Aluminum battery

Abstract

PURPOSE: To provide an aluminum battery having excellent performance in terms of life and / or electric characteristics.SOLUTION: An aluminum battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The electrolyte is impregnated into the separator, the positive electrode, and the negative electrode. The electrolyte includes an aluminum halide, an ionic liquid, and an additive, and the additive includes a pyridine-based compound. The pyridine-based compound has an electron-withdrawing functional group.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an aluminum battery. [Background technology]

[0002] Current aluminum batteries use an electrolyte composed of aluminum chloride and ionic liquid. During the charge / discharge process of an aluminum battery, the negative electrode half-reaction is the electrochemical deposition of aluminum metal. The aluminum metal dendrites generated during this half-reaction tend to grow on the separator and may penetrate the separator and contact the positive electrode, causing electrical conduction between the positive and negative electrodes, resulting in a short circuit in the battery and affecting the life and performance of the aluminum battery. Summary of the Invention [Problem to be solved by the invention]

[0003] The dendritic morphology of aluminum metal produced in the negative electrode half-reaction tends to grow on the separator and may penetrate the separator and contact the positive electrode, causing electrical conduction between the positive and negative electrodes, resulting in a short circuit in the battery and affecting the life and performance of the aluminum battery. [Means for solving the problem]

[0004] The present invention provides an aluminum battery having excellent performance in terms of lifespan and / or electrical characteristics.

[0005] The aluminum battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The electrolyte is impregnated into the separator, the positive electrode, and the negative electrode. The electrolyte includes an aluminum halide, an ionic liquid, and an additive, and the additive includes a pyridine-based compound. The pyridine-based compound has an electron-withdrawing functional group.

[0006] In one embodiment of the present invention, the electron-withdrawing functional group is selected from one of a cyano group (nitrile), an amide group (amide), an acyl chloride group (acyl chloride), a carboxyl group (carboxyl-), and an ester (alkoxycarbonyl-).

[0007] In one embodiment of the present invention, the electron-withdrawing functional group is located at the 2-, 3-, or 4-position of the pyridine-based compound.

[0008] In one embodiment of the present invention, in the above-mentioned electrolytic solution, the weight of the aluminum halide is greater than the weight of the ionic liquid, and the weight of the ionic liquid is greater than the weight of the additive.

[0009] In one embodiment of the present invention, the weight ratio of the additive in the electrolyte is 0.048 wt % or more and 0.16 wt % or less.

[0010] In one embodiment of the present invention, the weight ratio of the aluminum halide in the electrolyte is between 49 wt % and 65 wt %.

[0011] In one embodiment of the present invention, the weight ratio of the ionic liquid in the electrolyte solution is between 35 wt % and 51 wt %.

[0012] In one embodiment of the present invention, the total weight ratio of the aluminum halide, the ionic liquid, and the additive in the electrolyte is 100 wt %.

[0013] In one embodiment of the present invention, the aluminum halide includes aluminum chloride, and the ionic liquid includes 1-ethyl-3-methylimidazolium chloride.

[0014] In one embodiment of the present invention, the above-mentioned negative electrode comprises an aluminum foil, a copper foil, or a nickel foil. [Effects of the Invention]

[0015] As described above, the present invention introduces an electrolyte solution containing a pyridine-based compound with an electron-withdrawing functional group into the design of an aluminum battery, and the electron-withdrawing functional group adjusts the charge state of the nitrogen on the pyridine-based compound to form fine aluminum nuclei, thereby suppressing the formation of aluminum metal dendrites during charging, making it less likely to cause short circuits, and increasing the reaction area during discharging, thereby improving the life and / or electrical properties of the aluminum battery.

[0016] In order to make the above features and advantages of the present invention more clearly understandable, the following embodiments will be described in detail in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the results of surface analysis of Comparative Example 1. [Figure 2] FIG. 1 is a schematic diagram showing the results of surface analysis in Example 1. [Figure 3] FIG. 2 is a schematic diagram showing the results of a life test after assembly into an aluminum battery in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0018] In order to facilitate understanding of the present invention, the following embodiments are provided to illustrate certain examples of how the present invention can be implemented. For clarity, many practical details are included in the following description. However, it should be understood that these practical details are not intended to limit the present invention. That is, in some embodiments of the present invention, these practical details are not required.

[0019] In order to clearly explain the present invention, the description of known aluminum battery design rules is omitted herein, but a person having ordinary skill in the art can design according to actual needs without departing from the spirit and scope of the present invention.

[0020] Unless otherwise defined, all technical terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0021] Unless otherwise stated, the term "between" when used herein to define a numerical range includes values ​​equal to and between the recited endpoints. For example, a dimensional range between a first value and a second value means that the dimensional range can include the first value, the second value, and any value between the first and second values.

