KR102014737B1 - A polymer electrolyte comprising amphiphilic copolymer and ionic liquid and a supercapacitor using the same - Google Patents

Abstract

One aspect of the present invention provides a polymer electrolyte comprising a comb-shaped amphiphilic copolymer and an ionic liquid.

Description

A polymer electrolyte comprising an amphiphilic copolymer and an ionic liquid, and a supercapacitor using the same {A POLYMER ELECTROLYTE COMPRISING AMPHIPHILIC COPOLYMER AND IONIC LIQUID AND A SUPERCAPACITOR USING THE SAME}

The present invention relates to a polymer electrolyte comprising an amphiphilic copolymer and an ionic liquid and a supercapacitor using the same.

The development of high efficiency energy storage media, such as fuel cells and supercapacitors, is accelerating to meet the growing demand for energy in the world. Among them, polymer electrolytes are rapidly emerging as candidates for new electrolytes due to advantages such as high ion conductivity and wide available voltage.

Generally, a polymer electrolyte is prepared by combining a polymer matrix with an ion conductive salt that provides free-moving ions. Polymer gel electrolytes exist as intermediates between solids and liquids, and have high mechanical strength and versatility to act as both binders and separators, thus emerging as an alternative to overcome the problems of leakage and stability of existing liquid electrolytes. .

Recently, ionic liquids with high ionic conductivity, wide electrochemically available voltage, incombustibility and high stability have replaced salts of polymer gel electrolytes. In particular, wide available voltages are suitable for energy storage devices with high energy densities such as batteries or supercapacitors.

In supercapacitors, cell voltage and equivalent series resistance (ESR) are proportional to the limiting contact pressure and conductivity of the electrolyte, respectively. Most ionic liquids consist of cations and anions, and because of their large ions, weak interactions are induced and exist in the liquid state at room temperature. Despite its many advantages, the ionic liquid's properties as a liquid at room temperature have limitations in its application to energy storage devices due to leakage and stability problems. Therefore, to solve this problem, there is a need for a host material such as a polymer matrix that can induce immobilization of ionic liquids with adequate mechanical strength.

The shape and properties of polymer gel electrolytes based on ionic liquids are influenced by the interaction between the host polymer and the polymer / ionic liquid. Various polymers (poly (methyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyethylene oxide (PEO), etc.) have been studied as host polymers.

Among them, PEO-based polymers have been actively studied because the interaction between C═O functional groups and cations in ionic liquids increases the ionic conductivity of electrolytes. The interaction of the polymer with the ionic liquid can prevent the ionic liquid from agglomerating and consequently increase the amount of free-moving ions. In addition, the electrochemical and physical properties are also affected by the interaction of the host polymer with the ionic liquid. This interaction increases the miscibility of polymers and ionic liquids and helps to produce stable solid phase electrolytes. However, the high crystallization tendency of PEO also reduces the ionic conductivity by limiting the mobility and flexibility of the polymer chain. One way to prevent the crystallization of PEO is to copolymerize with other monomers. Copolymerization reduces the degree of crystallization by preventing the polymer chains from stacking, while properly polymerized polymers lead to nanostructures. This self-assembly can form ion permeation pathways that can further enhance ion conductivity.

Recently, electric double layer capacitors (EDLCs) with high power density, long life and high capacity are considered to be the next generation energy storage medium. In general, an electric double layer capacitor uses an electrolyte based on polyvinyl alcohol (PVA) based on water as a host polymer. PVA-based electrolytes have flexibility, nontoxicity, and the like suitable for solid-state supercapacitors. However, since PVA is dissolved in water, there are problems in narrow operating voltage and long-term stability, which are disadvantages due to residual moisture.

The present invention is to solve the above-mentioned problems of the prior art, an object of the present invention can improve the ionic conductivity without leakage of the ionic liquid, when applied as a supercapacitor through the interaction between the host polymer and the ionic liquid Long-term stability can be secured, and the nanostructures provide a polymer electrolyte that can be applied as an electrolyte of various energy storage media through the ion conduction pathway.

