JP2002298824A - Sealed battery and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed battery having improved highly efficient discharge property by putting one electrode in contact with the inner wall of a metal facing can for lowering the contact resistance. SOLUTION: The sealed battery comprises a positive electrode 20 and a negative electrode, 10 at least one of which has active material layers 12, 13 on both faces of a conductive core 11; the end of the conductive core 11 is provided with a core-exposed portion 11a, and the outer periphery face of the facing can 40 is provided with a recess 41 projecting inward of the battery; and the recess 41 can be put in contact with at least part of the core exposed portion 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer can having an opening serving also as a terminal of one electrode, and a spiral in which a positive electrode and a negative electrode housed in the outer can are spirally wound via a separator. TECHNICAL FIELD The present invention relates to a sealed storage battery provided with a spiral electrode group and a sealing body serving also as a terminal of the other electrode provided in an opening of an outer can and a method for manufacturing the same, and particularly an electrode arranged at the outermost periphery of a spiral electrode group The present invention relates to a current collecting structure between a battery and an outer can.

[0002]

2. Description of the Related Art In recent years, with the spread of various electric, electronic and communication devices including cordless devices, lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, lithium secondary batteries have been used as power sources for these devices. Sealed power storage such as batteries has become widely used. In these storage batteries, a separator is interposed between a positive electrode and a negative electrode, and these are spirally wound to form an electrode group. The electrode group is housed in a metal outer can, and the opening is formed in the metal outer can. The sealing body is hermetically sealed by being mounted with an insulating gasket interposed therebetween.

By the way, in order to collect one electrode of such a sealed type storage battery to a metal outer can, a current collecting tab is welded to a conductive core of one electrode, and then the current collecting tab is connected to a metal. It was intended to be welded to the inner bottom surface of the outer can. For this reason, a process for welding the current collecting tab to the conductive core or for welding the current collecting tab to the inner bottom surface of the metal outer can is required, and the manufacturing process is increased, and this type of sealing is required. There is a problem that the type storage battery cannot be easily manufactured.

[0004] Therefore, a sealed storage battery in which one electrode arranged at the outermost periphery of an electrode group is brought into direct contact with the inner wall of a metal outer can has been widely adopted. In this type of sealed storage battery, one of the electrodes arranged on the outermost periphery of the electrode group is only brought into contact with the inner wall of the metal outer can, so that the current collecting tab is welded to the conductive core, or Since there is no need to provide a step of welding the current collecting tab to the inner bottom surface of the metal outer can, this type of sealed storage battery can be easily manufactured.

[0005]

However, simply contacting the active material layer with the inner wall of the metal outer can results in a large contact resistance, which causes a problem that a voltage drop occurs during discharge. For this reason, after the one electrode arranged at the outermost periphery of the electrode group is brought into contact with the inner wall of the metal outer can, a sealed storage battery in which an annular groove is provided near the center or at the upper and lower parts of the metal outer can. Is disclosed in JP-A-9-2935.
No. 29 has been proposed. In the sealed type storage battery proposed in Japanese Patent Application Laid-Open No. 9-293529, an annular groove is provided near the center or at the top and bottom of the metal outer can, so that one of the outermost ones arranged at the outermost periphery of the electrode group is provided. Since the contact between the electrode and the annular groove is improved, the contact resistance is reduced, and good discharge characteristics can be obtained.

However, when the conductivity of the active material layer is low, an annular groove is provided near the center or in the upper and lower portions of the metal outer can, and the annular groove is provided on one of the electrodes arranged on the outermost periphery of the electrode group. There was a problem that good discharge characteristics, particularly good high-rate discharge characteristics, could not be obtained even when the contact was made. This is because the conductivity of the active material layer is low and the contact resistance with the metal outer can is large.

Accordingly, the present invention has been made to solve the above-mentioned problems, and one electrode is brought into contact with the inner wall of a metal outer can so that the contact resistance is reduced, thereby achieving a high rate discharge. It is an object of the present invention to provide a sealed storage battery having excellent characteristics.

