KR101643935B1 - Prepatation of materials for energy storage devices using monolithic 3 dimensional of reduced graphene oxide and fabrication method thereby - Google Patents

Abstract

The present invention relates to a method of manufacturing a negative electrode for an energy storage comprising a graphene oxide graphene reduction material, and an energy storage device comprising a negative electrode and a negative electrode produced by the method, wherein the graphene reduction paste and the water- Thereby producing a composite paste; Applying the composite paste to a current collector; And lyophilizing the current collector to form a monolith oxide graphene reduction product. As a result, the composite paste of the oxidized graphene reduced material and the water soluble polymer is lyophilized to form a highly conductive monolithic three-dimensional structure, thereby increasing the regularly arranged active sites of the oxidized graphene reduced material, Cycle cycle and an electrode effect of an energy reservoir with high capacity and high output characteristics.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a negative electrode for an energy storage device including a graphene oxide graphene reduction material having a monolithic three-dimensional structure, and an energy storage device including a negative electrode and a negative electrode, fabrication method thereby}

The present invention relates to a method of manufacturing a negative electrode for an energy storage device including a graphene reduction graphene structure having a monolithic three-dimensional structure, and an energy storage device including a negative electrode and a negative electrode manufactured by the method, and more particularly, And an oxide graphene reduction material formed by lyophilizing a composite paste of a water-soluble polymer to form a monolithic three-dimensional structure, and an energy storage device including the negative electrode and the negative electrode manufactured by the method.

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 need for a lightweight and low power consumption part and a high performance energy storage device capable of realizing a compact and high capacity. In recent years, lithium ion batteries or super capacitors have been used in large-capacity power storage cells such as electric vehicles, battery power storage systems, and small-sized high-performance energy sources such as mobile phones, camcorders, .

 In particular, lithium ion batteries have advantages of high energy density, large capacity per area, low self-discharge rate and long life. In addition, since there is no memory effect, it is convenient for the user to use and has a characteristic that the life is long. However, there is a problem that a low output characteristic and a cycle characteristic are lowered due to reasons such as a long diffusion length of a cathode material and a surface electrolyte interface (SEI) due to a reaction with an electrolyte.

The structure of the lithium ion battery is composed of an anode, a cathode, a separator, and an electrolyte as a current collector. Graphite or metal oxide is used as a general anode material based on a carbon material. This is because it is cheap and has a high energy density. However, in the case of graphite, as shown in FIG. 1, there are a plurality of long graphene layers and the gap between the graphene layers is very short as 3.4 Å, so that ions can not easily enter and exit between the graphene layers. That is, since the ion insertion and desorption time is long, it is difficult to realize high-speed charge / discharge and high output of the battery using it.

In order to solve this problem, a newly proposed carbon-based material is known as a method for manufacturing a hybrid material of metal nano-particles and reduced graphene oxide using hydrogen reduction in the prior art 'Korean Patent Application Publication No. 10-2013-0094560 Oxidation of graphene oxide is used. The oxidized graphene reduction oxidizes the graphene accumulated in a plurality of layers to cause a gap between the layers to spread. Since the graphene oxide graphenes are well dispersed in the solvent, the oxide graphenes present in the solvent are separated one by one using ultrasonic waves or a mixer. Since the graphene oxide layer having the separated layers has an insulating property, the graphene oxide layer is reduced using a reducing agent to finally convert it into a conductive material to finally produce an oxidized graphene reduction material.

Such graphene oxide grains have a nanostructure and thus can produce a wide variety of pores having a large specific surface area and a short diffusion length for easy insertion and desorption of lithium ions and have excellent electric conductivity, There is an advantage that a lithium ion battery capable of this can be manufactured. In addition, since the resistance change due to mechanical deformation is small, a carbon nanomaterial-based cathode capable of applying a flexible energy storage device can be manufactured. However, such nanomaterials suffer from problems of pore formation and deterioration of electrical conductivity when the structure of the cathode structure is formed.

Therefore, it is an object of the present invention to provide a method for forming an open pore capable of contacting an electrolyte by freeze-drying a composite paste of oxidized graphene reduced material and a water-soluble polymer to form an effective three-dimensional structure, A high-speed, high-speed, and high-capacity characteristic, by increasing the active site, increasing the contact surface with the electrolyte, and increasing the electrical conductivity and stability by forming a macro structure that is uniformly arranged vertically. A method for manufacturing a negative electrode for an energy storage comprising a graphene oxide graphene reduction material, and an energy reservoir including a negative electrode and a negative electrode manufactured through the method.

