KR20190047490A - Asymmetric super capacitor and method of fabricating of the same - Google Patents

Abstract

A supercapacitor is provided. The supercapacitor comprises: a first electrode fiber including a reduced graphene oxide and a first carbon nanotube twisted to surround the reduced graphene oxide; a second electrode fiber including a manganese dioxide and a second carbon nanotube twisted to surround the manganese dioxide; and an electrolyte between the first and second electrode fibers.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to asymmetric super capacitors,

The present invention relates to an asymmetric supercapacitor and a method of manufacturing the same, and more particularly, to an asymmetric supercapacitor including a first electrode including reduced graphene oxide, a second electrode including manganese dioxide, and an electrolyte, ≪ / RTI >

Supercapacitor has high energy and power performance and is one of the most popular energy storage media of the future with high performance battery. Conventionally, energy storage devices such as batteries and supercapacitors are heavy and have a disadvantage that they are limited in various applications because of lack of mechanical freedom.

In particular, a supercapacitor having a symmetric electrode structure using the same kind of active material of the anode and the cathode and having a solid-based electrolyte has a limitation that the operating voltage range is about 1 V or so. In addition, a super-capacitor having a core-shell structure that simply coats an active material on the surface of the conductive fiber is disadvantageous in that the loading of the active material is limited to the surface of the fiber and the actual loading amount is small. And the diffusion of electrons is lowered, and the possibility of a drop in performance is great.

In order to overcome these disadvantages, many research and development on super capacitors are under way. For example, Korean Patent Laid-Open Publication No. 10-2013-0006957 (Application No. 10-2011-0062576, Applicant: Korean Ceramic Technology Institute) provides a passage in which an average interlayer distance is in the range of 3.385 to 0.445 nm and electrolyte ions are introduced or discharged Wherein the porous activated carbon is used as an electrode active material for the positive electrode and the negative electrode and a separation membrane for preventing the short-circuit between the positive electrode and the negative electrode is disposed between the positive electrode and the negative electrode, Wherein the anode, the separator, and the cathode are impregnated with an electrolytic solution, and the electrolytic solution is an aqueous electrolytic solution, and a method of manufacturing the same.

Korean Patent Publication No. 10-2013-0006957

SUMMARY OF THE INVENTION It is an object of the present invention to provide an asymmetric supercapacitor with improved operating voltage and a method of manufacturing the same.

It is another object of the present invention to provide an asymmetric supercapacitor with improved storage capacity and a method of manufacturing the same.

Another aspect of the present invention is to provide a highly elastic asymmetric supercapacitor and a method of manufacturing the same.

Another aspect of the present invention is to provide an asymmetric supercapacitor having a simplified manufacturing process and a manufacturing method thereof.

The technical problem to be solved by the present invention is not limited to the above.

According to an aspect of the present invention, there is provided a supercapacitor.

According to one embodiment, the supercapacitor comprises a first electrode fiber comprising a reduced graphene oxide and a first carbon nanotube sheet twisted to surround the reduced graphene oxide, a manganese dioxide, and a second manganese dioxide A second electrode fiber including a twisted second carbon nanotube sheet, and an electrolyte between the first electrode fiber and the second electrode fiber.

According to one embodiment, the supercapacitor may comprise a wt% of the reduced graphene oxide in the first electrode fiber is higher than a wt% of the manganese dioxide in the second electrode fiber.

According to an embodiment, the number of the first carbon nanotube sheets in the first electrode fibers may be greater than the number of the second carbon nanotube sheets in the second electrode fibers.

According to one embodiment, the reduced graphene oxide may comprise nitrogen doped.

According to one embodiment, the first and second carbon nanotube sheets are provided in a rolled stacked form, and between the first and second carbon nanotube sheets that are laminated and dried, The graphene oxide, and the manganese dioxide, respectively.

According to an embodiment, the first and second electrode fibers extend in a first direction and are cut in a first plane having a normal line in the first direction, The cross section may include that provided in a spiral.

According to one embodiment, the supercapacitor is characterized in that in the first electrode fiber, the wt% of the reduced graphene oxide is higher than the wt% of the first carbon nanotube sheet, and in the second electrode fiber, Of the second carbon nanotube sheet is greater than the wt% of the second carbon nanotube sheet.

In order to solve the above-described technical problems, the present invention provides a method of manufacturing a supercapacitor.

According to one embodiment, a method of fabricating a supercapacitor includes the steps of preparing a first carbon nanotube sheet, providing reduced graphene oxide on the first carbon nanotube sheet, Preparing a first carbon fiber sheet by twisting the first carbon nanotube sheet provided with an oxide; preparing a second carbon nanotube sheet; providing manganese dioxide on the second carbon nanotube sheet; Twisting the second carbon nanotube sheet provided with manganese dioxide to produce a second electrode fiber, and coating the first and second electrode fibers with an electrolyte.

According to one embodiment, the step of providing the reduced graphene oxide to the first carbon nanotube sheet and the step of providing the manganese dioxide to the second carbon nanotube sheet include those performed in a solution process .

According to one embodiment, the step of providing the reduced graphene oxide to the first carbon nanotube sheet comprises the steps of preparing a first source solution in which the reduced graphene oxide is dispersed, Wherein the step of providing the manganese dioxide to the second carbon nanotube sheet comprises the steps of preparing a second source solution in which the manganese dioxide is dispersed, 2 source solution on the second carbon nanotube sheet, wherein the wt% of the reduced graphene oxide in the first source solution is higher than the wt% of the manganese dioxide in the second source solution ≪ / RTI >

According to an embodiment, the step of providing the reduced graphene oxide to the first carbon nanotube sheet may include providing a first source solution in which the reduced graphene oxide is dispersed on the first carbon nanotube sheet And drying the first carbon nanotube sheet provided with the first source solution repeatedly a plurality of times.

A supercapacitor according to an embodiment of the present invention includes a first electrode fiber including a reduced carbon nanotube sheet and a first carbon fiber sheet twined so as to surround the reduced graphene oxide and the reduced graphene oxide and a second electrode fiber including manganese dioxide and a twisted material to surround the manganese dioxide 2 < / RTI > carbon nanotube sheet. Accordingly, a highly efficient asymmetric supercapacitor including the reduced graphene oxide and the manganese dioxide can be provided.

