KR101904360B1 - Sulfur embedded composite using nonconductor and Li―S battery - Google Patents

Abstract

More particularly, the present invention relates to a positive electrode active material for a lithium-sulfur battery including a composite in which a sulfur element or a sulfur-containing compound is supported on an insulator material, and more particularly to a lithium- (A) mixing a sulfur element or sulfur compound and an insulator material in a weight ratio of 4: 1 to 6: 1 and heating at a temperature of 150 to 160 ° C for 10 to 14 hours; And (b) heating the mixture heated in the step (a) again at 240 to 260 ° C under nitrogen for 2 to 4 hours and cooling the cathode active material for a lithium-sulfur battery.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sulfur-supported composite using a non-conductive material and a lithium-

The present invention relates to a sulfur-supported complex using an insulator and a lithium-sulfur battery including the same.

One of the key technologies contributing to various electronic products is the rechargeable secondary battery technology. Among these secondary batteries, the secondary batteries which are most commonly used today are lithium ion secondary batteries, but the lithium ion secondary batteries have a capacity limit.

On the other hand, the lithium-sulfur battery has a theoretical energy density of 2800 Wh / kg (1675 mAh / g), which is much higher than that of a currently used lithium secondary battery. Also, the sulfur material used as a cathode active material is rich in resources, Has attracted attention as a friendly substance. However, the lithium metal used as the cathode in the lithium-sulfur secondary battery is a lithium metal which dissociates from the lithium metal during the charging / discharging process of the battery and re- And this is a factor that deteriorates the stability of the battery. Therefore, it is pointed out as a main limitation to the commercialization of the lithium-sulfur secondary battery. The lithium polysulfide material, which is an intermediate product generated during the electrochemical reaction, has a high solubility in the organic electrolyte solution and is continuously dissolved during the discharging process. This causes a problem of the lifetime degradation due to the loss of sulfur as the cathode material.

In lithium-sulfur batteries, sulfur has an insulator property, and electrons must be supplied smoothly to sulfur by forming a composite of carbon and a conductive material. In this case, as a carrier capable of supporting sulfur, a carbon material, I am using it. By using porous carbon, carbon nanofibers, carbon nanotubes, graphene or graphene derivatives as the carbon structure, long cycle life and improved capacity retention rate could be realized.

However, when a carbon structure is used, complex processes such as template synthesis, impregnation of a carbon precursor, thermal decomposition at a high temperature, and removal of a template must be accompanied by complicated processes, and a large amount of carbon materials having a nanostructure is difficult to handle It is expensive and causes environmental problems. Also, when a carbon material is used as a sulfur bearing material, the sublimation temperature of sulfur is too low to use an ampoule. Even if an ampoule is used, the degree of adsorption to carbon is very low. (loading density) can be obtained, which causes a lot of cost in the process step.

Therefore, a gradual decrease in capacity over a long period of charge / discharge can not be solved even with a carbon structure, and the capacity decrease due to low binding energy between sulfur and carbon is again a big problem.

As a method for manufacturing a lithium-sulfur battery having improved performance, it is necessary to excavate a new sulfur-supported material capable of substituting for carbon, inhibiting sulfur sublimation as a cathode material, and storing sulfur organic materials.

Korean Patent Publication No. 10-2014-0108609

The present inventors have found that when an insulator material is used as a positive electrode active material for a lithium-sulfur battery, a lithium-sulfur electrochemical conversion reaction can be positively performed by an active sulfur material isolated in an insulator material, Stabilizing properties and excellent cyclicity and speed characteristics when compared with existing sulfur electrodes and confirming that it has a suppressing ability for sulfur sublimation so that the conductive carbon material used in the conventional lithium-sulfur battery manufacturing is sufficiently substituted for the non-conductive material of the present invention And completed the present invention.

Therefore, an object of the present invention is to provide a cathode active material for a lithium-sulfur battery including a composite in which a sulfur element or a sulfur compound is supported on an non-conductive material.

 Another object of the present invention is to provide a method for producing the cathode active material for a lithium-sulfur battery according to the present invention.

