JP2011210390A - Battery and battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery and a battery module, which can cut off current without using the internal pressure of the battery or a fuse when heat is generated.SOLUTION: A secondary battery 1 includes a wound element 10, a case 40 housing the wound element 10, a negative terminal 51 disposed on the case 40, a lead 47 connecting the negative terminal 51 to the wound element 10, and a disconnection device 6 which breaks electrical connection between the negative terminal 51 and the lead 47. The negative terminal 51 has a hollow portion 55 housing the disconnection device 6. The lead 47 is disposed to traverse the hollow portion 55. The disconnection device 6 has: a cut member 61 which moves toward the lead 47 to cut it; and a press member 62 which is disposed to be opposite to the lead 47 with respect to the cut member 61 and when the internal temperature of the hollow portion 55 becomes equal to or higher than a given temperature, presses the cut member 61 toward the lead 47.

Description

  The present invention relates to a battery and a battery module having a function of interrupting current when heat is generated.

Rechargeable rechargeable batteries are used as power sources for various devices. In the automotive industry in particular, there is a rapid demand for hybrid cars and electric vehicles that are attracting attention from the viewpoint of environmental issues and energy conservation. Is growing.
The secondary battery may generate heat when an internal short circuit or overcharge (or overdischarge) occurs. For this reason, secondary batteries having a function of suppressing heat generation have been developed.

  For example, in Patent Document 1, a power storage element wound around a winding core is accommodated in a cylindrical outer can, an explosion-proof valve is installed at an opening of the outer can, and the explosion-proof valve and the power storage element are connected by a lead wire. An explosion-proof sealed battery is described in which when the explosion-proof valve is deformed due to an increase in internal pressure, the lead wire is peeled off from the explosion-proof valve by the stripper (or the lead wire is broken) to interrupt the current.

  Further, in Patent Document 2, a fuse is provided in the middle of a lead connecting an electrode plate and a terminal, and when an internal short circuit occurs, the rectangular lithium secondary battery that disconnects the electrode plate from which the internal short circuit has occurred by fusing the fuse is disconnected. A secondary battery is described.

  In Cited Document 3, an Sn alloy film is interposed between the lead extending from the negative electrode side of the laminated electrode group and the negative electrode terminal, and is generated between the lead and the negative electrode terminal when an excessive current flows. A prismatic non-aqueous electrolyte secondary battery is disclosed in which the Sn alloy film is melted by Joule heat generation to release the connection between the lead and the negative electrode terminal.

Japanese Patent No. 2701375 JP-A-8-50920 JP 2009-211136 A

  However, the technique described in Patent Document 1 is based on the assumption that a cylindrical case that easily resists internal pressure is used. For example, when the case has a square shape, the case itself is easily deformed by the internal pressure. Therefore, it was difficult to operate the explosion-proof valve under the set conditions. Further, in order to suppress the deformation of the case, if the thickness of the case is increased or a part that restricts the deformation is added, there is a problem that the battery is increased in size and weight.

  Furthermore, in the technique described in Patent Document 1, the explosion-proof valve is triggered by an increase in internal pressure due to a chemical reaction of the electrolytic solution. Therefore, when the composition of the electrolytic solution is set so that the performance of the battery is optimal, the current is reduced. It has been difficult to set the composition of the electrolyte so that the internal pressure at which the explosion-proof valve operates at the optimal timing (temperature) for shutting off. Therefore, the operation of the explosion-proof valve tended to be delayed. Further, when the case is broken from the outside and a foreign substance enters and an internal short circuit occurs, the internal pressure is released from the broken portion, so that the explosion-proof valve may not operate even if heat is generated.

  In addition, when a fuse is provided in the middle of the lead as in the techniques described in Patent Documents 2 and 3, the fuse becomes a resistor, which increases the internal resistance of the battery. Further, if the fuse is enlarged in order to reduce the internal resistance, the battery itself is also enlarged, and there is a possibility that the layout property is deteriorated. In addition, at the point of time when a large amount of current flows to blow the fuse, the short circuit and the temperature increase have progressed remarkably inside the battery, making it difficult to avoid heat generation at an early stage.

  The present invention has been made in view of these problems, and provides a battery and a battery module capable of interrupting current without using an internal pressure or a fuse of the battery when heat is generated. Is an issue.

  The present invention provides a power storage element, a case for housing the power storage element, a terminal provided in the case, a lead for connecting the terminal and the power storage element, and an electrical connection between the terminal and the lead. A connection release means for releasing the battery, wherein the terminal has a hollow portion that accommodates the connection release means, and the lead is disposed so as to cross the hollow portion, and the connection release means Cutting means for moving toward the lead to cut the lead, and the cutting means when the temperature in the hollow portion is arranged on the opposite side of the lead with respect to the cutting means and the temperature in the hollow portion is equal to or higher than a predetermined temperature. And pressing means for pressing toward the lead.

