JP2009076270A - Battery and power source system using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make self discharge started in the case of temperature rise, and thereby return a battery to a safe state. <P>SOLUTION: The battery is provided with a vessel (1, 1A), a cathode terminal (3) fitted to a lid part (1a) of the vessel (1, 1A), an anode terminal (2) fitted to the lid part (1a), and connection mechanisms (6 to 9) electrically connecting the cathode terminal (3) and the anode terminal (2). The connection mechanisms (6 to 9) are so structured that the cathode terminal (3) and the anode terminal (2) are electrically connected when specific members (6, 8) melt down due to temperature rise of the battery. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a battery, and more particularly to a technique for improving the safety of a battery that may cause thermal runaway, such as a lithium ion secondary battery.

  Lithium ion secondary batteries are characterized by high energy density, high output voltage, and long life compared to lead batteries, nickel metal hydride batteries and other secondary batteries. For this reason, small lithium ion secondary batteries have already been used commercially as power sources for electronic devices, and will be used in power storage systems such as power storage devices, electric vehicle power sources, and natural energy hybrid systems in the future. In order to apply this technology, research and development for putting large-sized lithium ion secondary batteries into practical use is underway.

  One of the important things in the operation of lithium ion secondary batteries is to ensure safety. If the operation of the lithium ion secondary battery is mistaken (for example, when overcharged), the crystal structure of the positive electrode material changes and heat is generated. It will lead to a thermal runaway that goes on. Lithium ion secondary batteries need to be secured to prevent thermal runaway. Lithium ion secondary batteries often use multiple potentials as assembled batteries, but in the case of assembled batteries connected in series, when the capacity of the battery varies due to some factor during use, the battery with a small capacity May be overcharged. Since this affects safety, control is performed so that overcharge and overdischarge do not occur in the control circuit. However, even when the control circuit does not operate normally due to a failure or the like, it is desirable that the battery itself has a mechanism for overcharging so that the safety of the battery can be ensured.

  One approach for ensuring battery safety is to place the lithium ion secondary battery in a safe state with a physical protection mechanism such as a safety valve before thermal runaway occurs. In general lithium ion secondary batteries, when the temperature rises, the safety valve operates at a temperature slightly lower than the temperature that leads to thermal runaway (for example, at 80 ° C. to 90 ° C.) to release the internal gas. , Configured to ensure safety. JP-A-7-192653 and JP-A-2004-259613 disclose that a material that melts at a temperature at which thermal runaway occurs and absorbs ambient heat as heat of fusion is provided inside the battery container, or A technique for securing safety by joining to the outside of a container is disclosed.

When exposed to an increase in temperature, it is desirable that the lithium ion secondary battery be returned to a safe state as much as possible. However, while the conventional protection mechanism effectively avoids thermal runaway, there is a problem that high voltage can be maintained between the positive electrode terminal and the negative electrode terminal because self-discharge does not proceed even if it operates. When a situation occurs in which the temperature of the lithium ion secondary battery rises excessively, maintenance work such as inspection and replacement needs to be performed. However, it is not preferable in terms of work safety to perform the maintenance work in a state where a high voltage is maintained between the positive terminal and the negative terminal.
Japanese Patent Application Laid-Open No. 7-192753 JP 2004-259613 A

  Therefore, an object of the present invention is to provide a technique for starting self-discharge when the temperature rises, thereby returning the battery to a safer state.

  In order to achieve the above object, the present invention employs the means described below. In the description of the means, in order to clarify the correspondence between the description of [Claims] and the description of [Best Mode for Carrying Out the Invention], [Best Mode for Carrying Out the Invention] ] Is added with the numbers and symbols used in []. However, the added number / symbol should not be used to limit the technical scope of the invention described in [Claims].

  The battery according to the present invention includes an exterior body (1, 1A), a positive terminal (3) attached to the exterior body (1, 1A), and a negative terminal (2) attached to the exterior body (1, 1A). And a connecting mechanism (6-9, 16-19) for electrically connecting the positive terminal (3) and the negative terminal (2). In the connection mechanism (6-9, 16-19), when the specific member (6, 8, 18) is melted by the temperature rise of the battery, the positive electrode terminal (3) and the negative electrode terminal (2) are electrically connected. It is comprised so that. In the battery having such a configuration, when the temperature rises, self-discharge is started, and thereby the battery can be returned to a safer state.

  In a preferred embodiment, the surface of at least a part of the exterior body (1, 1A) is conductive, the connection mechanism (6-9) is joined to the negative electrode terminal (2), and the tip portion is the exterior body. A first conducting member (6) urged toward the body (1, 1A), and provided between the first conducting member (6) and the exterior body (1, 1A); A first insulating member (7) configured to be meltable, and the connection mechanism (6-9) is configured such that when the first insulating member (7) is melted, the first conductive member (6) is 1, 1A), and the positive electrode terminal (3) and the negative electrode terminal (2) are electrically connected through the first conductive member (6) and the exterior body (1, 1A).

