Aqueous-organic composite electrolyte for zinc ion battery, manufacturing method therefor, and zinc ion battery including same

Abstract

The present invention relates to an aqueous-organic composite electrolyte for a zinc ion battery, a manufacturing method therefor, and a zinc ion battery including same, and, more specifically, the aqueous-organic composite electrolyte of the present invention exhibits flame retardancy in an aqueous electrolyte and can reduce the risk of fire, and thus can improve the safety of a battery. Additionally, the aqueous-organic composite electrolyte of the present invention is applied to a zinc ion battery such that charging / discharging efficiency, lifespan characteristics and rapid charging characteristics can be significantly improved over those of a conventional zinc ion battery.

Description

Aqueous-organic composite electrolyte for zinc-ion batteries, method for producing the same, and zinc-ion batteries containing the same

[0001] The present invention relates to an aqueous-organic composite electrolyte for a zinc-ion battery, a method for producing the same, and a zinc-ion battery including the same.

[0002] With the advent of the carbon-neutral era, global environmental regulations are becoming increasingly stringent, and the eco-friendly secondary battery industry is gaining traction. Lithium-ion batteries, currently the market leader, face safety concerns due to resource shortages and the risk of fire or explosions from flammable organic electrolytes. Therefore, developing low-cost secondary battery manufacturing technology that utilizes abundant, eco-friendly materials and boasts high safety and performance is a key goal for Korea's future secondary battery research.

[0003] From this perspective, there is significant interest in environmentally friendly, low-cost zinc batteries, which utilize abundant zinc as their primary material. However, zinc used as the cathode corrodes in water-based electrolytes, generating hydrogen gas. Furthermore, during charging and discharging, the zinc metal grows into pointed dendrites, forming a passive film that impedes ion penetration, reducing the battery's lifespan and efficiency.

[0004] Recently, solutions have been proposed to address these issues, including the introduction of a protective film that limits direct contact between water and zinc metal, or the introduction of an alloy cathode mixed with other metals. However, the complex manufacturing process and high cost of these methods limit their practical application.

[0005] Additionally, new electrolyte additives and co-solvents that can reduce the reactivity of water are being studied, but they have not reached the level of commercialization due to the problem of reduced safety caused by the addition of flammable organic materials.

[0006] [Prior Art Literature]

[0007] [Patent Document]

[0008] (Patent Document 1) Korean Patent Publication No. 2023-0129894

[0009] In order to solve the above problems, the present invention aims to provide an aqueous-organic composite electrolyte for a zinc-ion battery that exhibits high safety without being combustible and has improved electrochemical stability between the electrode and electrolyte interface.

[0010] In addition, the present invention aims to provide a zinc-ion battery including the aqueous-organic composite electrolyte, which has improved charge / discharge efficiency and enables long life and rapid charging.

[0011] In addition, the present invention aims to provide a device including the zinc ion battery.

[0012] In addition, the present invention aims to provide a method for manufacturing an aqueous-organic composite electrolyte for a zinc ion battery.

[0013] The present invention provides an aqueous-organic composite electrolyte for a zinc-ion battery, comprising: a metal salt containing zinc cations; and a mixed solvent containing water and a cosolvent; wherein the mixed solvent contains 0.01 to 99.99 volume% of water and 0.01 to 99.99 volume% of a cosolvent.

[0014] In addition, the present invention provides a zinc ion battery comprising the aqueous-organic composite electrolyte of the present invention.

[0015] In addition, the present invention provides a device comprising a zinc ion battery of the present invention, wherein the device is any one selected from a communication device, a transportation device, and an energy storage device.

[0016] In addition, the present invention provides a method for producing an aqueous-organic composite electrolyte for a zinc-ion battery, comprising the step of mixing a metal salt containing zinc cations; and a mixed solvent containing water and a cosolvent; wherein the mixed solvent contains 0.01 to 99.99 volume% of water and 0.01 to 99.99 volume% of a cosolvent.

[0017] The aqueous-organic composite electrolyte of the present invention is prepared by adding a cosolvent having flame retardancy to an aqueous electrolyte, and mixing water and the cosolvent at a specific mixing ratio to suppress side reactions such as hydrogen evolution reaction, zinc corrosion, and dendrite growth between the electrode and electrolyte interface, and secure chemical / electrochemical stability.

[0018] Furthermore, since it has excellent flame retardancy, it can reduce the risk of fire that may occur in abnormal situations such as internal short circuit / overcharge / overheating, thereby improving battery safety. Furthermore, by applying the aqueous-organic composite electrolyte of the present invention to a zinc-ion battery, the charge / discharge efficiency, life characteristics, and rapid charging characteristics can be significantly improved compared to existing zinc-ion batteries.

