Novel compound, method for preparing same, and supercapacitor electrolyte solution comprising novel compound

Abstract

An electrolyte solution comprising: an ionic salt compound represented by chemical formula 2; and (ii) an electrolyte solution comprising an electrolytic solvent, wherein the ionic salt compound content is 20-50 weight parts relative to 100 weight parts of the electrolyte solution, and the electrolytic solvent is acetonitrile, glutaronitrile (GN), or a mixture thereof.

Description

Novel compound, method for preparing the same, and supercapacitor electrolyte solution comprising the novel compound

[0001] The present invention relates to a novel compound, a method for preparing the same, a supercapacitor electrolyte solution comprising the novel compound, and a novel supercapacitor employing the electrolyte solution. By employing the novel compound, a novel electrolyte solution is provided that exhibits improved charge capacity compared to existing supercapacitors.

[0002] Supercapacitors, also known as ultracapacitors or ultra-high-capacity capacitors, are capacitors with extremely large storage capacities. Unlike batteries that utilize chemical reactions, supercapacitors utilize simple ion migration at the electrode-electrolyte interface or surface chemical reactions for charging and discharging. This allows for rapid charging and discharging, and their high charge-discharge efficiency and long cycle life make them ideal for use as auxiliary batteries or as a replacement for conventional batteries. Supercapacitors boast high power density, fast charge-discharge speeds, and an exceptionally long charge-discharge cycle life of over 500,000 cycles.

[0003] To accelerate a vehicle rapidly, lithium secondary batteries must provide sufficient power. However, due to their inherent slow charging and discharging characteristics, they are unable to provide sufficient power for rapid acceleration. Therefore, supercapacitors are being used as auxiliary batteries in electric vehicles to provide sufficient energy for rapid acceleration. (See (1) Republic of Korea Patent Publication No. 10-2023-0107105 (published on July 14, 2023) and (2) Republic of Korea Patent Publication No. 10-1558959 (published on October 12, 2015).

[0004] The reason supercapacitors have better output than lithium-ion batteries is simply because energy is transferred through the movement of the electrolyte between the cathode and anode. Lithium-ion batteries, on the other hand, charge and discharge through chemical redox reactions, requiring lithium ions to move between the cathode and anode. This slows down their charging and discharging processes. Consequently, lithium-ion batteries take longer to charge and have lower output when discharging.

[0005] As previously explained, supercapacitors charge and discharge without chemical redox reactions, enabling high output. With sufficient charging equipment, a full charge can be achieved in just one to two minutes. Furthermore, because charging and discharging occurs without chemical reactions or movement of lithium ions, supercapacitors have a much longer lifespan, approximately 20 times longer than lithium secondary batteries. Furthermore, because supercapacitors do not utilize chemical reactions, their performance deteriorates little at high or low temperatures. This means they charge and discharge well even in extreme temperatures, down to -20°C (-20°F) and above 50°C (122°F).

[0006] Although supercapacitors outperform lithium secondary batteries in most performance areas, their charge capacity, or energy density, is only about 1 / 20 that of lithium batteries. Because supercapacitors' low storage capacity inherently makes them critically vulnerable to use as energy storage devices, they have been used primarily as auxiliary batteries to supplement output and in specialized applications such as high-power tools. (1) Republic of Korea Patent Publication No. 10-2023-0107105 (Published: July 14, 2023); (2) Republic of Korea Patent Publication No. 10-1558959 (Published: October 12, 2015); (3) Republic of Korea Patent Publication No. 10-2022-0106260 (Published: July 29, 2022); (4) Republic of Korea Patent Registration No. 10-1583525 (Published: January 11, 2016); (5) See Korean Patent Publication No. 10-2023-0035465 (publication date: 2023-03-13); and (6) Korean Patent Registration No. 10-2508004 (publication date: 2023-03-09).

[0007] To increase the energy density of supercapacitors, a critical weakness of supercapacitors, lithium-ion supercapacitors, a hybrid form of supercapacitors and lithium-ion batteries, have been developed. However, limitations in available electrolytes limit the potential for increasing the energy density of supercapacitors. (7) See Republic of Korea Patent No. 10-1724434 (Published: April 18, 2017).

