JP5699869B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery.

  In recent years, secondary batteries with small size and high output have been used for mobile phones and many home appliances. Moreover, in an electric vehicle or a hybrid vehicle, a battery module having a higher output and a larger capacity is used by connecting a plurality of secondary battery cells. In the secondary battery, an excessive current is concentrated due to a short circuit or the like, which may lead to a temperature rise of the secondary battery. Therefore, the secondary battery is provided with a mechanism that cuts off the current when an excessive current flows. For example, in Patent Document 1, a tin (Sn) alloy film is interposed between a negative electrode lead and a negative electrode terminal to be electrically connected. When an excessive current flows, the tin alloy film is melted and the junction between the negative electrode lead and the negative electrode terminal is released to interrupt the current.

  Further, in the nonaqueous electrolyte secondary battery of Patent Document 2, the normally closed fixed contact of the battery side terminal and the normally closed fixed contact of the load side terminal are connected by a contact plate. The contact plate is held by being pressed against the cup portion by an elastic body, and the cup portion is coupled to the screw rod by a low melting point heat-soluble metal. The screw rod is connected to a heat sensitive rod that conveys the temperature of the charged part in the battery. When the temperature in the battery rises, heat is transferred from the heat-sensitive rod to the screw rod and the heat-soluble metal, and when the heat-soluble metal melts, the coupling between the cup portion and the screw rod is released and the cup portion comes into contact with the elastic body. Push the board up. When the contact plate is pushed up, the normally closed side fixed setting of the battery side terminal and the normally closed side fixed contact of the load side terminal are cut off. Thereby, the battery and the load are protected safely.

JP 2009-211136 A JP 2000-182596 A

  However, the tin alloy film of Patent Document 1 has a problem that the resistance is higher than that of the negative electrode lead and the negative electrode terminal. Tin has a resistance 10 times higher than that of aluminum (Al) or copper (Cu) used for electrodes. Therefore, since the current flowing between the negative electrode lead and the negative electrode terminal passes through the tin alloy film, extra energy loss occurs. Moreover, in patent document 2, there exists a problem that a structure is complicated. In the non-aqueous electrolyte secondary battery of Patent Document 2, the temperature in the battery is transmitted to the heat-soluble metal through a screw rod with a heat sensitive rod, and the structure is complicated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a secondary battery with a simple structure and a low energy loss that can interrupt current.

In order to solve the above-described problems, the present invention provides a secondary battery having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and is connected to the positive electrode or the negative electrode so as to be freely energized. A first connection member that contacts the negative electrode; a connection portion that includes a second connection member that is in contact with the first connection member and one that can be connected to an external device; and the first connection member and the second connection member and a contact can be switched spaced switching members with the switching member comprises a shape memory alloy, when the switching member exceeds a predetermined temperature, separated from the first connecting member and the second connecting member The predetermined temperature is a temperature at the transformation point of the shape memory alloy, and the first connection member is provided with a first through hole at a portion that contacts the second connection member, and the second connection member Is provided with a second through hole at a position facing the first through hole, The switching member includes a main body portion inserted through the first through hole and the second through hole, and an opening / closing for contacting or separating the second connection member and the first connection member at both ends of the main body portion. Part is formed, and the opening and closing part opens and closes at a position on the outer peripheral side with respect to the first through hole and the second through hole, and when the temperature of the transformation point is exceeded, the main body part and the first through hole and The second through hole is locked .

In the present invention, the switching member holds the first connection member and the second connection member in a state in which the first connection member and the second connection member are in contact with each other so as to be energized. Further, when the switching member exceeds a predetermined temperature, the first connecting member and the second connecting member are switched to a separated state. Therefore, it is possible to provide a secondary battery that can cut off current with a simple structure and has low energy loss. Further, the predetermined temperature can be changed to a desired temperature depending on the type of the shape memory alloy, and the shape memory alloy can be reused any number of times. In addition, the shape memory alloy can be reliably locked and there is no need to provide a new member for holding the shape memory alloy. In the secondary battery of the present invention, the positive electrode and the negative electrode are preferably plate-shaped.

