KR101852400B1 - Aluminum-ion capacitor having molybdenum disulphide electrode - Google Patents

Abstract

The present invention relates to an aluminum ion capacitor provided with a molybdenum disulfide electrode and to a super-capacitor configured to include: a separation film; an anode and a cathode disposed with the separation film interposed therebetween; and an electrolyte coming into contact with the anode and the cathode to store electric energy by an electric dual layer formed on a surface of an electrode. The anode is configured to include MoS_2, the cathode is composed of a material containing aluminum and the electrolyte contains aluminum ions, thereby forming and releasing the electric dual layer by charges contained in the electrolyte on a surface of the anode and inserting and separating the aluminum ions contained in the electrolyte in the cathode to store and discharge the electric energy. The present invention can configure the super-capacitor with enhanced energy density at a low price compared with a lithium ion capacitor. In addition, the present invention has high material stability compared with the lithium capacitor in the conventional art to have no limit on an electrode structure and to be able to adopt a structure which can lower manufacturing costs and enhance energy density and output density. Moreover, the present invention uses the MoS_2, not porous carbon as an electrode material of the anode to provide the aluminum ion capacitor with enhanced lifespan.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an aluminum ion capacitor having a molybdenum disulfide electrode,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super capacitor, and more particularly, to a super capacitor having an energy density increased through aluminum ions.

In general, supercapacitors are sometimes referred to as electric double layer capacitors (EDLC) or ultra-capacitors. Unlike batteries that utilize chemical reactions, supercapacitors are typically used for simple ion transport or surface chemical reactions at the electrode- Is an energy storage device that utilizes a charging phenomenon caused by a magnetic field.

Specifically, the supercapacitor is formed of an electrode attached to a conductor and an electrolyte solution impregnated in the electrode, and a pair of charge layers (electric double layer) having different signs are formed at the interface of the electrodes. These supercapacitors are capable of rapid charge / discharge, exhibit high charge / discharge efficiency, exhibit a semi-permanent cycle life characteristic without requiring maintenance because the deterioration due to repetition of charging / discharging operations is very small, Generation energy storage device that can be used.

These super capacitors are capable of rapid charging and discharging, have excellent cycle life as compared with secondary batteries, and have a wide temperature range. However, it has disadvantages that the energy density that can be stored is much lower than that of a secondary cell. In order to compensate for these disadvantages, various types of compensations have been carried out. Recently, one electrode stores electric energy by forming an electric double layer of a supercapacitor, and the other electrode has a lithium ion insertion / Improvement technology of supercapacitor was developed. Such a supercapacitor, which is also called a lithium ion capacitor, is expensive, and since it is difficult to form an electrode in which lithium ions are inserted and removed, the super capacitor is lost in price competitiveness and is not put into practical use. Lead oxide capacitors using lead oxides that are cheaper than lithium have been developed as similar forms, but they are difficult to put to practical use because they use lead, which is a toxic substance.

Korean Patent No. 10-1137723

SUMMARY OF THE INVENTION It is an object of the present invention to provide a supercapacitor using relatively low cost and environmentally friendly aluminum ions.

According to an aspect of the present invention, there is provided an aluminum ion capacitor having a molybdenum disulfide electrode, comprising: a separator; A cathode and a cathode arranged with the separator interposed therebetween; And an electrolyte in contact with the positive electrode and the negative electrode, the supercapacitor storing electric energy by an electric double layer formed on the surface of the electrode, wherein the positive electrode comprises MoS ₂ , and the negative electrode comprises aluminum Wherein the electrolyte comprises aluminum ions and the formation and release of an electric double layer are carried out by the electric charge contained in the electrolyte on the surface of the anode. In the cathode, insertion and removal of aluminum ions contained in the electrolyte Is performed to store and discharge electrical energy.

The inventor of the present invention invented and applied an aluminum ion capacitor that exhibits sufficient energy storage performance while having a lower manufacturing cost than a lithium ion capacitor having a high manufacturing cost. However, in the case of using porous carbon such as activated carbon, carbon nanotube, and graphene, which are used in lithium ion capacitors and the like as the electrode material constituting the anode, the performance is gradually lowered in the course of repeated charging and discharging, exist. This decrease in lifetime was more serious in the aluminum ion capacitor in which the aluminum ion acts than in the case of the lithium ion, and this was the biggest problem in the practical use of the aluminum ion capacitor. Accordingly, the inventor of the present invention has developed an aluminum ion capacitor of the present invention in which MoS ₂ (molybdenum disulphide, molybdenum disulfide) is applied as an electrode material constituting the anode in place of the porous carbon.

Particularly, MoS ₂ is preferably a nanosheet in which the microstructure is a two-dimensional planar structure, and exhibits a metal characteristic when the crystal structure is a 1T phase (1T phase) having a tetragonal system symmetry structure.

At this time, the cathode is preferably an aluminum foil. Since aluminum is a stable material, unlike a conventional lithium ion capacitor, the aluminum ion capacitor of the present invention can easily manufacture an anode because an aluminum foil can be used as a cathode. In addition, there is a limitation in increasing the energy density by using a conventional lithium ion capacitor doped with lithium. However, since the aluminum ion capacitor of the present invention can use aluminum foil as a cathode, there is an advantage that such limitation can be overcome.

And the cathode may be one of the shell particles with aluminum foam, aluminum powder and aluminum coating. As described above, since aluminum is a stable material, there is an advantage that an aluminum cathode can be formed in various forms, such as a shell having an aluminum foam, an aluminum powder and an aluminum coating layer, if necessary. The material containing aluminum may be not only aluminum itself but also alloys of aluminum and copper, magnesium, manganese, silicon, titanium, zinc and the like.

The current collector may be a structure having a positive electrode or a negative electrode, and the current collector may be a base for forming the positive electrode or the negative electrode. As the material of the current collector, carbon materials such as graphite having high conductivity and various metal materials can be applied. Specific metal materials include gold, nickel, aluminum, titanium, stainless steel, chrome, copper and the like.

As the electrolyte containing aluminum ions, an ionic liquid electrolyte, an organic electrolyte, an aqueous electrolyte or the like can be used. The ionic liquid electrolyte is a case obtained by dissolving an aluminum salt, such as AlCl ₃ in the ionic liquid, for example, the ionic liquid is [EMIM] it is possible to dissolve the AlCl ₃ to the Cl (1-Ethyl-3- methylimidazolium chloride) And includes aluminum ions, such as alkylimidazolium aluminates, alkylpyridinium aluminates, alkylfluoropyrazolium aluminates, alkyltriazolium aluminates, For example, aralkylammonium aluminates, dialkylpipendinium aluminates, alkylalkoxyammonium aluminates, aralkylphosphonium aluminates, alkylsulfonium aluminum oxides, Aralkylsulfonium aluminates, ethylmethylimidazolium tetrachloroaluminum Ethylmethylimidazolium tetrachloroaluminate and the like. As the organic electrolyte, AlCl ₃ and Aluminum salts such as Al (NO ₃ ) ₃ are reacted with an organic solvent such as propylene carbonate, acetonitrile, ethylene carbonate, dimethylcarbonate, ethyl methyl carbonate, diethyl carbonate Diethyl carbonate, methyl tert-butyl ether, propylene glycol, and the like. As the aqueous electrolyte, an aqueous solution of AlCl ₃ , Al (NO ₃ ) _3, or the like is usable.

An aluminum ion capacitor having a molybdenum disulfide electrode according to another aspect of the present invention includes: a separator; A cathode and a cathode arranged with the separator interposed therebetween; And an electrolyte in contact with the anode and the cathode, wherein the electrolyte comprises aluminum ions, the anode comprises MoS ₂ , the cathode is a material capable of inserting and desorbing aluminum ions, An electric double layer is formed and released by the charge contained in the electrolyte on the surface of the anode, and insertion and desorption of aluminum ions contained in the electrolyte are performed in the cathode to store and discharge electric energy .

The present invention is characterized in that an electric double layer is formed in the anode, and insertion and desorption of aluminum ions are performed in the cathode to store electric energy. Thus, various materials can be used for the insertion and desorption of aluminum ions . For example, graphitic carbon, which is a crystalline carbon, or graphite doped with aluminum can be used to constitute a positive electrode capable of intercalation and deintercalation of aluminum ions, and an oxide such as silicon and titanium oxide as an insertion compound, A cathode capable of inserting and desorbing aluminum ions can be constituted by using a sulfide such as benzene sulfide or the like.

The present invention configured as described above has the effect of forming a supercapacitor having a sufficient energy density at a lower cost than the lithium ion capacitor.

In addition, since the material stability is higher than that of the conventional lithium ion capacitor, there is no restriction on the electrode structure, so that a manufacturing cost is low and a structure capable of increasing energy density and power density can be freely adopted.

Furthermore, by using MoS ₂ that is not porous carbon as the electrode material of the anode, it is possible to provide an aluminum ion capacitor with improved lifetime.

1 is a schematic view showing a structure of an aluminum ion capacitor according to an embodiment of the present invention.
FIG. 2 is a graph illustrating a result of measuring the capacitance of the aluminum ion capacitor according to the embodiment of the present invention.
Fig. 3 shows the result of calculating the specific capacity per area based on the non-capacity measurement result of Fig.
FIG. 4 shows the results of calculating the capacitance per weight of all the electrodes based on the results of the non-capacitance measurement of FIG.
5 shows the results of calculating the specific capacity per unit weight of MoS ₂ contained in the anode.
6 shows a cyclic voltage-current curve measured for an aluminum ion capacitor according to the present embodiment.
FIGS. 7 and 8 show a cyclic voltage-current curve measured while changing a scanning speed for an aluminum ion capacitor according to an embodiment of the present invention.
9 and 10 are graphs of constant current charge / discharge for an aluminum ion capacitor according to the present embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, embodiments of the present invention will be described in detail.

1 is a schematic view showing a structure of an aluminum ion capacitor according to an embodiment of the present invention.

The aluminum ion capacitor of the present embodiment is composed of the anode 10 coated on the current collector 40 and the cathode 20 opposed to the anode 10 and the separator 30 disposed between the anode 10 and the cathode 20, The electrolyte (not shown) is filled.

The aluminum ion capacitor of this embodiment uses a glass fiber separator as the separator 30, and an aluminum foil is used as the cathode 20. The collector is attached to a collector made of gold although not shown.

A slurry containing MoS ₂ was applied to the current collector 40 made of gold using the anode 10 and used.

MoS ₂ is a bulk (lump) state of MoS ₂ into the two-dimensional of the 3㎖-butyl lithium in the form of nanosheets in the inert gas atmosphere of argon to make the bulk of MoS ₂ powder 0.3g, the temperature is raised to 60 ℃ 48 Lt; / RTI > The mixture was filtered and washed with hexane to remove residual butyllithium. In this process, lithium is intercalated into the MoS ₂ powder, and the resulting mixture is put into water at a rate of 1.5 mg / ml, and ultrasonic waves are applied for 1 hour to peel the MoS ₂ into a two-dimensional nanosheet form. And centrifuged to remove lithium cations and bulk materials that have not been peeled off. The suspended material was filtered through a nitrocellulose membrane having a cavity of 25 nm in diameter and then dried to obtain a powdered two-dimensional nanosheet-shaped MoS ₂ .

MoS ₂ powder of 2-dimensional nanosheet type prepared by the above-mentioned method, 85 wt% of Super-P, 7 wt% of carboxymethyl cellulose (CMC), and 3 wt% of styrene-butadiene rubber (SBR) butadiene rubber was cast in a current collector 40 made of gold and dried to form the anode 10, and the area of the coated anode was 2.54 cm ² .

The aluminum foil used as the cathode 20 has a thickness of 2 mu m. Conventionally, in a super capacitor using lithium ion, lithium foil itself can not be used as a negative electrode due to lithium stability problem, but since aluminum is a stable material, the aluminum ion capacitor of this embodiment can use aluminum foil as a negative electrode, And it is advantageous that a cathode made of an aluminum material can be formed in various forms as needed.

Finally, AlCl ₃ was dissolved in an ionic liquid [EMIM] Cl (1-Ethyl-3-methylimidazolium chloride) as an electrolyte to be filled in the anode 10 and the cathode 20. Aluminum ions are dispersed in the electrolyte. In the aluminum cathode 20, aluminum ions are inserted and desorbed. In the anode 10, an electric double layer is formed by electrons contained in the electrolyte to store electric energy .

The electrochemical characteristics of the aluminum ion capacitor of this example thus configured were measured.

FIG. 2 is a graph illustrating a result of measuring the capacitance of the aluminum ion capacitor according to the embodiment of the present invention.

The capacitance of the aluminum ion capacitor was measured while the scanning speed was changed from 1 to 100 mV / S at 2V. In the aluminum ion capacitor of Example 2, the cost amount decreased with the increase of the scanning speed.

Fig. 3 shows the result of calculating the specific capacitance per area based on the specific capacitance measurement result of Fig. 2. Fig. 4 shows the result of calculating the specific capacitance per weight of all electrodes based on the specific capacitance measurement result of Fig. Is a result of calculating the specific capacity per weight of MoS ₂ contained in the anode.

FIG. 3 shows the results of calculation based on the area of the anode applied to the current collector of 2.54 cm ² , FIG. 4 shows the results of calculation based on the weight of the anode of 1.6631 mg and the weight of the cathode of 1.4689 mg, Fig. 5 shows the result of calculation with the ratio of MoS ₂ (85 wt%) contained in the anode.

From the results shown, it can be seen that the aluminum ion capacitor of this embodiment has a considerably high energy density. These results show that a supercapacitor can be manufactured which exhibits a relatively low material cost and a sufficient energy density even in a manufacturing process as compared with a conventional lithium ion capacitor using lithium ions. In addition, it can be confirmed that the electric characteristics are superior to those in the case of using a porous carbon material anode.

