JP2015125902A - Power storge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device in which short circuit of an electrode assembly and a circuit breaker can be suppressed.SOLUTION: A secondary battery 10, a circuit breaker 30, a positive electrode terminal 15 and a negative electrode terminal 16 are arranged in a state where airtightness of a lid 14 is ensured. The secondary battery 10 constitutes the outermost layer of an electrode assembly 12, and has a positive electrode metal layer 24f connected electrically with the positive electrode terminal 15, and a circuit breaker 30 is installed to face the outer surface of the positive electrode metal layer 24f.

Description

  The present invention relates to a power storage device having a wound electrode assembly and a current interrupt device.

  Power storage devices such as secondary batteries and capacitors are widely used as power sources because they can be recharged and can be used repeatedly. Some secondary batteries include an electrode assembly in which a long positive electrode and a negative electrode having an active material layer are wound with a separator interposed therebetween, and a current interruption device ( For example, see Patent Document 1).

  As shown in FIG. 5, the secondary battery 80 of Patent Document 1 includes a wound electrode body 82 as an electrode assembly in a case 81, and the case 81 has an opening for accommodating the wound electrode body 82. The case main body 81a has a lid 83 that closes the opening of the case main body 81a. In addition, the secondary battery 80 includes a negative electrode current collector plate 84 connected to the negative electrode 82 a of the wound electrode body 82. The negative electrode current collector plate 84 is fixed to the lid 83 by a caulking member 84a. A connecting member 85 is fixed to the outer surface side of the lid 83 along with the fixing of the caulking member 84 a to the lid 83. A negative external terminal 86 is fixed to the connection member 85. In the lid 83, an electrically insulating rubber member 97 for ensuring airtightness is provided at a fixed position by the caulking member 84a.

  The secondary battery 80 includes a heat conductor 87 connected to the positive electrode 82b of the wound electrode body 82, and the heat conductor 87 is welded to the side wall 81b of the case body 81a. A side wall 81b of the case body 81a is disposed on one end side in the axial direction of the wound electrode body 82, and a current interrupting element 90 as a current interrupting device is joined to the outer surface of the side wall 81b. Current interrupt device 90 is thermally coupled to thermal conductor 87. Further, the current interruption element 90 is connected to the positive external terminal 92 via the connection member 91. The positive electrode external terminal 92 is connected to another connecting member 99, and the other connecting member 99 is fixed to the lid body 83 by the caulking member 94, whereby the positive electrode external terminal 92 is fixed to the lid body 83. In the lid 83, an electrically insulating rubber member 98 for securing airtightness is provided at a location fixed by the caulking member 94.

  Since the wound electrode body 82 and the side wall portion 81b of the case body 81a are thermally coupled through the heat conductor 87, the heat of the wound electrode body 82 is interrupted through the heat conductor 87 and the side wall portion 81b. It is efficiently transmitted to the element 90. As a result, the current interrupting element 90 interrupts the current at the positive external terminal 92 and appropriately suppresses the excessive temperature rise of the wound electrode body 82.

JP2013-58368A

  As the current interrupting device, in addition to the device that interrupts the current according to the temperature of the wound electrode body 82 like the current interrupting device 90 of Patent Document 1, the current is interrupted when the pressure in the case exceeds the threshold value. There is something. This pressure type current interrupting device is installed in a state where a part of the pressure type current interrupting device can detect the pressure in the case in order to apply the pressure in the case.

  However, when the pressure type current interrupting device is arranged on the side wall 81b of the case main body 81a as in the secondary battery 80 of Patent Document 1, the current interrupting device is installed in the side wall 81b. Airtightness must be ensured. In Patent Document 1, in the lid 83, the electrically insulating rubber members 97 and 98 are provided in the fixing portion by the caulking members 84a and 94 in order to ensure the airtightness, and the portion requiring the airtightness is the lid 83. And the side wall portion 81b. Therefore, it is conceivable to install a current interrupting device on the lid 83 in order to make the part requiring airtightness only one of the lids 83.

  However, when the current interrupting device is installed on the lid 83, the portion of the current interrupting device that detects the pressure in the case 81 approaches the peripheral surface of the wound electrode body 82, and the current interrupting device and the wound electrode body 82 are It becomes easy to short-circuit.

  An object of the present invention is to provide a power storage device that can suppress a short circuit between an electrode assembly and a current interrupt device.

  An electricity storage device for solving the above problems includes an electrode assembly in which a positive electrode and a negative electrode having an active material layer on at least one side of a long metal foil are wound in a state in which both are insulated. A case containing the electrode assembly; a positive terminal electrically connected to the positive electrode; a negative terminal electrically connected to the negative electrode; and a current electrically connected to the positive terminal. A power storage device, wherein the current interrupt device, the positive electrode terminal, and the negative electrode terminal are arranged in a state where airtightness is ensured on one wall portion of the case, The gist is to have a metal layer wound in a state constituting an outer layer and electrically connected to the positive electrode, and the current interrupting device is disposed to face the outer surface of the metal layer. .

  According to this, in order to ensure only one of the wall portions to ensure airtightness, the current interrupting device is provided on one wall portion together with the positive electrode terminal and the negative electrode terminal, and the current interrupting device extends from the wall portion to the electrode assembly. Even if it becomes arrangement | positioning which approaches, the metal layer which an electric current interruption apparatus opposes is the same positive electrode as an electric current interruption apparatus. For this reason, even if a current interruption device and a metal layer contact by vibration etc. of an electrical storage device, it can control that a current interruption device and an electrode assembly short-circuit.

In the power storage device, the metal layer is a positive electrode metal foil included in the positive electrode.
According to this, the material of a positive electrode can be used as a metal layer, and the electrical storage apparatus which has a metal layer can be manufactured easily.

  As for the power storage device, the power storage device may be a secondary battery.

  According to the present invention, a short circuit between the electrode assembly and the current interrupt device can be suppressed.

The partially broken perspective view which shows the secondary battery of embodiment. The perspective view which shows an electrode assembly. The front sectional view showing a secondary battery. Sectional drawing which shows an electrode assembly. The figure which shows background art.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
As shown in FIG. 1, in a secondary battery 10 as a power storage device, an electrode assembly 12 and an electrolytic solution (not shown) are accommodated in a case 11. The case 11 includes a bottomed square cylindrical case main body 13 and a rectangular flat lid 14 that closes an opening 13 a for inserting the electrode assembly 12 into the case main body 13. Both the case body 13 and the lid body 14 are made of metal (for example, made of stainless steel or aluminum). The secondary battery 10 is a prismatic battery and is a lithium ion battery.

  As shown in FIG. 2, the electrode assembly 12 includes a long rectangular sheet-shaped separator 23 between a long rectangular sheet-shaped positive electrode 24 and a long rectangular sheet-shaped negative electrode 25. It is the structure wound around the winding axis | shaft L in the shape of a spiral. The separator 23 is made of an insulating resin (for example, polyethylene). The electrode assembly 12 is wound in a state where the positive electrode 24 is an outer layer of the negative electrode 25.

  The positive electrode 24 includes a long rectangular sheet-like positive electrode metal foil 24a and a positive electrode active material layer 24b provided in a strip shape on both surfaces of the positive electrode metal foil 24a. The positive electrode 24 has a positive width uncoated portion 24d having no positive electrode active material layer 24b with a constant width along a first side 24c extending in the longitudinal direction.

  As shown in FIG. 4, in the positive electrode 24, the length of the positive electrode active material layer 24 b in the longitudinal direction is set to a length that allows at least one round of the electrode assembly 12 around the winding axis L. In the positive electrode 24, the start end S1 of the positive electrode active material layer 24b is located at one end in the longitudinal direction where winding starts, and the end S2 of the positive electrode active material layer 24b is located midway along the longitudinal direction of the positive electrode 24. . The positive electrode 24 has a positive electrode metal layer 24f as a metal layer composed of only the positive electrode metal foil 24a before the terminal end S2 of the positive electrode active material layer 24b. The length of the positive electrode metal layer 24f from the terminal end S2 of the positive electrode active material layer 24b to the other end in the longitudinal direction of the positive electrode 24 is set to a length that can cover the entire exposed positive electrode active material layer 24b. ing.

  As shown in FIG. 2, the negative electrode 25 includes a long rectangular sheet-like negative electrode metal foil 25a and a negative electrode active material layer 25b provided in a strip shape on both surfaces of the negative electrode metal foil 25a. The negative electrode 25 has a negative electrode uncoated portion 25d having a constant width, along which the first side 25c extending in the longitudinal direction is not provided with the negative electrode active material layer 25b.

  As shown in FIG. 4, in the negative electrode 25, the length of the negative electrode active material layer 25 b in the longitudinal direction is set to a length that allows at least one round of the electrode assembly 12 around the winding axis L. The negative electrode 25 has a start end T1 of the negative electrode active material layer 25b at one end in the longitudinal direction at which winding starts, and the start end T1 of the negative electrode active material layer 25b is in the stacking direction of the electrode assembly 12 in the positive electrode active material layer 24b. Is at the same position as the starting edge S1. In addition, the end T2 of the negative electrode active material layer 25b is located in the middle of the negative electrode 25 in the longitudinal direction, and the end T2 of the negative electrode active material layer 25b is in the stacking direction of the electrode assembly 12 with respect to the positive electrode active material layer 24b. It is at the same position as the end T2. The negative electrode 25 has a negative electrode metal layer 25f composed of only the negative electrode metal foil 25a before the end T2 of the negative electrode active material layer 25b. The length of the negative electrode metal layer 25f from the end T2 of the negative electrode active material layer 25b to the other longitudinal end of the negative electrode 25 is set to a length that can cover the exposed positive electrode active material layer 24b over the entire circumference. ing.

  As shown in FIG. 3, in the electrode assembly 12, the positive electrode uncoated portion 24 d of the positive electrode 24 and the portion on the first side 24 c side in the positive metal layer 24 f are the first axial direction in which the winding axis L extends. It is located at the end 12a. The electrode assembly 12 includes a positive electrode connection portion 28 in which the positive electrode uncoated portion 24d and the positive electrode metal layer 24f are collected at the first end portion 12a. The positive electrode connection portion 28 includes the positive electrode uncoated portion 24d and the positive electrode metal. The layer 24f is layered with no separator 23 interposed therebetween.

  In the electrode assembly 12, the negative electrode uncoated portion 25 d of the negative electrode 25 and the first side 25 c side portion of the negative electrode metal layer 25 f are positioned at the second end portion 12 b in the axial direction of the electrode assembly 12. ing. The electrode assembly 12 includes a negative electrode connection portion 29 in which the negative electrode uncoated portion 25d and the negative electrode metal layer 25f are collected at the second end portion 12b. The negative electrode connection portion 29 includes the negative electrode uncoated portion 25d and the negative electrode metal. The layer 25f is layered with no separator 23 interposed therebetween.

  As shown in FIG. 4, in the electrode assembly 12, the positive electrode metal layer 24 f constitutes the outermost layer, and the negative electrode metal layer 25 f is opposed to the stacking direction via the separator 23 on the inner peripheral side of the positive electrode metal layer 24 f. Are arranged. In the electrode assembly 12, the positive electrode metal layer 24f covers the entire surface of the positive electrode active material layer 24b through the separator 23 and the negative electrode metal layer 25f over the entire circumference. The positive electrode metal layer 24 f does not cover the negative electrode connection portion 29, and the positive electrode metal layer 24 f covers from the first end 12 a to the negative electrode connection portion 29 along the axial direction of the electrode assembly 12. .

  As shown in FIG. 3, the tip end portion of the positive electrode conductive member 17 is electrically connected to the positive electrode connection portion 28 of the electrode assembly 12. The positive electrode conductive member 17 is formed by bending a substantially rectangular flat plate made of metal (aluminum in this embodiment) by, for example, pressing. The positive electrode conductive member 17 includes a rectangular flat plate-like connection portion 17 a that is electrically connected to the positive electrode connection portion 28. Further, the positive electrode conductive member 17 includes a conductive portion 17 b that is connected to the connection portion 17 a and extends along the surface of the first end portion 12 a of the electrode assembly 12. Further, the positive electrode conductive member 17 includes a terminal connection portion 17 c that is connected to the conductive portion 17 b, extends along the axial direction of the electrode assembly 12, and is disposed to face the peripheral surface of the electrode assembly 12.

  A positive electrode terminal 15 is connected to the terminal connection portion 17c. The positive electrode terminal 15 includes a base portion 15a welded to the terminal connection portion 17c and a shaft portion 15b provided upright from the base portion 15a. A ring-shaped insulating member 19 for insulating the positive terminal 15 from the case 11 is attached to the shaft portion 15 b of the positive terminal 15. Further, a seal member 20 is sandwiched between the inner surface of the lid body 14 and a surface facing the inner surface of the lid body 14 in the base portion 15 a, and the penetrating portion of the shaft portion 15 b in the lid body 14 is hermetically sealed by the seal member 20. Is sealed.

  A current interrupt device 30 is provided in the terminal connection portion 17c. The current interrupt device 30 interrupts the current flowing through the positive electrode terminal 15 when the pressure in the case 11 exceeds a threshold value. The current interrupt device 30 is electrically connected to the terminal connection portion 17c and the positive terminal 15 and is a positive electrode. A pressure receiving portion (not shown) of the current interrupt device 30 faces the case 11 and can detect the pressure in the case 11. Further, the current interrupt device 30 is disposed to face the outer surface of the positive electrode metal layer 24f of the electrode assembly 12, and is separated from the positive electrode metal layer 24f to the lid body 14 side.

  The tip of the negative electrode conductive member 18 is electrically connected to the negative electrode connection portion 29 of the electrode assembly 12. The negative electrode conductive member 18 is formed by bending a substantially rectangular flat plate made of metal (copper in this embodiment) by, for example, pressing. The negative electrode conductive member 18 includes a rectangular flat plate-shaped connection portion 18 a that is electrically connected to the negative electrode connection portion 29. Further, the negative electrode conductive member 18 includes a conductive portion 18 b that is connected to the connection portion 18 a and extends along the surface of the second end portion 12 b of the electrode assembly 12. Further, the negative electrode conductive member 18 includes a terminal connection portion 18 c that is connected to the conductive portion 18 b, extends along the axial direction of the electrode assembly 12, and is disposed to face the peripheral surface of the electrode assembly 12.

  The negative terminal 16 is connected to the terminal connection portion 18c. The negative electrode terminal 16 includes a base portion 16a that is welded to the terminal connection portion 18c, and a shaft portion 16b that is erected from the base portion 16a. A ring-shaped insulating member 19 for insulating the negative electrode terminal 16 from the case 11 is attached to the shaft portion 16 b of the negative electrode terminal 16. Further, a seal member 21 is sandwiched between the inner surface of the lid body 14 and a surface facing the inner surface of the lid body 14 in the base portion 16a, and the penetrating portion of the shaft portion 16b in the lid body 14 is hermetically sealed by the seal member 21. Is sealed.

Next, the operation of the secondary battery 10 will be described.
The outermost layer of the electrode assembly 12 is constituted by a positive electrode metal layer 24f extending from the positive electrode 24, and a current interrupt device 30 is disposed so as to face the positive electrode metal layer 24f. For this reason, even if the electric current interruption apparatus 30 and the positive electrode metal layer 24f contact, a short circuit is suppressed.

According to the above embodiment, the following effects can be obtained.
(1) The outermost layer of the electrode assembly 12 was composed of the positive electrode metal layer 24f. For this reason, in the secondary battery 10 in which the current interrupt device 30 is disposed opposite to the peripheral surface of the electrode assembly 12, no short circuit occurs even if the current interrupt device 30 contacts the electrode assembly 12.

  (2) The outermost layer of the electrode assembly 12 was composed of a positive electrode metal layer 24f without the positive electrode active material layer 24b. For this reason, even if the positive electrode metal layer 24f is provided to suppress a short circuit with the current interrupt device 30, the positive electrode active material layer 24b does not face the negative electrode active material layer 25b because there is no positive electrode active material layer 24b. Precipitation of metallic lithium is suppressed.

  (3) Since the outermost layer of the electrode assembly 12 is the positive electrode metal layer 24f, the current interrupt device 30 can be installed on the lid body 14, and the secondary battery 10 has only one wall portion requiring airtightness. It can be. For this reason, the wall part which should be changed when airtightness falls can be minimized while suppressing the short circuit with the electrode assembly 12 and the electric current interruption apparatus 30. FIG.

  (4) Since the outermost layer of the electrode assembly 12 is the positive electrode metal layer 24f, the current interrupt device 30 can be installed on the lid body 14. For this reason, for example, compared to the case where the current interrupt device 30 is installed on the side wall of the case body 13 and the positive electrode terminal 15 and the negative electrode terminal 16 are installed on the lid body 14, the dead space in the case 11 is reduced, and the case 11 can increase the space in which the electrode assembly 12 can be disposed. Therefore, the energy density of the secondary battery 10 can be increased.

  (5) In the positive electrode 24, the positive electrode metal foil 24a was extended before the terminal S2 of the positive electrode active material layer 24b, and the positive electrode metal layer 24f was formed by the positive electrode metal foil 24a. For this reason, the secondary battery 10 which suppressed the short circuit with the electric current interruption apparatus 30 using the positive electrode 24 can be manufactured easily.

  (6) The negative electrode metal layer 25f was opposed to the positive electrode metal layer 24f with the separator 23 interposed therebetween. For this reason, the positive electrode metal layer 24f and the negative electrode metal layer 25f can function as safety electrodes, and if a foreign object is stuck in the secondary battery 10, the positive electrode metal layer 24f and the negative electrode metal layer 25f are internally short-circuited. The energy of the secondary battery 10 can be released.

In addition, you may change the said embodiment as follows.
In the embodiment, the negative electrode metal layer 25f is provided on the negative electrode 25 so as to face the positive electrode metal layer 24f, but the negative electrode metal layer 25f is not provided on the negative electrode 25, and the negative electrode active layer is provided so as to face the positive electrode metal layer 24f. The material layer 25b may be extended, and the negative electrode active material layer 25b may be opposed to the positive electrode metal layer 24f.

  In the embodiment, the negative electrode metal layer 25f opposite to the positive electrode metal layer 24f is provided. However, the negative electrode 25 is extended to the end T2 of the negative electrode active material layer 25b, the negative electrode metal layer 25f is eliminated, and only the positive electrode metal layer 24f is used. Good.

  In the embodiment, the electrode assembly 12 is wound in a state where the positive electrode 24 is an outer layer of the negative electrode 25, but the electrode assembly 12 is a state in which the negative electrode 25 is an outer layer of the positive electrode 24. It may be wound. Also in this case, the positive electrode metal foil 24a is extended, or a metal foil separate from the positive electrode metal foil 24a of the positive electrode 24 is joined to the positive electrode 24 to form the positive metal layer 24f. 24f covers the negative electrode 25 to form the outermost layer of the electrode assembly 12.

The positive metal layer may be formed by bonding a metal foil that is separate from the positive electrode metal foil 24 a of the positive electrode 24.
In the embodiment, the lid 14 is a wall, but the side wall or bottom wall of the case body 13 may be a wall.

The positive electrode metal layer 24f may be wound so as to be located only in a portion of the outermost layer of the electrode assembly 12 that faces the current interrupt device 30.
In the embodiment, the positive electrode 24 has the positive electrode active material layer 24b on both sides of the positive electrode metal foil 24a, but may have the positive electrode active material layer 24b only on one side of the positive electrode metal foil 24a. . Similarly, the negative electrode 25 has the negative electrode active material layer 25b on both surfaces of the negative electrode metal foil 25a, but may have the negative electrode active material layer 25b only on one surface of the negative electrode metal foil 25a.

  In the embodiment, the secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer 24b and the negative electrode active material layer 25b through the separator 23 and the electrolytic solution, and charge is transferred.

The power storage device may be applied to other power storage devices such as an electric double layer capacitor.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) A power storage device having a metal layer electrically connected to the negative electrode inside the metal layer.

  (B) The power storage device, wherein the metal layer electrically connected to the negative electrode is a negative electrode metal foil of the negative electrode.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as an electrical storage device, 11 ... Case, 12 ... Electrode assembly, 14 ... Lid as wall part, 15 ... Positive electrode terminal, 16 ... Negative electrode terminal, 24 ... Positive electrode, 24a ... As metal foil Metal foil for positive electrode, 24b ... positive electrode active material layer as active material layer, 24f ... positive electrode metal layer as metal layer, 25 ... negative electrode, 25a ... metal foil for negative electrode as metal foil, 25b ... as active material layer Negative electrode active material layer, 30 ... current interrupting device.

Claims (3)

An electrode assembly wound with a positive electrode and a negative electrode having an active material layer on at least one side of a long metal foil in an insulated state;
A case containing the electrode assembly;
A positive electrode terminal electrically connected to the positive electrode;
A negative electrode terminal electrically connected to the negative electrode;
A current interrupting device electrically connected to the positive terminal,
The current interrupting device, the positive electrode terminal and the negative electrode terminal are power storage devices arranged in a state where airtightness is ensured in one wall portion of the case,
A metal layer wound in a state constituting the outermost layer of the electrode assembly and electrically connected to the positive electrode;
The current interrupting device is a power storage device installed opposite to the outer surface of the metal layer.   The power storage device according to claim 1, wherein the metal layer is a metal foil for a positive electrode included in the positive electrode.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.