JP2001257004A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which can discharge high-pressure gas passing through between an inner side face of a cylindrical body 1a of a battery case 1 and a side of a battery element outside a safety valve 5 through a side face concave part 7b and a bottom face concave part 7c of a spacer 7. SOLUTION: A spacer 7 provided with a side face concave part 7b at a side face as well as a bottom face concave part 7c at a bottom is inserted between a bottom plate 1c inside a battery case 1 and a battery element 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery in which a group of electrodes is housed in a battery case having a safety valve at the bottom, such as a large-sized lithium ion secondary battery.

[0002]

2. Description of the Related Art The structure of a conventional large-sized laminated lithium ion secondary battery will be described. This lithium ion secondary battery uses a vertically long rectangular parallelepiped battery case 1 as shown in FIG. The battery case 1 is made of a stainless steel plate, and is formed by fixing a square lid plate 1b and a bottom plate 1c to upper and lower open ends of a rectangular cylindrical body 1a by welding. Positive and negative terminals are fixed to the cover plate 1b so as to penetrate and project from the lower surface to the upper surface, respectively. These terminals are insulated from the cover plate 1b and are sealed between them. A safety valve 5 is provided at the center of the bottom plate 1c. The safety valve 5 includes the battery case 1
The battery case 1 is opened when the pressure inside the battery case 1 rises, and discharges the high-pressure gas inside the battery case 1 to the outside.

In the battery case 1, a stacked electrode group 2 shown in FIG. 7 is housed. This electrode plate group 2
A large number of positive electrodes 2a and negative electrodes 2b are laminated via a separator 2c. The positive electrode 2a is obtained by applying a positive electrode active material such as a lithium-cobalt composite oxide to the surface of an aluminum foil, and the negative electrode 2b is obtained by applying a negative electrode active material such as carbon to a surface of a copper foil. In addition, these positive electrodes 2
a and the negative electrode 2 b are respectively connected to the cover plate 1 inside the battery case 1.
b are respectively connected and fixed to the positive and negative terminals protruding below the lower surface of b.

In the lithium ion secondary battery having the above structure, when the battery is abnormal due to overcharge or overdischarge, the temperature of the electrode group 2 becomes high, and the highly reactive nonaqueous electrolyte filled in the battery case 1 is removed. Gas is generated. When the internal pressure of the battery case 1 rises to a predetermined value or more due to the generation of the gas, the safety valve 5 provided on the bottom plate 1c is opened to release the gas to the outside, thereby preventing the battery case 1 from being ruptured. Has become.

[0005]

However, the electrode group 2
Is stored in the battery case 1 in a state where the stacked positive electrode 2a and negative electrode 2b are pressed, so that the gas generated inside the battery case You can hardly get through. For this reason,
Most of the gas G generated in the upper part of the battery case 1 is substantially the cylindrical body 1a of the battery case 1, as shown by the arrow in FIG.
Move downward through the gap between the inner surface of the electrode group and the side of the electrode group 2, and when the gas G reaches the lower end, the electrode group 2
If the vehicle does not pass through a slight gap between the bottom portion of the base and the bottom plate 1c, the vehicle cannot go outside through the central safety valve 5.

For this reason, the conventional large-sized laminated lithium-ion secondary battery has a problem that gas generated inside the battery case 1 when the battery is abnormal cannot be discharged smoothly from the safety valve 5 of the bottom plate 1c to the outside. was there.

In the case of a battery using a wound electrode group, if the core of the electrode group is hollow,
Gas can be passed here, but if this core is blocked with a terminal rod or spacer, the same problem arises that the gas cannot be discharged smoothly from the safety valve on the bottom plate. I do.

The present invention has been made in order to cope with such a situation. By inserting a spacer having a gas vent passage between a bottom surface of a battery case and an electrode plate group, it is possible to prevent a battery from malfunctioning. An object of the present invention is to provide a battery capable of smoothly discharging gas generated inside from a safety valve on a bottom surface to the outside.

[0009]

According to a first aspect of the present invention, in a battery in which a group of electrode plates is housed inside a battery case provided with a safety valve on a bottom surface, a gas vent passage extending from a peripheral portion of an upper surface to a lower surface is formed. The spacer is arranged between the bottom surface and the electrode plate group inside the battery case.