[0019] The effects of the present invention are not limited to those mentioned above. It should be understood that the effects of the present invention encompass all effects inferred from the following description.

[0020] Figure 1 is a schematic diagram of a zinc ion battery including an aqueous-organic composite electrolyte according to the present invention.

[0021] Figure 2 is a photograph showing the results of solubility evaluation of aqueous-organic electrolytes and aqueous electrolytes manufactured in Examples 1 to 4 and Comparative Examples 1 to 4 according to the present invention.

[0022] FIG. 3 is a graph showing the charge / discharge efficiency according to the number of cycles for the Zn||Cu battery of Example 6 manufactured using the aqueous-organic electrolyte and the aqueous electrolyte manufactured in Examples 1 to 4 and Comparative Examples 1 and 2 according to the present invention.

[0023] FIG. 4 is a graph showing the capacity retention rate after 600 cycles for the Zn||CVO battery of Example 7 manufactured using the aqueous-organic composite electrolyte and the aqueous electrolyte manufactured in Examples 1 to 3 and Comparative Example 1 according to the present invention.

[0024] FIG. 5 is a graph showing the capacity retention rate after 400 cycles for the Zn||A-V2O5 / G battery of Example 8 manufactured using the aqueous-organic composite electrolyte and aqueous electrolyte manufactured in Example 4 and Comparative Example 2 according to the present invention.

[0025] Figure 6 is a photograph showing the results of flame retardancy evaluation for a common solvent and the electrolytes of Comparative Examples 1 to 2 and Examples 1 to 4 according to the present invention.

[0026] Hereinafter, the present invention will be described in more detail with one embodiment.

[0027] The present invention relates to an aqueous-organic composite electrolyte for a zinc-ion battery, a method for producing the same, and a zinc-ion battery including the same.

[0028] As previously explained, zinc metal used as the cathode in zinc batteries corrodes in water-based electrolytes, generating hydrogen gas. During charging and discharging, the zinc metal grows into pointed dendritic crystals, forming a passive film that does not allow ions to pass through, which causes problems such as a decrease in the battery's lifespan characteristics and efficiency.

[0029] Accordingly, in the present invention, a cosolvent having flame retardancy is added to an aqueous electrolyte, and by mixing water and the cosolvent at a specific mixing ratio to produce an aqueous-organic composite electrolyte, side reactions such as hydrogen generation reaction, zinc corrosion, and dendrite growth between the electrode and electrolyte interface can be suppressed, and chemical / electrochemical stability can be secured.

[0030] Furthermore, its excellent flame retardancy can reduce the risk of fire that may occur in abnormal situations such as internal short circuits, overcharging, and overheating, thereby enhancing battery safety. Furthermore, by applying the aqueous-organic composite electrolyte of the present invention to a zinc-ion battery, the charge-discharge efficiency, life characteristics, and rapid charging characteristics can be significantly improved compared to existing zinc-ion batteries.

[0031] Specifically, the present invention provides an aqueous-organic composite electrolyte for a zinc-ion battery, comprising: a metal salt containing zinc cations; and a mixed solvent containing water and a cosolvent; wherein the mixed solvent contains 0.01 to 99.99 volume% of water and 0.01 to 99.99 volume% of a cosolvent.

[0032] The above metal salt is Zn 2+ , CF3SO3 - , Cl - , Br - , I - , CH3COO - , NO3 - , BF4 - , ClO4 - , SO4 2- , FSI - , PF6 - and TFSI - It may include one type of anion selected from the group consisting of .

[0033] Preferably, the metal salt may be at least one selected from the group consisting of Zn(CF3SO3)2, Zn(CH3COO)2, ZnSO4, ZnCl2, Zn(ClO4)2, and Zn(TFSI)2, more preferably at least one selected from the group consisting of Zn(CF3SO3)2, ZnCl2, Zn(ClO4)2, and Zn(TFSI)2, and most preferably, the metal salt may be Zn(CF3SO3)2 (hereinafter referred to as Zn(OTf)2).

[0034] The molar concentration of the metal salt in the above aqueous-organic composite electrolyte may be 0.1 to 20 m, preferably 1 to 6 m, more preferably 1 to 3 m, and most preferably 2 to 3 m. In particular, if the molar concentration of the metal salt is less than 0.1 m, the ionic conductivity of the electrolyte may be low due to the low zinc ion concentration in the electrolyte, which may result in poor performance of the zinc ion battery. Conversely, if it exceeds 20 m, the metal salt may not be sufficiently dissolved in the electrolyte.

[0035] Among the above mixed solvents, the cosolvent can play a role in suppressing the hydrogen evolution reaction occurring at the zinc anode, zinc corrosion, and the formation of a passive film at the anode interface by strongly interacting with water, thereby reducing the reactivity of water. Furthermore, it promotes the decomposition of anions, thereby forming an inorganic-based, highly stable electrode-electrolyte interface, thereby improving the problems of anode / cathode irreversibility and low coulombic efficiency of existing zinc-ion batteries. Furthermore, the cosolvent has the advantage of being flame retardant, thus not compromising the safety of the water-based electrolyte.