Another object of the present invention is to provide a positive electrode active material for a lithium-sulfur battery produced by the method of the present invention; bookbinder; And a cathode comprising the conductive material.

Another object of the present invention is to provide a positive electrode of the present invention, A cathode arranged at a predetermined interval; A separation membrane disposed between the anode and the cathode; And an electrolyte filled between the anode and the cathode.

In order to accomplish the above object, the present invention provides a cathode active material for a lithium-sulfur battery, comprising a composite in which a sulfur element or a sulfur compound is supported on an insulator material.

In one embodiment of the present invention, the sulfur compound may be Li ₂ Sn (n? 1) or an organic sulfur compound.

In one embodiment of the present invention, the non-conductive material may be at least one selected from the group consisting of silica, alumina, titanium oxide, iron oxide, vanadium oxide, zirconium oxide, zinc oxide, germanium oxide and copper oxide.

In one embodiment of the present invention, the non-conductive material may be a porous diatomaceous earth shell.

In one embodiment of the present invention, the sulfur element or the sulfur compound and the nonconductor may be contained in a weight ratio of 4: 1 to 6: 1.

(A) mixing a sulfur element or a sulfur compound and an insulator material in a weight ratio of 4: 1 to 6: 1 and heating at a temperature of 150 to 160 ° C for 10 to 14 hours; And (b) heating the mixture heated in step (a) again at 240 to 260 ° C under nitrogen for 2 to 4 hours and cooling the mixture.

In one embodiment of the present invention, the sulfur-containing compound may be Li ₂ Sn (n? 1) or an organic sulfur compound.

In one embodiment of the present invention, the non-conductive material may be at least one selected from the group consisting of silica, alumina, titanium oxide, iron oxide, vanadium oxide, zirconium oxide, zinc oxide, germanium oxide and copper oxide.

In one embodiment of the present invention, the non-conductive material may be a porous diatomaceous earth shell.

The present invention also provides a positive electrode active material for a lithium-sulfur battery produced by the method of the present invention; bookbinder; And a cathode comprising a conductive material.

In one embodiment of the present invention, the anode comprises a sulfur element or a sulfur compound constituting a cathode active material for a lithium-sulfur battery; And an insulator; The conductive material; And a binder in a weight ratio of 5: 1: 1: 2, respectively.

Further, the present invention provides a positive electrode comprising: the positive electrode; A cathode arranged at a predetermined interval; A separation membrane disposed between the anode and the cathode; And an electrolyte filled between the anode and the cathode.

The present invention is the first to disclose that a non-conductive material as a cathode active material for a lithium-sulfur battery can be used as a support of sulfur. Specifically, when an insulator material is used as a diatomaceous earth silica shell, It is possible to obtain a sufficient electro-active effect on the side, and the diatomite silica shell It is made of natural minerals and it is composed of porous nano structure through self-assembly. It can easily carry soluble polysulfide ions, can improve cycle and rate performance, and can minimize sulfur sublimation during electrode drying process. There is an effect that the sulfur utilization can be increased and mass production of the electrode can be made at a low cost.

