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 technology]

[0002] The power capacity and lifespan of aluminum batteries are affected by many factors. For example, positive electrode materials (e.g., graphite) typically have structural limitations. Therefore, attempts to improve the power capacity of aluminum batteries result in structural destruction and shortened lifespan. Meanwhile, during the charge-discharge cycle of an aluminum battery, aluminum plating forms on the negative electrode and continues to grow, forming aluminum dendrites. As the aluminum dendrites continue to grow, they can locally penetrate the separator, causing conduction between the positive and negative electrodes and forming short circuits, shortening lifespan. Summary of the Invention [Problem to be solved by the invention]

[0003] Typically, positive electrode materials (e.g., graphite) have structural limitations. In other words, attempts to improve the power capacity performance of aluminum batteries result in structural destruction and shortened lifespan. Meanwhile, during the cycle charging and discharging process of aluminum batteries, aluminum plating forms on the negative electrode and continues to grow, forming aluminum dendrites. As the aluminum dendrites continue to grow, they can locally penetrate the separator, causing conduction between the positive and negative electrodes and forming short circuits, shortening lifespan. [Means for solving the problem]

[0004] The present invention provides an aluminum battery that can maintain a longer life and better 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 disposed 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 performs an intercalation mechanism, and the negative electrode performs 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 aqueous electrolyte solution described above contains water and an aluminum salt.

[0008] In one embodiment of the present invention, the weight ratio of the 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-mentioned positive electrode includes a first metal substrate and a first coating layer, the first coating layer being disposed on the first metal substrate and including a metal oxide.

[0010] In one embodiment of the present invention, the weight ratio of the 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-mentioned negative electrode includes a second metal substrate and a second coating layer, the second coating layer being disposed on the second metal substrate and including conjugated organic molecules.

[0012] In one embodiment of the present invention, the conjugated organic molecule includes a compound having 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 of the above-mentioned conjugated organic molecules in the second coating layer is 80 wt % or more and less than 100 wt %.

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

[0015] As described above, the aluminum battery of the present invention uses an aqueous electrolyte, which generates small ions that are less likely to destroy the positive electrode structure, allowing the intercalation mechanism to be effectively implemented, and the chelation mechanism performed by these small ions at the negative electrode replaces the electrochemical mechanism, thereby avoiding the formation of aluminum dendrites, thereby extending the battery life and maintaining better power capacity performance.

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

[0017] [Figure 1] 1 is a structural schematic diagram of an aluminum battery according to one embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing the results of a power capacity test in an example and a comparative example. [Figure 3] FIG. 1 is a schematic diagram showing the results of a life test in an example and a comparative example. 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] 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, an aluminum battery 100 includes a positive electrode 110, a negative electrode 120, a separator 130, and an aqueous electrolyte solution 140. The separator 130 is disposed between the positive electrode 110 and the negative electrode 120, and the aqueous electrolyte solution 140 is impregnated into the separator 130, the positive electrode 110, and the negative electrode 120.

[0023] Furthermore, when the aluminum battery 100 is in operation, the positive electrode 110 performs an intercalation mechanism, and the negative electrode 120 performs a chelation mechanism. Therefore, the aluminum battery 100 of this embodiment uses an aqueous electrolyte 140, which generates small ions that are less likely to destroy the structure of the positive electrode 110, allowing the intercalation mechanism to be performed effectively. The chelation mechanism performed by these small ions in the negative electrode 130 replaces the electrochemical mechanism, preventing the formation of aluminum dendrites. This allows for a longer battery life and better power capacity performance.

[0024] For example, in current aluminum battery configurations, the positive electrode typically uses graphite material and the electrolyte is composed of aluminum chloride and an ionic liquid. In this configuration, the positive electrode's operating mechanism is AlCl4 - (The size is about 0.5 nanometers) It performs an intercalation reaction with ions and stores electric charge. That is, its operating mechanism is AlCl4 - It is based on the insertion of ions into the gaps (interlayer voids) of the layered structure of graphite. However, during the insertion, AlCl4 - The size of the ions is larger than the interlayer distance of graphite (e.g., 0.335 nanometers), which causes structural destruction during the cycling charge-discharge process of aluminum batteries, resulting in poor operational stability. Meanwhile, aluminum plating, which forms aluminum dendrites, is generated based on the electrochemical mechanism of the negative electrode. When aluminum dendrites penetrate the separator and contact the positive electrode, an additional electron path is created, shorting the battery.

[0025] To solve the above-mentioned 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 conjugated organic molecules (which can attract positively charged active materials by carrying a negative charge). In addition, the aqueous electrolyte 140 contains water and aluminum salt (which generates aluminum ions (Al 3+ ) can produce small-sized intercalation active materials such as AlCl4 - In this way, the structural stability of the metal oxide can be utilized to improve the power capacity retention rate during cycle charging and discharging of the aluminum battery 100, and the conjugated organic molecules and the active material (Al) in the electrolyte can be effectively used. 3+ ) (which can be called a chelate structure, rather than a physical intercalation mechanism) can be used to enable the aluminum battery 100 to effectively charge and discharge with a high power capacity, but the present invention is not limited thereto.