The above object is achieved by a method for producing a composite paste, comprising: mixing a graphene oxide paste and a water-soluble polymer to prepare a composite paste; Applying the composite paste to a current collector; And a step of lyophilizing the current collector to form a monolith oxide graphene reduction material, wherein the graphene graphene graphene graphene reduction graphene reduction material is provided.

Here, the oxidized graphene reduced material paste may include the steps of: synthesizing powdery oxidized graphite flakes from powdery graphite flakes; Dispersing the oxidized graphite flakes in a solvent to form an oxidized graphene dispersion solution; Preparing a cationic graphene oxide graphene dispersion solution through the cation-phi interaction with the graphene oxide dispersion solution; The oxidized graphite flakes are preferably synthesized through an acid treatment, and the acid treatment is carried out by adding acetic acid to the graphite flakes by adding a reducing agent to the graphite flakes Fuming nitric acid, or sulfuric acid.

The reducing agent, sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ₄ OH) hydroxide, sodium borohydride (NaBH _4), hydrazine (N ₂ H _4), dihydro-child ohnik acid (Hydroionic acid), ascorbyl Ascovic acid, and a mixture thereof. The solvent may be selected from the group consisting of acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethylene glycol glycol, polyethylene glycol, tetrahydrofuran, Tetrahydropyran dimethyl formamide, dimethylacetamide, N-methyl-2-pyrrolidone (N Methyl-2-pyrolidone, hexane, cyclohexanone, toluene, chloroform, dichlorobenzene, dimethyl benzene, trimethyl benzene, (Pyridine), Methyl naphthalene, Nitromethane, Acrylonitrile, Octadecylamine, Aniline, Dimethyl sulfoxide, and distilled water. Group and a mixture thereof.

The step of preparing the composite paste may include mixing 50 to 200 parts by weight of the oxidized graphene reduction paste with respect to 100 parts by weight of the water-soluble polymer, and the step of preparing the composite paste may include stirring, ), 3 roll milling, and ball milling are preferably used.

The step of preparing the composite paste further includes the step of adding an adhesive, wherein the adhesive is selected from the group consisting of polyvinylidene fluoride, polyvinylidene chloride, polyvinyl alcohol, But are not limited to, cellulose, carboxymethyl cellulose, hydroxypropylcellulose, polyvinyl pyrrolidone, polyvinylpyrrolidoneepolyvidone, tetrafluoroethylene, polyethylene, polypropylene Polypropylene, and mixtures thereof. The water-soluble polymer may be at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyethyleneimine, polyamideamine, poly Polyvinyl formamide, polyvinyl acetate, polyvinyl acetate, Polyacrylamide, polyvinylpyrrolidone, polydiallyldimethylammonium chloride, polyethylene oxide, polyacrylic acid, polystyrenesulfonic acid, polysilicic acid, Polyphosphoric acid, polyethylenesulfonic acid, poly-3-vinyloxypropane-1-sulfonic acid, poly-4-vinylphenol, 4-vinylphenol, Poly-4-vinylphenyl sulfuric acid, Polyethyleneohosphoric acid, Polymaleic acid, Poly-4-vinylbenzoic acid methyl cellulose, hydroxy ethyl ethyl cellulose, carboxy methyl cellulose, sodium carboxy methyl cellulose, hydroxypropylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, It is preferably one selected from the group consisting of hydroxypropyl cellulose, sodium carboxymethylcellulose, polysaccharide, starch, and mixtures thereof.

The step of applying the composite paste to the current collector may be performed by any one of Template, Patterning, Extruding, Blasting, and Spread, And one kind selected from the group consisting of copper (Cu), aluminum (Al), platinum (Pt), gold (Au), nickel (Ni), titanium (Ti), iron (Fe), molybdenum desirable.

The step of forming the monolith oxide graphene reduction by the above-mentioned freeze-drying is performed at -100 to -270 ° C using liquefied nitrogen, and after the lyophilization to form the monolith oxide graphene reduction, It is preferable that the method further comprises a step of pressing the monolith oxide graphene reduction material, and the pressing step may be performed by any one of pressurization, rolling, and extrusion .

It is preferable that the current collector has a thickness of 1 탆 to 1 cm.

