JPH0553120U - Secondary battery - Google Patents

Abstract

(57) [Summary] [Objective] In a secondary battery in which an electrode unit is sandwiched between opposite side plates of a battery case, its life characteristics are improved and its volume is reduced. [Structure] The battery case 1 is made of a metal plate, and each side plate 19 is
The plate-shaped main body portion 20, the reinforcing portion 21 having a closed structure, which is continuously connected to the main body portion 20 so as to project outward from the outer surface of the main body portion 20, and the electrode which is located inward of the inner surface of the main body portion 20. The holding portion 24 having a closed structure is provided continuously over the entire circumference of the inner wall 23 of the reinforcing portion 21 so as to have the pressing surface 23 that is crimped to the unit U. According to this battery case 1, the active material can be retained and high cooling efficiency can be maintained, and the volume can be reduced by reducing the wall thickness.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a secondary battery, and more particularly to an improvement of a secondary battery in which an electrode unit is sandwiched between opposite side plates of a battery case.

[0002]

[Prior Art]

 Conventionally, in this type of secondary battery, the battery case is made of synthetic resin, and the thickness of the both side plates is formed thick because of the pressure between the electrode units.

[0003]

[Problems to be solved by the device]

 However, if the battery case is configured as described above, the cooling efficiency against the temperature rise during discharge is poor, the life characteristics of the secondary battery is low, and the volume of the battery case increases, so the unit volume of the secondary battery increases. There arises a problem that the energy density per hit decreases.

In view of the above, the present invention has an object to provide the secondary battery capable of increasing the cooling efficiency of the battery case and reducing the volume thereof.

[0005]

[Means for Solving the Problems]

 The present invention relates to a secondary battery in which an electrode unit is sandwiched between opposite side plates of a battery case, the battery case is made of a metal plate, and each side plate has a flat plate-shaped main body and an inner surface of the main body. It is characterized in that it is provided with a holding portion of a closed structure which is connected to the main body portion so as to have a pressing surface which is located more inward than the main body and is pressed against the electrode unit.

[0006]

【Example】

 FIG. 1 shows a secondary battery B, and an electrode unit U 1 shown in FIGS. 2 to 4 is housed in the battery case 1. The electrode unit U includes an anode plate group 2 and a cathode plate group 3. The anode plate group 2 is composed of a plurality of anode plates 4 and the cathode plate group 3 is composed of a plurality of cathode plates 5 tightened by bolts 6 and 7 and nuts 8 and 9, respectively. The anode plate 4 and the cathode plate 5 are alternately superposed with the microporous separator 10 interposed therebetween, and the cathode plates 5 are arranged on both outermost sides. The number of the anode plates 4 and the cathode plates 5, and thus the number of electrode plates used is about 10 to 14, but in FIG. 3, the number of electrode plates used is smaller than that of the actual electrode unit U for convenience. It is drawn.

The anode plate 4 is composed of a Ni-based current collector 11 and a Ni-based active material assembly 12 held by the current collector 11, and a bolt insertion hole 14 is formed in a protrusion 13 of the current collector 11. It is formed. The protrusion 13 of one current collector 11 is longer than the others, and the long protrusion 13 is connected to the anode terminal T ₁ .

The separator 10 is made of an electrically insulating material such as polyethylene or polypropylene.

The cathode plate 5 includes a Ni-based current collector 15 and an active material assembly 16 held by the current collector 15, and a bolt insertion hole 18 is formed in a protrusion 17 of the current collector 15. It The protrusion 17 of one current collector 15 is longer than the other, and the long protrusion 17 is connected to the cathode terminal T ₂ .

In the cathode plate 5, the active material is hydrogen absorbing / desorbing metal powder (hereinafter referred to as MH powder). The MH powder, for _{example, MmAl 0.3 Mn 0.4 Co 0.5 Ni} 3. 8 (Mm is misch metal, numerical atomic ratio) is found using those having a composition such.

The electrode unit U is forcibly inserted between the opposite side plates 19 of the battery case 1 with the side plates 1a and the positive and negative plates 4 and 5 in parallel.

As shown in FIGS. 1 and 2, the battery case 1 is made of a metal plate, for example, a stainless steel plate (JIS SUS304 material) having a thickness of 0.5 mm. Each side plate 19 is a press-molded product, and is composed of a flat plate-shaped main body 20 and a closed-section channel-shaped reinforcement portion continuously connected to the main body 20 so as to project outward from the outer surface of the main body 20. 21 and a pressing portion 24 having a closed structure, which is continuously provided over the entire inner wall 23 of the reinforcing portion 21 so as to have a pressing surface 22 that is located inward of the inner surface of the main body portion 20 and is crimped to the electrode unit U. It has and.

The reinforcing portion 21 has a substantially cocoon shape in which each end of the two arc-shaped portions 21a is connected by a pair of parallel portions 21b, and the pressing portion 24 is positioned so as to be located at the substantially center of each arc-shaped portion 21a. In addition, a bottomed cylindrical projection 25 that opens to the pressing surface 22 is provided.