  According to the present invention, it is possible to provide a secondary battery with a simple structure and a low energy loss that can interrupt current.

It is a perspective view which shows the secondary battery which concerns on the reference example of this invention. It is sectional drawing which shows the secondary battery which concerns on the reference example of this invention. It is sectional drawing which shows the AA cross section of FIG. It is sectional drawing which shows the BB cross section of FIG. It is sectional drawing which shows the effect | action of the secondary battery in the AA cross section of FIG. It is a cross-sectional view of a rechargeable battery according to the implementation embodiments of the present invention. It is sectional drawing which shows the effect | action of the secondary battery shown in FIG. It is sectional drawing which shows the modification 1 of this invention. It is sectional drawing which shows the modification 2 of this invention. It is sectional drawing which shows the modification 3 of this invention. It is sectional drawing which shows the modification 4 of this invention. It is sectional drawing which shows the effect | action of the secondary battery shown in FIG. It is sectional drawing which shows the modification 5 of this invention.

( Reference example )
Hereinafter, the secondary battery according to the reference example will be described with reference to the drawings.
As shown in FIG. 1, the secondary battery 10 is a rectangular secondary battery having a rectangular case 11. The case 11 is a metal housing. The case 11 of this reference example is made of aluminum (Al). An electrolyte inlet 14 and a pressure valve 15 are provided on the upper surface of the case 11. The electrolyte solution inlet 14 can be freely opened and closed so that the electrolyte solution can be injected into the case 11. Further, the pressure valve 15 is broken when the pressure of the gas in the case 11 rises to a predetermined pressure or more, and exhausts the gas to the outside of the case 11.

On the upper surface of the case 11, a positive electrode terminal 16 and a negative electrode terminal 17 are provided at positions where the electrolyte solution inlet 14 and the pressure valve 15 are sandwiched. The positive electrode terminal 16 and the negative electrode terminal 17 are terminals that can be connected to an external device when charging / discharging. The positive electrode terminal 16 and the negative electrode terminal 17 are each formed in a rectangular thin plate shape. The positive terminal 16 is made of aluminum in this reference example . The negative electrode terminal 17 is formed using copper (Cu). The positive electrode terminal 16 and the negative electrode terminal 17 protrude upward from the inside of the case 11 so as to penetrate the case 11 as shown in the longitudinal sectional views of FIGS. 2, 3, and 4. The positive terminal 16 and the negative terminal 17 are fixedly supported in a state of being insulated from the case 11 via an insulating member (not shown). In addition, the positive electrode terminal 16 and the negative electrode terminal 17 of this reference example are equivalent to the 2nd connection member of invention.

A positive electrode tab connection plate 18 is connected to the lower end of the positive electrode terminal 16 so that the surfaces abut on each other. Further, a negative electrode tab connection plate 19 is connected to the lower end of the negative electrode terminal 17 so as to come into contact with each other. The positive electrode tab connection plate 18 and the negative electrode tab connection plate 19 are formed in a rectangular thin plate shape. The positive electrode tab connection plate 18 is made of aluminum. The negative electrode tab connection plate 19 is made of copper. The positive electrode tab connection plate 18 is disposed so as to extend horizontally from the lower end of the positive electrode terminal 16 toward the right side in FIG. Further, the negative electrode tab connection plate 19 is disposed so as to extend from the lower end of the negative electrode terminal 17 toward the left side. In this reference example , the positive electrode tab connection plate 18 and the negative electrode tab connection plate 19 correspond to the first connection member of the invention. Further, the positive electrode terminal 16, the negative electrode terminal 17, the positive electrode tab connection plate 18 and the negative electrode tab connection plate 19 constitute a connection portion of the present invention.

