of claim 1, wherein in the polymeric electrospun fiber II, the inorganic particles are selected from at least one of an oxide of a group IIA metal, a sulfate of a group IIA metal, a hydroxide of a group IIA metal, an oxide of a group IVB metal, an oxide of a group IIIA metal and silica.
4. The membrane according to any one of claims 1 to 3, wherein the inorganic particles are selected from at least one of hydrated alumina, magnesia, silica, zirconia, titania, boehmite, barium sulfate and magnesium hydroxide.
5. A membrane according to any one of claims 1 to 3, wherein the inorganic particles have an average particle size of 10 to 400 nm.
6. A film according to any one of claims 1 to 3 wherein the average thickness of the film is from 20 to 50 μm.
7. The membrane according to any one of claims 1 to 3, wherein the polymeric electrospun fiber I and the polymeric electrospun fiber II are fibers prepared by an electrospinning method.
8. The membrane of any one of claims 1-3, wherein the polymeric electrospun fiber I is present in an amount by weight equal to or less than the amount by weight of the polymeric electrospun fiber II in a single said layer structure.
9. The membrane of any one of claims 1-3, wherein the polymeric electrospun fiber I is present in a greater amount by weight than the polymeric electrospun fiber II in a single said layer structure.
10. A method of preparing the polymeric electrospun fiber heteroordered interlaced membrane of any one of claims 1-9, the method comprising:
(1) mixing a dispersion liquid I containing inorganic particles and a dispersion liquid II containing a high molecular polymer B to obtain a dispersion liquid III;
(2) respectively introducing a dispersion IV containing a high-molecular polymer A and a dispersion III into a storage of an electrostatic spinning device for electrostatic spinning so as to obtain a layer structure formed by polymer electrospun fibers I and polymer electrospun fibers II carrying inorganic particles by staggered mutual disorder, wherein the polymer electrospun fibers I contain the high-molecular polymer A, and the polymer electrospun fibers II contain the high-molecular polymer B;
(3) and (3) carrying out hot pressing on the layer structure obtained in the step (2) to obtain the membrane.
11. The process of claim 10, wherein the flow rates of the dispersion IV and the dispersion III are each independently selected from 1ml/h to 10 ml/h.
12. The method of claim 10, wherein the bore diameter of each needle of the electrospinning apparatus is independently 0.3 to 1.0 mm.
13. The method of claim 10, wherein the operating conditions of electrospinning comprise: the spinning voltage is 10kV to 30kV, the receiving distance is 10cm to 40cm, the humidity is 10cm to 65 percent, and the spinning temperature is 15 ℃ to 40 ℃.
14. The method of any of claims 10-13, wherein the hot pressing is performed by a plate press, and the operating conditions of the hot pressing include: the hot pressing temperature is 50-150 deg.C, pressure is 1-10MPa, and hot pressing time is 0.5-10 min.
15. The method according to any one of claims 10 to 13, wherein the mass concentration of the inorganic particles in the dispersion I is 10% to 50%, and the mass concentration of the high molecular polymer B in the dispersion II is 10% to 60%.
16. The method of any of claims 10-13, wherein the dispersion I and the dispersion II are mixed in a volume ratio of 1:9 to 9: 1.
17. The method according to any one of claims 10 to 13, wherein the dispersion IV has a mass concentration of 10% to 60%.
18. The process according to any one of claims 10 to 13, wherein the solvent in the dispersion I, the dispersion II, the dispersion IV is each independently selected from at least one of dimethylformamide, acetone, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, N-methylpyrrolidone, trifluoroethanol, trifluoroacetic acid, dimethylacetamide, ethanol, and hexafluoroisopropanol.
19. The method according to any one of claims 10 to 13, wherein the flow rates of dispersion III and dispersion IV are controlled so that the weight content of polymeric electrospun fiber I is equal to or less than that of polymeric electrospun fiber II in a single said layer structure.
20. The method according to any one of claims 10-13, wherein the flow rates of dispersion III and dispersion IV are controlled such that the weight content of polymeric electrospun fiber I is greater than that of polymeric electrospun fiber II in a single said layer structure.
21. Use of the polymeric electrospun fiber heterosequence interlaced membrane of any one of claims 1-9 in the preparation of a lithium ion battery separator.
22. A lithium ion battery separator comprising the polymeric electrospun fiber heteroordered interlaced membrane of any one of claims 1-9.
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