JP6810885B2 - Rechargeable battery - Google Patents

Description

The present invention relates to a secondary battery.

Secondary batteries such as lithium-ion secondary batteries (lithium secondary batteries) are lighter and have a higher energy density than existing batteries. Therefore, in recent years, they have been used as so-called portable power sources for personal computers and mobile terminals and power sources for driving vehicles. It is used. In particular, lithium-ion secondary batteries, which are lightweight and have high energy density, will become more and more popular as high-output power sources for driving vehicles such as electric vehicles (EV), hybrid vehicles (HV), and plug-in hybrid vehicles (PHV). It is expected to continue.

Secondary batteries, especially lithium-ion secondary batteries, are required to have high safety, especially when overcharged. Lithium-ion secondary batteries are generally sealed batteries, and if for some reason a current exceeding a specified value flows during charging and the battery becomes overcharged, the battery voltage rises, and the internal pressure of the battery rises and the battery temperature rises. Occur. Therefore, in lithium-ion secondary batteries, various safety measures are taken against overcharging, and one of the safety measures is a pressure type safety mechanism.

As a secondary battery provided with a pressure type safety mechanism, for example, in Patent Document 1, a cap assembly including an electrode assembly, a case for accommodating the electrode assembly, and a lid plate for sealing the case and having a short-circuit hole. A first short-circuit plate provided in the short-circuit hole, a second short-circuit plate provided so as to cover the short-circuit hole on the outside separated from the lid plate, and between the first short-circuit plate and the second short-circuit plate. A secondary battery including a short-circuit member including a third short-circuit plate is disclosed. The first short-circuit plate typically comprises an inversion plate that includes a downwardly projecting round portion and an edge portion that is fixed to the lid plate and formed on the edge of the round portion. In the secondary battery disclosed in Patent Document 1, when overcharging occurs and the internal pressure becomes larger than the set pressure, the round portion protruding downward of the first short-circuit plate is inverted and protrudes upward. When the round portion of the first short-circuit plate is inverted and protrudes, the second short-circuit plate is pushed up and comes into contact with the third short-circuit plate, and a short circuit is induced. When a short circuit occurs, the secondary battery is safely discharged.

Japanese Unexamined Patent Publication No. 2011-154992

However, as described in Patent Document 1, when an inversion plate is used, the thickness of the inversion plate needs to be reduced in order to have a structure flexible enough to be inverted by an increase in internal pressure. Therefore, when heat is generated by the current at the time of short circuit, the reversing plate may be melted.

Therefore, an object of the present invention is to provide a secondary battery provided with a pressure-type safety mechanism capable of causing a short circuit due to an increase in internal pressure during overcharging, and a pressure-type safety mechanism in which members are less likely to be blown during a short circuit.

The secondary battery disclosed herein includes a battery case, positive electrode terminals and negative electrode terminals provided on one surface of the battery case, and a short-circuit member. The positive electrode terminal has a positive electrode terminal protruding portion protruding toward the negative electrode terminal, and the negative electrode terminal has a negative electrode terminal protruding portion protruding toward the positive electrode terminal. A hole that communicates with the inside of the battery case is provided between the positive electrode terminal and the negative electrode terminal on one surface of the battery case. The short-circuit member has a sliding portion and a short-circuit plate portion. The sliding portion is arranged in the hole portion and slides from the inside direction to the outside direction of the battery case when the internal pressure of the battery case rises. The short-circuit plate portion has a length that allows contact with the positive electrode terminal protruding portion and the negative electrode terminal protruding portion. The short-circuit plate portion is arranged so that the positive electrode terminal protruding portion and the negative electrode terminal protruding portion can be electrically connected when the sliding portion slides from the internal direction to the external direction of the battery case. Has been done. The short-circuit plate portion has higher fusing resistance than at least one of the positive electrode terminal protruding portion and the negative electrode terminal protruding portion.

According to such a configuration, since the short-circuit member serving as the pressure-type safety mechanism causes a short-circuit due to sliding due to an increase in the internal pressure, the degree of freedom in designing the short-circuit plate portion of the short-circuit member is high. As a result, the short-circuit member can be provided with a short-circuit plate portion having high fusing resistance. Therefore, it is possible to provide a secondary battery provided with a pressure-type safety mechanism that can cause a short circuit due to an increase in internal pressure during overcharging, and a pressure-type safety mechanism in which members are less likely to be blown during a short circuit.

FIG. 1A is a top view schematically showing a configuration of a secondary battery according to a first embodiment of the present invention, and FIG. 1B is a cross section taken along line XX of FIG. 1A. 1 (c) is an enlarged view schematically showing the central portion of the round frame Y of FIG. 1 (b). It is sectional drawing which shows typically the state which the internal pressure of the secondary battery which concerns on 1st Embodiment of this invention increased. It is sectional drawing which shows typically the structure of the secondary battery which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the secondary battery which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows typically the structure of the secondary battery which concerns on 4th Embodiment of this invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in the present specification and necessary for carrying out the present invention (for example, general configurations and manufacturing processes of secondary batteries that do not characterize the present invention) are said to be relevant. It can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art. Further, in the following drawings, members / parts having the same action are described with the same reference numerals. In addition, the dimensional relationships (eg, length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships.

In the present specification, the "secondary battery" generally refers to a power storage device capable of repeatedly charging and discharging, and is a term including a so-called storage battery and a power storage element such as an electric double layer capacitor.

[First Embodiment]
FIG. 1 is a diagram schematically showing the configuration of the secondary battery 100A according to the first embodiment. 1 (a) is a top view of the secondary battery 100A in a normal use state, FIG. 1 (b) is a sectional view taken along line XX of FIG. 1 (a), and FIG. 1 (c) is FIG. 1 (c). It is an enlarged view which shows typically the central part of the round frame Y of b). The secondary battery 100A is, for example, a lithium ion secondary battery.

As shown in FIG. 1, the secondary battery 100A includes a battery case 10 and a positive electrode terminal 32 and a negative electrode terminal 42 on the upper surface as one surface of the battery case 10. On the upper surface of the battery case 10, a hole 12 communicating with the inside of the battery case 10 is provided between the positive electrode terminal 32 and the negative electrode terminal 42. Here, the hole portion 12 is circular. As the battery case 10, a flat and square battery case is used here. The battery case 10 is made of a lightweight metal having good thermal conductivity, such as aluminum.
The secondary battery 100A includes a non-aqueous electrolytic solution (not shown) in the battery case 10. The non-aqueous electrolyte solution may have the same configuration as that of a conventional secondary battery (eg, a lithium ion secondary battery). For example, the non-aqueous electrolytic solution may contain a carbonate-based solvent or the like as the non-aqueous solvent and a lithium salt such as LiPF ₆ as the supporting salt.
The secondary battery 100A includes an electrode body 20 housed inside the battery case 10.

In the electrode body 20, the positive electrode 30 and the negative electrode 40 are laminated. The positive electrode 30 and the negative electrode 40 are insulated via a separator (not shown). The electrode body 20 may be a laminated electrode body in which a plurality of positive electrode sheets, a plurality of negative electrode sheets, and a plurality of separators are laminated, and one positive electrode sheet, one negative electrode sheet, and two separators. May be a wound electrode body in which is laminated and wound.
The positive electrode 30 may have the same configuration as that of a conventional secondary battery (eg, a lithium ion secondary battery). For example, the positive electrode 30 may have a configuration in which a positive electrode active material layer containing a lithium transition metal composite oxide or the like as a positive electrode active material is provided on a positive electrode current collector such as an aluminum foil.
The negative electrode 40 may have the same configuration as that of a conventional secondary battery (eg, a lithium ion secondary battery). For example, the negative electrode 40 may have a configuration in which a negative electrode active material layer containing graphite or the like as a negative electrode active material is provided on a negative electrode current collector such as a copper foil.
The separator may have the same configuration as that of a conventional secondary battery (eg, a lithium ion secondary battery). For example, the separator may be a porous polyolefin resin sheet.

In the electrode body 20, a current collecting portion of the positive electrode 30 is provided at one end in the horizontal direction (the left end of FIG. 1B), and the current collecting portion of the positive electrode 30 passes through the positive electrode current collecting terminal 34. Is electrically connected to the positive electrode terminal 32. Similarly, in the electrode body 20, a current collecting portion of the negative electrode 40 is provided at the other end (right end of FIG. 1B) in the horizontal direction, and the current collecting portion of the negative electrode 40 is a negative electrode current collecting terminal. It is electrically connected to the negative electrode terminal 42 via 44.

A positive electrode insulating material 63 is arranged between the positive electrode terminal 32 and the battery case 10, and the positive electrode insulating material 63 insulates the positive electrode terminal 32 and the battery case 10. A negative electrode insulating material 64 is arranged between the negative electrode terminal 42 and the battery case 10, and the negative electrode insulating material 64 insulates the negative electrode terminal 42 and the battery case 10.
The positive electrode terminal 32 has a positive electrode terminal protruding portion 32a protruding toward the negative electrode terminal 42. Similarly, the negative electrode terminal 42 has a negative electrode terminal projecting portion 42a protruding toward the positive electrode terminal 32.

The secondary battery 100A includes a short-circuit member 50A. The short-circuit member 50A includes a sliding member 52A that serves as a sliding portion and a short-circuit plate 54A that serves as a short-circuit plate portion. The sliding member 52A has a cylindrical shape.
The sliding member 52A is arranged in the hole portion 12 by being inserted into the hole portion 12 provided on the upper surface of the battery case 10. A sealing material 56A is attached to the hole 12 so that the secondary battery 100A is completely sealed. Further, the sliding member 54A has a groove having a shape that matches the shape of the sealing material 56A, and the sealing material 56A is fitted into the groove. The sealing material 56A is for surely filling the gap between the sliding member 52A and the hole 12, and facilitates sliding when the internal pressure of the battery case 10 rises above a predetermined pressure. It is a purpose. In particular, by selecting the material, dimensions, etc. of the sealing material 56A, it is possible to easily adjust the internal pressure at which sliding is started.
The sealing material 56A may be attached to the sliding member 52A. Further, when the secondary battery 100A is completely sealed by the sliding member 52A, the sealing material 56A may not be used.
A holding member 80 for holding the short-circuit member 50A at a predetermined height is provided around the hole 12 inside the battery case 10 of the secondary battery 100A. During normal use of the secondary battery 100A, the sliding member 52A of the short-circuit member 50A is held in contact with the holding member.
When the internal pressure of the battery case 10 rises, the sliding member 52A slides from the inside direction to the outside direction of the battery case 10. That is, in FIG. 1B, the sliding member 52A slides upward.

The short-circuit plate 54A has a length that allows contact with the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a. Further, the dimensions of the upper surface of the short-circuit plate 54A in the short side direction (that is, the width direction) are the same as or larger than the dimensions of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a in the same direction. However, this dimension of the short-circuit plate 54A does not necessarily mean that the positive electrode terminal protrusion 32a and the negative electrode terminal in the same direction are required if the fusing resistance of the short-circuit plate 54A is higher than at least one of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a. It does not have to be equal to or larger than the size of the protrusion 42a.
The short circuit plate 54A is made of a conductive material.
The short-circuit plate 54A has higher fusing resistance than at least one of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a. In other words, when a current is passed at a predetermined high current value, the short-circuit plate 54A is blown later than at least one of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a.
In the first embodiment, as shown in FIG. 1B, the short-circuit plate 54A has dimensions in the direction perpendicular to the upper surface of the battery case 10 of the positive electrode terminal protrusion 32a and the battery case 10 of the negative electrode terminal protrusion 42a. It has a thickness larger than the dimension in the direction perpendicular to the upper surface. In FIG. 1B, the dimension of the positive electrode terminal protrusion 32a in the direction perpendicular to the upper surface of the battery case 10 is the thickness of the positive electrode terminal protrusion 32a and perpendicular to the upper surface of the battery case 10 of the negative electrode terminal protrusion 42a. The dimension in the above direction is the thickness of the negative electrode terminal protrusion 42a.
By increasing the thickness of the short-circuit plate 54A in this way, the short-circuit plate 54A has higher fusing resistance than the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a. It is also possible to design the dimensions so that the fusing resistance of the short-circuit plate 54A is higher than that of only one of the positive electrode terminal protrusion 32a or the negative electrode terminal protrusion 42a.
The method of increasing the fusing resistance of the short-circuit plate 54A to be higher than at least one of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a is not limited to the above. For example, the short-circuit plate 54A is made of a conductive material having a lower electrical resistance than at least one of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a, and the short-circuit plate 54A is made to have a fusing resistance of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion. It may be higher than at least one of the portions 42a. Further, for example, the short-circuit plate 54A is made of a conductive material having a melting point higher than at least one of the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a to improve the fusing resistance of the short-circuit plate 54A between the positive electrode terminal protrusion 32a and the negative electrode. It may be higher than at least one of the terminal protrusions 42a.

On the upper surface of the battery case 10, positive electrode hard walls 73 are provided on both sides of the positive electrode terminal 32, and negative electrode hard walls 74 are provided on both sides of the negative electrode terminal 42. The positive electrode hard wall 73 and the negative electrode hard wall 74 prevent the short-circuit plate 54A from rotating, thereby adjusting the position of the short-circuit plate 54A. Further, when the internal pressure of the battery case 10 rises and the sliding member 52A slides from the internal direction to the external direction of the battery case 10, the short-circuit plate 54A has the positive electrode terminal protruding portion 32a and the negative electrode terminal protruding portion. It is arranged so that it can be electrically connected to 42a. Such an arrangement is realized by appropriately setting the outer shape, size and position of the positive electrode terminal 32, the outer shape, size and position of the negative electrode terminal 42, and the size and position of the short-circuit member 50A.

FIG. 2 is a cross-sectional view schematically showing a state in which the internal pressure of the secondary battery 100A is abnormally increased due to, for example, overcharging. Due to the increase in the internal pressure of the battery case 10 of the secondary battery 100A, the sliding member 52A of the short-circuit member 50A slides upward, and the short-circuit plate 54A is in contact with the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a. .. Therefore, the positive electrode terminal protruding portion 32a and the negative electrode terminal protruding portion 42a are electrically connected. As a result, the current path shown by the arrow in FIG. 2 is formed, causing a short circuit.

In this way, when the internal pressure of the secondary battery 100A rises, a short circuit can be caused by the action of the short circuit member 50A, and the short circuit member 50A functions as a pressure type safety mechanism. Here, in the prior art, there is a problem that the reversing plate may be melted when heat is generated by the current at the time of short circuit due to the small thickness of the reversing plate serving as the short-circuit plate. However, since the short-circuit member 50A, which is the pressure-type safety mechanism of the secondary battery 100A, causes a short circuit due to sliding due to an increase in the internal pressure, the design of the short-circuit plate 54A, which is the short-circuit plate portion of the short-circuit member 50A, is free. The degree is high. As a result, the short-circuit member 50A can be provided with a short-circuit plate portion having high fusing resistance.
As described above, the secondary battery 100A is a pressure-type safety mechanism capable of causing a short circuit due to an increase in internal pressure during overcharging, and is configured as a secondary battery provided with a pressure-type safety mechanism in which members are unlikely to be blown during a short circuit. Has been done.

Hereinafter, another embodiment obtained by modifying the first embodiment will be described. In another embodiment described below, only the short-circuit member is different from the first embodiment, and therefore description other than the short-circuit member will be omitted.

[Second Embodiment]
FIG. 3 schematically shows the configuration of the secondary battery 100B of the second embodiment. The secondary battery 100B includes a short-circuit member 50B, and the short-circuit member 50B includes a sliding member 52B as a sliding portion and a short-circuit plate 54B as a short-circuit plate portion. The secondary battery 100B includes a sealing material 56B. Alternatively, the sliding member 52B includes a sealing material 56B. The sliding member 52B has a spherical shape, which is different from that of the first embodiment.
Similar to the cylindrical sliding member 52A of the first embodiment, the spherical sliding member 52B of the second embodiment slides in the hole portion in response to the increased pressure of the battery case 10. Can rise. As a result, the short-circuit plate 54B can electrically connect the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a, and the short-circuit member 50B can function as a pressure-type safety mechanism.
As described above, the shape of the sliding member of the short-circuit member is such that the short-circuit member is under pressure as long as the sliding member can slide and rise in the hole in response to the increased pressure in the battery case. Since it can function as a mold safety mechanism, it is not particularly limited.
As described above, the secondary battery 100B is a pressure-type safety mechanism capable of causing a short circuit due to an increase in internal pressure during overcharging, and is configured as a secondary battery provided with a pressure-type safety mechanism in which members are unlikely to be blown during a short circuit. Has been done.

