KR20200023794A - Seperator for lithium sulfur battery and manufacturing method - Google Patents

Abstract

The present invention relates to a separator for a lithium-sulfur battery, a manufacturing method thereof, and an electrochemical device including the same. According to the present invention, the separator for a lithium-sulfur battery comprises: a porous substrate including a thermoplastic polymer; a carbon-based first conductive filler layer formed on the porous substrate; an anion exchange functional polymer layer including an ionic liquid-based polymer formed on the carbon-based first conductive filler layer; and a carbon-based second conductive filler layer formed on the anion exchange functional polymer layer.

Description

Membrane for Lithium Sulfur Battery and Manufacturing Method Thereof {SEPERATOR FOR LITHIUM SULFUR BATTERY AND MANUFACTURING METHOD}

The present invention relates to a separator for a lithium sulfur battery and a manufacturing method thereof.

As global warming and climate change issues emerge as global issues, the eco-friendly smart energy industry is receiving great attention. Secondary batteries, which are energy storage devices that can be repeatedly charged and discharged and store constant energy and can be reused when desired, are attracting great attention as mobile power sources of the future era. In particular, recently, small-size and light weight of electronic products, electronic devices, communication devices, etc. are rapidly progressing, and as environmental problems arise, demand for improving performance of secondary batteries used as power sources of these products is also increasing. Among them, lithium secondary batteries have received considerable attention as high-performance batteries because of their high energy density and high standard electrode potential.

In particular, a lithium-sulfur (Li-S) battery is a secondary battery that uses a sulfur-based material having an S-S bond (Sulfur-sulfur bond) as a positive electrode active material and uses lithium metal as a negative electrode active material. Sulfur, the main material of the positive electrode active material, is very rich in resources, has no toxicity, and has an advantage of having a low weight per atom. In addition, the theoretical discharge capacity of the lithium-sulfur battery is 1675mAh / g-sulfur, and the theoretical energy density is 2,600Wh / kg, and the theoretical energy density of other battery systems currently being studied (Ni-MH battery: 450Wh / kg, Li- FeS cells: 480 Wh / kg, Li-MnO 2 cells: 1,000 Wh / kg, Na-S cells: 800 Wh / kg) is very high compared to the most promising battery that has been developed to date.

During the discharge reaction of a lithium sulfur battery, an oxidation reaction of lithium occurs at the negative electrode and a sulfur reduction reaction occurs at the positive electrode. During this reaction, sulfur is converted into linear lithium polysulfide (Li ₂ S ₂ , Li ₂ S ₄ , Li ₂ S ₆ Li ₂ S ₈ ) by reduction reaction in S8 of ring structure, and when lithium polysulfide is completely reduced, lithium Sulphide (Li ₂ S) is produced. Discharge behavior of the lithium sulfur battery by the process of reduction to each lithium polysulfide is characterized in that it exhibits a discharge voltage step by step unlike the lithium ion battery.

Among lithium polysulfides such as Li ₂ S ₈ , Li ₂ S ₆ , Li ₂ S ₄ , and Li ₂ S ₂ , in particular, lithium polysulfides (Li ₂ S _x , usually x> 4) having a high oxidation number of sulfur are used in a hydrophilic electrolyte solution. Easily melts Lithium polysulfide dissolved in the electrolyte is diffused away from the positive electrode where lithium polysulfide is formed due to the difference in concentration. The lithium polysulfide eluted from the positive electrode is lost out of the positive electrode reaction region, so that stepwise reduction to lithium sulfide (Li ₂ S) is impossible. That is, since lithium polysulfide, which is present in the dissolved state outside the positive electrode and the negative electrode, cannot participate in the charge / discharge reaction of the battery, the amount of sulfur material participating in the electrochemical reaction at the positive electrode decreases, and eventually lithium-sulfur It is a major factor causing a decrease in the charge capacity and energy of the battery.

In order to solve the above problems, various researches are in progress, and related prior arts are disclosed in Korean Patent Laid-Open Publication No. 10-2018-0060252 (Polysulfide Adsorption Membrane, Separation Membrane, Lithium-Sulfur Battery and Manufacturing Method Thereof). ), Korean Patent Laid-Open Publication No. 10-2017-0090294 (a separator for a lithium-sulfur battery having a composite coating layer containing polydopamine, a manufacturing method thereof and a lithium-sulfur battery comprising the same), but the production process is complicated, There is a disadvantage that the thickness is too thick or difficult to adjust, it is difficult to apply to various fields.