[0008] Acetonitrile is used as a solvent for the electrolyte in supercapacitors, and since the solvent must not undergo a redox reaction below the charging voltage of 4 V, acetonitrile is used. The electrolyte that must have excellent solubility in acetonitrile solvent, and especially has excellent solubility even at low temperatures, is tetrabutylammonium tetrafluoroborate. Therefore, tetrabutylammonium tetrafluoroborate was used as the electrolyte of the supercapacitor. That is, the conventional supercapacitor electrolyte solution is composed of tetrabutylammonium tetrafluoroborate electrolyte salt and acetonitrile solvent. (1) Republic of Korea Patent Publication No. 10-2023-0107105 (Publication date: 2023-07-14); (2) Korean Patent Publication No. 10-1558959 (published on October 12, 2015); (3) Korean Patent Publication No. 10-2022-0106260 (published on July 29, 2022); (4) Korean Patent Registration No. 10-1583525 (published on January 11, 2016); (5) Korean Patent Publication No. 10-2023-0035465 (published on March 13, 2023); and (6) Korean Patent Registration No. 10-2508004 (published on March 9, 2023).

[0009] However, tetrabutylammonium tetrafluoroborate, represented by the following chemical formula 1, still has an unsatisfactory charge capacity, i.e., energy density. Although tetrabutylammonium tetrafluoroborate has a large molecular weight of 329, its storage capacity is limited because it is a monovalent ion. In other words, the charge / molecular weight ratio is only 1 / 329.

[0010] <Chemical Formula 1> (tetrabutylammonium tetrafluoroborate)

[0011]

[0012] To increase the energy density of supercapacitors, the development of new types of electrolytes is essential. Based on the principle of supercapacitors, increasing the charge of the electrolyte increases the energy density of the supercapacitor by a proportional amount. Therefore, a new divalent electrolyte, replacing the existing monovalent electrolyte, is being developed to increase the storage capacity of supercapacitors.

[0013] If a divalent ion electrolyte could be created instead of the existing monovalent ion electrolyte, the energy density of a supercapacitor could be doubled. With this in mind, the present invention developed a new divalent ion electrolyte.

[0014] The electrolyte solution according to the present invention comprises (I) an electrolyte salt (ionic compound) represented by the following chemical formula 2 and (ii) an electrolyte solvent.

[0015] <Chemical Formula 2>

[0016] .

[0017] The content of the electrolyte salt (SBPBF4 salt) represented by the above chemical formula 2 may be included in an amount of 1-99 parts by weight per 100 parts by weight of the electrolyte solution. Preferably, the SBPBF4 salt is 20-50 parts by weight per 100 parts by weight of the electrolyte solution. If the content of the SBPBF4 salt is less than 20 parts by weight, the energy density is low, which is not preferable. If the content of the SBPBF4 salt exceeds 50 parts by weight, the solubility is saturated, which is not preferable.

[0018] The above electrolyte solvent is acetonitrile, glutaronitrile (GN), or a mixture thereof. In addition, various conventional solvents may be used.

[0019] A supercapacitor according to the present invention comprises a positive electrode, a negative electrode, and an electrolyte solution interposed between the positive electrode and the negative electrode. The positive electrode comprises one of activated carbon, graphene, lithium metal oxide, a mixture thereof, or a composite thereof. The negative electrode comprises activated carbon, graphene, one of these, a mixture thereof, or a composite thereof. The electrolyte solution comprises an electrolyte salt and an electrolyte solvent. The electrolyte salt comprises a compound represented by the following chemical formula 2.

[0020] <Chemical Formula 2>

[0021]

[0022] The supercapacitor further includes a separator positioned (i) between the positive electrode and the electrolyte solution, (ii) between the negative electrode and the electrolyte solution, or (iii) between the positive electrode and the electrolyte solution and between the negative electrode and the electrolyte solution.

[0023] According to the present invention, a compound of the following chemical formula 2 is employed as an electrolyte salt (salt, ionic compound).

[0024] <Chemical Formula 2>

[0025] .

[0026] According to the present invention, a novel compound represented by the following chemical formula 2 and having a molecular weight of 404 is provided.