[Third Embodiment]
FIG. 4 schematically shows the configuration of the secondary battery 100C of the third embodiment. The secondary battery 100C includes a short-circuit member 50C. The short-circuit member 50C is configured as a single component, and has a sliding portion 52C and a short-circuit plate portion 54C. The secondary battery 100C includes a sealing material 56C. Alternatively, the sliding portion 52C includes a sealing material 56C. The short-circuit member 50C of the third embodiment is different from the first embodiment in that the sliding member and the short-circuit plate are integrally formed as a single component.
Even in such a configuration, the short-circuit member 50C slides up in the hole portion in response to the increased pressure of the battery case 10, and the short-circuit plate portion 54C connects the positive electrode terminal protrusion 32a and the negative electrode terminal protrusion 42a. It can be electrically connected. Therefore, the short-circuit member 50C can function as a pressure-type safety mechanism.
As described above, in the short-circuit member, the sliding portion and the short-circuit plate portion do not have to be made of separate members.
As described above, the secondary battery 100C is a pressure-type safety mechanism capable of causing a short circuit due to an increase in internal pressure during overcharging, and is configured as a secondary battery provided with a pressure-type safety mechanism in which members are unlikely to be blown during a short circuit. Has been done.
The secondary battery is used as a power source for driving a vehicle. When a secondary battery is used as a power source for driving a vehicle, the secondary battery moves up and down due to the vibration of the vehicle. When the secondary battery moves up and down due to the vibration of the vehicle, the short-circuit plate portion of the short-circuit member tends to vibrate. If the vibration of the short-circuit plate portion is very large, the short-circuit plate portion may come into contact with the positive electrode terminal protrusion and the negative electrode terminal protrusion, and the pressure type safety mechanism may malfunction.
However, in the third embodiment, the short-circuit member 50C is configured as a single component, so that the vibration of the short-circuit plate portion 54C of the short-circuit member 50C when the secondary battery 100C moves up and down is suppressed. Therefore, in the third embodiment, there is an advantage that the pressure type safety mechanism is less likely to malfunction.

[Fourth Embodiment]
FIG. 5 schematically shows the configuration of the secondary battery 100D of the fourth embodiment. The secondary battery 100D includes a short-circuit member 50D, and the short-circuit member 50D includes a sliding member 52D as a sliding portion, a support member 58D, and two short-circuit plates 54D as short-circuit plate portions. The secondary battery 100D includes a sealing material 56D. Alternatively, the sliding member 52D includes a sealing material 56D. The support member 58D is attached to the sliding member 52D, and two short-circuit plates 54D are separately installed on the support member 58D. The two short-circuit plates 54D are electrically connected by a support member 58D. The support member 58D and the short-circuit plate 54D have higher fusing resistance than either the positive electrode terminal protrusion 32a or the negative electrode terminal protrusion 42a.
Even in such a configuration, the sliding member 52D slides up in the hole portion in response to the increased pressure of the battery case 10, and the two short-circuit plates 54D have the positive electrode terminal protruding portion 32a and the negative electrode terminal protruding portion. It can be electrically connected to 42a. Therefore, the short-circuit member 50D can function as a pressure-type safety mechanism.
As described above, the short-circuit member may include a short-circuit plate and a member other than the short-circuit plate.
As described above, the secondary battery 100D is a pressure-type safety mechanism capable of causing a short circuit due to an increase in internal pressure during overcharging, and is configured as a secondary battery provided with a pressure-type safety mechanism in which members are unlikely to be blown during a short circuit. Has been done.
The secondary battery is used as a power source for driving a vehicle. When a secondary battery is used as a power source for driving a vehicle, the secondary battery moves up and down due to the vibration of the vehicle. When the secondary battery moves up and down due to the vibration of the vehicle, the short-circuit plate of the short-circuit member tends to vibrate. If the vibration of the short-circuit plate is very large, the short-circuit plate may come into contact with the positive electrode terminal protrusion and the negative electrode terminal protrusion, and the pressure type safety mechanism may malfunction.
However, in the fourth embodiment, by dividing the short-circuit plate into two short-circuit plates 54D, vibration of the short-circuit plate 54D of the short-circuit member 50D when the secondary battery 100D moves up and down is suppressed. There is. Therefore, in the fourth embodiment, there is an advantage that the pressure type safety mechanism is less likely to malfunction.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

10 Battery case 12 Hole 20 Electrode body 30 Positive electrode 32 Positive electrode terminal 32a Positive electrode terminal protruding part 34 Positive current collecting terminal 40 Negative electrode 42 Negative electrode terminal 42a Negative electrode terminal protruding part 44 Negative electrode current collecting terminal 50A, 50B, 50C, 50D Short circuit member 52A, 52B, 52D Sliding member 52C Sliding part 54A, 54B, 54D Short-circuit plate 54C Short-circuit plate part 56A, 56B, 56C, 56D Sealing material 58D Support member 63 Positive electrode insulating material 64 Negative electrode insulating material 73 Positive electrode hard wall 74 Negative electrode hard wall 80 Holding member 100A, 100B, 100C, 100D secondary battery

Claims (4)

Battery case and
A positive electrode terminal and a negative electrode terminal provided on one surface of the battery case,
Short-circuit member and
It is a secondary battery equipped with
The positive electrode terminal has a positive electrode terminal projecting portion protruding toward the negative electrode terminal.
The negative electrode terminal has a negative electrode terminal projecting portion protruding toward the positive electrode terminal.
A positive electrode insulating material is arranged between the positive electrode terminal and the battery case, and the positive electrode insulating material insulates the positive electrode terminal and the battery case.
A negative electrode insulating material is arranged between the negative electrode terminal and the battery case, and the negative electrode insulating material insulates the negative electrode terminal and the battery case.
A hole communicating with the inside of the battery case is provided between the positive electrode terminal and the negative electrode terminal on one surface of the battery case.
The short-circuit member has a sliding portion and a short-circuit plate portion.
The sliding portion is arranged in the hole portion and slides from the inside direction to the outside direction of the battery case when the internal pressure of the battery case rises.
The short-circuit plate portion has a length that allows contact with the positive electrode terminal protrusion and the negative electrode terminal protrusion.
The short-circuit plate portion is arranged so that the positive electrode terminal protruding portion and the negative electrode terminal protruding portion can be electrically connected when the sliding portion slides from the internal direction to the external direction of the battery case. Has been
The short plate portion, said at least one fusing resistance than the positive terminal protrusion of the negative electrode terminal protrusions rather high,
When the internal pressure of the battery case rises, the short-circuit plate portion comes into contact with the positive electrode terminal protrusion and the negative electrode terminal protrusion, and the positive electrode terminal protrusion and the negative electrode terminal protrusion are electrically connected. Be done,
A secondary battery characterized by that. The width direction, which is the short-side dimension of the upper surface of the short-circuit plate portion, is the same as or larger than the dimensions of the positive electrode terminal protrusion and the negative electrode terminal protrusion in the same direction.
The thickness, which is the dimension in the direction perpendicular to the upper surface of the short-circuit plate portion, is the dimension in the direction perpendicular to the upper surface of the battery case of the positive electrode terminal protrusion and the direction perpendicular to the upper surface of the battery case of the negative electrode terminal protrusion. The secondary battery according to claim 1, which is larger than the size. The secondary battery according to claim 1, wherein the short-circuit plate portion is made of a conductive material having a lower electrical resistance than at least one of the positive electrode terminal protruding portion and the negative electrode terminal protruding portion. The secondary battery according to claim 1, wherein the short-circuit plate portion is made of a conductive material having a melting point higher than at least one of the positive electrode terminal protruding portion and the negative electrode terminal protruding portion.

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