JPH07147155A - Square sealed battery - Google Patents

Abstract

PURPOSE:To prevent the peeling and dropping-out of an electrode material to prevent a short circuit by covering both flat surfaces of an U-shaped core body excluding the curved part and linear part where the core body is exposed with the electrode material containing an active material to constitute an U-shaped one-polar electrode plate. CONSTITUTION:An electrode body is formed of an U-shaped one-polar electrode 2 having an U-shaped core body 5 and a pair of flat electrode parts 4, the other plate 3 between the electrode parts 4, and a separator 6 between the electrode part 4 and the plate 3. The core body 5 is formed of the electrode part 4 having a flat part 5b whose whole surface is substantially covered with an one-polar electrode material layer 7, and a core body exposed part 5d consisting of a core body curved part 5a and a linear part 5c. When the electrode part 4 is a nickel electrode, the layer 7 is formed by filling a nickel active material 8 in the hole of a porous nickel sintered layer. One plate 3 is formed by covering the whole surface of a core body 11 with the other polar electrode material layer 12, and when the plate 3 is a cadmium positive electrode, the layer 12 is formed by filling a cadmium active material in the hole of the porous nickel sintered layer. Thus, the peeling and dropping-out of the electrode material by spring back can be suppressed to prevent a short circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prismatic sealed battery,
Particularly, it relates to improvement of the structure of the electrode.

[0002]

2. Description of the Related Art A prismatic sealed battery has an electrode body in which a plurality of positive and negative electrode plates having a flat plate shape are laminated via a separator, and has a higher volume efficiency than a cylindrical sealed battery. There is. This positive and negative electrode plate is often a sintered electrode plate in which the surface of the core is covered with an electrode material by sintering.For example, in the case of nickel and cadmium electrodes of a nickel-cadmium battery, the surface of the core is An active material is filled in the pores of a porous sintered layer formed by sintering nickel powder or the like, and as the active material, the nickel electrode is a nickel salt and the cadmium electrode is a cadmium electrode. Salt is used. Such a sintered electrode plate has excellent properties as an electrode plate, such as high porosity and specific surface area, high electric conductivity, and high mechanical strength.

By the way, in the prismatic sealed battery, these positive and negative electrode plates are electrically connected to each other with the same polarity,
It is connected to the external terminal. As a connecting method, a method of forming a conductive tab on an electrode plate and welding conductive tabs having the same polarity has been generally used. However,
In such a connection method, since it is necessary to provide a conduction tab for each electrode plate and a step of welding the conduction tab is also required, the method cannot be said to be excellent in productivity.

For this reason, in the prismatic closed battery disclosed in Japanese Patent Laid-Open No. 1-200552, a pair of opposing flat portions of a U-shaped core body formed by bending a central band portion of a flat plate has electrode plates of one polarity. Is formed, and an electrode body is formed by sandwiching another polarity electrode plate between the pair of electrode plates with a separator interposed therebetween. Therefore, when manufacturing such a prismatic sealed battery, it is not necessary to provide a conductive tab on the electrode plate of one polarity, and a welding process is also unnecessary, so that the productivity is greatly improved.

The electrode body for the prismatic sealed battery disclosed in this publication will be described with reference to FIG. As shown in the drawing, the electrode body 100 includes two flat plate-shaped negative electrode plate portions 101.
Two U-shaped negative electrodes 105 connected by a semi-cylindrical exposed core portion 101a (four negative electrode plate portions 101 are provided).
Sheet), three flat plate-shaped positive electrode plates 103, and one separator 102, and the negative electrode plate portions 101 and the positive electrode plates 103 are alternately laminated, and the separator 10 is interposed therebetween.
2 is inserted. Further, the three positive electrode plates 103 ...
The tips of the conduction tabs 103a attached to the respective positive electrode plates 103 are gathered together and connected to the positive electrode terminal.

The U-shaped negative electrode 105 comprises a pair of negative electrode plates 10
1.101 and a flat strip-shaped core body exposed portion 101a therebetween
Is manufactured by bending a strip-shaped core exposed portion 101a of the flat-plate negative electrode into a semi-cylindrical shape. Then, by inserting the electrode body 100 into the metal outer can, the exposed core portions 101a, 101a come into contact with the metal outer can, so that the metal outer can becomes the negative electrode terminal of the battery.

