JP2006339017A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack, where the generation of thermal runaway of a secondary battery built in is prevented and inducing the thermal runaway of other secondary battery due to this thermal runaway is prevented effectively. <P>SOLUTION: The battery pack is provided with a thermorunaway preventing wall 3 of plastic formed integrally with a heat conduction cylinder 4 between secondary batteries 1 housed in a case 2. The heat conduction cylinder 4, having a clearance of 0.5 mm or smaller between its inner face and the outer face of the secondary battery 1, has the surface of the secondary battery 1, in contact with the inner face of the thermorunaway preventing wall 3 in surface contact state. The plastic forming the thermorunaway preventing wall 3 has a thermal conductivity of 0.05 W/m K or higher and 3 W/m K or lower. Furthermore, the thermorunaway preventing wall 3 has a thickness of 0.5 mm or larger and 3 mm or smaller. In the battery pack, the radiant heat of an exothermic secondary battery 1A is cut off by the thermorunaway preventing wall 3, and the generated heat of the exothermic secondary battery 1A is thermally conducted to the neighboring secondary battery 1B, and the exothermic secondary battery 1A is heat radiated, and the thermal runaway of the exothermic secondary battery 1A is prevented from being transmitted to the adjacent secondary battery 1B. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an assembled battery including a plurality of secondary batteries, in which a thermal runaway of a secondary battery does not induce a thermal runaway of another secondary battery.

  The secondary battery may cause thermal runaway due to various causes such as internal short circuit or overcharge. When thermal runaway occurs, the temperature of the battery rises rapidly and may be 300 ° C. to 400 ° C. or higher. In particular, in a battery pack incorporating a large number of secondary batteries, when a plurality of secondary batteries cause a thermal runaway, the energy of the thermal runaway becomes extremely large, which makes the battery more dangerous. In order to prevent such an adverse effect, a technique for preventing thermal runaway of the secondary battery has been developed (see Patent Documents 1 to 3).

  As a technique for preventing thermal runaway of a secondary battery, a technique for preventing thermal runaway by providing it in the secondary battery itself (see Patent Document 1) and a technique for preventing thermal runaway by providing it outside the secondary battery (Patent Document) 2 and 3) have been developed.

  As described in Patent Document 1, since a secondary battery having a mechanism for preventing thermal runaway needs to change the configuration of the secondary battery itself, the secondary battery already manufactured and sold. Cannot be used as a battery pack. For this reason, since it is necessary to manufacture a special secondary battery, it is not practical.

  The assembled battery described in Patent Document 2 changes the arrangement of the batteries. That is, the safety valves of adjacent batteries are arranged on different sides. In this assembled battery, it is difficult to ignite the vaporized electrolyte vapor released from the safety valve due to a thermal runaway of one battery, and safety can be improved. However, this structure can prevent the ignition of the electrolyte vapor, but in the assembled battery in which the batteries are arranged close to each other, it cannot prevent the adjacent battery from causing the thermal runaway due to the heat of the thermal runaway battery.

  When the internal pressure rises and the outer case swells, the secondary battery of Patent Document 3 is provided with a mechanism that prevents the thermal runaway by turning on the switch and causing a short-circuit current to flow to discharge the battery. This mechanism cannot effectively prevent thermal runaway depending on the state of thermal runaway. For example, when a secondary battery near full charge is short-circuited internally and generates heat from the inside, the internal pressure rises and the switch is turned on and a short-circuit current flows. Both flow and a large discharge current flows. As described above, since the discharge current is further increased by the external short-circuit current, the secondary battery is likely to cause thermal runaway. Therefore, it is difficult to reliably prevent thermal runaway caused by various causes. In addition, since it is necessary to provide a mechanism that allows a short-circuit current to flow outside the secondary battery due to the bulging of the outer case, there is a drawback in that the structure is complicated and the outer shape becomes large when used in a battery pack incorporating a large number of secondary batteries. There is.

