JP5455768B2 - Power storage device - Google Patents

Description

  The present invention relates to an electricity storage device having an electrode laminate in which a positive electrode and a negative electrode are laminated via a separator, and the electrode laminate is hermetically sealed in a laminate film case together with an electrolytic solution.

  Energy storage systems such as load leveling devices such as photovoltaic power generation and wind power generation, instantaneous voltage drop countermeasure devices for electronic devices such as computers, and energy regeneration devices for electric vehicles and hybrid cars have a large energy capacity. There is a need for an electricity storage device that can be rapidly charged and discharged. Conventional lead-acid batteries and other secondary batteries are difficult to charge and discharge with a large current and have a short cycle life, so it is difficult to cope with the power storage system. Accordingly, in recent years, non-aqueous power storage devices have attracted attention as new power storage devices that can solve these problems.

  Currently, a lithium ion capacitor has been proposed as an electricity storage device capable of rapid charge / discharge and long life. This lithium ion capacitor includes an electrode laminate in which a positive electrode, a negative electrode, and a separator are laminated. Such an electrode laminate is accommodated in a laminate case made of, for example, a soft aluminum laminate foil, and the case is filled with an organic electrolyte containing lithium ions. In this lithium ion capacitor, when gas is generated in the laminate case during an abnormality such as overcharge, the internal pressure of the laminate case increases and the case expands. Conventionally, an internal pressure release mechanism for releasing the internal pressure in the laminate case is provided in order to prevent the laminate case from bursting in the event of an abnormality. As a specific example of the internal pressure release mechanism, for example, a part of the sealing portion of the laminate case is formed to be weaker than the fusion strength of other parts (specifically, the fusion width is narrowed or the fusion force is weakened). Safety mechanism (see, for example, Patent Document 1), a safety mechanism (for example, see Patent Document 2, etc.) in which a through-hole is provided in a part of the laminate case and a safety valve is attached to close the opening. Proposed.

JP 2007-53023 A JP 2007-157678 A

  However, in the safety mechanism of Patent Document 1, since the fusion strength of the sealing portion in the laminate case is partially weakened, there is a concern that moisture permeates from that portion. Also, the safety mechanism of Patent Document 2 has a configuration in which a through-hole is provided and closed with a safety valve, so that moisture permeates from that portion. When moisture enters the laminate case, lithium reacts to cause deterioration of the capacitor performance.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electricity storage device that can reliably release the internal pressure of the case when gas is generated while ensuring the reliability of the case. .

Means [1] to [ 3 ] for solving the above problems are listed below.

[1] An electricity storage device having an electrode laminate in which a positive electrode and a negative electrode formed in a sheet shape are laminated via a separator, and the electrode laminate is hermetically sealed in a case of a laminate film together with an electrolytic solution In the case, a fixed portion that is fixed in a state of sandwiching a portion on the outer peripheral side of the stacked body storage portion that stores the electrode stacked body in the case, and extended from the fixed portion and deformed at the time of gas generation An internal pressure release mechanism having a breaking portion that abuts the case and breaks the case, and the breaking portion is provided in a non-contact state with respect to the undeformed case before gas generation. An electricity storage device.

Therefore, according to the invention described in the means 1, it is not necessary to configure the internal pressure release mechanism by partially reducing the fusion strength or providing the opening at the sealing portion of the laminate case as in the prior art. That is, the internal pressure release mechanism can be provided without changing the case side. Therefore, the sealing part of the case can be fused with a uniform strength, and moisture can be reliably prevented from entering the case. Moreover, even if it is a thin case, it can fix by inserting | pinching the outer peripheral side part of a case with a fixing | fixed part, and the case swelled at the time of gas generation can be reliably broken at a fracture | rupture part. Thereby, the internal pressure of the case applied at the time of gas generation can be reliably released . In addition, the rupture portion is provided in a non-contact state with respect to the undeformed case before gas generation, and the rupture portion is not in contact with the case during normal use when no gas is generated. The case is not broken by vibration or the like, and the reliability of the case can be maintained.

  [2] In the means 1, the fixing portion is a U-shaped member that sandwiches an outer peripheral end portion of the case, and the fracture portion is opposed to the case at one end portion of the U-shaped member. A power storage device, wherein the power storage device is a cutting blade-like member.

  According to the invention described in the means 2, since the fixing portion is a U-shaped member, the outer peripheral end portion of the case can be securely sandwiched. Moreover, a fracture | rupture part can be arrange | positioned so that a case may be opposed by providing a fracture | rupture part in one edge part in a U-shaped fixing | fixed part. Furthermore, since the breaking portion is a cutting edge member, the case can be easily broken by coming into contact with the case deformed when gas is generated.