[0007]

A conventional electrode having a bent core exposed portion, such as the U-shaped negative electrode, is bent from the boundary between the flat electrode portion and the core exposed portion to form a core body. Due to the bent portion, the force to expand the electrode plate outward by spring back (see arrow A in FIG. 8)
Therefore, near the end of the electrode material layer (porous sintered layer) forming the electrode (in the U-shaped negative electrode 105, near the boundary between the negative electrode plate portion 101 and the exposed core material portion 101a). By the force of this springback, the electrode material was likely to be turned over or dropped outward. Then, the electrode material that is turned up or dropped comes into contact with the electrode plates of the positive electrode and the negative electrode, which causes a problem that a short circuit occurs inside the battery.

In view of the above-mentioned problems, the present invention prevents a short circuit in a battery in a prismatic sealed battery by preventing the electrode material from curling or falling off due to the force of the spring back of the core material of the U-shaped unipolar electrode. It is an object of the present invention to provide a prismatic sealed battery that hardly causes

[0009]

In order to solve the above problems, the present invention provides an electrode in which a U-shaped unipolar electrode plate having a pair of flat electrode portions is sandwiched with another polar electrode plate via a separator. In a prismatic sealed battery having a body inserted in an outer case, the U-shaped unipolar electrode plate has a pair of flat portions and a flat portion of a U-shaped core body having a bent portion provided between the flat portions. A flat electrode portion is formed by coating an electrode material containing an active material on a portion excluding the strip portion along the boundary with the bent portion, while the bent portion and the strip portion have exposed core bodies. Is characterized by.

[0010]

If the prismatic sealed battery according to the present invention has the structure U
In the U-shaped unipolar electrode plate, the bent and strip-shaped cores are exposed, so even if the springback force is exerted at the bent part, the electrode material is turned over from the place where no electrode material exists in the vicinity. -The occurrence of dropout is suppressed.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a perspective view showing a prismatic sealed battery according to Embodiment 1 of the present invention. For the sake of explanation, the front side of the paper surface of FIG. As shown in the figure, a prismatic sealed battery 10 includes an electrode body 1 in which another pole plate 3 is interposed between a pair of flat electrode portions 4 which are opposed to each other and stand upright.
3 are inserted into the rectangular metal outer can 9 in a state where they are arranged side by side with the planar electrode portions 4 adjacent to each other, and the upper surface of the metal outer can 9 is sealed with the sealing lid 13. Further, the metal outer can 9 also serves as a one-polarity terminal, and the sealing lid 1
The other pole terminal 14 insulated from this is attached to 3, and the electrolytic solution (not shown) is put in the metal outer can 9.

FIG. 2 is a diagram schematically showing the structure of the electrode body 1. As shown in the figure, an electrode body 1 is a U-shaped unipolar electrode 2 having a U-shaped core body 5 and a pair of flat electrode portions 4 and 4.
And the other electrode plate 3 interposed between the flat electrode portions 4 and 4, and the separator 6 interposed between the flat electrode portions 4 and 4 and the other electrode plate 3. Then, as shown in FIG.
The lower end of the U-shaped core body 5 is brought into contact with the metal outer can 9 so that the U-shaped unipolar electrode 2 is electrically connected to the metal outer can 9.

The U-shaped core 5 is formed by bending a rectangular flat plate made of punching metal at the central band so that the cross section viewed from the front is vertically long and vertically, and has a pair of opposed flat surfaces. Portions 5b and 5b are formed. The upper portion of the U-shaped unipolar electrode 2 is formed by covering substantially the entire surface of the flat portions 5b, 5b of the U-shaped core body 5 with the unipolar electrode material layer 7, and a pair of opposed rectangular planar electrodes. Part 4
4 and the lower part thereof is a core body exposed portion 5d in which the surface of the U-shaped core body 5 is not covered with the monopolar electrode material layer 7. The core body exposed portion 5d includes a core body bent portion 5a bent into a shape connecting the lower ends of the pair of flat surface portions 5b and 5b, and a flat strip-shaped exposed strip portion 5c formed by the lower portions of the flat surface portions 5b and 5b. And 5c.

The core bent portion 5a is bent in a U-shaped cross section having a horizontal surface at the lower end. Further, the exposed strip portion 5c has a flat strip shape that is long in the front-rear direction and is sandwiched between the lower end of the flat electrode portion 4 and the core body bent portion 5a. The upper and lower widths of the exposed strip portion 5c are such that the flat electrode portion 4 is not affected by the springback force of the core bent portion 5a. However, if the width is even a little, the effect is considered to occur.

