JP2007066599A - Storage battery and battery pack - Google Patents

Abstract

An object of the present invention is to solve the problem that the contact resistance between a sealing plate and a current collector is increased, and to provide a storage battery having a small contact resistance and excellent in large current discharge characteristics.
An electrode plate group consisting of a strip-like positive electrode plate, a negative electrode plate, and a separator and an electrolyte solution are housed inside, and a current collector connected to one electrode plate of the electrode plate group. A metal bottomed case 9 connected to 8, and a seal connected to the current collector 7 connected to the other plate of the electrode plate group 6 while sealing the opening of the metal bottomed case 9 It is a storage battery provided with the board 11, Comprising: The said metal bottomed case 9 has the collar part 10 which protrudes outward in the said opening part, and the said sealing plate 11 mounted in this collar part 10 is a collar part. The storage battery is sealed at the bent portion of the peripheral edge of the ten.
[Selection] Figure 1

Description

  The present invention relates to a storage battery including a spiral electrode group, and more particularly to a storage battery and a battery pack used as a driving power source for a vehicle.

  Alkaline storage batteries represented by nickel-cadmium storage batteries and nickel-hydrogen storage batteries are widely used in various applications such as mobile phones and laptop computers because they are reliable and easy to maintain. In recent years, there has been a demand for the development of an alkaline storage battery suitable for large current discharge as a power source for power tools, power-assisted bicycles and electric vehicles.

  The alkaline storage battery is formed by spirally winding a strip-shaped positive electrode plate and a negative electrode plate through a separator to form a group of electrode plates, housed in a metal bottomed case together with the electrolyte, and sealed. The

  In such an alkaline storage battery, a gasket made of a polymer resin is arranged inside the opening portion of the bottomed case made of metal, and the gasket is compressed by applying a force from the outside to the opening portion, and the repulsive force is used for the metal. The opening of the bottomed case is sealed and sealed.

  Furthermore, in alkaline storage batteries used for large current discharge applications, the positive electrode plate and the negative electrode plate are wound so that the upper end or lower end of the positive electrode plate protrudes from the upper and lower sides of the electrode plate group, and the positive electrode plate and the negative electrode plate protrude from the upper and lower ends. Although the current collector is connected to the portion at a plurality of locations to improve the current collecting performance from the electrode plate, there is a problem that the contact resistance increases particularly in the lead terminal connecting the sealing plate and the current collector.

Therefore, a method of directly welding the sealing plate and the current collector without using a lead terminal has been proposed. (For example, refer to Patent Document 1.)
JP 2001-256994 A

  However, in the above conventional configuration, in the process of welding the sealing plate and the current collector, the receiving mold supporting the battery is set at the bottom of the battery, so the height of the welding electrode is not stable, and as a result, it is reliable and stable. There was a possibility that welding could not be performed and the contact resistance increased.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a storage battery having low contact resistance and excellent large current discharge characteristics.

  In order to solve the above-described problems, the storage battery of the present invention stores therein a current collector made of a flat plate connected to one of a group of electrode plates made of a strip-like positive electrode plate, a negative electrode plate, and a separator, and an electrolyte. A storage battery comprising a metal bottomed case and a sealing plate that seals the opening of the metal bottomed case, wherein the metal bottomed case has a flange protruding outward from the opening. And the sealing plate placed on the flange is sealed at the bent portion of the peripheral edge of the flange, and the current collector and the sealing plate are electrically connected. .

  According to the present invention, since the sealing plate and the current collector can be welded using the flange portion of the metal bottomed case, the contact resistance between the sealing plate and the current collector is reduced, and the storage battery having excellent large current discharge characteristics. Is obtained.

In the embodiment of the present invention, an electrode plate group composed of a strip-like positive electrode plate, a negative electrode plate and a separator and an electrolytic solution are housed inside, and connected to a current collector connected to one electrode plate of the electrode plate group. A storage battery comprising a bottomed metal case and a sealing plate for sealing an opening of the bottomed metal case and connected to a current collector connected to the other electrode plate of the electrode plate group There,
The metal bottomed case has a flange projecting outward at the opening, and the sealing plate placed on the flange is sealed by a bent portion at the peripheral edge of the collar. .

