Aluminum battery

Abstract

PURPOSE: To provide an aluminum battery capable of extending service life and maintaining more excellent power capacity performance.SOLUTION: An aluminum battery includes a positive electrode, a negative electrode, a separator, and an aqueous 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 aqueous electrolyte. When the aluminum battery operates, the positive electrode performs an intercalation mechanism and the negative electrode performs a chelation mechanism.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] The power capacity and lifespan of an aluminum battery are affected by many factors. For example, usually, the positive electrode material (e.g., graphite) has structural limitations. That is, when attempting to improve the power capacity performance of an aluminum battery, the structure is damaged and the lifespan is shortened. On the other hand, during the cycle charge and discharge process of an aluminum battery, aluminum plating is generated on the negative electrode and continues to grow into the form of aluminum dendrites. However, as the aluminum dendrite form continues to grow, it locally penetrates the separator, thus conducting the positive and negative electrodes to form a short circuit and shortening the lifespan.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Usually, the positive electrode material (e.g., graphite) has structural limitations. That is, when attempting to improve the power capacity performance of an aluminum battery, the structure is damaged and the lifespan is shortened. On the other hand, during the cycle charge and discharge process of an aluminum battery, aluminum plating is generated on the negative electrode and continues to grow into the form of aluminum dendrites. However, as the aluminum dendrite form continues to grow, it locally penetrates the separator, thus conducting the positive and negative electrodes to form a short circuit and shortening the lifespan.

Means for Solving the Problems

[0004] The present invention provides an aluminum battery capable of extending the lifespan and maintaining more excellent power capacity performance.

[0005] The aluminum battery of the present invention includes a positive electrode, a negative electrode, a separator, and an aqueous electrolyte. The separator is installed between the positive electrode and the negative electrode. The aqueous electrolyte is impregnated into the separator, the positive electrode, and the negative electrode. When the aluminum battery operates, the positive electrode executes an intercalation mechanism, and the negative electrode executes a chelating mechanism.

[0006] In one embodiment of the present invention, when the above-described aluminum battery operates, the active material in the aqueous electrolyte is aluminum ions.

[0007] In one embodiment of the present invention, the above-described aqueous electrolyte contains water and an aluminum salt.

[0008] In one embodiment of the present invention, the weight ratio of the above-described aluminum salt in the aqueous electrolyte is between 30 wt% and 50 wt%, and the total weight ratio of water and the aluminum salt is 100 wt%.

[0009] In one embodiment of the present invention, the above-described positive electrode includes a first metal substrate and a first coating layer. The first coating layer is installed on the first metal substrate, and the first coating layer contains a metal oxide.

[0010] In one embodiment of the present invention, the weight ratio of the above-described metal oxide in the first coating layer is 80 wt% or more and less than 100 wt%.

[0011] In one embodiment of the present invention, the above-described negative electrode includes a second metal substrate and a second coating layer. The second coating layer is installed on the second metal substrate, and the second coating layer contains a conjugated organic molecule.

[0012] In one embodiment of the present invention, the above-described conjugated organic molecule includes a compound containing an acid anhydride structure, a derivative of an acid anhydride structure, a composite of a compound having an acid anhydride structure and a carbon material, or a composite of a derivative of an acid anhydride structure and a carbon material.

[0013] In one embodiment of the present invention, the weight ratio in the second coating layer of the conjugated organic molecule described above is 80 wt% or more and less than 100 wt%.

[0014] In one embodiment of the present invention, the thickness of the separator described above is between 200 micrometers (μm) and 500 μm.

Advantages of the Invention

[0015] As described above, since the aluminum battery of the present invention selects an aqueous electrolyte, small-sized ions that are difficult to destroy the positive electrode structure are generated, and the intercalation mechanism can be effectively executed. The chelation mechanism performed by the aforementioned small-sized ions at the negative electrode replaces the electrochemical mechanism, so the formation of the dendrite form of aluminum can be avoided. In this way, the lifespan can be extended and better power capacity performance can be maintained.

[0016] In order to more clearly understand the above characteristics 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

Modes for Carrying Out the Invention

[0018] To make the content of the present invention easier to understand, embodiments are given below to show that the present invention is an example that can be surely implemented. For clear explanation, many practical details are described together 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 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 that normally 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 described endpoint values and ranges between the described endpoint values. For example, if a dimension range is between a first numerical value and a 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.