  According to such a configuration, the connection release means is accommodated in the hollow portion formed in the terminal, and the connection release means operates when the temperature in the hollow portion becomes equal to or higher than the predetermined temperature. The current can be cut off without depending on the increase in internal pressure. For this reason, for example, even when the case is deformed due to an increase in internal pressure, it is possible to prevent the heat generation by reliably operating the connection release means when the temperature of the battery exceeds a predetermined temperature. Moreover, since it is not necessary to provide a fuse in a lead | read | reed and a terminal, the increase in the internal resistance of a battery can be suppressed.

  The periphery of the portion of the lead where the cutting means abuts is supported by a support member having rigidity higher than that of the lead, and the support member has a hole through which the cutting means is inserted. Is preferred.

  According to such a configuration, since the lead is supported by the support member having higher rigidity than the lead, when the cutting member comes into contact with the lead, the lead is difficult to bend and force is easily applied to the lead. As a result, the lead can be easily cut by the cutting member. Further, since the support member has a hole that allows the cutting member to be inserted, the lead can be reliably cut.

Further, a portion of the hollow portion that accommodates the pressing unit is filled with a temperature increase inhibitor that suppresses a temperature increase of the power storage element, and the cutting unit is directed toward the lead in the terminal. It is preferable that a communication path that connects the space on the pressing means side and the space on the lead side with the cutting means interposed therebetween is provided.

According to such a configuration, when the connection releasing means is activated and the cutting means moves toward the lead, the space on the pressing means side and the space on the lead side sandwich the cutting means, Thus, the temperature rise inhibitor filled in the space on the pressing means side flows into the space on the lead side. The temperature rise inhibitor flowing into the lead side flows into the case, and heat generation inside the case is suppressed.

  The battery module according to the present invention is formed by connecting a plurality of the above-described batteries in parallel.

  When multiple batteries are connected in parallel, if one of the batteries has an internal short circuit and the potential of the battery drops, current flows from the other battery into the battery with the lowered potential. However, if the battery module is configured by connecting a plurality of batteries having the above-described connection release means in parallel, the lead of the battery having a lowered potential can be reliably cut, A battery with a lowered potential can be disconnected from the parallel circuit to suppress heat generation.

  ADVANTAGE OF THE INVENTION According to this invention, when heat_generation | fever arises, the battery and battery module which can interrupt | block an electric current, without using the internal pressure of a battery and a fuse can be provided.

(A) is a perspective view of the secondary battery which concerns on 1st Embodiment, (b) is a perspective view of a wound body. (A) is the side view (X1-X1 sectional view taken on the line of FIG. 1 (a)) of the secondary battery which concerns on 1st Embodiment, (b) is a ring sectional view (X2-X2 of FIG. 1 (a)). FIG. It is a figure which shows the manufacturing method of the secondary battery which concerns on 1st Embodiment in steps, (a) is a side view of the state which piles up a negative electrode sheet, a positive electrode sheet, and two separators, (b) is a perspective view. . It is sectional drawing which expands and shows a negative | minus terminal, (a) is II sectional view taken on the line shown in FIG. 1, (b) is II-II arrow sectional drawing of (a). It is IV-IV arrow sectional drawing of Fig.4 (a). It is a VV arrow sectional view of Drawing 4 (a). (A) is a perspective view of a support member, (b) is a bottom view of a support member. It is drawing for demonstrating operation | movement of a secondary battery, (a) is sectional drawing before lead cutting | disconnection, (b) is sectional drawing after lead cutting | disconnection. It is sectional drawing which expanded and showed the minus terminal of the secondary battery which concerns on 2nd Embodiment, (a) is sectional drawing before lead cutting | disconnection, (b) is sectional drawing after lead cutting | disconnection. It is sectional drawing which expanded and showed the negative | minus terminal of the secondary battery which concerns on 3rd Embodiment. It is a bottom view of the support member concerning a modification. It is the schematic of a battery module, (a) has shown the state before lead cutting | disconnection and (b) after lead cutting | disconnection, respectively.

  A first embodiment of the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description is omitted.

≪Configuration of secondary battery≫
As shown in FIG. 1, the secondary battery 1 according to the first embodiment is a lithium ion type secondary battery, and the outer shape thereof is rectangular, that is, a thin plate shape. Such secondary batteries 1 are arranged in parallel in the thickness direction (left-right direction), for example, and constitute a high-voltage battery of about 300 to 500 V, for example, such as an electric vehicle or a hybrid Used as a car storage battery.

  As shown in FIGS. 1 to 3, the secondary battery 1 is injected into the wound body 10, the insulating film 31 covering the wound body 10, the case 40 that houses the wound body 10, and the case 40. An electrolyte solution. In each figure, the electrolytic solution is omitted.

<Wound body>
The wound body 10 serving as a storage element includes a negative electrode sheet 11 (first electrode sheet), a positive electrode sheet 12 (second electrode sheet), and two separators 21 that electrically insulate the negative electrode sheet 11 and the positive electrode sheet 12 from each other. , 22. Specifically, as illustrated in FIGS. 3A and 3B, the wound body 10 is laminated in the order of a separator 21, a negative electrode sheet 11, a separator 22, and a positive electrode sheet 12, and the negative electrode sheet 11 and the positive electrode sheet 12. Is wound in such a way that the negative electrode sheet 11 is outside the positive electrode sheet 12, and then slightly crushed and deformed, and flattened in a cross-sectional sectional view. It is. The thickness of the wound body 10 in the left-right direction is, for example, about 19 mm.
In addition, the code | symbol 19 of FIG.3 (b) is a core material, and is extracted after preparation of the winding body 10. FIG.

