JP4242953B2 - Manufacturing method of battery pack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a set batteries connected in series by arranging a plurality of unit cells in a row.
[0002]
[Prior art]
Alkaline batteries such as nickel-cadmium batteries and nickel-hydrogen batteries are used for applications such as electric tools and electric vehicles that discharge with a large current. In these applications, since high output is required, a plurality of single cells are connected in series and used in the form of an assembled battery.
[0003]
As shown in FIG. 1, the assembled battery is manufactured by connecting a plurality of unit cells 1 in series via a lead plate 2. As shown in FIG. 2, the lead plate 2 has one end welded to the positive electrode cap 4 provided as a positive electrode terminal on the battery sealing plate 5 and the other end welded to the bottom of the outer can 6 so that the adjacent unit cell 1 is connected. Connecting. In this figure, the welding points are indicated by ●. Further, the lead plate 2 is pressed by a pair of welding electrode rods 3 disposed close to each other, and a large current is caused to flow through the welding electrode rods 3 for spot welding. The pair of welding electrode rods 3 for welding the lead plate 2 to the positive electrode cap 4 of the sealing plate 5 causes a welding current to flow through the lead plate 2 and the positive electrode cap 4 of the sealing plate 5 as shown by chain lines. 2 is welded to the positive electrode cap 4 of the sealing plate 5. Further, the welding electrode rod 3 for welding the lead plate 2 to the bottom of the outer can 6 allows a welding current to flow through the lead plate 2 and the outer can 6 to weld the lead plate 2 to the outer can 6. The lead plate 2 welded in this state is U-curved to form an assembled battery in which the cells 1 are arranged in a row.
[0004]
[Problems to be solved by the invention]
When the assembled battery connected in series via the U-curved lead plate is discharged, it flows along the lead plate 2 as shown by the arrows in FIG. In this figure, the welding points of the lead plate 2 are indicated by ◯. The assembled battery shown in this figure is not particularly problematic when the flowing current is small, but in applications where a large current flows, such as an electric tool or an electric vehicle, a voltage drop occurs due to the resistance of the lead plate 2, There was a problem that the operating voltage at the time of discharging the entire assembled battery was lowered.
[0005]
Pressing adjacent batteries and moving the opposing surfaces of the U-curved lead plate 2 in the manner indicated by the arrows in FIG. 3 to bring them into contact with each other is effective in reducing the voltage drop generated in the lead plate 2. There is. However, in practice, it is very difficult to make the opposing surface of the lead plate 2 always contact in a low resistance state. In particular, when the surface of the lead plate 2 is oxidized with time to increase the surface resistance or foreign matter is sandwiched, it is almost impossible to make electrical contact in an ideal state. For this reason, it is extremely difficult for an assembled battery in which a plurality of unit cells are connected via a lead plate to reduce the voltage drop due to the lead plate in an ideal state.
[0006]
The resistance of the connecting portion of the unit cells can be reduced, for example, by directly soldering the opposing electrodes of the unit cells. However, soldering has a drawback that it is easily corroded by the influence of the electrolyte solution leaking from the battery and cannot be used stably for a long time. Moreover, compared with welding, there is also a drawback that the strength of coupling is low and it is difficult to reliably connect.
[0007]
Such a defect can be eliminated by directly welding the positive electrode terminal and the negative electrode terminal of the cell 1 as shown in FIG. In the assembled battery shown in this figure, the center positions of the two unit cells 1 are shifted and connected in series. The welding electrode rod 3 for welding the upper and lower unit cells 1 is in contact with the lid of the lower unit cell 1 and the upper unit cell in contact with the outer can 6 in the figure. When a welding current is passed through the two welding electrode rods 3, the lid of the lower unit cell 1 and the bottom of the upper unit cell 1 are welded together.
[0008]
The assembled battery having this structure can reduce the resistance of the connecting portion of the unit cells. However, the assembled battery having this structure has a drawback that the upper and lower unit cells cannot be connected in a straight line because the electrode rod for welding is brought into contact with the lid of the lower unit cell. Furthermore, in order to connect a large number of unit cells in series, it is necessary to repeatedly weld the unit cells to connect the upper and lower unit cells, and there is a drawback that it takes time and effort to connect.
[0009]
The present invention has been developed for the purpose of solving such drawbacks. An important object of the present invention is to provide an assembled battery and a method for manufacturing the same, which can connect the single cells in an ideal state with an extremely simple structure and can minimize the voltage drop at the connecting portion of the single cells. .