[0027] <Chemical Formula 2>

[0028] .

[0029] The novel compound of Chemical Formula 2 according to the present invention can be synthesized by the following method: (i) a step of reacting 1,2-dichloroethane and triethylamine in an acetonitrile solvent to obtain N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium dichloride; (ii) a step of dissolving the N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium dichloride in methanol to obtain a primary aqueous solution; (iii) a step of adding KOH and a fluorobolic acid aqueous solution to the primary aqueous solution to allow the solution to react to obtain a secondary aqueous solution; (iv) drying the secondary aqueous solution to obtain a primary solid product; (v) adding acetonitrile to the primary solid product to obtain a tertiary aqueous solution; (vi) concentrating the tertiary aqueous solution and then recrystallizing it to obtain a secondary solid product; and (vii) drying the secondary solid product to obtain a novel ionic salt compound represented by the following chemical formula 2.

[0030] The novel compound of Chemical Formula 2 according to the present invention has a high electrostatic capacity (i.e., a high energy density). Therefore, when used as a supercapacitor electrolyte salt, high energy efficiency can be obtained. Specifically, the molecular weight of the novel compound of Chemical Formula 2 is 404, and the charge per molecule is 2. Therefore, the charge / molecular weight ratio is 2 / 404. When converted to the ratio of molecular weights per charge, the conventional compound represented by Chemical Formula 1 is 329, and the novel compound represented by Chemical Formula 2 is 202. That is, compared to the conventional compound, the charge per weight of the novel compound is 1.628 (=329 / 202). Since the energy density of a supercapacitor is proportional to the charge, this means that the energy density of the novel compound represented by Chemical Formula 2 increases by about 1.628 times compared to the conventional compound represented by Chemical Formula 1.

[0031] In addition, the novel compound of chemical formula 2 according to the present invention has thermal stability at high temperatures and under no-load conditions. Since the novel compound of chemical formula 2 according to the present invention maintains electrochemical stability at high temperatures, it has the effect of preventing degradation of high-temperature load performance of a supercapacitor.

[0032] Figure 1 shows an NMR graph of a novel compound according to the present invention.

[0033] In order to increase the electrostatic capacity of an electrolyte salt, the present inventors synthesized a novel compound represented by chemical formula 2 (N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium di tetrafluoroborate). The molecular weight of the novel compound represented by chemical formula 2 is 404, and its NMR graph is shown in Figure 1.

[0034] <Chemical Formula 2>

[0035]

[0036] The novel compound N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium di tetrafluoroborate represented by chemical formula 2 has a molecular weight of 202 per charge, which is approximately 1.62 times smaller than that of the conventional electrolyte salt tetrabutylammonium tetrafluoroborate represented by chemical formula 1, which is 329. Therefore, when the novel compound represented by chemical formula 2 according to the present invention is used as an electrolyte salt of a supercapacitor, the energy density per weight can be increased by approximately 1.62 times compared to the conventional electrolyte salt.

[0037] Example 1 (Synthesis of a novel compound of chemical formula 2)

[0038] As an electrolyte of the present invention, N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium di tetrafluoroborate was prepared by the following method.

[0039] 1,2-Dichloroethane (50g), triethylamine (125g), and acetonitrile (100g) are placed in an autoclave and sealed. After sealing, the temperature of the autoclave is maintained at 140℃ and the reaction is performed at 6.5 atm for 5 hours. Afterwards, nitrogen gas is introduced and the pressure is maintained at 14 atm and the reaction is performed for an additional 5 hours. After the reaction is complete, transparent needle-shaped crystals are formed under 25℃ and 1 atm. The crystals are recrystallized once more in ethanol, and the recrystallized material is filtered and dried to obtain N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium dichloride. Yield: 67%.

[0040] Dissolve 50 g of N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium dichloride in 175 g of methanol, add 30 g of KOH, and stir for about 3 hours. After stirring, add 110 g of a 42% aqueous solution of fluorobolic acid, and stir for about 2 hours. After completion of the reaction, the contents were dried using a rotary evaporator to obtain a white solid.

