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 Art

[0002] In the current aluminum battery, the electrolyte is composed of aluminum chloride and an ionic liquid. In the charge and discharge process of the aluminum battery, the negative electrode half-reaction is the electrochemical deposition of aluminum metal. The dendrite form of the aluminum metal generated in this half-reaction is likely to grow on the separator and may penetrate the separator to contact the positive electrode. Therefore, the conduction between the positive and negative electrodes causes a short circuit of the battery, affecting the life and performance of the aluminum battery.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The dendrite form of the aluminum metal generated in the negative electrode half-reaction is likely to grow on the separator and may penetrate the separator to contact the positive electrode. Therefore, the conduction between the positive and negative electrodes causes a short circuit of the battery, affecting the life and performance of the aluminum battery.

Means for Solving the Problems

[0004] The present invention provides an aluminum battery having excellent performance in terms of life 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 installed between the positive electrode and the negative electrode. The electrolyte is impregnated in the separator, the positive electrode, and the negative electrode. The electrolyte includes 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 above-described electron-withdrawing functional group is selected from among a nitrile group, an amide group, an acyl chloride group, a carboxyl group, and alkoxycarbonyls.

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

[0008] In one embodiment of the present invention, in the above-described electrolytic solution, the weight of 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 above-described additive in the electrolytic solution 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 above-described aluminum halide in the electrolytic solution is between 49 wt% and 65 wt%.

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

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

[0013] In one embodiment of the present invention, the above-described 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-described negative electrode includes an aluminum foil, a copper foil, or a nickel foil.

Advantages of the Invention

[0015] As described above, the present invention introduces an electrolyte containing a pyridine-based compound having an electron-withdrawing functional group into the design of an aluminum battery, and adjusts the charged state of nitrogen on the pyridine-based compound by the electron-withdrawing functional group to form fine aluminum nuclei. In this way, the generation of the dendrite form of aluminum metal during the charging process can be suppressed, making it difficult to cause a short circuit, and the reaction area can be increased during the discharging process. Therefore, the aluminum battery can have excellent performance in terms of its lifespan and / or electrical characteristics.

[0016] In order to more clearly understand the above-mentioned features and advantages of the present invention, embodiments will be given below and described in detail in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0018] In order to more easily understand the content of the present invention, embodiments will be given below to show that the present invention is an example that can be surely implemented. For clear explanation, many practical details are also explained in the following description. However, it should be understood that these practical details are not for limiting the present invention. That is, in some embodiments of the present invention, these practical details are not essential.

[0019] To clearly explain the present invention, the description of known aluminum battery design rules is omitted in the text. However, those with ordinary knowledge in the relevant technical field 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 in the text have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0021] Unless otherwise explained, the term "between" used to define a numerical range in this specification includes values equal to the recited endpoint values and the range between the recited endpoint values. For example, when a dimensional range is between a first numerical value and a second numerical value, it means that the dimensional range may include the first numerical value, the second numerical value, and any value between the first numerical value and the second numerical value.

[0022] In this embodiment, the aluminum battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is installed 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 with each other in a suitable manner well-known in the field of aluminum batteries, but the present invention is not limited thereto.

[0023] In addition, the electrolytic solution contains aluminum halide, an ionic liquid, and an additive. The additive contains a pyridine-based compound, and the pyridine-based compound has an electron-withdrawing functional group. Thus, in this embodiment, an electrolytic solution containing a pyridine-based compound having an electron-withdrawing functional group is introduced into the design of an aluminum battery. The electron-withdrawing functional group adjusts the charged state of nitrogen on the pyridine-based compound to form fine aluminum nuclei. In this way, the generation of the dendrite form of aluminum metal during the charging process can be suppressed, making it difficult to cause a short circuit, and the reaction area can be increased during the discharging process. Therefore, the aluminum battery can have excellent performance in terms of its lifespan and / or electrical characteristics. Since the present invention is related to the design of an aluminum battery, the substances used in the electrolytic solution are aluminum halide and an ionic liquid that can generate active substances such as aluminum ions, rather than the electrolytic solution components selected for other types of batteries.

[0024] Furthermore, to elaborate, the aforementioned additive adsorbs to the negative electrode during the charging process of the aluminum battery, so it can change the growth crystal plane of the electrodeposited layer, suppress the electrodeposition reaction, improve the electrodeposition potential, and affect the precipitation rate of aluminum nuclei. Therefore, fine aluminum nuclei can be obtained, and thereby a dense, uniform, and highly smooth electrodeposited layer (aluminum metal layer) can be obtained. In this way, the formation of the sharp dendrite form of aluminum is prevented, making it difficult to cause a short circuit, and the lifespan of the aluminum battery can be improved. Since the aluminum nuclei are fine during the discharging process, the reaction area can be increased, thereby enhancing the reaction ability, strengthening the aluminum dissolution performance, and increasing the power capacity.

[0025] In some embodiments, the electron-withdrawing functional group is selected from among a cyano group, an amide group, an acyl chloride group, a carboxyl group, and esters, and is located at the 2-position, 3-position, or 4-position of the above-described pyridine-based compound (for example, the position shown in Structural Formula 1). As an example, the pyridine-based compound may be 4-cyanopyridine. Here, since the polarization ability of the cyano group at the 4-position is superior to that of the other positions, the pyridine-based compound can more easily form delocalized electrons on the cyano group, increasing the polarization ability of the pyridine-based compound. Therefore, the electron density of the nitrogen atom on the pyridine decreases, making it easier to adsorb onto the negative electrode. In this way, the electrodeposition potential increases, and the electrodeposited aluminum nuclei can be made finer and more uniform, but the present invention is not limited thereto.

[0026]

Chemical Formula

[0027] In some embodiments, the electrolytic solution does not contain an organic solvent and / or a lithium salt (LiPF6, LiBF4, LiClO4, LiASF6), but the present invention is not limited thereto, and depending on the requirements of the actual design, the electrolytic solution may contain an organic solvent and / or a lithium salt.

[0028] In some embodiments, in the electrolytic solution, the weight of 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, 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. When the weight ratio of the additive in the electrolyte exceeds 0.16 wt%, powder precipitates in the electrolyte, turbidity occurs, and a precipitation phenomenon occurs. Therefore, better performance can be achieved within the weight ratio range of the above-described 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%, but the present invention is not limited thereto.

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

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

[0033] In some embodiments, the aluminum halide includes aluminum chloride (AlCl3), and the ionic liquid includes 1-ethyl-3-methylimidazolium chloride, but the present invention is not limited thereto.

[0034] In some embodiments, due to the synergistic effect of the additive containing a pyridine-based compound and aluminum foil, copper foil, or nickel foil, a better effect can be achieved. Therefore, the negative electrode material preferably includes aluminum foil, copper foil, or nickel foil, but the present invention is not limited thereto.

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

[0036] In some embodiments, the material of the positive electrode includes nickel foil coated with graphite slurry, but the present invention is not limited thereto.

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

[0038] In some embodiments, the material of the separator includes glass fiber or other suitable polymer fiber / film, but the present invention is not limited thereto.

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

[0040] Hereinafter, with reference to Examples and Comparative Examples, the effects achievable by the aluminum battery of the present invention will be described more specifically. Also, the following Examples will be described, but details of materials used, processes, etc. may be appropriately changed without departing from the scope of the present invention, and the present invention should not be construed restrictively by the Examples described below.

[0041] <Example 1>

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

[0043] <Example 2>

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

[0045] <Example 3>

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

[0047] <Comparative Example 1>

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

[0049] The measurement results are as shown in FIGS. 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 the charge-discharge cycle of the aluminum battery to the discharge capacity value after the initial stabilization of the aluminum battery.

[0050]

Table 1

[0051] FIGS. 1 and 2 are schematic diagrams showing the surface analysis results of the examples and comparative examples. Here, FIGS. 1 and 2 are obtained by performing an electrochemical deposition reaction (the negative electrode is a copper foil and the positive electrode is an aluminum foil) using the electrolytes of Comparative Example 1 and Example 1, respectively, with a potentiostat (Autolab electrochemical workstation), electroplating aluminum metal onto the copper foil, with a current density of 6 mA and a deposition time of 30 minutes, and then performing surface analysis using an SEM electron microscope after obtaining the electroplated aluminum layer.

[0052] As can be seen from the results of FIG. 1, the surface formed by the electrolyte of Comparative Example 1 was clearly rough, and the aluminum nuclei were in a large and non-uniform state. Also, as can be seen from the results of FIG. 2, the surface formed by the electrolyte of Example 1 had high smoothness, and the electroplated layer was denser and more uniform. Also, since the electroplated layer was denser, the thickness of the electroplated layer was also smaller than that of the electroplated layer formed by the electrolyte of Comparative Example 1, thereby demonstrating that both the density and uniformity of the electroplated layer were surely 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 charge and discharge, but after 200 cycles, the power capacity retention rate became 46%. In Example 1, the power capacity retention rate was 94% in the first 50 cycles, and it was still 76% after 200 cycles of charge and discharge. In Example 2, the power capacity retention rate was 100% in the first 50 cycles, and it was still 76% after 200 cycles of charge and discharge. In Example 3, the power capacity retention rate was 100% in the first 50 cycles, and it continued to maintain 100% after 200 cycles of charge and discharge. As can be understood from this, the additive can effectively improve the electrical performance. As the concentration (addition amount) of the additive increases, the power capacity retention rate tends to be further improved. Therefore, the aluminum core forms a finer aluminum layer, increasing the surface area, and the dissolution reaction of aluminum is carried out more efficiently, indicating that the discharge capacity is less likely to decrease even after multiple cycles of charge and discharge.

[0054] Figure 3 is a schematic diagram showing the life test results after assembling in aluminum batteries in the examples and comparative examples. Here, Figure 3 shows the test results of power capacity and life obtained by using Example 1, Example 2, Example 3, and Comparative Example 1 as electrolytes, using aluminum foil as the negative electrode, using nickel foil coated with graphite paste as the positive electrode foil material, using glass fiber as the separator to assemble a coin-type aluminum battery (Coin Cell), and performing a charge and discharge test at a charge and discharge rate of 4C using a charge and discharge tester.

[0055] As can be seen from the results in FIG. 3, in terms of the life performance of aluminum batteries, the aluminum battery containing the electrolyte of Comparative Example 1 had an average of 121 cycles, the aluminum battery containing the electrolyte of Example 1 had 184 cycles, the aluminum battery containing the electrolyte of Example 2 had 204 cycles, and the aluminum battery containing the electrolyte of Example 3 had 220 cycles. Therefore, it is demonstrated that the aluminum batteries containing the electrolytes of Example 1, Example 2, and Example 3 achieved better life than the aluminum battery containing the electrolyte of Comparative Example 1. That is, increasing the additive does not adversely affect the life of the aluminum battery. Since a smooth electrodeposited layer is less likely to generate sharp dendrites, the life performance can be gradually improved due to the situation where the battery is less likely to cause a short circuit.

[0056] As described above, the present invention introduces an electrolyte containing a pyridine-based compound having an electron-withdrawing functional group into the design of an aluminum battery, and adjusts the charged state of nitrogen on the pyridine-based compound by the electron-withdrawing functional group to form fine aluminum nuclei. In this way, it is possible to suppress the generation of the dendrite form of aluminum metal during the charging process, make it less likely to cause a short circuit, and increase the reaction area during the discharging process. Therefore, the aluminum battery can have excellent performance in terms of life and / or electrical characteristics.

[0057] Although the present invention has been disclosed by the above embodiments, these are not for limiting the present invention. Those with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the scope of the following claims.

Industrial Applicability

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

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, and the pyridine-based compound has an electron-withdrawing functional group.

2. 2. The aluminum battery according to claim 1, wherein the electron-withdrawing functional group is selected from the group consisting of a cyano group, an amide group, an acyl chloride group, a carboxyl group, and an ester.

3. 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.

4. 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.

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

6. 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 %.

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

8. 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 %.

9. 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.

10. 2. The aluminum battery of claim 1, wherein the negative electrode comprises aluminum foil, copper foil, or nickel foil.

Images