JP5249605B2 - Lithium secondary battery and battery pack - Google Patents

Description

  The present invention relates to a lithium secondary battery and an assembled battery using the same.

In a lithium secondary battery, an electrolyte injected into the inside generates an extremely small amount of decomposition gas at the initial stage of battery injection and during battery operation. As this cracked gas accumulates, the internal pressure of the battery container gradually rises. For example, if left for several years, the internal pressure may exceed the allowable pressure of the battery container, and the battery container may be destroyed. there were. This is an important problem particularly for a relatively large lithium secondary battery that requires a long life.
In addition, regardless of the size of the lithium secondary battery, the internal pressure of the battery container may increase due to abnormalities inside the battery.
For example, a gas vent valve (gas release valve) shown in Patent Document 1 is provided as a means for suppressing the increase in the internal pressure of the battery container within a range that does not exceed the allowable pressure of the battery container.

The gas vent valve covers an opening of a battery container, for example, a battery lid, with an elastic member and seals it. When the internal pressure exceeds a predetermined value, the elastic member is deformed by the pressure, so that the opening is opened and the gas accumulated inside is released to the outside. Thereby, the internal pressure can be suppressed to a predetermined value or less.
This gas vent valve is often mounted using a hole for injecting an electrolyte into the battery. For example, as shown in Patent Document 1, it is provided at a substantially central position of the battery lid. Yes.
Since the battery is usually used with the battery cover on the upper surface, the battery cover does not directly contact the electrolyte. Therefore, since the gas vent valve does not come into contact with the electrolytic solution, the function of the gas vent valve is not hindered.

Japanese Patent Laid-Open No. 2001-210379

By the way, in recent years, the use of a relatively large lithium secondary battery having a long life has spread, and it has been demanded to arrange it efficiently in a limited space. For this reason, for example, the battery lid may be located on the side surface from the viewpoint of installation space or ease of use, i.e., the battery may be placed sideways.
When installed in this way, when the gas vent valve is provided at a substantially central position of the battery lid, the position of the gas vent valve is lower than the liquid level of the electrolyte in the battery. Therefore, since the gas vent valve is immersed in the electrolytic solution, the original gas vent function may not be performed.
Further, when the internal pressure becomes high, the electrolyte solution may ooze out from the gas vent valve, so that the outside of the battery lid is contaminated and the battery performance is deteriorated.

  In view of the above problems, an object of the present invention is to provide a lithium secondary battery and an assembled battery that can effectively maintain the function of the gas vent valve regardless of the installation posture of the battery container.

In order to solve the above problems, the present invention employs the following means.
A lithium secondary battery according to the present invention includes a battery case having a box structure in which a positive electrode, a negative electrode, and a non-aqueous electrolyte are accommodated, a positive electrode terminal that constitutes one surface of the battery container, and is connected to the positive electrode. A battery lid that is attached so that a negative electrode terminal connected to the negative electrode protrudes, at a position close to each of the opposing sides of the battery lid, and When one of these sides is positioned above the other, the battery lid is passed through at least one location corresponding to these sides at a position above the liquid level of the non-aqueous electrolyte. A plurality of mounting holes provided, and a gas that is selectively mounted in the mounting hole located above the liquid level of the non-aqueous electrolyte among the plurality of mounting holes and seals the opening with an elastic member and the vent valve, wherein the plurality of instrumentation Of the hole, and the bolt to seal the said mounting hole wherein is screwed in the mounting hole locations immersed in the nonaqueous electrolytic solution, characterized in that is provided.

  According to the present invention, at least one mounting hole is provided corresponding to each side in the vicinity of the opposite sides of the battery lid, that is, a plurality of mounting holes are provided. It is possible to select the position where the is mounted. That is, the degassing valve can be installed by selecting a mounting hole located at an appropriate position. For example, when the battery cover is installed so as to be positioned on the upper surface, the battery cover does not come into direct contact with the nonaqueous electrolyte solution. For example, a gas vent valve may be attached to all the mounting holes. Good.

Also, the mounting holes provided in close proximity to the opposing sides are provided at positions that are above the level of the non-aqueous electrolyte when one of these sides is positioned above the other. Therefore, even if the lithium secondary battery is arranged so that the battery lid is located on the side surface, the mounting hole close to one of the sides is provided as long as the opposing sides are positioned vertically. Is positioned above the liquid level of the non-aqueous electrolyte. Therefore, if a degassing valve is mounted in the mounting hole located above, the degassing valve does not come into contact with the non-aqueous electrolyte, so that the original degassing function can be achieved. In this case, the remaining mounting holes are completely sealed.
Thus, even if the battery container is arranged so that the battery lid faces the upper surface or the side surface, the gas vent valve can be attached so as to perform an effective function.

