JP2003017115A - Sealed secondary cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed secondary cell aiming at an improvement of life property by restraining a dry up of electrolyte liquid. SOLUTION: For the sealed secondary cell housing and sealing a group of electrodes 5 and electrolyte liquid in a cell case 3, a porous body 20 in which, electrolyte liquid is absorbed, is arranged in contact with the group of electrodes 5 in the cell case 3 so as to replenish electrolyte liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed secondary battery, and more particularly to a sealed secondary battery which suppresses electrolyte depletion and improves life characteristics.

[0002]

2. Description of the Related Art A nickel-hydrogen secondary battery is known as a sealed secondary battery, and is a collective sealed battery in which a plurality of single cells are connected and integrally configured to obtain a required power capacity. The present applicant has previously proposed a secondary battery having a structure as shown in FIG.

As shown in FIG. 6, an assembled sealed secondary battery 1
Is a plurality of rectangular parallelepiped-shaped battery cells 3 (six in the illustrated example) having a narrow short side surface and a wide long side surface, and the short side surfaces are shared as partition walls, and are integrally connected to each other. The prismatic battery case 2 is formed, and the upper surface opening of each battery case 3 is integrally closed by a lid 4. In each battery case 3, an electrode plate group 5 formed by stacking a large number of positive electrode plates and negative electrode plates parallel to the long side surface of the battery case 3 in the direction of the short side surface via a separator is housed together with an electrolytic solution, and a single battery is stored. 6 are configured.

Positive and negative electrode current collectors 7 are provided on both sides of the electrode plate group 5.
Are joined. The upper end portion of the current collector 7 projects upward from the electrode plate group 5, and the current collectors 7 facing each other with the partition wall interposed therebetween are connected through the connection holes formed in the upper end portions of the partition walls between the battery cases 3 and 3. It is connected. Further, a positive or negative connection terminal 8 is attached to a connection hole formed at the upper end of the short side surface outside the battery case 3 at both ends of the rectangular battery case 2, and the collector 7 on the inner side of the short side surface is connected. It is connected to the upper end portion and the individual cells 6 are connected in series.

The lid 4 has a single safety valve 1 for releasing the pressure in each battery case 3 when the internal pressure exceeds a certain level.
0 is provided, and a sensor mounting hole 11 for mounting a temperature detection sensor for detecting the temperature of the unit cell 6 is formed so as to be in contact with the upper end of the electrode plate group 5 of the appropriate unit cell 6. Further, on the upper surface of the lid body 4, through holes 15 are formed at the adjacent end portions of the battery cases 3 and 3 that are adjacent to each other, and the lid body 4 is formed.
A communication portion 16 that communicates between the through holes 15 and 15 is provided above.

On the long side surface 12 of the integrated battery case 2 in which the long side surface of each battery case 3 forms a plane, ribs 13 extending vertically are provided at positions corresponding to both side ends of each battery case 3. In addition, between the ribs 13 and 13, a large number of relatively small circular projections 14 are projected in a matrix at an appropriate pitch, and when the ribs 13 and 14 project the integrated battery case 2 in parallel, A coolant passage for efficiently and uniformly cooling each battery case 3 is formed between them.

[0007]

By the way, in the assembled type sealed secondary battery 1 shown in FIG. 6, in order to make the movement of hydrogen gas due to charging and discharging uniform and smooth, liquid is poured into the battery case 3. Almost the entire amount of the generated electrolytic solution is absorbed and held by the separator and the electrode plates of the electrode plate group 5, and there is almost no free electrolytic solution. Therefore, the electrolyte solution is absorbed by the positive electrode plate expanded by charge and discharge, or consumed by the corrosion of the hydrogen storage alloy, so that the electrolyte solution amount in the separator is gradually reduced and exhausted. When the amount of electrolyte in the separator is exhausted in this way, the internal resistance of the battery rises,
There is a problem that the life characteristics are deteriorated.

Therefore, it is conceivable to replenish the electrolytic solution, but it is practically difficult because it is a sealed secondary battery.

In view of the above conventional problems, it is an object of the present invention to provide a sealed secondary battery which suppresses electrolyte depletion and improves life characteristics.