As shown in FIG. 3, a second through hole 16 </ b> A that penetrates in the thickness direction of the plate is formed at the lower end of the positive electrode terminal 16. The positive electrode tab connection plate 18 is formed with a first through hole 18A penetrating in the thickness direction of the plate at a position facing the second through hole 16A. In the reference example , the second through hole 16A and the first through hole 18A have the same diameter. The positive electrode terminal 16 and the positive electrode tab connection plate 18 are disposed at the contact positions so that the second through hole 16A and the first through hole 18A communicate with each other. Note that, in the negative electrode terminal 17 and the negative electrode tab connection plate 19 in the present reference example , the first through hole 17A and the second through hole 19A (see FIG. 4) are respectively formed in the same manner as the positive electrode terminal 16 and the positive electrode tab connection plate 18. Has been.

A low melting point alloy 20 is inserted into the second through hole 16A and the first through hole 18A as a switching member capable of switching between contact and separation between the positive electrode terminal 16 and the positive electrode tab connection plate 18. The low melting point alloy 20 energizes between the positive electrode terminal 16 and the positive electrode tab connection plate 18 by contacting the positive electrode terminal 16 and the positive electrode tab connection plate 18. The low melting point alloy 20 is also inserted into the first through hole 17A of the negative electrode terminal 17 and the second through hole 19A of the negative electrode tab connection plate 19. The low melting point alloy 20 is, for example, an alloy of tin (Sn) and indium (In). In addition, zinc (Zn) may be included. The low melting point alloy 20 is preferably an alloy having a melting point in the range of 80 to 120 degrees Celsius. In this reference example , an alloy having a melting point of 100 degrees Celsius is selected. The melting point of the low melting point alloy 20 is set to a value lower than the melting points of the positive electrode terminal 16, the negative electrode terminal 17, the positive electrode tab connection plate 18, and the negative electrode tab connection plate 19.

  The low melting point alloy 20 is a rivet having a hemispherical round head at one end. The low melting point alloy 20 is inserted into the second through hole 16A and the first through hole 18A, and then the other end is crushed to form a hemisphere. Similarly, the negative electrode terminal 17 and the negative electrode tab connection plate 19 are also held in a state where the surfaces are in contact with each other by a low melting point alloy which is a rivet having a hemispherical round head.

A positive electrode tab 25 is connected to the other end of the positive electrode tab connection plate 18 whose one end is connected to the positive electrode terminal 16. A negative electrode tab 26 is connected to the other end of the negative electrode tab connection plate 19 whose one end is connected to the negative electrode terminal 17. The positive electrode tab connection plate 18 and the negative electrode tab connection plate 19 connect the positive electrode tab 25 and the positive electrode terminal 16, and the negative electrode tab 26 and the negative electrode terminal 17 so as to be freely energized at the same height position. As shown in FIG. 3, the positive electrode tab 25 is connected to the positive electrode plate 31. As shown in FIG. 4, the negative electrode tab 26 is connected to the negative electrode plate 32. The positive electrode plate 31 and the negative electrode plate 32 are thin rectangular plates. The positive electrode plate 31 and the negative electrode plate 32 are superposed in a stacked state while being insulated via the separator 33. In this reference example , a positive electrode plate 31 and a negative electrode plate 32 are laminated with a separator 33 interposed therebetween to form a battery element 35. The battery element 35 is laminated in the order of the separator 33, the negative electrode plate 32, the separator 33, the positive electrode plate 31, and the separator 33 from the right in FIG. In this reference example , the positive electrode plate 31 corresponds to the positive electrode of the invention, and the negative electrode plate 32 corresponds to the negative electrode of the invention.

The battery element 35 is housed in the case 11 by folding the laminated positive electrode plate 31, negative electrode plate 32, and separator 33 in two. The battery element 35 in FIG. 2 has a U-shape that is bent downward in a convex state. A positive electrode tab 25 and a negative electrode tab 26 are formed on the U-shaped upper end portion of the positive electrode plate 31 and the negative electrode plate 32 so as to be connected to the positive electrode tab connection plate 18 and the negative electrode tab connection plate 19, respectively. In this reference example , two positive electrode tabs 25 are overlapped and connected to the positive electrode tab connection plate 18. Similarly, on the negative electrode side, two negative electrode tabs 26 are connected to the negative electrode tab connection plate 19. The battery element 35 is entirely covered with an insulating film (not shown) and accommodated in the case 11.

