JP2013206815A - Exterior container, and power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively discharge gas through a safety valve.SOLUTION: A lid 68 has a safety valve 70. In the safety valve 70, a first recess 76 is formed on an inner side of the lid 68, and a second recess 78 is formed on an outer side of the lid 68 corresponding to the first recess 76 of the lid 68. The safety valve 70 is formed between the first recess 76 and the second recess 78. According to the present invention, cross sectional areas of the first recess 76 and the second recess 78 on a cross section vertical to a plane direction of the lid 68 get gradually smaller toward the safety valve 70. Therefore, a pressure of gas flowing to the safety valve 70 from an inner side of the lid 68 is gradually increased when passing through the first recess 76, and a pressure of gas flowing to an outer side of the lid 68 from the safety valve 70 is gradually decreased when passing through the second recess 78. Thus, pressure reduction when the gas passing through the first recess 76 is emitted to the outer side of the lid 68 can be restrained, so as to effectively exhaust the gas.

Description

  The present invention relates to a structure of a safety valve for a power storage element.

  Conventionally, a battery such as a secondary battery has been used. The battery includes a power generation element and an electrolytic solution housed in a metal outer container such as aluminum (for example, cited document 1). In the case of a battery, the pressure inside the unit cell rises due to heat generation due to charging / discharging and changes in the environmental temperature, and the outer container is damaged, and the broken pieces of the outer container are scattered around the unit etc. In order to prevent the device from being damaged, a safety valve is provided that breaks and discharges gas when the internal pressure in the battery exceeds a predetermined value.

JP 2004-319308 A

  Since the safety valve is formed for the above-mentioned purpose, it is preferable that the gas discharge amount of the safety valve is large. However, in recent years, the range in which a safety valve can be formed has been reduced due to a demand for downsizing of a single cell, and it is desired that the safety valve effectively discharges gas in a small area. As in the prior art, by narrowing the shape of the gas discharge port from the inside to the outside of the unit cell, the pressure of the gas passing through the gas discharge port can be gradually increased. Can be smoothly moved to the gas flow port. However, in the prior art, when the gas that has passed through the gas flow port goes out of the unit cell, a large pressure drop occurs, resulting in a large fluid resistance to the gas, and the gas cannot be effectively discharged. .

  It is an object of the present invention to provide a technique for discharging gas through a safety valve.

  The exterior container of the present invention is an exterior container for a power storage element, wherein a first recess is formed on an inner wall of the exterior container, and an outer wall of the exterior container corresponding to the first recess of the exterior container is formed. A safety valve which is formed with a second recess, and is ruptured and discharges gas when the internal pressure of the outer container exceeds a predetermined value between the first recess and the second recess; The cross-sectional areas of the first concave portion and the second concave portion in the cross section perpendicular to the surface direction of the outer packaging container in the portion where is formed are reduced toward the safety valve.

  According to this outer container, the pressure of the gas flowing into the safety valve from the inside of the outer container gradually increases when passing through the first recess, and the pressure of the gas flowing out of the outer container from the safety valve passes through the second recess. Gradually descends. Therefore, the pressure drop that occurs when the gas that has passed through the second recess is released to the outside of the external container can be suppressed, and the gas can be effectively discharged by suppressing the fluid resistance generated in the gas. Can do.

  In the outer container, in the cross section including the safety valve, the cross-sectional shape of the first recess is displaced in the first direction from the inner wall to the outer wall of the outer container as it goes from the peripheral region of the safety valve to the safety valve. The cross-sectional shape of the second recess may be displaced in the second direction from the outer wall to the inner wall of the outer container as it goes from the peripheral region of the safety valve to the safety valve. According to this exterior container, the gas inside the exterior container can be smoothly discharged to the outside of the exterior container using the first recess and the second recess, and the gas fluid resistance can be suppressed.

  In the said exterior container, the cross-sectional shape of the said 1st recessed part and the said 2nd recessed part is good also as a structure which is a convex curve outside. According to this exterior container, the first recess and the inner wall around the first recess can be smoothly connected, and the fluid resistance generated at the connection portion can be suppressed. Further, the second recess and the outer wall around the second recess can be connected smoothly, and the fluid resistance generated at the connection portion can be suppressed.

  In the outer container, in the direction along the outer container of the portion where the safety valve is formed, the first range in which the bottom of the first recess is formed is the second range in which the bottom of the second recess is formed. The first range may be narrower than the second range.

  In this exterior container, in the direction along the exterior container, a part of the second range is provided outside the first range, and a part of the second recess is provided outside the safety valve. Therefore, when the safety valve breaks and the fragment of the broken safety valve moves to the outer peripheral portion of the safety valve, the fragment can be accommodated in the second recess. According to this outer container, by accommodating the fragment of the safety valve in the second recess, it is suppressed that the fragment is subsequently exposed to gas or the like discharged from the inside of the electric storage element and separated from the peripheral region, It is possible to suppress the fragments of the safety valve from being scattered to surrounding devices.

  The present invention is also embodied in a power storage device including the above-described outer container. According to this power storage element, the gas accumulated inside the power storage element can be efficiently discharged.

  According to the present invention, gas can be efficiently discharged through a safety valve.

Single cell development Sectional drawing of the safety valve of Embodiment 1 Sectional drawing of the safety valve of Embodiment 2 Sectional drawing of the safety valve of other embodiment Sectional drawing of the safety valve of other embodiment

<Embodiment 1>
Hereinafter, Embodiment 1 will be described with reference to FIGS.
1. Configuration of Single Cell FIG. 1 is a perspective view of a single cell 14 in the present embodiment. The unit cell 14 is a secondary battery that can be repeatedly charged and discharged, and more specifically a lithium ion battery. The plurality of unit cells 14 of the present embodiment are connected to each other by a bus bar, which is a conductive plate member, and is mounted on, for example, an electric vehicle or a hybrid vehicle, and supplies power to a power source that operates with electric energy. . The unit cell 14 is an example of a power storage element.

  As shown in FIG. 1, the unit cell 14 includes an electrode unit 20, a power generation element 50, a clip 60, and a case 62. Hereinafter, the vertical direction in FIG. 1 is defined as the vertical direction of the unit cell 14, and the direction perpendicular to the wide side surface of the side surfaces of the case 62 is the front-rear direction of the single cell 14 and the side surface on the narrow area side. The direction will be described as the left-right direction of the unit cell 14. The upper side is an example of the first direction, and the lower side is an example of the second direction.

  The case 62 is made of metal such as aluminum and has a square shape. The case 62 is formed in an upper open type with the upper end open, and the case 62 houses the power generation element 50 having a flat shape and is filled with an electrolytic solution. The upper end opening of the case 62 is closed by a lid body 68 that is a rectangular plate member constituting the electrode unit 20. The case 62 and the lid body 68 are an example of an exterior container.

  In the electrode unit 20, a pair of a positive electrode terminal 22 and a negative electrode terminal 24 are arranged on the upper surface of the lid 68 side by side in the left-right direction. In addition, a pair of current collectors 28 </ b> A and 28 </ b> B that are electrically connected to the electrode terminals 22 and 24 and extend downward from the lower surface of the lid 68 are provided. Each of the current collectors 28A and 28B is made of a metal plate having a sufficient thickness so as to obtain a large current capacity. The positive electrode current collector 28A is made of, for example, an aluminum alloy plate, and the negative electrode current collector 28B is For example, it consists of a copper plate alloy plate. In addition, the lid 68 is provided with a safety valve 70 which will be described in detail later.

  The power generation element 50 has a cylindrical shape wound in a flat shape with a separator (not shown) sandwiched between the positive electrode plate 52 and the negative electrode plate 54. The positive electrode plate 52 and the negative electrode plate 54 each have a strip shape in which the winding direction is the longitudinal direction in the unwound state. The positive electrode plate 52 has a positive electrode active material layer formed on the surface of an aluminum foil having a band shape, and the aluminum foil is exposed at one edge extending in the longitudinal direction without forming the positive electrode active material layer. A positive electrode current collector foil 52A is formed. Further, the negative electrode plate 54 has a negative electrode active material layer formed on the surface of a strip-like copper foil, and the negative electrode active material layer is not formed on one edge extending in the longitudinal direction of the copper foil. An exposed negative electrode current collector foil 54A is formed.

  In the positive electrode plate 52 and the negative electrode plate 54, the negative electrode current collector foil 54A is disposed on one end side with respect to the separator and the negative electrode plate 54, and the positive electrode current collector foil 52A is disposed on the other end side with respect to the separator and the positive electrode plate 52. It is rolled up in layers. Accordingly, only the positive electrode current collector foil 52A is laminated and protruded on one end side of the power generation element 50, and only the negative electrode current collector foil 54A is laminated and protruded on the other end side.

  The positive electrode current collector foil 52A is connected to the positive electrode current collector 28A at a side surface portion (see a two-dot chain line in FIG. 1) extending linearly in the vertical direction. The negative electrode current collector foil 54A is connected to the negative electrode current collector 28B at a side surface portion (see a two-dot chain line in FIG. 1) extending linearly in the vertical direction.

  The current collectors 28 </ b> A and 28 </ b> B and the current collector foils 52 </ b> A and 54 </ b> A are connected by ultrasonic welding while being sandwiched between the clips 60. The clip 60 is made of a material having a resistance value equivalent to the material of the current collectors 28A and 28B and the current collector foils 52A and 54A to be welded, the positive clip 60A is made of an aluminum alloy, and the negative clip 60B is Made of copper alloy.

2. Configuration of Safety Valve A non-restorable safety valve 70 is provided at the center of the lid body 68. The non-restorable safety valve 70 is broken to release the gas in the case 62 when the pressure in the case 62 exceeds a predetermined value. The safety valve 70 is a thin film made of a metal such as stainless steel and has a circular shape. In the safety valve 70, a safety valve member 72 including the safety valve 70 is formed separately from the lid body 68, and a peripheral portion 71 of the safety valve member 72 is attached to the lid body 68 by laser welding or the like. In the following description, the peripheral portion 71 of the safety valve member 72 and the lid body 68 connected to the peripheral portion 71 are collectively referred to as a peripheral region 74 of the safety valve 70.

  FIG. 2 is a sectional view of the safety valve 70 taken along the line II-II in FIG. As shown in FIG. 2, the safety valve 70 is formed thinner than the peripheral region 74, and the safety valve 70 has a first recess 76 that is recessed from the peripheral region 74 on the inner side of the lid 68. . The first recess 76 also serves as a flow path through which the gas in the case 62 moves to the safety valve 70 when the pressure in the case 62 becomes a predetermined value or more.

  On the other hand, on the outer side of the lid body 68, a protruding portion 66 that protrudes upward is formed in the peripheral region 74. In the safety valve 70, a second recess 78 that is recessed from the peripheral region 74 including the raised portion 66 is formed on the outside of the lid 68. The second recess 78 also serves as a flow path through which the gas that has passed through the safety valve 70 moves out of the case 62 when the pressure in the case 62 becomes a predetermined value or more. It can be said that the safety valve 70 is a portion remaining between the first recess 76 and the second recess 78 provided in the lid body 68 in terms of shape.

  The first recess 76 has a circular cross section perpendicular to the up-down direction, the diameter decreases toward the safety valve 70, and the cross-sectional area is the smallest on the inner wall 70 </ b> A of the safety valve 70 that contacts the bottom 76 </ b> A of the first recess 76. . In the cross section shown in FIG. 2, the 1st recessed part 76 becomes a convex circular arc on the outer side. That is, the first recess 76 is gradually displaced upward from the inner wall 74A of the peripheral region 74 toward the inner wall 70A of the safety valve 70, and gradually gradually from the inner wall 74A of the peripheral region 74 to the inner wall 70A of the safety valve 70. Flow area is shrinking.

  As shown in FIG. 2, the first recess 76 is smoothly connected to the inner wall 74 </ b> A of the peripheral region 74. On the other hand, the first recess 76 is connected to the inner wall 70 </ b> A of the safety valve 70 from a substantially orthogonal direction and is connected at a connection point 80.

  The second concave portion 78 has a circular cross section perpendicular to the vertical direction, the diameter of the second concave portion 78 decreases toward the safety valve 70, and the sectional area of the outer wall 70B of the safety valve 70 corresponding to the bottom 78A of the second concave portion 78 is the smallest. . In the cross section shown in FIG. 2, the second recess 78 is an outwardly convex arc. That is, the second recessed portion 78 gradually moves upward as it goes from the outer wall 70B of the safety valve 70 to the outer wall 74B of the peripheral region 74, and gradually increases as it goes from the outer wall 70B of the safety valve 70 to the outer wall 74B of the peripheral region 74. The flow area is expanding.

  As shown in FIG. 2, the second recess 78 is smoothly connected to the outer wall 74 </ b> B of the peripheral region 74. On the other hand, the second recess 78 is connected to the outer wall 70 </ b> B of the safety valve 70 from a substantially orthogonal direction and is connected at a connection point 82.

  In the present embodiment, as shown in FIG. 3, the connection point 80 and the connection point 82 are arranged at the same position in the left-right direction. That is, the inner wall 70A and the outer wall 70B of the safety valve 70 are formed to have the same shape. As shown in FIG. 2, the radius of curvature in the cross section of the first concave portion 76 is larger than the radius of curvature in the cross section of the second concave portion 78, and the first concave portion 76 is formed to be wider than the second concave portion 78. ing.

3. Advantages of the Present Invention (1) In the unit cell 14 of the present embodiment, the area of the cross-sectional circle of the first recess 76 is reduced and the flow area is reduced from the inner wall 74A of the peripheral region 74 toward the inner wall 70A of the safety valve 70. . Further, the area of the cross-sectional circle of the second recess 78 increases from the outer wall 70B of the safety valve 70 toward the outer wall 74B of the peripheral region 74, and the flow area increases. Therefore, the gas discharged from the inside of the case 62 through the first concave portion 76 and the second concave portion 78 gradually increases in pressure when passing through the first concave portion 76 and passes through the second concave portion 78. At that time, the pressure gradually decreases. Therefore, when the gas that has passed through the first recess 76 passes through the safety valve 70, it is possible to prevent the pressure from rapidly increasing. Further, when the gas that has passed through the second recess 78 is released to the outside of the case 62, it is possible to suppress a sudden pressure drop. According to this single cell 14, it is possible to suppress the fluid resistance caused by the pressure change of the gas passing through the safety valve 70, and the gas can be effectively discharged using the safety valve 70.

(2) In the unit cell 14 of the present embodiment, the cross-sectional shape of the first recess 76 is gradually displaced upward from the inner wall 74A of the peripheral region 74 toward the inner wall 70A of the safety valve 70, and the first recess The gas inside the case 62 can be smoothly moved to the safety valve 70 by using 76. Further, the cross-sectional shape of the second recess 78 is gradually displaced upward from the outer wall 70B of the safety valve 70 toward the outer wall 74B of the peripheral region 74, and the second recess 78 is used to pass through the safety valve 70. The gas can be smoothly moved to the outside of the case 62.

(3) In the unit cell 14 of this embodiment, since the cross-sectional shapes of the first recess 76 and the second recess 78 are outwardly convex arcs, the first recess 76 and the inner wall 74A of the peripheral region 74 Can be connected smoothly, and the fluid resistance generated at this connecting portion can be suppressed. Moreover, the 2nd recessed part 78 and the outer wall 74B of the peripheral region 74 can be connected smoothly, and the fluid resistance which generate | occur | produces in this connection part can be suppressed.

<Embodiment 2>
A second embodiment will be described with reference to FIG. As shown in FIG. 3, the unit cell 14 of the present embodiment is different from that of Embodiment 1 in that the bottom 78A of the second recess 78 is formed wider than the outer wall 70B of the safety valve 70 in a cross section perpendicular to the vertical direction. And different. In the following description, the same description as that of the first embodiment will not be repeated.

  In the present embodiment, the bottom 76A of the first recess 76 is equal to the inner wall 70A of the safety valve 70, and the bottom 78A of the second recess 78 is formed wider than the outer wall 70B of the safety valve 70. That is, the range 84 where the bottom 76A is formed is included in the range 86 where the bottom 76A is formed, and the range 84 is narrower than the range 86. In addition to the range 84, the range 86 includes a range in which a valve outer region 88 provided around the bottom 76A (that is, the inner wall 70A and the outer wall 70B of the safety valve 70) is formed. The range 84 is an example of a first range, and the range 86 is an example of a second range.

Advantageous Effects of the Invention In the unit cell 14 of the present embodiment, the outside valve region 88 is provided outside the safety valve 70, and the second recess 78 is also provided outside the safety valve 70. Therefore, fragments of the safety valve 70 that are broken when the gas is discharged from the inside of the case 62 to the outside through the safety valve 70 can be retained in the second recess 78 by the valve outer region 88. Thereby, it is possible to suppress the fragments of the safety valve 70 from being scattered to surrounding devices.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above embodiment, the unit cell 14 which is a secondary battery is shown as an example of the power storage element. However, the present invention is not limited thereto, and the capacitor with an electrochemical phenomenon is acceptable as long as the power storage element may be a primary battery. It may be. Moreover, the use of the unit cell 14 and the structure of the electrode unit of the unit cell 14 are not particularly limited.

(2) In the above-described embodiment, as an example of the cross-sectional shape of the first recess 76 and the second recess 78, a convex arc is shown on the outside. However, the present invention is not limited thereto, and may be elliptical or hyperbolic. . Moreover, it does not need to be a curve, and as shown in FIG. 4, it may be a C-plane formed by a straight line, or may be stepped.

(3) In the above embodiment, the example in which the safety valve member 72 is formed separately from the lid 68 has been described. However, the embodiment is not limited thereto, and the safety valve member 72 may be integrally formed with the lid 68. Further, the outer shape of the safety valve 70 is not limited to a circle, and the material thereof is not limited to the embodiment.

(4) In the above embodiment, the example in which the raised portion 66 is formed in the peripheral region 74 has been described. However, the present invention is not limited to this, and the raised portion 66 is not formed as shown in FIG. May be. Further, when the raised portion 66 is greatly raised upward, the safety valve 70 may be arranged above the lid 68 as shown by an arrow 90 in FIG.

14: Cell, 62: Case, 66: Raised portion, 68: Lid, 70: Safety valve, 70A: Inner wall of safety valve, 70B: Outer wall of safety valve, 74: Peripheral region, 74A: Inner wall of peripheral region, 74B: Peripheral Outer wall of region, 76: first recess, 78: second recess

Claims (5)

An exterior container for a storage element,
A first recess is formed in the inner wall of the outer container, and a second recess is formed in an outer wall of the outer container corresponding to the first recess of the outer container. The first recess and the second A safety valve that breaks and discharges gas when the internal pressure of the outer container is equal to or greater than a predetermined value between the recess and the recess,
The exterior container in which the cross-sectional areas of the first recess and the second recess in a cross section perpendicular to the surface direction of the exterior container in a portion where the safety valve is formed are reduced toward the safety valve. The exterior container according to claim 1,
In the cross section including the safety valve, the cross-sectional shape of the first recess is displaced in the first direction from the inner wall of the exterior container toward the outer wall as it goes from the peripheral region of the safety valve to the safety valve, and the second recess The cross sectional shape of the outer container is displaced in a second direction from the outer wall to the inner wall of the outer container as it goes from the peripheral region of the safety valve to the safety valve. The exterior container according to claim 2,
The cross-sectional shape of the said 1st recessed part and the said 2nd recessed part is an exterior container which is an outward convex curve. An exterior container according to any one of claims 1 to 3,
The first range in which the bottom of the first recess is formed in the direction along the outer container of the portion where the safety valve is formed is included in the second range in which the bottom of the second recess is formed, The first range is an exterior container that is narrower than the second range.   The electrical storage element provided with the exterior container as described in any one of Claims 1 thru | or 4.

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