[0008]

In order to achieve the above object, a sealed storage battery of the present invention has at least one of a positive electrode and a negative electrode provided with an active material layer on both sides of a conductive core, and At least one end of the conductive core includes a core exposed portion that does not hold an active material layer, and a concave portion protruding inward of the battery is provided on an outer peripheral portion of the outer can. At least a part of the part is contacted.

As described above, when the recess formed on the outer periphery of the outer can and projecting toward the inside of the battery is in contact with at least a part of the exposed core, the conductivity of the exposed core is reduced. Since it is good, the current collecting properties of the outer can that also functions as the terminal of one electrode and the electrode of one electrode are improved. As a result, good discharge characteristics,
In particular, a sealed storage battery having excellent high-rate discharge characteristics can be obtained.

In this case, if the depth of the concave portion is too small, the contact between the concave portion and the exposed portion of the core is not good, and if the depth of the concave portion is too deep, the concave portion comes into contact with the other electrode. This may cause a short circuit or damage the electrode. For this reason, it is desirable that the depth of the concave portion is greater than the thickness of one surface of the active material layer and shallower than the thickness of both surfaces of the active material layer.

Further, in order to obtain such a sealed storage battery, the method for manufacturing a sealed storage battery of the present invention is characterized in that at least one of the positive electrode and the negative electrode does not hold the active material layer at at least one end of the conductive core. An active material holding step of holding the active material layers on both sides of the conductive core so as to have the core exposed portion, and projecting inward of the battery in advance on the outer peripheral portion of the outer can corresponding to the core exposed portion A concave part forming step of forming a concave part, and an electrode group inserting step of inserting a spiral electrode group provided with an electrode having a core exposed part into an outer case having a concave part formed therein; The concave portion formed in the outer peripheral portion of the core member contacts at least a part of the exposed portion of the core body.

Alternatively, in the method for manufacturing a sealed storage battery according to the present invention, at least one of the positive electrode and the negative electrode may be provided with a conductive core-exposed portion that does not hold an active material layer at at least one end of the conductive core. An active material holding step of holding an active material layer on both surfaces of the core, an electrode group insertion step of inserting a spiral electrode group including an electrode having a core exposed portion into an outer can, and a spiral electrode group A recess formed on the outer periphery of the outer can corresponding to the exposed portion of the core of the outer can in which a recess protruding toward the inside of the battery is formed. Is in contact with at least a part of the core exposed portion.

By employing these manufacturing methods,
Since the contact between the core exposed portion of one electrode having excellent conductivity and the concave portion provided on the outer peripheral portion of the outer can also serving as the terminal of one electrode becomes tight, the current collecting property of this contact portion is improved. Thus, a sealed storage battery having excellent discharge characteristics and high-rate discharge characteristics can be easily manufactured.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a nickel-cadmium storage battery will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a nickel-cadmium storage battery in the course of manufacture according to the present invention, and FIG. 2 is a cross-sectional view showing the nickel-cadmium storage battery of Example 1.
FIG. 3 is a cross-sectional view showing a nickel-cadmium storage battery of Example 2. FIG. 4 is a view showing a main part of an outer can used for the nickel-cadmium storage battery of Example 3.
FIG. 4A is a cross-sectional view thereof, and FIG. 4B is a bottom view thereof. FIG. 5 is a diagram showing a main part of an outer can used for the nickel-cadmium storage battery of Example 4,
FIG. 5A is a cross-sectional view, and FIG. 5B is a bottom view.

1. Preparation of Electrode Group A negative electrode active material slurry composed of a negative electrode active material mainly composed of cadmium oxide and a binder is applied to both surfaces of a conductive core 11 made of punched metal, and a negative electrode active material layer 12 is formed.
After forming 13, it was dried and cut into a predetermined shape to produce a cadmium negative electrode 10. When the negative electrode active material slurry is applied, the conductive core body 11 is formed such that a part of the conductive core body 11 at the end in the width direction of the cadmium negative electrode 10 is exposed. The negative electrode active material slurry was applied except for a part of the end in the width direction of No. 11. In this case, after the negative electrode active material slurry is applied to the entire surface of the conductive core 11, the negative electrode active material slurry applied to a part of the widthwise end of the conductive core 11 is removed to remove the core. The body exposed portion 11a may be formed.