[0036] The above mixed solvent may contain 0.01 to 99.99 volume% of water and 0.01 to 99.99 volume% of co-solvent, preferably 10 to 90 volume% of water and 10 to 90 volume% of co-solvent, more preferably 50 to 70 volume% of water and 30 to 50 volume% of co-solvent, and most preferably 50 to 60 volume% of water and 40 to 50 volume% of co-solvent.

[0037] In particular, if the content of the cosolvent is less than 0.01% by volume, a hydrogen generation reaction may occur between the interface of the electrode and the electrolyte, and side reactions such as zinc corrosion and dendrite growth may occur, which may significantly reduce the charge / discharge efficiency and life characteristics of the zinc-ion battery. On the other hand, if the content of the cosolvent exceeds 99.99% by volume, the overvoltage of the battery may increase due to the excessive addition of the cosolvent, which may lead to a decrease in the performance of the battery.

[0038] Specific examples of the above co-solvents include N,N-diethyl-2,3,3,3-tetrafluoropropionamide, N,N-diethyl-2,2,2-trifluoroacetamide, 2,2-difluoro-N,N-dimethylacetamide, pentafluoropropionamide, fluoroacetamide, 2-fluoro-N,N-dimethylacetamide, 2,2,2-trifluoroacetamide, N-methyltrifluoroacetamide, and It may be at least one selected from the group consisting of N,N-dimethyltrifluoroacetamide, preferably N,N-diethyl-2,3,3,3-tetrafluoropropionamide, N,N-diethyl-2,2,2-trifluoroacetamide, or a mixture thereof, and most preferably N,N-diethyl-2,3,3,3-tetrafluoropropionamide.

[0039] In particular, when N,N-diethyl-2,3,3,3-tetrafluoropropionamide is used as the above-mentioned co-solvent, it has an abundance of fluorine functional groups compared to other co-solvents, so that a stable SEI layer (Solid Electrolyte Interphase) can be formed at the electrode-electrolyte interface.

[0040] Preferably, the aqueous-organic composite electrolyte may have a molar concentration of the metal salt in the aqueous-organic composite electrolyte of 1 to 3 m, and the mixed solvent may include 50 to 70 volume% of water and 30 to 50 volume% of a cosolvent. If any one of the molar concentration range of the metal salt and the mixing ratio conditions of water and cosolvent in the mixed solvent is not satisfied, although not explicitly described in the following examples or comparative examples, the metal salt may not sufficiently dissolve in the mixed solvent or may interfere with the desorption and insertion of zinc cations, which may significantly deteriorate the charge / discharge efficiency and life characteristics of the battery.

[0041] In addition, in the aqueous-organic composite electrolyte according to the present invention, the metal salt is Zn(CF3SO3)2, the molal concentration of the metal salt in the aqueous-organic composite electrolyte is 2 to 3 m, the mixed solvent contains 50 to 60 volume% of water and 40 to 50 volume% of a cosolvent, and when the cosolvent is N,N-diethyl-2,3,3,3-tetrafluoropropionamide, unlike the case where any one of these conditions is not satisfied, unlike the zinc-ion battery using the existing aqueous electrolyte, the reversible ion deposition / desorption or insertion / desorption at the electrolyte and electrode interface is actively performed, so that the rapid charging characteristics are remarkably excellent, the durability of the battery is greatly improved, and the effect of securing excellent chemical / electrochemical stability by suppressing the elution of active materials and the formation of side reactions occurring at the positive electrode during charge and discharge is improved, It is particularly desirable to simultaneously satisfy the above conditions, as it also realizes heterogeneous electrochemical properties such as an optimal interfacial heterogeneity index and a reduced zinc deposition overpotential compared to a homogeneous electrolyte.

[0042] In addition, the present invention provides a zinc ion battery comprising the aqueous-organic composite electrolyte of the present invention.

[0043] The above zinc ion battery may include a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an aqueous-organic composite electrolyte of the present invention interposed between the positive electrode and the negative electrode.

[0044] In addition, the zinc ion battery may include a positive electrode including a positive electrode active material; a negative electrode current collector; and an aqueous-organic composite electrolyte of the present invention interposed between the positive electrode and the negative electrode current collector.

