JP2011181409A - Battery and battery module - Google Patents

Abstract

To provide a battery capable of preventing the deterioration and failure of the battery by reliably limiting or cutting off the current.
A positive electrode terminal includes a cylindrical portion 511 having one end closed and a flange portion 512. The outer member 51 is disposed and fixed inside the case 30; A base portion 521 that is connected to the cylindrical portion 511 and a protrusion portion 522 that is slidably fitted into the tubular portion 511, and the base portion 521 is in contact with the flange portion 512 and is electrically connected to the outer member 51. A member 52, a locking claw 53 that maintains an electrical connection state between the inner member 52 and the outer member 51 in a normal state, and a thermal expansion material 59 that generates a driving force for sliding the inner member 52 by heat. When the battery 1 generates heat, due to the expansion force of the thermal expansion material 59, the connection by the locking claw 53 is released, and the inner member 52 slides in a direction in which the base portion 521 is separated from the flange portion 512. Electricity between the inner member 52 and the outer member 51 A battery 1 connection is limited or blocked.
[Selection] Figure 5

Description

  The present invention relates to a battery and a battery module. More specifically, the present invention relates to a battery and a battery module provided with a current interruption mechanism that prevents deterioration and failure of the battery.

  Conventionally, large-sized lithium ion secondary batteries have been used as power sources for electric vehicles and hybrid vehicles. This lithium ion secondary battery is an assembled battery formed by connecting a plurality of single cells (hereinafter referred to as cells), and outputs a voltage necessary as a power source.

  By the way, in the case where a plurality of cells are connected in parallel in order to connect the lithium ion secondary batteries in parallel and reduce the current load of each cell, if one of the plurality of cells is short-circuited, the short-circuited cell In addition to the heat generated by the internal energy, heat is generated by the current flowing from other parallel cells.

Various proposals have been made to prevent the above heat generation.
For example, an explosion-proof sealed battery has been proposed in which a lead-blocking stripper is attached to an explosion-proof valve that deforms in the internal pressure direction as the internal pressure increases (see Patent Document 1). In this explosion-proof sealed battery, when a predetermined internal pressure is reached, the current is interrupted by peeling the lead plate from the explosion-proof valve or by breaking the lead plate.

  Further, there has been proposed a rectangular lithium ion battery in which a fuse is disposed on a lead plate that electrically connects at least one current collecting ear portion of a negative electrode plate and a positive electrode plate and a battery terminal (Patent Document 2). reference). In this rectangular lithium ion battery, when an internal short circuit occurs, the fuse is melted and the electrode in which the internal short circuit occurs is disconnected from the battery.

  Further, a non-aqueous electrolyte secondary battery in which a negative electrode lead and a negative electrode terminal are electrically connected via an Sn alloy film that is melted by Joule heat generated between the negative electrode lead and the negative electrode terminal has been proposed (patent). Reference 3). In this nonaqueous electrolyte secondary battery, when an excessive current flows, the Sn alloy film is melted by Joule heat generated between the negative electrode lead and the negative electrode terminal, and the negative electrode lead and the negative electrode terminal are electrically cut off. .

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

  However, in the battery of Patent Document 1, a cylindrical cell is used as a condition for cutting off the lead because the pressure inside the cell is used. For this reason, in the case of a square cell that is easily deformed, in particular, a square cell using an aluminum case, there are individual differences in conditions for blocking the leads. In order to prevent the deformation of the case, it is necessary to increase the thickness of the case or to separately provide restraint parts. In this case, the weight of the battery increases.

  Moreover, in the battery of patent document 1, since it is a mechanism in which a valve operates due to an increase in internal pressure due to boiling of the electrolytic solution inside the cell, the electrolytic solution composition is determined according to the battery performance. For this reason, it is not possible to set an electrolyte composition with a lower boiling point that is optimal for current interruption, delaying current interruption, and adding an additive to the electrolyte causes problems such as an increase in battery resistance. there were.

  Moreover, in the battery of Patent Document 1, for example, when a nail or the like is stuck outside the cell and an internal short circuit occurs, the internal pressure is released, so that the valve cannot be operated. As a result, current may flow from other parallel cells to generate heat.

  On the other hand, when a fuse is interposed between the lead and the current collector as in the batteries of Patent Documents 2 and 3, there is a problem that the internal resistance of the battery increases because the fuse becomes a resistor. It was. In addition, when the battery is increased in size, the fuse itself is also increased in size, which is not suitable for in-vehicle use. Furthermore, since the current is cut off when a large current flows, it is after a short circuit or heat generation has already occurred inside the battery, and deterioration or failure of the battery cannot be avoided.

  The present invention has been made in view of the above, and the object thereof is to reliably limit or cut off the current to prevent deterioration or failure of the battery without relying on the internal pressure of the cell or the current cut-off mechanism using the fuse. The object is to provide a battery and a battery module.

In order to achieve the above object, in the first invention, a power storage element (for example, a power storage described later) including a positive electrode (for example, a positive current collector tab 15 described later) and a negative electrode (for example, a negative current collector tab 17 described later). Element 10), a positive terminal (for example, positive terminals 50, 60, 70, and 80 described later) electrically connected to the positive electrode, and a negative terminal (for example, a negative electrode described later) electrically connected to the negative electrode. A battery (for example, lithium ion secondary batteries 1, 2, 3, and 4 to be described later) provided with a terminal (100) and a case (for example, case 30 to be described later) that accommodates and holds the power storage element is provided.
In the battery according to the first aspect of the present invention, at least one of the positive electrode terminal and the negative electrode terminal has a cylindrical portion whose one end is closed and the other end opened (for example, a cylindrical portion 511 described later). A flange portion extending radially outward from the opening end (for example, a flange portion 512 described later), and the closed end side is disposed outside the case and the opening end side is disposed inside the case. An outer member (for example, an outer member 51 described later) fixed to the case, a base portion (for example, a base portion 521 described later) electrically connected to the one electrode, and the tube protruding from the base portion Projections (for example, projections 522 and 622 described later) that are slidably inserted into the shape portion, and are electrically connected to the outer member by contacting the base portion with the flange portion. Inner member (for example, inner member 52 described later) 62) and a connection holding means for holding the electrical connection between the inner member and the outer member by holding the base portion in contact with the flange portion in a normal state (for example, a later-described engagement member). Driving means (for example, a thermal expansion material to be described later) that generates driving force for sliding the inner member in the axial direction of the cylindrical portion and the pawl 53, the weld layer 73, the positive current collecting lead plate 99). 59, an elastic member 71), and when the battery generates heat, the connection by the connection holding means is released by the driving force generated by the driving means, and the base portion is separated from the flange portion. When the inner member slides, the electrical connection between the inner member and the outer member is limited or blocked.

  In the first invention, a mechanism for limiting or interrupting the current is provided at the terminal which is not easily affected by the pressure in the case. Specifically, a mechanism for limiting or cutting off the charging current and discharging current by increasing the electrical resistance in accordance with the temperature rise of the terminal is provided. This current interruption mechanism has a PTC (self-temperature control) function for changing the electrical resistance by changing the contact area between the inner member and the outer member having the above-described structure according to the temperature. By reducing the contact area, the electrical resistance is increased to limit or block current. The decrease in the contact area between the inner member and the outer member that are in contact with each other in the normal state is that the inner member moves in a direction in which the base portion of the inner member is separated from the flange portion of the outer member by the driving force generated by the driving means due to heat generation of the battery. This is achieved by sliding.

According to the first invention, in a normal state, the connection holding means holds the state in which the protrusion is fitted into the cylindrical portion and the base is in contact with the flange, and the electrical connection between the inner member and the outer member is maintained. Connection is maintained. Here, the normal time means the time except when the battery generates heat.
On the other hand, for example, when overcharging or a short circuit occurs, the battery generates heat and the terminal temperature rises. Then, the driving means generates a driving force, and the generated driving force releases the connection by the connection holding means, and the inner member slides in a direction in which the base portion is separated from the collar portion. The contact area is reduced. As a result, the electrical resistance increases, and the electrical connection between the inner member and the outer member is restricted or interrupted. Therefore, according to the first aspect of the invention, further heat generation can be reliably prevented, and battery deterioration and failure can be avoided.

Further, unlike the conventional mechanism that cuts off the current based on the internal pressure, the current cut-off mechanism of the first invention is driven based on the temperature, so that the pressure in the case rises and the internal pressure is released by a pressure valve or the like. The current can be limited or interrupted even under conditions.
Moreover, since it is not necessary to design the case with high rigidity, the case can be reduced in weight. In addition, since the terminal portion has a hollow structure, the terminal can be reduced in weight, and the battery can be reduced in weight.
In addition, since the current interrupting mechanism is provided in the terminal portion, the space for arranging the storage element is not sacrificed, the case can be downsized, and the battery can be downsized.
Further, for example, when a lead plate is used for connection between the electrode terminal and the electrode, it is not necessary to break the lead plate as in the conventional case, so that the plate thickness of the lead plate can be set large and the electric resistance can be reduced.

  In the second invention, in a normal state, a sealed space (for example, sealed spaces 58 and 68 described later) is formed between the projecting portion and the cylindrical portion, and the connection holding means is connected to the inner side. A locking claw (for example, a locking claw 53 to be described later) that locks a member to the outer member, and the driving means is a thermal expansion material (for example, to be described later) that is enclosed in the sealed space and expands its volume by heat The thermal expansion material 59), and when the battery generates heat, the volume of the thermal expansion material expands, whereby the locking by the locking claw is released and the base portion is separated from the flange portion. When the inner member slides, the electrical connection between the inner member and the outer member is limited or blocked.

In the second invention, the projecting portion is configured so that a sealed space is formed between the projecting portion and the tubular portion in a normal state, and a thermally expandable material as a driving means is enclosed in the sealed space. . Moreover, the latching claw which latches an inner member and an outer member was provided as a connection holding means.
According to the second invention, when the battery generates heat, the expansion force of the thermal expansion material enclosed in the sealed space is used as the driving force for sliding the inner member. Due to the expansion force of the thermal expansion material, the locking by the locking claw is released and the inner member slides in a direction in which the base part is separated from the collar part, thereby limiting the electrical connection between the inner member and the outer member. Or blocked. Therefore, the effect of the first invention is surely achieved.

Further, according to the second invention, a thermal expansion material having a desired expansion start temperature and a desired expansion force can be selected as the thermal expansion material, so that the driving temperature of the current interrupt mechanism can be freely set. For example, the electrical resistance can be gradually increased from around 60 ° C., which is a temperature at which battery performance starts to be affected. If the thermal expansion material enclosed in the sealed space is not discharged into the case, such as when the protrusion is detached from the cylindrical portion, it can be used repeatedly.
Further, in the conventional mechanism that cuts off the current based on the pressure in the case, the case is deformed and the internal pressure varies. On the other hand, according to the second invention, since the thermal expansion material is sealed in the sealed space formed in the high-strength terminal, the expansion force of the thermal expansion material is directly used for driving the inner member to generate the current. Can be restricted or blocked. Therefore, the current can be limited or cut off more reliably and quickly than the conventional case using the pressure in the case.

  In the third invention, the protrusion is a hollow protrusion (for example, a protrusion 522 described later) having an open end, or the protrusion length thereof is shorter than the length of the cylindrical portion. It is a protrusion (for example, the protrusion 622 mentioned later).

In 3rd invention, the protrusion part of the inner member was formed in the hollow shape which the front-end | tip opened. Alternatively, the protrusion length is set shorter than the length of the cylindrical portion.
In the case of a hollow projection having an open end, a sealed space is formed by the hollow portion and the cylindrical portion of the projection. Moreover, in the case of the protrusion which set the protrusion length shorter than the length of a cylindrical part, sealed space is formed by the front-end | tip of this protrusion and a cylindrical part. Therefore, according to the third aspect of the invention, it is possible to reliably ensure a sealed space that encloses the thermal expansion material as the driving means, and the effects of the second aspect of the invention are reliably exhibited.

  In the fourth invention, the projecting portion is formed so that the sealed space communicates with the inside of the case when the inner member slides in a direction in which the base portion is separated from the flange portion, The thermal expansion material includes a fire extinguishing agent, and when the battery generates heat, the volume of the thermal expansion material expands, whereby the connection by the connection holding means is released and the base portion is separated from the flange portion. When the inner member slides, the electrical connection between the inner member and the outer member is restricted or blocked, and the sealed space communicates with the inside of the case so that the fire extinguishing agent is It is introduced in a case.

In the fourth invention, the protrusion is formed so that the sealed space communicates with the inside of the case when the inner member slides in a direction in which the battery generates heat and the base part is separated from the collar part. Moreover, a fire extinguishing agent was contained in the thermal expansion material sealed in the sealed space.
According to the fourth invention, when the inner member slides in the direction in which the base part is separated from the collar part due to the heat generation of the battery and the expansion of the volume of the thermal expansion material, the electrical connection between the inner member and the outer member is achieved. The connection is restricted or cut off, and the sealed space communicates with the inside of the case. Thereby, in addition to the effects of the second and third inventions, the fire extinguisher enclosed in the sealed space is introduced into the case, so that deterioration and failure of the battery can be prevented.
In addition, as a configuration in which the sealed space communicates with the inside of the case when the inner member slides in a direction in which the base portion is separated from the collar portion, for example, the protruding length of the protruding portion is increased by the expansion force of the thermal expansion material. Examples include a configuration in which the protrusion is separated from the cylindrical portion when the inner member slides in a direction in which the base slides away from the collar portion, and is set shorter than the distance that the member slides.

  In a fifth invention, the case includes a pressure valve (for example, a pressure valve 35 described later) for releasing the pressure in the case.

In the fifth invention, a pressure valve is provided for releasing the pressure in the case when the pressure in the case rises.
In the fourth aspect of the present invention, when the battery generates heat, the thermal expansion material and the fire extinguishing agent enclosed in the sealed space are introduced into the case. By introducing these, the pressure in the case increases. Therefore, according to the fifth aspect, the pressure in the case can be released by the pressure valve, so that the case can be prevented from being deformed. Further, since the pressure valve is opened, it is possible to easily determine whether there is an abnormality from the outside.

  In a sixth aspect of the invention, the protrusion is formed so that the protrusion length is shorter than the length of the cylindrical portion, and the connection holding means is a weld layer (for example, described later) that welds the inner member and the outer member. And the drive means is made of a shape memory alloy that is disposed in a sealed space formed by the protrusion and the cylindrical portion and that extends in the axial direction of the cylindrical portion by heat. An elastic member (for example, an elastic member 71 described later), and when the battery generates heat, the elastic member made of the shape memory alloy extends in the axial direction of the cylindrical portion, so that the weld layer breaks. Thus, when the inner member slides in a direction in which the base portion is separated from the flange portion, the electrical connection between the inner member and the outer member is limited or cut off.

In the sixth aspect of the present invention, a protruding portion whose protruding length is shorter than the length of the cylindrical portion is formed, and a weld layer for welding the inner member and the outer member is provided as the connection holding means. In addition, an elastic member made of a shape memory alloy that extends in the axial direction of the tubular portion by heat is provided in the sealed space formed by the protrusion and the tubular portion as the driving means.
According to the sixth invention, the axial extension force of the elastic member made of the shape memory alloy disposed in the sealed space is used as the driving force for sliding the inner member when the battery generates heat. Due to this stretching force, the weld layer breaks and the inner member slides in a direction in which the base portion is separated from the collar portion, thereby restricting or blocking the electrical connection between the inner member and the outer member. The current interruption mechanism according to the sixth aspect of the invention is more reliable because the operation design of the inner member is simpler than the current interruption mechanism according to the second aspect of the invention. Therefore, according to the sixth aspect, the effects of the first aspect are more reliably achieved.

  In the seventh invention, the protrusion is formed so that the protrusion length is shorter than the length of the tubular portion, and the connection holding means electrically connects the base and the one electrode, A lead plate that biases the inner member in a direction in which the base abuts against the flange portion (for example, a positive current collecting lead plate 99 described later), and the driving means includes the protrusion and the cylindrical portion. An elastic member (for example, elastic member 71 described later) made of a shape memory alloy that is disposed in the sealed space formed and extends in the axial direction of the cylindrical portion by heat, and when the battery generates heat, When the elastic member made of a shape memory alloy extends in the axial direction of the cylindrical portion, the inner member slides in a direction in which the base portion is separated from the flange portion against the urging force of the lead plate. The inner member and the outer member Wherein the electrical connection is limited or blocked.

In the seventh invention, the protrusion is formed with a protrusion shorter than the length of the cylindrical portion, and as a connection holding means, the base and one of the electrodes are electrically connected, and the base is connected to the flange. A lead plate for urging the inner member in the abutting direction was provided. In addition, an elastic member made of a shape memory alloy that extends in the axial direction of the tubular portion by heat is provided in the sealed space formed by the protrusion and the tubular portion as the driving means.
According to the seventh invention, the axial extension force of the elastic member made of the shape memory alloy disposed in the sealed space is used as the driving force for sliding the inner member when the battery generates heat. Due to this stretching force, the inner member slides in a direction in which the base part is separated from the collar part against the urging force of the lead plate, thereby restricting or blocking the electrical connection between the inner member and the outer member. The current interruption mechanism in the seventh invention is more reliable because the operation design of the inner member is simpler than the current interruption mechanism in the second invention. Therefore, according to the seventh aspect, the effect of the first aspect is more reliably achieved.
In the seventh aspect of the invention, since the urging force of the lead plate is used as the connection holding means, the elastic member made of the shape memory alloy is once stretched due to the heat generated by the battery, and then the temperature is reduced and reduced. Sometimes, the electrical connection between the inner member and the outer member can be restored by the urging force of the lead plate again. Therefore, the battery according to the seventh invention can be used repeatedly.

  The eighth invention provides a battery module formed by connecting the batteries according to the first to seventh inventions in parallel.

In the eighth invention, a battery module is formed by connecting a plurality of the batteries according to the first to seventh inventions in parallel.
According to the battery module of the eighth aspect of the invention, for example, when a short circuit occurs for some reason, such as the inclusion of foreign matter, the potential of the shorted battery decreases, and a current flows from another parallel battery into the shorted battery. Then, the short-circuited battery generates heat, and the driving means provided at the terminal generates driving force due to this heat. Then, by this driving force, the connection holding means is released and the inner member slides in the direction in which the base part is separated from the collar part, thereby restricting or blocking the electrical connection between the inner member and the outer member. Therefore, according to the battery module of the eighth invention, further heat generation can be reliably prevented, and deterioration or failure of the battery due to heat generation can be avoided.
As described above, since the batteries according to the first to seventh inventions can be reduced in size and weight, the effect of the battery module according to the eighth invention using these batteries is achieved. Is further enhanced.

  ADVANTAGE OF THE INVENTION According to this invention, the battery and battery module which can restrict | limit or interrupt | block current reliably and can prevent a deterioration and failure of a battery can be provided without using the electric current interruption mechanism using the internal pressure of a cell or a fuse.

It is a front view of the lithium ion secondary battery which concerns on 1st Embodiment. It is a right view of the lithium ion secondary battery which concerns on 1st Embodiment. It is a fragmentary sectional view of the positive electrode terminal in the normal time of the lithium ion secondary battery which concerns on 1st Embodiment. It is a figure for demonstrating the manufacturing method of the positive electrode terminal of the lithium ion secondary battery which concerns on 1st Embodiment, (A) is a figure which shows the process of forming an outer member, (B) is cylindrical. It is a figure which shows the process of inject | pouring DMC into a part, (C) is a figure which shows the process of inserting and inserting the protrusion of an inner member in the cylindrical part of an outer member, (D) is a latching nail | claw. It is a figure which shows the process of latching an inner member to an outer member by. It is a fragmentary sectional view of the positive electrode terminal at the time of heat_generation | fever of the lithium ion secondary battery which concerns on 1st Embodiment. It is a fragmentary sectional view of the positive electrode terminal in the normal time of the lithium ion secondary battery which concerns on 2nd Embodiment. It is a fragmentary sectional view of the positive electrode terminal at the time of heat_generation | fever of the lithium ion secondary battery which concerns on 2nd Embodiment. It is a fragmentary sectional view of the positive electrode terminal in the normal time of the lithium ion secondary battery which concerns on 3rd Embodiment. It is a fragmentary sectional view of the positive electrode terminal in the normal time of the lithium ion secondary battery which concerns on 4th Embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that in the description of the second and subsequent embodiments, the same reference numerals as those in the first embodiment are assigned to configurations common to the first embodiment, and the description thereof is omitted.

<First Embodiment>
FIG. 1 is a front view of the lithium ion secondary battery 1 according to the first embodiment, and FIG. 2 is a right side view of the lithium ion secondary battery 1.
As shown in FIGS. 1 and 2, the lithium ion secondary battery 1 is a secondary battery having a thin plate shape and a rectangular outer shape. For example, a plurality of lithium ion secondary batteries 1 are connected in parallel to constitute a high voltage battery. Moreover, the high voltage battery comprised in this way is used as a storage battery of an electric vehicle or a hybrid vehicle.

  As shown in FIGS. 1 and 2, the lithium ion secondary battery 1 includes a storage element 10, an electrolyte solution (not shown), a case 30, a positive terminal 50, a negative terminal 100, and a positive current collecting lead plate 95. And a negative electrode current collecting lead plate 97.

[Storage element]
The power storage element 10 includes a power storage element body 11, a positive current collector tab 15, and a negative current collector tab 17.
The storage element 10 is formed, for example, with a length (dimension in the horizontal direction in FIG. 1) of 147 mm, a width of 80 mm (dimension in the vertical direction in FIG. 1), and a thickness (dimension in the horizontal direction in FIG. 2) of 38 mm. The

The power storage element body 11 is configured by a laminate in which positive electrode sheets and negative electrode sheets are alternately stacked via insulating separators. Moreover, the positive electrode current collection tab 15 is comprised by the laminated body of the positive electrode sheet, and the negative electrode current collection tab 17 is comprised by the laminated body of the negative electrode sheet.
The positive electrode current collecting tab 15 constitutes the positive electrode of the lithium ion secondary battery 1, and the negative electrode current collecting tab 17 constitutes the negative electrode of the lithium ion secondary battery 1.

A positive electrode sheet is comprised including the positive electrode current collection foil which has electroconductivity, and the positive electrode active material layer each formed in both surfaces of the positive electrode current collection foil. As the positive electrode current collector foil, for example, a rectangular aluminum foil (for example, a thickness of 12 μm) is used.
The positive electrode active material layer is formed by applying a mixture of a positive electrode active material, a conductive filler, and a binder (adhesive) to the positive electrode current collector foil, excluding one end in the length direction, and then pressing the mixture. It is formed. The uncoated portion is wound to constitute the positive electrode current collecting tab 15.
For example, the length of the coated part is 131 mm, the length of the uncoated part is 7 mm, the thickness of the positive electrode sheet after pressing is 100 μm, and the electrode density of the positive electrode sheet is 3.8 g / cm ^3. The

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 is used.
As the conductive filler, for example, acetylene black, ketjen black, or VCGF (vapor growth carbon fiber) is used.
As the binder, for example, PVDF (polyvinylidene difluoride) is used.