  According to this configuration, in the process of welding the sealing plate and the current collector, the receiving mold that supports the battery can be set to the buttocks of the battery, so that variations in the height of the welding electrode can be suppressed, and the applied pressure during welding can be reduced. It can be stabilized. As a result, the contact resistance between the sealing plate and the welded portion of the current collector is reduced, and a storage battery having excellent large current discharge characteristics can be obtained. Since the welding load is received at the buttock, unlike the conventional method with a metal bottom case, the metal bottom case can be prevented from being scratched or dented, and the metal bottom case can be made thinner. Also play.

  In the assembly battery transport process, the chuck can be transported using the collar, so there is no risk of the battery falling, and problems such as deformation of the side surface of the metal bottomed case are eliminated, enabling stable transport at high speed. There is an effect that can be done.

  In the step of discriminating the vertical direction of the battery, it can be easily discriminated using the step between the cylindrical portion and the collar portion of the metal bottomed case. The conventional method of detecting a slight level difference between the positive electrode cap of the sealing plate and the metal bottomed case has many false detections, and the contact type detection method may cause an external short between the positive electrode cap and the negative electrode of the metal bottomed case. However, these problems can be solved.

  Moreover, it is preferable that the outer diameter dimension of the sealing board of this invention is 98 to 120% of the cylindrical part outer diameter dimension of a metal bottomed case.

  If it does in this way, it will be easy to caulk at the time of sealing with the bending part of the peripheral part of a collar part, and since it can compress strongly, liquid-proof nature can be improved. Furthermore, there is an effect of stabilizing the positioning of the sealing plate when welding the sealing plate and the current collector.

  In another embodiment of the present invention, a current collector made of a flat plate connected to one of a group of electrode plates made of a strip-like positive electrode plate, a negative electrode plate, and a separator, and a metal that contains an electrolyte therein A battery pack comprising a plurality of storage batteries that are electrically connected in series with a bottomed case and a sealing plate that seals an upper portion of the metal bottomed case, wherein the metal bottomed case has an opening. The sealing plate is placed on the receiving portion, the sealing plate is placed on the receiving portion, the opening portion is bent inward and caulked to seal the current collector and the sealing plate. A plurality of electrically connected storage batteries were electrically connected in series.

  According to this configuration, when the connection ring for connecting the batteries is welded to the upper part of the battery, the receiving mold for supporting the battery is formed in the same manner as in the process of welding the sealing plate and the current collector. Since it can set to a part, the height dispersion | variation of a welding electrode can be suppressed and the applied pressure at the time of welding can be stabilized.

  In addition, when welding a plurality of batteries in series with the bus bar, the side surface of the battery can be supported by the flange, so that the support of the side surface of the battery does not slip when the electrode is pressed, and the welding point does not shift. As a result, there is an effect that the weldability between the batteries and between the battery and the bus bar is stabilized.

  Moreover, since it has a collar part, the heat radiation space of a battery is made in the collar part lower part of a battery side surface. There is also an effect that a heat dissipation space can be easily secured without requiring a separate component for holding the heat dissipation space.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  In addition, the figure shown here is an example, Comprising: If it has the structure represented to the claim of this invention, the same effect can be acquired.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of the storage battery of the present invention, and FIG. 2 is an explanatory view showing a welding process of the sealing plate and current collector of the storage battery of the present invention.

  The tip portion of the positive electrode plate 1 protrudes upward to provide an exposed positive electrode core portion 3, and the tip portion of the negative electrode plate 2 protrudes downward to provide an exposed negative electrode core portion 4. An electrode plate group 6 is formed by winding these positive and negative electrode plates in a spiral shape with a separator 5 interposed therebetween.

  The upper current collector 7 is welded to the exposed positive electrode core member 3, and the lower current collector 8 is similarly welded to the exposed negative electrode core member 4.

  After these electrode plate groups 6 are inserted into the metal bottomed case 9, the lower current collector 8 and the metal bottomed case 9 are welded.

