Aluminum battery

Abstract

PURPOSE: To provide an aluminum battery capable of effectively improving service life and maintaining excellent performance.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 separator, the positive electrode, and the negative electrode are impregnated with the electrolyte. The electrolyte contains aluminum halide, ionic liquid, and an additive, and the additive contains an isocyanate-based compound.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In the manufacturing process of an aluminum battery, since external moisture easily penetrates into the electrolyte, harmful gases are likely to be generated during the charge and discharge process of the aluminum battery, resulting in a performance decline (for example, a decline in Coulomb efficiency). Furthermore, the power storage reaction of an aluminum battery is the precipitation and dissolution of aluminum. However, when the rates of aluminum precipitation and dissolution cannot maintain equilibrium, or when aluminum dendrite forms are generated due to the accumulation of charges on the electrode surface, the service life will decline in both cases.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In an aluminum battery, harmful gases are likely to be generated during the charge and discharge process, resulting in a performance decline (for example, a decline in Coulomb efficiency). On the other hand, the power storage reaction of an aluminum battery is the precipitation and dissolution of aluminum. However, when the rates of aluminum precipitation and dissolution cannot maintain equilibrium, or when aluminum dendrite forms are generated due to the accumulation of charges on the electrode surface, the service life will decline in both cases.

Means for Solving the Problems

[0004] The present invention provides an aluminum battery that can effectively improve the service life and maintain excellent performance at the same time.

[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 into the separator, the positive electrode, and the negative electrode. The electrolyte contains aluminum halide, an ionic liquid, and an additive, and the additive contains an isocyanate-based compound.

[0006] In one embodiment of the present invention, the above-mentioned isocyanate-based compound further contains an acrylic acid functional group.

[0007] In one embodiment of the present invention, the weight ratios of the above-mentioned aluminum halide, ionic liquid, and additive in the electrolyte are, in descending order, aluminum halide, ionic liquid, and additive.

[0008] In one embodiment of the present invention, the weight ratio of the above-mentioned additive in the electrolyte is 0.2 wt% or more.

[0009] In one embodiment of the present invention, the weight ratio of the above-mentioned aluminum halide in the electrolyte is between 49 wt% and 65 wt%.

[0010] In one embodiment of the present invention, the weight ratio of the above-mentioned ionic liquid in the electrolyte is between 35 wt% and 51 wt%.

[0011] In one embodiment of the present invention, the total weight ratio of the above-mentioned aluminum halide, ionic liquid, and additive in the electrolyte is 100 wt%.

[0012] In one embodiment of the present invention, the above-mentioned aluminum halide contains aluminum chloride, and the ionic liquid contains 1-ethyl-3-methylimidazolium chloride.

[0013] In one embodiment of the present invention, the above-mentioned isocyanate-based compound is arranged to form an amine-based compound during the operation of the aluminum battery.

[0014] In one embodiment of the present invention, the above-mentioned amine-based compound adsorbs on the surface of the negative electrode during the operation of the aluminum battery.

Advantages of the Invention

[0015] As described above, the present invention introduces an electrolyte containing an isocyanate-based compound into the design of an aluminum battery. By the reaction of the isocyanate functional group with moisture in the electrolyte, the water content in the electrolyte is reduced to suppress the generation of harmful gases, and the aluminum dissolution reaction at the negative electrode is promoted to suppress the formation of aluminum dendrite morphology. In this way, the service life can be effectively improved while maintaining excellent performance.

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

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0018] To make it easier to understand the content of the present invention, embodiments are given below to show that the present invention is an example that can be surely implemented. For the sake of 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 the known aluminum battery design rules is omitted in the text. However, those with ordinary knowledge in the technical field can design according to the actual needs without departing from the spirit and scope of the present invention.

[0020] The present invention will be further comprehensively described with reference to the drawings of the present embodiment. However, the present invention can be embodied in various different forms and should not be limited to the embodiments described in the text. The thickness, dimensions, or sizes of the layers and regions in the drawings are exaggerated for clarity. The same or similar reference numerals indicate the same or similar elements and will not be repeatedly explained in the following paragraphs.

[0021] Unless otherwise defined, all technical terms (including technical and scientific terms) used in the text have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs.

[0022] Unless otherwise explained, the term "between ~" used to define a numerical range in this specification includes values equal to the described endpoint values and the range between the described endpoint values. For example, if the dimension range is between the first numerical value and the second numerical value, it means that the dimension range may include the first numerical value, the second numerical value, and any value between the first numerical value and the second numerical value.

