KR101802594B1 - Lithium-sulfur battery and method for manufacturing same - Google Patents

Abstract

Preparing a base electrolyte, mechanically mixing the base electrolyte and a carbon material to produce an electrolyte mixture, and separating the electrolyte mixture into a battery structure battery structure according to the present invention.

Description

TECHNICAL FIELD The present invention relates to a lithium sulfur battery,

The present invention relates to a lithium sulfur battery and a method of manufacturing the same, and more particularly, to a lithium sulfur battery manufactured using a self-assembled carbon film containing an electrolyte, and a method of manufacturing the same.

Recently, as governments' eco-friendly policies and greenhouse gas regulations have been fully implemented, the development of high-efficiency eco-friendly energy technologies is accelerating. Also, in order to realize the 21st century power grid represented by the smart grid, there is a growing interest in energy storage technology that can act as a buffer for power generation and consumption. Accordingly, a demand for a lithium secondary battery that can be used as a medium- or large-sized secondary battery such as an electric vehicle and an energy storage system is increasing rapidly.

Therefore, studies on securing stability and high capacity of a lithium secondary battery as applied to electric vehicles and medium and large-sized energy storage devices are being actively conducted.

For example, in International Publication No. WO15005694A1 (Applicant: LG Chem International, International Application No. WO2014KR006195), an electrode slurry mixture layer is applied to one or both surfaces of an electrode current collector to form a first electrode, Based coating layer on the electrode surface by forming a polyurethane-based coating layer on the surface of the electrode by immersing the compound in a coating solution in which the compound is dissolved in a non-aqueous solvent, coating the coating solution, A manufacturing technique of an electrode of a plasma display panel is disclosed.

In order to commercialize an electric vehicle and a medium to large-sized energy storage device, it is necessary to study a method of manufacturing a lithium sulfur battery capable of improving capacity and lifetime characteristics of a lithium sulfur battery having superior capacity characteristics than a lithium ion battery.

International Publication No. WO15005694A1

SUMMARY OF THE INVENTION The present invention provides a lithium sulfur battery having improved lifetime characteristics and a method of manufacturing the same.

Another object of the present invention is to provide a lithium sulfur battery having improved capacity characteristics and a method of manufacturing the same.

 It is another object of the present invention to provide a lithium sulfur battery having improved electrical conductivity and a method of manufacturing the same.

It is another object of the present invention to provide a lithium-sulfur battery having improved ion conductivity and a method of manufacturing the same.

Another object of the present invention is to provide a lithium sulfur battery having a reduced manufacturing cost and a method of manufacturing the same.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above-described technical problems, the present invention provides a method for producing a lithium sulfur battery.

According to an embodiment of the present invention, there is provided a method of manufacturing a lithium sulfur battery, comprising: preparing a base electrolyte; mechanically mixing the base electrolyte and a carbon material to form an electrolyte mixture ), And injecting the electrolyte mixture solution into a battery structure.

According to one embodiment, after the electrolyte mixture solution is injected into the cell structure, at least a part of the base electrolyte in the electrolyte mixture solution is absorbed into the cell structure, And a self-assembly carbon layer containing an electrolyte including the base electrolyte.

According to one embodiment, the mechanical mixing of the base electrolyte and the carbonaceous material may include stirring the base electrolyte and the carbonaceous material.

According to one embodiment, the carbon material may include at least one carbon allotrope.

According to one embodiment, the cell structure may include a cathode, a separator, and an anode, which are stacked in sequence.

According to an embodiment, the step of injecting the electrolyte mixed solution into the cell structure may include injecting the electrolyte mixed solution between the anode and the separator.

According to an embodiment, the self-assembled carbon film containing the electrolyte may be self-assembled into a shape corresponding to the shape of one surface of the anode and the surface of the separator contacting the self-assembled carbon film containing the electrolyte, Lt; / RTI >

In order to solve the above technical problems, the present invention provides a lithium sulfur battery.

According to one embodiment, the lithium sulfur battery includes a cathode containing carbon (C) and sulfur (S), a cathode disposed on the anode, having a shape corresponding to the shape of one surface of the anode, A self-assembly carbon layer containing the electrolyte, a separator on the self-assembled carbon film containing the electrolyte, and an anode containing lithium on the separator.

According to one embodiment, the self-assembled carbon film containing the electrolyte may include at least one carbon allotrope.

According to one embodiment, the self-assembled carbon film containing the electrolyte may contain 3 to 4 mg of the carbon material.