[0010]

The sealed secondary battery of the present invention is a sealed secondary battery in which a group of electrode plates and an electrolytic solution are housed and sealed in a battery case. A porous body that has absorbed the electrolytic solution is arranged in contact with the group.When the electrolytic solution in the separator decreases, the electrolytic solution absorbed in the porous body is replenished, so that the electrolyte in the separator is depleted. Therefore, the internal resistance of the battery can be prevented from increasing and the life characteristics can be improved.

The amount of electrolytic solution absorbed by the porous body is 0.3 g.
When / Ah or more, the effect of improving the life characteristics is remarkably obtained, which is preferable. Note that the upper limit is about 0.5 g / Ah in view of volumetric efficiency, because the battery case volume becomes large in order to secure the accommodation space for the porous body.

Further, the electrode plate group is constructed by laminating a rectangular positive electrode plate and a negative electrode plate with a separator interposed therebetween, and the lead portions of the positive electrode plate and the negative electrode plate are projected to the opposite side portions to collect current. When the body is joined and the porous body is arranged on the upper part, the lower part, or both of the electrode plate group, the current collectors are arranged on both sides of the electrode plate group. Since the distance can be shortened to reduce the internal resistance, and the electrolyte can be replenished from either or both of the upper and lower parts of the electrode plate group where the current collector is not arranged, the internal resistance is small and It is possible to prevent an increase in internal resistance for a long period of time and obtain a sealed secondary battery having a long life.

Further, a plurality of rectangular parallelepiped battery cells are integrally connected to each other with the short side surfaces as partition walls, and the upper ends of the current collectors on both sides of the partition walls are connected to each other between the unit cells of each battery cell. Is
If a porous body is placed in the space between the upper ends of the current collectors on the electrode plate group in each battery case, the gap between the upper ends of the current collectors projected above the electrode plate group so as to connect between the single cells. Since the porous body is arranged by utilizing the space, it is possible to obtain a sealed secondary battery having long life characteristics with good volume efficiency.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of an assembled sealed secondary battery composed of a nickel-hydrogen secondary battery, which can be preferably used as a driving power source for an electric vehicle, will be described below with reference to FIGS. Will be described with reference to. The same components as those of the conventional example described with reference to FIG. 6 are designated by the same reference numerals and description thereof will be omitted.

The assembled sealed secondary battery 1 of this embodiment is
As shown in FIGS. 1 to 3, the electrode plate group 5 is provided in each battery case 3 of the rectangular battery case 2 in which a plurality of battery cases 3 are commonly connected to each other by using the short side faces thereof as partition walls. It is configured to be stored together with the electrolytic solution.

Connection holes 17 are formed in the outer short side surfaces of the battery case 3 at both ends of the rectangular battery case 2 and in the upper ends of the short side surfaces between the battery cases 3 and 3, and are connected to both sides of the electrode plate group 5. A connecting projection 18 formed on the upper ends of the positive electrode and negative electrode current collectors 7 (7a, 7b) is fitted into the connection hole 17, and the tips thereof are welded to each other to form a single cell of each battery case 3. 6 are connected in series.

As shown in FIG. 2, the electrode plate group 5 includes a plurality of positive electrode plates and a plurality of negative electrode plates alternately arranged, and each positive electrode plate is covered with a bag-shaped separator having an opening in the lateral direction. By the above, the positive electrode plate and the negative electrode plate are laminated with a separator interposed therebetween, and the positive electrode plate group and the negative electrode plate group have opposite side edge portions protruding outward and the protruding side edge portions being the positive electrode. The negative electrode lead portions 5a and 5b are formed, and collectors 7a and 7b each made of a plate material are welded to the side edges thereof.

The positive electrode plate is made of Ni foam metal and the lead portion 5
It is configured by filling an active material containing nickel hydroxide except a, and the lead portion 5a is configured by pressurizing and compressing a foam metal and ultrasonically welding a lead plate to one surface thereof. Further, the negative electrode plate is formed by coating a punching metal of Ni with a component containing a hydrogen storage alloy except for the lead portion 5b.