[0023] First, it should be noted that the present text is applicable to the situation where trace amounts of moisture are contained in the electrolyte of an aluminum battery. Since the aforementioned trace amounts of moisture are derived from the external environment during the manufacturing process, the weight of the moisture may be ignored when describing the total weight of the electrolyte below.

[0024] 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 by an appropriate method known in the field of aluminum batteries, but the present invention is not limited thereto.

[0025] Also, the electrolyte includes aluminum halide, an ionic liquid, and an additive, and the additive includes an isocyanate-based compound. Thereby, this embodiment introduces an electrolyte containing an isocyanate-based compound into the design of the aluminum battery. By the reaction of the isocyanate functional group with the moisture in the electrolyte, the water content rate in the electrolyte is reduced to suppress the generation of harmful gases, and the dissolution aluminum reaction of the negative electrode is promoted to suppress the formation of aluminum dendrite morphology. In this way, the service life can be effectively improved while maintaining excellent performance. It should be noted that since the present invention is the design of an aluminum battery, the aluminum halide and the ionic liquid that can generate active substances such as aluminum ions are used in the electrolyte, rather than the electrolyte components selected for other types of batteries.

[0026] More specifically, the isocyanate functional group is arranged to form an amine compound during the operation of the aluminum battery. That is, the isocyanate functional group reacts with moisture in the electrolyte to generate an amine compound. As a result, the water content can be effectively reduced, and the generation of gases such as hydrogen chloride (HCl) that have an adverse effect on the aluminum battery can be suppressed. In addition, the aforementioned amine compound adsorbs on the surface of the negative electrode during the operation (e.g., discharge) of the aluminum battery due to the lone pair of electrons (Lewis base) on its nitrogen, and reacts with Al 3+ (Lewis acid) on the surface of the negative electrode to form a metal complex, thereby improving the dissolution ability of aluminum. Therefore, during the cycle charge and discharge process of the aluminum battery, the dendrite form of aluminum can be effectively suppressed, and the battery life can be extended.

[0027] In some embodiments, carbon dioxide is formed along with the reaction of the isocyanate functional group and the electrolyte. However, since this gas does not have an adverse effect on the aluminum battery, it is not a harmful gas. However, the present invention is not limited thereto.

[0028] In some embodiments, the isocyanate compound further includes an acrylic acid functional group and does not include a benzene ring functional group. For example, the isocyanate compound includes 2-isocyanatoethyl acrylate (C6H7NO3). Therefore, the generated amine compound may be an isocyanate group (C5H4NO2, chemical formula: H-N=C=O, chemical structural formula: refer to the following chemical formula), but the present invention is not limited thereto. The isocyanate compound may be other analogs of 2-isocyanatoethyl acrylate, as long as it has an isocyanate functional group and can react with moisture in the electrolyte to generate an amine compound, it shall be included in the protection scope of the present invention. Here, the amine compound varies depending on the type of the isocyanate compound. [Chemical formula]

[0029] In some embodiments, the weight ratios in the electrolyte of aluminum halide, ionic liquid, and additive are, in descending order, aluminum halide, ionic liquid, additive, but the present invention is not limited thereto.

[0030] In some embodiments, the weight ratio of the additive in the electrolyte is greater than or equal to 0.2 wt% (0.2 wt% or more), more preferably less than or equal to 5 wt% (5 wt% or less), whereby it is possible to prevent the aluminum battery from malfunctioning due to the action of the additive, but the present invention is not limited thereto.

[0031] 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.

[0032] 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.

[0033] 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 only of aluminum halide, ionic liquid, and an additive containing an isocyanate-based compound. Here, the weight of trace moisture in the electrolyte may be ignored.

[0034] In some embodiments, the aluminum halide contains aluminum chloride (AlCl3), and the ionic liquid contains 1-ethyl-3-methylimidazolium chloride. Here, since the aforementioned ionic liquid is a hydrophilic ionic liquid, when using the aforementioned ionic liquid or its analog, a more remarkable improvement effect can be obtained, but the present invention is not limited thereto.

[0035] In some embodiments, due to the synergistic effect of the additive containing the isocyanate compound and the aluminum foil, a better effect can be obtained. Therefore, the negative electrode material more preferably includes an aluminum foil, but the present invention is not limited thereto.