In addition, the supercapacitor may further include, before producing the fiber using the first and second carbon nanotube sheets, the reduced graphene oxide and the manganese dioxide on the first and second carbon nanotube sheets And the first and second carbon nanotube sheets are twisted with the reduced graphene oxide and the manganese dioxide provided, whereby the first and second electrode fibers can be produced. Accordingly, the content of the reduced graphene oxide and the manganese dioxide in the first and second electrode fibers can be increased, and the energy storage amount of the supercapacitor can be improved.

FIGS. 1 and 2 are views for explaining a manufacturing process of a first electrode fiber included in a supercapacitor according to an embodiment of the present invention.
FIGS. 3 and 4 are views for explaining a manufacturing process of a second electrode fiber included in a supercapacitor according to an embodiment of the present invention.
5 is a view for explaining a supercapacitor according to an embodiment of the present invention and a method of manufacturing the same.
6 is a photograph of the first electrode fiber included in the supercapacitor according to the first embodiment of the present invention.
7 is a photograph of the second electrode fiber included in the supercapacitor according to the second embodiment of the present invention.
8 is a graph showing electrochemical characteristics of a supercapacitor according to Comparative Example 1 of the present invention.
9 is a graph comparing characteristics of the first electrode fibers according to the content of reduced graphene oxide according to an embodiment of the present invention.
10 is a graph comparing the characteristics of the first electrode fiber and the second electrode fiber according to the embodiments of the present invention.
11 is a graph showing characteristics of a supercapacitor according to a third embodiment of the present invention.
12 is a graph showing the characteristics of the supercapacitor according to the fourth embodiment of the present invention.
13 is a graph comparing characteristics of supercapacitors according to embodiments of the present invention.
14 is a graph comparing energy storage characteristics of supercapacitors according to embodiments of the present invention and comparative examples.
15 is a graph showing electrochemical characteristics of a first electrode, a second electrode, and a supercapacitor according to embodiments of the present invention.
16 is a graph showing electrochemical characteristics of supercapacitors according to embodiments of the present invention.
17 is a graph comparing characteristics of supercapacitors according to the embodiment of the present invention and the comparative example.
FIG. 18 is a graph showing charge / discharge characteristics of a supercapacitor according to the third embodiment of the present invention. FIG.
FIG. 19 is a photograph of the operation of an electrode fabric and a circuit using the electrode fabric according to the fifth embodiment of the present invention. FIG.
20 is a graph showing electrochemical characteristics when the electrode fabrics according to the fifth embodiment of the present invention are connected in series and in parallel.
FIG. 21 is a graph comparing characteristics of the electrode fabric according to the fifth embodiment of the present invention in a case where the electrode cloth is connected in series and a case where the electrode cloth is connected in parallel. FIG.
22 is a graph showing the durability of the electrode fabric according to the fifth embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when an element is referred to as being on another element, it may be directly formed on another element, or a third element may be interposed therebetween. Further, in the drawings, the thicknesses of the films and regions are exaggerated for an effective explanation of the technical content.

Also, while the terms first, second, third, etc. in the various embodiments of the present disclosure are used to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. Thus, what is referred to as a first component in any one embodiment may be referred to as a second component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Also, in this specification, 'and / or' are used to include at least one of the front and rear components.

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises " or " having " are intended to specify the presence of stated features, integers, Should not be understood to exclude the presence or addition of one or more other elements, elements, or combinations thereof. Also, in this specification, the term " connection " is used to include both indirectly connecting and directly connecting a plurality of components.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIGS. 1 and 2 are views for explaining a manufacturing process of a first electrode fiber included in a supercapacitor according to an embodiment of the present invention.

Referring to FIG. 1, a first carbon nanotube sheet 110 may be prepared. According to an embodiment of the present invention, the step of preparing the first carbon nanotube sheet includes the steps of: preparing a carbon nanotube forest by chemical vapor deposition; 110). ≪ / RTI >

According to one embodiment, the first carbon nanotube sheet 110 may include a plurality of carbon nanotubes extending in a first direction. Also, according to one embodiment, the plurality of carbon nanotubes may be multi-wall carbon nanotubes (MWCNTs).

According to one embodiment, the first carbon nanotube sheet 110 may be prepared on the support substrate 100. For example, the supporting substrate 100 may be a glass substrate. Alternatively, for example, the supporting substrate 100 may include a plastic substrate, a semiconductor substrate, a ceramic substrate, or a metal substrate.

A reduced graphene oxide 120 may be provided on the first carbon nanotube sheet 110. The reduced graphene oxide 120 may have lower conductivity than the first carbon nanotube sheet 110 and may have a higher charge storage capacity than the first carbon nanotube sheet 110.

The step of providing the reduced graphene oxide 120 on the first carbon nanotube sheet 110 may include preparing a first source solution in which the reduced graphene oxide 120 is dispersed, 1 source solution on the first carbon nanotube sheet 110 and drying the first carbon nanotube sheet 110 provided with the first source solution.

According to one embodiment, the first source solution may be prepared by introducing the reduced graphene oxide 120 into a solvent and subjecting the reduced graphene oxide 120 to ultrasonic treatment to disperse the reduced graphene oxide 120. For example, the solvent may be dimethylformamide. For example, the wt% of the reduced graphene oxide 120 in the first source solution may be provided at 8 mg / ml. Also, according to one embodiment, the first source solution may be provided on the first carbon nanotube sheet 110 by a drop casting method.

According to one embodiment, there is provided a method of fabricating a carbon nanotube sheet, comprising: providing a first source solution in which the reduced graphene oxide (120) is dispersed, on the first carbon nanotube sheet (110) The step of drying the carbon nanotube sheet 110 may be repeatedly performed. Accordingly, the content of the reduced graphene oxide 120 on the first carbon nanotube sheet 110 can be increased.

According to one embodiment, the reduced graphene oxide 120 may be provided in the form of a flake. According to one embodiment, the size of the reduced graphene oxide 120 in the first source solution may be substantially the same as each other. Alternatively, according to another embodiment, the size of the reduced graphene oxide 120 in the first source solution may be different.

