JPH0864233A - Square-shaped battery - Google Patents

Abstract

PURPOSE: To provide a square-shaped battery excellent in assemblability, preventing the displacement of electrodes and an internal short circuit during the assembling process, and capable of preventing the defective welding of an upper cover. CONSTITUTION: An upper cover 21 is fitted on one end side of a chassis 20, and the chassis 20 is provided with an open section for inserting an electrode group, folding pieces 20a for closing the open section, and an opening section 20c below the upper cover 21. The electrode group constituted of a positive electrode plate 10 and a negative electrode plate 14 is inserted into the chassis 20 through the open section, then the folding pieces 20a are folded to press the electrode group, and the electrode group is stored and fixed in the chassis 20. The positive electrode and negative electrode current collecting terminals 13, 17 of the positive and negative electrode plates 10, 14 are connected to a positive electrode terminal 3 or the chassis 20 via lead plates through the opening section 20c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prismatic battery used as a power source for various electronic devices.

[0002]

2. Description of the Related Art Conventionally, small secondary batteries have been widely used as a power source for portable electronic equipment such as office automation equipment, factory automation equipment, home appliances, and communications. There is a demand for prismatic secondary batteries that can be made more compact and lighter.

FIG. 9 is a cross-sectional view showing a conventional rectangular nickel-cadmium battery. In the figure, reference numerals 1 and 2 respectively show a current collector coated with or impregnated with an active material, and a plurality of separators (not shown) are alternately arranged. Arranged negative plate and positive electrode, 3
Is a positive electrode current collecting ear portion 4 of each of the plurality of positive electrodes 2.
And a positive electrode terminal 6 electrically coupled together through a positive electrode lead plate 5, and 6 electrically coupled together through a protruding negative electrode current collecting ear 7 of each of the plurality of negative electrodes 1 and a negative electrode lead plate 8. It is a rectangular negative electrode terminal, and this negative electrode terminal 6 also serves as a battery case. Reference numeral 9 denotes an upper lid provided with the positive electrode terminal 3 electrically insulated, and the upper lid 9 has an opening edge of the negative electrode terminal 6 after the negative electrode plate 1 and the positive electrode plate 2 which are stacked are housed in the negative electrode terminal 6. It is welded to the portion and is hermetically integrated with the negative electrode terminal 6. As a similar example, a prismatic sealed nickel-cadmium battery described in Battery Technology (1989, first issue, p.62-80, Electrochemical Society Battery Technology Committee).

In order to assemble the prismatic nickel-cadmium battery having such a structure, first, a plurality of positive electrode plates 2 and negative electrode plates 1 are alternately stacked with a separator interposed therebetween and inserted into a negative electrode terminal 6 which also serves as a battery case. . Then, the positive electrode current collecting ears 4 of the plurality of positive electrode plates 2 are assembled and electrically connected to the positive electrode terminal 3 via the positive electrode lead plate 5, and the respective negative electrode current collectors of the plurality of negative electrode plates 1 are collected. Collect the ear parts 7,
Negative electrode terminal 6 that doubles as a battery case via the negative electrode lead plate 8
Electrically connect to. Further, the upper lid 9 is positioned and fixed by being supported from below by the positive electrode current collector ear portion 4 and the positive electrode lead plate 5, and the edge portion of the upper lid 9 and the opening edge portion of the negative electrode terminal 6 also serving as the battery case are welded and hermetically sealed. A square nickel cadmium battery is obtained. This conventional nickel-cadmium battery
When the prismatic battery is configured as described above and mounted in a device, the four corners that become dead spaces in the cylindrical battery contribute to the capacity in the prismatic battery, and thus achieve a substantially high energy density. .

However, due to the demand for higher performance of the battery, a lithium secondary battery having high energy density, high voltage and excellent long-term storability is required. 10 and 11 are partially cutaway plan views showing the structures of a positive electrode plate and a negative electrode plate in a conventional prismatic lithium secondary battery, respectively.
Is a collector plate 1 made of a thin plate such as aluminum or stainless steel
A positive electrode plate composed of 1 and its collector plate 11 and a rechargeable / dischargeable positive electrode active material 12 formed by, for example, coating MnO ₂ composited with lithium, and a positive electrode plate 13 protruding above the positive electrode plate 10. The provided positive electrode current collecting ear portion 14 is a current collecting plate 15 made of a thin plate of copper, nickel, or the like, and a negative electrode active material 16 made of carbon capable of inserting and extracting lithium ions formed on the current collecting plate 15 by coating. Negative electrode plate, 17 is negative electrode plate 1
4 is a negative electrode current collecting ear portion provided so as to project above the upper portion of No. 4.

