Patent Application
20250062079
The present invention relates to a composite in which a defect-induced carbon body and a metal oxide are coupled, a method for producing a composite in which a defect-induced carbon body and a metal oxide are coupled, and an energy storage device including a composite electrode in which a defect-induced carbon body and a metal oxide are coupled.
Recently, interest in technology has moved beyond small mobile devices such as smartphones and tablets to large mobile devices such as electric vehicles, self-driving cars, and self-generated IoT systems.
As interest in such mobile devices has increased, research and development on energy storage systems (ESS) is also actively conducted. An example of energy storage systems includes a battery, a supercapacitor, or the like.
Among these, the supercapacitor is an energy storage device that uses adsorption and desorption reactions of physical ions.
In general, a supercapacitor is composed of an activated carbon electrode that physically adsorbs and desorbs ions, a cellulose-based porous separator that separates the ions, a current collector that serves as a passage for the flow of charges, and an electrolyte that provides a charge carrier.
An element that has the greatest impact on the performance of a supercapacitor is a carbon electrode material, which requires a large specific surface area, chemical resistance, a low thermal expansion rate, and high electrical conductivity to increase the performance of the supercapacitor.
The present invention provides a composite with improved electrochemical properties in which a carbon body and a metal oxide are coupled, and a method for producing the composite.
The present invention also provides an energy storage device including, as an electrode, a composite with improved electrochemical properties in which a carbon body and a metal oxide are coupled.
Meanwhile, other objects of the present invention that are not specified will be further considered within the scope that can be easily derived from the following detailed description and the effects thereof.
In order to achieve the objectives proposed above, the following solution means are proposed.
In accordance with an exemplary embodiment of the present invention, there is provided a composite including a defect-induced carbon body and a metal oxide coupled to the carbon body.
In an embodiment, the metal oxide may be a nickel-cobalt oxide.
In an embodiment, the metal oxide may be NiCo2O4.
In an embodiment, in the carbon body, the contact angle of a precursor solvent of the metal oxide with respect to the surface of the carbon body may be about 25 degrees to about 35 degrees due to the induced defect.
In an embodiment, the carbon body may have a dimple or spherical protrusion formed on the surface thereof.
In an embodiment, the metal oxide may be coupled in the form of a protrusion formed by aggregation of a plurality of particle phases on the surface of the carbon body.
In accordance with another embodiment of the present invention, an energy storage device includes, as an electrode, a composite including a defect-induced carbon body and a metal oxide coupled to the carbon body.
In accordance with yet another embodiment of the present invention, a method for producing a composite is a method for producing a composite including a defect-induced carbon body and a metal oxide coupled to the carbon body, and includes the steps of: (a) inducing defects in a carbon body through a Joule-heating process; (b) contacting the defect-induced carbon body with a solution containing a metal oxide precursor; and (c) applying heat to the carbon body in contact with the metal oxide precursor to decompose the precursor, and synthesizing a metal oxide.
In another embodiment, the Joule-heating process of the step (a) may be performed by applying a current of about 260 J/cm2 to about 780 J/cm2 to the carbon body.
In another embodiment, the metal oxide precursor solution may be a solution in that a nickel nitrate and a cobalt nitrate are dissolved in a solvent.
In another embodiment, the step (c) may be performed by a Joule-heating process, and performed by flowing a current of about 25 J/cm2 to about 50 J/cm2 for about 0.3 seconds to about 1 second.
A composite according to an embodiment of the present invention induces defects in a carbon body, thereby improving interfacial properties between the carbon body and a metal oxide, and has an increased contact area, thereby improving electrochemical properties of the composite.
Therefore, by using a composite in which a defect-induced carbon body and a metal oxide are coupled, such as a supercapacitor, as an electrode for an energy storage device, the performance of the energy storage device is improved.
Meanwhile, a method for producing a composite according to another embodiment of the present invention enables the synthesis of the composite within a few seconds through a Joule-heating process, and thus, may significantly reduce the production time and production cost.
Although not explicitly stated herein, it should be understood that effects described in the following specification that are expected by the technical features of the present invention and their provisional effects are treated as described in the specification of the present invention.
The accompanying drawings are exemplified by reference for an understanding of the technical idea of the present invention, and the scope of the present invention is not limited thereto.
Hereinafter, with reference to the drawings, the configuration of the present invention guided by various embodiments of the present invention, and effects resulting from the configuration will be described. In describing the present invention, detailed descriptions of related known functions will be omitted when it is determined that the detailed descriptions may unnecessarily obscure the gist of the present invention that is apparent to those skilled in the art.
A composite of the present invention includes a defect-induced carbon body and a metal oxide coupled to the carbon body.
Defects induced in the carbon body is caused by an artificial process.
That is, sudden thermal energy is applied to the carbon body through the Electrothermal Waves (ETW) process to induce defects, and the induced defects adjust the contact angle and nucleation rate of a metal oxide precursor solution with respect to the surface of the carbon body.
The microstructure and chemical composition of the metal oxide are controlled by the defects induced in the carbon body.