FIG. 1 is a schematic view showing a manufacturing process of a DS / S composite according to the present invention (FIG. 1A). FIG. 1B is a photograph of a DS / S composite according to the present invention observed by SEM. 1d and 1e are photographs of a low magnification and a high magnification observation of the DS / S composite of the present invention, and 1f to 1i are photographs of an electrolyte, a binder and G, h, and i represent Si, O, and S elements, respectively, of the surface of a DS / S composite containing conductive carbon.
2 shows a TEM image of a pure DS, wherein 2a is a low magnification photograph and 2b is a high magnification photograph.
Fig. 3 shows the results of the characterization of pure DS (DS itself) and DS / S composite, in which 3a shows the XRD diffraction pattern and 3b shows the TGA curve analysis result under a nitrogen atmosphere.
Figure 4 shows the nitrogen isotherm adsorption curve (4a) analysis and pore size distribution diagram (4b) for pure DS (DS itself) and DS / S composites.
5A and 5B are graphs showing results of electrochemical performance analysis for a sulfur battery and a DS / S battery, in which 5a and 5b are cycling at 1.8 V to 2.7 V at a room temperature for a pure sulfur battery 5a and a DS / S battery 5b 5c shows the rate-limiting performance of a DS / S cell at different C rates of 0.2 to 3C compared to a pure spheric cell, and 5d shows a discharge / charge curve for a DS / S cycle performance compared to a pure sulfur cell.
6 shows the results of an ex-situ EDS analysis of the DS / S battery of the present invention, wherein 6a shows the initial discharge curve of the DS / S battery at different cut-off voltages, 6b to 6d show different cut- That is, the result of analyzing the ratio of S / Si at OCV, 2.06V and 1.8V.
7 shows an SEM image of the DS / S composite electrode, and 7b to 7f are photographs showing Si, O, C and S elements, respectively. .
FIG. 8 shows the results of analyzing the characteristics of solid sulfur particles during electrode drying as a result of TGA curve analysis for the sulfur 8a to be used and the DS / S electrode 8b of the present invention.
9 is a schematic representation of the working principle of the DS / S composite (cathode active material) of the present invention in a lithium-sulfur battery system, wherein 9a is a DS / S composite having a thin sulfur layer produced by a melt- S composite (cathode active material), and 9b shows the solubilities of active sulfur molecules in a sulfur cell commonly used in the discharge process and a DS / S battery according to the present invention.

The present invention is a new method for supplementing the nonconductive state of sulfur in a lithium-sulfur battery, which is a new material capable of replacing a conductive porous carbon structure which has been conventionally used, and is characterized by providing a new use of an insulator material.

As previously mentioned in the prior art, sulfur is attracting attention as a cathode material of a lithium battery due to its low unit price, rich reserves, and high energy density. However, since the water-soluble polysulfide produced during the lithium-sulfur reaction exhibits high solubility in the electrolyte, irreversible characteristics are increased, and low lifetime and low output characteristics are encountered.

If the carbon / sulfur complex is synthesized by supporting sulfur on the porous carbon support, the output characteristics are improved. However, the carbon structure is complicated to synthesize and expensive to manufacture.

In particular, when the carbon / sulfur complex is used, the solubility of the water-soluble polysulfide increases as the reaction progresses, the leaching of the active material on the lithium metal surface increases, and the active substances in the nanometer mesopores are isolated do.

Therefore, the inventors of the present invention for the first time confirmed that a non-carbon non-carbon material can be used as the support of sulfur. When the non-conductor composite containing sulfur is used as the cathode active material, And that sulfur present inside and outside of the reaction can react well with the electrochemical reaction.

Accordingly, the present invention can provide a positive electrode active material for a lithium-sulfur battery, comprising a composite in which a sulfur element or a sulfur compound is supported on an non-conductive material.

The sulfur compounds usable for preparing the lithium-sulfur battery according to the present invention include, but are not limited to, Li ₂ Sn (n ≥1) or organic sulfur compounds, preferably Li ₂ Sn (n ? 1) can be selected from the group consisting of Li ₂ S ₃ , Li ₂ S ₄ , Li ₂ S ₆ and Li ₂ S ₈ .

The non-conductive material that can be used as the support of sulfur in the present invention is not limited thereto, but the non-conductive material may be silica, alumina, titanium oxide, iron oxide, vanadium oxide, zirconium oxide, zinc oxide, germanium oxide and copper oxide .

In one embodiment of the present invention, the non-conductive silica of the sulfur carrier is used, and a porous diatomaceous earth skin is preferably used.

The porous diatomite shell used in one embodiment of the present invention is a non-conductive porous silica material having a three-dimensional porous structure inside particles by self-assembling method and has a micron size There are many pores in the diatomite shell having a large number of pores and the surface is coated with not only sulfur but also the inside of the diatomite shell, the amount of sulfur can be significantly increased compared to the carbon structure.

Therefore, in the present invention, the nonconductor for use as a support of sulfur can be manufactured to have a structure having many pores so that sulfur can be effectively supported.

When the nonconductor according to the present invention is used as a sulfur bearing material, the sulfur element or the sulfur compound and the nonconductor are preferably used in a weight ratio of 4: 1 to 6: 1 to form a composite.