One aspect of the present invention provides a polymer electrolyte comprising a comb-shaped amphiphilic copolymer and an ionic liquid.

In one embodiment, the comb-shaped amphiphilic copolymer may be a free radical polymerization of a hydrophilic unit portion and a hydrophobic unit portion in a weight ratio of 1: 0.5 to 2.0, preferably 1: 0.5 to 1.0, respectively. As used herein, the term “unit part” is a repeating unit constituting a polymer, and is understood as a concept including a dimer, a trimer, an oligomer, and a block composed of a plurality of monomers as well as a single monomer. Can be.

If the weight ratio of the hydrophilic unit and the hydrophobic unit is outside the range, the comb-like amphiphilic copolymer and the ionic liquid may not be implemented to the extent necessary. Specifically, the comb-shaped amphiphilic copolymer cannot uniformly disperse the ionic liquid, and the ionic liquid is difficult to adequately plasticize the comb-like amphiphilic copolymer.

In one embodiment, the hydrophilic unit portion polyoxyethylene methacrylate, polyhydroxyethyl methacrylate, polyt- butyl methacrylate, polyacrylamide, polyN-vinylpyrrolidone, polyaminostyrene, polystyrene It may be one selected from the group consisting of sulfonic acid, polymethylpropenesulfonic acid, polysulfopropyl methacrylate, polysulfoethyl methacrylate, polysulfobutyl methacrylate, and a combination of two or more thereof, and preferably, polyoxy Ethylene methacrylate may be, but is not limited thereto.

In one embodiment, the hydrophobic unit portion may be 2- [3- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate.

For example, when the hydrophilic unit portion and the hydrophobic unit portion are polyoxyethylene methacrylate and 2- [3- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate, respectively. , The comb-shaped amphipathic copolymer may have a structure of the following formula (1).

<Formula 1>

In one embodiment, the content of the ionic liquid may be up to 60% by weight, preferably 30 to 50% by weight, more preferably 40 to 50% by weight, based on the total weight of the polymer electrolyte. It is not limited to this. When the content of the ionic liquid is more than 60% by weight, the comb-shaped amphiphilic copolymer may be excessively plasticized to reduce workability and moldability, and may optionally leak a polymer electrolyte in a cell or a supercapacitor. On the other hand, when the content of the ionic liquid is less than 30% by weight, the ionic conductivity of the polymer electrolyte may be lowered.

In one embodiment, the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-n-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3- Methylimidazolium bis- (trifluoromethylsulfonyl) imide, 1-n-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-1-methylpyrrolidinium bis (trifluoromethane Sulfonyl) imide, N-methoxyethyl-N-methylpyrrolidinium bis- (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1- Butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium dicyanamide, 11 -Methyl-3-octylimidazolium tetrafluoroborate, N-methyl-N-propylpyreridinium bis (fluorosulfonyl) imide, N-butyl-N-methylpyrrolidinium bis (full Luorosulfonyl) imide and may be one selected from the group consisting of two or more combinations thereof, preferably 1-ethyl-3-methylimidazolium dicyamide, but is not limited thereto.

In one embodiment, the polymer electrolyte may be a solid phase.

Another aspect of the invention, the polymer electrolyte; It provides a supercapacitor comprising; and electrodes located on both sides of the polymer electrolyte.

In one embodiment, the electrode may include a carbon-based material and a binder. The carbon-based material may be one selected from the group consisting of activated carbon, carbon black, graphite, graphene, carbon nanotubes, carbon fiber, fullerene, and combinations of two or more thereof, and preferably, may be activated carbon. It is not limited to this. The binder may be an organic binder and / or an inorganic binder, preferably, an organic binder, and more preferably, PVDF, which is a fluorine-based polymer, but is not limited thereto.

In one embodiment, the capacitance of the supercapacitor may be 100Fg ^{-1 or} more.

