JP5309696B2 - Assembled battery - Google Patents

Description

  The present invention relates to an assembled battery comprising a large number of single cells.

  In recent years, global warming due to carbon dioxide and other harmful substances has become a major problem, and electric vehicles (EV) and hybrid electric vehicles (HEV) have been rapidly developed as alternatives to gasoline vehicles. As power sources for EVs and HEVs, the use of secondary batteries, polymer electrolyte fuel cells, and the like has been studied, and secondary batteries are considered promising among them.

  In the case of a single battery, the discharge voltage of a commercially available secondary battery is about 1.1 V for a nickel-hydrogen storage battery, about 1.2 V for a nickel-cadmium storage battery, about 2.0 V for a lead storage battery, a lithium ion battery or a polymer In a nonaqueous electrolyte battery such as an electrolyte battery, the voltage is about 2.0 to 4.0 V.

  On the other hand, a high voltage of 100 V or higher is necessary for a power source for driving an EV or HEV motor. Therefore, when a secondary battery is used as a power source for EVs or HEVs, it is necessary to increase the voltage by using an assembled battery in which a large number of single cells are connected in series. Depending on the capacity of the unit cells, a plurality of unit cells may be connected in parallel and connected in series, which may be used in a mixed state of series and parallel.

  Such an assembled battery can be used not only for EVs and HEVs, but also for any power source that requires a high voltage, and can be set to a desired voltage by changing the number of cells connected in series. Can do.

  Patent Document 1 discloses that, in an assembled battery using a nonaqueous electrolyte secondary battery, a connection member is attached to a bolt portion of a terminal of each battery and is tightened with a nut or the like to connect each battery. Has been.

  Further, in Patent Document 2, in a battery pack using a lithium secondary battery, a connection body is used for connection between single cells, and the positive terminal of one single battery is inserted into one electrode terminal insertion hole of the connection body. And the technique of fixing with a connection body attachment nut in the state which inserted the negative electrode terminal of the other unit cell in the other electrode terminal insertion hole is disclosed.

Further, in Patent Document 3, in an assembled battery using a lithium secondary battery, a plurality of unit cells are connected by connecting external terminals provided on a unit cell such as a screw type to form a unit. Is disclosed in which a unit connection jig and a nut are connected in series.
JP 2004-200024 A JP 2000-138045 A JP 2000-090967 A

  As for the conventional assembled battery, as described in Patent Documents 1 to 3, a connection body and a nut or the like are used for the connection between the individual batteries, and after the assembled battery is assembled, It was held in a connected state, and the connection between each cell could not be easily removed.

  However, generally, a protection circuit and various control circuits are connected to the assembled battery. In particular, when a non-aqueous electrolyte secondary battery is used as a unit cell, the non-aqueous electrolyte secondary battery has a high voltage and a flammable organic solvent is used in the electrolyte. A protection circuit is essential. These protection circuits are particularly important when the capacity of the unit cell is 3 Ah or more.

  If the battery is stored with each cell connected, a high voltage is always applied between the external terminals of the battery, and if an external short circuit occurs for some reason, a large current flows, which is dangerous. However, there was a problem that the assembled battery was damaged and could not be used.

  In addition, in a battery pack in which each unit cell is connected, if a protection circuit or the like is connected, even when the battery is not used, dark current flows, the battery is discharged little by little, and the capacity decreases. However, there was a problem that the voltage also decreased.

  Therefore, an object of the present invention is to prevent a short circuit between terminals and prevent dark current from flowing during storage of an assembled battery, thereby suppressing a decrease in battery capacity and a decrease in battery voltage during storage. Is to provide a simple assembled battery.

The invention of claim 1 comprises a large number of single cells each having a first connection portion at a terminal, a second connection portion connectable to the first connection portion, and a connection member connected to the second connection portion. in the assembled battery, the second connecting portion includes a rotary shaft, one end of the two other end different from the end which is connected to the connecting member is connected to the first connecting portion of different said unit cells each, A movable connecting portion that rotates about the rotation axis is provided, and when the assembled battery is used, all the single cells are connected in series, in parallel, or in a mixed state of the series and parallel, and are connected by the connection member. When not in use, all the cells are disconnected from the connecting member by rotating the movable connecting portion by moving the connecting member and disconnecting the other end of the movable connecting portion from the first connecting portion. Features.

The invention of claim 2 is characterized in that, in the assembled battery, the connecting member is capable of simultaneously connecting at least three unit cells.
According to a third aspect of the present invention, in the assembled battery, one end of the movable connection portion is connected to the connection member via a spring.

  In the assembled battery according to claim 1 of the present invention, all the single cells are connected in series, parallel, or a mixture of series and parallel when in use, but all the single cells are disconnected from the connecting member when not in use. The terminals of each cell are not connected anywhere. For this reason, there is no danger of short-circuiting terminals when no assembled battery is used, and no dark current flows.Therefore, the causes of battery capacity reduction and voltage drop are limited to those caused by battery self-discharge. It is possible to suppress the battery capacity decrease and voltage decrease observed in the battery.

  Further, in the assembled battery of claim 2, by using a connecting member capable of simultaneously connecting at least three or more unit cells, a large number of unit cells can be connected or separated simultaneously in a short time. The working time can be greatly shortened.

  The present invention provides an assembled battery comprising a large number of single cells each having a first connection portion at a terminal and a connection member having a second connection portion connectable to the first connection portion. The single cells are connected in series, in parallel or in a state in which series and parallel are mixed, and are connected by the connecting member, and all the single cells and the connecting member are disconnected when the assembled battery is not used. It is what.

  Moreover, the present invention is characterized in that, in the above assembled battery, the connection member can connect at least three unit cells at the same time.

  1st embodiment of this invention connects between each cell of an assembled battery by an insertion system. 1st Embodiment of this invention is described based on FIGS. FIG. 1 is an external perspective view of a unit cell. In FIG. 1, 1 is a non-aqueous electrolyte secondary battery, 2 is a battery container, 3 is a battery case, 4 is a battery lid, 5 is a positive terminal, 6 is a negative terminal, 7 is an insulator, 8 is an electrolyte injection port, and 9 is a safety valve.

  A non-aqueous electrolyte secondary battery was used as the unit cell shown in FIG. In the nonaqueous electrolyte secondary battery 1, a wound type power generation element (not shown) is accommodated in a battery container 2 formed in a long cylindrical shape by, for example, metal.

  The battery container 2 includes a metal battery case 3 formed in a bottomed long cylindrical container shape, and a metal battery cover 4 formed in a substantially long disk shape and sealing the opening of the battery case 3. It consists of A power generation element is accommodated in the battery case 3. The opening of the battery case 3 is sealed by welding the battery lid 4.

  A positive electrode terminal 5 and a negative electrode terminal 6 made of a conductive material are passed through and fixed to the battery lid 4. These terminals 5 and 6 are inserted into two through holes provided in the battery lid 4, and are supported in an insulated state by the ceramic insulator 7 with respect to the battery lid 4. The battery lid 4 is provided with an electrolyte injection port 8 and a safety valve 9. The electrolyte solution injection port 8 is sealed after the battery is assembled and the electrolyte solution is injected. The safety valve is formed by covering a through-hole provided in the battery lid 4 with a metal thin film.

  FIG. 2 is an enlarged view of the positive electrode terminal 5 and the negative electrode terminal 6 of the unit cell, and the shape of the terminal is composed of a cylindrical part 11 connected from the inside of the battery to the outside of the battery, and a connection part 12 provided on the upper part. Has been. The connection part 12 consists of a pair of metal plate with the upper end part opened. As a material of the connection part 12, a conductive metal is used. In addition, the material of the connection part 12 may be the same as the material of the cylindrical part 11, and may differ.

  FIG. 3 shows the connecting member. The connecting member is obtained by attaching a necessary number of U-shaped protrusions 14 to a support plate 13 made of an insulating material with, for example, screws 15. Here, an example in which three U-shaped protrusions 14 are attached is shown.

  FIG. 4 is a diagram showing a state where a connecting member is connected to a single cell to form an assembled battery. In FIG. 4, 10 is a cell, 13 is a support plate, 14 is a letter-shaped protrusion, 16 is a connection member, 17 is a battery pack positive terminal, and 18 is a battery pack negative terminal. FIG. 4 shows an example in which four unit cells are connected in series to form an assembled battery. In the assembled battery shown in FIG. 4, each unit cell 10 is arranged so that the positive electrode terminal is on the left side and the negative electrode terminal is on the right side. 1 is connected to the device via the assembled battery positive terminal 17, and the rightmost unit cell No. 1 is connected. The negative electrode terminal 4 is connected to the device via the assembled battery negative electrode terminal 18. The unit cell No. 1 positive electrode terminal and assembled battery positive electrode terminal 17, and unit cell No. 1 It is assumed that the negative electrode terminal 4 and the assembled battery negative electrode terminal 18 are always connected both when used and when not used.

  When the assembled battery is used, as shown in FIG. 4, the connecting member 16 is connected to the unit cell 10 to connect the four unit cells in series, and when the assembled battery is not used, The connection member 16 is disconnected, and the electrical connection between the single cells is disconnected. In this way, by using the connection member, connection and disconnection between a large number (here, four) of single cells can be performed in a short time with a simple operation.

  2nd embodiment of this invention connects between each cell of an assembled battery by a switch system. A second embodiment of the present invention will be described based on FIG. 5, FIG. 6, and FIG. Also in the second embodiment, the same nonaqueous electrolyte secondary battery as that used in the first embodiment shown in FIG. FIG. 5 shows an enlarged view of the positive electrode terminal 5 and the negative electrode terminal 6 of the unit cell of the second embodiment, and the shape of the terminal is a cylindrical portion 21 connected from the inside of the battery to the outside of the battery, and a plate provided on the upper portion thereof. The connection part 22 of a shape is comprised. A conductive metal is used as the material of the connecting portion 22. In addition, the material of the connection part 22 may be the same as the material of the cylindrical part 21, and may differ.

  FIG. 6 is a diagram showing a state in which a connection member is connected to a single cell by a switch method to form an assembled battery, and FIG. 7 is a diagram showing a state in which the connection between the single cells is disconnected. 6 and 7, 10 is a single cell, 5 is a positive electrode terminal of the single cell, 6 is a negative electrode terminal of the single cell, 17 is an assembled battery positive electrode terminal, 18 is an assembled battery negative electrode terminal, and 23 is a switch-type connection member. Reference numeral 24 denotes a movable connecting portion, 25 denotes a rotating shaft of the movable connecting portion, and 26 denotes a spring.

  FIG. 6 shows an example in which four unit cells are connected in series to form an assembled battery. In the assembled battery shown in FIG. 6, each cell 10 is arranged so that the positive electrode terminal is on the left side and the negative electrode terminal is on the right side. 1 is connected to the device via the assembled battery positive terminal 17, and the rightmost unit cell No. 1 is connected. The negative electrode terminal 4 is connected to the device via the assembled battery negative electrode terminal 18. The unit cell No. 1 positive electrode terminal and assembled battery positive electrode terminal 17, and unit cell No. 1 It is assumed that the negative electrode terminal 4 and the assembled battery negative electrode terminal 18 are always connected both when used and when not used.

  Then, when using the assembled battery, as shown in FIG. 6, the position of the connecting member 23 is adjusted so that the positive electrode terminal 5 and the negative electrode terminal 6 of the adjacent unit cell are connected by the movable connecting portion 24. Four unit cells are connected in series. On the other hand, when the assembled battery is not used, as shown in FIG. 7, the connection member 23 is moved leftward from the position of FIG. 6 to the position of FIG. 7, and the movable connection portion 24 is disconnected from each unit cell 10. Disconnect the electrical connection between the cells.

  As described above, also in the second embodiment, by using a switch-type connection member, connection (and disconnection) between a large number (in this case, four cells) of single cells can be performed in a short time with a simple operation. Is.

  In addition, the shape of the electrode terminal and connection member of a cell is not limited to the shape illustrated to 1st embodiment or 2nd embodiment, The shape which can perform the electrical connection and disconnection between cells easily. Any shape can be used.

