WO2015012100A1 - Solid ion capacitor - Google Patents

Solid ion capacitor Download PDF

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Publication number
WO2015012100A1
WO2015012100A1 PCT/JP2014/068216 JP2014068216W WO2015012100A1 WO 2015012100 A1 WO2015012100 A1 WO 2015012100A1 JP 2014068216 W JP2014068216 W JP 2014068216W WO 2015012100 A1 WO2015012100 A1 WO 2015012100A1
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Prior art keywords
solid electrolyte
solid
ion
ion conductive
anode
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PCT/JP2014/068216
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French (fr)
Japanese (ja)
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聡史 横溝
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株式会社村田製作所
エナジー・ストレージ・マテリアルズ合同会社
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Publication of WO2015012100A1 publication Critical patent/WO2015012100A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/46—Metal oxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/04—Hybrid capacitors
    • H01G11/06—Hybrid capacitors with one of the electrodes allowing ions to be reversibly doped thereinto, e.g. lithium ion capacitors [LIC]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/50—Electrodes characterised by their material specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/56—Solid electrolytes, e.g. gels; Additives therein
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

  • the present invention relates to a solid ion capacitor, and more particularly to a solid ion capacitor that stores electricity using a solid electrolyte.
  • the electric double layer capacitor utilizes the fact that when a voltage is applied, an extremely thin electric double layer is formed between the anode or the cathode and the electrolyte. Accumulated and discharged, the charged particles return to the state prior to charging, so there is no heat generation or deterioration even when repeated charging / discharging without using chemical reactions, and high efficiency and rapid charging / discharging is possible. It is considered possible to obtain excellent cycle characteristics.
  • Patent Document 1 proposes an all-solid-state electric double layer capacitor that includes a solid electrolyte and a current collector, and in which the solid electrolyte is an inorganic solid electrolyte.
  • Patent Document 1 a Li ion conductive compound having a NASICON type crystal structure represented by Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 is used, and the Li ion conductive compound is mainly used. A solid electrolyte having a diameter of 14.5 mm and a thickness of 0.97 mm is produced. Then, electrodes made of Au are formed on both surfaces of the solid electrolyte, and an all solid-state electric double layer capacitor having a capacitance of 20 ⁇ F is obtained.
  • JP 2008-130844 (Claim 1, paragraph numbers [0050] to [0051], Table 1, etc.)
  • the Li ion conductive compound having a NASICON crystal structure as in Patent Document 1 when a voltage is applied between the anode and the cathode at the time of charging, the anion exists in the crystal lattice and does not move, only the cation. Therefore, the region to which an electric field is applied (hereinafter referred to as “electric field application region”) is not shielded unlike an electric double layer capacitor, and an increase in the electric field application region is expected. .
  • the liquid electrolyte acts as a mere conductor in parts other than the ultrathin electric double layer, and the cation is attracted to the anion near the anode. Is attracted to cations near the cathode. For this reason, the electric field application region is stopped in the vicinity of each of the anode and the cathode, and is shielded so as not to enter the liquid electrolyte. Therefore, it is difficult to increase the electric field application region.
  • Patent Document 1 does not move because the anion exists in the crystal lattice as described above, and only the cation moves. As a result, an increase in the electric field application region can be expected. Then, since the polarization is increased by the electric charge moved by the electric field, it is considered that the electric charge accumulated in the anode and the cathode is increased, and the capacitance per volume can be increased.
  • the thickness of the solid electrolyte is as large as 0.97 mm. Therefore, the electric field application area per volume in the solid electrolyte cannot be increased, and an electric current is not supplied to the interface between the anode and the cathode and the solid electrolyte. The state in which the multilayer is formed is maintained. For this reason, the voltage applied during charging is applied only to the electric double layer, making it difficult to obtain a desired large capacitance.
  • the present invention has been made in view of such circumstances, and provides a solid ion capacitor which can obtain a small size and a large capacitance by using a thin-film solid electrolyte and which has good cycle characteristics.
  • the purpose is to do.
  • the present inventor has conducted extensive research by forming electrodes on both main surfaces of a thinned solid electrolyte, and by interposing a material layer containing an ion conductive element between the solid electrolyte and the electrode.
  • the inventors have obtained the knowledge that deterioration of cycle characteristics can be suppressed while securing a large capacitance.
  • the present invention has been made based on such knowledge, and the solid ion capacitor according to the present invention is a solid ion capacitor in which electrodes are formed on both main surfaces of the solid electrolyte, and the solid electrolyte is a thin film. And a substance layer containing an ion-conducting element and interposed between the solid electrolyte and the electrode.
  • the material layer preferably has a thickness of 50 to 100 nm.
  • the ion conductive element contained in the material layer is the same as the ion conductive element contained in the ion conductive compound.
  • the ion conductive element is Li.
  • the ion conductive compound contains a NASICON crystal phase and at least contains Li, Al, P, and O.
  • the ion conductive compound contains a glass component.
  • the solid electrolyte made of glass ceramic containing a glass component exhibits good stability against moisture, it is possible to realize a solid ion capacitor having excellent moisture absorption resistance.
  • the electrode is formed of a non-valve action material having no valve action.
  • an insulating layer is not formed at the interface between the solid electrolyte and the electrode, ion conductivity can be ensured, and a large amount of desired charges can be accumulated in the electrode.
  • the non-valve action material is a noble metal material, a transition metal material, an oxide material, a semiconductor material, or a combination thereof.
  • a solid ion capacitor having electrodes formed on both main surfaces of the solid electrolyte, the solid electrolyte being formed of a thin film body and containing an ion conductive compound,
  • the material layer containing the ion conductive element is interposed at the interface between the solid electrolyte and the electrode, an electric field is applied to the entire solid electrolyte, and the charge near the electrode is near the opposite electrode. Therefore, extremely large polarization occurs, the charge accumulated in the anode and the cathode increases, and the capacitance can be greatly increased.
  • the material layer containing the ion conductive element is interposed at the interface between the solid electrolyte and the electrode, even if the ion conductive element in the ion conductive compound moves to the electrode side during charge and discharge, It is possible to suppress the ion conductive element from participating in an unintended irreversible chemical reaction at the interface, and thereby obtain a solid ion capacitor having good cycle characteristics with little decrease in capacitance even after repeated charge and discharge. Can do.
  • FIG. 1 is a cross-sectional view schematically showing an embodiment of a solid ion capacitor according to the present invention.
  • the solid ion capacitor has an anode 2 a and a cathode 2 b (electrode) on both main surfaces of a solid electrolyte 1. Is formed.
  • the solid electrolyte 1 is formed of a thin film body, and includes ion conductive compounds and material layers 3a and 3b (hereinafter referred to as “specific element-containing material layers”) containing an ion conductive element. 1 and the anode 2a and the cathode 2b, respectively.
  • the solid electrolyte 1 into a thin film body, a large electrostatic capacity can be obtained, and the specific element-containing material layers 3a and 3b are interposed between the solid electrolyte 1 and the anode 2a and the cathode 2b.
  • the specific element-containing material layers 3a and 3b are interposed between the solid electrolyte 1 and the anode 2a and the cathode 2b.
  • the capacitance in the conventional electric double layer capacitor, a voltage is applied only to a portion forming the electric double layer to accumulate electric charge, and the capacitance does not depend on the thickness of the electrolyte, so that the capacitance is increased. For this purpose, it is necessary to increase the electrode area. However, since there is a limit in increasing the electrode area, the capacitance can be obtained only about 25 ⁇ F / cm 2 in terms of specific capacity.
  • the solid ion capacitor of the present invention can increase the electric field application region in the solid electrolyte 1 by reducing the thickness of the solid electrolyte 1, and thereby electrostatically increase the electrode area without increasing the electrode area.
  • the capacity can be greatly increased.
  • FIG. 2A and 2B are diagrams for explaining the operation principle of the solid ion capacitor.
  • FIG. 2A is a diagram schematically showing the solid ion capacitor
  • FIG. 2B is an equivalent circuit of FIG. 2A.
  • FIG. 2 (c) shows the potential distribution of FIG. 2 (a), respectively.
  • the solid electrolyte 1 only one of a cation or an anion moves in the solid, and the other ion forms a crystal lattice and does not move.
  • the solid electrolyte 1 is formed of a cation conductive compound containing a cation such as Li ion, the cation moves in the solid electrolyte 1 even when a voltage is applied between the anode 2a and the cathode 2b.
  • anions do not move easily from the crystal lattice.
  • the potential distribution of the solid ion capacitor decreases substantially linearly from the anode 2a to the cathode 2b, and no flat portion is formed in the solid electrolyte 1, or the pole Only a short distance flat part is formed.
  • the electric field application region can be increased by thinning the thickness of the solid electrolyte 1, and a single capacitor C is formed between the anode 2a and the cathode 2b with the solid electrolyte 1 interposed therebetween. It becomes possible to do. Further, since the polarization formed by the ions displaced by the electric field increases due to the increase in the electric field application region, the charges accumulated in the anode 2a and the cathode 2b increase, thereby greatly increasing the capacitance per volume. It becomes possible to make it.
  • the thickness of the solid electrolyte 1 is not particularly limited as long as it is a thin film body that can secure a sufficient electric field application region when the electric field penetrates into the solid electrolyte 1 when an electric field is applied. It is preferable to form the following.
  • the material for forming the solid electrolyte 1 is not particularly limited as long as it includes an ion conductive compound in which ions move in the solid electrolyte 1, but the apex of the regular octahedral structure and the regular tetrahedral structure are not limited. It is preferable to include a NASICON crystal structure in which the apex is shared and arranged three-dimensionally.
  • the NASICON crystal structure has large voids in the crystal structure, and the cation moves easily, while the movement of the anion is extremely difficult.
  • a mixed phase of NASICON crystal structure and AlPO 4 (berlinite) is more preferable.
  • Li can be preferably used as the ion conductor element, and other components of the ion conductor compound are preferably used in the form of complex oxides containing Al, P, Ti, Ge, and the like. can do.
  • Ceramics containing Li usually have hygroscopicity and are unstable with respect to moisture, but by containing a glass component, they show good stability with respect to moisture and improve moisture resistance. be able to.
  • the specific element-containing material layers 3a and 3b are respectively interposed between the solid electrolyte 1 and the anode 2a and the cathode 2b, so that a decrease in capacitance is suppressed even when charging and discharging are repeated. A solid ion capacitor with good cycle characteristics is obtained.
  • the ion conductive element contained in the solid electrolyte 1 is charged and discharged. Even if it moves to the anode 2a and the cathode 2b side at times, it is possible to suppress as much as possible that the ion conductive element participates in an unintended irreversible chemical reaction at the interface between the anode 2a and the cathode 2b. However, it is possible to obtain a solid ion capacitor with good cycle characteristics with little decrease in capacitance.