When the sulfur element or the sulfur compound and the non-sulfur compound are used at a ratio outside the above range, there is a problem that the electric property improving efficiency is poor and the electrical activation of the sulfur is also disadvantageous.

Further, the present invention can provide a method for producing a cathode active material for a lithium-sulfur battery using an insulator material as a sulfur bearing material, which method comprises (a) reacting a sulfur element or a sulfur- : 1 and heating at a temperature of 150 to 160 캜 for 10 to 14 hours; And (b) heating the mixture heated in step (a) again under nitrogen at a temperature of 240 to 260 ° C for 2 to 4 hours and cooling, and the method according to the present invention comprises the steps of .

The present invention also relates to a cathode active material for a lithium-sulfur battery produced by the method of the present invention; bookbinder; And a conductive material, wherein the anode is a sulfur element or a sulfur compound constituting a cathode active material for a lithium-sulfur battery; And an insulator; The conductive material; And a binder in a weight ratio of 5: 1: 1: 2, respectively.

Further, the present invention provides a positive electrode according to the present invention; A negative electrode disposed at a predetermined distance from the positive electrode; A separation membrane disposed between the anode and the cathode; And an electrolyte filled between the anode and the cathode.

In the lithium-sulfur battery provided in the present invention, since the diatomite-sulfur complex having a size of several microns is present in the electrode, the supply of active polysulfide can be smoothly performed, dissolution can be suppressed through absorption of water- It is possible to prevent the sulfur sublimation of the active material in the process, improve the lifetime and the speed characteristics of the battery, and have the advantage of simplifying the conventional lithium-battery manufacturing process through sulfur-sublimation control.

The positive electrode active material of the DS / S of the present invention used for the production of the lithium-sulfur battery of the present invention was found to be able to realize excellent performance in electrical characteristics. This was because (1) the diatomaceous earth shell DS ) Has a favorable structure for supporting sulfur, i.e., a well-ordered hierarchical pore structure, which can have a sulfur-containing ability of about 84%, and (2) the anode of the DS / S composite The active material shortens the reaction path and increases the contact area so that the sulfur can actively participate in the reaction during the electrochemical process of the lithium-sulfur battery, and (3) the sulfur sublimation can be reduced during the electrode drying process. 8 shows the TGA curve of the sulfur (a) and the DS / S electrode (b) of the present invention commercialized under the atmosphere at a temperature of 70 ° C., It was found that the DS / S electrode of the present invention significantly suppressed the sublimation of sulfur compared to sulfur. That is, a sulfur loss of 5% was observed in the commercialized sulfur, whereas a sulfur loss of 1.7% was observed in the DS / S electrode of the present invention.

Also, the DS / S electrode prepared in the present invention showed a cycle stability of 732 mAh / g even after 100 cycles. It can be seen that the DS can be used as a good adsorbent of soluble polysulfide generated during cycling.

Therefore, it is experimentally confirmed that the present invention can use an insulator material as a sulfur bearing material which can replace a conventional porous carbon structure which has been used to participate in an electrochemical reaction as an insulator.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for further illustrating the present invention, and the scope of the present invention is not limited to these examples.

< Example  1>

Preparation of Porous Diatomite Shell (DS) / Sulfur (S) Composite

The porous diatomite shell / sulfur complex according to the present invention was prepared by the following method. First, pure porous diatomaceous earth bark (purchased from Sigma-Aldrich) and sulfur (purchased from Sigma-Aldrich) were mixed in a weight ratio of 1: 5 (DS: S), ground and transferred to a teflon pot, Lt; / RTI &gt; for 12 hours. Subsequently, the heated mixture is further heated for 3 hours at a temperature of 250 ° C. in a nitrogen gas atmosphere, thereby allowing molten sulfur to be uniformly dispersed in the porous pores of the diatomite so that a DS / S complex having a higher purity can be obtained Respectively. The heated DS / S complex was then cooled. The process for producing the DS / S composite of the present invention is shown in FIG.

