JP2015164111A - power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of efficiently releasing pressure at a time of pressure release while protecting a pressure release valve and suppressing scattering of foreign matter.SOLUTION: A secondary battery 10 includes a pressure release valve 20 for releasing pressure inside a case 11 to an outside of the case 11. The secondary battery 10 includes: a first thin-film-shaped protective member 26 for covering an entire outer surface 21a of a valve body 21 at the pressure release valve 20; and a second metal-net-shaped protective member 27 for covering the valve body 21 of the pressure release valve 20 from the outer surface 21a through the first protective member 26.

Description

  The present invention relates to a power storage device having a pressure release valve that releases pressure inside a case to the outside of the case.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. The secondary battery has an electrode assembly in which a negative electrode obtained by applying a negative electrode active material to a metal foil and a positive electrode obtained by applying a positive electrode active material to a metal foil are insulated with a separator and laminated in layers. The case of the secondary battery contains an electrode assembly and an electrolytic solution, and a pressure release valve for releasing the pressure inside the case to the outside of the case is provided on the wall of the case (for example, Patent Documents). 1).

  As shown in FIG. 7, a battery body 80 made of a lithium ion battery of Patent Document 1 includes a case 81 having an opening and a sealing member 82 that closes the opening of the case 81. An electrode group is accommodated. The sealing member 82 ruptures before the case 81 is destroyed when a pressure increase in the case 81 occurs with the joint portion 82a to which the end of the positive electrode lead 84 is welded, and the pressure in the case 81 is reduced. It has a pressure release valve 82b that opens to the outside. The sealing member 82 includes a holding portion 82c that holds the pressure release valve 82b, a current limiting element 82d that is sandwiched between the pressure release valve 82b and the holding portion 82c, and prevents a current exceeding a specified value from flowing, and a positive electrode terminal 82e. And having. Each element of the sealing member 82 has a vent except for the pressure release valve 82b. The vent hole of the positive electrode terminal 82 e constitutes an exhaust port 85 through which gas is ejected when the pressure release valve 82 b is cleaved due to an increase in the internal pressure of the case 81.

  The positive electrode terminal 82e is provided with a mesh part 83 made of non-flammable, thermally conductive and conductive wire, for example, SUS, so as to face the exhaust port 85. In the case of the lithium ion battery, even if it is ignited due to a malfunction in the case 81, the heat of the flame ejected from the exhaust port 85 can be extinguished by the mesh portion 83.

JP 2009-2111909 A

  By the way, the pressure release valve of the secondary battery may be divided into a plurality of valve pieces when it is cleaved by receiving pressure in the case. Further, when the pressure is released, the contents of the case may pop out through the released pressure release valve. It is not preferable that the divided valve pieces and contents are scattered from the case. For example, the scattered valve pieces cause damage to other peripheral parts due to collision with other peripheral parts, and the scattered valve pieces and contents adhere to the bus bar connecting the terminals of the secondary battery and are short-circuited. Make factors.

  In the lithium ion battery of Patent Document 1, the mesh part 83 can suppress scattering of a relatively large foreign object such as a divided valve piece from the case. However, relatively small foreign matters such as dust are floating around the lithium ion battery. The comparatively small foreign matter passes through the mesh portion 83, and the small foreign matter that has passed through the mesh portion 83 adheres to the outer surface of the pressure release valve 82b or damages the pressure release valve 82b. Therefore, it is conceivable to make the holes of the mesh portion 83 small so that small foreign substances cannot pass through. However, in this case, the mesh portion 83 itself hinders the pressure release when the pressure is released, and the pressure can be released efficiently. It will disappear.

  An object of the present invention is to provide a power storage device that can efficiently release pressure when pressure is released and can suppress scattering of foreign matters while protecting the pressure release valve.

