Energy storage material and method for manufacturing energy storage material

Abstract

This invention provides an energy storage material and a method for manufacturing the energy storage material that utilize amorphous alumina, which can be manufactured in relatively large sizes and reduce manufacturing costs. [Solution] The substrate is made of an aluminum alloy containing Mn, and a thin film containing amorphous alumina is placed on the surface of the substrate. The thin film has a plurality of irregularities on its surface. Preferably, the irregularities have a diameter of 1 nm to 50 nm. Preferably, the amorphous alumina is made of AlO6 clusters having atomic vacancies.

Description

[Technical Field]

[0001] This invention relates to an energy storage material and a method for manufacturing the energy storage material. [Background technology]

[0002] Capacitors are electronic components that store and discharge electric charge (electrical energy) through their capacitance. For example, in mobile electronic devices such as personal computers and mobile phones, they play roles such as power supply stability, backup circuits, coupling elements, and noise filters, making them indispensable components for electronic devices. In recent years, high-performance IT products such as mobile phones and ultra-small memory devices, as well as batteries for electric vehicles, have evolved rapidly, leading to increased demand for capacitors that are even smaller, have higher capacity, and possess advanced functions such as memory. In particular, there is a demand for products that are compatible with smart grids (next-generation power transmission networks) and align with green innovation (low-carbonization) to combat global warming. For example, the market for automobiles, IT equipment, energy-saving inverters, and capacitors has been steadily expanding at an average annual rate of approximately 3.7% in recent years, and has already reached a market size of 1 trillion yen.

[0003] Such capacitors should ideally not contain flammable elements like lithium or environmental pollutants, and should be made of solid rather than liquid. In other words, there is a need for materials that are harmless to health and inexpensive.

[0004] Capacitors are broadly classified into two types based on their application: those for high-voltage power circuits (heavy electrical equipment) and those for electronic and electrical equipment circuits (low-voltage). Of these, ceramic capacitors are primarily used for electronic and electrical equipment circuits in the low-voltage sector, and secondary batteries are also widely used for storing electricity in mobile phones and other devices. In contrast, capacitors for heavy electrical equipment applications have not yet been put into practical use due to insufficient voltage resistance and storage capacity.

[0005] Capacitors using conventional lumped-parameter circuits are widely used as major components in electronic and electrical equipment, ranging from 1 pF to several tens of mF. The storage capacity C(F) is: C = Q / V = ε × (A / d) (Here, Q: charge, V: voltage, ε: dielectric constant, A: electrode area, d: distance between electrodes) As given by , the larger the electrode area A and the smaller the distance between electrodes d, the higher the charge capacitance. However, from the standpoint of miniaturizing electronic and electrical equipment and the required energy storage capacity, it is difficult to increase the electrode area A and decrease the distance between electrodes d to achieve extremely high capacitance, or to decrease the electrode area A and increase the distance between electrodes d to achieve extremely low capacitance. Furthermore, the capacitance of dielectric capacitors using current lumped-parameter circuits has already reached saturation.

[0006] One energy storage method that surpasses conventional electrical capacities is the use of electrically distributed constant circuits. For example, electric double-layer capacitors, which consist of activated carbon moistened with an electric field solution, have recently been put into practical use. However, solid-state electric double-layer capacitors are not yet in use.

[0007] Regarding solid energy storage materials, the present inventors have discovered that Si-(Al,Ti,V) alloys in which Al,Ti,V have been surface-extracted and removed, as well as TiO2-coated Ti-Ni-Si and Al2O3-coated Al-Y amorphous alloys, can store charge regardless of whether it is DC or AC (see, for example, Non-Patent Documents 1 to 11 and Patent Documents 1 to 4).

[0008] Furthermore, the inventors have discovered that when the size of compound particles is 40 nm or less, preferably 10 nm or less, a "quantum size effect" occurs due to electron shielding on the nano-sized solid surface. The inventors have developed energy storage materials that utilize this phenomenon, in which nano-sized irregularities are formed on the surface of amorphous titania, amorphous alumina, amorphous fluoropolymer, and amorphous cellulose nanofiber (see, for example, Non-Patent Documents 4, 7 to 11, and Patent Documents 1 to 4). In these energy storage materials, due to the quantum nano-size effect, the smaller the diameter of the protrusions becomes in the nanoscale, the more the van der Waals electrostatic force acts at a power of minus 6 of the diameter of the protrusions, increasing the electron adsorption capacity to the protrusions (see, for example, Non-Patent Document 7). The work function, which is an indicator of the magnitude of electron adsorption capacity, was -5.5 eV for amorphous titania (see, for example, Non-Patent Document 7) and -10.3 eV to -13.35 eV for amorphous fluoropolymers (see, for example, Non-Patent Document 4 and Patent Document 2).