  In order to control the short circuit current flowing between the positive terminal (3) and the negative terminal (2), it is preferable that the first conduction member (6) includes a resistance element (14).

  In one embodiment, the connection mechanism (6-9) is further joined to the positive terminal (3) and the second conductive member (8) whose tip is urged toward the exterior body (1, 1A); And a second insulating member (9) provided between the second conducting member (8) and the exterior body (1, 1A) and configured to be meltable by the temperature rise of the battery.

  Instead, the positive electrode terminal (3) may be directly connected to the exterior body (1, 1A) through a lead wire or via a resistance element (15).

  The first insulating member (7) is preferably made of an insulating material having a melting point lower than the temperature at which the battery causes thermal runaway, and the battery further includes a safety valve (not shown). In addition, the melting point of the first insulating member (7) is preferably lower than the temperature at which the safety valve operates.

  Preferably, the first insulating member (7) is made of polyethylene glycol, crotonic acid, or solid paraffin having an average molecular weight of 1000 or more.

  In another preferred embodiment, the connection mechanism (18, 19) is provided in the vicinity of the negative electrode terminal (2), and is an alloy piece (18) made of a low melting point alloy that can be melted by the temperature rise of the battery. ) And an outflow prevention member (19) provided so as to surround the alloy piece (18). When the alloy piece (18) melts, the outflow prevention member (19) electrically connects the negative electrode terminal (2) and the exterior body (1, 1A) by a liquid alloy formed by melting the alloy piece (18). It is formed to hold the liquid alloy to be connected. When the alloy piece (18) is melted, the connection mechanism (18, 19) electrically connects the positive electrode terminal (3) and the negative electrode terminal (2) via the liquid alloy and the outer package (1, 1A). Connecting. The alloy piece (18) preferably has a melting point lower than the temperature at which the battery causes thermal runaway. When the battery further includes a safety valve, the melting point of the alloy piece (18) is such that the safety valve is activated. Desirably lower than the temperature.

  The power supply system according to the present invention includes the exterior body (1, 1A) having at least a part of a conductive surface, and a positive terminal (3) and a negative terminal (2) attached to the exterior body (1, 1A). And a connection mechanism (6-9) for electrically connecting the positive electrode terminal (3) and the negative electrode terminal (2), the connection mechanism (6-9) being joined to the negative electrode terminal (2), A first conducting member (6) whose tip is urged toward the exterior body (1, 1A), and provided between the first conducting member (6) and the exterior body (1, 1A); This is for controlling the operation of the battery (10) including the first insulating member (7) configured to be meltable by the temperature rise of the battery. The power supply system includes a control circuit (21), and the control circuit (21) includes a voltage between the negative terminal (2) and the exterior body (1, 1A), the negative terminal (2) and the exterior. The current flows between the body (1, 1A), the voltage drop generated in the first conduction member (6), the current flowing through the first conduction member (6), or the temperature of the first conduction member (6). The melting of the insulating member (7) is detected, and the operation of the battery (10) is controlled according to the presence or absence of the melting of the first insulating member (7).

  Such a power supply system can quickly detect the melting of the first insulating member (7) and can optimally operate the battery (10).

  Another power supply system according to the present invention includes an exterior body (1, 1A) having at least a part of a conductive surface, and a positive terminal (3) and a negative terminal (2) attached to the exterior body (1, 1A). ) And the positive electrode terminal (3) and the negative electrode terminal (2) are electrically connected, and the connection mechanism (18, 19) is close to the negative electrode terminal (2). A battery comprising an alloy piece (18) made of a low melting point alloy that can be melted by a rise in temperature of the battery, and an outflow prevention member (19) provided so as to surround the alloy piece (18) This is for controlling the operation of (10). The other power supply system includes a control circuit (21), and the control circuit (21) includes a voltage between the negative electrode terminal (2) and the exterior body (1, 1A), a negative electrode terminal (2), and The melting of the alloy piece (18) is detected by the current flowing between the exterior body (1, 1A) or the voltage between the alloy piece (18) and the exterior body (1, 1A). The operation of the battery (10) is controlled in accordance with the presence or absence of melting in 18).

  Such a power supply system can quickly detect the melting of the alloy piece (18) and optimally operate the battery (10).

  ADVANTAGE OF THE INVENTION According to this invention, when temperature rises, the self discharge can be started and the technique for returning a battery to a safer state by this can be provided.

(First embodiment)
FIG. 1 is a side view showing a configuration of a lithium ion secondary battery 10 according to the first embodiment of the present invention. A lithium ion secondary battery 10 of the first embodiment includes a container 1 used as an exterior body and two electrode terminals: a negative electrode terminal 2 and a positive electrode terminal 3 attached to the lid 1a of the container 1. Yes. In the present embodiment, at least the surface of the lid portion 1a of the container 1 has conductivity. The container 1 (and its lid 1a) is most typically formed of iron or aluminum. The negative electrode terminal 2 and the positive electrode terminal 3 are attached to the container 1 by packings 4 and 5, respectively. The packings 4 and 5 are insulative.