  The bottomed case 9 made of metal has an eaves portion 10 projecting outward at the opening, and a sealing plate 11 is placed on the eaves portion 10 and the peripheral edge of the eaves portion 10 is bent inward and caulked. Seal.

  The collar portion 10 is supported by a receiving mold 12, and the current collector 7 and the sealing plate 11 are pressurized and welded from above by the welding electrode 13.

  Next, a predetermined amount of alkaline electrolyte is inserted into the bottomed case 9 made of metal, and the positive electrode cap 14 is welded to produce a cylindrical alkaline storage battery.

Example 1
The tip of the positive electrode plate 1 made of sintered nickel having a thickness of 1.0 mm protrudes 1.5 mm upward, and the tip of the negative electrode plate 2 made of paste cadmium having a thickness of 0.7 mm protrudes 1.5 mm downward. Thus, the electrode plate group 6 wound in a spiral shape was formed via the separator 5.

  An upper current collector 7 made of low carbon steel having a thickness of 0.40 mm is welded to the tip portion of the positive electrode plate 1. Similarly, a lower current collector 8 having a thickness of 0.20 mm is welded to the tip portion of the negative electrode plate 2. Welded.

  These electrode plate groups 6 are inserted into a metal bottomed case 9, the metal bottomed case 9 and the lower current collector 8 are connected by welding, and a predetermined amount of alkaline electrolyte is added to the upper current collector 7. Was inserted into the metal bottomed case 9 using the central hole.

  Next, the sealing plate 11 is placed on the flange portion 10 of the bottomed case 9 made of metal, and the flange portion 10 is supported by the receiving mold 12 and pressed by the welding electrode 13 from above to connect the current collector 7 and the sealing plate 11. One point was welded. Then, the peripheral part of the collar part 10 was bent inward, and it crimped and sealed, and comprised the cylindrical alkaline storage battery.

The outer diameter of the sealing plate 11 was 120% of the outer diameter of the cylindrical portion of the bottomed case 9 made of metal.

  This cylindrical alkaline storage battery has a diameter of 35.0 mm, a height of 56.5 mm, and a nominal capacity of 5000 mAh.

  Further, a nickel material may be used as the material of the upper current collector 7. If a nickel material is used as the material, it is possible to obtain an effect excellent in workability such as that burrs are hardly generated.

(Example 2)
A cylindrical alkaline storage battery configured in the same manner as in Example 1 except that the upper current collector 7 and the sealing plate 11 were welded at two points was referred to as Example 2.

(Example 3)
A cylindrical alkaline storage battery configured in the same manner as in Example 1 except that the upper current collector 7 and the sealing plate 11 were welded at four points was referred to as Example 3.

Example 4
A cylindrical alkaline storage battery having the same configuration as in Example 1 was used in Example 4 except that the outer diameter of the sealing plate 11 was set to 100% of the outer diameter of the cylindrical portion of the bottomed case 9 made of metal.

(Example 5)
A cylindrical alkaline storage battery configured in the same manner as in Example 4 except that the upper current collector 7 and the sealing plate 11 were welded at two points was used as Example 5.

(Example 6)
A cylindrical alkaline storage battery configured in the same manner as in Example 4 except that the upper current collector 7 and the sealing plate 11 were welded at four points was used as Example 6.

(Example 7)
A cylindrical alkaline storage battery configured in the same manner as in Example 1 was used in Example 7 except that the outer diameter of the sealing plate 11 was set to 98% of the outer diameter of the cylindrical portion of the bottomed case 9 made of metal.

(Example 8)
A cylindrical alkaline storage battery configured in the same manner as in Example 7 except that the upper current collector 7 and the sealing plate 11 were welded at two points was referred to as Example 8.

Example 9
A cylindrical alkaline storage battery configured in the same manner as in Example 7 except that the upper current collector 7 and the sealing plate 11 were welded at four points was used as Example 9.

(Comparative Example 1)
Cylindrical alkali configured in the same manner as in Example 1 except that a metal bottomed case without a flange is used and the outer diameter of the sealing plate is 90% of the outer diameter of the cylindrical part of the metal bottomed case. The storage battery was referred to as Comparative Example 1.

(Comparative Example 2)
Comparative Example 2 was a cylindrical alkaline storage battery configured in the same manner as Comparative Example 1 except that the upper current collector and the sealing plate were welded at two points.

(Comparative Example 3)
A cylindrical alkaline storage battery configured in the same manner as in Comparative Example 1 was used as Comparative Example 3 except that the upper current collector and the sealing plate were welded at four points.

(Comparative Example 4)
A cylindrical alkaline storage battery configured in the same manner as in Example 1 was used as Comparative Example 4 except that the outer diameter of the sealing plate was 97% of the outer diameter of the cylindrical portion of the metal bottomed case.

The characteristics of the alkaline storage battery configured as described above will be described below.
Table 1 shows the results of comparing the connectivity between the sealing plate of the cylindrical alkaline storage battery and the upper current collector in this example and the comparative example based on the welding strength and the contact resistance value.

The welding strength was judged based on the size of the fracture mark after the tensile test. A microscope was used to measure the size of the fracture mark, and two directions of the fracture mark in the X direction and the Y direction were measured. The dimension of the fracture mark was calculated as (X-direction dimension + Y-direction dimension) / 2, and the larger the fracture mark dimension, the higher the welding strength, and the ratio when Comparative Example 1 was 100% was shown. The average value was shown when there were multiple welds.

  For the contact resistance value, the sealing plate and the upper current collector were welded, and the contact resistance value of the weld was measured before the alkaline electrolyte was inserted. Since the contact resistance value also varies depending on the battery size and the like as with the welding strength, the contact resistance value is shown as a ratio when the comparative example 1 is 100%.

  As shown in this (Table 1), Examples 1-9 which provided the collar part 10 in the metal bottomed case 9 increased welding strength compared with Comparative Examples 1-3 without a collar part, and contact resistance value. Was confirmed to be small.

  According to Examples 1-9, since the metal bottomed case 9 has the flange 10, in the process of welding the sealing plate 11 and the upper current collector 7, a receiving mold for supporting the battery is used as the battery. Since it can set to the collar part 10, the height dispersion | variation of a welding electrode can be suppressed and the applied pressure at the time of welding can be stabilized. As a result, it can be estimated that the welding strength between the sealing plate 11 and the upper current collector 7 is increased by nearly 20 to 25%, and the contact resistance value is slightly reduced by 15%.

Moreover, it turns out that the ratio of the outer diameter dimension of the sealing plate 11 to the outer diameter dimension of the cylindrical portion of the bottomed case 9 made of metal increases slightly as the weld strength and the contact resistance value increase as 98%, 100%, and 120%. It was. This is because the sealing plate 11 is placed on the flange portion 10 of the bottomed case 9 made of metal, and when the welding plate 13 is pressurized and welded from above, the bending of the sealing plate 11 is reduced and welding is performed in a more stable state. We can guess that it is possible.

  According to Examples 7-9, if it is the structure of this invention which has the collar part 10 in the metal bottomed case 9, the outer diameter dimension of the sealing board 11 will be the cylindrical part outer diameter of the metal bottomed case 9 It was found that the connectivity could be improved even with 98% of the dimensions. If the outer diameter dimension of the sealing plate 11 is 98% of the outer diameter dimension of the cylindrical portion of the metal bottomed case 9, the peripheral edge portion of the sealing plate 11 exists on the plate thickness portion of the metal bottomed case 9. It can be inferred that the applied pressure during welding could be stabilized.

  Moreover, if the outer diameter of the sealing plate 11 was 98 to 120% of the outer diameter of the cylindrical portion of the bottomed case 9 made of metal, it was confirmed that the leakage resistance could be improved in the heat shock test.

  If it does in this way, it can be estimated that the caulking at the time of sealing with the bent part of the peripheral part of the collar part 10 is easy, and since it can compress strongly, sealing hermeticity improves and, as a result, liquid-proof property improved. .