Therefore, the wound body 10 has a separator 21, a negative electrode sheet 11, a separator 22, a positive electrode sheet 12, and a separator in the center in the axial direction (front-rear direction) and from the outside toward the center in the cross-section direction of the wound body 10. 21 and the negative electrode sheet 11,... Have a main body 13 (see FIG. 3A).
The wound body 10 has a negative electrode tab 14 (first current collecting tab) on the front side of the main body 13 in the axial direction, and a positive electrode tab 15 (second current collecting tab) on the rear side of the main body 13. Have.

<Wound body-negative electrode sheet>
The negative electrode sheet 11 includes a negative electrode current collector foil 11a having conductivity, and negative electrode active material layers 11b and 11b formed on both surfaces of the negative electrode current collector foil 11a, respectively (see FIG. 3A).
The negative electrode current collector foil 11a has a rectangular shape, and is made of, for example, a copper foil (for example, a thickness of 10 μm).

The negative electrode active material layer 11b is a layer mainly composed of a negative electrode active material for causing a battery reaction in the negative electrode, and a mixture of the negative electrode active material and a binder (adhesive) is applied to the negative electrode current collector foil 11a. It is formed by press working after coating. For example, the coating width is 120 mm, the thickness of the negative electrode sheet 11 after pressing is 100 μm, and the electrode density of the negative electrode sheet 11 is 1.5 g / cm ³ .

  The negative electrode sheet 11 has an uncoated portion 11c (uncoated portion) in which the negative electrode active material layer 11b is not formed on the front side (one side) and the negative electrode current collector foil 11a is exposed in a band shape. (For example, an uncoated width of 10 mm). And after winding, the above-mentioned negative electrode tab is made to adhere | attach the spiral-shaped uncoated part 11c extended ahead in an axial direction (front-back direction) by welding etc. in thickness direction (left-right direction). 14 is formed.

As the negative electrode active material, for example, a carbon material that occludes / releases lithium ions (LI ⁺ ) or an alloy that forms a metal compound with lithium (Li) can be used.
As the carbon material, for example, natural graphite, artificial graphite (for example, particle size 22 μm), activated carbon, carbon obtained by heat-treating a low-temperature carbon body (organic precursor) in an inert gas atmosphere, or the like can be used. Examples of low-temperature carbon bodies (organic precursors) include graphitizable carbon precursors such as pitch and mesophase pitch, and non-graphitizable carbon precursors such as phenol resin, xylene resin, PPS (PolyPhenylene Sulfide), and cellulose. Can be used.
For example, PVDF (PolyVinylidene DiFluoride) can be used as the binder.

<Wound body-positive electrode sheet>
The positive electrode sheet 12 includes a positive electrode current collector foil 12a having conductivity, and positive electrode active material layers 12b and 12b formed on both surfaces of the positive electrode current collector foil 12a, respectively (see FIG. 3A).
The positive electrode current collector foil 12a has a rectangular shape and is made of, for example, an aluminum foil (for example, a thickness of 12 μm).

The positive electrode active material layer 12b is a layer mainly composed of a positive electrode active material for causing a battery reaction in the positive electrode, and a mixture of the positive electrode active material, a conductive filler, and a binder (adhesive) is used as a positive electrode current collector foil. It is formed by applying to 12a and pressing. For example, the coating width is 120 mm, the thickness of the positive electrode sheet 12 after pressing is 100 μm, and the electrode density of the positive electrode sheet 12 is 3.85 g / cm ³ .

  The positive electrode sheet 12 has an uncoated portion 12c (uncoated portion) in which the positive electrode active material layer 12b is not formed on the rear side (one side) and the positive electrode current collector foil 12a is exposed in a band shape. (For example, uncoated width 10 mm). And after winding, the above-mentioned positive electrode tab is made to adhere | attach the spiral-shaped uncoated part 12c extended back in an axial direction (front-back direction) by welding etc. in a thickness direction (left-right direction). 15 is formed.

As the positive electrode active material, for example, powdery lithium oxide (LiNi _0.33 Mn _0.33 Co _0.33 O ₂ ) having an average particle diameter d50 = 12 μm can be used.
As the conductive filler, for example, acetylene black, ketjen black, or VGCF (Vapor Grown Carbon Fiber) can be used.
For example, PVDF (PolyVinylidene DiFluoride) can be used as the binder.

<Wound body-Separator>
The separators 21 and 22 are sheets (for example, having a thickness of 25 μm) for electrically insulating the negative electrode sheet 11 and the positive electrode sheet 12 and are porous so as to be impregnated with an electrolyte solution injected into the case 40. It is.
As such separators 21 and 22, for example, a nonwoven fabric composed of polyolefin-based (polyethylene, polypropylene, or the like) fibers can be used.