  The lithium ion secondary battery 10 of the present embodiment is provided with a conductive member 6 and an insulating member 7 corresponding to the negative electrode terminal 2 and corresponding to the positive electrode terminal 3 in order to advance self-discharge when the temperature rises. Thus, a conducting member 8 and an insulating member 9 are provided. The conducting member 6 is physically and electrically joined to the negative electrode terminal 2. The insulating member 7 is joined to the tip of the conducting member 6 and is sandwiched between the conducting member 6 and the lid 1 a of the container 1. Similarly, the conductive member 8 is physically and electrically joined to the positive electrode terminal 3. The insulating member 9 is sandwiched between the conducting member 6 and the lid portion 1 a of the container 1.

  The conducting members 6 and 8 are made of a material having conductivity and high elasticity, and the leading end of the conducting member 6 is urged toward the lid portion 1a of the container 1 by its own elasticity. Yes. The conducting members 6 and 8 can be formed of a metal material, or can be formed of a resin material containing carbon. Further, the conducting members 6 and 8 can take either a band shape or a needle shape.

The insulating members 7 and 9 are made of an insulating material having a melting point that is higher than the allowable operating temperature (for example, 60 ° C.) of the lithium ion secondary battery 10 and lower than the temperature at which the lithium ion secondary battery 10 causes thermal runaway. Has been. The insulating members 7 and 9 are made of, for example, polyethylene glycol (melting point 63 to 65 ° C.) having an average molecular weight of 1000 or more, crotonic acid (melting point 71 ° C.), and solid paraffin having a melting point of 68 to 70 ° C. It should be noted that solid paraffin is a general term for alkanes having 20 or more carbon atoms (general formula: C _n H _{2n + 2} ).

  The conductive members 6 and 8 and the insulating members 7 and 9 electrically connect the negative electrode terminal 2 and the positive electrode terminal 3 when the temperature of the lithium ion secondary battery 10 rises (for example, due to overcharging), thereby It functions as a safety mechanism that initiates self-discharge. FIG. 2 is a diagram illustrating the operation of the conducting member 6 and the insulating member 7 provided corresponding to the negative electrode terminal 2 when the temperature rises. When the temperature of the lithium ion secondary battery 10 rises, the insulating member 7 is dissolved, and the leading end portion of the conducting member 6 comes into contact with the lid portion 1a of the container 1 due to the elasticity of the conducting member 6 itself. Thereby, the negative electrode terminal 2 is electrically connected to the cover part 1a. Similarly, when the temperature of the lithium ion secondary battery 10 rises on the positive electrode terminal 3 side, the insulating member 9 is melted and the leading end of the conductive member 8 comes into contact with the lid portion 1a of the container 1, whereby the positive electrode terminal 3 is electrically connected to the lid 1a. As a result, the negative electrode terminal 2 and the positive electrode terminal 3 are electrically connected via the lid portion 1a, and self-discharge is started. When the self-discharge is started, the voltage between the negative electrode terminal 2 and the positive electrode terminal 3 is lowered, thereby improving safety.

  Electrical connection between the negative electrode terminal 2 and the positive electrode terminal 3 when the temperature rises is also effective in suppressing the current flowing into the lithium ion secondary battery 10 when overcharging is performed. . When the negative electrode terminal 2 and the positive electrode terminal 3 are electrically connected by the conducting members 6 and 8 and the lid portion 1a, the current supplied to the lithium ion secondary battery 10 is bypassed to the conducting members 6 and 8 and the lid portion 1a. Thus, the current flowing into the lithium ion secondary battery 10 is suppressed. Suppressing the current flowing into the lithium ion secondary battery 10 is effective for suppressing the temperature rise of the lithium ion secondary battery 10 and improving safety.

  The melting points of the insulating members 7 and 9 are higher than the allowable operating temperature (for example, 60 ° C.) of the lithium ion secondary battery 10, and the temperature at which a safety valve (not shown) provided in the lithium ion secondary battery 10 operates (typically Specifically, it is preferably lower than 80 to 90 ° C. When the safety valve is activated, gas is ejected. Therefore, as long as there is no problem with safety, the operation of the safety valve should be avoided. By making the temperature at which the insulating members 7 and 9 melt lower than the temperature at which the safety valve operates, the operation of the safety valve can be delayed while maintaining safety. Material group of the insulating members 7 and 9 described above: polyethylene glycol having an average molecular weight of 1000 or more (melting point 63 to 65 ° C.), crotonic acid (melting point 71 ° C.), solid paraffin having a melting point of 68 to 70 ° C. It is a material that satisfies such requirements, and is suitable as a material for the insulating members 7 and 9.

  When the negative electrode terminal 2 and the positive electrode terminal 3 are electrically connected, the short-circuit current flowing between them needs to be adjusted appropriately. When an excessively large short-circuit current flows, large Joule heat is generated, which is not preferable from the viewpoint of safety. One method for controlling the magnitude of the short-circuit current flowing between the negative electrode terminal 2 and the positive electrode terminal 3 is to appropriately select the material of the conducting members 6 and 8. If a material with low conductivity is used as the conducting members 6 and 8, the short circuit current is reduced, and if a material with high conductivity is used as the conducting members 6 and 8, the short circuit current is increased.

  In order to more positively adjust the short-circuit current, it is effective to insert a resistance element in the conducting member. FIG. 3 shows the structure of the conductive member 6A having such a configuration. The conducting member 6A in FIG. 3 includes conductive pieces 12 and 13 and a resistance element 14 connected therebetween. The conductive piece 12 is joined to the negative electrode terminal 2. The conductive piece 13 is made of a highly elastic material and is urged toward the container 1 by its own elasticity. The resistance value of the resistance element 14 is appropriately determined according to the desired magnitude of the short-circuit current. When the insulating member 7 is melted, the tip of the conductive piece 13 comes into contact with the lid portion 1a of the container 1, whereby the negative electrode terminal 2 is electrically connected to the lid portion 1a. The structure of the conducting member shown in FIG. 3 can be applied not to the conducting member joined to the negative terminal 2 but to the conducting member 8 joined to the positive terminal 3.

  The structure in which the resistance element is inserted into the conducting member is preferable not only from the viewpoint of controlling the short-circuit current but also from the viewpoint of limiting the position where Joule heat is generated. In the configuration in which the resistance element is inserted into the conducting member, Joule heat due to the short-circuit current is substantially generated only in the resistance element. This is effective in controlling the generation of heat. In a configuration in which Joule heat is generated only by the resistance element, generation of Joule heat can be easily dealt with by securing a heat dissipation path of the resistance element or by actively cooling the resistance element.

  1 and 3 illustrate a configuration in which the conducting members 6 and 8 and the insulating members 7 and 9 are provided outside the container 1, the conducting members 6 and 8 and the insulating members 7 and 9 are provided. It can also be provided inside the container 1. FIG. 4 shows a structure in the vicinity of the negative electrode terminal 2 in which the conducting member 6 and the insulating member 7 are provided inside the container 1. In one embodiment, the diameter of the end 2 a located inside the container 1 of the negative electrode terminal 2 is increased, and the conducting member 6 and the current collector foil 11 are sandwiched between the end 2 a and the packing 4. The insulating member 7 is provided between the conducting member 6 and the inner surface of the lid 1 a of the container 1. When the temperature rises, the leading end of the conducting member 6 is pressed against the lid 1a by the elasticity of the conducting member 6 itself, and the negative electrode terminal 2 is electrically connected to the lid 1a. A similar structure can be adopted for the positive terminal 3.

  FIG. 1 illustrates a configuration in which a safety mechanism in which conductive members 6 and 8 and insulating members 7 and 9 are combined is used for both the negative electrode terminal 2 and the positive electrode terminal 3. A safety mechanism that combines a conducting member and an insulating member may be employed only on one side. In this case, the other electrode terminal is directly connected to the lid portion 1a of the container 1 by a lead wire, or is connected to the lid portion 1a of the container 1 via a resistance element. In FIG. 5, a safety mechanism in which the conductive member 6 and the insulating member 7 are combined is adopted for the negative electrode terminal 2, while the positive electrode terminal 3 is electrically connected to the lid portion 1 a of the container 1 through the resistance element 15. The configuration is shown. One lead of the resistance element 15 is joined to the positive terminal 3 and the other lead is joined to the lid portion 1a. Even in this case, when the temperature of the lithium ion secondary battery 10 rises and the insulating member 7 melts, the negative electrode terminal 2 and the positive electrode terminal 3 are electrically connected, and self-discharge is started. Note that in the configuration of FIG. 5, the positive terminal 3 is always electrically connected to the lid 1 a of the container 1.

  It should be noted that when the electrode terminal and the lid portion 1a of the container 1 are electrically connected by the lead wire, they have the same potential. In particular, when the negative electrode terminal 2 is connected to the lid portion 1a of the container 1 by a lead wire or via the resistance element 15, the container 1 (or its lid portion 1a) is at a base potential with respect to the positive electrode terminal 3 during normal operation. Depending on the material of the container 1, undesirable phenomena such as corrosion due to lithium deposition may occur. In order to avoid such a situation, as shown in FIG. 5, a safety mechanism in which the conductive member 6 and the insulating member 7 are combined with respect to the negative electrode terminal 2 is adopted, while the positive electrode terminal 3 is connected by a lead wire. Or the structure connected to the cover part 1a of the container 1 via the resistive element 15 is suitable.