[0045] Figure 1 is a schematic diagram of a zinc ion battery including an aqueous-organic composite electrolyte according to the present invention. Referring to Figure 1, a cross-section of a zinc ion battery comprising a positive electrode current collector, a positive electrode formed on the positive electrode current collector, an anode current collector, a negative electrode formed on the negative electrode current collector, and an aqueous-organic composite electrolyte interposed between the positive electrode and the negative electrode can be confirmed. At the interface between the positive electrode and the aqueous-organic composite electrolyte, zinc cations (Zn 2+ ) can be reversibly desorbed and inserted, thereby suppressing the formation of a passive film formed at the anode interface. In addition, a stable SEI layer is formed at the interface between the cathode and the aqueous-organic composite electrolyte, showing high zinc deposition and desorption reversibility and suppressing the hydrogen evolution reaction and zinc corrosion at the cathode.

[0046] The above positive electrode can be manufactured by mixing a positive electrode active material, a binder, and a conductive material in a process solvent to manufacture a positive electrode slurry, coating the positive electrode slurry on a positive electrode current collector, and then drying and rolling.

[0047] The above positive electrode may be any one selected from manganese or vanadium-based oxides, Prussian blue-based materials, spinel-structured oxides, organic materials and chevron-like composites, halogen materials, and sulfur-based materials. For example, it may be MnO2, Mn2O3, Mn3O4, V2O5, VO2, rGO / VO2, I2, etc., but the scope of the present invention is not limited thereto, and any positive electrode material that can be commonly applied to a zinc-ion battery can be applied without limitation.

[0048] The positive electrode current collector may be made of aluminum, stainless steel, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and is not particularly limited thereto as long as it has conductivity and does not cause chemical changes in the battery.

[0049] The above negative electrode may be a zinc metal foil, a zinc metal powder, or an alloy with another metal, or, similarly to the positive electrode, may be manufactured by mixing a negative electrode active material, a binder, and a conductive material in a solvent to manufacture a negative electrode slurry, coating the negative electrode slurry on a negative electrode current collector, and then drying and rolling.

[0050] However, the scope of the present invention is not limited thereto, and all commonly applied cathode materials, such as various protective layers that can prevent corrosion of zinc metal, can be applied.

[0051] The above negative electrode current collector may be at least one selected from the group consisting of copper (Cu), titanium (Ti), and stainless steel (SUS), but is not limited thereto.

[0052] The above zinc ion battery may further include a separator disposed between the positive electrode and the negative electrode.

[0053] The above separator may be at least one selected from the group consisting of glass fiber, silicon oxide, polyethylene, and polypropylene, and preferably may be glass fiber.

[0054] In addition, the present invention provides a device comprising a zinc ion battery of the present invention, wherein the device is any one selected from a communication device, a transportation device, and an energy storage device.

[0055] In addition, the present invention provides a method for producing an aqueous-organic composite electrolyte for a zinc-ion battery, comprising the step of mixing a metal salt containing zinc cations; and a mixed solvent containing water and a cosolvent; wherein the mixed solvent contains 0.01 to 99.99 volume% of water and 0.01 to 99.99 volume% of a cosolvent.

[0056] The above metal salt is Zn 2+ , CF3SO3 - , Cl - , Br - , I - , CH3COO - , NO3 - , BF4 - , ClO4 - , SO4 2- , FSI - , PF6 - and TFSI - It may include one kind of anion selected from the group consisting of. Preferably, the metal salt may be at least one kind selected from the group consisting of Zn(CF3SO3)2, Zn(CH3COO)2, ZnSO4, ZnCl2, Zn(ClO4)2 and Zn(TFSI)2, more preferably, it may be at least one kind selected from the group consisting of Zn(CF3SO3)2, ZnCl2, Zn(ClO4)2 and Zn(TFSI)2, and most preferably, the metal salt may be Zn(CF3SO3)2 (hereinafter referred to as Zn(OTf)2).

[0057] In addition, metal salts containing cations other than zinc, such as lithium salts, magnesium salts, sodium salts, aluminum salts, and calcium salts, may be optionally included, and the electrolyte may also optionally further include additives for improving the electrochemical properties of the electrolyte, including film-forming additives (saccharin, trimethylethylammonium trifluoromethanesulfonate (Me3EtNOTF), KPF6, etc.), surface adsorption additives (1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM]OTF), 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMImOTf), CeCl3, etc.) and organic solvent additives (dimethyl sulfoxide, ethylene glycol, Succinonitrile, etc.), and the electrolyte composition of the present invention is not limited thereto, and an electrolyte including all solvents, salts, additives, and other components that are typically applicable to a zinc ion battery may be applied without limitation.

[0058] The molar concentration of the metal salt in the above aqueous-organic composite electrolyte may be 0.1 to 20 m, preferably 1 to 6 m, more preferably 1 to 3 m, and most preferably 2 to 3 m.