Note that the “opposite sides” in the present invention mean the bordered edges of the battery lid, that is, the sides facing each other. Depending on the shape of the battery lid, this side may be a straight line, a curved line, even if they are parallel to each other, or the extended part or a relationship that intersects directly, Also good.
Regardless of which side of the battery cover is facing up, if the gas vent valve is installed in a mounting hole provided close to the side located on the upper side, the gas vent valve is at the level of the non-aqueous electrolyte. Since the degassing valve functions effectively by being positioned above, for example, when the battery container having a battery lid having a substantially rectangular shape (even-angled shape), the opposite sides are parallel, When the lithium secondary batteries are arranged in the vertical direction with the battery lid as the side surface on the same side, one can be turned upside down with respect to the other. Thereby, since it can arrange so that the other negative electrode terminal may be located on one positive electrode terminal, the distance between both terminals can be shortened. Therefore, the length of the bus bar connecting the two terminals can be shortened. The same applies to the case where the battery lids are arranged on the upper surface.

In the lithium secondary battery, the mounting hole may be provided in a corner formed by adjacent sides.
In the lithium secondary battery, the mounting hole may be provided in the opposite corner.

In this way, the gas vent valve can be mounted so as to perform an effective function even if the battery cover is arranged so that all of the adjacent sides are located above.
For example, when the battery cover is substantially rectangular, if the mounting holes are provided at the opposite corners, the vent valve can function effectively regardless of which of the four sides comes up. Can be installed.

  In consideration of wearability, the elastic member may be an O-ring.

  Moreover, you may comprise an assembled battery by connecting the said lithium secondary battery in multiple numbers in series or in parallel.

In this way, regardless of whether the battery cover is located on the top surface or on the side surface, lithium secondary batteries to which a gas vent valve can be attached are connected in series or in parallel so as to perform an effective gas venting function. An assembled battery having a simple shape can be configured.
Accordingly, various types of assembled batteries can be provided according to the space shape of the installation location or according to ease of use.

  According to the present invention, a position close to each of the opposing sides of the battery lid, and a position that is above the liquid level of the nonaqueous electrolyte when one of these sides is located above the other In addition, since the mounting holes for mounting the gas vent valves are provided in correspondence with these sides, the gas vent valve can be used even if the battery container is arranged so that the battery lid faces the upper surface or the side surface. Can be installed to perform effective functions.

Hereinafter, a lithium secondary battery 1 according to an embodiment of the present invention will be described with reference to the drawings.
[One Embodiment of Lithium Secondary Battery]
1 and 2 show a schematic configuration of an embodiment of a lithium secondary battery 1, in which FIG. 1 is a plan view and FIG. 2 is a front view. FIG. 3 is a schematic diagram schematically showing the internal configuration of the lithium secondary battery 1.

As shown in FIG. 3, the lithium secondary battery 1 includes a battery container 3, a nonaqueous electrolytic solution 5 containing lithium ions injected into the battery container 3, a positive electrode 7, a negative electrode 9, and a positive electrode A terminal 11 and a negative electrode terminal 13 are provided.
The battery container 3 has a hollow, substantially rectangular parallelepiped shape, and is formed of, for example, a steel material such as stainless steel, an aluminum material, or the like. In addition, the inner surface of the battery container 3 may be in direct contact with the nonaqueous electrolytic solution, but it is also possible to use one that is covered with an insulator such as a modified polyolefin.

The battery container 3 is formed in a shape with one surface (upper surface) opened. For example, after the positive electrode 7 and the negative electrode 9 are stored inside, the battery cover 15 is fixed and attached so as to cover the one surface. The
The battery lid 15 is a substantially rectangular plate-like body, and the periphery is composed of opposed long side portions (sides) LE1 and LE2 and opposed short side portions (sides) SE1 and SE2.
The long side portion LE1 and the long side portion LE2 are substantially parallel to each other. Further, the short side portion SE1 and the short side portion SE2 are substantially parallel to each other. The long side portions LE1 and LE2 and the short side portions SE1 and SE2 are substantially orthogonal to each other.