Further, the unipolar electrode material layer 7 is, for example, a layer in which the nickel active material 8 is filled in the pores of the porous nickel sintered layer when the flat electrode portions 4 and 4 are nickel negative electrodes. Has been formed. The other electrode plate 3 is a rectangular sintered electrode having substantially the same size as that of the flat electrode portion 4, and is formed by coating the entire surface of the core 11 with the other polarity electrode material layer 12. Here, when the other electrode plate 3 is a cadmium positive electrode, the other polarity electrode material layer 12 is formed, for example, by filling the holes of the porous nickel sintered layer with the cadmium active material.

A conductive tab 12a is attached to the upper portion of the other electrode plate 3 and is attached to each of the three electrode bodies 1 ...
The two conductive tabs 12a ... Are joined together and connected to the other pole terminal 14 shown in FIG. In addition, the separator 6
Is a bag made of a polyolefin non-laying cloth having a shape that covers the entire surface of the other electrode plate 3 except the upper surface thereof. FIG. 3 is a schematic view showing an assembly process of the prismatic sealed battery 10. According to the figure
The assembly process of the prismatic sealed battery 10 will be described.

The other electrode plate 3 cut to a predetermined size is inserted into the bag-shaped separator 6 (see FIG. 3A). The manufacturing method of the U-shaped unipolar electrode 2 is as follows. First, a unipolar electrode material layer 7 is formed on a rectangular flat plate made of punching metal having a size corresponding to the U-shaped core body 5 by a sintering method or the like. A rectangular flat unipolar electrode 16 in which a pair of flat electrode portions 4 and 4 are formed sandwiching a central strip-shaped core body exposed portion 15d is manufactured as shown in FIG. Here, the size of the exposed core portion 15d is the same as the exposed core portion 5d.
It is formed so as to correspond to the size of. Then, the manufacturing method is, for example, after applying the nickel slurry to the entire rectangular flat plate made of punching metal, scraping off the nickel slurry in a corresponding place with a blade, and then sintering to form the exposed core portion 15d. be able to.
Then, the formed nickel sintered layer is filled with an active material such as a nickel active material 8 by a chemical impregnation method to form a unipolar electrode material layer 7.

Next, the exposed core portion 15d of the planar unipolar electrode 16 is bent into the shape of the exposed core portion 5d by a punch and a die of a bending jig to form a U-shaped unipolar electrode. 2 is formed (see FIG. 3B). The other electrode plate 3 inserted in the separator 6 is
The electrode body 1 is assembled by being sandwiched between the character-shaped unipolar electrodes 2 (see FIG. 3D).

Three electrode bodies 1 are lined up to form a metal outer can 9
, And the three conductive tabs 12a are joined to be electrically resistance welded to the other pole terminal 14. Then, the prismatic sealed battery 10 is manufactured by injecting the electrolytic solution into the metal outer can 9 and sealing it with the sealing lid 13, and laser-welding and sealing the fitting portion of the metal outer can 9 and the sealing lid 13 ( See FIG. 3 (e).

(Comparative Example) FIG. 7 is a front view showing an example of a rectangular sealed battery using a conventional U-shaped unipolar electrode. This prismatic sealed battery 40 is the same as the prismatic sealed battery 10 of the first embodiment except that the U-shaped unipolar electrode 42 ... Is used instead of the U-shaped unipolar electrode 2 ...
It has the same configuration as. Further, the U-shaped unipolar electrode 42 is
In the U-shaped unipolar electrode 2, the exposed core portion of the U-shaped core body 5 has an exposed strip portion instead of the exposed core portion 5d including the bent portion 5a of the core body and the exposed strip portions 5c and 5c. It is the semi-cylindrical exposed portion 45d of the core body, and the rest is U
The configuration is similar to that of the letter-shaped unipolar electrode 2.

(Experiment) Square sealed battery 10 of the above embodiment
Then, using the prismatic sealed battery 40 of the comparative example, a comparison test of the internal short circuit occurrence rate was performed. As for the inspection method, the voltage was measured after the battery had been assembled for a predetermined period of time, and when the voltage was less than the specified voltage, it was judged as a short circuit. As a result, the short-circuit rate was 0.01% for the prismatic sealed battery 10 and 0.14% for the prismatic sealed battery 40.
The short-circuit rate was lower than that of the rectangular sealed battery 40 of the comparative example.

As described above, the rectangular closed battery 10 of the embodiment has a lower short-circuit rate than the rectangular closed battery 40 of the comparative example is that in the rectangular closed battery 40, the core body exposed portion of the U-shaped core 5 is exposed. Since the entire 45d is a core refraction portion and does not have an exposed belt-like portion, the unipolar electrode material layer 7 is turned up or dropped off due to the spring back force of the core refraction portion, whereas In the sealed battery 10, since the U-shaped core body 5 has the exposed strip portions 5c and 5c, the spring back force of the core body bent portion 5a does not affect the flat electrode portion 4, and the unipolar electrode material is used. It is considered that this is because the occurrence of curling / falling off of the layer 7 is suppressed.