According to one embodiment, the self-assembled carbon film containing the electrolyte includes a first electrolyte surface in contact with one surface of the anode and corresponding to the shape of the one surface of the anode, And a second electrolyte surface corresponding to the shape of the one surface of the separator.

According to one embodiment, when the one surface of the anode has a convex portion, the first electrolyte surface has a concave portion corresponding to the convex portion of the one surface of the anode, and when the one surface of the anode has a concave portion, And the first electrolyte surface may have a convex portion corresponding to the concave portion of the one surface of the anode.

According to an embodiment, the lithium sulfur battery may further include a first electrode layer having a surface roughness of the first electrolyte surface of the self-assembled carbon film containing the electrolyte, a surface roughness of the surface of the second electrolyte layer of the self- May be larger than roughness.

According to an embodiment, the initial shape of the first electrolyte surface and the second electrolyte surface of the self-assembled carbon film containing the electrolyte may include a state in which the cycle of the lithium sulfur battery is kept constant.

According to an embodiment of the present invention, a self-assembly carbon layer containing an electrolyte is prepared by preparing an electrolyte mixture solution containing a carbon material, injecting the electrolyte mixture solution between the positive electrode and the separator of the battery structure, Can be formed. Accordingly, the process time and the process cost of the lithium sulfur battery including the self-assembled carbon film containing the electrolyte can be reduced.

Also, at least a part of the base electrolyte of the electrolyte mixture solution is absorbed into the battery structure, and the self-assembled carbon film containing the electrolyte may be self-assembled into a shape corresponding to the shape of one surface of the anode and one surface of the separator. have. Accordingly, a lithium selenium battery in which the contact area between the anode and the self-assembled carbon film containing the electrolyte and the electrolyte is increased to improve ionic conductivity and electrical conductivity, and a method of manufacturing the same can be provided.

In addition, due to the carbon material contained in the self-assembled carbon film containing the electrolyte, sulfur (S) eluted from the anode can be effectively suppressed, and the electrical conductivity of the battery Can be improved. Accordingly, the capacity and life characteristics of the battery are improved, and a highly reliable lithium-sulfur battery improved in charging and discharging efficiency and a manufacturing method thereof can be provided.

1 is a flowchart illustrating a method of manufacturing a lithium sulfur battery according to an embodiment of the present invention.
2 is a view for explaining a method of producing an electrolyte mixed solution according to an embodiment of the present invention.
FIG. 3 is an enlarged view of FIG. 2 A. FIG.
4 is a view for explaining a lithium sulfur battery manufactured according to an embodiment of the present invention
FIG. 5 is an enlarged view of FIG. 4B.
6 is SEM images of the surface and side surfaces of the bare MWCNT film and the MWCNT-self-assembled carbon film included in the lithium sulfur battery according to Examples and Comparative Examples of the present invention.
7 is FIB-SEM images of the bare MWCNT film and the MWCNT self-assembled carbon film included in the lithium sulfur battery according to the comparative example and the embodiment of the present invention.
FIG. 8 is a TEM (Transmission Electron Microscope) image and electron energy loss spectroscopy (EELS) images of a bare MWCNT film and an MWCNT-self-assembled carbon film included in a lithium selenium battery according to Examples and Comparative Examples of the present invention.
FIG. 9 is a specific capacity graph of a lithium selenium battery including the MWCNT self-assembled carbon film and the bare MWCNT film manufactured according to the embodiment of the present invention and the comparative example according to the voltage according to the current rate.
FIG. 10 is a graph of specific capacity according to an increase in the cycle number of a lithium-sulfur battery manufactured according to the examples and comparative examples of the present invention.
FIG. 11 is a graph showing a specific capacity value according to an increase in the number of battery cycles when the amount of MWCNT contained in the MWCNT-self-assembled carbon film of the lithium sulfur battery manufactured according to the embodiment of the present invention is different.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when an element is referred to as being on another element, it may be directly formed on another element, or a third element may be interposed therebetween. Further, in the drawings, the thicknesses of the films and regions are exaggerated for an effective explanation of the technical content.

Also, while the terms first, second, third, etc. in the various embodiments of the present disclosure are used to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. Thus, what is referred to as a first component in any one embodiment may be referred to as a second component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Also, in this specification, 'and / or' are used to include at least one of the front and rear components.

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises "or" having "are intended to specify the presence of stated features, integers, Should not be understood to exclude the presence or addition of one or more other elements, elements, or combinations thereof.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention.