The positive electrode terminal 11, the safety valve 29, and the negative electrode terminal 13 are provided at a predetermined interval from the short side portion SE1 side at a position connecting the intermediate positions of the short side portions SE1 and SE2 of the battery lid 15.
A gas vent valve mounting hole (mounting hole) is formed in the corner portion constituted by the long side portion LE1 and the short side portion SE1 and the corner portion constituted by the long side portion LE2 and the short side portion SE2, respectively. 23 is provided so as to penetrate the battery lid 15. These corners are located on the diagonal line of the battery lid 15 and constitute opposing corners of the present invention.

The gas vent valve mounting hole 23 formed in the corner portion constituted by the long side portion LE1 and the short side portion SE1 is in a state where the battery lid 15 is located on the side surface, that is, the battery container 3 is laid down. In addition, when either the long side portion LE1 or the short side portion SE1 is located above, it is provided at a position above the position (liquid level) of the liquid surface of the nonaqueous electrolytic solution 5 injected therein. It has been.
Further, the gas vent valve mounting hole 23 formed in the corner portion constituted by the long side portion LE2 and the short side portion SE2 has the battery lid 15 located on the side surface, that is, the state in which the battery container 3 is laid down. And when either the long side portion LE2 or the short side portion SE2 is positioned above, the position is higher than the position (liquid level) of the liquid surface of the nonaqueous electrolyte 5 injected therein Is provided.

The positive electrode 7 is configured, for example, by applying lithium manganate (LiMn ₂ O ₄ ) capable of occluding and releasing lithium ions as a positive electrode active material on the surface of a main body made of aluminum foil or the like.
The negative electrode 9 is formed of, for example, carbon or graphite.
A plurality of the positive electrodes 7 and the negative electrodes 9 are alternately arranged, and a separator formed of, for example, a porous polymer material film such as polyethylene or polypropylene, a glass fiber, or a nonwoven fabric made of various polymer fibers is interposed between them. Is inserted.

The positive electrode terminal 11 is attached to the battery lid 15 via an insulator 25. The positive terminal 11 is made of aluminum, for example, and the inner end is connected to the positive electrode 7. For example, nickel plating may be applied to the surface of the outer end portion of the positive electrode terminal 11 in order to reduce the contact resistance.
A negative electrode terminal 13 is attached to the battery lid 15 via an insulator 25. The negative electrode terminal 13 is made of copper, for example, and the inner end is connected to the negative electrode 9.

A safety valve 29 is mounted at the center position of the battery lid 15. The safety valve 29 has a thin disk shape and is attached to the center of the battery lid 15. The safety valve 29 is formed of, for example, a metal material such as aluminum. For example, when an internal short circuit occurs in the lithium secondary battery 1 and the internal pressure rapidly increases, the safety valve 29 is ruptured and opened. Thereby, since an internal pressure falls, the situation where the whole battery container 3 bursts can be prevented.
Note that the structure and materials of the lithium secondary battery are examples, and various known structures and materials can be used.

Next, the gas vent valve 31 mounted in the gas vent valve mounting hole 23 will be described with reference to FIGS. FIG. 4 is a cross-sectional view showing a state where the gas vent valve 31 is mounted. FIG. 5 is a longitudinal sectional view of the gas vent valve 31. 6 is an X view of FIG.
The gas vent valve 31 includes a substantially cylindrical main body 33, a sealing O-ring (elastic member: O-ring) 35, and a sealed O-ring 37.
A protrusion 39 having a substantially regular hexagonal outer periphery is formed at a substantially intermediate position in the axial direction of the main body 33. On one end side of the main body 33, a screw portion 41 having a male screw formed on the outer peripheral portion is provided.

A hollow portion 43 that opens to one end side is provided at the axial center portion of the main body 33. The other end portion of the hollow portion 43 is connected to a communication hole 45 opened in the outer peripheral side surface portion of the main body 33 at a position on the other end side with respect to the protrusion portion 39.
A circumferential concave portion is formed in the outer peripheral side surface portion of the main body 33 at a position where the communication hole 45 is opened, and a sealing O-ring 35 is attached to the concave portion. The tightening force of the sealing O-ring 35 is adjusted to have a predetermined magnitude. When a pressure greater than the tightening force is applied from the communication hole 45, the sealing O-ring 35 moves to the outer peripheral side, and a gap is generated between the opening of the communication hole 45 and the sealing O-ring 35.