  In addition, if the outer diameter of the sealing plate is larger than 120% of the outer diameter of the cylindrical portion of the metal bottomed case, the upper limit is 120% because there is no commercial value, for example, the space efficiency at the time of battery pack configuration is not good. preferable.

  It was also found that the welding strength and contact resistance can be improved by increasing the number of welding points to 1, 2, 4, and so on. As described above, the welding strength uses the size of the welding mark as an index. By increasing the number of welding points, such as 2 points and 4 points, and pressurizing at multiple points, the sealing plate 11 and the upper current collector at the time of welding and pressurization are used. 7 is improved, and as a result, it can be inferred that the dimension of the weld mark is stable.

  If the number of welding points is increased, the connectivity can be improved. For example, it can be presumed that a highly reliable cylindrical alkaline storage battery is obtained in which the contact resistance value does not increase even with vibration during long-term use.

  On the other hand, the reason why the welding strength of Comparative Examples 1 to 3 is lower than that of each Example and the contact resistance value is increased is that the receiving die is the bottom of the metal bottomed case in the welding process of the sealing plate and the upper current collector. It is caused by having installed in. Since the pressurization of the electrode is received at the bottom of the metal bottomed case, it can be assumed that the variation in battery height and the positioning of the battery become unstable, and as a result, the pressurization during welding becomes unstable.

  The reason why the welding strength of Comparative Example 4 is lower than that of Example 7 and the contact resistance value is slightly larger is that the outer diameter of the sealing plate is 97% of the outer diameter of the cylindrical portion of the bottomed case made of metal. If it becomes small, since the peripheral part of a sealing board becomes below the internal-diameter dimension of a metal bottomed case, it can be guessed that it lacked the stability of the applied pressure at the time of welding.

  Next, using the cylindrical alkaline storage batteries of Example 3, Example 5, Example 7, and Comparative Example 1, large current discharge characteristics were compared.

  The evaluation of the large current discharge characteristics was carried out in an atmosphere of 20 ° C., after charging for 15 hours at a charging current of 500 mA, and then discharging at a discharging current of 5 A up to a discharging end voltage of 1.0 V. It was evaluated by a discharge capacity ratio obtained by dividing the discharge capacity at 27A discharge by the discharge capacity at 5A discharge.

  The evaluation results of the large current discharge characteristics were 91.3% for Example 3, 89.5% for Example 5, 87.2% for Example 7, and 84.1% for Comparative Example 2.

  In Examples 3, 5, and 7, the weld resistance between the sealing plate and the upper current collector was improved and the contact resistance value was reduced, so that it was confirmed that the large current discharge characteristics were improved as compared with Comparative Example 1. It was done.

  It is useful as a power source for power-assisted bicycles and electric vehicles, including electric tools that require large current discharge.

Schematic sectional view showing an embodiment of the storage battery of the present invention Explanatory drawing which shows the sealing process of the storage battery of this invention, and the welding process of an electrical power collector

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Exposed positive electrode core part 4 Exposed negative electrode core part 5 Separator 6 Electrode board group 7 Upper current collector 8 Lower current collector 9 Metal bottom case 10 Eave part 11 Sealing plate 12 Receiving Type 13 Welding electrode 14 Positive electrode cap

Claims (3)

A metal bottomed case that contains an electrode plate group consisting of a strip-like positive electrode plate, a negative electrode plate, and a separator, and an electrolyte, and is connected to a current collector connected to one electrode plate of the electrode plate group. And a storage battery comprising a sealing plate connected to a current collector connected to the other electrode plate of the electrode plate group while sealing the opening of the metal bottomed case,
The said metal bottomed case has the collar part which protrudes outward in the said opening part, The storage battery which sealed the said sealing plate mounted in this collar part with the bending part of the peripheral part of a collar part.   The storage battery according to claim 1, wherein an outer diameter of the sealing plate is 98 to 120% of an outer diameter of the cylindrical portion of the bottomed case made of metal. A battery pack in which a plurality of the storage batteries according to claim 1 are stored in a pack case.