  When the surface of the lid 1a of the container 1A is insulative, as shown in FIG. 6A, one of the conducting members 6 and 8 is arranged so as to overlap the other, and the conducting members 6 and 8 are disposed. It is also possible to provide an insulating member 16 that melts as the temperature rises. When the temperature of the lithium ion secondary battery 10 rises, the insulating member 16 is dissolved, the negative electrode terminal 2 and the positive electrode terminal 3 are electrically connected, and self-discharge is started.

  Instead, as shown in FIG. 6B, the conducting member 17 is provided on the lid 1 a of the container 1 </ b> A, and the insulating members 7 and 9 are provided between the conducting members 6 and 8 and the conducting member 17. Is also possible. When the temperature of the lithium ion secondary battery 10 rises, the insulating members 7 and 9 are melted and the conducting members 6 and 8 and the conducting member 17 are electrically connected. Thereby, the negative electrode terminal 2 and the positive electrode terminal 3 are electrically connected via the conducting members 6 and 8 and the conducting member 17, and self-discharge is started.

  In the present embodiment, a structure in which the conducting members 6 and 8 are urged to the lid portion 1a of the container 1 by its own elasticity is presented, but means for urging the distal ends of the conducting members 6 and 8 is presented. Is not limited to this. A biasing mechanism such as a spring is joined to the leading end portions of the conducting members 6 and 8, and the conducting member 6 can be biased toward the lid portion 1 a of the container 1 by the biasing mechanism.

(Second Embodiment)
FIG. 7 is a side view showing the configuration of the lithium ion secondary battery 10 of the second embodiment, and FIG. 8 is a top view. 7 and 8 particularly show the structure of the portion in the vicinity of the negative electrode terminal 2. As shown in the left diagram of FIG. 7, an alloy piece 18 formed of a low melting point alloy is provided in the vicinity of the negative electrode terminal 2 of the container 1, and as shown in FIG. The piece 18 is surrounded by an outflow prevention member 19. It should be noted that the alloy piece 18 is disposed away from the negative electrode terminal 2 in a state where normal operation is performed. Similarly, the configuration shown in FIGS. 7 and 8 is adopted for the positive electrode terminal 3. Instead of adopting the configuration shown in FIGS. 7 and 8, the positive electrode terminal 3 is electrically connected to the lid portion 1 a directly by a lead wire or via a resistance element, as in the first embodiment. May be.

The alloy piece 18 is made of an alloy material having a melting point that is higher than the allowable operating temperature (for example, 60 ° C.) of the lithium ion secondary battery 10 and lower than the temperature at which the lithium ion secondary battery 10 causes thermal runaway. The alloy piece 18 can be formed of, for example, an alloy of tin (Sn), bismuth (Bi), lead (Pb), and cadmium (Cd). If the composition of tin (Sn), bismuth (Bi), lead (Pb), and cadmium (Cd) contained in the alloy piece 18 is as follows, the melting point of the alloy piece 18 can be about 70 ° C. Preferred (all in weight percent):
Sn: 11.3-12.5%
Pb: 25.0-37.7%
Cd: 8.5 to 12.5%
Bi and inevitable impurities: balance

  In the configuration of the second embodiment, as shown in the right diagram of FIG. 7, when the temperature of the lithium ion secondary battery 10 rises, the alloy piece 18 melts, and the negative electrode terminal 2 melts the alloy piece 18. The liquid alloy thus formed is electrically connected to the lid 1a of the container 1. At this time, the outflow prevention member 19 holds the liquid alloy so that the negative electrode terminal 2 and the lid portion 1a are electrically connected by a liquid alloy formed by melting the alloy piece 18. When the configuration of FIG. 7 is also adopted for the positive terminal 3, the positive terminal 3 is also electrically connected to the lid portion 1 a of the container 1 by a liquid alloy formed by melting the alloy piece 18. Thereby, the negative electrode terminal 2 and the positive electrode terminal 3 are electrically connected, and self-discharge is automatically started. Starting the self-discharge automatically is effective for improving the safety of the lithium ion secondary battery 10.

  The melting point of the alloy piece 18 is higher than an allowable operating temperature (for example, 60 ° C.) of the lithium ion secondary battery 10, and a temperature at which a safety valve (not shown) provided in the lithium ion secondary battery 10 operates (typically Is preferably lower than 80 to 90 ° C. By making the melting point of the alloy piece 18 lower than the temperature at which the safety valve operates, the operation of the safety valve can be delayed while maintaining safety as in the first embodiment.

  The structure of the alloy piece 18 and the outflow prevention member 19 is such that when the alloy piece 18 is melted, the negative electrode terminal 2 (and the positive electrode terminal 3) is electrically connected to the lid portion 1a of the container 1, and the alloy piece 18 is Any structure that does not flow out can be changed in various ways.