Another object of the present invention is to provide a fuel cell including a current collector; And a cathode active material having a monolithic three-dimensional shape oxidized graphene reduction material formed on one surface of the current collector.

Here, the current collector may be a group consisting of copper (Cu), aluminum (Al), platinum (Pt), gold (Au), nickel (Ni), titanium (Ti), iron (Fe), molybdenum The negative active material further comprises an adhesive, wherein the adhesive is selected from the group consisting of polyvinylidene fluoride, polyvinylidene chloride, polyvinyl alcohol, Carboxymethyl cellulose, Hydroxypropylcellulose, Polyvinyl pyrrolidone, Polyvinylpyrrolidoneepolyvidone, Tetrafluoroethylene, Polyethylene, and the like. , Polypropylene, and a mixture thereof.

Still another object of the present invention is to provide a positive electrode comprising: a positive electrode; And a negative electrode active material having a monolithic three-dimensional shape oxidized graphene reduction product formed on one surface of the current collector, the negative electrode corresponding to the positive electrode; And an isolation film disposed between the anode and the cathode.

According to the structure of the present invention described above, the composite paste of the oxidized graphene reduced material and the water soluble polymer is freeze-dried to form a highly conductive monolith three-dimensional structure, thereby increasing the regularly arranged active sites of the oxidized graphene reduced material High cycle life through stable structure formation, and electrode effect of energy storage device having high capacity and high output characteristics.

1 is an electron micrograph of a reduced graphene oxide particle having an irregular three-dimensional structure by freeze-drying without containing a water-soluble polymer, a negative electrode photograph showing cracking due to an unstable structure when formed on a current collector, The paste is a graphene electron micrograph obtained by drying at 100 DEG C,
FIGS. 2 and 3 are flowcharts of a method of manufacturing a negative electrode for an energy storage device including a graphene reduction graphene of a monolithic three-dimensional structure and a water-soluble polymer according to an embodiment of the present invention,
4 is a perspective view showing a mechanism in which a frozen structure of the composite paste is formed,
5 is a view showing an electron microscope, a transmission electron microscope photograph and a gap between graphenes of the monolithic three-dimensional oxidized graphene reduction material,
Fig. 6 is a graph showing the relationship between the amount of the graphene particles and the amount of the graphene grains of graphite, two-dimensional oxidized graphene reductant film, two-dimensional oxidized graphene reduced film containing water-soluble polymer, Based monolithic three-dimensional oxidized graphene reduction material, Raman spectra,
FIG. 7 is a graph showing a comparison of diffusion distances through X-ray diffraction of a monolithic three-dimensional oxidized graphene reduction product including the comparison group of FIG. 6,
FIG. 8 is an IR spectrum showing the functional groups of the monolithic three-dimensional oxidized graphene reduction including the comparative group of FIG. 6,
FIG. 9 is a DC resistance graph of a monolithic three-dimensional oxide graphene reduction cathode including the comparison group of FIG. 6,
FIGS. 10 to 13 are graphs showing the charge-discharge capacities of graphite, two-dimensional oxidized graphene reduced film, and monolith three-dimensional oxidized graphene reduced material,
FIG. 14 is a graph of Nyquist plot showing the impedance (ac resistance) of the monolithic three-dimensional oxidized graphene reduction using the cells including the comparison group of FIGS. 10 to 13. FIG.

Hereinafter, a method of manufacturing a negative electrode for an energy storage device including a graphene oxide graphene reduction material of a monolith three-dimensional structure according to an embodiment of the present invention will be described in detail with reference to the drawings, and an energy storage device including a negative electrode and a negative electrode do.

A paste is prepared as shown in FIG. 2 (S1).

Here, the paste refers to a paste containing a highly conductive redox graphene oxide.

As a paste manufacturing method, powdery oxidized graphite flakes are synthesized from powdery graphite flakes.

The oxidized graphite flakes are obtained by acid treatment of high purity graphite flakes (99.9995%) in powder form, followed by repeated washing of the aqueous solution and removal of impurities using a centrifuge. Here, the acid treatment may be carried out using any one of the Stoudemämier method, the Hummus method, and the Brody method, and sodium chloride (NaClO ₄ ) or potassium manganate (KMnO ₄ ) is added to fuming nitric acid or sulfuric acid And the mixture is oxidized by stirring at room temperature for 48 hours. Then, neutralization is performed using distilled water, and then filtering and washing are repeated. The oxidized graphite solution is subjected to a drying process and then grinding is used to obtain graphite oxide flakes in powder form.