[0010]
[Means for Solving the Problems]
In order to eliminate the above-described adverse effects, the present inventors have repeated a variety of experiments, and as a result, a welding current is allowed to flow through the single cell. Successfully connected in an ideal state. Moreover, the assembled battery welded by this method has succeeded in improving the battery performance in addition to reducing the resistance of the connecting portion of the unit cells.
[0011]
Therefore, according to the manufacturing method of the assembled battery of claim 1 of the present invention, the assembled battery is manufactured by connecting a plurality of single cells 1 in series in a row. The method of manufacturing the assembled battery is such that a plurality of single cells 1 are arranged in a line through the metal plate 9 or without the metal plate 9, and the electrode metals 11 of the positive electrode terminal and the negative electrode terminal are connected in series to each other. Then, the electrode rod for welding 3 is brought into contact with both ends of the assembled battery, and the unit cell 1 is energized with a large current pulse, and the electrode metal 11 of the positive electrode terminal and the negative electrode terminal is passed through the metal plate 9 or the metal plate. It welds directly without going through 9.
[0012]
[0013]
[0014]
[0015]
[0016]
[0017]
[0018]
Furthermore, in the method for manufacturing an assembled battery described in claim 2 of the present invention, a large current pulse is applied in a direction in which the unit cell 1 is discharged with the unit cell 1 in a charged state.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the example shown below illustrates the assembled battery for embodying the technical idea of the present invention, and the present invention does not specify the assembled battery as follows.
[0020]
Further, in this specification, in order to facilitate understanding of the scope of claims, the numbers corresponding to the members shown in the examples are referred to as “the scope of claims” and “the means for solving the problems”. It is added to the member shown by. However, the members shown in the claims are not limited to the members in the embodiments.
[0021]
The assembled battery shown in FIG. 5 has 10 unit cells 1 connected in series in a row. In the assembled battery of this figure, ten unit cells 1 are connected, but the assembled battery of the present invention does not specify the number of unit cells to be connected. Moreover, as shown in FIG. 6, the assembled battery of this invention can arrange | position the several cell 1 in a line, connect in series, and can arrange these in parallel and make an assembled battery.
[0022]
The unit cell 1 is an alkaline secondary battery such as a nickel-hydrogen battery or a nickel-cadmium battery that can be discharged with a large current. However, the battery pack of the present invention does not specify a single battery as an alkaline secondary battery. All batteries that have been developed or will be developed at the present time and can be discharged with a large current can be used as single cells.
[0023]
A nickel-hydrogen battery suitable for the unit cell 1 is manufactured by the following process.
A known sintered nickel positive electrode is used as one positive electrode. For the negative electrode, a paste-type hydrogen storage alloy having a known punching metal current collector attached thereto is used.
2 The positive electrode and the negative electrode are wound through a separator made of a nonwoven fabric made of polypropylene having a thickness of about 0.2 mm to form a spiral electrode group.
After the current collector plates are connected to the upper and lower sides of the three spiral electrode groups, the spiral electrode groups are inserted into an SC size battery can.
4. Electrolytic solution (8N KOH aqueous solution containing LiOH and NaOH) is poured into the outer can, and the opening of the outer can is hermetically sealed with a sealing body to obtain a nickel hydride storage battery having a nominal capacity of 2.2 Ah.
[0024]
The nickel-hydrogen battery produced as described above is activated as follows.
A 1 nickel-hydrogen battery is charged at room temperature at a current value of 0.1 C (220 mA) for 16 hours.
2 After 1 hour of rest, discharge at room temperature until the battery voltage drops to 1.0 V at a current value of 0.2 C (440 mA).
This charge / discharge cycle is repeated five times to activate a nickel-hydrogen battery used as a single battery.
[0025]
In order to compare how excellent the assembled battery of the present invention shows by using the nickel-hydrogen battery prepared as described above for the unit cell 1, a comparative assembled battery was produced as a prototype as follows. .
[0026]
[Battery of comparative example]
As shown in FIG. 1, the unit cells 1 that have been activated as described above are used, and these unit cells 1 are arranged in a line and connected in series via a U-curved lead plate 2. Connected to. The lead plate 2 was a nickel plate having a thickness of 0.15 mm, a width of 7 mm, and a length of 30 mm. As shown in FIG. 2, the lead plate 2 was spot-welded by resistance electric welding using a pair of welding electrode rods 3. After welding both ends of the positive electrode cap 4 of the adjacent unit cell 1 and the bottom of the outer can 6, as shown in FIG. 1, the lead plate 2 is bent in a U shape so that the unit cells 1 are arranged in a row. .