A negative electrode sheet is comprised including the negative electrode current collection foil which has electroconductivity, and the negative electrode active material layer each formed in both surfaces of the negative electrode current collection foil. As the negative electrode current collector foil, for example, a rectangular copper foil (for example, a thickness of 10 μm) is used.
The negative electrode active material layer is formed by coating a mixture of a negative electrode active material and a binder (adhesive) on the negative electrode current collector foil, excluding one end side in the length direction, and then pressing. The uncoated portion is wound to constitute the negative electrode current collecting tab 17.
In the negative electrode sheet, for example, the length of the coated part is 133 mm, the length of the uncoated part is 7 mm, the thickness of the negative electrode sheet after pressing is 100 μm, and the electrode density of the negative electrode sheet is 1.5 g / cm ^3. Formed as follows.

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) is used.
As the carbon material, for example, natural graphite, artificial graphite (for example, particle size 22 μm), activated carbon, low-temperature carbon body (organic precursor) heat-treated in an inert gas atmosphere, or the like is used. Examples of the low-temperature carbon body (organic precursor) 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. The body is used.
For example, PVDF is used as the binder.

  The separator electrically insulates the positive electrode sheet and the negative electrode sheet. The separator is formed of a porous body and is impregnated in an electrolyte solution described later filled in the case 30. As the separator, for example, a polyolefin-based porous separator such as polyethylene or polypropylene, or a nonwoven fabric made of polyester fiber or aramid fiber is used. The separator is formed with a thickness of 25 μm, for example.

Next, the manufacturing method of the electrical storage element 10 is demonstrated.
The electrical storage element 10 is obtained by winding a laminated body obtained by alternately laminating positive electrode sheets and negative electrode sheets with separators around a plate-shaped core, and then pulling out the core. More specifically, the electricity storage device 10 shifts the positive electrode sheet and the negative electrode sheet in the surface direction by an amount corresponding to each uncoated part so that only the respective coated parts overlap each other, and on one end side in the length direction. Laminate so that only the uncoated part of the positive electrode sheet is disposed and only the uncoated part of the negative electrode sheet is disposed on the other end side, and winding is performed so that the negative electrode sheet is outside the positive electrode sheet. To do. After obtaining the wound body, the storage element body 11 in which the coated portions of the positive electrode sheet and the negative electrode sheet are laminated at the center in the length direction by crushing in the thickness direction so that the cross-section of the ring becomes flat. Is formed.
Moreover, the positive electrode current collection tab 15 and the negative electrode current collection tab 17 are formed by making the uncoated part of the positive electrode sheet and negative electrode sheet in the both ends of a length direction closely_contact | adhere by thickness etc. by welding.
As described above, the power storage element 10 including the power storage element body 11, the positive electrode current collecting tab 15, and the negative electrode current collecting tab 17 is formed.

  In addition, the electrical storage element 10 provided with the above configuration is covered with an insulating film (not shown) and is electrically insulated from the case 30. For example, a polyethylene film or a polypropylene film is used as the insulating film.

[Electrolyte]
An electrolyte solution (not shown) is filled in the case 30, and the power storage element 10 is immersed in the electrolyte solution. The electrolyte transports ions such as lithium ions generated by the battery reaction between both electrodes. The electrolytic solution is prepared by dissolving an electrolyte in a solvent.

  A non-aqueous solvent is used as the solvent. Examples of the non-aqueous solvent include 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. These nonaqueous 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 ] are used. In addition, it is preferable that the dissolution amount with respect to the nonaqueous solvent of electrolyte is 0.2 mol / L-2 mol / L.

Moreover, you may add and mix LiTFSI (lithium salt) etc. in electrolyte solution.
Furthermore, a gel electrolyte may be used so that the electrolyte is held in a gel form. As the gel electrolyte, for example, polyethylene oxide, polypropylene oxide, vinylidene fluoride, a derivative of hexafluoropropylene, or a copolymer thereof is used.

[Case]
As shown in FIGS. 1 and 2, the case 30 has a thin plate shape and a rectangular outer shape. Case 30 houses and holds power storage element 10. The case 30 includes a case main body 31 and a lid 33.

  The case main body 31 is a thin plate-like box having an upper surface opened. The case body 31 is made of an aluminum alloy, SUS (stainless steel), resin, or the like. In particular, those made of an aluminum alloy and formed by impact molding or transfer press processing are preferably used. The case body 31 has, for example, a plate thickness of 1.0 mm, a length (dimension in the horizontal direction in FIG. 1) of 155 mm, a width (dimension in the horizontal direction in FIG. 2) and a height (vertical direction in FIG. 1). (Dimension) is formed with an outer dimension of 100 mm.

The lid 33 has a predetermined thickness (for example, 2 mm) and closes the opening of the case body 31. The lid 33 is joined to the case body 31 by, for example, laser welding.
The lid 33 is provided with an injection port (not shown) for injecting an electrolytic solution.

[Terminal]
The positive electrode terminal 50 and the negative electrode terminal 100 are attached to both ends of the lid 33 in the longitudinal direction. The positive electrode terminal 50 and the negative electrode terminal 100 are formed of a metal such as copper, nickel, aluminum, SUS (stainless steel), or an alloy made of these metals.

  The positive electrode terminal 50 is electrically connected to the positive electrode current collecting tab 15 of the power storage element 10 via the positive electrode current collecting lead plate 95. The positive electrode current collecting lead plate 95 is formed of, for example, an aluminum alloy plate having a width of 40 mm and a thickness of 0.5 mm. The positive electrode current collecting tab 15 and the positive electrode terminal 50 are electrically connected to the positive electrode current collecting lead plate 95, for example, by ultrasonic welding.

  The negative electrode terminal 100 is electrically connected to the negative electrode current collecting tab 17 of the power storage element 10 via the negative electrode current collecting lead plate 97. The negative electrode current collector lead plate 97 is formed of, for example, a copper alloy plate having a width of 45 mm and a thickness of 0.3 mm. The negative electrode current collecting tab 17 and the negative electrode terminal 100 are electrically connected to the negative electrode current collecting lead plate 97, for example, by ultrasonic welding.

The positive current collecting lead plate 95 and the negative current collecting lead plate 97 are reverse L-shaped lead plates having conductivity. These lead plates have a long portion connected to each current collecting tab and a short portion connected to each terminal.
The electrical resistance can be reduced by sufficiently securing the contact area between the positive electrode current collector lead plate 95 and the positive electrode current collector tab 15 and the contact area between the negative electrode current collector lead plate 97 and the negative electrode current collector tab 17. Is preferred.

  Here, the positive electrode terminal 50 constitutes a mechanism (hereinafter referred to as a current interruption mechanism) that limits or cuts off the current when the lithium ion secondary battery 1 generates heat. Hereinafter, a current interruption mechanism including the positive electrode terminal 50 will be described with reference to FIG.

  FIG. 3 is a partial cross-sectional view of the positive electrode terminal 50 at the normal time of the lithium ion secondary battery 1, specifically, at the time of discharging when a plurality of the lithium ion secondary batteries 1 are connected in parallel to constitute a high voltage battery. As shown in FIG. 3, the positive terminal 50 includes an outer member 51, an inner member 52, and locking claws 53 and 53.

The outer member 51 includes a cylindrical portion 511 having one end closed and the other end opened, and a flange portion 512 extending radially outward from the opening end of the cylindrical portion 511.
The outer member 51 is fixed to the lid 33 of the case 30 in a state where the closed end side of the cylindrical portion 511 is disposed outside the case 30 and the open end side of the cylindrical portion 511 is disposed inside the case 30. . Specifically, the cylindrical portion 511 is fitted into a hole provided in the lid 33 of the case 30 and is fixed in a state where the upper surface on the closed end side of the flange portion 512 is in contact with the lower surface of the lid 33. . A bolt groove (not shown) is cut on the outer peripheral surface of the outer member 51, and a nut 54 and a washer 55 are used to fix the outer member 51.

  The cylindrical part 511 is cylindrical, and its axial direction is perpendicular to the upper and lower surfaces of the lid 33 of the case 30. Further, a protrusion 522 of an inner member 52 described later is slidably fitted into the hollow portion.

  The flange portion 512 is provided over the entire circumference of the opening of the cylindrical portion 511, and the extending direction of the flange portion 512 is parallel to the lower surface of the lid 33. The upper surface, which is the surface on the closed end side of the flange portion 512, is in contact with the lower surface of the lid 33, and the lower surface of the flange portion 512 is in contact with a base portion 521 of an inner member 52 to be described later.

An annular resin sealing member 57 having flanges at the upper and lower ends is disposed between the outer member 51 and the lid 33 in order to ensure insulation and sealing properties.
Further, an external cable 56 is electrically connected to the outer member 51, and the external cable 56 is fixed to the outer member 51 by a nut 54 and a washer 55.

The inner member 52 includes a base portion 521 that is electrically connected to the positive electrode current collector lead plate 95, and a protrusion portion 522 that protrudes from the base portion 521 and is slidably fitted into the cylindrical portion 511.
The inner member 52 is normally locked to the outer member 51 by locking claws 53 and 53, which will be described later, with the upper surface of the base portion 521 being in contact with the lower surface of the flange portion 512.

The base portion 521 has a disc shape, and the radial direction thereof is parallel to the lower surface of the flange portion 512 of the outer member 51. The upper surface of the base portion 521 is in contact with the lower surface of the flange portion 512 of the outer member 51 in a normal state. The diameter of the base portion 521 is set to be approximately equal to the diameter of the flange portion 512 from the viewpoint of ensuring a sufficient contact area with the flange portion 512 and reducing the electric resistance. Further, the lower surface of the base 521 is electrically connected to the positive electrode current collector lead plate 95 with a sufficient contact area.
Note that a locking groove (not shown) into which locking claws 53 and 53 described later are inserted is provided on the outer periphery of the base 521.

  The protrusion 522 is formed in a hollow cylindrical shape whose opening is opened at the tip and closed at the base. The tip of the protrusion 522 reaches and contacts the closed end surface of the outer member 51, and a sealed space 58 is formed by the hollow portion of the protrusion 522 and the closed end surface of the tubular portion 511. In this sealed space 58, a thermal expansion material 59 whose volume is expanded by heat is enclosed. The thermal expansion material 59 will be described in detail later.

  The locking claws 53, 53 normally lock the inner member 52 to the outer member 51 with the upper surface of the base 521 of the inner member 52 being in contact with the lower surface of the flange portion 512 of the outer member 51. To do. The locking claws 53, 53 are attached to the outer periphery of the flange portion 512 of the outer member 51 at equal intervals, and are inserted into locking grooves (not shown) provided evenly on the outer periphery of the base portion 521 of the inner member 52, respectively. The inner member 52 is locked by engaging a claw with the lower surface of the base 521.

Due to the locking by the locking claws 53, 53, the electrical connection between the inner member 52 and the outer member 51 is maintained. When the lithium ion secondary battery 1 generates heat, the locking claws 53 and 53 are slid in the direction in which the base portion 521 is separated from the flange portion 512 (downward in FIG. 1) by the expansion force of the thermal expansion material 59. To deform and release the lock.
In addition, in order to ensure insulation, the latching claws 53 and 53 are formed from insulating members, such as resin.

Next, the thermal expansion material 59 will be described.
As the thermal expansion material 59, any material that expands in volume as the temperature increases and can slide the inner member 52 can be used, and any of gas, liquid, and solid can be used. These thermal expansion materials 59 may be used alone or in combination. The thermal expansion material 59 includes a material in which a solid or liquid is vaporized to generate a gas, or a volume that expands by generating a gas by a reaction.

  As the gaseous thermal expansion material, incombustible gas or flame retardant gas is preferably used. Specific examples include nitrogen, argon, and carbon dioxide. Among these, carbon dioxide is particularly preferably used.

As the liquid thermal expansion material, a compound having a low boiling point and a low ignition point or a compound having high thermal stability is preferably used. More preferably, a low boiling point and flame retardant compound is used.
The liquid thermal expansion material is easier to enclose in the sealed space 58 than the gaseous thermal expansion material, as will be described later. For this reason, when a liquid thermal expansion material is used, productivity is high and manufacturing cost can be reduced.

Examples of compounds having a low boiling point and a low ignition point include carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate ( In addition to compounds such as EMC), these carboxylic acid ester derivatives, these fluorine compounds and chlorine compounds can be mentioned.
Examples of the compound having a low boiling point and high thermal stability include carboxylic acid esters.

Examples of the low boiling point and flame retardant compounds include fluorine compounds, chlorine compounds, bromine compounds, and phosphate esters.
Conventionally, fluorine compounds have been used as a flame retardant for electrolytic solutions. However, when a certain amount or more is added to the electrolytic solution, the degree of dissociation of the Li salt decreases, and the internal resistance increases particularly at low temperatures. was there. In this respect, in the present embodiment, since the low boiling point and flame retardant compound is introduced into the case 30 for the first time when heat is generated, the conventional problem does not occur.

As the solid thermal expansion material, both inorganic compounds and organic compounds can be used. In particular, a solid thermal expansion material is preferably used because it is easier to enclose in the sealed space 58 than the liquid thermal expansion material.
Examples of inorganic compounds include alkali metal carbonates such as Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ and NaHCO ₃ . These alkali metal carbonates generate carbon dioxide by thermal decomposition, thereby expanding the volume and sliding the inner member.
Examples of the organic compound include foaming compounds such as dinitrosopentamethylenetetramine, azodicarbonamide and p, p′-oxybisbenzenesulfonylhydrazide, and compounds having a high freezing point such as organic liquid sulfolane and derivatives thereof.

  For the purpose of improving the thermal conductivity, the above-described gas, liquid and solid thermal expansion materials may be mixed with a metal such as Cu or Al having a high thermal conductivity or a solid powder such as alumina. Thereby, the thermal conductivity of the thermal expansion material 59 is improved, and the expansion of the volume is promoted.

  Even when the driving temperature of the inner member 52 is 100 ° C. or higher, the electrolyte in the case 30 is not vaporized and the pressure in the case 30 does not increase. At this time, the volume of the thermal expansion material 59 enclosed in the sealed space 58 in the positive electrode terminal 50 expands, and the inner member 52 slides at a pressure of 0.1 to 0.6 MPa, for example.

Next, a method for manufacturing the positive terminal 50 will be described with reference to FIG.
First, as shown in FIG. 4A, the disk-shaped member to which the locking claws 53 and 53 are attached and the columnar member in which a bolt groove (not shown) is cut on the outer periphery are coaxial in the axial direction. The precursor 51a of the outer member 51 connected as follows is prepared. Next, the outer member 51 including the cylindrical portion 511 and the flange portion 512 is formed by drilling in the center of the precursor 51a after drilling from the disk-shaped member side. For example, the hollow part of the cylindrical part 511 is formed as a hollow part having a diameter of 5 mm and an axial length of 8 mm.

  Next, as shown in FIG. 4B, a predetermined amount of dimethyl carbonate (DMC), for example, is injected into the hollow portion of the cylindrical portion 511 as the thermal expansion material 59. At this time, the amount of the thermal expansion material 59 is appropriately set according to the type of the thermal expansion material 59 in consideration of the drive setting temperature of the current interrupt mechanism.

Next, as shown in FIG. 4C, the protrusion 522 of the inner member 52 is inserted into the cylindrical portion 511 into which the DMC of the thermal expansion material 59 has been injected. At this time, the locking claws 53 are inserted into the locking grooves 523 provided evenly on the outer periphery of the base 521.
The protrusion 522 of the inner member 52 has a hollow cylindrical shape with an open end, and the inner member 52 is formed in the same manner as the outer member 51 described above. For example, the hollow portion of the protrusion 522 is formed as a hollow portion having a diameter of 4 mm and an axial length of 7 mm.

Next, as shown in FIG. 4D, the protrusion 522 is fitted into the cylindrical portion 511 until the base 521 contacts the flange 512, and the claws of the locking claws 53 and 53 are engaged with the base 521. Thus, the inner member 52 is locked to the outer member 51. As a result, a sealed space 58 surrounded by the hollow portion of the protrusion 522 and the closed end surface of the cylindrical portion 511 is formed, and the thermal expansion material 59 is enclosed in the formed sealed space 58.
Thus, the positive electrode terminal 50 is obtained.

About the lithium ion secondary battery 1 provided with the positive electrode terminal 50 manufactured according to said manufacturing method, the operation confirmation test has been implemented and the operation | movement is confirmed.
Specifically, CCCV (constant current constant voltage) charging was performed at 4.2 V in a thermostatic chamber, and the temperature was increased from 25 ° C. at a rate of 5 ° C./min. It has been confirmed that the resistance rises and the terminal voltage becomes 0 V at 85 ° C. Further, when the inside was disassembled, it was also confirmed that the locking by the locking claws 53, 53 was released, and the base portion 521 of the inner member 52 and the flange portion 512 of the outer member 51 were separated. .
As described above, the positive electrode terminal 50 manufactured according to the above manufacturing method functions as a current interrupting mechanism that limits or interrupts the current when the lithium ion secondary battery 1 generates heat.

Next, the effects obtained when the lithium ion secondary battery 1 according to the present embodiment generates heat will be described with reference to FIGS. 4 and 5. FIG. 5 is a partial cross-sectional view of the positive electrode terminal 50 when the lithium ion secondary battery 1 generates heat.
In the present embodiment, a mechanism for limiting or blocking current is provided on the positive electrode terminal 50 that is not easily affected by the pressure in the case 30. Specifically, a mechanism for limiting or cutting off the charging current and discharging current by increasing the electrical resistance according to the temperature rise of the positive electrode terminal 50 is provided. This current interruption mechanism has a PTC (self-temperature control) function for changing the electrical resistance by changing the contact area between the inner member 52 and the outer member 51 according to the temperature, and the contact between the inner member 52 and the outer member 51. By reducing the area, the electrical resistance is increased to limit or block the current. The decrease in the contact area between the inner member 52 and the outer member 51 that are in contact with each other at normal times is caused by the expansion force of the thermal expansion material 59 generated by the heat generation of the battery, and the base portion 521 of the inner member 52 is the flange portion 512 of the outer member 51. This is achieved by sliding the inner member 52 in a direction away from the inner member 52.

In the present embodiment, as shown in FIG. 4, in a normal state, the protrusions 522 are fitted and inserted into the cylindrical portion 511 by the locking claws 53 and 53, and the base portion 521 is in contact with the flange portion 512. Retained. Thereby, as shown by the arrow in FIG. 4, the electrical connection between the inner member 52 and the outer member 51 is maintained, and current flows into the storage element 10.
On the other hand, as shown in FIG. 5, for example, when a short circuit occurs for some reason during discharging, current flows from another parallel battery, the lithium ion secondary battery 1 generates heat, and the temperature of the positive electrode terminal 50 rises. To do. Then, the volume of the thermal expansion material 59 enclosed in the sealed space 58 expands, and this expansion force releases the connection by the locking claws 53, 53 as shown by the white arrows in FIG. As the inner member 52 slides in the direction away from 512, the contact area between the inner member 52 and the outer member 51 decreases. As a result, the electrical resistance increases, and the electrical connection between the inner member 52 and the outer member 51 is restricted or interrupted as indicated by the black arrow in FIG. Therefore, according to the present embodiment, further heat generation can be reliably prevented, and deterioration or failure of the lithium ion secondary battery 1 can be avoided.

In addition, unlike the conventional mechanism that cuts off the current based on the internal pressure, the current cut-off mechanism of the present embodiment is driven based on the temperature, so that the pressure in the case 30 increases and the internal pressure is released by a pressure valve or the like. The current can be limited or interrupted even under conditions.
Moreover, since it is not necessary to design the case 30 with high rigidity, the case 30 can be reduced in weight. In addition, since the positive electrode terminal 50 has a hollow structure, the positive electrode terminal 50 can be reduced in weight, and the lithium ion secondary battery 1 can be reduced in weight.
Moreover, since the current interruption mechanism is provided in the positive electrode terminal 50, the arrangement space of the power storage element 10 is not sacrificed, the case 30 can be miniaturized, and the lithium ion secondary battery 1 can be miniaturized.
Further, since there is no need to break the lead plate as in the prior art, the plate thickness of the positive electrode current collecting lead plate 95 used for connection between the positive electrode terminal 50 and the positive electrode current collecting tab 15 can be set large, and the electric resistance can be reduced. .

Moreover, in this embodiment, since the thermal expansion material which has desired expansion start temperature and desired expansion force can be selected as the thermal expansion material 59, the drive temperature of an electric current interruption mechanism can be set freely. For example, the electrical resistance can be gradually increased from around 60 ° C., which is a temperature at which the performance of the lithium ion secondary battery 1 starts to be affected. If the thermal expansion material 59 enclosed in the sealed space 58 is not discharged into the case 30 such that the protrusion 522 is detached from the cylindrical portion 511, it can be used repeatedly.
Moreover, in the conventional mechanism which interrupts | blocks an electric current based on the pressure in the case 30, when the case 30 deform | transforms and an internal pressure varies, there was difficulty in certainty and quickness. On the other hand, according to the present embodiment, the thermal expansion material 59 is sealed in the sealed space 58 formed in the high-strength positive electrode terminal 50, so that the expansion force of the thermal expansion material 59 is directly applied to the driving of the inner member 52. It can be used to limit or cut off current. Therefore, the current can be limited or cut off more reliably and quickly than the conventional case using the pressure in the case.

Second Embodiment
The lithium ion secondary battery 2 according to the second embodiment is the same as that of the first embodiment except that the inner member 62 constituting the positive electrode terminal 60 and the lid 36 constituting the case 30 are different from the first embodiment. It is the same composition as.

  FIG. 6 is a partial cross-sectional view of the positive electrode terminal 60 during normal operation of the lithium ion secondary battery 2 according to the second embodiment, specifically, when a high voltage battery is configured by connecting a plurality of them in parallel. is there. As shown in FIG. 6, the inner member 62 includes a base 621 that is electrically connected to the positive electrode current collector lead plate 95, and a protrusion 622 that protrudes from the base 621 and is slidably fitted into the tubular portion 511. And comprising. In the normal state, the inner member 62 is locked to the outer member 51 by the locking claws 53, 53 with the upper surface of the base portion 621 being in contact with the lower surface of the flange portion 512.

The base portion 621 has a disc shape, and the radial direction thereof is parallel to the lower surface of the flange portion 512 of the outer member 51. The upper surface of the base portion 621 is in contact with the lower surface of the flange portion 512 of the outer member 51 in a normal state. The diameter of the base portion 621 is set to be approximately equal to the diameter of the flange portion 512 from the viewpoint of ensuring a sufficient contact area with the flange portion 512 and reducing the electric resistance. Further, the lower surface of the base 621 is electrically connected to the positive electrode current collector lead plate 95 with a sufficient contact area.
Note that a locking groove (not shown) into which locking claws 53 and 53 described later are inserted is provided on the outer periphery of the base 621.

The protruding portion 622 is formed in a columnar shape whose protruding length is shorter than the length of the cylindrical portion 511. The protruding length of the protrusion 622 is set to be shorter than the distance that the inner member 62 slides due to the expansion force of the thermal expansion material 59, and the inner member 62 slides in the direction in which the base 621 is separated from the flange 512. In this case, the protrusion 622 is formed so as to be detached from the cylindrical portion 511.
In addition, since the front end surface of the protrusion 622 does not reach the closed end surface of the cylindrical portion 511, a sealed space 68 is formed by the protrusion 622 and the cylindrical portion 511.
In this sealed space 68, a thermal expansion material 59 whose volume is expanded by heat is enclosed. In the present embodiment, a fire extinguishing agent is also enclosed in the sealed space 68.
As the fire extinguisher, for example, carbon dioxide is used.

  The lid 36 of the case 30 is obtained by providing a pressure valve 35 on the upper surface of the lid 33 of the first embodiment. The pressure valve 35 is a rupture valve (gas vent valve) for releasing the pressure in the case 30, and the opening pressure is set to 0.5 to 1.0 MPa, for example.

Next, the effects obtained when the lithium ion secondary battery 2 according to this embodiment generates heat will be described with reference to FIGS. 6 and 7. FIG. 7 is a partial cross-sectional view of the positive electrode terminal 60 when the lithium ion secondary battery 2 generates heat.
According to the present embodiment, as shown in FIG. 6, in a normal state, the projection 622 is fitted into the cylindrical portion 511 and the base portion 621 contacts the flange portion 512 by the locking claws 53 and 53. State is maintained. Thereby, as shown by the arrow in FIG. 6, the electrical connection between the inner member 62 and the outer member 51 is maintained, and current flows into the storage element 10.
On the other hand, as shown in FIG. 7, for example, when a short circuit occurs for some reason during discharging, current flows from another parallel battery, the lithium ion secondary battery 2 generates heat, and the temperature of the positive electrode terminal 60 rises. To do. Then, the volume of the thermal expansion material 59 enclosed in the sealed space 68 expands, and this expansion force releases the connection by the locking claws 53, 53 as shown by the white arrows in FIG. The inner member 62 slides in a direction away from 512. At this time, in this embodiment, since the protrusion length of the protrusion 622 is set to be shorter than the distance that the inner member 62 slides, the protrusion 622 is separated from the tubular portion 511 as shown in FIG. break away. Thereby, as shown by the black thin arrows in FIG. 7, the electrical connection between the inner member 62 and the outer member 51 is limited or cut off. Therefore, according to the present embodiment, the same effects as those of the first embodiment are achieved.

In the present embodiment, the protruding portion 622 is detached from the cylindrical portion 511, whereby the sealed space 68 is opened and communicates with the inside of the case 30. As a result, as shown by thick black arrows in FIG. 7, the fire extinguishing agent enclosed in the sealed space 68 is introduced into the case 30, so that deterioration or failure of the lithium ion secondary battery 2 can be prevented.
In addition, since the thermal expansion material 59 and the fire extinguishing agent enclosed in the sealed space 68 are introduced into the case 30, the pressure in the case 30 rises. The pressure inside can be released. For this reason, deformation of the case 30 can be prevented, and the presence or absence of abnormality can be easily determined from the outside because the pressure valve 35 is opened.

<Third Embodiment>
In the lithium ion secondary battery 3 according to the third embodiment, an elastic member 71 made of a shape memory alloy is provided as a driving means constituting the positive electrode terminal 70, and instead of the locking claws 53, 53. The second embodiment is the same as the second embodiment except that the weld layer 73 is provided on the surface of the positive electrode current collector lead plate 98 and that the dimensional shape of the positive electrode current collector lead plate 98 is changed.

FIG. 8 is a partial cross-sectional view of the positive electrode terminal 70 at the time of discharging when the lithium ion secondary battery 3 according to the third embodiment is normal, specifically, when a high voltage battery is configured by connecting a plurality of them in parallel. is there. As shown in FIG. 8, the elastic member 71 made of a shape memory alloy is disposed in a sealed space 68 formed by the protrusion 622 of the inner member 62 and the cylindrical portion 511 of the outer member 51.
The elastic member 71 is a spring made of a shape memory alloy and extends in the axial direction of the cylindrical portion 511 by heat.
As the shape memory alloy, for example, an alloy containing any one of Ni, Ti, Cu, and Fe is used. The elastic member 71 made of these shape memory alloys is soft (weak) at low temperatures and hard (strong) at high temperatures. For this reason, since there is a large difference between the load at low temperature (generated force) and the load at high temperature, by utilizing the load difference due to this temperature difference, the weld layer 73 described later is broken to form the inner member 62. Can be slid. That is, the shape memory alloy spring functions as a temperature sensor and an actuator.
Since the shape deformation temperature AF point of the shape memory alloy is in the range of 50 ° C. to 150 ° C., this embodiment is suitable when the drive temperature of the current interrupt mechanism is to be set within this temperature range.
Further, the length of the short portion 98b of the positive electrode current collector lead plate 98 is formed longer because of the relationship in which the welded layer 73 and the elastic member 71 made of a shape memory alloy are provided.

  The weld layer 73 is formed by performing projection welding of the upper surface of the base portion 621 constituting the inner member 62 and the lower surface of the flange portion 512 constituting the outer member 51. Specifically, the weld layer 73 is formed by applying pressure after heating the upper surface of the base portion 621 and the lower surface of the flange portion 512. Due to the weld layer 73, the inner member 62 is in contact with and electrically connected to the outer member 51 via the weld layer 73 in a normal state.

Next, the operational effects achieved when the lithium ion secondary battery 3 according to this embodiment generates heat will be described.
According to the present embodiment, in a normal state, the weld layer 73 maintains the state in which the protrusion 622 is fitted into the cylindrical portion 511 and the base 621 is in contact with the flange portion 512 via the weld layer 73. The Thereby, the electrical connection between the inner member 62 and the outer member 51 is maintained, and current flows into the power storage element 10.
On the other hand, for example, when a short circuit occurs for some reason during discharging, current flows from another parallel battery, the lithium ion secondary battery 3 generates heat, and the temperature of the positive electrode terminal 70 rises. Then, the elastic member 71 made of a shape memory alloy disposed in the sealed space 68 expands in the axial direction of the cylindrical portion 511, and by this expansion force, the weld layer 73 is broken and the base portion 621 is removed from the flange portion 512. The inner member 62 slides in the separating direction. Thereby, the electrical connection between the inner member 62 and the outer member 51 is restricted or blocked. Therefore, according to the present embodiment, further heat generation can be reliably prevented, and deterioration or failure of the lithium ion secondary battery 3 can be avoided.
In addition, the current cut-off mechanism in the present embodiment is simpler and more reliable in the operation design of the inner member 62 than the current cut-off mechanisms in the first embodiment and the second embodiment.

<Fourth embodiment>
The lithium ion secondary battery 4 according to the fourth embodiment is different from the third embodiment in that the weld layer 73 is not provided and the positive electrode current collector lead plate 99 is changed in its shape to maintain the connection. The configuration is the same as that of the third embodiment except that it is formed so as to serve as both.

FIG. 9 is a partial cross-sectional view of the positive electrode terminal 80 at the time of discharging when the lithium ion secondary battery 4 according to the fourth embodiment is in a normal state, specifically, when a high voltage battery is configured by connecting a plurality of them in parallel. is there. As shown in FIG. 9, the positive electrode current collecting lead plate 99 includes a long portion 99 a and a short portion 99 b, and the base member 621 is in contact with the flange portion 512 in the direction in which the inner member 62 is abutted (upward in FIG. 9). Is energized.
The upper end of the longitudinal portion 99 a extends upward from the lower surface of the base portion 621. The short part 99b is composed of a horizontal part that comes into contact with the lower surface of the base part 621, and an inclined part that inclines downward as it approaches the base part 621 from the upper end of the long part 99a and is connected to the horizontal part. It is formed as a piece. The inner member 62 is biased in a direction (upward in FIG. 9) in which the base portion 621 contacts the flange portion 512 by the elastic force of the elastic piece.

Next, functions and effects achieved when the lithium ion secondary battery 4 according to the present embodiment generates heat will be described.
According to the present embodiment, in a normal state, the positive electrode current collecting lead plate 99 holds the state where the protrusion 622 is fitted into the cylindrical portion 511 and the base portion 621 is in contact with the flange portion 512. Thereby, the electrical connection between the inner member 62 and the outer member 51 is maintained, and current flows into the power storage element 10.
On the other hand, for example, when a short circuit occurs for some reason during discharging, the lithium ion secondary battery 4 generates heat and the temperature of the positive electrode terminal 80 rises. Then, the elastic member 71 made of a shape memory alloy disposed in the sealed space 68 expands in the axial direction of the cylindrical portion 511, and the base portion opposes the urging force of the positive electrode current collector lead plate 99 by this expansion force. The inner member 62 slides in a direction in which 621 is separated from the flange portion 512. Thereby, the electrical connection between the inner member 62 and the outer member 51 is restricted or blocked. Therefore, according to this embodiment, further heat generation can be reliably prevented, and deterioration or failure of the lithium ion secondary battery 4 can be avoided.

  In this embodiment, since the biasing force of the positive electrode current collector lead plate 99 is used as the connection holding means, the elastic member 71 made of the shape memory alloy is temporarily expanded by the heat generated by the lithium ion secondary battery 4. Later, when the temperature is reduced and reduced, the electrical connection between the inner member 62 and the outer member 51 can be restored by the biasing force of the positive electrode current collector lead plate 99 again. Therefore, the lithium ion secondary battery 4 of this embodiment can be used repeatedly.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications and improvements within the scope that can achieve the object of the present invention are included in the present invention.
For example, in any of the above embodiments, the current interruption mechanism is provided only on the positive electrode terminal, but the present invention is not limited to this. For example, you may provide only in a negative electrode terminal and may provide in both a positive electrode terminal and a negative electrode terminal.
In the first embodiment and the second embodiment, the positive electrode terminal and the positive electrode current collecting tab are connected via the positive electrode current collecting lead plate, but the present invention is not limited to this. For example, the positive terminal and the positive current collecting tab may be directly connected.
In the second embodiment, the projecting length of the projecting portion is set short in order to communicate the sealed space with the inside of the case when the inner member slides. However, the present invention is not limited to this. For example, a groove that communicates with the sealed space may be provided on the outer periphery on the tip side of the protrusion, and this groove may communicate with the inside of the case when the inner member slides.

1,2,3,4 ... Lithium ion secondary battery (battery)
10 ... storage element 15 ... positive electrode current collecting tab (positive electrode)
17 ... Negative electrode current collecting tab (negative electrode)
DESCRIPTION OF SYMBOLS 30 ... Case 35 ... Pressure valve 50, 60, 70, 80 ... Positive electrode terminal 51 ... Outer member 511 ... Cylindrical part 512 ... Gutter part 52, 62 ... Inner member 521, 621 ... Base part 522,622 ... Projection part 53 ... Engagement Stopper (connection holding means)
58, 68 ... sealed space 59 ... thermal expansion material (drive means)
71: Elastic member (driving means)
73 ... weld layer (connection holding means)
95, 98, 99 ... Positive current collecting lead plate (lead plate, connection holding means)
100: negative terminal

Claims (8)

A storage element comprising a positive electrode and a negative electrode;
A positive electrode terminal electrically connected to the positive electrode;
A negative electrode terminal electrically connected to the negative electrode;
A battery comprising a case for containing and holding the power storage element,
The terminal of at least one of the positive terminal and the negative terminal is
A cylindrical portion having one end closed and the other end opened, and a flange extending radially outward from the opening end, the closed end side being disposed outside the case, and the opening end side being the An outer member disposed inside the case and fixed to the case;
A base portion electrically connected to the one electrode, and a protrusion that protrudes from the base portion and is slidably fitted into the cylindrical portion, and the base portion abuts on the flange portion, An inner member electrically connected to the outer member;
In a normal state, a connection holding means for holding an electrical connection between the inner member and the outer member by holding the base portion in contact with the flange portion;
Drive means for generating a driving force for sliding the inner member in the axial direction of the cylindrical portion by heat, and
When the battery generates heat, due to the driving force generated by the driving means, the connection by the connection holding means is released, and the inner member slides in a direction in which the base part is separated from the collar part. A battery characterized in that an electrical connection between an inner member and the outer member is restricted or blocked. In a normal state, a sealed space is formed between the protruding portion and the cylindrical portion,
The connection holding means is a locking claw for locking the inner member to the outer member,
The drive means is a thermal expansion material that is enclosed in the sealed space and expands in volume by heat,
When the battery generates heat, the volume of the thermal expansion material expands, so that the locking by the locking claw is released, and the inner member slides in a direction in which the base part is separated from the collar part. The battery according to claim 1, wherein the electrical connection between the inner member and the outer member is limited or blocked.   3. The protrusion according to claim 2, wherein the protrusion is a hollow protrusion having an open end, or a protrusion having a protrusion length shorter than the length of the cylindrical portion. battery. The protrusion is formed so that the sealed space communicates with the inside of the case when the inner member slides in a direction in which the base is separated from the flange.
The thermal expansion material includes a fire extinguishing agent,
When the battery generates heat, the volume of the thermal expansion material expands, so that the connection by the connection holding means is released, and the inner member slides in a direction in which the base part is separated from the flange part. The electrical connection between the inner member and the outer member is restricted or blocked, and the fire extinguishing agent is introduced into the case through communication between the sealed space and the inside of the case. The battery according to claim 2 or 3.   The battery according to claim 4, wherein the case includes a pressure valve that releases the pressure in the case. The protruding portion is formed so that the protruding length is shorter than the length of the cylindrical portion,
The connection holding means is a weld layer for welding the inner member and the outer member;
The driving means is an elastic member made of a shape memory alloy that is disposed in a sealed space formed by the protrusion and the cylindrical portion and extends in the axial direction of the cylindrical portion by heat,
When the battery generates heat, the elastic member made of the shape memory alloy extends in the axial direction of the cylindrical portion, so that the weld layer is broken and the base portion is separated from the flange portion in the inner direction. The battery according to claim 1, wherein the sliding of the member restricts or blocks electrical connection between the inner member and the outer member. The protruding portion is formed so that the protruding length is shorter than the length of the cylindrical portion,
The connection holding means is a lead plate that electrically connects the base and the one electrode, and biases the inner member in a direction in which the base contacts the flange.
The driving means is an elastic member made of a shape memory alloy that is disposed in a sealed space formed by the protrusion and the cylindrical portion and extends in the axial direction of the cylindrical portion by heat,
When the battery generates heat, the elastic member made of the shape memory alloy extends in the axial direction of the cylindrical portion, so that the base portion is separated from the flange portion against the urging force of the lead plate. The battery according to claim 1, wherein the inner member slides to restrict or block electrical connection between the inner member and the outer member.   A battery module comprising the batteries according to claim 1 connected in parallel.

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