The oxidized graphite flakes are dispersed and stripped in a solvent to prepare low-defect, high-purity oxide grains. The solvent for dispersing the oxidized graphite flake is the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ₄ H), lithium hydroxide (LiOH), calcium hydroxide (Ca (OH) ₂₎ and mixtures thereof , And the pH of the solvent can be dispersed at a pH of 8 or higher, preferably 10 or higher. In addition, the graphite oxide dispersion and peeling for the formation of the oxidized graphene are formed using at least one of sonication, homogenizer, and high pressure homogenizer. In this case, the time required for dispersion and peeling is 10 minutes to 5 hours. When the time is less than 10 minutes, dispersion and peeling are not smoothly performed. If the treatment is performed for more than 5 hours, defect formation is increased and high quality oxide graphene is obtained I can not.

Next, the cation-high concentration throughout the pie interaction as a method of forming a cationic reaction oxidized graphene dispersion solution, the positive and the pie structure of hexagonal sp ² areas, such as sodium, potassium, ammonium, lithium through the addition of an alkaline solvent, Activate the reaction. These interactions are formed through the removal of the oxygen functional groups of the oxidized graphene through the weak reduction of the alkali solvent and the maintenance of the reaction time for interaction with the cations. In this method, a cationic reaction occurs by maintaining a reaction time of about 1 minute to about 10 hours in an oxidized graphene dispersion solution in the state where no external physical force such as ultrasonic pulverization is applied. When the graphene oxide dispersion solution is prepared by cation-phi interaction, the dispersibility is improved as compared with the conventional dispersion solution. Also, it is preferable to form a highly concentrated dispersion solution of oxidized graphene using a rotary evaporation method in order to activate the cation-phi interaction.

Thereafter, the cationic-reactive oxidative graphene dispersion solution is neutralized with a solvent, and a reducing agent is added to the prepared solution, followed by reduction through a wet process to obtain an oxidized graphene reduction product. The reducing agent may be used a conventional reducing agent, without limitation, such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ₄ OH), hydroxide, sodium borohydride (NaBH _4), hydrazine (N ₂ H ₄ ), Hydroionic acid, ascorbic acid, and a mixture thereof.

The solvent may be selected from the group consisting of acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethylene glycol glycol, polyethylene glycol, tetrahydrofuran, Tetrahydropyran dimethyl formamide, dimethylacetamide, N-methyl-2-pyrrolidone (N Methyl-2-pyrolidone, hexane, cyclohexanone, toluene, chloroform, dichlorobenzene, dimethyl benzene, trimethyl benzene, (Pyridine), Methyl naphthalene, Nitromethane, Acrylonitrile, Octadecylamine, Aniline, Dimethyl sulfoxide, and distilled water. Group and a mixture thereof.

The paste is mixed with a water-soluble polymer to prepare a dispersed composite paste (S2).

The paste containing the high-concentration and high-conductivity oxide graphene reductions prepared in the step S1 is mixed with a water-soluble polymer to prepare a dispersed composite paste which is stably dispersed. The oxidized graphene reduction product dispersed in the dispersion solution is made into a paste through centrifugation, and the water-soluble polymer is mixed with this to disperse the oxidized graphene reduction product to prepare a dispersed composite paste. The oxidized graphene reduction paste is preferably mixed in an amount of 50 to 200 parts by weight based on 100 parts by weight of the water-soluble polymer. If the dispersed composite paste is less than 50 parts by weight, the required amount of graphene is small and is not suitable for a battery. If the dispersed composite paste is more than 200 parts by weight, the amount of the water soluble polymer is small.

The water-soluble polymer may be at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyethyleneimine, polyamideamine, polyvinyl formamide, polyvinyl acetate, poly Polyacrylamide, polyvinylpyrrolidone, polydiallyldimethylammonium chloride, polyethylene oxide, polyacrylic acid, polystyrenesulfonic acid, polysilicic acid, Polyphosphoric acid, polyethylenesulfonic acid, poly-3-vinyloxypropane-1-sulfonic acid, poly-4-vinylphenol, 4-vinylphenol, poly-4-vinylphenyl sulfuric acid, polyethylenenaphosphoric acid, polymaleic acid, poly-4- Poly-4-vinylbenzoic acid, methyl cellulose, hydroxy ethyl ethyl cellulose, carboxy methyl cellulose, sodium carboxy methyl cellulose, hydroxy- It is preferably one selected from the group consisting of hydroxypropyl cellulose, sodium carboxymethylcellulose, polysaccharide, starch and mixtures thereof.

