Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/04—Construction or manufacture in general
  • H01M10/0431—Cells with wound or folded electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/30—Arrangements for facilitating escape of gases
  • H01M50/342—Non-re-sealable arrangements
  • H01M50/3425—Non-re-sealable arrangements in the form of rupturable membranes or weakened parts, e.g. pierced with the aid of a sharp member
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to an energy storage device in which a safety valve is mounted on a container.
• an energy storage device such as a lithium ion secondary battery
• an energy storage device which includes an electrode assembly, a container which houses the electrode assembly, electrode terminals, and an electrolyte such as an electrolyte solution in the container.
• an abnormal state such as overcharge, an impact or sticking occurs in an energy storage device
• the container may be configured so as to release the generated gas.
• patent document 1 describes a nonaqueous electrolyte solution secondary battery which is one example of an energy storage device, that is, a nonaqueous electrolyte secondary battery.
• This nonaqueous electrolyte solution secondary battery includes a bottomed rectangular cylindrical casing, a sealing element for sealing an opening of the casing, an electrode group which forms a flat electrode assembly housed in the casing, and a nonaqueous electrolyte solution which forms an electrolyte filled in the casing.
• the electrode group is formed by winding a strip-like positive electrode, a strip-like negative electrode and a strip-like separator together.
• the strip-like positive electrode includes a plurality of positive electrode collector tabs formed on one side edge in a projecting manner.
• the strip-like negative electrode includes a plurality of negative electrode collector tabs formed on one side edge in a projecting manner.
• the plurality of positive electrode collector tabs positioned in an opposedly facing manner are electrically connected to a positive terminal formed on the sealing element, and the plurality of negative electrode collector tabs positioned in an opposedly facing manner are electrically connected to a negative terminal formed on the sealing element.
• a safety valve is formed on the sealing element by making a portion of the sealing element thin.
• the safety valve when a pressure in the inside of the casing which is hermetically sealed by the casing and the sealing element is increased and goes beyond a predetermined value, the safety valve is broken so that the rupture of the nonaqueous electrolyte solution secondary battery can be prevented.
• Patent Document l JP-A-2011-70916
• an energy storage device such as a lithium ion secondary battery has been requested to satisfy high inputting and high outputting of electric power. Accordingly, when an abnormal state described above occurs in an energy storage device, a large amount of gas is suddenly generated due to the decomposition of an electrolyte.
• the safety valve when the safety valve is released in response to the increase in the pressure inside the casing, there may be a case where, due to a gas flow generated by a gas jetting from the safety valve with high jetting pressure, the electrode group is moved toward the sealing element while deforming positive electrode collector tabs and negative electrode collector tabs, and closes the safety valve.
• the present invention has been made to overcome the
• an object of the present invention is to provide an energy storage device which can prevent an electrode group, that is, an electrode assembly from closing a safety valve when the safety valve is released.
• the present invention is directed to an energy storage device which includes an electrode assembly formed by stacking electrode plates to each other, and a container, wherein a safety valve is formed on a wall portion of the container, and a recessed portion extending in a direction away from the wall portion is formed on an edge portion of the electrode plate of at least one layer disposed adjacently to the wall portion.
• the recessed portion can ensure a space between the electrode assembly and the wall portion. Accordingly, it is possible to prevent the safety valve from being closed by the electrode assembly and hence, the increased pressure can be released in a stable manner.
• At least a portion of the recessed portion may be configured to face the safety valve in an opposed manner.
• the recessed portion can ensure a space at a position where the recessed portion faces the safety valve in an opposed manner and hence, it is possible to more easily prevent the electrode assembly from closing the safety valve.
• the electrode assembly may be configured such that the electrode assembly is formed by winding the electrode plates, and a winding axis of the electrode assembly intersects with the wall portion.
• a plurality of recessed portions may be formed on the electrode plate such that the recessed portions are arranged in a row in a stacking direction of the electrode plate. With such a configuration, spaces formed by the recessed portions overlap with each other in the stacking direction of the electrode plate. Accordingly, the recessed portions increase a space defined between the electrode assembly and the wall portion of the container and hence, it is possible to more easily prevent the electrode assembly from closing the safety valve.
• the electrode plate may have a tab projecting from an edge portion of the electrode plate disposed adjacently to the wall portion at a position different from the recessed portion.
• the recessed portion is formed in a recessed manner in a direction further away from the wall portion of the container from the edge portion of the electrode plate on which the tab is formed. Accordingly, even when the electrode assembly moves toward the wall portion of the container while the tab is deformed, the recessed portion can ensure a space defined between the electrode assembly and the wall portion of the container.
• the energy storage device of the present invention it is possible to prevent the electrode assembly from closing the safety valve when the safety valve is released.
• Fig. 1 is a perspective view schematically showing an external appearance of an energy storage device according to an embodiment of the present invention.
• Fig. 2 is an exploded perspective view of the energy storage device shown in Fig. 1.
• Fig. 3 is a perspective view showing a portion of an electrode assembly shown in Fig. 2 in a developed manner.
• Fig. 4 is an exploded perspective view of a lid member shown in Fig. 2.
• Fig. 5 is a cross- sectional side view of the energy storage device shown in Fig. 1. That is, Fig. 5 is a view showing a cross section of the energy storage device taken along a plane parallel to a long side wall of a container body at the center of short side walls of the container body as viewed in a direction V.
• Fig. 6 is a cross- sectional side view of the energy storage device shown in Fig. 5 taken along a line VI- VI.
• Fig. 7 is an exploded perspective view substantially equal to Fig. 2 which shows a configuration of a modification of the energy storage device according to an embodiment of the present invention.
• Fig. 8 is a perspective view showing a portion of an electrode assembly shown in Fig. 7 in a developed manner.
• Fig. 1 is a perspective view schematically showing an external appearance of the energy storage device 100 according to the embodiment.
• the energy storage device 100 has an outer profile having a flat rectangular parallelepiped shape.
• the energy storage device 100 is a secondary battery capable of charging and
• the energy storage device 100 is formed of a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery.
• the energy storage device 100 is not limited to a nonaqueous electrolyte secondary battery, and may be a secondary battery other than a nonaqueous electrolyte secondary battery, or may be a capacitor.
• the energy storage device 100 includes a container 10 having a flat rectangular parallelepiped shape, an electrode assembly 20 housed in the container 10, a positive electrode terminal 30 and a negative electrode terminal 40.
• Fig. 2 is an exploded perspective view of the energy storage device 100 shown in Fig. 1.
• the container 10 includes a container body 11 having a bottomed angular cylindrical shape, and a lid member 12 having an elongated rectangular plate shape which can close an opening portion 11a of the container body 11.
• the container body 11 has an outer profile having a flat rectangular parallelepiped shape, and includes a bottom wall lib having an elongated rectangular shape, and four side walls 11c, lid, lie and llf each having a rectangular shape which are erected upright from four edges of the bottom wall lib.
• the side walls 11c and lie are positioned so as to face each other in an opposed manner, and each of the side walls 11c and lie forms a long side wall having a large width (hereinafter the side walls 11c and lie being also referred to as "long side walls 11c and lie").
• the side walls lid and llf are positioned so as to face each other in an opposed manner, and each of the side walls lid and llf forms a short side wall having a small width (hereinafter the side walls lid and llf being also referred to as "short side walls lid and llf).
• the opening portion 11a has an elongated rectangular shape which is substantially equal to the shape of the bottom wall lib.
• the positive electrode terminal 30 and the negative electrode terminal 40 are arranged on an outer surface 12a of the lid member 12.
• a safety valve 70 is formed on the lid member 12 at an intermediate position between the positive electrode terminal 30 and the negative electrode terminal 40. The configuration of the safety valve 70 is described later.
• the lid member 12 is one example of a wall portion of the container 10.
• the container body 11 and the lid member 12 can be fixed to each other by a joining method such as welding in a state where a joining portion of the container body 11 and a joining portion of the lid member 12 are fixed to each other while keeping the joint portions in an air-tight state. With such a configuration, a sealed space is formed in the container 10.
• the container body 11 and the lid member 12 may be made of materials which can prevent the deformation of the container body 11 and the lid member 12 and the deterioration of air-tightness of the joining portions of the container body 11 and the lid member 12 when an internal pressure of the container 10 is increased. Although materials for forming the container body 11 and the lid member 12 are not limited, the container body 11 and the lid member 12 may be made of weldable metal such as stainless steel, aluminum or an aluminum alloy, for example.
• a liquid such as an electrolyte solution (a nonaqueous electrolyte solution in this embodiment) is filled in the container 10 as an electrolyte.
• an electrolyte solution a nonaqueous electrolyte solution in this embodiment
• a kind of electrolyte solution to be filled in the container 10 is not particularly limited and various electrolyte solutions can be selected provided that the performance of the energy storage device 100 is not impaired.
• the positive electrode terminal 30 and the negative electrode terminal 40 are physically and electrically connected to, by way of a positive electrode lead plate 51 and a negative electrode lead plate 61, respectively, a positive electrode collector tab group 24 and a negative electrode collector tab group 25 of the electrode assembly 20 which project from the electrode assembly 20 toward the lid member 12.
• the electrode assembly 20 is a power generating element which can store electricity therein.
• the electrode assembly 20 is formed such that a strip-like positive electrode 21, a strip-like negative electrode 22 and a strip-like separator 23 shown in Fig. 3 are stacked to each other, and a stacked body is spirally wound about a winding axis A in a multi-layered manner.
• Fig. 3 is a perspective view showing a portion of the electrode assembly 20 shown in Fig. 2 in a developed manner.
• the electrode assembly 20 has a flat outer profile, and has an elongated circular cross-sectional shape.
• the winding axis A is an imaginary axis indicated by a chain line in Fig.
• the electrode assembly 20 is substantially symmetrical with respect to the winding axis A.
• the winding axis A extends in a direction substantially perpendicular to the lid member 12 which is a direction intersecting with the lid member 12.
• the electrode assembly 20 is disposed such that edges of the positive electrode 21, the negative electrode 22 and the separator 23 extending along a winding direction face the lid member 12 in an opposed manner.
• the electrode assembly 20 where the winding direction is parallel to the direction that the outer surface 12a of the lid member 12 extends as described above is referred to as a lateral-winding-type electrode assembly.
• a plurality of positive electrode collector tabs 21aa shown in Fig. 3 project from the edge of the positive electrode 21 which extends along the winding direction, and the positive electrode collector tab group 24 is formed by binding the plurality of stacked positive electrode collector tabs 21aa.
• a plurality of negative electrode collector tabs 22aa shown in Fig. 3 project in the same direction as the positive electrode collector tabs 21aa from the edge of the negative electrode 22 which extends along the winding direction, and the negative electrode collector tab group 25 is formed by binding the plurality of stacked negative electrode collector tabs 22aa.
• the above-mentioned electrode assembly 20 is housed in the container body 11 in a state where the electrode assembly 20 is suspended from the lid member 12 by way of the positive electrode lead plate 51, the negative electrode lead plate 61, the positive electrode collector tab group 24 and the negative electrode collector tab group 25.
• the direction of the winding axis A of the electrode assembly 20 of the energy storage device 100 is referred to as the Z axis direction.
• the container body 11 and the lid member 12 are disposed in an overlapping manner along the Z axis direction, and long sides of short side walls lid and llf of the container body 11 extend along the Z axis direction.
• the Z axis direction can be defined as the vertical direction of the energy storage device 100.
• the energy storage device 100 is not disposed in a state where the Z axis direction is not defined as a vertical direction and hence, the Z axis direction is not necessarily limited to the vertical direction.
• the width direction of the energy storage device 100 which extends along a direction toward the negative electrode terminal 40 from the positive electrode terminal 30 and is perpendicular to the Z axis is referred to as the X axis direction. Accordingly, the positive electrode lead plate 51 and the negative electrode lead plate 61 are arranged along the X axis direction, and the short side walls lid and llf of the container body 11 positioned on sides opposite to each other are arranged along the X axis direction.
• the direction perpendicular to the X axis direction and to the Z axis direction is referred to as a Y axis direction. Accordingly, the long side walls 11c and lie of the container body 11 positioned on sides opposite to each other are arranged along the Y axis direction, and short sides of the short side walls lid and llf of the container body 11 extend along the Y axis direction. Further, the Y axis direction can be defined as the thickness direction of the container 10.
• the electrode assembly 20 includes one positive electrode 21 having a shape of an elongated strip-like sheet, one negative electrode 22 having a shape of an elongated strip-like sheet, and two separators 23 having a shape of an elongated strip-like sheet in a state where the electrodes and the separators overlap with each other in layers.
• the electrode assembly 20 is formed by spirally winding together the positive electrode 21, the negative electrode 22 and the separators 23 which overlap with each other in layers in the winding direction B about the winding axis A.
• the winding direction B expressed by a counterclockwise direction in Fig. 3 is the rotation direction of the electrode assembly 20 at the time of winding the positive electrode 21, the negative electrode 22 and the
• the positive electrode 21 is formed such that a positive active material layer 21b (indicated by hatching in Fig. 3) is laminated to
• the negative electrode 22 is formed such that a negative active material layer 22b (indicated by hatching in Fig. 3) is laminated to substantially a whole surface of the negative electrode substrate 22a formed of an elongated strip-like metal foil made of metal such as copper or a copper alloy by a method such as coating.
• the separator 23 is formed using a microporous sheet made of a material having an electrically insulating property such as a resin.
• the positive active material layer 21b may be laminated to one of main surfaces formed on both sides of the positive electrode substrate 21a having a large width and positioned opposite to each other or may be laminated to both main surfaces of the positive electrode substrate 21a.
• the negative active material layer 22b may be laminated to one of main surfaces formed on both sides of the negative electrode substrate 22a having a large width and positioned opposite to each other or may be laminated to both main surfaces of the negative electrode substrate 22a.
• the plurality of positive electrode collector tabs 21aa are formed integrally with the positive electrode substrate 21a at intervals in the longitudinal direction of the positive electrode substrate 21a.
• the positive electrode collector tabs 21aa are arranged such that one positive electrode collector tab 21aa is provided for every one turn of the positive electrode substrate 21a about the winding axis A.
• the positive electrode collector tabs 21aa project from the edge 2 lab in the direction of the winding axis A orthogonal to the longitudinal direction of the positive electrode substrate 21a.
• the positive electrode collector tabs 21aa project from the edge 2 lab in the direction opposite to the direction toward the edge 2 lac.
• the positive electrode collector tabs 21aa are formed of exposed portions of the positive electrode substrate 21a, and do not include the positive active material layer 21b.
• the positive active material layer 21b is laminated to a region of the positive electrode substrate 21a except for the positive electrode collector tabs 21aa.
• the edges 2 lab and 2 lac form edges of the positive electrode 21.
• the plurality of negative electrode collector tabs 22aa are integrally formed with the negative electrode substrate 22a at intervals in the longitudinal direction of the negative electrode substrate 22a.
• the edge 22ab of the negative electrode substrate 22a is positioned on the same side as the edge 21ab of the positive electrode substrate 21a when the negative electrode 22 and the positive electrode 21 are made to overlap with each other for winding.
• the negative electrode collector tabs 22aa are arranged such that one negative electrode collector tab 22aa is provided for every one turn of the negative electrode substrate 22a about the winding axis A.
• the negative electrode collector tabs 22aa project from the edge 22ab in the direction of the winding axis A orthogonal to the longitudinal direction of the negative electrode substrate 22a.
• the negative electrode collector tabs 22aa project from the edge 22ab in a direction opposite to a direction toward the edge 22ac.
• Each negative electrode collector tab 22aa is formed of an exposed portion of the negative electrode substrate 22a, and does not include the negative active material layer 22b.
• the negative active material layer 22b is laminated to a region of the negative electrode substrate 22a except for the negative electrode collector tabs 22aa.
• the edges 22ab and 22ac form edges of the negative electrode 22.
• the separator 23 is formed so as to have a width larger than a width of the negative electrode substrate 22a in the direction of the winding axis A.
• Two separators 23 are formed on wide main surfaces on both sides of one negative electrode 22 respectively.
• the negative electrode collector tabs 22aa pass through between two separators 23, and project from the separators 23.
• one positive electrode 21 is disposed on the separator 23 in an overlapping manner such that the positive electrode 21 is positioned inside the separator 23 adjacently disposed inside the negative electrode 22 when the positive electrode 21 is wound.
• the positive electrode 21 is formed so as to have a width smaller than a width of the negative electrode substrate 22a in the direction of the winding axis A such that the whole positive electrode substrate 21a except for the positive electrode collector tabs 21aa is covered by the negative electrode substrate 22a.
• the whole positive electrode substrate 21a except for the positive electrode collector tabs 21aa faces the negative electrode substrate 22a.
• the positive electrode collector tabs 21aa project from the separators 23.
• a notched portion 2 lad having a rectangular shape is formed on the edge 21ab of the positive electrode substrate 21a and a notched portion 22ad having a rectangular shape is formed on the edge 22ab of the negative electrode substrate 22a.
• the notched portion 21ad extends so as to penetrate the positive electrode substrate 21a and the positive active material layer 21b.
• a gap having a rectangular planar shape is formed in the notched portion 2 lad.
• the notched portion 22ad extends so as to penetrate the negative electrode substrate 22a and the negative active material layer 22b.
• a gap having a rectangular planar shape is formed in the notched portion 22ad. Notched portions are not formed on the separators 23.
• the notched portions 2 lad and 22ad are one example of a recessed portion
• the edge 21ab of the positive electrode substrate 21a and the edge 22ab of the negative electrode substrate 22a are one example of an edge portion on which the recessed portions are formed.
• the notched portion 2 lad formed on the positive electrode substrate 21a forms the recessed portion indented from the edge 2 lab toward the edge 21ac disposed on a side opposite to the edge 21ab.
• the notched portion 22ad formed on the negative electrode substrate 22a forms the recessed portion indented from the edge 22ab toward the edge 22ac disposed on a side opposite to the edge 22ab.
• the notched portion 2 lad and the notched portion 22ad have substantially the same shape. However, a size of the notched portion 2 lad formed on the positive electrode substrate 21a is set to be larger than a size of the notched portion 22ad formed on the negative electrode substrate 22a.
• the notched portion 2 lad and the notched portion 22ad overlap with each other in a state where the notched portion 2 lad and the notched portion 22ad are substantially aligned with each other when the positive electrode 21 and the negative electrode 22 are made to overlap with each other. Further, it is desirable that the notched portion 22ad formed on the negative electrode substrate 22a be positioned inside the notched portion 21ad formed on the positive electrode substrate 21a. Provided that a size of the notched portion 21ad formed on the positive electrode substrate 21a is set to be larger than a size of the notched portion 22ad formed on the negative electrode substrate 22a, it is unnecessary to make the notched portion 21ad and the notched portion 22ad have substantially the same shape.
• the notched portion 2 lad and the notched portion 22ad have substantially the same shape in terms of manufacture.
• the notched portions 2 lad and 22ad may be formed by applying notching such as laser cutting or punching using dies to the edges 21ab and 22ab in a process of preparing the strip-like positive electrode 21 and the negative electrode 22 before the positive electrode 21 and the negative electrode 22 are wound.
• the positive electrode collector tabs 21aa and the negative electrode collector tabs 22aa may be formed at the time of forming the notched portions 2 lad and 22ad by notching, at the time of cutting out the strip-like positive electrode 21 and the strip-like negative electrode 22 by cutting a metal foil material having a wide width or the like.
• the notched portions 2 lad and 22ad are formed on a portion of the edge 21ab and a portion of the edge 22ab, respectively, which are disposed between the positive electrode collector tab 21aa and the negative electrode collector tab 22aa.
• the notched portions 2 lad and 22ad are indented from the edges 2 lab and 22ab, respectively, in a direction opposite to a projecting direction of the positive electrode collector tabs 21aa and the negative electrode collector tabs 22aa.
• the edge 2 lab is present between the notched portions 2 lad and 22ad and the positive electrode collector tab 21aa
• the edge 22ab is present between the notched portions 2 lad and 22ad and the negative electrode collector tab 22aa.
• the electrode assembly 20 is formed so as to have a flat elongated circular cross- sectional shape in an XY plane direction which is substantially perpendicular to the direction of the winding axis A.
• a cross- sectional shape of the electrode assembly 20 may be a shape other than an elongated circular shape, and may be a circular shape, an elliptic type, a rectangular shape, or other polygonal shapes.
• the notched portions 21ad and 22ad are formed on the whole positive electrode 21 and the whole negative electrode 22 which are stacked to each other in the Y axis direction, respectively. Further, all notched portions 2 lad and 22ad are substantially aligned in a row along the Y axis direction. Such notched portions 21ad and 22ad form a counterbore portion 27 which is a recessed portion having a rectangular parallelepiped shape. The notched portions 2 lad and 22ad are arranged so as to form the above-mentioned array at the time of working the positive electrode 21 and the negative electrode 22.
• the separators 23 which are disposed at the position of the notched portions 21ad and 22ad are not shown in Fig. 2 and Fig. 3,
• the positive electrode 21, the negative electrode 22 and the separators 23 which are stacked to each other form a wall body extending along the winding direction B.
• the wall body is formed of two flat wall portions 20a and 20b having a large width and a flat shape, and two bent wall portions 20c and 20d bent to a semicircular shape.
• the flat wall portions 20a and 20b are positioned so as to opposedly face each other with the winding axis A interposed
• the flat wall portions 20a and 20b are disposed adjacently to the long side walls 11c and lie of the container body 11, respectively, and extend along the long side walls 11c and lie.
• the bent wall portions 20c and 20d connect both end portions of the flat wall portion 20a and both end portions of the flat wall portion 20b to each other, respectively.
• the bent wall portions 20c and 20d are positioned so as to opposedly face each other with the winding axis A interposed therebetween, and are positioned adjacently to the short side walls lid and llf of the container body 11, respectively.
• edges of the positive electrode 21 and the negative electrode 22 in a stacked state in the direction of the winding axis A form end portions 20e and 20f of the electrode assembly 20.
• the edge 21ab of the positive electrode substrate 21a and the edge 22ab of the negative electrode substrate 22a are arranged so as to form a surface, and thus forming the end portion 20e of the electrode assembly 20.
• the edge 21ac of the positive electrode substrate 21a and the edge 22ac of the negative electrode substrate 22a are arranged so as to form a surface, and thus forming the end portion 20f of the electrode assembly 20.
• the end portion 20e and the end portion 20f form two end surfaces of the electrode assembly 20 in the direction of the winding axis A.
• all positive electrode collector tabs 21aa and all negative electrode collector tabs 22aa are positioned on the flat wall portion 20a and project from the end portion 20e.
• the positive electrode collector tabs 21aa are substantially arranged in a row along the Y axis direction from the flat wall portion 20a to the flat wall portion 20b thus forming the positive electrode collector tab group 24.
• the negative electrode collector tabs 22aa are substantially aligned in a row along the Y axis direction from the flat wall portion 20a to the flat wall portion 20b thus forming the negative electrode collector tab group 25.
• the notched portions 2 lad and 22ad are positioned away from the positive electrode collector tab group 24 and the negative electrode collector tab group 25 at an intermediate position between the positive electrode collector tab group 24 and the negative electrode collector tab group 25, and are indented from the end portion 20e in a direction opposite to the positive electrode collector tab group 24 and the negative electrode collector tab group 25.
• the notched portions 21ad and 22ad are substantially aligned in a row over the flat wall portion 20a and the flat wall portion 20b thus forming the counterbore portion 27 formed of a recessed portion having a rectangular parallelepiped shape which continuously extends over an area from the flat wall portion 20a to the flat wall portion 20b.
• the counterbore portion 27 is indented from the end portion 20e in a direction opposite to the positive electrode collector tab group 24 and the negative electrode collector tab group 25.
• the separators 23 extend in the counterbore portion 27.
• the microporous separator 23 has a large number of pores. That is, the separator 23 allows a gas to pass therethrough.
• the separator 23 may have notched portions which have the same shape as the notched portions 2 lad and 22ad and are formed at positions
• a size of the notched portions formed on the separators 23 is set to be smaller than a size of the notched portions 2 lad and 22ad. It is desirable that the notched portions formed on the separators 23 be positioned inside the notched portions 2 lad and 22ad when the separators 23, the positive electrode 21 and the negative electrode 22 are made to overlap with each other.
• the notched portions formed on the separators 23 may not have the same shape as the notched portions 2 lad and 22ad. However, it is preferable that the notched portions formed on the separators 23 have the same shape as the notched portions 2 lad and 22ad in terms of manufacture. Even in the case where the microporous separators 23 do not have the above-mentioned notched portions which correspond to the counterbore portion 27, a sufficient amount of gas is allowed to pass through the counterbore portion 27.
• the counterbore portion 27 is surrounded by: a flat bottom portion 27a substantially perpendicular to the winding axis A; a side surface portion 27b erected upright from an end portion of the bottom portion 27a on a bent wall portion 20c side toward the end portion 20e! and a side surface portion 27c erected upright from an end portion of the bottom portion 27a on a bent wall portion 20d side toward the end portion 20e.
• the counterbore portion 27 is opened in a direction from the bottom portion 27a to the end portion 20e, in a direction from the winding axis A to the flat wall portion 20a, and in a direction from the winding axis A to the flat wall portion 20b. That is, the counterbore portion 27 is opened at an open end on an end portion 20e side and at open ends on both sides of counterbore portion 27 in directions along which the positive electrode 21 and the negative electrode 22 are stacked to each other.
• Fig. 4 is an exploded perspective view of the lid member 12 shown in Fig. 2.
• the positive electrode terminal 30 includes a terminal body 31, an upper insulating member 32, and a lower insulating member 33.
• the negative electrode terminal 40 includes a terminal body 41, an upper insulating member 42, and a lower insulating member 43.
• the terminal bodies 31 and 41 are made of a material having conductivity such as metal. Rivet portions 31a and 41a having a circular cylindrical shape are formed on the planar-shaped terminal bodies 31 and 41 in a projecting manner, respectively.
• Upper insulating members 32 and 42, and lower insulating members 33 and 43 are plate-like packings made of a material having an electrically insulating property such as a resin. A through hole which allows the rivet portion 31a to pass
• the rivet portion 31a formed on the terminal body 31 and the rivet portion 41a formed on the terminal body 41 are configured to be electrically connected to a positive electrode collector 50 and a negative electrode collector 60 respectively.
• the positive electrode collector 50 and the negative electrode collector 60 are disposed on a side opposite to the terminal bodies 31 and 41 with the lid member 12 interposed therebetween.
• the positive electrode collector 50 is a planar member having conductivity and rigidity.
• the positive electrode collector 50 is made of metal such as aluminum or an aluminum alloy.
• the negative electrode collector 60 is a planar member having conductivity and rigidity.
• the negative electrode collector 60 is made of metal such as copper or a copper alloy. Through holes which allow the rivet portions 31a and 41a to pass therethrough are formed in the positive electrode collector 50 and the negative electrode collector 60, respectively.
• the rivet portion 31a formed on the terminal body 31 of the positive electrode terminal 30 is made to pass through the through hole formed in the upper insulating member 32, the through hole 12b formed in the lid member 12, the through hole formed in the lower insulating member 33, and the through hole formed in the positive electrode collector 50 in this order and, thereafter, these elements are caulked together by the rivet portion 31a.
• the terminal body 31 and the positive electrode collector 50 are mounted on and fixed to the lid member 12 with the upper insulating member 32 interposed between the terminal body 31 and the lid member 12 and with the lower insulating member 33 interposed between the positive electrode collector 50 and the lid member 12.
• the terminal body 31 is physically and electrically connected to the positive electrode collector 50.
• the upper insulating member 32 electrically insulates the terminal body 31 and the lid member 12 from each other
• the lower insulating member 33 electrically insulates the lid member 12 and the positive electrode collector 50 from each other.
• the rivet portion 41a formed on the terminal body 41 of the negative electrode terminal 40 is made to pass through the through hole formed in the upper insulating member 42, the through hole 12c formed in the lid member 12, the through hole formed in the lower insulating member 43, and the through hole formed in the negative electrode collector 60 in this order and, thereafter, these elements are caulked together by the rivet portion 41a.
• the terminal body 41 and the negative electrode collector 60 are mounted on and fixed to the lid member 12 with the upper insulating member 42 interposed between the terminal body 41 and the lid member 12 and with the lower insulating member 43 interposed between the negative electrode collector 60 and the lid member 12.
• the terminal body 41 is physically and electrically connected to the negative electrode collector 60.
• the upper insulating member 42 electrically insulates the terminal body 41 and the lid member 12 from each other
• the lower insulating member 43 electrically insulates the lid member 12 and the negative electrode collector 60 from each other.
• the connecting structure between the terminal body 31 of the positive electrode terminal 30 and the positive electrode collector 50 and the connecting structure between the terminal body 41 of the negative electrode terminal 40 and the negative electrode collector 60 are not limited to riveting.
• the terminal body 31 and the terminal body 41 are connected with the positive electrode collector 50 and the negative electrode collector 60, respectively, in a state where the upper insulating member 32, the lid member 12 and the lower insulating member 33 are interposed between the terminal body 31 and the positive electrode collector 50, and the upper insulating member 42, the lid member 12 and the lower insulating member 43 are interposed between the terminal body 41 and the negative electrode collector 60
• any structure can be adopted as the connecting structure.
• bolts and nuts may be used in place of the rivet portions 31a and 41a.
• the rivet portions 31a and 41a may be welded to the positive electrode collector 50 and the negative electrode collector 60, respectively.
• the positive electrode lead plate 51 and the negative electrode lead plate 61 are formed of a plate member which is bent into a U shape, for example.
• the positive electrode lead plate 51 is made of the same material as the positive electrode collector 50.
• the negative electrode lead plate 61 is made of the same material as the negative electrode collector 60.
• Planar portions of the U-shaped positive electrode lead plate 51 which form two side portions of the positive electrode lead plate 51 and opposedly face each other are joined to the positive electrode collector 50 and the positive electrode collector tab group 24 of the electrode assembly 20, respectively.
• Planar portions of the U-shaped negative electrode lead plate 61 which form two side portions of the negative electrode lead plate 61 and opposedly face each other are joined to the negative electrode collector 60 and the negative electrode collector tab group 25 of the electrode assembly 20, respectively.
• the joining of the positive electrode lead plate 51 and the joining of the negative electrode lead plate 61 may be performed using welding such as ultrasonic welding or resistance welding.
• the terminal body 31 of the positive electrode terminal 30 is physically and electrically connected to the positive electrode 21 of the electrode assembly 20 with the positive electrode collector 50 and the positive electrode lead plate 51 interposed therebetween.
• the terminal body 41 of the negative electrode terminal 40 is physically and electrically connected to the negative electrode 22 of the electrode assembly 20 with the negative electrode collector 60 and the negative electrode lead plate 61 interposed therebetween.
• a safety valve 70 is formed integrally with the lid member 12 by molding.
• the safety valve 70 includes a weakened portion 71 formed by reducing a thickness of a portion of the lid member 12.
• the weakened portion 71 is formed so as to have an elongated circular planar shape when the outer surface 12a of the lid member 12 is viewed in the Z axis direction.
• the weakened portion 71 is broken thus forming an opening which functions as a pressure relief hole. Accordingly, a pressure in the container 10 is released to the outside.
• the weakened portion 71 may be configured such that a groove portion 72 is further formed on the weakened portion 71 by cutting thus facilitating the breaking of the weakened portion 71 at the groove portion 72.
• the groove portion 72 has a planar shape where two grooves extending in different directions are connected to respective ends of one groove, that is, a planar shape where two grooves having a Y shape are connected with each other. With such a configuration, the breaking of the weakened portion 71 is facilitated at intersecting portions of the grooves.
• Fig. 5 is a cross- sectional side view of the energy storage device 100 shown in Fig. 1. That is, Fig. 5 is a view showing a cross section of energy storage device 100 taken along a plane parallel to the long side walls 11c and lie of the container body 11 at the center of the short side walls lid and llf of the container body 11 as viewed in a direction V which is a Y axis direction.
• Fig. 6 is a cross- sectional side view of the energy storage device 100 shown in Fig. 5 taken along a line VI- VI.
• the electrode assembly 20 is mounted on the lid member 12 with the end portion 20e on which the counterbore portion 27 is formed disposed adjacently to the lid member 12 of the container 10.
• the counterbore portion 27 is positioned so as to face the safety valve 70 in an opposed manner.
• a width Bl of the counterbore portion 27 between the side surface portion 27b and the side surface portion 27c is set to be larger than a width B2 of the weakened portion 71 of the safety valve 70.
• a width of the counterbore portion 27 between the open ends that is, a width B3 of the bottom portion 27a of the counterbore portion 27 is set to be larger than a width B4 of the weakened portion 71 of the safety valve 70. Further, the whole weakened portion 71 of the safety valve 70 faces the counterbore portion 27.
• the electrode assembly 20 moves toward the lid member 12 due to a flow of a gas suddenly flown out to the outside through the safety valve 70.
• the counterbore portion 27 ensures a space at a position where the counterbore portion 27 faces the safety valve 70 in an opposed manner so that a space defined between the container 10 and the electrode assembly 20 and the safety valve 70 communicate with each other through the above-mentioned space.
• the porous separator 23 has a large number of pores thus allowing a gas to pass therethrough, that is, the porous separator 23 has permeability.
• a gas in the container 10 can flow out to the outside through the safety valve 70. Further, by adjusting a shape and a size of the counterbore portion 27, also in the case where the counterbore portion 27 is deformed together with the electrode assembly 20 at the time of collision, a sufficient space can be ensured at a position where the counterbore portion 27 faces the safety valve 70 in an opposed manner.
• the counterbore portion 27 which can acquire the above-mentioned advantageous effect be positioned so as to face at least a portion of the weakened portion 71 of the safety valve 70 in an opposed manner.
• the counterbore portion 27 may not be disposed at the position where the counterbore portion 27 faces the weakened portion 71.
• the counterbore portion 27 communicates with the safety valve 70 through a gap formed by the positive electrode collector tab group 24, the negative electrode collector tab group 25 and the separators 23.
• a depth of the counterbore portion 27 from the end portion 20e to the bottom portion 27a which is a depth of the counterbore portion 27 in a direction away from the lid member 12 can be set such that the counterbore portion 27 can acquire the above-mentioned advantageous effect based on rigidity of the electrode assembly 20 against the deformation at the time of collision, a position of the counterbore portion 27 with respect to the safety valve 70, other sizes of the counterbore portion 27, a shape of the counterbore portion 27 or the like.
• a thickness of one collector tab is set to 0.008 mm or more and the number of collector tabs forming a collector tab group is set to 20 or more, it is desirable that the depth of the
• counterbore portion 27 from the end portion 20e to the bottom portion 27a be set to 3 mm or more.
• the energy storage device 100 is an energy storage device which includes : the electrode assembly 20 formed by stacking the positive electrode 21 and the negative electrode 22; and the container 10.
• the energy storage device 100 includes the safety valve 70 formed on the lid member 12 which forms the wall portion of the container 10.
• the notched portions 21ad and/or the notched portions 22ad extending in a direction away from the lid member 12 are formed on the edge 21ab of the positive electrode 21 and/or the edge 22ab of the negative electrode 22 disposed adjacently to the lid member 12, the positive electrode 21 or the negative electrode 22 of at least one layer.
• the notched portions 2 lad and 22ad can ensure a space between the electrode assembly 20 and the lid member 12. Accordingly, it is possible to prevent the safety valve 70 from being closed by the electrode assembly 20 and hence, the increased pressure can be released in a stable manner.
• the notched portion 2 lad and/or the notched portion 22ad faces the safety valve 70.
• the notched portions 2 lad and 22ad can ensure a space at a position where the notched portions 2 lad and 22ad face the safety valve 70 in an opposed manner and hence, it is possible to more easily prevent the electrode assembly 20 from closing the safety valve 70.
• the electrode assembly 20 is configured such that the electrode assembly 20 is formed by winding the positive electrode 21 and the negative electrode 22, and the winding axis A of the electrode assembly 20 intersects with the lid member 12.
• the plurality of notched portions 21ad and 22ad are formed in the positive electrode 21 and the negative electrode 22 such that the notched portions 2 lad and 22ad are arranged in a row in a direction along which the positive electrode 21 and the negative electrode 22 are stacked to each other.
• spaces formed by the plurality of notched portions 2 lad and 22ad overlap with each other in a direction along which the positive electrode 21 and the negative electrode 22 are stacked to each other. Accordingly, the plurality of notched portions 2 lad and 22ad increase a space defined between the electrode assembly 20 and the lid member 12 of the container 10 and hence, it is possible to more easily prevent the electrode assembly 20 from closing the safety valve 70.
• the positive electrode 21 and the negative electrode 22 have the positive electrode collector tabs 21aa and the negative electrode collector tabs 22aa projecting from the edges 2 lab and 22ab, respectively, disposed adjacently to the lid member 12 at positions different from the notched portions 21ad and 22ad.
• the notched portions 21ad and 22ad are formed in an indented manner from the edge 2 lab of the positive electrode 21 and the edge 22ab of the negative electrode 22 on which the positive electrode collector tabs 21aa and the negative electrode collector tabs 22aa are formed, respectively, in a direction further away from the lid member 12 of the container 10.
• the notched portions 21ad and 22ad can ensure a space defined between the electrode assembly 20 and the lid member 12 of the container 10.
• an energy storage device 200 is an energy storage device which includes a vertical-winding-type electrode assembly.
• an electrode assembly 220 of the energy storage device 200 is arranged in the container body 11 in a direction that end portions 220e and 220f of the electrode assembly 220 in the direction of a winding axis A face short side walls lid and llf of the container body 11. That is, the winding axis A of the electrode assembly 220 extends in direction along an outer surface 12a of a lid member 12.
• Fig. 7 is an exploded perspective view substantially equal to Fig. 2 showing a configuration of the energy storage device 200 which is the modification of the energy storage device 100 according to the embodiment of the present invention.
• the electrode assembly 220 is formed such that one positive electrode 221, one negative electrode 222 and two separators 23 which overlap with each other are spirally wound together in a winding direction B about the winding axis A.
• Fig. 8 is a perspective view showing a portion of the electrode assembly 220 shown in Fig. 7 in a developed manner.
• a positive electrode substrate 221a of a positive electrode 221 does not include positive electrode collector tabs.
• a positive active material layer 21b is laminated to substantially the whole positive electrode substrate 221a. However, the positive active material layer 21b is not laminated to a positive electrode non-coated portion 221ad which is a strip-like region disposed in the vicinity of one edge out of two edges of the positive electrode substrate 221a extending in a longitudinal direction.
• a plurality of positive electrode opening portions 221c having a rectangular shape are formed in the positive electrode 221 such that the positive electrode opening portions 221c penetrate the positive electrode substrate 221a and the positive active material layer 21b.
• the plurality of positive electrode opening portions 221c are formed in the positive electrode 221 at intervals along a longitudinal direction of the positive electrode 221. Further, the plurality of positive electrode opening portions 221c are positioned at substantially the center of the positive active material layer 21b in a lateral direction perpendicular to the longitudinal direction of the rectangular strip-like positive electrode 221.
• the positive electrode opening portions 221c can be formed such that portions having a rectangular shape are cut out from the positive electrode substrate 221a by laser cutting or the like, or portions having a rectangular shape are punched out from the positive electrode substrate 221a using a die or the like.
• the positive electrode opening portions 221c are arranged on the positive electrode 221 such that one positive electrode opening portion 221c is formed on the positive electrode 221 for every one turn about the winding axis A. Further, the plurality of positive electrode opening portions 221c are substantially aligned in a row in a stacking direction of the positive electrode 221 after winding.
• a negative electrode substrate 222a of a negative electrode 222 does not include negative electrode collector tabs.
• a negative active material layer 22b is laminated to substantially the whole negative electrode substrate 222a. However, the negative active material layer 22b is not laminated to a negative electrode non-coated portion 222ad which is a strip-like region disposed in the vicinity of one edge out of two edges of the negative electrode substrate 222a extending in a longitudinal direction.
• the negative electrode 221 and the negative electrode 222 are made to overlap with each other for winding, the negative electrode
• non-coated portion 222ad is positioned on a side opposite to the positive electrode non-coated portion 221ad.
• a plurality of negative electrode opening portions 222c having a rectangular shape are formed in the negative electrode 222 such that the negative electrode opening portions 222c penetrate the negative electrode substrate 222a and the negative active material layer 22b.
• the negative electrode opening portion 222c has the same shape as the positive electrode opening portion 221c. However, a size of the negative electrode opening portion 222c is set to be smaller than a size of the positive electrode opening portion 221c.
• the negative electrode opening portion 222c may not have the same shape as the positive electrode opening portion 221c. However, it is preferable that the negative electrode opening portion 222c have the same shape as the positive electrode opening portion 221c in terms of manufacture.
• the plurality of negative electrode opening portions 222c are formed in the negative electrode 222 at intervals along a longitudinal direction of the negative electrode 222. Further, the plurality of negative electrode opening portions 222c are positioned at substantially the center of the negative active material layer 22b in a lateral direction perpendicular to the longitudinal direction of the rectangular strip-like negative electrode 222.
• the negative electrode opening portions 222c can be formed such that portions having a rectangular shape are cut out from the negative electrode substrate 222a by laser cutting or the like, or portions having a rectangular shape are punched out from the negative electrode substrate 222a using a die or the like.
• the negative electrode opening portions 222c are arranged on the negative electrode 222 such that one negative electrode opening portion 222c is formed on the negative electrode 222 for every one turn about the winding axis A. Further, the plurality of negative electrode opening portions 222c are formed such that, after winding, the negative electrode opening portions 222c are substantially arranged in a row in a direction along which the positive electrode 221 and the negative electrode 222 are stacked to each other, and the negative electrode opening portions 222c are also
• the respective negative electrode opening portion 222c are formed on the negative electrode 222 so as to overlap with the respective positive electrode opening portions 221c in an aligned manner when the positive electrode 221 and the negative electrode 222 are made to overlap with each other for winding.
• the negative electrode opening portion 222c be positioned inside the positive electrode opening portion 221c.
• the separators 23 are formed on main surfaces formed on both sides of the negative electrode 222 so as to cover the whole negative electrode 222 except for the negative electrode non-coated portion 222ad.
• the negative electrode non-coated portion 222ad projects while passing through between two separators 23.
• the whole positive electrode 221 except for the positive electrode non-coated portion 221ad is covered by the negative electrode 222 and the separator 23.
• the whole positive active material layer 21b of the positive electrode 221 which is made to overlap with the negative electrode 222 faces the negative active material layer 22b.
• the positive electrode non-coated portion 221ad projects from the separators 23 on a side opposite to the negative electrode non-coated portion 222ad.
• the positive electrode 221 is disposed such that the positive electrode 221 is positioned inside the separator 23 disposed adjacently to the inside of the negative electrode 222 at the time of winding.
• the positive electrode opening portions 221c and the negative electrode opening portions 222c are positioned at a bent wall portion 220c of the electrode assembly 220.
• the positive electrode opening portions 221c and the negative electrode opening portions 222c are positioned such that a center portion of the positive electrode opening 221c in the winding direction B and a center portion of the negative electrode opening portion 222c in the winding direction B are positioned at a projecting edge end 220ca of the bent wall portion 220c.
• the projecting edge end 220ca of the bent wall portion 220c is an edge end of the bent wall portion 220c which projects the most toward the outside in a Z axis direction which is a lateral direction of flat wall portions 220a and 220b of the electrode assembly 220, and extends along the winding axis A. That is, the projecting edge end 220ca is a portion which is positioned at a top portion of the bent wall portion 220c in the lateral direction of the flat wall portions 220a and 220b, and is disposed most closely to the lid member 12 when the electrode assembly 220 is housed in the container 10.
• the positive electrode opening portions 221c and the negative electrode opening portions 222c form a counterbore portion 227 in the bent wall portion 220c, wherein the counterbore portion 227 is a recessed portion having a semicircular columnar shape extending from the projecting edge end 220ca to the winding axis A, that is, to the bent wall portion 220d.
• the separators 23 extend in the counterbore portion 227.
• the separators 23 may have opening portions having the same shape as the positive electrode opening portions 221c and the negative electrode opening portions 222c and substantially aligned with the positive electrode opening portions 221c and negative electrode opening portions 222c in position.
• a size of the opening portions formed in the separators 23 is set to be smaller than a size of the positive electrode opening portions 221c and a size of the negative electrode opening portions 222c. It is desirable that the opening portions formed in the separators 23 be positioned inside the positive electrode opening portions 221c and negative electrode opening portions 222c when the separators 23, the positive electrode 221 and the negative electrode 222 are made to overlap with each other.
• the opening portions formed in the separators 23 may not have the same shape as the positive electrode opening portions 221c and the negative electrode opening portions 222c. However, it is preferable that the opening portions formed in the separators 23 have the same shape as the positive electrode opening portions 221c and the negative electrode opening portions 222c in terms of manufacture. Even in the case where the separators 23 having a large number of pores do not have the above-mentioned opening portions which correspond to the counterbore portion 227 and extend in the counterbore portion 227, a sufficient amount of gas is allowed to pass through the inside of the counterbore portion 227.
• the counterbore portion 227 is surrounded by: a flat bottom portion 227a on a winding axis A side! and side surface portions 227b and 227c erected upright toward the projecting edge end 220ca from both ends of the bottom portion 227a in the direction of the winding axis A.
• the counterbore portion 227 is opened in a direction from the bottom portion 227a to the projecting edge end 220ca, in a direction from the flat wall portion 220a to the flat wall portion 220b, and in a direction from the flat wall portion 220b to the flat wall portion 220a. That is, the counterbore portion 227 is opened from the bottom portion 227a in directions along which the positive electrode 221 and the negative electrode 222 are stacked to each other.
• the positive electrode opening portion 221c is positioned in each turn of the positive electrode 221 such that a center portion of the positive electrode opening portion 221c in the winding direction B is positioned at a projecting edge end 221d of the positive electrode 221 which projects the most toward the projecting edge end 220ca from the winding axis A and extends in the direction of the winding axis A.
• the positive electrode opening portions 221c form a recessed portion indented toward the winding axis A from the projecting edge end 221d in the positive electrode 221.
• the negative electrode opening portion 222c is also positioned in each turn of the negative electrode 222 such that a center portion of the negative electrode opening portion 222c in the winding direction B is positioned at a projecting edge end 222d of the negative electrode 222 which projects the most toward the projecting edge end 220ca from the winding axis A and extends in the direction of the winding axis A.
• the negative electrode opening portion 222c form a recessed portion indented toward the winding axis A from the projecting edge end 221d in the negative electrode 222.
• the above-mentioned projecting edge end 221d of the positive electrode 221 and the above-mentioned projecting edge end 222d of the negative electrode 222 are one example of an edge portion of an electrode plate, and the positive electrode opening portion 221c and the negative electrode opening portion 222c are one example of a recessed portion.
• the wound positive electrode non-coated portion 221ad forms one end portion 220e of the electrode assembly 220 in the direction of the winding axis A
• the wound negative electrode non-coated portion 222ad forms the other end portion 220f of the electrode assembly 220 in the direction of the winding axis A.
• the electrode assembly 220 is formed so as to have a flat elongated circular cross-sectional shape.
• a cross-sectional shape of the electrode assembly 220 may be a shape other than an elongated circular shape, and may be a circular shape, an elliptic type, a rectangular shape, or other polygonal shapes.
• the positive electrode non-coated portion 221ad of the electrode assembly 220 is electrically connected to the positive electrode terminal 30 of the lid member 12 of the container 10 through a positive electrode collector 250 and, at the same time, is fixed to the lid member 12.
• the negative electrode non-coated portion 222ad of the electrode assembly 220 is electrically connected to the negative electrode terminal 40 of the lid member 12 through a negative electrode collector 260 and, at the same time, is fixed to the lid member 12.
• the positive electrode collector 250 is made of the same material as the positive electrode substrate 221a.
• the negative electrode collector 260 is made of the same material as the negative electrode substrate 222a.
• the positive electrode collector 250 is fixed to the terminal body 31 by riveting using a rivet portion 31a formed on the terminal body 31 of the positive electrode terminal 30. Further, two leg portions 250a which the positive electrode collector 250 includes are assembled to the positive electrode non-coated portion 221ad bundled in the stacking direction such that the leg portions 250a sandwich the positive electrode non-coated portion 221ad from both sides of the positive electrode non-coated portion 221ad. Two leg portions 250a are joined to the positive electrode non-coated portion 22 lad by welding or the like.
• the upper insulating member 32 electrically insulates the terminal body 31 and the lid member 12 from each other, and the lower insulating member 33 electrically insulates the lid member 12 and the positive electrode collector 250 from each other.
• the negative electrode collector 260 is fixed to the terminal body 41 by riveting using a rivet portion 41a formed on the terminal body 41 of the negative electrode terminal 40. Further, two leg portions 260a which the negative electrode collector 260 includes are assembled to the negative electrode non-coated portion 222ad bundled in the stacking direction such that the leg portions 260a sandwich the negative electrode non-coated portion 222ad from both sides of the negative electrode non-coated portion 222ad. Two leg portions 260a are joined to the negative electrode
• the upper insulating member 42 electrically insulates the terminal body 41 and the lid member 12 from each other, and the lower insulating member 43 electrically insulates the lid member 12 and the negative electrode collector 260 from each other.
• the electrode assembly 220 is mounted on the lid member 12 such that the projecting edge end 220ca on which the counterbore portion 227 is formed is disposed adjacently to the lid member 12. That is, in the electrode assembly 220, the projecting edge end 220ca is disposed most closely to the lid member 12.
• the counterbore portion 227 is positioned so as to face the safety valve 70 in an opposed manner. In a direction toward the negative electrode terminal 40 from the positive electrode terminal 30, that is, in the X axis direction, a width of the counterbore portion 227 between the side surface portion 227b and the side surface portion 227c is set to be larger than a width of the weakened portion 71 of the safety valve 70.
• a width of the counterbore portion 227 between the open ends is set to be larger than a width of the weakened portion 71 of the safety valve 70. Further, the whole weakened portion 71 of the safety valve 70 faces the counterbore portion 227.
• the counterbore portion 227 ensures a space at a position where the counterbore portion 227 faces the safety valve 70 in an opposed manner.
• the counterbore portion 227 can ensure a sufficient space at a position where the counterbore portion 227 faces the safety valve 70 in an opposed manner.
• the present invention is not limited to the embodiment and the modification. That is, it should be construed that the embodiment and the modification disclosed this time are provided only for an exemplifying purpose in all aspects and are not limitative of the present invention.
• the scope of the present invention is not designated by the above-mentioned description but is designated by Claims, and it is intended that all modifications which fall within the meaning and the scope equivalent to Claims are also included in the scope of the present invention.
• the electrode assembly is the winding-type electrode assembly formed by winding the positive electrode, the negative electrode and the separators which are stacked to each other.
• the electrode assembly is not limited to such a winding-type electrode assembly.
• the electrode assembly may be a stack-type electrode assembly formed by stacking a large number of positive electrodes, a large number of negative electrodes and a large number of separators to each other.
• the electrode assembly may be a Z-type electrode assembly formed by bending a positive electrode, a negative electrode and separators which are stacked to each other plural times.
• the counterbore portion of the electrode assembly has a rectangular parallelepiped shape.
• the shape of the counterbore portion is not limited to a rectangular parallelepiped shape.
• counterbore portion may have a columnar shape such as a semicircular columnar shape, a semi- elliptical columnar shape, a triangular columnar shape or a polygonal columnar shape where a cross- sectional shape does not change in a direction extending between two flat wall portions of the electrode assembly.
• a plurality of notched portions formed in the positive electrode and the negative electrode have the same shape and hence, the positive electrode substrate and the negative electrode substrate can be easily worked.
• the counterbore portion may have a shape such as a semispherical shape or a semi- elliptical spherical shape where a cross- sectional shape changes in a direction extending between two flat wall portions of the electrode assembly.
• the counterbore portion 27 is disposed away from the positive electrode collector tab group 24 and the negative electrode collector tab group 25. That is, the edge 21ab of the positive electrode 21 and the edge 22ab of the negative electrode 22 are interposed between the counterbore portion 227 and the positive electrode collector tab group 24 as well as between the counterbore portion 227 and the negative electrode collector tab group 25.
• the counterbore portion 27 may be disposed adjacently to either one of the positive electrode collector tab group 24 and the negative electrode collector tab group 25 without interposing the edge 21ab between the counterbore portion 27 and the positive electrode collector tab group 24 or without interposing the edge 22ab between the counterbore portion 27 and the negative electrode collector tab group 25.
• the counterbore portion 227 has the flat bottom portion 227a.
• the electrode assembly 220 is not limited to such a configuration.
• the positive electrode opening portions 221c formed on the positive electrode 221 and the negative electrode opening portions 222c formed on the negative electrode 222 may have a counterbore portion where the center of a bottom portion of the counterbore portion is indented.
• the notched portions or the positive electrode opening portions are formed in all layers of the positive electrode stacked in layers at portions corresponding to the counterbore portion. Further, the notched portions or the negative electrode opening portions are formed in all layers of the negative electrode stacked in layers at portions corresponding to the counterbore portion.
• the present invention is not limited to such a configuration. Notched portions or opening portions may be formed only on either one of the positive electrode and the negative electrode.
• the notched portions or the opening portions are formed in either one of the positive electrode and the negative electrode and the case where the notched portions or the opening portions are formed in both the positive electrode and the negative electrode, it is sufficient to form the notched portion or the positive electrode opening portion in at least one layer of the positive electrode stacked in layers, or it is sufficient to form the notched portion or the negative electrode opening portion in at least one layer of the negative electrode stacked in layers.
• the energy storage device according to the embodiment and the energy storage device according to the modification include one electrode assembly 20.
• each energy storage device may include two or more electrode assemblies.
• the electrode assembly 20 is configured such that the positive electrode collector tab group 24 and the negative electrode collector tab group 25 are formed on the end portion 20e.
• the electrode assembly may be configured such that the electrode assembly has neither the positive electrode collector tab group 24 nor the negative electrode collector tab group 25, and a strip-like positive electrode non-coated portion and a strip-like negative electrode non-coated portion are formed on two end portions of the electrode assembly in the direction of a winding axis A, respectively, as in the case of the electrode assembly 220 of the energy storage device 200 according to the modification.
• the positive electrode non-coated portion and the negative electrode non-coated portion are connected to a positive electrode collector and a negative electrode collector, respectively.
• the electrode assembly 220 is configured to be connected to the positive electrode collector 250 and the negative electrode collector 260 through the positive electrode non-coated portion 221ad and the negative electrode non-coated portion 222ad, respectively.
• the present invention is not limited to such a configuration.
• the energy storage device may be configured such that the electrode assembly includes tabs formed on the positive electrode substrate 221a of the positive electrode 221 and the negative electrode substrate 222a of the negative electrode 222 in a projecting manner as integral parts thereof at a position of the positive electrode non-coated portion 221ad and a position of the negative electrode non-coated portion 222ad, respectively.
• the positive electrode collector 250 and the negative electrode collector 260 may be connected to the tabs.
• the electrode assembly 220 has the counterbore portion 227 at the projecting edge end 220ca of the bent wall portion 220c.
• the electrode assembly 220 may have a counterbore portion at the end portion 220e or 220f of the electrode assembly 220 in the direction of the winding axis A.
• the counterbore portion of the electrode assembly 220 may have
• the positive electrode collector 250 and the negative electrode collector 260 extending from the lid member 12 of the container 10 are connected to the positive electrode non-coated portion 221ad and the negative electrode non-coated portion 222ad, respectively.
• the safety valve is formed on the short side wall lid or llf of the container body 11 of the container 10 which faces the counterbore portion in an opposed manner. Still further, the safety valve formed on the short side wall lid or llf may be disposed at a position where the safety valve faces the counterbore portion in an opposed manner.
• the separators 23 have neither notched portions nor opening portions, and extend in the counterbore portion.
• the present invention is not limited to such a configuration.
• Notched portions or opening portions substantially equal to the notched portions or the opening portions formed in the positive electrode substrate and the negative electrode substrate may be formed also in the separators 23.
• the configurations which are made by arbitrarily combining the embodiment and the modification are also included in the scope of the present invention.
• the present invention can realize not only the above-mentioned energy storage device but also an energy storage apparatus including one or more energy storage device.
• the present invention is applicable to an energy storage device such as a lithium ion secondary battery and the like.

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