In addition to making it difficult for the secondary battery itself to cause thermal runaway, an assembled battery containing multiple secondary batteries can cause thermal runaway if any secondary battery causes thermal runaway. It is important not to induce thermal runaway of the battery.
JP 2004-303447 A JP 2003-303581 A JP 2004-319463 A

  As a result of repeating various experiments, the present inventors, in an assembled battery in which a plurality of secondary batteries are arranged close to each other, can control the radiant heat and heat conduction generated by the thermal runaway, thereby providing a secondary battery. As a result, we have developed a structure that will not cause thermal runaway of other secondary batteries even if any secondary battery causes thermal runaway. Accordingly, an important object of the present invention is to provide an assembled battery that can prevent the occurrence of thermal runaway of a built-in secondary battery and effectively prevent thermal runaway from causing thermal runaway of other secondary batteries. It is to provide.

The assembled battery of the present invention has the following configuration in order to achieve the above-described object.
The assembled battery houses a plurality of secondary batteries 1 in a case 2 adjacent to each other in a parallel posture. In the assembled battery, a plastic thermal runaway prevention wall 3 is provided between adjacent secondary batteries 1. The thermal runaway prevention wall 3 is integrally formed with a heat conduction cylinder 4 whose inner surface has a shape equal to the outer shape of the secondary battery 1. As a part. The heat conduction cylinder 4 has a clearance between its inner surface and the outer surface of the secondary battery 1 of 0.5 mm or less, and the surface of the secondary battery 1 is brought into contact with the inner surface of the thermal runaway prevention wall 3 in a surface contact state. Further, the plastic for molding the thermal runaway prevention wall 3 has a thermal conductivity of 0.05 W / m · K or more and 3 W / m · K or less. Furthermore, the thermal runaway prevention wall 3 has a thickness of 0.5 mm or more and 3 mm or less. The assembled battery blocks the radiant heat of the heat generating secondary battery 1A by the thermal runaway prevention wall 3 provided between the secondary batteries 1, but the heat generated by the heat generating secondary battery 1A is adjacent to the secondary battery 1B. The heat generating secondary battery 1A is dissipated to conduct heat, and the thermal runaway of the heat generating secondary battery 1A is prevented from being transmitted to the adjacent secondary battery 1B.

  The assembled battery of the present invention can divide the heat conducting cylinder 4 into a plurality in the middle in the axial direction.

  The assembled battery of the present invention can include an inner case 8 formed by connecting end plates 7 to both ends of the heat conducting cylinder 4. In the inner case 8, the heat conducting cylinder 4 is divided into two in the middle in the axial direction, divided into a pair of case units 8A, and the divided pair of case units 8A are connected to each other. Can be stored in the inner case 8.

  The heat conducting cylinder 4 can be formed in a tapered shape on the inner surface, and a portion protruding from the inner surface can be brought into surface contact with the surface of the secondary battery 1. The secondary battery 1 can be a lithium ion secondary battery 1.

  The assembled battery of the present invention can detect the temperature of the secondary battery 1 by providing an opening 5 in a part of the heat conducting cylinder 4 and disposing a temperature sensor 6 in the opening 5.

  In the assembled battery of the present invention, the secondary battery 1 is a cylindrical battery, and another secondary battery 1 is disposed between the valleys of the adjacent secondary batteries 1. The boundary region surrounded by the three secondary batteries 1 from the closest approach gap can be formed without any gap with the plastic forming the thermal runaway prevention wall 3.