The slurry is prepared using at least one of the following methods: Stirring, Thinky mixer, 3 roll milling and Ball milling for smooth dispersion of the oxidized graphene paste and the water-soluble polymer .

In order to improve the adhesion between the composite paste and a current collector to be described later, an adhesive may be added to the composite paste as the case may be. The adhesive is generally used to apply an active material on a metal such as polyvinylidene fluoride, polyvinylidene chloride, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, A group consisting of cellulose, hydroxypropylcellulose, polyvinyl pyrrolidone, polyvinylpyrrolidoneepolyvidone, tetrafluoroethylene, polyethylene, polypropylene, and mixtures thereof Lt; / RTI > group.

The composite paste is applied to the current collector (S3).

The composite paste 10 including the oxidized graphene reduction product and the water-soluble polymer prepared through the step S2 is applied to the current collector 20 for producing the negative electrode of the energy storage device. The frame 30 for isolating the necessary area from the outside as shown in FIG. 3A is placed on the top of the current collector 20 and the composite paste 10 is injected into the frame 30. Thereafter, the paste 10 is uniformly applied to the upper portion of the paste 10 through the rolling bar 40 as shown in FIG. Here, the current collector 20 is formed of a group consisting of copper (Cu), aluminum (Al), platinum (Pt), gold (Au), nickel (Ni), titanium (Ti), iron (Fe), molybdenum And one kind selected from the mixture group thereof is preferable.

The composite paste 10 may be applied to the current collector 20 by using a processing method such as patterning, extruding, blasting, spreading, etc., without using a frame.

The composite paste is freeze-dried to form a graphene oxide graphene reduction material (S4).

The composite paste 10 disposed on the upper portion of the current collector 20 is lyophilized to have a graphene reduction graphene 50 having a monolithic three-dimensional structure as shown in Fig. 3C. Freeze-drying is performed using liquefied nitrogen at -100 to 270 ° C for 10 to 60 minutes, and then it is dried at 10 ^-3 torr for 1 hour to 24 hours.

When the composite paste 10 is freeze-dried, phase separation occurs between the water-soluble polymer 11 and the water 60 because the water 60 having a low freezing point is first frozen as shown in FIG. That is, when the water 60 is frozen in the form of a column, the oxidized graphene reduction product 13 and the water-soluble polymer 11 are aligned in a region where the water 13 is not frozen, When it becomes lower than the temperature, it is frozen. And then dried at a low temperature, the water 13 and the water-soluble polymer 11 are sublimated to form a graphene reduction graft 50 having a monolithic three-dimensional structure similar to the pine shape as shown in FIG. Such a monolithic three-dimensional structure is generated by the freezing point difference with the composite paste 10 excluding the water 11 and the water 11.

The collector preferably has a thickness of 1 탆 to 1 cm.

The graphene oxide grains are squeezed (S5)

The oxidized graphene reduction material 50 having the monolithic three-dimensional structure formed by freeze-drying forms a large active area by sublimation of the water 13 and the water-soluble polymer 11, The volume of the reduced material 50 becomes larger than the reduced material of the graphene oxide by freeze drying. When the volume of the monolithic oxidized graphene reduction material 50 is large, the total volume of the battery becomes large, so that it is pressed to the current collector 20 to reduce the volume. As a method of pressing the mold 30, the mold 30 installed in the step S3 is removed from the current collector 20, and the monolith oxide graphene reduction material 50 is squeezed using a generally used compression method. The pressing method includes pressing the upper portion of the monolith oxide graphene reduction material 50 using a heavy object or a gas, rolling the material through a plurality of rolls, passing through a long pipe, Extrusion or the like may be used. The cathode 100 in which the graphene reduction material 50 having a monolithic three-dimensional structure is formed on the current collector 20 as described above can be used for an energy storage device.

A stacked energy storage device is fabricated using a cathode (S6).