In order to assemble the conventional prismatic lithium secondary battery having such a structure, first, a plurality of positive electrode plates 10 and negative electrode plates 14 are alternately stacked via a separator to form a negative electrode terminal 6 also serving as a battery case. Insert inside. Then, the positive electrode current collecting ears 13 of the plurality of positive electrode plates 10 are assembled and electrically connected to the positive electrode terminal 3 via the positive electrode lead plate 5, and the negative electrode current collectors of the plurality of negative electrode plates 14 are collected. Electric ear 17
Are assembled and electrically connected via the negative electrode lead plate 8 to the negative electrode terminal 6 which also serves as a battery case. Further, the upper lid 9 is positioned and fixed by being supported from below by the positive electrode current collecting ear 13 and the positive electrode lead plate 5, and the edge portion of the upper lid 9 and the opening edge portion of the negative electrode terminal 6 also serving as the battery case are welded and hermetically sealed. A square lithium secondary battery is obtained. At this time, the separator interposed between the positive electrode plate 10 and the negative electrode plate 14 is impregnated with an organic electrolytic solution, for example, a mixed solvent of ethylene carbonate and dimethoxyethane. The separator is made of a microporous film such as polypropylene or polyethylene or a non-woven fabric. In addition to the MnO ₂ composited with lithium, the positive electrode active material 12 is an oxide or sulfide such as V ₂ O ₅ , TiS ₂ , MoS ₂ composited with lithium composited with lithium, or polyaniline or polypyrrole. Conductive polymers such as Further, as the negative electrode active material 16, in addition to carbon, lithium metal, a lithium aluminum alloy, or an alloy of lithium and another element is used.

In this conventional prismatic lithium secondary battery, during discharge, the lithium ions stored in the negative electrode active material 16 of the negative electrode plate 14 are desorbed into the electrolytic solution, and the lithium ions are positively active in the positive electrode plate 10. While being occluded in the substance 12, during charging, lithium ions are desorbed from the positive electrode active material 12 and released into the electrolytic solution, and occluded in the negative electrode active material 16 of the negative electrode plate 14 to perform charging / discharging operation. .

[0008]

Since the conventional prismatic lithium secondary battery uses the organic electrolyte as the electrolyte as described above, the conductivity of the electrolyte is poor and charging / discharging with a large current is not possible. In order to make it possible, it is necessary to make the electrode areas of the positive electrode plate 10 and the negative electrode plate 14 larger than those of the conventional rectangular nickel cadmium battery. As a result, the number of electrodes to be stacked inevitably increases, and the electrodes also need to be thin,
A thin metal foil having a thickness of about 10 to 30 μm was used as a base material for the current collectors 11 and 15. Therefore, since the current collectors 11 and 15 are made of thin metal foil, the laminated positive electrode plates 1
When inserting the electrode group of 0 and the negative electrode plate 14 into the battery case, there was a problem that the strength of the electrode itself becomes weak and the electrode is bent or displaced to cause an internal short circuit.

Further, as a manufacturing problem, there is a problem of welding failure between the upper lid 9 and the battery case. That is,
In order to obtain stable welding between the upper lid 9 and the battery case,
Positioning and fixing of the upper lid 9 before welding is an important factor,
In the conventional rectangular nickel-cadmium battery, since the thickness of the electrodes and the current collecting ears is large and the strength of the electrodes themselves is strong, the upper lid 9 is firmly fixed from below by the positive electrode current collecting ears 4 of the positive electrode plate 2 and the positive electrode lead plate 5. Positioned and fixed by being supported by, it is possible to perform stable welding without moving during welding. However, in the conventional prismatic lithium secondary battery, the thickness of the electrodes and the collecting ears is thin, and the strength of the electrodes themselves is weak. There is also a problem that the upper lid 9 becomes unstable, the upper lid 9 moves during welding, and the position of the upper lid 9 is displaced, resulting in defective upper lid welding.

The present invention has been made in order to solve the above problems, and improves the workability of assembling a battery, and prevents displacement of electrodes and internal short circuit in the battery assembling process. Moreover, it is an object of the present invention to obtain a prismatic battery capable of suppressing the occurrence of top lid welding failure.