Referring to FIG. 2, the first electrode fiber 130 may be manufactured by twisting the first carbon nanotube sheet 110 provided with the reduced graphene oxide 120. According to one embodiment, the step of fabricating the first electrode fibers 130 may include the step of using the first direction in which the plurality of carbon nanotubes extend as a rotation axis to twist one end of the plurality of carbon nanotubes (twist). For example, the first carbon nanotube sheet 110 provided with the reduced graphene oxide 120 may have about 3000 turns per meter.

Accordingly, an inner region of the first electrode fiber 130 may be provided in the form of a rolled stacked structure of the first carbon nanotube sheet 110. The reduced graphene oxide 120 may be provided between the dried and stacked first carbon nanotube sheets 110. In other words, in a case where a first plane having a normal line in the first direction in which the first electrode fibers 130 extend is defined, in the cross section of the first electrode fibers 130 cut into the first plane, The cross section of the first carbon nanotube sheet 110 may be provided spirally and the reduced graphene oxide 120 may be provided between the spiral first carbon nanotube sheets 110.

According to one embodiment, in the first electrode fiber 130, the wt% of the reduced graphene oxide 120 may be higher than the wt% of the first carbon nanotube sheet 110. In other words, the first electrode fibers 130 may include more reduced graphene oxide 120 than the first carbon nanotube sheet 110. Accordingly, the first electrode fibers 130 can have improved charge storage characteristics.

According to one embodiment, the reduced graphene oxide 120 may be doped with nitrogen. In other words, the first electrode fibers 130 may be formed in a form in which the reduced graphene oxide doped with nitrogen is sandwiched between the first and the first carbon nanotube sheets 110 that are dried and laminated. In contrast, when the reduced graphene oxide 120 is doped with a metal other than nitrogen, the electrochemical reaction may be unstable, thereby deteriorating the characteristics of the supercapacitor.

FIGS. 3 and 4 are views for explaining a manufacturing process of a second electrode fiber included in a supercapacitor according to an embodiment of the present invention.

Referring to FIG. 3, a second carbon nanotube sheet 210 may be prepared. According to one embodiment, the second carbon nanotube sheet 210 may be prepared in the same manner as the preparation method of the first carbon nanotube sheet 110 described with reference to FIG.

Manganese dioxide (MnO ₂ , 220) may be provided on the second carbon nanotube sheet 210. The manganese dioxide 220 may have lower conductivity than the second carbon nanotube sheet 210 and may have a higher charge storage capacity than the second carbon nanotube sheet 210.

The step of providing the manganese dioxide 220 on the second carbon nanotube sheet 210 may include preparing a second source solution in which the manganese dioxide 220 is dispersed, On a carbon nanotube sheet (210).

According to one embodiment, the second source solution may be prepared by introducing the manganese dioxide (220) into a solvent and subjecting the manganese dioxide (220) to ultrasonic treatment to disperse the manganese dioxide (220). For example, the solvent may be ethanol. For example, the wt% of manganese dioxide 220 in the second source solution may be provided at 5 mg / ml. Also, according to one embodiment, the second source solution may be provided on the second carbon nanotube sheet 210 by a drop casting method.

According to one embodiment, the manganese dioxide 220 may be provided in the form of particles. According to one embodiment, the sizes of the manganese dioxide (220) in the second source solution may be substantially equal to each other. Alternatively, according to another embodiment, the size of the manganese dioxide 220 in the second source solution may be different.

Referring to FIG. 4, the second electrode fiber 230 may be manufactured by twisting the second carbon nanotube sheet 210 provided with the manganese dioxide 220. According to one embodiment, the step of fabricating the second electrode fibers 230 may include the step of using the first direction in which the plurality of carbon nanotubes extend as a rotation axis to twist one end of the plurality of carbon nanotubes (twist). According to one embodiment, the number of twists per meter of the second carbon nanotube sheet 210 may be larger than the number of twists per meter of the first carbon nanotube sheet 110. For example, the second carbon nanotube sheet 210 provided with the manganese dioxide 220 may have a number of twists per meter of about 5000 times.

Accordingly, an inner region of the second electrode fiber 230 may be provided in a rolled stacked form of the second carbon nanotube sheet 210. The manganese dioxide (220) may be provided between the second carbon nanotube sheet (210) and the dried carbon nanotube sheet (210). In other words, in a case where a first plane having the normal direction of the first direction in which the second electrode fibers 230 extend is defined, in the cross section of the second electrode fibers 230 cut into the first plane, The cross section of the second carbon nanotube sheet 210 may be provided spirally and the manganese dioxide 220 may be provided between the spiral second carbon nanotube sheet 210.

According to one embodiment, in the second electrode fiber 230, the wt% of the manganese dioxide 220 may be higher than the wt% of the second carbon nanotube sheet 210. In other words, the second electrode fibers 230 may include the manganese dioxide 220 more than the second carbon nanotube sheet 210. Accordingly, the second electrode fibers 230 can have improved charge storage characteristics.

Hereinafter, a supercapacitor including the first electrode fiber 130 and the second electrode fiber 230 described above and a manufacturing method thereof will be described with reference to FIG.

5 is a view for explaining a supercapacitor according to an embodiment of the present invention and a method of manufacturing the same.

Referring to FIG. 5A, the first electrode fiber 130 and the second electrode fiber 230 described with reference to FIGS. 1 to 4 are prepared. The first electrode fiber 130 and the second electrode fiber 230 may be coated with an electrolyte 300, respectively. It may be, for example, the electrolyte 300 includes a PVA (polyvinyl alcohol) -LiCl or PVDF-HFP (polyvinylidenefluoride-hexafluoropropylene) -TEABF 4 (tetraethylammoniumtetrafluouroborate).

5 (b), the first electrode fiber 130 coated with the electrolyte 300 and the second electrode fiber 230 are twisted to form the supercapacitor 400, have. According to one embodiment, the first electrode fiber 130 may be used as an anode. According to one embodiment, the second electrode fibers 230 may be used as a cathode. According to one embodiment, a plurality of the supercapacitors 400 may be made of an electrode fabric crossing each other.

When the supercapacitor is manufactured using the first electrode fiber 130 and the second electrode fiber 230, the reduced graphene oxide 120 (not shown) storing negative charges in the first electrode fiber 130 ) And the manganese dioxide (220) that stores positive charges in the second electrode fiber (230) may cause differences in charge storage characteristics. In this case, the storage capacity of the first electrode fiber 130 and the second electrode fiber 230 is low due to the characteristics of the supercapacitor, so that the energy storage amount can be determined.