6 shows a cyclic voltage-current curve measured for an aluminum ion capacitor according to the present embodiment.

The cyclic voltammogram (CV curve) measures the current according to the potential while changing the potential of the electrode from the initial potential to the specific potential and then changing it back to the original potential. It shows the behavior at discharge. The scanning current was fixed at 10 mV / S, and the current corresponding to the potential was measured while the voltage range was changed from 0 V to 1.0-2.1 V.

The shape shown in the figure shows a typical CV curve shape in a supercapacitor. This is because the aluminum ion capacitor of this embodiment has an electric double layer formed on the anode and the insertion and desorption of aluminum ions on the cathode are performed. However, Means a kind of super capacitor representing the shape.

In addition, the area of the closed curve increases as the applied potential increases, which is consistent with the results of the above non-capacitance measurement since the cost is increased.

7 and 8 show a cyclic voltage-current curve measured while changing the scanning speed for an aluminum ion capacitor according to an embodiment of the present invention.

The current-voltage curve was drawn while varying the voltage to 2 V and the scanning speed was varied from 1 to 100 mV / S. 8 is a graph showing a case where the scanning speed is in the range of 1 to 20 mV / S. The cyclic voltage-current curve for the aluminum ion capacitor of this embodiment shows the CV curve that appears in the supercapacitor as described above, and the area of the closed curve increases as the scanning speed increases.

9 and 10 are graphs of constant current charge / discharge for an aluminum ion capacitor according to the present embodiment.

The voltage range in which charging and discharging are performed is fixed to 0 to 2 V, FIG. 9 shows a charging / discharging current of 400 μA, and FIG. 10 shows a charging / discharging current of 4 mA. As shown in the figure, the aluminum ion capacitor according to the present embodiment shows a typical triangular charging / discharging curve characteristic of an ideal capacitor, and it can be confirmed that charging and discharging are performed stably even in cycle repetition.

As described above, although the aluminum ion capacitor using MoS ₂ as the electrode material of the anode of the present embodiment has a simple structure using aluminum which is lower in cost than the conventional lithium ion capacitor, It can be confirmed that the amount of money has a sufficiently suitable value as the energy storage device. In addition, it is confirmed that the anode electrode material has superior characteristics to the aluminum ion capacitor using the porous carbon as the anode electrode material.

Since the aluminum ion capacitor of this embodiment has excellent cycle life and excellent energy density, it can be used as an energy storage source of an energy storage system (ESS) or can constitute a very small auxiliary battery.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Those skilled in the art will understand. Therefore, the scope of protection of the present invention should be construed not only in the specific embodiments but also in the scope of claims, and all technical ideas within the scope of the same shall be construed as being included in the scope of the present invention.

10: anode
20: cathode
30: Membrane
40: The whole house

Claims (10)

Separation membrane;
A cathode and a cathode arranged with the separator interposed therebetween; And
An aluminum ion capacitor which is a sub-concept of a supercapacitor which comprises an anode and an electrolyte in contact with the cathode, and stores electric energy by an electric double layer formed on a surface of the electrode,
Wherein the anode comprises MoS ₂ , the cathode is made of aluminum, the electrolyte comprises aluminum ions,
Discharging behavior of the electric double layer by the charge contained in the electrolyte is performed on the surface of the anode and insertion and desorption of aluminum ions contained in the electrolyte is performed in the cathode, An aluminum ion capacitor.
The method according to claim 1,
Wherein the MoS ₂ contained in the anode has a crystal structure of 1T phase.
The method of claim 2,
Wherein the microstructure of MoS ₂ is a nanosheet shape.
The method according to claim 1,
Wherein the cathode is an aluminum foil.
The method according to claim 1,
Wherein the cathode is one of shell particles having an aluminum foil, an aluminum powder and an aluminum coating layer.
The method according to claim 1,
And a current collector is attached to the positive electrode.
The method according to claim 1,
And a current collector is attached to the negative electrode.
Separation membrane;
A cathode and a cathode arranged with the separator interposed therebetween; And
And an electrolyte in contact with the anode and the cathode,
Wherein the electrolyte comprises aluminum ions,
Wherein the anode comprises MoS ₂ ,
The negative electrode is a material capable of inserting and desorbing aluminum ions,
Discharging behavior of the electric double layer by the charge contained in the electrolyte is performed on the surface of the anode and insertion and desorption of aluminum ions contained in the electrolyte is performed in the cathode, An aluminum ion capacitor.
The method of claim 8,
Wherein the MoS ₂ contained in the anode has a crystal structure of 1T phase.
The method of claim 9,
Wherein the microstructure of MoS ₂ is a nanosheet shape.

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