[0011]

According to a first aspect of the present invention, a prismatic battery is housed in a prismatic battery case in which a plurality of negative electrode plates and positive electrode plates are alternately stacked with a separator interposed therebetween. In the rectangular battery, the chassis is housed in the rectangular case by accommodating and fixing the rectangular case that also serves as one battery terminal having an opening at one end and the laminated negative electrode plate and positive electrode plate. And an upper lid integrally attached to one end side of the chassis, and the other battery terminal electrically insulated from the upper lid, and the upper lid integrated with the chassis housed in the rectangular case. The edge portion and the opening edge portion of the rectangular case are welded and hermetically integrated, and one of the laminated negative electrode plate and positive electrode plate is electrically assembled through a lead plate. Connected to the chassis and stacked negative plate and positive The other electrode plate group of the plate are those that are electrically set via the lead plate is connected to the other battery terminal.

[0012] A prismatic battery according to a second aspect of the present invention is the prismatic battery according to the first aspect, wherein the chassis has an open portion into which the laminated negative electrode plate and positive electrode plate are inserted, and the open portion. A bending piece for bending the negative electrode plate and the positive electrode plate to press and fix the negative electrode plate and the positive electrode plate, and an opening portion provided on the lower surface side of the upper lid so that one end side of the inserted negative plate plate and the positive electrode plate are exposed. It is a thing.

Further, a prismatic battery according to a third aspect of the present invention is the prismatic battery according to the first aspect of the present invention, wherein the chassis has an open portion into which the laminated negative electrode plate and positive electrode plate are inserted and the inserted negative electrode plate. Chassis body having an opening provided on the lower surface side of the upper lid so that one end side of the positive electrode plate and the positive electrode plate are exposed, and the negative electrode plate and the positive electrode plate are attached to the chassis body so as to close the opening portion to form the negative electrode plate and the positive electrode plate. And a chassis lid that is press-fixed between and.

[0014]

In the first aspect of the present invention, the battery case is a rectangular case that also serves as one battery terminal having an opening at one end, and the stacked negative electrode plate and positive electrode plate are housed and fixed. It is composed of a chassis housed inside, an upper lid integrally attached to one end of the chassis, and the other battery terminal electrically insulated from the upper lid. Therefore, the upper lid integrally attached to one end side of the chassis is reliably positioned and fixed by housing the chassis in the rectangular case. Then, when the edge portion of the upper lid is welded to the opening edge portion of the rectangular case, the upper lid does not move, and welding failure due to the positional displacement of the upper lid is prevented in advance.

[0015] In a second aspect of the present invention,
The chassis has an open portion into which the laminated negative electrode plate and the positive electrode plate are inserted, a bending piece that is bent to close the open portion and press-fixes the negative electrode plate and the positive electrode plate, and the inserted negative electrode plate. And an opening provided on the lower surface side of the upper lid so that one end side of the positive electrode plate is exposed. Therefore, the negative electrode plate and the positive electrode plate are easily inserted while positioning them in the chassis from the opening portion while alternately stacking them through the separators, and by bending the bending piece so as to close the opening portion, the positioning state is improved. Secured and fixed in the chassis. Therefore, even if the thickness of the laminated electrode plates is thin and the number of laminated electrode plates is large, the laminated negative electrode plate and positive electrode plate can be easily housed and fixed in the chassis without displacement. The stacked negative electrode plate and positive electrode plate can be smoothly stored in the battery case by ensuring the positioning by housing the chassis in the rectangular case. Furthermore, the stacked negative electrode plate and positive electrode plate are assembled and electrically connected to the positive electrode terminal or the chassis through the lead plate while being housed and fixed in the chassis and through the openings provided in the chassis. To be done.

In the third invention of the present invention,
A chassis main body having an opening portion in which the negative electrode plate and the positive electrode plate are stacked, and an opening portion provided in the lower surface side of the upper lid so that one end sides of the inserted negative electrode plate and the positive electrode plate are exposed; , A chassis lid attached to the chassis body so as to close the opening, and pressingly fixing the negative electrode plate and the positive electrode plate between the chassis body. Therefore,
The negative electrode plate and the positive electrode plate are easily inserted while being positioned in the chassis main body from the open portion and alternately stacked via the separators, and the chassis lid is attached to the chassis main body so as to close the open portion. The positioning state is ensured and is pressed and fixed between the chassis body and the chassis lid. Therefore, even if the thickness of the laminated electrode plates is thin and the number of laminated electrode plates is large, the laminated negative electrode plate and positive electrode plate can be easily housed and fixed in the chassis without displacement. The stacked negative electrode plate and positive electrode plate can be smoothly stored in the battery case by ensuring the positioning by housing the chassis in the rectangular case. Further, the stacked negative electrode plate and positive electrode plate are assembled and fixed through the opening provided in the chassis body while being housed and fixed in the chassis, and electrically connected to the positive electrode terminal or the chassis through the lead plate. Connected.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. Example 1. FIG. 1 is an external view showing a state where a chassis of a rectangular lithium secondary battery according to a first embodiment of the present invention is housed in an electrode group. FIG. 1A is a front view thereof, and FIG.
1A shows a direction A oblique view of FIG. 1A, and FIG. 1C shows a direction B oblique view of FIG. 1A. In the figure, the same or corresponding parts as those of the conventional prismatic battery shown in FIGS. 9 to 11 are designated by the same reference numerals, and the description thereof will be omitted.
In the figure, reference numeral 20 denotes a chassis in which a plurality of positive electrode plates 10 and negative electrode plates 14 alternately stacked with a separator interposed therebetween are housed and fixed, and 21 denotes an upper lid integrally attached to one end of the chassis 20. The upper lid 21 is provided with a positive electrode terminal 3 as a battery terminal, which is electrically insulated by a glass hermetic seal 22.

Here, the structure of the chassis 20 is shown in FIG.
Will be described with reference to. An upper lid 21 is attached to one end of the chassis 20 by laser welding, for example, and is integrally attached to the chassis 20, and an opening 20c is provided on the lower surface side of the upper lid 21. Further, the positive electrode plate 10 and the negative electrode plate 14 are provided on one surface thereof.
An opening 20b for inserting the opening is provided, and bending pieces 20a are provided on three sides surrounding the opening 20b. Then, each of the bent pieces 20a is laminated so that the positive electrode plate 10 and the negative electrode plate 14 are alternately inserted through the separator and then bent so as to close the opening 20c from the bending line 20d. The negative electrode plate 10 and the negative electrode plate 14 are pressed and fixed to the back portion of the chassis 20.

FIG. 3 is a perspective view showing a prismatic case of the prismatic lithium secondary battery according to Embodiment 1 of the present invention. In the figure, reference numeral 23 is a prismatic case having an opening at one end. The rectangular case 23 also serves as a negative electrode terminal as a battery terminal, and constitutes a battery case together with the upper lid 21.

In order to assemble the prismatic lithium secondary battery having the above-mentioned structure, first, the positive electrode plate 10, the negative electrode plate 14 and the separator are positioned in the chassis 20 through the opening 20b, and a predetermined number of them are inserted while alternately stacking them. To do.
Then, each of the bending pieces 20a is connected to the bending line 20.
The opening 20b is bent from the position of d so as to close the opening. Therefore, the electrode group of the positive electrode plate 10 and the negative electrode plate 14 laminated by a predetermined number of sheets with the separator interposed therebetween is provided with the bent piece 20a.
It is pressed and fixed by and is stored in the chassis 20 while ensuring the positioned state. At this time, one end side of the electrode group of the positive electrode plate 10 and the negative electrode plate 14, that is, the current collecting ear side is exposed to the outside through the opening 20c. Then, the positive electrode current collecting ears 13 of all the positive electrode plates 10 are overlapped and one end of the positive electrode lead plate 5 is ultrasonically welded, and the other end of the positive electrode lead plate 5 is ultrasonically welded to the positive electrode terminal 3, As shown in FIG. 1, the positive electrode plate 10 is electrically assembled and connected to the positive electrode terminal 3. Further, the negative electrode current collecting ears 17 of all the negative electrode plates 14 are overlapped and one end of the negative electrode lead plate 8 is ultrasonically welded, and the other end of the negative electrode lead plate 8 is ultrasonically welded to the inner back portion of the chassis 20. As shown in FIG. 1, the negative electrode plate 14 is electrically assembled and connected to the chassis 20.

Next, the chassis 20 is inserted into the rectangular case 23 through the opening. Here, by configuring the outer diameter dimension of the chassis 20 to be slightly smaller than the inner diameter dimension of the rectangular case 23, the chassis 20 is guided by the rectangular case 23 and smoothly inserted, and rattling after insertion is suppressed. It is reliably positioned and stored in the rectangular case 23.
Further, by configuring the height dimension of the chassis 20 to match the depth dimension of the rectangular case 23, the upper lid 21 closes the opening at the same surface position as the opening edge of the rectangular case 23. Is located in. Therefore, the edge portion of the upper lid 21 and the opening edge portion of the rectangular case 23 are laser-welded, and as shown in FIG. 4, the upper lid 21 and the rectangular case 23 are hermetically sealed by the laser-welded portion 24. A prismatic lithium secondary battery is obtained in which the positive electrode plate 10 and the negative electrode plate 14 that are stacked in the battery case are stored. The negative electrode plate 14 is electrically connected via a chassis 20 and an upper lid 21 to a rectangular case 23 that also serves as a negative electrode terminal. In addition, the separator is filled with an organic electrolytic solution.

In this way, the prismatic lithium secondary battery is
When 00 pieces were assembled and the number of occurrence of internal short circuit, the number of occurrence of electrode position deviation and the number of defective top lid welding were examined, as shown in Table 1, no internal short circuit, deviation of electrode position and defective welding of top lid were confirmed.

As described above, according to the first embodiment, the chassis 20 includes the open portion 20b into which the positive electrode plate 10 and the negative electrode plate 14 are inserted, and the bent piece 20a which is bent so as to close the open portion 20b. Therefore, the positive electrode plate 10 and the negative electrode plate 14 can be easily inserted into the chassis 20 while positioning the positive electrode plate 10 and the negative electrode plate 14 from the open portion 20b, and then the bending piece 20a is bent to position the positive electrode plate 10 and the negative electrode plate 14 in a positioned state. It can be easily secured and pressed. As a result, there is no displacement or bending of the electrodes,
It is possible to prevent an internal short circuit that occurs due to displacement or bending of the electrodes, and to obtain a prismatic lithium secondary battery with excellent safety that does not cause an ignition or burst accident due to the occurrence of the internal short circuit. Further, since the chassis 20 has the opening 20c on the lower surface side of the upper lid 21, the stacked positive electrode plates 1
0 and one end side of the electrode group of the negative electrode plate 14, that is, the current collecting ear side is exposed to the outside through the opening 20c. Therefore, the respective electrode groups of the positive electrode plate 10 and the negative electrode plate 14 can be connected to the positive electrode terminal 3 and the inner back portion of the chassis 20 through the opening 20c, and the stacked positive electrode plates 10 can be connected.
Also, since the negative electrode plate 14 is housed and fixed in the chassis 20 and does not move, the connecting work can be easily performed, and the assemblability of the battery can be improved. Further, since the upper lid 21 is integrally attached to one end side of the chassis 20, the upper lid 21 is positioned by inserting the chassis 20 into the rectangular case 23. Therefore, when laser welding the edge portion of the upper lid 21 and the opening edge portion of the rectangular case 23, the upper lid 21 is reliably positioned without moving, and the welding between the upper lid 21 and the rectangular case 23 is surely stabilized. It is possible to improve the yield of the battery without defective welding of the upper lid.

Example 2. In the first embodiment, the chassis 2
Bending pieces 20a are respectively provided on three sides surrounding the open portion 20b of 0, and the electrode groups of the stacked positive electrode plate 10 and negative electrode plate 14 are inserted into the chassis 20 through the opening portions 20b, and then the bending pieces 20a are formed. Open part 20b
The electrode group is pressed and fixed by bending so as to close the hole. However, in the second embodiment, as shown in FIG.
The bent piece 20a is provided only on the bottom side of the chassis 20, and the stacked electrode group of the positive electrode plate 10 and the negative electrode plate 14 is inserted into the chassis 20 from the open portion 20b, and then one bent piece 20a is opened. The electrode group is pressed and fixed by bending so as to close the plug, and the same effect is obtained.

Here, 100 prismatic lithium secondary batteries according to the second embodiment were assembled, and the number of occurrences of internal short circuit, the number of occurrence of electrode position deviation, and the number of welding defects of the upper lid were examined, and as shown in Table 1, As in the case of Example 1, no internal short circuit, electrode position shift, or top lid welding failure was confirmed.

Example 3. In the first embodiment, the chassis 2
Bending pieces 20a are respectively provided on three sides surrounding the open portion 20b of 0, and the electrode groups of the stacked positive electrode plate 10 and negative electrode plate 14 are inserted into the chassis 20 through the opening portions 20b, and then the bending pieces 20a are formed. Open part 20b
The electrode group is bent by pressing so as to close the electrode group, but in the third embodiment, as shown in FIG.
The bending piece 20a is provided only on one side of the chassis 20, and the electrode group of the stacked positive electrode plate 10 and negative electrode plate 14 is inserted into the chassis 20 from the opening portion 20b, and then one bending piece 20a is opened. The electrode group is bent so as to close 20b so as to press and fix the electrode group, and the same effect is obtained.

Here, 100 prismatic lithium secondary batteries according to the third embodiment were assembled, and the number of occurrences of internal short circuit, the number of occurrence of electrode position deviation, and the number of top cover welding defects were examined, and as shown in Table 1, As in the case of Example 1, no internal short circuit, electrode position shift, or top lid welding failure was confirmed.

Example 4. FIG. 7 is a perspective view showing a chassis used in a prismatic lithium secondary battery according to Embodiment 4 of the present invention. In the fourth embodiment, the chassis 30 has the upper lid 21 integrally attached to one end side thereof, the opening 31a provided on the lower surface side of the upper lid 21, and the opening 31b provided on the front surface side of the chassis body 31. And a chassis lid 32 having a U-shaped cross section. Then, the positive electrode plate 10, the negative electrode plate 14, and the separator are positioned in the chassis body 31 from the opening portion 31b, and a predetermined number of sheets are inserted while alternately superimposing them, and then the chassis lid 32 is inserted so as to close the opening portion 31b. 31, the chassis lid 32 is laser-welded to the chassis body 31, and the electrode group of the positive electrode plate 10 and the negative electrode plate 14 is connected to the chassis 3 by the laser welding.
It is stored and fixed in 0. The other configurations are the same as those in the first embodiment.

According to the fourth embodiment, the positive electrode plate 10, the negative electrode plate 14, and the separator are positioned in the chassis body 31 from the opening portion 31b, and a predetermined number of sheets can be inserted while alternately stacking the opening portion 31b. By attaching the chassis lid 32 to the chassis body 31 as described above, the electrode group of the positive electrode plate 10 and the negative electrode plate 14 is pressed between the chassis body 31 and the chassis lid 32 to secure the position of the electrode group. While being accommodated, it can be housed and fixed in the chassis 30. Further, the collector ear side of the electrode group housed and fixed from the opening 31a provided on the lower surface side of the upper lid 21 is exposed to the outside, and the connection work between the collector ear and the battery terminal can be performed from the opening 31a. You can do it. Further, since the upper lid 21 is integrally attached to one end side of the chassis body 31, the upper lid 21 can be reliably positioned by inserting the chassis 30 into the rectangular case 23. Therefore, also in the fourth embodiment, the same effect as that of the first embodiment can be obtained.

Here, 100 prismatic lithium secondary batteries according to Example 4 were assembled, and the number of occurrences of internal short circuits, the number of occurrences of electrode position deviations, and the number of top lid welding defects were examined, and as shown in Table 1, As in the case of Example 1, no internal short circuit, electrode position shift, or top lid welding failure was confirmed.

Example 5. In the fourth embodiment, the open portion 31b is provided on the front side of the chassis body 31, but in the fifth embodiment, the open portion 31b is provided on the bottom side of the chassis body 31, as shown in FIG. The same effect as that of the fourth embodiment is obtained. In this case, the positive electrode plate 10
The electrode group of the negative electrode plate 14 is inserted into the chassis body 31, and the chassis lid 32 is inserted from the lower end side of the chassis body 31.
Is fitted until it touches. And the chassis lid 32
Is bent inward and the electrode group is fixed to the chassis lid 32. Further, the chassis body 31 and the chassis lid 32 are laser-welded and integrated, and the electrode group is housed and fixed in the chassis 30.

Here, 100 prismatic lithium secondary batteries according to Example 5 were assembled, and the number of occurrences of internal short circuits, the number of electrode position deviations, and the number of top lid welding defects were examined, and as shown in Table 1, As in the case of Example 1, no internal short circuit, electrode position shift, or top lid welding failure was confirmed.

Comparative Example. In this comparative example, an upper lid provided with the positive electrode terminal 3 electrically insulated by a glass hermetic seal 22 and a rectangular case 23 having an opening at one end are prepared. First, the positive electrode plate 10 and the negative electrode plate 14 are provided. A plurality of sheets are alternately laminated via the separator and inserted into the rectangular case 23. Then, the positive electrode current collecting ears 13 of the plurality of positive electrode plates 10 are assembled and electrically connected to the positive electrode terminal 3 via the positive electrode lead plate 5, and the negative electrode current collectors of the plurality of negative electrode plates 14 are collected. The ear pieces 17 are assembled and electrically connected to the inner wall surface of the rectangular case 23 via the negative electrode lead plate 8. Further, the upper lid was fitted in the opening of the rectangular case 23, laser-welded and hermetically integrated to assemble a rectangular lithium secondary battery. In this way, 100 prismatic lithium secondary batteries according to the comparative example were assembled, and the results of examining the number of occurrence of internal short circuit, the number of occurrence of electrode position shift, and the number of welding defects of upper lid are shown in Table 1. As shown in Table 1, in each of the above-described examples, the number of occurrences of internal short circuit, the number of occurrence of electrode position shift, and the number of top cover welding defects were not confirmed, but in this comparative example, internal short circuit was 4/100 and electrode position shift was found. 12/100 occurred, and top lid welding failure occurred 9/100.

This is because, in the comparative example, since a large number of thin electrode groups are directly inserted into the rectangular case 23 from the openings, it is difficult to insert the electrode groups, and at that time, the electrodes are bent or misaligned. Is likely to occur, which may cause an internal short circuit. Moreover, since the upper lid is supported from below by the thin current collecting ears, it is considered that the upper lid is not firmly supported and the positioning of the upper lid during welding becomes unstable, resulting in poor welding. On the other hand, in each of the above-described embodiments, the electrode group of the positive electrode plate 10 and the negative electrode plate 14 is connected to the chassis 20 from the opening 20b (31b).
(Or the chassis body 31) is positioned and inserted, and is fixed while being secured by the bent piece 20a (or the chassis lid 32).
No bending or misalignment of the electrodes occurs during assembly into the chassis 20 (30). Moreover, the electrode group is the chassis 2
Since it is housed in the rectangular case 23 in a state of being housed and fixed at 0 (30), the electrode is not bent or displaced during assembly in the rectangular case 23. Therefore, an internal short circuit due to bending or displacement of the electrodes does not occur. Also,
The upper lid 21 is the chassis 20 (or chassis body 31)
Since the chassis 20 is housed in the rectangular case 23, the upper lid 21 is reliably positioned, welding can be stably performed, and welding defects do not occur.

[0035]

[Table 1]

In each of the above embodiments, the positive and negative electrode current collecting ears 13, 13 are provided on the upper ends of the positive and negative electrode plates 10 and 14, respectively.
Although 17 are provided and are assembled at the upper part of the electrode group and connected to the battery terminal, the shape, position and connection method of the current collecting ear are not limited to this.

Further, in each of the above-mentioned embodiments, the prismatic lithium secondary battery using the organic electrolytic solution is described. However, the present invention is applicable to prismatic batteries of other systems in which a large number of electrodes are laminated and used. It goes without saying that it can be applied.

[0038]

Since the present invention is constructed as described above, it has the following effects.

According to the first aspect of the present invention, the battery case has a rectangular case which also serves as one battery terminal having an opening at one end, and the stacked negative electrode plate and positive electrode plate are housed and fixed. Consists of a chassis housed in the case, an upper lid integrally attached to one end of the chassis, and the other battery terminal electrically insulated from the upper lid and housed in the rectangular case. The edge of the upper lid integrated with the chassis and the edge of the opening of the rectangular case are welded and hermetically integrated, and one electrode plate group of the stacked negative electrode plate and positive electrode plate is connected via the lead plate. Since the other electrode plate group of the laminated negative electrode plate and positive electrode plate is electrically assembled via the lead plate and connected to the other battery terminal, By storing the chassis in a rectangular case The lid can be reliably positioned, welding of the upper lid and the square case can stably upper lid welding occurrences of poor suppressed thereby improving the yield of the battery.

