KR20180050776A - Energy storage devices including the electrode, the electrode manufacturing method and the electrode to improve the electrochemical performances - Google Patents

Abstract

The present invention relates to an electrode for improving characteristics, a manufacturing method thereof, and an energy storage device including the same. A technical point includes the steps of: manufacturing an active material/carbon material composite by mixing an active material with a carbon material; manufacturing a manganese oxide/graphene oxide (MnO2/GO) electrode catalyst; and forming the electrode by mixing the active material/carbon material composite with the electrode catalyst. Accordingly, the composite of the active material for a hybrid capacitor and the carbon material for enhancing conductivity is formed and MnO2/GO that is the electrode catalyst is mixed therewith to improve electrode characteristics.

Description

[0001] The present invention relates to an electrode for improving electrochemical characteristics, an electrode manufacturing method, and an energy storage device including an electrode,

The present invention relates to an electrode for improving electrochemical characteristics, an electrode manufacturing method, and an energy storage device including an electrode. More particularly, the present invention relates to an energy storage device for forming a composite of an active material for a hybrid capacitor and a carbonaceous material for increasing conductivity, To an electrode for improving electrochemical characteristics of forming an electrode by mixing MnO ₂ / GO which is an electrode catalyst, an electrode manufacturing method, and an electrode.

In order to achieve miniaturization and long-term continuous use of portable electronic devices in accordance with the improvement of industrial development and living standards, there is a demand for light weight and low power consumption of parts, and a high performance energy storage device capable of realizing small size and high capacity. Recently, an energy storage device such as a lithium ion battery, an electric double layer capacitor (EDLC), a super capacitor or a hybrid capacitor has been used as an electric vehicle, a battery electric power storage system And is used as a small-sized, high-performance energy source such as a large-capacity power storage battery and a portable electronic device such as a mobile phone, a camcorder, and a notebook computer. However, despite the high energy density, the lithium ion battery has a disadvantage in that the charging efficiency is reduced due to the low output characteristics and the number of charge / discharge cycles of about 1000 times, and that the lithium ion battery should be replaced after 2 to 3 years of use. In addition, electric double layer capacitors have high wireless charging efficiency and long term reliability for more than 10 years due to high power and high charge / discharge frequency, but because of low energy density, they have small capacity for one charge and they are of low commercial value. Therefore, in order to secure a high wireless charging efficiency and long-term reliability, it is necessary to develop a hybrid capacitor having advantages of an electric double layer capacitor and a secondary battery.

Hybrid capacitors are fusion energy storage devices that combine the output characteristics of an electric double layer capacitor and the energy characteristics of a secondary battery. The hybrid capacitor has both advantages of an electric double layer capacitor and advantages of a secondary battery. In recent years, the necessity of developing such a capacitor Is emerging. Hybrid capacitors are mainly composed of ruthenium oxide (RuO ₂ ), manganese oxide (MnO ₂ ), nickel oxide (Ni (OH) ₂ ), tin oxide (SnO ₂ ), molybdenum oxide (Mo ₂ N) Transition metal oxides such as rid (TiN), vanadium oxide (V ₂ O ₅ ), ferrite (MnFe ₂ O ₄ ), tantalum oxide (Ta ₂ O ₅ ) These active materials have been widely used due to their high theoretical capacity, stable electrochemical reactions, excellent speed performance, and structural stability in alkaline electrolytes.

However, when these active materials are used alone, they are limited in commercialization due to the problems of output characteristics, cycle characteristics, high cost, and lack of high catalytic activity. Therefore, it is necessary to develop a composite material for improving the properties of the active materials.

Korea Patent Office Registration No. 10-0856286 Korea Patent Office Registration No. 10-0833041 Korea Patent Office Registration No. 10-0571267

Accordingly, an object of the present invention is to provide an electrode for improving the electrochemical characteristics of forming a composite of an active material for a hybrid capacitor and a carbonaceous material for increasing conductivity and forming an electrode by mixing MnO ₂ / GO, which is an electrode catalyst, An electrode manufacturing method, and an electrode.

The above object can be accomplished by a process for producing a manganese oxide / graphene oxide (MnO ₂ / GO) electrode catalyst, comprising the steps of: preparing an active material / carbon composite by mixing an active material and a carbonaceous material; And forming an electrode by mixing the active material / carbonaceous composite and the electrode catalyst. The present invention also provides a method of manufacturing an electrode for improving electrochemical characteristics.

Here, the active material is ruthenium oxide (RuO _2), manganese oxide (MnO _2), nickel oxide (Ni (OH) _2), tin oxide (SnO _2), molybdenum oxide (Mo ₂ N), titanium knit Wherein the carbon material is selected from the group consisting of ruthenium (TiN), vanadium oxide (V ₂ O ₅ ), ferrite (MnFe ₂ O ₄ ), tantalum oxide (Ta ₂ O ₅ ) Graphite, graphene, graphene oxide (GO), reduced graphene oxide (RGO), carbon nano tube, carbon fiber, , A conducting polymer, an aerogel, and mixtures thereof.

The mixture ratio of the active material / carbonaceous material and the electrode catalyst is preferably 95: 5 by weight.

The above-described object is achieved by a semiconductor device comprising: a substrate; And an electrode layer composed of an active material / carbonaceous composite laminated on the substrate and a manganese oxide / graphen oxide (MnO ₂ / GO) electrode catalyst.

Here, the active material / carbonaceous composite is preferably an? -Nickel hydroxide / graphen oxide composite (? -Ni (OH) ₂ / GO).

Further, the active material is ruthenium oxide (RuO _2), manganese oxide (MnO _2), nickel oxide (Ni (OH) _2), tin oxide (SnO _2), molybdenum oxide (Mo ₂ N), titanium knit Wherein the carbon material is selected from the group consisting of ruthenium (TiN), vanadium oxide (V ₂ O ₅ ), ferrite (MnFe ₂ O ₄ ), tantalum oxide (Ta ₂ O ₅ ) Graphite, graphene, graphene oxide (GO), reduced graphene oxide (RGO), carbon nano tube, carbon fiber, , A conducting polymer, an aerogel, and mixtures thereof.

The above objects are further accomplished by a cathode active material comprising a cathode comprising an active material / carbonaceous composite and a manganese oxide / graphene oxide (MnO ₂ / GO) electrode catalyst as a cathode active material; An anode including reduced graphene oxide (RGO) as a negative electrode active material; And an electrolyte solution in which the anode and the cathode are immersed.

According to the structure of the present invention described above, a composite material of an active material for a hybrid capacitor and a carbon material for increasing conductivity can be formed, and MnO ₂ / GO, which is an electrode catalyst, can be mixed with the carbon material to improve the electrode characteristics .

1 is a flowchart of an electrode manufacturing method for improving electrochemical characteristics according to an embodiment of the present invention,
2 is a graph showing the impedance of the comparative example and the embodiment,
3 is a graph showing output characteristics according to applied current densities of Comparative Examples and Examples.

Hereinafter, an electrode for improving electrochemical characteristics, an electrode manufacturing method, and an energy storage device including an electrode according to embodiments of the present invention will be described in detail with reference to the drawings.

The electrode comprises a substrate, and an electrode layer comprising an active material / carbon composite and a manganese oxide / graphene oxide (MnO ₂ / GO) electrode catalyst deposited on top of the substrate. Here, the active material / carbon composite material is preferably an? -Nickel hydroxide / graphen oxide composite (? -Ni (OH) ₂ / GO). Also, the energy storage device of the present invention including an electrode includes a positive electrode containing a positive electrode active material and a manganese oxide / graphite oxide (MnO ₂ / GO) electrode catalyst as a cathode active material, a reduced graphene oxide oxide, RGO) as a negative electrode active material, and an electrolyte solution in which the positive electrode and the negative electrode are immersed.

As shown in FIG. 1, an active material / carbon composite is prepared by mixing an active material and a carbonaceous material (S1).

The active materials used in the hybrid capacitors are various, but the active material / carbon composite is prepared by mixing active materials having high theoretical capacity, stable electrochemical reaction, excellent speed performance and structural stability in an alkaline electrolyte and carbon materials.

The active material may be at least one selected from the group consisting of ruthenium oxide (RuO ₂ ), manganese oxide (MnO ₂ ), nickel oxide (Ni (OH) ₂ ), tin oxide (SnO ₂ ), molybdenum oxide (Mo ₂ N), titanium nitride ), Vanadium oxide (V ₂ O ₅ ), ferrite (MnFe ₂ O ₄ ), tantalum oxide (Ta ₂ O ₅ ), and mixtures thereof. In the case of carbon materials, carbonaceous materials having functional groups are mixed to improve conductivity, which is mixed with active materials to increase conductivity. These carbon materials include activated carbon, graphite, graphene, graphene oxide (GO), reduced graphene oxide (RGO), carbon nano tube ), A carbon fiber, a conducting polymer, an aerogel, and a mixture thereof.

MnO ₂ / GO electrode catalyst is prepared (S1 ').

Separately from step S1, a manganese oxide / graphene oxide (MnO ₂ / GO) electrode catalyst is prepared. As a method for preparing the MnO ₂ / GO electrode catalyst, graphene oxide and MnCl ₂ .4H ₂ O are mixed in a solvent, potassium permanganate (KMnO ₄ ) is added thereto and stirred again to obtain an electrode catalyst. At this time, the stirring temperature is preferably 50 to 100 ° C. If the stirring temperature is less than 50 ° C., the reaction may not proceed smoothly. If the stirring temperature exceeds 100 ° C., the solvent may evaporate, 100 < 0 > C.

An electrode is formed by mixing an active material / carbon composite and an electrode catalyst (S2).

The active material / carbon composite prepared through the step S1 and the electrode catalyst prepared through the step S1 'are mixed with a conductive material and a binder, and then coated on the substrate to form an electrode. Here, it is most preferable that the mixing ratio of the composite used as the active material and the electrode catalyst is in a ratio of the composite: electrode catalyst = 95: 5, but is not limited thereto. Here, as a method of applying the composite and the electrode catalyst to the substrate, it is preferable that the method comprises forming a mixture of the composite and the electrode catalyst, and immersing the substrate in the mixture to dip coating the substrate. The mixture can then be dried and pressed at high temperature to produce electrodes with the substrate and the mixture firmly fixed.

Hereinafter, embodiments of the present invention will be described in more detail.

≪ Comparative Example >

1) Production of active material

First, in a reactor equipped with an α-nickel hydroxide / graphene oxide complex (α-Ni (OH) ₂ / GO) synthesis method, 500 ml of DI water was charged. To the reactor were added 18 g of α-nickel hydroxide of nano size and 18 g of graphene oxide, 2 g of ultrasonication is applied for 2 hours, and a homogenizer is treated at 20,000 rpm for 30 minutes to prepare a dispersion solution. This is dried to obtain a sample of a-nickel hydroxide / graphen oxide composite in powder state.

2) Manufacture of anode

α-Ni (OH) ₂ / GO composite was used as a cathode active material, and the composition of the slurry electrode was mixed in an active material: conductive material: binder = 89: 6: 5 weight ratio. The binder was prepared by dissolving 0.3 g of carboxymethylcellulose (CMC) in 9.7 ml of deionized water, and then 0.6 g of each of carbon black and CoO as conductive materials was ultrasonicated. After the ultrasonic treatment, 16.91 g of the cathode active material was added, and the mixture was treated with a thinky mixer for 20 minutes. Then, to aid dispersion of the active material, conductive material and binder, ultrasonic treatment was carried out using a homogenizer Respectively. Finally, styrene butadiene rubber (SBR) was added to adjust the viscosity of the slurry to 1000 to 1500 mPa · S. The slurry was dip coated in a Ni foam having a thickness of 1 mmT, and the electrode was then dried in a vacuum oven at 100 캜. After the electrode was dried, the electrode was pressed with a hot roll press at 80 DEG C so that the thickness of the electrode was 500 mu m.

3) Cathode manufacturing

Reduced graphene oxide (RGO) was used as the negative electrode active material, and the composition of the slurry electrode was mixed at a weight ratio of active material: conductive material: binder = 82: 8: 10. The binder was ultrasonicated by adding 1.6 g of carbon black as a conductive material to 0.5 g of polytetrafluoroethylene (PTFE) preliminarily stretched in a solution of 0.3 g of carboxymethylcellulose in 9.7 ml of deionized water. After the ultrasonic treatment, 16.4 g of active material was added, and the mixture was treated with a mixer for 20 minutes. Then, the mixture was treated with an ultrasonic processor or a homogenizer for 10 minutes to aid dispersion of the active material, conductive material and binder. Finally, SBR was added to adjust the viscosity of the slurry to 1000 to 1500 mPa · S. The slurry was dip coated in a nickel foam having a thickness of 1.8 mmT, and the electrode was then dried in a vacuum oven at 100 캜. After drying of the electrode, the electrode was pressed with a hot roll press at 80 DEG C so that the thickness of the electrode was 900 mu m.

≪ Example 1 >: Electrode Fabrication

1) Production of active material

First, in a reactor equipped with an α-nickel hydroxide / graphene oxide complex (α-Ni (OH) ₂ / GO) synthesis method, 500 ml of DI water was charged. To the reactor were added 18 g of α-nickel hydroxide of nano size and 18 g of graphene oxide, 2 g of ultrasonication is applied for 2 hours, and a homogenizer is treated at 20,000 rpm for 30 minutes to prepare a dispersion solution. This is dried to obtain a sample of a-nickel hydroxide / graphen oxide composite in powder state.