[0059] The above mixed solvent may contain 0.01 to 99.99 volume% of water and 0.01 to 99.99 volume% of co-solvent, preferably 10 to 90 volume% of water and 10 to 90 volume% of co-solvent, more preferably 50 to 70 volume% of water and 30 to 50 volume% of co-solvent, and most preferably 50 to 60 volume% of water and 40 to 50 volume% of co-solvent.

[0060] Specific examples of the above co-solvents include N,N-diethyl-2,3,3,3-tetrafluoropropionamide, N,N-diethyl-2,2,2-trifluoroacetamide, 2,2-difluoro-N,N-dimethylacetamide, pentafluoropropionamide, fluoroacetamide, 2-fluoro-N,N-dimethylacetamide, 2,2,2-trifluoroacetamide, N-methyltrifluoroacetamide, and It may be at least one selected from the group consisting of N,N-dimethyltrifluoroacetamide, preferably N,N-diethyl-2,3,3,3-tetrafluoropropionamide, N,N-diethyl-2,2,2-trifluoroacetamide, or a mixture thereof, and most preferably N,N-diethyl-2,3,3,3-tetrafluoropropionamide.

[0061] Preferably, the aqueous-organic composite electrolyte has a molar concentration of the metal salt in the aqueous-organic composite electrolyte of 1 to 3 m, and the mixed solvent may include 50 to 70 volume% of water and 30 to 50 volume% of a cosolvent.

[0062] More preferably, the aqueous-organic composite electrolyte has a metal salt of Zn(CF3SO3)2, a molar concentration of the metal salt in the aqueous-organic composite electrolyte of 2 to 3 m, and the mixed solvent contains 50 to 60 volume% of water and 40 to 50 volume% of a cosolvent, and the cosolvent may be N,N-diethyl-2,3,3,3-tetrafluoropropionamide.

[0063] In this way, the aqueous-organic composite electrolyte of the present invention adds a cosolvent having flame retardancy, and mixes water and the cosolvent at a specific mixing ratio, thereby securing excellent electrochemical stability between the electrode and electrolyte interface, thereby significantly improving the charge / discharge efficiency of a zinc-ion battery and enabling the implementation of a battery with a long life and rapid charging.

[0064] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[0065] Example

[0066] Examples 1 to 5 and Comparative Examples 1 to 4: Aqueous-organic composite electrolytes and aqueous electrolytes

[0067] Aqueous-organic composite electrolytes were prepared by mixing zinc trifluoromethanesulfonate (Zn(OTf)2) salt at a 2 molal or 3 molal concentration or zinc di bis(trifluoromethylsulfonyl)imide (Zn(TFSI)2) salt at a 2 molal concentration with water and N,N-diethyl-2,3,3,3-tetrafluoropropionamide as a cosolvent at various volume ratios as shown in Table 1 below.

[0068]

[0069] Manufacturing Example 1: Manufacturing of CVO anode

[0070] CaV6O as a cathode active material 16· A positive electrode mixture slurry was prepared by adding 70 wt%, 20 wt%, and 10 wt% of 3H2O (CVO), carbon black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder to N-methyl-2-pyrrolidone (NMP) as a solvent. The positive electrode mixture slurry was applied to a stainless steel (SUS304) thin film as a positive electrode current collector with a thickness of 20 ㎛, dried, and then rolled (rolling rate 20%) using a roll press.

[0071] Manufacturing Example 2: A-V2O5 / G anode

[0072] Amorphous V2O5 grown on graphene as a cathode active material (A-V2O5 / G), carbon black as a conductive material, and PVdF as a binder were added to NMP as a solvent at 70 wt%, 20 wt%, and 10 wt%, respectively, to prepare a cathode mixture slurry. The cathode mixture slurry was applied to a titanium (Ti) thin film as a cathode current collector with a thickness of 35 μm, dried, and then rolled (rolling rate 20%) using a roll press.

[0073] Example 6: Fabrication of Zn||Cu batteries

[0074] A copper (Cu) thin film with a thickness of 20 ㎛, a glass fiber separator, and a zinc (Zn) metal cathode with a thickness of 250 ㎛ were laminated and assembled, and then the electrolytes of Comparative Examples 1 and 2 and Examples 1 to 4 were injected into the separator, respectively, to manufacture a Zn||Cu battery.

[0075] Example 7: Fabrication of Zn||CVO batteries

[0076] After the CVO positive electrode, glass fiber separator, and zinc (Zn) metal negative electrode having a thickness of 250 μm manufactured in the above Manufacturing Example 1 were laminated and assembled, the electrolytes of Comparative Example 1 and Examples 1 to 3 were injected into the separator to manufacture a Zn||CVO battery.

[0077] Example 8: Fabrication of Zn||A-V2O5 / G battery

[0078] The A-V2O5 / G positive electrode, glass fiber separator, and zinc (Zn) metal negative electrode having a thickness of 22250 ㎛ manufactured in the above Manufacturing Example 2 were laminated and assembled, and then the electrolytes of Comparative Example 2 and Example 4 were injected into the separator to manufacture a Zn||A-V2O5 / G battery.