[0022] In this embodiment, the aluminum battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, the separator is disposed between the positive electrode and the negative electrode, and the electrolyte is impregnated into the separator, the positive electrode, and the negative electrode. Here, the positive electrode, the negative electrode, the separator, and the electrolyte can be arranged relative to each other in a suitable manner known in the field of aluminum batteries, but the present invention is not limited thereto.

[0023] The electrolyte solution includes an aluminum halide, an ionic liquid, and an additive, the additive including a pyridine-based compound, the pyridine-based compound having an electron-withdrawing functional group. Thus, in this embodiment, an electrolyte solution including a pyridine-based compound with an electron-withdrawing functional group is introduced into the design of an aluminum battery. The electron-withdrawing functional group adjusts the charge state of the nitrogen on the pyridine-based compound to form fine aluminum nuclei. This suppresses the formation of aluminum metal dendrites during charging, making short circuits less likely to occur, and increases the reaction area during discharging, thereby improving the life and / or electrical performance of the aluminum battery. Because the present invention is designed for an aluminum battery, the electrolyte solution uses an aluminum halide and an ionic liquid capable of generating active materials, such as aluminum ions, rather than the electrolyte components selected for other types of batteries.

[0024] More specifically, the additives described above adsorb to the negative electrode during the charging process of an aluminum battery, thereby changing the growth crystal plane of the electrodeposited layer, suppressing the electrodeposition reaction, improving the electrodeposition potential, and affecting the deposition rate of aluminum nuclei. This results in fine aluminum nuclei, thereby enabling a dense, uniform, and highly smooth electrodeposited layer (aluminum metal layer). This prevents the formation of sharp aluminum dendrites, making short circuits less likely to occur and improving the life of the aluminum battery. During the discharging process, the fine aluminum nuclei increase the reaction area, thereby enhancing the reaction capacity, strengthening aluminum dissolution performance, and increasing power capacity.

[0025] In some embodiments, the electron-withdrawing functional group is selected from one of a cyano group, an amide group, an acyl chloride group, a carboxyl group, and an ester, and is located at the 2-, 3-, or 4-position of the pyridine-based compound (e.g., the position shown in Structural Formula 1). For example, the pyridine-based compound may be 4-cyanopyridine. Here, the polarizability of the cyano group at the 4-position is superior to that of other positions, so the pyridine-based compound more easily forms delocalized electrons on the cyano group, increasing the polarizability of the pyridine-based compound. This reduces the electron density of the nitrogen atom on the pyridine, making it more easily adsorbed to the negative electrode. In this way, the electrodeposition potential can be increased, resulting in finer and more uniform electrodeposited aluminum nuclei, but the present invention is not limited thereto.

[0026] [ka]

[0027] In some embodiments, the electrolyte does not include an organic solvent and / or a lithium salt (LiPF, LiBF, LiClO, LiASF), but the present invention is not limited thereto, and the electrolyte may include an organic solvent and / or a lithium salt depending on actual design requirements.

[0028] In some embodiments, the weight of the aluminum halide in the electrolyte is greater than the weight of the ionic liquid, and the weight of the ionic liquid is greater than the weight of the additive, but the present invention is not limited thereto.

[0029] In some embodiments, the weight ratio of the additive in the electrolyte is 0.048 wt% or more and 0.16 wt% or less. If the weight ratio of the additive in the electrolyte exceeds 0.16 wt%, powder will precipitate in the electrolyte, causing turbidity and precipitation. Therefore, better performance can be achieved within the above weight ratio range of the additive, but the present invention is not limited thereto. Here, corresponding to the above weight ratio range, the concentration of the additive in the electrolyte is 20 mM or less, but the present invention is not limited thereto.

[0030] In some embodiments, the weight ratio of aluminum halide in the electrolyte is between 49 wt % and 65 wt %, although the present invention is not limited thereto.

[0031] In some embodiments, the weight ratio of the ionic liquid in the electrolyte solution is between 35 wt % and 51 wt %, although the present invention is not limited thereto.

[0032] In some embodiments, the total weight ratio of the aluminum halide, the ionic liquid, and the additive in the electrolyte is 100 wt %, i.e., the electrolyte is composed of the aluminum halide, the ionic liquid, and the additive containing only a pyridine-based compound.

[0033] In some embodiments, the aluminum halide comprises aluminum chloride (AlCl) and the ionic liquid comprises 1-ethyl-3-methylimidazolium chloride, although the invention is not limited thereto.

[0034] In some embodiments, the additive containing a pyridine-based compound and the aluminum foil, copper foil, or nickel foil may have a synergistic effect, and therefore the negative electrode material more preferably includes aluminum foil, copper foil, or nickel foil, although the present invention is not limited thereto.

[0035] In some embodiments, the thickness of the negative electrode is between 10 micrometers and 100 micrometers, although the invention is not limited thereto.

[0036] In some embodiments, the positive electrode material comprises nickel foil coated with a graphite slurry, although the invention is not limited thereto.

[0037] In some embodiments, the thickness of the positive electrode is between 100 micrometers and 300 micrometers, although the invention is not limited thereto.

[0038] In some embodiments, the separator material comprises fiberglass or other suitable polymeric fibers / films, although the invention is not limited thereto.

[0039] In some embodiments, the thickness of the separator is between 20 micrometers and 500 micrometers, although the invention is not limited thereto.

[0040] The effects that can be achieved by the aluminum battery of the present invention will be explained in more detail below with reference to examples and comparative examples. Although the following examples are described, the details of the materials used and the processes may be appropriately changed without departing from the scope of the present invention, and the present invention should not be interpreted as being limited by the examples described below.

[0041] Example 1

[0042] The electrolyte solution of Example 1 contained aluminum chloride (aluminum halide), 1-ethyl-3-methylimidazolium chloride (ionic liquid), and 4-cyanopyridine (additive), with the molar ratio of aluminum chloride / 1-ethyl-3-methylimidazolium chloride used being 1.8:1, the addition ratio of 4-cyanopyridine being 6 mM, the weight ratio of aluminum chloride in the electrolyte solution being 62.048 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride (EMIC) in the electrolyte solution being 37.904 wt%, and the weight ratio of 4-cyanopyridine in the electrolyte solution being 0.048 wt%.

[0043] <Example 2>

[0044] The electrolyte solution of Example 2 is similar to that of Example 1, but differs in that the addition ratio of 4-cyanopyridine in the electrolyte solution of Example 2 is 10 mM, the weight ratio of aluminum chloride in the electrolyte solution is 62.03 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride (EMIC) in the electrolyte solution is 37.89 wt%, and the weight ratio of 4-cyanopyridine in the electrolyte solution is 0.08 wt%.

[0045] Example 3

[0046] The electrolyte solution of Example 3 is similar to that of Example 1, but differs in that the addition ratio of 4-cyanopyridine in the electrolyte solution of Example 3 is 20 mM, the weight ratio of aluminum chloride in the electrolyte solution is 64.19 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride (EMIC) in the electrolyte solution is 35.65 wt%, and the weight ratio of 4-cyanopyridine in the electrolyte solution is 0.16 wt%.

[0047] <Comparative Example 1>

[0048] The electrolyte solution of Comparative Example 1 is similar to that of Example 1, except that the electrolyte solution of Comparative Example 1 does not contain any additives, the weight ratio of aluminum chloride in the electrolyte solution is 62.1 wt%, and the weight ratio of 1-ethyl-3-methylimidazolium chloride (EMIC) in the electrolyte solution is 37.9 wt%.

[0049] The measurement results are shown in Figures 1 to 3 and Table 1, and the conclusions are as follows: Here, the definition of the power capacity retention rate (%) in Table 1 is the ratio of the discharge capacity value after charge / discharge cycles of the aluminum battery to the discharge capacity value after initial stabilization of the aluminum battery.

[0050] [Table 1]

[0051] Figures 1 and 2 are schematic diagrams showing the results of surface analysis of an example and a comparative example. Figures 1 and 2 are diagrams obtained by performing an electrochemical deposition reaction (copper foil as the negative electrode and aluminum foil as the positive electrode) using the electrolytes of Comparative Example 1 and Example 1, respectively, in a potentiostat (Autolab electrochemical workstation), electrodepositing aluminum metal onto the copper foil at a current density of 6 mA for a deposition time of 30 minutes to obtain an electrodeposited aluminum layer, and then performing surface analysis using an SEM electron microscope.

[0052] As can be seen from the results in Figure 1, the surface formed with the electrolyte of Comparative Example 1 was clearly rough, and the aluminum nuclei were large and non-uniform. Furthermore, as can be seen from the results in Figure 2, the surface formed with the electrolyte of Example 1 was highly smooth, and the electrodeposited layer was denser and more uniform. Furthermore, because the electrodeposited layer was denser, the thickness of the electrodeposited layer was also smaller than that of the electrodeposited layer formed with the electrolyte of Comparative Example 1, demonstrating that both the density and uniformity of the electrodeposited layer were reliably improved.

[0053] As can be seen from the results in Table 1, in Comparative Example 1, the power capacity retention rate was 85% in the first 50 cycles of cyclic charging and discharging, but after 200 cycles, the power capacity retention rate was 46%. In Example 1, the power capacity retention rate was 94% in the first 50 cycles and remained at 76% even after 200 cycles of cyclic charging and discharging. In Example 2, the power capacity retention rate was 100% in the first 50 cycles and remained at 76% even after 200 cycles of cyclic charging and discharging. In Example 3, the power capacity retention rate was 100% in the first 50 cycles and remained at 100% even after 200 cycles of cyclic charging and discharging. As can be seen from these results, the additive can effectively improve electrical performance. As the additive concentration (addition amount) increases, the power capacity retention rate tends to be further improved. This indicates that the aluminum nuclei form finer aluminum layers, increasing the surface area and making the aluminum dissolution reaction more efficient, thereby preventing a decrease in discharge capacity even after multiple cycles of cyclic charging and discharging.

[0054] Fig. 3 is a schematic diagram showing the results of a life test after assembly into an aluminum battery in Examples and Comparative Examples. Here, Fig. 3 shows the results of a power capacity and life test obtained by assembling a coin-type aluminum battery (coin cell) using Examples 1, 2, 3, and Comparative Example 1 as the electrolyte, aluminum foil as the negative electrode, nickel foil coated with graphite paste as the positive electrode, and glass fiber as the separator, and then conducting a charge / discharge test at a charge / discharge rate of 4C using a charge / discharge tester.

[0055] As can be seen from the results in Figure 3, the life performance of the aluminum batteries was 121 cycles on average for the aluminum batteries containing the electrolyte of Comparative Example 1, 184 cycles for the aluminum batteries containing the electrolyte of Example 1, 204 cycles for the aluminum batteries containing the electrolyte of Example 2, and 220 cycles for the aluminum batteries containing the electrolyte of Example 3, demonstrating that the aluminum batteries containing the electrolytes of Examples 1, 2, and 3 achieved a longer life than the aluminum battery containing the electrolyte of Comparative Example 1. In other words, increasing the amount of additive does not adversely affect the life of the aluminum battery, and the smooth electrodeposit layer is less likely to produce sharp dendrites, which makes it less likely to cause a short circuit in the battery, thereby gradually improving life performance.

[0056] As described above, the present invention introduces an electrolyte solution containing a pyridine-based compound with an electron-withdrawing functional group into the design of an aluminum battery, and the electron-withdrawing functional group adjusts the charge state of the nitrogen on the pyridine-based compound to form fine aluminum nuclei, thereby suppressing the formation of aluminum metal dendrites during charging, making it less likely to cause short circuits, and increasing the reaction area during discharging, thereby improving the life and / or electrical properties of the aluminum battery.

[0057] Although the present invention has been disclosed by the above embodiments, these are not intended to limit the present invention, and a person having ordinary knowledge in the art can make some changes and modifications without departing from the spirit and scope of the present invention, and therefore the scope of protection of the present invention shall be defined by the claims below. [Industrial Applicability]

[0058] The aluminum battery can be applied in the aluminum battery field.

Claims

1. A positive electrode and a negative electrode; a separator disposed between the positive electrode and the negative electrode; an electrolyte impregnated in the separator, the positive electrode, and the negative electrode; the electrolyte solution comprises an aluminum halide, an ionic liquid, and an additive, the additive comprises a pyridine-based compound, the pyridine-based compound has an electron-withdrawing functional group, and the electron-withdrawing functional group comprises a cyano group.

2. 2. The aluminum battery according to claim 1, wherein the electron-withdrawing functional group is located at the 2-position, 3-position, or 4-position of the pyridine-based compound.

3. 2. The aluminum battery according to claim 1, wherein, in the electrolyte, the weight of the aluminum halide is greater than the weight of the ionic liquid, and the weight of the ionic liquid is greater than the weight of the additive.

4. 2. The aluminum battery according to claim 1, wherein the weight ratio of the additive in the electrolyte is 0.048 wt % or more and 0.16 wt % or less.

5. 2. The aluminum battery according to claim 1, wherein the weight ratio of the aluminum halide in the electrolyte is between 49 wt % and 65 wt %.

6. 2. The aluminum battery according to claim 1, wherein the weight ratio of the ionic liquid in the electrolyte solution is between 35 wt % and 51 wt %.

7. 2. The aluminum battery according to claim 1, wherein the total weight ratio of the aluminum halide, the ionic liquid, and the additive in the electrolyte is 100 wt %.

8. 2. The aluminum battery according to claim 1, wherein the aluminum halide comprises aluminum chloride and the ionic liquid comprises 1-ethyl-3-methylimidazolium chloride.

9. 2. The aluminum battery according to claim 1, wherein the negative electrode comprises aluminum foil, copper foil, or nickel foil.

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