[0022] FIG. 1 is a schematic diagram showing the structure of an aluminum battery in one embodiment of the present invention. Referring to FIG. 1, in this embodiment, the aluminum battery 100 includes a positive electrode 110, a negative electrode 120, a separator 130, and an aqueous electrolyte 140. The separator 130 is installed between the positive electrode 110 and the negative electrode 120, and the aqueous electrolyte 140 is impregnated into the separator 130, the positive electrode 110, and the negative electrode 120.

[0023] When the aluminum battery 100 operates, the positive electrode 110 executes an intercalation mechanism, and the negative electrode 120 executes a chelation mechanism. As a result, since the aluminum battery 100 of the present embodiment selects an aqueous electrolyte 140, small-sized ions that are difficult to destroy the structure of the positive electrode 110 are generated, and the intercalation mechanism can be effectively executed. The chelation mechanism performed by the aforementioned small-sized ions at the negative electrode 130 can replace the electrochemical mechanism, so that the formation of the dendrite form of aluminum can be avoided. In this way, the lifespan can be extended and better power capacity performance can be maintained.

[0024] For example, in the configuration of the current aluminum battery, the positive electrode usually uses a graphite material, and the electrolyte is composed of aluminum chloride and an ionic liquid. In this arrangement, the operating mechanism of the positive electrode is an intercalation reaction and charge storage by AlCl4 - (The size is about 0.5 nanometers) ions. That is, its operating mechanism is based on inserting AlCl4 - ions into the gaps (interlayer voids) of the layered structure of graphite. However, during insertion, since the size of the AlCl4 - ions is larger than the interlayer distance of graphite (for example, 0.335 nanometers), it causes structural damage during the cycle charge and discharge process of the aluminum battery, and its operating stability becomes insufficient. On the other hand, the aluminum plating that forms the dendrite form of aluminum is generated based on the electrochemical mechanism of the negative electrode. When the dendrite form of aluminum penetrates the separator and contacts the positive electrode, an additional electron path is generated, short-circuiting the battery.

[0025] To improve the above problems, in this embodiment, the positive electrode 110 includes a first metal substrate 111 and a first coating layer 112 disposed thereon, and the negative electrode 120 includes a second metal substrate 121 and a second coating layer 122. Here, the first coating layer 112 includes a metal oxide (a structure that can be easily intercalated), and the second coating layer 122 includes a conjugated organic molecule (which can attract the positively charged active material by being negatively charged). Also, the aqueous electrolyte 140 includes water and an aluminum salt (which can generate small-sized intercalation active materials such as aluminum ions (Al 3+ )) etc., and AlCl4 - is not generated. In this way, by utilizing the structural stability of the metal oxide, the power capacity retention rate during the cyclic charge and discharge of the aluminum battery 100 can be improved, and the charge exchange (which can be called a chelate structure rather than a physical intercalation mechanism) between the conjugated organic molecule and the active material (Al 3+ ) in the electrolyte is utilized so that the aluminum battery 100 can effectively perform charge and discharge with a high power capacity, but the present invention is not limited thereto.

[0026] Also, since the aluminum battery 100 of this embodiment does not generate dendrites, a thinner separator 130 can be used, and its volume energy density can be improved. In some embodiments, the thickness of the separator 130 is between 200 micrometers and 500 micrometers, but the present invention is not limited thereto.

[0027] In some embodiments, the first coating layer 112 and the second coating layer 122 can be manufactured by respectively preparing the corresponding components in the form of a slurry by an appropriate method, coating them on the first metal substrate 111 and the second metal substrate 121 respectively, and drying them, but the present invention is not limited thereto.

[0028] In some embodiments, the total solid content in the slurry of the first coating layer 112 occupies between 20 wt% and 40 wt% of the solid content of the entire slurry, and the total solid content in the slurry of the second coating layer 122 occupies between 5 wt% and 30 wt% of the solid content of the entire slurry, but the present invention is not limited thereto.

[0029] In some embodiments, the range of the surface density (coating film weight per unit area) of the coating film surface of the first coating layer 112 is 2 ~ 10 mg / cm 2 and the range of the surface density (coating film weight per unit area) of the coating film surface of the second coating layer 122 is 0.5 mg / cm 2 ~ 10 mg / cm 2 However, the present invention is not limited thereto.

[0030] In some embodiments, the first coating layer 112 is installed between the first metal substrate 111 and the separator 130 and is in direct contact with the separator 130. The second coating layer 122 is installed between the second metal substrate 121 and the separator 130 and is in direct contact with the separator 130. However, the present invention is not limited thereto.