If the above-described composite of the present invention is used as an energy storage device, the performance is improved.
For example, if the composite of the present invention is used as an electrode of a supercapacitor, the supercapacitor is confirmed to have a capacitance retention rate improved by about 60% or greater, have a high specific capacitance of about 1925 F/g at a scan rate of about 1 mV/s, and exhibits high durability in a long-term maintenance test of 28,000 cycles.
Meanwhile, a method for producing a composite according to another embodiment of the present invention enables the synthesis of the composite within a few seconds through a Joule-heating process, and thus, has the advantage of significantly reducing the production time and production cost.
Hereinafter, embodiments and effects thereof will be described in detail with reference to the production method.
Hereinafter, with reference to
The production method M100 of a composite in accordance with an exemplary embodiment of the present invention includes S10 inducing defects in a carbon body through a Joule-heating process, S20 contacting the defect-induced carbon body with a solution containing a metal oxide precursor, and S30 applying heat to the carbon body in contact with the metal oxide precursor to decompose the precursor, and synthesizing a metal oxide.
As a carbon body, a carbon material such as carbon fiber, graphene, and activated carbon may be used.
The carbon material may be used in the form of a sheet, but the present invention is not limited thereto.
Defects are induced in the prepared carbon body through a Joule-heating process.
That is, electrodes for applying electricity are connected to both ends of the prepared carbon body and then electricity is applied thereto.
The energy density of the electricity applied to induce defects in the carbon body may be controlled to be about 260 J/cm2 and to about 780 J/cm2.
If the energy density of the applied electricity is less than about 260 J/cm2, there is a lack of induced defects, and if greater than about 780 J/cm2, the microstructure and chemical properties of a metal oxide are degraded due to excessive defects.
2. S20 Contacting Defect-Induced Carbon Body with Solution Containing Metal Oxide Precursor
As a metal oxide, a nickel-cobalt oxide was used. However, the present invention is not limited thereto, and it may be possible to use other types of metal oxides.
A metal oxide precursor solution for forming a composite is prepared. A solution in which a metal oxide precursor is dissolved in a solvent may be used. If the metal oxide is the nickel-cobalt oxide, a Ni nitrate hexahydrate and a Co nitrate hexahydrate may be dissolved in an acetone solvent and prepared.
The prepared metal oxide precursor solution may be brought into contact with the defect-induced carbon body. Bringing the metal oxide precursor solution into contact with the defect-induced carbon body may be performed by dip-coating, spin-coating, spray-coating, or drop-casting.
The metal oxide precursor solution is brought into contact with the defect-induced carbon body, and then may be dried for a predetermined period of time.
3. S30 Applying Heat to Carbon Body in Contact with Metal Oxide Precursor to Decompose Precursor, and Synthesizing Metal Oxide
The present step may be performed by a Joule-heating process in which heat is applied to the carbon body in contact with the metal oxide precursor.
For example, electrodes are connected to both ends of the carbon body in contact with the metal oxide precursor and then electricity is applied thereto.
At this time, the applied electricity may have an energy density of about 25 J/cm2 to about 50 J/cm2.
The precursor is decomposed by heat generated by the application of electricity described above, and reaches a temperature at which the precursor is synthesized into an oxide.
Through the step S30, a composite in which the metal layer is coupled to a carbon fiber sheet is produced.
As a carbon body, a carbon fiber (CF) sheet (WizMac, HCP030, hydrophilic, 300 μm thick, Korea) was prepared.
The prepared carbon fiber sheet was cut into 2 cm×1 cm to induce defects through a Joule-heating process. The size of the carbon fiber sheet is for experimental purposes only, and the present invention is not limited thereto.
Electrical clamps were connected to both ends of the cut carbon fiber sheet, and a programmable DC power supply (Unicorn TMI, Udp-3050, Korea) was used to apply electricity to perform the Joule-heating process. The application time was controlled to be 0 s, 2 s, 4 s, 6 s, and 8 s. That is, the input energy density was controlled to be 0, 260 J/cm2, 520 J/cm2, 780 J/cm2, and 1,040 J/cm2 (DC Power: 260 W=13 V×20 A), and the cooling time was set to 10 seconds at room temperature.
The carbon fiber sheet was once again cut into 2 cm×0.5 cm to couple a metal oxide.
Specifically, 0.33 M of a Ni nitrate hexahydrate (Ni(NO3)2·6H2O, DAEJUNG, Mn˜290.79, ≥97% Korea) and 0.66M of a Co nitrate hexahydrate (Co(NO3)2·6H2O, Mn˜291.03, ≥98%, Sigma-Aldrich) were dissolved in 1 M of an acetone solvent to prepare a metal oxide precursor solution.
The prepared metal oxide precursor solution was mixed for about 10 minutes using an ultrasonic treatment device. 2 μl of the metal oxide precursor solution was loaded onto the carbon fiber sheet by the drop-casting method to be brought into contact with the sheet.
Thereafter, the carbon fiber sheet was dried for 6 hours at room temperature.
Electricity was applied to the carbon fiber sheet in contact with the metal oxide precursor solution through electrical clamps at both ends of the sheet.
65 W (6.5 V×10 A) of electricity was applied to the carbon fiber sheet in contact with the metal oxide precursor solution for 0.5 s to produce a composite in which a nickel-cobalt oxide is coupled to the carbon fiber sheet.
Properties of the composite of Example described above were evaluated.
The surface shape of the composite was examined by a field emission scanning electron microscope (SEM; FEI, Model Quanta 250 FEG; Jeol, Model JSM-6701F), and the particle size was measured using Image J software.
The chemical composition of the complex was analyzed by X-ray photoelectron spectroscopy (XPS; Ulvac-phi, X-tool) and X-ray diffraction (XRD; Rigaku, SmartLab), and the elemental distribution was measured by energy dispersive X-ray spectroscopy (EDX; FEI, Tecnai G2 F30ST), and chemical reactions were measured using thermogravimetric analysis (TGA, TA instrument, SDTQ600/DSCQ20 System, USA).
The contact angle of the metal oxide precursor solution with respect to the carbon body was measured using a microscope (Macro 105 mm, f/2.8D, Nikon).
The composite was used as an electrode of a half-cell supercapacitor (three-electrode method).
The electrochemical performance of the half-cell supercapacitor including the composite as an electrode was examined using a potentiostat/galvanostat (Gamry Instruments Interface 1000E), including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD).
A reference electrode and a counter electrode of the half-cell supercapacitor were Hg/HgO and a Pt wire, and a potassium hydroxide (KOH) aqueous solution (5.5 M) was used as an electrolyte.
The scan rate of the CV test was controlled from 1 mV/s to 100 mV/s in a potential window of 0.5 V.
The frequency range of the EIS analysis was set from 10-1 Hz to 105 Hz.
The electrical resistance was measured using a digital multimeter (Fluke 1557).
Defects induced in the carbon body are formed by the Joule-heating process, and are mainly induced by the oxidation of carbon on the surface of the carbon body.
Such defects induced in the carbon body affect the crystal size and particle distribution of a metal oxide coupled to the carbon body. That is, the contact angle and nucleation energy of the metal oxide precursor solution with respect to the carbon body are adjusted.
Meanwhile, when measured, the average temperature at the time of applying electricity through the electrical clamps at both ends of the carbon fiber sheet in contact with the metal oxide precursor solution increased to 598° C. within 0.67 seconds, and the thermogravimetric analysis of the composite showed no residual nitrate. That is, the metal oxide precursor in the carbon fiber sheet in contact with the metal oxide precursor solution was completely decomposed and converted into a metal oxide.
The metal oxide produced in Example was a Ni—Co spinel crystal (NiCo2O4).
Referring to
The metal oxide serves an active material for electrochemical energy conversion in an energy storage device such as a supercapacitor, and the defect-induced carbon body provides an additional conductive path to a charge carrier along the interface between the active materials.
Referring to
If no defects are induced in the carbon body, it can be seen that the surface of the carbon body is smooth, and that the metal oxide is excessively aggregated and formed at a specific location.
In comparison, if the energy density of electricity applied to induce defects in the carbon body is controlled to be 260 J/cm2 to 780 J/cm2, it can be seen that defects are evenly formed on the surface of the carbon body, and accordingly, the metal oxide is evenly dispersed and formed.
However, if the energy density of electricity applied to induce defects in the carbon body is greater than 780 J/cm2, excessive defects are formed, and the metal oxides are not evenly formed.
The effect of defects induced in the carbon body on the shape of the composite attributes to the surface energy of a carbon substrate which affects the nucleation process when the metal oxide precursor solvent evaporates.
Referring to
In the case in which no defects are induced in the carbon body, the contact angle of the metal oxide precursor solvent with respect to the carbon body surface was about 41.63 degrees. whereas the contact angle of the metal oxide precursor solvent with respect to the carbon body in which defects were induced by applying electricity with an energy density of about 260 J/cm2 was 32.61 degrees, which is reduced by about 21.67%. Furthermore, the contact angle of the metal oxide precursor solvent with respect to the carbon body in which defect were induced by applying electricity with an energy density of 1,040 J/cm2 was decreased to about 21.11 degrees. Accordingly, as can be seen in
In the case of a nickel-cobalt oxide, the more the Ni2+ and Co3, the more stable the crystals, and referring to
As can be seen in
Additional analysis was conducted to analyze the reason for improvement in the performance of the supercapacitor as charging and discharging were repeated, and the results are shown in
Referring to
The scope of protection of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it should be added once again that the scope of protection of the present invention may not be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0011997 | Jan 2022 | KR | national |
This application is a National Stage of International Application No. PCT/KR2022/018396, filed on Nov. 21, 2022, which is based upon and claims the benefit of priority to Korean Patent Application No. 10-2022-0011997, filed on Jan. 27, 2022, in the Korean Intellectual Property Office. All of the aforementioned applications are hereby incorporated by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/018396 | 11/21/2022 | WO |