[0036] In some embodiments, the thickness of the negative electrode is between 10 micrometers and 100 micrometers, but the present invention is not limited thereto.

[0037] In some embodiments, the positive electrode material includes a graphite carbon-based material, a conductive assistant, and an adhesive. The conductive assistant includes conductive carbon black (super P), and the adhesive includes carboxymethyl cellulose, styrene-butadiene rubber, or a combination thereof, but the present invention is not limited thereto.

[0038] In some embodiments, the thickness of the positive electrode is between 100 micrometers and 300 micrometers, but the present invention is not limited thereto.

[0039] Hereinafter, with reference to Example 1 to Example 5 and Comparative Example 1, the effects achievable by the aluminum battery of the present invention will be described more specifically. Also, although Example 1 to Example 5 are described below, 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 Example 1 to Example 5 described below.

[0040] <Example 1>

[0041] An aluminum foil (thickness 0.05 millimeter (mm)) was used as the negative electrode, and a graphite slurry was applied onto a nickel foil (thickness 0.05 millimeter) to fabricate the positive electrode. Next, glass fiber was provided as the separator. Thereafter, the negative electrode, separator, and positive electrode were arranged in this order, and an electrolytic solution composed of aluminum chloride (aluminum halide), 1-ethyl-3-methylimidazolium chloride (ionic liquid), and isocyanate ethyl acrylate (additive) was injected and sealed to obtain the aluminum battery of Example 1. Here, the weight ratio of aluminum chloride in the electrolytic solution was 58.97 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride (EMIC) in the electrolytic solution was 36.03 wt%, and the weight ratio of isocyanate ethyl acrylate in the electrolytic solution was 5 wt%.

[0042] <Example 2>

[0043] The aluminum battery of Example 2 is similar to the aluminum battery of Example 1, but the difference is that the weight ratio of aluminum chloride in the electrolytic solution was 61.45 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride (EMIC) in the electrolytic solution was 37.54 wt%, and the weight ratio of isocyanate ethyl acrylate in the electrolytic solution was 1 wt%.

[0044] <Example 3>

[0045] The aluminum battery of Example 3 is similar to the aluminum battery of Example 1, but the difference is that the weight ratio of aluminum chloride in the electrolytic solution was 61.6 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride in the electrolytic solution was 37.6 wt%, and the weight ratio of isocyanate ethyl acrylate in the electrolytic solution was 0.8 wt%.

[0046] <Example 4>

[0047] The aluminum battery of Example 4 is similar to the aluminum battery of Example 1, but the difference is that the weight ratio of aluminum chloride in the electrolyte is 61.8 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride in the electrolyte is 37.6 wt%, and the weight ratio of isocyanate ethyl acrylate in the electrolyte is 0.6 wt%.

[0048] <Example 5>

[0049] The aluminum battery of Example 5 is similar to the aluminum battery of Example 1, but the difference is that the weight ratio of aluminum chloride in the electrolyte is 61.9 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride in the electrolyte is 37.8 wt%, and the weight ratio of isocyanate ethyl acrylate in the electrolyte is 0.4 wt%.

[0050] <Example 6>

[0051] The aluminum battery of Example 6 is similar to the aluminum battery of Example 1, but the difference is that the weight ratio of aluminum chloride in the electrolyte is 62 wt%, the weight ratio of 1-ethyl-3-methylimidazolium chloride in the electrolyte is 37.8 wt%, and the weight ratio of isocyanate ethyl acrylate in the electrolyte is 0.2 wt%.

[0052] <Comparative Example 1>

[0053] The aluminum battery of Comparative Example 1 is similar to the aluminum battery of Example 1, but the difference is that the electrolyte is composed of aluminum chloride (aluminum halide) and 1-ethyl-3-methylimidazolium chloride (ionic liquid) and does not contain an additive of an isocyanate compound, the weight ratio of aluminum chloride in the electrolyte is 62 wt%, and the weight ratio of 1-ethyl-3-methylimidazolium chloride in the electrolyte is 38 wt%.

[0054] Tests were conducted on Examples 1 to 6 and Comparative Example 1, and the results are as shown in Figures 1 to 7, and the conclusions are as follows.

[0055] Figure 1 is a diagram showing the results of the moisture content tests of Examples 1 and 2 and Comparative Example 1, and the moisture content of the electrolyte was measured using a Coulomb moisture meter. As can be seen from the results of Figure 1, in Examples 1 and 2, the average moisture content decreased by 62.6 to 89.5 ppm compared with Comparative Example 1. Therefore, it is shown that the isocyanate functional group has indeed reacted with the moisture in the electrolyte to form an amine compound (C5H4NO2) and CO2, resulting in a decrease in the moisture content.

[0056] Figure 2 is a diagram showing the results of the active substance tests of Examples 2 to 6, and Raman spectroscopy was used to analyze whether the signals of active substances such as AlCl4 - , Al2Cl7 - , EMI + had disappeared. As can be seen from the results of Figure 2, within the range of the addition ratios of Examples 2 to 6, none of them affected the concentration of the active substances in the electrolyte. That is, within the range of the addition ratios of Examples 2 to 6, all aluminum batteries can operate normally.

[0057] Figure 3 is a schematic diagram showing the results of the Coulomb efficiency tests of Examples 1, 2, 4 and Comparative Example 1. Figure 4 is a schematic diagram showing the results of the life tests of Examples 1, 2, 4 and Comparative Example 1. Figure 5 is a partial schematic diagram of the electrochemical device used in the cycle charge-discharge experiment of the present invention. Here, the aluminum battery is a soft-pack aluminum battery, and the intervals between the negative electrode 110, the positive electrode 120, and the electrolyte 130 of the aluminum battery are fixed by the fixing member 102 (for example, a slide glass) in Figure 5 to fix the positions of the negative electrode 110 and the positive electrode 120, and the test was carried out at a charge-discharge rate of 4C. As can be seen from the results of Figures 4 and 5, in Examples 1, 2, and 4, compared with Comparative Example 1, as the ratio of the additive increases, the Coulomb efficiency of the battery improves, and the life also shows a similar trend. Therefore, by adding an electrolyte containing an isocyanate-based compound, the dissolution effect of the aluminum negative electrode can be significantly improved, and at the same time, it is shown that the generation of dendrites can be suppressed and the life of the battery can be extended.

[0058] Figures 6 and 7 are schematic diagrams showing the results of the corrosion degree tests of Comparative Example 1 and Example 2, respectively, and the corrosion degree tests were carried out using a scanning electron microscope. As can be seen from the results of Figures 6 and 7, since an amine-based compound is generated by the reaction of the isocyanate functional group with water in the electrolyte, it adsorbs on the surface of the aluminum negative electrode and reacts with Al 3+ (Lewis acid) to form a metal complex, thereby promoting the dissolution reaction of the aluminum negative electrode and making the corrosion distribution more uniform.

[0059] As described above, the present invention introduces an electrolyte containing an isocyanate-based compound into the design of an aluminum battery. By the reaction of the isocyanate functional group with moisture in the electrolyte, the water content in the electrolyte is reduced to suppress the generation of harmful gases, and the aluminum dissolution reaction of the negative electrode is promoted to suppress the formation of aluminum dendrite morphology. In this way, the service life can be effectively improved while maintaining excellent performance.

[0060] Although the present invention has been disclosed according to the above embodiments, these are not intended to limit the present invention. Those having ordinary knowledge in the relevant 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 claims described below.

Industrial Applicability

[0061] The aluminum battery can be applied in the field of aluminum batteries.

Explanation of Reference Numerals

[0062] 102 fixing member 110 negative electrode 120 positive electrode 130 electrolyte

Claims

1. a positive electrode, 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, wherein the electrolyte contains aluminum halide, an ionic liquid, and an additive, and the additive contains an isocyanate-based compound, an aluminum battery.

2. The aluminum battery according to claim 1, wherein the isocyanate-based compound further contains an acrylic acid functional group.

3. The aluminum battery according to claim 1, wherein the weight ratio in the electrolyte of the aluminum halide, the ionic liquid, and the additive is, in descending order, aluminum halide, ionic liquid, additive.

4. The aluminum battery according to claim 1, wherein the weight ratio of the additive in the electrolyte is 0.2 wt% or more.

5. 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. 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%.

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

9. The aluminum battery according to claim 1, wherein the isocyanate-based compound is arranged to form an amine-based compound during operation of the aluminum battery.

10. The aluminum battery according to claim 9, wherein the amine-based compound adsorbs on the surface of the negative electrode during operation of the aluminum battery.

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