FIG. 1 is a flow chart for explaining a method of manufacturing a lithium-sulfur battery according to an embodiment of the present invention, FIG. 2 is a view for explaining a method of manufacturing an electrolyte mixed solution according to an embodiment of the present invention, FIG. 4 is a view for explaining a lithium sulfur battery according to an embodiment of the present invention and a method of manufacturing the same, and FIG. 5 is an enlarged view of FIG.

Referring to FIGS. 1 and 2, a base electrolyte 100 is prepared (S100). The base electrolyte 100 may include a non-aqueous electrolyte including lithium salts and an organic solvent. For example, the lithium _{salt, LiTFSI, LiNO 3, LiCl,} LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, LiC (CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic carboxylate lithium, And may include at least any one of them.

For example, the non-aqueous electrolyte containing the organic solvent may be at least one selected from the group consisting of N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylenecarbonate, dimethyl carbonate, diethyl carbonate , Ethylmethyl carbonate, gamma-butylolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3- But are not limited to, dioxolane, 4-methyl-1,3-dioxane, diethyl ether, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, , Dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, methyl pyrophosphate and ethyl propionate May include at least one or more .

According to one embodiment, the base electrolyte 100 may include an organic solid electrolyte or an inorganic solid electrolyte. For example, the organic solid electrolyte may be selected from the group consisting of a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, And a polymer including an acid dissociation group. For example, the inorganic solid electrolyte may be Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ -LiI-LiOH, and Li ₃ PO ₄ -Li ₂ S-SiS _2, and the like.

The base electrolyte 100 may be mechanically mixed with a carbon material 200 to form an electrolyte mixture 120 at step S200. The carbon material 200 may include at least one carbon allotrope. For example, the carbon isotope may be a carbon nanotube (single wall carbon nanotube (SWCNT) or multi wall carbon nanotube (MWCNT)), graphene, graphite graphite, activated carbon, and porous carbon. Also, for example, the mechanical mixing may be stirring. For example, dimethoxy ethane (dimethoxyethane), 1,3- dioxo lane (1,3-dioxolane), LiTFSI ( liyhium bis (trifluoromethane sulfonyl) imide), and lithium nitrate, the containing (LiNO ₃₎ The multi-walled carbon nanotube (MWCNT) is added to the base electrolyte 100 and then stirred at a rate of 300 rpm at room temperature to prepare the electrolyte mixture solution 120.

3, when the base electrolyte 100 includes the carbon nanotubes 205, the base electrolyte 100 is formed in the lattice of the sidewalls of the carbon nanotubes 205, And may be provided in a space surrounded by the nanotubes 205.

Referring to FIGS. 1 and 4, a battery structure 600 is prepared. The battery structure 600 may include a cathode 300, a cathode 400, and a separator 500. The battery structure 600 may include the anode 300, the separator 400, and the cathode 500 in this order.

The anode 300 may comprise sulfur (S) and a conductive material. For example, the conductive material may be at least one selected from the group consisting of graphite (natural graphite, artificial graphite and the like), carbon black (carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, Conductive metal oxide (titanium oxide, etc.), conductive material (polyphenylene derivative, etc.), conductive metal oxide (metal oxide, Or at least one of them.

The anode 300 can be manufactured by mixing the sulfur (S) and the conductive material with a binder and a solvent, coating on the current collector, and drying. For example, the binder may be polyvinylidene fluoride (PVDF), and the solvent may be N-methyl-2-pyrrolidone.

The current collector may be formed of a conductive material. For example, the current collector may be formed of copper, nickel, aluminum stainless steel, or the like. The current collector may be coated with a coating layer for preventing oxidation.

The separator 400 may be formed of a glass fiber, an olefin resin, a fluorine resin (e.g., polyvinylidene fluoride, polytetrafluoroethylene), an ester resin (e.g., polyethylene terephthalate) Or a cellulose-based nonwoven fabric. The separation membrane 400 may be formed of various kinds of materials in addition to the examples described above.

The cathode 500 may include lithium (Li). The negative electrode may be formed of lithium metal or an alloy of lithium and another metal. For example, the cathode 500 includes an alloy of silicon (Si), aluminum (Al), tin (Sn), magnesium (Mg), indium (In), vanadium can do.

The electrolyte mixture solution 120 may be injected into the cell structure 600 (S300). In other words, the electrolyte mixture solution 120 may be injected between the anode 300 and the separator 400 stacked in that order of the cell structure 600. The electrolyte mixture solution 120 injected between the anode 300 and the separator 400 of the cell structure 600 is discharged through a drying process to a self- carbon layer, 150). For example, the electrolyte mixture solution 120 may be injected between the anode 300 and the separator 400 by a nozzle or a needle, and then naturally dried .

