JP6628241B2 - Energy storage materials and energy storage devices - Google Patents

Description

  The present invention relates to a power storage material and a power storage device.

  Capacitors are electronic components that store or discharge electric charge (electric energy) due to their capacitance. In mobile electronic devices such as personal computers and mobile phones, the stability of power supplies, backup circuits, coupling elements, and noise It plays the role of a filter, etc., and is an indispensable part for electronic equipment. In recent years, high-performance IT products such as mobile phones and ultra-small storage devices and batteries for electric vehicles have rapidly evolved, and the demand for capacitors that are even smaller, have large capacities, and have high functions such as memories has increased. In particular, there is a need for a product that is suitable for a smart grid (next generation transmission network) society that matches green innovation (low-carbonization) for preventing global warming.

  Capacitors are roughly classified into high-voltage power circuits (heavy electricity) and electronic / electrical equipment circuits (light electricity), depending on the application. Among them, ceramic capacitors are mainly used as capacitors for electronic / electric equipment circuits in the field of light electricity, and secondary batteries are also heavily used for electric storage of mobile phones and the like.

Power storage units using capacitors are widely used from 1 pF to several tens of mF as main components of electronic and electrical equipment. The storage capacity C (F) is
C = Q / V = ε × (A / d)
(Here, Q: electric charge, V: voltage, ε: dielectric constant, A: electrode area, d: distance between electrodes) Therefore, the larger the electrode area and the smaller the distance between electrodes, the higher the charge capacity. . However, from the viewpoint of reducing the size and weight of electronic and electric devices and the required storage capacity, the electrode area A is increased, the distance d between the electrodes is reduced to achieve the maximum capacity, and the electrode area A is reduced. It is difficult to increase the distance d between the electrodes to minimize the capacitance.

Regarding the power storage device, the present inventors have found that the charge of direct current is low in a Si— (Al, Ti, V) alloy or a TiO ₂ coated Ti—Ni—Si amorphous alloy in which Al, Ti, and V are surface-extracted and removed. It has been found that the data can be stored regardless of the AC (for example, see Non-Patent Documents 1 to 5, and Patent Documents 1 and 2).

In addition, research has been reported on nanosheet thin film capacitor elements of perovskite Sr ₂ Nb ₃ O ₁₀ and Ca ₂ Nb ₃ O ₁₀ having a film thickness of 10 nm or less and having a dielectric constant of 210 to 240 (for example, Non-Patent Document 6). ), The distance between the electrodes is large, and because of the ceramics, bonding with the electrode material is not easy, and the contact resistance is high. A high specific capacity of 1,160 F / cm ³ has been reported for a nanoporous Au-based amorphous alloy separator coated with MnO ₂ in a chemical electrolyte (for example, see Non-Patent Document 7). This is an application of an electrochemical cell.

  Further, a physical secondary battery having a voltage of 1.5 V, a power of 500 Wh / L, an output density of 8 kW / L, a cycle life of 100,000 times, and an operating temperature range of −25 ° C. to + 85 ° C. has been developed (for example, non-patented). Reference 8), which uses a Schottky junction in which an electron trap level is formed in a band gap of a semiconductor and charge / discharge is performed by filling or emptying the level with an electric potential. .5V.

In addition, the cyclic polymerization main chain in which the 5-membered ring structure of perfluoro (butenyl vinyl ether) and the-(CF ₂ -CF ₂ )-unit are alternately present has a polar group such as γ-aminopropyltriethoxysilane. By adding aminosilane as a functional group as an additive, an aminosilane cluster on the order of nanometers is formed, and an electret having a high surface potential is obtained by utilizing its structure (for example, Non-Patent Document 9 or Patent Document 3).

M. Fukuhara, T. Araki, K. Nagayama and H. Sakuraba, “Electric storage in de-alloyed Si-Al alloy ribbons”, EuroPhys. Lett., 2012, 99, 47001 M. Fukuhara, “Electric Charging / Discharging Characteristics of Capacitor, Using De-alloyed Si-20Al Alloy Ribbons”, Elect.Electr. Eng., 2013, 3 (2), p.72-76 M. Fukuhara and H. Yoshida, “AC charging / discharging of de-alloyed Si-Al-V alloy ribbons”, J. Alloys and Comp., 2014, 586, S130-S133 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), p.477-480 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 M. Osada, K. Akatsuka, Y. Ebina, H. Funakubo, K. Ono, K. Takada and T. Sasaki, “Robust high-k response in molecularly thin perovskite nanosheets”, ACS NANO, 2010, 4, p. 5225-5232 X. Y. Lang, A. Hirata, T. Fujita and M. W. Chen, “Nanoporous metal / oxide hybrid electrodes for electrochemical supercapacitors”, Nature Nanotechnology, 2011, 6, p.232-236 Japan Micronics Co., Ltd., rechargeable battery battenice, <http://www.mjc.co.jp/product/index3.html> K. Kashiwagi, K. Okano, T. Miyajima, Y. Sera, N. Tanabe, Y. Morizawa and Y. Suzuki, “Nano-cluster-enhanced high-performance perfluoro-polymer electrets for energy harvesting”, J. Micromech. Microeng., 2011, 21, 125016

JP 2012-253321 A JP 2015-57808 A International Publication WO2009 / 128503

  Non-Patent Documents 1 to 8 and Patent Documents 1 and 2 disclose that electric storage materials such as capacitors in the field of weak electricity use chemical ion transfer, and therefore have a slow response and have an instantaneous or relatively short time. There was a problem that electricity could not be stored. In addition, the withstand voltage is about 4 V, there is a problem that large-capacity power storage cannot be performed, and long-term discharge is impossible.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a power storage material and a power storage device which can store power instantaneously or for a relatively short time and can discharge for a long time by large-capacity power storage. Aim.

The present inventors performed a structural analysis of the amorphous resin described in Non-Patent Document 9 and Patent Document 3, and found that a fluorine atom was arranged in a spiral shape around a 5-membered ring carbon atom, and the CF ₂ unit It has been found that aminosilanes are arranged as side chains around the main chain. In addition, between the CF ₂ unit and the silane main body, carbonyl groups and amino groups formed by (chemical) phase separation by fluorine / non-fluorine form an amorphous structure as clusters on the order of nanometers. It also found that it functions as a positive ion site.

  Further, the work function as a measure of the magnitude of the electron adsorption ability on the surface of the fluoropolymer was 9 to 14 eV, which was the largest value among the existing substances. It is well known that elemental fluorine has the largest electron adsorption capacity in the charging train.

  Further, the present inventors also discovered that the surface of the fluorine / non-fluorine phase separator had a plurality of irregularities having a diameter of 0.1 to 30 nm. Here, when irregularities having a diameter of 0.1 to 30 nm and a height difference of 0.1 to 30 nm are formed on the surface of a fluorine or chlorine resin having a high electric resistance of 1 GΩcm or more, excessive electron adsorption is caused on the projections. The occurrence of the phenomenon has already been discovered by the present inventors (see Non-Patent Document 4). This is a phenomenon that when the metal particles of Au, Ag, Cu, and Pt are 100 nm or less, desirably 30 nm or less, the electrons of internal atoms rapidly increase with respect to the outermost layer electrons, causing lattice shrinkage. This is a quantum phenomenon explained by the theory of electron shielding that occurs on the surface of a solid body. Also, the smaller the pore size is in nano size, the more the electron-adsorbing ability thereof becomes parabolically.

  Based on the above findings, the present inventors have found that even if the amount of charge increases due to the excessive electron adsorption phenomenon on the surface of the fluorine / non-fluorine phase separator, the dipole fine space between the fluorine atoms and the clusters will Since positive electric charges are stored in an electric double layer, it is considered that electrical neutrality is maintained by the positive electric charges and dielectric breakdown is avoided, and the present invention has been accomplished.

In other words, electricity storage material according to the present invention, electron affinity seen contains the above elements 290kJ / mol, (1) at both ends of the amorphous fluorine resin represented by formula, aminosilyl group or a carbonyl group is connected as a side chain It is made of an amorphous polymer, has a plurality of irregularities on the surface with a diameter of 0.1 to 30 nm, a height difference of 0.1 to 30 nm, an electric resistivity of 1 GΩcm or more, and a water absorption of less than 0.01%. It is characterized by.

  The electricity storage material according to the present invention performs electricity storage and discharge by utilizing an electron adsorption phenomenon generated in a plurality of projections of unevenness on a surface having a diameter of 0.1 to 30 nm and a height difference of 0.1 to 30 nm. Can be. In particular, power can be stored instantaneously or for a relatively short time, and large-capacity power can be discharged for a long time.

The power storage material according to the present invention is preferably capable of storing a charge of 1 mF / cm ^{3 to} 10,000 F / cm ^{3 on} the surface of the amorphous polymer. In addition, it is preferable that electric power can be stored instantaneously or in a short time for 1 ms to 1 minute, and discharge can be performed for a long time of one day or more. Further, it is preferable to have a rapid response charge / discharge property of 30 to 100 kHz. The amorphous polymer preferably has a specific surface area of 1,000 m ² / g or more. Further, the amorphous polymer may be made of a polyvinylidene chloride-based amorphous resin. Further, it is preferable that the amorphous polymer is optically transparent and has a light-responsive electric storage property.

  The electricity storage material according to the present invention preferably has a thin film shape and is formed by a casting method, a melt molding method, a sintering method, a spin coating method or a sputtering method. Further, it is preferable that the specific surface area can be increased by 10 to 100 times by dry etching in the MEMS processing.

An electric storage device according to the present invention includes the electric storage material according to the present invention.
The power storage device according to the present invention can store power instantaneously or for a relatively short time by using a power storage material, and can discharge for a long time by large-capacity power storage.

  In the power storage device according to the present invention, it is preferable that the power storage material is in the form of a thin film, and is formed of a power storage body having a pair of metal electrodes provided on both surfaces of the power storage material so as to sandwich the power storage material. In this case, it is equivalent to having a plurality of nano-order minute capacitors perpendicular to each metal electrode corresponding to the number of irregularities. That is, each concavity and convexity has a high electric resistance, and can be represented by a simple parallel equivalent circuit of C and R. Further, it can be manufactured by a micro electro mechanical system (MEMS) method. In addition, it is preferable that it has a withstand voltage of 100 MV / m or more. Further, it is preferable that the device can be operated at -269 ° C to 300 ° C.

  The power storage device according to the present invention may be formed of a laminate in which a plurality of the power storage bodies are stacked. In this case, for example, the layers can be stacked in parallel by a MEMS method such as spin coating or dip coating, and each simple parallel equivalent circuit is a solid-state electronic direct storage device in which electric lumped constants are coupled. The power storage device according to the present invention can be used as an AC capacitor of a microelectronic circuit or a power storage body on the back surface of a solar cell panel.

  According to the present invention, it is possible to provide a power storage material and a power storage device capable of storing power instantaneously or for a relatively short time and discharging for a long time by large-capacity power storage.

2A is a surface shape atomic force microscope (AFM) image, and FIG. 2B is a scanning non-contact Kelvin probe (SKPM) image of the electricity storage material according to the embodiment of the present invention. 2A and 2B are graphs showing DC charge / discharge characteristics of the power storage material shown in FIG. 1, in which (a) a discharge amount at the time of spontaneous discharge, and (b) a discharge amount at the time of constant current discharge. 2A is a Nyquist diagram of AC impedance, FIG. 2B is an impedance diagram of a Bode diagram, FIG. 3C is a phase diagram of a Bode diagram, and FIG. FIG. 1 shows the DC charging / discharging characteristics when the surface area of the electricity storage material shown in FIG. 1 is changed. (A) Discharge amount at spontaneous discharge, (b) Discharge amount at constant current discharge, (c) Discharge amount with respect to area. It is a graph. It is a side view showing the manufacturing method of the layered product by the MEMS method using the electric storage material of an embodiment of the invention.

  Hereinafter, a power storage material and a power storage device according to an embodiment of the present invention will be described based on examples.

As the electricity storage material, a polymer in which an aminosilyl group was connected as a side chain to both ends of an amorphous fluororesin represented by the formula (1) was used. Formula (2) shows the chemical formula of this electricity storage material. Here, n in the equation (2) is a natural number. "CYTOP (registered trademark)" manufactured by Asahi Glass Co., Ltd. was used as the amorphous fluororesin. The volume resistivity of CYTOP is greater than 10 ¹⁷ Ωcm, and the water absorption is less than 0.01%. The capacitor / storage volume is 1.2 × 10 ⁻¹¹ m ³ , and the storage capacity is 83 F / m ³ .

  FIG. 1 shows a surface shape atomic force microscope (AFM) image and a scanning non-contact Kelvin probe (SKPM) image of the used electric storage material. As shown in FIG. 1, it was confirmed that an integrated microstructure (cell) having a relatively high surface charge density and having relatively uniform nano-sized unevenness was formed on the surface. The average interval between adjacent concave portions and between convex portions was about 28 nm, and the diameter of the concave portions was 0.1 to 30 nm. Further, the height difference of the unevenness was 0.1 to 30 nm, and was 23 nm on average. Also, from FIG. 1B, the work function is 13.35 eV [= 7.7 (from FIG. 1B) +5.65 (Pt work function)]. Note that the absolute value of the work function must be obtained by adding the work function value (5.65 eV in this case) of the probe material Pt to the potential of 0 V at the time of measurement.

  This electricity storage material was made into a size of 1 mm × 10 mm, copper electrodes were fixed on the upper and lower surfaces thereof, and the DC charge / discharge characteristics were measured with a potentiostat / galvanostat. In the measurement, first, the battery was charged to 10 V at 1 nA, and spontaneous discharge was performed at an internal resistance of 2 TΩ for 5 minutes. After charging in the same manner, measurement of constant current discharge at 3 nA was also performed. FIG. 2 shows the measurement results. As shown in FIG. 2, after charging to 10 V, the discharge continued for 5 minutes in spontaneous discharge and about 0.5 seconds in constant current discharge. It is considered that the charging time is shortened and the discharging time is increased by increasing the charging current value.

  Next, this power storage material was made to have a size of 1 mm × 10 mm, and copper electrodes were fixed to the upper and lower surfaces thereof, and frequency characteristics were measured. In the measurement, a Nyquist diagram, a Bode diagram (impedance diagram, phase diagram), and a capacitance diagram of the AC impedance in a frequency range of 1 mHz to 1 GHz are obtained, and are shown in FIGS. 3 (a) to 3 (d), respectively. As shown in FIG. 3A, a Nyquist diagram substantially perpendicular to the imaginary axis is obtained. When the frequency increases, the phase hardly changes at -90 ° (see FIG. 3C), and the capacitance decreases to 300 MHz and shows a constant value at frequencies higher than that (see FIG. 3D). ) Was confirmed. Such a frequency characteristic shows the same characteristic as a simple series equivalent circuit of the resistor R and the capacitance C, and it can be said that the power storage material is a series power storage body.

Next, the surface area (Surface Area) of this electricity storage material was set to 150, 300, 450, and 600 mm ² , each was charged to 10 V at 1 nA, and spontaneous discharge was performed at an internal resistance for 5 minutes. After charging in the same manner, measurement of constant current discharge at 3 nA was also performed. The measurement results are shown in FIGS. 4A and 4B, respectively. FIG. 4C shows the amount of discharge with respect to the increase in surface area. As shown in FIGS. 4A and 4B, in both the spontaneous discharge and the constant current discharge, the discharge amount increases as the surface area increases, and as shown in FIG. 4C, the laminating effect was observed. . From this, it can be said that the surface of this electricity storage material is an electric distributed constant circuit in which countless capacitors are connected in parallel.

  Next, when the red LED of 2 V-100 μA was turned on using the discharge from the power storage material, continuous lighting for 0.3 ms was confirmed. In addition, even if it is a polymer of the formula (3) in which a carbonyl group is connected as a side chain to both ends of the amorphous fluororesin represented by the formula (1) as an electricity storage material, the same results as in FIGS. Is considered to be obtained.

  As shown in FIG. 5, a power storage device composed of a laminate was manufactured by the MEMS method using the power storage material of Example 1. First, a Cr (thickness: 20 nm) / Cu layer (thickness: 500 nm) is formed on the surface of a glass substrate (20 × 20 × 0.5 mm) by sputtering (see FIG. 5A), and a polyimide layer (thickness: 5 μm) and dried at 150 ° C. (see FIG. 5B). Next, an electricity storage material (thickness: 10 μm) is coated on the polyimide layer by spin coating, dried at 200 ° C. (see FIG. 5C), and a nanometer-sized uneven surface is dry-etched (FIG. 5C). An Al layer (thickness: 500 nm) was formed thereon by sputtering (see FIG. 5D). Finally, the glass substrate was removed (see FIG. 5 (f)), which was used as one power storage layer (see FIG. 5 (g)), and a plurality of the power storage layers were laminated with an insulator interposed therebetween. (See FIG. 5 (h)).

In this way, the laminated body thus produced is one in which the power storage materials of the respective power storage layers are joined in parallel, with the Al layer of the uppermost power storage layer and the Cu layer of the lowermost power storage layer as terminals. . That is, as shown in FIG. 5 (i), an electric distribution constant circuit composed of a simple parallel equivalent circuit of C and R is provided. Therefore, for example, a stacked body in which 100 power storage layers are stacked has 100 times the capacity of one power storage layer. Note that the Al layer and the Cu layer each preferably cover the entire surface of the power storage material.

Claims (4)

Electron affinity seen contains the above elements 290kJ / mol, (1) at both ends of the amorphous fluorine resin represented by formula, it consists of amorphous polymers aminosilyl group or a carbonyl group is connected as a side chain, to the surface, diameter It has a plurality of irregularities having a height of 0.1 to 30 nm and a height difference of 0.1 to 30 nm, an electric resistivity of 1 GΩcm or more, a work function of 9 to 14 eV, and a water absorption of less than 0.01%. Electricity storage material.
An electricity storage device comprising the electricity storage material according to claim 1 . The power storage device according to claim 2 , wherein the power storage material is in the form of a thin film, and includes a power storage body having a pair of metal electrodes provided on both surfaces of the power storage material so as to sandwich the power storage material. The power storage device according to claim 3 , wherein the power storage device includes a stacked body in which a plurality of the power storage bodies are stacked.