[0027]
In order to compare the characteristics of the assembled batteries of the present invention, assembled batteries of Examples 1 to 4 were prepared as follows. However, the assembled batteries of the following examples are charged with a single current 1 at 0.1 C (220 mA) for 6 hours, charged, and then energized with a large current pulse to be a positive electrode terminal and a negative electrode terminal. The electrode metal 11 was welded.
[0028]
[Example 1]
As shown in FIG. 7, the same unit cell used for the assembled battery of the comparative example is arranged so that the positive electrode terminal and the negative electrode terminal are in contact with each other, that is, so that the unit cells are connected in series. And keep it in a vertical row. In this state, the unit cells 1 at both ends are pressed by the welding electrode rod 3. The welding electrode rod 3 sandwiches the lead plate 8 for taking out and presses the unit cells 1 at both ends. In this state, a voltage of 240 V is applied by a pair of welding electrode rods 3 in the direction of discharging the assembled battery between the positive electrode and the negative electrode side of the assembled battery, and a current of 1 KA flows for about 15 milliseconds. Pulse energized. In this large current pulse energization, the lead plates 2 between the single cells 1 were welded to each other on the opposing surfaces of the U-curved lead plate 2 as shown in FIG. In this figure, the welding points are indicated by circles.
[0029]
[Example 2]
As shown in FIG. 9, as the metal plate 9, a circular nickel plate (thickness: 0.15 mm) having a diameter of 8 mm is sandwiched between the unit cells 1, and the ten unit cells 1 are held by the holding cylinder 7. A single battery 1 is connected by applying the same high-current pulse energization process as in Example 1 while arranging the batteries in a vertical row and pressing both ends of the assembled battery with a pair of welding electrode rods 3 via lead plates 8. did. In FIG. 9, the welding points are indicated by ◯.
[0030]
[Example 3]
An assembled battery was produced in the same manner as in Example 2, except that a nickel-phosphorous plated metal plate was used for the circular nickel plate used in Example 2. Nickel-phosphorous plating of a circular nickel plate had a plating thickness of 1 μm and a plating composition of Ni 89 wt% and P11 wt%. In this embodiment, a circular nickel plate obtained by plating nickel-phosphorous on the metal plate 9 is used. However, a nickel-phosphorous alloy can also be used for the metal plate 9.
[0031]
[Example 4]
A unit cell 1 having a conical protrusion 10 as shown in FIG. 10 on the upper surface of a sealing plate 5 as a positive electrode terminal is used, and a lead plate is sandwiched between the unit cells 1. An assembled battery was manufactured in the same manner as in Example 1 except that the positive electrode terminal of the adjacent unit cell 1 and the electrode metal 11 of the negative electrode terminal were placed in direct contact with each other, and placed in the holding cylinder 7. The protrusion 10 provided on the sealing plate 5 has a protruding height of 0.5 mm, a bottom surface diameter of 1 mm, and a pitch of adjacent protrusions 10 of 1 mm. The surface of the sealing plate 5 is nickel-phosphorous plated. In FIG. 10, the welding points are indicated by ◯.
[0032]
[Example 5]
The unit cell 1 is the same as the example 4 except that a conical protrusion having the same shape as that provided on the positive electrode terminal of the unit cell used in Example 4 is provided on the negative electrode terminal and the positive electrode terminal is planar. The assembled battery was manufactured.
[0033]
[Example 6]
In Example 2, an assembled battery was manufactured in the same manner as in Example 2 except that a circular nickel plate used as a metal plate was provided with a conical protrusion. The protrusion provided on the metal plate had a protruding height of 0.5 mm, a bottom surface diameter of 1 mm, and an adjacent protrusion pitch of 1 mm.
[0034]
When the high rate discharge characteristics of the assembled battery manufactured as described above were measured, it was as follows. However, the high rate discharge characteristics were measured in the following state.
1 After complete discharge, charge at 0.1 C (220 mA) for 16 hours.
2 After completing charging, leave it for 1 hour.
3 Thereafter, when the discharge current is 30 A and the voltage of the assembled battery reaches 8 V, the discharge is stopped.
When the voltage of the assembled battery at the intermediate time (1/2) of the four discharge times was measured, it was as follows.
[0035]
Battery of comparative example ... 10.1V
The assembled battery of Example 1 ... 10.4V
The assembled battery of Example 2 ... 10.6V
The assembled battery of Example 3 ... 10.7V
Battery pack of Example 4 ... 10.9V
Battery pack of Example 5: 10.9V
The assembled battery of Example 6 ... 10.8V
[0036]
From this measurement result, the assembled battery of the present invention has a higher output voltage in a large current discharge and extremely excellent high-rate discharge characteristics than the assembled battery of the comparative example in which the lead plate 2 is bent and connected.