At least a portion of the base electrolyte 100 in the electrolyte mixture solution 120 injected between the anode 300 and the separator 400 may be absorbed into the cell structure 600 by the drying process . Accordingly, the self-assembled carbon film 150 containing the carbon material 200 remaining in the electrolyte mixture solution 120 and the electrolyte including the base electrolyte 100 may be formed.

If the content of the carbon material 200 in the self-assembled carbon film 150 containing the electrolyte is less than 3 mg or greater than 4 mg, the specific capacity characteristics of the battery may be deteriorated. Therefore, according to the embodiment of the present invention, the self-assembled carbon film 150 containing the electrolyte may include 3 to 4 mg of the carbon material 200.

The self-assembled carbon film 150 containing the electrolyte has a first electrolyte surface 150a contacting the one surface of the anode 300 and a second electrolyte surface 150b contacting the one surface of the separator 400 second electrolyte surface 150b. A process of forming at least a part of the base electrolyte 100 of the electrolyte mixture solution 120 by the positive electrode 300 and / or the negative electrode 400 to form the self-assembled carbon film 150 containing the electrolyte The first electrolyte surface 150a contacting the one surface of the anode 300 may be selfassembled to have a shape corresponding to the shape of one surface of the anode 300. [ Similarly, at least a part of the base electrolyte 100 of the electrolyte mixture solution 120 is absorbed by the positive electrode 300 and / or the negative electrode 400 to form the self-assembled carbon film 150 containing the electrolyte The second electrolyte surface 150b contacting the one surface of the separation membrane 400 may be self-assembled to have a shape corresponding to the shape of one surface of the separation membrane 400. [

The surface roughness of the anode 150 may be greater than the surface roughness of the separator 400. Accordingly, the surface roughness of the first electrolyte surface 150a of the self-assembled carbon film 150 containing the electrolyte formed by self-assembling in a shape corresponding to the shape of one surface of the anode 150, The surface roughness of the second electrolyte surface 150b of the self-assembled carbon film 150 containing the electrolyte formed by self-assembly in a shape corresponding to the shape of the first electrolyte surface 150b may be larger than that of the second electrolyte surface 150b.

5, when one surface of the anode 300 contacting the first electrolyte surface 150a of the self-assembled carbon film 150 containing the electrolyte has a convex portion 300V, 1 electrolyte surface 150a may be self-assembled so as to have a recess 150C corresponding to the convex portion 300V of the one surface of the anode 300. [ When the one surface of the anode 300 contacting the first electrolyte surface 150a of the self-assembled carbon film 150 containing the electrolyte has the recess 300C, the first electrolyte surface 150a, May be self-assembled so as to have a convex portion 150V corresponding to the concave portion 300C of the one surface of the anode 300. [

The self-assembled carbon film 150 containing the electrolyte is self-assembled into a shape corresponding to the one surface of the anode 300 and the shape of the one surface of the separator 400, The contact area between the first electrolyte surface 150a and the first electrolyte surface 150b and the contact area between the first electrolyte surface 150b and one surface of the separation membrane 400 may be increased. Accordingly, ion conductivity and electrical conductivity in the lithium sulfur battery according to the present invention can be improved.

Unlike the embodiment of the present invention described above, in order to suppress the elution of sulfur from the anode, when a lithium carbon battery is manufactured by inserting a porous carbon film formed of a substance capable of adsorbing sulfur into the electrolyte A complicated manufacturing process such as filtering, peeling off, and drying using a vacuum pump is required for manufacturing the porous carbon film, so that the process time and process cost are increased, and mass production There is a limit to In addition, since the porous carbon membrane inserted into the electrolyte is structurally incompletely integrated with the anode and the separator, the contact area between the porous carbon membrane and the anode and the separator is narrow, so that the ion conductivity and electrical conductivity in the cell are poor. In addition, the porous carbon film has a limitation in suppressing sulfur (S) eluted from the anode, and the capacity and life characteristics are poor.

However, as described above, according to the embodiment of the present invention, the electrolyte mixture solution 120 including the carbon material 200 is prepared, and the electrolyte mixture solution 120 is mixed with the electrolyte solution A self-assembled carbon film 150 containing the electrolyte containing the carbon material 200 may be formed between the anode 300 and the separator 400. Accordingly, the process time and the process cost of the lithium sulfur battery including the self-assembled carbon film 150 containing the electrolyte can be reduced.

Also, at least a part of the base electrolyte of the electrolyte mixture solution is absorbed into the battery structure, and the self-assembled carbon film containing the electrolyte may be self-assembled into a shape corresponding to the shape of one surface of the anode and one surface of the separator. have. Accordingly, a lithium selenium battery in which the contact area between the anode and the self-assembled carbon film containing the electrolyte and the electrolyte is increased to improve ionic conductivity and electrical conductivity, and a method of manufacturing the same can be provided.

In addition, due to the carbon material contained in the self-assembled carbon film containing the electrolyte, sulfur (S) eluted from the anode can be effectively suppressed, and the electrical conductivity of the battery Can be improved. Accordingly, the capacity and life characteristics of the battery are improved, and a highly reliable lithium-sulfur battery improved in charging and discharging efficiency and a manufacturing method thereof can be provided.

Hereinafter, a characteristic evaluation result of the lithium sulfur battery manufactured according to the above-described embodiment of the present invention will be described.

Preparation of Lithium Sulfate Battery According to Examples

Dimethoxyethane and 1,3-dioxolane were added to a 50 ml vial at a ratio of 1: 1, followed by stirring to prepare a mixed solvent . 1 M LiTFSI (trifluoromethanesulfonyl) imide) and 0.4 M lithium nitrate (LiNO ₃ ) were added to the prepared mixed solvent, followed by stirring at room temperature (25 캜) to prepare a base electrolyte. 0.25 g of multi-walled carbon nanotubes (MWCNT) was added to 5 mL of the base electrolyte and stirred in a glove box of an argon gas environment to prepare an electrolyte mixed solution.

Sulfur, a carbon conductive agent, and fluorinated polyvinylidene (PVDF) in a ratio of 8: 1: 1 to a solvent of N-methyl-2-pyrrolidone A slurry type current collector was produced. The current collector in the form of a slurry was coated on an aluminum foil to a thickness of 100 mu m and dried in a vacuum oven at 50 DEG C for 24 hours to remove the remaining solvent to prepare a positive electrode.

A battery structure was manufactured using the above anode having a sulfur content of 3 mg / cm ² , a porous separator containing polypropylene, and a negative electrode including a lithium foil. The prepared electrolyte solution mixture was injected between the anode and the separator of the cell structure, and then dried to form a self-assembled carbon film containing the electrolyte according to an embodiment of the present invention, that is, a lithium battery having an MWCNT- A sulfur battery was prepared. The battery cycle of the lithium sulfur battery in which the MWCNT-self-assembled carbon film was formed was repeated at a constant current rate of 0.5 C within a voltage range of 1.9 V to 2.8 V.

Preparation of Lithium Sulfate Battery According to Comparative Example

The multiwalled carbon nanotube (MWCNT) is added to a water solvent and subjected to a filtering, peeling off and drying process using a vacuum pump to obtain a carbon material containing no electrolyte That is, a bare MWCNT film.

The bare MWCNT is inserted into the electrolyte in the liquid phase state after the base electrolyte is injected in a liquid state between the anode and the separator manufactured according to the embodiment of the present invention, . The battery cycle of the lithium-sulfur battery including the bare MWCNT film was repeated at a constant current rate of 0.5 C within the voltage range of 1.9 V to 2.8 V, like the lithium-sulfur battery according to the embodiment of the present invention.

6 is SEM images of the surface and side surfaces of the bare MWCNT film and the MWCNT-self-assembled carbon film included in the lithium sulfur battery according to Examples and Comparative Examples of the present invention. 6 (a) is an SEM (Scanning Electron Microscope) image of a surface and a side surface of a bare MWCNT film according to a comparative example of the embodiment of the present invention, and FIG. 6 (b) SEM (Scanning Electron Microscope) images of the surface and side surfaces of the MWCNT self-assembled carbon film.

6, a lithium-sulfur battery according to the above-described Examples and Comparative Examples was subjected to a charge-discharge cycle using an SEM (Scanning Electron Microscope) The detailed images of the surface and side of the MWCNT-self-assembled carbon film and the bare MWCNT film were measured.

6 (a) and 6 (b), it was confirmed that the surface of the anode was completely covered with the MWCNT.

6 (a), cracks were observed on the surface of the bare MWCNT film, and on the side of the bare MWCNT film, the bare MWCNT film was incompletely integrated with the cathode. This bare MWCNT film is different from the MWCNT self-assembled carbon film according to the embodiment of the present invention in that it is a separate component having the original shape in assembling the battery, ) Is low.