The polymer electrolyte according to an aspect of the present invention may include a comb-shaped amphiphilic copolymer and an ionic liquid, and may improve ionic conductivity without leakage of an ionic liquid through interaction between them. The interaction between the copolymer and the ionic liquid ensures long-term stability when applied as a supercapacitor.

It is to be understood that the effects of the present invention are not limited to the above effects, and include all effects deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a schematic diagram of a polymer electrolyte solution and a supercapacitor according to an aspect of the present invention.
Figure 2 is a PBE copolymer, EMIM DCA, and Fourier-transform infrared spectroscopy (FT-IR, Excalibur series, DIGLAS Co., Hannover) analysis of the solution.
Figure 3 is a differential scanning calorimetry (DS, DSC, DSC8000, Perkin Elmer) analysis of the PBE copolymer and the polymer electrolyte solution.
Figure 4 is a transmission electron microscope (Transmission electron microscope, TEM, Zeiss Libra 120, Zeiss, 120kV) image of the PBE copolymer and the polymer electrolyte solution (a) PBE copolymer, (b) Examples 1, (c) Example 2, (d) Comparative Example 1).
FIG. 5 shows (a) Cyclic voltammetry (CV) curves (50 mV / s) and (b) Nyquist diagrams of two battery cells (supercapacitors) prepared in Preparation Examples and Comparative Preparation Examples. plot), (c) Galvanostatic charge-discharge curve.
6 is a photograph of a contact angle experiment of a polymer electrolyte solution carried out on a carbon-based electrode ((a) Comparative Example 2, (b) Example 2).
FIG. 7 shows the electrochemical characteristics of the two-electrode cells of Preparation Example 2 and Comparative Preparation Example 2 ((a) cyclic voltammograms at various voltage scan rates, (b) at various voltage scan rates). Capacitance retention, (c) constant current charge and discharge curves at different current densities, and (d) cyclic voltammograms at different voltage windows).
FIG. 8 shows (a) Ragone plot and (b) cycle stability of two electrode cells of Preparation Example 2 and Comparative Preparation Example 2. FIG.

Hereinafter, with reference to the accompanying drawings will be described the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, it includes not only "directly connected" but also "indirectly connected" with another member in between. . In addition, when a part is said to "include" a certain component, this means that it may further include other components, without excluding the other components unless otherwise stated.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The materials used here are:

-2- [3- (2H-Benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate (BEM, Mw = 323.35 gmol ^-1 )

-poly (oxyethylene methacrylate) (POEM, poly (ethylene glycol) methyl ether methacrylate, density = 1.101g / mL @ 25 ℃, Mn = 500gmol ^-1 )

-Azobisisobutyronitrile (AIBN, Mw = 164.21 gmol ^-1 )

-1-Ethyl-3-methylimidazolium dicyanamide (EMIM DCA)

-activated carbon (AC, DARCO, -100 mesh particle size)

-carbon black (Super P)

-poly (vinylidene fluoride) (PVDF, Mw = ~ 534,000)

-polyvinyl alcohol (PVA, Mw = 89,000-98,000)

-phosphoric acid (H ₃ PO ₄ , 49-51% in H ₂ O)

-N, N-Dimethylformamide (DMF)

-N-Methyl-2-pyrrolidone (NMP)

-tetrahydrofuran (THF)

Carbon paper (SGL-35BC, CNL energy, thickness: 315㎛)

Synthesis Example

A copolymer (hereinafter, "PBE copolymer") was prepared by free radical polymerization of monomers BEM and POEM. 6 g of BEM was dissolved in 70 ml of DMF by stirring at 40 ° C. 4 ml of POEM and 0.002 g of AIBN, an initiator, were put together in a uniformly dissolved solution, and nitrogen gas was injected into the flask for 1 hour to remove the existing air. The copolymerization proceeded at 90 ° C. for 24 hours. After the synthesis was completed, the solution was precipitated in methanol and dissolved in THF for purification and reprecipitated in methanol three times. The synthesized PBE copolymer was a solid in the form of a bendable film.

Example 1

0.1 g of the PBE copolymer obtained in the synthesis example was dissolved in a 1.5 ml mixed solvent in which DMF and NMP were mixed in a volume ratio of 2: 1 to prepare a solution. After sufficient time, 0.05 g of EMIM DCA was added to the solution to obtain a polymer electrolyte solution.

Example 2

0.1 g of the PBE copolymer obtained in the synthesis example was dissolved in a 1.5 ml mixed solvent in which DMF and NMP were mixed in a volume ratio of 2: 1 to prepare a solution. After sufficient time, 0.1 g of EMIM DCA was added to the solution to obtain a polymer electrolyte solution.

Comparative Example 1

0.1 g of the PBE copolymer obtained in the synthesis example was dissolved in a 1.5 ml mixed solvent in which DMF and NMP were mixed in a volume ratio of 2: 1 to prepare a solution. After sufficient time, 0.15 g of EMIM DCA was added to the solution to obtain a polymer electrolyte solution.

Comparative Example 2

1 g of PVA was added to 10 ml of distilled water and dissolved at 80 ° C. for 3 hours to prepare a solution. After the solution was cooled to room temperature, 0.67 g of KOH was added to obtain a PVA / H ₃ PO ₄ polymer electrolyte solution.

Preparation Example 1

2.4 g of activated carbon, 0.15 g of PVDF, and 0.45 g of Super P were added to 17 ml of NMP, followed by stirring for about one day to prepare a carbon slurry. The carbon slurry was coated on carbon paper using an RK control coater (Model 101, Control RK print-Coat Instuments Ltd.) and dried for 24 hours in a vacuum oven at 80 ° C. to remove residual solvent. To prepare an electrode. The active area of the electrode is 1.5 * 2.0 cm ² and the weight of the active material is 0.25 mg.

0.3 ml of the polymer electrolyte solution prepared in Example 1 was uniformly applied to the surface of the electrode by using a drop-casting technique, dried at room temperature for 3 hours to control the evaporation rate of the solvent, and then removing residual solvent. To dry for 24 hours in a vacuum oven at 80 ℃. A pair of electrodes from which the solvent was removed was assembled to face each other in a sandwich form, and then pressurized to prepare a two-electrode cell.

Preparation Example 2

Instead of the polymer electrolyte solution prepared in Example 1, except that the polymer electrolyte solution prepared in Example 2 was used to prepare a two-electrode cell in the same manner as in Preparation Example 1.

Comparative Production Example 1

Instead of the polymer electrolyte solution prepared in Example 1, a two-electrode cell was prepared in the same manner as in Preparation Example 1 except that the polymer electrolyte solution prepared in Comparative Example 1 was used.

Comparative Production Example 2

Instead of the polymer electrolyte solution prepared in Example 1, a two-electrode cell was prepared in the same manner as in Preparation Example 1 except that the polymer electrolyte solution prepared in Comparative Example 2 was used.

Experimental Example 1

Figure 2 is a PBE copolymer, EMIM DCA, and Fourier-transform infrared spectroscopy (FT-IR, Excalibur series, DIGLAS Co., Hannover) analysis of the solution.

Referring to FIG 2, a carbonyl group (C = O) with an ether group 1724cm ^-1 1100cm ^-1 peak and a peak indicating the (COC) has appeared in PBE copolymer. After addition of EMIM DCA, the size of the 1100 cm ^-1 peak representing the ether group was reduced and an additional 1130 cm ^-1 peak appeared. In addition, the peak of the nitrile functional group of the EMIM DCA changed from 2125 cm ⁻¹ to 2132 cm ⁻¹ . The peak change of the functional groups of the PBE copolymer and the EMIM DCA confirmed the existence of the interaction between the polymer matrix PBE copolymer and the ionic additive EMIM DCA.

