KR20140135422A - Positive electrode using anodic aluminum oxide template for Lithium Sulfur secondary battery and method for preparing the same - Google Patents

Abstract

The present invention relates to a method for preparing a positive electrode for a lithium sulfur secondary battery comprising: a) a step of providing an aluminum oxide template having a pore, wherein an end of the pore is closed; b) a step of coating the surface inside the pore of the aluminum oxide template as carbon; c) a step of filling sulfur into the carbon-coated pore of the aluminum oxide template of the step b); d) a step of attaching a sulfur-filled pore surface of the sulfur-filled aluminum oxide template to a current collector; e) a step of removing aluminum oxide in the aluminum oxide template attached to the current collector, and to a positive electrode for a lithium sulfur secondary battery prepared by the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode for a lithium-sulfur secondary battery using an aluminum oxide template, and a method for manufacturing the positive electrode.

The present invention relates to a positive electrode for a lithium-sulfur secondary battery using an aluminum oxide template and a method for manufacturing the same, and more particularly, to a method for preparing a carbon nanotube by using an aluminum oxide template as a positive electrode for a lithium- To a cathode for a lithium-sulfur secondary battery having a structure capable of rapidly charging and discharging and minimizing the influence of volume change caused by dissolution of polysulfide and charging / discharging, and a method for manufacturing the same.

BACKGROUND ART [0002] Research on a large-capacity secondary battery capable of replacing a lithium secondary battery currently in use due to the development of the IT industry and the demand for development of electric vehicles is underway. Lithium secondary batteries are difficult to exhibit high energy density due to their low cathode material capacity compared to cathodes and are difficult to be used in automobiles and the like.

Hwang has a theoretical capacity about 5 times (1675 mAh / g) higher than the cathode material of existing lithium secondary battery. In addition, Hwang has environment-friendly, abundant reserves, and cheap prices.

As a prior art related to the production of the above lithium sulfur secondary battery, in Patent Document 10-2005-0038254 (Apr. 27, 2005), a sulfur cathode active material, a binder, a conductive agent, and an electrically conductive linear Discloses a lithium sulfur secondary battery comprising a positive electrode containing a fiber.

However, the capacity of the lithium sulfur secondary battery including the conventional technology is lower than the theoretical value, and improvement is required. This is due to the low electrical conductivity of sulfur itself and the dissolution of polysulfides into electrolytes produced during the electrochemical reaction.

In order to solve the low electrical conductivity of sulfur in the lithium sulfur secondary battery, research has been conducted to improve the characteristics of the battery by increasing the conductivity of the electrode material using a carbonaceous material. Mater. 2009, 8, 500-506, a study using porous mesoporous carbon has been proposed, and another example is Chem. Commun., 2012, 48, 1233-1235 suggests the use of graphene to obtain improved battery characteristics.

The polysulfide (LiSx, x = 3 to 8) formed during the charging and discharging of the lithium sulfur secondary battery is an intermediate product of S8 generated during full charge and Li ₂ S generated during complete discharge, and is dissolved in the electrolyte solution. The polysulfide dissolved in the electrolyte reacts with the lithium in the negative electrode and moves to the positive electrode to form Li ₂ S that is not dissolved in the electrolyte. This results in low electric conductivity and blocking of the lithium surface to interfere with the electrochemical reaction. Dissolution of the polysulfide causes a continuous decrease of the cathode material, and as the battery continues to be charged and discharged, it causes a constant capacity decrease.

Therefore, by including a carbon film which can prevent direct contact with an electrolyte even when polysulfide is formed while minimizing the formation of polysulfide, lithium having a structure capable of fast charging / discharging and minimizing the influence of volume change upon charging / discharging There is a continuing need for the manufacture of electrodes for sulfur secondary batteries, and additional research and development is needed to solve these problems.

Published Japanese Patent Application No. 10-2005-0038254 (Apr. 27, 2005)

Nat. Mater. 2009, 8, 500-506 Chem. Commun., 2012, 48, 1233-1235

Accordingly, the present invention relates to a method for producing sulfur nanowires (nanorods) comprising a carbon film capable of preventing direct contact with an electrolyte even when polysulfide is formed while minimizing the formation of polysulfide by using a monoclinic sulfur, To provide an electrode material for a lithium sulfur secondary battery having a structure capable of rapidly charging and discharging and minimizing the influence of a change in volume caused by charging and discharging.

Another object of the present invention is to provide a positive electrode for a lithium sulfur secondary battery including the electrode material for the lithium sulfur secondary battery and a lithium sulfur secondary battery including the positive electrode.

Another object of the present invention is to provide a novel process for producing a positive electrode for a lithium-sulfur secondary battery using an aluminum oxide template.

Accordingly, the present invention provides a method of manufacturing an aluminum oxide template, comprising: a) providing an aluminum oxide template having pores and having one end of the pores closed; b) coating the interior of the aluminum oxide template pores with carbon; c) filling the carbon coated pores of the aluminum oxide template of step b) with sulfur; d) attaching the sulfur-filled pore surface of the sulfur-filled aluminum oxide template to the current collector; And e) removing aluminum oxide of the aluminum oxide template adhered to the current collector. The present invention also provides a method of manufacturing a positive electrode for a lithium sulfur secondary battery.

The present invention also provides a positive electrode for a lithium sulfur secondary battery, which is produced by the manufacturing method comprising the steps a) to e).

The present invention also provides a method of manufacturing a semiconductor device comprising a current collector including a metal component, a plurality of pillar-shaped pillars on the current collector, each of the pillars including a plurality of sulfur nanowires having a shape of pores formed in an aluminum oxide template, And a carbon coating layer formed on the surfaces of the nanowires.

The present invention also provides a positive electrode for a lithium sulfur secondary battery formed on a current collector and including a plurality of sulfur nanowires coated with carbon.

The present invention also provides a lithium sulfur secondary battery comprising a positive electrode, a negative electrode and an electrolyte, and a positive electrode for a lithium sulfur secondary battery produced by the manufacturing method including the steps a) to e).

According to the present invention, by using sulfur nanowires including a carbon film that can prevent direct contact with an electrolyte even when polysulfide is formed while minimizing formation of polysulfide by using monoclinic sulfur, And an electrode material for a lithium sulfur secondary battery having a structure that minimizes the influence of a change in volume caused by charging and discharging, and a lithium sulfur secondary battery including the electrode material.

Further, the positive electrode for a lithium-sulfur secondary battery obtained by the present invention can adhere the electrode material produced by the present invention directly to the current collector without using a binder, thereby reducing the electrical conductivity by the binder and reducing the capacity accordingly And can move electrons smoothly through a well-aligned one-dimensional structure to exhibit high efficiency at a high charge / discharge rate.

Further, the positive electrode for a lithium-sulfur secondary battery of the present invention has a contact area with an electrolytic solution widened by a high surface area of a positive electrode material, and facilitates the movement of electrons and lithium to the active material, thereby exhibiting a high capacity electrochemical characteristic.

The carbon layer coated on the sulfur nano-wire may exhibit high battery characteristics by increasing the electrical conductivity of the active material. The carbon layer may prevent direct contact between the sulfur and the electrolytic solution and prevent polysulfide ) Is prevented from being eluted into the electrolytic solution, it is possible to reduce the battery capacity decrease due to an increase in the number of charge / discharge cycles.

1 is a flowchart showing a method of manufacturing a positive electrode for a lithium sulfur secondary battery according to the present invention.
FIG. 2 is a diagram illustrating a method of manufacturing a positive electrode for a lithium sulfur secondary battery according to an embodiment of the present invention.
3 is a SEM image of a carbon coated sulfur nanowire fabricated according to an embodiment of the present invention.
FIG. 4 is a TEM image of a carbon-coated sulfur nanowire fabricated according to an embodiment of the present invention.
FIG. 5 is a view showing an EDS mapping image of a carbon-coated sulfur nanowire fabricated according to an embodiment of the present invention.
FIG. 6 is a graph showing the charging / discharging capacity evaluation value of the positive electrode for a lithium sulfur secondary battery manufactured by the present invention.
7 is a graph showing lifetime characteristics of a positive electrode for a lithium sulfur secondary battery manufactured by the present invention.
8 is a graph showing an electrochemical graph (galvanostatic curve) of a lithium-sulfur battery including a cathode manufactured by the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings of the present invention, the sizes and dimensions of the structures are enlarged or reduced from the actual size in order to clarify the present invention, and the known structures are omitted so as to reveal the characteristic features, and the present invention is not limited to the drawings . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

The present invention relates to a positive electrode for a lithium sulfur secondary battery, a method for producing the same, and a lithium sulfur secondary battery including the positive active material. The lithium sulfur secondary battery of the present invention includes a collector Lt; RTI ID = 0.0 > of < / RTI >

Generally, the lithium sulfur secondary battery may include a negative electrode, an electrolyte, and a positive electrode.

The negative electrode includes a negative electrode active material selected from the group consisting of a material capable of reversibly intercalating or deintercalating lithium ions, a material capable of reversibly forming a compound with lithium, a lithium metal, and a lithium alloy And the electrolyte may include a lithium salt and an organic solvent.

The lithium-sulfur secondary battery of the present invention can be produced by a method of the steps shown in FIGS. 1 and 2, and more specifically, a method of manufacturing a lithium-sulfur secondary battery comprising the steps of: a) Providing a template; b) coating the interior of the aluminum oxide template pores with carbon; c) filling the carbon coated pores of the aluminum oxide template of step b) with sulfur; d) attaching the sulfur-filled pore surface of the sulfur-filled aluminum oxide template to the current collector; And e) removing aluminum oxide in the aluminum oxide template adhered to the current collector.

FIG. 1 illustrates a method of manufacturing a positive electrode for a lithium sulfur secondary battery according to the present invention. FIG. 2 illustrates a method of manufacturing a positive electrode for a lithium sulfur secondary battery according to an embodiment of the present invention. In FIG. 2, an aluminum oxide template obtained according to each of the steps a) to e) described above and a finally obtained carbon-coated sulfur nanowire-adhered current collector are shown.

The method for manufacturing the positive electrode for a lithium sulfur secondary battery of the present invention will be described in detail below.

The method for manufacturing the positive electrode for a lithium sulfur secondary battery includes, as a first step, a step of providing an aluminum oxide template having pores and having one end of the pores closed.

The aluminum oxide template is commercially available or may be provided by forming an aluminum oxide layer by anodizing aluminum with a metal layer. Here, anodization refers to a process of electrolysis in an electrolyte solution using a metal layer as a cathode. When the anodic oxidation process is carried out, the constituent material of the metal layer dissolves into the electrolyte, the thickness of the natural oxide film formed on the metal layer can be increased, and an aluminum oxide film having a structure including straight and uniform cylindrical pores can be formed .

This can be easily understood through the structure of FIG. 2A shows an anodized aluminum oxide template provided in the present invention. As shown in FIG. 2A, the aluminum oxide template provided in the present invention has uniformly and regularly arranged pores, and serves as a template (template) of sulfur nanowires through subsequent processes.

In the present invention, the aluminum oxide template is prepared by using, for example, bulk aluminum. In order to make an aluminum oxide (AAO) template having high degree of alignment with regularly arranged pores, firstly, the aluminum surface can be made flat by electrolytic polishing have. Subsequently, primary anodization can be carried out using an acid solution (for example, oxalic acid). Thereafter, the formed aluminum oxide is wet-etched with an acid solution such as a mixed solution of chromic acid and phosphoric acid, and secondary anodization is performed under the same conditions to form an aluminum oxide nanotemplate in which pores are regularly arranged.

The pore size of the aluminum oxide (AAO) template and the degree of alignment of the template can be easily controlled by adjusting the reaction conditions in the process of manufacturing the aluminum oxide (AAO) template. In the present invention, The size and alignment of the finally obtained sulfur nanowires can be controlled by adjusting the degree of alignment of the nanowires.

The aluminum oxide template used in the present invention may preferably have a pore size of 15 to 400 nm and a thickness of 10 to 300 um.

The second step of the manufacturing method of the present invention is a step of coating the inside surface of the aluminum oxide template pores with carbon. The carbon coating can be coated with a predetermined thickness inside the aluminum oxide template pores, and various coating methods not limited to the type of the coating method can be used.

For example, the carbon coating can be made by chemical vapor deposition (CVD). This is achieved by flowing a carbon source as a reaction source together with a carrier gas into the reactor and depositing the carbon source in the surface of the pores by a chemical reaction within a range of suitable temperatures (about 400 ° C to about 1000 ° C) Lt; / RTI >

Here, a carrier gas for transferring the reaction source can be used. As the carrier gas, argon or nitrogen gas may be used.

Preferably, the carbon coating may be formed by a CVD method using a hydrocarbon as a carbon source, and more preferably by depositing ethylene gas or acetylene gas as the hydrocarbon at 550 to 800 degrees for 10 minutes to 6 hours .

FIG. 2B shows an anodized aluminum template carbon-coated on an aluminum oxide template using the CVD method.

The third step of the process of the present invention is to fill the carbon coated pores of the aluminum oxide template with sulfur.

This is a step of filling the pores with molten sulfur so that carbon-coated sulfur nanowires can be obtained when the aluminum oxide is removed in a subsequent process, so that sulfur can be filled in a vacuum or reduced-pressure atmosphere.

In addition, the sulfur may be put into the pores to fill the pores with the sulfur, but it is preferable that the sulfur in the form of solid powder is put together with the aluminum oxide template in a vacuum chamber or the like, and the sulfur is melted at a suitable temperature So that the sulfur can penetrate into the pores in the aluminum oxide template to fill the pores.

FIG. 2C illustrates that the lower pores of the carbon-coated aluminum oxide template are filled with sulfur.

The present invention may further include a step of removing residual sulfur on the surface of the template as a process after filling with sulfur.

The fourth step of the manufacturing method of the present invention is a step of adhering the sulfur-filled pore surface of the sulfur-filled aluminum oxide template to the current collector.

This is a step of electrically connecting the current collector and the carbon-coated sulfur nanowire by bonding the surface of the aluminum oxide template having pores filled with sulfur to the current collector.

In order to electrically connect the current collector and the carbon-coated sulfur nanowire, in the present invention, a conductive paste or a material including a conductive polymer is applied to the sulfur-filled pore surface of the aluminum oxide template to form the sulfur- It can be bonded to the whole of the collector.

More preferably, an Ag paste containing an epoxy component may be applied and adhered to the pore surface of the aluminum oxide template filled with sulfur and / or the current collector for the above bonding.

2 (d) shows that the collector is attached to the pore surface of the aluminum oxide template filled with sulfur.

In the present invention, the current collector is not particularly limited, but it is preferable to use a conductive material such as stainless steel, aluminum, copper, or titanium. A carbon-coated aluminum current collector can also be used for adhesion to the active material and low contact resistance.

Further, a platinum layer can be introduced by sputtering platinum before the aluminum oxide template is adhered to the current collector, and a heat treatment process can be further introduced after sputtering the platinum layer.

In general, a positive electrode used in a lithium sulfur secondary battery includes a positive electrode active material, a conductive agent, and a binder. The active material is composed of an elemental sulfur (S8) solid Li2Sn (n≥1), Li2Sn 1) the dissolved kaessol light, organic sulfur compounds, and carbon-sulfur polymer _{[(C 2 Sx) n,} x = 2.5 to 50, n ≥ 2] and one or more of the sulfur-based material selected from the group used consisting of the As a conductive agent for allowing electrons to move smoothly in the cathode active material together with the cathode active material, a conductive material or a conductive polymer such as a graphite-based material, a carbon-based material, or the like may be preferably used, and a role of attaching the cathode active material to the current collector (Vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alkylated polyethylene oxide, crosslinked polyethylene oxide, A copolymer of polyvinylidene fluoride, polyhexafluoropropylene and polyvinylidene fluoride (trade name: Kynar), poly (ethyl acrylate), polytetrafluoroethylene (polyvinylidene fluoride) , Polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, polystyrene, derivatives thereof, blends, copolymers and the like can be used. In the present invention, carbon-coated sulfur nanowires are used as the cathode active material, and further binder Binder) is not used.

As a final step of the manufacturing method of the present invention, the step of removing aluminum in the aluminum oxide template adhered to the current collector may include completely removing the aluminum oxide by treating the aluminum oxide template bonded to the current collector with an acid or basic aqueous solution .

For example, the aluminum oxide is treated with a basic aqueous solution of sodium hydroxide or potassium hydroxide (0.5 M to 8 M concentration) for 10 minutes to 5 days to remove all aluminum oxide components, so that only carbon-coated sulfur nano- In the attached form, the anode of the present invention can be formed.

In FIG. 2E, all the aluminum oxide of the aluminum oxide template is removed, and a plurality of carbon-coated sulfur nanowires are attached to the current collector to form the anode for a lithium sulfur secondary battery of the present invention.

The present invention also provides a positive electrode for a lithium sulfur secondary battery formed on a current collector and including a plurality of carbon nanotubes coated with sulfur.

The positive electrode for a lithium sulfur secondary battery formed on the current collector and including a plurality of sulfur coated nanowires coated with carbon may be obtained by the manufacturing method comprising steps a) to e) provided in the present invention.

The present invention also provides a method of manufacturing a semiconductor device, comprising: a current collector including a metallic component including a metal component; a plurality of pillar-shaped pillar-shaped pillar- And a carbon coating layer formed on the surface of the plurality of sulfur nanowires.

In one embodiment, the thickness of the carbon coating layer surrounding the sulfur in the anode may be 0.5 to 10 nm. If the thickness of the coating layer is too thick, the amount of sulfur used as the electrode is reduced. If the thickness of the coating layer is thinner than 3 nm, sulfur contained in the sulfur nanowire may leak out to the external electrolyte, The formed polysulfide can be dissolved in the electrolyte, and the above range is preferable.

The present invention also provides a lithium sulfur secondary battery comprising a cathode, an anode and an electrolyte, wherein the lithium sulfur secondary battery includes the anode obtained by the above-described production method of the present invention.

The electrolyte that can be used in the lithium sulfur secondary battery according to the present invention includes a lithium salt as a supporting electrolyte and includes a non-aqueous organic solvent. The organic solvent of the electrolyte used is that used to properly elemental sulfur (S8), lithium sulfide (Li ₂ S), lithium polysulfide _{(Li 2 Sn, n = 2} , 4, 6, 8 ...) soluble . Examples of the organic solvent include benzene, fluorobenzene, toluene, trifluoro toluene, xylene, cyclohexane, tetrahydrofuran, 2-methyltetrahydrofuran, cyclodextrin, ethanol, isopropyl alcohol, dimethyl carbonate, ethyl Methyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl propionate, ethyl propionate, methyl acetate, ethyl acetate, propyl acetate, dimethoxyethane, 1,3-dioxolane, diglyme, tetraglyme, ethylene carbonate , Propylene carbonate,? -Butyrolactone, and sulfolane.

Examples of the lithium salt as the electrolytic salt include lithium trifluoromethanesulfonimide, lithium triflate, lithium perchlorate, lithium hexafluoroethane (LiAsF ₆ ), lithium triflate Romero burnt sulfonate _{(CF 3 SO 3 Li),} LiPF 6, LiBF 4 or a tetraalkylammonium, e.g., tetrabutylammonium tetrafluoroborate, or liquid state salts at room temperature, for example 1-ethyl-3-methyl Imidazolium salts such as imidazolium bis (perfluoroethylsulfonyl) imide, and the like can be used. The electrolyte comprises a lithium salt at a concentration of 0.5 to 2.0 M.

The electrolyte may be used as a liquid electrolyte or as a solid electrolyte separator. When used as a liquid electrolyte, the separator further includes a separator made of porous glass, plastic, ceramic, or polymer as a physical separator having a function of physically separating the electrode.

The electrolyte separator functions to physically separate the electrodes and to serve as a moving medium for moving metal ions, and electrochemically stable electrical and ionic conductive materials can be used. Examples of such electric and ion conductive materials include glass electrolytes, polymer electrolytes, and ceramic electrolytes. Particularly preferred solid electrolytes are those in which the supported electrolyte salt is mixed with a polymer electrolyte such as polyether, polyimine, polythioether or the like. The solid electrolyte separator may comprise less than about 20% by weight of a non-aqueous organic solvent, in which case it may further comprise a suitable gelling agent to reduce the fluidity of the organic solvent.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for illustrating the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

Example  1: Preparation of Lithium Sulfide Secondary Battery Electrode

1) Manufacture of aluminum oxide template

Two stages of anodic oxidation were performed to prepare the aluminum oxide template.

The aluminum foil with a purity of 99.999% was heat-treated at 400 ° C for 3 hours in a nitrogen atmosphere, electropolished using ethanol: perchloric acid (= 4: 1) as an electrolyte at 20 V for 2 minutes, It makes it flat.

After that, oxalic acid 0.3 M was anodized at 40 V for 5 hours and then a solution of 0.4 M phosphoric acid (H ₃ PO ₄ ) and 0.2 M chromic acid (H ₂ CrO ₄ ) was used And then etched at 60 degrees for 2 hours to remove the aluminum oxide produced in the previous step.

After that, oxalic acid 0.3 M was electrolyzed at 40 V for 1 hour and anodized to produce aluminum oxide. Afterwards, add a template made of 6 wt.% Phosphoric acid for 30 min to widen the pores.

2) Steps to fill the carbon coating and pores with sulfur

The aluminum oxide template made in the tube-shaped furnace was placed and heat treated in a nitrogen atmosphere to 640 ° C. Then, acetylene gas was used as a carbon source and nitrogen gas: acetylene (= 9: 1 v / v) Lt; 0 > C for 2 hours.

The obtained carbon-coated aluminum oxide template is cooled to room temperature by lowering the temperature in a nitrogen atmosphere.

As a subsequent step, the carbon-coated aluminum oxide template and 1 g of sulfur are put together in a vacuum oven and heated to 155 degrees.

As the temperature rises, the sulfur is thawed and held under vacuum (> 10 ^-2 mbar) for 24 hours to allow the molten sulfur to fill the pores.

After 24 hours, the sulfur is removed from the template filled in the pores to remove sulfur on the surface

3) Adhesion of collector and template removal process

Aluminum was used as the current collector, and a platinum layer having a thickness of 15-20 nm was formed by sputtering 250 parts of platinum with a sputterer, followed by heat treatment at 400 degrees for 2 hours under an Ar atmosphere. Thereafter, an Ag epoxy paste as a conductive paste was adhered to the surface of the current collector coated with platinum, and then the side including the sulfur-filled pores of the template was attached.

The Ag epoxy paste may be mixed with a curing agent. If the curing agent is mixed with the curing agent, the curing agent may be cured at 80 ° C for 12 hours.

The aluminum portion of the anodized aluminum template was then removed using a 5 wt% Hg2Cl2 solution.

Finally, the carbon-coated aluminum oxide template to which the current collector is adhered is immersed in a 3M NaOH aqueous solution for 24 hours to etch the aluminum oxide. The obtained positive electrode was immersed in distilled water, washed, and dried to prepare a positive electrode for a lithium sulfur secondary battery of the present invention. The thickness of the carbon coating layer of the thus-formed sulfur nanowire was about 2 nm, and the diameter of the sulfur nanorod was 70 nm.

FIG. 3 is a SEM image of a top surface of a carbon coated sulfur nanowire fabricated according to the above manufacturing method. FIG. 3A) shows a high magnification SEM, and FIG. 3B) shows a low magnification SEM image.

3 a) and 3 b), it is shown that the carbon-coated sulfur nanowires of the present invention are arranged in a regular and uniform manner.

FIG. 4 is a TEM image of carbon-coated sulfur nanowires prepared according to the above-described method. 4A) shows the middle portion of the nanowire at low magnification, and FIG. 4B) shows the image of the end with high magnification.

4 d) and 4 e), it can be seen that a 3 nm carbon layer uniformly surrounds the surface of the sulfur nanowire.

Sulfur was present in the form of monoclinic sulfur in the region of contact with carbon. Sulfur was present in the center of sulfur nanowire in orthorhombic sulfur form.

FIG. 5 is a view showing an EDS mapping image of a carbon-coated sulfur nanowire fabricated according to the above manufacturing method. From the lower right image of FIG. 5, the sulfur nanowires included in the anode of the present invention are filled with sulfur and the surface is coated with carbon.

Example  2: Manufacture of lithium-sulfur secondary battery cell

The fabrication of the cell fabricated according to the present invention is as follows.

The anode and the parts necessary for cell fabrication are placed in a vacuum-treated glove box. The anode is first placed on the cell case. At this time, the anode is a portion including a current collector including carbon-coated sulfur nanowires obtained by the above-described manufacturing method of the present invention.

Three drops of the electrolytic solution in which 1 M of LiPF 6 is dissolved in a 1: 1 volume ratio mixture of EC (ethylene carbonate) and DMC (dimethyl carbonate) is dropped on the anode. After that, the poly-propylene film separator for battery is formed, and the electrolytic solution is dropped by 3 drops.

Finally, a plastic ring is added as a gasket for lifting the Li metal to the cathode and sealing the cell on the edge of the separator and the Li cathode. Place the stainless steel spacer and spring on the cell cover, and press the cover.

Test Example  : Characteristic evaluation of battery

As a method of evaluating the battery manufactured in the present invention, a constant current of 1.0 to 3.0 V vs. Cells were tested in the Li / Li ⁺ potential range to obtain charge / discharge diagrams for each C rate.

FIG. 6 is a graph showing the charging / discharging capacity evaluation value of the positive electrode for a lithium sulfur secondary battery manufactured by the present invention.

As shown in FIG. 6, the anode including carbon-coated sulfur nanowires according to the present invention shows excellent results even at 40 C rate, which is a high discharge rate.

7 is a graph showing lifetime characteristics of a cathode for a lithium sulfur secondary battery manufactured by the present invention. 7a) is the result of measuring 0.5C and 20C after discharging at 0.5C. 150 cycles for 0.5C discharge and 300 cycles for 20C discharge were measured. In case of 7 b), 5 C discharge was performed at 2 C charge and 1000 cycles were measured.

 8 shows an electrochemical graph (galvanostatic curve) of a lithium sulfur battery including a positive electrode manufactured by the present invention

The electrochemical graph of a conventional reported general Li-S battery has two plateau portions during charging and discharging, whereas the present invention has two plateau portions when charged and one And has a flat portion. This is due to the presence of sulfur in the form of monoclinic sulfur rather than stable orthorhombic sulfur at room temperature as shown in TEM analysis results.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (15)

a) providing an aluminum oxide template having pores and having one end of the pores closed;
b) coating the interior of the aluminum oxide template pores with carbon;
c) filling the carbon coated pores of the aluminum oxide template of step b) with sulfur;
d) attaching the sulfur-filled pore surface of the sulfur-filled aluminum oxide template to the current collector; And
and e) removing aluminum oxide of the aluminum oxide template adhered to the current collector. The method according to claim 1,
Wherein the aluminum oxide template of step a) has a pore size of 15 to 400 nm and a thickness of 10 to 300 μm. The method according to claim 1,
The method for producing a positive electrode for a lithium sulfur secondary battery according to claim 1, wherein the carbon coating in step b) is carried out by a CVD method using a hydrocarbon as a carbon source The method of claim 3,
Wherein the carbon coating is formed by depositing ethylene gas or acetylene gas as a carbon source at 550 to 800 DEG C for 10 minutes to 6 hours to form a positive electrode for a lithium sulfur secondary battery The method according to claim 1,
Wherein the step of filling the sulfur in the step c) is performed by melting the sulfur and then filling the molten sulfur in the aluminum oxide template pores with a vacuum or a reduced pressure atmosphere to produce a positive electrode for a lithium sulfur secondary battery The method according to claim 1,
Wherein the step d) comprises applying a conductive paste or a material containing a conductive polymer to the pore surface of the aluminum oxide template filled with sulfur and bonding the pore surface filled with the sulfur to the current collector. ≪ / RTI & The method according to claim 6,
And bonding the pore surface filled with the sulfur to the current collector is performed by applying an Ag paste containing an epoxy component to the pore surface filled with sulfur of the current collector or the aluminum oxide template and bonding the same. Way The method according to claim 1,
Wherein the step (e) comprises a step of removing the aluminum oxide by treating the aluminum oxide template bonded to the collector with an acidic or basic aqueous solution, thereby producing a positive electrode for a lithium sulfur secondary battery 9. The method of claim 8,
Wherein the aluminum oxide is removed by treating in an aqueous solution of sodium hydroxide or potassium hydroxide for 10 minutes to 5 days. A positive electrode for a lithium sulfur secondary battery produced by a manufacturing method according to any one of claims 1 to 9 11. The method of claim 10,
Characterized in that the thickness of the carbon coating surrounding the sulfur in the anode is 0.5 to 10 nm, A lithium sulfur secondary battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the lithium sulfur secondary battery comprises the positive electrode according to claim 10 A current collector containing a metal component;
A plurality of sulfur nanowires formed on the current collector in a plurality of columnar shapes, each column having a shape of pores formed in an aluminum oxide template; And
And a carbon coating layer formed on the surface of the plurality of sulfur nanowires. An anode for a lithium sulfur secondary battery formed on a current collector and including a plurality of sulfur nanowires coated with carbon The method according to claim 13 or 14,
Characterized in that the thickness of the carbon coating layer surrounding the sulfur in the anode is 0.5 to 10 nm. The anode for a lithium sulfur secondary battery

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