  The assembled battery of the present invention has a feature that it can effectively prevent the thermal runaway from inducing the thermal runaway of other secondary batteries while preventing the occurrence of thermal runaway of the built-in secondary battery. In the assembled battery of the present invention, a plastic thermal runaway prevention wall is provided between adjacent secondary batteries. With this thermal runaway prevention wall, the heat transfer of the secondary battery that generates heat is in a specific state. This is because the heat transfer is controlled. In the assembled battery of the present invention, the thermal runaway prevention wall is formed integrally with the heat conducting cylinder, the clearance with the outer surface of the secondary battery is set to 0.5 mm or less, and the surface of the secondary battery is brought into contact with the surface in a surface contact state. In addition, the thermal conductivity of the plastic that forms the thermal runaway prevention wall is 0.05 W / m · K or more and 3 W / m · K or less, and the thickness of the thermal runaway prevention wall is 0.5 mm or more and 3 mm or less. Yes. The assembled battery with this structure blocks the radiant heat of the heat generating secondary battery by the thermal runaway prevention wall provided between the secondary batteries, but conducts heat from the heat generating secondary battery to the adjacent secondary battery. The heat generating secondary battery is dissipated. If the heat dissipation amount of the exothermic secondary battery is controlled to a specific amount of heat, the adjacent secondary battery will not be thermally runaway due to the heat dissipation of the exothermic secondary battery, and the temperature rise of the exothermic secondary battery is also limited to the maximum temperature Becomes lower. For this reason, the exothermic secondary battery is not overheated, and the adjacent secondary battery does not run out of heat. As described above, the assembled battery of the present invention controls the radiant heat and heat conduction of the heat generating secondary battery to make the heat dissipation of the heat generating secondary battery within a specific range, so that the heat generating secondary battery is adjacent. By limiting the amount of heat that heats the secondary battery and limiting the maximum temperature, it is possible to skillfully prevent thermal runaway of the adjacent secondary battery.

  Embodiments of the present invention will be described below with reference to the drawings. However, the example shown below illustrates the assembled battery for embodying the technical idea of the present invention, and the present invention does not specify the assembled battery as follows.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The assembled battery shown in FIG. 1 accommodates a plurality of secondary batteries 1 in a case 2 adjacent to each other in a parallel posture. The assembled battery in this figure houses eight secondary batteries 1. The assembled battery of the present invention does not specify the number of secondary batteries housed in the case as eight. For example, an assembled battery used for a power source of a hybrid car includes 100 or more secondary batteries.

  The assembled battery prevented thermal runaway due to a sudden rise in the temperature of the secondary battery due to an internal short circuit, etc., or in the worst case, even if any secondary battery caused thermal runaway, A unique configuration is provided to prevent the adjacent secondary battery from running away due to heat generated by the secondary battery. In order to realize this, the assembled battery has a structure that controls heat transfer between adjacent secondary batteries to a specific state. That is, as shown in the conceptual diagram of FIG. 2, the assembled battery blocks the heat of the exothermic secondary battery 1 </ b> A moving to the adjacent secondary battery 1 </ b> B by radiant heat by the thermal runaway prevention wall 3, With this thermal runaway prevention wall 3, the heat is transferred to the adjacent secondary battery 1 </ b> B by heat conduction by controlling to a specific heat transfer state.

  If the amount of heat conduction from the secondary battery that generates heat is too large or too small, thermal runaway of the secondary battery cannot be prevented. FIG. 3 is a graph showing the temperature rise characteristics of a heat generating secondary battery in which an internal short circuit causes a thermal runaway and a secondary battery adjacent thereto in an assembled battery having a large amount of heat conduction between secondary batteries. In this assembled battery, the surface of an adjacent secondary battery is brought into direct contact, and the heat of the heat-generating secondary battery that is thermally runaway is transferred to the adjacent secondary battery by both radiant heat and heat conduction. In this figure, a temperature rise of a heat generating secondary battery that is thermally runaway due to an internal short circuit is shown by a curve A, and a temperature rise of the adjacent secondary battery is shown by a curve B. In this assembled battery, the temperature of the exothermic secondary battery that causes thermal runaway rises to about 300 ° C. after 30 seconds, and the adjacent secondary battery induces thermal runaway after about 70 seconds, causing the temperature to rise rapidly. After a second, the temperature of the secondary battery in which the thermal runaway is induced rises to 500 ° C. In this assembled battery, if one of the secondary batteries is thermally runaway, the neighboring secondary battery is also triggered by thermal runaway. Therefore, in the assembled battery containing a plurality of secondary batteries, the heat of one secondary battery is Runaway causes all secondary batteries to run away.