  • the specific element-containing material layers 3a and 3b are not particularly limited as long as they contain an ion conductive element.
  • the ion conduction contained in the ion conductive compound in the solid electrolyte 1 is used.
  • the material containing the same element as the ionic element for example, the ion conductive element contained in the ion conductive compound in the solid electrolyte 1 is Li, Li or a Li compound containing Li is preferably used.
  • the specific element-containing material layers 3a and 3b are only required to be present between the solid electrolyte 1 and the anode 2a and cathode 2b, and the thickness thereof is not particularly limited. In order to maintain a large capacitance that is not inferior to the initial value even if the above is repeated, the thickness is preferably 50 to 100 nm.
  • the electrode material used for the anode 2a and the anode 2b is not particularly limited, but a non-valve action material having no valve action, for example, a noble metal material such as Au, Pt, Pd, Ni, Cu, Cr, Transition metal materials such as Mn, Fe, and Co can be used preferably, and oxide materials and semiconductor materials such as SiC can also be used.
  • a noble metal material such as Au, Pt, Pd, Ni, Cu, Cr, Transition metal materials such as Mn, Fe, and Co
  • oxide materials and semiconductor materials such as SiC can also be used.
  • valve action metal having a valve action such as Al, Ti, Ta, Nb, or an alloy containing these metals can be easily applied to the interface between the anode 2a or the anode 2b and the solid electrolyte 1 during the production of the solid ion capacitor. This is not preferable because an insulating layer may be formed and the capacitance may be reduced.
  • the interface between the solid electrolyte 1 and the specific element-containing material layers 3a and 3b has a micro uneven structure.
  • the electrode areas of the anode 2a and the cathode 2b joined to the specific element-containing material layers 3a and 3b are increased, so that the capacitance can be further increased in combination with the thinning of the solid electrolyte 1. It becomes possible.
  • the surface Since the solid electrolyte 1 is a sintered body formed by a firing process as will be described later, the surface has a certain uneven structure at the stage of sintering. After the polishing process is performed so that the surface has minute irregularities, the specific element-containing material layers 3a and 3b are formed, or the specific element-containing material layers 3a and 3b are formed without polishing the sintered body.
  • the interface can be easily made into a micro uneven structure.
  • the main surface of the solid electrolyte 1 can be appropriately etched to form a micro uneven structure.
  • a predetermined amount of raw materials are weighed and mixed.
  • the raw material is a Li compound such as Li 2 CO 3 , AlPO 4 or H 3
  • a P compound such as PO 4 and a Ti compound such as TiO 2 are prepared, and a predetermined amount of these raw materials are weighed and mixed to obtain a mixture.
  • this mixture is heat-treated with a predetermined heat-treatment profile to produce an ion conductive compound.
  • a predetermined amount of a glass material containing a Si compound such as SiO 2 is weighed and mixed together with the raw materials, heated and melted, and then rapidly cooled to be vitrified. Then, it is preferable to heat-treat with the predetermined heat treatment profile to produce an ion conductive compound.
  • the ion conductive compound is pulverized by a wet process, and then a binder, a solvent, a plasticizer, and the like are added and sufficiently mixed by a wet process to obtain a slurry. And after drying and granulating this slurry, it press-molds to a pellet shape etc. and obtains the molded object of a thin film.
  • the binder, solvent, plasticizer, etc. are not particularly limited.
  • polyvinyl butyral resin is used as the binder
  • n-butyl acetate is used as the solvent
  • dibutyl phthalate is used as the plasticizer. can do.
  • the molded body is fired, for example, by setting the firing temperature to 400 ° C. to 1250 ° C. and the firing time to 3 to 70 hours, thereby producing the solid electrolyte 1 having a thin film body (for example, a thickness of 200 ⁇ m or less). To do.
  • an ion conductive material containing an ion conductive element such as Li or a Li compound, is prepared. Then, a specific element-containing material layer is formed on both main surfaces of the solid electrolyte 1 using a thin film forming method such as a vacuum deposition method or a plating method such as electrolytic plating.
  • a non-valve action material having no valve action for example, noble metal material such as Au, Pt, Pd, transition metal material such as Ni, Cu, Cr, Mn, Fe, Co, oxide
  • noble metal material such as Au, Pt, Pd, transition metal material such as Ni, Cu, Cr, Mn, Fe, Co, oxide
  • a semiconductor material such as SiC, is prepared, and this electrode material is used to produce the anode 2a and the cathode 2b on both main surfaces of the solid electrolyte 1, thereby producing a solid ion capacitor.
  • the formation method of the anode 2a and the cathode 2b is not particularly limited.
  • a thin film formation method such as a sputtering method or a vacuum evaporation method, a coating method in which a paste is applied and baked, a plating method such as electrolytic plating, or thermal spraying. Any method can be used.
  • the solid electrolyte 1 is formed of a thin film body, the ion conductive compound is contained, and the specific element-containing material layers 3a and 3b containing the ion conductive element are the solid electrolyte 1. Since it is interposed at the interface between the anode 2a and the cathode 2b, a large capacitance can be obtained, and a solid ion capacitor having good cycle characteristics can be obtained.
  • this invention is not limited to the said embodiment, It can deform
  • a single plate-shaped solid ion capacitor is illustrated, but it is also preferable to have a multilayer structure similar to a multilayer ceramic capacitor. That is, the solid electrolyte and the specific element are contained so that the specific element-containing material layer and the anode are formed on one main surface of the thin-film solid electrolyte, and the specific element-containing material layer and the cathode are formed on the other main surface.
  • a capacitor body composed of a material layer, an anode, and a cathode is laminated to form a capacitor body, and external electrodes are formed on both ends of the capacitor body to form a multilayer structure similar to a multilayer ceramic capacitor.
  • a small solid ion capacitor having a larger capacitance and good cycle characteristics can be easily realized.
  • Example preparation [Sample Nos. 2 to 4] H 3 PO 4 , Li 2 CO 3 , Al (PO 3 ) 3 , SiO 2 , and TiO 2 were prepared as raw materials, and a predetermined amount of these raw materials were weighed and mixed to obtain a mixture.
  • this mixture is put into a melting kiln, heated and melted at a temperature of 1500 ° C. for 3 hours, and the melted mixture is poured out from a slit-like hole provided at the bottom of the melting kiln to a mold at a temperature of 300 ° C. And rapidly cooled to obtain a glassy molded body.
  • this glassy molded body was heat-treated with a predetermined heat treatment profile to obtain a Li ion conductive compound.
  • the temperature of the heat treatment furnace is increased from room temperature to 600 ° C. at a temperature increase rate of 300 ° C./h, then increased to 950 ° C. at a temperature increase rate of 100 ° C./h, and then the heat treatment temperature is increased to 950 ° C. It was set and held for 10 hours, and then gradually cooled to room temperature, whereby a crystallized Li ion conductive compound was obtained.
  • the component composition of the Li-ion conductive compound was measured using an ICP emission spectrometer (Thermo Fisher Scientific Inc. ICAP6300), the composition is a Li 1.21 Al 0.64 Ti 1.53 Si 0.16 P 2.82 O 12 It was confirmed.
  • Li ion conductive compound is pulverized wet
  • polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer are added and thoroughly mixed in a wet manner. A slurry was obtained. And after drying and granulating this slurry, it press-molded and produced the molded object.
  • the molded body was fired at a firing temperature of 800 ° C. for 12 hours to obtain a sintered body.
  • this sintered body was cut with a diamond cutter so as to have a thickness of 160 ⁇ m, and the surface was mirror-finished by mechanical polishing, thereby obtaining a solid electrolyte.
  • metal Li was deposited on the surface of the solid electrolyte to form a metal Li layer (specific element-containing material layer) having a thickness of 10 to 100 nm.
  • Pt was prepared as an anode material and a cathode material, vacuum deposition was used, and Pt was deposited on the surface of the metal Li layer to form an anode and a cathode each having a thickness of 200 nm. Four samples were obtained. The electrode surface areas of the anode and the cathode were each 0.25 cm 2 .
  • Sample No. 1 was prepared in the same manner and procedure as Sample Nos. 2 to 4, except that the anode and cathode were directly formed on both main surfaces of the solid electrolyte.
  • Example No. 5 A solid electrolyte was produced by the same method and procedure as Sample Nos. 2-4.
  • Pt is prepared as an anode material and a cathode material
  • Pt is used as a target
  • both main surfaces of the solid electrolyte are subjected to sputtering treatment, whereby the first anode and the first cathode made of Pt and having a thickness of 200 nm are made solid. It was formed on both main surfaces of the electrolyte.
  • metal Li was vapor-deposited on the surfaces of the first anode and the first cathode to form a metal Li layer having a thickness of 50 nm.
  • sample evaluation The samples Nos. 1 to 5 were charged and discharged with a predetermined charge / discharge profile using a constant voltage charge / discharge characteristic evaluation apparatus.
  • FIG. 3 is a diagram showing the charge / discharge profile used in this example, where the horizontal axis represents time (minutes) and the vertical axis represents applied voltage (V).
  • a constant voltage of 2.5 V was applied between the anode and the cathode, charged for 30 minutes, then discharged for 30 minutes, and the anode and cathode were short-circuited for another 60 minutes to maintain the discharge state.
  • a charge / discharge cycle of applying a constant voltage of 0.5 V between the anode and the cathode and charging for 30 minutes was repeated 10 times.
  • the short-circuit time is provided in order to prevent the measurement of the capacitance in the next cycle from being affected.
  • FIG. 4 shows current characteristics during charging and discharging, where the horizontal axis is time (minutes) and the vertical axis is current (a.u).
  • the specific capacity was obtained by integrating the current value at the time of discharge with time from this current characteristic, converting it to electric charge, calculating the electrostatic capacity from the amount of electric charge, and further dividing this electrostatic capacity by the electrode surface area.
  • the specific capacity change rate ⁇ Cn after n cycles was obtained from the initial value C1 of the specific capacity and the specific capacity Cn after n cycles, and the cycle characteristics were evaluated.
  • n 1-10.
  • Table 1 shows the thickness and position of the metallic Li layer, the initial value C1 of the specific capacity, and the specific capacity change rate ⁇ C 10 after 10 cycles in sample numbers 1 to 5.
  • the initial value C1 of the specific capacity is 1013 to 1158 ⁇ F / cm 2 , which is a large specific capacity of 1000 ⁇ F / cm 2 or more. I was able to get it.
  • Sample No. 1 had a specific capacity change rate ⁇ C 10 of 74.6%, and the specific capacity decreased greatly after 10 cycles. This is because the solid electrolyte and the anode and cathode are in direct contact with each other at the interface, so that Li contained in the solid electrolyte moves to the electrode or the interface between the electrode and the solid electrolyte with an irreversible reaction during charge and discharge. Impurities are generated, and as a result, repeated charge / discharge is considered to reduce the capacitance.
  • the specific capacity change rate ⁇ C 10 can be suppressed by interposing the metal Li layer between the solid electrolyte and the anode and the cathode. However, as the thickness of the metal Li layer increases, the specific capacity change rate ⁇ C 10 is reduced. It was also found that it can be further suppressed.
  • FIG. 5 is a characteristic diagram showing cycle characteristics of sample numbers 1 to 5.
  • the horizontal axis indicates the number of cycles n, and the vertical axis indicates the change rate ⁇ Cn (%) of the specific capacity.
  • the symbol ⁇ indicates the cycle characteristics of sample number 1
  • the symbol ⁇ indicates the sample number 2
  • symbol ⁇ indicates the sample number 3
  • symbol ⁇ indicates the sample number 4
  • symbol ⁇ indicates the cycle characteristic.
  • the specific capacity decreased to about 90% of the initial value in the second cycle, and the specific capacity decreased significantly as the number of charge / discharge cycles increased. Yes.
  • Sample Nos. 2 to 4 of the present invention suppressed the decrease in specific capacity even after repeated charge and discharge, and Sample Nos. 3 and 4 having a metal Li layer of 50 to 100 nm repeated charge / discharge cycles. However, it was found that the specific capacity can be maintained as high as the initial value C1.
  • Example is only an example which actualized this invention, and is not limited to this Example.
  • the same effect can be obtained even if an element such as Ge is added in addition to Ti or instead of Ti.
  • a solid ion capacitor having a large capacitance and good cycle characteristics can be realized.

Abstract

A positive electrode (2a) and a negative electrode (2b) are formed on the two principal surfaces of a solid electrolyte (1). The solid electrolyte (1) is preferably formed into a 200μm or thinner thin film body, and contains a Li ion- or other ion-conductive compound. Further, ion conductive material layers (3a, 3b), e.g., metal Li layers, that contain the Li ion- or other ion-conductive compound are interposed at the interface between the solid electrolyte (1) and the positive electrode (2a), and at the interface between the solid electrolyte (1) and the negative electrode (2b). The ion conductive material layers (3a, 3b) are preferably 50-100nm thick. Use of the thin-film solid electrolyte makes it possible to achieve a large static capacitance despite the small size and a solid ion capacitor with excellent cycle characteristics.

Description

固体イオンキャパシタSolid ion capacitor
　本発明は、固体イオンキャパシタに関し、より詳しくは、固体電解質を使用して蓄電する固体イオンキャパシタに関する。 The present invention relates to a solid ion capacitor, and more particularly to a solid ion capacitor that stores electricity using a solid electrolyte.
　携帯電話、ノートパソコン、デジタルカメラ等の各種電子機器の普及に伴い、これら電子機器のコードレス電源として、各種蓄電デバイスの研究・開発が盛んに行われている。そして、これら蓄電デバイスのうち、電気二重層キャパシタは、高速充放電が可能であり、充放電を繰り返しても性能の劣化が少ないことから、パソコンメモリ等のバックアップ電源やハイブリッド自動車等の補助電源などの用途に広く用いられている。 With the widespread use of various electronic devices such as mobile phones, laptop computers, and digital cameras, various types of power storage devices have been actively researched and developed as cordless power sources for these electronic devices. Of these electricity storage devices, the electric double layer capacitor can be charged / discharged at high speed, and its performance is less deteriorated even after repeated charge / discharge. Therefore, backup power sources such as personal computer memory, auxiliary power sources such as hybrid vehicles, etc. It is widely used for applications.
　上記電気二重層キャパシタは、電圧を印加すると陽極又は陰極と電解質との間に極薄の電気二重層が形成されることを利用したものであり、充電中に電気二重層を形成して電荷を蓄積し、放電によって荷電粒子は充電前の状態に戻ることから、化学反応を利用せず、繰り返し充放電を行っても発熱や劣化がなく、高効率で急速な充放電が可能であり、良好なサイクル特性を得ることが可能と考えられる。 The electric double layer capacitor utilizes the fact that when a voltage is applied, an extremely thin electric double layer is formed between the anode or the cathode and the electrolyte. Accumulated and discharged, the charged particles return to the state prior to charging, so there is no heat generation or deterioration even when repeated charging / discharging without using chemical reactions, and high efficiency and rapid charging / discharging is possible. It is considered possible to obtain excellent cycle characteristics.
　そして、特許文献１には、固体電解質と、集電体とを備え、前記固体電解質が無機固体電解質である全固体型電気二重層キャパシタが提案されている。 Patent Document 1 proposes an all-solid-state electric double layer capacitor that includes a solid electrolyte and a current collector, and in which the solid electrolyte is an inorganic solid electrolyte.
　この特許文献１では、液体電解質（電解液）を使用すると、漏液により劣化が生じるおそれがあることから、無機化合物からなる固体電解質を使用し、これにより漏液が生じるのを回避している。 In this patent document 1, when a liquid electrolyte (electrolytic solution) is used, there is a possibility of deterioration due to liquid leakage. Therefore, a solid electrolyte made of an inorganic compound is used, thereby avoiding liquid leakage. .
　すなわち、この特許文献１では、Ｌｉ1.3Ａｌ0.3Ｔｉ1.7（ＰＯ４）３で表わされるナシコン（ＮＡＳＩＣＯＮ）型結晶構造を有するＬｉイオン伝導性化合物を使用し、該Ｌｉイオン伝導性化合物を主体とする直径が１４．５ｍｍ、厚みが０．９７ｍｍの固体電解質を作製している。そして、この固体電解質の両面にＡｕ製の電極を形成し、静電容量が２０μＦの全固体型電気二重層コンデンサーを得ている。 That is, in Patent Document 1, a Li ion conductive compound having a NASICON type crystal structure represented by Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 is used, and the Li ion conductive compound is mainly used. A solid electrolyte having a diameter of 14.5 mm and a thickness of 0.97 mm is produced. Then, electrodes made of Au are formed on both surfaces of the solid electrolyte, and an all solid-state electric double layer capacitor having a capacitance of 20 μF is obtained.
特開２００８－１３０８４４号公報（請求項１、段落番号〔００５０〕～〔００５１〕、表１等）JP 2008-130844 (Claim 1, paragraph numbers [0050] to [0051], Table 1, etc.)
　特許文献１のようなナシコン型結晶構造を有するＬｉイオン伝導性化合物では、充電時に陽極及び陰極との間に電圧を印加すると、陰イオンは結晶格子中に存在して移動せず、陽イオンのみが移動することから、電気二重層キャパシタのように、電界が印加される領域（以下、「電界印加領域」という。）が遮蔽されることもなく、これにより電界印加領域の増加が期待される。 In the Li ion conductive compound having a NASICON crystal structure as in Patent Document 1, when a voltage is applied between the anode and the cathode at the time of charging, the anion exists in the crystal lattice and does not move, only the cation. Therefore, the region to which an electric field is applied (hereinafter referred to as “electric field application region”) is not shielded unlike an electric double layer capacitor, and an increase in the electric field application region is expected. .
　すなわち、液体電解質を使用した従来の電気二重層キャパシタでは、極薄の電気二重層以外の部分では、液体電解質は単なる導電体として作用し、陽イオンは陽極近傍の陰イオンに引き寄せられ、陰イオンは陰極近傍の陽イオンに引き寄せられる。このため電界印加領域は陽極及び陰極の各近傍域に止められ、液体電解質の内部に浸入しないように遮蔽されることから、電界印加領域の増加は困難である。 That is, in a conventional electric double layer capacitor using a liquid electrolyte, the liquid electrolyte acts as a mere conductor in parts other than the ultrathin electric double layer, and the cation is attracted to the anion near the anode. Is attracted to cations near the cathode. For this reason, the electric field application region is stopped in the vicinity of each of the anode and the cathode, and is shielded so as not to enter the liquid electrolyte. Therefore, it is difficult to increase the electric field application region.
　これに対し特許文献１は、電圧を印加しても、上述したように陰イオンは結晶格子中に存在して移動せず、陽イオンのみが移動することから、電界印加領域の遮蔽もなく、これにより電界印加領域の増加が期待できる。そして、電界により移動する電荷によって分極が大きくなることから、陽極及び陰極に蓄積される電荷が増加し、体積当たりの静電容量を大きくすることができると考えられる。 On the other hand, even if a voltage is applied, Patent Document 1 does not move because the anion exists in the crystal lattice as described above, and only the cation moves. As a result, an increase in the electric field application region can be expected. Then, since the polarization is increased by the electric charge moved by the electric field, it is considered that the electric charge accumulated in the anode and the cathode is increased, and the capacitance per volume can be increased.
　しかしながら、特許文献１では、固体電解質の厚みが０．９７ｍｍと大きく、このため固体電解質中の体積当たりの電界印加領域を増加させることができず、陽極及び陰極と固体電解質との界面に電気二重層が形成された状態を維持する。このため充電時に印加される電圧は、電気二重層のみに負荷されることとなり、所望の大きな静電容量を得るのが困難となる。 However, in Patent Document 1, the thickness of the solid electrolyte is as large as 0.97 mm. Therefore, the electric field application area per volume in the solid electrolyte cannot be increased, and an electric current is not supplied to the interface between the anode and the cathode and the solid electrolyte. The state in which the multilayer is formed is maintained. For this reason, the voltage applied during charging is applied only to the electric double layer, making it difficult to obtain a desired large capacitance.
　したがって、大きな静電容量を得るためには固体電解質を薄膜化すればよいと考えられるが、本発明者の研究結果により、固体電解質を薄膜化しても、充放電を繰り返すと静電容量の低下が顕著となり、良好なサイクル特性を確保できないことが分かった。 Therefore, in order to obtain a large capacitance, it is considered that the solid electrolyte needs to be thinned. However, according to the research results of the present inventor, even if the solid electrolyte is thinned, the capacitance decreases when charging and discharging are repeated. It became clear that good cycle characteristics could not be secured.
　本発明はこのような事情に鑑みなされたものであって、薄膜の固体電解質を使用することにより、小型で大きな静電容量を得ることができ、かつ良好なサイクル特性を有する固体イオンキャパシタを提供することを目的とする。 The present invention has been made in view of such circumstances, and provides a solid ion capacitor which can obtain a small size and a large capacitance by using a thin-film solid electrolyte and which has good cycle characteristics. The purpose is to do.
　本発明者は、薄膜化された固体電解質の両主面に電極を形成して鋭意研究を行なったところ、固体電解質と電極との間にイオン伝導性元素を含有した物質層を介在させることにより、大きな静電容量を確保しつつ、サイクル特性の劣化を抑制できるという知見を得た。 The present inventor has conducted extensive research by forming electrodes on both main surfaces of a thinned solid electrolyte, and by interposing a material layer containing an ion conductive element between the solid electrolyte and the electrode. The inventors have obtained the knowledge that deterioration of cycle characteristics can be suppressed while securing a large capacitance.
　本発明はこのような知見に基づきなされたものであって、本発明に係る固体イオンキャパシタは、固体電解質の両主面に電極が形成された固体イオンキャパシタであって、前記固体電解質は、薄膜体で形成されると共に、イオン伝導性化合物が含有され、かつイオン伝導性元素を含有した物質層が前記固体電解質と前記電極との界面に介在されていることを特徴としている。 The present invention has been made based on such knowledge, and the solid ion capacitor according to the present invention is a solid ion capacitor in which electrodes are formed on both main surfaces of the solid electrolyte, and the solid electrolyte is a thin film. And a substance layer containing an ion-conducting element and interposed between the solid electrolyte and the electrode.
　これにより固体電解質全体に電界が印加されるようになり、電極近傍の電荷が反対側の電極近傍まで移動できるため、極めて大きな分極が生ずることとなり、陽極及び陰極に蓄積される電荷が増加し、静電容量を大幅に増大させることが可能となる。しかも、イオン伝導性元素を含有した物質層が前記固体電解質と前記電極との界面に介在されているので、イオン伝導性化合物中のイオン伝導性元素が充放電時に電極側に移動しても、該イオン伝導性元素が前記界面で意図しない不可逆的な化学反応に関与するのを抑制でき、サイクル特性の劣化を抑制することができる。 As a result, an electric field is applied to the entire solid electrolyte, and the charge near the electrode can move to the vicinity of the opposite electrode, resulting in extremely large polarization, increasing the charge accumulated in the anode and cathode, The capacitance can be greatly increased. In addition, since the material layer containing the ion conductive element is interposed at the interface between the solid electrolyte and the electrode, even if the ion conductive element in the ion conductive compound moves to the electrode side during charge and discharge, It is possible to suppress the ion conductive element from participating in an unintended irreversible chemical reaction at the interface, and to suppress deterioration of cycle characteristics.
　また、本発明の固体イオンキャパシタは、前記物質層は、厚みが５０～１００ｎｍであるのが好ましい。 In the solid ion capacitor of the present invention, the material layer preferably has a thickness of 50 to 100 nm.
　これにより１０回程度の充放電を繰り返しても、初期値と遜色がない程度の大きな静電容量を維持することができる。 Thus, even if charging / discharging is repeated about 10 times, a large electrostatic capacity comparable to the initial value can be maintained.
　また、本発明の固体イオンキャパシタは、前記物質層に含有される前記イオン伝導性元素は、前記イオン伝導性化合物に含有されるイオン伝導性元素と同一であるのが好ましい。 In the solid ion capacitor of the present invention, it is preferable that the ion conductive element contained in the material layer is the same as the ion conductive element contained in the ion conductive compound.
　さらに、本発明の固体イオンキャパシタは、前記イオン伝導性元素が、Ｌｉであるのが好ましい。 Furthermore, in the solid ion capacitor of the present invention, it is preferable that the ion conductive element is Li.
　また、本発明の固体イオンキャパシタは、前記イオン伝導性化合物は、ナシコン型結晶相を含有すると共に、少なくともＬｉ、Ａｌ、Ｐ、及びＯを含んでいるのが好ましい。 In the solid ion capacitor of the present invention, it is preferable that the ion conductive compound contains a NASICON crystal phase and at least contains Li, Al, P, and O.
　これによりＯイオンが結晶格子に配された状態でＬｉイオンのみを移動させることができ、電界を効率良く増加させることができることから、静電容量の大幅増加を効果的に達成することが可能となる。 As a result, only Li ions can be moved in a state where O ions are arranged in the crystal lattice, and the electric field can be increased efficiently, so that it is possible to effectively achieve a significant increase in capacitance. Become.
　また、本発明の固体イオンキャパシタは、前記イオン伝導性化合物が、ガラス成分を含有しているのが好ましい。 In the solid ion capacitor of the present invention, it is preferable that the ion conductive compound contains a glass component.
　この場合は、ガラス成分を含んだガラスセラミックからなる固体電解質が、水分に対しても良好な安定性を示すことから、耐吸湿性に優れた固体イオンキャパシタを実現することが可能となる。 In this case, since the solid electrolyte made of glass ceramic containing a glass component exhibits good stability against moisture, it is possible to realize a solid ion capacitor having excellent moisture absorption resistance.
　また、本発明の固体イオンキャパシタは、前記電極が、弁作用を有さない非弁作用材料で形成されているのが好ましい。 In the solid ion capacitor of the present invention, it is preferable that the electrode is formed of a non-valve action material having no valve action.
　これにより固体電解質と電極との界面に絶縁層が形成されることもなく、イオン伝導性を確保することができ、所望の多くの電荷を電極に蓄積することができる。 Thus, an insulating layer is not formed at the interface between the solid electrolyte and the electrode, ion conductivity can be ensured, and a large amount of desired charges can be accumulated in the electrode.
　また、本発明の固体イオンキャパシタは、前記非弁作用材料が、貴金属材料、遷移金属材料、酸化物材料、及び半導体材料、又はこれらを組み合わせた材料であるのが好ましい。 In the solid ion capacitor of the present invention, it is preferable that the non-valve action material is a noble metal material, a transition metal material, an oxide material, a semiconductor material, or a combination thereof.
　本発明の固体イオンキャパシタによれば、固体電解質の両主面に電極が形成された固体イオンキャパシタであって、前記固体電解質は、薄膜体で形成されると共に、イオン伝導性化合物が含有され、かつイオン伝導性元素を含有した物質層が前記固体電解質と前記電極との界面に介在されているので、固体電解質全体に電界が印加されるようになり、電極近傍の電荷が反対側の電極近傍まで移動できるため、極めて大きな分極が生ずることとなり、陽極及び陰極に蓄積される電荷が増加し、静電容量を大幅に増大させることが可能となる。しかも、イオン伝導性元素を含有した物質層が前記固体電解質と前記電極との界面に介在されているので、イオン伝導性化合物中のイオン伝導性元素が充放電時に電極側に移動しても、該イオン伝導性元素が前記界面で意図しない不可逆的な化学反応に関与するのを抑制でき、これにより充放電を繰り返しても静電容量の低下が少ないサイクル特性の良好な固体イオンキャパシタを得ることができる。 According to the solid ion capacitor of the present invention, a solid ion capacitor having electrodes formed on both main surfaces of the solid electrolyte, the solid electrolyte being formed of a thin film body and containing an ion conductive compound, In addition, since the material layer containing the ion conductive element is interposed at the interface between the solid electrolyte and the electrode, an electric field is applied to the entire solid electrolyte, and the charge near the electrode is near the opposite electrode. Therefore, extremely large polarization occurs, the charge accumulated in the anode and the cathode increases, and the capacitance can be greatly increased. In addition, since the material layer containing the ion conductive element is interposed at the interface between the solid electrolyte and the electrode, even if the ion conductive element in the ion conductive compound moves to the electrode side during charge and discharge, It is possible to suppress the ion conductive element from participating in an unintended irreversible chemical reaction at the interface, and thereby obtain a solid ion capacitor having good cycle characteristics with little decrease in capacitance even after repeated charge and discharge. Can do.
本発明に係る固体イオンキャパシタの一実施の形態を模式的に示す断面図である。It is sectional drawing which shows typically one Embodiment of the solid ion capacitor which concerns on this invention. 固体イオンキャパシタの動作原理を示す図である。It is a figure which shows the principle of operation of a solid ion capacitor. 実施例における充放電サイクルの電圧プロファイルを示す図である。It is a figure which shows the voltage profile of the charging / discharging cycle in an Example. 実施例における放電電流の経時変化を示す図である。It is a figure which shows the time-dependent change of the discharge current in an Example. 実施例における各試料のサイクル特性を示す図である。It is a figure which shows the cycle characteristic of each sample in an Example.
　次に、本発明の実施の形態を詳説する。 Next, an embodiment of the present invention will be described in detail.
　図１は、本発明に係る固体イオンキャパシタの一実施の形態を模式的に示す断面図であって、該固体イオンキャパシタは、固体電解質１の両主面に陽極２ａ及び陰極２ｂ（電極）が形成されている。 FIG. 1 is a cross-sectional view schematically showing an embodiment of a solid ion capacitor according to the present invention. The solid ion capacitor has an anode 2 a and a cathode 2 b (electrode) on both main surfaces of a solid electrolyte 1. Is formed.
　そして、固体電解質１は、薄膜体からなると共に、イオン伝導性化合物が含有され、かつイオン伝導性元素を含有した物質層３ａ、３ｂ（以下、「特定元素含有物質層」という。）が固体電解質１と陽極２ａ及び陰極２ｂとの間にそれぞれ介在されている。 The solid electrolyte 1 is formed of a thin film body, and includes ion conductive compounds and material layers 3a and 3b (hereinafter referred to as “specific element-containing material layers”) containing an ion conductive element. 1 and the anode 2a and the cathode 2b, respectively.
　このように固体電解質１を薄膜体とすることにより、大きな静電容量を得ることができ、さらに固体電解質１と陽極２ａ及び陰極２ｂとの間に特定元素含有物質層３ａ、３ｂを介在させることにより、充放電を繰り返しても静電容量の低下が抑制されたサイクル特性の良好な固体イオンキャパシタを得ることができる。 Thus, by making the solid electrolyte 1 into a thin film body, a large electrostatic capacity can be obtained, and the specific element-containing material layers 3a and 3b are interposed between the solid electrolyte 1 and the anode 2a and the cathode 2b. Thus, it is possible to obtain a solid ion capacitor with good cycle characteristics in which a decrease in capacitance is suppressed even when charging and discharging are repeated.
　すなわち、従来の電気二重層キャパシタでは、電気二重層を形成している部分にのみ電圧が印加されて電荷が蓄積され、静電容量は電解質の厚みに依存しないことから、静電容量を増大させるためには電極面積を大きくする必要がある。しかし、電極面積を大きくするにも限界があることから、静電容量は、比容量に換算して２５μＦ／ｃｍ２程度しか得ることができなかった。 That is, in the conventional electric double layer capacitor, a voltage is applied only to a portion forming the electric double layer to accumulate electric charge, and the capacitance does not depend on the thickness of the electrolyte, so that the capacitance is increased. For this purpose, it is necessary to increase the electrode area. However, since there is a limit in increasing the electrode area, the capacitance can be obtained only about 25 μF / cm 2 in terms of specific capacity.
　これに対し本発明の固体イオンキャパシタは、固体電解質１の厚みを薄層化することにより、固体電解質１での電界印加領域を増加させることができ、これにより電極面積を増加させなくとも静電容量を大幅に増大させることが可能となる。 On the other hand, the solid ion capacitor of the present invention can increase the electric field application region in the solid electrolyte 1 by reducing the thickness of the solid electrolyte 1, and thereby electrostatically increase the electrode area without increasing the electrode area. The capacity can be greatly increased.
　図２は、上記固体イオンキャパシタの動作原理を説明する図であり、図２（ａ）は、固体イオンキャパシタを模式的に示した図、図２（ｂ）は図２（ａ）の等価回路、図２（ｃ）は図２（ａ）の電位分布をそれぞれ示している。 2A and 2B are diagrams for explaining the operation principle of the solid ion capacitor. FIG. 2A is a diagram schematically showing the solid ion capacitor, and FIG. 2B is an equivalent circuit of FIG. 2A. FIG. 2 (c) shows the potential distribution of FIG. 2 (a), respectively.
　固体電解質１では、固体中を陽イオン又は陰イオンのいずれか一方のイオンのみが移動し、他方のイオンは結晶格子を形成し、移動しない。例えば、固体電解質１がＬｉイオン等の陽イオンを含有した陽イオン伝導性化合物で形成されている場合、陽極２ａ及び陰極２ｂ間に電圧を印加しても、陽イオンは固体電解質１内を移動するが、陰イオンは結晶格子から容易には移動しない。したがって、固体電解質１を薄層化することにより、固体電解質１と陽極２ａ及び陰極２ｂとの界面には、電気二重層が形成され難くなり、電界印加領域は固体電解質１の内部にまで達する。すなわち、固体電解質１が薄層化されると、陽極２ａ及び陰極２ｂの近傍域において電界が遮蔽されることもなく、電界は固体電解質１の内部に侵入して電界印加領域が増加し、図２（ｂ）に示すように、単一のキャパシタＣを形成する。 In the solid electrolyte 1, only one of a cation or an anion moves in the solid, and the other ion forms a crystal lattice and does not move. For example, when the solid electrolyte 1 is formed of a cation conductive compound containing a cation such as Li ion, the cation moves in the solid electrolyte 1 even when a voltage is applied between the anode 2a and the cathode 2b. However, anions do not move easily from the crystal lattice. Therefore, by thinning the solid electrolyte 1, it becomes difficult to form an electric double layer at the interface between the solid electrolyte 1 and the anode 2 a and the cathode 2 b, and the electric field application region reaches the inside of the solid electrolyte 1. That is, when the solid electrolyte 1 is thinned, the electric field is not shielded in the vicinity of the anode 2a and the cathode 2b, and the electric field penetrates into the solid electrolyte 1 to increase the electric field application region. As shown in FIG. 2B, a single capacitor C is formed.
　この場合、固体イオンキャパシタの電位分布は、図２（ｃ）に示すように、陽極２ａから陰極２ｂに架けて略直線的に低下し、固体電解質１内では平坦部が形成されないか、又は極短距離の平坦部しか形成されない。 In this case, as shown in FIG. 2C, the potential distribution of the solid ion capacitor decreases substantially linearly from the anode 2a to the cathode 2b, and no flat portion is formed in the solid electrolyte 1, or the pole Only a short distance flat part is formed.
　このように固体イオンキャパシタでは、固体電解質１の厚みを薄層化することによって電界印加領域を増加させることができ、固体電解質１を挟んで陽極２ａ及び陰極２ｂ間で単一のキャパシタＣを形成することが可能となる。そして、電界印加領域の増加によって電界により変位するイオンにより形成される分極が増加することから、陽極２ａ及び陰極２ｂに蓄積される電荷が増加し、これにより体積当たりの静電容量を大幅に増大させることが可能となる。 As described above, in the solid ion capacitor, the electric field application region can be increased by thinning the thickness of the solid electrolyte 1, and a single capacitor C is formed between the anode 2a and the cathode 2b with the solid electrolyte 1 interposed therebetween. It becomes possible to do. Further, since the polarization formed by the ions displaced by the electric field increases due to the increase in the electric field application region, the charges accumulated in the anode 2a and the cathode 2b increase, thereby greatly increasing the capacitance per volume. It becomes possible to make it.
　そして、このような固体電解質１の厚みとしては、電界印加時に電界が固体電解質１の内部に浸入して十分な電界印加領域を確保できる薄膜体であれば特に限定されるものではないが、２００μｍ以下に形成するのが好ましい。 The thickness of the solid electrolyte 1 is not particularly limited as long as it is a thin film body that can secure a sufficient electric field application region when the electric field penetrates into the solid electrolyte 1 when an electric field is applied. It is preferable to form the following.
　また、固体電解質１を形成する材料としては、固体電解質１中をイオンが移動するイオン伝導性化合物を含んでいれば特に限定されるものではないが、正八面体構造の頂点と正四面体構造の頂点とが共有されて３次元的に配列されたナシコン型結晶構造を含むのが好ましい。ナシコン型結晶構造は、結晶構造中に大きな空隙を有し、陽イオンが容易に移動する一方、陰イオンの移動が極めて困難である。また、このようなイオン伝導性化合物の中でもナシコン型結晶構造とＡｌＰＯ４（ベルリナイト）との混合相がより好ましい。イオン伝導体元素としてはＬｉを好んで使用することができ、イオン伝導体化合物のその他の含有成分としては、Ａｌ、Ｐ、及びＴｉやＧｅ等を含有した複合酸化物形態のものを好んで使用することができる。 Further, the material for forming the solid electrolyte 1 is not particularly limited as long as it includes an ion conductive compound in which ions move in the solid electrolyte 1, but the apex of the regular octahedral structure and the regular tetrahedral structure are not limited. It is preferable to include a NASICON crystal structure in which the apex is shared and arranged three-dimensionally. The NASICON crystal structure has large voids in the crystal structure, and the cation moves easily, while the movement of the anion is extremely difficult. Further, among such ion conductive compounds, a mixed phase of NASICON crystal structure and AlPO 4 (berlinite) is more preferable. Li can be preferably used as the ion conductor element, and other components of the ion conductor compound are preferably used in the form of complex oxides containing Al, P, Ti, Ge, and the like. can do.
　さらに、イオン伝導性化合物としては、ＳｉＯ２等のガラス成分を含有したガラスセラミックを使用するのも好ましい。Ｌｉを含有したセラミックは、通常、吸湿性を有し、水分に対して不安定であるが、ガラス成分を含有させることにより、水分に対し良好な安定性を示し、耐吸湿性の向上を図ることができる。 Furthermore, it is also preferable to use a glass ceramic containing a glass component such as SiO 2 as the ion conductive compound. Ceramics containing Li usually have hygroscopicity and are unstable with respect to moisture, but by containing a glass component, they show good stability with respect to moisture and improve moisture resistance. be able to.
　そして、本実施の形態では、固体電解質１と陽極２ａ及び陰極２ｂとの間に特定元素含有物質層３ａ、３ｂをそれぞれ介在させることにより、充放電を繰り返しても静電容量の低下が抑制されたサイクル特性の良好な固体イオンキャパシタを得ている。 In the present embodiment, the specific element-containing material layers 3a and 3b are respectively interposed between the solid electrolyte 1 and the anode 2a and the cathode 2b, so that a decrease in capacitance is suppressed even when charging and discharging are repeated. A solid ion capacitor with good cycle characteristics is obtained.
　すなわち、〔発明が解決しようとする課題〕の項でも述べたように、固体電解質を単に薄膜化しただけでは、充放電を繰り返すと静電容量の低下が顕著となり、良好なサイクル特性を確保できない。 That is, as described in the section “Problems to be Solved by the Invention”, simply reducing the thickness of the solid electrolyte results in a significant decrease in capacitance when charging and discharging are repeated, and good cycle characteristics cannot be secured. .
　これは、固体電解質１に含有されるイオン伝導性元素が、充放電時に不可逆反応を伴って電極（陽極２ａ及び陰極２ｂ）や電極と固体電解質１との界面に移動する際に不純物を生成し、その結果、充放電を繰り返すと静電容量が低下し、サイクル特性の劣化を招くものと思われる。 This is because impurities are generated when the ion conductive element contained in the solid electrolyte 1 moves to the electrode (the anode 2a and the cathode 2b) or the interface between the electrode and the solid electrolyte 1 with an irreversible reaction during charging and discharging. As a result, it is considered that when charging / discharging is repeated, the capacitance decreases and the cycle characteristics deteriorate.
　そこで、本実施の形態では、固体電解質１と陽極２ａ及び陰極２ｂとの間に、特定元素含有物質層３ａ、３ｂを介在させることにより、固体電解質１に含有されるイオン伝導性元素が充放電時に陽極２ａ及び陰極２ｂ側に移動しても、該イオン伝導性元素が陽極２ａ及び陰極２ｂとの界面で意図しない不可逆的な化学反応に関与するのを極力抑制でき、これにより充放電を繰り返しても静電容量の低下が少ないサイクル特性の良好な固体イオンキャパシタを得ることができる。 Therefore, in the present embodiment, by interposing the specific element-containing material layers 3a and 3b between the solid electrolyte 1 and the anode 2a and the cathode 2b, the ion conductive element contained in the solid electrolyte 1 is charged and discharged. Even if it moves to the anode 2a and the cathode 2b side at times, it is possible to suppress as much as possible that the ion conductive element participates in an unintended irreversible chemical reaction at the interface between the anode 2a and the cathode 2b. However, it is possible to obtain a solid ion capacitor with good cycle characteristics with little decrease in capacitance.
　このような特定元素含有物質層３ａ、３ｂとしては、イオン伝導性元素を含有していれば特に限定されるものではないが、通常は、固体電解質１内のイオン伝導化合物に含有されるイオン伝導性元素と同一の元素を含有した物質、例えば、固体電解質１内のイオン伝導化合物に含有されるイオン伝導性元素がＬｉの場合は、ＬｉやＬｉを含有したＬｉ化合物が好んで使用される。 The specific element-containing material layers 3a and 3b are not particularly limited as long as they contain an ion conductive element. Usually, the ion conduction contained in the ion conductive compound in the solid electrolyte 1 is used. When the material containing the same element as the ionic element, for example, the ion conductive element contained in the ion conductive compound in the solid electrolyte 1 is Li, Li or a Li compound containing Li is preferably used.
　尚、特定元素含有物質層３ａ、３ｂは、固体電解質１と陽極２ａ及び陰極２ｂとの間に存在していればよく、その厚みは特に限定されるものではないが、１０回程度の充放電を繰り返しても、初期値と遜色がない程度の大きな静電容量を維持するためには、５０～１００ｎｍとするのが好ましい。 The specific element-containing material layers 3a and 3b are only required to be present between the solid electrolyte 1 and the anode 2a and cathode 2b, and the thickness thereof is not particularly limited. In order to maintain a large capacitance that is not inferior to the initial value even if the above is repeated, the thickness is preferably 50 to 100 nm.
　陽極２ａ及び負極２ｂに使用される電極材料は、特に限定されるものではないが、弁作用を有さない非弁作用材料、例えばＡｕ、Ｐｔ、Ｐｄ等の貴金属材料、Ｎｉ、Ｃｕ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ等の遷移金属材料を好んで使用することができ、酸化物材料やＳｉＣ等の半導体材料を使用することも可能である。 The electrode material used for the anode 2a and the anode 2b is not particularly limited, but a non-valve action material having no valve action, for example, a noble metal material such as Au, Pt, Pd, Ni, Cu, Cr, Transition metal materials such as Mn, Fe, and Co can be used preferably, and oxide materials and semiconductor materials such as SiC can also be used.
　ただし、Ａｌ、Ｔｉ、Ｔａ、Ｎｂ、或いはこれらの金属を含んだ合金等、弁作用を有する弁作用金属は、固体イオンキャパシタの作製時に陽極２ａ又は負極２ｂと固体電解質１との界面に容易に絶縁層を形成してしまうおそれがあり、静電容量の低下を招くおそれがあることから、好ましくない。 However, a valve action metal having a valve action such as Al, Ti, Ta, Nb, or an alloy containing these metals can be easily applied to the interface between the anode 2a or the anode 2b and the solid electrolyte 1 during the production of the solid ion capacitor. This is not preferable because an insulating layer may be formed and the capacitance may be reduced.
　また、固体電解質１と特定元素含有物質層３ａ、３ｂとの界面が微小凹凸構造を有するように、前記界面を粗面化するのも好ましい。これにより特定元素含有物質層３ａ、３ｂに接合される陽極２ａ及び陰極２ｂの電極面積が増加することから、固体電解質１の薄層化と相俟って静電容量をより一層大きくすることが可能となる。 It is also preferable to roughen the interface so that the interface between the solid electrolyte 1 and the specific element-containing material layers 3a and 3b has a micro uneven structure. As a result, the electrode areas of the anode 2a and the cathode 2b joined to the specific element-containing material layers 3a and 3b are increased, so that the capacitance can be further increased in combination with the thinning of the solid electrolyte 1. It becomes possible.
　尚、固体電解質１は、後述するように焼成処理により形成される焼結体であることから、焼結された段階で表面は或る程度の凹凸構造を有しており、したがって焼結体の表面が微小凹凸を有するように研磨処理を施した後、特定元素含有物質層３ａ、３ｂを形成したり、或いは焼結体を研磨せずに特定元素含有物質層３ａ、３ｂを形成することにより、前記界面を容易に微小凹凸構造とすることができる。また、固体電解質１の両主面に適宜エッチング等を施して微小凹凸構造とすることもできる。 Since the solid electrolyte 1 is a sintered body formed by a firing process as will be described later, the surface has a certain uneven structure at the stage of sintering. After the polishing process is performed so that the surface has minute irregularities, the specific element-containing material layers 3a and 3b are formed, or the specific element-containing material layers 3a and 3b are formed without polishing the sintered body. The interface can be easily made into a micro uneven structure. In addition, the main surface of the solid electrolyte 1 can be appropriately etched to form a micro uneven structure.
　次に、上記固体イオンキャパシタの製造方法を説明する。 Next, a method for manufacturing the solid ion capacitor will be described.
　まず、原材料を所定量秤量し、混合する。例えば、作製するイオン伝導性化合物がＬｉ、Ｔｉ、Ｐ、及びＯを含むナシコン型結晶相とＡｌＰＯ４との混合相である場合は、原材料としてＬｉ２ＣＯ３等のＬｉ化合物、ＡｌＰＯ４やＨ３ＰＯ４等のＰ化合物、更にはＴｉＯ２等のＴｉ化合物を用意し、これら原材料を所定量秤量し、混合して混合物を得る。 First, a predetermined amount of raw materials are weighed and mixed. For example, when the ion conductive compound to be produced is a mixed phase of a Nasicon type crystal phase containing Li, Ti, P and O and AlPO 4 , the raw material is a Li compound such as Li 2 CO 3 , AlPO 4 or H 3 A P compound such as PO 4 and a Ti compound such as TiO 2 are prepared, and a predetermined amount of these raw materials are weighed and mixed to obtain a mixture.
　次に、この混合物を所定の熱処理プロファイルで熱処理し、イオン伝導性化合物を作製する。 Next, this mixture is heat-treated with a predetermined heat-treatment profile to produce an ion conductive compound.
　尚、イオン伝導性化合物中にガラス成分を含ませる場合は、ＳｉＯ２等のＳｉ化合物を含むガラス材料を所定量秤量して前記原材料と共に混合し、加熱・溶融させた後、急冷してガラス化し、その後、前記所定の熱処理プロファイルで熱処理し、イオン伝導性化合物を作製するのが好ましい。 When a glass component is included in the ion conductive compound, a predetermined amount of a glass material containing a Si compound such as SiO 2 is weighed and mixed together with the raw materials, heated and melted, and then rapidly cooled to be vitrified. Then, it is preferable to heat-treat with the predetermined heat treatment profile to produce an ion conductive compound.
　次いで、このイオン伝導性化合物を、湿式で粉砕した後、バインダ、溶剤、可塑剤等を添加して湿式で十分に混合し、スラリーを得る。そしてこのスラリーを乾燥し造粒した後、ペレット形状等にプレス成形し、薄膜の成形体を得る。 Next, the ion conductive compound is pulverized by a wet process, and then a binder, a solvent, a plasticizer, and the like are added and sufficiently mixed by a wet process to obtain a slurry. And after drying and granulating this slurry, it press-molds to a pellet shape etc. and obtains the molded object of a thin film.
　ここで、バインダ、溶剤、可塑剤等は、特に限定されるものではなく、例えば、バインダとしてはポリビニルブチラール樹脂等、溶剤には酢酸ｎ－ブチル等、可塑剤にはフタル酸ジブチル等をそれぞれ使用することができる。 Here, the binder, solvent, plasticizer, etc. are not particularly limited. For example, polyvinyl butyral resin is used as the binder, n-butyl acetate is used as the solvent, and dibutyl phthalate is used as the plasticizer. can do.
　その後、前記成形体を、例えば、焼成温度を４００℃～１２５０℃、焼成時間を３～７０時間に設定して焼成し、これにより薄膜体（例えば、厚みが２００μｍ以下）の固体電解質１を作製する。 Thereafter, the molded body is fired, for example, by setting the firing temperature to 400 ° C. to 1250 ° C. and the firing time to 3 to 70 hours, thereby producing the solid electrolyte 1 having a thin film body (for example, a thickness of 200 μm or less). To do.
　次に、イオン伝導性元素を含有したイオン伝導性物質、例えばＬｉやＬｉ化合物等を用意する。そして、真空蒸着法等の薄膜形成法や電解めっき等のめっき法を使用し、固体電解質１の両主面に特定元素含有物質層を形成する。 Next, an ion conductive material containing an ion conductive element, such as Li or a Li compound, is prepared. Then, a specific element-containing material layer is formed on both main surfaces of the solid electrolyte 1 using a thin film forming method such as a vacuum deposition method or a plating method such as electrolytic plating.
　次いで、電極材料として、好ましくは弁作用を有さない非弁作用材料、例えば、Ａｕ、Ｐｔ、Ｐｄ等の貴金属材料、Ｎｉ、Ｃｕ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ等の遷移金属材料、酸化物材料やＳｉＣ等の半導体材料を用意し、この電極材料を使用し、固体電解質１の両主面に陽極２ａ及び陰極２ｂを作製し、これにより固体イオンキャパシタが作製される。 Next, as the electrode material, preferably a non-valve action material having no valve action, for example, noble metal material such as Au, Pt, Pd, transition metal material such as Ni, Cu, Cr, Mn, Fe, Co, oxide A material, a semiconductor material such as SiC, is prepared, and this electrode material is used to produce the anode 2a and the cathode 2b on both main surfaces of the solid electrolyte 1, thereby producing a solid ion capacitor.
　陽極２ａ及び陰極２ｂの形成方法は、特に限定されるものではなく、例えば、スパッタリング法や真空蒸着法等の薄膜形成法、ペーストを塗布して焼付ける塗布法、電解めっき等のめっき法、溶射法等、任意の方法を使用することができる。 The formation method of the anode 2a and the cathode 2b is not particularly limited. For example, a thin film formation method such as a sputtering method or a vacuum evaporation method, a coating method in which a paste is applied and baked, a plating method such as electrolytic plating, or thermal spraying. Any method can be used.
　このように本実施の形態では、固体電解質１が、薄膜体で形成されると共に、イオン伝導性化合物が含有され、かつイオン伝導性元素を含有した特定元素含有物質層３ａ、３ｂが固体電解質１と陽極２ａ及び陰極２ｂとの界面に介在されているので、大きな静電容量を得ることができると共に、良好なサイクル特性を有する固体イオンキャパシタを得ることができる。 As described above, in the present embodiment, the solid electrolyte 1 is formed of a thin film body, the ion conductive compound is contained, and the specific element-containing material layers 3a and 3b containing the ion conductive element are the solid electrolyte 1. Since it is interposed at the interface between the anode 2a and the cathode 2b, a large capacitance can be obtained, and a solid ion capacitor having good cycle characteristics can be obtained.
　尚、本発明は上記実施の形態に限定されるものではなく、要旨を逸脱しない範囲で変形可能である。上記実施の形態では、単板形状の固体イオンキャパシタを例示したが、積層セラミックコンデンサに類似した積層構造とするのも好ましい。すなわち、薄膜体からなる固体電解質の一方の主面に特定元素含有物質層及び陽極が形成され、他方の主面に特定元素含有物質層及び陰極が形成されるように、固体電解質、特定元素含有物質層、陽極、及び陰極からなるキャパシタ素体を多数積層してキャパシタ本体部を形成し、該キャパシタ本体部の両端部に外部電極を形成することにより、積層セラミックコンデンサに類似した積層構造となり、小型でより大きな静電容量を有し、かつ良好なサイクル特性を有する固体イオンキャパシタを容易に実現することができる。 In addition, this invention is not limited to the said embodiment, It can deform | transform in the range which does not deviate from a summary. In the above embodiment, a single plate-shaped solid ion capacitor is illustrated, but it is also preferable to have a multilayer structure similar to a multilayer ceramic capacitor. That is, the solid electrolyte and the specific element are contained so that the specific element-containing material layer and the anode are formed on one main surface of the thin-film solid electrolyte, and the specific element-containing material layer and the cathode are formed on the other main surface. A capacitor body composed of a material layer, an anode, and a cathode is laminated to form a capacitor body, and external electrodes are formed on both ends of the capacitor body to form a multilayer structure similar to a multilayer ceramic capacitor. A small solid ion capacitor having a larger capacitance and good cycle characteristics can be easily realized.
　次に、本発明の実施例を具体的に説明する。 Next, specific examples of the present invention will be described.
〔試料の作製〕
〔試料番号２～４〕
　原材料としてＨ３ＰＯ４、Ｌｉ２ＣＯ３、Ａｌ（ＰＯ３）３、ＳｉＯ２、及びＴｉＯ２を用意し、これら原材料を所定量秤量して混合し、混合物を得た。 [Sample preparation]
[Sample Nos. 2 to 4]
H 3 PO 4 , Li 2 CO 3 , Al (PO 3 ) 3 , SiO 2 , and TiO 2 were prepared as raw materials, and a predetermined amount of these raw materials were weighed and mixed to obtain a mixture.
　次いで、この混合物を溶融窯に投入し、１５００℃の温度で３時間加熱して溶融させ、溶融した混合物を溶融窯の底に設けられたスリット状穴から３００℃の温度で成形型に流し出して急冷し、ガラス状の成形体を得た。 Next, this mixture is put into a melting kiln, heated and melted at a temperature of 1500 ° C. for 3 hours, and the melted mixture is poured out from a slit-like hole provided at the bottom of the melting kiln to a mold at a temperature of 300 ° C. And rapidly cooled to obtain a glassy molded body.
　次いで、このガラス状の成形体を所定の熱処理プロファイルで熱処理し、Ｌｉイオン伝導性化合物を得た。具体的には、熱処理炉を３００℃／ｈの昇温速度で室温から６００℃まで上昇させた後、１００℃／ｈの昇温速度で９５０℃まで上昇させ、その後、熱処理温度を９５０℃に設定して１０時間保持し、その後室温まで徐冷し、これにより結晶化されたＬｉイオン伝導性化合物を得た。 Next, this glassy molded body was heat-treated with a predetermined heat treatment profile to obtain a Li ion conductive compound. Specifically, the temperature of the heat treatment furnace is increased from room temperature to 600 ° C. at a temperature increase rate of 300 ° C./h, then increased to 950 ° C. at a temperature increase rate of 100 ° C./h, and then the heat treatment temperature is increased to 950 ° C. It was set and held for 10 hours, and then gradually cooled to room temperature, whereby a crystallized Li ion conductive compound was obtained.
　このＬｉイオン伝導性化合物についてＸ線回折装置を使用してＸ線回折スペクトルを測定したところ、ＬｉＴｉ２（ＰＯ４）３のナシコン型結晶とＡｌＰＯ４（ベルリナイト）型結晶の混合相であることが確認された。 When this X-ray diffraction spectrum of this Li ion conductive compound was measured using an X-ray diffractometer, it was found to be a mixed phase of LiTi 2 (PO 4 ) 3 NASICON type crystals and AlPO 4 (Berlinite) type crystals. confirmed.
　そして、このＬｉイオン伝導性化合物の成分組成をＩＣＰ発光分析装置（サーモフィッシャーサイエンティフィック社製ＩＣＡＰ６３００）を使用して測定したところ、組成はＬｉ1.21Ａｌ0.64Ｔｉ1.53Ｓｉ0.16Ｐ2.82Ｏ12であることが確認された。 Then, when the component composition of the Li-ion conductive compound was measured using an ICP emission spectrometer (Thermo Fisher Scientific Inc. ICAP6300), the composition is a Li 1.21 Al 0.64 Ti 1.53 Si 0.16 P 2.82 O 12 It was confirmed.
　次に、このＬｉイオン伝導性化合物を、湿式で粉砕した後、バインダとしてのポリビニルブチラール樹脂、溶剤としての酢酸ｎ－ブチル、及び可塑剤としてのフタル酸ジブチルを添加して湿式で十分に混合し、スラリーを得た。そしてこのスラリーを乾燥し造粒した後、プレス成形し、成形体を作製した。 Next, after this Li ion conductive compound is pulverized wet, polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer are added and thoroughly mixed in a wet manner. A slurry was obtained. And after drying and granulating this slurry, it press-molded and produced the molded object.
　その後、前記成形体を、８００℃の焼成温度で１２時間焼成し、焼結体を得た。次いで、この焼結体を厚みが１６０μｍとなるようにダイヤモンドカッターで切断し、機械的な研磨によって表面を鏡面仕上げし、これにより固体電解質を得た。 Thereafter, the molded body was fired at a firing temperature of 800 ° C. for 12 hours to obtain a sintered body. Next, this sintered body was cut with a diamond cutter so as to have a thickness of 160 μm, and the surface was mirror-finished by mechanical polishing, thereby obtaining a solid electrolyte.
　次に、真空蒸着法を使用し、固体電解質の表面に金属Ｌｉを蒸着し、厚みが１０～１００ｎｍの金属Ｌｉ層（特定元素含有物質層）を形成した。 Next, using a vacuum deposition method, metal Li was deposited on the surface of the solid electrolyte to form a metal Li layer (specific element-containing material layer) having a thickness of 10 to 100 nm.
　次いで、陽極材料及び陰極材料としてＰｔを用意し、真空蒸着法を使用し、金属Ｌｉ層の表面にＰｔを蒸着し、Ｐｔからなる厚みが２００ｎｍの陽極及び陰極をそれぞれ形成し、試料番号２～４の試料を得た。尚、陽極及び陰極の電極表面積は、それぞれ０．２５ｃｍ２であった。 Next, Pt was prepared as an anode material and a cathode material, vacuum deposition was used, and Pt was deposited on the surface of the metal Li layer to form an anode and a cathode each having a thickness of 200 nm. Four samples were obtained. The electrode surface areas of the anode and the cathode were each 0.25 cm 2 .
〔試料番号１〕
　固体電解質の両主面に直接陽極及び陰極を形成した以外は、上記試料番号２～４と同様の方法・手順で、試料番号１の試料を作製した。 [Sample No. 1]
Sample No. 1 was prepared in the same manner and procedure as Sample Nos. 2 to 4, except that the anode and cathode were directly formed on both main surfaces of the solid electrolyte.
〔試料番号５〕
　試料番号２～４と同様の方法・手順で、固体電解質を作製した。 [Sample No. 5]
A solid electrolyte was produced by the same method and procedure as Sample Nos. 2-4.
　次に、陽極材料及び陰極材料としてＰｔを用意し　Ｐｔをターゲットにして固体電解質の両主面にスパッタリング処理を施し、これによりＰｔからなる厚みが２００ｎｍの第１の陽極及び第１の陰極を固体電解質の両主面に形成した。 Next, Pt is prepared as an anode material and a cathode material, Pt is used as a target, and both main surfaces of the solid electrolyte are subjected to sputtering treatment, whereby the first anode and the first cathode made of Pt and having a thickness of 200 nm are made solid. It was formed on both main surfaces of the electrolyte.
　次いで、真空蒸着法を使用し、第１の陽極及び第１の陰極の表面に金属Ｌｉを蒸着し、厚みが５０ｎｍの金属Ｌｉ層を形成した。 Next, using a vacuum vapor deposition method, metal Li was vapor-deposited on the surfaces of the first anode and the first cathode to form a metal Li layer having a thickness of 50 nm.
　そして、再び、Ｐｔをターゲットにして金属Ｌｉ層の表面にスパッタリング処理を施し、これによりＰｔからなる厚みが２００ｎｍの第２の陽極及び第２の陰極を金属Ｌｉ層の表面に形成し、電極中に金属Ｌｉ層が形成された試料番号５の試料を作製した。 Then, again, sputtering is performed on the surface of the metal Li layer using Pt as a target, thereby forming a second anode and a second cathode made of Pt with a thickness of 200 nm on the surface of the metal Li layer. A sample No. 5 having a metal Li layer formed thereon was prepared.
〔試料の評価〕
　試料番号１～５の各試料について、定電圧式の充放電特性評価装置を使用して所定の充放電プロファイルで充放電を行った。 (Sample evaluation)
The samples Nos. 1 to 5 were charged and discharged with a predetermined charge / discharge profile using a constant voltage charge / discharge characteristic evaluation apparatus.
　図３は、本実施例で使用した充放電プロファイルを示す図であり、横軸は時間（分）、縦軸は印加電圧（Ｖ）である。 FIG. 3 is a diagram showing the charge / discharge profile used in this example, where the horizontal axis represents time (minutes) and the vertical axis represents applied voltage (V).
　すなわち、２．５Ｖの定電圧を陽極及び陰極間に印加して３０分間充電し、次いで３０分間放電し、さらに６０分間、陽極及び陰極間を短絡させて放電状態を維持し、その後再度、２．５Ｖの定電圧を陽極及び陰極間に印加して３０分間充電するという充放電サイクルを１０回繰り返した。 That is, a constant voltage of 2.5 V was applied between the anode and the cathode, charged for 30 minutes, then discharged for 30 minutes, and the anode and cathode were short-circuited for another 60 minutes to maintain the discharge state. A charge / discharge cycle of applying a constant voltage of 0.5 V between the anode and the cathode and charging for 30 minutes was repeated 10 times.
　尚、短絡時間を設けたのは、次回サイクルでの静電容量の測定に影響を与えるのを抑止するためである。 Note that the short-circuit time is provided in order to prevent the measurement of the capacitance in the next cycle from being affected.
　そして、充放電時の電流特性から各充放電サイクルにおける比容量を求め、サイクル特性を評価した。 And the specific capacity in each charging / discharging cycle was calculated | required from the electric current characteristic at the time of charging / discharging, and cycling characteristics were evaluated.
　図４は、充放電時の電流特性を示し、横軸は時間（分）、縦軸は電流（a.u）である。 FIG. 4 shows current characteristics during charging and discharging, where the horizontal axis is time (minutes) and the vertical axis is current (a.u).
　比容量は、この電流特性から放電時の電流値を時間で積分し、電荷に換算し、電荷量から静電容量を算出し、さらにこの静電容量を電極表面積で除算して求めた。 The specific capacity was obtained by integrating the current value at the time of discharge with time from this current characteristic, converting it to electric charge, calculating the electrostatic capacity from the amount of electric charge, and further dividing this electrostatic capacity by the electrode surface area.
　次いで、数式（１）に基づき、比容量の初期値Ｃ１及びｎサイクル後の比容量Ｃｎから、ｎサイクル後の比容量変化率ΔＣｎを求め、サイクル特性を評価した。 Next, based on the mathematical formula (1), the specific capacity change rate ΔCn after n cycles was obtained from the initial value C1 of the specific capacity and the specific capacity Cn after n cycles, and the cycle characteristics were evaluated.
　ΔＣｎ＝（Ｃｎ／Ｃ１）×１００...（１）
　ただし、ｎは１～１０である。 ΔCn = (Cn / C1) × 100 (1)
However, n is 1-10.
　表１は、試料番号１～５における金属Ｌｉ層の厚みと位置、比容量の初期値Ｃ１及び１０サイクル後の比容量変化率ΔＣ10を示している。 Table 1 shows the thickness and position of the metallic Li layer, the initial value C1 of the specific capacity, and the specific capacity change rate ΔC 10 after 10 cycles in sample numbers 1 to 5.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　試料番号１～５のいずれの試料においても、固体電解質の厚みが１６０μｍの薄膜体であるので、比容量の初期値Ｃ１は１０１３～１１５８μＦ／ｃｍ２となり、１０００μＦ／ｃｍ２以上の大きな比容量を得ることができた。 In any of the samples Nos. 1 to 5, since the solid electrolyte is a thin film body having a thickness of 160 μm, the initial value C1 of the specific capacity is 1013 to 1158 μF / cm 2 , which is a large specific capacity of 1000 μF / cm 2 or more. I was able to get it.
　しかしながら、試料番号１は、比容量変化率ΔＣ10が７４．６％となり、１０サイクル後には比容量の低下が大きくなることが分かった。これは固体電解質と陽極及び陰極とが界面で直接接触しているため、固体電解質に含有されるＬｉが、充放電時に不可逆反応を伴って電極や電極と固体電解質との界面に移動する際に不純物を生成し、その結果、充放電を繰り返すと静電容量が低下したものと思われる。 However, it was found that Sample No. 1 had a specific capacity change rate ΔC 10 of 74.6%, and the specific capacity decreased greatly after 10 cycles. This is because the solid electrolyte and the anode and cathode are in direct contact with each other at the interface, so that Li contained in the solid electrolyte moves to the electrode or the interface between the electrode and the solid electrolyte with an irreversible reaction during charge and discharge. Impurities are generated, and as a result, repeated charge / discharge is considered to reduce the capacitance.
　また、試料番号５も、比容量変化率ΔＣ10が７２．９％となり、比容量の低下が大きくなった。この場合も固体電解質と陽極及び陰極とが界面で直接接触しているため、試料番号１と同様の理由から充放電を繰り返すと比容量が低下したものと思われる。 In Sample No. 5, the specific capacity change rate ΔC 10 was 72.9%, and the specific capacity decreased greatly. Also in this case, since the solid electrolyte and the anode and the cathode are in direct contact with each other at the interface, it is considered that the specific capacity is reduced when charging and discharging are repeated for the same reason as Sample No. 1.
　これに対し試料番号２～４は、固体電解質と陽極及び陰極との間に金属Ｌｉ層が介在しているので、充放電時にＬｉイオンが電極側に移動しても、該Ｌｉイオンが電極との界面で意図しない不可逆的な化学反応に関与するのを抑制でき、このため比容量変化率ΔＣ10は、９１．７～９７．９％となり、１０サイクル後であっても比容量の低下が小さいことが確認された。 In contrast, in Sample Nos. 2 to 4, since the metal Li layer is interposed between the solid electrolyte and the anode and the cathode, even if Li ions move to the electrode side during charge and discharge, the Li ions are separated from the electrodes. Therefore, the specific capacity change rate ΔC 10 is 91.7 to 97.9%, and the specific capacity decreases even after 10 cycles. It was confirmed to be small.
　また、金属Ｌｉ層を固体電解質と陽極及び陰極との間に介在させることにより、比容量変化率ΔＣ10を抑制できるが、金属Ｌｉ層の厚みが大きくなるに伴い、比容量変化率ΔＣ10をより一層抑制できることも分かった。 Further, the specific capacity change rate ΔC 10 can be suppressed by interposing the metal Li layer between the solid electrolyte and the anode and the cathode. However, as the thickness of the metal Li layer increases, the specific capacity change rate ΔC 10 is reduced. It was also found that it can be further suppressed.
　図５は、試料番号１～５のサイクル特性を示す特性図である。横軸がサイクル回数ｎ、縦軸は比容量の変化率ΔＣｎ（％）を示している。図中、◇印は試料番号１、●印は試料番号２、◆印は試料番号３、〇印は試料番号４、△印は試料番号５の各サイクル特性である。 FIG. 5 is a characteristic diagram showing cycle characteristics of sample numbers 1 to 5. The horizontal axis indicates the number of cycles n, and the vertical axis indicates the change rate ΔCn (%) of the specific capacity. In the figure, the symbol ◇ indicates the cycle characteristics of sample number 1, the symbol ● indicates the sample number 2, symbol ♦ indicates the sample number 3, symbol ◯ indicates the sample number 4, and symbol Δ indicates the cycle characteristic.
　本発明範囲外の試料番号１、５は、第２回目のサイクルで比容量が初期値の９０％程度に低下し、さらに充放電回数が増加するのに伴い、比容量も顕著に低下している。 For sample numbers 1 and 5 outside the scope of the present invention, the specific capacity decreased to about 90% of the initial value in the second cycle, and the specific capacity decreased significantly as the number of charge / discharge cycles increased. Yes.
　これに対し本発明の試料番号２～４は、充放電を繰り返しても比容量の低下が抑制されており、特に金属Ｌｉ層が５０～１００ｎｍの試料番号３、４は、充放電サイクルを繰り返しても、初期値Ｃ１と遜色がない程度に高い比容量を維持できることが分かった。 In contrast, Sample Nos. 2 to 4 of the present invention suppressed the decrease in specific capacity even after repeated charge and discharge, and Sample Nos. 3 and 4 having a metal Li layer of 50 to 100 nm repeated charge / discharge cycles. However, it was found that the specific capacity can be maintained as high as the initial value C1.
　尚、上記実施例は、本発明を具現化した一例に過ぎず、この実施例に限定されるものではない。例えば、固体電解質に含有される元素種についても、例えばＴｉに加え或いはＴｉに代えてＧｅ等の元素を含有させても同様の作用効果を得ることができる。 In addition, the said Example is only an example which actualized this invention, and is not limited to this Example. For example, with respect to the element species contained in the solid electrolyte, for example, the same effect can be obtained even if an element such as Ge is added in addition to Ti or instead of Ti.
　大きな静電容量を有し、かつサイクル特性の良好な固体イオンキャパシタを実現することができる。 A solid ion capacitor having a large capacitance and good cycle characteristics can be realized.
１　固体電解質
２ａ　陽極
２ｂ　陰極
３ａ、３ｂ　特定元素含有物質層 DESCRIPTION OF SYMBOLS 1 Solid electrolyte 2a Anode 2b Cathode 3a, 3b Specific element containing material layer

Claims (8)

  1. 　固体電解質の両主面に電極が形成された固体イオンキャパシタであって、
    　前記固体電解質は、薄膜体からなると共に、イオン伝導性化合物が含有され、
    　かつ、イオン伝導性元素を含有した物質層が前記固体電解質と前記電極との界面に介在されていることを特徴とする固体イオンキャパシタ。     A solid ion capacitor having electrodes formed on both main surfaces of a solid electrolyte,
    The solid electrolyte is made of a thin film body and contains an ion conductive compound,
    A solid ion capacitor comprising a material layer containing an ion conductive element interposed at an interface between the solid electrolyte and the electrode.
  2. 　前記物質層は、厚みが５０～１００ｎｍであることを特徴とする請求項１記載の固体イオンキャパシタ。 The solid ion capacitor according to claim 1, wherein the material layer has a thickness of 50 to 100 nm.
  3. 　前記物質層に含有される前記イオン伝導性元素は、前記イオン伝導性化合物に含有されるイオン伝導性元素と同一であることを特徴とする請求項１又は請求項２記載の固体イオンキャパシタ。 3. The solid ion capacitor according to claim 1, wherein the ion conductive element contained in the material layer is the same as the ion conductive element contained in the ion conductive compound.
  4. 　前記イオン伝導性元素は、Ｌｉであることを特徴とする請求項１乃至請求項３のいずれかに記載の固体イオンキャパシタ。 4. The solid ion capacitor according to claim 1, wherein the ion conductive element is Li.
  5. 　前記イオン伝導性化合物は、ナシコン型結晶相を含有すると共に、少なくともＬｉ、Ａｌ、Ｐ、及びＯを含んでいることを特徴とする請求項１乃至請求項３のいずれかに記載の固体イオンキャパシタ。 4. The solid ion capacitor according to claim 1, wherein the ion conductive compound contains a NASICON crystal phase and contains at least Li, Al, P, and O. 5. .
  6. 　前記イオン伝導性化合物は、ガラス成分を含有していることを特徴とする請求項５記載の固体イオンキャパシタ。 The solid ion capacitor according to claim 5, wherein the ion conductive compound contains a glass component.
  7. 　前記電極は、弁作用を有さない非弁作用材料で形成されていることを特徴とする請求項１乃至請求項６のいずれかに記載の固体イオンキャパシタ。 The solid ion capacitor according to any one of claims 1 to 6, wherein the electrode is formed of a non-valve action material having no valve action.
  8. 　前記非弁作用材料は、貴金属材料、遷移金属材料、酸化物材料、及び半導体材料、又はこれらを組み合わせた材料であることを特徴とする請求項７記載の固体イオンキャパシタ。 The solid ion capacitor according to claim 7, wherein the non-valve action material is a noble metal material, a transition metal material, an oxide material, and a semiconductor material, or a combination thereof.
PCT/JP2014/068216 2013-07-23 2014-07-08 Solid ion capacitor WO2015012100A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006527461A (en) * 2004-05-17 2006-11-30 エルジー・ケム・リミテッド Electrode and manufacturing method thereof
JP2008078119A (en) * 2006-08-25 2008-04-03 Ngk Insulators Ltd Totally solid storage element
JP2014179534A (en) * 2013-03-15 2014-09-25 Ngk Spark Plug Co Ltd Capacitor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006527461A (en) * 2004-05-17 2006-11-30 エルジー・ケム・リミテッド Electrode and manufacturing method thereof
JP2008078119A (en) * 2006-08-25 2008-04-03 Ngk Insulators Ltd Totally solid storage element
JP2014179534A (en) * 2013-03-15 2014-09-25 Ngk Spark Plug Co Ltd Capacitor

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