On the other hand, as can be seen from FIG. 6 (b), it was confirmed that the surface of the MWCNT self-assembled carbon film according to the embodiment of the present invention had no cracks and had a totally tight surface structure. On the side of the MWCNT-self-assembled carbon film, it was confirmed that the MWCNT-self-assembled carbon film was completely integrated with the anode. This is because the MWCNT-self-assembled carbon film according to the embodiment of the present invention is self-assembled between the anode and the separator, so that the structural flexibility with the anode is high. The tightly integrated structure of the anode and the MWCNT-self-assembled carbon film can effectively suppress sulfur (S) eluted from the anode and efficiently provide an electron transfer path.

7 is FIB-SEM images of the bare MWCNT film and the MWCNT self-assembled carbon film included in the lithium sulfur battery according to the comparative example and the embodiment of the present invention. 7 (a) is an FIB-SEM image of the bare MWCNT film included in the lithium selenium battery according to the comparative example, and FIG. 7 (b) is a FIB-SEM image of the MWCNT- FIB-SEM image of self-assembled carbon film.

7, a charge / discharge cycle of the lithium-sulfur battery according to the above-described Examples and Comparative Examples was carried out using a FIB-SEM (Focused Ion Beam Scanning Electron Microscope) The cross-sectional images of the MWCNT-self-assembled carbon film included in the lithium sulfur battery and the bare MWCNT film in the direction corresponding to one surface of the anode were measured.

As shown in FIG. 7 (a), a large amount of pores and cracks were observed on the cross section of the bare MWCNT film. The bare MWCNT film was judged to have a structure in which sulfur (S) eluted from the anode could not be efficiently suppressed due to the pores and cracks having a large size existing in the cross section of the bare MWCNT film.

On the other hand, as can be seen from FIG. 7 (b), the cross-section of the MWCNT-self-assembled carbon film was relatively tight compared to the bare MWCNT film and confirmed that fine pores existed. The fine pore in the cross section of the MWCNT-self-assembled carbon film can effectively provide an electron transfer path and effectively suppress sulfur (S) eluted from the anode.

FIG. 8 is a TEM (Transmission Electron Microscope) image and electron energy loss spectroscopy (EELS) images of a bare MWCNT film and a MWCNT-self-assembled carbon film included in a lithium sulfur battery according to Examples and Comparative Examples of the present invention. 8 (a) and 8 (c) illustrate TEM (Transmission Electron Microscope) images and electron energy loss spectroscopy (EELS) images of MWCNTs in the MWCNT self-assembled carbon film according to an embodiment of the present invention. to be. 8B and 8D are TEM (Transmission Electron Microscope) images and EELS (electron energy loss spectroscopy) images of the MWCNTs in the bare MWCNT film according to the comparative example of the present invention.

8, a lithium sulfur battery including the MWCNT self-assembled carbon film manufactured according to an embodiment of the present invention, and a lithium sulfur battery including the bare MWCNT membrane manufactured according to the comparative example of the present invention, (1.9 to 2.8 V, 0.5 C) to the MWCNT-self-assembled carbon film and the lithium selenium battery including the bare MWCNT film and the MWCNT-self-assembled carbon film, The bare MWCNT films were separated and TEM (Transmission Electron Microscope) and EELS (electron energy loss spectroscopy) images were measured.

8 (a) and 8 (c), in the case of the MWCNT of the MWCNT self-assembling carbon film manufactured according to the embodiment of the present invention, even though sulfur (S) eluted from the anode was adsorbed Nevertheless, the surface of the MWCNT was found to be smooth.

8 (b) and 8 (d), in the case of the MWCNT of the bare MWCNT film prepared according to the comparative example of the embodiment of the present invention, sulfur (S) It was confirmed that the adsorbed on the surface of MWCNT was rugged.

Thus, the MWCNT self-assembled carbon film manufactured according to the embodiment of the present invention is superior to the bare MWCNT film manufactured according to the comparative example of the present invention, And the characteristics were maintained excellent.

FIG. 9 is a specific capacity graph of a lithium selenium battery including the MWCNT self-assembled carbon film and the bare MWCNT film manufactured according to the embodiment of the present invention and the comparative example according to the voltage according to the current rate. 9 (a) is a graph showing a specific capacity according to a voltage according to a current rate of the bare MWCNT film manufactured according to the comparative example of the embodiment of the present invention, and FIG. 9 (b) Is a specific capacity graph according to the voltage of the MWCNT-self-assembled carbon film manufactured according to the embodiment of the present invention, according to the current rate.

Referring to FIG. 9, for the lithium sulfur battery having the MWCNT self-assembling carbon film formed according to the embodiment of the present invention and the comparative example according to the embodiment of the present invention and the lithium sulfur battery having the bare MWCNT film formed, (0.1C, 0.2C, and 0.5C), 100 cycles were charged and discharged, and specific capacity according to the voltage was measured.

As can be seen from Figures 9 (a) and 9 (b), when the current rate is 0.5 C and 100 cycles are charged / discharged, the current rate is 0.1 C and 0.2 C, It was confirmed that the non-capacitance change value according to the voltage was larger than that in the case where the voltage was applied. The initial specific capacity value of the lithium sulfur battery in which the bare MWCNT film formed at the same voltage and current rate is 0.5 C is 783 mAh g ^-1 and the current rate is 0.5, the voltage of the lithium sulfur battery in which the MWCNT- Was 851 mAh g < ^{-1 &} gt ;. It was confirmed that the initial specific capacity value according to the voltage of the lithium sulfur battery in which the MWCNT-self-assembled carbon film was formed was larger than the initial specific capacity value of the lithium sulfur battery in which the bare MWCNT film was formed Respectively.

Although not shown in FIGS. 9A and 9B, the lithium selenium battery having the MWCNT-self-assembled carbon film formed thereon and the lithium selenium battery having the bare MWCNT film formed therein are subjected to charge and discharge of 100 cycles, The specific capacity was measured by varying the density (0.1 A g ^-1 to 3 A g ^-1 ). Similarly to the case described with reference to FIGS. 9A and 9B, in the case of a relatively low current density of 0.1 A g ^-1 (approximately 0.06 C in terms of current rate) It was confirmed that there was no large difference in the specific capacity value according to the density. On the other hand, in the case of 3A g ^-1 , which is a relatively high current density, it was confirmed that the specific capacity was 2.4 times higher than that in the case of the current density of 0.1 A g ^-1 . This is because, as described with reference to FIG. 6, the structure of the MWCNT-self-assembled carbon film manufactured according to the present invention is not cracks-tight and the MWCNT-self-assembled carbon film is completely integrated with the anode Therefore, it is judged that the electron transfer path is structurally provided in the cell efficiently.

FIG. 10 is a graph of specific capacity according to an increase in the cycle number of the lithium-sulfur battery manufactured according to the embodiment of the present invention and the comparative example.

Referring to FIG. 10, the lithium sulfur battery having the MWCNT-self-assembling carbon film formed according to the embodiment of the present invention and the comparative example according to the embodiment of the present invention and the lithium sulfur battery in which the bare MWCNT film is formed and the MWCNT- For the original carbonaceous membrane and the original lithium-sulfur battery (anode / electrolyte / separator / cathode) in which the bare MWCNT film was not formed, the specific capacity with increasing battery cycle was measured when the current rate was 0.5C.

As can be seen from FIG. 10, it was confirmed that the specific capacity value of the original lithium-sulfur battery was significantly lower than that of the lithium sulfur battery in which the MWCNT-self-assembling carbon film was formed and the bare MWCNT film. From this, it was confirmed that the performance of the battery was poor when the structure for suppressing the sulfur (S) eluted from the anode was not provided.

On the other hand, in the case of the lithium sulfur battery in which the MWCNT self-assembling carbon film was formed and the lithium selenium battery in which the bare MWCNT film was formed according to the examples of the present invention and the comparative examples of the present invention, It was confirmed that the non-capacity value was much higher as the battery cycle number increased. The non-capacity value of the lithium-sulfur battery in which the MWCNT-self-assembled carbon film was formed was found to be 22% larger than that of the lithium-sulfur battery in which the bare MWCNT film was formed.

FIG. 11 is a graph showing a specific capacity value according to an increase in the number of battery cycles when the amount of MWCNT contained in the MWCNT-self-assembled carbon film of the lithium sulfur battery manufactured according to the embodiment of the present invention is different.

Referring to FIG. 11, a lithium sulfur battery having the MWCNT-self-assembled carbon film was prepared according to an embodiment of the present invention. The amount of MWCNT (0 mg, 2 mg, 3 mg, and 4 mg) . For the lithium-sulfur battery in which the MWCNT-self-assembled carbon film was formed with different amounts of MWCNTs contained therein, the non-capacity value with increasing battery cycles was measured when the current rate was 0.5C.

11, when the amount of MWCNT contained in the MWCNT-self-assembled carbon film is 3 mg and 4 mg, the initial specific capacity value is about 900 mAh g ^-1 , and even after 100 cycles of charging / Value of 750 mAh g < ^-1 > or more, and the MWCNT content of the MWCNT-self-assembled carbon film was 1 mg and 2 mg, respectively. Thus, when the MWCNT-self-assembled carbon film is manufactured to contain 3 to 4 mg of carbon material in the production of the MWCNT-self-assembled carbon film according to the present invention, the lithium sulfur It was found that the performance of the battery can be optimized.

11, when the self-assembled carbon film according to the present invention contains 3 to 4 mg of the carbon material at 3 mg of sulfur and thus produces a lithium sulfur battery according to an embodiment of the present invention, the battery performance Can be optimized.

Thus, a lithium-sulfur battery can be manufactured by forming a self-assembled carbon film containing an electrolyte containing a carbon material in a battery structure. The self-assembled carbon film containing the electrolyte can be produced through a simplified process such as stirring and drying, so that process time and process cost can be reduced. Since the self-assembled carbon film containing the electrolyte is formed by self-assembling between the anode and the separator, it has a structure in which the anode and the separator are in intimate contact with each other. Therefore, lithium ions having improved ionic conductivity and electric conductivity A battery may be provided.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention.

100: Base electrolyte
120: electrolyte mixture solution
150: self-assembled carbon film containing electrolyte
150a: first electrolyte side
150b: the second electrolyte side
150c and 300c:
150v, 300v: convex portion
200: carbon material
205: Carbon nanotubes
400: cathode
500: membrane
600: battery structure

Claims (14)

Preparing a base electrolyte;
Preparing an electrolyte mixture by mechanically mixing the base electrolyte and the carbon material; And
And injecting the electrolyte mixture solution into a battery structure,
After the electrolyte mixture solution is injected into the cell structure,
At least a portion of the base electrolyte in the electrolyte mixture solution is absorbed into the cell structure to form a self-assembly carbon layer containing the remaining carbon material and the electrolyte including the base electrolyte Gt; < tb >< / TABLE >
delete The method according to claim 1,
The mechanical mixing of the base electrolyte and the carbon material,
And stirring the base electrolyte and the carbon material.
The method according to claim 1,
Wherein the carbon material comprises at least one kind of carbon allotrope.
The method according to claim 1,
Wherein the battery structure comprises a cathode, a separator, and an anode which are sequentially stacked.
6. The method of claim 5,
The step of injecting the electrolyte mixed solution into the cell structure comprises:
Wherein the electrolyte mixture solution is injected between the anode and the separator.
6. The method of claim 5,
Wherein the self-assembled carbon film containing the electrolyte is formed by self-assembling a surface of the anode in contact with the self-assembled carbon film containing the electrolyte and a shape corresponding to the shape of one surface of the separator, Gt;
A cathode comprising carbon (C) and sulfur (S);
A self-assembly carbon layer disposed on the anode, the self-assembly carbon layer having a shape corresponding to the shape of one surface of the anode and containing an electrolyte;
A separator on the self-assembled carbon film containing the electrolyte; And
And an anode including lithium (Li) on the separator,
Wherein the self-assembled carbon film containing the electrolyte has a first electolyte surface in contact with one surface of the anode and corresponding to the shape of the one surface of the anode, and a second electolyte surface in contact with one surface of the separator, And a second electrolyte surface corresponding to the shape of the one surface,
When the one surface of the anode has a convex portion, the first electrolyte surface has a concave portion corresponding to the convex portion of the one surface of the anode,
Wherein the first electrolyte surface has a convex portion corresponding to a concave portion of the one surface of the anode when the one surface of the anode has a concave portion.
9. The method of claim 8,
The self-assembled carbon film containing the electrolyte includes at least one carbon allotrope.
9. The method of claim 8,
Wherein the self-assembled carbon film containing the electrolyte comprises 3 to 4 mg of the carbon.
delete delete 9. The method of claim 8,
Wherein the surface roughness of the first electrolyte surface of the self-assembled carbon film containing the electrolyte is larger than the surface roughness of the second electrolyte surface of the self-assembled carbon film containing the electrolyte.
9. The method of claim 8,
Wherein the initial shape of the first electrolyte surface and the second electrolyte surface of the self-assembled carbon film containing the electrolyte is kept constant even when the cycle of the lithium sulfur battery is increased.

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