  Further, FIG. 4 is a graph showing the temperature rise characteristics of a heat generating secondary battery in which an internal short circuit causes a thermal runaway and an adjacent secondary battery in an assembled battery with a small amount of heat conduction between the secondary batteries. In this assembled battery, adjacent secondary batteries are separated by 1 mm, and the heat of a secondary battery that is thermally runaway is not transferred by heat conduction, but is transferred to the adjacent secondary battery only by radiant heat. In this figure, the temperature rise of a secondary battery that is thermally runaway due to an internal short is indicated by a curve A, and the temperature rise of a secondary battery adjacent thereto is indicated by a curve B. In this assembled battery, since the heat transfer of the secondary battery that runs out of heat is small, the temperature after 30 seconds becomes extremely high at about 400 ° C. Furthermore, the heat of the high-temperature secondary battery is radiated heat to the adjacent secondary battery. The temperature of the adjacent secondary battery is rapidly increased after about 150 seconds, and the temperature rapidly increases. After 200 seconds, the temperature of the secondary battery is increased to over 500 ° C. . In this assembled battery, if one of the secondary batteries is thermally runaway, the neighboring secondary battery is also triggered by thermal runaway. Therefore, in the assembled battery containing a plurality of secondary batteries, the heat of one secondary battery is Runaway causes all secondary batteries to run away.

  FIG. 5 is a graph showing a temperature rise characteristic of a heat generating secondary battery in which an internal short circuit causes a thermal runaway and a secondary battery adjacent thereto in an assembled battery that controls heat conduction between the secondary batteries to a specific state. . In this assembled battery, a thermal runaway prevention wall having a thickness of 1 mm and a thermal conductivity of 0.2 W / m · K is provided between the secondary batteries, and the thermal runaway secondary battery that performs thermal runaway with the thermal runaway prevention wall. This heat is blocked from being transferred to the adjacent secondary battery by radiant heat, and a specific amount of heat is transferred to the adjacent secondary battery only by heat conduction with the thermal runaway prevention wall. In this figure, a temperature rise of a heat generating secondary battery that is thermally runaway due to an internal short circuit is shown by a curve A, and a temperature rise of the adjacent secondary battery is shown by a curve B. In this assembled battery, the heat of the exothermic secondary battery that is thermally runaway is transferred to the thermal runaway prevention wall due to heat conduction, so the temperature rise of the exothermic secondary battery that is thermally runaway becomes moderate and the temperature rises to 400 ° C. The time is extended to nearly 100 seconds, and an excellent feature that can reliably prevent thermal runaway of the adjacent secondary battery is realized. That is, even if one of the secondary batteries has a thermal runaway, the thermal runaway of the adjacent secondary battery is not induced. Therefore, even if any secondary battery runs out of heat, it is possible to end up with thermal runaway of only the secondary battery.

  As shown in FIG. 5, the assembled battery of FIG. 1 has a thermal runaway prevention wall 3 between adjacent secondary batteries 1 so that a heat runaway secondary battery that has caused thermal runaway does not induce thermal runaway of the adjacent secondary battery. Is provided. The thermal runaway prevention wall 3 is integrally formed with a plastic heat conduction cylinder 4 and constitutes a part of the heat conduction cylinder 4. The heat conduction cylinder 4 is formed so that the shape of the inner surface is equal to the outer shape of the secondary battery 1. Furthermore, the heat conduction tube 4 has a clearance of 0.5 mm or less between the inner surface of the heat conduction tube 4 and the outer surface of the secondary battery 1 so that the heat of the secondary battery 1 can be transferred to the thermal runaway prevention wall 3 by heat conduction. The surface of the secondary battery 1 is brought into contact with the inner surface of the thermal runaway prevention wall 3 in a surface contact state.

  Furthermore, in order to control the amount of heat conducted by the thermal runaway prevention wall 3, the thermal runaway prevention wall 3 is a plastic having a thermal conductivity of 0.05 W / m · K or more and 3 W / m · K or less. Molded with. The plastic forming the thermal runaway prevention wall 3 and the heat conducting cylinder 4 can be controlled by the type of plastic and the filler. The filler is excellent in heat conduction and filled with a powder, for example, a metal powder, so that the heat conductivity can be increased. If the thermal conductivity of the thermal runaway prevention wall is less than 0.05 W / m · K, the thermal conductivity of the thermal runaway prevention wall will be reduced, and the temperature rise of the exothermic rechargeable battery will be steep and the maximum temperature will also be Get higher. For this reason, the time during which the exothermic secondary battery runs out of heat is short, and the exothermic secondary battery that has become hot due to thermal runaway heats the adjacent secondary battery to induce thermal runaway. Conversely, if the thermal conductivity of the thermal runaway prevention wall is greater than 3 W / m · K, the amount of heat conducted from the thermal runaway secondary battery to the adjacent secondary battery is large, and the thermal runaway secondary battery Makes the next secondary battery run out of heat. The thermal runaway prevention wall 3 having a thermal conductivity of 0.05 W / m · K or more and 3 W / m · K or less is optimal in the amount of heat conducted from the heat generating secondary battery 1A that generates heat due to thermal runaway. The heat generation secondary battery 1A is dissipated by heat conduction to limit the temperature rise, and the amount of conduction heat to the adjacent secondary battery 1B is also limited, so that the adjacent secondary battery 1B can run out of heat. Effectively prevent.