A circumferential recess is formed on one side surface of the protrusion 39, and a sealed O-ring 37 is attached to this recess.
A female screw into which the male screw of the screw part 41 is screwed is formed on the inner peripheral surface of the gas vent valve mounting hole 23.
Further, as shown in FIG. 8, a bolt 47 that is screwed into the gas vent valve mounting hole 23 is provided. By screwing the bolt 47, the gas vent valve mounting hole 23 can be completely sealed. A bolt 47 may be attached and the periphery of the head may be welded to the battery lid 15 to ensure sealing.
A gas vent valve 31 or a bolt 47 can be selectively mounted in the gas vent valve mounting hole 23.

[Reference embodiment as an assembled battery]
Next, a reference embodiment of an assembled battery using the lithium secondary battery 1 will be described.
The assembled battery 51 shown in FIG. 7 has a configuration in which four lithium secondary batteries 1 are connected in series. The assembled battery 51 is installed such that the battery cover 15 of the lithium secondary battery 1 is positioned on the upper surface.
The assembled battery 51 includes a case 53 having a substantially rectangular parallelepiped shape. FIG. 7 is a plan view showing a state in which a lid (not shown) that forms the upper portion of the case 53 is removed.

The case 53 has a partition in which the lithium secondary batteries 1 are stored at predetermined positions with a space therebetween. The adjacent lithium secondary battery 1 is lined upside down with respect to one lithium secondary battery 1. In other words, the long side portions LE1 or the long side portions LE2 of the adjacent lithium secondary batteries 1 are arranged adjacent to each other.
Thereby, the shortest distance between the positive electrode terminal 11 (negative electrode terminal 13) of one lithium secondary battery 1 and the negative electrode terminal 13 (positive electrode terminal 11) of the adjacent lithium secondary battery 1 can be obtained.
When the adjacent positive electrode terminal 11 and negative electrode terminal 13 are connected by the bus bar 55, the lithium secondary battery 1 is connected in series. At this time, since the distance between the positive electrode terminal 11 and the negative electrode terminal 13 connected by the bus bar 55 is the shortest distance, the length of the bus bar 55 connecting the two terminals can be shortened.

The monitoring unit 61 at the end of the assembled battery 51 is provided with a monitoring circuit (not shown) for monitoring the potential at each terminal and the temperature in each battery container. put out.
In the lithium secondary battery 1 used for the assembled battery 51, the battery lid 15 is positioned on the upper surface, so that the battery lid 15 does not directly contact the nonaqueous electrolytic solution 5. For this reason, since the original degassing function can be achieved, the degassing valves 31 are mounted in all the degassing valve mounting holes 23.
Moreover, although the case where the lithium secondary battery 1 is connected in series was described in this reference embodiment, the assembled battery may be configured by connecting the lithium secondary battery 1 in parallel by the same connection method. .

[One Embodiment as an assembled battery]
Next, an embodiment of an assembled battery using the lithium secondary battery 1 will be described.
The assembled battery 51 shown in FIG. 8 has substantially the same configuration as that of FIG. 7, but is installed so that the battery lid 15 of the lithium secondary battery 1 is located on the side surface of the lithium secondary battery 1. Is different. FIG. 8 is a front view showing the assembled battery.
That is, the monitoring unit 61 is set to be positioned at the top. In this case, the lower part of the battery lid 15 is in direct contact with the non-aqueous electrolyte 5, so that the gas vent valve mounting hole 23 located below each lithium secondary battery 1 is immersed in the non-aqueous electrolyte 5. become. For this reason, the gas vent valve mounting hole 23 is fitted with bolts 47 so that the gas vent valve mounting hole 23 is completely and reliably sealed. This prevents the nonaqueous electrolyte 5 from leaking outside.

A gas vent valve 31 is mounted in the gas vent valve mounting hole 23 located above each lithium secondary battery 1. Since the gas vent valve mounting hole 23 is provided at a position higher than the position (liquid level) of the liquid surface of the nonaqueous electrolytic solution 5, it does not directly contact the nonaqueous electrolytic solution 5.
Therefore, the degassing valve 31 can perform the original degassing function.
Further, even if the assembled battery 51 is rotated 90 degrees clockwise in the state of FIG. 8, that is, the short side portion SE1 or the short side portion SE2 is positioned in the vertical direction, , Can perform the original degassing function.

As described above, since the plurality of gas vent valve mounting holes 23 are provided, the position at which the gas vent valve 31 is mounted can be selected. That is, the gas vent valve 31 can be installed by selecting the gas vent valve mounting hole 23 located at an appropriate position.
Further, even if the battery container 3 is arranged so that the battery lid 15 faces the upper surface or the side surface, the gas vent valve 31 can be attached so as to perform an effective function.

Even if the battery cover 15 is arranged so that the adjacent sides, that is, the long side portions LE1 and LE2 and the short side portions SE1 and SE2 are positioned above, the gas vent valve 31 performs an effective function. Can be installed as.
In addition, since the battery cover 15 is substantially rectangular, if the gas vent valve mounting hole 23 is provided at the opposite corner as in the present embodiment, the gas vent valve regardless of which of the four sides comes up. 31 can be mounted to perform an effective function.

Therefore, the lithium secondary battery 1 to which the gas vent valve 31 is attached is connected in series or in parallel so as to perform an effective gas venting function regardless of whether the battery lid 15 is located on the upper surface or the side surface. The assembled battery 51 having various shapes can be configured.
Thereby, the assembled battery 51 of various forms can be provided according to the space shape of an installation place or usability.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  For example, in the present embodiment, the battery case 3 has a substantially rectangular parallelepiped shape, and thus the battery cover 15 has a substantially rectangular (rectangular, quadrilateral) shape. However, the shape of the battery cover 15 is not limited to this. Absent. What is necessary is just to have the edge which the battery cover 15 was divided, ie, the side which faces each other. For example, the battery lid 15 may have a polygonal shape including a triangle. Further, each of these sides may be a curved line instead of a straight line.

  In particular, in the case of an even-angled shape such as a rectangular shape, when two lithium secondary batteries 1 are arranged in the vertical direction or in the horizontal direction, one can be reversed from the other. Thereby, since it can arrange so that the other negative electrode terminal 13 may be located on one positive electrode terminal 11, the distance between both terminals can be shortened. Therefore, the length of the bus bar 55 connecting the two terminals can be shortened.

Further, in this embodiment, the gas vent valve mounting holes 23 that are close to the long side portions LE1 and LE2 or the short side portions SE1 and SE2 are provided at one location, but this is provided at a plurality of locations. Also good.
For example, it may be provided at the four corners of the battery lid 15.

It is a top view of the lithium secondary battery which concerns on one Embodiment of this invention. It is a front view of the lithium secondary battery which concerns on one Embodiment of this invention. It is the schematic diagram which showed typically the internal structure of the lithium secondary battery which concerns on one Embodiment of this invention. It is sectional drawing which shows the mounting state of the degassing valve which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the degassing valve which concerns on one Embodiment of this invention. FIG. 6 is an X view of FIG. 5. It is a top view which shows the state which removed the cover which forms the upper part of the case of the assembled battery which shows reference embodiment of this invention. Shows the setting置例of an assembled battery according to an embodiment of the present invention, it is a front view showing a state in which lid removed to form a front portion of the case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lithium secondary battery 3 Battery container 5 Non-aqueous electrolyte 7 Positive electrode 9 Negative electrode 11 Positive electrode terminal 13 Negative electrode terminal 15 Battery cover 23 Gas vent valve mounting hole 31 Gas vent valve 35 Sealing O-ring
47 Volts 51 Battery pack LE1, LE2 Long side

Claims (5)

A battery case having a box structure in which a positive electrode, a negative electrode, and a non-aqueous electrolyte are stored;
A lithium secondary battery comprising one surface of the battery container, and a battery lid attached so that a positive electrode terminal connected to the positive electrode and a negative electrode terminal connected to the negative electrode protrude. ,
These sides at positions close to the opposing sides of the battery lid and at positions above the liquid level of the non-aqueous electrolyte when one of these sides is located above the other. A plurality of mounting holes provided so as to penetrate the battery lid at least at one location corresponding to
A gas vent valve that is selectively mounted in the mounting hole located above the liquid level of the non-aqueous electrolyte among the plurality of mounting holes, and seals the opening with an elastic member;
Among the plurality of mounting holes, a bolt that is screwed into the mounting hole at a position to be immersed in the non-aqueous electrolyte and seals the mounting hole;
A lithium secondary battery comprising:   The lithium secondary battery according to claim 1, wherein the mounting hole is provided at a corner formed by adjacent sides. The mounting hole, a lithium secondary battery according to 請 Motomeko 2 you, characterized in that provided on the opposite corners.   The lithium secondary battery according to claim 1, wherein an O-ring is used as the elastic member.   A plurality of lithium secondary batteries according to any one of claims 1 to 4 are connected in series or in parallel.

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