[0026] Furthermore, since the aluminum battery 100 of this embodiment does not produce dendrites, a thinner separator 130 can be used, thereby improving the volumetric energy density. 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 preparing the corresponding components into a slurry form using an appropriate method, applying them onto 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 solids content in the slurry of the first coating layer 112 is between 20 wt% and 40 wt% of the solids content of the entire slurry, and the total solids content in the slurry of the second coating layer 122 is between 5 wt% and 30 wt% of the solids content of the entire slurry, although the present invention is not limited thereto.

[0029] In some embodiments, the surface density (coating weight per area) of the coating surface of the first coating layer 112 is in the range of 5 mg / cm 2 ~10mg / cm 2 The surface density (coating weight per area) of the coating surface of the second coating layer 122 is in the range of 0.5 mg / cm 2 ~10mg / cm 2 However, the present invention is not limited thereto.

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

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

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

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

[0035] In some embodiments, the metal oxide comprises vanadium trioxide (V2O3), although the 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 being between 5 wt% and 10 wt%, the weight ratio of the adhesive in the first coating layer 112 being between 8 wt% and 10 wt%, and the total weight ratio of the metal oxide, conductive carbon material, and adhesive being 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 (e.g., carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), or a mixture thereof).

[0037] In some embodiments, the weight ratio of the conjugated organic molecules in the second coating layer 122 is 80 wt % or more and less than 100 wt %, although 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 being between 8 wt% and 10 wt%, the weight ratio of the adhesive in the second coating layer 122 being between 8 wt% and 15 wt%, and the total weight ratio of the conjugated organic molecules, the conductive carbon material, and the adhesive being 100 wt%, but the present invention is not limited thereto. Here, the conductive carbon material may include conductive carbon black, graphene, graphene oxide, or carbon nanotubes (CNTs), and the adhesive may include 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 having 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. For example, the compound having an acid anhydride structure includes perylenetetracarboxylic dianhydride (PTCDA, CAS no: 128-69-8), and the derivative of the acid anhydride structure includes 3,4,9,10-perylenetetracarboxylic diimide (PTCDI, CAS no: 81-33-4), N,N'-dimethyl-3,4,9,10-perylene dicarboximide (MePTC, CAS no: 5521-31-3), or anthraquinone. Composites of compounds having an acid anhydride structure and carbon materials include a composite of perylene tetracarboxylic dianhydride and carbon nanotubes (CNTs), a composite of perylene tetracarboxylic dianhydride and activated carbon (AC), and a composite of perylene tetracarboxylic dianhydride and graphene oxide (GO). Composites of derivatives of an acid anhydride structure and carbon materials include a composite of 3,4,9,10-perylene tetracarboxylic diimide and carbon nanotubes (CNTs), a composite of 3,4,9,10-perylene tetracarboxylic diimide and activated carbon (AC), and a composite of 3,4,9,10-perylene tetracarboxylic diimide and graphene oxide (GO), but the present invention is not limited thereto. Here, a derivative of an acid anhydride structure is defined as a conjugated organic compound or polymer having an acid anhydride structure or a similar acid anhydride.

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

[0041] In some embodiments, the thickness of the first coating layer 121 ranges from 100 micrometers to 120 micrometers, and the thickness of the second coating layer 122 ranges from 10 micrometers to 200 micrometers. For example, if the thickness of the second coating layer 122 exceeds 250 micrometers, the electrodes are easily damaged. Therefore, the second coating layer 122 has better operability when the thickness is 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 needs, and the present invention is not limited thereto.

[0042] In some embodiments, the material of separator 130 includes fiberglass or the like, although the invention is not limited thereto.

[0043] 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.

[0044] <Comparative Example 1>

[0045] Nickel foil was used as the metal substrate for the positive electrode. A slurry (consisting 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) was prepared by a wet mixing method. The slurry was then applied to the nickel foil and dried to form a nickel foil positive electrode with 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 assembled into 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 form the aluminum battery of Comparative Example 1. Here, the wet mixing method is a slurry production method well known to those skilled in the art, in which the above components and a solvent (N-methylpyrrolidone, NMP) are stirred and dispersed, and therefore a detailed description thereof will be omitted here.

[0046] Example 1

[0047] A second slurry (80 wt% vanadium trioxide, 10 wt% conductive carbon black (super P), and 10 wt% adhesive (polyvinylidene fluoride (PVDF))) was prepared by wet mixing and then applied to titanium foil (metal substrate) to a thickness of 250 micrometers using a square applicator. It was then dried at 100 °C for 1 hour to form a coating layer (70 micrometers thick) for the cathode. Next, a third slurry (56 wt% perylene tetracarboxylic dianhydride (PTCDA), 24% graphene oxide (GO), 10 wt% conductive carbon black, and 10 wt% polyvinylidene fluoride (PVDF)) was prepared by wet mixing and then applied to titanium foil (metal substrate) to form a coating layer (45.2 micrometers thick) for the anode. Thereafter, the second slurry was assembled into a CR20232-type coin battery 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, the second slurry contained water as a solvent, and was mixed with zirconia balls and rotary-pulverized in a container using a rotary centrifuge method to improve the uniform dispersion of the materials in the second slurry.

[0048] <Example 2>

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

[0050] Example 3

[0051] The aluminum battery of Example 3 was manufactured using a method similar to that of Example 1, except that the third slurry contained 80 wt% 3,4,9,10-perylenetetracarboxydiimide (PTCDI), 10 wt% conductive carbon black, 1.88 wt% sodium carboxymethylcellulose (CMC), and 8.12 wt% styrene butadiene rubber (SBR), and the thickness of the negative electrode was 58.3 micrometers.

[0052] Example 4

[0053] The aluminum battery of Example 4 was manufactured using a method similar to that of Example 1, except that the third slurry contained 56 wt% 3,4,9,10-perylenetetracarboxydiimide (PTCDI), 24 wt% graphene oxide (GO), 10 wt% conductive carbon black, and 10 wt% polyvinylidene fluoride (PVDF), and the thickness of the negative electrode was 22.5 micrometers.

[0054] Fig. 2 is a schematic diagram showing the results of a power capacity test for the example and the comparative example. Fig. 3 is a schematic diagram showing the results of a life test for the example and the comparative example. 2 and 3 show tests performed using chronopotentiometry (charging / discharging a battery at a constant current, and setting the cutoff potential conditions for switching from charge to discharge / discharge to charge; this constant current is typically a multiple of the weight of VO in the positive electrode coating layer; in this application, this multiple is 0.26. For example, when the positive electrode coating layer contains 1 g of VO, the current value is 0.26 A, setting the cutoff potential; charging the battery with a constant current up to 1.8 V, then switching to discharge; discharging the battery down to 0.1 V, then switching back to charge; repeating this cycle once, the coulombic efficiency is calculated as the ratio of the discharge capacity to the charge capacity for that cycle). The coulombic efficiency was calculated by dividing the discharge capacity by the charge capacity; and the number of cycles during the charge / discharge process at which the coulombic efficiency exceeded 80% was used as the criterion for determining the battery's lifespan.

[0055] The test results are shown in Figures 2 and 3, and the conclusions are as follows: As shown in Figures 2 and 3, the use of an acid anhydride-based material as the negative electrode (PTCDI-based material or anthraquinone) in combination with a metal oxide (VO) positive electrode and an Al(OTf) electrolyte significantly improved the battery's power capacity performance. The average power capacity of the battery increased from 63.3 mAh / g to 157.2 mAh / g (the highest capacity in Example 4), improving the power capacity performance by 2.4 times. The average lifespan of the aluminum battery increased from 49 cycles to 357 cycles, extending the lifespan by 7.2 times. Therefore, the aluminum battery of the present invention reliably extended its lifespan and maintained superior power capacity performance through the synergistic effects of the intercalation mechanism positive electrode, chelating mechanism negative electrode, and aqueous electrolyte.

[0056] As described above, the aluminum battery of the present invention uses an aqueous electrolyte, which generates small ions that are less likely to destroy the positive electrode structure, allowing the intercalation mechanism to be effectively implemented, and the chelation mechanism performed by these small ions at the negative electrode replaces the electrochemical mechanism, thereby avoiding the formation of aluminum dendrites, thereby extending the battery life and maintaining better power capacity performance.

[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 of the present invention can be applied to the aluminum battery field. [Explanation of symbols]

[0059] 100 Aluminum Batteries 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. An aluminum battery, a positive electrode including a first metal substrate and a first coating layer, the first coating layer being provided on the first metal substrate, the first coating layer including a metal oxide; a negative electrode; a separator disposed between the positive electrode and the negative electrode; an aqueous electrolyte solution impregnated in the separator, the positive electrode, and the negative electrode; wherein, when the aluminum battery is in operation, the positive electrode implements an intercalation mechanism, the negative electrode implements a chelation mechanism, and the active material of the aqueous electrolyte solution is aluminum ions.

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

3. 3. The aluminum battery according to claim 2, 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 the water and the aluminum salt is 100 wt %.

4. 2. The aluminum battery according to claim 1, wherein the weight ratio of the metal oxide in the first coating layer is 80 wt % or more and less than 100 wt %.

5. 2. The aluminum battery according to claim 1, wherein the negative electrode comprises a second metal substrate and a second coating layer, the second coating layer being provided on the second metal substrate, and the second coating layer comprising conjugated organic molecules.

6. The aluminum battery according to claim 5, wherein the conjugated organic molecule comprises a compound having an acid anhydride structure, a derivative of the acid anhydride structure, a composite of the compound having the acid anhydride structure and a carbon material, or a composite of the derivative of the acid anhydride structure and a carbon material.

7. 6. The aluminum battery according to claim 5, wherein the weight ratio of the conjugated organic molecules in the second coating layer is 80 wt % or more and less than 100 wt %.

8. 2. The aluminum battery according to claim 1, wherein the separator has a thickness between 200 micrometers and 500 micrometers.

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