In particular, EMIM DCA primarily interacted with selectively hydrophilic POEM chains, suggesting the possibility of forming hydrophilic ion conductive pathways within the polymer matrix. This particular interaction between the polymeric matrix and the ionic additive can ensure high miscibility and ionic conductivity between the two.

Figure 3 is a differential scanning calorimetry (Differential scanning calorimetry, DSC, DSC8000, Perkin Elmer) analysis of the PBE copolymer and the polymer electrolyte solution. The measurement was carried out by raising the temperature to 10 ° C. per minute under a nitrogen environment.

Referring to FIG. 3, the PBE copolymer did not exhibit melting points like other general amorphous polymers. This indirectly indicates that the PBE copolymer is suitable as a matrix of the polymer electrolyte, since the permeation of the ions takes place mostly in the amorphous phase in the polymer electrolyte.

As the ratio of EMIM DCA in the polymer electrolyte solution was increased, the glass transition temperature became lower. This is because the plasticizing effect of EMIM DCA causes the polymer chains to loosen, making the polymer matrix more flexible.

As such, the interaction of the PBE copolymer with the EMIM DCA effectively prevents the aggregation of the EMIM DCA, thereby increasing the concentration of uniformly distributed ions in the electrolyte, and increasing the mobility of the polymer chain due to the plasticizing effect of the EMIM DCA. Since the mobility of the furnace ions increases, the ion conductivity of the prepared polymer electrolyte solution may be improved.

Figure 4 is a transmission electron microscope (Transmission electron microscope, TEM, Zeiss Libra 120, Zeiss, 120kV) image of the PBE copolymer and the polymer electrolyte solution (a) PBE copolymer, (b) Examples 1, (c) Example 2, (d) Comparative Example 1).

Referring to FIG. 4, worm-like fine phase separation was observed due to the difference in solubility between the POEM chain and the PBEM chain in the PBE copolymer. Since the electron density is higher than that of the POEM chain, the BEM portion is dark and the POEM portion is bright.

For Example 1 with the addition of a small amount of EMIM DCA, EMIM DCA was uniformly dispersed in the polymer matrix in the form of black dots. In Example 2, the added EMIM DCAs began to form a structure in which they were connected to each other, which helped to maintain the high conductivity of the ionic liquid in the polymer matrix. On the other hand, when the excessive amount of EMIM DCA as in Comparative Example 1, the region of the EMIM DCA was dominant, the lack of the polymer matrix region may cause problems of physical strength and leakage in the manufacturing to the electrode later.

Experimental Example 2

Table 1 below shows the conductivity and state of the polymer electrolyte solution obtained in Examples and Comparative Examples, and the capacitance of the two-electrode cell (supercapacitor) obtained in Preparation Example and Comparative Preparation Example. Ion conductivity of the polymer electrolyte solution was measured using a ZAHNER IM-6 impedance analyzer. The polymer electrolyte solution was placed between two stainless steel plates at room temperature and analyzed in the range of 1 Hz to 1 MHz.

division Conductivity (S cm ^-1 ) condition Capacitance (F g ^-1 ) PBE Copolymer <5.0 * 10 ^-6 solid - Example 1 (Manufacturing Example 1) 2 * 10 ^-4 solid 107.4 Example 2 (Manufacturing Example 2) 1.3 * 10 ^-3 solid 125.1 Comparative Example 1 (Comparative Production Example 1) 2.7 * 10 ^-3 leakage - Comparative Example 2 (Comparative Production Example 2) 5.5 * 10 ^-4 solid 39.5

Referring to Table 1, it is determined that the ion conductivity of the pure PBE copolymer is too low to be used as an electrolyte of the supercapacitor. In addition, as the amount of EMIM DCA in the polymer electrolyte solution increased, the ionic conductivity tended to increase. In particular, when the excess EMIM DCA was added in accordance with that expected in the TEM image analysis, the plasticizing effect and the Lack of film formation was impossible.