The present invention is to solve the above problems, a porous substrate comprising a thermoplastic polymer, a carbon-based first conductive filler layer formed on the porous substrate, the ionic liquid-based polymer formed on the carbon-based first conductive filler layer It provides an anion exchange functional polymer layer comprising a and a carbon-based second conductive filler layer formed on the anion exchange functional polymer layer, to provide a separator for a lithium sulfur battery.

More specifically, the separator for lithium sulfur batteries may provide an excellent separator for lithium sulfur batteries having a uniform pore structure and functionality through a double electrospinning technique.

However, the problem to be solved by the present invention is not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A separator for a lithium sulfur battery according to an embodiment of the present invention includes a porous substrate including a thermoplastic polymer, a carbon-based first conductive filler layer formed on the porous substrate, and an ionic liquid formed on the carbon-based first conductive filler layer. An anion exchange functional polymer layer comprising a base polymer and a carbon-based second conductive filler layer formed on the anion exchange functional polymer layer.

According to one embodiment of the invention, the porous substrate, polyethylene, polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polypropylene, polyetherimide, polyvinyl Alcohol, polyethylene oxide, polyacrylic acid, polyvinylpyrrolidone, agarose, alginate, polyvinylidene hexafluoropropylene, polyurethane, nylon 6, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, these It may include one selected from the group consisting of derivatives and combinations thereof.

According to one embodiment of the invention, the carbon-based first conductive filler layer and the second conductive filler layer, the conductive polymer impregnated on the crosslinkable polymer, the conductive polymer, carbon nanotubes, graphene, It may include one selected from the group consisting of graphene oxide, reduced graphene oxide, carbon black and combinations thereof.

According to one embodiment of the present invention, the crosslinkable polymer is selected from the group consisting of polyethyleneimine, polyetherimide, glycerol, butanol, polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, and combinations thereof It may be to include.

According to an embodiment of the present invention, the carbon-based first conductive filler layer and the second conductive filler layer may include a crosslinkable polymer and a conductive polymer in a weight ratio of 50:50 to 60:40.

According to an embodiment of the present invention, the anion of the anion exchange functional polymer layer may include bis (trifluoromethylsulfonyl) imide (Bis (trifluoromethylsulfonyl) imide), polysulfide ions, or both. have.

According to one embodiment of the invention, the ionic liquid-based polymer of the anion exchange functional polymer layer, Poly (1-Ethyl-3-methylimidazolium) bis (trifluoromethylsulfonyl) imide (PVIm [TFSI]), Poly (1-Ethyl) -3-methylimidazolium) bis (trifluoromethylsulfonyl) imide (PVIm [Br]), Poly (1-vinyl-3-ethylimidazolium bromide), Poly (2- (methacryloyloxy) ethyl bis (trifluoromethylsulfonyl) imide and combinations thereof It may include one selected.

According to one embodiment of the invention, the thickness of the anion exchange functional polymer layer may be 5 μm to 10 μm.

According to an embodiment of another aspect of the present invention, an electrochemical device includes a separator positioned between an anode, a cathode, the anode and the cathode, and an electrolyte impregnated with the anode, the cathode, and the separator, It includes a separator according to the embodiment described above.

According to another embodiment of the present invention, a method of manufacturing a separator for a lithium sulfur battery may include preparing a first conductive filler solution and a second conductive filler solution by mixing a conductive polymer, a crosslinkable polymer, and a solvent, respectively. Preparing an anion exchange functional polymer layer composition comprising an ionic liquid-based polymer, spinning the first conductive filler solution on a porous substrate to form a first conductive filler layer, on the first conductive filler layer Stacking an anion exchange functional polymer composition to form an anion exchange functional polymer layer and spinning a second conductive filler solution on the anion exchange functional polymer layer to form a second conductive filler layer.

According to an embodiment of the present invention, in the step of preparing the first conductive filler solution and the second conductive filler solution, the spinning rates of the crosslinkable polymer and the conductive polymer are 1 μl / min to 5 μl / min and 50 μl, respectively. / min to 80 μl / min.

According to one embodiment of the invention, at least one of the spinning of the first conductive filler solution and the spinning of the second conductive filler solution, the stack of the anion exchange functional polymer layer, the dual electrospinning, dual electrospray or dual spray It may be to use.