< Example  2>

Characterization of the DS / S complex prepared in the present invention

The morphological analysis and structural analysis of the inventive DS / S composite prepared in Example 1 above were analyzed using SEM (Hitachi, S-4800) and TEM (JEOL, FE-2010). After aging for 24 hours, the decomposed DS / S cathode material was confirmed by EDS analysis. Phase analysis of the material was performed using XRD (Rigaku, 1200) with Cu-Ka gamma and Ni-beta filters at 40 kV and 20 mA conditions. The amount of sulfur loaded on the DS / S complex was determined by analyzing with TGA (Bruker, TG-DTA2000SA) and the amount of sulfur lost on the electrode during the drying process was measured using 0.01 mg of Mettler Toledo XSE 105 DU, which is identifiable. The specific surface area was calculated using a nitrogen adsorption meter (Micromeritics, ASAP 2020). As a control group, only the non-sulfur-containing DS was analyzed in the same manner as above.

<2-1> Analysis by SEM (electron scanning microscope) and TEM (transmission electron microscope)

As a result of the morphological analysis by SEM analysis, when the diatomaceous earth (DS) was observed, it was confirmed that the DS type having hollow pores having many pore layers on the outer surface as shown in FIGS. 1B and 1C. Therefore, the present inventors have found that a DS having a porous surface can adsorb sulfur and soluble polysulfide with excellent efficiency. The disk-shaped siliceous DS of the present invention having a hierarchical nanostructure also has a large macroporous volume and multiple porosity correlated with 3D with a diameter of 14 to 28 um and a thickness of 1.1 to 1.9 um.

As a result of the TEM analysis, the DS used in the present invention is well aligned with porous structures of a large size (large macropores) (having a pore size of 200 to 320 nm) and small mesopores (having a pore size of 20 to 30 nm) (Fig. 2), and it was found that this structure can favorably carry sulfur and soluble polysulfide.

Also, during the DS / S composite preparation process of the present invention, solid sulfur was impregnated into the porous structure of DS in the melt diffusion step, which was confirmed by SEM image analysis of the DS / S composite. That is, in the photographs of d and e in FIG. 1, DS is impregnated with sulfur, and the surface of the DS is also coated with a sulfur layer.

Further, the present inventors prepared a DS / S cathode active material and conducted an EDS analysis to confirm the distribution of sulfur in the DS / S composite.

As a result of the analysis, it was found that the Si, O and S elements were uniformly and well distributed on the DS particles (Fig. 1 (f) to (i)). In FIG. 1, g, h and i are the results of checking Si, O and S elements, respectively, and f is the SEM image of the surface of the DS / S electrode containing electrolyte, binder and conductive carbon.

<2-2> X-ray diffraction (XRD) analysis

 X-ray diffraction patterns of DS / S complex, DS and S were analyzed.

As shown in FIG. 3, as shown in Fig. 3, the sulfur exhibited a very strong XRD peak as in the case of the crystalline orthorhombic structure, and the peak at 2θ = 22 ° of DS showed broad and weak peaks showing amorphous silica structure see. The DS / S complex exhibited relatively small diffraction peaks of sulfur compared to the original sulfur, indicating that crystalline sulfur particles were present in the DS / S complex (see FIG. 3a). These results have already been confirmed by the above SEM analysis results.

As a result of the TGA curve analysis, as shown in Fig. 3B, a single step weight loss result was shown in a temperature range of 200 to 350 DEG C, and a sulfur content was measured as 83.5 wt% based on the total weight loss value at 600 DEG C .

<2-3> Nitrogen isotherm adsorption curve analysis

Nitrogen isotherm adsorption curves were analyzed to analyze DS surface area and pore size distribution before and after loading sulfur. The pore structure of DS was confirmed by the nitrogen isotherm adsorption curve based on a BET specific area of 94 m ² / g and a total pore volume of 0.36 cm ³ / g.

As a result of the analysis, as shown in FIG. 4, the BET surface area and the total pore volume of the DS / S composite were reduced to 7.4 m ² / g and 0.04 cm ³ / g, respectively, by the injection of sulfur into the DS pore Because sulfur is loaded into the hierarchical pores of the DS and a thin layer of sulfur is formed on the surface of the DS.