(Operation method of lithium ion secondary battery)
In the power supply system incorporating the lithium ion secondary battery 10 of the above-described embodiment, it is preferable to detect that the insulating members 7 and 9 or the alloy pieces 18 are dissolved in the operation. When the insulating members 7 and 9 or the alloy pieces 18 are melted, it is considered that there is some abnormality in the lithium ion secondary battery 10, and therefore it is desirable to stop the operation.

  FIG. 9 is a diagram illustrating an example of a configuration of a power supply system in which the lithium ion secondary battery 10 is incorporated. The power supply system of FIG. 9 includes a control circuit 21, a sensor 22, and an interlock switch 23. The control circuit 21 uses the sensor 22 to monitor the voltage between the positive electrode terminal 3 and the negative electrode terminal 2 of the lithium ion secondary battery 10, the current flowing through the lithium ion secondary battery 10, and the temperature of the lithium ion secondary battery 10. If necessary, the interlock switch 23 is shut off to stop the operation of the power supply system. Although only one sensor 22 is shown in FIG. 9, it should be understood that there are actually a sufficient number and types of sensors 22 to obtain parameters necessary for operation control. It is.

  As described above, the lithium ion secondary battery 10 is configured so that the positive electrode terminal 3 and the negative electrode terminal 2 are electrically connected when the temperature rises. If the voltage between them is monitored, it can be detected that the insulating members 7 and 9 or the alloy piece 18 has melted. One problem with such a detection method is that even if the insulating members 7 and 9 or the alloy pieces 18 are melted, the voltage between the positive electrode terminal 3 and the negative electrode terminal 2 due to the electromotive force of the lithium ion secondary battery 10 itself. May not change abruptly, so that it may not be possible to quickly detect that the insulating members 7 and 9 or the alloy piece 18 has melted. Below, the method for detecting rapidly that the insulating members 7 and 9 or the alloy piece 18 melt | dissolved is shown.

  In one embodiment, as shown in FIG. 10, the melting of the insulating member 7 is detected by measuring the voltage V between the negative electrode terminal 2 and the lid portion 1 a of the container 1 using the sensor 22. When the insulating member 7 is not dissolved, the voltage between the negative electrode terminal 2 and the lid portion 1a of the container 1 takes a value in a certain normal range. When the insulating member 7 is dissolved, the voltage between the negative electrode terminal 2 and the lid portion 1a of the container 1 quickly shows an abnormal value that is out of the normal range. Therefore, by monitoring the voltage between the negative electrode terminal 2 and the lid portion 1a of the container 1, it is possible to quickly detect that the insulating member 7 has been dissolved. The melting of the insulating member 7 can also be detected from the time change rate dV / dt of the voltage V between the negative electrode terminal 2 and the lid 1 a of the container 1.

  Similarly, when the conductive member 8 and the insulating member 9 are provided corresponding to the positive electrode terminal 3, the voltage between the positive electrode terminal 3 and the lid portion 1 a of the container 1 is measured to dissolve the insulating member 9. Can be detected promptly.

  The method of measuring the voltage between the negative electrode terminal 2 (or the positive electrode terminal 3) and the lid portion 1a of the container 1 is the same as that of the second embodiment in that the negative electrode terminal 2 (or the positive electrode terminal 3) and the lid of the container 1 are measured. The case where the part 1a is electrically connected by the molten alloy piece 18 can be similarly applied. Also in this case, the melting of the alloy piece 18 is detected from the value of the voltage V between the negative electrode terminal 2 (or the positive electrode terminal 3) and the lid 1a of the container 1 or the time change rate dV / dt of the voltage V. Is possible.

  Further, as shown in FIG. 6B, when the conductive member 17 is provided in the insulating container 1A, the value of the voltage V between the negative electrode terminal 2 (or the positive electrode terminal 3) and the conductive member 17, Alternatively, it is possible to detect melting of the insulating member 7 (or the insulating member 9) from the time change rate dV / dt of the voltage V.

  Further, by measuring the current I flowing between the negative electrode terminal 2 and the lid portion 1 a of the container 1 by the sensor 22, it is possible to detect the dissolution of the insulating member 7. When the insulating member 7 is not dissolved, the current I flowing between the negative electrode terminal 2 and the lid portion 1a of the container 1 is zero. On the other hand, when the insulating member 7 is melted, the current I flowing between the negative electrode terminal 2 and the lid portion 1a of the container 1 immediately shows an abnormal value that is not zero. Therefore, by monitoring the current I flowing between the negative electrode terminal 2 and the lid portion 1a of the container 1, it is possible to quickly detect that the insulating member 7 has dissolved. The current I flowing between the negative electrode terminal 2 and the lid 1 a of the container 1 can be indirectly measured by measuring the magnetic field generated by the current I. The dissolution of the insulating member 7 can also be detected from the time change rate dI / dt of the current I flowing between the negative electrode terminal 2 and the lid portion 1 a of the container 1.