[ 3 ] Means 1 or 2 , wherein the internal pressure release mechanism is made of a member harder than the case.

According to the invention described in means 3 , since the internal pressure release mechanism is made of a member harder than the case, a sufficient force for breaking the case can be applied without following the deformation of the case.

As described above in detail, according to the inventions described in the means 1 to 3 , it is possible to provide an electricity storage device that can reliably release the internal pressure of the case when gas is generated while ensuring the reliability of the case.

The side view which shows the lithium ion capacitor of one embodiment. The top view which shows the lithium ion capacitor of one embodiment. Sectional drawing which shows the electrode laminated body of one Embodiment. The side view which shows an internal pressure release mechanism. Explanatory drawing for demonstrating the operation | movement at the time of gas release.

  Hereinafter, an embodiment in which the present invention is embodied in a lithium ion capacitor will be described in detail with reference to the drawings. FIG. 1 is a side view showing a lithium ion capacitor 10 according to the present embodiment, and FIG. 2 is a plan view of the lithium ion capacitor 10. FIG. 3 is a cross-sectional view showing the electrode laminate 11 constituting the lithium ion capacitor 10.

  As shown in FIGS. 1 to 3, the lithium ion capacitor 10 includes an electrode stack 11 having a structure in which positive electrodes 21 and negative electrodes 31 formed in a sheet shape are alternately stacked via separators 41. Yes. In the lithium ion capacitor 10, the electrode laminate 11 is hermetically sealed in the case 51 together with an electrolyte containing a lithium salt. In the lithium ion capacitor 10 of the present embodiment, the electrode laminate 11 has a thickness of about 6 mm and is configured as a thin electricity storage device.

  The separator 41 is made of a non-conductive porous body having durability against an electrolytic solution, an electrode active material, and the like and having continuous air holes. Usually, a nonwoven fabric or a porous body made of cellulose, such as glass fiber, polyethylene, polypropylene, or the like is used. The thickness of the separator 41 is preferably thin in order to reduce the internal resistance of the capacitor, but can be appropriately set in consideration of the amount of electrolyte retained, the flowability, the strength, and the like.

  The positive electrode 21 has a structure in which a positive electrode material 22 made of a carbon material is formed on a positive electrode current collector 23. As the carbon material forming the positive electrode material 22, activated carbon is used. This carbon material is kneaded and molded together with a conductive agent and a binder as necessary.

  The positive electrode current collector 23 is a member for collecting current while supporting the positive electrode material 22, and is formed using a conductive metal plate made of, for example, aluminum. The positive electrode current collector 23 is formed in a rectangular shape in plan view, and a tab 24 projects from one of the four sides. The tab 24 is connected to a positive electrode external terminal 25 made of aluminum (see FIGS. 1 and 2).

  The negative electrode 31 has a structure in which a negative electrode material 32 made of a material capable of occluding and releasing lithium ions is formed on a negative electrode current collector 33. Examples of the material for forming the negative electrode material 32 include carbon materials such as graphitic carbon, graphitizable carbon, and non-graphitizable carbon. Since these carbon materials have properties such as high reversibility, they are suitable as negative electrode materials. The carbon material for the negative electrode 32 is kneaded and molded with a conductive agent and a binder as necessary.

  The negative electrode current collector 33 is a member for collecting current while supporting the negative electrode material 32, and is formed using a conductive metal plate made of, for example, copper. The negative electrode current collector 33 is formed in a rectangular shape in plan view, and a tab 34 is drawn from one of the four sides. The tab 34 is connected to a negative electrode external terminal 35 made of copper (see FIGS. 1 and 2).

  As shown in FIGS. 1 and 2, the case 51 of the lithium ion capacitor 10 is a soft container processed into a rectangular bag shape using an aluminum laminate film obtained by laminating an aluminum foil on a resin film. The outer peripheral part 52 in the case 51 is sealed by heat sealing. Sealing by thermal fusion is performed in a state where the positive electrode external terminal 25 and the negative electrode external terminal 35 are sandwiched between the fusion portions. In the present embodiment, the sealing portion of the case 51 is formed so that the fusion width is equal and the fusion force is uniform.

  When the electrode stack 11 is housed in the case 51 in this way, the positive electrode external terminal 25 is drawn from one end portion (left end portion in FIG. 1) of the case 51 and the other end portion (FIG. 1). Then, the negative external terminal 35 is pulled out from the right end). Note that the case 51 may be formed using a metal laminate film material made of a metal foil other than the aluminum foil.