In each battery case 3, a porous body 20 absorbing the electrolytic solution is disposed in contact with the electrode plate group 5 in the space 19 between the upper ends of the current collectors 7a, 7b on the electrode plate group 5. There is. The amount of electrolytic solution absorbed by the porous body 20 is set to 0.3 g / Ah or more.

The porous body 20 is composed of a non-woven fabric, a sponge, or the like, which is a porous film forming a separator. When the battery capacity of the single battery 6 is 6.5 Ah, the amount of the electrolyte solution absorbed is about 2 g cells or more, and the volume is 1.5 c.
Since it is about c or more, and the volume of the porous body 20 is about twice that of the porous body 20, a space of 3.0 cc or more is required for each battery case 3, but between the upper ends of the current collectors 7a and 7b. Space 19
Has such a size.

In the assembled type sealed secondary battery 1 having the above-mentioned structure, the porous body 20 which is in contact with the electrode plate group 5 and absorbs the electrolytic solution is arranged in the battery case 3, and therefore the electrode plate group 5 is arranged. When the amount of the electrolytic solution in the separator is reduced, the electrolytic solution absorbed in the porous body 20 is replenished, so that the electrolytic solution in the separator can be prevented from being depleted, the internal resistance of the battery can be prevented from increasing, and the life characteristics can be improved. Can be improved.

In FIG. 5, in the conventional example in which the porous body 20 was not provided, the internal resistance began to increase at about 3000 cycles and doubled at about 4500 cycles to reach the end of life. By setting the amount of the electrolyte solution absorbed by the body 20 to 0.3 g / Ah, the internal resistance starts to increase at about 3500 cycles, and the internal resistance doubles at 5000 cycles or more to extend the life and improve the life characteristics. Furthermore, when 0.5 g / Ah is set, the life characteristics such that the internal resistance does not start to increase until about 5000 cycles can be obtained, but the battery capacity of the single battery 6 is 6.5 A.
In the case of h, the volume of the porous body 20 needs to be about 5 cc,
While exceeding the required life characteristics, the volume efficiency deteriorates. Therefore, it is preferable that the amount of electrolyte is about 0.3 to 0.5 g / Ah.

Further, in this embodiment, the electrode plate group 5 is formed by laminating rectangular positive electrode plates and negative electrode plates with a separator interposed therebetween, and the lead parts 5a and 5b of the positive electrode plate and the negative electrode plate are arranged on opposite sides of each other. Since the current collectors 7a and 7b are joined so as to project to the side and the porous body 20 is disposed above the electrode plate group 5, the average distance from the entire surface of the electrode plate to the current collectors 7a and 7b Can be shortened to reduce the internal resistance value of the battery, the utilization factor of the electrode active material can be increased to improve the battery output, and the electrode plate group 5 having no current collectors 7a and 7b can be used. Since the electrolytic solution can be replenished from the upper portion, the internal resistance is small and the internal resistance can be prevented from increasing for a long period of time, and a sealed secondary battery having a long life characteristic can be obtained.

Further, a plurality of rectangular parallelepiped battery containers 3 are integrally connected to each other with their short side faces as partition walls, and the current collectors 7a on both sides of the partition walls are provided between the unit cells 6 of each battery container 3. The upper ends of 7b are connected to each other, and the current collector 7 on the electrode plate group 5 in each battery case 3 is connected.
Since the porous body 20 is disposed by utilizing the space 19 between the upper ends of a and 7b, the connection resistance between the unit cells 6 and 6 can be reduced, and the number of parts can be reduced and the cost can be reduced easily. It is possible to connect and obtain long life characteristics with good volume efficiency.

As described above, according to the present embodiment, the internal resistance per unit cell 6 can be suppressed to a low level, whereby heat generation of the battery can be reduced, high output can be realized, and electrolyte replenishment can be achieved. The life characteristics can be improved.

In the above embodiment, an example in which the porous body 20 is provided only on the upper part of the electrode plate group 5 is shown, but as shown in FIG. It may be arranged, and may be arranged in the upper part, the lower part, or both as necessary.