  Similarly, when the conductive member 8 and the insulating member 9 are provided corresponding to the positive electrode terminal 3, similarly, the current between the positive electrode terminal 3 and the lid 1 a of the container 1 is measured to dissolve the insulating member 9. Can be detected promptly.

  The method of measuring the current flowing between the negative electrode terminal 2 (or positive electrode terminal 3) and the lid 1a of the container 1 is the same as that of the second embodiment in that the negative electrode terminal 2 (or positive electrode terminal 3) and the container 1 are The same applies to the case where the lid portion 1a is electrically connected by the molten alloy piece 18. Also in this case, the melting of the alloy piece 18 is detected from the value of the current I between the negative electrode terminal 2 (or the positive electrode terminal 3) and the lid 1a of the container 1 or the time change rate dI / dt of the voltage I. Is possible.

Further, as shown in FIG. 11, for the lithium ion secondary battery 10 of the first embodiment, the melting of the insulating member 7 is detected by measuring the voltage drop V _drop generated in the conducting member 6. Is possible. When the insulating member 7 is not melted, no current flows through the conducting member 6, so the voltage drop V _drop generated at the conducting member 6 is 0V. On the other hand, when the insulating member 7 is melted, a current flows through the conducting member 6, so that the voltage drop V _drop generated in the conducting member 6 quickly takes an abnormal value other than zero. Therefore, by monitoring the voltage drop V _drop generated in the conducting member 6, it is possible to quickly detect that the insulating member 7 has dissolved. Such a method is particularly effective when the resistance element 14 is inserted into the conducting member 6A as shown in FIG. The melting of the insulating member 7 can also be detected from the time change rate dV _drop / dt of the voltage drop V _drop generated in the conducting member 6.

  Similarly, when the conductive member 8 and the insulating member 9 are provided corresponding to the positive electrode terminal 3, the dissolution of the insulating member 9 can be quickly detected by measuring the voltage drop generated in the conductive member 8. .

  Regarding the lithium ion secondary battery 10 of the first embodiment, it is also possible to detect the melting of the insulating member 7 by measuring the current flowing through the conducting member 6. When the insulating member 7 is not dissolved, the current flowing through the conducting member 6 is zero. On the other hand, when the insulating member 7 is melted, the current flowing through the conducting member 6 immediately shows an abnormal value other than zero. Therefore, by monitoring the current flowing through the conducting member 6, it can be quickly detected that the insulating member 7 has dissolved. The current flowing through the conducting member 6 can be indirectly measured by measuring the magnetic field generated by the current. The melting of the insulating member 7 can also be detected from the time change rate dI / dt of the current flowing through the conducting member 6.

  Similarly, when the conductive member 8 and the insulating member 9 are provided corresponding to the positive electrode terminal 3, the dissolution of the insulating member 9 can be quickly detected by measuring the current flowing through the conductive member 8.

  In addition, for the lithium ion secondary battery 10 of the first embodiment, it is also possible to detect the melting of the insulating member 7 by measuring the temperature T of the conducting member 6. When the insulating member 7 is not dissolved, the temperature T of the conducting member 6 is within a certain normal range. On the other hand, when the insulating member 7 is melted, a current flows through the conducting member 6, and the temperature of the conducting member 6 rises due to Joule heat. Therefore, the temperature T of the conducting member 6 quickly shows an abnormal value. Therefore, by monitoring the temperature T of the conducting member 6, it is possible to quickly detect that the insulating member 7 has dissolved. The melting of the insulating member 7 can also be detected from the time change rate dT / dt of the temperature T of the conductive member 6.

  On the other hand, for the lithium ion secondary battery 10 of the second embodiment, as shown in FIG. 12, by measuring the voltage between the alloy piece 18 and the lid 1a of the container 1, the alloy piece It is also possible to detect 18 melting. In this case, a voltage sensor is used as the sensor 22, and one terminal 22a of the sensor 22 is in contact with the alloy piece 18 when the alloy piece 18 is not melted, and is separated from the alloy piece 18 when the alloy piece 18 is melted. It is provided in such a position. In a state where the alloy piece 18 is not melted, the voltage between the alloy piece 18 detected by the sensor 22 and the lid portion 1a of the container 1 is in a predetermined normal range. When the alloy piece 18 is melted, one terminal 22a of the sensor 22 is in a floating state, so that the voltage measured by the sensor 22 quickly shows an abnormal value. Therefore, by monitoring the voltage between the alloy piece 18 and the lid portion 1a of the container 1, it is possible to quickly detect that the alloy piece 18 has melted.

  Although various embodiments of the present invention have been described above, the present invention should not be interpreted as being limited to the above-described embodiments. In particular, in the above-described embodiment, a lithium ion secondary battery has been described. However, it will be apparent to those skilled in the art that the present invention is applicable to other batteries in which thermal runaway may occur. .