In the secondary battery 10 of the present reference example , the positive electrode tab connection plate 18 is connected to the battery element 35 via the positive electrode tab 25 so as to be freely energized. The negative electrode tab connection plate 19 is connected to the battery element 35 through the negative electrode tab 26 so as to be energized. The positive electrode terminal 16 connects the positive electrode tab connection plate 18 and an external device. The negative electrode terminal 17 connects the negative electrode tab connection plate 19 and an external device. Furthermore, in this reference example , the positive electrode plate 31 and the positive electrode tab 25 are made of aluminum, and a material having a melting point higher than that of the low melting point alloy 20 is selected. The negative electrode plate 32 and the negative electrode tab 26 are made of copper, and a material having a melting point higher than that of the low melting point alloy 20 is used.

Next, the effect | action about interruption | blocking of the electric current in the secondary battery 10 of this reference example is demonstrated.
When the secondary battery 10 is charged and discharged, a current flows between the positive electrode terminal 16 and the negative electrode terminal 17 and the battery element 35. A current is guided between the positive electrode terminal 16 and the positive electrode plate 31 via the positive electrode tab connection plate 18 and the positive electrode tab 25. Further, a current flows between the negative electrode terminal 17 and the negative electrode plate 32 via the negative electrode tab connection plate 19 and the negative electrode tab 26. Here, when an internal short circuit or overcharge occurs, the temperature rises in the case 11 of the secondary battery 10. When the temperature in the case 11 becomes higher than the melting point temperature of the low melting point alloy 20, the low melting point alloy 20 melts and flows.

  When the low melting point alloy 20 that has held the positive electrode terminal 16 and the positive electrode tab connection plate 18 in contact with each other melts and flows, the positive electrode terminal 16 and the positive electrode tab connection plate 18 are switched to a separated state. Then, a slight gap is generated between the positive terminal 16 and the positive tab connecting plate 18 as shown in FIG. The positive electrode terminal 16 and the positive electrode tab connection plate 18 are separated so as not to contact each other due to a gap, and the current flow is interrupted. Also, in the negative electrode terminal 17 and the negative electrode tab connection plate 19, when the low melting point alloy 20 is heated to the melting point temperature or higher, it melts and flows. Then, the negative electrode terminal 17 and the negative electrode tab connection plate 19 are separated from each other by a gap from the contact state, and the current flow is interrupted. At the positive electrode terminal 16 and the negative electrode terminal 17, the flow of current is interrupted, and charging / discharging is stopped even in the battery element 35 of the secondary battery 10. And the heat_generation | fever in the battery element 35 stops and it is gradually cooled by surrounding air.

According to this reference example , the following effects can be obtained.
(1) The low melting point alloy 20 can hold the positive electrode terminal 16 and the positive electrode tab connection plate 18 in contact with each other, and a current can flow without passing through the low melting point alloy 20. Further, the negative electrode terminal 17 and the negative electrode tab connection plate 19 can also be held in contact with each other and a current can flow.
(2) Since the low melting point alloy 20 melts and flows when the melting point temperature is exceeded, the positive electrode terminal 16 and the positive electrode tab connection plate are switched from the state in which the positive electrode terminal 16 and the positive electrode tab connection plate 18 are in contact with each other. A gap is generated between 18 and current flow can be interrupted. Moreover, the negative electrode terminal 17 and the negative electrode tab connection plate 19 can be switched from a contact state to a separated state, thereby interrupting the flow of current.