[0031] In some embodiments, the weight ratio of the aluminum salt in the aqueous electrolyte 140 is between 30 wt% and 50 wt%, and the total weight ratio of water and the aluminum salt is 100 wt%. However, the present invention is not limited thereto.

[0032] In some embodiments, the concentration of the aluminum salt in the aqueous electrolyte 140 is between 1 M and 2 M, for example, 2 M. However, the present invention is not limited thereto.

[0033] In some embodiments, the aluminum salt includes aluminum trifluoromethanesulfonate (Al(OTf)3). However, the present invention is not limited thereto.

[0034] In some embodiments, the weight ratio of the metal oxide in the first coating layer 112 is 80 wt% or more and less than 100 wt% (for example, between 80 wt% and 90 wt%), but the present invention is not limited thereto.

[0035] In some embodiments, the metal oxide includes vanadium trioxide (V2O3), but the present invention is not limited thereto.

[0036] In some embodiments, the first coating layer 112 further includes a conductive carbon material and an adhesive. The weight ratio of the conductive carbon material in the first coating layer 112 is between 5 wt% and 10 wt%, and the weight ratio of the adhesive in the first coating layer 112 is between 8 wt% and 10 wt%. The total weight ratio of the metal oxide, the conductive carbon material, and the adhesive is 100 wt%, but the present invention is not limited thereto. Here, the conductive carbon material includes conductive carbon black (Super-P), graphene, graphene oxide, or carbon nanotubes, and the adhesive includes a suitable rubber-based material (for example, carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), or a mixture thereof), but the present invention is not limited thereto.

[0037] In some embodiments, the weight ratio of the conjugated organic molecule in the second coating layer 122 is 80 wt% or more and less than 100 wt%, but the present invention is not limited thereto.

[0038] In some embodiments, the second coating layer 122 further includes a conductive carbon material and an adhesive. The weight ratio of the conductive carbon material in the second coating layer 122 is between 8 wt% and 10 wt%, and the weight ratio of the adhesive in the second coating layer 122 is between 8 wt% and 15 wt%. The total weight ratio of the conjugated organic molecule, the conductive carbon material, and the adhesive is 100 wt%, but the present invention is not limited thereto. Here, the conductive carbon material includes conductive carbon black, graphene, graphene oxide, or carbon nanotube (CNT), and the adhesive includes a suitable rubber-based material or polyvinylidene fluoride material, but the present invention is not limited thereto.

[0039] In some embodiments, the conjugated organic molecule includes a compound containing an acid anhydride structure, a derivative of the acid anhydride structure, a composite of a compound containing the acid anhydride structure and a carbon material, or a composite of a derivative of the acid anhydride structure and a carbon material. For example, the compound containing the acid anhydride structure includes perylene tetracarboxylic dianhydride (PTCDA, CAS no: 128-69-8), and the derivative of the acid anhydride structure includes 3,4,9,10-perylene tetracarboxylic diimide (PTCDI, CAS no: 81-33-4), N,N’-dimethyl-3,4,9,10-perylene dicarboximide (MePTC, CAS no: 5521-31-3), or anthraquinone. The composite of a compound containing the acid anhydride structure and a carbon material includes a composite of perylene tetracarboxylic dianhydride and carbon nanotube (CNT), a composite of perylene tetracarboxylic dianhydride and activated carbon (AC), a composite of perylene tetracarboxylic dianhydride and graphene oxide (GO), and the composite of a derivative of the acid anhydride structure and a carbon material includes a composite of 3,4,9,10-perylene tetracarboxylic diimide and carbon nanotube (CNT), a composite of 3,4,9,10-perylene tetracarboxylic diimide and activated carbon (AC), a composite of 3,4,9,10-perylene tetracarboxylic diimide and graphene oxide (GO), but the present invention is not limited thereto. Here, the derivative of the acid anhydride structure is defined as a conjugated organic bonding compound or polymer having an acid anhydride structure or a similar acid anhydride.

[0040] In some embodiments, the materials of the first metal substrate 111 and the second metal substrate 112 include aluminum foil, titanium foil, nickel foil, or other suitable metal foil materials, but the present invention is not limited thereto.

[0041] In some embodiments, the thickness range of the first coating layer 121 is between 100 micrometers and 120 micrometers, and the thickness range of the second coating layer 122 is between 10 micrometers and 200 micrometers. For example, if the thickness of the second coating layer 122 exceeds 250 micrometers, the electrode is likely to be damaged. Therefore, the second coating layer 122 has better operability between 10 micrometers and 200 micrometers, but the present invention is not limited thereto. Here, the thicknesses of the first metal substrate 111 and the second metal substrate can be determined according to actual design requirements, so the present invention is not limited thereto.

[0042] In some embodiments, the material of the separator 130 includes glass fiber or the like, but the present invention is not limited thereto.

[0043] Hereinafter, with reference to Examples and Comparative Examples, the effects achievable by the aluminum battery of the present invention will be described more specifically. In addition, 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.

[0044] <Comparative Example 1>

[0045] Nickel foil was used as the metal substrate of the positive electrode, and after preparing a slurry (composed of 90 wt% graphite, 2 wt% conductive carbon black (super P), 1.5 wt% sodium carboxymethyl cellulose (CMC), and 6.5 wt% styrene-butadiene rubber (SBR), referred to as the first slurry) by the wet mixing method, it was coated on the nickel foil and dried to form a nickel foil positive electrode having a graphite coating layer (the thickness of the coating layer was 110 micrometers, and the areal density was 12.5 mg / cm 2) Aluminum foil (metal substrate) (thickness: 50 micrometers) was used as the negative electrode (coating layer thickness: 110 micrometers), and it was assembled as a CR2032 coin cell together with a non-aqueous electrolyte (aluminum chloride / 1-ethyl-3-methylimidazolium chloride, molar ratio: 1.8:1, 150 μL) to obtain the aluminum battery of Comparative Example 1. Here, since the wet mixing method is a slurry manufacturing method well-known to those with ordinary knowledge in the technical field of stirring and dispersing the above components and a solvent (N-methylpyrrolidone, NMP), a detailed description is omitted here.

[0046] <Example 1>

[0047] After preparing a second slurry (composed of 80 wt% vanadium trioxide, 10 wt% conductive carbon black (super P), and 10 wt% binder (polyvinylidene fluoride (PVDF))) by the wet mixing method, it was applied onto a titanium foil (metal substrate) with a thickness of 250 micrometers using a square applicator, and then dried at 100 °C for 1 hour to form a coating layer (thickness after drying: 70 micrometers) to obtain the positive electrode. Next, after preparing a third slurry (composed of 56 wt% perylene tetracarboxylic dianhydride (PTCDA), 24% graphene oxide (GO), 10 wt% conductive carbon black, and 10 wt% polyvinylidene fluoride (PVDF)) by the wet mixing method, it was applied onto the titanium foil (metal substrate) to form a coating layer to obtain the negative electrode (thickness: 45.2 micrometers). Then, it was assembled as a CR20232 coin cell together with an aqueous electrolyte (2M Al(OTf)3 (weight ratio of water: 40 wt%, weight ratio of Al(OTf)3: 60 wt%, 150 μL)) to obtain the aluminum battery of Example 1. Here, water was used as the solvent for the second slurry, and the zirconia balls were rotated and milled in a container by the rotational centrifugal method to improve the uniform dispersibility of the materials in the second slurry.

[0048] <Example 2>

[0049] The aluminum battery of Example 2 is similar to the manufacturing method of the aluminum battery of Example 1, but the difference is that the third slurry is composed of 56 wt% anthraquinone (AQ), 24% activated carbon (AC), 10 wt% conductive carbon black, 1.88 wt% sodium carboxymethyl cellulose (CMC), and 8.12 wt% styrene butadiene rubber (SBR). Also, the thickness of the negative electrode is 60 micrometers.

[0050] <Example 3>

[0051] The aluminum battery of Example 3 is similar to the manufacturing method of the aluminum battery of Example 1, but the difference is that the third slurry is composed of 80 wt% 3,4,9,10 - perylenetetracarboxylic diimide (PTCDI), 10 wt% conductive carbon black, 1.88 wt% sodium carboxymethyl cellulose (CMC), and 8.12 wt% styrene butadiene rubber (SBR). Also, the thickness of the negative electrode is 58.3 micrometers.

[0052] <Example 4>

[0053] The aluminum battery of Example 4 is similar to the manufacturing method of the aluminum battery of Example 1, but the difference is that the third slurry is composed of 56 wt% 3,4,9,10 - perylenetetracarboxylic diimide (PTCDI), 24% graphene oxide (GO), 10 wt% conductive carbon black, and 10 wt% polyvinylidene fluoride (PVDF). Also, the thickness of the negative electrode is 22.5 micrometers.