According to one embodiment of the invention, the solvent is N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone), water, isopropyl alcohol, dimethylformamide (N, N-dimethylformamide), dimethyl Acetamide (N, N-dimethylacetamide), methylpyrrolidone (N, N-Methylpyrrolidone) deionized water, isopropyl alcohol (iso-propylalcohol), butanol, ethanol, hexanol ), Acetone (Acatone), dimethylformamide (N, N-dimethylformamide), sulfuric acid, nitric acid, 2-amino-4-hydroxy-6-methyl-pyrimidine (2-amino-4-hydroxy-6-methyl- pyrimidine (AHMP)), toluene 2,4-diisocyanate and N, N-dimethylacetamide (DMAc) and combinations thereof It may include one selected.

The present invention, an anion exchange functional polymer layer comprising a porous substrate comprising a thermoplastic polymer, a carbon-based first conductive filler layer formed on the porous substrate, an ionic liquid-based polymer formed on the carbon-based first conductive filler layer And a carbon-based second conductive filler layer formed on the anion exchange functional polymer layer, to provide a separator for a lithium sulfur battery.

More specifically, in order to suppress elution of polysulfide and improve performance, a double layer electrospinning technique is used to form a functional layer of a sandwich structure on an existing separator, thereby suppressing elution of polysulfide by an anion exchange reaction. It is possible to provide a lithium sulfur battery of excellent performance.

1 is a diagram showing a separator of a sandwich structure manufactured according to an embodiment of the present invention.
Figure 2 is a diagram showing the manufacturing process of the separator prepared according to an embodiment of the present invention.
Figure 3 is a top and bottom photo of the separator prepared in accordance with an embodiment of the present invention.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. However, various changes may be made to the embodiments so that the scope of the patent application is not limited or limited by these embodiments. It is to be understood that all changes, equivalents, and substitutes for the embodiments are included in the scope of rights.

The terminology used herein is for the purpose of description and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

In addition, in the description with reference to the accompanying drawings, the same components will be given the same reference numerals regardless of the reference numerals and duplicate description thereof will be omitted. In the following description of the embodiment, if it is determined that the detailed description of the related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted.

When an element or layer is represented as "on", "connected to" or "coupled to" another element or layer, this is directly another element or layer It may be understood that the layers may be present, connected or combined, or there may be intervening elements and layers.

Hereinafter, a separator for a lithium sulfur battery of the present invention and a manufacturing method thereof will be described in detail with reference to Examples and drawings. However, the present invention is not limited to these embodiments and drawings.

A separator for a lithium sulfur battery according to an embodiment of the present invention includes a porous substrate including a thermoplastic polymer, a carbon-based first conductive filler layer formed on the porous substrate, and an ionic liquid formed on the carbon-based first conductive filler layer. An anion exchange functional polymer layer comprising a base polymer and a carbon-based second conductive filler layer formed on the anion exchange functional polymer layer.

According to one side, the lithium sulfur battery may have an energy density of about 4 times or more compared to a lithium ion battery, and among the components constituting the lithium sulfur battery, the separator may be in direct contact with the sulfur electrode. .

According to one side, the lithium sulfur battery separator may be carbonaceous material-coated separators or non-carbon-based material coated separators, preferably, carbon-based material coated separators.

According to one side, the carbon-based material of the carbon-based material coating separator not only physically prevents the dissolution of lithium polysulfide, but also serves to chemically reactivate the eluted lithium polysulfide (shuttle effect) The substance is not particularly limited as long as it can be effectively restrained.

According to one side, the carbon-based material coating separator may be coated on one surface of the separator to form a fine pore structure, and the lithium polysulfide may be effectively adsorbed due to the high surface area of the separator.

According to one side, the carbon-based material coating separator may be to ensure excellent battery characteristics due to the improved interfacial contact characteristics of the sulfur electrode.

According to one side, the thermoplastic polymer, polyethylene, polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polypropylene, polyetherimide, polyvinyl alcohol, polyethylene Oxides, polyacrylic acid, polyvinylpyrrolidone, agarose, alginate, polyvinylidene hexafluoropropylene, polyurethane, nylon 6, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, derivatives thereof and their It may include one selected from the group consisting of a combination, preferably, may be polyethylene (PE).