FIG. 5 shows (a) Cyclic voltammetry (CV) curves (50 mV / s) and (b) Nyquist diagrams of two battery cells (supercapacitors) prepared in Preparation Examples and Comparative Preparation Examples. plot), (c) Galvanostatic charge-discharge curve.

Referring to Figure 5 (a), in the case of Preparation Examples 1, 2, and Comparative Preparation Example 1 using the polymer electrolyte solution containing the PBE copolymer significantly increased the capacitance compared to Comparative Preparation Example 2. The high capacitance is due to the high ion conductivity described above and the good affinity between the electrode / electrolyte. In addition, the cyclic voltammetry curve of Preparation Example 2 had a square shape in the form of ideal electric double-layer capacitors (EDLC) and showed the highest capacitance. From this, it can be seen that, as in the case of Preparation Example 2, an appropriate amount of EMIM DCA ionic additive not only provides additional amounts of ions, but also simultaneously provides high ion mobility while maintaining appropriate mechanical strength of the polymer matrix.

In FIG. 5 (b), since all supercapacitors are made of the same carbon-based electrode, it is assumed that the electrochemical difference is derived from the electrolyte. Electrical series resistance (ESR), which appears as a contact with the real axis in the high frequency region, is closely related to the resistance of the electrolyte. Referring to FIG. 5 (b), the ESR values obtained from the diagrams represented 2.21 Ω, 3.65 Ω, and 7.27 Ω in the order of Preparation Example 2, Preparation Example 1, and Comparative Preparation Example 2, respectively. The tendency of these ESR values is consistent with the tendency of the conductivity of the electrolyte.

In the low frequency region, the vertical line is related to the diffusion of electrolyte into the electrode. The closer the line is to the vertical, the closer to the ideal electric double-layer capacitors (EDLC). The graphs of Preparation Examples 1 and 2 and Comparative Preparation Example 1 were closer to vertical than Comparative Preparation Example 2, and it was confirmed that the mobility of ions of the polymer electrolyte solution containing the PBE copolymer, which was previously expected, was better.

In the galvanostatic charge-discharge (GCD) curve of FIG. 5 (c), an IR drop related to the internal resistance was observed at the beginning of the discharge curve. The degree of IR drop was consistent with the trend of ESR.

In particular, the maximum value of the capacitance of the two-electrode cell obtained in Production Example 2 is 125.1 Fg ⁻¹ , which can be largely divided into two reasons. First, the interaction of EMIM DCA and PBE copolymers helped to uniformly disperse EMIM DCA in the polymer matrix, which could lead to the formation of microstructures. Second, due to the plasticizing effect of EMIM DCA This is because the diffusion of ions accelerated.

Figure 6 is a photograph of the contact angle experiment of the polymer electrolyte solution carried out on the carbon-based electrode ((a) Comparative Example 2, (b) Example 2). Contact angle measurements were made after 30 seconds had elapsed after the polymer electrolyte solution was dropped onto the electrode. The better the affinity between the electrode and the electrolyte, the more the contact angle tends to decrease.

Referring to FIG. 6, the polymer electrolyte solution of Example 2 showed a much lower contact angle than that of Comparative Example 2. This is due to the introduction of EMIM DCA, which has a low viscosity and the solvent (DMF, NMP) of the polymer electrolyte solution of Example 2 is closer to hydrophobicity than water. Improved wettability may allow the electrolyte to improve the surface accessibility of the electrode resulting in better electrochemical properties.

FIG. 7 shows the electrochemical characteristics of the two-electrode cells of Preparation Example 2 and Comparative Preparation Example 2 ((a) cyclic voltammograms at various voltage scan rates, (b) at various voltage scan rates). Capacitance retention, (c) constant current charge and discharge curves at different current densities, and (d) cyclic voltammograms at different voltage windows).

Referring to FIG. 7A, the two-electrode cell of Preparation Example 2 maintained an ideal rectangular curve even at a fast scan rate.

