JP2015095634A - Power storage device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which enables the enhancement of vibration resistance, and the suppression of deformation of an electrode group.SOLUTION: A power storage device comprises: an electrode group including a positive electrode 2 having a positive electrode active material and a positive electrode collector holding the positive electrode active material, a negative electrode 3 having a negative electrode active material and a negative electrode current collector holding the negative electrode active material, and a separator 1 interposed between the positive and negative electrodes; a nonaqueous electrolyte having alkali metal ion conductivity; a case 10 for enclosing the electrode group and the nonaqueous electrolyte; and a third electrode 4 interposed between the electrode group and the case and not involved in power storage. At least the negative electrode 3 includes pre-doped alkali metal. The third electrode 4 includes a first metal porous body having porosity of 50% or more.

Description

  The present invention relates to an electricity storage device including an electrode group in which at least a negative electrode is pre-doped with an alkali metal.

  Amid the close-up of environmental issues, systems for converting clean energy such as sunlight and wind power into electric power and storing it as electric energy are being actively developed. As such an electricity storage device, a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery (LIB) or an electric double layer capacitor (EDLC) is known. However, the lithium ion secondary battery has a limit in the ability to charge and discharge high capacity power in a short time, and the electric double layer capacitor has a limit in the amount of electricity that can be stored. Therefore, in recent years, lithium ion capacitors have attracted attention as large-capacity electricity storage devices that have the advantages of lithium ion secondary batteries and electric double layer capacitors.

  In order to fully exhibit the performance of the lithium ion capacitor, it is necessary to pre-dope lithium at least one of the positive electrode and the negative electrode. For example, when activated carbon is used as the positive electrode active material and hard carbon is used as the negative electrode active material, the positive electrode and the negative electrode originally do not contain lithium. Therefore, unless lithium is replenished, the ionic species responsible for charge transfer is insufficient. Further, in order to obtain a high voltage lithium ion capacitor, it is desired to pre-dope lithium into the negative electrode in advance to lower the negative electrode potential. Also in the field of non-aqueous electrolyte batteries, it has been proposed to pre-dope lithium into the positive electrode or the negative electrode in order to obtain a high-capacity battery.

  Therefore, in the field of lithium ion capacitors and LIBs, a third electrode to which lithium metal is attached is prepared, the third electrode and the negative electrode are electrically connected, and the negative electrode is electrochemically pre-doped with lithium. (Patent Document 1 etc.).

JP 2007-299698 A

  If the lithium metal adhering to the third electrode remains after pre-doping, the safety of the electricity storage device tends to decrease. Therefore, in Patent Document 1, the third electrode is removed after pre-doping. Further, the third electrode does not contribute to an increase in the capacity of the electricity storage device. Accordingly, the presence of the third electrode reduces the space for arranging the electrode group, which may cause a reduction in capacity. Therefore, removing the third electrode is advantageous in terms of increasing the capacity.

  However, by removing the third electrode, the electrode group can easily move in the case. Therefore, when vibration is applied, the welded portion between the positive electrode lead piece or the negative electrode lead piece and the external terminal is damaged, or the corners of the electrode group are deformed.

  One aspect of the present invention is a positive electrode having a positive electrode active material and a positive electrode current collector holding the positive electrode active material, a negative electrode having a negative electrode active material and a negative electrode current collector holding the negative electrode active material, and the positive electrode. A separator interposed between the negative electrode, a nonaqueous electrolyte having alkali metal ion conductivity, a case for sealing the electrode group and the nonaqueous electrolyte, and the electrode group and the case A third electrode that does not participate in power storage, at least the negative electrode contains a pre-doped alkali metal, and the third electrode comprises a first metal porous body having a porosity of 50% or more. Including an electricity storage device.

  In another aspect of the present invention, a positive electrode having a positive electrode active material and a positive electrode current collector holding the positive electrode active material, a negative electrode active material, and a negative electrode having a negative electrode current collector holding the negative electrode active material, and A step of preparing an electrode group including a separator interposed between the positive electrode and the negative electrode, a step of preparing a third electrode supporting an alkali metal, and the electrode group and the third electrode. A step of accommodating in the case such that the third electrode is interposed between the group and the case, a step of electrically connecting the negative electrode and the third electrode, and alkali metal ion conduction in the case. Injecting a non-aqueous electrolyte having a property, pre-doping at least the negative electrode with an alkali metal supported on the third electrode, and sealing the case, the third electrode comprising: 50% porosity Comprising a first metal porous body is an upper, a method for manufacturing a power storage device.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage device with high vibration resistance and the deformation | transformation of an electrode group was suppressed can be provided.

It is a longitudinal cross-sectional view explaining the structure of the cell of the lithium ion capacitor which concerns on one Embodiment of this invention.

[Description of Embodiment of the Invention]
First, the contents of the embodiment of the present invention will be listed and described.
A first aspect of the present invention is: (1) a positive electrode having a positive electrode active material and a positive electrode current collector holding the positive electrode active material; and a negative electrode having a negative electrode active material and a negative electrode current collector holding the negative electrode active material A separator interposed between the positive electrode and the negative electrode, a nonaqueous electrolyte having alkali metal ion conductivity, a case for sealing the electrode group and the nonaqueous electrolyte, and the electrode A third electrode interposed between the group and the case and not involved in power storage, at least the negative electrode contains a pre-doped alkali metal, and the third electrode has a porosity of 50% or more. The present invention relates to an electricity storage device including a monometallic porous body.

  Since the third electrode is interposed between the electrode group and the cell case, external vibration is absorbed, and the vibration resistance of the electricity storage device is improved. The pores of the third electrode can contain an alkali metal for pre-doping. In this case, even if the alkali metal is eluted as ions from the third electrode, the thickness of the third electrode is hardly changed. Therefore, even after pre-doping, the electrode group is suppressed from moving in the cell case. The above effect can also be obtained with LIB. In particular, lithium ion capacitors have a smaller volume change of the electrode group accompanying charging / discharging than LIB, and the volume change can be sufficiently absorbed by the elastic third electrode. . Therefore, deformation of the electrode group is suppressed, and the reliability of the electricity storage device is improved.

  (2) It is preferable that the first metal porous body has a three-dimensional network structure. This is because the elasticity of the third electrode is improved.

  (3) It is preferable that at least a part of the alkali metal pre-doped on the negative electrode is an alkali metal carried by the third electrode. Since the change in the thickness of the third electrode is small before and after pre-doping, the electrode group is suppressed from moving in the case even after pre-doping. In this case, it is preferable that the third electrode is electrically connected to the negative electrode.

  (4) The thickness of the third electrode is preferably 50 to 600 μm. This is because the elasticity of the third electrode is improved. In addition, the thickness of the 3rd electrode here is the thickness when it takes out and measures from a case after pre dope.

  (5) The potential of the negative electrode is preferably 0 to 1 V with respect to the redox potential of the alkali metal in the discharge state of the electricity storage device. That is, pre-doping is preferably performed until the potential of the negative electrode is 0 to 1 V with respect to the redox potential of the doped alkali metal. This is because a high-voltage electricity storage device can be obtained.

  Another aspect of the present invention is (6) a positive electrode having a positive electrode active material and a positive electrode current collector holding the positive electrode active material, a negative electrode active material, and a negative electrode having a negative electrode current collector holding the negative electrode active material, And a step of preparing an electrode group including a separator interposed between the positive electrode and the negative electrode, a step of preparing a third electrode supporting an alkali metal, the electrode group and the third electrode, A step of accommodating in the case such that the third electrode is interposed between the electrode group and the case, a step of electrically connecting the negative electrode and the third electrode, and an alkali metal ion in the case Injecting a non-aqueous electrolyte having conductivity, pre-doping at least the negative electrode with an alkali metal supported on the third electrode, and sealing the case, the third electrode comprising: , Porosity is 50% Comprising a first metal porous body is an upper, a method for manufacturing a power storage device.

[Details of the embodiment of the invention]
Embodiments of the present invention will be specifically described below. In addition, this invention is not limited to the following content, but is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included.

[Third electrode]
The third electrode is disposed so as to be interposed between the electrode group and the case. This is to protect the electrode group from vibration and impact. Especially, it is preferable that the 3rd electrode is arrange | positioned so that a negative electrode may be opposed not via a positive electrode. This is because when the third electrode is an alkali metal supply source for pre-doping the negative electrode with an alkali metal, it is easy to pre-dope the negative electrode quickly and uniformly with the alkali metal. Moreover, it is preferable that the 3rd electrode is arrange | positioned so that an electrode group may be opposed through resin-made porous materials.

  The third electrode includes a first metal porous body having a porosity of 50% or more. When the porosity of the first metal porous body is within this range, high elasticity can be exhibited while maintaining necessary strength. Therefore, the third electrode serves as a buffer material inside the case. For example, the shock and vibration applied to the electrode group from the outside are absorbed to prevent the electrode group from being damaged. Note that expanded metal, screen punch, punching metal, lath plate, etc. are limited to processing up to a porosity of 30% in terms of strength and the like. Therefore, the elasticity with respect to the thickness direction is hardly shown. The porosity is a numerical value obtained by converting the ratio of {1- (mass of porous body / true specific gravity of porous body) / (apparent volume of porous body)} to percentage (%). The porosity of the first metal porous body is preferably 80% or more and 98% or less.

  The first metal porous body preferably has a three-dimensional network structure. Here, the three-dimensional network shape refers to, for example, a structure in which rod-like or fibrous metals constituting a porous body are three-dimensionally connected to each other to form a network. For example, a sponge-like structure and a nonwoven fabric-like structure can be mentioned. The porous body may have communication holes that are continuous with each other, or may have independent holes that are independent of each other without communication. When the first metal porous body has such a three-dimensional network structure, higher elasticity can be exhibited. Note that expanded metal, screen punch, punching metal, lath plate and the like are substantially two-dimensional structures and do not have a three-dimensional network structure. Further, the three-dimensional network skeleton preferably has a cavity inside (that is, is hollow).

  The metal that is the material of the first metal porous body is preferably not alloyed with an alkali metal. When using the third electrode as an alkali metal source, especially when using as a lithium source, copper, copper alloy, nickel or nickel alloy, etc., when using as a sodium source, aluminum or aluminum alloy Etc.

  The first metal porous body can be formed, for example, by coating a resin porous body with the metal as described above. The coating with metal can be performed by, for example, plating, vapor phase (evaporation, plasma chemical vapor deposition, sputtering, etc.), metal paste application, or the like. A three-dimensional network skeleton is formed by coating with metal. Of these coating methods, plating is preferred.

  As the plating treatment, a metal layer may be formed on the surface of the porous resin body (including the surface of the internal void), and a known plating treatment method such as an electrolytic plating method or a molten salt plating method can be employed. By the plating process, a three-dimensional network metal porous body corresponding to the shape of the resin porous body is formed. In addition, when performing a plating process by the electrolytic plating method, it is desirable to form a conductive layer prior to electrolytic plating. The conductive layer may be formed on the surface of the resin porous body by electroless plating, vapor deposition, sputtering, or by applying a conductive agent. The resin porous body is immersed in a dispersion containing the conductive agent. May be formed.

  The resin porous body is not particularly limited as long as it has voids, and a resin foam, a resin nonwoven fabric, or the like can be used. Among them, although the resin foam depends on the type of resin and the method for producing the foam, each of the pores formed inside the foam becomes a cellular shape, these are connected in series, and continuous voids are formed. Since it will be in the formed state, it is preferable. As the resin constituting these porous bodies, those capable of making the inside of the skeleton hollow by decomposition or dissolution while maintaining the shape of the metal three-dimensional network skeleton after the metal coating treatment are preferable. For example, thermosetting resins such as thermosetting polyurethane and melamine resin; thermoplastic resins such as olefin resin (polyethylene, polypropylene, etc.) and thermoplastic polyurethane can be exemplified. Among these, it is preferable to use thermosetting polyurethane or the like from the viewpoint of easily forming pores having a more uniform size and shape.

  The resin in the skeleton is desirably decomposed or dissolved and removed by heat treatment or the like. After the heat treatment, components (resin, decomposition product, unreacted monomer, additive contained in the resin, etc.) remaining in the skeleton may be removed by washing or the like. The resin may be removed by performing a heat treatment while appropriately applying a voltage as necessary. Further, this heat treatment may be performed while applying a voltage in a state where the plated porous body is immersed in a molten salt plating bath. Thus, when the resin inside is removed after the metal coating treatment, a cavity is formed inside the skeleton of the porous metal body, and becomes hollow. The first metal porous body thus obtained has a three-dimensional network structure skeleton corresponding to the shape of the resin foam. As a commercially available metal porous body, “Aluminum Celmet” (registered trademark) manufactured by Sumitomo Electric Industries, Ltd. or “Celmet” (registered trademark) of copper or nickel can be used.

  The thickness of the third electrode in a state in which no alkali metal is supported is preferably 50 to 600 μm, more preferably 100 to 600 μm, and further preferably 150 to 300 μm. When the thickness of the third electrode is within this range, the effect as a buffer material can be further improved while suppressing the volume occupation ratio.

  When the third electrode is disposed so as to face the negative electrode, the area of the orthographic image viewed from the normal direction of the main surface of the negative electrode is viewed from the normal direction of the main surface of the third electrode. The area of the orthographic image is preferably 100 to 120%. If the areas of the negative electrode and the third electrode are substantially the same, the third electrode is disposed so as to face almost the entire surface of the negative electrode, so that the alkali metal can be pre-doped into the negative electrode more uniformly.

  When it can be used as a power storage device, the third electrode carries neither a positive electrode active material nor a negative electrode active material, and does not participate in charge / discharge reactions, that is, power storage. However, the third electrode may carry an alkali metal in a state before being used as an electricity storage device. In addition, it may be electrically connected to the negative electrode. Thereby, the role as an alkali metal supply source for pre-doping alkali metal to at least the negative electrode can be given to the third electrode. Almost all of the alkali metal supported on the third electrode is preferably pre-doped on the negative electrode and / or the positive electrode.

  Note that pre-doping means that an alkali metal is occluded in advance in the negative electrode and / or positive electrode before operating the electricity storage device. The alkali metal may be pre-doped in either the positive electrode or the negative electrode, but when the negative electrode active material is a material that does not contain an alkali metal in advance, it is desirable to pre-dope at least the negative electrode. When the electricity storage device is a capacitor, the negative electrode potential is decreased by pre-doping the negative electrode with an alkali metal. For this reason, the voltage of the capacitor increases, and an increase in capacity can be expected.

  When the third electrode is opposed to the negative electrode only through a porous resin material such as a separator, the negative electrode is pre-doped with alkali metal directly from the alkali metal supported on the third electrode. . When the third electrode is opposed to the negative electrode through the resin porous material and the positive electrode, the negative electrode is preferably pre-doped with an alkali metal through the positive electrode.

  As a method of supporting the alkali metal on the third electrode, a method of attaching an alkali metal foil to the surface of the third electrode, a method of inserting (occluding) an alkali metal into the cavity of the first metal porous body, the first metal And a method of forming an alkali metal film on the surface of the skeleton of the porous body by plating or the like. At this time, it is preferable to fill at least a part of the alkali metal in the pores of the first metal porous body. By electrically connecting the third electrode carrying the alkali metal and the negative electrode and injecting the non-aqueous electrolyte, alkali metal ions are eluted into the non-aqueous electrolyte, and the alkali metal is occluded in the negative electrode and / or the positive electrode. The

  For example, when an alkali metal foil is attached to the surface of the third electrode, the alkali metal foil is almost completely dissolved by pre-doping, and a space corresponding to the thickness of the foil is generated. This space allows the electrode group to move within the container and is one of the causes of the electrode group being damaged. Here, when the alkali metal foil is attached to the surface of the third electrode, the alkali metal foil is pressure-bonded to the surface of the third electrode in order to enhance adhesion and prevent the alkali metal foil from peeling off. The third electrode is compressed accordingly. Therefore, even if the alkali metal foil is completely dissolved by pre-doping, the elastic third electrode tries to recover to the original thickness and fills the space where the alkali metal foil was present. The third electrode is accommodated while being pressed by the case. Therefore, even after pre-doping, the third electrode is pressed by the electrode group and the case. Therefore, a space for moving the electrode group does not occur, and the movement of the electrode group is suppressed.

  In addition, when an alloy-based active material having a large volume change is used as the negative electrode active material, the volume change of the negative electrode and thus the entire electrode group becomes large during charge and discharge. Since the elastic third electrode can absorb this volume change, the outer shape of the electricity storage device can be prevented from being deformed. The alloy-based active material will be described later.

  In addition, as an alkali metal ion, it can select suitably from lithium ion, sodium ion, potassium ion, rubidium ion, a cesium ion, etc. according to the kind of electrical storage device.

[Power storage device]
The power storage device is not particularly limited. Examples thereof include capacitors such as lithium ion capacitors and sodium ion capacitors, nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries and sodium ion secondary batteries, and the like.

  The electricity storage device includes, for example, a positive electrode having a positive electrode active material and a positive electrode current collector holding the positive electrode active material, a negative electrode having a negative electrode active material and a negative electrode current collector holding the negative electrode active material, and the positive electrode and the A step of preparing an electrode group including a separator interposed between the negative electrode, a step of preparing a third electrode supporting an alkali metal, the electrode group and the third electrode, the electrode group and the case A step of accommodating in the case such that the third electrode is interposed therebetween, a step of electrically connecting the negative electrode and the third electrode, and a non-aqueous solution having alkali metal ion conductivity in the case It can be manufactured by injecting an electrolyte and pre-doping at least the negative electrode with an alkali metal supported on the third electrode and sealing the case. Note that the case may be sealed before the pre-doping step.

FIG. 1 schematically shows a configuration of a capacitor cell according to an embodiment of the present invention.
Capacitor 100 includes a stacked electrode group, a non-aqueous electrolyte (both not shown), and a rectangular aluminum case 10 for housing them. The case 10 includes a bottomed container body 12 having an upper opening and a lid 13 that closes the upper opening. However, the electrode group is not limited to the laminated type, and can be configured by winding the positive electrode 2 and the negative electrode 3 through the separator 1.

  Between the electrode group and the case 10, a third electrode 4 that is not involved in power storage is accommodated via a porous material (separator 1 in FIG. 1) so as to face the negative electrode 3. The third electrode 4 is connected to the negative electrode 3 by a third electrode lead piece 4 c so as to have the same potential as the negative electrode 3. When the third electrode 4 supports an alkali metal, by pouring the non-aqueous electrolyte, the supported alkali metal is eluted into the non-aqueous electrolyte and moves in the cell toward the negative electrode 3. . Then, alkali metal ions are occluded in each negative electrode 3 (strictly, the negative electrode active material), whereby alkali metal pre-doping proceeds. When pre-doping, a voltage may be applied between the negative electrode and the third electrode.

  An external positive terminal (not shown) that penetrates the sealing plate 13 while being insulated from the case 10 is provided near one side of the lid portion 13, and the case 10 is located at a position near the other side of the sealing plate 13. An external negative electrode terminal 15 that penetrates the sealing plate 13 in a conductive state is provided. In the center of the sealing plate 13, a safety valve 16 is provided for releasing the gas generated inside when the internal pressure of the electronic case 10 rises.

  The stacked electrode group is composed of a plurality of positive electrodes 2, a plurality of negative electrodes 3, and a plurality of separators 1 interposed between them, each having a rectangular sheet shape. In FIG. 1, the separator 1 is formed in a bag shape so as to surround the positive electrode 2, but the form of the separator is not particularly limited. The plurality of positive electrodes 2 and the plurality of negative electrodes 3 are alternately arranged in the stacking direction within the electrode group.

  A positive electrode lead piece 2 c may be formed at one end of each positive electrode 2. The plurality of positive electrodes 2 are connected in parallel by bundling the positive electrode lead pieces 2 c of the plurality of positive electrodes 2 and connecting them to an external positive terminal provided on the lid portion 13 of the case 10. Similarly, a negative electrode lead piece 3 c may be formed at one end of each negative electrode 3. A plurality of negative electrodes 3 are connected in parallel by bundling the negative electrode lead pieces 3 c of the plurality of negative electrodes 3 and connecting them to the external negative terminal 15 provided on the lid portion 13 of the case 10. It is desirable that the bundle of the positive electrode lead pieces 2c and the bundle of the negative electrode lead pieces 3c are arranged on the left and right sides of the one end surface of the electrode group with an interval so as to avoid mutual contact.

  Both the external positive terminal and the external negative terminal 15 are columnar, and at least a portion exposed to the outside has a screw groove. A nut 7 is fitted in the screw groove of each terminal, and the nut 7 is fixed to the lid portion 13 by rotating the nut 7. A flange portion 8 is provided in a portion of each terminal accommodated in the case, and the flange portion 8 is fixed to the inner surface of the lid portion 13 via a washer 9 by the rotation of the nut 7.

Hereinafter, the configuration of the electrode and the like will be described in more detail in the case of a capacitor and a non-aqueous electrolyte secondary battery.
[Capacitor]
Examples of the capacitor include a lithium ion capacitor and a sodium ion capacitor.

[Positive electrode]
The positive electrode includes a positive electrode current collector and a positive electrode active material held by the positive electrode current collector. In addition, a conductive aid, a binder, and the like may be included as optional components.
In the capacitor, the positive electrode active material does not exchange electrons with alkali metal ions, and physically adsorbs and desorbs alkali metal ions (non-Faraday reaction). Therefore, the positive electrode active material is not particularly limited as long as it is a material that physically adsorbs and desorbs anions or alkali metal ions. Among these, a carbon material is preferable. Examples of the carbon material include activated carbon, mesoporous carbon, microporous carbon, and carbon nanotube. The carbon material may be activated or may not be activated. These carbon materials can be used singly or in combination of two or more. Of the carbon materials, activated carbon, microporous carbon, and the like are preferable.

  Examples of the microporous carbon include microporous carbon obtained by heating a metal carbide such as silicon carbide or titanium carbide in an atmosphere containing chlorine gas.

  As activated carbon, the well-known thing used for a lithium ion capacitor can be used, for example. Examples of the raw material of activated carbon include wood; coconut shells; pulp waste liquid; coal or coal-based pitch obtained by thermal decomposition thereof; heavy oil or petroleum-based pitch obtained by thermal decomposition thereof; phenol resin and the like. The carbonized material is generally then activated. Examples of the activation method include a gas activation method and a chemical activation method.

The average particle size of the activated carbon (particle size D50 at 50% cumulative volume of volume particle size distribution, the same shall apply hereinafter) is not particularly limited, but is preferably 20 μm or less, and more preferably 3 to 10 μm. The specific surface area is not particularly limited, but is preferably about 800 to 3000 m ² / g. When the specific surface area is in such a range, it is advantageous for increasing the capacitance of the capacitor, and the internal resistance can be reduced.

  Examples of the conductive auxiliary agent contained in the positive electrode include graphite, carbon black, and carbon fiber. Among these, carbon black is preferable because a sufficient conductive path can be easily formed by using a small amount. Examples of carbon black include acetylene black, ketjen black, and thermal black. The amount of the conductive assistant is preferably 2 to 15 parts by mass, more preferably 3 to 8 parts by mass per 100 parts by mass of the positive electrode active material.

  The binder serves to bind the positive electrode active materials to each other and fix the positive electrode active material to the positive electrode current collector. As the binder, fluororesin, polyamide, polyimide, polyamideimide and the like can be used. As the fluororesin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, or the like can be used. The amount of the binder is preferably 1 to 10 parts by mass and more preferably 3 to 5 parts by mass per 100 parts by mass of the positive electrode active material.

  As the positive electrode current collector, a metal foil, a non-woven fabric made of metal fibers, a porous metal sheet, or the like is used. The metal constituting the positive electrode current collector is preferably aluminum or an aluminum alloy because it is stable at the positive electrode potential, but is not particularly limited. When using an aluminum alloy, it is preferable that metal components (for example, Fe, Si, Ni, Mn, etc.) other than aluminum are 0.5 mass% or less.

  The thickness of the metal foil serving as the positive electrode current collector is, for example, 10 to 50 μm, and the thickness of the metal fiber nonwoven fabric or the metal porous sheet is, for example, 100 to 600 μm. In particular, the positive electrode current collector is a porous metal body having a three-dimensional network structure (second metal porous body) in the same manner as the third electrode in terms of filling property, retention property, and current collecting property of the positive electrode active material. It is preferable that Such a second metal porous body has a hollow skeleton. As the second metal porous body, an aluminum porous body containing aluminum or an aluminum alloy is preferable. As a commercially available aluminum porous body, “Aluminum Celmet” (registered trademark) manufactured by Sumitomo Electric Industries, Ltd. can be used.

  In the positive electrode current collector, the second metal porous body preferably has communication holes, and the porosity is preferably 30% or more and 98% or less, and more preferably 90 to 98%. The second metal porous body can be produced by the same method as the first metal porous body. Moreover, you may form the lead piece for current collection in a positive electrode electrical power collector. The lead piece may be formed integrally with the positive electrode current collector, or a separately formed lead piece may be connected to the positive electrode current collector by welding or the like.

  For example, the positive electrode is applied or filled with a positive electrode mixture slurry containing a positive electrode active material on a positive electrode current collector, and then the dispersion medium contained in the positive electrode mixture slurry is removed. It can be obtained by compressing (or rolling) the current collector holding the. Moreover, as a positive electrode, you may use what is obtained by forming the deposit film of a positive electrode active material on the surface of a positive electrode electrical power collector by vapor phase methods, such as vapor deposition and sputtering. In addition to the positive electrode active material, the positive electrode mixture slurry may contain the above-described binder, conductive additive, and the like.

[Negative electrode]
The negative electrode includes a negative electrode current collector and a negative electrode active material.
In the capacitor, the negative electrode active material exchanges electrons with alkali metal ions (Faraday reaction). Therefore, the negative electrode active material includes a material that occludes and releases (or inserts and desorbs) alkali metal ions. Examples of such materials include carbon materials, lithium titanium oxides (such as spinel type lithium titanium oxides such as lithium titanate), alloy-based active materials, and sodium-containing titanium compounds (such as spinel types such as sodium titanate). Sodium titanium oxide, etc.). Examples of the carbon material include graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), graphite (carbon materials having a graphite-type crystal structure such as artificial graphite and natural graphite), and the like. An alloy-based active material is an active material containing an element that forms an alloy with an alkali metal. Examples thereof include silicon oxide, silicon alloy, tin oxide, and tin alloy. A negative electrode active material may be used individually by 1 type, and may be used in combination of 2 or more type. Of the negative electrode active materials, carbon materials are preferable, and graphite and / or hard carbon are particularly preferable.

  Examples of graphite include natural graphite (such as flake graphite), artificial graphite, and graphitized mesocarbon microspheres. Graphite is a layered structure in which planar six-membered rings of carbon are two-dimensionally connected, and has a hexagonal crystal structure. Alkali metal ions (excluding sodium ions) can easily move between the layers of graphite, and are reversibly inserted and removed from the graphite.

Hard carbon is a carbon material that does not develop a graphite structure even when heated in an inert atmosphere. Fine graphite crystals are arranged in random directions, and nano-order voids are formed between crystal layers. A material having Since the diameter of a typical alkali metal sodium ion is 0.95 angstrom, the size of the void is preferably sufficiently larger than this. The average particle diameter of the hard carbon may be 3 to 20 μm, for example, and 5 to 15 μm enhances the filling property of the negative electrode active material in the negative electrode and suppresses side reactions with the electrolyte (molten salt). Desirable from. The specific surface area of the hard carbon may be, for example, 1 to 10 m ² / g, from the viewpoint of ensuring the acceptability of alkali metal ions and suppressing side reactions with the electrolyte, and is 3 to 8 m ² / g. Preferably there is. Hard carbon may be used individually by 1 type and may be used in combination of multiple types.

  As the negative electrode current collector, a metal foil, a non-woven fabric made of metal fibers, a porous metal sheet, or the like is used. As a metal used as a material, a metal that is not alloyed with an alkali metal can be used. Of these, copper, copper alloy, nickel, nickel alloy, and the like are preferable because they are stable at the negative electrode potential. The copper alloy preferably contains less than 50% by mass of elements other than copper, and the nickel alloy preferably contains less than 50% by mass of elements other than nickel.

  The thickness of the metal foil serving as the negative electrode current collector is, for example, 10 to 50 μm, and the thickness of the metal fiber nonwoven fabric or the metal porous body sheet is, for example, 100 to 600 μm. In particular, the negative electrode current collector is a porous metal body having a three-dimensional network structure (third metal porous body) in the same manner as the third electrode in terms of the filling property, retention property, and current collecting property of the negative electrode active material. It is preferable that Such a third metal porous body has a hollow skeleton. As the third metal porous body, a copper porous body containing copper or a copper alloy is preferable. In addition, as a commercially available copper porous body, "Celmet" (registered trademark) of copper manufactured by Sumitomo Electric Industries, Ltd. can be used.

  In the negative electrode current collector, the third metal porous body preferably has communication holes, and the porosity is preferably 30% or more and 98% or less, and more preferably 90 to 98%. The third metal porous body can be produced by the same method as the first metal porous body. A current collecting lead piece may be formed on the negative electrode current collector. The lead piece may be formed integrally with the negative electrode current collector, or a separately formed lead piece may be connected to the negative electrode current collector by welding or the like.

  The negative electrode is, for example, coated or filled with a negative electrode mixture slurry containing a negative electrode active material on a negative electrode current collector, and then the dispersion medium contained in the negative electrode mixture slurry is removed, and further, if necessary, the negative electrode active material It can be obtained by compressing (or rolling) the current collector holding the. Moreover, as a negative electrode, you may use what is obtained by forming the deposit film of a negative electrode active material on the surface of a negative electrode collector by vapor phase methods, such as vapor deposition and sputtering. The negative electrode mixture slurry may contain a binder, a conductive auxiliary agent and the like in addition to the negative electrode active material. As a binder and a conductive support agent, it can select suitably from what was illustrated about the positive mix.

  In order to lower the negative electrode potential, the negative electrode active material is preferably doped with an alkali metal in advance. This increases the voltage of the capacitor, which is further advantageous for increasing the capacity of the capacitor. In order to suppress the precipitation of alkali metal, it is desirable that the negative electrode capacity be larger than the positive electrode capacity.

  The potential of the negative electrode after pre-doping is preferably 0 to 1 V with respect to the redox potential of the doped alkali metal. In other words, pre-doping is preferably performed until the potential of the negative electrode becomes 0 to 1 V with respect to the redox potential of the doped alkali metal. By setting the potential of the negative electrode in the discharged state within this range, the voltage of the capacitor can be increased.

  The doping of the alkali metal into the negative electrode can be performed by a known method. The alkali metal doping may be performed when the capacitor is assembled. Here, a third electrode carrying an alkali metal is housed in a case together with a positive electrode, a negative electrode, and a non-aqueous electrolyte, and the assembled capacitor is held in a temperature-controlled room at about 60 ° C. to be carried on the third electrode. The alkali metal ions can be eluted from the alkali metal thus formed, and the negative electrode can be doped.

[Separator]
The separator has ion permeability, is interposed between the positive electrode and the negative electrode, and physically separates them to prevent a short circuit. The separator has a porous structure and allows ions to permeate by holding a nonaqueous electrolyte in the pores. As a material of the separator, for example, polyolefin such as polyethylene and polypropylene; polyester such as polyethylene terephthalate; polyamide; polyimide; cellulose; glass fiber and the like can be used. The average pore diameter of the separator is not particularly limited and is, for example, about 0.01 to 5 μm. The thickness of the separator is preferably 10 μm to 500 μm, more preferably 20 to 50 μm. If the thickness is within this range, an internal short circuit can be effectively prevented, and the volume occupancy of the separator in the electrode group can be kept low, so that a high capacity density can be obtained.

[Porous resin material]
The resin porous material has ion permeability. When the resin porous material is interposed between the negative electrode and the third electrode, they can be physically separated to prevent a short circuit. As the porous material made of resin, for example, the same material as the separator can be used. Also, the average pore diameter can be the same as that of the separator.

  The thickness of the resin porous material is preferably 10 μm to 500 μm, more preferably 20 to 50 μm. Setting the thickness of the resin porous material within this range is effective for uniformly pre-doping the negative electrode with an alkali metal. The porosity of the resin porous material is preferably 20 to 80%. Setting the porosity of the resin porous material within this range is effective for smooth movement of the alkali metal.

[Nonaqueous electrolyte]
The non-aqueous electrolyte has alkali metal ion conductivity. Nonaqueous electrolytes include, for example, electrolytes (organic electrolytes) in which a salt of an alkali metal ion and an anion (alkali metal salt) is dissolved in a nonaqueous solvent (or an organic solvent), as well as ions containing an alkali metal ion and an anion. Liquid or the like is used. The concentration of the alkali metal salt in the nonaqueous electrolyte may be, for example, 0.3 to 3 mol / liter.

The kind of the anion (first anion) constituting the alkali metal salt is not particularly limited. For example, an anion of a fluorine-containing acid [anion of fluorine-containing phosphate such as hexafluorophosphate ion (PF ₆ ⁻ ); Anion of fluorine-containing boric acid such as acid ion (BF ₄ ⁻ )], anion of chlorine-containing acid [perchlorate ion (ClO ₄ ⁻ ), etc.], anion of oxyacid having an oxalate group [bis (oxalato) borate Ions (Oxalatoborate ions such as B (C ₂ O ₄ ) ₂ ⁻ ); Oxalatoborate ions such as tris (oxalato) phosphate ions (P (C ₂ O ₄ ) ₃ ⁻ )], fluoroalkanesulfonic acid anion [trifluoromethanesulfonate ion (CF ₃ SO ₃ ^-), etc.], the levator like bissulfonylamide anion It is. One alkali metal salt may be used alone, or two or more alkali metal salts having different types of first anions may be used in combination.

  In the present specification, the “ionic liquid” is a molten salt (molten salt), and is used to mean a liquid having ionic conductivity. When an ionic liquid is used for the nonaqueous electrolyte, the content of the ionic liquid in the nonaqueous electrolyte is preferably 80% by mass or more, and more preferably 90% by mass or more. Furthermore, the non-aqueous electrolyte can contain a non-aqueous solvent, an additive and the like in addition to the ionic liquid. On the other hand, when an organic electrolyte is used for the nonaqueous electrolyte, the total amount of the organic solvent and the alkali metal salt in the nonaqueous electrolyte is preferably 80% by mass or more of the nonaqueous electrolyte, and 90% by mass or more. Is more preferable. Further, the non-aqueous electrolyte can contain an ionic liquid, an additive and the like in addition to the organic electrolyte.

  The non-aqueous solvent is not particularly limited, and known non-aqueous solvents used for lithium ion capacitors and sodium ion capacitors can be used. Non-aqueous solvents include, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; cyclic carbonates such as γ-butyrolactone. Etc. can be preferably used. A non-aqueous solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The ionic liquid containing an alkali metal ion may further contain a second cation in addition to the alkali metal ion (first cation). As such a second cation, an inorganic cation other than an alkali metal, for example, a magnesium ion, a calcium ion, an ammonium cation or the like may be used, but an organic cation is preferable. A 2nd cation can be used individually by 1 type or in combination of 2 or more types.

  Examples of the organic cation used as the second cation include cations derived from aliphatic amines, alicyclic amines and aromatic amines (for example, quaternary ammonium cations), as well as cations having nitrogen-containing heterocycles ( That is, examples include nitrogen-containing onium cations such as cations derived from cyclic amines; sulfur-containing onium cations; and phosphorus-containing onium cations.

[Electrode group]
The capacitor is used in a state where the electrode group including the positive electrode and the negative electrode, the third electrode, and the nonaqueous electrolyte are accommodated in a case. The electrode group is formed by laminating or winding a positive electrode and a negative electrode with a separator interposed therebetween. At this time, the third electrode is disposed between the electrode group and the case so as to face the negative electrode through a separator, for example, and is pressed by the electrode group and the case. When electrically connecting a 3rd electrode and a negative electrode, the lead piece for current collection is formed in a 3rd electrode, and it connects with the lead piece of a negative electrode. The connection may be made inside the case or outside the case. Moreover, while using a metal case and making one of a positive electrode and a negative electrode conduct | electrically_connect with a case, a part of case can be utilized as a 1st external terminal. On the other hand, the other of the positive electrode and the negative electrode is connected to the second external terminal led out of the case in a state insulated from the case, using a lead piece or the like.

[Nonaqueous electrolyte secondary battery]
Examples of the non-aqueous electrolyte secondary battery include a lithium ion secondary battery and a sodium ion secondary battery.

[Positive electrode]
The positive electrode includes a positive electrode current collector and a positive electrode active material held by the positive electrode current collector. In addition, a conductive aid, a binder, and the like may be included as optional components.
In the nonaqueous electrolyte secondary battery, the positive electrode active material exchanges electrons with alkali metal ions (Faraday reaction). Therefore, the positive electrode active material is not particularly limited as long as it is a material that electrochemically occludes and releases alkali metal ions. Such materials include metal chalcogen compounds (sulfides, oxides, etc.), alkali metal-containing transition metal oxides (lithium-containing transition metal oxides, sodium-containing transition metal oxides), alkali metal-containing transition metal phosphates. (Such as iron phosphate having an olivine structure). These materials can be used singly or in combination of two or more.
As the conductive auxiliary agent, the binder, and the positive electrode current collector, the same materials as exemplified in the capacitor can be used.

[Negative electrode]
The negative electrode includes a negative electrode current collector and a negative electrode active material. In addition, a conductive aid, a binder, and the like may be included as optional components.
In the nonaqueous electrolyte secondary battery, the negative electrode active material exchanges electrons with alkali metal ions (Faraday reaction). Therefore, the negative electrode active material is not particularly limited as long as it is a material that occludes and releases alkali metal ions. What was illustrated as a negative electrode active material of a capacitor as a negative electrode active material is mentioned, According to the kind of alkali metal ion, it can select suitably. The negative electrode active material is preferably doped with an alkali metal corresponding to irreversible capacity in advance. Thereby, the increase in capacity of the secondary battery can be expected. The alkali metal doping can be performed by the same method as that for the capacitor.

  As the conductive auxiliary agent, the binder and the negative electrode current collector, the same materials as exemplified in the capacitor can be used. Further, the same materials as exemplified in the capacitor can be used for the separator, the porous resin material, and the nonaqueous electrolyte. The electrode group can be manufactured in the same manner as the method exemplified for the capacitor.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, the following Examples do not limit this invention.
Example 1
A lithium ion capacitor was produced according to the following procedure.
(1) Production of positive electrode (a) Production of positive electrode current collector Thermosetting polyurethane foam (porosity: 95 vol%, surface 1 inch (= 2.54 cm) Number of pores (cells) per length: About 50, 100 mm long × 30 mm wide × 1.1 mm thick) were prepared.

By immersing the foam in a conductive suspension containing graphite, carbon black (average particle size D ₅₀ : 0.5 μm), a resin binder, a penetrating agent, and an antifoaming agent, and then drying. A conductive layer was formed on the surface of the foam. The total content of graphite and carbon black in the suspension was 25% by mass.

The foam having the conductive layer formed on the surface was immersed in a molten salt aluminum plating bath, and a direct current having a current density of 3.6 A / dm ² was applied for 90 minutes to form an aluminum layer. The mass of the aluminum layer per apparent area of the foam was 150 g / m ² . The molten salt aluminum plating bath contained 33 mol% 1-ethyl-3-methylimidazolium chloride and 67 mol% aluminum chloride, and the temperature was 40 ° C.

The foam with the aluminum layer formed on the surface was immersed in a lithium chloride-potassium chloride eutectic molten salt at 500 ° C., and a negative potential of −1 V was applied for 30 minutes to decompose the foam. The obtained aluminum porous body was taken out from the molten salt, cooled, washed with water, and dried to obtain a positive electrode current collector. The obtained positive electrode current collector has a three-dimensional network-like porous structure in which the pores communicate with each other, reflecting the pore shape of the foam, has a porosity of 95%, and an average pore diameter of 550 μm. Yes, the BET specific surface area (BET specific surface area) was 350 cm ² / g, and the thickness was 1100 μm. In addition, the three-dimensional network-like aluminum skeleton had inside it a cavity formed by removing the foam. In this way, a positive electrode current collector was obtained.

(B) Production of positive electrode Activated carbon powder (specific surface area 2300 m ² / g, average particle diameter of about 5 μm) as a positive electrode active material, acetylene black as a conductive assistant, PVDF as a binder (N-containing PVDF at a concentration of 12% by mass) Methyl-2-pyrrolidone (NMP) solution) and NMP as a dispersion medium were mixed and stirred in a mixer to prepare a positive electrode mixture slurry. The mass ratio of each component in the slurry was activated carbon: acetylene black: PVDF = 87: 3: 10.

  The obtained positive electrode mixture slurry was filled in the current collector obtained in the step (a) and dried at 100 ° C. for 30 minutes. The dried product was rolled using a pair of rolls to produce a positive electrode having a thickness of 740 μm.

(2) Production of negative electrode (a) Production of negative electrode current collector By using the same method as for the positive electrode, a foam having a conductive layer formed on the surface was immersed in a copper sulfate plating bath as a work piece to obtain a cathode current density of 2A. A Cu layer was formed on the surface by applying a direct current of / dm ² . The mass of the copper layer per apparent area of the foam was 300 g / m ² . The copper sulfate plating bath contained 250 g / L copper sulfate, 50 g / L sulfuric acid, and 30 g / L copper chloride, and the temperature was 30 ° C.

The foam with the Cu layer formed on the surface is heat-treated at 700 ° C. in an air atmosphere to decompose the foam, and then fired in a hydrogen atmosphere to remove the oxide film formed on the surface. As a result, a copper porous body (negative electrode current collector) was obtained. The obtained negative electrode current collector has a three-dimensional network-like porous structure in which pores communicate with each other, reflecting the pore shape of the foam, has a porosity of 97%, and an average pore diameter of 550 μm. Yes, the BET specific surface area was 200 cm ² / g, and the thickness was 1100 μm. In addition, the three-dimensional network copper skeleton had inside it a cavity formed by removing the foam.

(B) Production of negative electrode By mixing artificial graphite powder as a negative electrode active material, acetylene black as a conductive additive, PVDF as a binder, and NMP as a dispersion medium, a negative electrode mixture slurry is prepared. Prepared. The mass ratio of the graphite powder, acetylene black, and PVDF was 90: 5: 5.
The obtained negative electrode mixture slurry was filled in the current collector obtained in the step (a) and dried at 100 ° C. for 30 minutes. The dried product was rolled using a pair of rolls to produce a negative electrode having a thickness of 180 μm.

(3) Production of third electrode The same copper porous body as the negative electrode current collector was compressed to 200 μm with a roller press and cut into a rectangle of size 105 × 105 mm to produce a third electrode. A lithium foil (thickness: 330 μm) was pressure-bonded to one surface of the obtained third electrode. A nickel lead was welded to the other surface of the third electrode.

(4) Preparation of Separator A polyolefin separator having a thickness of 50 μm (average pore diameter 0.1 μm, porosity 70%) was cut into a size of 110 × 110 mm to prepare 22 separators.

(5) Production of Lithium Ion Capacitor The positive electrode obtained in (1) above was cut into a 100 × 100 mm rectangle to prepare 10 positive electrodes. However, a lead piece for current collection was formed at one end of one side of the positive electrode. Further, the negative electrode obtained in the above (2) was cut into a rectangle of size 105 × 105 mm to prepare 11 negative electrodes. However, a current collecting lead piece was formed at one end of one side of the negative electrode.

  Next, the positive electrode, the negative electrode, and the separator were sufficiently dried by heating at 90 ° C. or higher under a reduced pressure of 0.3 Pa. Thereafter, a separator is interposed between the positive electrode and the negative electrode, the positive electrode lead pieces and the negative electrode lead pieces overlap each other, and the bundle of the positive electrode lead pieces and the bundle of the negative electrode lead pieces are arranged at the left and right target positions. Thus, an electrode group was prepared. Then, the same separator was also arranged outside both ends of the electrode group. Further, the third electrode was disposed on the negative electrode separator, and the obtained laminate was accommodated in a rectangular aluminum case (inner dimensions: 110 mm × 110 mm × 10.5 mm).

Next, a nonaqueous electrolyte was injected into the case to impregnate the positive electrode, the negative electrode, and the separator. As the nonaqueous electrolyte, a solution in which LiPF ₆ was dissolved at a concentration of 1.0 mol / L in a mixed solvent of EC and diethyl carbonate (DEC) in a volume ratio of 1: 1 was used. A bundle of positive electrode lead pieces and a bundle of negative electrode lead pieces were combined into one and welded to external terminals of the case. The lead of the third pole was separately pulled out of the case and the case was sealed.

The negative external terminal and the lead wire of the third electrode were connected to the power supply outside the case. The cell in this state was allowed to stand for a predetermined time in a 45 ° C. thermostat so that the temperature of the electrolyte was the same as the temperature of the thermostat. Next, lithium was occluded between the negative electrode and the third electrode at a current of 0.2 mA / cm ² to a potential of 0 V with respect to metallic lithium. Thereafter, 2.6 mAh / cm ² min was discharged with a current of 0.2 mA / cm ² . Lithium was discharged until the potential of the negative electrode was 0.12 V (vs Li / Li ⁺ ) to complete pre-doping, and a lithium ion capacitor A1 was produced. The design capacity of the lithium ion capacitor A1 was about 2100 mAh when charged with 4.2V.
The following evaluation was performed using the obtained lithium ion capacitor. The thickness of the third electrode after pre-doping was 200 μm when it was taken out and measured after all tests, and almost no lithium metal remained. The porosity of the third electrode was 56%.

Example 2
A lithium ion capacitor A2 was produced in the same manner as in Example 1 except that the thickness of the third electrode was 600 μm. The thickness of the third electrode after pre-doping was slightly reduced and was 550 μm. The porosity of the third electrode was 84%.

<< Comparative Example 1 >>
Instead of the third electrode, a lithium foil (thickness: 330 μm, size: 105) is formed on one surface of a punched copper foil (thickness: 20 μm, opening diameter: 50 μm, opening ratio 50%, 105 × 105 mm, porosity 30%). × 105 mm) was pressure-bonded, and a lithium ion capacitor B1 was produced in the same manner as in Example 1 except that a nickel lead was welded to the other surface. In addition, there was no change in the thickness of the punching copper foil after pre-doping.

[Evaluation method]
(1) Deformation of the case Measure the thickness of the capacitor cell before charging and discharging and after repeating charging and discharging in the voltage range of current value 2C, 2.2 to 4.2 V 500 times at a temperature of 60 ° C., The expansion coefficient ((thickness after charging / discharging−thickness before charging / discharging) / thickness before charging / discharging) × 100) was calculated.

(2) Vibration resistance The cell capacity (mAh) after applying a vibration of acceleration 15 m / s ² , maximum speed 0.25 m / s, displacement 5 mm, vibration frequency 100 Hz in the cell thickness direction for 5 hours was measured. The cell capacity is an average value of 10 cells.

  In the capacitors A1 and A2 using the third electrode having a porosity of 50% or more, there was no significant change in the cell capacity before and after applying vibration. This is considered to be because the damage to the electrode group was suppressed as a result of the vibration resistance obtained by the third electrode. In addition, the capacitors A1 and A2 have a very low expansion coefficient and almost no deformation of the case. I couldn't see it. This is considered to be because the volume change of the electrode group during charging / discharging was absorbed by the third electrode.

  The power storage device of the present invention can be applied to various power storage devices because vibration resistance is improved and deformation of the electrode group is suppressed.

1: separator, 2: positive electrode, 2c: positive electrode lead piece, 3: negative electrode, 3c: negative electrode lead piece, 4: third electrode, 4c: third electrode lead piece, 7: nut, 8: flange, 9: washer 10: Case, 12: Container body, 13: Lid, 14: External positive terminal, 15: External negative terminal, 16: Safety valve, 100: Capacitor

Claims (7)

A positive electrode having a positive electrode active material and a positive electrode current collector holding the positive electrode active material;
A negative electrode having a negative electrode active material and a negative electrode current collector holding the negative electrode active material;
An electrode group comprising: a separator interposed between the positive electrode and the negative electrode;
A non-aqueous electrolyte having alkali metal ion conductivity,
A case for sealing the electrode group and the non-aqueous electrolyte; and
A third electrode interposed between the electrode group and the case and not involved in power storage,
At least the negative electrode comprises a pre-doped alkali metal;
The electricity storage device, wherein the third electrode includes a first metal porous body having a porosity of 50% or more.   The electricity storage device according to claim 1, wherein the first metal porous body has a three-dimensional network structure.   The electricity storage device according to claim 1 or 2, wherein at least a part of the alkali metal pre-doped on the negative electrode is an alkali metal carried by the third electrode.   The electrical storage device as described in any one of Claims 1-3 whose thickness of a said 3rd electrode is 50-600 micrometers.   5. The electricity storage device according to claim 1, wherein a potential of the negative electrode is 0 to 1 V with respect to a redox potential of the alkali metal in a discharged state. A positive electrode having a positive electrode active material and a positive electrode current collector holding the positive electrode active material, a negative electrode having a negative electrode active material and a negative electrode current collector holding the negative electrode active material, and interposed between the positive electrode and the negative electrode Preparing an electrode group including a separator to be
Preparing a third electrode carrying an alkali metal;
Storing the electrode group and the third electrode in the case such that the third electrode is interposed between the electrode group and the case;
Electrically connecting the negative electrode and the third electrode;
Injecting a non-aqueous electrolyte having alkali metal ion conductivity into the case, and pre-doping at least the negative electrode with an alkali metal supported on the third electrode;
Sealing the case, and
The method for manufacturing an electricity storage device, wherein the third electrode includes a first metal porous body having a porosity of 50% or more.   The method for manufacturing an electricity storage device according to claim 6, wherein the pre-doping is performed until the potential of the negative electrode becomes 0 to 1 V with respect to the redox potential of the alkali metal.

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