(3) Since the low melting point alloy 20 is an alloy having a melting point lower than that of the positive electrode plate 31, the negative electrode plate 32 and the separator 33, the current can be interrupted before the positive electrode plate 31, the negative electrode plate 32 and the separator 33 are melted. Thereby, it can prevent reliably that the positive electrode plate 31, the negative electrode plate 32, and the separator 33 are damaged by a temperature rise.
(4) The positive electrode terminal 16 and the positive electrode tab connection plate 18 are disposed so that the surfaces abut against each other. Further, the negative electrode terminal 17 and the negative electrode tab connection plate 19 are arranged so that the surfaces are in contact with each other. Therefore, no current flows through the low-melting-point alloy 20 having a large resistance, and the internal resistance of the electrode can be reduced and the loss can be suppressed. And the nonuniform reaction of an electrode can be prevented and a power density can be improved.

(5) The positive electrode tab connection plate 18 and the negative electrode tab connection plate 19 are disposed so as to extend in the lateral direction in the case 11. Since the positive electrode tab 25 and the negative electrode tab 26 and the positive electrode terminal 16 and the negative electrode terminal 17 are electrically connected at the same height position, dead space generated above the battery element 35 in the case 11 is minimized. The volume energy density of the secondary battery 10 can be improved.
(6) Since the low melting point alloy 20 is a rivet, the assembly of the positive electrode terminal 16 and the positive electrode tab connection plate 18 and the assembly of the negative electrode terminal 17 and the negative electrode tab connection plate 19 are easy.

(7) The low melting point alloy 20 holds the positive electrode terminal 16 and the negative electrode terminal 17 in contact with the positive electrode tab connection plate 18 and the negative electrode tab connection plate 19, respectively, and melts and flows when the melting point temperature is exceeded. Switch from the contacted state to the separated state. Therefore, the current can be interrupted when the temperature rises to the temperature at which the low melting point alloy 20 is melted on either the positive electrode terminal 16 or the negative electrode terminal 17 side.

(Implementation form)
For implementation of the invention Figure 6 is described below based on FIG.
Implementation embodiment is a modification of the low melting point alloy 20 as a metal member in reference example in the shape memory alloy 40. Except for the changes, the configuration is the same as that of the reference example , and the description is omitted. Furthermore, the same member as the reference example is described using the same member number.
As shown in FIG. 6, the shape memory alloy 40 communicates with the second through hole 16 </ b> A of the positive electrode terminal 16 and the first through hole 18 </ b> A of the positive electrode tab connection plate 18.

  The shape memory alloy 40 has a main body portion 40A inserted through the second through hole 16A and the first through hole 18A. The main body 40A is a cylindrical bar member. The diameter of the main body 40A is set slightly smaller than the diameters of the second through hole 16A and the first through hole 18A. At both ends of the main body portion 40A, an opening / closing portion 40B divided into upper and lower portions is provided. The opening / closing part 40B has an L-shaped hook shape. The opening / closing part 40B of the shape memory alloy 40 is opened up and down as shown in FIG. 6 at a temperature lower than a predetermined temperature. The opening / closing part 40B is set to contact the positive terminal 16 or the positive tab connecting plate 18 in a state where it is opened up and down. The opening / closing part 40B is in a state where the positive electrode terminal 16 and the positive electrode tab connection plate 18 are in contact with each other, and the positive electrode terminal 16 and the positive electrode tab connection plate 18 are in contact with each other.

  When the shape memory alloy 40 of this embodiment is heated to a predetermined temperature or higher, the shape changes as shown in FIG. The shape memory alloy 40 moves to a position where the opening / closing portion 40B extends linearly from the end of the main body portion 40A at a predetermined temperature or higher. At this time, the distal end of the L-shaped opening / closing part 40B is a position protruding to the outer peripheral side from the position of the diameter of the main body part 40A. Furthermore, the tip of the opening / closing part 40B protrudes to a position having a diameter larger than the diameters of the second through hole 16A of the positive electrode terminal 16 and the first through hole 18A of the positive electrode tab connection plate 18. That is, the opening / closing part 40B is a position where it is caught by the positive electrode terminal 16 and the positive electrode tab connection plate 18, and the main body part 40A does not fall out of the second through hole 16A and the first through hole 18A.