Figure 7 (b) With reference to, in the fast scan rate of ^-1 100mVs case of Preparation Example 2 Initial (2mVs ^-1) while maintaining the 69.9% of the capacitance, compared to the case of Preparation Example 2, man 31% of the initial capacity Maintained. Excellent capacitance retention is due to fast ion transport and rearrangement in the electrolyte due to high ion conductivity. Through these results, it can be seen that the polymer electrolyte solution prepared in Example may be applied to a high power supercapacitor in the future, and may be used even at a high scanning rate.

Referring to FIG. 7C, no significant IR drop or distortion of the curve was observed at all current densities.

Referring to FIG. 7 (d), no peak of Faraicic reaction was observed up to 1.6 V, whereas the current density increased rapidly in the high voltage range (> 1.6 V), which is irreversible. It indicates that a positive reaction has occurred. Therefore, the two-electrode cell of Preparation Example 2 can be stably driven to a voltage range of 0 ~ 1.6V, it can be seen that the electric double layer process is dominant within this range.

FIG. 8 shows (a) Ragone plots and (b) cycle stability of the two-electrode cells of Preparation Example 2 and Comparative Preparation Example 2. FIG.

The energy density and power density can be calculated by various electrochemical factors, for example, by the following equation.

E: energy density (Whkg ^-1 )

C: capacitance (F g ^-1 )

ΔV: voltage applied during charging and discharging (V)

P: power density (Wkg ^-1 )

t: discharge time (s)

Refer to the Ragone plot of energy density and power density as compared to Comparative Example 2 (15.2 Whkg ^-1 ) at the same voltage (0.8 V) for Manufacturing Example 2 (34.2 Whkg ^-1 ). Has a high energy density.

The electrolyte of Comparative Example 2 based on PVA uses phosphoric acid in the presence of water, so that the available voltage is limited to 1 V or less, whereas the electrolyte of Example 2 has a stable and wide available voltage provided from EMIM DCA. This allows higher energy densities to be obtained. As the voltage range increased from 0.8V to 1.5V, the energy density continued to increase.

Looking at the cycle stability of the two-electrode cell through Figure 8 (b), in the case of Preparation Example 2 shows excellent stability to maintain 91.1% of the initial capacitance after 10,000 charge and discharge, whereas in Comparative Preparation Example 2 initial capacity Only 62.7% of the time. Electrolytes based on ionic liquids have a reduced capacitance due to aggregation or aging of ionic liquids during charging and discharging. However, as shown in the TEM image, the polymer electrolyte solution of Example 2 was uniformly dispersed through the interaction of the EMIM DCA with the polymer matrix, thereby effectively preventing the aggregation of the ionic liquid and preventing the initial ionic conductivity. You can keep it going.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the invention is indicated by the following claims, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the invention.

Claims (11)

Comb-shaped amphipathic copolymer and ionic liquid,
The comb-shaped amphiphilic copolymer comprises a polyoxyethylene methacrylate hydrophilic unit portion and 2- [3- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate hydrophobic unit portion; ,
And the ionic liquid is 1-ethyl-3-methylimidazolium dicyamide. The method of claim 1,
Wherein the comb-shaped amphiphilic copolymer is a polymer electrolyte that is free radically polymerized in a weight ratio of 1: 0.5 to 2.0 of the hydrophilic unit portion and the hydrophobic unit portion, respectively. delete delete The method of claim 1,
The content of the ionic liquid is 60% by weight or less based on the total weight of the polymer electrolyte, the polymer electrolyte. The method of claim 5,
The content of the ionic liquid is 30 to 50% by weight based on the total weight of the polymer electrolyte, the polymer electrolyte. delete The method of claim 1,
Wherein said polymer electrolyte is in a solid phase. The polymer electrolyte according to any one of claims 1, 2, 5, 6 and 8; And
Supercapacitor comprising; electrodes located on both sides of the polymer electrolyte. The method of claim 9,
The electrode includes a carbon-based material and a binder, supercapacitor. The method of claim 9,
The capacitance of the supercapacitor is 100Fg ^-1 or more, supercapacitor.

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