[0009] Furthermore, the present inventors have developed an energy storage material with a larger work function (-20.4 eV) than these energy storage materials, enabling large-capacity energy storage. This material has an amorphous surface mainly composed of AlO6 clusters and has multiple irregularities with a diameter of 0.1 to 50 nm and a height difference of 0.1 to 50 nm (see, for example, Non-Patent Document 12). [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] M. Fukuhara, T. Araki, K. Nagayama and H. Sakuraba, “Electric storage in de-alloyed Si-Al alloy ribbons”, EuroPhys. Lett., 2012, 99 ,47001 [Non-Patent Document 2] M. Fukuhara, “Electric Charging / Discharging Characteristics of Capacitor, Using De-alloyed Si-20Al Alloy Ribbons”, Elect. Electr. Eng., 2013, 3(2), pp.72-76 [Non-Patent Document 3] M. Fukuhara and H. Yoshida, “AC charging / discharging of de-alloyed Si-Al-V alloy ribbons”, J. Alloys and Comp., 2014, 586, S130-S133 [Non-Patent Document 4] M. Fukuhara, H. Yoshida, M. Sato, K. Sugawara, T. Takeuchi, I. Seki, and T. Sueyoshi, “Superior electric storage in de-alloyed and anodic oxidized Ti-Ni-Si glassy alloy ribbons”, Phys. Stat. Sol. RRL, 2013, 7(7), pp.477-480 [Non-Patent Document 5] M. Fukuhara and K. Sugawara, “Electric charging / discharging characteristics of super capacitor, using de-alloying and anodic oxidized Ti-Ni-Si amorphous alloy ribbons”, Nanoscale. Res. Lett., 2014, 9, p.253 [Non-Patent Document 6] M. Fukuhara and K. Sugawara, "Anodic oxidization of Ti-Ni-Si amorphous alloy ribbons and their capacitive and resistive properties", Thin Solid Films, 2015, 595, p.1-4

Non-licensed Document 7

Non-licensed literature 9

Non-licensed literature 10

Non-licensed Document 11

[0011] [Patent Document 1] Japanese Patent No. 6498945 Publication [Patent Document 2] Japanese Patent No. 6628241 Publication [Patent Document 3] Japanese Patent No. 7057577 Publication [Patent Document 4] Japanese Patent No. 6839386 Publication [Summary of the Invention] [Problems to be Solved by the Invention]

[0012] For example, the energy storage material using amorphous alumina described in Non-Patent Document 12 is capable of storing relatively large amounts of energy. However, conventional energy storage materials using amorphous alumina described in Non-Patent Documents 9, 12, and Patent Document 4 have the limitation that the starting material must be an amorphous aluminum alloy. Furthermore, since rapid cooling and solidification from molten metal is an essential condition for producing the amorphous aluminum alloy, there is a problem in that it is difficult to produce relatively large sizes of 1 cm or more in width. In addition, there is a problem in that the manufacturing cost is high because the equipment used for rapid cooling and solidification is large in scale.

[0013] This invention addresses these challenges and aims to provide an energy storage material using amorphous alumina and a method for manufacturing the energy storage material, which can be manufactured in relatively large sizes and reduce manufacturing costs. [Means for solving the problem]

[0014] Based on the finding that when a trace amount of Mn is present relative to Al, the oxidation of that trace Mn component is suppressed during anodizing, the inventors discovered that by anodizing a commercially available crystalline aluminum alloy containing Mn, the amorphous oxide film on the surface increases, and nano-sized irregularities are formed, resulting in high energy storage capacity as a solid energy storage material, leading to the present invention.

[0015] In other words, the energy storage material according to the present invention comprises a substrate made of an aluminum alloy containing Mn, and a thin film containing amorphous alumina on the surface of the substrate, wherein the thin film has a plurality of irregularities on its surface.

[0016] The energy storage material according to the present invention has a thin film containing amorphous alumina on the surface of the substrate, which has multiple irregularities on its surface. Therefore, it can exhibit energy storage properties due to a physical electron adsorption phenomenon caused by the minus-6th power quantum size effect occurring on the protrusions of these irregularities. Furthermore, by utilizing this electron adsorption ability, energy storage and discharge can be performed. Additionally, since each irregularity on the thin film surface acts as a capacitor consisting of a solid / gas electric double layer, the overall electrical circuit of the thin film surface becomes an electrically distributed constant circuit with multiple capacitors connected in finite parallel connections, thus forming a large-capacity energy storage body. This also enables instantaneous or relatively short-term energy storage.

[0017] In the energy storage material according to the present invention, if the capacitance of each individual capacitor in each protrusion is c and the number of protrusions is n, then the total amount of stored energy C can be expressed as n × c, as shown in equation (1).

number

[0018] The method for manufacturing an energy storage material according to the present invention is characterized by forming a thin film containing amorphous alumina on the surface of a crystalline aluminum alloy containing Mn by anodizing the alloy, and forming a plurality of irregularities. In particular, it is preferable to manufacture the energy storage material according to the present invention by the anodizing method.

[0019] According to the method for manufacturing energy storage materials of the present invention, commercially available crystalline aluminum alloys can be used as raw materials. Furthermore, since it can be manufactured by anodizing and rapid solidification is unnecessary, it can be manufactured using, for example, commercially available large crystalline aluminum alloy sheets with an area of ​​10 cm x 10 cm or more. Thus, the energy storage material according to the present invention can be manufactured in a relatively large size using the method for manufacturing energy storage materials according to the present invention, thereby reducing manufacturing costs. In addition, this enables mass production and promotes industrialization.

[0020] The energy storage material according to the present invention preferably contains a crystalline aluminum alloy with Mn as the raw material, which contains 95 wt% or more Al and 0.3 wt% to 2.5 wt% Mn. In this case, a thin film containing amorphous alumina with higher energy storage capacity can be produced by anodizing. Furthermore, in this case, the substrate has the same composition as the raw material, containing 95 wt% or more Al and 0.3 wt% to 2.5 wt% Mn.

[0021] In the energy storage material according to the present invention, the thin film preferably contains 35% or more of amorphous alumina, and more preferably 80% or more. Furthermore, the thin film preferably contains 65% or less of crystalline alumina compound, and more preferably 20% or less.

[0022] In the energy storage material according to the present invention, the amorphous alumina is preferably composed of AlO6 clusters having atomic vacancies. In this case, the AlO6 has a structure in which Al and a portion of the oxygen are doubly deficient, and lone electrons can be generated around these atomic vacancies by quantum effects. At this time, a positive charge is induced inside the amorphous alumina by electrostatic induction by these lone electrons, and as a result, electrons from the outside can be adsorbed. As a result, the amorphous alumina thin film has a very large work function, and high energy storage capacity is obtained. Furthermore, even if the amount of adsorbed charge on the surface increases due to the positive charge in the amorphous alumina, the electrical neutrality is maintained by the positive charge, so dielectric breakdown can be avoided.

[0023] In the energy storage material according to the present invention, the plurality of irregularities preferably have a diameter of 1 nm to 50 nm. In this case, the quantum size effect occurring in the protrusions of the irregularities can be effectively manifested. Furthermore, in order to make the quantum size effect more effective and exhibit even higher energy storage capacity, the diameter of the irregularities is more preferably 1 nm to 30 nm.

[0024] The energy storage material according to the present invention has an electrical resistivity of 10 2 ~10 8It is a solid electrolyte with a density of Ωcm and an electrical capacitance of 2,500 mJ / m³. 2 Preferably, the above is true. Furthermore, in the energy storage material according to the present invention, the thin film has a specific surface area of ​​2,000 m². 2 It is preferable that the value is 1 / g or higher. In these cases, higher energy storage capacity can be achieved.

[0025] The energy storage material according to the present invention preferably has a thin film thickness of 100 μm or less, and more preferably 50 μm or less, in order to achieve a weight reduction effect. In this case, since static electricity attaches to and detaches from the surface, the power density and energy density can be increased by making the thin film thinner.

[0026] The energy storage material according to the present invention is preferably capable of instantaneous or short-term energy storage of 1 ms to 1 minute, and more preferably capable of long-term discharge of 1 day or more due to its large capacity. Furthermore, the energy storage material according to the present invention preferably has a charge / discharge response characteristic of 1 mHz to 100 kHz, and more preferably 0.1 to 100 Hz.

[0027] An ultra-energy storage device can be constructed by using only the thin film of the energy storage material according to the present invention and providing conductive electrodes on both sides of the thin film so as to sandwich it. Generally, devices with a larger specific surface area than conventional capacitors and formed by an electric double layer energy storage system are called supercapacitors (super energy storage devices), and those with an energy storage capacity three orders of magnitude larger are called ultracapacitors (ultra energy storage devices).

[0028] The ultra-energy storage device according to the present invention is equivalent to a distributed-parameter capacitor having multiple minute capacitors perpendicular to each conductive electrode, corresponding to the number of irregularities in the thin film of the energy storage material. That is, the minute irregularities themselves become high electrical resistance and can be represented by a parallel equivalent circuit of C and R. Furthermore, the ultra-energy storage device according to the present invention can be manufactured by forming each conductive electrode on both the upper and lower surfaces of the thin film using a micro-electromechanical system (MEMS) by sputtering or casting. In this case, it is preferable that each conductive electrode is formed to contact the protrusions along the surface shape of the thin film of the energy storage material. It is preferable that each conductive electrode is made of Al, Cu, gold, polyacetylene, polypyrrole, polyaniline, polythiophene, polyethylenedioxythiophene, polyphenylene, polyfluorene, polyphenylene vinylene, polythienylene vinylene, etc. Furthermore, it is preferable that the ultra-energy storage device according to the present invention is operable at -269°C to 300°C.

[0029] A stacked ultra-energy storage body can be constructed by stacking multiple ultra-energy storage bodies according to the present invention. This stacked ultra-energy storage body according to the present invention can be formed, for example, by stacking ultra-energy storage bodies according to the present invention in parallel using various MEMS methods. As a result, the stacked ultra-energy storage body according to the present invention can be a solid-state quantum direct energy storage body in which each parallel equivalent circuit is coupled in an electrically distributed constant manner. Furthermore, the stacked ultra-energy storage body according to the present invention may consist of a parallel integrator in which multiple thin films of the energy storage material according to the present invention are arranged side by side between a pair of conductive electrodes, along the inner surface of each conductive electrode. In this case, a dielectric strength of 1 GV / m or more can be obtained.

[0030] The ultra-energy storage devices and laminated ultra-energy storage devices according to the present invention can be used, for example, as AC capacitors in microelectronic circuits or as energy storage devices on the back surface of solar panels. They can also be used in various backup power supply modules, coupling elements, noise filters, high-sensitivity acceleration sensors, high-output transformer interruption prevention devices, and electronic and electrical circuit boards such as emergency power supply devices for automobiles or ships. Furthermore, in the future, they are expected to be used as direct DC energy storage devices from sunlight in outer space. [Effects of the Invention]

[0031] According to the present invention, it is possible to provide an energy storage material using amorphous alumina and a method for manufacturing the energy storage material, which can be manufactured in a relatively large size and reduce manufacturing costs. [Brief explanation of the drawing]

[0032] [Figure 1] This is a perspective view showing the molecular structure of an energy storage material according to an embodiment of the present invention. [Figure 2] This is a circuit diagram of an electrical distributed constant circuit showing an energy storage material according to an embodiment of the present invention. [Figure 3] This is an atomic force microscope (AFM) image of the surface of an energy storage material according to an embodiment of the present invention. [Figure 4] This is the XRD spectrum of a thin film of the energy storage material according to an embodiment of the present invention. [Figure 5] This graph shows the relationship between the applied voltage and stored energy in a discharge test of the energy storage material according to an embodiment of the present invention. [Figure 6] This is a Nyquist plot (Cole-Cole plot) of AC impedance showing the frequency characteristics of the energy storage material according to an embodiment of the present invention. [Figure 7](a) to (c) are side views showing a method for fabricating an ultra-energy storage body using a thin film of the energy storage material according to an embodiment of the present invention, (d) is a perspective view of the fabricated ultra-energy storage body, (e) is a side view of a laminated ultra-energy storage body, (e) is a perspective view showing the circuit of the laminated ultra-energy storage body, and (f) is a circuit diagram of the laminated ultra-energy storage body. [Modes for carrying out the invention]

[0033] Embodiments of the present invention will be described below with reference to the drawings and examples. The energy storage material according to an embodiment of the present invention comprises a substrate and a thin film. The substrate is made of an aluminum alloy containing Mn. The thin film contains amorphous alumina and is provided on the surface of the substrate. The thin film has multiple irregularities on its surface.

[0034] As shown in Figure 1, amorphous alumina contained in the thin film consists of AlO6 clusters with atomic vacancies. AlO6 has atomic vacancies in which part of Al is missing (Al-Vac) and atomic vacancies in which part of O is missing (O-Vac), forming a doubly defective structure.

[0035] In the embodiment of the present invention, the energy storage material has a thin film containing amorphous alumina on the surface of the substrate, which has multiple irregularities on its surface. Therefore, it can exhibit energy storage properties due to a physical electron adsorption phenomenon caused by the minus-6th power quantum size effect occurring at the protrusions of these irregularities. Furthermore, because the AlO6 of the amorphous alumina has a structure in which some Al and O atoms are doubly deficient, lone electrons can appear around these atomic vacancies due to quantum effects. At this time, electrostatic induction by these lone electrons induces a positive charge inside the amorphous alumina, resulting in the adsorption of electrons from the outside. As a result, the amorphous alumina thin film has a very large work function, allowing for higher energy storage capacity.

[0036] The energy storage material according to the embodiment of the present invention can store and discharge energy by utilizing the electron adsorption capacity due to the quantum size effect. Furthermore, as shown in Figure 2, each of the irregularities on the thin film surface becomes a capacitor consisting of a solid / gas electric double layer, so the electrical circuit of the entire thin film surface is an electrically distributed constant circuit in which multiple capacitors are joined in parallel in a finite number of places. For this reason, the energy storage material according to the embodiment of the present invention can form a large-capacity energy storage body having the total energy storage amount shown in equation (1) above. In addition, this makes it possible to store energy instantaneously or in a relatively short time.

[0037] The energy storage material according to the embodiment of the present invention can be suitably manufactured by the method for manufacturing the energy storage material according to the embodiment of the present invention. That is, in the method for manufacturing the energy storage material according to the embodiment of the present invention, a crystalline aluminum alloy containing Mn is anodized. As a result, a thin film of amorphous alumina is formed on the surface of the crystalline aluminum alloy, and multiple nano-sized irregularities are formed, so that the energy storage material according to the embodiment of the present invention can be manufactured.

[0038] In this case, commercially available crystalline aluminum alloys can be used as raw materials. Since it can be manufactured by anodizing and rapid solidification is unnecessary, for example, large commercially available crystalline aluminum alloy plates with an area of ​​10 cm x 10 cm or more can be used. Thus, according to the method for manufacturing energy storage materials of the embodiment of the present invention, energy storage materials of the embodiment of the present invention can be manufactured in relatively large sizes, thereby reducing manufacturing costs. Furthermore, this enables mass production and can promote industrialization.

[0039] Furthermore, the following seven conditions can be considered as physical requirements for using solids as energy storage materials. (1) In order to produce the quantum size effect, the surface must be a surface with irregularities of 50 nm or less. (2) The material has a high work function (electron adsorption capacity). (3) The structure has a locally positive charge. (4) The electrical circuit on the surface is a distributed constant circuit (parallel connection) (charge stacking effect) (5) To prevent leakage of stored charge, the electrical resistivity must be 100 Ωcm or more. (6) The surface of amorphous alumina has an electrical resistivity of 10 2 ~10 8 It must be a solid electrolyte with a density of Ωcm. (7) Adsorbed electrons instantaneously form an electric double layer in the solid by protonic solitons

[0040] The energy storage material according to the embodiment of the present invention is thought to satisfy all seven of these conditions and has excellent performance as a solid quantum energy storage material and quantum energy storage body. The following are examples of the energy storage material and the method for manufacturing the energy storage material according to embodiments of the present invention. These examples are provided solely for the purpose of explaining the present invention and as reference for specific embodiments, and are not intended to limit or restrict the scope of the invention disclosed herein. [Examples]

[0041] Energy storage materials were manufactured using the manufacturing method of the embodiment of the present invention. Each of the crystalline aluminum alloys shown in Table 1 was used as the raw material, and energy storage samples 1 to 5 were manufactured under the anodizing treatment conditions shown in Table 1. Note that the surface phase after anodizing crystallizes at charge voltages of 50V or higher or treatment times longer than 60 minutes; therefore, anodizing was performed under conditions of not exceeding 50V and 60 minutes or less.

[0042] [Table 1]

[0043] First, an Al-0.5Mn alloy containing 0.5 at% Mn was used as the raw material, and this raw material was used as the anode. Anodizing was performed using a 0.4 mol / L dilute sulfuric acid solution with pure water. Anodizing was performed at 20-22.5 V and 17-18 mA / cm². 2The treatment was carried out for 60 minutes. After anodization, the anode was taken out and sufficiently washed with water to obtain Sample 1 having a thin amorphous alumina film on the surface.

[0044] Further, an Al-1.0Mn alloy containing 1.0 at% of Mn was used as a raw material, and the same dilute sulfuric acid solution as that for Sample 1 was used, at 21 to 22.8 V, 22.5 to 26.3 mA / cm 2 , anodization was performed for 60 minutes to obtain Sample 2 having a thin amorphous alumina film on the surface. Further, an Al-1.5Mn alloy containing 1.5 at% of Mn was used as a raw material, and the same dilute sulfuric acid solution as that for Sample 1 was used, at 24 to 24.3 V, 21.5 to 30 mA / cm 2 , anodization was performed for 60 minutes to obtain Sample 3 having a thin amorphous alumina film on the surface. Further, an Al-2.0Mn alloy containing 2.0 at% of Mn was used as a raw material, and the same dilute sulfuric acid solution as that for Sample 1 was used, at 25.3 V, 21.3 to 31.3 mA / cm 2 , anodization was performed for 60 minutes to obtain Sample 4 having a thin amorphous alumina film on the surface.

[0045] Further, a commercially available A3003 alloy (Si: 0.6 at%, Fe: 0.7 at%, Cu: 0.05 to 0.20 at%, Mn: 1.0 to 1.5 at%, Zn: 0.1 at%, Al: balance) was used as a raw material, and anodization was performed in a 0.4 mol / L dilute sulfuric acid solution using 50 mg / L carbon dioxide nanobubble water instead of the pure water used for Sample 1. The anodization was carried out at 26 to 31.7 V, 13.2 to 19.2 mA / cm 2 for 60 minutes. After anodization, the anode was taken out and sufficiently washed with water to obtain Sample 5 having a thin amorphous alumina film on the surface.

[0046] For each of the electricity storage materials of Samples 1 to 5, the specific surface area was measured by the BET adsorption method. As a result, all of them had 2,000 m 2It was confirmed that the amount was greater than / g. This is thought to be because, during anodic oxidation, Al first dissolves in dilute sulfuric acid, and then Mn oxide precipitates, resulting in an amorphous oxide with a solid uneven structure. Furthermore, it is thought that this characteristic allows for high energy storage capacity, and as shown in samples 1 to 4, it was confirmed that the energy storage capacity is highest when the amount of Mn in the Al alloy is around 1.0 to 1.5 at%. From this, it is thought that, for example, by using a commercially available A3003 alloy containing 1.5 at% Mn, as shown in sample 5, an energy storage material with high energy storage capacity, low cost, and large shape can be obtained.

[0047] Next, the surfaces of each energy storage material from samples 1 to 5 were observed using an atomic force microscope (AFM). The AFM image of the surface of sample 5 is shown in Figure 3. As shown in Figure 3, it was confirmed that the surface of the energy storage material of sample 5 had countless irregularities with a diameter of 30 nm or less. In addition, it was confirmed that the surface of the energy storage material of sample 1 had countless irregularities with a diameter of approximately 35 nm, and the surfaces of the energy storage materials of samples 2 to 4 had countless irregularities with a diameter of 50 nm or less.

[0048] Furthermore, the thickness of the amorphous alumina thin film of each energy storage material was determined from the AFM images of samples 1 to 5 and is shown in the thickness column of Table 1. As shown in Table 1, it was confirmed that the thin films of each energy storage material in samples 1 to 5 had a thickness of 35 μm to 60 μm.

[0049] Next, X-ray diffraction (XRD) analysis was performed on the thin films of each energy storage material, samples 1 to 5. The XRD spectrum of sample 5 is shown in Figure 4. As shown in Figure 4, the XRD spectrum of sample 5 shows a generally smooth curve, confirming that it mainly consists of an amorphous phase. In addition, peaks due to the crystalline phases of the α and γ phases were confirmed within the curve. Analysis of the XRD spectrum shown in Figure 4 confirmed that sample 5 contains 15% crystalline (α, γ) phase within the amorphous phase. Similarly, the results of the analysis of the XRD spectra of samples 1 to 4 are shown in the crystallinity column of Table 1. As shown in Table 1, it was confirmed that the thin films of each energy storage material, samples 1 to 5, contain 15 to 65% crystalline (α, γ) phase within the amorphous phase.

[0050] Next, discharge tests were performed on the thin films of each energy storage material, samples 1 to 5. In the test, the films were first charged to 500V for 1 second using the constant voltage method, and then discharged at a constant current (10μA) using the constant current discharge method. The energy storage capacity was determined from the voltage change and discharge time during discharge and is shown in the energy storage capacity column of Table 1. As shown in Table 1, the thin films of each energy storage material, samples 1 to 5, had energy storage capacities ranging from 2,780 to 6,600 mJ / m². 2 This was confirmed. Furthermore, it was confirmed that each of the energy storage materials from samples 1 to 5 can operate from -269°C to 300°C and up to 500V. In particular, it was confirmed that sample 5 had improved energy storage capacity due to the effect of suppressing Al oxidation in water by carbon dioxide nanobubble water, and its withstand voltage was also improved up to 1,000V.

[0051] Figure 5 shows the relationship between applied voltage and stored energy in a discharge test on a thin film of the energy storage material of sample 5. As shown in Figure 5, it was confirmed that the amount of stored energy increased with increasing applied voltage, and the amount of increase also increased. From these results, it can be said that the energy storage material of the embodiment of the present invention can be charged in a short time (or instantaneously) compared to conventional electrochemical batteries that require a long time of 1 to 8 hours for charging. For this reason, it is considered that the energy storage material of the embodiment of the present invention is particularly effective when used in heavy electrical or stationary energy storage devices.

[0052] Next, the frequency characteristics of the thin films of each energy storage material (samples 1-5) were measured. The measurements were performed by mechanically fixing Al electrodes above and below each thin film of each energy storage material. AC impedance was measured in the frequency range of 1 mHz to 1 GHz using a potentiostat / galvanostat. From the measurement results, a Nyquist plot (Cole-Cole plot) of AC impedance was created, and the electrical resistivity was determined. The results are shown in the electrical resistivity column of Table 1. As shown in Table 1, the electrical resistivity of the thin films of each energy storage material (samples 1-5) is 5 × 10⁻⁶. 4 ~7×10 7 It was confirmed to be Ωcm.

[0053] The Nyquist plot of sample 5 is shown in Figure 6. The thin film of energy storage material used in the measurement of sample 5 has a surface area of ​​12 mm × 15 mm. As shown in Figure 6, it was confirmed that it has a portion parallel to the imaginary axis (-Im(Z) axis). Since such AC impedance characteristics are due to the electrically distributed constant circuit shown in Figure 2, in which countless capacitors are connected in parallel to a resistor R, the thin film of energy storage material of sample 5 can be said to be one giant energy storage body.

[0054] Table 2 shows the characteristics of the energy storage material according to the embodiment of the present invention, compared with the characteristics of commercially available Li-ion batteries, electric double-layer capacitors, and physical secondary batteries (Battenice). In Table 2, "○" indicates relatively good characteristics, "×" indicates relatively poor characteristics, and "△" indicates average characteristics. As shown in Table 2, the energy storage material according to the embodiment of the present invention has superior characteristics compared to Li-ion batteries, particularly in terms of charging voltage, operating temperature, charging time, DC energy storage, fire resistance, and environmental pollution; superior characteristics compared to electric double-layer capacitors, particularly in terms of charging voltage, operating temperature, fire resistance, and environmental pollution; and superior characteristics compared to physical secondary batteries, particularly in terms of charging voltage, operating temperature, and DC energy storage.

[0055] [Table 2]

[0056] The energy storage material according to the embodiment of the present invention can be charged in a short time, and it is thought that the current obtained by converting 50Hz and 60Hz alternating current to direct current using the AC / DC converter of a generator can be stored every 50 / 1000 to 60 / 1000 seconds. For this reason, the energy storage material according to the embodiment of the present invention can be transported without relying on power lines and can be freely transported domestically and internationally not only by automobile but also by ship, airplane, etc.

[0057] As shown in Figure 7, an ultra-energy storage body 20 and a stacked ultra-energy storage body were fabricated using a thin film of the energy storage material from sample 2 by MEMS. First, a Cu layer (thickness 500 nm) 22 was formed on the surface of a glass substrate (40 × 40 × 500 μm) 21 by sputtering (see Figure 7(a)), a thin film 11 of the energy storage material from sample 2 was placed on top of it (see Figure 7(b)), and then an Al layer (thickness 500 nm) 23 was sputtered on top of that (see Figures 7(c) and (d)). The glass substrate 21 was removed to form a single ultra-energy storage body 20. At this time, the Cu layer 22 and the Al layer 23 form a pair of metal electrodes.

[0058] Next, a stacked ultra-energy storage body 30 was fabricated by stacking multiple ultra-energy storage bodies 20 (see Figure 7(e)). In the fabricated stacked ultra-energy storage body 30, the ultra-energy storage bodies 20 are joined in parallel, with the top Al layer 23 and the bottom Cu layer 22 serving as terminals (see Figures 7(f) and (g)). Therefore, for example, a stacked ultra-energy storage body 30 made by stacking 100 ultra-energy storage bodies 20 has 100 times the capacity of a single ultra-energy storage body 20.

[0059] The ultra-energy storage bodies and laminated ultra-energy storage bodies according to embodiments of the present invention can be used, for example, as AC capacitors in microelectronic circuits or as energy storage bodies on the back surface of solar panels. They can also be used in various backup power supply modules such as those for lightning arresters, welding, and over-discharge prevention, as well as in coupling elements, noise filters, high-sensitivity acceleration sensors, high-output transformer interruption prevention devices, and electronic and electrical circuit boards such as emergency power supply devices for automobiles or ships. Furthermore, in the future, they are expected to be used as direct DC energy storage bodies from sunlight in outer space. [Explanation of symbols]

[0060] 11 (Thin film of energy storage material) 20 Ultra Energy Storage 21 Glass substrate 22 Cu layer 23 Al layer 30-layer ultra-energy storage

Claims

1. A substrate made of an aluminum alloy containing Mn, The substrate has a thin film containing amorphous alumina on its surface, The thin film has a plurality of irregularities on its surface. A distinctive energy storage material.

2. The energy storage material according to claim 1, characterized in that the thin film contains 80% or more of the amorphous alumina.

3. The amorphous alumina is AlO having atomic vacancies. ６ The energy storage material according to claim 1, characterized in that it consists of clusters.

4. The energy storage material according to claim 1, characterized in that the plurality of irregularities have a diameter of 1 nm to 50 nm.

5. Electrical resistivity is 10 ２ ~10 ８ It is a solid electrolyte with a capacitance of 2,500 mJ / m³. ２ The energy storage material according to claim 1, characterized in that it is as described above.

6. The thin film has a specific surface area of ​​2,000 m². ２ The energy storage material according to claim 1, characterized in that it is 1 g or more.

7. The energy storage material according to claim 1, characterized in that the substrate contains 95 wt% or more of Al and 0.3 wt% to 2.5 wt% of Mn.

8. A method for manufacturing an energy storage material, characterized by forming a thin film containing amorphous alumina on the surface of a crystalline aluminum alloy containing Mn by anodizing the alloy, and forming multiple irregularities.

9. The method for producing an energy storage material according to claim 8, characterized in that the energy storage material according to any one of claims 1 to 7 is produced by the aforementioned anodizing.

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