According to one side, the ionic liquid of the ionic liquid-based polymer, the melting point of the organic / inorganic salt composed of a cationic anion may be electrochemically stable with a material of 100 ℃ or less.

According to one side, the ionic liquid can be utilized as a functional polymer material as a green solvent that can be reused with very low vapor pressure, flame retardancy and high solubility to a specific material, and the same as the ionic liquid Synthetic polymer materials including structures may be referred to as ionic liquid-based polymers (poly (ionic liquids), PILs).

According to one side, the ionic liquid-based polymer, the polymer material itself contains an ionic functional group, and has a charge on the polymer chain, and exhibits ion conductivity by the action of the opposite charge ions paired with the charge However, the addition of additional salts may not be necessary.

According to one side, the ionic liquid-based polymer, the polymer of the ABC block copolymer type or a block copolymer capable of hydrogen bonding and the ion gel using a homopolymer, poly (vinylidene fluoride hexafluoropropylene), P (VDF-HFP ) And poly (vinylidenefluoride trifluoroethylene), ionic gel using phase separation of P (VDFTrFE) polymer crystals, and the like. The ionic liquid-based polymer has a ionic conductivity of 10 ^-3 S / cm, 1 to 10 μF. Capacities of / cm ² , excellent electrochemical stability of 4-7 V, which enables the implementation of telechemical transistors with low operating voltages of several V or less, drive frequency of 10 kHz or more, and the fabrication of devices using them. .

According to one embodiment of the invention, the porous substrate, polyethylene, polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polypropylene, polyetherimide, polyvinyl Alcohol, polyethylene oxide, polyacrylic acid, polyvinylpyrrolidone, agarose, alginate, polyvinylidene hexafluoropropylene, polyurethane, nylon 6, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, these It may include one selected from the group consisting of derivatives and combinations thereof.

According to one side, the porous substrate may preferably be polyethylene.

According to one side, the polyethylene is a kind of polyolefin, low reactivity with a carbonate-based organic solvent used as an electrolyte of a lithium secondary battery (electrochemically stable), and may be inexpensive.

According to one side, the porous substrate including the polyethylene, may be prepared by a dry method or a wet method, preferably a substrate prepared by a dry method having a slit (slit) pore structure.

According to one side, in order to compensate for the electrolyte wetting problem due to the inherent hydrophobic properties of the porous substrate including the polyethylene, it is also possible to introduce a polar functional group on the surface of the separator through ultraviolet irradiation, electron beam irradiation or plasma treatment, preferably By introducing a coating layer in the form of a sandwich structure of the first conductive filler layer, the anion exchange functional polymer layer and the second conductive filler layer having a porous net structure can be prepared composite membrane.

According to one embodiment of the invention, the carbon-based first conductive filler layer and the second conductive filler layer, the conductive polymer impregnated on the crosslinkable polymer, the conductive polymer, carbon nanotubes, graphene, It may include one selected from the group consisting of graphene oxide, reduced graphene oxide, carbon black and combinations thereof.

According to one side, the conductive polymer of the carbon-based first conductive filler layer and the second conductive filler layer may include a carbon-based material for coating the separator, the conductive polymer physically prevents the elution of lithium polysulfide In addition to preventing, the role of chemically reactivating the eluted lithium polysulfide (Reactivation) can effectively inhibit the shuttle effect.

According to one side, the conductive polymer is coated on one side of the separator to form a fine pore structure, due to the high surface area by the fine pore structure can effectively adsorb lithium polysulfide.

According to one side, the conductive polymer-coated separator may be to ensure excellent battery characteristics due to the improved interface contact characteristics of the electrode.

According to one side, the conductive polymer, preferably carbon nanotubes, the carbon nanotubes may include a single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT) or both And, most preferably, multi-walled carbon nanotubes.

According to one side, the carbon nanotube is a one-dimensional structural material having a large aspect ratio (Aspect ratio), the carbon nanotubes are surrounded by a polymer support when laminated on the membrane, the pore structure is excellent lithium ion This can pass well, effectively suppress the lithium polysulfide elution, and can more effectively stabilize the surface of the lithium negative electrode than other carbon-based conductive polymers.

According to one side, the multi-walled carbon nanotubes, in particular, excellent mechanical properties, easy to manufacture, economically advantageous, can be commercially available in various fields.

According to one side, the multi-walled carbon nanotubes may be functionalized by a quadruple hydrogen bond to improve dispersibility in the crosslinkable polymer matrix.

According to one embodiment of the present invention, the crosslinkable polymer is selected from the group consisting of polyethyleneimine, polyetherimide, glycerol, butanol, polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, and combinations thereof It may be to include.

According to one side, the crosslinkable polymer may be preferably polyetherimide.

According to one side, the polyetherimide is a polymer having a high glass transition temperature, excellent physical and mechanical properties even at high temperature, high strength and high elastic modulus, and excellent moldability, almost no emission of harmful gases during combustion, flame retardancy May have

According to one side, the polyetherimide exhibits stable insulating properties in a wide frequency range and temperature range, excellent resistance to ultraviolet rays or radiation, and excellent heat resistance due to a rigid aromatic backbone.

According to one side, the first conductive filler layer and the second conductive filler layer, preferably may be a composite layer by directly dispersing the multi-walled carbon nanotubes directly on the polyetherimide polymer matrix and then electrospinning.

According to an embodiment of the present invention, the carbon-based first conductive filler layer and the second conductive filler layer may include a crosslinkable polymer and a conductive polymer in a weight ratio of 50:50 to 60:40.

According to one side, depending on the content of the crosslinkable polymer and the conductive polymer, the surface shape, electrical properties and heat resistance of the first conductive filler layer and the second conductive filler layer may be different.

According to one side, the first conductive filler layer and the second conductive filler layer within the mixing ratio range, while having high electrical conductivity, carbon nanotubes are uniformly dispersed in the PEI matrix can have a high reliability.

According to an embodiment of the present invention, the anion of the anion exchange functional polymer layer may include bis (trifluoromethylsulfonyl) imide (Bis (trifluoromethylsulfonyl) imide), polysulfide ions, or both. have.

According to one side, the polysulfide anion is generated during the operation of the Lithium sulfur battery, the eluted polysulfide is repeatedly moved to the opposite electrode causing a shuttle effect, and reacts with the electrode to the electrode interface Forming a non-conductive passivation layer can reduce the amount of sulfur electrodes that can be used.

According to one side, the anion exchange functional polymer layer, preferably for inhibiting the movement of the polysulfide out of the sulfur anode, a sandwich structure laminated between the first conductive filler layer and the second conductive filler layer When introduced into, it is possible to adsorb polysulfide through anion exchange, to desorb the adsorbed polysulfide during charging, to reversibly adsorb and desorb polysulfide, to protect the separator and negative electrode, and to improve the performance of lithium-sulfur battery. .

According to one embodiment of the invention, the ionic liquid-based polymer of the anion exchange functional polymer layer, Poly (1-Ethyl-3-methylimidazolium) bis (trifluoromethylsulfonyl) imide (PVIm [TFSI]), Poly (1-Ethyl) -3-methylimidazolium) bis (trifluoromethylsulfonyl) imide (PVIm [Br]), Poly (1-vinyl-3-ethylimidazolium bromide), Poly (2- (methacryloyloxy) ethyl bis (trifluoromethylsulfonyl) imide and combinations thereof It may include one selected.

According to one side, the ionic liquid-based polymer may be, preferably, Poly (1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (PVIm [TFSI]).

According to one side, the anion exchange functional polymer layer containing the poly (1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (PVIm [TFSI])) may be nanofibers by electrospinning.

According to one embodiment of the invention, the thickness of the anion exchange functional polymer layer may be 5 μm to 10 μm.

According to one side, the anion exchange functional polymer layer in the thickness range can effectively suppress the dissolution of polysulfide.

According to one side, the ionic liquid polymer constituting the anion exchange functional polymer layer, preferably PVIm [TFSI] polymer, when dissolved in a mixed solvent concentration of the polymer solution 20 wt% to 30 wt% And nanofibers having an average diameter of about 100 nm to 500 nm by electrospinning.

According to one side, the nanofibers in the diameter range is dependent on the concentration of the polymer solution, it may have the most uniform distribution at the optimum voltage that the electrospinning occurs most smoothly.

According to an embodiment of another aspect of the present invention, an electrochemical device includes a separator positioned between an anode, a cathode, the anode and the cathode, and an electrolyte impregnated with the anode, the cathode, and the separator, It includes a separator according to the embodiment described above.