2) Electrode catalyst preparation

5.2 g of graphene oxide is added to 100 ml of isopropyl alcohol, the homogenizer is treated at 10,000 rpm for 10 minutes, and then 15.6 g of MnCl ₂ .4H ₂ O is added. For dispersion, the homogenizer is further treated at 10,000 rpm for 20 minutes and treated with ultrasonication for 20 minutes to form a first mixed solution. Then, a solution obtained by dissolving 7.8 g of potassium permanganate (KMnO ₄ ) in 250 ml of Di water is added to the reactor, and the temperature is raised to 80 ° C. and stirred to form a second mixed solution. The first mixed solution and the second mixed solution were put together in a reactor, stirred at a temperature of 80 캜 for 2 hours, and then cooled down. When the reaction is completed, it is washed several times with distilled water through a centrifuge and dried at 80 ° C to obtain an electrode catalyst.

3) Anode manufacturing

α-Ni (OH) ₂ / GO composite was used as a cathode active material, and the composition of the slurry electrode was mixed in an active material: conductive material: binder = 89: 6: 5 weight ratio. The binder was prepared by dissolving 0.3 g of carboxymethylcellulose (CMC) in 9.7 ml of deionized water, and then 0.6 g of each of carbon black and CoO as conductive materials was ultrasonicated. After the ultrasonic treatment, 16.91 g of the cathode active material and 0.89 g of MnO ₂ / GO as the electrode catalyst were treated with a mixer for 20 minutes. Then, to aid dispersion of the active material, conductive material and binder, an ultrasonic processor or homogenizer And treated for 10 minutes. Finally, styrene butadiene rubber (SBR) was added to adjust the viscosity of the slurry to 1000 to 1500 mPa · S. The slurry was dip coated in a Ni foam having a thickness of 1 mmT, and the electrode was then dried in a vacuum oven at 100 캜. After the electrode was dried, the electrode was pressed with a hot roll press at 80 DEG C so that the thickness of the electrode was 500 mu m.

4) Negative electrode manufacturing

Reduced graphene oxide (RGO) was used as the negative electrode active material, and the composition of the slurry electrode was mixed at a weight ratio of active material: conductive material: binder = 82: 8: 10. The binder was ultrasonicated by adding 1.6 g of carbon black as a conductive material to 0.5 g of polytetrafluoroethylene (PTFE) preliminarily stretched in a solution of 0.3 g of carboxymethylcellulose in 9.7 ml of deionized water. After the ultrasonic treatment, 16.4 g of active material was added, and the mixture was treated with a mixer for 20 minutes. Then, the mixture was treated with an ultrasonic processor or a homogenizer for 10 minutes to aid dispersion of the active material, conductive material and binder. Finally, SBR was added to adjust the viscosity of the slurry to 1000 to 1500 mPa · S. The slurry was dip coated in a nickel foam having a thickness of 1.8 mmT, and the electrode was then dried in a vacuum oven at 100 캜. After drying of the electrode, the electrode was pressed with a hot roll press at 80 DEG C so that the thickness of the electrode was 900 mu m.

Example 2: Cell preparation

The electrodes prepared in Example 1 were cut to 2.5 x 2.5 cm ² and stacked in the order of anode / separator / cathode by a cellulose-based separator. Then, the electrodes were placed in a Teflon cell, and an electrolyte injector Was impregnated with a 6M potassium hydroxide (KOH) electrolyte and vacuum sealed to prepare a cell.

≪ Example 3 >: Measurement of charging / discharging capacity

The charging and discharging capacities of the hybrid capacitors were charged and discharged by a constant current method in a charge and discharge tester (MACCOR, model series series 4000). The driving voltage was 0.8 to 1.6 V and the applied current density was ² mA / cm ² . The charging / discharging capacity of the hybrid capacitor was calculated by the following Equation 1 in the time-voltage curve in the fifth constant current discharge.

<Formula 1>

C (capacitance, F) = dt I / Dv

Example 4: Impedance measurement

In the case of the impedance of the hybrid capacitor cell, after the charge / discharge test, the frequency range was 1 to 1 MHz and the amplitude was 10 mV, and the 1 kHz resistance was measured. Fig. 2 shows the impedance results for comparing the cell resistances of the embodiment and the comparative example. The larger the slope of the graph, the smaller the contact resistance. Therefore, it can be seen from the fact that the slope of the comparative example is larger than that of the examples, the contact resistance is improved compared with the comparative example. As a result of Nyquist plot of the embodiment, MnO ₂ / GO electrode catalyst as an electrocatalyst Can be added to improve solution resistance and contact resistance characteristics. The 1 kHz resistance value of the embodiment was 0.119 OMEGA, and the comparative example was 0.178 OMEGA, showing a lower resistance value of the embodiment than the comparative example. Also, a semi-circular shape is formed in the high frequency region of the graph, which means that the larger the diameter of the semicircle is, the larger the impedance is. As a result, it can be seen that the diameter of the semicircle of the comparative example is clearly larger than that of the semicircular diameter of the comparative example, whereas the diameter of the semicircular circle of the comparative example is larger than that of the embodiment. That is, when the diameter of the semicircle and the contact resistance are combined, the impedance of the comparative example is higher than that of the embodiment. It is believed that this is due to the high catalytic activity and charge storage characteristics of the electrode catalyst, MnO ₂ / GO.

Example 5: Rate characteristics

In the case of the rate capability of the hybrid capacitor cell, the current density x mA / cm ² (x = 1, 2, 3, 5, 7, 10, 20, 30) The retention ratio (%) was measured. FIG. 3 is a graph showing charge / discharge capacities according to the applied current density. The rate characteristics were measured by applying a range of discharge currents at 1, 3, 5, 7, 10, 20, and 30 mA / cm ² , It can be seen that the embodiment shows better output characteristics. The reason for the increase in the rate characteristics of the embodiment is that the MnO ₂ / GO electrode catalyst is applied as an additive to the electrode to increase the catalytic activity and the charge storage property, and at the same time, the carbon material such as graphene oxide, materials, it is seen that the current - dependent rate characteristics are improved.

Claims (9)

A method of manufacturing an electrode for improving electrochemical characteristics,
Preparing an active material / carbon composite material by mixing an active material and a carbonaceous material, and preparing a manganese oxide / graphene oxide (MnO ₂ / GO) electrode catalyst;
And forming an electrode by mixing the active material / carbon composite and the electrode catalyst. The method according to claim 1,
The active material may be at least one selected from the group consisting of ruthenium oxide (RuO ₂ ), manganese oxide (MnO ₂ ), nickel oxide (Ni (OH) ₂ ), tin oxide (SnO ₂ ), molybdenum oxide (Mo ₂ N), titanium nitride Wherein the electrode is selected from the group consisting of TiN, vanadium oxide (V ₂ O ₅ ), ferrite (MnFe ₂ O ₄ ), tantalum oxide (Ta ₂ O ₅ ) Way. The method according to claim 1,
The carbon material may be activated carbon, graphite, graphene, graphene oxide (GO), reduced graphene oxide (RGO), carbon nano wherein the electrode is selected from the group consisting of carbon fiber, tube, carbon fiber, conducting polymer, aerogel and mixtures thereof. The method according to claim 1,
Wherein the mixing ratio of the active material / carbonaceous material composite to the electrode catalyst material is in a weight ratio of 95: 5. An electrode for improving electrochemical characteristics,
Claims [1]
And an electrode layer comprising an active material / carbonaceous composite laminated on the substrate and a manganese oxide / graphene oxide (MnO ₂ / GO) electrode catalyst. 6. The method of claim 5,
Wherein the active material / carbonaceous composite is an? -Nickel hydroxide / graphen oxide composite (? -Ni (OH) ₂ / GO). 6. The method of claim 5,
The active material may be at least one selected from the group consisting of ruthenium oxide (RuO ₂ ), manganese oxide (MnO ₂ ), nickel oxide (Ni (OH) ₂ ), tin oxide (SnO ₂ ), molybdenum oxide (Mo ₂ N), titanium nitride Wherein the electrode is selected from the group consisting of titanium oxide (TiN), vanadium oxide (V ₂ O ₅ ), ferrite (MnFe ₂ O ₄ ), tantalum oxide (Ta ₂ O ₅ ) and mixtures thereof. 6. The method of claim 5,
The carbon material may be activated carbon, graphite, graphene, graphene oxide (GO), reduced graphene oxide (RGO), carbon nano wherein the electrode is selected from the group consisting of carbon fiber, tube, carbon fiber, conducting polymer, aerogel and mixtures thereof. In an energy storage device,
A cathode comprising an active material / carbon composite and a manganese oxide / graphen oxide (MnO ₂ / GO) electrode catalyst as a cathode active material;
An anode including reduced graphene oxide (RGO) as a negative electrode active material;
And an electrolyte solution in which the anode and the cathode are immersed.

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