(Embodiment 2) FIG. 5 is a front view showing a prismatic sealed battery 20 according to Embodiment 2 of the present invention. The prismatic sealed battery 20 is the same as the prismatic sealed battery 10 of the first embodiment except that U
U-shaped unipolar electrode 22 ... Instead of U-shaped unipolar electrode 2 ...
The configuration is the same as that of the prismatic sealed battery 10 except that is used. Further, the U-shaped unipolar electrode 22 is the same as the U-shaped unipolar electrode 2 in that the bent portion of the U-shaped core body 5 is bent into a U-shaped cross section having a horizontal plane at the lower end. 5 has the same configuration as that of the U-shaped unipolar electrode 2 except that the bent body portion 25a having a V-shape shown in FIG. 5 is used instead of the exposed strip portions 5c and 5c. It has parts 25c and 25c.

Also in such a U-shaped unipolar electrode 22, the unipolar electrode material layer 7 is prevented from being turned over or dropped. (Embodiment 3) FIG. 6 is a front view showing a prismatic sealed battery 30 according to Embodiment 3 of the present invention. The prismatic sealed battery 30 is
The prismatic sealed battery 10 of Example 1 has the same configuration as the prismatic sealed battery 10 except that the U-shaped unipolar electrodes 32 ... Are used instead of the U-shaped unipolar electrodes 2. Further, the U-shaped unipolar electrode 32 is the core bent portion 5a of the U-shaped unipolar electrode 2 in which the bent portion of the U-shaped core body 5 is bent into a U-shaped cross section having a horizontal plane at the lower end. Instead of the semi-cylindrical core bent portion 35a shown in FIG. 6, it has the same configuration as the U-shaped unipolar electrode 2 and has the same exposed strip portion 35c as the exposed strip portions 5c and 5c.・
35c.

Also in such a U-shaped unipolar electrode 32, the unipolar electrode material layer 7 is prevented from being turned over or dropped. In addition, in the prismatic sealed battery in the above embodiment, the U-shaped unipolar electrode is a negative electrode and the sintered electrode in which the electrode material layer is a sintered layer is shown, but the prismatic sealed battery of the present invention is not limited to this. Alternatively, the U-shaped unipolar electrode may be a positive electrode, or an electrode in which an electrode material is applied to a core material can be similarly used, and the same effect can be obtained.

[0026]

EFFECTS OF THE INVENTION The prismatic sealed battery according to the above-described configuration of the present invention is the conventional U-shaped unipolar electrode formed by bending the exposed core body, and has an improved structure of the exposed core body. It is a prismatic sealed battery that suppresses the electrode material from curling and falling off, and prevents the occurrence of short circuits inside the battery.

[Brief description of drawings]

FIG. 1 is a perspective view showing a prismatic sealed battery according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing the structure of an electrode body 1.

FIG. 3 is a schematic view showing an assembly process of the prismatic sealed battery 10.

FIG. 4 is a perspective view showing a planar unipolar electrode 16.

FIG. 5 is a front view showing a prismatic sealed battery 20 according to a second embodiment of the present invention.

FIG. 6 is a front view showing a prismatic sealed battery 30 according to a third embodiment of the present invention.

FIG. 7 is a front view showing an example of a rectangular sealed battery using a conventional U-shaped unipolar electrode.

FIG. 8 is a perspective view showing an example of a rectangular sealed battery using a conventional U-shaped unipolar electrode.

[Explanation of symbols]

 2 U-shaped unipolar electrode 4 Planar electrode part 5 U-shaped core body 5a Core bent part 5b Flat part 5c Exposed strip part 7 Electrode material 8 Nickel active material

Claims (1)

[Claims] 1. A prismatic sealed battery in which an electrode body in which a U-shaped unipolar electrode plate having a pair of flat electrode portions and another polarity electrode plate sandwiched by a separator is inserted in an outer case, The U-shaped unipolar electrode plate has a pair of flat portions and a direction along the boundary with the bent portion on the flat portion of the U-shaped core having a bent portion provided between the flat portions. Except for the strip-shaped portion along the entire length, an electrode material containing an active material is coated to form the planar electrode portion, while the bent portion and the strip-shaped portion have a core body exposed, which is a prismatic seal. battery.