  Moreover, the unit cell used for the assembled battery of this invention is not limited to a nonaqueous electrolyte secondary battery, It is possible to use all batteries, such as a lead storage battery and a nickel-hydrogen battery. Furthermore, the shape of the unit cell is not limited to the long cylindrical type, and can be used for an assembled battery using batteries of any shape such as a cylindrical type or a rectangular type.

[Examples 1 and 2 and Comparative Example 1]
[Example 1]
(1) Production of Positive Electrode Plate As a positive electrode active material, a mixture of spinel type lithium manganese oxide (LiMn ₂ O ₄ ) and lithium cobaltate (LiCoO ₂ ) at a weight ratio of 1: 1 was used. This positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, and acetylene black (AB) as a conductive agent are mixed at a weight ratio of 94: 4: 2, and N-methyl-2-pyrrolidone ( NMP) was added to prepare a positive electrode mixture paste. This paste was uniformly applied on both sides of a current collector made of an aluminum foil having a thickness of 20 μm, dried, pressed and then cut to prepare a strip-like positive electrode plate.

(2) Production of negative electrode plate Carbon as an active material and PVdF as a binder were mixed at a blending ratio of 90:10, and NMP was added to prepare a negative electrode mixture paste. This paste was uniformly applied to both surfaces of a current collector made of a copper foil having a thickness of 16 μm, and a strip-shaped negative electrode plate was produced by the same method as that for the positive electrode plate.

(3) Preparation of electrolyte solution 1 mol / L lithium hexafluorophosphate in a mixed solvent in which ethylene carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (MEC) were mixed at a ratio of 2: 1: 2 A non-aqueous electrolyte solution in which (LiPF ₆ ) was dissolved was prepared.

(4) Manufacture of unit cell A laminate of the positive electrode plate, the separator, the negative electrode plate, and the separator in that order was wound to prepare a long cylindrical power generation element. The separator used was a laminate of microporous polyethylene having a thickness of 15 μm and microporous polypropylene having a thickness of 10 μm.

  This long cylindrical power generation element was housed in an aluminum battery case. Next, the positive electrode and the negative electrode of the power generation element were connected to the positive electrode terminal and the negative electrode terminal attached to the battery lid via the positive electrode lead and the negative electrode lead. Thereafter, the battery lid was attached to the battery case by laser welding. Finally, the electrolyte solution was injected from the injection port opened in the sealing plate, and then this injection port was closed with a laser welding sealant.

  In the battery of Example 1, the shapes of the positive electrode terminal and the negative electrode terminal were the same as those in the first embodiment shown in FIG.

The appearance of the obtained battery is the same as that shown in FIG. 1, the design capacity of this battery is 4.0 Ah, and the size of the battery is 65 mm wide, 11.3 mm thick, and high. The thickness was 115 mm.
(5) Production of assembled battery Four obtained unit cells were arranged so that the positive electrode terminal and the negative electrode terminal were adjacent to each other, and fixed at the bottom of the battery to obtain assembled battery A of Example 1. In addition, the space | interval of 5 mm was provided between adjacent batteries so that the air for cooling might flow between batteries.

  Then, prepare an insertion-type connection member having the same shape as shown in FIG. 3, and immediately before using the assembled battery, insert the insertion-type connection member into the terminal of the assembled battery as shown in FIG. Four unit cells were connected in series. In addition, when the assembled battery is not used, the plug-in connection member is removed so that each single cell is in an open state.

[Example 2]
A battery pack B of Example 2 was obtained in the same manner as in Example 1 except that the shape of the positive electrode terminal and the negative electrode terminal of the unit cell was the same as in the second embodiment shown in FIG. Then, the cells were connected and disconnected in the same manner as in Example 1 using a switch-type connection member having the same shape as shown in FIGS.

[Comparative Example 1]
Except that the same four cells used in Example 1 were connected between the adjacent positive and negative terminals with a conductor, and the connection was fastened with a nut and fixed so that it could not be easily cut. Is the assembled battery C of Comparative Example 1 in the same manner as in Example 1.