  As shown in FIGS. 1, 2, and 4, in the case 51 of the present embodiment, an internal pressure release mechanism 60 is provided at a position on the outer peripheral side of the stacked body storage portion 53 that stores the electrode stack 11. Yes. The internal pressure release mechanism 60 is fixed in a state where the outer peripheral end of the case 51 is sandwiched, and the case 51 extends from the fixed portion 61 and comes into contact with the case 51 deformed when gas is generated to break the case 51. It has the fracture | rupture part 62 to be made. The fixing portion 61 and the breaking portion 62 constituting the internal pressure releasing mechanism 60 are made of a metal member that is harder than the case 51. The fixing portion 61 is a member formed in a U-shape, and the breaking portion 62 is a cutting blade-like member provided so as to face the case 51 at one end portion 61 a of the U-shaped fixing portion 61. is there. In the internal pressure release mechanism 60, the end 61b of the fixing portion 61 opposite to the breaking portion 62 is fixed to the case 51 using an adhesive or the like, and the breaking portion 62 is attached to the undeformed case 51 before gas generation. It is provided in a non-contact state.

  Specifically, the fixing portion 61 is formed by pressing an elongated rod-shaped metal material made of brass or the like into a U shape. Further, the breaking portion 62 is formed integrally with the fixing portion 61 by performing cutting or polishing on the end portion 61 a of the fixing portion 61. The internal pressure release mechanism 60 may be configured by forming the fixing portion 61 and the breaking portion 62 separately and connecting the breaking portion 62 to one end 61 a of the fixing portion 61 by welding. In the present embodiment, the length of the fixing portion 61 is about 12 mm, and the interval between the one end portion 61a and the other end portion 61b in the fixing portion 61 is about 4 mm. The length and interval of the fixing portion 61 can be appropriately changed according to the size of the case 51. In addition, it is preferable that the space | interval (thickness of the internal pressure release mechanism 60) of each edge part 61a, 61b in the fixing | fixed part 61 is made narrower than the thickness of the laminated body accommodating part 53. FIG. In this case, when the plurality of lithium ion capacitors 10 are stacked and stored in the thickness direction, the internal pressure release mechanism 60 does not protrude from the stacked body storage portion 53, so that the same storage performance as in the conventional case can be ensured.

  In the lithium ion capacitor 10 configured as described above, when gas is generated in the case 51 due to an abnormality such as overcharging, the case 51 swells as shown in FIG. At this time, the case 51 is deformed in a direction in which the U-shaped fixing portion 61 of the internal pressure release mechanism 60 is pushed and widened, and a portion on the outer peripheral side of the case 51 is sandwiched between the internal pressure release mechanisms 60. And the fracture | rupture part 62 provided in the front-end | tip part of the fixing | fixed part 61 is pressed on the case 51 surface. Further, when the internal pressure of the case 51 rises, the case 51 is cracked along the cutting edge of the breaking portion 62, and the case 51 is broken. As a result, a hole is opened in the case 51 and the gas generated in the case 51 is released to the outside, so that the internal pressure of the case 51 is released.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) In the lithium ion capacitor 10 of the present embodiment, the internal pressure release mechanism 60 is provided at a position on the outer peripheral side of the case 51, and the internal pressure release mechanism 60 is in a state of sandwiching the outer peripheral end portion of the case 51. It has a fixing part 61 to be fixed and a breaking part 62 for breaking the case 51. When such an internal pressure release mechanism 60 is used, it is not necessary to partially weaken the fusion strength or provide an opening in the sealing portion of the case as in the prior art. That is, the internal pressure release mechanism 60 can be provided without changing the case 51 side. Accordingly, the sealed portion of the case 51 can be fused with a uniform strength, and moisture can be reliably prevented from entering the case 51 during normal use. Further, even the thin case 51 can be fixed by sandwiching the outer peripheral portion of the case 51 with the fixing portion 61, and the case 51 swelled when the gas is generated can be reliably broken at the breaking portion 62. it can. Thereby, since the internal pressure of the case 51 applied at the time of gas generation can be reliably released, the rupture of the case 51 can be prevented in advance.

  (2) In the internal pressure release mechanism 60 of the present embodiment, since the fixing portion 61 is a U-shaped member, the outer peripheral end portion of the case 51 can be securely sandwiched. Further, by providing the rupture portion 62 at one end of the U-shaped fixing portion 61, the rupture portion 62 can be arranged to face the case 51. Furthermore, since the fracture | rupture part 62 is a cutting blade-shaped member, it can contact | abut to the case 51 which deform | transformed at the time of gas generation, and can break the case 51 easily.