When the battery case 1 is configured as described above, the expansion and contraction of the electrode unit U due to charging and discharging is absorbed by the elastic deformation of the reinforcing portion 21 of each side plate 19, whereby the electrode unit U is held by the side plates 19. It is possible to prevent the active material from dropping off on the positive and negative plates 4 and 5 by constantly and firmly pinching by the portion 24.

Further, since the heat dissipation of the battery case 1 is good, the cooling efficiency against the temperature rise at the time of discharging can be enhanced, and thereby the charging efficiency can be enhanced.

By thus retaining the active material and maintaining the high cooling efficiency, the life characteristics of the secondary battery B can be improved.

Even if the battery case 1 is made thin, its strength can be ensured by the reinforcing portion 21 and the pressing portion 24. Therefore, the volume of the battery case 1 can be reduced and the unit of the secondary battery B can be reduced. The energy density per volume can be improved.

In addition to the reinforcing function of the holding portion 24, the bottomed cylindrical projection 25 provided on the holding portion 24 temporarily retains hydrogen due to the absorption and desorption of hydrogen by the MH powder to oxidize the MH powder. It also has the function of suppressing

FIG. 5 shows the relationship between the charge / discharge frequency and the discharge capacity in the secondary battery B according to the present invention and the conventional example. In the figure, the line x corresponds to the present invention, and the line y corresponds to the conventional example.

The charging / discharging conditions are as follows. Charge: 2.5 A, 15 hours (150% charge); Discharge: 5.0 A, 1.0 V vs Ag / AgCl (reference electrode) cut off; Electrolyte: 6N-KOH, liquid temperature 25 ° C.

As is clear from comparison between the lines x and y in FIG. 5, in the case of the present invention shown by the line x, the discharge capacity hardly changes even after 150 times of charge / discharge, but the line y shows. In the case of the conventional example, the discharge capacity drops sharply after the number of charge / discharge cycles is about 100 times.

Further, when the ratio of the discharge capacity to the initial capacity was obtained when the number of charge / discharge cycles was 75, it was about 98% in the case of the present invention, but was about 80% in the case of the conventional example.

From these results, it can be seen that the secondary battery according to the present invention has excellent life characteristics as compared with the conventional example.

6 and 7 show another embodiment of the present invention, in which each side plate 19 of the battery case 1 has a reinforcing portion 21 formed in a circular shape. In this case, the same effect as described above can be obtained.

In both of the above-described embodiments, the holding portion 24 is indirectly connected to the main body portion 20 via the reinforcing portion 21, but in the present invention, the reinforcing portion 21 is omitted and the holding portion 24 is provided in the main body portion. Those directly connected to 20 are also included. Also in this case, the effect of reinforcing each side plate 19 can be obtained by the pressing portion 24 having the closed structure.

[0026]

According to the present invention, by constructing the battery case as described above, it is possible to provide a secondary battery having excellent life characteristics and a high energy density per unit volume. .

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a secondary battery.

2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a schematic perspective view of an electrode unit.

FIG. 4 is an exploded perspective view of an electrode unit.

FIG. 5 is a graph showing the relationship between the number of times of charge and discharge and the discharge capacity.

FIG. 6 is a perspective view showing another embodiment of the secondary battery.

7 is a sectional view taken along line 7-7 of FIG.

[Explanation of symbols]

 1 Battery Case 19 Side Plate 20 Main Part 21 Reinforcing Part 22 Clamping Surface 23 Inner Wall 24 Holding Part 25 Bottomed Cylindrical Protrusion B Secondary Battery U Electrode Unit

Claims (3)

[Scope of utility model registration request] 1. A secondary battery in which an electrode unit (U) is sandwiched between opposite side plates (19) of a battery case (1), and the battery case (1) is made of a metal plate. The side plate (19) has a flat plate-shaped main body (20) and a clamping surface (22) which is located inward of the inner surface of the main body (20) and is crimped to the electrode unit (U). A rechargeable battery comprising: a main body (20) and a closed structure pressing portion (24) connected to the main body portion (20). 2. A secondary battery in which the electrode unit (U) is sandwiched between opposite side plates (19) of the battery case (1), the battery case (1) is made of a metal plate, The side plate (19) is a flat plate-shaped main body (20), and a reinforcing member (21) having a closed structure, which is connected to the main body (20) so as to project outward from the outer surface of the main body (20). And an inner wall (23) of the reinforcing portion (21) around the inner wall (23) of the main body (20) so as to have a pressing surface (22) which is located inward of the inner surface of the main body (20) and is crimped to the electrode unit (U). A rechargeable battery, comprising: a pressing portion (24) having a closed structure that is continuously provided across the secondary battery. 3. The pressing surface (2) is attached to the pressing portion (24).
The secondary battery according to claim 1 or 2, wherein a bottomed cylindrical projection (25) opening to 2) is provided.