[0054] Figure 2 is a schematic diagram showing the results of the power capacity tests of the examples and comparative examples. Figure 3 is a schematic diagram showing the results of the life tests of the examples and comparative examples. Here, Figures 2 and 3 are for chronopotentiometry (where the battery is charged / discharged at a constant current, and the cut-off potential conditions for switching from charging to discharging / from discharging to charging are set. This constant current is usually a multiple of the weight of V2O3 in the positive electrode coating layer, and in this application, the multiple is 0.26 times. For example, when the V2O3 in the positive electrode coating layer is 1 g, the current value is 0.26 A. Set the cut-off potential, charge at a constant current until 1.8 V, then switch to discharging, discharge until 0.1 V, and then switch back to charging again. In this way, repeat one charge-discharge cycle once, and the Coulomb efficiency is calculated by calculating the ratio of the discharge capacity to the charge capacity of that cycle), and the Coulomb efficiency is calculated by dividing the discharge capacity by the charge capacity. All cycle numbers in which the Coulomb efficiency exceeds 80% during the charge-discharge process of the battery are used as the criteria for judging the life.

[0055] The test results are as shown in Figures 2 to 3, and the conclusions are as follows. As shown in Figures 2 and 3, by using an acid anhydride-based material as the negative electrode (PTCDI-based material or anthraquinone) and combining it with a metal oxide (V2O3) positive electrode and an Al(OTf)3 electrolyte, the power capacity performance of the battery was significantly improved. The average power capacity of the battery increased from 63.3 mAh / g to 157.2 mAh / g (the highest capacity in Example 4), the power capacity performance improved by 2.4 times, the average life of the aluminum battery extended from 49 cycles to 357 cycles, and the life extended by 7.2 times. Therefore, the aluminum battery of the present invention can surely extend its life and maintain more excellent power capacity performance due to the synergistic effect of the positive electrode with an intercalation mechanism, the negative electrode with a chelate mechanism, and the aqueous electrolyte.

[0056] As described above, since the aluminum battery of the present invention selects an aqueous electrolyte solution, small-sized ions that are difficult to destroy the positive electrode structure are generated, and the intercalation mechanism can be effectively executed. The chelating mechanism performed by the aforementioned small-sized ions at the negative electrode can replace the electrochemical mechanism, so that the formation of the dendrite form of aluminum can be avoided. In this way, the lifespan can be extended and better power capacity performance can be maintained.

[0057] The present invention has been disclosed according to the above embodiments, but 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 determined by the scope of the following claims.

Industrial Applicability

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

Explanation of Reference Numerals

[0059] 100 Aluminum battery 110 Positive electrode 111 First metal substrate 112 First coating layer 120 Negative electrode 121 Second metal substrate 122 Second coating layer 130 Separator 140 Aqueous electrolyte solution

Claims

1. A positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an aqueous electrolyte solution impregnated in the separator, the positive electrode, and the negative electrode, wherein when the aluminum battery operates, the positive electrode executes an intercalation mechanism and the negative electrode executes a chelation mechanism.

2. The aluminum battery according to claim 1, wherein when the aluminum battery operates, the active material in the aqueous electrolyte solution is aluminum ions.

3. The aluminum battery according to claim 1, wherein the aqueous electrolyte solution contains water and an aluminum salt.

4. The aluminum battery according to claim 3, wherein the weight ratio of the aluminum salt in the aqueous electrolyte solution is between 30 wt% and 50 wt%, and the total weight ratio of water and the aluminum salt is 100 wt%.

5. The aluminum battery according to claim 1, wherein the positive electrode includes a first metal substrate and a first coating layer, the first coating layer is provided on the first metal substrate, and the first coating layer contains a metal oxide.

6. The aluminum battery according to claim 5, wherein the weight ratio of the metal oxide in the first coating layer is 80 wt% or more and less than 100 wt%.

7. The aluminum battery according to claim 1, wherein the negative electrode includes a second metal substrate and a second coating layer, the second coating layer is provided on the second metal substrate, and the second coating layer contains a conjugated organic molecule.

8. The aluminum battery according to claim 7, wherein the conjugated organic molecule includes a compound containing an acid anhydride structure, a derivative of the acid anhydride structure, a composite of a compound containing the acid anhydride structure and a carbon material, or a composite of a derivative of the acid anhydride structure and a carbon material.

9. The aluminum battery according to claim 7, wherein the weight ratio of the conjugated organic molecule in the second coating layer is 80 wt% or more and less than 100 wt%.

10. The aluminum battery according to claim 1, wherein the thickness of the separator is between 200 micrometers and 500 micrometers.

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