FIG. 1 is a side view showing the configuration of the lithium ion secondary battery according to the first embodiment of the present invention. FIG. 2 is a side view showing the operation of the lithium ion secondary battery of the first embodiment. FIG. 3 is a side view showing another configuration of the lithium ion secondary battery of the first embodiment. FIG. 4 is a side view showing still another configuration of the lithium ion secondary battery according to the first embodiment. FIG. 5 is a side view showing still another configuration of the lithium ion secondary battery according to the first embodiment. FIG. 6A is a side view showing still another configuration of the lithium ion secondary battery of the first embodiment. FIG. 6B is a side view showing still another configuration of the lithium ion secondary battery of the first embodiment. FIG. 7 is a side view showing the configuration of the lithium ion secondary battery according to the second embodiment of the present invention. FIG. 8 is a top view showing the configuration of the lithium ion secondary battery according to the second embodiment of the present invention. FIG. 9 is a block diagram showing a configuration of a power supply system incorporating the lithium ion secondary battery of the present invention. FIG. 10 is a diagram showing an example of the operation of the power supply system of the lithium ion secondary battery of the present invention. FIG. 11 is a diagram showing an example of the operation of the power supply system of the lithium ion secondary battery of the present invention. FIG. 12 is a diagram showing an example of the operation of the lithium ion secondary battery power supply system of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A: Container 1a: Cover part 2: Negative electrode terminal 3: Positive electrode terminal 4, 5: Packing 6, 6A, 8: Conductive member 7, 9: Insulating member 10: Lithium ion secondary battery 11: Current collector foil 12, 13: Conductive piece 14: Resistance element 15: Resistance element 16: Insulating member 17: Conductive member 18: Alloy piece 19: Outflow prevention member 21: Control circuit 22: Sensor 23: Interlock switch

Claims (13)

An exterior body,
A positive electrode terminal attached to the exterior body;
A negative electrode terminal attached to the exterior body;
A battery comprising a connection mechanism for electrically connecting the positive terminal and the negative terminal,
The connection mechanism is configured such that the positive electrode terminal and the negative electrode terminal are electrically connected when the specific member melts due to a temperature rise of the battery. The battery according to claim 1,
The surface of at least a part of the exterior body is conductive,
The connection mechanism is
A first conducting member joined to the negative electrode terminal and having a tip urged toward the exterior body;
A first insulating member provided between the first conducting member and the exterior body and configured to be meltable by a rise in temperature of the battery;
The connection mechanism is configured such that when the first insulating member is melted, the first conductive member contacts the exterior body, and the positive electrode terminal and the negative electrode terminal are electrically connected to each other via the first conductive member and the exterior body. Connect to the battery. The battery according to claim 2,
The first conductive member includes a resistance element. The battery according to claim 2,
The connection mechanism further includes:
A second conductive member joined to the positive electrode terminal and having a tip urged toward the exterior body;
A battery including a second insulating member provided between the second conducting member and the exterior body and configured to be meltable by a temperature rise of the battery. The battery according to claim 2,
Furthermore,
The positive electrode terminal is a battery connected to the exterior body directly by a lead wire or via a resistance element. The battery according to claim 2,
The first insulating member is made of an insulating material having a melting point lower than a temperature at which the battery causes thermal runaway. The battery according to claim 6,
Furthermore,
Equipped with a safety valve,
The melting point of the first insulating member is lower than the temperature at which the safety valve operates. The battery according to claim 2,
The first insulating member is a battery made of polyethylene glycol having an average molecular weight of 1000 or more, crotonic acid, or solid paraffin. The battery according to claim 1,
The connection mechanism is
An alloy piece made of a low melting point alloy provided close to the negative electrode terminal and meltable by the temperature rise of the battery;
An outflow prevention member provided so as to surround the alloy piece,
The outflow prevention member holds the liquid alloy so that when the alloy piece is melted, the negative electrode terminal and the exterior body are electrically connected by a liquid alloy formed by melting the alloy piece. Formed,
When the alloy piece is melted, the connection mechanism electrically connects the positive electrode terminal and the negative electrode terminal via the liquid alloy and the outer package. The battery according to claim 9,
The alloy piece has a melting point lower than a temperature at which the battery causes thermal runaway. The battery according to claim 10,
Furthermore,
Equipped with a safety valve,
The melting point of the alloy piece is lower than the temperature at which the safety valve operates. A battery according to claim 2;
A control circuit,
The control circuit includes a voltage between the negative electrode terminal and the outer package, a current flowing between the negative electrode terminal and the outer package, a voltage drop generated in the first conductive member, and a current flowing through the first conductive member. Alternatively, a power supply system that detects the melting of the first insulating member based on the temperature of the first conductive member and controls the operation of the battery according to the presence or absence of the melting of the first insulating member. A battery according to claim 9;
A control circuit,
The control circuit is configured such that a voltage between the negative electrode terminal and the exterior body, a current flowing between the negative electrode terminal and the exterior body, or a voltage between the alloy piece and the exterior body A power supply system that detects melting and controls operation of the battery according to whether or not the alloy pieces are melted.

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