Semiconductor electricity storage material, electricity storage body, layered electricity storage body

Abstract

[Problem] To provide: a semiconductor electricity storage material formed from a bio-material and having semiconductor properties and electricity storage properties; an electricity storage body; and a layered electricity storage body. [Solution] The present invention has fibers containing chitin or chitosan as the primary component, is in the form of a sheet, and has a density of 2 g / cm3 or less. Preferably the fibers are crystallized or amorphous fibers. Preferably the fibers are chitosan nanofibers having a width of 3 to 400 nm, or are formed from bundles or particle-like aggregates of chitosan fibers. Preferably the semiconductor is an n-type bulk semiconductor and preferably has N-type negative resistance.

Description

Semiconductor energy storage material, energy storage body, and laminated energy storage body

[0001] The present invention relates to a semiconductor electricity storage material, an electricity storage unit, and a stacked electricity storage unit.

[0002] Semiconductors are electronic components used in low-voltage devices such as transistors, taking advantage of their property of significantly changing conductivity in response to the introduction of impurities or the influence of heat, light, magnetic fields, voltage, current, and radiation. They are essential components for electronic devices. Semiconductors are widely used in various diodes, transistors, FETs, SITs, RAMs, ROMs, CCDs, and other devices. In recent years, high-performance IT products such as mobile phones and ultra-compact storage devices, as well as batteries for electric vehicles, have rapidly evolved, increasing the demand for semiconductors that are even smaller, have larger capacities, and offer advanced functions such as memory. In particular, there is a demand for products that are compatible with a smart grid (next-generation power transmission network) society, which is in line with green innovation (low-carbonization) aimed at preventing global warming. For example, the market for capacitors, used in automobiles, IT devices, energy-saving inverters, and other applications, has steadily expanded at an average annual rate of approximately 3.7%, reaching a 1 trillion yen market size.

[0003] Traditionally, inorganic and organic materials have been used as semiconductor materials. However, these are all artificial, and many of them are harmful to the global environment and the survival of living organisms, including humans. For this reason, it is desirable for semiconductor materials to be free of toxic elements such as arsenic, lead, cadmium, beryllium, and mercury, as well as environmental pollutants such as lithium, chromium, and sulfur. In other words, there is a demand for inexpensive semiconductor materials that are harmless to health.

[0004] Semiconductors are broadly classified into those for high-voltage power circuits (heavy electrical) and those for electronic / electrical equipment circuits (low-voltage). Silicon and compound semiconductors are primarily used as the main semiconductor materials for low-voltage electronic / electrical equipment circuits. For example, the inventors of the present invention have developed a metal / semiconductor transistor made of an amorphous Ni-Nb-Zr-H alloy (see, for example, Non-Patent Documents 1 to 5 or Patent Document 1). Organic semiconductors are also widely used as materials for organic electroluminescence (EL) and organic solar cells, which are key components in televisions and smartphones.

[0005] Some organic semiconductor components cause an increase in carbon dioxide gas and become microplastics that cause marine pollution, and the manufacture of such components is being avoided worldwide from the perspective of protecting animals and plants and preserving the global environment. From this perspective, developing semiconductors using wood and plant fiber (cellulose) obtained from plants, which have a low environmental impact in terms of production and disposal, are lightweight, and have high elasticity, is a timely direction for preserving the global environment.

[0006] Conventionally, semiconductors made from carbon-neutral biomaterials have not been used. However, by focusing on the use of environmentally friendly, recyclable plant fibers, the present inventors have discovered n-type semiconductors made from the non-wood annual plant kenaf and coniferous trees, which are representative of wood. DC / AC devices, insulator / metal conduction switching devices, rectifying biomaterials, and room-temperature transistors have been developed using fiber materials of cellulose molecules obtained from wood and plant fibers (pulp) (see, for example, Non-Patent Document 6).

[0007] On the other hand, a capacitor is an electronic component that originally stores and discharges electric charge (electrical energy) by electrostatic capacitance, and is an essential component for mobile electronic devices such as personal computers and mobile phones, playing roles such as power supply stability, backup circuits, coupling elements, and noise filters. In recent years, high-performance IT products such as mobile phones and ultra-compact storage devices, as well as batteries for electric vehicles, have rapidly evolved, and there has been an increasing demand for capacitors that are even smaller, have large capacities, and have high functionality such as memory.

[0008] Conventional capacitors are made of materials such as amorphous titania, amorphous alumina, and amorphous polymers, and are characterized by having an electrically insulating uneven surface (see, for example, Non-Patent Documents 7 to 15). However, all of these are artificial, and the use of capacitors using harmful compounds such as Li and Pb is undesirable from the perspective of protecting the global environment. In contrast, by focusing on the use of recyclable plant fibers, the present inventors discovered that TEMPO-oxidized cellulose nanofibers (CNF) made from coniferous biomaterials exhibit a powerful electricity storage effect. Energy storage materials and ultra-electrical storage devices capable of storing both DC and AC electricity have been developed using fiber materials of cellulose molecules obtained from wood and plant fibers (pulp) (see, for example, Non-Patent Documents 16 and 17 or Patent Document 2).

[0009] M. Fukuhara, A. Kawashima, S. Yamaura, and A. Inoue, “Coulomb oscillation of a proton in a Ni-Nb-Zr-H glassy alloy with multiple junctions”, Appl. Phys., 2007, 90, 203111M. Fukuhara and H. Kawarada, “Room-temperature amorphous alloy field-effect transistor exhibiting particle and wave electronic transport”, J. Appl. Phys., 2015, 117, 084302M. Fukuhara, H. Yoshida, K. Koyama, A. Inoue, Y. Miura, “Electronic transport behaviors of Ni-Ngb-Zr-H glassy alloys”, J. Appl. Phys., 2010, 107, 033703Mikio Fukuhara, Hajime Yoshida and Hiroshi Kawarada, “Effect of hydrogen and cluster morphology on the electronic behavior of Ni-Nb-Zr-H glassy alloys with subnanometer-sized icosahedral Zr5Ni5Nb5 clusters”, Euro. Phys. J., D, 2013, 67:40M. Fukuhara and H. Kawarada, “Room-temperature amorphous alloy field-effect transistor exhibiting particle and wave electronic transport”, J. Appl. Phys., 2015, 117, 084302M. Fukuhara, T. Yokotsuka, T. Hashida, F. Ogawa, T. Sakamoto, M. Takeda, S.Arai, “A novel n-type semiconducting biomaterial”, Scientific Reports, 2022, 12, 21899M. 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), p.477-480M. 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.253M. Fukuhara and K. Sugawara, “Anodic oxidization of Ti-Ni-Si amorphous alloy ribbons and their capacitive and resistive properties”, Thin Solid Films, 2015, 595, 1-4M. Fukuhara, T. Kuroda and F. Hasegawa, “Amorphous titanium-oxide supercapacitors”, Sci. Rep., 2016, 6, 35870M. Fukuhara, T. Kuroda, F. Hasegawa and T. Sueyoshi, “Superior electric storage on an amorphous perfluorinated polymer surface,” Sci. Rep., 2016, 6, 22012M. Fukuhara, T. Kuroda, F. Hasegawa, T. Hashida, E.Kwon and K. Konno, “Amorphous aluminum-oxide supercapacitors,” EuroPhys. Lett., 2018, 123, 58004M. Fukuhara, T. Kuroda, F. Hasegawa, Y. Shirai, T. Suwa, T. Hashida, and M. Nishijima, “Amorphous titanium-oxide supercapacitors with high capacitance”, EuroPhys. Lett., 2019, 128, 58001M. Fukuhara, T. Kuroda, F. Hasegawa, T. Hashida, M. Takeda, K. Konnno, and N. Fujima, “AlO6 clusters’ electric storage effect in amorphous alumina supercapacitors”, Sci. Rep., 2021, 11, 1699M. Fukuhara, T. Yokotsuka, T. Hashida, K. Yamaguchi, and N. Fujima, “Amorphous alumina supercapacitors with voltage-charging performance”, EuroPhys. Lett., 2023, 141, 36003M. Fukuhara, T. Kuroda, F. Hasegawa, T. Hashida, and M. Takeda, N. Fujima, M. Morita, and T. Nakatani, “Amorphous cellulose nanofiber supercapacitors”, Sci. Rep., 2021, 11, 6436M. Fukuhara, T. Yokotsuka, T. Hashida, T. Miwa, N. Fujima, M. Morita, and T. Nakatani, and F.Nonomura “Amorphous cellulose nanofiber supercapacitors with voltage-charging performance”, Sci. Rep., 2022, 12, 5619.

[0010] International Publication No. WO2011 / 037003 International Publication No. WO2021 / 166813

[0011] However, the semiconductor using the biomaterial described in Non-Patent Document 6 shows almost no electricity storage effect, and the electricity storage materials made from the biomaterials described in Non-Patent Documents 16 and 17 and Patent Document 2 show no significant semiconducting properties. Thus, no biomaterials have existed to date that have both semiconducting properties and electricity storage properties.

[0012] The present invention has been made in response to these problems, and aims to provide a semiconductor storage material, a storage battery, and a stacked storage battery that are made from biomaterials and have both semiconductor properties and storage properties.

[0013] The inventors have found that, for example, when using crystalline / amorphous CNF with CNF bundles of 3-400 nm produced by mechanical fiberization, semiconducting properties emerge due to the quantum size effect of forming an electric double layer of electrons and protons in the thin film, while at the same time, charge storage properties emerge due to the acetamide and amino groups of the C2 bonds. That is, they have found that this phenomenon occurs due to the formation of proton tunneling (solitonized protons) in the crystalline / amorphous fibers and their aggregates, similar to the previous amorphous Ni-Nb-Zr-H alloys.

[0014] The present inventors have also found that the molecular formula (C8H 13 NO5) n Chitin, represented by (C6H 11 NO4) nThe inventors noticed that in chitosan, a nitrogen-containing polysaccharide polymer, the dipoles formed by hydroxyl groups (OH groups) and acetamide or amino groups (NO groups) are ordered in the same direction. Structurally, this acts similarly to the hydrogen bond chain of the primary bond of water, and they found that it behaves like a chain of protonic solitons, forming an electric double layer with electrons. This is how the inventors arrived at the present invention.

[0015] That is, the semiconductor electricity storage material according to the present invention has fibers mainly composed of chitin or chitosan, is in a sheet shape, and has a density of 2 g / cm 3 The present invention is characterized by the following:

[0016] The semiconductor energy storage material of the present invention has fibers primarily composed of chitin or chitosan, a natural aminopolysaccharide, and is made from biomaterials. The semiconductor energy storage material of the present invention primarily consists of chitin, obtained from the exoskeleton of crustaceans such as crabs and shrimp, or chitosan, obtained by deacetylating chitin through boiling in concentrated alkali. By forming these fibers, it is possible to form dipoles on the inner surface, consisting of numerous hydroxyl groups bonded to acetamide groups in the case of chitin or amino groups in the case of chitosan. Furthermore, as with cellulose obtained by polymerizing β-glucose, the molecules readily form a sheet-like structure through hydrogen bonding, allowing for the instantaneous formation of an electric double layer, which is the basis for proton transfer. This allows the semiconductor energy storage material of the present invention to have a high-dielectric domain structure due to the formation of an electric double layer, thereby exhibiting both semiconducting and energy storage properties.

[0017] The semiconductor energy storage material of the present invention can be represented by an equivalent circuit in which two electric circuits each consisting of an electric double layer are connected in parallel. This allows the semiconductor energy storage material of the present invention to become a transistor that exhibits various functions. In the semiconductor energy storage material of the present invention, the positively charged dipole formed by the (NO) group of the acetamide group or amino group contributes to the physical adsorption of negatively charged electrons.

[0018] The semiconductor energy storage material according to the present invention has an equivalent circuit in which the electrical resistivity of the two electric double layers is 10 -1 ~1012 Preferably, it is 10 Ωm. 3 Ωm or more 10 7 It is more preferable that the capacitance of each electric double layer is 10 Ωm or less. -8 ~10 -5 Preferably it is F.

[0019] The semiconductor electricity storage material according to the present invention is preferably in the form of a sheet having a thickness of 100 μm or less, and more preferably in the form of a thin film having a thickness of 20 μm or less, which is particularly expected to have a weight-saving effect.

[0020] In the semiconductor energy storage material of the present invention, "fibers whose main component is chitin or chitosan" refers to fibers containing more than 50% by mass of chitin or chitosan, which are derived from crabs, shrimp, or insects such as silkworms, cicadas, and beetles, or antibacterial substances such as filamentous fungi, and more specifically, are derived from the main components of the cuticles that cover the body surfaces of many invertebrates, such as the exoskeletons (i.e., skins) of arthropods and crustaceans, and the surface of the shells of mollusks, or the cell membranes of fungi such as molds and mushrooms.

[0021] In the semiconductor energy storage material according to the present invention, the fiber is preferably a crystallized amorphous fiber. In this case, the fiber may have nanocrystals. Alternatively, the fiber may be an amorphous fiber having atomic vacancies. The material of the crystallized amorphous fiber may be any material capable of forming an electric double layer on its inner surface, such as chitin fiber or chitosan fiber. As the chitin fiber and chitosan fiber, chitin nanofiber and chitosan nanofiber are preferably used, respectively. Chitin nanofiber and chitosan nanofiber can enhance the electron adsorption ability due to the negative sixth power quantum size effect, thereby increasing the work function and further enlarging the dielectric domain.

[0022] Chitin fiber and chitosan fiber may be of any type, and mucopolysaccharide polymers derived from microorganisms such as arthropods, mollusks (e.g., squid), insects (e.g., silkworms, beetles, cicadas), and fungi (e.g., molds and mushrooms) can be used. Fibers derived from animals are preferred, and chitosan fiber derived from crab, shrimp, or mantis shrimp is particularly preferred.

[0023] Chitin and chitosan fibers may have any average fiber diameter. The average fiber length and average fiber diameter of chitin and chitosan fibers can be adjusted by oxidation treatment and defibration treatment. Here, nanofibers are fine fibers with a fiber diameter of about 3 to 400 nm after general refinement, depending on the degree of defibration. The average fiber diameter and average fiber length of nanofibers are obtained by averaging the fiber diameters and fiber lengths obtained from the results of observing each fiber using an atomic force microscope (AFM) or a transmission electron microscope (TEM).

[0024] Chitin nanofibers and chitosan nanofibers preferably have an average aspect ratio of 50 or less, and are particularly preferably aggregated in a granular form. Granular refers to nanofibers that have been finely pulverized by defibration. The average aspect ratio can be calculated using the following formula: Average aspect ratio = average fiber length / average fiber diameter

[0025] [Defibrillation of chitin and chitosan fibers] Any method may be used for the defibrillation of chitin and chitosan fibers, but a method of applying a strong shear force to a dispersion of chitin or chitosan fibers using a high-speed rotary, colloid mill, high-pressure, roll mill, ultrasonic, or other device is preferred. For efficient defibrillation, it is preferable to use a wet high-pressure or ultra-high-pressure homogenizer as the defibrillation device, which can apply a pressure of 50 MPa or more and a strong shear force to a dispersion of chitin or chitosan fibers. The pressure during defibrillation is preferably 100 MPa or more, and more preferably 140 MPa or more. The number of treatments (passes) with the defibrillation device may be one, but is preferably two or more.

[0026] In the dispersion treatment to form the dispersion, it is preferable to disperse chitin fibers or chitosan fibers in a solvent. The solvent may be any solvent that can disperse chitin fibers or chitosan fibers, such as water, an organic solvent (e.g., ethanol, acetic acid, lactic acid, succinic acid), or a mixture thereof. Because cellulose fibers are hydrophilic, water is particularly preferable as the solvent.

[0027] Furthermore, prior to the defibration and dispersion treatment using a high-pressure homogenizer, the chitin or chitosan fibers may be subjected to a pretreatment, if necessary, using, for example, a mixing, stirring, emulsifying, and dispersing device such as a high-speed shear mixer.

[0028] In the semiconductor energy storage material according to the present invention, the chitin and chitosan fibers may be in the form of an aqueous dispersion obtained after defibration, or may be subjected to post-treatment as necessary, such as drying (freeze drying, spray drying, tray drying, drum drying, belt drying, thin spreading on a glass plate or the like and drying, fluidized bed drying, microwave drying, heated fan-type vacuum drying, etc.), re-dispersion in water (any dispersing device may be used), pulverization (pulverization using equipment such as a cutter mill, hammer mill, pin mill, jet mill, or bead mill), or high-speed rotary filtration using a Fermix disperser.

[0029] In the semiconductor electricity storage material according to the present invention, the fibers are preferably made of chitin nanofibers having a width of 3 to 400 nm, or bundles or granular aggregates of the chitosan nanofibers, which can increase the efficiency of forming an electric double layer.

[0030] In the semiconductor electricity storage material according to the present invention, the specific surface area of ​​the fiber is 750 to 900 m 2 / g, and in particular, 800 to 900 m 2 / g is preferred.

[0031] The semiconductor energy storage material according to the present invention is preferably an n-type bulk semiconductor, and in this case, can be represented by an equivalent circuit consisting of two parallel circuits having two bands: a small-current low-resistance band and a large-current high-resistance band.

[0032] The semiconductor energy storage material according to the present invention is preferably made of a bulk semiconductor having N-type negative resistance. In particular, it is preferable that the material exhibits N-type negative resistance under a high voltage load of 1 kV / cm or more. In this case, the material can be used, for example, as a DC / AC conversion element or a metal-insulator switching element, and also has a rectifying effect.

[0033] The electricity storage unit according to the present invention is characterized by having the semiconductor electricity storage material according to the present invention and a pair of metal electrodes provided on both sides of the semiconductor electricity storage material so as to sandwich the semiconductor electricity storage material.

[0034] The power storage device according to the present invention is equivalent to a lumped-element capacitor having two macroscopic capacitors between each metal electrode. Furthermore, in the power storage device according to the present invention, each metal electrode is made of, for example, Al, Cu, gold, polythiophene, or the like, and can be manufactured by a sputtering method, a casting method, or a doctor blade method using a microelectromechanical system (M(N)EMS). Furthermore, the power storage device according to the present invention is preferably operable at temperatures between -269°C and 300°C.

[0035] The electricity storage unit according to the present invention may be a parallel assembly in which a plurality of the semiconductor electricity storage materials are arranged between a pair of electrodes made of a conductor. 2 The electrodes are made of, for example, a metal or a conductive polymer.

[0036] The stacked electricity storage unit according to the present invention is characterized by comprising a stack of a plurality of electricity storage units according to the present invention stacked one on top of the other.

[0037] The stacked power storage unit according to the present invention can be stacked in parallel by, for example, various M(N)EMS methods. As a semiconductor, the stacked power storage unit according to the present invention can be represented as a plurality of parallel equivalent circuits coupled in the form of lumped electrical parameters, and as a power storage unit, as a plurality of parallel equivalent circuits coupled in the form of distributed electrical parameters.

[0038] The semiconductor electricity storage material, electricity storage unit, and laminated electricity storage unit according to the present invention can be used as a semiconductor, for example, as an AC transmitter or control device for a microelectronic circuit, an overcurrent protection switch, etc. They can also be used in electronic and electrical substrates such as various amplifiers, microwave transmitters, pump sources for parametric amplifiers, police radar, door opening / closing systems, trespassing detection systems, shunt regulators, and protection circuits.

[0039] The semiconductor energy storage material, energy storage unit, and laminated energy storage unit according to the present invention can be used as an energy storage unit, for example, as an AC capacitor in a microelectronic circuit or as an energy storage unit on the back surface of a solar cell panel. They can also be used in various backup power supply modules, coupling elements, noise filters, high-sensitivity acceleration sensors, high-output transformer cutoff prevention devices, emergency power supply devices for automobiles or ships, and other electronic and electrical circuit boards. They are also expected to be used in the future as DC energy storage materials for sunlight in outer space. Examples of energy storage units include antistatic sheets, lightning protection paper, electronic device shielding paper, films, positively charged dust absorption paper, and paint films.

[0040] According to the present invention, it is possible to provide a semiconductor electricity storage material, electricity storage unit, and stacked electricity storage unit that are made of a biomaterial and have both semiconductor properties and electricity storage properties.

[0041] 1 is a perspective view showing the molecular structures of (a) chitin and (b) chitosan constituting the fibers of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 2 is an electrical circuit diagram showing an equivalent circuit of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 3 is a graph showing the results of frequency analysis of current in the N-type negative resistance region of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 4 is an atomic force microscope (AFM) image of the surface of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 5 is a graph showing a complex plane representation of impedance and a Nyquist diagram of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 6 is a graph showing the IV characteristics of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 7 is a graph showing a discharge curve of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 8 is a graph showing the RV characteristics of the semiconductor electricity storage material according to an embodiment of the present invention; FIG. 9 is a side view, (d) a perspective view, (e) a side view showing a method for manufacturing a stacked electricity storage unit according to an embodiment of the present invention using a MEMS method; and FIG. 10 is a plan view, (f) a perspective view, and (g) a plan view of an equivalent circuit of the manufactured stacked electricity storage unit.

[0042] Hereinafter, embodiments of the present invention will be described with reference to the drawings and examples, etc. The semiconductor electricity storage material of the embodiment of the present invention is made of crystallized amorphous fibers mainly composed of chitin as shown in Figure 1(a) or chitosan as shown in Figure 1(b), and is in the form of a sheet having numerous irregularities on its surface.

[0043] The semiconductor energy storage material according to the embodiment of the present invention has a high dielectric domain structure in which an electric double layer is formed, and can exhibit both semiconducting properties and energy storage properties. As a result, as shown in Figure 2, the semiconductor energy storage material according to the embodiment of the present invention is equivalent to an electric lumped constant circuit in which two electric circuits each consisting of an electric double layer are connected in parallel. As a result, the semiconductor energy storage material according to the embodiment of the present invention can become a transistor that exhibits various functions.

[0044] Semiconductor electricity storage materials according to embodiments of the present invention were manufactured and their electrical properties were examined below. Note that the following examples are provided merely to explain the present invention and to provide reference for specific embodiments thereof, and are not intended to limit or restrict the scope of the invention disclosed in this application.

[0045] Sample 1, an embodiment of the semiconductor energy storage material of the present invention, was manufactured as follows. Red snow crab shells, which have a low calcium content, were used as raw materials. The shells were immersed in 2 mol / L (2N) hydrochloric acid for 5 hours, then washed with water, dried, and pulverized. They were then decalcified by stirring in hydrochloric acid for 48 hours. The shells were then placed in 1 mol / L (1N) sodium hydroxide and heated at 100°C for 12 hours, a process repeated four times to remove proteins. The resulting chitin was then dried to obtain crude chitin. The crude chitin was then immersed in 0.5% potassium permanganate solution for 1 hour, washed with water, and then placed in 1% oxalic acid solution and stirred at 60°C for 40 minutes to obtain pure white α-chitin. The chitin was then defibrated using a roll mill.

[0046] Using the defibrated α-chitin, a 2% aqueous chitin slurry was prepared using the doctor blade method, and the water was evaporated and dried on a hot plate at 100°C to produce an α-chitin sheet (Sample 1).

[0047] Observation of the surface of the α-chitin sheet of Sample 1 using an atomic force microscope (AFM) confirmed that it was composed of bundles of fibrous chitin nanofibers with widths of 3 to 400 nm. It was also confirmed that the chitin nanofibers were amorphous fibers.

[0048] A pair of metal electrodes was placed on both sides of the α-chitin sheet of sample 1, sandwiching sample 1, and various measurements were performed. First, an AC signal was applied between the electrodes using the AC impedance method to measure the absolute value of the impedance of sample 1 and the phase difference between the voltage and current. Carbon with a work function of 5.0 and aluminum with a work function of 4.2 were used for each electrode, forming a Schottky junction circuit. When the measurement results were plotted on a complex plane, it was confirmed that they were plotted along a line of two arcs, one large and one small.

[0049] Therefore, in the equivalent circuit shown in FIG. １ , R ２ and the electrical resistivity of the capacitor C １ , C ２The electrical capacitance of the sample was changed, and the Nyquist diagram that best fit the measurement results was determined by the least squares method. １ = 35 kΩm, R ２ = 21 kΩm, C １ = 3 x 10 -8 F, C ２ = 7 x 10 -7 From these results, it was confirmed that Sample 1 is equivalent to an electrical lumped constant circuit having two macroscopic capacitors (electric double layers) as shown in Figure 2, and forms a semiconductor having two bands: a small-current low-resistance band and a large-current high-resistance band.

[0050] Next, a voltage was applied between the electrodes of Sample 1, and the I-V characteristics at room temperature were measured. As a result, it was confirmed that Sample 1 exhibited semiconductor characteristics, showing N-type negative resistance, between -70 V and -60 V. It was also confirmed that Sample 1 exhibited rectification, where no current flows in the negative charge region, but the current increases sharply in the positive charge region.

[0051] The current between each electrode was measured between -70 V and -60 V, and its frequency was analyzed. The results are shown in Figure 3. As shown in Figure 3, a vibration frequency peak was confirmed at 1.5 kHz. From this result, it is believed that Sample 1 is performing DC / AC conversion. This result is similar to the Gunn effect observed in GaAs (gallium arsenide) semiconductors.

[0052] Next, Sample 1 was charged at 450 V for 3 seconds, and then discharged to obtain a discharge curve. The amount of stored electricity was calculated from the area enclosed by the discharge curve, the voltage axis, and the time axis, and was found to be 502.5 mJ / m 2 It was.

[0053] The density of sample 1 was measured and found to be 1.4 g / cm 3 and 2 g / cm 3 It was also confirmed that Sample 1 could be operated up to 500 V in a low-medium temperature furnace at temperatures ranging from -269 °C to 200 °C. The specific surface area of ​​Sample 1 was measured by the BET adsorption method and found to be 800 m 2 / g.

[0054] Sample 2, a semiconductor electricity storage material according to an embodiment of the present invention, was produced as follows. The α-chitin from Sample 1 before defibration was defibrated using a homogenizer, and then placed in a 48% sodium hydroxide solution and reacted at 120°C for 30 minutes to obtain chitosan. A 2% aqueous chitosan slurry was produced from the chitosan, and the slurry was dropped onto a Si substrate in a spin coater. The Si substrate was rotated at 500 rpm to form a thin film, which was then dried on a hot plate at 100°C to evaporate the water, producing a chitosan sheet.

[0055] The surface of the chitosan sheet of Sample 2 was observed with an atomic force microscope (AFM). An AFM image of Sample 2 is shown in Figure 4. As shown in Figure 4, it was confirmed that the chitosan sheet of Sample 2 was formed from a series of bundles or granular aggregates of fibrous chitosan nanofibers of 200 to 400 nm. It was also confirmed that the chitosan nanofibers were amorphous fibers.

[0056] A pair of metal electrodes was provided on both sides of the chitosan sheet of Sample 2 so as to sandwich Sample 2, and various measurements were performed. First, the absolute value of the impedance of Sample 2 and the phase difference between the voltage and current were measured using the AC impedance method in the same manner as in Example 1. The measurement results were plotted on a complex plane and are shown in Figure 5. As shown in Figure 5, it was confirmed that the measurement results were plotted along a shape consisting of two arcs, one large and one small, lined up next to each other.

[0057] Therefore, similarly to the first embodiment, in the equivalent circuit shown in FIG. １ , R ２ and the electrical resistivity of the capacitor C １ , C ２ The electrical capacitance of R was changed, and the Nyquist diagram that best fits the measurement results shown in FIG. 5 was obtained by the least squares method, and is shown by the solid line in FIG. 5. The electrical resistivity and electrical capacitance at this time are １ = 17 kΩm, R ２ = 5 kΩm, C １ = 3 x 10 -7 F, C ２ = 5 x 10 -6 As shown in Figure 5, the measurement results and the Nyquist diagram are in close agreement, and it was therefore confirmed that, like Sample 1, Sample 2 is equivalent to an electric lumped parameter circuit having two macroscopic capacitors (electric double layers) as shown in Figure 2, and forms a semiconductor having two bands: a small-current low-resistance band and a large-current high-resistance band.

[0058] Next, a voltage was applied between the electrodes of Sample 2, and the I-V characteristics at room temperature were measured. The results are shown in Figure 6. As shown in Figure 6, Sample 2 was confirmed to exhibit semiconductor characteristics showing N-type negative resistance between -180 V and -170 V and between -70 V and -60 V (the ranges circled A and B in the figure). It was also confirmed that Sample 2 exhibits rectification, where no current flows in the negative charge region, but the current increases sharply in the positive charge region (the range circled C in the figure).

[0059] Next, the discharge curve when Sample 2 was discharged after being charged at 450 V for 3 seconds is shown in Figure 7. The amount of stored electricity was calculated from the area enclosed by the discharge curve, voltage axis, and time axis (Discharge Time) shown in Figure 7, and was found to be 1004.4 mJ / m 2 It is believed that the amount of stored electricity will improve with a high voltage load of 400 V or more.

[0060] Furthermore, the density of sample 2 was measured and found to be 1.0 g / cm 3 and 2 g / cm 3 It was also confirmed that Sample 2 could be operated up to 500 V in a low-medium temperature furnace at temperatures ranging from -269 °C to 200 °C. The specific surface area of ​​Sample 2 was measured by the BET adsorption method and found to be 800 m 2 / g.

[0061] Sample 3, a semiconductor energy storage material embodying the present invention, was manufactured as follows. Squid bones were used as raw materials. The raw materials were immersed in 2 mol / L (2N) hydrochloric acid for 5 hours, then washed with water, dried, and pulverized. They were then decalcified with hydrochloric acid for 48 hours while stirring. The raw materials were then placed in 1 mol / L (1N) sodium hydroxide and heated at 100°C for 12 hours, a process repeated four times to remove proteins. The resulting material was then dried to obtain crude chitin. The crude chitin was then immersed in 0.5% potassium permanganate solution for 1 hour, washed with water, and then placed in 1% oxalic acid solution and stirred at 60°C for 40 minutes to obtain β-chitin. This β-chitin has balanced sugar chains and loose hydrogen bonds, making it easy to handle. However, the yield of the squid bones used as raw materials was lower than that of the crab used in Sample 1.

[0062] The β-chitin was defibrated using the cutter mill method, and then a 2% chitin aqueous solution slurry was prepared using the doctor blade method. The water was evaporated and the mixture was dried on a hot plate at 50°C to produce the β-chitin sheet of sample 1.

[0063] Observation of the surface of the β-chitin sheet of Sample 3 with an atomic force microscope (AFM) confirmed that it was composed of bundles of fibrous chitin nanofibers with widths of 3 to 400 nm. It was also confirmed that the chitin nanofibers consisted of amorphous fibers containing 5% nanocrystals.

[0064] A pair of metal electrodes was placed on both sides of the β-chitin sheet of sample 3 so as to sandwich sample 3, and various measurements were carried out. First, the absolute value of the impedance of sample 3 and the phase difference between the voltage and current were measured by the AC impedance method in the same manner as in Example 1, and a Nyquist diagram was obtained. The electrical resistivity and capacitance at this time were calculated using the R １ = 14 kΩm, R ２ = 7 kΩm, C １ = 5 x 10 -8 F, C ２ = 4 x 10 -7 From these results, it was confirmed that, like Sample 1, Sample 3 is equivalent to an electric lumped constant circuit having two macroscopic capacitors (electric double layers) as shown in Figure 2, and forms a semiconductor having two bands: a small-current low-resistance band and a large-current high-resistance band.

[0065] Next, sample 3 was charged at 450 V for 3 seconds, and then discharged to obtain a discharge curve. The amount of stored electricity was calculated from the area enclosed by the discharge curve, the voltage axis, and the time axis, and was found to be 240.1 mJ / m 2 It was.

[0066] Next, a voltage was applied between the electrodes of Sample 3, and the R-V characteristics at room temperature were measured. The results are shown in Figure 8. As shown in Figure 8, it was confirmed that the resistance value of Sample 3 rose sharply by about three to four orders of magnitude from 0 V to approximately 1.5 V as the voltage increased, and then dropped by about three orders of magnitude. This result is thought to be due to the metal-insulator switching effect. This is thought to be due not to the effect of a pn junction semiconductor, but to the effect of a semiconductor having two bands, a small-current low-resistance band and a large-current high-resistance band, which are characteristic of n-type bulk semiconductors.

[0067] Furthermore, the density of sample 3 was measured and found to be 1.5 g / cm 3 and 2 g / cm 3 It was also confirmed that Sample 3 could be operated up to 500 V in a low-medium temperature furnace at temperatures ranging from -269 °C to 200 °C. The specific surface area of ​​Sample 3 was measured by the BET adsorption method and found to be 800 m 2 / g.

[0068] The sample type, defibration method during manufacturing, structure (crystalline / amorphous), density, electrical resistivity, electrical capacity, and storage capacity of the semiconductor energy storage materials for Samples 1 to 3 are summarized in Table 1.

[0069]

[0070] As shown in Table 1, each of the semiconductor electricity storage materials of Samples 1 to 3 has an AC electric resistance R １ is 14 to 35 kΩm, R ２ 5 to 21 kΩm, and the capacitance C１ is 10 -8 F to 10 -6 F, C ２ is 10 -7 F to 10 -5 It was confirmed that this is the reason why a bulk n-type semiconductor phenomenon appears, not a pn junction. 3 It was also confirmed that Samples 1 to 3 have low densities of 800 m or less. It was also confirmed that Samples 1 to 3 have charge storage properties and can operate up to 500 V in the range of -269 °C to 200 °C. Furthermore, it was confirmed that Samples 1 to 3 have specific surface areas of 800 m or less. 2 It was also confirmed that the biomass semiconductor energy storage materials of Samples 1 to 3 are optimal for use in the low-voltage field.

[0071] For sample 2, 3 mA / m 2 When exposed to a powerful electron beam of 100 keV, it was confirmed that the material had electrical resistance up to 200 keV, which is more than twice the electrical resistance of carbon nanotubes, which have an electrical resistance of 80 keV.

[0072] FIG. 9 shows a stacked power storage element according to an embodiment of the present invention. As shown in FIG. 9, the stacked power storage element according to the embodiment of the present invention is fabricated by a MEMS method using a sheet-shaped semiconductor power storage material, Sample 2, as follows. First, as shown in FIG. 9(a), a Cu layer (500 nm thick) is formed by sputtering on the surface of a glass substrate (40 × 40 × 0.5 mm). Next, as shown in FIG. 9(b), sheet-shaped Sample 2 is placed on the Cu layer, and then, as shown in FIG. 9(c), an Al layer (500 nm thick) is formed by sputtering on the Cu layer. This results in the fabrication of a sheet-shaped semiconductor power storage element, as shown in FIG. 9(d), having a carbon layer and an Al layer as metal electrodes on both sides. This structure corresponds to Samples 1 to 3, which were used in the various measurements in Examples 1 to 3 and have metal electrodes on both sides.

[0073] Next, the glass substrate is removed to form a single base body, and a plurality of such base bodies are stacked to produce the stacked electricity storage unit of the embodiment of the present invention shown in Fig. 9(e). The produced stacked electricity storage unit has a plurality of semiconductor electricity storage materials joined in parallel, with the Al layer of the top base body and the carbon layer of the bottom base body serving as terminals, as shown in Figs. 9(f) and (g).

[0074] Taking advantage of its light weight, the semiconductor energy storage material of the embodiment of the present invention can be used in a wide range of applications, from low-voltage applications such as mobile phones, drones, and wall-mounted televisions to heavy-voltage applications such as automobiles, ships, and airplanes. It can also be used, for example, in power supply modules for lightning arresters, welding, and over-discharge prevention, as well as in noise filters, sensors for door opening / closing systems, trespassing detection systems, and pedestrian safety systems, and in electronic and electrical circuit boards for microelectronics control devices, remote vibration detectors, and transmitters. Examples of energy storage materials include antistatic sheets, lightning protection paper, electronic device shielding paper, films, positively charged dust adsorption paper, and paint films.

Claims

1. A sheet-shaped fiber made mainly of chitin or chitosan with a density of 2 g / cm 3 A semiconductor electricity storage material characterized by:

2. The semiconductor storage material according to claim 1, wherein said fiber is a crystallized amorphous fiber.

3. The semiconductor storage material according to claim 1, characterized in that the fibers are composed of chitin nanofibers having a width of 3 to 400 nm, or bundles or granular aggregates of the chitosan nanofibers.

4. The specific surface area of ​​the fiber is 750 to 900 m 2 / g of the semiconductor storage material according to claim 1.

5. The semiconductor storage material according to claim 1, which is an n-type bulk semiconductor.

6. The semiconductor electricity storage material according to claim 1, characterized in that it has N-type negative resistance.

7. A storage battery comprising the semiconductor storage material according to any one of claims 1 to 6, and a pair of metal electrodes provided on both sides of the semiconductor storage material so as to sandwich the semiconductor storage material.

8. A stacked electricity storage unit comprising a plurality of electricity storage units according to claim 7 stacked together.

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