<Insulating film>
The insulating film 31 is a film for electrically insulating the wound body 10 and the case 40 and covers the outer surface of the wound body 10. Such an insulating film 31 is made of, for example, polyethylene or polypropylene.

<Electrolyte>
The electrolytic solution is a liquid for transporting ions (such as lithium ions) generated in the negative electrode sheet 11 and the positive electrode sheet 12 by a battery reaction, and is prepared by dissolving an electrolyte in a solvent.

Among the non-aqueous solvents, for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ -Butyrolactone (γ-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like can be used.
Such non-aqueous solvents may be used alone or in combination of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluoromethanesulfonic acid. Lithium salts such as lithium (LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₃ ) ₂ ] can be used.
The amount of electrolyte dissolved in the non-aqueous solvent is usually preferably about 0.2 mol / L to 2 mol / L.

Moreover, you may mix various ionic liquids, such as LiTFSI (lithium salt).
Furthermore, a gel electrolyte may be used as the electrolyte so that the electrolytic solution is held in a gel form. Examples of gel electrolytes that can be used include polyethylene oxide, polypropylene oxide, vinylidene fluoride, hexafluoropropylene derivatives and copolymers.

<Case>
The case 40 is a container that houses the wound body 10 covered with the insulating film 31, and includes a case main body 41 and a lid 42.

  The case body 41 is a box that opens upward and is thin in the left-right direction, and is made of aluminum alloy, SUS (stainless steel), resin, or the like. In particular, it is preferably made of an aluminum alloy and produced by impact molding or transfer press processing. Such a case body 41 is formed with, for example, a thickness of 0.8 mm, a thickness in the left-right direction of 40 mm, a height in the vertical direction of 120 mm, and a width in the front-rear direction of 160 mm.

  The lid 42 has a predetermined thickness (for example, 2 mm) and closes the opening of the case body 41. The lid 42 and the case body 41 are joined by, for example, laser welding.

  Further, a minus terminal 51 and a plus terminal 52 are attached to the lid 42. The minus terminal 51 and the plus terminal 52 are made of a metal such as copper, nickel, aluminum, SUS (stainless steel), or an alloy thereof.

  The negative terminal 51 is electrically connected to the negative electrode tab 14 of the wound body 10 via the lead 47. The lead 47 is formed of a copper alloy plate having a thickness of 0.3 mm, for example. The lead 47 and the negative electrode tab 14 or the negative terminal 51 are connected by, for example, ultrasonic welding.

  On the other hand, the plus terminal 52 is electrically connected to the positive electrode tab 15 of the wound body 10 via the lead 48. The lead 48 is made of, for example, an aluminum alloy plate having a thickness of 0.5 mm. The lead 48 and the positive electrode tab 15 or the plus terminal 52 are connected by, for example, ultrasonic welding.

  The lead 47 and the lead 48 are plate-shaped pieces that are substantially L-shaped and have electrical conductivity in a cross-sectional sectional view.

  Further, an injection hole 45 for injecting an electrolytic solution is formed at an appropriate position of the lid 42. The injection hole 45 is provided with a plug (not shown) in a detachable manner. In addition, the injection hole 45 is provided with an explosion-proof valve (not shown) for releasing the pressure when the electrolyte inside the case 40 expands due to heat generation. As the explosion-proof valve, a known safety valve that opens when the inside of the case 40 reaches a predetermined pressure or more can be used.

  Next, the structures of the minus terminal 51, the connection release device 6, and the support member 7 will be described with reference to FIGS.

<Terminal>
The minus terminal 51 of the first embodiment has a function of accommodating a connection release device 6 described later. The negative terminal 51 mainly includes a base 53 fixed to the lid 42, a protrusion 54 protruding from the upper surface of the base 53, and a hollow portion 55 formed inside the base 53 and the protrusion 54. .

  The base 53 is a flat member formed in a rectangular shape in plan view. On the side surface of the base 53, a concave groove 53 a that fits the lid 42 is formed over the entire circumference. Further, a locking piece 53b for locking a support member 7 to be described later is formed on the lower end edge of the side surface in the front-rear direction of the base portion 53 (see FIG. 4B). The upper surface of the locking piece 53b is inclined so as to become higher as the distance from the base 53 increases.

  A hollow portion 55 is opened on the bottom surface 53 c of the base portion 53. The lead 47 is installed so as to cross the opening 55a in the left-right direction. Thus, the lead 47 faces (opens) the opening 55a of the hollow portion 55. The width of the lead 47 is smaller than the diameter of the hollow portion 55.

  As shown in FIG. 4A, among the leads 47 arranged along the bottom surface 53c of the base portion 53, there is a case where the tip portion 47a (hereinafter referred to as “tip portion 47a”) sandwiching the opening 55a. ) Is fixed to the bottom surface 53c of the base 53 by ultrasonic welding. In addition, an insulating film 49 is attached to a portion 47b (hereinafter sometimes referred to as a “base end portion 47b”) on the wound body 10 side of the lead 47 with the opening 55a interposed therebetween. It is insulated from the bottom surface 53 c of 53.