  (3) In the lithium ion capacitor 10 of the present embodiment, the fracture portion 62 of the internal pressure release mechanism 60 is not in contact with the case 51 during normal use where no gas is generated. For this reason, the case 51 is not accidentally broken by vibration or the like, and the reliability of the case 51 can be sufficiently maintained.

  (4) Since the internal pressure release mechanism 60 of the present embodiment is made of a metal member that is harder than the case 51, a sufficient force for breaking the case 51 can be applied without following the deformation of the case 51. it can.

  In addition, you may change embodiment of this invention as follows.

  -In above-mentioned embodiment, although the internal pressure release mechanism 60 was comprised by the metal member, you may comprise using a ceramic member etc. besides this. However, when the internal pressure release mechanism 60 is made of a metal member, the U-shaped fixing portion 61 and the cutting edge-shaped fracture portion 62 can be formed relatively easily, and the material cost can be reduced. This is preferable.

  -Although the internal pressure release mechanism 60 of the said embodiment was provided with the cutting edge-shaped fracture | rupture part 62, you may equip a sharply-pointed needle-like member as a fracture | rupture part besides this. Furthermore, the internal pressure release mechanism may be configured to provide a plurality of break portions 62 and to reliably break the case 51. Moreover, although the fixing | fixed part 61 was a U-shaped member, if it is the shape which pinches | interposes the outer peripheral edge part of case 51, it can change suitably. Furthermore, although the fixing portion 61 is fixed to the outer peripheral end portion of the case 51, the fixing portion 61 may be fixed in a state where the tab-shaped positive electrode external terminal 25 and the negative electrode external terminal 35 are sandwiched.

  In the lithium ion capacitor 10 of the above-described embodiment, the positive electrode external terminal 25 and the negative electrode external terminal 35 are drawn out in opposite directions, but the present invention is not limited to this, and the positive electrode external terminal 25 from the same direction. The negative electrode external terminal 35 may be pulled out.

  In the above embodiment, the present invention is embodied in the lithium ion capacitor 10, but the present invention can be embodied in other power storage devices as long as the power storage device includes a laminate film case. For example, the present invention may be embodied in an electric double layer capacitor or a lithium ion secondary battery.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiments described above are listed below.
(1) The electric storage device according to (1), wherein the fixing portion is fixed to a tab-like external terminal provided so as to protrude from the case.
(2) A positive electrode having a structure in which a positive electrode material made of a carbon material is applied to a sheet-like current collector, and a negative electrode having a structure in which a negative electrode material made of a material capable of occluding and releasing lithium is applied to the sheet-like current collector. A lithium ion capacitor that is hermetically sealed in a laminate film case together with an electrolyte solution containing a lithium salt. A fixed portion that is fixed in a state in which a portion on the outer peripheral side of the stacked body storing portion that stores the electrode stacked body is sandwiched, and a case that contacts the case that extends from the fixed portion and is deformed when gas is generated. A lithium ion capacitor comprising an internal pressure release mechanism having a breaking portion that breaks the battery.

DESCRIPTION OF SYMBOLS 10 ... Lithium ion capacitor 11 ... Electrode laminated body 21 ... Positive electrode 31 ... Negative electrode 41 ... Separator 51 ... Case 53 ... Laminate body accommodating part 60 ... Internal pressure release mechanism 61 ... Fixed part 61a ... One end part 62 ... Breaking part

Claims (3)

An electrical storage device having an electrode laminate in which a positive electrode and a negative electrode formed in a sheet shape are laminated via a separator, and the electrode laminate is hermetically sealed in a laminate film case together with an electrolyte solution. ,
In the case, a fixed portion that is fixed in a state of sandwiching a portion on the outer peripheral side of the stacked body storage portion that stores the electrode stacked body, and abuts on the case that extends from the fixed portion and is deformed when gas is generated. And an internal pressure release mechanism having a breaking portion for breaking the case ,
The electricity storage device , wherein the fracture portion is provided in a non-contact state with respect to the undeformed case before gas generation . The fixed portion is a U-shaped member that sandwiches the outer peripheral end portion of the case,
The power storage device according to claim 1, wherein the breaking portion is a cutting blade-like member provided to face the case at one end of the U-shaped member. The pressure release mechanism, the electric storage device according to claim 1 or 2, characterized in that it consists of rigid member than the case.

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