According to the first aspect of the present invention, the gas generated inside when the battery is abnormal is passed between the inner surface of the battery case and the side of the electrode plate group, reaches the bottom, and from there, the upper surface of the spacer. Can easily reach the lower surface side through the gas vent passage opening to the peripheral edge of the valve, so that it can be smoothly discharged to the outside from the safety valve provided on the bottom surface.

According to a second aspect of the present invention, the gas vent passage is
One or more side recesses extending from the upper surface to the lower surface formed on the side surface of the spacer fitted to the inner surface of the battery case, and formed at the center of the lower surface of the spacer, and the peripheral edge reaches the side surface to reach each side. It is characterized by comprising a lower surface concave portion connected to the lower end of the side surface concave portion.

According to the second aspect of the present invention, the gas generated inside when the battery is abnormal passes through the space between the inner surface of the battery case and the side of the electrode plate group to the bottom, and from there the side surface of the spacer. Easily reaches the center of the bottom surface through the gap between the side surface recess formed in the battery case and the inner surface of the battery case and the gap between the bottom surface recess formed in the lower surface of the spacer and the bottom surface. As a result, the safety valve provided on the bottom surface can be smoothly discharged to the outside.

According to a third aspect of the present invention, a through hole is formed in the spacer, the central portion penetrating from the upper surface to the lower surface, and the lower end is connected to the lower surface concave portion.

According to the third aspect of the present invention, when the battery is abnormal, the gas generated at the bottom of the electrode group and the gas passing through the inside of the electrode group are not blocked by the spacer. Through the through hole formed in the center of the spacer, the safety valve provided on the bottom surface can be smoothly discharged to the outside.

According to a fourth aspect of the present invention, the electrode plate group includes a large number of positive and negative electrodes interposed between the opposed inner surfaces of the substantially rectangular parallelepiped battery case in parallel with the opposed inner surfaces of the battery case. It is characterized by being of a laminated type.

According to the fourth aspect of the present invention, in the case of a stacked electrode group, the gas can hardly pass through the inside, so that the gas reaching the bottom through the gap between the inner surface of the battery case and the bottom of the battery case. Can be smoothly discharged to the outside from the safety valve provided on the bottom surface.

According to a fifth aspect of the present invention, the electrode plate group has a large number of positive and negative electrodes disposed in parallel between the opposing inner surfaces of the battery case via a separator between opposing inner surfaces of the substantially rectangular parallelepiped battery case. The spacers are provided in such a manner that the spacers are provided with wide side recesses at one place on both side surfaces of the electrode plate group in the stacking direction, respectively.
It is characterized in that two side recesses each having a narrow width are provided on both side surfaces orthogonal to the laminating direction.

According to the fifth aspect of the present invention, in the case of a stacked electrode group, the electrodes tend to swell in the stacking direction as the battery is charged and discharged. In this case, it is possible to support the opposite side surfaces of the spacer that are going to be depressed by the protrusion between the two concave portions formed on the side surface of the spacer on the orthogonal side. Therefore, the depression of the side surface of the battery case prevents the gas from being difficult to pass between the inner surface and the electrode plate group, thereby ensuring a smooth gas release.

A pressure equalizing chamber, which communicates with the inside of the battery case through an opening formed in the bottom surface of the bottom surface of the battery case and can be expanded and contracted in response to an external pressure, is provided. And a safety valve is provided between the pressure equalizing chamber of the pressure equalizing device and the outside.

According to the sixth aspect of the invention, instead of providing a safety valve directly on the bottom surface of the battery case, if a safety valve is provided on the pressure equalizing device arranged below the battery case, the gas generated at the time of battery abnormality is also removed. It is possible to smoothly discharge the gas from the safety valve to the outside.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the present invention. FIG. 1 is a partial longitudinal sectional view showing a lower portion of a lithium ion secondary battery, FIG. 2 is a perspective view of a spacer, and FIG. FIG. 4 is a perspective view of a lithium ion secondary battery provided with a pressure equalizing device when viewed from below. FIG. 5 is a perspective view of a lower portion of the lithium ion secondary battery provided with a pressure equalizing device. It is a longitudinal cross-sectional view. Components having the same functions as those of the conventional example shown in FIGS. 6 and 7 are denoted by the same reference numerals.

In the present embodiment, a large-sized laminated lithium ion secondary battery will be described as in the conventional example. This lithium ion secondary battery has a battery case 1 including a vertically long rectangular parallelepiped tubular body 1a as shown in FIG. 6, and a lid plate 1b and a bottom plate 1c for closing upper and lower open ends of the tubular body 1a.
In FIG. 1, a stacked electrode group 2 as shown in FIG. However, in the lithium ion secondary battery of the present embodiment, a spacer 7 is inserted between the bottom plate 1c inside the battery case 1 and the electrode plate group 2. A safety valve 5 is provided at the center of the bottom plate 1c as in the conventional example.

As shown in FIGS. 2 and 3, the spacer 7 is a square plate material fitted into the battery case 1, and is made of insulating polypropylene.
However, if the positive electrode 2a and the negative electrode 2b of the electrode plate group 2 are reliably insulated from each other, a conductive material such as a metal plate can be used. The spacer 7 has a relatively large circular through hole 7a penetrating the center from the upper surface to the lower surface. Further, side recesses 7b are provided on the four side surfaces of the spacer 7, respectively. The side recess 7b
It is a groove formed shallowly and wide along the vertical direction on the side surface of the spacer 7, and a particularly wide side concave portion 7 b is provided on each of the opposing side surfaces, and on the other opposing side surfaces, Side recesses 7b each having a slightly smaller width are provided at two locations with an interval. Further, on the lower surface of the spacer 7, a lower surface concave portion 7c is provided.
The lower surface concave portion 7c is a wide groove formed on the lower surface of the spacer 7 vertically and horizontally, and the opposing side surface concave portions 7 on both opposing side surfaces.
A particularly wide lower surface recess 7c is provided between the two side surfaces so as to connect the lower ends of the lower surfaces b, and a slightly narrow lower surface recess 7c is formed between the two opposite side surfaces at a certain interval. It is provided in places. However, this spacer 7 has
Since the through hole 7a is formed, a portion where each lower surface recess 7c intersects at the center is connected to the lower end of the through hole 7a.

The spacer 7 is, as shown in FIG.
It is inserted into the battery case 1 such that the lower surface is placed on the bottom plate 1c. Then, only the portion of the lower surface of the spacer 7 protruding downward other than the lower surface recess 7c is the bottom plate 1c
A gap is left between the bottom plate 1c and the upper plate in contact with the upper plate. The four side surfaces of the spacer 7 fit into the inner surface of the cylindrical body 1a of the battery case 1 with almost no gap, but a gap is formed between the inner surface of the cylindrical body 1a and the side recess 7b. become. The electrode group 2 is placed and stored on the spacer 7.

Since the electrode group 2 is laminated by pressing the positive electrode 2a and the negative electrode 2b, there is almost no gap inside the electrode group 2. In addition, since the side portion of the electrode plate group 2 in the stacking direction is also in close contact with the inner surface of the cylindrical body 1a of the battery case 1,
There is no gap between them. However, this electrode group 2
As shown in FIG. 1, the side portion of the side perpendicular to the laminating direction has a small gap between the inner surface of the cylindrical body 1a and the side of the separator 2c interposed between the positive electrode 2a and the negative electrode 2b. Only the ends protrude. For this reason, when gas G is generated in the battery case 1 when the battery is abnormal, the gas G generated especially in the upper part is in contact with the side of the electrode plate group 2 on the side orthogonal to the stacking direction and the inner surface of the cylindrical body 1a. You can move downward through the space.

The bottom of the electrode plate group 2 is
The separator 2c, which is placed on and abuts on the upper surface of the substrate 2a and protrudes from between the positive electrode 2a and the negative electrode 2b, is also in a state of being in close contact to some extent. However, since the spacer 7 has side recesses 7b formed on four side surfaces, the gas G that has reached the lower end through the space between the side portion of the electrode plate group 2 and the inner surface of the cylindrical body 1a when the battery is abnormal. Can pass through the side recess 7b and beneath the spacer 7. In addition, since the lower surface of the spacer 7 is provided with the lower surface concave portion 7c connected to the lower end of each side surface concave portion 7b, the spacer 7 can pass through the lower surface concave portion 7c to reach the central portion of the bottom plate 1c.

Accordingly, when the internal pressure of the battery case 1 increases and the safety valve 5 provided on the bottom plate 1c is opened when the battery is abnormal, the lithium ion secondary battery of the present embodiment can The gas G generated inside passes between the side of the electrode plate group 2 on the side orthogonal to the laminating direction and the inner surface of the cylindrical body 1a of the battery case 1, and passes through the side recess 7b and the lower recess 7c of the spacer 7. The lever safety valve 5 is smoothly discharged to the outside. Further, the gas G generated at the lower part of the electrode plate group 2 and coming out from the bottom of the electrode plate group 2 can pass through the through hole 7a of the spacer 7, so that the gas G can smoothly flow from the safety valve 5 as in the related art. Can be released to the outside.

In the case of a conventional lithium ion secondary battery, when the battery is abnormal, the cylinder 1a of the electrode group 2 swells in the stacking direction, so that both sides of the cylinder 1a in the stacking direction are pushed from the inside. As a result, there is a fear that both side surfaces on the side orthogonal to the laminating direction are depressed and the passage of the gas G is further narrowed. However, the lithium ion secondary battery of the present embodiment has side recesses 7 on both sides of the spacer 7 on the side orthogonal to the stacking direction.
b are formed at two places each. For this reason, if both side surfaces of the cylinder 1a on the side orthogonal to the laminating direction are about to be depressed, the convex portion between the two side recesses 7b on the side surface of the spacer 7 supports the inner surface of the cylinder 1a. This makes it possible to secure a passage for the gas G.

When the above-mentioned large-sized lithium ion secondary battery is used in a high-pressure environment such as deep sea or the like, as shown in FIG. 6 must be installed. The equalizing device 6
As shown in FIG. 5, a cylindrical bellows 6a that can expand and contract in the vertical direction is fixed to the lower surface of the bottom plate 1c. And
An opening is provided at the center of the bottom plate 1c, so that the inside of the battery case 1 communicates with the inside of the bellows 6a. Therefore, when the external pressure changes, the bellows 6a of the pressure equalizing device 6 expands and contracts in accordance with the external pressure, so that the internal pressure of the battery case 1 and the external pressure can be kept in balance. Even under such a high-pressure environment, it is possible to prevent the battery case 1 from being broken by water pressure. Also,
In this case, the safety valve 5 is provided at the center of the bellows bottom plate 6b closing the lower end of the bellows 6a.

Even when the above-described pressure equalizer 6 is attached to a conventional lithium ion secondary battery, when the gas G generated at the time of battery abnormality passes through the opening of the bottom plate 1c,
Since the gap between the bottom of the electrode plate group 2 and the bottom plate 1c is narrow,
There has been a problem that the movement of the gas G in this part is hindered and smooth discharge cannot be performed. However, as shown in FIG. 5, if the spacer 7 of the present embodiment is inserted between the bottom plate 1c and the electrode plate group 2, the pressure inside the battery case 1 increases when the battery is abnormal, and When the safety valve 5 provided on the bellows bottom plate 6b of the pressure device 6 is opened, the gas G generated inside the battery case 1 passes between the side of the electrode group 2 and the inner surface of the cylindrical body 1a. Through the side recess 7b and the bottom recess 7c of the spacer 7, and through the opening of the bottom plate 1c, the bellows bottom plate 6b
Is smoothly discharged from the safety valve 5 provided to the outside.

In the above-described embodiment, the laminated electrode group 2 in which the gas G hardly passes is described. However, the wound electrode group 2 may be, for example, a central core part. In the case where the gas G is blocked, the release of the gas G through the side portion can be made smooth by using the spacer 7. In the above-described embodiment, the rectangular battery case 1 has been described. However, for example, when the wound electrode plate group 2 is used, the cylindrical battery case 1 can be used. The shape is not limited. Further, in the above-described embodiment, the case where the lower end opening of the cylindrical body 1a of the battery case 1 is closed by the bottom plate 1c has been described. However, a container-shaped battery case 1 in which the cylindrical body 1a and the bottom plate 1c are integrated is used. You can also. In the above embodiment, the lithium ion secondary battery has been described, but the present invention can be similarly applied to other types of batteries.

Further, in the above embodiment, the configuration of the safety valve 5 is not limited, but when the internal pressure of the battery case 1 rises and reaches a predetermined pressure or more, the inside of the battery case 1 is opened. Any structure may be used as long as the bottom plate 1c is partially thinned so that the bottom plate 1c can be broken at high pressure, or a structure using a pressure valve can be used. it can.

Further, in the above embodiment, the case where the through-hole 7a is formed in the spacer 7 is shown. However, in the case of the laminated electrode group 2, since the gas G coming out from the bottom is small, The through hole 7a may not be formed. In the above-described embodiment, the case where the groove-shaped side recess 7b and the lower surface recess 7c are formed in the spacer 7 has been described. However, the groove is not necessarily provided as long as the gas vent passage communicates from the upper peripheral edge to the lower surface of the spacer 7. Not only the shape but also a gas vent hole penetrating from the upper surface to the lower surface can be formed.

[0035]

As is apparent from the above description, according to the battery of the present invention, the gas generated at the time of abnormality of the battery and having passed through the space between the side surface of the battery case and the electrode plate group to the bottom portion is removed by the spacer. The gas can be smoothly discharged to the outside from the safety valve provided on the bottom plate through the gas vent passage.

[Brief description of the drawings]

FIG. 1, showing one embodiment of the present invention, is a partial longitudinal sectional view illustrating a lower portion of a lithium ion secondary battery.

FIG. 2 illustrates one embodiment of the present invention, and is a perspective view of a spacer.

FIG. 3, showing an embodiment of the present invention, is a perspective view of a spacer viewed from below.

FIG. 4, showing one embodiment of the present invention, is a perspective view of a lithium ion secondary battery provided with a pressure equalizing device as viewed from below.

FIG. 5, showing an embodiment of the present invention, is a partial longitudinal sectional view illustrating a lower portion of a lithium ion secondary battery provided with a pressure equalizing device.

FIG. 6 is a perspective view of a conventional example, showing a lithium ion secondary battery as viewed from below.

FIG. 7 is a partial longitudinal sectional view showing a conventional example and showing a lower portion of a lithium ion secondary battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 1a Cylindrical body 1c Bottom plate 2 Electrode group 5 Safety valve 6 Equalizing device 7 Spacer 7a Through hole 7b Side recess 7c Lower surface recess

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (6)

[Claims] 1. A battery in which a group of electrode plates is housed inside a battery case provided with a safety valve on a bottom surface, wherein a spacer having a gas vent passage extending from a peripheral portion of an upper surface to a lower surface is provided on a bottom surface inside the battery case. A battery characterized by being arranged between the electrode plate group. 2. The gas vent passage is formed at one or more side recesses from an upper surface to a lower surface formed on a side surface of a spacer fitted to an inner surface of a battery case, and at a central portion of the lower surface of the spacer. 2. The battery according to claim 1, further comprising a lower surface recess whose peripheral edge reaches each side surface and is connected to a lower end of each side surface recess. 3. 3. The battery according to claim 2, wherein a through-hole is formed in the spacer so that a central portion penetrates from the upper surface to the lower surface, and a lower end is connected to the lower surface concave portion. 4. A stacked type in which the electrode group is formed by laminating a large number of positive and negative electrodes in parallel with the opposed inner surfaces of the battery case via a separator between opposed inner surfaces of the substantially rectangular parallelepiped battery case. The battery according to any one of claims 1 to 3, wherein the battery is a battery. 5. A laminated type in which the electrode group is formed by laminating a large number of positive and negative electrodes in parallel with the opposed inner surface of the battery case via a separator between opposed inner surfaces of the substantially rectangular parallelepiped battery case. Wherein the spacers are provided on both sides of the electrode group in the laminating direction,
4. The method according to claim 2, wherein a wide side recess is provided at each one position, and narrow side recesses are provided at two places on both side surfaces orthogonal to the laminating direction. The battery as described. 6. A pressure equalizing chamber provided below a bottom surface of the battery case with an equalizing chamber communicating with the inside of the battery case through an opening formed in the bottom surface and capable of expanding and contracting according to an external pressure. The battery according to any one of claims 1 to 5, wherein a device is provided, and the safety valve is provided between a pressure equalizing chamber of the pressure equalizing device and the outside.