  The protruding portion 54 is a portion to which a wiring or the like extending from an external device is connected, and is formed in a cylindrical shape. For example, a screw groove (not shown) is formed on the outer peripheral surface of the protruding portion 54.

  The hollow portion 55 is a portion that accommodates a connection release device 6 to be described later, and is formed in a circular shape in a sectional view. The hollow portion 55 accommodates a cutting member 61 and a pressing member 62 constituting the connection release device 6. The hollow portion 55 is closed at the upper end portion, and the lower end portion opens to the bottom surface 53 c of the base portion 53.

  A communication passage 55b is recessed along the vertical direction in the lower part (closer to the opening part 55a) of the inner peripheral surface of the hollow part 55. The communication path 55b is a path that connects the space on the pressing member 62 side and the space on the lead 47 side when the cutting member 61 moves downward. In the first embodiment, four communication paths 55b are formed at equal intervals in the circumferential direction over a height range corresponding to the base 53 (see FIG. 5).

<Connection release device 6>
The connection release device (connection release means) 6 is a device for releasing the electrical connection between the minus terminal 51 and the lead 47, and includes a cutting member (cutting means) 61 for cutting the lead 47, and the cutting member 61 as the lead 47. And a pressing member (pressing means) 62 that presses toward it.

The cutting member 61 has a piston portion 63 that is in sliding contact with the inner peripheral surface of the hollow portion 55, and a cutting portion 64 that comes into contact with and cuts the lead 47.
The piston part 63 is a disk-shaped member formed substantially the same diameter as the inner diameter of the hollow part 55, and partitions the hollow part 55. An annular groove 63a is recessed in the outer peripheral surface of the piston portion 63, and a stopper 63b is installed in the annular groove 63a (see FIG. 6). The stopper 63b is a member having a C shape in plan view, and is made of a shape memory alloy. The stopper 63b strongly contacts the inner peripheral surface of the hollow portion 55 at a normal temperature (less than a predetermined temperature) and restricts the movement of the piston portion 63. When the temperature exceeds the predetermined temperature, the stopper 63b is contracted in diameter. Is allowed to move. The height dimension of the piston part 63 is smaller than the length dimension of the communication path 55b.
As shown in FIG. 4A, the cutting portion 64 has a triangular shape in a cross-sectional view and has a sharp tip. The base end portion (upper end portion) of the cutting portion 64 is fixed to the bottom surface of the piston portion 63.

  The pressing member 62 expands when the temperature inside the hollow portion 55 (more specifically, the portion of the hollow portion 55 above the cutting member 61) is equal to or higher than a predetermined temperature. It has a function of pressing and moving to the lead 47 side. The pressing member 62 of the first embodiment is made of a solid, liquid, gas, or the like that starts a reaction at a predetermined temperature and causes volume expansion due to gas generation or gas expansion. The temperature at which the pressing member 62 starts to expand is appropriately set within a range of 100 ° C. to 200 ° C., for example. Moreover, as a raw material of the press member 62, organic foaming agents, such as carbonates, such as sodium hydrogencarbonate, and azodicarbonamide, can be used, for example.

  The pressing member 62 is designed to start volume expansion at a temperature lower than the temperature at which the internal pressure of the case 40 reaches the internal pressure at which the explosion-proof valve installed in the injection hole 45 (see FIG. 1) operates. Yes. Thereby, an electric current can be interrupted earlier than the internal pressure of the case 40 is released.

Further, the pressing member 62 is configured to generate an inert gas such as argon, nitrogen, carbon dioxide, etc. as a temperature increase inhibitor for suppressing a temperature increase inside the case 40. That is, the pressing member 62 of the first embodiment also serves as a temperature rise inhibitor.
The substance that generates the temperature rise inhibitor may be configured separately from the pressing member 62 and installed in the hollow portion 55 together with the pressing member 62.

<Supporting member>
As shown in FIGS. 4 and 7, the support member 7 is a member that supports the lead 47 so that the lead 47 can be easily cut by the cutting member 61. The support member 7 is made of an insulating material such as synthetic resin. The support member 7 includes a flat plate-like support portion 71, locking portions 72 and 72 erected on both edges in the front-rear direction of the support portion 71, a hole portion 73 formed in the approximate center of the support portion 71, It has.

  The support portion 71 is formed in a rectangular shape in plan view, and is disposed to face the bottom surface 53 c of the base portion 53 of the minus terminal 51. A lead 47 is sandwiched between the support portion 71 and the bottom surface 53 c of the base portion 53. The support portion 71 is formed to have higher rigidity than the lead 47 by, for example, making the thickness dimension larger than that of the lead 47 or forming the support portion 71 with a material harder than the lead 47.

  The locking portion 72 is a portion that locks on a locking piece 53 b provided on the base 53 of the negative terminal 51. The locking portion 72 includes a wall portion 72a that rises from both front and rear edges of the support portion 71, and an extending portion 72b that extends inward from the tip of the wall portion 72a. The lower surface of the extension part 72b is inclined so as to become lower as the distance from the wall part 72a increases. As a result, the lower surface of the locking portion 72 is hooked on the upper surface of the locking piece 53 b inclined in the opposite direction, so that the support member 7 is difficult to come off from the base portion 53 of the negative terminal 51.

  The hole portion 73 is a through hole for allowing the cutting portion 64 of the cutting member 61 that has cut the lead 47 to be inserted. The hole 73 is formed at a position corresponding to the cutting part 64. The length of the hole 73 is formed to be larger than the diameter of the hollow portion 55.

  The support member 7 ultrasonically welds the tip 47a of the lead 47 to the bottom surface 53c of the negative terminal 51 and attaches the insulating film 49 to the base end 47b of the lead 47, and then from below the lead 47. It is attached to the locking piece 53b of the minus terminal 51.

<Operation of secondary battery>
Next, the operation of the secondary battery 1 according to the first embodiment will be described with reference to FIG.

In a normal energized state, as shown in FIG. 8A, the cutting member 61 of the connection release device 6 has a stopper 63 b installed in the annular groove 63 a of the piston portion 63 that strongly hits the inner peripheral surface of the hollow portion 55. By being in contact therewith, the hollow portion 55 is fixed at a position spaced upward from the opening 55a. Further, the pressing member 62 of the connection release device 6 is enclosed in a space above the cutting member 61 (more specifically, a space opposite to the lead 47 with respect to the cutting member 61).
The lead 47 is disposed so as to cross the opening 55 a of the hollow portion 55, and is supported by the support member 7 from below.
The leading end 47 a of the lead 47 is connected to the bottom surface 53 c of the minus terminal 51 so that the wound body 10 can be charged and discharged.

  When the secondary battery 1 is overcharged or an internal short circuit occurs and the inside of the case 40 generates heat, the heat generation causes the minus terminal 51 to be heated, and consequently the inside of the hollow portion 55 of the minus terminal 51 also. It will be heated. And when the temperature of the hollow part 55 reaches predetermined temperature, reaction of the press member 62 will start and gas will be generated. Moreover, the diameter of the stopper 63b formed of the shape memory alloy is reduced, and the cutting member 61 can be slid.

  Then, as shown in FIG. 8B, the cutting member 61 is pressed by the gas and moves toward the lead 47, and the leading end portion of the cutting portion 64 formed sharply cuts the lead 47. Since the base end portion 47 b of the lead 47 is insulated from the minus terminal 51 by the insulating film 49, the lead 47 is cut at a portion facing the hollow portion 55, whereby the wound body 10 and the minus terminal 51 are separated. The electrical connection is released. Thereby, inflow of the electric current to the secondary battery 1 stops, and heat_generation | fever stops.

  Further, when the cutting member 61 moves downward from the upper end portion of the communication path 55b, the upper space and the lower space of the cutting member 61 communicate with each other via the communication path 55b. As a result, a temperature rise inhibitor such as an inert gas contained in the gas generated from the pressing member 62 flows into the case 40 through the communication passage 55b. As a result, the temperature rise of the wound body 10 and the electrolytic solution is prevented.

<Effects of secondary battery>
The secondary battery 1 according to the first embodiment is configured as described above, and thereby has the following effects.
That is, in the secondary battery 1 according to the first embodiment, the connection release device 6 is installed in the hollow portion 55 formed in the negative terminal 51, and the temperature in the hollow portion 55 is a predetermined temperature. Since the cutting member 61 moves and cuts the lead 47 when the above is reached, the connection between the negative terminal 51 and the lead 47 is released without depending on the pressure inside the case 40. be able to. Therefore, even when the case 40 has a square shape, there is no need for reinforcement, and the case can be reduced in size and weight.

  Further, since the hollow portion 55 is formed inside the minus terminal 51, it is difficult for deformation and the like to occur, so there is little variation in pressure, and the cutting member 61 can be moved reliably. Moreover, since the minus terminal 51 has a hollow structure, the minus terminal 51 can be reduced in weight. Further, since the connection release device 6 is installed inside the minus terminal 51, the installation space for the wound body 10 of the case 40 is not sacrificed.

  Further, since the composition of the pressing member 62 (that is, the reaction start temperature of the pressing member 62) can be designed regardless of the composition of the electrolytic solution, the connection release device is optimized while optimizing the charge / discharge performance of the secondary battery 1. It becomes easy to optimize the operating conditions of 6. Thereby, it is possible to prevent the operation of the connection release device 6 from being delayed.

  Further, even when the case 40 is broken from the outside and a foreign substance enters and an internal short circuit occurs, the pressing member 62 generates gas and the cutting member 61 when the temperature inside the case 40 exceeds a predetermined temperature. Is pressed and the lead 47 is cut, so that heat generation can be stopped even if the internal pressure of the case 40 does not increase. Further, since it is not necessary to provide a fuse or the like on the lead 47, the internal resistance of the secondary battery 1 does not increase.

  In addition, the secondary battery 1 according to the first embodiment includes the support member 7 having higher rigidity than the lead 47, and the support member 7 has a hole 73 through which the cutting member 61 passes. The deformation of the lead 47 can be suppressed, and the lead 47 can be reliably cut by the cutting member 61.

Next, a secondary battery 1A according to the second embodiment will be described with reference to FIG.
In the following description, differences from the first embodiment will be mainly described, and the same components as those described in the first embodiment will be denoted by the same reference numerals, and redundant description will be omitted. The secondary battery 1A according to the second embodiment is mainly different from the secondary battery 1 according to the first embodiment in that the pressing member 65 is made of a shape memory alloy.

  As shown to Fig.9 (a), the press member 65 of 2nd Embodiment is comprised by the metal member made from a shape memory alloy formed in the shape like a helical spring. The lower end side of the pressing member 65 is fixed to the cutting member 61, and the upper end side of the pressing member 65 is fixed to the bottom plate portion 66. The pressing member 65 has a shape (see FIG. 9A) in which a helical spring is compressed at a normal temperature (for example, less than 65 ° C.), and becomes a predetermined temperature or higher (for example, 85 ° C. or higher). Sometimes, it is deformed into a shape (see FIG. 9B) in which the helical spring is extended.

  A step 55c is formed around the opening 55a on the lower end side of the hollow portion 55 of the second embodiment. The step portion 55c has a function as a stopper for restricting the movement (protrusion) of the cutting member 61. Further, an opening 55d is formed on the upper end side of the hollow portion 55. After the connection release device 6 is installed in the hollow portion 55 from the opening 55d, the bottom plate portion 66 is welded to the opening 55d all around. It is blocked by that.

  In the secondary battery 1A, when the temperature inside the hollow portion 55 becomes equal to or higher than a predetermined temperature, as shown in FIG. 9B, the pressing member 65 expands, and the cutting member pressed by the pressing member 65 61 moves toward the lead 47. Thereby, the cutting part 64 of the cutting member 61 contacts the lead 47, and the lead 47 is cut. As a result, the wound body 10 and the negative terminal 51 are electrically disconnected, charging (or discharging) of the secondary battery 1 is stopped, and heat generation is stopped.

  According to the secondary battery 1A as described above, the operational effect is substantially the same as that of the secondary battery 1 according to the first embodiment, and the pressing member 65 is made of a shape memory alloy. The design of the operating temperature is simple and reliable as compared with the first embodiment.

Next, a secondary battery 1B according to the third embodiment will be described with reference to FIG.
In the following description, differences from the first embodiment will be mainly described, and the same components as those described in the first embodiment will be denoted by the same reference numerals, and redundant description will be omitted. In the secondary battery 1B according to the third embodiment, the base 57 of the negative terminal 51 is enlarged, and the hollow portion 55 is formed at a position shifted from the protruding portion 54 of the base 57. Mainly different from the one embodiment.

As shown in FIG. 10, the base portion 57 of the negative terminal 51 protrudes on one side with respect to the protruding portion 54. And the hollow part 55 which accommodates the connection cancellation | release apparatus 6 is formed in this protruding part 57a among the base parts 57. As shown in FIG.
Further, the support member 7 is also formed in a large size in accordance with the size of the base portion 57, and a hole portion 73 is formed at a position corresponding to the hollow portion 55.

According to such a configuration, the following operational effects can be obtained in addition to the operational effects of the secondary battery 1 according to the first embodiment.
That is, according to the secondary battery 1 </ b> B according to the third embodiment, the hollow portion 55 that houses the connection release device 6 is provided at a position different from the protruding portion 54 to which an external connection member (not shown) such as a bus bar is attached. Therefore, when the external connection member is attached to the projecting portion 54 with a screw or the like, the rigidity of the projecting portion 54 can be ensured and no axial force is applied to the hollow portion 55. Airtightness can be ensured. Moreover, the freedom degree of the dimension of the connection release apparatus 6 improves.

  In addition, in 3rd Embodiment, although it demonstrated using the press member 62 of the type which generate | occur | produces gas and presses the cutting member 61, it replaces with this and cut | disconnects using the shape memory alloy demonstrated in 2nd Embodiment. A pressing member 65 of a type that presses the member 61 may be used.

Next, a modified example of the support member 7 will be described in detail with reference to FIG.
In the following description, differences from the first embodiment will be mainly described, and the same components as those described in the first embodiment will be denoted by the same reference numerals, and redundant description will be omitted. The support member 7A according to the modified example is different from the first embodiment described above in that an insulating portion 75 and a notch portion 76 are provided.

As shown in FIG. 11, the insulating portion 75 is a thin plate (film-like) portion extending from the locking portion 72 of the support member 7 </ b> A, and serves as an alternative to the above-described insulating film 49. The insulating portion 75 is disposed on the base end portion 47 b of the lead 47 by bending the connecting portion 75 a with the locking portion 72 inward (upward).
The notch 76 is formed at a position corresponding to a portion where the lead 47 is ultrasonically welded to the minus terminal 51. The leading end 47 a of the lead 47 is exposed at the notch 76.