[0079] Experimental Example 1: Solubility Evaluation

[0080] The solubility of the aqueous-organic electrolytes and aqueous electrolytes prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was confirmed, and the results are shown in Fig. 2.

[0081] Figure 2 is a photograph showing the results of solubility evaluation of the aqueous-organic electrolytes and aqueous electrolytes manufactured in Examples 1 to 4 and Comparative Examples 1 to 4. Referring to Figure 2, it was confirmed that the electrolytes of Examples 1 to 4 and Comparative Examples 1 and 2 had completely dissolved metal salts, whereas the electrolytes of Comparative Examples 3 and 4 had not completely dissolved metal salts, making them unsuitable for use as electrolytes.

[0082] Experimental Example 2: Evaluation of Charge / Discharge Efficiency of Zn||Cu Battery

[0083] The electrolytes of Comparative Examples 1 and 2 and Examples 1 to 5 were applied to a Zn||Cu battery to obtain a current of 1 mA / cm 2 After discharging at a current density of , charging to 0.4 V at the same current density was considered one cycle, and the coulombic efficiency was evaluated by repeating the cycle. The results are shown in Fig. 3 and Table 2.

[0084] The Coulombic efficiency for each cycle was calculated by multiplying the ratio of desorbed zinc to deposited zinc by 100. If an internal short circuit occurred before 350 cycles, the Coulombic efficiency for each cycle was calculated up to the cycle preceding the cycle in which the internal short circuit occurred, and if no internal short circuit occurred up to 350 cycles, the average Coulombic efficiency was calculated by dividing the sum of the Coulombic efficiency values ​​for all cycles by the number of cycles.

[0085] Figure 3 is a graph showing the charge / discharge efficiency according to the number of cycles for the Zn||Cu battery of Example 6 manufactured using the aqueous-organic electrolytes and aqueous electrolytes manufactured in Examples 1 to 5 and Comparative Examples 1 and 2.

[0086] Table 2 below shows the number of cycles in which internal short circuits occurred and the average coulombic efficiency values ​​in the Zn||Cu batteries of Comparative Examples 1 and 2 and Examples 1 to 5.

[0087] Internal short circuit occurrence cycle average coulomb efficiency Comparison example 135 cycles 96.8% Comparison example 210 cycles 92.5% Example 1 Internal short circuit does not occur 98.1% Example 2 Internal short circuit does not occur 98.2% Example 3 Internal short circuit does not occur 99.1% Example 4 Internal short circuit does not occur 99.2% Example 5 117 cycles 98.2%

[0088] Referring to the above Figure 3 and Table 2, in the case of Examples 1 to 5, it was confirmed that by using an aqueous-organic composite electrolyte including water and a cosolvent, side reactions between the zinc negative electrode and the electrolyte could be suppressed, and thus the coulombic efficiency of the battery was very excellent at 98% or more.

[0089] On the other hand, in the case of Comparative Examples 1 and 2, when the zinc anode and the electrolyte met, side reactions such as hydrogen generation reaction, zinc corrosion, and dendrite growth occurred, which lowered the reversibility of the zinc anode, and as a result, the coulombic efficiency of the battery decreased significantly.

[0090] Experimental Example 3: Performance Evaluation of Zn||CVO Battery

[0091] The electrolytes of Comparative Example 1 and Examples 1 to 3 were applied to Zn||CVO batteries, and charge and discharge were performed in the voltage range of 0.2 V to 1.6 V at a current density of 0.3 A / g. Thereafter, the number of cycles at which internal short circuits occurred in each Zn||CVO battery and the capacity retention rate after 600 cycles were evaluated. The capacity retention rate was calculated by dividing the discharge capacity after 600 cycles by the discharge capacity after the first cycle and multiplying by 100. The results are shown in Fig. 4 and Table 3.

[0092] FIG. 4 is a graph showing the capacity retention rate after 600 cycles for the Zn||CVO battery of Example 7 manufactured using the aqueous-organic composite electrolyte and aqueous electrolyte manufactured in Examples 1 to 3 and Comparative Example 1.

[0093] Table 3 below shows the number of cycles in which internal short circuits occurred in Zn||CVO batteries by electrolyte and the capacity retention rate after 600 cycles.

[0094] Internal short circuit occurrence cycle capacity maintenance rate comparison example 1328 cycle measurement not possible Example 1 Internal short circuit did not occur 81.8% Example 2 Internal short circuit did not occur 94.9% Example 3 Internal short circuit did not occur 97.4%

[0095] According to the results of the above-described Figure 4 and Table 3, in the cases of Examples 1 to 3, no internal short circuit occurred at all, and the capacity retention rate of the battery was maintained at a similar level for 600 cycles. In particular, it was confirmed that the capacity retention rate was maintained at a higher level as the mixing ratio of the co-solvent increased.