Through the above nitrogen adsorption test and TGA analysis, the present inventors measured sulfur loading of multi pores of DS and sulfur coating of DS surface at about 52% and 48%, respectively.

&Lt; Example 3 >

Manufacture of cathodes electrodes

Sulfur slurry consisting of sulfur powder, ketjen black and polyethylene oxide (PEO), which are conductive materials, were added to acetonitrile in a weight ratio of 5: 1: 2, respectively, for 24 hours And then coated on a carbon-coated aluminum foil (Al foil). In addition, DS / S composite, ketjen black and polyethylene oxide (PEO) each having a weight ratio of DS and S of 1: 5 were mixed at a weight ratio of 1: 2 To dissolve in acetonitrile, and then the same procedure as in the preparation of the above-mentioned sulfur electrode was carried out. At this time, the amount of sulfur was the same for both electrodes, and the two electrodes were obtained by punching in the form of a round sheet using an electrode punching mechanism (MTI, 16 mm diameter) Lt; / RTI &gt;

<Example 4>

Electrical characterization

Electrical characterization was performed using a 2032 coin cell assembled in a glove box filled with lithium-metal and argon, and electrochemical measurements were performed on the counter electrode. The electrode was separated by a separator (Celgard 2400). The electrolyte used in the battery was 0.2 M LiNO ₃ , and DOL (1,3-dioxolane) and DME (dimethoxyethane) were mixed in a volume ratio of 1: M of lithium bis-trifluoromethanesulfonylimide was used as a mixed solution containing lithium bis-trifluoromethanesulfonylimide. The rate setting for the battery test is based on the sulfur content in the anode, and ¹ C corresponds to 1,675 mAg ^-1 . All cells were initially tested at 0.1 C and 2 cycles, and subsequent tests were tested at different C rates ranging from 0.2 to 3C. Charge and discharge behaviors of the cells were analyzed by a BaSyTec multi-channel battery tester at 0.1C rate and 1.8 ~ 2.7V voltage range. To analyze the electrical characteristics of the battery, electrodes were discharged and charged by 2 cycling at a low current density of 1 C, and the analysis was performed at a high current density. At this time, pure sulfur electrode using only sulfur was used as the control group.

As a result of the analysis, the primary and secondary discharge-charge curves of the pure sulfur electrode and the DS / S electrode were 1.8 V to 2.7 V (vs. Li / Li + at the 0.1 C rate (1 C = 1,675 mAh / g)) (see Figs. 5A and 5B). The pure sulfur anodes and DS / S cells exhibited electrochemical behavior at 0.1C rate, almost equal to discharge capacities of 1,122mAh / g and 1,173mAh / g, respectively. The DS / S anode also showed a high capacity of 900 mAh / g in the first 10 cycles at 0.2C.

From these results, the present inventors have found that the sulfur particles contained in the non-conducting DS / S complex can participate in the electrochemical reaction, and that the two discharged (high voltage) (2.4 V) and low As the conditions are clearly identified, it can be seen that the complex sulfur chemistry reacts the solid sulfur particles with high order polysulfides at higher voltages, and furthermore, at lower discharge voltages, the higher order polysulfides feed the electrons It was possible to characterize the reaction with low order polysulfide. On the other hand, two similar charge states were found in the reversible reaction, confirming that the low-order polysulfide generated in the discharge process was converted to the higher-order polysulfide, resulting in the participation of the sulfur present in and out of the insulator in the electrochemical reaction.

FIG. 5c shows the result of analyzing the discharge capacity ratio of pure sulfur and DS / S cells at various current densities. The DS / S battery showed improved rate-limiting performance at all experimental C rate compared to pure sulfur battery. DS / S showed 422mAh / g (45% retention vs at 0.2C) and 205mAh / g (45% retention vs at 0.2C) at the same C rate as 3C. In addition, after returning the current density from 3C to 0.2C which is the initial C rate in the 26th cycle, the discharge capacity was recovered from 0.2C to 92% of the initial capacity in the 5th cycle. These results indicate an improved reversibility of the lithium-sulfur battery. Therefore, it was found that the sulfur element or the sulfur compound can exhibit a high rate-limiting performance in a stable and well-adapted space in the hierarchical porous matrix of the DS / S composite.