According to the support member 7A according to such a modification, the lead 47 can be attached to the minus terminal 51 after the lead 47 is attached to the support member 7A.
Specifically, first, the lead 47 is attached to the support member 7 </ b> A, and the insulating portion 75 is bent and disposed on the base end portion 47 b of the lead 47. Next, the locking portion 72 of the support member 7 </ b> A to which the lead 47 is attached is locked to the locking piece 53 b of the minus terminal 51. Thereby, the insulating part 75 is arrange | positioned between the base end part 47b of the lead | read | reed 47, and the bottom face 53c of the negative | minus terminal 51, and both are insulated. And the front-end | tip part 47a of the lead 47 exposed from the notch 76 is welded to the bottom face 53c of the minus terminal 51 using an ultrasonic welding machine (not shown). If it does in this way, the freedom degree of the assembly order of the secondary battery 1 can be ensured, and productivity will improve.

  Next, with reference to FIG. 12, a battery module 100 formed by connecting a plurality of secondary batteries 1 according to the first embodiment in parallel will be described. In the following description, the same components as those described in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 12A, the battery module 100 is obtained by connecting three secondary batteries 1 (hereinafter referred to as “secondary batteries 1L, 1M, 1R” in parallel from the left side of FIG. 12) in parallel. is there. The negative side of the battery module 100 is connected to an external load M (for example, an assist motor of a hybrid vehicle) via the wiring 8. Further, the positive side of the battery module 100 is connected to the external load M via the wiring 9.

  Here, when a metal piece K such as a nail is pierced into the central secondary battery 1M due to some impact, an internal short circuit occurs, and the potential of the secondary battery 1M decreases. Then, the current I flows from the other secondary batteries 1L, 1R having a high potential into the secondary battery 1M having a low potential, the vicinity of the minus terminal 51 generates heat, and the temperature of the minus terminal 51 rises.

  At this time, since the connection release device 6 is installed in the negative terminal 51, when the temperature of the negative terminal 51 becomes equal to or higher than a predetermined temperature, the connection release device 6 is activated and leads 47 of the secondary battery 1M. (See FIG. 4) is cut. Thereby, as shown with a broken line in FIG.12 (b), the secondary battery 1M is cut off from a parallel circuit, the inflow of the electric current I stops, and a temperature rise stops.

  Thus, if the battery module 100 is configured by connecting a plurality of the secondary batteries 1 (1L, 1M, 1R) according to the first embodiment in parallel, the lead 47 of the secondary battery 1M with a lowered potential (FIG. 8). (See (b)) can be reliably disconnected, and the secondary battery 1M having a lowered potential can be disconnected from the parallel circuit to suppress heat generation.

  As mentioned above, although embodiment of this invention was described in detail with reference to drawings, this invention is not limited to this, In the range which does not deviate from the main point of invention, it can change suitably.

  For example, in the first embodiment, the case 40 has a square shape, but the present invention is not limited to this, and the shape of the case 40 can be freely set.

  In the first embodiment, the hollow portion 55 is provided in the minus terminal 51. However, by forming the hollow portion 55 in the plus terminal 52 and installing the connection release device 6, and cutting the plus-side lead 48, You may comprise so that an electric current may be interrupted | blocked.

  In the description of the battery module 100, a plurality of the secondary batteries 1 according to the first embodiment are connected in parallel, but the secondary battery 1A according to the second embodiment and the secondary battery according to the third embodiment. 1B may be used.

1 Secondary battery (battery)
10 Winding body (electric storage element)
40 Case 47 Lead 49 Insulating film 51 Negative terminal 55 Hollow portion 55b Communication path 6 Connection release device (connection release means)
61 Cutting member (cutting means)
62 Pressing member (pressing means)
7 Supporting member 73 Hole

Claims (4)

An electrical storage element, a case that houses the electrical storage element, a terminal provided in the case, a lead that connects the terminal and the electrical storage element, and a connection release that releases an electrical connection between the terminal and the lead A battery comprising means,
The terminal has a hollow portion for accommodating the connection release means,
The lead is installed so as to cross the hollow portion,
The connection release means moves toward the lead and cuts the lead, and is disposed on the opposite side of the lead with respect to the cutting means, and the temperature in the hollow portion is equal to or higher than a predetermined temperature. And a pressing means for pressing the cutting means toward the lead. The periphery of the portion of the lead where the cutting means abuts is supported by a support member having higher rigidity than the lead,
The battery according to claim 1, wherein the support member has a hole through which the cutting means is inserted. A portion of the hollow portion that accommodates the pressing means is filled with a temperature increase inhibitor that suppresses a temperature increase of the power storage element,
The terminal is provided with a communication path that communicates the space on the pressing means side and the space on the lead side with the cutting means sandwiched when the cutting means moves toward the lead. The battery according to claim 1, wherein the battery is a battery.   A battery module formed by connecting a plurality of the batteries according to any one of claims 1 to 3 in parallel.

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