According to a second aspect of the present invention, in the first aspect, the chassis closes the open portion into which the stacked negative electrode plate and positive electrode plate are inserted and the open portion. Since it is provided with a bending piece for bending the negative electrode plate and the positive electrode plate to fix the negative electrode plate and the positive electrode plate, and an opening provided on the lower surface side of the upper lid so that one end side of the inserted negative plate plate and the positive electrode plate are exposed. In addition to the effect of the first invention, the negative electrode plate and the positive electrode plate can be easily positioned and housed and fixed in the chassis, and the bending and displacement of the electrodes can be prevented. Therefore, an internal short circuit caused by bending or displacement of the electrodes can be prevented in advance, and ignition and rupture due to the internal short circuit can be prevented, and a highly safe prismatic battery can be obtained. Further, the work of connecting the electrode group and the battery terminal can be performed through the opening, and the assemblability of the battery can be improved.

According to a third aspect of the present invention, in the first aspect of the invention, the chassis has an opening for inserting the laminated negative electrode plate and positive electrode plate, and the inserted negative electrode plate and positive electrode plate. And a chassis main body having an opening provided on the lower surface side of the upper lid so that one end side of the chassis is exposed, and a negative electrode plate and a positive electrode plate mounted between the chassis main body and closing the opening. Since it has a chassis lid that is pressed and fixed to, the same effect as the second aspect of the invention can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a state where a chassis of an prismatic lithium secondary battery according to a first embodiment of the present invention is housed in an electrode group.

FIG. 2 is a perspective view showing a chassis used for the prismatic lithium secondary battery according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a rectangular case used in the rectangular lithium secondary battery according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a prismatic lithium secondary battery according to Embodiment 1 of the present invention.

FIG. 5 is a perspective view showing a chassis used in a prismatic lithium secondary battery according to a second embodiment of the invention.

FIG. 6 is a perspective view showing a chassis used in a prismatic lithium secondary battery according to Embodiment 3 of the invention.

FIG. 7 is a perspective view showing a chassis used in a prismatic lithium secondary battery according to Embodiment 4 of the invention.

FIG. 8 is a perspective view showing a chassis used in a prismatic lithium secondary battery according to Embodiment 5 of the invention.

FIG. 9 is a cross-sectional view showing a conventional rectangular nickel-cadmium battery.

FIG. 10 is a partially cutaway plan view showing a positive electrode plate used in a conventional prismatic lithium secondary battery.

FIG. 11 is a partially cutaway plan view showing a negative electrode plate used in a conventional prismatic lithium secondary battery.

[Explanation of symbols]

3 positive electrode terminal (battery terminal), 5 positive electrode lead plate (lead plate), 8 negative electrode lead plate (lead plate), 10 positive electrode plate,
14 negative electrode plate, 20 chassis, 20a bent piece,
20b open part, 20c open part, 21 upper cover (battery case), 23 rectangular case (battery case), 30 chassis, 31 chassis body, 31a opening part, 31b open part, 32, chassis cover.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoshi Sudo 333 Minorita, Matsudo City, Chiba Toyo Takasago Dry Electric Battery Co., Ltd. Company development department

Claims (3)

[Claims] 1. A prismatic battery in which a plurality of negative electrode plates and positive electrode plates are alternately stacked via a separator and housed in a prismatic battery case, wherein one end of the battery case has an opening. A square case that also serves as a battery terminal, a chassis that accommodates and fixes the stacked negative electrode plate and positive electrode plate and is housed in the rectangular case, and an upper lid integrally attached to one end side of the chassis. And the other battery terminal electrically insulated and provided on the upper lid, and an edge portion of the upper lid integrated with the chassis housed in the rectangular case and an opening edge portion of the rectangular case. Are welded and hermetically integrated, and one electrode plate group of the laminated negative electrode plate and positive electrode plate is electrically assembled via a lead plate, connected to the chassis, and laminated. The other pole of the negative and positive plates The prismatic battery, wherein the plate group is electrically assembled via a lead plate and connected to the other battery terminal. 2. The chassis includes an open portion into which the stacked negative electrode plate and positive electrode plate are inserted, and a bent piece that is bent to close the open portion and press-fixes the negative electrode plate and the positive electrode plate. The prismatic battery according to claim 1, further comprising: an opening portion provided on a lower surface side of the upper lid so that one end sides of the inserted negative plate plate and the positive electrode plate are exposed. 3. The chassis has an opening provided on the lower surface side of the upper lid so that an opening portion into which the stacked negative electrode plate and positive electrode plate are inserted and one end side of the inserted negative electrode plate and positive electrode plate are exposed. A chassis main body having a portion, and a chassis lid attached to the chassis main body so as to close the opening and pressingly fixing the negative electrode plate and the positive electrode plate between the chassis main body. The prismatic battery according to claim 1.