On the other hand, a punching metal (conductive core) 2
After the nickel sintered porous body 22 is formed on the surface of the nickel sintered body 22, the nickel sintered porous body 22 is filled with a positive electrode active material mainly composed of nickel hydroxide by a chemical impregnation method.
Was prepared. Also in this case, the conductive core 21 is partially exposed at the end of the nickel positive electrode 20 in the width direction, and the core exposed portion 21 is exposed.
The nickel sintered porous body 22 is formed such that a is formed. When the nickel sintered porous body is not used, the conductive core 21 made of punched metal is
A positive electrode active material slurry composed of a positive electrode active material mainly composed of nickel hydroxide and a binder is applied, and a nickel positive electrode 20 is coated.
May be produced.

Next, the cadmium negative electrode 10 and the nickel positive electrode 20 are used, and a separator 3 is interposed therebetween.
The spirally wound electrode groups a and b were formed by spirally winding the electrodes with 0 interposed therebetween. In this case, as shown in FIGS. 1 and 2, a spiral-shaped coil formed by spirally winding the core exposed portion 11 a of the cadmium negative electrode 10 and the core exposed portion 21 a of the nickel positive electrode 20 in different directions. The electrode group is referred to as an electrode group a, and FIG.
As shown in the figure, the core exposed portion 11a of the cadmium negative electrode 10
And a spirally wound electrode group formed by spirally winding the core exposed portion 21a of the nickel positive electrode 20 in the same direction as an electrode group b.

2. 1. Manufacture of Nickel-Cadmium Storage Battery (1) Example 1 First, a bottomed cylindrical outer can (nickel external terminal is provided on the bottom surface) 40 in which nickel is plated on iron is provided. The electrode group a produced as described above was inserted into the cadmium negative electrode 10 such that the exposed core portion 11a of the cadmium negative electrode 10 was downward. Thereafter, a sealing body 45 having an annular insulating gasket 46 mounted on the outer peripheral portion is prepared.
A positive electrode current collector lead extending from a positive electrode current collector (not shown) was spot-welded to the bottom surface of the sealing body 45.

Next, an electrolytic solution (8 mol / l potassium hydroxide (KOH) aqueous solution containing lithium hydroxide (LiOH) and sodium hydroxide (NaOH)) was injected into the outer can 40. Next, after a drawing process was performed on the outer peripheral portion above the outer can 40 to form a drawing portion 40a, the sealing body 45 was placed on the drawing portion 40a. Thereafter, the opening of the outer can 40 was sealed by caulking the opening edge of the outer can 40 inward, and a nickel-cadmium storage battery Z was assembled.

Next, as shown in FIG. 2, the lower outer peripheral portion of the outer can 40 corresponding to the core exposed portion 11a formed on the cadmium negative electrode 10 is subjected to drawing to form a concave portion (a convex portion when viewed from inside the battery). 41 was formed to obtain a nickel-cadmium storage battery A of Example 1. When the concave portion 41 is formed on the lower outer peripheral portion of the outer can 40, the inner wall of the outer can 40 projects into the battery and comes into contact with the core exposed portion 11a. In this case, the depth of the concave portion 41 (the height of the convex portion) is determined by the conductive core 11.
The active material layers 12, 1 formed deeper than the thickness of the active material layer 12 formed on one surface of the conductive core 11 and formed on both surfaces of the conductive core 11.
The pressing force was adjusted so as to be shallower than the thickness of No.3.

(2) Example 2 First, the electrode group b prepared as described above was inserted from the opening of the outer can 40 with the core exposed part 11a of the cadmium negative electrode 10 facing upward. Example 1 described above
A nickel-cadmium storage battery was assembled in the same manner as described above. Next, as shown in FIG. 3, the upper outer peripheral portion of the outer can 40 corresponding to the core exposed portion 11a formed on the cadmium negative electrode 10 is subjected to drawing to form a concave portion (a convex portion when viewed from inside the battery) 4.
2 and the nickel-cadmium storage battery B of Example 2
And Also in this case, the depth of the concave portion 42 (the height of the convex portion) is larger than the thickness of the active material layer 12 formed on one surface of the conductive core 11 and formed on both surfaces of the conductive core 11. The pressing force was adjusted so as to be shallower than the thickness of the active material layers 12 and 13.