The cycle performance measurements were performed after 0.2 C to 100 cycles for the two battery types. After 100 cycles, according to FIG. 5D, the DS / S anode showed a capacity decay of 0.26% per cycle and 77% (732 mAh / g), while the pure sulfur anode showed a capacity decay of 0.73% per cycle and a capacity of 48% (447 mAh / g) remained. In both batteries, the Coulomb effect was similar to 100% in most cycles.

These results show that the DS with hierarchical pore structure can improve the adsorption capacity so that the soluble sulfur intermediate generated during cycling can be localized and thus have a high rate capacity.

Therefore, the present inventors have found that the use of the DS / S complex is very simple and can improve the electrochemical performance of the lithium-sulfur battery in the rate-controlling capacity and the cycle stability.

In addition, electrochemical analysis of the DS / S complex was confirmed, i.e., the DS / S anode at three different cut-off voltages OCV, 2.06V and 1.8V during the initial discharge process was analyzed via ex-situ EDS.

As a result of the analysis, in the discharge state, the ratio of S to Si (S / Si) gradually decreased, that is, 0.93 at OCV, 0.52 at 2.06V and 0.38 at 1.8V / Li ⁺ ). From these results, the present inventors have found that there is still enough sulfur to be measured in the DS even after the discharge is completed, and that all the solid sulfur of the DS / S electrode can participate in the electrochemical reaction even during discharging I could. In addition, as shown in FIG. 7, the DS of the present invention plays a role as a good and good carrier for the soluble polysulfide ion generated during the discharge, as a result of the SEM image analysis and the EDS analysis of the DS / S electrode discharged at 0.2 C I can see that it can be done.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is obvious to those who have. Accordingly, it should be understood that such modifications or alterations should not be understood individually from the technical spirit and viewpoint of the present invention, and that modified embodiments fall within the scope of the claims of the present invention.

Claims (12)

A sulfur element or a sulfur compound is supported on the non-conductor material,
The sulfur element or the sulfur compound and the non-conductive material are contained in a weight ratio of 4: 1 to 6: 1,
Characterized in that the non-conductor material is selected from the group consisting of silica, alumina, titanium oxide, iron oxide, vanadium oxide, zirconium oxide, zinc oxide, germanium oxide, copper oxide and porous diatomaceous earth bark.
Cathode active material for lithium - sulfur battery. The method according to claim 1,
Wherein the sulfur-containing compound is Li ₂ Sn (n? 1) or an organic sulfur compound. delete delete delete (a) mixing a sulfur element or a sulfur compound and an insulator material in a weight ratio of 4: 1 to 6: 1 and heating at a temperature of 150 to 160 ° C for 10 to 14 hours; And
(b) heating the mixture heated in step (a) again under nitrogen at a temperature of 240 to 260 ° C for 2 to 4 hours and cooling;
Characterized in that the non-conductor material is selected from the group consisting of silica, alumina, titanium oxide, iron oxide, vanadium oxide, zirconium oxide, zinc oxide, germanium oxide, copper oxide and porous diatomaceous earth bark.
A method for producing a cathode active material for a lithium-sulfur battery. The method according to claim 6,
Wherein the sulfur-containing compound is Li ₂ Sn (n? 1) or an organic sulfur compound. delete delete A positive electrode active material for a lithium-sulfur battery produced by the method of claim 6; bookbinder; And an anode comprising a conductive material. 11. The method of claim 10,
The positive electrode may be a sulfur element or a sulfur compound constituting a positive electrode active material for a lithium-sulfur battery; And an insulator; The conductive material; And the binder are contained in a weight ratio of 5: 1: 1: 2, respectively. A positive electrode of claim 10;
A negative electrode disposed at a predetermined distance from the positive electrode;
A separation membrane disposed between the anode and the cathode; And
And an electrolyte filled between the anode and the cathode.

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