[0027]

According to the sealed secondary battery of the present invention, as is apparent from the above description, since the porous body which is in contact with the electrode plate group and absorbs the electrolytic solution is arranged in the battery case, the separator is When the amount of the electrolytic solution in the separator decreases, the electrolytic solution absorbed by the porous body is replenished, the exhaustion of the electrolytic solution in the separator can be prevented, the internal resistance of the battery can be prevented from increasing, and the life characteristics can be improved.

Further, the electrode plate group is constructed by stacking rectangular positive electrode plates and negative electrode plates with a separator interposed therebetween, and the lead portions of the positive electrode plate and the negative electrode plate are projected to opposite side parts to collect current. When the body is joined and a porous body is arranged on the upper part, the lower part, or both of the electrode plate group, the current-carrying distance can be shortened, the internal resistance can be reduced, and the upper part of the electrode plate group without the current collector can be reduced. Since the electrolytic solution can be replenished from either or both of the lower part and the lower part, it is possible to obtain a sealed secondary battery having a small internal resistance and preventing the internal resistance from rising for a long period of time, and having a long life characteristic.

Furthermore, when a porous body is arranged in the space between the upper ends of the current collectors on the electrode plate group in each battery case, the current collectors projected above the electrode plate groups so as to connect the unit cells. Since the porous body is arranged by utilizing the space between the upper end portions of the body, it is possible to obtain a sealed secondary battery having high volume efficiency and long life characteristics.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of an embodiment of a sealed secondary battery of the present invention.

FIG. 2 is a perspective view showing a state in which a current collector is joined to the electrode plate group of the same embodiment.

FIG. 3 is a vertical sectional front view of a main part in the same embodiment.

FIG. 4 is a vertical sectional front view showing a schematic configuration of a modified example of the same embodiment.

FIG. 5 is a cycle characteristic diagram of the same embodiment and a conventional example.

FIG. 6 is a partially cutaway perspective view of a conventional sealed secondary battery.

[Explanation of symbols]

1 Assembly type rechargeable battery 3 battery case 5 plate group 6 cells 7 (7a, 7b) Current collector 19 space 20 Porous body

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichi Yuasa             Panasonic, 555 Sakaijuku, Kosai City, Shizuoka Prefecture             EV Energy Co., Ltd. (72) Inventor Katsunori Komori             Panasonic, 555 Sakaijuku, Kosai City, Shizuoka Prefecture             EV Energy Co., Ltd. (72) Inventor Kojiro Ito             Panasonic, 555 Sakaijuku, Kosai City, Shizuoka Prefecture             EV Energy Co., Ltd. (72) Inventor Tokuyuki Fujioka             Panasonic, 555 Sakaijuku, Kosai City, Shizuoka Prefecture             EV Energy Co., Ltd. (72) Inventor Yasuhiro Takahashi             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F term (reference) 5H022 AA04 BB11 CC14                 5H028 AA01 AA06 CC00 CC08 HH10

Claims (4)

[Claims] 1. A hermetically sealed secondary battery in which an electrode plate group and an electrolytic solution are housed and hermetically sealed in a battery case, and a porous body which is in contact with the electrode plate group and absorbs the electrolytic solution is disposed in the battery case. A sealed secondary battery characterized in that 2. The amount of electrolytic solution absorbed by the porous body is 0.3.
The sealed secondary battery according to claim 1, wherein g / Ah or more is set. 3. The electrode plate group is formed by laminating a rectangular positive electrode plate and a negative electrode plate with a separator interposed therebetween, and the lead portions of the positive electrode plate and the negative electrode plate are projected to the opposite side portions to collect electricity. The sealed secondary battery according to claim 1 or 2, wherein the bodies are joined, and a porous body is arranged on the upper portion, the lower portion, or both of the electrode plate group. 4. A plurality of rectangular parallelepiped battery cells are integrally connected to each other with their short side surfaces as partition walls, and the upper ends of the current collectors on both sides of the partition walls are connected to each other between the unit cells of each battery cell. The sealed secondary battery according to claim 3, wherein a porous body is provided in a space between the upper ends of the current collectors on the electrode plate group in each battery case.