More specifically, when the supercapacitor is manufactured using the first electrode fiber 130 including the reduced graphene oxide 120 and the second electrode fiber 130 including the manganese dioxide 220, The charge storage characteristics of the first electrode fibers 230 are lower than the charge storage characteristics of the second electrode fibers 130 as the reduced charge storage properties of the graphene oxide 120 are lower than the manganese dioxide 220. [ . Accordingly, the energy storage amount of the supercapacitor can be determined by the first electrode fiber 230.

In order to maximize the energy storage efficiency of the supercapacitor, the supercapacitor according to the embodiment of the present invention and the manufacturing method thereof may provide various methods. Hereinafter, methods for maximizing the energy storage efficiency of the supercapacitor will be described in detail.

The wt% of the reduced graphene oxide 120 in the first electrode fiber 130 is greater than the wt of the manganese dioxide 220 in the second electrode fiber 230 in order to maximize the energy storage efficiency of the supercapacitor. % ≪ / RTI > For example, the reduced graphene oxide 120 may be provided at 90 wt%, and the manganese dioxide 220 may be provided at 70.5 wt%.

If the wt% of the reduced graphene oxide 120 in the first electrode fiber 130 and the wt% of the manganese dioxide 220 in the second electrode fiber 230 are equal to each other, The number of the first carbon nanotube sheets 110 in the one electrode fiber 130 may be greater than the number of the second carbon nanotube sheets 210 in the second electrode fiber 230. In other words, the first electrode fibers 130 may be made thicker than the second electrode fibers 230. For example, the number of the first carbon nanotube sheets 110 may be five, and the number of the second carbon nanotube sheets 210 may be four.

The area of the first carbon nanotube sheet 110 may be larger than the area of the second carbon nanotube sheet 210. The amount of the reduced graphene oxide 120 provided on the first carbon nanotube sheet 110 is controlled by adjusting the amount of the manganese dioxide 220 provided on the second carbon nanotube sheet 210 Can be more.

The supercapacitor according to an embodiment of the present invention includes a first carbon nanotube sheet 110 wound around the reduced graphene oxide 120 and the reduced graphene oxide 120, And a second electrode fiber 230 including the electrode fiber 130 and the manganese dioxide 220 and the second carbon nanotube sheet 220 twisted to surround the manganese dioxide 220. Accordingly, a highly efficient asymmetric supercapacitor including the reduced graphene oxide 120 and the manganese dioxide 220 can be provided.

Also, the supercapacitor may be formed on the first and second carbon nanotube sheets 110 and 210 before the fibers are manufactured using the first and second carbon nanotube sheets 110 and 210, Wherein the graphene oxide 120 and the manganese dioxide 220 are provided and wherein the reduced graphene oxide 120 and the manganese dioxide 220 are provided in the first and second carbon nanotube sheets 110 and 210 may be twisted so that the first and second electrode fibers 130 and 230 may be manufactured. Accordingly, the content of the reduced graphene oxide 120 and the manganese dioxide 220 in the first and second electrode fibers 130 and 230 can be increased and the energy storage amount of the supercapacitor can be improved .

In addition, methods for maximizing the energy storage efficiency of the supercapacitor may be provided.

The weight of the reduced graphene oxide 120 at the first electrode fiber 130 may be greater than the wt% of the manganese dioxide 220 at the second electrode fiber 230. In one embodiment, have.

The number of the first carbon nanotube sheets 110 in the first electrode fibers 130 may be greater than the number of the second carbon nanotube sheets 210 in the second electrode fibers 230. [ Can be many.

According to one embodiment, the area of the first carbon nanotube sheet 110 may be higher than the area of the second carbon nanotube sheet 210.

According to one embodiment, the reduced graphene oxide 120 may be doped with nitrogen.

Accordingly, the energy storage efficiency of the supercapacitor according to the embodiment can be maximized and the energy storage amount can be improved.

Hereinafter, specific experimental examples and characteristics evaluation results of the supercapacitor according to the embodiment of the present invention will be described.

The production of the first electrode fiber according to Example 1

A silicon substrate is prepared. A carbon nanotube forest (CNT forest) having a height of about 400 mu m, a diameter of about 12 nm, and about nine walls was prepared on the silicon substrate by chemical vapor deposition. A carbon nanotube sheet (CNT sheet) having a plurality of carbon nanotubes extending in the first direction was drawn on a glass substrate by pulling the carbon nanotube forest in a first direction.

Reduced graphene oxide (rGO) in nanoflake form and dimethylformamide with 8 mg / ml wt% are prepared. The reduced graphene oxide was mixed with dimethylformamide and dispersed by ultrasonic treatment at 150 W for 1 hour using a VCS750 ultrasonic device to prepare a mixed solution.

After five sheets of the carbon nanotube sheet were stacked, the mixed solution was sprayed by a drop casting method and dried for 20 minutes. The drop casting process and the drying process for 20 minutes were repeated 5 times.

The dried carbon nanotube sheet includes a reduced graphene oxide having about 90 wt% wt% twisted ends of a plurality of the carbon nanotube sheets at about 3000 times per meter using the first direction as a rotation axis A first electrode fiber was prepared.

The production of the second electrode fiber according to Example 2

(MnO ₂ ) nanoparticles prepared from Sigma-Aldrich, having a diameter of 30 nm, a length of 100 nm, and a rod shape, and an ethanol solvent containing wt% of 5 mg / ml are prepared. The manganese dioxide nanoparticles were mixed with ethanol and ultrasonicated to prepare a mixed solution.

Four carbon nanotube sheets prepared by the method according to Example 1 described above were laminated, and the mixed solution was sprayed by a drop casting method and dried for 20 minutes. The dried carbon nanotube sheet is obtained by twisting a plurality of the carbon nanotube sheet ends at about 5000 times per meter using the first direction as a rotation axis to form a second electrode fiber including manganese dioxide having 70 wt% .