  In this embodiment, the transformation point of the shape memory alloy 40 is set to 100 degrees Celsius as the predetermined temperature. The temperature of the transformation point of the shape memory alloy 40 is set lower than the melting point temperature of the positive electrode terminal 16 and the positive electrode tab connection plate 18. Further, the transformation point temperature of the shape memory alloy 40 is lower than the temperatures of the positive electrode plate 31, the negative electrode plate 32, and the separator 33 in the battery element 35. In the present embodiment, the negative electrode terminal 17 and the negative electrode tab connection plate 19 are provided with a shape memory alloy 40 as a switching member, similarly to the positive electrode terminal 16 and the positive electrode tab connection plate 18. The shape is the same as that of the positive electrode terminal 16 shown in FIGS. 6 and 7, and the arrangement is symmetrical. Therefore, detailed description is omitted.

Next, an effect | action about interruption | blocking of the electric current in this embodiment is demonstrated.
When the secondary battery 10 is charged and discharged, current flows between the positive electrode terminal 16, the negative electrode terminal 17, and the battery element 35. A current is guided between the positive electrode terminal 16 and the positive electrode plate 31 via the positive electrode tab connection plate 18 and the positive electrode tab 25. Further, a current flows between the negative electrode terminal 17 and the negative electrode plate 32 via the negative electrode tab connection plate 19 and the negative electrode tab 26. Here, when an internal short circuit or overcharge occurs, the temperature rises in the case 11 of the secondary battery 10. And if temperature rises in the case 11 more than the predetermined temperature which is the temperature of the transformation point of the shape memory alloy 40, the shape memory alloy 40 will move so that the opening-and-closing part 40B may close.

  The positive electrode terminal 16 and the positive electrode tab connecting plate 18 are held so as to be in contact with the opening / closing portion 40B of the shape memory alloy 40 as shown in FIG. 6, but are in contact with the shape memory alloy 40 as shown in FIG. Switched to a separated state. Then, the positive electrode terminal 16 and the positive electrode tab connection plate 18 are separated from each other with a slight gap therebetween, thereby interrupting the current. When the opening / closing part 40B moves, the main body part 40A of the shape memory alloy 40 can move freely through the second through hole 16A of the positive electrode terminal 16 and the first through hole 18A of the positive electrode tab connection plate 18. However, the tip of the opening / closing part 40B is at a position larger in diameter than the diameters of the second through hole 16A and the first through hole 18A, and the shape memory alloy 40 is held without falling off from the positive terminal 16 and the positive tab connecting plate 18. The

When the opening / closing part 40B of the shape memory alloy 40 moves and the positive electrode terminal 16 and the positive electrode tab connection plate 18 are in a free state and the current is interrupted, the battery element 35, the positive electrode terminal 16, the positive electrode tab connection plate 18 and the like Will not flow and the temperature will not rise further. Then, as the secondary battery 10 radiates heat into the surrounding air, the temperature in the case 11 gradually decreases.
In addition, although the effect | action of the electric current interruption in the positive electrode terminal 16 and the positive electrode tab connection board 18 was demonstrated, since the electric current interruption in the negative electrode terminal 17 and the negative electrode tab connection board 19 is the same effect | action, description is abbreviate | omitted.

According to this embodiment, in addition to the effects (1), (4), and (5) of the reference example , the following effects can be obtained.
(8) When the shape memory alloy 40 is heated to a predetermined temperature that is the temperature of the transformation point, the opening / closing part 40B moves. Therefore, the current can be interrupted by switching from the state in which the positive electrode terminal 16 and the positive electrode tab connection plate 18 are in contact to the separated state. Similarly, the negative electrode terminal 17 and the negative electrode tab connection plate 19 can also be switched from the contacted state to the separated state, thereby interrupting the current.
(9) The temperature of the transformation point of the shape memory alloy 40 is lower than the melting points of the positive electrode terminal 16, the negative electrode terminal 17, the positive electrode tab connection plate 18, the negative electrode tab connection plate 19, the positive electrode plate 31, the negative electrode plate 32, and the separator 33. Is set to a value. Therefore, each terminal and the battery element 35 can be protected.