[Short-circuit test]
Regarding the assembled batteries A, B and C of Example 1, Example 2 and Comparative Example 1, the positive and negative terminals of the assembled battery were intentionally short-circuited by connecting them with a copper wire having a diameter of 6 mm. The condition was observed. The results are summarized in Table 1.

  From the result of Table 1, in the battery C of the comparative example 1, since each single battery which comprises an assembled battery was connected in series, the phenomenon in which a terminal part melt | dissolved by the short circuit was seen. In addition, even in the battery A of Example 1 and the battery B of Example 2, when the single cells are connected in series with the connecting member, the phenomenon that the terminal portion melts due to a short circuit is observed as in Comparative Example 1. It was.

  On the other hand, in the case of the battery A of Example 1 and the battery B of Example 2, when the connecting member is removed and each unit cell is opened, the short circuit of the battery does not occur. There wasn't. As described above, it was found that the assembled battery can be prevented from being damaged when a short circuit occurs between the terminals by removing the connecting member when the battery is not used.

[Preservation test]
For the assembled batteries A, B and C of Example 1, Example 2 and Comparative Example 1, a battery charged at a constant current of 4A up to 4.2V and further at a constant voltage of 4.2V for a total of 3 hours was maintained at a constant temperature of 25 ° C. It stored for 30 days in the tank, measured the voltage of the assembled battery before and after storage, and calculated | required voltage drop. The results are summarized in Table 2.

  From the results in Table 2, the voltage drop when the single cells constituting the assembled battery are connected in series is 10 mV or more, whereas the battery A of Example 1 and the battery B of Example 2 are connected. When the member was removed and stored, the voltage drop was about 2 mV, which was found to be very small.

  In this way, in the assembled battery in a state where each unit cell is connected, dark current flows through the connected protection circuit and the like, the capacity of the battery is reduced, and the voltage is also reduced. It was found that by removing the connecting member when the battery is not used, the battery capacity and voltage can be suppressed.

  In the above embodiment, the case where four unit cells are connected in series has been described. However, the number of unit cells can be selected according to the application, and the connection between the unit cells is connected in series. The connection according to the application can be selected, such as parallel or a combination of series and parallel.

  Further, the number of connection members is not limited to one for the assembled battery, and the number of connection members may be increased so that connection and disconnection can be easily performed. For example, in the case of an assembled battery composed of 100 single cells, two connecting members may be connected and disconnected by 50 single cells, or four connecting members may be connected to each single cell 25. It is also possible to connect and disconnect one by one.

The external appearance perspective view of a cell. The enlarged view of the terminal part of the insertion-type cell. The figure which shows the connection member of an insertion system. The figure which shows the state which connected the connection member to the assembled battery. The enlarged view of the terminal part of a switch type cell. The figure which shows the state which connected the connection member to the cell by the switch system, and was made into the assembled battery. The figure which shows the state which cut | disconnected the connection between single cells.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte secondary battery 2 Battery container 5 Positive electrode terminal 6 Negative electrode terminal 10 Single cell 11 Cylindrical part of a battery terminal 12 Connection part provided in the upper part of a battery terminal 13 Support plate 14 U-shaped protrusion 16, 23 Connection member 17 assembled battery positive terminal 18 assembled battery negative terminal 24 movable connection part

Claims (3)

In an assembled battery comprising a large number of single cells each having a first connection portion at a terminal, a second connection portion connectable to the first connection portion, and a connection member connected to the second connection portion
The second connecting portion includes a rotating shaft and the rotating shaft, one end of which is connected to the connecting member and two other ends different from the one end are connected to the first connecting portion of the unit cell. With a movable connection that rotates around the center,
When using an assembled battery, all the cells are connected in series, in parallel, or connected in a state in which series and parallel are mixed, and when the assembled battery is not used, the movable connecting portion is moved by moving the connecting member. All the unit cells and the connection member are separated by rotating and separating the other end of the movable connection part from the first connection part.   The assembled battery according to claim 1, wherein the connecting member can connect at least three unit cells at the same time.   The assembled battery according to claim 1, wherein one end of the movable connection portion is connected to the connection member via a spring.