Manufacturing of the supercapacitor according to the third embodiment

A PVA-LiCl electrolyte was prepared by mixing PVA having a capacity of 3 g, LiCl having a capacity of 6 g, and DI water having a capacity of 30 ml at a temperature of 90 ° C. Then, the electrolyte was coated on the first electrode fiber according to Example 1 and the second electrode fiber according to Example 2, respectively.

The first electrode fiber coated with an electrolyte was used as a positive electrode, the second electrode fiber coated with an electrolyte was used as a negative electrode, and a copper (Cu) wire having a diameter of 180 μm was connected to each electrode to prepare a supercapacitor.

Supercapacitor fabrication according to Example 4

The PVDF-HFP-TEABF ₄ electrolyte was prepared by mixing a mixture of acetone with PVDF-HFP and a mixture of propylene carbonate and TEABF ₄ in a ratio of 4: 1 and drying on a slide glass for 3 hours. Thereafter, a supercapacitor was manufactured by the method according to the third embodiment described above.

Preparation of electrode fabric according to example 5

The first electrode fiber according to Example 1 described above and the second electrode fiber according to Example 2 were coated with the electrolyte according to Example 3, respectively, and they were woven together to fabricate a textile super capacitor.

Fabrication of the first electrode fiber according to Example 6

The first electrode fiber according to the above-described Example 1 was prepared, and the first electrode fiber was coated with a Na ₂ SO ₄ liquid electrolyte.

The production of the second electrode fiber according to Example 7

The second electrode fiber according to the above-described Example 2 was prepared, and the second electrode fiber was coated with a Na ₂ SO ₄ liquid electrolyte.

The production of the supercapacitor according to Comparative Example 1

The electrode fiber according to Example 1 described above was coated with the electrolyte according to Example 3 and used as a positive electrode and a negative electrode to prepare a supercapacitor.

Preparing the supercapacitor according to Comparative Examples 2 to 7

Comparative Example 2: CNT / MnO ₂ based stretchable asymmetric fibers

Comparative Example 3: rGO / MnO ₂ / PPy yarns

Comparative Example 4: NiOH / MnO ₂ asymmetric yarns

Comparative Example 5: Hollow rGo fiber

Comparative Example 6: MnO ₂ nanosheet decorated asymmetric carbon fibers

Comparative Example 7: MnO ₂ coated stretchable, asymmetric CNT wires

The electrode fibers, supercapacitors and electrode fabrics according to Examples 1 to 5 and Comparative Examples 1 to 6 are summarized in Table 1 below.

division Kinds Configuration Electrolyte Example 1 Electrode fiber rGO / CNT Example 2 Electrode fiber MnO ₂ / CNT Example 3 Super capacitor rGO / CNT, MnO ₂ / CNT PVA-LiCl Example 4 Super capacitor rGO / CNT, MnO ₂ / CNT PVDF-HFP-TEABF ₄ Example 5 Electrode Fabric rGO / CNT, MnO ₂ / CNT PVA-LiCl Example 6 Electrode fiber rGO / CNT Na ₂ SO ₄ Example 7 Electrode fiber MnO ₂ / CNT Na ₂ SO ₄ Comparative Example 1 Super capacitor rGO / CNT,
rGO / CNT PVA-LiCl Comparative Example 2 Super capacitor CNT / MnO ₂ based stretchable asymmetric fibers Comparative Example 3 Super capacitor rGO / MnO ₂ / PPy yarns Comparative Example 4 Super capacitor NiOH / MnO ₂ asymmetric yarns Comparative Example 5 Super capacitor Hollow rGo fiber Comparative Example 6 Super capacitor MnO ₂ nanosheet decorated asymmetric carbon fibers Comparative Example 7 Super capacitor MnO ₂ coated stretchable, asymmetric CNT wires

6 is a photograph of the first electrode fiber included in the supercapacitor according to the first embodiment of the present invention.

6 (a) and 6 (b), the profile and cross section of the first electrode fiber according to Example 1 were measured at a low magnification (scale bar = 300 μm) and a high magnification (scale bar = microscopy.

6 (a), the first electrode fiber according to the first embodiment has a twisted shape, and the reduced graphene oxide (rGO) is formed in a flake form between carbon nanotube sheets And it was confirmed that it existed in. As can be seen from FIG. 6 (b), it was confirmed that the cross section of the first electrode fiber according to Example 1 was spiral. The cross section shows that the carbon nanotube sheet is rolled and stacked, and that reduced graphene oxide is provided between the dried and stacked carbon nanotube sheets.

7 is a photograph of the second electrode fiber included in the supercapacitor according to the second embodiment of the present invention.

Referring to FIGS. 7A and 7B, the profile and cross section of the second electrode fiber according to Example 2 were measured at a low magnification (scale bar = 300 μm) and a high magnification (scale bar = 600 nm) microscopy.

As shown in FIG. 7 (a), the second electrode fiber according to Example 2 has a twisted shape, and manganese dioxide (MnO ₂ ) exists between carbon nanotube sheets in the form of particles . As shown in FIG. 7 (b), it was confirmed that the cross section of the second electrode fiber according to Example 2 was spiral. In addition, the cross section shows that the carbon nanotube sheet is rolled and stacked, and that manganese dioxide (MnO ₂ ) is provided between the dried carbon nanotube sheets.

8 is a graph showing electrochemical characteristics of a supercapacitor according to Comparative Example 1 of the present invention.

8 (a), the supercapacitor according to the comparative example 1 is operated at a voltage scan rate range of 10, 30, 50, 70 and 100 mV / s, The current density was measured and a cyclic voltage-current curve (hereinafter referred to as CV curve) was shown. As can be seen from FIG. 8 (a), the CV curve of the supercapacitor according to Comparative Example 1 does not show a peak in a voltage scan rate range of 10, 30, 50, 70 and 100 mV / s there was. This indicates that the supercapacitor according to Comparative Example 1 is related to the Faradic redox reaction.

Referring to FIG. 8 (b), the supercapacitor according to Comparative Example 3 was measured for voltage over time in a current density range of 0.5, 2.5, and 5 mA / cm ² , and charge / discharge curves. As shown in FIG. 8 (b), it was confirmed that the charge / discharge curve of the supercapacitor according to Comparative Example 1 appeared in a triangular shape in the current density range of 0.5, 2.5, and 5 mA / cm ² .

Referring to FIG. 8C, the areal capacitance (mF / cm ² ) and the linear capacitance (mF / cm) according to the scan rate (mV / s) of the supercapacitor according to the comparative example 1 were measured . As can be seen from FIG. 8 (c), in the supercapacitor according to Comparative Example 1, the areal capacitance gradually decreases at 172 mF / cm ² and the linear capacitance decreases at 17 mF / cm as the scan rate increases I could.

9 is a graph comparing characteristics of the first electrode fibers according to the content of reduced graphene oxide according to an embodiment of the present invention.

Referring to FIG. 9, a first electrode fiber having a first electrode fiber according to Example 1 and a reduced graphene oxide wt% of 18.5 wt% was prepared, and a CV curve was measured by measuring a current density according to a voltage . As can be seen from Fig. 9, the CV of the first electrode fiber with wt% of reduced graphene oxide of 90.3 wt% had a CV curve area of 18.5 wt% and the CV of the first electrode fiber with reduced graphene oxide wt% Which is larger than the curve area. Accordingly, it can be seen that the cyclic voltammetric characteristic is improved by the first electrode fiber having the weight percent of graphene oxide reduced to 90.3 wt%.

10 is a graph comparing the characteristics of the first electrode fiber and the second electrode fiber according to the embodiments of the present invention.

Referring to FIG. 10, currents according to the voltage of the electrode fibers according to the first and second embodiments are measured and the CV curves are shown. In order to measure the current according to the voltage of the electrode fibers according to Examples 1 and 2, a three electrode system was used. Ag / AgCl was used as a reference electrode, and a Pt mesh was used as a counter electrode Respectively. As can be seen from FIG. 10, it was confirmed that the area of the CV curve according to the second embodiment is larger than that of the CV curve according to the first embodiment. Accordingly, it can be seen that the charge storage characteristics of the first electrode including the reduced graphene oxide and the second electrode including the manganese dioxide are different.

11 is a graph showing characteristics of a supercapacitor according to a third embodiment of the present invention.

Referring to FIG. 11A, the current density according to the voltage (V) is measured in a maximum applied voltage range of 0.9, 1.3, 1.7, and 2.1 V according to the third embodiment of the present invention , And a circulating voltage-current curve (hereinafter referred to as a CV curve). The scan rate was measured at 100 mV / s. As can be seen from FIG. 11 (a), the CV curve area of the supercapacitor according to the third embodiment increases gradually in the range of maximum applied voltages of 0.9, 1.3, 1.7, and 2.1V. Also, it was confirmed that the CV curve area in the range of 2.1V maximum applied voltages is similar to the CV curve area of normal supercapacitors. Accordingly, it can be understood that the supercapacitor according to the third embodiment can be applied as a supercapacitor.

11 (b), the supercapacitor according to the third embodiment measures voltages over time in 0.9, 1.3, 1.7, and 2.1 V maximum applied voltage ranges, and calculates a charge / discharge curve Respectively. The current density according to the voltage of the supercapacitor according to Example 3 was measured and the IR drop was measured. As can be seen from FIG. 11 (b), the supercapacitor according to the third embodiment shows a stable inverted triangular charge / discharge curve at the maximum applied voltages of 2.1 V. It was also confirmed that a small IR drop of 47 mV was obtained at a current density of 1.2 mA / cm ² . Accordingly, it can be understood that the supercapacitor according to the third embodiment can be applied as a supercapacitor.

12 is a graph showing the characteristics of the supercapacitor according to the fourth embodiment of the present invention.

12 (a) and 12 (b), the supercapacitor according to the fourth embodiment is applied with a voltage of 0 to 2 voltages (in a voltage scan rate range of 10, 30, 50, 70 and 100 mV / s current density according to the voltage, V, and the current density according to the voltage of 0 to 4 were measured, and a cyclic voltage-current curve (hereinafter referred to as CV curve) was shown. 12 (a) and 12 (b), the CV curve area of the supercapacitor according to the fourth embodiment is the CV curve of the supercapacitor according to the third embodiment described with reference to FIG. 11 (a) It was confirmed that it is larger than the area. Accordingly, it can be seen that the use of the electrolyte of PVDF-HFP-TEABF _{4 has} a higher redox stability than that of PVA-LiCl electrolyte in the case of manufacturing the supercapacitor according to the above embodiment.

Referring to (c) of FIG. 12, the supercapacitor according to the fourth embodiment measures a voltage with time in a voltage range of 3.5 V or higher and shows a charge / discharge curve. As shown in FIG. 12 (c), it can be confirmed that the supercapacitor according to the fourth embodiment exhibits a stable inverted triangular charge / discharge curve. Accordingly, it can be understood that the supercapacitor according to the fourth embodiment can be applied as a supercapacitor.

13 is a graph comparing characteristics of supercapacitors according to embodiments of the present invention.

13 (a), supercapacitors according to the third and fourth embodiments are analyzed by electrochemical impedance spectroscopy (EIS), and an EIS curve is shown. As can be seen from FIG. 13 (a), it was confirmed that all of the supercapacitors according to the third and fourth embodiments exhibited low equivalent series resistance.

Referring to FIG. 13B, the areal capacitance (mF / cm ² ) and the linear capacitance (mF / cm ² ) according to the scan rates (mV / s) of the supercapacitors according to the third and fourth embodiments ) Were measured. As shown in FIG. 13 (b), the areal capacitance and the linear capacitance of the supercapacitor according to the fourth embodiment are lower than the areal capacitance and linear capacitance of the supercapacitor according to the third embodiment.

14 is a graph comparing energy storage characteristics of supercapacitors according to embodiments of the present invention and comparative examples.

14, the areal energy density (μWh / cm ² ) according to the areal power density (mW / cm ² ) of the supercapacitors according to Examples 3, 4 and Comparative Examples 2 to 7 was measured Respectively. As shown in FIG. 14, the supercapacitor according to the third embodiment exhibits 30.1 μWh / cm ² , the supercapacitor according to the fourth embodiment exhibits 43 μWh / cm ² , 18.9 μWh / cm ² , the supercapacitor according to the comparative example 3 shows 9.2 μWh / cm ² , the supercapacitor according to the comparative example 4 shows 10 μWh / cm ² , the supercapacitor according to the comparative example 5 is 6.8 μWh / represents cm ^2, super-capacitor according to Comparative example 6 represents 1.428 μWh / cm ^2, the supercapacitor according to the Comparative example 7 exhibits a 1.26 μWh / cm ^2, example 3 and example 4 shows that the areal energy density of supercapacitors is high. Accordingly, it can be seen that the energy storage characteristics of the supercapacitor using the electrode including the reduced graphene oxide and the electrode including the manganese dioxide as the asymmetric electrode as in the third and fourth embodiments are good.

The linear energy density (E _L , μWh / cm ² ), the areal energy density (E _A , μWh / cm ² ) and the volumetric energy density (E _V , μWh / cm ² ) of various supercapacitors with asymmetric electrodes Can be summarized in Table 2 below.

division Voltage (V) E _L E _A E _V Example 3 2.1 5.5 30.1 3.8 Example 4 3.5 4.5 43 5 MnO ₂ / carbon fiber asymmetric supercapacitor 1.5 0.216 1.43 - MnO ₂ nanosheet / CNT fiber asymmetric supercapacitor 1.5 0.047 1.25 1.57 MnO ₂ / CNT core-sheath fiber Asymmetric supercapacitor 1.5 6.2 18.9 2.98 Ni (OH) ₂ / ordered mesoporous carbon based micro fiber Asymmetric supercapacitor 1.5 - 10 2.16 MnO ₂ / N-doped CNT fiber asymmetric supercapacitor 1.8 - - 5 Co ₃ O ₄ nanowire / graphene fiber Asymmetric supercapacitor 1.5 - - 0.62

15 is a graph showing electrochemical characteristics of a first electrode, a second electrode, and a supercapacitor according to embodiments of the present invention.

Referring to FIG. 15A, the first electrode fiber according to the sixth embodiment measures a current density according to a voltage in a voltage scan rate range of 10, 30, 50, 70 and 100 mV / s And a cyclic voltage-current curve (hereinafter referred to as a CV curve). In order to measure the current according to the voltage of the electrode fiber according to Example 6, a three electrode system was used, and Ag / AgCl was used as a reference electrode and a Pt mesh was used as a counter electrode. As can be seen from FIG. 15A, the CV curve area of the first electrode fiber according to Example 6 increases as the scan rate increases.

Referring to FIG. 15 (b), the second electrode fiber according to the seventh embodiment measures a current density according to a voltage in a voltage scan rate range of 10, 30, 50, 70 and 100 mV / s And a cyclic voltage-current curve (hereinafter referred to as a CV curve). In order to measure the current according to the voltage of the electrode fiber according to Example 7, a three electrode system was used. Ag / AgCl was used as a reference electrode, and a Pt mesh was used as a counter electrode. As can be seen from FIG. 15 (b), the CV curve area of the second electrode fiber according to Example 7 increases as the scan rate increases.

Referring to FIG. 15C, a current density according to a voltage is measured in a voltage scan rate range of 100, 200, 300, 400 and 500 mV / s in the supercapacitor according to the third embodiment , And a circulating voltage-current curve (hereinafter referred to as a CV curve). As can be seen from FIG. 15 (c), it can be seen that as the scan rate increases, the CV curve gradually appears as a stable square shape while maintaining the initial capacitance of 61.8%.

16 is a graph showing electrochemical characteristics of supercapacitors according to embodiments of the present invention.

16 (a) and 16 (b), the supercapacitor according to the fourth and the third embodiments is operated at a voltage scan rate range of 10, 30, 50, 70 and 100 mV / (Hereinafter referred to as a CV curve) was measured. As can be seen from FIGS. 16A and 16B, it can be seen that the CV curves of the supercapacitor according to the fourth and third embodiments are similar to each other. Accordingly, it can be seen that both of PVDF-HEP-TEABF ₄ and PVA-LiCl can be used as an electrolyte in the case of manufacturing the supercapacitor according to the above embodiment.

17 is a graph comparing characteristics of supercapacitors according to the embodiment of the present invention and the comparative example.

Referring to FIG. 17A, areal capacitance (mF / cm ² ) and volumetric capacitance (mF / cm ³ ) are measured according to the scan rate (mV / s) of the supercapacitor according to the third embodiment Respectively. As can be seen from FIG. 17A, it was confirmed that the supercapacitor according to Example 3 exhibits an areal capacitance of 322.4 mF / cm ² and 57.2 mF / cm ³ at a scan rate of 10 mV / s.

Referring to FIG. 17 (b), the capacitance retention (%) according to the scan rate of the supercapacitor according to Example 3 and Comparative Example 1 was measured. As can be seen from FIG. 17B, as the scan rate increases, the amount of decrease in capacitance retention of the supercapacitor according to Comparative Example 1 is significantly higher than that of the supercapacitor according to Embodiment 3 . Accordingly, it can be seen that the use of an asymmetric electrode is more effective in maintaining capacitance retention than a symmetric electrode in manufacturing a supercapacitor according to the embodiment.

FIG. 18 is a graph showing charge / discharge characteristics of a supercapacitor according to the third embodiment of the present invention. FIG.

Referring to FIG. 18 (a), the current density according to the voltage is measured and the CV curve is shown for a case where the supercapacitor according to the third embodiment is charged / discharged once and 1000 times when charged / discharged. As can be seen from FIG. 18 (a), it was confirmed that the CV curve area when the supercapacitor according to the third embodiment was once charged and discharged and the CV curve area when charged and discharged 1000 times were substantially equal .

Referring to FIG. 18 (b), the capacitance retention (C / C ₀ ) according to the number of times of charging and discharging of the supercapacitor according to the third embodiment is measured. As can be seen from FIG. 18 (b), it was confirmed that the capacitance retention was kept substantially constant during charging and discharging of the supercapacitor according to the third embodiment once to 1000 times. Thus, it can be seen that the supercapacitor according to the third embodiment has excellent durability and lifetime characteristics.

FIG. 19 is a photograph of the operation of an electrode fabric and a circuit using the electrode fabric according to the fifth embodiment of the present invention. FIG.

19 (a), the electrode fabric according to the fifth embodiment was photographed. As can be seen from FIG. 19 (a), it can be seen that the electrode fabric according to Example 5 can be made in the form of a regular fabric.

Referring to FIG. 19 (b), a wire and a blue LED of 0.65 W were installed on the electrode fabric according to the fifth embodiment, and a photograph was taken immediately after the circuit was operated. As can be seen from FIG. 19 (b), it was confirmed that the blue LED of 0.65 W was operated due to the electrode fabric according to the fifth embodiment.

Referring to Fig. 19 (c), the above-described circuit (b) of Fig. 19 was operated for 5 minutes and then photographed. As can be seen in FIG. 19 (c), the electrode fabric according to Example 3 has a storage capacity of operating a 0.65 W blue LED for 5 minutes.

20 is a graph showing electrochemical characteristics when the electrode fabrics according to the fifth embodiment of the present invention are connected in series and in parallel.

Referring to FIG. 20 (a), in the case of one electrode fabric according to the fifth embodiment, when two are connected in series, three are connected in series, and four are connected in series, And the CV curve is shown. 20 (a), when the number of electrode fabrics according to the fifth embodiment is increased and connected in series, the area of the CV curve gradually increases as the number of electrode fabrics according to the fifth embodiment increases .

Referring to FIG. 20 (b), when two electrode fabrics according to the fifth embodiment are connected in parallel, three are connected in parallel, and four are connected in parallel, And the CV curve is shown. As can be seen from FIG. 20 (b), when the number of the electrode fabrics according to the fifth embodiment is increased and connected in parallel, as the number of the electrode fabrics according to the embodiment 5 increases at a voltage of 1 V, , Respectively. Thus, it can be seen that the electrode fabric according to the fifth embodiment can be used as a super capacitor.

FIG. 21 is a graph comparing characteristics of the electrode fabric according to the fifth embodiment of the present invention in a case where the electrode cloth is connected in series and a case where the electrode cloth is connected in parallel. FIG.

Referring to FIG. 21, areal energy (μWh / cm ² ) according to the scan rate was measured by connecting four electrode fabrics according to the fifth embodiment in series connection and parallel connection. As can be seen from FIG. 21, when four electrode fabrics according to the fifth embodiment are connected in series, the areal energy of 142 μWh / cm ² is exhibited at a scan rate of 10 mV / s. And 86.2 μWh / cm ² , respectively. Accordingly, it can be seen that, when a plurality of electrode fabrics according to the fifth embodiment are connected, serial connection is more efficient.

22 is a graph showing the durability of the electrode fabric according to the fifth embodiment of the present invention.

Referring to FIG. 22, the current density according to the voltage is measured for a pristine state, a dynamically bent state, and a 100th bent state of the electrode fabric according to the fifth embodiment, Respectively. As can be seen from FIG. 22, it was confirmed that the electrode fabric according to Example 5 was practically identical in the CV curve area in the original state, the dynamically bent state, and the bent state 100 times. Thus, it can be seen that the electrode fabric according to the fifth embodiment has excellent durability.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present invention.

100, 200: substrate
110: first carbon nanotube sheet
120: Reduced graphene oxide
130: first electrode fiber
210: a second carbon nanotube sheet
220: manganese dioxide
230: second electrode fiber
300: electrolyte
400: Super capacitor

Claims (11)

A first electrode fiber comprising a reduced graphene oxide and a first carbon nanotube sheet twisted to surround the reduced graphene oxide;
A second electrode fiber comprising a manganese dioxide, and a second carbon nanotube sheet twisted to surround the manganese dioxide; And
And an electrolyte between the first electrode fiber and the second electrode fiber.
The method according to claim 1,
Wherein the wt% of the reduced graphene oxide in the first electrode fiber is higher than the wt% of the manganese dioxide in the second electrode fiber.
The method according to claim 1,
Wherein the number of the first carbon nanotube sheets in the first electrode fibers is larger than the number of the second carbon nanotube sheets in the second electrode fibers.
The method according to claim 1,
Wherein the reduced graphene oxide comprises nitrogen doped.
The method according to claim 1,
The first and second carbon nanotube sheets are provided in a rolled stacked form,
Wherein the reduced graphene oxide and the manganese dioxide are provided between the first and second carbon nanotube sheets that are laminated and dried, respectively.
The method according to claim 1,
Wherein the first and second electrode fibers extend in a first direction,
Wherein a cross section of the first and second carbon nanotube sheets is provided in a spiral shape in a cross section cut into a first plane having a normal line in the first direction.
The method according to claim 1,
In the first electrode fiber, the wt% of the reduced graphene oxide is higher than the wt% of the first carbon nanotube sheet,
Wherein in the second electrode fiber, wt% of the manganese dioxide is higher than wt% of the second carbon nanotube sheet.
Preparing a first carbon nanotube sheet;
Providing a reduced graphene oxide on the first carbon nanotube sheet;
Twisting the first carbon nanotube sheet provided with the reduced graphene oxide to produce a first electrode fiber;
Preparing a second carbon nanotube sheet;
Providing manganese dioxide on the second carbon nanotube sheet;
Twisting the second carbon nanotube sheet provided with manganese dioxide to produce a second electrode fiber; And
And coating the first and second electrode fibers with an electrolyte.
9. The method of claim 8,
Providing the reduced graphene oxide to the first carbon nanotube sheet, and providing the manganese dioxide to the second carbon nanotube sheet is performed by a solution process.
9. The method of claim 8,
Wherein the step of providing the reduced graphene oxide to the first carbon nanotube sheet comprises:
Preparing a first source solution in which the reduced graphene oxide is dispersed; And
Providing the first source solution on the first carbon nanotube sheet,
Wherein the step of providing the manganese dioxide to the second carbon nanotube sheet comprises:
Preparing a second source solution in which the manganese dioxide is dispersed; And
And providing the second source solution on the second carbon nanotube sheet,
Wherein the wt% of the reduced graphene oxide in the first source solution is higher than the wt% of the manganese dioxide in the second source solution.
9. The method of claim 8,
Wherein the step of providing the reduced graphene oxide to the first carbon nanotube sheet comprises:
Providing a first source solution in which the reduced graphene oxide is dispersed on the first carbon nanotube sheet and drying the first carbon nanotube sheet provided with the first source solution repeated a plurality of times Wherein the step of forming the super capacitor comprises the steps of:

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