(10) In the shape memory alloy 40, the main body portion 40 </ b> A is inserted through the second through hole 16 </ b> A of the positive electrode terminal 16 and the first through hole 18 </ b> A of the positive electrode tab connection plate 18. Therefore, assembly is easy.
(11) Even when the opening / closing portion 40B of the shape memory alloy 40 is heated and moved to a temperature equal to or higher than the temperature of the transformation point, it exists at a position having a diameter larger than the diameters of the second through hole 16A and the first through hole 18A. The shape memory alloy 40 does not fall off from the positive electrode terminal 16 and the positive electrode tab connection plate 18. Therefore, the shape memory alloy 40 does not contact the battery element 35 to cause further short circuit.

(12) The shape memory alloy 40 can set the temperature of the transformation point, which is a predetermined temperature, by changing the type and ratio of the material of the alloy.
(13) The shape memory alloy 40 can be reused as a switching member after being heated to a temperature equal to or higher than the transformation point and moving to close the opening / closing part 40B if it is cooled to a temperature equal to or lower than the temperature of the transformation point.

The present invention is not limited to the above embodiment, and modifications of the present invention will be described below.
In the reference example , the shapes of the second through hole 16A and the first through hole 18A may be changed. For example, you may provide the inclination of a taper surface in a through-hole like the modification 1 shown in FIG. Moreover, you may provide the inclination of the reverse direction to FIG. 8 like the modification 2 shown in FIG. As shown in FIG. 9, when a tapered surface having a diameter increasing toward the surface where the second through-hole 16A and the first through-hole 18A are in contact is provided, It flows down between the surfaces where the terminals 16 and the positive electrode tab connection plate 18 abut, and the two members can be separated more reliably.
The low melting point alloy 20 may not be inserted into the through holes of the positive electrode terminal 16 and the positive electrode tab connection plate 18. For example, as in Modification 3 shown in FIG. 10, a shape having a C-shaped cross section surrounding the contact portion between the positive electrode terminal 16 and the positive electrode tab connection plate 18 may be used. Thereby, it is not necessary to provide a through-hole in the positive electrode terminal 16 and the positive electrode tab connection plate 18, and a processing man-hour can be reduced. That is, it is only necessary that the positive electrode terminal 16 and the positive electrode tab connection plate 18 can be held in direct contact with each other.

The shape memory alloy 40 may support the positive electrode terminal 16 and the positive electrode tab connection plate 18 so as to be actively separated. For example, as in Modification 4 shown in FIG. 11, a recess is provided in the contact portion between the positive electrode terminal 16 and the positive electrode tab connection plate 18. A protrusion 40C is provided on the main body 40A of the shape memory alloy 40. When the shape memory alloy 40 is heated to a temperature higher than the transformation point, as shown in FIG. 12, the protrusion 40C is bifurcated, and the positive electrode terminal 16 and the positive electrode tab connection plate 18 are separated from each other. As described above, a gap may be positively formed between the positive electrode terminal 16 and the positive electrode tab connection plate 18. Note that the negative electrode side may have the same configuration.
The battery element 35 is not limited to the configuration of the embodiment. For example, a winding battery element 35 may be used as in Modification 5 shown in FIG. In this case, the positive electrode tab 25 and the negative electrode tab 26 may be protruded laterally in the case 11 and the positive electrode tab connection plate 18 and the negative electrode tab connection plate 19 may be provided in the vertical direction. Further, the battery element 35 may be a stacked type in which separate positive electrode plates 31, negative electrode plates 32, and separators 33 are stacked several times. The number of times of lamination is not limited, with a winding type and a lamination type.

In the embodiment, the low melting point alloy 20 and the shape memory alloy 40 are provided on the positive electrode side and the negative electrode side as switching members, respectively, but may be provided only on either the positive electrode side or the negative electrode side.
A spring or the like may be provided between the positive electrode terminal 16 and the positive electrode tab connection plate 18. When the low melting point alloy 20 or the shape memory alloy 40 as the switching member releases the positive electrode terminal 16 and the positive electrode tab connection plate 18 to a free state at a predetermined temperature or higher, the positive electrode terminal 16 and the positive electrode tab connection plate 18 are positively activated by a spring or the like. If a gap is formed between the two, the current can be interrupted more reliably.

○ As the low melting point alloy 20, an alloy having a melting point of 80 degrees Celsius to 120 degrees Celsius is selected, but other alloys may be used. If the material of the positive electrode terminal 16, the positive electrode tab connection plate 18, the positive electrode plate 31, the negative electrode plate 32, and the separator 33 changes, it is necessary to change the melting point of the low melting point alloy 20. It is good to set so that it may become a value lower than melting | fusing point of the plate 31, the negative electrode plate 32, and the separator 33.
A plate-like member is used for the positive electrode terminal 16, the negative electrode terminal 17, the positive electrode tab connection plate 18, and the negative electrode tab connection plate 19, but shapes other than the plate may be used.

Closing portion 40B of ○ shape memory alloy 40 in the implementation form, when heated above a predetermined temperature, it may be configured to the main body portion 40A of the shape memory alloy 40 from falling out from the second through-hole 16A and the first through hole 18A . In that case, it is preferable that the shape memory alloy 40 is connected to the case 11 or the like and locked so as to be hooked.
O The switching member comprised by the low melting-point alloy 20 and the shape memory alloy 40 in embodiment is not limited to a metal. For example, the switching member may be formed of a thermoplastic resin.
The positive electrode tab connection plate 18 and the negative electrode tab connection plate 19 in the embodiment may be omitted. In that case, you may connect the positive electrode tab 25 as a 1st connection member, and the positive electrode terminal 16 as a 2nd connection member with the low melting-point alloy 20 etc. which are switching members. Moreover, you may connect the negative electrode tab 26 as a 1st connection member, and the negative electrode terminal 17 as a 2nd connection member with the low melting-point alloy 20 as a switching member.

DESCRIPTION OF SYMBOLS 10 Secondary battery 11 Case 14 Electrolyte injection port 15 Pressure valve 16 Positive electrode terminal 16A Second through-hole 17 Negative electrode terminal 18 Positive electrode tab connection plate 18A First through-hole 19 Negative electrode tab connection plate 20 Low melting point alloy 25 Positive electrode tab 26 Negative electrode tab 31 Positive electrode plate 32 Negative electrode plate 33 Separator 35 Battery element 40 Shape memory alloy 40A Main body portion 40B Opening and closing portion 40C Protruding portion

Claims (3)

In a secondary battery having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
A first connection member that is connected to the positive electrode or the negative electrode so as to be freely energized, abuts against the positive electrode or the negative electrode, and a second connection in which one abuts the first connection member and the other can be connected to an external device. A connecting portion having a member;
A switching member capable of switching contact and separation between the first connection member and the second connection member;
The switching member is made of a shape memory alloy, and when the switching member exceeds a predetermined temperature, the first connection member and the second connection member are separated ,
The predetermined temperature is a temperature of the transformation point of the shape memory alloy,
The first connecting member is provided with a first through hole in a portion that contacts the second connecting member,
The second connecting member is provided with a second through hole at a position facing the first through hole,
The switching member is configured to contact or separate the main body portion inserted through the first through hole and the second through hole, and the second connection member and the first connection member at both ends of the main body portion. An opening / closing part is formed,
The opening / closing part opens and closes at a position on the outer peripheral side of the first through hole and the second through hole, and when the temperature of the transformation point is exceeded, the main body part becomes the first through hole and the second through hole. A secondary battery that is locked in a hole . The switching member is locked to the second connection member while separating the first connection member and the second connection member when the temperature of the transformation point is exceeded. Secondary battery described in 1. The secondary battery according to claim 1 , wherein the positive electrode and the negative electrode have a plate shape .

Images