[0096] On the other hand, in the case of Comparative Example 1, it was confirmed that an internal short circuit occurred at cycle 328 as zinc grew into dendrites during the battery charging process. In addition, a rapid decrease in battery capacity occurred due to the electrolyte decomposing on the surface of the zinc anode to generate hydrogen, or due to corrosion of the zinc anode or the formation of a passivation film.

[0097] Experimental Example 4: Capacity Retention Evaluation of Zn||A-V2O5 / G Battery

[0098] The electrolytes of Comparative Example 2 and Example 4 were applied to Zn||A-V2O5 / G batteries, and charge and discharge were performed in the voltage range of 0.2 V to 1.8 V at a current density of 2 A / g. Thereafter, the capacity retention rate of each Zn||A-V2O5 / G battery after 400 cycles was evaluated. The capacity retention rate was calculated by dividing the discharge capacity after 400 cycles 2 by the discharge capacity after the first cycle and then multiplying by 100. The results are shown in Fig. 5.

[0099] FIG. 5 is a graph showing the capacity retention rate after 400 cycles for the Zn||A-V2O5 / G battery of Example 8 manufactured using the aqueous-organic composite electrolyte and aqueous electrolyte manufactured in Example 4 and Comparative Example 2.

[0100] Table 4 below shows the capacity retention rate after 400 cycles of Zn||A-V2O5 / G batteries by electrolyte.

[0101] Comparison of capacity retention rates: Example 229.4%, Example 491.8%

[0102] According to the results of the above Figure 5 and Table 4, in the case of the above Example 4, the capacity retention rate was excellently maintained at 91.8% after 400 cycles, whereas in the case of the above Comparative Example 2, the zinc anode was corroded or a passivation film was formed, resulting in a decrease in the capacity of the battery, and the capacity retention rate after 400 cycles was a significantly low figure of 29.4%.

[0103] Experimental Example 5: Evaluation of Electrolyte Flame Retardancy

[0104] To evaluate the thermal stability of the electrolyte, 1 mL each of the cosolvent alone, the electrolyte samples of Comparative Examples 1 to 2, and Examples 1 to 4 were injected into a glass petri dish, ignited using a torch for 30 seconds, and the ignition of the electrolyte was confirmed to evaluate the flame retardancy of the electrolyte. The results are shown in Fig. 6 and Table 5 below.

[0105] Figure 6 is a photograph showing the results of flame retardancy evaluation for the common solvent and the electrolytes of Comparative Examples 1 to 2 and Examples 1 to 4.

[0106] Table 5 below shows the results of flame retardancy evaluation of the co-solvent and each electrolyte.

[0107] Classification Flame retardancy Classification Common solvent Flame retardancy Comparative example 1 Flame retardancy Comparative example 2 Flame retardancy Example 1 Flame retardancy Example 2 Flame retardancy Example 3 Flame retardancy Example 4 Flame retardancy

[0108] According to the results of the above-described Figure 6 and Table 5, each of the aqueous-organic composite electrolytes manufactured in Examples 1 to 4 and Comparative Examples 1 and 2 exhibited flame retardancy. This confirmed that the safety of the battery was excellent, as the risk of fire that could occur in abnormal situations such as internal short circuit, overcharging, and overheating could be reduced.

Claims

1. Metal salt containing zinc cations; and A mixed solvent comprising water and a co-solvent; an aqueous-organic composite electrolyte for a zinc ion battery, An aqueous-organic composite electrolyte for a zinc ion battery, wherein the mixed solvent comprises 0.01 to 99.99 volume% of the water and 0.01 to 99.99 volume% of the cosolvent.

2. In the first paragraph, the metal salt is a zinc cation (Zn 2+ ) and CF3SO3 - , Cl - , Br - , I - , CH3COO - , NO3 - , BF4 - , ClO4 - , SO4 2- , FSI - , PF6 - and TFSI - An aqueous-organic composite electrolyte for a zinc ion battery comprising one anion selected from the group consisting of:

3. An aqueous-organic composite electrolyte for a zinc ion battery, wherein the molal concentration of the metal salt in the aqueous-organic composite electrolyte in the first paragraph is 0.1 to 20 m.

4. An aqueous-organic composite electrolyte for a zinc-ion battery, wherein the mixed solvent comprises 50 to 70 volume% of the water and 30 to 50 volume% of the cosolvent in the first paragraph.