[0041] Add 300 g of acetonitrile to the obtained white solid and dissolve it. After dissolving, remove the salt impurity through a filter, and concentrate the clear liquid passing through the filter using a rotary evaporator. After removing 200 g of acetonitrile through concentration, recrystallize the concentrated liquid at -50℃ for 48 hours. The produced white crystals were filtered and dried in vacuum to obtain N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium ditetrafluoroborate as a white solid. The yield is 55%, and the NMR measurement values ​​are as follows. The NMR graph is shown in Figure 1.

[0042] 1 H NMR (400 MHz, CDCl3-D6 / TMS): δ = 1.32 (9H, t, CH3), 3.04 (6H, q, CH2)

[0043]

[0044] The following formula 1 shows a synthetic formula according to Example 1.

[0045] Equation 1

[0046]

[0047]

[0048] Example 2 (Preparation of an electrolyte solution containing 1 M of chemical formula 2)

[0049] Acetonitrile (ACN) and glutaronitrile (GN) were mixed in a volume ratio of 9:1, and then 1M of N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium di tetrafluoroborate (N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium di tetrafluoroborate (abbreviated as "SBPBF4" salt) represented by the chemical formula 2 was dissolved to prepare an electrolyte solution of Example 2. Here, the content of the SBPBF4 salt may be included in an amount of 1-99 parts by weight per 100 parts by weight of the electrolyte solution. Preferably, the content of the SBPBF4 salt is 20-50 parts by weight per 100 parts by weight of the electrolyte solution. If the content of the SBPBF4 salt is less than 20 parts by weight, the energy density is low, which is not preferable. If the SBPBF4 salt content exceeds 50 parts by weight, the solubility is saturated, which is not desirable.

Claims

1. An electrolyte solution characterized by comprising (i) an electrolyte salt (salt, ionic compound) represented by the following chemical formula 2 and (ii) an electrolyte solvent: <Chemical Formula 2> 2. In paragraph 1, The content of the electrolyte salt represented by the above chemical formula 2 is 20 to 50 parts by weight per 100 parts by weight of the electrolyte solution. An electrolyte solution characterized by:

3. In paragraph 1, The above electrolyte solvent is acetonitrile, glutaronitrile (GN), or a mixture thereof. An electrolyte solution characterized by:

4. Containing an anode, a cathode, and an electrolyte solution inserted between the anode and the cathode, The above anode comprises any one of carbon, graphene, lithium oxide, or a mixture thereof, or a composite thereof, The above cathode comprises activated carbon, graphene, a mixture thereof, or a composite thereof, The above electrolyte solution includes an electrolyte salt and an electrolyte solvent, The above electrolyte salt comprises a compound of the following chemical formula 2. Supercapacitors featuring: <Chemical Formula 2> 5. In paragraph 4, The above supercapacitor further includes a separator, The separator is positioned (i) between the anode and the electrolyte solution, (ii) between the cathode and the electrolyte solution, or (iii) between the anode and the electrolyte solution and between the cathode and the electrolyte solution. A supercapacitor characterized by .

6. An electrolyte salt (salt, ionic compound) containing a compound of the following chemical formula 2: <Chemical Formula 2> 7. A novel compound represented by the following chemical formula 2: <Chemical Formula 2> . 8.(i) A step of obtaining N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium dichloride by reacting 1,2-dichloroethan and triethylamine in an acetonitrile solvent; (ii) a step of dissolving the N,N,N,N',N',N'-hexaethyl-ethane-1,2-diammonium dichloride in methanol to obtain a primary aqueous solution; (iii) a step of adding KOH and fluorobolic acid aqueous solutions to the first aqueous solution and reacting them to obtain a second aqueous solution; (iv) a step of drying the secondary aqueous solution to obtain a primary solid resultant; (v) a step of adding acetonitrile to the first solid product to obtain a third aqueous solution; (vi) a step of concentrating the above tertiary aqueous solution and then recrystallizing it to obtain a secondary solid product; and (vii) A step of drying the above secondary solid product to obtain a novel ionic salt compound represented by the following chemical formula 2. A method for producing a compound represented by the following chemical formula 2, characterized in that it includes: <Chemical Formula 2> .

Images