(3) Embodiment 3 First, a cylindrical outer can (bottomed outer surface is to be a negative electrode external terminal) 50 in which nickel is plated with iron is prepared, and as shown in FIG. A plurality of recesses (projections when viewed from inside the battery) 51, 51,... Were formed at predetermined intervals in the lower outer peripheral corner of the outer can 50. Thereafter, the electrode group a manufactured as described above was inserted from the opening of the outer can 50 so that the core exposed portion 11a of the cadmium negative electrode 10 was downward, and the same as in Example 1 described above. The nickel-cadmium storage battery C of Example 3 was obtained. In addition, the electrode group a
Is inserted, the core exposed portion 11a comes into contact with a concave portion (a convex portion when viewed from inside the battery) 51 in which the inner wall of the outer can 50 projects into the battery.

(4) Example 4 First, a cylindrical outer can (bottomed outer surface is to be a negative electrode external terminal) 60 in which nickel is plated with nickel is prepared, and as shown in FIG. An annular groove (recess) 61 was formed at a corner of the outer periphery of the lower portion of the outer can 60. Thereafter, the electrode group a produced as described above was inserted from the opening of the outer can 60 so that the core exposed portion 11a of the cadmium negative electrode 10 was downward, and the same as in Example 1 described above. A nickel-cadmium storage battery D of Example 4 was obtained. When the electrode group a is inserted from the opening of the outer can 60, the core exposed portion 11a is set so that the inner wall of the outer can 60 comes into contact with an annular groove (projecting portion when viewed from inside the battery) 61 protruding into the battery. Become.

3. Measurement of Internal Resistance Next, the internal resistance (mΩ) of each of the batteries A and Z prepared as described above was measured using 20 batteries A and Z, respectively. The results are shown in Table 1 below. The result was as follows. In Table 1 below, the minimum value, the maximum value, and the average value of the actually measured values are shown.

[0025]

[Table 1]

As is clear from the results shown in Table 1, in the battery Z in which the negative electrode 10 is simply brought into contact with the outer can 40, the average value of the internal resistance is large and the variation in the resistance value of each battery is large. You can see that. On the other hand, in the battery A in which the concave portion 41 is provided in the lower part of the outer can 40, the average value of the internal resistance is small, and the variation in the resistance value of each battery is small. This tendency is due to the
0, a battery B provided with a concave portion 42 at the upper part, a battery C provided with a concave portion 51 at a corner of a lower outer peripheral portion of the outer can 50, and an outer can 6
The same was true for the battery D in which the annular groove 61 was provided at the corner of the outer periphery of the lower part of No. 0.

This is because the exposed core 11a has good conductivity.
Are concave portions (projections protruding into the battery) 41 or 42 provided in the outer can 40, concave portions (projections protruding into the battery) 51 provided at corners of a lower outer peripheral portion of the outer can 50, This is because it is in contact with an annular groove (projection protruding into the battery) 61 provided at a corner of the outer periphery of the lower portion of the can 60.

As described above, according to the present invention, the concave portions 41 (42, 51, 61) formed on the outer periphery of the outer can 40 (50, 60) and projecting inward of the battery are electrically conductive. Is in contact with at least a part of the good core exposed portion 11a, so that the current collection between the outer can 40 (50, 60) and the negative electrode is improved. As a result, a sealed storage battery having good discharge characteristics, particularly good high-rate discharge characteristics, can be obtained. In the above-described embodiment, an example in which the present invention is applied to a nickel-cadmium storage battery has been described. However, the present invention is not limited to a nickel-cadmium storage battery.
It goes without saying that the present invention can be applied to various sealed storage batteries such as nickel-hydrogen storage batteries, lithium secondary batteries, and lead storage batteries.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a nickel-cadmium storage battery in the course of manufacture according to the present invention.

FIG. 2 is a cross-sectional view illustrating the nickel-cadmium storage battery of Example 1.

FIG. 3 is a cross-sectional view illustrating a nickel-cadmium storage battery according to a second embodiment.

FIG. 4 is a view showing a main part of an outer can used for the nickel-cadmium storage battery of Example 3, FIG. 4 (a) is a sectional view, and FIG. 4 (b) is a bottom view.

FIG. 5 is a view showing a main part of an outer can used for the nickel-cadmium storage battery of Example 4, FIG. 5 (a) is a cross-sectional view thereof, and FIG. 5 (b) is a bottom view thereof.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Cadmium negative electrode, 11 ... Conductive core, 11a ... Core exposed part, 12, 13 ... Active material layer, 20 ... Nickel positive electrode, 21 ... Conductive core, 21a ... Core exposed part, 22 ... Nickel firing Porous body, 30 ... separator, 40 ... outer can,
40a: squeezed portion, 41: concave portion, 42: concave portion, 45: sealing body, 46: insulating gasket, 50: outer can, 51: concave portion, 60: outer can, 61: annular groove, A, B, C, D, Z
... nickel-cadmium storage batteries, a, b ... spiral electrode group

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Claims (5)

[Claims] An outer can having an opening serving also as a terminal of one electrode; a spiral electrode group in which a positive electrode and a negative electrode housed in the outer can are spirally wound via a separator; A sealed storage battery provided with a sealing member that also serves as a terminal of the other electrode disposed in the opening of the outer can, wherein at least one of the positive electrode and the negative electrode has an active material layer on both surfaces of a conductive core. At least one end of the conductive core includes a core exposed portion that does not hold the active material layer, and includes a recess protruding inward of the battery on the outer periphery of the outer can. The sealed storage battery, wherein the recess is in contact with at least a part of the core exposed portion. 2. The sealed storage battery according to claim 1, wherein the depth of the recess is larger than the thickness of one surface of the active material layer and smaller than the thickness of both surfaces of the active material layer. 3. A spirally wound electrode group in which a positive electrode and a negative electrode are spirally wound via a separator is housed in an outer can having an opening serving also as a terminal of one electrode, and then the other electrode is placed in the opening. A method for manufacturing a sealed storage battery in which a sealing body serving as a terminal is mounted and hermetically sealed, wherein at least one of the positive electrode and the negative electrode does not hold an active material layer at at least one end of a conductive core. An active material holding step of holding an active material layer on both surfaces of the conductive core so as to have an exposed portion; and protruding inward of the battery in advance on an outer peripheral portion of the outer can corresponding to the exposed portion of the core. Forming a concave portion to form a concave portion, and inserting an electrode group including a spiral electrode group provided with an electrode having the core exposed portion into an outer can having the concave portion. The recess formed in the outer periphery of the can is the core Method for manufacturing a sealed storage battery is characterized in that so as to contact at least a portion of the output portion. 4. A spirally wound electrode group in which a positive electrode and a negative electrode are spirally wound via a separator is housed in an outer can having an opening serving also as a terminal of one electrode, and then the other electrode is placed in the opening. A method for manufacturing a sealed storage battery in which a sealing body serving as a terminal is mounted and hermetically sealed, wherein at least one of the positive electrode and the negative electrode does not hold an active material layer at at least one end of a conductive core. An active material holding step of holding an active material layer on both sides of the conductive core so as to have an exposed portion; and inserting a spiral electrode group including an electrode having the core exposed portion into the outer can. An electrode group inserting step, and a concave part forming step of forming a concave part protruding inward of the battery at an outer peripheral part corresponding to the core exposed part of the outer can into which the spiral electrode group is inserted. The recess formed in the outer peripheral portion of the outer can Method for manufacturing a sealed storage battery is characterized in that so as to contact at least a portion of the relaxin exposed portion. 5. In the recess forming step, the pressing force is adjusted so that the depth of the recess is larger than the thickness of one surface of the active material layer and smaller than the thickness of both surfaces of the active material layer. The method for producing a sealed storage battery according to claim 3, wherein the method comprises: