JP2013206821A - Electrode structure and power storage device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode structure ensuring easy extraction of a current even if a plurality of sintered compact electrodes having a thin collector layer are laminated, and high bonding reliability of an extraction part, and to provide a power storage device using the same.SOLUTION: The electrode structure includes an electrode body 26P consisting of a first sintered compact 21P and a second sintered compact 21P' of an active material, and a tub member having a tub bonding part 24Pi located between the first and second sintered compacts and a tub part 24Po led out from the aperture of the electrode body to the outside. The tub bonding part is larger than the aperture of the electrode body.

Description

  The present invention relates to an electrode structure and an electricity storage device using the same.

  Secondary batteries are often used in portable electronic devices such as mobile phones and notebook PCs. As these devices become smaller and lighter, secondary batteries with higher energy density are required. In particular, lithium ion secondary batteries have become widespread because of their high energy density.

  In order to further increase the energy density of lithium ion secondary batteries, attempts have been made to use a sintered body of an active material as an electrode. However, when a sintered body is used as an electrode, Unlike the case where an electrode is formed by forming an active material layer containing a binder or a conductive material, the current collecting material does not contribute to the adhesion between the current collecting material made of metal foil and the sintered body or the capacity of the battery originally. There is a problem that it is difficult to reduce the thickness of the film, and various countermeasures have been proposed.

  For example, in Patent Document 1, in order to improve the adhesion between the current collecting material and the sintered body, a current collecting layer is provided between the first active material layer and the second active material layer, and these are integrated by sintering. It has been proposed that a positive electrode member is formed, and a current collecting member is formed on a side surface of the positive electrode member to extract current.

  Further, Patent Document 2 discloses that a current collecting function is expressed with a thickness of 1 μm or less by forming a current collector on the active material sintered body by sputtering or vapor deposition.

JP 2010-170972 A JP-A-11-365526

  However, in the invention described in Patent Document 1, the difference in firing shrinkage between each active material layer and the current collecting layer at the time of simultaneous firing of each active material layer and the current collecting layer, and the battery is charged and discharged. Due to the stress due to the volume change of the active material when it is repeated, there is a problem that a crack occurs between each active material layer and the current collecting layer, the internal resistance increases and the function as a battery is impaired. It was. Moreover, in order to take out an electric current from a current collection layer, although the current collection member electrically connected with the current collection layer is provided in the side surface of a positive electrode member, the contact area of a current collector and a current collection member is small, There existed a subject that electrical resistance became large or it was easy to disconnect.

  In Patent Document 2, a current collector is formed by sputtering or vapor-depositing a highly conductive metal on an active material sintered body. Regarding a current extraction method when a plurality of sintered body electrodes are stacked, It was not listed.

  The present invention has been made in view of such a problem, and even when a plurality of sintered electrodes having a thin current collecting layer are laminated, an electrode structure in which current can be easily taken out and bonding reliability of the takeout part is high. And it is providing the electrical storage device using the same.

The electrode structure of the present invention includes an electrode body composed of a first sintered body and a second sintered body that are sintered bodies of active materials, and a tab member, and the first sintered body and the second sintered body. The body is disposed such that current collecting layers provided on one main surface of each of the bodies face each other, and on the main surface of at least one of the first sintered body and the second sintered body A recess is provided on the side surface adjacent to the main surface, and the tab member includes a tab portion located outside the electrode body, the first sintered body, and the second sintered body. And a tab joint disposed in the recess and electrically connected to the current collecting layer, wherein the tab joint is the electrode on which the opening is located. When the contour of the tab joint is projected on a plane along the side surface of the main body, the contour of the tab joint is small. Some and also characterized in that, located outside the contour of the opening.

  An electricity storage device of the present invention comprises a pole group in which a plurality of positive electrodes and negative electrodes are alternately stacked via separators, and at least one of the positive electrode and the negative electrode has the electrode structure described above. To do.

  ADVANTAGE OF THE INVENTION According to this invention, even if it laminates | stacks the some sintered compact electrode which has a thin electrical power collection layer, it can take out an electric current easily and can provide an electrode structure with high joining reliability of an extraction part, and an electrical storage device using the same. .

1A is a perspective view schematically showing a stacked power storage device, and FIG. 2B is a cross-sectional view taken along the line AA ′ in the vicinity of a joint portion between a tab assembly portion and a lead in FIG. The electrode structure which is one Embodiment of this invention typically showed (a) perspective view, (b) BB 'sectional drawing of the recessed part vicinity except the tab member of (a), and (c) (a It is CC 'sectional drawing which shows the state which has arrange | positioned the tab member of () to the recessed part. It is the figure which projected the outline of the opening part, and the outline of a tab junction part on xz plane in Fig.2 (a). It is explanatory drawing about the opening part of a recessed part. It is a figure which shows the example of the shape of the recessed part and tab junction part in this invention.

  First, the electricity storage device will be described with reference to FIG. As illustrated in FIG. 1A, the electricity storage device includes a pole group 15 in which a plurality of positive electrodes 11 </ b> P and negative electrodes 11 </ b> N are alternately stacked via separators 12 inside the exterior body 1. The pole group 15 housed inside the exterior body 1 and the external circuit are electrically connected by the terminal electrode 2 exposed from the sealing portion of the exterior body 1.

  The exterior body 1 may be a flexible film that does not allow moisture or gas to pass, which is called a laminate film. Generally, a polyethylene terephthalate (PET) film, an aluminum foil, and a sealing resin layer are laminated in this order. It is formed by. As the laminate film used in the present embodiment, a general aluminum laminate film marketed for foods and batteries can be used, and further, considering the use of the final laminated power storage device, battery shape, and the like. Select the material. Further, a ceramic or glass heat-resistant container provided with connection terminals can be used as the exterior body 1.

As the material of the terminal electrode 2, for example, aluminum can be used for the positive electrode, and copper or nickel can be used for the negative electrode. As for the thickness and width of the terminal electrode 2, in either case of the positive electrode or the negative electrode, take into consideration the capacity of the power storage device, the current value used, etc. That's fine. In addition, when using the thick terminal electrode 2, in order to prevent the airtight defect by the adhesion failure with the exterior body 1 which consists of a terminal electrode 2 and a laminate film, the sealing resin layer of the laminate film which is the exterior body 1 is made thick. Alternatively, a sealing resin may be separately bonded to the terminal electrode 2 in advance.

  FIG. 1B shows the internal structure of an electricity storage device having a configuration in which four pairs of positive electrodes 11P and negative electrodes 11N are stacked with separators 12 interposed therebetween. Note that the number of pairs of the positive electrode 11P and the negative electrode 11N may be 1 to 3, or 5 or more. The electrode group 15 is formed by stacking the positive electrode 11P, the negative electrode 11N, and the separator 12 in this manner. The pole group 15 may include a positive electrode current collector layer 10P and a negative electrode current collector layer 10N. Moreover, the positive electrode current collecting layer 10P and the positive electrode 11P may be collectively referred to as a positive electrode 11P, and the negative electrode current collector layer 10N and the negative electrode 11N may be collectively referred to as a negative electrode 11N. As an electrode located in the outermost layer portion of the stacked electrode group 15, a positive electrode 11P is disposed, and the positive electrode 11P is configured such that the positive electrode 11P is disposed only on one main surface of the positive electrode current collecting layer 10P. . Any electrode other than the positive electrode 11P located in the outermost layer portion of the pole group 15 is one in which the positive electrode 11P is disposed on both main surfaces of the positive electrode current collecting layer 10P, or the negative electrode 11N on both main surfaces of the negative electrode current collecting layer 10N. Are arranged.

  And the pole group 15 contains electrolyte (not shown) in order to express the function as an electrical storage device.

  Each of the current collecting layers is provided with a tab for electrically connecting the lead of the terminal electrode 2. In FIG.1 (b), it has shown about the positive electrode tab 4P provided in the positive electrode current collection layer 10P. The plurality of positive electrode tabs 4P provided on the plurality of positive electrode current collecting layers 10P are bundled together in the positive electrode tab assembly portion 5P. One end of the positive electrode lead 3P is electrically connected to the positive electrode tab assembly portion 5P, and the other end of the positive electrode lead 3P is drawn out of the exterior body 1 through the sealing portion of the exterior body 1 and becomes a positive electrode terminal 2P. ing.

  Next, an electrode structure according to an embodiment of the present invention will be described with reference to FIG. In the present embodiment, the first sintered body 21P and the second sintered body 21P ′ for positive electrode obtained by sintering the positive electrode active material are provided with current collecting layers 10P and 10P ′ on one main surface, respectively. The current collecting layers 10P and 10P ′ are arranged so as to face each other to form the positive electrode body 26P. The main surface of the first sintered body 21P on which the current collecting layer 10P is formed is provided with a recess 27P having an opening on one side surface adjacent to the main surface and having a current collector 28P on the inner wall. The current collector 28P is connected to the current collecting layer 10P.

  As shown in FIG. 2C, the positive electrode tab member 24P includes a positive electrode tab portion (hereinafter also referred to simply as a positive electrode tab) 24Po located outside the positive electrode main body 26P and a concave portion of the first sintered body 21P. 27P has a positive electrode tab joint 24Pi sandwiched between the first sintered body 21P and the second sintered body 21P ′, and the positive electrode tab joint 24Pi is a collection provided on the inner wall of the recess 27P. It is electrically connected to the electric body 28P.

  In the present embodiment, as shown in FIG. 3, a recess 27P is provided on a plane along the side surface of the positive electrode body 26P where the recess 27P opens (the xz plane in FIG. 2A, hereinafter also referred to simply as the xz plane). When the contour (solid line) of the opening of the positive electrode main body 26P to be formed and the contour (broken line) of the positive electrode tab joint 24Pi are projected, at least a part of the contour of the positive electrode tab joint 24Pi is outside the contour of the opening. positioned. As shown in FIG. 4A, the outline of the opening of the positive electrode main body 26P is defined by the surface of the current collector 28P and the current collecting layer 10P ′ in the opening of the positive electrode main body 26P formed by the recess 27P. It refers to the inner periphery of the opening to be formed. Further, as shown in FIG. 4B, when there is a portion where the current collector 28P is not provided on the inner wall of the recess 27P, the current collector 28P and the first sintered body at the opening of the positive electrode body 26P. The inner periphery of the opening formed by 21P and the surfaces of the current collecting layers 10P and 10P ′ may be used.

  Furthermore, both the first sintered body 21P and the second sintered body 21P ′ may be provided with a first concave portion 27P and a second concave portion 27P ′. In that case, the contour of the opening of the positive electrode body 26P and Is an opening formed by the current collector 28P provided on the inner wall of the first recess 27P, the current collector 28P ′ provided on the inner wall of the second recess 27P ′, the current collection layer 10P and the current collection layer 10P ′. The inner circumference of Also in this case, if there are portions where the current collectors 28P, 28P ′ are not provided on the inner walls of the recesses 27P, 27P ′, the current collectors 28P, 28P ′ the current collecting layers 10P, 10P ′, the first firing What is necessary is just to set it as the inner periphery of the opening part formed by the joined body 21P and 2nd sintered compact 21P '.

  As described above, the electrode structure in the present embodiment has been described by taking the positive electrode side as an example. However, this is not limited to the positive electrode side, and the same structure can be applied to the electrode structure on the negative electrode side. Hereinafter, when it is not necessary to distinguish between the positive electrode side and the negative electrode side, it is described without adding P or N to the reference numeral.

  In this way, the tab joint portion 24i of the tab member 24P is disposed in the concave portion 27 of the active material sintered body 21 on which the current collector 28 is formed, and the current collector layer 10 is disposed so as to face each other. In the pole group 15 in which the sintered bodies 21 having the thin current collecting layer 10 are laminated, the current can be easily taken out by the tab portions 24o, and the tab joint portions 24i and the current collectors are collected. Since the contact area with the electric body 28 is large as compared with the case where a current collecting member is provided on the side surface of the electrode 11, an increase in electric resistance can also be suppressed. Further, on the xz plane, at least a part of the outline of the tab joint 24 i projected thereon is positioned outside the outline of the opening of the electrode body 26 formed by the recess 27 in which the tab joint 24 i is disposed. By doing so, the tab member 24 can be made difficult to come off from the electrode body 26. In addition, by applying such an electrode structure to the electrode 11 of the electricity storage device, the stacked structure of the pole group 15 and the connection structure with an external circuit can be simplified, and a highly reliable electricity storage device can be obtained.

  The shape of the tab joint 24i is such that at least a part of the outline of the tab joint 24i projected thereon is formed by the recess 27 in which the tab joint 24i is disposed on the xz plane. Any shape may be used as long as it is located outside the outline of the. In particular, in a cross section parallel to the xz plane, the tab member 24 is more likely to fall out of the electrode body 26 such that the cross section of the tab joint 24i has a portion larger than the cross section of the opening of the electrode body 26. It is preferable because it can be made difficult. As a specific shape of the tab joint 24i, for example, as shown in FIG. 2 (c), in the cross section parallel to the xy plane of FIG. 2 (a), the end of the tab joint extends toward the tip. As shown in FIG. 5, (a) T-shaped, (b) L-shaped, (c) circular end, (e) arrow-shaped, and the like. Note that the contour projected on the xz plane of the tab joint 24 i may protrude in the z-axis direction with respect to the contour of the opening of the electrode body 26, but from the viewpoint of securing the strength of the sintered body 21, x It is preferable to protrude in the axial direction, that is, the direction along the main surface of the sintered body 21.

  Further, the current collecting layer 10 of the first sintered body 21 and the current collecting layer 10 'of the second sintered body 21' are preferably in close contact with each other. When the current collecting layer 10 of the first sintered body 21 and the current collecting layer 10 'of the second sintered body 21' are in close contact with each other, an electric storage device having a low internal resistance and a large capacity is obtained.

The size of the recess 27 is such that the volume of the space formed when the current collecting layer 10 of the first sintered body 21 and the current collecting layer 10 ′ of the second sintered body 21 ′ are in close contact with each other is determined by the tab joint 24i. It is preferable that the volume is storable, that is, the size of the tab joint 24i or more. By setting the concave portion 27 to such a size, a load applied to the electrode body 26 and the tab member 24 can be reduced, and deterioration and breakage thereof can be suppressed. In addition, it is preferable that the shape of the concave portion 27 is a shape that follows the shape of the tab joint portion 24i from the viewpoint of minimizing a space that does not contribute to capacity formation. The tab joint 24i may be in direct contact with the current collector 28, but may be bonded to the current collector 28 with an adhesive containing a conductive filler. Further, a conductive adhesive or a conductive resin may be used as the current collector 28.

  The thickness of the current collecting layer 10 may be 0.1 to 5 μm, for example. With such a thickness, a sufficient current collecting function can be obtained, and the influence on the electrode capacity can be minimized. Such a current collecting layer 10 can be formed by applying a conductive paste or forming a metal layer by sputtering or vapor deposition. In particular, a metal layer formed by sputtering or vapor deposition is preferable as the current collecting layer 10 of the present embodiment because it has a high adhesiveness with a sintered body even if it has a thickness of 1 μm or less and a sufficient current collecting function is obtained.

  For example, a metal foil having a thickness of 5 to 40 μm may be used as the tab member 24. The thickness of the metal foil may be appropriately selected within the range that does not interfere with the production process from the flexibility and strength of the material. The size of the tab joint 24i located inside the electrode body 26 is small enough to ensure the capacity of the power storage device according to the size, capacity, use conditions, etc. of the power storage device, and the reliability of the tab joint 24i. It is sufficient to design appropriately to such an extent that the property can be secured. In addition, the width of the tab portion 24o is large enough not to cause a problem such as heat generation according to the capacity of the power storage device, usage conditions, etc., and does not cause a short circuit due to contact with the tab 4 or the lead 3 of the counter electrode. To design.

  In the electricity storage device of this embodiment, it is sufficient that at least one of the positive electrode 11P and the negative electrode 11N has the electrode structure of the present invention, and the other electrode 11 is a coated electrode, that is, an active material and a binder. A coating film in which a coating liquid containing the coating liquid is applied onto a current collector and dried or heat-treated to be bonded to the current collector may be used as an electrode.

  As the material of the positive electrode current collecting layers 10P and 10P ', a material having corrosion resistance that does not cause a reaction such as dissolution at the potential of the positive electrode may be used. As such a material, for example, a metal material or alloy containing aluminum, tantalum, niobium, titanium, gold, platinum, or the like, or a carbonaceous material such as graphite, hard carbon, or glassy carbon can be used. Among these, aluminum, gold, and platinum are preferable because they are excellent in corrosion resistance and easily available. Aluminum is particularly preferable because it is passivated by forming an oxide film on the surface and excellent in corrosion resistance even at a high potential.

  For the positive electrode tab member 24P and the positive electrode lead 3P whose one end is drawn out of the exterior body 1 and becomes the positive electrode terminal 2P, basically, the metal mentioned as the material of the positive electrode current collecting layers 10P, 10P ′ may be used. Specifically, aluminum is suitably used in terms of cost, flexibility, strength, etc., and titanium and stainless steel can also be used. The widths of the positive electrode lead 3P portion located inside the outer package 1 and the positive electrode terminal 2P portion located outside the outer package 1 may be basically the same, but may be changed as necessary. The thickness of the positive electrode lead 3P is not particularly limited, but for example, about 0.1 mm is appropriate.

  The positive electrode current collecting layers 10P and 10P ', the positive electrode tab member 24P, and the positive electrode lead 3P may basically be made of the same material, but may be made of different materials.

  As the material of the negative electrode current collecting layer 10N, a material that does not cause a side reaction such as alloying with a metal (for example, Li, Na) that is an ionic conductor at the potential of the negative electrode may be used. As such a material, for example, a metal material or alloy including copper, nickel, brass, zinc, aluminum, stainless steel, tungsten, gold, platinum or the like, or a carbonaceous material such as graphite, hard carbon, or glassy carbon is used. Can do. In particular, it is preferable to use copper or nickel from the viewpoint of high conductivity and relatively low cost.

When the electrode structure of the present embodiment is applied to the negative electrode 11N, the negative electrode tab member 24N (not shown), and the negative electrode lead 3N (not shown), one end of which is drawn out of the exterior body 1 and becomes the negative electrode terminal 2N (not shown). For example, the metals mentioned as the material of the negative electrode current collecting layer 10N may be basically used. Specific examples include copper, nickel, and stainless steel, but it is also possible to use a copper-coated nickel or a clad material bonded with a dissimilar metal. The width of the negative electrode lead 3N portion located inside the exterior body 1 and the width of the negative electrode terminal 2N portion located outside the exterior body 1 may be basically the same, but may be changed as necessary. The thickness of the negative electrode lead 3N is not particularly limited, but for example, about 0.1 mm is appropriate.

  The negative electrode current collecting layer 10N, the negative electrode tab member 24N, and the negative electrode lead 3N may be basically made of the same material, but may be made of different materials.

  In order to ensure electrical connection between the current collector 28 and the tab joint 24i, when using a conductive adhesive, for example, gold, silver, nickel, zinc oxide, tin oxide, indium oxide, titanium oxide, and titanium oxide kalim. A mixture comprising a conductive filler such as an acrylic resin, an epoxy resin, a silicon resin, a polyamide resin, a phenol resin, a polyester resin, a polyimide resin, or the like can be used. The thickness of the conductive adhesive is desirably 10 μm or less in order to minimize the electrical resistance due to the conductive adhesive. Further, a conductive adhesive may be used as the current collector 28.

  Next, the configuration of the pole group 15 of the present embodiment will be described using a lithium ion secondary battery as a representative example. The pole group 15 has a structure in which the positive electrode 11P having the positive electrode current collecting layer 10P and the negative electrode 11N having the negative electrode current collecting layer 10N are alternately stacked via the separator 12.

As an active material used for the positive electrode 11P, a transition metal composite oxide containing lithium, for example, lithium cobalt composite oxide, lithium manganese composite oxide, manganese dioxide, lithium nickel composite oxide, lithium nickel cobalt composite oxide, lithium vanadium. Examples include complex oxides. Among these, in particular, lithium cobalt composite oxide has a high electron conductivity and can be a secondary battery excellent in output characteristics. Further, lithium nickel manganese composite oxide (LiNi _x Mn _y O ₄ (x = 0.1 to 0.5, y = 1.5 to 1.9)) has a higher potential than other materials, and an electromotive force. High secondary battery. The positive electrode 11P is preferably used as a sintered body having a high relative density, and the relative density is preferably 85% or more, and more preferably 90% or more.

  Examples of the active material used for the negative electrode 11N include carbonaceous materials such as graphite, hard carbon, and glassy carbon, metal silicon and its alloys, silicon-containing materials such as compounds containing silicon, oxygen, and nitrogen, titanium oxide, and oxidation. Examples include niobium and lithium titanium composite oxide. In particular, the lithium titanium composite oxide can reduce the volume change of the negative electrode 11N during charge and discharge even when used as a sintered body having a relative density of 85% or more, and further 90% or more, and has good cycle characteristics. A secondary battery can be obtained.

Metal silicon and its alloys, compounds containing silicon, oxygen and nitrogen, and the like are preferable from the viewpoint of obtaining a high capacity. Such a silicon-containing material may be used as a coating film or a sintered body containing the particles and carbon. In addition, although the particle | grains containing silicon change at the time of charging / discharging, even when using as a sintered compact, the stress which generate | occur | produced by the volume change exists in a sintered compact by making a porosity into the range of 10 to 60%. Can be absorbed by pores. A sintered body containing a silicon-containing material is prepared by mixing a raw material powder of a silicon-containing material with a carbonaceous material precursor that is carbonized by heat treatment to form a carbonaceous material, and molding and drying it into a desired shape. It is obtained by performing a heat treatment in an atmosphere. As the carbonaceous material precursor, thermosetting resins such as phenol resin, epoxy resin, polyester resin, furan resin, urea resin, melamine resin, alkyd resin, xylene resin, naphthalene, acenaphthylene, phenanthrene, anthracene, triphenylene, pyrene, Examples thereof include organic materials such as pitch mainly composed of condensed polycyclic hydrocarbon compounds such as perylene, pentaphen, and pentacene, derivatives thereof, or mixtures thereof. The carbonaceous material precursor that is carbonized by heat treatment to become a carbonaceous material may further contain particles of carbonaceous material such as graphite and hard carbon described above. In order to form pores, a resin material that disappears during heat treatment and becomes pores may be added as a pore-forming agent.

  The thickness of each of the positive electrode 11P and the negative electrode 11N is preferably 20 μm to 200 μm. Thereby, the absolute amount of the active material necessary for obtaining the battery capacity can be secured, and a secondary battery having good charge / discharge characteristics can be obtained.

  As the separator 12, for example, a polyolefin fibrous nonwoven fabric, a microporous membrane made of polyolefin, or a ceramic porous material can be used. Here, examples of the polyolefin include polyethylene and polypropylene, and a separator generally used for a lithium ion battery is applicable.

As the electrolyte contained in the electrode group 15, any of organic electrolyte solution, polymer solid electrolyte, inorganic solid electrolyte, ionic liquid, and the like can be used. The organic electrolyte is composed of an organic solvent and an electrolyte salt, and an additive for the purpose of forming a film on the electrode surface, preventing overcharge, imparting flame retardancy, or the like may be added as necessary. As the organic solvent, those having a high dielectric constant, low viscosity and low vapor pressure are suitably used. Examples of such materials include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, Examples thereof include a solvent in which one or two or more selected from 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, methylethyl carbonate, dimethyl carbonate, and diethyl carbonate are mixed. Examples of the electrolyte salt include lithium salts such as LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , and LiN (C ₂ F ₅ SO ₂ ) ₂ .

  Further, when a polymer solid electrolyte or an inorganic solid electrolyte is used as the electrolyte, these electrolytes may be disposed in place of the separator 12.

  As described above, the present embodiment has been described in detail by taking a lithium ion battery as an example, but the present invention is not limited to this, and a sodium ion secondary battery, a lead battery, a nickel cadmium battery, a nickel hydrogen battery, an electric battery The present invention can also be applied to various secondary batteries such as double layer capacitors and lithium ion capacitors, capacitors, and other similar power storage devices.

  Next, an example of a method for forming the electrode structure of this embodiment will be described.

  First, the tab member 24 is prepared. As the tab member 24, for example, a metal foil may be processed into a predetermined shape. The predetermined shape is, for example, one end having a shape as shown in FIG. 2 (c) or FIG. 4, and when placed between the first sintered body 21 and the second sintered body 21 ′, The tab joint portion 24i has a width larger than the boundary portion between the tab joint portion 24i and the tab portion 24o at a portion located inside the electrode body 26.

The active material sintered body 21 having the concave portion 27 on the main surface is produced as follows. The raw material powder of the active material and a binder such as butyral are mixed by a known method using a dispersant, water added with a plasticizer, or an organic solvent such as toluene as a solvent, if necessary, to prepare a slurry. The slurry is coated on a base film such as a polyethylene terephthalate (PET) film by a known method and dried to produce a green sheet having a desired thickness. At this time, the slurry may be dried and granulated, and a green sheet may be produced by roll pressing, or may be press-formed into a desired shape. Two of the obtained green sheets are punched into a desired shape, and one of them is formed with a recess 27 at a desired location using means such as an embossing press. At this time, the concave portion 27 has a shape and a dimension capable of accommodating the tab connecting portion 24i after firing and the formation of the current collecting layer 10, and when the electrode main body 26 is formed, the width of the space formed by the concave portion 27 is small. It is important that it is larger than the width of the opening. Then, the degreasing process is performed as needed, and the sintered compact 21 which has the recessed part 27 is obtained by baking. In addition, what is necessary is just to select a calcination temperature suitably according to the sinterability of the active material which is raw material powder. Alternatively, the desired recesses 27 may be formed by directly processing the sintered body 21 without forming the recesses 27 in the green sheet. The relative density and the porosity of the sintered body 21 of the active material can be calculated using techniques such as Archimedes method, mercury intrusion method, and image analysis of a cross-sectional photograph of the sintered body 21.

  For example, a metal layer such as Pt is formed on the main surface of the sintered body 21 by using, for example, a sputtering method or a vapor deposition method to form the current collecting layer 10. In particular, in the vapor deposition method, a metal layer can be uniformly formed on the inner wall of the recessed portion 27 of the sintered body, and the current collecting layer 10 formed on the main surface of the sintered body 21 and the current collector formed on the inner wall of the recessed portion 27. This is preferable in terms of electrical connection with the electric body 28.

  The tab junction 24i of the tab member 24 is arranged in the concave portion 27 of the sintered body 21 on which the current collecting layer 10 is formed, and the current collecting layer 10 of the other sintered body 21 in which the concave portion 27 is not formed is formed. Superimpose the main surfaces. At this time, the current collector 28 in contact with the tab joint 24i may be bonded using, for example, a Pt paste or the like as necessary.

  In addition, when the recessed part 27 is formed in both of the two sintered bodies 21 to constitute the electrode body, the tab connecting part 24i can be accommodated in the space formed by the recessed parts 27 facing each other. What is necessary is just to form.

  The electrode group 15 with the tab 24o thus manufactured may be stacked so that the positive electrodes 11P and the negative electrodes 11N are alternately arranged with the separators 12 interposed therebetween, thereby forming the electrode group 15.

DESCRIPTION OF SYMBOLS 1 ... Exterior body 2 ... Terminal electrode 2P ... Positive electrode terminal 3P ... Positive electrode lead 4P ... Positive electrode tab 5P ... Positive electrode tab assembly part 10P ... Positive electrode current collection layer 10N ··· Negative electrode current collecting layer 11P · · · Positive electrode 11N · · · Negative electrode 12 · · · Separator 15 · · · Electrode group 21P · · · Sintered body for positive electrode 24P · · · Positive electrode tab member 24Pi · · · Positive electrode Tab joint 24Po .. Positive electrode tab 26P... Positive electrode body 27P... Recessed portion of sintered body on positive electrode side 28P... Current collector provided on inner wall of recessed portion on positive electrode side

Claims (8)

An electrode body composed of a first sintered body and a second sintered body, which are sintered bodies of active materials, and a tab member;
The first sintered body and the second sintered body are arranged such that current collecting layers provided on one main surface of the first sintered body and the second sintered body face each other,
The main surface of at least one of the first sintered body and the second sintered body is provided with a recess so as to have an opening on a side surface adjacent to the main surface,
The tab member includes a tab portion located outside the electrode body,
A tab joint located between the first sintered body and the second sintered body, disposed in the recess, and electrically connected to the current collecting layer;
When projecting the outline of the tab joint on the plane along the side surface of the electrode body on which the opening is located, at least a part of the outline of the tab joint is the contour of the opening. An electrode structure characterized by being located outside.   2. The tab joint portion has a portion in which a cross-sectional area in a cross-section in a direction along a side surface of the electrode body in which the opening of the concave portion is located is larger than a cross-sectional area of the opening. The electrode structure described in 1.   3. The electrode structure according to claim 1, wherein a volume of the concave portion is equal to or larger than a volume of the tab joint portion, and the concave portion has a shape along a shape of the tab joint portion.   It comprises a pole group in which a plurality of positive electrodes and negative electrodes are alternately stacked via separators, and at least one of the positive electrode and the negative electrode has the electrode structure according to any one of claims 1 to 3. A power storage device characterized. The positive electrode has the electrode structure according to any one of claims 1 to 3, and the main surface of the first sintered body and the second sintered body of the positive electrode is made of platinum, gold, and aluminum. 5. At least one of them is deposited as the current collecting layer.
The electricity storage device described in 1.   The electric storage device according to claim 4, wherein the tab member joined to the current collecting layer of the positive electrode is made of an aluminum foil.   The negative electrode has the electrode structure according to any one of claims 1 to 3, and at least one of copper and nickel on the main surface of the first sintered body and the second sintered body of the negative electrode. One of these is deposited as said current collection layer, The electrical storage device in any one of the Claims 4 thru | or 6 characterized by the above-mentioned.   The electric storage device according to claim 4, wherein the tab member joined to the current collecting layer of the negative electrode is made of a copper foil or a nickel foil.

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