A stacked energy storage device such as a lithium ion battery or a supercapacitor is manufactured using the cathode 100 including the monolithic three-dimensional shaped oxidized graphene reduction 50 manufactured through steps S1 to S5. Here, the energy reservoir is preferably a pouch shape or a coin cell shape. In the case of a lithium ion battery, a separator (300) is provided between the cathode (100) and the anode (200) made of lithium metal to finally manufacture a battery.

In the case of the graphite or graphene compound used as a conventional negative electrode active material, a plurality of graphenes are stacked very close to each other and the active site is narrow, so that it is difficult to insert and desorb ions, There was a problem.

However, since the graphene oxide grains having a monolithic three-dimensional structure produced through steps S1 to S5 have a wide active site, it is possible to perform ion implantation and desorption in a short period of time, And the charge / discharge capacity is large.

Hereinafter, embodiments and comparative examples of the present invention will be described in detail with reference to the drawings.

In the drawings, graphs of analytical graphs of graphene oxide grains having a monolithic three-dimensional structure as an embodiment and graphs of various experimental results using graphene graphene reductions as a comparative example are shown.

6A shows Raman spectra. Here, graphite (NG), oxidized graphene reduction (2D-rGO) dried on a hot plate by a general method, oxidized graphene reduced material and water soluble polymer by a general method, (2-rGO (SCMC)), oxidized graphene reduction (rGO foam) prepared by freeze-drying, and water-soluble polymer are mixed and lyophilized to obtain a graphene oxide reduced graft having a monolith structure (M- rGO (SCMC)).

It can be seen that the peak of the A region appears as a graphite peak in all the samples. The peak of the B region is the defect peak or the peak of the SCMC, and if the defect peak, the peak of the C region is reduced. The 2D-rGO (SCMC) and M-rGO (SCMC) peaks of the C-region are recognized as the peaks of the A region and the 2D-rGO foam peak, It can be confirmed that the peak of the A region is the SCMC peak.

Fig. 6B also relates to Raman spectra, wherein the respective I _D / I _G ratios were: 2D-rGO: 1.23, 2D-rGO (SCMC): 1.84, rGO foam: 1.34, M-rGO (SCMC) that was the highest, I _2D / _G ratio of D-rGO: 0.42, 2D- rGO (SCMC): 0.89, rGO foam: 0.21, M-rGO (SCMC): also M-rGO (SCMC) 1.10 Is the highest. Therefore, it is confirmed that the quality of M-rGO (SCMC) is the best.

FIG. 7 shows X-ray diffraction, which shows the theta in each peak, the interlayer spacing through the position of the peak, the diffusion distance through the crystallization spacing Lc through the half width of the peak DGC: 15: 2, rGO: 15: 2, rGO: 15, rGO: graphite: 437.2, 2D-rGO: 15.3, 14.7, and M-rGO (SCMC): 13.8, indicating that the oxidized graphene reduction having a monolithic three-dimensional structure has the lowest diffusion distance. It can be confirmed that it is the structure that facilitates insertion and desorption of ions through this.

Figure 8 shows the IR spectrum, where C = C sp ² peak means graphite peak. Two peaks representing CO stretching can be found at the CO stretching position because graphene oxidizes with oxygen functional groups around graphene. In the case of GO, which indicates graphene oxide, a peak is found at this position, but rGO can not find a CO stretching peak because there is no oxygen functional group in the oxidized graphene reduction. In addition, the peak of rGO (SCMC) is similar to the lower SCMC peak, and it can be confirmed that the oxidized graphene reduction and the water-soluble polymer are mixed.

9 is a graph showing the series resistance of an electrode including each sample. The larger the slope, the lower the resistance. The slope of 2D-rGO is the highest, while the resistance of 2D-rGO is the lowest. Since 2D-rGO has a small active area, it is not suitable for electrode because of its small storage capacity. Next, M-rGO (SCMC) and 2D-rGO (SCMC) have a small resistance. 2D-rGO (SCMC) is not suitable for electrodes for the same reason as 2D-rGO. In comparison with the freeze-dried M-rGO (SCMC) and rGO foam, the resistance of M-rGO (SCMC) is low because it has a uniformly arranged monolith structure pore Is considered to be an important factor in lowering resistance.

Fig. 10 shows the capacity when the battery including M-rGO (SCMC) was rapidly charged and discharged. Fig. 10C shows the capacity when charging and discharging for 1 hour, 0.2C for 2 hours, 10C for 1/10 hour, Represents 1/50 hour. CHA represents charge and DCH represents discharge. As can be seen from the graph, it is confirmed that even if rapid charge / discharge is performed in a short time of 1/50 hour, the capacity is large.

FIG. 11 is a graph showing the capacity when the cells including 2D-rGO and M-rGO (SCMC) are charged and discharged at 0.2C, that is, for 5 hours. It can be seen that the charge-discharge capacity of M-rGO (SCMC) is much higher than that of 2D-rGO.

FIG. 12 is a graph for confirming whether a rapid discharge is possible when the cell is discharged for each time, and it was tested for each cell including NG and M-rGO (SCMC). Here, 0.2C is 5 hours, 1C is 1 hour, 5C is 1/5 hour, 10C is 1/10 hour, 30C is 1/30 hour, 50C is 1/50 hour, and 100C is 1/100 hour . As a result of repeating the charge / discharge cycle five times for each time, M-rGO (SCMC) can discharge even at a time of 1/100, but it can be confirmed that NG has a very small discharge capacity. Especially, no discharge occurred at 1/50 and 1/100 hours.

FIG. 13 shows how stable the charging / discharging of the battery is by turning the charging / discharging cycle 100 times. It can be confirmed that M-rGO (SCMC) is stable even after 100 cycles. However, if NG exceeds 90, It can be confirmed that the discharge capacity is reduced.

FIG. 14 is a graph showing impedance measured using cells including NG, 2D-rGO, and M-rGO (SCMC), an electrolyte, and a separator. The electrode resistance, the electrolyte resistance, It is the Nyquist plot graph that can be checked together. This graph shows that the larger the slope, the smaller the diffusion resistance of the ions. Therefore, M-rGO (SCMC) and NG with high slope have low resistance. It is also possible to draw a semicircle in the higher frequency range, the larger the diameter of the semicircle being drawn, the larger the impedance. The diameter of the circle is the largest, and M-rGO (SCMC) is the smallest. Therefore, when combined as a whole, it can be confirmed that M-rGO (SCMC) has the smallest impedance.

As a result of examining the above embodiments and comparative examples, the M-rGO (SCMC) of the present invention, when compared with the NG, 2D-rGO and r-GO foam used as comparative examples, However, M-rGO (SCMC) was found to have the smallest impedance when the resistance was measured using a cell. This means that the comparison example is not suitable for the cell because the active site is small. Also, as a result of the rapid charge-discharge experiment of the embodiment, it was confirmed that the charge-discharge capacity was large and rapid charge-discharge was possible in a short time. It has been confirmed that graphene oxide grains having a monolithic three-dimensional structure are very suitable materials for energy storage devices.

10: composite paste 11: water-soluble polymer
13: water 15: oxalate graphene reduction
20: House Whole 30: Frame
40: Rolling bar 50: Monolith oxide graphene reduction
100: cathode 200: anode
300: membrane

Claims (19)

A method of manufacturing a negative electrode for an energy storage comprising a graphene reduction oxide having a monolithic three-dimensional structure,
Mixing the oxidized graphene reduction paste and the water-soluble polymer to prepare a composite paste;
Applying the composite paste to a current collector;
And a step of lyophilizing the current collector to form a monolith oxide graphene reduction product, wherein the graphene oxide graphene reduction product has a monolithic three-dimensional structure. The method according to claim 1,
The oxidized graphene reduction paste is prepared by mixing,
Synthesizing powdery oxidized graphite flakes from the powdered graphite flakes;
Dispersing the oxidized graphite flakes in a solvent to form an oxidized graphene dispersion solution;
Preparing a cationic graphene oxide graphene dispersion solution through the cation-phi interaction with the graphene oxide dispersion solution;
Wherein the graphene oxide graphene reduction solution is prepared by reducing the graphene oxide graphene dispersion solution using a reducing agent. 3. The method of claim 2,
Wherein the oxidized graphite flakes are synthesized by acid treatment of the graphite flakes. 2. The method of claim 1, wherein the graphite flakes are synthesized through acid treatment. The method of claim 3,
Wherein the acid treatment is performed by using fuming nitric acid or sulfuric acid in the graphite flake. 2. The method of claim 1, wherein the graphite flake is treated with fuming nitric acid or sulfuric acid. 3. The method of claim 2,
The reducing agent,
Sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ₄ OH), hydroxide, sodium borohydride (NaBH _4), hydrazine (N ₂ H _4), dihydro-child ohnik acid (Hydroionic acid), ascorbyl biksan (Ascovic acid ), And a mixture thereof. The solvent may be selected from the group consisting of acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethylene glycol glycol, polyethylene glycol, tetrahydrofuran, Tetrahydropyran dimethyl formamide, dimethylacetamide, N-methyl-2-pyrrolidone (N Methyl-2-pyrolidone, hexane, cyclohexanone, toluene, chloroform, dichlorobenzene, dimethyl benzene, trimethyl benzene, (Pyridine), Methyl naphthalene, Nitromethane, Acrylonitrile, Octadecylamine, Aniline, Dimethyl sulfoxide, and distilled water. And a graphene oxide grains having a monolithic three-dimensional structure, wherein the graphene grains have a graphene reduction structure. The method according to claim 1,
The step of preparing the composite paste includes:
Wherein the oxidized graphene reduction paste is mixed with 50 to 200 parts by weight of the oxidized graphene reduction paste to 100 parts by weight of the water-soluble polymer. The method according to claim 1,
The step of producing the composite paste includes:
Wherein the method comprises using graphene oxide grains having a monolithic three-dimensional structure, characterized in that at least one of the following methods is used: Stirring, Mixing (Thinky mixer), 3 roll milling, Ball milling Method of manufacturing negative electrode for energy storage device. The method according to claim 1,
The step of producing the composite paste includes:
Further comprising the step of adding an adhesive,
Polyvinylidene fluoride, polyvinylidene chloride, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropylcellulose, polyvinyl pyrrolidone (polyvinylpyrrolidone), polyvinylpyrrolidone Wherein the monolithic three-dimensional structure is one selected from the group consisting of polyvinylpyrrolidone, polyvinylpyrrolidone, polyvinylpyrrolidoneepolyvidone, tetrafluoroethylene, polyethylene, polypropylene, and mixtures thereof. Of the oxide graphene. The method according to claim 1,
The water-
Examples thereof include polyvinyl alcohol, polyethylene glycol, polyethyleneimine, polyamideamine, polyvinyl formamide, polyvinyl acetate, polyacrylamide, and the like. ), Polyvinylpyrrolidone, polydiallyldimethylammonium chloride, polyethylene oxide, polyacrylic acid, polystyrenesulfonic acid, polysilicic acid, polyphosphoric acid, poly-3-vinyloxypropane-1-sulfonic acid, poly-4-vinylphenol, and the like. Poly-4-vinylphenylsulfonic acid, polyethylenenaphosphoric acid, polymaleic acid, poly-4-vinylbenzoic acid, c acid, methyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, sodium carboxy methyl cellulose, hydroxy propyl cellulose, hydroxypropyl cellulose, , Sodium carboxymethylcellulose, polysaccharide, starch, and mixtures thereof. The graphene three-dimensional structure oxidized graphene-reduced energy is one kind selected from the group consisting of sodium carboxymethylcellulose, polysaccharide, starch, A method for manufacturing a negative electrode for a storage device. The method according to claim 1,
The step of applying the composite paste to the current collector includes:
Wherein the energy storage comprises graphene oxide graphene grains having a monolithic three-dimensional structure, characterized by using any one of a template, patterning, extruding, blasting, and spreading. (Method for manufacturing negative electrode). The method according to claim 1,
The collector may be formed of a group consisting of copper (Cu), aluminum (Al), platinum (Pt), gold (Au), nickel (Ni), titanium (Ti), iron (Fe), molybdenum And the graphene oxide grapnewine having a monolithic three-dimensional structure. The method according to claim 1,
The step of lyophilization to form monolith oxide graphene reduction comprises:
Wherein the graphene reduction grapnem is formed at a temperature of -100 to -270 ° C using liquefied nitrogen. The method according to claim 1,
After the lyophilization to form the monolith oxide graphene reductant,
Further comprising the step of compressing the monolith oxide graphene reduction material to form a graphene oxide graphene graphene graphene graphene graphene graphene graphene graphene graphene grains. 14. The method of claim 13,
Wherein the pressing step comprises:
A method for manufacturing an anode for an energy storage comprising a graphene oxide graphene reduction material having a monolithic three-dimensional structure, characterized by using any one of pressurization, rolling, and extrusion. The method according to claim 1,
Wherein the current collector has a thickness of 1 to 1 cm. ≪ RTI ID = 0.0 > 11. < / RTI > delete delete delete delete

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