[0037]
Furthermore, in the assembled batteries produced in Examples 1 to 6, the electrode plate was activated by energizing a large current pulse, and the substantial capacity immediately after production was improved. This feature was exhibited to the maximum when the unit cell was a nickel-hydrogen battery. This is because the nickel-hydrogen battery uses a hydrogen storage alloy for the negative electrode, and this hydrogen storage alloy has a disadvantage that the activity immediately after the manufacture of the unit cells is low. In the present invention, the unit cells are connected to each other. It is considered that the welding current for increasing the activity of the hydrogen storage alloy. Furthermore, in the above embodiment, a large current pulse was applied in the direction of discharging the charged unit cell, and the unit cells were connected in series, but a large current pulse was applied in the direction of charging the unit cell. It can also be connected in series.
[0038]
【The invention's effect】
Method for producing a set batteries of the present invention, an extremely simple structure, the unit cells are connected in an ideal state, there is a feature that can extremely reduced voltage drop of the connection portion of the cells. It method set batteries of the present invention, by contacting a welding electrode rod at both ends of the battery pack, the electrode metal of positive and negative terminals of the unit cells adjacent via a metal plate, or metal This is because the plurality of single cells are connected in series in a row by welding directly without using a plate. Thus, the manufacturing method set batteries welding the unit cells adjacent directly, the Hesi voltage drop due to resistance of the lead plate electrode, the operating voltage at the time of discharging the entire battery pack, in particular, the output of the large-current discharge There is a feature that high voltage discharge characteristics can be improved by increasing the voltage.
[0039]
Furthermore, the manufacturing method set batteries of the present invention, rather than to bypass the unit cell to charge the battery cells, or by passing a welding current in the discharge directions, so connected in series, all of the cells Can be connected in a straight line. This is because a plurality of single cells can be arranged in a straight line, and welding electrode bars can be brought into contact with both ends thereof for welding. Furthermore, since it can be connected in series in this state, there is also a feature that a large number of single cells can be reliably welded in one process.
[0040]
Furthermore, the manufacturing method set batteries of the present invention, in addition to being able to connect the unit cells in series in a very simple manner, to activate the electrode plate in the welding current for connecting the unit cells, immediately after production substantially Realizing the ideal feature of improving the capacity.
[Brief description of the drawings]
1 is a front view showing a conventional assembled battery. FIG. 2 is an enlarged front view showing a state in which a lead plate is resistance-electrically welded to a single battery. FIG. 3 is an enlarged view showing a state in which a current flows through the assembled battery shown in FIG. Front view [Fig. 4] Partial cross-sectional front view showing a conventional example of welding a single cell [Fig. 5] Front view of an assembled battery of an embodiment of the present invention [Fig. 6] of an assembled battery of another embodiment of the present invention FIG. 7 is a cross-sectional view showing a manufacturing process of the assembled battery shown in FIG. 5. FIG. 8 is a partially enlarged front view showing a state where the lead plate of the assembled battery of Example 1 of the present invention is welded. FIG. 10 is a partially enlarged front view showing a state in which the lead plates of the assembled batteries of Examples 2 and 3 of the present invention are welded. FIG. 10 shows a state in which the unit cell of the assembled battery of Example 4 of the present invention is welded. Partially enlarged front view [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Single cell 2 ... Lead plate 3 ... Electrode rod 4 for welding 4 ... Positive electrode cap 5 ... Sealing plate 6 ... Exterior can 7 ... Holding cylinder 8 ... Lead plate 9 ... Metal plate 10 ... Protrusion 11 ... Electrode metal

Claims (2)

In a method for manufacturing an assembled battery in which a plurality of unit cells (1) are connected in series in a row, the plurality of unit cells (1) are connected via a metal plate (9) or a metal plate (9). Connect the electrode metal (11) of the positive electrode terminal and the negative electrode terminal in series with each other, and connect the electrode rod for welding (3) to both ends of the assembled battery in this state. It is characterized by flowing a current pulse energizing welding current and welding the electrode metal (11) of the positive terminal and the negative terminal directly through the metal plate (9) or without going through the metal plate (9). Manufacturing method of assembled battery. The method for producing an assembled battery according to claim 1 , wherein the single battery (1) is charged and a large current pulse is applied in a direction in which the single battery (1) is discharged.

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