5. In the first paragraph, the co-solvent is N,N-diethyl-2,3,3,3-tetrafluoropropionamide, N,N-diethyl-2,2,2-trifluoroacetamide, 2,2-difluoro-N,N-dimethylacetamide, pentafluoropropionamide, fluoroacetamide, 2-fluoro-N,N-dimethylacetamide, 2,2,2-trifluoroacetamide, N-methyltrifluoroacetamide, and An aqueous-organic composite electrolyte for a zinc ion battery, comprising at least one selected from the group consisting of N,N-dimethyltrifluoroacetamide.

6. In the first paragraph, the molal concentration of the metal salt in the aqueous-organic composite electrolyte is 1 to 3 m, An aqueous-organic composite electrolyte for a zinc ion battery, wherein the mixed solvent comprises 50 to 70 volume% of the water and 30 to 50 volume% of the cosolvent.

7. In paragraph 6, the metal salt is Zn(CF3SO3)2, The molal concentration of the metal salt in the above aqueous-organic composite electrolyte is 2 to 3 m, The above mixed solvent comprises 50 to 60 volume% of the water and 40 to 50 volume% of the cosolvent, An aqueous-organic composite electrolyte for a zinc-ion battery, wherein the above-mentioned common solvent is N,N-diethyl-2,3,3,3-tetrafluoropropionamide.

8. In the first paragraph, the aqueous-organic composite electrolyte for the zinc ion battery additionally includes at least one selected from among lithium salts, magnesium salts, sodium salts, aluminum salts, and calcium salts. The aqueous-organic composite electrolyte for a zinc-ion battery further comprises at least one additive selected from a film-forming additive, a surface adsorption additive, and an organic solvent additive.

9. A zinc-ion battery comprising an aqueous-organic composite electrolyte selected from any one of claims 1 to 8.

10. In the 9th paragraph, the zinc ion battery includes a positive electrode and a negative electrode, The above anode is any one material selected from manganese or vanadium-based oxides, Prussian blue-based materials, spinel-structured oxides, organic materials and chevron-like complexes, halogen materials, and sulfur-based materials. A zinc ion battery wherein the above negative electrode is a zinc metal foil or zinc metal powder or an alloy thereof.

11. A device comprising a zinc ion battery of paragraph 9, wherein the device is any one selected from a communication device, a transportation device, and an energy storage device.

12. A method for producing an aqueous-organic composite electrolyte for a zinc ion battery, comprising the steps of mixing a metal salt containing zinc cations; and a mixed solvent containing water and a cosolvent; A method for producing an aqueous-organic composite electrolyte for a zinc ion battery, wherein the mixed solvent comprises 0.01 to 99.99 volume% of the water and 0.01 to 99.99 volume% of the cosolvent.

13. In the 12th paragraph, the metal salt is a zinc cation (Zn 2+ ) and CF3SO3 - , Cl - , Br - , I - , CH3COO - , NO3 - , BF4 - , ClO4 - , SO4 2- , FSI - , PF6 - and TFSI - A method for producing an aqueous-organic composite electrolyte for a zinc ion battery, the electrolyte comprising one anion selected from the group consisting of:

14. A method for producing an aqueous-organic composite electrolyte for a zinc ion battery, wherein the molal concentration of the metal salt in the aqueous-organic composite electrolyte in the 12th paragraph is 0.1 to 20 m.

15. A method for producing an aqueous-organic composite electrolyte for a zinc-ion battery, wherein the mixed solvent comprises 50 to 70 volume% of the water and 30 to 50 volume% of the cosolvent in the 12th paragraph.

16. In the 12th paragraph, the co-solvent is N,N-diethyl-2,3,3,3-tetrafluoropropionamide, N-diethyl-2,2,2-trifluoroacetamide, 2,2-difluoro-N,N-dimethylacetamide, pentafluoropropionamide, 2 fluoroacetamide, 2-fluoro-N,N-dimethylacetamide, 2,2,2-trifluoroacetamide, N-methyltrifluoroacetamide and A method for producing an aqueous-organic composite electrolyte for a zinc ion battery, the electrolyte comprising at least one selected from the group consisting of N,N-dimethyltrifluoroacetamide.

17. In the 12th paragraph, the molal concentration of the metal salt in the aqueous-organic composite electrolyte is 1 to 3 m, A method for producing an aqueous-organic composite electrolyte for a zinc ion battery, wherein the mixed solvent comprises 50 to 70 volume% of the water and 30 to 50 volume% of the cosolvent.

18. In paragraph 12, the metal salt is Zn(CF3SO3)2, The molal concentration of the metal salt in the above aqueous-organic composite electrolyte is 2 to 3 m, The above mixed solvent contains 50 to 60 volume% of water and 40 to 50 volume% of co-solvent, A method for producing an aqueous-organic composite electrolyte for a zinc ion battery, wherein the above-mentioned co-solvent is N,N-diethyl-2,3,3,3-tetrafluoropropionamide.

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