According to another embodiment of the present invention, a method of manufacturing a separator for a lithium sulfur battery may include preparing a first conductive filler solution and a second conductive filler solution by mixing a conductive polymer, a crosslinkable polymer, and a solvent, respectively. Preparing an anion exchange functional polymer layer composition comprising an ionic liquid-based polymer, spinning the first conductive filler solution on a porous substrate to form a first conductive filler layer, on the first conductive filler layer Stacking an anion exchange functional polymer composition to form an anion exchange functional polymer layer and spinning a second conductive filler solution on the anion exchange functional polymer layer to form a second conductive filler layer.

According to one side, the crosslinkable polymer of the first conductive filler solution and the second conductive filler solution may be preferably polyetherimide (PEI), the conductive polymer may be a multi-walled carbon nanotube (MWCNT), The solvents are sulfuric acid, nitric acid, N, N-dimethylformamide (DMF), 2-amino-4-hydroxy-6-methyl-pyrimidine (AHMP), toluene 2,4-diisocyanate and N, N-dimethylacetamide (DMAc). It may include one or more selected from the group consisting of.

According to one side, the multi-walled carbon nanotubes may be functionalized as quadruple hydrogen bonding sites, prepared by preparing a large amount of AHMP introduced on the surface.

According to one side, the polyetherimide was stirred at a high temperature in a solvent to prepare a PEI polymer matrix solution, and the multi-walled carbon nanotubes were sonicated in a water solvent to prepare first and second conductive filler solutions. have.

According to one side, the spinning may be electrospinning, the prepared first and second conductive filler solution is put into a syringe and electrospun by applying a voltage to form a fiber web, and then dried in a heat drying oven to remain The solvent can be removed.

According to one side, a method for synthesizing the ionic liquid polymer constituting it in the step of preparing the anion exchange functional polymer layer composition, polymerization-ion exchange or ion exchange from an ionic liquid monomer containing a polymerizable functional group May include polymerization.

According to one side, after spinning the anion exchange functional polymer composition on the first conductive filler layer, and then again spinning a second conductive filler solution to form a functional separator of the sandwich structure with an anion exchange functional polymer layer formed in the middle Can be.

According to an embodiment of the present invention, in the step of preparing the first conductive filler solution and the second conductive filler solution, the spinning rates of the crosslinkable polymer and the conductive polymer are 1 μl / min to 5 μl / min and 50 μl, respectively. / min to 80 μl / min.

According to one side, according to the spinning speed range, it is possible to form a first conductive filler layer and a second conductive filler layer similar to the above-described average diameter range, the Taylor of the polymer solution by electrospinning at the speed The cone is formed stably and can form a more uniform and thin web structure.

According to one embodiment of the invention, at least one of the spinning of the first conductive filler solution and the spinning of the second conductive filler solution, the stack of the anion exchange functional polymer layer, the dual electrospinning, dual electrospray or dual spray It may be to use.

According to one side, the spinning of the first conductive filler solution and the spinning of the second conductive filler solution, lamination of the anion exchange functional polymer layer may be preferably all by double electrospinning, by double electrospinning At this time, the first and second conductive filler layers control the cohesion behavior of the nano-carbon material to significantly improve the dispersibility in the solvent, and due to the mutual attraction due to the similarity of the molecular structure between the materials, the beads It may be possible to manufacture a functional separator that hardly occurs).

According to one embodiment of the invention, the solvent is N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone), water, isopropyl alcohol, dimethylformamide (N, N-dimethylformamide), dimethyl Acetamide (N, N-dimethylacetamide), methylpyrrolidone (N, N-Methylpyrrolidone) deionized water, isopropyl alcohol (iso-propylalcohol), butanol, ethanol, hexanol ), Acetone (Acatone), dimethylformamide (N, N-dimethylformamide), sulfuric acid, nitric acid, 2-amino-4-hydroxy-6-methyl-pyrimidine (2-amino-4-hydroxy-6-methyl- pyrimidine, (AHMP)), toluene 2,4-diisocyanate and N, N-dimethylacetamide (DMAc) and combinations thereof It may include one selected.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

However, the following examples are only for illustrating the present invention, and the contents of the present invention are not limited to the following examples.