  A power storage device for solving the above problems is a power storage device having a pressure release valve for releasing the pressure in the case to the outside of the case, a thin film-like first protective member covering the entire outer surface of the pressure release valve, And a porous second protective member that covers the pressure relief valve from the outer surface via the first protective member.

  According to this, for example, when the power storage device is used in an environment where air is introduced from the outside for air cooling of the power storage device, foreign matter is floating around the power storage device. A relatively large foreign object cannot pass through the hole of the second protection member, and the pressure protection valve can be protected by the second protection member, and the first protection member can also be protected. Although relatively small foreign matter such as dust passes through the hole of the second protective member, the first protective member can protect the pressure relief valve from foreign matter, and the foreign matter may adhere to the outer surface of the pressure relief valve, Damage to the pressure release valve can be suppressed.

  If the pressure in the case reaches the open pressure and the pressure release valve is cleaved, even if a part of the valve body is divided, the second protective member receives a part of the valve body, and a part of the valve body Can be prevented from scattering. Moreover, it can suppress that the content which protruded from the inside of a case is scattered by the 2nd protection member. And since the 2nd protection member is porous, the 2nd protection member does not become the hindrance of pressure release, and it releases pressure efficiently, suppressing scattering of the contents and a part of valve body. Can do.

Moreover, about an electrical storage apparatus, it is preferable that a said 2nd protection member is a dome shape which has the relief space of the pressure release valve deform | transformed in order to open | release the said pressure inside.
According to this, since the inner pressure of the case acts on the back surface of the valve body of the pressure release valve, when the pressure release valve is cleaved, the valve body of the pressure release valve turns up as a valve piece. At this time, since the valve piece enters the escape space, the turning-up of the valve piece is not hindered by the second protective member, and the pressure release valve can be quickly opened.

Moreover, about the electrical storage apparatus, the said pressure relief valve has a cleavage groove | channel on the outer surface.
According to this, foreign substances such as dust can be prevented from entering the cleavage groove by the first protective member, the cleavage groove can be quickly cleaved, and the pressure release valve can be cleaved quickly.

  The power storage device is a secondary battery.

  According to the present invention, while protecting the pressure relief valve, it is possible to efficiently release the pressure when the pressure is released, and to suppress scattering of foreign matters.

The perspective view which shows the external appearance of a secondary battery. The disassembled perspective view which shows a pressure release valve, a 1st protection member, and a 2nd protection member. The partial enlarged plan view which shows a pressure release valve, a 1st protection member, and a 2nd protection member. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3 showing the pressure release valve, the first protection member, and the second protection member. The partial expanded side sectional view which shows the pressure relief valve of the state which was cleaved. The partial perspective view which shows the pressure release valve of the state which was cleaved. 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, a secondary battery 10 as a power storage device has a case 11, and an electrode assembly 12 is accommodated in the case 11. The case 11 also contains an electrolyte solution together with the electrode assembly 12. The case 11 includes a bottomed cylindrical case main body 13 and a flat lid 14 that closes an opening for inserting the electrode assembly 12 into the case main body 13. Both the case main body 13 and the lid body 14 are made of metal (in this embodiment, aluminum). In addition, the secondary battery 10 of this embodiment is a rectangular battery whose appearance is a rectangular shape because the case body 13 has a bottomed rectangular tube shape and the lid body 14 has a rectangular flat plate shape. Moreover, the secondary battery 10 of this embodiment is a lithium ion battery.

  The electrode assembly 12 includes a positive electrode, a negative electrode, and a separator that insulates the positive electrode from the negative electrode. The positive electrode is configured by applying a positive electrode active material to both surfaces of a positive metal foil (aluminum foil). The negative electrode is configured by applying a negative electrode active material to both surfaces of a negative electrode metal foil (copper foil). The electrode assembly 12 has a stacked structure in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked and a separator is interposed between the electrodes. In addition, a positive electrode terminal 15 and a negative electrode terminal 16 are electrically connected to the electrode assembly 12. Each part of the positive electrode terminal 15 and the negative electrode terminal 16 is exposed to the outside of the case 11 from the lid body 14. Further, a ring-shaped insulating ring 17 a for insulating from the case 11 is attached to the positive terminal 15 and the negative terminal 16, respectively.

  The lid 14 of the case 11 is provided with a liquid injection hole 18 for injecting an electrolyte into the case 11 (case body 13). The liquid injection hole 18 is closed by a sealing member 19. Yes. The sealing member 19 is fixed to the outer surface 14 a of the lid body 14 and is exposed outside the case 11.

  As shown in FIG. 2, the case 11 includes a pressure release valve 20. The pressure release valve 20 is opened when the pressure in the case 11 reaches an open pressure that is a predetermined pressure so that the pressure in the case 11 does not increase excessively, and the inside and outside of the case 11 are communicated. In this embodiment, the pressure release valve 20 is located on the lid 14 of the case 11. The release pressure of the pressure release valve 20 is set to a pressure at which the case 11 itself and the joint between the case body 13 and the lid body 14 can be broken before cracks or breakage can occur.

  As shown in FIGS. 2, 3, and 4, the pressure release valve 20 has a thin plate-like valve body 21 that is thinner than the plate thickness of the lid body 14. The valve body 21 is located at the bottom of the concave portion 22 provided in the lid body 14 and is formed integrally with the lid body 14. The valve body 21 has a cross groove 23 on the outer surface 21a as a cleavage groove. The intersecting groove 23 has two straight grooves 24 and 25 extending linearly between the peripheral edges of the valve body 21. In this embodiment, the straight grooves 24 and 25 are V-shaped grooves. The intersecting groove 23 has an intersecting portion P at a position where the two straight grooves 24 and 25 intersect. In the intersection P, the pressure applied from the inside of the case 11 is likely to concentrate, and is assumed as a cleavage starting point which is a starting point when the valve body 21 starts to cleave.

  The secondary battery 10 has a first protective member 26 attached to the outer surface 14 a of the lid body 14. The first protective member 26 has a rectangular shape in plan view. Moreover, the 1st protection member 26 is the adhesive tape made from a resin film, and is a thin film form. When the valve body 21 of the pressure release valve 20 is cleaved and divided into a plurality of (for example, four) valve pieces S1 to S4, the first protection member 26 is broken so as to be broken by the valve pieces S1 to S4. The thickness of the protection member 26 is set. The first protection member 26 has a shape that covers the entire periphery of the valve body 21 including the entire outer surface 21 a of the valve body 21 in the pressure release valve 20. Accordingly, the entire outer surface 21 a of the valve body 21 of the pressure release valve 20 is covered from the outside of the case 11 by the first protection member 26.

  The adhesive surface of the first protective member 26 is affixed on the outer surface 14 a of the lid body 14 outside the peripheral edge of the pressure release valve 20. The first protective member 26 is not attached to the outer surface 21 a of the valve body 21, and the adhesive surface of the first protective member 26 is separated from the outer surface 21 a of the valve body 21.

  The secondary battery 10 includes a second protection member 27 that covers the pressure release valve 20 from the outer surface side via the first protection member 26. The second protective member 27 is a dome-shaped porous body, specifically a dome-shaped wire mesh. The second protective member 27 is formed by knitting the same aluminum wire as the case 11 through a square eye, and has a plurality of meshes 27a as holes. In the second protective member 27, the mesh indicating the number of meshes 27a per inch is preferably 100 mesh or more. This is for suppressing the scattering of the contents from the inside of the case 11 to the outside of the case 11 when the pressure release valve 20 is broken, and the second protective member 27 does not hinder the pressure release to the outside of the case 11. It is also to do so.

  The second protective member 27 has an annular opening edge 27b. The size of the circle formed by the opening edge 27 b of the second protection member 27 is larger than the outer shape of the valve body 21 in the pressure release valve 20. The opening edge 27 b of the second protection member 27 is joined to a position surrounding the valve body 21 of the pressure release valve 20 on the outer surface 14 a of the lid body 14. The opening edge 27b of the second protection member 27 penetrates the first protection member 26 and is joined to the outer surface 14a of the lid body 14 by welding.

  The second protective member 27 has a shape that swells in a dome shape from the outer surface 14 a of the lid body 14. The second protective member 27 has a substantially semispherical escape space 28 on the inner side. In the escape space 28, the valve pieces S1 to S4 turned up when the valve body 21 is cleaved enter. The site | part which opposes the periphery of the valve body 21 among the inner surfaces of the 2nd protection member 27 exists in a position higher than the position of the front-end | tip when each valve piece S1-S4 is turned up. For this reason, even if each valve piece S <b> 1 to S <b> 4 is turned up toward the second protection member 27, the tip of each valve piece S <b> 1 to S <b> 4 does not contact the inner surface of the second protection member 27.

Next, the operation of this embodiment will be described.
A plurality of secondary batteries 10 are integrated and used as a battery pack, and are used in a state where no duct for exhausting from the pressure release valve 20 is provided. Moreover, it cools with the air introduce | transduced toward the battery pack.

  During normal use of the secondary battery 10, relatively large foreign matters floating around the secondary battery 10 cannot pass through the mesh 27 a of the second protective member 27, and the second protective member 27 applies pressure from the relatively large foreign matters. The release valve 20 is protected. On the other hand, a relatively small foreign object such as dust may pass through the mesh 27a. However, the first protection member 26 protects the pressure release valve 20 from the relatively small foreign object.

  As shown in FIG. 5 and FIG. 6, if the pressure in the case 11 reaches the open pressure, the intersecting groove 23 is split starting from the intersecting portion P. When the intersecting groove 23 is cleaved, the valve body 21 is turned up outward while being divided into a plurality of (for example, four) valve pieces S1 to S4. The first protective member 26 is broken by the turned up valve pieces S1 to S4. Thereby, a large opening 29 is formed in the pressure release valve 20. The pressure in the case 11 is released to the outside of the case 11 through an opening 29 generated in the pressure release valve 20.

  At this time, the gas in the case 11 passes through the mesh 27 a of the second protective member 27 and is released to the outside of the case 11, and the pressure in the case 11 is released to the outside of the case 11. Even if the contents in the case 11 jump out of the opening 29, the contents are received by the second protection member 27, and the contents are prevented from scattering out of the second protection member 27.

According to the above embodiment, the following effects can be obtained.
(1) During normal use of the secondary battery 10, the first protective member 26 prevents relatively small foreign matter such as dust from adhering to the pressure release valve 20, and the valve body of the pressure release valve 20 by foreign matter. It is suppressed that 21 is damaged.

  (2) During normal use of the secondary battery 10, the second protective member 27 can protect the pressure release valve 20 from relatively large foreign matter. Further, when the internal pressure of the case 11 rises and the pressure release valve 20 is ruptured, even if the contents are ejected from the case 11, the contents can be prevented from being scattered by the second protective member 27. Moreover, even if the valve pieces S1 to S4 are separated from the lid body 14, the second protective member 27 can prevent the separated valve pieces from scattering.

  (3) The second protective member 27 has a plurality of meshes 27a. For this reason, while suppressing the scattering of the contents and the valve pieces, the second protective member 27 does not hinder the release of the pressure to the outside of the case 11 or the gas release, and the pressure can be released efficiently.

  (4) The second protective member 27 has a dome shape and has an escape space 28 inside. For this reason, when the pressure release valve 20 is cleaved, the second protective member 27 does not prevent the valve pieces S1 to S4 from turning up, and the pressure can be quickly released.

  (5) The pressure release valve 20 is a type that has a cross groove 23 in the valve body 21 and is torn from the cross groove 23. Even such a pressure release valve 20 is covered with the first protective member 26, so that foreign matter is prevented from entering the crossing groove 23, and the possibility that the crossing groove 23 will not be cleaved by the foreign matter is eliminated. it can.

  (6) The 1st protection member 26 is affixed on the position which surrounds the valve body 21, and is not affixed on the outer surface 21a of the valve body 21. FIG. For this reason, the first protection member 26 does not hinder the turning up of the valve pieces S1 to S4, and the pressure can be quickly released.

  (7) The second protection member 27 has a dome shape, and has a mesh 27 a on the entire second protection member 27. For this reason, when the pressure release valve 20 is cleaved, gas and pressure can be released from all directions of the second protective member 27.

Further, even when the second protective member 27 receives a pressure released to the outside of the case 11, the second protective member 27 is unlikely to become a resistance, and the second protective member 27 can be prevented from being detached from the lid body 14.
In addition, you may change the said embodiment as follows.

In embodiment, the pressure release valve 20 does not need to have the crossing groove 23 which is a cleavage groove in the valve body 21. FIG.
The cleavage groove may not be the intersecting groove 23, and may be a single straight line or a structure having a plurality of grooves that do not intersect each other.

The pressure release valve 20 may be configured such that a part of the valve body 21 is thin.
○ The mesh of the second protection member 27 may be changed as appropriate.
(Circle) the 2nd protection member 27 may be a magnitude | size which is a grade which the front-end | tip of valve piece S1-S4 contacts at the time of cleavage of the pressure relief valve 20. FIG.

(Circle) the 2nd protection member 27 may not be dome shape, and the shape of the 2nd protection member 27 may be changed suitably.
In the embodiment, the second protection member 27 is made of the same aluminum as the lid body 14, but the second protection member 27 may be made of a metal different from the lid body 14.

The second protective member 27 may have a flat plate shape as long as it has a mesh 27a.
(Circle) the 1st protection member 26 may not be a resin film, and if it can be fractured | ruptured by the valve pieces S1-S4 at the time of cleavage of the pressure release valve 20, you may change suitably metal foil, a nonwoven fabric, cloth, paper, etc.

The first protective member 26 may not be made of wire mesh, and may be formed by opening a plurality of holes in a dome-shaped component made of resin or metal.
The secondary battery 10 may be used as a single unit.

  The pressure release valve 20, the first protection member 26 and the second protection member 27 are provided on the lid body 14, but the pressure release valve 20, the first protection member 26 and the second protection member 27 are connected to the side wall or bottom of the case body 13. It may be provided on the wall.

The positive electrode and the negative electrode may have a structure in which an active material is present on one side of a metal foil.
The secondary battery 10 may be a lithium ion secondary battery or another secondary battery. In short, any ion may be used as long as ions move between the active material for the positive electrode and the active material for the negative electrode and charge is transferred. Further, a capacitor may be used as the power storage device.

The electrode assembly 12 is not limited to the laminated type, and may be a wound type in which a belt-like positive electrode and a belt-like negative electrode are wound and laminated in layers.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.

  (A) The first protective member is a power storage device that is broken by a pressure release valve that is released from pressure.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 11 ... Case, 21a ... Outer surface, 20 ... Pressure release valve, 23 ... Crossing groove as cleavage groove, 26 ... First protection member, 27 ... Second protection member, 28 ... Relief space.

Claims (4)

In a power storage device having a pressure release valve for releasing the pressure inside the case to the outside of the case,
A first protective member in the form of a thin film covering the entire outer surface of the pressure release valve;
And a porous second protective member that covers the pressure relief valve from an outer surface through the first protective member.   2. The power storage device according to claim 1, wherein the second protection member has a dome shape having a relief space for a pressure release valve deformed to release the pressure.   The power storage device according to claim 1, wherein the pressure release valve has a cleavage groove on an outer surface.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery.