JP6015595B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device.

  A battery having a current interrupt device (CID: Current Interrupt Device) that cuts off a current flowing between an electrode assembly housed in the case and a terminal attached to the case when the pressure in the case becomes higher than a set value. Is known (see, for example, Patent Document 1).

JP 2010-157451 A

  The current interrupt device is arranged in the case. For example, the bottom surface of the current interrupt device is disposed to face the top surface of the electrode assembly. An opening is formed in the bottom surface of the current interrupt device. The gas in the case is introduced into the current interrupt device through the opening.

  The electrode assembly may expand due to expansion of the active material, for example. In this case, the upper surface of the electrode assembly may come into contact with the bottom surface of the current interrupt device to close the opening. When the opening is closed, the gas in the case is not introduced into the current interrupt device, and the current interrupt device does not operate at a desired pressure.

  An object of this invention is to provide the electrical storage apparatus which can operate an electric current interruption apparatus with a desired pressure.

  A power storage device according to one aspect of the present invention includes a case, an electrode assembly housed in the case, a current interrupt device that is disposed in the case and interrupts current according to pressure in the case, The electrode assembly includes a positive electrode, a negative electrode, and a separator that insulates the positive electrode from the negative electrode, and the current interrupt device has a bottom surface in which an opening is formed. The electrode assembly is disposed on the electrode assembly side, and the electrode assembly has a facing surface facing the bottom surface of the current interrupt device, and the facing surface has a recess facing the opening, The recess extends from the outside of at least a part of the outer edge of the bottom surface to the inside of the edge of at least a part of the opening when viewed from the normal direction of the facing surface.

  In this power storage device, even if the electrode assembly expands, the opposing surface of the electrode assembly is suppressed from blocking the opening on the bottom surface of the current interrupt device. Therefore, the gas in the case can reach the space in the opening through the space in the recess. Therefore, the current interrupt device can be operated at a desired pressure.

  The recess extends in a first direction along the facing surface, and in the second direction along the facing surface and perpendicular to the first direction, the width of the recess is equal to the current interrupting device. It may be smaller than the width of the bottom surface.

  In this case, even if the opposing surface of the electrode assembly and the bottom surface of the current interrupt device come into contact, the gas in the case can reach the space in the opening through the space in the recess. In addition, since the volume of the electrode assembly can be increased as much as possible, the capacity of the power storage device can be increased.

  The concave portion may cover the bottom surface of the current interrupt device when viewed from the normal direction of the facing surface.

  In this case, the distance between the opposing surface of the electrode assembly and the bottom surface of the current interrupt device can be increased. As a result, even if the electrode assembly expands, it is possible to reduce the possibility that the facing surface of the electrode assembly contacts the bottom surface of the current interrupt device and the opening is blocked.

  The bottom surface of the current interrupt device may be located in the recess.

  In this case, the power storage device can be reduced in size.

  The electrode assembly has a structure in which a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators are stacked, and the recess includes the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators. You may penetrate in the laminating direction.

  In this case, each of the positive electrode, the negative electrode, and the separator can have the same shape. Therefore, manufacture of a positive electrode, a negative electrode, and a separator becomes easy.

  The positive electrode may include a positive electrode tab, the negative electrode may include a negative electrode tab, and the positive electrode tab and the negative electrode tab may be provided on the facing surface.

  In this case, the distance between the positive electrode tab and the negative electrode tab and the current interrupt device can be shortened.

  The power storage device may be a secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage apparatus which can operate an electric current interruption apparatus with a desired pressure can be provided.

It is sectional drawing which shows typically the electrical storage apparatus which concerns on one Embodiment. It is a figure which shows typically a part of electrical storage apparatus which concerns on one Embodiment. It is a figure which shows typically a part of electrical storage apparatus which concerns on other embodiment. It is a figure which shows typically a part of electrical storage apparatus which concerns on other embodiment. It is a figure which shows typically a part of electrical storage apparatus which concerns on other embodiment. It is a figure which shows typically a part of electrical storage apparatus which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and redundant descriptions are omitted. In the drawing, an XYZ orthogonal coordinate system is shown. The X direction, the Y direction, and the Z direction are orthogonal to each other.

  FIG. 1 is a cross-sectional view schematically showing a power storage device according to an embodiment. FIG. 2 is a diagram schematically showing a part of the power storage device of FIG. 1 and 2 is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The secondary battery 100 includes a case 10 and an electrode assembly 20 accommodated in the case 10.

  The case 10 has conductivity and may be made of a metal such as aluminum or an aluminum alloy. The case 10 has a rectangular parallelepiped shape, for example.

  The electrode assembly 20 has a rectangular parallelepiped shape, for example. The electrode assembly 20 may include an upper surface 20A, a lower surface 20B, two side surfaces 20C, and two side surfaces 20D. The upper surface 20A and the lower surface 20B are planes parallel to the XY plane. The side surface 20C is a plane parallel to the XZ plane. The side surface 20D is a plane parallel to the YZ plane. The shapes of the upper surface 20A, the lower surface 20B, the side surface 20C, and the side surface 20D are, for example, rectangular.

  The electrode assembly 20 includes a positive electrode 30, a negative electrode 40, and a separator 50 that insulates the positive electrode 30 and the negative electrode 40. The positive electrode 30 and the negative electrode 40 are, for example, in sheet form. The separator 50 is, for example, a bag shape, but may be a sheet shape. For example, the positive electrode 30 is accommodated in the bag-shaped separator 50. The electrode assembly 20 may have a structure in which a plurality of positive electrodes 30, a plurality of negative electrodes 40, and a plurality of separators 50 are stacked in the Y direction. The negative electrode 40 is larger than the positive electrode 30 when viewed from the Y direction. The case 10 can be filled with the electrolytic solution 60. Examples of the electrolytic solution 60 include an organic solvent-based or non-aqueous electrolytic solution.

  The positive electrode 30 can include a metal foil and a positive electrode active material layer provided on both surfaces of the metal foil. The metal foil is, for example, an aluminum foil or an aluminum alloy foil. The positive electrode active material layer may include a positive electrode active material and a binder. Examples of the positive electrode active material include composite oxide, metallic lithium, and sulfur. The composite oxide includes at least one of manganese, nickel, cobalt, and aluminum and lithium.

  The positive electrode 30 may have a positive electrode tab 30A formed at the edge. The positive electrode tab 30 </ b> A may be provided on the upper surface 20 </ b> A of the electrode assembly 20. The positive electrode active material is not supported on the positive electrode tab 30A. The positive electrode 30 can be connected to the conductive member 32 via the positive electrode tab 30A. The conductive member 32 can be connected to the positive terminal 34. The positive electrode terminal 34 may be attached to the case 10 via an insulating ring 36.

  The negative electrode 40 may include a metal foil and a negative electrode active material layer provided on both surfaces of the metal foil. The metal foil is, for example, a copper foil or a copper alloy foil. The negative electrode active material layer may include a negative electrode active material and a binder. Examples of the negative electrode active material include carbon such as graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon, alkali metals such as lithium and sodium, metal compounds, SiOx (0.5 ≦ x ≦ 1.5 ) And the like, and boron-added carbon.

  The negative electrode 40 may have a negative electrode tab 40A formed at the edge. The negative electrode tab 40 </ b> A may be provided on the upper surface 20 </ b> A of the electrode assembly 20. The negative electrode active material is not supported on the negative electrode tab 40A. The negative electrode 40 can be connected to the conductive member 42 via the negative electrode tab 40A. The conductive member 42 can be connected to the negative terminal 44. The negative electrode terminal 44 may be attached to the case 10 via the insulating ring 46.

  Examples of the separator 50 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven fabric or a non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose, and the like.

  The secondary battery 100 includes a current interrupt device 70 disposed in the case 10. The current interrupt device 70 may be attached to the case 10 by an insulating member, for example. The current interrupt device 70 interrupts the current flowing through the electrode assembly 20 according to the pressure in the case 10. The current interrupt device 70 may be provided in the middle of the conductive member 42. When the pressure in the case 10 becomes equal to or higher than the threshold, the current interrupt device 70 interrupts the current flowing through the conductive member 42.

  The current interrupt device 70 has a bottom surface 70A in which an opening 76 is formed. The bottom surface 70A is disposed on the electrode assembly 20 side. The bottom surface 70A is a plane parallel to the XY plane. The shape of the bottom surface 70A and the opening 76 is, for example, a circle or an ellipse, but may be a rectangle. The current interrupt device 70 may include a ring-shaped casing 72 in which a through hole extending in the Z direction is formed, and a conductive plate 74 that closes the through hole of the casing 72. The conductive plate 74 can be disposed at the center of the housing 72 in the Z direction. The conductive plate 74 is electrically connected to the conductive member 42. The conductive plate 74 is curved so as to protrude downward in the Z direction. A lower end portion of the housing 72 forms an opening 76. When the gas is introduced into the current interrupt device 70 from the opening 76, the conductive plate 74 is pressed upward in the Z direction. When the pressure in the case 10 increases and reaches a threshold value, the conductive plate 74 is broken and the current is interrupted.

  The current interrupt device 70 may further include a flat conductive plate that contacts the protrusion of the conductive plate 74. In this case, when the pressure in the case 10 increases and reaches a threshold value, the conductive plate 74 is deformed and curved so as to protrude upward in the Z direction. As a result, the projecting portion of the conductive plate 74 and the flat conductive plate are not in contact with each other, so that the current is interrupted. The conductive plate 74 functions as a reverse plate.

  The upper surface 20 </ b> A of the electrode assembly 20 is a facing surface that faces the bottom surface 70 </ b> A of the current interrupt device 70. The upper surface 20 </ b> A has a recess 22 that faces the opening 76 of the current interrupt device 70. The recess 22 can be formed by the upper surface 20A being recessed in the Z direction.

  Recess 22 extends from the outside of at least a portion of outer edge 70B of bottom surface 70A of current interrupting device 70 to the inside of at least a portion of outer edge 76B of opening 76 when viewed from the normal direction (Z direction) of upper surface 20A. It is extended. In the present embodiment, the recess 22 extends in the X direction (first direction) along the upper surface 20A. As viewed from the Z direction, the shape of the concave portion 22 is, for example, a rectangular shape, but may be a circular shape, an elliptical shape, or a ring shape. In the X direction, the length of the recess 22 is longer than the length of the bottom surface 70 </ b> A of the current interrupt device 70. In the Y direction (second direction) along the top surface 20A, the width D1 of the recess 22 is smaller than the width D2 of the bottom surface 70A of the current interrupt device 70.

  The recess 22 can be formed, for example, by forming a notch in the metal foil of the negative electrode 40 and the separator 50. When viewed from the stacking direction (Y direction), the metal foil of the negative electrode 40 is larger than the metal foil of the positive electrode 30. Therefore, the recess 22 can be formed without forming a notch in the metal foil of the positive electrode 30. As viewed from the Y direction, a metal foil as a blank remains around the negative electrode active material layer of the negative electrode 40.

  In the secondary battery 100, for example, even when the electrode assembly 20 expands due to expansion of the active material, the upper surface 20 </ b> A of the electrode assembly 20 is suppressed from closing the opening 76 of the bottom surface 70 </ b> A of the current interrupt device 70. Therefore, the gas in the case 10 can reach the space in the opening 76 through the space in the recess 22. Therefore, the current interrupt device 70 can be operated at a desired pressure.

  In the present embodiment, the recess 22 extends in the X direction, and the width D1 of the recess 22 is smaller than the width D2 of the bottom surface 70A of the current interrupt device 70. Therefore, even if the upper surface 20A of the electrode assembly 20 and the bottom surface 70A of the current interrupt device 70 are in contact with each other, the space in the case 10 and the space in the opening 76 remain in communication via the space in the recess 22. Become. Therefore, the gas in the case 10 can reach the space in the opening 76 through the space in the recess 22. Therefore, since the design distance between the upper surface 20A of the electrode assembly 20 and the bottom surface 70A of the current interrupt device 70 can be shortened, the secondary battery 100 can be reduced in size. Moreover, since the space in the recessed part 22 may be small, the volume of the electrode assembly 20 can be increased as much as possible. Therefore, the capacity of the secondary battery 100 can be increased.

  When the positive electrode tab 30A and the negative electrode tab 40A are provided on the upper surface 20A, the distance between the positive electrode tab 30A and the negative electrode tab 40A and the current interrupt device 70 can be shortened. As a result, the conductive member 42 can be shortened as much as possible.

  FIG. 3 is a diagram schematically illustrating a part of a power storage device according to another embodiment. The secondary battery as the power storage device according to the present embodiment has the same structure as the secondary battery 100 except that the recess 22A is provided instead of the recess 22.

  The recess 22A covers the bottom surface 70A of the current interrupt device 70 when viewed from the Z direction. Therefore, the distance between the upper surface 20A of the electrode assembly 20 and the bottom surface 70A of the current interrupt device 70 can be increased. As a result, even if the electrode assembly 20 expands due to expansion of the active material, for example, the possibility that the upper surface 20A of the electrode assembly 20 contacts the bottom surface 70A of the current interrupt device 70 and the opening 76 is blocked is reduced. .

  FIG. 4 is a diagram schematically illustrating a part of a power storage device according to another embodiment. The secondary battery as the power storage device according to the present embodiment has the same structure as the secondary battery 100 except that the recess 22B is provided instead of the recess 22.

  The recess 22B penetrates in the Y direction (stacking direction). Therefore, each of the positive electrode 30, the negative electrode 40, and the separator 50 can have the same shape. Therefore, since the same type can be used, manufacture of the positive electrode 30, the negative electrode 40, and the separator 50 becomes easy. In the X direction, the width of the recess 22 </ b> B may be smaller than the width of the bottom surface 70 </ b> A of the current interrupt device 70.

  FIG. 5 is a diagram schematically illustrating a part of a power storage device according to another embodiment. The secondary battery as the power storage device according to the present embodiment is the same as the secondary battery of FIG. 3 except that the bottom surface 70A of the current interrupt device 70 is located in the recess 22A when viewed from the stacking direction of the electrode assembly 20. Have the same structure. In this case, the secondary battery can be downsized. The recess 22A may be replaced with the recess 22B.

  FIG. 6 is a diagram schematically illustrating a part of a power storage device according to another embodiment. The secondary battery as the power storage device according to the present embodiment has the same structure as the secondary battery of FIG. 5 except that the recess 22C is provided instead of the recess 22A. The depth of the recess 22C is deeper than the depth of the recess 22A. The recess 22 </ b> C is formed not only by forming a notch in the metal foil of the negative electrode 40 and the separator 50, but also by forming a notch in the metal foil of the positive electrode 30. As viewed from the Y direction, a metal foil as a blank remains around the positive electrode active material layer of the positive electrode 30. The recess 22A may be replaced with the recess 22B.

  As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment.

  For example, each component in each embodiment can be arbitrarily combined.

  A plurality of recesses 22, 22A, 22B, and 22C may be formed on the upper surface 20A. Further, the recesses 22, 22 </ b> A, 22 </ b> B, and 22 </ b> C may be formed on the side surface 20 </ b> C of the electrode assembly 20. In this case, the current interrupt device 70 is disposed between the side surface 20 </ b> C (opposing surface) of the electrode assembly 20 and the case 10. Similarly, the recesses 22, 22 </ b> A, 22 </ b> B, and 22 </ b> C may be formed on the side surface 20 </ b> D of the electrode assembly 20. In this case, the current interrupt device 70 is disposed between the side surface 20 </ b> D (opposing surface) of the electrode assembly 20 and the case 10.

  A wound electrode assembly may be used instead of the stacked electrode assembly 20. The wound electrode assembly is manufactured by winding a belt-like positive electrode 30, a negative electrode 40, and a separator 50 around an axis.

  As the power storage device, in addition to the secondary battery 100, for example, an electric double layer capacitor or the like can be given.

  For example, a power storage device such as the secondary battery 100 may be mounted on the vehicle. Examples of the vehicle include an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, an electric wheelchair, an electrically assisted bicycle, and an electric motorcycle.

  DESCRIPTION OF SYMBOLS 10 ... Case, 20 ... Electrode assembly, 20A ... Upper surface (opposite surface), 22, 22A, 22B, 22C ... Recess, 30 ... Positive electrode, 30A ... Positive electrode tab, 40 ... Negative electrode, 40A ... Negative electrode tab, 50 ... Separator, DESCRIPTION OF SYMBOLS 70 ... Current interruption | blocking apparatus, 70A ... Bottom surface, 70B ... Outer edge, 76 ... Opening part, 76B ... Outer edge, 100 ... Secondary battery (electric storage apparatus).

Claims (7)

Case and
An electrode assembly housed in the case;
A current interrupting device disposed in the case and configured to interrupt a current according to a pressure in the case;
With
The electrode assembly includes a positive electrode, a negative electrode, and a separator that insulates the positive electrode and the negative electrode.
The current interrupt device has a bottom surface formed with an opening,
The bottom surface is disposed on the electrode assembly side;
The electrode assembly has a facing surface facing the bottom surface of the current interrupt device;
On the facing surface, a recess facing the opening is formed,
The power storage device, wherein the recess extends from the outer side of at least a part of the outer edge of the bottom surface to the inner side of the outer edge of at least a part of the opening when viewed from the normal direction of the facing surface. The recess extends in a first direction along the facing surface;
2. The power storage device according to claim 1, wherein a width of the concave portion is smaller than a width of the bottom surface of the current interrupting device in a second direction along the opposing surface and orthogonal to the first direction.   The power storage device according to claim 1, wherein the recess covers the bottom surface of the current interrupt device when viewed from the normal direction of the facing surface.   The power storage device according to claim 3, wherein the bottom surface of the current interrupt device is located in the recess. The electrode assembly has a structure in which a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators are laminated,
5. The power storage device according to claim 1, wherein the recess penetrates in a stacking direction of the plurality of positive electrodes, the plurality of negative electrodes, and the plurality of separators. The positive electrode has a positive electrode tab;
The negative electrode has a negative electrode tab;
The power storage device according to claim 1, wherein the positive electrode tab and the negative electrode tab are provided on the facing surface.   The power storage device according to any one of claims 1 to 6, wherein the power storage device is a secondary battery.

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