EXAMPLE Preparation of Functional Separator for Lithium Sulfur Battery

PEI purchased ULTEM 1000 grade manufactured by Sabic Co. and MWCNTs used multi-walled carbon nanotubes provided by JEIO Co. (Seoul, Korea). Sulfuric acid, nitric acid, N, N-dimethylformamide (DMF), 2-amino-4-hydroxy-6-methyl-pyrimidine (AHMP) and toluene 2,4-diisocyanate (TDI) are available from Aldrich (Seoul, Korea). It was purchased and used, N, N-dimethylacetamide (DMAc) from JUNSEI was used as a solvent.

PEI polymer (1.17 g) was physically stirred at 70 ^° C. for 10 hours in DMAc solvent (5 ml) to prepare a PEI polymer solution. PEI and MWCNTs were sonicated for 1 hour by adding MWCNTs to water together with a dispersant. Each spinning solution was prepared.

PEI and MWCNT spinning solutions were placed in syringes and double electrospun by applying voltage. At this time, the release rates of the PEI and MWCNT solutions were 3 μl / min and 65 μl / min, respectively, to form a fibrous web. The spun solution was rolled at 80 ^° C. and dried for 12 hours in a 60 ^° C. heat-dried oven to completely remove the remaining solvent and complete the first conductive filler layer.

PVdF-HFP (Aldrich. Co.) based polymer was dissolved in acetone (purity 99%, Daejung Chemical Co.) and DMAc (N, N-dimethylacetamide, Daejung Chemical Co.) mixed solvent to prepare PVdF-HFP polymer solution. , PVIm [TFSI] based ionic liquid polymer was also dissolved in acetone (purity 99%, Daejung Chemical Co.) and DMAc (N, N-dimethylacetamide, Daejung Chemical Co.) mixed solvent to prepare PVIm [TFSI] polymer solution It was.

Thereafter, PVdF-HFP and PVIm [TFSI] polymer solutions were respectively placed in a silicide on the first conductive filler layer and electrospun at the same time using a voltage generator to stack anion exchange functional polymer layers.

On the anion exchange functional polymer layer, a second conductive filler layer prepared by the same manufacturing method as the first conductive filler layer was formed by spinning in the same manner.

In summary, the first conductive filler layer with improved pore structure was prepared by simultaneously spinning the PEI and MWCNT solutions prepared on the PE separator. Thereafter, the ionic liquid-based polymer solution and the PVdF-HFP solution serving as the support were also spun at the same time to prepare an anion exchange functional layer having a spider web structure. Thereafter, the aforementioned second conductive filler layer was radiated onto the functional layer to prepare a functional separator having a sandwich structure.

Lithium sulfur battery comprising a functional separator prepared according to the embodiment, the discharge in the ionic liquid-based polymer of the anion-exchange functional polymer layer containing a polymer / ionic liquid-based polymer (Poly (ionic liquid) s) that is the intermediate layer of the sandwich Polysulfide ions, which have the characteristics of anions melted from sulfur anodes, are adsorbed to the polysulfides through anion exchange method, desorbed polysulfides during charging, and reversibly adsorb and desorb polysulfides. It has been found to protect and improve the performance of lithium-sulfur batteries.

In addition, the first and second conductive filler layers above and below the anion exchange functional polymer layer, which is a functional layer, are conductive / porous layers, and have excellent mobility of lithium ions, and improve the utilization efficiency of polysulfide through conductivity, thereby separating membranes and cathodes. It has been found to protect and improve the performance of lithium-sulfur batteries.

The anion exchange functional polymer layer, reversibly adsorption-desorption and desorption of the polysulfide during charge and discharge, and by allowing the movement of lithium ions through the excellent pore structure, the polysulfide to the negative electrode of the lithium sulfur battery is a problem At the same time, smooth movement of lithium ions was achieved.

The first and second conductive filler layers are made of a polymer / carbon structure, and are conductive / porous layers. The upper layer facing the electrode serves as an upper current collector to adsorb and desorb polysulfide. And to improve the utilization efficiency, the lower layer was confirmed to block the polysulfide desorbed from the intermediate layer to the cathode side.

The above description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is represented by the following claims, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof are included in the scope of the present invention.

Claims (13)

A porous substrate including a thermoplastic polymer;
A carbon-based first conductive filler layer formed on the porous substrate;
Anion exchange functional polymer layer comprising an ionic liquid-based polymer formed on the carbon-based first conductive filler layer; And
A carbon-based second conductive filler layer formed on the anion exchange functional polymer layer;
Including,
Separator for lithium sulfur battery. The method of claim 1,
The porous substrate,
Polyethylene, polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polypropylene, polyetherimide, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polyvinylpyrrolidone , Agarose, alginate, polyvinylidene hexafluoropropylene, polyurethane, nylon 6, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, derivatives thereof, and combinations thereof. That is,
Separator for lithium sulfur battery. The method of claim 1,
The carbon-based first conductive filler layer and the second conductive filler layer,
A conductive polymer impregnated on the crosslinkable polymer,
The conductive polymer,
Carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, carbon black, and a combination thereof, including one selected from the group consisting of
Separator for lithium sulfur battery. The method of claim 3,
The crosslinkable polymer,
It includes one selected from the group consisting of polyethyleneimine, polyetherimide, glycerol, butanol, polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone and combinations thereof,
Separator for lithium sulfur battery. The method of claim 3,
The carbon-based first conductive filler layer and the second conductive filler layer,
To include a crosslinkable polymer and a conductive polymer in a weight ratio of 50:50 to 60:40,
Separator for lithium sulfur battery. The method of claim 1,
The anion of the anion exchange functional polymer layer,
Bis (trifluoromethylsulfonyl) imide (Bis (trifluoromethylsulfonyl) imide), including polysulfide ions or both,
Separator for lithium sulfur battery. The method of claim 1,
The ionic liquid-based polymer of the anion exchange functional polymer layer,
Poly (1-Ethyl-3-methylimidazolium) bis (trifluoromethylsulfonyl) imide (PVIm [TFSI]), Poly (1-Ethyl-3-methylimidazolium) bis (trifluoromethylsulfonyl) imide (PVIm [Br]), Poly (1-vinyl- 3-ethylimidazolium bromide), Poly (2- (methacryloyloxy) ethyl bis (trifluoromethylsulfonyl) imide and those containing one selected from the group consisting of a combination thereof,
Separator for lithium sulfur battery. The method of claim 1,
The thickness of the anion exchange functional polymer layer is 5 μm to 10 μm,
Separator for lithium sulfur battery. anode;
cathode;
A separator positioned between the anode and the cathode; And
An electrolyte impregnated in the positive electrode, the negative electrode, and the separator; Including,
The separator,
The separator according to any one of claims 1 to 8,
Electrochemical device. Preparing a first conductive filler solution and a second conductive filler solution by mixing a conductive polymer, a crosslinkable polymer, and a solvent, respectively;
Preparing an anion exchange functional polymer layer composition comprising an ionic liquid based polymer;
Spinning the first conductive filler solution on the porous substrate to form a first conductive filler layer;
Stacking an anion exchange functional polymer composition on the first conductive filler layer to form an anion exchange functional polymer layer; And
Spinning a second conductive filler solution on the anion exchange functional polymer layer to form a second conductive filler layer;
Containing,
Method for producing a separator for lithium sulfur battery. The method of claim 10,
In the preparing of the first conductive filler solution and the second conductive filler solution, the spinning rates of the crosslinkable polymer and the conductive polymer are 1 μl / min to 5 μl / min and 50 μl / min to 80 μl / min, respectively. sign,
Method for producing a separator for lithium sulfur battery. The method of claim 10,
At least one of spinning of the first conductive filler solution, spinning of the second conductive filler solution, and stacking of the anion exchange functional polymer layer,
Using double electrospinning, double electrospraying or double spraying,
Method for producing a separator for lithium sulfur battery. The method of claim 9,
The solvent is N-methyl-2-pyrrolidinone (N-methyl-2-pyrrolidone), water, isopropyl alcohol, dimethylformamide (N, N-dimethylformamide), dimethylacetamide (N, N-dimethylacetamide) , Methyl pyrrolidone (N, N-Methylpyrrolidone) deionized water, isopropyl alcohol (iso-propylalcohol), butanol, ethanol, hexanol, acetone, dimethylform Amide (N, N-dimethylformamide), sulfuric acid, nitric acid, 2-amino-4-hydroxy-6-methyl-pyrimidine (AHMP), toluene 2 , 4-diisocyanate (toluene 2,4-diisocyanate) and N, N-dimethylacetamide (N, N-dimethylacetamide, (DMAc)) and one selected from the group consisting of a combination thereof,
Method for producing a separator for lithium sulfur battery.

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