  Furthermore, in addition to the thermal conductivity, the thermal runaway prevention wall 3 needs to have a thickness within a limited range of 0.5 mm or more and 3 mm or less. If the thermal runaway prevention wall between the secondary batteries is thinner than 0.5mm, the heat conduction from the exothermic secondary battery that causes thermal runaway to the adjacent secondary battery increases, and the exothermic secondary battery that causes thermal runaway is adjacent. The rechargeable battery is overheated and run out of heat. On the other hand, if the thermal runaway prevention wall is thicker than 3 mm, the heat conduction from the heat-generating secondary battery that runs out of heat to the adjacent secondary battery is too small, and the temperature of the heat-running secondary battery that runs out of heat becomes abnormally high. The heated secondary battery heats the adjacent secondary battery to induce thermal runaway.

  The assembled battery of the present invention controls the thermal runaway of the secondary battery by controlling the heat transfer within a very delicate range. Secondary batteries generate heat due to thermal runaway and are overheated, but secondary batteries do not generate heat indefinitely. The calorific value of the secondary battery is specified by the capacity of the secondary battery. Therefore, in a state where the secondary battery generates heat, the heat transfer is controlled to a specific state to prevent thermal runaway. When the secondary battery generates heat due to thermal runaway, the heat dissipation amount can be increased to reduce the temperature rise of the secondary battery. However, in this state, the heat dissipated overheats the adjacent secondary battery and induces thermal runaway. On the other hand, if the heat dissipation of a heat-generating secondary battery that causes thermal runaway is reduced, heat runaway of the adjacent secondary battery is not induced by heat dissipation, but the temperature of the heat-generating secondary battery that is not dissipated becomes abnormally high and overheated The secondary battery induces thermal runaway of the adjacent secondary battery. However, if the heat dissipation of a heat-generating secondary battery that runs out of heat is controlled to a specific heat amount, the adjacent secondary battery does not run out of heat due to heat dissipation from a heat-generating secondary battery that rises in temperature due to thermal runaway. The temperature rise of the exothermic secondary battery that is thermally runaway is limited by the amount of heat, and the maximum temperature is lowered. For this reason, the exothermic secondary battery that undergoes thermal runaway is not overheated, and the adjacent secondary battery does not run thermal runaway. Although the temperature of a heat generating secondary battery that runs out of heat increases with time due to generated heat, if the temperature rise is limited by controlling the amount of discharge, the amount of heat generation decreases and the temperature does not rise after a certain period of time. Therefore, by controlling the heat dissipation of the heat generating secondary battery that runs out of heat to a specific range, the heat generating secondary battery that runs out of heat limits the amount of heat that overheats the adjacent secondary battery, and also limits the maximum temperature, It can cleverly prevent thermal runaway of the adjacent secondary battery.

  Therefore, the assembled battery of FIG. 1 blocks the radiant heat of the heat generating secondary battery 1A by the thermal runaway prevention wall 3 provided between the secondary batteries 1, but the heat generated by the heat generating secondary battery 1A is adjacent to the heat generating secondary battery 1A. The secondary battery 1B is thermally conducted to dissipate the heat generating secondary battery 1A, thereby preventing the thermal runaway of the heat generating secondary battery 1A from being transmitted to the adjacent secondary battery 1B.

  The heat conducting cylinder 4 of FIG. 6 has an inner surface formed into a taper shape, and a portion protruding from the inner surface is brought into surface contact with the surface of the secondary battery 1. The heat conducting cylinder 4 can be brought into surface contact with the surface by inserting the secondary battery 1 having a somewhat outside diameter error. The heat conduction cylinder 4 has a minimum clearance of 0.5 mm or less between the inner surface and the secondary battery 1.

  The secondary battery 1 of the assembled battery is a lithium ion secondary battery. The lithium ion secondary battery 1 uses a non-aqueous electrolyte solution. If this electrolyte is ejected due to thermal runaway, a dangerous state is reached. For this reason, since it is important for the battery pack of a lithium ion secondary battery to effectively prevent thermal runaway, the battery pack of the present invention prevents thermal runaway with a unique configuration. Suitable for ion secondary battery.

  The heat conducting cylinder 4 is formed so as to cover the entire circumference of the secondary battery 1. However, as shown in FIG. 1, an opening 5 may be provided in a part of the heat conducting cylinder 4, and a temperature sensor 6 may be provided in the opening 5 to detect the temperature of the secondary battery 1.

  In the illustrated assembled battery, the secondary battery 1 is a cylindrical battery. Further, in the assembled battery of FIG. 1, another secondary battery 1 is arranged in the valley of the adjacent secondary batteries 1, and three batteries are arranged from the closest gap between the three secondary batteries 1. The boundary region surrounded by the secondary battery 1 is molded without gaps with the plastic that molds the thermal runaway prevention wall 3. This assembled battery can absorb the heat of the exothermic secondary battery 1A in which the plastic in the boundary region is thermally runaway, and can slow the temperature rise of the exothermic secondary battery 1A that is thermally runaway.

  By the way, in this specification, the thickness of the thermal runaway prevention wall 3 between the secondary batteries 1 means the thickness of the closest part in a cylindrical battery. This is because the heat transfer in this portion is the largest and affects the thermal runaway of the secondary battery 1.

  Furthermore, the thermal runaway prevention wall 3 can be provided with an opening 5 in a part between the secondary batteries 1. However, the opening 5 opens only to one of the opposing surfaces of the adjacent secondary battery 1 as shown in FIG. 7, or both of the opposing surfaces of the adjacent secondary battery 1 as shown in FIG. Can be provided. The heat conducting cylinders 4 having openings on both opposing surfaces of the adjacent secondary batteries 1 are provided in a portion where the distance (D) between the adjacent secondary batteries 1 is five times or more the minimum distance (d). Since the heat conduction due to radiant heat decreases in inverse proportion to the square of the distance, when the interval between the secondary batteries 1 is increased five times, the heat conduction due to the radiant heat becomes 1/25, which is almost negligible. Therefore, even if the heat conducting cylinder 4 has the opening 5 on the opposite surface of the portion of 5 times or more of the minimum interval, the amount of heat transferred from the opening 5 to the adjacent secondary battery 1B by radiant heat is small. For this reason, the thermal runaway of the adjacent secondary battery 1B is not induced due to the radiant heat of the opening 5.

  Further, the assembled battery shown in FIGS. 9 to 11 includes an inner case 8 in which end plates 7 are connected to both ends of the heat conducting cylinder 4, and a plurality of secondary batteries 1 are accommodated in the inner case 8. ing. The illustrated inner case 8 is divided into a pair of case units 8A by dividing the heat conducting cylinder 4 into two in the middle in the axial direction. The case unit 8A is molded of plastic into a shape formed by connecting an end plate 7 to the end of the divided heat conducting cylinder 4. In the inner case 8, the secondary battery 1 is inserted from an opening that is a divided end of the heat conducting cylinder 4, and a pair of case units 8 </ b> A are connected to each other so that a plurality of secondary batteries 1 are accommodated in the inner case 8. ing.

  Although not shown in the figure, the heat conduction cylinder 4 divided in the middle has an inner surface formed in a tapered shape in which the inner diameter gradually decreases from the divided end side toward the end plate side. In the heat conducting cylinder 4, a portion protruding from the inner surface of the end portion on the end plate 7 side is brought into surface contact with the surface of the secondary battery 1. The heat conducting cylinder 4 can be brought into surface contact with the surface by inserting the secondary battery 1 having a somewhat outside diameter error. This heat conducting cylinder 4 also has a minimum clearance of 0.5 mm or less between the inner surface and the secondary battery 1. As described above, the structure in which the heat conducting cylinder 4 is divided has a feature that simplifies the design of a mold for molding plastic and facilitates plastic molding.

  In the assembled battery shown in the figure, the heat conducting cylinder 4 is divided into two in the middle in the axial direction, but the heat conducting cylinder can also be divided into three or more. Although not shown, the inner case that divides the heat conducting cylinder into three or more parts is divided into end case units at both ends and an intermediate middle case unit, and these case units are connected to each other to form a plurality of two cases. The secondary battery is stored inside.

  The divided case units 8A are connected to each other by screwing screws (not shown) into bosses 9 formed integrally with plastic. However, the case units can be connected by a locking structure, or can be connected by bonding, or they can be connected in combination.

  Furthermore, the assembled battery is provided with a thermal runaway prevention wall 3 between the adjacent secondary batteries 1 as shown in FIG. The thermal runaway prevention wall 3 is integrally formed with the heat conduction cylinder 4 and constitutes a part of the heat conduction cylinder 4. The heat conduction cylinder 4 is formed so that the shape of the inner surface is equal to the outer shape of the secondary battery 1. The heat conduction tube 4 has a clearance of 0.5 mm or less between the inner surface of the heat conduction tube 4 and the outer surface of the secondary battery 1 so that the heat of the secondary battery 1 can be moved to the thermal runaway prevention wall 3 by heat conduction. The surface of the secondary battery 1 is brought into contact with the inner surface of the thermal runaway prevention wall 3 in a surface contact state. Furthermore, the thermal runaway prevention wall 3 is formed of a plastic having a thermal conductivity of 0.05 W / m · K or more and 3 W / m · K or less. In addition to the thermal conductivity, the thermal runaway prevention wall 3 has a thickness in a limited range of 0.5 mm or more and 3 mm or less. This assembled battery also cuts off the radiant heat of the heat generating secondary battery that generates heat by the thermal runaway prevention wall 3 provided between the secondary batteries 1, but the heat generated by the heat generating secondary battery is heated to the adjacent secondary battery. Conductive heat is dissipated from the heat generating secondary battery, and thermal runaway of the heat generating secondary battery is prevented from being transmitted to the adjacent secondary battery.

  Further, in the inner case 8 shown in FIGS. 9 and 10, an opening 5 is provided in a part of the heat conducting cylinder 4, and a temperature sensor 6 is provided in the opening 5. This assembled battery can detect the temperature of the secondary battery 1 with the temperature sensor 6. The illustrated inner case 8 is provided with an opening 5 by cutting away the connecting portions of the divided heat conducting cylinders 4 facing each other. In the assembled battery of FIG. 11, the temperature sensor 6 is disposed by providing openings 5 at two locations on the left and right.

  Further, the battery pack shown in the figure includes a circuit board 10 on which a circuit for controlling charge / discharge of the secondary battery 1 housed in the inner case 8 is mounted, a terminal board 12 having output terminals and connection terminals, and the circuit board 10. And a substrate holder 11 for arranging the terminal substrate 12 at a predetermined position. The circuit board 10 is connected to the secondary battery 1 via a lead, and the voltage detection circuit to be mounted detects the battery voltage of each secondary battery 1 and controls charging / discharging of these batteries. The terminal board 12 is equipped with an output terminal for output of the built-in secondary battery 1 and a connection terminal with an external device, and is arranged on the upper side of the circuit board 10. The board holder 11 is fixed to the upper surface of the inner case 8, and the circuit board 10 and the terminal board 12 are arranged in a predetermined position in a mutually parallel posture. The inner case to which the substrate holder is fixed is housed in an outer case (not shown) to form an assembled battery.

It is a schematic block diagram of the assembled battery concerning one Example of this invention. It is a conceptual diagram which shows the heat transfer of the assembled battery concerning one Example of this invention. It is a graph which shows the temperature rise characteristic of the exothermic secondary battery and the adjacent secondary battery in an assembled battery with much heat conduction between secondary batteries. It is a graph which shows the temperature rise characteristic of the exothermic secondary battery and the adjacent secondary battery in an assembled battery with little heat conduction between secondary batteries. It is a graph which shows the temperature rise characteristic of the exothermic secondary battery and the adjacent secondary battery in the assembled battery which controls the heat conduction between secondary batteries to a specific state. It is a longitudinal cross-sectional view of the heat conductive cylinder of the assembled battery concerning one Example of this invention. It is a principal part expanded sectional view of the assembled battery concerning the other Example of this invention. It is a principal part expanded sectional view of the assembled battery concerning the other Example of this invention. It is a perspective view of the assembled battery concerning the other Example of this invention. It is the perspective view which turned the assembled battery shown in FIG. 9 upside down. FIG. 10 is a vertical sectional view of the assembled battery shown in FIG. 9.

Explanation of symbols

1 ... secondary battery 1A ... exothermic secondary battery
DESCRIPTION OF SYMBOLS 1B ... Secondary battery 2 ... Case 3 ... Thermal runaway prevention wall 4 ... Thermal conduction cylinder 5 ... Opening part 6 ... Temperature sensor 7 ... End plate 8 ... Inner case 8A ... Case unit 9 ... Boss 10 ... Circuit board 11 ... Board holder 12 ... Terminal board

Claims (7)

In an assembled battery in which a plurality of secondary batteries (1) are accommodated in a case (2) adjacent in parallel orientation
A plastic thermal runaway prevention wall (3) is provided between adjacent secondary batteries (1), and this thermal runaway prevention wall (3) has an inner surface shape equal to the outer shape of the secondary battery (1). It is molded integrally with the heat conduction cylinder (4) molded into a shape, and the thermal runaway prevention wall (3) is part of the heat conduction cylinder (4).
The heat conduction cylinder (4) has a clearance of 0.5 mm or less between its inner surface and the outer surface of the secondary battery (1), and the surface of the secondary battery (1) is in surface contact with the inner surface of the thermal runaway prevention wall (3). In contact with the state,
Furthermore, the plastic forming the thermal runaway prevention wall (3) has a thermal conductivity of 0.05 W / m · K or more and 3 W / m · K or less, and the thermal runaway prevention wall (3) is thick. The thickness is 0.5 mm or more and 3 mm or less,
The thermal runaway prevention wall (3) provided between the secondary batteries (1) blocks the radiant heat of the secondary battery (1) that generates heat, but the secondary battery (1) generates heat from the adjacent secondary battery (1). Conducting heat to the battery (1) to dissipate the heat generated from the secondary battery (1), thereby preventing the thermal runaway of the secondary battery (1) from being transmitted to the adjacent secondary battery (1). Assembled battery.   The assembled battery according to claim 1, wherein the heat conducting cylinder (4) is divided into a plurality of parts in the middle in the axial direction.   An inner case (8) is formed by connecting end plates (7) to both ends of the heat conduction cylinder (4). This inner case (8) has two heat conduction cylinders (4) in the middle of the axial direction. It is divided into a pair of case units (8A), and the pair of divided case units (8A) are connected to each other to store a plurality of secondary batteries (1) in the inner case (8). The assembled battery according to claim 1.   The assembled battery according to any one of claims 1 to 3, wherein the inner surface of the heat conducting cylinder (4) is formed into a tapered shape, and a portion protruding from the inner surface is brought into surface contact with the surface of the secondary battery (1). .   The assembled battery according to any one of claims 1 to 3, wherein the secondary battery (1) is a lithium ion secondary battery.   An opening (5) is provided in a part of the heat conduction cylinder (4), and a temperature sensor (6) is provided in the opening (5) to detect the temperature of the secondary battery (1). The assembled battery according to any one of claims 1 to 3. The secondary battery (1) is a cylindrical battery, and another secondary battery (1) is arranged in the valley of the adjacent secondary battery (1), and three secondary batteries (1 4) The boundary region surrounded by the three secondary batteries (1) from the closest approach gap is formed with plastic forming the thermal runaway prevention wall (3) without any gap. Assembled battery.

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